- Current Issue
- Online First
- Just Accepted
- Most Downloaded Archive
Volume 45,2025 Issue 8
-
DOI:
Abstract:
在广泛寒区工程中,岩体的冻融破坏是一种无法忽视的自然灾害.为探究冻融环境对寒区岩体工程稳定性的影响,以寒区红砂岩为对象,开展不同冻融次数(0,10,20,30次)和不同饱和(0、20％、40％、60％、80％、100％)岩石的单轴压缩试验,并对岩样进行SEM 微观结构分析.研究表明:随着冻融循环次数和饱和度的增加,红砂岩的裂纹闭合应力σcc、起裂应力σci、损伤应力σcd、峰值应力σc和抗冻系数Kfm 均逐渐降低,内部损伤逐渐加剧;红砂岩试件破坏形态由斜剪破坏和张拉破坏逐渐向""X""形破坏转变,并伴有少量碎块剥落;循环往复的冻融作用致使岩石内部原有微裂隙扩展和新裂纹出现,揭示了砂岩在不同冻融条件下的损伤演化特征.研究成果可为寒区岩体工程的稳定性及岩石的力学性质研究提供一定参考."
-
DOI:
Abstract:
充填配料系统的计量误差是影响充填体质量关键因素,为揭示由计量误差引起的质量分数和泵送剂掺量波动对充填材料工作性能影响的主效应、交互效应、显著性、规律和机理,并确定工业施工标准,基于水泥水化机理和泵送剂作用原理,利用响应面和方差分析法开展力学性能、流动性能和流变性能实验设计和实验结果分析。结果表明：(1)质量分数和泵送剂掺量的±1%波动主效应显著影响充填材料28d强度、稠度、塌落度、扩展度和平均黏度,交互效应显著影响28d强度、稠度和平均黏度,影响规律有正相关、负相关和先负后正；(2)质量分数和泵送剂掺量波动会导致充填料浆内自由水比例发生变化,从而影响充填材料工作性能；(3)质量分数波动范围应保持在78-79%,泵送剂掺量波动范围应保持在1%-2%。研究结果为充填配料系统建设和配料设备精度调校提供理论依据,具有重要工业生产指导意义。
-
DOI:
Abstract:
In this paper, CaO-MgO-Al2O3-SiO2 (CMAS) slag glass-ceramics were successfully prepared by adding different contents of cadmium using glass-ceramics preparation technology with solid wastes such as tailings and fly ash as the main raw materials. The crystallization characteristics of cadmium-doped glass-ceramics were characterized by DSC, XRD, SEM and Raman spectroscopy. At the same time, the density, flexural strength, Vickers hardness toxicity, thermal expansion coefficient and leaching test (TCLP) were discussed. The results show that with the increase of cadmium content, the full width at half maximum of the crystallization peak gradually increases, which promotes the crystallization of glass-ceramics. However, the main crystal phase has not changed significantly. At the same time, the relevant elements in the glass-ceramics have a depolymerization effect due to the addition of cadmium, which changes the microstructure of the glass. In addition, the flexural strength and Vickers hardness of the glass show a strengthening trend. Through TCLP detection, the highest leaching rate of cadmium is 0.03037 mg / L, which is far lower than the highest leaching concentration of hazardous waste stipulated by the state. Therefore, the preparation of glass-ceramics by adding cadmium is a feasible way to solve the resource utilization and harmless treatment of solid waste.
-
ZUO Hao, ZHANG Guangyou, ZHOU Zesen, LI Shibin, QU Zhi
DOI:
Abstract:
Based on the problem of impact instability of gob-side entry retaining with direct-covering thick and hard roof, taking the gob-side entry retaining of 63upper 06 working face of a mine in Shandong Province as the engineering background, the research methods of field measurement, theoretical analysis and numerical simulation were used to analyze the breaking characteristics and energy release mechanism of direct-covering thick and hard roof and energy criterion of impact instability of gob-side entry retaining． Then, the mechanism of impact instability of gob-side entry retaining with direct-covering thick and hard roof was clarified． The results show that the instability evolution of the “plate-shell” overburden structure in the stope with direct-covering thick and hard roof has the characteristics of long period, wide range of overlying strata migration control and prominent dynamic load of roof breaking． Compared with the general roadway, this kind of gob-side entry retaining is more affected by dynamic load disturbance． Affected by the large-scale hanging strata of the direct-covering thick and hard roof, the movement of the “plate-shell” overburden structure will increase the advanced static load of the gob-side entry retaining, at the same time, it will transmit severe dynamic load downward． The combined action of the static load and dynamic load causes the direct-covering thick and hard roof to break and produce super-strong dynamic load, which causes the impact instability of the gob-side entry retaining． The field case shows that the initial fracture size of the direct-covering thick and hard roof is 58m,the fracture release energy is 3.5×107 J, and the energy transmitted to the gob-side entry retaining is 8.9×105 J; the periodic fracture size is 28m, there lease energy is 1.7×107 J, and the energy transmitted to the gob-side entry retaining is 4.36×105 J, which is less than the critical impact energy 1.25×106 J of the 63upper 06 gob-side entry retaining, indicating that the initial fracture or periodic fracture of the direct-covering thick and hard roof will not induce the impact displacement of gob-side entry retaining under conventional conditions． The comprehensive prevention and control measures of “uniform or low speed mining of working face＋ deep hole blasting pre-splitting of direct-covering thick and hard roof＋ strengthening advanced support” were put forward, and industrial tests were carried out on the coal mine site． The research results can provide some reference for the prevention and control of impact instability of gob-side entry retaining with direct-covering thick and hard roof under similar engineering geological conditions．
Volume 45,2025 Issue 8
-
Numerical Modelling of Flocculation Dynamics of Fine Mineral Particles by CFD-PBM Coupling Approach
Abstract:
The turbulence characteristics and operation conditions have significant effects on particle flocculation behavior. The mathematical model of particle flocculation dynamics was established based on the local turbulence kinetic energy dissipation rate and slurry viscosity correction. Based on the validation of flow field velocity and mean floc size between the experiments and simulation, the CFD-PBM coupling approach was constructed and the flocculation behavior was numerical simulated in a lab-scale deep cone thickener. In addition, the effect of feed solid concentration on turbulence and floc size distribution was investigated. The results show that the turbulence kinetic energy dissipation rate above the annular shelf is higher by two orders than that below the shelf. The feed solid concentration has a more significant influence on the turbulence kinetic energy dissipation rate below the shelf than above the shelf. The turbulence kinetic energy dissipation rate increases first with feed solid concentration and then decreases. In the investigated range of feed solid concentration (3%-20%), the moderate feed solid concentration facilitates the mean floc size of 180 μm. The research provides guidance for modelling of particle flocculation dynamics induced by turbulence, thereby optimizing the operation parameters for flocculation thickening process.
- 1
-
Analysis on Stope Structural Parameters of a Mine Using Cut-and-Fill Mining Method Based on FLAC3D Numerical Simulation
Abstract:
As the mining depth increases, traditional mining methods face greater safety hazards and environmental pressures. The filling method, as an environmentally friendly mining technology, has been widely applied in mining operations. Taking a large copper mine as the research object, this study combines theoretical analysis and numerical simulation methods to optimize the stope structural parameters of upward layered point-pillar filling mining. Through numerical simulation analysis of parameters such as stope length, pillar size, and pillar center spacing, the study systematically evaluates the impact of different stope structural parameters on geological stability, mine safety, and production capacity. The results indicate that when the stope length is 65 meters, the pillar size is 5×5 meters, and the pillar center spacing is 15 meters, the stability of the stope is relatively high, and production efficiency is optimal. The proposed optimization scheme for the stope structural parameters not only ensures safe mining operations but also improves resource utilization, providing a scientific basis for the application of filling mining technology in similar mines.
- 1
-
Compressive strength prediction of fiber-reinforced cemented tailings backfill based on the HOA-residual-stacking algorithm
Abstract:
In order to address the challenge of insufficiently predicting the compressive strength (UCS) of fiber-reinforced cemented tailings backfill (FRCTB), an improved ensemble learning model of Stacking based on a weighted residual (R) mechanism has been proposed based on 364 groups of experimental data collected from the literature in this study. Initially, the model integrated six heterogeneous base learners and four meta-learners to construct an ensemble framework. The parameters of the base learners were optimized utilizing the Hippopotamus Optimization Algorithm (HOA). The prediction outcomes of the base learners were derived through five-fold cross-validation. Concurrently, adaptive weights were assigned to each base learner in line with their respective prediction errors. Subsequently, the residual features were constructed to serve as input for the meta-learner and 6 single models were set as controls for horizontal comparison of prediction accuracy. Eventually, an interpretability analysis was introduced to explore the influencing factors. Consequently, the results have indicated that among the single models, the light gradient boosting machine performs best with an R2 of 0.8870, whilst the improved Stacking model with support vector regression as the meta-learner achieves the optimal model performance with an R2 of 0.9470, and reductions of 34.53% and 33.94% in mean absolute error and root mean squared error have occurred in contrast with the single models, respectively. The interpretability analysis have revealed that the fiber content become one of the key factors affecting the compressive strength of FRCTB. On account of this, the research findings have provided an effective method for predicting the compressive strength of FRCTB, contributing to enhancing the stability of backfill body and reducing the production costs.
- 1
-
Demonstration of unmanned intelligent perception technology and application under the influence of dust in open-pit mines
Abstract:
The perception system of the vehicle in the process of unmanned truck transportation in open-pit mine is susceptible to the influence of sandstorm, dust and other weather, which reduces the detection and tracking ability of key targets, resulting in target misses, misdetections and stops. In order to study the safe and efficient perception technology of unmanned driving under the influence of dust, the intelligent perception model and scheme of unmanned truck dust were proposed by using deep learning algorithm, point cloud data processing technology and multi-sensor fusion method, and experimental verification was carried out, the dust classification strategy and basis of unmanned operation were determined, and the trained model was evaluated on the test set. The results show that the prediction average intersection to union ratio index mIoU index is 87.3%, of which the IoU of dust category reaches 90.7%, indicating that the perception model has a high recognition rate for dust categories, which can fully meet the needs of unmanned driving in mining areas for dust scene recognition, effectively improve the vehicle perception ability in the unmanned environment of open-pit mines, improve the perception accuracy and sensitivity of the environment, and have remarkable application effects in the field, providing guarantee for the safe operation of unmanned mining trucks.
Keywords: open-pit mine; fugitive dust; unmanned; intelliSense; Grading of experience- 1
-
Collaborative Framework for Intelligent Emergency Systems in Coal Mines: Multi-source Data Fusion and Dynamic Allocation of AI Accountability
Abstract:
To address the conflict between the agility of technological iteration and the lag of institutional updates in intelligent emergency systems during coal mine digital transformation, this study constructs an effective collaborative mechanism to enhance safety governance efficacy. Specifically, we propose a "Technology-Institution Synergy Threshold Model" and establish a multi-source data fusion framework with a tripartite "Institution-Technology-Insurance" collaborative mechanism. At the technological level, federated learning dynamically optimizes data weights while OPC UA protocols unify semantic standards, effectively resolving heterogeneous sensor protocol issues underground. At the institutional level, AI authority-responsibility dynamic allocation rules are designed, accompanied by an innovative algorithm registry and liability insurance linkage mechanism, systematically filling gaps in intelligent emergency governance. Empirical results demonstrate an 80% improvement in data fusion efficiency and reduction of false gas alarms to 4.3% at Yujialiang Mine; whereas Hongqinghe Mine achieved 60% faster ventilation response through an eco-priority coefficient optimization mechanism. The proposed synergy threshold model and implementation mechanisms provide a quantitative toolkit for transforming coal mine safety governance from passive response to active defense, further establishing an innovative "Technology-Institution-Ecology" collaborative paradigm for green mine development.
- 1
-
Research progress on soil improvement by coal gangue and ecological restoration in mining area
Abstract:
Aiming at the problems of land occupation, soil degradation and environmental pollution caused by the accumulation of a large amount of coal gangue associated with coal mining, the resource utilization of coal gangue as a potential soil amendment and ecological restoration material in mining areas was systematically discussed. Coal gangue is rich in silicon-aluminum minerals, organic matter and trace elements. Through microbial and hydrothermal activation modification technology, the bioavailability of key nutrients such as silicon, potassium and phosphorus can be improved, which has the advantages of environmental friendliness and low energy consumption. Studies have shown that activated coal gangue can significantly optimize the pore structure of degraded soil, enhance its water and fertilizer retention performance, improve soil organic matter content and fertility level, and play an active role in promoting soil carbon sequestration. In terms of ecological restoration in mining areas, modified coal gangue has been successfully applied to reclamation projects in subsidence areas. At the same time, artificial soil can be prepared to effectively support vegetation reconstruction and soil and water conservation. The resource utilization of coal gangue not only provides theoretical support and technical path for the high value and large-scale consumption of bulk industrial solid waste, but also has important practical significance in promoting the ecological reconstruction of mining areas, the sustainable improvement of degraded soil and the realization of the goal of ' double carbon '.
- 1
-
Reliability Analysis and Application Research of Automatic Monitoring Technology for Acoustic Environment in Mining Areas
Abstract:
Noise pollution in mining areas is a prominent problem in the construction of green mines, and achieving precise and continuous monitoring is crucial for environmental protection and occupational health. To address the lack of timeliness and continuity in traditional manual monitoring applications in mining areas, based on the research background of a typical mining area committee in Hunan Province, eight functional areas including open-pit mines, beneficiation plants, transportation work areas, and living areas were selected to carry out 24-hour continuous manual and automatic noise monitoring. Linear regression and bias analysis were conducted to verify the reliability of automatic monitoring technology by comparing over 190 sets of equivalent sound level data per hour. The results showed that the automatic monitoring and manual monitoring results were highly consistent, with linear regression slopes ranging from 0.983 5 to 1.055 4, correlation coefficients (r) above 0.997, and absolute deviations controlled within ±1 dB, fully demonstrating the applicability and accuracy of the automatic monitoring system in complex mining environments. The monitoring data also revealed that the noise level in the production area (70-85 dB) was significantly higher than that in the living area (<55 dB), and after prevention and control measures were taken, the sound level was reduced by about 20-30 dB compared to the source intensity, with significant prevention and control effects. This can provide data support and theoretical basis for research on automatic noise monitoring.
- 1
-
Research on the Realization Mechanism of Ecological Product Value in Mine Ecological Restoration of Southern Hilly Regions: Evidence from Jiangxi Province
Abstract:
Against the backdrop of ecological civilization advancement, mine ecological restoration has shifted from solely addressing environmental remediation towards realizing the value of ecological products. This study systematically investigated synergies between mine restoration and ecological product value creation in Jiangxi Province, a representative area of China’s southern hilly-mountainous region. Jiangxi Province has pioneered diverse Ecological Restoration + models, such as Ecological Restoration + Land remediation, Ecological Restoration + Cultural-tourism Integration, Ecological Restoration +New Energy Development and Ecological Restoration + Industrial Clustering. These approaches successfully converted disused mining sites into valuable ecological assets such as arable land, carbon sinks, and cultural-tourism resources, establishing an integrated production-supply-sales value chain. Analysis revealed a tripartite foundation enabling this value realization: policy impetus, market-driven mechanisms, and multi-stakeholder collaboration. Nevertheless, persistent challenges included funding and technological limitations, ambiguous accountability mechanisms, underdeveloped market systems, and insufficient policy coordination. To address these, the study recommended strengthening institutional safeguards, facilitating social capital investment, expanding carbon trading and ecological compensation schemes, and advancing digital governance. These measures aimed to provide a scalable framework for synergistically enhancing mine restoration and ecological product value in southern hilly and mountainous regions, demonstrating how lucid waters and lush mountains could become invaluable assets.
- 1
-
Enhanced Cross-Spatial Scale-Integration Based Foreign Object Detection Method for Underground Mines Conveyor Belt
Abstract:
Existing foreign object detection methods for underground mine conveyor belts often employ channel dimension reduction to model cross-channel relationships. This approach typically leads to high computational costs and suboptimal detection accuracy. A foreign object detection method based on scale sequence fusion and cross-spatial learning attention is proposed. The EMA module reshapes partial channels into the batch dimension and groups channels into multiple sub-features, ensuring effective distribution of spatial-semantic characteristics within each group. The SSFF module horizontally stacks multi-scale feature maps and extracts scale-sequence features using 3D convolution, effectively integrating high-dimensional semantic information from deep layers with detailed spatial information from shallow layers. The DASI module adaptively weights high-dimensional and low-dimensional features to enhance small object recognition. Experimental results demonstrate that the proposed method achieves a mean Average Precision (mAP) of 89.7%, representing a 1.5 percentage point improvement over the baseline model. Detection accuracy for large foreign objects increases by 4.1 percentage points, while the parameter count is reduced to 2.48 million. Compared with mainstream models, this framework exhibits superior detection accuracy and lightweight design, demonstrating significant potential for real-time foreign object detection in underground mining environments.
- 1
-
Research on Horizontal Lateral Deep Hole Blasting Mining Technology
Abstract:
Addressing the challenge of achieving safe and efficient mining, this study develops a horizontal deep hole blasting technique, taking a copper-nickel mine in Xinjiang as the engineering background. Building upon this technique, a comprehensive research methodology incorporating theoretical and empirical analysis, numerical simulation, and field testing was employed to investigate blasting parameters. Firstly, based on theoretical and empirical calculations, the horizontal medium-length hole parameters were determined as follows: a diameter of 65 mm, employing continuous charging with in-hole initiation, stemming intervals with lengths of 1 m and 2 m respectively, and a millisecond delay of 25 ms. Secondly, numerical simulations demonstrated that with a minimum burden of 1.5 m and a hole spacing ranging from 1.0 to 1.5 m, effective rock fragmentation to form a medium-length hole stope could be achieved while ensuring the stability of the backfill roof. Finally, field trials validated the approach. The resulting trial stope exhibited a regular morphology, with no significant overbreak, large boulders, or excessive fines generation. The backfill roof remained intact, and the estimated overbreak/underbreak was below 10%, indicating satisfactory blasting performance. This research provides valuable insights and references for achieving safe and efficient mining operations in similar types of mines.
- 1
-
The grouting reinforcement technology and application for soft and broken surrounding rock roadway in the sublevel caving stope under complex cavity interference
Abstract:
The stability maintenance of soft and broken surrounding rock tunnels under complex conditions has always been a key technical challenge in the mining industry. In the last section of the caving stope in the West Second Mining Area of Jinchuan Longshou Mine, the mining drifts experienced extensive deformation and damage within one month after excavation and support, posing a threat to safety and production. The analysis indicates that the main cause of the significant deformation and damage is the soft and broken orebody and the untopped voids beneath the floor filled with materials. A secondary support scheme of "grouting reinforcement + anchor shotcrete mesh" was proposed for the deformed drifts. Five grouting holes were evenly arranged at each grouting section, with a depth of 2.2m and a grouting pitch of 2m. The parameters of the secondary anchor shotcrete mesh were the same as those of the initial support. Field application proved that this scheme effectively suppressed the deformation and damage of the mining drifts, reducing the deformation by more than 80% and the eyebrow line damage rate by more than 50% compared to the initial support scheme. Moreover, no large-scale repair was required for the drifts throughout the entire cycle after the secondary reinforcement. The research results can provide reference and guidance for the tunnel support in similar mines.
- 1
-
Research on the wear law of filling pipeline in ultra-deep well and the technology of pressure regulation and wear reduction based on numerical simulation
Abstract:
With the depletion of shallow mineral resources, deep metal mining has become a key way to ensure the supply of resources. Although the paste filling technology can effectively control the ground pressure disaster in deep wells, the filling pipeline in ultra-deep wells has high vertical height and high potential energy, resulting in fast flow rate and high pressure of paste slurry, causing severe wear and slurry leakage risk of the pipeline, which seriously restricts the safe operation of the filling system. Aiming at the risk of flow velocity out of control and wear caused by high potential energy in ultra-deep well paste filling pipeline, the influence mechanism of paste coarse aggregate type, mass concentration ( negatively correlated with wear rate ), flow velocity ( linear positive correlation ) and geometric parameters was revealed by ANSYS simulation. A two-stage pressure regulation and wear reduction technology is innovatively proposed : a horizontal return loop pipe and an electric pressure regulating valve are added to the middle and lower parts of the pipeline, and the flow rate is adjusted to the safety threshold in stages, supplemented by a T-shaped buffer structure to optimize the flow pattern. The industrial application shows that the technology effectively alleviates the impact and cutting wear, reduces the risk of slurry leakage by 30 %, and increases the utilization rate of drilling by 25 %, which provides key technical support for the development of deep ground resources.
- 1
-
Research on ventilation regulation and control technology for corner-connecting stope clusters in large-panel areas of deep metal mines
Abstract:
To address the coupled "thermal-pollution" issue induced by complex diagonal ventilation in the large-scale mining of metal deep mines with large-panel, high-density stope clusters (7.5Mt/a), this study establishes a four-dimensional analytical framework. This framework integrates orthogonal experiments, the control variable method, Fluent numerical simulations, Ventsim ventilation calculations, and multiple linear regression. It reveals the critical role of selectively closing the crosscut air door in airflow path reconstruction and proposes an optimized diagonal ventilation network scheme based on this control method. Results show that after closing the 0# crosscut air door, fresh air is directed through the 2# crosscut into stopes. The ore-drift airflow increases from 10.8 m3/s to 30.7 m3/s, the regional air velocity rises from 0.1 m/s to 0.6 m/s, and the average roadway temperature drops to 26.03 ℃. This approach effectively resolves local airflow short-circuiting, enhances pollutant discharge efficiency, and improves the underground working environment. The study provides a theoretical basis and a practical engineering example for the precise and efficient regulation of ventilation systems in similar deep mine large panels.
- 1
-
Support Effect Comparison and Numerical Simulation Study of Multi-thin Interbedded Roadway in Wengfu Phosphate Mine
Abstract:
Aiming at the current situation of frequent instability of surrounding rock such as roof fall and rib spalling in a working face with weak interlayer in Wengfu Phosphate Mine, through field investigation and FLAC3 D numerical simulation, the surrounding rock control effects of conventional bolt-mesh-shotcrete support and bolt-mesh-shotcrete + steel arch + advanced support composite technology are systematically compared. The research shows that the weak interlayer contains 3.9 % kaolinite, and the expansion and softening in water is the main reason for the deterioration of surrounding rock. The numerical simulation shows that the composite support reduces the vertical displacement of the roadway from-8.33 mm to-6.67 mm ( a decrease of 19.93 % ), the horizontal displacement from 2.61 mm ( X direction ) and-1.64 mm ( Y direction ) to 1.27 mm and-0.58 ( a decrease of 51.3 % and 64.6 % ), the stress concentration is significantly alleviated, and the total failure unit is reduced by 10.85 %. The field application shows that the composite support reduces the monthly average accident rate from 0.6 times to 0.27 times (a decrease of 55.0 %) and effectively controls the large deformation of surrounding rock induced by multiple interlayers. The results provide a theoretical basis and key technical paradigm for safe excavation of roadways with dense weak interlayers.
- 1
-
Electrochemical kinetics of butyl xanthate on gold surface
Abstract:
To elucidate the electrochemical interaction mechanism between butyl xanthate and gold minerals under alkaline conditions and to provide a theoretical basis for optimizing the alkaline flotation process of gold-bearing sulfide ores, systematic investigations were conducted on the interfacial behavior of a gold electrode in a butyl xanthate solution at pH 9.18. Cyclic voltammetry (CV), Tafel polarization, and galvanostatic step techniques were employed. In the CV measurements within the potential range of 0.2-0.4 V, a characteristic oxidation peak was observed. Analysis determined this process to be a two-electron transfer reaction primarily yielding dixanthogen. Kinetic analysis revealed a forward reaction rate constant of 1.524 cm/s, indicating that this charge transfer process exhibits rapid kinetics. Tafel polarization studies demonstrated that the interaction strength between butyl xanthate and the gold electrode increased with rising collector concentration. Furthermore, the adsorption of xanthate molecules onto the gold surface was identified as the key rate-determining step. It was also found that physical factors such as grinding fineness and agitation intensity significantly influenced the interaction efficiency between the collector and the mineral. The exchange current density of dixanthogen on the gold electrode surface was measured as 0.075 A/m2 using the galvanostatic step technique. This value was highly consistent with the corrosion current density obtained via the Tafel method, verifying the reliability of the results. The results demonstrate that in the alkaline environment of pH 9.18, butyl xanthate undergoes rapid electrochemical oxidation (rate constant 1.524 cm/s) to form dixanthogen, which exhibits strong adsorption onto the gold surface. This constitutes the key mechanism for its effectiveness as a highly efficient collector for gold minerals.
- 1
-
Mechanism of CaSO4-MgO Composite Expansive Agent on Properties of Alkali-Activated Copper Slag-Slag Mortar
Abstract:
This study investigated the regulation of drying shrinkage in alkali-activated copper slag-slag mortar (CS-AAM) by incorporating a CaSO4-MgO composite expansive agent (CM). The effects of the CaSO4/MgO mass ratio in CM on the workability, hydration process, microstructural evolution, and macroscopic mechanical properties of CS-AAM were systematically examined, and the synergistic shrinkage-reduction mechanism of CM was elucidated. The results demonstrated that adjusting the CaSO4/MgO mass ratio effectively controlled the fluidity and setting time of CS-AAM paste. As the proportion of CaSO4 decreased, the formation of ettringite in the system was reduced, while the generation of brucite increased correspondingly. When the CaSO4:MgO?mass ratio reached 2:1, the CS-AAM exhibited optimal comprehensive performance with the densest microstructure. Compared to the control group, the 28-day compressive strength increased by 4.4%, while the 180-day drying shrinkage rate decreased by 40.9%.
- 1
-
Adaptive Progressive Point Cloud Filtering Algorithm for Mine Tunnel Deformation Monitoring
Abstract:
Raw point clouds acquired from mine roadways through three-dimensional (3D) laser scanning frequently contain significant noise interference. Existing filtering methods often face challenges in effectively balancing data simplification with the critical preservation of geometric features. Adaptive filtering techniques, capable of dynamically adjusting parameters based on the characteristics of the raw data, offer potential for enhancing subsequent deformation monitoring tasks. An adaptive progressive filtering algorithm is proposed to address these challenges. This method integrates an improved adaptive voxel filtering approach with a dynamic radius filtering algorithm employing hierarchical constraints. Specifically, the improved adaptive voxel filtering technique dynamically adjusts the voxel grid size according to the geometric complexity of the roadway structure. This facilitates efficient data simplification while effectively preserving essential geometric features. Concurrently, the dynamic radius filtering with hierarchical constraints optimizes dynamic neighborhood radius parameters through a multi-level constraint model, ensuring precise elimination of residual noise. Experimental results demonstrate that the proposed algorithm achieves a point cloud simplification rate exceeding 92%. Simultaneously, volume change rates and surface area change rates are effectively maintained below 3%. Comparative analysis against conventional voxel filtering, improved voxel filtering, and combined traditional methods indicates significant advantages of the proposed approach in both simplification efficiency and geometric fidelity. This method provides reliable technical support for data preprocessing in mine roadway deformation monitoring applications.
- 1
-
Study on mechanical properties and crack evolution of single fracture layered composite rock
Abstract:
Engineering disturbances during the mining process often lead to the formation of various fractures in rocks, which in turn affect their mechanical properties. This study employed indoor uniaxial compression tests, combined with XTDIC and acoustic emission monitoring systems, to systematically investigate the influence of fracture location, dip angle, and rock layer combination on the mechanical behavior and failure mode of single-fractured layered composite rock samples. The research findings indicate: (1) The peak stress of fractured rock samples increases with the increase of dip angle, gradually rising from 13.19 to 25.34 MPa to 33.89 to 42.99 MPa, while the elastic modulus shows a non-monotonic trend of first increasing and then decreasing. The deterioration coefficient continuously decreases with the increase of dip angle, from 0.45 to 0.66 to 0.06 to 0.13, and the strength deterioration effect of fractures on sandstone is more significant than that on limestone. (2) The fracture location dominates the evolution of the failure mode: when the fracture is located at the upper part of the rock sample, tensile failure is dominant; when it is located in the middle, the failure mode is regulated by the dip angle, with tensile failure still being dominant at low dip angles, but transitioning to tensile-shear mixed failure at high dip angles. (3) The analysis of acoustic emission parameters (RA/AF values) shows that at low dip angles, the first appearing cracks are mainly tensile cracks, accounting for 81.69% to 88.41%. As the dip angle increases, the proportion of shear cracks rises, and the failure mode gradually transitions from tensile failure to a mode with more tensile and less shear, until ultimately forming a tensile-shear mixed failure with tensile cracks accounting for 56.33% to 62.73%.
- 1
-
Anomaly Detection of Mining Equipment by Integrating BiLSTM and Improved Subtractive Average Optimizer
Abstract:
This study proposes a mining equipment anomaly detection model based on bidirectional long short memory network and improved subtraction average optimizer, aiming to solve the problems of low efficiency and poor accuracy of traditional equipment anomaly detection methods. This model dynamically weights key features by introducing attention mechanism, combines convolutional neural network to extract local temporal features, and uses guided regularized random forest for feature selection to reduce data dimensionality and noise interference. Furthermore, the improved subtractive averaging optimizer utilizes chaotic mapping initialization and golden sine step size adjustment to enhance the convergence speed and stability of the model.t. The results show that on the multi-sensor time series dataset of mining equipment and the fault simulation dataset of mining machinery, the accuracy rate of the proposed model reaches 94.17% and 95.48% respectively, and the F1 scores are 93.02% and 95.57% respectively, which is superior to the existing mainstream detection models. In the actual application test, the detection accuracy of the model has been improved to 97.32%, with an average detection time of only 0.39 seconds, verifying its efficiency and practicality. Research has shown that the model can provide high-precision and high-efficiency solutions for abnormal detection of mining equipment, which is of great significance for ensuring the safety of mining production.
- 1
-
Fault diagnosis method of scraper conveyor bearing based on double branch convolutional neural network
Abstract:
As a key equipment in coal mine underground transportation systems, the bearings of mining scraper conveyors are prone to failure under extreme operating conditions such as high temperature, high impact load, dust pollution, and long-term operation. However, under complex operating conditions and multiple failure modes, existing fault diagnosis methods still face many challenges in terms of feature extraction and classification accuracy. To this end, this paper proposes a bearing fault diagnosis method based on a dual-branch neural network. Firstly, the one-dimensional vibration signal is converted into a two-dimensional time-frequency map using continuous wavelet transform to enrich the time-frequency features of the input data. Subsequently, a dual-branch neural network architecture is constructed, where one branch is based on a dilated convolution residual module to enhance local feature extraction capability, and the other branch combines a global attention mechanism to optimize the learning of global features. Finally, the diagnostic ability of the model is improved through feature fusion. Experimental verification is conducted on the CWRU bearing dataset and the PU bearing dataset, and the results show that the accuracy of this method in fault diagnosis reaches 99.78% and 97.94%, respectively. The overall performance is superior to that of comparative models such as DCRB-CNN, GAM-CNN, and GAM-ResNet, demonstrating significant diagnostic capability and good generalization effect. In addition, this paper also conducts bearing fault diagnosis experiments using coal mine field data, further verifying the practicality and engineering deployment value of the proposed method under strong noise and non-stationary operating conditions. This research provides an efficient and reliable deep learning solution for intelligent fault diagnosis of complex coal mine equipment such as scraper conveyors.
- 1
-
Research on Optimization of Stope Structure Parameters Based on Artificial Intelligence Algorithms Combined with Numerical Simulation
Abstract:
Rational selection of stope structure parameters is crucial for maintaining stope stability and enhancing mining economic efficiency. This study? addresses the limitations of conventional empirical analogy methods (prone to subjective evaluation biases) and standalone numerical simulation approaches (complex modeling procedures and high computational workloads) in stope parameter optimization. We propose an artificial intelligence-based stope parameter optimization method integrating Dung Beetle Optimizer (DBO), Multilayer Perceptron (MLP), and Support Vector Machine (SVM). The DBO algorithm enhances MLP and SVM performance, while the SVM-MLP hybrid framework mitigates the risk of MLP converging to local optima. Utilizing stope parameter datasets and stability evaluation grades from representative mines, the DBO-MLP-SVM model was trained. A case study of a limestone mine in southwestern China demonstrated that stope stability classification results from the DBO-MLP-SVM model indicated instability at 7m and stability above 8m. FLAC3D numerical simulations further validated these findings by analyzing stope displacement, pillar deformation, and surface subsidence, confirming the critical pillar dimension threshold of 8m. The consistency between AI model predictions and numerical simulation results underscores the method's reliability. Finally, through quantitative comparison with traditional methods, the stope production capacity achieved by intelligent collaborative optimization reached 167.44 t/d, representing a 51.80% increase in production capacity. With comparable loss and dilution rates, this approach effectively balanced the dual objectives of production efficiency and safety assurance, further validating the superiority of the model. This research provides a novel hybrid intelligent framework for data-driven stope parameter optimization in mining engineering.
- 1
-
Multi-feature prediction of water inflow in mine extracting face based on deep learning modeling
Abstract:
During coal mining extracting face operations, disturbance induced in aquifers can readily lead to increased water inflow at the working face, threatening mine safety. Timely advanced water inflow prediction and evaluation of results can effectively prevent water hazard incidents. Consequently, building upon a summary and analysis of current water inflow prediction methods, this study investigates a multi-feature prediction method for working face water inflow based on deep learning models. The main procedures are as follows: By integrating water inflow data characteristics and on-site conditions, "dual aquifer water levels + maximum height of microseismic events" were selected as the feature dataset. A multi-feature prediction model based on VMD-iCHOA-GRU was established for working face water inflow. Comparative models were also configured. Furthermore, validation tests were conducted under scenarios involving different feature combinations, single-target conditions, and diverse extracting face datasets to verify the multi-feature model's efficacy. Results demonstrate that the VMD-iCHOA-GRU model achieved MAE, RMSE, and MAPE values of 53.56 m3/d, 62.98 m3/d, and 3.1% respectively, outperforming all comparative models with highest prediction accuracy. The multi-feature model consistently surpassed single-factor, single-feature, and dual-feature models in accuracy. Notably, features exhibiting stronger correlation with research targets demonstrated greater advantages in enhancing prediction accuracy. Additionally, the model maintained robust performance across different extracting face datasets, confirming its relative stability and extensibility. This research provides novel methodologies for working face water inflow prediction, offering significant scientific guidance and reference value for mine water prevention and control, thereby safeguarding mine production safety.
- 1
-
Flotation foam size extraction method based on improved YOLOv11n-seg
Abstract:
Aiming at the difficulty of foam size extraction in flotation process, a new flotation foam size extraction method improved YOLOv11n seg was proposed. Firstly, a Cross-Scale Feature Fusion Module (CCFM) is introduced to refine the neck structure, enhancing the model's adaptability to scale variations and its detection capability for small-scale objects. Secondly, a Mixed Local Channel Attention (MLCA) mechanism is added to integrate channel information, spatial information, and local information, thereby enhancing the network's expressive power. Finally, the Unified-IOU loss function is introduced to dynamically shift the model's attention from low-quality prediction boxes to high-quality ones, balancing training speed and detection accuracy. Experimental results show that, compared to traditional methods such as the watershed algorithm and deep learning-based Mask R-CNN, the proposed method exhibits significant advantages in segmentation accuracy and real-time performance. Compared to the baseline model YOLOv11n-seg, the optimized model achieves a 1.5% and 5.3% improvement in precision mAP@0.5 and mAP@0.5:0.95, respectively, with a 5.1% increase in recall rate, a 11.8% reduction in computation, and a 32.1% decrease in parameter count. This method offers faster detection speed and higher detection accuracy, meeting the requirements for precise extraction of flotation foam size.
- 1
-
Simulation study of adsorption and diffusion of CH4 and CO2 in coal molecular structures at different temperatures and moisture contents
Abstract:
We employed the grand canonical ensemble Monte Carlo method and molecular dynamics simulations to study the adsorption and diffusion processes of CH? and CO? in a coal molecular structural model under different temperature, pressure and moisture content conditions, in order to investigate the adsorption and diffusion characteristics of CH? and CO? in coals. The results indicate the following: (1) As temperature increases or moisture content rises, the adsorption amounts of both gases decrease to a certain extent; however, CO? exhibits superior adsorption and diffusion capabilities compared to CH?; (2) As pressure increases, the adsorption amounts of both gases increase, but they tend towards saturation and exhibit typical saturated adsorption characteristics; (3) Langmuir model fitting results show that increases in temperature or moisture content lead to decreases in the adsorption parameters a and b. The CO? parameters remain higher than the CH? parameters, indicating a stronger adsorption affinity in coal. (4) Diffusion patterns show that an increase in temperature significantly enhances the kinetic energy of gas molecules, reducing local enrichment in coals and improving diffusion performance. The mean square displacement of CO? at all temperatures is greater than that of CH?, indicating stronger diffusion ability and a more uniform spatial distribution. (5) As the moisture content increases, the average mass density of both gases decreases in the coal molecular structure model. Although the presence of water molecules does not alter the overall trend of the gas adsorption curve, it significantly reduces the adsorption saturation point of the gases; (6) When the moisture content reaches 6.55%, gas diffusion behaviour is significantly inhibited. Water molecules fill the pores and interact with coal molecules, limiting gas diffusion pathways, reducing gas migration extent, and thereby restricting diffusion rates. The diffusion coefficients for CH? and CO? decrease to 0.063-8 m2/s and 1.33×10-8 m2/s, respectively. This study provides a theoretical basis for enhancing coalbed methane recovery rates and optimising CO? sequestration strategies.
- 1
-
Optimization of unmanned truck scheduling in large surface coal mine based on digital twin simulation
Abstract:
Aiming at the problems of poor scheduling scheme，low utilization rate and high cost of unmanned trucks in large surface coal mines，an optimization method based on digital twin simulation is proposed，a digital twin system framework for unmanned mining trucks is constructed，and a digital twin simulation model is built with the help of AnyLogic software to realize real-time mapping between physical and virtual spaces. For the multi-objective and multi-constraint unmanned truck scheduling optimization problem，a mathematical model with the objectives of minimizing the transportation cost，minimizing the total transportation time，and maximizing the truck utilization is established，and the Quantum Enhanced Particle Swarm Optimization Algorithm (QIPSO) is designed to solve the problem. Validated by an example of a surface coal mine in Xinjiang，the results show that compared with the traditional particle swarm algorithm，improved particle swarm algorithm and genetic algorithm，the QIPSO algorithm reduces the maximum completion time，total transportation cost by 11.34% and 10.62% respectively，while increasing truck utilization by 9.14%，and has a faster convergence speed and better stability. The digital twin scheduling scheme shortens the task completion time by 73 minutes compared with the traditional scheme，effectively improves the transportation efficiency，and provides a feasible technical path and methodological support for the intelligent scheduling of unmanned trucks in surface coal mines.
- 1
-
Cost Analysis Study of Medium-sized Lead-Zinc Mines Based on the AHP Model
Abstract:
To effectively manage and control mine costs and guide enterprises in reducing costs and increasing efficiency, this paper centers on a "complete cost" target system. Using AHP,statistical analysis, graphical methods, and case studies, it systematically compares, studies, and analyzes the complete costs of four medium-sized lead-zinc mines both domestically and internationally. The following conclusions are drawn: Mining method is crucial for controlling full costs；The complete cost ratio is in turn the production cost, taxes and surcharges, administrative expenses, operating expenses, and financial expenses; it has a scale effect, the larger the scale, the lower the unit cost of the product; for projects of the same scale, the complete cost of mines is higher than that of domestic mines; for medium-sized lead-zinc mines, the complete cost of lead is between 10,000 and 17,000 yuan/t metal, and the complete cost of zinc is between 6,000 and 12,000 yuan/t metal. The above conclusion is of practical guiding significance to cost control in the actual production of lead-zinc mines.
- 1
-
Development and Application of an Information System for the Dual Prevention Mechanism in Non-Coal Underground Mines
Abstract:
In order to meet the needs of the current information system construction for the dual prevention mechanism of risk grading control and hidden danger investigation and governance in non coal mines, based on the process of dual prevention mechanism construction, a set of "non coal underground mine dual prevention mechanism information system" based on B/S architecture has been developed using a "one platform, two ends, and three levels" business architecture. The data collaboration of "platform+terminal" is used to achieve the refinement and intelligence of the entire process of dual prevention mechanism construction and management in mining enterprises, effectively promoting the transparency of risk control and the flattening of hidden danger governance. At the same time, the system was promoted and applied in pilot mines, and the results showed that the system significantly improved the efficiency of mine safety management. On a more comprehensive basis, hidden danger investigation and governance increased work efficiency by 90% and governance efficiency by 30%. It promoted the implementation of the safety responsibility system for all employees, promoted the digital transformation of safety management, and provided strong support for the standardized construction of safety production in non coal mining enterprises.
- 1
-
Stability Assessment of Adjacent Power Transmission Tower Foundations Affected by New Mine Mining
Abstract:
A newly constructed open-pit mine has transmission tower foundations for the Yiquan-Yi Line and Jinzhong HVDC Line located approximately 300 meters away on both sides, where slope excavation may induce tilting and subsidence of the power transmission tower foundations, or foundation damage from rockfall impacts. Stereographic projection, limit equilibrium method, and finite element numerical simulation were applied to qualitatively and quantitatively analyze the excavation disturbance zone, slope stability, and rockfall effects on power transmission tower foundations. Analysis results indicate stable slopes at final excavation boundaries, with power tower foundations positioned 69.2–192.9 meters beyond the disturbance zone and outside minimum-safety-factor failure surfaces. Rockfalls from the pit crest primarily roll down into surrounding gullies, with no rocks reaching the vicinity of the power transmission tower foundations on either side of the open pit, which are also situated at higher elevations. The study concludes that mining operations at this new mine will not affect the power transmission tower foundations adjacent to the pit.
- 1
-
Research On Failure Precursor Of Soaked Coal Based On Dominant Acoustic Emission Signal Screening
Abstract:
To improve the accuracy of identifying failure precursors in water?soaked coal, uniaxial compression and synchronous acoustic emission?(AE) experiments were performed on coal specimens in the natural state and after 120?h of water immersion, addressing the problem that a high proportion of low-energy AE events masks high-energy information during fracturing. An AE signal screening method coupling energy contribution ratio with damage stress was established to extract dominant signals and analyse their precursory characteristics. Results show that (1) water immersion markedly reduces coal compressive strength, promotes multidirectional crack propagation, and intensifies ultimate failure; (2) AE count and cumulative AE count during fracturing serve as key parameters for recognising impending failure, but their reliability must be judged in conjunction with specific fracturing stages; (3) the proposed method efficiently extracts dominant signals during the fracture of soaked coal, yielding lower energy thresholds and higher dominant-signal proportions than in natural coal; (4) the extracted dominant signals correspond closely to the precursory characteristics of soaked?coal failure and provide an effective basis for engineering stability prediction.
- 1
-
Optimization of double reverse flotation process of phosphate rock and study on removal mechanism of potassium feldspar
Abstract:
To enhance the utilization value of medium-grade siliceous-calcareous phosphate rock resources in the Yichang area, Hubei Province, characterized by fluorapatite as the primary valuable mineral and potassium feldspar, dolomite, and quartz as the main gangue minerals (raw ore: P2O5 grade 23.27%, Al2O3 content 4.33%, MgO content 1.56%), a double reverse flotation process was employed .Systematic investigations were conducted, including optimization tests for grinding fineness, dosage tests for collectors (H-1, KM-6) and auxiliary reagents (phosphoric acid, HF-959), combined with contact angle measurement, Zeta potential analysis, and Fourier transform infrared spectroscopy (FTIR) to elucidate the flotation mechanism. The results showed that?? under the optimized grinding fineness of 81% passing 75 μm, a closed-circuit flowsheet comprising "one roughing and two scavenging stages for silica removal" and "one roughing and one scavenging stage for magnesia removal" yielded a high-quality phosphate concentrate. This concentrate assayed 32.20% P2O5 with a recovery of 81.20%, where the Al2O3 and MgO contents were reduced to 2.02% (a decrease of 53.35%) and 0.62% (a decrease of 60.26%), respectively, effectively achieving the separation of apatite from gangue minerals like potassium feldspar and dolomite. The mechanism study revealed that collector H-1 selectively acts on the surface of potassium feldspar primarily through physical adsorption, significantly enhancing its hydrophobicity, which is the key to the efficient removal of potassium feldspar.
- 1
-
Research on the Thermal Runaway Characteristics of Lithium Iron Phosphate Batteries for Mining during Overcharging
Abstract:
With the wide application of lithium-ion batteries in underground mines, the safety issue of mining batteries has become increasingly prominent. In this paper, overcharge tests were performed on 200Ah LiFePO4/C battery cells and battery modules at different rates (0.5C, 1C, 1.5C) to study the thermal runaway characteristics of large-capacity batteries used in mining. The results show that the thermal runaway behavior of the lithium-ion batteries is divided into three stages: battery expansion, slow flue gas injection, violent flue gas injection-subsequent natural cooling, etc. As C-rate increases, the overcharged capacity required in each stage gradually decreases. The temperature after thermal runaway of the battery can reach up to more than 400℃, and the maximum temperature in the battery module experiment is significantly higher than that in the battery cell experiment. High temperature will pose a severe challenge to the safety of underground mines, and corresponding cooling and protective measures need to be taken. The thermal effect of overcharged batteries in the battery module does not cause thermal runaway reactions of adjacent batteries. The critical conditions for the thermal runaway chain reaction of mining batteries still need further study.
- 1
-
Deformation Characteristics and Reinforcement Techniques of High Stress Tunnels in Ultra Deep Metal Mines under Disturbance
Abstract:
As mining enters deeper areas, it faces more complex engineering and technical challenges. This article takes a high stress roadway in a certain ultra deep metal mine as the background, and uses methods such as in-situ stress testing and rock mechanics testing to determine its maximum principal stress value and engineering rock mass quality level. Based on the damage situation of the tunnel, deformation monitoring, borehole imaging, and ground pressure monitoring methods are used to analyze the deformation characteristics of the tunnel and analyze its failure mechanism. Based on the characteristics of the project, such as a burial depth of over a kilometer, developed rock bedding, and susceptibility to weathering after exposure, a combined support form is adopted, which includes initial spraying to seal the surrounding rock, active support with anchor nets, passive support with U-shaped steel arches, and re spraying to form a whole. This reinforcement scheme not only fully utilizes the load-bearing capacity of the roadway rock mass itself, but also limits the development of the rock fracture zone and plastic zone. According to monitoring equipment, with the construction of systematic support, the integrity of the surrounding rock of the tunnel has been greatly improved, and the rock mass has entered a relatively stable state, providing experience for the support of similar deep mine tunnels.
- 1
-
Research on intelligent control system of multi-face blasting process under mine
Abstract:
Based on the actual engineering scenario of separated drilling and blasting operations at an iron mine, this study investigates a series of issues arising from this operational separation. Key problems identified include: challenging organizational coordination, lagging information transfer between processes, information silos in blasting operations, frequent risk occurrences, and high production costs. To effectively address these challenges and enhance mining efficiency, the research employs major blasting accident case analyses and fault tree risk assessment methodologies. Integrating the mine’s practical requirements, a conceptual framework for intelligent management of multi-workface blasting operations in underground mining is proposed. Following this framework, an intelligent management system is designed with multifunctional capabilities: real-time interaction and management of blasting information across multiple working faces at different levels, task allocation for blasting operations, precision management of explosive materials, and multi-tier personnel control. The system is primarily developed using Vue and Django frameworks. Through comprehensive testing and practical deployment, the developed intelligent blasting management system has effectively resolved the mine’s operational incoordination between drilling and blasting processes.
- 1
-
Characteristics of Shaft Wall Failure in Deep Vertical Shafts Passing Through Broken Rock Mass and Reinforcement Technology Research
Abstract:
Deep vertical shafts are critical infrastructure for deep resource development, and their stability is essential for ensuring safe and efficient mining operations. The stability of shaft walls in fractured rock masses is a key issue in deep mining. This study used the bond block model (BBM) in discrete element software to build a 3D numerical model of the vertical shaft in the Xiling mining area of the Sanshanda Gold Mine. The research analyzed the damage and fracture characteristics of shaft walls at burial depths from 1600 meters to 2500 meters and proposed support and reinforcement schemes for shaft walls in high-stress and fractured rock environments.The results indicate that in high-stress conditions, the deformation and fracture of surrounding rock around deep shaft walls are influenced by horizontal in-situ stress. As the burial depth increases, the maximum displacement and deformation range of the surrounding rock increase. The displacement changes in the direction of the maximum principal stress are significant, while the areas of minimum principal stress are the main zones of shear stress distribution. Fractured rock masses increase the mechanical complexity of the surrounding rock. The displacement and stress distribution within fractured zones are closely related to support conditions. The dynamic effects of fractured rock masses can lead to rock block spalling and surrounding rock failure. Grouted anchor bolts can effectively improve the stress state of support structures, disperse concentrated stresses in the surrounding rock, and reduce shaft wall displacement and crack propagation. Reasonable support and reinforcement measures can effectively control the dynamic effects of fractured rock masses and mitigate the risk of shaft wall failure.
- 1
-
Research on Controlled Blasting Technology and Fragmentation Prediction for Ore-Rock Separation in Las Bambas Open-pit Mine
Abstract:
The ore rock of Las Bambas copper mine is interlaced, the hardness of each area is different, and the lithology is rich. It is difficult to apply single blasting parameters to complex geological conditions. In order to ensure the control of ore fragmentation and low loss in the process of mine blasting, the technology of ore-rock separation control blasting and fragmentation prediction in open-pit bench blasting are studied in depth. The rock mass index RMI is used to divide the rock mass blastability, and the ore-rock boundary of in-situ stacking blasting and throwing blasting is put forward to control the ore-rock boundary, and the multi-point initiation scheme and dense empty hole scheme with different hole network parameters are formed. Based on the XGboost model, the blasting data of Ferrobamba mining area are trained, and the blasting fragmentation of 25 groups of sample data is predicted and verified by field test. The results show that the multi-point initiation scheme with different hole network parameters is adopted, and the hole depth is 16.5 m. Under the condition of hole network parameters of 9.0 m × 8.0 m in rock area and 6.5 m × 5.5 m in ore area, obvious ore-rock boundary ditch line is formed after blasting, and ore and rock are piled up respectively. The characteristic parameter D80 of lumpiness distribution is 127 mm, which is close to the predicted value of 124 mm, and the error is only about 2.36 %. Among them, the proportion of lumpiness 25.6 mm is 36.7 %, which meets the requirements of the concentrator.
- 1
-
Numerical Simulation Analysis of Dust Emission Law in 0pen-pit Stope of Qidashan Mine
Abstract:
In view of the unclear mechanism of dust emission in open-pit mines, taking Qidashan Open-pit Mine as the engineering background, the influence of wind speed, wind direction, particle size and dust source location on dust dispersion rate was analyzed by numerical simulation method, and the temporal and spatial distribution characteristics of dust under multi-dust source conditions were discussed. Based on the field meteorological data, a three-dimensional flow field model of Qidashan stope was constructed, and the dust dispersion rate was simulated and analyzed under different working conditions. The results show that the particle size is the most important factor affecting the dust dispersion rate, and the smaller the particle size, the higher the dispersion rate. The second is the wind speed, and the wind speed has a significant effect on the dust with a particle size greater than 30 μm. Dust source location and wind direction have relatively small influence on dust dispersion rate. In addition, under the condition of multiple dust sources, dust accumulates in the stope and dissipates along the wind direction with the increase of continuous dust production time. After the dust production is stopped, the dust concentration gradually decreases, and the dust dissipation speed of different dust source points varies due to the location difference. The bottom area of the stope is affected by topography and airflow, and the PM2.5 concentration increases-decreases-increases with the increase of the depth of the stope.Finally, according to the above rules, relevant measures and suggestions are proposed for dust prevention in the production of Qidashan Open-pit stope.
- 1
-
Surrounding Rock Load of Rectangular Roadway in Solid Coal Considering Horizontal Stress
Abstract:
To address the damage mechanisms and control issues of the surrounding rock in deep-buried solid coal rectangular roadways beneath thick loose layers and thin bedrock overburden, the influence of horizontal stress on the surrounding rock load of this kind of roadway is investigated through field investigation of engineering examples, numerical simulation, theoretical derivation and case application. Using the Guotun coal mine as a case study, the damage characteristics of solid coal rectangular roadways under such geological conditions were elucidated. Based on the in-situ stress characteristics of deep buried roadway, the arch axis equation of the balanced arch considering the horizontal tectonic stress was derived based on the balance of forces and moments, and the calculation method of the surrounding rock load of rectangular roadway based on the improved model of the balanced arch was proposed and programmed, which perfected the theory of the balanced arch analysis. Subsequently, the improved model of balanced arch was verified and analyzed by two arithmetic cases and engineering examples. Finally, the influencing factors of the failure height of vault and roof load were studied. The results of the study are an important guide to the bolt/anchor cable support of this kind of roadway.
- 1
-
Study on the inhibition of microfine-grained hematite by a new potassium ionized starch
Abstract:
Abstract: Poor-grade hematite ore, characterized by low grade and fine grain size, is prone to over-grinding during grinding operations, resulting in a large amount of fine-grained minerals. These fine-grained minerals, due to their small particle size and large specific surface area, exhibit covering and surface adsorption competition effects during flotation, significantly weakening the selective adsorption capacity of flotation reagents. This study addresses the challenge of selective inhibition during the separation of fine-grained hematite by developing a novel K+ starch inhibitor. Based on flotation tests of quartz and pure hematite minerals, combined with contact angle measurements, Zeta potential analysis, Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDS) detection and analysis, the study systematically elucidates the inhibition mechanism of the novel K+ starch on fine-grained hematite. Experimental results indicate that when the K+ starch dosage is 150 mg·L-1, the activator CaO dosage is 100 mg·L-1, and the collector sodium oleate dosage is 200 mg·L-1, compared to traditional corn starch, the quartz recovery rate increases by 4.00% to 83.50%, while the hematite recovery rate decreases to 15.85%; When flotation mixed magnetic concentrate was processed, the concentrate grade and recovery rate were increased by 7.28% and 5.30%, respectively, compared to corn starch. Mechanistic analysis indicated that when K+ starch adsorbed onto the surface of hematite, it combined with O2? to form K—O?, reducing the surface contact angle of hematite to 22.31° and forming a hydrophilic film, thereby achieving selective inhibition. This study provides a green and environmentally friendly design concept and theoretical basis for the efficient separation of fine-grained hematite using a new type of inhibitor.
- 1
-
Research on the Laws of Roof Caving Impact Vibration and Vibration Velocity Determination Methods in Caving Mining Stopes
Abstract:
Aiming at the problem that the impact vibration caused by roof collapse in caving mining threatens the stability of the stope, a physical simulation test is designed based on the mechanism of caving impact vibration and the similarity law of physical simulation. The relationship between the vibration velocity of the collapse impact and five factors, namely the falling height of the collapse body, the amount of one collapse, the void ratio of the buffer cushion layer, the thickness of the buffer cushion layer, and the distance of the measurement point, was studied through 28 sets of data experiments. The test results show that: The vibration velocity of the collapse impact is positively correlated with the height of the falling body and the amount of a single collapse, and negatively correlated with the thickness of the buffer cushion layer and the distance of the measurement point. However, both excessive and insufficient void ratio of the buffer cushion layer are not conducive to the absorption of impact energy. The order of the correlation degree between the vibration velocity of the collapse impact and each factor is the distance of the measurement point, the amount of a single collapse, the height of the falling body, the thickness of the cushion layer, and the void ratio of the cushion layer. Finally, based on the test results and the calculation method of blasting vibration velocity, an empirical formula that can be used to measure the vibration velocity of caving impact was constructed and applied to the West No.2 mining area of Longshou Mine in Jinchuan. It was calculated that the maximum vibration velocities that could be generated when the roof of the caving method mining area caved down at 1595m, 1554m and 1494m were 7.2cm/s, 6.4cm/s and 3.2cm/s respectively. The maximum vibration velocity values measured at each level by on-site blasting vibration monitoring were 1.21cm/s, 0.26 cm/s, and 0.09cm/s respectively, which proved the reliability of the measurement method proposed by the research institute. The research results can provide theoretical basis and practical guidance for the prevention and control of roof fall and impact disasters in underground mines.
- 1
-
Impact of Stope Width and Stoping Sequence on Pillar Stability of Panel
Abstract:
To study the influence of stope width and stoping sequence on the bearing capacity of the panel pillar, taking the open stope with subsequent filling method in the Sijiaying mine as the background, based on three stope widths and three mining sequence schemes of the panel mining, the stress response characteristics and deformation failure characteristics inside the panel pillar were investigated. Finally, the mining plan for the mining area of the mine was determined, with a width of 20 meters and the mining sequence moving from the center to both sides. The research results show that: (1) the stope width and the stoping sequence in the panel jointly affect the stress response characteristics inside the panel pillar. Under different stoping sequences of the stope in the panel, with the increase of the stope width, both the maximum principal stress and the minimum compressive stress inside the panel pillar show an increasing trend; (2) the width of the stope and the stoping sequence in the panel also jointly affect the deformation and failure characteristics of the inter-disk column. Under the same mining sequence, both the displacement and the volume of the plastic zone within the panel pillar increase with the increase of the stope width; (3) under the same stope width, the change of the displacement and the volume of the plastic zone within the panel pillar both show a sequence of changes from high to low, that is "one side to the other side" , "both sides to the center" , and "center to both sides". The research results have important guiding value for the mine production.
- 1
-
Study on Goaf Treatment and Mining Scheme of Xiaohanzhuang Iron Mine from Caving to Backfilling
Abstract:
The sublevel caving method is adopted in Xiaohanzhuang iron mine. Due to the lack of forced caving of the roof, with the stope extending to the depth and insufficient overburden, the roof of the goaf and the original room-and-pillar method point pillars in the -40m sublevel collapsed, causing great hidden dangers to the safe mining of the stope. The Mathews diagram method and numerical simulation analysis on the stability of the goaf show that there is a possibility of large-area roof collapse. Therefore, it is recommended that the -72m middle section should not be mined and corresponding blocking should be completed, and the -90m middle section should be mined by the backfilling method. Combined with the ore body mining conditions and mine requirements, three technically feasible mining schemes are proposed: sublevel open stoping post-backfilling method, panel mechanized upward horizontal slicing backfilling method, and upward horizontal slicing backfilling method perpendicular to the ore body strike. Comprehensively considering the production technical indicators and mining safety, the panel mechanized upward horizontal slicing backfilling method is recommended for the mine. After switching from the caving method to the backfilling method, the dilution and loss indexes are significantly improved, the annual output value meets the production demand, and within the remaining service life, the backfilling method creates 49.4767 million yuan more efficiency than the caving method.
- 1
-
Research on the Development and Application of an Optimal Utilization Decision-Making Model for Granite
Abstract:
In the mining of building materials, issues such as high-quality materials being underutilized and mixed use of high- and low-quality materials have led to inconsistent product quality, reducing product value and resulting in resource waste. As a major producer and exporter of stone materials, China faces the urgent challenge of optimizing the planning and utilization of these resources. To address this, this study uses granite as an example to establish a multi-dimensional comprehensive evaluation system for the optimal use of granite, encompassing four primary indicators—aesthetic quality/chemical properties, physical and mechanical properties, economic benefits, and ecological benefits—and 19 secondary indicators. Additionally, a decision-making model for the optimal use of granite was constructed, integrating multi-dimensional factors such as physical and chemical properties, economic benefits, and environmental impact. To validate the practicality and reliability of the corresponding decision-making model, Yunfu granite, Luotian granite, and Gold Ma granite were used as examples. The optimal uses of Yunfu granite, Luotian granite, and Gold Ma granite were determined to be natural stone for squares (roads or sidewalks), natural stone slabs for furniture, and gravel for construction, respectively. The results were further compared and analyzed with the VIKOR method and the grey correlation degree method, demonstrating the feasibility of the TOPSIS decision-making model. Additionally, sensitivity analysis validated that the TOPSIS decision-making model proposed in this study has good stability in purpose ranking. This study provides a scientific basis for the optimal use of granite. The constructed decision-making model and developed decision-making analysis tools have broad application prospects and can effectively support the optimized allocation of granite products.
- 1
-
Study on Stability of Disturbed Wellbore in Overlapped Resources Recovery
Abstract:
Based on an iron mine in Anhui Province, the influence of overburden resource exploitation on shaft disturbance was studied. Geological investigation and rock mechanics parameter analysis were carried out. Two kinds of overburden resource exploitation schemes were determined by empirical analogy method. Finally, the stress state around the shaft under horizontal stress disturbance was analyzed by using the stress concentration principle around the thin circular hole. The results show that two mining schemes of overburden resources could be adopted. In order to ensure the safety of the shaft, one mining step and two mining steps are preferred. When the stress around the shaft is within 2 times of the original rock stress, the shaft is in a stable state. The research results provide technical support for the safe mining of overburden resources.
- 1
-
In-situ leaching slope stability evaluation of ionic rare earth ore based on game theory-cloud model
Abstract:
The in-situ leaching process of ionic rare earth ores can easily cause slope instability, which brings risks to the environment and public safety. The traditional stability criterion method cannot quantify the uncertainty of dynamic multi-field coupling, and the previous weight fusion methods have problems such as static weighting and host-guest bias. Therefore, this study, based on the selection principles of core indicators of uniqueness and purpose, constructed an evaluation system including geomechanical parameters,the leaching process, and hydrometeorological parameters.The game theory is used to make reasonable use of expert experience and the objective weights of key indicators to realize the collaborative optimization of subjective and objective weights, and then the cloud model is introduced to express the stability membership degree of slope, and the stochastic ambiguity of parameter values is described by expectation, entropy and superentropy parameters, which overcomes the shortcomings of the limit equilibrium method that is highly dependent on deterministic parameters, and effectively predicts the unstable state of slope in advance. Taking the rare earth mining area in southern Gannan as an example, the comprehensive stability scores of slope 1#, 2# and 3# are 74.8 (sub-unstable), 58.9 (relatively stable) and 99.3 (unstable), respectively, which are consistent with the results of on-site monitoring and improved AHP model, and can detect potential risks in advance compared with the traditional limit equilibrium method. Through the comparison and analysis with other methods, it is proved that the discriminant results are reliable, and the model has high risk sensitivity, which provides a new theoretical method for the dynamic control of the stability of ionic rare earth ore slopes, which has important practical significance.
- 1
-
UMTC-net design and engineering application for intelligent detection of cracks in underground mine tunnels
Abstract:
Aiming at the engineering problems such as insufficient crack detection accuracy and limited real-time performance in the complex geological environment of underground mine roadways, an Underground Mine Tunnel Crack-segmentation network (UMTC-net) integrating multi-scale feature perception and adaptive attention mechanism is proposed. This network realizes cross-scale feature extraction of crack images from local texture to global structure through hierarchical cascading Swin Transformer module groups, introduces the scaled cosine attention mechanism of logarithmic spatial relative position encoding to suppress abnormal pixel interference, and constructs an encoding and decoding framework based on patch dynamic merging/expansion. Solve the problems of ambiguous boundary positioning of fine cracks and high false detection rate in complex backgrounds by traditional methods. In the Crack500 dataset, the accuracy rate of UMTC-net reached 85.15%, the average intersection and union ratio was 85.78%, and the F1 value reached 83.27%. In the self-made experimental dataset, the accuracy rate was as high as 87.51%, the average intersect-union ratio was 79.98%, and the F1 value reached 86.95%, all of which were higher than those of the comparison methods. The results show that the research method has higher accuracy, average intersection and union ratio and F1 value in crack detection. Engineering deployment tests show that this model achieves a inference speed of 25.7 FPS on the RTX 3060 mobile graphics card and occupies only 5230MB of video memory, meeting the real-time and low power consumption requirements of portable detection devices. The research provides an efficient and accurate new solution for the detection of cracks in underground mine roadways, which is conducive to the timely discovery of potential safety hazards and ensures the production safety of mines and the stable operation of equipment.
- 1
-
Research on Safety Assessment Model for Open-pit Mine Blasting
Abstract:
In response to the difficulty in quantifying the qualitative evaluation of open-pit mine blasting safety, a open-pit mine blasting safety evaluation model based on combination weighting and interval approximation is proposed to improve the accuracy of the evaluation results. Firstly, based on the actual blasting engineering, 15 influencing factors were selected to construct a safety evaluation index system for open-pit mine blasting; Secondly, based on the idea of combinatorial weighting, the subjective and objective weights calculated by G1 method and improved CRITIC method are coupled to obtain balanced and reasonable comprehensive weights of indicators. Then, based on the interval number theory, the number of evaluation intervals for indicators is determined to avoid the problems of discontinuous data and easy loss and distortion of indicator information in traditional qualitative evaluation point estimation methods. By calculating the deviation distance of a single indicator and the comprehensive deviation distance, the blasting safety level is comprehensively judged; Finally, taking 5 open-pit mine blasting examples in Hunan Province as the research object, the combination weighting interval approximation method is applied for comprehensive analysis. The results showed that the blasting safety level of all 5 mines was "relatively safe", and the evaluation results were in line with reality, verifying the applicability of the model in the safety assessment of open-pit mine blasting.
- 1
-
Triaxial Mechanical Evolution Characteristics of Bedded Carbonaceous Slate under Chemical Erosion
Abstract:
To elucidate the influence of bedding angle and chemical corrosion under acidic environment on the mechanical behavior of carbonaceous slate, intact rock samples were collected from the sidewalls of a large-deformation roadway. Triaxial compression tests were performed on slate specimens subjected to different bedding angles and varying durations of acid-induced chemical corrosion. A continuous-discontinuous coupled numerical model based on the combined Discrete Element Method (DEM) was developed. Extended numerical analyses under additional loading conditions were conducted using an improved flexible membrane radial loading technique, with the analyses being validated by physical test results. The results indicate that: (1) Bedding angle significantly influences both the failure modes and peak strength of carbonaceous slate. The peak strength initially decreases and then increases as the angle between the bedding planes and the loading axis grows, reaching its minimum value at 15°~45°. This behavior is mainly attributed to wing crack propagation induced by shear slippage and localized stress concentration at these angles. (2) Acidic chemical corrosion markedly accelerates the structural degradation of the slate, with the peak strength decreasing by 36%~44% after 90 days of erosion, thereby confirming a negative correlation between chemical erosion and mechanical damage. (3) The DEM-based continuous-discontinuous coupled numerical model with flexible membrane radial loading accurately reproduces the triaxial mechanical response of the specimens under extended conditions, thereby providing a theoretical basis and data support for the stability evaluation and support design of deep roadways.
- 1
-
Multi-objective Optimization of Blasting Network Parameters in Open-pit Mine Based on TOPSIS - Numerical Simulation
Abstract:
To study the collaborative optimization of blasting effect and perforation blasting cost under complex working conditions in plateau open-pit mines, a multi-objective evaluation method based on TOPSIS ( Technique for Order Preference by Similarity to Ideal Solution ) method combined with numerical simulation verification is proposed. The range of hole network parameters and alternative schemes are determined based on the design parameters such as step height and slope angle based on the actual working conditions of a large plateau open-pit mine. The average fragmentation, bulk rate, non-uniformity coefficient of fragmentation and perforation blasting cost are selected as evaluation indexes. The Kuz-Ram blasting fragmentation model and the perforation blasting cost model are used to calculate the predicted value of the evaluation index of the alternatives, and the TOPSIS method is used to comprehensively evaluate and sort the alternatives. ANSYS LS-DYNA software is used to simulate the blasting damage of the optimal scheme and the alternatives. The results show that the distribution of strong crushing zone, fracture development zone and weak damage zone is relatively uniform in the blasting damage cloud map of the optimal scheme ( hole spacing 10 m×row spacing 8.5 m ), and the optimal control between blasting effect and cost is realized. The research results provide technical support for the optimization of blasting parameters in open-pit mines, and have certain practical promotion value and reference significance.
- 1
-
The phased mechanical response in the splitting process by dry and water-saturated siltstone
Abstract:
To investigate the phased mechanical response characteristics of the splitting process in dry and water-saturated siltstone. A systematic method for dividing the stress-strain curve during the rock splitting process is established to analyze the stage-specific response characteristics of stress and strain as well as their corresponding mechanical mechanisms by conducted the Brazilian splitting test. The results indicate that water significantly influences the stress evolution path and the strain development path during the Brazilian splitting process of siltstone. Specifically, the compaction stress, yield stress, peak stress and unloading stress of water-saturated samples decreased to 62.68%, 50.17%, 48.90% and 68.24% of those in dry samples, respectively. The proportion of stress in the compaction stage increased by 28.50%, while that in the elastic stage decreases by 19.60%. Additionally, the proportion of stress in the yield stage decreases by 41.35%, the stress in the failure stage attenuation decreases by 11.99%. The average values of compaction strain, yield strain, peak strain and unloading strain of water-saturated samples decrease by 4.41%, 19.26%, 20.17%, and 17.39% compared to dry samples, respectively. The proportion of strain in the compaction stage increases by 20.38%, whereas the proportions in the elastic and yield stages decrease by 29.64% and 36.93%, respectively. However, the failure stage increased by 347.73%. The water-saturated reatment process enhances the plastic behavior during the splitting process. Moreover, the water-saturated reatment reduces the bending energy index of siltstone by 73.77%, effectively mitigating the bursting liability.
- 1
-
Slope safety evaluation based on unascertained measure theory-finite element method
Abstract:
To ensure the safe operation of open-pit mines, it is necessary to conduct safety evaluations on the slopes to which they belong. This study takes the slope of a certain mine as the research object. By using the finite element method, a numerical calculation model of the slope is established to study the distribution laws of stress, displacement and plastic zone of the slope. The safety factors of the slope are analyzed respectively by methods such as the common strip division method and the Bishop method. The maximum displacement zone, plastic zone and minimum safety factor are all in the third-level slope. Therefore, Taking this level of slope as the evaluation object, the undetermined measure theory is adopted to construct a single-index measure function. The entropy weight method is used to determine the weight, and the distance discrimination method is adopted as the criterion for evaluating the safety level of the slope. The research results show that the slope evaluation grade of a certain open-pit mine is Grade II. Combined with the finite element analysis results, the evaluation results are consistent with the numerical simulation results, confirming that the slope of the mine is in a relatively stable and safe state. After reinforcement monitoring of the slope risk area, no slope accidents occurred, verifying the reliability and practicability of the combination of unascertained measure theory and finite element for slope safety evaluation.
- 1
-
Study on optimization of fan-shaped medium-length hole blasting parameters in deep iron mine filling stope
Abstract:
The fan-shaped medium-deep hole blasting method was used to break the rock in an iron mine. After entering the deep mining, due to the change of the mechanical properties of the ore and rock, the hole network parameters still use the old data, which leads to the problems of roof over-excavation, roof failure and high block rate in the mining process. Taking the horizontal stope from ? 360m to ? 450m as the engineering background, the theoretical value range of each blasting parameter is deduced according to the blasting fragmentation mechanism of ore rock and the theoretical formula of blasting parameters. Combined with the physical and mechanical properties of ore and rock and the performance parameters of explosives on site, the stope blasting model with different hole-bottom distance, explosive unit consumption and resistance line combination is constructed by using ANSYS / LSDYNA numerical simulation software. The prepost software and manager component are used for analytical calculation. The stress distribution characteristics of the mine roof under different blasting parameters were studied, and the Von Mises effective stress distribution law under four different hole bottom distances of 1.3m, 1.4m, 1.5m and 1.6m and four explosive unit consumptions of 2.13 kg / m3, 2.11 kg / m3, 2.09 kg / m3 and 2.07 kg / m3 was obtained. When the hole bottom distance is 1.4 m and the explosive unit consumption is 2.09 kg / m3, the Von Mises effective stress peak of the monitoring unit in the mining area is closest to the maximum dynamic tensile strength of the rock, which can fully break the ore and rock in the hole bottom area. The Von Mises effective stress peak of the roof monitoring unit did not reach the maximum dynamic tensile strength of the rock, and the roof was not damaged by the stress wave. When the resistance line is 1.6 m, the average dynamic tensile strength of the monitoring grid is 44.31 MPa, and the peak vibration velocity in the roof area is 22 cm / s. The ore rock can be fully broken and the roof stability is good, which does not exceed the allowable standard value of blasting vibration safety. Keywords: fan-shaped medium-long hole blasting; Hole bottom distance ; explosive unit consumption ; roof protection ; minimum resistance line
- 1
-
Study on Failure Evolution Characteristics and Stability of Slope Boundary Pillar of Mining in Transition from Open-Pit to Underground
Abstract:
In view of the situation that Sijiaying open-pit does not have the condition of plane boundary extension and needs to have a slope boundary pillar after underground mining, the stability of slope boundary pillar after underground mining is studied by using the gravity increase method, and the evolution characteristics and law of the stress field, displacement field and plastic zone of slope boundary pillar variation with the gravity acceleration are obtained. The results indicate that (1) under the initial gravity acceleration, a 40m thick slope boundary pillar can ensure the safety of underground mining and avoid the instability of the open-pit slope such as collapse and sliding phenomenon; (2) with the increase of gravity acceleration, the progressive instability failure of slope boundary pillar can be divided into four stages: stable, slight deformation, serious deformation and instability failure. The western slope of the open-pit within the exploration line N22~N26 in the mine is the most dangerous area where the slope occurs collapsing, slipping and other instability phenomena after the mine is transferred to underground mining; (3) affected by the unloading of underground mining, the maximum principal stress of slope boundary pillar is basically within 30MPa, while the minimum principal stress and its distribution range increase greatly. The value of tensile stress reaches more than 3MPa, which exceeds the tensile strength of rock mass and are easy to produce tensile failure of the pillar; (4) the displacement variation and the plastic zone expansion of the slope boundary pillar is consistent with the characteristics of the tensile stress, which extend from the slope foot to the top of the slope on the west side of the open-pit. When the gravity acceleration increases to 2 times the initial one, the plastic zone extends upward to the top of the slope in the slope boundary pillar on the west side within the exploration line of N22~N26, and the maximum displacement reaches 1.5m, resulting in the overall instability of the open-pit slope. The research findings play an important guiding role in the prevention and control of slope instability after the mine is transferred to underground mining.
- 1
-
Impact of Microbial Reclamation on Ecological Restoration and Soil Improvement of Grass-Shrub Combinations in Mine Dumps
Abstract:
Abstract: This study investigates the effects of different treatments on the vegetation index and photosynthetic characteristics of Amorpha fruticosa + Medicago sativa combination in a spoil dump, as well as their impacts on soil factors. Four treatments were implemented: control (CK), AMF inoculation, DSE inoculation, and AMF+DSE co-inoculation. Hyperspectral remote sensing data from UAVs were utilized for analysis, with plant and soil factors measured. The findings demonstrate a significant enhancement in net primary productivity from June to October, with the AMF+DSE treatment showing the most substantial improvement. Significant differences (P<0.05) in photosynthetic parameters were observed between the control and inoculation treatments for both Medicago sativa and Amorpha fruticosa. The AMF+DSE treatment yielded maximum values for transpiration rate and CO2 quantum efficiency in Amorpha fruticosa. From June to August, soil organic matter showed considerable increases in both AMF and dual inoculation treatments, with available phosphorus reaching its peak in the AMF treatment. Total nitrogen content was highest in the dual inoculation treatment. The pH values of inoculation treatments showed a marked decrease compared to June levels, while the control treatment exhibited a slight increase. Electrical conductivity reached its maximum in the dual inoculation treatment, significantly surpassing other treatments. Soil invertase activity peaked in the AMF treatment. The application of inoculation treatments in spoil dumps significantly enhances soil nutrient content and increases soil carbon sequestration potential.
- 1
-
The Ecological-Technological-Economic Synergistic Pathway for BuildingGreen Mining Clusters
Abstract:
This study employs a super-efficiency Slacks-Based Measure (SBM) model combined with the Global Malmquist-Luenberger (GML) index to measure the Green Total Factor Productivity (GTFP) of the mining industry, based on an ecological-technology-economic co-evolution perspective. It comprehensively evaluates the green development level of Xinjiang's mining industrial cluster, a representative ecologically fragile region. Results indicate that Xinjiang's mining GTFP lags behind the national average, with insufficient technological innovation capability remaining a key constraint. Quantitative analysis using the location entropy method reveals that Xinjiang's mineral resource industry exhibits characteristics of "high agglomeration, low green efficiency, and fragmented industrial chains," demonstrating a state of cluster "pseudo-prosperity." Empirical analysis via a Vector Autoregression (VAR) model elucidates the dynamic relationship between agglomeration degree, green development, and economic performance. Findings demonstrate that green benefits significantly influence mining cluster agglomeration, and the synergy between green benefits and industrial agglomeration constitutes the core driver for sustainable economic development, forming a positive feedback loop of "green technology → industrial agglomeration → economic efficiency enhancement." The study proposes establishing a "quadruple-helix" green development system centered on "ecological value-added, technology enablement, network synergy, and structural optimization" to provide countermeasures for the green, high-quality development of mining clusters.
- 1
-
Discussion on the application of Distributed Control System (DCS) in Zhuzailing Aggregate Plant
Abstract:
The Distributed Control System (DCS) was adopted to design and optimize the entire process of the Zhuzailing Aggregate Plant, including crushing, screening, sand making, and water circulation control, through hardware redundancy configuration, integration of Modbus communication protocol, and implementation of advanced control algorithms. The application effects in aspects such as material balance, equipment monitoring, and energy consumption management were analyzed. The actual application results show that this system significantly shortens the equipment start-stop time, reduces no-load energy consumption by 15%. The failure shutdown rate decreased by 30%, and the spare parts inventory turnover rate was optimized by 35%. The water consumption per ton of aggregate reduced from 3.2 m3 to 2.56 m3, saving 250,000 tons of water annually. The enterprise energy consumption achieved an 18% reduction comprehensively. The overall life cycle of equipment was extended by 3 to 5 years, resolving technical challenges such as signal transmission and circuit operation in high-dust environments, lightning strikes, or power fluctuations, thereby providing a technical reference for the intelligent transformation of industries such as aggregate processing.
- 1
-
Study on a Novel Cationic Collector for Reverse Flotation of Phosphate for Silica Removal
Abstract:
To effectively address the challenges of poor selectivity and limited applicability only under weakly alkaline environment of traditional cationic collectors for reverse flotation of silica removal from phosphate, a novel high-efficiency cationic collector SDTQ has been developed that is suitable for weakly acidic environments. Flotation tests were conducted using this reagent on a siliceous-magnesium phosphate from Guizhou Province. The results show that under the conditions of pH 6 and SDTQ dosage of 25 mg/L, the pure quartz sample showed a flotation recovery of approximately 100% while pure fluorapatite sample showed negligible floatability. With the sample of artificial mixture of quartz and fluorapatite, effective separation of fluorapatite from quartz was achieved under the flotation conditions of pH 6 and SDTQ dosage of 100 mg/L. Parametric flotation tests conducted with the actual phosphate sample, which was the concentrate from the magnesium removal flotation at pH 6, determined the optimum SDTQ dosage to be 1.1 kg/t. Under this reagent dosage, open-circuit flotation tests generated the separation performance of 35.38% P2O5 grade, 85.40% P2O5 recovery, and 5.53% acid insoluble (A.I.) content in the phosphate concentrate. Finally, a good performance of 35.49% P2O5 grade, 90.31% P2O5 recovery and 9.81% acid insoluble (A.I.) content in the concentrate was obtained from the closed-circuit flotation flowsheet of one rougher, one cleaner, and one scavenger. Compared with dodecylamine, SDTQ increased the grade of phosphate concentrate by 2.05 percentage points and the recovery by 10.02 percentage points. Zeta potential and contact angle measurements revealed that the key mechanism lies in SDTQ's selective adsorption on quartz surfaces through electrostatic interactions, which enhances the difference in hydrophobicity between quartz and fluorapatite, thereby enabling efficient silicon removal in reverse flotation of phosphate. The results of atomic force microscopy and infrared spectroscopy showed that the SDTQ collector acted on the surface of quartz in the form of physical adsorption by means of the synergistic effect of quaternary ammonium cationic groups and long-chain alkyl groups. SDTQ collector improved phosphate concentrate grade and reduced reagent costs, delivering dual economic and environmental benefits.
- 1
-
Experimental study on optimization of molybdenum bismuth sulfur beneficiation process in Huangshaping polymetallic beneficiation plant
Abstract:
In response to the difficulty of bismuth sulfur separation caused by excessive sodium sulfide suppression in the mixed flotation process at the Huangshaping polymetallic beneficiation plant, resulting in a large amount of low-grade bismuth ore storage, based on the study of the mineralogy of the original ore process, optimization research on the molybdenum bismuth sulfur beneficiation process was carried out. The research results indicate that the raw ore contains 0.061% molybdenum and 0.048% bismuth. Using the self-developed reagents B11 and CK-S from Changkuang Institute, a molybdenum concentrate with a Mo grade of 38.57% and a recovery rate of 45.10% was obtained through a process of grinding, iron removal, flotation of molybdenum bismuth and other floatable tailings for sulfur selection; Bismuth concentrate with a grade of 37.21% and a recovery rate of 68.38%. The tailings after molybdenum bismuth selection enter the sulfur selection operation, and after one coarse, three fine, and two scans, the sulfur concentrate S grade of 23.17% and the recovery rate of 32.66% are obtained as the beneficiation indicators. Compared with the original process flow, the new process has increased the bismuth grade from 4.86% to 37.21% and added sulfur product S grade of 23.17%, achieving efficient recovery of bismuth and sulfur and solving the problems of low bismuth sulfur recovery rate and resource waste in the original process.
- 1
-
Experimental Research on the Precipitation Extraction of Ionic Rare Earths from Mine Using Active Magnesium Oxide
Abstract:
The ammonium salt precipitation process for rare earth extraction from ion-type rare earth ores can cause a series of ecological problems, including eutrophication of receiving waters, disruption of aquatic ecological balance, acidification and hardening of surrounding soils, and threats to human health. Aiming at such ammonia-nitrogen pollution issues, taking the leachate of a certain ionic rare earth ore in Longnan as the research object, a light-burned, ammonia-free and highly active magnesium oxide precipitant was developed and prepared, and its influence on the precipitation behavior of rare earths was studied. Meanwhile, the precipitation products industrial magnesium oxide. When the active magnesium oxide is used as the precipitant, under the optimal under different magnesium oxide systems were systematically compared by XRD, SEM and TG-DTG characterization. The results show that the reactivity of the prepared magnesium oxide is much higher than that of precipitation conditions (the dosage ratio is 8, the reaction temperature is 90 ℃, and the reaction time is 4 hours), the precipitation product with a purity of 37.45% and a precipitation rate of 96.17% can be obtained. However, when industrial magnesium oxide is used as the precipitant, the obtained precipitation product has a lower purity of 32.07% and a precipitation rate of 90.17%. In the system of active magnesium oxide, obvious diffraction peaks of Y?O?, Dy?O?, etc. appear in the rare earth mixed oxide, and the crystallization development of the product is better than that in the system of industrial magnesium oxide. The surface is dense and smooth, with a clear outline and uniform particles. The research results provide new theoretical and technical support for the green chemical extraction of ionic rare earth ores.
- 1
-
Study on the Response Characteristics and Failure Mechanisms of Hydraulic Fracturing in Gently Inclined Hard Roofs
Abstract:
To investigate the fracture distribution patterns of rock strata under hydraulic fracturing in gently inclined hard roof conditions and determine the critical initiation stress range for hydraulic fracturing, this study takes the I010206 working face of Kuangou Coal Mine as the engineering background. By combining the mechanical properties of roof strata materials, rock-like material specimens were prepared. Using a true triaxial hydraulic fracturing experimental setup, physical simulation experiments under different stresses and initiation pressures were conducted. The fracture distribution laws and spatiotemporal characteristics of fracture development under varying stresses and initiation pressures were obtained. Comprehensive analysis through numerical simulation software revealed the three-dimensional spatial distribution characteristics of fractures under different stress and initiation pressure conditions. Field application of experimental results demonstrated that: ① The horizontal stress difference significantly influences fracture propagation morphology. Under low stress differences, fractures exhibit unilateral dominant propagation with larger areas, while high stress differences promote symmetrical double-wing patterns with increased propagation resistance. ② Acoustic emission event counts, amplitudes (83.2-121.1 dB peak values), and spatial distributions (3698-4702 events) show high correlation with fracture initiation and propagation processes, effectively characterizing critical damage states. Comparative analysis of three numerical models indicates that excessive horizontal stress differences increase propagation resistance and constrain fracture extension, ultimately reducing total fracture area. ③ The critical initiation pressure range for hard roof hydraulic fracturing in Kuangou Coal Mine was determined as 10.80-16.79 MPa, with a recommended minimum operational pressure of 16.79 MPa. Engineering validations confirmed the effectiveness of directional staged fracturing technology in significantly reducing unsupported roof area and impact risks. This research provides theoretical foundations for deep mine roof fracturing design and disaster prevention.
- 1
-
Study on the Ground Stress Law under Fault-Bearing Conditions Based on the Stress Relief Method and Rapid Stress Boundary Method
Abstract:
It is very important to master the distribution law of ground stress in metal mine working face for mine safety production. Aiming at the complex problem of ground stress distribution in working face under the condition of fault structure in a spodumene ore body, combined with numerical simulation and field measurement, the distribution law of ground stress is explored. Based on the measured data, the initial state of underground engineering under the action of real in-situ stress field is simulated by using the fast stress boundary method, which shows that the in-situ stress concentration occurs in the upper and lower parts of the hanging wall of each fault, while the stress distribution at other positions has a good hierarchy. The numerical simulation inversion data show that the ground stress contour of the working face on both sides of the fault changes abruptly, especially when the fault density is large, the ground stress increases from 7 MPa to 20 MPa. In the absence of faults, the actual measured in-situ stress results are in good agreement with the stress values of the numerical simulation analysis results, which indicates that the fast stress boundary method can accurately reflect the in-situ stress state in engineering practice, and can make up for the deficiency that the measured points of in-situ stress basically avoid the bad structural planes such as faults.
- 1
-
The Impact of Self-Sacrificial Leadership on Miners' Unsafe Behaviors: A Dual-Pathway Chain Mediation Model
Abstract:
Safety production constitutes the cornerstone of intelligent mining transformation, aiming to enhance enterprise safety management efficiency and effectively reduce the incidence of production safety accidents. Grounded in the work-family resources model, this study constructs a dual-chain mediation model incorporating leader identification, role overload, work-family facilitation, and work-family conflict as mediating variables. The empirical analysis was conducted using 502 valid questionnaires collected through structured surveys. Hypothesis testing reveals three key findings: First, self-sacrificial leadership exhibits a significant direct negative effect on miners’ unsafe behaviors. Second, self-sacrificial leadership indirectly reduces unsafe behaviors through the sequential mediation of leadership identification and work-family enrichment. Conversely, it indirectly increases unsafe behaviors via the chain mediation of role overload and work-family conflict. Mining enterprise managers should prioritize employees' work-family balance by adaptively adjusting management strategies and leadership styles to mitigate occupational hazards.
- 1
-
Effect of naphthohydroxamic acid on flotation of ilmenite and titanaugite
Abstract:
Ilmenite and titanaugite have similar properties, making their flotation separation quite challenging. The adsorption modes and action mechanisms of naphthohydroxamic acid on the surfaces of ilmenite and titanaugite were investigated , and the key factors affecting the flotation performance were clarified through flotation tests, Zeta potential measurements, and adsorption capacity tests. The results show that the collecting effect of naphthohydroxamic acid on ilmenite is stronger than that of titanaugite. The action mechanism of naphthohydroxamic acid on ilmenite and titanaugite was discussed through Zeta potential test and adsorption capacity test. The results show that the adsorption capacity of naphthohydroxamic acid on the surface of ilmenite was significantly higher than that of titanaugite, and the effect on the surface potential of ilmenite was greater than that on the surface potential of ilmenite. Such adsorption difference increases the difference in floatability between ilmenite and ilmenite. The actual ore test results show that titanium concentrate with TiO2 grade of 47.26% and recovery rate of 80.60% can be obtained by using naphthalamic acid as collector of ilmenite in flotation closed-circuit test, and the flotation separation of ilmenite and titanaugite can be realized. This study provides theoretical support for the development of new flotation reagents for ilmenite and the optimization of the titanium ore flotation process.
- 1
-
Engineering Optimization of Cut Blasting Methods in Roadway with Layered Surrounding Rock
Abstract:
As a critical step in tunnel excavation, cutting blasting directly affects rock fragmentation sizeand construction efficiency. However, in rock masses with well-developed jointed and layeredstructures, the orientation and properties of joints can significantly alter the damage modeunder explosive loading, often leading to insufficient fracturing and reduced blastingeffectiveness. To investigate the influence mechanism of structural planes on cutting blastingresponse, this study takes a mine tunnel as the engineering background and establishes a quasi3D finite element model incorporating joint inclination. The ALE fluid-structure coupling algorithm is adopted to comparatively analyze the stress wavepropagation and damage evolution characteristics under joint-free and jointed conditions.Results show that jointed structures significantly weaken the coupling intensity of stress waves,resulting in the failure of effective fracturing in the central cutting zone. To address this issue, anoptimized design scheme with additional auxiliary cutting holes is proposed and validatedthrough both numerical simulations and field tests. The results demonstrate that the improvedscheme enhances energy concentration in the cutting area, promotes penetration and rockfragmentation, and reduces the proportion of oversized blocks. This research providestheoretical support and practical quidance for cutting blasting design and rock mass responsecontrol under complex structural conditions.
- 1
-
Experimental study on fly ash-based foam concrete and its application in mine filling industry
Abstract:
The ore rock in some areas of Shanggong Gold Mine of Kunyu Company is broken, and it is planned to adopt the upward drift mining method. However, the mine has not yet built a filling system. In order to solve the contradiction between mining and filling and ensure the smooth development of the mining industry test, it is decided to use lightweight foam concrete to fill the empty area. Firstly, the slump test was carried out to explore the basic data of foam concrete slurry reaching the paste state under different cement dosage conditions. The strength ratio test of different cement addition amount and different fly ash addition amount was further carried out to obtain the basic parameters of the strength of the filling body, and the filling ratio was recommended and the filling cost was analyzed in combination with the mining method. X-ray diffraction ( XRD ) and scanning electron microscopy ( SEM ) were further used to study and analyze the cementitious mechanism of fly ash-based foam concrete. Finally, the actual filling effect of fly ash based foam concrete was verified by industrial test. The results show that the cost of fly ash-based foam concrete material is 103.8 yuan / m3, which is 46 % lower than that of traditional cement foam concrete. The cost of industrial test filling ton ore is 42 yuan / t, which is consistent with the experimental results. The filling technology of fly ash-based foam concrete has the advantages of low investment, short construction period and reasonable filling cost, which can be popularized and applied in small-scale precious metal mines.
- 1
-
Research on Application of Cement-Fly Ash-Carbonated Steel Slag Ternary Binder in Cemented Paste Backfill
Abstract:
In response to the current reliance of traditional cemented tailings backfill technology on high-carbon-emission and high-cost cement as a binder, a novel cement-fly ash-carbonated steel slag (CFCS) ternary binder system (with a mix ratio of 40% cement, 30% carbonated steel slag, and 30% fly ash) was proposed. By synergistically utilizing industrial solid wastes (fly ash and steel slag), a backfill binder material with both low-carbon and economic advantages was developed. The results indicate that due to the faster reaction rate of cement, the early compressive strength of backfill specimens using cement as the binder is slightly higher than that of the CFCS system. However, after 28 days of curing, the compressive strength of the CFCS system matches that of cement-based backfill specimens, with the strength improvement attributed to the continuous hydration of fly ash generating cementitious gels. The fluidity of the CFCS backfill slurry is superior to that of the cement system, as the "ball-bearing effect" of fly ash and the optimized microstructure of the CFCS system significantly reduce particle friction resistance. Compared to alkali-activated binders, the CFCS system achieves comparable mechanical performance while avoiding the high cost and potential environmental risks associated with strong alkaline activators. The carbonated steel slag is treated using a wet carbonation process, where CO? reacts with active minerals in the steel slag to achieve carbon sequestration and performance enhancement. In terms of economic and environmental benefits, the CFCS system reduces production costs by 22% and carbon emissions by 63.6% compared to cement. This system addresses the challenges of solid waste accumulation, backfill costs, and carbon emissions through the resource utilization of steel slag, providing an innovative technological pathway for achieving carbon neutrality in the mining industry.
- 1
-
A Study on the Slope Stability of an Ionic-Type Rare Earth Mine in Jiangxi Province
Abstract:
Due to prolonged mining activities and complex natural environmental conditions, slope stability issues have become increasingly prominent in a rare earth mining area in Longnan County, Jiangxi Province. To identify the key influencing factors, this study systematically evaluated the geological conditions and slope stability characteristics of the study area through field investigations and data analysis. Physical and mechanical parameters of the rock and soil mass were obtained through drilling and laboratory tests. Based on these parameters, a cross-sectional model of slope 1-1’ was established using the LIZHENG Geotechnical software. The slope stability under natural and heavy rainfall conditions was analyzed using both circular slip and polyline slip methods. The calculation results show that the safety factor under natural conditions is 1.59, indicating a stable state, while under heavy rainfall conditions, the safety factor drops to 0.913, indicating instability. Rainfall significantly reduces the shear strength of the soil and increases pore water pressure, which is a key factor leading to slope failure. The research results provide a scientific basis for the design of slope protection measures in the mining area and offer a reference for geological disaster prevention in similar rare earth mining regions.
- 1
-
Analysis of Runoff Infiltration Pattern in Surface Collapse Zone of Open Pit to Underground Mining Based on HEC-RAS
Abstract:
Currently, numerous mines in China are transitioning from open-pit mining to underground mining operations. During the transition from open-pit to underground caving mining, the deformation and fracturing of overlying surrounding rocks significantly increase permeability, creating pathways for heavy rainfall infiltration and triggering hazards such as underground water inrushes. To accurately assess the runoff infiltration volume in subsidence areas under heavy rainfall conditions, a calculation method based on precise delineation of surface catchment infiltration zones was proposed. Using the Shilu Iron Mine of Hainan Mining as a case study, infiltration zones—including the caved zone, water-conducting fracture zone, and runoff area—were classified under different mining states by integrating surface subsidence deformation data and numerical simulations of mine catchment hydrology. The rainfall infiltration volumes under storm conditions were calculated separately for each zone. Results indicate that the runoff infiltration volume in the North No.1 Stope subsidence area increased from 182,874 m3/d under current conditions to 218,118 m3/d post-mining completion, representing an increment of 35,244 m3/d. Three-tiered anti-seepage zones were further established, with advises of tailored measures proposed for each region. Level 1 zones (submerged caved zones and water-conducting fractures) require comprehensive measures including layered crack filling, impermeable membrane installation, and pump drainage systems. This study provides a scientific basis for designing mine drainage systems and preventing water inrush disasters.
- 1
-
Study on the development characteristics and prediction of ground fissures in high-intensity mining in western mining area
Abstract:
Ground fissures will accelerate land degradation and soil erosion, induce secondary geological disasters such as landslides and collapses, and restrict regional sustainable development. To further reveal the development characteristics of ground fissures in high-intensity mining, taking the 615 working face of a mine as the engineering background, the relevant research was carried out by means of field measurement, experimental simulation, theoretical analysis and engineering application. The results show that according to the different deformation properties, the distribution types of ground fissures are mainly tensile, step and collapse types. The propagation period of the in-plane fissures is shortened and the closure degree is reduced during the working face advancing process. The development degree of ground fissures is stronger than that of general geological mining conditions. The number of fissures with widths of 0 ~ 100 mm, 10 ~ 500 mm and greater than 500 mm accounts for 38 %, 56 % and 6 % respectively. The fractures of the overlying strata develop synchronously with the fracture of thick-hard rock strata and finally penetrate to the surface, showing the distribution characteristics along the horizontal direction with the development degree as the boundary. Based on the critical deformation value of ground fissures, the strike, downhill and uphill fissure angles are predicted to be 79.8 °, 74.1 ° and 79.5 °, respectively, and the maximum relative error is 7.1 %. The formula for calculating the critical value of the depth-thickness ratio of the penetrating fissure is given. The research results have important reference significance for land restoration and prevention in mining areas.
- 1
-
Sensitivity analysis of slope stability with steeply dipping weak layer based on grey correlation-orthogonal test method
Abstract:
Slopes with steeply dipping weak interlayers are often unstable due to the development of sliding surfaces along the weak interlayers. Aiming at the sensitivity analysis of the factors affecting the stability of open-pit slopes with steeply dipping weak interlayers, a grey correlation-orthogonal test composite algorithm is proposed. Combined with orthogonal test design, range analysis and grey correlation method, a case study of an open-pit mine slope in Yunnan was carried out. The safety factor of the slope is calculated by the strength reduction method, and the four-level five-factor orthogonal test L16 ( 45 ) is designed to analyze the influence of the thickness, inclination angle, distance from the slope surface, internal friction angle and cohesion of the weak interlayer on the stability of the open-pit slope. The results show that the dip angle of weak interlayer has the most significant influence on slope stability, and its range accounts for 50.94 %, followed by the internal friction angle of weak interlayer, which accounts for 21.89 %, and the influence of other factors is weak. The composite algorithm is consistent with the traditional range analysis results, but the sensitivity ranking is clearer, which verifies the reliability of the method. It is suggested that the slope angle should be controlled less than the dip angle of the weak interlayer in the slope design, and the slope stability should be enhanced by increasing the internal friction angle of the weak interlayer. By quantifying the sensitivity weight of key factors, it provides theoretical support for disaster warning, support design and emergency response.
- 1
-
Research on Microseismic Signal Denoisig Based on ICEEMDAN and Improved Wavelet Threshold
Abstract:
In mining environments with complex background noise, making it difficult for existing denoising methods to effectively extract microseismic signals generated by rock mass deformation and fracturing. To tackle this problem, a hybrid denoising method combining Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) and an Improved Wavelet Threshold (IWT) algorithm is proposed. The proposed method first decomposes the noisy microseismic signal into Intrinsic Mode Functions (IMFs) via ICEEMDAN; then selectively processes noise-dominant IMFs based on correlation coefficient analysis using the improved wavelet threshold; and ultimately reconstructs the denoised microseismic signal through wavelet synthesis. Test results demonstrate the superiority of the ICEEMDAN-IWT method over existing algorithms in critical metrics: Signal-to-Noise Ratio (SNR):28.06 dB (maximum); Normalized Correlation Cofficient (NCC): 0.9992; Mean Square Error (MSE):0.01445. Application to field data confirms effective suppression of high-frequency noise while preserving critical microseismic features, providing a robust technical framework for advanced signal processing in rock stability monitoring. However, the denoising performance for waveform data with high amplitude ratios remains limited, and subsequent research might incorporate deep learning approaches for performance enhancement.
- 1
-
Research on surrounding rock support of mining roadway based on yellow mud roof classificationGUO Pengfei1, ZHAO Yiqing2,3, LIU Yang2,3, AO Rongxing2,3
Abstract:
Aiming at the problem of difficult management of yellow mud roof and poor support effect in roadways that severely restricts safe mining in a Shanxi coal mine, this study takes a typical working face as the engineering background to conduct in-depth research on support schemes and their effectiveness for yellow mud roof mining roadways through field investigation, laboratory tests, theoretical analysis, and numerical simulation. First, the yellow mud roof was classified based on engineering geological conditions. Subsequently, physical and mechanical parameters of different roof strata were accurately determined through physical-mechanical experiments, providing a reduction basis for numerical simulation parameters of support schemes. Corresponding roadway support schemes were formulated and their effectiveness was evaluated using numerical simulation technology. The research results demonstrate that:The roof of yellow mud can be divided into five categories. The main components of yellow mud are clay minerals and quartz. The internal friction angle of yellow mud is 30.78 °, and the cohesion is 75.362 kPa. Class I, III and IV roof roadways are supported by anchor net cable, class II roof is supported by anchor net, and class V roof is supported by I-steel shed. The results of numerical simulation and field measurement show that the designed support scheme can effectively control the deformation of roadway surrounding rock and ensure the stability of yellow mud roof roadway. The research results can provide important guidance for roadway support design under similar geological conditions.
- 1
-
Comparative Study on Strength Prediction Models of Grouting Materials under Small-Sample Data Conditions
Abstract:
The strength prediction of grouting materials holds significant scientific importance for enhancing the reliability of material design in mining engineering.To address the limitations of traditional empirical models in accurately capturing the relationship between material composition and mechanical strength, as well as the insufficient generalization capability caused by small-sample datasets, this study proposes a machine learning framework integrating physical mechanisms and data augmentation techniques. Four machine learning methods were systematically evaluated for compressive strength prediction: Random Forest Regression (RFR), Artificial Neural Network (ANN), Support Vector Regression (SVR), and Linear Regression (LR). Experimental results demonstrate that the proposed framework improves the mean coefficient of determination (R2) by 17.1% across all models. The optimal model, RFR, achieves a mean absolute error (MAE) of 2.59 MPa, representing reductions of 11.5%, 20.6%, and 32.4% compared to LR, SVR, and ANN, respectively. Feature importance analysis reveals that graphite content contributes 37.6% to compressive strength variability. This study confirms that physics-informed data augmentation enhances the robustness of small-sample modeling, while the interpretable feature importance quantification from RFR provides actionable insights for optimizing engineering material mix proportions.
- 1
-
Optimization of Discharge Strategy of Open-pit Mine Based on DPRS-NSGA-III
Abstract:
Open-pit mine production is affected by geological fluctuations, and it is difficult for traditional methods to coordinate multi-target ore production strategies. In view of the uncertainty changes of ore grade and unit mining cost in the process of ore extraction, a multi-objective uncertainty optimization model with the goal of minimizing unit cost, maximizing total ore output and minimizing the standard deviation of grade fluctuation was established, and the Monte Carlo method was used to simulate the random changes of geological parameters. In order to improve the stability and diversity of the solution set, a dynamic reference point perturbation jumping mechanism and a target scale adaptive scaling strategy were designed and embedded in NSGA-III. Taking a large molybdenum mine as the research object, the results show that the total ore yield of the optimized scheme was increased by 2.03%, the unit mining cost was reduced by 2.17%, and the grade deviation was controlled within 0.005 percentage points. The obtained Pareto solution set is evenly distributed in the three-dimensional target space, and there is no abnormal aggregation or collapse. The proposed multi-objective optimization method has good adaptability and practical application value in coping with the uncertainties in the open-pit mine mining strategy.
- 1
-
Research on Multi-body Coupled Dynamics Analysis and Safety Design of an Inclined Shaft Hoisting Container
Abstract:
Conventional runaway protection for standard inclined shaft hoisting conveyances relies primarily on passive safety devices deployed along the shaft walls for interception, aiming to prevent catastrophic accidents caused by accelerated collisions. To address this limitation, a novel conveyance structure incorporating integrated mechanical braking, maintenance interlock, and spring buffering mechanisms is proposed. Based on this structural design, a multi-body coupled impact dynamics model for the conveyance–inclined track system is established. Integrating theoretical derivation, experimental validation, and virtual prototype simulation, this study elucidates the formation mechanism of the rear-wheel lift angle during emergency braking events and investigates the quantitative effects of buffer spring stiffness, track inclination angle, impact velocity, and payload on the dynamic response characteristics of the conveyance. The results demonstrate that:An optimal buffer spring stiffness range (10 000–15 000 N/mm) exists, reducing impact force by 13.4% and lifting angle by 17.4%.Inclined track angle and impact velocity are positively correlated with the rear wheel lifting angle. Under rated load conditions, the lifting angle is 15%-30% lower than under no-load conditions, indicating that the gravitational moment of the load suppresses derailment risk.As the inclined track angle increases from 10°to 30°, the derailment velocity decreases from 9.5 m/s to 7.3 m/s for rated load, and from 9.0 m/s to 5.2 m/s for no-load conditions. The safety margin improvement due to loading reaches up to 28.8%. These findings provide a theoretical basis for the anti-impact design and safe braking strategies of hoisting containers.
- 1
-
Study on the Relationship Between Physical Properties of Tailings and Solid Flux
Abstract:
To investigate the influence of tailings' physical properties on solid flux and optimize thickening process parameters, this study systematically analyzed full tailings samples from 10 typical metal mines to establish quantitative relationships between particle size, density, and solid flux. The particle size distribution was determined using a Malvern laser particle size analyzer, and static flocculation-sedimentation tests combined with dynamic thickening experiments were conducted to develop a predictive model based on a particle size-density composite parameter. The results demonstrate that: (1) Under static flocculation conditions, flocculant type and dosage significantly affected sedimentation rate and underflow concentration, with optimal flocculation improving sedimentation efficiency by 20%-30%; (2) Solid flux showed a strong positive correlation with the square root of median particle size and density-modified parameter (γ-1) (R2≥0.94), and the nonlinear regression-based composite parameter model achieved prediction errors below 5%; (3) In dynamic thickening, feed rate exhibited a linear positive correlation with solid flux, while overflow water solids content imposed dual constraints on flux thresholds. Comparative tests revealed that dynamic thickening increased underflow concentration by 10%-15% compared to static sedimentation, fully validating the technical superiority of deep-cone thickeners in high-density slurry preparation. This research provides theoretical foundations and technical support for efficient tailings thickening and intelligent backfill systems in mining operations.
- 1
-
Experimental Study on the Four-track All-wheel Drive Traveling Mechanism and Working Performance of the Deep-sea Mining Vehicle
Abstract:
Aiming at the stable driving problem of complex terrain of deep-sea cobalt-rich crusts, a four-track all-wheel drive independent active lifting driving mechanism scheme and an adaptive terrain control method were proposed, and a four-track driving mechanics model was established. Based on Recurdyn, a multi-body dynamics simulation model was constructed to analyze the force characteristics of the four-track driving mechanism in straight driving, climbing, obstacle crossing and turning. Laboratory tests and sea trials were carried out to verify the driving mechanism. The test results show that the test results are close to the theoretical calculation, and the driving performance error of the driving mechanism is within 10%. The driving effect of the driving mechanism was effectively improved through the adaptive method. Compared with the driving on the undulating terrain, when the speed is 0.05m/s, the adaptive control of straightness reduces the deviation value by more than 40%, and the use of body leveling control can improve the driving stability by 2 to 3 times. However, in general, with the increase of driving speed, the adaptive control effect is constantly weakened. When the speed is 0.2m/s, the control effect is deviated. The research results can provide reference for the development of deep-sea complex terrain driving technology and equipment.
- 1
-
Research on the Protection Scheme of Caving Hazards of Open-Stope Method in Small and Medium Sized Iron Mine
Abstract:
The open-stope method is mostly used in small and medium-sized iron mine with medium stability of ore and rock. In practical application, it is easy to induce large-scale caving of roof and surrounding rock in goaf, which seriously threatens the safety production of mines. The complex and irregular goaf group left over by the open-stope method in Zhuba Iron Mine in Nanjiang city is taken as the research object. Under the premise of analyzing the attributes of the goaf, a more detailed three-dimensional numerical model of the ore and rock is established by the surface point cloud data obtained by the high-precision aerial photography of the unmanned aerial vehicle and the mine production plan. The dynamic evolution laws of the mechanical properties of the surrounding rock in the goaf group are studied, and the following conclusions are obtained: (1) The height, volume, area, and quantity of the goaf in the 1318 m middle section are all the maximum values, which are the key factors restricting the safe mining of the lower ore body. (2) The residual ore body in the 1318 m middle section and the residual horizontal pillar directly facing the goafs in the 1258 m middle section are not suitable for mining. To ensure the safe mining of the lower ore body, a systematic protection scheme for the collapse hazard and impact air wave hazard of the goaf group is proposed. The results show that the 1258 m middle section is continuously mined about 13 months, and the recovered ore volume is about 18.89 tons. During this period, the large-scale caving in the 1318 m middle section goaf is unhappen. During the normal mining period of the middle ore body in the 1208 m middle section, the different degrees of caving activities occur in the goafs of the middle sections of 1318 m and 1258 m. However, the caving hazards do not affect the production area, verifying the safety and practicality of the caving hazard protection plan.
- 1
-
Evaluation and dynamic prevention and control of water inrush on deep roadway roof based on PCA-entropy modelGeng Ming[1], WANG Huan2, XU Qingyun3
Abstract:
To accurately assess the risk of water inrush from the roof of deep underground roadways and address the low credibility of traditional evaluation methods due to redundant indicators and subjective weighting，a comprehensive calculation method combining principal component analysis (PCA) and the entropy method is proposed. PCA is used to reduce the dimensionality of multi-source indicators and eliminate information overlap， quantify the weights of each principal component，and the entropy method is introduced to objectify the comprehensive evaluation index. Based on the sample input data set of various indicators，a water inrush evaluation model for coal seam roof is constructed with the logical framework of “principal component extraction - comprehensive index calculation - model comparison and verification - dynamic prevention and control”. The results show that the water-conducting coefficient of faults mainly affects the water inrush from the roof of the working face，followed by the permeability coefficient. The high fitting rate of the comprehensive index calculated based on the PCA-entropy method and the actual water seepage indicates that five water-rich danger levels are classified. It is determined that the area 518-678m away from the cutting eye of the 1315 working face is in the extremely high-risk zone，and the area 0-425m is in the high-risk zone. According to the sources of water inrush from the roof in different areas，a technical path of “zonal prevention and control - three-dimensional interception - drainage optimization”is proposed. The research results improve the classification and division of water inrush danger levels and provide a new method for the safe mining of deep resources.
- 1
-
Research on Inter-Hole Delay Time for Vibration Reduction by Phase Staggering in Underground Medium and Deep Hole
Abstract:
The safety threat posed by blasting vibration to surrounding structures urgently requires effective solutions. Traditional vibration reduction methods heavily rely on empirical parameters and often lack robust statistical support, particularly with small sample sizes. In this study, blasting vibration was monitored, and Fast Fourier Transform (FFT) was employed to extract peak frequencies. Subsequently, the Bootstrap method, Bayesian analysis, and Maximum Likelihood Estimation (MLE) were utilized for a comparative analysis of the frequency’s statistical characteristics. The results indicated that, under small sample conditions, the Bootstrap method (which requires no distributional assumptions) and the Bayesian method (based on iterative prior knowledge) reduced prediction errors by 20%-30% and exhibited significantly enhanced stability compared to MLE. Field experiments, conducted after optimizing the inter-hole delay time to 8 ms, demonstrated that Peak Particle Velocities (PPVs) in the X, Y, and Z directions decreased by over 32%, while the resultant PPV was reduced by 40.2%. This research provides a data-driven basis for parameter optimization in underground medium-to-deep hole blasting, improving vibration reduction efficiency by more than 50% compared to empirical approaches.
- 1
-
Precise Recognition of Mining Land Features Based on the Dual-Branch DB-TransUnet Model
Abstract:
In remote sensing imagery of mining areas, the presence of complex vegetation cover and ambiguous object boundaries poses significant challenges to the accuracy of traditional segmentation models. To address these issues, this paper proposes a dual-branch DB-TransUnet model. The model innovatively constructs a dual-branch encoder architecture and integrates features from both branches using an Adaptive Weighted Fusion (AWF) module. Additionally, a Channel Attention (CA) module is employed to optimize the feature weighting during the decoding process, enabling better focus on key regions while effectively suppressing background noise. Experimental results demonstrate that the AWF and CA modules lead to improvements of 3.61% and 39.78% in mIoU, respectively. The proposed model outperforms mainstream methods such as U-Net and SegFormer, particularly in scenarios with severe vegetation interference. The study validates the effectiveness of multi-source feature complementation and weight fusion strategies in mitigating vegetation-related disturbances in complex mining environments, providing a reliable solution for high-precision intelligent monitoring of open-pit mines.
- 1
-
Research on Multi-step Prediction of Roadway Deformation Based on AE-TCN-Transformer Parallel Model
Abstract:
To achieve accurate prediction of roadway deformation, a parallel prediction model of TCN-Transformer optimized by the Alpha Evolution Algorithm (AE) is proposed. This model fuses the Temporal Convolutional Network (TCN) and the Transformer model through a parallel architecture, giving full play to the advantages of the two in feature extraction at different scales: TCN uses dilated causal convolution to mine local temporal features, and Transformer captures long-term change trends through the multi-head self-attention mechanism. Finally, the multi-model dynamic feature fusion mechanism guided by temporal attention is used to output the results. At the same time, the AE algorithm is introduced to optimize the parameters. With the adaptive evolutionary path and the dual-step mechanism, the robustness of the model in complex time-series data is enhanced. Taking the roadway displacement monitoring data of three monitoring points in different sublevels of an iron mine in Yunnan as the research object, the experimental results show that for the AE-TCN-Transformer model within the prediction range of 6 to 48 steps, the root mean square error is controlled below 0.0132 mm, the symmetric mean absolute percentage error is lower than 0.09%, and the coefficient of determination is higher than 0.97, which is significantly better than single models. It fully verifies the accuracy and reliability of this model in roadway deformation prediction and provides a new path for accurate prediction of roadway deformation.
- 1
-
Fig. 1 Method flow chart of NRBO-BPNN
Abstract:
Rockburst intensity prediction is a critical task in mine safety management. To improve the accuracy and practical application of rockburst prediction, this paper proposes a rockburst intensity prediction model (NRBO-BPNN) that integrates the NRBO optimization algorithm with a Back Propagation Neural Network (BPNN). The NRBO optimization algorithm addresses the issue of local optima encountered in the traditional BPNN training process, enhancing the network"s convergence speed and global search ability. Compared with traditional BPNN, Support Vector Machine (SVM), Random Forest (RF), and Extreme Learning Machine (ELM) models, the NRBO-BPNN model exhibits higher accuracy and stronger generalization ability in predicting rockburst intensity. Furthermore, by developing a comprehensive rockburst intensity prediction system, this model is applied to the Maluping Mine and Dongguanshan Copper Mine, validating its effectiveness in real-world engineering. The results show that the NRBO-BPNN model can provide reliable predictive support for mine safety design and holds significant practical application value.
- 1
-
Study on the effect of different erosive environments on the durability of modified grouting materials
Abstract:
Grouting materials are widely used in various complex environments such as filling of karst areas, which put forward more stringent requirements on the ability of grouting materials to resist chloride-sulfate compound erosion, carbonate erosion, and water-soluble erosion. In this study, modified grouting materials were prepared by using rice husk ash and slag as partial substitutes for cement, and the effects of different erosive environments on the durability of modified grouting materials in karst areas were evaluated by compressive strength, strength erosion coefficient and mass loss rate. The results show that the modified rice husk ash-slag-cement grouting material has improved resistance to chloride-sulfate erosion, carbonate erosion and water-soluble erosion, with strength erosion coefficients of 0.855, 0.852 and 0.945, respectively, which is more resistant to various erosive environments than the pure cement grouting material, and the quality loss after erosion is only 3.30%, 2.38% and 1.95%. And through the micro-morphological observation to analyze the mechanism of durability improvement of the modified grouting material, it was found that the rice husk ash and slag through the hydration reaction to generate a more dense hydration products, dense structure can inhibit the destruction of the original hydration products of the various erosive environments, and the amorphous SiO2 in the rice husk ash can be with the Ca(OH)2 volcanic ash reaction, or the slag secondary hydration to generate more C-S-S-H gel, thus making the modified grouting material resistant to chloride salt, sulfate, carbonate and water.
- 1
-
Research on Stability Analysis of Makeng Iron Mine Mining Site Based on Mathews Diagram Method and FLAC3D
Abstract:
This study investigates the rock mass stability of the 61-65 line mining area of the Makeng Iron Mine by combining the Mathews stability diagram method and FLAC3D numerical simulation techniques. A stress-displacement model was developed to analyze the effects of mining structure parameters (span, length, and height) on stability. The results show that after the orebody is excavated, the roof and sidewall exhibit significant tensile and compressive stress concentration, respectively. The span of the mining area has a notable impact on the stress concentration in the roof, while the length primarily controls the stress release and displacement of the sidewall. Numerical simulation results indicate that the mining parameter (20×15×54m) performs best in terms of sidewall displacement and roof stress concentration. Reducing the length of the mining area effectively reduces sidewall displacement and stress concentration, enhancing the stability of the rock mass. Although reducing the mining height to 36m helps suppress horizontal displacement to some extent, the roof still faces a higher risk of collapse in fractured rock zones, indicating that adjusting the mining height alone cannot resolve local stability issues. A mining plan based on rock mass quality differences effectively optimized the mining parameters for fractured zones, and by shortening the mining area length, it successfully alleviated the sidewall overbreak problem in the 63-1R mining area. The results provide theoretical support and engineering guidance for optimizing mining structure parameters and improving rock mass stability at Makeng Iron Mine, with strong practical value.
- 1
-
Study on Structural Parameters and Support Optimization of a Gold Mine Stope Based on Mathews Graphic Method
Abstract:
A gold mine has developed joints and broken ore bodies in the local middle section of a gold mine. Combined with the stability of ore and rock, two schemes of upward drift filling mining method and small sublevel filling mining method are proposed. By comprehensively comparing the technical and economic indicators, advantages and disadvantages of each method, the upward drift filling mining method is finally selected and the first and second step approach sizes are designed by Mathews graphic method. The high × wide × long is 3.3 × 7.0 ~ 8.0 × 40 m. According to the pre-support mechanism of the anchor cable, the support scheme is designed. The crack development state of the broken area is simulated by the discrete element software, and the crack depth of the surrounding rock is quantitatively characterized by the crack area index, and the stability of the stope is analyzed. The results show that after the anchor cable support, there is no obvious falling block in the roof of the two-step approach and no large crack connection through area and surrounding rock cracking area distribution ; combined with the support effect and economic demand, the best support scheme is when the anchor cable mesh is 3.3m × 4.0m. The roof displacement is about 84mm, which is reduced by 26.96 %, the total number of cracks is reduced by 37.33 %, and the equivalent depth of the cracking zone is 0.64m, which is reduced by 36.63 %. Through the field industrial test, the peak value of the roof subsidence of the approach is successfully controlled at 91 mm, and about 755.5 million yuan of economic benefits are brought to the mine.
- 1
-
Experimental study on comprehensive utilization of an iron mine in Hami
Abstract:
Resources of Lean iron ore are abundant in Hami area of Xinjiang. The grade of an iron ore is 14-20%,associated with Ti, V and P, which belongs to ultra-low vanadium-titanium magnetite. In order to explore the possibility of its comprehensive utilization, phase analysis, microscopic identification and other ore process mineralogy research work were carried out to find out the occurrence state, embedding mode and particle size of useful minerals such as magnetite, ilmenite and apatite. The dry preconcentration process and the comprehensive recovery of iron ( vanadium ), titanium and phosphorus were studied. Finally, the whole process principle test process was determined : dry preconcentration-flotation desulfurization-flotation recovery of phosphorus-low intensity magnetic separation of iron-gravity separation of titanium, iron concentrate TFe57.15 %, recovery rate 34.31 %, titanium concentrate TiO2 46.40 %, recovery rate 20.08 %, the grade of phosphate concentrate is 28.25 %, and the recovery rate is 53.81 %. The distribution of rare earth elements in various concentrate products obtained from the test was determined. It was found that rare earth had the highest correlation with apatite, and the recovery rate of rare earth in phosphate concentrate was 60 %, which could provide reference for the comprehensive utilization of such vanadium-titanium magnetite in Xinjiang.
- 1
-
Research on the Path of Exploring the Green Development Standard System Construction of China"s Mining Industry
Abstract:
Continuously promoting the green, low-carbon and high-quality development of mining is an important measure and handle for the construction of civilization in the new era of our country. The National Mineral Resources Planning clearly proposes to actively explore and establish a new path of green and low-carbon development of mining industry with goals such as "green mining pattern". The new round of strategic action of mineral resources exploration has also put forward new requirements for the green development of mining industry. In the field comprehensive utilization of mineral resources, the exploration research on the path of green and low-carbon high-quality development of mining industry in China is guided by the top-level design idea standard system and the standardization technology means are applied to explore the path of green and low-carbon high-quality development of mining industry in China. It is of great guiding to support and promote the green and low-carbon high-quality development of mining industry. Standardization is an activity to formulate commonly used and reusable clauses for solving existing problems or potential in a certain range. Focusing on the standardization field of green mining, with the support of existing research results of mineral resources, the top-level design of green development concept the technical logic of mineral resources standard research are carried out. The research work in the field of green mining basic general standardization, green geological survey standardization, green mine standard and mineral resource conservation and intensive use standardization is carried out. With the theory and model of the construction of natural resource standard system, the research on the standard system of green is carried out from three levels: basic general, category general and sub-category general. In this way, the structure and content of the standard system for the green development of mining analyzed, and the key directions and implementation paths for the standardization research of green and high-quality development of mining industry in China are proposed, and the high-quality promotion of development of mining industry in China is carried out.
- 1
-
Research on the Collision Characteristics of Grinding Spheres in a Vertical Stirred Mill Based on DEM-CFD
Abstract:
In order to explore the collision characteristics of grinding spheres during the complex operation process inside the cylinder of vertical stirred mill, and provide theoretical guidance for optimizing the mill structure and improving grinding efficiency. The experimental vertical stirred mill is taken as the research object, a discrete element-fluid-structure coupling model is established, and the collision characteristics and its variation law along the axial direction from five aspects: collision frequency, normal and tangential collision energy, normal and tangential collision force are systematically study. The results show that the collision frequency between grinding spheres accounted for 90.5% of the total, much higher than the collision between grinding spheres and the cylinder, and play a dominant role in the grinding of ore materials. The tangential collision energy between grinding spheres is about 1.4 times that of normal collision energy, but the normal collision force is about 6.2 times that of tangential collision force. It can be concluded that the grinding effect of grinding spheres is more significant in the tangential direction. Based on the differences in the collision characteristics along the axial direction inside the cylinder, it is concluded that the grinding spheres located at the cylinder bottom to a height of 3/8 have high collision frequency, high collision energy and low collision force, which can effectively refine materials. However, the grinding effect in other areas is relatively low, allowing for rapid material classification and the overflow of materials that meet the particle size conditions from the cylinder.
- 1
-
Research on the Mining Sequence and Collaborative Processing Scheme of the Triangular ore Belt with Storage Holes
Abstract:
In response to the challenges of large-scale surface subsidence caused by the recovery of the ore body in the triangular ore belt of a certain silver lead zinc mine, based on the on-site engineering geological conditions, two sets of overall mining planning schemes were proposed, namely, the scheme of pre processing the ore deposit area and then mining the ore body, and the scheme of first mining the ore body and then processing the ore deposit area. A geological model was jointly constructed using CAD-3Dmine Midas, and numerical simulation methods were used to compare and select the stress field, displacement field, and plastic zone distribution of the corresponding models in each mining stage. The planning scheme I was found to be more conducive to controlling the ground pressure and stability of the mining area and the ore deposit area during the mining operation, reducing resource waste. Based on the numerical simulation results and mining technology conditions, a collaborative recovery plan for building a false top (bottom) and bottom was proposed, and the construction plan for the artificial false top (bottom) was determined. Combined with the random forest algorithm, a prediction model for the settlement of the artificial false top roof was constructed to continuously ensure the safety of underground ore mining in the area. The industrial test results show that the recovery rate of Cunlong ore reaches over 80%, creating a profit of about 5 million yuan.
- 1
-
3DEC simulation of response characteristics of surrounding rock of adjacent tunnel under blasting effect
Abstract:
To investigate the dynamic response characteristics of adjacent tunnels under blasting loads, this study employs the 3DEC discrete element simulation software to establish a Bonded Block Model (BBM) that accounts for the discontinuous nature of rock masses. The model simulates the vibration velocity field, stress wave propagation, and crack evolution in the surrounding rock of adjacent tunnels subjected to blasting. By analyzing the rock response under different blast rise times (10μs, 50μs, 100μs), the results reveal that: (1) A short rise time (10μs) leads to concentrated energy release, resulting in a higher peak particle velocity (PPV) of 6.5867 m/s but rapid attenuation, whereas a long rise time (100μs) promotes more uniform energy distribution, significantly increasing the PPV peak (53.981 m/s) and causing more pronounced cumulative damage to the surrounding rock. (2) The evolution of crack fractal dimension exhibits a two-stage pattern: a sharp initial increase followed by gradual growth. Under a long rise time (100μs), the final fractal dimension reaches 1.6236, indicating a greater extent of rock damage. (3) Based on stress wave propagation and PPV distribution, optimization strategies for blasting parameters are proposed: short rise times are suitable for efficient blasting, while long rise times require controlled charge distribution to minimize rock damage. The findings provide a theoretical foundation for the safe design and construction control of blasting operations in adjacent tunnels.
- 1
-
Experimental Study on Recovering Graphite from Graphite Tailings
Abstract:
In view of the present situation that the graphite in graphite tailings has not been fully recovered, the experiment of recovering graphite from a graphite tailings in Heilongjiang Province with fixed carbon content of 3.40% was carried out. The properties of graphite tailings were studied by chemical multi-element analysis, XRD analysis and optical microscope analysis. On this basis, the roughing condition test and stage grinding stage separation process test of graphite tailings were carried out. The results showed that graphite mostly coexisted as inclusions or adjacent to other minerals, and graphite particles varied in size, mostly existed in tailings of+0.09 mm. In order to fully dissociate graphite from graphite tailings and avoid sliming, multi-stage grinding and multi-stage separation processes should be adopted. When the grinding fineness is -200 mesh, the content is 29.52%, the flotation concentration is 20%, the amount of kerosene is 300g/t, and the amount of No.2 oil is 50g/t, the graphite coarse concentrate with fixed carbon content of 15.62% and recovery rate of 72.88% is obtained. Through closed-circuit flowsheet test, it was determined that graphite tailings were subjected to the technological flowsheet of "four-stage grinding, one roughing, five-stage cleaning, and return of middling", and graphite concentrate with fixed carbon content of 81.33% and recovery rate of 61.51% was obtained.
- 1
-
The game of deep-sea mining emission rules in the "region" and China's solutions
Abstract:
Deep-sea development is accelerating, and the conflicts between emission risks and legal regulations caused by deep-sea mining in the international subsea area need to be resolved urgently. To solve this problem, starting from the basic explanation of mining emissions, we will systematically sort out the game stage of mining emission rules within the "region" to reveal the dispersion and ambiguity of the current international law framework. By analyzing the application difficulties of the international legal system for mining emissions, the connection faults between domestic and international law, and the lagging environmental risk prevention mechanism, we will identify key difficulties in governance. Research and propose a coordinated mechanism for legal interpretation under the dynamic system, the entity construction of the cross-conventional organization collaboration mechanism, and the hierarchical design of risk prevention and emergency response mechanisms to achieve coordinated optimization of mining emission rules. Against the backdrop of China's strategic imperatives,?revising domestic deep-sea mining legislation, deepening regional collaboration, and spearheading the "negative list" proposal?will facilitate?a paradigm shift in rule engagement?– transitioning from adaptation to leadership.?This approach delivers?actionable solutions for navigating the interplay of negotiation and cooperation in regional deep-sea mining emission governance,?while concurrently establishing?a practical model for global governance.
- 1
-
Pilot-Scale Continuous Flotation Test Study on Comprehensive Recovery of Silver, Iron, and Manganese from a Silver Polymetallic Ore in Heilongjiang
Abstract:
For the efficient recovery of silver, iron, and manganese from a polymetallic silver ore in Heilongjiang Province (Ag 452.25 g/t, Fe 21.13%, Mn 6.42%), process mineralogy studies revealed that silver primarily occurs in sulfides while iron and manganese mainly exist in carbonate minerals (with minor iron hosted in magnetite). A combined flotation-magnetic separation process was developed, featuring "silver flotation - low-intensity magnetic separation for iron - high-intensity magnetic separation for manganese". Laboratory-scale closed-circuit tests achieved: silver concentrate grading 3,287.35 g/t Ag (85.82% recovery), iron concentrate with 60.74% Fe (79.85% magnetic iron recovery), and manganese concentrate at 15.03% Mn (76.65% recovery). In scaled-up continuous tests, optimized reagent dosages and circuit modifications improved results to: silver concentrate at 4,120.36 g/t Ag (88.75% recovery), iron concentrate grading 62.38% Fe (79.42% magnetic iron recovery), and manganese concentrate at 15.06% Mn (73.97% recovery). Tailings water treated with polyacrylamide flocculation sedimentation demonstrated successful reuse in the entire process, maintaining concentrate quality fluctuations below 3.0%. This research provides both theoretical and practical foundations for the comprehensive utilization of similar complex mineral resources.
- 1
-
Study on the Effect of New Vulcanizing Agent on the Sulfide Flotation Behavior of Azurite and Its Mechanism
Abstract:
The effect of new vulcanizing agent GX2 on the sulfide flotation behavior of azurite was studied by single mineral flotation test. The mechanism of vulcanizing agent on azurite was discussed by Zeta potential measurement, contact angle test, adsorption capacity test and X-ray photoelectron spectroscopy analysis. The results show that the maximum flotation recovery rate of azurite can reach 94.37% under the conditions of pulp pH=9, vulcanization time 2 min, butyl yellow dosage 120 mg/L, GX2 dosage 20 mg/L and 2#oil dosage 80 mg/L. GX2 acts on the surface of the azurite in the form of chemical adsorption, which enhances its electronegativity, and generates a hydrophobic Cu-S component on the mineral surface, which increases the adsorption amount of the collector on the mineral surface, thereby improving the sulfidation effect on the mineral surface.
- 1
-
Research on Transient Energy Suppression Methods for Overcurrent and Short-Circuit Protection in Intrinsically Safe Power Supplies for Explosive Atmospheres
Abstract:
In explosive hazardous environments, current-limiting intrinsically safe power supplies still face the issue of transient energy transfer to the load when semiconductor switching elements interrupt the overcurrent main circuit. To address this problem, this study proposes adding transient suppression components to the overcurrent protection circuit, which reduces the transient energy by slowing the rise rate of the short-circuit current. By analyzing the short-circuit discharge process, a mathematical model of the discharge was established. Multisim simulations of protection circuits with varying inductance values revealed a nonlinear relationship between inductance parameters and transient energy: increasing inductance suppresses the transient current amplitude, but excessive inductance prolongs the protection response time, leading to energy accumulation. An intrinsically safe power supply was designed and fabricated based on the short-circuit discharge model. Experimental results demonstrate that adding inductance effectively suppresses the short-circuit current and transient energy. With a 47μH inductor, the transient energy was reduced to 1.17μJ, representing a 33.9% reduction compared to designs without inductance. Further optimization with freewheeling diodes constrained the transient voltage peak within safe thresholds. This work provides theoretical and experimental foundations for transient suppression design in intrinsically safe power supplies.
- 1
-
Effect of loading rate on fracture behavior and crack propagation law of sandstone from mine roof
Abstract:
To reveal the loading rate effect of the roof fracture behavior, taking the roof sandstone of a typical mine as the research object, Brazilian splitting tests with a total of 5 loading rate grades within the range of 0.001-10 kN/s were carried out. The mechanical behaviors such as tensile strength, fracture characteristics, initiation stress, acoustic emission characteristics, and fracture microscopic morphology were analyzed. Based on the distribution of acoustic emission sources, the evolution law of internal damage cracks in the specimens under different loading rates was discussed. The results showed that for every 10 times increase in loading rate, the tensile strength increased by 0.64 MPa, but the ratio of cracking stress to tensile strength decreased, with values of 40.13%, 36.59%, 32.53%, 26.17%, and 15.81%, respectively, as the loading rate increased. For every 10 times increase in loading rate, the average size of fragments decreased by 0.229mm, the degree of fragmentation increased, and the distribution of fragment sizes became more uniform. Under lower loading rates, acoustic emission sources mainly occurred along the macroscopic fracture surface, while under higher loading rates, due to the initiation and expansion of cracks from multiple dispersed stress concentration areas, the distribution of acoustic emission sources was relatively dispersed. As the loading rate increased, the transgranular phenomenon at the fracture surface became more and more significant, transitioning from a single crack and straight form at the lower loading rates to multiple cracks and complex forms at the higher loading rates.
- 1
-
Fracture analysis of sandstone with single filled fracture under uniaxial compressionYE Tengfei1, YANG Daoxue1, ZHAO Kui1,2, YANG Anmin1, YIN Wenjie1
Abstract:
The existence of filling joints (filling fissures) in rock mass will change its mechanical properties and weaken the overall strength and stability of rock mass to a certain extent. Therefore, it is of great significance to study the mechanical response and failure mechanism of rock with different filling fissure dip angles and different fillings in view of the various forms of filling fissures that often exist in engineering practice. In this study, digital image correlation (DIC) and acoustic emission (AE) techniques were used to study the effect of different fracture dip angles and fillings on fracture behavior of fractured sandstone under uniaxial loading. The results show that the filling material makes the elastic deformation stage and brittle fracture characteristics more obvious; The increase of the strength of the filling material decreases with the change of the fracture angle; The elastic modulus of sandstone without filling increases with the increase of dip angle, and the elastic modulus after filling is not affected by dip angle. The principal strain field shows that the strain distribution of fractured sandstone is relatively uniform and thecrack propagation path is concentrated after the filler is added. When there is no filling, the failure mode of fractured sandstone with an inclination of 0°~15° is tension failure with wing shaped tension crack through, and the failure mode of fractured sandstone with an inclination of 30°~90° is shear failure with wing shaped shear crack through; Regardless of the fracture dip angle, the failure mode of fractured sandstone is tension shear composite failure with wing shaped tension shear crack through. The RA-AF distribution based on the sample also shows that when there is no filling, the crack evolution of fractured sandstone with an inclination of 0°~15° is mainly tensile crack, and the crack evolution of fractured sandstone with an inclination of 30°~90° is mainly shear crack; Regardless of the fracture dip angle, the crack evolution of sandstone filled with fractures is dominated by tensile cracks, supplemented by shear cracks.
- 1
-
Application of Raise Boring Machine and Remote Intelligent Control System in Slot Raise
Abstract:
As one of the key processes in the stage open stope and subsequent filling mining method, the quality of the slot raise directly affects the effect of the subsequent blasting to form the cutting groove, and ultimately affects the quality of large-scale caving during mining. In view of the problems of low intelligence, high safety risk and large occupational injury in the construction of traditional artificial sight distance operation raise boring machine, combined with the mining status and occurrence conditions of porphyry ore body in Shanxi Zijin, the existing construction mode of slot raise is optimized to realize the intelligent construction of slot raise. The intelligent operation process of raise boring machine is studied, and the dynamic optimization control technology of operation parameters is proposed. The "mountain climbing method" is used to realize the dynamic optimization of parameters, and the independent and efficient continuous drilling is realized through the remote intelligent control system based on 5G communication technology. The production practice shows that the raise boring machine equipped with remote intelligent control system can maintain high-precision hole guiding and reaming operation even in the rock stratum with fracture zone, and the deflection rate can reach 0.68%. The successful application of raise boring machine and remote intelligent control system in the unmanned construction of slot raise has a good reference for the unmanned construction of shaft in other scenes.
- 1
-
Research on the Comprehensive Treatment of Hidden Goaf in the Open-pit Slope of Dahongshan Iron Mine
Abstract:
Hidden goaf in open-pit mines poses a significant hazard to mine safety production. Taking the comprehensive treatment of hidden goaf in the open-pit slope of Dahongshan Iron Mine as an engineering case, a treatment approach of "blasting within the boundary and backfilling outside the boundary" was proposed. The stability of the goaf was analyzed using the "simply supported beam theory" and the "caving arch theory" for the inner and outer goaf areas of the open-pit respectively, determining the safe thickness of the goaf roof. Subsequently, the progressive failure mode of the slope containing goaf during open-pit mining was revealed using the 3DEC discrete element software. And the range of backfilling treatment and the threshold of backfilling body strength were obtained. Finally, the stability of the open-pit slope after comprehensive treatment was evaluated using Phase2 software. The results show that the safe thickness of the goaf roof for inner and outer boundaries of the open-pit are 20-30 m and 20-25 m respectively. With the staged mining of the open-pit slope, there is a gradual instability of the goaf roof leading to local slope collapse risk, necessitating backfilling treatment for the second and third layers of goaf within 30 m from the edge, with a required compressive strength of 20 MPa for the backfilling body. After backfilling, shear strain decreases and transfers inward, increasing the slope safety factor to 1.285, meeting the stability requirements. This study provides valuable guidance for similar treatment of hidden goaf areas in slopes.
- 1
-
Trajectory planning of shotcrete robot based on whale optimization algorithm
Abstract:
Shotcrete support is widely used in tunneling, with the advantages of low cost and high safety. The manipulator is the core part of the shotcrete robot. In order to improve the design theory, kinematics and trajectory planning analysis are carried out on a six-degree-of-freedom shotcrete manipulator configuration. And for the time-optimal trajectory planning of the manipulator, a trajectory planning method based on the improved whale optimization algorithm is proposed. By introducing the Circle chaos mapping, Cauchy perturbation strategy and the pheromone mechanism of the ant colony algorithm, the global search ability of the algorithm is enhanced, which effectively avoids falling into the local optimal solution, and significantly accelerates the convergence speed, while improving the efficiency and accuracy of the local search process. The improved algorithm enables the manipulator to reach the target posture more quickly, successfully shortening the running time by 56.7%, thereby further verifying the feasibility of the algorithm.
- 1
-
ZHANG Zhigui, TAN Baohui, ZHONG Min, et al. Downward layered approach type collodion filling method mining stability judgment method and application[J]. Metal Mine, 2021, (04):27-34.
Abstract:
In the mining process, the areas often encountered have fragmented rock masses and poor ore conditions, significantly affected by mining activities. For these areas, the backfill method is usually chosen for mining. However, improper process parameters during the stope backfilling can easily lead to rock failure. To achieve efficient and safe extraction of resources under fragmented rock conditions in the first mining area of a copper-gold mine, geological surveys were used to obtain rock mechanical parameters, which were then reduced and applied to a numerical model of the mine. Numerical simulation was used to focus on optimizing the process of the upward stoping backfill method, particularly regarding drift cross-section parameters, panel stoping spacing, and multi-layer collaborative stoping spacing. The feasibility of the optimized process was tested through on-site industrial trials. The study results indicate that the impact of changes in drift width on the roof varies with different roof media. To achieve safe and efficient mine production, the optimized cross-section size is determined to be 5m × 5m, with a multi-layer collaborative stoping vertical spacing of no less than 20m. The "three stope, one rest" approach is implemented within the panel, with a stoping spacing of 15m. Applying these optimized process parameters in on-site industrial trials enabled safe, efficient, and economical mining under unstable rock conditions in the first mining area, demonstrating the feasibility of the process optimization. This provides scientific evidence and technical support for resource recovery in the first mining area.
- 1
-
Simulation of Motion Characteristics of Particle Groups with Different Magnetic Properties Based on EDEM-Maxwell Coupling
Abstract:
In order to investigate the motion law and separation mechanism of different magnetic particles in the magnetic roll separator process, based on the gradient of the magnetic field and the specific magnetic susceptibility of the particles, a magnetic computation model was established, and a coupled simulation method of electromagnetism and particle kinematics was realized. ANSYS Maxwell software was employed to simulate the magnetic field distribution of the magnetic roll separator system. After obtaining the magnetic field vector data, it was imported into the simulation environment through EDEM field management. The secondary development, based on C++ API, was carried out to extend the function of EDEM to simulate the particle behavior under magnetic force. The simulation results demonstrate the efficacy of the coupled simulation method in simulating and analyzing the influence of key process parameters, such as the speed and size of magnetic roll particles, on the motion trajectory and drop distribution of particles with different magnetism. The simulation results also successfully differentiate the kinetic behavior of magnetic particles and non-magnetic particles in the separation process. The efficacy of the simulation method employing ANSYS Maxwell coupled with EDEM in simulating the magnetic separation process is substantiated by these findings. The test results reveal the factors influencing the motion characteristics of magnetic particles and provide a substantial theoretical foundation and technical support for enhancing magnetic separation technology.
- 1
-
Study on the Influence of Directivity of Near-Fault Ground Motion on Seismic Response and Seismic Stability of the Slope
Abstract:
Due to the significant difference of the near-fault ground motion intensity characteristics in different directions, three kinds of ground motion intensity parameters were chosen to compare the variability of ground motion intensity in different directions with typical near-fault seismic recordings as an example; based on OpenSees finite element software, the differences of the seismic response of slopes under the action of earthquakes in different directions were analyzed; considering the strain softening characteristics of the soil, the influence of directional effects of ground shaking on the seismic stability of slopes was explored. The results show that: the variability of the peak acceleration PGA in different directions reaches 62.5%; the displacement response of the slope top under the action of the direction where the maximum value of the PGA is located increases by 20.5% and 86.5%, respectively, compared with the two components of the measured horizontal ground motion records; the variation of the slope safety coefficients under the action of earthquakes of different directions ranges from 0.93 to 1.15, and the neglect of the directionality of earthquakes may overestimate the seismic capacity of the slope and increase the seismic stability of the side slope. Neglecting the seismic directionality may overestimate the seismic capacity of the slope and increase the risk of seismic destabilization, and the research results can provide a reference for the seismic design of slopes and disaster prevention and control.
- 1
-
Prediction for compressive strength of cemented tailings backfill based on shrinkage performance
Abstract:
To reduce the impact of fluctuations in the dosage of cementitious materials and control solid content(SC) of backfill slurry in the filling and batching system on the strength prediction of the stope backfill, the shrinkage characteristics of the unclassified tailings backfill slurry, which are strongly correlated with these two factors, were selected as the research object. Static settlement tests and uniaxial compression tests were conducted on the cemented backfill slurry with different cement-tailings ratios(CTRs) (1:4, 1:8, 1:20) and solid mass fraction (70%, 72%, 74%, 76%). The random forest algorithm was selected to calculate the feature importance scores of different factors, and a compressive strength prediction model was constructed based on the shrinkage ratio(SR). The model was validated by combining in situ measured data from an upward splitting layer mining stope in a lead-zinc mine. The results show that: 1) The SR of backfill slurry with different CTRs decreases sharply after the SC increases to a certain threshold. The SR of slurry with a CTR of 1:20 (solid mass fraction increased from 74% to 76%) decreases by 49.15%, and this SC threshold continues to decrease with the increase of CTR. The CTR of 1:8 was between 72% and 74%, while the CTR of 1:4 shows no threshold within the measured SC range; The increase in compressive strength of the backfill shows a trend of first decreasing and then increasing with the rise of SC, and the critical SC range for this trend is 74% to 76%; 2) By training a random forest model and calculating the feature importance scores of each factor, it is identified that the CTR has the greatest impact on the compressive strength of the backfill(93%), and the SR(5.6%) has a greater effect on the compressive strength than the SC(1.4%); 3) The engineering application shows that the prediction method of stope backfill strength based on SR has smaller errors than the prediction of SC of backfill slurry.
- 1
-
Strength deterioration and acoustic emission response characteristics of limestone under mine water erosion
Abstract:
Acid mine water erosion can significantly weaken the mechanical properties of limestone, but the impact on its micro failure mechanism is not clear. Through nuclear magnetic resonance (NMR) and uniaxial compression acoustic emission tests, the response laws of limestone pore evolution, mechanical properties and acoustic emission parameters (event rate, dominant frequency, crack type) under different erosion time (14~56 d) were studied. The results show that: In the process of mine water erosion, the porosity of limestone increased from 0.26% in the state of non erosion to 9.13% in 56 days of erosion; In the uniaxial compression test of limestone, the strength, peak strain and elastic modulus of limestone gradually decreased with the increase of erosion time, and its peak strength decreased by 29.41% compared with the non eroded specimen. The acoustic emission event rate and energy rate increase with the increase of erosion time. With the increase of erosion time, the number of low dominant frequency acoustic emission signals increases gradually, while the high dominant frequency acoustic emission signals show a decreasing trend. The proportion of shear microcracks in limestone gradually decreases with the increase of erosion time, while the proportion of tensile microcracks gradually increases from 31.61% to 57.92%. Therefore, the mine water erosion leads to the gradual increase of the porosity of limestone specimens, the aggravation of the propagation of microcracks and pores, and the significant decline of its mechanical properties. The research results provide theoretical support and technical guidance for the safe and efficient exploitation of non-ferrous metal resources in water rich environment.
- 1
-
Experimental study of oxidative and combustion characteristics of gas coal under the effect of pre-oxidation and water immersion
Abstract:
In order to explore the influence of the combined effects of pre-oxidation and water immersion on the characteristics of coal oxidation combustion, the thermogravimetric analysis experiments were carried out with gas coal under different pre-oxidation temperatures and water immersion conditions. The characteristic temperature, activation energy and reaction rate of coal oxidation combustion under different pre-oxidation temperatures and water immersion conditions were analyzed, and the action mechanism of pre-oxidation and water immersion conditions on coal oxidation combustion was discussed. The results show that compared with the unoxidized raw coal, the characteristic temperatures of the combustion weight loss stage of coal under the pre-oxidation at 150 ℃ and 240 ℃ decreased by 2.8% and 0.2% respectively, and the activation energy decreased by 4.9% and 48.7% respectively. The spontaneous combustion risk of coal is enhanced, and it is easier to reignite. The coal pre-oxidized at 240 ℃ and then re-immersed in water will significantly reduce the characteristic temperature and activation energy of oxidation combustion. Compared with the coal pre-oxidized at 240 ℃, the characteristic temperatures of oxidation weight gain stage and combustion weight loss stage of coal after pre-oxidation at 240 ℃ and subsequent water immersion treatment decreased by 65.2 ℃ and 16.3 ℃ respectively, and the activation energy of combustion weight loss stage is reduced by 7.8 kJ?mol-1, increasing the risk of coal spontaneous combustion. The combustion reaction rate of coal samples increased after pre-oxidation and decreased after re-immersion treatment, especially the combustion reaction rate of coal after high temperature(240 ℃) pre-oxidation treatment. When coal undergoes high-temperature oxidation, it is not advisable to directly inject water for cooling. Instead, other fire prevention and extinguishing measures such as injecting low-temperature nitrogen and liquid carbon dioxide should be prioritized.
- 1
-
Analysis and evaluation model of influencing factors of mine safety production
Abstract:
In view of the characteristics of many influencing factors of mine safety production, complex relationship and fuzzy quantitative evaluation, an analysis and evaluation model of influencing factors based on dematel-ism-cm is proposed. Firstly, a comprehensive evaluation system is constructed from the five dimensions of personnel, equipment, environment, management and technology; Then, the dematel-ism method is integrated to identify the key influencing factors, draw a multi-level structure diagram, and obtain the index weight value according to the centrality of the influencing factors; Finally, taking a lead-zinc mine in Hunan Province as the research background, the safety production risk level was determined. The results show that the emergency management system, on-site operation environment, equipment evolution degree, safety production responsibility system and safety protection device are the key factors affecting the safety production of the mine, and the mechanization degree of equipment, equipment evolution degree and key technology application are the fundamental factors; Based on the comprehensive cloud chart, it is determined that the mine safety production risk is at a low level (level IV), which is in line with the engineering practice, and verifies the reliability and applicability of the model, which can provide theoretical guidance for the safety management of mining enterprises.
- 1
-
Study on Characteristics of Rock Fragmentation Energy Under Double Disc Cutters Action of TBM in Deep Underground
Abstract:
With the depletion of shallow resources and increasing demand for deep engineering, the work of tunnel boring machine (TBM) face technical and theoretical challenges in achieving efficient rock fragmentation under complex deep-ground conditions with high geostress.Focusing on the energy evolution and dissipation mechanisms during rock fragmentation by dual-disc cutter of tunnel boring machine in deep environments, the research established a numerical model of dual-cutter rock intrusion using Abaqus nonlinear finite element software. The model analyzed rock mass damage-failure processes and energy evolution characteristics under variable confining pressures, while investigating the effects of confining pressure, uniaxial compressive strength (UCS), blade width, and cutter spacing on energy dissipation. The results show that confining pressure significantly alters rock damage patterns, and at confining pressures <15 MPa, longitudinal damage propagation dominates, while lateral damage accelerates at higher confining pressures, leading to shear-tensile composite fracture modes. Energy dissipation rates peak at 25 MPa confining pressure, marking the earliest transition to stable energy dissipation stages. A nonlinear correlation exists between rock UCS and energy consumption. When penetration depth ≥1 mm, the lowest energy dissipation rate occurs at UCS=105 MPa, beyond which dissipation increases dramatically. Optimal blade width for stable rock fragmentation is 15 mm, and cutter spacing optimization requires dynamic adjustments based on penetration depth: at penetration ≤1 mm, 80 mm spacing achieves maximum energy efficiency, but 100 mm spacing significantly enhances energy dissipation inner rock mass for penetration >1 mm. The research results provide a theoretical foundation for energy-efficient TBM tunneling in deep engineering projects.
- 1
-
Research on anchoring performance of nanocomposite grouted anchors based on OFDR technology
Abstract:
In order to investigate the effect of nanosilica (NS) on the performance of ultrafine cement and to evaluate its application in grouted anchors. The test was conducted using ultrafine cement with an average particle size of 22 μm and 8-15 nm NS sol, the anchoring surrounding rock was high-strength unweathered siltstone, and high-strength rebar anchor rods with a diameter of 20 mm and a length of 1.4 m were used, and OFDR fiber-optic technology was used to realize the strain monitoring during the pullout process. Test groups with different NS dosage were set up, and the tests of fluidity, setting time, compressive and flexural strength of the nodular body, SEM microstructure and pullout performance were carried out systematically. The results show that: the addition of NS will reduce the slurry fluidity and setting time, and improve the early hydration reaction rate of the material; at the appropriate amount (2%), the compressive and flexural strength of the nodule body reaches the optimum, and the microstructure is more dense; the pullout test and OFDR fiber monitoring show that the peak bearing capacity of the grouted anchors after the addition of NS is increased to 210 kN, and the load-displacement curves show more ductility and higher residual strength, and the anchors' peak bearing capacity is increased to 210 kN, with a higher residual strength. The load-displacement curve showed stronger ductility and higher residual strength, and the strain of the anchor rods was uniform, and the local strain mutation was reduced. This study verifies the feasibility and effectiveness of nanocomposite grouting materials in improving anchorage performance, and provides technical support for the optimization of anchorage systems in geotechnical engineering.
- 1
-
Structural Optimization of Oscillation Cavity in Self-Excited Pulsed Jet Nozzles
Abstract:
Self-excited oscillating pulsed jet nozzles convert continuous jets into pulsed jets, which effectively enhance rock-breaking efficiency by creating periodic "water hammer" damage. The nozzle oscillation chamber, a crucial component for jet morphology control, lacks comprehensive theoretical research on its structural parameters, and its current linear structure suffers from energy dissipation, limiting jet performance. This study investigates the impact of cavity aspect ratio (cavity length L/upper nozzle diameter d1) on the external flow field pulsed jet performance, aiming to identify the optimal aspect ratio range. Furthermore, the dynamic relationship between the low-velocity region inside the cavity and the jet performance is analyzed from the perspective of flow field structure. The oscillation chamber wall shape is optimized using Bezier curves. Rock-breaking drilling experiments are conducted to compare the performance of the nozzles with the original and optimized oscillation chamber wall shapes, validating the optimization effect. The results demonstrate that the optimized oscillation chamber significantly reduces the internal low-velocity region, leading to a 17.02% increase in average velocity and a 16.74% increase in peak velocity in the external flow field. The drilling diameter, depth, and volume caused by the pulsed jet impact on rock are increased by 25.82%, 24.27%, and 18.32%, respectively, indicating a substantial improvement in the performance of the self-excited oscillating pulsed jet nozzle.
- 1
-
Study on the influence of detonation sequence on the effect of parallel hole cut blasting in deeply buried roadways
Abstract:
To address the low blasting efficiency in deep buried roadway excavation, this study investigates the influence of detonation sequence on straight-cut blasting effectiveness under high-stress conditions. Physical model experiments simulating explosive blasting were first conducted using metal wire electric explosion technology under high-stress conditions. The strain field evolution and crack propagation processes during cavity blasting were captured through digital image correlation (DIC) combined with ultra-high-speed photography. Additionally, the cavity formation characteristics under different detonation sequences were analyzed using 3D scanning. Numerical simulations were further employed to examine the impact of detonation sequence on damage evolution during cavity blasting under high stress conditions. Results reveal that when primary blast holes are oriented along the maximum principal stress direction, circumferential strain around empty holes significantly increases, facilitating the formation of penetrating cracks. The detonation sequence critically regulates cavity morphology, with priority detonation of boreholes along the maximum principal stress direction notably improving damage zone distribution and reducing residual material at hole bottoms. This study proposes an optimized detonation sequence strategy based on principal stress direction determination, providing theoretical guidance for efficient blasting excavation in deep metal mine roadways.
- 1
-
Research progress of mine ecological restoration based on knowledge graph analysis
Abstract:
Hotspots and development trends within the mine ecological restoration field were investigated to explore key research focuses and evolving directions. Utilizing tools such as VOSviewer, CiteSpace and SCImago Graphica, a visual analysis was conducted on key aspects of 692 English publications and 298 Chinese publications sourced Web of Science (WOS) and China National Knowledge Infrastructure (CNKI) datasets. These analyses encompassed annual publication trends, geographical and institutional distributions, keywords, and other critical metrics. The characteristics and differences among various mine ecological restoration concepts were also discussed, as well as those of different key restoration technologies. There has been a consistent increase in both domestic and international publications in this field. Frequent collaboration among different countries has led to the formation of a research network with China as the primary core and the United States, Australia, Spain, and other Western countries as secondary cores. International high-output institutions collaborate closely, while domestic high-output institutions lack significant connections. Keyword analyses from both English and Chinese publications reveal key research foci, including coal mine restoration, phytoremediation technology, heavy metal soil remediation, microbial mechanism research, restoration effectiveness evaluation, and carbon neutrality goal implementation. Future research directions should prioritize the restoration of mine ecological systems comprising soil, microorganisms, and plants; the application of emerging technologies such as unmanned aerial vehicle aerial surveying and machine learning algorithms in restoration modeling and effectiveness assessment; and practical strategies for achieving mine ecological restoration under the framework of carbon neutrality. Mine ecological restoration research is currently experiencing a phase of explosive growth. To advance this field, China should integrate macro-level monitoring with micro-level research, leverage innovative technologies, foster interdisciplinary and cross-sector integration, enhance inter-regional cooperation among institutions and researchers, and establish robust mechanism to support sustainable progress in mine ecological restoration.
- 1
-
Stope Size Optimization in High In-situ Stress Stratified Orebody of Sishanling Iron Mine
Abstract:
To address the stability challenges of stopes under high in-situ stress and complex geological conditions in deep mining operations, this study investigates key technological approaches for the safe and efficient extraction of stopes. Taking the Sishanling Iron Mine as the engineering background, a collaborative optimization method integrating theory, empirical data, and numerical modeling is established for stope structural parameter design. First, the Mathews stability graph method is applied, using corrected Q-system values and shape factors to preliminarily determine the safe exposure area and pillar size. Second, through engineering analogy, stope geometry and roof span parameters are refined based on empirical data from similar domestic and international mines. Finally, a three-dimensional discrete element numerical model is developed to simulate stope excavation under three design schemes. Quantitative evaluations of stress distribution, displacement, plastic zone volume, and the number of tensile contact failures are conducted to identify the optimal configuration. The results indicate that the optimal stope dimensions are 20 m (width) × 80 m (length) × 60 m (height). Under this scheme, roof subsidence (1.76 cm) and sidewall displacement (4.46 cm) remain below safety thresholds, while the plastic zone volume (23543 m3) and number of tensile contact failures (2157) are significantly reduced compared to the other schemes. The results also reveal that roof failure is predominantly tensile, while sidewall failure is characterized by a mixed tensile-shear mode due to stress redistribution. These findings provide a quantitative basis for support design and hazard mitigation. The integrated multi-method optimization framework offers a scientific foundation for stope parameter design and presents valuable engineering insights for kilometer-deep underground mines.
- 1
-
Design and Research of Safety Intelligent Pipeline Oil Transportation System for Underground mine
Abstract:
In order to research the safety design and intelligent design of the vertical oil transportation system in underground mines, a numerical relationship model between the maximum thrust and the length of a single rod during installation, as well as a dynamic vibration analysis model for vertical oil pipelines with different cross-sectional sizes and lengths, were established; A numerical model of water hammer effect and pressure relief transportation in oil transportation system was established, and the dynamic response characteristics of water hammer pressure were studied and analyzed under different oil flow rates and valve closing times. The results indicate that when the length of a single pipeline is at a specific value, the installation thrust increases sharply with the increase of pipeline diameter; The use of pipeline sand filling method can reduce the vibration caused by bubble excitation in the main pipeline; Reducing the oil flow rate or increasing the valve closing time can effectively reduce water hammer pressure. At the same time, design schemes such as intelligent refueling technology, intelligent scheduling technology, intelligent monitoring technology, intelligent fire protection and automatic fire extinguishing technology were proposed, which play an important role in the in-depth study of the safe and intelligent design of pipeline oil vertical transportation systems.
- 1
-
Evaluation of rockburst proneness of sandstone based on fuzzy mathematics method
Abstract:
With the increase of mining depth, the combined action of high ground stress and complex geological environment leads to frequent rock burst disasters. However, there is a lack of comprehensive evaluation method considering the influence of multiple factors to determine the tendency of rock burst. Based on the test of rock mechanics parameters of an iron ore in Xinjiang, the differences of rock burst tendency evaluation results of four single index rock burst evaluation methods are compared and analyzed. On this basis, a rockburst proneness evaluation index system including strength brittleness coefficient B, improved brittleness coefficient BIM, maximum storage elastic strain energy and strain energy index W is constructed. A comprehensive evaluation method of rockburst proneness based on fuzzy mathematics method is established. The influence of each index on rockburst risk is analyzed by entropy weight method, and the weight coefficients are 0.30,0.21,0.24 and 0.25 respectively. The practice shows that the evaluation results of the multi-index comprehensive evaluation method of rockburst tendency based on fuzzy mathematics method are basically consistent with the on-site damage situation. The research results can provide theoretical basis and technical support for mine safety production and rockburst prevention.
- 1
-
Research on two-layer transportation path planning for complex terrain environments in mines based on improved A * and ISSA algorithms
Abstract:
The current mining car path planning algorithm generally faces problems such as low search efficiency and long planned paths when facing complex terrain in mines. Designing an efficient and accurate path planning method has become an urgent problem to be solved. The research aims to improve the computational efficiency of path planning, shorten the length of the planned path, and enhance the adaptability of the algorithm in complex environments by optimizing the search strategy of the algorithm. To this end, an innovative two-layer path planning scheme has been proposed. The upper layer uses an improved A * algorithm to preliminarily plan the paths between nodes, while the lower layer uses an improved sparrow optimization algorithm for overall path optimization. Among them, the study innovatively introduced dynamic weighting coefficients to dynamically adjust the weights of heuristic functions in the A * algorithm, in order to accelerate the path search process. Simultaneously, the traditional sparrow optimization algorithm was innovatively optimized using Logistic Tent chaos, lens imaging reverse learning mechanism, and Levy flight strategy. The results show that the improved sparrow optimization algorithm has a shorter distance in the path planning scheme of mining maps, and there is no phenomenon of detours. Meanwhile, the algorithm converges to 8.26361E+08 after only 17 iterations in solving the path energy consumption target value. And the lowest path cost is only 9.56382E+02, which is significantly better than other algorithms. The improved sparrow optimization algorithm proposed in the study can effectively optimize the path in a shorter number of iterations, reducing the energy consumption and cost of the path. Provided important technical support for the optimization of transportation systems in complex terrain environments of mines.
- 1
-
Study on Prediction of Surface Subsidence Range in Caving Mining of Metal Mine
Abstract:
Application of caving method often causes large-scale strata movement and surface deformation, which poses a serious threat to the safety of surface buildings, traffic facilities, basic farmland and residents. Based on the numerical simulation, the surface subsidence is obtained preliminarily. Combined with the characteristics of caving mining, an improved Weibull distribution method for predicting subsidence in caving mining of metal mines is put forward through theoretical analysis. Considering the randomness and variability of mechanical parameters of rock mass, the concept of reliability is used to predict and analyze the surface subsidence range. Finally, the analysis results are verified by similar simulation tests. The results show that the relationship between the sizes of subsidence ranges predicted by the three methods is: numerical simulation
- 1
-
Development and Application of Spatio-temporal Coordinated Multi-equipment Unmanned Operation System for Key Processes in Tongkeng Mine
Abstract:
Safe, green, and efficient mining is a primary focus in the development of underground metal mines in the new era. To ensure national resource strategy security and address challenges such as the prevalence of small to medium-sized mines, complex orebody geometries, and difficulties in safety management during mining operations, a spatiotemporal collaborative approach integrating mining processes and critical operations is proposed. This approach is tailored to the complex fragmented orebody and multi-level, multi-operation scenarios at Tongkeng Mining. It is based on sublevel open stoping with subsequent backfilling as the primary mining process, leveraging unmanned and minimally manned operations in key processes such as drilling, blasting, loading, and crushing. By employing comprehensive wireless positioning network coverage for cross-temporal red-zone interaction and a multi-equipment data-sharing platform as a collaborative safeguard, a spatiotemporal collaborative safety scheduling and management platform has been constructed. This model introduces a novel mode of continuous unmanned and minimally manned mining operations in underground metal mines. The study serves as a reference for interdisciplinary advancements in mining processes, management, and equipment, contributing significantly to the intelligent technological progression of underground metal mining. It holds great importance in promoting unmanned and minimally manned operations and the intelligent development of equipment in underground metal mines.
- 1
-
Research on strength damage prediction model of freeze-thaw sandstone based on machine learning
Abstract:
Sandstone in cold area is especially sensitive to freeze-thaw action, and its strength damage has become a research hotspot. Aiming at the complicated problem of traditional experimental research process, a strength damage prediction model of freeze-thaw sandstone based on machine learning is proposed. By means of literature research and other methods, 117 sets of experimental data on strength damage of sandstone after freeze-thaw cycle are selected as the data set, including 6 characteristic variables such as longitudinal wave velocity Vp, dry density ρd, saturation density ρsat, cycle number n, freeze-thaw period T and strength loss rate η. Among them, Vp, ρd, ρsat, n and T are taken as input features of the model. η, as the output feature of the model, is used to predict the strength damage of sandstone after freeze-thaw cycle by using six machine learning models such as decision tree, and the performance of the six models is evaluated by four commonly used evaluation indexes such as R-square value. The results show that the four evaluation indexes of CatBoost model are all the optimal values in the six models. The R-square value of the training set and the test set reached more than 0.93, the MAE values were 0.008 and 0.028, the MSE values were 0.000 and 0.002, and the RMSE values were 0.015 and 0.039, respectively. The model has stronger generalization ability, and has excellent prediction ability for the strength damage of sandstone after freeze-thaw cycle. The calculation parameters of CatBoost model were optimized by Bayesian optimization algorithm. Three key parameters, namely the number of iterations, the maximum depth of tree and L2 regularization value, were found to have a decisive impact on the prediction effect of the model, and the final model was determined. The importance of the contribution of feature variables to the model was analyzed as follows: n>T>ρd>ρsat>Vp. The research can be applied to rock mechanics engineering practice in cold area.
- 1
-
Mechanism of The Effect of Different Magnetization Times on The Reverse Flotation Behavior of Fine-grained Hematite Ore
Abstract:
To investigate the impact of varying magnetization durations on the reverse flotation of fine hematite, water, reagents, and pulp were subjected to magnetization for different time periods. The mechanism of magnetization time on reverse flotation of hematite was elucidated by measuring the solution's conductivity and surface tension, the viscosity of the solution and slurry, and the changes in IR and Raman spectra on the surface of ore particles. The results showed that the magnetization effect was optimal at a magnetization time of 8 min, and the magnetized water, starch, and slurry could increase the hematite recovery by 2.3%, 4.16%, and 3.84%, respectively, while the magnetized dodecylamine decreased the hematite recovery by 3.56%. The magnetization treatment enhances solution conductivity, thereby increasing the solubility of the agent and the concentration of electrolytes in the solution. It also elevates viscosity, which intensifies the efficacy of the inhibitor and suppresses the upward flotation of hematite particles. Additionally, it reduces the surface tension of the solution, facilitating quartz adhesion to bubbles and improving the recovery rate in hematite reverse flotation. Magnetized water, magnetized starch and magnetized pulp all promote the adsorption of starch on the surface of hematite. Magnetized dodecylamine inhibited its adsorption on the surface of hematite. Infrared spectroscopic analyses demonstrated that magnetization substantially modulates the interaction between the agent and the mineral surface, consequently affecting the adsorption quantity of the agent on the mineral surface.
- 1
-
Experimental Study on Enrichment of Kaolinite From Coal Slime via Integrated Classification-Flotation Process
Abstract:
Coal flotation tailings, as a low-value product of coal preparation plant, is rich in potential resources such as kaolinite. In this study, coal slimes from Malan Coal Preparation Plant was used as an experimental object. The mineral composition and particle size distribution was analyzed. The influence of flotation time, reagent consumption on coal middlings recovery, and the structure and operation parameters influence of hydrocyclone on classification were researched. Three flowsheet experiments involving 3-stage classification and floatation were compared and a flowsheet of 3-stage classification combined with coarse and fine flotation was proposed to be the most suitable process for kaolinite enrichment from coal slime. It was found that the main minerals in coal slime are kaolinite and quartz. At the consumption of 1500g/t collector and 150g/t frother, collecting 5 min froth, the tailing ash can reach 80.11%. At a given feeding pressure, small hydrocyclone showed better enrichment effect. The flowsheet of 3-stage classification combined with coarse and fine flotation can produce a kaolinite product with a yield of 20.26% and a grade of 78.88%, a coal slime middling with a yield of 41.85% and ash of 33.87%. About one third of the product is of high ash content (82.45%) and coarse particle size, which can be discarded directly. This study provides a new technical approach for the upgrading and the resource utilization of flotation tailings in coal preparation plants.
- 1
-
Optimization of mining sequence for stopes in panel of mining in transition from open-pit to underground at Sijiaying Mine
Abstract:
Based on the background of the application of stage open-stope with subsequent filling mining method of mining in transition from open-pit to underground in Sijiaying open-pit mine, three mining sequence schemes of the panel stopes from "one side to the other side", "center to both sides" and "both sides to the center" were proposed. The numerical simulation method was adopted to study the distribution characteristics of the stress field, displacement changes, and plastic zone expansion laws of the panel stopes of surrounding rock under different mining sequences. Finally, the "center to both sides" mining sequence scheme was obtained as the optimal one for this mine. The results show that under the three mining sequence schemes: (1) the post-stress release compressive stress value of the surrounding rock of the panel stopes, the tensile stress of the surrounding rock and the maximum displacement value generated inside the surrounding rock all show the variation rule of "center to both sides" < "both sides to the center" < "one side to the other side"; (2) under the stoping sequence scheme of "center to both sides", the compressive stress value after the stress release of the surrounding rock is 1.58 MPa, the maximum tensile stress is 0.35 MPa, and the maximum displacement value generated inside the surrounding rock is 37.7 mm, all of which are smaller than the other two schemes; (3) after the panel mining, the total volume of the plastic zone in the surrounding rock, and the volume ratio of the tensile plastic zone to the total plastic zone, show the same variation rule as the surrounding rock stress field and displacement field. Under the "center to both sides" scheme, the total volume of the plastic failure zone of the surrounding rock is 34.73×104 m3, and the volume proportion of the tensile plastic zone is 60.60%, which is also smaller than the other two schemes. The research results are of great significance for guiding the design of open-pit to underground mining and the future production of the mine.
- 1
-
Macro and micro mechanical properties and fracture criteria of fractured sandstone under chemical corrosion
Abstract:
In order to explore the dynamic mechanical response and microscopic deterioration mechanism of sandstone after chemical corrosion, the red sandstone after accelerated corrosion by distilled water with pH=7 and HCl solution with pH value of 5 and 3, respectively, was taken as the research object, and dynamic compression tests were carried out under five different impact pressures to study the effects of chemical solution corrosion on dynamic mechanical parameters, energy consumption ratio and failure characteristics of sandstone. In addition, XRD and SEM were used to reveal the corrosion process and degradation mechanism of the sandstone, and the changes of the microscopic fractal dimension before and after the corrosion of the chemical solution were obtained by using the box dimension fractal legal scale. The results show that in acidic environment, Muscovite and plagioclase in sandstone will produce new quartz and soft kaolinite, and the acidic solution will dissolve the cement components between mineral particles, resulting in significant changes in the contact mode between particles, and the fractal dimension of microstructure and damage amount increase with the decrease of pH value of solution. In addition, the acidic solution will also cause the mineral particles themselves to decrease in stiffness. The results show that the chemical corrosion will cause the sandstone structure to be loose and weak, and the mechanical properties will deteriorate in the process of dynamic compression, resulting in the phenomenon that the peak stress decreases and the peak strain increases with the decrease of the acidity of the solution. The corrosion effect of chemical solution on sandstone will also lead to the phenomenon of macroscopic fracture degree increase, energy dissipation ratio decrease and fractal dimension increase during the failure process, so that the failure form is transformed from tension failure to shear failure. The mechanism of macroscopic and microscopic degradation of sandstone by chemical solution under dynamic impact is proposed.
- 1
-
Study on the performance of CO2 absorption-mineralization reaction coupling fly ash with mixed amine solution
Abstract:
Fly ash, a byproduct of coal-fired power generation, demonstrates significant potential for carbon mineralization. To address the issue of low efficiency in direct CO2 mineralization using fly ash, a mixed amine solution of N-methyldiethanolamine (MDEA) and diisopropanolamine (DIPA) was employed to absorb CO2, thereby improving the subsequent CO? fixation efficiency. The effects of various MDEA/DIPA ratios, solid-to-liquid ratios, reaction temperatures, and reaction times on CO2 absorption and mineralization efficiency were systematically investigated. The results demonstrate that the MDEA/DIPA mixed solution outperforms single amine solutions, achieving the highest CO2 loading of 1.66 mol/L and a carbonation efficiency of 45.2% at an MDEA:DIPA ratio of 1:3, a solid-to-liquid ratio of 270 g/L, and a temperature of 45 °C. FT-IR, XRD, and TG analyses reveal that CO2 absorption results in the formation of CO32–, HCO3–, and carbamate species, while mineralization predominantly produces CaCO3 in the calcite form. The results indicate that the integration of CO2 absorption and mineralization using MDEA/DIPA and fly ash provides an effective approach for CO2 sequestration and fly ash waste disposal.
- 1
-
Research on Damage Mechanisms and Fractal Characteristics in Composite Rock Masses under Millisecond Delay Blasting
Abstract:
This study investigates damage distribution in composite rock masses under blasting-induced stress waves, the research employs LS-DYNA to establish a dual-borehole blasting model with two rock types: harder rock I and softer rock II, analysis focuses on how initiation sequence and delay time influence rock damage patterns.The study yielded the following conclusions:In composite rock masses, after the superposition of blasting stress waves, the stress waves in rock I will continue to propagate while overriding those in rock II.The effective stress in rock I exhibits a higher attenuation rate than in rock II, resulting in lower overall effective stress levels in rock I compared to rock II.In the composite rock mass, the effective stress between blast holes initially decreases before rebounding, with rock I consistently maintaining lower effective stress levels than rock II throughout the process. The fractal dimension of rock exhibits a non-monotonic response to delay time, initially decreasing before increasing with prolonged delays, when blast holes in rock I are initiated first, the resulting fractal dimension consistently exceeds cases where rock II holes detonate first. These findings provide valuable references for blasting construction in rock mass engineering under similar geological conditions.
- 1
-
Multi-factor Strength Optimization of Waste Rock-Tailings Cemented Backfill: Response Surface Methodology Approach
Abstract:
To optimize the mechanical strength performance of mine waste rock-tailings cemented backfill, this study employed the Box-Behnken design within the response surface methodology (RSM) to conduct a three-factor, three-level experimental investigation. The research systematically explored the synergistic effects of waste rock particle size (0–5 mm, 5–10 mm, 10–15 mm), mass concentration (84%, 86%, 88%), and sand-to-binder ratio (53%, 60%, 67%) on the uniaxial compressive strength of backfill at different curing ages (7 and 28 days). A traditional orthogonal test was also incorporated for comparative analysis. The RSM results revealed that waste rock particle size predominantly governs the early-stage strength of the backfill, while mass concentration significantly influences the later-stage strength. The synergistic interaction between particle size and mass concentration was most pronounced, jointly regulating the skeleton stability and interfacial bonding properties of the backfill. Experimental validation demonstrated high accuracy for the RSM-derived strength prediction models, with determination coefficients R2=0.9949 (7 days) and R2=0.9837 (28 days). The optimal mix ratio identified through RSM was waste rock particle size 5–10 mm, mass concentration 85.5%, and sand-to-binder ratio 58.6%. In contrast, the orthogonal test results indicated that particle size dominated both early- and later-stage strength development. This study confirms that RSM effectively deciphers nonlinear multicomponent coupling relationships and achieves significantly improved prediction accuracy compared to traditional orthogonal testing. The findings provide an optimized solution with both theoretical rigor and engineering applicability for enhancing structural stability control in green mining backfill systems.
- 1
-
Design Concept and Engineering Application of Open Stope Subsequent Backfill Mining with Remote-Controlled LHD and Flat Floor Structure
Abstract:
To address the challenges of complex stope preparation and difficulties in excavating haulage tunnels within backfill bodies in traditional open-stope subsequent backfill mining for thick ore bodies, this study proposes an innovative mining method combining remote-controlled LHD machines with a flat-bottom structure. Theoretical formulas were established to calculate the ore output ratio of remote-controlled LHDs, quantitatively analyzing the effects of ore dip angle, natural repose angle of fragmented ore, and stope dimensions on residual ore volume. An optimization method for stope length was developed to control the ore output of remote-controlled LHDs and ensure production efficiency. Using the Bangzhong Zinc-Copper Mine as a case study, the design methodology for stope structural parameters was detailed, along with field trial results. Industrial trials demonstrated a 21% reduction in stope preparation engineering quantity, a 12% decrease in ore loss, and a 22% ore output ratio for remote-controlled LHDs (theoretical value: 19.6%), while maintaining a comparable stope preparation-cutting-extraction cycle to conventional methods. This research provides an innovative solution for the safe and efficient mining of thick ore bodies.
- 1
-
Investigation into Deformation Mechanism and Stability Control of Deep Jointed Hard Roadways with Heterogeneous-Joint Finite Element Modeling
Abstract:
Scientifically and systematically revealing the instability mechanisms of surrounding rock in deep hard rock tunnels is crucial for the design and optimization of their support parameters. Focusing on the kilometer-deep marble tunnels at the Jinchuan mine, a continuous-discontinuous numerical simulation method was employed. A custom program for heterogeneous materials was developed using the built-in Voronoi joint network and Weibull distribution function within RS2 software. A heterogeneous-joint finite element model for the rock and rock mass was established, calibrating the deformation and mechanical parameters of the marble and revealing the deformation and failure laws of deep hard rock. Meanwhile,Considering the joint characteristics of the surrounding rock in the tunnel, a heterogeneous-joint finite element model for the tunnel was constructed, successfully replicating the failure characteristics of deep hard rock tunnels. A local support scheme was proposed to address the failure patterns of unsupported tunnels. The study indicates that: (1) The rock and rock mass models constructed based on the heterogeneous-joint finite element method effectively characterize the deformation and failure behaviors of deep hard rock. (2) The simulation results of the heterogeneous-joint finite element tunnel model correspond with the actual failure conditions observed in the tunnel, thereby validating the method"s effectiveness. (3) Following the implementation of the local support scheme, the maximum depth of the plastic zones on both sides of the tunnel was reduced by 62.9% and 58.0%, respectively. Additionally, the number of block and joint failures decreased by 83.0% and 74.5%, respectively, while the maximum deformation of the tunnel was reduced by 33.8%. These results demonstrate the reliability of the local support scheme. The research results provide a reference for the analysis of surrounding rock damage in deep hard rock roadway and expand the idea of controlling surrounding rock deformation in deep hard rock roadway.
- 1
-
Liu Wei1,4, Jiang Ke1,4,6, Sheng Jia1,4,5, Jiang Feifei2, Kou Yongyuan3, Zheng Bokun1,4, Li Dexi1,4, Liu Chang1,4(1. Changsha Institute of Mining Research Co.,Ltd,Changsha,Hunan 410012,China；
Abstract:
Filling industrial pumps are the most commonly used conveying equipment in long-distance transportation for mine filling. In practical applications, it has been found that when the pipeline has a large elevation difference or the conveying pressure is high, the conveying pump body and pipeline experience significant vibration. To study the load characteristics of filling industrial pumps during long-distance transportation, a load characteristic model for filling industrial pumps and pipeline transportation was established using AMEsim based on loop test data. Simulation studies show that as the pipeline length increases, the pipeline pressure increases linearly, but the rate of increase and decrease in pipeline pulsation decreases. When the flow rate remains constant, the maximum pressure at the pump outlet is approximately inversely proportional to the square of the pipeline diameter. Based on the load characteristics of filling industrial pumps, a shock absorber device with a pre-pressure surge tank based on the principle of gas energy storage was studied. The results indicate that as the volume of the pre-pressure surge tank increases, the pressure pulsation at the outlet of the filling pump decreases. When the volume of the surge tank is between 0.4 and 0.6 times that of the conveying cylinder, the difference in pulse pressure can be reduced by half. This conclusion was verified through industrial application tests. This research has good guiding significance for the study of conveying resistance of filling industrial pumps, the design of filling pipelines, and the research on vibration damping technology for filling pipelines.
- 1
-
Study on the Electromagnetic Wave Propagation Characteristics in Rectangular Roadways of Underground Mines
Abstract:
To optimize antenna deployment in mine wireless communication systems, this study employs the Shooting and Bouncing Ray tracing (SBR) method to establish a three-dimensional model of a rectangular roadway (5 m width × 3.4 m height). A multi-scale analysis of power attenuation characteristics for 0.9 GHz, 2.4 GHz, and 3.5 GHz frequency bands is conducted, systematically evaluating transmission distance, longitudinal cross-sections, and spatial distribution. The influence of antenna positioning on wireless transmission is further investigated. Results indicate that the 0.9 GHz band demonstrates superior transmission performance, with the average power of longitudinal cross-sections at varying distances exceeding 2.4 GHz and 3.5 GHz by 6.60–9.17 dBm and 10.49–12.63 dBm, respectively. The optimal horizontal antenna position is identified as 0.01–0.1 m from the roadway wall. When deployed adjacent to the sidewall (0.01 m), the power spatial distribution exhibits asymmetry, with received power on the transmitter’s side being 1–4 dBm higher than the opposite side. Additionally, stable and robust signal reception is achieved when the vertical height difference between transceiver antennas remains below 0.5 m. These findings provide critical insights for optimizing base station placement and antenna configurations in underground roadways, supporting the development of efficient and reliable mine wireless communication systems.
- 1
-
Foreign Object Detection in Coal Mine Conveyor Belt Based on Linear Deformable Convolution
Abstract:
To address the challenge of detecting foreign objects on coal mine conveyor belts, where the irregular shapes and indistinct features of these objects render existing machine vision methods ineffective, this paper proposes an enhanced YOLOv11 model. The improvements are threefold: First, a C3k2-LDC feature extraction module is developed using linear deformable convolution, endowing the model with the capability to extract features from irregularly shaped objects. Second, an edge enhancement module is introduced, employing a multi-scale feature fusion strategy to effectively strengthen the edge information of objects with weak features. Lastly, a WIoU-based loss function optimization scheme is proposed to mitigate the impact of low-quality data samples on training. Experimental results demonstrate that the improved YOLOv11 model achieves an mAP50 value of 90.2%, outperforming the RT-DETR, EfficientDet-D2, YOLOv8n, and YOLOv11s models by 4.0, 9.1, 7.4, and 5.7 percentage points, respectively. Heatmap analysis reveals that the enhanced model exhibits a higher focus on complex object features compared to the original model. In terms of lightweight design, the model's floating-point operations and parameters are 6.8×10^9 and 2.63×10^6, respectively, with an inference speed of 127 frames per second, enabling real-time foreign object detection while maintaining detection accuracy. This provides an innovative technical solution for the safety of coal mine production.
- 1
-
Study on the Application of Heavy Liquid Separation in the Recovery of Copper and Aluminum Particles from Spent Lithium Iron Phosphate Batteries
Abstract:
Based on the issue of low separation accuracy when recovering copper and aluminum particles from lithium iron phosphate batteries using wind gravity separation, a separation method is proposed. Involves heavy liquid separation for the copper-aluminum mixture obtained after crushing and screening the battery cells in a factory"s crushing separation system, and for the copper and aluminum particle products after wind gravity separation. The test results showed that when the heavy liquid density was 2.95 g/cm3 and the solid-liquid ratio was 0.35 g/ml, the aluminum recovery rate for the >0.630 mm copper-aluminum mixture was 96.99%, and the copper recovery rate was 99.72%. For the 0.630~0.104 mm copper-aluminum mixture, the aluminum recovery rate was 97.62%, and the copper recovery rate was 90.02%. For the copper particle products, the aluminum recovery rate was 96.44%, and the copper recovery rate was 99.83%. For the aluminum particle products with particle sizes greater than 0.630 mm, the aluminum recovery rate was 99.66%, and the copper recovery rate was 98.52%. For the 0.630~0.125 mm aluminum particle products, the aluminum recovery rate was 90.60%, and the copper recovery rate was 96.46%. Large particle raw materials could achieve copper and aluminum separation through heavy liquid separation, and the separation of small particle raw materials provided conditions for subsequent separation of black powder and metal particles.
- 1
-
Energy ResearchExperimental Study on the Relationship Between Drilling Energy and Rock Strength
Abstract:
Accurate testing of rock uniaxial compressive strength is the basis of support design and rock mass stability analysis. In this paper, through the indoor drilling test of rock with different strength, the energy conversion and dissipation in the drilling process are analyzed, and the relationship between various energy and rock strength in the drilling process is studied. The results show that: in the mechanical energy input by the bit, the torque work accounts for more than 95%, and the WOB work accounts for less than 5%. The input energy of the bit is mainly converted into the surface energy of drilling cuttings, with an average conversion rate of 95.6%, and the average conversion rate of thermal energy is 4.2%; The net specific energy for drilling and the uniaxial compressive strength of mortar specimens with varying strengths share a linear relationship. An equation correlating drilling specific work with material strength has been formulated. This equation has been substantiated through drilling tests conducted on concrete, sandstone, and granite, demonstrating a maximum discrepancy rate of merely 5.07%. The relationship between surface energy, thermal energy, acoustic energy and rock strength is obtained. The relationship between various energies and rock strength can be mutually verified. The rock strength measurement method based on drilling energy has good applicability.
- 1
-
Analysis and prospect of China's mineral resource exploitation and utilization situation
Abstract:
Under the intertwined influence of multiple factors such as slowing global economic growth, intensifying geopolitical conflicts, and accelerating energy transformation, the mineral resources market presents complex and ever-changing characteristics. In order to better grasp the current situation and development trend of China's mineral resource exploitation and utilization, and provide scientific basis for policy formulation, this article adopts a combination of quantitative and qualitative research methods, and comprehensively uses statistics, comparative analysis, SWOT analysis, etc. to conduct in-depth mining and analysis of domestic and foreign mineral resource market data. By sorting out key indicators such as mineral product output, price, investment, import and export, the operational situation of China's mineral resources market has been revealed; Comparing the exploitation and utilization of mineral resources between China and major economies around the world, clarifying China's position and characteristics in the global mineral resources market; Comprehensively analyze the exploitation and utilization of China's mineral resources from four aspects: advantages, disadvantages, opportunities, and threats, and accurately grasp the internal and external factors facing their development. Research has found that the global mining market will experience significant differentiation in 2024, with energy and mineral prices falling, non-ferrous metal prices mostly rising, and precious metal prices such as gold continuing to rise significantly. China's mining investment has increased. Geological exploration investment and fixed assets investment in the mining industry have maintained a high growth trend. Mineral resources development has significantly shifted to the west. Relevant indicators in the western region continue to rise in the proportion of the country. The diversified mining industry development pattern dominated by state-owned holding enterprises has become more reasonable, and the production efficiency of mining enterprises has continued to improve; The overall trend of mineral resource exploitation and utilization is characterized by an increase in quantity and a decrease in price. The national raw ore production continues to grow, but the prices of mineral products generally decline, resulting in a year-on-year decrease in the total output value of the mining industry, sales revenue of mineral products, and total annual profits and taxes of enterprises. Looking ahead to 2025, a slowdown in global economic growth and an increase in supply will lead to a weakening of the international market for bulk mineral products, resulting in differentiated price trends for different mineral products; Global geological exploration investment has declined, but domestic geological exploration investment is expected to continue to increase; The mining situation in China is expected to remain stable, but the economic benefits and profits of enterprises have declined; The energy transition will significantly drive the growth of demand for clean energy technology minerals, and the market value of key minerals is expected to reach $770 billion by 2040. To this end, China needs to fully leverage the advantages of a unified domestic market and internal economic circulation, and strengthen the real economy; Relying on technological innovation to promote the transformation and upgrading of the energy and mineral resources industry; Strengthen international cooperation to ensure effective supply of overseas mineral resources; Promote the sustainable exploitation and utilization of mineral resources, providing solid guarantees for high-quality economic development.
- 1
-
Effects of pick cutting angle on mechanical rock breaking efficiency under varying in-situ stress conditions
Abstract:
Non-explosive mechanical excavation mining has the advantages of small disturbance, high efficiency, low support cost and good roadway shaping effect compared with drilling and blasting method, and the optimal selection of cut-off tooth parameters is of great significance to efficient excavation. According to a metal mine -525m, -606m, -653m in the middle section of the hollow package hole stress relief method measured stress and dolomite marble surrounding rock mechanical test results to establish the PFC particle flow interceptor rock breaking model, in the three middle section of the stress level set up 90°, 60°, 45° three kinds of interceptor intrusion angle for unidirectional unloading of interceptor rock breakage numerical simulation analysis. The study shows that: with the increase of stress, the area of dense nuclei formed by the tooth breakage decreases, the length of the developed strip cracks decreases, the number of microcracks formed in the process of rock breakage decreases with the increase of stress, and the stress will hinder the rock breakage. x-direction traction force and y-direction cutting force of tooth breakage at 45° intrusive angle fluctuates less than that of the 60° and 90° intrusive angle and the cutting force is always kept at a higher level, and the cutting force generated by 45° intrusive angle is also higher than that of 60° and 90° intrusive angle. Moreover, the number of microcracks generated by the 45° intrusion angle is much larger than that of the other two intrusion angles. Combined with all the factors, the 45° intrusion angle has the optimal effect of rock breaking under all the three stress levels.
- 1
-
Research on the Consolidation Characteristics of Deep High-Sulfur Ore and the Measures for Preventing Consolidation during Mining Process
Abstract:
In response to the issues of resource waste and safety hazards caused by oxidation-induced consolidation during the mining of deep high-sulfur ores, this study took the high-sulfur ores from the Peak Mine as the research subject. The solidification characteristics of the ores were quantitatively analyzed using the gravimetric method, and experimental research was conducted on the prevention of sulfur-containing ore solidification using composite anti-solidification agents. Based on the experimental results, specific prevention and control measures for sulfur-containing ore mining were proposed. The results indicate that the degree of ore solidification is determined by the synergistic effects of sulfur content and other components. Increasing the contact pressure between ore particles accelerates the solidification process. During the 12-day experiment, the maximum weight gain of the ore samples reached 0.460%. A composite anti-solidification agent based on sodium bicarbonate (NaHCO3) and hydroxyethyl cellulose (HEC) demonstrated significant inhibition of solidification. When the mass ratio of the two components was 1:2 and the concentration was 2%, the anti-solidification coefficient reached 0.855, which represents a 14.8% improvement compared to single-component agents. Combining these findings, practical anti-solidification measures were proposed, including optimizing blasting parameters to control ore particle size, implementing staged continuous out-mining to reduce exposure time, and applying anti-solidification agents via spraying. These strategies provide a theoretical foundation and technical support for the safe and efficient mining of deep high-sulfur deposits.
- 1
-
Research on Multi-objective Optimization Scheduling Method of Trackless Rubber-Tyred Vehicles in Underground Coal Mines
Abstract:
To address the challenges of high costs, low vehicle utilization, and significant carbon emissions in manual scheduling of trackless rubber-tyred vehicles (TRTVs) in underground coal mines, this study constructs an intelligent scheduling model to synergistically optimize transportation efficiency and environmental performance. First, an MT-CVRPTW model integrating hard time windows, cargo taboos, and multi-vehicle type constraints is established. Second, a dual-objective optimization model aiming to minimize total cost and carbon emissions is formulated. An innovative PGA-ALNS hybrid optimization framework is proposed, combining a Parallel Genetic Algorithm (PGA) and Adaptive Large Neighborhood Search (ALNS). This algorithm achieves a balance between global exploration and local exploitation through collaborative optimization of PGA’s global population parallel evolution mechanism and ALNS’s dynamic destruction-repair operators. It further integrates a time-sensitive weight selection strategy and elite retention mechanism. Simulation results indicate that, compared to genetic algorithms and simulated annealing, the PGA-ALNS algorithm reduces total costs by 9.4%, decreases carbon emissions by 10.6%, achieves a vehicle actual load rate of 94.2%, and shortens computation time by 38.2%. This approach significantly enhances the economic and environmental performance of underground transportation, providing a quantifiable technical pathway for intelligent mine construction.
- 1
-
HUANG Yujiao, GU Hengguang, ZHANG Hanquan
Abstract:
Chalcopyrite and pyrite are the core components of sulfide mineral resources, and their sorting efficiency directly affects the comprehensive utilization level of sulfide resources. To address the issue of low flotation separation efficiency between chalcopyrite and pyrite, a new thiol based collector (930 reagent) is proposed for flotation experiments. The selective adsorption mechanism is revealed through Fourier transform infrared spectroscopy analysis, and its effectiveness is verified through actual mineral flotation experiments. Experiments have shown that the 930 reagent optimizes the selectivity of copper sulfur separation, providing a new reagent solution for sulfide ore flotation separation that combines high selectivity and environmental friendliness. It is of great significance for reducing smelting costs and reducing alkaline wastewater discharge.
- 1
-
Study on the Safety Thickness of Isolation Layer in an Iron Mine from Open-pit to Underground Mining
Abstract:
In order to determine the isolation layer thickness of an iron mine"s open-pit to underground mining project to ensure mine safety production, theoretical calculation and numerical simulation were used to explore the influence of underground ore body mining process on surface rock mass settlement and rock mass movement under different isolation layer thickness. The results show that the optimum range of the thickness of the isolation layer of the iron mine is 11.25~26.56m under the theoretical calculation method. The surface settlement and rock movement of the isolation layer with thickness of 15m, 20m and 25m were analyzed by numerical simulation method. The numerical simulation results show that the surface settlement displacement of surface structures, open-pit slopes and dump sites is small and meets the stability evaluation criteria of rock mass. Considering the safe mining of the mine and avoiding the loss of mineral resources, it is recommended that the thickness of isolation layer in this mine is 20m.
- 1
-
The energy consumption law of irregular ore particle crushing of under impact
Abstract:
To reveal the energy consumption patterns of irregular ore particles under impact crushing, six types of iron ore impact crushing tests were conducted using an improved drop weight impact tester to analyze the fractal characteristics of irregular iron ore fragmentation and the size effect on average fragment size, fractal dimension, and unit absorption energy to establish the energy consumption model of irregular single particle crushing. The results show that the average fragment size, fractal dimension, unit absorption energy all exhibit a power function relationship with initial isosphere diameter under the same impact conditions, the average particle size of the fragments gradually increases, and the fractal dimension and unit absorption energy gradually decrease as the diameter of the spherical particles increases. There is a increasing relationship with power function between unit absorption energy and average particle size of fragments. The relationship between the logarithm of unit absorption energy and fractal dimension shows a linear increase. Through the method of ore crushing tests of irregular single particle, the study established a relationship model between the unit crushing energy consumption of irregular iron ore particles and the initial size, average particle size of fragments, and fractal dimension, enriching the theoretical research on the energy consumption law of ore crushing.
- 1
-
Research on the Optimization of the Water-Encounter Durability of Steel Fiber Reinforced Concrete Support in a Certain Iron Mine Roadway
Abstract:
Aiming at the problems of cracking and insufficient durability of the steel fiber reinforced concrete support in a certain iron mine roadway in Yunnan when encountering water, a three-factor and three-level orthogonal test was designed, and water absorption rate and sulfate resistance erosion tests were carried out. The influences of the water-cement ratio (0.42, 0.45, 0.47), the content of steel fibers (2%, 3%, 4%) and the content of waterproofing agent (0.10, 0.12, 0.14) on the water absorption rate and the performance of sulfate resistance erosion were comprehensively evaluated to optimize the water-encounter durability of the material. At the same time, the optimal mixture ratio was applied to the actual support in the mine for construction inspection. The results show that: the water absorption rates of the steel fiber reinforced concrete under each optimized mixture ratio are relatively low. The content of the waterproofing agent has the most significant influence on the water absorption rate (range 1.73), and when the content is 0.14, the water absorption rate drops to 4.69%; when the content of steel fibers increases to 4%, the water absorption rate is the lowest (5.54%). In the sulfate resistance erosion test, the mass loss ratios of the test blocks are all negative values (-0.14%~-0.35%), and the compressive strength increases with the increase of the number of cycles. The content of the waterproofing agent has the greatest influence on the strength (range 22.7MPa); the mixture ratio 2 (water-cement ratio 0.42, steel fibers 3%, waterproofing agent 0.14) has the best comprehensive performance, with a water absorption rate of 4.54% and a compressive strength of 83.1MPa (an increase of 17.6%). The field application shows that after the support with mixture ratio 2, the displacement of the two sides of the roadway stabilizes at 25mm, and there is no significant leakage on the surface, which verifies the feasibility of the optimized mixture ratio.
- 1
-
Inversion Method of Large Range Mining-induced Stress Field in Deep Metal Mines Based on Microseismic Monitoring Technology
Abstract:
The frequent and intense adjustments of the surrounding rock stress field caused by large-scale multi-level and multi-stope strong mining in deep metal mines can easily induce engineering rock mass disasters such as wall falls and collapses. In response to the problems of high cost and poor timeliness of multi-point testing in the existing mining-induced stress field inversion process, based on the theory of geophysics and microseismic monitoring technology, a mining-induced stress field inversion method for deep metal mines has been developed. Considering the complex spatial distribution characteristics of microseismic events, an improved density clustering algorithm based on dynamic adjustment of the search range of the microseismic source radius was proposed to divide the microseismic activities into several clusters with high internal correlation. On this basis, the natural neighbor interpolation method was adopted to establish the inversion method of "microseismic signal apparent stress → microseismic event apparent stress → microseismic cluster apparent stress → mining-induced stress field". Engineering practice in deep metal mines shows that the apparent stress concentration areas obtained by this method are highly consistent with the actual areas where ground pressure disasters occur, which can provide strong theoretical and technical support for the identification of potential dangerous areas and risk control of mining-induced ground pressure in deep metal mines.
- 1
-
Experimental study on reinforcement of uranium tailings with sodium silicate and Bacillus pasteurelli
Abstract:
This study selected a specific uranium tailings sample as the research subject to investigate the synergistic mechanism between sodium silicate and Bacillus bassii in enhancing the stability of uranium tailings. The OD value and pH value of Bacillus pasteurii in the environment containing sodium silicate were measured to analyze the influence of different modulus and mass fraction of sodium silicate solution on the growth law of Bacillus pasteurii. Based on the microbial-induced calcium carbonate precipitation (MICP) technology, the sodium silicate and Bacillus pasteurii injection reinforcement test was carried out on the uranium tailings column, and the unconfined uniaxial compressive strength of the uranium tailings column in different test groups was compared and analyzed. The results show that the appropriate mass fraction and modulus of sodium silicate can significantly improve the unconfined compressive strength of the uranium tailings column. Among them, the unconfined compressive strength of the tailings column corresponding to the sodium silicate solution with a modulus of 2.3 and a mass fraction of 5% is 283.4 Pa, which is 11.4% higher than that of the uranium tailings column reinforced by Bacillus pasteurii alone (255.1 Pa). X-ray diffraction (XRD) detection shows that the precipitates generated in all test groups are mainly composed of calcium carbonate crystals, and the proportion of calcite crystals generated is higher than that of the control group reinforced by Bacillus pasteurii alone, and the thermodynamic stability of the crystals is better. Scanning electron microscopy (SEM) images combined with energy dispersive spectroscopy (EDS) analysis show that the test groups with added sodium silicate solution generate more calcium carbonate crystals than the control group reinforced by Bacillus pasteurii alone, and the surface is smoother and flatter, and the structure is more compact. This achievement provides theoretical guidance for improving the reinforcement technology of uranium tailings ponds
- 1
-
Global Trend of Hot Dry Rock Research Based on Bibliometric Analysis
Abstract:
Research on the exploration and development of hot dry rock (HDR) is significant for promoting the global energy transition, achieving sustainable utilization of clean energy, and supporting carbon neutrality goals. To comprehensively understand the latest research progress and technological trends in the HDR field, a bibliometric analysis and thematic exploration of relevant papers and patents were conducted. The analysis covered multiple dimensions, including publication trends, patent application trends, distribution of major countries and institutions, research themes, and hotspots. Results indicate that HDR research is in a period of rapid global development, with China leading in basic research and technological innovation, though there is room for improvement in research quality and internationalization. Research hotspots focus on five key areas: geothermal energy extraction and utilization, HDR genesis and resource exploration, reservoir mechanical properties and heat storage construction, reservoir monitoring and evaluation, and seismic prediction and control. Important emerging research directions include high-temperature and stress coupling mechanisms, low-temperature fracturing technology development, and the application of nuclear magnetic resonance technology. While HDR development is transitioning into the engineering demonstration phase, commercialization still faces challenges such as technical bottlenecks, environmental risks, and insufficient economic viability. Future efforts should focus on advancing geophysical exploration technologies, enhancing heat reservoir modification techniques, optimizing hydraulic fracturing and drilling processes, investigating the dynamic evolution of fracture networks and long-term stability of heat reservoirs, and improving heat extraction and heat exchange efficiency. Additionally, strengthening the integration of fundamental research and applied technologies is critical to overcoming technical challenges, reducing development costs, and promoting the sustainable utilization of HDR resources.
- 1
-
Optimization study on the Recovery Scheme of the top pillar resources under the overlying graded tailings filling body
Abstract:
The recovery of the top pillar under the graded tailings filling body on the Liutangfang iron mine in Anhui Province is facing safety issues. The initial mining plan was determined through theoretical analysis, and the stability was analyzed through numerical simulation to ultimately optimize the structural parameters of the mining site. Firstly, it is believed that the maximum safe thickness that can be mined is 5.1m, through the calculation of the thickness to span ratio method, load transfer line intersection method, and Proctor arch method. Then, the relationship between the width and length of the drift was calculated using the Mathews stability method, and the structural parameters of the mining site were preliminarily selected. Finally, it was found that the roof settlement, tensile stress, and plastic zone of transverse drift were lower the along-vein drift, and the mining impoverishment rate was also lower. Therefore, the optimal mining plan is a combination of through vein excavation and deep hole blasting. The parameters for drift are: tunnel length of 30m, height of 6m, and width of 6m.
- 1
-
Study on mechanical properties and damage mechanism of backfill under the alternating action of dry and wet cycling and sulfate attack
Abstract:
Aiming at the erosion damage of backfill materials in non-ferrous metal mines under dry and wet cycling and sulphate environment, dry and wet cycling tests of backfill samples were carried out in tap water, 3%, 6% and 9% sodium sulphate solution. The evolution of backfill microstructure and corrosion damage mechanism at different alternating action periods were studied by scanning electron microscopy. During 120 cycles of wetting and drying, the mass of the filling body decreased by only 0.19% under tap water exposure. However, under the erosion of 3%, 6%, and 9% sodium sulfate solutions, it increased by 0.73%, 1.52%, and 3.64% respectively. The magnitude of mass decrease increased gradually with the concentration of the solution. Under the condition of the same sodium sulfate solution concentration, the uniaxial compressive strength of the backfill specimen gradually decreases with the increase of the times of alternating action. After undergoing 30 cycles of erosion in a 3% sodium sulfate solution involving both wet and dry conditions, the uniaxial compressive strength of the backfilling increased from 14.36 MPa to 14.85 MPa. The free sulfate ions in the sodium sulfate solution enter the backfill and chemically react to form ettringite. A small amount of ettringite is filled into the internal pores of the backfill, which enhances the physical properties of the backfill to a certain extent. However, with the increase of ettringite, the density of microscopic defects in the filling body increases, resulting in a gradual decline in its strength.
- 1
-
Study on the thickness of isolated pillar in caving-to-backfilling mining
Abstract:
In order to ensure the orderly connection from caving mining to backfilling mining in underground mines, it is necessary to leave a certain thickness of isolated pillar. The thickness of isolated pillar is preliminarily determined by theoretical calculation, and the three-dimensional fine ore body mining model is established by numerical simulation, and the stability of the stope in the whole process of mining under different thickness of isolated pillar is analyzed, and the three-dimensional numerical model is established by means of numerical simulation. The stope stability in the whole process of mining under different thickness of isolation pillar is analyzed, and the optimal safe thickness of isolation layer is determined. The results show that the thickness of vertical isolation pillar and horizontal isolation pillar calculated by Bieniawski expression and K.B.Rupeneyt theory is 9.0 m and 9.36 m, respectively. The distribution of displacement, maximum principal stress, minimum principal stress, plastic failure zone and safety factor under different vertical isolation pillar thicknesses were analyzed by FLAC 3D. Finally, the optimal thickness of vertical isolated pillars was determined to be 10 m. The isolated pillar can effectively reduce the interaction between the caving mining and filling mining areas, and provide a scientific basis for the safe mining of deep mineral resources.
- 1
-
Study on Stability Evaluation and Numerical Simulation of Open-Pit Copper-Cobalt Mine Slopes
Abstract:
Aiming at the slope stability challenges of open pit of Kisanfu Copper-Cobalt Mine (KFM), a globally significant strategic mineral resource base, the slope instability mechanism was studied by multi-method integration and an optimized evaluation model was established to ensure the safe mining and economic benefits of the mine. Based on the engineering geological characteristics of the mining area, the structural development, rock mass strength characteristics and hydrological conditions are systematically studied, and the theoretical correlation model linking rock compressive strength with rock mass strength parameters is constructed. Then the failure mechanisms of open-pit mine slope is analyzed, and the calculation method for the most dangerous composite slip surface is optimized by the limit equilibrium method of slope stability. Finally, ttwo typical geological sections are selected as case studies, the deformation and failure process of stope slopes is analyzed by numerical simulation technology. The results show that: (1) tectonic activity significantly influences slope failure modes, which are mainly characterized by three failure modes: "siting-slip", "arc" and "wedge". (2) The numerical simulation reveals that the upper part of the stope slope experiences predominant settlement deformation (69.9 mm and 36.3 mm), the localized horizontal deformation occurs in the face area, and the slope toe area shows strain concentration phenomenon. (3) The stability coefficient of the stope slope, obtained through both the limit equilibrium method and numerical simulation analysis is between 1.400 and 2.278, which meets the safety reserve requirement of slope 1.20. The research results provide a scientific basis for slope design and disaster prevention at the KFM Copper-Cobalt Mine, and ensure the safety production demand of mine. The multi-method evaluation system offers a technical reference for slope stability assessment in open-pit mines.
- 1
-
Borehole Structural Plane Segmentation and Parameter Visualization Method with Dual-Encoder Attention Network
Abstract:
Although borehole camera technology is widely used for roadway surrounding rock quality assessment, its structural plane recognition suffers from inefficiency, subjectivity and low accuracy. To address challenges including uneven illumination, complex background and morphological variations in borehole images, a Dual-Encoder Interactive Attention Enhancement Fusion Network (DISA-FuseNet) is proposed. The network adopts UNet's encoder-decoder architecture, employing dual encoders with Swin Transformer and ResNet50 to simultaneously capture global contextual information and local detail features. The concatenated feature maps are processed by a Statistical Aggregation Channel Attention (SACA) module for attention weighting, suppressing rock background noise and irrelevant information. The low-level features are then fed into an Adaptive Hierarchy Enhancement (AHE) module after concatenation to enhance multi-scale structural plane feature extraction. Experimental validation on a self-built borehole structural plane dataset demonstrates that DISA-FuseNet outperforms five benchmark models (UNet, Deeplabv3+, Trans-UNet, DeepCrack and CrackFormer) in mean Intersection over Union, mean Pixel Accuracy, Recall, Precision and F1 scores, achieving improvements by 8.44, 9.51, 8.52, 10.6 and 9.62 percentage points respectively compared to the baseline UNet model. A structural plane parameter extraction and 3D visualization method is further proposed, enabling precise acquisition of key parameters and construction of interactive 3D visualization models. Practical engineering case studies confirm the method's effectiveness and engineering applicability.
- 1
-
Research on source identification and migration law of slag-type debris flow based on deep learning
Abstract:
Slag-type debris flow is an artificial debris flow caused by the irrationality of mineral resource exploitation in mountainous areas and the random stacking of slag under heavy rainfall conditions. Therefore, it is of great significance to understand its formation mechanism and movement law. UAV oblique photography technology was used to obtain images, the provenance conditions in the study area were analyzed, the YOLOv5s improved model was used to realize the identification of provenance targets, and the PFC3D particle flow software was used to numerically simulate the starting state of the debris flow source. The results show that the UAV oblique photogrammetry technology has the advantages of high resolution, low cost and flexible operation, and in view of the limitations of the current debris flow source detection algorithm, the YOLOv5s-GCE model is proposed, which shows excellent performance in debris flow source detection. The numerical simulation method of particle flow was used to study the migration law of debris flow, and through PFC3D numerical simulation, it was found that the migration of debris flow has a certain regularity, which is of great significance for geologists to solve the protection of slag debris flow.
- 1
-
Creep Characteristics and Constitutive Model of Strong-weak Combined Composite Filling Structure
Abstract:
The two-step filling mining process forms a strong-weak composite filling structure that jointly bears the roof load. The long-term stability of the backfilled stope is influenced by its overall creep characteristics. Nine groups of composite filling specimens with different strong-weak combinations were prepared, and uniaxial graded loading creep tests were conducted to analyze the effects of various combinations of strong and weak media on their creep behavior. Considering the time-dependent degradation of mechanical properties and the characteristics of the accelerated creep stage, an improved Nishihara model was developed to characterize the creep behavior of the composite filling structure. The study shows that the strong medium has a more significant impact on the overall creep characteristics of the composite specimens. As the strength of the strong medium increases from 23.60 MPa to 33.80 MPa, the elastic modulus increases from 1.85 GPa to 2.18 GPa, and the axial creep increments under the first three stress levels decrease by 59.7%, 57.4%, and 68.9%, respectively. The instantaneous creep rates decrease by 31.55%, 21.46%, and 23.14%, respectively. The transverse strain difference between the strong and weak media increases from 260 με, 368 με, and 524 με to 685 με, 895 με, and 1032 με, respectively. Higher stress levels result in greater strain differences, and the overall creep failure mode of the specimens transitions from shear failure to compressive splitting failure. The improved Nishihara model achieves a fitting accuracy exceeding 0.93 for the experimental data, effectively simulating the entire creep process of the composite filling structure.
- 1
-
Experimental and Numerical Simulation Research of Directional Gas Fracturing based on Radial Guide Groove Technology
Abstract:
Among the rock mass weakening methods, gas fracturing can produce more complex fracture network effect than hydraulic fracturing. In order to study the fracture propagation mechanism of gas fracturing in the field of directional fracturing technology, laboratory experiment and numerical simulation of directional gas fracturing based on guide groove technology were carried out. a preparation method of guide groove is proposed in the experiment, and a special sealing fixture is designed to simulate the principle of packer. The process of gas fracturing was monitored by means of acoustic emission device. The experimental results show that the radial guide groove can obviously change the propagation direction of gas fracturing fractures within a certain scale, and the fracture initiation pressure is reduced by about 30% compared with that without guide groove. Under the dynamic loading method of gas fracturing, a unique fracture network of primary fracture and secondary micro-fracture appears, and the fracture width increases by 2-3 times compared with the quasi-static loading method. On this basis, LS-DYNA is used to simulate the dynamic dynamics of transient gas fracturing with or without guide groove to verify the experimental phenomenon. This conclusion can promote the deep hard rock directional fracturing technology and rock mass weakening method, and provide technical support for the implementation of directional gas fracturing technology.
- 1
-
Thickness optimization and stability analysis of aquifer strata mined under water-rich karst aquifer
Abstract:
Astract:In order to solve the problem of water inrush and instability of stope caused by a large amount of fissure water in the water-rich fault fracture zone, this paper takes the northern stope of Zhongguan Iron Mine as the background, carries out water pressure monitoring test, uses FLAC 3D to explore the sensitivity of stope stability to water pressure change, and finds a water pressure gradient with obvious changes. Then, a numerical model of "water pressure-water barrier thickness" is established to explore the control effect of different water pressure values and water barrier thickness on stope stability. The stability and variation rules are analyzed with the distribution of roof stress, displacement and plastic zone as indicators, and the corresponding relationship between water pressure and water barrier thickness is obtained. The results show that the north ore body of Zhongguan Iron Mine is a typical large water deposit, and the water pressure is between 0.1 and 2.0MPa. When the water pressure is greater than 1.0MPa, the influence of water pressure on the roof stability is significant. If the water pressure is 0.1MPa, the thickness of the waterproof layer should not be less than 1.8m. When the water pressure is 0.5MPa, the thickness of the waterproof layer should not be less than 3m; When the water pressure is 1.0MPa, the thickness of the waterproof layer should not be less than 4m; When the water pressure is 1.5MPa, the thickness of the waterproof layer should not be less than 5.6m. When the water pressure is 2.0MPa, the thickness of the waterproof layer must be no less than 7.1m. The simulation results provide theoretical support for determining the thickness of the water barrier layer with different water pressure values.
- 1
-
Research on Feature Extraction and Application of LiDAR Data in Mine Landslide Treatment Areas
Abstract:
Landslides are highly destructive natural disasters, and accurately assessing the ecological restoration effects in mining landslide treatment areas is of great significance for ensuring surrounding safety and ecological stability. In this study, airborne LiDAR data were used to construct Digital Elevation Models, Digital Surface Models, and Normalized Digital Surface Models for terrain feature extraction. Combined with Visible Difference Vegetation Index and texture information features, the Pianqiaogou landslide treatment area in Taiyuan's Du'erping Coal Mine was selected as the study area to perform ground object information extraction and classification using Support Vector Machine optimized by Particle Swarm Optimization algorithm. The results demonstrate that the proposed method achieves satisfactory classification performance, with the treatment area's Shannon diversity index reaching 0.96, verifying the effectiveness of mining landslide treatment measures. This study provides valuable insights for the application of LiDAR technology in mining landslide treatment areas.
- 1
-
Comparative study on vibration thickening mechanism and dynamic thickening test of tail mortar
Abstract:
In order to reveal the synergic effect of vibration on density and sand discharge, the vibration density mechanism of tail mortar was discussed. Based on the independent vibration density test system, the discontinuous density and sand discharge tests under vibration were carried out, which verified the feasibility of vibration effect on improving the density efficiency of tailings slurry and the activation of bottom flow sand discharge. The theoretical analysis shows that the key to increase the underflow concentration is to make the tailing particles accumulate in cone structure in dense body. The eccentric vibration mechanism conducts energy in sinusoidal harmonic motion, and the excitation range of vibration rod is related to the quality of slurry bulk weight vibrator. The activated region of the cylinder is formed around the vibrating rod during vibration and is negatively correlated with the yield stress and plastic viscosity. Based on the contrast experiment of flocculation density with vibration, without vibration and with vibration. The test results show that the vibration can increase the underflow concentration by 7.03%~8.2%, which has a remarkable effect. With the increase of feed rate, the content of overflow water and solid increases first and then decreases, and increases by 7.14%~12.4% under the action of vibration. Under the condition of no vibration, the underflow concentration increases with the increase of feeding speed, but the overflow water solid content does not increase significantly. The research results provide a basis for the development of high efficiency thickening equipment.
- 1
-
Research on Grey VIKOR Model for Evaluating Emergency Rescue System of Metal Mines Based on Combination WeightingZhu Min, Wang Yajun, Gong Yongchao, Wang Xu
Abstract:
To scientifically and reasonably evaluate the level of emergency rescue system construction, 26 indicator factors were selected from four dimensions: pre emergency prevention, pre emergency preparation, in-process emergency rescue, and post recovery and reconstruction. The interval analytic hierarchy process improved CRITIC method was used to calculate the weights of each indicator factor, and the grey correlation method was used to improve the traditional VIKOR method. A multi criteria compromise decision-making model for metal mine emergency rescue system based on combination weighting grey VIKOR was proposed. Taking five underground metal mines in Hunan Province as the research background, the established model was applied to evaluate the emergency rescue system. The evaluation results were compared with the weighted grey correlation method and weighted TOPSIS method, and the differentiation analysis of emergency rescue system construction was carried out based on the radar chart method. The results show that the evaluation results of the model are reasonable and reliable, with stronger applicability and higher identification, verifying the feasibility of the combination weighting grey VIKOR model in the evaluation of emergency rescue systems in metal mines.
- 1
-
Optimization of Industrial Culture Medium Ratio in Microbial Mineralization Based on Response Surface MethodologyZHANG Zhijun1,2,LIU Bingzheng1,2,ZHENG Huaimiao2,3,TIAN Yakun1,2,HU Lin1,2,WU Lingling1,2
Abstract:
In order to reduce the cost of microbial induced calcium carbonate precipitation (MICP), the effects of industrial grade bovine bone peptone content, soy peptone content, sodium chloride content, and urea content on the microbial quantity and urease activity of Bacillus subtilis cultured for 16 hours were studied.SUsing response surface methodology to optimize the optimal ratio of industrial culture medium.SAnd detect the microbial quantity and urease activity of the bacterial solution under the optimal ratio, and bond it with different concentrations of cementing solution separately from the analytical pure culture medium to detect the production of calcium carbonate and SEM.SThe results showed that the optimal ratio was 25 g/L bovine bone peptone, 7.5 g/L soy peptone, 5 g/L industrial sodium chloride, 22.2 g/L industrial urea, and 1000 mL pure water.SThe microbial count of Bacillus subtilis liquid cultured for 16 hours under this ratio was 1.672 cell/mL, and the urease activity was 0.037 ms/min, both of which were within the prediction error, indicating feasibility of the results.SThe content of calcium carbonate generated by cementation is not significantly different from that of analytical pure culture medium, and the cementation effect is stronger than that of analytical pure culture medium.SThe research results can provide a low-cost medium ratio scheme for the large-scale engineering application of MICP.
- 1
-
Study on pre-splitting blasting parameters of a small dip open-pit slope in Yunnan
Abstract:
At present, the pre-splitting blasting method is not used to carry out the construction of the side slope in an open pit in Yunnan, and the slope forming effect is poor. In order to improve the forming quality and design coincidence rate of the small dip angle side slope in the stope, the pre-splitting blasting test is carried out for the 55° gentle slope. In this paper, the control variable method is used to study the field control test with the pre-splitting hole spacing, line charge density and hole diameter as variables. The test results show that it is feasible to use pre-splitting blasting method to realize slope forming in the 55° small inclined slope in the blasting area, and the quality of the slope after blasting is significantly improved, and the design coincidence rate is high. Under the conditions of hole spacing of 1.3 m, hole diameter of 115 mm and linear charge density of 0.8 kg/m, the best blasting effect was obtained in the test area, and the hole retention rate was about 80 %.
- 1
-
Study on dynamic response analysis method and numerical example of goaf group structure under blasting stress disturbance
Abstract:
In order to study the dynamic response and stability of the mining airspace group under the disturbance of blasting stress, the structural characteristics of the mining airspace group and its interaction with the surrounding rock are synthesized, the dynamic response model of the mining airspace group is constructed, the structural dynamic response analysis method is created, the structural dynamic instability criterion is put forward, and the stability is judged, and the computational analysis is carried out by taking a certain underground limestone mine as an object, and it is validated in comparison with the results of numerical simulation and on-site monitoring and the influence of different blasting frequency, roof span-height ratio and pillar height-width ratio on it is studied. Different blasting frequencies, roof span-to-height ratios and pillar height-to-width ratios affect the stability of the structure. The results show that: under the disturbance of blasting stress, the calculation results of the dynamic response analysis method tend to be consistent with the numerical simulation and on-site monitoring results; the velocity and displacement response of the air pocket group are mainly concentrated in the x and y directions; the blasting frequency significantly affects the velocity and displacement response of the air pocket group, and the two types of peaks are characterized by a “single-peak” curve in relation to the frequency; The peak velocity increases and then decreases with the increase of roof height ratio, and the inflection points of the peak velocity curves in x and y directions are 0.8 and 0.6 respectively; the peak displacement increases linearly with the increase of roof height ratio, and the slopes of the linear changes in x and y directions are 0.926 and 0.670 respectively; the peak velocities and displacements increase with the increase of the column height-to-width ratio with the negative exponential growth, which has a weak influence on the stability of the mine hollow zone group. The research results provide a new method for the structural dynamic response of the mining airspace group.
- 1
-
Research on the Method of Mining from Collapse to Filling in a Certain Iron Mine and Optimization of Mining Site Structural Parameters
Abstract:
A certain iron mine has been using the bottomless pillar segmented collapse method for mining since its inception. Due to severe surface subsidence and large impoverishment losses, the mine plans to use the filling method for deep ore body mining. Based on the stability of the ore rock, three filling mining schemes are proposed for areas with poor surrounding rock, namely the segmented filling mining method with pre controlled roof protection, the filling mining method with pre controlled roof upward step access, and the combined mining method of downward access and upward middle deep hole. After comprehensive comparison of the technical and economic indicators of different schemes and the advantages and disadvantages of each scheme, the filling method is finally adopted for mining. According to the mining scheme, the segmented height is optimized by numerical simulation under certain conditions of the middle section height and the span of the mining site. The production capacity demand was optimized and analyzed to obtain a segmented height of 20m. When using this method in mining applications, comprehensive analysis has brought about a benefit of about 7.7 million yuan to the mining economy, which can provide reference for similar mines.
- 1
-
Study on Inter-Provincial Network Characteristics and Collaborative Development of "Safe Carbon Reduction" Efficiency in China's Mining Industry
Abstract:
To explore the status of "safe carbon reduction" in China"s mining industry, this study employs the Data Envelopment Analysis (DEA) method to measure the efficiency of "safe carbon reduction" in the mining industry across 30 provincial-level regions in China from 2014 to 2022. Additionally, Social Network Analysis (SNA) is utilized to examine the spatial association network characteristics in detail. The results reveal that the overall efficiency of "safe carbon reduction" in China"s mining industry exhibits a growth trend with relatively small regional disparities, indicating a shift towards balanced and coordinated development in the green transformation of mining. In terms of the spatial association network, while there are some interactions among provincial regions, the overall connectivity is weak, and interaction frequency needs improvement. Further analysis shows that different regions play distinct roles in spatial spillover effects. Certain provinces occupy key positions in the network, demonstrating high centrality and significant roles as structural holes and intermediaries. Moreover, while intra-regional connections are relatively strong, the collaborative effects between regions still have room for enhancement. This study provides a novel perspective for comprehensively understanding the status of "safe carbon reduction" in China"s mining industry and offers scientific guidance for optimizing policy design and promoting regional collaborative development.
- 1
-
Fig.1 Distribution map of soil sample points
Abstract:
this paper takes the single pollution source ( open-pit stope, dump and tailings reservoir ) and multi-pollution source ( three common pollution areas ) in the mining area of Qidashan Iron Mine as the research object, and systematically analyzes the spatial distribution characteristics. Based on the analysis of the concentration of heavy metals in the soil near the above four pollution sources, the spatial distribution characteristics of heavy metal pollution in the soil of the open-pit iron mine were analyzed. The results showed that the spatial distribution characteristics of the four types of heavy metal pollutants were affected by the types of pollution sources and the physical and chemical properties of the soil. The closer the single pollution source was to the pollution source, the higher the content of heavy metals was, while the multi-pollution sources showed the characteristics of high concentration of heavy metals in the middle area under the interaction. Under the influence of rainwater leaching and deep soil solidification, heavy metals in the soil show the distribution characteristics of low surface layer, high middle layer and low deep layer.
- 1
-
Research and Application of a Reasonable Determination Method for the Rock Movement Angle of Steeply Dipping Multiple Ore Veins
Abstract:
Aiming at the limitations of traditional methods for determining the rock movement angle under the geological conditions of steeply inclined multiple ore veins, a comprehensive analysis method based on the critical granular column theory and numerical simulation is proposed. Taking the Fandeco Mining Area in Henan Province as the research object, through engineering analogy, theoretical analysis and numerical simulation, the influence law of the mining of steeply inclined multiple ore veins on the rock movement angle is deeply studied. The research reveals the nonlinear relationship between the rock movement angle and the distance, quantity and dip angle of the ore veins, and corresponding empirical formulas are established. The results show that the range of the rock movement angle in the mining area is from 69° to 78°, and the proportion of the height of the critical granular column ranges from 15.8% to 20.7%. By combining the height of the critical granular column with the dynamic correction model of the rock movement angle, the delineation scheme of the safety pillar is optimized, increasing the resource utilization rate to 82.3%. Based on the theoretical calculation and the results of engineering practice, a dynamic correction model of the rock movement angle under the coupled action of multiple ore veins is proposed, breaking through the applicable boundary of the traditional analog method for single ore veins, and providing a strong basis for the safe mining of similar complex steeply inclined multiple ore veins.
- 1
-
Research on the Evaluation Method of Ecological Restoration Effect in Open-pit Mining Areas Based on Multi-source Data
Abstract:
Regarding the evaluation methods for the ecological restoration effectiveness in open - pit mining areas, based on multi - source data such as remote sensing, precipitation, and soil, a comprehensive ecological restoration effectiveness evaluation index system composed of five aspects, namely vegetation coverage, soil moisture, soil and water conservation, air quality, and landscape ecological risk, was proposed and constructed from both macro and micro levels. Taking the Quzhai cement mining area in Luquan, Shijiazhuang as the experimental area, the results show that the overall ecological restoration effect in the mining area is relatively significant. In particular, the proportion of areas with good and better restoration increased from 47.85% in 2021 to 60.43% in 2023. However, the areas with poor and very poor restoration also expanded, rising from 6.60% to 11.29% and from 0.29% to 2.77% respectively. This indicates that more precise and effective ecological management measures need to be implemented for some specific areas in the mining area, and attention should be paid to the risks arising from the transfer of landscape types. The research results can provide a reference for scientific decision - making in ecological restoration in mining areas.
- 1
-
Development and application of intelligent drilling machine for mining stress relief
Abstract:
With the increase in the mining depth of mines with high in-situ stress, the key borehole pressure relief method for rock burst prevention is faced with the problem of insufficient intelligence of traditional drilling rigs. To this end, an innova-tive design scheme for an intelligent mine pressure relief drilling rig is proposed. This intelligent drilling rig integrates four key components: the chassis walking unit, the drilling execution unit, the support lifting unit, and the drill rod magazine unit. Among them, the unique automatic drill rod changing device can drive the drill rod to move flexibly within the precise track system constructed by the horizontal pushing device and the vertical pushing device. With the cooperation of the fixing groove and the clamping mechanism, the automatic drill rod changing operation process can be completed efficiently and accurately, significantly improving the automation level and continuity of the operation. At the same time, the advanced in-drill information monitoring and analysis system built into the drilling rig can capture and analyze multi-source data during the drilling process in real time, laying a solid foundation for precisely adjusting the drilling parameters and promptly warning of potential risks. Firstly, the overall structure of the intelligent drilling rig, as well as the structural characteristics and internal relationships of each unit, will be introduced in detail to deeply reveal its working principle. Subsequently, based on the in-depth analysis of a large amount of vibration signal data and related vibration information, the excellent performance of the intelligent pressure relief drilling rig will be comprehensively verified. The research results show that, compared with traditional drilling rigs, the intelligent drilling rig greatly reduces the risk of personnel exposure and equipment failure in terms of safety, and significantly shortens the drilling time and auxiliary operation time in terms of construction efficiency, achieving a substantial improvement in comprehensive per-formance. The research may play an important role in promoting the safe production and efficient operation of rock burst prevention.
- 1
-
Prediction method for surface subsidence in underground mining based on LSTM-DCNN and transfer learning
Abstract:
During the mining process of underground ore bodies, the collapse of goaf can disrupt the stress balance of rock layers, leading to geological disasters and endangering surface facilities. In order to improve the accuracy of surface subsidence prediction in mines without actual monitoring data during the unmined stage, ensure personnel safety and mining production, a method combining neural networks and transfer learning for underground mining surface subsidence prediction is proposed. The method combines the advantages of long short-term memory (LSTM) networks to accurately extract time series features and deep convolutional neural networks (DCNN) to extract local features of data, thereby improving the accuracy of the prediction model. Based on the mining design of Zhonggangou vanadium titanium magnetite, a prediction model was used to predict surface subsidence under different mining schedules. The results showed that the proposed model exhibited high accuracy in predicting surface subsidence under different mining schedules. This method can provide new ideas for predicting surface deformation in similar mines and support mine safety monitoring.
- 1
-
Improved Dynamic Programming with Ant Colony Optimization for Efficient Mining and Stripping in Large-Scale Open-Pit Mines
Abstract:
In order to improve the efficiency and accuracy of mining and stripping planning for large-scale open-pit mines, this paper proposes an improved dynamic programming method by introducing the Ant Colony Optimization (ACO) algorithm to optimize the incremental volume dynamic sequencing process. Traditional dynamic programming methods face issues such as high computational complexity and mismatched solution quality with practical requirements when dealing with large-scale mines. This study integrates the distributed search mechanism of the ACO algorithm and reconstructs the state transition path selection strategy, significantly reducing computational complexity. The method was validated through its application in a real open-pit quarry in Guangdong, demonstrating its significant impact on improving the efficiency of mining and stripping plans, optimizing resource allocation, and enhancing economic benefits. The results show that the improved algorithm reduced computation time from 50 hours to 6.45 minutes, optimized the stripping ratio from 0.39 to 0.124, while maintaining high optimization accuracy. The results indicate that the proposed method offers significant advantages in enhancing solution efficiency and economic benefits, providing a new approach for intelligent mining planning.
- 1
-
Study on Thermal-Alkali Activation of Copper Tailings for the Preparation of Single- Precursor Geopolymers
Abstract:
The comprehensive utilization of tailings is one of the key aspects of green development in the mining industry, and the preparation of tailings into geopolymers holds significant promise. Due to the low reactivity of tailings, thermal-alkali activation can effectively enhance their reactivity, thereby optimizing the performance of geopolymers. To analyze the phase and chemical bond changes during the activation process, exploring the activation mechanism, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) was employed. The results indicate that the 7-day compressive strength of thermally-alkali-activated tailing geopolymers can reach up to 15.59 MPa, representing a more than tenfold increase compared to non-activated samples. The strength of the geopolymers improved with increasing alkali content, calcination temperature, and duration. During the thermal-alkali activation process, muscovite in the tailings underwent structural distortion through group substitution, transforming into an amorphous phase. The alkali content and calcination temperature had a notable impact on the activation effect. The study provides a theoretical foundation for the selection and activation of tailings in geopolymer preparation.
- 1
-
Cumulative Damage Effect And Support Of Surrounding Rock Under Cyclic Blasting Excavation Of High-stress Roadway
Abstract:
In view of the deformation of surrounding rock in deep roadways, blasting damage to surrounding rock is regarded as one of the key factors inducing roadway instability. In this study, based on the roadway with a buried depth of more than 800 m in Jinfeng Gold Mine, a numerical model of full-face blasting was established by ANSYS/LS-DYNA for five full-face blasting, and four typical positions were selected to analyze the cumulative damage effect of repeated blasting on surrounding rock. Based on the observed cumulative damage evolution, a new support strategy—comprising rock grouting, extended anchor mesh, and shotcrete—was proposed and implemented on-site. In a single full-face blasting, the first two sections of blasting vibration will induce the expansion of the surrounding rock damage zone, resulting in the acceleration of the surrounding rock displacement and damage during the latter two sections of blasting. In multiple full-face blastings, the existing damage zone will invade the range of rock mass excavated by subsequent blasting, forming a new and old damage zone and accelerating the expansion. The range of the new damage zone is about 20% larger than that of the previous one. After optimizing the support scheme, the displacement of roadway roof and two sides decreased by 41.37% and 42.03%, respectively. The pull-out test of the bolt shows that the displacement of the new bolt is 37.2% less than that of the original bolt, and the Z value of the rebound coefficient is significantly improved. This study provides valuable insights into the optimization of blasting and support strategies for deep, high-stress roadway excavation.
- 1
-
Research on the efficient recovery scheme of the top and bottom pillar resources under the overlying backfill of Xitieshan lead-zinc mine
Abstract:
After years of mining in Xitieshan Lead-Zinc Mine, a large amount of pillar resources have been left. Due to the high grade of the ore body, the recovery of the top and bottom pillar resources is imperative. Through on-site sampling and strength testing of the filling body above the bottom pillar, it is found that the strength of the filling body is much lower than that of the indoor test. Therefore, it is necessary to set up certain roof-protecting pillars. Combining the test results, three feasible mining schemes are proposed: the combined mining method of sublevel open stoping with subsequent filling and upward drift, the false roof + sublevel open stoping with subsequent filling mining method, and the pre-controlled roof + downward medium-deep hole sublevel open stoping with subsequent filling mining method. A comprehensive analysis of the advantages and disadvantages as well as the technical and economic indicators of the three schemes is carried out, and finally the combined mining method of sublevel open stoping with subsequent filling and upward drift is determined to be adopted. The mining steps and sequence of the medium-deep hole stope are determined by means of numerical simulation. In the process of mining the drift stope, an innovative scheme of retreating and extracting some pillars is proposed, and the extraction amount distribution of different roof-protecting pillars is determined by numerical simulation, which improves the recovery rate of the pillars.
- 1
-
Table 1 Spectral index and its calculation formula
Abstract:
The excessive development of mineral resources has intensified the pressure on the ecological environment of mining areas. As a solid waste containing heavy metals, the storage of tailings has become a key issue in ecological restoration by damaging soil organic matter (SOM). This study is based on hyperspectral remote sensing technology to establish a tailings SOM monitoring system. A mining area in Hebei Province is taken as the research area, and vegetation canopy hyperspectral data is obtained through ASD surface spectrometer and GF-5 satellite. Tailings samples are collected for physical and chemical property analysis. The Boruta algorithm is used to screen sensitive bands, and four models including multiple stepwise linear regression (SMLR), partial least squares regression (PLSR), random forest (RF), and extreme gradient boosting (XGBoost) are constructed for accuracy verification. The results showed that the RF model had the best performance for ground ASD spectral data (R 2=0.92, RMSE=0.37), which is suitable for fine monitoring; The XGBoost model performs the best on GF-5 satellite data (R 2=0.73, RMSE=0.53), meeting the needs of large-scale rapid evaluation. Research has confirmed that through the synergistic optimization of spectral mathematical transformation and linear and nonlinear models, ground air multi-scale SOM monitoring can be achieved, which significantly improves the efficiency compared to traditional detection methods. The research results can provide scientific basis for ecological restoration in mining areas, promote environmental management and sustainable development of mining.
- 1
-
Instability Characteristics of Open-pit Bottom Pillar System based on the Gravity Increase Method
Abstract:
Open stope mining with subsequent filling method is adopted in the transition from open-pit to underground mining project in Sijiying Iron Mine, and horizontal isolation pillars are needed to realize the isolation of open-pit and underground mining system to ensure the safety of underground mining. In order to improve the overall stability of the mining area, the effects of gravity acceleration on the evolution characteristics of stress field, the rule of displacement field distribution and plastic zone expansion of the pit bottom pillar system were studied, by using the gravity increase method, with the pit bottom boundary pillar’s thickness of 45m and the panel pillar width of 20m. The results show that: (1) under the initial gravity acceleration, the pit bottom pillar system is basically in a stable state; (2) with the increase of the gravity acceleration, the stress concentration phenomenon of the pillar system continues to strengthen. When the gravity acceleration increases to 2 times of the initial one, the maximum value of the concentrated stress reaches 56.9MPa. The compressive stress value of the pit bottom boundary pillar is greater than that of the panel pillar. The distribution range of the tensile stress also expands gradually with the increase of gravity acceleration, and finally reaches the tensile strength of rock mass. (3) Under the initial gravity acceleration, the maximum displacement of the pit bottom pillar system is 258mm and the distribution range is very small and the pit bottom pillar system is in a stable state. However, the displacement increases exponentially with the gravity acceleration. The range between N22 to N26 exploration lines in the mining area is the most dangerous area, which may lead to the "domino effect" of the pillar system instability failure at the bottom of the open pit, resulting in multi-pillar compound instability failure. (4) it is suggested that, in the process of mine design and mining, measures should be taken to improve the bearing capacity of the panel pillars and the filling quality of the mining goaf in the range of N22 to N26 exploration lines if the mine to ensure the stability of the pit bottom pillar system.
- 1
-
Study on Compressive Mechanical Properties and Crushing Law of Phosphate Rock under Different Saturation Time
Abstract:
In order to study the influence of saturation time on the mechanical properties and crushing law of phosphate rock, static and dynamic mechanical tests under different strain rates were carried out on phosphate rock samples of natural, saturated 48 h and saturated three months. The results show that under the condition of low strain rate loading such as static load, the strength of phosphate rock decreases with the increase of saturation time, but the strength reduction rate shows a trend of fast first ( before 48 h ) and then slow. The compressive strength of saturated 3 months is 9.4 % lower than that of saturated 48 h. Under the medium and high strain rates ( 43 ~ 146s-1 ) such as dynamic load, the strength of phosphate rock is affected by the mutual game of free water weakening and strengthening. The strength of rock increases first and then decreases with the increase of water saturation time. The dynamic compressive strength of phosphate rock saturated for 3 months is the smallest, which is 25.9 % ~ 28.5 % lower than that of saturated for 48 hours, and 7.0 ~ 19.7 % lower than that of natural rock. Water saturation can improve the rate sensitivity of phosphate rock to dynamic compressive strength. The crushing morphology of ore rock is closely related to its strength. The larger the dynamic compressive strength of ore rock, the larger the fragmentation after crushing. In the same strain rate range, the average particle size after impact crushing from large to small is saturated for 48 h, natural state and saturated for 3 months.Long-term saturation ( such as 3 months and above ) will significantly reduce the strength of phosphate rock and make the crushing more thorough. At this time, the unit consumption of explosives can be appropriately reduced to avoid the use of excessive energy, so as to avoid safety hazards such as flying stones.
- 1
-
Optimization and Stability Analysis of Isolation Pillar Thickness for Open-pit to Underground Mining
Abstract:
In response to the safety thickness and stability issues of isolated pillars during the process of open-pit to underground mining, a particle safety factor calculation method and numerical simulation based on the unified strength theory of double shear were used in a domestic open-pit to underground metal mine as the engineering background to dynamically simulate and compare the mining site under different isolation pillar thicknesses and different mining steps. The results show that: (1) When the width of the mining room is 20 meters, the optimal safe thickness of the isolated mining pillar in the mining area is 39.37 meters. At this time, the minimum safety factor of the bottom particles of the isolated mining pillar reaches the critical threshold of 1, which meets the safety requirements of the project. Considering the actual engineering situation, the thickness of the isolated mining pillar should be set to 40 meters. (2) The safety factor of particles at the bottom of the isolated mining pillar shows a non-linear growth trend with increasing thickness, and the spatial distribution characteristics are similar: the safety factor in the contact area of the surrounding rock on the upper wall is lower than that on the lower wall, with a difference of about 5.7-15; The safety at the center of the bottom edge in the width direction is lower than that at both ends, with a maximum difference of 5; The length direction shows an increasing trend from west to east, with a maximum difference of 15. (3) The disturbance caused by mining leads to the deterioration of the stability of isolated pillars. As the exposed area of the goaf increases, the danger range expands, and the safety factor value of particles closer to the goaf decreases. The danger area migrates from the center of the bottom to the midpoint of the long side as the mining progresses. The study proposes an optimization method for the thickness of isolated pillars based on the critical safety thickness threshold and dynamic risk evolution, which can provide reference for the safety thickness of isolated pillars in open-pit to underground mining.
- 1
-
Analysis of Green and Low-carbon Development Level and Influencing Factors of the Mining Industry in Guangxi under the "Dual Carbon" Coals
Abstract:
The green and low-carbon transformation of the mining industry is a key part of achieving high-quality development. Under the vision of the "dual carbon" goals, the evaluation index system for green and low-carbon development levels has been constructed from the perspectives of economic development, production scale, environmental pressure, and low-carbon levels. It then evaluates the green and low-carbon development level of Guangxi's mining industry through a game-theoretic combination of the empowerment method and the cloud object meta-model with improved cloud entropy. Finally, it analyses the influencing factors by combining the grey degree of correlation and the obstacle factors. The research results show that in 2005-2022, the evaluation grade of the green and low-carbon development level of Guangxi extractive industry has experienced a process of slowly rising, then declining, then rising and stabilising, and has been gradually upgraded from the lagging stage to the advancing stage, with obvious fluctuations as a whole. Furthermore, the grey correlation analysis indicates that the proportion of large mining enterprises in the mining industry, the level of development and development potential are the key influencing factors, with grey correlations of 0.8626, 0.8087 and 0.7938, respectively. The obstacle factors show a phase change, and the indicators under the low carbon level and environmental pressure guideline layer obstruct the green low carbon development level in 2005-2018 is larger; the obstacle level of the indicators under the economic development guideline layer is more significant in 2018-2022. This study provides theoretical support and reference for the green and low-carbon transformation of the mining industry.
- 1
-
Research on particle migration behavior of total tailings paste during pipeline transportation based on ERT
Abstract:
In the process of pipeline transportation, the whole tailings paste slurry will have particle migration behavior, and the plunger flow structure will appear along the radial direction of the pipeline. Due to the non-transparency of the filling slurry and the deep underground characteristics of the pipeline, it is undoubtedly difficult to study the dynamic migration behavior of particles from the microscopic perspective. Based on the connection between particle migration behavior and paste concentration change in pipeline transportation, electrical resistance tomography (ERT) technology is adopted in this paper, and the mass concentration is 60%. The change of electrical conductivity of paste slurry with a coarse particle content of 0, 5%, 10% and 15% during pipeline transportation was studied by using Maxwell equation and concentration index to achieve the characterization of particle migration behavior during pipeline transportation, and to clarify the strong relationship between particle migration behavior and settlement behavior during pipeline transportation. The results show that the conductivity and slurry concentration in the center of the pipeline are stronger than those near the side wall, which indicates that the particle migration behavior occurs during the transportation of paste slurry and the plunger flow structure is formed. And the equation between slurry concentration and coarse particle content in the plunger area is regression,. The results show that with the increase of coarse particle content, the slurry concentration in the plunger area first increases and then decreases, indicating that there is an "optimal advantage" of coarse particle content, which is about 4.3% in this study. At this time, the particle migration effect is the best, and the particle migration forms the strongest bearing structure stability. When the coarse particle content is high, the particle settlement gradually exceeds the particle migration capacity, and a large number of particles accumulate at the bottom of the pipeline, affecting the stable operation of pipeline transportation, indicating that there is a "balance point" of the coarse particle content, which is about 9.6%. In this case, the particle migration capacity and settlement effect cancel each other during pipeline transportation. Through the above research, it is shown that ERT system can monitor the real-time change of the concentration in the pipeline during slurry transportation, which is helpful to judge whether the coarse particles settle in the pipeline transportation process, and provide experimental support for the particle structure flow of "fine particles bearing, coarse particles being loaded" formed in the pipeline transportation process, which is of great significance in reducing the pipe blocking phenomenon during the paste filling pipeline transportation.
- 1
-
Study on the strength of reasonable filling body in stope in safety pillar mining
Abstract:
Aiming at the strength optimization problem of filling body in the newly delineated recoverable area of the security pillar of a gold mine, the determination and verification of the strength parameters of the filling body were systematically carried out through the research path of multi-method fusion. In view of the limitations of the traditional single method, the three-dimensional collaborative analysis method of empirical formula calculation, elastic-plastic mechanics theory analysis and FLAC3D numerical simulation is innovatively used to focus on the regulation mechanism of different strength filling bodies on stope stability and rock movement. Finally, the optimal filling scheme considering both safety and economy is constructed. The main research results are as follows: (1) Through empirical formula and theoretical calculation, it can be seen that the reasonable maximum strength of filling body is in the range of 0.72 ~ 1.99 MPa ; (2) The improvement of the strength of the filling body can effectively control the horizontal deformation of the wellbore and the displacement of the rock strata around the stope; (3) When the filling body strength of the upper upward drift filling method stope and the deep shallow hole shrinkage subsequent filling method stope is set to 2.0 MPa, it can effectively control the movement of the rock strata in the mining area, ensure the stability of the stope, and take into account the economic cost to achieve a balance between safety and economy.
- 1
-
Study on optimization of pipeline transportation performance of high concentration tailings slurry
Abstract:
Tailings slurry pipeline transportation is an important part of mine tailings discharge. Reasonable pipeline transportation parameters directly affect the efficiency of mine tailings discharge. In order to explore the variation law of flow resistance of mine tailings slurry in the process of pipeline transportation, based on the indoor tailings pipe transportation test system, the orthogonal ring pipe test under multi-factor working conditions such as different tailings slurry flow rate, transportation pipe diameter and slurry concentration was carried out. The influence of single factor and multi-factor interaction on the flow resistance of tailings slurry transportation was studied, and the pipeline transportation parameters of tailings slurry were optimized. The results show that : 1 ) The F value of the established regression model is 4660.66, the P value is less than 0.0001, and the fitting value R2 is 0.997, indicating that the model has high reliability. The model can well characterize the changes of the resistance along the slurry transportation under different flow rates, different slurry flow rates and different pipe diameters ; 2 ) The resistance loss is sensitive to the change of slurry flow rate. When the flow rate is low ( i.e., 1m / s ~ 2m / s ), the slope of the resistance loss curve is small. When the flow rate is greater than 2m / s, the resistance loss curve is steeper, the slope is larger and increases sharply. 3 ) Under the action of multiple factors, the influence degree of interaction from large to small is the interaction of tailings slurry flow rate and mass concentration, the interaction of tailings slurry flow rate and conveying pipe diameter, and the interaction of slurry mass concentration and conveying pipe diameter. 4 ) The optimized pipeline transportation parameters are as follows : the slurry transportation concentration is 56 %, the slurry transportation speed is 1.6m / s, and the pipeline diameter is 127 mm. At this time, the pipeline transportation resistance is 0.242kpa / m. According to the optimized pipeline transportation parameters, the indoor test verification is carried out. The resistance along the pipeline transportation is 0.233 kpa / m, and the error between the experimental value and the predicted value is 3.7 %, which is within the controllable range. This shows the accuracy of the prediction model. At the same time, the resistance along the transportation slurry is small, which meets the requirements of long-distance transportation. The test results can provide theoretical support for the design of high mass concentration and high efficiency tail discharge pipeline transportation of mine tailings slurry.
- 1
-
Research on Safe and Efficient Mining Technology of Hanging Wall Orebody in Deep Open Pit
Abstract:
Hanging wall mining, as a transitional scheme between open pit mining and underground mining, is of great significance to ensure the seamless connection of mine in time, space and output. In view of the complex geological conditions that the orebody is located under the high slope and close to the open air transportation system, the two-step strip upward horizontal slicing and filling mining method is adopted, and the FLAC3D numerical simulation software is applied. The stability of stope, slope and open-air transportation system in stope of hanging wall mine is simulated and analyzed. The results show that the plastic zone range, stress concentration degree and displacement of stope, slope and open surface transportation system are kept at a low level when the mining method is used to mine the hanging side ore body. There is a negative correlation between the distance between stope and side slope and stope stability during stope mining. The research results can provide theoretical reference for mining hung wall orebodies in similar mines.
- 1
-
Research on ground temperature storage and cooling technology of Sanxin gold and copper mine in Hubei Province
Abstract:
In order to improve the underground operating environment, combined with the characteristics of abandoned roadways in the constant temperature zone of the mine, it is recommended to adopt the formation cold storage and cooling technology in the mine. The abandoned roadway and inclined shaft in the middle section of -160m are used as pre-cooled roadways, and the pre-cooling fan is added in the middle section of -220m, and the pre-cooling fan is turned on in winter, so that the cold air is stored in the pre-cooled roadway to reduce the rock temperature, the pre-cooling roadway is closed in spring and autumn, the pre-cooling fan is turned on in summer, and the pre-cooled air is circulated into the underground for use. Under the action of the above-mentioned cooling measures, the wet-bulb temperature of the working face was reduced to within the requirements of the regulations of 27°C, and the wind speed increased by 17.4% compared with that before the cooling measures, which achieved outstanding results and provided an economical and feasible underground cooling scheme for mines with the same type of problems.
- 1
-
Analysis of the Diffusion Characteristics and Influencing Mechanism of Dust Concentration in the Open-pit Mine of Qidashan
Abstract:
In order to provide a solid basis for controlling the dust concentration in open-pit mines, the dust conditions at different stages of the production process in open-pit mines were studied. Taking Qidashan open-pit mine as the research object, through on-site investigation, 26 monitoring points were set up in the drilling, blasting, loading and transportation stages. The SDL307 laser dust concentration monitor was used for fixed-point and vehicle-mounted mobile continuous collection. The PLC-16026 meteorological station, which integrates multiple meteorological elements, was used to monitor meteorological parameters. At the same time, the dust migration process was captured by a Canon eos80D single-lens reflex camera. A total of 777 sets of data were obtained. The correlation and regression analysis of these data were conducted to explore the relationship of dust concentration changes, the characteristics of diffusion and distribution, and the influencing mechanism. The results show that when analyzing the correlation between PM2.5 and PM10 concentrations, the cubic curve model has the best goodness of fit, with a determination coefficient R2 of 0.945, which has the strongest explanatory power for the correlation between the two concentrations. The dust concentration and diffusion range in different production stages are significantly different. The dust concentration in a single operation in the blasting stage is the highest, reaching 324.4 μg/m3, and the dust diffusion range is the widest. The dust concentrations in a single operation in the drilling, loading and transportation stages are 59.8 μg/m3, 88.2 μg/m3 and 61.8 μg/m3, respectively. In addition, the dust concentration at the bottom of the pit is significantly higher than that in the closed circle, and the PM10 concentration at the bottom of the pit is almost five times that in the closed circle. Moreover, the concentration differences and fluctuation patterns of different particle types in different areas are different. This study reveals the variation law of dust concentration in open-pit mines and provides key theoretical support for dust control.
- 1
-
Research on the Influence of Flexible - Guided Composite Blades on the Continuous Homogenizing Mixing of Multistate MaterialsLI Chuangqi1, LAI Wei2,3, YUAN Ziqi2, DUAN Hongyu2
Abstract:
In order to achieve efficient, stable and continuous preparation of filling slurry, the computational fluid dynamics (CFD) numerical simulation method was used to study the variation laws of the flow field structure, velocity distribution and mixing characteristics of materials in different states during the continuous mixing process of ordinary rigid blades and flexible - guided composite blades. The influence of flexible blades on the mixing uniformity, mixing time and energy consumption of the slurry was analyzed. Based on this, the superiority of flexible - guided composite blades in the homogenizing mixing of multi - state materials was verified through laboratory experiments, and industrial applications were carried out. The results show that due to their own elastic and deformation characteristics, the flexible blades enable the composite blades to generate a wider range of turbulent kinetic energy, forming an axial - guiding and radial - diffusing mixing flow field, achieving wide - area dispersion of multi - state materials. The degree of particle dispersion is increased by 51.7% compared with that of rigid blades. Under similar mixing effect conditions, the power of flexible - guided composite blades is reduced by 22.3%. Under similar power conditions, the mixing effect of flexible - guided blades is significantly better than that of traditional rigid blades. The flexible - guided composite blades have been applied in mines. After mixing multi - state materials, the slurry has a good homogenization effect, with a concentration reaching 70% and a fluctuation ≤ 1%.
- 1
-
Mechanical analysis of loading and optimization of structural parameters of horizontal ore pillar recycling access road
Abstract:
In order to maintain the stability of underground mining mines, mines reserve various forms of pillars, and horizontal pillars are a common type of pillars, which can cause a large waste of resources. Currently, the key to efficiently recovering horizontal pillars lies in deriving the optimal mine structure parameters. This work is aimed at optimizing the approach parameters during the recovery of horizontal ore pillars in a copper mine, analyzing the force on the roof plate of the quarry, and based on the simple beam structural mechanics model, analyzing the value of tensile stress on the roof plate of the approach plate increases with the increase of the width of the approach, and preliminarily determining the width of the approach and the thickness of the reserved protective layer. And based on FLAC3D numerical simulation, we analyze the influence of approach width on the overall structural stability of the quarry by comparing the different thickness of the reserved layer, and the numerical calculation results match with the theoretical calculation data, and finally we arrive at the optimal approach width and the thickness of the reserved top plate. The research results show that the optimal parameters are: the thickness of the reserved top plate of the approach road is 2 m, and the width of the approach road is 4 m. At this time, the maximum tensile stress on the top plate of the approach road is 0.51 MPa, and the overall structure of the quarry remains stable. The combination of mechanical analysis and numerical simulation can accurately predict the maximum tensile stress in the quarry during the recovery of horizontal ore pillars, which can provide a reliable basis for the safe and efficient recovery of horizontal ore pillars.
- 1
-
Mineralogical study and preliminary beneficiability evaluation of a tungsten ore in Jiangxi Province
Abstract:
In order to provide a basis for the feasibility evaluation of comprehensive utilization of tungsten polymetallic mineral resources, detailed process mineralogy research and preliminary beneficiability evaluation were carried out. Firstly, MLA(Mineral liberation analyzer), combined with microscopic identification, chemical analysis, X-ray diffraction and other analytical methods, was used to study the chemical composition and material composition of the ore, as well as the output forms, embedded grain size and dissociation degree of the main minerals. Then, according to the ore characteristics, the main mineralogical factors affecting the beneficiation effect were discussed and analyzed, and the beneficiation process of “preconcentration tailings discarding - gravity separation and enrichment - selection and quality enhancement - fine mud returning to the team - comprehensive recovery of sulphide ores” was recommended for recovery. Finally, the beneficiation test of the ore was carried out by simplified process of “flotation - shaking table gravity separation - centrifugal gravity separation”. The results show that the raw ore belongs to the granite-type disseminated tungsten ore containing molybdenum and bismuth, with the main valuable component of WO3 at 0.31%, and the main associated components of Mo and Bi at 0.043% and 0.024% respectively. The beneficiation test obtained sulfide ore with Mo grade of 1.40% and Bi grade of 0.79%, and recoveries of 97.51% and 84.67%, respectively; tungsten concentrate with WO3 grade of 69.00% and recovery of 76.58%, together with the WO3 from the fine mud crude concentrate and tungsten intermediate ore, the total WO3 recovery reached 87.04%. The test verified the beneficiability and recovery value of the ore.
- 1
-
Research on Virtual-reality Synchronous Mapping Method for Digital Twin Monitoring of Hydraulic Support Attitude
Abstract:
In order to solve the problems of inaccuracy, poor reliability and high maintenance cost in the internal attitude measurement of hydraulic support, the virtual and real synchronous mapping method of digital twin simulation model of hydraulic support was studied in this paper. Firstly, through analyzing the structure of the hydraulic support, a parametric expression model of the internal attitude of the hydraulic support was established. Then the optimal installation position of the tilt sensor and the 2D LiDAR is determined, and the key technology of sensor data processing is studied. A hydraulic support motion simulation model was constructed, and the parametric expression model of the hydraulic support was programmed into the bottom layer of the simulation system for preliminary application; Finally, based on the laboratory conditions, the proposed virtual and real synchronous mapping method is verified by experiments. The experimental results show that the internal attitude Angle errors measured by this method are all within 2°, which can meet the actual monitoring requirements. This method provides a new idea for the virtual and real synchronous mapping of hydraulic support, and has certain significance for the intelligent construction of coal mine.
- 1
-
Study on the recovery scheme and stability of isolated pillar in an open-pit to underground metal mine
Abstract:
In this paper, a metal mine is taken as the engineering background, and the isolated pillars at the bottom of the open pit are recovered by the method of upward drift filling + artificial false roof. On the basis of this scheme, two mining methods, one mining every other and one mining every five, are put forward. The stability parameters of the stope are calculated by Mathews stability graph theory. The hydraulic radius of the hanging wall of the stope calculated by the upward drift filling method is 1.9 m, which is smaller than the theoretical calculation value of 6.5 m. The maximum span of the roof without support is 3.5 m, which is less than the theoretical calculation value of 6.09 m. Then, FLAC3 D numerical simulation is used to simulate the excavation process of the ore body. By simulating and analyzing the displacement, maximum tensile stress, maximum compressive stress and plastic zone after the excavation and filling of the stope, the results show that the maximum compressive stress and maximum tens
- 1
-
NbS-based ecological safety monitoring strategy for the whole life cycle of mines in Guangdong province
Abstract:
In order to meet the regulatory needs for systematic, rule of law, scientific, long-cycle and democratic regulation of mine ecological safety in the context of the new era, research is being conducted to build a comprehensive regulatory framework on nature-based solutions (NbS). The framework is based on eight design guidelines: problem object, design scale, natural attributes of the solution, benefit assessment, solution feasibility, solution management process, adaptive management model, and sustainability, and focuses on the whole life cycle of mining, including mine survey and design, mining operation and pit closure and maintenance phases. Aiming at the risks and challenges faced by the ecological safety supervision of mines in Guangdong Province, such as the contradiction between ecological environmental protection and economic development of mines in Guangdong Province, the overlap between the development space and protection space, and the serious ecological and environmental problems caused by mining development, this study discusses seven aspects: forward-looking layout, source control, process supervision, strengthening of nature, synergizing with nature, multi-party co-management, and technological innovation. the innovative paths and strategies of mine ecological safety supervision in Guangdong Province have been proposed. This aims to provide a scientific basis for ecological safety supervision of mines in Guangdong Province and nationwide.
- 1
-
Study on optimization of delineation range of shaft security pillar in a gold mine
Abstract:
Aiming at the problems of serious ore storage of security pillar, restricting mine productivity and sustainable development caused by the traditional method of security pillar delineation in a gold mine, FLAC3 D was used to analyze the influence of different security pillar delineation angles on the stability of wellbore and surrounding rock, and the scope of security pillar was re delineated. The research shows that : ( 1 ) The ground pressure activity of No.13 vein is positively correlated with the delineation angle of the security pillar. When the delineation angle increases, the released mineable amount and the number of production stopes increase. ( 2 ) When the delineation angle exceeds 75 °, the ground pressure activity is significantly intensified, especially after the deep stope mining, which increases the risk of wellbore instability. It is suggested that the angle of the safety pillar should be controlled at 75 ° and below to ensure the safety of the wellbore. ( 3 ) By optimizing the delimitation angle of the security pillar, the volume of the overlying ore is reduced from 1192955.0 m 3 to 545256.7 m 3, and about 54.3 % of the ore resources are released, which not only improves the utilization rate of mineral resources, but also provides scientific guidance and empirical support for the sustainable development of the mine.
- 1
-
Suggestions for the adjustment of the the third category mineral resources in Yunnan Province
Abstract:
Yunnan Province is a major province in terms of mineral resources. In recent years, it has also been a major player in infrastructure construction. Construction projects such as highways, railways, airports, and water conservancy projects have kept the demand for sand and gravel aggregates in Yunnan Province robust. However, the type of the third category mineral resources in Yunnan Province are less, the existing resources are unevenly distributed, and the time and space of infrastructure construction are differenti, in addition, due to the impact of the ecological protection red line in Yunnan Province, it is difficult to establish new mining rights in some areas, some counties (cities,districts) lacking resources, need to import resources from adjacent areas, which greatly increases the use cost of sand and gravel aggregates.In order to efficiently utilize resources and alleviate the pressure of uneven supply of sand and gravel aggregates in local areas, based on relevant laws, regulations, and policy documents, and referring to the experience of other provinces in the classification of the third category mineral resources, through field research, an evaluation study was conducted from three aspects: resource endowment, market economy, and existing usage. The results showed that increasing granite, basalt, dolomite, tuff, and sandstone (other) as the third category mineral resources is scientifically feasible. Increasing mineral resources can be used as a supplement to mineral resources in resource deficient areas, while reducing mining management risks and illegal mining behaviors, which is conducive to the development and utilization of sand,gravel and soil mineral resources.
- 1
-
Based on the response surface method, the influence of the preparation conditions of causticized starch in the reverse flotation desilication process of iron ore was optimized.
Abstract:
This study employed the Box-Behnken design of response surface methodology to systematically analyze the effects of causticization time, causticization temperature, and causticization ratio, as well as their interactions, on the recovery rate of iron concentrate. The results indicated that causticization temperature had the most significant impact on the recovery rate, with the order of significance being: causticization temperature (B) > causticization time (A) > causticization ratio (C). The main interaction was between causticization temperature and causticization ratio (BC). The optimal causticization conditions were found to be a temperature of 94.90°C, a time of 80 minutes, and a ratio of 0.07. Under these conditions, the recovery rate of iron concentrate reached 63.65%, an increase of 1.3% compared to the initial conditions. Infrared spectroscopy analysis revealed a significant enhancement in the intensities of the O-H, C=O, C-OH, and C-O-C characteristic peaks of the optimized causticized starch, suggesting a more stable intramolecular hydrogen bond network and a more ordered structure, thereby significantly improving its inhibitory performance. This study demonstrates the efficiency and reliability of response surface methodology in optimizing flotation reagents and provides a theoretical foundation and technical support for the industrial application of causticized starch.
- 1
-
Two-dimensional Seepage Diffusion Study of MICP-reinforced Sandy Soil Media Considering Multiple Rounds of Grouting
Abstract:
Microbially Induced Calcium Carbonate Precipitation (MICP) technology shows remarkable potential in tailings pond ecological reinforcement projects due to its environmental friendliness and sustainability. However, the quantitative study of seepage diffusion during microbial grouting remains a key constraint to its application. Aiming at multi-round microbial grouting reinforcement scenarios and systematically considering the synergistic effect of the sandy soil medium on the slurry diffusion behaviour during the dynamic attenuation of permeability coefficient and the evolution of porosity gradient, the infiltration radius based on the column diffusion theory was constructed by combining the multi-scale experiments and theoretical modelling with a combination of one-dimensional sand column experiments, intermediate-scale 2D planar physical model experiments, and FLAC3D numerical simulations of coupled flow and solidity. The prediction model was constructed based on the column diffusion theory. The results of the two-dimensional planar model show that: the vertical dimension is dominated by gravity effect, and the slurry diffusion shows significant asymmetry, forming a pagoda-like distribution with the bottom wide and the top narrow (the final diffusion radius at the bottom is 3.91 times of the diffusion radius at the top); and the horizontal dimension follows the radial attenuation law of diffusion effect, and the reinforcement strength is inversely proportional to the centre distance of the slurry injection pipe. Validation of the theoretical model showed that the relative errors between the maximum diffusion radius and the predicted value for the 2nd→5th rounds of grouting were 43.89%, 57.40%, 63.72%, and 62.37%, respectively, and the error ranges were within reasonable limits. This provides a quantitative theoretical framework for the optimisation of MICP process parameters and engineering-scale diffusion prediction, which is of great significance for optimising the engineering stability assessment and risk prevention and control strategies.
- 1
-
Research on the force Characteristics of Cutting and Crushing on Deep-sea Cobalt-rich Crust by the helical pick
Abstract:
Based on the helical pick cutting and crushing method, this study analyzed the behavior and process of cutting and crushing cobalt-rich crust ore bodies by helical pick, and a dynamic model of ore body cutting and crushing based on pick cutting was constructed. Based on the Hertz-Mindlin with bonding (HMB) contact model of EDEM, a simulation model of the cutting and crushing of cobalt-rich crust ore body by picks was established. A simulation ore body crushing test platform was prepared, and verification tests of the force characteristics of single pick and full pick cutting and crushing were carried out. The overall trends of the test and simulation results were basically consistent. In the test, when the cutting speed was from 0.05 m/s to 0.1 m/s, the cutting resistance increased by 20%; when the cutting depth was from 10 mm to 30 mm, the cutting resistance increased by 110%, and the fluctuation coefficient increased by 43.2%. The cutting resistance decreased by 15.97% and 9.93% respectively by using the vibration-assisted crushing method when the cutting depth was 20 mm and 30 mm, and the fluctuation intensity increased by 16.7% at a cutting depth of 30 mm. The test results show that the cutting resistance is more sensitive to the cutting depth than the cutting speed, the greater the depth or the faster the feed speed, the greater the load fluctuation, and the vibration-assisted crushing method helps to reduce the required cutting force but increases the cutting vibration. The research results can provide a reference for the study of operation parameters and the development of cutting heads for deep-sea cobalt-rich crust cutting and crushing technology.
- 1
-
Study on dynamic change of dump slope stability after long duration rainfall
Abstract:
In order to reveal the dynamic change law of seepage field and stability of the slope of the soil discharge field after long calendar rainfall, taking a soil discharge field in DRC as an example, applying the geotechnical theory of Van Genuchten model fitting the characteristic curve of soil-water, and utilizing the Geo-studio software to simulate the seepage field of groundwater and limit equilibrium analysis of the slope of the soil discharge field after long calendar rainfall, the results show that: 1, the initial stage of rainfall is dominated by vertical infiltration, and the later stage is dominated by lateral seepage. Vertical infiltration is dominant in the early stage, and lateral seepage is dominant in the late stage, the initial water level rises faster, and then gradually decreases after 2 days, and then gradually stabilizes after 25 days.2. The safety coefficient fluctuates up and down within 1 day, and then decreases and then increases after 1 day, and then the safety coefficient is minimum before and after 4 days, and basically tends to be stabilized after 20 days.3. The minimum moment of the safety coefficient does not lie in the moment of rainfall, but during the process of the water level decreasing at the end of the rainfall. After the end of seepage water level stabilization safety coefficient tends to stabilize, rainfall impact lag is obvious. The results of the study can provide guidance for mine safety production and management.
- 1
-
Fig.1 Statistics of solid waste output and disposal of smelting units in the company
Abstract:
The western mining group is faced with the problems of large solid waste reserves and high treatment cost. In order to realize the reuse of solid waste in the group and reduce the filling cost of each mine goaf, taking Xitieshan and Subei Bolun Iron Mine as the pilot objects, the consumption and cost of solid waste were analyzed by means of indoor experiment and field industrial test, and the cost reduction research based on industrial smelting solid waste instead of mine filling cementitious material was carried out. The results show that the new solid waste-based cementitious material is used to fill the first and second steps of the mine in the tin mine. It is estimated that the 28 d filling strength is 2.5 MPa and 1.1 MPa, respectively, and the filling strength can reach 86.5 % of the pure cement ratio. The annual consumption of solid waste is 14625 t, and the annual filling cost is saved by 2.0361 million yuan ; Subei Bolun Iron Mine adopts a new formula to treat the filling layer that only needs to be self-supporting in 2025. It is estimated that the 28 d strength is 0.99 MPa, the filling strength can reach 38.5 % of the pure cement ratio, the solid waste can be consumed 5623 t, and the filling cost increases by 432 400 yuan. For the western mining group company, the total solid waste can be treated 20248 tons, and the filling cost can be saved by 1.6037 million yuan.
- 1
-
Study on the effective thermal conductivity model of fractured rock mass under normal stress
Abstract:
The temperature field of deep tunnels and the development of deep mineral resources involve the thermal conductivity of rock mass. For the nonlinear change rule of effective thermal conductivity of fractured rock body under normal stress, based on the two-part Hooke’s model and effective thermal conductivity series-parallel theory, a theoretical model of effective thermal conductivity of fractured rock body under normal stress is established, and the influence of model parameters on the effective thermal conductivity of fractured rock body under stress is analysed, and through the numerical simulation results of the change of temperature field in Nigel Tunnel, it verifies the engineering application of the model. Reliability. The results show that: the theoretical model prediction results are in good agreement with the test data, the effective thermal conductivity of the fractured rock body in the low stress stage is mainly affected by the soft part of the pore-slit closure, and the effective thermal conductivity increases nonlinearly with the increase of the stress, and the effective thermal conductivity of the fractured rock body in the high stress stage is mainly affected by the hard part of the pore-slit closure, and the effective thermal conductivity increases slowly in an approximately linear manner with the increase of the stress; The larger the angle between the fracture surface and the direction of heat transfer, the smaller the effective thermal conductivity of the rock at the same stress, and the higher the degree of non-linearity with the stress change; Comparing the numerical simulation results with the measured data, the thermal conductivity of the intact rock mass is on the large side, the effective thermal conductivity obtained by the stress-independent ETC model is on the small side, and the ETC-TPHM thermal conductivity model considering the compression and deformation of the rock mass is more in line with the actual measured values.
- 1
-
Deep learning classification of coal mine flotation froth based on 3D point cloud data
Abstract:
Aiming at the problems of spatial information loss in traditional 2D images and the one-sidedness of single-cell data during the identification of coal slime flotation froth, a full-process multi-cell feature fusion method based on 3D point cloud data is proposed. This method uses the Percipio Infrared Binocular FM855-E1 industrial camera to collect the 3D point cloud data of the froth throughout the entire flotation machine process. Preprocessing and data augmentation techniques are adopted to optimize the dataset. A PointNet network with non-shared weights is utilized to extract the high-dimensional features of each cell. After dimensionality reduction by a multi-layer perceptron, these features are fused into full-process features through a concatenation function. Finally, the working condition categories are determined by a combination of a multi-layer perceptron and the Softmax function. The experimental results show that the classification accuracy of the full-process multi-cell network reaches 94.89%. Compared with the 67.59% of the single-cell network, 46.75% of the two-cell network, and 84.35% of the three-cell network, it is increased by 27.30%, 48.14%, and 10.54% respectively. The loss value is reduced to 0.2169, and the misjudgment rate drops significantly. This research demonstrates that the full-process multi-cell network effectively enhances the robustness of the model. The full-process features remarkably improve the accuracy of identifying flotation working conditions, providing a highly reliable 3D visual solution for the intelligentization of coal slime flotation.
- 1
-
Study on the effect of new room-temperature collector MY on the behavior of hematite reverse flotation
Abstract:
Anshan-type hematite accounts for about 55.20 % of the total identified iron ore resources in China, and its flotation generally requires high temperature (about 35 ℃ or more) conditions, which increases the production cost. This not only incurs substantial energy consumption but also results in a relatively low recovery rate of mineral resources. The present study focuses on the self-developed MY-type collector for hematite and quartz flotation behaviour, with a comparative analysis against the oleic acid flotation system. Utilizing detection and analysis techniques such as contact angle, Zeta potential and infrared spectroscopy analysis, the mechanistic roles of oleic acid and the MY-type collector on the mineral surfaces has been discussed. The results of single-mineral flotation experiments show that the MY-type collector, within the temperature range of 15~35 ℃, the pH value of 11.5, and the dosage of 200 mg·L-1, achieved a quartz recovery rate exceeding 88.00 %, marking a notable improvement of 14.75 % over the oleic acid flotation system. At 25(±2) °C, under the interaction of the three agents, starch, CaO, and trap, the difference in single mineral recovery of quartz and hematite was 89.25 % under the MY flotation system, which significantly improved the difference in the flotation of quartz and hematite compared to the oleic acid flotation system. The results of mechanism analysis show that MY-type traps in the quartz mineral surface electrostatic adsorption, hydrogen bonding and chemical bonding cooperation and other synergistic adsorption, in the hematite surface to molecular adsorption, electrostatic adsorption is dominated by the MY due to the existence of its structure of the S=O, -NH2, C=O and other reactive groups, the formation of the coupling of multiple active sites synergistic action, to enhance the ability of the quartz capture and increase the difference in flotation between quartz and hematite can effectively promote the separation of quartz and hematite in the room temperature reverse flotation system. MY can effectively promote the separation of hematite and quartz in the room temperature reverse flotation system due to the coupling and synergistic effect of multiple active sites, which enhances the trapping ability of quartz, and increases the difference in the floatability between quartz and hematite.
- 1
-
Comparative study on the accuracy and efficiency of unmanned aerial vehicle surveying in open-pit mines
Abstract:
In previous studies on unmanned aerial vehicle surveys in open-pit mines, most research focused on using a single type of UAV for data collection and analysis, without considering the efficiency of both field and office operations. Taking the Xiangtan Iron and Steel Group's Xiangxiang Dolomite Mine as the engineering background, this study employed two types of UAVs, the DJI Matrice 300 RTK and the MAVIC 3E, to conduct field data collection at four different flight altitudes in the mining area. For office data processing, four different ground control point layout schemes were selected for each scenario to analyze the accuracy of measurement points under different flight altitudes and varying numbers of GCPs. Additionally, the time consumption for both field and office operations in each scenario was recorded to evaluate the efficiency of UAV surveys in open-pit mines. The results show that the M300 RTK equipped with a five-lens camera generally achieves higher accuracy than the MAVIC 3E in its intelligent shooting mode under the same conditions, although accuracy decreases as the flight altitude increases. Under the same flight altitude conditions, the accuracy of both UAVs improves with an increase in the number of GCPs, but the improvement is marginal. At the same flight altitude, the field operation time for both UAVs is similar, but the office processing time for the MAVIC 3E is only 1/10 to 1/5 of that for the M300 RTK. In large elevation difference non-coal open-pit mines, using the MAVIC 3E's real-time terrain-following mode combined with a GCP-free approach eliminates the need for field GCP setup and significantly reduces office data processing time. This approach ensures accuracy while greatly improving the efficiency of UAV surveying in mining operations. Moreover, the cost of the MAVIC 3E is only 1/5 of that of the M300 RTK, demonstrating a clear cost advantage.
- 1
-
Flow Characterization of Different Water Content Ore Release Processes in Sharply Inclined Extremely Thin Veins
Abstract:
To explore the flow characteristics of different water content ore in the release process of sharply inclined extremely thin veins, and thus optimize the mining process and improve the resource recovery rate, a full-size numerical model of the ore release from the restricted space of sharply inclined extremely thin veins is constructed by combining the physical experiments and numerical simulation methods. The discrete element simulation parameters are determined by performing angle of repose calibration tests on ore with different water contents. The full-size ore release numerical simulation is carried out to analyze the release characteristics of ore with different water contents at different stacking heights. The results show that the water content of ore has a significant effect on the flow characteristics of ore: when the water content is 15%, the ore release flowability is optimal, the flow rate is large and stable, and it is “first-in-first-out”; with the increase of water content, the flowability is distorted, and it gradually turns into “first-in-last-out”, and the flow rate decreases, which can't satisfy the requirement of simultaneous operation of multiple ore release ports. In addition, at 4% water content, the release height has little effect on the flowability of the ore rock, and as the water content increases, the increase in the release height deteriorates the flowability of the particles at high locations, with severe deterioration of the flowability at 15% water content.
- 1
-
Research on Flood Risk Zoning Based on Graph Neural Network Clustering
Abstract:
Flash floods and debris flows are common hazards in mountainous open-pit mining areas, making the classification of flash flood risk levels crucial for mine safety. To address the issue of spatial relationships being overlooked in existing risk classification methods, this study proposes a flash flood risk classification method based on graph neural network (GNN) clustering for open-pit mining areas. The Baiyunebo mining area is selected as the study area, and the method consists of three main steps: (1) Remote sensing images of the mining area are divided into grid cells, each represented as a node with features such as elevation, slope, aspect, and precipitation. (2) The cosine similarity method is used to calculate the environmental feature similarities, and spatial relationships between similar nodes are represented as edges to construct an adjacency matrix. (3) The constructed graph and the corresponding adjacency matrix are input into the network model, which adopts an encoder architecture consisting of GraphSAGE with graph sampling and aggregation, and the Graph Attention Mechanism (GAT)., optimized with the Kullback-Leibler (KL) divergence loss function to predict the clustering of flash flood risk levels.Experimental results show that the clustering accuracy of the model reaches 87.5%, outperforming traditional clustering algorithms such as K-means, hierarchical clustering, and random forests by 11.2%, 9.4%, and 5.3%, respectively. This demonstrates the effectiveness of the method in flash flood risk classification for open-pit mining areas. The study highlights that GNNs can better capture complex spatial and structural relationships, providing valuable insights for flash flood prevention in open-pit mining areas.
- 1
-
Safety evaluation model and application of mining area around shaft security pillar
Abstract:
The safety of shaft safety pillar is an important guarantee for safe mining in mines. Taking a gold mine as an example, aiming at the optimization of the delineation range of the safety pillar, the investigation and analysis of the ground pressure activity in the mining area were carried out. Combined with the main risk factors, a safety evaluation model considering multiple influencing factors was proposed to evaluate the current safety of the mining area around the shaft safety pillar. The research shows that the shallow ground pressure activity is caused by the combined action of geological factors and mining disturbance. The deep local deformation and failure are caused by the comprehensive influence of mining depth, in-situ stress increase and geological factors. The safety of the safety pillar is affected by three types of factors, such as natural conditions, mining disturbance and production management, involving 11 influencing factors. The safety assessment results of 41 stopes show that the safety level of most stopes is grade II, and the overall safety situation is good. The occurrence conditions of ore bodies, geological structure, mining methods and the distance between shaft security pillars are the main factors affecting the safety of pillars. The area with good continuity of ore body and high stability of surrounding rock has better safety, and the area far away from the wellbore security pillar has less influence on the wellbore area and higher safety.
- 1
-
Application progress of data-driven digital twin technology in smart mines
Abstract:
With the intensification of China's population aging, the traditional mine operation mode relying on the experience of technicians can no longer meet the needs of the sustainable development of modern mining. There is an urgent need to introduce advanced technologies such as digital twins to promote the transformation of mines towards intelligence and greening, so as to effectively respond to the challenges of increasing resource demands, intensifying environmental pressures and safety in production. Research shows that, by virtue of its data - driven characteristics, digital twin technology can provide accurate simulation for mine construction plans. By integrating multi - source data such as geological and geographical data, a virtual model corresponding to the real mine is constructed to optimize the layout planning and reduce resource waste and risks in actual construction. In terms of mine production safety, various equipment and environmental data in the mine, such as gas concentration and equipment operation parameters, are monitored in real - time, providing a strong guarantee for mine safety management. For mine production optimization, digital twin technology analyzes a large amount of production data, such as mining volume and transportation efficiency, to dig out potential optimization points, adjust the production process, improve production efficiency and reduce production costs. Although digital twin technology has a wide range of applications, due to the current cognitive level, technical level and infrastructure limitations, the constructed virtual model cannot fully ensure authenticity and reliability, resulting in deviations in prediction results. By constructing a complete standard system, enhancing data fusion and processing capabilities, optimizing intelligent algorithms and models, and strengthening interdisciplinary cooperation and technology integration, the transformation of mines towards unmanned and intelligent directions is promoted.
- 1
-
Research on advanced ming of high-grade sill pillars and false roofs construction in a copper-nickel mine
Abstract:
In response to the mining technical difficult problems of high-grade sill pillars caused by insufficient preparation in mining levels and stopes, as well as significant fluctuations in ore output grade in a copper-nickel mine, three mining methods were proposed: the mechanized upward drift backfilling mining method, the downward drift backfilling mining method, and the combined backfilling mining method of upward drift and strip with medium-depth hole. The mechanized upward drift backfilling mining method was determined to be the optimal solution with comparative analysis of the advantages, disadvantages, technical and economic indexes of these methods. The classical Janssen theory of granular pressure was used to calculate the overburden load of sill pillars. The thickness of the artificial false roof exhibits a negative correlation with the maximum compressive stress by calculating with the simply supported beam and soft support weak plate mechanical models. Based on the artificial roof form and the mechanical properties of cementitious materials, the backfilling construction parameters for the artificial roof were determined: a roof thickness of 7.0 meters and a backfill strength (R28d) of 4.5 MPa. To address quality, safety, and cost issues in the construction of the artificial roof, an optimized scheme was studied and determined. The optimal solution (Scheme 1) was to use the artificial roof as the direct roof of the 10-meter crown pillar in the lower stope. The roof was designed with a combination of bottom, waist, and top reinforcement, with main parameters of HRB400Φ25＠250~500mm. The applications demonstrated that the proposed mining method is feasible, achieving a pillar mining rate of up to 82%, and the ground pressure activity is stable. Additionally, the construction process of the artificial roof is highly operable and safe, enabling the safe and efficient extraction of sill pillar resources. This study also provides technical references for similar mining operations.
- 1
-
Research on the causes and treatment measures of large blocks produced by fan-shaped hole blasting in broken ore-body
Abstract:
In the sublevel caving mining method, the blasting effect of the fan-shaped blast holes is difficult to control, but it significantly affects the ore recovery effect. Focusing on the problems of high large block rate and poor ore recovery index as well as poor safety of mining operations in the 1580m sublevel caving stope under the condition of broken ore-body in the West Second Mining Area of Longshou Mine, the main reasons for the high large block rate were analyzed to be the upper sublevel edge holes being buried by the blast heap and not being fully blasted, and the severe blockage of the blast holes in the current sublevel and the failure to load explosives in place. To reduce the large block rate in the stope, a series of technical measures were proposed, including optimizing the cross-sectional form and size of the drifts, improving the blasting parameters of the fan-shaped holes, introducing through-hole equipment suitable for the working environment, testing the pre-loading technology, and strengthening the blasting quality management. As a result, the large block rate in the stope was successfully reduced from 16% to 5%, the ore recovery index was improved from 68% to 82%, and the safety of the stope was significantly enhanced.
- 1
-
Risk Assessment of Geological Disasters in Mining Cities Considering Mining Disturbance and Ecological Security Patterns
Abstract:
In order to reflect the particularity of the inducing factors of geological disasters in mining cities and enrich the vulnerability connotation of geological disasters in mining cities, the mining disturbance index was included in the geological disaster risk assessment system, and the impact of geological disasters on the regional ecological security pattern was included in the vulnerability evaluation system.The results of the geological disaster risk assessment in Daye City show that the areas of extremely high, high, medium and low risk are 96.93 km2, 308.45 km2, 391.14 km2 and 769.76 km2 respectively, accounting for 6.19%, 19.69%, 24.97% and 49.15% respectively; the extremely high and high-risk areas are mainly distributed in the regions with frequent mining activities such as Jinhu, Dajiupu, Jinshandian, Huanqiao, Luqiao, Lingxiang, Chengui and Liurenba; abandoned mining areas and mining disturbances are the main causes of geological disasters, and it is necessary to strengthen the restoration and governance of abandoned mining areas and adopt green mining methods.
- 1
-
Research on Drill Bit Detection Method for Underground Mining Operations Based on YOLOv8-WBG
Abstract:
Mine drill bit detection is a key link to ensure the safety of mine underground operation, but the existing detection models based on deep learning have shortcomings in feature extraction ability and detection efficiency. In order to improve the detection performance, a bit detection algorithm YOLOv8-WGB based on improved YOLOv8n is proposed. Firstly, the WIoU loss function replaces the traditional CIoU loss function, which enhances the focus on key features. Secondly, GAM attention mechanism is introduced to enhance the global information interaction ability of YOLOv8 backbone network, reduce information loss and enlarge the global dimension characteristics. Finally, BiFPN structure is added, and different weights are assigned to the feature maps of different scales to achieve the optimal fusion. The experimental results show that the detection speed of YOLOv8-WGB is 6.1% higher in P, 4.8% higher in R and 4.4% higher in mAP@0.5 than that of YOLOv8n, and the FPS is 173FPS higher than that of YOLOv8s. The experimental results draw the following conclusions: Based on YOLOv8n, the algorithm achieves the same detection speed as YOLOv8s, while taking into account the accuracy and speed of the algorithm, and shows a good performance in the detection task of underground mining bits.
- 1
-
SU Sichao, WANG Jun, YANG Tianyu
Abstract:
Aiming at the problem of short pumping distance and easy plugging of pipe in Datun Tin mine, it is proposed to add copper slag tailing fine material to the gravel to improve aggregate grading to reduce pipeline transport resistance. The results show that the mass ratio of crushed stone to copper slag tailings is 6:4, and the mixture can form a skeleton structure to achieve the maximum compactness, and further rheological, paste bleeding and flow tests are carried out. Under the mass ratio of crushed stone to tailings of copper slag 6:4, the mixture ratio of crushed stone to tailings of copper slag, which can satisfy the strength of filling body, the paste is not separated and can be self-levelled, is further determined. According to the actual filling pipeline of 32# stope in Datun Tin Mine, the pipe transport resistance of 9 groups of slurry is analyzed by using Fluent numerical simulation software. The results show that adding appropriate amount of copper slag tailings to the gravel can effectively improve the pumping performance of the slurry, and achieve a single pump transport distance of more than 2000m. In the industrial test, the cement dosage is 240kg/m3, the mass concentration is 83% of the slurry, the single pump transport distance is 2052m, and the export kinetic energy is still abundant, which solves the original filling problem.
- 1
-
Research on technology optimization and capacity transition of downward drift mining with backfilling in a copper nickel mine
Abstract:
In response to issues such as restricted deep mining operations using the backfill method and decreased production capacity due to adverse geological conditions in a copper-nickel mine, this study conducted research on the optimization of the downward drift backfill method, production capacity verification, and production transition plans. By integrating the current mining technical conditions and existing mining methods, the primary technical objective was to achieve continuous and efficient mining in the backfill method area. Three technical schemes for the downward drift backfill method were proposed: along-strike layout, vertical-strike layout, and oblique layout. Through a comprehensive comparative analysis of the advantages, disadvantages, and technical-economic indicators of each scheme, the along-strike layout was ultimately determined as the optimal solution.The study also proposed a production capacity calculation method under continuous ore extraction in panel areas. Based on the orebody occurrence characteristics of the mine's middle section, the panels were categorized into three types for production capacity verification calculations. Subsequently, the production capacity of each sublevel was reviewed and calculated. A corresponding production transition plan was formulated in line with the mine's actual production conditions, clarifying the work deployment during the transition period.The research results indicate that the optimized backfill method is technically feasible, safe, and efficient, with a highly operable production transition plan. This study provides technical support and reference guidance for mining production and capacity transition in this mine and similar mining scenarios.
- 1
-
Study on dynamic mechanical failure characteristics of rock mass containing hole under impact dynamic loading
Abstract:
Borehole pressure relief is a common prevention and control measure of high-stress dynamic load threatening roadways. It is of great significance to adopt a reasonable pressure relief aperture for current rock burst roadway protection. To study the effect of pressure relief hole aperture on the dynamic characteristics of surrounding rock under dynamic load, dynamic load impact experiments were carried out on pre-drilled samples with different bore diameters by separated Hopkinson pressure bar test system, and the effects of pressure relief hole aperture on the dynamic mechanical properties, failure characteristics and energy dissipation of the samples were analyzed. The experimental results show that the increase in pore diameter causes a decrease in dynamic peak strength and peak strain, and the decrease of dynamic strength gradually decreases with the increase of pore diameter, while the increase of peak strain gradually increases. The final failure mode of the samples with holes under dynamic load is mainly X-shaped tensile shear composite failure, but the Angle between tensile fracture and loading direction, the development degree of the initial tensile fracture before closing and the development degree of the far-field fracture are affected by the size of the aperture. The existence of holes indirectly provides stress conditions for the development of cracks in the sample, so the fractal dimension increases with the increase of the aperture, but when the aperture exceeds a certain threshold, the sample cracks have not been developed in time, and the fractal dimension begins to decrease. The energy dissipation ratio of the sample is similar to the crushing characteristic, and it increases first and then decreases with the increase of the aperture, which is mainly related to the delay effect of different apertures. The research results have certain guiding significance for the optimization of pressure relief aperture of deep roadway threatened by dynamic load.
- 1
-
Experimental study on copper-sulfur separation flotation of a low-grade iron tailings
Abstract:
In Chengchao Mining Company of WISCO, copper, sulfur and other valuable resources were recovered from tailings by flotation process of first mixing and then separation. The sulfur concentrate obtained by copper and sulfur separation flotation had high copper grade, resulting in low copper recovery. Therefore, for mixed flotation concentrate, the effects of separation flotation conditions such as regulator, inhibitor, collector and pulp concentration on copper and sulfur separation flotation were studied in detail in this study. The results show that under the optimal conditions of separation flotation, the concentration of pulp is 30%, the amount of activated carbon is 120 g/t, the amount of quick lime is 6000 g/t, and the amount of Z-200 is 30 g/t. Copper concentrate with Cu grade of 16.00% and recovery of 54.87% can be obtained by using one rough, two fine and one sweep. The grade of sulfur concentrate S is 35.10% and the recovery rate is 33.57%. The Cu content in the sulfur concentrate is reduced to 0.115%. Compared with the on-site process, the recovery rates of Cu and S are increased by more than 9% and 7%, respectively. The copper content in the flotation tailings is 0.013%, the sulfur content is 6.89%, and the copper content in the sulfide is 0.0063%, 97.97% of the sulfur element mainly exists in the sulfate. The results showed that the copper sulfur was fully recovered from the tailings.
- 1
-
Simulation Study on Support of Auxiliary Slope in Deep Mining of a Metal Mine
Abstract:
The stability of deep roadway is one of the key points of deep mining, but also one of the difficulties. Based on the engineering background of deep mining in a hard rock metal mine, FLAC3D was applied to construct a numerical model based on the in-situ stress test results, and five representative elevations were selected to quantitatively analyze the stability of auxiliary slopes with different support schemes from four aspects: stress, displacement, strain and plastic zone. The results show that: (1) When the arc arch is supported by C30 shotcrete with a thickness of 100 mm, the auxiliary ramp can maintain stability at the elevation of 2 325 m and above, but it is unstable at the elevation of 2 175 m and 1 950 m, and the support needs to be strengthened; (2) The bottom plate is laid with C30 concrete with a thickness of 300 mm, which is unstable in the height range of 2 850~ 1 950 m; (3) Three support strengthening methods were studied respectively: (1) only increasing the shotcrete strength of the arc arch
- 1
-
Study on The Mechanical and Rheological Properties of Gobi Aggregate and Tailings Synergistic Cemented Filling in a Mine and Optimization of Neural Network Prediction Model
Abstract:
To address the issue of high filling costs and poor process stability due to insufficient tailings production at a certain mine, the mechanical and rheological properties of Gobi aggregate-tailings synergistic filling were studied. The filling ratio was optimized, and a strength prediction model was developed to provide theoretical support for low-cost, high-efficiency filling. Through single- and multi-factor analysis and significance testing, the effects of solid content (74%–78%), sand-to-ash ratio (1:6–1:12), Gobi sand addition (0%–30%), and curing age (3–28 days) on the filling body’s strength and flow resistance were explored. L-tube rheological tests were used to measure yield stress and viscosity coefficients, analyzing the mechanism of conveying resistance. Improved Random Forest (RF) and Convolutional Neural Network (CNN) models were constructed on the MATLAB platform to predict compressive strength. The results showed that the uniaxial compressive strength of the filling body increased with solid content, sand-to-ash ratio, and curing age. The optimal strength was achieved with 20% Gobi sand addition (28-day strength of 5.20 MPa), while excessive addition reduced flowability. Flow resistance increased with concentration, and resistance was minimized with 10%–20% Gobi sand addition (0.38–1.16 MPa/km). In the neural network models, CNN outperformed RF in prediction accuracy, with the test set coefficient of determination (R2) of 0.97034 and mean absolute error (MAE) of 0.10181, reducing errors by 31% compared to RF (R2=0.90127, MAE=0.14795). Appropriate Gobi sand addition (≤20%) optimized both strength and flowability, and the CNN model accurately predicted compressive strength, providing reliable support for optimizing filling ratios and process parameters. The findings offer technical guidance for utilizing low-grade aggregates and reducing filling costs in similar mines.
- 1
-
The Influence of Endwall Roughness and Ore Size Distribution on Ore-Release Performance
Abstract:
To investigate the impact of wall roughness and ore gradation on ore drawing efficiency, physical experiments were conducted based on a single-slice, single-entry ore drawing model. Joint Roughness Coefficient (JRC) was introduced to quantify the end wall roughness. Five levels of wall roughness and two ore gradation conditions were tested. The variation rules of ore recovery rate and dilution rate and the characteristics of the shape development of the effluent were obtained. The research findings indicate that wall roughness and ore particle size distribution have significant effect on ore fluidity, subsequently resulting in changes in recovery rate and depletion rate. With the decrease of fine particle proportion and end wall roughness in ore grading, the ore recovery rate shows an increasing trend, while the dilution rate increases first, then decreases and then increases with the increase of fine particle proportion and end wall roughness. when the ore gradation is rich in fine particles and the JRC value reaches 11.2, the ore flow velocity decreases, resulting in reduced recovery rate and increased dilution rate. Under Group B ore grading and the JRC value is 0, ore mobility is the best, the recovery rate is the highest (75.15%), and the dilution rate is the lowest (32.09%). Additionally, as the proportion of fine particles in the ore gradation decreases and wall roughness diminishes, the lateral axis of the drawbell develops more rapidly, while its height develops more slowly, contributing to an increase in ore recovery.
- 1
-
Diametrical core deformation analysis method and its application in deep in-situ stress measurement
Abstract:
In-situ stress measurement is one of the indispensable basic work in deep resource mining engineering. Core radial deformation analysis method (Diametrical Core Deformation Analysis, hereinafter referred to as DCDA) by measuring the diametrical deformation of the core sample, without being limited by the drilling depth, the deep borehole stress information has the advantages of convenient operation, reusable. Based on the principle of DCDA method, a core diametrical deformation measuring device based on high precision laser ranging technology is developed. The highest measuring accuracy can reach 0.001mm. A core orientation method based on borehole image and core surface scanning is proposed. The geographic orientation of core samples is determined by comparing borehole wall image and core surface image, and the horizontal principal stress direction is determined by the radial ellipse shape of oriented core. The method was applied to the in-situ stress measurement of a 1200m exploration borehole in a phosphate mine in Guizhou province, and the hydraulic fracturing method was carried out for verification. The test location range was 440m~1005m. The results showed that the maximum horizontal principal stress direction measured by DCDA method was NE66°~NE81°. The maximum horizontal principal stress direction measured by hydraulic fracturing method is NE64°~NE80°, and the results measured by the two methods are basically consistent. The difference of horizontal principal stress measured by DCDA method and hydraulic fracturing method is less than 5.0%. The results show that the DCDA method combined with borehole image and core surface scanning is feasible. Based on the case analysis of DCDA method in deep hole in-situ stress measurement, the further application of this method is discussed, and a new idea of in-situ stress measurement is put forward, which combines radial deformation analysis method and differential strain analysis method.
- 1
-
Study on the safety of fiber-reinforced composite for explosion-proof enclosure in coal mine
Abstract:
To address the need for lightweight equipment in coal mine environments, a non-metallic lightweight explosion-proof enclosure made of glass fiber/epoxy resin (GF/ER) was developed and its safety was explored. Through comprehensive testing of mechanical and thermal stability, coupled with finite element analysis, it was established that the GF/ER explosion-proof enclosure satisfies the pertinent explosion protection standards required for coal mine settings. Furthermore, this composite enclosure achieves a significant weight reduction of more than 50% relative to metallic counterparts of equivalent dimensions. Furthermore, the prototype GF/ER explosion-proof enclosure, classified as Type I Ex equipment, has a volume of 19.5 liters and can be widely applied in various explosion-proof devices. The successful design and validation of the GF/ER explosion-proof enclosure provide a foundational reference and theoretical basis for advancing the lightweight design of future mining equipment.
- 1
-
The influence of dynamic disturbance-induced damage on the characteristic stress and acoustic emission response characteristics of sandstone
Abstract:
A series of dynamic impact and uniaxial compression tests were conducted to investigate the effects of dynamic disturbance-induced damage on the mechanical behavior and acoustic emission (AE) response characteristics of sandstone specimens. The test results showed that the P-wave velocity of the sandstone specimens gradually decreased with increasing impact velocity, while internal damage increased. The ratio of crack closure stress to strength increased with impact velocity. However, the ratios of crack initiation stress and damage stress to strength gradually decreased. During the deformation and failure process, AE activity exhibited significant stage-specific evolutionary characteristics. The intensity and frequency of AE activity showed notable changes with the evolution of internal damage in the rock. These findings provide a theoretical basis for evaluating the stability of surrounding rock and designing support systems under blasting disturbances.
- 1
-
Study on Comprehensive Utilization of Iron Tailings in Central Shandong
Abstract:
At present, a large number of iron tailings can not be fully and effectively utilized due to their low content of useful minerals, weak magnetism, fine crystal particle size and complex and difficult separation. Therefore, in order to solve this problem, this paper studies a kind of low-grade ore from a concentrator in Luzhong area, Shandong Province.Firstly, the properties of the raw ore were analyzed and tested, and the main iron-bearing mineral in the raw ore was magnetite. According to the properties and characteristics of the ore, the test of the raw ore respectively screening-gravity concentration-medium magnetic separation-grinding-medium magnetic separation-gravity concentration process scheme ( scheme I ), screening-gravity concentration-medium magnetic separation-grinding-medium magnetic separation-flotation concentration process scheme ( scheme II ) and screening-gravity concentration-medium magnetic separation-grinding-medium magnetic separation-gravity concentration-gravity concentration-heavy tail flotation concentration process scheme ( scheme III ) three schemes of experimental research. The final results show that the useful iron minerals in these ores are finely disseminated and closely associated with iron silicate minerals with relatively strong magnetism. Therefore, in order to obtain higher grade iron concentrate, gravity separation or flotation shows obvious advantages over magnetic separation, so Scheme II or Scheme III can be selected according to the actual situation. The iron grade of the final tailings is high, which can be used as a cement iron correction agent, and finally realize tailless discharge, which is conducive to environmental protection.
- 1
-
Research and application of comprehensive safety evaluation of metal and non-metal underground mine based on mine safety expert experience and knowledge
Abstract:
Based on the experience knowledge of mine safety experts, establishes a multi-level comprehensive evaluation index system and evaluation model of underground mine safety from the aspects of legal procedure requirements, safety production organization guarantee, safety education and training, double prevention mechanism construction, production system security, emergency management, dangerous goods and dangerous operation management and outsourcing project management. Fully absorb the experience knowledge of industry experts, and based on the weight of the weighted calculation, and then establish safety evaluation set for determination to obtain the comprehensive safety evaluation results of metal and non-metal mines. Practical applications have demonstrated that the results of comprehensive safety evaluations largely conform to the actual conditions of mines, which can effectively improve the scientificity and practicality of the comprehensive safety evaluation of metal and non-metal underground mines. The evaluation process can help companies identify weak links production safety, providing a theoretical basis for further consolidating safety foundations, strengthening safety management, and improving safety levels.
- 1
-
Experimental study on beneficiation of an arsenic-zinc polymetallic ore in Inner Mongolia
Abstract:
The zinc concentrate of a zinc polymetallic ore in Inner Mongolia contains excessive arsenic and the grade of arsenic concentrate is low. The flotation process of copper, zinc and arsenic was systematically studied. The combination of lime, sodium humate and zinc sulfate was used to inhibit arsenic-sulfur minerals, and the combination of ethyl xanthate and Z-200 collector was used to enhance the selectivity of copper flotation. Lime and NY were used as inhibitors to inhibit arsenic, copper sulfate activates sphalerite, and ZC collector improved zinc recovery in the zinc flotation. The copper-zinc flotation tailings were further grounded (-0.074mm 68.10%), and the arsenic recovery rate was improved by the combination of sulfuric acid, silicate solution and copper sulfate in the arsenic flotation. The copper concentrate with grade of 29.35%, recovery of 82.17% and arsenic content of 0.46% was obtained, zinc concentrate grade was 46.85%, the recovery rate was 86.34%, and the arsenic content was 0.52%. The arsenic concentrate contained arsenic grade of 32.20% and recovery of 87.94% by selective flotation process. When the grinding fineness reached -0.074 mm 80.13%, the dissociation degree of copper and zinc minerals increased significantly, and the arsenic content of copper and zinc concentrate decreased by 85% and 87% respectively compared with the original process. It provided a technical reference for solving the beneficiation problem of high arsenic zinc polymetallic ore.
- 1
-
Intelligent Prediction of Roadway Surrounding Rock Loose Circle Thickness Based on Interpretable Machine Learning
Abstract:
In order to improve the accuracy and reliability of the measurement of the thickness of the loose circle of the surrounding rock of the roadway, a high-precision prediction model of the thickness of the loose circle (PSO-Stacking) is proposed, which can explain the artificial intelligence algorithm to crack the black box effect of the machine learning algorithm and explain the prediction mechanism, and the engineering example is verified in Xinglongzhuang Coal Mine. Combined with the SHAP analysis model decision, the influence of the characteristics of the surrounding rock loose circle is revealed and the interpretability is improved. The results show that the PSO-Stacking model performs well in predicting the thickness of the loose circle, with high prediction accuracy and small error. The test set R2 is 0.957, RMSE and MAE are 0.118 and 0.087, respectively. The global interpretability analysis of the prediction model shows that the buried depth of the roadway and the degree of mechanism development have the greatest influence on the prediction results. Local interpretation analysis shows that the buried depth significantly affects the thickness of the loose circle of high-strength surrounding rock, while the joint development has little effect. The model is applied to Xinglongzhuang Coal Mine, and the average error between the prediction result and the real value is only 4.31 %. It shows that the proposed model can effectively predict the thickness of the loose circle of roadway surrounding rock and reveal the influence of characteristics, which provides a scientific reference for the support and effectiveness evaluation of surrounding rock in time and meets the needs of engineering practice.
- 1
-
Stability Analysis of Jointed Rock Slopes with Different Protective Measures
Abstract:
In order to investigate the effect of different protective measures on the stability of jointed rock slopes, the Particle Flow Code in two-dimensions (PFC2D), strength reduction method and failure criterion characterized by a coherent fracture plane are used to reveal the failure characteristics of jointed rock slope when the parameters of contact model have been reduced until the critical rock failure state has occurred. Then the safety factor and microcrack evolution as well as energy dissipation of jointed slopes under different protective measures including slope-cutting, anchor cable reinforcement and without any protective measures are comprehensively researched. Research shows that when the parameters have been reduced until the critical rock failure state has occurred, the main failure mode of jointed rock slope is tensile-sliding failure. The slope-cutting measure can partially improve the stability of the slope, and the anchor cables installed at a zone where is below the joint surface and close to the the intersection of the steeply inclined fracture and the gentle slip surface can significantly improve the stability of the slope.The number of microcracks and dissipated energy generated during the process of adjusting the slope to a stable state with anchor cable reinforcement measure are less than those generated with the slope-cutting measure, and the number of microcracks and dissipated energy with slope-cutting measure are less than those generated without any protective measures. The microcracks with anchor cable reinforcement measure are mainly distributed in the area near the anchor head. The research results can provide reference for the slope engineering of similar open-pit mines.
- 1
-
Experimental study on low alkalinity clean beneficiation of high sulfur copper ore containing magnetiteHuang Chunfu1, QI Zhongxu2,3, Jiang Xu2,3*, Ding Shengqiang1, Chen Chunlin1, Li Jie2,3
Abstract:
A copper sulfur mine in Guangdong Province adopts the process and reagent system of "high alkali copper sulfur separation weak acid sulfur separation". In response to the problems of high acid and alkali consumption, low flotation efficiency, and high safety and environmental risks on site, experimental research on ore properties and mineral processing technology has been conducted, and a "low alkali no acid" process scheme has been determined. A low alkali copper sulfur green and efficient separation reagent system based on ore properties has been developed. The results showed that the use of B18 to capture copper minerals, CD-S2 to replace some lime for sulfur suppression, copper sulfate to replace sulfuric acid activation, and butyl xanthate to capture floating sulfur can effectively replace the on-site "high alkali weak acid" chemical system. Through the process of "one coarse, three fine, three scans, one fine scan" for copper selection, copper tail weak magnetic separation for magnetic sulfur, and "one coarse, one fine, two scans" for non-magnetic sulfur selection, a closed circuit test was conducted to obtain copper concentrate with a Cu grade of 20.84% and a recovery rate of 88.11%, as well as a comprehensive sulfur concentrate with an S grade of 46.12% and a recovery rate of 94.68%. Compared with the original process, the copper grade and recovery rate in the copper concentrate increased by 2.59% and 1.94%, respectively, and the sulfur concentrate indicators were comparable. The pH value of the crude slurry in the closed circuit test Reduced from 11 to 8.5, achieving clean and efficient separation and recovery of copper and sulfur in a "low alkali no acid" environment.
- 1
-
Research and thinking on the construction of standard system for comprehensive utilization of mineral resources in China
Abstract:
In order to further implement the "People's Republic of China (PRC) Mineral Resources Law" on promoting the rational development and utilization of mineral resources, in the field of comprehensive utilization of mineral resources, under the guidance of the current "Standard System of Natural Resources" and other important top-level designs, it is of great guiding significance to carry out the research on comprehensive utilization of mineral resources in China by using logic and systematic thinking, and it is also an important measure to support the new round of strategic action of prospecting breakthrough. The standard system is a scientific organic whole formed by the standards in a certain range according to their internal relations. Relying on the theory and method of natural resources standardization, supported by the existing research results of comprehensive utilization of mineral resources, and within the framework of standardized administration and technical logic in the field of mineral resources, the research work of standardization of comprehensive utilization of mineral resources, standardization of reserves management, standardization of planning management and standardization of achievement data management is carried out in a targeted manner, and following the construction principles of the standard system, China's "Mineral Resources" is constructed from three dimensions: foundation, category use and subcategory use. Relying on this standard system, through the analysis and research, the problems existing in the standardization research of comprehensive utilization of mineral resources in China are put forward, and the key directions and shortcomings to be filled in the next standardization work are given to further lead the overall research work of comprehensive utilization of mineral resources in China.
- 1
-
Research and Analysis of Dynamic Changes in Airflow Field under Ultra-Deep Well, Heavy Load, High-Speed Lifting Conditions
Abstract:
With the gradual depletion of shallow resources in mines, deep shaft mining has become an important method for resource extraction. A study was conducted on a domestic ultra-deep shaft metal mine under construction with heavy-load high-speed hoisting. The research focused on the dynamic changes in the air flow field around the hoisting containers by analyzing different shaft container arrangement methods and different operating conditions. The study investigated the distribution patterns of aerodynamic pressure on the hoisting containers. Using the standard k-ε turbulence model from fluid dynamics, Fluent numerical simulations were performed to analyze the airflow state inside the shaft during container operation. The aerodynamic pressure distribution around the containers during hoisting was examined, and the container offset was calculated, revealing the characteristics of the aerodynamic forces and lateral swing behavior experienced by the hoisting containers in the shaft. The results indicate that when two oppositely moving hoisting containers pass each other in the shaft, significant aerodynamic impact forces and moments are generated. The lateral aerodynamic forces in a dual-container shaft arrangement are greater than those in a four-container shaft arrangement, and the piston effect is more pronounced in the dual-container setup compared to the four-container setup. From an aerodynamic perspective, the study concludes that a four-container arrangement is preferable for ultra-deep shaft hoisting, followed by a dual-container arrangement.
- 1
-
Sublevel medium and long hole subsequent filling mining method in high cold and high altitude mines Application and optimization
Abstract:
Taking Jiama copper polymetallic mine in the high cold and high altitude area as the research background, considering that some stope layout areas in the underground mine are within the range of crushing oxidation zone, there are roof collapse and side wall collapse in the production process, and there are ore gullies at the bottom of the segment-medium and deep-hole stope to facilitate ore extraction, the triangle pillar at the bottom of the stope cannot be effectively mined due to poor filling body quality after the completion of production. Through field investigation, theoretical analysis and reference to other mines of the same type, the combined support scheme of shotcrete net and long cable grouting is proposed to pre-reinforce the stope roof to ensure the ore mining in the range of crushing oxidation zone. On the other hand, the medium and long hole blasting technology is optimized, and the bottom pillar can be recovered without trench in the same row by adding shallow holes. Industrial tests show that: By adopting the optimized method of "pre-controlled roof reinforcement measures + replenishment of shallow hole and same row mining bottom column", the sub-level medium and long hole subsequent filling method can effectively improve the stability of stope roof and increase the recovery rate of ore resources. Compared with the original scheme, the comprehensive production capacity of stope is increased by 21.54%, and the loss and dilution rate is only 8%, which has excellent popularization and application value in the underground production area.
- 1
-
Study on the Effect of Plastic Expansion Agent on the Properties of Mine Grouting Materials
Abstract:
Adding plastic expansion agent is an effective measure to improve the volume stability of mine grouting materials. In this paper, plastic expansion agent was used to prepare grouting material for mining. The influence of plastic expansion agent on its performance, rheological properties, mechanical properties and volume stability was investigated. The results show that with the increase of plastic expansion agent content, the working performance and rheological properties of the grouting materials are improved, the compressive strength and flexural strength decrease, the plastic expansion rate increases gradually at 3 h, but the influence of volume deformation is small in the middle and late stages. The total porosity and average pore size of the hardened slurry increased significantly after the addition of plastic expansion agent. When the addition rate was higher than 0.12%, the proportion of capillary pores and large pores increased more. Considering the performance parameter requirements of grouting materials, it is more suitable when the plastic expansion rate is in the range of 0.04%~0.08%.
- 1
-
Study on Detection and Treatment Scheme of Collapse Loose Area in Kalatongke Copper-nickel Mine
Abstract:
The caving mining of 1 # ore body in Kalatongke Copper-Nickel Mine has caused a large collapse loose area. The collapse loose area has caused the deterioration of the mining environment of the upper ore rock, and the resources are difficult to release and threaten the safety of the shaft. In order to further detect and control this area, the loose boundary was preliminarily determined by geological drilling and TRT advanced detection in the early stage. Due to the blockage of the channel, the traditional detection equipment was difficult to approach the target area. The potential area was detected in detail by C-ALS Gyro endoscopic three-dimensional scanning. The scanning clarified the location, shape and volume of the larger loose area, and indicated that the larger loose area existed locally and the overall collapse range tended to be stable. By comparing the three treatment schemes of waste rock backfilling, caving surrounding rock and cemented filling, considering the advantages and disadvantages of each scheme, the cemented filling scheme is selected according to the treatment principle. The actual treatment effect shows that the scheme enhances the regional stability, increases the resource recovery rate by about 30 %, improves the safety guarantee and reduces the environmental impact, which provides scientific basis and valuable experience for mine safety production.
- 1
-
Research on synchronous control of multi-point segmented combined drive system for continuous lifting of large capacity deep vertical shaft
Abstract:
Aiming at the synchronous control problem of each segmented drive motor in the continuous lifting system multi-point segmented drive system under long-distance, large capacity, and high power conditions, an improved deviation coupling control strategy with speed and torque dual compensation is adopted based on the traditional deviation coupling control method. Build a synchronous control numerical model for a six motor segmented coupled drive continuous lifting system with a lifting capacity of 7.5 million tons/year, a lifting height of 1500 meters, and a single motor driving power of 2000 kW. Compare and analyze the synchronous tracking performance of traditional deviation coupling control and improved deviation coupling control under different starting load torques and steady-state load disturbances in the continuous lifting segmented coupled drive system. The results show that the synchronization and stability effects of the multi motor segmented drive system using the improved deviation coupling control are better than those of the traditional deviation coupling control system, verifying the feasibility of applying the improved deviation coupling control in the multi-point segmented drive synchronization control system of the continuous lifting system.
- 1
-
The Evolution of Physical Properties and Shear Characteristics of Andesite under Hydrochemical and Freeze-Thaw Effects
Abstract:
To investigate the effects of hydrochemical and freeze-thaw (HFT) on the physical properties and shear mechanical characteristics of andesite, andesite from the Duolong mining area in Tibet was selected as the research object. Freeze-thaw tests were conducted for 45 cycles under three different hydrochemical environments. The changes in shear mechanical parameters and physical properties, as well as the damage mechanisms, were analyzed from both macroscopic and microscopic perspectives. The results show that:As the number of freeze-thaw cycles increases, both the physical properties and shear mechanical parameters of andesite in all three hydrochemical environments exhibit a deterioration trend, with the most significant damage observed in the acidic environment.Shear test results indicate that the decrease in cohesion is more pronounced than that in the internal friction angle, and the failure modes differ among environments: shear failure in acidic environments, shear fracture failure in neutral environments, and tensile shear failure in alkaline environments. A shear mechanical prediction model based on shear test data was established, with an error of less than 10%, which can effectively predict the cohesion and internal friction angle values of the rock after long-term freeze-thaw cycles in different chemical environments.A quantitative analysis of the damage caused by hydrochemical and freeze-thaw actions based on shear test parameters reveals that freeze-thaw cycles cause more damage to the andesite than hydrochemical effects.The findings provide important reference data for engineering applications such as slope stability evaluations.
- 1
-
Study on optimization of mining in transition area from large area up-cut and fill method to sublevel open-stop method
Abstract:
The ore body above 180m level in the west section of Dahongshan Copper mine belongs to the gently inclined medium-thick ore body, which was originally mined by the point-column upward horizontal slicing-and-filling method. However, with the continuous expansion of the mining scope and level, the projected exposed area also gradually increased, and the surrounding stress concentration became increasingly obvious. In the stope to be mined, the roof safety hazards became more and more serious. According to the unique characteristics of ore body and the actual situation of the site, in order to solve the existing problems, the optimization study of transition zone mining was carried out, and the original method was optimized to adopt the segmented open stope and subsequent filling stoping with medium and long hole mining, and the cemented pillar transition zone was constructed by cemented filling. However, the stope of the two methods in the transition zone is within the plastic zone, and the layout of the mining preparation is not consistent, so further research is carried out. The research results show that the transition area adopts segmented open stope with subsequent filling, and cemented filling forms cemented pillars. The maximum plastic zone height of stope roof is 7~8m, and the height difference of adjacent stopes is about 15~17m. The layout of backfill air lane is not affected, and mining conditions are available. The field investigation results show that the stope engineering in the transition area is stable on the whole, and the resources in this area are safely and efficiently extracted.
- 1
-
Experimental study on multi-scale damage effects of high temperature damaged gneissin deep ground environments
Abstract:
To explore the damage effect of fractured rock mass in the deep geothermal high-temperature environment, with gneisses as the research object, micro-CT scanning was conducted to obtain the micro-fracture evolution characteristics under high temperature. In combination with three-dimensional percolation simulation and uniaxial compression test, the permeability and strength deterioration laws as well as the microstructure were analyzed. The results indicate that as the temperature rises from 20℃ to 800 ℃, the mass loss rate of gneiss increases to 1.72%, and the strength decay rate amounts to 36.83%. The surface porosity rises from 1.74% to 6.28%, and the dispersion of pore distribution also escalates. The three-dimensional fractures expand dynamically during the heating process, and the volume proportion of the connected fractures increases significantly. The thermal damage effect on the structure leads to the cracking of the rock, resulting in the reduction of impermeability and bearing capacity. The high-temperature effect causes thermal damage to the microstructure of gneiss, and the primary pores gradually expand with the increase in temperature. In light of the damage effect of the high ground temperature environment on the fractured rock mass, effective fracture sealing measures should be adopted in practical engineering to ensure the safe operation of deep mining.
- 1
-
Early-properties and mechanisms of high-fluidity slag and desulfurization gypsum composite alkali-activated filling material mixing with seawater
Abstract:
Mixing water significantly influences the properties of alkali-activated filling material (AAM). In practical applications, due to limited construction conditions and time constraints, seawater and other unconventional water sources may be utilized as mixing water, potentially affecting the physical and mechanical properties of AAM in unpredictable ways. To address this issue, the effect of seawater concentration on setting time, fluidity, and strength was analyzed using high-fluidity slag and desulfurization gypsum composite alkali-activated filling material (HSD-AAM) as the subject of study. Additionally, the early hydration mechanism of HSD-AAM was investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric-differential scanning calorimetry (TG-DSC) tests. Results indicate that as seawater concentration increases, the condensation time of HSD-AAM decreases, fluidity diminishes, and both flexural and compressive strength improve. When compared to pure water, the fluidity of HSD-AAM decreased by 12%, while the initial and final setting times were reduced by 28% and 27%, respectively. Additionally, the 1-day flexural and compressive strength increased by 18% and 19%, and the 7-day strengths rose by 27% and 17%. Seawater accelerates the hydration process of C-(A)-S-H gel, AFt, and Friedel salt—particularly Friedel salt—thereby enhancing the early strength of HSD-AAM. However, it has minimal impact on the formation of Ca(OH)2 crystals.
- 1
-
Sun Shuang,Wen Yanliang,Zhao Jiangdong,Fu Zhiyong
Abstract:
With the transition of metal mining into deep mining stages, multi-outlet ore drawing has become a common method in deep mines. However, significant arching phenomena have been observed during the ore drawing process. To investigate the impact of multi-outlet ore drawing on granular ore arching, a lateral pressure testing system for granular material flow was utilized. Physical similarity simulation experiments were conducted under single-outlet, double-outlet, and triple-outlet conditions. The lateral pressure distribution patterns of granular ores were analyzed under varying ore extraction methods and filling heights, providing insights into the arching phenomena. The results indicate that when the filling height is 75 cm, the arching phenomenon in multi-outlet ore drawing is more pronounced and exhibits the highest strength. The arching location is minimally influenced by the ore drawing method, with significant arching generally occurring 55 cm above the ore outlet. Moreover, under triple-outlet conditions, a series of small consecutive arches also forms approximately 30 cm above the ore outlet. The filling height further affects the formation and location of arching under triple-outlet conditions. At a filling height of 85 cm, significant arching occurs 55 cm and 75 cm above the ore outlet, with a tendency for arching in lower regions. When the filling height increases to 95 cm, the region of significant arching extends downward.
- 1
-
Study on the effect of structural surface parameters on rock damage characteristics under true triaxial unloading-dynamic perturbation
Abstract:
By carrying out true triaxial loading-disturbance tests on granite with different structural surfaces, using acoustic emission system to monitor the rock damage process, we investigated the damage characteristics and acoustic emission evolution of rocks with different structural surfaces, analysed the relationship between the structural surface parameters and the damage results of the samples, and compared the macroscopic and microscopic differences of the rocks with three kinds of damage results. The results show that: (1) when the length of the structural plane is 20 and 30 mm, the rock samples are cracked and damaged, and when the length is 50 mm, the rock samples are prone to rock explosion; when the length of the structural plane grows and the inclination angle increases, the damage of rock samples tends to change from shear to internal shear and external cleavage, and when the length of the structural plane is smaller, the inclination angle has a weaker influence on the damage pattern of the rock samples; and grouting of structural planes weakens the degree of destruction of the rock samples; (2) the three kinds of damage RA-AF density maps of rock samples with different ratios of tensile and shear regions; (3) different structural surface parameters, the crack distribution and amplitude of the upper position of the structural surface, the position of the structural surface, and the lower position of the structural surface of the rock samples differ significantly; (4) based on the characteristic analysis of the coefficient of variation (CV) of the b-value and the r-value, it is concluded that the generation of shear cracks and tensile cracks in the granite under different structural parameters under the dynamic perturbation is significantly different from the generation of tensile cracks. There is a significant difference between the shear crack and tension crack generation in granite with different structural parameters under dynamic disturbance. This study aims to provide theoretical guidance for the disaster prevention and control of mining in deep structure-bearing rocks.
- 1
-
Effect of Ultrasonic-assisted Process on the Flotation of Fine Flake Graphite
Abstract:
In order to improve the fixed carbon content of graphite flotation concentrate, a graphite mine in Luobei, Heilongjiang Province was selected as the research object. The mechanism of typical gangue quartz entering the graphite concentrate was analyzed through pure mineral flotation experiments. The effects of ultrasonic time and ultrasonic frequency on the flotation of artificially mixed graphite and quartz ores were explored. The actual ore flotation test was conducted using an ultrasonic-assisted process, and the influence of ultrasonic pretreatment on the fixed carbon content of graphite concentrate was evaluated. The results of pure mineral flotation experiments showed that graphite formed flocs under hydrophobic action, allowing fine-grained quartz to enter the concentrate through entrainment and inclusion. Ultrasonic can reduce water recovery and quartz flotation by strengthening particle dispersion. The actual ore flotation experiments demonstrated that the open circuit flotation flowsheet of "five regrinding and six cleaner flotation" is adopted, and the graphite concentrate with fixed carbon content of 94.61% and recovery rate of 81.66% is obtained by 6 mins ultrasonic pretreatment during the third to sixth cleaner flotation, and the concentrate grade is increased by 3.1% compared with the conventional process. The results of this study provide a basis for the ultrasonic-assisted process to improve the fixed carbon content of graphite concentrate during the regrinding and reprocessing stages.
- 1
-
Numerical study on plume characteristics under shear action of deep-sea sediments
Abstract:
Sediment plumes generated during the mining of polymetallic nodules have a significant impact on the seabed ecosystem. To explore the sediment resuspension and dispersion phenomena under the disturbance of mining vehicles, a simulation study was conducted based on a finite element analysis Eulerian model. The study analyzed plume dispersion under different rotary speeds (0.1 m/s~0.9 m/s) and indentation depths (33 cm and 18 cm), and evaluated the effectiveness of plume suppression devices. Results indicated that when the flow speed exceeded 0.3 m/s, the plume size and height significantly increased, with the maximum plume height reaching 1.4 m. When the indentation depth was reduced, the plume size and sediment diffusion velocity noticeably decreased. Additionally, with the addition of a plume suppression device, the plume size reduced by about 51%, plume height decreased by 25%, diffusion tendency reduced to 46%. The plume suppression device effectively mitigated the plume, providing a reference approach for reducing plumes in deep-sea polymetallic nodule mining.
- 1
-
Study on the factors affecting the filling quality of Longshou Mine and control measures
Abstract:
Since the Jinchuan Longshou Mine adopted the filling mining process, no systematic research has been conducted on the quality of filling. With the increase of mining depth and the decrease of ore grade, the cost of mining is increasing, so it is necessary to study the quality of filling in order to control the cost of filling. Based on this, this paper takes Jinchuan Longshou Mine downward layered cemented filling method as the engineering background, and systematically carries out a half-year tracking survey on the current situation of mine filling quality, and analyzes the key factors affecting filling quality and their influencing effects, and finally puts forward the filling quality control measures in combination with the results of the survey and the analysis. The results show that the quality of filling materials is poor, the filling body is not completely connected to the top, the strength of the filling body fluctuates greatly, and the number of abnormal stops has a greater impact on the filling quality. Field practice shows that the filling quality can be improved by ensuring the unit consumption of cementitious materials and the quality of filling materials, improving the roofing rate, reducing the frequency of abnormal stops, improving the homogeneity of slurry and determining the reasonable filling concentration.
- 1
-
Synergistic Deformation of Shaft Wall-Cageway Structure under Thermo-Hydro-Mechanical Coupling
Abstract:
This study investigates the thermomechanical-hydrological behavior of the mine shaft wall and tunnel structure using numerical simulation and field monitoring. A beam element model with "node differences" was used to simulate tunnel seam displacement. The results show that temperature increase raised the maximum vertical compressive stress of the shaft wall by 24.35%, while reducing the tunnel beam axial compressive stress by 25.63%, causing a shift from downward to upward curvature. Water head reduction increased the shaft wall vertical stress by up to six times and shear strain by 4.9 times, with axial compressive stress rising by 24.31%. Shaft wall compression caused layered bending in the tunnel beam. Under six conditions, temperature increase and water head reduction resulted in vertical stress increases of 21.1%, 20.8%, 18.8%, and 16.4%, 14.2%, respectively. Tunnel beam axial compressive stress increased with water head reduction by 22.34%, 26.56%, and 29.13%, and decreased with temperature rise by 22.43% and 19.17%. Temperature increase slightly reduced shear strain, and structural deformation exhibited a "superposition effect." Vertical displacement of the tunnel seam at 3AA45, near the shaft wall, was most influenced by the coupled effects. Mathematical modeling showed that water drainage impacts vertical displacement four times more than temperature. These findings are crucial for the safety assessment of shaft wall-tunnel structures.
- 1
-
Study on evolution characteristics of overburden spatial structure and abutment pressure of the superimposed influence zone of deep gobs
Abstract:
To effectively prevent rock burst induced roadway excavation in the superimposed influence zone of gobs, the overburden spatial structure and the abutment pressure distribution and evolution law were studied through numerical simulation under the engineering background of the 71330 track roadway excavation. Subsequently, the preventive measures of rock burst were put forward, and the practicability of measures was verified through on-site microseismic, anchor bolt (cable) load and stress monitoring. The results indicate that there is a U-shaped overburden spatial structure around a single gob, and vertical stress concentration degree in the influence zone of the gob is relatively low; there is a S-shaped overburden spatial structure when multiple gobs appear, and the vertical stress concentration degree is higher in the superimposed influence zone of gobs. The concentration degree of vertical stress around the roadway excavated in the superimposed influence zone of gobs and risk of rock burst further increase. The preventive measures of “releasing - breaking - reducing - resisting” consisted of destressing drill in coal seam, roof blasting, controlling advance speed and strengthening roadway support were implemented, and rock burst was effectively prevented during roadway excavation. The distribution of microseismic events is obviously zonal, and the whole has the characteristics of "high frequency and low energy". The load of anchor bolt (cable) in the surrounding rock of the roadway does not exceed its breaking load. The stress observation values fluctuate significantly within 30 days of deployment, then tend to stabilize and do not reach the warning value. The above results have verified the practicality of the measures for preventing rock burst. The results can provide a reference for the prevention of rock burst under similar conditions.
- 1
-
Study on the Effect of Composite Additive Ratio on the Properties of Fly Ash-Based Mine Filling Materials
Abstract:
Aiming at the problems of low strength of filling body and large surface settlement in the current filling mining process of a coal mine in Jining, the filling material was prepared with fly ash as the main material, lime, β-gypsum, cement, flake alkali and composite additives ( slag, AEA expansive agent, cement clinker are recorded as A, B, C respectively ) as auxiliary materials. The effects of additive ratio on slurry fluidity, uniaxial compressive strength of filling body, hydration products and microstructure were investigated. The results show that there is no linear relationship between the fluidity of slurry and the content of each component in the additive. When other components are constant, with the increase of the content of each component, the strength of the filling body at different curing ages increases first and then decreases. The hydration products of the filling body cured for 28 days under different ratios are basically the same, but the diffraction peak intensity is different. The increase of the content of each component can effectively improve the compactness and pore development of the filling body, and the microstructure deteriorates when the content is excessive. When the content of A, B and C components is 14 %, 6 % and 8 % respectively, the mechanical properties are the best, the early strength ( 8 h ) and long-term strength ( 28 d ) reach 0.75 MPa and 4.33 MPa respectively, the compactness of the filling body is the highest, and the flow performance is excellent.
- 1
-
Mechanical Bearing Effect of Variable Cross-section Pillars in Goaf
Abstract:
Due to the inherent characteristics of the ore body and the quality of the blasting operation, variable cross-section pillars are commonly found in underground mining using the room and pillar method. To investigate the mechanical properties and effects of variable cross-section pillars, a mechanical model of such pillars was constructed, focusing on a limestone mine pillar with a variable cross-section. Expressions for stress and safety factors were derived, and the relationships between stress and safety factors, as well as factors such as diameter d and radius R of the variable cross-section area, were separately studied. Additionally, the characteristics of stress distribution were analyzed. The results indicate that the stress in the variable cross-section pillar gradually varies within the variable cross-section area. The amplitude of this stress decreases as R or d increases, and decreases with the increase of d within the constant cross-section area. Additionally, the safety factor rises with the increase of R, showing a gradually increasing rate of change, which also synchronizes with the increase in d. When compared to a constant cross-section pillar, the variable cross-section pillar exhibits a more uniform stress distribution, superior stress transfer at the junction with the roof, a higher safety factor, and enhanced stability. Numerical simulations and engineering cases confirm the reliability of the theoretical findings.
- 1
-
Prediction of Uniaxial Compressive Strength of Rocks Based on Comparative Analysis of Multiple Algorithms
Abstract:
Accurately and effectively determining uniaxial compressive strength (UCS) of rocks is of great significance for ensuring the safety of mine rock engineering. Based on two datasets, including parameters such as compressional wave velocity (Vp), Schmidt hammer rebound value (Rn), and point load strength (Is(50)), four combination algorithms, namely PSO-BP, PSO-LSTM, CNN-LSTM, and PSO-BILSTM, were selected to predict the optimal UCS using seven regression metrics. The results showed that the four algorithms were ranked in terms of performance using the metric scoring method. The PSO-LSTM algorithm achieved a total score of 27 in Data set Ⅰ and 21 in Data Set Ⅱ, indicating that it performed the best in predicting UCS. The parameter sensitivity analysis revealed that Is(50) and BTS were the most influential parameters for predicting UCS in Data set Ⅰ and Data Set Ⅱ, respectively, suggesting that using parameters with strong correlations yielded better prediction results. The research findings provide guidance for determining the uniaxial compressive strength of rocks.
- 1
-
Study on the microscopic mechanism of en-echelon fracture in shale under compression-shear loading
Abstract:
In order to investigate the effect of shear slippage on the communication and connection of multiple tensile fractures in shale, the PFC2D method was used to study the fracture process of shale with different bedding orientations based on the compression-shear tests. The initiation, propagation and connection characteristics of the en-echelon fractures and their bedding directional effect were analyzed. The communication and connection mechanism of shear slippage on multiple tensile fractures was subsequently revealed. The control laws of various main factors on the en-echelon fractures were explored. The results demonstrate that: (1) The en-echelon tensile cracks that inclined to the shear plane are created first near the shear plane in the process of compression-shear fracture of shale. As the propagation of en-echelon cracks gradually slowed down or even stopped, the shear cracks initiated from both ends of the shear plane and then rapidly extended and penetrated the en-echelon cracks, forming a shear fracture zone. (2) The en-echelon fractures morphology formed in the process of compression-shear loading shows significant bedding directional effect. The 0° shale was sheared along the bedding and thus no en-echelon fractures was formed. The en-echelon fractures inclined to the bedding were formed for the 30°, 45°, 60° and 90° shales, while that formed in 120°, 135° and 150° shales are along the bedding planes. The scale of the en-echelon fractures exhibits significant anisotropy. (3) The en-echelon cracks formed in compression-shear loading are mainly tensile cracks, while the en-echelon fractures are mainly connected by shear cracks. (4) The shear fracture zones are banded with a clear structure when the bedding is not developed. The shear fracture zones gradually become lenticular with increasing number of bedding, and decrease in size and increase in number. The shear fracture zone is a multi-branched complex band when the beddings are developed to a certain degree.
- 1
-
Research on the shear mechanical properties of anchor cable with C-shaped tube under different preloads
Abstract:
Utilizing a frictionless double shear test setup between the nodal surfaces, shear test studies were carried out on anchor cables and the new type of anchor cable with C-shaped tube, and the effect of preload on the shear performance of the two structures was analyzed. The test results show that the negative effect of preload on the anchor cable is greater than that of the ACC structure. As the preload force was increased from 100 kN to 300 kN, the shear load capacity of the anchor cable was reduced by a maximum of 14.82%, while the ACC structure was reduced by only 6.53%. Meanwhile, finite element simulation is utilized to deepen the study of the shear deformation characteristics of the ACC structure. The results show that the higher the preload, the lower the ACC peak shear load and breaking displacement, the higher the flexural stiffness of the structure, the earlier the strength of the specimen is mobilized and the faster the specimen fails locally. The ACC breaking displacement is maximum at a preload force of 100 kN, which is due to the fact that for the same shear displacement, a lower preload force will result in less tensile deformation at the shear plane location of the structure, and will also result in a larger bending angle of the structure at the shear plane location.
- 1
-
Strength design and application of roof backfill bearing layer and capping layer in downward driftZHENG Cong1, QIAO Dengpan1, LONG Gan1, LI Zibing1, LI Yongming2, LIAN Baidong3, YANG Tianyu1
Abstract:
In the downward drift filling mining method, the roof filling body is usually divided into bearing layer and capping layer, and its strength is the key factor to ensure the roof stability in the process of drift mining. The stress of the downward rectangular approach is analyzed. Considering that the filling body is the surrounding rock on both sides of the approach, the strength of the bearing layer and the capping layer of the access filling body are designed respectively by combining the complex function rectangular orifice stress solution method, the uniaxial compression deformation test and the shear strength test of the filling body, and the rationality of the design strength is verified by the industrial application in the mine site. The results show that when the lateral pressure coefficient of the filling body is 0.29, the aspect ratio of the rectangular roadway is 1.0, the tensile strength of the bearing layer σt=0.26 MPa and the compressive strength of the capping layer σc=2.88 MPa are designed with the safety factor f=1.5, and there is no lateral collapse of the filling body and roof caving during the mining and filling process of the underground stope, and the design strength can meet the requirements of safe operation on site.
- 1
-
Structural Design and Performance Analysis of Bend-Resistant Directional Drill Pipe Joints
Abstract:
In multi-branch hole drilling operations, directional drill pipe joints frequently fail due to repeated bending. This study utilizes finite element analysis to simulate the three-dimensional mechanical behavior of directional drill pipe joints under bending loads, clarifying the stress distribution patterns. Based on this, a new type of bend-resistant drill pipe joint structure is proposed, and its differences in bending and bending resistance performance compared to conventional joints are analyzed using finite element models. The results show that, at the same bending angle, the maximum stress of the new joint is reduced by more than 27%; under a 100KN lateral force, its maximum stress decreases by more than 99MPa. Detailed stress distribution data at the joint location were obtained through drill pipe bending experiments, with an error between experimental and simulation data of less than 13%, validating the effectiveness of the numerical simulation method. The research indicates that the proposed new bend-resistant joint outperforms conventional joints in terms of bending performance and resistance to lateral loads. The findings of this study provide an optimized design solution for directional drill pipe joints, which has significant application value in improving connection reliability and reducing the risk of construction failures.
- 1
-
Abstract:
In the mine hoisting system, the crown wheel device serves as a pivotal component, responsible for altering the direction of the steel wire rope, providing support, and transmitting power. Its performance directly determines both the safety and efficacy of the hoisting machinery. As mining depths and outputs progressively escalate, the demand to augment both the speed and load-bearing capacity of the lifting system intensifies. This, in turn, imposes more stringent expectations on the performance and reliability of the mine hoist crown wheel apparatus. To fulfill the requirements for high-speed and heavy-load operations, it is imperative to assess whether the material and structure of the head wheel device are capable of supporting the necessary bearing capacity. The structure of the head pulley device of JKMD-6×8 (IV) 1547.5-meter mine hoist was designed, and subsequently, a finite element simulation model was constructed for the head pulley device. Based on the impact limit theory, the optimal starting, running and braking motion plans were determined. A comprehensive plan for calculating kinematic parameters throughout the lifting process was devised. Subsequently, leveraging these computational results, the transient dynamic characteristics of the head pulley device were thoroughly analyzed. The simulation outcomes demonstrate that the engineered head wheel device not only fulfills the strength requirements but also operates seamlessly under the specified conditions. The results reveal that the weld seam between the spokes and the rim and the hub is subjected to the greatest stress and stress concentration occurs. When the mine lifting system undergoes frequent starts and stops, this area is particularly prone to distortion or fracture. In response, structural improvements have been implemented to mitigate stress concentration and bolster the bearing capacity of the crown wheel, thus ensuring the stable and reliable operation of the lifting system.
- 1
Study on the Performance of Carbide Slag and Silica Fume Synergistically Improving Hemihydrate Phosphogypsum Backfill Ccementing MaterialAbstract:
To address the issues of poor short setting time, water resistance, and inadequate strength when β-hemihydrate phosphogypsum (β-HPG) is used as backfill cementing materials, this study introduced two industrial solid wastes: carbide slag and silica fume. The impacts of these additives on the workability, water resistance, and strength of β-HPG were analyzed. Furthermore, the micromorphology and pore structure of the modified β-HPG were investigated, and the environmental behavior, costs, and carbon emissions of the modified β-HPG were evaluated. The results indicate that the combined use of carbide slag and silica fume significantly extended the setting time of β-HPG and enhanced its fluidity. Following modification, the compressive strength of β-HPG was substantially increased, reaching a 28-day strength value of 36.6MPa, with a reduced water absorption rate of 2.7% and an elevated softening coefficient of 0.885. The incorporation of both silica fume and carbide slag improved the micromorphology and pore structure of β-HPG, and the formation of calcium silicate hydrate, a hydraulic hydration product, enhanced the compactness of β-HPG. Carbide slag and silica fume effectively neutralize residual acids in the β-HPG and immobilize phosphorus and heavy metal elements within the hardened body. When carbide slag was added at a rate of 10% and silica fume at a rate of 15%-20%, the β-HPG cementing material exhibited favorable economic and environmental benefits.
- 1
Backfill body strength prediction model based on stope structural parameters and parameters optimizaitonAbstract:
The filling strength design is an important link and safety guarantee in the production of backfill mines. Filling strength design is often determined through indoor proportioning experiments or engineering experience methods. The influence of structural parameters such as stope height, stope length and stope span on the required backfill strength is often ignored. To solve the problem, taking a copper mine as the background, based on the Li-Li strength analytical model, and calculates the theoretical strength values of the one-step stope and the two-step stope under different structural parameters through orthogonal experiments. The study found that the significance order of stope structural parameters affecting the theoretical strength of the backfill body is: stope height > stope span > stope length. The filling strength prediction models based on structural parameters were constructed for one-step and two-step stopes , respectively. Finally, based on the prediction model and existing filling technology, the stope structure parameters were reversely optimized. The recommended optimal stope height range is 5m~25m, the optimal stope span range is 9m~12.5m, and the optimal stope length range is 80m~120m. It is also used to guide production and strictly control stope specifications to avoid over-excavation and under-excavation. The collapse phenomenon caused by unreasonable stope structure and insufficient filling body strength on site has basically disappeared. This study provides engineering reference for the theoretical strength prediction of backfill body and the optimization of stope structural parameters in backfill mines.
- 1
Thickness Optimization of Horizontal Isolated Pillar in Vertical Zonal Mining from Open-Pit to UndergroundAbstract:
In order to achieve the mining production capacity of 15000kt/a in mining transition open-pit to underground mining project in Sijiaying Iron Mine, the longitudinal zonal stoping method is adopted, and horizontal isolated pillars are required between the upper and lower mining areas. For improving the overall stability of mining area, FLAC3D numerical simulation method was used to assess the evolution characteristics of stress field in 5 kinds of horizontal isolated pillars with different thickness, the development law of deformation and failure, and the influence law of the thickness of isolated pillars on the surface settlement and deformation of open pit. Finally, the safety thickness of horizontal isolated pillars in this mine was determined to be 18m. The results show that: (1) with the increase of pillar thickness, the concentrated stress in pillar decreases significantly, the distribution of maximum principal stress tends to be uniform, and the distribution range of tensile stress decreases significantly, mainly in the stope part of the mining panel; (2) In the horizontal isolated pillar, the displacement presents an obvious nonlinear decreasing change law with the increase of the pillar thickness. The larger displacement occurs at the position where the pillar is close to the hanging wall of the orebody. When the pillar thickness is 18m, the maximum displacement is 36.2mm. (3) The volume of the plastic zone in the isolated pillar shows a nonlinear decreasing trend with the increase of the thickness. When the thickness of the pillar is 16m, the plastic zone is no longer connected, while when the thickness of the pillar reaches 18m, only a small amount of plastic failure occurs locally, and the isolated pillar is in a safe state. (4) The deformation and settlement amount of the open pit surface gradually decreases with the increase of the thickness of the isolated pillar, and the position where the maximum displacement occurs is the same as the one where the maximum displacement occurs in the isolated pillar. When the thickness of the pillar is 18m, the surface settlement amount of the open pit is 10.8mm, indicating good stability.
- 1
Research on Borehole Layout for Open-pit Mine Based on UAV Laser Scanning TechnologyAbstract:
With the continuous evolution of mining technology, increasingly stringent requirements for precision and efficiency in blasting operations have emerged. Traditional RTK point staking methods for borehole positioning are characterized by low efficiency and high labor costs, making them unsuitable for large-scale borehole layout. The application of UAV-based LiDAR technology in borehole positioning for open-pit mines is analyzed, and a comparison with traditional RTK methods is conducted in terms of operational efficiency, environmental adaptability, and economic feasibility. Field tests and data analysis indicate that positioning errors are reduced from 20 cm to 0.2 cm through UAV-based LiDAR technology. Additionally, field operation time is shortened from 180 minutes to 30 minutes, and borehole coverage capacity is increased by 185.6% compared to RTK point staking methods. In terms of operational costs, the cumulative cost over 10 years is reduced by approximately 1.77125 million RMB when compared to RTK methods. Furthermore, precise coordinates are provided for the collaborative operation of intelligent drilling rigs and borehole inspection robots, facilitating intelligent blasting and offering critical technical support for the intelligentization of mining operations. The application prospects are considered extensive.
- 1
Study on the Mechanism of Heavy Metal Pollution in Groundwater Caused by Paste Backfill in a Lead-Zinc MineAbstract:
To investigate the impact of paste backfill on groundwater in a lead-zinc mine, soaking and leaching experiments were conducted to explore the effects of solid concentration and cement-to-tailings ratio on the pH and electrical conductivity of the soaking and leaching solutions. The results showed that both the pH and electrical conductivity of the soaking and leaching solutions exhibited a trend of initially increasing and then decreasing over time. When the cement-to-tailings ratios were 1:4, 1:10, and 1:20, the pH of the soaking solution decreased by 0.50, 0.66, and 1.77, respectively, on day 48 compared to day 1, with the maximum electrical conductivity values reaching 2050 μS/cm, 1910 μS/cm, and 1220 μS/cm, respectively. The pH of the leaching solution decreased at rates of 0.11 d?1, 0.12 d?1, and 0.18 d?1 during the first 14 days, and 0.08 d?1, 0.06 d?1, and 0.03 d?1 during the following 14 days, respectively. This indicates that This indicates that as the cement-to-tailings ratio increases, the pH of the soaking solution decreases less, the maximum electrical conductivity increases, and the pH decline rate of the leaching solution slows in the early stage but increases in the later stage. The solid concentration had little effect on the pH and electrical conductivity changes of the soaking and leaching solutions over time. The release behavior of harmful ions is primarily governed by the adsorption of hydration products and the pore structure, with hydration reactions dominating in the early stage and carbonation reactions playing a more significant role in the later stage. The study results indicate that the concentration of heavy metal ions released from the backfill is far below the limits specified by relevant national standards, suggesting that the paste backfill has good environmental protection performance.
- 1
Research on Intelligent Mineral Matching Technology in Mines Based on Improved White Whale Optimization AlgorithmAbstract:
To enhance the efficiency of mine blending and resource utilization, this study applies intelligent optimization techniques to mine blending and proposes an improved beluga whale optimization algorithm (IBWO) based on the beluga whale optimization (BWO) algorithm. The IBWO integrates chaotic mapping and Levy flight strategies. Its performance was validated through an actual mine blending case study. The results indicate that, compared to five other algorithms, the IBWO demonstrates significant advantages in convergence speed and global optimal solution searching capability, achieving a convergence speed improvement of 31.2% to 165.9%. In numerical simulations for mine blending optimization, the IBWO achieved an average profit of 250,600 RMB after 31 iterations, representing a profit increase of 14.69% to 17.93%. This research provides a novel approach for mine blending optimization and is expected to offer a theoretical foundation for improving resource utilization efficiency and economic benefits in mining production.
- 1
Y1=1.65+0.81A+0.085B+0.045AB-0.285A2-0.05B2 R2=0.9994Y2=3.14+1.18A+0.23B+0.12AB-0.477A2-0.19B2 R2=0.9986Abstract:
Taking the mine's ultra-fine tailings as the filling test research object, the optimal mass concentration of mortar and the factors affecting the strength of the filling test block were explored through slump, strength ratio test and response surface analysis method, and the strength of the test block was predicted through BP and NGO-BP neural network model and compared with the real test strength. The results showed that: The optimal mass concentration for pump pressure transportation is 72%~74%, and the optimal mass concentration for gravity transportation is 68%~72%. A regression model was established with the strength of the filling body at 3, 7 and 28 days as the response value. The results show that the influence of the cement-sand ratio is the most significant. The larger the cement-sand ratio, the greater the strength of the test block; The 28-day NGO-BP neural network prediction was optimized by 47%, 70%, 96%, 66%, and 26% compared with the BP neural network's mean square error (MSE), root mean square error (RMSE), mean relative percentage error (MAPE), and absolute coefficient (R2), respectively, indicating that the NGO-BP neural network model is greatly improved compared with the BP neural network model, providing a new idea for optimizing the filling ratio.
- 1
Study on Dynamic Monitoring of Open-pit Mines Cross-border Mining based on High-resolution Remote Sensing ImagesAbstract:
Mineral resources are an important material foundation for human survival and development. China"s open-pit mines have serious cross-border mining, and it is of great significance to strengthen the research on regulatory technology for cross-border mining of open-pit mines. High resolution remote sensing technology, which has high resolution, strong reliability, and fast and economical monitoring methods, is very suitable for dynamic monitoring of open-pit mining activities. Three periods of high-resolution remote sensing images were selected to extract the information of changes in the patterns of open-pit mining in Xiangtan City"s provincial and municipal certified open-pit mines, and to carry out remote sensing dynamic monitoring research on open-pit mining activities. Established a remote sensing interpretation marker library for the development of open-pit mines in the research area; Explored a relatively complete set of dynamic monitoring technology methods for open-pit mine boundary mining.The accuracy verification accuracy of suspected cross-border mining and mining development accounts for 100% and 90.3% of the map spot accuracy, respectively; In 2016-2020, the number of mines, map spots, and total area of open-pit mines in Xiangtan City that were issued with certificates at the provincial and municipal levels showed an overall decreasing trend. The research results indicate that high-resolution remote sensing technology has strong practicality, high accuracy, and can effectively monitor the dynamic changes of cross-border mining in open-pit mines. The research results can provide technical support for the dynamic monitoring of cross-border mining in Xiangtan City and also provide reference for other areas in Hunan Province.
- 1
Research on intelligent incremental methods for image samples in intelligent recognition of rock mineralsAbstract:
Intelligent recognition of rock and mineral technology is crucial for mineral exploration and environmental protection in the fields of geology and mineralogy. However, the scarcity of samples seriously restricts the development of deep learning models. Based on this, an improved deep convolutional generative adversarial network (Deep) is proposed The rock mineral image sample intelligent incremental method of Convolutional Generative Adversarial Networks (DCGAN) utilizes self-attention mechanism to improve the generation ability of the generative network, and uses Wasserstein distance to optimize the loss function of the model. At the same time, it extends the overall architecture of the network to generate large-scale mineral images. The experimental results show that the improved method of this model has achieved significant results in generating the diversity and large size of rock minerals. The generated results are superior to the original model in evaluation indicators such as peak signal-to-noise ratio (PSNR), Fréchet Inception Distance (FID), and structural similarity (SSIM). The questionnaire survey further confirms the superiority of the improved model in image diversity and realism. By generating new identification data, the diversity and richness of rock and mineral samples have been enhanced, effectively solving the problem of sample scarcity and laying a solid foundation for the intelligent development and practical application of rock and mineral image generation.
- 1
Study on the safe thickness of pot-bottom type isolation pillars in transition areas of different mining processesAbstract:
The form and thickness of isolation pillars during the caving-to-filling process are crucial to the safety and efficiency of mine production. Taking the mine production of a gold mine in the transition stage from caving to filling as the background, the safe thickness and stability of the pot-bottom type isolation pillar were analyzed by combining theoretical calculation and FLAC3D numerical simulation. The results showed that : The theoretical thickness of the I-shaped isolation pillar at the bottom of the joint pillar is 30m, while the horizontal thickness of the pot-bottom isolation pillar is 15m. Through the calculation of the maximum unbalanced force and excavation convergence balance cost, it was found that the ground pressure activity during the caving-to-filling mining process was generally stable, and the isolation pillars effectively controlled the ground pressure risk.The isolation pillar did not exceed the tensile stress limit during the mining process, indicating that it has good self-bearing capacity. The application of the filling method significantly slowed down the settlement rate of the ore body and enhanced the stability of the stope. During the mining process, the isolation pillars did not undergo plastic failure and penetration, ensuring the safety of simultaneous mining. However, we need to be vigilant against local plastic failure of the side wall filling and potential landslide risks.
- 1
Research on key Parameters and Application of High Concentration Continuous Filling Process for Tailings of Shizhuyuan Polymetallic MineCHEN Guohui1, ZHENG Bokun2,3,SHI Yong2,3, YUAN Ziqi2Abstract:
Aiming at the problems of large ore depletion rate and serious surface subsidence in Shizhuyuan Polymetallic Mine, which was originally mined by the avalanche method, the mine proposes to switch to the filling method. Tailings physical and chemical properties test, static-dynamic flocculation and settlement test, combined with the actual production capacity of the mine, to determine the optimal tailings thickening parameters and thickening machine size; reference to the PSO-SVM algorithm, the establishment of the sand release stability prediction model, and get the optimal sand release process parameters. The results show that: the optimal type of flocculant is CKYZ-24S#, its optimal mixing amount is 30g/t, the optimal quality concentration of the whole tailing sand feed is 12.5%, and the optimal feeding rate of the tailing sand is 0.744t/(m2?h); the diameter of the thickener is determined to be D=12m, and its height is H=20m; the height of the tailing sand mud layer is 15.2m, and the time of thickening is 3.
- 1
Yan Guangli. Research on Game and Strategy of Environmental Remediation Evolution in Ion-Type Rare Earth Mines[D]. Beijing: Beijing University of Science and Technology, 2020.
Abstract:
Mine environmental treatment project is an important link to promote green development, and it is very important to study how to game and coordinate the relevant stakeholders to promote the green development of mines. First of all, based on the perspective of stakeholders of mine environmental treatment, with the help of evolutionary game tools of limited rationality, a tripartite evolutionary game model of mine environmental treatment is constructed among local governments, mining enterprises and local residents. Secondly, the actual operation data of mining enterprises are introduced, and the long-term dynamic game process of stakeholders is modeled and analyzed in combination with system dynamics, so as to study the influencing factors of the behavior strategy of the main body of mining environmental treatment. Research shows: The five influencing factors of government subsidies for enterprises, government penalties for enterprises, corporate public relations fees, additional cost-benefit differences for e
- 1
Research and Application of Automatic Drill Pipe Conveying Technology for Raise Boring MachineAbstract:
In view of the problems of low degree of automation, high labor intensity, low efficiency and high safety risk in the traditional raise boring machine construction, which relies on manual auxiliary operation to complete the handling and conveying of drill pipes, in order to meet the requirements of unmanned construction in a single shift of raise boring machine, the basic idea of automatic conveying of drill pipes technology is determined, and the automation solution of "drill pipe conveying - drill pipe grab - drill pipe transfer - drill pipe loading and unloading" is proposed. First of all, through the analysis of the process of the automatic conveying of drill pipe by the raise boring machine, the functional requirements and motion characteristics of the automatic conveying of drill pipe are defined; Secondly, the automatic drill pipe conveying device and hydraulic manipulator were developed, and the finite element analysis software was used for simulation and optimization design; Thirdly, the automatic conveying hydraulic control system and control logic are researched, and the feasibility of this method is effectively verified by field application. The production practice shows that the automatic drill pipe conveying technology of raise boring machine has good positioning accuracy, motion performance and stability, and can accurately and quickly convey, grab, transport and store drill pipes, which can meet the practical engineering application of unmanned, safe and efficient construction of raise boring machine in a single shift.
- 1
Evaluation of emergency management capability for rockburst in deep mine tunnels based on two-tuple linguisticAbstract:
Considering the fuzziness and uncertainty of emergency management capability evaluation for rock burst in deep mine tunnels, a comprehensive decision analysis model based on combination weighting two-tuple linguistic was established. Firstly, based on the PPRR theory, 18 influencing factors were selected to construct a multi-level evaluation system for rock burst emergency management capabilities; Then, the interval analytic hierarchy process and two-tuple linguistic entropy weight method are combined to obtain the comprehensive weights of indicators. Based on the two-tuple linguistic method, the language information of decision-makers is processed reasonably. By calculating the comprehensive evaluation value, the emergency management level is comprehensively judged; Finally, taking a certain copper iron mine as an example, the established evaluation model is applied to conduct research on the level evaluation of rock burst emergency management capability. The results show that the emergency management capability of the mine for rock burst is at a "good" level, which is completely consistent with the conclusions of expert on-site research. Through examples, the adaptability of the combination weighting two-tuple linguistic model in the evaluation of rock burst emergency management capability is demonstrated, which can provide new ideas for the evaluation of rock burst emergency management capability..
- 1
Stability analysis and optimization of structural parameters of a crushed thick and large ore body in a mineAbstract:
Large and fragmented ore bodies are widely distributed in domestic mines, and the safe and efficient recovery of these resources significantly impacts the economic development of the mines. In the context of mining a specific large and fragmented ore body, ensuring the stability of the mining area is fundamental for supporting efficient and safe extraction. Therefore, based on this ore body, structural parameters of the mining area during the downward wall-filling method are optimized. The study investigates the effects of roadway dimensions, roadway layout, and filling frequency on the stability of the mining area. The findings indicate that the principal stress is nearly uniformly distributed near the roof of the excavated area, with the minimum principal stress appearing as tensile stress in the upper plate and nearby areas, while the maximum principal stress is consistently compressive. The maximum settlement occurs at the center of the mining area roof, with significant settlement on the upper plate and no settlement on the lower plate, only slight bulging. It is recommended that the roadway dimensions be 3.0×3.0m, with a vertical cross "Ⅹ" layout for the roadways and a single full-height backfill. The application of the optimized parameters provides technical support for resource recovery in this mine, yielding significant economic benefits and laying a foundation for future mining operations.
- 1
Table 2 The result of closed-circuit test of hematite reverse flotation /%Abstract:
This study focused on the effect of the preparation conditions of causticized starch on the densification effect of hematite reverse flotation in a typical Anshan-type hematite in Hebei Province. The optimal combination of key preparation parameters—including causticizing ratio, temperature, and time—was determined through single-factor variable experiments and closed-circuit process tests. The results showed that under the optimal conditions of a causticizing ratio of 8:100, a causticizing temperature of 90°C, and a causticizing time of 30 minutes, the selective inhibition performance of causticized starch was significantly improved. In the closed-circuit test, the iron concentrate and tailings grade were 67.02% and 20.65%, respectively, with an iron recovery of 87.63%. Fourier-transform infrared spectroscopy and Zeta potential analysis revealed the mechanism of changes in the molecular structure and adsorption performance of causticized starch. The results confirmed that after causticizing treatment, the hydroxyl and carboxyl groups of starch were effectively exposed, enhancing the depressant"s chemical adsorption capacity on the hematite surface, thereby achieving selective hematite depression. This study provides a novel approach to the green and sustainable development of densification processes in hematite reverse flotation.
- 1
Optimal selection of mining and transportation equipment schemes for potassium salt mines based on interval analytic hierarchy process and fuzzy matter element analysisAbstract:
The reasonable selection of mining and transportation equipment for potassium salt mines is related to the realization of production capacity and the control of mining costs. In order to comprehensively and scientifically optimize the equipment scheme for potassium salt mine mining, the interval analytic hierarchy process was used to construct the interval judgment matrix of the optimization indicators, and the weights of the optimization indicators were analyzed and calculated based on this. A multi-objective optimization model for potassium salt mining and transportation equipment schemes was constructed using fuzzy matter element analysis. The comprehensive relative membership degree of each alternative potassium salt mining and transportation equipment scheme was analyzed and calculated. Through calculation, the comprehensive relative membership degree of the scheme of continuous mining machine+diesel shuttle truck was 0.7579, which was the highest among the four schemes. The mining cost of this scheme was only 4.2 yuan/ton, the safety performance was 90%, and the pollutant emissions were only 81%. The mining cost, safety, and environmental protection were all better than other schemes. Therefore, this scheme was selected as the optimal scheme. Through examples, it has been proven that the interval analytic hierarchy process and fuzzy matter element analysis can provide more scientific and practical optimization of equipment schemes for potassium salt mining, thereby providing guidance and assistance for potassium salt enterprises to improve economic and comprehensive benefits.
- 1
Experimental Study on the Performance of Solid Waste-based Phase Change Regenerative BackfillsAbstract:
In order to solve the problems of geothermal disaster in deep mine and the influence of construction waste accumulation on natural environment, a new porous material, waste foamed concrete, was used as supporting material and solid paraffin wax to prepare phase change material. It is used to replace part of the coal gangue content in different proportions ( referred to as the substitution ratio of phase change heat storage material ) as aggregate to prepare phase change heat storage filling body with cement and fly ash. The microscopic properties of phase change thermal storage materials and phase change thermal storage filling bodies were studied by scanning electron microscopy. The phase change thermal storage filling bodies were tested by Shimadzu electronic universal material testing machine and thermal conductivity meter to explore the mechanical and thermal properties of filling bodies under different phase change thermal storage materials. The results show that the phase change storage backfill prepared by PCM as filling aggregate has good microstructure and uniform distribution, and excellent setting effect, and can maintain stable shape at high temperature. The uniaxial compressive strength of the backfill gradually decreases to 3.28 MPa, with a decrease of 34.3%, with the increase of the substitution ratio of phase change heat storage material to 20 %. The thermal conductivity and heat storage coefficient decreased, and the specific heat capacity increased from 1.04 kJ/(kg·K) to 1.38 kJ/(kg·K). In summary, the phase change heat storage filling body prepared by the experiment has a certain thermal conductivity / heat storage capacity under the requirement of meeting the compressive strength of the phase change heat storage filling body.
- 1
Influences of the scale of the brow line damage on drawing effect in the mining roadway using the caving mining methodAbstract:
To investigate the influence of the brow line damage scale on drawing effect, based on the theory of stochastic medium theory and physical similarity principles, the physical similarity experimental approach was adopted to establish a single stage end drawing model. Drawing experiments under brow line damage were carried out from two scales of width and height. The morphology of the draw body under different experimental parameters was delineated through the method of hole, the ore loss and dilution indicators were calculated. The results indicate that under the same cut-off conditions, with the increase in the width of the brow line damage, the scale of the draw body in the direction of the mining roadway increases, while there are no significant changes in the width of the draw body in the perpendicular mining roadway. For every 0.5 m increase in the width of brow line damage, the proportion of waste rock mixed from the front increases by 1.2%, the proportion of waste rock mixed from the top decreases by 0.5%, and the ore recovery ratio decreases by 0.6%. As the height of the brow line damage increases, the development of the draw body is mainly in the vertical direction, and the draw body becomes more slender. For every 0.5 m increase in the height of brow line damage, the proportion of waste rock mixed from the front decreases by 0.2%, the proportion of waste rock mixed from the top increases by 3.9%, and the ore recovery ratio decreases by 5.0%. In terms of the impact on drawing effect, the height of the brow line damage is significantly more important than the width of the damage. Therefore, in engineering practice, priority should be given to implementing measures that prevent and mitigate damage to the height of the brow line.
- 1
Research on the secondary support scheme of arched roadway based on plastic zone controlAbstract:
Considering the characteristics of the Baiyin Haer mine roadway, which has hard rock mass, severe alteration, and extremely poor stability, a secondary support method based on the distribution of the plastic zone was proposed. For fractured surrounding rock, the physical and mechanical parameters of the rock mass were obtained through point load tests and relevant shaft construction data of the Baiyin Haer mine. Using three equivalent radius methods along with Fenner's formula and the D-P criterion formula, the plastic zone range of the arched roadway was calculated. Additionally, the Kastner approximate solution for the plastic zone boundary of a circular hole in a non-uniform stress field was computed. Numerical simulation was employed to obtain the displacement, stress, plastic zone distribution, and the original support effect after excavation. Based on the plastic zone distribution effect of the original support, secondary support was focused on the roof, roof corners, and floor of the roadway. The results indicate that the equivalent radius method of the rectangular circumscribed circle and the D-P criterion are more suitable for calculating the plastic zone of the Baiyin Haer mine roadway. Combined with numerical simulation, it is found that gold-bearing altered rock is mostly distributed in the roof corner area. After secondary support based on the plastic zone distribution of the arched roadway, the deformation of the surrounding rock in the roof and floor of the arched roadway significantly reduced. The roof displacement decreased from the original 23 mm to 8 mm, and the floor displacement reduced to about 10 mm. The stress concentration on the roof decreased, and the plastic zone range significantly reduced, which helps prevent shear failure of the surrounding rock in the arched roadway.
- 1
Analysis on the stability and influencing factors of the adjacent shaft of the caving and filling mining areaAbstract:
The stability of the mine shaft is crucial to the safety and efficiency of the mining process. Taking the damage to the wellbore adjacent to the caving stope and the filling stope as the background, a three-dimensional numerical model of three stopes including the bottom column caving method, the bottom column caving method and the approach filling method was constructed, and the impact of different stopes on the wellbore was analyzed. impact on stability. Research results show that the main cause of shaft damage is the superimposed effect of the disadvantageous geological conditions of the rock mass in the ore-penetrating section and mining disturbance. The order of influence of stope disturbance caused by different mining methods on the maximum deformation value of the wellbore is: stope with approach filling method > stope with caving method > stope with caving method without bottom column. Especially when simultaneous mining is carried out in caving stopes, the superposition of disturbance effects makes the deformation of the wellbore more significant. On the basis of comprehensive consideration of the existing engineering conditions, a top-down curtain grouting reinforcement plan was designed to address the geological and mining risks that may be faced during the mining of the ore body outside the +710m to +830m depth security pillar. This solution provides effective technical support to ensure the safe mining of Shaft 1# in the subsequent mining process.
- 1
Research on Safety Evaluation Model of Coal Mine Electromechanical System Based on G1-FDEMATEL Interval ApproximationAbstract:
In response to the complexity and ambiguity of safety assessment for coal mine electromechanical systems, interval approximation theory is introduced to improve the objectivity and reliability of assessment results. A comprehensive safety evaluation model for coal mine electromechanical systems based on G1-FDEMATEL-interval approximation is established. Firstly, based on the theory of accident causation intersection, 17 indicators were selected from the four dimensions of human, machine, management, and environment to construct an evaluation system; Secondly, the G1-FDEMATEL method is coupled to obtain the comprehensive weights of indicators. Based on the principle of interval approximation, the interval estimation method is used to determine the evaluation data of indicators, which compensates for the drawbacks of discontinuous point estimation values and missing information in traditional models. By calculating the comprehensive distance, the safety level of coal mine electromechanical systems is determined; Finally, taking 5 coal mines as examples, the G1-FDEMATEL interval approximation model is applied to analyze the safety status of the electromechanical system, and the evaluation results are compared with the VIKOR and TOPSIS models. The results showed that the safety level of the electromechanical systems in all five coal mines was "relatively safe", consistent with the conclusions of on-site research, which verified the adaptability and scientificity of the model and provided theoretical support for preventing and handling electromechanical system safety accidents.
- 1
A Study on Rock Compressive Strength Prediction Model Based on Newton-Raphson Optimized CNN-LSTMAbstract:
In order to improve the prediction efficiency and accuracy of uniaxial compressive strength (UCS) of rocks, a combined model based on convolutional neural network (CNN) and long short-term memory network (LSTM) is proposed and optimized using Newton Raphson based optimization (NRBO). Conduct extensive research and collect relevant experimental data, including point load strength, Schmidt hammer rebound number, porosity, and longitudinal wave velocity. After data preprocessing, 381 sets of data were retained and visualized. To evaluate the performance of the model, mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R 2) were used. Introduce random forest model, BP neural network model, and CNN-LSTM model for comparison. The results showed that the NRBO-CNN-LSTM model was superior to other models, with a coefficient of determination R2 of 0.98, a mean square error RMSE of 6.27, and an average relative error MAE of 4.82; This indicates that the model has good fitting ability and generalization performance, and can predict the uniaxial compressive strength of rocks with higher accuracy.
- 1
Optimal selection of tailings thickening devices based on the AHP-TOPSIS evaluation modelAbstract:
To address the challenges of selecting suitable tailings thickening devices for domestic mines due to the diversity of available options, a tailings thickening device optimization method based on the AHP-TOPSIS evaluation model is proposed. This method considers 13 evaluation criteria from aspects such as economics, site conditions, and technology, and involves expert scoring to comprehensively assess and optimize three types of thickening devices: vertical sand silo, deep cone thickener, and paste storage thickener. Through the computational analysis of these three devices, the comprehensive advantages of each option were found to be 49.51%, 17.42%, and 80.11%, respectively. Option 3 (paste storage thickener) was identified as the best solution. Therefore, the paste storage thickener was selected as the tailings thickening device for the backfilling system of a polymetallic mine in Hunan. The results align with the actual field application, where the backfilling system uses a paste storage thickener with a single unit handling tailings at a rate of ≥100 t/h and a tailings storage capacity of ≥1600 t. The thickener achieves a maximum underflow density of 74%, with good backfilling performance. This demonstrates that the evaluation model is valuable for selecting tailings thickening devices and provides a reference for optimizing tailings thickening devices in backfilling systems of similar mines.
- 1
Reutilization mode selection strategy of abandoned mine based on risk management perspectiveAbstract:
Abandoned mine not only contains a large number of available resources, but also has many risk factors. Therefore, how to scientifically decide the reuse mode and effectively manage many risks is an important prerequisite for the implementation of industrialization. Based on this, from the perspective of mine closure risk management, this paper constructed an abandoned mine risk system including technical risk, safety risk, environmental risk, community risk, legal risk and financial risk, and used the hazardous operation conditions analysis method for the risk evaluation. Secondly, this paper puts forward the best reuse mode of abandoned mine by using expert group decision making and TOPSIS method. Finally, taking Muchengjian Coal Mine in West Beijing mining area as an example, the results showed that this risk management method can help optimize the reuse mode of abandoned mines and effectively reduce the negative effect of mine closure.
- 1
Simulation study on the influence of ore moisture content on the crushing characteristics of high pressure roller grindingAbstract:
The optimization of the crushing effect of high pressure roller grinding is of crucial importance in relation to the enhancement of ore processing efficiency, the reduction of energy consumption, and the elevation of product quality. Ore moisture content represents one of the significant factors exerting an impact on the crushing performance of high-pressure rollers. In order to investigate the influence pattern of ore moisture content on the crushing effect of high-pressure rollers, with the magnetite ore from eastern Hebei selected as the research specimen, the moisture content of the materials was denoted by setting the particle surface energy. In combination with SolidWorks modeling and EDEM simulation, the interaction between high-pressure rollers and particles under diverse feed moisture content conditions was simulated. In light of the simulation outcomes, open-circuit tests of high-pressure rollers under different feed moisture content conditions were conducted for verification. It was ascertained that as the feed moisture content augmented from 0.11% to 6%, the crushing effect of high-pressure rollers initially ameliorated and subsequently deteriorated, which was in accord with the regularity of the simulation results. The results demonstrate that when the feed moisture content lies within the range of 1.5% - 4.5%, the particle size of the product subsequent to crushing by the high-pressure roller mill is finer and the crushing effect is more favorable.
- 1
Study on the effect of temperature cyclic impact on the geometrical distribution characteristics of coal rock pore and fracture spaceAbstract:
Recognizing the geometric characteristics of coal rock pores and fractures is crucial for controlling the directional expansion of these features and improving permeability in coal reservoirs. To study the evolution of pore and fracture distribution under temperature cycling, we performed impact experiments on anthracite coal and sandstone at high (200°C) and low (-196°C) temperatures, with cycles of 0, 1, 5, 10, and 15 repetitions. Ultrasonic speed measurement and industrial micro-CT were used to analyze changes in ultrasonic longitudinal wave velocity and pore characteristics such as equivalent diameter, openness, and tilt angle. The results help explain the influence of temperature cycling on pore fractures. The results show that: (1) The longitudinal wave velocity of anthracite decreases exponentially with more cycles, with the greatest reduction occurring after the first cycle. Sandstone, on the other hand, shows a logarithmic decrease, with the greatest change at the fifth cycle. (2) The openness of pore fractures correlates linearly with equivalent diameter. Overall porosity increases logarithmically with more cycles, and anthracite is more sensitive to temperature changes than sandstone. (3) As cycles increase, the tilt angle of anthracite fractures decreases logarithmically, while that of sandstone increases exponentially. The difference in carbon content and mineral composition explains this opposite trend.
- 1
Research and Application of Borehole Radar DetectionTechnology Based on Electrical Response Characteristics of Surrounding rockAbstract:
The key to prevent water outburst/gusher in coal mine is to clarify the hydraulic relationship between coal measure strata and aquifer and to accurately detect the occurrence of abnormal areas and take preventive measures in time. Based on the geological characteristics of the mining area and the evaluation of water inrush, the experimental system of coal-rock-water coupling occurrence was established to investigate the electric excitation response characteristics and signal attenuation rule of the medium under the magnetic field outside the borehole radar. The results show that the height of the fracture zone of the working face is 58.25 m, which exceeds the height of the water barrier. The working face is threatened by the water of the Changxing Formation aquifer and the goaf, and the risk of water inrush is high. In LCR digital bridge experiment, the dielectric constant of the medium decreases with the increase of frequency. At 100 MHz, the dielectric electrical characteristics and the peak value of Cp-D (capacitance-dissipation coefficient) feature have obvious differences, and the signal transmission is stable. The resolution of borehole radar detection profile is increased at 100 MHz, and the imaging is stable. The low-resistivity anomaly area is mainly the boundary of rock strata and the water-bearing anomaly area of the Changxing Formation limestone, and some fracture zones and fracture zones have been found to contain water. The research results are brought into the pre-engineering consideration, and the results of geophysical exploration are further analyzed from the quantitative point of view, which provides some practical reference for similar geological water exploration work.
- 1
Determination of Safety Pillar Thickness and Prediction of Dangerous Slope in an Open-pit to Underground MineAbstract:
Addressing the determination of the thickness of security pillars in a mine transitioning from open-pit to underground mining, as well as the prediction of hazardous slopes in open-pit areas. A three-dimensional geological modeling and numerical simulation study was conducted on the security pillar thickness, the reliability of mining methods, and the safety factor of slopes after underground mining cessation using Rhino and FLAC3D software. Initially, underground mining methods were selected based on statistical information of the orebody's characteristics. Subsequently, simplified modeling of the mining panels was carried out to determine a relatively conservative thickness of security pillars with an aggressive extraction scheme. Further, detailed modeling was employed to delineate the mining panels and ascertain the reliability of the chosen mining methods. Finally, the strength reduction method was utilized to identify relatively hazardous slopes and determine the safety factor of the open-pit slopes after underground mining cessation. The following conclusions were drawn from the study: a 30m security pillar can ensure safe underground mining production; the overall stability of the mining panels after underground mining cessation indicates the reliability of the selected mining methods; the safety factor of the slopes after underground mining cessation is 4, with relatively hazardous slopes located on the northern slopes in the middle of the final boundary. The findings provide a reference for the selection of parameters for security pillars and mining methods in similar open-pit to underground mine transitions.
- 1
Finite element analysis of a deep-sea microbial sampling device based on a porous step modelAbstract:
Based on the research background of the filter membrane of the microbial sampler, the porous step model is used to simulate the structure of the microbial sampling membrane, and the numerical simulation of the internal flow field of the sampler is carried out through the finite element method. The influence of the fluid inlet velocity parameters on the performance of the deep-sea microbial sampling device is studied from the filter pressure drop, the variation law of the flow velocity and the distribution of the velocity and pressure nephogram of the sampler, so as to determine the optimal parameters of the fluid inlet velocity of the deep-sea microbial sampler. The results show that the pressure drop on both sides of the sampler filter membrane is 36, 82, 139, 207, 288 Pa under the conditions of inlet velocity of 0.1, 0.2, 0.3, 0.4, 0.5 respectively, and the difference of flow velocity on both sides of the sampler filter membrane is 0.05, 0.16, 0.26, 0.34, 0.38 respectively. The pressure drop on both sides of the sampler filtration membrane and the velocity difference between the two sides of the membrane increase with the increase of inlet velocity, and the pressure behind the filtration membrane tends to decrease with the increase of velocity; the filtration performance of the sampler is optimal when the fluid inlet velocity is 0.3 . The numerical simulation results can provide a strong theoretical basis for the study of filtration performance of deep-sea microbial sampling device.
- 1
Analysis and Management of Safety Hazards in Intelligent Mines Based on Multidimensional Data MiningAbstract:
As the construction of intelligent mines progresses, a massive amount of safety hazard data has been accumulated, but the value it contains has not been fully explored. This study uses the historical safety hazard data of a mine in Shandong, China from 2011 to 2020 as the research object, and conducts a comprehensive analysis of the four dimensions of hazard incident types, causes, time, and space. First, a classification model based on a multi-layer perceptron (MLP) is constructed to identify hazard incidents as falling into three major categories: personnel, equipment, and environment. Subsequently, the latent Dirichlet allocation (LDA) topic model is employed to conduct in-depth exploration of equipment-related hazards, innovatively constructing a multi-topic classification model to categorize equipment-related hazards into eight main themes: lighting, transportation, support, electrical, fire protection, blasting, ventilation, and miscellaneous. Furthermore, the Apriori association rule mining algorithm is utilized to analyze the co-occurrence relationships between different hazard characteristics and hazard themes, extracting key information from the unstructured hazard text. The study finds that the lack of equipment management and maintenance is the primary cause of hazard incidents at the mine, with support issues and insufficient lighting being the most significant hazard themes and association rules. Finally, the integration of multi-dimensional analysis and data visualization techniques is employed to conduct an in-depth analysis of the data mining results. Overall, the research findings not only enrich the theoretical foundation of mine safety risk prevention and management but also provide practical references for data value exploration in the construction of intelligent mines, as well as effective approaches for the prevention of mine safety hazards.
- 1
An OPC UA information analysis method Based on multi-hop intelligent retrieval of mining machinery and equipmentAbstract:
In the mining industry, there is a problem of weak data parsing ability for mechanical equipment using OPC UA network communication protocol, which can easily lead to data silos. To address this issue, this paper proposes an OPC UA information parsing method based on multi-hop intelligent retrieval of mining machinery equipment. This method first designs a multi-hop intelligent retrieval model for mining machinery equipment, which integrates GCN and RoBERTa networks to achieve multi-hop inference of equipment entities and infer unknown entity relationships and attributes; On this basis, a system information model architecture based on OPC UA is constructed, which is divided into four sub models: basic functional components, production equipment information model, job progress information model, and safety monitoring information model. The sensor components of mechanical equipment are analyzed through examples; Finally, experimental analysis was conducted on the multi-hop intelligent retrieval model, and the information model of the intelligent system based on OPC UA was tested and verified. The experimental results show that compared to other existing multi-hop intelligent retrieval methods, the method proposed in this paper performs well in short-term contexts the Hit@1 performance indicators have improved by 1.7%, Hit@5 performance indicators have improved by 1.2% in the long-term context, Hit@10 performance indicators are basically unchanged.
- 1
Research on the influence of the cutting parameters of the oscillating cutting disc on the cutting performanceAbstract:
In order to investigate the influence of different cutting parameters of the oscillating disc on the cutting performance, the cutting process of the oscillating disc is simulated by the discrete unit method, and the influence of eccentricity, oscillation frequency, feed rate and cutting depth on the cutting performance is studied. The results show that the average load of rock breaking by oscillating disc is significantly reduced compared with that without oscillating disc, which is specifically shown in the conditions of 60mm/s, 90mm/s, 120mm/s, 150mm/s, 180mm/s, the average load of the disc under oscillating conditions is reduced by 37.37%, 44.19%, 57.47%, 60.32%, and 61.25%, respectively, compared with that without oscillating conditions, 61.25%. Under the same working condition, with the increase of eccentricity, the average load decreases first and then tends to stabilize; with the increase of feed rate, the average load decreases gradually, and the maximum load increases gradually and then tends to stabilize; when the feed rate is less than 90mm/s, the average load increases with the increase of oscillation frequency, and the larger the oscillation frequency is, the smaller the average load is; when the depth of the cut-off is 40mm, both the average and maximum loads are the smallest. Maximum load are the smallest. The eccentricity, oscillation frequency, feed rate and cutting depth of the oscillating disc are optimized at 3mm, 60Hz, 150mm/s and 40mm. The study can provide a reference for determining the cutting parameters of the oscillating chuck to achieve the optimum cutting performance.
- 1
Study on roof caving characteristics and monitoring technology of inclined orebody under slopeAbstract:
The upper orebody of Paishanlou gold mine was mined by open pit method during the period of changing from open pit to underground, the lower ore body is within the National Wilderness Preservation System of Haitang Mountain. The surface is not allowed to collapse. Based on the engineering background of mining the inclined orebody under the slope of Paishanlou gold mine, this paper makes a systematic study on the roof caving characteristics, the stability conditions of caving arch and its control and utilization technology in the mined-out area of the inclined orebody, based on the feature that the inclined orebody of Paishanlou obeys the arch caving model, the mathematical relationship between the critical caving span and caving height of the inclined orebody under the slope is analyzed and established, based on this, a new mining method and related technology for continuous mining of mined-out area and subsequent centralized filling of mined-out area are developed, the field practice shows that the method not only meets the need of surface protection, but also achieves the goal of low-cost, safe and efficient mining.
- 1
Research on the Influence Characteristics of Different Rainfall Conditions on the Stratified Stability of Tailings Dam BodiesAbstract:
As a common waste storage structure in the mining industry, the stability of a tailings dam is directly related to the safety of the surrounding environment and personnel. Rainfall is an important factor affecting the stability of a tailings dam. Especially under different rainfall conditions, the hydrological, mechanical characteristics and deformation characteristics of the tailings dam will change significantly. Through a combination of laboratory experiments and numerical simulations, the laboratory tests determined the mechanical parameters and permeability coefficients of each soil layer of the tailings. Combined with the simulation analysis of the pore water pressure distribution and seepage characteristics under rainfall conditions, the stratified stability of the tailings dam body under different rainfall intensities and durations was studied. The results show that the greater the rainfall intensity and the longer the duration, the deeper and wider the water infiltration depth and range, and the stress distribution inside the dam body changes significantly, thus affecting the overall stability of the dam body. Rainfall will not only increase the surface humidity of the tailings dam and the soil pore water pressure but also weaken the shear force between the stratified structures of the dam body, increasing the risk of landslides. Thus, the instability mechanism of the tailings dam under the action of rainfall is revealed, and targeted strengthening measures are proposed to improve the anti-rainfall ability of the tailings dam. The research results provide an important reference for the design and risk assessment of tailings dams.
- 1
First-principles Calculations For The Flotation Separation of Magnesite and HornblendeAbstract:
Simulating magnesite and hornblende can provide theoretical guidance and support for the flotation separation of the two and the selection of chemicals. The crystal structure, cleavage surface, and the adsorption model with reagents of magnesite and hornblende were simulated by Materials Studio (MS) software based on the first principle of density functional theory. The surface energy, the interaction energy of dodecylamine, the collectors KDLX on the magnesite (104) surface, and the hornblende (110) surface were calculated. The results show that magnesite and hornblende is an insulator with a band gap of 4.920 eV and 3.962 eV, and the optimized crystal structures have better stability. The ammonium hydrogen atoms in the two types of traps interact with the oxygen atoms of the minerals in hydrogen bonding and physical adsorption, and compared with dodecamethylamine, the collectors KDLX has a stronger adsorption capacity for hornblende, which is predicted that this collector can be used in flotation to remove silica-containing chalcopyrite gangue minerals such as hornblende in magnesite. The first-principle study of minerals can reveal the surface properties of minerals and the adsorption mechanism of minerals and chemicals, and the research content is of guiding significance.
- 1
Study on the damage characteristics of loess-slag-based cemented filling materials under different water-cement ratiosAbstract:
In order to investigate the damage characteristics of loess-slag-based cemented filling materials under different water-cement ratios, scanning electron microscope tests, acoustic emission tests, and PFC2D numerical simulation tests were carried out on the loess-slag-based cemented filling materials. The results show that: when the water-cement ratio is small, the internal hydration reaction of cemented filling materials is more adequate, more hydration products are generated, and the structure of the specimen is dense; The acoustic emission ringing count curves of the cemented filling materials can be divided into five phases: compression-density phase, linear-elastic deformation phase, crack constant-velocity expansion phase, crack surge phase, and after-peak phase; the ringing count characteristics are correlated with the strength characteristics; With the increase of the water-cement ratio, the crack initiation stress and damage stress of the specimen in the process of compression gradually become smaller, and the ratio of the initiation stress, damage stress and peak stress of the cemented filling material is not affected by the size of the water-cement ratio. Shear cracks dominate the damage of cemented filling materials, and with the decrease of the water-cement ratio, the number of cracks increases. The value of the maximum force chain becomes larger, and the change in the water-cement ratio has less influence on the spatial distribution of cracks and force chains inside the specimen.
- 1
Study on the location extraction of concentrate zone separation point in concentrator shaking table based on lightweight fusion networkAbstract:
The key to achieving the intelligence of shaking tables is the target visual detection of mineral zones. However, the current target detection algorithms for mineral zones in shaking tables have issues like slow inference speed, high computational cost, difficulty compressing the model size, and inability to account for model accuracy and detection speed. YC-Lightweight Net, a lightweight fusion network-based detection technique, is suggested in this context. The YC-Lightweight net model RepVit network is used to extract features from shaker mineral sub-band images. The Zoom Cat and Concat modules" feature fusion mechanism, multi-scale feature fusion, lightweight convolution operation, and feature reuse of the VOVGSCSP module are combined to create an effective and lightweight Slim-Neck network. Jump connections are used in the Slim-Neck network to enable the network to process feature information in parallel to improve the inference speed and stability of model training. In order to further compress the size of the YC-Lightweight Net model and reduce its computational complexity, the lamp algorithm is used to adaptively prune it to ensure the feasibility of the model in the deployment of shaking table concentrator industrial equipment. The experimental results show that the YC-Lightweight Net model"s precision P, recall R, mean average precision mAP50, and FPS are 0.984, 0.979, 0.988, and 333, respectively, and the detection precision and detection speed are significantly better than the rest of the model. After pruning, the number of parameters, FLOPs, and model size are 13.9%, 15.4%, and 17.5% of the original model, which greatly reduces the computational complexity of the model and the model size, meets the requirements of the industrial equipment of the shaking table beneficiation plant for the model lightweight, and ensures the stability of the model detection speed and precision.
- 1
Research on Statistical Analysis and Safety Management Countermeasures for Hazards in Non-coal Underground Mines in Sichuan ProvinceAbstract:
In order to strengthen the safety management of non-coal underground mines, clarify the characteristics of safety hazards in non-coal underground mines, and statistically analyze the total number of safety hazards, types of safety hazards, and characteristics of major safety hazards in 52 non-coal underground mines, the following conclusions were drawn: the number of general safety hazards is about 11.5 times that of major safety hazards; the number of safety hazards related to on-site management is about 1.1 times that of safety hazards related to basic management; the number of major safety hazards related to on-site management is about 1.3 times that of major safety hazards related to basic management; the major safety hazards are mainly concentrated on Articles 23, 20, 4, and 31, with 28, 21, 19, and 13 items respectively. Based on the characteristics of major safety hazards, the paper suggests that mining enterprises should strengthen the construction of organizational structures, fully allocate safety funds, and improve and perfect safety facilities, as well as that safety management departments should extend the reach of supervision, innovate supervision models, and enhance the compatibility of supervision. The research findings will provide scientific reference for the safety management work of non-coal underground mines.
- 1
Research on safe thickness of goaf roof based on cusp mutation theoryAbstract:
Traditional theoretical methods mostly use semi-quantitative analysis to analyze the problem of safe thickness of goaf roof, but the destruction of goaf roof is sudden. On this basis, this paper introduces the cusp mutation theory into the study of goaf roof safe thickness, establishes a research model for roof safe thickness, derives the formula for minimum safe thickness of roof, and calculates the theoretical value of goaf roof safe thickness under different lithology conditions and different span conditions based on the current status of goaf in Dabaoshan Mine. Finally, the formula was verified by traditional theory and finite element numerical simulation. The research results show that it is feasible to introduce the cusp mutation theory into the study of goaf roof safe thickness, and the derived formula for minimum safe thickness of goaf roof is reasonable and reliable. The safe thickness of the roof calculated based on the theory of cusp mutation in 12-618, 72-619, 35-584, and 6-618 goaf is 7.3 m, 12.5 m, 9.5 m, and 22.1 m, respectively, which can be used as a basis for on-site goaf disposal.
- 1
The influence effect and parameter optimization of fiber blending process on coarse aggregate filled slurryAbstract:
The rigidity and toughness of coarse aggregate filling backfill are high, and the local energy storage accumulation is easy to cause safety problems. The addition of fiber can improve the toughness and ductility of the backfill and enhance its mechanical properties. Using coarse aggregate, waste rock, rod sand and river sand from Longshou Mine of Jinchuan as raw materials, the effect of fiber blending technology on uniaxial compressive strength of backfill was studied. Design-Expert software was used to analyze the influence of various factors (slurry concentration, fiber volume-rate, cement content) on the early mechanical strength of backfill and optimize the parameters, establish a nonlinear regression model between the value of early uniaxial compressive strength and various factors, reveal the interaction effect between different factors, and calculate the cost of the filling slurry after adding fiber. The results show that the fiber mixing process can significantly improve the compressive strength of the filling body. Compared with the blank group without fiber (3.03 MPa), the strength of the scheme II is increased by 1.32 MPa, which is increased by 43.56 %. In scheme III, the fiber was pre-dispersed, and the strength of the filling material was increased by 0.24 MPa, which was 7.92 %. The significant influencing factors of early mechanical properties of fiber reinforced backfill are as follows: slurry concentration > cement content > fiber volume ratio; the interaction effect between slurry concentration and cement content is significant, which verifies the reliability of the regression model. The cost of the comprehensive material of the filling slurry after mixing the fiber does not change much, which helps to promote the safety and sustainable development of mining.
- 1
Study on the Ultrasonic-reinforced Mechanical and Rheological Properties of Cement-based Filling MaterialsAbstract:
Aiming at the technical bottleneck of low compressive strength, high filling cost and poor filling effect of cement-based filling composite materials, ultrasonic technology was used to improve the performance of cement-based composite filling materials. Through the orthogonal test of three factors and four levels, the effects of ultrasonic power, ultrasonic time and stirring time on the rheological properties and mechanical properties of cement-based filling slurry were investigated, and the strengthening mechanism of ultrasonic action was further discussed. The results show that the compressive strength of the filling body at 3 d, 7 d, 14 d and 28 d increases first and then decreases with the increase of ultrasonic power, ultrasonic time and stirring time. When the ultrasonic power, ultrasonic time and stirring time are 70 W, 4 min and 4 min, respectively, the compressive strength of the filling body reaches the optimal value. This is because the ultrasonic action promotes the dispersion of cement particles and tailings particles in the liquid phase, improves the uniformity of the slurry, increases the activation site on the surface of the cement particles, and promotes the cement hydration process. However, too high ultrasonic power and too long ultrasonic time lead to the reunion of the flocculation structure of cement particles, which inhibits the diffusion of water molecules and the compactness of the slurry structure. The yield stress and plastic viscosity of filling slurry were negatively correlated with ultrasonic power and ultrasonic time, and decreased first and then increased with the extension of stirring time. The appropriate stirring time is beneficial to the dispersion of the slurry and weakens the friction and shear between the particles, while the long stirring time can promote the hydration reaction of the cement, increase the viscosity of the slurry and the amount of hydration products.
- 1
Study on screening, optimization and leaching effect of anorthite leaching bacteriaAbstract:
The use of microbial pretreatment to promote the leaching of calcium and magnesium in anorthite is crucial to strengthen the CO2 sequestration process of mineral carbonation reaction. Compared with traditional acid-base and salt leaching, it has the advantages of low energy consumption, low pollution and broad development prospects. A strain with good adaptability to anorthite was screened from the soil and identified as Phyllobacterium myrsinacearum. The optimum growth conditions of the strain in Czapek"s medium and the optimum leaching conditions of anorthite were explored. The optimum growth conditions of the strain were as follows : pH=6, liquid volume 80 mL, inoculation amount 7%, the optimum carbon source was glucose (20 g/L), and the optimum nitrogen source was NaNO3 (1 g/L). The optimum leaching conditions are as follows: pH=6, inoculation amount 3%, slurry concentration 20 g/L, liquid volume 100 mL. Under these conditions, the leaching rate of calcium can reach 50.38%, and the leaching rate of magnesium can reach 39.91%. The bacteria promoted the dissolution of anorthite through proton exchange and complexation, and accelerated the leaching of calcium and magnesium ions. This discovery improves the utilization rate of mineral resources such as anorthite and provides a new strain for efficient leaching of silicate minerals.
- 1
Prediction of Blast Vibrations in Mines Based on I-GWO-BP Neural NetworkAbstract:
The existing blasting vibration velocity prediction formulas do not have high prediction accuracy when facing the complex ground environment. A BP neural network model optimised based on the Improved Grey Wolf Algorithm (I-GWO) is proposed. The grey wolf algorithm is improved by changing the convergence factor function of the neural network, mapping the Logistic Chaos Algorithm to initialize the position of the wolves, and dynamically adjusting the weights based on the proportional weights of the Euclidean distances of the step lengths, and the I-GWO-BP model is established by combining the blast monitoring data of the Lilou-Wuji iron ore mine, and selecting the core distance of the blast, the maximum loading of a single section, and the total loading of the blast as the input parameters. The results show that the convergence speed and convergence accuracy of the I-GWO-BP model are better than that of the GWO-BP model and the BP model, and the optimization effect is obvious, and the fit between the predicted value and the measured value of the I-GWO-BP model reaches 0.92, and the average percentage of error is 13.84%, which is significantly better than that of the Sardowski equation, and it has a higher prediction accuracy, and provides a certain reference to the control of the blast vibration of the mine. It has a high prediction accuracy and provides a certain reference for the blasting vibration control of mines.
- 1
Testing the Compressive Strength of Soft Powdery Rock in Underground Roadway Using Schmidt HammerAbstract:
Aiming at the characteristics of Jinshandian Mine deep mining underground roadway soft powder ore rock can not be taken out on site complete specimen, to explore the use of Schmidt hammer on the compressive strength of its direct test method.The rebound value was tested by Schmidt hammer in the broken zone of powder ore and skarn in the east-west mining area of Jinshandian Mine at the -425m and -455m levels of the excavated roadway.Based on the national standard and the industry standard of concrete compressive strength measurement formula using Schmidt hammer, according to the Jinshandian Mine rock engineering geological characteristics, the domestic and foreign scholars using Schmidt hammer for rock testing summarized empirical formulas for the preference of the measured rebound value into the above strength measurement formula and empirical formulas, respectively, to build rebound value and compressive strength correlation samples.Mathematical and statistical methods were used to regress the empirical formulas for the two modified strength measurements of the soft powder ore rock of Jinshandian Mine. The empirical formulas were used to value the compressive strength of the soft powder ore rock of Jinshandian Mine, and the conclusions were basically consistent with the results of the Inversion method of the soft powder ore rock roadway of Jinshandian Mine based on the convergence value of the roadway.The research results have explored a feasible solution for the situation that the compressive strength of rocks cannot be directly tested under adverse engineering geological conditions in underground engineering.
- 1
Influence of blasting vibration on stability of first-step stoping backfill under different stoping sequenceAbstract:
In the second step mining of open stoping with subsequent filling method, the blasting vibration has a significant influence on the stability of the artificial pillar formed after the cement filling in the one-step goaf. Based on the background of mining in the transition from open-pit to underground in Sijiying Iron Mine, the 3D geological and numerical calculation model of stope under blasting load are established by using the FLAC numerical simulation method, and three mining sequences of stope in the mining panel are studied, they are "one side to the other side", "central to both sides" and "two sides to the center". When the distance between the blasting hole and the backfill body is 1.0m and 1.5m respectively, the characteristics of the effect of blasting on the stability of the artificial pillar are obtained, and the strength demand of the backfill body is inverted. The results show that: (1) when the peak pressure of the blasting load is 15 MP, with the increase in the distance from the hole to the backfill body, the maximum principal stress in the artificial pillar decreases, and the concentrated stress and plastic failure range in the backfill body under the "side-to-center" mining mode are the least, which is the most favorable to the stability of the backfill body; (2) when the mining of the second step stope is "pushed from both sides to the center", the longer the distance between the blasting hole and the backfill body, the smaller the plastic zone in the backfill body, which is more favorable to the stability of the backfill body. Meanwhile, the larger the distribution range of the shear plastic zone formed in the two-step mining ore body, which is conducive to the mining of the two-step stope; (3) the strength of cemented backfill prepared by cementing powder and total tailings with a ratio of 1:6 can meet the stability requirements of artificial pillars.
- 1
The study on the influence of groundwater erosion on the mechanical properties of polypropylene fiber-reinforced backfillAbstract:
As mining operations progress and the depth of mining increases, backfill bodies are subjected to the effects of high ground stress, mining disturbances, and erosion by groundwater, among other harsh underground environments. To investigate the impact of groundwater erosion on the mechanical properties of tailings cemented backfill with polypropylene fiber, first, uniaxial compression and Brazilian splitting tests were conducted on specimens with different fiber contents to select the specimens with superior mechanical properties. Subsequently, based on the groundwater erosion environment, uniaxial compression and acoustic emission monitoring tests were carried out to study the evolution characteristics of damage and failure. The results show that with the increase of polypropylene fiber content, the compressive strength of the backfill body first increases and then decreases, with the best performance at a dosage of 0.3%. After groundwater erosion, the acoustic emission cumulative ring count characteristics can be divided into three stages: initial activity, steady growth, and rapid growth, with a more significant sudden destruction precursor occurring during the steady growth stage. Durability is shown as pH = 9 > pH = 7 > pH = 5 > non-eroded. As the pH value of groundwater increases, the RA-AF shear crack signal continues to decrease, and the damage and failure of the backfill body shift from shear failure to tensile failure. This indicates that alkaline groundwater has an enhancing effect on the durability of backfill bodies with polypropylene fibers.
- 1
A Study on the Prediction of Compressive Strength in Gold Tailings Concrete Using an Improved CNN-GRU ModelAbstract:
Gold tailings-based concrete has a wide application potential as an environmentally friendly material. However, due to the complexity of its material composition, there are limitations in the traditional methods for predicting its compressive strength. To this end, this paper proposes an improved deep learning based binary fusion model-fusing convolutional neural network (CNN) and gated recurrent network (GRU) for accurately predicting the compressive strength of gold tailings-based concrete. Moreover, a new hybrid optimization algorithm based on adaptive particle swarm optimization (PSO) combined with differential evolutionary algorithm (DE) is used to further optimize the model performance. In this study, the mineral and chemical composition and particle size distribution of gold tailings were firstly analyzed, and their leaching toxicity was detected according to the relevant standards, which ensured the safety as concrete materials. Subsequently, the gold tailings concrete dataset was constructed through experiments and applied to the training and validation of the model. In order to further verify the predictive ability of the model in real engineering, it was applied to real engineering cases to verify its performance. The results show that the proposed model exhibits high accuracy and low error in both the training and testing phases, and is able to effectively predict the compressive strength of gold-tailings-infused concrete. The application of real engineering cases further proves the application potential of the model in engineering practice, and provides new perspectives and methods for the resource utilization of gold tailings and the prediction of compressive strength of high-performance concrete.
- 1
Research progress on the recovery of valuable elements in waste lithium iron phosphate batteriesAbstract:
With the deepening of environmental protection concepts and the advancement of battery technology, the development of new energy vehicles has entered an explosive growth period, and at the same time, a wave of retired batteries has been stirred up. In response to the challenge of efficient and green recycling of waste lithium iron phosphate batteries, comprehensively reviews the main literature on the recycling of lithium iron phosphate batteries at home and abroad in recent years, and introduces the latest technological progress in pretreatment, regeneration and repair, as well as pyrometallurgical and hydrometallurgical recycling. By analyzing and comparing the main characteristics and defects of various recycling technologies, the advantages of wet selective leaching were pointed out, and the importance of comprehensive recovery of all components and the necessity of multi process collaboration in future recycling processes were emphasized.
- 1
Research on Intelligent Identification of Rock Thin Section Minerals Based on Deep LearningAbstract:
With the continuous advancement of mineral resource exploration technologies, the intelligent identification of rock minerals has become increasingly vital in the domain of mineral composition analysis. In response to the substantial challenges posed by the intricate texture structures and diverse mineral morphologies in rock thin section images, a Mineral YOLO model based on an improved YOLOv8 algorithm is proposed, specifically designed for rock thin section mineral recognition tasks under polarized light microscopy. This model incorporates the LSK module to improve the discrimination between target and background information, integrates ODConv technology to reduce background interference and enhance convolutional network performance, and refines the loss function to increase bounding box localization precision. During model training, a composite augmentation technique is applied to enrich the self-constructed dataset, thereby expanding sample diversity to facilitate better generalization. Validation on a dedicated dataset demonstrates that the model attains an average accuracy of 83.3% and an F1 score of 78% across six mineral types. Compared with the benchmark algorithm, the model achieves gains of 3.0% in accuracy and 1% in F1 score, substantiating its efficacy and accuracy in rock mineral identification and enabling precise recognition of mineral compositions in rock thin sections.
- 1
Study on improving quality and reducing consumption ofcomplex and high resistance ventilation system in ultra-deep well miningAbstract:
Some metal mines in China are gradually turning to deep or ultra-deep Wells. In order to solve the ventilation difficulties, the continuous deterioration of underground working environment and the continuous improvement of ventilation energy consumption faced by ultra-deep Well mining. Taking Hongtongshan Copper and Zinc Mine as the research object, the study on improving the quality and reducing the consumption of ventilation system was carried out. Through investigation and measurement, simulation, theoretical research, calculation and analysis, practice test research methods, the research and application work such as the construction of complex low-trend ventilation network in ultra-deep well long strike mine, the optimization of main fan setting, the addition of non-damper high air pressure injection auxiliary fan, and the remote intelligent frequency conversion control of main fan are carried out. The ventilation resistance of the whole mine was reduced by 56.39%, the identification indicators of 7 ventilation systems were significantly increased, with an average increase of 20.43%, the ventilation energy consumption cost was saved by 3.023 million yuan /a, and the ventilation system had a significant effect of improving quality and reducing consumption, providing a safety guarantee for ultra-deep mining mines. The research results can provide reference for similar mine ventilation systems to improve quality and reduce consumption.
- 1
Investigation and slope stability analysis of slopes with old landslide in an open pit mineAbstract:
In order to analyze and study the stability of the existing landslide in an open-pit mine, to ensure its safe production and to prevent the occurrence of geological disasters, the seismic mapping method is used, in order to obtain the position of the existing slip surface, the transient electromagnetic method and other geophysical prospecting methods are used to investigate the slip surface of the existing landslide, and then the stability of the existing slip surface is calculated and analyzed by Bishop Slice method, then the most dangerous slip surface of the whole slope was searched and analyzed by the mode search method combined with the Bishop Factor of safety method, and the corresponding Factor of safety of the most dangerous slip surface was obtained and its stability was analyzed. The results show that the corresponding Factor of safety calculated for the existing slip surface is higher, which indicates that the slope body with the existing slip surface is more stable as a whole. The most dangerous slip surface with smaller Factor of safety can be found in parts of the existing landslide body and in other parts of the landslide body by mode search method. The above analysis shows that it is more efficient to use geophysical prospecting method to survey the existing slide surface. Bishop Slice method is used to calculate the stability of the existing slide surface, and the whole stability of the existing landslide can be analyzed. The whole slope can be analyzed by the combination of the mode search method and the Bishop slice method, and the part on the existing landslide can be searched out, these results can be used for better monitoring and measurement of the slope, as well as for timely and comprehensive treatment of the Factor of safety.
- 1
AI Early Warning Management System Module Algorithm and Multi-Scenario Applications for Underground Coal MiningAbstract:
The implementation and application of AI management system module algorithms in coal mines are pain points and difficulties in the field. Promoting integrated mine management can help promote the development of mines and effectively improve their intelligent monitoring capabilities. Based on mine intelligent identification technology, the architecture of three-level and five-layer mine AI intelligent identification system is constructed. The algorithm of the mining AI management system is concentrated in the comprehensive mining module, excavation module, transportation module, and general module. Formed the software + server intelligent vision application model. The comprehensive mining module adopts CNN, Yolo-FastestV2 and YOLOv3 models to achieve recognition of coal mining equipment and regional target detection and support attitude detection; the tunneling module uses YOLO model to identify the foreboding beams and human body targets; the transport module proposes a YOLACT algorithm recognition model to identify the belts, foreign objects and large lumps of coal; and the general-purpose module implements helmet, personnel behavior, and environment detection through OpenCV, YOLO, and YOLOv4 models. The mean average accuracy of the YOLACT model training results box is 86.79%, and the mean average accuracy of mask is 83.58%. Synthesis mining face real-time display of equipment, personnel, environment and other state results; digging face enables the identification and alarm of personnel intrusion into hazardous areas and abnormal operating processes; transport face detection belt coal volume, large pieces, foreign objects, etc.; AI intelligent transportation tracks and monitors targets in real time and warns of abnormal behavior; three violations management monitoring area inspectors, unsafe behavior alarms, underground key area alarm voice reminders; intelligent mine to achieve comprehensive supervision of the entire mine. The research promotes the deep integration of AI intelligent technology and coal mine safety production, realizing intelligent application scenarios that reduce manpower and improve efficiency, which is of great significance to the intelligent mining of coal mines in China.
- 1
Experimental Study of Copper-lead-zinc Re-separation of One Iron Tailings in PeruAbstract:
In this study, the copper-lead-zinc re-separation experimental study was carried out on an iron tailings in Peru. Assays returned 0.38% copper, 0.79% lead, 2.68% zinc and 8.45% sulfur. The ore structure was more complex, and the sulfide types were more complex. Besides chalcopyrite, pyrrhotite, sphalerite, galena, marcasite were seen, and the ore’s overall oxidation degree was weak. Based on the research results of ore process mineralogy, the process flow of "copper lead zinc partial floating-copper and lead zinc separation-lead and zinc floatable re-separation" was utilized on the experimental research of the optimization and improvement on flotation reagents. The results showed that the existing flotation reagent in the concentrator had strong adaptability to the ore, and the foam enrichment ratio of the roughing operation could be improved by adding the regulator CL mixture in the roughing operation. Butyl xanthate + ester-112 had strong adaptability in the mixing rough separation operation, and its ability to capture and selective fine-grained copper, lead and zinc was strong. The sodium sulfide + sodium metabisulfite inhibitor system of copper-zinc separation flotation had strong adaptability to the raw ore, and its technical indicators of copper-lead-zinc separation surpassed the other inhibitors. In the floatation process of lead and zinc, 25# black powder had a strong selectiveness and attainment of lead minerals after the separation of copper and lead zinc, and its technical indicators to floatable re-separation of lead and zinc outnumbered butyl xanthate + ester-112. After optimization, the final copper concentrate rate from the iron taillings was 22.03% copper and the copper recovery rate was 64.93%; The zinc concentrate grade was 47.12%, and the zinc recovery rate was 72.00%; The lead-zinc concentrate grade was 21.65% lead, 25.13% zinc, 58.84% lead recovery and 19.95% zinc recovery.
- 1
Study on the Spatio-temporal Evolution Characteristics of Crack Propagation and Early Warning in Rock FractureAbstract:
Dynamic hazards such as rock bursts, triggered by mining disturbances, severely limit the exploitation of deep mineral resources. Investigating the expansion and evolution of internal cracks in rocks is crucial for understanding rock failure mechanisms and for early warning of such disasters. Based on this, the spatio-temporal response characteristics of acoustic emissions (AE) under uniaxial load on granite were measured. The single-link cluster (SLC) method was employed to construct the SLC structure of AE events, and a spatial correlation length metric associated with these events was built. The three-dimensional positioning and energy attributes of AE events depict the initiation, propagation, and evolution of microcracks in granite samples. As stress increases, the link lengths within the SLC structure decrease, enhancing the internal correlations among AE event clusters and reducing the spatial correlation length of localized areas. Near the point of granite fracture, a sudden increase in spatial correlation length due to stress redistribution and transfer within the sample can serve as an early warning indicator of granite instability. SLC is an effective method for studying the evolution of rock fracture expansion and will provide significant insights for the early warning and prevention of dynamic disasters such as rockbursts.
- 1
Experimental study on characterizing grouting filling effect based on polarizability parametersAbstract:
In order to better monitor and detect the filling form and effect of goaf, a study on the characterization of grouting filling form and effect with polarization rate as the target was carried out through indoor testing analysis and experiments based on resistivity parameters. Seven different kinds of cement were selected and equipped with five different kinds of graphite powder blending, and a total of 140 specimens were poured to analyze the influence of resistivity and polarizability parameters of cement-based grouting filling materials, and the electrical characteristics and compressive strength relationship of different cement types and ratios were studied, and tested. The indoor test results indicate that the compressive strength decreases with the increase of graphite powder content; the polarizer increases with the increase of graphite powder content, and increases rapidly after more than 10%, and after more than 20%; Besides the sulfur aluminate cement, the amount of graphite powder has little influence on the resistivity of cement-based grouting filling material. In the case of no obvious difference in the resistivity before and after grouting in the goaf, the filling form effect can be visually characterized by polarizability (the polarizability value of filling material is more than 3 times greater than that of surrounding rock), which is of great significance for broadening the field of grouting exploration and effect.
- 1
SBAS-InSAR technology integrates SOA-BP model for large-scale subsidence monitoring and prediction in mining areasAbstract:
Ground subsidence refers to a geological phenomenon in which the surface soil of the earth"s crust is compressed under natural and human factors, resulting in a regional decrease in ground elevation. To prevent this progressive and gradual geological hazard, efficient large-scale prediction of ground subsidence is particularly important. In response to the problems of insufficient monitoring points in existing prediction models and the tendency of BP neural networks to fall into local optima, this paper proposes a SOA-BP prediction model by optimizing the weights and thresholds of BP neural networks based on the SOA algorithm. Compared with traditional single point prediction, this model utilizes the temporal settlement values of multiple highly correlated points to achieve large-scale and accurate prediction of mining areas. Using SBAS InSAR technology to process 59 Sentinel-1A ascending orbit SAR images covering the Xieqiao mining area, and extracting temporal subsidence values of 6997 high coherence points in the area. Using the SOA algorithm to optimize the BP neural network model, the settlement time series prediction of the settlement area was carried out, and the prediction accuracy was calculated. Research has shown that the optimized SOA-BP model reduces root mean square error by 81.13% and average absolute error by 82.77% compared to the unoptimized BP model. The predicted root mean square error does not exceed 4.0384mm, and the predicted average absolute error does not exceed 4.4665mm. The proposed method provides technical support for ensuring safe production in mining areas and achieving scientific disaster prevention and reduction.
- 1
Study on Subsidence Law of Surface Road Engineering under the Condition of Overlapping Occurrence of Quicksand Layer and Goaf(1. School of Safety Science and Emergency Management, Wuhan University of Technology, Wuhan, Hubei 430070;Abstract:
In order to study the subsidence law of surface road engineering under the condition of overlapping occurrence of quicksand layer and goaf, taking the goaf of Dangyang gypsum mine as the engineering background, the finite element difference software FLAC3D was used to numerically simulate the distribution law of surface displacement under the condition of overlapping occurrence of quicksand layer, goaf and quicksand layer and goaf, analyze the variation law of surface subsidence, evaluate the influence of cavity of quicksand layer on the stability of stope and surface road section, and put forward the control scheme of goaf. The results show that, under the action of goaf and goaf in quicksand layer, the surface subsidence curve is inverted V-shaped, the settlement displacement value gradually decreases from the center to the periphery, and the settlement peak value is concentrated in the range of K5+617-K5+717. The surface subsidence values of the same monitoring line (road center line) from west to east are 12 mm, 167 mm and 16 mm respectively. The surface subsidence values of different monitoring lines (south line, middle line and north line) are 22 mm, 167 mm and 69 mm respectively. The displacement and settlement in the central area of the road centerline is large, showing the law that the displacement and settlement first increase and then decrease from west to east, and the settlement on the north and south sides is small; The overlying strata at different depths above the quicksand layer all move from west to east with the increase of the distance from the working face, and the deformation first increases and then decreases. In addition, with the increase of the distance from the surface, the settlement of overlying strata above the quicksand layer shows a decreasing trend in the central area (R<100 m) and an increasing trend in other areas (R>100 m), so the surface rock movement range is delineated as 100 m under the action of the quicksand layer goaf. The research results can provide theoretical basis for safe mining of gypsum mine and route planning of road expansion project under quicksand layer.
- 1
Collaborative Optimization Control Method for Vehicle Traffic at Mine Unsignalized IntersectionAbstract:
In the development of intelligent mine unmanned transportation system, unsignalized intersection traffic control is an important link to improve transportation efficiency and ensure transportation safety. Aiming at the limitation of bicycle perception ability and decision-making ability, this paper designs a collaborative optimization control method based on vehicle-road collaborative system. The driving information of all vehicles within the scope of unsignalized intersections is used as the basis for regulation, and three aspects of conflict detection, right-of-way decision-making and driving optimization are carried out in a cycle, and multi-level safety boundary conditions are set. Based on PreScan/Simulink, a joint simulation platform for intersection collaborative control was built to design a validation scenario for open-pit transportation involving multiple conflict situations and verify the control method. The simulation results show that the control system can ensure that multiple vehicles can pass through the unsignalized intersection in a coordinated and orderly manner under the premise of the minimum safety distance, and the overall traffic efficiency of the intersection is high.
- 1
Research progress on collector to remove impurity for magnesite by flotationAbstract:
With the exhaustion of high-grade magnesite resources, it is very important to carry out fine purification of low-grade magnesite through beneficiation. Flotation is the most effective method for magnesite beneficiation, and the collector is the core flotation reagent that determines the flotation effect. Although scholars have done a lot of research on the flotation of magnesite in recent years, there is no systematic summary of the research progress in collectors. Based on this, the research status of collectors in flotation impurity removal of magnesite at home and abroad is introduced, and the research progress of the mechanism of collectors and magnesite and its gangue minerals is analyzed from the macro perspective of conventional characterization test technology and micro perspective of molecular simulation technology. Comprehensive analysis shows that it is necessary to strengthen the research on new collectors for synergistic impurity removal; it is predicted that the combination of experiment and molecular simulation technology to verify the flotation performance and mechanism of collectors will be the focus of future research. The development of new collectors needs to have high selectivity and recovery ability, at the same time, respond to the national “double-carbon” strategy, and be green, environmentally friendly, and pollution-free. The research results can provide a theoretical basis and support for the sustainable development of magnesite resources and the development of flotation reagents.
- 1
Research on mechanical properties of high-sulfur tailings cemented backfill excited by industrial magnesium slagAbstract:
In this study, high-sulfur tailings and Gobi aggregate were used as mixed filling material to explore the influence of industrial magnesium slag excitation on the mechanical properties of high-sulfur tailings cemented backfill. The effects of different magnesium slag dosages on the compressive strength, stress-strain curve characteristics and damage mode of the filling were analyzed. NaOH was used as the alkaline excitant to further investigate the mechanical properties of the filling through orthogonal experiments. The experimental results showed that the appropriate amount of magnesium slag helped to increase the aggregate proportion of high-sulfur tailings sand and promoted the development of early strength. The compressive strength of the cemented backfill with NaOH excitant was increased up to 4.54 MPa. Extreme analysis of variance (ANOVA) showed that magnesium slag doping and tailing bone ratio had a more significant influence on the strength, in which magnesium slag doping (10%) had an important role in the early strength of 7d, and the tailing ratio (1:1) was important in the long-term strength of 28d. This study provides a theoretical basis for the resource utilization of high sulfur tailings and magnesium slag and provides a new idea for the optimization of mine filling materials.
- 1
Study on the Mechanical Properties and Engineering Applications of Fiber-Reinforced Wet-Sprayed ConcreteAbstract:
Traditional wet-mix shotcrete, as a brittle material, exhibits significant deficiencies in deformation and crack resistance. Fiber-reinforced concrete, with its superior performance in both aspects, has become a focal point of research. To evaluate the support performance of fiber-reinforced wet shotcrete, a series of tests were conducted, including uniaxial compressive tests, notched beam flexural toughness tests, and disk flexural tests. The experimental results indicate that, although the addition of fibers slightly reduces the compressive strength of wet shotcrete, the incorporation of steel fibers significantly enhances both flexural strength and energy absorption capacity. Notably, at a fiber dosage of 40 kg/m3, the flexural strength increased by approximately 1.8 times, and the energy absorption capacity exceeded that of plain concrete by more than 15 times. When the dosage of 4D steel fibers reached 35 kg/m3, the post-peak flexural strength increased by about 2 times. Industrial trials demonstrated that the compressive strength of steel fiber-reinforced wet shotcrete can reach 25 MPa, with a sprayed layer thickness maintained between 100 and 150 mm, minimal rebound, and notable support effectiveness.
- 1
Evaluation and Prediction of the Stability of the Peripheral Rock in the Deep and Fragile roadway of Jinchuan No.2 Mining AreaAbstract:
For the stability of the three middle sections of the Jinchuan II mining area, the maximum principal stress, roadway convergence rate, rock body integrity (Kv), rock quality (RQD), and support effectiveness were selected as evaluation indexes. Utilizing the combined empowerment-boundary cloud modeling algorithm, the stability of the roadways in the deep parts of the three middle sections during the coordinated mining period was comprehensively evaluated and predicted, then compared with on-site working conditions. The results indicate that the stability grades of the roadways in the 1018 m, 934 m, and 814 m subsections across different mining phases primarily fall within grades II to III, although variations exist in the stability of the main roadways in each middle section. Currently, the stability of the roadway in the 1018 m section is superior to that in the 934 m and 814 m sections, with the western and eastern areas of the 1018 m section exhibiting better stability than the central area. Conversely, the
- 1
Risk Analysis of Water Conduction in Poor Disturbance Sealing Bore-holes in Underground MiningAbstract:
A gold deposit in Shandong Province occurs below the sea level as a whole, and the surface seawater always threatens the safety of mine production. When the poorly sealed boreholes are connected to the seawater to form a water channel with strong concealment, it poses a water hazard threat to roadway excavation and working face mining. In this paper, COMSOL Multiphysics simulation software is used to simulate the working face with poor sealing boreholes. The results show that the stress redistribution of rock strata occurs after mining, and the water conductivity of poor sealing boreholes is greatly affected by mining, and the risk of water inrush is far more than that of well-sealed boreholes. When the separation phenomenon occurs between the filling medium and the hole wall in the poorly sealed borehole, the greater the separation distance, the greater the risk. The model of poorly sealed boreholes shows that under different water pressures, the effect of poorly sealed boreholes is quite different. The grea
- 1
Research Status of Glycine Green Leaching ProcessAbstract:
The glycine leaching system represents a novel green hydrometallurgical leaching process. This article delves into the limitations of current hydrometallurgical technologies in terms of environmental friendliness. It further examines the unique physicochemical properties of glycine and its distinct advantages in the hydrometallurgical industry. The study suggests that the glycine green hydrometallurgical leaching process has the potential to expand existing hydrometallurgical technologies, particularly in the field of rare and precious metals, offering a viable alternative to traditional cyanide gold extraction techniques. The article reviews the developmental history of the glycine hydrometallurgical leaching process and outlines the current research status and commercial trends of this technology in processing various types of mineral resources. It systematically summarizes the main challenges currently faced by the glycine green hydrometallurgical leaching process and outlines future development trends and prospects from the perspectives of the process"s applicable fields, leaching efficiency for different target metals, universality of secondary resources, and the mechanism of action of the glycine synergistic leaching system.
- 1
Study on the influence mechanism of different magnetization methods on reverse flotation of hematiteAbstract:
To investigate the effect of magnetization treatment on the reverse flotation behavior of hematite in the dodecylamine cassava starch system, water, starch, dodecylamine, and slurry were magnetized separately. The mechanism of magnetization treatment in hematite reverse flotation was analyzed by detecting the changes in drug adsorption, contact angle, and zeta potential under different magnetization methods. The results showed that under optimal conditions, magnetized water, magnetized starch, and magnetized slurry could increase the flotation recovery rate of hematite by 4.16, 2.78, and 3.84 percentage points, respectively. Magnetized water, magnetized starch, and magnetized slurry can increase the starch adsorption capacity on the surface of hematite particles and reduce the contact angle of the solution on their surface, while magnetized dodecylamine has the opposite effect; Magnetized water and starch respectively shift the zeta potential of hematite particles positively, while magnetized dodecylamine shifts the zeta potential of hematite particles negatively. Magnetized water and magnetized starch promote the adsorption of starch on the surface of hematite, magnetized dodecylamine inhibits the adsorption of starch on the surface of hematite, and magnetized slurry promotes the hydrolysis of hematite surface, allowing more starch to be adsorbed on the surface of hematite particles.
- 1
Research Progress and Development Direction of Wolframite Flotation ReagentsAbstract:
With the continuous exploitation of wolframite resources, the raw ore gradually becoming lean and refined. It is difficult to improve the beneficiation index by conventional gravity concentration. Flotation has become an effective means to improve the recovery efficiency of fine wolframite. In recent years, flotation technology has mainly focused on the development of flotation reagents. Taking the development of wolframite flotation reagents as the starting point, the development of collectors, activators and inhibitors in wolframite flotation is introduced. The assembly methods, advantages and disadvantages and indexes of reagents are described in detail. The flotation process mechanism of flotation reagents and the mechanism of solid-reagent surface action are analyzed. This paper provides a reference for improving the flotation index of wolframite, the application of flotation reagents and the development of new reagents.
- 1
Research and prediction of ore fluidity in a chute based on slump testAbstract:
In order to improve the accuracy of the prediction of ore fluidity in the ore storage section based on numerical simulation and laboratory similarity test, the parameters of the parallel bonding model obtained based on slump and expansion test were introduced in the numerical simulation process, and the results obtained by the numerical simulation method were highly consistent with the laboratory similarity test. The results of the study show that the fluidity of the ore shows a significant downward trend in the range of 0% to 9% moisture content. In particular, when the moisture content reaches 7% to 9%, the ore is prone to clogging, so this moisture content range should be avoided in the actual drawing operation. On the contrary, when the moisture content is between 3% and 5%, the fluidity of the ore is the best, and it is recommended that the moisture content of the ore should be controlled within this range in practical engineering. In addition, the results show that when the ore storage height is increased from 20m to 40m, the ore mass flow rate reaches the maximum value when the ore storage height reaches 40m, and when the height continues to increase from 40m to 60m, the ore mass flow rate tends to be stable and decreases slightly.
- 1
Study on optimization of roof bolt support parameters of broken ore bodyAbstract:
Bstract? In order to solve the problems of roof instability and material waste caused by unreasonable values of roof supporting parameters, the optimization research of supporting parameters was carried out based on the North stope of Zhongguan Iron Mine. Firstly, based on the suspension theory and loose ring theory combined with the numerical simulation results when not supported, the thickness of the loose zone was determined by taking the plastic zone as the loose ring, and then the length interval of the bolt was obtained from 2.4 to 4.4m. According to the rock mass quality, the row spacing between the bolts is 0.8m×0.8m and 1.2m×1.2m, the lengths of the bolts are 2.4m and 4.4m, and the anchorage forces are 17.5MPa and 20MPa, respectively. FLAC 3D numerical simulation is used to establish the mining model. The distribution and variation rules of stress, displacement and plastic zone of the roof were compared and analyzed. Finally, based on the simulation results, using the index satisfaction method, the roof settlement, the height of stress release zone, the area of plastic zone and the total length of the bolt were selected to establish the optimization model of bolt parameters considering safety and economic benefits, and the highest comprehensive satisfaction was 0.899. The optimal scheme was determined as 0.8m×0.8m row spacing, 4.4m bolt length and 20MPa anchorage force. The simulation results provide theoretical support for the determination of the bolt parameters of the orebody.
- 1
Spectrum Evaluation on Chlorophyll Content of Astragalus adsurgens Pall. under Inoculation Mycorrhiza and Different Planting Patterns in Opencast Mine DumpAbstract:
In order to rapidly and non-destructively monitor plant chlorophyll content, two different microbial reclamation treatments (inoculation and control) were set up, along with four sowing ratios of leguminous: gramineous plants (1:1, 1:2, 1:3, 2:1) for six herbaceous species (Astragalus adsurgens Pall., Medicago sativa L., Leymus chinensis, Agropyron cristatum L., Elymus sibiricus L., Bromus inermis Leyss.). Chlorophyll content and spectral reflectance of Setaria viridis in experimental plots were measured, and three spectral indicators—original spectral reflectance, inverse-log reflectance, and first-order differential reflectance—were used. BP neural network regression, Support Vector Machine (SVM) regression, and Random Forest (RF) regression modeling methods were applied to establish models based on plant spectral feature curves under different treatments. The results indicated that inoculation treatment increased chlorophyll content, and chlorophyll levels varied under different sowing ratios. Compared with the original spectral reflectance (R), the modeling accuracy using inverse-log reflectance (LR) and first-order differential reflectance (FDR) was improved to varying degrees, with FDR showing the highest modeling accuracy. Under microbial reclamation conditions, the RF regression model exhibited the highest precision. For different sowing ratios, models based on BP neural network regression showed higher accuracy in the leguminous: gramineous ratios of 1:2 and 1:3, while RF regression models demonstrated better precision in the 1:1 and 2:1 ratio.
- 1
Optimization Of Stope Structure Parameters Based On IAHP-TOPSIS Model With Downward Approach Filling MethodAbstract:
In this paper, based on the background of the treatment of empty zone, recovery of hidden resources and mining of middle-depth ore body in the mining process of sharply inclined thin vein group ore body, and based on the concept of synergistic mining, a four-fold mining concept is put forward: the mining method is converted from the air field method to the avalanche falling method, the hidden resources are made to cover the rock layer in middle-depth mining, the empty zone is used as a free blasting space for the cutting chute and the bedding layer, and the shallow holes are applied in synergistic manner with the middle-depth holes. And in this way to empty field method to avalanche method mining design and application. Mining practice shows that: the change in mining method effectively solves the problem of safety hazards in the airspace, hidden resources recovery and safe and efficient mining of the middle and deep ore body, greatly increasing the resource recovery rate, providing great help for mine safety, but also for the same kind of mines to deal with similar problems to provide a reference.
- 1
Response Surface Methodology-Based Study on the Activity of Coal Gasification Slag and Volcanic Ash: Optimization of Composite Excitation DesignAbstract:
Coal gasification slag (CGS) is an industrial solid waste rich in silica-aluminum components with latent volcanic ash potential. However, a significant portion of these components exist in a crystalline state with low volcanic ash reactivity. By enhancing its reactivity, CGS can be effectively utilized in large-scale applications, such as mine filling, thus promoting its resource utilization. This study explores the impact of composite excitation using four different excitants on the volcanic ash activity of CGS, employing the response surface method. The compressive strengths of specimens at various time points were measured to calculate corresponding activity indexes, evaluating the volcanic ash activity. A quadratic polynomial regression model was developed to determine the optimal ratio of the four excitants for enhancing CGS activity through multi-objective optimization. The findings indicate that the regression models exhibit strong fitting capabilities, with correlation coefficients close to 1. Sodium silicate primarily influences the 3-day and 7-day activity indexes, while calcium carbide slag significantly affects the 28-day activity index of CGS during composite excitation. Utilizing the Design-Expert software for multi-objective optimization yielded optimal compound excitation ratios: 0.97% calcium carbide slag, 1.61% desulfurized gypsum, 2.55% sodium sulfate, and 10% sodium silicate. Experimental validation demonstrated that the error between predicted and measured values was below 10%.
- 1
Research on roadway support technology based on the distribution law of plastic zone in deep crushed peripheral rockAbstract:
In order to solve the problem of difficult roadway support in deep crushed surrounding rock, the range of plastic zone is studied. Taking the roadway in the broken section of a mine as the engineering background, the current situation of roadway damage is investigated, and from the physical properties of the roadway surrounding rock itself, the elastic-plastic mechanics model applicable to this type of surrounding rock is established through theoretical analysis, the formula for calculating the radius of the plastic zone of the roadway is deduced, and the influence of cohesion and angle of internal friction on the plastic zone is analyzed in the condition of the coefficient of lateral pressure λ=1. Using Flac3D software, a numerical simulation model was established to verify the reasonableness of the theoretical calculation results. The investigation results show that: the reason for the damage of the roadway under the original support is the poor nature of the surrounding rock and the neglect of the plastic zone range by the support parameters; the numerical simulation shows that: the cohesion and the internal friction angle of the surrounding rock have a significant effect on the range of the plastic zone, and when the cohesion and the angle of the internal friction are large, the range of the plastic zone is small, and the enclosing rock of the roadway tends to be stabilized. Especially, when the internal friction angle is 35° and the cohesion is 3MPa, the change curve of the radius of the plastic zone turns, indicating that this combination of parameters is the key threshold of the bearing capacity of the surrounding rock. According to the theoretical analysis and numerical simulation results, the joint support scheme of “anchor (rod), net, spray + full-section anchor cable + base plate anchor cable” is proposed, and through the on-site displacement monitoring, the top and base plate displacement of 61mm and the displacement of two gangs of 40mm are successfully controlled, which effectively guarantees the stability of the tunnel surrounding rock. The results of the study provide theoretical basis and practical guidance for the tunnel support technology of deep broken surrounding rock.
- 1
Shear strength criterion for progressively weakened non-persistent jointed rock mass under freeze-thaw cyclesAbstract:
The frost heaving cycle damage often leads to geological hazards of jointed rock mass in cold area, and the key factor that determines the stability of jointed rock mass is the shear strength of rock mass. There are some deviations in the generalized criteria for calculating the shear strength of jointed rock in cold regions under the combined effect of freeze-thaw cycles and shear loading. The similar material test method is adopted to carry out freeze-thaw cycle and shear experiment of rock mass. In this case, a new shear strength criterion of non-persistent jointed rock describing the progressive deterioration by freeze-thaw cycles is proposed. Firstly, the weakening law of specimens under the coupling effect of freeze-thaw and shear is derived according to the shear test results of freeze-thaw specimen, which demonstrate that the shear strength of freeze-thaw specimens consists of three parts including weakened and non-weakened rock bridges as well as joint surface. On this basis, the weakening law of rock-bridge is quantitatively represented by the coupled damage model, and the modified Jennings shear strength criterion which considers the coupled effect of freeze-thaw cycle and shear is achieved. Finally, the data analysis shows that it can accurately predict the shear strength of non-persistent jointed rock under the influence of freeze-thaw cycles, the average relative error between the experimental and theoretical results is 2.1%，and the theoretical calculation results by the modified Jennings criterion agree better with the experimental results, which can provide a reliable basis for the study of freeze-thaw rock mass damage and safety protection of jointed rock mass in cold regions.
- 1
Study on the full-time sequential stress evolution law of deep phosphate mine tailings concrete backfill bodyAbstract:
With the gradual increase in the depth of phosphate mining, the strength of the filling body under the filling mining conditions becomes increasingly higher. How to rationally design the strength of the filling body is a problem confronted by most mining areas. To rationally design the strength of the filling body, a method combining on-site measurement in the mining area and numerical simulation was employed to conduct real-time stress monitoring of the cemented filling body in the stope throughout the entire time sequence (filling stage, curing stage, and bearing stage), thereby obtaining the evolution law of the internal stress of the filling body. Numerical modeling and analysis were carried out using the real stratum information of the mining area to analyze the stress evolution law of the filling material from entering the stope to solidification and load-bearing throughout the entire process. By comprehensively comparing and analyzing the data of the numerical simulation and the on-site fiber Bragg grating stress sensor, a contrastive analysis was conducted on the evolution of the mining stress of the filling body throughout the entire time sequence. The on-site measurement results indicate that the filling body is a passive bearing entity. Only after the pillar adjacent to the filling body is mined through blasting does the filling body gradually start to bear the load. The internal stress within the filling body on one side of the pillar after its mining reaches 0.714 MPa. The numerical simulation results show that the internal stress within the filling body on one side of the pillar after its mining reaches 2.0 MPa, and when both sides of the pillar are mined, the internal stress within the filling body reaches 3.0 MPa. The filling body with a 28-day design strength of 3.0 - 4.0 MPa adopted in the mining area can withstand the corresponding disturbance, and the filling body is in a safe state.
- 1
Study on the degradation model of overlying rock strength under different mining heights and the reasonable initial mining heightCHEN Weichong1,HUANG Jingzhu2,XIAO Jian2,WU Rui3Abstract:
To study the degradation law of overburden strength caused by mining height. Based on the reasonable determination of the mining height during the initial mining stage of Guojiawan 51208 working face, the variation of fracture density is used to measure the degradation of overlying rock strength caused by mining height. Theoretical and numerical analysis models of the degradation of overlying rock strength under different mining heights are established, and the influence of mining height on the stability of overlying rock is obtained by combining the parameters of the mining face. The results show that: (1) With the increase of mining height, the rotation angle becomes larger and the thickness of the rock layer loaded by the bearing layer gradually decreases, making the rock layer more prone to rotational deformation and instability. (2) When the advancing length of the working face is less than 50m, the maximum displacement of the overlying rock and the distribution of the plastic zone at the basic top are basically the same for mining heights of 2.5m and 4.0m; When the advancing length of the working face is ≥ 50m, the maximum displacement of the overlying rock at a mining height of 4.0m increases by more than 10% compared to 2.5m, and the plastic zone at the basic top increases significantly. (3) The advance support pressure increases with the increase of mining height, while the initial pressure step distance decreases with the increase of mining height. The initial pressure step distance for a mining height of 2.5m is around 70m. (4) The initial mining height of 2.5m is adopted, and the mining height is gradually adjusted to the actual coal thickness (4.0m) after the first pressing of the old roof, making the initial mining of the working face more efficient and safer. The above research results are expected to provide reference for the control of the roof in the initial mining of the working face.
- 1
Simulation and analysis of stability and dynamics of walking mechanism of mine unanchoring robotAbstract:
The mine anchoring robot is a kind of high-end robot equipment specially used for the anchorage operation in coal mine mining roadway. Compared with the traditional unanchoring equipment, the unanchoring robot has the advantages of high automation, good safety and high efficiency. In order to enable it to pass through the narrow space between the single pillars flexibly and safely, the fuselage width of the unanchoring robot is very limited, but the operating radius of the unanchoring robot arm is relatively large, which makes the overall stability of the unanchoring robot and the design of the walking mechanism face challenges. In view of the above problems, considering the working conditions, structural composition and working principle of the unanchoring robot, the whole machine model was established by using three-dimensional software SolidWorks, and the change curve of the center of gravity position of the whole machine and the anchor breaking robot arm under different positions and poses was completed in ADAMS, and the permissible range of the center of gravity change of the whole machine under the safety constraints of the equipment was determined. Secondly, the main structure design and key parameter calculation of the track walking mechanism are completed. The accurate positioning of the center of gravity makes it possible to accurately calculate the driving force of the track walking mechanism. Finally, dynamic simulation analysis was carried out in ADAMS under forward and turning conditions. The results show that no matter the robot is moving forward or turning, the force between the track and the driving wheel change similarly in the three directions, and the vertical distribution is approximately sinusoidal, and the force in turning is 2-3 times that in moving forward. The study can provide theoretical basis and technical support for the research and development of mine unanchoring robot.
- 1
Research on the application of low-temperature fluorspar collector CK-1 in Chengde fluorspar mineAbstract:
In order to solve the problem of insufficient collection capacity and poor low-temperature resistance caused by poor water solubility and dispersibility when a 600 t/d fluorite concentrator uses oleic acid as a collector in winter production in Chengde, the slurry needs to be heated to above 20°C. , leading to problems of high production costs and energy consumption; a new low-temperature fluorspar collector CK-1 was developed by using oleic acid with different high and low iodine values to be sulfonated and compounded-saponified-emulsified. At room temperature in summer, Compared with the original production index, the recovery rate of fluorspar concentrate increased by 0.77%. When the slurry temperature was 12°C in winter, the mineral processing index was obtained when the original summer production slurry temperature was 25°C, reducing the heating cost by 11.03 yuan/ton of raw ore, realizing flotation without heating in winter in the dressing plant, and achieving economic benefits. Significantly; the fluorite mines in Chengde area are mainly quartz-type fluorite with similar ore properties, The annual heating cost for winter production of fluorite in northern China is about tens of millions of yuan, and CK-1 has good promotion and application value in the northern region.
- 1
Study on Optimization of Stope Structural Parameters in Mining with Cut and Fill for Gently Inclined Thick OrebodyAbstract:
Taking the backfilling stope of gently inclined thick orebody below the level of Chengchao Mine -675m as the research object, the two-step stoping of the target orebody is carried out by means of sublevel rock drilling followed by backfilling, so as to explore the influence of the span of different mine houses (pillars) on the stope stability. Three numerical simulation research schemes with different spans are formulated according to the theoretical analysis results, and the stope of different mine houses (pillars) with different spans is simulated and studied by using FLAC3D software. Based on the FLAC3D numerical simulation results, the stress, displacement and plastic area distribution of each scheme are compared and analyzed, and the optimal scheme is determined when the span of mine houses (pillars) is 15m. In order to evaluate the stability of the stope with a span of 15m, the monitoring data of vertical subsidence in the stope process are analyzed and sorted. The results show that the slope of the monitoring points near the important buildings (structures) on the roof is 0.77 mm/m, the curvature is 0.032mm/m2, and the horizontal deformation is 0.161mm/m.
- 1
Research on the Quality Evaluation Model of Deep Mine Rock Mass Based on Moment Estimation Theory-Partial Ordered SetAbstract:
In order to improve the reliability of rock mass quality evaluation in deep well mines and overcome the controversial drawbacks of indicator weight assignment in traditional evaluation models, five influencing factors were selected to construct a rock mass quality evaluation system. With the help of moment estimation theory, a reasonable descending sequence of indicator weights was obtained. Partial order sets were introduced into rock mass quality grading, and a comprehensive evaluation model for underground mine rock mass quality based on moment estimation theory partial order sets was proposed. Using 12 typical rock samples as sample data, the model was tested and compared with the results of matter element extension, uncertain measurement evaluation, and actual state. Finally, the model was applied to the quality assessment of a copper iron ore rock mass in Anhui Province. Based on the judgment results, a support scheme suitable for the rock mass stability classification was selected. The results show that the rock mass quality assessment based on moment estimation theory partial order set is consistent with the field investigation, and the optimized support scheme can effectively control the deformation of the roadway, verifying the feasibility of the model in rock mass quality assessment.
- 1
Optimization of Slurry Pipeline Transport Parameters for Mine Backfill Under Variable Filling GradientsAbstract:
Abstract: Advancements in exploration theory and equipment have significantly enhanced mine reserve expansion. However, adapting new resources in the deep periphery of mines to existing production systems requires reassessment, especially as sustainable stoping-and-filling operations face challenges from varying filling gradients and existing slurry transport parameters that no longer meet practical demands.To address these challenges, laboratory tests are conducted on the particle size distribution and slurry flow performance of backfill materials at the mine. Results identify an optimal slurry concentration range of 70%–72% by mass. Theoretical calculations assess the compatibility of current backfill system design with the filling gradients, establishing that a 70% slurry concentration supports a maximum self-flow filling gradient of 9.31, while 72% supports 5.56. To validate these findings, simulation models I (gradient 5), II (gradient 7), and III (gradient 9) demonstrate agreement with theoretical expectations. The results confirm that a 72% slurry concentration is suitable for self-flow backfill in older mine zones with filling gradients of 2.3–4.9, while reducing concentration to 70% enables self-flow in high-gradient (7.2–8.7) goafs in newly developed zones.For optimal technical and economic performance, we propose two strategies: (1) implementing additional pumps to transport 72% slurry under pressure, and (2) utilizing 70% slurry for gravity flow. A comparative analysis shows that the second strategy, which avoids technological modifications, offers a more reliable process and reduces operational costs by RMB2,334,500 compared to the first strategy. Therefore, the second strategy is the preferred option.
- 1
Application research of micro rock drilling rig in the shrinkage mining of sharply inclined thin ore veinsAbstract:
In response to the problems of large mining range, high ore impoverishment rate, low mechanization degree, and high safety risks in the short-hole shrinkage method for steeply inclined thin ore veins in China, combined with the occurrence conditions of a certain metal mine in China, a mechanized short-hole shrinkage method process was proposed, and the mechanized mining idea of using micro rock drilling rigs to drill shallow holes upwards was determined. Firstly, based on the operating conditions of the experimental mining site, the design principles and main technical parameters of the micro rock drilling rig were determined. Secondly, the whole machine adopts a modular and 4-degree-of-freedom rock drilling positioning design scheme, and calculates and simulates the passability, rock drilling positioning, machine stability, and in-situ steering drive system of the micro rock drilling rig in narrow and complex environments. The results show that this scheme can meet the requirements of rock drilling operations in narrow spaces. The experimental results show that the micro rock drilling rig can meet the practical engineering applications of narrow space transition driving, rock drilling positioning, and visual distance remote control operation in the mining of steeply inclined thin ore veins using short-hole shrinkage method.
- 1
Safety Performance Evaluation of Non-Coal Underground Mines Based on ANP-TOPSISAbstract:
In order to evaluate the effectiveness of the implementation of safety management in non-coal underground mines, a safety performance evaluation index system for non-coal underground mines was established, including 6 first-level indicators and 30 second-level indicators, and a safety performance evaluation method for non-coal underground mines based on ANP method and TOPSIS method was established, and the weight of evaluation indicators was determined by ANP method. Combined TOPSIS method to conduct comprehensive evaluation, and finally take XD Company as an example to conduct empirical research. The results show that the most important index affecting the safety performance of non-coal underground mines is mining, accounting for 0.094; XD company has the highest safety performance score in 2023, and its safety performance is level II, with an average annual increase of 5.66% in the comprehensive safety performance score from 2020 to 2023. XD company's safety management is relatively good in safety education and training, but relatively weak in risk classification control and hidden danger investigation and management. The research results have important reference significance for the internal safety management performance evaluation of enterprises, and can provide correct guidance for the safety management of non-coal underground mines.
- 1
Research Progress of Grinding Aids in Iron Ore Grinding FieldAbstract:
China's iron ore resources are abundant, but showing poor, fine, miscellaneous characteristics, more than 98% of iron ore resources need to be beneficiation processing to be effectively utilized. Grinding operation as a preparatory process for the processing and utilization of iron ore, the subsequent selection index has a pivotal role, but the energy consumption of high steel consumption, low energy utilization, especially fine grinding and ultra-fine grinding, energy consumption is higher, is not conducive to reducing the cost of beneficiation. Adding grinding aids in the grinding process is one of the effective measures to improve grinding efficiency and reduce production costs. By reviewing the current situation of research and application of grinding aids in the field of iron ore milling, the development and application of new grinding aids, the influence of grinding aids on the subsequent operations and the mechanism of grinding aids, it is pointed out that the selection and application of iron ore grinding aids need to be compatible with the nature of the ore and the grinding environment, and that the research on the development of new grinding aids and the influence of grinding aids on the subsequent operations should be strengthened with the aim of providing guidance for the selection and application of grinding aids in the field of iron ore milling. The research on the development of new grinding aids and their influence on subsequent operations should be strengthened in order to provide guidance for the selection and application of grinding aids in the field of iron ore grinding.
- 1
Simulation of Flow Field and Local Resistance of Double-frame Louvered WindshieldAbstract:
The mine ventilation system, as a critical subsystem within underground mining operations, requires precise control of air volume to achieve optimization of the ventilation system. Local resistance is one of the key factors affecting air volume. To investigate the local flow field characteristics of louvered air windows and the relationship between the blade opening angle and the local resistance coefficient, numerical simulation of Computational Fluid Dynamics (CFD) was used, and combined with field measurements, a three-dimensional simulation study was carried out at different wind speeds and different blade angles to gain a deeper understanding of the performance and optimization potentials of the air windows. The following conclusions were drawn: when the blades are opened at 45°, the high-speed flow field is gradually formed at the inlet of the wind window, and with the increase of the wind speed at the inlet, the peak wind speed and the flow field area of the flow field are increased; when the blade angle is increased from 60°to 90°, the local resistance at the wind window is reduced, and the distribution characteristics of the flow field at the back are changed; the static pressure energy and the kinetic energy are converted into each other during the process of the wind flow passing through the wind window, the vortex formed in the pressurized and decelerated region and the back wind side of the wind door are also changed; the vortex formed at the backwind side of the wind window is also changed. The vortex region formed on the back wind surface becomes the key factor affecting the local resistance and energy loss in the flow field behind the shutter. In addition, the relationship between the local drag coefficient of the windshield and the opening angle of the blades is analyzed by nonlinear fitting, which shows a power function correlation.
- 1
Study on optimization of point column parameters under artificial roof of a copper mineAbstract:
The stope structure parameters of the mine are important factors to ensuring safe and efficient mining. With the background of the I ore body of a copper mine in Yunnan Province, four different point column sizes were formulated by engineering analogy method, and the displacement and stress of the stope under different point column sizes were analyzed by FLAC3D numerical simulation software. The analysis results show that the most reasonable point column size is 5 m × 6 m ; when the excavation is to the fourth layer, The point column schemes of 4 m×6 m and 5 m×5 m exceed the maximum tensile stress capacity of the mining site, and the two schemes are excluded. The tensile stress of 5 m × 6 m and 6 m × 6 m mining sites did not reach the limit state, but the optimization effect of rectangular point column was significantly better than that of square point column. Finally, the reasonable point column size was determined to be 5 m × 6 m, which provided a good guidance for the stope test of the mine.
- 1
Research on the evaluation method of the effect of low-carbon ecological construction in mines and analysis of key influencing factorsAbstract:
In order to objectively evaluate the low-carbon ecological construction effect of mines and promote the coordinated development of economic construction and environmental protection of mining enterprises, an evaluation index system for the low-carbon ecological construction effect of mines was established based on the idea of DPSIR, and the index weight algorithm of DPSIR-DEMATEL-AHP was constructed by using the DEMATEL method and AHP method to objectively revealed the close degree connection among the driving force of mining enterprise development, ecological environment pressure, environmental quality status of mining areas, the impact of mining on the environment and the response of mining enterprises, also better quantitatively describes the ambiguity and uncertainty of the subjective opinions of the expert group on the relative importance of each indicator. Using the interval number distance algorithm and the binary connection number optimal algorithm, a method for evaluating the effect of mine low-carbon ecological construction based on interval number goodness is established, which provides an effective method for objectively evaluating the low-carbon ecological construction effect of mine and analyzing the key factors affecting mine low-carbon ecological construction. The model method was used to evaluate the low-carbon ecological construction effect of open-pit mine and analyze its key influencing factors. The results showed that the low-carbon ecological construction effect of the mine in 2021 was the best while the low-carbon ecological construction effect in 2020 was the worst. Important measures to improve the effectiveness of low-carbon ecological construction in mines include enhancing the mining profit margin, saving energy and increasing efficiency in mines and reducing the CO2 emissions, enhancing the solid waste utilization per unit of industrial output value, increasing the greening coverage rate in mining, implementing effective dust-reducing measures, strengthening the management of key work processes in mine production, and enhancing the coverage rate of energy-saving and emission-reduction campaigns and training and so on.
- 1
Experimental Study on Fine Grinding and Deep Beneficiation Tailings Flotation of Ilmenite from Fine-Grained Iron ConcentrateAbstract:
The study focuses on the finely ground and deeply selected tailings of fine-grained iron concentrate provided by a factory in the Panxi region. The TiO2 grade is 19.51%, and the main gangue minerals are pyroxene, chlorite, and amphibole. Based on the characteristics of the ore, BY series inhibitors have been developed. The results showed that using MOH as the collector and BY-3 as the inhibitor, through a closed-loop process of "one coarse, one fine desulfurization one coarse, one sweep four fine, and returning the intermediate ore in sequence for titanium selection", a titanium concentrate yield of 30.98%, a TiO2 grade of 46.94%, a recovery rate of 74.54%, and a flotation tailings TiO2 grade of 5.27% could be obtained. The research results of this paper can provide technical references for efficient recovery and utilization of similar ores.
- 1
Influence of mineral composition on crack propagation and static properties of graniteAbstract:
In order to study the effect of mineral composition content on Microcrack propagation and static mechanical parameters of granite. Combined with the thin section identification analysis and PFC2D method, a numerical model considering the mesoscopic composition of rock was established. The mesoscopic parameters of the model were calibrated by static uniaxial compression tests. The influence of mineral component content on Microcrack propagation, compressive strength, and elastic modulus of granite was discussed. The results show that: the elastic modulus is negatively correlated with potassium feldspar and plagioclase, and positively correlated with quartz and biotite; Biotite has the greatest influence on compressive strength, followed by plagioclase, then quartz, and the least influence is potassium feldspar; In addition, with the increase of quartz content, the failure mode changes from "y" shear failure to "X" shear failure. With the increase of potassium feldspar content, the failure mode changes from oblique section shear failure to "X" type shear failure; with the increase of plagioclase content, the failure mode changes from "V" type shear failure to "X" type shear failure; biotite has the greatest influence on the failure mode. With the increase of biotite content,the failure mode changes from "V" cross shear failure to monoclinic shear failure, and then to compound shear failure. Furthermore, stiffness heterogeneity factor (SHF) is introduced to establish the relationship between mineral composition and rock mechanics parameters,The linear relationship between peak stress and elastic modulus and stiffness heterogeneity factor is obtained。
- 1
Abstract:
To improve the performance of biological detention facility and expand the resource utilization of vanadium-titanium magnetite tailings, these tailings as a substrate amendment in biological detention facility are employd by the research. Feasibility and pollutant removal effectiveness of using vanadium-titanium magnetite tailings as an amendment for the substrates of bioretention facilities is explored. The results indicate that the leaching toxicity of the four main heavy metal ions(Cr、Mn、Zn、Cu) in the tailings is below the standard limitations. The adsorption of TP, NH3 and NO3--N by the amended substrate follows the Freundlich adsorption isotherm model and is controlled by both film diffusion and intraparticle diffusion, TP and NH3 adhere to the pseudo-second-order kinetics equation, while the adsorption of NO3--N is mainly dominated by physical adsorption.. Compared with planted soil and sand substrates, the removal rates of TP, NH3, and NO3--N in the effluent were 97.2%, 91.4% and 70.5%, respectively,?
- 1
Exploration into the Origin of Groundwater and Fault Water Sources in the Huibaoling Iron Mine AreaAbstract:
In order to reveal the hydrochemical characteristics and causes of groundwater at different burial depths in the Huibaoling iron mine area, and analyze the sources of deep fault water supply, a total of 37 groundwater samples were collected and tested, including fracture water from the Liguan Tongjiazhuang Formation, karst fracture water from the Erqingshan Formation, metamorphic rock fracture water, and fault water. Statistical analysis, Piper trilinear diagram, Gibbs diagram, and ion combination ratio method were used to explore the characteristics and causes of groundwater hydrochemical components in the area, as well as the sources of fault water supply. The results showed that the TDS of groundwater in each layer increased significantly with increasing burial depth, and The dominant anions and cations gradually evolved from HCO3- and Ca2+to SO42-, Cl-, and Na+; The hydrochemical components show clear zoning in Piper trilinear diagrams, Gissb diagrams, and other graphs, with significant differences in groundwater types and TDS between each layer, and poor hydraulic connections between each aquifer. The research results indicate that the formation of groundwater chemical components in the fracture water of the Liguan Tongjiazhuang Formation and the karst fracture water of the Erqingshan Formation is mainly controlled by rock weathering, and the ion components mainly come from the dissolution of carbonate, sulfate minerals, and salt rocks; The fissure water in metamorphic rocks is controlled by evaporation and concentration. Na+and K+come from the dissolution of silicate minerals and the alternating adsorption of cations, while Ca2+, Mg2+, HCO3-, and SO42- mainly come from the dissolution of carbonates and sulfates and the oxidation of pyrite; The fault water is influenced by both rock weathering and concentration, and its main source of supply is the fissure water of the upper Liguan Tongjiazhuang Formation and the karst fissure water of the Erqingshan Formation. It is also subjected to ion adsorption exchange and pyrite oxidation dissolution similar to metamorphic rock fissure water.The research results provide reference significance for the prevention and control of mine water hazards.
- 1
Study on Coal Gangue Filling Technology Scheme in Xinjietaigemiao Mining AreaAbstract:
Coal gangue filling is an environmentally friendly goaf treatment method. Coal gangue is used as filling medium to reduce environmental impact and improve the comprehensive utilization rate of resources. In this study, according to the specific geological and production conditions of the Taigemiao mining area in Xinjie, a variety of gangue treatment technologies were compared and analyzed, and the filling technology was determined as the preferred scheme. A set of comprehensive filling technology scheme is proposed, which covers the key links of material preparation, transportation, filling and curing, and ensures the geological adaptability, production feasibility and environmental friendliness of the scheme. The results show that high-level grouting is the preferred filling mining scheme, and a full set of filling technology including gangue crushing and storage, mixing ratio, pumping system and pipeline system is designed. Through the analysis of operating costs, the feasibility and advantages of the scheme in both technical and economic aspects are confirmed. The implementation of the filling scheme is expected to achieve the dual benefits of environmental management and safe production in the mining area and promote the sustainable development of the mining area.
- 1
Study on the Effect of Flotation Concentration on the Flotation Efficiency of High Calcite FluoriteAbstract:
To investigate the effect of flotation concentration on the flotation efficiency of high calcite type fluorite, under the condition that the grinding fineness is -0.074mm and the content accounts for 70%, slurry concentration experiments were conducted in the stages of coarse selection, sweep selection, selection, fine coarse selection, and fine sweep selection to systematically study the influence of different flotation concentrations on fluorite recovery rate and grade. The experimental results show that a suitable flotation concentration can significantly improve the grade and recovery rate of fluorite, especially in the roughing stage. In response to the problem of high calcite content and susceptibility to mudification, the flotation process was optimized by controlling the flotation concentration, combining fine and coarse selection with fine sweeping selection. This reduced the circulation of intermediate ore and improved resource utilization efficiency. Under optimal conditions, a closed-circuit test obtained fluorite concentrate with a CaF2 grade of 97.84% and a recovery rate of 85.97%. The research results emphasize the importance of flotation concentration in improving flotation efficiency, providing practical guidance and theoretical support for similar fluorite beneficiation processes.
- 1
Mine Fire Smoke Object Detection Based on Improved YOLOv10sAbstract:
Mine fire smoke target detection is one of the important preventive measures to prevent fire accidents in mines. In order to improve the accuracy and speed of fire smoke detection in mines, a mine fire smoke target detection scheme based on improved YOLOv10s is proposed. Firstly, the collected mine fire smoke image dataset is made into training set, validation set and test set according to 7:2:1 through the online annotation platform. Before training, the images are subjected to wavelet denoising and Auto-Msrcr algorithm enhancement; then the original YOLOv10 loss function is reconstructed using Focaler-IoU, and the attention module CBAM that strengthens the performance of convolutional neural networks is added, and the third C2f module in Neck is replaced by the cross-stage partial network module VoV-GSCSP, thereby improving the representation ability and decision-making performance of the model, and finally improving the feature weight of mine fire smoke recognition. The experimental results show that the improved YOLOv10s model has a 3.4% higher accuracy P than the original model, and the average precision mAP@50 and mAP@50-95 are increased by 0.6% and 2.2% respectively, and the detection frame rate is increased by 11.9 frames; compared with some previous mainstream YOLO models, the improved YOLOv10s model has higher detection accuracy and speed, and the accuracy P, average precision mAP@50-95 and detection frame rate are higher than some previous mainstream YOLO models. The improved YOLOv10s model has good comprehensive detection performance and can be used in mine fire smoke detection scenarios that require high accuracy and high real-time performance.
- 1
Study on the sedimentation and separation laws of coal particles in the waste oil-water biphasic systemAbstract:
To explore the feasibility of utilizing waste oil for the separation of difficult-to-float coal slurry, focusing on coal particles of -0.5 mm, the sedimentation behavior of coal particles in oil, water, and oil-water interfaces was systematically investigated through different medium wetting treatments. The sedimentation process of coal particles in the liquid was observed and recorded com-prehensively to understand their sedimentation characteristics, and with the aid of image processing software, the sedimentation velocity of coal particles upon reaching the oil-water interface was determined. Meanwhile, through the final sedimentation results of coal particles and force analysis, the conditions for the sedimentation and separation of coal particles in waste oil and water were further determined. The influences of coal particle ash content, particle size, and different medium wetting treatments on the sedimentation and separation behavior of coal particles at the oil-water interface were systematically studied. Experimental results indicate that the sedimentation and separation results of coal particles at the oil-water interface are positively correlated with the square of the coal particle size and density, and negatively correlated with the dynamic equilibrium force of the oil-water interface. Coal particles treated with water wetting exhibit different sedimentation states, while those treated with oil wetting and drying remain suspended at the oil-water interface. Water wetting treatment allows coal particles to adhere water on the surface, reducing the dynamic equilibrium force between coal particles and the oil-water interface, achieving particle sedimentation and effective separation. Furthermore, by replacing waste oil, the conditions for the sedimentation and separation of coal particles in waste oil and water were further verified. This study provides new insights and theoretical support for the efficient separation of coal slurry using waste oil.
- 1
Visualized experimental study on the frozen seepage flow properties through rock fractures under low temperatureAbstract:
Both rock slope instability and tunnel collapse disasters in cold areas are involved by the frozen seepage flow problems in rock fractures．In order to explore the evolution mechanism of the frozen seepage for rock fractures at low-temperature，a visualized experiment platform for frozen seepage for fractures under low-temperature conditions was developed，and a series of frozen seepage experiments in fractures for different flow rates were carried out．Based on the image-processing technology，the dynamic development process of liquid-ice phase transition was quantified，then the relationships between the liquid-ice phase transition and the frozen seepage flow properties were analyzed，The research results show that due to the difference in heat exchange intensity between liquid phase and fracture surfaces，the liquid phase is frozen firstly in the upper and lower regions of fracture outlet in the frozen seepage process．With the development of frozen seepage，the areas of glacial phase increase gradually，and the seepage channel decreases accordingly，which results in the growth of the liquid-phase flow rate and an intensification of thermal convection intensity under constant flow rate conditions，so that the ice-ablation phenomenon occurs continuously at the convex places of the ice phase on both sides of fracture．When the frozen seepage reaches a steady state，the Reynolds number of liquid-phase flow is obviously greater than its initial value，and the pressure gradient is roughly linear with the flow rate at this point，furthermore the larger flow rate of liquid-phase has a significant inhibitory effect on the freezing rate of ice-phase．
- 1
Key rare earth demand and new quality productivity development path of China's electric vehicle industryAbstract:
In the context of clean energy economic transformation, in order to alleviate the imbalance between supply and demand of some key rare earth metals at the development of electric vehicle industry, The Gompertz model and material flow analysis method were used to forecast the theoretical demand of electric passenger vehicles in China from 2024 to 2050, set three rare earth demand scenarios, discuss the recovery rate of rare earth resources at 60%, and considere the use factors of hybrid vehicles. The results show that under the given scenario that remains consistent with the current level of motor technology innovation, the supply of rare earth metals neodymium and praseodymium will be sufficient until 2050, but the dysprosium and terbium metals will have a serious supply-demand imbalance. But in the semi-rare-earth and radical scenarios with a higher degree of motor technology innovation, dysprosium will achieve the supply-demand balance before 2043 and 2039 respectively, and terbium will reach the sufficient-supply goal in 2041 and 2031 respectively; compared with the normal situation without considering recycling, recovery rate at 60% of rare earth resources will reduce the output of restricted electric vehicles by 79%, and due to the low use of rare earths in the electric motors of plug-in hybrid vehicles, they are also taken into consideration. Therefore, based on the whole rare earth industry chain, upgrading the mining and recycling technology of rare earth resources in the front end of the industry chain, increasing the innovation of rare earth motors and alternative motor technologies in the middle part of the chain, innovating and promoting the application scenarios of low rare earth content motors in the application part of the chain are necessary, so as to systematically categorize and integrate the chain with three parts into two effective ways, which are the innovation of motor technology and comprehensive utilization of resources, then to promote the development of new quality productivity that will solve the problem of imbalance supply-demand of some key rare earth metals.
- 1
Determination of the location of lower wall link roadway by sublevel caving without pillar under dynamic responseAbstract:
In order to ensure the safe recovery of the ore body under the bottomless pillar segmental avalanche method, and to avoid the instability of the lower coupling lane due to the blasting vibration of the ore body during the mining process, the first subsection of a nickel mine was taken as the research object, and numerical simulation was carried out by using FLAC 3D to determine the position of the lower coupling lane under the bottomless pillar segmental avalanche method under the dynamic response. The results of the study show that when the segment height is 15 m, the velocity, displacement and stress of the roadway mass points are integrated, and the safe distance from the retreating position is 12 m. The engineering practice shows that the safe distance derived from the study is highly in line with the reasonable safe distance of the roadway in the mine site, and it can provide ideas and technical support for the solution of the similar problems in the mines.
- 1
Comprehensive Recovery Test of a Silver-bearing Polymetallic Ore with High Fe, Mn, Low Pb and Zn in Heilongjiang ProvinceAbstract:
The contents of silver, lead, zinc, iron, manganese and sulfur in a polymetallic mine in Heilongjiang are 330.52 g/t, 0.57%, 0.29%, 25.77%, 9.05% and 3.38% respectively. The ore has high iron and manganese contents, high carbon content, low lead and zinc contents, complex mineral embedding relationships, and silver, lead and zinc are partially wrapped in iron and manganese minerals, which makes it difficult to guarantee the concentrate grade and recovery rate. In order to achieve comprehensive recovery of valuable components in the ore, the process of "silver-lead-zinc mixed flotation-iron-manganese magnetic separation" is adopted. The closed-circuit test of the whole process can obtain the mixed silver-lead-zinc concentrate with silver, lead and zinc grades of 3010.80g/t, 5.39% and 2.37% respectively, and the recovery rates are 83.35%, 89.61% and 77.55% respectively. The iron grade and recovery rate of iron concentrate are 60.97% and 8.01% respectively, the recovery rate of magnetic iron is 79.05%, and the manganese grade and recovery rate of manganese concentrate are 18.30% and 76.38% respectively. The tailings yield of the whole process is 50.23%, and the silver, lead and zinc grades are 35.07g/t, 0.055 and 0.068% respectively. The comprehensive recovery of silver, lead and zinc is realized by using copper sulfate as activator and sodiumO-butyldithiocarbonate + Benzenemethanamine as collector in the silver, lead and zinc bulk flotation, and the backwater can be reused in production.
- 1
Research on mechanical properties and optimal proportion of grouting materials based on orthogonal testAbstract:
In order to study the mechanical properties and optimal ratio of carbon nanotube-modified superfine cement-based grouting materials, carbon nanotubes, superfine cement, dispersant, defoamator and polyacrylate emulsion were used as raw materials based on three-factor and four-level orthogonal test, and the water-cement ratio and the content of carbon nanotubes and polyacrylate emulsion were used as control factors. The viscosity, fluidity, setting time and uniaxial compressive strength of the grouting slurry were tested. The influence of each factor on each index was determined through range analysis and variance analysis. The uniaxial compressive strength and elastic modulus were selected as the index for coupling, and the coupling value was analyzed by range, variance and multiple linear regression to obtain the optimal ratio and verify it. The results show that the uniaxial compressive strength and elastic modulus of the test block decrease with the increase of the water-cement ratio. With the increase of carbon nanotube content, the uniaxial compressive strength of the test block increases first and then decreases, and the elastic modulus increases-decreases-increases. With the increase of polymer content, the uniaxial compressive strength of the test block increases first and then decreases, and the elastic modulus decreases monotonously. After the uniaxial compressive strength and elastic modulus of the test block are normalized, the weight of 0.6:0.4 is added and coupled, and the optimal combination of grouting materials is obtained by range and variance analysis. Through multiple regression analysis and laboratory test verification, the optimal ratio is water-cement ratio: carbon nanotube content: polymer content =0.8:0.4%:2.5%. The experimental results can provide some technical support for the optimal ratio of carbon nanotube modified superfine cement-based grouting materials.
- 1
Study on erosion wear characteristics of valve gap flow field in poppet valve filling pumpAbstract:
In view of the problem that the taper valve is easy to wear during the working process of the taper valve filling pump,Using the Navier-Stokes and k-ε two-equation turbulence model and the erosion wear model of valve gap two-phase flow,Based on computational fluid dynamics (CFD) software, a total of 13 groups of different taper angles from 30° to 90° were established to calculate the gap flow field of the taper valve. The simulation and erosion wear characteristics of the taper valve gap flow field with different taper angles were studied. The effects of particle mass fraction, particle diameter and taper Angle on the gap wear of the taper valve were analyzed.The results show that the maximum flow velocity of the valve gap field is 8.28m/s near the bottom Angle of the valve and the valve gap.The maximum flow velocity and its threshold range of the valve gap flow field decrease with the increase of the cone Angle of the valve. When the cone Angle increases from 30° to 90°, the maximum flow velocity decreases from 28.698m/s to 6.766m/s, which decreases by 76.42%.The wear of tailing sand particles on the taper valve mainly occurs at the edge of the end face of the taper valve disc, and the erosion wear area is dispersed at the edge of the valve disc. The maximum erosion rate is 9.4×10-4kg/m2s, and the abrasive wear is concentrated at the edge of the valve disc face, and the maximum erosion rate is 1.83×103kg/m2s.The industrial verification shows that choosing 60° as the design Angle of the taper valve can effectively increase the service life of the taper valve and improve the stability of the taper valve filling pump.
- 1
Study on the mechanism of rapid flocculation and sedimentation of fine tailing sand under ultrasonic infusion effectAbstract:
In order to explore the method of accelerating the flocculation and sedimentation speed of fine tailings, ultrasonic technology is introduced into the tailings flocculation and sedimentation, and the non-contact acoustic field and micro-vibration without destroying the internal structure of the settled tailings are applied to the tailings slurry medium. Ultrasonic conduction-based fine tailings flocculation and sedimentation test is carried out to analyze the changes of tailings slurry solid-liquid surface settling under the application of 28kHz, 100W ultrasonic transducers for different time periods. Combined with the simulation of flow field in thickener, a theory of thickener settling under ultrasonic conduction is uncovered. The result is showed that applying ultrasonic under different time periods , the solid-liquid surface of the tailings slurry changes faster than the natural flocculation and sedimentation, and the maximum change amplitude is more than 70%. Also there is a tendency of colloidal flocculant and small flocs to move upward in the interface of solid-liquid surface, which provides excessive floc environment for the subsequent continuation of flocculation and sedimentation of tailings slurry. ultrasonic conduction not only facilitates the flocculation and sedimentation efficiency under the current environment, but also has a positive effect on the flocculation and settling efficiency under the current environment. Continuous flocculation and sedimentation is potentially advantageous.
- 1
Research on the development of domestic filling pipeline transportation based on visual graph analysisAbstract:
In order to clearly show the development process of slurry conveying and comprehensively analyze the focus of transportation research at different stages, the bibliometric analysis tool CiteSpace software was used to conduct co-occurrence analysis and cluster analysis of 494 articles included in CNKI Literature Database from 2006 to 2023. Most of the research subjects focus on experts such as Zheng Bokun, Gan Deqing, Guo Lijie, and Gao Qian, and the distribution of stars is presented, and the research perspective has limitations. The research content focuses on the discussion of material preparation, conveying technology, and stope filling, in which the slurry ratio has been expanded from focusing on the particle size distribution of tailings to the application of admixtures, and the integration of various disciplines has been enhanced. In the future, it is necessary to strengthen the core position of relevant mining research institutions, attach importance to cross-institutional collaboration and exchanges, expand the research group constructed, refine the research scope of pipeline transportation, strengthen the research on filling materials, deepen the depressurization treatment of deep well transportation, try to integrate non-Newtonian fluid research methods, and enrich the research in the field of filling pipeline transportation in the domestic academic circles.
- 1
The Influence of Fe(Ⅲ)-O/OH and CN? on Lead Adsorption onto Pyrite SurfaceAbstract:
To elucidate the mechanism of how pyrite oxidation products and residual CN? influence the adsorption of lead-containing ions on pyrite surface. Pyrite with varying degrees of oxidation were prepared through chemical oxidizing, together with solution chemistry calculations, quantitative and qualitative analysis of surface products, electrochemical impedance spectroscopy (EIS) and Zeta potential measurements methods, the mechanisms by which Fe(III)-O/OH formed upon oxidation and residual CN? affect lead adsorption were studied. The results showed that the primary driving force for the physical adsorption of lead on the pyrite surface is the electrostatic attraction between positively charged lead-containing ions and negatively charged ions on the pyrite surface. Fe(III)-O/OH increases the positive charge on the pyrite surface, reducing the amount of negative charge and thereby decreasing the electrostatic driving force for lead adsorption. However, CN? can chemically react with Fe(III)-O/OH to form Fe(CN)3, which removes Fe(III)-O/OH, ultimately increasing the electrostatic adsorption force between positively charged lead-containing ions and oxidized pyrite. This study reveals the mechanisms by which Fe(III)-O/OH/CN? decreases/increases lead adsorption, providing new theoretical foundations for the efficient recovery of gold from low-grade gold-bearing pyrite and lead and cyanide pollution control.
- 1
Open-pit Bench Based on Column Charge Blasting Crater Test Study on Optimization of Blasting ParametersAbstract:
Utilizing the theory of column charge blasting crater as a foundation, and adhering to the similarity criterion, a field experiment was devised to investigate the formation of column charge blasting craters. In a large open-pit coal mine in Inner Mongolia, a cylindrical charge with geometric similarity to the actual production column was made by using emulsion explosive cartridge and PVC pipe. The single hole variable hole depth and variable hole distance blasting funnel tests were carried out respectively. By drawing the 、 、and curves, the elastic deformation energy coefficient, the best depth ratio, the best buried depth, the reasonable buried depth, the reasonable hole spacing and other blasting basic parameters under the test conditions are obtained. According to the characteristics of the square root similarity law of the column charge, the optimal row spacing of the coarse sandstone step with 250 mm aperture is 6.53 m, the reasonable row spacing range is 6.19 m ~ 6.53 m, and the reasonable hole spacing is 9.98 m ~ 12.48 m. The field application results show that the cylindrical charge blasting funnel test carried out in the blasting site can provide guidance for the optimization of blasting hole network parameters.
- 1
Stability control of a large-section chamber in a deep shaft at Jinchuan No.2 MineAbstract:
With the gradual reduction of shallow mining resources, mining is moving deeper and deeper, and the increase in mining height has made it difficult to control the perimeter rock and increase the cost of support in the large section chambers, so in order to ensure the stable operation of the 941 m mixer chamber complex, a study was carried out to control the stability of the perimeter rock in the large section chambers. In this paper, laboratory testing, numerical simulation and field monitoring were used to optimize the construction process and support design. It was found that the chamber was most stable when excavated in the order of batcher chamber, mixer chamber, and cement silo chamber first, then orthogonal design experiment was used to select the best support design. The initial support of anchor mesh spray+grouting anchor and the joint support of cast-in-place reinforced concrete+anchor cable were proposed, and the deformation of the surrounding rock was effectively controlled during the on-site support.
- 1
Experimental study on comprehensive recovery process of copper sulfur from a complex borniteAbstract:
A complex porphyry copper-sulfur raw ore contains 0.45% copper and 3.61% sulfur, which has high development and utilization value. But it is difficult to make efficient use of this resources, due to the characteristics of diverse ore structure, diverse copper species, easy slime of gangue minerals and uneven grain size distribution of target minerals. Based on the mineralogical result, the the flotation process flow of coarse grinding of raw ore - mixed flotation - regrinding of coarse concentrate - copper-sulfur separation was confirmed after flotation scheme comparison tests. Copper concentrate with copper grade of 25.145% at a copper recovery rate of 90.90%, sulfur concentrate with copper grade of 0.185% at a copper loss rate of 2.13%, sulfur 42.51% at a sulfur recovery rate of 66.24%, were obtained under small closed-circuit test by using copper collectors as GTB1 and GTB3 which have good selectivity properties. The process adopts green and efficient chemical system and reasonable process flow to realize efficient comprehensive recovery of copper and sulfur. This study can provide a basis for the maximum utilization of these resources.
- 1
Study on Efficient Mining Method and Stope Structure parameter Optimization of Silver Polymetallic OreAbstract:
The upward horizontal slicing mining method was originally used in the Yinjiacun silver polymetallic mine. However, with the gradual deepening of the mining depth and the change of the occurrence state of the surrounding rock of the ore body, a safer and more efficient mining method is urgently needed to improve the economic benefits of mining. According to the mining technical conditions of silver-lead-zinc-copper ore body in the middle section of 3900 m, two mining schemes of upward horizontal layered filling method and downward medium-deep hole sublevel filling method are proposed. The safety, dilution loss rate, mining-cutting ratio, production capacity and economic benefits of the mining method are comprehensively analyzed. Finally, the downward medium-deep hole sublevel filling mining method is selected. At the same time, the numerical simulation method is used to optimize the segmentation parameters of the stope, and the optimal segmentation parameters are obtained. The stage is divided into three segments, which are 18 m, 16 m and 16 m respectively from top to bottom. At this time, the maximum displacement of the hanging wall surrounding rock is 94.11 mm, and the overall displacement of the surrounding rock in the empty area is 50 mm ~ 100 mm, which ensures that there is no obvious penetration failure in the plastic zone inside the filling body.
- 1
Study on meso-mechanical properties and instability mechanism of different joint interface combinations under uniaxial compressionAbstract:
In order to study the micromechanical properties and instability mechanism of rock-concrete composite under uniaxial compression, numerical tests of uniaxial compression under the coupling effect of different joint shapes and joint angles were carried out based on particle flow. The evolution law of strength, deformation parameters and number of micro-cracks of the composite were analyzed, the damage law of energy evolution was revealed, and the instability index of the composite considering energy form was proposed. The results show that the elastic modulus decreases gradually and then surges, showing a U-shaped change, and the peak stress shows a V-shaped change, which decreases first and then increases. With the increase of joint dip Angle, the failure modes of assembly are divided into three types: tensile shear failure, oblique tensile failure and split shear failure. When the joint inclination of the assembly is 90°, the damage parameter D changes the fastest, the damage characteristics of the assembly are the most obvious, and the stability of the sample of the assembly is the worst. Under different joint shapes, when the joint inclination is 0°, 30° and 45°, the damage characteristics of the triangular joint shape sample are the most obvious, and the stability of the sample is the worst. Under different working conditions, the average instability value of concrete-granite composite samples has the same change law, and all of them decrease gradually with the increase of joint inclination Angle. When the rectangular joint inclination Angle is from 60° to 90°, S increases slightly. With the increase of the Angle, the average instability value S of the trapezoid gradually increases. The instability index of the assembly considering the form of energy is put forward. The research results can provide important scientific basis for the stability of tunnel (alley) engineering.
- 1
Study on the Influence of Hybrid Fiber Content on the Comprehensive Mechanical Properties of Tailings Filling BodyAbstract:
In response to the issue of significant loss and dilution during the ore-drawing process in the pillarless sublevel caving method, physical ore-drawing experiments were carried out under different sublevel heights and end wall inclination angles. The variation laws of the drawn-out ore body shape as well as the changing characteristics of the ore dilution rate and recovery rate were obtained. The results indicate that when the sublevel height is fixed, with the increase of the end wall inclination angle, the horizontal thickness of the drawn-out ore body along the drift direction expands, the inclination angle of the flow axis and the axial deviation angle increase, while the width along the end wall surface and the vertical height decrease. During the ore-drawing process, the main source of waste rock shifts from the upper waste rock to the frontal waste rock. Moreover, the larger the sublevel height, the more prominent these characteristics are. The later the waste rock appears, and the more distinct the difference in the growth rate of the cumulative ore dilution rate under different end wall inclination angles. For different sublevel heights, when the end wall inclination angle is 90°, the cumulative ore dilution rate is the minimum at all sublevel heights after reaching the cut-off grade. When the end wall inclination angles are 85°, 90°, and 95°, the ore recovery rate initially decreases and then increases, reaching the minimum values at sublevel heights of 18.8 m, 19.17 m, and 18.73 m, respectively. The ore recovery rate at each sublevel height first increases and then decreases with the increase of the end wall inclination angle, and reaches the maximum when the end wall inclination angle is 85°.
- 1
Research on Intelligent Control System of Belt Conveyor Based on Multiverse Optimization AlgorithmAbstract:
In order to achieve coal flow balance control and intelligent requirements for energy saving and efficiency improvement of the belt conveyor in the 4205 working face of Longquan Coal Mine, this paper establishes a mathematical model of the belt conveyor, optimizes its fuzzy PID controller using the Multi Universe Algorithm (MVO), and simulates the entire belt conveyor using MATLAB. The simulation results are compared and analyzed with the actual data on site. The analysis results show that: (1) Compared with traditional PID control, the MVO algorithm optimizes the fuzzy PID control to reduce its adjustment time and overshoot by 46.66% and 34.49%, and the fitness value from 1022 in the first iteration to 901.8 in the last iteration, indicating that the response speed, stability, and resistance of the controlled object are accelerated, stable, and resistant. Improved disturbance capability. (2) By comparing the actual belt speed of the 4205 working belt conveyor in Longquan Coal Mine with the MVO-FUZZY-PID controlled belt speed within 300 seconds for 5 time periods, it was found that the range of belt speed fluctuations decreased by 39%, 56%, 62%, 63%, and 67%, respectively. The controlled belt speed can more accurately approach the set value and has a better balance effect. (3) Five time periods corresponding to the actual belt speed were selected to analyze the changes in coal flow rate from a power perspective, and it was found that the required power was reduced after MVO-FUZZY-PID regulation. Therefore, the MVO algorithm optimizes the belt speed to achieve energy-saving control and fast matching of coal flow rate.
- 1
Optimization Design of Open Pit Mine Road Based on Truck Fuel Consumption LawAbstract:
In order to reduce the cost of stripping transportation in open pit mines and realize the efficient flow of strippings, the optimal design of open pit mine roads is studied. Firstly, the current situation of the optimal design of open pit mine roads is analyzed, and a method of optimal design of open pit mine roads based on the law of fuel consumption of trucks is proposed.The introduction of the “Fuel Consumption Equivalency Factor”, which maps the fuel consumption of trucks at various gradients, facilitates the accurate estimation of fuel costs; second, based on the truck fuel consumption data measured on site at an open pit mine, the fuel consumption characteristics of trucks climbing with heavy load and descending with no load at different gradients were quantitatively analyzed; finally, for the fuel consumption law of MT3700 model trucks, a combined slope design method was explored by optimizing the slope and slope length of the flat road section, and an optimization strategy for open pit mine roads was proposed.The results show that: ① open-pit mine trucks as far as possible to control the distance within 3.5km, 2km or so for the best distance, beyond 3.5km after the amount of fuel consumption generally increased, and the rate of growth is faster; ② mine road design should be as low as possible to reduce the height of the lift, control in 160m or less, of which the lift height of 80m the highest efficiency of the amount of fuel consumption; ③ mine road gradient is not very sensitive to the amount of fuel consumption, Therefore, the overall slope of the mine transportation road can be appropriately increased to reduce the distance to reduce the consumption of diesel fuel.
- 1
Optimization study of structural parameters of inclined ore body mining area based on ore drawing experimentsAbstract:
In the process of metal mining using the bottomless pillar segmented caving method, the mining site structure is an important factor that directly affects production efficiency, ore loss rate, and dilution rate. This article focuses on the problem of high ore loss and depletion rates in the Kzil Tashtek copper lead zinc polymetallic mine when entering the open-pit and underground joint mining stage. Based on existing engineering conditions and experimental measurements of loose flow parameters, important mining site structural parameters such as drift spacing are preliminarily determined. Then, a self-designed adjustable drift spacing ore drawing model is used to analyze and verify the ore recovery and depletion rates for different drift spacing, and the optimal drift spacing suitable for this ore body condition is selected. The results show that when the distance between the approaches is 18m and the collapse ratio is 3.0m, it can make the height of the collapsed and released ore coincide, which is beneficial for improving the recovery rate of the ore and reducing the dilution rate. The difference in ore return to poverty has increased by about 7 percentage points, indicating that the research method combining optimized structural parameters, ore drawing simulation experiments, and on-site industrial experiments is scientific and effective.
- 1
Experimental study on mechanical properties of paste filling body mixed with calcium carbonateAbstract:
Calcium carbonate can be used as a retarder to improve the flow time of filling slurry. In order to test the influence of calcium carbonate on the mechanical properties of paste filling body, the mechanical properties of paste filling body mixed with retarder calcium carbonate were studied, the single factor and orthogonal method were used to design the filling body material ratio scheme, and the filling body was prepared. The uniaxial compression test was carried out on the filling body specimen, and the acoustic emission change of the filling body during the loading process was monitored in real time. The microstructure of the crack of the specimen was observed by SEM. The influence law and weight order of each factor on the compressive strength of the filling body were studied, and the failure mechanism of the filling body was analyzed from multiple angles. The results show that: 1) With the increase of calcium carbonate mass fraction, the strength of filling body decreases first and then increases. After adding calcium carbonate, the influence of mass fraction of fly ash, cement and solid material on the strength of filling body at different ages (3d, 7d, 28d) is basically the same as that before adding calcium carbonate,calcium carbonate has a weak effect on the deterioration of the compressive strength of the filling body, and the price is relatively low, it can be used as a retarder for filling materials; 2) Based on the range analysis, the weight order of the influence of each factor on the 28 d strength of the filling body is cement mass fraction > calcium carbonate mass fraction > solid mass fraction > fly ash mass fraction; 3) According to the failure characteristics of filling body, with the increase of curing age, the failure mode of filling body changes from ductile splitting to brittle shear failure; 4) The acoustic emission ringing count changed abruptly before and after the initial compaction of the filling body was close to the elastic deformation stage and the peak stress, which revealed the internal damage evolution process of the filling body.
- 1
Optimization of stope structure parameters of "arch bridge method" mining scheme in a gold mineAbstract:
Abstract: Objective: To solve the mining problem of orebody under the main transport lane in the middle section of 790m of a gold mine. Methods: A mining scheme of "arch bridge method" was put forward. Means: The stope top column and intercolumn are simplified into a mechanical model, and the safety thickness of the top column under two constraints is calculated as 7.09m by using the Reissner thick plate theory. The rationality of the "arch bridge method" of 6m thickness isolation intercolumn is verified by using the Bieniawski pillar strength calculation formula. Four kinds of numerical simulation schemes are proposed based on the safety thickness of top pillar calculated by theoretical calculation, and four kinds of mining schemes of "arch bridge method" are simulated by FLAC3D numerical simulation software. Result: Based on the analysis of the results of the stress field, displacement field and plastic zone of the stope, it is determined that the optimal top column thickness of the "arch bridge method" mining scheme is 10m, and the loss rate, dilution rate and ore grade of the "arch bridge method" mining scheme in the subsequent production practice process are similar to those of the stope at the same stage, and the production capacity of the stope is increased by 94.4%. The transportation capacity of 900t/d of the main transportation lane in the middle section of 790m is maintained, which provides a solution to the problem of the same type of mine.
- 1
A fusion improvement of YOLOv7-tiny and ByteTrack tracking for tape conveyor speed measurement methodAbstract:
To address the problems of deformation of object motion, trajectory drift, and tracking loss leading to large errors in belt conveyor speed measurement, this paper proposes a fusion improvement of YOLOv7 tiny and ByteTrack tracking for tape conveyor speed measurement method. First, the improved YOLOv7-tiny object detection algorithm is used as a detector to achieve accurate positioning of objects in images. Second, a secondary data association strategy is used to strengthen the association matching of low-score confidence, while a Kalman filter with introduced confidence is used to predict the trajectory tends to the detector results, and improves the stability of object tracking trajectory. Finally, the camera calibration method is simplified by the image coordinates between the belt conveyor's two support rods and the distance between the support rods, and the belt conveyor speed measurement model is established to realize the speed estimation of the belt conveyor. The experimental results show that the MAE and MSE indicators of the proposed method have been reduced by 0.037 m/s and 0.022 m/s, respectively, effectively reducing the speed measurement error of the tape conveyor.
- 1
Study on the Influence of Drainage Channels on the Reinforcement Effect of Vacuum Preloading in Bauxite MudAbstract:
The self-consolidation process of tailings slurry stored in tailings ponds is exceptionally slow, remaining in a slurry state for decades. To accelerate the consolidation of tailings slurry, the influence mechanism of vacuum preloading was investigated. Consolidation tests and vane shear tests were conducted to assess the consolidation effectiveness of vacuum preloading. Nuclear magnetic resonance (NMR) tests were also employed to reveal the evolution of microscopic properties during the vacuum preloading process. Experimental results indicated that the moisture content of the mine mud decreased from a maximum of 180% to 47.88%, with a 55% reduction in volume and an increase in shear strength to 26.8 kPa. The consolidation effect using sand drains was superior to that using drainage boards, primarily due to the sand drains' ability to consistently maintain vacuum pressure transmission during the reinforcement of mine mud. However, the distribution of internal pore water after consolidation exhibited similar patterns regardless of the drainage method used. The research findings provide a theoretical reference for accelerating the consolidation and settlement of tailings slurry.
- 1
Statistical Analysis of Potential Hazards in Non-coal Mines in Sichuan Province and Suggestions for Safety ManagementAbstract:
In order to study the hidden danger characteristics of non-coal mine mountain in Sichuan province, reinforce the safety management of non-coal mine mountain continuously, the number, type and major hidden dangers of 188 mines in 4 categories, including underground mines, open-pit mines, tailings ponds and waste dumps, are statistically analyzed, and the proportion of general hidden dangers and major hidden dangers are respectively 91.20% and 8.80%. The major hidden danger accounted for the largest proportion of underground mines, accounting for 48.97%; The major hidden danger of field management is about 1.3 times than that of basic management. The types of major hidden dangers are mainly manifested in five aspects: drawing management, organization construction, slope management, mechanical and electrical transportation and flood drainage system. It is proposed that mining enterprises should increase safety capital investment, strengthen data management, and also pay attention to the control of high-risk points on site, strengthen personnel allocation and other measures to promote safety production. At the same time, it is suggested that safety supervision departments should grasp the key points, innovate the supervision mode, and use science and technology and expert power to achieve scientific and efficient supervision.
- 1
Experimental Study On The Flotation Of Cassiterite Using A New Type Of Collector SN-FAbstract:
Tri-n-butyl phosphate (TBP) is the most widely used auxiliary collector in cassiterite flotation, but it is sensitive to the process conditions such as selected particle size, slurry PH value, and air charge, which leads to the problems of foam instability, low recovery and high collector dosage in the actual production of a concentrator plant in Yunnan. Through the experimental study of the new cassiterite flotation collector SN-F, it is proved that SN-F has better adaptability to cassiterite selection conditions, which can improve the foam stability and enhance the collector's collection ability. The application of SN-F in industrial experiments increased the recovery by 10.69%, the tin concentrate grade by 0.63%, and the cost of the agent decreased by 34.31%, which had a significant effect of reducing costs and increasing efficiency, providing a new way for the efficient utilization of cassiterite resources.
- 1
Study on the Instability Characteristics and Unsaturated Seepage Characteristics of Rock Slope with Multiple Weak InterlayersAbstract:
Soft interlayer is usually the main internal factor of rock slope instability, and rainfall is usually the main external factor of slope instability. Therefore, for rock slopes with soft interlayers, the instability mechanism and seepage characteristics are worth further study. Taking the limestone open-pit slope with multiple soft interlayers in Nanshan, Chibi, Hubei Province as the research object, the instability characteristics are deeply explored by numerical simulation, and the unsaturated seepage characteristics are deeply studied based on the unsaturated seepage theory. The safety factors of each potential slip surface under the influence of seepage field are calculated by the Morgenstern-price method. The results show that the soft interlayer plays a particularly key role in both the overall instability failure along the soft interlayer and the local instability failure of the step. Under the influence of rainfall, the safety factors of each potential slip surface of the slope are reduced, but the decrease range is large in the early rainfall period, and tends to be stable in the late rainfall period.
- 1
Study on mechanism of strength strengthening and deterioration of clay-rich sandstone under high temperatureAbstract:
In order to investigate the effects of heat treatment on the physical and mechanical properties as well as the strength change mechanism of rich clay sandstone, specimens of rich clay sandstone were subjected to heat treatments at temperatures of 25°C, 200°C, 400°C, 600°C, and 800°C. Subsequently, physical parameter measurement tests and uniaxial compression tests were conducted on the treated specimens. It was observed that with increasing heat treatment temperature, the mass of the sandstone specimens decreased continuously. The wave velocity and modulus of elasticity exhibited an initial increase followed by a decrease trend while porosity and peak strain showed a decreasing trend followed by an increasing trend. The strength of the sandstone specimens demonstrated strengthening characteristics from 25°C to 600°C, but deteriorated from 600°C to 800°C. Finally, insights into the variation mechanism in strength for rich clay sandstone were revealed through aspects such as particle thermal expansion, mineral dehydration, mineral phase transition, and thermal decomposition. These research findings enhance our understanding of the thermal properties of rich clay sandstone and offer valuable insights for reinforcing underground space engineering after fire incidents.
- 1
Study on the influence of surface subsidence in underground mining of a phosphate mine based on FLAC3DAbstract:
Aiming at the influence of surface subsidence induced by open stoping and subsequent filling mining on surface industrial site in a phosphate mine, a three-dimensional model of filling after top-down phased mining of ore body is established by FLAC3 D. Through numerical analysis, the deformation of overlying strata and surface subsidence in different mining stages is explored, and the distribution of surface displacement and subsidence in different mining stages is obtained. The comprehensive simulation results are analyzed. With the progress of stage mining, the filling area of goaf increases, and the surface subsidence value also increases gradually, showing the law that the settlement value in the early and middle stages is larger and the later stage is smaller. The maximum surface subsidence value is 72.94 mm. Combined with the analysis of the calculation results of the displacement, inclination value i and curvature k of the near-industrial site on the surface, it can be seen that the deformation movement value of the selected site meets the protection level requirements of grade I and grade II, and the selected point still retains a certain distance from the industrial site. Preliminary research shows that the safety impact of designed underground mining on the surface industrial site meets the requirements of the specification. This study provides a useful reference for the study of surface subsidence and ground pressure control during the mining process of similar large mines from top to bottom.
- 1
Research and Application of Positioning Technology for Mine Inspection Robot Based on UWB and IMU FusionAbstract:
Aiming the issues of environmental impact, low positioning accuracy, and poor real-time performance of underground inspection robots in mines. A fusion positioning method based on UWB and IMU is proposed. Firstly, the UWB ranging module is used to measure the distance between mobile robot and the UWB base station. Secondly, a GRU neural network model is constructed by incorporating UWB measurement distance and real distance into the neural network model for training, resulting in a GRU correction model. Then, the GRU neural network correction model is used to adjust the measured distance, suppress NLOS distance error in complex environments, and obtain a more accurate distance than before. Finally, the corrected distance information is combined with the data provided by IMU through ESKF to construct error state equations and measurement equations. The error state of the system is evolved and the state estimation is updated separately to complete the state update and calculate more accurate position coordinates. The experimental results showed that under three different NLOS environments, the corrected static experimental positioning error increased by 6.09%, 15.56%, and 18.89% respectively compared to before. And the average positioning error in the composite scene has increased by 11.36% compared to before. In the dynamic experiment, the corrected average positioning error increased by 11.1% compared to before. Therefore, by correcting the pseudorange measured under non line of sight, the impact of non line of sight is reduced and its positioning accuracy is improved.
- 1
Research on carbon emission accounting system for underground mine miningAbstract:
At present, the accounting of carbon emissions is still only at the theoretical level of carbon emissions, and there is a lack of unified management and analysis of carbon emissions in the process of mine production. In view of the current situation of carbon accounting in underground mining, the existing accounting methods were sorted out and summarized, and the method based on life cycle assessment and carbon emission coefficient method was adopted, and the carbon emission prediction and measurement model was constructed by combining the production management data and process equipment of the mine. Based on this, the MVC three-layer architecture was used to build an underground mine mining accounting system platform, and the functional decomposition and interface design were carried out according to the six main modules, including production data entry, prediction model calculation, and measured model calculation. Through the application of Chengchao mine, it is shown that in addition to high-power and high-energy-consuming process equipment such as lifting and ventilation, transportation, support and pneumatic drilling equipment are also key carbon emission points, and the error of the prediction model meets the accuracy requirements. The system can effectively realize the prediction and data analysis of carbon emissions from underground mining, and guide the carbon reduction decision-making of mines.
- 1
Optimization of control drainage scheme and prediction of pit inflow based on numerical simulation of groundwaterAbstract:
The prediction of the temporal and spatial changes in groundwater discharge and seepage field in an underground mining area is of great significance for the water control project in mining, which directly relates to the safe production and environmental protection of the mine. The Kamoya copper-cobalt mine is located in a nappe body within the "Zambia-Congo" mineral belt, with complex hydrogeological conditions. According to the traditional dewatering scheme, the estimated groundwater discharge is more than 46,000 m3/d. Through on-site hydrogeological survey, by utilizing the multi-layered structure of the aquifer and the principle of controlling dewatering, a targeted single-layer control dewatering scheme was proposed. Using groundwater flow theory and numerical modeling technology, a three-dimensional numerical model of the groundwater was established to accurately reflect the hydrogeological characteristics of the mining area, and the precise prediction of groundwater dynamic changes was achieved. By optimizing the dewatering borehole layout during underground development, the predicted groundwater discharge in Section 940 was reduced to 25260 m3/d. The mine was constructed according to the optimized control dewatering scheme, achieving pressure mining in the initial mining section, and saving approximately $2.34 million in drainage costs per year compared to the traditional dewatering scheme. The single-layer control dewatering method can provide reference for similar large water mines in Africa, thereby achieving the goal of reducing groundwater discharge, protecting mining area water resources, and efficient pressure mining.
- 1
Ecological Vulnerability Assessment and Restoration Strategy of Open-Pit Limestone MineAbstract:
Based on the ecological degradation and damage mechanism of the open-pit limestone mine in Jinan City, a pressure-state-response model (PSR) was selected as the theoretical framework to construct the ecological vulnerability assessment index system of the mine in Jinan City, including the ecological and environmental factors of the mine. The application analysis and verification were carried out in Lijiapo abandoned open-pit mine in Jinan City. At the same time, a set of preliminary evaluation system suitable for project acceptance and short-term evaluation of ecological restoration effect has been proposed. The intrinsic relationship between the preliminary evaluation system and artificial natural restoration model was discussed, and the ecological restoration measures adopted in the preliminary evaluation system were considered as the starting point of artificial natural restoration model. According to the vulnerability analysis and evaluation standard of Taishan region, EVI=3.75 is set as the limit value of the low level of ecological vulnerability of the mine, and it is considered that the vegetation coverage rate at this time could achieve an ideal natural restoration effect. The inverse method has been proposed to calculate the vegetation coverage rate, and the results obtained by the inverse method are highly consistent with the actual project. The inverse method can quantify the degree of artificial interference, which is the specific practice of guiding mine restoration concept in Taishan region, and finally the ecological restoration strategy of "ecological reshaping, regional regulation, landscape reconstruction" has been put forward.
- 1
Shear behavior analysis of rock mass structural plane based on discrete elementsAbstract:
The structural plane of rock masses plays a crucial role in geological engineering as it significantly affects rock mass stability and engineering safety. To investigate the mechanical behavior of these planes under various shear conditions, this study employs PFC 2D to analyze regular, asymmetric, and irregular structural planes with different roughness under varying normal stresses. The results classify shear failure modes into four types: sliding along the sawtooth surface, sliding with shearing at the sawtooth tip, failure extending from one sawtooth edge to another through the sawtooth slope bottom, and complete shear failure at the sawtooth bottom. As normal stress and relief angle increase, the failure mode transitions from sliding along the stress side to sliding along the entire sawtooth surface and ultimately leads to complete shear failure at the sawtooth base. The shear strength parameter increases linearly with normal stress and fluctuation angle. Meanwhile, the shear resistance of irregular structural planes rises linearly with shear displacement, and there is minimal correlation between normal stress and JRC value.
- 1
Early warning method for dynamic roof hazards in mines based on multi-point displacement data and dynamically weighted ARIMA predictionAbstract:
Monitoring and early warning of dynamic roof hazards in mines is crucial for mining production and personnel safety. Traditional multi-point displacement monitoring and early warning methods rely on a single absolute threshold based on monitoring data, resulting in poor sensitivity and reliability of the warnings. In response to this issue, we propose a new early warning method for dynamic roof hazards in mines based on multi-point displacement data and the Autoregressive Integrated Moving Average (ARIMA) model. This method employs superposition techniques to enhance the signal-to-noise ratio of multi-point displacement time series data. We introduce a joint enhanced windowed waveform characteristic function ratio and kurtosis-based graded early warning method, addressing the inadequacies of traditional threshold warnings. Furthermore, we construct a dynamic weighted parameter ARIMA model to predict displacement data, enabling the integration of monitoring and prediction data for early and advanced warning of dynamic roof hazards in mines. The theoretical testing of this method shows a false alarm rate of 13.3%, with an average error of 15.4% for secondary or higher warning characteristic values. Actual engineering data tests conducted over two periods resulted in false alarm rates of 12.5% and 7.1%, with average errors for secondary or higher warning characteristic values of 15.1% and 14.4%, respectively. In summary, the proposed method can serve as an important approach for early warning of dynamic disasters related to mine roof stability, with significant potential applications.
- 1
Applications and Development Trends of Intelligent Robots in Explosives HandlingAbstract:
With the gradual depletion of shallow resources, deep mining will become a norm. The "high stress, high borehole temperature, high karst water pressure" environment poses huge challenges to blasting construction, making deep well working conditions increasingly difficult. The appearance of intelligent robots provides a new perspective for deep well blasting operations. Analyzing the advantages and bottlenecks of intelligent robots in blasting construction can help advance the technology of intelligent robots. Based on this, the technical basis of robots is described, the advantages and difficulties of intelligent robots in blasting operations are analyzed, the application prospect of intelligent robots in blasting accident handling is analyzed, and the key research direction and development trend of intelligent robots in the future are proposed. That is, optimizing the structure or improving the compensation means, improving the accuracy of sensors, achieving self-adaptive control of parameters, and constructing a chain control system to provide an optimized approach for intelligent robots to operate efficiently and of high quality in blasting environments.
- 1
Experimental investigation on the concentration of bottom flow of full tailing sand release based on ultrasonic inflow effectAbstract:
In order to study the influence of ultrasonic frequency, power and application time on the underflow concentration of full-tail mortar, ultrasonic technology was introduced to explore the effect of ultrasonic coupled with mud layer on the underflow concentration and sand discharge of thickening machine.Firstly, the directivity of ultrasonic wave in all tailings slurry is analyzed by MATLAB, and the optimal frequency range of ultrasonic wave is selected.Then, the optimal frequency of ultrasonic wave is further determined by interpolation fitting method.Finally, the optimal frequency, power and application time of ultrasonic wave are calculated through the interaction of factors, and verified by SVR model.The results show that when the ultrasonic frequency is 28kHz, the propagation directivity in the thickener is better.Under suitable ultrasonic conditions, ultrasonic has a significant effect on increasing the final mass concentration of full-tail mortar.The optimal operating condition of the ultrasonic wave for flocculation settlement of the whole tailings is as follows: after the natural settlement of the whole tailings for 1min, the ultrasonic wave with the frequency of 28kHz and the power of 100W is the optimal operating condition.
- 1
Study on temperature field analysis and optimal layout of double circle freezing hole in loose and weak formationAbstract:
Taking aking the loose and weak strata in the freezing section of the main shaft of a mine in Laizhou as the research object, the temperature field distribution law of the double-ring freezing hole was compared and analyzed by means of field measurement and ANSYS numerical simulation. It was found that the freezing effect of the double-ring freezing hole was not ideal. Then a new three-ring freezing hole optimization scheme is proposed. The freezing effect of temperature field before and after optimization is analyzed and compared by arranging single-ring freezing hole on the inner wall of wellbore and double-ring freezing hole on the outer wall with ANSYS finite element software. The results show that the optimized scheme shortens the circulation time by more than 10d, effectively reduces the internal temperature of the wellbore and speeds up the circulation time of the frozen wall. After freezing for 60 days, the thickness of the frozen wall of the optimized scheme has reached about 4.8m, which is much larger than that of the original scheme, and the temperature is about 4~5℃ lower than that of the original scheme. This shows that adding a circle of freezing holes in the shaft is an effective method, which can quickly reduce the temperature around the shaft to the lowest, and play a certain guiding role for shaft excavation with complicated geological conditions such as safe construction of shaft excavation and difficult freezing.
- 1
Research on Strength of Tailings-Waste Rock Composite Cemented Filling Material Based on Orthogonal TestAbstract:
To address the serious accumulation of solid waste and the low overall strength of the filling body in a certain mine, tailings and waste rocks were used as filling aggregates, with polypropylene fibers added as admixtures. The orthogonal experimental method was adopted to explore the influence patterns of cement-sand ratio, waste rock grading, and fiber content on the slump of filling materials and the strength of the filling body, and to determine the optimal filling scheme. The results show that the primary and secondary factors affecting the slump of filling slurry are waste rock grading, fiber content, and ash-sand ratio, while the factors affecting the 28-day compressive and tensile strength are ash-sand ratio, fiber content, and waste rock grading in order. Both the reduction of ash-sand ratio and the increase of waste rock grading index n weaken the strength of the filling body. The maximum strength of the filling body is achieved when the fiber content is increased to 0.6%, and then it decreases. Based on the coupling effects of major factors, a fitting function for strength and slump was established, and a three-dimensional model diagram of the relationship between major factors and various index values was established, both of which conformed to the relationship of Z=Ax^2+By^2+Cx+Dy+Exy+F. Based on orthogonal experiments and actual mine requirements, the optimal parameters were obtained: ash-sand ratio of 1:5, waste rock grading index of 0.8, and fiber content of 0.6%. Under these conditions, both the fluidity of the filling slurry and the strength of the filling body could meet the filling requirements of the mine.
- 1
Application research of double-row micro-piles and frame structure to reinforce cracking and deformation of belt corridor foundationAbstract:
In order to solve the problem of foundation cracking and deformation of the ore transportation conveyor belt system, i.e., S2-S3 sections, which are located in the southern open-pit of the MS Mine of Serbia Zijin Copper Doo, a comprehensive method of field investigation, theoretical analysis, micro-pile reinforcement, and effect verification was adopted. First, the current status of cracking and the surrounding environment were surveyed through field investigation, and the change rules of the monitoring radar data, which monitored the surrounding slope conditions, were analyzed; secondly, the mechanism of cracking and deformation of the S2-S3 section was analyzed through the characteristics of stratum lithology and terrain conditions; then, a double-row micro-pile and frame structure reinforcement scheme was designed and implemented; finally, the effect of the reinforcement scheme was evaluated through on-site comparison before and after the execution of the reinforcement project within the transportation conveyor belt system foundation according to the analysis of the monitoring radar data of its outer slope. The results show that after the implementation of the reinforcement scheme of double-row micro-pile and frame structure, the reinforcement effect was good, the cracking and deformation trend was suppressed, the integrity and bearing capacity of the foundation were improved, and the expansion and conduction of cracks were effectively controlled. The research results can provide useful reference for similar geotechnical engineering projects that urgently need reinforcement and treatment.
- 1
Study on transport performance of coarse aggregate paste filling slurry and strength optimization of filling bodyAbstract:
The transport performance and strength of paste filling slurry are important contents of filling technology. In order to explore the transport performance of paste filling slurry with coarse aggregate and the evolution law of backfill strength in a mine, the response surface analysis research method was used to carry out the fluidity test and strength ratio experiment of backfill material. Based on the response surface test results, the effects of single factor and multi-factor interaction such as coarse aggregate content, lime sand ratio and mass concentration on the conveying performance of the filling slurry and the strength of the backfill were analyzed. The results show as follows: 1) Under the influence of a single factor, the sensitivity factors of backfill strength from large to small are the ratio of lime to sand, mass concentration and proportion of coarse aggregate; for the collapse of filling slurry, the sensitivity factors from large to small are the proportion of coarse aggregate, mass concentration and proportion of lime to sand;2) Based on the response surface method, the response regression model of the collapse degree and strength ratio of the filling slurry is established. The predicted value of the model has a good linear relationship with the test value, and the model has a high degree of fit and reliability.3) For backfill strength, the interaction between concentration and lime sand ratio has the most significant influence on backfill strength; For the collapse of filling slurry, the interaction of coarse aggregate ratio and concentration ratio has the most significant effect on the collapse of filling slurry.4) The parameters of backfill strength and filling slurry collapse were optimized, and the optimized parameters were as follows: coarse aggregate content 30.7%, lime sand ratio 1:6, and concentration 82%. The errors of the test values and predicted values of backfill strength and slurry collapse were all within 5%, which can verify the reliability of response surface analysis method in optimizing backfill strength and filling slurry collapse.
- 1
Study on the size effect of damage and failure of gangue cemented filling cylinderlAbstract:
There are significant differences in mechanical properties and failure modes among filling materials of different sizes. In order to study the size effect of the backfill body, the scanning electron microscope experiment was carried out on the cylindrical specimens of different sizes of gangue cemented filling body, and the microscopic morphology difference of different sizes of specimens was observed. Conduct uniaxial compression experiments on specimens with different sizes of filling body, and using an acoustic emission meter to monitor the energy release during the loading process, numerical simulation technology is used to simulate and verify the compression failure of the specimen and study the size effect and damage characteristics of cylindrical filled specimens of different sizes. The results show that the larger the specimen size, the more weak points in the specimen, and the worse the cementation ability of the specimen. The uniaxial compressive strength of the specimen is inversely proportional to its size, and the small size specimens mainly exhibit shear failure. When the specimen size increases to a certain extent, it exhibits a certain degree of tensile failure. The specimen exhibits more significant size effects as the specimen size increases, and the acoustic emission activity of cylindrical specimens shows three stages: stable, increasing, and decreasing. The acoustic emission activity of the small size specimen is more intense than that of the large size specimen. By studying the size effect of gangue cemented filling cylinder specimen, it can provide scientific basis for the filling body parameters of different size structures in filling.
- 1
Study on mining scheme and optimization of structural parameters of residual pillar under the condition of filling body coveringCHENG Bin1, YANG Ning2,3, WU Huiming1, FU Zhouyun2,3, PENG Yuejin2,3Abstract:
Due to the unreasonable use of pre-mining methods and historical reasons such as civil mining and illegal mining, there are many residual pillars and top pillars under the condition of filling body wrapping in a high-grade iron mine. In order to recover high-grade iron ore resources as much as possible and avoid waste of resources, the recovery scheme of residual pillar and top pillar is studied. Through the comparative analysis of the technical and economic indexes of the downward drift filling mining method and the sublevel filling mining method, the sublevel filling mining method with simple mining process, high mining intensity and low production cost is selected as the best mining method for residual pillar recovery, which can create about 63.05 million yuan of economic benefits for the mine. According to the selected mining method, the structural parameters of 606 # pillar and-525 m sublevel top pillar mining are optimized by numerical simulation. The displacement, stress and plastic zone indexes of surrounding rock and filling body under different structural parameters are analyzed. When the length of the room is 30 m and there is no top pillar, the maximum displacement of the roof is 50.00 mm, and the area of the top plastic zone is the smallest, which is 1534.55 m3, which is the best mining scheme for 606 # pillar. When the span of the room is 8m × 10m and the length is 25m, the maximum displacement of the roof is 55.65mm, and the volume of the plastic zone per unit area of the roof is the smallest, which is 0.93m3.There is no obvious penetration in the plastic zone of the filling body in the stope, which is the best top pillar mining scheme.
- 1
Study on rock block size and energy dissipation of secondary crushing in Pulang Copper MineAbstract:
During the mining process at the Prang Copper Mine, which was conducted using the natural avalanche method, a large number of large boulders with dimensions exceeding 1.2 metres were generated. These large pieces of ore rock in the handling and transportation are easy to lead to equipment clogging, increase the cost, need to carry out secondary crushing. In order to effectively solve this problem under the existing blasting conditions, with the help of finite element numerical simulation technology, we analyzed in detail the secondary crushing block size and energy distribution characteristics of different sizes of large blocks under different gun hole arrangements. Firstly, the rock mass distribution was obtained through image processing and on-site measurement, and the mineral rock was categorized. Secondly, finite element software was used to simulate the blast stress evolution, crack expansion and energy dissipation. The results of the study show that different gun-hole arrangements have a significant effect on the crushing effect of massive mineral rock. When the number of holes increases, the internal stress distribution of the rock is more uniform, and the crushing effect is enhanced. When the number of holes is the same, the three typical rock masses are subjected to close blast load pressure at the same distance from the holes. Explosive loading pressures decay rapidly with increasing distance from the borehole. In multi-hole blasting, the stress value on the center line of two-hole distribution is the largest. The stress value on the center line of the three-hole distribution is the smallest. The number of holes increases, the number of cracks increases and longer cracks or more extensive crack networks are formed in the block and directional crack zones are formed by multi-hole blasting. The block size after multi-hole blasting is characterized by uniformity and fragmentation, while single-hole blasting tends to produce large blocks. The number of holes has an increasing relationship with the maximum values of kinetic and internal energy, and the ratio of internal energy to kinetic energy of rock increases with the number of holes and decreases with the increase of chunk size. Therefore, in the construction of secondary crushing of copper ore rock in Prang, for the smaller size of the bulk rock, it is recommended to use single-hole blasting; for medium and large-sized bulk rock, it is recommended to use double-hole blasting.
- 1
LiDAR-Based Algorithm and Research for Roof Deformation Monitoring in Mine Working FacesAbstract:
Addressing the precise monitoring requirement of roof deformation in mine working faces, we have designed a LiDAR-based monitoring system, developed a complementary deformation monitoring algorithm, constructed a comprehensive system architecture, and conducted deformation risk assessments specifically tailored for the complex environment of mine working faces. The system employs time-lapse scanning to acquire two-phase point cloud data of the mine working face. Following preprocessing steps such as angular transformation and ICP registration, the system utilizes high-precision triaxial tilt sensors to real-time calibrate the LiDAR's attitude, enabling precise extraction of the roof's point cloud morphology.Subsequently, the Delaunay triangulation method is applied to process the two-phase point clouds, and innovatively incorporates a point-to-plane monitoring algorithm to calculate the distance between the central points of the second phase and the triangular facets of the first phase, thereby enhancing deformation monitoring accuracy and facilitating rapid and precise quantification of deformation data.Furthermore, leveraging the DBSCAN clustering algorithm, we propose a deformation point cloud density clustering filtering algorithm that identifies and labels deformation areas. Based on this, a risk level assessment is conducted, realizing intelligent monitoring of roof deformation. Field research results demonstrate that this monitoring system and algorithm achieve a monitoring accuracy ranging from 1mm to 5mm, significantly outperforming traditional monitoring methods in terms of precision.Moreover, the system enables the visual representation of deformation areas, providing robust technical support for mine safety production and further enhancing the safety and reliability of mining operations.
- 1
Study on the mining deformation behavior and law of many middle section of XitieshanAbstract:
In response to the problem of dynamic disasters induced by multi section joint mining in deep mines, the stress evolution law and surrounding rock deformation behavior characteristics of the multi section mining area were studied. Through geological investigation, theoretical analysis, numerical simulation, and data processing methods, the stability of the multi section mining area of the eastern 03-011 line of the 2402-2522 Xitie Mountain lead-zinc mine was studied. The deformation and failure behavior of the surrounding rock and ore body during the mining process were demonstrated, and the following conclusions were drawn: the deformation and failure of the multi section mining area in Xitie Mountain mainly occurred in individual thick and large mining areas and in the middle of the mining area. The maximum settlement of the top pillar position in the middle section of the current mining situation is close to 4cm, and there is currently no significant risk. The displacement of 14003-3 in the 2462 middle section of the subsequent mining is the largest, with a settlement value exceeding 6cm. Multiple mining sites on both sides have a displacement of about 5cm, and there may be partial collapse of some mining sites. Based on the spatiotemporal evolution characteristics of deformation and failure in multi-stage mining, measures were planned for potential ground pressure problems during the mining process, providing theoretical support for safe and efficient mining in multi-stage mining areas in the future.
- 1
Research on stope stability of reserved retaining wall upward horizontal filling mining methodAbstract:
Reasonable mining methods and structural parameters are crucial for ensuring the safety and efficient production of mines. According to the characteristics of large thickness variation of a copper ore body, the mining scheme of the ore body is optimized by combining the analysis of rock joint and fracture, the evaluation of rock integrity, the allowable exposed area of the ore body and the self-stability ability of the rock body. Through FLAC3D numerical simulation, the stress, displacement, and failure patterns within the stope of the upward horizontal filling mining method with wall support have been analyzed. The research results indicate that the maximum tensile stress during the recovery process never exceeds the ultimate tensile strength of the ore body. As the mining progresses, the maximum compressive stress migrates from the lower left tip of the goaf to the roof near the upper right tip, and as the stratification increases, the compressive stress at the tip gradually decreases. Under the condition of a determined exposure area, the smaller the short-span width, the greater the amount of subsidence of the roof. The mining process leads to an intensification of bottom stress and deformation, and the phenomenon of floor heave at the bottom of the fill body and the surrounding rock is significant. The shear failure is mainly concentrated at the tip of the stope and extends into the deep surrounding rock. The results show that due to the existence of the hanging wall, the expansion of the surrounding rock failure zone to the empty area is effectively separated, and the stability of the stope is improved.
- 1
Research on multi-middle section collaborative mining technology of an underground crushing mineAbstract:
Because the mining method can not meet the increasing production demand, it wants to transform into a filling and co-mining mode of multi-section and multi-point operation, and proposes to study the mining method of filling the crushed ore body to ensure that the mine can reach production smoothly. Combined with the technical conditions of on-site mining, the sectional rock drilling stage empty field and then filling mining method of constructing the top pillar of the lower middle section in advance at the bottom pillar position of the middle section were innovatively proposed, and different mining areas were divided according to the characteristics of the ore body in the typical middle section of 414, and different mining schemes, sequences, stope structure parameters and backfill strength were designed for each mining area, which effectively solved the problem of multi-middle section and multi-point collaborative mining of the broken ore body from various aspects and multiple angles. The application results show that the optimized 414 ore body meets the original production demand of 500t/d of the mine, and the dilution rate and loss rate are reduced compared with the original mining method, and the operation safety of underground workers is also guaranteed accordingly, and there is no roof collapse.
- 1
The impact mechanism of ecological restoration projects in large-scale antimony mining areas on the migration and release of antimony in groundwaterAbstract:
The ecological restoration project of Xikuangshan in Hunan has solved the problem of antimony pollution in the abandoned mine land. However, there are fewer studies on the impact of ecological restoration project on the evolution of antimony content in groundwater. Groundwater samples collected from the antimony mining area in 2016 and 2023 are used to analyze the changing patterns in hydrochemistry and antimony content before and after ecological restoration by applying the hydrochemical analysis and hydrogeochemical modeling. The results show that (1) Antimony contamination in three limestone aquifers in the mining area is affected to varying degrees by the ecological restoration. The Shetianqiao Formation and Xikuangshan Formation are more significantly impacted by mining activities and human activities, resulting in a general increase in antimony concentration in the aquifers. In contrast, the Lower Carbonifer aquifer shows a more pronounced response to the ecological restoration project due to its deeper groundwater levels and the presence of impermeable layers, indicating that a decrease in antimony content. (2) The source of Sb before and after ecological restoration shows strong heterogeneity, and the large-scale soil covering and greening project significantly affects the migration and transformation of Sb. (3) The ecological restoration project has changed the redox environment, accelerating the oxidation of Sb (III) to Sb (V) in the groundwater. This study will provide a scientific basis for the prevention and control of heavy metal pollution in future ecological restoration projects in mining areas.
- 1
Study on Application of a New Mud Inhibitor in Flotation of Copper and Molybdenum MineAbstract:
A copper molybdenum ore in Pakistan mainly contains copper, molybdenum, gold, silver four valuable elements, the content of 0.55%, 0.01%, 0.1g/t, 1.15g/t. The high content of easy mud gangue minerals such as sericite and chlorite in the ore results in low grade of copper concentrate. Study of the beneficiation test of the mine was carried out,in order to solve the problem. A new inhibitor, CD-B, was used to inhibit argilized gangue minerals. After three roughing and regrinding and reconcentrating of coarse concentrate, copper-molybdenum mixed concentrate containing Cu 26.76% and Mo 0.451% can be obtained, with Cu recovery of 94.49% and Mo recovery of 77.48%. It contained 2.06g/t Au and 32.66g/t Ag, and the recoveries of Au and Ag were 40.17% and 55.38% respectively. The new agent is a small molecule organic matter, zero toxicity, low drug consumption, and belongs to efficient green environmental protection agents.
- 1
Research on grinding performance of vertical spiral stirred mill based on DEM-CFD couplingAbstract:
The vertical spiral stirring mill has gradually replaced traditional ball mills in fine grinding, regrinding, and ultrafine grinding operations due to its advantages in efficiency, energy saving, and compact footprint, and has been introduced into the mineral processing industry. To analyze the impact of structural parameters on the grinding performance of the vertical spiral stirring mill, this study employs a coupled approach of Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD). Firstly, a numerical model of the vertical spiral stirring mill is constructed to analyze the changes in the dynamic characteristics of the grinding media during the grinding process. Secondly, grinding experiments are conducted based on a test rig, using the torque driven by the spiral stirrer as an indicator to validate the accuracy of the simulation model. Subsequently, the effects of structural parameters (mill bottom clearance, side clearance, and stirrer spiral lift angle) on grinding performance are simulated and analyzed, and a comprehensive evaluation method for grinding performance is proposed. Finally, through multivariate analysis, the influence degree of each parameter on grinding performance is examined.The study indicates that the mill bottom clearance, side clearance, and stirrer spiral lift angle significantly affect grinding performance, with the sensitivity ranking of the variables being side clearance, bottom clearance, and stirrer spiral lift angle. This research provides a basis and reference for the optimization design of the vertical spiral stirring mill.
- 1
Study on rheological parameters and transport characteristics of unclassified tailings slurry backfill in Daye Iron MineAbstract:
Pipeline transportation is a crucial component of mine filling systems, and the rheological parameters of the filling slurry are essential for pipeline transport design. This study focuses on the filling slurry made from unclassified tailings of the Daye iron mine. Rheological parameters were investigated through rheological tests, and these parameters were then used in Fluent software for numerical simulation to study the transport characteristics in pipelines. The experimental results indicated that when the slurry mass concentration is between 60% and 70%, the fitted relationship curve between shear stress and shear rate conforms to the Herschel-Bulkley (H-B) model. As the slurry concentration increases, this relationship transitions from the H-B model to the Bingham model. The Daye filling slurry is a shear-thickening fluid, with yield stress and viscosity coefficients showing an exponential relationship with slurry concentration. Numerical simulation results show that when the slurry mass concentration exceeds 65%, the static pressure at the pipeline outlet begins to exhibit a symmetrical distribution, and the slurry flow state becomes relatively stable. Pipeline resistance loss is positively correlated with both slurry concentration and flow rate. When the slurry concentration reaches 68%, the resistance loss starts to increase significantly. These findings provide theoretical support and guidance for designing pipeline transportation parameters in mine filling systems.
- 1
Effects of Acidic Environment and Fly Ash Dosages on the Early Strength Formation of Sulphoaluminate-based Grouting MaterialsAbstract:
In order to study the strength formation mechanism of sulphoaluminate-based grouting materials with different dosages of fly ash under acidic conditions, the early strength development and microstructure evolution of sulphoaluminate-based grouting materials were characterized by unconfined compressive compression, XRD phase analysis, TG thermal analysis and MIP mercury intrusion tests. The results show that less content of fly ash content in grouting materials leads to the less loss values of compressive strength affected by acidic environment, which is because the aluminum adhesive is corroded and stripped by H+ to reduce the crystallization pressure, and the acidic environment hinders the dissolution of active Al in high-calcium fly ash to reduce ettringite formation. In addition, the increase of fly ash addition and acidic environment increase the threshold pore size and porosity (pore volume of mesopores and macropores) of solidified grouting materials, resulting in the decrease of the early hydration strength of grouting materials. In actual grouting reinforcement, the negative effects of acidic environment and external additives on the setting rate of cementitious system and the early strength of solidified grouting materials should be fully considered to ensure the grouting reinforcement effect of coal roadway.
- 1
Application of a Novel Pyrite Depressant in Separating Chalcopyrite-PyriteAbstract:
In the process of chalcopyrite-pyrite separation flotation, lime is usually used as a pyrite depressant. Although it’s cheap, the usage of a lot of lime will cause a series of problems such as pipeline blockage and environmental pollution. Therefore, in order to partially or completely replace lime, a new pyrite depressant PN was developed and applied to the separation of chalcopyrite-pyrite. The flotation performances and adsorption mechanism were systematically studied by micro-flotation test, contact angle measurements, UV spectrum, FT-IR, XPS and SEM-EDS. The conclusion could be drawn as follows: The results of flotation test show that the depressant has little effect on the recovery rate of chalcopyrite, but has great selective effect on pyrite. A satisfactory separation effect, a copper concentrate with 31.3% Cu and a recovery of 92.9% was obtained in artificial mixed minerals tests. The optimum separation performance was realized under conditions of 5 mg/L PN、30 mg/L SBX and 10 mg/L MIBC, when pH was 8. The results of contact angle analysis show that the hydrophilicity of pyrite surface is improved after adsorption of PN. SEM and FT-IR confirmed the adsorption of inhibitors on pyrite surface. In general, PN has a better depressing effect on pyrite than lime and can replace lime in the separation of chalcopyrite-pyrite.
- 1
Monitoring of infiltration depth and stability analysis of ion-type rare earth mine slope under different rainfall conditionsAbstract:
Rainfall is a primary factor inducing landslides on slopes, especially on repaired slopes of ion-adsorption rare earth mines after in situ leaching. This study analyzes the infiltration characteristics and stability of these slopes under various rainfall conditions. Using soil moisture monitoring data and finite element simulation techniques, the effects of rainfall amount, duration, and type on slope stability were examined. The study categorizes effective rainfall types into single-peak, concentrated, multi-peak, and uniform based on their temporal distribution. In concentrated and uniform rainfall events, the instances of infiltration depths exceeding 10 cm and 60 cm were 15.63% and 1.04%, and 17.71% and 5.21%, respectively. In single-peak and multi-peak rainfall events, the instances of infiltration depths exceeding 10 cm and 60 cm were 37.50% and 8.33%, and 29.17% and 11.46%, respectively. With increasing rainfall duration, the stability coefficients of slopes under concentrated and uniform rainfall conditions initially decrease slowly and then rapidly. Conversely, under single-peak and multi-peak rainfall conditions, the stability coefficients initially decrease rapidly and then slowly. This study provides a theoretical basis for analyzing the infiltration characteristics of ion-adsorption rare earth mine slopes under various rainfall conditions and for preventing rainfall-induced landslides.
- 1
Study on roof stability and support parameter optimization of stope with high stage crushing and fillingAbstract:
In underground metal mining, the stability of stope roof is directly related to the overall safety of high stage filling stope. In this paper, we take the two types of different height quarries in Zhongguan Iron Mine as the engineering background, and use the combination of on-site testing and numerical simulation to determine the appropriate anchor length by testing the range of loosening circle of the pre-control top lane without the influence of mining, and compare and analyze the deformation of the quarry roof by simulating the different anchor support schemes to determine the parameters of the anchor arrangement. The results show that: (1) the loose circle range of the gang part of -170 m level and -200 m level pre-control top lane is about 1.4-2.3 m and 1.6-2.0 m, and the length of anchor rods is determined to be 2.4 m. (2) the deformation of the overlying rock layer continues to decrease with the decrease of the spacing of the anchor ropes. the average values of the percentage increase of the control effect in the 30 m quarry are 37.15 %, 37.50 %, and 26.25 %, and that in the 60 m quarry the average value of the percentage increase of the control effect is 37.15 %, 37.50 %, and 26.25 %, respectively, 26.25 %, and the average values of percentage increase of control effect for 60 m quarry can be obtained as 36.65 %, 34.00 % and 30.35 %. Considering the economic cost and construction intensity, the spacing of anchor cables in the pre-controlled top lane of 30 m and 60 m height of the quarry was determined to be 2.5 m and 4.0 m, respectively.
- 1
Study on the Effects of Graphene Oxide on the Performance of Calcium Aluminate Cement-Based Grouting MaterialsAbstract:
This study investigates the changes in the early mechanical properties and later durability of sulfate-aluminate cement-based grouting materials with the incorporation of graphene oxide (GO). Macroscopic performance tests reveal that as the GO content increases, the fluidity of the grout decreases gradually. The addition of GO significantly enhances the mechanical properties of the sulfate-aluminate cement-based grouting materials. Experimental results indicate that when the GO content is 0.01%, 0.03%, 0.05%, and 0.07%, the 7-day compressive strength increases by 4.7%, 14.1%, 13.3%, and 11.7%, respectively. Notably, a GO content of 0.03% yields the most significant improvement in mechanical strength, suggesting that GO notably accelerates the hydration reaction of sulfate-aluminate cement-based grouting materials, with 0.03% being the optimal dosage. Microstructural analysis via XRD and SEM shows that GO promotes the hydration reaction without forming new hydration products. The bridging and blocking effects of GO within the microstructure enhance the stability of the sulfate-aluminate cement-based grouting materials, resulting in improved durability in underground environments. The findings suggest that GO not only enhances the early strength of sulfate-aluminate cement-based materials but also improves their long-term performance, offering theoretical insights and practical guidance for enhancing the durability of these materials.
- 1
Reasonable Strength of Stope Filling Body of Large Diameter Deep Hole Open Stoping Subsequent Filling MethodAbstract:
The rationality of the design of stope backfill bodies is crucial for the safety and efficiency of mining operations. Using the stage-by-stage large-diameter deep hole mining method with subsequent backfilling employed in a shallowly buried spodumene deposit as the background, this study investigates the reasonable strength of stope backfill bodies through theoretical calculations and FLAC3D numerical simulations. It explores the stress, displacement within the stope backfill body, and the surface subsidence deformation patterns.The research results reveal the following: The principal stress within the backfill body gradually increases with mining progress, and the stress is primarily compressive, with more pronounced effects at the upper and lower parts. Changes in the strength of the backfill body have minimal impact on the peak value of the principal stress; however, increased strength reduces the stress radiation range. As the strength of the backfill body increases, the suppression of subsidence of the stope roof intensifies, reducing the subsidence space and limiting roof deformation, with better constraint effects compared to the surface. Displacement within the backfill body is affected by excavation disturbances and shows a stepwise variation. When the strength is 2.5 MPa at the top and bottom and 1.5 MPa in the middle of the stope backfill body, the maximum tilt deformation, curvature, and horizontal deformation of the surface monitoring lines all meet the safety regulations for surface subsidence impacts on structures.
- 1
Experimental Study on the Mineral Processing of a Maghemite Iron Ore in ZimbabweAbstract:
The TFe grade of an iron ore located in Zimbabwe is 42.01%. In response to the challenges posed by the fine particle distribution and high silicate mineral content of this magnetite-red iron ore, a testing study was conducted using a combined process of magnetic separation followed by flotation to maximize the recovery of iron resources. The experiments investigated the effects of grinding fineness, regrinding fineness, magnetic field strength, as well as the slurry pH, corn starch dosage, lime dosage, and collector dosage on the flotation behavior of the weak magnetic tailings.Under the conditions of a grinding fineness of -0.037 mm at 81%, regrinding to -0.037 mm at 90% during the weak magnetic operation, and regrinding to -0.037 mm at 85% during the strong magnetic operation, a total of four weak magnetic selections and one strong magnetic selection were conducted. This yielded weak magnetic concentrate with an Fe grade of 62.26% and a recovery rate of 12.25%, while the strong magnetic concentrate achieved an Fe grade of 51.32% with a recovery rate of 64.76%.Further experiments were conducted on the strong magnetic concentrate using a self-developed collector CK-T1 in a reverse flotation test. Under the conditions of a slurry pH of 11, starch dosage of 500 g/t, lime dosage of 800 g/t, and CK-T1 dosage of 300 g/t, a closed circuit flotation process involving one roughing and two cleaning cycles along with two scavenging stages was performed, resulting in an iron concentrate with an Fe grade of 65.95% and a recovery rate of 81.45%.The product indicators demonstrate that effective recovery of this magnetite-red iron ore can be achieved. The findings provide a viable technological pathway for the development of this mineral, while also offering valuable references for similar ore types.
- 1
Safety Helmet Detection Method Based on Multi-Dimensional Expansion Lightweight YOLOv9Abstract:
Under the mine, the environment is more complex, and the monitoring equipment is susceptible to the interference of noise, light, and dust, which leads to the problems of low accuracy, leakage, and misdetection of YOLOv9 algorithm in detecting the wearing of helmets by the personnel under the mine. Aiming at this problem, a multi-dimensional expansion lightweight model MD-YOLO based on YOLOv9 algorithm is proposed, which aims to improve the accuracy and real-time performance of helmet detection. The MD-YOLO model firstly introduces the MEMCSPELAN module to replace the original RepNCSPELAN4 module, so that the model obtains a larger sensory field when detecting the helmet, and enhances the ability of capturing the global features, thus locating the target more accurately. ability to localize the target more accurately while reducing the computational cost. Second, the improved PD-Dyhead detector head is used to replace the detector head in YOLOv9, which enhances the model's ability to learn multi-scale features, and improves the computational efficiency while further enhancing the discriminative ability for small targets and targets that can be easily misdetected. Finally, the EMA-SlideLoss function is used as the loss function of the model category classification to improve the deficiency of the YOLOv9 model in dealing with the sample imbalance problem and to improve the robustness of the algorithm. The experimental results show that compared with the YOLOv9 algorithm, the MD-YOLO model achieves an average detection accuracy of 92.5%, which is 2.8% higher than that of the YOLOv9 model, the number of parameters is reduced by 26.6%, and the detection speed is improved by 27%. The MD-YOLO model is better than the comparison algorithm in terms of accuracy and real-time performance, and meets the needs of helmet wearing detection for underground workers.
- 1
Research on Support Load Classification and Prediction Based on WOA-DBNAbstract:
In coal mine production, roof collapse accidents in the working face are directly related to the hydraulic supports. Based on this theory, a prediction model based on multi-source data fusion is proposed for predicting the load of hydraulic supports. By studying the deformation characteristics of coal seam roof pressure, the composition and working principles of hydraulic supports, the bearing theory, and the impact of working face conditions on hydraulic supports, we analyze the factors influencing load variations and collect data on key stress components. We utilize the K-means clustering algorithm to perform cluster analysis on the data features and build a classification prediction model for the load. The Whale Optimization Algorithm (WOA) is employed to optimize the Long Short-Term Memory (LSTM) network and the Deep Belief Network (DBN), establishing WOA-LSTM and WOA-DBN serial prediction models. The results show that in the load prediction for the front column of the 20# hydraulic support, the WOA-DBN model reduces the Mean Absolute Error (MAE) by 0.2287, 0.2064, and 0.0677, and the Root Mean Squared Error (RMSE) by 0.2129, 0.1953, and 0.0725, respectively. In the load prediction for the rear column of the 20# hydraulic support, the MAE decreases by 0.3031, 0.2446, and 0.2054, and the RMSE decreases by 0.2919, 0.2464, and 0.2389, respectively. Therefore, the WOA-DBN serial prediction model is more suitable for load prediction and offers higher accuracy.
- 1
On the tensile properties and fracture characteristics of NSCB brittle specimens based on DIC testing methodAbstract:
In order to understand the effect of pre-existing fissure length on the tensile ability and crack deformation characteristics of different rock materials, the notched semi-circular bending specimens (NSCB) of three typical brittle rocks, granite, medium sandstone and limestone, were selected for the loading experiments. The results show that the fracture toughness of rock samples is positively correlated with basic mechanical parameters such as compressive strength, tensile strength and elastic modulus. The bearing capacity of NSCB samples is negatively correlated with the pre-existing fissure length. When the fissure length exceeds a certain value (a≥3mm), the bearing capacity of the NSCB specimen is approximately negatively exponential with the crack length. The deformation characteristics of NSCB samples are significantly affected by the rock crystal structure and micro crack distribution. The higher the cementation degree of rock minerals and the denser the rock crystal structure, the higher the fracture initiation stress, and vice versa.
- 1
Research on Optimizing Rockburst Disaster Prediction Model by Integrating Bayesian Parameter Optimization and Multi-Head Attention MechanismAbstract:
In order to address the issues of uneven sample data and low prediction accuracy encountered in constructing a rockburst intensity grade prediction model, we integrated the Bayes parameter optimization algorithm (BO) and multi-head Attention mechanism under a strategy of equalizing rockburst sample data. We propose a rockburst intensity grade prediction model (BO-CNN-LSTM-Multihead-Attention) based on convolutional neural network (CNN) and long short-term memory network (LSTM). The predictive indexes selected for 224 groups of rock burst cases at home and abroad include the elastic deformation energy index W_et, rock stress coefficient σ_θ/σ_c, and rock brittleness coefficient σ_c/σ_t. Box-Cox transform and SVM SMOTE oversampling were employed to normalize and balance the rock burst sample data. The processed dataset was then input into the CNN-LSTM prediction model for training and prediction. Subsequently, we gradually optimized the model using Bayesian parameter optimization algorithm and multi-head attention mechanism. Our results demonstrate that Box-Cox transform combined with SVM SMOTE oversampling effectively mitigates the influence of outliers and data imbalance on the model while enhancing dataset separability. Furthermore, the Bayesian parameter optimization algorithm efficiently identifies optimal hyperparameter combinations for our model, while the multi-head attention mechanism improves its prediction accuracy. With these enhancements, we observed an increase in prediction accuracy from 83.33% to 95% for the CNN-LSTM model. The BO-CNN-LSTM-Multihead-Attention classification prediction model established under this strategy exhibits great potential by effectively improving the accuracy of rockburst intensity prediction despite uneven sample data distribution.
- 1
Table 4 Simulation scheme of stage height and top column thicknessAbstract:
A lead-zinc mine adopts the segmented rock-cutting stage ore house method to mine a sharply inclined medium-thickness ore body, and reasonable structural parameters of the quarry are important factors to ensure the stability of the quarry and the profitability of the mine. In order to further improve the profitability of mining, the I ore body of the mine is taken as the research object, and the Mathews stability diagram method is used to analyze the stability of the quarry, and the limit span of the roof enclosure and side gang enclosure is 55.31m and 44m respectively by calculating the stability coefficient and hydraulic radius, which indicates that the current mine house span of 50m is reasonable. Combined with the calculation results of Mathews" diagram method, 9 scenarios with different stage heights and roof thicknesses were formulated, and the numerical simulation studies on the stability of the quarry of the 9 scenarios were carried out by using FLAC3D to compare and analyze the maximum principal stresses, minimum principal stresses, roof displacements, and plastic zone maps of the different scenarios. Through the analysis of the simulation results, we know that the optimization of the roof thickness from 8m to 7m and the stage height of 40m are reasonable parameter configurations, which can not only ensure the stability of the quarry but also improve the profitability of mining, and provide theoretical basis and references for the design and construction of the mine in the future.
- 1
Study on soil reconstruction of a mining area in northwest China based on coal gangue improvementAbstract:
To address the issues of scarce surface soil and inadequate solid waste resource exploitation in the northwest mining region, research was conducted on soil reconstruction technology based on coal gangue discovered there. The Coal Gangue (CG), Rock-Soil strippings (RS), and Topsoil (TS) from a mining area in TongChuan, Shaanxi Province as raw materials were used to constitute a reconstructed soil sample with different proportions, which was conducted for alfalfa (Medicago sativa L.) pot tests. Surprisingly, the results showed that the physicochemical properties of reconstituted soil with different ratios were different. In general, the reconstituted soil increased the content of nutrients and water content, which promoted the growth and development of alfalfa. Compared to the TS, the pH of reconstituted soil decreased by 0.59~1.32 units, organic matter, total nitrogen, and available potassium increased by 6.20~61.63 g·kg-1, 0~0.29 g·kg-1 and 0.50~41.70 mg·g-1, respectively, and effective phosphorus decreased by 0~1.43 mg·g-1. It was shown that CG 40% and RS 15% were the most favorable treatment for alfalfa''s growth, and the highest plant of alfalfa was 54.60 cm, the longest root length was 23.20 cm, and the maximum fresh and dry weight was 14.8142 g and 4.8495 g, respectively. The above results suggest that the reconstructed soil formed with CG as the substrate is feasible for mine phytoremediation in northwest China. The results provides a new option for the comprehensive utilization of CG.
- 1
Optimization and stability analysis of the size of the water-resistant pillar in an iron mine of LuanzhouAbstract:
Hebei Luanzhou iron ore deposits are mostly located in the water-rich and thick lower Quaternary sedimentary metamorphic rocks, and there are large-scale fault structures, so the reasonable determination of the thickness of the Quaternary watertight roof protection pillars and the width of the fault water-resistant pillar is a prerequisite for the safe production of the mines. Taking the typical filling method mining mines in Luanzhou City, Jidong as the engineering background, the optimization of the size of the watertight ore pillars of the mines was carried out through theoretical analysis, and the optimized size was evaluated for stability by using a large-scale finite element numerical computation model. The results show that: the height of the region affected by the maximum value of displacement after designed ore body excavation and filling did not intrude into the lower weathering layer of the Quaternary system; maximum and minimum principal stresses are compressive stresses, no tensile stress areas developed, not exceeding the compressive strength of the surrounding rock, close to the compressive strength of the weathered layer; the weathered rock did not produce a plastic zone of the damage unit. The overall displacement-sensitive area of fault and pillar is distributed in 0~30m; the principal stress in the fault and pillar is compressive, with no tensile stress. Compression stress at fault contact with surrounding rock reaches plastic strength, while the principal stress in the pillar area does not exceed the strength of the pillar; the contact area between fault and pillar, and the contact area between fault and surrounding rock locally develops a plastic zone, and no penetration area is formed. The area of mine above -110m is left to be a roof guard. The mine pillar above -110m meets the requirement of waterproof safe mining of weathered rock layer; when 100m waterproof mine pillar is left on the north side of the fault, and 60m waterproof mine pillar is left on the south side, it meets the requirement of waterproof safe mining. The research methodology and conclusions can provide meaningful reference value for the retention and evaluation of water-resistant pillar during underground mining in similar mines.
- 1
Research on the control technology of upward fan-shaped deep hole blasting pile in underground minesAbstract:
Scientifically and reasonably controlling the blasting pile shape of underground mines is of great significance for improving mining efficiency and ensuring the safety of mining operations. This article focuses on the control of blasting piles in upward fan-shaped deep hole blasting in underground mines. Firstly, the mechanism of the formation of new free surfaces in rock blasting is theoretically analyzed, and the formula for calculating the minimum delay time for the formation of blasting free surfaces is derived; A coupled FEM-SPH model for upward mid deep hole blasting was constructed using LS-DYNA numerical simulation software, and the throwing law of rock blasting with different detonation sequences was analyzed. The results show that the newly formed free surface is basically formed about 15-20 ms after the first blast hole is detonated. The scheme of detonating the middle hole first and the two side holes later can significantly improve the concentration of the explosive pile. The on-site industrial tests and post explosion effects have verified the rationality
- 1
Hydrochemical characteristics and control measures of water gushing in the main and west orebody of Chambishi Copper MineAbstract:
Chambishi copper mine is a typical large water mine in Africa. The hydrogeochemical research of mine water gushing is of great significance for groundwater prevention and control engineering. In this study, 2 groups of surface river samples and 16 groups of mine water gushing were collected. Based on piper three-line graph, ion proportion coefficient, phreeqc simulation and other methods, the hydrochemical characteristics of mine water gushing were analyzed, and the main source and evolution law of the main orebody and the west orebody water gushing were revealed. The results show that the main chemical type of mine water gushing is S04-Ca·Mg water, and the main source of water chemical composition is the dissolution of gypsum and dolomite, and part of the source is the dissolution of feldspar. As the main water filling source, the flint dolomite aquifer is continuous distribution in the region and receives recharge from atmospheric precipitation, surrounding surface rivers and regional groundwater. The groundwater in the mining area flows from the west orebody area to the main orebody area, and the main orebody area is affected by the caving method mining, and the flint dolomite aquifer directly recharges the orebody aquifer. The quartzite water barrier is unevenly distributed, and the thickness of some sections is thinned or missing. Under natural conditions, the flint dolomite aquifer and the orebody aquifer also have a hydraulic connection. Combined with the current situation of the mining area and the chemical characteristics of mine water gushing, the prevention and control countermeasure of "plugging is the main, and drainage is the auxiliary" is proposed, which provides a reliable basis for the underground water safety and production.
- 1
Experimental Study on Mineral Processing of a Low Grade Fine grained Copper Molybdenum Ore in XinjiangAbstract:
In response to the problems of low grade, fine embedded particle size, and difficulty in separating copper and molybdenum in a certain porphyry copper molybdenum mine in Xinjiang, experimental research was conducted on the ore properties and beneficiation process. The principle process flow of "copper molybdenum mixed flotation concentrate regrinding copper molybdenum separation" was determined. Through single factor condition experiments, the key technical parameters of each flotation operation were optimized, and on this basis, a full process closed-loop experiment was conducted. The results showed that the principle of "copper molybdenum mixed flotation coarse concentrate regrinding copper molybdenum separation" process flow was adopted, and the stage grinding stage selection effectively controlled the dissociation degree of the target mineral and reduced the over grinding of the easily slimy gangue mineral. The "one coarse, three fine, two sweep selection" copper molybdenum mixed flotation and "one coarse, seven fine, one sweep" copper molybdenum separation full process closed circuit test obtained copper concentrate with a Cu grade of 23.58%, Mo content of 0.046%, Cu recovery rate of 82.97%, and molybdenum concentrate with a Mo grade of 34.21%, Cu content of 0.96%, Mo recovery rate of 66.38%, achieving effective separation and recovery of copper and molybdenum. This provides a technical basis for the efficient development of copper molybdenum mineral resources.
- 1
A Magnetite Ore Separation Method Based on Fuzzy Wavelet Neural NetworksAbstract:
Magnetic separators are widely used in the pre-selection tailings removal stage of magnetite ore. They utilize Hall sensors to detect the magnetic induction intensity of magnetite ore to determine ore quality, thereby providing a more accurate detection mechanism. However, magnetic sort methods based on magnetic signal threshold segmentation are limited by a single threshold and cannot adapt to variations in ore quality, resulting in low sorting accuracy for weakly magnetic ores. Therefore, for magnetite ore with particle sizes between 20-50 mm, a classification method based on a fuzzy wavelet neural network is proposed. First, feature extraction is performed on the dataset, and the features are fuzzified and quantified. The improved grey wolf algorithm is then used to optimize the initial parameters of the model. The quantified dataset is then input into the optimized network model for training, and the gradient descent algorithm is used to update the parameters of the fuzzy rules to improve the quality of the network model and enhance sorting accuracy. Experimental results show that the optimized network model"s accuracy and F1 score are significantly higher than those of other models, improving by 2.6% and 5% respectively, reaching 0.9667 and 0.9512, while convergence speed improved by 24%.
- 1
Research on on-demand optimized support design and effectiveness evaluation of stope rock roadways based on XGBoost modelAbstract:
In order to avoid the phenomenon of more reinforced support for high-quality rock and less firm support for inferior ones, an intelligent platform system of “on-demand support” based on the big data and artificial intelligence algorithm has been developed on account of the XGBoost algorithm and combined with the empirical formulae of roadway safety factor. Taking 7 on-demand anchor net support indexes and 5 on-demand plain shotcrete support indexes that affect the stability of roadways in Longqiao Iron Mine as the main input values, the 61 roadway practical data have been chosen as examples to carry out the on-demand optimization support design and effectiveness evaluation. The results indicate that: i)The surrounding rock rank performs better and the safety factor manifests larger at the horizontal position of -370.0m, so no support measures can be taken. ii) At the horizontal trial positions of -382.5m and -395.0m, the surrounding rock rank exhibits slightly worse and the safety factor displays mildly lower, so the support form as plain shotcrete should be adopted. iii) The surrounding rock ranks at the horizontal trial positions of -407.5m and -420.0m are all above level 3, whereas the properties of surrounding rock manifests poorer, so it is necessary to adopt the form of anchor net support for all of them. The “on-demand support” intelligent platform system has provided real-time rock mass quality assessment and support scheme optimization for Longqiao Iron Mine, effectively improving the safety and economy of the roadways, which will save the labour intensity and support costs.
- 1
Research and production practice on pharmaceutical system optimization of a copper-cobalt mineral processing plant in the Democratic Republic of the CongoAbstract:
In view of the problems of large dosage of reagents and high cost in the traditional lime-free sodium sulfide flotation process of copper cobalt sulfide ore and sulfur-oxygen mixed copper ore, a study on the optimization and adjustment of the reagent system was carried out with a concentrator in the Democratic Republic of the Congo. The pH value and flotation environment of pulp were adjusted by adding lime to reduce the dosage of Na2S . This process optimization is feasible for both copper-cobalt sulfide ores and sulfur-oxygen mixed copper ores.For copper-cobalt sulfide ores, when the lime dosage is 500~700 g/t, the Na2S unit consumption drops to 312.48 g/t. And the copper and cobalt recovery rates are respectively are 93.38% and 91.82%. For sulfur-oxygen mixed copper ore, when the lime dosage is less than 350 g/t, the Na2S unit consumption drops to 517.35 g/t.And the copper recovery rate is 86.01%. Compared with previous optimization, the reagent cost per ton of copper and cobalt sulfide ores was reduced from the original US$1.77/t to US$1.58/t, a decrease of 10%. The cost of sulfur-oxygen mixed copper ores was reduced from the original US$2.12/t to US$1.74/t,a decrease of 18%.Both of them have good effects of reducing cost and increasing efficiency.
- 1
Research and Application of Data-driven Intelligent Operation and Maintenance System for Mining Truck Drive SystemAbstract:
Aiming at the problems such as the difficulty of diagnosing the drive system of mining trucks, we integrate wavelet packet and ensemble empirical modal decomposition methods, and propose an intelligent fault diagnosis model with multiple swarm genetic algorithms to optimise the support vector machine, which is integrated into the intelligent operation and maintenance system and applied to mining trucks. Firstly, the vibration signals of gears and bearings in the drive system are noise reduced using wavelet packets, and then the signals are decomposed into several intrinsic modal function (IMF) components by ensemble empirical modal decomposition, and the feature vectors are obtained by extracting them from the IMF components that contain the main state information; secondly, the failure modes are classified using the support vector machine, and the support vector machine is optimised by particle swarm, genetic algorithm and multiple swarm genetic algorithms. The four kinds of fault diagnosis models, namely, SVM, SPO-SVM, GA-SVM, MPGA-SVM, are constructed by particle swarm and multiple group genetic algorithms, and the optimal fault diagnosis model is obtained by analysing the penalty parameter C and kernel function parameter g of the support vector machine. Finally, for the RE1060 drive system of XDE320 electric-driven mining dump truck, a set of signal acquisition and storage, time-frequency analysis, fault analysis, fault diagnosis model, and fault diagnosis model are developed by using MATLAB and LabVIEW. Finally, for XDE320 electric-driven mine dump truck RE1060 drive system, a set of intelligent operation and maintenance system containing four modules of signal acquisition and storage, time-frequency analysis, fault feature extraction and intelligent fault diagnosis is developed using MATLAB and LabVIEW. The study shows that the system can realise online monitoring and diagnosis of existing faults, which is of great significance to improve the safe and efficient operation of mining trucks.
- 1
Research on a Level Track Locking Device for Inclined Shaft Skip Hoist Runaway PreventionAbstract:
In order to solve the problems of slow response speed, large positioning error, and susceptibility to external interference in the terminal servo drive system of mining operation robots,Propose a finite time stabilization control method that combines nested saturation control with integral sliding mode control. Establish a third-order linear uncertain system model of DC servo drive with external interference, based on the integral sliding mode design concept, introduce nested saturation control, and enable the system state output to reach the sliding mode surface and stabilize in finite time, achieving fast and accurate control of the output angular velocity of the terminal servo DC motor. The stability of the finite time stabilization control method has been proven through theoretical analysis, and simulation experiments have verified that this control method not only improves the response speed and control accuracy of the servo DC drive system, but also reduces the influence of external interference, significantly improving the stability of the system.
- 1
Modeling of downhole dust concentration prediction based on NRBO-RFAbstract:
The high concentration of mine dust seriously jeopardizes the physical and mental health of miners and environmental safety, and dust prediction is of great significance for intelligent dust prevention and reduction. In order to achieve accurate prediction of dust concentration in mines, a multifactor dust concentration prediction model is constructed by using the on-site monitoring data of the coal mining face in a mine in Shaanxi Province, using the random forest algorithm with temperature, humidity, wind speed, and the dust concentration at the moment of t as the input features; and it is proposed that the four intelligent optimization algorithms (Newton-Raphson optimization algorithm(NRBO), Sparrow optimization algorithm, Gray Wolf optimization algorithm, and Whale optimization algorithm) be used for the Random Forest parameters (number of trees and number of leaf nodes) for optimization, and evaluating the model"s merits through R2, RMSE and MAE. The results show that the optimal model for dust concentration prediction is the random forest model with Newton-Raphson optimization; the random forest model optimized by the NRBO algorithm improves the prediction results by 3% in R2, reduces the RMSE by 58%, and reduces the MAE by 7.5% than the conventional random forest model, and it has the highest fitting ability and prediction accuracy. The results of the study can provide a reference for the intelligent prediction and prevention and control of mine dust.
- 1
Research and application on optimization of fan-shaped borehole blasting parameters of sublevel caving under broken rock mass and ore-bodyAbstract:
The quality of fan-shaped borehole blasting is very important for the application of sublevel caving mining method. It is of great significance to study the parameters of fan-shaped borehole blasting under different rock mass conditions. This article focuses on the problems of severe damage to the eyebrow line, uneven blasting block size, and large ore loss and dilution when using the sublevel caving mining method in the West Second Mining Area of Longshou Mine under broken rock mass condition. ANSYS/LS-DYNA was used to optimize the fan-shaped borehole blasting parameters in the sublevel caving mining method. The research results show that under broken rock mass condition, the "W" - shaped staggered charging structure is better than the large-area non-charging structure at the hole opening, the bottom blasting is better than the hole opening blasting, and the in row segmented micro delay blasting is better than the in row simultaneous blasting. Finally, a fan-shaped hole blasting scheme was proposed with a "W" shaped staggered charging structure at the hole opening, bottom blasting, and segmented micro delay blasting between rows. Field industrial experiments were conducted, and the results showed that the optimized fan-shaped blasting parameters increased the ore recovery rate in the mining area by about 36%, reduced the ore impoverishment rate by about 31%, and reduced the large block rate by 52%. In addition, the damage to the eyebrow line was also significantly improved. The research results can provide reference for deep hole blasting in similar broken rock.
- 1
Research and Engineering Practice on Basic Digitization Technology of Open-Pit minesAbstract:
In alignment with Zhejiang Province's initiative to comprehensively advance the digitalization of mines, by driving the digitalization, transformation, and modernization of mining operations, this initiative seeks to propel the high-quality and efficient development of mining enterprises.In response to the digitalization requirements for foundational systems in small and medium-sized open-pit mines, introduces and integrates modern information technologies such as 3D real scene, digital twins,Internet of Things (IoT) , and artificial intelligence (AI).It conducts an in-depth analysis and study of system architecture, key technologies, and core modules. As a result, a mine foundational digital management system capable of cross-temporal, full-cycle, and multi-domain data integration has been constructed. This system has been applied and tested in several small and medium-sized open-pit mines in Linhai and Wenling cities of Zhejiang Province, demonstrating its effectiveness and potential for broader industry adoption.Simultaneously, its robust data integration capabilities and intelligent management have propelled mining enterprises through a transformation from “fragmented” management to “integrated”management. This transition has realized the conversion of data resources into data assets, guiding companies to shift from conventional thinking to modern systemic thinking. Moreover, it has provided a model of reference and demonstration for the digitalization of small and medium-sized mines not only across the province but also nationwide. This contributes to further enhancing the levels of digitalization and intelligence in mining.
- 1
Application of RSM-BBD in optimizing the proportion of slag based fully tailings cemented filling materialsAbstract:
To reduce the cost of backfill mining, slag powder cement is used as a composite cementitious material, and the response surface methodology is employed to obtain the optimal ratio of backfill material that meets the requirements of mine backfill strength. Firstly, by conducting strength tests on fillers with different cement to sand ratios (slag powder cement: tailings) and slump tests with different mass concentrations, the slag powder ratio and mass concentration range were preliminarily determined; Then, based on the RSM-BBD module, a regression model for the strength of slag based cemented filling materials at different ages was established to analyze the relationship between slag powder content, cement sand ratio, and slurry concentration on the strength of cemented filling materials; Finally, based on the engineering requirements, the optimal ratio of filling materials is recommended, and the economic benefits are analyzed and compared. The results show that; The interaction between slag powder dosage and slurry concentration, slag powder dosage and cement sand ratio, and cement sand ratio and slurry concentration has significant effects on the 3D strength, 7d strength, and 28d strength of the filling material, respectively; The recommended ratio can meet the strength requirements of mining methods and has considerable economic benefits.
- 1
Study on the influence of floor cavity on the stability of the roadway and support methodAbstract:
When there is a cavity in the surrounding rock of the roadway, the stability of the roadway is usually adversely affected. Under the influence of filling cavity under the floor, the final sublevel stope of Longshou Mine in Jinchuan has a significant deformation and failure, which seriously affects the normal production of the stope. Through field investigation, numerical simulation and field test, the failure mechanism and support mode of the mining approach are studied. The research results show that the deformation of the cavity near the approach under the action of stress concentration leads to the collaborative deformation of the surrounding rock of the approach, and the existence of the cavity provides the development space for the large deformation of the surrounding rock, which is the main reason for the serious damage of the approach. Then, according to the location of the cavity and its control effect on the stability of the mining approach, an asymmetric support scheme is proposed. In this scheme, the filling cavity is regarded as the weak point of the whole supporting system to impose support, so as to reduce the adverse influence of the cavity on the stability of the mining approach. The application of asymmetric support scheme in the field has achieved good support effect, reducing the deformation of the approach by more than 80%, reducing the support cost by about 11.7%, improving the safety of the stope and ensuring the normal production of the stope.
- 1
Study on Preparation and Mechanism of Geopolymer from Iron Ore Tailings by Thermal-chemical ActivationAbstract:
Iron ore tailings (IOT) are the solid waste of iron ore after mining and processing in concentrator to produce iron concentrate powder. In order to solve the technical bottleneck of low reaction activity and limited usage of IOT in preparation of geopolymers, IOT-based geopolymers were prepared from high-silica IOT and low-silica IOT as the main raw materials, metakaolin as the correction material and water glass as the alkali activator. The thermal-chemical activation was used to activate the activity of IOT. The XRD and SEM/EDS were used to analyze the changes in mineral composition of IOT before and after activation, and the effects of activation mode on the morphology and structure of geopolymers. The results show that the reactivity of IOT after thermal-chemical activation was significantly increased, and the geopolymers have dense internal structure and the compressive strength increased significantly. The suitable thermal-chemical activation temperature is 500℃. At the same thermal-chemical activation temperature, IOT with a fineness of 10% exhibit the highest activity and the geopolymers prepared from them have the highest compressive strength. Compared with low-silica IOT, high-silica IOT can obtain higher reactivity after thermal-chemical activation, and the geopolymers prepared from high-silica IOT have higher compressive strength. Thermal-chemical activation causes partial transformation of low activity minerals in IOT, forming highly active minerals such as soluble sodium silicate and metastable amorphous substances.
- 1
Research on the Support Technology of the Trapezoidal Tunnel in the 105 Working Face of Toksun Coal MineAbstract:
In order to address the challenges posed by easy instability, difficulties in providing support, and high support costs during trapezoidal roadway tunneling, a supporting scheme for the 105 working face roadway is proposed based on theoretical analysis and numerical simulation methods, with Toksun Coal Mine serving as the research background. This proposal builds upon the existing 104 working face roadway support scheme and is validated through measured data. Research results indicate that under the existing support conditions, the mine pressure behavior of the roadway in 104 face is not obvious, and the surrounding rock mass is stable and does not produce a large scale separation phenomenon. On this basis, the support of 105 face can be carried out. Compared with the theoretical analysis value, the existing support scheme is conservative, there is a certain optimization space, it can be optimized design. The optimized support scheme has weakened the control strength of the roof and two walls of the roadway, and the displacement reduction is reduced from 59 mm, 46 mm and 56 mm in the existing scheme to 41 mm, 43 mm and 43 mm, but the support cost is reduced by 32.5%. Moreover, the measured data shows that: The deformation of the roof and its two sides is 19.6 mm, 21.2 mm and 26.8 mm, respectively. After the workface is mined back, the roadway and surrounding rock of the working face are relatively stable, and there is no occurrence of large energy microseismic events, which indicates that the optimized scheme can meet the safety requirements of the roadway excavation and mining of the working face.
- 1
Research on comprehensive performance of modified materials for cement stabilized base of open-pit mine transportation roadAbstract:
To address the issues of durability and poor water stability of traditional gravel transport roads in open-pit mines, mine solid waste from surrounding areas was utilized for road modification. Laboratory tests determined the optimal ratio of blasting waste rock to surrounding soil in the cement-stabilized base, and the strength, water stability, and durability of the base with various curing agent contents were investigated. The study revealed that unmodified pavement had an unconfined compressive strength lower than 0.2 MPa, indicating insufficient performance. When the ratio of blasting waste rock to roadside soil was 4:6, the waste rock's strength was fully utilized, resulting in a well-structured pavement. The addition of curing agents significantly enhanced the material's strength. Specifically, an 8% curing agent content resulted in an unconfined compressive strength exceeding 2.5 MPa and a water stability coefficient of 137.68%. The saturated compressive strength surpassed the initial value. After 9 cycles of dry-wet testing, the compressive strength initially increased significantly with each cycle, then slightly decreased, stabilizing at 7 MPa. Following the laboratory tests, industrial tests were conducted using a 4:6 stone-soil ratio and an 8% curing agent content. Deflection value tests and comprehensive cost analyses were performed at Zijinshan Gold-Copper Mine. The findings indicated that the deflection value of the modified pavement was 9.07 (0.01 mm), demonstrating a significant improvement in road quality, with a comprehensive cost of 47.5 yuan/ m2, significantly reducing overall costs.
- 1
Acoustic Emission Based Brazilian Bisc Test with Different Inclination Cracks and Its Numerical Simulation StudyAbstract:
In order to study the mechanical and acoustic properties of prefabricated cracked rocks with different inclination angles on the prefabricated cracked rocks, as well as the crack extension mechanism and rupture mode during the rock rupture process, Brazilian disc tests were carried out by prefabricating disc specimens with different inclination angles of cracks, and observations and analyses were carried out by acoustic emission technology and extended finite element method to investigate the rupture evolution law of the rocks under the cracks with different inclination angles. The results show that, with the increase of inclination angle, the crack initiation location shifts from the tip of the prefabricated crack to the middle, and the rock initiation load, peak load and other parameters firstly decrease and then increase; the acoustic emission parameters show that the specimens show various damage modes with the difference of inclination angle: the specimens with medium inclination angle mainly undergo shear-tensile damage, while the rest of the specimens undergo mainly tensile splitting damage. The acoustic emission correlation results are consistent with the trend of bearing capacity with prefabricated crack inclination α. The XFEM simulation results are consistent with the experimental observations, confirming the effectiveness of this numerical method in predicting rock crack extension. The results of the study help to predict and control the fracture behaviour of rock bodies in mining, tunnel boring and other fields during engineering operations, and provide an effective reference for solving engineering safety problems in the industry..
- 1
Strength Characteristics and Stability Analysis of Surrounding Rock in Roadway Filling Mining AreaAbstract:
With the exhaustion of shallow resources, deep shaft mining may become the norm for the development of deep mineral resources in China in the future. In order to explore the influence of the layout direction of the access mine on the stability of the mine under the high geo-stress conditions in the deep part of the mine, the access mine at the depth of 1000 m in the mine was taken as the object of the study, and drill hole coring and uniaxial compression and Brazilian splitting tests were carried out. Based on the empirical formula of the Hawke-Brown criterion, the mechanical parameters of the surrounding rock mass were obtained, and the numerical simulation study of the approach mining was carried out. The influence of the main stress direction on the stress distribution, damage area and damage process of the peripheral rock in the approach mining site was explored to optimize the approach arrangement scheme. The test results show that the average uniaxial compressive strength, tensile strength and modulus of elasticity of the rock layers in the ore body of mine in the range of 1000m burial depth are 96.48MPa, 3.92MPa and 33.87GPa, respectively, and the peripheral rock has obvious brittle characteristics. The direction of approach arrangement has a significant influence on the stability of the quarry, which is mainly reflected in the size of tensile stress concentration area and plastic deformation area. The simulation results found that with the increase of the angle between the approach direction and the main stress direction, the stress concentration phenomenon is more and more obvious, and the range of plastic deformation of the surrounding rock also increases. When the approach direction is parallel to the main stress direction, the stability is the best. Based on the numerical simulation results, the mechanical mining industrial test was carried out with the main stress direction as the working direction. And the size of the mine approach was explored to be expanded to 4*4m, and it was found that the stability of the approach mine was good under the smaller operational disturbance of mechanical mining.
- 1
Optimization of flotation of copper ions by biological collector based on response surface methodAbstract:
A novel biodegradable surfactant sodium N-lauroyl sarcosinate (LS) was used for copper ion flotation. The effects of mass ratio of LS to Cu(II)( ρ(LS):ρ(Cu (II))), pH value of solution and flotation time on the flotation effect of copper ion were explored by single factor condition test, and the conditions were optimized by Box-Behnken response surface method. Finally, the verification test was carried out based on the optimization results. The following conclusions are drawn : The results of single factor test showed that ρ(LS):ρ(Cu (II))= 2.5, pH = 8, flotation time 3min was the best condition, and the removal rates of Cu(II) were 95.57 %, 98.42 and 96.83 %, respectively. The verification test results show that the average removal rate of Cu(II) in the three verification tests reaches 99.71 % when ρ(LS):ρ(Cu (II))= 2.5, pH = 9, flotation time 4min, which is basically consistent with the prediction results obtained by software fitting, indicating that the model has good fitting degree and reliability. The morphology and elemental analysis showed that the structure of LS-Cu complex was loose and stable. Compared with LS, the weight concentration percentage of Cu(II) in the complex increased from 0.00 % to 5.15 %, indicating that LS had better adsorption capacity for Cu(II).
- 1
Experimental Sudy on Dnamic Mchanical Poperties of Hgh-Tmperature-Wer-Coled Prous-Baring Sndstone SecimensAbstract:
To explore the effect of water cooling on the dynamic compressive mechanical properties of high-temperature porous sandstone, XRD and SEM tests were carried out on natural and high-temperature-water cooled porous sandstone specimens at 200°C, 400°C, 600°C, 800°C and 1000°C. It is found that the natural sandstone has a dense structure, and the main mineral components are quartz and calcite, which are gradually decomposed into calcium oxide by high temperature-water cooling, and calcium hydroxide is formed when exposed to water, and the section is covered with micron-sized particles. With the increase of action temperature, the color of the specimen gradually changed from gray-white to brown, the volume expanded, and the mass, density and longitudinal wave velocity decreased. The variation law of different high-temperature-cooling dynamic stress-strain curves is similar, which can be divided into three stages: elasticity, plasticity and failure. The dynamic compressive strength was negatively correlated with the operating temperature, and the dynamic strain and the average strain rate were positively correlated with the operating temperature. With the increase of action temperature, the impact and crushing degree of the specimen intensified, and the average particle size of the fragments was negatively correlated with the quadratic function, and the damage changed from several fragments to powder. Compared with the high-temperature-naturally cooled porous sandstone specimens, the dynamic compressive strength and average particle size of the specimens decreased, and the dynamic strain and average strain rate increased. The internal structure of the sandstone specimen is damaged by high temperature-water cooling, and the more serious the structural damage and deterioration with the increase of the action temperature, the more obvious the kinetic decline becomes.
- 1
Study on the shaking table test of tailings pond drainage wellAbstract:
Drainage well is an important safety facility of tailings pond, and its stability is related to the safety of tailings pond. Based on the similarity principle, the dynamic response characteristics and variation law of the tailings pond drainage well under different seismic acceleration and different buried depth conditions were systematically studied by shaking table test. The results show that : (1) In the process of increasing the seismic acceleration peak from 0.315g to 1.5g, the acceleration amplification coefficient in the drainage wellbore ( model ) increases first and then decreases, and the wellbore gradually changes from elastic to elastic-plastic, and the stiffness gradually decays ; (2) Under the action of the peak acceleration of 1.5g earthquake, the maximum relative displacement of the drainage well under the full burial condition is 0.967mm, which is much smaller than the maximum relative displacement of the drainage well under the non-buried condition of 5.295mm. It shows that the tailings around the drainage well play a stabilizing role in the drainage wellbore under the action of earthquake, which can improve the seismic performance of the drainage well. (3) When the peak value of seismic acceleration increases from 0.315g to 1.5g, the first-order frequency of the drainage well (model) decreases by 29.17 %, 27.05 % and 22.74 % respectively compared with the initial natural frequency under the conditions of non-buried, semi-buried and full-buried, and the stiffness of the drainage well degrades fastest under the condition of non-buried. (4) Under the action of earthquake, the strain values at different positions in the wellbore are positively correlated with the distance from the top of the drainage well. The maximum strain appears at the bottom of the drainage well, indicating that it is most vulnerable to vibration damage. The seismic performance of the bottom of the drainage well should be strengthened in the design.
- 1
Synergistic effect of OP-10 and PEO to enhance the flotation of high-ash fine-grained coal slurry and its mechanismsAbstract:
The recovery of high-quality carbon components from high-ash fine coal slime through flotation can achieve efficient and sustainable resource utilization. This paper focuses on high-ash fine coal slime as the research object, using a composite pre-treatment of octylphenol polyoxyethylene ether (OP-10) and polyethylene oxide (PEO), comparing it with single reagent pre-treatment flotation. It was found that the two reagents significantly enhanced the floatability of the coal slime through synergistic effects. Based on this, the mesoscopic mechanisms were analyzed using laser particle size analyzers, contact angle meters, Fourier-transform infrared spectroscopy (FTIR), Zeta potential analyzers, and atomic force microscopy (AFM). The results indicate that due to competitive adsorption, PEO preferentially adsorbs onto the coal surface through polar interactions, exposing alkyl chains and enhancing some hydrophobicity. It also compresses the hydration layer on the coal slime surface, reducing electrostatic repulsion between interfaces and promoting the agglomeration of fine coal particles into small flocs. After the action of PEO, OP-10 begins to adsorb onto the surface of the flocs, compressing the double electric layer and shielding electronegative ions. Additionally, due to the reduced specific surface area, it is easier to cover the coal slime compared to the initial fine coal, and the adsorption layer is more uniform and thicker than that from single reagent addition. OP-10 primarily adsorbs through polar interactions between the oxygen in its chain structure and the —OH and C—O—C functional groups on the coal surface, wrapping its chain structure around the coal surface and covering the oxygen-containing functional groups of the coal sample. Meanwhile, OP-10 may also rely on the hydrophobic and van der Waals forces from its alkyl chains to adsorb on the coal surface. After the adsorption of the two ends of the reagent structure, the aromatic hydrocarbon part is exposed on the coal surface, demonstrating the most obvious hydrophobic modification effect. Overall, the composite reagents enhance the hydrophobicity of the coal sample through single-layer and double-layer adsorption via electrostatic and polar forces, significantly reducing adhesion and greatly improving flotation efficiency.
- 1
Improved Mine Fire Detection Algorithm for YOLOv8nAbstract:
Mine fire is one of the key points of mine safety. To resolve the inefficiency of traditional fire detection algorithms and the challenges of deploying them on embedded devices which is resource-constrained, a lightweight algorithm for fire detection with improved YOLOv8n is proposed. Firstly, for the purpose of greatly reducing the quantity of model’s parameters, the C2f module in the YOLOv8n model is changed to the C2fGhost module. Secondly, in order to against the loss of critical features after the model is lightweight, enhance the capability of feature extraction and reduce the disturbance of irrelevant information in the image, the EMA attention mechanism is added to the Backbone part of the YOLOv8n model. Finally, to enhance the model's generalization capability, the CIoU loss function in the YOLOv8n model is substituted with WIoU. Experimental outcomes indicate a 30.1% reduction in the number of parameters in the improved model, a 0.6 percentage points increase in mAP50-95, and only a 0.2 percentage points decrease in accuracy. The improved model can detect underground fires in real time and efficiently, and the detection algorithm has reference value for management of mine safety.
- 1
Experimental Study of Backfill Materials Prepared from Cement and CFBFAAbstract:
In order to solve the problem of low comprehensive utilization rate of circulating fluidized bed fly ash (CFBFA), backfill materials are prepared by adding a small amount of cement with CFBFA as the main raw material. The differences in physical and chemical properties between CFBFA and FA were compared. On this basis, the control variable method was used to explore the effects of concentration, dosage of cement and admixtures on the fluidity, bleeding rate and compressive strength of backfill materials. In addition, The engineering test was carried out based on a coal mine backfilling project in Shanxi. The experimental results show that the CFBFA has strong water demand and high activity. The concentration and cement dosage are the key factors affecting the performance of the backfill materials. The concentration of backfill materials is positively correlated with compressive strength, and negatively correlated with the fluidity and bleeding rate. With the increase in dosage of cement, the fluidity, bleeding rate and strength increase. Without admixtures, when the cement dosage is 200kg/m3 and the concentration is not more than 0.555, the fluidity and strength of the backfill material meet the requirements, however the bleeding rate cannot fall below the requirements,2.0 %. The appropriate dosage of the admixtures is 5kg/m3, that can significantly improve the fluidity of the backfill material, lower the bleeding rate, and reduce the amount of cement up to 90kg/m3. The engineering test shows that after adding the admixtures, the mixability and pumpability of the backfill material are obviously improved. The backfill material prepared on site according to the admixtures 5kg/m3, concentration 0.595, cement 120kg/m3 ratio meets the engineering design requirements.
- 1
Study on Mechanical Properties and Acoustic Emission Response of Different Initial Damage SandstonesAbstract:
In In the construction and production process of open pit mines, tunnels, highways and other projects, it is bound to cause different degrees of damage to different areas of surrounding rock, which will eventually lead to changes in the mechanical properties of surrounding rock. In order to explore the influence of different initial damage levels on the mechanical properties and acoustic emission characteristics of sandstone, the characteristic stress value of sandstone is determined by analyzing the acoustic emission impact parameters during the loading process of sandstone samples, and according to the different multiples of the difference between cracking stress and damage stress, The pre-loads of 42 Mpa, 47 Mpa, 52 Mpa and 57 Mpa are defined as first-class damage, second-class damage, third-class damage and fourth-class damage, respectively. Uniaxial compression tests with acoustic emission monitoring system are carried out on four kinds of sandstone with different initial damage. The analysis results show that: (1) The initial damage has a significant impact on the mechanical properties of the rock. With the increase of the initial damage degree, the compressive strength and elastic modulus of the rock sample decrease by 33.6% and 43.4%. (2) The acoustic emission characteristic signals of sandstone with different initial damage grades are in good agreement with the stress-strain curves, and with the increase of initial damage grades, the local acoustic emission signal suddenly increases obviously; (3) With the increase of damage grade, the crack failure mode of rock changes, from tensile failure of undamaged rock samples to tensile-shear mixed failure.
- 1
Mineral Identification System Based on Orange PiAbstract:
In response to the current challenges of low accuracy, inefficiency, poor real-time performance, and weak environmental adaptability in ore detection technology, a novel ore detection system based on Orange Pi is proposed. This system utilizes a high-definition camera to capture real-time images of ores and processes image data using the YOLOv4-tiny-tf2 model on the Orange Pi 5B development board to achieve efficient and accurate identification of ore types. Experimental testing demonstrated a correct recognition rate of 93.75%, indicating high reliability and stability. The practical application of this ore detection system can be widespread in mining and smelting facilities, aiding workers in rapid identification of ore types and providing robust support for production decision-making. Furthermore, the system"s compact size, low power consumption, and cost-effectiveness make it suitable for deployment at mining sites.
- 1
Experimental study on mechanical cavitation for pressure relief and permeability enhancement in bedding drilling of outburst coal seamAbstract:
Pre-extraction through bedding drilling is a primary method for preventing coal seam outburst in mining faces. However, in China, many outburst coal seams have low permeability, leading to ineffective gas extraction and severely hindering the implementation of this technique. Addressing this issue, a mechanical cavitation pressure relief and permeability enhancement equipment system and process flow for bedding drilling has been proposed based on the conditions of pre-extraction through bedding drilling at the 15111 working face of Sijiazhuang Company. The research investigates variations in coal seam stress and gas content around mechanical cavitation drilling, revealing the impact of drill hole diameter on coal seam pressure relief and permeability enhancement patterns. Process parameters for mechanical cavitation drilling at the 15111 working face are determined. Subsequently, industrial trials on mechanical cavitation pressure relief and permeability enhancement in return airways at the 15111 working face were conducted. Results demonstrate that mechanical cavitation through bedding drilling increases the exposed area and pressure relief range of the surrounding coal body, thereby enhancing the radius of gas extraction influence. The gas extraction volume from mechanical cavitation drilling is more than 8 times that of conventional bedding drilling, with the gas extraction volume fraction increasing by 153.4% compared to conventional bedding drilling, indicating a significant enhancement in permeability. The research findings provide valuable empirical references for regional outburst prevention in mines under similar conditions.
- 1
Design and optimization of open-pit to underground mining method in Sijiaying Iron MineAbstract:
The reasonable selection of the mining method is of great significance to the safe and efficient transition to underground mining operations. In view of the many difficulties in the selection of mining methods for transitioning from open-pit to underground mining in the Sijiaying Iron mining area, based on the complex deposit characteristics and technical constraints of the mining surface environment, the traditional staggered layout of ore transportation is proposed to change the two mining methods for open stope caving and subsequent filling methods proposed in the design. The optimization results show that the mining method optimization scheme using the combination of in-stage scraper and in-pit truck can effectively shorten the transport distance of the scraper and improve transport efficiency. When the height of the optimized scheme stage is 60 m, the height of the ore pass in the mining area is reduced by 30 m, and the number of ore passes in the disk area is reduced from the original 6 to 2, which reduces the production quantity and is conducive to reducing the mining cost. The problems to be considered in selecting and implementing the mining method are pointed out to guide the Sijiaying Iron Mine in converting from an open pit to an underground mine.
- 1
Experimental Study on Mineral Processing of a High Sulfur Hematite abroadAbstract:
A high sulfur hematite from abroad contains 5.68 % S and 45.95 % Fe, with iron mainly occurring in hematite and sulfur mainly present in the form of sulfides. In order to determine the optimal beneficiation process for the mine, based on the study of the properties of the raw ore, experiments were conducted using the grinding-flotation sulfur separation-high magnetic separation iron separation process. The results show that the process can ultimately obtain sulfur concentrate with a sulfur content of 41.31 % and a sulfur recovery rate of 69.73 %, and iron concentrate with an iron content of 60.84 % and an iron recovery rate of 76.92 %. The sulfur impurities in the iron concentrate meet the quality standards
- 1
Optimization of Mining Plans Considering Carbon Performance under the "Dual Carbon reduction ” GoalsAbstract:
The development of mineral resources not only provide a material foundation for the development of the national economy, but also serve as a key battlefield for carbon reduction under the dual target of peak carbon emissions and carbon neutrality. In order to achieve low-carbon development of mines, a weighted grey correlation analysis model considering carbon performance for mining scheme optimization was constructed by introducing carbon performance related indicators of mine to promote carbon reduction at the source on the basis of previous evaluation indicators for mining scheme optimization. Taking a domestic mine as an example, carbon performance related indicators such as average carbon performance were introduced in addition to safety, economic and technical indicators. The weights of each indicator were comprehensively determined by game theory. Open-pit mining by layered stepped method was determined as the optimal scheme from four mining schemes such as underground mining by stage room subsequent filling method, open-pit mining by layered stepped method, combined mining(open-pit mining by layered stepped method in 35% areas and underground mining by stage room subsequent filling method in other remaining areas) and combined mining(open-pit mining by layered stepped method in 60% areas and underground mining by stage room subsequent filling method in other remaining areas) Moreover, the introduction of carbon performance indicators has changed the weighted grey correlation degree of each scheme,compared with the optimization results without them, proving that considering carbon performance indicators under the "dual carbon reduction " goals has great significance and meets the requirements of green mining development. It can serve as a reference for the optimization of mining schemes under the "dual carbon reduction " goals.
- 1
Research on the Application of Hidden Disaster Investigation and Prevention Measures in Open-Pit Iron Mine GoafAbstract:
In response to the technical difficulties of underground goaf detection, complex disaster causing factors, and incomplete prevention and control measures during the underground to open-pit mining process of Yuanjiacun Iron Mine, based on geological data analysis, multiple methods such as geophysical exploration, drilling, and 3D laser scanning were used to accurately detect the abnormal distribution range and occurrence location of goaf areas with a span greater than 5m within a 50m range of the open-pit mining site. The three-dimensional shape and distribution law of the goaf area were obtained, and the stability of the goaf roof was calculated and studied through various methods. The risk assessment of the goaf area was carried out, and the treatment methods and timing of each goaf area were determined.
- 1
Progress and Development Trend of Key Technical Equipment of Lifting for Large-Scale Deep Wells in Metal MinesAbstract:
In recent years,with the depletion of shallow mineral resources,underground metal mines in China have been developing towards large-scale deep wells with a depth of over 1500m and an annual output of over 10 million tons per year. The hoisting system is a major and crucial equipment for deep mining in mines，The existing lifting technology is unable to meet the needs of large-scale deep well mining in China. Therefore, this paper reviews the current research status of key theories and technical equipment in two main research directions of large-scale deep well hoisting, namely friction hoisting and multi-rope winding hoisting, and analyzes the technical advantages and characteristics of each. It also proposes that the continuous lifting, reducing the lifting volume through the integrated mining-processing-filling, and reducing the weight proportion of the lifting carrier are key research directions and development trends for addressing the lifting needs of large-scale deep mining in the future,in order to provide a new lifting system solution for large-scale mining of deep Wells in metal mines.
- 1
Research on Large-Scale Stoping with ConcurrentBackfilling and Continuous Ore Extraction Techniques in Deep Hard Rock Underground MinesAbstract:
Large-scale continuous mining of deep ore bodies represents a frontier research direction in the “deep earth” mining of the future. To address the issue of traditional intermittent mining operations in deep hard rock deposits, which hinder the integration of intelligent and efficient deep mining, a parallel mining-filling continuous operation mode is proposed. This mode utilizes flexible isolation layers to achieve a parallel filling and continuous ore extraction process. Furthermore, theoretical calculations combined with Flac3D numerical software were employed to analyze the strength distribution of the filling bodies in the high-stage large stopes using the parallel filling method, determining the strength requirements for filling bodies at different heights within the high-stage stopes. Finally, the PFC discrete element software was used to analyze the flow behavior of “ore-fill” bulk materials and the deformation and damage characteristics of the isolation layer during parallel filling and continuous ore extraction. The results indicate that in the parallel filling and continuous ore extraction process, the 28-day compressive strength of the filling bodies at the top and bottom of the stope should exceed 8 MPa. As filling and ore extraction proceed, the maximum load on the isolation layer near the ore drawpoint reaches 57 KPa, causing significant concave deformation and increased damage near the side pillar areas, resulting in noticeable tensile and compressive failures. This study provides both practical and theoretical references for continuous operations in the mining of deep ore bodies.
- 1
Lightweight Underground Pedestrian Detection Model Based on YOLOv8Abstract:
In response to the problem of large computation and slow detection speed of the current pedestrian detection algorithm in underground mines, a lightweight underground pedestrian detection model named MBE-YOLO was proposed based on YOLOv8n. The model aims to reduce computing resources and memory consumption, improve real-time detection performance, and provide an advantage for model deployment on edge devices in underground environments. Firstly, a lighter neck structure was designed based on the weighted bidirectional feature pyramid network, with the goal of efficiently fusing multi-scale information. Secondly, the detection head of the original network was redesigned using shared convolution, and the phantom convolution was introduced to obtain rich and effective feature representations, thus solving the problem of the huge number of parameters in the original detection head. Finally, considering the impact of lightweight model on accuracy, a lightweight hybrid local channel attention mechanism was added, which adaptively adjusts the importance of different regions at the global and local levels to improve accuracy. Experimental results show that compared with the benchmark model YOLOv8n, the mAP@0.5:0.95 of MBE-YOLO was improved by 0.2 percentage points, the computational cost was reduced by 44%, the FPS was increased by 4.3 frames/S, the number of parameters was reduced by 46%, and the model size was reduced by 43%. This model has good application prospects for the intelligentization of mines.of mine.
- 1
Study on the reasonable parameters of blasting along the hard roof of the gob-side roadwayAbstract:
The premature collapse of the hard roof along the face side will cause the stress concentration on the roof and the solid coal side, threatening the safety production of the working face, which at present is often weakened by blasting. In this paper, the relationship between the blasting angle, height and pressure relief effect along the top plate of the face is investigated by theoretical analysis, numerical simulation and field practice with the background of 6305 working face of Xin Julong coal mine. The results show that the angle of blasting should be higher than the angle of the rupture line and to avoid blasting the roof plate pressure on the top of the coal pillar, the larger the angle in this area, the more appropriate decompression effect; towards the height of blasting to reach the top of the combination of sub-critical layer can play a more in line with the actual decompression effect of the project; On-site practice from the angle of micro-vibration and drilling debris showed that in the appropriate choice of parameters along the top of the empty lane blasting can effectively reduce the impact of danger, ensure the safe production of working face The research results can be used in mines with similar conditions. The research results can provide theoretical and engineering guidance for similar conditions of the mine.
- 1
Ecological restoration planning design and practice research of abandoned open pitAbstract:
Abandoned open-pit mining sites have caused serious damage to the ecological environment of the mining area and its surrounding areas, leading to a series of problems such as geological disasters, soil erosion, and landscape damage. Carrying out ecological restoration and management work on abandoned open-pit mining sites is not only an effective means of building green mines, but also an important way to promote the sustainable development of resource-based cities. Taking a stone mining area in Chifeng City as the research background, this paper analyzes the current situation, main problems, and hazards of abandoned open-pit mining sites in the area. Targeted governance models and design ideas suitable for the area are proposed, and detailed discussions are conducted on the 7 engineering deployments and corresponding main technical measures involved in the implementation process of the project. The research results indicate that the treatment technology for abandoned open-pit mining sites is difficult and the success rate of ecological restoration is low, especially in areas with exposed slopes and rock walls, which require increased research depth and treatment efforts; There are various models for the treatment of abandoned open-pit mining sites, and it is necessary to choose one or more suitable combination models based on their site conditions and influencing factors, and connect them with local planning at all levels; The treatment of abandoned open-pit mining sites involves multiple treatment objectives such as mining sites, waste piles, slopes, and borrow areas. Its treatment is a complex system engineering, and various influencing factors need to be comprehensively considered before treatment to avoid blind treatment.
- 1
Design and Parameter Optimization of Prestressed Anchor rod Support for Soft Rock TunnelsAbstract:
In response to the softening of the surrounding rock along the -400 m horizontal vein roadway in the contact zone between the north and south edges of a copper mine, the failure of the original support method, and the occurrence of roadway collapse during excavation, rock mechanics tests were conducted to determine the strength of the engineering rock mass, analyze the reasons for the failure of the original support, and explore the reasonable support parameters and principles of prestressed anchor rods through numerical simulation. The control effects of different support methods on the surrounding rock were compared. On this basis, a joint support scheme with anchor spacing of 0.9 m, pre tension force of 90 kN, and sprayed concrete thickness of 100 mm was proposed. The simulation in Flac3d shows that this scheme can effectively reduce the volume of the plastic zone of the surrounding rock, and control the subsidence of the roof and the total amount of movement of the two sides of the roadway surrounding rock within 21 mm and 19 mm, respectively. Compared with no support, the reduction is 44.9% and 56.2%, respectively, and the support effect is good. The on-site application shows that this scheme can meet the needs of mine safety production, and the design and optimization of prestressed anchor support parameters for soft rock roadway based on Flac3d is reasonable and feasible.
- 1
Table1 Quantitative indicators and grading criteriaAbstract:
Green development of mineral resources has become a focus and difficulty in today"s mining industry, and backfill mining has become a widely promoted and applied technology. However, there is a lack of low-carbon evaluation system for backfill systems. In order to accurately evaluate the low-carbon performance of a mining filling system, an unascertained measure model was introduced. Ten influencing indicators were selected to construct single-indicator unascertained measure functions, and combination weights based on the measure functions for each indicator were determined. By inputting the measured values of four mining indicators into the measure functions, a single-indicator measure matrix was calculated. Then, using the weight vector, a multi-indicator comprehensive measure was computed, determining that the low-carbon grade of the full tailings paste filling system in a Shandong mine was level II, while the low-carbon grades of the coarse tailings paste filling systems in Xinjiang, Inner Mongolia, and Sichuan were level III. On this basis, using the established low-carbon evaluation model, the indicator parameters of the full tailings paste filling system in a Hunan lead-zinc mine were optimized and practically applied. The research shows that by optimizing the ratio of cementing materials to sand, increasing the diameter of the delivery pipes, enhancing the wear resistance of bends in easily worn areas, and regularly rotating the pipes, the low-carbon score can be increased from 68.23 to 81.62, an improvement of 19.6%. The evaluation grade was raised from level III to level II, providing valuable insights for the development and construction of low-carbon filling systems.
- 1
Research on the Coupling and Coordinated Development of Mineral-Economy-Mining Environment System in Resource Based CitiesAbstract:
In order to promote the high-quality development of resource-based cities, evaluation index system of mineral-economy-mine environment of resource-based cities was constructed. Comprehensive evaluation model, coupling coordination degree model, and obstacle degree model were used to analyze the comprehensive evaluation index, coupling and coordination level, and main obstacle factors of mineral-economy-mine environment system in 84 resource-based cities in China from 2020 to 2022. The results indicate that the comprehensive evaluation index of mineral resources, economy, and mine environment has all increased, but there are significant differences among resource-based cities of different types and regions. The coupling and coordination level of resource-based cities is relatively low, and the vast majority of cities are in a state of dislocation, but the overall level is increasing year by year. The main obstacle factors of the mineral system are the sales revenue of mineral products, the total output value of mining industry, and the total profit of mining enterprises; The main obstacle factors of the economic system are the total import and export trade volume, the number of patent authorizations, and the profits of industrial enterprises above a certain scale; The main obstacle factors of the mining environmental system are the area of restoration and treatment for the current year, the cumulative area of restoration and treatment and the amount of investment in restoration and treatment for the current year.
- 1
WANG Shengkai1, FANG Xugang 1, LI Huahua2, GUO Qifeng3,4, ZHOU Guanhu1, LIU Jiaming 2, XIAO Lei2, LIANG Shenlin3(1. Yunnan Chihong Zinc and Germanium Co., LTD., Qujing City 654212, China;Abstract:
The layered characteristics of rock mass in the main vein roadway of a lead-zinc mine in Yunnan with a buried depth of 1500 m are obvious, the ground pressure is severe, and the stability control is difficult. Based on the engineering geological data, the numerical model of engineering geological body is established by using 3DEC numerical simulation software. The deformation and failure characteristics of surrounding rock of roadway are compared under two working conditions of unsupported and designed support combination system after excavation of roadway with different strata dip angles, and the actual deformation monitoring of roadway is carried out. It is found that the horizontal and vertical displacements of the roadway are significantly affected by the dip angle of the rock stratum. As the dip angle of the rock stratum increases, the horizontal displacement gradually increases and the vertical displacement gradually decreases. The simulation shows that the deformation of surrounding rock decreases obviously after roadway support, and the shape of plastic zone is similar to that of unsupported roadway, but the range is small. After the support is applied, the actual roof displacement monitoring of the roadway is carried out. With the passage of time, the roof displacement gradually increases and tends to be stable after about 70 days, and the displacement of the roof gradually decreases with the increase of the dip angle of the rock stratum. The results show that the current design support system can effectively reduce the deformation of deep layered rock mass, especially the horizontal deformation of the tunnel vault and the vertical deformation of the right side, which is conducive to maintaining the long-term stability of the roadway.
- 1
Exploration of the supervision model of ecological restoration of licensed mines: a case study of Dexing CityAbstract:
With the rapid development of China‘s mining industry, it has caused a large number of geological and environmental problems in mines, such as collapse, land damage, soil erosion, etc. With the promotion of ecological civilization strategy, the demand for green development of mines is becoming increasingly high, which brings new challenges to the supervision of geological environment in mines. This article took the construction of the geological environment supervision model for certified mines in Dexing City as an example, starting from the problems existing in the current geological environment of mines. Through various data collection and analysis, combined with the dynamic detection method of drone aerial survey, field investigation, and one mine one plan, based on the results of the geological environment investigation and evaluation of mines, a new geological environment supervision model for mines is established under the new situation. Through the application of the mining geological environment supervision model, the Dexing characteristic ecological restoration models such as "ecological restoration + new energy" and "ecological restoration + cultural tourism" have been achieved, providing reference and guidance for the supervision of mining geological environment in other regions.
- 1
Rock mass quality evaluation and stability analysis of roadway support for deep scale mine weathering orebodyAbstract:
In view of the influence of weathering zone and fault cutting in the orebody area of 28-48 line in the middle 300m section of Li Lou Iron Mine, the mechanical strength is significantly reduced, the integrity is poor, and the mining technical conditions are extremely complicated. At present, the rock mass quality evaluation of four kinds of rocks in the upper and lower wall of this area is carried out, and it is concluded that the roof surrounding rock properties are poor, and the roadway outside the vein is arranged in relatively stable marble in the lower wall as far as possible. Then Flac3d was used to conduct numerical analysis on the deformation and failure characteristics of roadway surrounding rock under 4 different support types. The results show that: Compared with the case without support, the minimum principal stress of bolt + steel arch support, bolt shotcrete support, bolt shotcrete + steel arch support combined support is reduced by 1.3MPa, 5.38MPa and 5.53MPa respectively, and the maximum vertical displacement subsidence of roof is reduced by 9.91mm, 19.46mm and 20.18mm respectively. The supporting effect of roadway surrounding rock is as follows: no support < anchor rod + steel arch support < shotcrete support ≈ combined support of "shotcrete + steel arch", and the combined support scheme of "shotcrete + steel arch" has the best effect. Under comprehensive consideration, the choice of bolting and shotcrete support scheme can meet the support requirements of most of the weathering zone areas of the mine, and provide a reliable basis for subsequent roadway production and stope mining.
- 1
Practice of mining steeply inclined soft broken veins by medium-deep holes segment- open pit methodAbstract:
In order to solve the problems of poor mining safety and high loss and depletion rate of the steeple soft broken vein , the field industrial test was carried out to study the sublevel open-stope method of medium and long hole outside the vein of Shanggong Gold Mine.The results show three aspects .Firstly, all the mining works are arranged in stable rock mass outside the vein, and the safety of the construction process can be ensured by drilling medium-deep holes into the ore body from the roadway outside the vein to control and recover the ore body. In addition , The non-cutting engineering blasting trouging technology, which takes the mine approach as the initial free surface of blasting and the 3-4 rows of holes are simultaneously blasted from bottom to top to form a full section, can significantly reduce safety hazards, reduce mining costs and simplify construction technology.Lastly,the dividing line between the surrounding rock and the vein is accurately determined through the drilling process;The hole is protected by plastic sleeves and the mining is carried out by fine blasting technology. When the stope process parameters are determined as the minimum resistance line of 1.5m, the row distance of 1.5m, the hole bottom distance of 2.0m, and the single explosive consumption of 0.22kg/t, the blasting effect is the best. The loss rate is reduced to 10.1%.and the dilution rate dropped to 12.4%.
- 1
Deterioration law of mechanical properties of sandstone of cold regions under freeze-thaw and simulation analysisAbstract:
Understanding the deterioration mechanism of rockslides mechanical properties under freeze-thaw is of crucial theoretical significance for revealing and predicting frozen rockslide disasters. To accurately reproduce the deterioration process of rock mechanical properties under freeze-thaw, triaxial compression tests and numerical simulation experiments were conducted on cold-region sandstone specimens subjected to different numbers of freeze-thaw cycles, aiming to investigate the freeze-thaw degradation mechanism of rock. The results showed that with an increasing number of freeze-thaw cycles, the post-peak failure stage prolonged and a distinct yield plateau appeared. When the number of freeze-thaw cycles increased from 0 to 40, the cohesion at the peak stress decreased by 21.9%, while the internal friction angle decreased by 14.7%, indicating a significant influence of freeze-thaw cycles on the cohesive. Moreover, the elastic modulus decreased by more than 50%. Under unfrozen conditions, the peak total energy under 12 MPa confining pressure increased by 670.8% compared to that under 0 MPa confining pressure, with elastic energy increasing by 420.5% and dissipative energy increasing by 2356.6%. With 40 freeze-thaw cycles, compared to 0 MPa confining pressure, the peak total energy increased by 1030.9%, elastic energy increased by 603.9%, and dissipative energy increased by 4153.9%. The total number of cracks, tensile cracks, and shear cracks under different confining pressures all exhibited an S-shaped growth pattern with increasing axial strain, with shear cracks dominating in the early loading stage and tensile cracks appearing during the plastic stage. The research findings provide valuable guidance for understanding the deterioration mechanism of cold-region rock mechanical properties and analyzing deformation and failure.
- 1
Research on collaborative deep hole mining method of steeply inclined thin ore bodyAbstract:
Based on the safety of the national strategic mining reserve, in order to solve the problems of low mechanization level of the original mining process, large quantity of mining and cutting engineering, large labor intensity, and large dilution loss rate in the Huangsha mining area of Tieshanlong Tungsten Industry, we strived to change the drawbacks of the inherent mining process of the traditional steep thin ore body, seek a new mining process reform, and improve the mechanization degree and ore utilization rate. According to the development experience of medium diameter deep holes in similar mines, combined with the drawing process of medium and deep holes, the collaborative deep hole mining technology of up and down is realized, and the medium diameter long hole stage subsequent caving method of sharp inclined thin ore body is developed, and representative test blocks are selected for industrial tests. After a long period of industrial test and feedback optimization design, the final industrial test results show that: compared with the sublevel drilling stage caving method, the explosive unit consumption of medium diameter and long hole stage is reduced by 36%, the loss and depletion rate is reduced by 60% and 18%, respectively, and the metal recovery is increased by 18.5%. The results of industrial tests confirm the significant economic and social benefits of the mining technology of steeply inclined thin ore body, and provide a feasible scheme for deep hole blasting mining of steeply inclined thin ore body.
- 1
Performance analysis of graphite tailings improved by clay based on response surface methodologyAbstract:
In order to study the shear performance of graphite tailings storage, based on indoor direct shear tests, the effects of clay content, moisture content, quicklime content, and polypropylene fiber content on the shear performance of graphite tailings were determined through single factor experiments. The response surface methodology (RSM) was used to validate the optimal solution, and the optimal mix ratio of clay, water, and quicklime was obtained. Analyze the microscopic mechanism of action using scanning electron microscopy experiments. The results showed that with the addition of clay, water, quicklime, and polypropylene fibers, the shear strength and cohesion of the cured material first increased and then decreased, and the internal friction angle tended to stabilize. When the clay content is 29.38%, the moisture content is 15.82%, and the quicklime content is 3.59%, the optimal ratio of cohesion is 9.4173 kPa. SEM analysis shows that the improved graphite tailings particles aggregate with clay to form a cohesive structure, which enhances the shear strength of the solidified material. The boundary value of the experiment has a significant impact on the reinforcement and protection of graphite tailings pond slopes.
- 1
mud-rock flow formation in development tunnels of weakly cemented aquiferAbstract:
In order to study the mechanism of debris flow in underground development projects in weakly cemented aquifers,Taking the weakly cemented sandstone of a mine in Xinjiang as the research object, the cementation characteristics and hydraulic characteristics were analyzed. Using mathematical models of porosity, expansion rate and permeability, the permeability of the weakly cemented aquifer in the mine under different expansion rates was obtained. Based on this, the fluid-solid coupling model was used to analyze the changes in the surrounding plastic zone and seepage field during the expansion of the surrounding rock in the loose ring of the tunnel when it encountered water under the conditions of different burial depths in the development project. Research shows that: ①The expansion of surrounding rock when exposed to water will increase the water permeability of the aquifer and increase its permeability. When the expansion rate of surrounding rock increases to 30%, the unit water inflow after tunnel excavation will increase by 1.5 to 2 times, and with increasing As the development depth increases, the unit water inflow will increase significantly, providing sufficient water source for the occurrence of underground debris flows; ②The strength of weakly cemented siltstone is low, and the tunnel face of the development project is easy to form a plastic damage zone. As the depth of development increases, the plastic damage of the tunnel face becomes greater, and it is easy to collapse and decompose under the conditions of groundwater erosion and erosion. source; ③In the area where underground fissures develop, the surrounding rock has poor stability, the underground water seepage channel is clear, and the supply is sufficient. It is easy to expand, collapse and decompose under the action of groundwater, and is carried by groundwater to form debris flows. It is a key area for underground debris flows. The research results will help further reveal the formation mechanism of debris flow in underground development projects in weakly cemented aquifers.
- 1
Study on Resistance Characteristics and Erosion Wear of Coarse Aggregate Filling PipelineAbstract:
In order to solve the problem of pipe bending failure caused by erosion of tail salt particles during long distance transportation, introducing fluid mechanics theory, the calculation model of the corresponding pipeline is established, the area where the maximum erosion rate of the pipeline is located is determined. Combined with the actual mine conditions, the particle size of the tail salt is set to be 0.9~1.7mm, the particle flow rate is 0.9~1.7m/s and the curvature radius of the bend R=1.0~3.0D, the influence of particle size, velocity and curvature radius on the maximum erosion rate and the maximum erosion zone is studied. The results show that: With the increase of particle diameter, the maximum erosion zone changes from the side wall zone to the arch back zone, the turning point of erosion zone change is when the particle diameter reaches 1.3mm. The maximum erosion rate increases with the increase of particle flow velocity, when the flow velocity increases from 0.9m/s to 1.7m/s, the maximum erosion rate increases from 4.89×10-7kg/m2s-1 to 8.93×10-7kg/m2s-1, however, it has little effect on the maximum erosion zone. The curvature radius of the bend is inversely proportional to the maximum erosion rate. When the curvature radius is from R=D to R=3.0D, the maximum erosion rate decreases from 5.30×10-7kg/m2s-1 to 2.30×10-7kg/m2s-1, the maximum erosion rate can be reduced effectively and the life of the pipe can be prolonged by increasing the curvature radius of the bend properly.
- 1
Research on the Influence Law of dynamic Obstacles on Roadway Airflow based on dynamic GridAbstract:
In order to study the influence of dynamic obstacles on the wind speed of the mine, the influence of four influencing factors on the wind speed of the roadway is selected, including the wind speed of the roadway inlet, the speed of the mine car, the length of the mine car and the blocking ratio. The dynamic grid technology is used to simulate the calculation, and the variation law of the influence of different factors on the roadway airflow is obtained. The results show that the greater the difference between the inlet wind speed of the roadway and the driving speed of the mine car, the stronger the average speed change of the cross section of the roadway, and the longer the interference distance of the mine car to the airflow of the roadway, that is, the greater the influence on the stability of the mine ventilation system. The length of the mine car and the blocking ratio have little effect on the stability of the mine ventilation system.Finally,using SPSS software regression analysis, it is found that the four factors affecting the change of roadway wind speed from strong to weak are the speed of mine car, the inlet wind speed of roadway, the blocking ratio and the length of mine car, which provides a certain reference value for maintaining the stability of mine ventilation in the actual production process of coal mine.The research conclusion is of great significance to maintain the stability of mine system.
- 1
Research on Hydrogeological Conditions and Mine Pit Water Inflow of Kambove Main Mine BodyAbstract:
To accurately predict the amount of water inflow into the mine after the aquifer is exposed in the open-pit mine of the main ore body in Kambove, an on-site pumping test was conducted based on existing hydrogeological data. The pressure-to-no-pressure formula from the large well method was used to calculate mine water inflow for different mining years. The results indicate that the main ore body is divided into a strong water-rich area (I), a medium water-rich area (II), and an aquifer (III) based on on-site hydrogeological data and pumping test results. It is recommended that mining begins in the third year of production, reaching the 1300m level with a minimum underground water inflow of 15,058 m3/d. By the sixth year of production, when mining reaches the 1270m level, underground water inflow reaches a maximum of 20,236 m3/d. Considering rainfall during the rainy and heavy rain seasons, total water inflow can reach 23,152 m3/d and 46,552 m3/d, respectively. This research provides essential data to support the formulation of subsequent mine waterproofing and drainage plans.
- 1
The Impact of Resonant Leadership on Miners'Taking Charge Behavior: A Moderated Chain Mediation ModelAbstract:
Safety and stability is the premise of intelligent mine reform. In order to improve the scientific management level of coal enterprises and reduce the accident rate, based on social information processing theory self-determination theory and affective event theory, a moderated chain mediation model is constructed with taking charge behavior and harmonious safety passion as mediating variables and organizational resilience as moderating variables. The data of 364 miners from state-owned coal mines in Shanxi Province were collected in two stages by means of questionnaire survey, and the hypothesis model was verified by empirical research method. The results show that resonant leadership has a positive effect on miners' taking charge behavior; Resonant leadership positively affected miners' taking charge behavior through the independent mediating effect of perceived insider status and harmonious safety passion, and the chain mediating effect of perceived insider status and harmonious safety passion. Organizational resilience can positively regulate the relationship between harmonious safety passion and taking charge behavior, and positively regulate the chain mediation relationship between perceived insider status and harmonious safety passion.
- 1
Study on the evolution of tail wave signal in different cracking stages of supercritical CO2 fractured sandstoneAbstract:
In order to achieve accurate control of the rock breaking process, the characteristics and evolution law of the tail wave signal at different cracking stages are studied. The tail wave signal test of sandstone cracked by supercritical CO2 under triaxial confining pressure is carried out, the signal evolution characteristics and the change law of signal parameters of sandstone cracked by CO2 are analyzed, and the tail wave extension sensitive kernel function based on probability density is established. The characteristics and evolution rules of coda signals at different cracking stages are revealed. The results show that the rocks fractured by supercritical CO2 can be divided into four stages: early stage, middle stage, late stage and post-failure stage. The relative change rate of tail wave velocity shows a curve decreasing trend, which reflects the rapid accumulation process of rock sample damage. The diffusion-sensitive kernel model reveals the gradual accumulation of rock damage during the cracking process, which leads to the enhancement of internal scattering phenomenon, the intensification of energy loss and the rapid development of tail wave. The results are of great significance for the efficient and sustainable exploitation of resources.
- 1
Optimization and Application of Vertical Isolation Pillars in the Deep Mining of Gently Dipping Thick Ore BodiesAbstract:
To investigate the effect of vertical barrier pillars on the stability of surrounding rock during the deep mining of gently inclined, thick ore bodies. The objective is to optimize the design and practical application of vertical barrier pillars. A 3D detailed geological model was developed based on actual geological survey data from a deep mining project at an iron ore mine in Shandong. Numerical simulations were used to compare subsidence, stress, and plastic zone variations across four different schemes. The study identified the optimal scheme by proposing an optimization ratio per unit volume of the vertical barrier pillar. The results indicate that the position of the vertical barrier pillar is crucial for optimizing its effectiveness. In the 8# vertical exploration line, a pillar with a width of 20 meters and a thickness of 41 meters yielded the highest optimization ratios for subsidence peak, stress peak, and plastic zone volume, with values of 22.30, 2.46×10-2 and 25.52, respectively. This configuration is deemed the optimal solution. Proper reservation of vertical barrier pillars significantly enhances the stability of surrounding rock, ensuring safe and economical mining operations while potentially increasing company profits by approximately 11.20%. This research provides valuable insights for optimizing and applying vertical barrier pillar placement schemes in similar mines.
- 1
Study on mechanical properties and energy evolution characteristics of Brazilian splitting of limestone with different degrees of dissolutionAbstract:
In order to study the stress-strain relationship, mechanical parameters, failure modes, and energy changes law of limestone with different degrees of dissolution, numerical calculation models of limestone with different degrees of dissolution were reconstructed using digital image processing technology and particle flow discrete element method. A series of Brazilian splitting discrete element numerical experiments were conducted on karst limestone with different degrees of dissolution. The results show that: During the Brazilian fracturing process, limestone with different degrees of dissolution exhibits obvious multi peak characteristics and brittle failure characteristics after the peak of the stress-strain curve. When the degree of dissolution is low, the cracks generated during the failure are more evenly distributed in the limestone, and the stress transfer is also more uniform. As the degree of dissolution increases, the peak tensile strength of limestone shows an exponential decreasing trend, and the multi peak shape of the stress-strain curve becomes more obvious. The distribution of cracks in the limestone is also relatively dispersed and the S-shaped distribution is more prominent. The limestone sample shows stress concentration around the pores, making it prone to structural failure. During the failure process of karst limestone, most of the input total strain energy is first converted into elastic strain energy, and only a small portion is converted into dissipative strain energy. The increase in dissolution degree significantly reduces the total energy input and storage limit of elastic strain energy during the Brazilian splitting failure process of karst limestone, and increases the degree of strain energy dissipation.
- 1
Effect mechanism of Ca2+/Mg2+ concentration on the rheological properties of quartz-calcite slurryAbstract:
The rotary rheometer was used to study the effect of Ca2+/Mg2+ concentrations on the apparent viscosity and yield stress of single quartz/calcite slurry and mixed slurry. Combined with Zeta potential, DLVO theory, and suspension turbidity tests, the influence mechanism of Ca2+/Mg2+ concentration on surface electricity, interaction between particles, and coagulation behavior were revealed, and a theoretical relationship between micro interaction and rheological properties of slurry was established. The results indicated that an increase in Ca2+/Mg2+ concentrations could reduce the thickness of the double layer on the surface of particles, enhance the attraction between particles, promote homoaggregation of particles, and lead to an increase in the apparent viscosity and yield stress of single quartz/calcite slurry, as well as a decrease in the turbidity of suspensions. However, an increase in the concentration of Ca2+/Mg2+ could weak the attraction between quartz and calcite, weak the heterocoagulation between the two mineral particles, and lead to a decrease in the apparent viscosity and yield stress of the mixed slurry, as well as an increase in the turbidity of the suspensions. It was also found that the yield stress of the mixed slurry of quartz and calcite is logarithmically related to the Debye length of solution, and positively correlated with the square of the difference in surface potential between the two different particles.
- 1
Deformation and failure law of jointed roadway surrounding rock under dynamic loadAbstract:
The structural plane plays a controlling role in the stability of the surrounding rock of the roadway. To reveal the deformation and failure law of jointed roadway surrounding rock under the dynamic load, 3DEC software was used to simulate and analyze the influence of different burial depths, stress wave peaks, and load frequencies on the deformation and failure characteristics of jointed roadways under blasting load. The results indicate that with increasing blasting disturbance time, the displacements of the roadway roof, floor, and two sides first increased then decreased, and finally stabilized, and the deformation and failure of the roadway floor was the most serious. When the burial depth increases from 200 m to 500 m, the vertical displacement increment of the center of the roadway roof and floor, and the horizontal displacement increment of the center of the right side of the roadway reach 169.57%, 176.31%, and 109.22%, respectively; as the burial depth increases, the deformation and damage of the surrounding rock in the tunnel deepen, with the deformation and damage of the bottom rock being the most severe. When the peak stress wave increases from 4 MPa to 10 MPa, the displacement growth rates of the center of the roadway roof, the center of the roadway floor, and the center of the right side of the roadway are 47.32%, 35.44%, and 39.87%, respectively; as the peak stress increases, the plastic zone area of the surrounding rock of the tunnel also increases, and the rock mass deep in the tunnel undergoes shear failure along the joint direction. When the load frequency increases from 20 Hz to 50 Hz, the reduction rates of the maximum vertical displacement at the center of the roadway roof and floor, and the maximum horizontal displacement at the center of the right side of the roadway are 8.3%, 13.1%, and 21.2%, respectively; with the increase of load frequency, the plastic zone area around the tunnel slightly decreases. The response surface method was used to analyze the effects of burial depth, stress peak, and load frequency on the deformation of surrounding rock in tunnels. The burial depth had the most significant impact on the deformation of surrounding rock in tunnels. The research results have important scientific value in guiding mining safety production.
- 1
Effect of Particle Hydrophobicity on the Detachment Mechanism of Floatation Bubble-particle Turbulent EddyAbstract:
Particle hydrophobicity plays an indispensable role in the flotation process, but the mechanism of particle hydrophobicity on bubble-particle detachment in turbulent eddy flows remains unclear. Therefore, the detachment behavior of aggregates under different hydrophobic particles in turbulent eddy was investigated by using a self-made bubble-particle confined turbulent detachment test platform. Experimental results indicate that, the aggregates are trapped by vortex after entering the wall cavity. Two types of glass microspheres with contact angles of 64 ° and 102 ° were prepared and the stability of the aggregates can be improved by increasing the hydrophobicity of the particles. According to the action mechanism of the flow field and the movement mode of the aggregates, the bubble-particle aggregate shows two detachment mechanisms in the eddy: fluid shear and particle centrifugation. The detachment of low hydrophobic particles mainly occurs in the central region of the wall cavity, all manifested as centrifugal detachment caused by excessive centrifugal force; As the hydrophobicity of particles increases, although centrifugal detachment remains the dominant detachment mechanism, there is a 20% probability that the aggregate will undergo fluid shear detachment at the top of the wall due to strong turbulent stress.
- 1
Study on the optimization of mining effect and the migration law of ore and waste rock in gently inclined medium-thick orebodyAbstract:
In order to explore the optimization of the mining effect of the gently inclined medium-thick orebody and the study on the migration law of ore and waste rock, the gently inclined medium-thick orebody in the middle section of ? 400m to ? 360m in Caogou Mine was taken as the research background, and physical tests of three different stoping sequences were designed. The influence of mining sequence on the mining effect of orebody is studied., and the discrete element software PFC2D was used to study the migration law of ore and waste rock. The results show that : ( 1 ) The ore recovery rate of the mining sequence III is 45.56 %, the ore dilution rate is 19.29 %, and the difference of recovery and dilution is 26.27 %. Compared with the difference of recovery and dilution of the mining sequence I and the mining sequence II, the difference of recovery and dilution of stoping sequence III increased by 1.95 percentage points and 4.01 percentage points respectively. Therefore, the mining sequence III is the optimal mining scheme, that is, the upper caving orebody of the No.3 and No.2 outlets is alternately mined for three cycles, and the upper caving orebody of the No.1 outlet is continuously mined. After the No.1 outlet is mined, the upper caving orebody of the No.2 and No.3 outlets is alternately mined. ( 2 ) In the early stage of ore drawing, the displacement vector of ore and waste rock particles above and around the ore drawing port tends to the center of the ore drawing port axis. In the later stage of ore drawing, the displacement vector of ore and waste rock particles above the ore drawing port gradually tilts to the left. ( 3 ) Before the start of ore drawing and after the end of ore drawing, the contact force chain of ore and waste rock particles is in equilibrium. In the process of ore drawing, the contact force chain of ore and waste rock particles is in an unbalanced state.
- 1
Table 1 Main chemical composition of cementAbstract:
Using coal gangue and fly ash as raw materials, supplemented by Portland cement and sulfoaluminate cement as cementing materials, the composite silicates - sulfoaluminate brine peat based solid waste grouting material was prepared. The effects of the proportion of Portland cement-sulfoaluminate cement on the mechanical properties and flow properties of the grouting materials were studied. The pore size characteristics of the materials were analyzed by nuclear magnetic resonance and the hydration products were characterized by scanning electron microscopy and energy spectrum analysis. The results are as follows: (1) When the cement is 3:7, the 28d compressive and flexural strength of Portland cement is 17.05MPa and 5MPa, slump is 34.83cm, setting time is 174min, the comprehensive performance is the best; (2) The main hydration product of the slurry is C-A-S-H gel, which is mutually reinforced with the skeleton formed by gangue powder aggregate, fly ash and C-S-H gel, and is the main source of material strength; (3) The internal pore size of the material is mainly between 0~0.63μm and 1~4μm, and the pore size of 0.05~0.4μm occupies the main body.
- 1
PSO-SVM-based Prediction of Sand Release Concentration Stability and Optimisation of Relevant Parameters in Tailing Sand Storage ThickenerAbstract:
To enhance filling efficiency and achieve continuous and stable sand discharge from the tailings storage thickener, this paper establishes a sand discharge stability prediction model and optimizes parameters based on the prediction model. Considering the actual mining conditions and the results of static and dynamic flocculation sedimentation experiments, we designed and conducted orthogonal experiments. Using Particle Swarm Optimization (PSO) to optimize Support Vector Machine (SVM) regression, we developed the sand discharge stability prediction model. Based on the existing model, we established an optimization method based on a surrogate model, aiming to minimize the standard deviation of sand discharge concentration. The prediction model was updated using a hybrid point addition method, and the optimal sand discharge parameters were determined through an optimization algorithm. Taking the Dongxinzhang Iron Mine as an example, the optimal scheme for the thickener's structural parameters and sand discharge parameters was obtained and industrial tests were conducted. The results showed that the combined effects of mud layer height, sand discharge concentration, and thickening time had the greatest impact on sand discharge stability. The PSO-SVM prediction model demonstrated good accuracy in predicting sand discharge stability, with a relative error of 1.35 % in practical applications. The optimization model constructed in this paper effectively improved the stability of sand discharge concentration in the thickener, providing a theoretical basis for selecting the thickener's structural and sand discharge parameters. The optimized system is stable and reliable, with a sand discharge concentration standard deviation of 0.81 and concentration fluctuations controlled within ±1.5 %.
- 1
Study on the Performance of Sodium Salt Modified Aluminum-Based High Solid Water Material and the Adaptability of Filling Mine Abandoned RoadwayAbstract:
Aiming at many problems such as rock burst and roof management in the process of working face mining through abandoned roadway, sodium salt modified aluminum-based high solid water material was developed, which can be used for filling treatment of abandoned roadway ( goaf ) in underground mine. In order to explore the adaptability of this material in the in-situ filling treatment of abandoned roadways in mines, the advantages of this material in the treatment of abandoned roadways were analyzed by means of indoor test, numerical simulation and engineering verification, and the stress characteristics and deformation and failure laws of surrounding rock under different filling conditions were given.The research shows that: (1) The single slurry of the material is not solidified, and the mixed slurry is initially solidified within 4 ~ 15 min. The strength of the filling body can exceed 70 % of the final strength within 24 h. It has the characteristics of obvious early strength, good fluidity, high stability of filling body in closed state, and high water retention performance. (2) After filling the old roadway, the peak stress in the surrounding rock is lower than that without filling, the peak position is shifted to the shallow part, and the plastic range and the deformation of the surrounding rock are reduced. (3) The project site is filled according to the water-cement ratio of 8: 1, and the slurry transportation distance is more than 1100 m. The quick setting and early strength are obvious, and the filling rate and roof-contacted filling rate are high. Disasters such as rock burst have been effectively controlled, which proves that the material can be well adapted to the treatment of abandoned roadways in mines.
- 1
Experimental Study on Short Process Technology for Full Particle Flotation Recovery of a Eclogite type Rutile Mine in Qinghai ProvinceAbstract:
The eclogite type rutile resources in China are widely distributed and abundant in reserves.However, most of the rutile ore belongs to primary ore, with low grade, fine embedded particle size, complex ore properties, and little difference in surface properties from gangue.Bringing many challenges to mineral selection.At present, the process of rutile beneficiation is complex, with high production costs and long recovery cycles.Resulting in difficulty in effectively developing and utilizing China's rutile resources.Regarding a low-grade eclogite type rutile mine in Qinghai,We conducted experimental research on the short process technology of full particle size flotation recovery.The results indicate that:The "full particle size short process flotation recovery" process has good adaptability to this ore.By using the flotation process of "two coarse and four fine selection" to separate the screened and deslimed raw ore,Good indicators such as a yield of 3.21%, TiO2 grade of 61.70%, and recovery rate of 63.14% can be obtained, and the rutile ore has been fully recovered and utilized.This process achieves short-term recovery of rutile minerals.It can simplify the beneficiation process and save the production cost of the mine.It is also beneficial for Re selection to improve the quality of concentrate.
- 1
Research on open TBM excavation of gently inclined long inclined shaft in rich water soft rockAbstract:
The existing TBM construction tunnels are mostly surrounded by hard rock, and the open TBM construction of water rich soft rock tunnels is a global challenge. In response to the difficult geological conditions of rich water soft rock in a certain mine engineering project, numerical simulation and construction experience were used to analyze the feasibility of open TBM excavation in typical rich water fractured soft rock strata from the aspects of geological adaptability, weak fractured sandstone shoe support, and water induced softening of rich water fractured sandstone. Reasonable support measures were proposed, and the maximum roof deformation was monitored on site from 9.2cm to 4.5cm, with a controlled deformation of about 51%, effectively ensuring the safety and stability of the surrounding rock of the tunnel. At the same time, based on on-site research, the cost and duration of construction were compared, further verifying the superiority of using open TBM construction. The final construction results show that the project took 396 days to safely and successfully complete the excavation task, with a daily maximum advance of 31.53m and a monthly maximum advance of 521.53m, which is 6 months ahead of the planned construction period and has good economic and social benefits.
- 1
Experimental Study on joint prevention and control of rock burst by cutting seam and anchoring boltAbstract:
In view of the deficiency of the research on the prevention and control of rock burst in hard rock, this paper puts forward the method of joint prevention and control of rock burst by cutting seam and bolt anchoring, and prepares the bolt anchoring samples without cutting seam, the bolt anchoring samples with cutting seam and the bolt anchoring samples with cutting seam grouting, pre-tension relaxation tests and biaxial compression tests of bolts with different anchorage samples were carried out, and the strength and Factor of safety of the composite surrounding rock with slits and anchors were discussed. The results show that the stress concentration is transferred from the anchorage zone to the end of the shear seam, and the fracture evolution is transferred from the surrounding of the anchorage zone to the distal end of the shear seam, the stress concentration area is enlarged by the jointing grouting, and the key layer of flattening is formed, which extends from the anchoring area of the bolt to the end of the jointing, the fracture evolution is extended from the anchor area around the bolt to the distal end of the cut seam, which improves the overall bearing capacity of the bolt, there are three stages of decay relaxation: rapid decay relaxation, slow decay relaxation and stable decay relaxation. The relaxation process of bolt pretension can reflect the evolution of internal fracture. A simplified formula for calculating the strength of composite surrounding rock under different anchoring conditions is established, the energy consumption coefficient is defined, and a formula for calculating the Factor of safety of composite surrounding rock after excavation considering the energy consumption is derived, three methods of rock burst prevention and control are given, which can be used in engineering. The research results have good guidance and reference significance for local danger relief, anchoring, prediction and prevention and control of hard rock burst.
- 1
Experimental study of the effect of freeze-thaw action on the characteristic parameters of the acoustic emission of banded magnetite quartzitesAbstract:
In order to investigate the influence of freezing and thawing on the strength and acoustic emission characteristic parameters of the banded magnetite quartzite, mechanical and acoustic emission tests were carried out on the banded magnetite quartzite with the freezing and thawing intervals of [-20,20] ℃, and the maximum freezing and thawing cycles of 280 times. The results showed that the uniaxial compressive strength decreased from 200.93 MPa at drying to 106.64 MPa at 280 times of freezing and thawing, with a decrease of 46.93%. Before and after 70 cycles of freeze-thaw, the acoustic emission impact rate, cumulative number of impacts, count rate, cumulative counts, energy rate, and cumulative energy were significantly different in the compression-tightening stage, elastic deformation stage, and microcrack evolution stage. The main difference between high (cycles ≥ 70) and low freeze-thaw cycles (cycles ≤ 40) damage to rock samples is that high freeze-thaw cycle rock samples are prone to friction, slip, extension and other activities of their fissures under loading, which makes the rock samples always in the state of stress redistribution, which leads to a higher degree of dissipation of their energy. The cumulative number of acoustic emission impacts, ringing counts, and energy during the accelerated expansion phase of the microfracture were 47%, 42%, and 15% lower, respectively, in the rock samples after 70 freeze-thaw cycles compared to the rock samples before 70 freeze-thaw cycles. The intensity of rupture of rock samples after 70 times of freezing and thawing is obviously weaker than that before 70 times of freezing and thawing. With the increase of freezing and thawing times, the rupture characteristics of rock samples gradually transitioned from brittle to ductile rupture, and the single b-value of the rock samples showed a tendency of decreasing firstly and then increasing secondly. The deterioration of rock samples at low freeze-thaw counts is mostly due to the increase in the number and scale of their own microfractures, whereas rock samples at high freeze-thaw counts are caused by the penetration and merging between localized fracture networks.
- 1
Study on Shear Characteristics of Sandstone with Differentially Filled FracturesAbstract:
After the grouting reinforcement of fractured rock masses, both filled and unfilled cracks often coexist internally. In order to investigate the shear characteristics of rock masses under different crack filling conditions, indoor direct shear tests were conducted on intact red sandstone specimens and post-fractured grouted specimens. A numerical model of grout bonding particle flow was established to obtain the microscopic mechanical parameters of the grouted rock mass. Normal stress direct shear numerical simulations were performed on red sandstone specimens with pre-fabricated parallel 45° double cracks under different filling conditions, including unfilled, half-filled (left side filled, right side filled), and fully filled. The results show that: (1) Under the half-filled condition, tensile-shear cracks first occur at both ends of the unfilled cracks and gradually extend towards the ends of the cracks, with a larger proportion of tensile-shear cracks in the left filling condition compared to the right filling condition at this stage; (2) The number of cracks under the right filling condition is fewer than under the left filling condition, but the proportions of various cracks remain relatively constant, with the proportion of tensile-shear cracks being largest, at around 80%; (3) Under low stress, the shear strength of the right filling condition is greater than that of the left filling condition, while under high stress, the opposite is true; (4) Filling cracks with epoxy resin slurry can weaken the guiding effect of unfilled opening cracks on crack initiation and increase the shear strength of the rock mass. The research findings are of reference significance for evaluating the grouting effect on fractured rock masses.
- 1
Experimental study of simulated TBM cutter head penetration based on pre-perforated rock conditionsAbstract:
In order to explore the influence of different prefabricated perforation parameters on rock breaking by TBM cutter head, rock penetration tests were carried out on rock-like specimens with different prefabricated perforation angles, hole spacing and row spacing, and the change rules of intrusion difficulty coefficient, peak intrusion force and intrusion energy consumption after different prefabricated perforation were analyzed. The results show that the row spacing of prefabricated perforations changes from 3 cm to 5 cm, and the intrusion difficulty coefficient, peak intrusion force and intrusion energy consumption of the specimens increase gradually. As the hole spacing changes from 1 cm to 3 cm, the intrusion difficulty coefficient, peak intrusion force and intrusion energy consumption of the specimen increase gradually. When the Angle of prefabricated perforation changes from 45° to 90°, the coefficient of invasion difficulty, peak invasion force and invasion energy consumption decrease first and then increase. When the Angle is 60°, the coefficient of invasion difficulty, peak invasion force and invasion energy consumption are the least.
- 1
Study on Hole Network Parameter Optimization of Fan-Shaped Medium-Deep Hole BlastingAbstract:
After fan-shaped medium-deep hole blasting in underground metal mines, a series of problems such as roof collapse, hanging roof and high block rate are easy to occur, which have certain safety hazards and high secondary crushing cost. The hole network parameters determine the distribution of explosive energy during blasting. In order to ensure the uniformity of blasting fragmentation and the safety of blasting operation surface, it is very necessary to optimize the hole network parameters of fan-shaped medium-deep hole blasting. Aiming at the fan-shaped medium-deep hole blasting with a blast hole diameter of 89 mm in a Russian mine, the reasonable range of hole network parameters is obtained by analyzing the blasting funnel test results : the hole bottom distance is 2.8 ~ 3.2 m, and the row distance is 2.3 ~ 2.5 m. Then, the blasting models with different hole bottom distances were calculated and analyzed by ANSYS / LS-DYNA numerical simulation software, and the optimal hole bottom distance was 2.6 ~ 2.8 m. The field industrial test was carried out by using the optimized hole network parameters. The blasting fragmentation of the stope was uniform, the roof stability was good, and the overall blasting effect was good.
- 1
Study on thickness optimization of isolated pillar by caving and filling method in an iron mineAbstract:
In order to realize the smooth transition of mining by caving and filling method for a high value iron ore body, a joint mining scheme of caving and filling method is proposed from the perspective of stope stability and full recovery of high value ore body. By using simplified beam method and Rubenieit method, the thickness of isolated top column in the transition area of caving method to filling method is 10.3m and 9.4m respectively. Based on the theoretical calculation results of two kinds of isolated top pillar thickness, the numerical simulation of the combined mining scheme of an iron ore with caving method to filling method was carried out by FLAC3D software, and the thickness of the isolated top pillar in the transition area of the combined mining scheme of an iron ore with caving method to filling method was defined as 10m, and the height of the mining room with shallow hole remaining and subsequent filling method in the combined mining scheme was 14m. The application of this research to the production of an iron ore has obtained good technical and economic benefits, and provides ideas for the same type of mine caving method to filling method technology.
- 1
An Object Detection Method for Coal Gangue Flow Based on Enhanced YOLOv8sAbstract:
Coal gangue sorting is an essential process in coal mine production, and automatic identification of coal gangue is a prerequisite for intelligent sorting. Coal gangue target detection based on deep learning can fully utilize image features and has a high accuracy potential, but the models require significant computational resources, making real-time deployment challenging. To address this issue, a lightweight DVBS-YOLOv8s coal gangue target detection method is proposed. To enhance the model"s inference speed, DSConv and Vanillanet modules were introduced into the backbone of YOLOv8s, and Slim-neck was incorporated into the neck of the network to achieve lightweight design. Additionally, to improve the model"s ability to capture features of the conveyor belt background and coal gangue targets, BoT was introduced, and combined with Slim-neck, it enhanced the global feature analysis capability. Finally, WIoU and Soft-NMS algorithms were used to enhance the training effect.An image acquisition experimental platform was set up, and a dataset of 14,790 coal gangue images was self-constructed for experimentation. Results indicate that in the coal gangue target detection task, the improved model increased the receptive field and focused more on global features, while computational load decreased by 46.5% and inference speed increased by 32%. Compared to the YOLOv5 series, YOLOv7 series, SSD, Faster-RCNN, and YOLOv8s, both detection accuracy and speed were improved, providing an important reference or achieving high-precision real-time coal gangue sorting based on deep learning.
- 1
Study on the influence of axial stress under dynamic disturbance on the damage characteristics of deep roadwaysAbstract:
To study the rock explosion phenomenon induced by dynamic loads such as excavation and blasting in the deep rock roadway, the QKX-YB200 servo true three-axis rock explosion test machine is used to study the semi-circular arch-through roadway with prefabricated straight walls affected by cyclic dynamic disturbance under different axial stress, and the whole process of roadway deformation and destruction is monitored by acoustic emission technology. The results show that: (1) When the axial stress exceeds 76.5% of the peak stress of the rock roadway, a rock explosion will occur after the specimen applies cyclic dynamic disturbance. (2) The destruction mode of the rock roadway is tension-shear joint destruction, and the destruction mode of crack expansion is closely related to axial stress and dynamic disturbance. (3) The cumulative AE ring count is used to describe the degree of rock deterioration, and it is found that the degree of deterioration of the rock under dynamic disturbance is positively correlated with the initial axial static stress. The specific performance is: the greater the initial axial static stress, the higher the degree of rock degradation, the shorter the disturbance time required for rock burst, the faster the energy accumulation rate of the sample, and the more intense the rock explosion.
- 1
Optimization of energy consumption in ball mill grinding based on response surface methodologyAbstract:
In this experiment, we used the newly generated -0.074 mm particle size fraction after grinding as the evaluation criterion for energy consumption optimization, and conducted a study on the energy consumption of a certain iron ore after high-pressure roller grinding using a ZQM250 × 100 ball mill. Through response surface methodology, we investigated the effects of factors such as medium filling rate, ore feeding rate, water addition rate, and agitator speed on the energy consumption of each newly generated -0.074 mm particle size fraction, and analyzed the significance of the interaction between these factors. By comparing the results with the single factor experiment, we have reached the optimal conclusion. Research has found that in a single factor experiment, the optimal medium filling rate is 40%, the ore feeding amount is 700g, the water addition amount is 300ml (concentration of 70%), the rotational speed is 50Hz, and the energy consumption of the newly generated -0.074 mm particle size is 169.54 kWh/t. From the results of the response surface, it can be seen that the speed of the ball mill has the greatest impact on the energy consumption of the newly generated -0.074 mm particle size, followed by the medium filling rate, followed by the amount of water added, while the impact of the feed rate on the energy consumption of the newly generated -0.074 mm particle size is the smallest. Among all the factors, the interaction between medium filling rate and rotational speed is the most obvious, followed by the interaction between water addition amount and rotational speed, followed by ore feeding amount and water addition amount, then medium filling rate and ore feeding amount, followed by ore feeding amount and rotational speed, and finally the interaction between medium filling rate and water addition amount is the least obvious. The model prediction shows that the optimal experimental conditions include a filling rate of 39.71% for the medium, a feed rate of 698.15g, a water addition of 339.65ml (concentration of 67.27%), and a stirring speed of 49.73Hz. Under optimal conditions, the predicted energy consumption of the newly generated -0.074 mm particle size is 120.53 kWh/t, and the average value of the validation experiment is 118.97 kWh/t, which is very close to the predicted value. This indicates that the prediction model we obtained is reasonable and effective within the scope of this study.
- 1
Optimization of blasting parameters for medium and long holes based on rock blastability classificationAbstract:
In order to achieve the goal of reducing the cost and increasing the efficiency of the blasting operation in underground metal mines, the medium-deep hole blasting technology in the 1100m~1200m section of Taibai Gold mine is taken as the research background. The Platts coefficient, bulk density, wave impedance, integrity coefficient and tensile strength are selected as the explosiveness classification indexes of ore and rock, and reasonable weights are assigned to these 5 indexes based on the game theory combination weighting method. The maximum correlation degree between the measured values of indicators in the region to be classified and the common explosiveness classification criteria of ore and rock is calculated by the set pair analysis method. Based on this, the grade of rock explosibility in 6 exploration areas of Taibai gold deposit is determined. The original blasting parameters of the mining area were updated based on the explosiveness classification of the ore and rock, and 9 field orthogonal tests of 3 factors and 3 levels were designed in the class IV explosive zone where the blasting effect was still not ideal. According to the obtained field test results, the influence degree of each factor on the blasting effect index was analyzed, and the blasting parameters of the class IV explosive zone were optimized according to the relationship between the 3 factors and the blasting effect index. The optimal blasting parameters in the Ⅳ grade explosion zone of Taibai Gold mine are as follows: hole row spacing of 1.5m, hole bottom spacing of 2.8m and proximity coefficient of 1.8. When this parameter is applied to the actual production of Grade IV explosion area of Taibai Gold mine, the bulk rate and single explosive consumption are significantly reduced, and the amount of primary collapse is significantly increased, which realizes the cost reduction and efficiency increase of deep hole blasting process in Taibai Gold mine.
- 1
Study on the stability of unilateral exposed filling body in subsequent filling stopeAbstract:
The stability of unilateral exposed one-step filling body is the key to safe mining in the two-step mining. The stress and displacement at different positions of the one-step filling body in the 5371 stope of an iron mine were studied by means of numerical simulation and field monitoring. The results show that: ① The vertical stress of the measuring point at the bottom of the exposed filling body changes the most, about 0.48 MPa. The closer to the top of the exposed surface, the greater the horizontal displacement of the measuring point, and the maximum horizontal displacement is about 32 mm. ② The excavation rate of the two-step pillar is logarithmically related to the maximum vertical stress and maximum horizontal displacement of the exposed filling body. Different excavation times have little effect on the vertical stress at the bottom of the filling body, which is about 1.92 %. And, different excavation times have a great effect on the horizontal displacement of the top of the filling body, which is about 5.65 %. ③ The field monitoring results show that the vertical stress change in the middle of the unilateral exposed filling body is largest than that in the top measuring point during the two-step stoping, and the maximum value is 0.3 MPa. The maximum horizontal displacement occurs at the top of the filling body, reaching 30 mm, which is basically consistent with the numerical simulation results. The research results provide a guarantee for the safety of the two-step stoping of the iron mine.
- 1
Study on desulphurization and desilication of Guizhou high-sulfur and high-silicon bauxite by reverse flotationAbstract:
According to the characteristics of the ore, a new type of quaternary ammonium salt collector Y28 was used in the desilication of high sulfur and high silicon bauxite ore in Guizhou province. The content of Al2O3 is 55.69%, the content of SiO2 is 14.27%, Al/Si ratio is 3.90, the content of sulfur is 1.71%, silica-bearing minerals kaolinite and muscovite. The experiment of desulphurization and desilication was carried out by using reverse flotation process, the Al2O3 recovery is 54.07%, Al2O3 grade is 62.04%, Al/Si ratio is 6.29, sulfur content is 0.32%, it has met the requirements of the national standard four-grade bauxite.
- 1
Experimental Study on Rheological Properties of Steel Slag Unclassified Tailings Backfill Slurryxue zhenlin, 甘德清, 刘志义, 管旭
Abstract:
To investigate the rheological properties of steel slag unclassified tailings slurry under different mixing ratios, rheological tests were conducted using the controlled shear rate method. The effects of mass concentration, cement-sand ratio, and steel slag content on the rheological parameters of the slurry were analyzed, and their rheological properties were elucidated. The interaction between mass concentration, cement-sand ratio, and steel slag content on the rheological parameters of the slurry was explored using the central composite design response surface method. The results show that the influence of mass concentration on yield stress and viscosity is most significant. With the increase of mass concentration, yield stress and viscosity follow a power function growth law. The addition of steel slag reduces the viscosity and yield stress of the slurry, significantly improving its fluidity. When the steel slag content increases from 0% to 25%, the yield stress decreases by 85.43% and the viscosity decreases by 53.83%. For the interaction, the interaction between mass concentration and steel slag content on yield stress and viscosity is most significant. The increase of steel slag content promotes the degree of influence of mass concentration on rheological parameters, that is, with the increase of steel slag content, the influence of mass concentration on yield stress and viscosity gradually increases. Parameter optimization shows that when the mass concentration is 60%, the steel slag content is 30%, and the cement-sand ratio is 1:8, the yield stress and viscosity of the slurry are the lowest, and the flowability is the highest.
- 1
Study on the Adsorption Properties of Amino and Sulfhydryl Difunctional Modified Coal Gangue on Heavy Metal IonsAbstract:
The solid waste coal gangue produced in the process of coal mining and washing and the discharge of Pb(II) from industrial wastewater will bring great harm to the ecosystem and human health, and it is of great significance to study the efficient removal method of Pb(II) and the rational utilization of coal gangue for ecological and environmental protection. In this paper, a low-cost aminothiol difunctional modified coal gangue (CG-SHNH) composite was prepared by grafting (3-mercaptopropyl)trimethoxysilane (MPTMS) and 3-aminopropyltriethoxysilane (APTES) with coal gangue. The physical and chemical properties of adsorbed materials can be comprehensively analyzed by means of XRD, SEM-EDS, XFR, FTIR, BET, Zeta potential, etc. The FTIR results showed that new bands appeared at 2930 cm-1 and 2560 cm-1, corresponding to C-H and S-H tensile vibrations, respectively, and a new peak appeared at 3367 cm-1, which was the absorption peak of N-H bonds, indicating that there were abundant amino and sulfhydryl functional groups on the surface of CG-SHNH. The BET results showed that the average pore size of CG-SHNH increased significantly, from 17.33 nm to 24.54 nm. The adsorption performance of the prepared CG-SHNH on Pb(II) was studied, and the results showed that CG-SHNH had the best adsorption effect on Pb(II) with an adsorption capacity of 125 mg/g when the CG-SHNH input was 1 g/L, the adsorption time was 20 h, the temperature was 25 °C, the pH value was 6.6, and the initial concentration was 600 mg/L. The adsorption mechanism study showed that the amino and sulfhydryl bifunctional groups could synergistically promote the chelating adsorption of Pb(II), and CG-SHNH showed excellent adsorption capacity of heavy metal ions, and its adsorption performance was significantly higher than that of coal gangue and coal gangue grafted only with sulfhydryl group.
- 1
GAO Zhonghui,TENG Shouren,LI Weiwei,WANG Yuping,ZHANG Hongmei,WANG YizhuoAbstract:
In order to predict the demand for important mineral resources in Liaoning Province during the 14th Five Year Plan period，based on the development and utilization of mineral resources during the 13th Five Year Plan period, the method of demand trend analysis is adopted to track the industrial chain, collect development and utilization data of upstream and downstream production links or consumption data of downstream product end markets, and predict the actual demand and guarantee capacity of iron ore, coal, gold mine, magnesite, flux limestone, and boron ore during the 14th Five Year Plan period. The results show that the demand for iron ore ranges from 183.75 million to 191.1 million tons/a, coal from 179.92 million to 191.35 million tons/a, gold from 8.11 million to 8.92 million tons/a, magnesite from 30.48 million to 33.81 million tons/a, limestone for flux from 14.96 million to 15.4 million tons/a, and boron from 4.16 million to 5.39 million tons/a in the next 5 years. The guarantee degree of magnesite and flux limestone is relatively high, which can achieve supply-demand balance. Gold ore requires a large amount of imports, and the guarantee degree of iron ore, coal, and boron ore is insufficient. It is necessary to further strengthen the exploration of deep and peripheral mineral resources, strengthen mining capacity construction.
- 1
Remote sensing investigation and monitoring of ecological restoration of legacy abandoned mine in Northwest YunnanAbstract:
The conventional ecological restoration investigation of mines has the characteristics of high cost and difficulty in tracing the past, which has certain limitations. In order to quickly and intuitively obtain the distribution and restoration progress of abandoned mines in the region. Taking northwest Yunnan as the research area, multi-temporal remote sensing data were used to summarize the interpretation signs of abandoned mines, mine ecological restoration models and specific restoration measures in the area, and detailed interpretation and analysis were carried out. Combined with the field investigation and verification work, the distribution of historical mines in the area and the subsequent ecological restoration of mines were found out. The results show that there are 3060 historical mine spots in the area. The main types of damage are stopes and transit sites, accounting for 81.8 % of the total number of spots, and the minerals involved are mainly non-metallic minerals.In terms of mine restoration, a total of 765 restoration and management map spots were completed, with an area of about 1468 hectares. The restoration method was based on engineering restoration. The research results can provide reference for similar abandoned mine investigation and restoration management, and also provide important data support for mine ecological restoration planning, policy formulation and project work deployment arrangement.
- 1
Research on a Level Track Locking Device for Inclined Shaft Skip Hoist Runaway PreventionAbstract:
Addressing the safety and reliability issues of the car arrester brake device in the mine incline transportation system, this study introduces a novel design for a level-track lock. The research begins with a systematic analysis of the existing car arrester mechanism, followed by a detailed presentation of the new lock's design philosophy, structure, and potential failure modes. A fault tree analysis model was constructed to qualitatively and quantitatively assess the potential causes of system failure, utilizing minimal cut sets to predict the root causes of failure. Additionally, computations of probability importance and criticality importance provide quantitative measures for the significance of failure causes.The experimental results show that the newly designed flat track locking device significantly improves the braking safety and operational stability of the inclined shaft lifting container. It not only effectively improves the material transportation efficiency, but also further strengthens the reliability of the locking device with the help of fault quantification indicators.The findings contribute substantive technical support for enhancing the safety level of the incline transportation system and offer theoretical foundations for the design and optimization of related safety equipment.
- 1
Study on the Tendency of Rock Burst during Mining in a Deep MineAbstract:
Multiple mines in our country have entered the ranks of deep mining. The problem of rockburst has become increasingly prominent. Through the study of rockburst problems, the possibility and intensity of rockburst occurrence can be predicted. Taking a deep mine as the research object, based on the distribution characteristics of geostress in the mining area and rock mechanics experiments, the empirical criteria and digital simulation analysis of rockburst were used to analyze and study the rockburst. Preliminary qualitative analysis was conducted using the Barton criterion and impact energy index in empirical criteria. It was found that the rock burst tendency in the middle section above -1300m is extremely low. If it occurs, a slight rockburst will occur locally. In the middle section below 1300m, there will be slight to moderate level rockburst. By modeling and analyzing the local energy release rate index, it was found that during the mining process of the first phase (-780~-1020m) of the mine, the risk of rockburst was not high, with minor rockburst being the main type. During the second phase (-1020~-1754m) mining process, the ore body has a moderate risk of rockburst, with the potential areas for rockburst occurring at the corners of the roof, pillars, and floor of the mining area. This study has guiding significance for the next stage of construction and mining in the mine.
- 1
Sensitivity ranking theory based on CRITIC-GRA-AHP method and its application in slope stability analysisAbstract:
Abstract: Slope stability is the basis of mine safety production. It is of great theoretical and practical significance to study the sensitivity order of influencing factors of slope stability. In this paper, a sensitivity ranking theory based on CRITIC-GRA-AHP method is proposed to overcome the shortcomings of single subjective algorithm which is greatly influenced by subjectivity and single objective algorithm which has a large deviation from the actual situation on site and can only analyze specific working conditions. Taking a limestone mine in northwest Sichuan as an example, on the basis of analyzing and determining the influencing factors of slope stability such as slope height, slope angle, rock mass gravity, rock mass cohesion and internal friction angle of rock mass, the sensitivity of influencing factors of mine slope stability is analyzed by FLAC3D combined with the sensitivity ranking theory based on CRITIC-GRA-AHP combined algorithm. The results show that the sensitivity order of slope stability influencing factors under natural conditions, rainstorm conditions and earthquake conditions is as follows: (1) Under natural conditions: internal friction angle, slope height, cohesion, slope angle, gravity and bulk modulus; (2) Rainstorm conditions: internal friction angle, cohesion, slope height, gravity, slope angle, bulk modulus; (3) Under seismic conditions: internal friction angle, slope height, cohesion, slope angle, unit weight, bulk modulus. The sensitivity of influencing factors of slope stability under rainstorm conditions is stronger than that of earthquake conditions, and the sensitivity of influencing factors of slope stability under earthquake conditions is stronger than that of natural conditions. On this basis, the cloud model theory is used to optimize the overall slope angle of the slope. Finally, it is determined that the overall angle of the mine slope is 51°, which is consistent with the actual situation of the mine. The research results of this paper can provide reference for similar mine slope disaster prediction and prevention and subsequent engineering treatment.
- 1
Industrial Test and Effect Evaluation of Hydraulic Fracturing Technology of Block Caving in a Copper MineAbstract:
The efficacy of hydraulic fracturing in an refractory copper ore body was evaluated through a combination of laboratory testing, numerical simulation, and field trials. Indoor fracturing material simulation experiments were conducted on the refractory ore body. Numerical simulations were employed to investigate fracturing crack propagation under various cluster spacing, construction displacement, and scales. Surface open-hole and perforated fracturing techniques were tested and monitored on an industrial scale. The results indicate that the ore body has a favorable fracturability, possessing the potential to form multiple complex fractures. The numerical simulations suggest that a hydraulic fracturing construction displacement within the range of 4~5 m3/min and a single-stage fluid volume of 200~450 m3 are sufficient to meet the demands of fracture half-lengths of 40~70 m, resulting in complex fracture networks. Industrial trials revealed that hydraulic fractures in two wells extended shorter along the minor axis of the ore body, generally aligning with extension patterns and meeting design requirements. Compared to open-hole fracturing, perforated well fracturing, utilizing multi-cluster perforation plus temporary plugging and diversion (hole + fracture interior), produced denser hydraulic fractures, with monitored fracture lengths significantly shorter than the designed lengths. This provides a basis for the hydraulic development and fracturing induction of the natural caving method in metal mines.
- 1
Optimal Design of Pendulum Mill Inlet Air Duct Based on Coupled Simulation TechnologyAbstract:
In order to solve the problems of high energy consumption, air duct accumulation and local wear of pendulum mill, the structural design scheme of air inlet duct (including volute and air duct blade) was studied. Based on coupling simulation techniques of fluid dynamics, multiphase flow and discrete element, Numerical simulation of the internal wind field and particle field of the pendulum mill were carried out. The response surface simulation tests of volute profile, blade Angle and blade number were also performed. The results show that optimizing volute profile is beneficial to reducing pressure loss and equipment energy consumption, and reasonable selection of blade angle and blade number is beneficial to reducing the non-uniform coefficient of air duct and regulating flow field. Based on the multi-objective optimization of pressure loss and non-uniformity coefficient, the optimal scheme of air duct structure is determined as: volute 2, blade number 18, blade angle 55°. The finished product collection efficiency of the optimized scheme is 95.3%, which is 13.4% higher than that of the original scheme. The simulation results are in good agreement with the field experimental data, which can provide guidance for the optimization and energy-saving design of pendulum mill.
- 1
Study on Characteristics of Mine Water and Suitability for Resource Utilization in Ecologically Fragile Mining AreaAbstract:
To grasp the characteristics and functional utilization suitability of mine water is the premise of realizing the resource treatment and classification utilization of mine water source. Taking Yushuling coal mine as the research object, various types of mine water were collected for water samples detection, the types of mine water resource utilization were divided, and an evaluation system was established to comprehensively analyze and evaluate the functional suitability of different utilization directions of mine water. The study shows that the chemical type of mine water is mainly SO2-4·Cl--Na+ type, the membership degree of V water is 0.812-0.991, and the content of water chemical components is high. There are three potential utilization ways of drinking water, irrigation water and industrial water. The suitability evaluation results of all kinds of mine water are grade Ⅲ and Ⅳ, which are not suitable for drinking. In terms of the suitability of irrigation and industrial water, the evaluation results of different types of mine water are quite different. The gob water, fissure water SAR[3-10.8 (mmol·L-1)1/2], RSI (6.1-6.5) and other indicators show that the impact on soil physical and chemical properties is small and basically non-corrosive, suitable for irrigation and industrial water, the fire area water LSI (0.8-1.2) > 0.6, with a tendency to scale. Generally, it cannot be directly used as irrigation water, but it can be used for industrial purposes. The water quality of the warehouse water is seriously polluted. The SSP (78.4-84.5%), MHR (62.9-72.0%), RSI (7.2-7.7), LR (8.0-12.0) and other indicators show that this type of water has high harm to soil alkalinity and permeability. And it has serious corrosion and poor functional utilization potential.
- 1
The Spatial Distribution of Rock Mass in Zhong Guan Iron Mine was Constructed Based on ArcGIS SoftwareAbstract:
Obtaining the stability level of rock mass is of great significance to the deep mining of ore body, surrounding rock support and gob filling. Based on the engineering geological conditions of Zhong Guan Iron Mine, the BQ value of rock mass at the measuring point is calculated through laboratory rock mechanics basic property test, field rock mechanics test, field rock joint investigation and in-situ stress test, etc. By using the data processing and spatial analysis function of ArcGIS software, the spatial distribution pre-diction model of rock mass quality in the study area is established through Kriging interpolation technology, and the rock mass quality of -230m horizontal ore body is predicted and analyzed by using this model. Combined with the field measurement, the verification analysis shows that the predicted results are in good agreement with the actual situation, and the quality of -230m horizontal ore body in Zhong Guan Iron Mine is poor, easy to be broken and unstable. The spatial distribution prediction model of rock mass quality obtained provides a method for studying the stability level of rock mass in the case of incomplete disclosure of rock mass engineering, and provides a theoretical basis for the subsequent safe mining of Zhong Guan Iron Mine.
- 1
Research on copper ore grade classification method based on SwinV2-EfficientNetV2Abstract:
In response to the inadequacy of constructing and encapsulating long-distance feature relationships in convolutional neural networks currently utilized for copper ore grade classification, the author proposes a method that combines a SwinTransformer-EfficientNet ensemble model. This methodology fully exploits the SwinTransformer V2-t architecture's capability in summarizing long-range feature associations, as well as the EfficientNet V2-s's strength in discerning subtle local characteristics. By incorporating a linear layer to amalgamate the outputs of both models and adaptively tuning the weights of this linear layer according to the individual model's output, the mapping relationship is optimized, leading to a substantial enhancement in classification performance. Empirical validation indicates that this fused model attains an accuracy of 92.891%, precision of 93.095%, and recall of 92.654% in classification tasks. Relative to the standalone, non-integrated models, the integrated composite model exhibits an increase of 1.30% in accuracy, 1.9% and 2.186% in precision, and 0.474% and 0.237% in recall, respectively, manifesting considerable advancements.
- 1
Study on the filling effect of layered waste rock cemented backfill.Abstract:
In the filling process, layered phenomena often occur in cemented waste rock backfill, which may affect the filling effect. Therefore, it is of great significance to study the filling effect of layered backfill. In this study, the cemented waste rock backfill was sliced to analyze the aggregate distribution characteristics of different layers in the backfill. Subsequently, through numerical simulation, the influence of layered and non-layered cemented waste rock backfill on the filling effect of goaf was compared and analyzed. The study found that: (1) Non-layered backfill performs better in terms of roof support, roof subsidence, side wall stress, and internal stability, providing a more stable support effect, reducing roof subsidence, lowering side wall stress, and ensuring the safety of mining operations. (2) The stress in the middle of the roof of non-layered backfill is slightly higher than that of layered backfill, but the stress distribution on both sides of the roof is more uniform, providing a more stable roof support; the degree of roof subsidence is significantly smaller, and the support effect is better than that of layered backfill; the side wall stress is uniform with small displacement, whereas the side wall stress of layered backfill is greater with uneven displacement. (3) The presence of more fine aggregates in the upper layer of layered backfill makes it more susceptible to pressure deformation, while the uniform distribution of waste rocks in non-layered backfill provides a stronger overall load-bearing capacity with relatively small deformation. In conclusion, non-layered cemented waste rock backfill demonstrates superior support and stability in goaf, therefore, efforts should be made to control the layered phenomena in backfill composition, providing crucial support for mining operations.
- 1
Experimental study on flotation -magnetic combined technology of high oxidation rate a copper-cobalt mine in Congo（DRC）Abstract:
A copper-cobalt ore in Congo contains 2.47% Cu and 0.237% Co, which belongs to the ore with high oxidation rate and complex mineral composition. Aiming at the problems of high cost and low recovery rate of single flotation, flotation and magnetic separation combined process was used to carry out beneficiation tests according to ore properties. The results showed that easily beneficiated copper sulfide concentrate, copper oxide concentrate and cobalt concentrate could be selected by stepwise vulcanization flotation under the condition that the grinding particle size accounted for 70% of -0.074mm. The copper and cobalt minerals in the flotation tailings were recovered by strong magnetic separation, and the comprehensive copper recovery rate was 79.83% and cobalt recovery rate was 54.79%. The recovery rate of copper and cobalt was greatly improved, and the comprehensive and efficient utilization of resources was realized.
- 1
The Influence of Iron Silicon Ratio on The Dynamic Characteristics and Energy Consumption of Magnetite under Dynamic LoadingAbstract:
In order to investigate the crushing characteristics and energy conversion law of magnetite under impact load, we take magnetite with different Fe-Si ratios as the research object, and carry out impact crushing test on magnetite with different Fe-Si ratios by using Hopkinson"s compression rod to analyse the destructive deformation characteristics, compressive strength characteristics and energy conversion law of magnetite under different incident amplitudes, and combine with scanning electron microscope technology to reveal the macro-microcosmic crushing mechanism. The results show that under the impact load, the stress-strain curves of magnetite with different Fe-Si ratios do not have a compression-density phase, but directly enter the linear elasticity phase, and the modulus of elasticity and peak stress are decrease with the increase of Fe-Si ratio, and the dynamic compressive strength of magnetite decreases with the increase of Fe-Si ratio. Under the action of dynamic loading, the dissipation energy of magnetite stones with three iron-silicon ratios increases with the increase of iron-silicon ratio and incident energy, and the slopes of the fitted curves increase with the increase of iron-silicon ratio. With the increase of incident amplitude, the block size of the ore fragments is decreasing, and when the incident amplitude is the same, the block size of the ore fragments with large Fe-Si ratio is smaller than that of the fragments with small Fe-Si ratio. With the increase of the incident amplitude, the magnetite ore internal along the crystal cracks and through the crystal cracks are
- 1
Inversion analysis of surrounding rock parameters of tunnel based on LHS-WOA-ELMAbstract:
In order to improve the rationality of mechanical parameters of tunnel surrounding rock, a new inversion model of surrounding rock parameters is proposed based on a tunnel project with a super large-section in Zhuhai. After the initial samples are generated based on Latin hypercube sampling (LHS), the parameter sensitivity analysis is carried out to determine the key parameters of the surrounding rock and improve the sample structure. Then, the whale optimization algorithm (WOA) is used to optimize the number of hidden layer nodes, the initial weights and the thresholds of the extreme learning machine (ELM) to form the LHS-WOA-ELM inversion model. The inversion parameters are substituted into FLAC3D to calculate the deformation and compare with the field measured data. The results show that the parameter sensitivity analysis based on LHS can investigate the co-variation of multi-parameters with fewer samples and and determine the main parameters affecting the displacement of surrounding rock as elastic modulus E, cohesion c and internal friction angle φ. Compared with WOA, ELM and BP algorithm models, the difference between the calculated deformation values obtained by LHS-WOA-ELM inversion model and the measured deformation values is smaller, indicating that the inversion analysis method can well reflect the nonlinear and uncertain characteristics between the surrounding rock parameters and deformation, and further improve the accuracy and efficiency of the surrounding rock inversion in super-large section tunnels, which can provide a reference for determining the design parameters of underground caverns and mining projects.
- 1
Optimisation and Application of Medium and Deep Hole Blasting Parameters at Sanguikou Lead-zinc MineAbstract:
In order to solve the problems of high block rate, serious damage to the filling body and roof column on both sides during two-step mining, and large ore depletion rate, etc., which appeared when the ore block was mined back in the Sanguikou lead-zinc mine by the filling method after the rock drilling stage, the optimization of the blasting parameters was carried out, and the blasting holes with diameter of 76mm were used instead, and the theoretical calculations showed that the distance between the rows of holes was 1.8m, and the distance between the bottoms of the holes was 2.1m; or the distance between the rows of holes was 1.9m, and the distance between the bottoms of the holes was 2.0m. Compared with the original blasting parameters, the depletion rate of the on-site industrial test quarry was reduced by 19.8%, the loss rate was reduced by 4.6%, the unit consumption of explosives was reduced by 12.2%, and the block rate was reduced by 34.8%; at the same time, combined with the simulation results of the blasting effect before and after the optimization by LS-DYNA finite element software, the results show that: when using the optimized blasting parameters for blasting, the chunk rate is smaller, and the blasting effect on both sides of the hole is more effective than the original one. The block rate is smaller, and the damage to the filling body on both sides, the top pillar and the brow line of the rock-cutting roadway is smaller.
- 1
Study on static and dynamic flocculation settlement law of total tailings based on the response surface analysis methodAbstract:
Dense dewatering of tailings is a key link in the tailings filling process. In order to explore the dense dewatering performance of tailings in a mine, static and dynamic flocculation sedimentation tests of tailings were carried out on the basis of the basic physicochemical properties of tailings. A static flocculation sedimentation test was designed with the mass concentration of tailings slurry, the type of flocculant added and the amount of flocculant added as the influencing factors and the sedimentation rate as the research index. The dynamic flocculation sedimentation test with feed speed, feed mass concentration and flocculant content as influencing factors, and solid content in overflow water, underflow mass concentration and settling velocity of tailings as research indexes, and based on RSM analysis method, revealed the dynamic flocculation settlement law of total tailings under the interaction of multiple factors. The results showed as follows: 1) Through the static flocculation sedimentation test, the optimal flocculating dosage was CKFA02#, the optimal addition amount of flocculant was 20g/t, and the optimal feed concentration of tailings slurry was 10%~12.5%; 2) According to the response surface model established by dynamic flocculation settlement test, the biggest factor affecting underflow mass concentration and solid content in overflow water is slurry feeding speed, and the biggest factor affecting tailings settling speed is slurry feeding mass concentration. The interaction between slurry feeding speed and feed mass concentration has the biggest influence on underflow mass concentration. Slurry feed rate and flocculant add amount have the greatest influence on the solid content of overflow water, slurry feed rate and flocculant add amount have the greatest influence on the settling rate of tailings. 3) The optimal settlement parameters are the feed rate of tail mortar 0.55t /m2·h, feed mass concentration 11.12%, flocculant addition amount 30.0g/t. Under the optimal flocculation settlement parameters, the underflow mass concentration is 60.6%, the solid content of overflow water is 251.4mg/L, and the settlement rate of tail sand is 58.06mm/s.
- 1
Research on Collaborative Mining of High Altitude, Multiple Mineral Types, Gentle Dipping, and Multi layered Poor Mineral VeinsAbstract:
A certain gently inclined multi-layer poor ore vein is located in the mining area, which simultaneously contains lead zinc, magnet, and sulfur copper minerals. Based on the characteristics of the ore body and its low grade, a pseudo inclined strip entry filling mining method is proposed for safer and more economical mining. FLAC3D software is used to simulate and analyze the roof displacement, pillar stress, and plastic zone distribution of different entry widths. Research shows that the pseudo inclined strip entry filling mining method can effectively reduce the loss and impoverishment of ore, greatly reduce mining and cutting engineering, increase the production capacity of the mining area, and achieve separate mining and transportation of different types of minerals. It can be flexibly applied to complex and variable gently inclined ore bodies. After numerical simulation analysis, the optimal entry width for this mine is 5 m-6 m.
- 1
Study on the Evolution Characteristics of Uniaxial Compressive Deformation Field of Limestone Based on DSCM Incremental AnalysisAbstract:
The evolution and increment characteristics of uniaxial compressive deformation field of limestone sandstone based on the digital speckle correlation method (DSCM) were studied. Based on the deformation field observed by DSCM correlation method, the increment analysis method was used to calculate the increment increment of four indexes, including non-uniformity, displacement, deformation energy density and maximum shear strain under different stress increment conditions, and the evolution characteristics of the rock in the pre-peak and post-peak stages were studied. The results show that: (1) The abrupt starting stresses of non-uniformity, displacement and deformation energy density are consistent. (2) According to the incremental analysis, the energy mainly accumulates before and after the deformation localization starts, and the accumulation velocity of stress around 30 MPa increases first and then decreases, and the abrupt change amplitude of the curve is inversely proportional to the incremental step distance. (3) The evolution law of the non-uniformity index is the same with different stress increment steps, but the larger the step distance, the larger the nonlinear mutation amplitude, and the smaller the mutation starting stress. The incremental evolution of the deformation field under different increment step conditions is a nonlinear fluctuation in the early stage after the peak, and the abrupt change occurs in the vicinity of failure, and the mutation amplitude is proportional to the incremental step length.
- 1
Experimental study on flotation tailings re-separation of high oxidation rate copper-cobalt ore of SICOMINES in the Democratic Republic of the CongoAbstract:
Due to the high oxidation rate of copper-cobalt ore in SICOMINES in the Democratic Republic of the Congo (DRC), there are some copper-bearing minerals that are difficult to select, resulting in poor separation indicators. In order to recover the useful copper-containing minerals in the flotation tailings, through the analysis of the ore properties of the flotation tailings, according to the characteristics of the ore properties, the flotation tailings were subjected to gravity separation, magnetic separation, flotation and a combination of various separation methods of re-separation experimental research, and finally determined that the flotation tailings adopts a coarse and a sweep strong magnetic separation, the magnetic separation concentrate is flotated with a coarse sweep, and the flotation tailings of the magnetic separation concentrate are separated by a section of strong magnetic separation, so as to effectively recover the refractory copper-containing minerals in the flotation tailings. Compared with the original flotation process, the recovery rates of total copper and total cobalt reached 84.74% and 56.88%, an increase of 8.95 and 8.28 percentage points. At the same time, the magnetic separation concentrate of flotation tailings and magnetic separation is re-separated, which greatly reduces the leaching acid consumption of magnetic separation concentrate.
- 1
Study on the Key Influencing Factors on the Mechanical Behavior of Tailings Materials Under Freeze-Thaw Cycle ConditionsAbstract:
In order to investigate the evolution of the mechanical properties of tailings materials under freeze-thaw cycle conditions, with a view to providing a theoretical basis for the safety and stability assessment of tailings dams. Freeze-thaw cycle test and triaxial shear test were adopted as the main test methods, and the tailings specimens with different water content were subjected to 1, 3, 5, 7 and 9 freeze-thaw tests, and triaxial shear tests were carried out under the peripheral pressure conditions from 100kPa to 400kPa. The test results showed that the macrostructural deformation of the tailings increased significantly with the increase in the number of freeze-thaw cycles, especially when the water content was set at 15%, the pore structure changed significantly after seven freeze-thaw cycles, and the number of pores in the 0-250 μm3 volume class increased significantly. In addition, it was found that increasing the enclosing pressure could increase the elastic modulus of the tailings and inhibit the damage to the tailings by freeze-thaw cycling action. The deformation modulus of the tailings stabilized after five freeze-thaw cycles, while the tailings samples with high water content exhibited lower cohesion, internal friction angle and deformation modulus.
- 1
Application of Mechanized Upward Horizontal Layered Filling Method in gently inclined and thin ore bodyAbstract:
In addressing the formidable challenges posed by the mining of a gently inclined thin ore body of a fluorite mine in Guizhou, which includes arduous mining conditions, low mechanization levels, and constrained resource utilization, combined with the unique occurrence characteristics and mining technical conditions of the ore body, the mechanized upward horizontal layered filling method was proposed, this study introduced its stope structural parameters and extraction technology, a comprehensive analysis of the stope stability was conducted, utilizing the Mathews stability graph method and advanced numerical simulation software, and the results show that the stope span, the exposed area of the hanging wall and the roof are less than the theoretical limit, the settlement of the stope roof is between 0.96m~4.32mm, the maximum arch of the bottom is 3.5mm, the maximum compressive stress is 9.8MPa, the tensile stress value is far less than the tensile strength of the filling body, which stands at 0.44MPa, and the plastic zone does not form penetration. The application results of site test show that the stope production capacity is 150t/d, the stripping ratio is 12.96m/kt, the loss rate is 10%, and the dilution rate is 8%, the significant economic benefits have been achieved.
- 1
Optimization of the Mining Method Based on Game Theory-Subjective and Objective Multi-Attribute Combination WeightingAbstract:
In the optimization of mining methods, using either subjective or objective evaluation methods alone has limitations, and while combined subjective and objective evaluation methods can mitigate these drawbacks, they may face the issue of uneven weight distribution. To address this problem, an improved Analytic Hierarchy Process (AHP)-CRITIC multi-attribute combined weighting model was established, using game theory to integrate subjective and objective weights. Taking the mining method optimization in the Sijiaying mining area as an example, comprehensive evaluation and optimization were conducted for two alternative mining methods. Under the criteria of environment, economy, technology, and safety, 11 indicators closely related to mining methods were selected, and their combined weights were determined based on the game theory-subjective and objective multi-attribute combined weighting model. The study shows that, considering both subjective and objective weights through the application of game theory, the sublevel open stoping method with delayed filling has a higher comprehensive membership degree (0.711) compared to the block caving method with delayed filling, and thus it was selected as the optimal scheme. The game theory-based combined subjective and objective evaluation and optimization model provides a valuable reference for decision-making in mining method selection.
- 1
Eco-geological environment evaluation and restoration in Typical Arid Area Limestone MinesAbstract:
The Tianjing Mountain mining area is a typical limestone quarrying region for construction purposes in the arid northwest of China. Due to severe environmental damage in the mining area, natural revegetation is no longer possible, and there is an urgent need for restoration and management. In light of this, from the overall perspective of the mine's ecological and geological environmental system, research was conducted on the ecological and geological environment of the mining area using the Analytic Hierarchy Process (AHP) and Fuzzy Comprehensive Evaluation (FCE) methods. An ecological and geological environmental evaluation system was constructed that is consistent with the characteristics of typical arid areas and oriented towards mine ecology restoration. This system aims to quantitatively and accurately determine the quality levels of the ecological and geological environment of the mining area and match appropriate restoration and management models for corresponding levels. Ultimately, targeted restoration and management of the mining area were carried out using a combined model of geological disaster risk elimination, soil reconstruction, and vegetation restoration determined by the evaluation system. After long-term manual maintenance, secondary revegetation of the mine relic site was ultimately achieved. The results show that the research findings provide a relatively objective evaluation of the ecological and geological environment of limestone mines in arid regions and have good restoration and management effects. They can be replicated and promoted for application in local and similar arid and semi-arid regions for the restoration and management of mine relic sites.
- 1
Stability analysis of tailing ponds based on GEO-SLOPEAbstract:
In mining operations, tailings ponds are essential engineering structures that contain substantial quantities of tailings and waste. Therefore, ensuring their stability is crucial for operational safety and environmental protection. This study aims to validate the effectiveness of various design measures for tailings ponds to enhance their design and management. Using GEO-SLOPE numerical simulation, we conducted a comprehensive assessment of the seepage and stability of tailings ponds under different scenarios.The results demonstrate that, under a 500-year flood event, the drainage capacities of the east and west interception ditches and the overflow channels of the tailings pond comply with the required standards. Moreover, seepage analysis confirms the effectiveness of the seepage control measures implemented in the tailings dam design, particularly the use of HDPE geomembranes and the design drainage system, in providing superior seepage prevention. Furthermore, stability calculations under three different conditions indicate that the downstream slope stability of the tailings dam meets the design standards.Additionally, this study suggests the installation of manual and online monitoring facilities to enable real-time monitoring of the tailings dam body and drainage conditions, thereby mitigating the risk of unforeseen incidents. In conclusion, these findings offer valuable technical references for the future design, construction, and management of tailings ponds, thereby advancing the technology and application of tailings pond stability analysis.
- 1
Optimization Method and Sensitivity Analysis of Stope Structure Parameters Based on Response SurfaceAbstract:
In order to solve the problems such as roof instability or insufficient production capacity caused by unreasonable value of stope structure parameters. Taking an iron ore mine in Hebei Province as the background, how to adjust and obtain the ideal stope structure parameters and their sensitivity are studied. Firstly, in order to obtain the rock mass quality information, the rock mass quality survey is carried out on the northern rock mass, and the width and length of the stope are preliminarily determined by the extended Mathews stability diagram method with stable probability. Then, FLAC 3D numerical simulation is used to explore the deformation law of the maximum subsidence of stope roof with the change of structural parameters, and the prediction model of the subsidence of stope roof is built in combination with the response surface method, and the sensitivity of the factors affecting the subsidence of stope roof and its interaction relationship are proved. Finally, considering the safety and block size, the stope structure parameters of the north stope of the ore body are optimized, and the industrial test is carried out to verify the rationality of the results. The conclusions are as follows: the overall rating of the northern rock mass is grade Ⅴ and the quality is poor; The sensitivity of stope roof settlement to each parameter is as follows: stope width > stope length > stope height; The optimal stope structure parameters of the ore body are 12m wide, 36m long and 60m high, and the mined-out area contour is relatively flat and can maintain stability. The results show that the response surface method is suitable for the spatial design of underground stope, and has certain guiding significance for the adjustment of stope structural parameters in rock mass in the same area. The stability of industrial test is good, and the optimization results are reasonable. The research results can provide theoretical basis for how to adjust reasonable stope structural parameters and correctly coordinate safety and production capacity.
- 1
Efficient pseudo-dynamic method and its application into seismic stability evaluation of tailings dam in Xizang ProvinceAbstract:
An efficient pseudo-dynamic method with decoupled dangerous initial phase search strategy is proposed to enhance the computational efficiency of pseudo-dynamic method in seismic slope stability evaluation. After the efficient pseudo-dynamic method is validated, it is adopted to assess the seismic stability of high tailings dam in Xizang from the aspects of factor of safety and failure probability as well. The results of efficient pseudo-dynamic method are compared to those from traditional pseudo-static and one accounting for magnification of seismic force. The numerical results demonstrate that the factors of safety from the three methods meet the specifications in the code of safety regulations for tailings pond (GB39496-2020). The pseudo-static method with magnification of seismic force tends to provide conservative result from both aspects of factor of safety and sliding area. Negligible influences of longitudinal wave velocity on the factor of safety and failure probability are observed. As transverse wave velocity increases, the factor of safety decreases, the failure probability increases, the number of sliding surfaces arise, and the sources of seismic failure of tailings dam diversify. The output provides insight into seismic stability of tailings dam.
- 1
Numerical simulation analysis and support optimization of large section weak surrounding rock at deep phosphate mine intersectionAbstract:
By analyzing the support problem of the roof deformation at the intersection of the 1080 intake ramp 3 # of the WengFu Phosphate Mine Mill, it is concluded that the main reason for the roof deformation is that the surrounding rock is located in a relatively fractured dolomite rock layer, with poor stability, and is also affected by groundwater and severely weathered. To prevent the deformation of this area from being affected by subsequent mining operations, the original support scheme was further optimized by analyzing the failure mechanism, and a combined support method of "anchor rods, steel mesh, steel arches, and prestressed anchor cables" was adopted to support the fractured roof. Simulate and analyze the optimized support scheme using Flac3D, and conduct a 270d underground monitoring test on the optimized scheme. The monitoring test shows that the settlement displacement of the surrounding rock roof after support optimization is less than 2 mm, which is 95.35% less than the original plan's roof settlement displacement. The displacement of the two sides is less than 3mm, which is a 94.29% decrease compared to the original plan. The optimized support plan effectively controls the deformation of the surrounding rock, indicating that adding prestressed anchor cables on the basis of the original support plan has a significant improvement effect on the stability of the fractured tunnel surrounding rock.
- 1
Study on effect of ethyl oleate on reverse flotation of fine hematite and its mechanismAbstract:
Sodium oleate is one of the common anionic collectors in iron ore flotation, but due to its poor low temperature resistance and poor dispersion, the adsorption efficiency of the agent on the mineral surface is low, resulting in the increase of the dosage of the agent and the significant increase in economic cost, which has become the main problem restricting the efficient utilization of sodium oleate collector.In this paper, it is found that the addition of ethyl oleate can effectively enhance the removal effect of quartz, and reduce the amount of sodium oleate. By means of FITR, surface tension measurement and contact Angle measurement, the promoting and strengthening mechanism of ethyl oleate on quartz flotation by sodium oleate was investigated. The results showed that the adsorption strength of sodium oleate on the surface of quartz was enhanced by hydrogen bonding between ethyl oleate and sodium oleate. The actual mineral flotation research shows that compared with the single sodium oleate flotation system, the grade of sodium oleate and ethyl oleate concentrate is increased by 3.01 percentage points, and the recovery rate is increased by 3.52 percentage points.
- 1
Statistical Analysis and Causal Research of Coal Mine Accidents in China from 2021 to 2023Abstract:
In order to objectively analyze the laws and characteristics of coal mine accidents in China, using mathematical statistics, correlation analysis, cluster analysis, ABC classification, combined with origin mapping, the coal mine accidents in China from 2021 to 2023 are statistically analyzed from the aspects of accident grade, time, region and type. The results show that, the major accidents and extremely serious accidents of China's coal mine have rebounded in 2023, and prevention should be strengthened; Coal mine accidents occurred more frequently from May to September, less from November to February, and the accident rate was higher in 1-2 hours before and after the shift, which showed the characteristics of seasonality and time concentration. Coal mine accidents show obvious regional differences. Shanxi, Inner Mongolia, Shaanxi, Guizhou and Gansu are the areas with high incidence of accidents, and should be focused on prevention. The number of roof, transportation, mechanical and electrical accidents is more, and the average number of deaths caused by fire, water disaster and rock burst accidents is more, which should be classified and managed. In addition, according to the three major accident categories of roof, transportation and mechanical and electrical, the grey correlation analysis model is built to study the correlation degree of the factors causing the accident, and the accident prevention measures are put forward.
- 1
Study on ventilation network optimization of Pakrut Gold Mine based on VentsimAbstract:
Aiming at the problems faced by the underground ventilation system of Pakrut Gold Mine, such as excessive ventilation energy consumption, insufficient deep air intake, short-circuiting and circulating air flow, and irrational regulation of air flow, optimization of the shallow and deep ventilation system has become the key work of underground ventilation management. According to the current situation of underground ventilation system in Pakrut Gold Mine, we carry out mine-wide wind measurement to fully grasp the underground wind speed and wind flow distribution, analyze the ventilation capacity and wind resistance of the whole mine, and establish the theoretical model of underground ventilation and wind resistance. Using three-dimensional ventilation numerical simulation software, we establish a three-dimensional numerical model of the ventilation system of Pakrut gold mine, carry out dynamic simulation of the wind flow in the ventilation system of Pakrut gold mine, put forward optimization and adjustment plans and simulate and analyze the effect of wind regulation, so as to realize the optimization of the ventilation network. The results show that the ventilation of Pakrut mine is greatly affected by the natural wind pressure, and the natural ventilation of each line is significantly affected by seasonal changes; according to the optimization and adjustment plan of deep air distribution, most of the air flow is sent to the deep mining area through the west wind shaft, and a small part of the air flow flows to the deep ramp through the mining area, which effectively optimizes the problem of the insufficient air supply in the deep mining area. The optimized ventilation system is more stable and the airflow distribution is more reasonable, which is a good guide for the ventilation management of Pakrut Gold Mine.
- 1
Research on SSG combined support technology for disturbed surrounding rock roadway in deep well high stress miningAbstract:
It is difficult to control the creep deformation of high stress poor roadway in Jinchuan and high maintenance cost. In order to reduce the cost of roadway support, this paper proposes a combination support of “spray anchor + steel pipe beam support + anchor grouting (SSG)” through theoretical analysis, numerical calculation, and industrial test verification. Firstly, the deformation and failure characteristics of deep surrounding rock and the main influencing factors were analyzed. Then, the advantages and disadvantages of "spray anchor + U-shaped steel frame + anchor injection (SUG)" support and SSG support were compared, and the parameters of the combined support structure were determined. Finally, finite difference simulation software was used to simulate the surrounding rock of SUG and SSG supported tunnels. Results show that the maximum deformation of SUG and SSG support rocks is 38.6mm and 25.7mm respectively; and the costs of SSG support is 48% lower than SUG support within two years repair of 50m roadway. In the continuously 3-5 years deformation monitoring of the industrial experiment, for based on industrial testing of SSG support on-site, the SSG support roadway has good stability, strong security and high cost performance ratio, which meets the requirements of creep deformation control of roadway in high stress poor strata. The SSG support technology can be widely applied in the support and repair of deep unfavorable rock strata tunnels in Jinchuan Nickel Mine.
- 1
Operation and maintenance practice of Las Bambas mine digital operation center based on Internet of ThingsAbstract:
Due to the remote geographical location and harsh environmental factors of the high-altitude mine in Las Bambas, the company’s core demand for the Las Bambas mine to become an intelligent mine, and there are many concerns that are not conducive to directly deploying a large number of personnel to participate in mine operations on site. By analyzing all the functional supports in the Las Bambas mine operation value chain, after reviewing and optimizing the existing intelligent system, a solution was proposed to integrate and establish a remote digital operations center in the urban area of Lima, 588 kilometers away from the mine. The solution involved 2,599 people in the entire mine and streamlined the work process. The digital operation center achieved an efficiency of 97.7% in the integrated safety management of personnel, equipment, and environment. And made the fatigue prediction accuracy achieve 94.7%. The number of heavy trucks hitting the primary crusher structure was reduced by 90%. The role changes of 20 positions in the mine production and the on-site migration of a total of 63 employees have achieved off-site processing of process integration and on-site process scheduling, which can provide effective reference for similar mines in remote areas at high altitudes in terms of reducing personnel, off-site office scheduling, and digital operations.
- 1
Study on Benefit-sharing System for Exploitation of Resources in the International Seabed AreaAbstract:
With the development of deep-sea science and technology, the commercial development of mineral resources in the international seabed area has gradually become a reality, and the draft regulations for the development of mineral resources in the area are nearly complete, but stakeholders have yet to reach agreement on core issues such as the payment mechanism and benefit-sharing. Benefit-sharing is an important means of balancing the interests of developed and developing countries and resolving the conflicts between regional development and environmental protection, and the study of benefit-sharing is of great theoretical significance for the formation of regional development contribution systems and the improvement of development regulations. The study of benefit-sharing through literature analysis, based on the principle of "common heritage of mankind", briefly analyzes the subject and object of benefit-sharing, focuses on the key issues that need to be considered in the current benefit-sharing system, and arrives at the following conclusions: the subject of benefit-sharing is the independent state or nation, and the object is the benefits generated based on the regional resources; in the implementation of benefit-sharing regulations, there is no agreement on the contribution mechanism and the core issues, such as benefit-sharing. The following conclusions are drawn: the subject of benefit-sharing is independent countries or nations, and the object is the benefits generated based on regional resources; in implementing benefit-sharing, emphasis should be placed on the protection of the interests of developing countries, and full consideration should be given to intergenerational equity in sharing, as well as the distribution of non-monetary benefits, such as environmental benefits and scientific research benefits. Based on the above, we put forward relevant proposals for the establishment of a benefit-sharing system, with a view to achieving relative fairness and reasonableness.
- 1
Study on the corrosion characteristics and mechanical properties degradation of zinc-infiltrated anchor rod in acidic environmentAbstract:
The powder zincizing process can construct a dense and uniform zinc-iron alloy layer on the surface of the bolt to optimize the corrosion resistance of the bolt. In order to explore the corrosion resistance of zincized anchor rod in acidic environment and clarify its corrosion degradation law. The corrosion kinetics model, mechanical property degradation law and corrosion failure mechanism of ordinary and zinc-infiltrated bolts were compared and studied by carrying out bolt immersion corrosion experiments. The effects of ordinary and zinc-infiltrated bolt corrosion on the stability of roadway surrounding rock were compared and analyzed by ABAQUS numerical simulation. The engineering application of zinc-infiltrated bolts was carried out to verify the research conclusions. The results indicate that: With the increase of corrosion age, the ordinary anchor rod shows accelerated corrosion characteristics, and the zinc-infiltrated anchor rod shows uniform corrosion characteristics. After 100 days of corrosion, the yield strength of ordinary and zincized anchors decreased by 6.50 % and 2.85 % respectively, the tensile strength decreased by 6.37 % and 1.45 % respectively, and the elongation decreased by 15.85 % and 7.97 % respectively. With the development of corrosion, the tensile fracture of ordinary anchor rod changes from ductile fracture to ductile-brittle mixed fracture, and the zinc-infiltrated anchor rod still follows ductile tensile fracture. The corrosion of ordinary anchors is based on the film dissolution-failure mechanism, and the corrosion of zinc-infiltrated anchors follows the film dissolution-transformation mechanism. The zinc-iron alloy infiltration layer can effectively isolate the corrosive medium and cathodically protect the bolt matrix. After the corrosion of the bolt, the stability of the surrounding rock of the ordinary bolt support roadway is significantly higher than that of the zinc-infiltrated bolt support roadway. The displacement and stress values of the roof and two sides of the ordinary bolt support roadway increase by 50.07 %, 52.50 %, 36.85 % and 27.41 %, respectively. The displacement and stress values of the roof and two sides of the zinc-infiltrated bolt support roadway increase by 21.07 %, 22.06 %, 16.37 % and 20.54 %, respectively. This study can provide some reference for the anti-corrosion support of acid mine.
- 1
Research on Manufacturing Marine Exploration Drill bits Using 3D Printing TechnologyAbstract:
Due to factors such as high pressure, water depth, and complex geological formations, the difficulty and complexity of underwater exploration are much higher than those of land, which puts forward high requirements for the quality and performance of drill bits, and even requires customized production according to special needs. In order to provide customized drill bits in a timely manner, 3D printing technology is innovatively applied to the production process of marine exploration drill bits. Using spherical tungsten carbide (WC), cobalt (Co) powder, and diamond particles as raw materials, a method of selective laser melting technology (SLM) printing the working layer of drill bits is proposed. By testing the density and hardness of printed samples, the printing parameters were optimized. The results show that under the conditions of laser power of 400 W and scanning speed of 220 mm/s, WC-20Co diamond can achieve high-quality molding, with a maximum density of 13.45 g/cm3 and a hardness of 1455 HV; The final prepared tungsten cobalt carbide based diamond drill bit sample showed good bonding between the hard alloy and steel matrix interface. The production mode of drill bits based on 3D printing can significantly shorten manufacturing time, manufacture drill bits that are suitable for various extreme environments and complex rock layers on the seabed, and timely meet the needs of printing drill bits on ocean drilling ships.
- 1
Numerical Simulation Study on the? Extremely Thick and Hard Strata on the Abutment Pressure and Energy Evolution of StopeAbstract:
In order to reveal the evolution law and energy distribution characteristics of the influence of the movement of extremely thick and hard strata on the stope abutment pressure, through take the working face of Yang-liu Coal Mine as the research object, using numerical simulation methods to study the energy evolution process and change rule in abutment pressure. The experimental results indicate that: (1) When there is a thick and hard rock layer in the overlying rock, the advanced abutment pressure in the middle and both sides of the working face compared with the mining area without thick and hard rock layers, the advanced abutment pressure in the middle and both sides of the working face has respectively increased by about 9% and 5%. When there is a thick and hard rock layer in the overlying rock, the middle and both sides of the mining area are in a high stress state for a long time. When the mining area is disturbed by external forces, it is more likely to cause dynamic disasters such as mining tremors and ground pressure impacts; (2) When the overlying rock has extremely thick and hard strata, the change curve of stope advance abutment pressure shows a cliff type decline after its fracture. When there is no thick and hard strata in the overburden, the change curve of stope advance abutment pressure is relatively gentle compared with the former; (3) With the continuous advance of the working face distance, when there is huge thick and hard rock in the overburden, the peak value of the abutment pressure of the adjacent goaf increases by 3.6MPa and 3.39MPa respectively compared with that of the stope, and the variation law of the lateral abutment pressure of the two sides is basically the same, but the lateral abutment pressure of the roadway adjacent goaf is significantly greater than that of the roadway stope, which indicates that the existence of huge thick and hard rock makes the stress concentration, and the roadway stope will be more prone to damage; (4) The breaking of extremely thick and hard rock stratum will cause huge impact on the stope. Compared with the stope without extremely thick and hard rock stratum, its damage degree is more severe, more elastic energy is released, and the influence range is more extensive.
- 1
Slope Stability Based on Improved Cuckoo Search Optimization Algorithm And Elman Neural NetworkAbstract:
The diversity of slope structure and the fuzziness of influencing factors make the slope stability analysis show strong nonlinear characteristics. Some studies have shown that the neural network prediction model still has shortcomings such as low precision and slow convergence rate when applied to the slope stability analysis. To solve the above problems, the weight and threshold of Elman neural network are optimized by improved cuckoo search (ICS) algorithm in order to improve the convergence speed of Elman neural network and the defect that Elman neural network is easy to fall into local optimal. A slope stability analysis model based on ICS-Elman neural network is constructed. The main factors affecting the stability of the slope are height, slope Angle, pore pressure ratio, cohesion force, internal friction Angle and bulk density. 560 groups of slope data containing the above six factors are used as input vectors to predict the stability coefficient of the slope. Under the same sample data set, the results show that compared with Elman neural network and CS-Elman models, the relative error range of ICS-Elman model for the prediction of stability coefficient is -2.81%~6.98%, RMSE and MAE are 0.2750 and 0.3922, respectively,we showing better prediction effect. Compared with CPSO-BP neural network, the relative error range of ICS-Elman neural network prediction value is -1.57%~1.25%, and the prediction accuracy is better.
- 1
Design and Demonstration of Soil Sampling Sites in Areas Affected by Mining ActivitiesAbstract:
Mining activities will cause pollution to the mining area and surrounding soil. Reasonable layout of sampling sites is very important to grasp the soil environment situation and even to reverse the spatial pattern of soil pollution by remote sensing. An iron ore area and affected by mining activities in the surrounding area as sampling area, through partition control thought, the study area is divided into mining activities directly and mining activities, using the classical statistical analysis method to calculate the reasonable sampling number and layout sampling grid, based on the landscape diversity index and weighted average method, the design of soil heavy metal monitoring sampling point layout scheme. Final design: 215 sampling points are obtained by calculation of reasonable sampling number in different precision partition, Among them, the mining activity directly affected area selected 34 grids and allocated 196 sampling points through the landscape diversity index; The indirect influence area of mining activities directly uses the weighted average method, 19 sampling points are allocated through the land use type area; Through different accuracy and different methods, the distribution of woodland sampling 39, 95 farmland samples, 20 bare land samples, 16 river land sampling, 45 sampling schemes are based on remote sensing images, combined with the geographical location of the research area and the distribution characteristics of land use types, taking into account the actual sampling cost design, thus reducing the workload. However, there may be some uncertain factors in the actual sampling work, so the sampling scheme needs to be adjusted in combination with the field situation.
- 1
Study on the influence of stacked step flow on the sorting characteristics of copper mineAbstract:
In order to efficiently separate copper ore,a stacked step flow separation model was proposed based on Knelson concentrator based on centrifugal gravity separation technology combined with reverse fluidization and step flow principle,and secondary separation was realized on the basis of centrifugal separation. The pressure,tangential and axial velocity distribution law of Stacked step flow model were analyzed by using Fluent. The effects of rotational speed and reverse fluidization velocity on the separation characteristics of copper ore were studied. The results show that the pressure distribution of the flow field increases gradually from the center to the wall,but the maximum pressure of the reverse flow force does not completely fit the wall. The abrupt change of tangential velocity at the step indicates that there is a vortex,which is conducive to the separation of light particles. The axial velocity as a whole presents an upward flow,which is conducive to the discharge of light particles from the upper outlet after separation. The axial concentration distribution of Cu particles showed a decreasing trend from bottom to top, and the radial concentration was the highest near the wal,while the concentration of SiO2 particles was the highest at the top of the axial direction,and the concentration was lower at the radial direction. When the feed speed is 0.5 m/s,the rotational speed is 50 r/min,and the reverse flow velocity is 0.012 m/s,the recovery rate of Cu particles is 87.70 %,and the enrichment ratio is 13.45. The stacked step flow model has the best effect on the separation of SiO2 particles and Cu particles. The cloud image of particle volume fraction shows that Cu particles are enriched in the concave of the inner wall of the step flow,and SiO2 particles have a low volume fraction in the concave of the wall due to the separation force of vortex and reverse flow,which more directly shows the separation effect of the stacked step flow model. The research results can provide a new reference for the improvement of centrifugal beneficiation equipment.
- 1
Application of large diameter anti-slip pile in mine slope managementAbstract:
On the basis of revealing the formation mechanism and development mechanism of the slope of the submerged sliding zone in Shuguang Gold and Copper Mine, the slope treatment of the submerged sliding zone was carried out. Through on-site engineering geological survey and limit equilibrium analysis, the formation factors and process of the submerged sliding zone were studied. Based on the engineering geological survey, the formation factors of the submerged sliding zone were divided into internal and external factors, and its formation process was divided into three stages: the generation, development and penetration of slope cracks. Combined with the treatment conditions, a large-diameter anti-sliding pile treatment plan was formulated. Through engineering geological survey and parameter back calculation, the rock mass parameters and sliding surface of the submerged sliding zone were determined. According to the calculation of the residual sliding force, a single-row circular anti-sliding pile treatment plan with a diameter of 800 mm, a length of 32 meters and a hole spacing of 4 meters was constructed on the 590-meter platform. Three limit equilibrium analysis methods were used to verify the stability of the representative profile after treatment, and the results showed that the anti-sliding piles can effectively resist sliding. The research results provide a reference for mine safety production and slope treatment.
- 1
Development and Application Effect Analysis of Nano Silicon-based Micro-Foam Drilling fluidAbstract:
To address the problem of pore wall instability in the fractured formation in the geological drilling of Gansu Pingpo coal mine, the mineral compositions, microstructures and pore characteristics of mud shale formation were selected through comprehensiveSanalysis, it showed that the clay minerals mainly composed of illite and montmorillonite with high content, and the degree of mineral particle cementation was low. At the same time, the large pore and medium pore pores account for more than 80% of the total pore volume, which is easy to cause pore wall collapse under the erosion of fluid medium. Nanomaterials and microfoam agents with excellent performances were selected through laboratory experiments, nano silicon-based micro-foam drilling fluid suitable for fractured formation drilling was developed based on the low solid drilling fluid. The results showed that the drilling fluid has good fluidity and fluid loss, as well as good cementation ability. Through the field application of the new anti-sloughing drilling fluid in coal measure strata drilling, the pure drilling rate of the drilling hole was increased by 40%, the core recovery rate reached 95% and the monthly efficiency was increased by 72%, which proved that the new anti-sloughing drilling fluid has good wall protection and anti-collapse function in the fractured formation of coal measure strata.
- 1
Experimental Study on Mechanical Properties of Marble after Damage Caused by Dynamic and Static Combined loadsAbstract:
To study the mechanical properties of marble after damage caused by dynamic and static combined loads, an improved Separated Hop-kinson Pressure Bar device was utilized to conduct dynamic and static combined load damage tests at four axial compression levels (0MPa, 18MPa, 36MPa, 54MPa) and three impact velocity levels (8m/s, 9m/s, 10m/s). Subsequently, uniaxial compression acoustic emission tests were conducted on the damaged marble. The research results indicate that: (1) As the axial static pressure increases, the dynamic peak stress, dynamic elastic modulus, and wave velocity of marble all show a pattern of first increasing and then decreasing under the dynamic and static combined loads; (2) The absorption energy is closely related to the axial static pressure. When the axial static pressure level is low, the energy required for the closure of micro cracks inside the rock is mainly obtained from the impact rod. As the axial static pressure increases, the proportion of energy obtained by the rock from the impact rod gradually decreases; (3) As the increase of axial static pressure, the uniaxial compressive strength and elastic modulus of rocks exhibit a trend of first increasing and then decreasing after the dynamic and static combined loads damage. When the axial static pressure is 18MPa, the uniaxial compres-sive strength and elastic modulus of the rock reach maximum values. Appropriate axial static pressure can effectively enhance the ca-pacity of rocks to resist dynamic loads and reduce the extent of rock damage. (4) In the middle and later stages of uniaxial loading failure, the proportion of acoustic emission signals with high main frequency signals(>400kHz) is less, and the proportion of interme-diate and low main frequency acoustic emission signals (165 kHz ~ 205 kHz) is more in rocks with less damage. The proportion of acoustic emission signals from 165kHz to 205kHz shows a trend of increasing first and then decreasing during the whole loading pro-cess. The gradual decrease in the proportion of such acoustic emission signals (165 kHz ~ 205 kHz) indicating that the rock is ap-proaching failure.
- 1
Experimental Study on the Shear Strength of Granite after High Temperature and Cyclical CoolingAbstract:
In the process of exploiting geothermal resources using the EGS(Enhanced Geothermal System) method, cyclical high-temperature cooling can cause thermal damage to the reservoir rock, thereby altering the physical and mechanical properties as well as the internal microstructure of the rock. This change can result in variations in permeability, thereby affecting the efficiency of exploiting hot dry rocks. The granite samples were subjected to cyclical cooling treatments under different cooling methods after being exposed to a temperature of 400°C. Shear permeability tests were conducted on the treated granite samples under different normal stress conditions. Additionally, three-dimensional surface scanning and scanning electron microscopy experiments were employed to further investigate the effects of cyclical high-temperature cooling on the fracture surface characteristics and microstructure of the granite.The research findings indicate that both the shear strength and corresponding shear displacement of granite increase with increasing normal stress, with a more pronounced decrease in shear strength observed in the samples subjected to water cooling. Moreover, the shear strength decreases with an increase in the number of cooling cycles, and the granite samples subjected to natural cooling exhibit larger shear displacements corresponding to shear strength. The cohesion decreases with an increase in the number of cooling cycles, while there is no significant change in the internal friction angle. The initial permeability decreases with an increase in the normal stress, and the initial permeability of water-cooled samples is 1~2 orders of magnitude larger than that of naturally cooled samples. The displacement corresponding to the minimum permeability shows an increasing trend with the increase in cooling cycles, followed by a decrease, and increases with increasing normal stress. The roughness of the fracture surface(JRC) decreases with an increase in normal stress. With the increase in cooling cycles, naturally cooled samples gradually develop intergranular cracks, and the width of transgranular cracks increases. In contrast, water-cooled samples exhibit more secondary cracks and show distinct crystal fractures. These research findings are expected to provide a theoretical foundation and technical support for the exploitation of hot dry rocks.
- 1
Experimental Study of Flotation Technology for Tetrahedrite-type Copper-Silver? Polymetallic Sulfide Ore in Inner Mongolia ProvinceAbstract:
The objective of this research is to investigate a copper-silver polymetallic sulfide ore deposit in Inner Mongolia. The ore"s properties analysis reveals that, aside from minor occurrences of chalcopyrite, sphalerite, and galena, copper and silver predominantly exist in the form of chalcopyrite. Flotation test results indicate that an initial copper-silver mixed flotation process was utilized to separate copper and silver minerals from sphalerite. This was followed by regrinding and flotation of the mixed flotation concentrate, which enabled the separation of copper and silver from galena. The final process flow was established as consisting of copper-silver mixed flotation, regrinding of the mixed flotation concentrate, and copper-silver flotation selection. Closed-circuit experiments yielded a copper concentrate with a grade of 18.98% and a recovery rate of 80.98%, as well as a silver concentrate with a grade of 10521.88g/t and a recovery rate of 89.81%. The flotation tailings were channeled to subsequent lead-zinc separation operations, achieving an efficient comprehensive utilization of copper-silver mineral resources.
- 1
Correlation analysis and prediction of energy consumption of ore grinding based on blasting parametersAbstract:
To study the impact of seepage flow in the loose accumulation rock mass of the ventilation shaft in the northern sea area of Sanshan Island, Laizhou City, on the freezing temperature, a COMSOL finite element numerical model was established based on flow velocity measurements and rock material parameters. It was predicted both the intersecting time of the three-circle freezing construction of the ventilation shaft and the formation time of the freezing curtain. Furthermore, the reliability of the three-circle freezing construction scheme design and numerical simulation were verified through an engineering case. The results indicate that under the influence of high groundwater flow rates in coastal areas, the intersecting line on the upstream face during the freezing process exhibits a “serrated” pattern. Meantime, the low temperature of the freezing pipe significantly affects the downstream area due to seepage, and the freezing curtain develops asymmetrically and shifts toward the downstream seepage. In short, The three-circle freezing design leads to a relatively rapid reduction in temperature in the excavation area of the ventilation shaft. After 18 days of freezing, the temperature drops below the phase transition temperature of -1 ℃. In the validation, the intersecting time and freezing curtain formation time were25 days and 36 days, respectively. The example aligns with the numerical simulation results, and this relevant experience can serve as a reference for similar engineering projects.
- 1
Mechanical characteristics and energy evolution of hard rock damage under different upper limit stress cycle loading and unloading effectsAbstract:
Since the underground rock body is often affected by external factors, after repeated cycles of loading and unloading, resulting in changes in the local stress environment. Therefore, it is especially important to analyze the damage mechanical properties and the law of energy evolution of sandstone under different upper stress values by conducting triaxial graded cyclic loading and unloading tests on sandstone with different upper stress values. The test results show that under the condition of graded cyclic loading and unloading, the stress-strain curve of sandstone is characterized by hysteresis loops and downward bending, and the hysteresis loops are gradually enlarged with the increase of stress. Under the cyclic loading and unloading with different upper limit stresses, the axial elastic strain and axial plastic strain of sandstone showed a linear relationship with the number of cycles as the number of cycles increased, while the sudden drop of axial plastic strain indicated that the internal pore cracks of sandstone were compacted rapidly. Meanwhile, the input energy and elastic energy curves are very similar during the cycling process, showing an upward trend of nearly exponential curve. Dissipation energy grows relatively slowly in the initial cycling stage, which indicates that the original cracks in the sandstone are compressed and closed; while in the middle of the cycling, the dissipation energy shows a nearly linear growth trend, which indicates that the rock samples are in the stage of stable expansion of the cracks. The dissipation energy ratio shows a sudden decrease in the initial cycling stage; while in the mid-cycling stage, it maintains an approximate horizontal trend. In addition, under the graded cyclic loading and unloading conditions, a linear relationship between the damage variables and the number of cycles was observed for sandstones with different values of upper stress, confirming that the increment of dissipated energy under a single cyclic loading also tended to increase linearly.
- 1
Optimization Design of Support Parameters and Layout of Threaded Steel Anchor Rods for Inclined ShaftsAbstract:
To effectively ensure the long-term stability of the extension section of the auxiliary inclined shaft in a certain mine in northern Shaanxi.The influence of parameters such as thread spacing, anchorage length, and drilling diameter on the bearing performance of anchor rods was analyzed using ABAQUS software, and reasonable anchorage parameters were selected.Three types of anchor rod support schemes were simulated using FLAC3D software, and the optimal anchor rod spacing was determined through indicators such as displacement and plastic zone range. On this basis, on-site experiments and surrounding rock deformation monitoring were carried out.The research results indicate that:(1) The maximum tensile force of the anchor rod with a 10mm thread spacing and an 8mm thread spacing only differs by 7.9kN. Considering production cost factors, the anchor rod thread spacing is determined to be 10mm;(2) The maximum anchoring force of the anchor rod increases with the increase of anchoring length and drilling diameter. After exceeding the critical value, the influence of anchoring length and drilling diameter on anchoring force is relatively small. Finally, a reasonable anchoring length of 800mm and drilling diameter of 28mm are determined;(3) The control effect of anchor rod spacing support is equivalent to that of 1200mm and 1000mm. In order to improve construction efficiency, the anchor rod spacing is determined to be 1200mm;(4) On site practice has shown that after optimizing the anchoring and support parameters for surrounding rock control, the average anchoring force of the anchor rod is greater than 150kN, and the surface deformation of the surrounding rock is less than 25mm.
- 1
Optimization Study on the Design of Support Parameters for the Outer Lane of a Lead Zinc Mine VeinAbstract:
In response to the problem of excessive local support parameters and excessive support material consumption leading to longer support cycles and higher annual support costs in the support of a certain lead-zinc mine vein external roadway due to the lack of theoretical analysis, the support of the vein external roadway in the 2416 section 12-15 line area of the lead-zinc mine is taken as the engineering background. After conducting rock mass quality evaluation and measuring relevant mechanical parameters of the rock mass, the optimal support scheme is selected from the aspects of support effect and cost through numerical simulation and on-site testing methods. The results show that the combined support method of "anchor rod+steel plastic mesh+double reinforcement bar+shotcrete" can meet the stability of the roadway outside the mine vein during its service life. The length of anchor rod and anchoring agent selected is 2.4m Φ The 18mm resin anchor rod and MSCKa resin anchor agent have a spacing of 1.1m, a steel plastic grid mesh specification of 4.5m x 2.5m, a hole mesh of 6cm, a tensile strength of 60kN, a double reinforcement bar diameter of 6mm, and a sprayed concrete strength of C20. The support cost can be reduced from the original 1862.65 yuan/m to 1263.19 yuan/m, with an average cost savings of 599.46 yuan/m. The research results can provide reference and guidance for the design of underground tunnel support in similar mines.
- 1
Evaluation of the Water Gushing (Inrush) Risk and Prediction of Water Inflow in the 2-3 Coal Seam Roof of Gaotouyao Coal MineAbstract:
In order to investigate the influence of water hazards on the mining of the 2-3 coal seam roof in Gaotouyao Coal Mine, the "three maps-two predictions method" couple with GIS and AHP is used to construct a water-richness evaluation model for the 2-3 coal seam roof water-filled aquifer. Based on the comprehensive comparison of FLAC3D numerical simulation, empirical formula calculation and measured analogy, the traditional formula for calculating the development height of water flow fracture zone is modified, and the calculation results are more accurate and reliable than the previous research work. On this basis, the classification map of water inrush risk of 2-3 coal seam roof water-filled aquifer is obtained by compound superposition. Finally, the numerical method is used to predict the water inflow in Gaotouyao Coal Mine. The research shows that the water gushing risk in the central and southwestern parts of Gaotouyao Coal Mine is higher, while the water gushing risk in the northwestern and eastern parts is lower. The normal water inflow of Gaotouyao Coal Mine is 465 m3/h, and the maximum water inflow is 558 m3/h. In view of the water disaster problems faced by the mine in the future, the feasible prevention and control measures are put forward comprehensively.
- 1
Analysis of Factors Influencing Wear Risk of Filling Pipeline in Deep Mine Based on DEMATEL-ISMAbstract:
In order to better reveal the causes of wear on filling pipelines in deep mines, 12 influencing factors were identified based on literature analysis, standard method, and expert discussion method, including slurry characteristics, essential properties of pipelines, on-site installation quality of pipelines, and filling technology. By applying the DEMATEL and ISM integrated analysis method, the degree of influence and causal attribute characteristics of indicator factors are determined by processing indicator factor data. Each influencing factor is decomposed into three orders: direct, transitional, and fundamental, and a multi-layer hierarchical structure model is constructed. The results show that the DEMATEL-ISM method can comprehensively and objectively reflect the correlation of indicator factors, and the corresponding hierarchical structure can be divided into 3 layers and 4 orders. Among them, the inner diameter of the pipeline and the filling line are the fundamental causes and key influencing factors; The absolute roughness of the pipeline, the proportion of coarse particles, slurry concentration, slurry flow rate, and the corrosiveness of the filling slurry are the transition causes, while skewness rate, weighted average particle size, pipeline laying quality, aggregate shape, etc. are the direct causes. The research results can provide theoretical reference for formulating targeted measures to prevent and reduce pipeline wear and failure.
- 1
Analysis of influencing factors of horizontal well productivity in Tunlan blockAbstract:
According to the data of 7 horizontal Wells in Tunlan block, the productivity characteristics of horizontal Wells are analyzed. There are great differences in water production and productivity of horizontal Wells. Therefore, the influence of geological factors on productivity is analyzed from the aspects of coal seam depth, coal thickness, roof and floor lithology, and the influence of engineering factors on productivity is analyzed from the aspects of fracturing curve characteristics, displacement, fracturing fluid dosage and sand addition amount, as well as the influence of wellhead casing pressure, drainage continuity and water production on productivity. The analysis results show that: with well L07 as the center, the average gas production of horizontal Wells on both sides decreases first and then increases, with high water production and low gas production. However, there is a positive correlation between the average water production and average gas production on the whole, and the gas production of horizontal Wells is affected by the water production. In general, the two are positively correlated. Hydrogeological conditions affect the productivity of some horizontal Wells. The increase of seam depth, coal thickness and roof mudstone thickness is conducive to CBM extraction. The gas production of horizontal Wells with low displacement fracturing is low, and the amount of fracturing fluid and sand addition should be kept within a certain range. In the horizontal well fracturing curve, the declining and stable fracturing curves account for 81.4%, which is greatly affected by the buried depth and coal thickness, and the curves account for a large proportion of high gas production. In the process of drainage and production, long maintenance time of stuck pump, low wellhead sleeve pressure and high water production will reduce gas production. Among the above factors, gas content is the most relevant factor, and coal seam gas content is the main control factor of horizontal well productivity, which provides reference for horizontal well development in Tunlan block.
- 1
Investigation on the hard roof segmented hydraulic fracturing pressure relief roadway support technology for fully mechanized miningAbstract:
Targeting the issue of surrounding rock deformation in the 11205 working face roadway of Fujiawa Coal Mine caused by the mining-induced effect from adjacent working faces, a comprehensive analysis was conducted using theoretical analysis, numerical simulation, and field industrial testing. This study investigated the causes of mining pressure manifestations and the hydraulic fracturing-based roof cutting pressure relief mechanism. As a pre-treatment measure, hydraulic fracturing was proposed to alleviate the mining-induced stress. Field industrial tests were carried out to verify the effectiveness of the roof cutting pressure relief. The results demonstrated that hydraulic fracturing effectively weakens the strength of the hard roof and reduces mining pressure manifestations. Observations of the roof revealed that the number of cracks within the borehole walls increased significantly after fracturing, indicating a favorable fracturing effect. By setting up mining pressure monitoring points in the transportation roadway of the 11205 fully mechanized working face, field monitoring data showed that deformations of the roadway roof and two sides were reduced by 54% and 50%, respectively. Additionally, the roof stress decreased from 30 MPa to 17 MPa, confirming the effectiveness of the fracturing-induced weakening. Numerical simulation results indicated that the roof collapsed in a timely manner after fracturing, stress was released, and the stress above the coal pillar significantly decreased from the original 30 MPa to 17 MPa. The directional staged hydraulic fracturing technique effectively reduced the mining-induced stress impact on the protective coal pillar.
- 1
Study on Deep Hole Loosening and Pre splitting Blasting Technology for Hard Rock Fault in Protective Layer Working FaceAbstract:
During the mining process of the protective layer, hard rock faults, hard nodules, etc. are often encountered. This has led to difficulties in cutting, severe wear of cutting components, and reduced equipment lifespan when the coal mining machine is directly pushed for mining. The existence of hard rock faults and hard nodules seriously restricts the advancing speed of the working face. To solve the above problems, research was conducted on the soft rock protection layer working face of Ji 15-17-13070 in Pingmei Thirteenth Mine as the engineering background. The study clarified the mechanism of ultra deep hole loosening pre splitting blasting and determined the radius range of the fault hard rock fracture zone to be 0.7-1.2 meters. The influence of aperture and spacing on blasting effect was studied through numerical simulation, and it was determined that the aperture and spacing were 94 mm and 2.0 m, respectively. A technical scheme of "two lane advance drilling+ultra deep hole loosening pre splitting blasting in the working face" has been proposed and industrial experiments have been carried out to achieve parallel operation of advancement and blasting. The experimental results show that the use of this technical scheme has a significant effect on blasting pre splitting, and the fault hard rock is fully fractured. The maximum reduction in wear of the shearer's cutting teeth is 40%, and the mining speed of the working face increases by 25%.
- 1
Research on Energy Saving and Consumption Reduction of Main Ventilator with Optimized Fuzzy PID Control Based on Improved Sparrow Search AlgorithmAbstract:
In order to solve the problems of low output power due to large overshooting of the main ventilator speed by fuzzy PID control, which affects the efficiency of the motor and increases the energy consumption, we take Beixingyao mine as the research background, and theoretically analyze the main ventilator of the mine according to its characteristics, and set up the mathematical model. Combined with the main ventilator system mathematical model using particle swarm algorithm, whale algorithm and sparrow search algorithm to optimize the fuzzy PID control strategy, and in the Simulink simulation environment to build the corresponding model, to compare the experiments, through the analysis of comparisons to optimize the fuzzy PID sparrow search algorithm fuzzy PID control of the motor efficiency is relatively high, the energy consumption is relatively low, but the algorithm on the control of speed However, the control of rotational speed by this algorithm still has problems such as large fluctuation and slow response speed. Therefore, a kind of optimized fuzzy PID control using lens imaging inverse learning improved sparrow search algorithm is proposed, and the research results show that the speed overshoot of the optimized fuzzy PID control with improved sparrow search algorithm is small, and the speed of the motor can be controlled more efficiently and the energy consumption can be reduced by 16 %. The results of the study can provide a certain reference basis for energy saving and consumption reduction in the coal mining industry.
- 1
Research progress on migration and diffusion law and preventiontechnology of heavy metals in soil of metal open-pit mineAbstract:
In the process of metal open-pit mining, a large amount of solid wastes such as waste rock and tailings are discarded. Under the action of wind, rain and sunshine, heavy metals and other harmful substances in the wastes enter the soil, resulting in soil pollution inside and around the mining area, which in turn affects vegetation growth, animal habitat and human health. Therefore, it is of great significance to study the production, migration and enrichment process of heavy metal elements in open-pit mine soil to guide the prevention and control of heavy metal pollution in mines. Based on the existing research, this paper combs the influence of pollution source types, soil properties and rainwater flow on pollutant migration in open-pit mines, and summarizes the improvement measures of soil heavy metal pollution risk in mining areas, so as to provide theoretical support for soil pollution control in mining areas.
- 1
Experimental study on the ratio optimization of high concentration paste filling material based on RSMzhangpeisen, 鞠照强, 胡昕, 许大强, 肖鹏, 徐泽林, 方家鑫
Abstract:
With the purpose of improve the performance of filling materials and reduce costs, the ratio of filling materials was studied. Firstly, a four-factor and five-level test was designed based on RSM-CCD method. The response surface regression model was constructed with fly ash mass fraction A, cement mass fraction B, calcium carbonate mass fraction C and slurry mass fraction D as factors, and the slump of filling slurry, 7d and 28d uniaxial compressive strength as response values respectively. The influence of single factor and interaction on material properties was analyzed. Finally, the lowest cost ratio scheme was sought on the basis of meeting the performance requirements. The results show that : 1 ) The slump of high concentration filling slurry is only affected by linear single factor, and the interaction has no significant effect on it. The slump increases first and then decreases with the increase of A, B and C, and decreases with the increase of D. 2 ) Linearity and interaction have significant effects on the strength of high-concentration backfill at 7d and 28d. The linear change trend of high-concentration backfill strength with A, B and D does not change significantly compared with that of low concentration. With the increase of C, it decreases first and then increases. There is no significant relationship between interaction AC and backfill strength. The increase of AB and CD as one factor will promote the influence of another factor on the 28d strength, and the increase of the other interaction as one factor will inhibit the influence of another factor on the 28d strength. 3 ) The optimal proportion scheme of filling material considering cost performance is A=18%, B=10.9%, C=1.3%, D=84%, which meets the design standard of paste filling in coal mine.
- 1
Experimental study on rock burst characteristics induced by cyclic disturbance in deep tunnels under high stress conditionsAbstract:
The disturbance such as deep engineering blasting and excavation is prone to induce rockburst. To study the conditions and characteristics of rockburst induced by cyclic disturbance in deep tunnels under different stress conditions, granite specimens with semi-circular arches penetrating the tunnel were used to conduct true triaxial disturbance rockburst tests Analyzing the occurrence conditions, characteristics of rockbursts in deep engineering, the evolution process of acoustic emission, and the energy evolution characteristics inside the rock. The test results show that: (1) when the disturbance amplitude exceeds 10 MPa, rockburst occurs in the specimen. For every additional 10 MPa of disturbance amplitude, the time from the start of disturbance loading to the occurrence of rockburst in the specimen is reduced by about 30%. The greater the disturbance amplitude, the more severe the damage to the specimen, and the more shear cracks on the rock surface. (2) Cyclic disturbance significantly promotes the generation and extension of shear cracks. The disturbance not only increases the number of shear cracks but also accelerates the speed of crack propagation. (3) The accumulated elastic strain energy inside the specimen increases with the increase of disturbance amplitude. When the specimen fails, these accumulated energies are rapidly released, leading to more severe failure of the specimen.
- 1
A Biaxial Compression Test Study on the Mechanics and Failure Behavior of Shale Containing Pores under Chilled Water CirculationAbstract:
The chilled water circulation process is a key factor in natural weathering and damage. In order to explore the complex relationship between the mechanical properties and damage characteristics of bedding shale under chilled water cycling, biaxial compression tests were conducted to study the effects of bedding structure and chilled water cycling on the mechanical properties of shale containing circular pores, and the failure mode of shale was analyzed. The experimental results show that as the bedding angle increases, the strength curve of shale shows a "V" shape, and the bedding angle α=60° is lowest. After chilled water circulation, the peak strength of shale at α= 60° decreases by 38.55%. The specimens exhibit a composite failure pattern of tension and shear during failure. As the dip angle of the bedding plane increases, the failure of the specimens changes from shear cracking through the bedding plane to shear cracking along the bedding plane. The above conclusion indicates that the coupling effect of chilled water circulation and bedding angle enhances the strength and deformation anisotropy of shale.
- 1
Study on Micromechanical Properties of Waste rock-aeolian Sand Consolidated BackfillAbstract:
The particle size distribution of waste rock aggregate and the cement-sand ratio of slurry have significant effects on the mechanical properties of waste rock cemented backfill. In order to investigate the influences of these two factors on the mechanical properties of backfill, a particle flow model of waste rock cemented backfill was constructed through backfill proportioning experiments, and the evolution rules of internal cracks, force chains and particle failures in the uniaxial compression process of backfill were analyzed. The result shows that the higher the cement-sand ratio, the more sensitive the strength of waste rock cemented backfill is to the fractal dimension of aggregate particle size distribution. In cemented backfill, the interface between aggregate and cementing matrix is easy to break along the aggregate boundary and develop along the interface. The increase of fractal dimension leads to an increase in the content of fine aggregates in the sample, resulting in an increase in the proportion of shear cracks in the sample. In addition, the higher the fractal dimension, the more conducive it is to the uniform distribution of cementing matrix and its participation in bearing.
- 1
Stability analysis of panel secondary stopes mining separated by poorly backfillAbstract:
Aiming at the problems of irregular mining boundaries and poor backfill quality of primary stopes in large and thick orebodies, the regional engineering geological survey and analysis were carried out, numerical simulation was used to compare and select the proposed secondary stoping scheme, and the failure approach index (FAI) was introduced to analyze and evaluate the stability of the secondary stopes quantitatively, thus to ensure the stability of secondary stopes and the safety of the mining operation. The results show that to reduce the disturbance effect of secondary stoping on the backfill of primary stopes, the overall idea of increasing the cycle times of the stoping process and reducing the structural parameters of single stoping is reasonable, and scheme II (high-layer cut-and-fill stoping method) has the best control effect on deformation and plastic failure of the stope roof and primary poor backfill. Most of the secondary stoping area belongs to the low-disturbance or damage zone (i.e., FAI < 2.0), and the maximum depth of the local failure zone on the side wall of stopes is 2.23m. The overall stability of the secondary stopes is good under the mining disturbance in Scheme II. The research results can provide a necessary basis and reference for safety stope under similar conditions.
- 1
Analysis of fluid-structure coupling creep characteristics of red layer soft rock eroded by acid solutionAbstract:
In order to investigate the mechanism of damage and deterioration and landslide instability of weathered red layer soft rock under acid rain, the coupled stress-seepage creep experiment of red layer soft rock under repeated erosion by acid solution was carried out to analyze the coupled creep mechanical behavior of rock and the damage evolution mechanism. By analyzing the creep time-strain curve of rock under different experimental conditions and the relationship between creep rate and permeability of rock before and after hydrochemical damage, the damage and degradation mechanism of rock under the coupled action of chemistry-stress-seepage and the main factors affecting rock damage are explored. The experimental results show that the triaxial strength of rock can be reduced by hydrochemical action, with the lowest reduction range being 36.31% and the highest 48.03%. At the same time, the divergence of rock creep curve after repeated hydrochemical erosion is stronger. There is a good positive correlation between rock damage law and stress level under different hydraulic conditions, and the damage degree of water chemical damage is much higher than the damage degree of seepage and stress, which will aggravate the deterioration damage of rock after water chemical damage. Under the action of high osmotic pressure, the pressure dissolution effect of rock is stronger, making the creep effect more obvious. At the same time, chemical damage factors are introduced to establish a three-axis nonlinear damage creep model under the coupled action of stress-seepage including chemical damage, so as to explore the damage and failure mechanism of the coupled chemistry-stress-seepage rock, and provide a theoretical reference for disaster prevention and control.
- 1
Study on the effect of paddle composite structure on the homogeneity of filling slurryAbstract:
In the pursuit of achieving optimal homogenization of slurry for mine filling applications, the present study endeavors to establish a turbine mixer model employing SolidWorks three-dimensional modeling software. The investigation delves into the ramifications of varied paddle configurations on the uniformity of the filling slurry via computational fluid dynamics simulations facilitated by Fluent software. A comprehensive examination of the stirring mechanisms induced by diverse paddle structures is undertaken, aiming to illuminate the dynamic motion states and distribution patterns of the slurry in response to differential paddle-induced perturbations. The empirical findings gleaned from this inquiry posit that the utilization of single blades featuring diverse angles within the mixing drum elicits distinct vortex formations, thereby instigating the requisite perturbation conducive to slurry homogenization. Comparative scrutiny reveals the 60° blade configuration to manifest a discernibly superior equilibrium between radial blending and axial conveying capabilities vis-à-vis the 45° and 90° counterparts. Furthermore, the innovative integration of combined mixing blades characterized by upper and lower slanted 60° blades oriented in opposing directions engenders a distinctive dual-vortex mode, thereby substantially augmenting shear forces and axial conveying capacities. This amplification in stirring efficacy, relative to the singular 60° blade configuration, markedly expedites the homogenization process of the slurry.
- 1
Point load strength test and prediction of tensile and compressive strength of irregular rock samples in deep mineAbstract:
Due to the high degree of development of joints and fissures in deep high in-situ stress mines and the frequent occurrence of core disking in boreholes, the quality and the degree of integrity of the rock mass is poor, leading to the difficulty in intact core sampling on the site. In this paper, irregular rock samples from the main ramp of Jinchuan No. 2 Mine 610m could select to conduct point load tests to obtain point load strength for different lithology. The test results showed that: the modified point load strength Is(50) of the irregular rock sample follows the normal distribution. By comparing the standard deviation ? and the coefficient of variation ? of the test data under different calculation methods and correction methods. It is determined that the point load strength of amphibolite could calculate by the equivalent diameter (linear correction) method, and the point load strength of granite could calculate by the loading spacing method. The point load strength Is of irregular rock samples shows the obvious power function relationship with the shape factor ? and the loading spacing D. The relative deviation of Is of ?≤20% is used as the sample selection criterion to determine the range of values of amphibolite and granite ? and D. The relationship between the modified point load strength ?Is(50) and the tensile and compressive strength ?t and ?UCS for irregular rock samples is established, which can quickly estimate the strength of the surrounding rock and provide the important basis for rock mass quality classification and the tunnel support plan determination.
- 1
Visualization and Feature Enhancement Study on Rockburst Risk in Phosphorus Ore TunnelsAbstract:
The visualization of rockburst risk is of paramount importance for the exploitation of deep phosphate mineral resources. Firstly, aluminum metal uniaxial loading experiments demonstrate that temperature variations due to thermo-mechanical coupling can be detected by the MicroIIIS series 640 type infrared thermography, and stress amplification is identified as the primary cause of elevated temperatures resulting from thermo-mechanical coupling. Subsequently, addressing the issues of blurred infrared images and irrelevant high-temperature bodies in actual phosphate mine tunnels interfering with the effective infrared radiation characteristics, an adaptive grayscale stretching algorithm is employed to enhance the original grayscale images, optimizing information entropy, histogram equalization, and global contrast. Moreover, a non-linear mapping pseudocolor transformation based on temperature width adjustment is applied to enhance the visualization detection of rockburst risk in actual phosphate mine tunnels. Finally, field tests in phosphate mine tunnels confirm that the DMYB-03 handheld rockburst detector, after infrared image enhancement, not only provides clearer displays of details within the tunnels and the infrared radiation characteristics caused by stress concentration but also categorizes stress concentration levels into stable, moderate, and high categories based on color brightness indicators for risk and safety areas. The images with high stress concentration exhibit a 26.55% higher information entropy, a 25.08% higher mean brightness, an 8.36% higher brightness histogram equalization, a 2.34 times higher global contrast, semi-quantitatively reflecting the degree of stress concentration in rock masses, thereby providing technical support for the visualization detection of rockburst risk in fields such as mining and transportation.
- 1
Stress-structural failure of deep crushing station right section in Jinchuan mine:A numerical simulationAbstract:
In order to address the potential stress-structural failure problem resulting from the excavation of the right section in the deep crushing station, an unmanned aerial vehicle (UAV) is utilized to collect geological conditions and rock mass data of the working face. From this data, crucial geometric information such as the attitude and spacing of rock structure planes is extracted. Using the identified attitude and spacing data, a three-dimensional rock numerical calculation model of the right section in the deep crushing station is constructed using discrete element methods (3DEC). The research findings indicate that the instability of the surrounding rock in the right section is influenced by both the stress field in the contact area between the red-brown granite strata and the gray-black gneiss strata. The primary cause of stress-structural failure is the formation of unfavorable blocks between JSet #2 and JSet #3 joint sets and the excavation free face due to unloading caused by the crushing station excavation. Consequently, one of the critical concerns for ensuring the stability of the surrounding rock during the excavation of the crushing station lies in the stress-structural failure disasters in the sections with developed joints. It is recommended to adopt an approach that combines "optimized excavation parameters + integrated support forms" to systematically control stress-structural failure at three levels: surface, shallow, and deep, subsequently to unloading caused by the excavation of the crushing station.
- 1
Experimental Study on Recovering Copper from Magnetic Separation Tailings of an Iron OreAbstract:
To efficiently recover copper from magnetic separation tailings of an iron mine in Anhui, the occurrence states of copper, zinc, and sulfur minerals were investigated, and the key process conditions affecting copper recovery were optimized through flotation experiments. The results showed that copper (0.10%) mainly occurred as chalcopyrite, zinc (0.37%) mainly occurred as sphalerite, and sulfur (3.22%) mainly occurred as pyrite in the magnetic separation tailings, with all minerals exhibiting fine-grained dissemination. Employing a mixed flotation-preferential copper flotation process, the optimal reagent combination was determined: collector PQ-5 dosage of 70 g/t; sphalerite depressant as a combination of 400 g/t sodium sulfide, 500 g/t zinc sulfate, and 400 g/t sodium sulfite; pyrite depressant PZ-1 dosage of 300 g/t. The closed-circuit test adopted a one roughing, three cleaning, and two scavenging process, ultimately obtaining a copper concentrate with a grade of 20.85% and a recovery of 81.41%. Meanwhile, the removal rates of zinc and sulfur in the concentrate reached 94.12% and 96.30%, respectively, achieving effective separation of copper from other minerals. The research results can provide valuable reference for the efficient recovery of copper from the magnetic separation tailings of this iron mine.
- 1
Risk identification of goaf multi-source index based on optimized extreme learning machine modelAbstract:
In order to improve the prediction accuracy of multi-source index risk identification in goaf, a PSO-ELM method was proposed to optimize the input weight and threshold of extreme learning machine (ELM) based on particle swarm optimization (PSO) algorithm. Nine indicators, including mining depth, mining method, goaf height, maximum exposed area, maximum exposed height, maximum exposed span, mining pillars, measured volume, and control rate, were used as the main input values to predict the risk level of a certain mine in South China's goaf. 135 measured goaf data were used as an example. The research results show that the prediction accuracy of radial basis functions and traditional extreme learning machines is 88% and 92%, respectively, while the prediction accuracy of the extreme learning machine model optimized by particle swarm optimization algorithm is 96%. Compared with radial basis functions and traditional extreme learning machines, the PSO-ELM algorithm performs better on the test set, has better stability and generalization ability, has good guiding significance and practicality, and is suitable for practical engineering applications.
- 1
Optimization of section shape of brittle direct roof roadway in western Hubei phosphate mine based on rock burst prevention and controlAbstract:
Rock burst is the main technical challenge that troubles the safe mining of phosphate mines in the western Hubei region. Some mines have a certain thickness of brittle direct roof, which leads to frequent rock burst disasters at the top of their tunnels. In order to reduce the risk of brittle direct roof rockburst in western Hubei phosphate mines, the study focuses on the+80m working face of Shaiqihe phosphate mine, analyzes the applicability of different tunnel section shapes in brittle direct roof mines, and proposes an inverted trapezoidal section scheme that is conducive to rockburst prevention and control; Using numerical simulation methods to study the distribution characteristics of stress, elastic energy, and displacement of surrounding rock under different cross-sectional shapes, selecting the optimal cross-sectional shape, and optimizing the design of relatively safe and economical cross-sectional parameters. Finally, engineering verification is carried out on the working face site. The results show that for brittle direct roof mines, the stress concentration on the rectangular section roof is most significant; The span of the inverted trapezoidal section roof is relatively large, resulting in significant direct roof settlement. However, the stress distribution of the inverted trapezoidal section roof is relatively uniform, and the stress and elastic energy of the roof are significantly released. From the perspective of reducing rock burst risk, the inverted trapezoidal section is the optimal section shape; The corresponding optimal cross-sectional parameters are 3.4 meters for the upper bottom, 3 meters for the lower bottom, and 4 meters for the height; After optimizing the cross-section of the roadway, the phenomenon of direct roof rock burst on the working face has been significantly reduced. The research results can provide reference for the design of similar mine cross-sections in the western Hubei region. Key words: Phosphate rock; Brittle roof; Rock burst; Section optimization; Numerical simulation
- 1
Optimization of filling mining scheme and stope structure parameters in an iron ore depositAbstract:
In order to optimize the filling mining scheme and stope structural parameters of a high value iron ore deposit, the mining scheme optimization is regarded as a typical fuzzy decision-making problem in combination with the mining technical conditions of -120m~-180m stage of the deposit. Using the weight of 11 indexes obtained by analytic hierarchy process and fuzzy mathematics, the mining scheme of an iron ore mine is selected as the open stope and subsequent filling method. Four kinds of stope structural parameters of the preferred mining scheme were optimized based on numerical simulation. The simulation results show that: In the process of returning to the mining room, the tensile failure of each scheme is obvious, and the stress concentration occurs at the junction of pillar and roof. The maximum horizontal displacement and maximum vertical displacement of the central monitoring point of the two sides of the stope in scheme II are small, which are 9.4mm and 7.3mm respectively. In the process of mining pillar, the shear failure of each scheme is obvious, and the maximum vertical displacement of stope roof center of scheme II is the smallest, which is 28.0mm. From the perspective of safety and economy, the optimal stope structure parameters of an iron mine are scheme II: room width 15m, pillar width 15m. The scheme and the optimized stope structure parameters have obtained good economic benefits in mine production.
- 1
Hyperspectral inversion study of soil heavy metal content in the Pb-Zn mining catchment areaAbstract:
The serious problem of heavy metal compound pollution existing in the lead-zinc mining area, using hyperspectral remote sensing technology to extract the heavy metal absorption characteristic wave spectrum in the soil, to realize the rapid monitoring of the heavy metal pollution of the mining area. We collected 100 soil samples in the field taking Gangdese Lane multi-lead-zinc ore collection area in Tibet as an example. The content analysis and hyperspectral data determination of the sample were carried out in the laboratory. Then the spectral data were subjected to the spectral transformations of first derivative (FD), second derivative (SD), reciprocal logarithmic transformation(AT), first derivative of , reciprocal logarithmic (AFD), second derivative of , reciprocal logarithmic (ASD), to analyze the correlation between the measured content of Cd, Pb, As and Hg and the soil spectra. After selecting the corresponding characteristic bands, we established four inversion models based on the characteristic bands, namely, multiple stepwise regression (SMLR), support vector machine (SVM), artificial neural network (ANN), and random forest (RF) combined with the coefficient of determination (R2) and the root-mean-square error (RMSE) to evaluate the model accuracy. Then the best combination of spectral transformation and inversion model were explored. The results show that: (1) the data dimensionality reduction effect of different spectral transformations is different from the screening interval of the characteristic bands, and Among the five transformations, AT, SD and ASD screening were better than FD and AFD. (2) Comparing the different inversion models, the RF model has the best inversion effect, and its applicability and inversion accuracy are better than SMLR, ANN and SVM.(3) The best inversion model for As is the AT-RF model, the best inversion model for Cd is the SD-RF model, the best inversion model for Pb is the ASD-RF model, and the best inversion model for Hg is the ASD-SMLR model. This study can provide technical support and reference for the monitoring of soil heavy metal content and pollution evaluation of large-scale alpine and high-altitude lead-zinc mines. (4) The predicted concentrations of Cd, Pb, As and Hg were 124.2, 89.8, 0.70 and 1.24 times higher than the background values of Tibetan soil, indicating that Cd and Pb were the main pollution factors in the soil in the mining area, and were accompanied by the combined pollution of As and Hg.
- 1
Experimental study on the principle of porous equal discharge of paste fillingAbstract:
The multi-hole drainage of the filling pipe can eliminate the self-flow slope angle of the paste, improve the effect of roof jointing in the quarry, and avoid the problem of roof sinking. In order to study the influence of the number of relief holes, hole spacing and hole diameter on the rule of multi-hole equivalent relief, firstly, the diameter of relief holes is initially determined through theoretical analysis, then the homemade multi-hole equivalent relief test device is used to carry out the multi-hole equivalent relief test, and finally the change rule of the pressure and flow rate of the relief pipeline is analysed by numerical simulation method. The results show that compared with single-hole drainage, multi-hole drainage can eliminate the self-flow slope angle and improve the roof catch rate of the quarry. The spacing of holes has the most significant effect on the uniformity of flow relief in the relief holes, followed by the number of holes. When the paste flows in the horizontal pipe section, the static pressure of the pipe tends to decrease along the flow direction, and negative pressure appears at the mouth of the relief hole. After the paste reaches a stable state, the flow rate of each relief hole is basically the same, and the uniformity coefficient reaches 98.8%, which can achieve the equal flow rate of multiple holes.
- 1
Study on damage evolution and failure characteristics of cemented tailings backfill under cycle temperature curingAbstract:
Most of the backfill near the mining working face are in the environment of cycle temperature. In order to study the influence of cycle temperature on the damage evolution and failure characteristics of cemented tailings backfill, the digital image correlation method (DIC) and acoustic emission (AE) technology were used to monitor the cemented tailings backfill after curing at six different cycle temperatures under uniaxial compression, the fracture process and acoustic emission behavior characteristics of cemented tailings backfill at different cycle temperatures were analyzed, and the damage model and constitutive equation of cemented tailings backfill at different cycle temperatures were established. The results show that with the increase of cycle temperature, the compressive strength, elastic modulus and peak strain of cemented tailings backfill increase first and then decrease, and all reach the maximum value at the cycle temperature of 25~40 °C. The DIC full-field strain evolution cloud map of the sample during the compression process can better show the whole process of surface crack evolution. With the increase of cycle temperature, the failure mode of the cemented tailings backfill changes from shear failure to tensile-shear composite failure, and then to tensile failure. The strength of the acoustic emission ringing count signal in the initial compaction stage and the post-peak failure stage is different due to the difference in the cycle temperature, and the sudden change of the acoustic emission ringing count can be used as a precursor to the failure of the backfill; the reliability of the model is verified by the comparison between the theoretical value of the constitutive model and the measured value of the experiment. The research results can provide reference for the design of backfill near the mining working face.
- 1
Development and Application Research of Impact Frequency Acquisition System for Down-the-Hole Drill RigAbstract:
Regarding the collection of impact frequency data for open-pit down-the-hole drilling rigs, based on the drilling sound signal characteristics of the TAIYE-390-Ⅱ open-pit down-the-hole drilling rig, a sampling frequency of 6 kHz, which renders the impact waveforms most distinct, was determined to be advantageous. A method for collecting impact frequencies based on Hilbert transform, Variational Mode Decomposition (VMD), and Savitzky-Golay filtering was proposed, and an impact frequency collection system was developed. This system consists of three main parts: a digital microphone, a data acquisition card, and an industrial computer, which can achieve accurate collection and storage of impact frequencies. By conducting constant wind pressure and constant axial pressure drilling experiments, the reliability of the system was verified. Combined with borehole inspection experiments, the feasibility of identifying structural surfaces in rock formations using impact frequencies was analyzed. The results show that the impact frequency collection system can accurately extract real-time drilling impact frequencies, with an error controlled within 1 Hz, and it complies with the working characteristics of down-the-hole impactors. Meanwhile, the impact frequency exhibits a more pronounced response to rock structure, decreasing by 1 to 3 Hz when encountering various structural surfaces. The research findings have important theoretical significance and practical value in the collection of impact frequencies for down-the-hole drilling rigs and the identification of rock structural surfaces.
- 1
Study on Comprehensive Dust Suppression of Grab Unloading Air Curtain and Negative Pressure SuctionAbstract:
Aiming at the phenomenon of dust diffusion in the process of grab unloading, the comprehensive dust suppression system of dust isolation and negative pressure suction around the air curtain is studied by combining the air curtain dust isolation and negative pressure suction technology. By using CFD-DEM two-way coupling simulation method, the dust isolation performance of the air curtain around is simulated, and it is concluded that the air curtain jet speed of 8m/s can effectively block dust. At the same time, based on the theory of negative pressure suction, the calculation formula of the change of the mass flow rate of suction air with the unloading time is derived by CFD fluid mechanics method, and the simulation and experimental model of grab unloading is established. The distribution map of the discharge plane flow field and the mass flow rate of the hopper mouth are extracted by simulation to reflect the movement of the dusty air flow in the hopper. Through experiments, the variation law of the discharge dust movement and the dust suppression effect are compared before and after the installation of air curtain and negative pressure suction device. The conclusions are as follows: the maximum dust concentration at the hopper mouth is reduced by 738.4mg/m3, the concentration value is reduced by about 95.3%, and the time for dust to completely settle is reduced by 60%, which provides a guiding significance for effectively solving the spread of discharging dust.
- 1
Simulation study of energy evolution and damage characteristics of laminated composite rock samplesAbstract:
In geotechnical engineering, instability damage often occurs in multiple rock layers at the same time, and its different combinations, lithology and other factors will affect the development trend of cracks. The study uses discrete element PFC2D software to establish the specimen model, and simulates uniaxial compression experiments to reveal the effects of the proportion of soft and hard rock layers on the mechanical properties of the specimen, the damage characteristics and the energy evolution law. Research shows: (1) The percentage of hard rock portion in laminated composite rock samples is the main factor affecting the peak strength of the rock samples, and the peak stress of the rock samples gradually increases as the percentage of hard rock portion increases. (2) Both the number of microcracks and the total input strain energy of the laminated composite rock samples achieved their minimum values at the minimum of the thickness ratio (R) of the neighboring rock layers, indicating that a decrease in R leads to an earlier onset of damage in the rock samples. (3) Introducing the elastic energy consumption ratio K in the energy analysis of laminated composite rock samples and verifying that an increase in the value of K can be used as an early warning signal for the occurrence of deformation damage in rocks. (4) The main damage mode of laminated composite rock samples is mixed tension-shear damage, and the macroscopic cracks are basically initiated in the soft rock portion, and then due to the sharp increase of transverse strain in the soft rock portion, the cracks penetrate into the hard rock portion, which reveals that the damage of the rock samples is a gradual loss of bearing capacity. The research results can provide theoretical guidance for practical engineering.
- 1
Feasibility Study of Utilizing Backfilled Roadways as A heat sink for the Cooling of Underground MinesAbstract:
With the increase in mining depth, the heat hazard becomes more prominent, and it is difficult to meet the cooling demands through ventilation optimization alone. The key to implementation of refrigeration cycles in underground mines lies in selecting a suitable heat sink (cold source). This study takes the heat hazard governance in a gold mine in Guizhou, China as an example, and proposes using backfilled abandoned roadways as a heat sink to accommodate heat transferred from the working faces or the fresh air inlet. The thermal properties of the backfill material and surrounding rock samples of the abandoned roadway were measured; a numerical model of heat rejection to the abandoned roadway was established. Long term application scenarios under two operational modes and three heat exchange buried pipe layouts were simulated to analyze the variation of outlet water temperature, heat transfer power and coefficient of performance of the system. The study indicates that merely increasing the number of heat exchange pipes could not significantly improve the technical and economic performance; and intermittent operation mode was beneficial for mitigating the heat accumulation risk and improving heat transfer intensity of U pipe, which is crucial for the long-term and sustainable operation of the system. Based on the cooling load of a working face, the scrap value of heat transfer power was determined. The feasibility of different application scenarios was compared and evaluated based on heat transfer intensity of U pipe and the total accommodated heat capacity of the heat sink within its service life span. The research results provide a scientific support for the reuse of abandoned mines and heat hazard governance by green and effective approaches.
- 1
Stability analysis of subsequent filling body in open field and design of belt filling structureAbstract:
Regarding the stability of subsequent backfill bodies in mid-segment mine rooms, which lacks systematic research, the design of backfill strength mainly relies on experience and engineering analogies. In an effort to refine these practices, advanced techniques were employed at an iron mine to analyze mechanical parameters for various backfill compositions. This led to the development of a large-scale model for evaluating consecutive backfill operations across seven mine rooms. Numerical simulations helped to map out the plastic zones, stress distribution, and deformations after each mining phase, including the dynamics of potential slip surfaces within the backfills. It was found that backfill instability and failure predominantly occur in the lower sections, around the midsection, and near the ceiling. Consequently, a zonal backfill strategy is proposed, advocating for targeted reinforcement at identified weak points rather than uniform strength across all areas. This approach not only improves overall stability but also considerably reduces backfill costs.
- 1
Numerical Simulation and Sensitivity Analysis of CO2 Enhanced Gas Displacement in Coal SeamAbstract:
Coal seam gas injection displacement extraction is an effective measure to reduce the gas content of coal seam. The engineering parameter setting and actual working conditions of coal seam in the process of gas injection displacement will affect the effect of displacement extraction. In order to explore the influence of various factors on the effect of CO2 enhanced displacement extraction and the sensitivity relationship between various factors. Using COMSOL Multiphysics numerical simulation software, the model of gas displacement by CO2 injection in coal seam is established. The four factors of gas injection pressure, coal temperature, coal permeability and coal load are analyzed. The results show that the increase of gas injection pressure and permeability strengthens the displacement, and the increase of temperature and load weakens the displacement. The sensitivity of the factors affecting the amount of gas displacement is coal permeability > gas injection pressure > coal temperature > load. The influence of coal permeability on the amount of gas displacement is 5.97 times that of gas injection pressure, the gas injection pressure is 15.30 times the coal temperature, the coal temperature is 1.65 times the load. The order of displacement velocity sensitivity is coal permeability > gas injection pressure > load > coal temperature. Effect of permeability on displacement rate is 9.22 times of gas injection pressure, the injection pressure is 32.66 times of the load, load is 3.20 times of coal temperature. Therefore, in order to achieve better displacement effect in practical engineering, it can be considered from the perspective of increasing coal permeability and increasing gas injection pressure.
- 1
The optimization and application of backfill mix ratios in the second mining area of the Peji Copper-Gold MineAbstract:
To meet the backfill strength requirements for the second step of retreat mining in the Peji Copper-Gold Mine area in Serbia and to reduce the economic cost of backfilling, it is necessary to optimize the backfill plan and the mix ratios of the backfill body for the mining area. Theoretical calculations have been used to preliminarily determine the strength of the backfill body in different parts of the second mining area, and several sets of indoor backfill body tests have been conducted. The tests indicate that as the mass concentration and the cement-to-sand ratio increase, the uniaxial compressive strength of the backfill body gradually increases. When the mass concentration is 68% and the cement-to-sand ratios are 1:6 and 1:8, the strength of the backfill body can meet the calculated requirements for backfill strength. Based on this, on-site industrial trials were carried out. The results of the on-site industrial trials show that using a backfill plan with a cement-to-sand ratio of 1:6 at the bottom of the mining area and 1:8 at the top and middle can meet the strength requirements for the second step of retreat backfilling. At the same time, the backfill cost is reduced by 2.53 yuan/t compared to the original backfill mix ratio. The research results can provide a reference for the backfill plans of similar mines.
- 1
Research Progress of Mineral Processing Wastewater Treatment TechnologyAbstract:
The effective treatment of mineral processing wastewater (MPW) is of great significance to reduce environmental pollution, save water resources and promote the sustainable development of mining industry. Based on the analysis of the source, characteristics and harm of MPW, the research progress of physical, chemical and biological treatment of MPW was summarized in this paper. Physical methods such as coagulation-flocculation and adsorption are slow and have limited effectiveness in removing complex pollutants. Advanced oxidation process such as photocatalysis, Fenton process and ozone process are expected to become an important development direction of MPW treatment in the future because of their simple operation and high efficiency. Biological method has the obvious advantage of no secondary pollution, but it is urgent to solve the problems of long processing time and high requirements of microorganisms on living environment. In the future, different processes can be combined to form an efficient treatment technology system, at the same time, MPW treatment technology for reuse needs can be actively developed.
- 1
Study on Optimization of Settling Process and Microstructure of Flocculant used in Benxi Iron TailingsAbstract:
In order to solve the problem of slow settling of iron tailings in Benxi, the appropriate flocculant was selected through flocculant optimization test, and the influence of slurry concentration, flocculant unit consumption and slurry pH on flocculation settling was investigated through single factor test. The micro-structure of the settling was observed, and the settling rules of iron tailings were summarized. The results show that the natural settling basically end at 600 min, and after reach the settling critical point, the sediments go through the main consolidation stage and secondary consolidation stage. The main consolidation stage end at 2000 min, the secondary consolidation stage end at 3500 min, and the clarification area height then remain stable. The flocculation effect is the best when the flocculant is APAM, the slurry concentration is 15 %, the flocculant unit consumption is 20 g/t and the slurry pH=9. The solid content ratio in 10 min under this condition is 233.13 mg/L, and the settling ratio in 10 min is 67.15 %.
- 1
Research on loose boundaries in the affected area of collapse mining based on the combination of TRT advanced detection and geological drillingAbstract:
The underground rock conditions of a copper nickel mine are poor. In the early stage, the collapse mining method was used to recover mining stone resources,. Due to the long exposure time of the collapse mining site and the influence of mining disturbance, the mining area experienced roof collapse and side slope collapse before treatment, resulting in weakened mining technology conditions for the upper rock and making it impossible to safely extract over a million tons of ore resources under the current situation. Based on this, a detection method combining TRT advanced detection and geological drilling was adopted. The loose boundary roof elevation of the mining area affected by the bottom pillar collapse method was detected to be 760m level, the upper wall boundary was approximately vertical, and the lower wall boundary was inferred based on a rock movement angle of 60 °. The loose boundary roof elevation of the mining area affected by the non bottom pillar collapse method was 755m level, and the situation of the upper and lower walls was similar to that of the mining area affected by the bottom pillar collapse method.The detection results can provide a basis for the selection of mining methods, mining preparation engineering layout, support methods and their strength application for the ore resources in the area, ensuring safe and efficient underground production.
- 1
Section Continuous Mining StopeWANG Qihu 1,XU Tianchao 1, ZHANG Zenggui2 ,ZHANG Guoquan2,ZHANG Yong2,FENG Qing2Abstract:
Daye Iron Ore is in the continuous mining stage of -270 m~-360 m middle section, the remaining ore volume in the middle section of -270 m is insufficient, and the stope production capacity will be insufficient in the early stage of -360 m middle section, and the mine output is unstable, which is difficult to meet the design capacity of 1.3 million t/a per year. According to the process characteristics of the upper horizontal layered backfill mining method and the subsequent filling method of the empty field in the staged rock drilling stage, based on the distribution of each stope, the mining process and the current situation of the mining equipment in the middle section of Daye Iron Mine -360 m, the stope mining equipment scheduling optimization model was established, the genetic algorithm was used to simulate the most compact process arrangement, and the maximum number of simultaneous stopes was solved based on the equipment utilization function, and two mining schemes were proposed. The results show that when the number of stopes that can be mined at the same time in the middle section of -270 m is 3, and the number of stopes that can be mined at the same time in the middle section of -360 m is 5, the maximum daily production capacity reaches 4218 t/d. Further optimization of stope layout, the results show that the mining scheme of the two middle sections is more efficient, the ore production is more stable, the annual production capacity reaches 1.437 million tons, and the comprehensive production capacity exceeds the target value by 10.5%, which is helpful to solve the problem of insufficient production capacity and unstable production of Daye Iron Mine in the current state of two middle sections.
- 1
Optimization of Stope Structure Parameters Using Post-fill Mining Method in the Broken Ore Body of Pakrut Gold MineAbstract:
Aiming at the problems of low production capacity, many cutting works, high cost, poor working environment, many safety hazards and high risk in the mid-section quarry of 2 230 and 2 170 in Pakrut Gold Mine, the study has obtained a reasonable size of the quarry by adopting Mathews' stabilization graphic method on the basis of rock physical and mechanical property tests and RMR (rock mass geomechanical classification). On this basis, the mine was changed from 4 low sections of 12 m to 2 high sections of 21 m. Taking the mining width as a variable, the FLAC3D software was used to simulate the stability of the mine under the condition of "mining in three intervals", and the optimal width of the mine was determined to be 11-12 m. Finally, through the industrial test, the collapse of the optimized mine was analyzed, as well as the economic and technical indexes; The results show that the production capacity of the optimized quarry is increased by 20%, the loss rate is reduced by 4.67 percentage points, the depletion rate is reduced by 3.25 percentage points, the kiloton mining and cutting ratio is reduced by 36%, and there is no collapse phenomenon in the quarry, which is up to the expectation. The study shows that the optimization method of structural parameters of the quarry based on rock physical and mechanical property test and RMR rock classification, Mathews stability graphical method and FLAC3D numerical simulation, and finally verified by industrial test has high application value.
- 1
XU Jiang1,2 ,CUI Mengqin1,2 ,PENG Shoujian1,2 , CHEN Yian1,2 ,RAO Haokui1,2 ,CAO Qi1,2Abstract:
Creep is a common rheological behavior of surrounding rock in rock engineering, especially under the action of seepage water pressure, which poses a serious threat to the safety and service life of the project, so it is very important to maintain the long-term stability of the project. Creep tests under different hydraulic gradients were carried out by using seepage-stress coupling servo control loading system to explore the creep characteristics and seepage characteristics of sandstone. Combined with 3D digital image correlation technology (3D-DIC), the evolution law and deformation localization characteristics of micro-cracks in sandstone were studied. At the same time, the crack damage characteristics of sandstone were explored based on CT scanning technology. The test results show that: (1) The greater the hydraulic gradient, the greater the creep deformation, the faster the growth rate of micro-cracks, and the more obvious the change of strain field nephogram. Compared with the axial strain field, the larger strain point and strain localization appeared earlier in the radial strain field nephogram. (2) The greater the hydraulic gradient, the greater the strain increment, the faster the strain change rate and the shorter the creep life of sandstone. By establishing virtual strain gauges, it was found that the strain changes inside and outside the failure zone were inconsistent, indicating that there was localization in the creep deformation process of sandstone. (3) Under the low hydraulic gradient, the pores and fractures were more tightly closed, the seepage channels were reduced, and the flow rate was decreasing. Under the high hydraulic gradient, the damage was accumulating, the seepage channels were increasing and the flow rate was increasing. (4). It could be observed in the CT scan that the main crack ran through the whole specimen, which led to the failure of sandstone, and at the same time generates secondary cracks and promoted the crack propagation. Near the end with higher seepage pressure, there were more secondary cracks in sandstone, forming a complex crack network structure.
- 1
Study on the rupture characteristics and evolution law of water-bearing longitudinal fissure coal rockAbstract:
Coal rock's mechanical properties and fracture characteristics are heavily influenced by its longitudinal fractures and water content. Acoustic emission monitoring equipment was used to conduct a uniaxial compression test on coal rock with longitudinal fissures containing water. The goal of this research was to examine the effect of longitudinal fractures on the peak stress, peak strain, elastic modulus, and failure mode of coal rock in a water-bearing condition, as well as the link between water content and mechanical characteristics of coal rock. The study reveals the significant difference in failure modes between intact coal rock and longitudinal fractured coal rock: intact coal rock tends to self-sustaining failure, while longitudinal fractured coal rock shows non-self-sustaining failure, and the peak strength decreases by about 20 %. In addition, during the loading process of longitudinal fractured coal rock, when the loading time reaches 48.5 % -62.6 %, the acoustic emission events will agglomerate in the failure center area of the coal rock. It is also found that the relationship between water content and soaking time is ωa = 0.82lnt + 0.31, and the relationship between peak strength and water content is σ = 19.77-3.11ωa. These experimental results not only provide a basis for the qualitative description of the failure mode, failure range, and failure strength of coal rock but also have important reference value for exploring the deformation and failure mechanism of coal rock and the stability analysis of underground engineering.
- 1
Numerical Simulation Study on the Pipeline Transportation Status of Tailings Slurry from a Tin Mine in Yunnan Based on ANSYS-FLUENTAbstract:
During the pipeline transportation of tailings slurry from the beneficiation plant to the filling preparation station, changing the feeding parameters will cause changes in the spatial distribution of tailings solid particles in the pipeline, thereby affecting the safety and stability of slurry pipeline transportation. The study focuses on the transportation of sulfide tailings from a tin ore beneficiation plant in Yunnan to the filling preparation station through pipelines. The rheological parameters of the tailings slurry were obtained through rheological tests. ANSYS FLUENT numerical simulation software was used to simulate and analyze the pipeline transportation of tailings slurry. The relationship between the relative height of the bottom bed layer and the feeding parameters was fitted, and a three-dimensional relationship model between the relative height of the bottom bed layer, feeding speed, and volume concentration was established. The results show that: ① The three-dimensional relationship model between the relative height of the bottom bed and the feed rate and volume concentration has a good fitting effect; ② Most of the coarser particles with a size of +120 mesh (125 μm) have sedimentation phenomenon in the bottom bed layer. Fine particles with a size of 120 and 200 mesh (100 μm) have sedimentation phenomenon at the bottom of the pipeline when the feeding speed is 1 m/s. They are distributed in the carrier layer when the feeding speed is above 2 m/s. Fine particles with a size of -200 mesh (75 μm) are all distributed in the carrier layer; ③ There is water in the boundary layer of the top wall of the pipeline, as well as a slurry formed by some extremely fine particles and water, which together form the boundary layer; ④ The radial volume concentration variation of tailings slurry can be divided into four regions. Among them, there is a gradient decreasing effect in region a, region b gradually increases to stability, region c reaches its maximum value and remains stable, and region d gradually decreases.
- 1
Anchor hole localization methods in multi-scale complex environmentsAbstract:
Coal mine tunneling anchor operation is a key factor affecting the efficiency of tunneling, how to accu-rately determine the location of anchor holes under the tunnel conditions with many interfering factors is one of the key links to improve the anchoring speed. At present, most of the studies on anchor hole locali-zation consider the interference factors in a single way, and the influence of complex factors on anchor hole identification under multi-scale changes has not been studied yet. Therefore, an improved anchor hole localization method under multi-scale complex environment of YOLOv8s is proposed. First, in order to simulate the real conditions of coal mine roadways, three levels of influence scales are established for the main factors affecting anchor hole localization, such as light intensity, dust and water mist concentration, shooting distance, etc., and the initial data set is constituted by the combination of each influence factor. Image preprocessing operation is performed before anchor hole recognition to optimize the overall image quality. Then, the YOLOv8s deep learning network model is improved by adding the multi-scale void at-tention mechanism (MSDA), which improves the feature extraction ability of the model for small targets under complex conditions. Finally, the pixel coordinates of the anchor hole center are calculated to find its actual 3D coordinates. The actual detection results show that: The average detection accuracy of the im-proved YOLOv8s model reaches 91%, which is 5% higher compared to the YOLOv8s model; the improved YOLOv8s model has a better detection ability, which can accurately detect the location of the anchor holes in the image under the interference of the influencing factors of different scale combinations; the number of frames per second (FPS) of the processed image of the improved YOLOv8s model is maintained at 171 frames/s, which can meet the real-time requirements of the model detection function.
- 1
Study on the Failure and Permeability Evolution of Mining Overburden in Makeng Iron MineAbstract:
In order to study the damage and seepage characteristics of overlying rock mass caused by underground mining in Makeng Iron Mine, this paper relies on the mining project of orebody west of line 60 of the west mining section of Makeng Iron Mine, adopts FLAC 3D numerical simulation software to build a fluid-solid coupling model, simulates the mining process of filling mining method of orebody west of line 60 of the west mining section, and reveals the distribution characteristics of plastic failure zone of overlying rock mass after mining. The seepage evolution law of mining overlying rock mass is investigated, and the permeability of stope after mining is evaluated. The research shows that the mining of ore body leads to obvious plastic failure zone around the stope, fault, rock bridge and structural fracture zone, local failure occurs between stope, fault and rock bridge of stope, and even through failure. The main plastic failure zone is distributed in a local scope, and the failure situation of stope, fault and Xima River is not formed. With the continuous advance of filling mining, the water conductivity of mining overlying rock mass continues to increase, the seepage velocity of the roof is greater than that of the side, the permeability is greatly affected by the fault and broken rock mass, and the isoline of pore water pressure continue to spread towards the fault direction. Nevertheless, a complete drainage pathway, from river to fault to rock bridge to mining field, does not ultimately form in the seepage field.
- 1
Risk assessment of water inrush in coastal gold mines based on moment estimation theory and GRA-VIKORAbstract:
In response to the randomness and fuzziness of water inrush risk in coastal gold mines, as well as the complex correlation between evaluation indicators, a GRA-VIKOR evaluation model for water inrush risk in coastal gold mines based on moment estimation theory was established to make the risk assessment more scientific. Firstly, based on engineering practice, 10 typical influencing factors were selected from two aspects: engineering geology and hydrogeology, and an evaluation index system was constructed; Secondly, four single weighting methods, namely IAHP method, G1 method, EM method, and I-CRITIC method, were used to calculate the subjective and objective weights of the indicators. Based on moment estimation theory, the integrated optimization method of subjective and objective weights was improved; According to the GRA-VIKOR principle, analyze and determine the risk status of water inrush by calculating the comprehensive evaluation value; Finally, the model was applied to the risk assessment of water inrush in 9 middle sections of a gold mine in Shandong Province, to determine the risk level and ranking of water inrush in each middle section. The results indicate that the evaluation results of the model are accurate and reasonable, in line with reality, and can provide reliable ideas for the risk assessment of water inrush in coastal gold mines.
- 1
Application Research on High Level Open Stoping with Subsequent Waste Rock Filling Mining Method for Thick Ore Body under Group of Mined AreaAbstract:
Through the analysis and research on the problems of poor safety conditions and large loss of top pillars in the mining of olive-type thick ore-body under the group of mined area，it was concluded that a high-level open stoping with subsequent waste rock filling mining method which had a security barrier pillar about 25m was better to mine this thick ore-body. FLAC3D was used to simulate and analyze the structural parameters of high-level stope，and also the influence of high-level mining on the stabilities of upper mined area，security barrier pillar and upper and transportation gateway. The results show that the stope size of 40m×ore body thickness×75m and the pillar size of 10m were suitable，the stability of the big mined area was good under the protection of the security barrier pillar，and the transportation gateway of 650 needs to be changed because of the poor stability near the mine room. Through the field industrial test，the high-level mining method saved 240m of the mining preparation engineering and the mining preparation period was short. The ore was recovered by 48,000 tons without retaining the top pillar，and the stope production capacity reached 1400t/d due to synchronous blasting of large diameter deep hole and upward fan-shaped hole，the ore recovery rate and production efficiency were greatly improved which provided technical support for the mine to be put into production as soon as possible.
- 1
Research on High-Quality and Low-Cost Backfilling Process for Large Lean Iron Ore MinesAbstract:
This study focuses on developing a cost-effective backfilling technology for large low-grade iron ore mines. The key factors for successful whole-tailings backfilling are matching capacity, stable concentration, and cost control. To reduce backfilling costs, it is crucial to improve operational efficiency. The proposed solution introduces a backfill preparation system with a capacity of 200–220 m3/h, capable of delivering slurry at both transient and sustained high flow rates. Moreover, the concentration of the supplied slurry determines the backfilling material concentration. The system is equipped with two large-volume sand silos, each with a volume of 2020 m3, enabling efficient storage, slurry preparation, and discharge. This facilitates high-concentration backfilling at a stable concentration of approximately 72%. The system can backfill over 4,000 m3 in a single operation and sustain continuous backfilling for 24 hours through recycling, maintaining a balance between efficient mining and backfilling. Furthermore, the study investigates the application of a novel cementitious material, which not only satisfies the design strength requirements for underground goafs, similar to mine-use cement, but also achieves a substantial reduction in the ratio of filling materials. This reduction translates to a cost savings of RMB20.01 per cubic meter of structure, attributed to the decreased usage of cementing agents. Given the annual volume requirements for goaf backfilling in the mine, adopting this new cementitious material has the potential to yield substantial savings of around RMB44.68 million per year in backfilling expenses.
- 1
Research on LightGBM flotation tailings ash prediction model based on genetic algorithm optimizationAbstract:
In order to improve the level of on-line ash detection in the process of coal slime flotation, this research studied the prediction of tailings ash content in the process of coal slime flotation, and proposed a soft measurement method. The Lightweight Gradient Elevator (LightGBM) algorithm model was used to model the ash prediction, and combined with the genetic algorithm to optimize the parameters, a LightGBM flotation tailings ash prediction model based on genetic algorithm optimization was designed. The model training dataset was constructed by collecting the production process data, including slurry flow, concentration, foaming dose, capture dose and dry slime volume. The experimental results show that the average absolute error of the prediction results of the model is 0.72, which is 11.1% higher than that of the unoptimized LightGBM model, and 15.8% lower than that of the best decision tree model in other models. This further proves the effectiveness of the proposed model in the prediction accuracy of tailings ash content, and provides new technical support for the realization of intelligent flotation.
- 1
Optimization of Water Injection Parameters for Rock Burst Prevention and Control in Shaiqihe Phosphate MineAbstract:
The Shaiqihe phosphate mine in Yichang, Hubei has entered deep mining, and rock burst disasters are frequent in the excavation face. Water injection is used to soften the surrounding rock in the working face to prevent rock burst, and reasonable water injection parameters affect the effectiveness of rock burst prevention and control. This article analyzes the relationship between water content and rock burst tendency of phosphate rock under uniaxial compression experiments under different water content states based on the rock strength brittleness coefficient method; Numerical simulation was used to explore the distribution characteristics of water content in the surrounding rock of the working face during water injection. The effective wetting distance of the working face was defined as the basis for designing water injection parameters, and the optimal water injection parameters for the excavation working face of the Shaiqihe phosphate mine were determined. The results show that when the water content of the phosphate rock reaches 0.424%, the phosphate rock layer is in a moderate rockburst tendency, and the change in strength brittleness coefficient B with water content w is no longer significant after water injection. When the water injection time is 1 hour and the drilling depth is 10 meters, the effective wetting radius growth rate is the highest, and the water injection effect is the best. The research results have certain guiding significance for improving the water injection process parameters of phosphate rock and reducing the risk of phosphate rock burst.
- 1
Optimization and Application of Unloading Mining Scheme for Deep Well Deposits Based on Critic Weighting MethodAbstract:
With the gradual depletion of shallow mineral resource development, deep well deposits are bound to become the main position of China's strategic resource development, but the "three highs and one disturbance" faced by deep well mining will restrict the safety of deep well deposit mining, greatly increase the difficulty of large-scale mining, and the choice of reasonable mining methods has become the premise of efficient and safe mining of deep well deposits. The Critic weighting method is introduced to study the comprehensive optimization evaluation model of deep well unloading mining scheme. Taking a deep super large deposit in China as the engineering background, four groups of unloading mining schemes are proposed, and the comprehensive evaluation model of Critic objective weighting method for deep well unloading mining scheme is established. The results show that the panel layer unloading large section approach mining scheme （Scheme 4）is the optimal deep well unloading mining scheme. Field industrial test was carried out based on the optimized mining scheme of the panel layer unloading large section approach mining scheme. The results of the mining industrial test of the large section approach method with the unloading of the panel layer show that the recommended mining scheme has the advantages of high unloading efficiency, large production capacity and low loss index, which objectively confirms the feasibility and applicability of introducing Critic weighting method into the optimization of deep well unloading mining scheme, and provides a deep well unloading mining scheme optimization idea for domestic mines in China.
- 1
Numerical simulation study of desorption performance of walking tracks based on AnsysAbstract:
Reasonable nozzle structural parameters are crucial for the desorption performance of walking tracks of deep-sea mining vehicles. Taking the adherent substrate between the walking tracks of the mining vehicle as the research background, numerical simulation of the walking track desorption effect is carried out by using Ansys software for the structural parameters and layout design of the nozzles, and the optimal parameters of the nozzles for the desorption of the walking tracks are determined from the calculations and analysis of the velocity of jet impacting on the track teeth, the change rule of velocity with displacement, and the distribution of the dynamic pressure on the surface of the track plate. The results show that the cavitation effect of the nozzle is very weak when the underwater depth is 5000 meters, and the design of the nozzle for deep-sea submerged jets may not consider the cavitation effect; Increasing the diameter of the nozzle can significantly increase the length of the core area of the jet. For diameter straight nozzles which are 10mm,20mm and 30mm, the jet velocity starts to decay rapidly around at 0.09m, 0.2m and 0.31m respectively; seven 90°jets of 30mm diameter straight nozzles have the best detachment performance of the walking track. Numerical simulation results can provide a strong theoretical basis for the study of the desorption performance of seafloor traveling tracks of deep-sea mining vehicles.
- 1
Study on the Influence of Wind Speed on Dust Diffusion and Mass Concentration in Low-concave Open-pit Minesjiangyuwen, 柯丽华, 张光权, 余晓轲, 贺振祥, 黄兆云
Abstract:
In order to reduce the adverse effects of loading dust on the occupational health of workers in low-concave open-pit mines and formulate effective dust reduction measures, the Euler-Lagrange model and Fluent numerical simulation method were used to research the effects of different wind speeds on the diffusion and mass concentration distribution of loading dust near the side slope of low-concave open-pit mines based on the theory of gas-solid two-phase flow. The flow separation occurs when the airflow passes through the steps and the low-speed turbulent zone, counterclockwise structural vortex and clockwise small vortex in the carriage are formed to make the flow field structure at the mining horizontal of -12 meters and near the carriage very complicated. With the increase of wind speed, the shorter the aggregation time of the loaded dust in the compartment, the speed of the loaded dust spreading with the structural vortex increases, the longer the distance of the spreading of the pollution effect along the X-axis, the maximum mass concentration of dust aggregated in the structural vortex is significantly reduced, the mass concentration of dust in the compartment is higher than 100mg/m3, the mass concentration of dust in the respiratory zone at the height of the dust along the course of the diminution of the mass concentration of dust and dust mass concentration decreases in the reduction of the amplitude of the dust mass concentration. According to the numerical simulation results and the occupational exposure limit of concentration dust 8 mg/m3, the area of the dust pollution is determined to be within 15 meters in front of the front of the car. The dust reduction measures are formulated such as using fog gun trucks, sprinkler trucks and equipping protective equipment and good dust removal effect is obtained.
- 1
Uniqueness of displacement back analysis for transversely isotropic viscoelastic rock massesAbstract:
In order to study the uniqueness of the displacement back analysis of isotropic viscoelastic rock mass, an analytical solution for the radial displacement of a circular roadway in a transversely isotropic viscoelastic rock mass is derived from the principle of elastic and viscoelastic correspondence principle. The study investigates the uniqueness of the inverse analysis of displacement in transverse isotropic rock mass when considering viscoelasticity by relying on the condition of parameter recognizability. The results show that no matter how many measuring points are set, all the 7 parameters can not be determined simultaneously. It is possible to determine other parameters only when there are at least 3 parameters are known in advance. The values of the vertical ground stress and the transverse ground stress have a significant influence on the identification of inversion analysis. The fewer the parameters to be solved, the more recognizable the parameters are. The initial ground stress parameters have the best identifiability, followed by Poisson's ratio, modulus of elasticity and viscosity coefficient on the isotropic surface, and the modulus of elasticity and viscosity coefficient normal to the isotropic surface are the worst. The research results provide a theoretical basis for the back analysis calculation of rock mass parameters.
- 1
Research and Practice on Low Disturbance Backfill mining Plan for Shallow Buried Pillar Resources in Xianglushan Tungsten MineAbstract:
In order to improve the utilization rate of point pillar resources in Xianglushan tungsten mine and control the impact of shallow buried and deep point pillar resource recovery, firstly, the technical conditions for residual point pillar mining underground are analyzed, and combined with the current common point pillar recovery plans and selection principles, two filling recovery plans suitable for shallow buried and deep point pillar resources in Xianglushan tungsten mine are studied and determined; Then, using three-dimensional numerical calculation methods, displacement and plastic failure calculations were conducted for each scheme at burial depths of 50m, 100m, 150m, and 200m. At the same time, in order to reduce the impact of underground blasting on building vibration, the relationship between the maximum allowable single segment explosive amount and spatial distance for underground blasting was analyzed and calculated; Finally, the backfilling plan was validated through the design and industrial testing of the 610 underground mining plan in the Xianglushan tungsten mine. The research results indicate that during the implementation of the mining plan, there were no significant changes in ground pressure and displacement monitoring data, and the stability of the goaf was good. The residual ore recovery rate within the height of the goaf in the panel mining area reached about 38%, and good results were achieved in industrial experiments.
- 1
Rock mass quality classification and strength estimation based on the Hoek-Brown strength criteria for the Shanhu Tungsten MineAbstract:
The rock mass strength is a key mechanical parameter for the safety and stability analysis of mining. In this paper, combined with the key project of small-scale mechanized mining technology in Shanhu Tungsten Mine, the rock mass quality classification and stability evaluation are carried out by three different methods on the basis of detailed investigation of the rock mass structural plane, and then the rock mass strength is estimated based on quantitative GSI and Hoek-Brown Criteria to obtain accurate and reliable rock mass strength parameters. The research results are as follows: (1) The structural plane characteristics of the limestone rock mass are identified in detail. The dominant joint plane strikes NNW-SSE or NW-SE, inclined NE or SW, dip 70°~80°. The volume joint number Jv is 7.07~9.88, the integrity coefficient Kv is 0.55~0.63, and the integrity evaluation is relatively intact. (2) The rock mass quality classification is carried out by the BQ, Q and RMR methods. The [BQ], Q and RMR89 value of limestone rock mass are 380.96, 5.58 and 59, respectively, and the rock mass quality is grade Ⅲ or general. (3) According to the BQ classification results, when the span of roadway or stope is less than 5m, the surrounding rock can be basically stable. According to the Q classification results, the maximum unsupported span of roadway or stope is about 6.35m. According to the RMR classification results, when the roadway or stope span is 5m, the average standing stability time of surrounding rock can reach 7 days (1 week). (4) Based on quantitative GSI and Hoek-Brown criteria, the Hoek-Brown strength parameters and equivalent Mohr-Coulomb strength parameters of limestone rock mass are obtained, which can provide accurate and reliable mechanical parameters for mining design and stability analysis.
- 1
Study on the effectiveness of multi-source solid waste combined with microorganisms for soil carbon sequestration remediation in arid mining areas of northwest ChinaAbstract:
In order to improve the problems of nutrient-poor soil and limited carbon sequestration capacity in the arid mining areas in Northwest China, field experiments combined with the static box method were used to improve the quality of sandy degraded soils in the coal-mining subsidence areas by using multi-source solid waste (coal gangue and sludge compost) combined with carbonate-mineralising bacteria. The results showed that the addition of solid waste and carbonate mineralising bacteria promoted the growth of alfalfa and the development of its root system, and increased the carbon and nitrogen content of alfalfa; the combination of solid waste and carbonate mineralising bacteria significantly increased the carbon and nitrogen content of the soil and the activities of enzymes related to carbon and nitrogen metabolism of soil microorganisms, and the amelioration effect of the group of the combination of solid waste and carbonate mineralising bacteria was better than that of the group of the treatment group of the bacterial agent applied alone. The net ecosystem exchange rate (NEE) was reduced and the total primary productivity (GPP) of the ecosystem was increased in the groups with the addition of solid waste and carbonate-mineralising bacteria. Structural equation modelling indicated that the addition of multi-source solid waste and carbonate-mineralising bacteria was an important factor influencing the total ecosystem productivity (GPP). Therefore, the application of multi-source solid waste and carbonate mineralising bacteria in soil remediation in arid mining areas in Northwest China has the potential to improve quality and efficiency, sequester carbon and reduce emissions.
- 1
Experimental Study on Efficient Separation and Reduction of Tin Loss from Magnetite and Pyrrhotite in Dulong Mining AreaAbstract:
The efficient separation of magnetite and pyrrhotite has always been a technical challenge in mineral processing. The iron concentrate produced by Hualian Zinc Indium Mineral Processing Plant mainly consists of magnetite and pyrrhotite, which have problems such as excessive sulfur content, poor quality, low sales prices, and high tin metal loss rate in the iron concentrate. The process flow of using iron coarse concentrate+weak magnetism+pre demagnetization+grading and re grinding+pre demagnetization+flotation desulfurization+magnetic separation achieves efficient separation of magnetite and pyrite. Finally, a high-quality iron concentrate with a grade of 66.62% and a sulfur content of 0.65% was obtained, producing a high iron sulfur concentrate with a sulfur content of 25.61%, a recovery rate of 96.06%, and an iron content of 59.52%. At the same time, the loss rate of tin in the iron concentrate was reduced, and a sulfur concentrate with a tin enrichment ratio of 3.69 times was produced. The main process used a shaking table separation to produce tin coarse concentrate and tailings, thereby achieving efficient separation of pyrrhotite and magnetite and reducing the loss of tin metal.
- 1
Ecological Surface Fractal Analysis and Evaluation of Mine Ecological Restoration AreaAbstract:
The ecological restoration of mines is of great significance to promote the sustainable development of mines. In order to objectively and comprehensively evaluate the effect of mine ecological restoration, takes Xishan Ecological Restoration Area as the study area and analyzed multiple landscape pattern indexes at both global and local scales by combining fractal theory and the moving window method to obtain the spatial and temporal variation of the surface condition grade, used the change rate model and spatial variation atlas to quantitatively describe the spatiotemporal variation of the surface condition level in the study area. The results shows that the overall surface condition of the study area is in a stable and improved trend, and the mine ecological restoration work has achieved remarkable results. However, the surface condition grade around the artificial landscape patches in the northern and eastern parts of the study area may degrade, and it is necessary to strengthen the supervision measures. The analysis and evaluation method based on fractal theory can reflect the objective reality more objectively, and the research results can provide a reference for the sustainable development of mines.
- 1
Effect of composite dry sorter on iron reduction efficiency of coal from Black Hills mining areaAbstract:
Zhundong coal is a high-quality coal for power use. However, the unique coal-forming environment of Zhundong coal leads to the high content of alkali metal and alkaline earth metal elements in Zhundong coal, and the high content of iron and calcium elements in some mining areas; these elements in the process of coal combustion will produce slagging and staining, which will affect the safe production of the power plant, and even lead to boiler shutdowns, which greatly restricts the development and utilization of Zhundong coal. Therefore, in order to realize the efficient and clean utilization of Zhundong coal and fundamentally alleviate the problem of boiler slagging and staining, it is necessary to fundamentally reduce the content of alkali metals and iron in Zhundong coal. According to the existing research and this paper demonstrates that the alkali metals and iron oxides in coal ash mainly come from the associated minerals of coal, so by reducing the content of coal ash through sorting, the iron elements in coal can be removed to a certain extent. In this paper, through the comparative study of the existing more mature several kinds of sorting technology found that, because of the constraints of the West Black Mountain mining area coal brittle, easy to break in contact with water, so it is difficult to raise the quality of the utilization of wet sorting technology; magnetic separation technology equipment cost is high and the feed size is small, not only to increase the cost of crushing, but also does not comply with the actual production and sales situation of the coal mines; the composite dry selector level of profit, production is higher, in line with the actual production needs of the coal mines; to sum up the composite dry selector profit level, output, meets the actual coal mine In summary, the composite dry separator sorting technology is suitable for the quality of raw coal and iron reduction in the West Black Mountain mining area. Compound dry separator sorting technology can reduce about 30% of iron oxide in the raw coal ash in the study area, and after the sorted coal is de-powdered with 90% screening efficiency, it can further reduce the iron oxide content in the coal ash, so that the iron oxide content in the commercial coal can be greatly reduced, thus meeting the market demand.
- 1
Experimental Study on Improving the Molybdenum Beneficiation Recovery Rate of a Tungsten Molybdenum Polymetallic OreAbstract:
In response to the characteristics of magnetic iron, low and fluctuating molybdenum grade, and high content of argillaceous gangue in the raw ore of a tungsten molybdenum bismuth polymetallic mine in Hunan, a focus was placed on improving the recovery rate of molybdenum beneficiation, and experimental research on optimizing the beneficiation process and reagent system was carried out. The research results show that using the "magnetic first flotation molybdenum bismuth and other floatable mixed flotation residual sulfide ore" process, CD-N is the adjusting agent, B-8 and butyl xanthate combination is the sulfide ore collector, F6 is the foaming agent. The laboratory closed circuit test obtained molybdenum bismuth mixed concentrate with Mo grade of 3.46%, Bi grade of 2.03%, Mo recovery rate of 85.40%, and Bi recovery rate of 80.05%, which increased the molybdenum recovery rate by nearly 5 percentage points compared to the production conditions on site, achieving efficient recovery of molybdenum, And it does not affect the subsequent scheelite flotation, providing a technical basis for the subsequent renovation and expansion of the tungsten molybdenum polymetallic mine.
- 1
MO Minkun 1,2, TENG Jiahuang 1,2, LIANG Chaoxu1,2,HUANG Fuchuan1,2,*(1. School of Mechanical Engineering, Guangxi University, Nanning 530004, China;Abstract:
In order to improve the magnetic field performance and reduce the manufacturing cost of the flat magnetic separator,the finite element method(FEM),response surface method(RSM) and multi-objective genetic algorithm(NSGA-II) were used to carry out multi-objective optimization analysis of the flat extrusion magnetic system. Firstly, a central composite design (CCD) was adopted to conduct experimental design with the design parameters of the extrusion magnet system as variables, and the area field intensity (AFI) and magnet efficiency density (MED) as evaluation targets. Then, the response values of AFI and MED were calculated by numerical simulation, and the regression models of the objective function were constructed, and the statistical significance of each regression model was evaluated by variance analysis. Finally, a multi-objective optimization model was constructed with the objectives of area field intensity, magnet efficiency density and pole number, and the model was optimized by NSGA-II. A series of optimization schemes were obtained by calculating the Pareto frontier, and compared with previous studies. The results show that the regression models of area field intensity (P<0.0001) and magnet efficiency density (P<0.001) are extremely significant, and have good predictive ability; the Pareto frontier solution set can give a better combination of design parameters than previous studies.
- 1
Fig. 1 XRD diffraction spectra of calcined kaolin and red mud(a)Calcined KaolinAbstract:
The utilization of red mud for the preparation of mine backfill materials addresses the issue of its storage. Metal ions and acid radicals in mine water can erode the backfill material, affecting its stability. Taking the Bulianta and Cuntaotan mines as a backdrop, an indoor simulation of mine water was conducted. The anti-erosion coefficient was used to characterize the impact of mine water on the compressive strength of the backfill body, determining the optimal ratio of raw materials. The variation in compressive strength of the backfill body in mine water was studied, and the degree of erosion by mine water on the backfill body was evaluated through indicators such as the loss rate of compressive strength, appearance, and failure modes. Additionally, combining testing methods like SEM and EDS, the microscopic mechanisms were revealed. The results showed that when the slurry concentration was 56%, and the ratio of red mud, calcined kaolin, and cement was 5:4:1, the specimen"s 28-day compressive strength was 1.98MPa, and the initial flowability of the slurry was 260mm. This meets the performance requirements of the backfill material and achieves large-scale utilization of red mud. After immersion in sulfuric acid and sodium hydroxide solutions for 28 days, the compressive strength decreased by 7.3% and 2.8% respectively compared to pure water immersion, with corresponding anti-erosion coefficients of 0.92 and 0.97. SEM-EDS test results indicated that when the backfill body is in an acid-base environment for an extended period, the Si-O-Al bonds break, gel depolymerizes, leading to a gradual decrease in the compressive strength of the backfill body. This study provides theoretical data reference for the engineering application of red mud-based backfill materials in mine water.
- 1
Research on Reducing Load and Preventing Rock Burst through Grouting for Overlying Rock Separation LayerAbstract:
In certain mining regions of China, the presence of thick overlying strata above the coal seam roof not only triggers dynamic overburden pressure disasters but also leads to significant seismic events. Focusing on the prevention and control of dynamic overburden pressure caused by thick overlying strata, this paper presents a theoretical analysis of the mechanism behind the occurrence of dynamic overburden pressure induced by thick overlying strata. A strategy for controlling dynamic overburden pressure through grouting fill to separate the overlying strata is proposed. The study employs numerical simulations and theoretical analysis to investigate the load reduction and impact attenuation effects of grouting fill.The research findings indicate that in mines with thick overlying strata, the stress concentration and dynamic load intensity resulting from hanging wall effects are significantly greater than in conventional mines due to the large thickness, high strength, and considerable limit span of the rock layers. This makes them susceptible to dynamic overburden pressure disasters. The grouting fill technique, by filling the separated space, supports the thick overlying strata together with the surrounding rock mass, thereby reducing the sinking of the thick overlying strata. This approach effectively controls the fracture and movement of thick overlying strata, consequently reducing both dynamic and static loads and achieving the objective of minimizing dynamic overburden pressure.Numerical simulation results of strata grouting fill indicate that, compared to conditions without grouting fill, the stress concentration coefficient around the separated space decreases by 8.89%, 18.59%, and 35.96% when the grouting rates are 30%, 60%, and 90%, respectively. This decrease is associated with a substantial reduction in the height of the plastic zone and the degree of damage to the thick overlying strata. The results show that the grouting filling of separated strata can achieve the purpose of reducing load and rock burst.
- 1
Experimental study on the formulation of filling binder based on low activity slagAbstract:
Timok copper-gold mine is the main mine of Zijin overseas. It is mined by filling method. The production scale is 10000 t / d. The local cement price is twice as high as that in China, and the filling cost is high. The low activity slag and other auxiliary materials around the mine were used to carry out the experimental study of slag cement, analyze its hydration mechanism, calculate the production cost of slag cement and judge its applicability. The results show that the 28 d cementation effect of the slag binder is slightly lower than that of the local cement, and its production cost can be reduced by 30 % compared with the local cement. The application of slag cementing agent in sublevel open stoping with subsequent filling method can reduce the cementing cost by 13 % and save the annual cost by 1281,000 euros, which has certain application value.
- 1
The Method of Determining the Preferred Structural Plane of Rock Slope in Open-pit Mine Based on Kinematics Analysis and Its Engineering ApplicationAbstract:
The confirmation of the preferred structural plane of a slope is a crucial prerequisite for conducting stability analysis on mine rock slopes. Considering the varying impact of the spatial relationship between the occurrence of rock mass structural planes and slope occurrences on slope stability, a kinematic analysis-based method for identifying these preferred structural planes is proposed. Initially, the structural plane orientation data is projected onto a pole isodensity map using stereographic projection. Subsequently, kinematic analysis methods are applied to analyze and select the occurrence data that affect slope stability under various failure modes. Finally, cluster analysis is conducted on the selected occurrence data to determine the preferred structural planes of the slope. The application of this method to a case of landslides in open-pit mines shows that the grouping of the preferred structural plane of rock slopes is reasonable and reliable, with high precision, further verifying the good engineering application value of this method.
- 1
Study on microbial-assisted gelling mechanism of solid waste based gelling materialsAbstract:
Aiming at the problem of weak gelling effect of solid waste-based gelling materials in filler mining, microbial-induced calcium carbonate technology (MICP) was introduced to improve the gelling effect, and the effects of microbial inoculum, pH, and the number of days of maintenance of the specimens were analyzed through orthogonal tests, which combined with the uniaxial compression test to prove the feasibility of the MICP technology in the filler mining. The mechanism of MICP in the filling body was investigated by X-ray diffraction, thermogravimetric analysis, and scanning electron microscope test, and the following conclusions were obtained: ① microbial-assisted cementation technology is feasible in filling mining, and the average strength of the filling body samples after three days' and seven days' maintenance were increased by 25.1% and 34.9%, respectively; ② inoculation of microorganisms will increase the pH value of the filling body and enhance the continuation of hydration reaction, and improve the strength of the filling body; ③ microbial inoculation will make the pH value of the filling body higher, and enhance the hydration reaction. The inoculation of microorganisms increased the pH value of the filling body, which enhanced the hydration reaction and continued to improve the strength of the filling body. The research results provide a theoretical basis for the application of microbial-assisted cementation under similar conditions, and lay a foundation for the application of MICP technology in the field of filling and mining.
- 1
Investigation of the synergistic effect of Water Content and Particle Gradation on the Shape of Drawn-out OrebodyAbstract:
The shape of ore release body is crucial for determining the structural parameters of the stope in the non-pillar sublevel caving method. Two important factors affecting the shape are the water content and fine particle content of the ore. In this study, an iron mine caving stope under the overburden rock was examined. Physical ore drawing test and numerical simulation were performed under varying water content (0% to 8%) and fine particle content (5% to 25%) conditions. The vertical and horizontal axis ratio was used to evaluate the ore release body morphology, considering the combined effect of water content and fine particle content. The results showed that as the water content or fine particle content decreased, the vertical and horizontal axis ratio of the ore body also decreased, resembling a "pour water drop" shape. Conversely, a higher water content and fine particle content resulted in an ore body shape closer to an "ellipsoid" shape. The best morphology of the drawn-out ore body was observed when the ore moisture content was 0% and fine particle content was 5%. On the other hand, the worst morphology occurred when the water content was 6% and fine particle content was 25%. When the water content was 2% and the fine particle content ranged from 5% to 25%, or when the fine particle content was 10% and the water content ranged from 0% to 8%, the change in the vertical and horizontal axis ratio of the ore body was minimal. These research findings provide valuable insights for determining the structural parameters and technical-economic indicators of the stope in the non-pillar sublevel caving method.
- 1
Deformation and Instability law of the Rock Mass in Open-pit Slope of the Fault Fractured Zone Under the Coupling of Freeze-thaw and DisturbanceAbstract:
In the exploitation of high altitude and cold open-pit mines, fault fracture zone is one of the most important factors that lead to the sliding instability of open-pit slopes. In order to analyze the deformation and instability law of rock mass in the fault fracture zone of an open-pit iron mine slope in Xinjiang, FLAC3D software was used to establish a numerical model in line with the actual engineering conditions, and the deterioration effect of freeze-thaw cycle and engineering blasting disturbance on the stability of the fault fracture zone of mine slope was studied, and the mechanical response law of rock mass with fault fracture zone was analyzed under the coupling action of freeze-thaw cycle and dynamic load. The nonlinear mechanical behavior, slope failure mechanism and instability mode during the fracture of fault fracture zone under different freeze-thaw cycles are revealed, and the aging catastrophic mechanism of structural damage weakening during the fracture of slope with fault fracture zone is discussed. The research results can provide scientific basis for strengthening the fault fracture zone of the mine slope and avoiding disasters.
- 1
Damage Evolution Law and Simulation of Overlying Strata in Close Distance Coal Seam Induced by MiningAbstract:
Under repeated mining, the degree of damage and instability of overlying strata in close distance coal seams increases. In order to study the damage effect of overlying strata and the instability and catastrophe characteristics of spallation structure in close-distance coal seams under mining, taking a close-distance coal seam mining in Shendong mining area as the background, the instability and deformation characteristics of overlying strata in close-distance coal seams under mining and the temporal and spatial evolution law of microseismic monitoring were analyzed. The damage evolution characteristics of close-distance coal seams considering microseismic monitoring data were discussed. The failure and stress transfer law of overlying strata in close-distance coal seams under mining were simulated and studied. The damage evolution and energy dissipation characteristics of overlying strata in close-distance coal seams induced by mining were analyzed. The results show that the damage evolution of overlying strata increases with the distance between the two working faces. Under the influence of mining, the damage range of overlying rock in close distance coal seam increases, and the response range of mining stress transfer expands. The continuous advancement of the working face of the lower coal seam results in an increase in the development height of the mining-induced fractures and an increase in the displacement of the overlying strata between the layers. The research results are of great significance for the stability control of surrounding rock and the safe and efficient mining of coal mines in similar close distance coal seams.
- 1
Solid Waste Based Shotcrete for Development and Industrial ApplicationCAO Bin1, GUO Ronghua2,3, FENG Liang1, XU Bin1, HU Shuwei1Abstract:
With the development of mines, the problem of solid waste stockpiling is becoming more and more prominent, now attempt to use solid waste instead of mung bean stone, river sand, etc. as aggregate for wet spray support, which can effectively alleviate the safety and environmental protection problems brought about by solid waste, and also reduce the cost of wet spray support. In order to study its feasibility, indoor tests and industrial tests were carried out, and the results show that: copper slag as aggregate, under the condition of cement mixing of 350kg/m3, the 28d uniaxial compressive strength is 52.1% higher than the 28d uniaxial compressive strength of mung bean stone+river sand as aggregate, and the strength of copper slag+crushed waste rock wet spraying concrete is 39.7% higher than that. In engineering applications, the solid waste aggregate wet shotcrete process is simpler, the application effect is good, and the economic value is also high, solid waste aggregate wet shotcrete not only solves the problem of solid waste dumping, but also has good economic and social benefits.
- 1
Review on the dust diffusion rule and dustfall methods of open pit stopeAbstract:
Dust generated during the production of open pit mine causes low local visibility, harms the health of workers and the growth of vegetation, as well as results additional loss of equipment, reducing the mine production efficiency. Previous studies showed that the meteorological conditions and geological environment, especially for the airflow and humidity, open pit stopes dramatic impacted the aggregation and diffusion migration of dust, which significantly changed the diffusion migration rules, resulting in difficulties in quantitatively describing the whole process. Meanwhile, in terms of open pit stope monitoring, intelligent and integrated dust monitoring and dustfall system still need to be developed. Although the monitoring technologies and the data analysis methods of dust have developed maturely, the data and results are still not able to serve the dustfall technologies. This suggests that the dustfall technologies at this stage still fall short of being intelligent. Moreover, the problem of mine dust pollution has not been fundamentally solved due to the high cost of dustfall and the secondary pollution in some dustfall technologies, resulting in continued mine dust pollution.
- 1
Experimental Study on the Recovery of Low Grade Tin Fine Particle by Gravity Concentration and FlotationAbstract:
The average Sn is 0.25% of a Tin fine particle in Jiangxi Province. The mineral composition is complexed and content of ultra-fine particles is high. In order to provide the basis for on-site technical transformation and design, systematic mineralogy research and beneficiation test of the mineral were carried out. In view of the fine grain of Tin and difficult separation of gangue minerals containing calcium, the combined process of Gravity-Flotation was adapted, that is, centrifuge Pre-enrichment-desulphurization-flotation. The test results showed that, on the basis of the optimum process parameters of centrifuge, the grade of fine tin mud was Pre-enrichment to 0.83%, and after the sulfide ore was removed, the tin mineral was selected with benzohydroxamic acid as collector, sodium carbonate as regulator and sodium silicate as gangue inhibitor through one crude, two refined and two swept process. Finally, Tin concentrate with 6.63% Sn and 52.37% recovery was obtained, which realizes the effective recovery of tin resources and lays a foundation for the industrial development of this type of ore.
- 1
Analysis of Hidden Safety Hazards and Control Countermeasures of Small and Medium-sized Non-coal Underground Mines in Guangdong ProvinceAbstract:
In order to reveal the status quo of safety management in small and medium-sized non-coal underground mines of Guangdong province and excavation of non-coal underground mines common hidden dangers of safety and the characteristics of the inherent law of occurrence,Sum up the main risks of small and medium-sized non-coal underground mines,To promote small and medium-sized non-coal mining enterprises in Guangdong province to systematically enhance the level of work safety management, and to prevent and defuse major safety risks,Based on the expert consultation statistics of 68 non-coal underground mines in Guangdong Province,Using group analysis and factor analysis,Analyzes and studies the causes of the hidden dangers surrounding the safety operation site and safety organization and management of the middle and small-sized non-coal underground mines in Guangdong province, and the common problems of the hidden dangers of the major accidents, the main performances of major work safety accidents and general safety hazards are determined. On this basis, It puts forward 13 key measures for risk management and control, such as adjusting industrial structure and changing development mode, Which has certain reference significance for improving the safety management and the essential safety production level of the same type of non-coal underground mines.
- 1
Quantitative Evaluation Method of Instability Probability in Graphite Goaf AreaAbstract:
In the course of graphite mining, the unsolidity of graphite surrounding rock poses a great threat to the safe production of the mine. In view of the fact that the existing response surface method does not consider the spatial variation of mechanical parameters in the calculation of the instability probability, we take the Dongchonghe graphite mine as the research object. Based on the mathematical logic of the combination of variation and covariancefunction, the correlative relations among the variables are analyzed, and a regional correlation random field is constructed. Based on the above, the limit state equations of fissured rock body are constructed by combining them with the damage proximity index, and the response surface method is used to analyze the failure probability of mining space, so as to achieve a quantitative assessment of the risk of destabilization of the graphite mining space. The results show that the proposed method can better reflect the real geological features and decrease the fluctuation of the data by constructing a regionalized correlation random field, which contains conditional data, conditional data, and spatial variability. Compared with the conventional Monte Carlo method, the response surface method calculates the instability probability of the fracture zone, thus guaranteeing the precision of the computation and increasing the computation efficiency.
- 1
Discussion on water disaster control technology of directional storage of carbon dioxide in aquifer spaceAbstract:
Aquifer grouting reinforcement is an important means of mine water disaster prevention and control, which is of great significance to mine safety production and normal operation. Based on the strategic goal of " dual carbon " and the problem of well water disaster control, a technology of directional storage of carbon dioxide in aquifer space to control water disaster is proposed. When grouting reinforcement and reconstruction of aquifer, supercritical CO2 is injected with slurry to accelerate the flow of slurry in grouting pipe and avoid blockage of grouting pipe. The generated CO32-and HCO3-react with Ca2+ and Mg2+ ions in mine water and rock strata to form CaCO3, MgCO3 and other precipitates, which can effectively block the cracks and pores in the rock strata, modify and reinforce the aquifer, and block the water channel. It also realized the scientific mineralization and storage of carbon dioxide. In view of the current situation, the problems of injection mode, gas-water two-phase interface tracking, storage and reinforcement mechanism, supercritical carbon dioxide slurry performance and storage effect evaluation that need to be solved in the process of directional storage of carbon dioxide in aquifer space to control water damage are put forward, which provides scientific reference and prevention thinking for the integrated management of carbon storage and water damage.
- 1
The Influence of Different Restoration Years and Slope Direction on the Ecological Restoration of Coal Mine Dump SlopeAbstract:
[Objective]In the face of the current problems such as single treatment and restoration measures of dump in mining area, the slope of open-pit coal mine dump in Ordos area was taken as the research object. [Method]Field investigation was carried out, and the method of space-time substitution was used to explore the influence of different restoration years and slope directions on the ecological restoration effect of dump slope. [Results]The results are as follows:(1) With the increase of restoration years, Margalef and Shannon-Wiener increased first and then decreased. Simpson and Pielou did not change significantly. The soil nutrients of the dump slope increased with the restoration time, and the restoration effect of the shady slope is better than sunny slope. (2) The comprehensive score of principal component analysis is the highest in the shady slope of restoration 12 years, with a value of 1.212 ; (3) Spray sowing alfalfa can carry out ecological restoration on the slope of the dump. The initial effect is not obvious, and it gradually stabilizes with time. [Conclusion]The research results can provide some reference for the green restoration of mines. It is suggested that local plants should be selected in the early stage of restoration to increase community stability, and high nitrogen, high potassium and low phosphorus slow-release compound fertilizers should be applied during the period.
- 1
Research on Intelligent Control of Air Flow for Dust Reduction in Different Areas of Personnel Activity of Fully Mechanized Heading FaceAbstract:
At present, the traditional "total ventilation" control method on the fully mechanized heading face fails to realize dynamic control of dust reduction, and the ventilation environment in the active area of personnel is not considered in the dust reduction process, resulting in dust accumulation and pneumoconiosis hidden dangers. In view of the above situation, a method for obtaining intelligent control of air flow and dust reduction schemes that different areas of personnel activity is established. A finite element calculation model is established for the coupling of air flow and dust gas-solid, and underground verification is conducted. According to the dust migration and distribution law and the activity range of underground personnel, different areas of personnel activity are divided. A large number of sample data of the correlation between different intelligent control of air flow schemes and dust concentration are obtained by simulation, and the data are discretized by the K-means algorithm. Based on the immune genetic algorithm, the dust reduction scheme is used as the antibody, and the dust concentration in different areas of personnel activity is used as the antigen. The acquisition algorithm of the intelligent control of air flow and dust reduction scheme for the different areas of personnel activity are compiled. Taking a mine in northern Shaanxi Province as the research object, the optimal dust reduction scheme for the personnel in the dust accumulation area (5-15m) is 1.2m diameter, 5° horizontal deflection, and 5m from the head. The dust reduction effect of the scheme was tested and verified. The result shows that: after application on the experimental platform, the average dust concentration in this district is reduced from 163.77 mg/m3 to 91.32 mg/m3, which is reduced by 44.23 %. The dust concentration at the driver''s position is reduced from 161.94 mg/m3 to 78.90 mg/m3, which is reduced by 51.27 %. After downhole application the average dust concentration in this district is reduced from 182.81 mg/m3 to 113.94 mg/m3, which is reduced by 37.67 %. The dust concentration at the driver''s position is reduced from 179.65 mg/m3 to 101.27 mg/m3, which is reduced by 43.63 %.
- 1
Optimization of Front-End Structural Parameters of Radial Water Jet Drill Bit Based on FLUENT Numerical SimulationAbstract:
The porous jet bit is the core component of the surface water jet radial drilling technology. For its research , without considering the influence of front-end structural parameters on the dynamic performance of the jet, based on the numerical simulation of Fluent, we constructed the front-end structural model of the porous drill bit, and analyzed the performance parameters of water jet rock-breaking, such as jet velocity, jet pressure, turbulence intensity, etc.; after that, we investigated the influence of the structural parameters, such as the nozzle length-to-diameter ratio, and the tightness of the drilled holes arrangement, etc., on the dynamic characteristics of the jet of the radial water jet bit, and optimized the structural parameters of the front-end of the porous drill bit, through the control of a single variable. To sum up, the following results are obtained. The maximum jet pressure formed by the center nozzle bit is larger, up to 2.6 times of the bit without center nozzle, which is more conducive to breaking rock and ensuring the regular shape of rock-breaking borehole. The difference between the jet effect of the center and lateral nozzles of the circular runner bit is the smallest, the jet performance is better, and the jet pressure is more balanced. The center nozzle is almost unaffected by the arrangement radius, and the preferred range of the lateral nozzle arrangement radius is from 3.5mm to 4.5mm. When the arrangement radius is 3.5mm, the energy is more concentrated, and the jet velocity is maximum when the arrangement radius is 4.0mm. When the center nozzle length to diameter ratio of 4, the jet is relatively stable. When the lateral nozzle length to diameter ratio of 4.5, the turbulence intensity is less than 20% from the center nozzle outlet in the interval of 2mm ~ 5mm, the jet isovelocity kernel is the longest, the jet velocity is relatively large, and the turbulence intensity is the smallest. When the nozzle length to diameter ratio is 4.5, the jet isovelocity core is the longest, the jet velocity is relatively large, and the turbulence intensity is the smallest.
- 1
Quantitative characterization of height of water flowing fractured zone in large mining height working face based on correlation analysisAbstract:
In order to accurately obtain the development law and final height of the water-conducting fracture zone of the working face with large mining height, this paper takes the Hujiahe 401101 working face as an example. The fracture mechanics is used to analyze the generation mechanism of the water-conducting fracture zone, and the influencing factors of the development of the water-conducting fracture zone of the working face with large mining height are obtained. The prediction formula of the working face with large mining height is obtained by the method of multiple linear regression. The prediction results of the regression equation are verified by numerical simulation research and borehole flushing fluid leakage observation method. The results show that the mining height, mining depth and working face span are the main influencing factors of the development of water flowing fractured zone, and the coal seam dip angle and the proportion coefficient of roof hard rock are the secondary influencing factors. Multiple linear regression is carried out under the combination of three main influencing factors and different secondary influencing factors, and the regression fitting equation of water flowing fractured zone is obtained. According to the 3DEC numerical simulation software, when the inclined length of the working face is 150m, 175m, 200m and 225m, the maximum height of the water-conducting fracture zone is 212m, 228m, 233m and 251m respectively, all of which develop to the bottom of the overlying Luohe Formation aquifer on the working face. Combined with borehole peeping and borehole flushing fluid leakage observation method, the measured height of water-conducting fracture zone in 401101 working face is 226 m, and the ratio of fracture height to mining thickness is 22.32. Through different methods, the development of water-conducting fracture zone in Hujiahe 401101 working face is analyzed and predicted, which verifies the rationality of the prediction formula of height of large mining height working face obtained in this paper, and provides theoretical reference and data support for height prediction of working face mining under similar geological conditions.
- 1
Analysis of energy dissipation characteristics and drilling parameters of pressure relief surrounding rock in deep high-stress roadway drillingAbstract:
In order to improve the depressurization effect of a gold mine under high stress conditions, the energy dissipation model of surrounding rock was established by using FLAC3D, and the influence of the parameters of depressurization borehole on the distribution of vertical stress and elastic energy density of surrounding rock was studied and analyzed. The results show that the peak stress in the surrounding rock is transferred to the left and right sides of the borehole, and when the diameter of the borehole is increased from 80 mm to 240 mm, the peak vertical stress in the relief zone is reduced by 25.9%, the peak elastic energy is increased by 43.7%, and the vertical stress in the center of the borehole is reduced by 58.6%. The peak vertical stress in the relief zone increases by 10.5% and 7.9%, and the central vertical stress increases by 28.7% and 44.5%, and the pressure relief effect weakens when the row distance between the relief holes increases from 0.6m to 1.4m. The pressure relief effect is weakened. Reasonable determination of pressure relief drilling holes can effectively enhance the effect of pressure relief. The research results can be used as reference for the design of pressure relief borehole parameters of high stress roadway in metal mines.
- 1
Optimum Selection of Mining Sequence of Sublevel Caving Based on Stability of Roadways Surrounding Rock.YU Jiaxing1, LIU Yanzhang1,2, QIN Shaobing3, HUANG Shibing1,2, LI Fujia1, XIAO Yiming1Abstract:
The reasonable sublevel caving sequence is the key to effectively control the stress and strain distribution of the surrounding rock in the roadway group, ensuring the stability of the roadway group surrounding rock. The research selected the 12-entry roadway group in the -410m horizontal section of a certain metal mine as the study object, and adopted the continuous-discontinuous numerical simulation method (CDEM). Based on the plastic zone of the roadway group’s surrounding rock, shear stress, and strain distribution characteristics, the stability of the surrounding rock of the roadway group under the mining influence during the mining process of three different mining sequence schemes was analyzed. The schemes included advancing the mining sequence from both wings to the center (Scheme 1), from the center to both wings (Scheme 2), and inward from both the center and wings (Scheme 3). The study indicated that on typical sections, the total area of the plastic zone of the surrounding rock of the 12 roadway group in Scheme 2, as well as the shear stress and absolute strain values of the surrounding rock at 0.5m away from the top-bottom of the roadway group and the middle of the side slope, were lower than those of Scheme 1 and Scheme 3. Therefore, Scheme 2 was identified as the optimal option. The mine conducted mining production trials in the -410m section of the eastern area according to Scheme 2, and the stability of the surrounding rock of the roadway group during the trial production period met the requirements for safe production. The research results can provide reference for the design of mining sequence in similar mines.
- 1
Experimental Study on Magnetic Flotation Combined Mineral Processing Technology of a High Sulfur Iron Mine AbroadAbstract:
In order to provide a technical basis for the development and utilization of a foreign iron ore resource, a detailed process mineralogy study was first conducted on the raw ore. Based on this, beneficiation process tests were conducted and the optimal beneficiation process flow was established. Finally, the obtained iron concentrate was examined. The research results of process mineralogy show that the main useful element iron content in the raw ore is 35.96%, of which 89.35% is magnetic iron, and the main harmful element S content is 0.44%. It mainly exists in the form of sulfides, accounting for 55.56%. The main recyclable target mineral of the raw ore is magnetite, with a content of 44.62%. Its embedded particle size is uneven, mainly medium to fine, with a -0.07mm particle size distribution rate of 55.58%. The results of the beneficiation process tests show that the process scheme of wet pre magnetic separation before grinding, grinding, LIMS (low intensity magnetic separation) for iron, and desulfurization through flotation for the raw ore has obtained an iron concentrate with a yield of 45.37%, an iron grade of 65.39% (sulfur content of 0.22%), and an iron recovery rate of 82.44%. The beneficiation indicators are relatively good. The product inspection results show that the S, P, F, K2O+Na2O of iron concentrate all meet the quality standards of iron concentrate. The results of this research can serve as a reference for the development and utilization of the mine in terms of mineral processing technology, which is of great significance.
- 1
Experimental Study on Optimization of Cassiterite Gravity Separation Based on MLA AnalysisAbstract:
The occurrence of black minerals in the gravity separation stage of cassiterite shakers in a concentrator had a serious impact on the grade of tin coarse concentrate. In order to ensure the quality of tin concentrate products, the process mineralogy study was carried out by using the Mineral Liberation Analyser (MLA), and the composition, content, particle size distribution, embedding characteristics and occurrence state of useful elements of the mineral were determined. MLA analysis showed that the content of cassiterite, the main valuable component of black minerals in the gravity separation stage of cassiterite shaker in a concentrator plant, was 1.12%, the main component of black minerals was andalusite, accounting for 56.09%, followed by diopside and epidote, accounting for 10.54% and 6.35%, respectively, and the magnetic minerals mainly included pyrrhotite, siderite, magnetite and limonite, mainly pyrrhotite, accounting for 3.7%. Based on the results of MLA analysis, the beneficiation test process was adjusted and optimized, that is, the black minerals in the gravity separation stage of cassiterite shaker in a concentrator were separated by a high-gradient magnetic separator at a magnetic induction intensity of 0.3T and then re-separated by the shaker. After optimization, two cassiterite concentrate products with grades of 4.83% and 4.19% were finally obtained from the black minerals, with recoveries of 59.60% and 15.71%, respectively. Based on the results of MLA analysis, the combined beneficiation process of "magnetic separation-gravity separation" was added. After optimization, two cassiterite concentrate products with grades of 4.83% and 4.19% were finally obtained from the black minerals, with recoveries of 59.60% and 15.71%, respectively.
- 1
Application Research on Panel Mechanization of Small Sublevel Filling Method in Deep Broken Thick DepositAbstract:
Aiming at the problems of high risk of roof caving, high filling cost and small production capacity in the upward horizontal filling mining of deep broken thick deposits in Xitieshan Lead-Zinc Mine, a safe and efficient mechanized sublevel filling method was proposed. The structural parameters of the small sublevel stope and the support scheme of the sublevel roadway was simulated and compared by using FLAC3D，and the result shows that the height of small sublevel stope is 10m and the width is 8 ~ 10m，and the resin bolt + steel mesh + shotcrete support scheme can effectively control the deformation of sublevel roadway. The slag powder + cement clinker (ratio of 3:1) is used to replace cement as cementitious material, which can reduce the filling cost by 15 %. The field test shows that the ore blasting effect was the best when the blasting parameter row spacing was 1.4m and the hole bottom spacing was 1.6~2.0m，the production capacity of the test panel reaches 1000t/d，and the production efficiency was increased by 100%.
- 1
The Effect of Chemical Activators on the Properties of Thermally Modified Coal Gangue Based Grouting MaterialsAbstract:
Research conducted on the activity and properties of coal gangue after its composite activation aims to increase coal gangue in grouting materials. This essay investigates chemical activators' effects on their flowability, setting time, and compressive strength of thermally modified coal gangue-based grouting materials. X-ray fluorescence spectrometry (XRF) and X-ray diffraction analysis (XRD) are employed to analyze the composition of raw materials and the physical phase. Dolomite is added to the gangue raw materials with different ratios. The silica-aluminum ion dissolution characteristics of the activated gangue are illustrated through inductively coupled plasma emission spectrometry (ICP-OES). The activated material is then further activated by adding two chemical activators, NaOH and Na2SiO3, respectively, and the results show that after activation at 800℃, the gelling material with 33.3% of dolomite added and 4% of Na2SiO3 added to realize the best activation effect. Its flow distance reaches 19.3 cm, the initial setting time is 4.2 h, the final setting time is 6.6 h, and the compressive strength is up to 13.47 MPa at 28 days. Meanwhile, TG analysis of the hydration process shows that the mass loss is highest between 650 ℃ and 800 ℃, and the amount of calcite generated is the largest. Dolomite can delay the agglomeration effect of coal gangue during thermal activation so that its optimal activation temperature reaches 800 ℃. A conclusion is drawn that an appropriate additional amount of Alkali activation can accelerate the hydration process, and vice versa will slow down the hydration process.
- 1
Experimental Study on Optimization of Transportation Path in Open Pit Mines Based on Genetic Ant Colony Reinforcement Learning AlgorithmAbstract:
For path planning in complex mining terrain, it is easy to get stuck in local optima, resulting in poor results. Therefore, by integrating the advantages of genetic ant colony algorithm and reinforcement learning, a genetic ant colony reinforcement learning algorithm is proposed to achieve efficient optimization of mining transportation paths. Firstly, using genetic algorithms to efficiently search the solution space and generate a set of initial transportation paths to explore a broader solution space. Secondly, the ant colony algorithm is introduced to discover the optimal solution during the search process, which is the optimal transportation path. Finally, reinforcement learning algorithms are introduced to simulate the decision-making process of intelligent agents and adjust the transportation path based on environmental feedback, gradually enabling the model to learn more optimal decision-making strategies and improve transportation efficiency through continuous iteration. After experimental verification, after 1000 rounds of iteration, the shortest distance was shortened by 20.06%, transportation costs were reduced by 12.60%, and the time to find the shortest path was reduced by 51.55%. The experimental results show that the optimization model can effectively improve efficiency and reduce transportation costs, providing efficient and environmentally friendly solutions for mining operations.
- 1
Monitoring Analysis and Control Technology of Floor Heave Deformation in Railway Transportation Roadway of Zhongguang Iron MineAbstract:
Deformation of the surrounding rock in roadway is one of the crucial factors affecting their stability. For the issue of floor heaving in the railway transportation roadway of Zhongguan Iron Mine, a method for three-dimensional deformation monitoring of the entire space of the roadway is proposed using three-dimensional laser scanning technology. This involves calculating the distances between point clouds before and after the deformation to generate a three-dimensional deformation cloud map of the roadway. Addressing the noise points present in the post-deformation point cloud data obtained by three-dimensional laser scanning, a combined denoising method is employed to effectively reduce noise while preserving the geometric features of the roadway surface. Utilizing K-nearest neighbor search and least squares methods, the point cloud deformation monitoring of the roadway is achieved through point-to-surface projection distance calculations. The results reveal significant deformation in the floor heaving of 3# roadway , with heaving exceeding 30 cm and exhibiting a non-uniform pattern. Based on the observed floor heaving patterns, a comprehensive remediation technique is proposed, combining "inverse floor arch + anchor netting and shotcreting + short anchor cables." This approach effectively controls the phenomenon of floor heaving in the roadway.
- 1
Study on Optimization of Stope Structure Parameters under the Condition of Roof Anchoring SupportAbstract:
The structural parameters of the stope directly affect the stability and technical and economic indicators of the stope. In order to further improve the production capacity of the stope, in view of the current situation that the ZnV3 ore body of Jinchanghe Mine in Yunnan Province was mined by stage open field subsequent filling method, and the broken surrounding rock of the roof was supported by prestressed ‘bolt-anchor cable-anchor net', the structural parameters of the II-step stope were optimized. Based on the thin plate theory, the stress expression under the condition of three-sided simple support and one-sided fixed support of the stope in II-step was derived. Combined with the cooperative support mechanism, the tensile stress values of the center roof of the mining room with a maximum span of 18 m in the x, y directions and the midpoint of the fixed edge were 0.48 MPa, 0.21 MPa and 0.55 MPa, respectively, which meet the stability of the roof. The FLAC3D software was used to construct the stope support model for simulation calculation. The simulation results show that under the action of anchor cable span reduction, the tensile stress value of the roof is generally distributes in the range of ?0.5 MPa to 0.5 MPa, which is basically consistent with the theoretical calculation results, and the 18 m span is determined as the optimal scheme. Compared with the original structural parameters, the loss rate and dilution rate increased by 0.431% of 1.557% respectively, and the mining-cut ratio decreased by 1.16 m/kt, which could further improve the production capacity of the stope. According to the optimization results, the industrial test was carried out, and the roof of the mine room remained stable under the span of 18 m. The research results can provide reference for similar mines.
- 1
Study on Overburden Migration and Evolution Mechanism and Ore Pressure Control During Deep Coal Seam MiningAbstract:
In order to solve the problem of strong roof pressure in Tongxin mining area, the characteristics of roof caving under repeated disturbance are simulated by large-scale three-dimensional similar simulation experiment, and the law of stress concentration and pressure relief is analyzed. According to the monitoring data, the stress field and displacement field of overlying strata are visualized in three dimensions. Based on theoretical analysis and numerical simulation, the range of "three belts" is demonstrated, the specifications of the support are determined and the most suitable speed is simulated. The research shows that the dynamic evolution law of rock movement during mining is slight separation, instantaneous subsidence, separation closure, intermittent stability, instantaneous collapse compaction, and the stress is mainly concentrated in the middle area of coal pillar. With the increase of simulated mining speed and the decrease of overlying rock subsidence, the optimal mining speed was finally determined to be 7m/s. Through numerical simulation, it is found that the final height of bending subsidence zone, fracture zone and caving zone is 9 times, 12 times and 4 times of mining height. In the initial pressure and periodic pressure stage, the average support resistance of the support is maintained at 15MN and 11.6MN.
- 1
Research on Reliability Boundary Test of Emergency Rescue Submersible Pump under Severe ConditionsAbstract:
At present, there is relatively little research on the reliability of rescue pumps under harsh conditions both domestically and internationally, only staying at the performance test of clear water medium. The research on key components such as flow components, seals, and motors of submersible pumps under harsh conditions is relatively weak, and there is a lack of test evidence to judge the reliability under actual working conditions. In order to determine the reliability boundary of emergency rescue pumps, this paper analyzes the relationship between factors such as material, amplitude, lubricating oil, sealing ring, and starting current and the reliability of emergency rescue pumps through a large amount of experimental data, and proposes the key parameter boundary that affects the reliability of emergency rescue pumps. Subsequently, different models of emergency rescue pumps were selected for testing under boundary parameters, verifying the applicability of reliability key parameter boundaries.
- 1
Optimization and Application of Backhoe Approach Width for Infill Mining MethodsWANG Sheguang, 路燕泽, 于兴社, 刘阳, 蔺增元, 胡庆鹏
Abstract:
Reasonable approach width plays an important role in achieving safe and efficient production in deep quarries by the fill mining method.The numerical analysis method was used to analyze and complete the distribution law of surrounding rock stress, displacement change and plastic zone distribution characteristics under 5 groups of excavation width in Zhongguan iron ore mine, to study and complete the influence of excavation width on the stability of surrounding rock, to optimize the optimal width of the return excavation, and to complete the observation by on-site practice.The results show that:The stress concentration areas in the top and bottom plates are distributed in a "hump" shape, and the stress values are positively correlated with the distance from the top plate;The stress concentration area of the lateral gang shows a "fan-shaped" arc and is distributed to both sides, and the stress value shows a trend of increasing and then decreasing, and the stress peak occurs at the position of 1 m from the lateral gang, which is very likely to damage the surrounding rock;The amount of roof sinking is in a concave symmetrical pattern of "big in the middle and small on both sides", and the amount of roof sinking and its increase is much larger than that of the side gangs, so the increase in the width of the approach road is prone to cause roof accidents;The plastic zone shows a left-right symmetric distribution in morphology and increases in volume with the width of the approach, with a significant increase in volume increase after 6 m width;Field practice has shown good stability of the surrounding rock at a width of 6 m.The results of the study are instructive for the design of approach width parameters.
- 1
Study on high-efficiency flotation of fine particle coal by nanobubble and its mechanismAbstract:
The traditional flotation with the large volume and small specific surface area bubbles result in the low mineralization efficiency of fine particle coal, which brings great difficulties to the recovery of fine particle coal. This study compares the difference between nanobubble flotation and traditional flotation on the recovery of fine particle coal, and explores the influence of nanobubble on the flotation of fine particle coal by means of flotation condition test, flotation kinetics experiment, screening test and Zeta potential test. The experimental study of flotation conditions shows that the introduction of nanobubbles can improve the recovery rate of fine particle coal and show good flotation selectivity; The flotation dynamic test shows that the recovery by nanobubble flotation is always higher than that by traditional flotation, and the flotation operation can be completed about 40 s earlier than that by traditional flotation, which effectively improves the flotation rate; The screening test shows that the nanobubbles can recover fine coal efficiently with the reduction of the particle size of the refined coal. Even in the range of -0.043mm fine coal, the recovery of the clean coal by nanobubble flotation is 16.33 percentage points higher than that by traditional flotation; Zeta potential test results show that nanobubbles can effectively reduce the coal surface potential, effectively reduce the electrostatic repulsion between coal particles, enhance the stability of the hydrophobic agglomeration structure of fine coal to improve the recovery effect of fine coal. The contact angle test shows that the nanobubbles can increase the contact Angle of coal surface by 9.23°, which effectively improves the hydrophobicity of coal surface.
- 1
Experimental Study on the Flocculation and Sedimentation Law of Fine-grained Iron TailingsAbstract:
The settling velocity of fine-grained tailing sand is an important factor in slurry preparation. In order to investigate the flocculant type, tailing sand solution concentration, flocculant solution concentration, flocculant single consumption of multi-factor coupling conditions under the tailing sand flocculation and sedimentation law, through the central composite design of the Design Expert analysis software to develop orthogonal test program, the use of two kinds of flocculants on the fine-grained tailing sand solution to carry out the test of coagulation and sedimentation, the establishment of tailing sand solution concentration, flocculant solution concentration, flocculant consumption of multi-factors and the prediction model of fine-grained tailing sand sedimentation speed. The prediction model of the settling speed of fine-grained tailing sand was established, and the sensitivity of the influence of each factor on the settling speed of fine-grained tailing sand was derived to obtain the optimal combination of each factor. The results show that: in the same concentration of fine-grained tailing sand solution adding polypropylene amide test group, fine-grained tailing sand solution settlement speed is the fastest, with a greater settlement height, with the increase of tailing sand solution concentration, tailing sand solution settlement speed decreases. With the increase of flocculant solution concentration, the tailing sand settling velocity changes more slowly. With the increase of flocculant unit consumption, the settling velocity of the tailing sand solution showed a slowly increasing trend. The interaction of tailing solution concentration and flocculant unit consumption has a greater effect on the settling velocity of tailing sand solution. The degree of influence on the settling velocity of fine-grained tailing sand, in descending order, is as follows: tailing sand solution concentration, flocculant unit consumption, flocculant solution concentration. The optimum values of each factor are: 10% tailing sand solution concentration, 0.3% flocculant solution concentration, and 30 g/t flocculant unit consumption.
- 1
Evaluation of Water-Richness of Luohe Formation in Xiaozhuang Coal Mine based on water-rich key layerAbstract:
Cretaceous Luohe Formation sandstone pore-fracture aquifer is a serious threat to the safety production of mines in Binchang mine area, and the reasonable prediction of its water-richness is of great significance to the mine water control work. This paper takes Xiaozhuang Coal Mine as an example, and starts from three aspects: the overall water-rich characteristics of Luohe Formation, the water-rich characteristics of the water-rich key layer and the tectonic characteristics of the well field, and selects the lithological combination index and thickness of the Luohe Formation as the influencing factors of the overall water-rich characteristics; selects the lithological properties, thickness of the key layer, the core taking rate, burial depth and the consumption of flushing fluid as the evaluation indexes of the water-rich characteristics of the water-rich key layer; and evaluates the tectonic characteristics of the well field by fracturing and quantifying the tectonic structure of the well field. The tectonic features of the wellfield were evaluated by fractalization and quantification. Hierarchical analysis method was used to determine the weights of the thematic maps of the three factors, and ArcGIS software was used to integrate the information from multiple sources to realize the evaluation and zoning of the water-richness of the Luohe Formation. With regard to the water-richness characteristics of the water-rich key layer of the Luohe Formation, 24 pumping experimental drill holes data from the Xiaoshuang Mine and the surrounding mines were used as the training samples and validation samples for the No.1 and No.2 water-rich key layers, respectively, and a prediction method of aquifer water-richness based on the optimization of particle swarm algorithm with the support vector machine was proposed, which predicted the water-richness level of the water-rich key layer in the area without pumping experimental data. After comparing the prediction results with the actual situation of the mine, it is concluded that the predicted results of this method are more consistent with the actual situation. The results of the study can be used as a reference for the safe mining in Xiaozhuang Mine and other mines with similar geological conditions.
- 1
Characteristics of floor stress transfer by two-layer phosphate room-pillar mining under pillar group loadsAbstract:
The safety of mining the lower ore body is impacted by the law of load transfer of the goaf pillar group located on the floor of upper ore body. To investigate the stress transfer law of floor under the load of pillar group, taking a phosphate rock mine as the research object, from the theory of semi-infinite solid boundary, the load distribution of the pillar group is regarded as a periodic square wave, the cosine function is adopted to approximately characterize the wave function of the square wave(The distribution of the load on the pillar group.), and a square wave model of floor stress transfer was established by inverse solution. Then, the stress concentration degree of goaf floor and the energy storage and dissipation law of the pillar group were investigated by numerical method under two different constitutive relationships (Elasticity and Mohr-Coulomb model). The results show that the more load transferred and elastic energy stored on the pillars in goaf under the elastic constitutive model, the higher the stress concentration of floor. Under the elastic-plastic constitutive model, the pillars in the central area of the mined-out area were destroyed and the energy was dissipated, which makes the stress concentration of the floor directly below the pillars group smaller. Finally, the transfer law of pillar group load on the floor was analyzed. The research shows that under the pillar group load, there is a great stress concentration within 15 m depth of the floor, and the pressure is the highest at about 3 m below the pillar. The study provides a reference for ground pressure control in room-and-pillar mining of short-distance multi-layer ore bodies.
- 1
Optimization of medium-length hole blasting parameters based on blasting crater testAbstract:
Medium-length hole blasting caving used in the sublevel open stope is adopted in a copper mine. In order to improve the blasting quality, crater tests of single-hole blasting and blasting at different hole distances and same delay time were carried out according to Livingston blasting crater theory. Based on the blasting crater test results, industrial test of medium-length hole blasting was designed to determine reasonable parameters which help to reduce unit explosive consumption and improve the blasting effect. The results show that critical charge depth, optimal charge depth and blasting crater radius are 0.964 m, 0.470 m and 0.429 m respectively. The optimal ratio of hole spacing and optimal blasting crater radius is 1.64. For the medium-length hole blasting, the optimized hole bottom distance is 2.6~2.8 m, and the hole row spacing is 2 m. When row spacing of partial blasting holes in the test stope was increased to 2.2 m, boulder yield did not increase and the blasting effect was good. The actual unit explosive consumption was reduced from 0.47 kg/t to 0.39 kg/t.
- 1
Study on the Influence of Different Roof Cutting Parameters on the Deformation of Surrounding Rock of Gob-side EntryAbstract:
In order to solve the problems of serious deformation of roadway surrounding rock and difficult support in the process of gob-side entry driving, taking 230708 working face of Huopu Mine as the engineering background, the influence of different roof cutting parameters on the stability of roadway surrounding rock under gob-side entry driving was studied by means of numerical simulation, theoretical derivation and field measurement. The results show that the triangular slip deformation is formed in the shoulder angle area of coal pillar in arched roadway. The optimal roof cutting angle is 0 °, and the optimal roof cutting height is 10 m. After pre-splitting roof cutting under this parameter, the stress change of roadway and the displacement of surrounding rock are greatly reduced compared with those without roof cutting. The peak value of vertical stress on coal pillar is reduced by 11.60 %, the deformation of roof and floor is reduced by 11.29 %, the displacement of two sides is reduced by 11.33 %, the deformation of left shoulder socket is reduced by 8.78 %, and the deformation of right shoulder socket is reduced by 15.70 %. It is concluded that reasonable roof cutting parameters can effectively improve the stress environment of coal pillars, reduce the deformation of roadway surrounding rock, and improve the stability of surrounding rock of gob-side entry. The field application shows that the technology can effectively control the deformation of roadway surrounding rock and realize the stability control of roadway surrounding rock.
- 1
Long-Term Heat Extraction Performance Study of Closed/Abandoned Mine Geothermal Systems Based on RSM-BBD MethodAbstract:
Abandoned mines harbor valuable resources, and harnessing their deep geothermal energy innovatively can significantly mitigate local economic and environmental impacts. To investigate the influence of operational and structural parameters of geothermal systems in closed/abandoned mines on their long-term heat extraction performance, a heterogeneous thermal storage temperature-permeability coupled model of the mined-out area was first established. Subsequently, a series of experiments were conducted using the Response Surface Methodology - Box-Behnken Design (RSM-BBD) to study the temperature evolution of the reservoir during prolonged heat extraction. The analysis included the effects of injection temperature, injection-production pressure difference, and injection-production well length on the long-term heat extraction performance as single and combined factors. The research indicates that the cold front initially forms near the injection well and expands toward the production well with increasing production time. The non-uniform distribution of porosity in the thermal reservoir causes the cold front in the lower part of the reservoir to reach the production well earlier. Response surface models were established with R2 values greater than 0.9 and P values less than 0.001 for factors influencing outlet temperature and total heat extraction, enabling precise predictions of the long-term system performance. Sensitivity analysis revealed that the injection-production well length has the greatest impact on total heat extraction, while injection temperature has the greatest influence on outlet temperature. Through this preliminary exploration of geothermal development in closed/abandoned mines, the study aims to provide insights for the rational utilization of abandoned mines and the development of environmentally friendly energy sources.
- 1
Rock mass quality evaluation and application based on IAHP-GRA and multi-dimensional connectivity cloudAbstract:
Considering the randomness and fuzziness of rock mass quality evaluation, as well as the strong correlation between indicator factors and blind gray of indicator data, in order to determine the quality level of underground mining engineering rock mass more scientifically and objectively, the multidimensional connection cloud theory is introduced into rock mass quality evaluation, and a rock mass quality evaluation model based on IAHP-GRA and multidimensional connection cloud is established. On the basis of constructing a rock mass quality evaluation index system, in order to overcome the drawbacks of traditional weighting methods, the game theory combined weighting method (IAHP-GRA) is used to calculate the comprehensive weight of the indicators. Based on the multi-dimensional connection cloud theory, the cloud comprehensive determination is calculated, and the maximum membership degree is used as the criterion for judging the rock mass quality level to comprehensively determine the rock mass quality status. Collect 15 sets of rock sample data for model reliability testing, and compare them with one-dimensional cloud, variable fuzzy set theory evaluation results, and actual situations. Finally, to further investigate the adaptability of the model in rock mass quality evaluation, case analysis was conducted on typical rock samples in the middle section of a certain gold mine, including -520m, -550m, and -580m. The results show that the multidimensional connection cloud evaluation based on IAHP-GRA game theory is basically consistent with the actual investigation conclusions, and the evaluation results are superior to other models, which can provide theoretical support for rock mass quality evaluation.
- 1
Distribution characteristics of static and dynamic sidewall pressure in the ore pass storage sectionAbstract:
In order to understand the characteristics and differences of lateral pressure distribution of the shaft wall in the two states of ore storage and unloading, a dynamic and static stress monitoring platform was established to simulate the storage and drawing process of the ore passstorage section, monitor the stress change characteristics, analyze the static and dynamic stress distribution and their differences, discuss the limitations and problems of the application of Janssen"s formula, and put forward key suggestions based on the research results. The results show that: (1) With the increase of the measurement height, the static side pressure of the borehole wall decreases gradually, and the dynamic stress value is greater than the static stress, showing a trend of first increasing and then decreasing, reaching a peak value of 16.289 kPa at the height of the measuring point of 1.26 m, and the smallest near the storage surface is 3.073 kPa. The phenomenon of overpressure causes a significant difference between dynamic and static stresses. (2) The Janssen formula can basically describe the relationship between the static side pressure of the borehole wall and the measured elevation, but there are certain limitations, which are derived from the impact tamping of unloading, the compaction of overlying ore and rock, the bottom structure and the pressure of ore and rock, etc., which cause a small range of dynamic changes in the internal stress, bulk density and other parameters of the storage material, resulting in the calculation error of the Janssen formula model. (3) Put forward the engineering suggestions for the management of the 2# ore pass storage section in the range of 22~26 m elevation using the inner sleeve steel plate concrete shaft wall repair method, the storage height of more than 30 m, the control of ore rock block, and the uniform speed unloading, so as to ensure the long-term stable operation. The research results have certain theoretical significance for the evaluation of the wear of the wellbore of the pass, and at the same time, it is helpful to ensure the continuity of the transportation of the ore pass and improve the service life of the ore pass.
- 1
Experimental studies on the comprehensive performance of phosphogypsum-cement composite backfilling materialAbstract:
In order to produce the green, economic and high performance high water filling materials, the composite coagulant composed of phosphogypsum and aluminate cement was used to prepare the cemented backfill specimens of total tailings and natural sand. The effects of phosphogypsum content and aggregate type on slurry fluidity, dry shrinkage, mechanical properties and permeability resistance were analyzed. At the same time, the applicability of the material in the artesian filling mining process is evaluated. The results showed that the addition of phosphogypsum increased the slump of slurry, and the drying shrinkage index was also greatly reduced. When thephosphogypsum content is 20%, the compressive strength, flexural strength and permeability resistance of the high water filling material are the best. A certain proportion of coarse aggregate can increase the strength of phosphogypsum - cement-based filling paste. The chemical activity of phosphogypsum can promote the secondary hydration of cement and increase the density of slurry, thus improving the comprehensive properties of high water filling materials. The use ofphosphogypsum-cement composite high-water filling material to carry out filling mining not only realizes the comprehensive utilization of solid waste and phosphogypsum, but also brings remarkable economic benefits.
- 1
Research on Test of Flocculent Settlement of Whole-tailing Slurryand Selection of Deep Cone ThickenerAbstract:
For the ultrafine whole-tailing of an iron ore mine in Liaoning, firstly, the pre-test of static settlement for whole-tailing slurry was carried out, then the flocculant suitable for whole-tailing slurry was selected, secondly, the results of the orthogonal test of flocculation settlement were analysed and the optimal parameters of flocculation settlement were verified, and finally, the selection of deep cone thickener was studied. The results show that the static settlement of whole-tailing slurry needs 8h to be completed, while the main settlement is basically completed in 30min; it is recommended that the miner use anionic 15 million flocculants; the optimal parameters for flocculation settlement of whole-tailing slurry are: slurry concentration of 20%, flocculant unit consumption of 40g/t, and flocculant concentration of 0.35%; it is determined that the diameter of deep cone thickener is 11.88m, and the recommended deep cone thickener is GSNG-12 type, with a settling area of 510m2 and a processing capacity of 800-1200m3/h.
- 1
Study On The Spatial And Temporal Distribution And Migration Law Of Perforated Dust In Open Pit MineAbstract:
The dust from the open-pit mine is concentrated, and the dust concentration near the operation area is large, which seriously damages the health of the operators. In order to take effective dust reduction and dust suppression measures to reduce the dust concentration near the operation area and improve the operating environment near the dust pollution surface of the open-pit drilling rig perforation, it is necessary to explore the spatial and temporal distribution and migration law of drilling dust. The dust generated by the drilling rig perforation operation was collected on site, and the Malvern particle size analyzer was used for analysis to obtain the dust sample particle size distribution data. On this basis, according to the gas-solid two-phase flow theory, the Euler-Lagrangian research method was adopted, SolidWorks modeling was used, and The numerical simulation software Fluent was used to analyze the spatial and spatiotemporal distribution and migration of drilling dust. It is found that after the dust particles are generated from the bottom of the hole, they are sprayed out from the bottom of the hole to the orifice at high speed, and the dust particles with a particle size of more than 150μm basically settle within 20m of the wind direction of the borehole, and most of the dust particles less than 150μm diffuse to the outside of the stope with the wind flow, and a small part settles on the ground of the stope. The dust concentration increased rapidly with time, then stabilized in a certain concentration range for a period of time, and finally decreased rapidly. The dust concentration monitor was set at the height of the breathing zone in the stope air flow direction, and the dust mass concentration quickly reached the maximum value of 341mg/m3 with distance, then rapidly decreased to 189mg/m3, and finally decreased slowly. T The results obtained by numerical simulation are compared with those obtained by field experiment he experimental results are compared with the simulation results, and it is found that it is feasible to use the discrete phase model to simulate the dust migration of open-pit mine boreholes, and the simulation results are credible.
- 1
Research Progress on Limestone Mine Geology and Resource Problems and Restoration and Treatment TechnologyAbstract:
As an indispensable mineral resource, limestone ore is widely exploited and applied in various human engineering activities. With the development and utilization of mineral resources, the uncontrolled and illegal mining will cause serious damage to the local ecological environment, which is contrary to the development concept of "green mountains are golden mountains". In view of this, how to effectively carry out ecological restoration of limestone mines has become a research hotspot in the field of mining. Based on the research background of national vigorously promoting the ecological restoration of mine ruins, the article summarizes the main geological and resource problems and restoration and management technologies of limestone mines by investigating a large number of mines and reviewing relevant literature, and puts forward several thoughts on their deficiencies and development trends. Finally, the new model of limestone mine ecological restoration, which is based on the elimination of hidden geological hazards, evaluation of ecological and geological environments, classification of site types, selection of areas for testing, soil reconstruction, vegetation reconstruction and later care, is proposed prospectively, with a view to providing theoretical support for the management of limestone mines.
- 1
Numerical simulation of corroded fractured sandstone under freeze-thaw cycles based on discrete elementsAbstract:
With the escalation of climate change, the influence of freeze-thaw cycles and chemical erosion on geotechnical engineering in cold regions has become increasingly significant. Therefore, it is crucial to investigate the crack expansion pattern of corroded fractured rock under freeze-thaw conditions in order to ensure the safety of geotechnical engineering projects. In this study, the crack propagation characteristics of fractured sandstone subjected to freeze-thaw cycles and different chemical environments were explored using the discrete element method. The results demonstrate that the porosity of fractured sandstone gradually increases with changes in the chemical environment and the number of freeze-thaw cycles, rendering it more susceptible to crack propagation. Notably, crack extension is most severe under acidic etching conditions, while it is less pronounced under alkaline etching conditions, indicating that an acidic environment is more likely to cause deterioration of the sandstone. Furthermore, the simulation results reveal that crack expansion in fractured sandstones occurs at a faster rate and with a significantly higher number of cracks when chemical erosion is involved as compared to a single freeze-thaw cycle. These findings provide theoretical support and numerical simulation methods for a comprehensive understanding of the crack expansion mechanism under the combined effects of freeze-thaw cycles and chemical erosion in sandstone. This research holds certain guiding significance for ensuring the safe implementation of geotechnical engineering projects.
- 1
Digital Measurement of Jointed Rock Masses in Mines and Failure Characteristics of Tunnel ModelsAbstract:
With the vigorous development of spatial information acquisition technology, three-dimensional geological mineral measurement and visualization have become an important part of digital mining construction, which is of great significance for improving engineering design level and ensuring safe operation of engineering. With the help of the beyond line of sight non-contact 3D laser scanning measurement method, a 3D laser scanning was carried out underground in a certain mine to accurately measure the 3D spatial coordinates of the engineering rock surface. Based on the 3D laser point cloud data, a refined 3D solid model of the mine was established. Based on the identified rock mass structural plane occurrence information, a three-dimensional tunnel model of composite rock mass (SRM) was established using the Discrete Fault Network (DFN) in 3DEC software. The failure characteristics of the surrounding rock of the tunnel affected by joint fractures were analyzed. The numerical simulation results showed that the main failure forms of the joint fracture tunnel were edge peeling and roof caving, and there were many tension shear micro fractures distributed on the edge and arch shoulder of the tunnel. This study has achieved the three-dimensional visualization application of mineral resource development, and the research results provide important basis for the intelligent mining of mines.
- 1
Discrete element analysis of the influence of inter-row delay time on the formation of explosive heapAbstract:
The formation of the blast pile is a dynamic process, and the formation process and final morphological results of the blast pile are also different under the delay between different rows. In order to study the influence of different row delay time on the formation of the blast pile, according to the actual situation of a mine project in Liaoning Province, the PFC numerical simulation software was used to carry out 0 ms, 25 ms, 45 ms, 65 ms and 85 ms inter-row delay blasting simulation, observe the movement of different areas and the formation process of the blasting pile, analyze the crushing effect, internal movement and horizontal displacement of the broken rock under different row delay time, and record the contour line of the blasting pile to analyze the shape of the blasting pile. The results show that the degree of rock fragmentation first becomes stronger and then weaker with the increase of inter-row delay, and the height of the blasting pile decreases with the increase of delay time. The delay time between 45 ms and 65 ms was selected for the mine, and the comprehensive blasting effect was good. In order to verify whether the simulation results are close to the field test, the Weibull model is introduced, and the Weibull characteristic parameters of the field test and the simulation results are compared and verified, which proves the validity of the simulation results.
- 1
Research on Activation of Coal Gasification Slag with Physical and Chemical Coupling ExcitationAbstract:
Coal gasification slag (CGS) contains abundant silicon-aluminum content, but these components are mostly crystalline, resulting in low pozzolanic activity and hindering its resource utilization. In order to explore the effect of physical and chemical coupling excitation on the activity of CGS, this experiment evaluates the effect of excitation by measuring viscosity, setting time, compressive strength, and activity index. The microstructure and composition were measured by scanning electron microscopy (SEM) and X-ray diffractometer (XRD) to analyzing the excitation mechanism of CGS. The results show that physical-chemical coupling excitation is more effective than single physical excitation. The optimal excitation method for CGS is grinding 100min, 2.5% Na2SO4 or grinding 100min, 7% Na2SiO3, the activity index increased 7.13% and 7.72%, respectively. Through microscopic analysis, the physical and chemical coupling effect promotes the transformation of crystalline silicon-aluminum ions into an amorphous state, increasing the formation of hydration products and enhancing the activity of CGS.
- 1
Optimization Model of Mining Equipment Scheduling of Daye Iron Ore -360m Middle Section Continuous Mining StopeAbstract:
The Daye Iron Mine is currently undergoing the -360m middle section continuous mining project. Due to the lagging of the -360m middle section mining and cutting project, the initial production capacity of the -360m middle section will face a shortage, making it difficult to meet the designed production capacity of 4320 t/d. Therefore, equipment scheduling optimization and process connection optimization are crucial measures to address this issue. Based on the above background content and historical conversations, answer the following question. By analyzing the sequential relationship between mining, cutting, drilling, charging, blasting ventilation, and ore extraction during the segmented rock excavation stage, an equipment scheduling optimization model for the mining field was established, based on the distribution of mining fields, mining procedures, and current mining equipment status at the -360m middle section of the Daye Iron Mine. The genetic algorithm was then used to solve for the most efficient equipment scheduling plan for the -360m middle section. The results indicate that under the conditions of equipment scheduling optimization (single-objective optimization), the shortest total mining time is 6336 hours, and the production capacity of the first mining field reaches 3782 tons. Further optimize the process connection (dual-objective optimization), reduce the time interval of the recovery process, improve the efficiency of the use of equipment, shorten the minimum total mining time to 4250h, reduce the total mining time by 1977h (32%), and the production capacity of the first mining stope reaches 5189t, and the comprehensive production capacity exceeds the target value by 20%, which is helpful to solve the problem of insufficient capacity of Daye iron ore in the current state of lagging mining and cutting.
- 1
Simulation Study of a New Bolt Pallet and its Dynamic CharacteristicsAbstract:
Aiming at the problems such as bending, tearing and support failure of most pallets caused by the instantaneous increase of the force between surrounding rock and pallet under the impact loading. First, a new anti-impact large deformation pallet is designed, according to the theory of viscous damping system, the vibration mechanics equation of the new type of pallet under dynamic load is established. Dynamic response characteristics of three different types of pallets, under different impact energy were obtained using Abaqus finite element numerical simulation method. It is found that the new type of anti-impact large deformation pallet has better anti-dynamic load capability, and with the increase of damping ratio, the anti-dynamic load capability gradually increases. The simulation results show that :compared with the flat pallet and adjustable arched pallet, when subjected to the same impact loading, the impact force action time of the new type of pallet reduces by 39.28% and 53.21%, the residual strain of the new pallet reduces by 72.3% and 84.35%, and the energy-absorbing rate increases by 68.9% and 3.45%, the maximum pallet deformation increased by 396.5% and 139.4%, respectively, which illustrated substantial increase in resistance to dynamic loading. The strain of the new type of pallet under different energy is small, indicating that the tray relies mainly on the interaction of internal components to absorb the impact energy, rather than the irreversible deformation of the structure, which can ensure the structural integrity of the tray under dynamic loading.
- 1
Analysis of Surface Collapse Pits and Mining Stability under The Influence of Fault zonesAbstract:
There is a fault zone under a lead-zinc mine, and the mining process leaved a large number of goaf and two collapse pits on the surface, which affects safety production seriously. It is necessary to analyze the stability of the surface collapse pits and the mining area. This article uses the Mathews stability diagram method to calculate the stability index and hydraulic radius, and evaluates the stability of the roof under existing mining parameters. A three-dimensional geomechanical model including underground mining scope and collapse pits has been established, and numerical simulations have been run to calculate the stress and deformation of the collapse pits and mining areas. A microseismic monitoring system has been established to analyze the stability of collapse pits and mining sites through monitoring data at the same time. Analysis shows the stability of collapsed pits and mining areas is good relatively under current conditions. However, the activation of the fault zone has a significant impact, and the energy index of the 3902-3903 mining areas near the fault zone is high relatively. This article can provide certain reference significance for stability analysis of similar mines.
- 1
Analysis and Research on Mining Stability under Wide Filling RoofAbstract:
The popularization and application of the backfill mining method have revolutionized the underground mining mode for metal ore and the recovery method for inter-pillars, thereby enhancing both safety and resource recovery rate. However, in order to ensure the stability of loose backfill and maximize the recovery of roof resources in wide stopes, it is often necessary to leave a certain thickness of roof column, which unfortunately leads to resource wastage. Therefore, the stability of mining under the wide backfill roof was studied. The theoretical calculation of roof stability was conducted to optimize the roof structure and design its strength. Additionally, slurry ratio tests were performed on the mine backfill body to obtain the necessary roof structure and strength requirements for different spans at a height of 20m. Finally, FLAC3d was utilized for simulation verification. The simulation results demonstrate that the designed backfill body exhibits excellent stability and can effectively fulfill the strength criteria as a direct roof for medium and deep hole stopes. The research results can serve as a foundation for the design and implementation of wide stope's filling roof.
- 1
Prediction of Rockburst Grade Based on Multiple Algorithms Based on Data PreprocessingAbstract:
In order to solve the increasingly frequent rockburst hazards and improve the accuracy of rockburst prediction, this paper collects 471 groups of rockburst cases at home and abroad and establishes a rockburst database. The maximum tangential stress (MTS), compressive strength (UCS), tensile strength (UTS) and elastic energy index (EEI) of the surrounding rock were selected as the characteristic indexes, and 10 machine learning algorithms were combined to construct the rockburst prediction model. In order to eliminate the interference of outliers in the samples on the prediction model, this paper proposes to detect outliers according to the grading of rockburst intensity grade, and replace the outliers with 1.5 times the 4th percentile difference. By introducing three oversampling methods, the influence of unbalanced data sets on model accuracy is solved. The genetic algorithm (GA) is used to optimize the parameters of the high-stability model, and the model is deeply evaluated by combining the confusion matrix and multiple evaluation indicators. The results show that ADASYN oversampling improves the comprehensive accuracy by 11.58%, improves the performance of the model the highest, and the weighted average F1 value of the preferred GA-XGBoost model reaches 93%. After applying the proposed model to Jinping II Hydropower Station, Sanshan Island Gold Mine and Maluping Mine for verification, the prediction results are in good agreement with the field conditions, which can provide a new method for future rockburst prediction.
- 1
Influence of water-cement ratio and slag powder ratio on shear strength and damage characteristics of cement-slag powder filled jointsShu Zhilin, 叶义成, 王为琪, 罗斌玉
Abstract:
The shear performance of the joint is the key to control the stability of rock joint. From the perspective of shear strength and economy of filling joint, this study adopts blast furnace slag powder instead of part of cement as filling material, and carries out compressive shear test of cement-slag powder filling joint, combined with acoustic emission (AE) technology. The effects of water-cement ratio (0.7, 0.8, 0.9, 1.0) and slag powder ratio (0, 10%, 20%, 30%, 40%) on the shear strength, AE activity characteristics and economic cost of cement-slag powder filling joints were studied. The results show that the water-cement ratio and slag powder ratio have significant effects on the shear mechanical properties of cement-slag powder filling joints. It is found that there are critical values of 0.8 water-cement ratio and 0.2 slag powder ratio respectively. With the increase of water-cement ratio and slag powder proportion, the AE activity of filling joints tends to increase initially (0.7< water-cement ratio <0.8, 0< slag powder proportion <0.2), and then tends to decrease (0.8< water-cement ratio <1.0, 0.2< slag powder proportion <0.4), which is consistent with the influence of water-cement ratio and slag powder on shear mechanical properties. The cost reduction coefficient corresponding to the increase of peak shear strength was defined. The larger the coefficient, the better the ratio effect. When the water-cement ratio is 0.8 and the slag powder proportion is 0.2, the optimal ratio is obtained. From the economic point of view, the cost of high slag powder ratio and high water-cement ratio is lower, and the cost reduction ratio is greater.
- 1
Macro and Meso Analysis on Suitability of Discrete Element Layered Model Uniaxial Compression TestAbstract:
In the particle distinct element method, the use of modeling method of different particle size inside and outside (layered modeling) can reduce the amount of calculation and effectively improve the accuracy of calculation, and then model and calculate large-scale engineering problems such as tunnels and slopes. Although the layered modeling method is feasible in model generation and contact distribution, it is still unknown whether its mechanical behavior under loading conditions is the same as that of the conventional model and the accuracy of the test results. The effectiveness of the uniaxial compression test of the rock layered model is analyzed from the macro and meso perspective, and the influence of the average particle size ratio of the outer layer to the inner layer and the size of the inner layer model on the compressive strength of the layered model is explored. The research results show that the layered structure of the rock layered model will not have an abnormal effect on its macro mechanical properties under uniaxial compression, and the force and stress can be transferred normally at the interface of the layers. But layered structure will make the model absorb, store and consume more energy. The uniaxial compressive strength of the layered model increases with the increase of the average particle size ratio of the outer layer and the inner layer. As the volume of the inner layer increases, the uniaxial compressive strength of the layered model first increases and then decreases. When the layered model is used to match the uniaxial compressive strength of the rock sample, the average particle size of the inner and outer layers and the size of the inner layer model can be determined first to improve the efficiency of parameter matching. The rock layered model can show the same uniaxial compression mechanical properties and macroscopic fracture characteristics as the laboratory test. The layered structure has no effect on the crack development from meso to macro.
- 1
Study on optimization of mining method and stope structure parametersAbstract:
In Xitieshan lead-zinc mine, the open stoping method was changed to filling method. In order to choose a suitable mining method, the mining method was optimized. Combined with the technical conditions of on-site mining, three technically feasible mining schemes are put forward: sublevel drilling stage open stope filling mining method, small sublevel open stope filling mining method and upward horizontal slicing filling mining method. The technical and economic conditions such as production capacity, dilution loss and mining-cutting ratio of the primary scheme are compared and analyzed, and the mining method scheme suitable for the mining technical conditions of Xitieshan lead-zinc mine is optimized, and the stope structural parameters are optimized by numerical simulation software, which is popularized and applied in mines. The application results show that after the optimization of mining method and stope structure parameters, the stope production capacity is increased by 108.7%, the dilution loss rate is close to the original plan, the mining safety is improved, and better economic and technical indicators are obtained.
- 1
Analysis of Flow Characteristics of Vertical Transportation System for High Well Deep Fuel Oil Pipeline in MinesAbstract:
This article takes the vertical transportation system of fuel pipelines under the Longshou Mine of Jinchuan Group Co., Ltd. as the research object,Based on the actual situation of the mine, a simulation model of the diesel pipeline vertical transportation system was constructed, and the pressure distribution at each node in the oil pipeline was calculated under different flow rates. The pressure characteristics before and after the valve under different masses during valve closure and the pressure distribution before and after the valve under different valve closure times were analyzed, providing theoretical support for the flow characteristics analysis of the fuel pipeline vertical transportation system. Finally, this article proposes a method to suppress the water hammer effect in the vertical transportation system of high well deep fuel pipelines in mines. Simulation shows that installing pressure reducing valves and check valves to reduce valve closing time can effectively reduce or eliminate the water hammer effect generated during the valve closing process.
- 1
Design and Application of Intelligent Cooperative Speed Regulation System for Hydraulic Cone Crushing PlantAbstract:
In order to solve the problems of low automation and high failure rate in the feeding and crushing process of the hydraulic cone crushing plant, the matching relationship between the feeding conveyor belt capacity and belt speed was studied, and the variables related to the crushing host load state were analyzed, and the intelligent cooperative speed control system of the hydraulic cone crushing plant was designed. The fuzzy PID control algorithm was used to design the feed conveyor speed controller through SIMULINK platform, and the simulation comparison was carried out to verify the results, which show that the dynamic performance and anti-interference ability of the fuzzy PID controller is better than that of the traditional Dahlin controller and the PID controller, and it has an excellent control effect. Using the fuzzy theory method, the host current and lubricant oil temperature were taken as input variables to construct the host load state determination rules, and the corresponding cooperative speed regulation strategies were formulated for different load states. The application results show that the intelligent coordinated speed control system can realize the automatic adjustment of the feeding and crushing process of the hydraulic cone crushing plant, and the number of blockage and shutdown failures and energy consumption of the hydraulic cone crushing plant are significantly reduced.
- 1
The Influence of Temperature-Particle Size Coupling on the Dynamic Diffusion Coefficient of Gas into Coal ParticlesAbstract:
To investigate the effects of temperature-particle size coupling on gas desorption and diffusion, the gas desorption experiments at different temperatures and particle sizes were carried out, and a temperature-particle size coupling dynamic diffusion model was constructed to further explore the regularity of the two coupling effects on the gas desorption and diffusion. The results show that: 1 ) The amount of gas desorption increases with the decrease of particle size, and the smaller the coal particle size, the more significant the gas desorption and diffusion in the early stage. 2 ) The higher the temperature, the more gas desorption, and every 10 °C increase in gas desorption has a 10 % ~ 17 % increase, and with the increase of coal particles, the increase is greater. 3 ) The analysis of the dynamic diffusion model analysis reveals that the initial diffusion coefficient D0 and the attenuation coefficient β increase as the temperature rises, while with the increase of particle size, D0 increases by 2.8 times and β decreases by 37 %. 4 ) The process of gas desorption and diffusion is affected by temperature and particle size. In this process, temperature mainly affects molecular activity and pore state, while particle size mainly affects gas content and pore distribution and the changes of particle size show a greater impact during this process. The research results enrich the theory of gas desorption and diffusion, and provide a theoretical reference for the effective prevention and control of gas disasters.
- 1
A Method for Predicting the Fragmentation of Rock Mass Blasting in Mining Areas Based on Measurement While DrillingAbstract:
In mining operations, the distribution of rock blasting fragmentation has a significant impact on loading, transportation, and crushing costs. There are many known methods for predicting the blasting fragmentation of open-pit mines, but none of them are fully applicable to the evaluation of blasting fragmentation in mining areas without bottom pillar segmented collapse. The main reason for this is the variability of the underground environment and the lack of data required to fully characterize the rock mass. With the intelligent development of drilling equipment, Measurement While Drilling (MWD) systems have become an important tool for providing more on-site rock mass information. In a certain mining area, MWD data from 175 boreholes in 17 blasting cycles were collected using the non pillar segmented collapse method, and complete photos of rock fragments for each blasting cycle were recorded. The rock mass morphology before blasting was divided into five types using MWD data, and the rock fragments after blasting were divided into four types using the average fragmentation index X50. The relationship between rock mass types and blasting fragments was studied. The results indicate that intact rock masses tend to produce finer blasting fragments. In intact and slightly fractured rock masses, the challenges and uncertainties faced by charging and blasting processes are relatively small, so the corresponding degree of fragmentation can be better predicted; There is a positive correlation between the discontinuity of rock mass and the size of blasting fragments, thus tending to produce larger blasting fragments. A prediction model for blasting fragments using the bottomless pillar segmented collapse method has been proposed, indicating that using MWD data for blasting fragment prediction is feasible.
- 1
Study on reasonable parameters of roof cutting and pressure relief of narrow coal pillar in gently inclined coal seamAbstract:
In order to solve the problem of large deformation of surrounding rock in gob-side entry driving with gently inclined narrow coal pillar, based on the geological conditions of 020203 working face in Qingyun Coal Mine, the mechanical model of roof cutting and pressure relief narrow coal pillar in inclined coal seam is established. It is calculated that the roof cutting angle should not be less than -1.3°and the roof cutting height should not be less than 9.51 m. FLAC3D numerical simulation is used to simulate the stress and deformation failure law of surrounding rock of roadway under different roof cutting height and different roof cutting angle when 8m narrow coal pillar is left. The results show that when the roof cutting height is 10 m and the roof cutting angle is 0 °, the basic roof can be completely cut off, the stress of narrow coal pillar is small and uniform, and the control effect of surrounding rock is the best. The field test shows that when the blasting borehole spacing is 600 mm, there are many cracks in the borehole, the hole wall is broken to a high degree, and the blasting effect is ideal. After the roof cutting and pressure relief technology is adopted in 020205 track roadway, the deformation of surrounding rock in the area without roof cutting is significantly reduced, which indicates that roof cutting and pressure relief is beneficial to improve the stability of surrounding rock in gob-side entry driving in inclined coal seam.
- 1
Path Planning of Underground Autonomous LHD Machines Based on Improved A* AlgorithmAbstract:
An improved A* algorithm based path planning method for underground automatic driving LHD Machines is proposed. By extracting the roadway skeleton, the node expansion of the A* algorithm is limited to the skeleton area, which ensures that the planned trajectory is located in the central area of the roadway, ensures the driving safety of the automatic driving LHD Machines on the planned path, and greatly accelerates the trajectory planning speed. The validity and superiority of this path planning method are verified by using real mine map data. The influence of different heuristic functions on path planning speed is analyzed, and it is found that Manhattan distance can obtain better path planning speed. The research provides theoretical guidance for the construction and implementation of automatic driving systems of underground LHD Machines, which is of great significance for promoting the development of unmanned and intelligent mines in China.
- 1
Research and Application of Filling Optimization of Jute Fiber Modified Paste PretreatmentAbstract:
In order to solve the technical problems of low quality, high brittleness and poor stability of cement-based cemented backfill in complex deep well environment. Yellow phosphorus slag, electrolytic manganese slag and fly ash industrial solid waste were used to replace cement to prepare new filling cementitious materials. Low-cost jute fiber was used as reinforcement material and jute fiber was pretreated by alkali activation and ultrasonic pretreatment. The fineness of yellow phosphorus slag and electrolytic manganese slag, fiber pretreatment process and fiber content were selected as the research factors, and 36 groups of parallel cross tests were designed to explore the variation of slump, diffusivity, compressive strength and flexural strength of composite filling slurry. The results show that the slump and diffusivity of the filling slurry basically decrease linearly with the fiber content. The large flocs formed by the crosslinking of the fiber and the hydration products increase the collision between the particles and increase the viscosity and yield stress of the slurry. The slump and diffusivity of the electrolytic manganese slag-based paste slurry in the control group and the alkali activation group show a trend of increasing first and then decreasing. With the increase of fiber content, the compressive strength of the filling body in the alkali activation group shows a gradual upward trend, and the fiber content is not the more the better. The appropriate amount of fiber can give full play to the role of anchoring and bonding, significantly enhance the bonding force and mechanical bite force between the filling body matrix, and improve the density of the filling body, thereby improving the crack resistance and deformation resistance. The fiber content of 0.2% is the turning point of the compressive strength change of the control group and the ultrasonic treatment group. Continue to increase the fiber content, the fiber dispersed in the unit volume of the filling body intersects and overlaps to form a structural weak layer, and the pore size structure area increases, resulting in a significant reduction in the compressive strength of the filling body. The filling body prepared by pretreated jute fiber and industrial solid waste has excellent flexural strength. For the control group, the flexural strength reaches the peak when the fiber content is 0.2%. For the alkali-activated group sample, the fiber content of 0.1% is the best content; the flexural strength of the samples in the ultrasonic treatment group was positively correlated with the fiber content. Based on the engineering research background of a gold mine in Henan Province, relevant industrial tests were carried out. By comparing the field test results with the laboratory results, it was found that the error of slump, diffusivity, compressive strength and flexural strength was less than 2%, indicating that the pretreatment of jute fiber modified paste filling material process has important theoretical value and guiding significance.
- 1
Optimization and application of stope structural parameters with room and pillar method for low grade phosphate rockAbstract:
In order to realize the safe and cost-saving mining of a low-grade phosphate mine in Hubei province, the structural parameter optimization of the stope with room-and-pillar method was studied. Firstly, the reasonable range of stope parameters was obtained by simply supported beam theory analysis, and the selection scheme of stope structure parameters was proposed by orthogonal test. Secondly, FLAC3D numerical simulation software was used to analyze the stope stability of each test scheme, and mechanical response indexes such as stress, displacement and plastic zone were obtained. By introducing the information entropy weighting method, considering the cost and benefit indexes, and using the multi-index comprehensive evaluation method based on satisfaction degree, the optimal stope structural parameters were determined as the width of the mine, that is, the dip spacing of the point column is 9 m, the size of the point column is 7 m×7 m, and the strike spacing of the point column is 13 m. The sensitivity is 0.117 room width, 0.074 point column size and 0.011 point column strike distance. The room width has the greatest influence on stope stability. Engineering application examples show that the optimized stope structure parameters can greatly improve the stability of pillar and surrounding rock of stope roof and floor.
- 1
Study on Influencing Factors of Engineering Properties of Fly Ash-based Paste Backfilling MaterialsAbstract:
In order to promote the popularization and application of filling mining, the orthogonal test method was adopted to study the effects of slurry concentration, gangue particle size, gangue binder ratio and fly ash replacement rate on the transportation and mechanical properties of fly ash based paste filling materials through the water loss rate, slump and uniaxial compression tests. The optimum ratio of filling materials in the current test stage is given. The results show that slurry concentration is the main factor of conveying performance, followed by fly ash replacement rate and gangue binder ratio, and the influence of gangue particle size is small. Slurry concentration is also the main factor of mechanical properties, followed by the ratio of gangue and cement, and the effect of fly ash replacement rate and gangue particle size is less. At present, the optimal ratio of paste filling materials based on fly ash is 80% slurry concentration, 0-5mm gangue particle size, 1.0 gangue binder ratio and 30% fly ash replacement rate. The research results are of great significance for reducing the filling cost.
- 1
Mechanism analysis and prevention measures of rock burst in deep phosphate mines based on infrared radiationAbstract:
With the gradual transfer of underground phosphate mining to the deep, rock burst is a common geological disaster in the underground construction process, which causes serious safety risks to underground construction personnel and equipment. Taking the rock burst disaster in Wawu Ⅳ mine section of Yichang as the engineering background, in order to simulate the rock burst site, uniaxial loading test was carried out on the surrounding rock of the phosphorus block in Wawu Ⅳ mine section, and the mechanical mechanism of rock burst under different stress stages was analyzed by using infrared radiation thermal imaging technology, combined with the stress-strain curve and rock failure characteristics under loading. The results showed that the high temperature strip along the shear fracture direction was an important precursor of rock burst and could be used as a sign of rock burst warning. Based on the critical buried depth criterion and the classification method of rock burst based on infrared radiation, the buried depth and intensity of rock burst in Wawu Ⅳ ore section are predicted, and reasonable prevention and control schemes are formulated according to different rock burst grades. Prevention and control measures of rock burst in deep phosphate mine includes improving the physical and mechanical properties of surrounding rock, improving the stress conditions of surrounding rock, optimizing the construction technology and strengthening the surrounding rock.
- 1
Study on the influence of geometric parameters of unequal length fractures on the strength and crack propagation of graniteAbstract:
To explore the influence of fracture geometric size characteristics (fracture angle, length and spacing) on the strength and failure mode of granite, uniaxial compression experiments were carried out on prefabricated double-fractured rocks to analyze the influence of fracture geometry on rock strength characteristics, crack propagation characteristics and failure modes. The results show that the dip angle, length and spacing of primary and secondary fractures will affect the compressive strength of the specimen, and the inclination angle of the secondary fracture will affect the failure mode of the specimen, when the primary and secondary fractures are inclined in the same direction and are not parallel, the compressive strength of the specimen decreases with the increase of angle, and the tensile and shear composite failure of the specimen is the main one, and the compressive strength of the specimen increases with the increase of angle when the primary and secondary fractures are tilted in the opposite direction, and the failure mode of the specimen is tensile failure, and when the primary and secondary fractures are parallel, the tensile failure of the specimen occurs. When the spacing between the primary and secondary fractures is small, the main fracture will have an inhibitory effect on the secondary fractures, and the compressive strength of the specimen is larger, and the inhibition effect gradually changes to mutual influence with the increase of the spacing, so that the compressive strength of the specimen decreases, and the compressive strength of the specimen increases with the continuous increase of the spacing. With the increase of the length of the secondary fracture, the compressive strength of the specimen decreases.
- 1
Numerical Simulation Study on the Influence of Coal Structural Plane Development on the Mechanics and Failure Characteristics of Rock-Coal-Rock CombinationAbstract:
The numerical simulation of a rock-coal-rock combination is created to study the mechanical failure characteristics of the combination under the influence of bedding, coal-rock interface dip angle, and coal-rock height ratio. This is achieved by generating a digital image of coal structural plane development and combining it with the RFPA numerical simulation method. The results show that the compressive strength of the rock-coal-rock combination demonstrates a typical "U"-type anisotropy pattern with varying bedding orientations. The macroscopic shear failure is primarily localized in the coal body, with only a few tensile cracks forming in the green sandstone. The stress of the post-peak part of the composite body exhibits two features: rapid drop and graded decline. These features are caused by the bedding and the dip angle of the coal-rock interface, which significantly impacts the brittleness of the composite body. The combination"s strength and deformation characteristics are mostly determined by the weak coal body. The compressive strength and elastic modulus decrease as the coal height and interface dip angle increase. This study addresses the limitations of prior numerical simulations that assumed coal to be a homogeneous material. The research findings lay the groundwork for exploring how coal structural plane development affects the mechanics and failure characteristics of coal-rock combinations.
- 1
Design of Small Hydraulic Mining Mechanism for Polymetallic Nodules Based on CFD-DEMAbstract:
In order to test and verify the hydraulic mining mechanism through offshore test, due to the power and quality limitations of the equipment carried by the scientific research ship, a small hydraulic mining mechanism for polymetallic nodules was developed. A single water pump was used as the structural design scheme of the three nozzles of the mining mechanism, and the CFD-DEM software was used to simulate the flow field characteristics and collection rate of the mining mechanism. The results of the pool test showed that the acquisition width was 0.3m, and the acquisition efficiency reached 75% when the acquisition power was 4.5kW. A total of 19kg of polymetallic nodules were collected in the offshore test.
- 1
Effects of Different Vegetation Restoration Time on Understory Plant Community and Soil Properties in Open Pit DumpAbstract:
This thesis takes the waste dump of Heidaigou open-pit coal mine as the research area, conducts indoor analysis of relevant data indicators through field survey and sampling, and deeply studies the status of undergrowth vegetation communities and soil properties of the sample plots under different reclamation measures in the waste dump of the mining area. The Kriging spatial interpolation method was used to study the spatial distribution of vegetation characteristics and soil property indicators under forests in reclaimed land. At the same time, the comprehensive index method based on the minimum dataset was used to comprehensively evaluate the ecological quality of each reclaimed sample land in the study area through two scoring models. The remediation effect of AM fungi and plants on the mining waste dump was studied. The main research results are as follows: (1) The dominant species of waste dump are gramineae and compositae plants, and the ecological performance of undergrowth vegetation in the reclaimed sample plots of waste dump is as follows: tree forest>shrub forest>mixed forest with trees and shrubs>grassland. (2) Vegetation reclamation has a significant improvement effect on the soil condition of the waste dump of the Heidaigou open-pit coal mine. Different vegetation types of reclamation methods have a significant impact on the physical and chemical properties and enzyme activities of the soil in the waste dump. (3) The spatial distribution of undergrowth vegetation characteristics and soil properties in waste dump sites is mainly influenced by factors such as vegetation type, reclamation time, topography, interaction of different soil properties, and human activities, showing complex variability. (4) The minimum data set based on non-linear scoring can more accurately replace the total data set to evaluate the ecological quality of the study area. The ecological quality of the sample plots of Pinus tabulaeformis+apricot tree (2004) and Apricot tree (2002) is better. This experiment studied the characteristics of understory plant community and soil physicochemical distribution at different vegetation restoration times, and revealed the driving factors of vegetation and soil variability at spatial scale, which provided a certain basis for the research on the construction of optimal vegetation reconstruction model in mining areas from the perspective of soil improvement.
- 1
Study on the influence of fracture distribution charac[1]teristics on the stability of end face roof under repeated mining of close distance coal seam groupAbstract:
In order to study the influence of fracture distribution characteristics of overlying rock on the stability of end face roof under repeated mining of close distance coal seam group, the fracture distribution characteristics under repeated mining of close distance coal seam group were observed and simulated by using digital image correlation technology ( DIC ), triaxial mechanical characteristic experiment and numerical simulation. The results show that the increase of confining pressure under triaxial stress state will increase the peak strength and elastic modulus of coal samples. With the increase of confining pressure, the failure angle of the sample increases, which easily leads to the spalling of the coal wall, thus inducing the disaster of the end face roof. In the single coal seam mining, the roof breaking is mainly located in the roof position at the coal wall of the working face. Before the mining of the lower coal seam, the rock stratum is affected by the mining of the upper coal seam, the number and density of the cracks are further increased, and the distribution range becomes larger. The crack opening and density of the upper coal seam are significantly higher than those of the lower coal seam. The overburden fissures in the working face undergo a dynamic cyclic change process of generation-development-closure-redevelopment- penetration-reclosure ' in turn. The research content can provide some theoretical support for the stability control of the end face roof of close distance coal seam mining under similar conditions.
- 1
Comparative Experimental Study on Fluidity of Grinded Coal Gangue and Loess Grouting MaterialAbstract:
It is urgent to carry out large-scale comprehensive utilization of coal gangue(CG) according to its physical and chemical properties. Different from the traditional methods of stacking and landfilling, the methods of large-scale harmless consumption of coal gangue goaf are introduced, such as filling in the off-bed area, improving the soil and reclaiming the cultivated land. The methods of coal gangue containing valuable elements such as aluminum, containing minerals such as kaolin, or with high content of beneficial elements such as nitrogen, phosphorus and potassium and low content of harmful heavy metals used in the production of aluminum salt chemicals, kaolin and agricultural fertilizers are briefly described. The problems such as incomplete treatment of coal gangue and hidden danger of secondary pollution in existing technologies are analyzed. It is proposed to establish a high value-added utilization industry chain of "multi-step, stratified and graded", use the residue of agricultural fertilizer for soil improvement and reclamation of cultivated land, and use the solid waste in calcined kaolin for low-standard building materials or roadbed, and use coal gangue at multiple levels to "eat dry and clean", and extend coal gangue from high value-added utilization to mine filling. Large scale consumption of coal gangue with high added value.
- 1
Research and Application of Comprehensive Technology for Ecological Restoration of an Abandoned Mining AreaAbstract:
Abandoned mining areas are the products of large-scale changes in the surface ecological environment system formed after mining, which will seriously restrict the sustainable development of regional ecological economy. Aiming to tackle this issue, an in-depth exploration into an environmentally degraded abandoned mining site was conducted in the present study, thoroughly examining and elaborating on a comprehensive set of restoration techniques. The area under scrutiny has endured years of relentless mining, which has led to catastrophic ecological degradation, evidenced by widespread vegetation destruction, severe land degradation, and intensified soil erosion. An accurate and detailed mapping of the mine site topography was achieved employing the 3D oblique photography techniques. The area was divided into 7 partitions based on the rock and soil type, slope stability and slope angle index. The slope classification research was carried out, and the recommended scheme of ecological greening process suitable for different slope types was formed. A demonstration area of treatment project was selected from the key treatment area of the mining area. According to the geological conditions of the slope in the demonstration area and the comprehensive slope of the slope after leveling, the ecological restoration project was designed and completed according to the actual situation of the demonstration area considering the technical feasibility of the slope protection greening effect. The greening coverage rate reached 100 % of the greening area, and the survival rate of plant seedlings reached 90 %. The research results provide technical support for solving the ecological environment restoration problem of abandoned mining areas and have practical promotion value and reference significance.
- 1
Consistency Identification and Experimental Study of Rock Discontinuities Based on Borehole Optical ImagesAbstract:
The structural plane is a geological interface with a certain scale, and it is important to judge the extension range of structural plane in space in the study of rock mass structure. In this study, the structural plane information of multiple boreholes collected by digital drilling camera is analyzed to judge the structural plane connectivity. Through the mathematical analysis methods such as space geometry and vector, the identification conditions of structural plane connectivity in multiple boreholes were deduced, the possible connected structural planes were quickly screened, and the relevant features were combined to further judge the structural plane connectivity, and a set of structural plane connectivity identification methods based on digital borehole images were formed. Laboratory experiments were carried out to verify the discriminant method. The structural plane of specific parameters was preset in the test block, multiple groups of boreholes were set up and borehole photography tests were carried out to identify and extract the structural plane information in the borehole images, and structural plane connectivity analysis was carried out. The experimental results show that: (1) the identification method of structural plane connectivity can be applied to both the flat and the structural plane with a certain fluctuation angle and roughness; (2) The borehole inclination does not affect the use of borehole photography to determine the structural plane connectivity, and the structural plane connectivity of any two boreholes in the space can be determined by this method; (3) The analytical method proposed in this paper can quickly complete the identification of structural plane connectivity, and is suitable for the identification and screening of massive structural plane connectivity in deep boreholes. The identification method of rock mass structural plane connectivity proposed in this paper has been successfully applied to the slope survey project of Xichang Iron Mine, and the distribution and continuity information of internal structural plane and fracture zone of mine slope have been obtained, which provides a reference for landslide disaster warning and slope reinforcement scheme, and ensures the orderly production of mine.
- 1
Research on the mechanical properties of filler prepared by the synergistic preparation of incineration fly ash slag products cementitious material.Abstract:
Abstract: In order to properly deal with the products of domestic waste incineration (including incineration fly ash and incineration bottom residue), from the perspective of synergistic utilization of solid waste, to explore the feasibility of replacing part of the cement by incineration fly ash and incineration bottom residue, and applying them in the field of mine filling. The incineration fly ash and incineration slag of domestic waste were mixed to prepare the filling body, and the uniaxial compressive strength test was carried out on the filling body with the age of 3d, 7d and 28d respectively, and the compressive strength regression model was established based on the design of the mixing test to analyze the influence of different dosage of incineration fly ash and incineration slag on the mechanical properties of the filling body by combining with the response surface method and the optimization of the mixing ratios. The results show that when the incineration fly ash is 35.3%, incineration bottom slag is 40.4%, cement is 24.3%, and the mass concentration is 70%, the mechanical property index of the filling body reaches the optimum. Incorporating the appropriate amount of domestic waste incineration products can prolong the hydration reaction process and significantly improve the degree of hydration reaction of the cementitious system. According to the analysis of XRD test and SEM test, the main hydration products are hydrated calcium silicate and calcium alumina, which can form a dense mesh structure inside the cement, and thus improve the mechanical properties of the filling body.
- 1
Experimental Study on Heat Transfer Law of Rock under Transient Tigh Temperature Thermal ShockAbstract:
To explore the heat transfer law and thermal stress distribution law of rock under transient high temperature thermal shock, the temperature and temperature gradient distribution in rock at different times were measured by transient high temperature thermal shock test under high temperature oil bath conditions for granite, limestone and sandstone. The following conclusions are obtained: The temperature change process in rock under transient high temperature thermal shock is divided into three stages: rapid temperature rise, slow temperature rise and temperature stability. The temperature gradient change shows a process of rapid increase and then slow decrease to 0. Due to the influence of fluid penetration, the overall thermal conductivity of sandstone with large porosity during thermal shock is more than 26 % higher than that at room temperature in air. The temperature field and temperature gradient field of different kinds of rocks have similar distribution and evolution law. The temperature field is distributed in capsule shape, and the temperature gradient field is distributed in strip shape. The peak value of thermal stress in the rock under transient high temperature thermal shock occurs at about 100 s (in the rapid heating stage). At this time, the rock is more prone to thermal damage, and the damage area is concentrated in the banded range near the sample boundary.
- 1
Research on Structural Damage Rules of Water-saturated Coal Mass Caused by Hot and Cold Cycle ImpactAbstract:
In order to explore the damage pattern of water-saturated coal mass under the impact of cold and heat cycles, a high and low temperature test chamber was used to subject coal samples to multiple hot and cold impacts, observe the changes in cracks on the surface of the coal body, and describe the fractal structure of the coal body cracks. The uniaxial and triaxial compressive strength and permeability of coal samples were tested. The acoustic emission characteristics of coal samples during the compression process were analyzed. The test results show that: with the increase of the number of hot and cold cycle shocks, the fractal dimension increases from 2.17 to 2.50; the uniaxial compressive strength decreases from 5.72MPa to 2.07MPa; the triaxial compressive strength decreases from 27.93 MPa to 20.02 MPa. The initial permeability of the sample increased from 0.26 mD to 1.77 mD. The greater the number of hot and cold cycle impacts, the greater the degree of coal damage and the more significant the cracking effect.
- 1
Analysis of Size Influencing Factors of Stirring Disc of Permanent Magnet Direct Drive IsaMillAbstract:
To explore the effect of the spacing between the mixing pan and the cylinder wall of Permanent magnet direct drive IsaMill on the mineral particles grinding, the Engineering Discrete Element Method (EDEM) is adopted to numerically simulate the movement distribution of grinding media in the mill to analyze the influence of different spacing parameters between the mixing pan and the cylinder wall on the grinding effect in this paper. The Hertz-Mindlin (no slip) contact model is selected to numerically simulate the grinding medium in the mill, and the motion distribution and optimal structural parameters of the grinding medium in the mill are determined by the simulation results. The results show that the grinding effect is best when the grinding medium is near the hole and the edge of the mixing plate, but there is uneven grinding in the mill. With the increasing of the spacing between the mixing pan and the cylinder wall, the average speed and impact energy, and the mill power consumption showed a decreasing trend, while the collision frequency of the grinding medium increased first and then decreased. Considering factors such as the collision frequency of the grinding medium, the power consumption and the energy utilization rate of the mill, the mill shows the best performance when the spacing between the mixing pan and the cylinder wall is 18 mm.
- 1
Study on Mechanical Characteristics and Stability of Discharges in Hexi Dump of Shuichang Iron MineAbstract:
In order to explore the mechanical properties of the discharges with different moisture content and study the stability of the discharges slope in the dump site under loading, rainfall and earthquake conditions, field and laboratory tests were carried out on the Hexi dump of Shuichang Iron Mine, and FLAC3D was used to study the stability of the discharges slope in the dump process and under extreme conditions. The pore water pressure of slope under different rainfall duration and the vertical displacement of slope under seismic conditions are determined. The results show that with the increase of water content, the internal friction Angle and cohesion first increase and then decrease. With the increase of the height of the dump, the safety factor of the dump decreases gradually, and the decreasing range first increases and then decreases. Under the condition of once in 50 years of precipitation, the safety factor of the dump first decreases rapidly with the increase of the rainfall duration, and then turns to a slow decline after 5 days. Under the action of magnitude 7 seismic wave, the slope of the dump is basically stable, but the support such as anchor cable and anchor net should be properly added.
- 1
Crack identification and damage variable analysis based on DIC and acoustic emission technologyAbstract:
In order to study the influence of cross fissures in widely existing rocks on rocks, the rock-like specimens with cross fissures at different angles are tested. The research shows that due to the existence of cracks, the peak stress of specimens with cracks is significantly lower than that of intact specimens. With the gradual increase of secondary crack angle β, the peak stress of specimens presents a "√" type change trend of first increasing, then decreasing and finally increasing. By means of digital image technology (DIC) and acoustic emission technology, the crack types of specimens were identified. It was found that when the secondary crack angle β was small (β≤60°), the cracks were mainly shear cracks. angle increase (β>75°), the cracks are mainly tensile cracks, and both methods can identify the types of cracks well. DIC and acoustic emission technology were used to analyze the damage process of the specimen, and it was found that the damage variables could describe the failure process of the specimen well, and it was also verified that the two methods had good application effects in the analysis of damage variables.
- 1
Study on Macro-meso Damage Mechanism of Fractured Rock Mass under Repeated Freeze-thaw ActionAbstract:
In order to study the microscopic damage law and macroscopic mechanical characteristics of fractured rock mass under repeated freeze-thaw action, the evolution law of rock pores was explored based on nuclear magnetic resonance technology, and the fractured rock model was constructed by particle flow software PFC2D. The improved water particle expansion method was used to simulate the whole process of freeze-thaw cycle of fractured rock, and the strength, energy and failure mode of fractured rock with different freeze-thaw cycles under uniaxial compression were analyzed. Based on this, the influence of fracture parameters on the peak strength and failure mode of rock before and after freeze-thaw was further discussed. The results show that the freeze-thaw cycle aggravates the meso-damage inside the rock, resulting in the increase of pores and pore size inside the rock. Combined with the physical test results, it can be seen that the improved water particle expansion method can better simulate the whole process of freeze-thaw cycle ; the freeze-thaw action reduces the peak strength of the fractured rock by 48.3 %, the energy by 58.09 %, the elastic modulus and the slope of the strength decline section by 33.6 % and 57.9 %, respectively. The plasticity of the fractured rock is enhanced, and the failure mode is changed from simple shear failure to tensile shear failure. The change of fracture dip angle has little effect on rock strength, but it will change the failure mode of rock after freeze-thaw, and the increase of fracture length will reduce the strength of rock.
- 1
Feasibility Study and Application of Rapid Excavation Support Parameter Adjustment in Complex Conditions of Deep Coal RoadwaysAbstract:
The feasibility of adjusting support parameters for rapid coal roadway excavation was investigated, focusing on the transportation roadway of the 1211 working face at Guqiao Mine. A comprehensive analysis was conducted using FLAC 3D numerical simulation software and on-site verification methods to examine the stress and deformation characteristics of surrounding rock under various support density conditions post-excavation.The study indicated that, among the original five support scenarios, the support effectiveness was optimal under condition 5, presenting the most suitable support density for the roadway. Numerical simulations suggested an optimized support scenario 3 with a maximum vertical stress of 4.1 MPa on the roof and floor, an average maximum convergence of 36.25 mm for the roof and floor, an average plastic zone height of 2.2 m. This optimized support exhibited a similar performance to the original support scenario 5, confirming the theoretical feasibility. Field implementation of support scenario 3 resulted in favorable outcomes, showcasing improved roadway stability, minimal deformation, and achieved notable economic benefits.This study accumulated valuable experience in optimizing support parameters for coal roadway support, serving as theoretical reference for similar roadway support endeavors.
- 1
Construction and application of comprehensive evaluation system of stope structural parameters in shallow hole retaining methodAbstract:
The reasonable selection of stope structural parameters is related to the safety and sustainability of mining production, and is particularly important for the shallow hole retaining method with low mechanization and difficult process transformation. Taking a magnetite mine in Bazhong City, Sichuan Province as the engineering background, a comprehensive evaluation system for the stope structural parameters of the shallow hole retaining method is constructed by coupling the rock mass quality classification, the Mathews stability diagram method, the numerical simulation, and the on-site operability evaluation, starting from the internal connections and constraint mechanisms of various methods. The Q system classification method and the modified BQ classification method are selected to provide corresponding parameters support for the Mathews stability diagram method and numerical simulation. Meanwhile, the analysis results of the Mathews stability diagram method and numerical simulation are evaluated by the time on the processes of pry roof, flat field, and ventilation. The results show that the limit size of the mining area based on Mathews stability diagram method and numerical simulation analysis is 15m × 50 m × 50 m (width × length × height) when an ore body with a thickness of 15m is mined. After evaluating the operability of processes such as pry roof, flat field, and ventilation, the maximum size of the stope should be 15m × 40 m × 50 m. Through practical verification, the comprehensive evaluation system in this work has certain feasibility.
- 1
Research on 3D Geological Body Multi information Fusion Modelling and ApplicationAbstract:
In order to provide a precise, composite, and efficient three-dimensional geological body model for the entire mining process of designing, exploration, and excavation, a 3D geological body modeling method integrating multiple information such as UCS, RMR, and RQD was proposed through theoretical analysis, modeling computation, and on-site integration. Results show that the maximum joint spacing of directional drilling rock cores is 13.35 cm, with an average of 0.37 cm, and most of them follow a negative exponential distribution. The joint is the most developed in the northwest direction. Taking exploration line 8 as the boundary, the eastern ore block belongs to the Class III - IV rock masses, while the western ore block belongs to the Class IV rock masses. Analyzing any position profile of the 3D model, at level of 1570 m, the quality of the surrounding rock in the hanging wall is worse than that in the footwall. Within the range of exploration lines 9-11, the surrounding rock in the upper and middle parts is close to Class V rock. Within the range of 1590-1630 m in the hanging wall of exploration line 5, there are Class V fractured surrounding rocks. The new model is significant for safe and efficient production of the entire mining area.
- 1
Anisotropy Analysis of Mesoscopic Damage Evolution of Freeze-thaw SandstonesAbstract:
According to the freeze-thaw cycle, mechanical characteristics and CT scanning test of Shaanxi red sandstone, the pore morphology and anisotropy characteristics of freeze-thaw sandstone are characterized, and the evolution law of sandstone fine view structure is clarified.The results show that the strength of sandstone deteriorates under the freeze-thaw effect, and the compressive strength of sandstone loses 21.99% after 40 freeze-thaw times.With the transformation of spherical, columnar and branch-like pores into complex reticular pores with the progression of freeze-thaw cycles, the contribution ratio of reticulated pores increased from 13.4% to 97.6% after 40 freeze-thaw cycles. The anisotropy value of sandstone is 1.06 before freezing and thawing, which can be regarded as an isotropic body, and the pores are preferentially developed laterally under the influence of pore connectivity and gravity, and the anisotropy characteristics of sandstone increase first and then decrease. The pore evolution of freeze-melted sandstone can be divided into three stages: "lateral slow growth-lateral rapid growth-stable development". The research results can provide a reference for accurately understanding the rock destruction mechanism in the cold area.
- 1
A Study on the Fracture Characteristics and Instability Mechanisms of Sandstone with Parallel Double Fractures Based on Discrete Element Method.Abstract:
The study on the influence of fractures on the stability and deformation characteristics of rock masses aids in understanding the mechanisms of interaction among fractures. Utilizing the Particle Flow Code in 2 Dimensions (PFC2D), numerical models of rock masses containing parallel double fractures with different spatial distributions were established. Uniaxial compression tests were conducted to analyze their load-induced damage characteristics, micro-crack evolution, and stress fields. Combining macroscopic failure characteristics to investigate the instability mechanisms of the specimens. Results indicate that the diverse spatial distributions of the three types of double fractures induce variations in the progressive damage process and mechanical properties of sandstone. These distributions influence micro-crack distribution, quantity, and inclination, resulting in significantly different degrees of rock bridge failure and subsequent formation of distinct fracture regions. Comparative evaluation of peak stress distributions among different models using equivalent stress contour maps, in conjunction with macroscopic fracture characteristics, suggests that the spatial distribution structure of fractures affects stress-bearing surfaces and stress transmission pathways in the specimens from the perspective of external forces. The research findings offer valuable references for engineering practice and rock mechanics studies.
- 1
Study on the Difference of Failure Characteristics of Frozen Soil after Freeze-thaw Cycle on Thick Coal Seam in High Cold AreaAbstract:
In order to reveal the freeze-thaw cycle damage characteristics of the permafrost body on the thick coal seam in alpine region, taking the permafrost body on the thick coal seam in alpine region as the research object, using WAW-600B type electro-hydraulic servo rock uniaxial experimental machine to carry out the rock mechanics experiments, and it is concluded that the structure of the permafrost soil body will be changed by different numbers of freeze-thaw cycles under the same water content, and the peak strength as well as the elasticity modulus of the artificially permafrost specimen will be significantly decreasing. It was found that (1) under a certain water content condition, the cohesive force and the angle of internal friction showed a negative exponential function with the number of freezing and thawing cycles, and both of them reached the peak value at the time of 0 freezing and thawing cycles. (2) With the increase of the number of freeze-thaw cycles, the peak strength of artificially frozen soil specimens under different water content conditions is a quadratic parabola with "opening downward"; similarly, the modulus of elasticity is a quadratic parabola with "opening downward"; the modulus of elasticity is a quadratic parabola with "opening downward". Similarly, the elastic modulus - number of freeze-thaw cycles fitted function curve is a quadratic parabola with "opening downward". The decrease in modulus of elasticity and peak strength depends on the rate of strain accumulation and the rate of damage development. (3) From the viewpoint of micromechanics, freeze-thaw cycle is a complex process in which the soil body constantly generates microdamage and repairs itself, thus causing structural changes in the soil body. After several freeze-thaw cycles, the permeability coefficient of permafrost gradually increases, the water migration speed is accelerated, the effect of freezing and expansion force is obvious, the fine-grained soil is gradually compacted, and at the same time, a large number of new-born microfractures are generated, and the porosity gradually increases. The effect of the number of cycles on the permafrost body was verified, providing reference for the mines in Jiangcang mining area and other mines with similar conditions.
- 1
Study on Deformation Control Mode and Support Optimization of Broken Surrounding Rock Roadway in Jinchuan No. 3 Mining AreaAbstract:
Aiming at the high cost of double-layer spray anchor net support for the more developed roadway with joint in Jinchuan No. 3 mining area, a new single-layer spray anchor net support method with higher economic benefit is proposed. FLAC3D software and Tecplot software are used to carry out numerical simulation calculation of three different reinforcement bar layout modes combined with single-layer spray anchor net support schemes, analyze the distribution of plastic zone of roadway surrounding rock, the change law of roadway displacement, the safety distance of section and the overall safety factor of surrounding rock, and make comparison and optimization based on labor cost, material consumption and construction technology. The results show that the combination of single-layer spray anchor net and reinforcement bar arrangement is the best support scheme. The field test shows that the control effect of the support scheme on the roof and the deformation of the two sides of the roadway is basically the same as that of the original double-layer spray anchor net support, and the supporting body meets the requirements of the roadway support strength and stability. The research results show that reasonable bar layout has a good effect on deformation control of roadway with more developed joints, and can provide a reference for the selection of roadway support methods for roadway with similar joints.
- 1
Study on the Influence of Bolting and Shotcrete Support Parameters on Plastic Zone Volume Based on Index Evaluation FunctionAbstract:
In order to further study the influence of different supporting methods and supporting parameters on the volume of plastic zone, an orthogonal experimental scheme was designed with four factors including the thickness of shotcrete, the length of bolt, the row distance of bolt and the distance between bolt and each factor contains three levels, taking an approach roadway of a horizontal section of a metal mine -410m as the research object. Using FLAC3D to simulate 9 schemes, systematically study the changes of plastic zone volume of surrounding rock under different schemes, and then construct index evaluation function through range analysis to study the comprehensive influence of 4 index factors on plastic zone volume. The results show that the influence on the volume of plastic zone is the thickness of shotcrete, the length of bolt, the spacing of bolt and the spacing of bolt row, and the optimal supporting combination parameters are the thickness of shotcrete 150mm, the length of bolt 2.2m, the spacing of bolt row 0.9m and the spacing of bolt 780mm. The looseness ring monitoring points are arranged in the corresponding position to carry out engineering monitoring, and the looseness ring test results are compared with the simulation results, which are consistent with the simulation results and meet the engineering requirements. The research results provide a reference for the selection of roadway supporting parameters to a certain extent.
- 1
Study on the Effect of Air Curtain on Air Leakage in Goaf and Gas Accumulation in Upper CornerAbstract:
In order to effectively prevent air leakage in goaf and gas accumulation in upper corner, it is proposed to arrange air curtain system in upper corner. By forming an air curtain wall to block the air leakage on the return air side of the goaf, and at the same time, the upper corner is pressurized to achieve the effect of uniform pressure plugging. The effects of air curtain on air leakage, oxidation zone area, upper corner gas and stope energy distribution under different jet width, velocity and angle parameters were studied by comsol numerical simulation software. The results show that with the increase of air curtain jet velocity and width, the air leakage in goaf and the gas in upper corner decrease gradually, and the area of oxidation zone decreases first and then increases. Under the same air leakage reduction, the large width and low velocity are better than the small width and high velocity;increasing the jet angle can effectively reduce the area of air leakage and oxidation zone in goaf, but there is an optimal angle. Considering comprehensively, the air curtain has the best effect when the jet width is 25 cm, the angle is 20 ° ~ 30 °, and the velocity is 7 ~ 8m / s; the air curtain can disperse the gas in the upper corner, and because the air curtain is too cut off the eddy current generated on both sides, the gas can be sealed inside the goaf, which can effectively prevent the gas accumulation in the upper corner; the air curtain blocks the air flow out of the return air side, so that the internal pressure distribution in the goaf tends to be average, forming a pressure equalization effect, reducing the air flow into the goaf, thus effectively reducing the air leakage in the goaf.
- 1
Mechanistic Studies on the Flotation of Coal Quartz by Hydroxamic Acid-based Trapping AgentsAbstract:
The rock minerals of Malan coal mine were taken as the research object to investigate the flotation effect and mechanism of hydroxamic acid-based collectors on the minerals. The results of flotation test and quantitative analysis of XRD showed that among the three kinds of collectors, sodium octyl isohydroxamic acid has the best flotation effect, and the dosage of 450 g/t of the agent and 750 g/t of sodium hexametaphosphate can reach 78.54% of the concentrate yield, and the quartz content in the tailings can be increased from 85.16% to 91.70%. The mechanism of the interaction between the agent and the mineral was analyzed by density flooding, contact angle test, infrared spectroscopy and molecular dynamics simulation. Characterization of the electronic structure properties of quartz crystals and the electrostatic potential distribution energies of the agent molecules yielded that the adsorption sites of sodium salicylhydroxamic acid, sodium benzylhydroxamic acid and sodium octylisohydroxamic acid on the quartz surface are the head group part which can ionize the cationic Na+ in the solution. The molecular simulation results show that the absolute value of adsorption between sodium octyl isohydroxamic acid and quartz is larger than that between sodium salicylhydroxamic acid and sodium benzohydroxamic acid and quartz, indicating that sodium octyl[ ] isohydroxamic acid is more likely to be adsorbed on the quartz surface.
- 1
Emulsification of Diesel Oil and Its Application in Coal Gasification Slag FlotationAbstract:
Coal gasification slag is a carbon-containing waste residue produced during high temperature gasification of coal. At present, the residual carbon is mainly recovered by flotation. Aiming at the problem of large consumption of flotation reagents due to the large specific surface area of residual carbon, the traditional collector diesel is compounded with additives such as engine oil and stirred emulsification to improve the collection performance of the reagents. In this paper, the effects of different emulsification conditions on the stability and particle size of emulsified diesel were studied. The results show that the particle size of emulsified diesel is closely related to the emulsification conditions. The smaller the HLB value, the larger the amount of additive, the larger the water-oil ratio, the longer the stirring time, and the higher the stirring speed, the smaller the particle size of the emulsified diesel. The compound engine oil is beneficial to reduce the particle size of the emulsion, and the smaller the particle size of the emulsified diesel oil, the higher the stability of the agent. When emulsifier HLB value is 6, m(diesel oil) : m(emulsifier) : m(engine oil) : m(water) = 10 : 0.75 : 0.6 : 20, stirring speed 1800rpm, stirring time 40min, the obtained emulsified diesel oil was oil-in-water emulsion, and the particle size of the emulsion was small, where D50 was 3.19μm and D90 was 61.50μm. The flotation test shows that the emulsified diesel oil has stronger collecting ability and higher flotation speed than diesel oil. Under the same combustible recovery, diesel oil can be saved by more than 40 % through diesel emulsification, which is of great significance for strengthening the saving of energy resources and reducing carbon emissions.
- 1
Risk situation analysis of ventilation system based on five element connection numberSHI Shuai1, MA Zhishun1, ZHANG Haiyun2,3Abstract:
In order to determine the risk situation of underground metal mine ventilation system more scientifically and reasonably, based on the construction of the reliability evaluation index system of the ventilation system, the IAHP weighting method was used to determine the weight of the index, and a mine ventilation system risk evaluation model based on the five element connection number set analysis method was established. A case study was conducted on a gold mine in Shandong Province. The results show that the reliability of the mine ventilation system is of a good level, and the evaluation results are consistent with the actual situation, verifying the adaptability of the five element contact number set pair analysis method in the reliability evaluation of the mine ventilation system. This model can objectively and comprehensively reflect the determinacy and uncertainty in the reliability evaluation process of ventilation systems, achieving a combination of static and dynamic evaluation of ventilation systems, and providing new ideas for evaluation work.
- 1
Calculation and Analysis of Transient Negative Sequence Capability of Wind Turbines Used in Large Mining AreasAbstract:
The harm of negative sequence current to the temperature rise of wind turbines has been repeatedly confirmed in the operation practice of power systems in large mining areas. For high-power generators in large mining areas, it is crucial to accurately calculate the impact of negative sequence current on the temperature rise generated by the generator. By analyzing the transient negative sequence capability of large-scale wind turbines in mining areas, and taking a 5.5MW high-power wind turbine as an example, the finite element method is used to calculate the negative sequence loss and corresponding temperature rise generated by transient negative sequence current. The research results of large-scale wind turbines in mining areas show that the larger the transient negative sequence current, the greater the negative sequence loss and temperature rise harm generated by the generator, The calculation process and results will lay the foundation and provide research methods for the transient negative sequence capability of installing larger capacity wind turbines in large mining areas.
- 1
Research on the selection of water reducing agent for full tailings paste filling in a certain mineAbstract:
In order to ensure the safe and efficient transportation of high concentration tailings filling slurry, the effects of different water reducing agents on the rheological properties (yield stress) of the slurry and the strength of the filling body were analyzed qualitatively and quantitatively. The results show that after adding three types of rheological agents, the flowability of the high concentration slurry is significantly improved, and the higher the dosage, the greater the decrease, and the better the rheological improvement effect of the slurry. After adding rheological agents, it has a significant impact on the strength of the filling body at 1 day, but has almost no effect on the strength at 3 days, 7 days, and 14 days. Among them, YSKJ01 has the best effect, and when the dosage is 0.4%, the various properties of the full tailings filling material reach the optimal value. And from a microscopic perspective, the mechanism of the effect of water reducing agents on improving the flowability of high concentration filling slurry was elaborated.
- 1
Research and Development of a Multi-Parameter Fusion Digital Rock Model and Information SystemAbstract:
Rocks are heterogeneous, multi-porous, mineral composites with complex, nontransparent internal structures. This severely limits research on rockfracture and rockmechanics. Digital Rock Technology helps to demystify rock and provide transparent and refined structural characterization. To address the difficulty of synchronous integration of multiple information such as pores and mineral properties in digital rock models, this study used CT scanning and high-resolution electron microscopy to obtain information on rock pores and mineral composition. Based on the differential idea and the matter-element theory, a multi-parameter fusion digital rock model was constructed, and a corresponding information management system was designed and developed. The results show that the model and information system can directly observe primary and secondary pores in rocks, effectively process meso-structure data, and achieve big data retrieval and dynamic, coherent, and hierarchical data management of different stages of rock fracture development across multiple objects and scenarios. This research will provide significant support for big data analysis and processing in rock mechanics, laying an important foundation for the integration of digital rock data.
- 1
Study on the optimal azimuth angle of the mine approach in deep metal minesAbstract:
Appropriate azimuth angle of the mine approach can effectively control the effect of ground pressure to reduce the deformation and damage of the approach, ensure the safe production of the mine, and improve the economic benefits of the mine. Based on the detailed investigation of the damage of the approach road in the -400m stage of Zhang Fushan mine of Jinshandian Iron Mine, two representative sections of the -500m stage to be mined were selected, and numerical simulation was used to study the destruction pattern of the approach road in case of changes in the azimuth angle by taking into account the influence of tectonic stress and steeply inclined dominant structural surfaces. The results show that: the smaller the angle between the approach azimuth and the maximum principal stress, the smaller the volume of rock shear damage area, and the rock shear damage mainly occurs at the top of the approach; the smaller the angle between the approach azimuth and the steeply inclined dominant structural surface, the larger the volume of nodal shear damage, and the nodal shear damage mainly occurs in the diagonal upper or lateral side of the approach, and the damage area is generally perpendicular to the nodal surface; the steeply inclined dominant structural surface exacerbates approach deformation, causing a larger arch in the approach. The steeply inclined dominant structural surface aggravates the deformation of the approach, which causes larger displacement of the arch and sidebonds, and the displacement of the sidebonds is larger than that of the arch, thus causing large deflection deformation of the approach section. The results of the study can provide optimization ideas for the layout of approach roads in the same type of mines.
- 1
Research on License Plate Localization Algorithm in Underground Complex Environment Based on YOLOv7-CA-Fasteryeyongjing, 韩斌, 胡亚飞
Abstract:
In underground environments, traditional license plate positioning algorithms are susceptible to unfavorable conditions such as glare, reflections, and dust, which leads to problems of reduced contrast between the license plate and the body and weakened edges of the license plate. To address the above problems, a high-precision localization detection algorithm for license plate based on improved YOLOv7 was proposed. Firstly, Coordinate attention mechanism was incorporated into the YOLOv7 neck network to enhance the network's ability to learn and extract license plate features, weaken the background information of the body, and improve the accuracy of license plate detection in low-quality images. Then, the FasterNet lightweight convolution module was combined with the efficient layer aggregation networks of YOLOv7 backbone, which simplifies the arithmetic complexity of the algorithmic model and improves the speed of target detection while guaranteeing the accuracy and stability of the model detection. The experimental results show that the mean average precision of the YOLOv7-CA-Faster model reaches 97.8%, which is an improvement of 2.5 percentage points compared to the pre-improvement YOLOv7 model. The detection accuracy and recall increased by 1.7 and 1.9 percentage points respectively. The model params, floating-point operations, and the memory occupancy are reduced by 11.7%, 19.1%, and 12.0% respectively, which indicates that the model has become more lightweight. Compared with mainstream target detection models such as Faster-RCNN, SSD, YOLOX-m, and YOLOv5-m, the YOLOv7-CA-Faster model has a large advantage, with the mean average precision improved by 8.1, 6.4, 3.3, and 2.9 percentage points respectively. In the underground environment, the improved YOLOv7-CA-Faster algorithm has good detection performance, which provides technical support for accurately recognizing vehicle numbers, as well as promoting the development of intelligent control of vehicles in underground mines.
- 1
Research Progress on Preparation of Mineral Materials from Iron TailingsAbstract:
With the increasing demand for iron ore, the amount of treatment is gradually increasing, resulting in an increasing number of tailings after treatment. The storage of iron tailings occupies a large amount of land resources and affects the ecological environment. Therefore, the comprehensive utilization of iron tailings has become a research hotspot. The chemical composition of iron tailings is similar to that of natural sand. Iron tailings can be used as raw materials for the preparation of concrete, ceramics, glass ceramics and other objects. The preparation of mineral materials from iron tailings realizes the comprehensive utilization of iron tailings materials, which meets the requirements of effective utilization of solid waste resources under the goal of ‘ double carbon’ . Based on the research results of the above different types of composite mineral materials prepared by iron tailings, the advantages and prospects of the research and application of mineral materials prepared by iron tailings are analyzed and expounded, and reasonable suggestions for further research in the future are put forward.
- 1
Semi-supervised Intelligent Proportioning Prediction Method of Mixed Coal Based on Weighted Similarity of Probability Density Normal DistributionZhang Qian, 王然风, 付翔, 王珺, 韩杰, 魏凯
Abstract:
Some raw coal selected from coal preparation plant comes from multiple mines or different working faces of the same mine. When there is no capacity for separate mining and transportation underground and it is difficult to determine the proportion of mixed coal, direct selection will cause large fluctuations in coal quality, affect the separation process effect and other problems. Moreover, the existing prediction methods for the proportion of single coal in mixed coal mostly use supervised learning algorithms that require a large number of label data for training. In view of the above problems, a semi-supervised intelligent proportion prediction method of blended coal based on weighted similarity of probability density normal distribution is proposed. Stepwise discriminant analysis and K-means++algorithm are used to optimize the multi-cluster feature selection (MCFS), obtain clustering data labels, and interpret them to achieve coal quality information discrimination. Fit the normal distribution probability density curve of each single coal characteristic variable, and combine it with the ReliefF algorithm to calculate the feature weight to analyze the similarity of probability density distribution, achieving the prediction of mixed coal ratio.The experimental results show that, compared with the mixed coal prediction model that uses no weighting, weighting based on the coefficient of variation method, and weighting based on the model that combines the ReliefF algorithm and Kullback Leibler (KL) divergence calculation probability density normal distribution weighted similarity to achieve mixed coal ratio prediction has a high degree of consistency with the actual situation, and the prediction accuracy has significantly improved to 95.66%, It meets the requirements of accurate and rapid prediction of mixed coal ratio in the production site.
- 1
Research on material level control and optimization of steady state discharging parameters of filling mixing and discharging systemAbstract:
The material level control of filling mixing equipment is the key point to realize the homogenization of slurry. The frequent fluctuation of material level and flow rate has a great influence on the preparation quality and transmission pipeline network, which leads to the decrease of filling quality and the increase of cost. In order to explore the problem that the filling level and discharge flow of a mine are difficult to control, the calculation formula of the indenter loss of the mixing and discharging system is proposed by constructing the model and combining with the theoretical calculation. The analysis shows that the diameter D of the discharge pipe is inversely proportional to the flow velocity v of the discharge port, and the ratio of yield shear stress to bulk density τ0/γ, the ratio of viscosity coefficient to bulk density η/γ is proportional to the mixing barrel level HJ. The test results of the filling material show that with the increase of the concentration Cw, τ0/γ and η/γ also increase, which is beneficial to the improvement of the material level in the mixing barrel. Taking Cw=74%, 72%, 70%, 68% and D=140 mm, 125mm as variables, the calculation and analysis show that under the two working conditions of Cw = 74 %, D = 140mm and Cw = 72 %, D = 125 mm, the HJ is 1.59 m and 1.65 m respectively, which is in the best operating material level range of the mixing bucket. In order to further verify the rationality of the formula, the Space Claim software is used to construct the model of the mixing and discharging system, and the numerical simulation is carried out based on Fluent. The relative error between the simulation results of the pressure head loss per unit length of the discharge pipe and the outlet velocity of the slurry and the theoretical calculation value is controlled within 10 %, respectively, indicating that the proposed calculation formula of the pressure head loss of the mixing and discharging system has good guiding significance in optimizing the material level control and steady-state discharging.
- 1
Optimization Study on Separation Process for Magnetizing Roasting Products of Fine-grained SpeculariteAbstract:
Magnetic roasting – magnetic separation was an effective way to treat fine-grained specularite, which has poor performance in conventional high intensity magnetic separation. The separation process for magnetic roasting products of fine-grained specularite was optimized, and the effects of dry discarding, two-stage grinding-magnetic separation process, one-stage grinding-magnetic separation process and one-stage grinding-coarse and fine classification-magnetic separation process of roasted ore on concentrate indexes were investigated. The results showed that the concentrate with Fe grade of 53.82% and Fe recovery of 87.09% was obtained under the magnetic separation process of one grinding process, one roughing and one scavenging. In the concentrate product, the iron grade of +0.038 mm fraction was more than 55 %, and the iron grade of -0.038 mm fraction was only 51.98 %. Therefore, it was necessary to increase the fine screen classification and carry out weak magnetic separation on the undersize products. The final recommended flowsheet was one grinding, one roughing, one scavenging, coarse and fine classification, one cleaning, with the conditions of grinding fineness of -0.074 mm accounting for 85.00%, the roughing magnetic field of 0. 09 T, the scavenging magnetic field of 0. 11 T, the fine screen with an aperture of 0. 038 mm, and the cleaning magnetic field of 0.06 T for undersize products, the concentrate with Fe grade of 56.16% and Fe recovery of 85.84% was obtained, which provided a technical reference for the efficient recovery of fine-grained specularite by magnetic roasting-magnetic separation.
- 1
Practice of Directional Hydraulic Fracturing in Soft and Low Permeability Coal Seam for Permeability Improvement and Gas DrainageAbstract:
Aiming at the problem that the soft and low permeability outburst coal seam has large gas content and is difficult to pump, and the stone door is prone to protrude in the process of coal uncovering, this paper proposes a directional hydraulic fracturing anti-reflection technology. Firstly, the mechanism of directional hydraulic fracturing and anti-reflection was clarified, and the cracking pressure, flow rate and water injection amount of the test site were 22.8~30.5MPa, 130~200L/min and 216m3, respectively. According to this, four hydraulic fracturing drill holes and two crack guiding holes were constructed in the unextracted roadway. During the fracturing process, the pump pressure, average water injection flow rate and single-hole water injection amount reached 28~31MPa, 140~177L/min and 260~330m3, respectively, which were basically consistent with the theoretical calculation data. The test results show that after directional hydraulic fracturing, the influence radius is greater than 30m, the permeability coefficient of coal seam is 0.83986m2/MPa2?d, which is increased by 60 times; the concentration of single-hole gas is increased by 50~80%, and the purity of single-hole extraction is 1.9 m3/min, gas extraction capacity increased by 90%. After the directional fracturing, the amount of coal mining drilling was reduced by 64%, and the mining time was 36 days earlier than the expected construction period. The successful test of this technology in Panyi Mine can provide a good reference for similar gas control projects in adjacent mining areas.
- 1
Study on Mine Earthquake Response Rule and Propagation Mechanism of Deep Longwall Panel with Large Face LengthZHANG Yiyun, 李成海, 唐磊, 杨海涛, 熊洪恩, 周强
Abstract:
Deep longwall panel with large face length stress environment is complicated, mining disturbance induces strong mine earthquake, threatening the safety of mine mining. In order to explore the temporal and spatial response characteristics of mine earthquake and the vibration wave propagation law of different energy levels and different regions during the mining of longwall panel with large face length, the 130608 longwall panel with large face length of Meidoushan Coal Mine was taken as an example, based on the arrangement of underground microseismic monitoring network, theoretical calculation and data analysis were adopted for in-depth analysis. The results show that the microseismic events of the longwall panel with large face length are mainly distributed in the production shift and the working face 100-300 m ahead. Under the same vibration wave propagation speed, the larger the microseismic energy level is, the larger the propagation distance is; while under the same vibration wave propagation distance, the larger the microseismic energy level is, the larger the propagation speed is. In comparison, the vibration velocity and attenuation coefficient of the vibration wave located at the source of the gob are the largest, and the vibration wave propagates the fastest in the area of the top and bottom strata of the advanced working face. The main control factors and attenuation formulas of vibration wave propagation under different energy levels are determined, and the risk identification method of vibration wave propagation is proposed, which has important guiding significance for the prevention and control of dangerous mine earthquakes.
- 1
A Study on the Efficient Recovery of Molybdenum from Iron Tailings Using a Novel Collector MOF-100Abstract:
The main metal minerals in an iron tailing in northern China were molybdenite, magnetite and pyrite or pyrrhotite. Molybdenum minerals and iron minerals were closely symbiotic, and they were finely embedded. The content of molybdenum metal was only 0.08%, and the content of sulfur was 1.75%. Due to the serious alteration and oxidation of the mineral surface in the tailings, the flotation activity of molybdenum was very low, and it’s difficult for traditional collectors to achieve effective recovery. In this paper, a new collector MOF-100 with both collecting ability and selectivity was introduced to efficiently recover the molybdenite and achieve good beneficiation results. The suitable reagent system for flotation was determined by the test of mineral processing conditions. The results showed that under the condition of grinding fineness of -0.075 mm accounting for 85%, the molybdenum concentrates with Mo grade of 40.67% and Mo recovery of 63.89% could be obtained by using the new high-efficiency collector MOF-100 through the closed-circuit process of one roughing, two scavenging and eight cleaning, which realized the comprehensive recovery of molybdenum resources in tailings.
- 1
Full-cycle overburden migration law of high-stage fully-mechanized caving face in steeply inclined extra-thick coal seamAbstract:
With the increase of mining depth, the situation of rock burst disaster is becoming more and more serious in the high-stage fully mechanized caving face of steeply inclined thick coal seam. It is very important to explore the law of overburden movement under the condition of multi-working face of steeply inclined thick coal seam group for safe and efficient mining. Taking Wudong Coal Mine as the engineering background, a three-dimensional physical model test was established. The three-dimensional photogrammetry system was used to collect the surface displacement data of the model, and the Matlab was used to draw the overburden displacement cloud map. The law of full-cycle overburden movement in the high-stage fully-mechanized caving face of steeply inclined and extremely thick coal seam was revealed, and the relationship between mine pressure and overburden movement in the working face was analyzed. The results show that : ( 1 ) With the increase of mining depth, the vertical displacement of overlying strata changes from ' N ' type distribution to ' V ' type distribution from top to bottom. Working face mining is accompanied by overburden fracture and slump, forming a ' fracture-slump-self-filling ' effect. ( 2 ) The movement law of overlying strata in 43 # coal face : coal seam roof caving-direct roof caving-main roof breaking and showing hinged structure ; the migration law of overlying strata in 45 # coal face : mild collapse of overlying strata-severe destruction of upper strata-overall collapse of rock pillars between coal seams. ( 3 ) Before the mining of + 550 level, the support pressure in 43 # coal seam is generally greater than that in 45 # coal seam. After the mining of + 525 level and + 500 level, the support pressure in 45 # coal seam increases sharply.
- 1
Mechanisms of influence of the benzene ring structure of surfactants on the wettability of coal dustsAbstract:
Surfactants can effectively assist in the suppression of coal dust. In order to reveal the microstructure of surfactants on the wettability of coal dust, two slightly different surfactants were selected in this study, and the influence of the benzene ring structure on the wettability of coal dust was analyzed from various angles and by various means. The surface tension experiment was used to predict that OP9 containing benzene ring structure had lower surface tension and faster reduction rate; the contact angle and settling time indicated that OP9 containing benzene ring structure could adsorb more on the surface of lignite through hydrophobic interaction and π-π stacking, and had a stronger ability to enhance the wettability; the HOMO and LUMO distributions of the two surfactants were calculated by using DFT, and it was obtained that OP9 The HOMO and LUMO distributions of the two surfactants were calculated by DFT, and it was found that OP9 had more adsorption sites with lignite; finally, the adsorption energies of different adsorption systems, the relative concentration distributions, the rms displacements of the water molecules, and the number of hydrogen bonds of the systems were calculated, and it was obtained that the OP9-modified coal was able to produce more hydrogen bonds to restrict the movement of water molecules in the Z-axis, and the hydrophilicity of the lignite was strengthened. This study can provide a strong theoretical basis for the inhibition of coal dust.
- 1
Research on Directional Water Jet Pressure Relief and Permeability Enhancement Technology for Loose and Soft Coal Seam in Wuyang Coal MineAbstract:
In order to solve the problem of many gas endowment in loose coal seams and poor permeability of coal seams. A combination of numerical simulations and field tests in Wuyang coal mine was used to study the directional water jet pressure relief and permeability enhancement technology for penetration boreholes. Combining the actual conditions of Wuyang coal mine and the analysis of numerical simulation results, the better directional water jet cavitation process parameters were derived as follows: cavitation in the top plate, cavitation thickness 0.4m, cavitation radius 0.8m and drilling spacing 5m. Through the layer directional water jet equipment field test results show that: the improved equipment can achieve parallel to the coal seam soft layered cavity making, the top plate directional water jet drilling daily gas extraction concentration increased by about 30% on average. Directional water jets at the top of the coal seam form a high rate of flat pressure relief space, which can effectively improve the overall pressure relief effect of the coal seam and increase the efficiency of gas extraction from the borehole.
- 1
Study on the Influence of Bedding Angle on the Mechanical Properties and Fracture Failure Behavior of SandstoneAbstract:
This paper aims to investigate the mechanical properties and crack propagation behavior of sandstone under varying bedding angles. The study involves conducting tests on the compressive strength and tensile strength of sandstone samples with five different bedding angles.The failure load was obtained by using the semi-circular disk specimen to test the mode I fracture toughness, and the fracture toughness was calculated by using the finite element analysis software to study the influence of bedding angle on the mechanical properties of sandstone. The results show that the bedding angle has a significant effect on the compressive strength, elastic modulus and tensile strength of sandstone, and the fracture toughness decreases with the increase of bedding angle. This paper also includes an analysis of crack propagation paths. It was observed that the failure of specimens with 0° and 30° bedding angles is less influenced by the bedding plane. However, when the bedding plane's dip angle exceeds 45°, the sample's failure is primarily affected by the dip angle of the bedding plane, leading to an expansion of the failure path along the bedding plane's dip angle. The experimental findings provide valuable insights into how the bedding angle affects the fracture failure of sandstone and offer a fresh perspective on the analysis of bedding angle's influence on crack propagation paths.
- 1
Extension Cloud Model for Wear Risk Assessment of Filling Pipeline Based on DEMATEL MethodAbstract:
In order to scientifically and reasonably determine the risk level of filling pipeline wear, the DEMATEL method and extension cloud theory were introduced, and a DEMATEL improved CRITIC extension cloud model for filling pipeline wear risk assessment was established. On the basis of constructing an evaluation index system, the DEMATEL method is applied to study the influence relationship between indicator factors. The DEMATEL centrality improved CRITIC method is used to obtain the comprehensive weight of indicators. Based on the principle of extension cloud theory, four mines are taken as examples to calculate the cloud comprehensive correlation degree to evaluate the wear and tear risk status. The results show that pipe diameter and slurry concentration are key factors for the wear of deep well filling pipelines. The wear risk of pipelines in all four mines is at a high risk level, which is completely consistent with the evaluation results of uncertain measures and variable fuzzy set theory. This indicates that the DEMATEL improved CRITIC extension cloud model has applicability and effectiveness in the risk assessment of pipeline wear.
- 1
Rainfall model test and numerical analysis of seepage characteristics of dump slopeAbstract:
In order to study the variation law of slope seepage characteristics under rainfall conditions, the variation law of seepage field of different soil materials was analyzed by indoor rainfall model test in a double-stope dump, and the three-dimensional dump model was simulated by Flac3D software. The results show that under the action of rainfall, the response characteristics of moisture content, matrix suction and pore water pressure of soil slope model are significant, and the response priority of moisture content is the highest. Compared with Tianjiacun soil and ping soil, the permeability of Tianjiacun soil is stronger, and the expansion area of wetting front, saturation and pore water pressure is larger. The soil with strong permeability is easy to be destroyed by landslide, and the soil with weak permeability is easy to produce gully cracks. The matrix suction will continue to decrease, and the decrease of matrix suction will affect the shear strength index of soil, which is easy to cause landslide failure. According to the rainfall simulation of the three-dimensional model, rainfall has a great influence on the seepage characteristics of the slope, and rainfall leads to the continuous increase of pore water pressure in the discharge area, which may lead to landslides.
- 1
Research and Prediction of Coal Mining Machine Drum Load CharacterizationAbstract:
In order to study the roller load characteristics of coal mining machine and realize the load prediction, the cut-off coupling model is constructed by using the two-way coupling technique of discrete element-multibody dynamics (DEM-MBD) with the E2312 working face of Shanxi Gaohe Mine as the engineering object. The average torque error between numerical simulation and engineering experiment is small, which proves that the study of roller load by two-way coupling technique is reliable; using Hilbert-Huang trans-form (HHT), the time-frequency characteristics of each load are analyzed, and the time-frequency charac-teristics of the total load are studied under different motion parameters; based on the long-short-term memory (LSTM), the load from numerical simulation is used as the input sample to realize the load pre-diction. The results show that the study and prediction of load characteristics can be realized by using the DEM-MBD-HHT-LSTM model. Through the time-frequency characterization, it is found that each load under different motion states of the drum is discriminative and correlative; the accuracy of load prediction using the LSTM algorithm is in the order of total load, cutoff load, traction load, and lateral load. The study can provide a basis for the adaptive speed regulation strategy of coal mining machine.
- 1
Study on the growth and efficiency of mixed methane oxidation bacteria under different pH conditionsAbstract:
To further investigate the application basis of mixed methane-oxidizing bacteria in coal seam gas treatment, a survey was conducted on the highly active mixed methane-oxidizing bacteria in nature, and the growth and methane oxidation efficiency changes under different pH environments were studied. The dynamic contact characteristics of the bacterial solution on the surface of coal samples were then compared and analyzed. The results showed that the OD600 value of the bacterial solution increased by 20 times during the cultivation period when pH=6.75; it consumed 47.3ml of methane gas, and had the strongest growth and methane oxidation efficiency; the acid-base property could inhibit the growth of microorganisms, and the mixed bacteria could regulate the environmental acidity and alkalinity through their own metabolism, promoting the pH value of the bacterial solution to change in the direction of suitable growth; Compared with the bacterial solution with pH=6.75, the initial contact angle and equilibrium contact angle of the remaining groups increased by a maximum of 21.3% and 48.64%, indicating that a suitable pH environment can enhance microbial activity, promote its adsorption on coal samples, improve the contact ability of bacterial solution and coal samples, and provide theoretical support for the application of microbial technology in coal mines.
- 1
Analysis of the Mechanism of Partial Roof Falling in Weak Rock Stratum and Research on Filling MaterialsAbstract:
Weak rock mass after a long geological history of development, affected by a variety of factors, resulted in a weak rock stratum itself whose physical and mechanical properties were poor, easy to cause roof falling accidents, a threat to safety production. In order to solve the problem of partial roof falling in Songxian Shanjin gold mine, combined with the roof falling accidents in the mining process of Songxian Shanjin gold mine, we analyzed the mechanism of roof falling in weak rock drift, and put forward a new type of bag filling alternative. The index performance of filling materials was studied, the best ratio of foaming filling materials was determined, and the bag filling alternative was developed and perfected. The results show that this alternative in the field implementation process has a good filling effect, effectively solves the Songxian Shanjin gold mine roof falling problem, can make a good reference for similar conditions of mine supporting.
- 1
Study on the Dynamic Evolution Law of Provincial Coal Supply and Demand Patterns under the Carbon Peak Heterogeneous ScenarioAbstract:
The coal industry adjustment in each province under the carbon peak target has intensified the complexity of China's coal supply and demand pattern. It is important to analyze the trend of the evolution of China's provincial coal supply and demand pattern under the carbon peak heterogeneous scenario. By introducing the carbon peak regional heterogeneous influence factor, the provincial coal supply and demand SD model was constructed. And the historical data from 2013-2021 were selected as the input parameters to predict the coal resource consumption of China's provinces in 2025. Combined with the adjustment of coal production capacity, the coal demand gap and coal supply and demand pattern of each province in 2025 were calculated and discussed. The results show three points. Firstly, in 2025, China's coal consumption pattern will be shifted to the central and western parts of China. The concentration of coal consumption in the western part of the country will be increased, and the situation of "off-site transfer of coal consumption" will continue to exist. Secondly, the center of coal supply will gradually be concentrated in the areas of Shanxi, Shaanxi and Inner Mongolia, and the coal production capacity of the coal-rich areas needs to be strengthened. Thirdly, the contradiction of inter-regional coal supply and demand will gradually be eased, and the pressure of long-distance transportation of coal will be reduced. The contradiction between inter-regional supply and demand is gradually easing, and the pressure of long-distance coal transportation is decreasing, while the pressure of intra-provincial coal transportation is increasing. The results of the study are of some value in ensuring stable coal supply and energy security.
- 1
Study on the Cementing Properties and Fiber Strengthening Effect of Full-tailings Solid Waste-based Filling MaterialsAbstract:
Aiming at the problem of insufficient strength of filling body caused by high content of ultrafine particles in full-tailings of a gold mine, alkali-activated cementitious materials were prepared from mine solid waste, and polypropylene fibers with different lengths (0 ~ 18 mm) were added as reinforcing agents to study their effects on the liquidity and compressive strength of filling materials. The cementitious properties and fiber strengthening effect of the material were revealed from the microstructure by means of SEM. The results show that: (1) The surface of ultrafine particles in full-tailings is easy to form water film, which leads to the decrease of cohesive force, which is the main reason for the low strength of filling body. (2) With the increase of fiber length, the slump, fluidity and consistency of filling slurry decreased, and the bleeding rate increased. (3) The compressive strength of the filling body increases first and then decreases with the increase of fiber length. When the fiber length is 12 mm, the compressive strength of the filling body at 3 d and 28 d reaches the maximum value of 3.12 MPa and 8.05 MPa, which increased by 254.55 % and 41.48 % respectively compared with that of the same age without fiber.. (4) Fibers play a bridging and anchoring role in the matrix, effectively resisting and transmitting external loads, thereby increasing the compressive strength of the filling body. However, if the fiber is too long, it is easy to cause clusters and entanglements to form a weak surface, resulting in its strength reduction.
- 1
The study of leaching kinetics about Gansu Province quartzite by leaching with mixed acidsAbstract:
Acid leaching purification method is one of the most commonly used methods in quartz processing purification method. In order to explore the process and reaction mechanism of efficiently removing iron impurities from quartz,this paper takes a quartzite mine in Gansu Province as the research object, oxalic acid and hydrofluoric acid as leaching agent, explores the influence of different acid ratio, amount and acid leaching temperature on acid leaching effect, and deduce the dynamic model of mixed acid leaching quartzite mine. The results show that the acid leaching temperature has a great influence on the acid leaching effect, 85℃ is the best acid leaching temperature, 1%HF+10% oxalic acid is the best leaching agent, after acid leaching, the content of Fe2O3 quartz ore from 442μg/g concentrate can be reduced to 58μg/g, the iron removal rate can reach 86.74%.
- 1
Automatic control method for mining and transportation of open-pit mine cards based on 5G communicationAbstract:
Aiming at the extremely complex working environment of open-pit mines, the difficulty and long control time in the mining and transportation process of mining trucks, a research proposes an automated control method for mining and transportation of open-pit mining trucks based on 5G communication. Firstly, build a 5G communication system suitable for open-pit mines to collect real-time mining card operation data. Secondly, establish a kinematic model of the mining truck and use an improved A * algorithm (i.e. the improved A-Star algorithm, also known as the sparse A-Star algorithm, hereinafter referred to as the A * algorithm) to plan the reference trajectory of mining truck mining transportation, and introduce an adaptive preview strategy to determine the expected control rate. Finally, the particle swarm optimization algorithm is used to obtain the optimal preview distance and apply it to the trajectory tracking control of mining trucks, achieving automated control of mining and transportation of open-pit mining trucks. The experimental results show that the maximum lateral error of the mining truck in curved driving is 0.07 m, and the maximum heading angle error is 0.05 rad; The maximum lateral error during uphill and downhill driving is 0.13 meters, and the maximum lateral error during downhill driving is 0.12 meters; The maximum lateral error during obstacle avoidance driving is 0.1 m, the maximum heading angle error is 0.5 rad, and the maximum calculation time does not exceed 30 ms, indicating that this method achieves precise control of mining and transportation processes, reduces accident rates, and improves the safety and efficiency of open-pit mining.
- 1
INVESTIGATION ON THE MECHANICAL PROPERTIES ENERGY EVOLUTION RULES AND DAMAGE CONSTITUTIVE OF COAL-ROCK COMBINATIONS UNDER THE SITUATION OF ONE SIDE RESTRICTION LOADINGAbstract:
To explore the unstable fracture, energy evolution and damage mechanical behavior of coal-rock composites under load, rock-coal-rock composite samples with different height ratios are prepared and carried out multiple sets of unilateral compression mechanical tests based on digital image correlation (DIC) technology and a self-made "L" test mold. The mechanical properties and macro-fracture characteristics of coal-rock combinations are explored. Based on the thin plate buckling theory, a theoretical mechanical model of the coal wall is constructed and the coal wall stability of the coal-rock combination is analyzed. Furthermore, the dynamic evolution law of the energy of the assembly and its damage constitutive relationship are studied. The results that the stress-strain curve of the composite is mainly divided into four stages, namely, initial compaction stage, elastic stage, yield stage and post-peak failure stage. As the thickness of the coal seam increases, the peak strength and elastic modulus of the composite gradually decrease, while the peak strain gradually increases. The rupture of the sample mainly occurs on the free side of the coal seam. When the coal-rock height ratio is less than 1, the cracks penetrate the entire coal seam along the loading direction. However, when the coal-rock height ratio is greater than 1, the cracks transfer to the interface between the coal seam and the roof, causing small pieces of damage. The critical stress of coal wall instability increases with the increase of coal seam thickness. With the thickness of the coal seam increases, the energy storage limit of the coal and rock mass increases, while the energy release coefficient first decreases and then increases, and the height ratio equals 1 as the inflection point. According to the Weibull statistical distribution density function, the damage constitutive relationship of the coal-rock combination under the situation of one side restriction loading is constructed. The test results verified the feasibility of the constitutive relationship.
- 1
Research on Mine Pressure Manifestation Law of Dynamic Pressure Roadway with Multi-layer Hard Roof Plate and Control Technology of Deep and Shallow Hole Combination Blasting and Roof CuttingAbstract:
Aiming at the problem of difficult maintenance of multi-layer hard-roofed roadway due to the influence of mining of adjacent working face, taking 8104 transportation tunnels of Nianyan Coal Mine as the engineering background, comprehensively adopting the laboratory test, theoretical analysis, numerical simulation and on-site industrial test, etc., we studied the law of mineral pressure appearance and its mechanism of multi-layer hard-roofed roadway with dynamic pressure and put forward the technology of deep and shallow hole combination blasting to cut the roof to remove pressure, and analyzed the effect of controlling. The results show that: ① the deformation of the surrounding rock of the multi-layer hard roof roadway is mainly divided into three stages of slow deformation, rapid deformation and deformation tends to stabilize, and in the rapid deformation stage of the law of change of "step" type growth, the number of its "steps" and the near field of hard roof plate the number of layers; ② deep and shallow hole combination blasting cut the top, cut off the lateral cantilever structure of the low key layer, reducing the number of low key layer breakage caused by the dynamic load; at the same time shorten the length of the cantilever beams of the high and low key layer, reducing the static load applied to the section of the coal column, thereby jointly reducing the pressure of the adjacent dynamic pressure tunnel rock; ③ compared to the top of the non-cutting, shallow blasting, deep blasting and shallow and deep hole combination blasting and other 3 kinds of After cutting the roof in different ways, the average vertical stress on the side of the coal pillar was reduced by 14.8%, 8.9%, 29.7%, and after cutting the roof with deep and shallow hole combination blasting, the top plate collapsed more fully in the collapse zone, and in the fissure zone, the location of the rock fracture is the closest to the coal pillar, and the fissure generated by the overlying rock in the central part of the mining area is also more uniform; ④ After cutting the roof with deep and shallow hole combination blasting, the 8104 transportation tunnels in the neighboring working face of 8103 and the working face of 8104 were cut to the top, which is a good example of the combination of deep and shallow holes blasting, which can be used in the transportation tunnels. After the combination of deep and shallow hole blasting and roof cutting, the deformation of surrounding rock in 8104 transportation tunnels is less than 400mm after the influence of two mining activities in 8103 neighboring face and 8104 working face, which ensures the safe and efficient production of the mine.
- 1
Influence of feeding directions on the separation effect of flotation columnAbstract:
In order to improve the separation effect of the flotation column, the upward and tangential feed pipe were arranged on the flotation column at the same time, thus forming a flotation column combining the upward flow and rotating flow. The flotation tests were carried out in three feeding directions, namely, upward, rotating and combined upward and rotating, by batch flotation, and the flow field characteristics in the flotation column under different feeding directions were simulated by using ANSYS FLUENT software. As shown from the test results, under the same test conditions, the upward feed flotation has low ash content and good selectivity for the fine coal, and the tangential feed flotation has ash content of 71.66% and high flotation recovery for the tailings. The simulation results show that only the vortex is generated in the flo-tation column under the upward feeding, and the existence of the slurry sucking inner cylinder generates the upward flow at the bottom of the flotation column. Comparing the test and simulation results, it can be seen that the existence of eddy currents in the flotation column and the low turbulence intensity in the upper section of the column are the main reasons for the good selectivity in the direction of upward feeding; the reselection effect of the cone and the sucking inner cylinder at the bottom of the column, which is similar to the structure of the water-only cyclone, is the main reason for the increase of the tailings ash content in tangential direction and upward + tangential direction feeding.
- 1
Study on Influence of Vertical Shaft Impact Crusher Rotor Structure on Sand Production Rate and Its OptimizationAbstract:
In order to improve the sand production rate of the vertical shaft impact crusher, the influence of the rotor structure parameters on the sand production rate is explored, and the optimisation method of the rotor struc-ture is proposed with the target of sand production rate and rotor power. Firstly, a cumulative damage model of material particles under repeated impact is established; on this basis, a simulation model applicable to the crushing system of vertical shaft impact crusher is constructed, and the reliability of the simulation model is verified through crushing experiments; then, orthogonal tests and extreme difference analysis are used to re-veal the influence of rotor structure parameters on sand production rate and rotor power, and a mathematical model of the correlation between sand production rate and rotor power and rotor structure parameters is estab-lished; finally, an optimization method for rotor structure targeting sand production rate and rotor power is proposed using orthogonal tests. The mathematical model of sand production rate and rotor power with rotor structural parameters was established, and finally the structural parameters of the rotor were optimised using the mathematical model. The results show that when the diameter of the rotor is 836mm, the tilt angle of the cone is 38.9°, and the installation angle of the guide plate is 22.5°, the sand production rate is higher, and the power of the rotor will not be increased, which provides a theoretical basis for the improvement of the design of the rotor structure of the vertical shaft impact crusher.
- 1
Experimental study on reconcentration of rubidium-containing Lithium mica from a flotation tailings in Inner MongoliaAbstract:
The flotation tailings of a copper-zinc ore dressing plant contain a small amount of lithium rubidium minerals that can be comprehensively recovered, in which the content of Li2O and Rb2O is 0.337 % and 0.109 %, respectively. Due to the high content of argillized gangue minerals in tailings, it is difficult to enrich effectively by using common lithium ore collectors, and the separation is difficult. In this study, a new beneficiation process of "scrub-desliming-lithium separation-medium ore re-separation " and a new high-efficiency lithium mica collector CK-L were used to obtain a lithium rubidium concentrate with a Li2O grade of 1.64 % and a Rb2O grade of 0.39 %. The recovery of Li2O was 64.02 % and the recovery of Rb2O was 48.68 %. A good beneficiation index was obtained, which effectively recovered the lithium rubidium resources in copper and zinc tailings and improved the comprehensive utilization rate of resources.
- 1
Experimental study on slope erosion of surface moraine curing in Pulang copper mine under the action of heavy rainfallAbstract:
Natural caving method mining will form a subsidence area, and the slope of the subsidence area is very easy to be instability under the erosion effect of rainfall to form a underground debris flow disaster. In order to evaluate the effect of grout curing on the prevention and control of disasters in subsidence areas, an indoor model of subsidence pit-slope was established by using the principle of similar simulation. Through the artificial rainfall simulation and grouting simulation test to study the different soil slurry ratio under the moraine curing slope anti-erosion performance and runoff sediment production law, revealing the soil erosion process and slope instability mechanism. The results showed that the initial runoff production time and sediment intensity of rainfall increased linearly with the increase of soil-slurry ratio, while the sediment intensity of rainfall production decreased linearly with the increase of rainfall duration; The evolution of soil erosion can be divided into five stages: impact infiltration, water-filled softening, stripping and cutting, migration and crossing, and steady flow balance; Compared with the original moraine, the sediment consolidation effect and permeability resistance increased by 28.8 times and 11.3 times respectively when the soil-slurry ratio was 5:1, and the slurry curing effect was significant. This study can provide support for the disaster prevention and control of the subsidence areas in the surface collapse zone of natural caving mining method.
- 1
Risk assessment and prevention of underground debris flow in mine based on combination weighting-matter element exten-sion modelAbstract:
When the natural caving method is used for mining, the underground debris flow disaster is prone to occur under the comprehensive influence of material source, water source, geology and other factors. In order to prevent and control the underground debris flow of a copper mine in the plateau area, by analyzing the underground debris flow disaster chain induced by rain-fall-pulp-surface collapse-channel, a risk assessment index system including 5 first-level indica-tors and 22 second-level evaluation indicators was established. Firstly, the importance score of the index is collected from the experts in the field, and then the weight of the evaluation index is calculated by the combination of entropy weight method and analytic hierarchy process. The risk level of underground debris flow and the risk level of each evaluation index are evaluated by matter-element extension model. Finally, combined with the weight mean of each index and the evaluation results of the matter-element extension model index, the key prevention and control of high-weight and high-risk indicators are carried out. The results show that the risk level of underground debris flow in the mine is higher, among which the risk degree and weight of rainfall, moraine fragmentation, emergency disposal and other indicators are ranked higher. The proposed control measures can reduce the risk degree, thereby reducing the occur-rence or damage of underground debris flow, and providing effective guidance for the preven-tion and control of underground debris flow in the mine.
- 1
Application and Optimization of Banded Cemented Filling Mining in the First Mining Area of a Deep Phosphate MineAbstract:
In order to improve the low recovery rate and low safety of deep phosphate ores mined by traditional room and pillar stoping, a strip cemented filling mining method was proposed for a deep phosphate mine. Through comparative analysis by numerical simulation, the 6×12 m pillar, the construction parameters of the mine room and the mining steps of "one mining and one saving" were determined. According to the results determined by numerical simulation, mining tests were conducted in the first mining area. The test results show that the ground pressure is stable in the mining process and the construction safety is high. Compared with traditional room and pillar stoping, the recovery rate of banded cemented filling method is increased by 24.3%, which greatly improves the problem of "resource waste" caused by the low recovery rate of traditional room and pillar stoping. In addition, the banded cemented filling method has increased the profits of the enterprise by about 13%, which can provide some reference for the same type of mines.
- 1
Research on key parameters of slope enlarging engineering of near-horizontal compound coal seam open-pit mineAbstract:
In response to evolving internal and external conditions, open-pit mines may necessitate capacity enhancement to achieve greater economic benefits, and pit expansion stands out as a relatively economical means of increasing production capacity. Taking the pit expansion issue in composite coal seam open-pit mines as a starting point, this study analyzes three pit expansion modes: advanced, delayed, and synergistic. With a focus on the synergistic development mode, key parameters such as the length of the expansion working line, expansion angle, and com-pletion time are investigated. Given the production stripping ratio and hauling distance constraints, a method for determining the optimal working line length is proposed. Constrained by the expansion process and considering the expansion angle, an optimal calculation method for the expansion angle is derived by analyzing equipment layout patterns. Furthermore, based on on-site practicalities, an analysis of the expansion time is conducted. The research findings indicate that, using a composite coal seam open-pit mine as an engineering example, the optimal working line length post-expansion is determined to be 1000 m, with an expansion angle of 60° and an expansion time of 20 months. These results provide a theoretical reference for the implementation of pit expansion projects in open-pit mining operations.
- 1
Stability Analysis and Control Technology Research of Close-range Lower Coal Seam Roadway for Mining ExcavationnAbstract:
In order to study the stability of the roadway in the near-distance lower coal seam, the stability of the roadway in the near-distance lower coal seam was studied by combining theoretical analysis and numerical simulation with the problem of the roadway in the near-distance lower coal seam in the process of mining back of the 13 upper 06 face of the 31st mining area of Xin"an Mine, using the problem of the roadway in the 13 lower 06 face as the object of the study. Through numerical simulation of the range of influence of the support pressure of the quarry, the depth of the destruction of the bottom plate, and the deformation amount of the lower coal seam back-mining roadway, the range of the plastic zone, the change of the force of the anchor rods and cables, etc., to study the degree of mutual influence of the mining between the upper and lower coal seams, and to provide a basis for reasonably determining the safe distance between the upper coal seam back-mining and the roadway digging of the lower coal seams. The results of the study show that the dynamic pressure of the upper seam working face on the lower part of the lower seam working face tunneling influence the range of +30 ~ -30 m. It is recommended that when the pushing face of the hollow area is 30 m away from the head of the material roadway, the lower coal return roadway stops digging, and when the pushing face of the hollow area is -30 m away from the head of the material roadway, the lower coal return roadway resumes digging. During the cessation of digging, reinforcement should be carried out by means of monolithic pillars.
- 1
Intelligent GRA-KL-TOPSIS Evaluation Model for Coal Mine Production System Based on Game TheoryCHU Xinsheng1, SHENG Gaoyong1, ZHANG Haiyun2,3Abstract:
In order to make the intelligent evaluation of coal mine production systems more scientific, a GRA-KL-TOPSIS evaluation model based on game theory was proposed for the intelligent evaluation of coal mine production systems. Firstly, based on the theory of all factors and processes, an intelligent comprehensive evaluation index system for production systems was constructed from five aspects: fully mechanized mining, comprehensive excavation, transportation, comprehensive support, and safety monitoring functions; Secondly, the G1 method, improved CRITIC method, and game theory ideas are integrated to determine the comprehensive weight of indicators. Blind number theory is introduced to improve the expert indicator assignment processing method. The GRA-KL-TOPSIS method is applied to calculate the grey correlation closeness degree, achieving intelligent sorting and evaluation of production systems; Finally, taking three coal mines as examples for analysis, the results were compared with the VIKOR model evaluation results, and the intelligent differences of the subsystems were analyzed based on the radar graph method. The results indicate that the model can objectively evaluate the intelligence level of production systems, and the evaluation results are consistent with actual research conclusions, verifying the adaptability of the model.It can provide ideas for the quantitative evaluation of the intelligence level of coal mine production systems.
- 1
Multi-source Data Fusion Evaluation Model of Airflow Gas and Dust under Intelligent Control of Airflow in Fully Mechanized Excavation FaceAbstract:
At present, the airflow state of the air outlet under the total ventilation control mode of the fully mechanized excavation face cannot be dynamically changed in real time, which causes the problems of gas and dust disasters and pollution hazards. The multi-source data fusion evaluation and analysis of the complex ventilation environment safety state under the coupling of airflow gas and dust can provide a theoretical basis for the fine intelligent control of airflow and prevent the occurrence of disasters and accidents. The finite element calculation model of gas-solid coupling of airflow gas and dust is established by fluid mechanics and discrete element coupling method. The experimental platform of airflow monitoring and intelligent control test is designed and built to verify the model, and the key hidden danger location is simulated and determined. Combined with the requirements of coal mine specifications, the evaluation index system of three-layer structure is constructed by analytic hierarchy process, and the weight of each index is determined. A hybrid two-level fusion structure is used to analyze the optimal weighted data-level fusion and grey relational decision-level fusion, and an evaluation model with a rating of 5 is established. The fusion evaluation analysis of the fully mechanized excavation face of a coal mine in northern Shaanxi shows that under the extreme working condition of the shortest distance of 5m from the air outlet to the end face, the evaluation grade is safe when the diameter of the air flow intelligent control device is 1m, the horizontal deflection is 20 °, and the vertical deflection is 6 °.Compared with before and after the control, the gas and dust concentrations of wind speed at different measuring points are reduced to varying degrees, which verifies the effectiveness of the model.
- 1
Study on strain field evolution law of precast double-hole dali rock based on 3D-DICAbstract:
In order to study the effect of prefabricated pores on the mechanical properties of marble, two sets of marble samples with different pores were prefabricated for comparative testing. The first group was S-shaped, with two pores D1 and D2 of the same size, and the diameter of the pores was changed; The second group changes the diameter of a single hole D1 in a D-shape, while keeping the diameter of hole D2 unchanged. By combining uniaxial compression tests with 3D-DIC technology, the maximum principal strain cloud maps of marble at different stages were obtained, and the crack initiation and propagation laws during the failure process of marble with different pores were analyzed. The experimental results show that as the pore diameter increases, the peak stress and elastic modulus of the S-type specimen decrease sequentially, while the peak stress and elastic modulus of the D-type specimen first increase and then decrease; The cracks generated by the S-type specimen are mainly tensile cracks, strain concentration and cracks mainly occur near the D1 hole, while the cracks generated by the D-type specimen are mainly tensile shear cracks, and strain concentration and cracks mainly occur near the D2 hole; The failure mode of the S-type specimen is tensile failure, while the failure mode of the D-type specimen changes from shear failure to tensile failure as the pore D1 increases.
- 1
Study on stability mechanism and control of small coal pillar in inclined thin coal seam with composite roofAbstract:
In order to solve the problem of waste of large coal pillar resources and difficult protection of small coal pillar in gob-side entry driving, taking the 2104 working face of Huacaotan Coal Mine of HongNeng Coal Industry as the engineering test object, the reasonable width of small coal pillar under the disturbance of steeply inclined thin coal seam mining is studied by using the comprehensive research methods of theoretical analysis, numerical simulation and engineering practice. Through the two-way reinforcement of the anchor cable, the high-strength composite reinforcement support scheme of the trapezoidal roadway along the gob is given. The results show that the calculation formula of coal pillar width based on the limit equilibrium theory of rock mass, the coal pillar width value obtained by the actual conditions of the mine is greater than 3.35 m ; after the excavation of the roadway, the peak value of the lateral abutment stress will migrate to the deep part of the coal body, and its position will gradually move away from the goaf with the increase of the width of the coal pillar. The peak value of the vertical stress of the coal pillar will increase first and then decrease with the width of the coal pillar, and finally gradually stabilize. When the width of coal pillar is 5m, the deformation of roadway is stable, the deformation is small, the stress of surrounding rock is reduced, and there is no plastic zone in the center of coal pillar. The field practice shows that the deformation of the gob-side trapezoidal roadway with 5 m coal pillar and two-way fixed support of through-layer anchor cable is small, which meets the needs of safe production and has significant economic benefits.
- 1
Stability Analysis of Pillar and Goaf in Sanguikou Lead-zinc MineAbstract:
According to the shape distribution of pillar and goaf in Sanguikou lead-zinc mine, combined with the basic situation of the mine, engineering geological conditions, rock mechanics test results, etc., the stability of pillar in each middle section of Sanguikou lead-zinc mine above 580m is analyzed by theoretical analysis method, and the stability of goaf in each middle section is determined based on Mathews graphic method. At the same time, the typical pillar and goaf are calculated and analyzed by FLAC3D software. Finally, based on the above research results, the stability of mined-out area and pillar in the area to be recovered is comprehensively evaluated, and the pillar and mined-out area of Sanguikou lead-zinc mine are reasonably classified and classified comprehensively, which provides strong theoretical support for the safe and efficient mining of pillar in subsequent mines.
- 1
Study on Mechanical Characteristics of Backfilling Body under True Triaxial Compression and Unloading ConditionsAbstract:
For mines that adopt the backfilling mining method, the backfilling body is an important component of the underground stope. During the backfilling mining process of the first mining room and the pillars to be extracted after backfilling is completed, the backfilling body is disturbed and unloaded by the original geological stress and the excavation of the ore body.Based on the stress variation path during the backfilling and mining process mentioned above, conduct true triaxial compression and unloading experiments on the backfilling body, analyzing the instability and failure process of the backfilling body and the acoustic emission response characteristics, study the mechanical properties of backfilling body.The results indicate that:Under true triaxial compression conditions, the failure mode of the backfilling body specimen is mainly tensile failure, exhibiting better elasticity. The peak strength and elastic modulus increase with the increase of curing time and confining pressure.Under unidirectional unloading conditions, the peak strength of the backfilling body specimen decreases by about 17.74% compared to the peak strength under true triaxial conditions. The peak strength increases with the increase of confining pressure, the elastic modulus decreases with the increase of confining pressure, and the poisson"s ratio first increases and then decreases with the increase of confining pressure.Under bidirectional unloading conditions, the backfilling body specimen rapidly loses stability and fails, with a peak strength decrease of about 17.76% compared to the peak strength under true triaxial conditions. The peak strength, elastic modulus, and poisson"s ratio of the backfilling body specimen all increase with the increase of confining pressure.The backfilling body specimen undergoes greater deformation and lower failure strength under bidirectional unloading conditions than under unidirectional unloading conditions.
- 1
Effectiveness evaluation of the three-year special rectification action for work safety in non-coal mines and countermeasure suggestionsAbstract:
2022 is the final year of the three-year special rectification action for work safety in non-coal mines. To evaluate the completion of the three-year action tasks, the main work effectiveness of the three-year action was evaluated from six aspects using qualitative and quantitative methods: regulatory standard system, source governance measures, safety guarantee capabilities, major safety risk control, crackdown on illegal and irregular behaviors, and work safety situation. Based on a comprehensive summary of the national mine safety supervision bureau’s various departments, local emergency management departments, and relevant central enterprises’ work summaries on the three-year action, typical experiences and practices of national and local governments in the work promotion process were summarized. The problems in five aspects were analyzed: mining concepts, implementation of safety main responsibilities, safety infrastructure construction, regulatory supervision efficiency, and innovative methods and means. Four countermeasures were proposed to improve political positions, form long-term mechanisms, strengthen capacity building, and promote informationization and intellectualization construction.
- 1
Study on Reasonable Space-time Relationship of Opposite Mining in Close Distance Coal SeamsAbstract:
In order to determine the reasonable Space-time relationship of opposite mining in close distance coal seams, taking the 1503 working face and 11002 transportation trough as the engineering background, theoretical analysis and numerical simulation are used to analyze the distribution law of the advance abutment pressure of the working face in the process of the opposite mining and the evolution law of the floor stress of the goaf in the process of the backward mining. The theoretical calculation shows that the sum of the influence range of the advance abutment pressure of the 1503 working face and 11002 transportation trough in the opposite mining process is 131.01m, and the lag influence distance of the 1503 working face is 59.55m. The numerical simulation results show that the minimum advance influence distance between the 1503 working face and the 11002 transportation trough in the opposite mining process is 140m, and the minimum lag influence distance between the 1503 working face in the backward mining process is 60m. The theoretical calculation is basically consistent with the numerical simulation results. According to the results, a reasonable space-time relationship between 1503 working face and 11002 transportation trough is proposed to guide the safe production of the face.
- 1
Study on the Classification Performance and Flow Field Characteristics of Shuttle-Shaped Three-Product CycloneAbstract:
In order to lower the upper limit of coal slurry flotation size and reduce the amount of coal slurry into the flotation, a shuttle-shaped three-product cyclone with the upper overflow for fine-grained, the side overflow for intermediate-grained and the bottom flow for coarse-grained was designed. Taking the coal slurry below 1mm as the research object, the classification performance of the shuttle three-product cyclone and the ordinary cyclone were compared and tested, and the internal flow field was studied by numerical simulation. The test results show that the ash content of coarse particles in the side overflow of the shuttle three-product cyclone can reach the requirement of fine coal ash content, and the fine coal with a yield of 19.05% and an ash content of 8.67% can be obtained. The shuttle-shaped three-product cyclone has the characteristics of fine grading and can directly separate the coarse grains of fine coal, which can be used as the grading before flotation feeding to reduce the amount of flotation feeding and lower production costs. At the same time, the distribution rate of particle size in the upper overflow (greater than 0.25mm) is reduced by 4.13%, and the distribution rate of particle size in the underflow (less than 0.074mm) is reduced by 11%, and the cyclone overflow is running coarse, and the underflow is clamped with fines, which has been significantly improved. Flow field simulation results show that: shuttle-shaped three-product cyclone under the cone region of the zero velocity envelope outward, the cylinder region of the zero velocity envelope inward migration, which is to reduce the entrainment of fine mud in the underflow, the overflow run rough the root cause.
- 1
Mineral Processing experiments of a quartz diorite type high-mud low-sulfur gold oreAbstract:
Aiming at a quartz diorite type high-mud and low-sulfur gold mine in Northwest China, the contents of Au and S in the raw ore are 3.21 g / t and 2.61 %, respectively, and the content of easily floating or mudding gangue in the ore is as high as 40.50 %. Combined with the occurrence state and dissemination characteristics of gold in the ore, the beneficiation test was carried out. Finally, the full-size flotation process of one roughing, three scavenging and two cleaning was selected. Under the condition of grinding fineness of ? 0.074 mm accounting for 80 %, the interference of argillaceous gangue on the flotation of gold-bearing minerals was greatly reduced by optimizing the reagent system. The gold concentrate with Au recovery of 85.87 % and Au grade of 37.22 g / t was obtained, and the effective recovery of gold was realized.
- 1
Influence of Gas-Liquid Two-Phase Spray Atomization Parameters on Dust Reduction Effect of Fully Mechanized Excavation FaceAbstract:
In order to systematically study the influence of gas-liquid two-phase spray atomization parameters on the dust reduction effect of respirable dust in the fully mechanized excavation face, taking the excavation face of the 42207 auxiliary roadway of a mine in northern Shaanxi as the prototype, a geometric model of spray dust reduction in the excavation face under the condition of single press-in ventilation was established. The effects of droplet velocity, droplet size and droplet density on the dust reduction effect of respirable dust at the height of the breathing zone of the roadheader were systematically analyzed by numerical analysis methods. The results show that under the condition that the droplet size is 5×10-6 m and the nozzle mass flow rate is 0.005 kg/s, the dust reduction effect increases first and then decreases with the increase of droplet injection velocity. When the droplet spray velocity is 30 m/s, the dust concentration at the height of the driver"s breathing belt decreases from 1000 mg/m3 in the non-spray state to 168 mg/m3, and the dust reduction efficiency is 83.2%. Under the conditions of nozzle mass flow rate of 0.005 kg/s and droplet injection velocity of 30 m/s, when the droplet particle size is 9×10-7 m, the dust concentration is reduced to 148 mg/m3, and the dust reduction efficiency reaches 85.1%. With the increase of mass flow rate, the dust reduction effect showed a positive correlation, and when the droplet injection velocity was 30 m/s, the particle size was 9×10-7 m, and the mass flow rate was 0.02 kg/s, the dust concentration decreased to 102 mg/m3, and the dust reduction efficiency reached 89.9%. The research results can provide a reference for the optimization of the gas-liquid two-phase spray dust reduction system in the downhole excavation face.
- 1
Process Mineralogical Study and Selectability Analysis of a Polymetallic Copper Ore from BrazilAbstract:
In order to better separate and recover copper minerals and iron minerals in a polymetallic copper ore in Brazil, the mineral composition of the ore, copper ore The occurrence state, embedding characteristics and dissociation characteristics of iron minerals and iron minerals have been systematically studied. The results show that the copper grade of the ore is 0.8%, and the iron grade is 25.39%. The copper minerals in the ore are mainly bornite and chalcopyrite, with a small amount of chalcocite malachite. average, but the proportion of fine particles is relatively high, and the distribution rate of particle sizes below 0.02mm is 18.83%. The iron minerals are mainly magnetite, the content of hematite, siderite and ilmenite is small, and the particle size distribution of magnetite is relatively coarse, of which +0.074mm particle size accounts for 73.56%. Gangue minerals mainly include perillarite, mafic amphibole, biotite, plagioclase, magnesium-aluminum spinel, chlorite, grossular garnet, quartz, etc. When the grinding fineness is -0.074mm and accounts for 70%, the dissociation degree of the copper sulfide mineral aggregate is 66.94% and the single dissociation degree of magnetite is 81.97%. In summary, it is recommended to use the process of preferential copper separation and magnetic separation of tailings to recover iron for this ore to comprehensively recover copper and iron.
- 1
Development and application research of the information-based APP intelligent system for gas of coal mine drainageAbstract:
Gas drainage is the primary technical approach for managing gas in coal mines, and numerical simulation serves as a crucial tool for guiding the selection of gas drainage methods and evaluating their effectiveness. However, traditional modeling workflows and the mathematical models they require are highly complex, limiting the use of most simulation software to a select group of advanced users. To address this, the present study establishes a stress-seepage theoretical model for gas drainage. Grounded in the engineering practices of a specific mine in Shanxi Province, we construct both geometric and numerical models for gas drainage. Utilizing the COMSOL APP simulation platform, we have developed an intelligent system that integrates considerations for both coal layer and gas parameters. The research findings indicate that (1)The APP simulation"s predicted borehole flow decay patterns closely align with real-world observations, confirming the accuracy of our parameter optimization and the reliability of the numerical simulation approach (2) The intelligent system is user-friendly and allows for the optimization of various parameters, including drainage methods, drainage parameters, and permeability-enhancing measures. This will substantially reduce the actual workload and mitigate the risks associated with experience-based decisions, laying a solid foundation for future gas drainage planning and related research. The system holds significant engineering relevance and practical value.
- 1
Research on coal waste identification based on optimized VGG-16 network modelAbstract:
To address the problem of low efficiency and difficulty in sorting coal gangue under complex conditions, a coal gangue recognition model is built using the VGG-16 network. Explored the identification accuracy of the coal gangue recognition model and the influencing factors of the recognition environment. The optimization of VGG-16 coal waste identification model results in the following conclusions: (1) The accuracy rate of the optimized VGG-16 network model remains above 97%, and the image recognition time of single sheet coal gangue is 0.0697s, which shorts the image recognition time by 0.85%; (2) Under different environmental factors such as moisture, ash and dust, the accuracy rate of coal gangue identification model is above 95%, in which the influence of moisture on the recognition accuracy of the model reaches 2.01%. (3) In view of the co-occurrence characteristics of coal and gangue, the effective identification of coal waste is carried out under two complex situations of coal filling and coal carrying. The results show that the optimized VGG-16 network model has certain anti-interference ability, and can realize efficient and accurate identification of coal gangue under complex conditions, which provides theoretical basis and technical support for the intelligent separation of gangue in the future.
- 1
Study of Permeability and Pore Structure Evolution Patterns of Coarse-Grained Granite after Rapid CoolingAbstract:
The development of deep geothermal energy is an important way to realize the goal of "double carbon". Due to the difference in diagenetic environments, the mineral composition and fine structure of deep granites are quite different from those of shallow granites. In this paper, the coarse-grained granite of Luya Mountain, Shanxi Province, which represents a deep thermal reservoir, was selected to systematically study the evolution laws of permeability and pore structure in the mode of rapid cooling. It was shown that the threshold temperature for permeability of coarse-grained granite under unconfined and slowly heating conditions is 250°C. Multiple " heating-cooling" cycles can increase permeability and porosity, but the increase decreases as the number of cycles increases. Increase the heat treatment temperature and increase the number of "heating - cooling" cycle are conducive to the formation of oversized holes and large holes, when the heat treatment temperature reaches 400℃, the microporous start to generate. Both the physical properties and temperature sensitivity of the coarse-grained granite are favorable for the development of deep thermal reservoirs.
- 1
Causes and Solutions of the Reverse Curves’ Damage of Husab Uranium MineAbstract:
The reverse curve road of open-pit mine is the key section which affects the transportation. In order to improve the road condition level of the reverse curve road and solve the damage problems of sags crests and track rut-deept, this paper took the Hushan Uranium Mine in Namibia as the engineering background, respectively calculated and verified the subgrade strength, pavement strength and superelevation setting of each reverse curve road, and put forward corresponding management measures in combination with the production situation, achieved good practical results. The results showed that: The bearing capacity of 1026754Pa of calcium conglomerate subgrade on the surface is greater than its actual bearing of 825050.6 Pa, so there is no need to replace the subgrade of calcium conglomerate. The pavement strength can be represented by the pavement thickness. Based on the truck types, traffic volume and road design, the minimum pavement thickness of the reverse curve located on the pitheads of Z1S3, Z2S3 and the passageway of No.6 dump are respectively amended to 231.91m, 182.22m, 185.53m, and the pavement thickness of reverse curve located on the pitheads of Z2S2 do not need to be adjusted. The superelevation, speed and turning radius at each reverse curve should satisfy tanα=v2/Rg, and the speed should be remained at 10km/h, the superelevation of the reverse curve located on the heavy and empty lanes of Z1S3, the heavy lane of Z2S2, the heavy lane of Z2S3, the heavy and empty lanes of No.6 dump are respectively amended to 2.4：100, 1.6：100, 2.7：100, 3.3：100, 1.6：100, 2.5：100. The corresponding management measures are put forward from three aspects: strengthening maintenance, regulating driving and standard shovel. The results are conducive to improving transportation safety, service life,transportation efficiency and comprehensive cost, and can provide reference for the design optimization of reverse curve of open-pit mine road in the world.
- 1
Study on layout of mining roadway in close distance coal seam under residual coal pillarAbstract:
The layout and location selection of mining roadway in close distance coal seam under residual coal pillar is very important. Taking the layout of mining roadway in 21806 working face of lower coal seam in Qinglong Coal Mine as the research background，through the combination of theoretical analysis and numerical simulation, the maximum failure depth of 16# coal seam floor，the load of residual section coal pillar and the stress distribution of floor rock mass near coal pillar are studied. The layout and location of mining roadway in 21806 working face are determined by numerical simulation and empirical formula. The results show that：①The maximum failure depth of 16# coal seam floor is 8.6 m，and the uniform load of coal pillar is 10.5 MPa. ②With the increase of depth，the vertical stress peak position of the floor rock mass near the coal pillar is always located directly below the center of the coal pillar，the number of horizontal stress peaks changes from 1 to 2，and the position gradually moves from the center of the coal pillar directly below the goaf. The peak position of shear stress changes little. ③According to the stress characteristics of surrounding rock after excavation of mining roadway at different layout positions and the empirical formula，it is determined that the mining roadway of 21806 working face is arranged with 15 m internal dislocation.
- 1
The Construction and Application of Debris Flow Comprehensive Monitoring and Early Warning Platform Based on " Heaven-Earth-Well " Integrated TechnologyAbstract:
In view of the problem that many kinds of debris flow monitoring systems have been installed on the surface and underground of Pulang Copper Mine, but the data sources of each monitoring system are scattered, the types are various, the amount of data is huge, and the big data resources have not been fully utilized. By establishing a " sky-ground-well " three-dimensional monitoring framework that integrates the sky rainfall monitoring system, the ground displacement monitoring system and the underground channel monitoring system, the multi-level and multi-parameter real-time dynamic monitoring and early warning of debris flow disasters is realized. By using cloud computing and big data technology, a " sky-ground-underground " big data multi-parameter integrated monitoring and early warning platform is established to realize the intelligent early warning of underground debris flow risk, which is based on computer intelligent early warning and supplemented by manual early warning. The integrated management of debris flow monitoring in Pulang Copper Mine has changed the traditional multi-system and multi-person management mode, and significantly improved the intelligent and integrated level of debris flow monitoring and early warning management.
- 1
Research on the Technology of Predicting the Shape of Coal Seam Roof and Floor in Intelligent Fully Mechanized Mining FacesAbstract:
The prediction of the undulation state of the top and bottom plates of the coal mining face is one of the key technologies for intelligent mining of the working face. In order to solve the problem of large prediction error of the shape of the top and bottom plates of the coal seam, a prediction model of the shape of the top and bottom plates of the comprehensive mining face based on Convolutional Long Short-Term Memory Network (CONV-LSTM) is constructed on the basic principle of the memory cutting technology of the coal miner. Firstly, the shape features of the top and bottom slabs are extracted by using the spatial information of the direction of the coal miner in the adopted area and the temporal information of the direction of the return mining; then the CONV-LSTM model is constructed by using the extracted shape features; finally, the model is evaluated by using the shape data of the coal seam of the working face of Qinglongshi mine (5-20109), and the on-site test shows that the average error of the prediction of the shape of the top slabs is 0.036m, and the average error of the prediction of the shape of the bottom slabs is 0.036m. The results show that the CONV-LSTM model can accurately predict the shape of the top and bottom slabs, which can meet the demand for height adjustment of the front and rear drums of the coal mining machine in the project, and it is of great significance for the realization of the intelligent mining of comprehensive mining working face.
- 1
Study on Stability of Jiaoyishan Phosphogypsum stacking damAbstract:
With the development of large-scale tailings ponds, the stacking height of tailings ponds continues to increase, which makes the stability of tailings pond stacking dams extremely complex. The current stacking eleva- tion of the Jiaoyishan phosphogypsum slag yard is 942m, while the original design stacking elevation was 958m; The slag yard will undergo expansion and renovation, changing wet storage to dry storage, and increasing the original design stacking elevation by 40m, resulting in a design stacking elevation of 998m. In order to study the stability of the raised phosphogypsum slag yard accumulation dam, the following results were obtained through engineering survey data analysis, stability calculation, and numerical simulation: (1) When the elevation of the accumulation dam is 942m, the stability coefficient under normal and flood conditions meets the stability requirements, but when the drainage failure occurs, the stability coefficient is 0.98, and the dam body is highly likely to break. (2) When the elevation of the dam is 998m, the stability coefficient of the dry pile of phosphogypsum with a total slope ratio of 1:2.6 and 1:2.7 meets the specification requirements, and the dam body is safe; When the total slope ratio of dry pile phosphogypsum is 1:2.5, the dam body is unsafe; The stability of the accumulation dam increases with the decrease of the total slope ratio of dry pile phosphogypsum. (3) The plan of increasing the height of the pile dam in the form of dry pile in the Jiaoyishan phosphogypsum slag yard is feasible; The density of dry pile phosphogypsum should be taken as 1.32 g/cm3; The total external slope ratio of the accumulation dam should be 1:2.6; And it is necessary to strengthen the drainage measures of the dam body and monitor the infiltration line
- 1
Turning Platform into Change: Research on the Trigger Mechanism of Knowledge EmployeesAbstract:
Based on self-determination theory, organizational support theory and social exchange theory, this paper constructs a cross-level theoretical model of multi-level oriented platform leadership and knowledge employees" active change behavior with supportive organizational atmosphere and felt obligation for constructive change as mediating variables was constructed. A questionnaire survey to 26 knowledge teams (26 team leaders and 239 team members) in 15 national intelligent demonstration construction coal mines is conducted. The results show that multi-level oriented platform leadership, supportive organizational atmosphere and felt obligation for constructive change have a significant positive effect on knowledge employees" active change behavior. Supportive organizational atmosphere plays a cross-level mediating role between organization-oriented platform leadership and active change behavior. Felt obligation for constructive change plays a cross-level mediating role between individual-oriented platform leadership and active change behavior. Supportive organizational atmosphere positively stimulates felt obligation for constructive change, and the two play a chain mediating between organization-oriented platform leadership and active change behavior.
- 1
Study on the Influence of the Spatial Position of the Roadway in the No.3 Mine Area on the Size of the Surrounding Rock Loose CircleAbstract:
Aiming at the problem that the loose circle of roadway surrounding rock in Jinchuan No.3 Mine Area is not clear, which causes great trouble to the design of supporting parameters, this paper studies the loose circle size of 1330m level and 1438m level roadway in different spatial positions in Jinchuan No.3 Mine Area through field measurement and numerical analysis. It reveals the influence of horizontal arrangement direction and buried depth of roadway on the loose circle size of roadway surrounding rock in Jinchuan No.3 Mine Area. The results show that the different spatial positions of the roadway in the NO.3 Mine Area significantly influence the size of the loose circle of the surrounding rock of the roadway. The larger the horizontal layout direction of the roadway is, the larger the loose circle of the surrounding rock is. The amplification range of the loose circle of the surrounding rock in the range of 30° ~ 60° is more significant than that in the range of 0° ~ 30° and 60 ° ~ 90°. The increase of the loose circle of the roof and floor is higher than that of the two sides. The larger the buried depth of the roadway is, the larger the loose circle of the surrounding rock is. The variation curve of the broken area of the roadway surrounding rock with the buried depth is approximately linearly distributed when the buried depth is less than 500m. When the buried depth is more significant than 500m, the expansion range of the broken range of the roadway surrounding rock increases, and the overall stability of the roadway surrounding rock is destroyed. The research results can provide reference for the support design of the roadway, and can also provide reference for the design of the spatial position of the roadway in the roadway engineering.
- 1
Research on Path Planning of Unmanned Truck Based on Improved Gray Wolf AlgorithmAbstract:
In view of the shortcomings of conventional transportation path planning methods in complex terrain environments of open-pit mines, such as being prone to local optima, slow path convergence speed, and time consumption, proposed an improved Grey Wolf Algorithm for path planning of unmanned Truck. Considering the characteristics of terrain slope fluctuations in mining areas. A slope speed model is established to introduce the speed of the tramcar into the state transition rules for driving up and down slopes. A convergence factor combining sine and cosine transform is constructed to better balance the global and local search ability. The optimal grey wolf individuals are cross perturbed to enhance the ability of the wolves to jump out of the local optimum. The results show that the improved Grey Wolf Algorithm is better than traditional algorithms in terms of optimization ability, convergence speed, and stability, which is beneficial for the transportation operation of unmanned truck in open-pit mines in the construction of intelligent mines.
- 1
The Influence of Soil Cover Thickness and Step Slope Height and Slope Angle on the Stability of Mine Waste DumpAbstract:
The thickness of the reclaimed soil in the reclaimed slope and the geometries of reclaimed slope have a great effect on the stability of the reclaimed waste dump slope. The stability of reclaimed slope at Southern open-pit mine of State Power Investment Corporation Inner Mongolia Energy Co. Ltd is investigated in the present paper to study the influence of different reclamation thickness and the geometries of reclaimed slope on the stability of the overall slope combined with numerical simulations and field monitoring. The research shows that the thicker the soil cover on the upper part of the waste dump, the larger the bench slope angle and the higher the bench slope height, the worse the stability of the reclamation dump slope. The stability of slope and the reclamation effect of slope can be improved by changing the single-bench slope to multi-bench slope while keeping the angle and height of slope unchanged and meeting the requirements of reclamation construction technology. To ensure the effect of slope reclamation, the capacity of the dump, the safety of the construction operation and reclamation cost, it is recommended to have a bench angle of 24 °~28 °, the final slope angle should be about 26° and the soil cover thickness is 0.5m. It is of great significance for the reclamation of dump slope and the design of reclamation dump slope in open-pit mine.
- 1
Multi-objective Optimization Research on Structural Parameters of Stope under Complex Geological ConditionsAbstract:
In order to solve the problem that the stope structural parameters are difficult to meet mine multi- objective requirements of the safety, technology, economy, and so on under complex geological conditions. Based on the background of a certain gold mine, the optimization and trend analysis of stope structural parameters of the mining shrinkage method are carried out by combining rough set and response surface method. The main structural parameters that affect the stability, production capacity, and production cost of the mine stope were extracted by rough sets. Based on their generation rules, the optimal combination of structural parameters for the mine were obtained through step-by-step optimization, which including room length(50m), room width(3m), top pillar width(4m), bottom pillar width(4m), and interveningSpillar width(7m). According to the analyze by response surface method, it can conclude that the width of the mining room and the interaction factor between the width of the mining room and the width of the top pillar are the greatest impact structural parameters to the stability of stope; The length of the mining room is the greatest impact structural parameter to the production capacity of stope; The interaction factors between the width of the bottom pillar and the width of the bottom pillar and the width of the inter pillar are the greatest impact structural parameters to the production cost of slopes. After applying the above stope structural parameters, the number of annual safety accidents was reduced by 68%, the average production capacity of stope was increased by 27%, and the production cost of a ton of ore was reduced by 19%, which achieved safe, efficient, and economical production. Thus, providing a new approach for optimizing the design of stope structural parameters under similar conditions.
- 1
Effect of Fly Ash Collected by Electrofilter on Cementation Filling Properties of Lead and Zinc Tailing SandAbstract:
In order to investigate the influence of electrically enhanced fly ash (EFA) on the filling performance of lead-zinc tailings, the flowability of the slurry was analyzed by slump and rheological measurements. Additionally, the changes in filling body strength were determined, and the variation of filling body porosity was analyzed using low field nuclear magnetic resonance (L-F NMR) technology. The results demonstrate that the optimal EFA to ordinary Portland cement (OPC) ratio is 4:6. At this ratio, the slump of the slurry is 27.0 cm, and the yield stress and plastic viscosity decrease by 16.60 Pa and 0.0258 Pa·s, respectively. Under the optimal EFA ratio, the filling body strength significantly increases, with the highest strength observed at 28 days of curing age, reaching 2.76 MPa. Meanwhile, L-F NMR testing indicates a significant reduction in porosity in the later stage of the filling body under the optimal EFA ratio. At 28 days, the total porosity of the filling body is 12.50%, with the porosity of micropores, transition pores, mesopores, and macropores being 5.51%, 4.48%, 1.37%, and 1.14%, respectively. In summary, the improvement in the filling effect of lead-zinc tailings is attributed to the optimized EFA ratio, which improves the particle size distribution of the slurry and reduces its yield stress and plastic viscosity. Furthermore, it enhances the internal structure of the filling body, lowers the porosity, making the structure more compact, and increases the strength of the filling body.
- 1
Characteristics and Control Techniques of Gas Emission in Short Range Coal Seam Group Mining under Complex Geological ConditionsXu Gang 1, 2, Niu Hangyu 1Abstract:
Under the conditions of close range coal seam group mining, significant changes in the thickness and spacing of adjacent coal seams lead to strong imbalance in gas emission, which has become a challenge for gas control in working faces. Taking the 2502 working face of Shaozhai Coal Mine as the research object, the failure depth and evolution law of the underlying coal rock fracture zone were studied through theoretical analysis and numerical simulation. Based on the analysis of the gas migration law of adjacent coal seams, a calculation method for the gas emission amount in close range coal seam group mining under complex geological conditions was proposed, and the gas emission amount was predicted and divided into regions. Finally, based on the prediction results of the gas emission amount, A targeted approach is proposed to extract gas from adjacent layers and goaf by using the method of "drilling through the bottom of the floor, drilling through high-level boreholes, and inserting pipes into the goaf". The number of boreholes through the bottom of each area is determined based on the amount of gas emitted from each area, achieving regional management of gas extraction. The results show that the 2502 working face of Shaozhai Coal Mine can be divided into three gas emission areas, with a gas emission volume of 34.74 m3/min in Area I; The gas emission amount in Area II is 14.66 m3/min; The gas emission amount in Region III is 29.86 m3/min. After the gas extraction and sub regional management, the bottom plate through layer drilling has achieved good drainage effect, with stable return air flow and gas concentration in the upper corner, without any sudden changes, effectively ensuring the safe extraction of the working face.
- 1
Research and Application of a Digital Platform for Safety Risk Management and Control of All Employees in a MineAbstract:
Aiming at the problems of poor flow of safety production data, single system, backward safety management mode and other problems existing in the process of traditional mine safety informatization construction, the theoretical idea of "risk classification and control, list management", the introduction of artificial intelligence, big data and other technologies, the analysis and research of the overall framework of the overall framework of the mine full-employee risk control system, and the research and design of platform key technologies such as the management of mine risks and hidden dangers, dynamic monitoring of the operation process, and the overall framework of the mine full-employee risk management system, were carried out. It has carried out research and design of key technologies of the platform, such as the management of hidden risks in mines, dynamic monitoring of work processes, and the overall framework of the mine risk control system. It has realized the coverage of the whole process of all-employee safety business, formed a safety information platform with comprehensive functions of safety business management, risk control and monitoring of the whole production process, and cultivation of employees" safety behaviors and habits, and promoted the overall improvement of the safety management level of the mines.
- 1
Effect of 300~150 ℃ cyclic heat treatment on the tensile strength of graniteAbstract:
In order to reveal the evolution law of physical properties and tensile strength of granite after cyclic heat treatment at 300-150℃, the natural water absorption rate and longitudinal wave velocity changes of granite after different heat treatment cycles were measured, and the Brazilian splitting test was carried out, during which acoustic emission was used to monitor the acoustic characteristics of the failure process. The results show that: (1) After cyclic heat treatment at 300-150 ℃, the natural water absorption rate of granite increases, the change rate is 0.25~ 0.35%, the longitudinal wave velocity decreases, and the attenuation rate is 1132.3~1199.6 m/s; (2) The tensile strength of granite decreases exponentially with the increase of heat treatment times, and the lowest is 13.21 MPa at room temperature -300 ℃ -room temperature treatment, while the tensile strength at 300-150℃ cyclic heat treatment is higher than that at room temperature -300 ℃ -room temperature treatment. (3) Compared with room temperature condition, the time from loading to failure of granite after cyclic heat treatment shows a decreasing trend, and the accumulated energy of acoustic emission and the peak ringing number appear before the peak load. (4) After cyclic heat treatment at 300-150 ℃, the accumulated acoustic emission energy and wave velocity damage variables monitored during the failure of granite are opposite with the change of the number of cycles. The relevant test results can provide reference for the physical and mechanical evolution behavior of granite under a certain temperature cycle.
- 1
Research on Gas Extraction Technology of Interception Borehole in Close-Distance Coal Seam groupsAbstract:
In order to solve the problem of gas control in close-range coal seam groups, taking a working face of Du’erping Coal Mine as the research object, the development of overburden fracture after mining is simulated. According to the gas extraction mechanism of close distance coal seam group, FLUENT was used to study the gas migration before and after the arrangement of ‘ roof high-level borehole + floor interception borehole’ in the goaf, and the extraction effect and the volume fraction of CH4were compared and analyzed. The results show that the height of overburden caving zone is 16 m, and the height of fracture zone is 58 m. When the roof high-level boreholes are arranged in the vertical distance of 38.5 ~ 57.25 m from the roof, the horizontal position is within the range of 20 ~ 50 m from the return air roadway, and the floor interception boreholes are arranged 5 m below the floor and 10 ~ 15 m from the side of the return air roadway, the CH4 volume fraction in the upper corner of the working face can be reduced to 0.32 %, and the extraction efficiency can be improved. Based on this, the gas extraction technology of interception borehole in test working face is put forward and applied, and good gas control and extraction effect are achieved.
- 1
Study on Damage Properties and Constitutive Model of Different Fiber Mixed PhosphogypsumAbstract:
For enhance the strength and toughness of the phosphogypsum cemented body, the experiment was carried out the incorporation of fiber to improve the physical strength characteristics of phosphogypsum cementation was conducted, and the polypropylene fiber content was 0%, 0.5%,0.75%,1%,1.25% of phosphogypsum-based composite cement body, respectively the damage rule of was studied.Research finding that: (1) with the raise of polypropylene fiber incorporation amount, the compressive strength and peak strain augment to a certain extent, and the compressive strength and elastic modulus both enhance first and then cut down, and the optimal admixture is 0.75%, it shows that the reasonable amount of polypropylene fiber is very important to affect the compressive strength of phosphogypsum cement body.(2) The stress-strain curve of cemented body test specimen with different fiber content has similar morphology. The difference between the stress-strain curve of the mixed fiber cement body and the ordinary phosphogypsum cement body shows that the incorporation of fiber can ameliorate the peak residual strength and toughness of the phosphogypsum cemented body, which can obviously improve the compressive strength of the phosphogypsum cemented body.(3) Based on the strain equivalence theory and statistical damage theory, five kinds of damage correction coefficients are introduced, and the uniaxial compression damage constitutive model of fiber mixed phosphogypsum cemented body is deduced, and the uniaxial compression damage constitutive equation and damage evolution equation of phosphogypsum cemented body under different fiber dosage are established.(4) By comparing the theoretical curve with the test curve, we discover that each curve has similar forms and the agreement between the two is good at the peak, which shows that the theoretical research model has a certain number of reference worth for the analysis and study of phosphogypsum cemented body with different fiber content.The research results of this thesis can supply some theoretical support for the application of phosphogypsum matrix composite material in the solid waste cement filling site.
- 1
Study on Stability Monitoring of Bottom Structure under the Influence of Ore DrawingAbstract:
In order to study the stability of the bottom structure under the influence of natural caving drawing, the stress and microseismic monitoring results of the mine ground pressure monitoring system are used to analyze the influence of the ore drawing amount on the stress of the pillar of the bottom structure, and the spatial and temporal distribution of the fracture event of the bottom structure during the drawing process is studied. The stress monitoring results were verified by Microseismic activity parameters. The results show that the unbalanced time and space of ore drawing operation will lead to stress concentration in the local rock mass of the bottom structure, and the stress distribution of the bottom structure can be adjusted by continuous and stable ore drawing in the stress concentration area. Microseismic activity parameters can be used as reference to evaluate the possibility of ground pressure disaster of the bottom structure during ore drawing, and the stress concentration area can be delineated by the microseismic monitoring system, so as to make up for the deficiency of single point monitoring coverage of stress on a large scale.
- 1
Temporal and Spatial Evolution of Microcracks in Surrounding Rock of Roadway Triggered by Blasting DisturbancesAbstract:
Roadway failure triggered by repeated blast disturbances is a common phenomenon in deep metal mines. Investigation on the development of microcracks in the surrounding rock around the roadway is helpful in optimizing the support parameters. In this study, the numerical simulation and experimental study of the dynamic expansion of microcracks were performed by using discrete element software and acoustic emission (AE) monitoring technology, respectively. The temporal and spatial evolution characteristics of microcracks in surrounding rock around the roadway subjected to combined action of static loading and blasting disturbance under different lateral pressure coefficients were investigated. The results show that the direction of the principal stress affects the initial spatial distribution of the excavation damage zone and the dominant crack types. In addition, blast disturbance mainly promotes the expansion and penetration of the microcracks, aggravating the damage to the roadway. Especially, where the ratio of the length of the waveform to the span of the roadway is approximately 1, the degree of microcrack extension in the sidewalls facing the blast is significantly greater than that in other areas. In the absence of radial stresses or small radial constraints, the blast disturbance stress waves can easily lead to tensile fracture in the direction of the principal stress and the sidewalls facing the blast. Therefore, when determining the support measures for deep roadways, the differences in fracture characteristics caused by principal stress and blast disturbance parameters should be considered comprehensively.
- 1
Highly Efficient Low Dilution Upward Cut and Fill Mining Method for Complex Metal Ore DepositsAbstract:
Aimed the difficulties such as high ore dilution and poor stope stability exist in the mining of complex metal deposits, the vein-type low-waste mining process with "Z"-shaped and airbag pre-occupancy method and efficient low-dilution upward cut and fill mining method were proposed. Based on a certain gold mine in Inner Mongolia, this mining method is explored through field investigations and laboratory experiments to study stope structural parameters and the overall structure and dimensions of the pre-occupancy airbag. The research results show that the rock mass quality index (RMR) for the experimental mining section in the mine ranges from 51 to 63, corresponding to a stope span limit of 5.5m to 10.5m. The design of the pre-occupancy inflatable airbag's overall structure is determined, the working pressure of the inflatable airbag is calculated to be 0.2MPa, with a load-bearing capacity of 0.5MPa. The relationship between the blasting compensation space and the rock fragmentation coefficient is calculated, determining a reasonable span of the pre-occupancy inflatable airbag as 2.5m. Based on this foundation, industrial field tests were conducted with a stope size of 4m in height, 5.5m in width, and 20m in length. The results of the industrial test show that the production capacity of the two-step stope reaches 150t/d, with an ore recovery rate of 94% and an ore dilution rate of 4.8%. This method has achieved efficient and low-dilution mining for this type of complex metal ore deposit.
- 1
Study on the Fracture Law and Stability Control of Interlayer Overburden Rock in Multi-coal Seam MiningAbstract:
To study the complex and difficult to control issues of interlayer roof breakage in multi-seam coal mining, with a certain multi-seam coal mine in Shendong as the research background, comprehensive research methods including theoretical analysis, on-site monitoring, and numerical simulation were used to investigate the characteristics and migration rules of interlayer roof breakage in multi-seam mining. Based on the cantilever beam theory, the amount of interlayer roof movement in the lower mining layer during multi-seam mining was calculated, and the field monitoring data were compared and analyzed against the theoretical values. The 3DEC simulation was used to study the interlayer roof movement and breakage characteristics of multi-seam mining at different mining distances. Finally, the coal wall anchor + interlayer roof anchor net anchor rod reinforcement support technology was proposed. The results show that the 3DEC simulation results are used to calculate the fracture development height of the interlayer overburden; in the process of multi-seam mining, it is easy to adopt downward mining, and the spacing between upper and lower coal seams is 20-40 m. In the process of multi-coal seam mining, the movement of interlayer overburden rock increases first and then decreases. The roof movement of the coal wall anchor cable + interlayer overburden rock anchor net bolt reinforcement support technology is reduced by about 65 %, and the support effect is achieved. The research results are of great significance to the control of multi-coal seam mining and roof stability.
- 1
Research on safe and efficient construction technology of deep crushing station in Jinchuan II mining areaAbstract:
The construction of the underground crushing station at the 610 m level in the Jinchuan II mine area was confronted with complex geotechnical conditions around the refuge, poor rock stability and high rock density, etc. Combining the results of the on-site engineering research and the preliminary geological survey, the construction plan was determined to adopt the up-slope relay guide method, which is to guide the refuge from the large piece of road to the top of the refuge and then to complete the refuge by layers and zones of brushes, the technical parameters of the construction plan are as follows. The technical parameters were: the excavation section was 4 m x 3.75 m, the slope of the refuge was 22°26′51″, and the heights of the first, second and third layers were 4.2 m, 3.5 m and 4.7 m respectively. A four-pronged system, including ventilation, hair removal, power supply and auxiliary equipment, was used to ensure that construction of the chamber would proceed smoothly. Finally, the technical parameters, construction sequences and processes were optimized and adjusted to ensure that they were compatible with the adjacent works. The results of this project show that the design is reasonable and the stability of the sidewalls of the refuge is good, with no cracking of the support body or concrete support layer.
- 1
Study on Optimization of Bench Slope Angle of High Slope in Open-pit Mine Based on Stereographic Projection AnalysisAbstract:
Aiming at the problem of balance between slope safety and economic benefit in open pit mines, a method of bench slope Angle optimization based on the stereographic projection analysis is proposed. Taking the high slope of an open-pit mine as the research object, the slope failure modes under the combination of different bench slope angles and superior joint fracture surfaces were studied based on the stereographic projection analysis method. The slope stability coefficients under different failure modes were calculated by the limit equilibrium method, and the optimal value of bench slope angles was obtained. The integral stability of the slope under the angle of the optimal bench slope angle is analyzed by strength reduction method of finite element. The results show that the slope has different failure modes under different bench slope angles. The optimized bench slope angle is 65°, which meets the requirements of safety standard under the three load combinations. The final slope angle of the stope obtained by this optimization method is 49°, and the ore recovery of the stope slope is increased by 282,000 m3 compared with the current stope slope, and the slope is in a stable state, which verifies the reliability of the method.
- 1
Experimental study on reverse flotation desiliconization of iron ore based on new low-temperature resistant collectorAbstract:
In response to the problems of high flotation cost and high energy consumption in the current heated reverse flotation process used by Guanbaoshan Concentrator, a new low-temperature resistant collector KDB-1 developed in the laboratory was used for reverse flotation experiments at low temperatures (10-16℃). The experimental results show that under the conditions of a pulp pH value of 11.0, a collector KDB-1 dosage of 1500g/t, an inhibitor of caustic starch dosage of 700g/t, and an activator of calcium oxide dosage of 1000g/t, a closed circuit flotation test with one coarse, one fine, and three sweeps can be conducted on the flotation feed of Guanbaoshan Iron Mine. Excellent indicators such as iron concentrate grade of 66.50%, iron recovery rate of 87.64%, and iron tailings grade of 20.51% can be obtained. Research has shown that the new low-temperature resistant collector KDB-1 can effectively achieve energy conservation, environmental protection, cost reduction, and efficiency enhancement while achieving efficient sorting.
- 1
Intelligent mining safety assurance system and key technology for coal seams with extremely complex conditionsAbstract:
In view of the problems existing in the intelligent construction of coal seams with extremely complex conditions, this paper introduces the progress of intelligent safety guarantee technology in coal mines in China, expounds the key technologies of gas prevention and control, mine fire, water disaster control and personnel and equipment collaborative scheduling in coal seams with extremely complex conditions, and establishes the safety guarantee system of intelligent mining working face. It is emphasized that the basis of intelligent mining is to establish an accurate geological perception model. Combined with the engineering practice of Huaibei mining area, the solution to the problem of intelligent safety guarantee of coal seam under extremely complex conditions is put forward, which mainly includes geological perception, gas, water disaster, fire risk prevention and big data platform equipment personnel scheduling. Based on high-density three-dimensional seismic precise geological support technology, high-efficiency directional drilling technology for high-gas coal seams, mine water disaster protection technology, mine fire online monitoring and early warning technology and overall scheduling architecture of mine personnel and equipment, mine safety risks and production costs are reduced. It provides a reference for engineering practice under similar conditions and provides a technical path for building an intelligent mining safety guarantee system for extremely complex coal seams.
- 1
Experimental Study on Flow Field Characteristics of Deep Cone Thickener Feedwell under Different Feed Flow RatesAbstract:
The flocculation and settlement behavior of all tailings particle groups in the deep cone thickener feed well is the key link and the primary premise of solid-liquid separation. Based on the acrylic similarity model, particle imaging velocity measurement technology and floc tracer technology, a visual test system of flow field characteristics in the feedwell of deep cone thickener was designed, and the flow field of all tailings particle groups under the in-situ flocculation system of the feedwell under different feed flow rates was visualized. The results show that with the increase of feed flow, the relative retention rate and turbulent kinetic energy decay rate gradually increase and tend to be stable, indicating that there is a limit optimal value of feed flow. The feed flow rate is too small, the initial kinetic energy of the feed is insufficient, the whole tailings can not fully spiral movement in the feed well, and the flocculation effect is poor. When the feed flow rate is too high, the turbulent kinetic energy at the outlet of the feeding well is still large, which destroys the completed flocculation particle group, and the flocculation effect is poor.
- 1
Study on the Influence of Subsidence Area Backfilling in the Eastern Section of Zhangfushan Mine on Surface Deformation.Abstract:
The sublevel caving method without sill pillar often results in surface subsidence, cracking, and deformation in the surrounding areas, which affect the safety of nearby buildings. Backfilling the subsidence area is a commonly used method to control deformation of the surrounding rock and soil. Studying the deformation control effect of backfilling in the subsided area helps protect buildings in key areas. Based on the deformation monitoring data before and after the backfilling of the subsided area in the eastern area of Zhang Fushan mine and the results of discrete element calculations, the deformation control effects of backfilling on different surface areas and the effects of backfill amount on strain and horizontal deformation were analyzed. The results show that backfilling in the subsided area has a good restraining effect on the footwall, but has a smaller effect on the hanging wall as well as east and west ends of the ore body. When the backfill amount reaches a certain level, it has a significant deformation control effect. The research results can provide guidance for the treatment of subsided areas.
- 1
Study on Coal Pillar Size Retention of Gob-side Entry in Inclined Extra-thick Coal Seam Under GoafGu Shi-tan, 丁宁, 王国良, 刘志尧, 马腾, 陈森军
Abstract:
In order to study the problem of coal pillar size setting in gob-side entry of inclined extra-thick coal seam under goaf, the pressure relief law of goaf floor on inclined extra-thick coal seam and the mechanical model of lateral abutment pressure of inclined extra-thick coal seam under goaf are obtained by combining theoretical analysis with numerical simulation. It is concluded that the reasonable width of section coal pillar should be greater than 11.9 m or the sum of section coal pillar and roadway width should be less than 11.9 m. According to the theoretical calculation, five groups of numerical models with different coal pillar widths were set up to analyze the vertical stress and horizontal displacement of coal pillars with different widths after the excavation of gob-side entry in inclined extra-thick coal seam under goaf, and the reasonable coal pillar width was determined to be 6 ~ 8m. Combined with the theoretical calculation and numerical simulation conclusions, under the premise that the roadway width is 5m, the reasonable section coal pillar width should be less than 6.9m, and it is recommended that the section coal pillar width should be 6m.
- 1
An approach on Tunnel Face Segmentation against Lidar Point Clouds based on Spatial Gradient Filtering and K-means ClusteringAbstract:
Aiming at the problem that the existing surface filtering methods might partially apply to the point cloud segmentation of the tunnel face of mineral tunnels, this paper proposes a segmentation method for the tunnel face based on spatial gradient filter and K-means clustering. The process removes the connection between the tunnel face and the tunnel wall based on a spatial gradient filter, followed by the k-means clustering that completes the tunnel face segmentation. Finally, used the AABB bounding box to screen the filtered out point cloud to fill in the interior holes of the tunnel face caused by over-segmentation. Against four sets of Lidar point cloud data that cover varying tunnel surfaces, point density and detection angle offsets, the current work conducts a parameter sweeping study to locate the optimal hyper-parameters, with which the precision, recall rate and comprehensive evaluation index F1 of the current work reach 97.80%, 98.98% and 98.38%, respectively. The experimental results show that the proposed algorithm can effectively segment the tunnel face out of complex surface topographies, confirming its high precision, maneuverability and robustness.
- 1
Research on the deformation mechanism and reinforcement technology of surrounding rock in the "three soft" coal seam mining roadwayAbstract:
In response to the serious deformation of the surrounding rock of the "three soft" coal seam roadway, taking the 1307 working face return air roadway as the engineering background, the mechanical characteristics and deformation failure mechanism of the roadway surrounding rock were mastered through a combination of indoor experiments, numerical simulations, and industrial experiments. The roadway reinforcement technology was proposed and applied. The results show that: ① the mineral composition of the surrounding rock of the tunnel is relatively high, and the development range of cracks in the surrounding rock of the tunnel under the original support scheme is large, the force on the anchor cable is close to the breaking load, and the deformation of the surrounding rock is severe; ② Revealed the mechanism of unreasonable support methods and poor mechanical properties of surrounding rock as the deformation and failure of tunnel surrounding rock, clarified that the two sides and bottom plate of the tunnel are key parts for reinforcement control, and proposed a control strategy of "full length bonding anchoring+side reinforcement+bottom plate reinforcement"; ③ We constructed numerical calculation models for different support schemes, obtained the displacement and plastic zone distribution characteristics of the surrounding rock under different reinforcement schemes, and ultimately determined the reinforcement parameters with good tunnel control effect; ④ After the application of tunnel reinforcement technology, the maximum deformation of the surrounding rock of the tunnel is 156 mm. Compared to the original support, the displacement of the roof, floor, and two sides of the tunnel has decreased by 84% and 87%, respectively. The surrounding rock of the tunnel has been stably controlled.
- 1
Exploring the Characteristics of the Impact of Mining on Overburden Movement in Thick and Extra Thick Coal Seam GroupsAbstract:
In this paper, the 4-5 working faces, (9-15) 06 working faces and (9-15) 08 working faces of Meishuigou Coal Mine in Xinjiang are taken as the research objects, and UDEC numerical simulation software and on-site monitoring data are used to explore the movement characteristics of the overlying strata of the coal seam and the impact of overlying strata movement on the mining of the lower coal seam during the mining process of multi-layer thick and extra thick coal seams. Research has found that the movement of overlying strata exhibits a clear "weak upper and strong lower" characteristic under the control of multiple key layers; The control effect of the key layer causes the overlying rock movement to exhibit a clear "low medium high" gradual development feature from bottom to top; During the mining process of the upper coal seam, the hard sandstone above is less prone to fracture and damage, and the movement of the overlying rock is incomplete, resulting in significant fracture and damage of the high and middle rock layers during the mining process of the lower coal seam, with a greater release of elastic energy. Therefore, in the process of mining the upper coal seam, reasonable and effective roof control measures such as pre cracking are developed to avoid significant energy release during the mining process of the lower coal seam.
- 1
Seismic dynamic response of goaf in near fault coal seam mining and its impact on surfaceAbstract:
In order to study the seismic dynamic response and its impact on the surface of goaf near fault coal seams, taking Luyukou Coal Mine in Shanxi Province as the engineering background, based on engineering wave theory, a three-dimensional numerical model was established using MIDAS GTS NX finite element software combined with geological environmental conditions. Nonlinear time history analysis method was used to calculate and analyze the acceleration response law of free site and near fault coal seam mining site The law of displacement variation and the distribution of plastic zone. The research results indicate that under the action of shear seismic waves, the presence of goaf will reduce the peak horizontal acceleration above it and change the surface dynamic response characteristics; Cracks will form between the goaf and the fault in a very short period of time, and the expansion of the cracks will cause the goaf to continue to fall and worsen, causing surface deformation; Compared to free sites, after mining, the exposed surface rock layers of the footwall quickly develop cracks and connect along the weak layer, resulting in greater displacement response and causing disasters such as surface collapse and landslides. The research results can provide a certain reference basis for the scientific prevention and control of coal mine seismic dynamic disasters.
- 1
Strength and micro mechanism of tailings substrate improved by cement-BPSFAbstract:
In order to solve the problem of natural soil scarcity for ecological restoration of mining slopes, the low-alkali cement and bagasse-PAM-SAP-acid fertilizer (BPSF) were used as modifiers to improve the properties of tailings, production of vegetation substrate for ecological restoration of mine. Through L9(34) orthogonal design, shear tests were conducted on samples of different ratios of vegetation substrate during the initial age. The initial shear strength was used as the assessment index, and the optimal ratio of substrates was determined through range analysis; conduct shear tests on samples of the optimal ratio of substrate at different ages to study the effect of curing age on the shear strength of the substrate;using thin section identification, scanning electron microscopy and X-ray diffraction to analyze the strength characteristics and micro mechanism of tailings substrate improved by cement-BPSF synergy. The results showed that the most significant factors affecting the strength of the substrate are the contents of cement and bagasse, the early strength of substrate increased with the contents of cement and bagasse; With time increase, the friction angle of substrate began to decrease after reaching its peak, and the failure mode of substrate has changed from ductile failure to brittle failure. The tailings substrate improved by cement-BPSF has the soil-like structure and strength for plant growth. The optimum ratio of substrate is cement 12% , bagasse 4% , PAM 0.6% , SAP 0.15% , acid fertilizer 1.2%.
- 1
Evaluation of Rock Burst Level Based on Combination Weighting Cobweb Grey Target ModelAbstract:
As a major challenge in high stress underground engineering, rock burst strength evaluation has become an important research topic. In order to effectively predict rock burst disasters in underground rock mass engineering, this paper proposes a rock burst strength evaluation model based on combination weighting spider web grey target. Firstly, select the rock brittleness coefficient σc /σt. Stress coefficient σθ /σc. The elastic deformation energy index Wet and rock mass integrity coefficient Kv are used as evaluation indicators for rock burst strength. Select the classification criteria for rock burst levels, calculate objective and subjective weights using Critic method and ordinal relationship analysis (G1) method, and determine comprehensive weights based on game theory combination weighting method. Based on the spider web grey target theory, establish a range set of target distance ranges for different rock burst levels, and then evaluate the rock burst level based on the target distance size of the indicators to be evaluated. In order to better verify the accuracy and reliability of the model, a case study was conducted on the rock burst of the Zhongnanshan Highway Tunnel project using the model. The research results indicate that the rock burst evaluation results based on the combination weighting cobweb grey target model are basically consistent with the actual rock burst level, and the rock burst level evaluation model has good practicality and reliability.
- 1
Research on Quantitative Evaluation Model for Maturity of Intelligent Filling Control SystemCHU Xinsheng1, SHENG Gaoyong1, ZHANG Haiyun2,3Abstract:
In order to evaluate the operational status of the filling intelligent control system more scientifically and reasonably, the regret theory based on bounded rationality was introduced, and a comprehensive evaluation model for the maturity of the filling intelligent control system based on game theory regret theory was established. Firstly, based on the maturity theory, 16 influencing factors were selected from four aspects: slurry preparation, pipeline transportation, strength monitoring, and system visualization, and a multi-level comprehensive evaluation system for the maturity of the intelligent control system for mining filling was constructed; Secondly, interval analytic hierarchy process, entropy weight method, and game theory are used to determine the comprehensive weight of indicators. By calculating the total evaluation value, the maturity level of the evaluated object is determined; Finally, the established game theory regret theory model is applied to determine the maturity level of an intelligent control system for iron ore filling, and the results are compared with the fuzzy comprehensive evaluation method and the matter element extension model. The results show that the maturity level of the intelligent control system for filling in the mine is level IV, and the conclusions of the three evaluation models are completely consistent. This verifies the applicability and reliability of this model in the maturity evaluation of the intelligent control system for filling, and can provide reference for system evaluation and improvement.
- 1
Design of Magnetite Sorting Scheme Based on Visual LocalizationAbstract:
Aiming at a certain enterprise"s magnetite pre-selection equipment, which has the problems of inaccurate positioning of ore and overlapping of ore edges, and is difficult to realize continuous sorting, a magnetite pre-selection scheme based on visual positioning is designed. The scheme uses the ore magnetic signal threshold segmentation, visual positioning, watershed algorithm segmentation to obtain the ore category and the location of the center point, and design the sorting control strategy to achieve qualified ore sorting. Experimental results show that this scheme can realize accurate magnetite positioning and edge overlap segmentation and continuous sorting of qualified ores, with a average sorting efficiency of 53.83%; the average processing time of a single image is 0.216s, and the sorting time of a single ore is about 20ms, which meets the demand for rapid sorting.
- 1
Influence of Slope Angle Change on Slope Stability State and Final Boundary of Open-pit Coal MineAbstract:
With the continuous development of deep resources mining, the contradiction between ensuring slope safety and improving economic benefits in open-pit coal mining is becoming increasingly prominent. This paper takes the final boundary, which has a significant impact on the economic benefits and geometric form of the mine production, as the entry point, adopts the floating cone removal method to optimize the final boundary of the open-pit mine, builds an open-pit slope landslide risk assessment model based on the reliability theory to evaluate the stable state of the slope, and explores the influence of steepening slope on the stable state and final boundary of the slope. At the same time, the optimum boundary and slope Angle are determined. The case study shows that the slope steepening method is mainly affected by production economic parameters and occurrence conditions of ore body. The slope steepening Angle of open pit mine will increase the boundary profit continuously, and the economic profit will increase by 65.2 million yuan on average for every 1° increase of slope, but at the same time, the slope instability probability increases exponentially. The probability of instability increases by 50% for every 1° slope increase.
- 1
Analysis of The Current Situation and Strategic Planning of Fluorite Resource Utilization in ChinaAbstract:
Fluorite is an important non-metallic strategic mineral resource. With the rapid development of technology and society, the strategic position and value of fluorite have become increasingly significant, and it is widely used in various fields such as fluorine chemical industry, metallurgy industry, information technology, new energy, etc. Due to the limited amount and uneven distribution of fluorite resources, there is a gap in the development and utilization level of fluorite resources. It is crucial to solve the supply-demand contradiction between fluorite resources and fluorite related industries and make strategic planning for fluorite resources. In order to explore the strategic planning of Chinaese fluorite resources, an investigation was conducted on the distribution status, application fields, beneficiation status, and import and export situation of fluorite resources. The strategic position and important value of fluorite resources were elucidated, and suggestions for the development of Chinese fluorite industry were proposed.Through strengthening exploration efforts, utilizing digital technology to establish a fluorite resource database, promoting the coordinated development of upstream and downstream fluorite enterprises, promoting the integration of fluorite resources, and strengthening scientific research, we ensure the strategic reserve and supply of fluorite resources, and promote the green development, coordinated development, and sustainable and healthy development of Chinese fluorite industry.
- 1
Study on the Performance of Cement-based Solid Waste Filling Materials in Different Hydration EnvironmentAbstract:
In order to study the influence mechanism of different hydration environments on the mechanical properties and microstructure of cement-based solid waste filling materials, six kinds of hydration environments were designed, including standard constant temperature and humidity curing (C1), bagging constant temperature and humidity curing (C2), natural air curing (C3), water curing (C4), 30 ℃ curing (C5), and 40 ℃ curing (C6), to explore the failure patterns of test blocks under different hydration environments, and X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) were used to analysis the mechanism of hydration products of filling materials. The results show that the curing temperature is a key factor affecting the rapid increase of early compressive strength of the filler, which can accelerate the dissolution-reconstruction-condensation reaction of silica-aluminate raw materials, increase the output of hydration products AFt and C-S-H gel, and the products grow rapidly and interweave to fill between the pores of the aggregate, forming a dense three-dimensional structure. However, the high temperature led to the uneven distribution of hydration products, which blocked the dissolution of colloidal active ions and affected the later strength improvement. Humidity determines the development of late strength of the filled body, which can provide water molecules for the hydration reaction, and the compressive strength size is ranked as C6＞C4＞C1＞C5＞C3＞C2 when the age of maintenance is 28 d.
- 1
Research on the Control Technology of Top Cutting and Pressure Relief Surrounding Rock of the Filling Body next to the Combined RoadwayAbstract:
In response to the unclear bearing characteristics and blind parameter selection of the composite filling body under the condition of hard roof cutting, the 90203 return air roadway is taken as the research object. Theoretical analysis, numerical simulation, and on-site experiments are used to study the stress characteristics and rock pressure behavior of the composite filling body under different width and layer height conditions after roof cutting. The results indicate that: 1) a stacked layer plate model is established to analyze the stress state and deformation of the filling body under top cutting conditions, and a calculation formula for the reasonable parameters of the combined filling body after top cutting is provided; 2) As the height of the composite filling layer increases, the overall bearing capacity of the filling body undergoes periodic changes, resulting in a stress trend of first increasing and then decreasing; As the width of the filling body increases, the adaptability of the filling body to the surrounding rock changes, resulting in a non-linear decrease in stress; 3) Practice has shown that the combined filling body in the mining stage of the 90203 working face is basically undamaged, and the maximum displacement of the top and bottom plates is 307mm and 319mm, both within a controllable range. This study can provide certain reference significance for the engineering application of mines with similar conditions.
- 1
Multi-dimensional coupling realm ore pillar safety stability analysisAbstract:
Based on the open-air to underground mining, this paper calculates the minimum retention thickness of the ore column in this realm to be 40m based on theoretical calculation and engineering analogy method, and analyzes the influence of underground blasting vibration under the condition of the retention thickness of the column, and the FLAC3D numerical simulation software was used to analyze the displacement and stress of the ore column during the mining process.. Based on multi-dimensional calculation results show that the blasting vibration caused by the underground blasting operation has little effect on the boundary ore column, which is within the controllable range. The deformation of the central rock mass of the realm ore pillar has been in a small fluctuation, and a certain degree of stress concentration phenomenon, its maximum compressive stress and tensile stress are less than the strength of the rock mass itself, and the stability of the realm ore column at 40m is better, which can meet the needs of mine safety production.
- 1
Study on Source Location and Spatial-Temporal Evolution Law of Roof in No.2 Mining Area of Jinchuan CompanyAbstract:
Microseismic picking is a key factor in accurately locating potential hazards in mining production. However, signal acquisition in complex underground production environments is susceptible to noise interference, posing significant challenges to traditional picking algorithms. To overcome the difficulties of applying traditional picking techniques to low signal-to-noise ratio and complex waveform acoustic emission (AE) events, this paper proposes an automatic picking method called WSA (Wavelet-STA/LTA-AIC picker). This method uses discrete wavelet transform (DWT), short-time average/long-time average (STA/LTA) ratio method, and Akaike information criterion (AIC) to combine the temporal and spectral characteristics of P-wave arrivals and obtain accurate P-wave picking. Field test results from the Jinchuan mining field show that compared to other picking methods, this method has the smallest average positioning error and standard deviation, and has better accuracy and robustness, providing more accurate and reliable positioning results in complex mining environments.
- 1
Damage and Compression-Shear Fracture of Single Fractured Red Sandstone under Freeze-Thaw CyclesAbstract:
The western cold region is rich in mineral resources, and more and more projects are built in the cold region, and the freeze-thaw cycles have a non-negligible effect on the fractured rocks in the project. In this paper, the TDS-300 freeze-thaw experimental machine was used to carry out freeze-thaw cycle tests on single fissure red sandstone, and the number of cycles was set to 0, 20, 40 and 60. The uniaxial compression test was carried out on red sandstone after freeze-thaw damage using SHT 4206 servo universal experimental machine apparatus, and the freeze-thaw damage characteristics of red sandstone were detected with the help of nuclear magnetic resonance (NMR) technology. The test results showed that the elastic modulus, mass, peak strength and porosity damage variables of red sandstone showed different degrees of increase with the increase of the number of freeze-thaw cycles. By NMR technique, it was found that the spectral area increased with the increase of the number of freeze-thaw cycles, while small pores developed slowly, medium pores developed more rapidly in the early stage than in the later stage, and the number of large pores increased the most. In addition, the larger the number of freeze-thaw cycles, the more the white spots in the NMR map spread from the edge to the center, and the damage area gradually increased and deepened toward the interior. Based on fracture mechanics, the pressure-shear fracture criterion for single-fissure red sandstone was established under the coupled freeze-thaw-load action, and it was clarified the relationship equation between the pressure-shear coefficient and the number of freeze-thaw cycles and fracture dip angle. The study provides theoretical support for exploring the mechanical behavior and mechanism of fractured rocks in cold regions and is of great practical importance for disaster prevention and mitigation.
- 1
Numerical Simulation Study on Creep Rule of Borehole in ExtractionAbstract:
In order to study the influence of creep on borehole mass, study the stress-strain change law around the hole, establish the gas-containing coal flow coupling model considering creep, and explore the influence law of Poisson"s ratio and Young"s modulus on gas pressure and drilling creep around the hole. The results show that the change of the gas pressure gradient around the hole decreases with the increase of Poisson"s ratio and Young"s modulus, the larger the two, the more conducive to the extraction of gas in the coal seam; With the increase of the[ ] horizontal distance from the borehole, the displacement size of the coal rock is reduced first, then increased and then decreased; The displacement of the borehole wall increases with the increase of Poisson"s ratio,decreases with the increase of Young"s modulus, and stabilizes with the passage of time; The smaller the Poisson"s ratio and Young"s modulus, the more obvious the equivalent creep strain; the Young"s modulus has more influence on borehole creep than Poisson"s ratio.
- 1
Application of Microseismic Monitoring Technology in the Collaborative Mining Process of Caving and Filling MethodsAbstract:
The West NO.2 mining area of Longshou Mine in Jinchuan is a lean mineral resource area. The mine was originally designed as a double middle section downward layered cemented filling method for mining, but in the later stage of production, due to mining cost reasons, the upper section was changed from filling method to sublevel caving method, and the lower continued to be mined using cemented filling method. As a result, a complex situation of simultaneous mining operations between the upper section caving method and the lower section filling method occurred in the mining area. Due to the significant differences in the activity and distribution characteristics of ground pressure between the collapse method and the filling method, in order to ensure the stability of the entire West NO.2 mining area, a three-dimensional wrapped microseismic monitoring network has been established to achieve comprehensive monitoring coverage for the upper and lower sections of the mining area. At the same time, a user-friendly microseismic safety monitoring platform has been independently developed, achieving functions such as automatic cleaning, high-precision positioning, and automatic warning of microseismic signals. Real time dynamic monitoring of the overall stability of the West NO.2 mining area using the established microseismic system. The analysis of microseismic monitoring results shows that during the collaborative mining process of the two mining methods, the upper caving method stope excavation route is in a stable state, the roof cemented filling body of the stope naturally collapses to form a cover layer, and the lower section cemented filling stope is in a stable state as a whole.
- 1
Study of High-Pressure Pulverized Coal Gas-Solid Two-Phase Jet Dynamics and Coal Breaking CharacteristicsAbstract:
In order to further strengthen the ability of high-pressure jet to break coal and reduce energy consumption, combined with the theory of in-situ physical crushing fluidized mining, a high-pressure pulverized coal gas-solid two-phase jet coal breaking method is proposed. Based on the DPM discrete phase model, the flow field structure characteristics and the acceleration law of pulverized coal in gas-solid two-phase jets were clarified. Subsequently, the RHT constitutive model of coal is constructed, and the coupling model is established by DEM-FEM method, which explores the internal stress wave propagation and dynamic damage law of coal during erosion, and compares and analyzes the energy consumption and coal breaking effect of gangue water jet and pulverized coal jet. The results show that with the increase of jet pressure, the fluid state changes from overexpansion to underexpansion, and the Mach disk structure of the flow field becomes more and more obvious. Increasing the jet pressure can increase the impact energy of the pulverized coal jet, which is conducive to strengthening the internal stress wave effect of coal, prolonging the effective action time of stress wave, aggravating the damage of coal, and coal is more easily damaged by shear form. With the increase of propagation distance, the stress wave will have a certain degree of frequency dispersion and amplitude attenuation, and the attenuation rate increases with the increase of jet pressure. Under the same impact speed, the macroscopic damage of pulverized coal jet to coal is more serious, and its erosion rate is 1.78 times that of gangue water jet, and the corresponding specific energy consumption is only 56% of that of gangue water jet, which can show better coal breaking characteristics. The research results can provide some theoretical support for the application of gas-solid two-phase jet coal breakage.
- 1
Optimization Analysis of Mining Span Parameters for Two-step Segmented Rock Drilling Stage Open Pit and Subsequent Filling Method Based on Critical Weighting MethodAbstract:
The structural parameters of the mining site have a significant impact on the safety and economic efficiency of underground production operations in mining enterprises, and it’s crucial to choose reasonable parameters. Taking a certain iron mine as the engineering background, based on the Mathews stability chart calculation results, six sets of two-step mining site span plans were designed, and corresponding simulation models were constructed using MIDAS/GTS and FLAC3D for numerical calculation. Finally, based on the Critical weighting method, mining effect parameters and filling material costs were introduced as cost based evaluation indicators, and the production capacity of the panel was used as economic evaluation indicators, A comprehensive evaluation of the safety and cost-effectiveness of six sets of span parameter schemes was conducted, and the results showed that: 15m×17m panel span parameter scheme has the highest score in comprehensive evaluation and can better meet the safety production requirements in on-site industrial trials.
- 1
Washing Water Calculation model of Long-distance ofUltra-deep Shaft Filling PipeAbstract:
Clean filling pipeline can reduce the resistance along the paste transportation and avoid the occurrence of pipeline blockage and pipe burst accidents. In order to study the influence of pipeline length, filling times, flow rate and slurry mass fraction on the amount of washing water, a self-made filling pipeline cleaning experimental device was used to carry out pipeline cleaning experiments. The results show that there is a proportional coefficient I between the amount of washing water and the volume of the washed pipe, which is about 0.87 ~ 1.60. The amount of pipe washing water increases linearly with the increase of pipe length, increases exponentially with the increase of filling line, decreases exponentially with the increase of flow rate, and decreases linearly with the increase of slurry mass fraction. The flow rate of pipe washing water has the most significant effect on the unit consumption of pipe washing water. When the flow rate is less than 0.55 m / s, the shear stress of pipe washing water is less than the yield stress of deposited paste, and laminar flow dominates. Based on the proportional coefficient I, the calculation model of pipe washing water consumption constructed by the model experiment is extended to the industrial prototype, and the reliability of the model is verified by the measured data, with an error of less than 10 %.
- 1
Research, Development and Application of Intelligent Inspection Robot for Safety Hazards on The Dam Face of Tailings PondsAbstract:
Timely detection of slotting and gulch of tailings dams is key to ensuring the safety of tailings dams. Taking the tailings dam as the engineering background, an intelligent inspection robot for dam surface slotting and gulch on the tailings dam surface was developed, utilizing technologies such as tracked chassis systems and automation control. For target detection, an improved YOLOv5m network model YOLOv5m-ECA was proposed, by inserting convolutional block attention modules into the backbone network and neck network of YOLOv5m. Application research was conducted in unmanned inspection operations on tailings dam surfaces. The results show that the improved YOLOv5m-ECA algorithm improves the model's accuracy, mean average precision, and F1 score by 12, 2.3, and 3.6 percentage points, respectively, compared to the previous improvement. Compared with the performance of four mainstream object detection algorithms, YOLOv5m-ECA demonstrates stronger overall performance and is easily deployable on mobile detection equipment, making it more suitable for slotting and gulch detection on dam surfaces. Field applications have shown that this method can replace manual operations for unmanned inspection of tailings dam surfaces, providing an intelligent solution for rapid disease detection on dam surfaces. The detected disease positions correspond to the actual dam surface positions, demonstrating practical significance and application value.
- 1
Muscle Fatigue Analysis of Monorail Crane Driver Based on Surface Electromyogram SignalAbstract:
As a kind of underground transport locomotive in coal mine, the working environment of monorail crane will cause problems such as the comfort of underground workers. In order to analyze the fatigue status of the main muscles of monorail crane drivers, the EMG test was carried out on 16 muscles easily tired, and the integrated EMG and root mean square values of the signals were extracted. Combined with time domain analysis and multivariate nonlinear regression analysis, the muscle fatigue characteristics were analyzed with integrated EMG value and root mean square value as independent variables and fatigue degree as dependent variable. The results show that the muscle fatigue of the driver during boarding and alighting is much greater than that during walking. In the process of locomotive operation, because the driver needs to step on the accelerator pedal with his right foot to control the locomotive, the rectus femoris, biceps femoris, gastrocnemius and soleus muscles of the driver's right lower extremity muscles have fatigue, and the gastrocnemius fatigue is the largest. This study provides data reference for the muscle fatigue analysis and cab layout optimization of monorail crane drivers during operation.
- 1
Study on Bearing Test and Stress Condition of Grouting Steel TubeAbstract:
In order to satisfy the support resistance of roadside support in gob-side entry retaining and the easy of operation of construction in coal mine, grouting filling material replaces concrete as steel pipe filler, and the grouting steel tube is proposed to carry out roadside support. In order to study the bearing capacity and stress distribution of grouting steel tube , the bearing capacity of short column specimens with diameter Ф = 159 mm, wall thickness h = 8 mm, length l = 500 mm and long column specimens with diameter Ф = 159 mm, wall thickness h = 8 mm, length l = 1200 mm were tested. The numerical simulation analysis of grouting steel tube was carried out by ABAQUS software. The results show that : Compared with the traditional concrete-filled steel tube piers, the bearing capacity of grouting steel tube can reach the level of concrete-filled steel tube piers of the same grade. The deformation of grouting steel tube under impact load appears layered folding, and the maximum deformation is in the middle position. The maximum bearing capacity of long column grouting steel tube reaches 2400 kN, which is a good choice for roadside support and other engineering support loads in coal mine. The rib guard plate structure of the upper and lower pressure plates has high bearing capacity, which can effectively protect the upper and lower pressure plates to maintain the stability of the pier column. The bending deformation of the long column pier appears in the middle position. In the field application, the reduction of the bearing capacity of the pier column after the column length is further lengthened should be considered, and the stability of the grouting steel tube should be improved by strengthening the middle of the long column or increasing the diameter of the grouting steel tube. The research results are of great value for mastering the bearing capacity of grouting steel tube and the next promotion and application.
- 1
Study on the Distribution Characteristics of 1438m Horizontal Peripheral Rock Loosening Circle in Jinchuan Three Mining AreaAbstract:
In response to the impact of differences in surrounding rock loosening zones in the support of tunnels in the third mining area of Jinchuan, a 1438m horizontal tunnel was taken as the research object, and on-site testing of the loosening zone was conducted using acoustic testing method. The thickness of the two sides of the loosening zone in different surrounding rock tunnels was obtained. A numerical calculation model for the loosening zone in different surrounding rock tunnels at the 1438m level was established, and the distribution characteristics of different surrounding rock loosening zones and the influence of rock mechanics parameters on the thickness of the loosening zone were studied. The research results show that the thickness of the loose zone at the 1438m section bottom plate of Jinchuan No. 3 Mining Area is the largest, followed by the top plate, two sides, and arch shoulder, and the thickness of the loose zone at the bottom corner is the smallest; The thickness of the loose zone in mixed rocks is generally larger at different positions, followed by ultrabasic rocks, and the thickness of the loose zone in amphibolites is generally smaller at different positions; The thickness of the loosening ring decreases exponentially with the increase of cohesion and internal friction angle. The rate of decrease in cohesion slowly decreases, and the rate of decrease in internal friction angle slowly increases. The research results can provide a theoretical basis for the design of support schemes for surrounding rock tunnels in the three mining areas.
- 1
Study and Application on Rheological Model of Graded Fine Particle Tailed Mortar under Constant Shear RateAbstract:
The rheological properties of tail mortar are important parameters for filling design. Based on the specific working conditions of a gold mine in Shandong, constant shear rate loading tests were conducted to study the rheological properties of fine-grained tail mortar (hereinafter referred to as tail mortar) using slurry structure dynamics theory. A constitutive model of tail mortar under constant shear rate was established, and constant shear rates of 2s-1, 20s-1, 80s-1, and 180s-1 were obtained using linear programming theory, The specific expression for the constitutive model when the mass concentration of tailings slurry is 74%. The research results indicate that during the constant shear rate loading test, the shear stress on the tail mortar gradually decreases with time and eventually stabilizes; The constitutive model of the tail mortar is an exponential function, and the determination coefficients R2 of the theoretical model curve and experimental results are 0.9897, 0.9785, 0.9612, and 0.9583, respectively. The model curve has a good fit with the experimental results, and the research results can provide theoretical guidance for the filling design of similar mines.
- 1
Study on the strength mechanism and key influencing factors of fiber reinforced tailings pasteAbstract:
The addition of fiber is beneficial to enhance the strength and toughness of the tailings filling body and improve the stability of the paste filling structure in the goaf of deep wells. However, there are few studies on the strength mechanism and key influencing factors of fiber reinforced tailings fill in long-term curing situation. In this paper, tailings filling samples are prepared by using an iron ore tailings, sulphoaluminate cement and water, and the effects of fiber content, length and type factors on the strength of reinforced tailings filling body with 120 days curing are tested and analyzed. The mechanism of fiber reinforced tailings filling body is theoretically analyzed. The following conclusions are obtained: (1) Based on Mohr-Coulomb strength theory, when the fiber content is low, the tensile force of the near-horizontal fiber section is the internal cause of fiber reinforced tailings filling body; (2) With the increase of fiber content, the change characteristics of uniaxial compressive strength of tailings filling samples are closely related to the fiber length. When the fiber length is small, it shows the change characteristics of increasing first and then decreasing; When the fiber length is large, it shows a change process of decreasing first and then increasing, then decreasing or decreasing first and then increasing; (3) With the increase of the length of polypropylene fiber, the change process of uniaxial compressive strength of the sample is first increased and then decreased, then increased and then decreased; When the fiber content is relatively high, with the increase of the length of polypropylene fiber, the change of uniaxial compressive strength of the sample shows a process of first decreasing, then increasing and then decreasing; (4) The type of fiber has a significant impact on the uniaxial compressive strength and failure mode of the tailings filling body. Compared with polypropylene fiber, glass fiber is more beneficial to improve the uniaxial compressive strength of the tailings filling body, but it is relatively weak in improving the toughness, and the degree and scope of damage are also larger. The research results have certain reference value for the filling of underground goaf mixed with fiber tailings paste and the gob-side entry retaining in deep mines.
- 1
Research on Ming Pressure Prediction of Working Face Based on Informer Neural NetworkAbstract:
In order to effectively improve the problems of low mine pressure prediction accuracy and insufficient generalization ability in the working face, a time-series prediction model of the mine pressure is established based on the Informer neural network model, and the historical mine pressure data collected by hydraulic supports is taken as input to realize the prediction of the mine pressure for a period of time in the future . The established model is based on the mine pressure input sequence information extracted by the ProbSpare self-attention mechanism, which can capture the long-term dependence of the input sequence and model the complex nonlinear relationship between the influencing factors, thereby improving Informer model prediction accuracy. The mine pressure data of the XV1307 working face of Chengzhuang Mine is used for model training and testing, and a comparative experiment with particle swarm optimization BP neural network (PSO-BP) and Long Short Term Memory network (LSTM) was established. The results show that: for the prediction of mine pressure in the next 1-4 days, the root mean square error (RMSE), mean absolute error (MAE) and coefficient of determination (R2) of the Informer neural network are all optimal, and a good prediction effect has been achieved.
- 1
Study on application of composite gelling agent in filling paste of Yunfeng Bauxite in Guizhou ProvinceAbstract:
In order to promote the resource utilization of industrial waste slag and reduce the carbon emission of backfill mining, cement-slash-red mud composite gelling agent was used to modify the filling slurry of Yunfeng Bauxite in Guizhou Province. Compressive strength, folding strength, shrinkage rate, permeability, freeze-melt resistance durability tests and microstructure observation were carried out, and the rule and mechanism of influence of red mud and slag content on backfill performance were analyzed. Combined with the field observation, the application effect of filling mining is evaluated. The results show that the compression strength, flexural strength, dry shrinkage, permeability resistance and freeze-thaw durability of the specimens modified by red mud and slag powder are significantly improved compared with the single cement paste specimens. When the mass ratio of cement, slag and red mud in the compound cement is 2:1:1, the properties of the filling paste reach the best. The use of composite gelling agent can promote the hydration reaction and micro-aggregate reaction of the gelling material, and then improve the physical and mechanical properties of the filling paste. The application of the art-flow filling platform in Yunfeng Bauxite mine in Guizhou Province shows that the use of cement-slag-red mud compound gelling agent can not only accelerate the resource utilization of industrial solid waste, but also bring significant economic benefits.
- 1
Study on the Mechanical Properties and Failure Patterns of Composite Rocks with Coplanar Double FissuresAbstract:
In order to investigate the impact of fissure configuration attributes on the mechanical behavior, failure patterns, and crack propagation characteristics of layered composite rocks, a study was carried out on pre-fabricated coplanar double-fissured composite rocks. This investigation encompassed indoor uniaxial compression tests and utilized a digital image acquisition module to analyze the mechanical properties and failure characteristics of rock samples across varying fissure lengths and angles. The outcomes disclosed the subsequent findings: (1) An escalation in fissure angle led to heightened peak stress and elastic modulus in the rock samples, whereas such parameters decreased with increasing fissure length. The degradation coefficient k displayed a decrement with increasing fissure angle and an increment with increasing fissure length. (2) The failure pattern was influenced by both the fissure angle and the two types of rock materials, with the degree of fragmentation primarily governed by fissure length. (3) The bridging mode of rocks was subject to fissure angle and structural planes. Among the four bridging modes, an elevated fissure angle correlated with an augmented bridging tendency. A fissure angle of 90° precluded further bridging due to structural plane inhibition. (4) Crack propagation was contingent on fissure length. When the fissure length was below 12mm, cracks predominantly emerged in the right half of the rock sample, while post-elastic stage cracks were principally observable in the left half. Exceeding a fissure length of 12mm resulted in a uniform distribution of cracks on the rock sample surface. These research findings carry substantial implications for practical engineering construction and design.
- 1
Study on Occupational Hazard Assessment and Classification Management of Dust in Coal Preparation Plant Based on Cooperative GameAbstract:
Dust in open-pit coal preparation plant has gradually become one of the core hazard factors that restrict the efficient, safe and environmental protection development of coal preparation plant. In order to evaluate the dust workplace of coal preparation plant scientifically and reasonably, considering the current situation of dust hazard in coal preparation plant and the fuzziness of evaluation method, the grey analytic hierarchy process and cooperative game weight technology are introduced to construct the comprehensive evaluation model of dust occupational hazard in coal preparation plant. Taking a coal preparation plant in Zhundong, Xinjiang as an engineering example, firstly, the typical dust source and dust production mechanism of the coal preparation plant are analyzed, and the occupational hazard assessment index system of the coal preparation plant is constructed from four aspects : the occupational prevention management of the coal preparation plant, the miners" status of the coal preparation plant, the environmental status of the coal preparation plant and the occupational prevention measures of the coal preparation plant. Secondly, based on the cooperative game combination, the comprehensive weight coefficient of each index is determined by using the analytic hierarchy process and the entropy weight method. Finally, the grey fuzzy technology is used to evaluate the dust hazard of the coal preparation plant. The research shows that the cooperative game weighting technology can effectively eliminate the subjective randomness and objective single error. The evaluation results of dust occupational hazards are consistent with the actual occupational prevention evaluation results.
- 1
Deformation failure characteristics and evolution mechanism of open-pit slopes caused by open-pit to underground miningAbstract:
Mining induced disasters such as landslides, collapses, and surface subsidence have always been a hot and difficult research topic in the field of disaster prevention and reduction engineering. In order to reveal the evolution mechanism of open-pit landslides and surface subsidence disasters caused by underground mining, remote sensing images, on-site investigations, and numerical simulation studies were used to study the deformation and failure characteristics of open-pit slopes and surface subsidence. The research results indicate that the formation of landslides in open-pit mining areas mainly undergoes the following processes: stability - slope collapse - large-scale collapse - surface subsidence cave - surface subsidence landslide - northern slope collapse. The northern slope angle is too steep, and there is a possibility of further collapse and landslide under the coupling influence of faults and underground voids. The formation mechanism of collapse pits is mainly divided into four stages: ① disturbance and collapse of overlying rock layers on the ore body; ② Open pit collapse; ③ Collapsed holes appear on the surface of the mountain; ④ The surface of the landslide and mountain collapse in the open-pit mining area. The deformation and failure characteristics of open-pit slope revealed by numerical simulation are consistent with the actual situation of the mine site, verifying the reliability of the numerical simulation results. In the process of deformation and displacement development of open-pit slope and mountain surface, there are three abrupt points, and the development of deformation and displacement is divided into four stages, which is consistent with the results of remote sensing images and on-site investigation and analysis. The research results provide reference for disaster prevention and control in the transition from open-pit to underground mining.
- 1
InSAR and numerical simulation for slope stability analysis and deformation prediction in Open Pit Mine DumpAbstract:
To address the problem that landslide risk still exists after the treatment of open-pit mine dumps. The Dagushan open pit mine dump was taken as an example. Firstly, the surface settlement time series monitoring was carried out by using the Short Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique. The main settlement areas and stability influencing factors of the slope of the discharge site could be analyzed. Then, relationships between internal slope displacements and safety factor response to rainfall were obtained with the help of COMSOL simulation. The synergistic analysis of the discharge field's spatial and temporal deformation characteristics is realized. Finally, the Particle Swarm Optimization (PSO) optimized Long Short-Term Memory (LSTM) prediction model integrating multi-category loss functions was constructed. Sedimentation time series prediction can be carried out. The results show that the discharge field is now basically stable, but there are three typical areas of subsidence in the north-central region. The maximum cumulative settlement amounted to 295.8 mm, and the maximum annual average settlement rate was about 134.2 mm/a. The effective rainfall is the influence factor of slope deformation, and maximum of the decrease rate in the safety factor is about 0.025% with the continuation of the previous rainfall process. The comprehensive evaluation index (Ltotal) of the PSO-LSTM model integrated with the multi-class loss function is less than 2.50, which can reflect the settlement fluctuation trend of the drainage field. Results can provide the theoretical basis and technical support for preventing and controlling landslide disasters in the dump.
- 1
Speed Planning and Obstacle Avoidance Method for Unmanned Mining Vehicle in Dynamic EnvironmentAbstract:
In addressing the autonomous obstacle avoidance problem for unmanned mining vehicles, a method based on speed planning and obstacle avoidance in dynamic obstacle environments is proposed. Firstly, the range swept by dynamic obstacles in the near future is mapped onto an s-t (distance-time) graph in a two-dimensional grid map. Then, an algorithm for determining a safe speed range based on the s-t graph is studied to ensure the safety of unmanned mining vehicle operations, and to achieve smooth speed variations, a quadratic programming (QP) speed optimization model based on optimal control principles is formulated. Finally, a hybrid A* algorithm is designed, utilizing the search results from the s-t graph as its initial solution to assist in solving the optimization problem. Simulation and on-road tests demonstrate that the proposed method achieves a success rate of over 98% and exhibits favorable real-time performance.
- 1
Research and Practice on Improving the Quality of Phase I Iron Concentrate of Xinbaima CompanyAbstract:
In order to increase the TFe grade of the first phase vanadium titanium iron concentrate of Xinbaima Company from 53.5% to over 55%,through particle size analysis of major mineral processes, grinding and selection tests, on-site process flow investigation, and analysis of final iron concentrate particle size and monomer dissociation degree,the performance defects of the first stage cyclone equipment, insufficient processing capacity of the second stage high-frequency fine screen, and mismatch between the processing capacity of the second stage mill and the classification equipment were found to be key factors restricting the TFe grade improvement of the first stage vanadium titanium iron concentrate.By using the FX840 flat bottom cyclone instead of the FX610 conical cyclone to optimize the primary grinding classification system, the circulating load of the primary grinding mill was increased by 5.74 percentage points, the unit volume productivity of -0.074mm was increased from 0.37t/(m3h) to 0.51t/(m3h), and the overflow content of -0.074mm in the cyclone was increased by 3.76 percentage points. The coarsening of the primary cyclone was significantly improved;The combined classification method of "cyclone+high-frequency screen" was adopted to transform the process flow of the two-stage grinding and classification system. The circulating load of the two-stage mill was increased to 439%, and the unit volume productivity of -0.074mm was increased from 0.74 t/(m3h) to 0.91 t/(m3h). The quality efficiency of high-frequency fine screen classification was increased by 4.73 times compared to before optimization, and the content of -0.074mm under the screen was increased by 16.37 percentage points. The -0.074mm content of the first phase iron concentrate was successfully increased from about 60% to over 70%, The goal of increasing the TFe grade of the first phase vanadium titanium iron concentrate from 53.5% to over 55% has been achieved while ensuring that the system"s raw ore processing capacity does not decrease.
- 1
Study on the effect of retarded acid on the initial velocity of gas emission in anthraciteAbstract:
Retarded acid is of great significance to reduce the reaction rate of coal and improve the recovery rate of coalbed methane. Taking anthracite coal in Guizhou as the research object, static dissolution, initial velocity of gas dispersion, carbon dioxide adsorption and infrared spectroscopy experiments were carried out, and the influence mechanism of pore structure and number of oxygen-containing functional groups on the initial velocity of gas dispersion in coal was analyzed from the physical and chemical perspectives. The results show that: 1) the acidification retardation effect is the best when the acetic acid concentration is 5%; 2) Compared with the raw coal samples, the initial velocity of gas dispersion of the hydrofluoric acidified coal sample increased. On the one hand, hydrofluoric acid improved the pore connectivity of experimental coal samples, increased the number of transition pores and macropores, and reduced the specific surface area of coal samples. On the other hand, the number of oxygen-containing functional groups in experimental coal samples increased after hydrofluoric acid treatment, and the surface structure tended to be simpler; 3) Corresponding to the raw coal sample, the initial velocity of gas dispersion of the retarded acid coal samples decreases. Retarded acid can not only increase the number of micropores and specific surface area of the coal samples, but also reduce the number of oxygen-containing functional groups of the coal sample, making the surface structure more complex.
- 1
Study on Process Mineralogical Characteristics and Optimization of Magnetic Separation Process of an Iron Ore Mine in HainanAbstract:
IIt is the common goal of China's mining enterprises to improve the level of ore development and utilization and to guarantee the supply capacity of mineral resources. Aiming at the problem of declining product quality in mineral processing caused by the change of mineral source in an iron ore mine in Hainan, the process mineralogy study of the raw ore was conducted through the field sampling, obtaining the mineral composition and mass fraction, the particle size distribution of the main minerals and the average partition of iron in different minerals were analyzed, and researching the degree of contiguity of the iron minerals and the embedded characteristics. Crushing classification and magnetic separation dry throwing test was carried out to determine the best magnetic separation conditions, optimize the magnetic separation process, and achieve the best beneficiation technical indexes. It is found that: the main composition of the ore is quartz as well as iron-containing minerals, of which, magnetite accounts for 8.4% of the total mineral content, and the internal iron content is as high as 59.86%. Magnetite is less contiguous with other iron minerals, but is closely embedded with quartz, which is unfavorable to beneficiation, and it should be focused on strengthening the intensity of grinding. Crushing and grading and magnetic separation dry throwing test shows that: after crushing and grading the raw ore, we get the products with two grain sizes of 10 mm~20 mm and less than 5 mm, according to the grain size to determine the optimal magnetic separation conditions, the optimal magnetic separation field strength of 10-20 mm grain size should be set at 1500 GS, and the optimal field strength of raw ore less than 5 mm grain size should be set at 1000 GS. the grade of the concentrate product after the optimization of the process is more than 30%, and the yield is 17.37%, and the iron recovery is 38.35%. After the optimization of the process, the grade of the concentrate product reaches more than 30%, the yield reaches 17.37%, and the iron recovery rate is 38.35%, which meets the requirements of the beneficiation indexes of the mine. The results of the study provide technical basis for the efficient utilization of iron ore resources.
- 1
Research on Optimization of Coal Pillar Setting Width in Shanyang Coal Mine SectionAbstract:
The main function of coal pillar in section is to maintain the stability of roadway and isolate toxic and harmful gases in goaf. Its size and stability not only affect the recovery rate of coal resources, but also affect the abutment pressure distribution of overlying rock on working surface and the stability of roadway surrounding rock. In order to solve the problem of insufficient width of pillar in Shanyang Coal mine section, the research methods of field investigation, theoretical analysis, experimental simulation, numerical simulation and field monitoring are adopted. The distribution of vertical stress, vertical displacement and plastic zone under coal pillars with different widths of 13, 15, 17 and 20m at 1531 working face is studied. Through theoretical calculation, the reasonable remaining width of coal pillar is more than 14.21m. Building a physical similarity model to study the width and stability of coal pillar in 1531 working face section. The experimental results show that the coal pillar is safe and stable when the width of coal pillar is reduced from 20m to 15m in 1531 working face section. When the coal pillar is reduced to 15m, cracks appear on both sides of the coal pillar. When the width of the coal pillar is reduced to 14m, cracks will occur in the overlying rock above the coal pillar, and there is a possibility of instability of the coal pillar. Therefore, the width of coal pillar is 15m. Through the numerical simulation analysis of plastic zone, vertical stress and displacement of coal pillar, the width of coal pillar is optimized to 15m.Meet the safety production requirements.
- 1
Optimization of the proportioning and hardening mechanism study of slag-based backfill materials regulated by finely ground coal fly ashAbstract:
In order to achieve the efficient utilization of fly ash and blast furnace slag and develop low-cost, high-performance cemented backfill materials for mining, a series of orthogonal ratio optimization experiments were conducted. These experiments explored the effects of fly ash content, Ca(OH)2, Na2SO4, and slurry concentration on the compressive strength, workability, and setting time of the slag-based cemented backfill materials. Optimal parameter ratios were obtained, and the influence of finely ground fly ash on the regulation and hardening mechanism of the slag-based materials was studied using thermogravimetric analysis and scanning electron microscopy. The results showed that the compressive strength of the backfill materials at 7 days and 28 days in the orthogonal experiments exceeded 2.6 MPa and 6.8 MPa, respectively. The alkaline activation of Ca(OH)2 played a crucial role in enhancing the compressive strength at 3 days, while the fly ash content had a significant effect on the overall compressive strength of the backfill materials. The optimal parameter ratio (Y sample) was determined as follows: fly ash content of 30%, Ca(OH)2 content of 15%, Na2SO4 content of 5%, and slurry concentration of 80%. When the mass concentration was greater than or equal to 70% and the fly ash content increased, the spread diameter and slump value of the slurry decreased to 21.2 cm to 33.6 cm and 20.3 cm to 22.9 cm, respectively, while the viscosity and yield stress increased to 4.55 Pa·s to 5.32 Pa·s and 571 MPa to 852 MPa, respectively. The analysis of the hardening mechanism indicated that the addition of finely ground fly ash increased the endothermic peak of the hydration products such as C-S-H and ettringite around 110°C in the slag-based cemented backfill materials. The Y sample exhibited a weight loss of 4.80% at 3 days and 4.96% at 28 days, which indicated continuous reactions within the backfill materials, resulting in the formation of more C-S-H and ettringite. The interconnection and growth of these products led to a denser structure and reduced porosity in the backfill body, contributing to higher compressive strength.
- 1
Simulation of Rock Rheological Properties in JM Mine Based on Parameter Correction ModelAbstract:
The rheological properties of rock in block caving mining have a significant impact on the law of rock collapse. In order to clarify the rheological properties of JM mine rock, this article is based on the rheological test results of on-site rock samples, selects appropriate constitutive models through analysis and comparison, and simulates the influence of different parameters on the rheological curve of rock. The comprehensive analysis results indicate that among the Maxwell, generalized Kelvin, and Burgers Mohr constitutive models, the Burgers Mohr constitutive model has the best fitting effect on the rheological test data of JM mine rock, with a fitting correlation coefficient of 0.986; In the Burgers Mohr constitutive model, the Kelvin viscosity coefficient mainly affects the initial creep rate of the rock, the Maxwell shear modulus mainly affects the instantaneous deformation of the rock rheology, and the Maxwell viscosity coefficient mainly affects the initial amount of the isokinetic creep stage of the rock and the slope of the isokinetic creep stage curve. Without considering the impact of slope cutting engineering and the caving volume during the infrastructure period, the average annual collapse volume of the overlying ore rock was simulated to be 17.6 Mt, which is close to the design annual production capacity of 18Mt. This verifies the correctness of the parameters of the modified Burgers Mohr rheological model and provides useful reference for the caving law of rock in mines under similar geological conditions.
- 1
Research on Surrounding Rock Control Technology of Weakly Cemented Roadway under Tectonic StressYang Xia, 刘洪林, 杨焕河, 亓建, 于海军, 张明村
Abstract:
The excavation and maintenance of weakly cemented coal roadways in Xinjiang are generally difficult and poor safety, and it is of great significance to mine construction and production safety to grasp the characteristics of mine stress distribution. In this paper, the size and direction of the three-dimensional in-situ stress distribution in Weizigou coal mine are measured by the hollow envelope stress relief method, a numerical model is established based on the in-situ stress measurement results, the actual deformation and failure of the roadway is analyzed, and the corresponding support scheme is proposed. The results show that: (1) The stress field type of Weizigou mine is σHv type, and the maximum horizontal principal stress has obvious effects on the deformation and failure of the roadway and the appearance of ore pressure. (2) The degree of deformation of the surrounding rock of the roadway is affected by structural stress, and the overall performance is: top plate > right gang> bottom plate > left gang. (3) The support technology of "asymmetric anchor net cable spray + argillaceous floor grouting anchor" was proposed, which played a good control role in the deformation of the surrounding rock of the weakly cemented roadway under the action of structural stress, and achieved a good control effect of the surrounding rock of the roadway.
- 1
Evaluation of Landslide Susceptibility in Ionic Rare Earth Mining Area in Southern Jiangxi Province: A Case Study of Dinnan CountyAbstract:
Southern Jiangxi Province is an area of intensive distribution of ionic-adsorption rare earth deposits in China. While rare earth mining has made important contributions to local socio-economic development, it has also caused a series of ecological and environmental problems, such as slope stability weakening, which have attracted increasing attention. For this research, Dingnan County of Jiangxi Province, an ionic rare earth high-intensity mining area, was selected as the study area. Based on 538 historical landslide disaster points data, nine influencing factors were selected to construct the landslide susceptibility evaluation index system. The weighted information value model was applied to partition and evaluate landslide susceptibility. The model's predictive capacity was tested and compared through the ROC curve. The results show that slope, lithology, distance to roads and distance to rivers are the main inducing factors for landslides. Both models exhibit high prediction accuracy, with the very high and high susceptibility areas showing good agreement with the actual distribution of historical landslide disaster points. The information value model's very high and high susceptible areas account for 33.80% of the total area, including 86.24% landslide disaster points, with a disaster point density of 2.55 points/km2. Similarly, the weighted information value model's very high and high susceptible areas account for 25.50% of the total area, including 81.97% landslide disaster points, with a disaster point density of 3.21 points/km2. The weighted information value model (AUC = 0.869) yielded higher predictive accuracy than the information value model (AUC = 0.827) and is deemed more suitable for landslide susceptibility evaluation in ionic rare earth mining area.
- 1
Current Status and trend of Spodumene Flotation ProcessAbstract:
This article provides a systematic review and assessment of the research progress in lithium spodumene flotation technology. Firstly, the crystal structure of spodumene and the factors affecting its floatability were summarized. It then reviews the advantages, disadvantages, and practical applications of desliming and non-desliming flotation processes for lithium spodumene. Lastly, it focuses on the recent advancements and application status of flotation reagents for lithium spodumene, including collectors and modifiers. The article identifies the current issues and research status in lithium spodumene flotation technology and emphasizes that, in the current trend, the primary development direction for lithium spodumene flotation should be centered around screening and developing efficient flotation reagents. This provides important references and insights for the practical application of lithium spodumene flotation technology.
- 1
Dynamic Crushing and Energy Consumption Mechanism of Magnetite Based on Mineral CharacterizationAbstract:
In order to study the crushing characteristics and energy consumption law of magnetite stone under dynamic loading, a sedimentary metamorphic magnetite stone was taken as the research object, and impact crushing experiments were carried out on the magnetite stone by using a separated Hopkinson press bar to analyze the kinetic characteristics, crushing energy consumption and crushing morphology of the magnetite stone in combination with the theory of mineral characteristics. The outcomes show that the stress-strain curve of magnetite stone under impact loading presents three stages: the elastic stage, the crack development stage, and the unloading stage. With the increase of incident energy, the crushing energy consumption and energy density increase continuously, and the crushing average diameter decreases with the increase of energy density. Under low incident energy, the energy is stored in the form of elastic energy inside the quartz particles, and when the stress wave action is over, the energy is released for the expansion of the original cracks, destroying the internal structure of the specimen. Under high incident energy, the rate of storing elastic energy in quartz particles is accelerated and reaches the storage limit faster, the internal energy is released rapidly, the original fissures are expanded rapidly and a large number of along-crystal and through-crystal fissures are generated, and the internal structure of the specimen is seriously damaged. The magnetite is mainly composed of quartz, and the structure and contact relationship of the ore is simple, with the crystalline structure, accountable structure, strip structure and block structure, and the mineral particles show line contact with each other, and the crushing is mainly based on along-crystal rupture and through-crystal rupture, with the stepped and serpentine rupture morphology.
- 1
Experimental Study on Beneficiation of Huangshaping High Carbon Copper lead Mixed ConcentrateAbstract:
The raw ore of Huangshaping lead-zinc mine contains 0.10% to 0.2% of copper. The copper lead mixed concentrate produced by Huangshaping Lead Zinc Concentrator contains 1.25% Cu and 59.64% Pb。The mixed concentrate has high organic carbon content, fine particle size, easy floatation and difficult suppression, and it also absorbs a large number of reagents. The traditional copper lead separation process and flotation reagents cannot be used for effective separation. According to the characteristics of the ore, the technological process of "stirring and desliming - sedimentation and desliming (carbon) - lead suppression and floating copper" is adopted, and the efficient lead inhibitor CK-DQ is applied. Finally, a copper concentrate with a copper grade of 22.31%, a lead content of 4.52%, a recovery of 68.22%, a lead concentrate with a lead grade of 61.82%, a copper content of 0.23%, and a recovery of 99.63% is obtained, realizing the efficient separation of low copper and high carbon copper lead mixed concentrate without chromium.
- 1
ANALYSIS ON IMPACTING POSITION OF ORE-ROCK ON INCLINED OREPASS FLOOR AND ITS INFLUENCE FACTORSAbstract:
The collision between the moving ore-rock in the inclined orepass and the orepass wall will lead to the impact damage of the orepass wall and affect its service life. In order to reveal the impact damage law of the ore-rock movement in the inclined orepass on the chute floor, based on the kinematics principle, the influencing factors and characteristics of the movement law of the ore-rock block in the inclined orepass are studied, and the trajectory equation of the ore-rock block in the inclined orepass is established. The collision condition between the ore-rock block and the inclined orepass floor is determined, and the calculation formula of the position of the ore-rock block colliding with the inclined orepass floor for the first time is obtained. The research shows that: (1) The initial movement of ore-rock and its direction angle, the distance between the roof and floor of the inclined orepass and its dip angle are the main factors affecting the collision between the ore-rock block and the floor of the inclined orepass. (2) The smaller the initial velocity of the ore-rock, the larger the initial velocity direction angle, the distance between the top and bottom of the inclined orepass and its dip angle, the larger the distance from the collision position to the entry of the ore-rock into the inclined orepass, and vice versa. (3) When the initial velocity of the ore-rock and its direction angle are constant, the larger the distance between the top and bottom of the inclined orepass and its dip angle, the larger the distance between the collision point and the ore-rock block entering the inclined orepass, and the distance between the top and bottom of the inclined orepass has a greater influence on the collision position; (4) Selecting reasonable structural parameters of the branch orepass and the main inclined orepass, reducing the initial velocity of the rock mass entering the inclined orepass, and appropriately increasing the distance between the roof and floor of the main inclined orepass and its inclination angle can effectively reduce the probability of collision between the rock mass and the floor of the main inclined orepass, thereby reducing the degree of impact damage to the floor.
- 1
Study on Flow Characteristics and Strength of Backfill with Tail Salt Based on Different Stirring ParametersAbstract:
In order to improve the quality of potash mine tailing paste filling and realize low-cost and high-quality tailing filling, the effect of mechanical mixing on tailing slurry was investigated, and the mixing effect of filling slurry was studied under different mixing time and rotation speed. The expansion degree and collapse degree of the tailing salt slurry under different mixing conditions, as well as the 3d, 7d and 28d strength of the specimen blocks were tested. The results show that: the increase of mechanical stirring speed or time can improve the homogeneity of the tailing salt filling slurry, and the large particles in the slurry are obviously reduced; the increase of mechanical stirring intensity can improve the fluidity of the filling slurry, when the stirring speed is 1120 r/min and the stirring time is 150 s, the stirring rotor has the highest stirring efficiency of the filling slurry, and the slurry has a better liquidity; the increase of both stirring time and stirring speed can improve the fluidity of material particles; the increase of stirring time and stirring speed can improve the fluidity of material particles. The increase of stirring time and speed can improve the number of collision of material particles, strengthen the reaction effect of tailing salt and calcium oxide, and improve the strength of tailing salt filling body within a certain range.
- 1
Research on Low-cost Gelling and Solidifying Materials for Solid Potash Tailings in LaosAbstract:
In order to solve the problems of difficult consolidation of potash tailings and old brine and high cost of consolidation, this paper researches and develops low-cost gelling and curing materials. Firstly, we investigated the cementation characteristics of traditional conventional cementing materials mixed with tailing salt, developed two new cementing materials according to the cementation characteristics of tailing salt, and investigated the cementation strength of the new cementing materials with tailing salt under different gray sand ratios and concentrations. The results show that: calcium oxide has poor cementation effect and low compressive strength after mixing with tailing salt when the gray sand ratio is large, while the strength of test block can reach 1.20 Mpa when the gray sand ratio is low; magnesium oxide can obviously improve the strength of the filling body when it is used as the cementing material of tailing salt, and the strength of the test block can reach up to 22.06 Mpa; fly ash and steel slag cannot achieve the solidification of tailing salt and old brine when they are used as the cementing materials of tailing salt; and the strength of test block can reach up to 22.06 Mpa when they are mixed with the tailing salt. When fly ash and steel slag are used as tailing salt cementing material, tailing salt and old brine can"t realize solidification, which is not suitable to be used as the main body of new cementing material. The #1 new cementitious material developed by the research and development, mixed with the tailing salt after consolidation of the strength of the test block is low, the highest strength only reaches 1.20 Mpa, can not meet the performance requirements of the filling slurry, but compared with the calcium oxide, it can reduce the roughness of the surface of the filling body, the development of the #2 new cementitious material in the ash-sand ratio of 1:8 and the slurry concentration of 72%, the strength of the test block of the 28d can reach 3.17 Mpa; Compared with magnesium oxide, the cost of filling cementitious material is reduced by more than 50% under the condition of comparable strength.
- 1
Experimental Study on Brazilian Fracture of Organic-rich Shale after Real-time High Temperature and High Temperature CoolingAbstract:
During in-situ thermal fracturing (TFF) of organic-rich shale, the tensile strength under the action of thermodynamic coupling directly relates to the strength and stability of the shale seam, which has a crucial impact on the mining of shale. To study the relationship between the mechanical characteristics of shale fracture and temperature change under high-temperature steam heating and after cooling with steam heating, the Brazilian splitting test was carried out on 500 °C organic-rich shale by using a self-developed real-time high-temperature steam testing system and rock pressure machine. With the increase in temperature, the experimental results show that the tensile strength increases first and then decreases after high-temperature steam heating and cooling, reaching its maximum value at 300°C; under real-time steam heating, the tensile strength decreases first and then increases, reaching its lowest point at 400°C. The fractured cracks in shale samples are complex cracks, with a main crack being a transversing crack and secondary cracks being bedding cracks. Furthermore, with the increase in temperature, the number of secondary cracks increases. The research results have important engineering significance for determining fracturing parameters when reconstructing fluid transport channels.
- 1
Research and application of tunneling technology along the air in the coal pillar of thick coal seamAbstract:
In order to ensure the stability of the coal pillar and the roadway, and avoid the waste of coal resources, the working face of thick coal seam needs to determine the reasonable width of the section coal pillar, Xiaoyu Coal Mine proposes to carry out the research on the technology of small coal pillar excavation along the empty roadway in the 2202 roadway, and through the combination of theoretical calculations, numerical simulation and on-site tests, it has determined that the reasonable width of the section coal pillar retained in the working face of the thick coal seam is 7.8m. The deformation and stress of the roadway perimeter rock in the two phases of the digging and mining back period were monitored and analysed, and the results of the on-site monitoring data showed that: Along the air excavation roadway in the process of digging, the maximum value of the roadway two gang shift is 73mm, the maximum value of the top and bottom plate shift is 62mm; In the process of mining back, the maximum value of the two gangs of the roadway moving close to each other is 805mm, and the maximum value of the top and bottom plate moving close to each other is 604mm, so that the deformation of the peripheral rock of the roadway is effectively controlled, and the roadway is in the area of stress reduction, and the optimum width of the coal pillar of the section of the working face of the thick seam of Xiaoyu Mine is finally determined to be 7.8m. The conclusions of this study provide valuable experience in the adoption of along-the-air tunneling technology for working faces in similar mines.
- 1
Research on Surface Movement Law of Joint Mining in Multiple Mining Areas of Metal Mines with "Open-Caving-Filling"Abstract:
The surface movement and deformation caused by multi mining areas and multi method joint mining of metal mines are complex. In order to reveal the law of rock mass movement and deformation during joint mining, a three-dimensional finite element fully elastic numerical simulation calculation was carried out using the "open-caving-filling" joint mining of Dahongshan Iron Mine as an example. The displacement monitoring data of the surface automatic total station instrument were analyzed. The research results showed that compared to the filling method mining of No. I copper mine, The main ore body caving method has the greatest impact on surface movement and the stability of open-pit slopes, with the movement range crossing the F2 fault and affecting the top boundary of the open-pit; The horizontal displacement of the top boundary of the open-pit during underground filling and caving mining is reversed, and the slope is prone to tension and cracking; The northern part of the underground main mining area is prone to cracking along the vein under the superimposed mining stress; The monitoring data shows that although the settlement displacement caused by underground caving mining has not affected the open-pit slope, the slope has good stability characteristics, and the surface cracking range has not significantly expanded, the movement range has further expanded. Based on the results of numerical calculation and monitoring data analysis, safety protection measures for joint mining have been proposed, including slope protection, design optimization, monitoring system upgrade, and backfilling treatment of collapsed pits and waste rocks. This is beneficial for the safe and stable transition of multi mining areas and multi method joint mining in Dahongshan Iron Mine.
- 1
Experimental study on coal-rock recognition method based on signal detection and algorithm analysisAbstract:
Aiming at the problem of low accuracy of coal rock recognition with different hardness, a coal rock recognition method is proposed by using coal rock cutting experiment combined with Kalman filter algorithm and random forest algorithm. By constructing the coal-rock cutting device and completing the similar simulation cutting experiment, the cutting device is used to cut one kind of coal seam and five kinds of coal-rock combinations with different hardness in the similar simulation experiment. The three-phase current characteristic signals of the three-phase motor under six cutting conditions and the infrared thermal imaging temperature characteristic signals of the contact surface between the simulated cutting drum and the coal-rock mass are collected. With the increase of the hardness of coal rock mass, the peak value of three-phase current and infrared thermal imaging temperature will increase. When cutting the same kind of coal and rock mass, the three-phase current and infrared thermal imaging temperature will increase with the increase of the contact area between the simulated cutting drum and the rock layer. The two types of signal data are aggregated into original samples, and the original samples are processed by Kalman filter algorithm. Then, the original samples and the samples processed by Kalman filter algorithm are classified and compared by random forest algorithm. The results show that this method can greatly improve the number of correctly predicted samples and improve the recognition accuracy of coal rock. It provides a reference method for intelligent and accurate coal cutting of shearer.
- 1
Exploration of vehicle-mounted spray dust reduction system based on the law of transport dust escapeAbstract:
In order to improve the problem of high-concentration dust generated in the transportation of open-pit iron mine, theoretical analysis and numerical simulation are combined, and the law of dust emission at different speeds is simulated by Fluent software, and a vehicle-mounted spray dust suppression system is designed to explore its atomization effect. The results show that when the vehicle speed is 10km/h, the dust will move to the rear of the truck with low airflow intensity and low running speed. The friction between the tire and the ground is the maximum concentration of point dust in the transportation link, and the concentration is 4.6kg/m3 to 30 km/h. The dust will escape from the inside to the outside in a large range, reaching about 5m, increasing to 9.8kg/m3, and the maximum concentration of dust in the breathing zone is 2.24 kg. Based on the escape law of transportation dust, the atomization effect of different spray parameters is simulated and analyzed. It is confirmed that the medium pressure nozzle has the best atomization effect at the pressure of 3Mpa, the atomization angle of 60 and the diameter of 1.0mm, which can ensure the capture of all dust and respiratory dust at the same time.
- 1
The Current Situation Analysis and Study on the Construction Strategy of Intelligent Professional Talent Team in Coal MinesAbstract:
The "dual carbon" strategy is a catalyst to promote the reform of China's energy industry. However, it is difficult for the lack of intelligent talent teams to meet the needs of the rapid development of intelligent coal mines. To address this issue, the Pearson correlation algorithm was used to test the reliability and validity of the questionnaire data of college graduates who worked in coal mining enterprises from 2021 to 2022 for the past 5 years as the research sample. On this basis, the weak link of talent cultivation is analyzed based on the Chi-squared test algorithm. Then, further analyzing the contradiction between discipline teaching and enterprise demand based on the Hierarchical clustering algorithm, and integrating the principal component analysis algorithm and DBSCAN density clustering algorithm to explore the impact of professional teachers on the construction of intelligent professional talents in coal mines. Finally, the construction strategy of intelligent professional talent team in coal mines under the constraint of "dual carbon" goal is studied. The effective implementation of this strategy can provide novel ideas for accelerating the training of intelligent talents in coal mines, thereby helping to achieve the "dual carbon" goal.
- 1
Experimental Study on Prediction of Blasting Vibration Velocity Based on An TPE-BP Neural NetworkCUI Hongyan, 张子禄, 胡静
Abstract:
The peak velocity of blasting vibration is one of the reference factors for reasonable blasting design. However, in the prediction of blasting vibration, the determination of hyperparameters in BP neural networks relies on empirical formulas and is subjective. To overcome this limitation and improve the accuracy of vibration prediction, the hyperparameter optimization algorithm TPE is used to optimize the blasting parameters of the BP neural network. Using the five influencing parameters of maximum segment charge, blast hole depth, horizontal distance, vertical distance, and explosive unit consumption as inputs, the model was applied as an example. The BP neural network with 31 hidden layers was optimized to achieve the highest prediction accuracy, with an average prediction error of 2.35% and a maximum error of 6.29%. Comparing the model with traditional empirical formulas and a single BP neural network model, TPE-BP prediction is closer to the true value, and the average error is also reduced by 4.24%. The results indicate that the parameters optimized by TPE-BP network can better fit vibration data, providing reference basis for researchers to use BP neural network for blasting parameter design, thereby further effectively controlling blasting vibration.
- 1
Beneficiation Wastewater of a Tungsten Polymetallic MineExperimental Study on Treatment and Reuse TechnologyAbstract:
In order to solve the problem that the residual drug dose and water quality of a tungsten polymetallic mine in Hunan Province can not be reused, developed a new technology of high efficiency flocculation and clarification-micro-electrolytic oxidation flocculation treatment and reuse of reagent (CR-2). After the treatment of mineral processing wastewater by the new technology, it can not only discharge up to the standard but also be reused for molybdenum and tungsten flotation, realizing the effective purification and efficient reuse of wastewater.
- 1
Research on deformation characteristics and control optimization of surrounding rock in inclined coal seam mining roadwayAbstract:
In response to the problem of asymmetric large deformation in the inclined coal seam mining roadway, taking the transportation roadway of the 1183 mining face of Changxing Coal Mine as an example, the surrounding rock fragmentation at a distance of 20m ahead of the working face of the roadway was observed to determine the range of its loosening zone. And a numerical model was established to analyze the impact range of mining disturbance on the mining roadway. The stress evolution law around the roadway and the deformation characteristics of the surrounding rock of the roadway were studied. The results showed that within a distance of 30 meters from the mining face, the deformation of the mining roadway was relatively large, making it a severely affected area of mining disturbance. As the distance from the mining face increases, the impact of mining disturbance on the mining roadway decreases. In order to better control the deformation of the roadway, a combined support system of anchor rods, anchor cables, and nets is proposed, supplemented by grouting reinforcement and a joint control method of "top pulling and bottom controlling" for surrounding rock. Grouting and strengthening the surrounding rock can improve its integrity. Injecting anchor rods into the roof or bottom plate at a certain angle on the roadway side can improve the integrity of the surrounding rock in the roadway. Field practice has shown that, This combined support method can effectively solve the problem of large deformation of inclined coal seam mining tunnels due to strong mining disturbance.
- 1
Study on Fault Slip Law and Instability Risk Sensitivity Induced by Mining in Metal MinesAbstract:
The faults are prone to shear slipping and sustaining damage by mining operations in metal mines, posing a severe threat to safe mining activities. This study employs numerical simulation using FLAC3D to investigate the factors that contribute to fault slip damage induced by metal mining. The findings reveal distinct spatial characteristics in shear displacement and shear stress along the fault surface. Moreover, the use of a fault slip hazard index allows for the quantitative assessment of the risk range associated with fault slipping. An increase in the number and intensity of blasting disturbances, coupled with a decrease in frequency, progressively escalates the risk of fault slip, thus amplifying the potential dangers. The mining factors that significantly influence the high-risk range of fault slip, in ascending order of importance, are the dip angle, disturbance frequency, disturbance intensity, internal friction angle, disturbance frequency, and ore body thickness. Notably, ore body thickness and blasting disturbance frequency emerge as the primary determinants of fault instability and activity levels during mining operations, providing theoretical and technical support for the effective control of faults in metal mining endeavors.
- 1
Resource Utilization Status and Key Technologies of Abandoned MinesAbstract:
How to dispose of abandoned mines is a key issue in the field of energy and environment in the world, which seriously affects the coordinated development of global resource development and environmental protection. Proper reuse of a large number of resources left after mine abandonment is one of the important ways to transform abandoned mines. This paper introduces the status quo of abandoned mines at home and abroad and the status and characteristics of resource utilization of abandoned mines, describes the potential hazards of abandoned mines, expounds the connotation and key scientific issues of comprehensive utilization of abandoned mines, and discusses key technologies such as geothermal energy development and utilization of abandoned mines, accurate utilization of groundwater resources, and construction of underground gas storage. The paper points out the technical difficulties in the investigation and evaluation of geothermal energy resources in abandoned mine, calculation of the stability and water storage capacity of the coal pillar dam of underground reservoir and the location of underground gas storage, and puts forward the idea of resource utilization of abandoned mine. The analysis shows that the comprehensive reuse of abandoned mine resources has broad application prospects in the transformation and sustainable development of abandoned mine, and can promote the transformation and development of resource-exhausted cities in China.
- 1
Research on Extension Cloud Model for Improving Emergency Management Capability of Rock Burst Based on PPRR TheoryAbstract:
A comprehensive evaluation model based on improved extension cloud has been established to further enhance the reliability of the evaluation of the emergency management capability for deep mine rock bursts, which is characterized by complexity, fuzziness, and uncertainty. Firstly, based on the PPRR (Prevention, Preparation, Response, Recovery) crisis management theory and combined with the characteristics of rock burst accidents, a multi-level evaluation index system for rock burst emergency management capability was constructed; Secondly, the comprehensive weights of indicators are determined using the method of order relationship analysis (G1 method), anti entropy weight method (A-EWM method), and combination weighting method (CW method); The theory of blind numbers has been introduced, and a blind number matrix has been established to scientifically process qualitative indicator data. This improves the traditional weighting mode of intuitive scoring by experts in topological cloud models. Based on the principle of topological cloud models, the comprehensive correlation degree of clouds at different levels is calculated, and the emergency management capability level is comprehensively analyzed and evaluated according to the maximum membership degree classification requirements. Finally, the established evaluation model was applied to analyze the emergency management capabilities of rock burst in three mines, and the results were compared with fuzzy mathematics and stochastic Petri net (SPN) evaluation models. The results show that the emergency capabilities of the three mines are Level IV, IV, and IV respectively, which are consistent with the conclusions of expert on-site research and the actual situation of the mine. The evaluation results of the three evaluation models are basically consistent, verifying the adaptability and effectiveness of this model in evaluating the emergency management capability of rock burst. The advantages of this model in evaluating the emergency management capability are analyzed and compared. This evaluation model can provide a practical, feasible, reasonable, and effective method for the quantitative evaluation of crisis management capabilities.
- 1
Dynamic response of jointed rock mass near blast hole under impact loadingAbstract:
In order to study the propagation mechanism of impact loading on the joint surface of rock mass in the process of borehole blasting, the stress distribution, vibration velocity and displacement distribution of the joint surface are numerically studied by two models with different joint forms in this paper. In model Ⅰ, the spatial distance between the blast hole and the joint surface is changed in the case of parallel joint surface with different joint thickness, while in model Ⅱ, the inclination angle of the joint surface is changed under fixed joint thickness and spatial distance. The results show that the dynamic response of the joint surface decreases significantly with the increase of the spatial distance between the blast hole and the joint surface when the thickness of the joint surface is constant. However, there is also a weakening effect on the dynamic response of the joint surface with the increase of the thickness of the joint surface when the spatial distance is fixed. In addition, when the inclination angle of joint surface is less than 45°, the peak values of stress and vibration combined velocity are gradually weakened with the increase of inclination angle, while the peak values of stress and vibration combined velocity are gradually enhanced when the inclination angle is more than 45°. The difference is that the inclination angle of 45° is taken as the limit, the stress peak decay rate decreases gradually when it is less than 45°, and increases gradually when it is greater than 45°. However, the peak attenuation rate of vibration combined velocity increases all the time, and the degree of increase becomes obviously stronger when the inclination angle is more than 45°.
- 1
Study on the Correlation Between Coal Pore Structure and Spontaneous Ignition Temperature Based on Correlation Coefficient MethodAbstract:
In order to explore the correlation between pore structure parameters in coal and coal spontaneous ignition temperature, liquid nitrogen adsorption experiments were used to test the pore structure and pore size distribution of four coal samples with different degrees of metamorphism. Thermogravimetric experiments were used to obtain the coal spontaneous ignition temperature and ignition ability. Finally, the Pearson correlation coefficient method was used to establish the relationship between the two. The results indicate that as the degree of metamorphism increases, the adsorption capacity, specific surface area, and pore volume of coal pores first decrease and then increase, while the proportion of mesopores gradually decreases and the proportion of macropores gradually increases. Meanwhile, as the degree of metamorphism increases, the quality curve and quality change curve of coal move towards the high-temperature zone, the ignition temperature gradually increases, and the spontaneous combustion ability weakens. The calculation results of Pearson correlation coefficient method show that the correlation coefficients between specific surface area, 2-10nm, 10-20nm, and>50nm pore size ratio and ignition temperature are -0.853, -0.895, -0.910, and 0.921, respectively. The lower the content of macropores in coal, the higher the content of mesopores, the larger the specific surface area, and the more convenient it is to contact oxygen, resulting in a lower ignition temperature and stronger coal spontaneous combustion ability. Finally, based on the results of the correlation coefficient method, a multiple linear regression model was established for the relationship between coal pore structure and ignition temperature.
- 1
Study on width optimization of coal pillar in hanging wall goaf fault footwall miningAbstract:
Under the influence of faults and mining, the width of coal pillars on the fault side of the footwall working face restricts the safe and stable production of the working face. In order to improve the recovery rate of the working face and ensure its safe and stable production, the footwall working face of the second panel of Huangling Coal Mine was taken as the engineering background. The theoretical analysis, numerical simulation and similar simulation were combined to study the internal relationship between the load above the coal pillar on the fault side of the footwall working face and the size of the coal pillar after the goaf of the hanging wall working face. The displacement, stress evolution and plastic zone distribution characteristics of the coal pillar width of 30 m, 26 m, 22 m, 20 m, 13 m and 6 m were revealed. The structural characteristics of the overlying rock when the coal pillar width was 30 m were analyzed, and the reasonable coal pillar width of the working face was comprehensively analyzed and optimized. The results show that under the influence of fault and mining, with the decrease of coal pillar width, the load above the coal pillar on the fault side of the footwall working face is divided into load reduction zone, load transition zone and load stability zone. When the width of the coal pillar is 30 m, the high rock layer on the fault side of the footwall working face is separated, and the stress concentration degree above the coal pillar is greater than that on the other side, with strong bearing capacity and high stability. When the width of the coal pillar is reduced to 22 m, the maximum subsidence and stress concentration of the roof near the fault side increase significantly, and the plastic failure of the coal pillar begins to occur, and the bearing capacity gradually weakens. When the width of the coal pillar is reduced to 13 m, the plastic zone on the fault side develops to the two ends of the working face and above the coal pillar, and the stability of the coal pillar is poor. When the coal pillar width is reduced to 6 m, the maximum subsidence and stress concentration of the roof near the fault side continue to increase, and the plastic zone continues to develop. Through similar simulation test, it is found that when the width of coal pillar is 30 m, the roof collapses and fills the goaf, and there is no obvious change above the coal pillar on the fault side of the footwall working face. Based on the above analysis, it is determined that the reasonable width of the fault side coal pillar in the footwall working face is 18 ~ 22 m, which can improve the recovery rate of the working face and ensure the safe and efficient production of the working face.
- 1
Study on the energy evolution mechanism of rock breakage by TBM cutters and the optimization of operational parameters under the condition of argillizationAbstract:
When the TBMs excavate in the mudstone strata, the rock debris is prone to adhere to the surface of the cutters and cutterhead. The "mud cake" occurs, which seriously reduces the tunneling efficiency of TBM. In order to reveal the effect of argillization on the rock-breaking efficiency of TBM cutters and prevent the argillization, the discrete element program PFC 3D was used to simulate the rotatory cutting process of TBM on mudstone, the total energy E, elastic strain energy Ee, friction energy Eμ, damping energy Eβ, kinetic energy Ek and bonding energy Ea were calculated. The rock-breaking mechanism of TBM cutters under the condition of argillization was studied from the perspective of energy evolution. Subsequently, the energy characteristics during the rock breaking process under different thrusts, tip angles and tip widths were analyzed. According to the principle of "lowest cumulative heat and cumulative bonding energy, and lowest mass of mud adhering to the cutter", the optimal operational parameters were obtained. The results show that the linear model of cohesive rolling resistance in PFC 3D can be employed to simulate the argillization process. Under the condition of argillization, the formation of slacking mudstone will significantly increases the mechanical work, consume a large amount of energy, and reduce the rock cutting efficiency of TBM. Increases of the thrust of the disc cutters can promote the formation of slacking mudstone, which will lead to the heating of the cutters and induce the adhesion of slacking mudstone on the surface of the cutters. The optimal tip angle is 40°, and the optimal tip width is 13 mm. The present study will provide theoretical references for the prevention of "mud cake" in related projects.
- 1
The Impact of Different Panel Layout Methods on Mining Subsidence under Repeat Mining ConditionsAbstract:
With the development of deep coal mining, mining subsidence caused by repeat mining has significantly impacted the ecological and geological environment of mining areas. In order to study the impact of different panel layout methods on mining subsidence under repeat mining conditions, a coal mine in Shanxi Province was chosen as the research object. By combining the engineering geological conditions of the study area and using MIDAS GTS/NX for numerical simulation analysis, the surface subsidence values and overburden stress-strain characteristics of various 3D geological models during mining were compared. The conversion of underground mining space to surface subsidence under different panel layout methods was analyzed, and the impact pattern on mining subsidence was summarized. The results show that the vertical parallel panel layout causes smaller surface subsidence compared to the vertical perpendicular layout. During the repeat mining process, on one hand, the underground mining space formed by the vertical parallel panel layout is smaller than that of the vertical perpendicular layout; on the other hand, the disturbance to the "stress arch" caused by the vertical parallel panel layout is smaller. Therefore, when the panels are vertically arranged in parallel, it can effectively reduce the conversion of underground mining space to surface subsidence and mitigate the impact of mining subsidence. Through the numerical simulation and analysis in this study, it is concluded that under permissible conditions, the vertical parallel panel layout can minimize the ground subsidence caused by repeat mining and provide technical support for the scientific prevention and control of mining areas.
- 1
Mechanical Properties and Parametric Damage Characteristics of Sandstone under the Action of Low Velocity Water FlowAbstract:
Uniaxial compression failure and crack propagation characteristics of prefabricated fractured rocks were studied at different loading rates, and uniaxial compression test and acoustic emission test were done by prefabricating rock-like materials with different fractured inclination angles. According to research results, in loading process, prefabricated fractured rocks mainly show tension cracks at first, then undergo a gradual transition to shear cracks which finally become shear failure. At the same fractured inclination angle, peak strength and elasticity modulus of test piece are positively correlated to loading rate; the inclination angle of cracks changes from 0° to 60° at the same loading rate, the characterized peak strength of test piece shows an overall trend of decrease first and then increase, and the peak strength is the lowest when α is 30°. The combination of acoustic emission count characteristics and stress-strain curve can intuitively and accurately reflect the failure process of prefabricated fractured rocks in loading process, and the changes of acoustic emission count can correspond to stress-strain curve one to one. Particularly in post-peak phase, acoustic emission count characteristics can intuitively reflect larger failure scale of test piece in post-peak phase, which means final failure of test piece occurs in post-peak phase.
- 1
Study on Mechanism of Surfactant Hydrolyzed Ions Synergizing with Special Group to Wet Coal DustAbstract:
To improve the efficiency of coal dust control, the wettability of ammonium lauryl ether sulfate (ALES), sodium lauryl ether sulfate (SLES), and sodium dodecyl sulfate (SDS) and their adsorption capacity on the surface of coal dust were tested by surface tension, Walker sedimentation, scanning electron microscopy, and infrared spectroscopy, and the electrostatic potential (EP), H-bonds, and density distribution were calculated by molecular dynamics simulation, and the effects of hydrolyzed ions and special groups on the wetting of coal dust were investigated. The results show that ALES has a stronger ability to wet and adsorb coal dust than SDS and SLES. This is mainly due to the fact that the hydrolyzed anions and cations of ALES can penetrate to 27 ? and 35 ? on the surface of low-rank coal, which has a stronger penetration ability; moreover, the hydrolyzed anions and cations of SDS had large EP values of -0.17759 a.u., 0.32626 a.u., respectively, which makes it difficult for water molecules around them to diffuse on the surface of the coal dust due to the constraints; NH4+ and EO groups increase the number of hydrogen-bonding associations, which enhances the adsorption capacity of ALES, and improves the wettability effect of it on the coal dust.
- 1
Study on the Properties of New Cement-Fly Ash Based Spraying Material of Gas Sealing in MineAbstract:
Spontaneous combustion of coal in goaf is one of the major disasters faced in coal mining. It not only wastes coal resources，causes significant economic losses，but also leads to accidents and casualties. To minimize the ingress of oxygen into the goaf，gas-sealing materials are frequently sprayed on the coal wall adjacent to the goaf，aiming to seal the cracks generated by mining activities. A new type of sprayed gas-sealing material was prepared by modifying cement and fly ash as matrix materials with hydroxypropyl methyl cellulose （HPMC） and tributyl phosphate （TBP）. The effects of different dosages of HPMC and TBP on the coating properties were derived from the water precipitation rate test，water retention rate test，mechanical strength test and contact angle test at the interface between cementitious materials and coal. The experimental results show that the best comprehensive performance of the material is achieved when the water-solid ratio is 0.5，the content of fly ash is 20%，the content of HPMC is 0.2% and the content of TBP is 0.08%. The water precipitation rate of the slurry is lower than 5%. The 7 d compressive strength and flexural strength of the material can reach 16.70 MPa and 5.02 MPa，respectively，which are increased by 6.58% and 2.87% compared with the pure cement-fly ash material. The initial contact angle between the modified slurry and the coal is reduced by 21.83°. Finally，the effect of admixtures on the hydration mechanism and microstructure of cement was derived from x-ray diffraction analysis，fourier infrared spectrum analysis and scanning electron microscope analysis.
- 1
Research on the technology of cutting the top and unloading pressure in front of the support in the working face with hard top plateAbstract:
In response to the issue of excessive support pressure caused by the difficult collapse of the hard roof in the upper part of working face 21606 at Qinglong Coal Mine, theoretical calculations, numerical simulations, and on-site measurements were employed to analyze the characteristics of overlying strata migration before and after cutting the roof, as well as the support pressure on the working face after roof cutting. Industrial field experiments have validated the depressurization effect of pre-cutting technology. The results indicate that the implementation of roof cutting technology can sever the interconnections between the hard roof plates. Based on the forced roof caving fracture mechanics model, the initial fracture step distance of the first basic roof after roof cutting is calculated to be 27.3 m, while the initial fracture step distance of the second basic roof is 50.3 m. Compared to the conditions without roof cutting, these distances are reduced by 4.7 m and 8.3 m, respectively. Numerical simulations analyzed the migration pattern of the overlying strata, revealing the optimal cutting height to be 15 m. After roof cutting, the average support pressure of the working face support is reduced from 36 MPa to 26.5 MPa (a decrease of 26.4%). The basic roof of the working face is completely fractured after mining 50 m. Based on the pressure regulation, the implementation interval spacing for roof cutting technology is determined to be 50 m. Pre-cutting depressurization technology shows promising results in reducing the collapse of coal wall fragments, increasing the collapse of the goaf side roof, and lowering the support pressure of the working face.
- 1
Application Research of Homogenization Mixing Equipment in Addressing Challenging Settling Characteristics of Tailings at a Specific MineAbstract:
In response to the issues of poor settling of finely-grained tailings, water overflow turbidity, and inadequate slurry homogeneity caused by polarization, a method of rapid coagulation and settling using a combination of flocculant and carbide slag is proposed in this study, using a specific mine as an example. Additionally, the stirring effect of a high-power agitator is investigated through numerical simulations. Firstly, various material tests were conducted to understand the basic physical properties and rheological parameters of the tailings. Then, optimization experiments were carried out to determine the optimal dosage of carbide slag by mixing it with the tailings.Secondly, numerical simulation techniques were used to analyze the homogeneity of the slurry after being stirred in a high-power agitator, specifically focusing on finely-grained tailings.Finally, industrial experiments were performed to validate the various dosage combinations that were determined through the earlier stages of research.The results showed that: (1) The optimal coagulant type, optimal dosage, optimal tailings slurry dilution concentration, and optimal carbide slag dosage were BKY10# coagulant, 40g/t, 10%, and 4000g/t, respectively, for the best coagulation effect. (2) The CFD technique was used to simulate the movement of the slurry in the stirring tank at various agitator speeds and different filling heights. The study revealed that the DQJ01 dual-axis horizontal high-power agitator effectively disperses the material, resulting in a superior stirring effect and significantly improved homogeneity of the filled slurry. (3) After the mine filling system was built, through debugging of the filling system, it can now be used normally with good filling effect, laying a foundation for reducing ore loss and improving the economic benefits and protecting the ecological environment of the mine.
- 1
Research on Void Filling Techniques in Metal and Non-metal Mines in High-cold RegionsAbstract:
In response to the issues of ore loss, high dilution rate, and low recovery rate caused by the sublevel caving method in the Chenqi Tianbao Xieerta Lead-Zinc Mine located in the high-cold region, a backfill mining method was proposed. Firstly, physical and mechanical property tests of the backfill material were conducted. Secondly, the actual working conditions of filling were simulated, and dynamic thickening tests of tailings were conducted to determine the optimal thickening parameters. Lastly, an industrial trial of the constructed backfill system was carried out. The results are as follows: (1) Through the backfill process experiments, the optimal types and dosages of flocculants were determined using the single-factor variable method: SNF625S anionic flocculant with a consumption of 15g/t and a slurry dilution concentration of 9.50% exhibited the best flocculation effect. (2) Based on dynamic thickening experiments, the recommended tailings feed rate was 0.78t/m2.h, resulting in an underflow concentration of 73.92%, slurry density of 2.11 t/m3, expansion of 8cm, and overflow water containing 166.8ppm of solids, meeting all the backfilling requirements. (3) After the successful construction of the backfill system in the mine, and following system debugging, the system is now operating smoothly with favorable backfilling effects. This method lays a solid foundation for reducing ore loss and dilution, improving the economic benefits of the mine, and protecting the ecological environment.
- 1
Coal Gangue Image Detection Based on Lightweight PAM-M-YOLO ModelAbstract:
This paper proposed a lightweight PAM-M-YOLO goal gangue detection model, that aiming at the problems of complex process and low detection accuracy of artificial extraction of coal gangue image features by traditional coal gangue detection algorithms. Firstly, we use MobileNetv3 feature extraction network to replace the original model backbone network, and use deep separable convolution to replace traditional convolution for feature extraction of coal gangue images. Secondly, designing a PAM parallel attention module to enhance the attention of feature map channels and spatial information after object detection network layer splicing. Finally, adding prior information to the model based on CAM activation restriction branch to reduce the local collapse of the model on non-critical features. The experimental results show that the accuracy rate, recall rate and mAP value of the lightweight PAM-M-YOLO coal gangue detection model are 98.7%, 97.5% and 98.8%, respectively. The parameter number of PAM-M-YOLO model is 3.8MB, which is nearly 1/2 lower than that of YOLOv5 model.
- 1
Research on the Temperature Rise Test Method of Mining Variable Frequency Speed Control Traction Asynchronous MotorAbstract:
The temperature rise mining traction motor is the power source of mining electric locomotives. Based on the advantages of mining variable frequency variable speed traction asynchronous motors, it has been widely used in electric locomotives with high adhesion quality. As the core component of mining electric locomotives, its temperature rise performance directly affects the safety performance and reliable operation of mining electric locomotives. However, no corresponding technical standards have been formulated for mining variable frequency variable speed traction asynchronous motors, and the temperature rise test, as one of its important indicators, has not yet formed a unified standard test method. In response to this situation, this article starts with the losses that cause temperature rise, analyzes the main factors that affect the heating of mining variable frequency speed regulation traction asynchronous motors, and combines the current situation of mining variable frequency speed regulation traction asynchronous motors, proposes a method for testing the temperature rise of mining variable frequency speed regulation traction asynchronous motors, which has been verified through experiments. This method can improve inspection efficiency, reduce inspection cycle and cost, and provide a basis for formulating relevant standards for mining variable frequency variable speed traction motors.
- 1
Study on mechanical properties of similar materials in sandstone based on orthogonal testAbstract:
Sandstone similarity simulation test is widely used in mining, civil engineering and other fields, in order to determine the ratio scheme of sandstone similar materials, the orthogonal design method were applied, the mass ratio of river sand/barite powder, gypsum/cement, cemented material/aggregate were set to 3 factor 3 horizontal orthogonal test, uniaxial compressive test and ring shear test were carried out for samples with different proportions, the compressive strength, cohesion and internal friction angle of each group ratio are measured, and the change law between each parameter and the three influencing factors of orthogonal design is studied. Analysis of test data shows that: (1) uniaxial compressive strength shows four stages of stress-strain similar to that of ordinary rock; (2) The ratio of binder material to aggregate plays a leading role in uniaxial compressive strength, and the failure form of the specimen is mainly tensile-shear composite failure; (3) The dominant role in the cohesion and internal friction angle is the ratio of the bonding material to the aggregate, and brittle fracture occurs after the failure of the ring shear specimen, accompanied by crushed stone shedding.
- 1
Experimental study on the flow characteristics and control of overburden moraine in natural caving ore drawingAbstract:
In order to solve the problem of high depletion loss caused by the inflow of fine particles of overburden moraine in natural caving ore drawing method, the indoor ore drawing similar simulation test method was adopted, and two overburden moraine states of natural accumulation and consolidation modification were selected for test, and the mixing rate of fine particles during ore drawing was statistically analyzed. The research results showed that: In the state of natural deposit overburden, the mixing rate increases with the height of ore drawing, and the mixing rate is proportional to the content of fine particles in the overburden. The deposit under the moraine overburden can be divided into four stages: pure ore discharge, a small amount of fine particles and a small amount of fine particles and a large amount of fine particles. In the state of consolidated moraine, the fine particle mixing rate can be reduced by more than 50%, and the ore output can be increased by 30%. Consolidation modification is an effective means to control the fine particle mixing of the covered moraine.
- 1
Study on the spatial distribution of burst pile block degree based on TAUNet segmentation modelAbstract:
In order to better meet the need for real-time and high-precision detection of burst pile blockiness in mining sites, a deep learning-based burst pile block segmentation model TAUNet (Transformer Aspp UNet) is proposed, which incorporates Transformer"s self-attentive mechanism in the encoder and decoder of UNet, using Transformer"s self-attentive mechanism to handle large feature mappings, improve the extraction of global information and recover granular details that are skipped in the encoder. In the backbone network feature extraction stage, the ASPP null convolution module is incorporated to enhance the model for block local feature fusion. On the basis of the burst image segmentation, a burst layering method is used to obtain the block degree spatial distribution information of the bursts. The experiments show that (1) the segmentation model has good segmentation performance, and the model training evaluation indexes Dice, IoU and Recall reach 97%, 95% and 96% respectively, which are all better than the mainstream semantic segmentation network, and have good segmentation effect for the on-site blast pile blocks; (2) the spatial distribution of the blast pile blocks from 300 m to 315 m in the west mining area of the large row mine can be known by the method of blast pile layering. 87.68% of the block size distribution in the 0 ~ 0.6 m, 9.9% of the block size distribution in the 0.6 ~ 1 m, greater than 1 m of large blocks accounted for 1.8%. Therefore, the blast pile segmentation model based on TAUNet and the method of blast pile stratification can provide data guidance for the development of refined and intelligent blasting effect evaluation.
- 1
Research on the Surrounding Rock's Control Technology during Deep-hole Blasting and Roof Cutting along the Hollow Stays in Thick Coal SeamsAbstract:
In order to address the unjustified issues with the current top-cutting parameters and filling wall parameters, this study uses the N1302 operating face of the Gucheng coal mine as its research backdrop. Its goal is to optimize the deep-hole blasting top-cutting scheme along the hollow path in thick coal seams. In order to lower the pressure and ensure the stability of the roadway in the air, theoretical calculations, numerical simulations, and field applications are used in combination. This research focuses on the characteristics of the mine pressure along the air when the roof is not cut, the theory and practice of deep hole blasting roof cutting and pressure relief, and the height and angle of the blast. Employing a numerical simulation of the UDEC, examine the characteristics of the roadway's deformation and stress distribution under the influence of various roof-cutting heights and angles. The properties of tunnel deformation and stress distribution under various roof cutting heights and angles are examined through numerical modeling using UDEC. Based on the results of numerical simulations, the deformation of the roadway and the filling body's support resistance increase continuously as the roof cutting angle increases, while they decrease initially and then stabilize as the roof cutting height increases. The optimal roof cutting parameters in this study are 20.5m in height and 5° in angle, taking into account safety and coal mining efficiency considerations. According to field application results, deep hole pre-cracking blasting of the top plate can better maintain the stability of the roadway along the air stay because the top and bottom plates move closer after cutting them by 1250mm and 730mm, respectively, and the two gangs move closer by 900mm and 450mm, respectively. Additionally, this study offers technical assistance for stabilizing the roadway as well as top-cutting and decompression operations along the thick seam.
- 1
Research and Application on Optimization of Deep Hole Blasting Parameters in XitieshanAbstract:
The blasting parameters of the mining site directly affect the degree of fragmentation of the ore body and are an important part of underground mining of metal mines. Reasonable blasting parameters can not only effectively reduce the loss rate and dilution rate of the mining site, but also have significant implications for improving mining efficiency and reducing mining costs.Currently, the optimization of blasting parameters is mostly determined through theoretical calculations, engineering analogies, and other methods, but its applicability in practical production is not strong.The blasting funnel test is currently the most practical method for determining blasting parameters, but there are differences between the use of emulsion explosives in the test and the use of ammonium nitrate explosives in actual (medium) deep holes, resulting in certain differences in results.In response to the difficulty in determining the parameters of (medium) deep hole blasting, powder charges were used instead of emulsified charges to conduct blasting funnel tests. The parameters of (medium) deep hole blasting hole network were determined through experimental results, comprehensive theoretical calculations, and engineering analogies.Through on-site parameter application, the unit consumption of explosives was reduced by 9.86%, and the amount of ore collapse per meter was increased by 9.92%, resulting in significant economic benefits.
- 1
Systematic Design and Practice of Mining Expansion in Wulan Lead-zinc MineAbstract:
Achieving stable production capacity in mines is a crucial and complex system engineering and management issue. This paper uses the Wu lan lead-zinc mine as the engineering background, on the basis of systematic investigation and analysis of the factors that its long-term production capacity is not up to standard, through the use of large-diameter deep-hole stage empty field subsequent filling mining method, supporting the construction of full tailings sand cementation filling system, optimization of double ramp development system, upgrading underground shovel to transport mining equipment and other technical transformation means , the production capacity of underground single stope was increased to 1000t/d, the efficiency of mining, loading and transportation was improved by about 60%, the production capacity of Wu lan lead-zinc mine was increased from 2000t/d to 3000t/d, the direct mining cost was reduced by 16% after technical transformation, and the average annual profit was about 178 million, which achieved the remarkable effect of reducing costs and increasing efficiency. The practice of mine capacity improvement can provide effective reference for the capacity optimization of similar mines at home and abroad.
- 1
Research on Deep Deashing Technology of Anthracite by Flocculation Enhanced FlotationAbstract:
The added value of coal increases with the decrease of ash content, but the deep deashing technology of coal has not been applied in industry. The test takes anthracite coal as the research object, using flocculation enhanced flotation method to carry out deep deashing. The mechanism of flocculation was investigated based on the experimental results of particle size, XRD and contact Angle. The influence of pulp concentration, collector dosage, foaming agent dosage and flocculant dosage on flotation effect was investigated by single variable method. The test results show that: When the slurry concentration is 80g/L, the amount of collector is 2kg/t, the amount of foaming agent is 1kg/t, the amount of dispersant is 2kg/t and the amount of polyoxene is 5g/t, the flotation effect is the best. Compared with the traditional flotation method, the flocculation-enhanced flotation method can obtain a higher recovery rate of cleaned coal combustible and a lower ash content of cleaned coal. The ash content of raw coal is reduced from 10.15% to 1.98%, and the flotation efficiency is improved. It has certain reference value for the industrial application of coal added value.
- 1
Optimization of Stope Structure Parameters Based on Mathews Stability Diagram Method and FLAC3DAbstract:
With the increase of mining depth, the mine will face more uncertain factors in the production process. Reasonable design of stope structural parameters will effectively reduce the occurrence of stope roof fall accidents. In order to determine a reasonable and unified range of stope structural parameters, this paper adopts Mathews stability diagram method and numerical simulation to study the structural parameters of deep stope in Gaofeng Mine, and analyzes the ultimate blasting area, stress cloud map, displacement cloud map and plastic division map under different stope structural parameters. The results show that when the stope width is 8m, the limit exposed area is 400m2; When the mining method is simultaneous mining, it is recommended that the width of the stope be less than or equal to 8m for both the layering height 4m and 12m. When advanced mining is adopted, the maximum value of the maximum main stress of the stope exceeds the safety warning line. Therefore, in order to ensure the safety of the mining process, it is recommended that the stope structure parameters are as follows: the width of the stope should be less than or equal to 8m, the range should be 7-8m, the stope length should be the thickness of the ore body, about 40m, the layering height should be 4m to 12m, and the mining method should be simultaneous mining.
- 1
Research on the Influence of Medium and Deep Hole Blasting on Artificial False Roof in StopesAbstract:
In order to analyze the damage of blasting stress wave to artificial roof, the stability of artificial roof under blasting action is explored. LS-DYNA simulation dynamic analysis software was used to calculate the disturbance and damage of 4.75m thick artificial false roof by medium and long hole blasting. The results show that during the propagation of stress waves from the bottom of the hole to the free surface of the hole opening, the blasting stress gradually decreases, and the distribution is uniform in the artificial false roof, with fast attenuation. After leaving a 0.5m protective layer at the top, the maximum effective stress value of most units of artificial false roofs is less than the plastic zone failure stress of the filling body, indicating that the blasting effect has little impact on the damage of artificial false roofs and the safety of artificial false roofs is still high. Based on the simulation results, on-site blasting tests were conducted and displacement monitoring points were set up at key positions of the artificial false roof. The test results showed that after medium deep hole blasting, the artificial false roof and side walls did not collapse or fall, the roof settlement was reasonable, and good blasting effects were achieved.
- 1
Permeability evolution characteristics of key water barrier layer under water-mechanical couplingAbstract:
The key layer of water barrier has great influence on the safe mining of coal seam under water body and aquifer. In order to study the permeability evolution law of the key layer and the water retention performance of the mining key layer, the water-force coupling seepage test and the numerical simulation test of the water retention performance of the key layer were carried out on the background of coal mining under the reservoir of 15130 working face of Xin "an Coal Mine. The results show that: (1) the permeability coefficient-strain curve of the key layer under load-bearing compression can be divided into four stages, which correspond to the compaction stage, elastic stage, plastic stage and failure stage in the stress-strain curve; (2) The change of confining pressure in the compaction stage is more likely to cause the change of the permeability coefficient of the key layer. In the range of 1~2MPa, the water pressure is not positively correlated with the permeability coefficient. (3) The key layer above the 15130 working face is bent and deformed under the influence of mining, but on the whole, the key layer still has good water insulation performance. The results can be used for reference for coal mining under water bodies.
- 1
Experimental Study on Dynamic Compressive and Energy Characteristics of Yellow Sandstone under Freeze-thaw CyclesAbstract:
In order to investigate the dynamic compressive and energy characteristics of yellow sandstone under freeze-thaw cycle. The dynamic compression test of yellow sandstone samples with freeze-thaw cycles of 0, 10, 20 and 40 times was carried out by using 50mm diameter Hopkinson pressure bar. The dynamic compression strength, energy dissipation and failure pattern of yellow sandstone under impact load are obtained. The results show that with the increase of impact pressure and loading rate after freeze-thaw cycle, the degree of breakage of yellow sandstone increases and the number of small fragments increases. With the increase of the number of freeze-thaw cycles, the crushing degree of the yellow sandstone after impact will also increase. The dynamic compressive strength of yellow sandstone specimens with the same number of freeze-thaw cycles increases with the increase of strain rate, which is approximately linear and positive correlation, and has obvious strain rate effect. The dynamic compressive strength of yellow sandstone specimens with the same impact pressure increases first and then decreases with the increase of the number of freeze-thaw cycles, which has obvious freeze-thaw cycle effect. The dissipated energy of the specimen increases with the increase of the strain rate, and the energy dissipation rate also increases, which is an approximate power function relationship. The dissipative energy of the samples has a significant freeze-thaw cycle: with the increase of freeze-thaw cycles experienced by the yellow sandstone, the dissipative energy has a trend of first increasing and then decreasing, and the overall trend is decreasing, showing a negative correlation
- 1
Development law and Failure Characteristics Analysis of Prefabricated Shallow Cracks in Rock-Like Specimens under Unidirectional StressAbstract:
In the mining process of southwest mining area in China, the fracture development of overlying rock is significant, the mining disturbance is strong, and the control of surrounding rock is difficult. In order to study the failure mechanism of fractured rock and improve the control effect of surrounding rock in southwest mining area, uniaxial compression test combined with DIC technology was used to study the influence of fracture dip angle and number on the mechanical properties, surface deformation field and fracture propagation path of rock-like specimens. The results show that the decrease degree of uniaxial compressive strength of rock increases from 12.47 % to 28.83 % and 16.66 % to 28.83 % respectively during the change of fracture inclination angle from 0 ° → 45 ° and 90 ° → 45 °. The average peak strength of single fracture specimen is 80.24 % of the peak strength of complete specimen, the average peak strength of double fracture specimen is 69.07 % of the peak strength of complete specimen, and the average peak strength of three fracture specimen is 56.94 % of the peak strength of complete specimen, which provides a basis for controlling the stability of surrounding rock in southwest China.
- 1
Study on pillar recovery scheme and stope structure parameter optimization of a molybdenum mineAbstract:
In the early stage of a molybdenum mine, the shrinkage method was used for mining, and a large number of top pillars and interlayer pillars remained in the mining area. To avoid resource waste, the mining plan for the pillars was studied. By comparing the economic and technical indicators of various mining methods, it is finally determined to use segmented rock drilling and segmented filling mining method to recover the inter pillar when the upper part of the pillar is the ore body, and to use segmented rock drilling and segmented filling mining method with reserved top pillar to recover the inter pillar when the upper part of the pillar is the filling body; It is recommended that the mine adopt the segmented rock drilling and segmented filling mining method to recover the top pillar under the condition that the previous middle section is not filled; Based on the selected mining method, the length of the stope and the thickness of the reserved top pillar were optimized using FLAC3D software. The stress and displacement distribution of the surrounding rock and filling body around the stope with different structural parameters were analyzed, and it was determined that a stope length of 50m and a reserved top pillar of 5m were more reasonable; During the application period, the pillar recovery plan brought about 4705200 yuan in economic benefits to the mine, which can provide a reference basis for pillar recovery in similar mines.
- 1
Study on Preparation and Properties of Coal Gangue-Desulfurization Gypsum-Fly Ash Paste SlurryAbstract:
In order to ensure that the coal gangue paste composite filling slurry meets the requirements of mine pipeline transportation performance, the coal gangue, desulfurized gypsum and fly ash are used to develop the paste composite filling material. Taking the fine gangue rate, coal gangue content and fly ash content as the research objects, the orthogonal test of three factors and four levels is carried out to explore the changing rules of slurry flow performance, workability and rheological properties. The Hershel-Bulkley model is used to fit the rheological parameters of coal gangue-based paste composite filling slurry. The correlation coefficient R2 is 0.999, and the model fitting accuracy is high and the reliability is strong. The results show that the slump, diffusivity, fluidity, consistency and bleeding rate of slurry increase first and then decrease with the increase of fine gangue content. When the fine gangue content is 40%, the pumpability of slurry is the best. The content of coal gangue has no significant effect on the pipeline transportation performance of slurry, but the kaolin phase in coal gangue will adsorb a small amount of free water, resulting in poor flow performance of slurry. Fly ash plays the role of ball lubrication and micro-aggregate in the paste slurry system, releasing a large amount of free water, thickening the water film on the surface of the particles, and improving the pipeline transportation performance of the slurry. However, when the fly ash content exceeds 35%, the agglomeration of fine particles of fly ash is serious, which enhances the ability of the slurry to resist shear deformation and weakens the flow performance and rheological properties of the slurry.
- 1
Analysis of Energy Consumption Characteristics of Rock Breaking during Rotary Drilling ProcessAbstract:
Obtaining drilling parameters for energy consumption analysis is an important link in achieving efficient drilling, in order to explore the correlation between drilling parameters and energy consumption during rock breaking during rotary drilling. Exploring the influence of drilling parameters on drilling speed through indoor drilling experiments; Establish a new energy time density index and analyze the energy consumption characteristics during the process of rotating rock breaking through numerical simulation. breaking energy density is established. The energy density first decreases and then increases with the increase of axial pressure and rotational speed. When the energy density is concentrated at 0.0069 J/mm3.s-1, the energy consumption is the lowest and the drilling efficiency is the best.
- 1
Influence of Inflation in Vortex Finder on the Separation Effect ofWater-only CycloneAbstract:
In order to improve the separation effect of the water-only cyclone, an inflatable device was set up at the top of the vortex finder of the water-only cyclone to constitute a new type of inflatable water-only cyclone. The test of the effect of the inflating volume and feeding pressure on the separation effect of the inflatable wa-ter-only cyclone was carried out; the ANSYS FLUENT software was used to simulate the flow field inside the inflatable water-only cyclone with the inflating vortex finder. The experiment results show that, after the vortex finder is inflated, the ash content of the overflow is basically unchanged, and the ash content of the underflow with 0.5-0.25 mm particle size increases from 51.80% to 72.75%, which indicates that the in-troduction of gas has a promoting effect on the separation effect. The simulation results show that the air column in the cyclone is disappeared after the vortex finder is inflated, and the fluid flow streamline in some area of the cyclone is changed, and a new separation zone appears in the cone area at the top of the underflow apex. By comparing the results of experimental and simulation, it can be concluded that the increase of the actual separation space in the cyclone, the change of the fluid flow characteristics and the enhancement of the cone part separation effect are the main reasons for the increase of the separation effect of the water-only cyclone after the vortex finder is inflated.
- 1
Improved Extreme Learning Machine for Coal and Gas Prominence PredictionQiao Weihao, 安葳鹏, 赵雪菡, 吕常周
Abstract:
To improve the accuracy and efficiency of coal and gas protrusion prediction, a coal and gas protrusion prediction model based on data preprocessing multi-strategy Improved Fireworks Algorithm (IFWA) Optimized Extreme Learning Machine (ELM) was proposed. First, feature selection is performed using grey correlation analysis (GRA) for the nonlinear multidimensional feature data. Feature approximation is performed using principal component analysis (PCA), and the data preprocessed data metrics are used as inputs to the model. Secondly, in order to solve the problem that the fireworks algorithm (FWA) was easy to fall into the local optimum, this paper introduced the gravitational search operator and the hybrid variational operator multi-strategy to improve the fireworks algorithm. Finally, the weights and deviations from the input layer to the implied layer of the ELM are optimized using the multi-strategy Improved Fireworks Algorithm (IFWA) to construct the optimal gas protrusion risk prediction model. The results show that the RMSE and R2 of the IFWA-ELM model could be up to 0.074 and 0.968, which are improved compared with the models such as ELM and FWA-ELM. The IFWA-ELM model can classify up to 100% of the prediction of coal and gas protrusion with better convergence speed and prediction accuracy. It provides a reliable theoretical basis for the prediction of coal mine gas protrusion multi-data fusion.
- 1
Simulation study on shear failure of anchored jointed rock mass under dynamic impact loadingAbstract:
In order to explore the influence of different joint angles on the shear failure of anchored jointed rock mass under impact dynamic load, the dynamic shear numerical simulation of anchored rock mass with different joint angles under dynamic load impact is carried out based on ABAQUS software. The shear failure evolution process of anchored jointed rock mass under dynamic load impact and the shear strain, shear stress and shear displacement of anchor rod when shear failure occurs are systematically analyzed, and the optimal anchoring angle scheme is proposed based on theoretical analysis. The results show that in the process of dynamic load impact, the bolt and rock mass provide different degrees of shear resistance of anchorage system in different impact periods. When the joint angle of the anchored rock mass is 60 °, the shear strain generated by the shear failure of the bolt is the largest, the shear stress and shear displacement are the largest, followed by 90 °, and the smallest is 45 °.Therefore, the order of shear capacity of the three is 60 ° > 90 ° > 45 °. The optimal anchorage angle is also verified in the range of 60 ° -70 ° by the optimal anchorage angle estimation formula. The research results have certain guidance and reference significance for the reinforcement engineering of jointed rock mass in dynamic roadway.
- 1
Selection of mining methods for complex and difficult-to-mine orebody in the west depression of KafangAbstract:
Aiming at the complex structure and poor solidity of the surrounding rock of the ore body in Kafangxi concave mine section, through engineering geological investigation, we classified and counted the production, storage conditions and grade of the ore body, and partitioned the ore body in combination with the actual situation of the mine. Under the condition of establishing the comprehensive evaluation index system of mining program, combining the correlation matrix method and mining theory, it comes to the conclusion that the optimal mining program for rich ore bodies and richer ore bodies is the upward layer filling method, and the optimal mining program for poorer ore bodies is the segmented empty field method. After the application of the actual project, the comprehensive loss depletion rate of the quarry was reduced to less than 15%, the production cost of the quarry was reduced by 10% compared with the previous one, and the comprehensive production capacity in the mining section reached 350t/d.
- 1
Prediction and control scheme simulation of groundwater pollution transport around an iron tailings reservoirAbstract:
In order to effectively control the groundwater pollution around an iron tailing reservoir and reveal the migration law of heavy metal iron ions in groundwater affected by rainfall and permeability coefficient, taking an iron tailings reservoir in China as an example, a solute transport model of heavy metal iron ions in the study area was established based on Visual Modflow to simulate the migration and diffusion process of metal iron ions in groundwater under abnormal working conditions. The control effect of surface hardening and the addition of impervious wall on pollutant transport is simulated. The results show that the migration velocity of iron ion increases with the increase of rainfall and permeability coefficient. Surface hardening and the addition of cutoff wall can effectively control the influence of heavy metal iron ion leakage on downstream villages, but the effect of adding cutoff wall is better.
- 1
Study on Measurement Method of Dust Concentration in Blasting Area Based on Image TechnologyAbstract:
In view of the difficulty of dust early warning management in blasting area, a method of dust concentration measurement in blasting area based on image technology is proposed. Based on the dust concentration information of dust images and typical measurement points in the blasting area, the Gaussian filter noise reduction method has been selected and the gray level α has been optimized as 128 to effectively identify the boundary between the dust area and the background area, and improve the accuracy of the dust image by using the image technologies such as the noise reduction, enhancement and segmentation of the dust image. The function of dust concentration and dust image gray value in the explosion area has been established as C= -0.01157G2 +2.342G-104.1 in order to accurately measure the dust concentration in the mine explosion area. The application results show that the dust concentration in the burst zone reaches the peak 13.824mg/m3 in 7s and decreased to 3.749 mg/m3 at 90s after blasting. And what’s more, the high concentration dust cloud within 3m~52m from the surface is at the left rear position of the burst zone and its influencing area is 110m×60m.The high concentration dust cloud above 52m from the surface is at the upper right of the burst zone and its influencing area is 59m× 56m at the 90s.At the 90s after blasting, the high concentration dust clouds concentrated above 40m from the surface its influencing area is 120m ×67m. The application results consistent with the actual situation and the effectiveness of this dust measurement method is verified.
- 1
Difficulty Evaluation and Treatment Application of Geological Environment Restoration in Open-pit Limestone MinesHAO Jie, 李洪涛, 安成龙, 赵振伟, 韩琳, 王宏伟
Abstract:
As an important part of ecological civilization construction, ecological restoration of abandoned open-pit limestone mines is of great significance to scientifically classify zoning and propose targeted treatment plans. Based on the basic principles of AHP (Analytic Hierarchy Process) and fuzzy mathematics, the evaluation index system of geological environment restoration difficulty of abandoned open-pit limestone mine is constructed, and the research method of index weight determination by improved AHP and fuzzy comprehensive evaluation is put forward. Taking Lijiawo Mine in Jinan City, Shandong Province as the research area, the geological environment restoration difficulty evaluation and treatment plan are carried out. The results show that in the evaluation index system, slope inclination, distribution of dangerous rock mass and slope height are the key indexes, with weights of 0.360, 0.194 and 0.184, respectively. The areas with great difficulty for geological environment restoration in the study area mainly include high and steep slopes and dangerous rock mass distribution. According to different zones, the corresponding treatment schemes of dangerous rock mass treatment, residual hill cleaning and slope greening are put forward. It can provide reference for difficulty evaluation of geological environment restoration and zoning treatment of open-pit limestone mine.
- 1
Study on Shear Mechanical Properties of Structural Planes under Relative Normal ForcesAbstract:
The magnitude of the normal force has an important influence on the Shear strength of the rock mass discontinuity, but there is no clear boundary for the division of the magnitude of the applied normal force. In view of this, this article proposes the ratio of normal force to uniaxial compressive strength as a coefficient to measure the relative magnitude of normal force, and applies pfc2d to simulate shear experiments on structural planes with relative normal force under different roughness levels. The results show that the experimental results are basically consistent with the three line Shear strength theory; When the relative normal force is less than 0.06, the growth rate of shear strength is the highest, and the growth rate rapidly decreases with the increase of relative normal force; When the relative normal force is less than 0.5 and greater than 0.06, the decreasing trend of the shear strength growth rate becomes slower; When the relative normal force is greater than 0.5, the growth rate of shear strength is basically stable. Based on the three line Shear strength theory and the shear strength formula under medium normal stress, two sets of strengthening index curves were obtained. By comparing the change trend of curves under different materials, the rationality of the upper and lower limits was verified.
- 1
Hard Roof Control Technology of Extra Thick Coal Seam Overburden with Varying Spacing in Zhuxianzhuang Coal MineAbstract:
The lagging collapse of the massive and hard roof poses a significant threat to the mining face, which typically employs pre-split blasting to reduce the span of the roof. Based on the management of the thick conglomerate roof at the 883-1 coal face of the ZhuXianzhuang coal mine in Huaibei Mining Group, key control areas of the massive roof were identified based on the distance changes between the coal seam and the thick conglomerate. On the basis of the structural analysis of the extra thick coal seam roof strata, the given load of the roof was analyzed, the influence of the variation of the interlayer distance on the mining pressure was analyzed, and the selection of the roof control target layer was guided, and the parameters of the borehole spacing were determined. By using high-performance coal mine water-gel explosives combined with multidirectional cumulative tubes and grouting sealing technology, the practice of deep hole blasting technology for hard roof was carried out, and the deformation of the mining roadway surrounding rock and the manifestation of mining pressure at the working face were effectively controlled.
- 1
Study on Optimization of Coal Caving Process in Fully Mechanized Caving Face of Suancigou Coal MineAbstract:
Taking the 6 upper 108 working face of Suancigou Coal Mine as the research background, in order to optimize the coal drawing process of the fully mechanized caving face in the extra-thick coal seam of Suancigou Coal Mine, improve the top coal recovery rate of the working face and reduce the mixed gangue rate. By using PFC 2D particle flow software, the numerical model of coal caving in working face is established, and the field test of five different coal caving processes is carried out. The following conclusions are drawn : when the thickness of coal seam is more than 20 m, the effect of group mul-ti-round coal caving technology is the best ; when the thickness of the coal seam is less than 20 m, the two-wheel interval coal drawing process is the most reasonable. The research results improve the top coal recovery rate and reduce the mixed gangue rate in the fully mechanized caving face of Suancigou Coal Mine, which can provide theoretical and practical support for the fully mechanized caving face of thick and extra-thick coal seams with similar conditions in the northwest region.Keywords: extra-thick coal seam; coal drawing process;recovery rate
- 1
Study on the Influence of Surface Drilling Extraction on the Danger Area of Spontaneous Combustion in GoafAbstract:
In order to study the influence of surface drilling extraction on the danger area of spontaneous combustion of goaf coal, based on the fully mechanized mining face of a mine as the research background, the situation of spontaneous combustion danger area and air leakage in goaf of coal left in goaf was determined by using beam tube monitoring system and SF6 tracer gas method.Through numerical simulation, the distribution of spontaneous combustion danger zone in goaf and the influence of different extraction volume of surface drilling on goaf are studied.The research results show that the maximum width of goaf oxidation zone is 72.2m, and the daily minimum advance is 1.08m.The ratio of the maximum concentration of SF6 between the measuring point of wind alley and the measuring point of surface drilling was 8:1.The numerical simulation results show that surface drilling and extraction increase the range of spontaneous combustion risk area in goaf, and the spontaneous combustion risk area expands with the increase of extraction amount.
- 1
Study on Ore-rock Movement Characteristics and Influencing Factors in Inclined OrepassAbstract:
The orepass is an important project for mine rock transportation. The damage of the sidewall caused by the unloading impact is the main problem that restricts the age limit of the orepass. Fully understanding the movement characteristics of the ore-rock in the orepass and its impact position with the sidewall is an important basis for optimizing the orepass design and support scheme. Inclined orepass is one of the layout forms of mine orepass at home and abroad. In order to analyze the movement process of ore-rock in inclined orepass, PFC numerical simulation experiment and physical similarity experiment are used to simulate the unloading process of inclined orepass, analyze the movement form and velocity variation characteristics of ore-rock in inclined orepass, study the influence of inclined angle of orepass on the movement law of ore and rock and the position of hitting sidewall, and discuss the difference of movement mode of ore-rock in vertical orepass and inclined orepass. The study found that: (1)When the inclination angle of the orepass is 60°, the two impact heights of the ore-rock block are 1.36m and 3.30m away from the discharge side, the impact velocity is 9.53m/s and 5.47 m/s, respectively, and the peak speed of the ore-rock block reaches 16.17 m/s when it reaches the orepass floor. The process of ore-rock movement can be simplified into five stages: uniform accelerated sliding or rolling in the branch orepass, oblique throwing movement at a certain initial speed from the orepass, two collisions with the sidewall, uniform accelerated sliding or rolling movement along the sidewall, and finally reaching the bottom plate of the orepass. (2)The influence of chute inclination angle on the movement process of ore and rock is very significant. With the increase of chute inclination angle, the distance between the position of ore and rock hitting the sidewall twice and the height of the unloading port shows an increasing trend. After the inclination angle exceeds 60°, the distance between the position of the second impact and the height of the unloading port and the impact velocity increase sharply. (3)Compared with the vertical orepass, the movement process of the ore-rock in the inclined orepass is more significantly restricted by the boundary of the sidewall, and the falling body movement time is shorter. There is a relatively long distance between the ore-rock and the sidewall, and the sliding process causes friction damage to the sidewall.
- 1
Effect of Fracture Angle on Coal-rock Mass Cracked by High-voltage Pulse in WaterAbstract:
In order to explore the effect of fracture dip angle on the effect of high-voltage electric pulse fracturing coal-rock mass in water, the cracking test of true triaxial water high-voltage electric pulse cracking in water was carried out by using similar samples of coal-rock mass with precast central hole and parallel precast fracture, and the crack propagation characteristics were analyzed based on the test results. The meso-parameters of the particle flow program were calibrated by the experimental results, and the influence of fracture inclination on the crack growth characteristics was further studied.The results show that under the action of confining pressure, the stress in the area between the parallel fractures is reduced, and stress concentration occurs at both ends of the fracture, and the cracks are more likely to occur in the stress reduction area and extend to the stress concentration area under the action of impact load. With the increase of fracture inclination, the crack length and width show a trend of first increasing and then decreasing due to the consumption of stress wave energy by the fracture. Under the action of electrical pulse, the specimen first generates microcracks at the central hole, at both ends of the prefabricated crack and the inside of the prefabricated fracture, and with the reflection and diffraction of the stress wave at the fracture, the stress concentration area is transferred, and the microcrack develops into a macroscopic crack in this process, so that the crack communicates with the central hole. The research results provide a basis for the engineering application of high-voltage pulse cracking technology and the reasonable selection of drilling position.
- 1
Study on mechanical properties and energy evolution of saturated limestone under cyclic loadingAbstract:
In order to study the mechanical characteristics and deformation laws of coal seam floor limestone under hydraulic coupling and prevent the instability and failure of coal floor caused by engineering disturbance, the conventional triaxial compression test and cyclic loading and unloading test of water-saturated limestone under different confining pressures were carried out based on TC-200 microcomputer servo multi-field coupling system of rock. The stages of total stress-strain curve of rock are divided by volume strain and crack strain. The failure mechanism of rock under cyclic load is studied from the view of energy dissipation and cumulative damage. The results show that: (1) under cyclic loading and unloading conditions, the entire stress-strain curve of the rock can be divided into five stages, namely, the compression and closure stage of the original micro-fracture, the linear elastic compression stage, the stable development stage of the fracture, the unstable development stage of the fracture and the deformation and failure stage after the peak. (2) Under the condition of constant confining pressure, the peak strength of rock sample under cyclic loading and unloading test is lower than that of conventional triaxial test, and the overall strain variable increases with the increase of unloading level, and the dilatancy phenomenon is gradually significant; (3) Under confining pressure and cyclic load, shear failure is the main failure mode of saturated limestone. When confining pressure increases, transverse and longitudinal tensile failure occurs gradually. (4) With the increase of cycle level, the total energy increases nonlinear, and the proportion of dissipated energy increases gradually. Under the same cycle level, with the increase of cycle number, the dissipated energy shows a slight decrease trend; (5) With the increase of unloading level, the rock damage behavior becomes more active, but the rock damage gradually tends to be stable in the same grade cycle, which is basically consistent with the evolution law and mechanism of dissipated energy.
- 1
Source identification technology of near-surface borehole water gushing based on hydrochemical characteristics analysisAbstract:
The mine water disaster seriously restricts the production of the mine. It is of great practical significance to determine the source of the water inrush for the safe production of the mine. Taking the near-surface wall of inclined shaft in Shuiyindong Gold Mine as the research object, on the basis of analyzing the mechanism of water inrush, the fuzzy comprehensive discriminant method and grey correlation degree theory combined with six hydrochemical indexes are used to identify the source of mine water inrush. The results show that : ①The discriminant model is used to analyze and process the data of each water sample. Through the analysis and judgment of membership relationship and correlation degree, it is concluded that the water source of the gushing water is atmospheric precipitation.②By analyzing the mechanism of water gushing, it is found that the water channel of the inclined shaft near the surface is mainly the fracture zone, and the main source of water gushing is atmospheric precipitation. ③The hydrogeological conditions of the Shuiyindong gold mine are relatively complex. The conventional hydrochemical characteristics combined with the discriminant model are used to identify the source of the gushing water, which effectively avoids the occurrence of inaccurate or even misjudgment of the judgment results, and is conducive to the rapid, economic and accurate identification of the source of the gushing water. The research results provide a theoretical basis for the identification of mine shaft water source and the prevention and control of mine water disaster under similar conditions.
- 1
Effect of fiber length and content on strength characteristics of waterproof grouting material in Xiyu Coal mineAbstract:
For promoting the application of waterproof grouting material and improve its mechanical properties, waste glass fiber was used to modify the material. The effects of fiber length, dosage and curing time on strength were investigated through compression tests, and the mechanism of glass fiber was discussed based on structural damage analysis and microscopic images. The results show that the uniaxial compressive strength and tensility of waterproof grouting material increases significantly by adding glass fiber. The growth rate of strength decreased with the increasing curing time. The rapid growth period is ranging from 0 to 3 days and the stale period is after 3 days. The fiber length has a significant effect on the strength index, and the contribution value of cut fiber to the strength increase is the highest. With the increase of fiber content, the compressive strength and flexural strength increased first and then decreased, and the maximum strength was reached when the fiber content was 0.3%~0.4%. The bridge effect of fiber in cement mortar can inhibit the expansion of compression crack, buffer the failure of specimen. However, when the fiber content is too high or the length is too large, there will be entanglement, connection, aggregation and clumping, which increases the porosity of local areas and weakens the mechanical properties of waterproof grouting material.
- 1
Damage characteristics and crack expansion pattern of water-bearing coal rock assemblage under cyclic loadingAbstract:
The coal rock mass and waterproof coal column of the 8105 working face of Tongxin Coal Mine have been subjected to hydration for a long time, and the cyclic load disturbance such as mine earthquake and mining stress is obvious, and this working face is now used as the research background, the uniaxial and cyclic loading and unloading tests of three different top and bottom slate lithology (mudstone, sandstone and limestone) under different moisture cuts were carried out in the laboratory. The damage deterioration mechanism and energy evolution law were obtained through mechanical test analysis, and the damage law of cracks from microscopic to macroscopic was revealed based on electron microscopy scanning, digital speckle and RFPA numerical simulation. The results show that: (1) With the increase of moisture content, the peak strength deterioration amplitude of the coal-rock composite specimen gradually decreases, the peak axial strain of the specimen with the water saturation percentage in the four stages gradually decreases, and the stage deterioration amplitude is greater under cyclic loading and unloading conditions than under the single-axis compression condition, and the deterioration degree in N20, S20 and SH20 shows the law of N20> S20>SH20. (2) Under the action of water immersion, the degree of cementation of the structural surface of the coal rock mass decreases, and it becomes weak from dense. Under the condition of cyclic loading and unloading, the failure mode of the combination gradually changes from tension-splitting failure to tensile-shear mixed failure with the increase of rock-coal strength ratio. (3) Based on RFPA simulation analysis, with the increase of lithological strength of the top and bottom slate under cyclic loading and unloading, the main fractures formed by the rupture of the assemblage gradually become obvious, the derivative secondary fractures gradually decrease, and the coal rock assemblage with higher strength under hydration can still maintain stronger brittle failure when it fails.The research results can provide certain theoretical guiding significance for the safe production of water-rich working surfaces.
- 1
A practical study on the integrated technology of curtain grouting in through layer boreholes in Yongxia mineAbstract:
After many rounds of gas extraction drilling in the bottom pumping lane of Chen Silou coal mine, the surrounding rock of the roadway produces more fissures leading to poor sealing of the drilling holes, which affects the effect of gas extraction, and in response to this problem, curtain grouting technology is selected to reinforce the roadway. Firstly, a numerical model of solid coal rock borehole grouting was established by COMSOL Multiphysics software, and according to the numerical simulation results, the diffusion law of the grouting slurry in the fissure rock was analysed, and the suitable grouting process was designed, and then the experimental research of the drilling integrated curtain grouting and grouting integrated sealing grouting process was carried out in the field. The results show that curtain grouting measures can effectively seal the fissures and increase the gas extraction concentration. Compared with the non-curtain grouting drill holes, the average initial pumping concentration of a single hole increased by 1.14 times, and the average re-pumping concentration of a single hole increased by 1.23 times. This technology provides a technical reference for curtain grouting projects in similar mines.
- 1
Research on Underground Unmanned Vehicle Target Detection Based on Inverted ResidualAbstract:
Under the influence of special working conditions such as dim underground light, uneven lighting, and complex background, the formed image targets have problems such as few detailed features and blurred images. This paper proposes a detection algorithm based on inverted residual structure to improve the YOLOv5s model to solve the problem of low detection accuracy of underground targets. Firstly, the backbone network introduces the Channel Attention Neural Network (SE Net) module to better handle issues such as dim underground light and blurred images, thereby improving detection accuracy; The neck network introduces an inverted residual structure in the BottleneckCSP module, expanding the channels to enrich the number of features and further improve detection accuracy. The results of detection experiments on a self built underground dataset show that the average detection accuracy of this model (when the intersection to parallel ratio is 0.5) reaches 84.3%, which is 16.7% higher than the YOLOv5s model and a 17.1% reduction in parameter quantity. Therefore, this model is lightweight and has high accuracy, which can effectively improve the problem of low accuracy in underground target detection and basically meet the needs of underground unmanned vehicle target detection.
- 1
Research on Reliability Evaluation Model of Ventilation System in Underground Metal MinesAbstract:
In response to the characteristics of fuzziness and randomness in the reliability of ventilation systems in underground metal mines, as well as the complex evaluation index system and the difficulty in dealing with the mixed storage of quantitative and qualitative indicators, a comprehensive evaluation model for the reliability of ventilation systems in underground metal mines was established based on the coupling of binary connection numbers and projection grey target decision-making theory. Firstly, considering the actual situation of ventilation system engineering, 24 important influencing factors were selected from five aspects: ventilation system environment, ventilation facility status, ventilation safety management status, ventilation prevention and disaster relief system construction, and overall employee quality. A multi-level comprehensive evaluation index system for the reliability of underground metal mine ventilation system was constructed; Secondly, the order relationship analysis method is applied to determine the subjective weights of indicators in a hierarchical manner. The binary connection number theory is used to unify the mixed indicator data, and the projection consistency coefficient of the evaluated object is calculated based on the projection grey target decision theory. The advantages and disadvantages of the evaluated object are comprehensively analyzed and compared; Finally, based on the research background of three underground metal mines, relevant calculations were conducted to determine the reliability status of the ventilation systems of the three mines, and the evaluation results were compared with the fuzzy comprehensive analysis method and cloud model evaluation models. The research results indicate that the reliability ranking of the ventilation systems in three mines is K2>K1>K3, and the evaluation results of the three evaluation models are identical and consistent with the actual mining engineering. This verifies the effectiveness of the proposed method based on binary connection numbers and projection grey target decision-making theory in the reliability evaluation of underground metal mine ventilation systems, and can provide new ideas for evaluation work.
- 1
Experimental study on enhanced flotation of low rank coal with difficult-float and difficult-selectAbstract:
An experimental study was conducted at the Shigetai coal preparation plant to address the challenges of flotation and separation of low rank coal slime. The results showed that the content of particles ranging from 1.6-1.8 g/cm3 in coal slime is high. The coal-mineral intergrowth particles make it difficult to efficiently separate them. Diesel is difficult to improve the floatability of low-rank coal due to the hydrophilic coal surface. However, the synergistic adsorption of diesel and sodium oleate could improve the floatability of low rank coal. Sodium hexametaphosphate could enhance the electrostatic repulsion between gangue and coal particles, and it could decrease the number of fine gangue particles coating on the clean coal surface. Grinding was used to promote the separation of coal and gangue to the dissociation of coal and gangue. Finally, using a combination of 500 g/t sodium oleate, 4000 g/t diesel and 500 g/t sodium hexametaphosphate as the flotation reagents for the interface chemical regulation, the flotation of low rank coal with difficult floatable and difficult separate was enhanced. The timed-release results showed that the yield of clean coal could reach 56.69% when the required ash content of clean coal is 10%, and the flotation selectivity index could increase by 3.54. It was concluded that the combination of grinding and a reagent combination of diesel-sodium oleate-sodium hexametaphosphate could significantly improve the flotation separation efficiency of low rank coal slime with difficult floatable and difficult separate.
- 1
Fine Modeling And Virtual Reality Rlatform Construction of Shuangyang Coal Mine Based on Multi-Source Data FusionAbstract:
Aiming at the current situation of the low mining height of extremely thin coal seam working face, difficulty in equipment selection and low working safety factor, combined with the backward problem of intelligent mining technology in Shuangyang coal mine, we improves the efficiency of thin coal mining and reduces production safety risks by establishing a multi-source data-driven refined geological model and a virtual reality platform.Firstly, on the basis of acquiring multi-source heterogeneous data of mines such as borehole and 3D seismic, we analyzed and classified them. Then based on DTM model, path cutting algorithm, distance weighted interpolation and other means, a comprehensive geological model of extremely thin coal seam was established, which integrated roadway, fault, mining area, coal and rock stratum and working face. Finally, we built a virtual reality cloud platform, combined Unity3D development engine and WebGL technology to render and release the constructed 3D visualization model, and carried out the monitoring arrangement of environment perception, ventilation, ground pressure and other data in the refined model. At the same time, in order to take into account the convenience of acquiring underground construction data, the uni-app framework was used to develop the mobile platform, which enhanced the timeliness of information management. The results indicate that the refined modeling and visualization platform application method of very thin coal seam proposed in this study is of practical significance to improve the transparency of working face, mining intelligence, digitalization of risk warning and informationization of production management.
- 1
Open Pit Mine based on Truck Exhaust Emission Factors Dust Mass Concentration PredictionAbstract:
The accurate prediction of open-pit mine dust pollution, which is harmful to the ecological environment of the mining area and the health of the employees, is an important guide for air pollution prevention and control. In this study, a dust concentration prediction model based on Gray Wolf Algorithm Optimized Random Forest (GWO-RF) is proposed. The model adds truck exhaust emission factors in mining areas to the characteristic variables and calculates the content of particulate pollutants in truck exhaust. According to the results of the study, it was shown that the noise reduction of the dust mass concentration using the moving average method effectively improved the prediction effect; and the fitting ability and the highest accuracy of prediction of the GWO-RF were further verified by comparing with other traditional models.
- 1
Experimental study on the characteristics of all tailings filling materials in a spodumene mine in western SichuanAbstract:
In order to explore the feasibility of using all tailing as filling material in a spodumene mine in western Sichuan, the experimental study on the characteristics of all tailing tailing filling material was carried out. The results show that 83376 anionic flocculant has the best flocculating in the static flocculating. The optimal addition amount is 20g/t and the optimal initial slurry mass concentration is 12%. According to the dynamic flocculation experiment, it is recommended that the solid load of all tailings is 0.46 t/m2?h, and the dense underflow concentration of all tailings can reach 68.78% and the solid content of overflow water is 127.3ppm under this condition. The strength of the all-tailing cemented backfill is proportional to the mass concentration and the ratio of lime to sand. According to the strength requirements of the backfill in the mining method and combined with the experimental results of filling ratio strength, the ratio of filling slurry in the first step of the stope is recommended to be 68% mass concentration and lime to sand ratio 1: 3 (R28= 3.16MPa), and the two-step filling slurry ratio parameters are recommended as mass concentration 68%, lime sand ratio 1:10 (R28=0.62MPa).
- 1
Research on safety application of lithium-ion battery power supply in non-coal underground minesAbstract:
Lithium-ion battery power supply is an important development direction of non-coal mine underground mining equipment. According to the use characteristics and safety requirements of mine lithium-ion battery power supply, the mechanical structure, thermal effect control, electrical characteristics, battery management system, electromagnetic compatibility and other safety technologies are studied. The technical requirements and verification methods are put forward respectively, and the following conclusions are drawn : the shell and pressure relief valve of the power supply should reach the IP54 protection level ; the power supply should be equipped with a thermal management system and a reasonable free space should be designed internally. The single cell should be connected in series to ensure the consistency of its internal resistance, capacity and voltage. The battery management system should have the real-time monitoring and protection function of single battery and power supply. The electromagnetic radiation and conduction emission energy of the power supply are controlled at three level , and it has the anti-interference ability of radiation, conduction, electric fast transient pulse group and electrostatic discharge. The practical application shows that the lithium-ion battery power supply can be used for mine underground transportation vehicles after special safety design and verification, which can replace diesel-powered vehicles and help non-coal underground mines to achieve green and low-carbon mining.
- 1
Study on the influencing factors of composite roof end face roof caving based on UDECAbstract:
In view of the fact that the end face of large buried composite roof is prone to roof fall and the coal wall is prone to spalling, with the 7242 working face of Suntuan coal mine as background. The influence law of composite roof end face caving is studied from the aspects of end face distance support working resistance, roof cohesion. Using theoretical calculation, numerical simulation method. The results show that the end face distance is the main factor affecting the end face caving. The decrease of the end face distance can reduce the development of roof cracks and improve the stability of the end face roof. The working resistance of the support indirectly affects the stability of the end face roof. The working resistance of the support is negatively correlated with the crack development height of the roof and the occurrence of roof fall accidents. The rock mass with larger cohesion has a positive effect on improving the stability of the end face roof. The stability control measures of the end face roof of 7242 working face are put forward and implemented on site, which ensures the stability of the end face roof. The research results are conducive to promoting the innovation and development of the prevention and control technology of composite roof end face caving.
- 1
Optimization of floor grouting reinforcement depth based on elastic modulus of composite rock massAbstract:
Based on the background of coal seam floor grouting reinforcement project in Jiaozuo mining area, the change of elastic modulus of rock mass before and after floor grouting is measured by ultrasonic method, the characteristics of the overall strength of composite rock strata within the range of grouting depth are obtained quantitatively, and the influence of floor grouting reinforcement on the failure zone of composite rock floor is analyzed. The research shows that the elastic modulus increases respectively after grouting reinforcement (Mudstone increases by 640%~852%, sandy mudstone increases by 241%~641%, sandstone increases by 221%~247%, L9 limestone increases by 176% and L8 limestone increases by 40%~159%), and the failure depth of floor decreases by about 62%, which is from 30.59m to 11.7m. As the failure depth of the floor decreases after grouting reinforcement, the thickness of the absolute waterproof layer increases. The absolute waterproof layer thickness of floor is obtained according to the characteristics of rock strength variation, and the grouting depth of floor is optimized. The double-layer layout of grouting drill holes is adopted to ensure the grouting effect and reduce the total quantities of 3140m drilling depth, saving 35 days of construction period compared with the original plan.
- 1
Industrial Experimental Study on Fiber Optic Sensing of Pressure Relief Effect in Coal and Rock Mining with Upper Urotective LayerAbstract:
Clarifying the pressure relief space effect of protective layer mining is crucial for optimizing the layout of mine development. Taking Cucurbitacin Coal Mine as the engineering background, the industrial test method of monitoring the deformation of coal and rock mass with distributed optical fiber sensing technology is adopted. According to the spatial position relationship of working face mining and the change state of light sensing data, the dynamic change characteristics of the strain distribution of underlying coal and rock mass are analyzed, and the dynamic change process of stress increase, stress decrease, and stress recovery experienced by the underlying coal and rock mass during the mining of the upper protective layer is obtained, The significant differences in the scale of strain increase and decrease in coal and rock masses under different depth conditions were revealed, and the parameters of the relief protection range for upper protective layer mining were obtained: the relief angles of dip and strike were 63.6 ° and 58.7 °, respectively, and the relief lag distance and maximum depth were 14.2 m and 28.4 m, respectively. The research results can provide important reference for the promotion and application of distributed fiber optic sensing technology in monitoring the pressure relief effect of protective layer mining.
- 1
Experimental study on separation of complex refractory iron oxide ore in JingtieshanAbstract:
Abstract:For many years, the ore utilization rate of V ore body in Huashugou mining area of Jingtieshan has been low. In order to display output capacity of V ore body adequately and ensure the balance of mining relationship between various ore bodies in the mining area, the experimental study on the process conditions of pre-concentration of lump ore-shaft furnace roasting-magnetic separation-reverse flotation was carried out for the complex refractory V ore body iron oxide ore. This raw ore contains the grade of TFe was 25.92%, the main minerals hematite ( specularite ), limonite and siderite were finely disseminated, and the grade of gangue mineral SiO2 was as high as 40.10%. After 13.33% of the raw ore was pre-selected and discarded, the reduction roasting was carried out at a reducing agent mass ratio of 4% at a temperature of 650 ℃ for 45 minutes to 65 minutes. The magnetic separation concentrate was reground after two-stage grinding and three-stage magnetic separation. Then added the depressant caustic starch and the ameromine collector YG-328B before the reverse flotation of one roughing, one cleaning and four scavenging at room temperature was carried out. The grade of concentrate TFe grade iss 61.06%,the grade of SiO2 is 6.86%, and the recovery rate is 75.40%, which realizes the effective recovery of the ore resources of the V ore body.
- 1
Power coal price prediction based on LSTM modelAbstract:
Coal is an important basic energy, especially thermal coal occupies a very high strategic position in China, but the prediction of coal price is very difficult. In order to use intelligent algorithm to predict the price of thermal coal, the recurrent neural network ( RRN ) is introduced. On this basis, according to the characteristics of the fluctuation of thermal coal price over time, the RNN model is optimized to establish the long-term and short-term memory model ( LSTM ). At the same time, the support vector regression machine model ( SVR ) is introduced, and it is connected in series with LSTM to form the LSTM-SVR combination model, so as to reduce the risk of selecting a single model for prediction and improve the accuracy of prediction results. In order to improve the correlation between the characteristic data and the price of thermal coal, the data smoothing algorithm is introduced. Finally, it is concluded that the development trend of thermal coal price predicted by LSTM-SVR model has a high linear fitting with the actual price, and the predicted results are very close to the real coal price in value.
- 1
Research and application of overall dynamic optimization of metal mine technical indicators based on IDE algorithmAbstract:
In order to make better use of metal mineral resources, the overall dynamic optimization study of mine technology indexes is carried out. Firstly, the kernel density estimation method, BP neural network and exponential regression method are used to fit the relational model of technical indicators respectively; then, based on this, the overall dynamic optimization model is constructed and the corresponding improved differential evolution (IDE) algorithm is proposed; finally, the established relational model, optimization model and algorithm are applied to a large-scale Yinshan copper mine in China. The results show that: the established relational model fits well and has high application value; the optimization results are in line with the actual situation of the mine, verifying the validity of the model and algorithm, and it has guiding significance for mine production and planning.
- 1
Thermal stability characteristics of filling body under different temperature fieldsAbstract:
Due to the influence of geothermal energy, geographical location, terrain difference and climate environment, the thermal stability of cemented backfill changes. In order to reveal and master the performance evolution law of backfill under different temperature fields, the relationship between compressive strength of backfill and heating time under different temperature fields and between compressive strength of backfill and temperature field under different slurry temperatures was discussed through temperature curing and uniaxial compression tests. The results show that the strength of backfill decreases with the extension of curing time in each temperature field, that is, the curing time is negatively correlated with the compressive strength of backfill. The influence law and mechanism of mechanical strength and stability of backfill under different curing temperatures are studied and analyzed. The conclusion can provide theoretical support for tailings cemented backfill with different temperature differences.
- 1
Overburden Movement and Surface Settlement Law of Double Coal Column Working FaceAbstract:
Aiming at the structural problem of double coal column caused by shrinkage during the remining period of Hulusu coal mine, taking the working faces 21102 and 21201 of Hulusu coal mine as the engineering background, a comprehensive research method combining on-site measurement, similar simulation test and theoretical analysis was adopted, and the coal seam mining of the double coal column working face of the coal mine was used as an example. The results show that the No. 2-1 rock layer overlying the No. 2 rock layer is the main key layer, and the No. 2 and No. 3 hard rock layers form a masonry beam structure, which plays the most important control role in the occurrence of ore pressure and overburden movement in the stope. The surface monitoring data show that the 21102 working face has completely entered the stable period of mining subsidence, and when the 21201 working face is mined, the surface sinking speed is timely and stable, and the overburden follows the mining, and there is no phenomenon that the overburden does not cross or sink and accumulates greater energy during the entire working face advancement process, which is less dangerous. Similar simulation test results show that with the excavation of the model, the transverse fracture gradually expands upward overlying layer, the separation distance also gradually expands, and the unstable collapse occurs, the fault angle of the overburden on the left side of the 21102 working face is 58°, the fault angle of the overburden on the right side is 62°, the fault angle of the overburden on the left side of the 21201 working face is 56°, and the fault angle of the overburden on the right side is 59°. The research results can provide reference for the safe recovery of the working face of the deep buried double coal column.
- 1
Construction method and stability analysis of multi-source data fusion model for high and steep slopeAbstract:
Constructing a refined numerical calculation model that reflects the real geological body is the key to numerical simulation analysis. At present, the unity of three-dimensional geological modeling and three-dimensional numerical modeling needs to be improved. Therefore, it is of great significance to carry out research on the construction method of three-dimensional numerical model that reflects the real geological body. Based on the excellent three-dimensional geological model construction ability of 3DMine software, a numerical model modeling method of multi-software coupling ( 3DMine-Rhino-HyperMesh ) is proposed, which solves the problem of three-dimensional geological and numerical unified model construction of high and steep slope in open-pit mine. The specific steps and ideas of the modeling method are described in detail. Based on the engineering background of an open pit in Panzhihua, a refined numerical model reflecting the real geological body mining area is constructed, and the potential failure mechanism of the mine slope is analyzed. The results show that the model constructed by this modeling method has a good correspondence with the real geological body, and improves the grid quality of the numerical model, thus providing a new modeling idea for the numerical simulation calculation and analysis of large-scale complex geological bodies.
- 1
Research on safe recovery technology of first mining face over shallow buried deep thin coal areaAbstract:
In order to solve the problem that special geological conditions such as shallow depth of burial and thin coal seam are prone to cause safety accidents such as water collapse, sand collapse, crushing frame and roofing, the safety recovery technology of "bottom breaking and coal cutting" and "mining only but not releasing" is proposed with the background of special geological conditions and production method of Madi Liang coal mine. The core of the first mining working face over shallow depth of burial, thin coal area safe recovery technology, and in the working face mine pressure appeared and two lane overrun support pressure distribution and other aspects of the application effect analysis. The results show that the working face area cycle pressure presents significant "spatial phase", and the obvious pressure mainly appears in the central area. Compared with the shallow burial depth stage, the step and continuous distance of periodic pressure in the thin coal area and overlapping area increase, and the "local pressure" is obvious, but the pressure intensity is at a low level. During the period of shallow burial depth and thin coal zone, the tunnel surrounding rock convergence speed is slow and the deformation is small, the coal seam roof is not significantly separated, and the over-support pressure is not obvious, which effectively proves the reasonableness and reliability of this safe recovery technology.
- 1
2
Abstract:
Mining method optimization is a systematic project. Aiming at the problems such as subjective index weight and insufficient information utilization, a mining method optimization model based on game theory combination weighting and TOPSIS method is proposed based on a phosphate mine. The Rhino-Griddle method is adopted to establish a mining model. FLAC3D software is used to study the distribution rules of stope stress, displacement and plastic zone of different mining methods. Quantitative safety indicators are obtained, economic indicators and labor productivity indicators are introduced, and subjective and objective weights are determined by AHP method and CRITIC method respectively. Based on the game theory, the subjective and objective weights are optimized to get the comprehensive weights, and the forced progress of each scheme is calculated by TOPSIS method, and then the mining method suitable for a phosphate mine is optimized. The results show that the relative close degree of scheme l, scheme 2 and scheme 3 are 36.3%, 78.1% and 41.5% respectively. Scheme 2 is the optimal mining method, and the ore recovery rate is increased to 76.71%, the ore dilution rate is reduced by 5%, and the ore mining cost is reduced by 10.74 yuan/ton. The research results provide some reference value for domestic similar mining enterprises.
- 1
Study on Surface Subsidence Prediction under Repeated Mining in Karst Mountainous AreaAbstract:
In order to protect the surface ecological environment of the mining area and improve the prediction accuracy of surface subsidence deformation under repeated mining in karst mountainous areas. Firstly, the characteristics of overlying strata movement and surface landslide mechanism after coal seam mining were analyzed theoretically, and the influencing factors of surface movement and deformation in mountainous areas caused by coal seam mining were determined. On the basis of the original prediction model of the maximum surface subsidence value under repeated mining on the flat ground, considering the superposition effect of surface landslide on the maximum surface subsidence value, the prediction model of the maximum surface subsidence value under repeated mining in mountainous areas was constructed. Secondly,combined with the method of numerical simulation, the influence of coal seam mining on surface subsidence deformation under different ground slope was studied. Finally, the prediction model of maximum surface subsidence value under repeated mining in flat and mountainous areas was used to predict the surface subsidence deformation of goaf by probability integral method, and the prediction results were compared with the measured values. The results show that the prediction accuracy of the maximum surface subsidence value prediction model based on repeated mining in mountainous areas is 1.4 % higher than that of the original prediction model, and the prediction accuracy of the horizontal movement value is 4.3 % higher than that of the original prediction model. The applicability of the prediction model of the maximum surface subsidence value under repeated mining in mountainous areas can provide reference for the study of surface subsidence in similar mining areas.
- 1
Application of Consolidation-Cementation Technology in the Disposal of High Water Content Copper Tailings and its Economic ResearchAbstract:
Combined with the problem of high water content sludge disposal during the closure of Fengshan copper mine tailings reservoir, a treatment technology using drainage consolidation combined with cementation was proposed. The mud-water separation test under vacuum pressure was carried out by a developed model test device, and the results showed that the separating process of cement solidified tailings slurry under vacuum load was effectively improved. There was a significant decrease of water content after the treatment. The compactness improvement increased the frictional strength between tailings particles, and further improved the compressive strength of cement solidified tailings slurry. The mentioned technology can be used to the reduction and disposal utilization of tailings sludge with high water content as the result.Combined with the indoor test results of the project, there will be obvious differences in the economy of using different technologies to close the warehouse, and vacuum drainage consolidation can greatly reduce the cost.
- 1
Experimental Study on Pore Evolution of Red Sandstone under Freeze-thaw CyclesAbstract:
The freeze-thaw cycle will affect the pore structure of rocks in cold areas, which will lead to the failure of rock engineering. In this paper, the red sandstone samples with different freeze-thaw cycles (0, 20, 40) were observed by scanning electron microscopy observation (SEM), mercury injection capillary pressure tests (MICP) and low-temperature N2 gas adsorption (N2GA), and the pore evolution law of different scales (micro, transition, medium and large pores) was studied. The research results indicate that freeze-thaw cycles can alter the distribution pattern of pore size in red sandstone, leading to the continuous development and expansion of transition pores or mesopores from 50 to 680 nm to mesopores and macropores from 680 to 3800 nm. The freeze-thaw cycle is beneficial for the development and generation of micropores or transitional pores smaller than 50 nm in red sandstone, and has the greatest impact on micropores at 3-4 nm. The research results can lay a foundation for revealing the mechanism of rock freeze-thaw, and provide theoretical guidance for resource development, engineering construction, and safety construction in cold areas.
- 1
YANG Dengfeng1,LI Xiaoshuang2,MA Tiahui3,XIE Shengrong4(1. College of Science, Qingdao University of Technology,Qingdao Shandong 266033,China；Abstract:
When a shallow-buried coal seam working face is advanced to the upper slope section of a valley terrain, it is easy to occur that the key layer broken blocks slide and lose stability along the coal wall, causing a large range of dynamic rock pressure disasters to occur in the working face. Based on the fracture characteristics of the roof in the uphill section of the valley, a mechanical model is constructed based on the fracture mechanics analysis method, and the mechanical mechanism of roof instability and the basic roof fracture instability conditions are discussed. The calculation formulas for the roof weighting step and the working resistance of the support are obtained, and the key disaster causing factors are analyzed. The research results show that the concentrated stress and stress intensity factor at the crack tip of the basic top damage zone increase as the working face advances, and when the stress intensity factor increases to a critical value, the cantilever beam breaks the working face under pressure. The size of the valley slope angle has a major impact on the weighting step and the working resistance of the support. Factors such as the crack length in the damaged area, the basic top thickness, and fracture toughness also have a significant impact. Finally, the theoretical analysis results were verified by an on-site monitoring example of 2103 working face in Madiliang Coal Mine, and on this basis, the reasonable value of support resistance was further analyzed. The above research conclusions provide a new method for studying the mechanism of roof instability and the relationship between surrounding rock supports in the uphill section of a working face that passes through valleys, improving the accuracy of roof control, and effectively promoting the safe production of the mine.
- 1
Intelligent Identification of Miners" Safety Wear in Dark Environment in Coal Mine Based on Improved YOLOv5Abstract:
Intelligent recognition of miners' safety in underground coal mines is one of the important protection measures to prevent miners from accidental injuries, and it is crucial to improve the recognition accuracy in dark environments such as low light in underground coal mines. A target detection algorithm based on enhanced YOLOv5 is proposed for intelligent recognition of miners' safety wear. Firstly, the data is collected in the field to build the safety wear dataset, and then it is input into the low light enhancement network Zero-DCE, which in turn improves the generalization ability of the model; secondly, the C-ASPP module is proposed, and by optimizing the ASPP and adding the attention mechanism, it is added into the backbone network to make the model focus on the features of the safety wear area more efficiently; Then, the backbone is incorporated into the Transformer algorithm is incorporated into the backbone to enhance the dynamic adjustment capability of the model to different scale targets; finally, in the feature fusion stage, a bidirectional feature fusion pyramid model is used to improve the feature extraction capability and detection performance of the model. The test results show that the improved algorithm, with an average detection accuracy of 90.2% and a detection speed of 81.2 frames/s, has higher accuracy and speed compared with other algorithms, and can meet miners' safe wear identification requirements in underground working areas.
- 1
Stope length optimization and engineering application of stage open stope with subsequent filling methodAbstract:
The stage open stope with subsequent filling mining method is mainly applicable to medium and large thick ore bodies, which is widely used in metal mines. It has the advantages of high production efficiency, high economic benefit and safety in production and operation. For mining method design, the selection of stope parameters is the key point of mining method. The length of stope is very important to the actual production. Reasonable stope length plays an important role in improving the safety and productivity of mine personnel. In this paper, FLAC3D is used to analyze the changes of stress, displacement and plastic failure zone of roof panel and side wall of mine under different excavation steps, to analyze the influence of different excavation steps on the stability of mine house, and to optimize the structural parameters of stope. FLAC3D is used to simulate the excavation model of the ore body, and a comprehensive analysis is made from five angles: roof vertical displacement and stress, side horizontal displacement and stress, and plastic zone distribution. The study shows that when the roadway is not supported, the maximum tensile stress of the roof is close to the tensile strength of the area, and the maximum tensile stress of the side is close to the tensile strength of the ore in the area, and the plastic zone of the roof tensile shear failure gradually increases, and there is a trend of penetration. At this time, both the roof and the side of the stope gradually lose stability. Therefore, considering the economic benefits and the roadway without support, the stope length is 36m, which is the optimal stope length. It can effectively ensure the production capacity and stability of stope.
- 1
Study on the Optimization of Zoning Mining Plan for Deep Orebody in Chengchao Iron MineAbstract:
The mining of the -500m middle section ore body at Chengchao Iron Mine is coming to an end and is about to enter the stage of mining the -570m middle section ore body. Only mining the -570m middle section ore body cannot guarantee production demand. In order to ensure the production capacity demand, Chengchao Iron Mine also conducts mining on the -570m and -675m middle sections. This article takes the -570m and -675m middle sections of Chengchao Iron Mine and the surrounding rock as the research objects, studies the impact of different mining schemes on surface stability, and establishes a three-dimensional numerical model using MIDAS software, the three-dimensional finite difference software FLAC3D is used to simulate and analyze the ground strata movement caused by the completion of underground mining under different mining schemes. Based on the numerical simulation results, the vertical ground subsidence at each stage under different schemes is compared, and then the stope stress distribution of the scheme is analyzed and stability suggestions are proposed. The results show that after the deep mining of the Chengchao Iron Mine, the main impact of deep mining on the surface is directly above the ore body, and the size of surface subsidence is inversely proportional to the distance from the collapse pit. The mining plan for the middle section of -570m and -675m can achieve a dynamic balance between surface stability and economic benefits.
- 1
The Screening of Reconstructed Soil based on Entropy EWM-VIKOR MethodAbstract:
Land reclamation is crucial to vegetation restoration with mining area, and soil reconstruction can effectively solve the problem of scarce topsoil resources. In this study, Coal Gangue Ecological Aggregate and Topsoil were mixed in different proportions to form five treatments. Through the determination of pH, Organic Matter content, Total Nitrogen content, Available Phosphorus content and Readily Available Potassium content, the influence of Coal Gangue Ecological Aggregate ratio on the nutrient index of each treatment was analyzed, and the optimal ratio of Coal Gangue Ecological Aggregate and Topsoil was selected based on the Entropy Right Method and Vlsekrijumska Optimizacija I Kompromisno Resenje method. In order to solve the problems of poor soil, scarce topsoil, and difficult land reclamation in the mining area. The results show that:（1）with the increase of the proportion of Coal Gangue Ecological Aggregate, the pH of different ratios is gradually decreased, and the pH between treatments has significant differences.（2）The proportion of Coal Gangue Ecological Aggregate has a significant impact on Organic Matter content, Total Nitrogen content and Readily Available Potassium content, and has no significant impact on Available Phosphorus content. In addition, with the increase of the proportion of Coal Gangue Ecological Aggregate, Organic Matter content, Total Nitrogen content and Readily Available Potassium content treated with different ratios showed a downward trend, while Available Phosphorus content showed a trend of rising first and then decreasing.（3）The entropy Entropy Weight Method and Vlsekrijumska Optimizacija I Kompromisno Resenje method is used to calculate the minimum Q value of X2 treatment, with the optimal ratio of 30% Coal Gangue Ecological Aggregate and 70% Topsoil.
- 1
Distribution of Mining Fractures and Porosity of Overlying Oil Shale in Coal Mine StopeAbstract:
In order to study the evolution mechanism of overlying mining fractures during the advancement of overlying shale face, taking Nanjiatsui Coal Mine in Zichang County as the engineering background, UDEC simulation software was used to analyze the overburden collapse characteristics and the dynamic evolution law of stress relief zone, and calculate the three-dimensional porosity distribution of the fully mined fallen rock mass according to the subsidence of the rock layer. The results show that the overburden collapse pattern of the stope shows a trapezoidal distribution with narrow upper and lower width, and the mining fracture shows a stable development on both sides of the goaf area, and the middle part is gradually compacted to the minimum value. The vertical stress in the pressure relief area was significantly lower than that in the middle of the goaf, and the oil shale layer was deposited in the collapse zone of the stope, and the distribution pattern of the pressure relief area gradually changed from "V" type to "W" type with the advancement of the working face. According to the three-dimensional porosity distribution model of the collapsed rock mass in the goaf area, it can be seen that the high porosity area in the same plane is distributed in a ring, and the ring area gradually shrinks to the middle of the goaf with the increase of rock layer occurrence height, and the whole is a "hollow ladder" structure.
- 1
A granular flow simulation study of temperature on the fracture extension pattern of deep fractured sandstoneAbstract:
In coal production, fractured sandstone is a rock with a porous and fractured structure. As the depth of coal mining increases, the temperature of the mine also gradually rises, which causes significant changes in the physical and mechanical properties of the sandstone, which in turn leads to increased crack expansion and damage phenomena. Therefore, the study of crack evolution in fractured sandstones under different temperature environments is of great significance for site safety production. This paper analyses the changes of crack evolution, damage mode, extension rate and extension pattern in fractured sandstone based on the particle flow method and simulated biaxial compression tests under different temperature conditions. The results show that, firstly, the crack expansion in the sandstone under different temperature conditions shows obvious differences, with the crack expansion rate being faster, the crack pattern showing a symmetrical "L" shape and the number of cracks being higher under high temperature conditions. Finally, the changes in friction and cohesion between grains in fractured sandstone under temperature conditions also affect the crack expansion. The above study provides a theoretical basis for an in-depth understanding of the mechanical properties of fractured sandstones and provides guidance for safe production in coal mines.
- 1
Experimental Study on Toothless Traction Machine for Mining ElevatorsAbstract:
Mining elevators are a new type of auxiliary lifting equipment that has emerged to adapt to large-scale mining. With the widespread use of metal and non-metallic mines, they have promoted their rapid development and have been included in the safety access directory management of mining products. They must undergo safety access tests before entering the mining field. The toothless traction machine for mining elevators is the core component of mining elevators, and its performance directly affects the safety performance and reliable operation of mining elevators.In response to the characteristics of low-speed and high torque of the toothless traction machine for mining elevators and the special requirements for starting, the test methods related to the load performance of the toothless traction machine were analyzed and studied, and a performance plan for the toothless traction machine for mining elevators was proposed. According to its characteristics, two loading methods have been proposed; Based on the mathematical model of the supporting permanent magnet synchronous motor, the technical requirements for the drive module were proposed, and the constructed loading test system was verified through experiments.
- 1
Prediction and Analysis of Surface Subsidence Range in the Open Pit to Underground Mine Area of Shilu Iron MineAbstract:
The study of surface subsidence range prediction is an important element in the safety management of open-pit to underground mines. To address the problem of surface subsidence in open-pit to underground mines, the Lanbscher method is applied to determine the angle and limit of collapse of each layer in the Beiyi mining area of Hainan Shilu iron ore mine, and FLAC numerical simulation experiment is used to obtain the characteristics of displacement field distribution in the mining area under different mining stages. Combining the interpolation grid method and the calculation of surface deformation tilt and horizontal deformation, the surface subsidence range of the Beiyi mining area under each mining stage level was circled, and the real-world model established by the UAV tilt photography technology revealed the surface subsidence type and spatial distribution, while the accuracy of the subsidence range was verified. Finally, targeted measures are proposed. It was found that: ①the Beiyi mining area is divided by E9, with the crumbling angle of the ore body ranging from 55° to 61° in the west and 67° to 73° in the east. ②Above the middle section of -180 m in the Beiyi mining area, the extent of the sinkhole and crumbling zone gradually increases as each middle section is mined in turn, mainly to the southeast, with the sinkhole increasing at a significantly faster rate than the crumbling zone; the crumbling zone stops developing after the ore body below the middle section of -180 m is mined. After the end of mining, the cave-in area mainly involves the bottom of the open pit and the western hill of Xiaoying Mountain on its east side, and the scope of the subsidence area includes the bottom of the open pit, the eastern part of the north and south gangs, the east gang and the whole hill of Xiaoying Mountain. ③At present, three types of surface subsidence phenomena, namely subsidence pits, surface cracks and landslides, are mainly found in the Beiyi mining area. In response to the surface collapse problem, measures such as closure of designated areas, backfilling of slopes with pressure feet, monitoring and early warning, and landslide stability analysis are proposed. The results of the study can provide a reference for similar mines in terms of subsidence range prediction and safety management.
- 1
Study on the Influence of Lateral Pressure Coefficient on Coal Seam Water Injection Drilling Based on FDM-DEMAbstract:
Coal seam water injection is widely used in coal mine shaft mining to moisten the coal body, make it weaker and less brittle, increase plasticity, and reduce the amount of floating dust generation. For deep low-permeability difficult-to-inject coal seams, the deformation and damage characteristics of the coal body around the coal seam injection holes affect the coal seam injection effect. Based on the finite difference method (FDM) and discrete element method (DEM), a fluid-solid coupling model is constructed to analyze the deformation and damage law of the coal body around the borehole and the seepage law of coal seam water injection under different lateral pressure coefficient conditions. The results show that the deformation and damage range around the borehole and the water injection pore water pressure are roughly distributed in a circular shape under the two-way isobaric conditions, while they are distributed in an elliptical shape under the two-way non-isobaric conditions, and the stress concentration phenomenon is more obvious in the smaller stress direction. As the lateral pressure coefficient increases within 1.6, the fracture area on both sides of the upper and lower sides of the borehole expands accordingly, but there is no significant difference in the fracture distribution area when the lateral pressure coefficient is 1.6, 1.8 and 2.0. The water pressure distribution and effective wetting range are similar to the distribution of the damage area. The vertical wetting range will change more with the increase of the lateral pressure coefficient, and the overall trend is increasing first and then changing less. In the lateral pressure coefficient between 1.0 and 1.6, the vertical wetting range is influenced by the lateral pressure coefficient. And then the stress concentration on both sides of the upper and lower sides increases, resulting in the local area of strong extrusion on both sides of the upper and lower sides, and the wetting range will not be significantly expanded. The research results can provide a reference basis for the design of water injection boreholes in deep low-permeability difficult-to-inject coal seams.
- 1
Study on The Optimal Development Planning of Western Mining Area Based on WEAP Water Resources ModelAbstract:
Water shortage seriously affects the sustainable development of coal mining in western mining areas. In order to guide the development planning of a mining area from the perspective of water resources so that the comprehensive benefits of the western mining area can be maximized, a mining area in the west is taken as an example, and a mine development plan is formulated according to the possible development direction of the mine area, considering four factors: population growth, mining scale, water conservation efforts, and greening intensity. Based on the simulation results, the multi-objective functions of economy, society and ecology of the mine area are established, and the optimal scenario is finally selected as a reference for the mine decision makers to make the next development plan. The results show that the plan with the highest overall benefit value is the "strong mining, strong water conservation and moderate greening" plan, with a comprehensive evaluation value of 0.6856. Using this plan as a reference for the next development plan of the mine, the carrying capacity of the mine"s water resources can be improved and the comprehensive development of the mine can be realized.
- 1
Research on overburden caving mechanism and cooperative treatment method in compound goafAbstract:
Aiming at the problem that compound goaf may lead to caving impact and surface collapse hazard in shallow hole retaining mining of a mine, the mechanism of overlying rock caving and the treatment method of goaf are studied by combining theoretical analysis and numerical simulation. Through the mechanical analysis of rock mass limit caving span, it is calculated that the limit caving span of goaf roof is 46.4m, which is less than the length of stope, and there is caving risk in goaf. The size of exposed space of goaf under the influence of mining-induced stress, the existence of dominant joint plane and stress-balanced arch are the main factors that lead to the fast and slow caving mechanism of overlying rock. For the condition of composite goaf, the remaining top column cannot effectively support the goaf, so it is urgent to control the goaf. Based on this, a compound goaf treatment method of synergistic filling of top pillar and surface in the middle stage of caving is proposed in this study. While eliminating the goaf hazards, 40% of the top pillar ore can be effectively recovered, generating economic benefits of 13.5 million yuan, and safe and efficient mining can be realized in mines with such conditions.
- 1
Design of JM Mine Undercutting Planning Based on Ore Caving LawAbstract:
The design of the direction and height of undercutting in block caving directly affects mine production and safety. This study is based on the background of the JM mining project in Serbia, and combines the undercutting height, the relationship between undercutting direction and principal stress, six undercutting planning were designed, and the different undercutting planning were analyzed from four aspects: the amount of ore rock caving, the area of initial caving undercutting, the area of continuous caving undercutting, and the velocity of ore rock caving, and favorable undercutting schemes are determined. The comprehensive analysis results show that the caving effect of the planning with the undercutting height of 10 m and the advancing direction perpendicular to the direction of the maximum principal stress is better. Under this plan, the initial caving undercutting area of the ore rock is between 4537.5 m2 and 5400 m2, the continuous caving undercutting area is between 16537.5 m2 and 18150 m2, and the continuous caving speed is 0.2599 m/d, which can meet the design production capacity.
- 1
Application Research on Panel Unlording Mining of Downward Drift Mining with Backfilling in Deep High-stress Broken DepositAbstract:
Aiming at the hazards of bottom drum,sidewall collapse and bulge when mining deep broken deposits under high stress conditions,the mining schema of downward large-size drift mining with backfilling based on panel unloading was designed. GOCAD software was used to establish a large-scale accurate orebody simulation model,which was converted into FLAC3D numerical model for calculation and analysis. The results show that the unloading effect of the panel unloading mining on the horizontal stress was obvious,and the two-step approach mining sequence was helpful to improve the unloading effect of the panel. The field test of unloading mining was selected in the 982 m level II panel of the mine,the stress change,rock stability and safety status of the approach in the mining process were analyzed by means of borehole stress monitoring,approach convergence monitoring and blasting vibration test,It was found that the horizontal stress of the approach in the panel area decreases greatly about 23% average after panel unloading,and the convergence of the approach was in a stable state. The mining efficiency of the large-section approach was improved by using the large cut-hole controlled blasting technology. The production capacity of unloading mining test panel was more than 1000 t/d,the dilution rate was 5.0%,the loss rate is 4.5%,the direct mining cost is 71±2 yuan/t,and good technical and economic indicators were obtained.
- 1
Digital Twin-Driven Remote Monitoring Technology of Self-Moving Belt Conveyor TailAbstract:
Aiming at the problems of complex and changing conditions, low intelligent level, poor moving quality and difficult condition monitoring in the process of self-moving belt conveyor tail movement in coal mine, the remote monitoring technology of self-moving belt conveyor tail in coal mine based on digital twin technology is studied. Firstly, by studying the application of the self-moving tail on the digital twin five-dimensional model, a general scheme of the self-moving tail digital twin monitoring system was proposed; Secondly, the attitude analysis of the equipment body and the forward-moving cylinder was carried out, and the motion simulation of the self-moving tail was realized in Unity3D; Finally, the virtual model of the self-moving tail and the remote control interface were established to realize the human-computer interaction and collaboration between the physical equipment and the virtual model. The experimental results show that the self-moving tail of the machine can move forward steadily driven by the constructed system based on digital twin technology, and the equipment motion state can be accurately presented in the virtual remote monitoring interface, and the virtual model of the equipment propulsion process and the motion data of the physical equipment can be collected, forming a 97.74% overlap between the virtual and real movement trajectories.
- 1
Research on the Development and Application of Optoelectronic Mineral Processing Method in Yunnan"s Medium and Low Grade Phosphate OresAbstract:
This article focuses on various types of "poor, fine, and miscellaneous" colloidal phosphate ores in Yunnan, and conducts experimental research on the application of optoelectronic beneficiation technology in the separation of colloidal phosphate ores using optoelectronic equipment. The experiment selected siliceous and silicate type, mixed type, and carbonate type medium and low grade phosphate rock for adaptability testing of photoelectric beneficiation. By analyzing the structural structure, mineral composition, usefulness, and gangue mineral composition of each type of phosphate rock, it provides a basis for photoelectric beneficiation research, determines the feasibility and sorting parameters of photoelectric beneficiation, and obtains the process parameters of photoelectric beneficiation for each type of phosphate rock, Optimize the technical parameters of photoelectric beneficiation detection and tracking recognition, and provide design basis for the construction of photoelectric beneficiation technology industrialization devices.
- 1
Research on the cumulative deformation effect of slope under cyclic blasting vibrationAbstract:
In order to study the cumulative dynamic load acting on the slope under cyclic blasting, blasting vibration data collection and cyclic simulation calculation were conducted on the eastern slope of the Jijiping mining site in Baima Iron Mine. By analyzing the on-site blasting vibration data, it is found that the vibration velocity of the slope in three directions first increases and then decreases, showing an overall downward trend, and the peak velocity is in the horizontal radial direction; Through FLAC3D software for cyclic loading calculation, as the number of explosions increases, the maximum horizontal displacement increases from 7.89mm to 8.05mm, and the corresponding shear strain increases from 7.44×10-4 to 7.88×10-4; The cumulative deformation of the slope is positively correlated with the number of blasting vibrations, and an expression is derived for the relationship between the horizontal displacement X and different blasting frequencies n, The calculation of the threshold of safe blasting frequency under production blasting intensity through numerical simulation method is of great significance for guiding mine safety production.
- 1
Research on time series prediction method of mine water inflow based on VMD-BiLSTM combined modelAbstract:
The accurate prediction of mine water inflow plays an important role in ensuring safe production and protecting the groundwater environment in coal mines. In order to improve the accuracy of time series prediction of mine water inflow, a combined prediction model of mine water inrush based on variational modal decomposition (VMD) and the optimization of bidirectional long short-term memory network (BiLSTM) by Bayesian algorithm is constructed. Firstly, VMD is used to decompose the time series data of mine water inflow into multiple subseries, and then the subseries obtained by decomposition are input into the BiLSTM model, and Bayesian algorithm is introduced to optimize the hyperparameters of each model, and finally the prediction results of each subseries are superimposed and summed to obtain the final predicted value. After comparing the prediction results with other models, it shows that the model has obvious advantages in single-step prediction, and its performance in multi-step prediction is also quite good, and the prediction accuracy can meet the production demand, and the effectiveness and applicability of the model in the timing prediction of mine water inflow are verified.
- 1
Study on damage evolution law and effective support of roadway surrounding rock under complex geological conditionsAbstract:
Mine roadway support has a positive effect on the stability of rock tunnels, but currently, roadway design is mainly based on experience, and there is a common phenomenon of roadway support design being too conservative or considering costs, resulting in a lack of support. This article equivalently interpolates the mining surrounding rock classification method into the geological strength index GSI, uses the Hoek Brown strength criterion and on-site geological survey data to determine the mechanical parameters of the surrounding rock, simulates the anchor mesh support structure based on on-site construction methods, quantifies the safety of the anchor mesh roadway support structure, establishes an empirical formula for evaluating the corresponding support effect, provides quantitative indicators for support safety evaluation, and verifies the feasibility of this method combined with on-site monitoring data. Research has shown that the spatial displacement of each point in the tunnel cross-section increases with the weakening of the surrounding rock mass, and the anchor mesh system has locally started to fail and fail when the surrounding rock grade is between 4 and 4.5; By determining the safety factor of anchor rods through the shear strength of materials, the support effect and structural safety can be effectively and quickly evaluated, thus achieving on-demand support design. The research results provide a convenient method for evaluating the support effect of anchor mesh tunnels with different levels of surrounding rock, which is convenient for on-site tunnel construction and design.
- 1
TOA Positioning Algorithm of Underground Moving Targets Based on UWB and Fingerprint LocationAbstract:
Aiming at the problems of low positioning accuracy and poor real-time performance caused by non line-of-sight propagation delay when positioning the underground personnel and equipment, this paper proposes a TOA positioning algorithm of underground moving targets based on UWB and fingerprint positioning. Firstly, the algorithm applies a two-way ranging (DS?TWR) method to measure the distance between the positioning base station and the positioning tag and then the Chan algorithm is constructed and the coordinates of the positioning tag are estimated; Secondly, Taylor algorithm is used to update the positioning results of Chan algorithm to suppress the NLOS delay error in mine tunnel; Finally, the optimal location estimation of the moving target is obtained by sequentially collecting distance fingerprints at specific points, estimating the horizontal and vertical coordinate errors of the moving target based on the improved AOA-LSSVM model, and compensating for the error with the Chan-Taylor algorithm. The experimental results show that the positioning accuracy of the proposed algorithm in static and dynamic ex-periments in the LOS (Line of Sight) environment has been improved by 18.6% and 64.7% respectively and that in the NLOS (Non Line of Sight) environment has been improved by 82.4% and 56.7% respectively compared to the Chan-Taylor algorithm, meeting the requirements for high-accuracy positioning of the underground target.
- 1
Study on Surrounding Rock Failure and Strata Movement Mechanism in Complex Goaf of Metal MineAbstract:
In order to elucidate the mechanism of surrounding rock failure and strata movement caused by complex mining goaf in metal mines, taking the east area of Jinshandian Iron Mine as an example, the engineering geology of the mining area was clarified, a large three-dimensional numerical model was established, and numerical calculations of underground mining were carried out. The calculated rock failure results are compared with the physical model test results to reveal the failure mechanism of the surrounding rock in the complex mining goaf and to propose an analysis index of discontinuous deformation of the failure angle based on the plastic failure of the rock mass. The results show that the variation law of failure angle analysis index with underground mining is relatively consistent with that of commonly used collapse angle. The failure angle of the hanging-wall remains approximately the same with the underground mining, the value is 40°~45°; the failure angle of the footwall decreases first with the mining and then stabilizes at 61°~62° after -500m level. The failure mechanism of the surrounding rocks revealed by numerical simulation and model test is consistent. The step-like fracture surface appears at the bottom of the rock layer of the hanging-wall, and obvious topping-sliding failure occurs, while the failure surface of the footwall surrounding rocks is steeply inclined, and the shear-sliding failure tracing the fault and structural surface occurs. The results of the study are an important guide to the safe production of underground mining in metal mines.
- 1
Study on Preparation and Pore Structure of Iron Tailings Sand Autoclaved Aerated Lightweight ConcreteAbstract:
In order to improve the macroscopic pore structure deterioration of autoclaved aerated lightweight concrete caused by the excessive admixture of iron tailings sand, the regulating effects of the content of gas-foaming agent (aluminum powder) and the mass ratio of gas-foaming agent and foam stabilizer (hydroxypropyl methylcellulose, HPMC) on the macroscopic pore structure of autoclaved iron tailings sand autoclaved aerated lightweight concrete and the effects on the compressive strength, bulk density and thermal conductivity of the specimens were studied. The results show that the iron tailings sand autoclaved aerated lightweight concrete has moderate compressive strength and bulk density at 0.09% of the mass ratio of gas-foaming agent and foam stabilizer of 1:5, which is close to the requirements of strength class of A2.5 and bulk density class of B05 as stipulated in the GB/T 11968-2020. On this basis, further increasing the content of foam stabilizer to the mass ratio of gas-foaming agent and foam stabilizer of 1:7 can effectively increase the proportion of tiny pores (pore area≤0.5 mm2), improve the uniformity of pores, reduce the rate of interconnection, so that the iron tailings sand autoclaved aerated lightweight concrete can withstand 5.19% higher pressure per unit volume density, and 6.8% lower thermal conductivity, with more excellent compressive and thermal insulation properties.
- 1
INFLUENCE OF DRIFT SPACING ON MECHANICAL BEHAVIOR AND DEFORMATION OF STOPE SURROUNDING ROCKAbstract:
Increasing the sublevel drift spacing of non- pillar sublevel caving method is beneficial to increase the ore amount of primary caving and improve the ore drawing effect. Based on the optimization scheme of the structural parameters of mining method in a certain mine, the stress distribution characteristics, displacement variation and plastic zone distribution law of the surrounding rock in stope are studied with the numerical simulation method under 5 possible drifts spacing, and the influence of drift spacing variation on the stability of the surrounding rock is analyzed. The results show that: (1) the maximum principal stress in the surrounding rock of roof and both sides of the drift show the characteristic that the greater the sublevel drift spacing is, the smaller the principal stress value is. However, the maximum principal stress changes with different depth of surrounding rock. (2) the minimum principal stress of the roof and the side wall rock increases first and then tends to be stable. The maximum principal stress is mainly distributed in the 4-10 m range of the side surrounding rock of the drift. The smaller the drift spacing, the mutual influence of the adjacent drifts causes stress superposition, which is easy to occur tension failure. (3) the displacement in the surrounding rock of drift roof and side wall presents a change rule of "large in the middle and small at both ends". After the drift excavation, the vertical displacement of the drift is manifested as the roof and the floor , and the horizontal displacement is manifested as the two-side wall convergence. Increasing the sublevel drift spacing has a great influence on the displacement distribution area and range of the roof surrounding rock, but it is beneficial to reduce the degree of mutual influence between adjacent drifts and maintain the overall stability of the drift surrounding rock. (4) the plastic zone of surrounding rock is mainly shear plastic zone, which is mainly distributed within 2 m around the drift, and the change of sublevel drift spacing has little influence on the expansion of the plastic zone.
- 1
Study on SurroundingRock Control Technology of Small Spacing and Large Section Roadway GroupAbstract:
In order to effectively control the surrounding rock deformation of small spacing and large section roadway in Panjiayao Mine, based on the theory of Protodyakonov, the theory of strong side and strong angle, and the theory of bolt suspension, the surrounding rock pressure at the lower part of the limit equilibrium arch and the additional equilibrium arch of the roadway is taken as the main control object. The formation of the limit equilibrium arch is inhibited by the support of the roadway side and corner, so as to reduce the surrounding rock pressure at the top and side of the roadway. According to the test results of geomechanical parameters of roadway surrounding rock in Panjiayao Mine, the formation process of Pu "s arch of roadway surrounding rock is analyzed, the curve equation of Pu "s arch is determined, the stress state of the top and side of the roadway is analyzed, and the roadway support parameters are calculated. The results show that the additional balanced arch span of the development roadway in Panjiayao Mine is 47.34 m and the height is 14.241 m. The maximum additional pressure of the additional balance arch is 99.886 KPa. The maximum pressure at the top and side of the roadway is located in the main transportation roadway, which is 198.608 KPa and 74.8343 KPa respectively. The roof and sides of the roadway are supported by bolts, and the corners and sides of the roadway are supported by anchor cables. Combined with the field test data, the overall deformation of the roadway is generally small, the bolt ( cable ) is stable and the change range is small, and the surrounding rock structure maintains good integrity.
- 1
Research on Machine Vision Image Enhancement Technology for Underground Coal MinesAbstract:
To address the problems of large local light and dark disparity, low contrast and loss of feature detail information in underground coal mine images, an improved homomorphic filtering algorithm is proposed for the enhancement of underground coal mine images. First, using an improved single-parameter homomorphic filtering algorithm to compress low frequencies and enhance high frequencies to improve image clarity; Transform the filtered image under HSV space and process the luminance component V using Contrast Limited Histogram Equalization (CLAHE); Finally, the HSV inversion is performed to obtain the image in RGB space to complete the image enhancement. The experimental results show that the algorithm effectively improves the effect of uneven illumination on images, enhances image sharpness and contrast, and improves the over-enhancement phenomenon of classical homomorphic filtering on images with large light-dark disparity while retaining the image feature detail information.
- 1
Similar Simulation Experiment on Drawing with flat-bottom structure by Mechanized Shrinkage Method for steeply inclined thin veinsAbstract:
In order to find out the ore flow law in narrow restricted space under different stope dip angle and inlet distance, the similarity experiment of mechanized ore drawing method of steep-dip extremely thin lode was carried out by using the similarity experiment model designed by ourselves. The experimental results show that the slope angle of moving funnel formed on the stope surface decreases with the stope layering up, which is more favorable for mechanized equipment to pass on the stope surface. When the stope angle is constant, the slope angle of the moving funnel formed on the surface of the ore pile increases with the increase of the distance between the drawing paths, and the amount of residual ore at the bottom of the stope increases with the increase of the distance between the drawing paths. When the distance between drawing paths is constant, the slope angle of moving funnel formed on the surface of ore heap decreases with the increase of stope angle, and the amount of residual ore at the bottom of stope decreases with the increase of drawing angle after a large amount of ore drawing. Through the drawing simulation experiment in narrow and long restricted space, taking the slope angle of the pit surface depression and the ore residual rate at the bottom as the evaluation indexes, the optimal distance between the ore drawing and the approach path meeting the mining process requirements of mechanized ore retaining method is determined to be 8m.
- 1
Trajectory measurement and straightness control method of fully mechanized mining faceAbstract:
Ensuring the straightness of the fully mechanized mining face is the foundation for achieving safe and efficient coal mining. Based on the geometric constraint relationship between the shearer, scraper conveyor, and hydraulic support, the straightness of the scraper conveyor is taken as a reflection of the straightness of the fully mechanized mining face, and then expressed through the operating trajectory of the shearer. In order to improve the calculation accuracy of the operating trajectory of the coal mining machine, the inertial navigation sensor and hydraulic support displacement sensor data are iteratively corrected and fused. Firstly, a longitudinal error model is established for the historical displacement sequence of a single hydraulic support, and a transverse error model is established for the primary displacement sequence of all hydraulic supports. Then, grey theory is used to eliminate errors and correct data for the two sequences. Then, the data from the inertial navigation sensor is used to obtain the trajectory of the shearer. The processed hydraulic support data is overlaid to form the support trajectory. Then, the idea of Kalman filter is used to iteratively update the trajectory of the shearer and the support to obtain the predicted trajectory. At the same time, the trajectory of the shearer and the predicted trajectory data are iteratively corrected. Simulation experiments show that this method can effectively compensate for the errors of inertial navigation sensors and hydraulic supports, and improve control accuracy.
- 1
Study on the classification of rock mass explosiveness and related unit consumption prediction in Pulang Copper MineAbstract:
To optimize the selection of blasting parameters for underground mining at Pulang Copper Mine, the rock masses in different areas are used as the basis. Adopting the theory and model of set pair analysis, the rock mass density with low linear correlation is easily obtained in engineeringρ、Tensile strength ft, compressive strength fc, rock integrity coefficient η to measure the indicators, the rock mass belonging to its eastern, western, and southern regions is classified for explosivity. Firstly, the single factor correlation degree of each rock sample is calculated, and the weight coefficient of each measurement condition is determined using the Analytic Hierarchy Process. Finally, a comprehensive expression based on these four indicators is obtained to reflect its explosiveness level. The research results show that the difficulty degree of its blastability is: the rock mass in the western region>the rock mass in the eastern region>the rock mass in the southern region. Based on the classification of explosivity, the prediction of explosive unit consumption was conducted for the eastern, southern, and western rock masses, providing certain guidance for the selection of blasting parameters.
- 1
Construction and application of 3d spatial flow field model of mine groundwaterAbstract:
With the continuous improvement of mine geological exploration in China, the geological exploration work is developing from shallow to deep. In the past long period of hydrogeological exploration work in mining areas, in view of the shallow mining depth, and in order to simplify the calculation, most of the groundwater movement is included in the two-dimensional plane flow category. With the continuous increase of the development scale, mining intensity and mining depth of mineral resources, the vertical movement characteristics of groundwater become more and more significant, especially under the condition of large drawdown, the groundwater flow field presents typical three-dimensional spatial flow field characteristics. If the vertical movement of groundwater is ignored and the three-dimensional model of groundwater flow system is simplified to a two-dimensional model, the model deviation will be large, resulting in serious distortion of the prediction results of mine water inflow. Therefore, The vertical velocity component of groundwater movement cannot be ignored. On the basis of conducting research on the construction of a three-dimensional spatial observation system for mining groundwater, this article constructs a three-dimensional flow field model for mining groundwater, proposes the theories of "sponge" and "mushroom" type groundwater systems, clarifies the movement laws, characteristics, key technologies for water prevention and control, and the principles of relevant technical systems The technical methods play a positive guiding role in hydrogeological exploration and water prevention and control work in mines of the same type, especially deep mining mines. Through practical application in Beiminghe Iron Mine and Sijiaying Iron Mine, we have deepened our understanding of the hydrogeological conditions in the mining area, greatly improved the prediction accuracy of mine pit water inflow, proposed suitable water prevention measures for the mine, and ensured mining safety.
- 1
Creep Model and Parameter Evolution Law of SandstoneAbstract:
It’s beneficial for a deeper understanding of the viscoelastic mechanical behavior of rocks that exploring the variation of creep model with loading time; For this purpose, based on fractional order theory, an improved Maxwell whose feasibility was verified by the creep test results of sandstone was established; Then, on this basis, A method is proposed to obtain the model parameters at different loading times; and the obtained results were fitted and sensitivity analyzed. It turns out, 1) The improved Maxwell model can characterize the viscoelastic properties of sandstone, and with the increase of stress, no significant change in fractional derivative, yet relaxation time is more sensitive to the stress than fractional order. 2) The fractional order is positively correlated with the development of cracks in rocks. when there are sufficient cracks in rocks, the fractional order is larger, and vice versa. 3) Essentially, the steady state creep stage of sandstone is the gradual transition from viscoelasticity to elastic-viscosity. 4) In fractional order evolution equations, coefficients a and b have a significant impact, with coefficient a mainly controlling the decay rate of fractional derivatives, while coefficient b reflects the way in which the fractional order decays.
- 1
Study on thickness optimization of horizontal isolating pillar in deep miningAbstract:
The second-stage mining of Baoling Iron Mine is completed, and the second-stage mining of deep ore body has been started. In order to avoid mutual interference between the upper/11 and lower mining areas and ensure the safety of mining, it is necessary to set up horizontal isolated pillars. By analyzing the mining status and engineering geological conditions of the mine, the thickness of the horizontal isolated pillars of the three schemes of 15m, 20m and 25m was preliminarily determined. The three-dimensional model was established by MidasGTS software, and the FLAC3D software was used to simulate the displacement, stress change and plastic damage of the safety pillars after the mining of the second-stage stope. The results show that the maximum displacements of the pillars in the three schemes are 5.57 cm, 5.48 cm and 5.38 cm, respectively. The maximum tensile stresses are 0.52 MPa, 0.43 MPa and 0.40 MPa, respectively. Scheme 1 produces a contiguous dense plastic element, and the local area of the pillar is penetrated by the plastic zone, and the pillar has undergone shear failure. The plastic zone of scheme 2 and scheme 3 is small, and only sporadic failure elements appear. As the thickness decreases, the displacement, stress and plastic zone in the pillar increase, and the stability of the pillar decreases. It is recommended to retain a horizontal isolated pillar of no less than 20 m. The research can provide experience for the design of isolated horizontal pillar under similar conditions.
- 1
Optimization of Mining Methods for Gently Inclined Thin Orebody Based on AHP-VWT-TOPSISAbstract:
A multi-attribute comprehensive decision model is constructed, which based on AHP-VWT-TOPSIS, to meet the requirements of scientific optimization of mining methods for gently inclined thin orebody. The variable weight theory(VWT) is used to avoid the "state imbalance" problem of the constant weight vector determined by the analytic hierarchy process(AHP) method, and then combined with technique for order preference by similarity to an ideal solution(TOPSIS) to obtain the superiority of each solution and select the optimal mining method. Taking a gold mine in Guizhou as an example, three suitable mining solutions were proposed, taking into account the actual mining situation. From the three levels of economy, technology and safety, 13 evaluation indexes were selected to construct a multi-attribute comprehensive decision matrix for mining method optimization. The comprehensive superior degrees of the three options is 21.32%, 49.13% and 58.02%, respectively, calculated by the established decision model, and it is decided to recommend the option three hydraulic pillar shield wall crumbling mining method. The optimization result is in line with the engineering reality, and the application effect shows that the comprehensive decision model has certain engineering application value for mining methods optimization.
- 1
Research on the Behavior Law and Prevention and Control Measures of Mining Pressure in Deep Coal Roadway Cutting and ReusingAbstract:
In order to improve the problem of large deformation of the roof and floor of the goaf retaining roadway, the 1462(1) track of Dingji Mine was taken as the research object. Through comprehensive numerical simulation and on-site measurement, the deformation law of the surrounding rock of the roadway was analyzed. It was found that as the distance between the advance working face increased, the vertical displacement of the surrounding rock of the roadway decreased to varying degrees. The deformation of the surrounding rock of the roadway from 60m to 120m ahead of the working face was within 20cm, and after 60m ahead of the working face, the impact of mining on the surrounding rock of the roadway was low, Gradually stabilizing, the influence range of the advanced support pressure on the working face after a mining operation is about 120m. By using the theoretical model of floor heave, it is calculated that the stress on the roadway floor varies with the change of stress concentration coefficient on both sides of the roadway; A scheme of using inverted bottom arch combined with roof support is proposed to control tunnel deformation. Through numerical simulation, it is found that this scheme can reduce the vertical displacement of the tunnel by 62.5%, which verifies the theoretical feasibility of this scheme. After on-site support, the effect of this scheme is good, and the displacement of the top and bottom plates decreases by 67%. The numerical simulation results are consistent with the on-site measurement, providing theoretical reference for the support of similar types of tunnels.
- 1
GRU Gas Concentration Prediction Model Based on Multi-scale Convolution and Attention MechanismAbstract:
The prediction of changes in gas concentration is of profound significance for preventing and controlling coal mine gas disasters and accidents. In order to improve the prediction accuracy of gas concentration by effectively extracting the multi-scale features of key information, this paper proposes a multi-scale convolution and attention mechanism gated recurrent unit neural network model ( MCA-GRU ). Firstly, the processed gas concentration data is subjected to a multi-scale convolution layer to extract the multi-scale features of the data. Secondly, the spatial attention module distributes the attention weight of the feature information to capture the important patterns and dynamic changes in the time series data. Finally, the correlation information of time series is fully extracted through the GRU layer. Therefore, this model can effectively obtain and focus on the important characteristics of gas concentration time series, thereby improving the prediction accuracy of gas concentration. This paper takes the gas monitoring data of a mine as a sample, and compares the model with the traditional CNN-LSTM model and CNN model. The results show that the MCA-GRU model overcomes the shortcomings of traditional prediction methods that cannot obtain multi-features and key information, and its overall prediction effect is better than CNN-LSTM and CNN models, especially when predicting peak-valley values. Due to the stronger generalization ability, the average absolute error and root mean square error of the MCA-GRU model are reduced by 14.3% and 20% respectively compared with the CNN-LSTM model, and R2 is increased by 4.5%. Therefore, the prediction model can make a certain contribution to the mine gas disaster.
- 1
Performance Characterization of Composite Dust Suppressor for Pyrite Dust in Open Pit Coal MineAbstract:
In order to effectively solve the problem of serious dust pollution caused by burning rock during mining and loading in open space of open-pit coal mines, a composite dust suppressor with functions of adhesion, moisture absorption, moisture retention, and wetting was developed using sodium carboxymethyl cellulose, magnesium chloride, citric acid, and sodium dodecylbenzene sulfonate as monomer materials. FT-IR and SEM were used to characterize the dust suppressant at the mesoscopic level, and its adhesion, water retention, evaporation resistance, wind erosion resistance, and dust suppression efficiency were measured experimentally. The performance of the dust suppressant was comprehensively analyzed. The results show that, under the premise of ensuring good fluidity, dust suppressants can effectively improve the hydrophilicity and adhesiveness of calcined rock dust, and can form a dense protective film on the dust surface; The water content of the dust sample sprayed with dust suppressant at 25 ℃ for 56h was 28%, and the water loss rate was slow; The results show that, under the premise of ensuring good fluidity, dust suppressants can effectively improve the hydrophilicity and adhesiveness of calcined rock dust, and can form a dense protective film on the dust surface; The water content of the dust sample sprayed with dust suppressant at 25 ℃ for 56h was 28%, and the water loss rate was slow; The evaporation capacity of the dust sample sprayed with dust suppressant at 55 ℃ is about 1/2 of that of the water dust sample, indicating that its anti evaporation performance is significant; Under different wind power levels, the wind erosion rate of dust samples sprayed with dust suppressant for 50 min is only 28; Comparative experiments on dust suppression efficiency show that the dust suppression efficiency of dust suppressants for total dust and respirable dust is 2.3 and 1.6 times higher than that of commercially available dust suppressants, respectively. Performance characterization studies have shown that independently developed composite dust suppressants can improve the physical and chemical properties of burned rock dust from the nature of rock materials, effectively control the precipitation of burned rock dust through chemical group modification, surface bonding, long-term moisturizing, and other functions, achieve dust source control during mining and loading, and provide scientific basis for comprehensive dust control in open-pit coal mines.
- 1
RQD Calibration Method Based on Core Recognition Intelligent Self-learningZHAO XingDong, 王宏宇, 王小兵, 王立君
Abstract:
RQD classification is an important means to analyze the engineering geological conditions of rock mass and evaluate the integrity of rock mass. At present, the traditional method of manually measuring and cataloging RQD has a large workload and low efficiency. Therefore, based on the Inception-v3 convolutional neural network model, this paper establishes a core-core box recognition model by performing feature extraction and transfer learning on a large number of core images taken in geological drilling, and realizes the recognition of cores with a length greater than 10 cm. Automatic identification and RQD acquisition, and then help to complete the drilling core catalog and rock mass quality evaluation. The application results of the Sanshandao Xiling mining area show that the difference between the calculation results of the model and the results obtained by the traditional manual method is only within 2%, which is convenient and fast and has high accuracy, which is suitable for application in actual mine engineering.
- 1
Target Detection Method of Truck in Open Pit Mine Based on Improved YOLOv3 AlgorithmAbstract:
As an excellent model in object detection algorithms, YOLOv3 has been widely used in many fields. An improved Yolov3 mining truck target detection algorithm is proposed in this paper to solve the problems of complex working environment and large variety of mining truck target scale. Three improvements are made on YOLOv3. First, add the fourth detection scale to the Darknet-53 backbone network of Yolov3, and the feature fusion is performed between the shallow network and the deep network to improve the small target detection effect. Second, use the K-means algorithm to improve the size of the prior bounding box and obtain the most suitable prior bounding box for mining trucks. Third, CIOU regression is used to optimize the loss function to improve the detection accuracy. The experimental results show that in the detection of mining trucks using the improved YOLOv3 model, the average detection accuracy (mAP) reaches 96.2%, which is 2.6% higher than the original YOLOv3 model, and the target detection speed can meet the needs of real-time detection.
- 1
Discrete Element Numerical Study on Strata Movement and Surface Deformation in the Iron Mine with Steeply Dipping DiscontinuitiesAbstract:
Taking the eastern area of Jinshandian Iron Mine as an example, a numerical study was conducted using discrete element software UDEC. The analysis was conducted from three aspects: rock failure, strata movement, and surface deformation, and combined with surface monitoring data to reveal the impact of steep dip structures on rock movement and surface deformation in metal mines. The research results indicate that as mining proceeds, the range of top collapse and tensile failure in the mining area continues to expand, and the plastic deformation and failure of the rock mass gradually intensify. The surface settlement displacement and horizontal displacement continuously increase with the downward excavation. At a mining level of -680m, the maximum surface settlement displacement is about 72.6m, and the maximum horizontal displacement is about 29.9m. Affected by the steep structural plane, the rock movement is divided into the toppling zone of the hanging wall, the collapse zone at the top of the goaf, and the shear slip zone of the footwall. The deformation and failure range of the hanging wall is significantly larger than that of the footwall. In the early stages of mining, the angle of movement and subsidence is relatively large. As mining deepens, the angle continuously decreases and eventually stabilizes. The calculation results can provide reference for other metal mines with steep dip structures.
- 1
Analysis of Loose Zone in Surrounding Rock of Deep Tunnel Based on Mogi-Coulomb CriterionAbstract:
The analysis of theSsurrounding rock loose zone is an important element in the field of coal mine support. Studying the calculation method of the radius of the loose zone and the influence of stress field and theSlithologic parameter on the radius of the loose zone is conducive to improving the safety factor of coal mine enterprises and economic production. Based onSMogi-Coulomb criterion, the calculation formula of the radius of the surrounding rock loose zone is derived, and compared with the Mohr-Coulomb criterion, Hoek-Brown criterion and unified strength theory. The applicability and advantages and disadvantages of the four criteria are analyzed and discussed. The results show that the Mogi-Coulomb criterion is beneficial to the economic production of coal mines, and the Hoek-Brown criterion is beneficial to the safe production of coal mines. The intermediate principal stress coefficient and cohesion have a significant effect on the radius of the loose zone. The influence of internal friction angle and cohesion, internal friction angle and intermediate principal stress coefficient on the radius of loose zone is limited. Increasing the intermediate principal stress coefficient within 0.5-1 and increasing the cohesion can effectively inhibit the expansion of the loose zone.
- 1
INFLUENCE OF CAVING DISTANCES ON STABILITY OF SURROUNDING ROCK OF MINING DRIFTAbstract:
In order to reveal the influence law of caving distances on the mechanical behavior, macroscopic deformation distribution characteristics and plastic zone distribution expansion characteristics of mining drift during mining with non-pillar sublevel caving method, the numerical simulation method is used to study the influence of five different caving distances on the stability of the surrounding rock of mining drift under the structural parameters of this mining method in a certain iron mine in Liaoning. The results show that (1) the surrounding rocks under different caving distances are all in compressive stress state, and the maximum and minimum principal stresses increase first and then decrease with the increase of distance from the end wall. The maximum principal stress reaches its maximum value at 2 m from the end wall, while the minimum principal stress reaches its maximum value at 4 ~ 5 m from the end wall. Increasing the caving step is beneficial to improve the stress state of surrounding rock. (2) after the ore caving with different caving distance, a "butterfly" displacement area is formed on both sides of the drift and at the spandrel, and a "subsidence" displacement area is formed at the top of the drift. With the increase of caving distance, the displacement of surrounding rock increases slightly, but the distribution characteristics of displacement are improved and the distribution range is narrowed. (3) after the caving, the plastic zone in the surrounding rock is mainly shear plastic zone, and the distribution range of tensile plastic zone is very small. With the increase of caving distance, the volume and increase of shear plastic zone are much larger than that of tensile plastic zone, and the surrounding rock is prone to shear failure.
- 1
Development Characteristics of Overburden Fracture in Protective Layer Mining Under High Gas Coal Seam ResearchAbstract:
The development height of fractured zone is the key factor to judge the mining feasibility of the lower protective layer. Taking No.8 coal and No.7 coal in Tongting Coal Mine as the engineering research background, the development characteristics of No.8 coal fractured zone after mining are analyzed by theoretical calculation, numerical simulation and distributed optical fiber observation method, and the mining feasibility is analyzed. The results show that: (1) Using the empirical formula of "three zones discrimination", it is calculated that coal No.7 is located at the lower edge of the fractured zone formed after coal No.8 mining, and theoretically it can be exploited in the lower protective layer. (2) Using UDEC to build a numerical model for the working face rock layer, it can be concluded that with the advance of the working face, the fracture zone will increase continuously. Under the action of overlying rock pressure, the working face will have a stable periodic pressure, and the cracks in the overlying rock layer will gradually develop to the high and deep rock layer. When the height of the fracture zone increases to a certain value, In some areas of the goaf, especially the caving zone and between the weak rock and the key layer, cracks will decrease, showing the phenomenon of "compaction", and the height of the fracture zone will decrease to a certain extent, and then tend to be stable. According to the model, the height of caving zone is 14.6m and fracture zone is 51.6m. It is highly consistent with the theoretical calculation, which further verifies the feasibility of mining the lower protective layer. (3) The distributed optical fiber measured strain data is processed, and combined with the actual mining situation of coal 8, the analysis shows that the fracture zone height is stable at 53.4m, which is highly consistent with the theoretical calculation and model simulation. Combined with the "three zones" formula calculation, numerical simulation and distributed optical fiber monitoring, the mutual verification results show that the development height of fractured zone after coal mining No.8 is about 50m, which is higher than the seam spacing between No.7 coal and No.8 coal, proving the feasibility of mining the lower protective layer in the actual project. At the same time, it can provide a reliable theoretical basis for the safety stoping of late mining area and working face.
- 1
Study on Stability of Inclined Layered Cemented Backfill in Downward DriftAbstract:
The Downward drift cemented filling mining method has been widely used in the green mining of metal mines in China. In this paper, the influence of different number of layering, layering angle, thickness of the cemented backfill and span height ratio of the goaf on the stability of the backfill roof was studied by FLAC 3D numerical simulation. The results show that the number of layering, the angle of layering and the span-height ratio of the goaf are positively correlated with the subsidence displacement of the backfill roof. In particular, when the span-height ratio increased to 1.75, the maximum displacement of backfill roof in 2 layers reached 24.56 cm. The thickness of the backfill and its subsidence displacement were negatively correlated. The maximum principal stress of the backfill roof exists in the form of compressive stress under different number of layering, and the more the number of layering, the greater the compressive stress. With the increase of the layering angle and the span height ratio of the goaf, the maximum main stress of the backfill roof gradually changes from compressive stress to tensile stress. Especially when the layering angle is 10°, the maximum tensile stress of the roof of the 2-layered backfill reaches 140 kPa. With the reduction of the thickness of the backfill roof, the concentration area of the compressive stress of the roof gradually changes from "semi-circular" to "saddle-shaped" with both ends raised and the middle depressed. The research results can provide reference for the design and application of backfill in downward drift filling mining.
- 1
Research on Optimization of Mining Plan Based on Improved Genetic AlgorithmAbstract:
In order to overcome the difficulty of finding an exact solution in the production plan of open-pit mines, this paper proposes a mining plan optimization method based on improved genetic algorithm. Firstly, the objective function is constructed by using technical and economic parameters such as ore recovery rate, waste rock mixing rate and mixed waste rock grade, and the model is constructed with annual mining volume and annual stripping volume as constraints; secondly, by adding catastrophe operator to the traditional The genetic algorithm is improved to prevent the algorithm from falling into premature maturity; finally, the performance of the proposed algorithm is verified by comparing the results of the algorithm. The results show that the proposed method can effectively deal with the mining planning problem of open-pit mines under constraints and find a mining planning scheme with a relative error of only about 2% in a short period of time. Compared with other methods, the proposed method is It has good advantages in parameter setting, model construction and running time.
- 1
Study on slope monitoring and early warning based on real-time dynamic global positioning measurementAbstract:
Under the influence of bad engineering geological conditions, slope sliding is easy to occur in Beishanxi mine of Shuguang Gold Copper Mine. In order to fully guarantee the safety of mine mining and prevent the slope landslide from causing major safety risks, Shuguang Gold and Copper Mine has established and improved the slope displacement real-time dynamic global positioning monitoring system according to the code requirements. Through data collection and analysis, a four-level monitoring and early warning system is established, the external key factors affecting slope stability are studied, and the movement law of slope slip zone in Beishanxi Mine is mastered. Finally, it provides important guarantee for mine safety production and can also provide reference basis for mines with similar conditions.
- 1
Study on Air Leakage Law of Goaf in Shallow and Thick Coal Seam MiningAbstract:
In order to study the law of air leakage in goaf of shallow and thick coal seam mining in wind-erosion landform mining area, taking 110501 working face of Yushuling mine as the engineering background, the phenomenon of air leakage in goaf was studied by combining similar simulation experiment, field measurement and numerical simulation. The research results show that: after 110501 working face mining, cracks develop to the surface, and the average spacing of surface air leakage cracks is about 15 m. In the vertical direction, the closer to the coal seam, the greater the subsidence displacement of overburden, and the maximum subsidence displacement is 8m. Under the condition that the fracture is connected to the surface, the range of the "three zones" of spontaneous combustion in the goaf increases, and the surface air flow is the main wind source. The air flow path is as follows: surface fissure - goaf - working face; The goaf 150m behind the working face is the main air leakage area, and the average air leakage intensity is 2.29 m3/s. The overlying rock cracks in the goaf are the main air leakage channel, and the cracks near the goaf return roadway have the strongest air leakage capacity. The research results can provide reference for determining the ventilation of working face and the danger area of spontaneous combustion in goaf during shallow and thick coal seam mining.
- 1
Research on the Reignition Characteristics and Key Functional Groups of Pre-Oxidized CoalAbstract:
In order to study the reignition characteristics of coal body and the change law of key functional groups in the closed fire zone, the long-flame coal from the comprehensive excavation face was collected, and the coal samples were treated with programmed heating at different atmospheres (nitrogen and dry air) and pre-oxidation temperatures (80°C, 120°C, 160°C and 220°C) with oxidation time of 4 h, and the raw coal was used as control to carry out TG-DTG and FTIR test analysis. The change patterns of three characteristic temperatures (T1, T2, T3) of coal samples were analyzed by TG-DTG, and the combustion performance of coal samples were analyzed by combining with the comprehensive combustion index formula. The changes of hydroxyl groups of coal samples under different atmospheres and pre-oxidation temperatures were analyzed by FTIR. The results showed that T1 and T3 of pre-oxidized coal were lower than that of raw coal and negatively correlated with pre-oxidation temperature, T2 increased and then decreased with pre-oxidation temperature and reached the peak at 120°C. The pre-oxidized coal was more prone to spontaneous combustion than raw coal, and the nitrogen atmosphere was safer than the dry air atmosphere. The maximum weight loss rate, Cb and S of pre-oxidized coal are higher than that of the original coal, and Hf is smaller than that of the original coal, and the oxidative combustion of coal is more stable after pre-oxidation. After pre-oxidation treatment with different atmospheres, the types of functional groups of coal samples did not change, but the hydroxyl content showed an ascending-descending changes. With the pre-oxidation temperature higher than 160°C, the fatty side chains in the coal reacted with oxygen to produce new hydroxyl groups, which made the hydroxyl content of dry-air atmosphere increase. The results of the study provide some guidance for the re-mining of the relic coal.
- 1
Optimization of electric shovel excavation time based on polynomial interpolationAbstract:
Aiming at the problems of low digging efficiency and unstable digging of the traditional mining shovel, the WK series mining shovel is used as the research object, and its digging trajectory is theoretically calculated, optimized and analyzed in the joint space of the shovel, and experimentally verified. Firstly, the D-H method is used to solve the forward and inverse kinematics of the shovel and select a reasonable digging trajectory; secondly, the segmented polynomial is used to interpolate the trajectory and select a suitable interpolation method for the mining shovel through comparative analysis; then, the combined optimization algorithm is used in Isight to optimize the trajectory with the shortest time for the segmented polynomial interpolation function; finally, by building the shovel experimental prototype Finally, the optimized trajectory is experimentally verified by building an experimental shovel prototype platform. The results show that the 4-3-3-3-4 segmented polynomial interpolation method is applicable to the optimal time trajectory planning of electric shovel, and the combined optimization algorithm improves the efficiency and accuracy of the optimization, and the digging efficiency of the optimized electric shovel can be improved by 18.5%, and the electric shovel experimental prototype can complete the digging task well within the optimized shortest time. The study provides a theoretical basis for the improvement of the excavation efficiency of the electric shovel.
- 1
The Effect of Flushing Water Pressure on Separation Performance of the Adjustable Combined CycloneAbstract:
In order to realize the cyclone classification with high efficiency and online control, a combined hydrocyclone was designed using the Cavex hydrocyclone as the structural prototype. The effect of flushing water pressure on the separation performance of the adjustable combined hydrocyclone was studied using a combination of computational fluid dynamics numerical simulation and experiments. The flow field inside the hydrocyclone was simulated by using Fluent software and RSM+VOF model. The pressure distribution and tangential velocity distribution of adjustable combined hydrocyclones under different flushing water pressures were compared and analyzed, and the movement trajectories of particles with different particle sizes were predicted by DPM model. The research results of classification experiments indicate that it is difficult to adjust the classification particle size of conventional hydrocyclone, and the Hancock comprehensive efficiency is the highest at 63.80% for the grading of -0.045 mm quartz particles. The adjustable combination cyclone reduces the bottom flow entrainment as the flushing water pressure increases, and the efficiency of this test can reach 79.58% for -0.045 mm quartz particles at a flushing water pressure of 0.02 MPa. The effect of flushing water pressure on the classification test of the adjustable combination cyclone was obtained in this study, which proves that the combination cyclone has obvious advantages over the conventional cyclone in terms of classification efficiency and adjustable control.
- 1
Research on Path Planning of Mine Vehicle Based on Adaptive Artificial Potential Field Model Predictive Control SystemAbstract:
It is of unique significance to realize autonomous path planning for mine vehicle to ensure operation safety, improve operation efficiency and improve working environment. Considering the unique terrain environment of mining area, the corresponding artificial potential field was constructed to evaluate the path, and combined with the model predictive control, the predictive ability of the planned path was improved. At the same time, different obstacles were distinguished, and fuzzy inference rules were used to allocate the weight of different obstacles according to the specific environment, so as to improve the adaptability to the special environment of mining area. Finally, a variety of driving scenarios were tested on the Carsim-Matlab co-simulation platform. The test results show that, compared with the comparison method, the proposed path planning method can implement path planning according to the emergency degree of collision in driving scenarios, thus improving the adaptability to the different driving environments of the mining area.
- 1
Study on Prediction of Surface Subsidence Coefficient Based on SSA-XGBoost ModelAbstract:
In order to solve the problems of limited accuracy, inconsistent model, complicated calculation and poor generalization of the current prediction model of surface subsidence coefficient, based on the analysis of the influencing factors of surface subsidence coefficient in the existing sample data, a prediction model based on sparrow search algorithm ( SSA ) optimized extreme gradient boosting tree ( XGBoost ) was established. The SSA-XGBoost model was used to iteratively learn the nonlinear mapping relationship between surface subsidence coefficient and coal seam mining height, coal seam dip angle, overburden lithology, deep mining ratio, base load ratio and base mining ratio, and the predicted subsidence coefficient based on SSA-XGBoost model was obtained. The accuracy of the predicted subsidence coefficient is analyzed by using the goodness of fit, the root mean square error of prediction and the average absolute percentage error. The results show that the goodness of fit of the combined model of surface subsidence coefficient prediction based on SSA-XGBoost model is 0.9516, the root mean square error of prediction is only 0.0206, and the average absolute percentage error is only 2.47 %. Compared with other models ( XGBoost model, BP neural network model and random forest algorithm model ), the goodness of fit increased by 15.79 %, 111 % and 101.10 % respectively, the root mean square error of prediction decreased by 1.59 %, 111 % and 6.75 % respectively, and the average absolute percentage error decreased by 1.59 %, 111 % and 6.75 % respectively. It can be seen that the prediction results of subsidence coefficient based on SSA-XGBoost have better fitting effect and higher model accuracy. The research results can provide reference for the prediction of surface subsidence coefficient.
- 1
Based on Alternating Excavation of Large Cross-section Cut Holes Research on Control of Surrounding Rock in TunnelsAbstract:
In order to study the problems of large subsidence, long construction period, and low efficiency of the secondary roadway roof caused by large cross-section cutting, the II8224 large cross-section cutting of Renlou Coal Mine is taken as the engineering background. In order to ensure the efficiency of cutting excavation and the safety of working face excavation, similar simulation, theoretical analysis, and on-site measurement research methods are used to analyze and compare the stress and displacement of the top and bottom of the surrounding rock. The research results indicate that during secondary excavation of large cross-section cut holes, secondary disturbances will occur, resulting in a rapid increase in anchor stress and a continuous increase in roof stress; The alternating excavation of large cross-section cut holes into a roadway avoids secondary wall expansion, reduces the support of one wall, and accelerates the construction process; The anchor belt, mesh and cable support method is adopted, and on-site data shows that the stress of the anchor rod and cable is controlled within a safe range. Under the condition of large cross-section cutting, the alternating excavation of a roadway effectively controls the deformation of the surrounding rock and solves the problem of difficulty in forming a roadway with a large span cross-section. The alternating excavation method improves the excavation efficiency, reduces engineering investment, increases safety, and provides useful reference for the construction of a roadway with a large cross-section cutting.
- 1
Experimental Study on Acoustic Emission and Characteristic Energy of Granite after High-temperature Thermal DamageAbstract:
In order to reveal the influence of high-temperature heating on the weakening mechanism of granite, the acoustic emission signal and energy variation law of characteristic points during uniaxial compression deformation of granite after heat treatment under 4 temperature gradients were studied by using rock uniaxial servo press and acoustic emission test system. The results show that the rigidity decreases and the plasticity increases of granite with the increase of temperature, the peak stress decreases rapidly at high temperatures, and the deformation increases at macroscopic failure; The change in acoustic emission signal correlates well with stress-strain curves. The percentage of acoustic emission counts at crack closure and initiation points is less affected by temperature, while the yield point acoustic emission activity is more affected by temperature; The total input energy and elastic energy at the crack closure point, cracking point, and yield point of granite are positively correlated with heating temperature, and the variation of dissipated energy at peak point reflects a critical temperature value between 500 ℃ and 600 ℃, which results in severe damage inside the rock. The research results can provide a theoretical reference for developing and using hot dry rock geothermal resources in China.
- 1
Bearing Capacity and Damage Failure Law of Anchor Grouting Reinforcement BodyAbstract:
In coal mining, the problem of high stress and severe disturbance has become increasingly prominent, resulting in varying degrees of fragmentation in the roadway. Anchor and grouting support is an important means to address the problem of broken surrounding rock. Therefore, exploring the bearing characteristics and failure features of anchor and grouting support specimen is of great significance for evaluating grouting effects and designing support strength. This study created grouted reinforcement specimens with different particle sizes and with and without anchors, and analyzed their failure characteristics, stress-strain curves, and acoustic emission signal features. The results show that the failure characteristics of the grouted reinforcement specimens after anchoring transitioned from tensile fracture to overall and regional peeling-off failure. Different particle size specimens also showed varying failure characteristics. The reinforcement effect of the anchor mainly manifests after the peak and increases the ductility and residual strength of the grouted reinforcement. The acoustic emission feature characterizes the fracture process of the anchor and grouting support specimen, with significant phase features. As the particle size increases, the duration of the active period of the acoustic emission increases, indicating a slower fracture process and more gradual release of energy.The experimental results provide a reference for the support design of surrounding rock with different crushing conditions in Fujiayan Coal Mine of Shanxi Lvliang.
- 1
Research on Unmanned Underground Vehicle Positioning Method Based on Visual Inertial FusionAbstract:
Synchronized Localization and Mapping (SLAM) technology is one of the key technologies for autonomous operation of mining underground vehicles in complex environments. This paper proposes a global positioning method based on the fusion of vision cameras and inertial sensors using the ORB-SLAM3 algorithm. The method simplifies the feature point management of the ORB-SLAM3 algorithm by adopting the MapPoint management mechanism, which further improves the accuracy of feature point matching. Experimental results show that the proposed method achieved an average improvement of 50.5%, 8.89%, and 77.46% over ORB-SLAM3 under three different modes in five public dataset sequences. In real-world tests conducted in mining underground, the method achieved higher global trajectory accuracy with only 0.4m global trajectory error in the optimal mode, indicating great potential for practical applications. Therefore, the proposed global positioning method based on the ORB-SLAM3 algorithm not only has better performance but also lower deployment costs.
- 1
Experimental Study on Creep Acoustic Emission Characteristics of Tailings Cemented Backfill under Three Point BendingAbstract:
In order to study the creep characteristics of cemented tailings backfill under three-point bending. The flexural strength of backfill with cement-sand ratio of 1:4,1:6 and 1:8 was measured by three-point bending test. On this basis, three-point bending creep acoustic emission test was carried out under graded loading. The creep and acoustic emission characteristics of cemented tailings backfill under different cement-sand ratios and load levels were studied. The results show that: (1) The whole creep process of tailings cemented backfill shows three creep stages of deceleration, steady state and acceleration under three-point bending. The tailings cemented filling body with cement-sand ratio of 1:4 and 1:6 enters the accelerated creep stage at the seventh load level, while the tailings cemented filling body with cement-sand ratio of 1:8 enters the accelerated creep stage at the fifth load level. (2) The instantaneous creep, final creep and final creep rate of the cemented tailings backfill increase with the increase of the load level. The larger the cement-sand ratio is, the stronger the creep ability of the filling body is, and the weaker the deformation ability is..(3) With the increase of load level, the acoustic emission hits, counts and energy all decrease first and then increase. The minimum values appear in the fourth level of cement-sand ratio of 1:4 and 1:6, but the minimum value appear in the third level of cement-sand ratio of 1:8 of the filling body. With the increase of cement-sand ratio, acoustic emission signals and energy generated during the fracture failure of the filling body and the accelerated creep stage show an increasing trend.
- 1
Analysis of Fracture Dilation and Damage of Freeze-thaw Limestone Under Uniaxial CompressionAbstract:
In order to study the evolution of fracture strain and progressive damage characteristic law under uniaxial compression of freeze-thaw limestone, 0, 10, 20 and 40 times freeze-thaw limestone uniaxial compression experiments were carried out, the freeze-thaw limestone damage constitutive equation based on fracture volume strain characteristics was established, the freeze-thaw limestone failure modes were explored with PFC2D numerical simulation software. The research shows that the uniaxial compressive strength, elastic modulus and Poisson"s ratio of freeze-thaw limestone decreased from 109.88 MPa, 65.38 GPa, and 0.225 to 70.36 MPa, 46.62 GPa, and 0.197. The maximum values of limestone fracture volume strain increased to 0.0106,0.0146,0.0269 after 10 times of freeze-thaw, 20 times of freeze-thaw and 40 times of freeze-thaw. Based on the volume strain inflection point method and the displacement regression analysis method, the freeze-thaw limestone dilation stresses decrease with the increase of the number of freeze-thaw cycles. And the relative error of the results obtained by the two methods is less than 10%. The theoretical stress-strain curve based on the fracture volume strain characteristics is in good agreement with the experimental curve, the theoretical damage constitutive equation is more applicable to low freeze-thaw cycles of limestone. The uniaxial compression failure modes of freeze-thaw limestone based on PFC2D are split mode and “split-shear” mode.
- 1
The Deformation Characteristics and Surrounding Rock Control of Mining while Digging Opposite RoadwayAbstract:
In view of the deformation and support problems caused by plastic zone expansion of surrounding rock at different stages in the process of underground mining and excavation, taking 23108 material roadway in inclined ditch Coal mine as the research object, the deformation characteristics and deformation causes of the plastic zone in the life cycle of the roadway were studied by means of theoretical analysis, numerical simulation and field measurement. The following conclusions are drawn: the roadway excavation approaches and enters the stage of superposition dynamic pressure (about 60m), the two sides of the roadway turn from symmetrical deformation to asymmetric deformation, and the plastic area of the roof and two sides significantly exceeds that of the floor, and dilatation occurs at 70m and 80m. When the roadway is driven to the stable goaf, the deformation of the two sides of the roadway gradually moves to the corner of the roof. In the process of tunneling and mining of working face, the surrounding rock of 23108 lane is not uniformly deteriorated and the stress distribution is locally concentrated. According to the numerical simulation analysis, the plastic failure is caused by the deviator stress of the roadway. Based on the dilatation and deformation of roadway, the original support scheme is improved. The field results show that the test results meet the production requirements.
- 1
Research on Excavation method and Size Optimization of Broken Ore in Metal Mine based on Two-dimensional FDEMAbstract:
The finite element and discrete element coupling method (FDEM) is used to establish two models with an approach size of 4.5m×4m. The deformation and failure process and stability of rock mass under mechanical excavation and blasting excavation are compared and analyzed, so as to determine the reasonable excavation method of broken ore body. Under the influence of horizontal stress and vertical stress, the influence of path span and height direction is different. The analysis models of the dimensions of 4m×4m, 4m×5m, 5m×5m, 6m×5m and 5m×6m were established respectively to simulate the deformation and stability of surrounding rock during mechanical excavation. According to the key point displacement catastrophe criterion and surrounding rock failure range catastrophe criterion, the final conclusions are as follows: When the mechanical excavation roadway size is no more than 5m×5m, the surrounding rock is relatively stable; When the size of mechanical excavation is larger than 5m×5m, the stability of surrounding rock is greatly reduced after mechanical excavation. The stability of surrounding rock is the lowest when the size of mechanical excavation approach is 5m×6m. The research process and results can provide reference for the mining of broken ore body by the route method, and guide the mine to carry out reasonable and efficient production.
- 1
Research on Coupling and Coordination Relationship between Mineral Resource Exploitation Efficiency and High-quality Economic DevelopmentAbstract:
Mineral resources exploitation and high-quality economic development affects and interacts with each other. In order to efficiently utilize mineral resources and promote high-quality economic development, evaluation index systems of mineral resources development and high-quality economic development were constructed, and the coupling coordination degree of mineral resources exploitation efficiency and high-quality economic development was analyzed from 2003 to 2021 by using data envelopment analysis method, entropy method and coupling coordination model. The results show that: the exploitation efficiency of mineral resources shows a fluctuating upward trend, while high-quality economic development shows a stable upward trend. The coupling level of the two has reached a high level of integration, and the coupling coordination degree has experienced the evolution process from dissonance to high-quality coordination, but has not achieved continuous synchronous development. The exploitation efficiency of mineral resources is ahead of the high-quality economic development. The exploitation of mineral resources provides solid material support and guarantee for the high-quality development of China"s economy. In order to promote the coordinated development of the two, it is necessary to rationally allocate mineral resources inputs to improve the exploitation efficiency of mineral resources, and improve the level of high-quality economic development through multiple channels.
- 1
Experimental Study On Effect Of Acidizing Time On Microstructure Of AnthraciteAbstract:
Acidizing time is crucial to the modification effect of coal seam. Taking Guizhou low permeability anthracite as the research object, using 6 % hydrofluoric acid as the modified main acid solution.The method of laboratory measurement and theoretical analysis was used to explore the evolution law of acidification time on functional groups and microcrystalline structure in coal, and the correlation between functional group content and microcrystalline structure of coal is analyzed. The results show that : 1 ) With the extension of acidification time, the relative content of aromatic structure and oxygen-containing functional groups of the experimental coal samples continued to increase, and there was a mutual transformation relationship between C-O and C=O stretching vibrations. 2 ) During the acidification process, the relative content of the aliphatic structure of the experimental coal sample has obvious time-dependent characteristics. The amplitude of this structural change is large when the acidification is 0 ~ 6 hours. After 9 ~ 12 hours of acidification, it tends to be stable. 3 ) The hydroxyl ether oxygen bond and hydroxyl π bond increase greatly, resulting in the hydroxyl content of coal samples after acidification for 3,6 and 9 hours is always higher than that of unacidified coal samples. 4 ) During the acidification process, the change of aromatic layer spacing of experimental coal samples is related to the change of aliphatic structure. The stacking height and ductility of coal samples under acidification are-6.13 % ~ 22.09 % and 36.66 % ~ 66.75 %, respectively. The research results provide a theoretical basis for the optimization of acidification modification time.
- 1
Discussion on the Reform Path of China"s Mineral Resources Regulatory System: Based on Factor Evaluation and International Experience AnalysisAbstract:
In order to implement the requirements of the Fourth Plenary Session of the 19th CPC Central Committee on "improving the natural resources supervision system", the article analyzes the connotation and basic scope of "mineral resources supervision". On the premise of analyzing the connotation and basic scope of "mineral resources supervision", the article evaluates the operation of China"s mineral resources supervision system based on the questionnaire survey results of mineral resources supervision in 23 provincial-level administrative regions and more than 1700 county-level administrative regions, and adopts the composition-driven factor method to evaluate the operation of China"s mineral resources supervision system. The proposed paths for the reform of China"s mineral resources regulatory system are put forward from different dimensions with reference to the experience of mineral resources regulation in western developed countries. The study concludes that (1) comprehensive policies, technical policies, and supporting policies as constituent factors, and systems, means, and organizations as driving factors collaborate to realize the full-cycle operation of China"s mineral resources regulatory system. (2) at present, China"s mineral resources regulation faces obstructive difficulties such as unclear regulatory matters, scattered means, unclear division of labor, and difficulties in matching regulatory tasks with personnel and funds. (3) developed countries such as the United States, Germany, Finland, and so on, have a mineral resources regulatory system with Finland and other developed countries" mineral resources regulatory systems are characterized by fine division of responsibilities, high public participation and full life-cycle coverage. (4) in the future work, the mineral resources regulatory system in the context of ecological civilization in the new era should be constructed from five dimensions: list, process, responsibility, capacity and support.
- 1
A k-mean Clustering Approach to the Identification of Rock Damage PrecursorsAbstract:
Rocks are prone to sudden damage under external disturbance, which is harmful to rock engineering, and it is important to study the precursors of rock damage. In this paper, we conducted uniaxial compression acoustic emission tests on red sandstone, and obtained three different types of acoustic emission signals by using five characteristic parameters of acoustic emission signals: energy, amplitude, rise time, duration and ringing count as feature vectors and performing k-means clustering analysis. The first and second types of acoustic emission signals appear continuously and intensively since the elastic stage until the end of the test, with no obvious evolutionary anomalies in the stage; the third type of signals appear sporadically in the elastic deformation stage and suddenly change to continuously and intensively in the deformation localization stage, with obvious evolutionary anomalies, which are consistent with the damage mechanism of rocks, and the abnormal time point is the same as the abrupt change time point of the scattered cloud map.
- 1
Carbon Performance Evaluation System and Application of Coal Enterprises and Their Production Mines from the Perspective of "Double Carbon"Abstract:
In view of the current situation that China lacks a quantifiable carbon performance evaluation system for coal enterprises and production mines from the perspective of "double carbon", the overall carbon performance evaluation index system of coal enterprises and the carbon performance evaluation index system of production mines were respectively constructed. The entropy weight-composite index evaluation model is used for evaluation. This system can not only evaluate the overall carbon performance of coal enterprises from the three dimensions of “economic development”, “carbon & pollution reduction”, “energy saving & comprehensive utilization”, but also evaluate the performance of each production mines through the three dimensions of “economic development”, “energy saving & consumption reduction”, and “emission & carbon reduction”. Select PingDingShan TianAn Coal Co.Ltd., which has relatively detailed disclosure of social responsibility reports, to conduct empirical analysis of carbon performance evaluation. The evaluation results show that the carbon performance evaluation index system constructed in this paper has a certain degree of scientificity and applicability, and can provide appropriate theoretical guidance for coal enterprises to find carbon emission reduction and carbon neutral paths.
- 1
Research on Surrounding Rock Stability Control Technology of Roadway before And after Roof Cutting in the Process of Heading Face MiningAbstract:
To solve the problems of serious deformation of the roadway surrounding rocks and difficulties in support during the process of headbutting, this paper takes the A110607 backwind road of Wenjiaba coal mine as the engineering background and investigates the stability of the roadway surrounding rocks before and after cutting the top during the process of headbutting. The results show that after the pre-cracking top cutting, the stress superposition effect of the overlying rock layer is reduced, and the displacement and stress variation of the roadway surrounding rock drops significantly compared with that when the top is not cut. In the range of 20m to 60m, the deformation of the surrounding rock of the roadway after cutting the top decreases significantly compared with that of the uncut top, with the maximum decrease at 60m lagging, the amount of top and bottom slab displacement decreases by 40.7% and the amount of displacement of the two gangs decreases by 33.3%. The roadway is strongly affected by dynamic disturbance, from the start of digging to the completion of adjacent workings, the roadway needs to experience workings mining disturbance and roadway digging disturbance, which will inevitably cause rock movement along the overlying rock of the roadway, making it more difficult to maintain the roadway. Accordingly, the "unloading - solid - support" synergistic control technology is proposed as the core of the strong mining roadway surrounding the rock structure stability control program. The field application shows that this technology can effectively control the deformation of the surrounding rock of the roadway and achieve the stability control of the surrounding rock of the strongly mined roadway.
- 1
Research on Simulation and Safety Prevention of Underground Water Inflow in Barun open-pit MineAbstract:
The water inflow prediction of open pit mine is a necessary prerequisite for making mine drainage control and dredging scheme. Taking Barun open-pit mine as an example, a 3D groundwater numerical model is established by analyzing the hydrology and engineering geological data of the mine area. On this basis, the prediction of water inflow and regional water balance analysis of water inrush point in mining area are carried out. The research results show that: The simulated water inflow of the mining area is 3903.2 m3/d, and the slope seepage is caused by the uneven recharge and drainage of the upper Quaternary diluvial and alluvial aquifer of the exploration line 28~39 in the north side of the east stope of the mining area. Therefore, the joint treatment scheme of the upslope drainage hole and cut-off ditch is proposed, and the drainage simulation of three exploration line slopes of 28, 32 and 36 is carried out. The simulation results show that: The upslope drainage hole can effectively reduce the groundwater level, reduce slope seepage and improve slope stability. The research method can provide reference for mine flood control.
- 1
Experimental Study on Mineral Processing of a Low Grade Rubidium Polymetallic Ore in Inner MongoliaAbstract:
The main valuable elements of a rubidium polymetallic ore in Inner Mongolia are rubidium and tantalum niobium, with Rb2O and (Ta, Nb) O5 contents of 0.11% and 222.9g/t respectively. Rubidium mainly exists in mica and potash feldspar in the form of isomorphism, and a small amount occurs in albite. Tantalum niobium mineral is mainly pyrochlore. In order to recover rubidium and tantalum niobium resources, mineral processing test research was carried out on the basis of raw ore process mineralogy research. The process flow of "strong magnetic separation+gravity separation to recover tantalum niobium - neutral flotation of rubidium containing mica - fluoride free acid flotation of rubidium containing feldspar" was adopted, the pH value of pulp was adjusted by sulfuric acid, the flotation mica was collected by CK-Y1+DAA, and the flotation feldspar was collected by SDS+DAA. The yield was 0.17%, (Ta, Nb) O5 grade was 4.33% Tantalum niobium concentrate with a (Ta, Nb) O5 recovery rate of 33.22% and a comprehensive rubidium concentrate product with a yield of 70.26%, Rb2O grade of 0.134%, and Rb2O recovery rate of 87.49%. The Rb2O grade in the tailings is 0.045%. We have achieved full recovery of rubidium resources in ores and effective recovery of associated tantalum and niobium resources.
- 1
Experimental Study on the Suppression of Spontaneous Combustion of Low Rank Coal by I-AO Ultrafine Particle AerosolAbstract:
This article discusses the synthesis of a highly effective ultrafine composite aerosol particle for inhibiting coal spontaneous combustion by using iodine-containing inorganic salts (NaI and KI) in conjunction with the antioxidant N-phenyl-1-naphthylamine. The changes in the self-ignition characteristics of treated coal samples and the distribution and quantity of functional groups were analyzed through simultaneous thermal analysis (TG-DTG-DSC) and FTIR spectroscopy. The experimental results show that the activation energy of coal samples treated with both iodine salts and antioxidants increased by an average of 7.22%, 11.14%, and 47.77% in the three stages of water evaporation, pyrolysis, and combustion, respectively. Moreover, the average number of -OH groups decreased by 27.89%, and the average number of oxygen-containing functional groups, mainly including carbon-oxygen bonds (Ar-O-C), carboxyl groups (-COOH), and C=O bonds, decreased by 40.62%. These results indicate that the composite ultrafine particle aerosol formed by the combination of iodine-containing inorganic salts and antioxidants has a significant inhibitory effect on the entire combustion process of lignite.
- 1
Study on the Relationship Between Grinding Fineness and Concentrate Grade Based on Column Low Intensity Magnetic SeparationAbstract:
In order to find the relationship curve between fineness and concentrate grade under the best conditions of column low intensity magnetic separation, optimization tests were carried out on the upflow velocity, coarse magnetic field, sweep magnetic field and magnetic field variation period of column low intensity magnetic separation, and the best parameters were used for different grinding fineness separation tests, so as to fit the relationship curve between fineness and concentrate grade. The results show that under the conditions of rising water velocity of 26.5×10-2 m·s-1, coarse (constant) current 2A, sweep current 1.1A and magnetic field variation period 3s, the ore samples with grinding size (-0.074mm) of 59.64%、81.50%、97.09% and 99.20% are sorted, respectively. The fitting y =〖 A〗_2 + (〖 A〗_1-〖 A〗_2)/(1 + exp((x-x_0)/dx)) theoretical formula of fineness and grade can be written as: Using the fineness test results of 92.65% to verify the error is 0.01%. Combined with VSM and SEM results, it is determined that the optimal feeding size (d50) of column low intensity magnetic separation should be kept at about 25.7μm. The fitting curve can theoretically predict the grade of column separation in advance, provide preliminary research for realizing intelligent column separation by deep learning, and provide theoretical support for magnetic system optimization of column separation equipmen.
- 1
Research on pre-cracking and roof control technology for thick hard roofs without coal pillars under secondary miningAbstract:
Pre-cracking and roof control is one of the main technical means to improve the appearance of strong mineral pressure on thick hard roofs along the adjacent face of the stay-along lane. For Zhangji mine 1615A working face stay lane secondary mining thick hard roof plate difficult bubble fall problem, using theoretical analysis, numerical simulation, field practice method to carry out research. Through theoretical analysis, a mechanical model of the pre-cracked roof of the working face was established, and the expressions for the displacement and pressure step of the roof under four working conditions were obtained, which calculated that the initial pressure step without pre-cracked roof was 50.06m and the periodic pressure step was 21.04m, and the initial pressure step after pre-cracking and blasting was 31.66m and the periodic pressure step was 14.6m. After pre-cracking and blasting, the breakage step was effectively shortened and the peak stress at the working face was reduced by 21.46%~22.52%, which effectively improved the influence of over-supporting pressure; the field monitoring data showed that the pre-cracking and roof control had obvious effect and effectively reduced the phenomenon of mine pressure, which provided reference for similar pre-cracking and roof control at the working face.
- 1
Experimental study on fracture instability law of low double hard roof in extra-thick coal seamAbstract:
Aiming at the problem of overburden rock impact breaking in top coal caving mining with double hard roof in extra thick coal seam and the problems of large deformation of roadway along wide coal pillar, difficult roadway protection and repeated brushing and expansion, taking 14202 working face of Majialiang Coal Mine as the engineering background, through physical similarity simulation experiment, the dynamic load effect of low double hard roof structure breaking in extra thick coal seam is studied and analyzed. The results show that the lower hard roof self-separation layer sprouts to all caving working faces. The cumulative advance is 36 m, and the first instability breaking occurs when the advance is 60 m. The caving thickness is 4.2 m, the breaking angle is 60 °, and the roof fracture line is 5.8 m from the coal wall. With the continuous advancement of the working face, the overlying weak interlayer moves and sinks synchronously with the periodic collapse of the hard roof, forming a "step sinking ", and the periodic caving step is about 23m-25m. The cumulative advance of the upper hard roof from the lower layer to the fully collapsed working face is 23 m, the breaking step is about 55 m ~ 65 m, and the breaking angle remains stable. The displacement monitoring results show that the motion law of the lower hard roof and the middle and lower part of the weak interlayer, the upper hard roof and the upper layer of the weak interlayer and the overlying weak rock layer are consistent. The fracture instability of the double hard roof forms a certain range of stress rise zone on the side of the goaf. The peak stress is 23 MPa, the stress concentration factor is 1.57, and the influence range of the peak stress is 20 m. The lower hard roof breaks to form a " short cantilever beam " structure, which forms a " small periodic weighting " with the dynamic forward movement of the working face, and the upper hard roof breaks to form a " long masonry beam " structure. The structural breaking instability dynamic load acts on the lower " short cantilever beam " so that it breaks in advance and acts together on the working face support to form a " large periodic weighting ". The research results can provide theoretical basis for surrounding rock control under the condition of multi-layer hard roof in extra-thick coal seam mining.
- 1
Residual Ore Recovery Technology and Economic Benefit Evaluation Based on Prestressed Expansion Pillar SupportAbstract:
In view of the problems of high loss rate of original rock pillar, decrease of resource utilization rate and decrease of safety and work efficiency caused by unstable stope mining method, based on the new pre-stressed expandable pillar and the engineering background of the recovery of residual raw rock pillar by overall mining method of Chaihulanzi gold mine, the theoretical calculation and field test methods are integrated. The technology of replacing raw rock pillar with pre-stressed expandable pillar is studied and its economic benefit evaluation is carried out. From the technical perspective, the active supporting force of pre-stressed expandable pillar is 1700 kN and the bearing strength is up to 2800 kN. In the process of field industrial test, the pre-stressed expandable pillar can ensure the stability of stope roof. From the economic point of view, based on the method of replacing the original rock pillar with pre-stressed expandable pillar, the recovery rate of Chaihulanzi gold mine can be increased from about 70% to 92%, and the direct economic benefit is remarkable.The research results can provide a theoretical basis for the safe, efficient and low-cost recovery of residual pillars in Chaihulanzi Gold Mine, and can provide reference for the recovery of residual ore in other metal mines.
- 1
Study on Overburden Fracture Characteristics of Fully Mechanized Caving Mining and the abnormal mechanism in Extra Thick Coal SeamAbstract:
In order to determine strata behavior law and overburden structure characteristics of the working face under fully mechanized top coal caving mining conditions in extra thick coal seams, at the same time to study the abnormal mechanism, on-site measurement and numerical simulation methods were used to elaborate the failure situation of the working face and the stress distribution rules under different advancing distances. Based on the internal and external stress field theory and material mechanics, the formation conditions and geometric characteristics of the cantilever beam structure were obtained, and the fracture location of the key layer was quantitatively explored. Physical simulation was used to verify the key layer fracture structure. The results show that the structure of low cantilever beam and high masonry beam is formed in the overburden strata of fully mechanized top coal caving face in extra thick coal seams. Breaking length of the cantilever beam is 31.5 m, and the cantilever beam breaks 15.4 m away from the coal wall. The increase of coal seam thickness leads to the rotation deformation and instability of key strata, and ultimately forms the cantilever beam structure, which explains the phenomena of intense mining pressure in extra-thick seam.
- 1
Influence of macro-meso parameters of rock block on mechanical characteristic of rock mass in caving zoneAbstract:
The macro and meso parameters of rock block have important influence on the mechanical characteristic in caving zone. The confined compression test of goaf core samples was carried out by using the broken coal rock loading test device. Based on the test results, the PFC3D numerical simulation method was used to reconstruct the core samples in three dimensions, the meso-mechanical parameters of the rock blocks in the caving zone were calibrated, and the numerical simulation of the compressive deformation characteristics of the caving zone at the engineering scale was carried out. The effects of model size, rock block size, bulking factor and meso-mechanical parameters on the mechanical characteristic were analyzed. The linear stress-strain constitutive relation of caving zone is obtained by dimensional analysis. The results of core loading test shows that the loading curve of core sample changes approximately linearly. The compressive deformation characteristics are related to the total length of the columnar core with a diameter of 50 mm. The slope of the stress-strain curve of the sample increases with the increase of the total length of the columnar core. The deformation modulus of the sample increases exponentially with the increase of the length of the columnar core. The numerical simulation results show that the model size, rock block size, bulking factor and effective modulus have significant effects on the compression deformation characteristics of the caving zone. The compression amount of the caving zone increases with the increase of the model diameter and bulking factor, and decreases with the increase of rock block size and effective modulus. However, when the ratio of model diameter to height is greater than 3:1, the influence of model size on the compression deformation characteristics of the caving zone is significantly reduced, indicating that the ratio of diameter to height greater than 3:1 can effectively reduce the influence of model size on the model test results. When the rock block size is greater than 1.3 m, the compression deformation curve of the caving zone changes from exponential increase to linear increase, indicating that as the rock block size of the caving zone increases, the compressibility of the caving zone gradually decreases and the supporting capacity gradually increases. When the bulking factor is lower than 2.0, the compression deformation curve of the caving zone changes linearly. When the bulking coefficient is higher than 2.0, the pore compaction characteristics of the caving zone gradually appear, and the stress-strain curve changes exponentially.
- 1
Study on Flotation Performance and Applicationof a New Fluorite Collector(CYP-01)Abstract:
In order to solve the problems of poor selectivity, low solubility and low temperature resistance of traditional fatty acid fluorite collector, a new efficient fluorite collector(CYP-01)was developed, and its flotation performance, laboratory closed circuit test, field split expansion test and industrial test were carried out. The test results show that (CYP-01)fluorite collector has good low temperature resistance, acid and alkaline resistance, strong collecting ability, good selectivity, easy dissolution and good dispersion. The production technical indexes of (CYP-01)fluorite collector are significantly superior to those of field collector and the original process in industrial application, which reflects the excellent comprehensive flotation performance of the new fluorite collector.
- 1
Accurate Prediction of The Whole Process of nNatural Ignition of Coal Seams Research and Application of Index SystemAbstract:
Spontaneous combustion of coal seam seriously affects the safety of mine production. In order to accurately predict the whole process of spontaneous combustion of No. 3 coal seam in Hanglaiwan Coal Mine, the natural ignition indicator gas of coal seam was measured by temperature programmed experiment, and the suitable indicator gas of spontaneous combustion of coal seam is determined by field test. The critical values of CO index in the upper corner and return air roadway of goaf at different spontaneous combustion stage are predicted by mathematical model. The results show that CO can be used as the main indicator gas in the early stage of spontaneous combustion, C2H4 and C2H6 can be used as the indicator gas in the accelerated oxidation stage of spontaneous combustion, and C2H2 can be used as the indicator gas in the intense oxidation stage of spontaneous combustion. When the coal temperature in the high temperature area of the goaf reaches 50℃, 70℃ and 100℃, the predicted concentration of CO in the upper corner is 56ppm, 76ppm and 5000ppm respectively, and the predicted concentration of CO in the return air lane is 6ppm, 76ppm and 500ppm respectively. An accurate prediction index system for the whole process of spontaneous combustion of coal has been established, and good application results have been obtained through field testing.
- 1
Mechanical Properties and Acoustic Emission Characteristics of Limestone under Triaxial LoadingAbstract:
As one of the widely occurring sedimentary rocks in the mining rock mass, it is crucial to clarify the mechanical properties and damage evolution process of limestone for the safe mining of coal resources. Therefore, in this paper, the triaxial compression test under different confining pressures (5 MPa~30 MPa) was conducted on limestone taken from the floor rock of the return air crosscut in the 81 mining area (-950m) in Huaibei, and acoustic emission (AE) was used to monitor the entire deformation and failure process of the limestone. The test results show that: (1) The stress-strain curves of the limestone can be divided into four stages. Elastic modulus E, poisson"s ratio μ, cracking stress σci and peak stress σf will increase with confining pressure increases, but the closing stress σcc remains unchanged; Stress ratio σcc/σf decreases with increasing confining pressure, σci/σf and σr/σf is not sensitive to changes in confining pressure, cohesion c and internal friction angle φ at the residual stress are reduced by 18.94% and 26.27% compared to the peak stress, respectively. (2) The AE evolution can better characterize the asymptotic failure process of limestone, and the AE evolution laws of limestone under different confining pressures are consistent. The peak value of the ringing count decreases with confining pressure, and the amplitudes are all distributed in the range of 20 ~ 100 dB. The high amplitude AE events in the limestone sample increase with the axial stress loading and exhibit a clustering distribution phenomenon. (3) The damage evolution model established using the cumulative ringing counts as the characteristic parameter can well describe the asymptotic failure process of microcracks closing, expanding, penetrating, and macroscopic failure of limestone under triaxial stress.
- 1
Study on the technical method system of mineral resources supervision in northwest chinaAbstract:
Mineral resources supervision refers to the supervision, inspection and evaluation of the local government"s main responsibilities and regulatory responsibilities of resources protection, development and utilization in accordance with relevant laws, regulations and policies. From 2021 to 2022, the general supervision department of natural resources has passed the pilot project and gradually carried out the of mineral resources supervision nationwide. At present, the mineral resources supervision has been carried out for the first time, and there is no mature experience in working procedures and technical methods. Based on the mineral resources supervision work carried out by Xi"an Bureau of National Natural Resources Supervision in 2022 in northwest China, this paper focuses on solving the problem of "what to supervise and how to supervise?" We comprehensively sorted and summarized the work of mineral resources supervision from aspects such as supervision tasks, problem classification, data sources, problem classification, judgment basis, responsibility division, research and judgment paths, supervision results, existing problems, and policy recommendations, and initially established an effective technical and methodological system for mineral resources supervision. The supervision practice shows that the working procedures and technical methods adopted by the current mineral resources supervision are effective and can meet the needs of the supervision, and provide ideas and method support for the promotion and normalization of the mineral resources supervision work.
- 1
Research on Roof Cutting and Pressure Relief Technology of Dense Drilling in Dynamic Pressure Roadway Adjacent to MiningAbstract:
In order to solve the problem that roadway maintenance is difficult due to the influence of strong dynamic pressure on adjacent mining roadway, theoretical analysis, numerical simulation and field deformation measurement of roadway are used to study the roof cutting and pressure relief technology of 100302 return air roadway in Tanyaoping Coal Industry. It is concluded that: ① after the roadway roof of the advanced working face is arranged with dense boreholes, when the working face is pushed to the nearby area, the mining pressure will make the plastic zone of the adjacent boreholes penetrate to form the directional weak zone, and the roof will be broken in time along the directional weak zone after the working face is pushed, so as to achieve the purpose of roof cutting and pressure relief; ② The key parameters of roof cutting and pressure relief of dense boreholes are determined, and the average dynamic load coefficient is introduced to optimize the traditional spacing formula of dense boreholes; ③ The analysis shows that the peak stress change curve of middling coal pillar in the process of adjacent mining and adjacent excavation decreases as a whole after the pressure relief of dense drilling and roof cutting, that is, the fluctuation time is advanced, the fluctuation range is narrowed, and the fluctuation peak value is reduced; ④ The field monitoring shows that the surrounding rock of the driving roadway in the adjacent working face is within the controllable range after the roof cutting and pressure relief of the dense drilling.
- 1
Statistics of Blasting Fragmentation Distribution Based on Computer VisionAbstract:
Blasting fragmentation is the key data index of mine blasting, which is very important for the evaluation of blasting effect and the optimization of blasting parameters. The traditional fragmentation statistics method has some problems, such as low efficiency and many restrictions. The computer vision method for the statistics of fragmentation of explosive piles has the advantages of high efficiency, accuracy and flexibility. Aiming at the problem of computer vision recognition of fragmentation statistics of blasting piles, a method of fragmentation statistics based on morphology optimization combined with Mask B-R-CNN and HSV transformation was proposed, and the fragmentation statistics of blasting piles in the laboratory and in the mine site of Anqian Mine were experimentally verified. The laboratory experimental results show that the error of the fragmentation distribution statistics is less than 3% compared with the screening method, which verifies the feasibility of this method for the fragmentation statistics of explosive piles. The field experiment of Anshan Mine shows that this method is more accurate than the traditional extraction method of ore and rock area qualitatively. When applied to the mine site of Anshan Mine, the cumulative probability curve of the fragmentation distribution of the three blasting piles is similar, with the lump rate of 4.21%, 3.37% and 3.12% respectively, and the blasting effect is good.
- 1
Study on Overlying Rock Migration Law of Multiple Key Layers Under Continuous Mining in Shallow-buried Thick Coal SeamAbstract:
Taking the 23203 working face of Zhuanlongwan Coal Mine in Ordos as the engineering background, continuous discontinuous numerical analysis and theoretical calculation methods were used to investigate the migration law of overlying rock and the characteristics of rock pressure under continuous mining of shallow-buried thick coal seam in northwest China. The results show that when a shallow coal seam with a depth of 200 m and a thickness of 4.81 m is mined continuously and rapidly at full height, its base-load ratio Jz is greater than 1 and there are three key layer structures. There are three types of self-stable structures in the overlying strata of shallow buried stope under continuous mining, and the periodic fracture of each self-stable structure affects each other. The third periodic collapse form of the direct roof transforms the "masonry beam" structure into the "cantilever beam" structure. The measured resistance values of the support during the mining process of the multi-key layer structure working face mainly range from 11000 to 16500 kN/frame, with an average value of 14077.20 kN, which verified the rationality of numerical simulation, theoretical calculation, and support selection. The research results can provide an important scientific basis for safe mining and support selection in shallow and thick coal seams.
- 1
Study on the Influence of Coal - Rock Dip Angle on the Asymmetric Deformation and Failure of the Gob-Side Coal–Rock RoadwayAbstract:
In order to reveal the influence of coal seam dip Angle on the deformation and failure of roadway retention along the gob, taking Jinqiu Coal Mine in Shandong province as the engineering background, the dip-angle effect of asymmetric deformation and failure of roadway retention along the gob in slow dip coal seam was studied by field investigation, mechanical model analysis and FLAC3D software. The results show that the deformation of the two sides of the slow dip coal and rock strata along the cave-in retaining shows significant asymmetric characteristics. With the increase of each dip Angle, the asymmetric deformation characteristics are aggravated, and the step effect of the coal-rock surface deformation is significant. When the coal-rock dip Angle is greater than 10°, the coal-rock interface of narrow coal pillar has the condition of shear slip deformation. The essence of the slip and asymmetric deformation along the coal-rock interface and the aggravation of the failure characteristics of the surrounding rock on both sides of the roadway is that the tilt of the coal and rock strata leads to the increase of the deadweight stress and the additional stress of the narrow coal pillar along the plane. The research results can provide theoretical reference for the mining and support of gently inclined coal and rock strata.
- 1
Experimental Study on Process Mineralogy and Beneficiation of a Fluorite Ore in Hebei ProvinceAbstract:
The average grade of CaF2 in a fluorite deposit in Hebei is 32.39%, with fine mineral grains and complex embedding characteristics, which is a typical low-grade and difficult fluorite ore. In order to reasonably develop and utilize the deposit, systematic mineralogical research and beneficiation tests were conducted on the ore of the deposit. The results show that the minerals of the ore are mainly fluorite, quartz and a small amount of potassium feldspar and plagioclase, etc. The coarse-grained and pure fluorite content is relatively small, and most of them are microfine grains and complex contact with vein minerals, especially in the close association with quartz, which makes it difficult to separate them. In view of such characteristics of the ore, suitable combination of chemicals and processes were used to carry out the beneficiation process tests, and the optimum flotation conditions were determined with a grinding fineness of -0.074mm accounting for 80%, a water glass dosage of 800g/t and an oleic acid dosage of 600g/t. Under this condition, after the treatment process of one stage grinding, one roughing, one sweeping, six selections and return of the middle ore, a fluorite concentrate with 97.38% CaF2 grade and 82.58% recovery was obtained, which realized the effective utilization of this low-grade difficult fluorite resource.
- 1
Experimental Study on Mineral Processing of a Low-grade Spodumene Ore in Methylka Area in SichuanAbstract:
Li2O grade of a spodumene ore in Sichuan is 1.18%, The main occurrence mineral of lithium is spodumene. Gangue minerals are mainly quartz and plagioclase, followed by Muscovite and Sericite. Under the condition of grinding fineness of -0.074 mm (68.36%), a closed-circuit flotation process with one roughing and one scavenging and two cleaning was adopted. Finally, a lithium concentrate with a yield of 15.76%, a Li2O grade of 6.03% and a recovery of 80.54% was obtained; the high-efficiency recovery of lithium resource is realized.
- 1
Numerical simulation of thermal flow coupling in the heating stage of coal in-situ injection of supercritical water for hydrogen productionAbstract:
The technology of producing hydrogen by in-situ injection of supercritical water into underground coal seams is a new type of coal conversion technology. Based on this part of the problem, this paper puts forward a heat flow coupling mathematical model for the heating stage of coal seam injection of supercritical water, and studies the evolution law of temperature distribution and pore pressure of coal seam and roof and floor strata using numerical simulation method. The results show that after the injection of supercritical water, the temperature and flow rate near the injection well increase rapidly and gradually expand outward. Then the temperature continued to rise to about 1050 ℃ and then did not rise again. The maximum flow rate reached 5.89cm/s, and the flow rate near the injection well decreased slightly over time. The flow rate near the production well showed a negative exponential growth pattern six months ago, and the temperature and flow rate near the production well remained basically constant six months later. The overall pressure rises slowly within one year, and the temperature outside 700m from the injection well changes little within one year.
- 1
CFD Simulation on Diffusion of Ultrafine Aerosol Particles in Goaf of Typical Fully Mechanized Mining FaceAbstract:
To study the fire prevention and extinguishing potential of ultrafine aerosol particles in underground confined space, the migration and diffusion of 5 ultrafine particles with particle size of 1~20μm in the goaf area of typical comprehensive mining face was studied by CFD numerical simulation. The results show that the particle size is negatively correlated with the maximum effective diffusion range and maximum stagnation time of ultrafine particles, when the injection pressure is 4.00MPa, the maximum effective diffusion range of 1μm particles is 210.48m, and the maximum stasis time is 2212106s, the maximum effective diffusion range of 20μm particles is 56.86m, and the maximum stagnation time is 598382s; the application location of ultrafine granular material has a significant effect on the migration and diffusion of particles in the goaf, and the vortex center of the air inlet corner has two sides of the influence on the migration and diffusion of ultrafine aerosol particles in the goaf; the injection pressure of ultrafine particles is positively correlated with the diffusion range of ultrafine particles, and negatively correlated with the stagnant time of particles, among the 3 different injection pressures, the injection pressure of 2.25MPa are the optimal for particle injection, the maximum stagnant time and the maximum effective diffusion range of particles in the goaf is 3429449s and 198.32m, respectively; the porosity of the goaf is positively correlated with the diffusion range of ultrafine particles, when the void fraction is 0.2, the maximum diffusion range is 49.99m, and when the void fraction is 0.4, the maximum diffusion range is 119.88m. This research results provide a theoretical reference for mine fire prevention.
- 1
Stability Evaluation of Filling Body Based on G1 Method and Dolomitization Matter-Element ModelAbstract:
Filling body is the key stope structure in mining, and its stability evaluation is of great significance to mine production safety. In view of the fuzziness and randomness of the current evaluation method of filling body stability, a comprehensive evaluation method of filling body stability is proposed. The comprehensive evaluation model of filling body stability was constructed by using the order relation analysis method ( G1 method ) and the cloud matter element model. Taking a filling body in Daye Iron Mine as the engineering background, the order relation analysis method is used to determine the index weight, the cloud correlation degree and comprehensive evaluation vector of single index are calculated by MATLAB, and the stability grade of filling body in Daye Iron Mine is determined by the principle of maximum membership degree. The results show that the stability grade of filling body evaluated by the stability evaluation method of filling body is consistent with the actual situation, which can provide new ideas and methods for the stability evaluation of filling body in deep metal mines.
- 1
Research on efficient activation and mixing technology of full tailing sand and filling characteristics of homogenized pasteAbstract:
In view of the collapse of the filler caused by inhomogeneous filling, the trajectory of a slurry body in the mixer is simulated by Solidworks and FLUENT numerical analysis software to reveal the intrinsic mechanism of homogeneous filler formation, which is combined with semi-industrial tests to derive the application parameters and effects of the mixer on tailings. The results show that the gum solids, when added to the mixing drum, can be uniformly dispersed in the tailing mortar, forming a homogenised filling body.In this process, the filling slurry undergoes two times of mixing, first moving downward, passing through the flexible blade, then touching the lower rigid blade, and then the slurry tumbles upward, and finally returning to the flexible chain to form eddy current. In order to form a homogeneous filling slurry with good fluidity, the slurry preparation concentration should not exceed 72%, and the mixing frequency should be adjusted relatively according to the actual situation, and it is recommended to keep above 45 Hz. The filler prepared by the mixer has a secretion rate and a sink rate of 3.3% and 4.4% respectively, which do not cause segregation of the underground filler, and the strength meets the mining requirements, which is of guidance for the construction of mine filling systems.
- 1
Simulation study on environmental behavior after backfilling coal mine with solid waste slagAbstract:
In order to fully demonstrate the impact of slag solid waste backfilling on the soil environment after coal mine mining, two important natural aging process experiments were carried out to simulate freeze-thaw and dry-wet cycles. The experiment simulated the situation of coal mine backfilling with slag solid waste. By analyzing the three aging modes of freeze-thaw cycle, dry-wet cycle, and freeze-thaw - dry-wet cycle, the total quantity/acid immersion/water immersion test before and after aging was conducted. The change of environmental behavior of industrial solid waste after aging treatment was analyzed under three aging modes: freeze-thaw cycle, dry-wet cycle, and freeze-thaw dry-wet cycle. Through instrument detection and analysis, the residual state of Pb in slag accounted for 35.97% and 24.41% respectively, and the exchangeable state and residual state decreased after aging. After aging, organic Pb (65.30%) is the main form in the slag. The heavy metal Cd accounts for 43.03% in the residual state before aging, and 33.84% in the carbonate binding state after aging, which is easy to release into the environment. Cu in slag solid waste before and after aging is mainly organic state, after aging the proportion of organic state continues to increase, accounting for 71.21%. Compared with the simulated solid waste from the first year to the fifth year, the migration rate of heavy metals and fluoride in groundwater gradually decreased, which also indicated that heavy metals would migrate further to the southeast of the mining pit over time. The research can provide a scientific basis and reference for the application of slag filling and mining pit treatment technology.
- 1
Experimental Research on Shear Characteristics of Hetergeneous JointsAbstract:
The study of shear characteristics of hetergeneous joints helps to analyze and evaluate the stability of engineering rock masses. In order to study the effects of roughness and normal stress on the shear strength and deformation characteristics of hetergeneous joints as well as the damage characteristics of joints, two sets of direct shear tests on hetergeneous joints were carried out in this paper. The shear stress-shear displacement curve of the hetergeneous joints is a peak-type curve with obvious phase characteristics, and the normal displacement-shear displacement curve shows a trend of shear contraction followed by shear expansion. With the increase of roughness, the peak shear strength and residual shear strength increase. With the increase of normal stress, the peak shear strength, and the decrease of post-peak stress increases, and the high normal stress has an inhibitory effect on the shear expansion effect of hetergeneous joints. The damage coefficient of hetergeneous joints increases with the increase of roughness and normal stress, and the increase of damage area of upper part soft rock is larger than that of lower part hard rock. The damage form of hetergeneous joints is not a single. The shear behavior of the hetergeneous joints damage form is not a single shear, but the result of the composite action of slip, shear, tension multiple damage forms, joints damage mode is divided into shear slip damage, shear cutoff damage, tension damage.
- 1
Study of Digital Drilling Bit Wear in Relation to Follow-on Drilling ParametersAbstract:
The exploration of fast and accurate methods for obtaining in-situ rock mechanics is a matter of interest. With the development of digital drilling technology, more technical means are available for predicting the mechanical properties of rock masses. The inversion of rock mechanics parameters by follow-on drilling parameters is the core problem of digital drilling technology, and the PDC bit is the main structure for rock breaking in digital drilling technology. In order to analyse the influence of the degree of wear of the PDC bit on the drilling parameters that follow it, this paper establishes a digital drilling system based on a hydraulic anchor drilling rig in coal mines on its own. The system was used to carry out digital drilling tests at different levels of bit wear, while the rock breaking process of the worn bit was simulated in conjunction with finite element software to investigate the variation pattern of drilling parameters with the PDC bit under wear conditions. The results of the study show that the correlation between the drilling parameters and the rock strength during the drilling process is significant, the drilling speed increases with the increase in speed and the torque decreases with the increase in speed. Drill bit wear has a significant effect on the drilling parameters. Under the same power and rock strength conditions, the drilling speed decreases with increasing bit wear and the drill pipe torque increases with increasing wear. The test results are consistent with the pattern of variation in the numerical calculations, demonstrating the importance of different levels of bit wear in determining rock properties with digital drilling techniques. The study provides a reference for the rational adjustment of drilling parameters and the inversion of rock mechanics parameters in digital drilling with PDC bits.
- 1
Numerical Simulation of Support Scheme Optimization of Thick Loose Layer and Thin Bedrock Roadway in Zhaogu No. 1 MineAbstract:
The mining problem of thick loose layer and thin bedrock is one of the mining problems faced by coal production in China. Taking the 16081 upper crossheading of Zhaogu No.1 Coal Mine as the research object, five support design schemes were simulated by finite difference software. The support effect of each scheme was evaluated by three indexes of stress, displacement and plastic zone. And the stress and deformation characteristics of surrounding rock were compared with those of unsupported roadway, the optimal support scheme was selected. The results show that: (1) the "anchor net + closed steel frame + floor bolt + floor grouting" strengthening support scheme has better control of the surrounding rock of 16081 upper crossheading; (2) Compared with the unsupported roadway, the vertical stress peak of the surrounding rock of the scheme is reduced, and the stress peak is transferred to the shallow part, which appears at about 2m from the surface of the side. The horizontal stress peak area shifts to the shallow part of the floor, mainly concentrated at about 0.9 m from the center of the roadway floor；(3) Compared with the unsupported roadway, the maximum deformation of the optimal scheme is 21 mm, which is reduced by about 80.9%. The volume of plastic zone of the optimal scheme is only 15.3m3, which is reduced by about 85.6%.
- 1
Study on the correlation between abrasive water jet cutting ability and rock parametersAbstract:
The common rocks within 30m above the Shanxi Group II-1 coal seam were selected as targets for abrasive water jet cutting experiments to correlate the rock mechanical parameters with the depth of the cut, and the inner wall of the cut was microscopically analyzed with the help of VHX-2000 digital microscope. The results show that: the rocks above the coal seam within the study area are mainly siltstone, medium sandstone, mudstone and sandy mudstone, followed by chert and coarse sandstone; the modulus of elasticity of the rocks has the strongest correlation with the depth of cut, but there are also certain rocks whose modulus of elasticity has an abnormal relationship with the depth of cut, followed by compressive strength and tensile strength; it is worth noting that the lithology of the rocks changes, but it does not change the cutting mechanism of the abrasive water jet, the rock crystals mainly occur through crystal fracture and along crystal fracture, and the change of the depth of cut is mainly affected by the rock crystal strength, crystal cementation and crystal diameter and other factors.
- 1
Research and Practice on Optimization Measures of Fan Hole Blasting Fragmentation under the Condition of Broken OrebodyAbstract:
In the mining process of non-pillar sublevel caving method under the condition of broken ore rock in the west second mining area of Longshou Mine, the ore block size is not uniform after fan-shaped blasthole blasting, and the proportion of fine ore in the caving ore reaches 50 % -60 %. The production of a large number of fine ore makes the ore fluidity worse, resulting in high dilution rate and low recovery rate in the stope. Based on the field investigation and theoretical analysis, it is considered that the factors such as large hole density coefficient, high explosive unit consumption and ore rock fragmentation are the main reasons for the large amount of powder ore after the fan-shaped blasting in the second mining area of the west. In order to reduce the unit consumption of explosives under the condition of ensuring uniform charge, measures such as reducing the linear charge density of the blasthole and realizing the interval charge in the medium-deep hole are proposed for the blasting row that has completed the medium-deep hole drilling. For the undrilled approach, the measures of keeping the number of blastholes unchanged and reducing the diameter of the blasthole are proposed to reduce the unit consumption of explosives, and the industrial test of the interval charge scheme in the medium-deep hole is carried out on site. The field test results show that the interval charging scheme in the middle and deep hole can effectively improve the problem of too much powder ore after the fan-shaped middle and deep hole blasting of the broken ore body, so that the proportion of powder ore is reduced by about 75 %, the ore fluidity is significantly improved, and the step ore recovery rate is increased by about 20 %.
- 1
Study on the influence of tooth Angle on energy consumption of vertical shaft impact crusherAbstract:
In order to improve the crushing effect of vertical shaft impact crusher and achieve the purpose of energy saving and consumption reduction, using EDEM Bonding model of material crushing simulation, study the influence of different tooth Angle on crushing energy consumption, puts forward the unit energy consumption as the evaluation index to determine the best Angle of tooth Angle. Firstly, the DEM simulation model is established to verify the reliability of the model; secondly, the Angle of the cutting plate on the number of unit energy consumption. The results show that the cutting tooth Angle is larger than 112°, and the energy consumption is increased. in the Angle of α≤112°, the crushing energy consumption is lower at 107°, so 107° is the best Angle of the cutting tooth Angle.
- 1
Study on conveying characteristics and conveying parameter optimization of full tailings filling slurryAbstract:
In order to explore the influence of various influencing factors of filling materials on the transportation performance of filling slurry in a mine, a design experiment was designed with the concentration of full tailings slurry, the diameter of filling pipeline and the filling flow as the influencing factors, and the transportation performance of filling slurry as the response index. The influence of various factors and interactions on the transportation performance of filling slurry was determined by response surface analysis, and the optimal transportation parameters of filling slurry were determined. The results show that : 1 ) Through the analysis of the particle size and chemical composition of the whole tailings, it is determined that the whole tailings is suitable as a filling material for underground filling ; 2 ) Through the response surface analysis method, the sensitivity factors affecting the transportation performance of filling slurry are pipe diameter, slurry concentration and filling flow. 3 ) The test results and response analysis show that when the diameter of a mine is DN150mm, the best conveying parameters are filling flow 100m3 / h and filling slurry concentration 72 %. At this time, the experimental value of flow resistance is close to the predicted value, and the error is 3.92 %, which indicates that the regression model is reliable.
- 1
Discussion on Design Thrust of Concave-fold Retaining wallAbstract:
Gravity retaining wall has been widely used due to its advantages of local material, convenient construction and good economic effect. There are many styles of gravity retaining walls, but for some retaining walls with a height of more than 20m, the conventional forms cannot meet the requirements of bearing capacity and stability, and concave and concave-fold retaining walls are often used in practical projects. There are no relevant provisions in the specification for the landslide thrust of the concave-fold retaining wall. By analysing the shape and type of the concave-fold retaining wall, it is proposed to divide the last strip of the soil behind the concave-fold retaining wall into blocks, and according to the shape and type of the concave-fold retaining wall The stress analysis of the block, the calculation formula of the landslide thrust of the concave and folded retaining wall is derived, and the calculation formula is applied in combination with the actual engineering. It is a special retaining wall with an arc shape.
- 1
Numerical simulation study on Dynamic pressure relief process of new spare blast proof doorAbstract:
Underground explosion accidents generally occur multiple intermittently, When the first violent explosion causes the explosion door of the coal mine shaft to deform and fail, the spare blast proof door can quickly respond and close the pressure relief path, preventing more serious consequences due to short circuit of the main fan. This paper introduces a new type of spare blast proof door, when multiple explosions occur, the pressure relief form on the spare blast proof door can be automatically opened and reset, ensuring the normal ventilation of the mine during the catastrophe. Computational fluid dynamics (CFD) is used as the main research tool to analyze the safety and reliability of spare blast proof doors under the impact of gas or coal dust explosions. The numerical simulation results show that (1) the pressure relief form of the spare blast proof door can complete the pressure relief within 12ms under the explosion impact; (2) The spare blast proof door can withstand the overpressure impact of 0.8MPa without being damaged; (3) The structure of the spare blast proof door is simple and reliable, and it can be automatically reset by relying on its own gravity to achieve intrinsic safety.
- 1
Investigation on Recognition Technology of Microseismic Events based on Machine LearningAbstract:
To investigate the characteristics of crack evolution in the process of ore body fracture, microseismic monitoring technology is used to monitor the microseismic parameters in the process of rock mass failure. Three-dimensional space cluster analysis of microseismic events by machine learning method. The normal distribution Q-Q diagram is used to describe the three-dimensional spatial distribution characteristics of microseismic events, and the maximum expectation algorithm is used to cluster and identify the located events. The research results show that the microseismic events conform to the normal distribution model in space, the clustering method can effectively divide different areas of rock mass, and the identification results can represent the development direction of dangerous areas, and the areas with high magnitude microseismic events accounting for a large proportion of the risk are higher. The fractal dimension of crack cluster can characterize the complexity of regional crack development, and provide theoretical basis for further research on crack evolution. This study provides a new analytical method for microseismic monitoring of ore bodies, which is of great significance.
- 1
Research on prevention of coal mine general accidents based on GRA and AHPAbstract:
In order to study the characteristics of general accidents in coal mines in China in recent years, the statistics of general accidents in coal mines in recent years was taken as the research object, the characteristics of general accidents were analyzed by trajectory cross model. The analysis model of influencing factors of general accidents in coal mines was constructed. The influencing factors of general accidents were studied by grey correlation analysis. The key points and methods of general accident prevention and control were studied by analytic hierarchy process. The results show that the occurrence of general accidents is inseparable from safety management, and it is closely related to the number of coal enterprises and the number of employees. It is necessary to further improve the efficiency of coal enterprises and reduce operators. The prevention and control of general accidents is greatly affected by intelligent moving frame, intelligent auxiliary transportation equipment, cancellation of single props and winches, correction effect of three violations and mutual supervision of teams. It is necessary to make simultaneous efforts in the control of ' three violations ', risk awareness of workers, intelligent construction, system construction other aspects to improve the prevention and control ability of general accidents in coal mines. Coal mines with general accidents need to analyze from these five aspects, fill loopholes in time, make up for shortcomings, and establish a long-term mechanism for prevention and control of general accidents.
- 1
Study on Influence of Oxygen Concentration on the Adsorption Characteristics of LigniteAbstract:
Coal spontaneous combustion is one of the main disasters threatening the safety of mine production, and oxygen plays an obvious role in regulating the occurrence and development of coal spontaneous combustion, in which coal oxygen adsorption is the key step affecting coal spontaneous combustion reaction. Therefore, taking lignite as the research object, the change rules of coal pore structure parameters and functional groups under different oxygen concentrations were studied by low temperature nitrogen adsorption method and infrared spectroscopy, respectively.The effect of oxygen concentration on coal adsorption capacity and adsorption heat was studied by PCTPro-C80 combined experiment. The results show that the specific surface area and pore volume of coal increase with the increase of oxygen concentration, and the pore volume of coal is mainly mesoporous. With the increase of oxygen concentration, the content of groups such as -Ar-CH, -CH2-CH3 and -OH decreases on the micro level, while the adsorption capacity and adsorption heat of coal increase on the macro level. When the oxygen concentration is 13%, the specific surface area, pore volume, adsorption capacity and adsorption heat of coal show a decreasing trend, and the content of -CH2-CH3 group decreases the fastest, with a decreasing value of 18.11%.
- 1
Experimental Study on Local Risk Reduction of Rockburst in Hard Brittle Purple Sandstone based on Borehole Pressure Relief.Abstract:
Rockburst can cause serious casualties and economic losses. Drilling pressure relief is an effective means to prevent rockburst disaster. Based on acoustic emission and digital image correlation method (DIC), uniaxial compression tests of rockburst were carried out for intact specimens and double-hole specimens with different included angles. The mechanical properties and fracture characteristics of purple sandstone were analyzed, the acoustic emission characteristics were studied, and the pressure relief effect of drilling was evaluated. The results show that the rock exhibits significant brittleness, and the initiation position and failure mode vary with the angle. The time series variation characteristics of acoustic emission of rock can be divided into three categories: calm change-sudden change, slow increase-several sudden changes and stable increase-sudden change. In the near failure stage, the medium amplitude signals are the mainstay, accompanied by some high amplitude signals. The b value of AE generally experiences the evolution process of rising first and then falling. The overall b value with borehole is larger than that without borehole. The maximum value of evolution and the overall value at 45 ° are relatively large, and the development of microcracks is more sufficient. When the angle increases from small to large, the pressure relief effect is first enhanced and then weakened, and the best effect is achieved in the range of 30°~ 45°. The best effect is achieved when the fracture penetration of rock bridge is consistent with the overall shear failure direction of the specimen. The research results can provide theoretical reference for the layout optimization of pressure relief holes.
- 1
Development and application of a new type of self-expanding pressure-resistant flower tube for gas extractionAbstract:
During gas extraction through soft coal seams, under the influence of mining, the borehole is prone to collapse, flower tube blockage, and borehole shrinkage and deformation over time, resulting in low gas extraction efficiency, prolonged extraction cycle, and even the need for additional holes for secondary gas extraction. In order to solve the above problems, a self expanding and pressure resistant flower tube for hole protection was studied, which was expanded into a sphere in the borehole to effectively resist borehole deformation, and the outer steel wire mesh fabric prevented coal collapse, flower tube blockage, and other problems. Compared with the original flower tube in the middle and late stages of gas extraction, the negative pressure action area was increased, which helped to convert the Watts from the adsorption state to the free state, and improved the efficiency of gas extraction. Experimental research shows that: (1) By calculating and comparing the gas emission amount in the middle and later stages, under ideal conditions, when using self-expanding flower tubes, the gas emission amount is 0.22m3/d, while the original flower tube gas emission amount is 0.045m3/d, and the gas emission amount increases by 3.9 times; (2) Using Solidworks/simulation static stress mechanics analysis to simulate the stress on the self-expanding flower tube spring steel sheets, it is found that when applying stress to a single and opposite group of spring steel sheets, the force on the spring steel sheets will be evenly divided and shared by the entire body; (3) Field experiments show that the average gas extraction concentration of the comparison group and the experimental group is close at the initial stage of gas extraction, and after 50 days, the gas extraction concentration of the experimental group is much better than that of the comparison group, and the gas extraction concentration can still remain above 20% in the middle and later stages. The use of expanded flower tubes can resist borehole shrinkage, increase the negative pressure area of drainage in the middle and late stages of drainage, increase gas flow, and improve gas drainage efficiency.
- 1
Experimental study on the performance of coal gangue grout under the influence of particle sizeAbstract:
Crushing particle size is a key parameter that restricts the development of coal gangue grouting and filling technology. Laboratory experiments were conducted to test the flow performance (initial fluidity and flow time), stability (bleeding rate and bleeding speed) and deposition performance (sedimentation duration and cementation rate) of coal gangue grout under the influence of particle size. The results show that: (1) Coal gangue grout with particle size of 20 mesh is easy to plug pipes and has poor pumping performance. The coal gangue grout can basically reach a stable state after 2.5 hours of grouting. (2) There is an optimal particle size when coal gangue grout is used for grouting. When the particle size is 60 mesh, the grout has the best flow, stability and deposition performance, which is the ideal grout for pumping. When the particle size is 80 mesh, the grout is most suitable for blocking the grouting target area. The research can provide reference for the selection of particle size of coal gangue grout, and also provide experimental basis for the large-scale engineering application of coal gangue grouting filling.
- 1
Study on disaster evolution law of water inrush in deep buried roadway near collapse columnAbstract:
In order to study the disaster law of water inrush when deep buried roadway passes through collapse column，based on the stress-damage-seepage coupling model of surrounding rock, FLAC3D software was used to study the temporal and spatial evolution characteristics of displacement, plastic zone, permeability and water inflow of rock mass around collapse column in the process of roadway excavation. On this basis, the influence of different water pressure of collapse column and the minimum clear spacing between collapse column and roadway on the water inrush rule of collapse column was analyzed. The research results show that: (1) when deep buried roadway near collapse column passes through the collapse column side, the displacement of the collapse column side, roof and floor will expand substantially in the direction of the collapse column. Finally, the rock mass between the collapse column and the roadway will slip and become unstable, leading to serious water inrush disaster. (2) In the excavation process of deep buried roadway near collapse column, the characteristics of collapse column water inrush are lag, sudden and large volume. (3) The water pressure of collapse column has an obvious inducing effect on the rock plastic zone expansion and the formation of water-conducting fracture channel in adjacent roadway. When the water pressure exceeds the critical value, the rock between collapse column and roadway will be washed out and the water inflow will increase by transition. (4) The smaller the minimum clear spacing between the collapse column and the roadway, the more forward the time node of water inrush occurs in the collapse column to the roadway, and the larger the water inflow is.
- 1
Analysis on Influencing factors of slope stability in multi-weathered limestone open-pit miningAbstract:
The great loss of people''s life and property is caused by the landslide disaster of limestone open-pit mine with multiple weathering strata. In order to explore the influence of open-pit mine slope stability, the research method combining numerical simulation and theoretical analysis is applied in this paper, and comprehensively analyzes the influence of step height, step slope Angle and step width on slope safety factor. The results show that the order of sensitivity is step width > step height > step slope Angle. The interaction between step height and step slope Angle and the interaction between step height and step width have significant influence on the safety factor of slope. The relative error of the safety factor obtained by the analysis of the optimal combination of slope parameters is less than 1%, and the safety factor surplus is moderate, which indicates that the combination of slope parameters is reasonable and reliable, and the overall slope is stable.
- 1
Calculation Method of Dynamic Stability of Talus Slope under Tunnel Excavation and BlastingAbstract:
Blasting in the tunnel is easy to induce the instability of the portal slope (especially loose accumulation). It is of great significance to study the stability analysis method of the slope under blasting load for perfecting the construction method and design theory of tunnel entry. In this paper, the blasting load in the tunnel is equivalent to the wave stress function, and based on the principle of transfer coefficient method, the calculation method of the stability of the tunnel entrance slope under the action of blasting excavation is established, and the application research is carried out by taking Qiaoping Mountain Tunnel of Yuxiang Expressway as an example. The results show that: (1) under the blasting load of tunnel excavation, the dynamic stability coefficient of the slope of the accumulation layer at the entrance of the tunnel presents an attenuation sinusoidal fluctuation with time, reaching the minimum value in about 10ms and tending to the static stability coefficient after 0.2s; (2) Under the condition that the tunnel is 1.0d(d away from the slope of accumulation layer (D is the tunnel diameter distance) and the slope inclination angle is 25, the safe maximum single-stage explosive amount is 6.5kg；; (3) The greater the slope inclination angle of accumulation layer, the lower the change range of slope dynamic stability coefficient during blasting excavation; (4) The smaller the thickness of the accumulation layer, the easier it is for the slope to lose stability under dynamic disturbance. When the thickness is less than 2.5m, the slope will lose stability during blasting.
- 1
Study of the Effect of Filled Joint on Blast Stress Wave PropagationAbstract:
In order to better reveal the propagation law of explosion stress wave and the propagation process of blasting cracks in the rock with filled joint during the blasting process, the cohesive element based on the law of tensile separation is used, combined with the improved explosion stress wave propagation model, to establish a numerical model of explosion stress wave propagation in filled joints rock. Explosion stress wave shock simulation tests are carried out on rock with different geometric characteristics of joint (thickness, distance between filled joint and blast holes). The research results show that the stress waves reflected by filled joint will increase the peak explosion stress of the rock between blast holes and joint. In the rock with filled joint thicknesses of 2 cm, 6 cm and 10 cm, the peak explosion stress of the rock between the blasthole and the joint is significantly increased, and the peak stress of the rock at 2 cm from the joint surface is compared with The rock without joint increased by 41.8%, 54.9% and 70.2% respectively; with the increase of the distance between the blast hole and the filled joint, the intensity of the reflected stress wave will decrease with the attenuation of the intensity of the blast stress wave, the distance between the filled joint and the blast hole is 40 cm and 60 cm in the model, as the distance from the rock to the joint decreases, the peak stress decreases first and then increases; Reflected stress wave, when the intensity of the reflected stress wave is greater than the tensile strength of the rock mass, it will cause interlacing of layered cracks and radial cracks in the rock between the blast hole and the filled joint, which will aggravate the damage of this part of the rock mass degree.
- 1
Research Progress on Utilization of Coal Gangue by Geological Polymerization ReactionAbstract:
Coal gangue is a solid waste produced in the process of coal mining and washing. The accumulation of coal gangue not only occupies a large amount of land area, but also causes pollution of water, air and soil. The green scale consumption of coal gangue is imminent. This paper summarizes the physical and chemical properties, direct utilization, quality improvement utilization and geological polymerization utilization of coal gangue, and points out that although the direct utilization can absorb coal gangue on a large scale, but most of the direct utilization is rough way such as backfill, road construction, and so on, it can not realize the high value utilization of coal gangue. In view of the special properties of coal gangue, there are many problems such as single applicable raw material and high energy consumption in the utilization process. The geological polymerization reaction utilization is the second generation of green gelling technology after ordinary Portland cement, which has both large-scale consumption and high value utilization of coal gangue. This paper focuses on the utilization of coal gangue in geological polymerization reaction. The preparation materials, formation process, reaction characteristics and mechanism of geopolymer are systematically introduced, as well as its application in main scenes such as erosion-resistant materials, high temperature resistant building materials, solidified heavy metals and radioactive elements. At the same time, it is pointed out that the geological polymerization reaction of coal gangue has a wide range of utilization, a green utilization process and low energy consumption, but there are still some problems such as few industrial tests and difficult to scale promotion. This paper aims to summarize the latest research on the resource utilization of coal gangue and further provide reference for large-scale green consumption of coal gangue.
- 1
Study on the migration and fracture evolution law of overlying strata in close distance coal seam under the influence of karstAbstract:
There are a large number of coal seams in karst mining areas in southern China. The collapse and water storage of karst caves under mining disturbance pose a threat to safety production. Aiming at the mining of close distance coal seams under the influence of karst, taking a mine in Guizhou as the research background, UDEC simulation was used to analyze the influence of karst cave on overburden movement and mining fracture development. The results show that under the condition of two-layer coal mining in karst area, repeated mining aggravates the migration of overlying strata and the development of mining fissures; the maximum subsidence of overlying strata in upper coal seam mining is 3 m, the maximum subsidence of overlying strata in lower coal seam mining is 5.5 m, and the maximum subsidence of working face through karst cave is reached. The fracture development under repeated mining has experienced three stages: generation, expansion and compaction, and the mining fracture is most developed in the karst cave. The cracks of the karst cave caused by mining continue to expand around. When the working face advances under the karst cave, the mining cracks and the cracks of the karst cave are connected. The two mining activities have an impact on the stress distribution of overburden rock. With the development of mining in karst mining area, the phenomenon of stress concentration in karst cave is frequent. Under repeated mining of close-distance coal seams, karst caves have a guiding effect on the expansion of cracks. Mining cracks and karst cracks are connected, which easily leads to karst water entering the working face and poses a safety hazard to coal mining.
- 1
Study on Propagation Law of Blasting Vibration Waves in Filling Body of Drift MiningAbstract:
In the process of underground metal mine mining, blasting vibration caused by drilling and blasting is an important cause of surrounding rock fracture and filling body failure. In order to study the propagation law of blasting vibration in the backfill in the approach mining, the in-situ blasting vibration monitoring was carried out based on the Jiaojia Gold Mine. Based on the reasonable arrangement of measuring points and Sadovsky"s empirical formula, the influence of the propagation medium, the presence or not of the filling body and the thickness of the filling body on the blasting vibration propagation law is compared. The results show that, compared with the blasting vibration propagation in the rock mass, the site coefficient K and attenuation coefficient α of the Sadovsky formula increase significantly when the blasting vibration propagates in the filling body. Compared with the condition without backfill body, the existence of backfill body at the bottom of stope will reduce the production cost of blasting clip, which leads to the reduction of site coefficient K and attenuation coefficient α. In addition, the thickness of filling body mainly affects the site coefficient K, but has little effect on the attenuation coefficient α.
- 1
Comparative analysis of pore structure and permeability of carbonaceous shale under conduction and convective heatAbstract:
Coal bed gas has abundant reserves and its main component is methane, which is a clean energy source in our double carbon environment. Carbonaceous shale is common in the roof and floor of coal seam and is an important research part of coalbed methane extraction by heat injection. In order to study the evolution characteristics of pore structure and permeability of carbonaceous shales at different temperatures under superheated water vapor environment, the carbonaceous shales were grouped into two pyrolysis environments of anhydrous and superheated water vapor, and heated to 300℃, 400℃ and 500℃. The heated carbonaceous shales were grouped by CT scanning and permeability test to obtain the data and compare and analyze the pore structure and permeability characteristics of carbonaceous shales in the environment of no water and superheated steam. The experimental results show that: 1) the development of cracks in carboniferous shale under superheated steam environment is significantly greater than that in anhydrous environment. At 300℃, there is almost no crack in carboniferous shale under anhydrous environment, while the width of cracks in carboniferous shale under superheated steam environment has reached 12μm ~ 58μm. 2) The porosity of carbonaceous shale under the condition of superheated steam pyrolysis is much higher than that under the condition of anhydrous pyrolysis, and the difference between them is nearly 10 times. 3) The permeability of carbonaceous shale in superheated steam pyrolysis environment is much higher than that in anhydrous pyrolysis environment, with a difference of nearly 20 to 50 times.
- 1
Research on bulk rate reduction of deep-hole bench blasting inopen-pit mine by adding satellite holesAbstract:
In order to solve the blasting quality problems of bulk output in deep-hole bench blasting of Xinjiang Jinbao open-pit mine, based on analyzing the location and the reasons of bulk output, considering the physical and mechanical characteristics of mineral rock and the blasting parameters of the original scheme, the optimized blasting scheme is put forward, which adds satellite holes. By adding satellite holes, the charge at the top of the bench is increased, so that more explosion energy is exerted on the top area of the bench. Then the rock is broken more fully under the action of the stress wave and detonation gas energy, with less output of bulk and smaller size of the block. At the same time, because of the presence of satellite holes, the row distance decreases in the process of ignition, and the burden of rock blasting at the top of the bench decreases, making blasting easier. The field tests show that the scheme with satellite holes is adopted under the condition of the same parameters of the main borehole, the average bulk rate being about 13.8%, the bulk output decreasing about 40%, and the blasting quality is obviously improved. Although the explosive consumption has increased, it is still more economical than the comprehensive cost of secondary crushing, shoveling and transportation. The scheme with adding satellite holes can provide reference for the reduction of bulk rate for deep-hole bench blasting in open-pit mine.
- 1
The Status and Ecological Restoration Countermeasures of Historical Mines in Hunan ProvinceAbstract:
Carrying out ecological restoration of historical mines is an inevitable requirement to adapt to the construction of ecological civilization, and an important measure to solve the difficult problem of ecological environmental protection measures in mine sites. It is imminent to find out the situation. On the basis of remote sensing monitoring, through data collection, field verification and other investigation methods, it has been found that the untreated historical mines are 109.17 km2 in the province, which have a serious impact on the topography, land resources, water resources, water ecology, the production and living safety of residents and biodiversity, and urgently need to be rectified. Based on the statistical analysis of the status and characteristics of mines, research literature, combined with the actual situation of Hunan province, this paper discusses four obstacle factors to the ecological restoration of historical mines, and proposes four working ideas and five countermeasures, in order to provide reference for scientific planning and implementation of ecological restoration of mines during “The 14th five-year plan period”, and further build a solid ecological barrier in Hunan province.
- 1
Study on the migration law of mechanized mining coal body in pseudo-inclined working face of steep coal seamAbstract:
The accumulation and slip of broken coal in mechanized mining of pseudo-inclined working face in steep coal seam is easy to cause problems such as channel blockage in working face. In this paper, taking the 11807 working face of a mine in Guizhou Province as the engineering background, the combination of physical experiment and numerical calculation is used to study the layout parameters of the working face, the evolution of the interface of the coal body to be mined and the migration characteristics of the coal body. The slip and accumulation characteristics of the pseudo-inclined working face in the steep coal seam are revealed, and the reasonable layout parameters of the working face angle are determined. The results show that when mechanized mining is carried out in the pseudo-inclined working face of steeply inclined thin and medium-thick coal seams, a large number of cracks are generated in the coal body of the mining area under the cutting action of the plow, and the disturbed stress and deformation space are provided to the unmined area, so that the coal body is relieved and broken. After part of the coal body in the working face is mined, the stress environment of the surrounding rock changes, and the pressure of the roof and floor acts on the coal body to cause deformation and failure of the coal body in the non-machine mining area, and the coal body is broken. The movement of broken coal in the mining area is mainly along the vertical direction of the chute. The loose broken coal in the mine pressure self-sliding area first produces the movement perpendicular to the roof, then the inclined movement parallel to the roof direction, and finally the inclined direction of the working face. Accelerated migration, the migration trajectory of broken coal has obvious unity in the working face; the coal seam dip angle of chute working face is linearly related to the slip angle. The greater the dip angle of the working face, the higher the relative recovery rate of coal resources; the dip angle of the working face is determined to be 32°, and the pseudo dip angle is 49.7°. Field practice shows that the effect of coal sliding in working face is good.
- 1
Research on Automatic Loading Control of Underground Scraper Based on Intelligent Drag-reduction StrategyAbstract:
The bucket,s mechanical properties of the underground scraper are complex and changeable in the process of shoveling and loading. The operator of the cab can only operate the bucket by real-time observation and judgment with the help of his working experience, so the actual effect is not ideal. Based on the study of mechanical properties in shoveling process, this paper presents an automatic shoveling control method of underground scraper based on intelligent drag-reduction strategy, which can complete the automatic control of shoveling process with high efficiency and low consumption. Based on the timing feedback, through the cooperation of lifting bucket or prying bucket several times during shoveling process, the dense core in the material pile is destroyed continuously and the shoveling resistance is reduced to improve the full bucket rate and the working efficiency of the scraper. At the same time, based on the software of EDEM, the intelligent drag-reducing shoveling process simulation research is carried out, and the automatic shoveling control system is built on the project scraper. Through human-machine interactive programming control to carry out field engineering practice,the effect is stable, the reliability is high, completely satisfies the industrial application.
- 1
Research on the Effect and Problems of Mining Rights Holders Credit SupervisionAbstract:
The State fosters the information publicity system of national mining rights holders for exploration and mining which is the significant part of the management of mineral resources and to deepen the reform of government functions including the reforms to streamline the government. It has practical significance to study the effectiveness of the information publicity system of mining rights holders for exploration and mining in the past six years. Based on the information publicity data of national exploration and development from mining rights holders, in view of social benefits, economic benefits, regulatory efficiency and other aspects, the behaviors of mining rights holders were analyzed from the rate of aspects of publicity , performance of obligations , probability of verification visits and so on, reported the effect of mining rights holders credit supervision. The result shows that the implementation effectiveness in promoting credit consciousness, reducing management costs and starting social public supervision has been preliminarily demonstrated that is the part of credit supervision. However, there is room for improvement in the aspects of service achievement , credit grading, incentive for keeping faith and joint punishment. Through the integration and classification of problems, this paper puts forward some suggestions on improving credit supervision and extending credit service, so as to promote the perfection of the credit system of mining rights holders.
- 1
Experimental Study on Shear Mechanical Properties and Weakening Behavior of Sawtooth Structural Plane with Different Fluctuation AnglesAbstract:
In order to study shear mechanical properties and weakening behavior of rock mass with sawtooth discontinuity, direct shear tests of sawtooth discontinuity under different relief angles and different shear displacements were carried out using a self-developed rock compression-shear servo test system. The experimental results were concluded as follows. Firstly, the shear stress evolution curve is "wavy" when the structural plane undation angle is 15°. When the fluctuation angle is 30° and 45°, the shear stress evolution curve shows a "peak type" and the shear stress evolution of the structural plane with 45° fluctuation angle shows an obvious double peak phenomenon. With the increase of the fluctuation angle, the peak shear stress shows an increasing trend. Secondly, when the relief angle is 15°, the weakening mode of the structural plane is climbing wear; when the relief angle is 30°, the weakening mode of the structural plane is mainly cutting and filling; when the relief angle is 45°, the structural plane is mainly cutting damage in the early stage and sliding wear in the late stage. Thirdly, the damage coefficient R of structural plane gradually increases with the increase of shear displacement, and the larger the fluctuation angle, the larger the value of R, indicating the deeper the weakening degree. The weakening rate of the structural plane at the shear displacement of 5 mm is all above 50%. The research results can provide reference for stability analysis of engineering rock mass.
- 1
Roadheader integrated positioning method based on fusion of SINS and binocular odometerAbstract:
In order to meet the requirement of accurate position sensing of roadheader in mines, an integrated positioning method of roadheader based on fusion of SINS and binocular odometer is proposed. The idea of this method is to introduce binocular odometer as an auxiliary positioning system based on SINS to reduce the influence of cumulative inertial guidance errors on the positioning accuracy of roadheader. A Kalman filter with 15-dimensional state volume is designed to fuse SINS with binocular odometer data and correct for SINS error with an output correction.In order to verify the accuracy and reliability of the integrated positioning method, an experimental platform was built and experiments were conducted. The maximum errors of integrated positioning in northward, eastward and skyward displacements are 0.0339m, 0.3115m and 0.0165m, respectively, and the maximum errors of roll angle, heading angle and pitch angle are 0.1356°, 0.8290° and 1.2200°, respectively.The experimental results show that the integrated positioning method can effectively weaken the cumulative SINS errors and achieve high accuracy positioning of the roadheader.
- 1
Evaluation and Optimization of Drainage Scheme Based on CBM Well Production DataAbstract:
In order to achieve continuous high and stable production of deep coalbed methane Wells, the production data of deep No. 8 coal seam in Daning-Jixian block is analyzed. Considering that the production process parameters such as bottom hole pressure, pump efficiency and casing pressure are important factors affecting the production of coalbed methane well, the production model of coalbed methane well is established by using random forest optimized by genetic algorithm. Based on the model, the theoretical maximum daily gas production and optimization indexes of coal-bed methane Wells with similar geographical location, same batch production and same hydraulic fracturing plan but different production capacity are calculated, and the optimization scheme of coal-bed methane well drainage and production process parameters is given. The results show that the calculation results of coalbed methane well output obtained by the model are of high accuracy, and the optimized values of casing pressure, bottom hole pressure and impact times given for the production of coalbed methane well at the stage of production plunge have certain guiding significance for actual coalbed methane well production.
- 1
Study on the Effect of Fracture Evolution on Seepage Characteristics of Single Fracture Granite under Heating and CoolingAbstract:
In order to study the surface morphology evolution characteristics and hydraulic flow characteristics of single rough fracture under high temperature and high pressure, single fracture seepage experiment of temperature cycle was carried out under different stress and osmotic pressure conditions. The surface evolution characteristics of fracture after rising and cooling were described by three-dimensional topography scanning technology. Its influence on the seepage characteristics of single fracture granite was analyzed. After the seepage action of high temperature and high pressure, the local body of the fractured surface of the single fractured granite destroyed, and the height of the contour decreases, the fracture surface contour becomes smoother; Under different triaxial pressures, the hydraulic fracture aperture and permeability coefficient drops first and then increase with the increase of temperature, with the decrease of temperature, the hydraulic fracture aperture and permeability coefficient at the same temperature are higher than those at the heating stage; The hydraulic fracture aperture and seepage coefficient increased with the decreased of the overall roughness of the fracture surface, which is subjected to the irreversible thermal destruction of the action of high temperature and high pressure seepage.
- 1
Influence of Leaching Agents on Wettability During Leaching of Ionic Rare Earth OresAbstract:
: In this thesis, an ionic rare earth ore in Dingnan County, Ganzhou City, Jiangxi Province, was studied. The effects of ammonium sulphate, magnesium sulphate, calcium chloride and deionised water on the microscopic morphological changes of mineral particles during the leaching process and on the wettability of mineral particles at different concentrations and pH conditions were investigated, and the wettability kinetic equations were established on the basis of the analysis of the mechanism of the leaching agent wettability of ionic rare earth ore. The results of the study show that the minerals produce accumulation and gradual wetting within 0-1min, swelling and dispersion of the ore bodies occur within 1-10min, and pore fissures are produced, and the structure of the ore bodies basically does not change after 10min. Through the contact angle and adhesion work data can be seen, the concentration at 0.3 mol/L is the best wettability, the best permeation effect, the overall size relationship: deionised water > ammonium sulphate > magnesium sulphate > calcium chloride; acidic conditions under the mineral particles wettability better. The analysis of the wetting kinetic equation shows that deionised water has the best wetting performance with a K value of 1.25182, followed by ammonium sulphate, followed by magnesium sulphate, and calcium chloride is the worst with only 0.35568.
- 1
Numerical Simulation Study on Permeability Enhancement of Soft Coal Seam by Blasting with Slit Charge with Co-ntrol HoleAbstract:
In order to explore the anti-reflection effect of blasting under the coupling action of slit charge pack and control hole, a numerical analysis model was established and solved by using ANSYS/LS-DYNA numerical simulation software, and the crack propagation and stress distribution characteristics of anti-reflection effect on soft coal seam under the joint action of slit charge column blasting and control hole were obtained. The results show that the blasting effect of directional control of fractured soft coal seam under the coupling action of slit charge pack and control hole is better than that of single slit charge column. When the stress wave propagates to the control hole, the reflection superposition of the wave occurs, the peak of tensile stress increases, and the deflection of the burst crack is obvious. The control hole plays a guiding role in crack propagation and further promotes the development and propagation of crack. The research results can provide theoretical basis and data support for the engineering practice of soft and low permeability coal seam with blasting permeability improvement.
- 1
Study on flotation separation mechanism of waste lithium electric materials enhanced by interfacial hydrophobic modificationAbstract:
In order to effectively recover lithium cobaltate (LiCoO2) from waste lithium-ion batteries(LIBS), a new type of flotation inhibitor was prepared by dissolving catechol and sodium iodate (CA-SP) in sodium acetate buffer solution, which selectively inhibits the flotation of cathode electrode materials. The anode and cathode electrode materials were separated successfully by reverse flotation, and the cathode electrode materials were collected in tailings. The cobalt-rich concentrate can be obtained by flotation, and the concentrate grade and recovery are 90% and 83%, respectively. In this paper, X-ray photoelectron spectroscopy (XPS) and ultraviolet spectrum (UV-vis) were used to characterize the adsorption mechanism of Catechol (CA)- sodium iodate (SP) on polyvinylidene fluoride (PVDF), LiCoO2 and graphite surface. Finally, it is concluded that CA-SP, as an effective cathode material inhibitor, has the advantages of low cost and friendly environment, and has a good application prospect in industrial battery recycling.
- 1
Study on Overlying Rock Caving Law of Caving Mining in Metal Mine Based on Field Monitoring DataAbstract:
To reveal overlying rock caving law in underground caving mining of metal mines, taking the mining of underground main ore body of Dahongshan Iron Mine as an example, the natural caving and continuous caving of overlying rock were distinguished by the "caving arch" theory. Based on the roadway observation and borehole detection data, the development process and law of overburden caving were obtained. The results show that with the continuous caving and mining of the ore body, the overburden will fall naturally and continuously, and finally penetrate the surface, which is consistent with the field observation results. With the first mining of 480-section and the annual average ore yield of 940000 m3, according to the half-year rate of the overburden caving height, the development process of overburden caving can be roughly divided into the following two stages, namely, the rapid caving stage (68.3m/half year) and the uniform low-speed caving stage (28.65m/half year). The empirical formula of the lag time of overburden caving to the surface in Dahongshan Iron Mine caving method is obtained, which can provide useful guidance for dynamic optimization of space-time mining sequence for open-pit and underground combined mining in Dahongshan Iron Mine.
- 1
Development and Application of Similar Material Specimen Preparation Device for Two-way Equal Pressure Digital DisplayAbstract:
As a scientific research method, similar material simulation experiment has been widely used in the field of mining engineering to study the mechanical properties of roadway surrounding rock and roof and floor rock. However, the similar material specimens prepared by the traditional similar material specimen preparation device have problems such as uneven compaction and looseness, resulting in large dispersion of mechanical properties of the prepared specimens. In view of the above problems, this paper developed a two-way pressure equalization digital display similar material specimen preparation device, which can realize two-way pressure equalization, real-time pressure display, automatic demoulding and other functions. In order to verify the applicability and reliability of the device, the preparation and uniaxial loading test of similar material specimens were carried out. The test results show that compared with the traditional mold, the appearance of the similar material specimens prepared by the device is uniform and dense, the size is uniform, the loading surface is flat, and there is no corner missing phenomenon; he stress-strain curve of the specimen is regular, and the physical and mechanical properties are stable. The failure characteristics of the specimen are obvious, the test results are more stable and the test data are more reliable. The development of the device overcomes the shortcomings of large labor consumption and low preparation efficiency in the preparation process of the traditional device. It is of great significance to improve the preparation efficiency of similar material specimens and reduce the discreteness of experimental results.
- 1
Study on the Mechanism and Parameter Optimization of Non-blasting Intensive Drilling Top CuttingAbstract:
In order to solve the problems of safety of blasting roof cutting in gas accumulation area and limitation of hydraulic fracture in mining fracture development area, we studied the mechanical structure of roof plate during roof cutting and uncutting along the empty retention lane, the mechanism of roof cutting by non-blasting intensive drilling and the parameter optimization of roof cutting drilling. Using the method of stress concentration around the borehole to crack the surrounding rock, the mechanism of dense drilling to cut the roof was analyzed, and the effect of dense drilling to cut the roof along the reuse lane of the 3202 inlet windway of Dongfeng coal mine was studied with the numerical simulation software 3DEC, and the parameters were optimized. The research results show that: when no drilling is done to cut the roof, the top plate of the stay lane sinks seriously; when the diameter of the drilling is 110 mm and the spacing is 150 mm, a dense drilling weakening zone can be formed; the rock layer between the drilling is broken obviously; when the drilling height is 22 m and the angle of drilling is 80° in elevation, the basic top rock layer collapses completely and the displacement of the top and bottom plate of the stay lane is reduced obviously.
- 1
Study on The Mechanism of Vertical Crack Propagation under Low Confining Pressure Biaxial CompressionAbstract:
The surrounding rock in rock engineering such as underground cavern excavation is usually in a state of bidirectional compressive stress. It is of practical significance to study the crack propagation under this stress state. Taking the rock mass samples with vertical cracks under low confining pressure triaxial compression or uniaxial compression as the research object, the distribution law of distal axial compressive stress and crack tip stress under different Poisson 's ratio ? and crack trace length a is analysed by numerical simulation. Based on the superposition principle, the expression of near-field stress at the tip of vertical crack / wing crack under biaxial compression is obtained, and the stress intensity factor and crack propagation direction of cracked rock mass specimen under this stress state are proposed. The results show that Poisson 's ratio and crack trace length a have a significant effect on the stress distribution at the crack tip when there is a distal axial compressive stress. The ratio of the stress at the crack tip to the axial compressive stress parallel to the crack surface has a linear function relationship with the Poisson 's ratio and a cubic function relationship with the crack trace length.
- 1
Study on process mineralogy and beneficiation test of a foreign hematite oreAbstract:
The TFe grade of a foreign iron ore is 49.04%. It is mainly dominated by hematite with a distribution rate of 91.49%, which is patchily and granularly embedded. In this paper, the beneficiation test was carried out by the "stage grinding-stage strong magnetic" process. The iron ore concentrate with 65.26% TFe grade and 74.40% total recovery was obtained under the conditions: 55% of particles less than 0.076 mm in the first stage grinding, 857 kA/m in the strong magnetic roughing field, 65% of particles less than 0.076 mm in the second stage grinding, the strong magnetic selection field strength was 239 kA/m, the strong magnetic sweeping field strength was 477 kA/m. In order to achieve comprehensive utilization of tailing resources, sand fishing test was conducted and obtained 41.47% TFe grade of coarse sand, which can be returned to grinding operation; 13.10% TFe grade of fine sand, which can be used as construction material; 35.55% TFe grade of fine tailing, which can be re-elected for tailing or used as iron correction material for cement.
- 1
Research and application of secondary recovery method of residual ore in footwall of stope with sublevel cavingAbstract:
When mining inclined ore body with sublevel caving method, it is easy to produce residual ore loss at the footwall. First of all, the influence of orebody thickness, orebody dip angle, sublevel height, drift spacing and other factors on the percentage of footwall residual ore is analyzed theoretically. The analysis results show that the footwall residual ore decreases with the increase of orebody thickness and dip angle, and increases with the increase of sublevel height and drift spacing. Then, under the condition of inclined medium-thick ore body, the proportion of residual ore in the footwall when the footwall rock cutting is retreated to different positions is analyzed. The result shows that the full recovery of the footwall ore can not be achieved by using only the medium-deep hole rock cutting mining, and the proportion of residual ore in the footwall usually reaches 10%~15% of the segmented ore, or even higher. In order to fully recover the residual ore in the footwall, the technical scheme of "footwall rock cutting withdrawal+auxiliary route recovery of residual ore in the footwall" has been put forward. The effectiveness of this scheme has been verified by physical ore drawing simulation experiment. The experimental results show that compared with the single medium deep hole footwall rock cutting withdrawal method, this scheme can increase the ore recovery rate by 6.4%, while the dilution rate only increases by 0.4%. Finally, the scheme is applied to the field production practice and has achieved good application results.
- 1
Experimental Study on Reducing Molybdenum Loss from Desliming with a New Type of Backwater Treatment AgentAbstract:
A molybdenum mine in Chengde is mainly composed of molybdenite, and the gangue minerals are mainly talc and serpentine. A process flow for flotation of molybdenum after the removal of talc and serpentine by desliming process is adopted. In order to solve the problem of high molybdenum loss rate caused by residual chemicals in backwater during desliming operations, a new backwater treatment agent CK-J1 has been developed, which can efficiently and rapidly degrade residual chemicals in backwater. The results of closed circuit test show that adding 1000 g/t of CK-J1 to the backwater can reduce the loss rate of molybdenum in the desliming product from 13.14% to 5.71%, and increase the molybdenum recovery rate of molybdenum concentrate from 72.01% to 78.40%.
- 1
Reconstruction and Feasibility Study of Circulating Preheating Ventilation System in Hongtoushan Copper-zinc MineAbstract:
After filling the upper goaf of Hongtoushan Copper-Zinc Mine, the winter preheating and anti-freezing system is facing failure. By using multiple middle shaft and roadway projects in the upper constant temperature zone and warming zone, the exposed area of preheating rock wall is increased, and the reconstruction and feasibility study of circulating preheating ventilation system are carried out. The results show that the preheating circulation ventilation system is reconstructed in Hongtoushan copper-zinc mine, and the west air shaft is changed into the air inlet shaft. The inlet air temperature is -25℃ and above. The total amount of preheating air in the preheating circulation ventilation system is greater than 124.3m3/s. The air temperature can reach 4.43℃ after preheating with the total air volume of 120m3/s in winter, which is 2℃ higher than that of the anti-freezing well. The preheating effect of Ventsim thermal simulation is remarkable, which can effectively solve the problems of shaft freezing, shaft jam and water pipe freezing in winter, and can save 7.54 million yuan per year in energy consumption economy.
- 1
Wear Analysis of Impact Hammer and Rotor Structure Optimization of Vertical Shaft Impact CrusherAbstract:
In the working process of the vertical shaft impact crusher, the impact hammer is seriously worn and needs to be replaced frequently, which greatly reduces the operation efficiency of the crusher . In order to reduce the wear of the impact hammer and ensure the crushing effect of the crusher,the wear model of the impact hammer was established by discrete element method, and the structural parameters of the crusher rotor were optimized by orthogonal tests, regression analysis and multi-objective optimization. The results show that the wear depth of the impact hammer is smaller when the rotor diameter is 790mm,the Installation angle of the guide plate is 37.2°and the height of the split cone is 37.9 mm,and it will not reduce the crushing effect of the crusher,which provides a theoretical basis for the optimal design of rotor wear resistance of the vertical shaft impact crusher.
- 1
Optimization and Application of Curtain Grouting Technology in Complex large Water Mines Near the Ore BodyAbstract:
To further improve the application effect of curtain grouting technology in the underground near ore bodies of large water metal mines, the grouting and water plugging scheme and the grouting process should be optimized in conjunction with the actual mine, and comprehensive analysis should be made according to the mine"s situation and one mine"s policy. Summarizing the practice of underground water treatment project in the East Maanshan ore body of Anqing copper mine, the optimization plan of zoning treatment + local near ore body curtain grouting technology is proposed for the complex hydrogeological conditions, uneven development of karst and strong water-rich permeability in the area. The analysis of the geology, water influx, and borehole data has been established to identify the degree of fissure development in the study area; to determine the bad structure pattern and water-rich spatial distribution, optimize the slurry plugging parameters, and form the optimization plan of near ore body curtain with the technical idea of , inspection borehole comparison, etc. The study shows that: the curtain grouting scheme of the East Maanshan ore body from -580 to -820m in the middle section with partial near ore body has reduced the annual water influx by 36.5%, and the curtain grouting has been effective in reducing water, which has solved the threat of sudden water in the mine and achieved greater benefits for the mine, and can provide a reference for similar engineering practice.
- 1
Strength evolution and mesoscopic damage mechanism of cemented backfill under brine corrosionAbstract:
To study the halogen corrosion mechanism of artificially filled pillars in underground mining area and provide technical reference for improving the corrosion resistance of materials, mechanical properties and fine microstructure of materials under different corrosion time conditions were studied. Uniaxial compression test and computer tomography scan test were carried out to obtain the damage law of backfill strength and microstructure, and the microscopic mechanism of halide corrosion was analyzed combined with the microscopic images. The results show that as the corrosion time increases from 0d to 360d, the compressive strength and elastic modulus of the cemented backfill gradually decrease, and the rate of corrosion slows down first and then increases. The meso-crack of the backfill expands gradually with the increase of corrosion time, and the surface crack rate calculated by CT scan images shows an exponential growth trend, indicating that the structural damage degree of the backfill is constantly increasing. Appropriately increasing the mass fraction of filling slurry is beneficial to improve the mechanical properties of materials and reduce the crack rate. The negative linear correlation between the compressive strength and the surface crack rate obtained from the test indicates that it is reasonable and feasible to use CT image to predict the strength reduction law of cemented backfill in the process of halogen corrosion. Through the morphological analysis of microstructure, it is found that the invasion of corrosive halide ions and chemical action reduce the bonding degree of cemented body, which is the fundamental principle leading to the strength weakening of Sanshandao cemented backfill body.
- 1
Control Analysis of Surrounding Rock of Roadway Based on Miniature Rock MechanicsAbstract:
In order to study the mechanical characteristics and deformation control of the surrounding rock of the roadway, the failure characteristics of the surrounding rock of the roadway were studied by using theoretical analysis, rock mechanics test, numerical simulation and on-site industrial practice research methods using the research methods of theoretical analysis, rock mechanics test, numerical simulation and on-site industrial practice. The results show that the coal body is mainly subjected to tension failure and shear failure, and the damage near the unloading surface is more serious, the support design adopts the bolt anchor cable joint support method, and the numerical simulation test shows that the length of the bolt is 2.8 m, the stress peak of the two sets is the smallest, the stress peak of the solid gang is 27.5 MPa, the stress peak of the coal column gang is 30.81 MPa, and the stress peak area is near the anchor end of the bolt, and the stress concentration effect of the right coal column gang is greater than that of the left gang solid gang. More displacement is generated, and the amount of surrounding rock deformation of the overall roadway is within the control range. The failure law of the roadway is revealed, and the peak stress of the surrounding rock is reduced by designing and optimizing the anchor support scheme, and the deformation of the surrounding rock is effectively controlled.
- 1
Statistical Analysis And Preventive Measures of Non-coal Mine Safety Accidents in Hunan ProvinceAbstract:
In order to study the relationship between various types of safety accidents and the total number of accidents in non-coal mines in Hunan Province, the data of safety accidents in non-coal mines in Hunan Province were statistically analyzed, and the correlation between the number of accidents, the number of fatalities and the total number of accidents, and the total number of fatalities in various types of accidents was analyzed using SPSS26, and the preventive measures for safety accidents were studied. Research shows that roof fall and wall fall are the safety accidents with the largest number of accidents and deaths in the past ten years; In Chenzhou, Xiangxi and Changde, the total number of accidents and deaths accounted for 43.97% and 42.05% of the province respectively, which should be the focus of monitoring; There is a power function relationship between roof fall and wall fall and the total number of accidents, and the correlation is very significant; There is a cubic function relationship between falling from height and the total number of accidents, and the correlation is significant; Non-coal mines in the province should strengthen safety management in technology and management, and build a dual prevention mechanism to prevent safety accidents.
- 1
STUDY ON SAFE AND EFFICIENT MINING METHOD OF STEEPLY INCLINED MEDIUM THICK OREBODY UNDER COMPLEX CONDITIONSAbstract:
Dangping Tungsten has been using traditional mining technology for many years. In practice, the problems of low production capacity, low labor efficiency, poor safety conditions and high labor intensity are increasingly prominent. In order to find a safe and efficient mining method suitable for the steep and medium-thick ore body of the mine, the medium-diameter deep-hole mining technology is proposed on the basis of the large-diameter deep-hole mining technology, and representative ore blocks under complex conditions are selected to carry out on-site industrial tests. The test results show that the medium-diameter deep-hole staged open stoping method is an advanced and reasonable mining method. Compared with the staged open stoping method, the ore block production capacity has doubled, the mining cost has decreased by 15.47%, the explosive unit consumption has decreased by 11.76%, and the loss rate and dilution rate indicators have been greatly optimized, creating good economic and social benefits, which is of great significance for the promotion of small and medium-sized mines.
- 1
Research on Recovery of valuable minerals from waste rock in Durong Mining Areahongyonghua, 兰希雄, 谢 贤, 甘云霄, 陈华萍, 王丛正
Abstract:
In the process of mining, waste rock containing a small amount of valuable minerals will be produced. With the gradual consumption of industrial ores, the recovery and utilization of valuable minerals in the waste rock will become inevitable. Taking the drainage waste rock in Durong mining area as the research object, using the technology of "photoelectric separation + magnetic pulley + dry magnetic separation", the drainage waste rock was divided into three particle sizes: -150mm ~ +25mm, -25mm ~ +10mm and -10mm. The test results of the whole process show that when the zinc grade is 0.408%, Cu grade is 0.045% and Sn grade is 0.044%, the coarse concentrate with Zn grade of 1.781%, Cu grade of 0.159% and Sn grade of 0.153% can be obtained. The recoveries were Zn51.57%, Cu42.81% and Sn43.14%. The research results are of great significance for the deep exploitation of mineral resources, the extension of mine service life and the sustainable development of enterprises, and have a good demonstration effect and application prospect.
- 1
Effect of particle breakage on pile bearing capacity in calcareous sand foundationAbstract:
Particle breakage leads to a significant reduction in the pile bearing capacity of foundations. In this paper, a discrete element program is used to simulate the pile driving process of calcareous sand foundation against the background of low pile bearing capacity of calcareous sand. The results show that during the pile driving process, the soil particles at the bottom of the pile move downwards and the soil on the side of the pile moves upwards to form a particle ‘flow channel’, and the compression effect caused by particle breakage causes the ‘flow channel’ to move towards the pile body. Particle breakage is concentrated within 0.5 times the pile diameter from the base of the pile and near the side of the pile. The reduction of the pile bearing capacity is about 70% due to particle breakage, mainly due to the fragility and high compressibility of calcareous sand. The research results can be used as a reference for the pile construction of calcareous sand foundations.
- 1
Study on Sulfate Resistance of Cement Composite Filling MaterialAbstract:
In order to solve the problem of instability and even decay of the strength of the filler under the erosion effect of rich mine water ions, the study of the filler''s resistance to sulfate erosion was carried out. The alkali-excited filling materials were prepared using coal gangue, blast furnace slag, calcium carbide slag, and water glass, and the filling body compressive strength tests were carried out at different ages (3, 7, 28, and 56 d) and concentrations (0, 2, 4, 6, 8, and 10%) of sulfate immersion, and the mechanism of hydration products was revealed by SEM scanning electron microscopy. Then, 25 freeze-thaw cycles were carried out at the freezing temperature of -10 ℃ to investigate the strength and quality changes of the filling body. The results showed that the compressive strength of the filling material increased with the increase of sulfate concentration in the early stage of hydration, and then decreased. When the sulfate concentration was 6%, the compressive strength value was the largest; at the later stage of hydration, the compressive strength of the filling body decreased continuously, and the erosion rate was positively correlated with the solution concentration. Under the action of freeze-thaw cycles, the strength of the filling body decreases significantly at the early stage of hydration, and the maximum rate of strength loss is 27.2% at the later stage, and the overall mass loss rate is within 3%. The expansion of ice crystals led to the detachment of calcium alumina and C-S-H gels wrapped on the surface of aggregate particles, which cut down the adhesion between the cementation products and destroyed the skeletal structure of the filler. With the increase of hydration age, the hydration reaction consumes a large amount of free water so that the free water content involved in the freeze-thaw cycle is less. Under the erosion environment of sulfate, the aluminosilicate type gel generated by alkali excitation closely laps to fill the internal pores, and the freeze-thaw damage generated in the internal pores of the filler is smaller, which is conducive to improving the freeze-thaw performance of alkali-excited gelling materials.
- 1
Study on the Influence of Openings Considering Fluid-Structure Interaction on the Wind-Resistant Stability of Desulfurization Tower StructureAbstract:
Desulfurization tower structure is a common desulfurization device in many industries such as mining and chemical industry, and its stability is critical. Taking the desulfurization tower structure of a mine as the research object, the study on the wind resistance stability of the desulfurization tower structure under the action of fluid-solid interaction pulsating wind was carried out, and the influence of the opening height, opening angle and opening radius on the wind resistance stability of the desulfurization tower structure was discussed. The results show that different opening parameters have a significant impact on the wind stability of the desulfurization tower structure, and the opening angle has the greatest impact on the wind stability of the structure; When the opening angle is less than 120 °, the wind resistance ultimate bearing capacity of the structure tends to decrease significantly, and when the opening angle is greater than 120 °, the decrease tends to moderate; With the increase of opening height, the ultimate wind bearing capacity of the structure decreases first and then increases; With the increase of the opening radius, the wind resistance ultimate bearing capacity of the structure gradually decreases, basically showing a linear relationship. The research results are of great significance to the design of opening parameters of desulfurization tower structure.
- 1
Coal dust wetting basic characteristics test researchAbstract:
Coal dust is a negative condition caused by mine production. It is necessary to reduce the concentration of coal dust in order to ensure the safety of mine production and workers' health and safety.Through theoretical analysis and experimental test, the effect of different particle size coal dust physical and chemical structure on coal dust wettability was studied in this paper.The physical and chemical characteristics of coal dust with different particle sizes were tested by SEM, surface area and average aperture test and infrared spectrum test, and the contact Angle between coal dust and pure water and the moisture absorption capacity of coal dust were tested, and the microscopic factors affecting the coal dust wetting were obtained.The results show that the smaller the coal dust particle size is, the larger the contact Angle between the coal dust and pure water is, the less the moisture absorption is, and the more difficult the coal dust is to be wettable.The particle size of coal dust decreases, the specific surface area increases, and the total pore volume increases.Oxygen-containing functional groups in coal are reduced, as are hydrophilic groups such as hydroxyl.It is concluded that the specific surface area and total pore volume of coal dust and the content of hydroxyl group are the main factors affecting the coal dust wetting.
- 1
Research on risk assessment and monitoring and early warning of underground ventilation system in phosphate minesAbstract:
In order to achieve safe production of the underground ventilation system in phosphate mines and reduce potential personnel casualties and property losses caused by work accidents, a study was conducted on the risk evaluation model and monitoring and warning system for the underground ventilation system. The two were combined to assist management in making risk decisions. Firstly, key technical indicators were extracted based on the characteristics of the underground ventilation system in phosphate mines and relevant literature, and a linear and general contrast weighted comprehensive scale index mathematical model was introduced to construct a risk evaluation model, which quantitatively identifies the risk level of the underground ventilation system. Secondly, actual production data of the underground ventilation system were collected to verify the rationality and validity of the risk evaluation model. Finally, a monitoring and warning system was developed based on the actual situation of Jiangjiadun Mine to achieve real-time monitoring and timely warning of the ventilation system. During the on-site application of the system, it was stable and reliable, and the operation of the underground ventilation system was good, with a 13.4% decrease in the ratio of warning times. The research results indicate that the application of the risk evaluation model in the monitoring and warning system can improve the risk control ability of safety management personnel.
- 1
Study on the mechanism of rock burst under the loading of thick topsoil in fully mechanized caving face along goaf in deep mineAbstract:
Huge thick overburden loaded rockburst is a unique type of rockburst in Juye mining area. At present, there is no clear theoretical guidance and treatment technology, and the impact manifestation and even accidents still occur from time to time. Based on the engineering background of Zhaolou Coal Mine 7303 working face, this paper studies the mechanism of huge thick overburden loaded rockburst in the fully mechanized top-coal caving face along the deep goaf by means of theoretical analysis and field measurement, and draws the following conclusions: the evolution law of overburden spatial movement structure in the fully mechanized top-coal caving face with thick overburden and thin bedrock is proposed, and the mechanical model of soil pressure arch load transfer mechanism in the overburden loading stage is established, Based on the theoretical analysis results, the scope and grade of the control area in the loading stage of super-thick topsoil in the fully mechanized top-coal caving face along the deep goaf are divided. The mechanism of rockburst loaded by super-thick topsoil in the fully mechanized top-coal caving face along the deep goaf is as follows: when advancing to the breaking step of the overburden bearing layer, the super-thick topsoil transfers its own load to the bearing bedrock through the earth pressure arch, and continues to load into the coal body in front of the working face with the breaking movement of the bedrock, resulting in the continuous increase of the stress in a large range of coal seams in front of the coal wall, which is easy to induce rockburst. Through comprehensive analysis of microseismic monitoring, surface subsidence and field appearance data, it is verified that there is a high correlation between the strata movement, surface subsidence and the occurrence of huge thick overburden-loaded rockburst in the fully mechanized top-coal caving face along the deep goaf, which can be used as an important reference for predicting the huge thick overburden-loaded rockburst.
- 1
An Optimization Study on the Strength of the Backfill in the Jinchuan RoadAbstract:
In order to further improve the strength of the backfill body in the No. 2 mining area of Jinchuan and solve the problem of uneven distribution of the strength of the backfill body, through the determination of the bulk density of the mixture and the optimization test of the filling mix ratio, the influence of cement content, slurry concentration and aggregate ratio on slurry strength was analyzed, and based on the 7D strength requirement of backfill and fluidity requirement of backfill slurry, the influence of cement content, slurry concentration and aggregate ratio on slurry strength was analyzed, the best filling ratio was determined. Through the field industrial test, the comparison analysis shows that the filling cost is reduced by 1.7 yuan/m3 when the best filling mix ratio is adopted, the overall strength of the filling body is increased by 1.1 MPA and 0.39 MPA, respectively The strength variance of the backfill decreased from 1.091 to 0.835, which improved the uneven distribution of the strength of the backfill to some extent. It can be used as a reference to improve the strength of road backfill and solve the problem of uneven distribution of strength.
- 1
Study on heat transfer characteristics and thermal shock factor distribution of sandstone based on one-dimensional heat transfer testAbstract:
In order to explore the heat transfer problem and thermal shock fracture problem of sandstone involved in the development of dry-hot rock, the heat transfer characteristics and thermal stress distribution of sandstone are analyzed in depth by setting one-dimensional heat transfer test and combining with lithology, and the thermal shock factor is introduced to characterize the scope and extent of rock damage. The following results are obtained: one-dimensional heat transfer of sandstone has obvious heterogeneous characteristics, and the stable temperature decreases linearly with the increase of thermal distance, The boiling heat transfer rate is 23.9% higher than that of natural convection without phase change; Based on the analysis of the time and spatial distribution of thermal shock factors, it is considered that the destructive effect of thermal shock on sandstone will go through three stages: high efficiency, low efficiency and ineffective in the direction of increasing thermal distance, and the heterogeneity of thermal shock factors will affect the initiation time and crack propagation morphology of sandstone micro-particles. The research results can provide theoretical reference for the circulation medium heat extraction technology and reservoir fracture reconstruction technology in the development of dry hot rock.
- 1
A Study on Re-concentration of a Cyanide Tailings in Inner Mongolia ProvinceAbstract:
A cyanide tailing pond in Inner Mongolia Province has a total of 1000000 tons with a grade of 0.50 g/t, which accompanied by valuable elements such as Ag, Cu, Pb and Zn. In order to develop secondary resources, a large number of experimental studies have been carried out based on the analysis of the basic properties of samples and in combination with the existing production process. The results indicated that a good beneficiation indicators can be obtained in laboratory, the closed circuit test can obtain a mixed concentrate with a yield of 8.44%, the grades of Au, Ag, Cu, Pb and Zn in the concentrate are 4.34 g/t, 136.62 g/t, 1.33%, 0.65% and 2.39% respectively, the recovery rates were 70.18%,67.80%,79.82%,28.54% and 77.76% respectively, by the existing production of one rough, three sweeping and two refined process flow and without increasing the pretreatment process, with MA+WPS-100 as the collector and 2# oil as the foaming agent. The mineral processing wastewater would not have obvious adverse effects on the environment and production process.
- 1
Study on the Distribution and Evolution Characteristics of Temperature Field in Granite under Directional Thermal ShockAbstract:
In order to explore the feasibility of a new method of thermal directional breaking hard rock roof, in this paper, a self-developed directional thermal conduction temperature control system is used to study the directional thermal shock fracture effect of granite under the action of high temperature heat source, the temperature evolution law of rock under uneven heating and its internal relationship with fracture. The results show that: 1. The temperature rising rate at different positions increases at first and then decreases with time, the failure of granite samples does not occur when the heating rate reaches the peak， and the failure of granite is the result of thermal shock effect and the weakening of rock properties caused by higher temperature. 2. With the increase of thermal shock temperature, the heating rate of the measuring point in the non-heating direction increases, which has an adverse effect on directional thermal shock rock breaking; 3. Under the action of higher temperature heat source, the time of granite fracture is shorter, the relationship between thermal shock temperature and rupture time can be effectively fitted by Allometricl model under experimental conditions. The research results provide a theoretical reference for the in-depth study of the new rock breaking method of thermal directional breaking of hard rock.
- 1
Multi-step prediction of roof pressure of comprehensive mining face based on the improved InformerAbstract:
Roof accidents are very harmful to the normal production of mines and the safety of underground workers, and it is of great significance to realize the accurate and multi-step prediction of roof pressure for the safe and intelligent mining of coal seams. Most of the previous roof pressure predictions were to predict the pressure data of the next moment of the scaffold, focusing on improving the accuracy of single-step prediction, and there was a lack of research on multi-step prediction. Based on the research of multi-step prediction of roof pressure, a new method for predicting roof pressure based on the improved Informer network is proposed, and Savitzky-Golay filter is used to analyze the original pressure, and it is concluded that this method has better effect in predicting roof pressure at multiple future moments. The pressure data of a working face of Fu Village Coal Mine in Zaozhuang City, Shandong Province were selected for experiments, and the results showed that compared with the LSTM and GRU networks, the RMSE error was reduced by 70.18% and 38.31%, and the MAE error was reduced by 73.94% and 40.50%, respectively, based on the multi-step prediction model of roof pressure of the improved Informer network at the second 24 moment.
- 1
Evaluation of the consequences of dam failure in tailings reservoir based on game theory-extendable cloud modelAbstract:
The assessment of the severity of dam failure is an important part of the risk assessment of dam failure in tailings reservoirs. Aiming at the problems of ambiguity and randomness in the evaluation of the severity of consequences, a model for evaluating the consequences of dam failure based on game theory is proposed. Firstly, an index system for evaluating the consequences of dam failure was established and graded. Then, the subjective and objective weights calculated by the optimization sequence relationship analysis (G1) method and the anti-entropy weight (EWM) method were used to obtain the comprehensive weights. Finally, the comprehensive correlation degree is obtained through the extendable cloud model, and the severity level of the consequence is determined. Taking four tailings reservoirs in Hubei Province as examples, this paper substitutes the measured engineering values into the model to evaluate the severity of dam failure, and puts forward feasible suggestions to reduce the severity of dam failure.
- 1
Preparation and properties of all-physical crosslinked Al3+-CMC/MMT-PAM dual-network gelAbstract:
To prevent and control coal spontaneous combustion, Using sodium carboxymethylcellulose (CMC) and polyacrylamide (PAM), Sodium-based (Na-MMT) and aluminum citrate (Alcit) as accessories, By introducing two interactions to construct the structure of the double cross-linking network, Preparation of a fully physical crosslinked Al3+-CMC/MMT-PAM dual-network fire extinguishing gel, The gel strength, thermal stability, viscosity, permeability, and micromorphology were tested, Using the program heating, thermal analysis (TG-DSC), infrared spectroscopy (FT-IR), specific surface area analysis and other experiments to study the fire extinguishing performance of the gel, The results show that the Al3+-CMC/MMT-PAM dual network gel has good thermal stability, MMT concentration of 3%, the best gel strength, No.25 gel permeability of 28.14%. In the gel-treated coal samples, -OH and -C=O content were always lower than raw coal, C-H content was always higher than raw coal, the weight loss rate decreased overall, the total exothermic value decreased significantly, and the specific surface area decreased, indicating that the dual network gel has a certain inhibitory effect on the spontaneous combustion of coal.Fire extinguishing experiment shows that the coal temperature drops rapidly and is not rekindled by adding double network gel.
- 1
Deep high-angle positive fault layered grouting management and inspection technologyAbstract:
Given the attainable threat of water damage caused by high angle positive faults cutting several high aquifers at constant time, we tend to project to seal the faults by suspension injection in layers by "wearing a cap on the head" and "wearing boots on very cheap of the feet". once the treatment was completed, the result of treatment was taken a look at through a water pressure test and downhole drilling, and also the safety of seam recovery was evaluated through numerical simulation, and also the results showed that once the treatment of stratified suspension, the fault doesn"t contain (conduct) water and also the adjacent operating face has safe recovery conditions. At present, the 2 adjacent operating faces higher than and below the seam have safely completed back mining and achieved the management target, which provides a replacement methodology for fault management.
- 1
Study on deformation strength characteristics of sandstone in main shaft of Xiangyun Phosphate Mine under pore water pressureAbstract:
A series of hydro-mechanical coupling tests were carried out on the sandstone in the aquifer of Xiangyun Phosphate Mine, Hubei Province. The influence of confining pressure and pore water pressure on rock deformation and strength characteristics is discussed. The results show that the trend of stress-strain curves of sandstone specimens under the hydro-mechanical coupling is basically the same. The axial strain-stress curves have experienced five stages: compression closure stage, linear elastic stage, stable crack propagation stage, unstable crack development stage and post-peak residual stage. The peak axial strain of the specimen is negatively correlated with the pore water pressure and positively correlated with the confining pressure, while the peak circumferential strain and volumetric strain fluctuate up and down with the increase of pore water pressure. The peak deviator stress, residual deviator stress and initial dilatancy deviator stress of sandstone have a linear positive correlation with pore water pressure, and a negative correlation with confining pressure. The research results show the influence rule and degree of groundwater on the mechanical properties of sandstone of Xiangyun Phosphate Mine , which can provide reference for the stability analysis of sandstone in the mining area.
- 1
Study on Instability and Failure of Roof Pillar Support System in GoafAbstract:
In order to study the instability and failure mechanism of the roof and pillar in the goaf, based on the field investigation of an underground marble mine in Guangdong Province, taking the weakest area of the goaf as the object, the mechanical model of the roof and pillar support system is constructed, and the maximum tensile stress of the roof and pillar support system is derived σmax expression, analyze the influence trend of pillar spacing b, pillar width d, roof thickness h and roof span l on the maximum tensile stress. The results show that under the load of overlying surrounding rock, the weakest area of the goaf is the middle area, the stress is mainly concentrated on the roof, and the form of instability failure is roof tension failure; Keeping other factors unchanged, the pillar spacing of 12.0m is the minimum point of the maximum tensile stress, and the maximum tensile stress decreases first and then increases with the increase of pillar spacing; The pillar width and roof thickness are negatively correlated with the maximum tensile stress. With the increase of pillar width, the maximum tensile stress gradually decreases; With the increase of roof thickness, the maximum tensile stress decreases sharply; The larger the roof span is, the greater the maximum tensile stress is, and the increasing rate remains stable. Combined with numerical simulation and engineering examples, the scientificity and rationality of theoretical calculation are verified, providing theoretical basis for safe mining of such mines.
- 1
Design and Application of Intelligent Irrigation in Ecological Restoration of High and Steep Rock Slope——Taking an abandoned quarry in Shenzhen as an exampleAbstract:
In the ecological restoration of high and steep rock slopes, the biggest problem encountered is often not the restoration construction and plant cultivation, but how to irrigate and maintain after cultivation to ensure the survival of plants and achieve the purpose of ecological restoration. In the engineering practice, the author has designed a new intelligent self-circulation infiltration irrigation system, which well solves the problem of artificial irrigation of high and steep slopes. The system is powered by solar energy, collects surface rainwater and groundwater in the purification area as irrigation water, embeds humidity sensors to control the soil state in real time, and timely feedback it to the intelligent water and electricity control system for overall control, and finally realizes automatic and accurate irrigation through polymer nano-permeability pipes. At the same time, irrigation water is recharged in reverse through infiltration and atmospheric evaporation and rainfall, realizing the recycling of water resources and saving precious water resources. The system uses solar energy system for power supply, no carbon emissions, conforms to the national concept of carbon neutrality, green environmental protection, clean energy conservation. The project example shows that the vegetation coverage rate on the slope reaches 70% in 12 months, and the cost of maintenance and use in 20 years is reduced by about 90% compared with the traditional irrigation method. The ecological restoration effect is good and the economic benefit is significant, which can provide reference for the ecological restoration of high and steep rock slopes in similar abandoned mines.
- 1
Optimization of the position and flow parameters of liquid CO2 injection by buried pipe at the return air side of goafAbstract:
In order to study the location and flow process parameters of liquid CO2 injected by buried pipe at the return air side of goaf, based on the porous media model and gas component transport model, the model of injecting liquid CO2 into the buried pipe at the return air side of 40207 fully mechanized caving face in Xiaozhuang Mine is established, respectively simulated when the depth of the buried pipe on the return air side of the goaf is 50 m, and under different injection positions and different injection flow parameters, changes of O2 concentration in the goaf caused by liquid CO2 injection for 24 h. The results show that: In the range of 20-80 m from the injection position to the working surface, the concentration of O2 in goaf shows a decreasing trend with the increase of the distance between the injection position and the working face, and decreases gradually with the increase of the injection flow; When the injection position is 60 m-80 m away from the working face and the injection flow rate is 500 m3/h-800 m3/h, the effect of CO2 inerting the goaf is good and the concentration of CO2 in the upper corner of the working face will not exceed the limit. The research results show that injecting liquid CO2 into the buried pipe at the return air side can also effectively reduce the O2 concentration in the goaf, thus preventing the spontaneous combustion of residual coal in the goaf, and providing theoretical reference for selecting other injection methods when inerting the goaf with liquid CO2.
- 1
Three-dimensional numerical analysis of the seepage field and stability of the tailings reservoirAbstract:
Most of the instability failure of the tailing reservoir is directly or indirectly related to its seepage characteristics, so the seepage characteristics research has always been one of the hot and difficult problems in the research of tailing reservoir. Therefore, taking a valley-type tailings reservoir as an example, aiming at the complexity of 3D model establishment, the 3D numerical model for the tailings reservoir is firstly established with Rhino and Griddle software. Then, FLAC3D code is adopted to simulate the saturation line of tailings reservoir at normal and flood water levels. It is considered that the saturation line buried depth meets with the standard requirements. However, with the decrease of dry beach length, the saturation line buried depth decreases, which is not conducive to the safety and stability of the tailings reservoir. Then, the fluid-solid coupling theory is adopted to study the stress field, displacement field and stability of the tailings reservoir at normal and flood water levels. The results show that with the rise of water level, the stress and displacement of the tailings reservoir show an increasing trend on the whole. Finally, the strength reduction method is adopted to calculate the stability of the tailings dam at normal and flood water levels, and the corresponding safety factors are 2.914 and 2.69 respectively, namely the rise of the reservoir water level will lead to the reduction of the stability of the tailings dam. The research results can provide useful reference for the safe operation of this tailings reservoir.
- 1
Creep Characteristics and Nonlinear Damage Creep Model of SandstoneAbstract:
The creep property of rock has an important effect on predicting the instability of surrounding rock and ensuring the safety of mine production, in order to solve the problem that the traditional creep model can not reflect the characteristics of accelerated creep stage of rock, an improved Central Highlands model is proposed, to replace the conventional viscous elements in the traditional West protoplast model, the constitutive equations and the 1-d and 3-d creep equations of the improved Central Highlands model are derived. Based on the triaxial creep tests under different stress levels, the parameters of the model are identified and fitted by using Origin software, and the experimental data are compared with the model parameters, the results show that the agreement between the experimental data and the calculated theoretical values is 0.992, and the improved Central Highlands model can accurately describe the characteristics of the accelerated creep stage of rock, which verifies the correctness and applicability of the model, has an important theoretical basis.
- 1
Study on strength characteristics and admixture application of coarse aggregate and high sulfur tailings backfillAbstract:
In order to solve the problems of low strength and late strength deterioration in the filling of fine-grained and high-sulfur tailings in a lead-zinc mine, coarse aggregate and total tailings were used as filling aggregates for filling through the analysis of filling materials, and experimental studies on the ratio and strength characteristics of filling materials were carried out, and CKY filling admixture was developed according to the characteristics of high-sulfur tailings. The results show that when the ratio of total tailings to coarse aggregate is 8:2 and 7:3, the water retention of the filling slurry is better, and the workability of the slurry with mass concentration of 76%~78% is better, and there is no settlement or a small part of tailings settlement, which is suitable for filling. The sulfur content of the tailings is up to 32%, and the test blocks of the backfill show varying degrees of deterioration at 60 and 90 days of age. After the addition of 2% additive, the strength of the backfill body with 8:2 coarse aggregate increases significantly in the front and later stages; the strength of the backfill body with 7:3 coarse aggregate does not increase in the early stage, but increases significantly in the later stages, and there is no strength deterioration. The results showed that the CKY additive was effective in maintaining the strength of the filling body.
- 1
Study on the influence of working parameters on the material particle crushing process of vertical shaft impact crusherAbstract:
In order to improve the crushing effect of vertical shaft impact crusher, this paper uses discrete element software EDEM and fluid analysis software FLUENT to establish the simulation model of vertical shaft impact crusher crushing system and simulate its operation process to study the influence of feed speed and rotational speed on the movement state and collision of material particles in the crusher. Firstly, the influence of working parameters on the velocity of material particles in the crushing chamber is analyzed; secondly, the influence of rotational speed and feed speed on the collision energy and number of collisions of material particles is revealed by using the mesh division method; finally, the relationship between the collision energy and the number of collisions under different working conditions is revealed by establishing the collision energy loss spectrum. The results show that the rotational speed and feed speed have an important influence on the motion state of material particles in the vertical shaft impact crusher. The average collision energy loss of the material particles in the crushing chamber shows a good linear relationship with the rotational speed, and the average collision energy loss decreases with the increase of the feed speed. The collision in the crusher is mostly low energy collision, so the selection of suitable rotating speed and feed speed to reasonably expand the high density collision area and control the number of high energy collision is beneficial to improve the crushing effect of material particles.
- 1
Study on the influence of slag-cotton fiber length and dosage on the strength of fine tailings backfillAbstract:
In order to promote the resource utilization of metallurgical waste and improve the mechanical properties of cement-based backfill with fine tailings, slag cotton fiber was used to modify the strength of the backfill. The effects of fiber length, dosage and curing time on strength were investigated through compression tests, and the mechanism of action of slag cotton fiber was discussed combined with structural damage analysis and microscopic images. The results show that the addition of slag cotton fiber increases the compressive strength of the specimen, and the growth rate is faster when the curing time is 3-14 days, and tends to be stable after 14 days. The effect of fiber length on the strength index is different, and the strength increase percentage of short fiber reinforced specimens is the highest. With the increase of fiber content, the strength index increases first and then decreases, and the maximum strength is reached when the fiber content is 0.6%-0.8%. When the mixing amount is too high, the fibers will intertwine and join to form a clumpy aggregation area, which increases the porosity of the local area inside the filling material and reduces the deformation resistance of the specimen. The bridge effect of slag cotton fiber in the cemented body can inhibit the expansion of compressive fractures and buffer the failure of specimens, thus enhancing the strength performance of fine tailings filling body.
- 1
Application of Chemical Admixtures in the Optimization of Filling Slurry Ratio of Longshou MineAbstract:
In order to reduce the cost of filling materials, on the premise of ensuring the reasonable uniaxial compressive strength of the filling body and the fluidity of the slurry, the optimal mix proportion of admixture added to the filling slurry was studied, and variance analysis was conducted on the experimental results. The experimental results show that when the diffusivity is 91 ± 2cm and the cement sand ratio is 1:4, the concentration of filling slurry can be increased from 78.0% to 83.6% by adding admixture. Under the condition of uniform fluidity, the 7d strength of the filling with 78.0% and 83.6% concentration is 3.94 MPa and 7.04 MPa respectively, and the uniaxial compressive strength of the filling is increased by 77.8%. Therefore, the addition of additives can effectively increase the concentration, improve the uniaxial compressive strength of the filling body, and then reduce the content of cement in the filling material, so as to reduce the filling cost.
- 1
Research And Practice Of Induced Caving Treatment Scheme In Adjacent GoafAbstract:
The existence of goafs in underground mines poses a great threat to mining operations, and it is usually necessary to properly handle them in time. In the early stage of a mine, two horizontal adjacent goafs were left at the level of 2610 m when the stage room method was used for mining. In the later stage, the mine was planned to turn to non-pillar sublevel caving mining. These two goafs need to be treated in advance to ensure the safety of the caving method. Based on the analysis and comparison of the applicability of various schemes, the technical scheme of induced caving treatment of adjacent goaf is proposed, and the caving ability of goaf is calculated. The calculation results show that when the two goafs are connected, the span and area of goaf will reach 100m and 2356m2, which exceeds the critical caving span of 47.71m and the critical caving area of 1789m2.At this time, the goaf will fall. Based on this, the implementation scheme of induced caving with pillar as the starting mining point + reserved ore safety cushion is determined. Subsequently, the numerical simulation method was used to study the induced caving development process and caving law of adjacent goafs. The research results show that the pillar in the goaf is first caved in the induced section. After the two goafs are interconnected, instability occurs and falls upward in an arch shape. With the continuous expansion of the induced section, the goaf has been caving to the surface, and the adjacent goafs have been successfully treated. At the same time, the overburden of the pillarless sublevel caving method is formed. After the field application of the scheme, the dual goals of goaf treatment and overburden formation are successfully realized, which can provide reference for similar mines.
- 1
Remote monitoring technology and application of filling pipeline based on SCADA systemAbstract:
In order to solve the problem of frequent leakage and plugging of coarse aggregate filling, the remote monitoring technology of filling system in Longshou Mine was carried out. Firstly, the main factors and characteristics affecting the accident of filling pipeline were revealed through laboratory tests. The range of leakage and plugging points was determined according to the pressure and flow characteristics and flow changes after single point or multiple point leakage of pipeline. The pipeline fault was identified through statistical analysis and the identified pipeline pressure and flow data were transmitted to SCADA configuration software. The dynamic monitoring and leakage detection of filling pipeline were realized by software analysis. To carry out "half blocking" and "full blocking" experiments, verify the accuracy of SCADA remote monitoring system operation and algorithm judgment, realize remote automatic monitoring and safety management of filling pipeline pressure, flow rate and pipeline wear status, and have important practical significance for promoting the intelligent process of filling system in Longshou Mine.
- 1
Free Surface Mechanical Rock-breaking Method Based on Dynamic Properties of LimestoneAbstract:
The mining of open-pit limestone mines is influenced by many factors such as rock mechanics, safety, and environment. The effects of rock mechanical properties, impact strain rate, and number of free surfaces on the fracture characteristics of hard rocks were investigated using the SHPB(split Hopkinson pressure bar) and on-site tests. It is found that the yield strength of limestone specimens under impact increases with the increase of impact pressure and strain rate, and the energy absorbed by the specimen as a whole and unit volume both show a strong linear correlation with the incident energy. Pre-excavation of the free surface can release the restricted stress in this direction, and increase the number of free surface, which can improve the breakability of the rock in the area to be broken. The improvement method of non-explosive mining of hard limestone was further proposed, and the on-site test proved that the non-explosive mining efficiency could be increased by using hydraulic crushing hammer to break rock after the free surface is pre-cut at the bottom of the working face. The efficiency in the on-site test is increased from 35.9 t/h to 109.58 t/h.
- 1
Study on the Effect of Dynamic Load of Open-pit Blasting on the Stability of Underground FillAbstract:
To determine the effect of open-stage blasting on the stability of the underground fill, the monitoring results were analyzed in terms of mass vibration velocity, vibration transient energy spectrum, and vibration marginal energy spectrum by means of on-site blasting vibration detection. The analysis found that the maximum blasting vibration velocity was 6.38cm/s at one time, which satisfied the safety requirement of blasting vibration velocity for concrete retaining wall of the filling body. In the 5th monitoring +34m platform slope blasting, in the case of a single section of the maximum amount of drug to reduce the peak instantaneous energy of a measurement point instead of the largest, because of the reduction of its burst center distance, to verify the blasting vibration energy is subject to a single section of the maximum detonation charge and burst center distance together. Blast vibration signal in the marginal energy is mainly concentrated in the 0-90Hz, at the same elevation measurement point, with the increase in the burst distance, the marginal energy amplitude decreases, in the middle of the filling body, the blast vibration signal marginal energy amplitude is the largest. This indicates that the medium in the middle of the filler is relatively uniform, and the difference in wave impedance of the internal medium is an important factor affecting the marginal energy amplitude. Finally, through the numerical model of the effect of LS-DYNA slope blasting on the vibration of the underground fill, the vibration velocity of the mass point obtained is 6.73 cm/s, and the results fit well with the blasting monitoring data, which verifies the accuracy of vibration detection in the field.
- 1
Research and Optimization of Performance and Microstructure of Slag-Fly Ash Grouting MaterialAbstract:
Abstract : In order to study the macroscopic properties and microstructure of slag-fly ash grouting material, or-thogonal test and range analysis method were used to test the performance of slag-fly ash grouting material. The effects of water glass modulus, alkali-solid ratio, water-cement ratio, slag-fly ash ratio and other factors on slurry fluidity, apparent viscosity, bleeding rate, gel time, 28d compressive strength and other physical and mechanical properties were studied. The relationship between microstructure and macroscopic properties of grouting materials was analyzed by scanning electron microscopy (SEM). The results show that the water-cement ratio has a signif-icant effect on the physical and mechanical properties of the slurry. The water-cement ratio is positively correlated with the fluidity, gel time and bleeding rate of the slurry, and negatively correlated with the apparent viscosity and compressive strength. The modulus of water glass mainly affects the gel time, and the two are positively correlated. The alkali-solid ratio mainly affects the bleeding rate, and the two are negatively correlated. The ratio of slag to fly ash has a great influence on fluidity and strength. As the ratio increases, the fluidity and strength of the slurry increase. Finally, the optimum scheme of slurry was obtained by matrix analysis: slag: fly ash 7:3, water glass modulus 2.0, alkali-solid ratio 4 %, water-cement ratio 0.9. The slag-fly ash grouting material makes full use of industrial waste slag, and the field engineering application effect is good, which provides reference value for the engineering application and promotion of the material.
- 1
Experimental Study on Covered Karst Collapse under Different Soil Layer StructureAbstract:
In this paper, the karst development area of Hubei Engineering and Construction electromechanical Science and Technology Industrial Park in Siwan Village, Caidian District, Wuhan City, Hubei Province is taken as the research object. Based on site engineering exploration, the physical test equipment is designed by combining the geological environment characteristics and engineering geological data of the study area. By carrying out indoor physical model tests, taking sand and clay at the project site as test soils, the collapse forms of karst collapse under different soil layers were studied, as well as the changes of lateral strain, vertical strain and surface settlement of soil in the middle layer with time during the evolution process. The results show that: (1) The final forms of karst collapse under different soil layer structure are different, showing funnel type, cavity type, straight tube type and so on. (2) The response of soil strain variation is closely related to the fluctuation of water level.The development of karst soil cavity in soil layer can be judged by the strain variation of each measuring point. (3) The influence range of surface subsidence of karst collapse is different in different soil layers. When the clay layer is collapsed, the diameter of the collapse pit is large, but it has little influence on the surface subsidence far from the center of the karst cave. The diameter of the collapse pit in the sand layer is small, but it can affect the surface subsidence far from the center of the karst cave. (4) In the process of collapse evolution, the development of soil cavity in the layer expands upward and horizontally at the same time. According to the surface subsidence and the monitoring data of each measuring point in the layer, it can be concluded that the evolution of karst collapse has experienced three evolution stages: soil loss in the layer, formation and development of soil cavity and surface collapse. The research results have practical significance and reference value for the prevention and control of karst collapse.
- 1
Study On The Mechanism Of High Shear Conditioning To Enhance The Flotation Of Fine Coal SlimeAbstract:
Fine coal slime has the basic characteristics of fine particle size, small mass, and large specific surface area. Traditional flotation shows problems such as low recovery rate and poor selectivity. To solve these problems, a high-shear sawtooth conditioning process was proposed to strengthen the flotation process of fine coal slime, and the influence of the tooth structure parameters of the sawtooth mixer on the flotation effect of coal slime was investigated.. Through the collector dispersion test, collector adsorption test, and coal slime floc particle size test, the mechanism of high-shear conditioning technology to strengthen fine coal slime flotation was explored. The results show that: for the sawtooth mixer, the gap between the sawtooth and the baffle is the key structural parameter affecting the flotation effect, and other structural parameters have little effect on the flotation effect. Under the same operating parameters, high-shear sawtooth conditioning can increase the recovery rate of combustibles by 6.36 percentage points at most, and the ash content of clean coal is generally lower than that of ordinary mixer. With the increase of mixing intensity, the dispersion of collector oil droplets is higher and the adsorption of collector on the surface of coal slime can be effectively improved. In addition, the particle size test of coal slime flocs found that compared with ordinary mixer, the sawtooth mixer has a stronger ability to increase the particle size of coal slime flocs, which effectively increases the flotation particle-bubble collision efficiency.
- 1
Study On The Influence Of Lean Ore Mining On The Stability Of Deep Roadway In JinChuan No. 2 Mining AreaAbstract:
In order to find out the law of deep ground pressure activity caused by the superposition effect of lean ore mining and deep mining in Jinchuan No. 2 Mining Area, a three-dimensional numerical calculation model of shallow and deep combined mining is established. Through simulating mining, the law of ground pressure activity and the characteristics of roadway deformation and instability caused by shallow and deep combined mining are mastered. Through field investigation and monitoring, the change law of stress field and displacement field of surrounding rock of deep stope roadway under lean ore mining conditions is studied, the current deformation and failure mode and stress state of deep roadway are explored, and the impact of lean ore mining above 1250 m on the surrounding rock of deep roadway is predicted. The research shows that the mining of lean ore above 1250 m has a certain impact on the surrounding rock of each section of the deep roadway, and the degree of impact continues to weaken with the increase of the buried depth. The deep roadway has the phenomenon of zonal fracture, and the roadway is mainly subject to roof pressure, and is also subject to deformation and damage caused by oblique compression. The study of roadway stability in the mining process of deep roadway caused by lean ore mining can provide a basis for the safe production of deep roadway in the mine.
- 1
Study on Non-dilution Drawing of Flat Bottom Trench Structure by Caving methodAbstract:
In some non-metallic mines with low ore price, in order to reduce production cost, non-dilution drawing by caving method is often adopted. The selection of stope structure parameters in non-dilution ore drawing determines the ore recovery rate. Therefore, taking a gypsum mine as the engineering background, the flat trench bottom structure was adopted to recover ore. Through the orthogonal test, the influence degree of three parameters, namely the height of caving ore, the trench spacing and the drawing cross spacing, on the ore recovery rate in the flat trench structure was analyzed. The test results show that the ore recovery rate increases with the increase of the caving ore height, and decreases with the increase of trench spacing and drawing cross spacing. The recovery rate of the combined ore with the caving ore height of 30cm, trench spacing of 12cm and drawing cross spacing of 8cm is the highest. SPSS multiple linear regression analysis also shows that the ore recovery rate is maximum when the drawing cross spacing is 8cm and the trench spacing is 12cm. On this basis, the results of the initial test and SPSS multiple linear regression analysis verify that the ore recovery rate increases with the increase of the caving ore height. When caving ore height is greater than 15cm, the adjacent ore drawing ports influence each other in the process of ore drawing, and the influence of ore drawing can be reduced by alternate multiple drawing. The field application effect is good, and the ore recovery rate is 43.49%, which is 13.02 percentage points higher than the original room-and-pillar mining.
- 1
Study on the mining process and stability of downward approach method for medium-thick inclined crushed oreAbstract:
With the development of society, the demand and consumption of non-ferrous metals are increasing, and the mining depth of metal mines will gradually step into the mining range of 1000m-2000m depth. In the face of the extremely broken ore body under high stress, the mining method of downward filling of C material tailings is selected by combining the actual engineering of Jiaojia gold mine site and the principles of mining methodology, and the stability of the downward approach is analyzed in terms of the thickness of the bearing layer, the width of the approach and the height of the approach, and the thickness of the bearing layer, the width of the approach and the height of the approach are selected as h=1.6m, l=1.5m and M=1.4m respectively, and a two-dimensional plane model is established based on the ABAQUS software establishes a two-dimensional plane model to simulate the back mining work under different thickness of artificial false roof when using the downward approach filling method, and obtains the shear stress distribution map of different approaches, plastic zone distribution map and the top plate settlement displacement map when back mining in different approaches to obtain the approach deformation, plastic zone distribution and top plate settlement law, finally, it is recommended to back mining work under 1.0m artificial false roof thickness to ensure safe and efficient mining. It has certain significance for the process selection and stability study of similar mines with downward approach method.
- 1
A Method of Constructing Knowledge Graph of Intelligent Coal Mines Based on Dependency Syntax AnalysisAbstract:
At present, the international mining situation is undergoing a profound revolution, and establishing a green, safe, efficient modern intelligent coal mines development and utilization system is the future development direction. In the studies of intelligent coal mines, the development and updating speed of intelligent technology is fast in recent years, and the applications of cross-integration are extensive. However, it is rarely considered how to sort out existing new knowledge resources to indicate the studies on hot cutting-edge technologies in this field currently, and then achieve the intelligent coal mine that transforms from perceptual intelligence to cognitive intelligence through knowledge engineering construction and knowledge association. To address this issue, this paper proposes a method of constructing a knowledge graph of intelligent coal mines based on dependency syntax analysis. In this method, aiming at the knowledge elements in the field of intelligent coal mines, a dependency syntax analysis way is proposed to extract entities firstly, which is used to address the issue of text extraction; then, according to the structural characteristics of sentences, a dependency syntax tree for extracting knowledge triples is designed, and knowledge triples are extracted from knowledge resources in the field of intelligent coal mines. Finally, the visual modeling of the knowledge graph for intelligent coal mines is achieved. Through experimental analysis and results, the method proposed in this paper can effectively implement the construction and visualization of a knowledge graph in the field of intelligent coal mines.
- 1
Study on secondary mining and stability of goaf of gently inclined medium thick phosphate residual ore resourcesAbstract:
The Ph1 layer of a phosphate mine in Hubei province was mined by comprehensive mining method, and a large number of irregular pillars were left to support the goaf. With the price of phosphate resources rising, in order to dispose of mined-out areas, it is planned to carry out secondary mining of the remaining mineral resources. The paper adopts the method of combining numerical simulation and field engineering test to study the stope stability under three different working conditions and designs the horizontal shallow hole stoping synchronous filling mining method with reserved door pillar. The results show that: (1) Under the condition that the Ph1 mining is completed, the pillar and roof in the northeast direction of the ore section have the risk of tensile fracture; (2) After the secondary mining of residual ore resources, the plastic zone of pillar and roof in mined-out area obviously expands until it is through, and pillar and roof are in an unstable state; (3) The peak value of minimum principal stress decreased significantly at the end of subsequent filling, and subsequent filling played a positive role in improving the stability of goaf; (4) Engineering tests show that the pillar roof displacement can be significantly controlled by the secondary mining method of residual ore resources with "door" pillar, and this mining method can provide guidance for the secondary mining of residual ore resources in similar mines.
- 1
Experimental Study on Mechanics of Cemented Filling Body under Interaction of Different FactorsAbstract:
In view of the problem of poor mass of filling slurry, experimental methods such as compressive strength and SEM EM scanning were used to study the fluidity of filling slurry and filling physical characteristics under different factors. The results show that the mass concentration of ① affects the fluidity of the filling slurry much more than the ash-sand ratio.② The ratio of ash and sand increased from 1:8 to 1:4 and the compressive strength of the filling body increased by 2.4 times, but when the ratio of ash and sand drops to a certain extent, the compressive strength no longer changes significantly.③ When the mass concentration and ash-sand ratio are the same, the amount of waste stone incorporation has a critical value.④ When the mass concentration is the same, the shorter the maintenance age and the lower the gray-sand ratio, the greater the displacement after the filling peak and the maximum increase is 82%; with the increase of age, the hydration products inside the filling body gradually increases, the pore structure gradually decreases, and the density degree gradually increases. The research results are of reference significance for improving the stable carrying capacity of the underground filling body.
- 1
Comprehensive analysis of stability of high and steep slopes in open pit mine drainage field based on numerical simulationAbstract:
Influenced by objective factors such as adverse engineering geological conditions, rainfall and historical disorderly soil discharge, the high and steep slopes of Liwu drainage field of Dabaoshan Mine in Guangdong Province are highly susceptible to safety hazards such as landslides and debris flows. In order to fully guarantee the safe production of the mine, a comprehensive analysis of the stability of the slope of Liwu drainage field was carried out by means of a combination of various numerical analysis methods. The mechanical parameters of the slope were determined through field research and experimental study, the two-dimensional model of the drainage field was numerically simulated by Slide software, the stacking parameters of the unstable slope were optimized, further calculation and verification were carried out by Geostudio and FLAC3D software, the stability state of the drainage field was quantitatively analyzed from multiple angles and the corresponding slope stabilization measures were finally proposed. The results show that the safety coefficient of 3-3 profile does not meet the specification requirements, and the risk of landslide on the slope is higher; the simulation results of FLAC3D, Geostudio and Slide are more consistent, and the analysis method combining multiple simulation means is accurate and reasonable. Finally, according to the simulation results, the management measure of "step-by-step soil discharge and wide platform foot pressure" is proposed, which provides safety guarantee for mining and also provides technical guidance for stability analysis of open pit mine discharge field.
- 1
Numerical Simulation of Damage Evolution of Rock Porous Blasting under Ground StressAbstract:
In order to study the crack propagation mechanism of porous blasting in rock under the action of in-situ stress, the crack propagation and evolution process between holes in rock under different in-situ stress were discussed based on LS-DYNA software, and an optimization scheme was proposed. The results show that the growth and evolution of rock burst cracks can be inhibited under isotropic in-situ stress, and the inhibition effect is enhanced with the increase of stress level. The distribution pattern of the crack is isotropic. The isotropic stress only affects the length of the burst crack, but the propagation direction of the main crack remains unchanged. Under anisotropic stress, the burst cracks tend to evolve along the direction of maximum principal stress. When the direction of rock mass excavation is consistent with the direction of maximum principal stress, the inhibition effect of ground stress is beneficial to protect the reserved rock mass from damage. Reducing the spacing between holes, placing water bags in holes and using high explosive speed and high explosive pressure are all conducive to realizing the penetration of cracks between holes under the action of high ground stress. The proportion of water as the coupling medium varies greatly from 0% to 66%, the range of crushing zone expands by 62%, and the number of cracks increases. From 66% to 100%, the range of crushing zone and the number of cracks did not change significantly. Among them, the latter two methods are beneficial to improve the effect of blasting cracking, and the development of interhole fissure is more complete.
- 1
Experimental Study on Effect of RSM-DF-Based Mixed Water on Mechanical Properties of Filling PasteAbstract:
In order to investigate the influence of the physical and chemical properties of the mixed water on the mechanical properties of the filled paste, the response surface method is used to analyze the experimental results under the interaction of initial temperature, salinity and pH, and the response surface function is obtained for reliability analysis, the mechanism of the effect of mixing water on the mechanical properties of filled paste was studied by SEM (Scanning electron microscope) and XRD (X-ray diffraction).The results show that the optimal level of the three influencing factors is as follows: the initial temperature is 19.923℃, the salinity is 2471.4 mg/l, and the pH value is 5.901;The interaction between initial temperature and salinity had a significant effect on the early strength of paste. SME could observe that the pore structure of paste was loose, the early strength decreased when initial temperature was 30℃and the content of sulfate was 3000 mg/L; The interaction of initial temperature and pH has no obvious effect on the compressive strength of filled paste; The interaction of salinity and pH has a significant effect on the late strength of the filling paste. SME can observe the whole compaction of the filling paste with acid mixed water, however, the pore structure of the paste filled with alkaline mixed water is loose and large cracks are formed. The compressive strength reaches a peak value at 1800 mg/l and pH = 6.5.
- 1
Study on Properties of Cement-based Filling Composites Based on Ultrafine TailingsAbstract:
In order to improve the consumption of ultrafine tailings and reduce the cost of filling, tailing was used to replace part of the cement, and the effects of tailing sand replacement rate, fly ash dosing and metakaolin dosing on the flowability, compressive strength, chloride penetration resistance, sulfate erosion resistance and freeze-thaw resistance of composite filling materials were investigated. The results showed that the slurry flow and compressive strength were negatively correlated with the replacement rate of tailings, and fly ash could improve the slurry flow, weaken the early strength of the filler and improve the later strength development, and the 28 d and 90 d compressive strength reached the maximum value of 8.03 MPa and 8.92 MPa, respectively, when fly ash was mixed with 12%. Metakaolin can accelerate the hydration reaction, thicken the slurry, promote the nucleation of C-S-H gel, improve the internal pore structure of the filler, block the chloride ion transport channel, and improve the mechanical properties and chloride ion penetration resistance of the filler. Under the synergistic effect of sulfate and temperature erosion, the mass and compressive strength of the filler specimens showed a tendency of first increasing and then decreasing. The generation of calcium alumina and gypsum increased the mass and compressive strength of the specimens, but the excessive calcium alumina led to the extrusion and expansion of the structure and the damage deterioration of the filler. With the increase of the number of freeze-thaw cycles, the mass loss rate and strength loss rate of the filling body gradually increased. The low temperature reduced the rate of hydration reaction and the expansion effect of ice crystals, which led to the weakening of the adhesive wrapping effect of hydration products on aggregate particles.
- 1
Research on Gas Desorption Law of Coal Body under Heating InjectionAbstract:
In order to study the gas desorption law of coal under the condition of heat injection and heating, the gas desorption amount at different heat injection temperatures was measured by using the self-designed experimental test system for gas desorption of heat injection coal. The numerical simulation method was used to further study the thermal response law of coal body and the variation characteristics of coal gas pressure under single hole and double hole heat injection modes with heat injection temperatures of 303 K and 333 K respectively. The results show that the variation trend of gas desorption with time shows a sharp rise first and then tends to be stable, and the higher the temperature of hot core injection, the greater the amount of gas desorption, indicating that hot core injection promotes gas desorption. The numerical simulation results show that under the single-hole heat injection mode, a central area with a high temperature centered on the heat injection hole is formed. The effective heating area of the coal body increases with the increase of the heat injection time. The closer to the heat injection hole, the higher the coal body temperature and the greater the gas pressure drop ; comparing the two different single-hole heat injection temperatures of 303 K and 333 K, the heat injection effect of the heat injection temperature of 333 K is more obvious, but the gas pressure in the middle of the heat injection hole and the extraction hole decreases less. Under the double-hole heat injection mode, the elliptical region with high temperature centered on the heat injection hole is formed by the influence of the superposition heat effect of the double-hole high temperature heat injection. When the double-hole heat injection temperature is 333 K, after 50 days of heat injection, the low pressure between the heat injection hole and the extraction hole has a tendency to penetrate, which is more significant than the single-hole heat injection effect.
- 1
Construction Plan and Safety Evaluation of Tunnel Passing Through Water-bearing Goaf in Short DistanceAbstract:
How to pass through the water-bearing goaf in a short distance is a big problem in the process of tunnel construction. Taking the Baiyunshan Tunnel of Chengziyi High-speed Railway as the background, the excavation and support scheme of the tunnel passing through the water-bearing goaf in close distance is introduced, and the numerical model of the Baiyunshan Tunnel and the upper water-bearing goaf area is constructed by FLAC3D finite element software, and the tunnel construction simulation and the analysis of tunnel stability and seepage characteristics at each construction stage were carried out to evaluate the safety of the tunnel. the study shows that in order to ensure that the Baiyun Mountain Tunnel can safely penetrate the water-bearing goaf area at close range, a variety of special construction methods such as advanced geological forecasting, advanced small conduit grouting and grouting reinforcement should be adopted at the same time; The tunnel area has certain construction hazards due to the greater stress and displacement caused by the mining of the upper goaf area, and the reasonable excavation and support means adopted during the construction process can ensure that the displacement, stress and plastic areas of the surrounding rock and lining are at a low level, and the stability of tunnel construction can be guaranteed; The tunnel construction area will be affected by the infiltration of water in the upper close goaf area and there is a hidden danger of water inflow, and the advanced small conduit grouting and goaf grouting reinforcement measures used in the tunnel construction process have good results, the water pressure of the palm surface, grouting ring and lining pore is small, and there is no risk of water inrush in the tunnel.
- 1
Void Structure Evolution Characteristics of Broken Limestone under Compression Based on CT ScanningYang Xiaojun, 李振, 杨鹏, 刘继勇, 王晓东
Abstract:
In order to explore the evolution characteristic of the internal void space during the compression process of broken limestone, CT scanning and reconstruction were carried out for broken limestone under different stress. Three-dimensional void models were established through image optimization processing and 3D reconstruction technology, and the visual quantitative characterization of the internal voids of broken limestone was realized. The research results show that: the particles are re-broken under the effect of stress, and the voids are gradually filled by secondary broken. This results in the reduction of voids the between particles. With the increase of stress, the voids between particles are continuously squeezed and segmented. This leads to an increase in the number of voids in each layer, and the upper layer increases significantly. Stress brings about particle re-breaking and directly affects the evolution characteristics of broken limestone void structure. The whole porosity of skeleton shows a linear decreasing trend with the increase of stress, while the increasing rate of strain decreases gradually until the strain tends to be stable. There are obvious layered evolution characteristics of void structure of broken limestone under compression. Under the same stress, the porosity in descending order is: lower layer, middle layer, upper layer. This means that the closer to the force end, the more obvious the particle re-breaking behavior and porosity reduction.
- 1
Study on Efficient Mining Scheme of Deep Buried Complex Inclined Thin OrebodyAbstract:
A manganese mine belongs to a typical deep buried inclined thin ore body, and the safe and efficient mining of the inclined thin ore body has always been a difficult problem in the industry. The problem of safe production and reaching production has not been solved. The mining technical conditions of a large deep well manganese mine are fully analyzed, and the shortcomings of the current mining technology are summarized. It is concluded that the existing four factors of "deep, thin, inclined and broken" are not conducive to mining, In view of the above adverse factors and in combination with the site conditions and existing engineering conditions, various mining methods are compared and analyzed, and the mining methods suitable for various mining adverse factors of the mine are optimized and adjusted accordingly to obtain the maximum safety and economic effect. It provides engineering practice experience for safe, economic and efficient mining and utilization of complex inclined thin orebody resources with similar large buried depth.
- 1
Investigation on the Influence of Spatial Characteristics on Gas Explosion Overpressure in Coal MinesAbstract:
To understand the influence of roadway space characteristics on gas explosions, the gas explosion CFD code was used to establish full-scale models, and the effect of roadway length and section shape on gas explosion overpressures were studied. The results show that in straight roadways with the same section, the same premixed gas produces the same initial overpressure, and the overpressure attenuation is also the same before approaching the exit. A method is proposed to characterize the aspect ratio deviation of different roadway section shapes. It is found that the squarer the roadway section shape is, the lower the overpressure generated by high intensity explosion. The cross-sectional area and shape of roadway determine the ultimate overpressure. The research shows that reducing the friction coefficient and section constraint of roadway is helpful to weaken the overpressure near the source of gas explosion, thus reducing the disaster intensity.
- 1
Evolution of Thermal Expansion Properties of Limestone under High-Temperature Triaxial StressAbstract:
As a common rock layer in underground engineering, thermal deformation under the action of thermal mechanical coupling of limestone is crucial in high-temperature underground engineering such as deep nuclear waste storage, underground gasification of coal, and geothermal resource development. In this experiment, the evolution of thermal expansion of limestone under high temperature triaxial stress state was investigated by using servo-controlled multifunctional triaxial test system. The experimental results show that the triaxial stress compresses the fracture closure and inhibits the expansion of mineral particles during the real-time warming process under high-temperature triaxial stress, and the microfractures are accompanied by continuous opening and closing competition relationship with the increase of temperature, and the limestone thermal strain curve is step-like, and the thermal strain size and step fluctuation gradually decrease with the increase of hydrostatic pressure. Under the action of thermal mechanical coupling, the inhibition of thermal expansion coefficient is enhanced by triaxial stress at high temperature stage due to thermal cracking and softening of limestone solid skeleton under the action of temperature. There is a threshold pressure for the average coefficient of thermal expansion of limestone during the warming process at 500°C. When the hydrostatic pressure is not less than 25 MPa, the coefficient of thermal expansion decays significantly.
- 1
Research on application of gob-side tunneling technology of narrow coal pillar under stratified miningAbstract:
In the process of slicing mining of thick coal seam, the mining of upper slicing affects the layout of mining gateway on the working face of lower slicing. In order to determine the layout of gateway of lower slice at 110502 working face of Wangwa Coal Mine, the influence of upper slice coal pillar and goaf on lower slice was studied by combining the research method of field investigation, theoretical analysis and field test, and the technical scheme of narrow coal pillar along the goaf in the lower slice gateway was determined. The width of narrow coal pillar and gateway support parameters were designed, and the research results were applied to the driving operation of 110502 (2) tail gateway. The results show that the test gateway surrounding rock has a good control effect, which provides a theoretical and application basis for the follow-up narrow coal pillar goaf excavation in Wangwa Coal Mine.
- 1
Research and Practice on Low-cost Support Method of Broken Surrounding Rock Roadway in Jinchuan No.3 Mining AreaAbstract:
In view of the complex construction technology and high support cost in the support engineering of deep broken surrounding rock roadway in Jinchuan No. 3 mining area, this paper takes the deep broken surrounding rock roadway in Jinchuan No. 3 mining area as the research object. Firstly, the numerical calculation models of double-layer spray anchor net and single layer spray anchor net add steel bar support are established, and the surrounding rock plastic zone, surrounding rock deformation, supporting bolt force and surrounding rock safety area under different support schemes are compared and analyzed. The results show that single layer spray anchor net add steel bar support can achieve the effect of double-layer concreting anchor mesh support. Finally, the field tests of two support modes are carried out in the 1330 sectional layered contact roadway, the deformation monitoring of the support test roadway shows that the roof deformation under the single layer spray anchor net add steel bar support is slightly larger than that of the double-layer shotcrete anchor net, the deformation of the two sides is less than that of the double-layer spray anchor net, and there is no failure in the test roadway. Numerical simulation and field tests show that it is feasible to replace the original double-layer concreting and bolting support with single layer spray anchor net add steel bar support under certain conditions in Jinchuan No. 3 mining area, which can meet the requirements of on-site normal production.
- 1
Design and optimization of local resonant phononic crystal double plate for low and medium frequency sound insulationAbstract:
In order to reduce the medium and low frequency noise of mine axial flow fan, a kind of local resonance phononic crystal double-layer plate was designed, and a sound insulation performance evaluation method was proposed. Based on the evaluation method, the structure parameters of the phononic crystal double-layer plate were optimized by COMSOL Multiphysics software. The results show that the band gap width of phonon crystal veneer decreases with the increase of coating thickness, but increases with the increase of oscillator radius. In the specific frequency band, the sound insulation performance of the designed phononic crystal double layer plate is better than that of the phononic crystal single plate. The sound transmission loss of the phononic crystal double-layer board is 10 dB higher than that of the phononic crystal board in the target noise reduction frequency band (200 Hz~800 Hz) of the axial flow fan, and the STL at the peak noise frequency (500 Hz) reaches the maximum value of 58 dB, and there is no obvious low frequency band of sound insulation, which has a good sound insulation effect.
- 1
Mine Pit Lake ecological restoration abroad: Advances and implicationsAbstract:
The restoration and reuse of mine pit lake left by open-pit mining is one of the important topics for the sustainable development of mining areas. However, China is dominated by underground mining, and the safety management and ecological restoration of this kind of special mining wasteland have not been widely concerned and formed a systematic study. Therefore, based on literature review and inductive analysis, this paper summarizes the types, formation mechanism and characteristics of mine pit lake, and comprehensively combs the research progress and practical model of ecological restoration and reuse of mine pit lake abroad. It is found that the current research mainly focuses on three main aspects: the water balance and water chemistry influence mechanism of the pit lake, the restoration measures and key technologies of the pit lake, the utilization planning of the pit lake and its risk and benefit evaluation, and the time period, dimension and scale involved in the research are constantly expanding; Appropriate reuse of pit lake can play a rich ecosystem service function such as natural adjustment, production supply, entertainment and education. In the future, we should strengthen the systematic survey and value cognition of pit lake resources in China, establish a systematic sustainable restoration planning and design concept based on the whole life cycle, and promote the open pit restoration and mining area revival in China from a multidisciplinary and multidimensional perspective.
- 1
Study on Preparation and Properties of Cement Synergistic Multi - solid Waste Solidified Ferrochrome Slag Filling MaterialAbstract:
In order to solve the problems of large storage area of ferrochrome slag, pollution of soil and water bodies, and low level of resource utilization, a new filling material of quaternary system was prepared by synergistic excitation of slag-lime-desulfurization gypsum-cement clinker to reveal the changes of rheological properties and mechanical properties of the slurry, combined with scanning electron microscopy to elaborate the hydration mechanism of the filling body, and the mechanism of curing/stabilization of the filling material was investigated by toxic leaching test. The results showed that the rheological curves of the slurry conformed to the Hershel-Bulkley model, and the yield stress of the slurry decreased significantly with the increase of superplasticizer dosing, and the dosing of ferrochrome slag was a non-significant factor affecting the change of yield stress of the slurry. The compressive strength of the filling body tends to decrease with the increase of chromium-iron slag doping; the compressive strength tends to rise and then decrease when the water reducing agent dosing increases from 0.1% to 0.4%; the early strength tends to rise and the later strength tends to rise and then decrease when the desulfurization gypsum dosing increases; the compressive strength tends to rise rapidly when the lime dosing increases from 5% to 20%, and The larger the doping amount is, the more obvious the rise is. The compressive strength reached the optimum value when the dosing of ferrochrome slag:slag:lime:desulfurization gypsum:cement:superplasticizer was 30:30:20:8:12:0.3. The microstructural morphology of the filler is dominated by columnar calcium alumina and agglomerated C-S-H gel, both of which are closely bonded to form a strong whole. The toxic ion leaching concentration of the 28-d hydration filler met the requirements of GB 8978-1996 "Integrated Wastewater Discharge Standard", and had significant solidification/stabilization effects on Cr3+ and Cr6+.
- 1
Study on Tailings Flocculation Sedimentation and the Key Parameters of a Thickener based on Image ProcessingAbstract:
Tailings flocculation and sedimentation experiment is the basis of tailings thickening process, and it is also a necessary link to determine the production parameters and equipment selection of thickener. Based on image processing technology, a set of observation and intelligent analysis system for tailings flocculation and sedimentation was independently developed. The system used an industrial camera to collect the experimental images of tailings flocculation and sedimentation. Using gray processing, Gaussian filtering, image segmentation and other methods, the position of solid-liquid separation interface in the process of tailings flocculation and sedimentation can be intelligently identified by measuring the area and coordinate attributes of the region; Taking Dongguashan copper tailings as experimental materials, the tailings flocculation and sedimentation experiment was carried out using this system and the change law of tailings settlement curves was explored. Considering the changes of sedimentation velocity at the separation interface, turbidity of supernatant, static limit sedimentation concentration and solid flux, the optimal process production parameters were determined; According to Kynch settlement theory, the settlement process curves were further analyzed and the settlement parameters were calculated. Based on the actual production capacity of the mine, the key parameters such as thickener diameter and height were intelligently recommended for the mine.
- 1
Numerical Simulation of Nitrogen Injection Technology in Goaf Based on Coupling Relationship Between Spontaneous Combustion and Gas Explosion of Abandoned CoalAbstract:
There is a complex coupling relationship between spontaneous combustion of coal and gas explosion in goaf, which is easy to interlock and affect the safety of coal mine production. Taking 1012 working face of a mine in Wuhai as the research background, it is proposed to inject N2 into goaf to reduce the occurrence of accidents. In order to explore reasonable nitrogen injection schemes, FLUENT simulation technology was used to analyze the distribution of oxygen concentration and gas concentration fields in goaf under different nitrogen injection schemes, and determine the areas of various danger zones. Then, the tunnel engineering safety evaluation method was used to determine the corresponding regional coefficients, and the risk degree scores corresponding to different nitrogen injection schemes were calculated on the basis of the two. origin was used to calculate its coupling function. According to its function, the optimal nitrogen injection scheme was determined that the nitrogen injection amount was 379m3/h, and the nitrogen injection position was located at 58m of the working face. Finally, the engineering field measurement of the scheme proved that its control effect was good. The results show that: In this paper, the oxygen concentration of the goaf oxidation heating zone is used to determine the reasonable nitrogen injection amount of 379m3/h. At this nitrogen injection amount, as the nitrogen injection position moves to the inside of the goaf, the risk degree fraction decreases first and then increases. The optimal nitrogen injection location is determined to be the inside of the goaf inlet wind side 58m away from the working face, and the research results can provide reference for similar projects.
- 1
Optimization of the Roadway Support Process with Non-metallic Anchors and Anchor Mesh ShotcreteAbstract:
In response to the problems of high price, high weight and poor corrosion resistance of metal anchor rods and anchor nets, this paper carries out research on the optimization of non-metallic spray anchor net roadway support process based on theoretical analysis, numerical simulation and field tests in the context of Longshou mine of Jinchuan Group. Preliminary determination of non-metallic anchor rod and anchor mesh specification parameters through calculation of anchor rod and anchor mesh strength index and comprehensive consideration of support effect evaluation index. MIDAS/GTS numerical calculation software was used to construct a two-dimensional numerical model of metal and non-metal (spray) anchor network supported roadway, and to analyze the distribution pattern of the stress (displacement) field of the surrounding rock and the internal force of the anchor rods. On-site support tests were carried out on permanently supported roadways and temporary back-mining approaches to compare and analyse the effect of metallic and non-metallic material support, and to verify the feasibility of the application of non-metallic spray-anchor network support technology in underground mining support projects. The research results can provide reference for the application of non-metallic materials in roadway support.
- 1
STUDY ON COLLABORATIVE TREATMENT OF GOAFS AND PILLAR MINING BASED ON TAILINGS RE-CONCENTRATIONAbstract:
The pillars stability after filling the goafs was simulated，and the results show that the stability have been significantly improved. Firstly，tailings in the old tailings reservoir were mined by excavator，pulped，pumped to the plant and then entered the regrinding process together with the crushed and grinded ores to re-concentate. Then，the existing filling systems was optimized and retrofited by adding the deep cone thickening system and the concrete towing pump for improving the utilization rate of tailings and increasing the filling distance respectively，the full tailings were conveyed to the deep cone thickener，which were then made into the cemented full tailings slurry to fill the goafs of Cai 1# mining area. The top and bottom pillars were mined by ring medium-deep blasthole，the middle pillars were mined by deep blasthole with a cut-raise as blasting space，and the remote scraper was used for ore carrying. The mining rate of pillars was 70% ~80%. Comprehensive utilization of residual mineral resources has achieved remarkable economic benefits.
- 1
Optimization Study on the Undercut Blasting Method of Disposable Blasting Well in Middle-deep HolesAbstract:
In this paper, numerical simulation analysis of two Undercut schemes was carried out using Ansys/LS-DYNA software to ensure the safe and efficient production of the mine. According to the analysis, the final section size of the raise meets the design requirements, and the section of the cavity shows the characteristics of large at both ends and small in the middle, which has a good Undercutting effect; comparing the peak vibration speed at each point shows that the blasting vibration control effect of Option 1 (Nine large holes plus four small holes hollowing method) is significantly better than that of Option 2(nine-hole hollowing method). Option 1 should be used when the offset rate is large and the surrounding rock needs to be protected; Option 2 should be used when the offset rate is small and the surrounding rock does not need to be protected. Both options achieved the expected Undercutting results in the mine field tests. The results of the study provide a reasonable solution for the process of disposable blasting well.
- 1
Study on the dynamic response and energy consumption pattern of fractured sandstone under impact loadingAbstract:
In order to investigate the dynamic mechanical properties and damage mode of rocks containing fissures, as well as the energy dissipation law of the impact crushing process, intact sandstone specimens and five sets of sandstone specimens with different prefabricated fissure angles were selected and dynamic impact tests were carried out using separated Hopkinson compression rods, the test results showed that the fissures would deteriorate the impact resistance of the specimens, with the increase of the fissure angle, the dynamic compressive strength of the fissured specimens was greater, 90° The mechanical properties of the cleaved specimens are closest to those of the intact specimens; the specimens are mainly damaged by tensile splitting and impact crushing, and the different cleavage angles do not affect the final damage of the specimens; as the cleavage angle increases, the ratio of reflected energy to incident energy of the specimens gradually decreases, and the ratio of transmitted energy to incident energy gradually increases, and there is no obvious relationship between the energy dissipation rate and the angle.
- 1
Experimental Study on Mechanical Response and Energy Evolution of Coal under Combined Static and Dynamic LoadingAbstract:
The coal body of coal mining face is often under the combined stress environment of static load and dynamic load impact, and its mechanical response and energy evolution characteristics are closely related to the occurrence of coal mine dynamic disasters. For this reason, the split Hopkinson pressure bar (SHPB) experimental system was used to carry out the impact test of coal under the combined dynamic and static loads, and the mechanical properties and energy evolution laws of coal under different dynamic and static load combinations were analyzed. The results show that: 1) The dynamic strength of coal body has obvious axial compression and strain rate effects. With the increase of the former, it first increases and then decreases, but it is in direct proportion to the latter; 2) Under static and dynamic combined loading, the macroscopic failure mode of coal mass has two types: tensile shear failure and "explosive" crushing failure, and the axial pressure controls the transformation of the macroscopic failure of coal mass from the former to the latter; 3) Dissipated energy of coal can quantitatively characterize the degree of coal fragmentation under combined dynamic and static loading. Fractal dimension of coal fragmentation and dissipated energy show a weak power function growth relationship. This study can provide support for revealing the dynamic instability mechanism of deep coal and rock mass.
- 1
Study on the influence of CO2 under different pressure on coal bursting liabilityAbstract:
The study of coal burst liability plays a key role in exploring the formation mechanism of rock burst during deep underground coal mining. In order to explore the influence of CO2 at different pressures on coal bursting liability, uniaxial compression and cyclic loading and unloading tests with variable upper limit were carried out on coal specimens after CO2 immersion at different forces. The test results show that: The uniaxial compressive strength of coal specimens decreased by 9.97%, 16.14%, 25.02%, 45.97% and 52.77% respectively after being treated with CO2 at pressures of 2 MPa, 4 MPa, 6 MPa, 8 MPa and 10 MPa. The elastic modulus decreased by 11.01%, 18.35%, 27.52% and 44.95%, respectively. With the increase of CO2 soaking pressure, the deterioration degree of mechanical properties of coal samples is gradually aggravated, and the total number of AE cumulative events decreases, which explains the damage mechanism of CO2 to coal body from the micro level. There is a linear relationship between the input energy Unin and the elastic energy Une in the process of cyclic loading and unloading with variable upper limit after CO2 immersion at different pressures. Compared with the original coal specimen, the residual elastic energy index CEF decreased by 9.35%, 17.16%, 25.54%, 47.18% and 55.48%, respectively, after the effect of CO2 at pressures of 2 MPa, 4 MPa, 6 MPa, 8 MPa and 10 MPa, indicating that CO2 has a weakening effect on the coal bursting tendency. When CO2 reaches its supercritical state, the effect on reducing the bursting liability of coal is more obvious.
- 1
Study on Resistance Characteristics of Paste Slurry in Pipeline Transportation Based on Small-scale Loop Pipe TestAbstract:
In order to study the resistance characteristics of paste slurry in pipeline transportation, a set of small-scale loop pipe test device was designed and developed independently, which can be used to carry out loop pipe test of paste slurry under the conditions of different flow velocity, mass concentration and average particle size. The grey correlation method is used to analyze the influence of various factors on pipeline transportation resistance. The results show that the pipeline transportation resistance is the most sensitive to the mass concentration of paste slurry and increases exponentially. The flow velocity of paste slurry has the second greatest effect on pipeline transportation resistance, and the pipeline transportation resistance increases linearly with flow velocity. The average particle size of paste slurry has a dual effect on the pipeline transportation resistance, and the pipeline transportation resistance decreases at first and then increases with the increase of the average particle size. The research results provide theoretical support for the rational design and optimal layout of paste filling conveying system.
- 1
Research on application of equipment for high efficiency thickening and homogenization mixing of ultrafine tailings in a mineAbstract:
In view of the production problems of the original vertical sand silo classification tailings filling system of a gold mine, such as low filling concentration, large amount of slurry flow, low strength of backfill body and insufficient storage capacity of the tailings reservoir, the optimization scheme of vertical sand silo filling system was studied. The -200 mesh ultrafine tailings were used for filling, the efficient flocculation settlement structure of ultrafine tailings and the homogenization mixing system of ultrafine tailings were studied, and the application effect was tested in the field. The results show that: 1) The spiral feed flocculation settlement center cylinder developed for ultrafine tailings can effectively realize the efficient flocculation settlement of ultrafine tailings, the overflow water at the top of the sand silo is clarified, the solid content is less than 200 ppm, and the mineral processing can be carried out directly in the recycling plant; 2) When the concentration of sand at the bottom of the sand silo reaches 60%, the slurry as a whole presents paste characteristics with good fluidity, no segregation occurs, and the bleeding rate decreases significantly; 3) The super-fine tailings slurry and cement are fully mixed in the mixing system, which realizes the efficient utilization of cement, good homogenization effect of filling slurry and high filling quality. By realizing the high quality filling of ultrafine tailings, a solid foundation is laid for the construction process of tailless mine.
- 1
A Meta-analysis of The Research on Miners'' Counterproductive Behavior Based on JD-R ModelAbstract:
In order to improve the safety management level of coal mine and clarify the inducing factors and mechanism of miners'' counterproductive behavior, based on the demand-resources (JD-R) theory and combined with the actual working characteristics of miners, the work demand, work resources, strain factors and motivation factors of miners'' counterproductive behavior were determined from the environment-psychic-behavior level. A complete JD-R model of miners'' counterproductive behavior was constructed, and CMA3.3 was used to conduct meta-analysis on the collected and sorted relevant literature to verify the correctness of the model. The research results show that in the JD-R model of miners'' counterproductive behavior, the work demand and strain factors each contain 4 factors, and the work resource and motivation factors each contain 3 factors, and the interaction effect of each factor is significant. For the health impairment process, work demand positively affects miners'' counterproductive work behavior through the mediating effect of strain factor. In the motivational process, work resources negatively affect miners'' counterproductive behavior through the mediating effect of motivation factors.
- 1
Study on cross-propagation law of porous synchronous perforation fracturingAbstract:
Based on the traditional top-cutting and pressure-relieving goal-side roadway retention technology, it is difficult to control roof deformation and collapse. In order to better master the crack propagation law of roof during top-cutting and pressure-relieving, a scheme of top-cutting and pressure-relieving by directional perforation and simultaneous fracturing was proposed and tested. In the process of traditional fracturing test, perforation spacing and fluid injection flow rate have a great impact on the fracture propagation effect. In this paper, through the true triaxial fracturing seepage simulation test system combined with acoustic emission monitoring system, a 300 mm cubic sandstone specimen was used for simulation test. The results show that: (1) AE event distribution map monitored by AE can well reflect the fracture propagation morphology and fracture propagation law at each stage of the specimen in the fracturing process; (2) The fracture length, initiation pressure and fracture mesh area increase with the increase of transverse perforation spacing, while the fracture width decreases with the increase of transverse perforation spacing. (3) With the increase of liquid injection rate, the secondary fractures produced by the main fracture are less, the fracture migration is also reduced, and the complex fractures become single; (4) In the initial stage of fracturing, the fracture starts from each perforated end. With the progress of fracturing, the fracture at the perforated end becomes complicated, but will expand along the perforated direction to form a transverse perforated through fracture. Finally, the fracture starts from the middle of the specimen surface to extend to both ends. The analysis of the influence of the above factors can provide a certain reference for the design and construction of directional perforating roof cutting pressure relief.
- 1
Visual Analysis Based on CiteSpace for Coal Mine Intelligence Research at Home and AbroadAbstract:
Intelligent coal mine is an effective way to realize the high-quality development of coal industry. With Web of Science and CNKI as data sources, visualization tool CiteSpace and bibliometric methods were used to compare the research progress of Chinese and foreign coal mine intellectualization, mine basic knowledge and research hotspots, and reveal the development trend characteristics. The findings are as below: (1) China has the highest number of publications, accounting for 39.71% of the world's total, which is showing an exponential growth trend. Research has entered the application stage from theory. This field has strong interdisciplinary, and system, computing and computer are the main reference disciplines. Research institutions are diverse and the research did not form a core author group and lacked interdisciplinary and regional cooperation.(2) Big data and cloud computing, Internet of things and sensors, machine learning and artificial intelligence are the main knowledge bases of current coal mine intelligent research. (3) The research on coal mine intellectualization in China and foreign countries embodies the research framework of research method and technology, intelligent control and safety assurance. The difference is that China pays attention to the basic theory and technical architecture, and foreign countries focus on the practical application of specific technology and method.(4) The research hotspots and frontiers are concentrated on “artificial intelligence”, “cloud computing”, “digital twin” and ”coal mine safety” in China.
- 1
Mining Method of Ultra Deep and Ultra Large-scale Sishanling Iron Mine and ConsiderationAbstract:
Ultra deep and ultra large-scale mining is one of the trends of mineral resources development in the future. To provide reference and point out research direction for future production and construction of ultra deep and ultra large-scale mine, the large diameter deep hole stage open stope subsequent back-filling mining method used in the first ultra deep and ultra large-scale mine - Sishanling iron mine is introduced, including the process layout and relevant parameters of development-preparation-cutting-ore extraction, pillar recovery, block ventilation, block back-filling. In view of the problems encountered in the production and construction of Sishanling iron mine, the key problems that need to be paid attention to in the production and construction of the Ultra deep and ultra large-scale mine are put forward from the rock mechanics, including true triaxial rock mechanics, ground pressure monitoring, large-scale blasting of high stress rock mass, simulation of the whole mining process and optimization of mining sequence and parameters. Besides, from the aspect of new technology and method, the future research direction of Ultra deep and ultra large-scale mine is proposed, including TBM+drilling and blasting combined mining technology, power generated by back-filling technology, continuous ore drawing technology, and electric blasting technology for rock breaking.
- 1
Study on creep damage characteristics and constitutive model of aqueous coalAbstract:
In order to obtain the creep law of coal mass around hydraulic cavity with time, the graded uniaxial loading creep experiment of coal samples with different water content was carried out to study the creep law of coal samples with different water content and the damage evolution characteristics of creep mechanical parameters. Then the traditional burgers model was optimized based on water content. The test results show that the instantaneous strain, stable creep and accelerated creep increase with the increase of water content. The instantaneous strain is smaller than the creep strain in the step loading stage. The time and long-term strength of the whole creep process decrease, the failure speed of coal mass increases, and the failure stress threshold of coal mass gradually decreases by 21.4%. Compared with the dry state, the final creep variables of coal samples with water content of 0.89%, 3.54% and 6.26% are 1.23 mm, 1.68 mm and 1.89 mm, respectively, and the increment of creep variables are 10.81%, 50% and 68.75%, respectively. The creep of coal samples with high water content increases greatly. Based on the influence of water content on creep parameters, Traditional burgers model can describe decay creep and constant velocity creep, but it lacks the description of accelerated creep, and the series-parallel creep model lacks the description of nonlinear creep process.elastic elements under water damage and a nonlinear time-variable viscous element are introduced. Levenberg-Marquardt optimization algorithm is used to identify and inverse the parameters of the creep constitutive model of water damage. The theoretical creep model is in good agreement with the experimental results. It can describe the creep failure law of coal after water.
- 1
Stress Analysis and Activation Law of Normal Fault Layer with Large DropAbstract:
Based on the problem that the roadway surrounding rock is easily broken by the large drop fault, and the activation phenomenon occurs after being affected by the dynamic pressure of mining, which is not conducive to the safe production of the mine, the FLAC3D secondary development technology is used to optimize the fault simulation method. The stress influence area near the fault, the damage degree of coal and rock mass, and the fault activation criteria are studied, and the stress distribution and activation law of the large drop normal fault are revealed. The results show that when the coal seam is located at the footwall of a large fault, the stress rises sharply after passing the fault and reaches the peak position in a short distance; When it is located in the hanging wall, the stress concentration phenomenon occurs in the footwall. When it is within a certain range from the fault, the stress rises sharply to the peak position, and gradually tends to be flat after passing the fault; The larger the fault drop is, the larger the influence range of stress is; The greater the burial depth is, the higher the fault stress concentration is, and the larger the damage range to coal and rock mass is. The research results not only expand the application scope of the simulation software, but also provide an important basis for the setting of the protective coal pillar of the large drop fault.
- 1
Study on Transient Stability of Mountain Slope Under in Situ Leaching Environment of Rare Earth OreAbstract:
In order to reveal the transient stability change rule of mountain slope in different periods of top water and leaching solution, based on the coupling effect of SEEP/W and SLOPE/W calculation modules in Geo Studio software, the transient stability of rare earth mine SLOPE under the conditions of self-weight+groundwater+liquid injection was studied. The transient stability of in situ leaching of rare earth ores in three stages, namely, no liquid injection, liquid injection and top water, was obtained. The results show that: (1) the rare earth mine slope is stable under the condition of no liquid injection (natural). Under the condition of top water and leaching solution injection, the slope is unstable. (2) For the slope with steep local maximum gradient (40° or more), landslide is easy to occur in the stage of liquid injection and top water of rare earth ore leaching. (3) Reducing the proportion of liquid injection or stopping liquid injection can basically ensure the stability of the slope. Through software simulation, the feasibility of the measure is verified.
- 1
Study on Dissolution-Precipitation Law and Permeability Evolution Law of Datong Basalt under Long-term CO2 SequestrationAbstract:
The impact of CO2 emission on the environment is increasing day by day, so it is urgent to study CO2 emission reduction and sequestration. As a new way of CO2 sequestration, divalent metal cations such as calcium, iron and magnesium in basalt react with CO2 dissolved in water, and CO2 is converted into stable compounds such as CaCO3, MgCO3 and FeCO3, which are sealed in basalt strata. In this paper, the basalt of "Datong Volcano Group" is taken as the research object, and soaked in CO2 aqueous solution at 50℃ and 8MPa for 86 days. The results show that the quality of basalt will decrease with the prolonging of storage time, and its decreasing rate will gradually decrease, accompanied by the formation of precipitation with a certain quality, and its forming rate will gradually decrease with the prolonging of storage time. The porosity of basalt increases with the storage time, and the increasing rate decreases with the storage time. Based on the evaluation of theoretical storage capacity and the experimental results, it can be concluded that the basalt formation in Datong, Shanxi Province has great carbon dioxide storage potential.
- 1
Influence of Hole Parameters on Stability of Desulfurization Tower under Axial CompressionAbstract:
In the process of mining and processing of a series of minerals represented by pyrite, a large number of harmful gases such as sulfur dioxide will be generated when sulfide contacts with air. In order to analyze the influence of opening parameters on the stability of the tower, the buckling performance of the structure of the desulfurization tower with different opening parameters under axial compression is studied by numerical method. The influence of opening height, size, opening Angle when multiple holes are opened and external round pipe is analyzed on the stability of tower structure. The results show that the very small opening will significantly reduce the stability of the structure. The bearing capacity of the structure is lower when the opening is near the axial compression end, and the maximum deformation usually occurs at the opening. When the proportion factor is greater than 0.3, the stability of the structure is almost completely destroyed. In the case of double openings, the bearing capacity of the structure is the best when the included Angle is 0 degrees, and the worst when the included Angle is 45 degrees. In this case, the external circular pipe can increase the bearing capacity of the structure by 7 times.
- 1
Study on Development Law of Advance Plastic Zone in Mining Roadway and Support OptimizationAbstract:
In order to effectively solve the large deformation of deep coal roadway after working face mining, the 3213 material roadway of a mine is taken as the engineering background. Based on the analysis of the roof and floor rock properties of 3213 material roadway, the deformation characteristics of roadway affected by mining, and the original support method has been unable to continue to maintain the stability of roadway surrounding rock. Using the method of numerical simulation and theoretical analysis, through the study of the new space-time development law formed by the mining of the plastic zone, the concept of "" strengthening the top and bottom angle-strengthening the coal wall "" is put forward, and the rationality and practicability of the combined support method of "" strengthening the top and bottom angle-strengthening the coal wall "" is verified by FLAC3D software combined with field engineering measurement. The results show that after the 3213 material roadway is supported by the combined support method of "" strengthening the top and bottom angle-strengthening the coal wall "", the control ability of the surrounding rock of the roadway is increased by 80 % compared with the original support, which can provide reference for other similar roadway support projects.
- 1
Study on reinforced structural system of buildings in the impact area of Fushun West open-pit MineAbstract:
,After nearly a century of mining at the Fushun West Open Pit, the surrounding urban strata have been affected by multiple chain hazards such as landslides, ground cracks and mudslides, and irreversible damage to buildings has occurred. Although the slope treatment project of the west open pit mine has been basically completed in recent years, there is still a risk of further penetration of damage to the damaged buildings under the influence of the weak deformation of the present ground surface, and it is of great practical significance to propose a practical system of structural reinforcement methods for buildings. To this end, the distribution characteristics of the prior geological hazards of the West Open Pit Mine and the surface deformation pattern of the affected area before and after the treatment were systematically analyzed, and the breakage characteristics and damage level areas of the surrounding buildings were divided. In view of this, a method system combining rigid anti-deformation reinforcement and flexible absorption of deformation in buildings is proposed, and numerical simulations of the overall building model and the model of key load-bearing members are carried out. The results show that the structural reinforcement system of the building can effectively improve the effectiveness of the building in resisting, absorbing, and transforming the effects of ground deformation, and fully optimize the overall resistance of the building to damage. This will provide technical support and reference basis for the stability and safety reinforcement works of urban buildings around the open pit mine in China.
- 1
Pre-Set Concrete Wall Formation in Coal Tunnel and Surrounding Rock Control TechnologyAbstract:
In order to solve the problem of mine gas emission and improve the coal resource recovery rate, the problem of leaving coal pillars between the return air lane and gas lane of 309 comprehensive mining working face of Daning coal mine as the engineering background, and the technology of pre-setting concrete wall in coal lane to form a lane is proposed and its construction process is analyzed, that is, when arranging the return air lane, the lane is dug in a wide face and permanently supported by anchor rods (ropes), and the dug in working face is delayed by 50 m, and the concrete wall is poured in the The concrete wall is poured in the roadway to isolate the roadway into a double roadway, and as the working face is retrieved, the top plate collapses along the top cutting line to form a roadway along the empty roadway. The stability of the isolation wall was analyzed through theoretical calculations, and the wall width of 1.6 m met the safety requirements for support. According to the designed roadway support parameters, the numerical simulation analysis is carried out, and the combined support scheme of "separation wall+anchor bolt+anchor cable+reinforcement beam+anchor mesh" is finally determined for the roadway.This technology can provide a reference for similar mines to implement the technology of pre-set concrete wall in the roadway.
- 1
Stability Analysis of Mining Disturbance to Protecting Coal Pillar in High Stress Thick Coal SeamAbstract:
Aiming at the influence of gob-side entry driving and mining disturbance of working face on the stability of coal pillar in head-on roadway protection in high stress thick coal seam, taking 1305 working face of Zhaoxian Coal Mine in Jinyuan, Shaanxi Province as the engineering background, through theoretical analysis, numerical simulation and field practice, the stress evolution in coal pillar and the breaking law of basic roof during mining and excavation are analyzed. The mechanical model after the first and second breaking of basic roof is given, and the stress and elastic-plastic zone distribution law of coal pillar in head-on roadway protection within 40 m before working face during mining and excavation are analyzed. The results show that the triangular block structure formed by the basic roof breaking caused by the mining of the working face is an important factor causing the instability of the coal pillar. During the excavation of the air roadway, the stress concentration area and the peak stress are mainly distributed in the side coal pillar of the goaf, and the side coal pillar of the roadway is basically stable. During the mining period of 1305 working face, the stress superposition of coal pillars in the range of 20 m in front of the working face is obvious and the width of plastic zone increases greatly. The stress distribution law of coal pillars at 30 m and 40 m is similar to that during roadway excavation, and the width of plastic zone increases little. In summary, the mining of working face has a serious impact on the stability of 20 m coal pillars in front of the working face. Field practice has proved that reasonable support parameter design can effectively control the surrounding rock of roadway.
- 1
Test Study on Influencing Factors of Anti-Erosion Properties of Tailing Sand Improved by ClayAbstract:
In order to analyze the anti-erosion properties and influencing factors of tailing sand improved by clay, the rainfall slope erosion test in the laboratory was carried out to study the effects of slope gradient ratio, clay content, rainfall intensity and dry-wet cycle times on the slope runoff, sediment erosion, runoff and mud content per unit time of tailing sand improved by clay. The test results show that the anti-erosion properties of tailing sand improved by clay are greatly affected by slope degree and rainfall intensity, runoff and sediment erosion increase linearly with slope ratio and rainfall intensity. When the clay content in tailings sand is 30%, the anti-erosion properties is better. After the first dry-wet cycle, the erosion damage of tailing sand improved by clay slope is more serious, and the mud content fluctuates significantly in 30 min. Compared with the total erosion amount of the first erosion sediment, the total erosion amount is reduced by 30% when the dry-wet cycle is 3 times. The dry-wet cycle restrain the erosion damage of rainfall on the slope of tailing sand improved by clay. The research results can provide a reference for the analysis of anti-erosion properties of tailing sand improved by clay.
- 1
The Influence of Secure-Base Leadership on the Safety Behavior of New Generation Miners: A Cross-Level ResearchAbstract:
In order to effectively improve the safety behavior of the new generation of miners, on the basis of social exchange theory, social information processing theory and self-determination theory, this paper introduces safety climate at the organizational level and thriving at work at the individual level as mediating variables, and discusses the internal mechanism of secure-base leadership on the safety behavior of the new generation of miners. By collecting paired data of 296 first-line miners in two time periods, SPSS24.0, AMOS23.0 and HLM7.0 were used for empirical test. The results show that the secure-base leadership positively predicts the safety behavior of the new generation of miners across levels; secure-base leadership positively affects the safety behavior of the new generation of miners through the independent mediating role of safety climate and thriving at work and the chain mediating role of safety climate and thriving at work.
- 1
Spatial and Temporal Distribution Characteristics of Aerosols in Mining Areas Based on Ecological Restoration: The Case of Qian"an Mining AreaAbstract:
In this paper, the aerosol products MCD19A2 and MOD04_3K from MODIS were used to explore the spatial and temporal variability characteristics of aerosol optical thickness, ?ngstr?m index and aerosol type during 2015-2020, using the Qianan mining area as the study area. The results show that (1) compared with 2015, the AOD values are significantly lower in 2020, except for the winter AOD in 2020. (2) Compared with 2015, the proportion of fine particles increased in the northwest and the proportion of coarse particles increased in the southeast in 2020. The AE index of the mine also has obvious seasonal characteristics, with a smaller AE index in spring, where pollutants are mainly coarse particulate pollutants, and a larger AE index in summer and autumn, where air pollutants are mainly fine particulate matter; (3) the seasonal changes of the AE index also have obvious spatial and temporal distribution characteristics. Compared with 2015, the AE index in the eastern part of the winter decreased significantly and the proportion of coarse particles increased; in the spring, the overall AE index in the region increased and the proportion of coarse particles decreased; in the autumn, the AE index in the north increased significantly and the proportion of coarse particles decreased. Summer is the peak period of AOD and AE index throughout the year, which is probably due to the large amount of fine aerosol particles produced by straw burning in June and July. (4) The mine area is mainly composed of biomass burning or urban-industrial type aerosol and mixed type aerosol; compared with 2015, the main aerosol type changed significantly in spring 2020, and the proportion of dust type aerosol was significantly reduced. From the above study results, it is clear that the ecological restoration project in the mine area from 2015 to 2020 has obviously changed the optical properties and types of atmospheric aerosols in the mine area, and improved the atmospheric pollution in the Qian"an mine area to some extent.
- 1
Study on the relationship between wave velocity and mechanical properties of overlying rock in Shendong Mining AreaAbstract:
The compressive strength and longitudinal wave velocity of rock is an important index to evaluate the strength, stability and surrounding rock classification of rock mass. In order to study the relationship between the wave velocity and the mechanics properties of rock in Shendong mining area.We use overburden rock in Daliuta coal mine as the research object. First, we test the longitudinal wave velocity, and then use RMT-150C mechanical testing machine on the uniaxial compression test and indirect tensile test, the results include uniaxial compressive strength, tensile strength, elastic modulus, wave velocity, Poisson's ratio and other physical and mechanical parameters. Finally, the relationship between longitudinal wave velocity and mechanical parameters of different kinds of rocks is discussed. The results confirm obvious linear correlation between longitudinal wave velocity and the compressive strength, tensile strength, elastic modulus of rock.
- 1
Study on the Migration Law of Direct Covered Sandstone in Layered Mining of Thick Coal SeamAbstract:
In order to analyze the movement law of the roof slate layer of the straight cover sandstone after the layered mining of the thick coal seam, the working surface on the 13121 mining area of the coal group A of Gubei Mine was used as the engineering background, and the overlying rock movement of the thick coal layer of the Gubei Mine was studied by combining physical similarity test and theoretical analysis. By constructing the structural mechanical model of layered mining overgrowth, the calculation formula of overburden load is obtained. The results show that the direct top collapse step distance is 85m; The solid coal at 18~20m in front of the work is at the peak of the supporting pressure, and the peak range of the lower stratification stress is 19.07~23.35MPa, and the peak range of the lower stratification stress is 17.98~20.98MPa, respectively; The damage of the 11.6m thick sandstone layer and its lower rock layer loses the bearing capacity of the overlying rock layer, resulting in the stress peak of the upper stratification being greater than that of the lower stratification; The height of the upper stratified fracture zone is 32 m, the height of the collapse zone is 17 m, the height of the lower stratified fracture zone is 40 m, and the height of the collapse zone is 23 m, and the lower stratified collapse range develops more than the upper stratified zone. It provides certain guiding significance for the layered mining of Gubei Mine.
- 1
Analysis of mechanical properties and failure mode of fractured rock under dry wet cycleAbstract:
In order to study the influence of the number of cracks (0, 1, 2 and 3) on the mechanical properties and failure mode of sandstone under the condition of acid dry wet cycle, the samples were immersed in solutions with pH values of 2.0, 4.5 and 7.0 for 0, 1, 3 and 5 times and then subjected to uniaxial compression tests. The results show that the peak strength and elastic modulus of the specimens immersed in different pH solutions gradually decrease with the increase of the number of dry wet cycles and the number of cracks, and the deterioration of the damage caused by it aggravates the corrosion damage of the specimens immersed in chemical solutions; At pH 7.0, macro cracks induce the development of cracks in sandstone failure, and with the increase of the number of cracks, the failure mode of sandstone changes from shear failure to tension shear failure.
- 1
Effect of Ca2+ Concentration on the Adsorption Behavior of Nanoparticle Collector on Mineral SurfaceAbstract:
The flotation effect of traditional non-polar hydrocarbon oil collector to recover difficult-to-float coal such as low-rank coal and oxidized coal is often very poor. To achieve efficient recovery and utilization of difficult-to-float coal, it is urgent to develop new and efficient flotation agents. Nanoparticle flotation collector technology has received wide attention in the field of mineral processing. The various ions dissolved in the slurry have a significant effect on the interaction between the collector and the mineral surface. In this paper, cationic polystyrene (PS) nanoparticles prepared by emulsion polymerization were used as coal flotation collectors, and the effects of Ca2+ ion concentration on the in-situ adsorption and desorption processes, adsorption layer conformation changes, and adsorption kinetics of polystyrene particles on amorphous carbon chips (coal model) and SiO2 chips (quartz mineral model) were analyzed by dissipative quartz microcrystal balance (QCM-D) technique, respectively. The results show that the hydrophobic polystyrene nanoparticles adsorb on the surface of both amorphous carbon and SiO2 chips in different environments, and the adsorption is irreversible, which confirms that PS nanoparticles can be used as a coal flotation collector. The adsorption of PS particles on the surface of both amorphous carbon and SiO2 chips gradually decreases with the increase of Ca2+ ion concentration, and the adsorption process is more consistent with the quasi-level kinetic model. This study can provide some theoretical basis for the adsorption behavior of PS nanoparticles in coal flotation.
- 1
Improved Sparrow Search Algorithm to Optimize SVR Combined with FLAC3D to Predict Mining Surface SubsidenceAbstract:
Accurate prediction of the surface subsidence caused by underground mining has always been a difficult problem for the safe development of mines. In order to improve the accuracy of the prediction of the maximum surface subsidence in the goaf, the methods of machine learning and numerical simulation were used to make a comparative study of the surface subsidence in the goaf of a phosphate mine. Considering the influencing factors of the maximum surface subsidence and referring to the statistical results of the relevant data of domestic mines in the literature, exploratory factor analysis (EFA) is used to reduce the dimensions of the influencing factors, and the support vector regression model (EFA tSSA SVR) optimized by sparrow search algorithm (tSSA) based on t distribution and tangent flight mechanism is trained, This model and FLAC3D numerical simulation model are used to predict the surface subsidence caused by underground mining of a phosphate mine. The results show that the prediction results of the two models for the maximum subsidence after one step of mining are similar, and compared with the actual subsidence after one step of mining, the relative error of the maximum subsidence predicted by FLAC3D is three times that of EFA-tSSA-SVR model, indicating that EFA-tSSA-SVR model has a good prediction result. Finally, EFA-tSSA-SVR model is used to predict the second, third The maximum surface subsidence after four steps of mining is 22.3 cm, 24.1 cm and 25.9 cm. This model can provide a certain reference value for the prediction of mining subsidence.
- 1
Effect of Water Content on Dynamic Strength and Deformation of Red Sandstone Under Impact LoadAbstract:
During the blasting and excavation of underground engineering rock mass, dynamic load and groundwater have a significant impact on the safety and stability of the engineering rock mass. In order to reveal the effect characteristics of dynamic load and moisture content on rocks, the improved Hopkinson pressure bar test device is used to conduct impact compression test on red sandstone under six moisture content conditions with different impact velocities in 4. According to the three sets of stress wave signals collected in the test, the dynamic stress-strain curve of the rock is transformed by a three-wave method, and the dynamic peak stress, extreme strain and average strain rate of rocks are obtained. The experimental results show that under the same dynamic load, as the moisture content increases, the dynamic peak stress progressively diminish, and there is a good exponential function between the two. The dynamic extreme strain of the rock increases linearly with increasing water content. The average strain rate of the rock increases exponentially with increasing water content. As the impact velocity increases, the dynamic peak stress, the dynamic extreme strain, and the average strain rate of the rock all increase. The research results can further promote the development and improvement of rock dynamics theory, and also help monitor the stability of deep rocks, providing a certain reference for efficient blasting excavation.
- 1
Experimental Study On Resistivity Response Characteristics of Rainfall Slope DamageAbstract:
In order to study the damage and destruction of dump slope under rainfall, a physical model of rainfall slope was designed and made.Based on the three-phase medium theory of rock and soil mass and Maxwell's conductivity formula, the change of damage resistivity of rainfall slope is generalized, and the relationship expression of damage and resistivity and porosity of rainfall slope is derived considering both macro and micro changes.The rationality of the model is verified by comparison with Archie formula.High-density resistivity method is used to measure the apparent resistivity of slope rock and soil at different rainfall times, and the formation process of internal damage of rainfall slope is inversed. The change of apparent resistivity of slope with different water content is compared, and the change characteristics of apparent resistivity of weak surface and crack development of rainfall slope are analyzed based on the resistivity theory of rock and soil mass.The test results show that the rock and soil mass of rainfall slope is a dynamic cyclic process from unsaturated to saturated.The apparent resistivity is negatively correlated with the water content in the pores and fractures in the slope. The apparent resistivity decreases during water infiltration and increases during crack development. In the process of slope damage, the apparent resistivity changes under the coupling effect of crack development and water seepage, and the apparent resistivity of the adjacent area of the original "defect" point abrupt changes and fluctuates.The abrupt change usually occurs after the slope is saturated in the area adjacent to the "defect" point.The damage in the slope can be judged according to the abrupt change and abnormal fluctuation of the apparent resistivity detected.
- 1
Study on Setting and Hardening Performance of Cement-based Filling Materials Regulated by Polyacrylonitrile FiberAbstract:
In order to ensure that the polyacrylonitrile fiber-regulated cement-based composite filling slurry meets the requirements of deep mine pipeline, orthogonal tests were established to investigate the effects of fiber dosing, fiber length, exciter dosing and phosphogypsum dosing on the setting time, consistency, delamination, water secretion rate and rheological properties of the filling slurry. The results showed that with the increase of exciter dosing, the setting time and the mixing properties of the slurry tended to decrease first and then increase, and phosphogypsum had a significant slow setting effect on the composite filling slurry. The rheological curve of fiber-doped composite filling slurry is in accordance with the Hershel-Bulkley model, and the fiber consumes the free water and hydration products of the gelling system. The fiber consumes the free water and hydration products of the gelling system, increases the collision contact area between the solid phase particles, increases the viscous force and friction between the hydration products, and increases the yield stress and viscosity of the slurry
- 1
Research on the Influence of Unloading Rate on Mechanical Behavior and Energy Evolution of Sandstone under True Triaxial ConditionsAbstract:
The true triaxial loading and unloading test of sandstone was carried out by the true triaxial fluid-structure interaction test system, and the influence of different minimum principal stress directions unloading rate on its mechanical behavior and energy evolution characteristics was studied. The test results show that with the increase of unloading rate, the maximum volume compression decreases, and the maximum principal strain required to reach the maximum compression also decreases. The increase of the unloading rate increases the intermediate principal stress coefficient of the rock sample, and the hydrostatic pressure and shear stress decrease. With the increase of the unloading rate, the total energy at the peak decreases, the elastic energy shows a trend of increasing first and then leveling off, and the dissipated energy decreases. The stage before the start of the test to the maximum compression point is divided into phase I., and the stage after the maximum compression point to the peak is divided into phase II. With the increase of unloading rate, the increase of dissipative energy conversion rate in stage I was low, and the deformation of rock samples was mainly elastic. In stage II, the conversion rate of dissipative energy increased to a high extent, and the deformation of the rock sample was mainly plastic. The above research is of great significance for controlling rock deformation and failure.
- 1
Effect Analysis of PAM with Different Ionic Types on Flocculent Settling of Coal Gasification Fine SlagAbstract:
The influence of three ionic types polyacrylamide (PAM) on the flocculent settling of coal gasification fine slag was studied with the average sedimentation velocity and turbidity of supernatant as the macroscopic evaluation indexes. The results show that anionic polyacrylamide has the best flocculent settling effect on coal gasification fine slag. Compared with the condition without additive, the sedimentation velocity increases from 18.9 to 83.2cm/min and the turbidity of supernatant decreases from 90.3NTU to 14.7NTU when the dosage is 60g/t. With the help of high-definition particle image analyzer, spectrophotometer and infrared spectrometer, the changes of floc morphology, amount of adsorption and functional groups before and after the reaction of PAM were analyzed. It can be seen from the test analysis that the adsorption capacity of anionic polyacrylamide on the coal gasification fine slag is the largest, the formation of the largest and dense flocs, which is the main reason for the good flocculation settlement effect. The results provide the basis for the selection of flocculant for the flocculation settlement of coal gasification fine slag.
- 1
The effect of Metal Cations on the Settling behavior of Kaolinite ParticlesAbstract:
Kaolinite is the main mineral in highly argillated slime water, It has the characteristics of fine particle size, easy argillation, surface charge and so on. It maintains stable dispersion in slime water for a long time, which is not conducive to the rapid settlement of slime water. In this paper, the effects of common metal ions Na+, K+, Mg2+, Ca2+, Al3+ on the settling characteristics of kaolinite particles were studied, and the action mechanism of metal ions in the process of kaolinite settlement was revealed by means of Zeta potential, Fourier transform infrared spectroscopy, microcalorimetry, contact angle and laser particle analyzer. The results show that under natural pH conditions, the comprehensive settlement index is the best after adding Al3+, and the settlement effect is better, followed by Ca2+and Mg2+, and the effect of K+ and Na+ is relatively poor. The mechanism analysis shows that: (i) the addition of metal cations can reduce the absolute value of Zeta potential on kaolinite surface, compress the double electric layer and promote the coagulation and settlement of kaolinite particles; (ii) metal cations can react with the hydrophilic hydroxyl functional groups on the surface of kaolinite, inhibiting the hydration of kaolinite, and thus strengthening the surface hydrophobicity, which is conducive to the hydrophobic agglomeration and settlement of kaolinite particles.
- 1
Research and application of thick hard roof blasting roof cutting protection district dip roadway technology in stopping line of fully mechanized caving faceAbstract:
The thick and hard sandstone layer of 13030 fully mechanized caving face in Hengtai Coal Mine is 23.9 m, the value of Platts coefficient f up to 10.8~14.3, entering the end mining stage, surrounding rock of district dip roadway in mining area will be seriously deformed and destroyed by mining. In order to solve this problem, study on blasting roof cutting pre-splitting roof technology of advance working face stop line. Using theoretical analysis and numerical simulation methods, the optimal roof cutting height is 25.4 m and the optimal roof cutting angle is 75 °; based on field test, the optimal blast hole spacing is determined to be 2400 mm, and the charge structure is segmented uniform charge. Compared with the condition without roof cutting, the peak value of the advanced support stress in the roof cutting face of the stop line is reduced by 23%, it can effectively improve the stress environment of downhill roadway. The field industrial test results show that the roadway deformation tends to be stable after 25 days of stop mining, the maximum displacement of the two sides is 340 mm, and the maximum displacement of the roof and floor is 380 mm, after repair and reinforcement can serve the next working face, the surrounding rock control is favorable.
- 1
Stability Analysis of Surrounding Rock of Large Section Open-off Cut in Alternate Excavation under GoafAbstract:
In order to realize the safe and efficient construction of the one-time roadway-forming technology of alternating excavation of large-section open-off cut under close goaf, taking the geological conditions and mining conditions of II7322 working face and II8224 working face of Renlou Coal Mine as the research background, the similar simulation, theoretical analysis and field measurement were used. The influence of surrounding rock movement deformation and stress evolution on the stability of surrounding rock in the process of open-off cut under close goaf was studied. The results show that the maximum failure depth of the floor rock in the goaf is 4.56 m, the undamaged part of the fine sandstone above the roof of the II8224 open-off cut is classified as poor IV rock mass, and the siltstone is classified as medium III rock mass. The maximum stress of goaf floor is lower than the material strength of similar material simulation experiment, and the goaf mining has little influence on the stability of II8224 open-off cut roof. The secondary disturbance of surrounding rock stress will be caused by the one-time roadway formation of open-off cut in large section alternate tunneling. The vertical stress fluctuation of surrounding rock in the side of open-off cut is the most severe, and the surface displacement convergence of the two sides is greater than that of the roof and floor. Attention should be paid to the support work of the two sides.
- 1
Preparation and micromechanical properties of steel slag-based gelling agent modified groutingAbstract:
To study the failure characteristics and mesoscopic mechanism of the grouting body under different cementing agent content, uniaxial compression experiments were carried out on the specimens, and the two-dimensional discrete element simulation of the grouting body was carried out by PFC software to analyze the shear failure behavior and displacement field distribution of the grouting body after failure. The results show that the unconfined compressive strength and elastic modulus of the grouting specimens increase exponentially with the increase of the steel slag base gelling agent content, and the failure strain shows a parabolic function with the increase of the grouting agent content. The mechanical parameters and the stress-strain relationship of the grouting body are obtained by discrete element simulation, and the simulated results are in good agreement with the measured results. With the increase of the content of steel slag based gelling agent, the failure mode of the grouting body gradually changes from crushing failure mode to shear failure mode. The displacement vector field of the particles is obtained by discrete element simulation, which accurately reflects the failure mode of the grouting body under uniaxial compression load.
- 1
Study on the Influence of Weak Interlayer on the Stability of Deep Roadway Surrounding Rock in Gold MineAbstract:
The stability of roadway surrounding rock with weak interlayer is a major problem encountered in the deep mining of the gold deposit in Southwestern Guizhou. In order to ensure the safe and efficient production of the mine, the analysis model of the influence of different weak interlayer occurrence on the stability of roadway surrounding rock is established with the numerical simulation soft, the influence of dip Angle of soft interlayer and buried depth of roadway on the stability of roadway working face is studied. The results show that the dip Angle of interlayer is from 0 to 40, and with the increase of the dip Angle, the deformation of surrounding rock and the volume of plastic zone both increase first and then decrease. With the increase of the distance between the soft interlayer and the roof, the displacement at the vault gradually decreases, the displacement at the bottom and two sides of the arch has little change, and the volume of the plastic zone gradually decreases. The deformation and failure of the roadway is the largest when the soft interlayer is 5m away from the roof. With the increase of buried depth, the deformation of surrounding rock and the volume of plastic zone increase gradually. The research results can provide some reference for similar roadway engineering support.
- 1
Study on Performance of Glass Fiber Reinforced Cement-based Filling MaterialAbstract:
In order to solve the technical problems of poor consolidation effect of deep filler, low strength of filler and easy cracking, the cementitious material was prepared with volcanic ash materials such as blast furnace slag and fly ash, and glass fiber was used as the reinforcing agent of composite filler material. A four-factor, four-level orthogonal design was used to investigate the effects of fiber admixture, fiber length, water glass modulus and water reducing agent admixture on filling slurry collapse, diffusivity, filling body compressive strength and filling body damage mode. The results show that (1) the slurry collapse and diffusivity are negatively correlated with the fiber dosing and fiber length, and positively correlated with the water reducing agent dosing, and the water glass modulus is not a key factor affecting the flowability of the slurry. (2) The fiber has a facilitating effect on the development of the strength of the filling body, but not the higher the fiber admixture and the longer the fiber, the better the improvement effect. When the fiber admixture is 0.3% and the fiber length is 6 mm, the compressive strength of the filling body reaches the optimal value at all ages. With the increase of the water glass modulus, the compressive strength is rising first and then decreasing, and the water glass 1.4 M is the turning point of the change of compressive strength. (3) The fiber plays a bridging role in the filling body, increasing the ability of the filling body to resist external deformation, and the fiber-doped filling body maintains good integrity, and the surface of the specimen contains several microcracks, almost no penetrating main cracks. (4) Based on range analysis and variance analysis, the primary and secondary order of the influence of factors on the slump and diffusion of slurry is water reducing agent content>fiber content>sodium silicate modulus>fiber length, and the primary and secondary order of the influence on the compressive strength of backfill at 3, 7, and 28 days is fiber content>fiber length>water reducing agent content>sodium silicate modulus.
- 1
Study on Mechanical Properties of Rocks with Cross Fractures under Different Loading RatesAbstract:
Uniaxial compression tests with different loading rates were carried out on cross-crack rock-like specimens to study and analyze the influence mechanism of loading rate on the mechanical properties of specimens, and the failure process was analyzed with the aid of acoustic emission system. Conclusions were drawn as follows: (1) The peak stress intensity of the specimen presents a positive correlation with the loading rate, and the amplitude of the peak stress increases first and then decreases with the increase of the loading rate in an inverted "V" shape. (2) Before the stress peak, there is a quiet period of 0.15~4.8min ringing count, which gradually decreases with the increase of loading rate; The AE active interval will also be reduced from 60min to 12min. When the loading rate is low (δ≤0.2mm/min), the acoustic emission ringing count shows the characteristics of high frequency and high amplitude. At high loading rate (δ>0.2mm/min), the ringing count shows the characteristics of low frequency and high amplitude. (3) The failure mode of the specimen is mixed tension-shear failure. When the loading rate is low, the tensile crack is the main failure mode, and when the loading rate is high, the shear crack is the main failure mode.
- 1
Study on the Distribution of "Three Zones" and Fire Prevention Parameters in Goaf of Complex Ventilation Fully Mechanized Mining FaceAbstract:
In order to master the "three zones" distribution and fire prevention parameters in goaf of double entry and double return complex ventilation fully mechanized mining face, the spontaneous combustion fe propulsion speed and safe ventilation volume are determined by numerical simulation and theoretical calculation. The results show that the critical temperature of spontaneous combustion of No. 6 coal is about 70℃; Under the complex ventilation conditions, a larger heat dissipation zone and oxidation zone are formed at the air inlet side, which is not conducive to the prevention of goaf fire; With the increase of nitrogen injection depth, the area of oxidation temperature rise zone increases obviously at first and then decreases greatly. When the nitrogen injection volume is 420m3/h, the appropriate nitrogen injection depth is 30~50m; The minimum advancing speed of the working face under the condition of nitrogen injection of 420m3/h and no nitrogen injection is 1.33 and 1.78m/d respectively. The existing ventilation volume can meet the requirements of safe ventilation volume under nitrogen injection conditions.
- 1
Research on optimization of structural parameters of upward cut and fill mining method based on numerical simulationAbstract:
The average dip Angle of a gold deposit in Shandong Province is 30o, and the footwall lithology is stable, but there are local graphite mineralization and joint development problems in some areas. The surrounding rock of the hanging wall is broken, the alteration and graphitization are serious, and the overall stability is poor. The upward horizontal stratification mining method is adopted for mining. There are some problems such as roof caving in the mining process, which seriously threaten workers" safety. In this paper, four kinds of stope structural parameters are numerically simulated by FLAC3D. The results show that with the increase of room width, the plastic zone near the stope increases gradually, the stope roof displacement increases gradually, and the maximum principal stress increases gradually. The joint support of pipe joint bolt and resin bolt can effectively control the deformation of roof and two sides and reduce the stress concentration. The simulation results provide theoretical support for the determination of stope structural parameters.
- 1
Visual Fatigue Prediction for VDT Operations in Coal Mines Based on Multiple Machine Learning Algorithm ModelsAbstract:
To accurately predict the visual fatigue degree of VDT operators in intelligent coal mine is the key to reduce VDT errors and ensure the safety of intelligent coal mine. Through simulated coal mine VDT operation experiment, this paper collected the data of eye movement index and subjective and objective visual fatigue evaluation index values,PCA was used instead of the traditional subjective analysis method to calculate the weight of each evaluation index,FCM clustering algorithm was used to calculate the optimal visual fatigue classification number。On this basis, the VDT task visual fatigue threshold was taken as the output end and the subject"s eye movement data was taken as the input end to build a visual fatigue degree prediction model which integrated five machine learning algorithms. The results show that the optimal number of visual fatigue classification is 3, the accuracy of the prediction model constructed in this paper is 94.4%, and the average error rate of the prediction of the three types of visual fatigue degree is 3.7%. Compared with the five single machine learning algorithms, the accuracy and stability are significantly improved.
- 1
Characterization of Mesoscopic Deterioration of Sandstone Exposed to Freeze-Thaw CyclesAbstract:
In order to investigate the microstructure evolution of rock pores structure under cyclic freezing and thawing, a series of freeze-thaw cycle tests were carried out by using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) apparatus. The results show that when the number of freeze-thaw cycles is greater than 60, the T2 spectrum area enclosed by the mesopore region gradually increases. When the number of freeze-thaw cycles is reached to 120, the structural deterioration caused by freezing force is irreversible, the right peak area of T2 spectrum increases significantly compared with other conditions, and the porosity of sandstone gradually increases with a power exponential function. The micropores in rocks expand and connect due to the influence of water migration and freezing, and the small pore structure continuously evolves into mesopore and macropore structures. The fractal dimension of pore structure is negatively correlated with increasing freeze-thaw cycles. In addition, the correlation of pore throat fractal is higher than that of pore diameter. The results are helpful to understand the mechanism of frost heaving cracking and freeze-thaw collapse of rock mass in cold regions.
- 1
Study on compound mining method of ore body with variable occurrenceAbstract:
For the No. 1 ore body at Jintang pithead of Huangjindong Gold Mine in Hunan Province，It has the characteristics of occurrence of ore bodies with gentle, thin and variable occurrences。Traditional mining methods for this type of ore bodyThere are shrinkage method, room and pillar method[1], comprehensive method and other subsequent filling mining methods，However, this kind of mining method has the disadvantages of low efficiency[1-3], low mechanization, low recovery and high safety risk。By analyzing its changeable mining technical conditions，The combined mining method of upward horizontal cut and fill mining method and inclined vertical slicing mining method is studied by means of multi category comparative analysis，Developed the stope engineering layout system for co mining，The combined mining of zoning, slicing and slicing has been developed，Realized safe and efficient mechanized mining，The final statistics show that the stope production capacity has doubled by 86t/d，Control loss rate is less than 6.3%，Control dilution rate less than 5%，Comprehensive mining cost is 74.1 yuan/t，15.4 yuan/t lower than before，Effectively avoid the safety risk of personnel working under high roof，The composite mining method studied has a good popularization prospect。
- 1
Study on Stability Analysis and Treatment of Waste Disposal Site Which under Condition of Tailings ReservoirAbstract:
The stability of the Waste Disposal Site is not only related to the mechanical properties of its own rock and soil materials, the waste disposal technology, the waste disposal site parameters, the surface water and the groundwater, but also seriously affected by the properties of the basement rock and soil. In this paper, the waste disposal site with part or all of its base being tailings pond is defined as the waste disposal site under condition of tailings reservoir. Taking a waste disposal site under condition of tailings reservoir as an engineering example. the three-dimensional geological model of the waste disposal site is established with the help of SURPAC and FLAC3D software. and the physical and mechanical parameters of each group of rock and soil are obtained by test method. Then analyze or calculate the stability and safety factor of the waste disposal site with the help of FLAC3D software. The results show that there are two slip risk areas in the slope which namely Slip Risk Area I and Slip Risk Area II, and the safety factor of slope under rainfall condition is 1.10 that the safety factor reserve is insufficient. According to the above slope stability analysis results, the waste disposal site treatment plan is formulated which is unloading in slip risk area and improving internal drainage system. Once again, FLAC3D is used to calculate the safety factor of the waste disposal site. The results show that the safety factor has been greatly improved, that is the implementation of the treatment scheme can improve the stability of the waste disposal site. The research methods and results of this paper can be used for reference in the stability analysis and treatment of similar waste disposal site.
- 1
Study on Influence of Local Double Line of Filling Pipeline Transportation on Slurry Concentration and Pipeline WearAbstract:
The filling pipe network gradient has great changes due to the complicated laying conditions. The filling concentration is affected and the pipeline wear is accelerated when the local gradient is unreasonable, which causes the decreasing of filling quality and the increasing of filling cost. The flowability test of full-tailings filling slurry and the pipe network laying situation analysis has finished to exploration the phenomena of low concentration and serious wear of filling pipeline in a mine. The results shows that: Concentration needs to be sacrificed to meet liquidity requirements where the local surface filling pipeline is 7.51. Pipeline wear intensified due to small underground overall filling gradient (mostly close to 2-4), low concentration and long free falling section of vertical pipeline. By redesigning the surface filling pipeline to reduce the local gradient to 5.5 and adding pressure relief facilities to horizontal pipeline, the slurry can be transported to the goaf at a reasonable flow velocity with structural flow state to control the abrasion at a acceptable level.
- 1
Research on hydraulic separation and sedimentary law of upstream tailings in valleyAbstract:
Abstract：In this research, the physical characteristics of upstream tailings in valley were taken as the research object, and the particle classification and specific gravity tests of 85 groups of tailings from 13 boreholes were completed, and the hydraulic separation and sedimentary law were studied combined with the tailings tests.The results show that the particle size is characterized by "mixed coarse and fine particles at the shallow part and dominated by fine particles at the deep part" and "mixed coarse and fine particles at the front of the dam and dominated by fine particles at the bottom of tailings". The specific gravity is characterized by "lower specific gravity at the shallow part and higher specific gravity at the deep part" and "lower specific gravity at the front of the dam and higher specific gravity at the bottom of tailings". The formation of the lens and the mixed area of tailings is mainly caused by evaporation consolidation and the fan-shaped multilayer accumulation of tailings.The particle size and water characteristics of tailings are the main factors affecting the sedimentation rate of tailings.It has important reference value for the study of mechanical properties and safety production of tailings.
- 1
Application of Mechanical Rock Breaking Technology in the Mining of Broken ore BodyAbstract:
The broken soft rock ore body uses the drilling and blasting method of approach mining, which is difficult to achieve self-stability in the surrounding rock affected by the blasting vibration, and in the excavation process, and the support workload of the approach road is large. In order to solve the problems of blasting mining, which is easy to collapse, large support capacity and low mining efficiency, the feasibility of milling machine excavation mining instead of drilling and blasting mining is investigated. Research and application of the milling machine machinery in the crushing ore body inlet mining, to solve the problem of drilling and blasting method affecting the normal mining of the mine. By milling machine in summer gold mining actual application case, determine the milling machine machinery mining can replace 85% of blasting mining, comparing milling machine mining and blasting mining method in safety, environmental protection, economic benefits, etc, the results show that the milling machine tunneling mining road stability improvement, mining efficiency increased more than 50%, the support workload reduced by 40%, filling jacking rate increase, ore recovery rate increases, mining costs dropped sharply, achieved good safety, economic and social benefits.
- 1
Stability Analysis of Deep Shaft Surrounding Rock Based on Acoustic Method and Block IdentificationAbstract:
Determination of loosening zone of shaft surrounding rock is very important for stability analysis and support design. In order to explore measurement and wedge identification technology of loosening zone of deep shaft surrounding rock, this paper uses ultrasonic logging method to determine the loosening zone of shaft surrounding rock based on the background of main shaft -1400m section under construction in Shaling Gold Mine. Based on the information of joint and fissure in surrounding rock obtained from engineering geological survey, the dominant joint group of surrounding rock is determined by Dips, and the main wedge of surrounding rock is identified by Unwedge, geometric parameters of each wedge are obtained and stability analysis is carried out. The result shows that the range of surrounding rock loosening zone is 0.8~2.8m, and the dominant joint groups of surrounding rock are three groups. The overall safety factor of wedge is high and the drop risk is low. The research results can provide reference for support design and support parameter optimization of Shaling main shaft, and can also provide reference for determination of surrounding rock loose zone and identification of unstable block in deep shaft.
- 1
Research on construction and management model of super-large copper-cobalt mines in AfricaAbstract:
The construction of super-large mines in abroad at complex environment faces severe challenges in the management of major projects. By analyzing the huge difficulties, challenges and characteristics faced by mining enterprises to achieve high-quality and high-efficiency construction under the background of complex environments, and on the investigating and summarizing the experience of modern engineering management, it points out the necessity of innovating the management mode of super-large mine construction projects. Taking the construction of a world-class super-large copper-cobalt mine in Africa as an example, from the perspective of new personnel organization, new measures for double-grasp and double-stability emergency coordination, new ideas for sub-module construction, new systematic 4Y management model, and new means of equipment, materials and material support Based on the six aspects of the new concept of organizational management system design, the targeted solutions and countermeasures for mine construction under the background of complex environment are proposed, and the optimized mine construction management mode under specific resources and environmental conditions in Africa is obtained, which is exploratory and innovative. Innovative, to ensure the sustainable development of the "Belt and Road" for extra-large mines in complex environments such as Africa.
- 1
Section Shape and Size Optimization of Stope Drift Approach under Mining-induced Ground Pressure Environment by Sublevel Caving MethodAbstract:
Only four stoping sections can be arranged in the non-pillar sublevel caving stope of the west second mining area of Longshou Mine. The mining pressure and mining demand of each section are different. It is difficult to meet the actual mining demand by using a single section shape and size. In order to realize the safe and efficient mining of ore in each section, the numerical simulation method is used to study the evolution law of mining-induced ground pressure in the mining process of non-pillar sublevel caving method. The results show that with the sublevel mining of the caving stope, the mining site pressure shows the law of increasing horizontal pressure and decreasing vertical pressure. Then, according to the variation law of mining-induced ground pressure, the section shape and size of the four sections in the stope are studied, and it is concluded that the straight wall semi-circular arch approach with a height×width of 4.2m×4.4m is recommended for the first and last sections, and the straight wall three-center arch approach with a height×width of 3.8m×4.4m is recommended for the second and third sections. Finally, the research results are applied to the field production practice. While ensuring the stability of the stope, the recovery rate of the segmented ore reaches 103%, the depletion rate is only 8.5%, and the monthly production capacity of the stope reaches 80,000 tons.
- 1
Study on roof pillar recovery method without retaining the roof layer of protection under loose tailings filling bodyAbstract:
A certain thickness of the roof layer is usually reserved to prevent the large-scale collapse of the overlying loose tailing filling body when roof pillars are recovered. However, retaining the roof layer of protection will inevitably lead to the loss and waste of ore resources. A recovery method of horizontally isolated pillars was proposed without retaining the roof layer in the work. The haulage roadway of hanging and foot walls was used to arrange grouted anchor cables and bolts at intervals in the tailing filling body. Artificial false roof was formed to maintain the mining-field stability of isolated pillars and completely recover roof pillars. The work introduced the technical content and construction technology of recovering and arranging artificial false roof without retaining the roof layer under the loose tailing filling body and its advantages. The method was compared economically and technically with the method of retaining the roof layer to recover roof pillars by taking a lead-zinc mine in China as an example. Each mining field could get an additional income of CNY 1.4078 million with the proposed method. The benefits of the mine have been greatly improved when safe production was ensured. The work provides technical guidance for mines with roof pillars recovered under the loose tailing filling body.
- 1
Study on internal stress evolution law of ultra-high sublevel caving orebodyAbstract:
In order to study the evolution law of internal stress in ultra-high sublevel caving orebody, and physical model, numerical simulation and theoretical analysis are used to study. A self-made physical test model with a similarity ratio of 1 : 50 was used to carry out ore drawing tests on 60 m, 70 m and 80 m sections respectively and to study the internal flow law of orebody. Monitoring and analysis of internal stresses in the ore body by discrete element numerical simulation. The result shows that the ore drawing height will increase the longitudinal development speed, accelerating stress arching speed and strength. The height of drawing is positively correlated with the falling distance of upper ore rock and the stress arch is more easily formed inside the ultra-high stage ore body. The lower the vertical stress of the granular particles closer to the center at the same level, the higher the buried depth, the greater the vertical stress, and it will shift to the horizontal direction, and the center of the stress arch will shift with the particle flow.
- 1
Simulation Study on Dust Transport Law of Truck Road in North Open-pit Coal MineAbstract:
Truck road transport is one of the largest sources of dust in open-pit coal mines, and dust pollution seriously damages the health of occupational population in coal mines and affects the visibility of truck drivers, posing a major safety hazard. Based on the truck road transportation operation of North open-pit coal mine in Huolin as the research background, the three-dimensional flow field model of trucks was established by using FLUENT 19.2 software, and the influences of vehicle type, vehicle speed, wind speed and road moisture content on road dust transport law were analyzed respectively. The results show that: (1) Vehicle movement has a large disturbance to the outflow field, the airflow near the rear of the vehicle and on both sides of the wheels is more chaotic, and the disturbance intensity behind the vehicle is greater than that in front of the vehicle;(2) The dust concentration in the driver's breathing area is low, and the dust concentration between the front and rear wheels and behind the vehicle is high;(3) When driving upwind, with the increase of vehicle speed, the faster and farther the dust transport speed is, the higher the dust concentration is on both sides of the wheel and the rear area of the vehicle, and the dust concentration at X=0 m increases first and then decreases;(4) When the wind speed is small, the dust concentration near the wheels is the largest. With the increase of the wind speed, the dust is concentrated in the rear and rear of the vehicle, which firstly increases and then decreases and tends to be stable;(5) When the amount of water sprayed on the road is 0.15 L/m2, the road moisture content is about 4.1%, so that the dust concentration on the road meets the dust removal requirements.
- 1
Evaluation of Initial Mining Pressure Characteristics and Support Adaptability of 1310 Isolated Working FaceAbstract:
Due to the superposition of mining stress on the adjacent sides, the mine pressure of the isolated working face is more intense than that of the general working face. The research method combining on-site measurement and numerical simulation was used to analyze the mine pressure characteristics and the adaptability of hydraulic support during the initial mining of the 1310 island face of Xiaoyun Coal Mine. The results are as follows: through on-site measurement, it is concluded that the initial pressure step distance of the old top during the initial mining of the 1310 working face is 40~50 m, the average pressure step distance of the cycle is about 13 m, and the compressive load coefficient is 1.4~1.9; through numerical simulation, the stress change and plastic zone distribution characteristics of the island working face are analyzed, and the mining severe influence zone is within 10~15 m from the coal wall, and the advanced pressure influence range is about 40 m. Through the formula calculation and on-site measurement, the resistance of the hydraulic support of the working face is analyzed, and it is verified that the existing ZY8000/20/42D bracket can meet the requirements of 1310 working face support, and can effectively ensure the safe production of the working face.
- 1
Evolution law and stability analysis of surface rock displacement induced by underground mining in a mineAbstract:
With the development of deep orebody mining, underground mining is easy to cause surface subsidence deformation, thus causing disturbance to surface industrial sites and structures. To analyze the stability of the surface and industrial site in the process of underground mining, an underground mine was taken as the research object, and the displacement change of the surface and industrial site was analyzed by MIDAS-FLAC3D coupling simulation method, and the stability of the surface and industrial site was evaluated by combining the rock displacement index. The results show that in the process of open-pit mining, the displacement index of surface and industrial site and rock displacement of the underground mine does not exceed the safety permit range. The research results can provide a reference for the stability analysis of the surface in open-pit underground mining.
- 1
Prediction and analysis of backfill strength under the effect of multiple factorsAbstract:
In order to analyze and predict the strength of backfill under the influence of multiple factors, filling ratio experiments were conducted, and a new filling strength prediction model was established based on support vector machine regression (SVR) model combined with grey wolf optimization (GWO). The experimental results showed that the strength of the filling body increased with the increase of cement dosage and slurry concentration and then decreased with the increase of coarse and fine aggregate ratio. The coupling effect of slurry concentration and cement dosage has the most significant effect on the 7d strength of the filling, the coupling effect of cement dosage and coarse and fine aggregate ratio has the most significant effect on the 7d strength of the filling, and the coupling effect of slurry concentration and coarse and fine aggregate ratio has the most significant effect on the 28d strength of the filling. The strength prediction model with the slurry mass concentration, cement admixture, artificial sand tailing ratio and maintenance time as input variables and the uniaxial compressive strength of the filler as output variables was successfully established by using GWO to iteratively find the optimization of the penalty factor c and kernel function parameter g in SVR. The root mean square error (RMSE) of the model test set is 0.187, which is 95.07% and 78.68% lower compared with the original SVR and PSO-SVR; the coefficient of determination R2 is 0.993, which is 39.66% and 19.35% higher compared with the original SVR and PSO-SVR.
- 1
Preparation and Performance Study of Double Network Composite Colloid for Coal MineAbstract:
Based on the inadequacy of existing coal spontaneous combustion control means such as grouting and filling at home and abroad, this paper exploits the unique properties and structure of nanopolymers and the performance advantages of polymer colloids, proposing a new composite colloid. Under alkaline conditions, polyvinyl alcohol is cross-linked with boric acid to form a first network and a second network with polyacrylamide and polyvinyl alcohol using intermolecular hydrogen bonds to form a polymeric space network, the double network composite gel was then prepared using the good swelling and water absorption characteristics of montmorillonite. Optimisation of composite gel ratios by measuring gel formation time, permeability and viscosity; Analysis of the changes in the release of signature gases from raw coal samples and composite colloid-treated coal samples by means of barrier performance tests; Comparison of the changes in the functional groups of the two coal samples using FTIR spectroscopy and calculation of the changes in peak areas of the different functional groups. The experimental results show that the double network composite gel has a good spontaneous combustion deterrent effect and can well inhibit the oxidation of coal spontaneous combustion.
- 1
Experimental study on physical model of deformation characteristics of red shale roadwayAbstract:
In order to study the deformation characteristics of red shale roadway, this paper takes the red shale roadway in the second mine of Ping " an Phosphate Mine in Kaiyang County, Guizhou Province as the research object. The bedding surface and secondary rupture surface of sedimentary rock are simulated by layer-by-layer laying of physical finite element plate. The high-speed camera is used to collect real-time images. The evolution law and rupture characteristics of cracks in the process of roadway failure are analyzed. Combined with the infrared image sequence collected by infrared thermal imager, the mechanism of dynamic disturbance on roadway instability and failure is analyzed. The results show that with the excavation of the orebody in the stope, the displacement change of the surrounding rock of the roadway moves along the dip direction of the rock stratum, and the horizontal and vertical displacement of the roadway roof is large. In the process of excavation, the roof energy gradually accumulates and the temperature increases, but when it is in the pressure relief area, the temperature in the roadway continues to fall and maintain at a low temperature. The experimental results can provide a theoretical basis for the safety control of red rock roadway under dynamic disturbance.
- 1
Experimental study on the performance change of the electric diaphragm pump for mining under high altitude environmental conditionsAbstract:
With the decrease of resources in low altitude areas, the exploitation and utilization of metal mineral resources in high altitude and cold areas are becoming more and more frequent. However, the working performance of mechanical equipment is affected by high altitude environmental conditions. Therefore, it is of great practical significance to carry out the research on the influence of mining machinery and equipment efficiency under high altitude environment. The research group specially designed a set of low-pressure and low oxygen mining environment simulation experimental chamber, which can simulate the mine atmospheric environment at different altitudes, and test the performance changes of mine electric diaphragm pump at different altitudes. At different altitudes, the experimental study on the flow rate, inlet and outlet pressure, torque, speed and power of the electric diaphragm pump was carried out. The experimental results show that when the electric diaphragm pump operates in high altitude area, due to the low atmospheric pressure, the power and torque decrease. The torque and power decrease by 3.7% ~ 11.7% and 3.7% ~ 11.9% when the altitude is 1000m. When the altitude reaches 5000m, the torque and power decrease by 25.7% and 25.6%, respectively. The motor speed and flow rate are less affected by altitude. The inlet pressure changes with the elevation When the altitude reaches 5000m, the inlet pressure decreases by 79.2%.
- 1
Rock mass quality evaluation method and application based on weight fusion-improved extension cloud modelAbstract:
Rock mass quality classification is the basis of engineering design and construction, and its classification evaluation is an important problem to be solved in rock mass engineering. Aiming at the uncertainty and fuzzy randomness of rock mass quality grade evaluation, combined with the weight fusion method and the extension cloud model theory, a weight fusion-improved extension cloud model for rock mass quality evaluation is established. Firstly, the paper collects existing research results to establish an open indicator weight library,and integrate the weights obtained by multiple weighting methods based on the basic idea of cloud atomization．The rationality test of the index weight is realized through the cloud atomization condition, and then the comprehensive integrated evaluation index weight is obtained. Secondly, in view of the two different cloud entropy algorithms existing in the traditional extension cloud model, based on the game theory, the cloud entropy algorithm is integrated, and an improved extension cloud model is proposed. Combined to obtain the comprehensive evaluation characteristic value (defined as quality value in this paper) to determine the rock mass quality evaluation level, and use the confidence factor to test the credibility of the results. Finally, the improved extension cloud model is applied to an engineering case, and the results show that the evaluation grade of rock mass in this tunnel section is grade IV. The evaluation results are consistent with the actual engineering, and the results are accurate. Compared with the matter-element extension model and the traditional extension cloud model, the evaluation results are more accurate, which verifies the reliability and accuracy of the model. The model evaluation process has strong operability and can provide a new method for rock mass quality evaluation.
- 1
Prediction of Gas Emission from Mining Face Based on Unbiased Grey Markov ModelAbstract:
The prediction of gas emission in mining face is of great importance to mine gas prevention. In order to predict the gas emission from the mining face, the traditional grey GM (1,1) model is combined with Markov theory, and then the traditional grey GM (1,1) model is replaced by the unbiased grey GM (1,1) model to form the unbiased grey Markov model. The prediction results are optimized twice. By studying the gas emission data from the mining face of Jinda Coal Mine from January to October 2021, the change of the gas emission data from the mining face is excavated, It is predicted that the gas emission from the stope will be from November to December. The results show that the unbiased grey Markov model can not only reduce the inherent error of the grey GM (1,1) model itself, but also improve the accuracy of prediction. Through secondary optimization, the final average absolute error, average relative error and average prediction accuracy can be lower than those of the other three models, with specific values of 2.3%, 4.18% and 94.34% respectively. And combined with the field data analysis, the unbiased grey Markov prediction model after secondary optimization can well predict the gas emission of the working face.
- 1
Fracture Modes and Acoustic Emission Characteristics of Substratum Basalt under Uniaxial LoadingAbstract:
Based on uniaxial compression test of basalt with different bedding dip angles, AE technology was used to study the anisotropy, crack propagation and AE characteristics of layered basalt. The changes of AE energy and spike times during the failure process of layered basalt were analyzed, and the influence of AE B value on the failure of components was studied.??The results show that :(1) with the change of bedding dip Angle, the energy of basalt with different bedding dip Angle shows a sudden increase;??With the increase of inclination Angle, the number of energy surges increases gradually.??(2) By comparing the distribution of B value under different bedding inclination angles, it is found that the B value decreases with the gradual increase of loading level.??The B-value analysis can accurately judge the crack development degree and the damage of the test block.
- 1
Study On The Flow Characteristics Of Gas Extraction From Coal Deam Boreholes Under Different In-situ StressesAbstract:
In order to investigate the influence of different ground stress conditions on the flow law of coal seam gas extraction, based on the flow-solid coupling model, the corresponding numerical model was established by COMSOL, and different ground stress conditions were applied to the model respectively, and the influence of vertical ground stress and lateral pressure coefficient on coal seam gas pressure and permeability was investigated. The research shows that: when the vertical ground stress is greater at the deeper coal seam, the effective extrusion stress in the coal seam increases, and the permeability of the coal seam decreases, leading to the poor gas extraction effect; with the increase of the lateral pressure coefficient, the effective extrusion stress in the horizontal direction in the coal seam increases significantly, and the permeability of the coal seam becomes smaller, leading to the poor gas extraction effect; however, the effective extrusion stress in the vertical direction at the extraction borehole decreases with the increase of the lateral pressure coefficient However, the effective stress in the vertical direction of extrusion at the extraction borehole decreases with the increase of lateral pressure coefficient and even appears to stretch the coal body, resulting in the increase of permeability in this area with the increase of lateral pressure coefficient.
- 1
Study on In-situ Measurement Technology of Seafloor SedimentAbstract:
In order to solve the problems of inaccurate measurement and large measurement error in the in-situ measurement of the geotechnical parameters of deep-sea sediment, the in-situ minimum variable measurement method under high confining pressure, non-contact torque transmission technology under high confining pressure and continuous multi station operation technology of submarine towing were proposed. The in-situ testing instrument equipment for deep-sea sediment was developed, and the in-situ measurement of seabed was completed in 54 voyages and 70 voyages of China Ocean. Through the analysis of the in-situ measurement data of DY54 III-A3-TG01 station of the 54th voyage of China Ocean and the laboratory data on board, it can be seen that the seabed in-situ data measured by the equipment at the same station are highly consistent, which also shows that there are differences between the in-situ measurement data and the laboratory data on board, so it is of great significance to carry out the in-situ measurement of deep-sea sediments.
- 1
Preparation and properties of composite dust suppressantfor open-pit limestone mineAbstract:
In order to solve the problem of fine particulate pollution in open-pit limestone mines and avoid serious harm to human health, mechanical equipment and atmospheric environment, using xan-than gum (XG) and guar gum (GG) as synthetic substrates, acrylamide (AM) as monomer, sodium silicate (Na2SiO3) as hygroscopic, sodium dodecyl benzene sulfonate (SDBS) as wetting agent, and under the joint action of potassium persulfate (KPS) and Nn-methylene bisacrylamide (MBA), a kind of environmentally friendly composite dust suppressant for limestone ore with moderate vis-cosity, high wettability and hygroscopicity was synthesized by grafting polymerization. Through the structural characterization and performance tests of FTIR, SEM, TG, the results show that the synthesized composite dust suppressant has a large number of pore structures, the maximum py-rolysis rate corresponds to a temperature of 325.95 °C, compared with the water spray dust sample, the wind erosion loss rate and oscillation loss rate of the dust sample sprayed with the composite dust suppressant are reduced by 97.8% and 94.2%, and the compressive strength of the cured lay-er formed reaches 299kPa, which can meet the requirements of the mine for dust surface pressure. The synthesized dust suppressant has remarkable dust suppression effect and good thermal stabil-ity, and its use can reduce the problem of dust pollution in limestone mines, which meets the con-struction requirements of ecological mines.
- 1
Research on Key Technologies of Statistical Data Warehouse for Development and Utilization of Mineral ResourcesAbstract:
The statistical work of mineral resources development and utilization is a basic work of the natural resources management department. Its statistical data is an important basis for the country to formulate mineral resources planning, programme, policies and macro management. To implement the high-quality development of natural resources and ensure the safe and effective supply and scientific and rational utilization of energy resources, first if you want comprehensively, accurately and timely grasp the situation and trend of the development and utilization of mineral resources，you should focus on in-depth mining and analysis of the statistical survey data of the development and utilization of mineral resources, and find the mining development laws and problems. This paper mainly designs four themes of the mineral resources development and utilization data warehouse according to the statistical investigation system of mineral resources development and utilization and the business requirements of mineral resources management, determines to use the star model to design the multidimensional data model, and constructs the mineral resources development and utilization data warehouse through three steps of data extraction, data conversion and data loading, realizes the fixed table query, ad hoc query and analysis report. The achievement can conduct multidimensional analysis on development and utilization data, including drilling analysis, slicing analysis and rotation analysis.
- 1
Detection of Changes in Vegetation Coverage in Mining Areas based on Improved DeeplabV3+Abstract:
The monitoring of vegetation damage in open-pit mining areas is an important basis for ecological restoration and management of mining areas. Aiming at the problems of incomplete monitoring information and blurred edge of target area in the traditional open-pit mining area vegetation coverage change detection method, this paper proposes a mining area vegetation coverage change detection method that combines improved DeepLabV3+ and attention mechanism. This method uses the adaptive attention mechanism to obtain the information features of the vegetation image in the mining area, and introduces the MobilenetV2 with dilated convolution to reduce the network parameters and calculation amount of the DeepLabV3+ model, thereby improving the accuracy and efficiency of target detection in the vegetation area. The Deeplabv3+ optimization model realizes remote sensing monitoring and analysis of vegetation conditions in mining areas. The results show that the method can detect the time series changes of the vegetation damage in the mining area, and the segmentation effect is complete and accurate, the detection accuracy rate reaches 86.16%, and the speed can reach 68fps. Therefore, it can provide an effective basis for vegetation change detection and ecological environment management in open-pit mining areas.In the process of mining, with the increasing frequency of open-pit mining activities, the vegetation coverage around the mining area is bound to be damaged to varying degrees. Therefore, studying the changes in the vegetation coverage in the mining area can effectively understand the vegetation coverage in the mining area and its surrounding areas. The degree of damage is crucial to strengthening the monitoring and restoration of the ecological environment of the mine.
- 1
Risk Prediction of Roof Water Inrush in 3-1 Coal First Mining Area of Hongliulin MinefieldAbstract:
Shallow coal seam mining in northern Shaanxi Jurassic coalfield is mainly threatened by roof water, which mainly includes overlying weathered bedrock water and local burnt rock water. The water-richness of weathered bedrock and burnt rock is stronger than that of normal bedrock. When affected by mining fissures, it is easy to cause water inrush accidents. In this paper, the first mining area of 3-1 coal in Hongliulin Minefield is taken as the research area. Aiming at the roof weathered bedrock aquifer, five main controlling factors affecting the water abundance of weathered bedrock aquifer are selected, including the lithologic combination of weathered bedrock, the degree of weathering index, the thickness of weathered bedrock, the core recovery rate and the elevation of the top surface of weathered bedrock. The " water abundance index method " coupled with GIS and AHP is used to evaluate the water abundance of weathered bedrock aquifer. The water abundance of weathered bedrock is divided into three categories : strong water abundance, medium water abundance and weak water abundance. Aiming at the burnt rock aquifer, based on the data of transient electromagnetic geophysical prospecting, unit water inflow of hydrological hole and underground water exploration and drainage, the water abundance of burnt rock is divided into four categories : extremely rich water, strong rich water, medium rich water and weak rich water. According to the height development characteristics of the water flowing fractured zone, the damage degree of the roof aquifer is divided. Combined with the prediction results of the water abundance of the aquifer, the prediction map of the water inrush risk zoning of the 3-1 coal roof in the study area is drawn. The risk of roof water inrush in the study area is divided into four categories : extremely dangerous, large, medium and small. The prediction results can provide guidance for water control in 3-1 coal mining of Hongliulin Coal Mine.
- 1
Selection of Impeller Blade Number of Self - suction Flotation MachineAbstract:
The relationship between the impeller structural parameters and performance parameters of the self-priming flotation machine is complex, resulting in the structural optimization research process far behind that of the air-filled flotation machine. In order to study the number of impeller blades that is conducive to improving the circulation of the self-priming flotation machine, this paper uses CFD and experimental methods to analyze the influence of the number of impeller blades on the internal flow field characteristics and performance of the flotation machine based on the star radial impeller of JJF flotation machine. The results show that the number of impeller blades does not affect the circulation structure of the flow field, and can form a flow field environment suitable for mineral suspension and transportation of mineralized foam. When the number of blades is ( 4、6、8、10 ), with the increase of the number of blades, the axial flow velocity, turbulent kinetic energy, pressure difference of the liquid phase in the circulation tube and the vertical tube, and the performance parameters ( circulation amount, power consumption ) of the flotation machine gradually increase. When the number of blades continues to increase to 12, the axial flow velocity, turbulent kinetic energy, pressure difference and flotation machine circulation of the liquid phase begin to decrease, but the power consumption continues to increase because the spacing between blades is too small. When the number of impeller blades in the sample range is 10, the circulation of the flotation machine is the largest ; Within the allowable error range, the simulation values of impeller performance parameters with different blade numbers are in good agreement with the experimental values.
- 1
Research And Application of High Pressure Long Distance Sealing Technology for Coal Seam DrillingAbstract:
Aiming at the gas leakage problem of coal seam gas extraction in Sangbei Mine, this paper analyzes the causes of gas leakage in the current sealing process, development of high-pressure long distance self-adaptive bag sealing device, and optimizes the structure of the sealing device and the selection of supporting materials. The research results show that: (1) the low sealing grouting pressure and the "cross leakage" between the borehole and the coal seam borehole are the root causes of sealing hole leakage. The reasonable grouting pressure range of high pressure grouting sealing hole is 1.5MPA-2.0mpa, which can effectively seal the air leakage channel and coal seam cracks around the drilling hole; The sealing depth of the hole is designed to be 27 meters, which can effectively avoid the cross leak zone of the drilling hole. (3) The PE very high density (SS) material is selected to meet the high pressure and long distance hole sealing. The diameter of the extraction pipe is designed to be 40mm, and the wall thickness is 4.5mm to meet the strength requirements. (4) Through engineering application, the sealing hole leakage problem is solved, the average gas extraction concentration is increased by 53.6%, and the long-term effect is significant.
- 1
Application research on precise detection technology of complex mined-out area in open-pit mineAbstract:
In this paper, the application of precision detection technology is studied by using two kinds of precision detection equipment and 3D visualization modeling, taking the collapse of a complex gob in an open-pit mine as an example. The research shows that the SLAM UAV scanning system can enter the exposed goaf for scanning, and the C-ALS drilling 3D laser scanner can detect the hidden goaf. The two detection methods complement each other''s advantages and form a cm-level visual 3D model accurately, truly and quickly, which makes up for the limitation that personnel cannot enter the complex goaf in open-pit mine. The cause of the caving zone was analyzed by using the accurate three-dimensional model of the caving zone combined with the field engineering drilling practice. The cantilever pull-apart collapse model was adopted, and the 1190E drilling rig and D11T bulldozer with large specific pressure to the ground were selected as examples. The stability coefficients of the two equipment standing positions at 5m and 8m away from the caving pit edge were all above 1.2, which met the temporary operation conditions. The application research of precise detection technology provides a basic basis for the cause research and engineering management of goaf, which is of great significance for the safety protection of goaf geological disasters.
- 1
Influence of Different Stoping Sequence on Ore Drawing Effect in Pillarless Sublevel CavingAbstract:
In order to explore the influence of the mining sequence of pillarless sublevel caving on the ore drawing effect, a multi sublevel similarity physical experiment model of pillarless sublevel caving was established, and the influence of single stoping drift drawing and double stoping drift drawing on the dilution rate and the ore drawing effect without dilution was compared; At the same time, the discrete element numerical simulation single segment model is established to compare the ore recovery effect. It is found that: ① in the process of mining, ore dilution occurs earlier in the single drift stoping than in the double drift stoping; ② The residual ore at the ridge of the last segment is generally triangular in shape, and there is no obvious difference between the two methods of mining the residual ore at the ridge; ③ The overall change of ore dilution rate and pure ore recovery rate of single stoping drift ore drawing or double stoping drift ore drawing is consistent, but the effect of double stoping drift ore drawing is better than that of single stoping drift ore drawing in physical experiment, and the ore recovery rate of single stoping drift ore drawing is about 92.83% of that of double stoping drift ore drawing. Further research shows that the double drift extraction method has a large amount of pure ore recovery, slow decline and change of the curve of the ore rock contact surface, late deformation of the ore rock contact surface, and less loss rate than the single drift extraction, which can effectively improve the ore drawing effect.
- 1
Study on Macro-micro Size Effect of Broken Gangue under Confined CompressionAbstract:
The mechanical properties of gangue materials in the process of pressure are greatly affected by the size, and the laboratory mechanical parameters are difficult to represent the engineering scale. In order to study the size effect of broken gangue under confining pressure, the influence of specimen size on the bearing capacity of broken gangue was analyzed from macro to micro scale through laboratory tests and particle flow numerical simulation. The results show that: (1) The diameter of the specimen has a significant effect on the macroscopic mechanical properties of gangue, and the anti-deformation ability of gangue decreases obviously with the increase of diameter; (2) The variation of porosity of broken gangue increases with the increase of specimen diameter; (3) During the compression process of coal gangue, the blocks on both sides are crushed by extrusion, and the fine particles are gradually filled into the middle of the specimen. Therefore, the particle coordination number increases with the increase of the deformation space of the specimen; (4) During the stress loading stage, the particles gradually break up, and the particle force chain evolves from "ring force chain" to "columnar force chain". The average contact force change rate shows that the specimens with large volumes are more likely to reach the limit of compressive deformation ability. (5) The gangue is mainly subjected to tensile failure, and the degree of block breakage increases with the increase of specimen size. The research results are of great significance to the selection of filling materials in backfill mining.
- 1
Study on Heating Flotation to Normal Temperature Flotation for a Low-grade Scheelite Ore in HunanAbstract:
In view of the problems of high energy consumption, high cost and poor recovery rate of heating and cleaning operation in a low-grade Scheelite Flotation Production in Hunan,an experimental study on the heating flotation process of scheelite to normal temperature flotation process was carried out. The test results show that using CK-5 as scheelite collector, sodium carbonate as pH regulator, Water glass is a silicate gangue inhibitor, CF is a special gangue inhibitor such as fluorite, calcite and fine mud, the flotation index of WO3 grade of Scheelite Concentrate is 50.20%, and the recovery rate is 72.54%. The transformation of scheelite heat flotation process to constant temperature flotation process is successfully realized, and the recovery rate of scheelite is 7% higher than that of on-site production.The research results can provide reference for the transformation of the heating flotation process of scheelite to normal temperature flotation in domestic and foreign concentrators to achieve energy saving and consumption reduction.
- 1
Study of flexural properties of specimens with anchors under three-point bending test conditionsAbstract:
During the mining process, the arrangement of bolt is crucial to the support of roadway roof. In order to study the flexural properties of the unanchored and anchored roof rock, standard rock specimens were made in this paper, and three-point bending tests are carried out on the specimens using the variable stiffness coal rock dynamic test failure tester. The results show that the peak load of the specimen increased significantly after the anchor was added, compared with the unanchored specimen. When the anchor bolt spacing increases from 20-20mm to 40-40mm, the peak load of the specimen increases first and then decreases. When the spacing is 30-30mm, the specimen gets the maximum value. Tensile and compressive strains are generated on the upper and lower surfaces of the specimen during bending damage, and the tensile strain on the lower surface is generally greater than the compressive strain on the upper surface. The strain values generated on the upper and lower surfaces of the unanchored specimens were smaller than those of the anchored specimens, and brittle damage occurred more quickly in the unanchored specimens under axial load. When the anchor spacing is increased from 20-20mm to 30-30mm, the strain produced by the upper and lower surfaces is close. It indicates that reducing the anchor spacing can increase the stability of the rock mass to some extent, but when the spacing reaches a certain value, the strengthening effect on the overall stability of the specimen is not significant.
- 1
Study on Support Parameter Optimization of Hollow Grouted Bolt in Deep Roadway of Jinfeng Gold MineAbstract:
In order to improve the support efficiency of 00# horizontal roadway in Jinfeng Gold Mine, a hollow grouted bolt is proposed. The diameter, length and spacing of the anchor are taken as the research parameters by using FLAC3D numerical simulation method. The optimal support parameters are considered from the aspects of reducing the surface displacement of the roadway, the volume of the plastic zone, the stress of the surrounding rock and saving the economic cost. The results show that under the original support parameters, the supporting effect of split-set bolt is worse than that of hollow grouted bole, and the plastic failure area of roadway is wide, the volume of plastic zone is 8668.8 m3. After optimizing the parameters of hollow grouted bolt, the displacement of roadway sides is 174 mm, which is 51.1 % higher than the original support. The displacement of roof and floor is 144 mm, which is 23.9 % higher than the original support. The vertical stress of the roadway is 13.2 % lower than that of the original support, and the overall stress level is decreasing. The plastic zone volume is reduced by 59 % compared with the original support, and the plastic failure range is obviously reduced. The field monitoring results show that the new support scheme can achieve stable control of roadway surrounding rock in a shorter time.
- 1
Wang Wencai1, Wu Zhoukang1, Wang Pang1, Su Baoshan2Abstract:
In order to effectively solve the problem of large roadway deformation after deep coal roadway excavation, For the auxiliary transport back to the wind roadway of a mine, Characteristics of strong surrounding pressure, weak bearing capacity and high deformation, Under the analysis of the bottom of the rock properties, the deformation characteristics of the roadway and the original support of the roadway method has been unable to maintain the stability of the roadway, By performing the calculation of the plastic region, Thus, the method of controlling the surrounding rock deformation of the roadway is obtained: The anchor-net-sprayed concrete-cable-steel composite support mode makes the roadway face less deformed and increases the plasticity of the surrounding rock, Support for the roadway, FLAC3D software is combined with field engineering measurement to verify the rationality and practicability of the joint support mode of "anchor-net-net-spray-cable-steel".The anchor-net-sprayed concrete-cable-steel composite support mode makes the roadway face less deformed and increases the plasticity of the surrounding rock, the maximum offset value of the two sets is 80mm, 80.45% compared with the original support, and the offset control ability of the two sets is increased by 62.5%.It can provide a reference for other similar roadway support works.
- 1
Research on Multi-directional Destructive Technique of Close Extra Thick Interlaced Coal SeamAbstract:
In order to solve the problems of high engineering cost, long construction period and low efficiency of abatement in strip gas extraction and abatement technology in the bottom extraction lane, we propose to use the gangue layer to open the drilling field and construct long directional boreholes to pre-pump coal seam strip gas to achieve regional abatement in Shanxi Shangliang coal mine 3-2# and 3-3# near extra thick gangue coal seam as the engineering background. Through the establishment of coal seam strip gas multi-directional seepage model, the most unfavorable extraction theory is introduced, and the undifferentiated numerical simulation of coal seam gas pressure change is carried out, meanwhile, the two-way comparison analysis of the effect of the two techniques is carried out by combining the field data. The results show that the coal seam gas has a stronger tendency to transport in horizontal direction due to the restriction of the top and bottom plates in the cascade directional long borehole multi-directional abatement method, and the gas pressure reduction contours are elliptically distributed; the gas pressure reduction contours are circularly distributed in the bottom pumping lane method. The proposed directional long drill hole multi-directional abatement technology enables 3-2# coal seam and 3-3# coal seam to reach the abatement requirement after 70d and 110d of extraction respectively, and the abatement efficiency is 55%-143% higher than that of bottom pumping lane, and the daily pure flow and concentration of extracted gas are 35% and 14% higher respectively, meanwhile, the construction cost is saved by 65% and the construction period is shortened by 56%, which can be used for the near It can provide a reference for the efficient management of gas in extra thick gangue coal seam.
- 1
Mineral Transformation of Magnetite in Concrete Environment and Effect on the Concrete StrengthAbstract:
The magnetite ore was taken as the example which was ground into fine powder, and immersed in the simulated concrete pore solution for a certain age. The chemical stability of magnetite(Fe3O4) under the condition of concrete was investigated by analyzing the mineral transformation with XRD. In addition, the concrete specimen was prepared with magnetite ore to substitute partial general gravel, and cured in water of 20℃and 80℃separately, and the strength was tested at the scheduled age. The experiment results show that magnetite (Fe3O4) can change to hematite (Fe2O3) in the simulated concrete pore solution, and adding part of magnetite into concrete has no adverse effect on the strength of concrete.
- 1
An analysis of the interaction regulation path affecting miners' safety performance: Leadership dualistic mental perspectiveAbstract:
In order to ensure the safety behavior of miners in coal mine work, improve the human ecological environment of miners, and improve the safety performance of miners, the binary mental cognitive model is analyzed and applied in the field of coal mine. Focuses on three dimensions of leadership of binary mental perspective, based on the efforts of restoration theory, social exchange theory, the perspective of the dualistic mind to the first dimension of emotional intelligence as the primary effect, the introduction of individual level of miners subjective well-being as a intervening variable, the second dimension analysis leadership contingency punishment, third dimension leadership responsibility regulation role of self-efficacy, The interactive moderating effects of the above factors on miners' safety performance were studied. Based on the analysis of 224 effective samples, the results show that the emotional intelligence of miners' leadership not only directly and significantly affects the safety performance of miners, but also indirectly affects the safety performance of miners through the cross-level mediating effect of miners' subjective well-being. From the perspective of dualistic mind, leadership responsibility self-efficacy plays a positive moderating role, while leadership non-contingency punishment plays a negative moderating role, and leadership responsibility self-efficacy can buffer the negative effect of non-contingency punishment.
- 1
Study on the weakening effect of rainfall on the stability of slopes in open pit mines with soft substrate drainage fieldsAbstract:
s:Under rainfall conditions, the strength, cohesion and internal friction angle of the rock mass are severely affected, and the rock mass is subject to the static and dynamic effects of surface water and groundwater, so rainfall seriously affects the stability of the slope. In this paper, five limit equilibrium methods, including the Bishop, Spencer, Morgenstern-Price (M-P), Janbu and Sarma methods of Geostudio software, are considered to carry out comprehensive numerical simulations of two-dimensional drainage field models for natural and rainfall conditions. Analysis of the conditions of application and underlying principles of the 5 limit equilibrium methods and evaluation of the slope stability safety factor by mean of the AHP analysis weighting method. Analysis of rainfall weakening of the slope stability of a weak substrate drainage field in an open pit mine, calculation of the discount factor for each profile and analysis of the mechanism of the weakening of the slope stability of a weak substrate drainage field. The test results show that the safety coefficient of the engineering design scheme is larger under all working conditions, the influence of rainfall on slope stability is significant, and the stability safety coefficient of the slope of Liwu drainage field shows the law of decreasing with the increase of rainfall, indicating that the stability safety coefficient of Liwu drainage field has significant seasonal characteristics, and the safety coefficient of the engineering of the drainage field decreases significantly during the rainfall season. The results of the study provide a more comprehensive research methodology for the analysis of the stability of slopes with weak substrates.
- 1
Study on the Law of Time Differential Development of Cracks on Coal-rock Composite Anchor Based on Pull-out TestAbstract:
In order to further reveal the law of time differential development of cracks on the coal-rock composite anchor during the pull-out process, based on the verification of the phenomenon of time differential development of cracks on the coal-rock composite anchor under the inclined coal-rock interface dip angle by using the numerical simulation method, the bolt pull-out test was carried out, and the law of time differential development of cracks on the coal-rock composite anchor under the conditions of different pull-out rates and coal-rock interface dip angle was studied. The results show that the increase of the pull-out rate will reduce the overall failure and debonding time of the coal-rock composite anchor under the dip angle of the coal-rock interface is 0°, but has no obvious effect on the time differential development of cracks between the coal and rock. Compared with the pull-out rate, the dip angle of the coal-rock interface has a significant impact on the time differential development of cracks on the coal-rock composite anchor. When the dip angle of the coal-rock interface is less than 45 °, the overall failure and debonding of the coal-rock composite anchor takes longer, making the time differential development of cracks difference between the coal and rock more obvious, with an interval of about 34s. When the dip angle of the coal-rock interface increases to 60 °, the time required for the overall failure and debonding of the coal-rock composite anchor body is greatly reduced, and the time differential development of cracks difference between the coal and rock is significantly reduced, with the interval time reduced to about 24s.
- 1
Quantitative Analysis of Mining-induced Fractures Evolution and Application ResearchAbstract:
Quantitative analysis of the dynamic evolution characteristics of overburden fractures is particularly critical for the evaluation of mining damage. Taking 110903 working face of Renjiazhuang Coal Mine as the engineering background, the fractal dimension of cracks under different mining footage was calculated by using similar material simulation experiment, and the number, dip angle, length and width of cracks in overlying strata were analyzed, and the development and expansion of cracks in overlying strata were quantitatively studied. Under the same experimental conditions, the characteristics of fracture development before and after filling were compared and analyzed. The research results show that: (1) With the fracture of two key layers, the fractal dimension of overlying strata fractures presents a rising-stable-rising trend, and the change of fractal dimension is consistent with the change of peak pressure, which can reflect the change law of overlying strata migration and pressure appearance; (2) According to the evolution of cracks, the cracks in overlying strata of stope can be divided into cracks in abscission zone, cracks in compaction zone, cracks in caving zone, vertical fracture cracks on left and right sides, and cracks in abscission zone II. Among them, the distribution of fracture dip angle in vertical fracture zone is 0°~90°; The fractures in the caving zone are complex, the distribution of the dip angle of the fractures is 0°~360° and the fractures are well connected. The dip angle of fissures in the bedding area is nearly horizontal, and the connectivity of fissures is poor; (3) Through comparative experiments, it shows the law of crack propagation between unfilled and filled, which indicates that filling in caving zone in time during mining can effectively control the development of overburden cracks.
- 1
Study on the Relationship between the Width of Coal Pillar and the Deformation of the Bottom Drum of the Roadway along the Hollow Roadway Cutting Top and Unloading RressureAbstract:
In order to explore the influence of the width change of coal pillar in gob-side entry protection on the floor under the condition of lateral roof cutting, the mining roadway of a working face in Bojianghaizi Coal Mine was deeply studied through theoretical calculation, numerical simulation and field experiment, and the mechanical model of gob-side entry was built, and the analytical expressions of stress and displacement of the floor were obtained. FLAC3D was used to simulate the floor stress under different coal pillar widths. The results show that the floor stress of gob-side entry is asymmetrically distributed. With the increase of coal pillar width, the floor stress first increases and then decreases. When the coal pillar width is 10m, its peak stress reaches 51.28MPa. With the change of coal pillar width, the floor stress peak position gradually shifts from the solid coal side to the coal pillar side. With the increase of coal pillar width, the floor heave decreases gradually, and the increasing rate decreases gradually. The engineering results show that the lateral roof cutting, combined support and reinforcement of bottom corner control technology can effectively reduce the floor heave, improve the production efficiency and ensure the safety factor, which provides a reference for coal pillar width design in similar working conditions.
- 1
Numerical simulation of post-mixed abrasive water jet based on CFD-DEM coupling algorithmAbstract:
In order to more accurately simulate the mixing and flow of abrasive particles and water jet inside the post-mixing nozzle, this paper is based on a CFD-DEM coupled Euler-Lagrangian algorithm, computational fluid dynamics software Fluent and particle flow software EDEM were used to carry out co-simulation. The results show that the average velocity of the abrasive particles at the jet outlet is lower than the velocity of the water phase at the same position, and most of the abrasive particles collide with the inner wall and other particles after being impacted by the water jet, resulting in a large energy loss and multiple trajectories showing Bending. Only a few particles collide with the water jet, which are consistent with the direction of the water jet velocity, and are ejected at a speed close to the water phase. The CFD-DEM coupling algorithm can accurately simulate the mixing and flow of the post-mixed abrasive water jet, which can provide a better numerical calculation method for subsequent research and improvement of the post-mixed abrasive water jet.
- 1
Study on Constitutive Relation of Composite Rock Considering Temperature DamageAbstract:
In order to study the physical properties, mechanical properties and damage changes of the rock after temperature action, the composite rock samples were temperature treated. Six temperature gradients were set at room temperature, 60, 90, 120, 150 and 180 ℃, and the composite rock after temperature action was subjected to uniaxial compression tests. The Weibull distribution function is used to establish the computational damage constitutive model of composite rock series after temperature action, which is verified by the theoretical curve in the literature and the uniaxial compression results. The constitutive model is established based on Digital Image Correlation Technology (DIC). The improved constitutive model describes the failure characteristics of rock in the post peak stage more accurately, The results show that the theoretical curve of the composite rock damage model established after temperature action is in good agreement with the theoretical curve in the literature, and the model curve shows a high degree of similarity with the uniaxial test results. The constitutive model improved by DIC can better represent the characteristics of the failure stage of composite rock, indicating that the model established is reasonable and applicable.
- 1
Study on the Evolution of Temperature Field of Spontaneously Combustible Coal Gangue Hills Based on Teat PipeAbstract:
In view of the various hazards caused by spontaneous combustion of coal gangue hill, the passive cooling technology of heat pipe was used to treat it, and the internal temperature of coal gangue hill was monitored for one year, the cooling effect of spontaneously combusted coal gangue hill throughout the year is determined, the evolution trend of the internal temperature field was explored by means of isothermal map, and the seasonal characteristics of temperature change were analyzed. The results show that based on the passive cooling technology of heat pipe, the temperature of 81% of the monitoring points in the self-ignition coal gangue mountain is reduced to varying degrees, and the cooling range of more than 1/3 of the monitoring points reaches more than 100 °C, and the cooling effect is obvious. With the passage of time, the area occupied by high-temperature centers at different depth levels has been decreasing, and there is an evolutionary trend of continuous spread to low-temperature areas; The temperature change has obvious seasonal characteristics, the overall cooling efficiency is the highest in winter, the worst in summer, and the shallow layer is greatly affected by changes in the external environment, and the change characteristics with the seasons are deeper and more obvious.
- 1
Numerical Simulation Study on the Effect of Hollow Hole Aperture on Deep Rock Blasting Crack ExtensionAbstract:
Abstract：In order to address the problem of poor directionality of crack expansion between the shell hole and hollow hole in deep rock, the LS-DYNA finite element dynamic simulation software was used to study the influence of hollow hole diameter on rock stress distribution, inter-hole burst crack expansion and peak effective stress in the engineering background of 10204 cut top unloading along the hollow stay in Shanxi Yongning coal mine, and the field verification was conducted. The results show that: with the increase of hollow hole diameter, the maximum principal stress value and range increases, and the direction of the maximum principal stress does not change in the direction of the entire gun hole line, making the inter-hole crack expansion more directional; with the increase of hollow hole diameter, the inter-hole crack expansion length shows a rapid growth to a stable pattern; when the lateral pressure coefficient is less than 1, the increase of hollow hole diameter on the inter-hole effective stress effect is relatively When the lateral pressure coefficient is less than 1, the increase of the hollow hole diameter can effectively increase the peak effective stress at the inter-hole measurement point.
- 1
Study on surface movement and deformation law of shallow coal seam and stability of Tower FoundationAbstract:
There are a large number of high-voltage electrical towers on the surface of the mining area in northern Shaanxi. The mining of coal seams will cause the movement and deformation of high-voltage electrical towers, posing a threat to the safety of high-voltage transmission lines. Based on the theory of prediction of surface movement and deformation by probability integral, the law of surface movement and deformation and the stability of electrical towers are studied by using theoretical analysis, theoretical calculation and field measurement and other research methods. The research results show that: (1) The calculation formulas of the probability integral parameters of the base mining ratio Jc and the base loading ratio Jz are established. Both the surface subsidence and horizontal movement are negatively correlated with the base loading ratio and the base mining ratio. The inflection point distance is positively correlated with the base load ratio. (2) The calculation formula for the movement deformation of the mining high-voltage tower is established. The inclination deformation of the tower body depends on the surface inclination deformation and tower height, and the horizontal deformation of the foundation of the tower depends on the horizontal deformation of the surface and the root opening of the tower. , foundation properties and soil properties. (3) During the mining process of the 31104 working face of Jinjie Coal Mine in northern Shaanxi, the maximum inclined deformation expected by the tower Z219 is 92mm<450mm, and the maximum horizontal deformation is 4.15mm<4.55mm. The average deviation between the value and the measured value is 5.69%.
- 1
Research on the Technology and Platform of Collaborative Management and Control for the Whole Process of Metal Mine ProductionAbstract:
Under the background that metal mining enterprises have deeply carried out digitalization and information construction and made efforts to build first-class mines and intelligent mines, various software and hardware products for mine production technology and management have been developed and used. However, there are data islands, data gaps, system barriers and other problems between the software and hardware systems, which make it difficult to reflect the collaborative work effect of various production links. This paper focuses on the research and analysis of the collaborative management and control mode and implementation method among the production processes of mines, and designs the technology and platform for the collaborative management and control of the whole production process of metal mines. The platform is designed to realize digitization, automation and intelligence. Based on data standardization and construction standardization, optimize and upgrade the traditional process, intelligentize the existing equipment, develop relevant software and hardware systems, build mine data center, and form a collaborative management and control platform for the whole production process of metal mines. The platform is helpful to realize data integration and data sharing among various mine application systems, promote efficient collaboration between mine production technology and production management, improve modern management level of enterprises, and realize cost reduction and efficiency increase of mining enterprises.
- 1
Evolution Law of Displacement and Stability Analysis ofHigh and Steep Slope ExcavationAbstract:
In order to study the slope stability of high and steep rock slope under gradual excavation unloading, the displacement and slope stability coefficient are selected as evaluation indicators. Taking a granite mine as an engineering example, based on FLAC3D, the strength reduction method is adopted to design the excavation plan for each excavation unloading reduction section of 30m until the end of excavation unloading, and the final change plan for the side slope angle from 44° to 52° in 2° steps, Simulate the process of unloading step by step and leaning on the slope, reveal the displacement evolution law of the formation of high and steep slope and the change law of the slope stability coefficient, and determine the quantitative relationship between the slope stability coefficient and the maximum displacement and the slope height and the final excavation slope angle. The results show that the vertical displacement and horizontal displacement increase with the unloading stage, and the maximum vertical displacement and horizontal displacement increase in a quadratic function; With side mining, the final side slope angle increases, and the slope stability coefficient decreases from 1.93 to 1.60. The slope stability coefficient is negatively correlated with the end slope angle in a cubic function. The research results can provide some reference for the design and parameter optimization of high and steep rock mines, and provide a way of thinking for slope monitoring.
- 1
Constitutive relation of energy loss of rubber-tailings backfill under wet and dry cycleAbstract:
In order to explore the failure characteristics and energy evolution of rubber tailings backfill under the influence of wet-dry cycle, a test block of rubber tailings backfill was made, and the wet-dry cycle treatment, uniaxial compression test and scanning electron microscopy test were carried out on the rubber-tailings backfill. Based on the test results, the failure characteristics, energy evolution law and microscopic morphology of rubber-tailings backfill were explored. With the help of Weibull statistical distribution theory, the piecewise damage constitutive model of rubber-tailings backfill under the influence of wet-dry cycle was established. The results show that the number of wetting and drying cycles will cause the decomposition of the hydration products on the rubber surface, resulting in the reduction of the compressive strength and elastic modulus of the rubber-tailings backfill. At the peak stress of rubber-tailings backfill test block, the elastic energy is the main one, and the dissipative energy is the auxiliary one. The same is true at the end of the test, but the proportion of elastic energy is decreasing rapidly. The piecewise energy dissipation constitutive model of rubber filling block under the influence of wet-dry cycle is derived, and the fitting degree is high.
- 1
Study on Beneficiation Process of A Low Grade Refractory Oolitic Hematite Ore from YunnanAbstract:
In view of the fact that it is difficult to obtain qualified iron concentrate from a low-grade oolitic hematite ore in Yunnan by mineral processing, the nature of hematite aggregates containing a small amount of gangue minerals, and the characteristics between aggregates and gangue minerals are different and easy to be grinded and dissociated, a preliminary study on iron enrichment by mineral processing has been carried out. Compared with several mineral processing processes, it is concluded that both the single high intensity magnetic separation with stage grinding stage separation and high intensity magnetic-gravity separation process have the best separation index. The results showed that the two optimal processes obtained marketable iron concentrate containing 47.24% TFe and 69.74% TFe recovery, and iron concentrate containing 50.81% TFe and 46.01% TFe recovery (or iron concentrate with 48.71% TFe grade and 62.70% TFe recovery) respectively; The iron concentrate obtained from the two most suitable beneficiation processes can be consumed by blending with high-grade hematite concentrate in industrial applications such as iron concentrate smelting.
- 1
Mechanical analysis of deep vertical backfill pipeline under in-situ stressAbstract:
The vertical pipeline is the throat passage of deep mine backfilling. At present, only the internal pressure and abrasion margin of the pipeline are considered in the wall thickness design, but the high ground stress is not considered. In this paper, the stress state of vertical pipeline wall under three conditions of only internal backfilling slurry pressure, only external uniform ground stress and only external heterogeneous ground stress were analyzed respectively. The results show that the influence of the external ground stress on the stress state of the vertical pipe wall is more significant than that of the internal backfilling slurry pressure. The maximum stress value of the pipe wall is (3σhmax-σhmin), and the pipe wall stress increases linearly with the increase of the vertical pipe depth. Taking a copper mine as an example, the main cause of vertical pipe lining falling off is the extrusion of ground stress rather than the erosion of filling slurry. The calculation results show that the vertical filling pipe depth below 200 m in the copper mine is damaged because the wall thickness is not enough to resist the uneven ground stress, which is in good agreement with the actual observation results. Finally, a wall thickness design method of vertical pipeline considering in-situ stress is proposed, which can be used for reference in similar mines.
- 1
Study on Performance Degradation of Basalt Fiber Coal Gangue Concrete by TemperatureAbstract:
In order to study the mechanical properties and structural deterioration of basalt fiber coal gangue concrete (BFCGC) at different temperatures, this paper sets five temperature ranges from room temperature to 800 ℃, conducts high temperature tests, and analyzes the apparent characteristics, mass loss, mechanical strength and microstructure of BFCGC at different temperatures. The research shows that the apparent characteristics of concrete can indirectly reflect the deterioration trend of temperature. With the increase of temperature, the apparent damage degree of BFCGC at high temperature is gradually obvious, and the mass loss rate increases monotonously; The mechanical strength of BFCGC first increases and then decreases, and reaches the maximum at 200 ℃. The cube compressive strength, tensile strength and elastic modulus of BFCGC at 800 ℃ are 74.48%, 17.97% and 17.96% of those at room temperature, respectively; The performance change of concrete is mainly affected by temperature. The higher the temperature is, the worse the performance of concrete is. The addition of basalt fiber and activated coal gangue coarse aggregate can improve the high temperature resistance of concrete to a certain extent, but it is not enough to change the deterioration trend of temperature on concrete structure.
- 1
Research on harmful gas emission control and control technology of air shaft in non-coal mineAbstract:
In order to solve the problem that the concentration of NOx, SO2 and other toxic and harmful gases in the air pollution of the return air shaft is beyond the limit, this paper takes the west return air shaft of a mine as the engineering background, and puts forward a combined purification system of "activated carbon-CAO-SDA dry method". Through laboratory tests, the reaction principle of the system was clarified, and the curve relationship between activated carbon particle size, CO concentration and NO, SO2 concentration under different temperature conditions was obtained. The monitoring results show that: 1) the concentration of harmful gases such as NO and SO2 in the exhaust gas reaches the emission standard after purification treatment by the system; 2) There is an optimal coupling point between the gas concentration of NO and SO2, the particle size of activated carbon and the concentration of CO, and the purification efficiency of NO is the best at 1050℃.
- 1
Efficient Separation of High Sulfur Lead - Antimony - Zinc Polymetallics under Low Alkali ConditionAbstract:
Aiming at the problems of serious loss of antimony ore under high alkalinity, low concentrate grade under low alkalinity, mutual encapsulation and embedding among various minerals and high zinc and sulfur content in the separation of a complex and difficult high-sulfur lead-antimony ore in Hechi, Guangxi, a new type of inhibitor WH90 and zinc sulfate of pyrite were used as inhibitors under low alkalinity conditions, Pb(NO3)2 was used as the activator of stibnite, and diethyldithiocarbamate was used as the collector of lead-antimony to achieve efficient separation of lead-antimony and zinc-sulfur. The new collector CZ-08 using zinc in the zinc-sulfur separation process is cheaper and more efficient than other commonly used collectors.The lead content in the raw ore is 1.12%, the antimony content is 2.70%, and the zinc content is 3.91%. Lead and antimony mainly exist in stibnite and jamesonite, and zinc mainly exists in the form of sphalerite. The lead-antimony concentrate obtained by laboratory small closed-circuit test contains Pb16.35% and Sb41.76%, and the recovery rates of lead and antimony are 88.66% and 94.24%, respectively. Zinc concentrate contains Zn 61.44%, recovery 84.87%.
- 1
Research and development of non-contact speed measurement technology for mining transportation equipmentAbstract:
The speed and acceleration of vehicles are important safety technical indicators to measure the mining transportation equipment. Based on the principle of Doppler speed measurement, DSP digital signal processing technology and ARM embedded technology, an on-board non-contact speed measurement device is developed by adopting the improved Burg algorithm and QWT software technology, which can effectively ensure the real-time and accurate measurement of transportation equipment. The experimental verification shows that the speed measuring range of the device is 10m / s, the accuracy is ± 0.1 m/ s, and the acceleration measuring accuracy is 0.05m/s2.
- 1
Influence of Compaction Degree on Ore Drawing Effect of Non-pillar Sublevel CavingAbstract:
Non-pillar sublevel caving method is widely used because of its advantages of low production cost, simple structure and high safety. However, the ore drawing work of this method is carried out under the condition of loose rock cover. The dispersion of caving rock is subject to blasting and the extrusion of overlying cover rock, resulting in different compactness, and the different thickness of overlying rock leads to different compaction degree of the lower ore, which affects the ore drawing effect in the process of ore drawing. In order to study the influence of compactness on the ore drawing effect of pillarless sublevel caving method, the ore drawing effect of different compacting degree is studied by using a single sublevel and single route physical ore drawing model The results show that the amount of released pure ore , the cumulative waste rock mixing rate and the ore recovery rate change regularly with the decrease of compactness. Appropriately changing the compactness of the ore, the structure between the particles will be improved in the form that is conducive to ore drawing, increasing the output of pure ore, reducing the amount of waste rock mixing, and improving the recovery rate of ore.
- 1
Prediction Model of Pressure Drop in Backfilling Slurry Conveying Based on Semi-Industrial Ring-tube ExperimentAbstract:
Backfill mining method is the main method to ensure the safety mining of deep mineral resources. The scientific layout of backfilling pipeline in the design of backfilling technology system is the main difficulty. Only accurately grasp the situation of the pressure drop of backfilling slurry, in order to carry on the reasonable backfilling pipe network layout design. The traditional data of slurry pressure drop are obtained by semi-industrial ring-tube experiment, which have some problems such as large amount of labor, low efficiency and limited data. In this paper, the random forest machine learning algorithm is used to analyze and model the data of the loop pipe experiment, and to predict the pressure drop of the conveying, it is proved that the model of stochastic forest algorithm is feasible to predict the pressure drop and can be used to assist the backfilling process design.
- 1
Study on mechanical characteristics and microstructure of aluminum slag modified eco-concreteAbstract:
In the process of bauxite mining, a large amount of solid waste residue is produced. In order to solve the problem of discharge and accumulation of bauxite waste residue and promote the recycling of solid waste resources, the modified concrete was prepared by adding different amounts of bauxite waste residue to mortar. Uniaxial compression test, computed tomography (CT) scanning test and scanning electron microscopy test were carried out to investigate the compression characteristics and microstructure of iron-doped aluminum slag concrete. The results show that the compressive strength and elastic modulus of the concrete doped with iron and aluminum slag increase first and then decrease with the increase of the content. When the content of iron and aluminum slag is 15%, the strength of the specimen is the highest. The two-dimensional image of concrete mesostructure was obtained by CT scanning. It was found that with the increase of iron and aluminum slag content, the number and size of pores in the specimen gradually decreased, and the concrete porosity calculated by CT image maintained a negative linear relationship with the compressive strength. The doping modification of iron and aluminum slag promotes the secondary hydration reaction of cement, causing the content of Ca(OH)2 in cement mortar to decrease, the content of calcium silicate hydrate to increase, and then the crack between aggregates to close, and the mechanical properties of concrete to improve.
- 1
Practice of Controling Stage Flow to Eliminate Ore Detention in deep chuteAbstract:
Abstract:According to the factor analysis of the conditions of the bonded arch in the process of the deep slip ore flow, the compaction of the stage flow and the negative pressure state in the well weaken the disturbance of the air disturbance to the temporary balance arch, which is the main cause of the blockage of the deep slip well.It is proposed that through the control of the weakening flow of the bottom and compaction of the lower ore and the strengthening flow disturbance.It is proposed based on stage flow control Specific ways and methods of prevention: that is, once the ore retention in the well occurs, immediately stop the mine, using intermittent forced mine outlet method, to create a new stage in the lower storage section to produce strong air disturbance in the well slip cavity, so as to achieve the purpose of destroying the temporary balance arch.Through years of practical application, this method can timely eliminate the retention of ore in the well bore, safely and effectively prevent the black ditch main well bore blockage accident, thus further confirming the scientific nature of the basic cause of deep slip well bore blockage.
- 1
Study on the Characteristics of Coupled Gas Thermal-Fluid-Solid Extraction Based on Coal Body AnisotropyAbstract:
In order to study the relevant characteristics of gas extraction under the influence of coal seam permeability anisotropy, and to consider the influence of temperature change on gas seepage and coal deformation, a coupled thermo-fluidsolid model of coal rock deformation field, seepage field and temperature field was established. The simulations were solved using COMSOL Multiphysics software to study the influence of initial permeability, initial coal seam temperature and initial gas pressure on the effective extraction area, and the results are of some significance for gas extraction. The study shows that: considering the anisotropy of permeability, the area around the borehole shows an elliptical pressure drop, which spreads into a drum shape with the increase of extraction time and redistributes the stress around the borehole. The gas seepage rate in the area with larger permeability is fast, corresponding to high extraction efficiency. The temperature of the coal seam decreases continuously with the extraction process until it stabilizes, and the temperature is highest at the farthest point from the borehole, and the larger the initial temperature of the coal seam, the smaller the effective extraction area. The higher the initial pressure, the longer the desorption time of adsorbed gas and the lower the effective extraction area.
- 1
Coal Block Detection Algorithm Based on Recursive Gated Convolution and Contextual AttentionAbstract:
Aiming at the problems of low detection accuracy caused by missed detection and false detection due to uneven illumination of coal block detection on coal mine belt conveyors, an improved yolov5s coal block detection algorithm based on gated convolution and contextual attention mechanism is proposed. First, the residual module in the backbone network is replaced with a recursive gated convolution module, and the feature extraction capability of the model is enhanced by gradually fusing feature information to extract high-order semantic features. Secondly, the GCA attention mechanism is added to the feature fusion structure, the global context information is integrated into the coordinate attention module, the global representation of the region of interest is strengthened, the multi-scale feature fusion ability is enhanced, and the model"s sensitivity to coal edge features is improved. Finally, the SIoU loss function is adopted to accelerate the convergence of the network model. The experimental results show that the average precision of the improved algorithm on the self-built coal block data set reaches 92.8%, the recall rate reaches 85.9%, and the detection speed reaches 38 frames/s. It not only improves the detection accuracy, but also satisfies the real-time detection.
- 1
Quantitative characterization of granite thermal damage at 700℃ by nuclear magnetic resonanceAbstract:
The physical characteristics of the rock mass under the action of high temperature will change significantly, and the pore structure evolution and wave velocity decay characteristics of granite under different high temperatures are studied by means of nondestructive monitoring such as nuclear magnetic resonance technology, the results show that with the gradual increase of temperature, the NMR(Nuclear Magnetic Resonance) T2 relaxation time span, T2 spectral area and NMR signal intensity of the granite sample are gradually increasing, the number of pores which among different pore diameters increases, and total volume increases. The temperature of granite with obvious thermal damage is about 500 °C. Before 500 °C, the pore size and number of internal pores do not change significantly, and the transformation between pores with different pore sizes is mainly. After 500 °C, the internal porosity of the rock increases significantly. Among them, the newly added pore volume is the main one. Aiming to quantitatively characterize the damage degree of high temperature to granite, a theoretical model of thermal damage of granite under different high temperature thermal action was established with the help of porosity, thermal damage factor and other parameters, which has certain reference value for deep formation projects involving high temperature rock mass.
- 1
Simulation Experiment Research on the Shape and External Flow Field of Spiral Concrete SprinklerAbstract:
In order to explore the influence of the geometric structure of the shotcrete nozzle on its internal and external flow fields, combined with the ANSYS Fluent simulation software, with the diameter of the aggregate part, the length of the aggregate part, and the length of the diameter change section as independent variables, the numerical simulation analysis of each phase in a spiral nozzle was carried out, and the velocity vector diagram, velocity cloud diagram, and velocity curve diagram of the fluid domain section were obtained. The analysis shows that the water flow at the high-pressure water inlet of the spiral nozzle is divided into two parts, one part is mixed with wet materials to increase the fluid velocity, and the other part flows along the pipe wall to wash the pipe wall to reduce pipe plugging; With the increase of the diameter of the aggregate part of the sprinkler head, the outlet velocity of the aggregate is linearly negatively related to the diameter of the aggregate part. The outlet velocity of the aggregate gradually decreases, and the gravity has greater influence on the aggregate flow field. The velocity gradient of the aggregate flow field in the external flow field from the core area to the edge of the aggregate flow field tends to be gentle, and the attenuation of the velocity of the aggregate on the axis tends to be gentle; When the diameter of the material gathering part of the nozzle remains unchanged, the concentration in the central area of the external flow field also tends to increase with the increase of the length of the material gathering part. When the length of the material gathering part of the nozzle is 40 mm, 100 mm and 150 mm respectively, there is no obvious difference in the velocity uniformity at the outlet of the nozzle, which is more uniform than the outlet velocity when the length of the material gathering section is 0 mm; Increasing the length of the nozzle diameter change section can obtain greater outlet velocity, so that the aggregate flow field can be more concentrated and better aggregate effect can be achieved. At the same time, the axial velocity attenuation of the aggregate external flow field increases with the increase of the diameter change section.
- 1
Evaluation Model and Application of Safe coal quantity Multiple Values in coal enterprisesAbstract:
The change of gas management concept from passive to active in coal enterprises is of great significance for promoting coal resources from reserves to safe coal quantity and realizing the value of gas management work. In order to promote coal enterprises continue to increase investment in gas control actively, improve the efficiency of gas control, from the economic, ecological, safe production three dimension defines the pluralistic value of safe coal, using different valuation methods, building security coal multiple values evaluation model, and applies the model to Shanxi Lu’an Chemical Group Company. The results show that the model can quantify the total value of safe coal quantity, and then drive the gas control work of coal enterprises from passive need to active creation.
- 1
Effect of Fracture Location on Mechanical Properties of Composite Rock Samples under Different Confining PressuresAbstract:
In order to study the effect of fractures in different strata on mechanical properties of laminated composite rock under complex confining pressure environment. Particle flow software PFC2D was adopted to establish a numerical model of composite rock samples with prefabricated single fracture, and then the influences of fracture positions on the stress-strain, volume change and related stress threshold of the samples under different confining pressures were analyzed. The results demonstrated that :(1) As the confining pressure increased, the failure characteristics of rock samples changed from being dominated by the location of fractures to being dominated by confining pressure. (2) When the confining pressure remained constant, with the change of fracture positions in soft rock, joint surface and hard rock, the duration of the expansion and deformation of the rock samples was obviously prolonged, the amount of deformation increased significantly and the dilatancy strength somewhat weakened. (3) With the increase of confining pressure, the strength of rock enhanced, however, the existence of fractures would obviously weaken the strength of rock. When the fractures were in the hard rock, the degree of weakening was the lowest. (4) When fractures existed in soft rock, at the junction and in hard rock, the stress threshold of the corresponding samples would be able to increase sequentially. With the increase of confining pressure, the influence of fracture positions on the variation law of fracture initiation stress was dominant, but the influence on the variation law of damage stress and peak stress was weakened. The research results were instructive for practical engineering construction and design.
- 1
Comparative Experimental Study on Mineral Processing of a high sulfur lead-zinc ore in Yunnan.ChihongTechnologyEngineeringCo.
Abstract:
A high sulfur lead zinc ore contains Pb 5.23%, Zn 15.40%, and S 24.86%. The lead oxidation rate is 3.05%, and the zinc oxidation rate is 0.43%. It belongs to a high sulfur sulfide lead zinc ore. Since the establishment of the plant, the beneficiation process adopted by concentrator is zinc floating ". The problems such as high zinc content in sulfur concentrate is existing in the existing process flow. In order to reduce the zinc content of the sulfur concentrate and improve the beneficiation index further, comparative tests were carried out between the two different flow schemes, “mixed flotation of lead and sulfur, separation of lead and sulfur - zinc floating test indexes is better and the reagent cost is lower and the output value of concentrate is higher of the flow schemes With the raw ore containing Pb 5.34%, Zn 15.59% and S 26.18%, the lead concentrate containing Pb 61.64%, Zn 3.37% and S 20.15%, and the recovery rate of Pb is 89.34% ; and the zinc concentrate containing Zn 51.54%, Pb 0.59%, S 35.15%, and the recovery rate of Zn is 96.88%; and the sulfur concentrate containing Pb 0.53%, Zn 0.36%, S 47.91%, and the recovery rate of S is 49.79% are obtained through closed circuit test of the process of "sequential preferential flotation of lead, zinc and sulfur". Then the low alkali beneficiation process of high sulfur lead zinc ore is realized, and the process of "sequential preferential flotation of lead, zinc and sulfur" is recommended to adopt on site.
- 1
Similar Simulation Experiment of Cemented Waste Rock Backfill and Its Anisotropic Strength DistributionAbstract:
Cemented waste rock backfill can effectively treat mined-out areas caused by sublevel open stoping with subsequent filling stope regarding to medium thick orebody, but its application is limited by the heterogeneity of spatial distribution of backfill strength in stope and the difficulty of detection. Taking waste rock, cement and water as filling materials, the rock cemented filling ratio test and similarity simulation test were carried out, and the surface response method was used to analyze the spatial distribution characteristics of the similar model backfill. The results show that the best ratio is water cement ratio 1.5, cement waste rock ratio 1:10, designed backfill strength on 28th day R28=2.2 MPa. In the similar model, the heterogeneity of backfill strength is high around and low in the middle, and the "backfill shell" with high strength is formed in two sides of the stope and the backfill integrity is improved. In addition, based on the similar simulation test, the research and application of direct-irrigation cemented waste rock backfill technology are carried out, and it is found that -150 mm full grain waste rock + cement slurry direct-irrigation waste rock cemented backfilling is conducive to safe mining of broken medium and thick gold orebodies.
- 1
Comparison and Application of Different Types of Water Retaining Agents for Cd2+ AdsorptionAbstract:
The adsorption effects of PAM( Polyacrylamide) and PAA(Polyacrylic acid) on Cd2+ in the environment were investigated, the experimental results are as follows:(1) Reaction time and pH were the main factors affecting the adsorption effect of PAM. The optimal reaction time was 0.5 h and pH was 7. The main influencing factors of PAA are the addition amount and water content, and the optimal addition amount is 0.3 g/10 g, and the water and soil ratio is 10:1.(2) The results of PAM and PAA orthogonal experiment are slightly different from the results of single factor experiment. The optimal conditions of PAM orthogonal experiment adsorption are: dosage of 0.05 g/10 g, Cd2+ concentration of 0.25 g/L, adsorption time of 3h. PAA: the dosage is 0.15 g/10 g, the concentration of Cd2+ is 0.1 g /L, and the adsorption time is 1h.(3) From the analysis of the experimental results, PAM is more suitable than PAA for the treatment of soil heavy metal pollution in Zhundong arid mining area, and the optimal amount of PAM is 0.05 g/10 g. By comparing the adsorption of two kinds of water retaining agents on Cd2+ in different environments, we can understand the action properties of different types of water retaining agents, and provide a reference for the remediation of soil heavy metal pollution in arid mining areas.
- 1
Experimental Study on the Formula of New Cement Material for an Iron MineAbstract:
A certain iron mine is faced with the problems of low strength and high cost of backfill after changing from open-pit mining to underground mining, so it is urgent to develop a new high-efficient cement material to improve the strength of backfill. In order to meet the requirements of mining, experimental study on the formula of new cement material was carried out on the basis of different slag wastes around the mine. Firstly, the particle size and chemical composition of tailings were determined by PSD and XRF to determine the suitability of tailings as filling aggregate; Secondly, based on the theory of orthogonal experimental design, the results of 7-day and 28-day strength were analyzed by range analysis and regression analysis, and the optimal formula and regression equation were obtained. Finally, the reaction mechanism of the new cement material was obtained by SEM analysis. The results show that the optimum ratio of the new cementitious material is Slag: Gypsum: Lime: Clinker = 65:25:5:5.
- 1
Design and Numerical Simulation of a New Jet Bubble GeneratorAbstract:
In order to improve the mineralization effect of fine-grained minerals, a new bubble generator with oscillating cavity is designed, and the idea that two-phase flow can realize supersonic flow at low velocity is introduced into it. Through theoretical calculation, the critical value of supersonic flow of gas-liquid two-phase mixture is 20m/s under the condition of working pressure of 0.1MPa and gas-liquid volume ratio of 1:1. Then, the new bubble generator is numerically simulated by Fluent software, and the velocity and volume distribution law of its internal fluid is obtained. The simulation results show that the highest velocity of liquid phase is 20.7m/s and the highest velocity of gas phase is 24.2m/s, but only when the gas holdup reaches about 50%, the shock wave oscillation can occur at the end of the diffuser. This shows that the supersonic flow of gas-liquid two-phase flow is not only related to velocity, but also to the ratio between them, and both of them are indispensable. In the process of supersonic flow, there will be a shock wave, which can form a turbulent flow with high energy, so that the gas phase and the liquid phase can be fully mixed, thus improving the mineralization effect.
- 1
Quantitative Identification of Cracks in Jointed Layered Rock Specimens under Uniaxial CompressionAbstract:
To study the crack propagation mechanism and failure mode in composite rock strata under uniaxial compression, the digital image correlation method(DIC) was used to observe the crack strike and strain field changes of rock-like specimens with a prefabricated joint under uniaxial compression. The covariance matrix was introduced to quantify the strain field dispersion of specimens with joint dip angles α=0°,15°,30°,45°,60°, and 75°. After analysis, the following results were obtained: The new method was used to quantify the displacement data of the two sides of the crack, and the crack types were identified as tensile crack (Type I), shear crack (Type II), and composite tension-shear crack (Type I-II); The parameter V obtained based on the covariance matrix can characterize the crack initiation and propagation process; According to the growth rate of V, the crack types were identified as tensile crack (0.12×10-4~0.49×10-4), shear crack (1.17×10-4~4.5×10-4), and composite tension-shear crack (0.72×10-4~0.99×10-4).
- 1
Research on vibration characteristics of cantilever type falling dangerous rock massAbstract:
The stability of the cantilevered falling dangerous rock mass is controlled by the depth of the trailing edge fissure. How to judge the current fissure depth cannot be solved by statics. The cantilevered falling dangerous rock mass is generalized as a cantilever beam model, the dynamic equation of the rock beam is established based on the modified Timoshenko beam theory, and the boundary constraints and damping conditions of the rock beam are analyzed in depth with the dynamic basic half-space theory, and different fracture depths are obtained. Analytical algorithm for natural frequencies of dangerous rock masses under conditions. The rationality of the algorithm is verified through indoor experiments, and the conclusions are drawn: (1) The natural frequency of dangerous rock mass is negatively correlated with the crack depth of the trailing edge, and the two are one-to-one correspondence. The crack depth can be inversely calculated according to the natural frequency value. (2) The calculation results of this algorithm are in good agreement with the laboratory test results, which fully demonstrates the rationality of the algorithm. This algorithm can realize the quantitative calculation of the natural frequency of different fracture depths of the dangerous rock mass, and provide a theoretical basis for the monitoring and early warning of slope collapse.
- 1
Study on strength damage and energy dissipation of gangue aggregate concrete under early loading and curingAbstract:
In order to study the influence of early age loading and curing on the strength evolution of gangue aggregate concrete, the gangue aggregate concrete specimens were loaded and cured with different stress-strength ratios at 7 days, and the uniaxial compression test was carried out at 28 days. At the same time, the acoustic emission (AE) ringing changes of the specimens during loading were monitored, and the microstructure of the specimens was observed by scanning electron microscope (SEM). The strength damage and energy dissipation law of gangue aggregate concrete under early loading and curing were explored. The results showed that the early bearing of 50% – 70% stress-strength ratio of could promote the improvement of the later strength of the gangue aggregate concrete, when the stress-strength ratio exceeded 70%, the gangue aggregate concrete showed the deterioration effect. The uniaxial compression process of specimens with different stress-strength ratios during early loading and curing showed different energy dissipation characteristics. When near the peak stress, the accumulated energy in the specimens suddenly released sharply, and the detected acoustic emission signal intensity would surge to the peak. The damage evolution of the gangue aggregate concrete can be regarded as the fracture process of the hinged bond in the structural model, and the early certain load could promote the improvement of the self-healing ability of gangue aggregate concrete.
- 1
WEI Ligang1,2, ZHANG Hui3, LI Guosheng3Abstract:
The use of prestressed anchor cable anchor injection technology is an effective way to solve the stress type bottom drum of the roadway. The anchor strength of existing anchor materials, etc. cannot meet the construction requirements, so improving the mechanical properties of anchor materials is the research focus of the bottom drum management technology. In view of the obvious effect of metakaolin on improving the working performance of non-shrink grout, the chemical effect of different ratios of metakaolin on high-strength non-shrink grout was studied, and the effects of conditions such as water absorption, porosity, setting time and acidity on its compressive strength were analyzed. The results show that the composite base plate anchorage material has better water absorption and porosity; the composite material has better corrosion resistance to alkaline solution than to acidic solution; the best effect of improving the performance of the grout is achieved when the amount of metakaolin is 0.3% and the water-cement ratio is 0.2, and the 28d compressive strength reaches 88.05Mpa, which increases 25.73% compared with no addition of metakaolin, and this study It has important guiding significance for the development of anchoring materials for roadway bottom slabs.
- 1
STUDY ON THE INFLUENCE OF COAL PARTICLE SIZE ON GAS CONTENT IN COAL SEAMAbstract:
In order to explore the response mechanism of coal seam gas content to the change of pulverized coal particle size, Coal from Yangquan 13# coal seam was selected and prepared into seven different grains of 0.17~0.28 mm, 0.28~0.8 mm, 0.8~1 mm, 1~3 mm, 3~5 mm, 5~6 mm and 6~10 mm. The isothermal gas desorption/adsorption experiments of coal under different particle sizes were carried out, the influence of particle size on coal seam gas content was analyzed, and a mathematical model between coal seam gas content and average particle size was constructed. The results show that the gas content in coal seam decreases significantly first and then increases slowly with the increase of particle size. The growth trend of gas content is opposite on both sides when the average particle size is 2.6mm. The coal gas content grows slowly and tends to a constant value when the average particle size increases to 6mm. The limit particle size exists in 6.8mm. The gas content of coal with different particle sizes can be accurately predicted by above model between gas content and average particle size.
- 1
Study on mechanical properties and brittleness index of water-cooled graniteAbstract:
In order to study the relevant physical and mechanical properties and brittleness indexes of granite after water cooling at different high temperatures, uniaxial compression tests and acoustic damage tests were carried out on granite samples after water cooling at 200 ℃ ~ 800 ℃. The variation rules of mass loss rate, porosity, acoustic wave velocity and uniaxial compressive strength with temperature were investigated, and the brittleness index based on initiation stress and damage stress was established. The results show that the mass loss rate of granite increases with the increase of temperature, and the change of porosity is proportional to the change of temperature. It is found that 400 ℃ is the critical point for the sharp increase of porosity, and the acoustic wave velocity decreases with the increase of temperature. the uniaxial compressive strength of granite decreases with the increase of temperature, and 600 ℃ is the threshold for the deterioration of compressive strength of granite after thermal shock. The brittleness of granite after high temperature water cooling is analyzed, and the test results are consistent with the stress-strain curve and fracture form of granite. the brittleness of granite decreases and the ductility increases with the increase of temperature. This study is of great significance to the instability in the development of dry and hot rocks and the establishment of underground thermal reservoirs.
- 1
Numerical Simulation Study on Dust Concentration of Dump Truck Driving in Open Pit MineAbstract:
In order to accurately describe the dust production and transportation mechanism of road transportation in open-pit mines and reveal the dust law of dump trucks. Through the establishment of geometric model, the discrete term model numerical simulation method and dynamic grid technology are used to simulate the distribution characteristics of air flow and dust around the body of dump truck at different speeds. The results show that the height and concentration of dust increase with the increase of the speed of dump truck. The higher the vehicle speed, the greater the dust concentration at the rear of the vehicle. When the vehicle speed reaches 40 km/h, the road dust concentration reaches 362 mg/m3. Different dust particle sizes have a certain impact on the rear dust concentration. The dust concentration increases with the decrease of particle size, and the average dust particle size is 1 μm, the dust concentration is the highest. The dust concentration is different under different mass flow rates. The greater the thickness of ground dust, the greater the dust concentration.
- 1
Development of VR System for Mine Fire Escape and Research on Psychological Load of PersonnelAbstract:
In order to study the difference in individual psychological load in the scene of mine fire, a VR system with teaching modules and fire escape modules and operated with HTC VIVE equipment was developed based on tools such as 3Dmax and Unity3d, and the simulation escape experiment was carried out, learn about the personality type of participants through the Eysenck Personality Questionnaire, Physiological Signal Monitoring System (PhysioLAB) is used to monitor the heart rate, skin electricity, skin temperature and respiratory rate of participants in resting states and stress states, and to apply SPSS 20.0 software to significantly test the physiological index values before and after the stimulus; The K-means fuzzy clustering algorithm was used to explore the difference in psychological load before and after stress in participants of the two personality types, and the stress response level index (F-value) was introduced to quantify the stress response level in the context of individual mine fire. The results show that compared with the rest period, under the scenario of sudden fire in the mine, the physiological signal changes of the participants meet the criteria of significance in statistics, and the change of skin electrical index is the largest, and the change of skin temperature index is the smallest. The psychological load of the emotional personality participants was higher than that of the stable personality participants, and the stress response level was weaker than that of the stable participants.
- 1
Numerical simulation of thermal damage and fracture of rockAbstract:
Numerical simulation of discontinuous phenomena such as rock cracking and separation using discrete element method is an important tool to reveal the cumulative damage and destruction of fine and microscopic media under complex conditions. In this paper, we establish a thermodynamic coupled mathematical model based on the particle flow discrete element program PFC2D, and carry out a simulation study for the expansion evolution law of damage cracks in granite under the effect of temperature. The numerical model calculation results show that: the cracks in the numerical model under thermal shock all start from the surrounding area to the inside, and produce relatively dense cracks at the boundary; the process of heating and cooling will cause some thermal damage to the rock, and the cracks are all first to appear between the particles with larger thermal expansion coefficient, and 400℃ is the crack initiation temperature of this rock species; the mechanical properties of the main cracks produced in the process of heating and cooling are different respectively. The cooling causes a small enhancement followed by a large deterioration of its macroscopic mechanical properties, and the mechanical properties decay by 42%. The calculated results maintain a good agreement with the experimental phenomena.
- 1
Evolution Law of Rock Fracture under Coupling of Regionalized Structure and FractureAbstract:
Under uniaxial compression, the evolution of regionalized structure in rock leads to fracture, and fracture also interacts with regionalized structure. In order to study the evolution law of rock fracture under coupling of the two. The acoustic emission-acoustic imaging monitoring is used to obtain the wave velocity data inside the rock, which are connected with the particle flow program. According to the evolution behavior of the regional structure in the loading process, the model is optimized, and to study the evolution law of rock fracture under coupling of regional structure and fracture. The results show that (1) The dynamic evolution model is constructed by the modeling method in this paper, and the fracture morphology has good similarity with the laboratory test. (2) In time, the crack initiates in the degradation evolution stage of the localized structure, and in space, the crack initiates in the interior of the degraded type III localized structure. (3) When the regionalized structure is strengthened and evolved, the cracks mostly expand at the boundary, and gather and nucleation in the region with weak mechanical properties. When the regionalized structure continues to deteriorate and evolve, the cracks converge into crack bands, and propagate in the evolution direction near the boundary.
- 1
Density Functional based Tight Binding (DFTB+) Study on Surface Sulfidization and Adsorption of Xanthate on Cerussite SurfaceAbstract:
Sulfidization-xanthate method is the most important method for cerussite flotation. The surface structure of cerussite could be changed by sulfidization to affect flotation. In this paper, the Density Functional based Tight-Blinding (DFTB+) method was used to simulate the adsorption of ethyl xanthate, propyl xanthate and butyl xanthate on the cerussite (001) surface. The calculation results indicate that the three kinds of xanthate collectors could chemically adsorb on the cerussite (001) surface, and the adsorption is stronger with the increase of the alkyl chains. Hydration could increase the adsorption distance of xanthate molecules on the surface, resulting in difficult adsorption between xanthate and hydrated cerussite (001) surface. After sulfidization, xanthate could adsorb on the cerussite (001) surface, and the adsorption strength is obviously enhanced. The research results can provide theoretical guidance for efficient flotation of cerussite.
- 1
Study on the Influence of Residual Coal Pillar Concentration Stress on Mining of Upper Protective LayerAbstract:
In order to study the influence of the residual coal column mined in the upper protective layer of Pingmei Liu mine on the recovery of the protected layer, the influence range and limit strength of the residual coal column, the stress distribution of the coal column, the gas parameters in the coal column impact area and the pressure relief protection area were studied by combining theoretical analysis, numerical simulation and on-site measurement. The results show that the influence range of the residual coal column is 8.5m and the ultimate strength is 25.9Mpa, the stress peak within the tendency range of the coal column is directly below the centerline of the residual coal column, which is 83.2 Mpa, and the stress concentration coefficient is 3.5; the stress concentration in the influence zone of the coal column after the collapse of the coal column is not obvious, and the residual coal column becomes smaller than the height of the original coal column, accounting for 54% of the height of the original coal column. The difference between the S value of the drilling chip amount in the coal column impact zone and the pressure relief protection area and the q value of the initial velocity of the drilled gas gushing out is very small, and the gas release rate in the coal column impact zone is more than 50%. The protection effect within the range of the remaining coal column of the protective layer mining is continuous in the tendency, and the impact on the recovery of the working surface of the protected layer is small.
- 1
Experimental study on static and dynamic flocculation and sedimentation law of medium fine tailingsAbstract:
Aiming at the problem of slow settling speed of medium fine total tailings,In order to explore the flocculation and sedimentation law of medium and fine-grained full tailings under the coupling conditions of feed rate, sedimentation rate of sludge layer,underflow mass concentration and yield stress.Static flocculation sedimentation experiments were carried out with a 1000ml glass measuring cylinder,A self-developed continuous thickening test system was used to simulate the dynamic flocculation and sedimentation process of a vertical sand bin under flocculation conditions.The result analysis shows that:The shape of flocculation sedimentation curve drawn by static flocculation sedimentation is basically the same, It shows a rapid decline first and then basically tends to the level;The underflow mass concentration is the highest when the feed rate is 0.6t/(m2·h);It has a positive correlation with the underflow yield stress and a negative correlation with the sedimentation rate of the mud layer, and increases with the increase of the feeding rate;After the flocs pass through the turbulent zone, the law of accelerated sedimentation first and then stable sedimentation appears.And guided the industrial application of vertical sand bin flocculation and thickening of medium and fine tailings in this mine.
- 1
Numerical simulation of Stope structural Parameters in large diameter deep hole Caving with Subsequent filling mining processAbstract:
Reasonable room structure parameters are the key to realize safe and efficient mining of ore body by large diameter deep hole caving with subsequent filling mining technology.S In view of the actual room layout and mining situation of a mine, a THREE-DIMENSIONAL model is established. FLAC3D is used to carry out numerical simulation calculation of two different filling ratio schemes, and the stress field, plastic zone and displacement field of each scheme are analyzed. Combined with the analysis results, it is indicated that the filling ratio has certain optimization space while ensuring stability and safety.S Secondly, the numerical simulation analysis is carried out on the way of arranging the roadway stoping two-step ore room in the original backfill. It can be seen that the tunnel excavation will lead to the rapid expansion of plastic deformation inside the backfill, which will lead to adverse engineering phenomena such as roof caving and collapse.S According to the analysis results, the bottom structure of the two-step stope is designed and optimized, which fully guarantees the safety and reliability of stope stope.
- 1
Analysis on Blocking Effect of Mineral Powder on Tubular Sampling Drill Rod of Copper Concentrate Powder Sampling MachineAbstract:
The copper concentrate powder sampling machine is the key equipment of the external mineral powder automatic sampling machine in non-ferrous metallurgy enterprises. When the sampling drill rod is inserted into the material pile, due to the weight and extrusion of the mineral powder, a compacted mineral powder section will be formed at the front end of the drill rod. The compacted mineral powder section will prevent other mineral powder from entering the drill rod to form a powder plug effect, which directly affects the sampling effect of the sampling drill rod. This paper analyzes the causes of the powder plug caused by the drill rod inserted into the material pile, deduces the calculation formula of the powder plug length, establishes the discrete element model of the mineral powder particles, simulates and analyzes the drill rod sampling process, and draws the conclusion: when the drag coefficient is doubled, the plunger length is reduced from 96.4mm to 61.4mm, reduction rate 36%; the diameter of the drill rod is increased from 40mm After reaching 80mm, the plunger length L will increase from 96.4mm to 143.8mm, increasing rate 48%. Analyzing the influence of the powder blocking effect on the design of the structural parameters of the drill rod, and the inner diameter of the drill rod and the minimum length of the powder plug under the given parameters of the drill rod are calculated.
- 1
Thermal damage effect on strength and meso-structure of cemented backfill in high-temperature environmentAbstract:
In order to study the damage law of backfilling in high temperature environment, rock samples were heated at 0-500℃, and then uniaxial compression test, X-ray computed tomography (CT) scanning test and scanning electron microscope image were carried out to analyze the damage law of rock. The results show that the compressive strength and elastic modulus of sandstone gradually decrease with the increase of ambient temperature, and the decay rate is faster in the range of 0~300℃, and then gradually becomes slow. The two-dimensional CT images show that the number of pores and the size of main fractures increase rapidly due to high temperature impact. The porosity calculated from CT images is positively correlated with the ambient temperature in an exponential manner. Under the action of high temperature damage, the contact relationship between the expansion of internal pores and fractures and particles changes significantly, which is the fundamental mechanism leading to strength attenuation.
- 1
Study on Experimental Application of New Filling Material in a Lead-zinc MineAbstract:
In order to reduce the amount of filling cement in a lead-zinc mine to reduce the cost and fully digest the existing graded tailings in the mine, the filling additives suitable for the characteristics of the filling tailings of the mine were specially developed. Four kinds of filling additives, C606-1 ~ C606-4, were specially developed for the characteristics of filling materials in a lead-zinc mine. Through relevant matching tests, the better type C606-1 and type C606-3 additives were determined to be selected and used in further filling ratio tests Through the filling ratio test, it is finally determined that the developed filling additives can improve the compressive strength and flow performance of the filling body to a large extent, and reduce the cost of filling materials by more than 6.38%. The experimental results can provide a certain technical support for energy reduction and efficiency improvement of mine filling.
- 1
Study on The Influence of The Concentration of Sodium and Potassium Ions in Mine Water on The Atomization Characteristics of SprayAbstract:
Optimizing atomization characteristics is an effective method to improve the efficiency of mine atomization dust removal.In order to study the influence of the concentration of Na+and K+in mine water on its atomization characteristics and improve the effect of mine dust control, surface tension and atomization characteristics of different mine water were characterized by surface tension measuring instrument and laser particle size testing system, the surface tension difference caused by Na+ and K+ concentration in mine water and its influence on atomization characteristics were analyzed. The results show that the surface tension of mine water is positively correlated with its Na+ and K+ concentrations under the condition of low ion concentration. Under the same spray pressure, the droplet size is positively related to the surface tension, and reducing the surface tension of mine water can improve the dust reduction efficiency. The decrease of surface tension can extend the distribution range of atomization area and extend the dust collection range, and increase the amount of dust deposition;?The droplet size in the fog field gradually presents a uniform distribution with the decrease of surface tension, which is conducive to improving the wetting ability of the droplets to the dust.The research results have positive significance for optimizing the atomization characteristics of spray, improving the efficiency of spray dust reduction and promoting the management of mine water resources.
- 1
The law of the head-on rock pressure behavior and the mechanism of the roof instability in the gob area in the coal roadway with thin layer roofAbstract:
The huge consumption of coal roadway is determined by the coal occurrence characteristics and the mining system in China., the unreasonable selection of construction parameters of coal roadway is easy to increase the risk of roof caving and reduce the speed of roadway formation in the tunneling operation site (near the heading head). In order to solve the problem that "safety and efficiency are difficult to be unified" in the process of coal roadway driving, the rock pressure behavior law of surrounding rock near the heading of the rectangular section treasure layered roof coal roadway is systematically studied by means of theoretical analysis, numerical simulation and field test, and the deformation characteristics and instability mechanism of the roof in the empty roof at the heading are revealed. The research results show that the stress, deformation and failure of the roof under the influence of coal roadway tunneling start at a certain distance in front of the heading, and all have the characteristics of gradual evolution; The deflection of the underlying thin-layer rock plate in the empty roof area is asymmetric, and the tensile and shear actions are the root causes of its failure, the failure of the underlying rock layer will cause the failure of several thin-layer rock plates from bottom to top. As a criterion, the tensile strength of the lower thin rock plate does not exceed its internal force, and the limit empty top distance of coal roadway excavation under specific engineering geological conditions can be determined. Based on the limit empty top distance, combined with the engineering geological conditions and the original support scheme of 53152 return air roadway in Zhaozhuang Coalmine, the support scheme and construction procedure are optimized, and the field practice is carried out. The field statistics and monitoring results show that while the construction safety and the stability of the roof after excavation are ensured, the roadway forming speed is increased by about 25%.
- 1
Study on Energy Dissipation Characteristics and Damage of Rock under Cyclic ImpactAbstract:
In order to study the energy consumption characteristics and damage of basalt under cyclic impact, the SHPB system with confining pressure device was used to set up five impact pressure gradients to carry out Uniaxial Impact tests and cyclic impact tests under two confining pressure conditions on basalt samples. It is found that with the increase of the number of cycles, the absorption energy per unit volume of the sample increases slowly at a constant rate in the early stage, and increases sharply near the crushing. The greater the impact pressure is, the greater the unit volume absorption energy is, and the absorption energy per unit volume of basalt sample is positively correlated with the impact pressure. The application of confining pressure can greatly increase the ability of basalt to resist external impact, and the cumulative specific energy absorption value during crushing is about 10 times higher than that without confining pressure. With the increase of the number of cycles, the damage factor D first rises at a uniform speed, and then increases at an accelerated rate. When the rock is close to crushing, the energy absorption efficiency of the rock decreases, and the damage factor will tend to be stable. When the damage factor D reaches about 0.4, the basalt sample will have obvious shear cracks.
- 1
Development and Application Effect Evaluation of New Composite Slurry Spraying Technology SystemAbstract:
In this paper, a new composite spraying slurry with clay as the main base material and using water pressure and wind pressure to ensure intrinsic safety is proposed. Firstly, the air tightness, bending resistance and viscosity of the spraying material were measured in the laboratory; Secondly, the design, module combination and working condition parameters of the new composite slurry spraying system are studied; Finally, the new composite slurry spraying system is successfully applied to Dashui coal mine. The research shows that: (1) the new composite slurry spraying material made of clay: cement: additive: engineering fiber = 84:14:1.85:0.15 has good sealing and bending resistance and good adhesion; (2) The spraying distance of the new spraying system is about 1.5m, which is relatively good. Within 6m from the spraying port, the average value of total dust concentration is 0.2mg/m3; (3) The rebound rate of the new spraying process is 0.01%, which is 99% lower than that of the traditional spraying process, and the dust concentration on the operation site of the new spraying process is 15mg / m3, which is 93.3% lower than that of the traditional spraying process. The dust suppression effect of the new spraying process is good; (4) The new spraying process can effectively block the air leakage channel, shorten the width of the air leakage zone and inhibit the abnormal emission of gas and Co; (5) The powder flow rate and effective flow rate of the new spraying process are significantly lower than those of the traditional spraying process. Although this process can meet the basic operation efficiency requirements on site, there are still deficiencies in the spraying operation efficiency compared with the traditional spraying process.
- 1
Experimental Study on Dynamic Compressive Mechanical Properties and Failure Characteristics of Coal under Different Hydrostatic PressuresAbstract:
With the deepening of coal mining depth, the stress environment will gradually tend to the hydrostatic pressure state. In order to study the dynamic compressive mechanical characteristics of coal bodies in different hydrostatic environments, the dynamic compression mechanics of coal samples under load rates of 700-1400 GPa/S and three hydrostatic states (4MPa, 6MPa, 8MPa) were carried out by a split Hopkinson Pressure Bar(SHPB)system with hydrostatic confinement. The results show that the dynamic stress-strain curve has a short-term linear elastic stage. The dynamic elastic modulus and dynamic compressive strength are proportional to the loading rate and the hydrostatic pressure limit. The loading rate sensitivity of dynamic compressive strength decreases with the increase of hydrostatic pressure. Under the same loading rate, the failure strain is proportional to the hydrostatic pressure. The macro- and micro-fragmentation characteristics of coal show that the degree of coal fragmentation decreases gradually with the enhancement of hydrostatic pressure constraint. This research can provide a reference for the prevention and mitigation of typical dynamic disasters in deep coal mines.
- 1
Research on collaborative bearing performance of " coal pillar-filling body " under roof cuttingAbstract:
In order to analyze the influence of different " coal pillar-filling body " support on the stability of roadway surrounding rock under the action of roof cutting, taking the transportation roadway of 1226 fully mechanized mining face in a mine as the research background, the stress transfer process under the action of roof cutting and the variation law of vertical stress under different " coal pillar-filling body " support are studied by combining theoretical analysis with numerical simulation. The results show that under the condition of " coal pillar-filling body " support, the vertical stress of the solid coal side of the transport roadway is reduced by 9.5 % compared with that without roof cutting, and the vertical stress of the side of the coal pillar is reduced by 45 %. The horizontal deformation of the two sides of the transport roadway and the compression deformation of the roadside support are reduced by 21 % and 30.8 %, respectively. That is to say, the roof cutting and pressure relief technology can realize the double optimization of the stress and deformation of the surrounding rock of the transport roadway, which is conducive to the long-term stability of the surrounding rock of the transport roadway. The vertical stress of roadside support is the main controlling factor affecting the stability of roadway surrounding rock. The average reduction rate of vertical stress of roadside support increases linearly with the increase of filling strength, and the maximum is 5.8 %. The average reduction rate of vertical stress of roadside support increases first and then decreases with the increase of coal pillar width, and the maximum is 13.6 %. According to the influence law of the change of the cooperative bearing performance of " coal pillar-backfill body " on the vertical stress of roadside support, the functional equations between different coal pillar widths and the strength of backfill body and the vertical stress of roadside support are fitted. When the width of coal pillar is 7.5 m and the strength of backfill body is 6.5 MPa, the control effect on the stability of roadway surrounding rock is better.
- 1
Study on Quantitative Evaluation of Pressure Relief Effect and Stress Distribution Caused by Boreholes in Coal SeamAbstract:
Large-diameter boreholes are commonly used in pressure relief around coal roadways, but the quantitative evaluation of effects still needs to be improved. FLAC3D were carried out to explore the influence of borehole diameter, spacing and depth on pressure relief and these parameters were determined with orthogonal tests. Evaluation indicators of pressure relief caused by boreholes were proposed and the quantitative evaluation of pressure relief effected were studied using extreme difference analysis method. The stress redistribution after drilling in different strength coal have been discussed. The results have shown that: 1) The main influence parameter is diameter and with the increase of it, the pressure relief ratio K increase. The effect of spacing is second and the effect of depth is smallest; 2) Increasing the diameter is beneficial to increase the range of the pressure relief zone and reducing the spacing is conducive to forming a through pressure relief zone. Borehole depth has a great influence on the transfer distance of concentrated stress to the deep and the correlation is positive; 3) The penetration of the pressure relief zone can significantly reduce high stress and effectively avoid the stress concentration between boreholes. The study can provide reference for designing large-diameter boreholes in coal bodies with impact ground pressure.
- 1
YAO Xuan-cheng1, LIU Jia-ming1, GONG Hao2Abstract:
In order to study the formation mechanism of water inrush and sand bursting channel in overburden movement, laboratory test, field measurement, theoretical analysis, numerical simulation and other means are adopted in this paper. The caving form of thick overburden impingement, the propagation path of mining-induced fissure and the fracture form of thin bedrock are studied. Research results show that the thick alluvium caving form of symmetric caving arch and asymmetric caving arch alternating recurring forms, including the arch symmetry caving mining-induced fractures by the high thick alluvium has crack, and in the form of crack Ⅰ class to thin bedrock two-way began to extend down, cause a tensile fracture of the thin bedrock, working to ease pressure: The mining-induced fissure of asymmetric caving arch originates from the high thick alluvial layer and begins to expand unidirectional downward to the thin bedrock in the form of Ⅱ cracks, resulting in shear fracture of the thin bedrock and intense pressure at the working face. Based on the upper bound theorem, the theoretical equation of caving arch is obtained. The prediction results are consistent with the data obtained from similar simulation tests, which can be used to predict the evolution form of caving arch.
- 1
Study on the Propagation Characteristics of Blasting Vibration of Underground Engineering Surrounding Rock under Different Angle Cutting of Structural SurfaceAbstract:
In order to explore the influence of different structural face angles on blast vibration wave transmission in rock masses, the Separate Hopkinson Pressure Bar (SHPB) dynamic impact experiment was used to investigate it, and the reliability of the experimental results was analyzed in the context of actual engineering. Firstly, SHPB dynamic impact tests were carried out on rock samples with prefabricated structural face angles of 30°, 60° and 90°. Based on the experimental results, the calculation formula of the relationship between the maximum velocity reduction factor k and the structural face angle was proposed, and the calculation formula was verified by combining with the field monitoring data of Zhou Pan Gou tunnel. The results show that: the attenuation effect of blast vibration wave is most significant when the angle of the structural surface is 30°, and decreases with the increase of the angle of the structural surface; the correlation coefficient R2=0.982 of the formula proposed based on the experimental results for the relationship between the maximum vibration speed reduction coefficient k and the angle of the structural surface has a high fit; the formula is verified by the field monitoring data, and the calculation results are in good agreement with the actual results. The results of the calculation formula were verified by the field monitoring data, and the actual results were in high agreement with the actual results, indicating that the calculation formula has high reliability. This study can provide guidance and reference for the safe construction of underground engineering blasting.
- 1
Research on Hidden Danger Detection of Mineshaft Facilities Based on Deep Image Feature LearningAbstract:
Aiming at the problems of high cost and safety threat when manually detecting the facilities in the mineshaft, a hidden danger detection method of mineshaft facilities based on deep image feature learning (HDD-DIFL) is proposed by using the sampled video images of the mineshaft facilities. First, a dataset containing a large number of normal facility images and a small number of hidden danger images is built. Then a parallel neural network including feature extraction network and classification network is constructed as the training network, and a combine loss function is designed to train the network not only on the built dataset, but also on an external labeled image dataset. Finally, some representative normal deep features are selected as the feature templates by clustering strategy, and the hidden danger facility images are detected by template matching. The experimental results show that the proposed HDD-DIFL can effectively improve the representation capacity of the image features, and the detection accuracy exceeds 92% on the constructed derrick image dataset. It provides a new thinking for the hidden danger detection of the mineshaft by using the sampled facility videos.
- 1
Experimental Study on Improving Recovery Rate of Associated Gold and Silver in A Lead-Zinc Mine in QingHaiAbstract:
In order to improve the recovery rate of associated gold and silver in Xitieshan Lead-zinc Mine, the effects of grinding fineness, type and dosage of gold and silver collector, type and dosage of regulator on the recovery rate of associated gold and silver were investigated on the basis of process mineralogy. The test results show that the associated gold and silver mainly occur in lead minerals. In the test, the combined collector 25 # black powder + A11, T18 is used as the inhibitor of zinc minerals, and the closed-circuit process of one roughing, two cleaning and one scavenging is adopted. The lead concentrate grade is 67.55 %, the lead zinc content is 2.15 %, and the lead concentrate contains gold and silver of 5.01 g / t and 641.17 g / t, respectively. The lead recovery rate reaches 95.13 %, the gold recovery rate reaches 61.06 %, and the silver recovery rate reaches 81.96 %. The flotation index of associated gold and silver is better, which provides some reference for similar improvement of lead-zinc ore associated gold and silver index.
- 1
Experimental study on Beneficiation of a low grade molybdenum and lead ore in HenanAbstract:
The grades of molybdenum and lead, the main valuable elements of a molybdenum lead mine in Henan Province, are low, 0.083% and 0.32%, respectively. Molybdenum and lead minerals are closely related and have similar floatability. The efficient separation and separation of the two is the key to the effective development of resources. Through detailed process mineralogy research, develop reasonable and advanced beneficiation process, develop green and high-efficiency lead inhibitor system, and determine to use the combined process of "molybdenum lead mixed floatation - shaking table gravity separation - molybdenum lead separation" and the combination of "DP-1 + water glass + Sodium mercaptoacetate concentrate with Mo grade of 45.41%, Pb content of 0.65% and Mo recovery rate of 85.55% and comprehensive lead concentrate with Pb grade of 56.31% and Pb recovery rate of 85.58% are obtained, The high-efficiency separation of molybdenum and lead is realized and qualified molybdenum concentrate products are obtained, achieving good technical indicators.
- 1
Deformation Analysis and Stability Prediction of Surrounding Rock of the Tunnel Located in Water-rich Fault Fracture ZoneAbstract:
In order to ensure the construction safety of the tunnel located in water-rich fault fracture zone, on the basis of the large deformation analysis of surrounding rock in the ZK42+845~ZK43+050 section of the Yangzong tunnel on the left side of the Fuyi Expressway. The current situation and development trend of surrounding rock stability were evaluated by using grey-cusp-catastrophe theory and the SSA-ELM intelligent model. In addition, targeted support reinforcement measures were carried out in combination with the causes of the large deformation of surrounding rock of the tunnel, and the stability of the surrounding rock after treatment was comprehensively analyzed. The results show that the large deformation of surrounding rock in the Yangzong tunnel is closely related to the water-rich fault, micro-expansion of surrounding rock and high ground stress, and the development trend of collapse of the surrounding rock in this section can be seen from the sudden change characteristic value Δ<0 and the comprehensive analysis of SSA-ELM model deformation prediction. Radial grouting, over-grouting support, strengthening locking foot and footing channel, and adjusting the deformation amount effectively control the deformation trend of the surrounding rock in the tunnel through the water-rich fault section, and make the overall force of the surrounding rock more balanced. The comprehensive application of grey-cusp-catastrophe theory and SSA-ELM model can accurately and effectively evaluate the current situation and prediction of the surrounding rock stability, which has practical engineering value.
- 1
Determination and application of key technological parameters of coal gangue soil covering and ditchingAbstract:
The environmental problems caused by the large-scale accumulation and discharge of coal gangue have always been the focus and difficulty of the industry. Aiming at the characteristics of the development of gully on the surface of a coal mine and the large output of coal gangue, this paper proposes a treatment method of filling ditch with covering soil according to local conditions and enterprise conditions, and establishes a model of filling ditch with coal gangue layered with soil. This paper judges the flame retardant effect of coal gangue under different layer thickness ratios of "coal gangue + loess" by studying the change of temperature and seepage field inside the gangue discharge site. The research results show that: ① The content of heavy metals such as chromium, nickel, copper, and zinc in the coal gangue of this mine conforms to the agricultural soil standard and can be used as a material for filling trenches, ② With the increase of the overburden layer thickness, the temperature transfer speed and the air seepage speed in the coal gangue gradually decrease. Combined with the grey relational model, and considering the flame retardant effect and the moisture content of loess, the optimal covering soil thickness was determined to be 50 cm, ③ The technology of "300 cm coal gangue +50 cm loess" was determined and implemented. The field monitoring data showed that the temperature of coal gangue layer was close to the temperature of surface loess and the external temperature of surface, and the spontaneous combustion of coal gangue was well controlled. The research results can provide reference for the harmless disposal of gangue on the surface scale.
- 1
an Image Demisting Algorithm Based on Improved Weighted Guided Filtering for Underground Coal MineAbstract:
Aiming at the problems of image distortion, dark color and loss of details in the dust and fog image processing of underground coal mine based on the prior theory of dark channel, this paper proposes a dust removal and fog removal algorithm of underground coal mine image based on the prior theory of bright and dark channel. Firstly, the local atmospheric light is reconstructed by fusing the prior knowledge of light and dark channels; Secondly, analyse the filtering characteristics of bilateral filtering, establish an improved weighted guided filtering algorithm based on local pixel difference; Finally, the pixel difference between the dark channel atmospheric light and the original image is used to adaptively adjust the overall brightness of the image. Experimental results show that this algorithm can effectively remove the influence of dust and fog in the image. Compared with He algorithm based on guided filtering and Retinex-MSR algorithm, this algorithm has higher average gradient and standard deviation, and the restored image has higher definition, better visual effect and faster running speed, which meets the actual needs.
- 1
Study on Preparation and Properties of Alkali Activated Slag-Gold Tailings Based Foam ConcreteAbstract:
In response to the problems of large gold tailings stockpiles, disposal difficulties and low utilization rate of resource utilization, the synergistic utilization of mining-building materials-environmental resources is achieved by preparing alkali-excited slag foam concrete from gold tailings instead of traditional sand and gravel aggregates, and analyzing the effects of water-cement ratio, foam stabilizer admixture, foam admixture and water-glass modulus on slurry fluidity, dry density, thermal conductivity and compressive strength. The results showed that: the slurry flow increased and the dry density decreased during the process of increasing the water-cement ratio from 0.3 to 0.5, and the thermal conductivity and compressive strength increased and then decreased, and the thermal conductivity and compressive strength reached the maximum value when the water-cement ratio was 0.35. The effect of 0.1%~0.4% foam stabilizer dosing on the concrete performance was not significant, and with the increase of foam dosing, the concrete With the increase of foam admixture, the concrete structure forms a large number of connected pores, the porosity increases, and all the properties of concrete show a trend of continuous decrease. The water glass modulus is the key factor to improve the performance of concrete, when the water glass modulus is 1.6, the slurry flow is 149 mm, the dry density is 872 kg/m3, the thermal conductivity is 0.088 W/(m?K), and the compressive strengths at 3 d, 7 d, and 28 d are 10.16, 14.67, and 18.82 MPa.
- 1
Numerical simulation optimization research and engineering application on crushing stope spanAbstract:
In order to ensure the stability of the crushed ore body stope, reduce ore loss and dilution,To achieve safe and efficient mining,Taking the broken stope of an iron ore as the background,FLAC3D was used to analyze the stability of different stope widths and determine the reasonable stope structural parameters. By calculating and analyzing the variation characteristics of stress, displacement and plastic failure zone of roof and side wall of different stope widths in the mining process, the stability of stope under different parameters is obtained. The results show that when the stope width exceeds 14m, the stress and displacement of roof are larger, and the stability of stope becomes worse. With the increase of stope width, the variation range of lateral stress and displacement gradually decreases, which is beneficial to the stability of stope. When the width of stope is larger than 12m, shear failure occurs easily on both sides, and the stability of stope deteriorates. The optimization results are applied to engineering practice, and the stope width is suggested to be 10-12m, which can effectively ensure the production capacity and stability of stope. The research results have a certain reference significance for the optimization of stope structural parameters.
- 1
Damage law of mechanical properties of coal-rock mass with different strength under water-rock actionAbstract:
In the mine with rich water environment, the coal and rock mass as well as the water-resistant coal and rock pillar will be eroded by groundwater for a long time, which will cause the mechanical properties of coal and rock mass to change and be damaged under the action of water and rock, which will directly affect the stability of the mine and the safe production. Therefore, uniaxial compression tests of mudstone-coal-mudstone (N-M-N), sandstone-coal-sandstone (S-M-S), and limestone-coal-limestone (H-M-H) with different strength ratios of coal and rock were carried out before and after saturation to study the evolution law of mechanical properties and acoustic emission damage characteristics of coal-rock assemblage under water-rock interaction. Combined with RFPA2D numerical simulation, the influence of water-rock interaction on the failure form of composite body is analyzed. The results show that :(1) water-rock interaction has obvious deterioration effect on the compressive strength and elastic modulus of coal-rock mass; (2) The ae count and cumulative count of coal-rock assemblage decrease obviously due to water-rock interaction; (3) Water-rock interaction can significantly change the fracture propagation and fracture form of coal-rock mass, and the number of ae events is always accompanied by the occurrence and distribution of fractures. The research results can provide reference research value for the stability of coal-rock system and water-resistant coal pillar under the condition of abundant water.
- 1
Case study on slope stability analysis, monitoring and early warning based on FLAC3D-RARAbstract:
Taking the slope monitoring of an open-pit mine in the Democratic Republic of the Congo as an example, combined with FLAC3D numerical simulation and real aperture slope radar (RAR), the slope stability analysis and monitoring and early warning research are carried out, which realizes the accurate prediction of landslide area and landslide time, and strives for more than 3 hours of temporary landslide emergency disposal time for the site, effectively avoiding landslide losses;The radar monitoring data of RAR slope verify the accuracy of FLAC3D numerical simulation results in the aspects of displacement development and change characteristics of slope risk area, initial position of sliding failure and sliding area; At the same time, FLAC3D can timely find the risks outside the current landslide hidden danger area, make necessary supplements for radar monitoring, provide a basis for fully dealing with landslide hidden dangers, and improve the working level of open-pit slope. The research results can provide reference for the creep sliding failure early warning of similar slopes.
- 1
Influence and Mechanism of the Retention Time of Stored Materials on Sidewall Pressure and Ore-rock Fluidity in OrepassAbstract:
It is a common phenomenon during the process of mine production that the ore drawing at the bottom of the orepass is broken off remaining the stored material in the ore storage section of the orepass. Gravity compaction caused by the retention of stored materials in the orepass will change the porosity of the ore-rock bulk, thereby affecting the fluidity of the ore-rock, and adversely affecting the ore-rock release after the ore-drawing at the bottom of the orepass returning to normal. By constructing a platform for monitoring the pressure on the sidewall of the orepass, and using physical experiments, the influence of the retention time of the storage material on the sidewall pressure and the fluidity of the ore-rock under the action of gravity compaction is studied, and the mechanism of the influence is analyzed. The results show that: (1) When the height of the materials stored in the orepass is constant, with the increase of the retention time, the sidewall pressure of the orepass shows an obvious increasing trend; (2) The dynamic sidewall pressure of the orepass has the characteristic of increasing with the increase of the retention time. It is manifested that the dynamic sidewall pressure of the orepass is large and fluctuated at the beginning of the ore drawing at the bottom of the orepass, and after a period of ore drawing, the dynamic sidewall pressure of the orepass tends to be normal; (3) The retention time of the ore-rock bulk in the orepass has a significant effect on the fluidity of the ore-rock. With the increase of ore-rock retention time, in theinitial stage of ore drawing at the bottom of the orepass, the lower the ore drawing speed at the bottom of the orepass, the worse the fluidity of the ore-rock. And, with the continuous drawing out of the stored material, the fluidity of the ore-rock bulk tends to improve, and the ore-drawing speed becomes larger. Therefore, mining enterprises should shorten the residence time of ore in the orepass to increase the fluidity of the stored material and reduce the risk of the orepass blockage.
- 1
Study on the Optimization of Waste Cemented Filling Body Proportion and Reasonable Matching with Surrounding RockAbstract:
In order to study the mechanical properties of waste rock cemented fillings with different cement-sand ratios, this study carried out laboratory experiments on the ratio of waste rock cemented fillings, carried out nuclear magnetic resonance experiments on cylindrical waste rock cemented fillings cured for 14 days, and carried out uniaxial compression experiments on cubic waste rock cemented fillings cured for 14 days. The results show that the cement-sand ratio and the particle size ratio of waste rock have significant influence on the pore characteristics and mechanical properties of waste rock cemented backfill. When the cement-sand ratio is 1:2, the pore characteristics and mechanical properties of the backfill reach the optimal value. In addition, in the filling body with the same cement-sand ratio, the particle size ratio of waste rock is 3:2, which is the optimal ratio. Based on the above test results, the deformation energy of experimental fillings is further analyzed and calculated by the theory of fillings damage. Combined with the actual situation of surrounding rock excavation in No.1 mine of Bojitian, Changtian, Guizhou, it is the most reasonable to apply the ninth group (cement-sand ratio 1:2, waste rock particle size ratio 3:2) in this experiment to No.1 mine of Bojitian.
- 1
Study on mechanical properties of argillaceous siltstone undertriaxial compression based on fractal dimensionAbstract:
In order to study the deformation and failure characteristics of surrounding rock of argillaceous roadway under different stress environments, this paper selects typical argillaceous siltstone rock samples to carry out triaxial compression tests, and obtains the stress-strain curves of argillaceous siltstone under different principal stress loading rates and confining pressures. FLAC3D numerical simulation software was used to verify the triaxial compression test results, and it was found that increasing the principal stress loading rate and confining pressure of the testing machine can improve the compressive strength of rock specimens. At the same time, by collecting the debris of rock samples, the " particle size-number " fractal dimension method is used to analyze the failure law of rock samples. It is found that the greater the principal stress loading rate and confining pressure, the smaller the fractal dimension of debris, and the higher the degree of failure of the specimen. The above results show that the loading rate of principal stress and confining pressure can effectively slow down the crack propagation rate of rock specimen under triaxial compression, slow down the development of rock specimen damage, enhance its compressive strength, and reduce the fragmentation of specimen after failure.
- 1
Experimental study on rock failure law of repeated mining in very close coal seamsAbstract:
In view of the problem of erosive rock impact fracture during the repeated mining downward mining of the close coal seam group and the safety mining of the working face under the condition of regenerative broken roof, taking the 11221 and 11223 working faces of Paner Coal Mine as the research background, through the physical similarity simulation experiment, the law of erosive rock failure and fracture development of the extremely close coal seam group under repeated mining was studied. The results show that : 1 The average height of the erosive rock caving zone of the coal working face is 22 m, and the maximum development height of the fracture is 85 m, and the development height of the two zones is 24.2 times of the mining height. Affected by the joint mining of 3 coal and 1 coal face, the relative upward development of fracture zone increases by 15 m, the fully caving angle of rock mining is basically symmetrical, and the roof failure range increases. With the advance of the working face, the roof of the coal seam group experienced the evolution process of caving, fracture development, and gangue recompaction in the goaf. As the key layer, 14 m thick sandstone inhibits the upward development of fractures, and generates large separation below the end of mining. The caving form of overlying strata of coal No. 3 is approximately asymmetric ’ Π ’ type. After coal No. 1 is mined, compared with coal No. 3 working face, it shows the characteristics of ‘ two big and one small ’ : the height of ‘ two zones ’ is developed greatly, the height of caving zone increases by 46 %, and the height of fracture zone increases by 21 %. Large roof subsidence ; the roof caving step is small, the initial caving step and the periodic caving step are significantly reduced, and the weighting is relatively mild. The research results can provide theoretical basis for surrounding rock control of coal seam group mining.
- 1
Surrounding deformation and zoning control technology of soft rock roadwayAbstract:
The support of soft rock roadway under complex geological conditions is a technical problem for the stability control of surrounding rock, and the large roadway with a strong constraint of use conditions adds new challenges to it. Based on the field measurement and theory, the elastic damage mechanical model of the surrounding rock of the non-isobaric roadway is established, and the deformation characteristics and control methods of the surrounding rock of the west wing transport roadway in Ronghua mine are studied. The results show that the ratio of horizontal stress to initial horizontal stress is 4.3 ~ 8.5 after the fault is formed; Smaller internal friction angle, cohesion, and larger lateral pressure coefficient correspond to a larger plastic zone radius and a higher probability of butterfly-shaped plastic zone. The expansion speed of plastic zone radius can indirectly indicate whether butterfly leaves are formed; For soft rock that is easy to loosen, the support resistance should be maintained, and the surrounding rock properties should be improved at the initial stage of support; The horizontal fractures in front of the roadway are relatively developed, the overall deformation of the surrounding rock is small, and the displacement of the top and bottom and the two sides are within 150 and 40 mm respectively, which verifies the rationality of the zoning support strategy and support parameters.
- 1
Study on the Performance and Hydration Mechanism of Mineral Admixture Combined with Construction Waste Filling MaterialsAbstract:
In order to re In order to realize the synergistic treatment of urban construction waste and mine quarry area, we use construction waste as recycled aggregate and slag micronized powder and phosphogypsum as cementing materials, and adopt orthogonal tests to investigate the influence of slurry concentration, cement-sand ratio, mineral powder admixture and water-reducing agent admixture on the collapse degree, diffusivity and compressive strength of the paste-filled material. mechanism. The results of the study showed that the factors influencing the collapse and diffusivity of the paste-filled materials were in the order of significance of slurry concentration, water-reducer dose, mineral powder dose and sand ratio, and the factors influencing the compressive strength at 3 and 28 d were in the order of significance of slurry concentration and sand ratio. Mineral powder dosing water-reducing agent dosing. Under the synergistic excitation of alkali and phosphogypsum, the mineral powder glass phase mesh structure releases a large amount of active silicon and active aluminum, which re-polymerize with the calcium ions in the hydration system to form calcium alumina and C-S-H gel, and the hydration products are embedded on the surface of the construction waste particles to construct a dense structural whole.
- 1
Study on 3D Visualization Application of Rock Mass Quality Classification in Underground MinesAbstract:
Based on the RQD value of the exploration drilling hole in a mine, the 3D modeling visualization technology of Surpac software is applied, and the 3D model of rock mass quality classification and zoning in the mining area is constructed through the evaluation and calculation of 3D blocks. Statistical analysis of the spatial distribution of rock mass quality shows that the rock mass of the ore body accounts for 29.4% of grade I, 41.2% of grade II, 24.4% of grade III, and only 5% of grade IV and V rock mass , and above the middle section of -260m, mainly grades II and III, and below the middle section of -260m, mainly grades I and II. According to the analysis results, it is suggested that the mining area with rock mass below grade III should adopt the approach filling mining method. , I~II grade rock mass adopts the mining method of staged filling or staged open field followed by filling, and the underground chute or chamber layout avoids the rock mass below grade III according to the spatial distribution of rock mass quality, and the stope structure of deep ore body mining The parameters can be appropriately increased, the width is 15m~18m, the length is 45m~75m, and the stage height is 60m. The three-dimensional model of rock mass quality classification and partition provides important guidance for the production and construction of the mine.
- 1
Research on Automatic Positioning and Segmentation of Open Wagon Carriage in Mining Area Based on Voxel GridAbstract:
Iron and steel output is one of the important criteria to measure a country's industrial strength. With the deepening of the country's industrialization process, the demand for iron ore materials is also increasing. In order to meet the needs of the new era, the automation transformation of ore material workshop is the general trend. In the process of automatic transformation of the ore material workshop, multiple lidars are often used to sense the external environment information. In order to scan the entire workshop, the lidars are mostly installed on the top of the workshop. However, this installation method often causes the distance between the radar and the train to be too large compared to the distance between the gondola cars in the ore material workshop. Under this condition, the point cloud collected by the radar will be very messy, sparse and partially missing; As more and more mineral materials are accumulated in the carriage, the point cloud collected by the radar will also change continuously; And the trains in the workshop may have different models and sizes, and the trains will move forward after loading part of the carriages. These situations will bring difficulties to the automatic positioning and segmentation of the car. Based on this, this paper uses the idea of point cloud voxels for reference, and proposes an innovative point cloud automatic positioning and segmentation method for open car cars in mining area based on planar rectangular grid. Under the above unfavorable conditions, the relative error of this method can still be controlled within ± 1% through the actual data. However, in the actual project demand, it is only necessary to control the relative error within ± 8%. Therefore, it can be seen that the superior performance of the method in this case can provide a prerequisite for the automation transformation of the mining area.
- 1
Study on Brazilian test and crack initiation mode of granite under high temperature-water coolingAbstract:
In deep mining, ultra deep drilling, enhanced geothermal systems (EGS) and other projects, the thermal shock phenomenon of high temperature rock mass encountering cold water will cause damage to the rock mass, and the physical and mechanical properties of the thermally damaged rock mass have received extensive attention. In this study, the Brazilian test was carried out on the granite discs treated by high temperature-water cooling at 200 ℃~800 ℃, and the research shows that high temperature-water cooling caused the volume expansion of granite, the decrease of P-wave velocity, and the decrease of tensile strength. By monitoring the surface strain field and acoustic emissions during the loading process of the discs, it is found that the high temperature treatment will change the crack initiation mode of the granite discs. After the treatment at lower temperature (below 400 ℃), the crack initiation position is at the end of the disc, while the crack initiation position is at the center of the disc after higher temperature (600 ℃ and 800 ℃) treatment. Thermal shock leads to the increase of microcracks in granite, which makes the b-value during Brazilian tests increase with the increase of treatment temperature.
- 1
Dynamic Risk Assessment of Dam Failure of Expandable Cloud Tailings Reservoir Based on Objective Weight QuantificationAbstract:
In order to improve the objectivity of weight quantification and fully consider the dynamic influencing factors of tailings dam failure, so as to meet the needs of dynamic informatization development of mine safety evaluation, a dynamic risk assessment model of expandable cloud dam collapse based on structural entropy weight-numerical simulation is established. According to the dynamics and inherentness of the evaluation indicators, a dynamic evaluation index system for the risk of dam failure in tailings reservoirs is constructed; The comprehensive weights of evaluation indicators were calculated by using the structural entropy weight method and numerical simulation software to improve the objectivity of weight quantification; Introducing the theory of material element extension and the cloud model, the dynamic risk assessment model of tailings dam failure based on the extendable cloud model is constructed, and applied to the dynamic risk assessment of dam failure of a tailings reservoir in Hubei Province, the dynamic risk level is evaluated and the feasibility suggestions are proposed.
- 1
Research on coal and rock mechanics and damage characteristics based on true triaxial unloading experimentAbstract:
In order to deeply study the influence of excavation rate on coal and rock mechanics and damage characteristics in coal mining, a true triaxial unloading experiment of coal and rock under different unloading rates was carried out through the self-developed "Geoacoustic Process Simulation Test System". The results show that as the unloading rate increases from 0.05 MPa/s to 0.4 MPa/s, the maximum principal strain value, minimum principal strain value and volumetric strain value of coal rock under unloading failure decrease by 48.2 %, 42.5 % and 48.2 %, respectively. 113.1 %, and the intermediate principal strain value increased by 16.3 %; the larger the unloading rate, the more obvious the expansion of coal and rock; the failure form of coal and rock under the condition of low unloading rate is shear failure, while at high unloading rate Under the condition, it is tensile-shear composite failure; verified by the test data, the revised Drucker-Prager strength criterion is more suitable for the unloading failure of coal and rock; The larger the bell count, the higher the energy; the coal rock damage evolution equation established based on the accumulated ring count can describe the damage process in the unloading process of the coal rock well, The research results can provide reference for the stability prediction of actual engineering excavation.
- 1
Particle Flow Study of Uniaxial Acoustic Emission and Energy Dissipation Characteristics of RockAbstract:
Based on uniaxial acoustic emission test of gypsum rock and PFC2D particle flow simulation, the acoustic emission evolution characteristics of gypsum rock under uniaxial compression were analyzed. The process of microcrack initiation, convergence and failure was inverted from space, and the energy variation in the progressive failure process was analyzed. The results show that: the mesoscopic parameters of rock particle flow have different influences on the significance of macroscopic parameters. The relationship of macro-mesoscopic parameters can be quantified by orthogonal test and regression analysis. In the process of uniaxial compression, a large number of AE events occur in the post-peak stage, and the development process can be successively divided into non-destructive period, quiet period, growth period and sharp increase period. Before the sharp increase of AE events, there is a local quiet period, which can be used as a precursor criterion of rock failure. Tensile cracks appear first in the rock model, and internal cracks occur randomly in the pre-peak stage, with no obvious convergence. The macroscopic fracture surface is formed in the post-peak stage, and a large number of tensile cracks are concentrated near the fracture surface. In the pre-peak stage, the internal energy of rock is mainly stored in elastic energy, and the post-peak strain energy is released in large quantities, and the dissipative energy increases sharply. The energy dissipation ratio shows a "N" type change. The constitutive model based on acoustic emission test results is more suitable to describe the stress-strain relationship in discrete element uniaxial compression.
- 1
Spatiotemporal Differentiation of Land Use Degree in Reclaimed Coal Mining AreaAbstract:
Exploring the spatial heterogeneity of land use degree in reclaimed mining area is of great significance to realize the sustainable utilization of land resources. Taking the two-stage ( before and after reclamation ) Landsat images of Jiawang mining area in Xuzhou City as the data source, the spatial and temporal differentiation characteristics of land use degree in mining area before and after reclamation were discussed by using spatial sampling technology, land use degree index and land statistics method. Before and after reclamation, the land use degree of the mining area showed a positive global spatial autocorrelation relationship, which was 0.7076 and 0.6280, respectively. The high-high agglomeration areas of land use degree were mainly concentrated in the main urban area of Jiawang and the central town area in the southwest. The low-low agglomeration areas were mainly concentrated in the low hilly areas in the east and north of the main urban area of Jiawang. Due to the acceleration of urbanization and the construction of transport infrastructure, 20.87 per cent of the regional land use level has increased, mainly concentrated in the northern and central periphery of the study area ; 7.83 % of the regional land use degree decreased, mainly distributed in the southwest reclamation mining area and northeast of the study area, 71.30 % of the regional land use degree did not change, mainly distributed in the southern agricultural planting area of Jiawang District. The research results can provide basis for land use planning in mining area.
- 1
Improved Mask RCNN Algorithm for the Study of ore Segmentation and LocalizationAbstract:
Aiming at the low precision of ore segmentation under complex working conditions, an improved Mask RCNN instance segmentation algorithm was proposed. Because the Mask RCNN deconvolution operation to recover the ore using simple Mask, leading to the loss of the information, ore ore details loss for convolution, puts forward mixed attention module, the module will channel attention mechanism and the mechanism of spatial attention weighted fusion, can the channel level and space level to strengthen the characteristics of the ore information. Combined with the mixed attention module, the segmentation network structure of Mask RCNN was improved to reduce the loss of ore details in the convolution operation and improve the segmentation accuracy of the network for ore. The improved algorithm was compared with the original algorithm and other two commonly used algorithms. Experimental results show that the improved algorithm MIoU is about 87.1%, which is about 11.89% higher than the original algorithm, MPA value is about 94.61%, which is about 22.93% higher than the original algorithm. It has higher detection accuracy for ore identification and segmentation. The improved algorithm in this paper has a great application prospect for accurate identification and segmentation of ore under complex working conditions.
- 1
In-situ Improvement of V-Ti Magnetite Tailings and Planting Experiments Without Covering SoilAbstract:
According to the characteristics of shallow V-Ti magnetite tailings, the tailings were improved in situ by adding organic fertilizer, granulation agent, water-retaining agent and compound fertilizer, and the orthogonal experimental design of three factors and two levels was adopted, the physical and chemical properties and plant growth characteristics of artificial soil improved by tailings were studied through test analysis and planting experiments. The results showed that the quality of artificial soil improved in situ by V-Ti magnetite tailings was in line with the planting soil standard, and the plants had good survival rate and coverage, the suitable ratio of top artificial soil is 12% organic fertilizer, 0.4% granulation agent, 0.05% water-retaining agent and 0.6% compound fertilizer, the suitable ratio of bottom artificial soil is 4% organic fertilizer, 0.8% granulation agent, 0.2% water-retaining agent and 1.2% compound fertilizer .
- 1
Regression Prediction Model of Rock Triaxial Strength Based on Logarithmic FunctionAbstract:
The failure strength of rock has an important influence on the safety and economy of mining. In order to predict the failure strength of rock in triaxial compression under different confining pressure conditions, a logarithmic function-based method is established according to its nonlinear characteristics. Triaxial Intensity Regression Prediction Model. First, using the conventional triaxial test data of sandstone as the basic information, the mathematical expression of the prediction model is deduced by using the regression prediction method, and then the model is tested by four indicators, which preliminarily proves that the prediction results of the model are reasonable; The prediction model is compared with the widely used Hoek-Brown criterion and Mohr-Coulomb criterion. The results show that the average relative error MRE of the rock triaxial strength predicted by this model is only 5.01%, which is significantly lower than 12.72% and 9.10% of the other two criteria, with higher prediction accuracy; Finally, the applicability of the prediction model is verified by the triaxial test data of four different types of rocks in the existing literature. The results show that the model can predict the triaxial strength of these four kinds of rocks. The average relative error MRE is 6.93%~9.48%, all lower than 10%, and the applicability is good. The prediction model can provide reference for safe and economical structural design in mining engineering.
- 1
Research on optimization of blasting parameters for medium and deep holes in a mine under the effect of in-situ stressAbstract:
Reasonable blasting parameters are the guarantee of good blasting effect, and are the premise and foundation for achieving safe and efficient mining by bottomless column segmental crumbling method. To address the problem that the blasting parameters of the first row of deep holes in the first mining approach of the bottomless column segmental collapse method do not take into account the influence of ground stress, which causes uneven distribution of blasting block and brow line damage, this paper takes the middle three fan-shaped holes as the research object, and firstly analyzes the change of surrounding rock stress during the mining process of bottomless column segmental collapse method, and then uses ANSYS/LS-DYNA to simulate The results show that the effective blasting stress between the fan-shaped shell holes decreases as the horizontal tectonic stress increases, while the effective blasting stress near the free surface gradually increases. On the basis of this, the blasting parameters of the first mining approach/first row of shell holes were optimized, and the blasting of the first few rows of shell holes in the 23# approach in the middle section of mine 1580 was carried out in the field. The first few rows of shell holes were applied in the field, and the results showed that the crumbling ore body blast pile was concentrated, the crumbling ore block was more uniform, and the brow line damage was improved. The results of the study can provide guidance for the optimization of blasting parameters in deep holes in similar mines.
- 1
Technical Transformation of Paste Filling System of Main-western Orebody in Chambishi Copper MineAbstract:
In view of the unstable and uncontrollable underflow concentration of the common thickener in the paste filling system of the main west orebody in Chambishi Copper Mine, and even the cliff-like drop phenomenon, the causes of underflow concentration instability were analyzed and the corresponding measures were put forward by monitoring the data of the thickener on the spot. The two-system industrial concentration test was carried out, and the mathematical model of bottom flow concentration and mud pressure of deep cone thickener was obtained. The industrial test shows that the operation of two thickeners can maintain the stability of mud pressure and bottom flow concentration. Through the regulation measures of " inlet and outlet balance " and " high material level operation ", that is, when the discharge flow is 60 m3/ h and the mud pressure is 204-215 KPa, the bottom flow concentration fluctuates in the range of 67% -69.5% to ensure the quality of underground filling.
- 1
Numerical Simulation of Coupling Competitive Adsorption in Carbon Dioxide Displacement of Coalbed MethaneAbstract:
In order to reveal the change law of binary gas concentration in the process of carbon dioxide displacing coal bed methane, a multi-field coupling mathematical model of migration, displacement and desorption of methane and carbon dioxide in coal seam is established, based on Darcy seepage, Fick diffusion and extended Langmuir equation. The effects of carbon dioxide gas injection pressure and the arrangement of injection and extraction boreholes on improving coalbed methane recovery are numerically simulated. The results show that in the process of carbon dioxide displacing methane, a "methane enrichment area" will appear in the coal seam near the gas injection borehole, and with the increase of gas injection time, the "methane enrichment area" will gradually move to the exhaust borehole until the methane concentration distribution in the coal seam is stable, and the average methane concentration in the coal seam is 56.5% of the original gas concentration. The methane flow rate in the exhaust borehole first decreases, then increases rapidly to a peak, and then decreases slowly to a stable value. The conclusions can be drawn: the distance between injection and extraction boreholes has no effect on the methane flow after the methane concentration at the exhaust borehole is stable, but has an obvious effect on the peak value of methane flow and the time of peak value.
- 1
Ergonomic Analysis and Optimization Design of Trackless Manned Vehicle’ Cabins for MiningAbstract:
The human factors design is an important factor that affects the safety and comfort of trackless manned vehicle’ cabins for Mining. The complex working environment and the limitation of working space in mines pose a challenge to the design of the trackless manned vehicle’ cabins for Mining. In order to effectively improve the safety and comfort of trackless manned vehicle for Mining and improve the market competitiveness of enterprise products, JACK ergonomic virtual simulation software is used to analyze the trackless manned vehicle’ cabins for Mining that is widely used in the industry. Cockpit design elements that affect the occupant''s field of view, reach and comfort are extracted, practical research is carried out, and the layout and facilities of the cockpit are optimized. The optimized design scheme is experimentally verified, and the results show that the optimized design scheme effectively improves the driver''s field of view, reachable area and comfort, and improves the comfort of the passenger cockpit to a certain extent.
- 1
Optimization and Leaching Mechanism of Phosphogypsum Composite Cementitious MaterialsAbstract:
In order to realize the bulk utilization of phosphogypsum, mine filling materials were prepared with phosphogypsum, quicklime and slag micronized powder, and orthogonal tests were carried out to study the compressive strength, collapse, diffusivity, setting time and pH value of pore solution, and the hydration mechanism was elaborated by scanning electron microscopy, and the environmental compatibility was evaluated by toxic leaching test. The results showed that the compressive strength at 3 d, 7 d, 14 d and 28 d reached 1.57, 2.86, 4.03 and 7.49 MPa, the collapse degree was 26.8 cm and the diffusivity was 69.5 cm when phosphogypsum was mixed with 25%, quicklime was mixed with 6% and slag micro powder was mixed with 64%. The longer the age, the greater the pH of pore solution. The main hydration products of phosphogypsum gelling material are C-S-H gel and calcium alumina, and the hydration products closely wrap and jointly refine the capillary pores, blocking the dissolution of pollutants PO43- and F-, and the filler has good environmental stability.
- 1
An Equivalent “Bedding” Method of Jointed Rock Mass and its ApplicationAbstract:
It is very difficult to determine the rock mechanical parameters accurately for the discontinuity,which makes the rock mass heterogeneous and anisotropic.The anisotropy of rock mechanical parameters is hard to be considered using existing equivalent methods,an equivalent bedding method is proposed to study anisotropy of rock mass based on the theory of statistical dominant structural plane.At first,the software of Realistic Failure Process Analysis is used to study the size effect of mechanical parameters of rock mass on the basis of field measurement of discontinuity by ShapeMetrix 3D and laboratory experiment on rock mechanical properties.The anisotropy of the physical properties of the representative elementary volume was analyzed and the anisotropy mechanical parameters were determined.Furthermore,based on the dominant structural plane theory,the equivalent bedding is determined according to the principal direction of elasticity.Finally,the deformation and failure of surrounding rock of roadway with different equivalent bedding is analyzed by using the transverse isotropic elastic damage theory and finite element method.The results showed that the damage distribution area is obviously different with different joint angles,which is basically perpendicular to the equivalent bedding direction of rock mass;The direction of “bedding” also affects the maximum principal stress of roadway roof,therefore,only anisotropy of rock mass in roadway support design is considered can the safety of mine engineering be guaranteed.
- 1
Multi-factor Coupling Analysis of Flocculation Settlement Effect of Whole Tailings Based on RSM-BBDAbstract:
To address the problems of dewatering difficulties of dense tailing sand, slow settling rate and low bottom flow concentration, the mass fraction of tailing sand, flocculant unit consumption and flocculant solution concentration are used as independent variable factors, and the bottom flow concentration and settling rate are used as research indicators. The optimal flocculation and sedimentation parameters were determined according to the optimization of Numencial module. The results showed that the single-factor effects of bottom flow concentration and settling velocity were ranked in order of significance in terms of tailing sand mass fraction flocculant unit consumption flocculant solution concentration, and the interaction between tailing sand mass fraction and flocculant unit consumption was the most significant factor affecting the flocculation settling effect. The optimal combination of flocculant test parameters was 19.6% of tailing sand mass fraction, 26.05 g/t of flocculant unit consumption and 0.45% of flocculant solution concentration, which resulted in a bottom flow concentration of 63.98% and a settling velocity of 18.1 cm/min.
- 1
Effect of Polymer Emulsion on Properties of Cement-based Filling MaterialsAbstract:
In order to solve the problems of poor flowability and low strength of cementitious filling materials, we proposed a method to modify their properties with polymer emulsions, and comparatively studied the effects of three kinds of emulsions, namely, benzene propylene emulsion, pure propylene emulsion and VAE emulsion, on the flowability and mechanical properties of the filling slurry. The results showed that the 2% of benzene propylene emulsion and 6% of pure propylene emulsion promoted the flow of the slurry, and the VAE emulsion increased the viscosity of the slurry. VAE emulsions modified the compressive strength and flexural strength of the backfill better than styrene-acrylic emulsions and pure acrylic emulsions. When VAE emulsions were added 10%, the maximum compressive strength and flexural strength of the backfill reached 12.82 MPa, 16.55 MPa and 4.37 MPa, 5.63 MPa. When VAE emulsion content was 6%, the maximum compressive strength and flexural strength reached 16.25 MPa and 5.63 MPa at 28 d. Styrene-acrylic emulsion has the best modification effect on the tensile strength of the backfill. When the content of styrene-acrylic emulsion is 10%, the maximum tensile strength of the backfill reaches 1.77 MPa, 2.55 MPa and 2.91 MPa at 3, 7 and 28 days. With the age of hydration, the microstructure morphology of polymer emulsion modified filler developed from fine needle-like calcium alumina and flocculent C-S-H gel to short rods and agglomerates, and the hydration products and emulsion particles formed a tightly integrated organic-inorganic three-dimensional interpenetrating mesh structure, which filled the pores of the aggregate matrix and gave the filler good macroscopic and mechanical properties. The filler has good macroscopic mechanical properties.
- 1
Influence of Rock Structure Distribution on Electromagnetic Radiation Propagation under Stress WaveAbstract:
To further clarify the influence of rock mass structure on electromagnetic radiation propagation, Considering that the existence of joints is the cause of rock stratification, the Maxwell model is used to simulate the water-bearing joints.Combined with the piezoelectric equation, the analytical solution of the electric field changing with the joint parameters in the jointed rock is obtained. The influence of joints on the amplitude of electric field in single medium and composite medium is studied respectively also.The results show that the existence of water-bearing joints reduces the amplitude of electric field and attenuates the energy of electric field;the amplitude of electric field increases with the increase of viscosity coefficient and stiffness of joints;viscosity coefficient has greater influence on electric field amplitude than frequency in low frequency. For composite media, the variation trend of electric field with single parameter is clear by using fixed variable method. However, if the complexity of the actual combination of multiple factors is considered, the change of the electric field amplitude needs to be analyzed in detail according to the weight of the influencing factors.
- 1
Analysis on safety and stability of open-pit underground coordinated mining in Shizhuyuan Polymetallic MineAbstract:
In order to study the interaction of simultaneous open-pit and underground mining, taking Shizhuyuan Polymetallic Mine as the engineering background and according to the actual production situation of the mine, the surface model, the final boundary model of the open pit, the ore body model, the collapse area and the goaf model of the mine are constructed to truly reflect the deformation characteristics of mining and overburden rock as much as possible, The overall mining sequence of the mine is divided into six stages from top to bottom according to different mining heights and mining areas. Among them, the first to fifth stages are combined open-pit and underground mining, open-pit mining of ore bodies above 684m in the East and North, and mining of ore bodies above 612m in the West and south. At the same time, open stoping method of sub drilling stage is used to mine the ore bodies of 407m~610m in the East and 470m~536m in the north, and sublevel caving method is used to mine the ore bodies of 530m~610m in the West and 490m in the middle; At the end of the sixth stage, all underground mining will be converted to open-pit mining. Through the numerical model, the maximum displacement of surface and stope, the maximum tensile stress of stope roof and the location and magnitude of maximum compressive stress in each mining stage are obtained; The displacement and stress of underground stope, goaf roof and slope during open-pit mining are monitored and analyzed. The results show that during the open-pit and underground collaborative mining, there is no obvious stress concentration on the open-pit slope and platform formed in the open-pit mining area, and the displacement, tensile stress and shear stress values of the open-pit slope are small. The open-pit and underground mining of the mine have little impact on the final slope stability, and the displacement and stress concentration caused by mining will not pose a threat to the safety and stability of the open-pit slope.
- 1
Study on calculation method of critical temperature of coal spontaneous combustion based on numerical analysisAbstract:
The critical temperature of coal spontaneous combustion is generally 70~80 ℃. In order to take effective measures to control the temperature below the critical temperature in time, it is the key to accurately judge the temperature of coal in the process of coal spontaneous combustion. Coal will inevitably release CO gas in the process of natural oxidation. The early prediction of coal spontaneous combustion can be achieved by detecting CO gas. However, coal temperature is the key and reliable factor to determine the development degree of coal spontaneous combustion. Through experiments, the data of temperature and co volume fraction in the process of low-temperature oxidation of coal are obtained. Using the principle of numerical analysis, the relationship model between temperature and co volume fraction is established, and the inverse function of the model is solved, so as to establish the functional relationship between CO volume fraction and temperature in the process of coal spontaneous combustion, and realize the purpose of calculating the coal temperature in the process of coal spontaneous combustion by measuring co volume fraction. Applying this method to an engineering example, the prediction accuracy can meet the engineering requirements. This study provides a more reliable method for predicting the critical temperature of coal spontaneous combustion.
- 1
Research on Arrival Time Picking of Mine Signal Based on Improved Wavelet Threshold Denoising and Fractal Dimensionyangchengquan, 胡宾鑫, 李化坤, 耿文成, 郝鹏程, 纪旭波, 孙增荣, 朱峰, 张华, 李铁牛
Abstract:
It is key to accurately pick up the first-arrival of the microseismic waves to improve the accuracy of source location. The study proposes a high-precision detection algorithm for the arrival of microseismic first-arrival, which combines improved wavelet threshold denoising and fractal box dimension picking, based on the characteristics of multiscale analysis of wavelet variation and fractal box dimension to describe signal complexity and irregularity to overcome the shortcomings of the traditional first-arrival picking algorithm, which inaccurate in detection due to the influence of signal-to-noise ratio. The algorithm realizes the accurate detection of the arrival of the first arrivals by effectively reducing the noise of the microseismic signal by constructing an adjustable parameter threshold function to determine the threshold and select the adaptive threshold rule and calculating the box dimension curve. Experimental results show that the proposed algorithm is better than 3.6 ms detection accuracy under low SNR, which is significantly better than the traditional energy ratio method and AIC method.
- 1
Quantitative Scenario Analysis of Rare Earth Permanent Magnet Material Technological Development from the Perspective of Patent NetworkAbstract:
Rare earth permanent magnet materials are essential core competitive materials for the development of global modern industry. In order to identify the technical development focus in the field of rare earth permanent magnet materials in China and predict the future technical development trend, the utility model patents in this field from 1985 to 2020 included in the official website of the state Intellectual Property Office were studied based on complex network analysis and quantitative scenario analysis. The results show that the development of rare earth permanent magnet material patent technology in China focuses on the specific application of health care and physiotherapy, sewage treatment, medical devices, magnets and other industries in the embryonic stage, focuses on the motor industry and magnet preparation in the growing stage, and the patent technology is focusing on the cutting-edge technology of high-tech industries.The future development scenario of rare earth permanent magnet materials will focus on the coordinated development of the industry driven by the rapid development of a single technical field, mainly in the fields of motors, generators and electric load systems, followed by pumping devices, cooling devices, silencing devices, and finally in the fields of magnetic therapy, physiotherapy equipment, medical devices and so on; Supplemented by the coordinated development of multiple technical fields to drive the all-round development of the industry, there are mainly two types of patented technology fields, namely the fields of optical instruments, measuring instruments and the fields of grinding equipment, polishing machine tools.
- 1
Analysis of Meso-Deformation and Fracture Evolution Features of Coal based on CT Scanning under LoadingAbstract:
In order to analyze the mesoscopic failure features of high gassy coal, the staged CT scan under loading was performed on the 3# coal seam sample of Sihe coal mine. The region of interest (ROI) was selected and combined with the 3D digital image correlation method, the micron-scale 3D displacement and strain field of coal were obtained, and the features of fracture evolution were quantitatively analyzed. The following conclusions are: 1. minerals and primary fissures have different effects on the damage form of coal. Fissures affect the expansion form of new fissures, while minerals can easily lead to stress concentration, resulting in further damage.; 2. there are compressive strain and expansion strain in the coal under stress, and the internal stress state of coal is complex; 3. fracture density, fracture volume and fracture surface area can be used as indicators to characterize the degree of coal damage.
- 1
Study on Optimization of mining method and stope length in an iron mineAbstract:
a two-step sublevel drilling stage open stope and subsequent filling method has been used for mining in an iron mine since mining. Due to the existence of the hanging wall fracture zone of the ore body, the first step stope mining or the collapse of the exposed roof of the Stope at the end of the mining is caused, and the subsequent filling but the filling intensity is not known, which brings huge safety hazards to the second step ore body mining. Combining the technical and economic indicators, comparing the advantages and disadvantages of different schemes, it is finally decided to adopt the small segment filling mining method with reserved retaining wall to recover the two-step ore body. The production capacity of this method is 300t/d, the loss rate is 15%, and the dilution rate is 10-15%. According to the selected mining method, FLAC3D and rhino are combined to optimize the stope mining length. Finally, under the condition that the stope mining height and stope width are certain, According to the five selected schemes, the stress, displacement and plastic zone distribution are analyzed respectively. When the stoping length is 60m, it is safer. It can be used for reference by other mines in China.
- 1
Research on Failure Mechanics Mechanism and Control Technology of Fault Fracture Zone Passing through overlying Surrounding Rock of RoadwayAbstract:
In order to reveal the failure mechanics mechanism of the fault passing through the surrounding rock at the top of the roadway. Taking the structural fault roadway at the bottom of Pulang Copper Mine as the research background, based on the bending moment-strain energy theory, from the perspective of the mechanical behavior of the surrounding rock of the roadway affected by the fault, a mechanical model of the failure mechanism of the fault passing through the overlying surrounding rock of the roadway is established. It reveals the mechanical mechanism of the damage of surrounding rock in different parts of the roadway section due to the bending moment strain energy. Analyze the failure characteristics of the fault passing through the overlying surrounding rock of the roadway under the condition of different lateral pressure coefficients. The advantages and disadvantages of the mechanical environment of the surrounding rock of the roadway are: λ=1 is the best, λ<1 is the second, and λ>1 is the most unfavorable. The bending moment (strain energy) of surrounding rock at different parts of the roadway section is as follows: surrounding rock at the bottom of the roadway, surrounding rock at the arch of the roadway, surrounding rock in the middle of the straight wall of the roadway, the surrounding rock at the bottom of the roadway has the largest bending moment value, the largest accumulated strain energy, and the most The damage occurs first, and the focus is on strengthening the supporting parts. Comprehensive analysis of the damage of surrounding rock in different parts of the field roadway and field deformation and displacement monitoring data, combined with the failure mechanism of the surrounding rock of the roadway through the fault, proposes a new idea of regional coupling support technology, and realizes effective control of the damage of the surrounding rock of the roadway through the fault. The research results provide guidance for roadway surrounding rock control technology in abnormally complex geological environments such as fault fracture zones.
- 1
Design and Implementation of Mineral Processing Digital Computing System Based on Microservice ArchitectureAbstract:
Abstract: In order to solve the problem of process flow calculation in Beneficiation design and improve the speed and quality of beneficiation design, a calculation model of beneficiation process equipment is established through theoretical analysis and engineering practice experience. On this basis, a set of digital calculation system of beneficiation process based on micro service architecture is designed and developed. Based on the springbootalibaba framework, the system provides system management, beneficiation calculation, project query and other modules for department managers, designers and ordinary employees, breaking the barriers between traditional monomer beneficiation systems, ensuring high cohesion and low coupling from the architecture, making the system have good operability, maintainability and scalability. At present, the system has been used in China Enfei Engineering Technology Co., Ltd. and applied to the calculation of the quantity and quality process of mining and beneficiation works in a mine in Murong. The calculation results are the same as those of manual calculation and have higher accuracy, which shows that the system can calculate the beneficiation process flow efficiently and accurately.
- 1
Research on Intelligent Decision System of Driverless Vehicle Roadway IntersectionAbstract:
In order to make accurate decisions on the speed and safety of unmanned vehicles at the intersection of underground structure engineering, a collaborative decision-making system for unmanned vehicle safety at the intersection of underground structure engineering, especially mine roadway, is researched and developed. The system is mainly divided into three parts: information collection, decision control and intelligent collaboration. The design of the intelligent safety assistance system for unmanned vehicles at road intersections is mainly divided into: information collection, information extraction, decision control and function execution. Based on the position and speed data of the unmanned vehicle at the intersection of the roadway, the judgment mode of the movement characteristics of the intersection of the roadway is analyzed. The intelligent signal lights at roadway intersections can be flexibly converted between three conditions, which is convenient for artificial intelligence information to prompt vehicles, effectively reduce the occurrence of unmanned vehicle accidents at roadway intersections, and increase the traffic speed of intersections. It provides a reference for the intelligent decision-making of unmanned vehicles at the intersection of underground structure engineering roadway.
- 1
STUDY ON UPWARD HORIZONTAL CUT AND FILL MINING METHOD WITH MINING PREPARATION OUT OF VEINS IN STEEPLY DIPPING THIN ORE BODYAbstract:
In response to the problems of low mechanization of large equipment, poor continuity of the ore body and low production capacity in the mining process of the steeply dipping thin ore body, the deep succession project I-3 ore body of A'er hada Mining Company was used as the research object to investigate the conditions of the ore body and mining conditions, and the technical challenges of mining ore body were identified. Combined with the deep geological conditions and mining technology conditions, the traditional upward horizontal layered filling mining process was optimised, and an upward horizontal layered graded tailings filling mining method for sharply inclined thin ore bodies was proposed, forming a set of back mining, filling and lifting system for the efficient mining of steeply dipping thin ore bodies. The results of the field industrial tests show that the new method has significantly improved the mine output, production capacity and safety of mining operations, significantly reduced the loss rate and significantly improved the main technical and economic indicators, which is an important reference value for the same type of mines.
- 1
Safety Evaluation Method of Mine Ventilation System Based on Improved AHP-TOPSIS ModelAbstract:
It is of great practical significance to evaluate the safety of mine ventilation system in a systematic, quantitative and objective way to prevent accidents and ensure safe and efficient production in coal mines. Based on the analysis of the factors influencing the safety of mine ventilation system, a comprehensive evaluation index system of mine ventilation system safety is established by combining 33 secondary evaluation indexes from the composition of mine ventilation system, human-machine-environment and disaster prevention system; then the three-scale AHP method is used to calculate the weights of each index, and the Euclidean distance in the TOPSIS method is replaced by the gray correlation coefficient to construct an improved AHP-TOPSIS safety evaluation model of mine ventilation system; finally, the safety evaluation of mine ventilation system of Shengfu coal mine is carried out by applying the method. The results showed that the improved AHP-TOPSIS method introduced gray correlation coefficients to overcome the defects of Euclidean distance in the TOPSIS method, and the safety level of mine ventilation system is classified by calculating the relative proximity of gray correlation to make the evaluation results more consistent with the actual situation. The safety level of mine ventilation system in Shengfu Coal Mine belongs to Grade I (safety). The mine leakage rate (I11) is identified as a key factor affecting the safety of the mine ventilation system by step-by-step reverse analysis, providing a basis for optimizing and improving the safety of the mine ventilation system.
- 1
Experimental study on improving zinc flotation index of a lead-zinc sulfide mine in Inner MongoliaAbstract:
A lead-zinc mine in Inner Mongolia has complex ore properties. The raw ore has low lead-zinc grade and high sulfur content. In order to better recycle the lead-zinc mine resources, a detailed small-scale experimental study was carried out. The new process uses copper sulfate as zinc sulfide mineral activator, butyl xanthate as collector, and 2# oil as flotation foaming agent for lead flotation tailings. Zinc is obtained by second roughing and second sweeping flotation. Sulfur mixed coarse concentrate, after regrinding the mixed coarse concentrate, the product after regrind uses lime + sodium humate to strengthen the suppression of pyrrhotite-containing pyrite minerals, and adds a small amount of copper sulfate and butyl xanthate to activate the capture The zinc sphalerite with poor floatability is collected, and zinc concentrate and sulfur concentrate are obtained through primary separation and roughing, secondary sweeping, and tertiary beneficiation. In the closed-circuit test, under the condition that the raw ore contains 1.19% lead and 2.36% zinc, a lead concentrate containing 45.80% lead, 2.54% zinc, and a lead recovery rate of 71.32% can be obtained; a lead concentrate containing 0.86% lead, 44.38% zinc, and zinc For the zinc concentrate with a recovery rate of 85.95%, the new process has achieved good flotation indicators. The recovery rates of lead and zinc have been increased by 0.34 and 7.29 percentage points respectively compared with the on-site process, which provides guidance for the actual production of the lead-zinc ore.
- 1
Research on Dust Suppression Performance of Air Curtain During Grab UnloadingAbstract:
In order to restrain the diffusion of dust during the unloading process, an air curtain dust isolation system was designed to limit the diffusion of pollutants and effectively block air flow, so that the average mass fraction of pollutants out of the air curtain plane was reduced by 70.02%. Firstly, the grab unloading model is constructed by CFD-DEM coupling method, and the diffusion law of gas-solid two-phase flow field is studied, and the velocity distribution and trajectory of air flow field and particle flow field, as well as the maximum velocity of air flow field in each plane above the hopper are obtained. Using the 3D model of air curtain jet, the air curtain parameters are set based on the maximum air flow field velocity to simulate the air curtain barrier performance under different air curtain jet mode, jet width, air curtain jet velocity and induced wind velocity. The results show that choosing appropriate jet width and jet velocity can obviously reduce the dust diffusion; under different jet modes, the order of influence is blow and suction>unilateral blowing>bilateral blowing; under a certain range of induced wind velocity, the air curtain has obvious blocking effect.
- 1
Study on the Characteristics of Surface Subsidence in Multi-face Mining in Medium-deep Coal SeamAbstract:
The characteristics of surface subsidence in successive mining of multiple working faces in middle and deep coal seams are studied, and the characteristics of overlying rock failure, stress change and surface movement in 112201 working face of Xiaobaodang No. 1 well and adjacent working faces on both sides are simulated by FLAC3D finite element software. Research shows that: In single face mining, the plastic failure of overlying rock shows the "concave" type of low in the middle and high on both sides, and the maximum failure height of overlying rock reaches 165m, the mining of the adjacent southwest face increases the secondary failure height of the overlying rock in the old goaf by 11%, and the adjacent northeast face increases the tertiary failure height of the overlying rock in the old goaf by 3.8%; With the mining of adjacent face, the stress change of overburden in the first mining face goes through a complex process of "equilibrium-activation-initial balance-secondary activation-rebalance-tertiary activation-final balance"; The scope of the surface movement basin formed by the mining of a single working face is greatly affected by the mining of the adjacent working face, and the subsidence center is biased to both sides, while the subsidence center of the adjacent working face is inclined to one side of the old goaf of the first mining face; The measured data of rock movement show that the surface subsidence curve of single working face is "V" type, the pushing and mining of adjacent working face increases the maximum surface subsidence by 5%, and the surface subsidence curve is finally "W" type.
- 1
Instability mechanism and control countermeasures of thick argillaceous layered roof in mining roadwayAbstract:
In view of the easy deformation and difficult support characteristics of large thickness argillaceous layered roof with low strength, weak interlayer effect, small layered thickness and large cumulative thickness, taking 33053 stoping coal roadway of Zhaozhuang coal mine as the engineering background, the engineering geological environment, support mode and roof instability characteristics of coal roadway are obtained through investigation, the Winkler foundation model of roof rock beam of coal roadway is constructed and the deflection expression is solved, the flexural subsidence characteristics of roof rock beam of coal roadway and its key influencing factors are analyzed, and the instability mechanism of large thickness argillaceous layered roof of coal roadway is revealed. Based on the combination and compression effect of bolt (cable), a roof beam arch coupling bearing structure with continuous structure and prestress is proposed, and the formation mechanism of the combined compression bearing beam structure in shallow strata and the compression bearing arch structure in deep strata and the coupling mechanism between them are expounded. The field engineering application results show that the large thickness argillaceous layered roof coal roadway with different lengths of prestressed anchor cables and bolt support technology can significantly reduce the deformation of surrounding rock and the breaking rate of bolt (cable) in the whole service cycle, effectively ensuring the stability of surrounding rock.
- 1
Identification of Mineral Image under Microscope Based on Deep LearningAbstract:
The microscopic identification of minerals plays a pivotal role in many fields, but the traditional identification methods are of high requirement for professional knowledge with large workload. It is of significant importance to realize the intelligent identification of microscopic mineral image features with the help of deep learning and image processing techniques. In this experiment the images of pyroxene, quartz, hornblende, olivine and plagioclase were collected and investigated. On the basis of augment of the finite data set adopting OpenCV to effectively expand the scale of data and reduce the sample imbalance, the model was optimized based on the ResNet-50 network and trained using the strategy of transfer learning. The experimental results indicate that the intelligent identification and analysis of microscopic mineral image features can be successfully realized by the optimized network model, whose identification accuracy is greatly improved to reach up to 98.48% in the model test; Moreover, the training efficiency of the network was greatly improved with the faster convergence speed and the lower training time.
- 1
Research and Practice on Deformation Measurement Accuracy of High and Steep Slope Based on Measuring RobotAbstract:
In view of the landslide disaster of a high and steep slope in a tungsten mine, the automatic total station instrument is used for on-line monitoring and warning of the surface displacement, an automatic total station deformation monitoring system based on long distance polar coordinate difference method is established. The theoretical formula of measuring accuracy of 3D deformation of deformation monitoring point is derived. When the slope distance is 1200m ~ 1900m and the vertical angle is 5°~25°，the measuring accuracy of elevation deformation is between 2.2mm ~ 6mm and plane deformation is between 2mm~5mm when the measuring accuracy of angle is 0.5′and distance is 0.6mm+1PPM. The measuring accuracy reaches the millimeter level, which meets the requirements of the code. Through nearly three months actual survey data examination, because of the topographic condition restriction, the actual arrangement control datum point has the flaw, the atmospheric environment influence, the measuring accuracy of the height deformation and the plane deformation of the deformation monitoring points are both within ±10mm, and the measuring accuracy of the plane deformation is higher than that of the height deformation, in the range of measuring precision, the cumulative deformation of every deformation monitoring point is in random and stable state, and the high and steep slope around the collapse pit is in stable state.
- 1
Floor heave mechanism and control technology of roadway under superimposed dynamic pressureAbstract:
The control of roadway surrounding rock under dynamic pressure superposition effect is of great significance for safe and efficient mining. Taking the floor heave roadway under the influence of typical secondary mining in Yuwu coal industry company as the engineering background, the mechanism and control measures of floor heave in the roadway are studied by means of theoretical analysis, numerical calculation, and field measurement. The main conclusions are as follows: Under the condition of secondary mining, the low horizontal stress, vertical stress, and high shear stress transfer to the side of small coal pillars, the depth of floor damage is 1.9 times that of primary mining, and the extreme value of floor damage transfers to the deep, which is 3.0 times that of primary mining. When the floor stiffness is less than 30 MN·m2, the floor heave value strongly correlates with the floor stiffness. The floor heave deformation speed increases sharply when the roadway width exceeds 4 m. Based on numerical calculation and field measurement, it is revealed that the floor heave of the s2106 gas drainage roadway is an extrusion flow type under high stress. A support system with the core of "two reinforcement + floor reinforcement" is proposed, which verifies the water expansion bolt's feasibility and realizes the roadway's stability under the influence of superimposed dynamic pressure.
- 1
Study on the Dynamic Mechanical Properties of Ice-saturated Flawed Sandstone under Drop Weight ImpactAbstract:
In order to study the dynamic mechanical properties of ice-saturated fractured sandstone(IFS), the influence of fracture dip angle(FDA) on dynamic mechanical properties and crack propagation process of IFS was revealed by drop weight impact test and PFC numerical simulation. The test results show that the strain time-history curves of IFS with different FDAs are consistent, FDA only affects the magnitude of peak strain. When the flaw is horizontal, the peak strain is minimum, additionally, with the increase of FDA, the peak strain increases by more than 50 %. The specimen is mainly tensile failure. Moreover, numerical results show that cyclic impacts affect the shape and slope of stress-strain curve of IFS. Furthermore, variations of initiation stress, initiation strain and number of microcracks with FDAs are basically consistent, that increasing first and then decreasing with the increase of FDA. However, the peak stresses increase linearly with the increase of FDA.
- 1
Safe and efficient mining design and stability analysis of seabed gold mine with broken surrounding rockAbstract:
Due to the special and complex ore rock occurrence conditions in the upper and lower walls of Sanshandao Gold Mine, some stopes and roadways have collapsed and pumped out. Therefore, the mine chose to comprehensively treat the goaf before mining. In order to minimize the mining impact of secondary mining and ensure that the subsequent mining can be carried out safely and efficiently, the basic principles of secondary mining are first established, and then through the analysis of the governance of each level of the mine and the existing ore volume, the ore block division is carried out, and the first mining area is determined in combination with the existing system engineering of the mine and the past mining conditions. Finally, the three-dimensional fine model of the orebody, fault, fracture zone and roadway engineering in the first mining area is built, the upward drift filling mining method design of the reserved pillar is carried out according to the on-site engineering geology and mining technical conditions, and the stability analysis of secondary mining is studied based on numerical simulation. The research shows that the upward drift filling mining method of the reserved pillar can reduce the mining impact of the secondary mining and realize the safe and efficient mining of the seabed mine. The economic and technical indicators are as follows: the loss rate is 14%, and the dilution rate is 4%; The production capacity of the stope is 110t / d.
- 1
Creep Model of Anthracite and FLAC3D Secondary DevelopmentAbstract:
Fractional Abelian dampers can be used to characterize the accelerated creep stage of the creep model. In order to describe the acceleration stage of anthracite creep model more accurately, this paper introduces "gyro" element and displacement step function on the basis of previous work. The triaxial creep test of anthracite was completed by design, and the creep stage of anthracite was subdivided into five stages: instantaneous deformation, false acceleration, deceleration, constant velocity and accelerated creep. The model of each stage is combined with appropriate components to form the combined fractional creep model. The one-dimensional constitutive equation of the model is extended in three dimensions, and the model equation is differentiated by finite difference. Based on the Burgers constitutive model of FLAC3D, the combined fractional creep model (NEGS) is developed. The numerical simulation results show that the combined fractional creep model (NEGS) can better characterize the variation characteristics of anthracite at different creep stages.
- 1
Study on Creep Characteristics of Coal and Rock With Pressure Relief HoleAbstract:
In order to study the creep characteristics of coal with pressure relief holes, the creep tests of intact coal and coal with pressure relief holes under uniaxial compression were carried out under different stress levels. The test results show that the creep of coal and rock undergoes the evolution stages of instantaneous elastic deformation, deceleration creep, isokinetic creep and accelerated creep under the same stress level; The instantaneous creep and creep of coal and rock with pressure relief holes are larger than those of intact samples; The numerical simulation results based on FLAC3D are very similar to the actual test results, which shows that the Burgers model can better reflect the physical and mechanical properties of coal and rock creep. The conclusion has a good theoretical significance for the long-term strength analysis of coal and rock mass with pressure relief holes and rockburst.
- 1
Study on Classification Efficiency of Raymond Machine based on Gas-solid Two-phase Flow CouplingAbstract:
In order to investigate the influence of the rotor cage parameters of the classifier on the particles collection efficiency in Raymond mill, the gas-solid two-phase flow coupling simulation of the Raymond mill is carried out based on the discrete DPM model of FLUENT software, and the response surface experiment is designed by using Design-Expert10, the rotating speed of rotor cage, the number of blades and the angle of blade installation were taken as variables, and the particle collection efficiency was taken as the research object.The simulation results show that increasing the rotor speed and the number of blades is beneficial to improve the production efficiency. The results show that the particle trajectory is mainly affected by the wind field, and the local eddy current can change the particle trajectory, so the optimal structure design can reduce the local eddy current as much as possible, to ensure that the particles can be smoothly graded movement.Combined with the wind field trend analysis, it is concluded that the small radial velocity of particles in the classification area is conducive to the smooth entry of particles from the blade clearance into the cage for classification; higher tangential velocity is favorable for collecting smaller particles.This study provides a method to improve the efficiency of particle collection and optimize the structure of Raymond mill.
- 1
Numerical Simulation Study on Progressive Instability of Rock Slope under Cyclic VibrationAbstract:
In order to deeply study the progressive failure of the rock slope under cyclic vibration, the corresponding numerical model is established by using 3DEC numerical simulation, and the rationality of the model is verified based on the results of shaking table test. Then, the influences of rock layer parameters, e.g. dip angle, cohesion and friction angle on the progressive failure law of rock slope under cyclic vibration are analyzed from the following three aspects, e.g. dynamic response, stability coefficient and failure mode. The results show that with the increase of the number of cyclic vibrations, the stability of the slope generally decreases, but when the damage of the slope reaches a certain level, the stability will decrease rapidly and the damage rate will continue to increase, this eventually leads to slope instability. The influence of the rock layer parameter on the progressive failure of the slope from large to small is friction angle, cohesion, dip angle. The slope stability increases with decreasing the rock layer cohesion and friction angle, or increasing the rock layer dip angle respectively. The acceleration responses of each slope model show "elevation effect" and " aspect effect the dynamic response increases with decreasing the rock layer cohesion and friction angle, or increasing the rock layer dip angle respectively. The failure modes of the slope are mostly "tension-shear failure", and a few are "buckling failure
- 1
Study on the internationalization level and quality improvement of China’s green mine construction based on standards comparisonAbstract:
Green mine construction, internationally known as sustainable mining or responsible mining, has become a broad consensus and fundamental requirement for mining sustainable development. The comparative study of the differences between domestic and foreign standards is not only of great significance for a deep understanding of the internationalization level of China's green mine construction, but also can provide experience for further improving the quality of standards and practices. Through the comparative analysis of the 38 performance objectives of the ICMM sustainable mining principle and the six major aspects of the green mine construction specification of China's non-ferrous metal industry, it is found that some contents of China's standard are in good contrast with ICMM, and the element setting is relatively consistent with the ESG concept, which not only covers the environmental problems of mining, but also puts forward requirements for enterprises to bear social responsibility and key issues of corporate governance. Based on analysis of the specific requirements of different government sectors, it is considered that the China’s green mine construction practice has certain international progressiveness. Based on the reasonable reference of ICMM mining principles and the objective analysis of domestic situations and problems, it is proposed that the current standards should integrate the requirements in the environmental fields such as climate change, energy conservation and emission reduction, resource conservation and utilization, water management, environmental governance, tailings disposal, social issues such as workers' rights, health and safety, as well as the prevention of corruption, information disclosure, risk management and other governance contents, so as to build a standardization system framework covering the whole life cycle of mining, and different size mining enterprises.
- 1
Study on Pillar Width and Backfill Strength of Subsequent Filling Stope Based on Principal Component AnalysisAbstract:
The open stoping is made between flat-back cut and fill mining stope Pillar is an important structure inside underground mining space in open stope with backfill. Its size will affect the safety of mine production, resource recovery and enterprise economic benefits. The characters of pillar stress, deformation and plastic zone are often analyzed to evaluate the stability by numerical simulation for such problem, but there is no comprehensive evaluation method to integrate the above data. Therefore, Daniu Iron Mine was set in the research background. The comprehensive evaluation index of pillar stability was established according to the maximum compressive stress, shear stress, displacement and plastic zone proportion of pillar under different pillar width and backfill strength obtained by numerical simulation based on Principal Component analysis (PCA). Finally, pillar width and backfill strength were determined with the goal of pillar stability and optimal economic benefit. The results show that: (1) The result can be obtained according to the fusion of compressive stress, shear stress, deformation and plastic zone based on PCA by numerical simulation. When the uniaxial compressive strength of backfill is 1.5 MPa, the pillar width b decreases from 10 m to 9 m to ensure the stability of pillar. (2) Similarly, when pillar width b =10 m, the uniaxial compressive strength of backfill can be reduced to 0.5 MPa; (3) When b =10 m, σ=0.5 MPa, the comprehensive evaluation of pillar stability and mine benefit is the best. The research methods and results can be used to be referred for similar projects.
- 1
Statistical Analysis of Coal Mine Safety Accidents in China from 2012 to 2021Abstract:
Based on the data of coal mine accidents in China from 2012 to 2021 published by Coal Mine Safety Network, the statistics and comprehensive analysis are carried out from four aspects of grade, type, time and region to reveal the law of coal mine accidents in China and provide reference for the safe production of coal mines. The analysis results show that the coal mine safety situation in China has continued to develop well in the past ten years, and the prevention and control of large and above accidents have achieved remarkable results, but the general accidents are frequent and the number shows a fluctuating upward trend, so the number of coal mine accidents shows a wavy upward trend. The number of deaths caused by coal mine accidents showed a wavy downward trend. The number of accidents and deaths showed seasonal and temporal variations. There are also obvious regional differences in coal mine safety production in various provinces. Most of the general accidents are roof, electromechanical, transportation and other accidents ; gas accidents accounted for nearly half of the major and major accidents, followed by roof and water disasters ; all major accidents are gas accidents. Gas and roof accidents are the focus of coal mine safety control. The research results can provide certain reference for the prevention of coal mine accidents.
- 1
Evolution law of surrounding rock stress and permeability in very close coal seam miningAbstract:
In order to explore the evolution law of surrounding rock stress and coal permeability in the mining process of very close coal seams in the working face, taking the coal sample of No. 15 mining area of Xuyong No. 1 coal mine as the research object, the coal permeability measurement test is carried out, and the distribution law of effective stress of coal is studied by using FLAC3D numerical simulation software, the relationship between permeability and surrounding rock stress is analyzed, and the evolution law of coal permeability in the working face is summarized, The gas drilling layout parameters of high-level drilling yard are optimized. The results show that: (1) the permeability of coal is related to the stress state of surrounding rock. The higher the stress level of surrounding rock, the lower the permeability of coal; (2) The permeability of coal body increases gradually with the decrease of effective stress, which is a power function relationship; (3) After optimizing the layout parameters of gas boreholes in the high-level drilling yard, the best drainage stage is the drilling distance of 40 m. at this time, the effective drilling rate is 100%, the average concentration of a single hole reaches 80%, and the average flow reaches 0.58 m3/min, which can provide a reference basis for on-site gas drainage work.
- 1
Study on Structural Parameters of Mining Field with Sublevel Caving Method without Sill Pillar for Steeply Inclined Medium-thick OrebodyAbstract:
In view of the difficulty in determining the stope structural parameters in the mining of steeply inclined medium-thick orebody by sublevel caving method without sill pillar, based on the Bergmark-Roos equation ore drawing theory, the spatial arrangement characteristics of ore drawing ellipsoid in the stope were analyzed, and the calculation methods of theoretical loss rate and dilution rate were deduced. The optimization program of stope structure parameters of sublevel caving method without sill pillar for steeply inclined medium-thick ore body is developed based on Python language. After inputting the dip angle, thickness of ore body and flow parameters of ore rock bulk through program, the stope structure parameters of steeply inclined medium-thick ore body can be automatically calculated by the program, which changes the determination method of stope structure parameters of traditional sublevel caving method without sill pillar, and effectively solves the problem of determining stope structure parameters. Combined with the actual situation of an iron mine, the stope structure parameters were calculated by the optimization program, and the PFC2D numerical simulation drawing test was carried out according to the calculation results. The study shows that the ore drawing indexes calculated by PFC2D numerical simulation and optimization program are generally in good agreement. The average error of ore loss rate is 1.82%, and the average error of dilution rate is 1.17%. In addition, the mining parameters calculated by the optimization program are lower than 15%, and the ore drawing effect is better, which can provide guidance for the design of structural parameters of stope without pillar sublevel caving method.
- 1
Study on Parameters of Deep Hole Blasting in Hard Rock of Inclined Penetrating Fault in Hetaoyu Coal MineAbstract:
The oblique penetrating fault on the side of the encounter roadway in 2804 working face of Hetaoyu Coal Mine has a large range of influence, and the coal machine is inefficient in cutting full-section hard rock, which hinders the normal production of the mine. In order to ensure the smooth passage of the working face during the initial mining, the sandy fault hard rock should be pre-split by blasting in advance. Based on the engineering background, the numerical simulation software LS_DYNA is used to establish the blasting calculation model with different pore diameter and different spacing, the influence of different pore size on the law of force wave propagation is analyzed, and the crack development shape under different hole spacing is studied. The results show that the stress peak value increases with the increase of pore diameter in the range of 70~100mm, and the time when the stress peak appears is lagged correspondingly. When the pore diameter is 100mm, the increase of stress peak value is smaller than that of 90mm, and the influence of pore diameter change on stress peak value is weakened. It is determined that the best deep hole blasting hole diameter is 90mm. Through the analysis of the crack penetration degree between the blast holes and the stress value of the central measuring point unit, when the hole spacing increases from 1.2m to 1.3m, the stress decreases by 2.2%. It is appropriate to determine the hole spacing to 1.2m. By setting up independent blasting roadway and adopting the grouping blasting technology of "Wuhua Eye" with large charge, the problem of advance pre-splitting of fault hard rock is well solved.
- 1
Numerical Simulation of Water Inrush Induced by the Unloading Effect of Tunnel ExcavationLI Yangyang1,2,ZHU Huicong1,2,ZHANG Shichuan1,2,YANG Weihong3Abstract:
Water inrush from fault activation induced by unloading of engineering rock mass during tunnel excavation is one of the important research contents in the field of geotechnical engineering. Taking a subway station in Qingdao as the geological background, with the help of COMSOL multiphysics numerical simulation software, this paper establishes a solid fluid coupling model for tunnel excavation with different dip angles, analyzes the surrounding rock stress field and seepage field in the process of water inrush caused by fault activation induced by tunnel excavation unloading, obtains the mutual feed linkage mechanism between different dip angles of faults and excavation unloading effect, and defines the key water inrush points and water inrush conditions. The results show that the 55 ° dip fault is the first to activate, and the fault has the worst effect on stress absorption and barrier; As the dip angle of the fault increases, the sensitivity of the fault to the excavation unloading effect decreases. The seepage field is more sensitive to the change of fault dip angle. The larger the dip angle is, the stronger the water conductivity of fault collection is, and the faster the migration change of overburden seepage field is. The research results can provide theoretical reference value for the prevention and control of fault activation water inrush accidents in the process of underground mining of subway, tunnel and coal.
- 1
Study on Mechanical Properties of Cemented Backfill with Different Forms in a MineAbstract:
In order to further study the influence of shape effect on the mechanical properties of filling body, taking the fine-grained tailings of a mine as the research object, different shapes of filling body specimens are poured. Through the uniaxial compression test, the influence law of different shapes on the mechanical properties of filling body is obtained, and the strength correction coefficient under the influence of shape effect of filling body is established. The results show that: (1) Under uniaxial compression, the specimens with different shapes of backfill have similar stress-strain curves, which can be roughly divided into four stages: initial compaction, linear elastic failure, plastic failure and post peak fracture instability. (2) The uniaxial compressive strength of cemented backfill with different forms of fine tailings is linear, and the strength correction coefficient is 0.65~0.81. The research results have important reference significance for the accuracy of fine-grained tailings filling test in the future.
- 1
Study on the Preferred Section Shape and Support Method of Layered Rock Mass RoadwayAbstract:
When constructing a roadway project in a layered rock mass, the dip angle of the rock largely determines the deformation and failure characteristics of the roadway, and the selection of a reasonable roadway section shape and support method is essential to maintain the stability of the roadway. In this paper, the failure mode of layered rock mass roadway under different dip angle is systematically studied by numerical simulation method, and the preferred principle of layered rock mass roadway section shape is determined by combining with pressure balance arch theory, and then the corresponding support method is proposed. The research results show that in the process of gradual change of dip angle from horizontal to steep, the failure mode of the roadway roof also evolves from symmetrical arch caving to asymmetrical wedge-shaped caving, and even overall slip failure. Based on the self-stabilizing characteristics of the roadway under pressure balance arch, the straight-wall arch section is recommended for the layered rock mass roadway with arch caving and overall slip failure of the roof, and the pentagonal section is recommended for the layered rock mass roadway with wedge-shaped caving. The support parameters determined according to the empirical guidelines of Lang T A are generally applicable to the layered rock mass roadway where the arch or wedge shape of such loose block caving occurs on the roof, which may result in less than reasonable parameter design when it is used in the layered rock mass roadway where the overall slip destabilization of the roof occurs. The application of bolt facilitates the formation of stress-balanced arches, thus maintaining the stability of the roadway.
- 1
Study on Pore Structure Characteristics and Gas Adsorption Characteristics of Coal Bodies with Different Buried DepthsAbstract:
In order to study the relationship between the coal pore structure and its gas adsorption performance and different burial depth of the same coal seam, the gas adsorption capacity, pore volume, pore specific surface area and other pore structure parameters of four coal samples were measured by isothermal adsorption experiment and N2 adsorption experiment at low temperature.The pore fractal theory is applied to study the fractal characteristics of different buried deep coal samples, and to determine the relationship between the pore structure parameters and the adsorption constant. The results show that with the increase of buried depth, the pore specific surface area of coal sample increases, and the amount of gas adsorption increases. Among the four coal samples, the pore specific surface area of the deepest buried coal sample increases by 1.2603 m2/g and the pore capacity of the deepest buried coal sample decreases by 0.0026 ml/g compared with that of the shallowest coal sample, the gas adsorption capacity increases by 67%, and the adsorption saturation decreases by 7.4%. The adsorption constants a and b can be expressed by pore structure parameters. The adsorption constant a is positively correlated with the power function of pore specific surface area and fractal dimension, and the adsorption constant b follows the adsorption constant a as a power function. Therefore, the gas adsorption performance can be quantified according to the pore structure parameters of coal samples at different burial depths, providing theoretical basis for refining the gas disaster prevention scheme in the same coal seam.
- 1
Study on long-term mechanical characteristics of cemented backfill with graded fine tailingsKou Yunpeng, 韩冲冲, 齐兆军, 宋卫东
Abstract:
In view of the problems such as unclear long-term mechanical properties and unstable strength of the graded fine tailings cemented backfill, uniaxial compression test, shear test and scanning electron microscope test were carried out to study the long-term mechanical properties and strength evolution law of the graded fine tailings cemented backfill from the macro and micro perspective. The results show that the uniaxial compressive strength and shear strength of cemented backfill specimens increase with the increase of cement-sand ratio. With the increase of curing age, the strength of cemented backfill decreases. The average equivalent diameters of cemented tailings particles with different cementitious ratios (1:4, 1:6, 1:8 and 1:10) after curing for 28 days were 1.79μm, 1.9μm, 2.02μm and 2.67μm, respectively. After curing for 60 days, the cemented particles are 2.61μm, 2.9μm, 2.96μm and 3.26μm respectively. The particle equivalent diameter of cemented tailings is negatively correlated with the cement-sand ratio, positively correlated with the curing period, but contrary to the strength change. This study can provide theoretical guidance and scientific basis for the field application of graded fine tailings and the design of filling parameters.
- 1
Experimental Study of Effect of Air-injection Method on Airlift EfficiencyAbstract:
In order to study the influence of different air injection method on air-lift pump , A test site similar to a mining operation site was established, and a controlled single variable method was used to compare the efficiency of sand and solids removal and the related efficiency of operation mode for pneumatic lifting devices with different Operation mode, different Air-injection method and different Sand depth . The experiment shows that in the process of increasing the decline depth, the axial edge intake mode and the vertical center intake mode have different efficiency equivalence points under different immersion ratios, the value of the depth of descent corresponding to the point of equal efficiency also increases with the increase of the submergence ratio. After the efficiency equivalence point, the efficiency of the axial edge intake mode will exceed the efficiency of the vertical center intake mode. In terms of water lifting efficiency, no matter what kind of submersion ratio is under, the efficiency of vertical central intake mode has always occupied a dominant position. In the operation mode, the efficiency of the decreased suction mode is dominant.Different speed of air intake can change the flow pattern in the lift pipe，the poly-bubble flow pattern causes the efficiency to decrease with increasing sand depth.
- 1
Study on the Key Technology of Strengthening Mining Safety Prevention and Control in the Late Expansion of Deep Open Pit MineAbstract:
Safe extraction of some hanging wall ores at the end of deep open pit mining can bring huge economic benefits to mining enterprises. Taking the deep slope expansion project of Shandak copper gold mine as the research background, the slope stability of the slope expansion mining project is studied by using the simplified Bishop method and Morgen Prince method, and the slope failure probability is analyzed by using Monte Carlo method to determine the safety risk of the slope expansion project. A three-dimensional on-line monitoring system of deep micro earthquake + shallow three-dimensional laser scanning slope stability in the process of expanding mining is established, and the micro and macro deformation evolution mechanism of slope rock mass in the process of expanding mining is studied. The research results show that the results of slope safety risk analysis and three-dimensional on-line monitoring of slope are highly coupled and consistent, which can not only confirm the rationality of the research results, but also provide a theoretical basis and safety guarantee for the end-stage slope expansion and enhanced mining under the same conditions.
- 1
LSTM pressure prediction model based on Optuna optimization method researchAbstract:
Effective and accurate prediction of mine pressure at the working face has important guiding significance for reducing roof disaster and safe production. In order to improve the accuracy of mine pressure prediction, a Long Short Time Memory (LSTM) model mine pressure prediction method based on Optuna optimization was proposed. Firstly, the linearly interpolated mine pressure data were reduced by median filtering algorithm, then the hyperparameters affecting the accuracy of LSTM model were optimized by Optuna framework. The mean square error (MSE) was used to evaluate the model, and finally the predicted mine pressure was compared with the real mine pressure. The results show that the learning rate has the greatest influence on the model, accounting for 54%, followed by the number of model layers accounting for 31%; the MSE decreases by 0.01034 and 0.00671 on the training and test sets, respectively, by the Optuna-LSTM model after denoising, which verifies that the LSTM model has a better effect in mine pressure prediction and enables predict the mineral pressure variation effectively.
- 1
Mining Sequence Optimization of Deep Steeply Inclined Large Thick Orebody in Zhulan Iron MineAbstract:
Reasonable order of recovery is the key to safe and efficient recovery of deep ore bodies. In order to determine the optimal return order of the stage open stoping method with subsequent filling of the Zhulan Iron Mine, four kinds of mine recovery methods and three kinds of mine recovery sequence layout schemes in the Zhulan iron ore mine were designed. Using AutoCAD-Midas-FLAC 3D coupled modeling technology, the stress and roof sink displacement changes during the recovery process of each scheme were analyzed. The extent and distribution of the plastic zone after the end of the pan area recovery. The results show that the stress concentration of the recovery sequence scheme of the stope "two mining one by two" and the "central to two wings mining" of the mine in the pan area is low, the change of the sinking displacement of the roof plate is small, the scope and distribution of the plastic zone are good, and the recovery process is simple. It is conducive to improving the stability of the stope and determining the optimal return order. The research results can provide a technical basis for the deep ore body recovery of Zhulan Iron Ore Mine, and can provide reference for the design of the recovery sequence of the same type of mine.
- 1
Mechanical correlation?analysis between open pit backfilling and underground cooperative miningAbstract:
A mine transforms from open-pit mining to underground mining, and backfills the open-pit with tailings before carrying out ecological restoration in the open-pit area. However, it is difficult to quantify the interaction between backfilling of open-pit and underground mining.Firstly, the paper identifies the correlation factors between backfilling and underground mining, and then analyzes the mechanical correlation between backfilling and underground mining based on the theories of rock strata movement, fixed beam and sharp point mutation,finally, the influence of backfilling of open pit on underground goaf and roadway is analyzed by simulating backfilling of open pit.The results show that the mechanical correlation between open pit backfilling and underground mining is limited, and the stress transfer of open pit backfilling will lead to the collapse of mined-out areas near the bottom of the pit, but it has little influence on the stability of deep underground mining area. After the treatment of empty areas at the bottom of the pit and other measures, open pit backfilling can be carried out in collaboration with underground mining.This study has a good reference value for mines that use open pit to absorb solid waste and mine ecological restoration.
- 1
Research on Stress Evolution Laws of Steeply Inclined Fault Parallel to Orebody under Mining ConditionsAbstract:
In metal mines with steeply inclined ore bodies, a fault parallel to the ore bodies are usually developed well under the influence of magmatic mineralization, and fault slip activation has become the main factor restricting the safe production of this type of metal mines. Based on the field test of Jinshandian Iron Mine in Hubei Province, and the fault activation propensity index D as the activation criterion in the discrete element numerical calculation program, this paper analyzes the stress field response characteristics of the fault plane during downward sequential mining of the steep ore body and its influence on the fault slip activation. Research results show that: under the influence of the downward sequential mining of the steep ore body, the general change trends of normal stress and shear stress of faults parallel to ore bodies are basically similar, and the start time of shear stress reduction lags behind the start time of normal stress reduction by one mining sublevel. The activation of steeply inclined fault parallel to ore bodies usually occurs when the active mining level locates 30m~58m below the fault, and the D value in the upper zone of the fault is always maintained at a high level (D >0.4) after the beginning of mining. For the middle and lower part of the fault, the fault activation propensity index D before activation increased significantly, reaching more than 0.4. Finally, through the field investigation of the slip deformation of the fault F4, the effectiveness of this conclusion in judging the activation of the steeply inclined fault parallel to ore body is verified.
- 1
Optimization and Application of Mining Method in a Lead-zinc MineAbstract:
A lead-zinc mine is an underground mining mine that has been in production for many years. It is a thin to medium thick inclined orebody. For many years, it has been mined by upward horizontal cutting and filling method, which is difficult to meet the requirements of mine safety and production capacity due to its poor safety, low production capacity, high labor intensity and poor operating environment. Through the comprehensive study of the mining technical conditions and the actual production of the mine, it is determined to adopt the layout of the panel, the mechanized panel upward drift filling method and the small sublevel open stoping with subsequent filling method, and use large trackless equipment for mining operations. After optimization, safety production is ensured, stope production capacity is improved, labor intensity of workers is reduced and working conditions are improved.
- 1
Thermal Analysis Experiment on Phytic Acid Inhibits Coal Spontaneous CombustionAbstract:
Coal spontaneous combustion(CSC) is a severe thread to coal mine which can cause gas explosion. It is showed that metal elements in coal has obvious catalytic effect on coal spontaneous combustion.Phosphorus-containing compounds are important environmental-friendly inhibitors that can restrain CSC, and have been widely concerned. Based on this, biological phytic acid(PA) with high phosphorus content and metal chelating ability was selected as chemical inhibitor to investigate the inhibition effect of phytic acid on CSC, with three different concentrations, Considering economy and practicability. Using ICP-MS to test the chelate effect of PA to metal elements in coal samples．The characteristic temperature and thermal effects and parameters of raw coal and coal samples with PA treatment were obtained by thermogravimetric-calorimetry analysis(TG/DTG-DSC). The inhibition effect of PA was analyzed. The results show that PA can effectively chelate Ca, Fe, Mg, Mn and other metal elements that promote spontaneous combustion in coal, and the higher the concentration is, the more obvious the chelation effect is. PA delayed the characteristic temperature of coal mass loss. especially temperature range of dynamic coal mass balance of CSC was was raised markedly. The temperature of gropus were activated was increased 20.5℃. The initial /maximum heat release temperature, and reduced the maximum heat release rate /thermal release during CSC, and the
- 1
The overburden structure and support load Analysis of lower working face under gob of contiguous coal seamAbstract:
In view of the complicated overburden structure of the lower coal face under the mined-out area and the difficulty in determining the support load, according to the relationship between the lower coal caving zone and the upper coal caving zone, the lower coal overburden structure is divided into Three types, namely: "Bulk + Block" structure, "Bulk + Masonry Beam + Block" structure and "Block + Bulk + Block" structure models, and apply mechanics to different types of overlying rock structures The relationship between "support-surrounding rock" is analyzed, the force source of the support is determined, the calculation method of the support"s working resistance is obtained and the corresponding calculation formula is given. The reliability of the formula is verified by the mining practice of 12402 working face in Shigetai Coal Mine.
- 1
Research on creep characteristics of deep high stress surrounding rock and optimization of supporting support technologyAbstract:
In order to solve the support problem of the surrounding rock of a deep roadway in a mine, the research is carried out by means of field experiments, indoor experiments and numerical simulations. Three measuring points are arranged in the 1031m middle section of the mine to obtain magnitude and direction of in-situ stress. Sampling of three typical surrounding rocks(Datang group, Baizuo group and Maping group)in the middle section, mechanical tests were carried out to obtain the mechanical parameters of the rock. In addition, the mechanical parameters are modified by Hoek-Brown criterion and corresponding design specifications to obtain mechanical parameters of engineering rock mass. Creep experiments are carried out on three types of surrounding rocks. It is obtained that best support time is 16h, 8h and 1H respectively when the in-situ stress is 45MPa. Numerical simulation and parameter optimization of three main support forms (concrete support, anchor bolt support and anchor mesh shotcrete support) are carried out with the help of FLAC3D. The results show that surrounding rock of Datang group should be supported by concrete (spraying thickness 50~80 mm) or bolt support (row spacing between bolts 0.8×0.8m ~1.0×1.0m). Baizuo group should be supported by concrete or anchor net shotcrete (spraying thickness 80-100mm, row spacing between bolts 0.8×0.8m). And bolt net shotcrete support (spray thickness 100mm, row spacing between bolts 0.6×0.6m) should be adopted for Maping group
- 1
Study on the Influence of Weak Interlayer on the Stability of Surrounding Rock in Deep Roadway RoofAbstract:
In order to study the influence of roof weak interlayer on the stability of surrounding rock of deep roadway, the thickness, position and number of weak interlayer in the roof were systematically studied by theoretical analysis and numerical simulation. The results show that: 1) the roof is simplified as a composite system composed of elastic body and Nishihara model, which can better describe the roof deformation, and when the stress of weak interlayer is greater than the yield stress, it is prone to instability and caving; 2) When there is a weak interlayer in the roof, it has a certain stress weakening effect on the roof, and there is an obvious stress jump phenomenon at the position of the weak interlayer. With the increase of the number of interlayers, the stress concentration of the floor increases slightly; 3) When the weak interlayer is distributed in the roof, the interlayer close to the roof has a great influence on the deformation of the surrounding rock of the roadway, and there is a deformation mutation in the position of the weak interlayer, which is prone to separation. Combined with the numerical simulation results, when there is a weak interlayer, supporting measures should be taken in time to prevent the instability of the weak interlayer after exceeding the yield stress.
- 1
Numerical Simulation Study on Safety of Artificial False Roof in Downward DriftAbstract:
In the process of downward drift stoping, the stability of its artificial false roof is an important factor to ensure the safety of downward drift stope. By analyzing the stress of artificial false roof in the downward drift stope of Sanshandao Gold Mine, combined with the thin plate theory, the function curve of artificial false roof thickness and compressive strength is calculated, and the appropriate thickness and strength of artificial false roof are obtained, that is, the thickness of artificial false roof is 0.8m, and the strength is not less than 1.5MPa. Combined with field application, FLAC3D numerical simulation software is used to analyze the distribution law of artificial false roof stress field, displacement field and plastic zone before and after mining in downward drift stope. The results show that the artificial false roof with a thickness of 0.8m can maintain stability during the mining process of the downward drift stope and ensure the safety of the lower stope. The research results can provide a theoretical basis for the design and construction of the artificial false roof of the downward drift of the mine.
- 1
Study on Mining Method Optimization and Stope Stability ofAbstract:
Due to its non-renewable nature, phosphate rock has become an important strategic mineral resource in China, but its occurrence condition is poor and mining is difficult. In order to further recover the phosphate resources left by the early mining and solve the roof accidents in underground phosphate mining, it is proposed to optimize the underground mining method of phosphate mine. Occurrence conditions and ore body mining situation preliminary design three kinds of mining method, through the AHP method and entropy weight method in safety, technology and economy three aspects, such as a comprehensive analysis, select pre-cut top room and pillar is made between flat-back cut and fill stoping as I ore mining area in northern segment close after optimizing the mining method of multi-layer phosphate rock, The designed stope chamber is 277 m long, 8 m wide and 5 m high. FLAC3D simulation software is used to analyze and calculate the stability of mined-out area of each horizontal mine room. The calculation results show that the stability of mined-out area formed by the optimized mining method is better under different mining conditions, which further verifies the feasibility of the optimized mining method.
- 1
INFLUENCE OF CONTACT MODE ON FLUIDITY OF STORED MATERIALS AND SIDEWALL PRESSURE IN OREPASSAbstract:
The fluidity of the stored materials in the orepass has a great influence on the blockage and the ore drawing at the bottom of the orepass. Using theoretical research and laboratory related experimental phenomenon analysis, the influence of contact of the ore-rock blocks and contact of them with the orepass wall on the fluidity of the stored materials and the sidewall pressure of the orepass is studied. The results show that (1) the complex variability of the geometry and the characteristic scale of the ore-rock blocks makes them contact each other in three ways: point, line and surface contact when they form a particle support structure system under the constraint of the orepass wall. The size of the contact area between the ore-rock blocks and the blocks with the orepass wall determines the influence degree on the fluidity of the ore-rock and the sidewall pressure of the orepass; (2) the rotation of the ore-rock blocks during their movements in the orepass is the fundamental cause of the change in the contact between the ore-rock particles and between the blocks and the orepass wall; (3)the contact mode of the ore-rock particles affects the fluidity of the ore-rock in the orepass by affecting the voidage of the bulk. The larger the contact area, the smaller the void volume of the bulk, and the worse the fluidity of the ore-rock bulk; (4) the contact mode between the ore-rock block and the orepass wall affects the sidewall pressure of the orepass, and then affects the wear and damage degree of the orepass wall. Under the same sidewall pressure, the damage degree of the orepass wall by point contact is the largest, and the damage degree of surface contact is the smallest.
- 1
Research on the stress and displacement of coal pillar roof after pressure relief by roof cutting of lateral structureAbstract:
In order to study the roof stress and displacement evolution law of the side cantilever cut top coal pillar along the goaf. Taking the lateral roof cutting of 113105 working face of a mine as the research background, the stress distribution and displacement evolution law of coal pillar roof after roof cutting are studied by means of theoretical analysis, numerical simulation and field monitoring. The mechanical model of coal pillar roof after roof cutting is established based on elastic mechanics, and the expression of stress and displacement of coal pillar roof after roof cutting is derived by using difference method. FLAC3D and 3DEC software are used to simulate the stress distribution and displacement evolution characteristics of coal pillar roof before and after roof cutting. The simulation results show that the stress of coal pillar roof is reduced by 18.2MPa, the roof subsidence displacement is 9cm, and the pressure relief rate is 26%~40%. Through on-site monitoring, the stress distribution of the roof above the coal pillar shows a trend of first increasing and then decreasing. The stress reaches the maximum at 20~30m away from the working face and maintains a period of stress concentration. Then the stress decreases and remains unchanged after 65~70m away from the working face.
- 1
RESEARCH AND INDUSTRIAL APPLICATION OF NEW CEMENTITIOUS MATERIALS IN COAL MINESAbstract:
：In order to solve the problem of high energy consumption and high cost of cement as a mine filling cementitious material, for the filling and mining of Liangjia Coal Mine, orthogonal tests were conducted with desulfurized gypsum, cement, slag and excitatant as raw materials, the optimal ratio of new cementitious materials in coal mines was studied, and the strength comparison experiment and underground filling test of new cementitious materials and cement were carried out. The results showed that the optimal ratio of the new filling cementitious material in the coal mine was desulfurized gypsum: cement: excitant: slag = 6:4:3:37, and the strength of the filler 3d, 7d and 28d strengths could reach 3.16MPa, 4.65MPa and 5.52MPa, respectively; The compressive strength of the new cementitious material test block under the same rubber sand ratio conditions is 1.8 times, 1.31 times and 1.26 times the strength of the cement test block, respectively, and the filling test is determined to reduce the new cement material by 17%, and the filling test proves that the new cement material has better early strength and fluidity than the traditional cement material, which can replace cement for filling and mining, which has good economic and social benefits.
- 1
Research on Influencing Factors of Miners" Safety Behavior in Intelligent Coal Mine- Based on Grounded TheoryAbstract:
Miners safety behavior management is an important part of establishing an intelligent coal mine safety management system. In this paper, using the rooted theory research method, a model of miner safety behavior influencing factors in intelligent coal mines containing 7 main categories and 15 sub-categories is constructed, and the variability of influencing factors in different working surfaces is identified. The results indicate that：The safety behavior choices of intelligent miners in coal mines are influenced by miners" external environmental factors (work characteristics, organizational system, subjective norms and technical support) and internal psychological factors (cognitive factors and psycho-emotional). Compared to traditional working faces, the differences in the main influencing factors of miners" safety behavior in intelligent working faces are manifested in increased cerebral workload, increased work skill requirements, reduced man-machine matching, and reduced technical trust and perceived control. This paper provides a theoretical reference for improving the management mode of miners" safety behavior in the construction of intelligent coal mines.
- 1
Low Temperature Reverse Flotation of Iron Ore Using Synergistic Effect of Composite CollectorAbstract:
A composite collector composed of nonionic polyoxyethylene surfactant and fatty acids with acid value 165 and iodine value 110 was prepared. The synergistic effect of the composite collector was studied from the aspects of infrared spectroscopy, mineral Zeta potential measurement and contact angle.According to the mineral characteristics of high fluorine and low silicon, the closed circuit test of one roughing, two cleaning and one scavenging was carried out. The concentrate grade was 66.25 %, which was 0.63 percentage points higher than the field, and the fluorine content of the concentrate was 0.38 %, which was 1.93 percentage points lower than the field.The results of infrared spectroscopy showed that the C-O bond in the composite collector could stably adsorb chemically on the activated fluorite surface. The Zeta potential measurement of minerals showed that the hydrophobic fatty acid calcium formed by fatty acid radical ions and calcium ions was adsorbed on the surface of fluorite, which promoted the flotation of minerals. The contact angle measurement showed that the contact angle of fluorite increased from 50.50° to 77.43°, indicating that the hydrophobicity was enhanced, which was beneficial to the flotation of fluorite. The experiment proved that the composite collector had good collection effect on fluorite, which was of guiding significance for the low-temperature reverse flotation of focused iron ore.
- 1
Study on the performance of tailings hydraulic transport based on ring tube experimentAbstract:
Long-distance tailings transportation is the core of tailings hydraulic transportation, which focuses on ensuring the homogeneous transmission of tailings transportation process of material propeller and determining the resistance loss of material propeller in the pipeline.Through the analysis of the material, the slurry sedimentation experiment and the sliding Angle and the experiment of the tailings in Sichuan province, determine the transmission parameters and verify the transmission feasibility of the tailings.The results show that: 1) tailings grading is relatively good, stable material composition, no or less toxic element minerals, can be used for normal pipeline transportation.2) The tailings slurry has large yield stress and small dynamic viscosity, and the tailings conveying concentration is recommended to be 52% -56%.3) At the pipe diameter (125mm, 140mm, 180mm), the recommended operating flow rate is 2 m/s, and the pipeline resistance loss range is 3.148×10-2MPa / km~3.618×10-2MPa / km.The research results can provide a basis for the design of mine tailings pipeline transportation.
- 1
Significance of Anisotropy to Gas Migration and Drainage Borehole Layout in Coal SeamsAbstract:
reasonable and accurate borehole spacing is an important parameter that affects the gas migration in coal seams and controls the gas drainage to reach the standard. In order to clarify the influence of permeability anisotropy on the spatio-temporal evolution of coal seam gas, the permeability anisotropy characterization method based on the equivalent displacement principle is used to analyze the influence of permeability anisotropy coefficient on the spatio-temporal evolution of gas migration field by establishing and verifying the fluid solid coupling model of non free space vector dual porous media. The results show that the gas pressure and permeability at the equidistant position of the borehole are distributed in vertical and horizontal "8" shape respectively, and the shrinkage degree in the middle is directly proportional to the anisotropy coefficient; A larger anisotropy coefficient corresponds to a larger matrix fracture pressure difference, which does not
- 1
DESIGN OF SAFETY PERFORMANCE TEST SYSTEM FOR CONTROL DEVICE OF MINE ELECTRIC LOCOMOTIVEAbstract:
Electric locomotive is an important transportation equipment in underground mine. Its control device is mainly used for power supply, speed regulation and electrical safety protection of electric locomotive. It is the core component of electric locomotive. Its safety and reliability directly affect the safety of underground mine. According to the requirements of safety performance test for the control device of mine electric locomotive, a safety performance test system based on AFE four quadrant rectification and reversible dc/dc voltage regulation technology is designed, and a high-precision data acquisition unit is developed to realize the rapid and accurate acquisition of test parameters.Through measurement calibration and laboratory function verification, the test results show that the test system meets the safety performance test capabilities such as temperature rise, on and off, overload capacity, protection and conduction ratio, and the system has the advantages of high measurement accuracy, wide application range and high integration.
- 1
Study on Stress Distribution Low for Roadway Near the Coal Seam under GoafAbstract:
It is very important to grasp the stress distribution law of surrounding rock for the safe mining of coal. Numerical simulations were carried out on the excavation of the lower roadway in the goaf area of Shuiyu Mine and the process of working surface recovery, and the vertical stress distribution law of the surrounding rock in the working surface recovery process with or without the upper goaf area was compared and analyzed, and the deformation mechanism and control measures of the surrounding rock in the lower goaf area were proposed. The results show that: When there is a goaf in the upper layer, the stress field distribution at the roadway is changed from "U" to "V" type, and the vertical stress of the two gangs of the roadway is greater; the working surface and the excavation area of the roadway form an "L" type stress release area during the recovery process, and a significant stress concentration is generated in the intersection part. The variation range of the stress concentration coefficient of the advanced support pressure is 1.773~1.829, the distance between the peak stress and the working surface is 1.5 to 3 .8m, the variation range of the stress concentration coefficient of the lateral support pressure is 1.441~1.698, and the distance between the stress peak and the working surface is about 12.5m. Compared with the case of no goaf area, the vertical stress of the working surface and the roadway is greater, and the study can provide a reference for the selection of the roadway location and the optimization of support.
- 1
Comparison and Optimization of Stope Structure Parameters in Ashele Copper ore Body Based on Analytic Hierarchy ProcessAbstract:
ABSTRACT:In order to optimize the stope structure of Ashele copper ore body in Xinjiang, firstly, the geology and hydrology of the mining area are described; Secondly, the method of analytic hierarchy process is used to study the rock mass in this area; Finally, the comparison is made from different mining widths and mining sequences. The results show that among the ore rock, basalt, tuff and quartzite porphyry in Ashele copper mine area, the quality of tuff is general, and the quality of ore rock, basalt and quartzite porphyry is relatively good. Taking the stope models of 10m, 13m, 16m and 19m stopes as the research object, through the comparison of the numerical results of maximum tensile stress, maximum compressive stress and horizontal displacement, it is known that the structures of the four kinds of stopes are relatively stable, and the structure with 13 stopes is the best. Through the analysis of the mining sequence with a mining width of 13 meters, it is found that the rock mass of the pick one every other and pick one every two has the problem of deformation, and there will be the risk of collapse during mining, and the performance of the pick one every three is the best. Therefore, the comparative optimization of stope structural parameters of Ashele copper ore body based on analytic hierarchy process provides a new theoretical basis and optimization direction for mining in the future.
- 1
Development of Underground Coal Gangue Intelligent Sorting Device Based on Dynamic Weighing and Image Recognition TechnologyAbstract:
The utilization of underground gangue is a key scientific problem that needs to be solved urgently in the field of resources and energy in the 14th Five-Year Plan of China. In view of this problem that needs to be solved, this paper puts forward two new ideas for underground coal gangue separation, i. e., discontinuous coal flow chamber coal gangue separation and continuous coal flow belt coal gangue separation. With intelligent image recognition and dynamic weighing technology as the core, the compact coal gangue separation device suitable for underground chamber separation and the distributed coal gangue separation device suitable for the trough or roadway are designed. The former uses a multi-stage screen structure to make up for the influence of particle size difference on object recognition, and uses a large angle conveyor belt to effectively reduce the size of the equipment. The latter uses small pulleys as the conversion medium of the main power of raw material transportation in the device, which reduces energy consumption. The coal gangue identification and sorting are processed in parallel through the turntable device, and the work efficiency is improved. The research and development of the device has certain significance to promote green coal mining.
- 1
Application of Improved LR Algorithm in Classification of Turbidity of Slurry Screen WaterAbstract:
Aiming at the problem of turbidity discrimination of slurry screening water in the offline screening method of traditional pulp fineness detection, in order to develop the automatic detection technology of fineness, an improved LR (Logistic Regression) algorithm is proposed to classify the turbidity of slurry sieving water. Firstly, the slurry sieving water image is collected, and the turbidity information data set of the sieved water image is obtained by using the slurry turbidity information extraction algorithm; secondly, the shortcomings of the traditional LR algorithm are analyzed, and an improved LR algorithm is proposed; finally, the improved LR algorithm is applied to the classification of the turbidity information data set. The results show that the feature parameters of the slurry screen water image are extracted by the RGB based turbidity information extraction algorithm. After the improvement of the logistic regression algorithm by L2 regularization, its indexes are optimized compared with other algorithms, and it has the best classification effect on the turbidity classification of the slurry screen water.
- 1
Research and application of safety technology for the whole life cycle of electromechanical equipment in non-coal underground minesAbstract:
Electromechanical equipment is an important link for safe and efficient mining of metal and non-metal underground mines, and its safety performance directly affects the normal production of mines. Aiming at the technical characteristics and use characteristics of electromechanical equipment in metal and non-metal underground mines, the safety technical requirements for the safe access, safe use and exit of electromechanical equipment are studied, and the complete set of solutions for each link is studied in depth with typical cases. , and reached the following conclusions: in the safety access stage, it is necessary to ensure that the mechanical and electrical equipment meets the requirements of design and acceptance, and purchase products with mining product safety marks in accordance with relevant regulations; in the use stage, it is necessary to standardize daily inspections and regular inspections. In accordance with the criteria for determining potential hazards of major accidents and the catalogue of prohibited equipment and processes, the company conducts hidden danger investigations, timely rectifies equipment with potential accident hazards, and eliminates outdated equipment, providing technical support for the safe use of electromechanical equipment throughout the life cycle of mining enterprises.
- 1
Research on Microwave Irradiation Selective Heating Experimental and Feasibility Study with Ore Concentration Using Color Sorting of A Copper-Nickel MineAbstract:
With the gradual decline of production ore grade, it is of great significance to realize the ore concentration for reducing cost and increasing efficiency of mine production and comprehensive utilization of mineral resources. To explore the feasibility of microwave technology application in the ore concentration, based on the choice of microwave irradiation with different mineral heating mechanism, was variable with time and power, of a copper nickel ore and waste rock samples, the experimental study on ore samples with waste rock samples under different power and time of microwave irradiation was performed and the change of the temperature distribution in the differences were analyzed. The results show that under different microwave irradiation power and irradiation time, the ore and waste rock of the copper and nickel ore show obvious difference in color temperature, which has a good intuitive recognition feature. The temperature change of the ore sample is positively correlated with microwave irradiation power and irradiation time. It further shows that microwave technology can be used to distinguish the ore and waste rock in the copper-nickel mine. combining with artificial intelligence image recognition means, a new image color sorting ore preconcentration technology can be formed.
- 1
Prediction of Mine Water Inflow Based on Deep Confidence NetworkAbstract:
In the process of mine mining, accurate prediction of mine water inflow is of great significance for mine water control and efficient and safe production. Aiming at the problem of insufficient prediction accuracy due to the complex influencing factors of mine water inflow, a method for indirect prediction of mine water inflow based on Deep Belief Network (DBN) was proposed. First, the corresponding DBN water inflow prediction models are established for different panels, and then the water inflow data is extracted from the water silos of each panel in the mine, and then the DBN prediction models are imported respectively for prediction, and the water inflow of each panel is obtained. water flow. At the same time, the results are compared with the prediction results obtained by BP, ELM neural network and DBN directly predicting mine water inflow. The test results show that the DBN indirect prediction has the highest prediction accuracy, indicating that the DBN indirect prediction model of mine water inflow established in this paper has a better prediction effect, and provides a new method for accurate prediction of mine water inflow.
- 1
Experimental Study on Deep Sandstone under Dry-wet Circulation Resistance to Acid and Alkali Erosion Performancezhanjiajia, 庞建勇, 徐飞凡, 姚韦靖
Abstract:
In order to solve the problem in the process of deep mining groundwater effect on the rock mass and the harm caused by the deep engineering security and stability problems, experimental study was finished on deep sandstone which in sheet sets Huainan mining area. Studied its acidity(pH=3), neutral(pH=7), alkali(pH=11) experience multiple dry-wet circulation in the solution process of the erosion resistance, and comprehensively analyzed internal damage and degradation mechanism of sandstone material in sample appearance form, mass loss, uniaxial stress parameters as evaluation indicators and combined with the ultrasonic testing technology. The results show that, with the increase of dry-wet cycles, sandstone sample mass loss increases gradually, less dense degree, and the peak stress, elastic modulus, the decline of the compressional wave velocity have obvious phenomenon, sandstone sample degradation suffered varying degrees of damage. But the increase of peak strain means sandstone samples are softening, brittle get good improvement. Under the same cycles, acid and alkaline solution contributes to the destruction of the sandstone sample process is more significant. Experimental phenomena show that the dry-wet circulation, acid and alkaline solution erosion coupled negative mutual promotion of the sandstone sample damage degradation expanded.
- 1
Effect of T-M-pH Mixing Water on the Strength of Filled Paste and Prediction ModelAbstract:
In order to investigate the effect of initial temperature, mineralization and pH of mixing water on the performance of filling paste under coupled conditions, a 3-factor 4-level orthogonal test was designed to configure mixing water with different initial temperatures (5℃, 15℃, 25℃, 35℃), mineralization (0mg/L, 1000mg/L, 2000mg/L, 3000mg/L) and pH (3, 5, 7, 9) to make The results were analyzed by extreme difference analysis to determine the significance of the factors: mineralization > acidity > initial temperature, and the optimal combination was determined after comprehensive comparison: initial temperature 25℃, mineralization 2000mg/L, acidity 5. The acidity and initial temperature were kept constant in the optimal combination, and the mineralization was changed 10 sets of tests were carried out, and the uniaxial compressive strength combination prediction model was constructed by combining gray prediction, fuzzy classification and Markov theory with experimental data as the original data. 3 groups of experiments were carried out according to the gradient to compare the two prediction models. The results show that the combined prediction model is more accurate and stable than the gray GM (1, 2) prediction model.
- 1
ESG Performance, Financing Constraints and High Quality Innovation of Coal Companies under "Double Carbon" TargetAbstract:
In order to investigate whether Chinese coal companies can reduce financing constraints by improving ESG performance under the constraint of the "double carbon" target, and thus drive the realization of high quality innovation. Based on the theoretical analysis and research hypothesis, the panel data of listed coal companies from 2010 to 2020 was used as the research sample to empirically test the relationship between ESG performance, financing constraints and high quality innovation through the dimensions of intensity, persistence and efficiency. The results show that ESG performance of coal companies significantly and positively affects innovation investment intensity, innovation persistence and innovation efficiency, ESG performance of coal companies significantly and positively affects high quality innovation, while financing constraints play a mediating effect in this influence process, and it is a partial mediating effect. Further, the findings remain valid after replacing the metrics, robustness test of the mediating effect and endogeneity test. Therefore, establish ESG concept and actively participate in ESG practice are one of the scientific paths for coal companies to achieve high quality innovation.
- 1
Study on the Influence of Crack Property on The Rock Mass Compressive Mechanical Behavior with Extended Finite Element MethodAbstract:
The existing analyses on the compressive mechanical properties of rock mass with non-persistent cracks neglect the crack deformation parameters. The strain softening model in ABAQUS is used to describe the rock mechanical behavior. The extended finite element method (XFEM) is adopted to calculate the crack propagation path. The analysis mainly focuses on the effect of crack geometry parameters (length, dip angle, interval, center distance and number), strength parameters (friction coefficient), deformation parameters (normal stiffness and tangential stiffness) and confining pressure on crack propagation path and rock material mechanical behavior under compression. The results show that the rock mass uniaxial compressive strength and elastic modulus decrease with increasing crack length and number. With increasing crack center distance and row spacing, the compressive strength and elastic modulus of the samples increase. The rock material compressive strength increases with increasing confining pressure, crack friction coefficient, crack normal and tangential stiffness. Finally, with the crack inclination angle increasing from 0° to 75°, the rock mass uniaxial compressive strength firstly decreases and then increases, and the minimum compressive strength is obtained when the crack inclination angle is 45o, which shows a parabolic change law with hatch toward up. The crack length, dip angle, number, interval, center distance and confining pressure have much influence on crack propagation path.
- 1
Effects of iron ore tailings on concrete strength and sulfatefreeze-thaw resistanceAbstract:
In order to achieve the goal of cleaner production, iron ore tailings are used as fine aggregate to prepare concrete. The influences of different iron ore tailings replacement ratios on concrete strength and sulfate freezing-thawing resistance are discussed in detail from the macro and micro levels, and the influence mechanism is analyzed. Therefore, 6 kinds of concrete are prepared. Namely, the replacement ratios iron ore tailings of 0%, 20%, 40%, 60%, 80% and 100%. The results show that when the replacement rate of iron ore tailings is low, the inner microstructure of concrete is compact, which has a positive effect on its strength and sulfate freezing-thawing resistance. But, when the replacement rate is too high, the negative effect will be produced. In addition, the relationship between compressive strength and splitting tensile strength is proposed, and the Weibull damage model after freezing-thawing is established. Some parameters are proposed. Finally, it is considered that concrete mixed 40% iron ore tailings are good strength and freezing-thawing resistance.
- 1
Detection of Hydraulic Fracturing Range of High Strata above Coal Face Based on Seismic Frequency ResonanceAbstract:
The pre-fracturing of the high hard strata overlying the coal face can weaken the energy storage conditions and control the energy of mine earthquake events. In order to detect the spatial distribution of fractures caused by hydraulic fracturing in high strata of coal mining face with buried depth over 500 m, the three-component seismic frequency resonance technology is used to detect the spatial distribution of fractures. Six frequency resonant detector lines are designed. Tests are performed before and after hydraulic fracturing operations. The detector waveform data obtained are interpreted. The results of data interpretation show that :(1) the spatial distribution of hydraulic fracturing fractures is ellipsoidal, and its long axis is basically consistent with the direction of the maximum principal stress of the strata; (2) The maximum fracturing radius in the horizontal direction can reach 50 m or more, and the fracturing height in the vertical direction can reach 30-50 m; (3) The stress reduction region formed by hydraulic fracturing is much larger than the crack growth region; (4) The crack propagation of hydraulic fracturing is greatly affected by the occurrence of rock strata. The research shows that the three-component seismic frequency resonance technology can effectively detect the spatial distribution of hydraulic fracturing fractures in deep rock strata, and it is a suitable method for the detection of hydraulic fracturing range.
- 1
Optimization Study of Mining Sequence Based onImproved CRITIC- TOPSIS ModelAbstract:
Reasonable mining sequence has an important impact on stope stability and mining efficiency. Taking an iron mine in Gushan, Anhui Province as the background, four different mining schemes are proposed. The mining model is constructed by the Rhinoceros/griddle coupling method, and the stress field, displacement field and plastic failure under the conditions of different mining schemes are simulated and studied based on FLAC3D software. Each mining scheme is optimized based on an improved CRITIC-TOPSIS model, and the results show that the maximum principal stress and maximum tensile stress of the stope have large fluctuations in primary stopes, and the stress field tends to be stable at a low level in secondary stopes. As the sequence progresses, the subsidence displacement of the roof and the bulging displacement of the bottom plate of each mining plan gradually increase, and reach the maximum value in the last step. The rock mass failure in primary stopes is mainly shear failure, and the tensile failure in secondary stopes begins to appear. The relative closeness order of each scheme is: scheme 2> scheme 1> scheme 3> scheme 1, the optimal mining sequence is the one every other mining from the center to the two wings, which is consistent with the intuitive results of the distribution characteristics of the plastic failure zone.
- 1
Technical research on the rib pillar recycling of underhand cut-and-fill without sublevel stopingAbstract:
When adopting the underhand cut-and-fill without sublevel stoping method to extract the steeply inclined thin orebody in which both the peripheral rocks and the minerals are extremely unstable, it is necessary to lay the reinforcement mesh in the overlying backfill in advance, and to drive the long anchor bolts with a certain row spacing into the adjacent rib pillars, in order to ensure the stability of the overlying backfill in the stope. The application of this method will lead to the impossibility of recovery of the ore body in the rib pillar, which makes a higher ore loss rate. Given the fact that rib pillar cannot be recovered when using the underhand cut-and-fill without sublevel stoping method, a novel rib pillar recovery technology is proposed in the current study to improve the original method. First, the recovery scheme of rib pillar and arrange of overlying backfill in the stope is briefly introduced. Then the economic comparison and analysis of the mining scheme are carried out to verify the rationality and applicability of the technical scheme on the basis of a specific underground metal mine. The research indicates that the proposed method can not only recover the rib pillar on both sides of the stope, but also form the embedded beam structure of overlying backfill which depends on the bilateral filling body, long bolts and reinforcing mesh, so as to improve the resource recovery rate and ensure the stability of the false roof.
- 1
Research on pressure relief angle of side structure roof cutting of gob side entryAbstract:
Roof cutting and pressure relief is a common method to control roadway deformation. In view of the restricted cutting height of the aquifer, the lateral cantilever of the return air trough and the roof condition of the thick and hard aquifer in the 113105 working face of BoJiang Haizi coalmine are taken as the background. By means of theoretical analysis, numerical simulation and field industrial test, the reasonable angle parameters of aquifer roof lateral cantilever roof cutting pressure relief are studied. The mechanical model of roadway pillar after roof cutting is established, and the stress distribution formula of pillar after roof cutting at different angles is derived. Using ANSYS/LS-DYNA to simulate roof cutting at different angles. The results show that the degree of rock damage and fracture development is different under differentroof cutting angles, and the stress of coal pillar is reduced after roof cutting. When the cutting angle is 85 ° ~60 °, the vertical stress of the coal pillar presents a "Hump" trend, the vertical stress peak at 3m is larger, and the bimodal value decreases with the increase of the cutting angle. After 55 ° and 50 ° roof cutting, the peak value of vertical stress at 3m of the peak point of coal pillar stress is less than that at 7m of the peak point, and the double peak value increases with the decrease of roof cutting angle. The field test shows that the stress of surrounding rock is obviously reduced after the roof cutting according to the designed angle, the deformation degree of roadway structure can meet the normal mining demand of the working face, and the pressure relief effect is remarkable.
- 1
Risk Assessment of Filling Pipeline Wear Based on SPA —Unascertained Measure ModelAbstract:
In view of the fuzziness of filling pipeline wear rating, the dual theories of SPA and unascertained measure are introduced to construct the SPA unascertained measure pipeline wear prediction model. Taking five mines in China as examples, 11 qualitative and quantitative influencing factors such as filling slurry concentration are selected to establish the filling pipeline wear evaluation system. In order to overcome the subjectivity of SPA using expert scoring to determine the evaluation grade, integrate the unascertained measure, establish a single index measurement function, and calculate the filling pipeline wear grade and change trend of different mines in combination with the weight coefficient of each index and SPA connection degree component. Through calculation, the wear grade of filling pipeline in five mines is grade II, which is consistent with the actual situation, which verifies the feasibility of the model and provides a new method for filling pipeline wear evaluation.
- 1
Upper Limit Analysis of Dynamic Stability of Tunnel Face under Earthquake Force Based on Quasi-Static MethodAbstract:
Earthquake is one of the causes of underground engineering disasters. It is of great significance to study the stability of tunnel face under the influence of earthquake. In this paper, according to the limit analysis, Baker strength criterion and quasi-static method are used to describe the influence of soil strength and seismic force respectively, and the stability of tunnel face is calculated and analyzed. In addition, comparative analysis and parameter analysis are also carried out. The research results show that: (1) The calculation results of this paper are close to the research results of other scholars, and the maximum error does not exceed 6%. The theoretical calculation formula of this paper is reasonable and correct, and can be used in practice. (2) The surrounding rock pressure decreases nonlinearly with the increase of A. When A<0.5, the surrounding rock pressure decreases with the increase of n, and when A>0.5, the surrounding rock pressure increases with the increase of n. The surrounding rock pressure has a linear decreasing relationship with the parameter T, and a linear increasing relationship with the horizontal and vertical seismic acceleration coefficients kh and kv. (4) When A, n or T decreases, the damage area in front of the tunnel face increases, and the parameter A has the most obvious effect, n is the second, and T is less obvious; when kh and kv increase, the damage area in front of the tunnel face also increases
- 1
Application Status and Prospects of MWD Technology in Non-oil and Gas Engineering FieldAbstract:
Measurement While Drilling (MWD) technology has broad application prospects in mining engineering and other industries. However, there is a lack of research and application of MWD technology in non-oil and gas engineering field in China. This paper introduces the development process of MWD technology, and analyzes the composition and basic principle of MWD system. Next, the commonly used methods of data processing in MWD are summarized. Then, the applications of MWD technology in the field of non-oil and gas are systematically evaluated, which include the prediction of rate of penetration, the determination of rock mass mechanical parameters, the identification of rock mass structure parameters, the delineation of ore body contour, the support design decision-making, and the blastability evaluation. Finally, this paper summarizes the problems existing in the field of MWD technology, and looks forward to its future development direction.
- 1
Experimental Study on Temperature Effect of Remote Sensing Laser Methane Detector in Coal MineAbstract:
The remote sensing laser methane detector for coal mines is used to monitor the gas concentration in underground mines. The measurement accuracy is easily affected by changes in ambient temperature. The personal safety of underground operators is directly affects. Based on analyzing the measurement principle of the remote-sensing laser methane detector, the temperature control technology of the semiconductor refrigerator is used, the fuzzy PID temperature compensation algorithm with Smith prediction algorithm is also applied. So the anti-interference of the remote-sensing laser methane detector to temperature changes is effectively improved. The performance is verified by experiments. The results show that: Before the optimization of temperature compensation, the maximum relative error of the sample measurement under the ambient temperature of 0℃ ~ 40℃ reaches 13.98%. With the increase of temperature, it shows an obvious increasing trend. However, after the temperature compensation, the maximum relative error of the sample measurement is only 3.91%. The measurement accuracy is significantly improved.
- 1
Comprehensive Consideration of Low-carbon and Low-cost Truck Transportation Optimization Research in Open Pit MinesAbstract:
The mining industry is one of the typical industries with high energy consumption and high carbon emissions, and it is also an important source of energy carbon emissions in my country. Carbon emissions endanger environmental safety and public health. Aiming at the truck transportation problem in open pit mines, this paper takes reducing carbon emissions and saving transportation costs as two optimization goals, and establishes a multi-objective linear programming mathematical model about 17 loading points and 4 unloading points. Using MATLAB software and traditional The linear programming method and the NSGA-II method are used to solve the mathematical model, respectively, and the calculation results of the model considering low-carbon conditions were compared with the actual results without considering low-carbon conditions. The research results show that the comprehensive consideration of low-carbon and low-cost transportation model research can not only improve economic benefits, but also reduce carbon emissions in mining truck transportation. Therefore, it is of great significance to take the reduction of carbon emissions as one of the optimization goals to plan when studying the planning of mining truck transportation.
- 1
Measurement Method of Discontinuity Trace Occurrence Based on Double Image InterpretationAbstract:
The discontinuity occurrence is important geological information. There are usually two types of rock mass discontinuity exposure: linear structure and planar structure. Aiming at the problem that the geological compass and point cloud analysis can not effectively measure the occurrence of discontinuities exposed as linear structure, this paper takes the excavation face of an underground metal mine roadway as the research object, and proposes a discontinuity trace occurrence measurement method based on double image interpretation. Firstly, two images of rock mass to be measured are taken from two different perspectives. Secondly, the discontinuity traces in one of the images are identified by searching the minimum cost path, and several anchor points are arranged along each discontinuity trace. Then, collinear equation is used to solve the 3D coordinates of all anchor points after matching the corresponding image points. Finally, the least square plane fitting method is used to determine the equation of discontinuity plane and the discontinuity occurrence is calculated according to the plane normal vector. The reliability and practicability of the proposed method are verified by comparing the measurement results of the proposed method and the Sirovision system. The research results can provide reference for more detailed and reliable discontinuity investigation.
- 1
Acoustic Emission Test and Numerical Simulation of Similar Coal Samples under Uniaxial CompressionAbstract:
Taking the maintenance and reinforcement of Gengyi track roadway in No. 2 Coal Mine of Pingmei Coal Group Co., Ltd. as the background, the mechanical properties and crack evolution of similar material coal samples in uniaxial compression acoustic emission test were analyzed by uniaxial compression acoustic emission test and particle flow software ( PFC3D ) simulation test similar material coal samples of cement, gypsum and full-size pulverized coal. The results show that the stress-strain curve of coal sample with similar material ratio is similar to that of raw coal, and the failure mode is inclined section shear failure. The stress – strain curve and its failure mode simulated by PFC3D are similar to those of the coal sample, and the crack evolution process is demonstrated by PFC3D model. The research results provide technical guidance for later similar material model test and roadway support.
- 1
RESEARCH AND APPLICATION OF KEY TECHNOLOGY OF LOW COST CEMENTED FILLING IN LARGE MINESAbstract:
In recent years, with the increasingly strict requirements of national safety and environmental protection, more and more underground mining mines have changed to filling mining. To popularize the filling mining method, the filling cost is an important factor affecting the mine decision-making,especially for some large and super large mines with low value and low grade, the filling cost not only has a great impact on the mining cost, but also the annual filling cost is often hundreds of millions of yuan,the pressure of cost control is particularly great when the filling mining method is popularized in such mines. In addition, for large and super large mines, the investment in filling system is also large,how to adopt advanced technology to improve filling capacity and reduce the construction investment of filling system is also the first problem to be considered in popularizing filling mining method in such mines. This paper summarizes the experience in the construction and practice of filling system in large mines in recent years,through the research on high-efficiency concentration of tailings, accurate addition of cement, uniform preparation of paste, long-distance large-scale linear transportation of slurry and high-efficiency cementing agent, the key technology of low-cost cemented filling in large mines has been formed and popularized and applied in many large and super large mines, the slurry preparation and transportation capacity of a single system reaches 180 ~ 200m 3/ h,The filling operation can be carried out continuously for 24 hours, the filling capacity of a single station can meet the requirements of full treatment of the goaf generated by the mining capacity of 5 million t / a, and the filling cost is less than 50 yuan / m 3, the indexes of filling capacity and filling cost are at the leading level in China.
- 1
Study on the Development Law of Cracks in Overlying Coal Based on Fractal TheoryAbstract:
In order to study the development law of cracks in overlying coal mining under close protection layer, taking C8 and C9 coal seams of Xiongjiawan Coal Mine as the research background, fractal theory and numerical simulation were used to analyze the development characteristics of cracks and stress changes in overlying coal mining under close protection layer. The results show that the fractal dimension of the fracture network shows a downward trend, upward trend and stable trend after the mining of C9 protective layer, which represents three stages of fracture development in the overlying coal rock, namely, the development of new cracks from roof caving compaction, the development of roof caving compaction to compaction, and the development of compaction cracks to the overall stability stage. With the advance of working face, the change of stress in overlying coal rock is similar to the fractal dimension of fracture network, which can be used to characterize the change trend of stress. Combined with the empirical calculation formula of "three belts" and numerical simulation results, the fracture development height is about 20 m, higher than the distance between coal seams, and the fracture development in C8 coal seam. The relevant research results can provide reference for the study of the development law of cracks in overlying coal rocks under similar geological conditions in western Guizhou.
- 1
Stress response characteristics of mined-out area based on salamon model and research on reasonable width of coal pillars in sectionsAbstract:
Aiming at the large deformation and control problems of the open roadway, a method is proposed to reduce the roadway deformation by optimizing the reserved width of the coal pillar in the section. Comprehensive theoretical analysis and numerical simulation were used to study the stress distribution characteristics of the goaf and the width of the central stress recovery zone under different coal pillar widths, the distribution pattern and evolution characteristics of the coal pillar load in the section, and combined with the elastic-plastic evolution of the coal pillar in the section. According to the law, determine the reasonable width of the coal pillar in the section. The results show that: ① After double-sided mining, the vertical stress of the Salamon unit in the gob of the first working face has an asymmetric "saddle-shaped" distribution, and with the increase of the width of the coal pillar, the stress peak value gradually decreases from 5.8MPa to 3.9MPa. The stress recovery range of the goaf is reduced from 187m to 162m; while the vertical stress of the gob in the Salamon unit of the goaf of the gob face is distributed in a “spire and arch” shape, and the width of the peak and middle stress recovery zone does not change much; ② With the increase of the width of the coal pillar in the section, the vertical stress distribution shape gradually evolved from "arch" to "saddle", the stress peak value from 37.19MPa gradually decreased to 28.32MPa, and the proportion of elastic core area increased from 3.6% to 62.9%, and taking 40% of the elastic core area as the critical instability criterion of the coal pillar, the reasonable width of the coal pillar is determined to be 20m.
- 1
Active Identification Method of Coal and Gangue by Microwave Irradiation-Infrared DetectionAbstract:
The intelligent mining of longwall top coal caving working face has been restricted by the automatic identification of coal and gangue in the process of top coal caving process. Based on the differences of physical and chemical properties between coal and gangue, a microwave irradiation-infrared detection active coal gangue identification method is proposed. This method actively increases the external thermal difference between coal and gangues by microwave irradiation, and then obtains the difference by infrared detection technology, so as to identify and judge coal and gangue. Under laboratory conditions, this method was used to conduct microwave irradiation experiments on coal and gangue samples from Tongxin Coal Mine. The experimental results show that under the same microwave irradiation conditions, according to the order of particle size from small to large, the temperature rise of coal particles before and after microwave irradiation is 1.3 times, 1.7 times, 2.0 times and 2.3 times of gangue respectively, which verifies the feasibility of this identification method. It provides a technical reference for the automatic identification of coal and gangue in the intelligent top coal caving process of longwall top coal caving working face.
- 1
Theoretical Calculation and Experimental Research of Braking Force on Steel belt Overwinding Buffer DeviceAbstract:
According to the theory of plastic deformation of hardened materials, the general material mechanics conclusion of plastic deformation of long and straight steel belt in rotary straight roll is given, and the mathematical relationship between the influencing factors and brake force is summarized. The analysis shows that when the moving roller and fixed roller are arranged according to the three-roll system, the bending and extrusion of the steel belt and the vertical upward motion are carried out, the braking force of the steel belt is positively related to the thickness of the steel belt, the width of the steel belt, the relative distance between the device and the fixed roller. In order to distinguish the effect of different parameters on the actual brake power of steel belt, the orthogonal method is used to analyze the uniform dispersion difference of different parameters. The results show that the thickness of steel belt plays a leading role in the adjustment of steel belt power. This study provides a reliable basis for the design and selection of mine shaft coiling device.
- 1
Mechanism and Control Technology of Asymmetric Floor Heave in Gob Side EntryAbstract:
The bottom heave control of gob side entry retaining is of great significance to maintain the stability of surrounding rock, improve the success rate of roadway retaining and safe and efficient mining. By means of theoretical analysis, numerical calculation and field measurement, the mechanical model of elastic foundation beam of bottom plate is established, the mechanism and decisive factors of asymmetric bottom heave of bottom plate are studied, and the control measures of bottom heave are put forward. The results show that the deflection and bending moment of the floor directly below the roadway reach the maximum value with the characteristics of non-linear distribution. The floor heave value and asymmetry have a linear positive correlation with the buried depth and concentration coefficient, and a negative exponential correlation with the floor stiffness; The larger bending rigidity of the floor corresponds to the easier fracture in the roadway. The degree of difficulty of floor damage in different areas is: the upper surface of roadway floor > the lower surface of coal pillar floor > the lower surface of solid coal floor. Taking the vertical stress as the root and the horizontal stress as the direct cause, the decisive factor of the floor heave is revealed. Based on this, pressure relief roof cutting and split bolt support control technology are proposed and successfully applied in field practice and the rapid deformation area and magnitude of the floor heave are reduced by 28.6% and 63.5% respectively.
- 1
Research on Interference Source Identification and Suppression Technology of Mine Electromechanical EquipmentAbstract:
With the advancement of intelligent mines in my country, in addition to meeting the basic performance of mine mechanical and electrical equipment, such as its performance, electrical safety and protection performance, and environmental adaptability, its anti-electromagnetic interference performance is also an important guarantee for measuring the safe and reliable operation of mine mechanical and electrical equipment.According to the technical characteristics and usage characteristics of mine electromechanical equipment in my country, through the research on the identification technology of mine interference source and the electromagnetic immunity test technology of existing electromechanical equipment, the radio frequency electromagnetic field radiation immunity and conducted disturbance suitable for mine electromechanical equipment are proposed. Severity levels and test methods for typical immunity tests such as immunity, electrostatic discharge immunity, electrical fast transient burst immunity, and surge (impulse) immunity. According to the principle of immunity test and the three elements of interference formation, shielding technology, filtering technology, isolation technology and circuit optimization design were researched and proposed, which provided technical support for the establishment of electromagnetic compatibility testing, evaluation and standard system of mine mechanical and electrical equipment.
- 1
Research on Permeability Improvement Technology with Through Layer Hydraulic Punching for“Three-Soft”Coal SeamAbstract:
In order to improve the effect of hydraulic punching and antireflection in "Three-Soft" coal seam, the principle and technical difficulties of hydraulic punching and antireflection in "Three- Soft" coal seam are analyzed, the technology of through layer hydraulic punching and antireflection is proposed, and the key links such as the optimization of punching equipment, construction process, slag removal technology, coal water separation technology, hole protection and hole sealing technology are studied. Taking the 二1 coal seam of Mengjin mine as an example, the hydraulic penetration enhancement test of through layer drilling was carried out, and the effect was investigated. The results show that after punching, the diameter of the borehole is expanded by 8.14~12.40 times, the coal washing capacity of a single hole is between 6.3~ 4.4t, the gas pressure of the coal seam within the influence range of punching is reduced by 56.25%, and the gas content is reduced by 37.79%. The permeability coefficient of coal seam increased by 57.29 times, Compared with ordinary boreholes, the average net gas drainage flow of a single hole is increased by 17.50~43.75 times, and the volume percentage of gas drainage is increased by 1.78~2.83 times, which provides key technical support for the gas control of "Three- Soft" coal seams.
- 1
Vulnerability assessment of geological geohazard based on weighted information volume and GIS: A case study of YusheAbstract:
Yushe County is located in the Western foot of Taihang Mountain and has developed geological geohazard such as collapse, landslide and debris flow. Based on GIS and weighted information quantity evaluation model, according to the development characteristics of geological geohazard in the study area, five influencing factors such as slope, slope height, distance from fault, engineering geological petrofabric, distance from road and residential area are selected as evaluation indexes by cluster analysis method, and the susceptibility of geological geohazard in Yushe County is evaluated by weighted information quantity method. The results show that the susceptibility of geological geohazard in the study area can be divided into four levels: extremely high, high, medium and low. The extremely high susceptibility area is mainly distributed in the river valleys of Zhuozhang River and its main tributaries and the hilly areas on both sides, with an area of about 138.28km2, accounting for 8.18% of the area of the whole area; High risk areas are mainly distributed in low mountain and hilly areas, with an area of about 427.15km2, accounting for 25.27% of the area of the whole region; Medium prone areas are mainly distributed in low mountain and hilly areas, with an area of about 628.22km2, accounting for 37.16% of the area of the whole region; Low risk areas are mainly distributed in the low and medium mountain areas of bedrock in Yushe County, with an area of about 497.00km2, accounting for 29.40% of the area of the whole region. The ROC curve is used to verify the evaluation model of geological hazard susceptibility. The AUC value is 0.795 and the evaluation accuracy is good. Through the evaluation method of geological geohazard susceptibility combined with weighted information method and GIS, it provides a scientific basis for geological geohazard prevention and control and land spatial planning in Yushe County.
- 1
Application of Conditional Simulation in Orebody Grade EstimationAbstract:
Conditional simulation is an important part of geostatistical method and a new method developed rapidly after Kriging. Aiming at the problem that the traditional reserve calculation methods cannot fully utilize the original drill hole data and reproduce the spatial variable data distribution, which makes it difficult to accurately guide the subsequent production, this paper proposes an orebody reserve estimation method based on Sequential Gaussian Simulation. On this basis, an underground gold mine in China is used as an engineering example for application research, and the differences and applicability of Kriging interpolation and conditional simulation methods in constructing orebody resource model are compared and analyzed. Among them, a set of equal probability orebody realizations obtained by conditional simulation can better reproduce the spatial distribution pattern and volatility of geological variables, which provide richer geological information for uncertainty evaluation and risk analysis of orebody property indicators.
- 1
Comprehensive Detection and Digital Modeling of Complex Hidden Goaf Group under Abandoned Open PitsAbstract:
The tailings backfill open pits can achieve the dual purpose of geological disaster management and comprehensive utilization of tailings. However, the hidden goaf group under the abandoned open pit has a great impact on the safety and stability of the isolation pillar. critical. Taking the Daye Dahongshan Mine as an example, this paper introduces the application of the comprehensive geophysical prospecting method of the equivalent diamagnetic flux transient electromagnetic method and the fretting seismic method. Combined with the on-site investigation results of the goaf, it is comprehensively deduced that the hidden goaf is delineated 20 and these were verified by drilling. GoCAD software was used to build a digital model of the comprehensive geological body of the surface of the open pit and the goaf, showing the spatial occurrence characteristics of the goaf group, and the volume of the goaf was calculated. These work provide the basic support for the management of potential safety hazards in the area group and the stability analysis of the isolated pillar.
- 1
Preparation of Similar Materials for Transparent Rock Mass and Analysis of Its Physical and Mechanical PropertiesAbstract:
In view of the "black box" problem that it is difficult to observe the deformation and fracture of the rock mass directly, the use of transparent rock mass to conduct similar simulation tests has become a hot issue. The development and preparation of transparent rock mass similar materials is the basis of this research work. E-44 type epoxy resin was selected as aggregate, triethanolamine was used as curing agent, and rosin saturated solution (RSS) was added to adjust brittleness, and a preparation method of transparent rock mass samples was proposed. An orthogonal experiment with 2 factors and 4 levels was designed. The ratio of E-44 epoxy resin and triethanolamine and the content of RSS in the mixed solution were the 2 factors. Then the transparency, rock-like properties and strength adjustability of transparent rock mass under different ratios were studied. The results show that, All of the transparent rock masses prepared with different ratios are transparent. The uniaxial compressive strength, stress-strain curve shape and failure mode of transparent rock samples prepared with different ratios are similar to actual rock, indicating that the transparent rock samples prepared with different ratios have rock-like properties. The uniaxial compressive strength, peak strain and elastic modulus of the transparent rock sample will change greatly with the change of the ratio of E-44 epoxy resin and curing agent and the content of RSS, so it can be adjusted by changing the ratio of raw materials. The transparent rock mass samples prepared meets the strength adjustability. The research results provide a reference for the research and application of transparent rock mass simulation of various original rocks.
- 1
Study on geometrical characteristics and seepage of different rough crack surfacesAbstract:
The fracture structure of natural rock mass is complex and its permeability is much higher than that of matrix rock mass.??In order to study the morphological characteristics of fractures and their influence on seepage characteristics, a four-mesh high-precision 3D scanner was used to measure the THREE-DIMENSIONAL morphology of rock fractures after splitting failure. The Geomagic Studio software was used to select datum for point cloud processing. The surface topography parameters of fractures were obtained based on geographic information technology (GIS) and imported into Comsol numerical analysis software.?The influence of crack roughness on head variation, velocity and hydraulic conductivity under constant head is analyzed.The results show that :(1) With the increase of the roughness coefficient JRC, the frequency distribution histogram of the roughness height of the fracture surface gradually changes from standard type to steep wall type, partial peak type and sawtooth type. The slope direction distribution tends to be concentrated, and the average slope gradually increases.?(2) The fluid flows around the crack, and the velocity of the area with different roughness is significantly different, and the water head decreases slowly in the area with large roughness.?(3) The relationship between flow rate and hydraulic conductivity (Ks) and JRC is an exponential function. The hydraulic conductivity decreases with the increase of crack surface roughness, and the decreasing trend gradually slows down when JRC is greater than 10.
- 1
Study on Mix Design Optimization of Dry-powder Activated Coal Gangue Based Geopolymer ConcreteAbstract:
Aiming at environmental pollution problems of coal waste such as coal gangue, considering the disadvantages of traditional sodium hydroxide liquid activator, such as inconvenient transportation and strong corrosion, this paper adopts alkaline dry powder activator to prepare dry powder excited coal gangue base polymer concrete with coal waste such as coal gangue and fly ash as raw materials. Based on the intelligent algorithm of gravity search algorithm, the modified formula of gravity search algorithm is derived by using chaotic mapping, and the optimal mix ratio of dry powder excited coal gangue base polymer concrete is studied. Under the premise of ensuring strength and workability, and aiming at minimizing economic cost, the optimal mix ratio of coal gangue based geopolymer concrete with different strength grades was obtained. The results show that the economic cost of GSA optimization based on chaotic Chebyshev mapping and Logistic mapping is reduced significantly, and the economic cost of GSA optimization based on different strength grades is saved about 17.74% and 11.65%, respectively. And within a certain range of strength grade, the higher the strength grade, the more cost savings after optimization. For the lowest economic cost of C35 gangue base polymer concrete, the optimal mix ratio is: fly ash: cement: coal gangue: sand: stone = 1:1.1:1.5:3:3.56.
- 1
Analysis on Variation of Infiltration Line and Deformation of Dam Body of Tailings Pond under Rainfall ConditionAbstract:
In order to study the variation law of the wetted line and the deformation of the dam body under the condition of rainfall, the model rainfall test of the tailings pond was carried out in the laboratory. The wetted line changes during rainfall were measured by means of a pressure tube, and the displacement changes of the dam body were obtained by Digital Image Correlation (DIC). The results show that the variation of the displacement near the slope is basically consistent with the variation of the wetting line with time. The variation is rapid in the early rainfall period, and basically does not change after reaching the peak value. The variation trend of the infiltration line of the three kinds of tailing ponds is the same, but with the increase slope ratio, the saturation line is higher and the displacement change is larger. It show that the high infiltration line is more likely to cause the instability of the dam body. With the progress of rainfall, the apparent displacement of tailings pond changes from uniform to non-uniform change. The displacement change below the wetted line is small, but the displacement change above the wetted line is obvious, and the displacement change near the slope is the largest.
- 1
Study on creep parameter analysis and life prediction of tunnel surrounding rock under triaxial compressionAbstract:
In order to study the creep mechanical properties of surrounding rock under different confining pressures, the uniaxial compression creep tests of sandstone and triaxial compression creep tests with confining pressures of 2MPa, 4MPa, 6MPa and 8MPa were carried out. A viscoplastic damage element with long-term strength and time thresholds was introduced, and a 3D creep model was constructed in series with the Burgers model. The evolution law of rock creep parameters under different confining pressures was analyzed, and a creep life prediction method was proposed. The results showed that long-term strength of sandstone under creep is about 72% of the peak strength. The established 3D creep model can accurately describe the whole process of sandstone triaxial creep under different confining pressures. The model parameter analysis shows that: the greater the confining pressure, the more obvious the rock hardening phenomenon, and the less time it takes for the rock to transition to the stable deformation stage; with the increase of the axial stress, the stable creep rate increases in a nonlinear exponential relationship, but the confining pressure increases. Under the action of hoop restraint, the creep rate decreases to some extent; with the increase of confining pressure, the accelerated creep duration increases, and the accelerated creep of rock appears brittle-ductile transformation. A creep life prediction method is proposed based on the strain threshold and the evolution characteristics of damage variables entering accelerated creep, and the prediction results have high accuracy.
- 1
Numerical simulation research on mixing process of filling slurry in rigid-flexible stirred tankAbstract:
Abstract: This paper is based on the fact that the traditional vertical mixing drum has problems such as poor material dispersion, difficult stable and reliable transportation, and uneven strength of the backfill after hardening when the mine uses filter-pressed tailings as the backfill aggregate. Design and develop a rigid-flexible blade combined mixer, conduct research and analysis through FLUENT numerical simulation software and industrial tests. The research results show that, compared with rigid blades, flexible blades have better mixing performance, and both mixing uniformity and mixing speed have certain advantages. And it was successfully applied in an iron ore mine in Shandong, achieving a 10% increase in the mass concentration of the filling slurry and a saving of 10.14 yuan/m3 in the filling operation cost, which solved the problem of frequent pipe blockage accidents caused by the uneven preparation of the filling slurry.
- 1
Optimization of Key Parameters of the Medium Thick Coal Seams Hard and Hard Compound Top Board Cutting along the Air AlleyfAbstract:
The geological conditions of soft and hard composite roof in medium thick coal seam are complex. After cutting the roof and retaining roadway, it is very easy to have problems such as layered collapse of goaf roof, severe disturbance of secondary collapse and serious deformation of retaining roadway. In order to solve this problem, taking 1706 working face of Xinyi Coal Mine as the engineering background, it is planned to carry out a systematic study on the selection of key parameters of roof cutting and roadway retention. Starting from the coal seam thickness and roof distribution, the parameters affecting the effect of roof cutting and roadway retention are mainly roof cutting height and blast hole plugging; Based on the principle of self bearing characteristics of rock fragmentation and expansion, the cutting height is preliminarily designed, and then the fracture mechanics model of rock beam with crack composite roof is established to theoretically analyze the relationship between cutting height and fracture of composite roof; Based on the mechanism of blast hole plugging and blasting rock breaking, the idea of segmented plugging is proposed for the soft and hard composite roof rock, and the calculation method of plugging length of soft rock section and hard rock section is deduced. The field test and monitoring data show that when the key parameters of roof cutting are 8.5m height of roof cutting, 0.5m plugging of hard rock section and 1.5m plugging of soft rock section, the cracks in the hole are continuous and the crack rate reaches 92%; After roof cutting, the stress of the anchor cable is stable at 172kN, and the final separation of the roof is 35mm, which is reduced by 23% and 55% respectively compared with the non roof cutting section. The composite roof collapses smoothly at one time, and the roadway retaining effect is good, which provides a certain reference for the selection of key parameters of roof cutting and pressure relief roadway retaining along the goaf under similar geological conditions.
- 1
Numerical Simulation of Reasonable Position Layout of Lower Coal Mining Roadway in Short Distance Thin Coal SeamAbstract:
Aiming at the problem that the upper mining of short-range thin coal seam has a significant impact on the layout of mining roadway in lower coal seam, this paper takes 3211 and 3231 working faces of Zhouyuanshan mining branch as the research background. this paper theoretically calculates and analyzes that the action range of the lateral support stress formed by the mining of the upper coal seam on the lower coal seam is 34.9m. Combined with FLAC3D numerical software, the plastic failure characteristics of the roadway under different external staggered layout are simulated and analyzed The results show that the roadway roof with an external offset of 0-30m is mainly plastic deformation, and the roadway can be ensured to be in the original rock stress area only when the external offset is more than 40m. The range of plastic areas on both sides of the roadway is reduced, and the roof has almost no plastic damage, which is conducive to the support of the roadway. Based on the results of theoretical calculation and numerical simulation analysis, it is obtained that the reasonable layout position of roadway in lower coal seam should be more than 40m. The research results can provide reference for similar roadway stability control.
- 1
Research on Intelligent Image Recognition of Coal Slime Moisture Experiment and Mathematical ModelAbstract:
Aiming at the problem of the lack of efficient online moisture detection of the coal slime in the actual production of the coal processing plant, a moisture detection experiment based on flotation concentrate images is carried out by intelligent image recognition technology, the relationship between image features and moisture is investigated, and a mathematical model of flotation concentrate moisture and feature values is established based on multiple polynomial regression analysis, and the final optimal moisture prediction mathematical model is obtained based on the stepwise regression algorithm. The results show that: there is a positive correlation between the moisture content of coal slime and the brightness of the surface of coal slime; there is a more obvious monotonic relation-ship between moisture and eigenvalues in a specific interval; using the image grey-scale eigenvalues as the input variables of the model, the moisture prediction of coal slime images under green light source is the best, and the moisture prediction values show a monotonic increasing trend to achieve the most ideal prediction effect. The root mean square error RMSE is 0.12 and the coefficient of determination is 0.9998. This intelligent image recognition method provides a new idea for online detection of flotation concentrate coal moisture, enhance eco-nomic efficiency and achieve intelligent development of flotation process.
- 1
MECHANICAL PROPERTIES AND OF ROCK UNDER DIFFERENT WATER BEARING CONDITIONS STUDY ON STRESS-STRAIN RELATIONSHIPAbstract:
The triaxial test of Ogino tuff with different water content is carried out, and the change patterns of rock stress-strain curve at each stage and the peak stress, strain and elastic modulus of rock are analyzed. The conclusions are as follows: (1) The peak stress, strain and elastic modulus decrease linearly with the increase of relative water content; (2) At the initial stage of loading, the stress-strain curve is concave due to crack closure, then increases approximately linearly, and then deviates from linearity to convex. The peak stress can be well fitted by cubic polynomial; After the peak strength, whether the stress of the specimen decreases rapidly in the dry state and the curve is concave, or the stress decreases slowly in the water state and presents plastic flow, it can be well fitted by fractional function; (3) According to the piecewise fitting function provided, combined with the linear relationship between relative water content and peak stress and strain, the rock stress-strain curves under different water content can be obtained approximately.
- 1
Research and Analysis of Electromagnetic Compatibility Conducted Interference Test of Mine Frequency ConvertersAbstract:
Abstract: Electrical intelligent equipment can improve mining efficiency and is widely cited in mining. With the influx of more and more electronic equipment into the mine, coupled with the inherently harsh mining environment of the mine, the electromagnetic interference faced by the electronic equipment in the mine has become more and more severe. Compatibility performance, this paper builds an experimental platform for electromagnetic compatibility conducted interference testing, conducts conducted interference experimental tests on mining inverters, and studies the disturbance characteristics and distribution rules of conducted interference generated by mining inverters. The results can be used as a test for handling conducted interference The reference of the practitioners is of guiding significance for the electromagnetic compatibility test and rectification of mining frequency converters.
- 1
Study on high-efficiency and low loss & dilution mining of branch orebody in Longshou MineAbstract:
It is very important to formulate appropriate ore mining and recovery scheme for realizing efficient and low loss and dilution in underground metal mines. Based on the determination of the mining scheme of the branch ore body in the sublevel caving stope of the West No. 2 mining area of Longshou Mine as the engineering background, the mining scheme of arranging the mining drift along the strike of the hanging wall branch ore body + arranging the mining drift along the vertical strike of the footwall branch ore body and the mining scheme of arranging the mining drift along the overall vertical strike are preliminarily determined. Based on the comprehensive consideration of the layout of mining preparation works, ore loss and dilution control, production organization and management, mining operation safety and stope ventilation, it is analyzed and studied that the mining scheme with overall vertical mining drift has more advantages. At the same time, combined with the occurrence conditions of the branch ore body, the ore recovery scheme is set for each section for the only three mining sublevels in the stope, and finally a three section combined ore recovery scheme is formed, which provides theoretical basis and technical guidance for branch orebody mining.
- 1
Evaluation of Rock Burst Intensity Based on Game Grey Target ModelAbstract:
Rock burst has always been a difficult problem faced by deep high stress underground engineering. In order to effectively predict and evaluate the rock burst disaster of underground rock mass engineering, a rock burst intensity grade evaluation model based on game theory combined weighting and grey target decision-making is established . Firstly, the quantitative indexes such as the ratio of uniaxial compressive strength to tensile strength σc /σt, the ratio of tangential stress to uniaxial compressive strength σθ/σc, the elastic deformation energy index Wet and the integrity coefficient Kv are selected to establish the evaluation index system. By applying Critic , coefficient of variation and entropy weight method, the weight of each indicator is calculated. Then, combined with the grey target decision theory, the comprehensive target distance distribution set of different rock burst intensity levels is founded. Finally, the rock burst intensity grade is judged by integrating the size of bull 's-eye distance. In order to verify the accuracy and rationality of the model better, takes the rock burst of Zhongnanshan highway tunnel project as example and analyzes the evaluation model according to the measured data. The upshot of this example shows that the rock burst evaluation results based on the game gray target model are basically accordant with the actual?state, and the rock burst intensity evaluation model has good accuracy and reliability.
- 1
Timing Characteristics of Sandstone Damage under the Action of Low Velocity Water FlowAbstract:
To investigate the damage aging characteristics of sandstone under the action of flowing acidic solution, the microstructure changes and macromechanical property deterioration of the specimens were analyzed by scanning electron microscope and MTS-815 rock mechanics test system, and the mass and dimensional changes of the specimens were measured at different time nodes. The test results show that: (1) the lower the pH value and faster the flow rate of acidic solution at the same time, the larger the changes of porosity, mass and diameter dimensions of the specimens. And in each environment, the degree of change was the greatest at the beginning and gradually stabilized at the later stage. (2) The microstructural damage on the surface of sandstone is negatively correlated with the solution pH and positively correlated with the flow rate, the lower the solution pH is. It shows an increase in the number of secondary pores, well-developed microfractures and a rise in the sparseness of the structural framework. (3) Compared with the dry state, the peak partial stress intensity of the specimens immersed by the solution with pH=3 decreased by 32.85%, 36.47% and 39.14% under the circumferential pressure of 5MPa, 10MPa and 15MPa, respectively; while the peak intensity decreased cumulatively by 32.85%, 44.77% and 42.56% under the simulated flow rate v=500mm/s and pH=3 solution environment, respectively and gradually leveled off with time. In addition, the cohesion and internal friction angle also decayed with time, and the cohesion was more sensitive to the acidic solution. (4) The strength model established by the change law of corrosion depth of the integrated specimen in the flowing acidic solution environment is in good agreement with the test results.
- 1
Study on Evolution of Void Structure and Seepage Characteristics of Crushed Coal Under PressureAbstract:
In order to explore the evolution law of internal void structure and gas seepage characteristics during the compression process of crushed coal and rock mass, a compaction-CT scanning device for crushed coal and rock mass was independently developed. Taking 5-10 mm crushed anthracite as an example, the void network model of crushed anthracite under three stresses was established by CT scanning, image processing and three-dimensional reconstruction. On this basis, numerical simulation research was carried out. The research results show that: (1) Stress has a significant effect on the void size and connectivity of crushed anthracite under pressure. The void volume, pore throat cross-sectional area and average coordination number show a decreasing trend with the increase of stress, and the connectivity of void space also decreases. (2) Both the porosity and absolute permeability of crushed anthracite decrease with the increase of stress, and the absolute permeability decreases by one order of magnitude when the stress increases from 0 MPa to 23.24 MPa. (3) Due to the difference of the void structure, the gas flow in the crushed anthracite coal has a high flow rate area and a low flow rate area, and the high flow rate area mostly exists in the area where the seepage channel changes from large to small. The research results can provide a theoretical reference for the efficient extraction of coalbed methane in crushed coal and rock mass.
- 1
Study on Integral Instability Impact Mechanism of Isolated Island Coal Pillar in Fully Mechanized Top Coal Caving Face With Deep TopsoilAbstract:
Taking 7303 working face of Zhaolou coal mine as the background, the overall instability impact mechanism of isolated island coal pillar in fully mechanized top coal caving stope with deep topsoil is studied by using the methods of theoretical analysis and numerical simulation. The following research results are obtained: the evolution law of overburden spatial structure of isolated island coal pillar in deep topsoil fully mechanized top coal caving stope is found, and the estimation model of bearing pressure before and after bedrock fracture in deep topsoil fully mechanized top coal caving stope is established. Through calculation, the critical width of isolated island coal pillar in 7303 goaf of Zhaolou coal mine based on erosion prevention is 99m, which is verified by numerical simulation. Before the fracture of the bearing bedrock in the fully mechanized top coal caving face with deep topsoil, with the advance of the working face, the peak value of the stope bearing pressure increases and the peak position is far away from the coal wall. After the fracture of the bearing bedrock, due to the loading effect of the earth pressure arch, the peak value of the stope bearing pressure moves forward and increases rapidly and the total influence distance decreases. The overall instability type impact mechanism of the isolated coal pillar in the fully mechanized top coal caving face with deep topsoil is as follows: after the bedrock bearing the topsoil in the adjacent goaf of the isolated coal pillar is broken, the thick topsoil cannot transfer stress as an independent rock stratum, the transmission load range of the formed earth pressure arch is reduced and the stress is highly concentrated, resulting in the superposition stress on the coal pillar exceeding its bearing limit, resulting in the overall instability type rock burst.
- 1
Optimization of wet screening process parameters on electromagnetic linear vibrating screenAbstract:
Aiming at the problems of low efficiency, poor quality of under-sieves, and unclear screening mechanism in wet screening process, an experiment was carried out to explore the mechanism of wet screening process parameters of electromagnetic linear vibrating screen with the goal of screening efficiency. The Central Composite designs was used to conduct a five-level response surface experiment with four factors (vibration frequency, amplitude, inclination angle of screen surface and material solid-liquid ratio). According to the experimental results, the independent effect analysis of each screening process parameter is carried out, and the mathematical model of sieving efficiency was established by multiple linear regression method, and the model was tested. The research results show that lower amplitude and vibration frequency can bring higher screening efficiency. The screening efficiency increases with the increase of the inclination angle of the screen surface and decreases with the increase of the solid-liquid ratio. This research can provide a reference for the structural optimization design and process parameter optimization of electromagnetic linear vibrating screen.
- 1
Mining Technology And Dam Stability Analysis Of A Tailing PondAbstract:
Mining industry plays an important role in assisting the realization of the national goal of "carbon neutrality and carbon peak", which is mainly reflected in the comprehensive utilization of bulk solid waste, especially the comprehensive utilization of tailings, which has great economic and environmental significance. Taking the mining project of Jingcheng Tailings Reservoir in Cenxi City as the engineering background, the combined mining method of water gun and floating sand pump ship was adopted. The slide slope simulation software was used to analyze the stability and safety of the internal and external slopes of the tailings dam under three different working conditions by using the Ordinary or Fellenius method, including the status of the tailings reservoir, the tailings recovery to +317m elevation and the completion of the tailings recovery. According to the calculation, the Kmin values of the internal and external slopes of the tailings dam body are greater than the standard values under different working conditions, and the tailings dam body can maintain stable operation during the whole mining process. Aiming at the possible safety problems during tailings recovery, corresponding mine production management measures are put forward, which has certain reference value for tailings reservoir mining projects of the same type.
- 1
Study on Reasonable Size of Waterproof Coal Pillar in Fully Mechanized Caving Face of a Coal Mine in ShanxiAbstract:
In order to study the width of the coal pillar in the upper adjacent goaf with abundant water, taking the 2206 and 2207 working faces in the second mining area of a coal mine in Shanxi as the engineering background, field and laboratory tests, theoretical analysis and numerical simulation were used to study the size of the coal pillar in the upper adjacent goaf. Using drilling into coal and rock mechanics test for rock fracture and strength characteristics, and based on the elastic-plastic theory and plastic coal pillar width calculation formula was deduced and constraint theory, on this basis, using the numerical simulation study of coal pillar abutment pressure distribution law and different width coal pillars in the upper and lower section stress and plastic deformation during mining face. The results show that :(1) the internal integrity of coal pillar is good, the self-stability of coal rock is strong, and the theoretical calculation value of the minimum reserved width of coal pillar is 15.8m; (2) The peak value and concentration coefficient of vertical stress in coal pillar decrease gradually with the increase of width during mining of upper section 2207 working face, and the connectivity deformation failure will occur in coal pillar below 25 m. (3) After mining at the 2206 working face in the lower section, the distribution of vertical stress in coal pillar with width of 25 m and above presents a "double peak and valley" type, with elastic core area and plastic failure failure. Based on the test and numerical simulation results, the reasonable width of water-proof coal pillar is determined to be 25 m, considering the factors of mine safety and stability and efficient mining. The conclusion can be used as a reference for the work of coal pillar setting in mines with similar working conditions.
- 1
Influence of Metal Ions in Wastewater on Zinc Oxide FlotationAbstract:
Aiming at the problem that lead-zinc mineral processing wastewater has an adverse effect on zinc oxide flotation, the main reasons why the wastewater affects the zinc oxide flotation are studied, and the mechanism of the influence of the mineral processing wastewater on the zinc oxide flotation is revealed. The effects of pH value and concentration of various metal ions on zinc oxide flotation in lead-zinc mineral processing wastewater were investigated. The results show that calcium ions have a greater impact on zinc oxide, mainly because they affect the adsorption of collectors on the mineral surface. Sodium carbonate can eliminate the influence of calcium ions in wastewater and improve zinc oxide flotation. The research provides a reference for wastewater reuse and improving the utilization rate of zinc oxide resources.
- 1
PHREEQC simulation of uranium species in groundwater of decommissioned mining area of in-situ leaching uranium mineAbstract:
In this paper, the groundwater in the decommissioned mining area of an in-situ leaching uranium mine in Northwest China is selected as the research object. Through field investigation and sampling analysis, the content of uranium and other physical and chemical properties in groundwater are studied. The geochemical model PHREEQC is used to calculate the given form of uranium in the water environment of this area, and the influence of uranium form under different pH, temperature, SO42- concentration and NO3- concentration is simulated by changing the simulation conditions. The results show that the valence state of uranium in groundwater in this area is nearly 100% U(Ⅵ), and its forms mainly exist in the forms of UO2SO4, UO22+, UO2(SO4)22- and UO2NO3+, accounting for 72.0%, 20.7%, 7.2% and 0.1% respectively. The simulation results show that when pH=2~5, UO2SO4 has always been the dominant species state in the water environment. With the continuous increase of pH value, UO2(OH)2 increases significantly and becomes the dominant species state after pH=5; When the temperature is in the range of 10~40℃, UO2SO4 is always the dominant species in the water environment. With the increase of temperature, the content of UO2SO4 also increases slowly; With the decrease of SO42- concentration, UO2SO4 will decrease. When the SO42- concentration is as low as 0.005 mol/L, UO22+ becomes the dominant species; With the decrease of NO3- concentration, UO2NO3+ will decrease slowly, but the dominant species state is still UO2SO4.
- 1
Model Test Study on Composite Retaining Structure of Micro-pile Frame BeamAbstract:
At present, there are few and immature researches on the combined retaining structure of anti-sliding micro-pile and connected beam, and there are some leading theoretical researches in engineering practice. In order to explore the sliding resistance effect and stress failure law of the multi-row oblique connected micro-pile frame composite structure laid on the slope surface, this paper adopts the method of similar model test and draws the following conclusions: When the settlement displacement of the model slope top reaches 200mm, the load on the top of the slope is 7.5T, 26.5t and 36.5t respectively under three working conditions. The micro-pile frame beam structure with multiple rows of oblique connections can effectively improve the bearing capacity of the slope, and reducing the pile spacing can also improve the bearing capacity of the slope. From the top of the slope to the foot of the slope, the failure modes of each row of micro-piles are different, and the bending failure of the sliding section weakens successively. The upper part of the pile is positive bending moment, the lower part is negative bending moment. The dividing point of positive and negative bending moment is located at a certain position above the sliding surface, and the maximum point of bending moment is 2~3 times the pile diameter below the sliding surface. The soil resistance of micro-piles near the top and foot of slopes is relatively large, so the bending resistance of these micro-piles should be paid more attention to in engineering design. The experimental results have reference significance for understanding the supporting effect and failure mode of multi-row inclined micro-pile frame beam structure.
- 1
Flotation Concentrate Grade Detection Based on SA-VAEGANAbstract:
In allusion to these issues that concentrate grade modeling of froth image processing exists involving shortage of effective froth image samples, low accuracy in model detection, poor generalization ability and robustness in the process of mineral flotation, it is proposed that the model of generative adversarial network based on self-attention mechanism and variational autoencoder. Among them, the generator employs the variational autoencoder consisting of an encoder and decoder. And the coding layer introduces the self-attention mechanism, making the convolution operation can better capture the long-distance dependence to acquire the overall information and generate high-quality images. The checker embedded in the classifier not only has the function of discriminating true from false, but also accomplishes the goal of inspection. Experimental results indicate that the model has quite strong generalization ability and robustness, and effectively increases the accuracy of froth image identification.
- 1
Research on the Control Method of Roadway Sub-sections Bottom Drum under the Disturbance of Close Coal Seam MiningAbstract:
Aiming at the problem of tunnel bottom drum of the underlying coal seam in the process of short-distance mining, this paper uses the method of combining numerical simulation and field monitoring to study the control method of the tunnel bottom drum of the close- distance coal seam in a mine. The results show that as the working face of the overlying coal seam advances, the stress on the roadway of the underlying coal seam first increases and then decreases, and the stress peak appears at the position 15m from the working face to the roadway, where the maximum vertical stress of the roadway is 28.5MPa, and the displacement of the roof and floor and the two sides are 195mm, 773mm and 135mm respectively, and the deformation of the roadway floor is the most serious. Based on this research, a sub-section floor drum control method is proposed, which combines the pressure relief of roadway floor cutting grooves and the strengthening support of "U-shaped steel + reverse bottom arch", and the reasonable pressure relief groove parameters are given.. Through field practice, the maximum vertical displacement of the floor in the grooved pressure relief section and the reinforcement support section of the roadway floor was reduced by 62.1% and 58.1%, respectively, realizing the effective control of the bottom heave of the coal seam roadway.
- 1
Preparation of Crosslinked Cationic Starch Flocculant and its Flocculation Performance of Coal-slime WaterAbstract:
In order to treat coal slime-water, the crosslinked cationic starch flocculant was prepared in this paper. The prepared samples were characterized and analyzed by Scanning Electron Microscope (SEM), X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FT-IR), and the effect of various factors on the flocculation performance of coal slime-water was investigated using coal slime-water as the test object. The results showed that the methacryloyloxyethyl trimethyl ammonium chloride (DMC) and 2,3-epoxypropyl trimethyl ammonium chloride (GTA) were successfully synthesized on the starch backbone and the cationic starch was crosslinked successfully. Compared cross-linked cationic starch and commercially available anionic (cationic) polyacrylamide, the results showed that the cross-linked cationic starch has low turbidity, wide pH range, high floc compression rate and low cake moisture content when treating coal slime-water. The EDLVO theory was used to analyze the excellent flocculation performance of cross-linked cationic starch flocculants on coal slime-water.
- 1
Practice of high efficiency flotation transformation in a gold mine concentratorAbstract:
a gold mine concentrator has carried out a series of high-efficiency transformation for flotation operation, focusing on strengthening the recovery effect of coarse-grained minerals. At the same time, according to the optimization idea of "can collect and early collect", two concentrate output points are added in the middle link of flotation, which reduces the loss probability of useful minerals in flotation cycle. After the transformation and operation, the flotation recovery rate of the gold mine has increased by 1.34%, the annual gold output has increased by 52.86 kg, and the economic benefit has increased by 19.5574 million yuan.
- 1
Molecular Dynamics Simulation of Hydration and Swelling Mechanism in the Interlayer of Mixed-layer ClaysAbstract:
More than 70 percent of all clays on the Earth's surface are of mixed-layer types, and knowing their swelling behavior is crucial to reducing soil expansion and mining development. Through the water-insert and interaction energy scripts, a molecular dynamics (MD) study of the differences in swelling behavior between the most important illite-montmorillonite (I-M) mixed-layer clays (MLCs) and Na-montmorillonite (MMT) is conducted. It captures the evolution of quantitative properties such as basal spacing d and interaction energy in the clay interlayer, increasing hydration for the first time. It is found that MLCs have smaller swellings than Na-MMT due to the asymmetric interlayer and mixed counterions. The clay-clay and clay-ion interaction energy drop, while the clay-water interaction energy increases with increasing hydration. In addition, the attractive interaction of clay-bound water seriously promotes swelling, of which the Coulomb interaction plays the most dominant role. The higher the K+ concentration, the more pronounced these phenomena are. This work provides insight into the molecular mechanism for initial swelling and clay-bound water interaction in MLCs. This will help to decipher its specific role in soils and minimize clay swelling in geohazards.
- 1
Enrichment of Bacterial Communities Capable of Reducing Nitrate and Their Role in Removal of Nitrate from Groundwater at Acid in Situ Leach Uranium MineAbstract:
In order to remove nitrate from groundwater at acid in-situ leach uranium mine，nitrate reducing bacteria communities were enriched from soil or rock samples in different areas by enrichment reaction system, and their reduction effect on nitrate in the groundwater was investigated. The results showed that three groups of bacteria communities with nitrate reduction capability were enriched, but only the group of bacteria enriched from the core sample at a decommissioned acid in situ leach uranium mine in Northwest China could adapt to its acidic uranium contaminated groundwater environment and had good capability of nitrate reduction. In?the?meantime，this community could reduce the nitrate concentration in the groundwater from 100 mg/L to 1 mg/L within 10 d, pH increased from 3.0 to 5.0 approximately，and its dominant bacteria were Tumebacillus, which accounts for 31.62%.
- 1
Characteristics and Influencing Factors of Shear Strength Index of Ionic Rare Earth OreAbstract:
The in-situ leaching process is usually used to exploit ionic-absorbed rare earth mine, which makes the shear strength of mines reduce, resulting in slope instability. Therefore, laboratory test was employed in this research in order to study the change rule of shear strength indices of ore body on condition that initial dry density, initial water content and pore solution type were considered. The results indicated that when the initial water content was constant, the cohesion of ionic-absorbed rare earth mine was positively correlated with the initial dry density, and its internal friction angle changed little with the initial dry density. When the initial dry density was constant, the cohesion of ionic-absorbed rare earth mine was negatively related with the initial water content, and its internal friction angle increases slightly with the increase of the initial water content. Under the influence of different initial dry density and water content, a linear relationship between Ccu and C' was good. When the initial dry density and water content were constant, the relationship between C and φ values of CU test, UU test and quick direct shear test was: Cq > Cuu > Ccu and φcu ≈ φq. When (NH4)2SO4 solution, MgSO4 solution and equal proportion mixed solution of (NH4)2SO4 and MgSO4 were used respectively as pore solution, the relationship among Cuu values of ore body: MgSO4 > (NH4)2SO4 > mixtures. In addition, the Cuu and Cq values of the ore body were almost the same when MgSO4 was used as pore solution, the Cuu and Cq values of the ore body are close to the same. The research results could provide a theoretical guidance for the stability evaluation of mine slope in the mining process of no ammonia nitrogen or less ammonia nitrogen.
- 1
Research on Mergers and Acquisitions Valuation of Mining Projects Based on DCF Method and Market Method——Taking Lion Project as An ExampleAbstract:
In order to get rid of the dilemma of resource shortage, large domestic mining enterprises began to invest in mineral resources overseas. As a basic tool for investment analysis and decision-making, mining project valuation can help enterprise operators better grasp the prediction and management of the future, ensure the best benefit of mining investment. Based on DCF method and market method, take the lion mine project in Africa as an example for value evaluation. Finally, the evaluation results are compared and verified in combination with the current mining market, so as to judge whether the mergers and acquisitions behavior is correct.The results show that: complete the transaction of the target project at the time point of the base date is a correct decision, the evaluation method combining DCF method and market method is more scientific and reasonable than the traditional evaluation method, it can provide reference for mining investment and mergers and acquisitions decision-making.
- 1
Design and Application of Phosphorus Mine Safety Control System Based on Dual-Prevention MechanismAbstract:
In order to reduce the probability of accidents in the production and operation of phosphate mines and prevent the occurrence of major accidents, the application of the "dual-prevention mechanism" in the safety production management of phosphate mine enterprises shall be implemented by learning from the experience of predecessors in the intelligent construction of mines. Taking J2EE as the development platform, SpringMVC as the development structure, adopting the combination of B/S and C/S mode and combining with WebGIS technology to design an intelligent comprehensive management and control platform that integrates security inspection management, risk classification management and control, and hidden danger investigation and management.The research results show that the cross-platform collaboration between the mobile and PC ends of the system effectively meets the needs of dual-control work in phosphate mines, realizes closed-loop management and dynamic control of risks and hazards, reduces the probability of accidents in phosphate mines, improves the efficiency of personnel work management, and creates a new model of phosphate mine safety management.
- 1
Application of Field Mixed Emulsified Explosive Technology in Jinchuan Long Shou MineAbstract:
In order to solve the problems of low efficiency, low safety, high labor intensity and high blasting cost of jinchuan long shou mine approach, the use of on-site mixed emulsified explosive blasting technology is proposed. Through theoretical calculation and testing, the relevant parameters of mixed emulsified explosives were determined, and the evaluation formula for the rationality of the design of blasting parameters was formulated, and the preliminary calculation and judgment of the parameter design were reasonable. Through on-site tests, comparative analysis shows that: the inlet recovery adopts the on-site mixed emulsified explosive blasting technology, the charging efficiency is increased by 35.5%, the service capacity is increased by 213,000 tons / year, the blasting input is increased by 0.23m / gun, the amount of collapse is doubled, the blasting unit consumption is saved by 258,000 / year, the management of blasting materials and manual operation safety are higher, and the labor intensity is lower.
- 1
Study on the New Collector KP16 in Flotation Test of the Copper-lead Polymetallic Ore in the Western of Yunnan ProvinceAbstract:
Copper and lead play an important role in national development and construction. However, with the gradual consumption of copper-lead easy-to-separate ores, the research on copper-lead refractory ores has become inevitable. This study takes a low-grade copper-lead polymetallic sulfide ore as the research object in western of Yunnan province, adopts the process flow of copper-lead-sulfur missed flotation, copper-lead separation and lead-sulfur separation, applies the new efficient and environmentally collector KP16 in the mixed flotation stage, recovers copper lead and silver at the high extent. The flotation indicators obtained is that the copper grade of the copper concentrate is 24.48%, the lead content is 5.50%, the copper recovery rate is 83.69%, the copper concentrate contains silver 479.6g/t, and the silver recovery rate is 48.44%; The lead recovery rate is 91.29%, the lead concentrate contains 110.7 g/t silver, and the silver recovery rate is 29.14%; the total silver recovery rate in copper concentrate and lead concentrate is 77.58%. It provides a technical basis for the efficient and comprehensive utilization of the ore, and has reference significance for the study of the same type of ore.
- 1
Damage evolution analysis of gas-bearing coal and rock under different loading pathsAbstract:
The damage evolution law of loading gas-bearing coal and rock from yield deformation to instability failure is related to the loading stress path, and has a certain influence on the occurrence of coal and gas outburst. Based on the energy conservation theory, the expression of damage factor in the whole process of gas-bearing coal and rock from loading to instability failure is analyzed and deduced, and the evolution law of damage factor in the whole stress-strain process of gas-bearing coal and rock under conventional triaxial loading and variable-speed piecewise triaxial loading stress path is calculated and analyzed. The results show that under different loading stress paths, in the linear elastic stage, the damage factor of loaded gas-bearing coal and rock is equal to 0, the damage factor begins to increase rapidly in the plastic deformation stage, and the damage factor of coal and rock increases sharply in the stress drop stage. After entering the residual strength stage, the growth rate of damage factor of coal and rock slows down significantly. The increase of gas pressure can promote the damage development of coal and rock, resulting in the overall increase of the critical damage factor at the moment of instability and failure and the damage factor entering residual strength. The increase of confining pressure can inhibit the damage development of coal and rock, resulting in the overall decrease of the critical damage factor at the moment of instability and failure and the damage factor entering residual strength. Compared with conventional triaxial loading, the critical damage factor at the moment of instability and failure of gas-bearing coal and rock and the damage factor when entering the residual strength under variable-speed piecewise triaxial loading condition are larger as a whole, the shear slip surface of coal and rock specimen after failure is more obvious as a whole, the fracture connectivity is better as a whole, the fracture opening is also larger, and the broken coal and rock are easier to separate.
- 1
Preparation of Carboxymethyl Cellulose Modified Zero-valent Iron Nanoparticles and Their PerformanceAbstract:
It is a difficult problem to remediate acidic uranium contaminated groundwater. Nano zero valent iron (nZVI) shows a good application prospect in solving this problem, but it is prone to agglomerate, oxidize and decrease in reaction activity, which restricts its application in the remediation of the uranium contaminated groundwater. In order to solve these problems, CMC-nZVIs with different proportions (0%, 0.1%, 0.5%, 1.0%) of CMC were prepared by modifing nZVI with carboxymethyl cellulose (CMC), and their sedimentation, oxidation resistance, particle size, and uranium removal performance from acidic liquid were investigated. The results showed that with the increase of the proportion of CMC, the particle size of CMC-nZVI became smaller, the dispersion, better and the oxidation resistance, stronger. Among them, CMC-nZVI with 1.0% CMC had the smallest particle size, the best dispersion and the strongest oxidation resistance, and it had no obvious sedimentation and oxidation after 60 days. When the initial uranium concentration of acid wastewater is 5 mg / L and its initial pH, 3, CMC-nZVI with 1% CMC had the best removal performance of U(VI), with the removal rate reaching 97.64%, and the pH level being raised to 5.21. These findings provide a theoretical support for the practical application of CMC-nZVI in the remediation of acidic uranium contaminated groundwater.
- 1
Study on the propagation characteristics of rock stress waves under the action of high water pressure and high stressAbstract:
When blasting excavation of deep high water pressure rock project, the surrounding rock body is subjected to the combined effect of high water pressure, high ground stress and blasting dynamic load. Due to the lack of kinetic test methods and test systems for rocks with high hydraulic pressure and high ground stress, its theoretical research lags far behind engineering practice. In this paper, based on the self-researched test system, stress wave propagation tests are conducted on red sandstone to explore the attenuation law of stress wave propagation in red sandstone under the combined action of high water pressure and high ground stress. The results show that when the impact velocity and axial static stress are certain, the stress wave velocity of red sandstone gradually increases with the increase of water pressure, and the wave velocity changes as a quadratic function with the increase of water pressure. In the fitting function, the quadratic term coefficient, the primary term coefficient and the axial static stress show a linear correlation, and the constant term and the axial static stress show a nonlinear correlation. For the red sandstone with small initial damage, the presence of water pressure causes the fractures inside the rock to be squeezed, which enhances the rock wave impedance and facilitates the propagation of stress waves in the rock specimen.
- 1
Acoustic Emission Characteristics Study of Coal Rock Mass Fracture with Different Coal Thickness Under Supercritical CO2 InteractionAbstract:
Injecting CO2 into deep unminable coal seam is an effective means of CO2 long-term storage. However, CO2 in supercritical state under high temperature and high pressure will greatly degrade the mechanical properties of coal. In order to study the influence of coal thickness on AE(acoustic emission) characteristics of RCR (rock-coal-rock) composite under uniaxial compression before and after supercritical CO2 treatment, The uniaxial compression test and AE monitoring of coal and rock mass were carried out. The results show that :(1) with the increase of coal thickness, the compressive strength, elastic modulus, AE peak count, energy and cumulative energy of the composite decrease, while the cumulative AE count increases, energy builds up over time, the strain and time required during failure increase in different degrees; (2) After soaking in supercritical CO2, the compressive strength, elastic modulus, AE peak count, cumulative count, energy and cumulative energy of the composite decrease significantly, the strain and time required during failure decrease to varying degrees; (3) The combination under the action of supercritical CO2 is more prone to instability and takes shorter time to accumulate energy. With the increase of coal thickness, the instability trend becomes larger, but the energy release gradually moderates. The research results can provide reference for the stability of CO2 geological sequestration.
- 1
Influence of modified iron tailing powder on the properties of medium and high strength concreteAbstract:
In order to study the effect of modified iron tailing powder on the compressive strength、working performance and durability of medium and high strength concrete, the C50 concrete were produced by different amounts of modified iron tailing powder, which completely replacing fly ash as the mineral admixture. The fly ash group with the same amount of iron tailing powder was set as a control group. The results show that the modified iron tailing powder concrete has better working performance, and the 28d compressive strength of modified iron tailing powder concrete decreases with the increase of modified iron tailing powder content. When the amount of tailing powder in total mineral admixture is 30%-60%, it can meet the compressive strength requirements of C50 concrete. When the content of modified iron tailing powder is 40%-60%, the anti-carbonation performance first increases and then weakens with the increase of tailing powder content, which is basically the same as that of the fly ash control group; the anti-permeability performance weakens with the increase of tailing powder content, but the anti-permeability grades can be consistent with the fly ash control group, which is "very low"; the anti-sulfate erosion performance and anti-freezing performance are enhanced with the increase of tailing powder content; the sulfate resistance grade can reach KS180, the antifreeze grade can reach F250, and all are better than the fly ash control group. In general, the modified iron tailing powder can be used in medium and high strength concrete instead of fly ash when the dosage of total mineral admixture is 40%-60% .
- 1
Application and research progress of computational fluid dynamics ( CFD ) in filling slurry transportationAbstract:
Abstract: The pipeline transportation of filling slurry is one of the most important processes in filling mining, which directly affects the efficiency of filling system. It is urgent to explore a new research method for slurry pipeline transportation. Combined with the application of computational fluid dynamics ( CFD ) in pipeline transportation of filling materials, the calculation method and process of CFD technology are introduced. The research status and application difficulties of CFD in filling material flow characteristics, pipeline transportation characteristics and pipe network parameter optimization in recent years are analyzed. It is concluded that there are some problems in the application of computational fluid simulation in paste transportation, such as difficult modeling and meshing of complex pipeline transportation system, unable to study the microscopic mechanism of slurry transportation process, and difficult selection of slurry transportation parameters. Furthermore, the research trend of the application of CFD in slurry transportation in filling mining is discussed, and it is considered that ' improving the calculation accuracy ' and ' industrial application ' will become the main research direction of CFD application in filling field. The analysis shows that CFD technology will have a broad application prospect in the simulation calculation of filling material pipeline transportation.
- 1
Mechanical Properties and Parametric Damage Characteristics of Sandstone under the Action of Low Velocity Water FlowAbstract:
A series of uniaxial and triaxial compression tests were conducted to compare the strength and deformation characteristics of sandstone and the response mechanism of relevant parameters under the action of water-chemical solution based on the natural dry state and the corrosive effect of water-chemical solution with different flow rates and different pH values. The test results found that the uniaxial and triaxial compressive strengths, characteristic stresses at each stage, elastic modulus, cohesion and internal friction angle of sandstone decreased with decreasing solution pH and increasing water flow rate. However, Poisson"s ratio increased with decreasing solution pH and increasing water flow rate. In terms of microstructure, the porosity gradually increases with decreasing solution pH and increasing water flow rate, and the original dense pore structure gradually develops into irregular honeycomb structure, which leads to macroscopic deformation and strength characteristics of sandstone gradually deteriorate.
- 1
Experimental study on acoustic emission characteristics of artificial sandstone under uniaxial compressionAbstract:
The crystal particle size and its cement are important factors affecting the mechanical properties and behaviors of rocks. Due to the strong randomness of the crystal particle size and cement content in natural rocks, three artificial sandstones with different particle sizes and three different cement contents were prepared, and the effects of crystal particle size and cement content on the mechanical characteristics and acoustic emission behaviors were emphatically studied. The results show that the wave velocity and uniaxial compressive strength of artificial sandstone specimens with coarse particle size ( 0.425-0.85 mm ) are the highest under the same cement content. With the increase of particle size, the crack propagation stage of the specimen decreases gradually, and the acoustic emission energy rate and event rate near the peak strength point of the specimen increase. Under the same particle size condition, with the increase of cement content, the uniaxial compressive strength of the specimen decreases gradually, the acoustic emission event rate near the peak strength point decreases gradually, and the stress percentage value corresponding to the fractal dimension D value of acoustic emission amplitude decreases to the lowest value gradually. The fractal dimension D of acoustic emission amplitude is linear with the change of intensity.
- 1
Experimental study on rockburst characteristics of granite under true triaxial stress pathAbstract:
In order to analyze the influence of excavation and unloading on the failure characteristics of roadway surrounding rock under high stress conditions, the true triaxial rockburst test system was used, the failure form, energy evolution characteristics and basic characteristic parameters of acoustic emission of granite rock were studied by means of three-direction six-sided loading and single-sided rapid unloading. The test results show that the rock failure process is divided into four stages: small particle ejection, rock slab splitting, slab breaking and spalling, and block ejection. The sample formed a V-shaped rockburst pit on the unloading surface, and shear cracks appeared on the inner side, and the overall failure pattern showed a binary distribution in the spatial distribution; through the study of rock burst energy, it is found that the energy absorbed by the rock before the unloading process is mainly accumulated in itself by the releasable elastic strain energy, and the accumulated elastic strain energy is released after the unloading process, which promotes the breaking of the rock; the variation law of acoustic emission AF and RA eigenvalues shows that tension cracks and shear cracks occur in rock samples during the test, and shear failure is the main one. The damage variable curve of the rock has a good corresponding relationship with the stress curve, which can reflect the damage degree of the internal structure of the rock and provide a certain theoretical basis for the monitoring of deep engineering disasters.
- 1
Failure Instability and Energy Evolution of Coal-Rock MassAbstract:
In order to study the instability and energy accumulation and evolution of coal-rock mass under load, this paper constructed coal-rock, coal-rock-coal mass and rock-coal-rock mass models based on COMSOL numerical simulation software, and carried out uniaxial compression tests. The results show that: (1) Under the same loading conditions, the larger the proportion of coal components in the composite, the smaller the compressive strength limit. (2) The energy accumulated in the composite is converted into internal elastic strain energy and damage dissipation energy, and the released elastic strain energy is the internal mechanism of the failure of coal and rock mass. (3) The stress acting on the coal component and the rock component by uniaxial compression is equal, and the maximum stress is the compressive strength σ of the combination; the internal energy of the combination is mainly accumulated in the coal component, which is the The energy accumulation carrier for the deformation and destruction of the composite body. The research results can provide a theoretical basis for reducing the stability of coal seams containing gangue and improving the recovery rate of top coal.
- 1
Study on the Performance of Alkalized Long Diameter Rice Straw Modified Iron Tailing Cement Filling MaterialAbstract:
When deep shaft fillers are exposed to complex underground environments with high ground stress and high rock temperature, they are prone to cracking, instability, deformation, strength decay and other phenomena, which in turn induce geological disasters such as roadway deformation, roofing, sudden water surges and collapses. In order to investigate the variation of the rheological and mechanical properties of the filler slurry with the amount of straw and the length of straw, 16 sets of orthogonal tests with the amount of straw 0.25%, 0.45%, 0.65% and 0.85% and the length of straw 3 mm, 6 mm, 9 mm and 12 mm were designed. -The rheological parameters were tested with the aid of a soft solids rheometer, type SST, and fitted to the Hershel-Bulkley model.The results show that with the increase of rice straw doping and rice straw length, the more interfering settling flocs formed by the wrapping and flocculation of hydration products, the slurry viscosity and yield stress increase continuously. When the rice straw dose is 0.65% and the rice straw length is 9 mm, the compressive strength of the filler increases significantly, and the rice straw plays a bonding role in the filler, which increases the bonding and mechanical bite force of the filler; if the rice straw dose and rice straw length continue to increase, the number of dispersed rice straws per unit volume is too much, and the filler forms a stress concentration zone, which weakens the ability of the filler to resist deformation and thus reduces the mechanical properties of the filler.
- 1
Study on The Internal and External Staggered Arrangement and Stress Distribution Law of Lower Coal Seam Roadway in Close-Distance Coal SeamAbstract:
In view of the problems that the lower coal seam mining roadway is affected by the upper coal seam mining, the stress concentration of coal pillar and the difficulty of roadway support in the process of close-distance coal seam mining, this paper takes the two close-distance coal seams of 8# coal and 9# coal in Ximing Coal Mine of Shanxi Coking Coal Group as the research object. By comparing the advantages and disadvantages of internal dislocation and external dislocation, a layout method of mining roadway combining internal dislocation and external dislocation is proposed, and the influence of coal pillar width and roadway offset distance on the deformation of roadway under the coal pillar is analyzed. The results show that the combination of internal dislocation and external dislocation reduces the deformation of roadway and ensures the safe and efficient mining of lower coal seam. With the increase of the coal pillar width of the upper coal seam, the deformation of the surrounding rock of the roadway under the coal pillar decreases gradually, and the appropriate width of the coal pillar is 40 m according to the calculation of the field working condition. The surrounding rock stress of the roadway under the coal pillar of the upper coal seam is asymmetrically distributed, and the reasonable position of the roadway is directly below the coal pillar and 2m to the left. At this time, the stress distribution of the roadway roof and the two sides is basically symmetrical. The research results can provide reference for roadway layout of lower coal seam in close distance coal seam.
- 1
Study on the Development Process and Failure Characteristics of Induced Caving in Composite StrataAbstract:
The sublevel caving method must form a covering layer with qualified quality before normal mining. Based on the engineering background of a large non-ferrous metal mine from downward layered cemented filling method to sublevel caving method, the development process and failure characteristics of induced caving of composite roof strata composed of cemented filling body, gneiss and quaternary topsoil are studied by PFC discrete element numerical simulation method. The research results show that under the condition of Engineering induction, the special composite caving mode of "cemented filling arched loose body caving + gneiss integral rock column sliding + quaternary topsoil arched loose body caving" will occur in the composite rock stratum. After the first mining and sublevel mining, a loose overburden of no less than 30m thick can be formed. At the same time, in the process of caving mining, the fault failure time can be delayed by delaying the mining of the access road near the fault, So as to avoid geological disasters caused by fault damage. In addition, in the transition period, the caving stope and filling stope should be pushed from east to West as a whole. The two stopes should maintain space-time coordination in the pushing sequence and mining progress, so that the two stopes always maintain a large distance on the plane, and avoid the adverse impact of mining stress between different stopes, so as to ensure the safe and efficient collaborative mining of filling method and caving method. The research results can provide guidance for the actual production on site.
- 1
Effect of Hard Rock Intercalation on Creep Properties of Composite Rock and Its ApplicationAbstract:
In order to investigate the influence of hard rock interlayer on the creep property of composite rock mass, the variation law of axial deformation of composite rock mass with different number, thickness and spacing of interlayer was analyzed by combining test and numerical simulation.The results show that the creep of composite rock mass decreases with the increasing thickness and number of hard rock interlayers.The ability of hard rock interlayer to resist creep deformation can be increased by reducing the specific energy of shape change of soft rock in the affected area. However, with the increase of interlayer spacing, the ability of composite rock mass to resist creep deformation first increases and then decreases.By analogy, it provides some basis for the choice of grouting time of roadway surrounding rock.
- 1
Multi-scale Analysis of the Effect of Age of Maintenance on the Physical Properties of the Backfill MechanicsAbstract:
In order to investigate the influence of maintenance age on the mechanical properties of the backfill, ultrasonic testing, uniaxial compression test and SEM microstructure scanning were carried out on the backfill at different ages to analyze the influence of maintenance age on the mechanical properties of the backfill at three scales: macro-fine-micro. The results showed that: the longer the age of maintenance, the steeper the stress-strain curve of the backfill, the higher the peak stress and the higher the residual stress; the wave velocity, elastic modulus and compressive strength of the backfill gradually increased with the extension of the age, and the growth rate gradually decreased; the compressive strength and elastic modulus of the backfill have good exponential correlation with the wave velocity, and the growth rate of both increased with the increase of wave velocity; with the extension of the age of maintenance, the Ca(OH)2 crystals inside the backfill shrink, the morphology of calcium alumina evolves from slender needle-like to short thick columnar, the number of hydration products C-S-H reticular gel increases significantly, the number of pores and porosity decrease, the structural denseness increases, and the compressive strength of the backfill increases.
- 1
Research on the Role,Consumption and Demand of Rare and Dispersed Elements Mineral in Strategic Emerging IndustriesAbstract:
Strategic emerging industries are the industry with critical leading role and growth potential for the development of economy and society, and rare and dispersed elements mineral are a kind of key raw materials to support the development of strategic emerging industries. Therefore, it is very important to clarify the role, consumption status and demand of rare and dispersed elements mineral in strategic emerging industries. Based on industrial development and current situation of mineral resources, this paper analyzes the consumption status of rare and dispersed elements mineral in strategic emerging industries by using the combination of " the industrial chain" and " reverse the industrial chain", and then predicts the demand of rare and dispersed elements mineral in strategic emerging industries during the "14th five-year plan" by using ARIMA model and Braun model. The results are shown that: (1) In 2020, rare and dispersed elements mineral was mainly applied four primary industries such as new generation information technology industry, new material industry, involving more than 30 kinds of important products. Among them, the new material industry was the most applied field, and the consumption proportion was as high as 93.38%; (2) In 2020, the consumption of rare and dispersed elements mineral in strategic emerging industries was 3672.89 tons (metal), accounting for 30.82% of the total consumption. (3) In 2025 of during the "14th five-year plan" period, the total demand will reach 6747.93tons, accounting for 35.8% of the total consumption.
- 1
Discussion on Mesh Division in Numerical Simulation of Stability of Downward Layered Filling ApproachAbstract:
In order to study the influence of mesh size on the numerical simulation results of downward layered filling drift stability, three drift stope models with different mesh sizes are established. Based on the mechanical test results of indoor filling bodies with different sizes, the stability of stope after drift excavation are simulated and analyzed. The results show that the smaller the mesh size is, the smaller the variation of the roof displacement of the model route is. With the increase of the distance between the overlying backfill and the roof surface, the overlying backfill changes from tension to compression. The smaller the mesh size, the greater the maximum principal stress of the roof surface corresponding to the model. In the two sides of the route, the corresponding models of the three size meshes are under compressive stress. The difference among the three of them is not obvious. The plastic zones of the three mesh models are located at both ends of the route roof, which are long strips. And with the increase of mesh size, the depth increases. The stability of downward layered filling approach will change with the different mesh sizes. Therefore, the mesh size of the numerical model of different optimization schemes should be consistent when designing the optimization scheme of the mine.
- 1
Research Progress of Open-Pit Production and Transportation Equipment ManagementAbstract:
With the acceleration of scientific and technological innovation and the change of production modes, mining equipment presents a trend of refinement, diversification and intelligence. By analyzing the latest research topics of open-pit mine production and transportation equipment management, comprehensively reviews over 60 relevant papers mainly published in recent six years; classifies them into three categories (i.e., truck-shovel, crushing and conveying and hybrid mining equipment systems); and introduces the objectives, models, algorithms and results. In this review, main characteristics and limitations of related research on three equipment management systems are discussed in detail. Finally, this study proposes insightful suggestions on future research agendas, indicates the significance of advancing mining equipment scheduling methodologies, discusses the necessity of their real-world applications to improve equipment timetabling management, and emphasizes the future challenges such as autonomous technology, intelligent navigation, multi-system integration, and multi-index evaluation.
- 1
Research on Lightweight Optimization of Yolo-V5 Detection Model for Truck Driver Driving Behavior in Open-pit MineAbstract:
In view of the defects of Yolo-V5 target detection algorithm in the application of open-pit mine, such as low model fitting ability, large memory occupied by real-time target detection and high equipment configuration requirements, a fusion optimization strategy is proposed to study the lightweight optimization of Yolo-V5 model. In the model training stage, momentum was introduced to improve torch.optim.SGD() algorithm, and optimized the training weight of the model, sped up the training convergence speed and enhanced the fitting degree of the model; After model training, the Yolo-V5 model was pruned at the network layer and quantified as fp16 in the OpenVino environment. The model volume was compressed by 75% and the computing memory was reduced by 33.88%. Through laboratory comparative experiments, the following conclusions are drawn: compared with GPU equipment, the detection model using fusion optimization strategy improves the inferential FPS by 83.71% on low configuration CPU equipment, reduces the average inferential time by 45.11%, reduces the detection warning time of 8 types of driving behavior by 9.89%-82.21%, and improves the detection accuracy of smoking, eating and drinking and mobile phone by 3.34%-10.00%. The results show that the fusion optimization strategy realizes the research goal of Yolo-V5 lightweight optimization, and the real-time target detection gets rid of the dependence on GPU equipment, which makes a good research foundation for the further application and popularization of Yolo-V5 target detection in open-pit mine.
- 1
Study on the Effect of Iron Tailings Aggregate on Pervious ConcreteAbstract:
Based on the properties of iron tailings aggregate, the effects of single and double gradation of iron tailings aggregate (4.95mm-9.5mm and 9.5mm-16.5mm) on the mechanical properties of pervious concrete and the microscopic properties of pervious concrete from iron tailings are studied. In the experiment, the water cement ratio of 0.28 was used to prepare the pervious concrete specimen with a porosity of 20%. The compressive strength and connected porosity of the pervious concrete specimen were tested, and the macroscopic bonding surface and interface transition zone were observed by optical microscope and scanning electronmic- roscope.The results show that single-grain pervious concrete with iron tailings has its optimal particle size range. Compared with limestone aggregate, the compressive strength of pervious concrete is higher when the particle size of iron tailings aggregate is greater than 9.5mm. When the ratio of small particle size to large particle size is 3:7, the concrete has the best performance, the compressive strength is 18.1MPa, and the porosity is 22.2%. Compared with the control group, the interfacial transition zone of pervious concrete with iron tailings has poor compactness and more fine cracks, but it has better mechanical bite with hardened cement slurry.
- 1
The Application of Improved k-means Algorithm Based on Gray Difference for Segmentation of Coal Mine ImagesAbstract:
Coal mines image has the characteristics of non-uniformity and low illumination caused by its special conditions, which bring difficulties to image segmentation. Aiming at the problem of non-uniform and low illumination coal mine image segmentation, an improved k-means image clustering segmentation algorithm is proposed based on gray difference in this paper. Firstly, the gray difference statistical features of the image are calculated, including contrast, entropy and average value. The gray difference statistical features are used to describe the texture features of coal mine images, and the feature vector is established. Then, the distance function between samples and cluster center is established based on the texture feature vector, and the optimization problem is constructed through the criterion function of K-means algorithm. Finally, according to the clustering results of the optimization problem, the target segmentation of coal mine images are realized. The evaluation indexes of experimental results of the two groups of coal mine images are increased by 12% on average. Combined with the segmentation visual effect, it shows that the improved method can realize the effective segmentation of coal mine images and produce a better segmentation effect.
- 1
Research on Autonomous Height Adjustment Strategy of Shearer Based on Implicit Digital TwinCAI Anjiang, 刘俊强, 刘亚东, 任志刚
Abstract:
Aiming at the problem that the traditional control method has hysteresis and is difficult to realize the autonomous elevation control of shearer, the implicit digital twin model ( IDT ) of the autonomous elevation of the shearer is constructed, and the efficient autonomous elevation of the shearer is realized. A shearer cutting trajectory prediction method driven by IDT and long-short-term memory neural network ( LSTM ) is proposed. The honey badger algorithm ( HBA ) is used to optimize the super-parameters of LSTM for the first time. The results of example analysis show that the honey badger algorithm optimizes the long-short-term memory neural network ( HBA-LSTM ) has higher accuracy than the ordinary LSTM. The control strategy of independent height adjustment of shearer based on implicit digital twinning is proposed. Its structure includes three parts : data acquisition, IDT model and independent height adjustment of shearer. The control term is introduced in the independent height adjustment part to correct the control parameters of shearer. The example simulation shows that under the IDT environment, the self-elevation trajectory curve of the shearer after parameter correction is closer to the actual elevation trajectory of the shearer, and the maximum error is 0.028, which effectively improves the adaptability of the automatic elevation of the shearer.
- 1
Optimization Of Stope Structure Parameters Based On IAHP-TOPSIS Model With Downward Approach Filling MethodAbstract:
In order to solve the problems of low single-shot blasting quantity, low mining efficiency and high mining cost in the downward approach cement filling mining method in the third mining area of Jinchuan Group. This paper firstly conducts field tests of the stope approach with different section sizes, and obtains the maximum vertical compressive stress of the stope approach roof, the maximum subsidence of the roof and the maximum convergence deformation of the two sides through the field test, and then uses the analytic hierarchy process ( AHP) and TOPSIS comprehensive evaluation model, established a comprehensive evaluation system considering the influence of five factors including safety, economy, technology, external conditions, and environmental conditions, and optimized the optimal section size. The research results show that: the stope approach with three different section sizes has the highest safety and the highest production efficiency. The section size of the stope approach is 5.0m*4.5m, and it also shows that the AHP-TPOSIS method is suitable for the down-entry filling method in the stope. Effectiveness in structural parameter optimization.
- 1
Study on Slip Deformation Law of Hexi Slag Field in Shuichang Iron Mine during Rainy SeasonAbstract:
Slag soil field is a loose accumulation body. Since the loose body is prone to collapse and debris flow after encountering water, it is of practical significance to study the influence of different rainfall intensities on the slope stability of slag soil field. Taking the B-B section of Hexi slag field in Shougang Waterworks Iron Mine as the research object, the spatial slip deformation law of slag field was studied by numerical simulation, and the slope stability was simulated under seven different working conditions of nature, light rain, moderate rain, heavy rain, rainstorm, heavy rainstorm and extraordinary rainstorm. The horizontal stress and vertical stress of soil inside the slope were systematically analyzed, and the curve distribution map was drawn. The slip field theory method is used to search the local slip surface and the overall slip surface of the current slag field, and the safety factor of the slope under different working conditions is determined according to the three evaluation methods in the specification. The evaluation results show that the slope of the slag field is in a stable state as a whole, but the slope is in an unstable state under three working conditions of heavy rain, heavy rain and extraordinarily heavy rain, and the slope is in a critical state under five working conditions, indicating that local collapse damage is easy to induce. The slope of + 175 platform and + 220 platform should be strengthened, and the intelligent monitoring and early warning analysis system should be established according to the requirements of relevant specifications or regulations.
- 1
Research on reasonable width of coal pillar in fully mechanized caving face section of thick coal seamGAO Linsheng1,2,DENG Guangzhe1,SUO Yonglu1,QIU Haitao2Abstract:
In the industrial practice of thick seam top coal caving mining, the parameters of section coal pillar have great correlation with the stability of roadway surrounding rock. When the section coal pillar is small, the stability of roadway surrounding rock is poor. Affected by mining, it is easy to have accidents such as roadway wall extrusion and roof caving, while the width of coal pillar is too large, which will cause great waste of resources Through laboratory test, theoretical analysis, numerical simulation, field measurement and other research means, and considering the influence of the maximum principal stress on the stability of roadway surrounding rock, the parameters of coal pillar in thick seam caving mining section are optimized. On the premise of ensuring the stability of roadway surrounding rock, the width of coal pillar in roadway protection section is reduced as far as possible, which improves the economic benefit of the mine and solves the problem of Lu"an mine This paper discusses the problem of coal pillar setting in No.3 top coal caving face, and provides scientific basis and beneficial guidance for coal pillar setting in thick seam fully mechanized top coal caving mining under similar engineering conditions.
- 1
Study on the inhibitory effect of new fire fighting gel on coal active molecular groupsAbstract:
In order to study the inhibitory effect of gelatin on the active molecular groups of coal spontaneous combustion, a new gel is prepared using a sulfate crosslinking agent and a phosphate geller cross-blending experiment, and the effects of different mass gels on coal resistance were studied by temperature programmed experiment, Fourier transform infrared spectrum Test and peak fitting processing. The distribution characteristics and changes of 4 groups of hydroxyl, carbonyl, carbon carbon double bond and carbon oxygen single bond before and after gel treatment were studied. The results show that the amount of CO gas produced by gel treatment of coal samples is significantly lower than that of raw coal, and the inhibition rate of coal samples with 30g, 60g and 90g gels is 37%, 54% and 65% respectively, with the increase of coal temperature; and after gel treatment, the activity of functional groups contained in coal can be effectively reduced, the absorbance and peak area of the four molecular groups of coal samples decreased significantly, with an average decrease of 52.59% and 56.52%; the new fire fighting gel has a significant inhibiting effect on the spontaneous combustion of coal molecular groups, and the inhibition effect on the carbon oxygen single bond and carbonyl group is better than the carbon carbon double bond and hydroxyl group.
- 1
Study on Strength Characteristics of Soil Reinforcement Materials in Heap Leaching Site of Ion Rare Earth MinesAbstract:
Heap leaching technology on mining of rare earth ionic disused mines sparse vegetation growth, geological disasters such as serious soil and water loss. In order to improve the local soil and improve the strength of the soil, the waste rare earth mine in datangwei, Dingnan county is taken as the research area, and the soil reinforcement materials are made of bentonite, sodium bicarbonate, waterborne polyurethane, cement and water in a certain proportion, The developed reinforcement material is used to strengthen the soil of abandoned rare earth mines in ion heap leaching site. The change of soil shear strength is tested by indoor direct shear test. The test results show that the shear strength of the soil has been significantly improved, in which the cohesion has increased by 145.54%, and the variation of the internal friction angle is not obvious; under the action of lower vertical stress, the stress "hardening" potential of the reinforced soil decreases, and the shear failure type changes to stress "weakening". The research results provide a theoretical basis for ecological restoration and soil and water conservation of this kind of sites.
- 1
Bearing Fault Diagnosis Method of Shearer Traction Part Based on ADAMSAbstract:
due to the complex and compact structure of the shearer traction part, it is difficult to diagnose the bearing fault of the shearer traction part. Aiming at this problem, a bearing fault diagnosis method of shearer traction part based on ADAMS is proposed. Firstly, taking the idler bearing of the traction part of MG210 / 485-WD thin seam shearer as the research object, the virtual prototype technology is used to collect the simulation vibration signals of the bearing under four states: normal, inner ring fault, rolling element fault and outer ring fault; Then the simulation signal is imported into Matlab for empirical mode decomposition.The results of signal processing and algorithm classification show that this method can effectively realize the classification of bearing fault category and provide a new method for bearing fault diagnosis of shearer traction part.
- 1
Regulation Mechanism of Surfactant on AnthraciteAbstract:
In order to reduce the harm of dust to human body, through the combination of molecular simulation and experimental analysis, the control mechanism of surfactant on the wetting of anthracite was comprehensively explored from both macro and micro perspectives. The molecular dynamics simulation of spatial distribution, the key interactions, hydrogen bonding interaction to compare anionic/non-ionic surface active agent on the similarities and differences between anthracite coal wetting, experimental reagents: going to use AEO-9, NP-10, SDBS, Rapid Penetrant T, dynamic surface tension experiment to explore the modification effect of reagents for water, infrared spectrum experiment explore reagent modified effect of anthracite coal. The results show that the surfactants are oriented at the liquid-solid interface, but the anionic surfactants have stronger order. Anionic surfactants have higher electrostatic force than non-ionic surfactants, and lower hydrogen bond force than non-ionic surfactants. The four reagents can greatly reduce the surface tension of water. The hydrophilic group is improved and the wettability is enhanced after the reagent is treated with anthracite. The wettability of Rapid Penetrant T is the most "mild".
- 1
Experimental Study on Mechanical Properties of Modified Concrete Filling Beside Gob Retaining RoadwayAbstract:
Concrete, as a backfill material for gob-side entry retaining roadside support, improves the strength of roadside support, but the plastic deformation capacity of ordinary concrete materials is small, it is difficult to coordinate the deformation, and it cannot adapt to the deformation of the roadway with large deformation under high in-situ stress,resulting in the difficulty of reusing the lanes. Aiming at the limitations of the current gob-side entry retaining and filling body concrete materials, on the basis of replacing 15% cement with fly ash to increase the strength of the concrete specimen, the introduction of ethylene-vinyl acetate polymer (Ethylene Vinyl Acetate polymer, EVA) to modify the concrete material,. Two different loading rates of 0.03mm/s and 0.01mm/s were used to test the uniaxial compressive strength of concrete with different EVA contents. Experiments show that the addition of EVA improves the plastic deformation ability of concrete, improves its compressive property, and the compressive property increases with the increase of EVA content within a certain range, and the best effect is when the EVA content reaches 15%, and a downward trend at 20%. Then through the analysis of mechanical properties, it is concluded that the effect of polymer on concrete compressive property is achieved by inhibiting the propagation of cracks when concrete is compressive. And it is found that the acoustic emission energy is in good agreement with the variation of stress-strain curve.
- 1
Numerical simulation analysis of cooling effect of spraying thermal insulation material in roadway of west section of Dahongshan Copper MineAbstract:
With the increase of deep mining activities, more and more mines are facing the problem of mine heat damage caused by geothermal heat. In order to discuss the cooling effect of high-temperature roadway surrounding rock after spraying thermal insulation material, taking the west mining section -20m middle section of Dahongshan Copper Mine as the research object, the thermodynamic parameters of surrounding rock were tested. And the Ventsim software was used to carry out the simulation analysis of the cooling effect of spraying thermal insulation material in the whole area of the -20m middle section, and further analyze the cooling effect of spraying thermal insulation material in the local roadway area under different air inlet conditions. The results showed that the average cooling effect was 1.12℃ after spraying the thermal insulation material in the whole area of the middle section of -20m, and the overall cooling effect was not good. When the local roadway was sprayed with thermal insulation material and the inlet air flow temperature was less than 28°C, the cooling effect of the sprayed thermal insulation material could meet the requirements. Spraying thermal insulation material can be used as an auxiliary cooling measure to prevent heat damage in local areas.
- 1
Research and Application of Static Presplitting Technology of Roof Before Initial Mining in High Gas MineAbstract:
Aiming at the problem of the length of the initial pressure step in high gas mining, a technical scheme of static pre-split treatment for cutting hole before initial mining was proposed. Through analyzing the principle of static pre-splitting designed on the basis of the test system and core components, the static the hulking agent (SCA) axial and radial expansion pressure and inflation pressure was determined, the design and self-control, a lap antiskid directional static pre-splitting shaped device in small coal roof pre-splitting field test of 30218 cut. The results show that the expansion pressure of static expansion agent increases with the increase of pipe diameter, and the radial expansion pressure is higher than the axial expansion pressure when the pipe diameter is constant. The effect of roof presplitting was verified by UDEC numerical simulation and in-situ drilling. The results of industrial test show that the static presplitting device can focus the radial expansion pressure directively, strengthen the presplitting effect of roof, and simplify the static presplitting process. After the static presplitting of the cutting roof, the first step distance is reduced by 10.8 m, which achieves good industrial results and meets the requirements of safety production.
- 1
Study on Selection of Mining Equipment with Cantilever Roadheader in Metal MineAbstract:
In order to ensure the mining efficiency of cantilever roadheader and the matching adaptability of the whole production system, the principle of equipment matching selection was summarized, and the method of equipment matching selection for roadheader, ventilation and dust removal and power supply system was put forward. Machine type selection, according to the mining engineering, design of primary equipment, seted up the relationship between rock uniaxial compressive strength, shear strength and cutting force required for rock breaking model, compared the cutting force provided by primary equipment and broken rock cutting force, surplus coefficient concept was put forward, on the basis of the guarantee ability of broken rock, models had surplus coefficient of reasonable been choiced.On the supporting equipment, through calculating the main parameters of ventilation, power supply and distribution system equipment, according to the calculation results the main equipment been selection. Select a mining area to verify the selection method, the results showed that: the industrial test selected EBZ160 type cantilever roadheader with a surplus coefficient of 209% been carried out , the production efficiency increased maximumly 3.56 times in one day, the equipment selection of ventilation system and power distribution system matched the production requirements, which proved the applicability of the selection method in mechanical mining of metal mines.
- 1
Influence of Microwave Heating Path on Mechanical and Energy Properties of GraniteAbstract:
To explore the changes of mechanical and energy properties of granite under different microwave heating paths, various microwave heating paths were set to heat the rocks by controlling the heating power and heating duration. Furthermore, uniaxial compression tests were conducted to analyze the changes of mechanical properties of the damaged rocks after microwave irradiation, and the evolution laws of elastic energy and dissipation energy of the rocks during deformation and damage were also evaluated through energy theory. The results indicate that: (1) under microwave heating, compared with the heating duration, the heating power causes more damage to the rock.Rock thermal damage has a damage mutation threshold, and the damage increases sharply beyond this threshold
- 1
STUDY ON ADSORPTION OF HEAVY METAL IONS IN MINERAL PROCESSING WASTEWATER BY MODIFIED WASTE BASALT FIBERAbstract:
Continuous basalt fiber is a new kind of high performance fiber. Due to the influence of impurities in raw materials, a large number of broken wires and flying wires often occur in the production process, which leads to a new type of solid waste - waste basalt fiber. Using the waste basalt fiber as the carrier, the basalt fiber adsorbent was prepared by surface modification to realize the adsorption treatment of heavy metal ions in mineral processing wastewater. In order to explore the way of fiber modification, FT-IR and SEM were used to characterize the fiber. The effects of addition amount, pH value and adsorption time on the adsorption of Cu and Pb ions were investigated. The results show that the optimal removal rate of the two metal ions can reach 83.38% and 83.87% when the dosage of modified fiber is 0.8 mol?L-1, pH is 7 and adsorption time is 4h. The adsorption conforms to the quasi-second-order kinetic model. If the modified basalt fiber is used in the treatment of mineral processing wastewater, the Cu2+ and Pb2+ ions in the wastewater can meet the relevant national discharge standards, and waste treatment by waste will be completely realized.
- 1
Numerical Simulation of Coal Seam Gas Mining Based on Microwave Heat InjectionAbstract:
In order to study the law of coal seam gas migration and recovery under microwave heat injection, based on the electromagnetic thermal fluid solid coupling model of microwave heat injection gas drainage, the numerical simulation of gas drainage under microwave heat injection is carried out, and the evolution law of coal seam temperature and gas production under different microwave frequency, microwave power and initial permeability are analyzed. The numerical simulation results show that the coal seam temperature at the heat injection site increases rapidly during microwave heat injection. With the increase of heat injection time, the high temperature range continues to expand from the heat injection site to the gas well through heat transfer and heat convection; Comparing the two different microwave frequencies of 0.915ghz and 2.45GHz, low-frequency microwave is more conducive to enhance the microwave thermal effect; Comparing four different microwave powers of 0W, 500W, 1000W and 1500W, compared with conventional mining, microwave heat injection greatly promotes gas desorption and migration, and the gas content is greatly reduced. Increasing microwave power plays a positive role in improving gas production; Gas recovery can be further improved by increasing initial permeability with microwave heat injection.
- 1
Study on 3D Model Reconstruction and Fracture Process of Irregular Sandstone ParticlesAbstract:
Three-dimensional model reconstruction of sandstone particles based on digital image processing technology and three-dimensional fracture process analysis program RFPA3D-CT, Failure mechanism and fracture process of real mesoscopic heterogeneous mechanical model of irregular sandstone particles under uniaxial compression are simulated. The results show that the fracture mode of irregular specimen changes from single crack to multiple cracks under uniaxial compression, and the crack direction forms a certain angle with the principal stress direction; With the increase of stress, the generation, development and penetration of tensile failure elements in the specimen lead to the formation of macroscopic shear fracture zones in the middle of the specimen; Most of the energy released by the rock specimen during the fracture process comes from the fracture zone in the high stress area, especially the fracture zone near the end of the specimen with a small contact area with the loading plate. In addition, it is also found in the simulation process that the more spherical the specimen is, the longer the linear behaviors of the stress-strain curve is, and the greater the strength is. The research results are of great significance to discuss ore and rock fracture mechanism and explore the high efficiency energy saving rock fragmentation methods.
- 1
Experimental study on the amplitude characteristics of rock transmission waves under the action of water pressure and ground stressAbstract:
Deep resource extraction and deep buried tunnels and other rock engineering are mostly in a high water pressure and high ground stress environment. Under dynamic load disturbances such as blasting excavation and seismic hazards, dynamic loads are propagated in the form of stress waves in the rock mass, and the study of rock stress wave propagation characteristics is the basis for analyzing and assessing the stability of the surrounding rock mass under the action of dynamic loads. In order to study the effects of different magnitudes of water pressure and ground stress on the propagation characteristics of rock stress waves, an experimental study of stress wave propagation was carried out on saturated red sandstone by using a homemade high water pressure and high stress rock stress wave propagation test system, setting six water pressure and four axial static stress levels, analyzing the variation of transmitted wave amplitude with water pressure and axial static stress, and constructing its empirical model. The results show that when the impact velocity and axial static stress are certain, the transmission wave amplitude increases as a power function with the increase of water pressure, but the increase is smaller and smaller. This is due to the lateral constraint effect of water pressure itself, the bending liquid surface effect and Stefan effect inhibit the expansion of pores inside the rock and strengthen the penetration ability of the stress wave in the rock. When the water pressure is certain, the greater the axial static stress, the smaller the amplitude of the transmitted waves. The higher the axial static stress, the more sensitive the transmission wave amplitude increases with the water pressure. The results of the study can provide theoretical basis for the stability analysis of the surrounding rock body during blasting excavation in deep high water pressure engineering.
- 1
Beneficiation experiment and industrial practice of recovering iron from molybdenum tailingsAbstract:
A Molybdenum flotation tailings in Luoyang contains 12.71% iron, of which the magnetic iron content is 8.15%. It wastes resources and shorts the service life of the tailings pond.SSIn order to reasonably recover iron resources in the molybdenum tailings, according to the characteristics of the ore, the process tests such as rough separation and tailing dumping, vertical mill separation and magnetic levitation separation and cleaning were carried out.SSThe results show that the process of "rough separation and waste discarding -- vertical mill re-separation -- magnetic suspension cleaning" is adopted, that is, the molybdenum tailings were preenriched at 400mT magnetic field strength, and then the magnetic products were finely ground to 87% of -0.045mmfor wet weak magnetic roughing at 260mT and cleaning at 180mT field strength, respectively, and then the obtained concentrate was purified by magnetic levitation under the condition of 14L/min upflow.SSFinally, iron concentrate powder with magnetic iron grade of 63.727% was obtained with magnetic iron recovery of 96.15%.
- 1
Study On Synergetic Mining Technology of the Orebody with Complex Geological Conditions In a Certain Gold MineAbstract:
Aiming at the mining technical problems of the orebody with complex geological conditions, by analyzing the occurrence of ore body and engineering geological conditions, the idea of mining method optimization with complex geological conditions was put forward. Based on the existing mining methods, the upward drift filling method was selected to mine unstable or medium thick and thick orebody, and the on-site industrial test was carried out. The test results show that the upward drift filling method is suitable for the orebody mining with complex geological conditions, which can effectively improve the mining safety and resource recovery rate, and can be promotion and applied in mines.
- 1
Study of the Stress Evolution Law of Floor Roadway and Stability of Surrounding Rock under Mining DisturbanceAbstract:
In order to study the instability of surrounding rock in-floor gas drainage roadway induced by mining disturbance, this paper takes the 5921 floor gas drainage gateway of Longfeng Coal Mine as the engineering background. The numerical simulation method is used to analyze the stress evolution process of the surrounding rock and the deformation and failure characteristics of the surrounding rock during the mining process of the 5921 working face. The results show that the vertical stress increases with the increase of depth within the roadway span,the roadway is located in the front of the working face, and the stress distribution characteristics of the surrounding rock are roughly the same, the roadway is located in the goaf, the left rock mass is unloading, and the right rock mass has obvious stress concentration; the deformation of surrounding rock has a certain lag compared with the mining of working faces in time and space, the maximum deformation position of the bottom extraction roadway lags behind the mining working face by about 10m-30m, and the deformation of surrounding rock within 10m in front of the working face has an increasing trend; the failure of the part of the floor roadway located in the goaf is mainly a tensile failure, and the failure of the part located in the supporting pressure area in front of the coal wall is mainly tensile shear combined failure mode, the risk of roadway roof collapse and floor heave is high.
- 1
Adsorption Behavior of Polystyrene Nanoparticles on Carbon and Quartz SurfacesAbstract:
Polystyrene (PS) nanoparticles can be used as collectors in slime flotation, but the poor adsorption selectivity leads to excessive reagent consumption. Therefore, exploring the adsorption behavior of PS nanoparticles on the surface of carbon and quartz is of great guiding significance to reduce the adsorption of nanoparticles on the surface of non target minerals during flotation, so as to reduce the dosage and reduce the cost.The cationic PS nanoparticles were prepared by emulsion polymerization. The adsorption desorption behavior of nano particles on the carbon surface and quartz surface under different conditions was studied by using the quartz crystal microbalance with dissipation monitoring (QCM-D).The results show that under different conditions, particles will produce irreversible adsorption on quartz surface and carbon surface, and the adsorption capacity of the former is about 2 / 5 of that of the latter, which explains why the consumption of traditional Chinese medicine is large in the actual flotation process; Reducing the solid content of the emulsion is more obvious to inhibit the adsorption of particles on the carbon surface. For example, when the solid content is reduced from 21g/L to 15g/L, the adsorption capacity of the carbon surface is reduced by 18.16% as much as 8.49% of that of the quartz surface. Therefore, it is not advisable to reduce the solid content and inhibit the adsorption of particles on the surface of the non target minerals in the actual flotation process. Acidic (pH = 5) and alkaline (pH = 9) conditions inhibited the adsorption effect of nanoparticles on the quartz surface, and the adsorption capacity decreased by 5.21% and 9.47% respectively, but the reduction range on the carbon surface was 9.92% and 19.29%. Therefore, the pulp environment with pH = 7 during flotation was more conducive to the adsorption of particles on the coal particle surface; With the increase of adsorption capacity, the adsorption layer on the carbon and quartz surface becomes more dense, and the compactness of the carbon surface is less than that of the quartz surface. While the high solid content or neutral environment promotes the adsorption on the carbon surface, the configuration of the adsorption layer also becomes more loose, but the washing of water flow is always insufficient to overcome the desorption phenomenon caused by the adsorption energy barrier of particles.
- 1
Study on groundwater treatment scheme of slope in baren open pitAbstract:
Aiming at the Barun open stope, in the light of analyzing the engineering geology and hydrogeological terms of the mine field, an on-site investigation was carried out on the water outlet point in the mine field, and it is pointed out that it is necessary to treat the groundwater in the stope slope of Barun open stope in the process of mine production. Under the detailed analysis of the exploration information of the mine field and the work done by predecessors, two drainage schemes of well point precipitation method and inclined drainage hole method are proposed, and Through comparative analysis, the optimal scheme is obtained. In the end, slide is used to study the stability of open stope slope before and after drainage. The outcoms reflect that: Using Visual MODFLOW software to simulate and analyze the decreasing water result of the inclined drainage hole scheme is better than that of the well point precipitation scheme, and the total construction cost of the inclined drain hole is lower than that of the light well point dewatering scheme, so the inclined drainage hole scheme is selected as the final precipitation measure; The slope stability safety factor k after drainage is increased by 54.30% compared with that before drainage. The drainage effect is remarkable, and the drainage scheme is feasible, which can provide ideas for solving similar problems.
- 1
Construction and Application of Slope Collaborative Monitoring and Early Warning System in Wushan Open Pit MineAbstract:
The mining depth on the east side of the north section of Wushan copper-molybdenum mine reaches 245 m. With the increase of mining depth, the stability and safety of rock mass are getting worse and worse, and the problem of geological disasters caused by rock mass failure and instability becomes more and more prominent, which seriously restricts the safety production and economic benefits of mines. This project identifies landslide risk areas based on the information volume method, and conducts multi-source monitoring in high-risk areas. Through engineering case investigation and literature retrieval, a database containing 48 open-pit mine slope landslide cases was constructed, and the early warning threshold was extracted according to the case database search and matching, finally build a mine slope monitoring and early warning system based on WebGIS. Studies have shown that the risk level of landslides in parts of the west, southwest and southeast areas on the east side of the north mining section of Wushan Copper-Molybdenum Mine is relatively high. A monitoring and early warning system has been established for these areas and works well to ensure safe production and economic benefits of the mine.
- 1
Experimental study on classified fine tailings backfillingAbstract:
Affected by the increase in the fineness of tailings and the tightening of environmental protection policies and regulations, some domestic mines have begun to adopt the mining mode of "classified fine tailings backfilling and comprehensive utilization of coarse tailings". However, changes in tailings gradation will inevitably lead to changes in tailings thickening, backfill slurry transport, and backfill strength. Therefore, an experimental study on classified fine tailings backfilling in a gold mine was carried out, it includes the basic property test of the backfilling material, the tailings thickening characteristic experiment, the loop pipe experiment, and the backfill strength experiment. The results showed that: classified fine tailings compared with the unclassified tailings, the content of particles below 25μm increased by 17.18%, and the content of particles above 150μm decreased by 7.61%. The thickening efficiency of classified fine tailings is not as good as that of unclassified tailings, compared with unclassified tailings, the feed concentration of classified fine tailings is reduced by 2.65%, the addition of flocculant is increased by 10g/t, and the treatment capacity is reduced by 0.23t/m2·h. The conveying performance of classified fine tailings slurry is not as good as that of unclassified tailings slurry. In the case of slurry flow rate of 1.47m/s, 2.06m/s, 2.45m/s, the pressure loss of the pipeline with unclassified tailings slurry with a mass concentration of 66.15% is reduced by 36.46%, 39.37% and 40.17%, respectively, compared with the pipeline pressure loss of the classified fine tailings slurry with a mass concentration of 64.13%. The strength of classified fine tailings backfill is lower than that of unclassified tailings backfill. Compared with unclassified tailings backfill, the strength of the classified fine tailings backfill corresponding to the slurry state and the cement-sand ratio decreased by 2 to 5 times in 3 days, and decreased by 1.4 to 3.3 times in 28 days. The research results have guiding significance for the construction of classified fine tailings backfilling system in this mine, at the same time, it provides a certain reference for similar mines to use classified fine tailings as backfilling aggregate for underground backfilling.
- 1
Study on the development pattern of surface fractures in the mining of extra-thick coal seams in loess gully areasAbstract:
The surface cracks induced by large-scale coal mining in loess gully region aggravate the damage of regional ecological environment. Taking 61202 working face of DaFanPu Coal Mine in Inner Mongolia as the research object, the plane distribution law of surface cracks in working face was explored, the development characteristics of cracks in different regions were analyzed, and the mechanism of surface cracks in the process of mining was revealed. The results show that: (1) Around the open hole, it is easy to produce tensile cracks along the edge and settlement pits with "O" shaped distribution in the central area; In the middle of the working face, arc-shaped step cracks and tensile cracks in the edge area are distributed along with the advancing trend of the working face. The surface cracks near the stop-mining line are mainly C type tensile cracks. (2) The overall working face is dominated by cracks with a width of 10~30cm, and the drop of most cracks is between 5~20cm. (3) During the mining process of the working face, cracks in the roof continuously develop through the surface and produce ground cracks. With the advance of the working face, the crack width increases to the maximum and then decreases until it tends to close. (4) Along the trend direction of the working face, a circular fracture distribution area is formed around the surface subsidence area, and the fractures in the edge area develop continuously, and the fractures in the front of the working face advance show a trend of "development-closure". The research results are of great significance to the coordinated development of coal mining and regional environmental protection in loess gully mining area in western China.
- 1
Effect of nano SiC compounded with PVA on early strength of mining cement sealing materialAbstract:
Cement-based pore sealing material has problems of low early strength, self-shrinkage and high loss rate in harsh coal mine working environment. Nano-sic is added on the basis of cement and polyvinyl alcohol (PVA) is combined with polymer material. The effect of nano-sic compounding with PVA on the properties of cement-based sealing materials was studied by mechanical test, such as setting time, XRD, SEM, TG-DSC and microstructure analysis. Test conclusions: When the mass ratio of SiC was 0.3% and the mass ratio of PVA was 0.2%, the early strength of cement sample was significantly improved. The compressive strength of cement sample at 1d, 3D, 7d and 28d was 15.441mpa, 26.091MPa, 34.273mpa and 48.673MPa, respectively. Compared with blank group at the same age, they increased by 115.45%, 50.33%, 24.39% and 39.89%, respectively, and the final and initial setting time was significantly shortened. According to microscopic analysis, the experimental group of nanometer SiC and PVA mixed uniform internal closer, nanometer SiC filled the sample internal space, reduces the porosity, the mutual penetration of membrane structures at the same time, improve the internal structure of cement, polymer film can improve the compressive and tensile performance of cement, bring more excellent structural strength.
- 1
Mechanical properties and failure characters of rock affected by combined fissures and dip anglesAbstract:
Based on PFC numerical simulation software, the numerical models of defective rock mass with different fracture dip angles are established, and uniaxial compression experiments are carried out to study the mechanical characteristics and deformation and failure mechanism of defective rock mass with different fracture dip angles. The results show that the peak strength and peak strain of fractured rock show a trend of first increasing, then decreasing and then increasing again with the increase of fracture dip angles; When the fracture dip angle is 60°, the peak strength and peak strain of rock are the smallest; Under the influence of different fracture dip angles, the crack initiation stress and damage stress of fractured rock are obviously lower than that of intact rock, and its micro-cracks develop earlier than intact rock, and first occur at the crack tip; Due to the different propagation direction and distribution range of micro-cracks in rock, different forms of rock failure occur, which can be divided into two types: tensile failure and shear failure; Due to the existence of fracture defects,the bearing capacity and fragmentation degree of fractured rock mass are obviously reduced, among them, the bearing capacity and fragmentation degree of the defective rock with 90° fracture dip angle are obviously higher than those with 0 ~ 75° fracture dip angle.
- 1
Study on the Deformation and Damage Characteristics of Segmental Roadways under Collaborative Mining in the Three Middle Sections of Jinchuan III MineAbstract:
To address the problem of serious damage to the segmented roadways during the cooperative mining of the three middle sections of the Jinchuan III mine, a three-dimensional numerical model was constructed by geostatistical investigation of the damage characteristics of each segmented roadway, and a numerical calculation method was used to analyse the deformation characteristics, the extent of damage to the surrounding rock and the stress evolution characteristics of each segmented roadway during the cooperative mining. The damage mechanism of the segmental roadway was discussed. The results of the study show that under the combined effect of the synergistic mining disturbance and the original ground stress, the overall deformation and damage of the 1330 m section roadway is the most serious, followed by the 1110 m section roadway, and the 1438 m section roadway is the smallest; the deformation and damage parts of the 1438 m section roadway are mainly located in the bottom plate and the near-disturbed gang, the 1330 m section roadway is mainly located in the near-disturbed side, and the 1110 m section roadway is mainly located in the The damage in different areas of the segmental roadway is relatively consistent. The results of the study provide a theoretical basis for the maintenance and disaster prevention of the segmented roadways in the three middle sections of the three mines under collaborative mining conditions.
- 1
RESEARCH ON STRUCTURAL PARAMETERS OF FALSE ROOF UNDER THE COUPLED OPTIMIZATION OF ELASTIC MECHANICS AND NUMERICAL SIMULATIONAbstract:
The stability of the backfill false roof is very important to the safety of mining operations under false roofs and the economic benefits of mines in underground mines where the ore is weak and broken and the ground stress is high. Taking the backfill false roof constructed by the upward horizontal layered approach backfill mining method adopted in Jinfeng Gold Mine as the research object, in order to determine the optimal plan for the structural parameters of the backfill false roof, the theoretical calculation and analysis of the thin plate were used to obtain the results. Three sets of backfill false roof structural parameter optimization schemes suitable for Jinfeng Gold Mine; FLAC3D numerical simulation software was used to simulate and analyze the three backfill false roof optimization schemes respectively, and obtained the backfill during the mining process under the backfill false roof. The variation law of the stress field and the displacement field of the false roof, and finally the optimal scheme of the structural parameters of the filling body false roof is optimized. The research shows that when the thickness of the false roof of the backfill is 2.6m and the 28d uniaxial compressive strength is 2.52MPa, the simulation results are consistent with the theoretical analysis results. The research results are scientific and reasonable, and are suitable for Jinfeng Gold Mine. Use is instructive.
- 1
Experimental Study on Effect of Iron Tailings Powder on Concrete Properties in Low Clinker SystemAbstract:
Aiming at a large amount of fine tailings powder in iron ore mountain tailings pond, the influence of fine tailings powder on concrete performance is studied. C30 and C50 concrete were prepared with different proportions of iron tailings fine powder and slag powder in low cement clinker system. The working performance, mechanical properties and durability tests of concrete were carried out to study the influence of iron tailings fine powder on concrete performance. The internal structure of concrete was observed by scanning electron microscope. When the ratio of iron tailings powder to slag powder is less than 5:5, the concrete has good fluidity and high later compressive strength. The compressive strength at 360d is 44.1MPa and 73.5MPa respectively. The anti carbonization and anti chloride ion corrosion ability of the concrete is equivalent to that of the concrete mixed with slag powder alone, with more hydration products and dense microstructure.
- 1
Full Tailings Flocculation Settling Test and Parameter Optimization Research Based on Response Surface MethodologyAbstract:
In order to determine the optimal test plan for the full tailings flocculation settling test, the Danba Dulanggou Gold Mine was taken as the research object. Based on the indoor single-factor full tailings flocculation settling test, the flocculant unit consumption, tailings slurry concentration and flocculant concentration were determined. The experimental design range of the three factors, based on the response surface analysis method, designed 17 groups of experimental programs, studied the influence of the three factors on the flocculation and sedimentation effect under the interaction, and established the relationship between the three factors and the underflow concentration and sedimentation velocity. The response surface regression model optimizes the flocculation and settlement parameters of full tailings in Dulanggou Gold Mine. The research results show that the flocculant unit consumption has the greatest influence on the flocculation and sedimentation effect of tailings; the degree of influence under the interaction of the three factors is: flocculant unit consumption and tailings concentration > flocculant unit consumption and flocculant concentration > tailings Mine concentration and flocculant concentration; under the conditions of mine filling technology, the optimal parameters for flocculation and settlement of tailings in Dulanggou mining area are 30g/t flocculant consumption, 10% tailings concentration, and 0.5‰ flocculant concentration.
- 1
Mechanism of Inhibition of Coal-Pyrite by Hydrogen Peroxide and Calcium OxideAbstract:
Effective inhibition of coal-pyrite is the key to the flotation desulfurization of coal slime . In this study, the inhibition effect enhancement and action mechanism of hydrogen peroxide (H2O2) and calcium oxide (CaO) on coal-pyrite were studied by flotation test and mineral surface analysis technology. The research results show that under the optimal dosage of H2O2 and CaO, the floating rate of coal-pyrite is 15.15% and 15.45%, respectively. When CaO (2 kg/t) and H2O2 (60 kg/t) were added at the same time, the floating rate of coal-pyrite was at least 8.97%, which indicates that H2O2 can strengthen the inhibition of CaO on pyrite. The interaction of CaO with pyrite can produce a small amount of calcium-containing substances (mainly sulfate) covering the surface of pyrite, which reduces the hydrophobicity of the surface of pyrite to a certain extent. Under the combined action of H2O2 and CaO, the redox reaction on the surface of pyrite intensifies. It promotes the breaking of Fe-S bonds on the surface and the dissolution of Fe and S ions, as well as the formation and coverage of Fe-containing oxidation products(Fe2(SO4)3,Fe(OH)3,Fe2O3) and Ca-containing oxidation products (CaSO4,Ca(OH)2), which ultimately strengthen the inhibition of coal-pyrite.
- 1
Research on Coal-rock Recognition System based on Convolutional Neural Network and Semantic Segmentation Hybrid ModelAbstract:
Coal-rock identification in fully mechanized mining face is the key technology to realize intelligent unmanned mining in coal mine. At present, the research of coal-rock recognition based on image is mainly to classify and recognize coal-rock, there are few studies on the identification of coal-rock complex mixed layer interface. Therefore, this paper proposes a coal-rock information recognition edge calculation system based on convolutional neural network, which includes coal-gangue’s intelligent classification unit, coal-rock’s intelligent semantic segmentation and visual reconstruction unit. In the intelligent classification unit of coal-gangue, data enhancement module (DEM) and image saliency processing module (LC) are used for image processing. The saliency images obtained are classified and identified by VGG16 deep network model. The experimental results show that the test accuracy of this model can reach 99.07% on self-made coal-gangue data set. In the coal layer semantic segmentation and visual reconstruction unit, the Channel Attention module (CA) is embedded into Deeplab v3+ backbone network, and the Poly adaptive learning strategy is used to automatically adjust the learning rate of network training. The CA_Poly_Deeplab v3+ network was constructed for the task of coal-rock image segmentation. Compared with Deeplab v3+ benchmark network, the average intersection ratio (mIoU) of self-made coal-rock segmentation data set increased by 7.74%, achieving better interface segmentation recognition and visual reconstruction effects.
- 1
Analysis of Vibration Characteristics of Fixed-Free Riser 3D Numerical Simulation Based on Fluid-Structure InteractionAbstract:
The overall structure of the liquid level measuring device developed by Changsha Mining Research Institute is a vertical tubular structure. When working, the device is in the pulp, and the environment of the flotation cell imposes various loads on its mechanical structure. Aiming at the vibration characteristics of the device in a fluid environment, the research is carried out based on the finite element method. According to the actual environment of the liquid level detection device, a simplified three-dimensional flow model of the riser with one end fixed and the other free was established. For the simplified fluid-structure coupling system with an aspect ratio of 78.125, a shell element model and a solid element model were established respectively. Comparing the numerical simulation results of the two models, it is concluded that the shell model can be better applied to the study of the system. The shell element model was selected for modal analysis, and the first 10 modal modes and modal frequencies of the riser were obtained. The influence of different velocities of slurry on the vibration characteristics of the riser was calculated and analyzed.
- 1
Strength and mix proportion optimization of wet shotcrete under multiple factorsAbstract:
The mix proportion is the critical factor affecting the strength of wet shotcrete, and it contains a variety of factors that make the optimal proportion difficult to determine. In order to investigate the strength development law of wet shotcrete under the influence of multiple factors and to optimize the proportion, the proportioning experiments were carried out using the central composite experiment method. In the central composite experiment, the percentage of waste rock, cement content and water-cement ratio were set as affecting factors, and the compressive strength of wet shotcrete wass set as the response quantity, thus a strength regression model was constructed and strength optimization analysis was carried out. The results show that the intensity regression model constructed in this paper is highly significant with P<0.01; F>3.2, which is statistically significant. The strength of wet shotcrete increases and then decreases with the increase of waste stone proportion, and decreases with the increase of cement content and the decrease of water-cement ratio. The intensity variation pattern under the effect of multiple factors is basically the same as that under the effect of single factor. In this study, the optimum mix proportion for C25 and C30 strength classes of wet shotcrete are proposed and test to verify the reliability of the relevant mixes.
- 1
Analysis of Slurry Transportation Characteristics and Wear of Spiral Pipe Based on CFD-DEM CouplingAbstract:
In order to solve the problem of serious wear in the horizontal pipeline hydraulic conveying process of high-concentration filler slurry, the scheme of using three spiral pipe for slurry conveying is proposed.and the computational fluid dynamics-discrete unit method (CFD-DEM) is applied to conduct numerical simulation of the slurry conveying process, and the slurry conveying characteristics and pipeline wear of the spiral pipeline are explored. The results show that the wear of ordinary pipes mainly occurs at the bottom of the pipe, and the wear is mainly caused by the sliding friction of particles, while the wear in the spiral pipe is more evenly dispersed to the pipe wall. When the inlet velocity are 1.2~2.4 m/s and the average particle size of the coarse particles are 1.2~2.1 mm, the maximum and average wear depth of the spiral pipe was reduced by 17~34.6% and 72.6~87.7% respectively compared with the round pipe. Spiral pipe can ensure continuous transmission of slurry while greatly reducing horizontal pipeline wear, providing a new idea for the design of filling pipelines.
- 1
Study of Synergetic Mining Scheme of Remaining Ore Based on the Critical Caving Span TheoryAbstract:
The complex spatial-temporal distribution of goaf and the serious ground pressure appearance are the key technical problems restricting the recovery of remaining ore in the iron ore. To solve this above problem, based on the critical caving span theory, consideration of resource exploitation and hidden danger treatment, the paper raised the scheme of mined ore and goaf treatment in the iron mine, and the engineering case was analyzed. According to the complex spatial-temporal distribution characteristics of remaining ore, the remaining ore and goaf were divided into the region of A, B and C, the block scheme was raised and designed in the A region, and the pillar and rock were lasting caving in the B region. Then, the non-pillar sublevel caving was used to remaining ore in the C region, the recovery rate approximately 78% and the dilution rate approximately 25%. After that, the number simulation software was used to simulate the process and verified the feasibility of the scheme. The above study results can provide technical reference for safe and efficient mining remaining ore under hidden influence of goaf.
- 1
Study on microseismic signal characteristics about rock fracture and blasting vibrationAbstract:
In order to compare and analyze the microseismic signal characteristics of rock fracture signal and blasting vibration signal, the time-frequency and energy distribution characteristics of these two types of events at the 10303 working face of Jining No.2 Coal Mine are analyzed by using fast Fourier transform, and wavelet packet analysis. The results show that the signal amplitude of the blasting vibration signal is higher than that of the rock fracture, and the take-off amplitude of the blasting signal is higher. The main frequency of the blasting signal is high, and the frequency distribution is more scattered and complex. The main frequency of rock fracture signal is low, and the frequency is mainly distributed between 20-100Hz. The maximum energy band of the blasting vibration is greater than 20, and the signal is concentrated in high frequency band. The maximum energy band of the rock rupture signal is less than 20, and the signal is concentrated in low frequency band. Finally, a multi-parameter microseismic signal identification model is established to overcome the defects of single index. This research can provide some reference for the identification of mine microseismic signals.
- 1
Multipurpose Utilization of Tailing Resources from Silver Dressing and Stockpiling in Shanxi ProvinceAbstract:
The tailings pond of a silver ore dressing plant is used to store silver tailings,in which the gold content of the valuable metal element is 0.31 g/t,and the silver content is 108.21 g/t. In order to comprehensively recover valuable metals in tailings,realize its comprehensive utilization,improve mine service life and achieve the goal of sustainable development,the beneficiation test research on the comprehensive recovery of gold and silver from the storing tailings in the tailings pond was carried out. The result showed that adopting the flotation process of asynchronous roughing- concentrate regrinding and selecting,in the condition of grinding fineness being 60% of -0.074 mm content,using butyl xanthate and butylammonium aerofloat (dosage ratio 2:1) as collectors,copper sulfate as activator,performing three-stage asynchronous roughing; then regrinding the coarse concentrate to -0.045 mm content being 70% and selecting, in the end the silver concentrate of gold and silver contents being 9.92 and 3 318.91 g/t,the recovery being 87.05% and 93.85% could be attained. The test not only realized the comprehensive recovery of precious metal gold and silver,but also provided a reliable technical basis for the comprehensive recovery of gold and silver from mine tailings.
- 1
Application of Eco-efficiency Assessment Model in Gold MineAbstract:
To calculate the ecological benefits of ecological mine construction, and ecological benefit evaluation index system and an ecological benefit model is constructed, and the connotation and ecological benefit composition of ecological mine construction are studied. Based on a comprehensive analysis of the current situation of ecological mine construction at home and abroad, the connotation of ecological mine construction with the harmonious coexistence of government, enterprise, and land as the core is given, and around the specific contents of ecological benefits, an evaluation index system of ecological benefits including essential safety, efficient utilization of resources, energy-saving and emission reduction, community harmony and ecological restoration is constructed, which comprehensively covers humanities, environment, resources, and society, and an ecological benefit The quantitative model of indicators can quantitatively evaluate the construction effect of ecological mines in monetary terms. In this study, the ecological benefits of a gold mine are calculated, and the calculation results show that the ecological benefits of ecological mine construction are 357,438,200 yuan/a, of which the essential safety benefits are 26,963,000 yuan/a, the benefits of efficient utilization of resources are 26,343,000 yuan/a, the benefits of energy-saving and emission reduction are 10,579,200 yuan/a, the benefits of community harmony are 292,484,000 yuan/a, and the benefits of ecological restoration are 106.6 million yuan/a. From the perspective of mining enterprises, the benefit of essential safety accounts for the largest proportion. From the perspective of society, community harmony brings great economic benefits to society. The research results show that the ecological benefit evaluation relatively objectively reflects the construction effect of ecological mines, and to a certain extent, it can provide a reference for the construction of ecological mines in the same type of mines.
- 1
EXPERIMENTAL STUDY ON BENEFICIATION OFA FLUORITE ORE IN HENANAbstract:
According to the analysis of fluorite ore in henan province, the valuable elements are fluorite, molybdenum and silver, due to molybdenum and silver have no recovery value,So only fluorite among them is recovered.Through the process test and the test of different parameter conditions, and choose our self-made high-efficiency collector XYS-F1,it is determined that the fluorite ore has passed the test process of " one stage grinding +one roughing one sweeping and five refining selection of -0.075mm accounts for 65%, and the fluorite concentrate grade is obtained 98.03%, the recovery rate is 96.68%; the tailings grade is 3.65%, and the recovery rate is 3.32%. The fluorite concentrate has reached the grade requirements of fluorite concentrate FC-98 (YB/T5217-2005).
- 1
Study on stable transportation technology of pressure regulating full pipe inhigh well deep paste filling pipelineAbstract:
Aiming at the problem of accelerated wear and failure of the inner wall of the pipeline caused by the non-full state of the filling pipeline due to the large drop of the vertical pipeline in the filling system of the high well depth filling system, the influencing factors of the non-full height of the vertical pipeline are calculated and analyzed, and the formation mechanism of the non-full pipe of the vertical pipeline filled with high well depth is studied. Taking an iron mine in Anhui as the research object, the ratio optimization of full tailings filling slurry and the pressure monitoring of underground filling pipeline were carried out, and on this basis, the flow rate and pressure control technology of filling slurry were proposed. The results show that : 1 ) when the static pressure head provided by vertical height difference is greater than the required resistance along the pipeline, the acceleration of paste slurry leads to negative pressure in the pipeline, resulting in air column in the pipeline, and the further increase of flow velocity aggravates the wear and failure of the pipeline ; 2 ) For mines that have been put into production and are difficult to adjust the pipeline system, the full pipe rate can be improved by slurry modification, increasing slurry resistance and changing vertical pipe diameter ; 3 ) The resistance along the route decreases first and then increases with the conveying flow, and with the increase of the flow, the lowest point appears in the range of 250 – 260 m3 / h, and it is suggested that the conveying flow range of the ore slurry is about 250 – 260 m3 / h ; 4 ) The smaller the diameter of the variable diameter pipe is, the higher the filling rate of the vertical pipe is. The length of the variable diameter pipe is proportional to the filling rate. When the diameter is 30 mm and the length is 2 m, the filling rate of the vertical pipe reaches 87.66 %. The change of the installation position of the variable diameter pipeline in the horizontal pipeline has little effect on the full pipe rate of the whole vertical pipe.
- 1
Optimization of Stope Parameters with Different Depths Based on CRITIC-TOPSIS Comprehensive EvaluationAbstract:
After long-term continuous mining, the mining level of an iron mine is gradually deepened. In order to further optimize the structural parameters of stopes at different depths, FLAC3D numerical simulation software is used to analyze the maximum vertical displacement and maximum tensile stress of stope roof under different mining levels and different room spans. Based on the CRITIC-TOPSIS comprehensive evaluation model, different design schemes are comprehensively evaluated. The results show that mining level and stope span are the key factors affecting stope stability. Under the same mining level, the maximum vertical displacement and tensile stress of stope roof increase with the decrease of backfill strength and the increase of stope span, and the strength of backfill is the dominant factor. According to the analysis of the comprehensive paste progress evaluation model, the optimal chamber spans at -470 m, -530 m and -560 m levels are 22 m, 20 m and 18 m, respectively, indicating that the larger the stope burial depth is, the smaller the chamber span is. The research results can provide a basis for the design of structural parameters of deep stope in the iron mine
- 1
Prediction of Displacement and Deformation of Laoyingzui Slope Based on GM(1, 1) ModelAbstract:
The displacement and deformation of the slope reflects the deformation and instability state of the slope, so the effective prediction of the slope displacement can be used as the basis for disaster avoidance and disaster prevention, thereby reducing the economic losses caused by geological disasters. Taking the monitoring data of the slope position of the Laoyingzui in the Huangshan limestone mine in Sichuan as a sample, a prediction model of the slope displacement of the Laoyingzui is established based on the GM (1,1) model. The research shows that the accuracy of the initial prediction model is low. Through residual correction, the model level is upgraded from level IV to level II and above, and the variation trend of the obtained displacement pre-side value and real side value is more similar; Through the model optimization research, it is concluded that the optimal sequence length for model establishment is 20. The above research results can provide a certain scientific basis for judging the deformation state of the slope and avoiding disasters and reducing losses.
- 1
Research on the design and parameter optimization of belt conveyor roadway support for soft-break large sections at high altitudeAbstract:
In order to study the difficult problem of supporting belt conveyor roadways at high altitude with soft breaks and large cross sections, the main conveyor belt roadway of the Jurong copper mine in Tibet was used as the research object. The design of the roadway support scheme, and the use of numerical simulation software, the establishment of numerical models, the support process of the roadway stress distribution, displacement evolution, plastic zone distribution to study the belt transport roadway support scheme and parameter preferences. The results show that the design of the support is ‘over-support’ + ‘long anchor cable - short anchor rod - hook and loop net combined support’ + ‘steel frame - shotcrete support’ combined support; Preferred support parameters are 10m long anchor cables, 1.5m anchor cable row spacing and a lining thickness of 20cm, which has a maximum displacement of 6.0mm; And the site monitoring results show that it is able to meet the safety requirements for the transport of ore in the belt haulage lane in the mine area.
- 1
Test of thickening sedimentation of unclassified tailings under the action of ultrasonic hornAbstract:
In order to explore the promoting effect of ultrasonic wave generated by ultrasonic concentrator on the thickening of full tail mortar, the self-made sand bin model is used to conduct the physical test of dense settlement of full tail mortar. Based on the control variable method, the effects of ultrasonic wave applied at different times of full tail sand settlement and ultrasonic wave with different power on its dense settlement effect are explored. The results show that the sound intensity attenuation law of ultrasonic in clean water and full tail mortar is similar, and the distance can be divided into "continuous attenuation stage" and "fluctuation attenuation stage". In the "continuous attenuation stage", the relationship between the sound intensity of ultrasonic in clean water and the power is inversely proportional, but it is directly proportional in full tail mortar; In the "wave attenuation stage", the sound intensity values in both cases increase with the increase of power. In addition, the sound intensity attenuation rate in the two cases is directly proportional to the power in the "continuous attenuation stage" and inversely proportional to the power in the "fluctuation attenuation stage". On the whole, the sound intensity attenuation rate of both decreases with the increase of power. In actual production, it is not the application of ultrasonic wave that can improve the dense settlement effect of full tail mortar. The power of ultrasonic wave and the application time in the settlement process of full tail mortar are influencing factors, which will even have opposite effect on the thickening sedimentation of full tail mortar.
- 1
Preparation of a Complex Conditioner Applied to Low-Grade Phosphate Rock during Calcination-Leaching and Acid Activation ProcessAbstract:
To prepare a complex conditioner, a new technique was applied that included calcination, leaching, and acid activation. The low-grade phosphate rock used in this study mainly consisted of Ca5(PO4)3F, and CaMg(CO3)2. Due to the lower P2O5 content and higher impurities, it is important to carry out highly efficient applications of low-grade phosphate rocks. The CaMg(CO3)2 decomposed into CaO and MgO after calcination. Then, the calcined samples were added to the NH4NO3 solution for leaching. Ca and Mg were transferred to the solution. After filtration, high-grade phosphate rocks were obtained. Ca(NO3)2 and Mg(NO3)2 and the remaining NH4NO3 formed water fertilizer after neutralization. NH3 was absorbed by the dilute nitric acid, which enabled the recycling of the ammonium nitrate. The P2O5 content was increased from 10.18% to about 29.04% via calcination-leaching. In acid activation process, the refractory phosphorus was activated via reaction between the phosphate rocks and urea sulfate, and the phosphorus activation rate of the complex conditioner was 96.2%. After the reaction and drying, the products included CaSO4·4CO(NH2)2, CaSO4·0.5H2O, CaHPO4, Ca(H2PO4)2, and (NH4)2SO4. Finally, the soil conditioner was obtained by adding KCl to the products. The calcination, leaching, and acid activation provide a new way for the utilization of utilizing low-grade phosphate rocks.
- 1
ANALYSIS OF EARLY WARNING PARAMETERS OF GROUND PRESSURE DISASTER IN KUANGSHANCHANG PLANT BASED ON MICROSEISMIC MONITORINGAbstract:
In order to study the multi parameter early warning technology in the monitoring range of kuangshanchang, the early warning threshold suitable for the mine was summarized. This paper is based on the mining that a 30 channel microseismic monitoring system was established between 1764m level and 1274m level in May 2018. Firstly, the manual blasting test is used to correct the system setting parameters to ensure the normal operation of the microseismic monitoring system.Then the screening and processing of the collected data, an effective microseismic event database is constructed. The time series, spatial distribution and evolution, quantitative seismological parameters of microseismic events are analyzed.The results show that: q-time > 1 in the high order concentration area, q-space in low value zone of epicenter concentration, q-space ≤ 100, seismological parameter B ≤ 0.27 β N high value area β N ≥ 5.0 and η High value area η It is determined that the threshold value of earthquake monitoring system of Qilinchang is ≥ 1.05, and the target of monitoring and warning of ground pressure disaster in Qilinchang can be achieved.
- 1
Influence of Curing Temperature on the Strength of Quaternary Solid Waste Cementitious MaterialsAbstract:
The solid waste cementitious material was prepared by refining slag-steel slag-desulfurized gypsum-slag, and its strength development law and micro-consolidation mechanism at different curing temperatures were explored, and the quaternary solid waste cementitious material was characterized by XRD, thermogravimetric and SEM experiments Hydration mechanism under low temperature curing. Experiments show that the curing temperature has a great influence on the strength growth of the cementitious material, and the strength is positively correlated with the curing temperature. This system is driven by the generation of hydration products AFt and C-S-H gel at low temperature, and the amount of AFt and C-S-H gel generated is proportional to the curing temperature. Under low temperature curing conditions, hydrolysis in the solid waste raw material system is inhibited, and the hydration process is also affected by low temperature. The addition of refining slag has a significant contribution to the strength development of the whole system under low temperature curing.
- 1
Similarity simulation study on mine pressure behavior of intelligent mining face with large dip AngleAbstract:
The study of pressure appearance and intelligence before intelligent mining is very important for intelligent mining of large dip face. Taking the 1031 working face of Yangliu Coal Mine as the background, the intelligent mining conditions of 1031 working face were studied by "Intelligent mining working face Classification, classification technical conditions and Evaluation Index System", and the advanced abutment pressure and overburden migration law were analyzed through similar simulation test. The results show that the comprehensive evaluation result of working face classification is 79.8 points, and the comprehensive evaluation of working face condition is class ⅱ. Intelligent mining can be implemented. The shape of overburden subsidence is asymmetrical arch, and the displacement of maximum subsidence is 1.72 m in the horizontal direction and 3.24 m in the vertical direction. During mining, the stress peak range is 18~23 MPa, and when the working face is pushed directly above the measuring point, the stress is 6~8 MPa. The field measurement shows that the normal and safe mining of the working face can be realized. The research conclusion can not only provide a theoretical reference basis for intelligent mining of 1031 large dip Angle working face, but also have a certain reference significance for mining of working face under the same geological conditions.
- 1
Research on the Role,Consumption and Demand of Ferrous Metal Minerals in Emerging Sectors of Strategic ImportanceAbstract:
Emerging sectors of strategic importance are the industry with critical leading role and growth potential for the long-term development of economy and society, and ferrous metal minerals are a kind of key raw materials to support the development of emerging sectors of strategic importance. Therefore, it is very important to clarify the role, consumption status and demand of ferrous metal minerals in emerging sectors of strategic importance. Based on industrial development and current situation of mineral resources, this paper analyzes the consumption status of ferrous metal minerals in emerging sectors of strategic importance by using the combination of " the industrial chain" and " reverse the industrial chain", and then predicts the demand of ferrous metal minerals in emerging sectors of strategic importance during the -year plan" by using ARIMA model. The results are shown that: (1) in 2020, ferrous metal minerals was mainly applied four primary industries such as new generation information technology industry, high-end equipment manufacturing industry, new material industry and new energy new materials, involving more than 100 kinds of important products. Among them, the new material industry was the most applied field, and the consumption proportion was as high as 62.84%; (2) In 2020, the consumption of ferrous metal minerals in emerging sectors of strategic importance was 17.75 million tons (metal), accounting for 1.7% of the total consumption. The consumptions of iron, manganese, chromium, titanium and vanadium were 14.63 million tons, 1.64 million tons, 1.35 million tons, 130 thousand tons and vanadium 3000 tons, respectively; (3) During the "14th five-year plan" period, the demand for ferrous metals in emerging sectors of strategic importance will keep growth. In 2025, the total demand will reach 21.05 million tons, accounting for 2% of the total consumption. The demands of iron, manganese, chromium, titanium and vanadium will be 16.21 million tons, 2.2 million tons, 2.3 million tons, 290 thousand tons and 6000 tons, respectively.
- 1
Study on downward continuous mining technology of near-surface ore body in grassland areaAbstract:
Abstract: In order to research the mining scheme of near-surface ore body in grassland area, reduce the damage to grassland environment as much as possible, and at the same time,get the goal that ore body can be mined safely and efficiently. Taking the near-surface orebody of Wulan Mine as the research object, study the different mining schemes in the upper and lower ming levels, and using numerically analyzing method to study the influence of mining on the surface environment in the mining process ,get the influence of surface displacement . The results show that: High-end wall open stoping with delayed filling method is used in upper levels, long hole open stoping with delayed filling method is used in lower levels,backfilling materials used to fill the goaf, realize the downward continuous mining of the ore bodies ,control the surface subsidence effectively, protect grassland environment requirements , Realize fast and low cost mining of near surface ore body. The research and field application of mining technology of near-surface ore body in grassland area can provide reference for green and efficient mining technology of similar ore body in limited mining environment.
- 1
Study on Promoting Mechanism of Surfactant in Hongxinghe Slime FlotationAbstract:
The surface properties of refractory hongxinghe coal were systematically analyzed by industrial analysis, elemental analysis, XRD, IR and XPS. The flotation test results of Hongxinghe coal were analyzed by mixing agents of different surfactants (CTAB, Span80) and diesel oil. It was found that under the same flotation agent system, the flotation effect of CTAB+Span80+diesel oil was better than that of its combination.CTAB+Span80+diesel compound can significantly improve cleaned coal yield and combustible body recovery.Through the comparison of contact Angle and wetting heat before and after the action of different compound agents, it is found that CTAB+Span80+diesel compound agent can more easily act on the surface of Hongxinghe coal, reduce the content of hydrophilic functional groups on the coal surface, improve the surface hydrophobicity, so as to strengthen the flotation effect.
- 1
Present Situation and Key problem of Metal Mineral Resources Exploitation in High Altitude Cold Region of ChinaAbstract:
The high-altitude cold area in China is widely distributed and rich in metal mineral resources, which is an important strategic resource reserve area of the nation. However, the mining process in the western high-altitude cold area is faced with many special and complex mining environment, including high cold with low pressure and low oxygen climate, complex plateau geological structure, fragile ecosystem and so on. Based on high altitude cold regions in our country mineral resource endowment, against freeze-thaw rock and soil mechanics, man-machine efficacy, ventilation and safety and the ecological environment four aspects briefly expounds the problem that the high-altitude cold metal mineral resources exploitation. Intelligent mining and green path of development of metal mineral resources, proposes the key scientific problems of mineral resources exploitation and the technical content are point out. It provides some reference for the exploitation of metal mineral resources in high-altitude cold area of western China.
- 1
Optimization of second step stope structure parameters under bad backfill conditionAbstract:
The 25# ore body of Hecheng Mining In Wuhu, Anhui adopts the sublevel drilling stage open stoping with subsequent filling mining method,the stoping progress in the second step lags behind seriously because of the filling quality problem in the first step.In order to ensure the safety and high efficiency of stope under the condition of bad backfill,FLAC3D software and Rhino software were used to simulate six different stope structural parameters.The optimal stope structural parameters are as follows:?When the strength of filling body on both sides of the stope in the second step is: one side is greater than 2MPa, and the other side is less than 2MPa and greater than 1MPa, the thickness of protective wall is 3m, the thickness of top column is 5m, and the thickness of inter-column is 5m.When the strength of the filling body on both sides of the stope is less than 1MPa, the thickness of the protective wall is 3m, the thickness of the top column is 6m and the thickness of the inter-column is 4m. The research results can be used as a reference for the selection of stope stope recovery scheme under the condition of the same type of mine with bad filling body.
- 1
Design of mining “Three-under” pressure coal and optimization of numerical simulation at Baiyuan MineAbstract:
Banyan Coal Mine located at Pingxiang city is a resource-exhausted area. “Three-under” pressure coal induces a lot of waste of coal resources. Based on the geological conditions at Baiyuan Coal Mine, the present study adopted a similar material simulation method to perform the disturbance analysis of rock strata by scaling down the rock strata in the coal mine (Geometric similarity ratio CL=1：200，Ratio of cubage and weight C=1：1.6). The UDEC numerical simulation is conducted to analyze the disturbance of rock strata (The model is developed along the strike direction, coal seam thickness is 3.5m, mining depth is 600m). A comparative study is conducted to understand the impact of the strip mining method and the longwall mining method on overlying rock strata and surface deformation. The surface movement and deformation indicators such as subsidence, tilt, horizontal movement and horizontal deformation are compared and analyzed in 4 different mining cases. The simulation results reveal that the strip mining with the 1.0 ratio value of mining of remaining has less impact on overlying rock strata than the longwall mining method. In addition, the higher ratio of mining and remaining in the strip mining corresponds to the more significant influence of coal mining. Therefore, considering geological conditions, mining technical difficulty and socioeconomic benefits, combined with theoretical analysis and on-site monitoring methods, the longwall mining method is recommended because the surface of Baiyuan Mine has large areas of brick-concrete structures. When protecting buildings or high-rise buildings, it is recommended to use the strip method for coal mining, and keep the protective coal pillars or use the filling method for mining; set up prohibited mining areas in key areas such as railways to ensure green and safe mining in the mining area.
- 1
Effect of phosphogypsum on cement-based filling slurry and its hydration mechanismAbstract:
To improve the comprehensive performance of mine filling body, cement-based composite filling slurry was prepared by cement, tailings and phosphogypsum. The influence of phosphogypsum and tailings content on slump, shrinkage, strength, and durability was analyzed. The hydration mechanism of material filling slurry was studied according to the microscopic experiment and mineral composition results. The results show that using phosphogypsum to replace part of cement is beneficial to improve the workability index of tailings backfill and reduce the drying shrinkage rate. When the replacement ratio of phosphogypsum is 15%, the workability, strength and durability of the full tailings filling slurry are significantly improved. The chemical activity of phosphogypsum can promote the secondary hydration of the cementitious material and increase the compactness of the filling slurry. This study has important reference function for the preparation of high performance full tailing composite filling body.
- 1
Study on the Separation of Tin-tungsten mixed Concentrate in Inner MongoliaAbstract:
In order to solve the problem that the content of arsenic in a tin-tungsten mixed concentrate in Inner Mongolia is seriously exceeding the standard, an experimental study on the efficient separation of tin, tungsten and arsenic was carried out on the concentrate. Using the combined flotation-magnetic separation process, tin concentrate with Sn grade of 53.83% and recovery rate of 98.97% and tungsten concentrate with WO3 grade of 63.96% and recovery rate of 87.70% can be obtained. At the same time, the by-product arsenic concentrate of the separation process contains 66.84% arsenic, and the recovery rate is 99.09%. This process not only obtains qualified tungsten concentrate and tin concentrate, but also comprehensively recovers the harmful element arsenic, which not only realizes the efficient utilization of tungsten and tin resources, but also reduces the harm of harmful element As to the environment.
- 1
Inversion of tectonic stress field with faults based on PSO-SVR modelAbstract:
In order to obtain the initial in-situ stress field of fault structure area and improve the accuracy of stress inversion, an initial in-situ stress field inversion method based on particle swarm optimization and support vector regression (PSO-SVR) is proposed to inverse the initial in-situ stress field of fault structure area in Shihao Coal Mine and analyze the regional in-situ stress field. The results show that the error between the stress inversion value of each measuring point and the measured value is small, the inversion accuracy is high, the stress field distribution in the fault structure area is reasonable, and the inversion results are effective and reliable. The in-situ stress distribution in the fault structure area is mainly affected by the formation lithology and tectonic action. The in-situ stress value changes significantly around the fault, and the in-situ stress difference inside and outside the fault is large. Through the verification of actual working conditions, it is proved that PSO-SVR model has good applicability and feasibility in the inversion research of in-situ stress field in fault structure area, and can provide reasonable and reliable initial in-situ stress field data and effective theoretical basis for engineering design and construction in structure area.
- 1
Study on Permeability of Single Fracture in the Triaxially Stressed Anthracite Subjected to Injection of Superheated SteamAbstract:
In situ heat injection to enhance coalbed methane mining is one of the effective ways of efficient coalbed methane mining. In order to study the seepage characteristics of coalbed fractures in the process of in-situ heat injection mining of coalbed methane, the variation characteristics of single fracture permeability of anthracite before and after high temperature superheated steam injection under the stress conditions of 200m and 400m buried depth were studied by using the self-developed heat injection high temperature and high pressure rock triaxial experimental system, It is found that the single fracture permeability of anthracite increases after 12 hours heat injection. The increase range is related to the magnitude of triaxial stress, and the greater the pressure, the smaller the increase range. After heat injection cooling, the fracture permeability is affected by triaxial stress compression, and the permeability decreases slightly, but it is still higher than that before heat injection; By comparing the changes of micro cracks on the surface of single crack before and after heat injection, it is found that after injecting high-temperature superheated steam, a large number of micro cracks are added on the crack surface, the existing micro cracks further expand and the opening increases, which effectively increases the fracture conductivity.
- 1
Preparation and Adsorption of Pb(Ⅱ) Based on Magnetic Adsorption Materials for Coal-based KaoliniteAbstract:
For the development of coal gangue and other solid waste resource utilization technology, the coal-based kaolinite as raw material, a series of coal-based kaolinite / Fe3O4 magnetic composite materials were prepared through coprecipitation, surveying the adsorption of Pb(Ⅱ) in water, and by XRD, SEM, BET and other methods for the chemical and physical properties of adsorption materials were analyzed. The results show that the C-F-1 composite has the best adsorption effect for Pb (Ⅱ) when the mass ratio of coal-based kaolinite to FeSO4.7H2O is 1:1 and the mole ratio of Fe (Ⅲ) to Fe(Ⅱ)is 2:1.And that the maximum adsorption capacity was 201.69mg/g when the adsorption temperature was 25℃, the adsorption dose was 3g/L, the initial concentration of Pb (Ⅱ) was 700mg/L, the initial pH value was 6, and the adsorption time was 90min, which was better than that reported in most literatures. The characterization results show that C-F-1 is approximately spherical in shape, 10-20μm in diameter, and about 30nm Fe3O4 particles are loaded on the coal-based kaolinite lamellar. The surface is rough and loose, and the specific surface area is 2.3 times that of the coal-based kaolinite. The Zeta potential value is negative, and its absolute potential value is higher than that of the coal-based kaolinite and Fe3O4. In addition, the thermodynamic and kinetic results of adsorption show that the adsorption of Pb(Ⅱ) by C-F-1 conforms to the quasi-second-order kinetic model, and the chemical adsorption is the main method. The adsorption isotherm conforms to Langmuir model and is monolayer adsorption. The adsorption of Pb(Ⅱ) by C-F-1 is endothermic and spontaneous. C-F-1 prepared from coal-based kaolinite has the advantages of cheap materials, good adsorption performance, easy separation and recovery, and has potential industrial application value.
- 1
Study on pressure relief control and recovery rate of initial mining and initial caving in extra thick coal seam with hard roofAbstract:
In view of the phenomenon of strong pressure and low recovery rate caused by large overhanging roof during the initial mining of working face, taking tangjiahui Coal Mine hard thick roof coal seam as the background, Numerical simulation, theoretical analysis and field measurement are used to comprehensively study the collapse law of overburden strata on working face, the evolution characteristics of surrounding rock stress and displacement, and the failure law of top coal affected by mining under the pressure relief technology of cutting hole and top coal. flac3d numerical simulation found that using cut unloading technology can be cut off at the coal face of basic roof and cut wall stress transfer, reduce the advance abutment pressure peak value, to speed up the sinking overburden rotary instability, make roof caving more fully, at the same time increase the level of working face in front of the top-coal displacement, top-coal get a higher degree of damage. Theoretical analysis shows that the pressure relief technology of cutting the top at the beginning makes the basic roof transform from fixed support beam to simply supported beam. After cutting the top of the working face, the roof of the goaf can avoid hanging in a large area, which makes the roof collapse rapidly, and has the effect of optimizing the stress environment of the working face. The field measurement shows that the application of this technology can solve the problem of strong ore pressure appearing in hard and thick coal seam face, guarantee the safety of working face mining, make the fully mechanized caving mining can draw coal quickly, speed up the coal recovery efficiency, and greatly improve the economic benefit of working face.
- 1
Determination of Roof Support Strength of Working Face in Extra Thick Coal Seam Under GoafAbstract:
Aiming at the problem of frame pressing accident caused by excessive roof subsidence in the roof control area, taking the large mining height fully mechanized top coal caving mining of extra thick coal seam under the goaf of Huaye coal mine in Linxian County, Shanxi Province as the engineering background, 3DEC discrete element numerical simulation software is used to analyze the pressure law of the roof in the roof control area of the working face of extra thick coal seam under the goaf under different support strength, The support strength of the hydraulic support to the roof of the working face is studied. The results show that the compressive strength of the working face changes from high to low, high to low, the roof subsidence in the roof control area decreases exponentially with the increase of support strength, and the exponential attenuation equation is fitted, the safety value of the maximum roof subsidence of the working face is 45cm, and the corresponding support strength should be 1.52mpa, which can meet the roof control requirements. The research results provide a certain theoretical guiding significance for the selection of hydraulic support under similar conditions.
- 1
Strength development law and proportion optimization of mixed aggregate backfillAbstract:
The strength of mixed aggregate backfill is affected by many factors such as the ratio of mixed aggregate, the concentration of filling slurry and the cement content. In order to explore the influence of different factors on the strength of backfill and determine the optimal mix proportion, RSM-BBD method was used to carry out the mix proportion experiment of mixed aggregate. Taking the proportion of river sand, slurry concentration and cement content as the influencing factors and the strength values of backfill at 7d, 14d and 28d as the response, the strength regression model of backfill at the corresponding curing age is constructed and analyzed experimentally. The results show that the intensity regression model constructed in this paper has significant statistical significance (P < 0.01, R2 > 0.95). With the increase of the proportion of river sand, the stacking compactness of mixed aggregate first increases and then decreases, and the strength of filling body also shows the same development trend. Under the influence of many factors, the greater the proportion of river sand is, the smaller the slurry concentration is, the lower the strength of filling body is; The smaller the proportion of river sand and the greater the cement content, the higher the strength of the filling body; The strength of backfill increases with the increase of cement content and slurry concentration.
- 1
Experimental Research on Lifting Performance about Solid with Slurry Air Lift Pump used in MineAbstract:
In order to explore the relations between the efficiency and various input parameters of slurry air lift pump used in mine,it analyzes the enhancement mechanism of solid particle in the lifting pipe that bases on fluidics and static pressure, there are factors which improves performance on air lift system include air inflow and apparent gas velocity. The results show that the changes of air inflow effect discharge amount of solid,then flow pattern transformed due to it. Further study the relationship between the slurry concentration and the apparent gas velocity, the concentration change has extremely obvious fluctuation characteristics, and the velocity that is too high or too low reduces the performance of the air lift system. The study provides guidance for engineering application of minerals mining and slurry carrying.
- 1
Formula Optimization of Limestone Dust SuppressantBased on Response Surface MethodologyAbstract:
It is more targeted to control the limestone dust, and to reduce the degree of its harm.Sodium dodecyl sulfonate, soluble starch and carboxymethyl cellulose were used to prepare limestone dust suppressants. To obtain the group distribution ratio for the best suppression effect, response surface regression models for table drying time, viscosity and pH were established and analyzed for variance, confidence and surface plots.The results show that there is interaction between soluble starch and carboxymethyl cellulose which had significant effects on table surface drying time and viscosity, sodium dodecyl sulfate and soluble starch, sodium dodecyl sulfate and carboxymethyl cellulose, soluble starch and carboxymethyl celluloseplays a leading role in pH value. The optimal formula of dust depression are: 0.178% sodium dodecyl sulfate, 0.057% soluble starch and 0.523% carboxymethyl cellulose, and the performance index of dust suppressant under these conditions was 6.142 min, 500 mPa.s viscosity and pH 7.
- 1
Vibration -Noise Analysis of Idler Group for Tubular Belt ConveyorAbstract:
In order to solve the problem of vibration and noise of tubular belt conveyor, a method of vibration-noise analysis of idler group based on finite element and boundary element theory is proposed. Three contact conditions: single roll contact, double roll contact and three roll contact between idler group and pipe belt were analyzed. The measured force spectrum of idlers was taken as the excitation source, and the SPL spectrums of a single idler under three conditions were obtained, combined with roller finite element boundary element mixed sound field analysis model. The sound pressure levels of each frequency band were further extracted. The total sound pressure levels of idlers were obtained by means of sound pressure level superposition. Compared with the simulation results, the reliability of the simulation method was verified.
- 1
Predicting Fatigue Life on Canopy of Mine Hydraulic Support Based on DT-LSTMAbstract:
Hydraulic support is the key support and caving equipment for fully mechanized mining and fully mechanized caving mining intelligent working face. Aiming at the problems of equipment health assessment and failure maintenance in the underground environment, and difficulty in predicting the fatigue life of hydraulic supports, based on digital twin technology and Long Short-Term Memory (LSTM) cyclic neural network, a method of fatigue monitoring and life prediction of the top beam of the mine hydraulic support is proposed. According to the structure and working principle of the top beam of the hydraulic support in the mine, the method firstly uses the finite element method to establish a simulation model of the hydraulic support system. and uses ANSYS finite element analysis to obtain the relevant data set of the state parameters and fatigue life value of the top beam of the hydraulic support; Then use ANSYS Twin Builder to build a high-confidence digital twin verification model, and further verify and optimize the finite element simulation analysis model according to the real boundary conditions such as the yield strength of the top beam of the mine hydraulic support and the constitutive relationship; Then trains the training set through the LSTM neural network And use the test set to test to determine the prediction model of the life of the top beam of the hydraulic support, so as to realize the accurate prediction of the fatigue life of the top beam of the mine hydraulic support. Finally, the validity and superiority of the prediction model are verified by experiments. he experimental results show that, compared with the other three prediction methods, the prediction method based on LSTM neural network has the best perfor-mance, and the average error between the predicted fatigue life and the actual value is only 1.8%,which provides new ideas for the prediction and management of the fatigue life of the top beam of the hydraulic support.
- 1
Experimental Study on Mechanical Properties of Glass Fiber Reinforced Cement-based Tailing FillingAbstract:
To address the problems of low strength and poor stability of a gold mine filler in Yantai, Shandong Province, industrial solid wastes such as blast furnace slag, steel slag and desulfurization gypsum were selected to prepare cementitious materials, and glass fiber was added as reinforcing material to improve the mechanical properties of the filler. First, the physical and chemical properties of the filling materials were analyzed, and then orthogonal tests were conducted to investigate the effects of fiber dosing, fiber length and steel slag dosing on the compressive strength, flexural strength and splitting tensile strength of cement-based tailing sand cementitious filling. The results show that: with the increase of fiber dosing, the mechanical properties of the filling body show a trend of increasing first and then decreasing, when the fiber dosing is 0.5%, the compressive strength and tensile strength of the filling body take the maximum value, when the fiber dosing is 0.3%, the fracture strength of the filling body has the best improvement effect; with the increase of fiber length, the fracture strength and tensile strength of the filling body gradually increase, the compressive strength of the filling body first increases and then decreases. The compressive strength of the filler first increases and then decreases, and the compressive strength takes the maximum value when the fiber length is 6 mm. The appropriate amount of fibers mixed into the filler makes up for the internal structural defects, inhibits the crack expansion, increases the dense density, and makes the mechanical properties of the filler rise, but the excessive fibers entangle with each other to form the stress concentration zone, which reduces the mechanical properties of the filler. The mechanical properties of the filler are optimal when the dosing of steel slag is 10%, and if the dosing of steel slag continues to increase, the generation of the hydration products calcium alumina, C-S(A)-H gel and Ca(OH)2 used to support the macroscopic strength of the filler in the cementation system decreases, and the filler specimens can hardly resist large loads, and the mechanical properties of the filler keep decreasing.
- 1
Experimental Study on High Concentration Cemented Filling Materialin a MineAbstract:
In order to more safe and efficient mining and reduce filling cost in a metal mine, the original waste rock filling mining method was replaced by full tailings cemented filling mining method. Through the experimental study on the basic physical and chemical parameters, particle size analysis, and slump of the whole tailings in its concentrator, the L-tube flow tests of the whole tailings filling slurry with different mass concentrations were carried out. According to the test results, the pipeline transportation resistance of full tailings filling slurry under different mass concentrations, different flow rates and different pipeline diameters is calculated. The key influencing factors of pipeline transportation resistance are obtained, and the filling double line that can realize self-flow transportation of filling slurry pipeline is further obtained. The results show that when the filling slurry concentration is 70 % – 76 %, the slump is above 28 cm, and the fluidity is good. The key influencing factors of pipeline transportation resistance are filling slurry concentration and pipeline diameter. The greater the filling slurry concentration and the smaller the pipeline diameter, the greater the pipeline transportation resistance. In a polymetallic mine, the slurry concentration of full tailings filling is 70 % -76 %, the diameter of the pipeline is 150 mm, and the filling flow rate is 80 m3 / h. The fluidity and transportation performance are the best, and the filling multiple line that can realize the smooth self-flow transportation is 6.71-11.13. The test results can provide technical support for the construction of cemented tailings filling system in a metal mine.
- 1
Simulation Analysis of Seepage Mechanism of Steel Gauzeunder Fine-grained Tailing SandAbstract:
The progress of beneficiation process has made the tailing sand become finer and finer, which causes traditional geotextiles become more prone to clog. The engineering has proved that that geotextiles with large pore size like steel gauze perform better in the face of fine-grained tailings, but little research has been done on their filter mechanism. In this paper, the filter mechanism of steel gauze is demonstrated at the fine level by discrete element method (DEM). The simulation results show that during the seepage process, the steel gauze allows the fine particles to pass through, and promote the formation of a stable and loose arch-like structure in coarse-grained soil skeleton, which improves the permeability coefficient of the tail sands and enhances the seepage efficiency. Increasing the head in the seepage process within an appropriately range will only accelerate the formation process of the filter arch and will not destroy the arch structure which has already formed. The application of steel gauze helps to accelerate the drainage of fine-grained tailings dams, and will also mitigate the effects of physical clogging.
- 1
Investigation of the interface properties of Oily Bubbles in Low-Rank Coal Flotation ProcessAbstract:
Since the surfaces of low-rank coal is rich in oxygen functional groups, it is easy to form hydrogen bonds with water molecules in the flotation solution. So, its surface is covered by a hydration film and, therefore, the mass yield of low-rank coal flotation is low with large collector consumption, making it difficult to achieve industrial application. The oily bubble flotation technology of low-rank coal greatly saves the cost of flotation regents and opens a new research direction for the industrial application of low-rank coal flotation. In this paper, the surface properties of long-flame coal particles, the sliding velocity of particles on the surface of a single oily bubble and the rising end speed of a single oily bubble in solution are studied by XPS analysis and high-speed camera technology, respectively. The sliding angular velocity of coal particles on the surface of oily bubbles is greater than the sliding angular velocity of particles on the surface of air bubbles in deionized water solution, indicating that the surface of oily bubbles is more hydrophobic than air bubbles; in deionized water or dodecyl hydrochloride (DAH) surfactant solution, the final velocity of oily bubble movement are obviously lower than the final velocity of the air bubble movement, and it is necessary to increase the stirring intensity during the flotation process to improve the mineralization efficiency between low-rank coal particles and oily bubbles.
- 1
Experimental Study on Seepage Law of Rough Fractures under Different Confining PressuresAbstract:
Understanding the fluid flow characteristics in fractured rock mass under stress coupling conditions is of great significance for guiding many rock engineering designs. To investigate the influence of surface roughness and confining pressure on the seepage of fractured rock mass, firstly, the topographic data of the prefabricated fracture surfaces were obtained by the use of three-dimensional topography scanner; water flow tests through non-mated fractured sandstone samples different roughness were investigated under confining stress from 1.0 MPa to 5.0 MPa. Experimental research show that the flow in unmatched sandstone fractures increases with the hydraulic gradient, and the Forchheimer equation can describe the nonlinear relationship between hydraulic gradient and flow well when the confining pressure is constant. When the confining pressure and hydraulic gradient are not changed, the flow rate in the fracture decreases with the increase of roughness. Further research imply that both the linear coefficient a and nonlinear coefficient b in the Forchheimer equation increased with the surface roughness and confining stress. The apparent hydraulic conductivity is not constant, its value decreases with the increase of Reynolds number, and the hydraulic aperture eh decreases with increasing confining pressure.
- 1
Experimental Study on Synergistic Reinforcement of Uranium Tailings and Prevention of Uranium Element Migration by Two Kinds of MicroorganismsAbstract:
It is very important to prevent the diffusion and migration of uranium element while reinforcing the dam body of uranium tailings dam. In this paper, the technology of microbial induced carbonate precipitation (MICP) was combined with the prevention and control of radioactive contamination. Bacillus pasteurii and Bacillus licheniformis were used simultaneously, aimed at studying the solidification of uranium element in uranium tailings reinforced by calcium carbonate produced by the mineralization of microorganisms. Through the analysis of the permeability coefficient of uranium tailings column, the change of uranyl ion concentration in leachate and the experimental data of soil mechanics after reinforcement, the synergistic effect of two kinds of microorganisms on the experimental results was obtained. The results show that: After 14 days of grouting reinforcement, the permeability coefficient of the synergistic test group of Bacillus pasteuri and Bacillus licheniformis was reduced to 12.5% of the initial value, at the same time, the test group of Bacillus pasteuri was 13.9% of the initial value. The uranium concentration of the leachate of uranium tailings was reduced to 0.056mg/L and 0.071mg/L respectively. In the triaxial shear tests under different confining pressures, the peak value of the stress-strain curve is more than two times higher than that of the original uranium tailings. In conclusion, Bacillus licheniformis can significantly reinforce the sand and prevent the migration of uranium in uranium tailings. This provides basis and support for the reinforcement of uranium tailings and preventing pollution in uranium tailings impoundment.
- 1
Research on Beneficiation Technology for Comprehensive Recovery of a Copper, Cobalt, Sulfur and Iron OreAbstract:
A copper-cobalt-sulfur-iron ore contains 0.56% copper, 0.074% cobalt, 9.20% sulfur, 25.90% iron, 88.93% copper produced in the form of primary sulfide, 90.54% cobalt occurring in pyrite in the form of isomorphism, 41.58% iron produced in magnetite. In order to develop and utilize the ore resources, based on the study of ore properties, the research of copper-sulfur-cobalt sequential priority flotation technology and copper-sulfur-cobalt mixed separation flotation technology were carried out. Finally, the copper-sulfur-cobalt mixing - separation flotation - magnetic separation of flotation tailings was determined. A copper concentrate with copper grade of 28.59% and copper recovery of 91.34%; Sulfur and cobalt concentrate with cobalt 0.34%, sulfur 45.47%, cobalt recovery 88.34%, sulfur recovery 86.91%; Iron concentrate with iron grade of 70.63%, sulfur content of 0.15% and iron recovery of 33.34% have been obtained. The comprehensive and efficient recovery of copper, cobalt, sulfur and iron has been realized.
- 1
Application of digital twin technology in mine Internet of things management and control systemAbstract:
The digital twin technology is applied to the mine Internet of things management and control system to build a three-dimensional digital twin model to map the real mine production environment, twin simulate the form and action of various elements of the mine production environment through data driving, and use the digital twin model to control the physical equipment to achieve the purposes of virtual real interaction, data synchronization and intelligent control. This paper studies the key technologies involved in the integration of digital twin and mine Internet of things management and control system, puts forward the theoretical system architecture after the integration of digital twin and mine Internet of things management and control system, and introduces the practical application of three-dimensional visualization module, equipment management module, safety early warning module and data visualization module of mine digital twin system in mines.
- 1
Simulation of the thermal environment of a mine based on VUMAAbstract:
As the mining depth continues to increase, the problems of high temperature and humidity in the underground environment have become increasingly prominent, seriously threatening the occupational health and production safety of workers. It is urgent to use numerical simulation to explore the distribution of downhole thermal environment and its influencing factors in order to take targeted cooling measures. Based on VUMA-3D, a mine underground thermal environment simulation was carried out. The changes in the underground thermal environment under different influencing factors such as the ground temperature gradient, surrounding rock heat transfer coefficient, equipment power, inlet wind speed and inlet wind temperature are studied separately. The results are obtained: every time the ground temperature gradient increases by 0.001 ℃/m, the temperature in the roadway increases by about 0.75 ℃; every time the inlet wind speed increases by 0.2 m/s, the roadway temperature decreases by 0.8 ℃. After the wind speed in the roadway reaches 2.4 m/s, the decrease in the roadway temperature changes to 0.34 ℃; the inlet air temperature decreases with a gradient of 0.62 ℃, and the return air temperature decreases with an average of 0.4 ℃. Increasing the wind speed and reducing the wind temperature make the combined cooling effect better, but the cooling effect is limited to the roadway with poor air flow. After the local ventilation method is adopted, the roadway temperature reduces from 28.3 ℃ to below 27.5 ℃, and the high temperature heat damage is improved.
- 1
Local Pressurization Ventilation System Design And Effect Analysis of the High-altitude MineAbstract:
To improve the low-pressure and low-oxygen environment in a high-altitude mining workplace, the local pressurization ventilation system of the high-altitude mine is designed. Based on three mathematical models of the local pressurization methods of resistance increase, energy increase, and leakage plugging, Ventsim is applied to construct and simulate the local pressurization ventilation system in a high-altitude mine. It is found that all the three local air pressurization methods can achieve the pressurization effect of the working faces; however, the air pressurization method combining resistance increase and energy increase works better than the single air pressurization method. When the mine axial flow fan’s power is 37 kw and the wind resistance value of the wind window is 4.00 N?s2/m8, the pressure of the working face rises by 730 Pa, which is equivalent to a 150 m drop in altitude. Therefore, the local pressurization ventilation scheme of high-altitude mine can effectively improve the on-site environment of low pressure and low oxygen in the working face. With this optimization scheme settling the ventilation network of a mine in Tibet, the air can flow into the workplace to the greatest extent so that on-demand ventilation can be realized, which proves to be a solution to the hypoxia in the high-altitude mining workplace.
- 1
Study on Ventilation And Spray Cooling Control Technology in Deep Mine With High TemperatureAbstract:
In order to solve the hazards of mine roadway high temperature environment, this paper studies the temperature field distribution of high temperature mine by means of theoretical analysis, numerical simulation and field application analysis. At the same time, the influence of different ventilation speed and ventilation temperature on the mine ambient temperature is simulated and analyzed, and the effect of spray cooling is analyzed. The research shows that increasing the ventilation wind speed can effectively reduce the mine ambient temperature. When the outlet speed of the air duct is 4m / s, the ventilation cooling effect is the best. The relationship between the ventilation speed v and the temperature T in the roadway is T= 300.79v-0.004 (R2 = 0.99); Reducing the ventilation temperature can further reduce the ambient temperature on the basis of increasing the ventilation wind speed. When the ventilation temperature is set to 288k, it can meet the requirements of ventilation and cooling at the on-site roadway heading face. According to the best ventilation parameters determined by simulation, on-site ventilation adjustment is carried out. Through monitoring, the maximum cooling value at the excavation face can reach 10.16k, and the highest cooling rate is 3.38%. Ventilation and spray cooling methods can ensure that the range of 5m within the roadway heading face has a good cooling effect, effectively alleviating the impact of high temperature environment on the workers.
- 1
Preparation and mechanical properties of phosphogypsum modified cemental backfilling materialsAbstract:
Based on the concept of "green mine", mineral solid waste such as phosphogypsum, cement and tailings were selected to prepare filling materials, and the fluidity, leakage rate and strength performance were tested. The mineral composition and microstructure characteristics were tested by X-ray diffraction and scanning electron microscopy. Finally, the hydration mechanism of filling materials was preliminatively explored. The results show that when the paste mass fraction is 72%~75% and the concentration of water reducer is 1.0%, the slump and bleeding indexes can meet the requirements of slurry pumping. The modification of phosphogypsum makes the early strength of cement-based filling material increase significantly. The material with 15% phosphogypsum content has the highest unconfined compressive strength. Calcium silicate hydrate and ettringite are the main hydration products in the phosphogypsum modified filling material. Under the modification of phosphogypsum, the content of calcium silicate hydrate and ettringite in the early hydration reaction is increased.
- 1
Model experiments on tailing pond dam failure under different rainfall conditions and potential economic loss assessment studyAbstract:
A rainfall breaching test apparatus for tailings ponds was used, using a tailings pond in Ganan as a prototype. Tailings pond breach model tests were conducted on the process of tailings pond breach, breach development, inundation extent and transit distance, deposition pattern of discharged tailings and assessment of potential economic losses in the impact area of the breach under different rainfall conditions (50 mm/h, 70 mm/h, 90 mm/h, 110 mm/h). The results show that as the intensity of rainfall increases, the damage to the dam becomes more severe at the same time stage, but the effect on the damage pattern of the dam is not significant. In the four sets of tests, the dam breaches generally developed in a "flared" pattern, with the width and depth of the final breach increasing with increasing rainfall intensity and showing different characteristics at different stages. The extent of inundation of the tailing sand flow after a dam breach varies with unit time in three stages, with the extent of inundation and transit distance varying with different rainfall conditions. The size of the tailings sand deposited downstream of the model decreases with increasing transit distance, with a large change in size at 120 cm from the model dam site. The risk of damage assessment resulted in a severity rating of "very severe" in the event of a dam failure under maximum rainfall conditions, with a risk of economic loss of 1.21% for the region, which would severely impact the socio-economy of the region. The research results can provide references for disaster prevention and control of tailings ponds under rainfall conditions.
- 1
IN-SITU STRESS DISTRIBUTION CHARACTERISTICS IN A’ERHADA LEAD ZINC MINE AND ITS APPLICATIONAbstract:
Under the condition of deep mining, the distribution rule of in-situ stress is an important foundation for rock mass stability analysis and engineering design. With the increase of mining depth in A’erhada mining area, the geological stress environment is complex and the surrounding rock deformation and damage is serious. In order to further study the stability of surrounding rock and its control measures during mining, the stress relief method was used to measure in-situ stress at 5 measuring points in 5 horizontal middle sections of the mining area. Based on the in-situ stress field model, the spatial distribution rule of the stress state and the relationship between the stress field and geological structure are analyzed. The results show that: the maximum principal stress and middle principal stress of in-situ stress field are close to the horizontal direction, and the minimum principal stress is close to the vertical direction; the ratio of measured maximum horizontal principal stress to the vertical stress is between 1.20 and 1.40, which indicates that the horizontal stress is dominant, and the average azimuth of maximum principal stress is 267 °. In the mining process of panel stope, the stress of surrounding rock transfers to the outside, and the stress at the top of stope and the intersection of stope joint roadway and chute is the most concentrated. Through the analysis of in-situ stress field and geological structure, the structural property of A’erhada NE trending fault is characterized by compression and torsion under the action of maximum principal stress direction, and the measured maximum principal stress direction is the same as that of regional tectonic stress field.
- 1
Study on Mesoscopic Parameter Calibration of Layered Rock Based on Particle FlowAbstract:
The calibration of mesoscopic parameters is of great significance to study the failure mechanism of the substratum in excavation unloading using PFC particle flow software.In order to calibrate particles and bond microscopic parameters, a large number of plane uniaxial compression and tensile numerical tests were carried out first.Taking the elastic modulus of particles, friction coefficient, stiffness ratio and elastic modulus of parallel bond, stiffness ratio, normal bond strength and cohesion as independent variables, the regression equations of rock uniaxial compressive strength, tensile strength, Poisson"s ratio and elastic modulus were fitted.Rock mesoscopic parameters determined by the regression equation, on the basis of using PFC2D software to simulate the intact rock specimen under uniaxial compression test, comparing the simulation results (macroscopic mechanical parameters, the stress-strain curve under similar conditions) and laboratory test results, the alignment is higher, thus verified the rock mechanics parameters and the effectiveness of bonded particles and parallel mesoscopic parameters relation.By carrying out 1:50 similar numerical calculation of calibrated mesoscale parameters, the law of roof fractures propagation in the mining process of single-layer ore and rock is revealed, which provides technical support for the instability mechanism and stability study of layered ore rock goaf in metal mine.
- 1
Identification of Surrounding Rock Block and Stability Analysis Method Based on Borehole TV DetectionAbstract:
Deep geological structure is more complicated than shallow one. Accurate engineering geological information is the key to safe and efficient construction of deep shaft. Based on the construction of section-930m~-946m of the new main shaft in Xincheng Gold Mine, in order to obtain detailed geological information of the deep part of the new main shaft, this paper collects rock mass joints on the surface of surrounding rock in the borehole for geological exploration by drilling TV, analyses and processes the collected rock mass joints with the in-hole TV image analysis software, and obtains the information of occurrence of the joint surface of borehole surrounding rock; and it is confirmed by Dips software. By defining dominant joint occurrence and using Unwedge to carry out stability analysis on potential wedge block of surrounding rock, the identification of structural plane of surrounding rock of shaft and its stability analysis method are established. This method is applied to the stability analysis of the new main shaft in Xincheng Gold Mine. The results show that the block safety factor is 19.75 minimum and the cut depth is 1.01m in the range of -930m ~-946m. The surrounding rock blocks of the wellbore are in a stable state without drop risk.
- 1
Research on Optimization of Ventilation System in the Second Mine of Jinchuan Based on 3D Digital ModelAbstract:
With the increase of mining depth, the underground ventilation system becomes more and more complex, and the control of mine ventilation becomes a difficult problem. To establish the ventilation simulation and optimization system of the second mine of Jinchuan, based on the measurement of ventilation resistance at a large number of measuring points by the base point method, the influence of mine ventilation difficulty, air density in different seasons, and natural wind pressure on the ventilation system was compared and analyzed. Using iVent three-dimensional software to establish a three-dimensional digital model of the ventilation system in the second mining area, three ventilation schemes are simulated and the best scheme is determined. The results show that the total air volume of the three optimized ventilation schemes is increased by 150 m3/s, 130 m3/s, and 20 m3/s respectively, which can improve the dust removal effect of the upper transport roadway and improve the ventilation efficiency. This model can provide a reference for the optimization and regulation of ventilation systems in similar mines.
- 1
Research and application of pilot empty hole technology for slope presplitting blasting in open pit mineAbstract:
Aiming at the slope presplitting blasting of open-pit mine, the calculation model of guided empty hole blasting is established, and the influence on presplitting blasting is analyzed from the diameter of guided empty hole, the decoupling coefficient of charging hole and the distance between charging hole and guided empty hole. Relying on the slope presplitting blasting of beskuduk open pit coal mine, according to the existing equipment model on site, it is determined that the aperture of presplitting hole and guide empty hole is 120mm, and the optimal decoupling coefficient is 1.5. Carry out presplitting blasting test under different hole spacing between charging blast hole and guide empty hole, and comprehensively evaluate the presplitting crack formation, half hole rate and flatness of retained rock mass. It is obtained that when the hole spacing is 2.2M, the presplitting crack is well formed, The damage degree of retained rock mass is the smallest, and the average forming rate of half hole of slope reaches 87.6%. The smoother the slope wall is, the better the foundation is, and there are no pumice and gravel. Good slope forming is achieved, which improves the stability of retained rock mass of slope and provides reference for similar projects.
- 1
Research of Mineral Processing Experiments on Arsenic-containing Gold Ore in Hunan ProvinceAbstract:
The average grade of valuable element gold was 3.40g/t in a gold mine in Hunan province，and all of the gold minerals existed in the form of natural gold.?Gold were mainly hosted in arsenopyrite and pyrite，and the contents of harmful elements arsenic and carbon were 0.36% and 1.42%, respectively.The dissociation analysis of gold showed that the recoverable gold mainly existed in the form of sulfide wrapped gold, monomer and bare gold, and the total distribution rate of the two was 94.69% under the condition of grinding fineness of -0.074mm accounting for 65%. According to the research results of the ore properties, the gold content of recycling were studied by flotation combined gravity dressing?technology under the conditions of grinding fineness of -0.074mm account for 64.1%. Firstly, gravity concentrate was obtained by shaking table gravity separation and panning, and then flotation concentrate was obtained by one roughing, two cleaning and three scavenging closed-circuit test process using the gravity separation and panning tailings as raw materials. Finally, the final product was obtained by combining gravity separation concentrate and flotation concentrate. The grade and recovery of gold in the final product were 113.91g /t and 93.14%, respectively. The difference between the actual recovery and theoretical recovery of gold was less than 2 percentage points.
- 1
Research and Prospect on Rock Impact Dynamics based on a Fine-scale PerspectiveAbstract:
The mechanical properties of different rocks vary considerably due to their genetic properties, and the evolution of fine-scale damage varies. Therefore, it is necessary to find the intrinsic link between macroscopic damage and the microstructure of rocks under impact loading to gain insight into the blasting properties of rock materials. This paper reviews the study of micro rock structure and its practical application in rock statics. The mainline is the correlation between the rocks" microstructure and its macroscopic impact dynamics. This paper introduces theoretical advances in the study of damage constitutive model based on introducing a micro-scale approach to rock dynamics. Meanwhile, the study of rock dynamics based on the acceptable view angle is introduced from the experimental and numerical simulation. Overall, this paper summarizes the research results related to rocks" microstructure and dynamics and provides an outlook on the future development of rock dynamics from three perspectives: theoretical, experimental and numerical simulations.
- 1
Multi-drainage Borehole Interference Theory Based on Velocity PotentialAbstract:
In order to obtain the characteristics of the gas flow field under the interference of multiple extraction boreholes, based on the velocity potential theory and its superposition principle, the method for determining the velocity field when multiple boreholes are jointly extracted is studied. Derive the equipotential line distribution equation and streamline distribution equation when the double boreholes with equal flow rate are mutually disturbed. Then the distribution characteristics of the streamlines and equipotential lines under the interference of the double boreholes, and the velocity change law of the main flow lines and the diversion lines of the two boreholes are obtained. The theoretical basis for the calculation of the position of the blank zone of the double boreholes is given, and the simulation verification is carried out by COMSOL Multiphysics. The results show that: the shape of the equipotential lines near the two boreholes that interfere with each other is two symmetrically distributed elliptical shapes, with their centers deviating to the outside of the boreholes. When away from the borehole, the shape of the equipotential line gradually changes from the Bernoulli double line to a circle. The coal gas around the borehole flows to the two boreholes respectively along a hyperbolic path. The flow velocity on the main flow line is the highest, and the velocity on the shunt line first increases and then decreases, and reaches the maximum value at 1/2 hole spacing from the balance point. The flow velocity inside the borehole is higher than the outside. The drainage blank area is generally formed near the balance point, and it is always biased towards the boreholes with small flow. The ratio of the distance from the balance point to the two boreholes is proportional to its flow.
- 1
Remote Sensing Monitoring of Chlorophyll-a Content in Coal Mining Subsidence Water AreaAbstract:
The monitoring and analysis of water quality in mining subsidence area is of great significance to environmental control and utilization in mining area. In paper, 15 water samples, which located in coal mining subsidence waters of Guqiao, Xieqiao, Gubei, Zhangji and Dingji mine, were collected using ASD spectrometer, then water samples also analyzed to obtain the chlorophyll-a content in laboratory. The correlation between chlorophyll-a content and original spectrum, first derivative spectrum, second derivative spectrum, derivative of logarithm spectrum and original spectrum were respectively analyzed. Based on spectral characteristics analysis, the wavelength range for chlorophyll-a inversion subsidence waters was gotten, and B4 band of Landsat8 OLI data was selected to invert the distribution of chlorophyll-a. The result shows that the inversion accuracy of chlorophyll-a in subsidence water area is good.
- 1
Research on Dynamic Floc Comprehensive Evaluation System Based on Deep LearningAbstract:
The treatment of coal wastewater is of great significance to the ecological and environmental protec-tion of the coal industry and the national "double carbon target". In order to solve the problems of poor solid-liquid separation effect, high drug consumption and lag in regulation and control caused by the difficulty of floc identification and evaluation in the process of coal wastewater treatment, a dynamic flocs comprehensive evaluation system based on depth learning is proposed. Firstly, a large number of different types of dynamic floc sample images are obtained, and the visual features of ef-fective flocs are extracted based on the floc texture parameters. The floc image is preprocessed, and the visual features of effective flocs are extracted based on texture parameters. Then, the principal component analysis method is used to obtain the comprehensive evaluation index of floc, the com-prehensive evaluation system of floc characteristics based on machine vision is constructed. Finally, the comprehensive characteristic probability distribution curve of flocs fitted by nuclear density analysis is dynamically clustered and the characteristic points obtained are used as the input of the classifier to build a classifier model to evaluate the settling effect of coal wastewater. The results show that the proposed method can obtain the image characteristics of dynamic flocs to realize the automatic identification and evaluation of the settling effect of coal wastewater. finally, the accuracy of the detection of the settling effect of coal wastewater in different states is more than 90%. It pro-vides a new method and new idea for the construction of intelligent coal preparation plant.
- 1
FEASIBILITY EXPERIMENTAL STUDY ON MINE BCAKFILLING WITH ELECTROLYTIC MANGANESE RESIDUEAbstract:
Greening is one of the main directions of the current development of China"s mining industry. However, a large amount of electrolytic manganese residue on the ground has seriously hindered the transformation and development of the enterprise. In order to efficiently dispose of electrolytic manganese residue, a feasibility experimental study on mine bcakfilling with electrolytic manganese residue was carried out. The results show that
- 1
Thoughts on the layout of mineral resources development under the goal ofAbstract:
The mining industry is a traditional high-energy-consuming industry. By analyzing the current status of carbon emissions in China’s mining industry, it points out the necessity of early layout in the mining field under the background of carbon peak and neutrality .The proposal of national " carbon peak and neutrality " target will further promote the green, low-carbon and circular development of mining industry; It established a carbon emission source model and accounting method for the mining industry, carry out carbon consumption flow analysis based on ore flow direction. Put forward three technical levels of basic technology system construction, key technology integration and coupling innovation, and disruptive technological innovation to comprehensively reduce carbon. The layout is carried out from four dimensions of industrial energy-technological process-process control-end treatment in mineral resources development. It provided new ideas and new plans for the " carbon peak and neutrality " layout of the mining industry, so as to ensure the sustainable development of mining industry and the realization of the dual carbon goal of mining enterprises on schedule.
- 1
Experimental Study on Comprehensive Recovery of a Complex Copper Polymetallic Ore with High Sulfur and Low Molybdenum ContentAbstract:
A mineral processing research on comprehensive recovery of a copper polymetallic ore with high sulfur and low molybdenum content was carried out. The polymetallic ore contains 0.57% copper, 0.019% molybdenum and 8.48% sulfur. A process flowsheet consisting of Cu-Mo bulk flotation followed by regrinding and cleaning of rougher concentrate and Cu-Mo separartion flotation, as well as extracting sulfur from tailings, was adopted. The results of beneficiation tests indicate that Cu concentrate with Cu grade of 18.06% and recovery of 78.88%, Mo concentrate with Mo grade of 45.98% and recovery of 60.22%, and S concentrate with S grade of 46.86% and recovery of 88.35%, were obtained. The comprehensive recovery of Cu, Mo and S from the polymetallic ore was realized by using this process.
- 1
1. Test raw materials and methods 2 Results and discussion 3 Establishment of settlement model 4 ConclusionAbstract:
Abstract: Based on the analysis of particle size composition and chemical composition of fine tailings, the influences of dosage of ferric chloride flocculant, slurry pH, dispersion time and slurry temperature on the flocculation and sedimentation effect of fine tailings were explored. The results show that when the flocculant dosage is 30mg/L, the slurry pH is 9, the dispersion time is 2min, the slurry temperature is 60°C, the clarification layer height is 159.7mm, the settling velocity is 15.97mm/min, and the turbidity is 16.25NTU, the settling effect of fine tailings is the best. At the same time, the settling velocity model of fine tailings is established, and the correlation coefficient R2 of the model is equal to 0.9568. The fitting result of the model is good and has high precision, which has certain guiding significance for the settlement process of fine tailings.
- 1
Study on Single Fracture Seepage Characteristics of Cambrian Oolitic Limestone Under High Temperature Triaxial StressAbstract:
Fracture seepage characteristics are very important for medium and deep geothermal development,in order to study the seepage characteristics of Cambrian oolitic limestone single fracture under high-temperature triaxial stress, the high temperature triaxial seepage test system independently developed is used to carry out seepage tests at different temperatures (RT-400℃), triaxial stress (20-35MPa) and high permeability pressure. The results show that: (1) At constant temperature, with the increase of axial stress（σa=20-35MPa，σc=20 MPa), the permeability of fractured rock samples increases gradually; (2) With the increase of lateral stress (20-35MPa), the permeability of fractured rock samples gradually decreases; (3) Under the condition of constant osmotic pressure, the permeability of fractured rock samples decreases with the increase of temperature during the temperature rise from RT to 400 ℃. At the initial stage of temperature rise, the permeability of rock samples with single fracture surface decreases rapidly, and the permeability is close to zero at 400 ℃. The research results provide a certain guiding significance for middle and deep geothermal development.
- 1
Study on Gas Control in Goaf by Large Diameter High Level Borehole instead of High Extraction LaneAbstract:
In order to solve the problems of tight mining and excavation, high mining cost and long construction period, large diameter high level boreholes were proposed to replace high extraction lane to extract gas from goafs, and the reasonable layout of boreholes was studied. Taking the 68310 working face of a mine in Shanxi as the engineering background, the analysis is carried out using FLAC3D simulation and on-site industrial test methods. The results show:The simulation shows that the height of the fracture zone is 34.2?m, and the height of the collapse zone is 12.5?m, which is basically the same as the theoretical calculation value. By comparing the stress concentration factor and pressure relief range of different borehole diameters, the optimal borehole diameter is 0.4m. The best hole spacing is 1?m. Field measured data shows that after the action of large diameter high level borehole, the gas concentration in the upper corner drops to about 0.37%, and the gas concentration in the return airway drops to about 0.28%. The scalar volume and the concentration of extraction are equivalent to those of high extraction lane, which is an effective solution. The problem of over-limit gas in the upper corner is solved, and the feasibility of replacing high extraction lane with large diameter high level boreholes is also confirmed.
- 1
Study on Mechanical Properties and Water Permeability of Iron Tailing Powder Alkali Slag ConcreteAbstract:
In order to reveal the correlation law between water glass modulus, fly ash amount , water-cement ratio, curing conditions and mechanical properties and water permeability of alkali slag concrete, cement, slag and fly ash were used as raw materials to prepare cementitious materials, and different modulus water glass was used as alkali exciter to prepare alkali slag concrete. The experimental results showed that while modulus of sodium silicate is increased from 1.0 to 1.5 the mechanical properties of alkali slag concrete increased first and then decreased and the permeability coefficient fluctuated less, showing a slow decrease and then a slight increase, and the water glass modulus of 1.2 was the inflection point of its performance change. The amount of fly ash amount was negatively correlated with the overall mechanical properties of alkali slag concrete. As the water-cement ratio increased, the mechanical properties of alkali slag concrete increased first. The mechanical properties of alkali slag concrete increase first and then decrease with the increasing of water-cement ratio, and the water permeability coefficient is linearly decreasing. The curing temperature and curing humidity are the key factors to determine the development of mechanical properties of alkali slag concrete. The compressive strength of alkali slag concrete at 3 d and 7 d under different curing conditions is ZC > steam curing, HC > moist curing after steam curing, MC > standard curing, SC > constant temperature and water curing, WC > indoor curing. NC, 28 d compressive strength ranked as HC>MC>SC>ZC>WC>NC.
- 1
Optimization of mining parameters of less gangue in undulating coal seams based on refined geological modelAbstract:
The study on the variation law of coal and gangue extraction in the working face has reference value for the intelligent and accurate mining of the mine and the rational planning of the mining scheme of the working face. Therefore, the fine geological modeling method of undulating coal seam is used to construct the fine geological model of undulating coal seam, and the low gangue recovery model of undulating coal seam is solved by using grid method / triangle method; Taking the mining height in the less gangue mining parameters of undulating coal seams as a variable, the relationship between the volume of coal and the volume of gangue in the model is studied. The results show that the triangle method is more suitable for solving the model; In the process of solving the mathematical model, with the continuous change of mining height, the function value of the mathematical model will reach the inflection point. Through analysis and control, the ratio of coal volume to mined gangue volume is greater than K / K, so as to optimize the parameter track of less gangue mining; According to the solution results of the example model, when the mining height is 5.2m and the ratio of coal volume to gangue volume is greater than 24.52, the parameter trajectory of less gangue mining reaches the optimum; Compared with the on-site mining height, the gangue production can be reduced by more than 35000 tons.
- 1
Study On Dam Break Process Of Tailings Dam Based On Model TestAbstract:
By using the similarity theory to establish the physical model of tailings dam break, Based on the design data of an actual tailing pond, The dam break of tailings dam in different height is recorded in detail, and to investigate the process of dam break in the flow, water level line and tailings downstream evolution. Experimental results show that: The overtopping and discharge has occurred in about 35 minutes for the tailings dam, At the same time, the flood peak has occurred at site of a dam and maximum flow is 4040m3/s, The propagation attenuation of flood peak has occurred along the way, the flood peak of downstream section gradually flat and has form of saw tooth; the breach width of dam of tailings dam(1285m elevation) is about 110m,about 50m depth; The width of the flow of downstream section is narrow; With the gradual downward movement of the water, the breach width firstly increase and then gradually slow down to balance; The characteristic section is closer to the tailings embankment, the greater the scour depth is occurred, The characteristic section is farther to the tailings embankment, the smaller the scour depth is occurred and erosion is getting narrower and narrower, and the more obvious the phenomenon of sediment deposition.
- 1
Pumping filling technology and application of coarse aggregate under long-distance and complex working conditionsAbstract:
This paper studies the problem of pumping and filling technology under long-distance and complex working conditions of coarse aggregate in phosphate mines. First, the coarse tailings crushing and screening test was carried out. The filling aggregate gradation is selected; the coarse aggregate slurry CSKY01 filling modifier is added to the slurry, so that the coarse particles in the slurry are inhaled and suspended, the fine powder particles are uniformly dispersed, the slurry is slippery and thicker, and the performance of the slurry is improved. The slurry has good fluidity in the pipeline, and the reasonable filling material and optimal gradation are determined. The following technologies were developed: (1) High-stability paste delivery technology with large diameter and low flow rate. (2) Large turning radius zero turbulence drag reduction conveying technology. (3) Separation and conveying technology of gelling slurry and non-gelling slurry. (4) Low-concentration slurry steady-state full-pipe down-flow pumping technology. It solves the technical problems of traditional filling system pumping paste slurry under long-distance and complex working conditions, such as: blocked pipe; large pipeline resistance; serious system damage, etc. The 8km pipeline and the filling of the 20km2 large mining area have been completed with low energy consumption and high reliability. After being popularized and applied in mines, good economic and social benefits have been achieved.
- 1
Experimental study on fluidity and strength characteristics of tailings slurry for filling of a vanadium-titanium magnetite oreAbstract:
Aiming at the problems of large fluctuation of slurry concentration, high filling cost, insufficient comprehensive utilization rate of tailings and poor filling quality of the full tailings filling material used in a vanadium titanium magnetite mine, the physical and chemical properties of the filling material were determined by carrying out the test of the full tailings cemented filling material. On this basis, the flow and strength characteristics of the full tailings under different concentrations and different ash-sand ratios were further studied and compared. The results show that : 1 ) The proportion of particles below ? 200 mesh in total tailings is 46 %, and the proportion of ? 20 μm particles is greater than 15 %, which can form ‘ structural flow ’, and the chemical composition is safe, which is suitable for underground filling ; 2 ) When the filling concentration is 64 – 74 %, and the cement-sand ratio is 1 : 4 – 1 : 12, the yield stress of slurry is less than 100pa, and the flow resistance of pipeline is less than 6.0 kPa / m. The filling slurry has good fluidity and good transportation performance. 3 ) In order to meet the requirements of mine safety mining 28d strength reached 1MPa and consider the filling cost, the best ratio of filling slurry is 74 % concentration, the ratio of ash to sand is 1 : 8. The research results can provide reliable data support for the improvement of mine filling quality.
- 1
Analysis of Domestic and Foreign Differences in Valuation Methods in Mining Project M&AAbstract:
With the rise of China''s investment activities in overseas mining projects, due to the lack of in-depth research on the difference between domestic and foreign value evaluation methods in the assessment process, valuation deviations affect merger and acquisition decisions and even cause incalculable economic losses. To address this issue, this paper analyses and studies the valuation purposes, pathways, and cash flow financial models of mining projects in China and abroad. It is found that Chinese and foreign mining enterprises face differences in mining policies and taxation systems in the process of mining project transactions. There also exist inconsistencies regarding the definition of appraisal objects, the identification of appraisal basis methods, and the selection of specific appraisal parameters. A comparison of qualitative and quantitative analyses was conducted to explore the main factors influencing the differences in the value of China and foreign mining projects. The principal findings include differences in the scope understanding of the evaluation subject, differences in the purpose of the evaluation, and differences in the selection of specific methods in each evaluation pathway. In addition, it also includes the domestic and overseas differences regarding the required contents of the appraisal, the composition parameters, and the calculation of parameters when using the cash flow method. Finally, the impact of the above differences in the valuation results is verified by taking a copper mining project in the south-central region of Africa as an example. It provides a reference for China and foreign M&As of mining projects and can improve the effectiveness of M&A project evaluation.
- 1
WANG Jingkun1,2,YU Yanmei1,2Abstract:
In order to study the dissolution law and weakening law of mechanical properties of glauberite salt rock under water dissolution at different temperatures,The real-time micro CT scanning and uniaxial compression test of glauberite salt rock dissolved in fresh water at different temperatures were carried out with a real-time loading and heating leaching test device during CT scanning.By comparing and analyzing the real-time dissolution and crystallization and mechanical characteristic parameters of glauberite at different temperatures, the dissolution and crystallization law of glauberite at different temperatures is summarized, and the weakening mechanism and law of mechanical properties of glauberite salt rock are revealed.The findings are as follows:(1)The porosity of glauberite increases from 0.96%-2.65% to 16.60%-18.41% after complete dissolution and crystallization.(2)The change of dissolved crystallization thickness of glauberite with time follows a power function,which can be expressed as:.(3)When the leaching temperature is 35℃,the dissolution rate increases greatly compared with 20℃,while when the leaching temperature is 35℃ to 80℃, the dissolution rate increases,and increased at 95℃.(4)There is a linear relationship between the cross-sectional area S of the undissolved crystalline area and the uniaxial compressive strength P. For the specimen with a diameter of 20 mm, it can be expressed as:. The research results have certain guiding significance for water-soluble mining of salt deposits, salt cavern gas storage construction and engineering stability study of rock mass corrosion problems in other glauberite -containing mirabilite projects.
- 1
Study on Strength properties of Cement-based Cemented Backfill Controlled by Different FibersAbstract:
In order to improve the stability of the filler and the filling quality of the extraction area, polypropylene fiber, polyacrylonitrile fiber and glass fiber were used as reinforcing agents, and the influence law of the different doping amounts of the three fibers on the mechanical properties of the tailing sand cemented filler was explored, and the damage pattern of the cemented filler under the action of doping fiber and no fiber was compared. The test results show that: the compressive strength of the cemented filler increases with the increase of fiber dosing, and then decreases, and the compressive strength of the filler reaches the optimal value when the fiber dosing is 0.6%. The gain effect of fiber on the filling body flexural strength is better than the compressive strength, when polypropylene fiber dosing 0.9%, polyacrylonitrile fiber dosing 1.2%, glass fiber dosing 1.2%, the flexural strength of the cemented filling body reached the optimal value, the maximum increase of fiber-doped cemented filling body 3 d, 7 d, 14 d and 28 d is 157.89%, 216.00%, 217.86%, 143.40%. Under uniaxial load damage, the specimens without fiber-filled body showed multiple long and wide penetrating cracks with more fragments falling off at the corners, while the specimens with fiber-filled body showed only fine and short micro-cracks, and the specimens maintained a high integrity. The hydration products of fiber-doped filler are mainly calcium alumina, C-S-H gel and Ca(OH)2, and the junction of fiber and filler matrix is wrapped by a large amount of hydration products, which can effectively inhibit the crack expansion, increase the bonding force and resistance to external deformation of the filler structure, and make the filler maintain high mechanical properties.
- 1
Study on temporal and spatial evolution of mining depth and surface rock movement in Beiminghe Iron MineAbstract:
The Large scale surface collapse occurred in Beiminghe Iron Mine due to the underground mining. With the continuous downward movement of mining depth, the scope of surface collapse gradually expanded, which seriously threatened the safety of surface structures and Beiming River in the south of the mine. To ensure safe and reasonable underground mining and effective control of surface rock movement, based on the ore rock distribution in the plan of each production level of the mine, a refined numerical model in line with the actual situation of the mine is established by using the 3D modeling software Rhino. Then, the refined numerical model is imported to the FLAC3D for finite difference calculations under the action of self-weight stress and mining stress. The temporal and spatial evolution of mining depth and surface rock movement is studied by simulating the successive mining of ore body, and the surface rock movement range corresponding to different mining depth is predicted. Comparing the current situation of surface rock movement in Beiminghe Iron Mine, the final range of surface rock movement in deep mining is determined. The results show that with the increase of mining depth, the surface rock movement can be divided into three stages: continuous stable, slow increase and significant increase. When mining to -144 m level, the possibility of surface collapse is greater. When the mining reaches the -230m level, the surface rock movement range reaches the north bank of Beiming River, which has a great impact on the river. At this stage, the certain surface rock movement control measures should be taken to ensure the safety of the river.
- 1
Study on the Performance of Modified Cementitious Filling Cementitious Materials with Styrene EmulsionAbstract:
In order to solve the problems of high water secretion rate, poor compatibility and low quality of filler caused by the use of fine-grained tailing sand in a gold mine, benzene propylene emulsion was used as a modifier and the effects of different amounts of benzene propylene emulsion on the performance of cementitious filler cementitious materials were compared and analyzed. It was found that with the increase of PPE emulsion, the flow, collapse, consistency and compressive strength at each age of the filling slurry showed a tendency to increase and then decrease, and the water secretion rate showed a tendency to decrease and then increase. Under this condition, the flow, collapse and consistency of the filling slurry increased by 20%, 17.14% and 5.1%, respectively, and the water secretion rate decreased by 28.04%, and the compressive strength of the filling body increased by 25%, 18.68%, 24.23% and 24.68% in 1d, 3d, 7d and 28d, respectively. The mechanical properties of the filling slurry meet the requirements of the mine. The microstructural morphology of the filler was observed by SEM scanning electron microscopy under the modification of different doping of benzene propylene emulsion, and it was found that the dominant hydration products of the filler were needle-rod calcium alumina and agglomerated flocculent hydration C-S-H gel. The microstructure morphology changed from a sparse honeycomb structure to a laminate with high stacking density, and the interlocking lap of calcium alumina and C-S-H gel linked the aggregate particles into a whole, so that the filler had a high mechanical properties.
- 1
A Review of Preparation of Geopolymer with TailingsAbstract:
The amount of various tailings in China is large at present, the large-scale utilization of tailings is difficult, and the impact of tailings on the environment is great. Geopolymer is a new type of cementitious material, and its production process not only can consume a large amount of industrial solid wastes, but also does not emit CO2 directly. It is a low-carbon building material and has become a research highlight. This paper outlines the research status of geopolymer preparation from tailings, expounds the effect of tailing types, activator kinds, curing condition, and so on, on the mechanical properties and the durability, summarizes the main research results, and puts forward the problems that need further research. The current research shows that the ideal geopolymer cannot be prepared by using tailings alone. It is necessary to add correction materials such as metakaolin, ground granulated blastfurnace slag or fly ash to prepare geopolymer based materials that meet the requirements.
- 1
Experimental Study of Propagation Law of Shock Wave Passing Through Reverse Outburst Prevention Air Door Hole Under Different Outburst CaliberAbstract:
In order to study the influence of the outburst caliber on the propagation law of shock waves through the reverse outburst prevention air door (taking bottom sill of the air door as an example), a coal and gas outburst simulation test equipment and the corresponding three-dimensional numerical simulation geometry model were established. Based on physical experiment and numerical simulation, the propagation law of shock wave on passing through reverse outburst prevention air door under different outburst pressure and outburst caliber conditions was studied. The results show that the shock wave passed through the roadway at a extreme fast speed after the outburst, mainly along the straight roadway. In the meanwhile, the change of the shock wave overpressure did not complete at once, it accompleted within 0.6s. And a small parts of shock wave continued passing through the the air door''s apertures due to the block of the reverse outburst prevention air door, and the rest parts of the shock wave were reflected when it collided with the air door. The smaller of the air door''s bottom canyon, the greater of the blocking effect of it. Therefore, a reasonable size of the air door''s bottom canyon can prevent the occurrence of secendary accidents. And the trend of the shock wave overpressure is similar under different outburst pressure and outburst caliber, it will become greater along with greater gas outburst pressure and bigger outburst caliber. When the outburst caliber is smaller, the shock wave speed will decay slower, the overpressure curve will be smoother, and the duration of overpressure changing will be longer.
- 1
Configuration of safety accidents in metal and non-metal mines based on 24Model and CSQCAAbstract:
In order to explore the cause factor configuration of safety accidents in metal and non-metal mines, 19 typical safety accidents in metal and non-metal mines with clear causes were selected by collecting many cases, and the occurrence frequency and average death toll of various accidents were analyzed.The 24Model analysis model is adopted to consider the influencing factors leading to accidents from six levels: unsafe physical state, unsafe behavior, individual factors, safety management system, safety culture and external factors of the organization, and the clear set qualitative comparative analysis method (CSQCA) is used for accident configuration analysis.The research shows that the analysis results of 24Model and CSQCA can effectively explore the cause configuration of metal and non-metal mine accidents;There are five typical paths between the cause factors and results, and the coverage of mine safety accidents triggered by different paths is also different.The study preliminarily analyzes the occurrence mechanism of safety accidents in metal and non-metal mines, which not only provides a new theoretical method for safety management of metal and non-metal mines, but also improves the economic benefits of metal and non-metal mines.
- 1
Stability analysis and support optimization of deep high stress shaft wallAbstract:
In order to solve the problem of deep support of blind shaft (1602m from the surface) in a mine in Yunnan, the surrounding rock stability of blind shaft is studied by means of field experiment, indoor experiment and numerical simulation. Macroscopic mechanical parameters of rock mass are determined through on-site investigation of rock mass discontinuity and rock mechanics experiments. FLAC3D numerical simulation of blind shaft is carried out by using theoretical calculation methods. And the construction risk level is divided. In addition, the blind shaft support mode and parameters are determined. The results show that 1031~992m is the construction base section and 992~942m is the construction dangerous section. With the increase of depth, the maximum principal stress increases, and displacement in X, Y, and Z directions becomes larger and larger. The maximum principal stress at the edge of shaft surrounding rock should be less than 11.15 MPa. In the excavation state, almost all surrounding rocks are in an unstable state and need to be supported. According to the support optimization results, C30 steel fiber concrete support is adopted for 1031~942m elevation. About the elevation of 1031~992m, support thickness is 400mm. The support thickness of 992~942m elevation is 450mm.
- 1
The Interfacial Nano-bubbles generated by the Wettability regulation and Its Promotion on the Hydrophilic ParticlesAbstract:
The introduction of nanobubbles in the flotation system can effectively improve the flotation of microfine minerals, especially hydrophobic minerals, but how to use nanobubbles to improve the flotation of hydrophilic minerals is a challenge. In this paper, graphite oxide is used to represent hydrophilic particles, the nanobubble morphology is characterized directly by atomic force microscopy (AFM), and the wettability of the graphite surface is modulated by dodecyl alcohol ethoxylate (AEO-15) The interfacial nanobubbles were successfully generated by the temperature difference method, and the differences in the morphology and number of interfacial nanobubbles generated on the surface of graphite after wettability modulation by oxidation and surfactant adsorption were compared and analyzed. The effect of wettability-regulated interfacial nanobubble generation on flotation verified by flotation tests. The results of the study indicate that: The generation of interfacial nanobubbles is only related to the degree of hydrophobicity on the particle surface and not to the height of the graphite morphology. Compared to hydrophilic graphite oxide, more dense and homogeneous interfacial nanobubbles can be produced on its surface after surfactant adsorption. In addition, the introduction of nanobubbles can significantly improve the flotation recovery of hydrophilic graphite oxide. This study provides a method for generating interfacial nanobubbles on the surface of hydrophilic particles, which has implications for the flotation enhancement of other hydrophilic particles such as low rank coals.
- 1
Estimation of stress arching effect and self-supporting stability analysis in inclined backfilled stopeAbstract:
The underground mining in metal mines usually uses backfill technology to realize the ground pressure management of the stope. The key problems are the stress distribution in backfill and its self-supporting stability. Based on the phenomenon of stress arching effect in backfill, the relationship between the stress distribution in inclined backfilled stope and the three-dimensional geometric size was analyzed by using limit equilibrium method and numerical simulation; An empirical formula for predicting the vertical stress of the floor of the backfilled stope is proposed considering the hydraulic radius of the backfilled stope; the self-supporting stability of the inclined stope backfill with free exposed surface in two-step mining was analyzed by using limit equilibrium method and numerical simulation considering the stress arching effect obtained in the backfilled stope, and the cohesion required is obtained when the backfill is used as a self-supporting artificial pillar, The research results can provide theoretical basis for the preliminary design of barricades in metal mine.
- 1
Study on Electrical and mechanical properties of Multi-walled Carbon Nanotubes-Iron Tailings cement-based materialsAbstract:
Carbon nanotubes and iron tailings were used to modify cement-based composites. The effects of single and compound mixing of carbon nanotubes and iron tailings and their content on the mechanical, electrical, thermal and electromagnetic wave absorption properties of cement-based materials were studied. The results show that the addition of 0.05% of multi-walled carbon nanotubes effectively enhances the mechanical properties of cement-based materials, while the addition of 0.5% of multi-walled carbon nanotubes leads to increased agglomeration and weakens the mechanical properties of cement-based materials; The addition of iron tailings weakens the mechanical properties of cement-based materials, and the weakening effect becomes more obvious as the amount increases; the simultaneous addition of multi-walled carbon nanotubes and iron tailings has a superimposed effect; The incorporation of multi-walled carbon nanotubes and iron tailings both reduce the resistivity of cement-based materials.,but the change in the amount of MWCNTs has a greater impact on the resistivity and heating effect by compared with iron tailings; The superposition effect of the two mixed at the same time is obvious; when the electromagnetic wave frequency is in the range of 3-4GHz, the material with the addition of 0.05% and 0.5% of multi-walled carbon nanotubes has better electromagnetic absorption performance; in the range of 4-5GHz, the addition of 10% and 30% materials have better performance; and in the range of 3-5 GHz, the materials mixed with multi-walled carbon nanotubes and iron tailings have better performance.
- 1
The Research and Practice of An Open Pit Mining Technology under the Background ofAbstract:
The hanging wall mine is located in the lower reaches of the high slope and high dumping ground, and is clamped by the north and south sliding bodies. With the advance of inner row, mining hanging wall ore seems to be an inevitable choice, but due to more uncertainty, mining and non-mining, as well as how to mining, enterprises have to face difficult decisions. Based on the risk analysis of the project and the safety evaluation of the surrounding environment, the technology of “limited wedge-shaped inclined groove”is put forward, which integrates safety technology, slope control technology and mining technology, it avoids the “pain point”of production reasonably and solves the difficult mining characteristics of hanging wall ore under the background of double-height and double-slip. Technology more reflect “early prevention”, such as advance “pre-pressure”and “reserve”, and timely application of monitoring technology, scientific prediction and early judgment, so that accidents no longer accident. Through careful organization and scientific management, not only “mining”, but also “more mining”, greatly improve the recovery rate, control production costs, comprehensively improve the quality and efficiency of mining.The mining effect of the new process is obvious, which has positive significance for protecting the depleted phosphorus resources and prolonging the life of the mine.
- 1
Research on technical modification design and application of full tailingsfilling in an iron ore siloAbstract:
The original design of the filling system of an iron mine adopts the natural settlement tailings cemented filling scheme. Due to the problems of low filling concentration, high bleeding rate of filling slurry, serious segregation, overflow water running and mixing, and large washing water volume, the filling system is technically reformed. Based on the basic physical properties and flocculation sedimentation test of the whole tailings. a set of flocculant automatic adding system and air-water linkage washing pipe device are added through analysis and research, and the modified full tailings cemented filling system is debugged. The results show that : 1 ) After the completion of the transformation, the fine particle content in the filling slurry increases, and the slurry concentration increases from 75 % to 78 % ; 2 ) The bleeding rate of filling slurry decreased significantly from 20 % to 5 %, and the whole slurry showed structural flow state without segregation and stratification. 3 ) The overflow water in the upper layer of the sand bin is clearly clarified, and the solid content in the water is less than 300 ppm, which can be directly used by the concentrator without secondary treatment ; 4 ) The water consumption of filling washing pipe is greatly reduced, and the primary washing pipe is reduced from 30 m3 to 5 m3. The full tailings cemented filling system after the transformation has realized full tailings filling and improved filling quality, which provides technical support for further mining.
- 1
Numerical Simulation and Underground In-situ Stress Monitoring of High-Stage Subsequent Filling MethodAbstract:
As the number of deep metal mines using the backfilling method gradually increases, the mining conditions change in a complex manner with the increase of depth, so the optimization of the mining structure parameters is an essential dynamic technical tool for the macro-control of the mining company. In order to analyze the feasibility of optimizing the structural parameters of the stope in a large underground mine, a test stope was established and numerical simulations were performed based on the mining process. By combining the results of in-situ underground stress monitoring in the test stope and the 3D scanning technology of the goaf to calculate and analyze the loss indicators, the feasibility of increasing the width of the block was determined. The result also provides important suggestions and research basis for future mine optimization design and ground pressure control technology.
- 1
Tensile and Compressive Strength Deterioration Model of Freeze-thawed Slope RockAbstract:
In order to study the slope rock mass of yulong copper mine, Tibet was under the influence of the freeze-thaw cycle of damage degradation, quartz sandstone and limestone of yulong copper mine, test to two main rock slope as the sample, based on nuclear magnetic resonance (NMR) technology for rock specimens under different freeze-thaw cycles porosity test, and adopts servo press and Brazilian splitting testing uniaxial compressive strength and tensile strength testing. The relationship between uniaxial compressive strength and tensile strength of two groups of samples and freezing-thawing cycles was studied, and the variation rules of porosity change and strength damage were analyzed. Based on porosity change, a strength deterioration model under different freezing-thawing cycles was established, and the model was fitted and verified by test data. The experimental results show that the uniaxial compressive strength and tensile strength of the two groups of rock samples decrease gradually with the increase of the number of freezing-thawing cycles, and the porosity change and strength loss rate increase gradually with the increase of freezing-thawing cycles. The relationship between porosity change and relative strength of the two groups of rock samples is exponential function and has a good correlation, indicating that the strength deterioration model established can well reflect the rock strength evolution law under different freezing-thawing cycles, providing a theoretical basis for the later mining technology of Yulong Copper Mine.
- 1
Study on Meso-structure and Fractal Dimension of Freezing-Thawing Rock in mining Slope of Cold RegionAbstract:
In the development of mineral resources in large cold areas of Xinjiang Uygur Autonomous Region, the problem of slope rock freezing-thawing disaster is prominent. In order to study the evolution characteristics of meso-structure of freeze-thaw rock on slope in cold region, 0~120 cycles of freeze-thaw tests were carried out, and the meso-structure parameters of rock during freeze-thaw process were obtained based on low field nuclear magnetic resonance(LF-NMR) technology. The analysis results show that with the increase of the cycles of freeze-thaw, the rock nuclear magnetic porosity presents three stages of variation. The T2 spectrum curve changes significantly during the first 20 cycles of freeze-thaw, and the variation is mainly in the second peak. The internal pores of cyclic freeze-thaw rocks have obvious fractal characteristics, and the fractal dimension of pores changes in a "V" shape with the increase of cyclic freeze-thaw times, and the fractal dimension is the smallest at 60 cycles of freeze-thaw. With the increase of fractal dimension, the complexity of pores increases and the connectivity increases. During the cyclic freeze-thaw process, the meso-pore dominated the evolution of rock structure.
- 1
Research on optimization of mining technology for open field and subsequent filling in staged rock drillingAbstract:
Aiming at the Laixin Iron Mine, the use of the unilateral propulsion staged rock drilling stage to mine the thick and large ore body with subsequent filling method has the problems of low production capacity and high loss rate. Combined with the current production status of the site and the mining conditions of the ore body, the optimization design of the currently applied mining method is carried out, and the industrial test is carried out on the site. The field application results show that the optimized stope structure parameters and arrangement can increase the stope production capacity by 112%, the ore recovery rate by 3% and the cost of transporting ore decreased by 18% (5.71 yuan / ton) compared with the previously applied single-side propulsion staged rock drilling stage empty field and subsequent filling method, and obtained good technical and economic indicators.
- 1
Study on Mechanical Properties and Flow Properties of Cement-based Filling Materials with Fiber ReinforcementAbstract:
In response to the problems of low quality, easy cracking and poor stability of the filler brought by the complex underground environment of deep mining, the local slag micronized powder, magnesium slag and desulfurization gypsum were used to develop low-cost cementing materials, and glass fiber was used as a modified material to regulate the mechanical properties of the filler. Firstly, the physical and chemical properties were studied based on the test materials; secondly, 25 groups of ratio combinations were designed by orthogonal test method to explore the influence of fiber dosing, fiber length and magnesia slag dosing on the flowability and mechanical properties of the filling slurry by comprehensive extreme difference analysis and analysis of variance. The test results show that: the increase of fiber content and fiber length per unit volume enhances the contact area between fiber and aggregate particles, blocks the normal flow of particles, increases the viscosity and yield stress of the slurry, and decreases the fluidity of the filling slurry. The development of fiber-regulated mechanical properties of the filler content not mean that the more the fiber content and the longer the fiber length, the better the improvement of the strength of the filler, with the increase of fiber content, fiber length and magnesium slag content the mechanical properties of the filler showed a trend of rising and then decreasing, when the fiber content of 0.6%, fiber length of 9 mm and magnesium slag content of 15%, the compressive strength of the filler took the optimal value. The extreme difference analysis and ANOVA showed that the influence of the test factors on the compressive strength of the filler at 1 d, 3 d and 7 d was ranked as fiber content > fiber length > magnesium slag content; fiber content was the main factor affecting the compressive strength of the filler at 28 d, followed by magnesium slag content, and fiber length had the least influence.
- 1
Effect of Tailing Particle Size on Rheological Properties and Mechanical Strength of Cement-steel slag-based Composite Filling SlurryAbstract:
To address the problems of poor flowability and low quality of the filling body of tailing sand filling slurry in a gold mine in Jiaodong Peninsula, we take the whole tailing sand as the research object, adhering to the concept of "treating waste with waste", "turning waste into treasure" and other solid waste resource utilization, and use local steel slag, desulfurization gypsum and other industrial solid waste with potential gelling activity to prepare new gelling materials. By conducting orthogonal tests, the effects of tailing sand grinding time, cement-sand ratio and slurry mass concentration on the rheological characteristics and mechanical strength of the filling slurry were investigated. The results showed that the slurry viscosity and yield stress increased with the increase of ash-sand ratio and slurry mass concentration. The finer the tail sand particles are, the more fine particles will accumulate in the effective flow of the slurry, which hinders the normal flow of the slurry, and the more sufficient the particle shear contact is, the larger the yield stress is. With the extension of tailing sand grinding time, the fine particles of tailing sand fill into the large pores of the cementing system, which improves the density of the filling body, and the compressive strength of the filling body shows an increasing trend, but when the tailing sand grinding time exceeds 45 min, the content of coarse particles of tailing sand, which plays the role of skeleton support, is relatively reduced, and the inter-particle structure is looser, so the later increase in the strength of the filling body is less obvious. The results of the extreme difference analysis of compressive strength found that the sensitivity of three factors on the compressive strength of the filling body was ranked as follows: slurry mass concentration > cement-sand ratio > tail sand grinding time.
- 1
Study on Massive Stone Consolidated Filling for the Goafs in an Iron MineAbstract:
It is a great potential safety hazard that the goafs below the surface in the surface iron mine. Blasting collapse cannot be used to deal with goaf at special locations such as under the final pit slope or under the surface structure. So it is best to use cemented filling reinforce this special goaf. The maximum grouting pressure required is obtained through measurement, calculation and experiment according to the geological condition of goaf and filling & grouting the goaf treatment process. After referring to the basic requirement on performance and preparation process of grouting materials, we measure,calculate and run trials on the the different grouting ratio of the filling body,and select the best grouting materials at last. The proportion of cement macadam powder is 5% : 95% , and the cement-sand ratio was 1:4. When the material is used to fill the goaf, it can totally meet the requirements and ensure the stability of the side slope.
- 1
Visual research and analysis of ecological environment assessment in mining areas in ChinaAbstract:
Mine ecological environment restoration and its effect evaluation is an important part of the construction of ecological civilization. In order to explore the research hotspots in the field of ecological environment assessment in mining areas and predict future trends, CNKI is used as the data source and the relevant literature of ecological environment assessment in mining areas from 1992 to 2021 as the object, and the bibliometric software CiteSpace is used for visual analysis of scientific knowledge graph. Spatio-temporal sequence analysis of journal literature citation networks, collaborating institutions and author networks. Combined with the analysis of citations and keywords, the research hotspots are sorted out and the development context is summarized. In the past three decades, the field can be divided into three stages: the initial embryonic period (1992-2000), the rapid development period (2001-2009) and the development stabilization period (2010-). The analysis of the cooperative knowledge graph shows that the high-yield authors are represented by Bai Zhongke, Xu Youning, Chen Yong, Yan Xuqian and Wang Yunjia. The main strength of research comes from major colleges and universities, and the top three institutions in terms of article volume are: China University of Geosciences, China University of Mining and Technology, and Central South University. Through combing and summarizing, the research hotspots in this field are summarized and mainly focus on the following four aspects: evaluation objects, evaluation methods, evaluation means and evaluation index systems. The future development of environmental assessment in mining areas depends on in-depth cooperation between research institutions, research teams and schools and enterprises, the improvement of the environmental assessment system, and the cross-integration of geographic information, computer, mathematics, ecology and other multidisciplinary research.
- 1
Study of Strength Properties and Damage Morphology of Polypropylene Fibers on Cementitious Filled CompositesAbstract:
In order to improve the stability of a gold mine tailing cemented filler and prevent sudden instability of the filler, a three-factor, four-level orthogonal design test was conducted with polypropylene fiber as reinforcing agent to investigate the changes of the filler slurry fluidity, mechanical properties of the filler and the damage pattern of the filler. The results showed that the fluidity of the filling slurry was negatively correlated with the amount and length of fiber, and the collapse and flow rate of the filling slurry decreased by 8.19% and 17.79%, respectively, with the increase of fiber dosing; the collapse and flow rate of the filling slurry decreased by 2.49% and 7.21%, respectively, during the increase of fiber length from 3 mm to 9 mm. The compressive strength of the filler with the increase of fiber dosing and length showed a tendency of increasing first and then decreasing, and the fiber dosing of 0.6% was the critical point, at which the compressive strength of the filler was 3.87 MPa, 9.32 MPa, 10.27 MPa and 11.88 MPa at the curing ages of 1 d, 3 d, 7 d and 28 d, respectively. The network structure can evenly disperse the external load and hinder the crack expansion, and the microcracks are many and small, so that the filling body can maintain a high integrity.
- 1
RESEARCH AND APPLICATION OF HIGH CAPACITY AND LOW COST FILLING TECHNOLOGYAbstract:
Sanguikou lead zinc mine is a typical difficult to mine ore body with complex occurrence and low grade, the original designed open stope method not only has serious dilution loss, but also the most important thing is that a large number of mined out areas can not be effectively treated, which brings great safety risk and mining difficulty to the mining of deep ore body. Therefore, after demonstration, sanguikou lead-zinc mine decided to adopt filling method for goaf treatment, and changed the mining method to filling method. Using high-capacity filling system to realize mining filling balance and control filling cost to a great extent is the key to filling mining in sanguikou lead-zinc mine. Through research, the continuous preparation process of short process transient tailings high-efficiency concentrated filling slurry of deep cone thickener is adopted to realize the tailings filling while sand feeding and concentration, and the filling flow can reach 180m 3/ h, it can be filled continuously for 24 hours with a filling capacity of more than 4000m 3/ d. The low-cost cementing agent with cement and fly ash as raw materials is developed, and the multi micro powder addition technology with multi bin configuration is adopted to realize the accurate addition of a variety of low-cost cementing agent components, which greatly reduces the filling cost, and the comprehensive filling cost is only 39 yuan RMB / m3. After the filling system of sanguikou lead-zinc mine is completed and put into use, it has successfully realized high-capacity and low-cost filling, which provides a favorable guarantee for the safe, green and efficient mining of sanguikou lead-zinc mine.
- 1
Research on the Key Technologies of Mining Area Special Railway Turnout ControlAbstract:
To improve the control reliability of mining area special railway turnouts control, reduce the accident rate caused by poor use of turnouts, improve the maintenance environment of special railway turnouts, and improve the management level of special railway turnout disease, this research has deeply and respectively researched four key technologies of mining area turnout relay circuit interface, power supplying, control combinations, and cable engineering. Finally the detailed designing scheme for the on-site turnout control system located in mining area railway has been proposed. It has been shown that the scheme meets the requirements of railway signal safety standards; could be independently applied in a mining area special railway station where there is no interlocking system, greatly reduces the installation cost of the special railway signal control system; plays an important role in ensuring the safety of the mining area special railway transportation.
- 1
Application of Mathematical Models in Tailings Concrete Performance OptimizationAbstract:
The tailings application to concrete was a form of environmental conservation and was important for the sustainable application of resources. The adoption of mathematical models in tailings concrete to promote experimental efficiency and to perform performance optimization studies was given wide attention. The current status of the application of single mathematical models such as Discrete Element Method, Finite Element Method, Intelligent Algorithm and coupled models of multiple algorithms in the mechanical activation of ball mills, in the forecast of compressive strength of tailings concrete and in the analysis of damage mechanism of tailings concrete were reviewed. The comprehensive analysis resulted in the development of new intelligent algorithms or combining multiple algorithms applied to tailings concrete, which could have broad application prospects. Therefore, development of coupling platforms and algorithms for multiple computational models should be vigorously pursued in this research area, research on the organic combination of experimental data and simulation results should be strengthened , and the development and application of the design of a general model software package for tailings concrete should be accelerated.
- 1
Optimization of Stope Drawing Step in Caving Method based on PFC3DAbstract:
The structural parameters of pillarless sublevel caving mining method are important factors affecting ore drawing loss and dilution. Based on the caving stope of an iron mine, a THREE-DIMENSIONAL numerical model of the caving stope was established based on THE PFC3D software. The sublevel height (21m) and the distance between approaches (20m) were kept unchanged, and the drawing step distance was optimized. The results show that the height of drawing body increases with the increase of drawing step, but it has little change when the drawing step reaches 5.0m. With the increase of ore drawing step, the drawing body of near ellipsoid shape develops from "short and thick" to "slender". The reasonable range of ore drawing step is 5.5m~7m after comprehensive consideration of recovery rate, dilution rate and poverty recovery difference index. Then the physical similarity model is established and different ore drawing steps are taken for experiment. Combined with the laboratory physical drawing conclusion and three-dimensional single drawing numerical simulation conclusion, the optimal drawing step range is 5m~6m under 21m×20m stope structure parameters, taking ore recovery index as the comparison object.
- 1
Experimental Research on Magnetic Separation and Recovery of Converter Steel SlagAbstract:
China's steel slag emissions are huge and lack of effective recycling. The total iron grade in a certain converter steel slag is 30.71%, and the useful minerals are mainly metallic iron and iron oxide phases, which are embedded in the steel slag in the form of lumps or strips, and have poor grindability. Based on the study of the nature of the original ore and the embedded state of the fine-grained useful minerals, the process flow of grinding classification-weak magnetic separation is adopted. The grinding product +0.5mm grain size can be classified in time, and an iron concentrate 1 with a grade of 92.80% and a recovery rate of 56.90% can be obtained. Then, the -0.5mm size sample was subjected to wet magnetic separation under the condition of a magnetic field intensity of 0.15T, and an iron concentrate 2 with a grade of 54.73% and a recovery rate of 11.31% was obtained. Compared with the traditional grinding-magnetic separation process, the difference in hardness is used to select qualified products in time, which greatly saves energy and reduces the cost of beneficiation. It has certain industrial promotion value and technical reference significance.
- 1
Source and Control of Abnormal Rock Movement Dislocation in South Ventilation Shaft of Xiaowanggou Iron MineAbstract:
Simultaneous caving mining method in upper, middle and lower three areas was applicated in Xiaowanggou iron mine. After a collapse pit was formed in the lower mining area, the surface cracks gradually expanded to the head of the south wind shaft at the end of 2018. As the surrounding rock of the shaft wall fell, an arc-shaped cavity with a width of about 0.2m was formed on the surface close to the shaft wall. So that the stability of south ventilation shaft was seriously affected. In order to ensure the normal operation of the ventilation shaft, the field investigation of rock mass structure from wellhead to collapse area and theoretical analysis were carried out. It is concluded that abnormal rock movement dislocation of south ventilation shaft is due to the cracking of the high angle structural plane in the rock mass and the rock mass near the South air shaft, as well as close to the maximum radial movement rate of the cut dispersion easier access to sidewall rock movement space. Meanwhile, a control method, filling the collapse area and limiting the dumping rock movement of surface cracks combined with the timely secondary support of the shaft wall failure area, is proposed. The rock movement monitoring data and field observation signs showed that, the mining rock movement rate at the wellhead was effectively reduced and the anti dislocation ability of the wellbore was enhanced. It proves that the method is a new safe, reliable, economical and practical method for dealing with abnormal dislocation of ventilation shaft in metal mines.
- 1
Experimental study on cemented filling with flotation ultra-fine tailings of phosphorus mineAbstract:
The flotation tailings of phosphate rock have the characteristics of fine grain size and high silt content, so it is difficult to cure with traditional cement cementitious materials and its strength is low. Combined with the practice of underground filling mining of a phosphate mine in Kunming, the feasibility of using high-performance cement to fill flotation tailings was experimentally studied and demonstrated. The results show that: the curing strength problem of ultra-fine flotation tailings filling can be well solved by using high-performance cementing material technology. Compared with the scheme of adding crushed stone, the cost of direct filling can be reduced by half. At the same time, the influence of cement-sand ratio, concentration and curing age on the strength of filling body was studied, and it was found that: the influence of cement-sand ratio and concentration on strength is linear, and the relationship between curing age and strength can be described by Logistic function.
- 1
Experimental Research on Beneficiation of Pingquan Xiaosigou Molybdenum MineAbstract:
In order to better recover valuable metals, improve the economic efficiency of the mine, and solve the problem that copper and some copper-molybdenum conjoined bodies were not effectively recovered in the previous industrial production without targeted collection of copper. This test optimizes the molybdenum priority flotation process, determines the copper-molybdenum mixed flotation-copper-molybdenum separation-integrated copper recovery process, and applies high-efficiency copper collector B-1 and high-efficiency argillaceous gangue inhibitor CD-2 . Under the conditions of 0.086% Mo grade and 0.100% Cu grade in the original ore, through the closed-circuit test of the whole process, the Mo grade in the molybdenum concentrate is 50.95%, the Cu grade is 0.24%, and the Mo recovery rate is 85.18%; the Cu grade in the copper concentrate is obtained. The good beneficiation index of 23.31% and Cu recovery rate of 70.16% provides data support for molybdenum ore beneficiation design and on-site transformation.
- 1
Effect of Slag Content on Mechanical Properties of Filling BodyAbstract:
In order to reduce the harm of coal-based solid wastes such as furnace bottom slag to the environment, furnace bottom slag can be added to the undergroundfilling materials mainly composed of coal gangue and fly ash. The influence of furnace bottom slag with different mass ratio on the initial and final setting time, compressive strength, elastic modulus, deformation characteristics and stress damage value of the filling body was studied..The results show that with the increase of bottom slag content, the initial setting and final setting time of filling materials are shortened, the compressive strength at 28 days decreases, and the elastic modulus and peak stress increase first and then decrease.The stress-strain evolution process of backfill at 28 days can be divided into four stages: compaction stage, elastic stage, plastic stage and softening stage. The final failure form of the filling body is splitting failure, and the damage value at the peak stress first increases and then decreases with the increase of the mass ratio of furnace bottom slag.Thecost of cement is 320 yuant. the filling materials such as furnace bottom slag are self-produced in the coal electric chemical base, and the cost is negligible.Proper addition of furnace bottom slag reduces the amount of cement. While disposing solid waste, the cost of filling materials is also reduced by 9.9% ~ 18.3%, which has significant environmental protection value and economic value.
- 1
RSSI Improved Personnel Localization Algorithm in the Underground Mine Based on ZigBee TechnologyAbstract:
In order to improve the position accuracy of underground metal mine, the study of position algorithms based on RSSI distance measurement was carried out by using physical simulation experiments and computer simulation experiments. Based on characteristics of the engineering layout and the operational environment of the underground mine, with the guidance of the theory and technology of Internet of Things, the experimental scheme was optimized, and the experimental process and devices were designed. The RSSI distance measurement experiment and the position experiment were carried out by using the ZigBee-based hardware platform in the underground metal mine. The position experiment of BP neural network was carried out in the laboratory. The combined weight is determined according to the mean square error of the data, and the positioning accuracy is adjusted. Experimental results show that the position accuracy was improved and the interference of abnormal data was reduced by using the combine position model of trilateration and BP neural network.
- 1
Research on Lithology Intelligent Sensing Method of Drilling Parameters Based on PCA-BP Neural NetworkAbstract:
In view of the complex geological conditions and poor underground production conditions of underground metal mines, it is difficult to obtain rock stratum information parameters and low lithology discrimination accuracy during underground excavation, this paper proposes a lithology intelligent sensing method based on principal component analysis (PCA) and BP neural network to improve the intelligent level of excavation. Firstly, through theoretical analysis, the lithology intelligent sensing model of parameters while drilling based on PCA-BP Neural Network is constructed. Then, the "three layers in one" rock samples of three different lithology are simulated through similar materials, six parameters while drilling such as parameters drilling speed, rotary speed, drilling pressure, rotary pressure, rotary torque and mud pump pressure while drillingare obtained by using a special rock drill is used to drill the test bench. Finally, the theoretical model is trained and tested. The results show that compared with the traditional BP neural network lithology intelligent sensing model, this method reduces the amount of model calculation, and the accuracy of lithology intelligent sensing is effectively improved.
- 1
Open Stoping and Subsequent Backfill of Gently-inclined Fractured Orebody Based on Clustered Hydraulic Prop SupportingAbstract:
In view of the difficulty in roof support and low mining efficiency of the gently inclined broken water-rich deposit in Shuiyindong Gold Mine, the roof support technology was optimized based on the rock mass quality evaluation, the open stoping and subsequent backfill based on clustered hydraulic prop supporting was further proposed. The results show that the quality evaluation of the Q system rock mass of floor limestone, ore body clay siltstone and roof silty clay rock are all poor grades; the quality of floor, ore body and roof rock mass in the RMR method are respectively fair, poor/fair, poor. The DW25-250/100 hydraulic prop can effectively support the broken roof. The reasonable bearing capacity of the prop is 145.9~151.15 kN/m2, the spacing is 2 m, and the row spacing is 2 m. The entire row of pillars is drawn by flexible steel wire ropes to prevent lodging. Form a cluster-type coordinated support. The cluster-type hydraulic prop protects the headspace. Subsequent filling mining method arranges one mining strip along the inclination every 10 m in the ore block, and adopts wall-type mining and centralized filling in the strip, and no raw material is left between the ore blocks and stopes Ore pillars; ore loss rate is 7.4%, dilution rate is 4.7%, ton ore cost is 124.05 yuan, safety and economic benefits are obvious.
- 1
ANALYSIS OF STABILITY OF OPEN-PIT HIGH SLOPES WITH GENTLY-INCLINED SOFT INTERLAYERS UNDER RAINFALL CONDITIONAbstract:
Rainfall is one of the important factors to induce slope instability, to explore the influence of rainfall on the stability of open-pit high slopes with gently-inclined soft interlayers, combining engineering practice, based on the saturated-unsaturated seepage theory to simulate the percolation process of mine slope under different rainfall conditions, and calculate the slope stability using strength reduction method under the action of the rain. The results show that the soft interlayer obstructs the rainfall seepage channel and leads to the distortion of pore pressure curve. The growth rate of pore pressure on the vertical section of slope decreases from top to bottom, and the increment of the infiltration depth and slope face pressure gradually decrease in the same time period. Plastic deformation occurs along the soft interlayer in the course of rainfall, and the overall displacement of the slope surface will be abrupt after 6 hours of rainfall. The increment of displacement in the middle of slope under the four raining conditions is the largest, and the displacement at the bottom of the slope in the rainstorm condition increases sharply compared with other raining conditions. The stability coefficient of the slope reaches the lowest after 24 hours of rainfall and is less than the requirement of the technical specification, and the slope is in a dangerous state. The results provide reference for the prediction, protection and evaluation of slope stability under similar geological conditions.
- 1
Study on Fracture Propagation Law of Deep Well High Stress SandstoneAbstract:
For deep high stress coal hard roof caving hard problems, the impact of disasters is put forward under the condition of high confining pressure fracturing scheme and experimental research, the large size of true triaxial fracture seepage simulation device for hydraulic fracturing physical simulation experiment, the different liquid injection rate, different viscosity fracturing fluid media"s influence on the regularity of crack fracture with the, the results showed that: ① The increase of liquid injection rate can obviously shorten the initiation time of sandstone under high stress condition. ② The change of liquid injection rate has no obvious effect on the initiation pressure of sandstone under high stress condition. ③ The increase of fracturing fluid viscosity has a certain influence on the fracture width. By reasonable control of injection rate and fracturing fluid viscosity, the initiation pressure and initiation time of sandstone can be predicted in a certain range of test conditions. ④ High in-situ stress condition is the main factor affecting fracture development. Because of the existence of high horizontal stress difference, the fracture basically does not deflect, and a vertical minimum principal stress main fracture is formed. The research results have certain reference value for high stress crack roof in deep Wells.
- 1
Optimal Simulation Research on Parameters of Side Hole Blasting in Huibaoling Iron MineAbstract:
Downward large-diameter deep-hole mining has high-efficiency blasting recovery efficiency and low recovery cost, so it has been widely used in Huibaoling Iron Mine.However, its application in the field also has the problems of difficulty in controlling the side slope and serious collapse of the side slope, which seriously affects the safe mining of the mine.In order to reduce the problem of side gang collapse caused by blasting,In this paper, LS-DYNA is used to model and optimize the radial charge non-coupling coefficient of the blast hole and the distance between side holes. Through comparative analysis of the stress, crack growth pattern and number of key monitoring points in the excavation area and the protection area, it is found that, The larger the uncoupled charge coefficient, the better the control effect of the side panel, but at the same time the rock breaking effect will be worse.In addition, the greater the distance between the side holes, the larger the spine between the holes, and the more uneven the side edges. Through numerical model optimization research, it is determined that the optimal non-coupling coefficient of Huibaoling side holes is 1.65 and the optimal side hole spacing is 2.0m. Through field tests, it is found that the optimized blasting parameters can reduce the phenomenon of over-excavation and under-excavation, and realize the leveling of the side profile and the control of surrounding rock collapse
- 1
Study on the Wind Speed Distribution Law of Coal Mine Roadway Section under Different FactorsAbstract:
Intelligent control of roadway ventilation is an important guarantee to achieve efficient production in mines. In order to realize intelligent ventilation, one of the key technologies is the fast and effective acquisition of roadway air velocity. In this paper, based on the basic principles of computational fluid dynamics (CFD), we simulated the section position, inlet wind speed, lane height-width ratio and roughness of the roadway under different conditions, and quantitatively analyzed to determine the distribution law of roadway wind speed under different conditions, and found that: the section position, inlet wind speed, lane height-width ratio and roughness have no effect on the contour profile of the wind speed distribution of the roadway; the roadway wind speed has no effect on the contour profile of the roadway when it is not fully The closer the section location is to the entrance of the roadway, the farther the location of the average wind speed is from the top of the roadway before it is fully developed; the entrance wind speed does not affect the location of the average wind speed in the roadway when the wind flow is fully developed; the roadway aspect ratio and the average wind speed can be expressed as a qualitative function; the larger the roughness is, the farther the location of the average wind speed is from the top of the roadway. The results of the study help the mean wind speed of the roadway to be fixed and provide a strong guarantee for real-time monitoring of the roadway air flow in underground roadways using wind sensors.
- 1
Analysis of roof stress in overlapped goaf of the Gently Inclined Multi-layer OrebodyAbstract:
In the process of mining gently inclined multi-layer mines, a large number of mined-out areas are often formed, which are distributed at random in space. At this time, the overlap rate and stability of the roof of overlapping goaf are the key factors affecting the stope stability. According to the beam model theory and superposition principle, the stress mechanics model of the roof of overlapping goaf is established, the stress distribution law of the roof of overlapping goaf under different overlap rate is analyzed, and the stability limit state of the roof of overlapping goaf is obtained. Take the vanadium ore section of the Shanghengshan mining area as an example, the relationship between the roof stress distribution and the cavity overlap rate is analyzed. The results show that when the overlap rate of the cavity decreases gradually, the maximum principal stress in the roof of the overlapping cavity decreases gradually and the maximum shear stress increases gradually. When the goaf overlap rate of V8 orebody and V11 orebody decreases to 40%~48%, the roof of overlapping goaf occurs shear failure and becomes unstable.
- 1
THE AESTHETIC EXPERIENCE AND THE CO-CREATION OF EMOTIONS IN THE INDUSTRIAL HERITAGE NATIONAL MINE PARK ——THE CASE OF JIAYANG NATIONAL MINE PARKAbstract:
As a mining heritage landscape, National Mine Park provides tourists with a unique aesthetic experience in the interweaving of natural aesthetics and technical aesthetics from mine management, landscape ecological restoration to industrial tourism sites. This article discusses the ritualized situation shaping of the aesthetic experience in the industrial heritage national mine park and its role in the co-creation of local emotions, taking Sichuan Jiayang National Mine Park as a case study, through the interactive ritual analysis of aesthetic experience. It found that the Jiayang Mining Area National Mine Park uses the Jiayang Train, the Coal Museum, the Bajiaogou Traditional Workers’ Village and the Huangcun Mine as the space carriers, and reshapes it from the ruins of decline through ritualization and situational shaping. For an aesthetic space with a unique local temperament, it has realized the re-localization from the resource-exhausted declining mining area to the industrial heritage tourist destination. In the process of spatial transformation, the local emotional endowment of corporate managers and planners transfers emotional energy to local residents and tourists. This process of ritualization provide them with a mixed aesthetic experience of natural beauty and technological beauty, and achieving local importance through aesthetic experience and Co-creation of local emotions.
- 1
Ecological Restoration Evaluation of Coal Resource-based Cities Based on PSR Matter Element ModelAbstract:
In order to scientifically evaluate the ecological restoration of coal resource-based cities, based on the PSR model, the evaluation index system of urban ecological restoration of coal resource-based cities was constructed from three aspects of pressure, state and response. The matter element model of ecological restoration evaluation was established by using the combination weighting of analytic hierarchy process and entropy weight method. The coal resource-based cities in Heilongjiang Province were taken as the research object for empirical research. And the evaluation grade was determined by combining quantitative and qualitative methods. The results show that, the weights of pressure, state and response index layers are 0.2293, 0.2623 and 0.5058 respectively. Among them, the restoration index of mine wasteland (0.1292) and the comprehensive utilization index of solid waste (0.1154) are the main influencing factors. The ecological restoration level of Shuangyashan, Qitaihe and Jixi is grade II, and that of Hegang is grade Ⅰ. It is concluded that the matter element model based on PSR combination weighting is suitable for the evaluation of urban ecological restoration of coal resource-based cities. Hence, the research results of the said paper can provide a reference for the ecological restoration and sustainable development of coal resource-based cities of our motherland.
- 1
Study on the optimum design of ultra-fine tailings filling process in agold mine in GuizhouAbstract:
The rock stability of a gold mine in Guizhou is poor, and most of the old roadways have been scrapped or collapsed, which seriously restricts the mining efficiency and forms a large potential safety hazard. Therefore, it is proposed to carry out filling process research, through the construction of filling system, filling mining method is used for mining production. Firstly, the basic experimental study of mine filling tailings was carried out, and the physical properties and particle size distribution of filling tailings such as density, bulk density, void ratio were analyzed. Secondly, according to the selection principle of filling process design, the continuous preparation process scheme of tail mortar dense filling and the preparation process scheme of pressure filtration tail sand filling discontinuous paste are formulated. Finally, the two schemes are compared and analyzed from the aspects of process, investment and operation cost. The results show that : 1 ) Total tailings-200 mesh content is 95 %, belongs to superfine tailings, density is 1.33, porosity is 53.33 % ; 2 ) Filling 50 ~ 60 m3 / h, filling 7 hours a day, can meet the filling requirements, filling slurry concentration is about 60 % ; 3 ) Taking into account the investment of filling system, filling cost, technical reliability and other aspects, the continuous preparation process scheme of tail mortar dense filling has obvious advantages, and the continuous preparation process scheme of tail mortar dense filling is the best scheme of superfine tailings filling in the gold mine.
- 1
Experimental Study and Engineering Application of Full Tailings Cemented Filling in Huangshaping Polymetallic MineAbstract:
The original design of Huangshaping polymetallic mine adopted the upward horizontal layered waste rock filling mining method. Because of the large amount of development work, low stope roofing rate, difficulty in pillar recovery, and high filling cost, in order to make the mining safer and more efficient and reduce the filling cost, it is now replaced by full tailings cemented filling. Based on the basic physical properties, flowability and strength tests of tailings, the cemented filling technology of total tailings in Huangshaping polymetallic mine was proposed through analysis and research, and the research and construction of filling system were carried out. The results of field debugging and industrial test show that : 1 ) using full tailings as filling aggregate and new filling G material as cementing agent can meet the strength requirements of the filling process and mining method of the mine, and the tailings of the concentrator can be fully filled to the underground to achieve no tailings discharge ; 2 ) The filling slurry concentration is 67 %, the maximum filling flow is 80 m3 / h, and the cement-sand ratio is 1 : 6 ~ 1 : 10. The filling slurry can enter the filling area smoothly, and the slurry reaches the structural flow state, and all the indexes meet the requirements. The construction and application of full tailings cemented filling system provide technical support for high-quality and low-cost filling mining in Huangshaping polymetallic mine.
- 1
Optimization of Static Flocculation Settlement Parameters of Total Tailings based on Grey Relational AnalysisAbstract:
Through efficient flocculation and sedimentation, Low-concentrationmass fraction total tailings slurry is thickened to high-concentrationmass fraction underflow slurry, which is the foundation and key of cemented paste backfill. The static flocculation and sedimentation parameters of total tailings slurry were optimized by single factor experimental design and grey correlation analysis (GRA). The flocculant type (molecular weight), flocculant dosage, and feed dilution concentrationmass fraction were selected as the influencing factors. The relative flocculation rate, 24h underflow concentrationmass fraction, and solid flux in the process of flocculation and sedimentation were selected as the characterization parameters. The single factor test results shown that within the experimental design level, the relative flocculation rate first increased linearly with the increase of molecular weight, then tended to be stable; increased linearly with the increase of dosage; and decreased linearly with the increase of dilution concentrationmass fraction. The underflow concentrationmass fraction decreased linearly with the increase of flocculant molecular weight and dosage, and increased linearly with the increase of dilution concentrationmass fraction. The solid flux changed parabola with the three characterization parameters. The grey correlation analysis of the test results illustrated that the feed dilution concentrationmass fraction was the optimal influencing factor of flocculation sedimentation test, and the underflow concentrationmass fraction and solid flux were the quasi optimal characteristics of flocculation sedimentation. Moreover, the test parameters are optimized: flocculant type is 18 million APAM, flocculant dosage is 15%, feed dilution concentrationmass fraction is 18%.
- 1
Optimization of Underground Mining Methods and Selection of Supporting Production Equipment in High Altitude Large Copper Polymetallic MineAbstract:
The second and third bid sections of the second phase of underground mining of Jiama Copper Polymetallic Mine are the main mining areas.The ore body in this area is a near horizontal and very thick large ore body.The broken oxidation zone is widely distributed in this area,and mainly presents typical characteristics such as rich ore grade, high oxidation rate, joint fissure development and simple hydrogeology. It has adverse engineering effects on roadway excavation, stope rock drilling and explosive loading,mainly manifested in roof collapse, side slope collapse and so on.The existing sublevel upward medium deep hole subsequent filling mining method is difficult to improve the current situation of underground production, and there are still great potential safety hazards. In order to reduce the safety risk in the production process and ensure the safe, economic and efficient recovery of the ore body, the open stope and subsequent filling mining method of combined mining of downward large-diameter medium deep hole and upward fan-shaped hole is proposed to recover the ore body in the broken oxidation zone. This mining method is conducive to protecting the stope roof and preventing roof collapse. The arrangement of downward parallel holes helps to better control the stope boundary, reduce the side slope collapse caused by ore rock crushing, improve the stope production and operation environment in the broken oxidation zone, and has excellent popularization and application value
- 1
Application of Non-Metallic Anchor Mesh Shotcrete Support In Metal MinesAbstract:
This paper analyzes the problems existing in the roadway supported by metal anchor mesh shotcrete in the West Second Mining Area of LongShou Mine, Jinchuan, and puts forward the scheme of using non-metal anchor mesh shotcrete support instead of metal anchor mesh shotcrete support. In order to verify the feasibility of non-metal anchor mesh shotcrete support and explore the mechanical characteristics of the combined support of non-metallic mesh and shotcrete, the RDP（round determinate panel） test of non-metal anchor mesh shotcrete for different tensile strength was carried out, and the experimental results were analyzed from three aspects: specimen failure type, peak load and energy absorption. The results show that the order of energy absorption values of the three groups of specimens is B > A > C, the average RDP40mm of group B specimens is 283J, and the non-metallic mesh with tensile strength of 40kN/m can meet the requirements of the minimum toughness value of energy absorption 280J in roadway support. On this basis, combined with the field roadway support and deformation monitoring test, the feasibility of the support scheme is verified. The support cost and efficiency of the original support method and the improved support method are statistically analyzed. Compared with the metal anchor mesh shotcrete support, the installation efficiency of non-metal anchor mesh shotcrete support is increased by 25%, the bolt installation efficiency is increased by 12%, and the support cost is reduced by 43.8%. It is of great significance to reduce the support cost and improve the support efficiency.
- 1
INVESTIGATION ON EARLY WARNING TECHNOLOGY OF ROCK MASS FRACTURE INSTABILITY BASED ON MICROSEISMIC PARAMETERSAbstract:
Early warning before rock mass damage timely is important to ensure personnel safety with the increasing mining depth and ground pressure activities particularly. This paper talked a metal mine as an example using microseismic monitoring technology to analyzed the evolution characteristics of microseismic b-value parameters and putted forward EV-value representing the internal damage degree of rock mass, and analyzed its evolution characteristics. The analysis showed that microseismic parameters reflect the stability of rock mass better. It is analyzed that the large decline of microseismic b-value can be used as the precursory information of rock mass failure, and with the decrease of the number of microseismic events at the same time. The stage with the largest decline of EV-value can be used as the early warning period for a large-scale roof falling accident. The research results can provide reference for microseismic monitoring and early warning technology of rock mass damage in similar mines, so as to improve the timeliness and accuracy of disaster early warning and ensure safe production.
- 1
Slope Stability of Open-Pit Mines Evaluation Method Based on Game Theory Cloud Matter Element ModelAbstract:
In view of the fuzziness and randomness of slope engineering stability evaluation of open-pit mine, and to solve the problem that the weight calculation imbalance of single subjective and objective weighting method in the research process affects the reliability of evaluation results, a comprehensive evaluation method of slope stability of open-pit mine based on the combination of game theory and cloud matter-element is introduced. From the three aspects of rock mass mechanical properties, environmental conditions and engineering conditions, 12 factors are selected to construct the comprehensive evaluation index system of open-pit mine slope stability, and the game theory cloud matter-element coupling evaluation model of slope stability evaluation is established; The established comprehensive evaluation model is applied to the slope stability evaluation of three open-pit mines. G1 method and improved critical method are used to calculate the subjective and objective weights of the indexes respectively, and the comprehensive weights of the indexes are determined based on the idea of game theory; Then, the cloud matter-element model is used to calculate the single index correlation degree and comprehensive correlation degree. Based on the maximum membership criterion, the slope stability grade is comprehensively analyzed and judged, and the evaluation results are compared with the evaluation results of unascertained measure and attribute measure model to verify the accuracy of the model. The research shows that the slope stability grades of the three open-pit mines are grade III, grade II and grade III respectively, which are consistent with the actual situation, and the evaluation results of the three evaluation models are completely consistent, which verifies the applicability of the game theory cloud matter-element model in the slope stability evaluation of open-pit mines, and provides a new idea for the slope stability evaluation of open-pit mines.
- 1
Study on low cost mining technology and technology of ore body in West Second Mining area of Longshou MineAbstract:
According to the occurrence conditions and mining status of the ore body in the West Second Mining Area of Longshou Mine and the impact of the depressed international market on the product price, mining the lean ore in the West Second Mining Area by filling method is facing a serious problem of economic benefits. Therefore, a low-cost sublevel caving mining method without sill pillar is studied. According to the mining processes such as end wall forward inclination, uniform ore drawing, double leakage shovel, mining segmentation and route spacing, the technical parameters of sublevel caving mining without bottom pillar are optimized: the ore block mining is arranged into East and west mining areas along the ore body trend, and the mining is returned to the East and west respectively with the 8 exploration line as the boundary, and the raise boring machine is used to cut the 100m middle section at one time, Each section shall chisel upward parallel holes in the cutting roadway, take the cutting shaft as the free surface, and conduct mining and ore extraction after the section before the first row of holes of mining blasting is blasted to form a cutting groove. The caving mining process has been applied in the first mining isolation layer and diamond double roadway mining, and its ore loss and dilution rate have been effectively controlled, so as to obtain remarkable economic benefits. At present, it is being popularized and applied in Longshou Mine.
- 1
Flotation test research of an arsenic-bearing zinc ore in Inner MongoliaAbstract:
An arsenic-bearing zinc ore in Inner Mongolia has a zinc grade of 1.35%, and the harmful element arsenic content is relatively high, accounting for 1.06%. Among them, zinc mainly exists in the form of sulfide. In order to efficiently recover the arsenic-bearing zinc ore, technological mineralogy research and detailed beneficiation tests were carried out. The results show that: (1)When the grinding fineness is 49% at -0.074mm, the zinc blende monomer is dissociated, and the zinc recovery rate reaches 91.46%; (2)In order to determine the types or dosages of flotation inhibitors and collectors, experiments were conducted to determine that the arsenic mineral inhibitor was lime + sodium humate, the collector was Z-200, and the gangue inhibitor was water glass. 400g/t is appropriate; (3)The laboratory closed-circuit test obtained the zinc grade of zinc concentrate 49.02%, the recovery rate of zinc was 97.78%, and the content of arsenic was 0.71%. The grade of Zn in the tailings was reduced to 0.04%, and the efficient recovery of the valuable element zinc in the ore was realized.
- 1
Study of Sodium Sulfide to Regulate the Coagulation and Hardening Properties of Paste-filled SlurryAbstract:
In order to solve the problems of poor quality of filler, long mining and filling cycle, and low ore production efficiency caused by slow solidification and hardening of paste-filled slurry in a mine, sodium sulfide was used as a modifier to regulate the solidification and hardening performance of paste-filled slurry. The results of the study showed that sodium sulfide can play a significant role in promoting coagulation by passivating the zinc ions in the tailing sand-cement-slag-based composite cementitious system and accelerating the hydration reaction mobility process of alkali slag, and with the increase of sodium sulfide addition, the setting time of the paste-filled slurry showed a linear decreasing trend, the collapse and flow were negatively correlated, the consistency was positively correlated, and the compressive strength of the filled body at 7 d, 14 d and 28 d showed a rising and then decreasing trend. The compressive strength of the filling body at 7 d, 14 d and 28 d showed a trend of increasing and then decreasing, and the addition of 1.5% sodium sulfide was the inflection point of the change of compressive strength of the filling body. When the ratio of ash to sand is 1:8 and the addition of sodium sulfide is 1.5%, the collapse degree of paste filling slurry is 28.0 cm, the consistency is 11.4 cm, the flow degree is 73 cm, and the compressive strength of filling body at 7 d, 14 d and 28 d is 2.08, 3.11 and 3.99 MPa, which meets the requirements of mine filling and mining.
- 1
Parameter Optimization of Stoping Drifts by Filling Method Based on Combined Weighting under Massive BackfillAbstract:
Aiming at the problem of the rationality of the stoping drifts when the downward pach cemented filling method is adopted under massive backfill in the deep part of Jinchuan No. 2 mining area. Taking the 850m deep horizontal middle stope as the research object, nine groups of test plans with different stoping drifts width and height are determined according to the Mathews stability diagram method. Through numerical simulation, four indicators of stope maximum principal stress, maximum tensile stress, average yield rate and roof subsidence of different schemes are obtained. The response surface method was used to obtain the influence degree and change law of different path parameters on the four indicators. A comprehensive evaluation index system for optimizing the parameters of the stoping drifts was constructed. Using analytic hierarchy process and entropy method to carry out combined weighting, and through fuzzy comprehensive evaluation, it is concluded that the width of the stoping drifts is 5~6m and the layer height is 4~4.5m in the 850m horizontal middle section of the Jinchuan No. 2 mining area, which can achieve better comprehensive benefits. And when the width of the stoping drifts is 6m and the layer height is 4.5m, the comprehensive benefit is the largest.
- 1
Morphology analysis of draw-out body in caving method under ultra-high sublevelAbstract:
In order to deeply study the evolution law of the draw-out body form of metal mine caving mining method under the condition of far-field study, a single path natural caving drawing model was established to carry out the study of the drawing body form of far-field condition caving by combining physical experiment, theoretical analysis and numerical simulation. Based on particle discrete element software and particle cluster block, the numerical model of ore drawing is constructed and compared with the results of laboratory physical test and simulation. The results show that: 1) The shape of the draw-out body is not ellipsoid in the strict sense, and the draw-out body gradually takes on a slender "pencil shape" in the middle. With the development of ore drawing, the lateral tangential force of ore-rock bulk will limit the development of the width of the draw-out body due to the increase of the width ratio of the draw-out body. Compared with the development of the width of the draw-out body, the development of the height of the draw-out body is less affected. 2) Through fitting and comparative analysis of the morphological development results of the draw-out body obtained from physical tests and numerical simulation, the reliability of the numerical model of particle cluster ore drawing in the study of ore-rock flow characteristics of caving method is proved, and this kind of model can be used in the subsequent more complex ore drawing research
- 1
Research on Influencing Factors of Slump Parameters of Gobi Filling SlurryAbstract:
A newly-built filling station of a gold mine uses Gobi material for filling. In order to ensure the stability of filler slurry transportation, the influence of different particle sizes, different concentrations and different lime-sand ratios of Gobi material filler slurry on slump parameters was studied. The results show that the slump of the Gobi filler slurry varies with the change of particle size, concentration and lime-sand ratio. Concentration is the main factor affecting the slump value. The higher the concentration, the lower the slump value; the lime-sand ratio has a certain influence on the slump, but the influence of the lime-sand ratio on the slump is limited by the size of the Gobi material. The coarser the size of the Gobi material, the greater the impact of the lime-sand ratio. Therefore, when the Gobi material is filled, various factors should be considered comprehensively, and the suitable particle size of the Gobi material should be selected. At the same time, the fluctuation of the concentration should be reduced during the on-site production process to ensure the stability of the filling slurry transportation.
- 1
Research on ecological security safety warming technology and its applications in coal rich areasAbstract:
This study is based on the PSR model and LCCC to construct a warning indicator system for ecological safety in coal resource areas. It selects 26 indictors covering the four dimensions of economic, society, environment and ecology, use the range method to standardize the calculation of the above indicators, and the entropy method is used to weight the indicators, so as to obtain the ecological safety index of the study area. Taking Ordos as an example, the research results showed that the ecological security warning value of Ordos showed a fluctuating upward trend. From 2012 to 2018, the ecological security level of Ordos improved, and the comprehensive warning value from 0.4477 to 0.5558, with a growth rate of 24.15%. Among them, from 2012 to 2014, the comprehensive warning value decreased from 0.4477 to 0.2747, a decreased of 38.64%; from 2014 to 2016, the comprehensive warning value increased from 0.2747 to 0.5669, an increase of 106.37%. According to ecological safety classification standards, the ecological safety status has undergone a transition from “critical safety-less safety-critical safety”, and the alert level has changed from “medium alarm-heavy alarm-medium alarm”, indicating that the ecological environment of the region is still relatively poor.
- 1
Study of Reasonable Spacing of Parallel Tunnels with Soft Surrounding Rock and Tunnel Geological PredictionAbstract:
In view of the spacing size of the middle rock pillar and the bad geological boy play the important role in the construction process of parallel tunnels, in order to improve the safety in the tunnels construction process, the reasonable spacing size of parallel tunnels and advance geological prediction accuracy in construction process under the condition of soft surrounding rock are studied. With the guidance of theories of rock mechanics, numerical simulation models with different spacing size of parallel horseshoe-shaped tunnels were established and the stress state distribution of the middle rock pillar are obtained．Experimental results showed that the spacing size has a significant effect on the stress state of middle rock pillar and shall be more than 1.5 times the tunnel diameter under the condition of level V surrounding rock. The ground penetrating radar images can effectively distinguish the bad geological body in the surrounding rock in front of tunnel face and perform the non-contact detection of tunnel lining.
- 1
Simulation and Application of Pressure Relived and Permeability Enhanced Law of Perforated Hydraulic Slotting Borehole on CoalAbstract:
In order to study the influence of drilling Angle of perforated borehole and slot diameter on pressure relived and permeability enhanced of hydraulic slotting. In the background of typical low permeability coal seam, the FLAC 3D numerical simulation method was used to calculate and comparison analysis of the hydraulic slotting model of 1.1, 1.2, 1.3, 1.4, 1.5m slot diameter and 50 °, 60 °, 70 °, 80 °, 90 ° drilling angle. The results show that The plastic failure area around the seam drilling is linearly correlated with the diameter of the slot. The influence range of the tow is a logarithmic function relationship with the diameter of the slot. The circumferential damage area around the seam drilling is positively correlated with the drilling inclination, and the mutation occurs between 60 ° and 70 °. The scope of the seam affects the power function relationship with the drilling inclination. Among them, the seam diameter has a greater impact on the effect of the seam. According to the results of the study, on-site practice was conducted, and the field data verified the numerical simulation results. The average tuning drilling has averaged gas flow for a routine drilling 1.4-2.2 times, the gas extract concentration is 3 to 4 times the conventional drilling, and the gas extract is 4.5 to 10.5 times the routine drilling. Provided by the theoretical basis for the determination of the parameters of the water-driven hydraulic cutting parameters.
- 1
Risk assessment of landslide hazards based on the IAHP-GRA modelAbstract:
Taking the landslide of Tibetan expressway as the research object, the indexes (percentage system) such as lithology grade, geological structure, slope structure, sliding body volume and sliding surface characteristics are selected. By constructing 100 point risk sequence and maximum risk sequence, the IAHP-GRA model is used for risk assessment. The results show that: 1) IAHP-GRA only needs to construct the most dangerous sequence, the process and calculation is simple, and the results are consistent with the fuzzy comprehensive evaluation of IAHP; 2) The discrimination of maximum dangerous sequence is 0.008, and the discrimination of the 100 dangerous sequence is 0.002. the maximum dangerous sequence has better discrimination than the 100 dangerous sequence; 3) When the risk levels of disaster points are the same, the fuzzy comprehensive evaluation of IAHP can not distinguish the risk relationship of disaster points. IAHP-GRA can make up for this defect and provide reference for local project site selection and route selection.
- 1
Numerical simulation of mechanical characteristics of sandstones with en echelon boreholesAbstract:
Borehole pressure relief method is a commonly used safety control method for high pressure release of rock materials in underground excavation works such as mining. To better understand the failure behavior of rock materials,the numerical simulation of uniaxial compression test of sandstones with en echelon boreholes is carried out by using ABAQUS software. Based on the calculation results of sandstones stress-strain curves, the influence of geometric layout of boreholes (the angle of rows of boreholes, the number of rows of boreholes and the diameter of boreholes) on sandstones compressive strength is analyzed. The numerical results show that compared with intact sandstone, the peak stress of sandstone with en echelon boreholes is significantly reduced, and the reduction range is closely related to the layout form of boreholes; With the increase of the angle of rows of boreholes, the failure trend gradually changes from axial splitting failure to sliding shear failure along the boreholes arrangement direction, then translated into axial splitting failure; The peak stress first decreases and then increases, which is the smallest when the angle of rows of boreholes is 60 °; With the increase of the number of rows of boreholes or the diameter of boreholes, the failure trend gradually changes from axial splitting failure to sliding shear failure along the direction of boreholes arrangement, and the peak stress decreases. The above research results will help to deepen the understanding of the borehole pressure relief method and provide guidance for the safe excavation of underground engineering.
- 1
Stability control strategy of rescue hoist under whole road surfaceAbstract:
Abstract:In order to study the steering stability of the all-ground rescue elevator in emergency rescue, Trucksim software was used to establish the vehicle dynamics model, and Matlab/Simulink was used to establish the active yaw control model of the rescue elevator. The yaw velocity - time relationship was analyzed under the three typical working conditions of single shift line, snake and step. The effectiveness of active yaw control is verified. The stability control ability of the three working conditions is compared and studied. The results show that the rescue hoist can meet the requirement of single line shift. However, the peak values are reduced by 40% and 28.6% respectively in the snaking and step steering conditions, indicating that the active yaw control strategy can effectively improve the stability of the rescue elevator when turning on the whole surface. These analysis results can provide reference for the design and optimization of the steering stability of the rescue elevator.
- 1
Study on pillar mining scheme based on three-dimensional laser goaf scanningAbstract:
with the continuous exploitation of mineral resources, there are a large number of irregularly shaped goafs in the underground mining of dongtangzi lead-zinc mine, and with the further mining of deep ore body, the goaf area continues to expand, resulting in great difficulties in pillar mining. Aiming at pillar mining under such complex conditions, based on three-dimensional laser goaf scanning, this paper puts forward different pillar mining schemes for different types of pillars. The field test shows that the proposed scheme can effectively solve the problems faced by pillar mining in dongtangzi lead-zinc mine, with a total mining volume of 73783.4 tons and a profit of about 51.2131 million yuan, creating a certain economic value for the mine, Ensure the sustainable development of the mine.
- 1
Effects of Red Mud Types on Grinding Characteristics of Co-reduction Products of Laterite Nickel Ore and Red MudAbstract:
This paper studies the grindability of the co-reduction products and the characteristics of the particles of the grinding products obtained by roasting two kinds of Bayer process red mud with low-grade laterite nickel ore at different temperatures and ratios. The results show that, the reduction temperature increases, the grindability of the co-reduction products of the the unprocessed red mud and pre-enriched red mud are reduced, the iron enrichment in the +0.045mm particle size of the co-reduction product of the grinding product becomes obvious, and the particles of this size in the grinding products gradually become larger. The proportion of red mud increases, the grindability of the co-reduction product of the unprocessed red mud increases first and then decreases, the degree of iron enrichment in the +0.045mm particle size of the co-reduction product of the grinding product first decreases and then rises, and the particles of this size in the grinding product change first grow bigger after small, single iron particles appear and the number gradually increases. The grindability of the co-reduction product of the pre-concentrated red mud is increased, the degree of iron enrichment in the +0.045mm particle size of the co-reduction product of the grinding product decreased significantly, and the particles of this size in the grinding product gradually became smaller.
- 1
Influence of Gobi Filling Body Strength Based on Response Surface Analysis Factor studyAbstract:
For the Gobi filling mine, in order to determine the optimal strength ratio test scheme of the filling body, taking Jinlonggou mine as the research object, based on the indoor strength and fluidity test of the filling body, the test design range of the three factors of the cement-sand ratio, slurry concentration and fly ash ratio was determined, and 17 groups of test schemes were designed by response surface analysis method. The influence law of the three factors and their interaction on the strength of the Gobi filling body was studied. At the same time, the response surface regression model between the three factors and the strength of the Gobi filling body at the curing age of 3 days, 7 days and 28 days was established, and the material ratio of the Gobi filling slurry in the Jinlonggou mining area was optimized. The results show that the cement-sand ratio is the biggest factor affecting the strength of Gobi filling body ; under the interaction of three factors, the degree of influence on the strength of Gobi filling body is as follows : ash sand ratio and slurry concentration > ash sand ratio and fly ash > slurry concentration and fly ash. Under the condition of satisfying the filling strength, the optimal ratio of filling slurry of Gobi material in Jinlonggou mining area is 1:8 of cement-sand ratio, 82 % of slurry concentration and 10 % of fly ash.
- 1
Application of pre-charges explosive technology in West No.2 Mining Area of Longshou MineAbstract:
In the process of sublevel caving mining in the West No.2 mining area of Longshou Mine, the front row of hole blasting often causes serious damage to therear row of hole , which results in the rear hole blasting being unable to charge normally, the ore loss and dilution, hanging roof and push-wall accidents are frequent, which seriously affect the normal production of the mine. This paper analyzes and studies the internal mechanism of the serious damage to the rear row holes, and obtains that the reason why the rear row holes are seriously damaged by the blasting of the front row holes, it is caused by the intrinsic characteristics of broken ore and the special mining technology of sublevel caving in the West No.2 mining area. It is difficult to solve the problem completely by simply optimizing the blasting parameters. According to the actual situation of the West No.2 mining area, the technical scheme of pre-charges explosive is put forward, that is, before the blasting of the front row of holes, the charge of the rear row of holes is completed, and the corresponding safety measures are worked out, the scheme has been applied in the field. The production practice shows that the technical scheme of pre-charges explosive proposed in this paper has successfully solved the problem of the difficulty of hole charging under the condition of broken ore in the West No.2 mining area, and has greatly increased the ore recovery index and productivity, the scheme is not only simple operation, high efficiency, good safety, but also easy to be popularized. It has reference and guiding significance for similar mines.
- 1
Analysis of Influencing Factors of Surface Subsidence in Double Coal Seam MiningAbstract:
The surface subsidence caused by coal mining seriously affects the ecological environment of mining area, compared with single coal seam mining, the surface subsidence caused by double coal seam mining is more compl- icated. In order to study the influence law of different factors on the surface subsidence of double coal seam minin-g, based on the measured data of surface movement in different mining areas, the influence of bedrock thickness, l- oose layer thickness, mining height of upper and lower coal seam and coal seam spacing on the surface subsidence are studied by using the methods of grey correlation analysis, theoretical analysis and similar simulation experiment.The results show that the bedrock thickness and the loose layer thickness have the greatest influence on the surface subsidence, followed by the mining height of the upper coal seam and the coal seam spacing, and the mining hei- ght of the lower coal seam has the least influence. Considering the difference of geological conditions and the inter-action of various factors in each mining area, the variation law of surface subsidence is studied by taking the basemining ratio, base-load ratio and inter-mining ratio as the key parameters, it is found that the surface subsidence co-efficient of single coal seam mining decreases with the increase of base-load ratio and base-mining ratio, and the s-urface subsidence coefficient of double coal seam mining decreases with the increase of the three key parameters. T-he similarity simulation results are consistent with the theoretical analysis results, which indicates that the research r-esults are reliable. It has important reference significance for the study of surface subsidence law under similar min-ing conditions.
- 1
Effect of cooling temperature on meso fracture of granite under thermal shockAbstract:
From the meso point of view, with the help of high-precision micro CT technology and based on the construction of three-dimensional spatial digital core, the meso evolution process of granite heated to the same temperature and rapidly cooled to different temperatures in the same cooling medium is studied, and the factors of fracture length, width and depth of granite after thermal shock are analyzed in detail, The effect of cooling temperature on the meso properties of granite under high temperature thermal shock was studied. The results show that the thermal shock of granite changes obviously with the increase of its cooling temperature in water. When the cooling temperature in water is 100 ℃, the thermal fracture of granite is the most severe. This shows that in the process of thermal shock fracture of granite, the fracture degree is related not only to the initial heating temperature of granite, but also to the temperature of rapid cooling in water. In addition, the pore fracture network generated after thermal fracture of granite will greatly improve the compactness of granite, and then help to increase the heat exchange area in geothermal development and reservoir reconstruction.
- 1
RESEARCH ON THE CHARACTERISTICS AND CONTROL METHODS OF WATER INFLOW IN DEEP VERTICAL SHAFT OF METAL MINEAbstract:
Due to water seepage, the deep shaft construction is difficult to carry out. The seepage flow formula of shaft in different construction layers was established by constructing the wellbore seepage model. Taking the deep shaft of Shaling Gold Mine in the Shandong province as the engineering background, the water inflow characteristics of shaft in different depths were analyzed. The influence of water pressure and permeability on wellbore water inflow under separate control and joint control were studied. The results show that with the increase of wellbore depth, the cumulative water inflow of wellbore increases nonlinearly and rapidly, and the cumulative water inflow of 1000m is close to 30 m3/h. which has completely failed to meet the construction requirements. To ensure the normal construction of 1500 m wellbore, the surrounding rock water pressure must remain constant below 300 meters, or the permeability of surrounding rock must be reduced to 1/7 of the original value. From the perspective of construction cost and technology, the joint control measures of water pressure and permeability is an effective measure to control wellbore water inflow. The study provided reference value for the development of shaft construction and long-term service stability of shaft.
- 1
Study on rock mass collapse early warning based on single channel event ratio of microseismic monitoringAbstract:
Abstract: In view of the technical difficulty and low accuracy of relying on location event analysis in the early warning application of mine microseismic monitoring technology,this paper discusses the feasibility of using single channel event number and single parameter index to realize the early warning of ground pressure appearance caused by local stress concentration, and introduces the concept of single channel event ratio,that is, the ratio of the event rate under abnormal conditions to the event rate under normal conditions,based on different single channel event rates in various regions.Considering the impact of initial construction disturbance, the single channel event rate,as an early warning index, is dynamically adjusted to make the early warning more suit to field conditions.In practical application.The multiple ratio of single channel early warning is 3. In the actual monitoring process, the multiple ratio of single channel event reaches 6.75. Rock mass slope collapse occurs after early warning. Further analysis shows that,The results show that when the single channel event ratio exceeds the early warning ratio, it indicates that the stability of surrounding rock continues to deteriorate. After this deterioration process lasts for a period of time, the rock mass will have macro cracking and collapse. This single channel microseismic monitoring and prediction method can find the internal change law of rock mass in time and can be more easily applied in the field monitoring process,allowing a certain early warning processing time to avoid risks and better realize effective monitoring.
- 1
Effect of low rank coal surface oxygen-containing functional groups on slime flotationAbstract:
The poor flotation effect of low rank coal is an urgent problem to be solved.In order to promote the efficient utilization of low-rank coal, two kinds of low-rank coal and two kinds of collectors were taken as the research objects, and the characteristics of low-rank coal surface were analyzed by means of SEM-EDS, FTIR and XPS tests, and the properties of different collectors and their effects on the surface of low-rank coal were studied, which were verified by slime flotation test.The results show that the surface of low-rank coal is rough and fissured, and is rich in oxygen elements, and oxygen elements mainly occur on the surface of low-rank coal in the form of functional groups. In addition, the higher the roughness, the more oxygen-containing functional groups, the less conducive to flotation.The molecular structure and chemical composition of the collector itself largely determine the flotation effect of slime. The collector with rich unsaturated fatty acid content is more likely to form weak hydrogen bond with oxygen-containing functional groups on the surface of low-rank coal, so as to improve the hydrophobicity of low-rank coal surface and achieve better flotation effect.In order to improve the quality of low order slime flotation, flotation agents suitable for slime surface properties should be developed.
- 1
Research on traversal path planning method for deep-sea mining vehiclesAbstract:
A full-coverage path planning method for deep-sea traversing mining operations is proposed to address the problems of lack of information about the surrounding environment, low real-time data processing capability, difficult and complex environment modeling, and difficulty in completing deep-sea mining operations autonomously and efficiently under complex conditions of the seafloor. Firstly, a 3D static map model of the seafloor is constructed by using the underwater DEM (Digital Elevation Model) data model obtained from the AUV (Autonomous Underwater Robot) data collection, and a 2D static raster environment model is constructed by dividing the obstacles according to the obtained substrate type data; then a heuristic function is established considering the raster state, distance factor and steering factor to realize the traversing path mining work. Combined with the mining dead zone problem that occurs in the actual mining process, the improved A* algorithm is introduced to plan the escape from the dead zone path to ensure the repetition rate is as small as possible. Finally, the verification results through MATLAB simulation show that the algorithm ensures the mining coverage rate of 100% while reducing the repetition rate and the number of turns, which improves the efficiency and economic benefits of the deep-sea mining vehicle and provides a theoretical basis for the deep-sea mining vehicle subsea path planning.
- 1
Optimization Research and Industrial Application of Copper and Molybdenum Separation Flotation Reagent system in a Porphyry Copper Mine in YunnanAbstract:
A large-scale porphyry copper mine in Yunnan uses a mixed flotation + copper-molybdenum separation flotation production process. Under the original design process and reagent system, there are some problems, such as large amount of sodium sulfide and sodium fluosilicate in the Copper-molybdenum separation flotation stage, high content of sulfide and fluoride in the separation flotation wastewater, and it is difficult to reuse and treat. By optimizing the original reagent regims through a lot of small-scale tests, the results show that the use of new depressor can obtain qualified molybdenum concentrate. In industrial application, the plant has continuously produced qualified molybdenum concentrate products. The grade of molybdenum concentrates is 46.43%, the recovery rate is 84.59%, and the cost of regent has been reduced from 19.733 RMB/ton of ore from the original design to 4.193 RMB/ton of ore, moreover the better economic effects were obtained.
- 1
Stability Analysis of Deep Mining in a Gypsum DepositAbstract:
A gypsum mine adopts room-and-pillar method for mining. A large area of goaf has been formed within the mining area, and there are villages within the mining area with dense population. In order to scientifically mine the deep resources below -400m and ensure the safety of surface structures, the stability of rock mass and its influence on surface deformation are analyzed by numerical simulation. the results show that After the stratified mining of ore body below -400m, the maximum deformation and vertical displacement of rock mass appear in the roof position, the overall deformation is small, and the subsidence or bottom drum phenomenon is not obvious; There is a regional compressive stress concentration in the pillar position, the maximum is 26.38 MPa. The tensile stress of the side wall of the mine room is small, not more than 2 MPa. There is no large stress concentration area and plastic breakthrough area in the whole; The maximum displacement of surface subsidence is 2.72mm, the maximum horizontal deformation is 0.003mm / m, the maximum tilt rate is 0.0091mm / m, and the maximum curvature is 6.74 * 10-5mm / m2. The results of each index show that the layered mining of ore bodies below-400m is generally stable, and has little impact on surface buildings and structures.
- 1
Influence of deep well mining environment on human functionAbstract:
With the increasing depth of coal mining, more high temperature and high humidity environments appear. By controlling the working environment, simulating the indoor temperature and relative humidity (the temperature is set at 28 ℃, 32 ℃, 34 ℃ and 36 ℃, and the relative humidity is set at 60%, 70% and 80%) and four labor intensities, the change laws of physiological and behavioral indexes are studied. The conclusions are as follows: in terms of physiological indexes, the temperature, humidity and labor intensity of working environment are directly proportional to each index; In terms of behavioral indicators, physical strength, responsiveness and attention are inversely proportional to ambient temperature, humidity and labor intensity. When the oral temperature reached 37.7 ℃ and the systolic blood pressure reached 148 mmHg, the subjects had obvious discomfort. When the ambient temperature is 28 ℃ and the relative humidity is 60%, the miners' reaction time and error rate are the lowest. Taking ambient temperature and humidity as independent variables and reaction time as dependent variables, multivariate nonlinear function fitting is carried out to obtain three function expressions with good fitting effect under moderate, severe and extremely heavy labor intensity.
- 1
Study on the influence of coal gangue powder on the properties of green cemented backfill based on coal gangueAbstract:
In view of a series of pollution problems caused by coal gangue discharge,the possibility of re pollution caused by the secondary transportation of fly ash,and the relatively high cost of gangue cemented filling with fly ash as admixture in remote mining areas；In this paper, the influence of gangue powder dosage on the performance, mechanical properties and water resistance of coal gangue-based green cemented backfill(CGGCFB)is studied by experimental study.The influence mechanism of coal gangue powder on the properties of backfill was analyzed by SEM and XRD. The results show that after simple mechanical activation,CGP can be used as an admixture in the coal gangue filling material,which can meet the requirements of the mine for pumping and transportation,and is suitable for the middle mass filling with relatively low strength requirements after filling at the bottom of the goaf. Give full play to the resource and regional advantages of coal gangue,make resource utilization of coal gangue from multiple angles and all directions,and reduce the mine filling cost,so as to provide a theoretical basis for the full application of coal gangue in mine green mining.
- 1
Optimization of Mining Approach Size after Mechanical Excavation Disturbance of Extremely Fractured Rock MassAbstract:
Considering the disturbance and damage effect of rock excavation on rock mass, the Hoek-Brown strength criterion based on rock mass wave velocity is introduced. Based on the indoor rock physical and mechanical parameters and acoustic test data, the relationship between wave velocity, GSI value and disturbance damage factor D was used to calculate the rock mechanical parameters of broken rock after mechanical excavation and unloading by cantilever tunneling machine. FLAC3D was used to simulate the failure phenomenon and failure form of mining approach under mechanical excavation with section sizes of 3m×3m, 4m×4m and 5m×5m. Combined with the mine production demand, the cantilever roadheader walking and turning requirements, numerical simulation analysis results and the safety of field implementation, the final recommendation of cantilever roadheader mechanical mining mining approach section size is 3.5m~4m width, 3.5m~4m height.
- 1
Development of Dynamic Performance Test Device for Mine Methane MeterAbstract:
Open laser methane meters are widely used in underground mines, and the response speed is greatly improved compared with traditional technology. However, the response time test for open laser methane meters under methane mutation conditions is temporarily blank. Through the research on the characteristics of the open laser methane meter, the multi-level transient technology is adopted to control the methane concentration gradient in the open environment. The multi-level open mine laser methane meter under the condition of the methane concentration transient is developed. The methane gradient dynamic switching time of the device can be adjusted in a wide range of 16ms～18s. The measurement accuracy is also improved.
- 1
DESIGN OF MINE DETECTION ROBOT AND RESEARCH ON DETECTIVE TRACKING ALGORITHMAbstract:
In order to solve the problems such as the poor tracking accuracy, overshoot, and weak robustness of the pan/tilt/zoom (PTZ) tracking system on the undermine detection robot, this paper designed and developed the mine detection robot and PTZ tracking system. Based on the robot with the PZT tracking system, the active disturbance rejection control (ADRC) algorithm for the PZT tracking system was developed to resolve the poor tracking accuracy, overshoot, and weak robustness problems. Considering the observation burden of the extended state observer (ESO) in the controller, the mechanism model between robot swing arm system and pitch attitude was modeled and studied. Therefore, the mechanism model was compensated as known information to the ESO for the proposed model compensation ADRC. Finally, the traditional proportion-integration-differentiation (PID) and standard ADRC were contrasted for the PTZ tracking system on the robot by the proposed MC-ADRC. The results show that the proposed algorithm is compared with traditional PID standards since the immunity control overshoot smaller volume adjustment time of the algorithm, and the external disturbance has more excellent interference resistance, greatly promoted the fast accurate robot target tracking. The results show that, the proposed MC-ADRC method has high speed control performance, shortened adjustment time and strong anti-interference ability, which is helpful to improve the target tracking and detection performances for the undermine robot.
- 1
STUDY ON DYNAMIC PROPAGATION LAW OF SYMMETRICAL CRACK UNDER IMPACT LOADAbstract:
In order to study the fracture mechanism of symmetric cracks in brittle materials such as rock under impact loading, the impact tests of PMMA specimens with symmetric cracks with different inclination angles were carried out by using digital laser dynamic caustics experimental system. The effect of inclination angle on the dynamic fracture behavior of symmetrical crack was studied, and the experiment was simulated by ABAQUS. The experimental results show that the propagation trajectory is affected by the initial crack inclination angle. When the inclination angle is 60 ° and 90 ° the crack propagation repels each other, and when the inclination angle is 120 ° and 150 ° the crack converges gradually during the propagation process. The change of SIF is affected by the change of inclination angle, and the crack initiation time decreases with the increase of dip angle. When the inclination angle is 90°, the difficulty of crack initiation is the least, and the strain energy at the crack tip is released gently. When the inclination angle is acute or obtuse, the crack initiation is more difficult and the energy release is faster. The numerical simulation shows that the maximum principal stress on the symmetry axis of the prefabricated crack is negatively correlated with the distance from the crack tip to this point, and the simulated crack propagation path is consistent with the experimental results.
- 1
Study on damage evolution of rock under freeze-thawAbstract:
Freezing and thawing has a significant impact on the stability of rock mass engineering in cold regions. In order to explore the law of rock damage evolution under freezing and thawing, this paper establishes a rock freezing and thawing damage coupling constitutive model considering the heterogeneity of rock mechanical parameters, and carries out the simulation of rock damage and fracture process under freezing and thawing. The simulation results intuitively reproduce the initiation and propagation of rock cracks under freezing and thawing Through the process, the results show that the freeze-thaw damage to the rock is an irreversible accumulation process from the outside to the inside, and reveals the stress field, deformation and damage evolution law of the rock under the freeze-thaw action. The model provides a certain reference for the prediction, early warning and disaster prevention of the landslide instability disaster under the freeze-thaw action.
- 1
Research on Surface Deformation of Shield Tunnel Under Crossing River in Silty ClayAbstract:
Relying on the background of the double-line shield tunnel underneath the outer city river of Suzhou Metro Line 6, combined with the on-site construction technology of the shield underneath the river, the ground surface displacement and segment deformation laws are studied with the help of Midas numerical simulation and on-site monitoring data. The emphasis is on the influence of grouting pressure and grouting material on the law of ground surface deformation during shield construction. Research indicates: During the excavation of the double-track tunnel, the surface uplift has a superimposing effect. The maximum uplift value reached 2.86 mm, which is about 1.5 times the maximum deformation of the single-track tunnel. The maximum horizontal displacement of the ground surface occurs on the upper left and upper right sides of the double-lane tunnel. The left and right line segments float up as a whole, and the maximum vertical displacement occurs at a lower position in the middle of the two tunnels. The deformation of the lower left side of the right line segment is obviously greater than that of the lower right side of the left line, but the deformations are roughly the same and distributed symmetrically. At the same time, the influence of different grouting parameters on the surface displacement is discussed, which provides a reference for the prediction of the surface displacement caused by the construction of the double-line shield tunnel underneath the river.
- 1
Experimental Study on the Fluidity and Mechanical Properties of Alkali-Excited Slag/Fly Ash SystemAbstract:
To address the problem of low strength and poor economic efficiency of the filling body caused by using cement as cementitious material in a gold mine, a new type of mine filling alkali-excited cementitious material was prepared by adding water glass as the excitation agent using local solid waste slag and fly ash as the main raw materials. With the help of orthogonal design test method, the effects of exciter dosing, exciter modulus, fly ash dosing and water-cement ratio on the fluidity and mechanical properties of slag/fly ash composite cementitious system were investigated. The test results show that: the amount of exciter is positively correlated with the flow and compressive strength of the slurry; the flow and compressive strength of the slurry increase from 1.0 to 1.5, and then decrease; in the cementitious system without fly ash, the flow of the slurry is poor, and with the increase of fly ash, the flow of the slurry increases and the compressive strength decreases; the water-cement ratio and the flow of the slurry are Positive relationship between the water-cement ratio and the slurry flow, with the increasing water-cement ratio, the compressive strength decreases rapidly and fluctuates widely. When the water-cement ratio is 0.30, the amount of exciter is 6%, the modulus of exciter is 1.2, and the amount of fly ash is 20%, the slurry flow is 164 mm, and the compressive strengths at 3 d, 7 d, and 28 d of curing are 2.15, 3.66, and 4.83 MPa, respectively, which meet the requirements of mine production.
- 1
INFLUENCE OF STRUCTURE PARAMETERS OF INCLINED OREPASS ON THE MOVEMENT CHARACTERISTICS OF ORE-ROCKAbstract:
In order to study the influence of ore-rock movement on wellbore stability in inclined orepass, based on the kinematic principle, the mechanical model of moving ore-rock under sliding state was constructed, and the influence of structure parameters of inclined orepass on the movement characteristics of ore-rock was studied. The functional relationship of the movement velocity of ore-rock sliding in inclined orepass was obtained, and the influence of the structural parameters of inclined orepass and sliding friction coefficient on the speed of the ore-rock was analyzed. It was found that the movement velocity of ore-rock in inclined orepass was relation to structural parameters of orepass, sliding friction force of ore-rock and force from other ore-rock blocks. The results show that:(1)When the sliding friction coefficient μ remains constant, the height h and the angle α Increased, the kinetic energy of gravity potential energy conversion of the ore-rock increases, and the ore-rock velocity also increases, reduce conversely; (2)When the orepass height h remains constant, as the decrease of the orepass angle α and the increase of the sliding friction coefficient μ, the kinetic energy of the gravity potential energy transformation of the ore-rock decreases, the ore-rock velocity is decrease, increased conversely; (3)The orepass height h, the sliding friction coefficient μ and the orepass angle α have the significant influence on the rock velocity V0, in which the orepass height h has the greatest influences and the orepass angle α has relatively little, but the orepass angle α also affects the movement direction of the ore-rock. On this basis, according to different design schemes of the inclined orepass, the measures and suggestions for controlling the ore-rock velocity V0 are put forward, so as to reduce the impact of ore-rock on the main orepass.
- 1
Research on Key Technology of Mining Gently Inclined Thick Orebody in Xiaodonggou MineAbstract:
Safe and efficient mining of gently inclined thick ore bodies is the main goal pursued by all the mines. This paper takes the slightly inclined and thick ore body of Xiaodonggou Mine as the research object, and uses three-dimensional geological modeling, ore rock stability classification, mining method design and other key techniques to carry out this research. Studies have shown that the cut and fill mining method can be adapted to the safe and efficient mining of the gently inclined thick ore body in Xiaodonggou Mine. The economic and technical indicators are: the production capacity of the stope is 160t/d; the ore loss rate is 4.53%, and the dilution rate is 4.1%. It provides a reliable reference for the mining of the same type of mines all around the world.
- 1
Research on local filling strengthening technology of pressure relief anchor layer in large diameter boreholeAbstract:
In order to solve the conflict between pressure relief of large-diameter borehole and deformation control of surrounding rock, precast concrete columns are used to strengthen the anchorage layer of large-diameter pressure relief borehole. Taking 3307 working face of Yiqiao coal mine as the research object, this paper studies the fracture development trend around the borehole before and after backfilling by using PFC2D numerical simulation software. The simulation results show that the development of rock fracture and the generation of penetrating main crack can be effectively restrained after borehole backfilling, and the number of cracks in surrounding rock around the borehole is reduced by 181% compared with that without backfilling. The field test results show that after borehole backfilling, the maximum approach of two sides of roadway is reduced by 112%, and the maximum approach of roof and floor is reduced by 32%.Drilling local backfill concrete can effectively slow down the deformation of roadway surrounding rock and improve the overall stability of surrounding rock.
- 1
Clustering algorithm based on density peaks to improve K-means dominant orientation grouping of rock discontinuityAbstract:
The discontinuities of rock masses control the stability of rock mass engineerings such as rock slopes and under-ground caverns, and play a key role in the engineering analysis and simulation calculation of rock mass mechanics. In order to correctly and effectively group the discontinuities of rock masses, a clustering algorithm based on densi-ty peaks to improve the K-means dominant orientation grouping of rock discontinuity is proposed, which makes up for the shortcomings of K-means random selection of clustering centers lead to easily fall into local optimum and instability. First, by calculating the local density of discontinuities of rock masses occurrence and the distance be-tween clustering centers, the initial clustering center and orphan value are accurately determined, and then use K-means algorithm for cluster analysis to obtain reasonable clustering results of dominant occurrences. Finally, the algorithm was applied to artificial simulation and the discontinuities of rock masses data in DIPS. The clustering results show that the improved K-means algorithm grouping based on density peak is reasonable and reliable, and it can effectively realize the discontinuities of rock masses grouping and the determination of dominant occurrences.
- 1
Experimental Study on Crack Induced Antireflection Technology of Liquid CO2 Phase Change in Coal SeamAbstract:
The antireflection technology of liquid CO2 phase change induced cracking coal seam can effectively solve the problems of poor permeability and low gas extraction rate of coal seam. This paper No.3 coal seam in Changzhi area as the engineering background，through the theoretical analysis is oriented crack extending three stages，the initial crack and fracture fissure zone radius，puckering are studied by using numerical simulation under different borehole spacing，porous and liquid CO2 phase change regularity of crack low permeability coal seam fracture，and industrial test was carried out. The results show that the maximum damage range of single-hole liquid CO2 phase change splitting blasting coal seam is 6m，and setting empty holes in the middle of blasting holes can expand the damage range of phase change splitting blasting，and can increase the spacing of blasting holes in porous liquid CO2 phase change splitting blasting coal seam to 7m. The engineering practice shows that the average gas extraction concentration of No.3 coal seam increases from 0.57% to 0.92%，the gas extraction rate of single hole increases 1.25~2.91 times，and the gas extraction rate is obviously improved after the implementation of liquid CO2 phase change cracking technology. This study provides theoretical basis and field guidance for antireflection technology of liquid CO2 phase change induced cracking coal seam.
- 1
EXPERIMENTAL ANALYSIS OF STRENGTH SPATIAL DISTRIBUTION CHARACTERISTICS OF BACKFILLAbstract:
Aiming at the spatial distribution of strength in tailing backfill bodies with different grading, a self-made filling model was used to study the spatial distribution of strength in tailing backfill bodies with different grading (full tailing, graded coarse tailing and graded fine tailing) along the horizontal and vertical directions. The results showed that the strength of cemented tailing backfill with different grading presents non-uniformity in the horizontal flow direction. It moved like a cosine curve around the strength of the standard specimen, and the fluctuation degree showed that graded coarse tailing backfill was greater than full tailing backfill, and the graded fine tailing backfill was the least. The strength of tailing with different grading along the horizontal direction was regressed and quantified by using the cubic multinomial formula; The strength of filling body increased with the increase of depth in the vertical direction. Compared with the increase of filling body strength,the graded coarse tailings filling body was greater than the full tailings filling body ,and the graded fine tailings filling body was the least.SEM and CT scanning were used to analyze the microstructure of filling bodies at different levels. It can be seen that in the horizontal direction of the filling stope, the early strength of the full tailings filling body differs greatly, while the early strength of the graded fine tailings filling body differs little.Backfilling materials in the vertical direction, the whole pack and grading in fine backfilling body gap filling quantity showed a trend of the gap down the less number of, all variations in backfilling body gap filling quantity is smaller, and the grading fine backfilling body gap filling quantity is relatively uniform, early strength gap filling body quantity is filling body is one of the important factors.The above is of guiding significance to design stope structure and filling point position.
- 1
Research of Solving the Track Section Poor Shunting Problem in Mining IndustriesAbstract:
The railway in the mining area undertakes the important task of transporting mineral resources. The current standpoint of “caring production capacity, neglecting transport safety” in mining industries is subject to the situation where there is rusty tracks, which is very easy to lead to poor shunting and even traffic accidents. According to statistics presided, there are more than 420 general Class D train accidents occurred in mining industries transport process every year. Based on this situation, the scheme of 3V reform for track circuit system has been proposed from the aspects of reforming objectives, requirements and key points, it has been proven that 3V reform is reliably to realize the shunting function of track circuit under the most unfavorable conditions, meets the signal discipline “fault oriented safety”, has no effect the functions of other by adopting several times field tests.
- 1
STUDY ON MECHANICAL PROPERTIES AND CRACK FRACTURE CHARACTERISTICS OF RED SANDSTONE UNDER DIFFERENT MORPHOLOGYAbstract:
In order to explore the changes in the mechanical properties of red sandstone under different forms and the development of crack and fracture forms, change the water content of red sandstone and prefabricate different forms of cracks, study the changes in its compressive strength under uniaxial compression, and use image processing to The generated cracks are analyzed and processed quantitatively, and the development characteristics of cracks and the different failure modes under different moisture content, different crack angles, and different crack lengths are studied. The study shows that the increase in moisture content under uniaxial compression makes the red sandstone specimens resistant to The compressive strength decreases and the crack morphology becomes more complicated; changing the prefabricated crack angle, the 0 ° specimen has a special crack development pattern that is different from other angles, and the 45 ° specimen has the lowest compressive strength and produces fewer branch cracks; specimens The longer the length of the prefabricated crack, the lower the compressive strength, the smaller the crack rate and the collapse area coefficient, and the faster the crack growth rate. The conclusions obtained from the experiment comprehensively record the changes of red sandstone crack morphology under different shapes, and provide a basis for further research on the development of red sandstone cracks.
- 1
RESEARCH OF DOWNWARD SINGLE-APPROACH CEMENTED FILLING METHOD FOR FRACTURED SURROUNDING AND ORE BODYAbstract:
In view of the steeply inclined thin ore body with extremely unstable ore and rock, a new downward single-approach cemented filling method is proposed. This method adopts the layout of in vein mining, and there is no pillar in the ore block. The mining method of single roadway approach is adopted, and the mining moves forward from both wings of the mine house to the center, and the collapsed ore is transported to the pedestrian ventilation patio by electric harrow to complete the ore drawing. After mining the layered ore body, super long anchor rods are constructed on the surrounding rocks of the upper and lower walls in the direction of vertical ore body, and are connected with the long anchor rods through reinforcement mesh. When all the ore in the stope is mined and the goaf is filled, the pedestrian ventilation patio on one side of the mine room shall be filled immediately, and the pedestrian ventilation patio on the other side shall be reserved for pedestrian, ventilation, material extraction and ore drawing during the mining of the adjacent mine room. Taking Qilishan mine of Canzhuang Gold ore as the engineering background, this mining method is compared with the downward drift slicing and backfilling without sublevel mining method. The research shows that the proposed new mining method is superior to the downward drift slicing and backfilling without sublevel mining method in terms of roadway layout, support and filling cost. The research results have important guiding significance for similar mines to realize safe and efficient mining.
- 1
Experimental Study on Beneficiation of a refractory zinc oxide oreAbstract:
In order to comprehensive recovery a refractory lead-zinc ore, the reverse flotation process was determined on the basis of exploratory test. The effects of grinding, dosage of inhibitors and collectors were investigated respectively. The closed circuit test results show that, with the feed containing 1.99% Zn, a good index of concentrate grade of 16.22% and Zn recovery of 76.29% was obtained with the reverse flotation process.
- 1
LABORATORIAL INVESTIGATION OF PARTICLE SIZE EFFECT ON FORWARD SMOLDERING PROPAGATE OF UNDERGROUND COALAbstract:
According to the characteristics of underground coal smoldering fire, the horizontal forward propagation of the smoldering process was investigated for three types (particle sizes) of coals (0.15-1.70 mm) with different ranks. The results show that with the reduction of particle size, the proportion of pores > 10 nm increases by 34.0%, the specific surface area increases by 30.0%, and the pore volume increases by 78.8%. which is responsible for strongly smoldering of coal. Different types of coal samples show four distinct combustion stages between 25.0℃ and 800.0℃. With the decrease of particle size, the activation energy for coal smoldering during the combustion weightlessness stage. decreases by 5.7%-16.1%. The critical minimum air-supply for smoldering coal is 0.13 m3h-1kg-1 to 0.20 m3h-1kg-1. Besides, the critical quantity increases with increasing particle size. The maximum smoldering temperatures peak at 427.0℃ to 489.7℃ for YN lignite, at 543.1℃ to 675℃ for SX anthracite, and at 608.0℃ to 696.0℃ for SX bituminous coal, the average smoldering spread rate increased in turn, which mainly affected by the char-oxidation temperature. The average peak smoldering-temperatures and average smoldering spread rate are negatively correlated with particle size.
- 1
Control Technology of Overburden Migration in Intelligent Backfilling Mining of Deep Coal SeamAbstract:
The coordinated development of safe and efficient deep coal mining and ecological environmental protection is an important theme of current green coal mining. Based on the geological production conditions in the deep coal seam of Yineng Coal Mine as the engineering background, the intelligent upgrading of backfilling mining equipment has been carried out in field, and set the remote control center in the roadway to realize intelligent backfilling mining. The working matching scheme of backfilling and mining is explored, and the reasonable backfilling and mining parameters are obtained. According to the production capacity of CG1304 working face, the pulping capacity required by single slurry theory is 104m3/h. In order to improve the control effect of overburden migration coordinated by backfilling and mining, the control technologies of overburden migration coordinated by mining and backfilling such as pipeline blockage prevention and secondary backfilling are put forward; The intelligent monitoring and early warning system of deep backfilling face and the evaluation strategy of backfilling mining effect are constructed, which provides a scientific basis for realizing the intelligent backfilling mining of deep coal seam and the effective control of overburden migration
- 1
Simulation study on resistance and wear analysis of tailingcemented filling slurry pipelineAbstract:
Using computational fluid dynamics numerical simulation software CFD, according to the actual layout of underground pipelines in a gold mine, following the laws of mass, energy and momentum conservation, a three-dimensional numerical calculation model of ANSYS is established. The cement-sand ratio of the filling slurry was set to be 1 : 5, and the concentration of the filling slurry was 68 %, 70 % and 72 %, respectively. The numerical simulation tests of the velocity, resistance and wear of the filling transportation pipeline were carried out. The results show that : 1 ) the maximum velocity in the straight pipe is located in the center of the pipe, and the maximum velocity in the elbow is located outside the pipe. 2 ) With the increase of slurry concentration, the pipeline resistance loss increases. When the filling slurry concentration was 70 %, the pipeline resistance loss reached 14.24 MPa. 3 ) With the increase of flow velocity, the erosion wear rate increases gradually, especially when the velocity is greater than 6m / s, the erosion wear rate increases sharply, and because of the inertial force, the erosion wear mainly occurs in the outer part of the pipeline, and the numerical simulation law is consistent with the actual field.
- 1
Experimental Study on Mineral Processing of a High-pelitic Copper OreAbstract:
The recovery rate of a copper ore is low due to its high mud content. The influence of reagent system on ore flotation is mainly studied. By optimizing the flotation environment, hydroxyethyl cellulose with significant inhibition effect on magnesium silicate gangue minerals and slime is used to realize the efficient separation of copper minerals and gangue minerals, and to reduce the amount of lime by 50%. The copper concentrate with copper grade of 15.73% and copper recovery of 80.78% in a low alkalinity environment was obtained.
- 1
SOFTWARE DEVELOPMENT AND APPLICATION OF ABUTMENT PRESSURE ESTIMATION IN DEEP WORKING FACEAbstract:
How to accurately and quickly grasp the distribution law of abutment pressure is of great significance for mining design. Based on the theoretical analysis, the static abutment pressure estimation models of working face in different motion states are established. The software of abutment pressure estimation is developed by C #, and the structure and application method of the software are introduced. Taking 1300 working face of a mine in Shandong province as an example, the lateral static abutment pressure of 1300 working face was estimated by the software. The field dynamic behavior was consistent with the calculation results, indicating that the software can effectively and conveniently estimate the distribution law of abutment pressure of deep working face.
- 1
The forecasting of tantalum resource demand based on the output of major industrial products in ChinaAbstract:
Tantalum is one of the important strategic emerging raw materials, the United States, the European Union and Japan have included it in the list of key mineral resources. China"s tantalum resource endowment is poor and its external dependence is high. Accurate forecast of tantalum resource demand of China in the future can provide reference for the global strategic layout of Tantalum resources in China. Due to the lack of consumption structure data of Tantalum resources in China and the fact that tantalum is not a major mineral resource, conventional demand forecasting methods such as departmental forecasting method and "S" type forecasting model cannot be applied. Starting from the perspective of industrial products at the next level of consumption structure, this paper conducts the stepwise regression analysis and modeling of tantalum resource consumption data and tantalum-related industrial product output data, and sets three growth assumptions for the future output of tantalum-related industrial products: baseline scenario, high growth scenario and low growth scenario. It is forecasted that the tantalum resource demand in 2025 in China is 869 tons, 938 tons and 1085 tons respectively in the base scenario, low growth scenario and high growth scenario. 823 tons, 1024 tons and 1,529 tons in 2035; The future demand trend will increase first and then decrease, with the peak between 2030 and 2035. The peak point in the base scenario is 2030, the low growth scenario is 2032, and the high growth scenario is 2034. Conclusion: 1) The demand for tantalum resources in China will be strong in the future; 2) In the future, Tantalum consumption in China will continue to rely on imports. 2) Tantalum resources in China will face fierce global competition in the future; The policy suggestions are as follows: 1) To improve tantalum smelting technology in China; 2) Pay attention to the recycling of secondary resources; 3) Strategic layout of global resources.
- 1
Multi-Objective Optimization of Wet Shotcrete Parameters Based on BP-NSGAⅡ ModelAbstract:
In order to obtain the optimal performance of wet shotcrete parameter design scheme, this paper proposes a multi-objective optimization model of wet shotcrete mixture parameters based on BP-NSGA ⅱ.Firstly, the collapse degree of wet shotcrete slurry and 28d uniaxial compressive strength of concrete were taken as objective functions, and cement content, water-cement ratio, sand-stone ratio and water-reducing agent content were taken as decision variables to establish the basic framework of the model.Then combined with the specific engineering requirements, the wet shotcrete mix ratio test was designed and carried out, and comprehensive and reliable wet shotcrete mix ratio and compressive strength test data were obtained.Secondly, the obtained data are preprocessed into training set and test set and used as input variables to train BP neural network.Finally, the trained BP neural network is integrated into a fitness function as a whole, and the Pareto optimal solution of the decision variables in the fitness function is obtained by the improved non-dominated genetic algorithm (NSGA ⅱ) according to the objective function. Finally, the optimal wet shotcrete mix ratio parameters that meet the C25 strength are as follows: water cement ratio: 0.53, cement content: 440kg/m3, sand to rock ratio: 8:2, water reducing agent content: 0.60%;The optimal mixing ratio of C30 is as follows: water cement ratio: 0.50, cement content: 460kg/m3, sand to rock ratio: 7:3, water reducing agent content: 0.65%;The optimal mixing ratio parameters of C35 are: water-cement ratio: 0.46, cement content: 480kg/m3, sand to rock ratio: 8:2, water reducing agent content: 0.63%。
- 1
STABILITY ANALYSIS OF STOPING STRUCTURE IN FULL LIFE CYCLE OF OPEN-PIT AND UNDERGROUND COOPERATIVE MININGAbstract:
Aiming at the structural stability analysis of open-pit - underground cooperative mining, numerical simulation method was selected to research. The concept of stability evaluation of collaborative mining structure in the whole life cycle was put forward. The influence of underground multi-method combined mining on the open-pit slope was analyzed, and the stability of underground mining structure in the whole life cycle was evaluated. The mechanical mechanism of safety isolation pillar between mining methods was verified. The results show that, it is more scientific to analyze the stability of stoping structure from the perspective of the whole life cycle of open-pit and underground cooperative mining. Isolation pillar can effectively block the harmful transfer of disturbance stress between different mining methods, and it is can maintain different stope structure stability. By setting reasonable mining scheme and mining sequence, the open-pit and underground mining can be realized simultaneously with multiple methods. It provides useful reference for similar mines to improve resource acquisition ability.
- 1
Stability Analysis and Treatment SchemeSof Landslide of Open Pit Mine SlopeAbstract:
In view of the slope failure of different degrees in Zhengguangyan open-pit gold mine in Heilongjiang Province, the reasons for the landslide were analyzed from the aspects of geological structure, rock mass quality, rainfall, the spatial relationship between slope surface and rock mass level, etc., and HDPE impermeable film was proposed to protect the slope for the loose soil sliding above 504m level.For bedding landslides and wedge-shaped landslides from 492m level to 504m level, long anchor cable reinforcement scheme is adopted.The numerical simulation software FLAC3D is used to simulate the slope reinforced with long anchor cable, and the stability of the slope reinforced with long anchor cable is analyzed theoretically. Based on the principle of strength reduction, the minimum safety factor of the slope is 1.5, which is greater than the failure factor of the slope 1.1, and the maximum displacement of the slope reinforced is only 4.3mm.The results show that the layered treatment method of HDPE impermeable film slope protection and long anchor cable reinforcement has good reinforcement effect on the unstable slope in the eastern zhengguangyan open-pit mine, and provides a reference scheme for slope landslide control in similar open-pit mines.
- 1
Application Research on Integrated Platform of Multi-source Information Integration and Security Management for Ultra Deep WellAbstract:
In response to the demand of safety centralized control of an ultra deep well, a set of 2D and 3D integrated platform of multi-source information integration was studied and constructed for quick inspection of production environment and potential safety hazards underground. Based on unity3d and with a kernel of Data Center, the platform constructed the underground real 3D scene, integrated the safety monitoring data caused by deep well rockburst, surrounding rock deformation, water inrush and other disasters into Data Center through data acquisition, database integration, visualized the data by the virtual reality technology, and realized the dynamic management of underground production safety. The applied results showed that the integrated platform can visualize the multi-source information such as geology, structure, hydrology, micro earthquake, surrounding rock deformation and on-site inspection of an ultra deep well, reduce the system maintenance personnel, remotely monitor the underground production status in the surface office, comprehensively analyze the influencing factors of production safety. It provided auxiliary support for safety management and rapid decision-making of ultra deep wells.
- 1
STUDY ON PROCESS CONDITIONS OF SYNERGISTIC LEACHING OF PHOSPHORUS CONCENTRATE WITH SULFUR AND PHOSPHORUS MIXED ACIDAbstract:
In this paper, the influences of various factors (including the concentration of sulfuric acid and phosphoric acid, temperature, sulfuric acid excess coefficient, leaching time, liquid-solid ratio, and particle size) on the leaching ratio of phosphorus concentrate are studied systemically by mixture of sulfuric acid and phosphoric acid. The results show that appropriate technological conditions are as follows: concentration of sulfuric acid was 15%, concentration of phosphoric acid was 15%, temperature of reaction was 55℃, leaching time was 60 min, liquid-solid ratio was 12, and particle size was <38 μm. Under appropriate technological conditions, more than 96% of phosphorus can be leached out. The influencing degree of every factor and optimum conditions of leaching were analyzed by using orthogonal experimental method. The results indicate that liquid-solid ratio was the most influencial factor to the leaching process, followed by leaching time and temperature. The maximum leaching rate of phosphorus was up to 98.88% on optimum leaching conditions.
- 1
STUDY ON PHYSICAL AND MECHANICAL PROPERTIES OF SOIL MASS IN HEAP LEACHING SITE OF ION RARE EARTH MINEAbstract:
Mining ionic rare earths by heap leaching requires open-pit mining, which will cause a lot of damage to the plants and soil on the surface of the mine, so that the soil is completely exposed, after being washed by Rain Water, it is easy to occur geological disasters such as soil erosion and landslides, and the soil type is also gradually changed to sandy soil. Taking the ionic rare earth mine at Datangwei heap leaching site in Dingnan County as the study area, the physical and mechanical properties of waste slag soil at the heap leaching site were studied, and the soil moisture content was carried out respectively. Physical and mechanical tests such as density, liquid-plastic limit and direct shear test. In order to further clarify the change law of soil shear strength and its index under different moisture content conditions, five different gradient conditions of soil moisture content of 9%, 12%, 15%, 18% and 21% were set to prepare remolded disturbed soil samples. the direct shear test was carried out in the laboratory. The test results show that with the increase of moisture content gradient, the cohesion of soil samples increases at first and then decreases, and the internal friction angle fluctuates in "w" shape, and the shear deformation resistance of soil samples decreases gradually, and so does the shear strength. The results can provide a theoretical basis for ecological restoration and management of this kind of sites.
- 1
Simulation study on spatial structure evolution characteristics of hard overburden coal seam miningAbstract:
Under the condition of hard overburden, the fracture and dynamic evolution of hard roof slab of working face are easy to lead to strong ground pressure behavior. Taking menkeqing coal mine as the background, through the similar simulation test, this paper deeply understands and analyzes the evolution characteristics of mining spatial structure of hard overburden coal seam, so as to provide a theoretical basis for ensuring the safe mining of coal seam. The results show that the first weighting step of low-level hard overburden is 60m and the periodic weighting step is 20 ~ 30m. The overburden structure gradually evolves from short masonry beam structure to F-shaped cantilever beam structure on both sides of goaf. The first weighting step medium and high-level hard overburden is 130m and the periodic weighting step is 50 ~ 80m, The overburden structure gradually evolved from long masonry beam structure to F-shaped cantilever beam structure on both sides of goaf together with low-level hard overburden; The variation area of longitudinal displacement of hard overburden gradually increases, the displacement increment in the middle of goaf is greater than that at both ends, and the maximum subsidence of roof is 5.69m, which is located in the middle of goaf; The synergistic effect of "large period weighting" of medium and high hard overburden and "small period weighting" of low hard overburden leads to strong ground pressure in the working face, which seriously affects the safe mining of the working face. The research results have certain theoretical guiding significance for the safe mining of the working face under similar conditions.
- 1
Fluidity and regression analysis of paste with polypropylene fiberAbstract:
Incorporating polypropylene fiber into the paste can effectively improve the compressive strength and post-peak toughness of the filling. However, the resistance of the paste pipe will be seriously affected with the complex relationship between the fluidity and the material properties of polypropylene fiber paste. In this paper, the unclassified tailings and rod-mill sand of a mine are used as experimental materials to study the influence of polypropylene fiber content and length on the fluidity of paste. The regression models of slump and expansion of paste with the fiber content and length is obtained, and economic cost of the polypropylene fiber paste is calculated. The results show that slump and expansion decrease with the increase of the polypropylene fiber length and content. The length and content of polypropylene fiber basically have a negative linear relationship with the slump, and the relationship between polypropylene fiber content and expansion is basically negative exponential function. The order of influencing slump and expansion are fiber content and fiber length, and expansion is more affected by polypropylene fiber length and content than slump. Compared with unincorporated polypropylene fiber, the slump of fiber decreased by 0.77% ~ 5.02%, the expansion of fiber decreased by 3.70% ~ 36.54%, and the cost of polypropylene fiber paste increased by 2.95 ~ 15.61%. Finally, the regression models of fiber content and fiber length were established, and regression effect is significant.
- 1
(1. National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Jiangsu 221116, China; 2. School of Chemical Engineering and Technology, China University of Mining and Technology, Jiangsu 221116, China;)Abstract:
In order to explore the interaction mechanism between the functional groups in the collector and the surface of low rank coal slime, the properties of low rank coal and collector were explored by means of industrial analysis, elemental analysis, XRD, SEM-EDS, surface tensiometer and FTIR. The interaction mechanism between low rank coal and collector was characterized by means of X-ray photoelectron spectroscopy (XPS) and dynamic contact angle test analysis. The effects of diesel oil, gutter oil, peanut oil and compound collector DH32 on the flotation performance of low rank coal were compared through flotation test. The results show that under the same dosage of reagent, the flotation performance of gutter oil and peanut oil are obviously better than that of traditional hydrocarbon oil collector diesel. On this basis, the compound reagent DH32 can further improve the recovery of combustible matter of clean coal. This is because DH32 contains a large number of oxygen-containing functional groups compared with diesel, which is easy to produce electrostatic and hydrogen bonding with the polar sites on the surface of low rank coal molecules. A large number of hydrophobic groups (C-C / C-H) are attached to the surface of coal sample, which greatly enhances the hydrophobicity of coal sample, so as to achieve better flotation performance.
- 1
Study on activity optimization of smelting slag and low costcementing agentAbstract:
A vanadium-titanium magnetite will produce granular or massive blast furnace slag after blast furnace smelting, and a new type of industrial titanium slag can be obtained by using chlorination method to extract titanium resources. In order to explore the feasibility of preparing new binders from smelting slag, the flexural and compressive strength tests of blast furnace slag and titanium slag were carried out. The strength development law of titanium slag-full tailings filling test block was explored by using cement, quicklime as activator and active agent. The results show that : 1) The activity of blast furnace slag is poor, and the activity of titanium slag reaches 78 % after 28 days, which has the condition of being used as cementing agent. 2) The excitation effect of quicklime on titanium extractant is not good. When cement is used and the proportion of titanium slag is 60 %, the strength of 3 days is 12.78 % higher than that of pure cement, and the strength of 7 days is equivalent. It indicates that when the proportion of titanium slag powder to cement is less than 60 %, the same strength or higher strength can be achieved under the same proportion.
- 1
Research on Influencing Factors and Proportion Optimization of Full Tailings Filling Materials in a Gold MineAbstract:
In order to explore the influence of various factors of the filling material on the compressive strength of the filling body, the optimal grading tailings and filling ratio of the mine were determined. Four tailings from a gold mine tailing pond in Shandong are selected as experimental materials, and the influencing factors are designed as tailings size, ash-sand ratio, slurry mass fraction, and the response index is L16 (43) orthogonal to the compressive strength of the backfill. Experiments, through range analysis, variance analysis and regression analysis, determine the law of influence of each influencing factor on the compressive strength of the filling body, and determine the optimal grading tailings and the optimal ratio. The results show that after analyzing the chemical composition and particle size distribution, it is determined that the four tailings can be used as filling materials, but the theoretical analysis and experimental results show that the 3# tailings is the most suitable as the filling material for downhole filling; compressive strength The experimental results, range analysis and variance analysis all prove that the sensitivity of the influence of various factors on the strength and compressive performance of the backfill is as follows: slurry mass fraction, ash-sand ratio, tailings grade; 3# tailings 3d, 7d, 28d linear regression Equation, the multiple correlation coefficient R2 is greater than 0.95, the average error is 0.76%<2%, and the prediction accuracy is high. It is recommended that the filling ratio of 3# tailings, lime-sand ratio of 1:6, and slurry mass fraction of 70 is satisfied. Filling requirements for gold mines.
- 1
An economic evaluation method for open pit mining planAbstract:
For the problem of deviation in the quantitative evaluation results of the economic evaluation for open pit mining planning caused by the difficulty of accurate and fine calculation of transportation distance, this paper proposes an economic evaluation method for open pit mining plan. The basic idea is as follows. Combining with the current situation of the mine, the open pit mining object is discrete to form the open pit mine value model. According to the transport road, the transport distance of each value block is calculated. Each economic parameter of the economic evaluation is obtained, and then the economic evaluation model is constructed. By solving this model, the economic evaluation results are obtained. The method meets the requirements of the economic evaluation of the open pit mining plan, and accurately and finely considers the influence of the transportation distance on the economic value. The scientificity and feasibility of the economic evaluation results are improved for the open pit mining plan.
- 1
Exploration and practical research on the “clean mine” transfer system of mining rights——Take Shandong Province as an exampleAbstract:
The transfer of "net mine" is a major innovation in China"s mining rights transfer system. This article combines the spirit of the national mineral resources management reform and summarizes the practical experience of Shandong Province in promoting the transfer of "net mine" pilot work, and analyzes Pingyi County, Linyi City The typical case of Fengshan mining area explained the main highlights and key links, and summarized the experience and practice of "five in place", namely, the transaction procedures are in place, the policy services are in place, the ownership investigation is in place, the department coordination is in place, and the performance supervision is in place. The “clean mine” transfer system model was established, the main work flow was determined, and the main meaning and specific standards of “net mine” transfer were clarified, which further enriched the connotation of “net mine” transfer.
- 1
Prediction Of The Uniaxial Compressive Strength Of Rocks Based On Stacking Ensemble AlgorithmAbstract:
Uniaxial compressive strength is one of the most widely used mechanical parameters in rock engineering. Traditional uniaxial compressive strength test of rock is expensive, time-consuming, and has certain limitations. In order to accurately and quickly determine the uniaxial compressive strength of rock, a prediction method based on the Stacking ensemble algorithm is proposed. Based on the porosity (n), P-wave velocity (Vp), Schmidt hammer rebound number (Rn), point load index (Is(50)) and 7 types of base model including Polynomial Regression and RidgeCV, combined with Stacking integrated learning algorithm to build a prediction model of uniaxial compressive strength. The model was verified through 290 data sets, and the empirical model was used for comparative analysis. R2 of the empirical model were less than zero and RMSE were 64 to 84; R2 of the basic learning model were between 0.74 and 0.81 and RMSE were between 23 and 28; R2 and RMSE of stacking integration model were 0.88 and 18.49, respectively. Results indicated that the integration model outperformed all other models, and the prediction of the uniaxial compressive strength of rocks based on Stacking ensemble algorithm has a better prediction effect.
- 1
Experimental Study on Mechanical Properties of Limestone Similar MaterialsAbstract:
Limestone is widely distributed and is a common rock species in engineering construction. In response to the need for limestone similar model test, the cement plaster material was used to conduct experimental research on limestone similar materials. The conditional setting of similar material tests includes: three cement-gypsum ratios 3: 7, 5: 5, 7: 3, three kinds of sand-binder ratios 3:1, 4:1, 5:1, and three water-solid ratios 1: 6, 1.1: 6, 1.2: 6, a total of 27 matching. Single-axis compression test, Brazilian split test, straight shear test, and Hopkins test were carried out to measure mechanical performance parameters such as compressive strength, tensile strength, cohesive strength, intrusion angle, elastic modulus, poisson ratio and dynamic compressive strength of different similar materials,. Based on the test data, the effect of the mechanical strength of water-solid ratio, sand-binder ratio, and cement-gypsum ratio on cement gypsum similar material was analyzed. Combined with the measured limestone mechanics parameters, the ratio of the similar model test applied.
- 1
Research on the influence of crushed stone and fiber on the strength of fine-grained tailings packingAbstract:
Aiming at the optimization of the strength of the fine-grained tailings backfilling body, explore the influence of adding different crushing fineness gravel and different length polypropylene fibers on the strength performance of fine-grained tailings backfilling body.The results show that the addition of crushed stone is beneficial to the improvement of the strength of the backfilling body, and the particle size composition and addition ratio of the crushed stone are the key factors,among them, 2#-unclassified crushed stone is used, and the strength of the backfilling body is the best when the mass ratio of crushed stone tailings is 1:10, 3d, 7d, 14d, 28d uniaxial compressive strength increased by 1.47 times, 1.94 times, 1.91 times, 1.85 times, respectively,the yield stress of the filler slurry is reduced by 47.86%, and the plastic viscosity is reduced by 25%,correspondingly.The addition of fiber is beneficial to improve the uniaxial compressive strength, bending strength and direct shear strength of the backfilling body,the addition amount should be between 0.2% and 0.6%,the improvement effect of 18mm polypropylene fiber on the strength and integrity of the backfilling body is better than that of 6mm fiber,in the test, the 7d uniaxial compressive strength, bending strength, and direct shear strength of the filling body can be increased by 15.36%, 24.91%, and 29.49% respectively.The addition of fibers is beneficial to increase the residual strength of the filling body after the peak, which enables the filling body to ensure better overall stability when under pressure.The research results have reference significance for the optimization of the backfill strength when using fine-grained tailings in gold mines.
- 1
BASED ON TREENET ALGORITHM COAL AND GAS OUTBURST PREDICTION MODELCONSTRUCTION RESEARCHAbstract:
In view of the problem that a large amount of outburst omen information is not fully utilized in the implementation of outburst prevention measures in coal and gas outburst mines, and it is difficult to guide coal mines to carry out effective outburst prediction, a construction method of coal and gas outburst prediction model based on treenet algorithm is proposed. In this method, the cart algorithm is used to construct the test sample space of prominent omen engineering information, and the treenet algorithm of step-by-step iterative approximation is used to establish the classified prediction model. Through the algorithm, the important prediction variables in the test samples are found. At the same time, the contribution attribution of the prediction variables to the target variables is analyzed, and the most dangerous interval of the value of the prediction index is obtained, The sensitive index system of mine outburst prediction is constructed. By testing and analyzing the outburst data of yuanlimin coal mine over the years, it is found that the firmness coefficient, the maximum drilling cuttings and gas emission have an obvious corresponding relationship with the occurrence of outburst, which can be used as a sensitive index for the prediction of coal and gas outburst in this mine. The results show that the construction of coal and gas outburst prediction model based on treenet algorithm is a sensitivity discrimination method of working face prediction indexes based on machine learning, which can be used to establish the sensitive index system of working face outburst prediction in coal mines.
- 1
Study on the mining technology of cutting the roof and relieving the pressure along the goaf in Shuguang Coal MineAbstract:
In order to improve the theoretical and technical system of cutting roof, pressure relief and roadway retention, this paper analyzes the mechanism of cutting roof pressure relief and roadway retention along the goaf, combined with geological conditions and used theoretical formulas to design cutting joint parameters, and divide the cutting joint height into A, B, C In area, the height of cut joints in area A and C is 10m, the height of cut joints in area B is 11m, and the cut angle is 15°. The effect of the cut is simulated and analyzed by FLAC3D numerical simulation software. The results show that the overall surrounding rock stress of the roadway after the cut The environment is optimized, the difficulty of surrounding rock control is reduced, and the deformation of the roadway is reduced. The displacement of the empty side of the roadway roof surface is reduced by 40cm, which significantly reduces the control difficulty of temporary support after the reserved roadway is framed, which is conducive to the formation of the reserved roadway .
- 1
Study on automatic picking method of acoustic emission full waveform in coal rock testAbstract:
According to the characteristics of acoustic emission signal in coal experiments, an automatic acoustic emission waveform picking method is proposed.Through the uniaxial compression test method of coal rock, AE signal data in the whole process of loading was collected, and characteristics of AE waveform signal were analyzed. STA/LTA method (Long and short window energy ratio method) was used to pick up waveform to time point and waveform end point. Characteristic functions were introduced, and parameters such as long time window, short time window, ratio function value and gradient were set.The acoustic emission waveform can be picked up automatically in the whole loading process.The results show that :1) the acoustic emission signals of coal rock test show different characteristics at different loading stages.The rising time and duration of the pre-peak acoustic emission waveform are shorter, while the rising time and duration of the post-peak acoustic emission waveform are slightly longer.In the pre-peak elastic stage, the rising direction of acoustic emission waveform is mostly positive, while in the pre-peak plastic stage and post-peak stage, the rising direction of acoustic emission waveform is mostly negative.2) It can basically realize automatic picking of acoustic emission full waveform, and the picking effect is better than manual picking.
- 1
Study On Enhanced Flotation Mechanism Of Fine Low Rank Coal By New Composite CollectorAbstract:
The surface of low-rank coal contains rich oxygen-containing functional groups and developed pores. When re-cover low-rank coal by flotation with traditional non-polar hydrocarbon oil, the reagent consumption is large and the recovery rate of combustible part is low. To solve these problems, a new composite reagent DK1 was prepared by compounding diesel, fatty acids and their esters in a certain proportion, and its effect on the flotation of low-rank coal was investigated. By measuring the contact angle, induction time and critical detachment force be-tween particles and bubbles, the mechanism of strengthening the flotation of low-rank coal with a new composite collector was revealed. The results show that under the same dosage, the combustible recovery of the new compo-site collector is 2 ~ 4 times than that of diesel, and the ash content of cleaned coal is generally 1 ~ 4 percentage points lower than that of diesel. The contact angle of coal sample treated with the new composite collector is larger, the induction time is significantly shortened to less than 10 ms, and the action range and size of particle bubble jump-in attachment force and critical detachment force are increased in varying degrees. The diesel oil of DK1 has a synergistic effect with the active substances to effectively cover the surface of low-rank coal, thus significantly improve the floatability of low-rank coal and reduce reagent consumption. The dosage of DK1 is only 1/8 that of diesel oil.
- 1
Design and Reaearch of Integrated Control System for Deep Sea MiningAbstract:
Integrated control system is the top level control system of deep sea mining ship, which involves the integrated monitoring and intelligent cooperative control of multiple mining systems. This paper conducts in-depth analysis, design and research on the integrated control system of deep sea mining from the aspects of system functional framework, basic process of mining operation, cooperative operation rules and strategies, dispatch and command model, and proposes the overall plan of the integrated control system and the coordinated control, dispatch and command strategy. The rational dispatching and allocation of mining resources are realized based on particle swarm optimization-genetic algorithm (PSOGA), which provides a solid theoretical basis for the development of deep-sea mining integrated control system.
- 1
Extraction method and application of geometric properties of slop rock discontinuities based on 3D point cloudAbstract:
The spatial distribution of structural planes determines the stability of the rock mass. In order to solve the problem that traditional structural plane surveys have high risks and low efficiency, and general intelligent identification methods are not suitable for the development of fractured areas of structural planes, based on the three-dimensional laser point cloud data, it is proposed An accurate and simple method for extracting structural planes and obtaining information about their occurrence is presented. First, based on the local neighborhood entropy function minimum criterion, the point cloud principal component analysis algorithm is improved to obtain the point cloud normal vector information; then, the area growth algorithm is used to analyze the angle and curvature threshold of the point cloud normal vector, and the structural plane is identified ; Finally, obtain the structural plane occurrence information through the normal vector coordinate transformation and group it. Taking a certain fractured rock mass of Huangzang Temple in Qinghai as an example, the field identification test has been carried out. The results show that the method can accurately and easily extract the occurrence information of rock mass structural planes.
- 1
Experimental Study on Effect of Acidification on Coal WettabilityAbstract:
In order to study the influence mechanism of acidification on coal wettability, hydrofluoric acid was selected to acidify the test coal samples. The evolution of mineral composition and chemical structure was analyzed by X-ray diffraction ( XRD ) and Fourier transform infrared spectroscopy ( FTIR ). The wettability of the test coal samples was characterized by contact angle measurement and surface tension calculation. The results show that acidification can effectively dissolve minerals in coal, in which carbonate minerals are completely dissolved and silicate mineral content is reduced by 24. 4 %. Acidification can change the structure of functional groups on coal surface. The content of oxygen-containing functional groups and hydroxyl groups increased by 55.8 % and 10.4 %, respectively. The content of aromatic structure decreased by 17.9 %, and the content of aliphatic structure changed little. Through the contact angle test, it is found that the coal-water contact angle of the test coal sample after acidification decreases, the surface tension increases, and the hydrophilicity increases, which confirms the correctness of the above test results. Increasing hydrophilicity of test coal samples can promote gas desorption, which provides a theoretical basis for efficient exploitation of coalbed methane
- 1
Response Law of Radon Exhalation Rate from Beach Surface of Uranium Tailings Pond under the Effect of Earthquake-rainfallAbstract:
Part of the uranium tailings pond in southern China is located in the overlapping area of humid climate and potential earthquake. The influence of multiple natural disasters on radon exhalation from the beach surface of uranium tailings pond can not be ignored. A 1.0m×1.0m×0.8m simulated beach surface model of uranium tailings was made by selecting uranium tailings samples from a uranium tailings pond in southern China. A self-designed measuring device for radon exhalation was used to explore the variation rule of radon exhalation rate on the beach surface of uranium tailings pond under the action of earthquake-rainfall. The test results show that, under certain conditions of simulated earthquake peak acceleration, with increase of simulated rainfall, the development and expansion of surface cracks in the red soil overburden become more and more obvious; the radon exhalation rate on the surface of the overburden shows a trend of first decreasing and then increasing. When the simulated rainfall is reach the lowest at moderate rain (12.5mm/24h); according to the Grey Relational Analysis, rainfall has a greater impact on surface radon exhalation rate than earthquake peak acceleration. For this reason, it is more important to reasonably design the flood drainage system of the uranium tailings pond and strictly implement the beach flood control measures.
- 1
CFD Simulation of Geometric Parameters of Rotary Triboelectrostatic ChargerAbstract:
The rotary triboelectrostatic charger is the core component of a rotary triboelectrostatic separator. Its performance determines the separation efficiency of the electrostatic separator to a great extent. In order to investigate the influence of geometric parameters of the rotary triboelectrostatic charger on the charging effect of fly ash, a standard k-ε turbulence model combined with particle trajectory model was used to simulate the motion characteristics of particles with eight different designs of the rotary triboelectrostatic charger shape with spherical carbon and ash particles of 20、40 and 60 ?m diameter. The results have shown that when the number of sides of the cross section of the rotating friction wheel is twelve and inner concave arcs and straight lines are alternately distributed, the accumulation of particles on the lower right side of the friction charger is reduced significantly. It also increases the maximum rate of particles by at least 3.56% compared with the case where the cross section is circular. At the same time, the collision area between particles and friction wheel is at least 2 times higher than that when the cross section is circular. Thus, the collision friction is more sufficient and the friction electrification effect of fly ash particles is better.
- 1
Study on mechanism and treatment scheme of multi-step landslide in open pitAbstract:
In order to study the mechanism of multi-bench landslide in open-pit slope, based on an open-pit slope landslide, the cause of landslide, slope failure type and mechanism are analyzed, and the stability of landslide is analyzed by numerical simulation method. According to the mechanism research results and norms, the landslide control scheme is formulated. The results show that: (1) the landslide is mainly caused by rock fragmentation, steep slope angle, developed joint structure and poor drainage at the top of slope. (2) The slope failure type is collapse-displacement landslide, which is caused by the collapse of the first bench on top leading to the sliding of the slope from the second bench to the fourth bench beneath. (3) The safety factor of the landslide is less than the allowable safety factor, and the landslide is in an unstable state. (4) Slope cutting and load reduction treatment scheme can eliminate the hidden danger of landslide safety. The slope cutting parameters are as follows: the slope cutting range is above 1389m elevation; the overall slope angle is 40°; the width of a safety platform is 4m; the width of a cleaning platform is 14m.; the overall slope angle is 33 °. The conclusion provided a basis for the design and construction of mine slope landslide control and achieved good results.
- 1
Research on Mechanism and Control of Floor Heave of Mining Roadway in Fully Mechanized Mining Face with Deep Buried and Large Mining HeightAbstract:
The stability of the surrounding rock is the key problem regarding the normal use of coal mine roadways, and the floor heave of roadways is one of the key factors that can restrict high-yield and high-efficiency mining. Based on the 232204 auxiliary transportation roadway geological conditions in the Meihuajing Coal Mine, Ningxia, the mechanism of roadway floor heave was studied by field geological investigation, theoretical analysis, and numerical simulation. We think that the surrounding rock of the roadway presents asymmetrical shrinkage under the original support condition, and it is the extrusion flow type floor heave. The bottom without support and influence of mining are the important causes of floor heave. Therefore, the optimal support scheme is proposed and verified. The results show that the maximum damage depth of the roadway floor is 3.2 m, and the damage depth of the floor of roadway ribs is 3.05 m. The floor heave was decreased from 1150 mm to 350 mm, and the force of the rib bolts was reduced from 309 kN to 128 kN after using the optimization supporting scheme. This scheme effectively alleviated the "squeeze" effect of the two ribs on the soft rock floor, and the surrounding rock system achieves long-term stability after optimized support. This provides scientific guidance for field safe mining.
- 1
Research and Practice of Cost Refinement Management in Lead-zinc MinesAbstract:
Using refined thinking and management means, to effectively reduce the full cost of products, this is crucial to the improvement of the company"s viability. Taking mining enterprises as an example, from the three dimensions of management level, cost composition, production process and value chain, establish a cost target system centered on "complete cost".Build a cost refinement management system from the aspects of prospecting, strictly controlling the unit cost of outsourcing, improving the key indicators of beneficiation recovery rate, streamlining personnel, reducing procurement costs, strengthening scientific and technological innovation, strengthening investment management and performance appraisal. The results show that the resource reserves increase steadily, the beneficiation recovery rate increases year by year, and the labor productivity increases continuously. the unit complete cost of lead concentrate is reduced by 16.35%, and the unit complete cost of zinc concentrate is reduced by 20.12%. The research results have a good reference and reference significance for the cost fine management of domestic lead-zinc mines.
- 1
Experimental study on sandstone degradation under freeze-thaw cyclesAbstract:
To research from two aspects of macro and micro degradation characteristics of sandstone under the effect of freezing and thawing cycle, select new blue sandstone WuSu mining area in Inner Mongolia as the test material, specimen is divided into three groups, respectively, to 10, 30, 40 times freeze-thaw cycling test, adopt the method of binarization and nuclear magnetic resonance (NMR) to its appearance, quality rate, pore rate change, and nuclear magnetic resonance T2 spectrum analysis. The test results show that with the increase of the number of freezing-thawing cycles from 10 to 40, the deterioration degree of specimen appearance deepens. With more freezing-thawing cycles, water absorption, mass change rate and pore change rate also increase, but the pore change rate tends to be stable eventually. The pores of green sandstone coexist with both large and small pores. With the increase of freeze-thaw cycles, the number of small pores in green sandstone decreases while the number of large pores increases significantly.
- 1
ENERGY CONSUMPTION CHARACTERISTICS OF MAGNETITE QUARTZITE RADIATED BY MICROWAVE UNDWE ACTICE CONFINING PERSSUREAbstract:
In order to explore the energy dissipation law of microwave-assisted rock breakage in deep mining, the magnetite quartzite was taken as the research object, and the cyclic impact test under different confining pressures was carried out by combining microwave irradiation with SHPB with confining pressure device, and the energy dissipation characteristics of specimens irradiated by different microwave parameters were analyzed. The results showed that compared with the sample without microwave radiation, the wave impedance of the sample after microwave damage fluctuated greatly under the interaction of confining pressure and impact pressure, which resulted in the measured value discreteness of impact times and energy ratio of the sample under microwave parameter M1 at 2MPa, 4MPa and M2 at 6MPa, respectively; by analyzing the relationship between specific energy and cumulative specific energy and impact times, it was found that the energy utilization rate of M1 and M2 specimens without microwave radiation and under different microwave parameters was the best under confining pressure of 6MPa, 6MPa and 4MPa; the dissipation energy of the specimen irradiated by microwave was far less than that of the specimen not irradiated by microwave, and the P wave velocity of the specimen irradiated by 2 microwave parameters was inversely proportional to its energy consumption. In the practical application of microwave-assisted rock breakage, appropriate microwave parameters should be selected.
- 1
Experimental Research and Calculation on Parameters of Drilling Whirling of the Deepsea Core-sampling DrillAbstract:
The vortex problem of deepsea core-sampling drill in the process of drilling operation are studied, and the vortex model of deepsea core-sampling drill string was put forward. Drilling dynamic model with fluid was built basing on the dynamic pressure bearing model，and the relationship between drill pipe eccentricity distance and whirling angular through numerical analysis. The drilling speed threshold Ωmin was introduced and verified by laboratory experiment. Experimental results show that under the same experimental conditions, when the deepsea core-sampling drilling speed close to theory threshold point, the core-sampling result and quality can be better, which verifies the rationality of the theoretical calculation result and provides references for developing the deepsea core-sampling drill and core-sampling drilling operation subsequently.
- 1
Experimental Study on Active Anchorage Mechanism of Prestressed Anchor Cable in Inclined Bedded Rock MassAbstract:
Roadways with inclined bedding roofs usually have obvious asymmetric failure characteristics, and its stability control is a complicated problem for roadway support. Research on the anchoring mechanism of bedding rock masses is helpful to determine the support parameters reasonably. This paper uses similar simulation tests to study the anchoring control mechanism of bedding rock masses under different anchoring angles and prestress conditions. The results show that the anchor cable pre-stress can effectively restrain the crack expansion of bedding rock mass, and the restraining effect becomes more obvious with the increase of the axial restraint load of the anchor cable. The peak strength of the anchor solid increases by 96.97% compared with that without anchor. The strength of the anchoring structure of the physical rock mass maintains a slow-increasing trend, the rock mass swelling deformation can be effectively controlled, and the residual strength is increased by 148.33%; the anchoring angle has a significant impact on the rock mass reinforcement effect. The anchoring angle of 90° has an elastic modulus, The peak strength and residual strength are increased by 59.33%, 34.34% and 96.67%, respectively. When the anchoring angle is 45°, the anchoring angle is increased by 16.71%, 14.29% and 18.64% compared with the anchoring angle of 90°; Relatedly, when the prestress is increased from 0.5kN to 0.7kN, the elastic modulus, peak strength and residual strength of the specimen are increased by 66.14%, 46.62%, and 26.27% respectively, that is, increasing the anchor cable prestress can effectively improve the overall anchoring strength of the specimen; When the vertical displacement of the test piece is constant, with the optimization of the anchoring angle and the increase of the prestress, the restraint effect of the anchor cable on the expansion of the rock mass is enhanced.
- 1
Analysis of Green Technology Innovation Efficiency and Influencing Factors in Mining EnterprisesAbstract:
In this paper, the DEA model is used to measure the green technology innovation efficiency of China's mining enterprises above scale from 2011 to 2018, and the comparative analysis is made from the two aspects of green technology R&D efficiency and green technology achievement transformation efficiency.The Tobit model is used to conduct regression test on the influencing factors. The results show that the improvement of green technology innovation efficiency is attributed to technological progress; Enterprise size, equity ratio, market openness and resource recycling level are significantly correlated with enterprise green technology innovation efficiency. To improve the efficiency of green technology innovation in mining enterprises, it is necessary to strengthen industry exchanges and learning, strengthen R&D investment, and improve the policy system of green development of enterprises.
- 1
Research progress of oxidation/low-rank coal flotation reagents and feasibility of reductants flotationAbstract:
With the decreasing reserves of high-quality coal resources in China, it is imperative to upgrade the quality and comprehensive utilization of oxidized/low-rank coal. Surface oxidation is the main cause of poor floatability of oxidized/low-rank coals. The oxygen-containing functional groups on the surface of oxidized/low-rank coal can easily form hydrogen bonds with H2O, which makes the hydrophobic organic matter covered by hydration layer and reduces the floatability of coal. The difficult floatation problem of oxidized/low rank coal can be improved by improving reagent system, selecting flotation method, or pretreating the coal. Selection of suitable flotation reagents is the most commonly used method, which can obviously improve coal surface hydrophobicity and improve slime flotation efficiency. Compared with traditional agents, reductants can reduce oxygen-containing functional groups to hydrocarbons. Theoretically, this method can be used to reduce the oxygen-containing functional groups on the surface of oxidized/low-rank coal, fundamentally solve the problem of the oxide layer, thereby effectively improving the flotation efficiency. This method has high application potential and broad application prospect to carry out in-depth research.
- 1
Study on the Flow Characteristics and Pipeline Transport Resistance of High Concentration Filling Slurry in Sanshandao Gold MineAbstract:
Due to the long filling distance, high filling times line and concentration, the slurry is difficult to be transported in the Xiling mining area of Sanshandao gold mine. By conducting rheological, L-pipe self-flow and semi-industrial pressurized looping pipe tests, the flow characteristics and the pipeline transportation resistance of high concentration filling slurry in the mine were studied. The results show that: the filling slurry reaches the paste state at a concentration of 74% ~ 76% and the cement sand ratio of 1:4; the L-pipe self-flow test shows that as the slurry concentration increases, the yield stress, plastic viscosity and flow resistance of the slurry increase significantly and the times line of transmission decreases, while as the cement sand ratio decreases, the yield stress of the slurry decreases and the plastic viscosity increases, but the flow resistance decreases, resulting in an increase in the slurry flow rate and the times line of transmission. The transportation resistance of the filling slurry along the pipeline is related to the yield stress, plastic viscosity, transportation velocity and diameter of transportation pipeline. Through semi-industrial pressurized looping pipe tests, the pressure loss of the pipe is positively related to the cement sand ratio, concentration and pumping flow velocity, and the pressure loss of the pipeline is the highest at the cement sand ratio of 1:4, the slurry concentration of 76% and the maximum flow rate (around 1.5m/s), with a straight pipeline pressure loss of 4.324Pa/s; the best pumping conditions for the mine can be selected according to the pressure loss in the pipeline under different cement sand ratio, slurry concentration and pumping flow rate conditions, and combined with the strength requirements of the backfill on site.
- 1
Automatic Plan Preparation Method under Ring Advance Mining and Stripping Model for Open Pit MineAbstract:
In view of the problems of difficult to control the fluctuation of ore quality, unreasonable mining quantity and imbalance of stripping ratio caused by the complicated calculation process, cumbersome operation and low real time of open pit mining plan preparation, this paper proposes an automatic plan preparation method under ring advance mining and stripping model for open pit mine. The basic ideas are as followed. Combine the current situation of the mine, set the mining plan target under the ring advance stripping mode and specify the location of the starting point of the ring advance, establish a mathematical model for automatic preparation of the mining plan under the ring advance stripping mode, and obtain the plan results by solving the model. The method meets the requirements of automatic preparation of open pit mining plan under ring advance mining and stripping mode under time, space and process constraints. At the same time, the planning results meet the requirements of quality fluctuation, mining quantity and stripping ratio, which ensures the continuous balanced production and cost-effective operation for the open pit.
- 1
REASEARCH ON RHEOLOGICAL PROPERTIES OF WHOLE TAILINGS PASTE FILLING SLURRY IN A MINEAbstract:
Aiming at the problem of large transport resistance of a lead-zinc ore filling pipeline over long distances, the rheological properties of the paste filling slurry were measured with the RST-SST rheometer,and it was revealed that the mass fraction, sand-lime ratio and hydration time had a significant effect on the rheological parameters of sand paste filling slurry. The test results show that the whole tailings paste of a mine belongs to Bingham fluid;the yield stress and plastic viscosity of the whole tailings paste are the most sensitive to the mass fraction, followed by the sand-lime ratio and hydration time; The rheological parameters of the whole tailings paste increase with the mass fraction in a quadratic function, decrease linearly with the sand-lime ratio, and increase linearly with the hydration time; When the mass fraction of the slurry is between 74% ~77%, the sand-lime ratio and hydration time have little effect on the rheological parameters. When the mass fraction is between 77%~80%, the sand-lime ratio and hydration time have Greater impact on the rheological parameters, when the sand-lime ratio and hydration time are respectively 4~7, 60~100min or 8~10, 120~140min, the rheological parameters are small and the change is not significant. When the sand-lime ratio and hydration time are respectively 4~7 , 120~140min or 8~10, 60~100min, the rheological parameters are relatively large and change significantly.
- 1
Study on the optimization of non-equilibrium grade multi-metal and multi-objective ore blending in ShizhuyuanAbstract:
Based on the mining and selection process of the underground open-pit collaborative mining of Shizhuyuan, this research starts from, the optimization of ore grade, mining recovery rate, production capacity, and mining and transportation costs etc, constructing a multi-metal and multi-objective refinement ore optimization model. With the help of MATLAB software, an adaptive genetic algorithm is used to solve the model. Based on the production operation plan of Shizhuyuan in August 2020, the results show that the multi-metal and multi-objective refined ore optimization model can be used for the preparation of short-term production operation plans for underground open-pit collaborative mining; The result obtained by the ideal point method can well balance the relationship between ore grade, production capacity, mining and transportation costs and recovery rate, and has certain guiding significance for improving the economic benefits of enterprises.
- 1
STUDY ON THE INFLUENCE OF OVERLYING BULK CHANGE ON THE STABILITY OF SURROUNDING ROCK OF COLLAPSE PITAbstract:
In the caving mining of metal mines, the loose body formed by caving ore and rock in the collapse pit has an important influence on the support of surrounding rock and the stress state and movement of surrounding rock mass. Combined with the actual mining situation of Chengchao Iron Mine, the combination of similarity simulation test and PFC numerical simulation is used to select typical sections to study the influence of the change of overburden dispersion in the collapse pit on the stability of footwall surrounding rock. The results show that: 1) the change of loose body directly leads to the redistribution of horizontal stress in the footwall surrounding rock, and the whole shows a gradually decreasing trend, which is more obvious in the area closer to the surface; 2) From the strain value and change trend, the main influence of the change of overlying loose body in the collapse pit on the footwall surrounding rock is the horizontal movement and deformation of the surrounding rock, and the closer it is to the collapse pit, the more obvious this influence is numerically reflected; 3) With the gradual transfer of the ore body mining area to the hanging wall, the vertical deformation of the footwall surrounding rock tends to be gentle. The research results reveal the influence of the change of overlying caving rock mass on the movement law of surrounding rock in the footwall of the ore body, and provide a reference for the safety maintenance of important surface structures and buildings and the formulation of corresponding measures for the next mining in Chengchao iron mine.
- 1
Prediction for Blasting Fragmentation of Rocks Using Improved Random Forest Regression MethodAbstract:
In order to improve the prediction effect of rock blasting fragmentation, the study used the rock blasting data from several mines in the world to build a blasting fragmentation prediction model based on the improved random forest regression (RFR). The model was applied with six characteristic variables including the specific charge (Pf), the rock block size (XB), the elasticity modulus (E) and the ratio of hole plug length to row spacing (T/B) that were selected as input parameters through the importance calculation and Pearson correlation coefficient determination. The fragmentation sizes predicted by this model were closed to the real value. For the prediction results of this model, the determination coefficient (R2), the root mean square error (RMSE) and the mean relative error (MRE) were 0.9881, 0.0430 and 0.1445, respectively. Compared with the model of linear regression and BP neural network, the RFR model created better results. Therefore, the RFR model was more applicable in practice and can provide a reference for the design and optimization of blasting construction parameters.
- 1
Study on the Mechanism of “Supporting-Yielding” of Supporting BodyBeside High Strength Yielding in Gob-Side EntryAbstract:
In order to solve the problem that the existing filling material can"t adapt to the roof movement in the process of gob-side entry under the condition of high stress in deep well, On the basis of C40 concrete, high ductility concrete with strain coefficient of 2%～10% was obtained by orthogonal test with EVA polymer and steel fiber. Taking the 21213 working face ventilation entry of Maidizhang Coal Mine as the engineering research object, the supporting effect of modified concrete filling body with different strain coefficients is studied by combining theoretical analysis and numerical simulation. Research shows: (1) Based on the elastic foundation theory and masonry beam theory, the modified concrete with a strain coefficient of 5.6% can make the key block turn to contact gangue, and the maximum support force required by the filling body is 20.46 MPa. (2) Numerical analysis results show that with the increase of strain coefficient of filling body, the maximum vertical stress ratio between filling body side and solid coal side decreases from 1.32 to 0.34, and the stress concentration position gradually shifts from filling body side to solid coal side, and filling body plays a role of yielding support. However, if the strain coefficient is too large, the supporting stress of the filling body is insufficient, and the subsidence speed of the roof is too large, which is not conducive to the control of the surrounding rock of retaining roadway. Based on the above analysis results, In engineering practice, Concrete with strain coefficient of 6% should be used as the filling wall in the ventilation entry of 21213 working face. While adapting to the given deformation of the roof, it has high enough strength to make the basic roof turn and sink smoothly.
- 1
Study on surrounding rock stability of tunnel with fissure zone based on FLAC3DAbstract:
Taking the No. 1 inclined shaft of Xinglong Tunnel in Yunnan as the engineering background, aiming at the problem of the influence of the finite length fissure zone on the stability of the tunnel surrounding rock, FLAC3D numerical simulation was used to analyze the influence law of the fissure zone with different dip angle and width on the vertical displacement of the surrounding rock, and perform quantitative evaluation. The results show that: 1) As the angle between the fissure zone and the centerline increases, the maximum vertical displacement during the excavation of the upper and lower steps is approximately the same. The vertical displacement reaches the maximum at an angle of 30°, but the difference of the maximum vertical displacement increases gradually; 2) With the angle increases, the affected area gradually changes from the vicinity of the fissure zone to a large area of surrounding rock above the tunnel, and the shape gradually changes from triangle to hat shape. The area increases first and then decreases, and the maximum area is 62.70m2; 3) As the width of the 0°angle fissure zone increases, the vertical displacement first increases rapidly, and then flattens out, while the area of the affected area increases linearly; 4) The increment of vertical displacement and the size of the influence area are proposed to quantify the influence of the fissure zone on the surrounding rock of the tunnel, which can comprehensively consider the local instability and large-scale deformation caused by the fissure zone.
- 1
Seismic Failure Process Analysis of Cataclastic Rock Landslide in Plateau Gradient ZoneAbstract:
For the problem of deformation and failure of cataclastic rock slopes induced by earthquake in plateau gradient zone, UDEC software was used to numerically simulate the failure of cataclastic rock slopes under the action of 45°oblique incidence of seismic waves.The results show that the deformation and failure of slopes can be divided into 3 stages, under the action of seismic waves, cracks are first generated and developed at the top of the slope, the upper rock mass of the slope was damaged by the structural surface cutting and local sliding began to occur. With the formation of the controlled structural surface, the overall stability of the slope decreased rapidly, the falling rocks on the slope form an accumulation body, and the sliding area gradually expands to the middle and lower part of the slope, until the instability is destroyed; The impact area of the ground motion load on the slope can be divided into the failure area and the damage area, the dynamic response of the failure area to the earthquake is greater than the damage area; Meanwhile, the larger the slope angle and structural plane inclination, the more serious the slope deformation and failure.
- 1
Evaluation of slope stability of open-pit mine by fuzzy comprehensive evaluation method based on two-level analysisAbstract:
In order to comprehensively evaluate the slope stability of open-pit mine in the process of production, the fuzzy mathematics evaluation model of two-level analysis is used to evaluate the slope stability. Taking fully into account the engineering geology, geometric conditions, hydrology and meteorology, applied load and other factors that affect the slope stability of open-pit mine, a two-level evaluation index system is established, consisting of 14 sub-indexes. Considering the trend characteristics of the influence of different sub-indexes on the slope stability of open-pit mine, the weight set and membership fuzzy matrix of corresponding indexes are established, and the fuzzy comprehensive evaluation set based on the two-level analysis is constructed, and the evaluation results of slope stability degree are given. The results show that the fuzzy evaluation method based on the two-level analytic hierarchy is simple and practical, and the evaluation results are consistent with the actual situation, which can provide guidance and help for the slope stability evaluation of open-pit mine with numerous influencing factors and frequent production blasting.
- 1
Study on floor heave characteristics and anchor pile control of roadway with high stress soft floorAbstract:
Floor Heave often appears in soft rock roadway, especially under the influence of mining and tectonic stress. In this paper, 3313 extraction roadway in Shuangliu mine is taken as the engineering background, the mechanism of roadway floor heave and its stability control countermeasures are studied by means of analytical analysis, numerical simulation and engineering application. The analysis shows that tectonic stress increases the horizontal stress of the surrounding rock by 2.1 times, and the mining influence increases the vertical stress by 2.1~3.5 times, which results in 2.45~2.91 times of the failure force of the bottom heave of the roadway Based on this, an optimization scheme of floor heave control is put forward, which can reduce the vertical stress of the side by adding two side cable anchors and reduce the horizontal stress of the floor by adding steel sheet piles at the bottom, the results show that the vertical stress of the two sides can be reduced by 15.1% and the horizontal stress of the floor by 18.3% with the increase of the bottom steel sheet pile, the roadway floor heave is reduced by 73.1% , and the plastic failure area is reduced by 61.5% , thus achieving the overall stability of the roadway. Through the practical application in the new driving and drawing roadway in Shuangliu Mine, the good field application effect is obtained, which provides a scientific basis for the roadway support in the high stress area with soft floor.
- 1
STUDY ON FLOTATION PROCESS OF A SILICATE FLOURITE IN HENANAbstract:
A fluorite ore in Henan province contains CaF2 33.8%, CaCO3 4% and SiO2 44.52%, which belongs to high silica type fluorite ore. On the basis of mineral technology, a series of beneficiation experiments have been carried out according to the characteristics of ore in this mining area. Under the conditions of grinding fineness of -0.074mm 70%, pulp pH neutral, sodium oleate as collector and mixed inhibitor S-824, the final fluorite concentrate with CaF2 grade of 97.57% and recovery of 90.23% was obtained, and the high efficiency separation of fluorite and quartz was realized.
- 1
Comparative Study on Compensation Models of Gas Loss in Positive Pressure and Countercurrent Sampling MethodsAbstract:
In order to improve the calculation accuracy of gas loss compensation in the determination of coal seam gas content, 10 representative coal samples taken from a positive pressure countercurrent flow in a mine in Hancheng, Shaanxi were selected as the research object, and five commonly used gas loss compensation calculation models were selected and the three proposed the square model is used to fit the correlation coefficient R2, MSE (Mean Square Error), MAE (Mean Absolute Error), and the amount of lost gas under the test of different coal samples, different desorption durations, different coal seam gas pressures and different desorption pressures. As a judgment index, the results show that: the desorption pressure is below 0.6MPa, the minimum value of the logarithmic fitting correlation coefficient R2 is 0.997, and the degree of fit is relatively high. The maximum value of NMSE and NMAE is 11.96 and 2.36, and the relative minimum of has the highest stability and accuracy, the relative error and the maximum absolute error of the lost gas amount are -10.78%, and the 22.23 is relatively minimum. It can be selected as the optimal compensation calculation model for the positive pressure countercurrent lost gas amount; similarly, above 0.6MPa, the cubic model is stable and with the highest accuracy, it can be selected as the best lost gas compensation calculation model.
- 1
Numerical simulation of dust in tailings pondAbstract:
Tailings pond is an essential facility for mine production. Tailings piled in tailings pond will produce dust under the action of wind erosion, which will seriously affect the environment of reservoir area. Through ANSYS Fluent numerical simulation software, the wind speed and wind pressure state of air flow passing through the tailings pond, as well as the change of dust concentration and height on dry beach surface are simulated, and the dust law of tailings pond is analyzed. The results show that the wind speed changes greatly when the airflow passes through the convex part of the dam body, and the increase of wind speed there is about 43%.It can be seen from the airflow pressure cloud diagram that the pressure varies greatly at the convex change of the dam body shape. In the case of forward blowing erosion, the wind pressure changes from positive pressure to negative pressure at the convex change of the dam body top. The change of wind speed and wind pressure means that the tailings particles are more likely to loosen and produce dust. It can be seen from the dust concentration distribution on the dry beach surface that the tailings pond dust is mainly distributed at 10-30m on the dry beach surface. With the increase of wind speed, the dust concentration and space height gradually increase. In conclusion, during dam construction, it is suggested to pave gravel for slope protection in time, plant grass on slope, and spray water or dust suppressant on dry beach surface in time to suppress tailings pond dust.
- 1
Modification and application of RMR method of rock mass quality classificationAbstract:
In order to make the evaluation more objective and scientific, in order to make the evaluation more objective and scientific, in order to make the evaluation more objective and scientific, the various indicators of the RMR method have been studied; the rock strength index , The core quality RQD and joint spacing index scores have been non-linear fitting research; the joint state index has been researched by the weighted average method; the groundwater correction coefficient has been introduced to increase the scope of application of the RMR method; the revised RMR method is in Shandong The engineering application of a gold mine showed that the revised RMR method can objectively evaluate the quality of rock mass; the rock mass quality of the mine’s granite and lamprophyre roadways are grade II and grade IV, respectively; the granite lithology roadway supports The support method is bolt + bolt net support, and the support method of lamprophyre lithology roadway is bolt + sprayed concrete + anchor net + anchor cable + steel arch.
- 1
Study on Prevention and Control Effect of Rockburst in Superhigh Water Backfilling MiningAbstract:
Safe, efficient and green mining of deep coal seams is a major problem to ensure the healthy development of national modern energy economy. In order to explore the prevention and control effect of superhigh water backfilling mining on rockburst, taking CG1302 working face of Shandong Yineng coal mine as the engineering background, it is explored by means of theoretical analysis, numerical simulation and field monitoring. It is concluded that mining depth, mechanical properties of coal and rock mass, overburden conditions, geological structure and roadway layout of working face are the main influencing factors to induce rockburst, and it is determined that Yineng coal mine has the conditions for rockburst. Based on the energy theory, the distribution law of coal deformation energy is analyzed, and the minimum kinetic energy of rockburst is calculated as Emin = 77kJ/m3; The energy accumulation in coal seams under different backfilling rates is simulated. Compared with caving mining, superhigh water backfilling mining can effectively reduce the energy accumulation degree of coal seams and prevent the occurrence of impact dynamic disasters. Field microseismic and coal pillar stress monitoring show that superhigh water backfilling mining can effectively reduce the working face pressure and achieve the effect of preventing rockburst.
- 1
Analysis of Dynamic and Static Characteristics of Pilot Valve Electromagnet Used in MineAbstract:
Taking the electromagnet on the electromagnetic pilot valve of the hydraulic support as the research object, analyzing the working characteristics of the pilot valve electromagnet, using the Maxwell finite element software to simulate the electromagnet, obtaining the static output characteristics of the electromagnet, and finding that the armature length is 28mm and the effect is best. Import the static characteristics simulation analysis results into AMESim, establish the electromagnet drive load dynamic system model, realize the electromagnetic-hydraulic-mechanical co-simulation analysis, and obtain the relationship between the electromagnet air gap, ampere-turns, inductance, and output force. It is found that the size of the initial air gap should be less than 0.8mm to improve the carrying capacity of the electromagnet.
- 1
Analysis of periodic pressure in super high mining face considering the heterogeneity of coal and rock materialsAbstract:
The influence of heterogeneity of coal and rock material on the law of super-large mining pressure phenomenon is considered, this paper takes a typical working face in Shendong mining area as an example, through theoretical analysis, numerical simulation and field measurement, periodic caving law of 8 m super-large mining height working face in Shendong mining area was studied. The rock microstructure density was proposed, the calculation formula for the periodic caving step distance was deduced, through user subroutine development, the numerical calculation model of heterogeneous coal and rock working face was established, the rationality of the theoretical model and numerical calculation results was verified by the field measurement results. The results show that considering heterogeneity of coal and rock material, the periodic caving step distance decreases linearly with the increase of the rock microstructure density. In the process of periodic weighting, the caving step distance of the working face with a height of 8 m is 15 m, which is consistent with the mine pressure monitoring results. This study has important reference significance for grasping the periodic caving pressure law of the 8-meter-high fully mechanized mining face in Shendong mining area and improving the safe mining of the fully mechanized mining face with super-large mining height.
- 1
Research on fracture process of similar materials coal sample under uniaxial compressionAbstract:
To analyze the fracture evolution process of roadway coal, taking the maintenance and reinforcement of geng-1 track roadway in No. 2 coal mine of Pingmei Co., Ltd. as the background, similar material coal samples with different mix proportions are prepared by using cement, gypsum and full particle size pulverized coal. The failure mode and crack evolution process of similar material coal samples are analyzed through uniaxial compression test and particle flow (PFC2D) numerical simulation. The results show that the stress-strain curve characteristics of coal samples of similar materials are similar to those of raw coal. The failure mode is mainly inclined section shear failure. The mix proportion samples with high pulverized coal content (cement: Gypsum: full particle size pulverized coal = 1:1:1.25) are closer to the failure mode of raw coal. Through PFC2D numerical simulation and indoor test, the stress-strain curve is in good agreement, According to the crack accumulation curve, the crack evolution process is divided into three stages: crack generation, crack propagation and crack penetration. The research results provide technical guidance for later similar material model test and roadway support.
- 1
Optimization of paste ratio parameters of total tailings based on limit mass fraction of deep cone bottom flowAbstract:
In order to overcome the defect that the recommended filling ratio of full tailings paste in existing studies did not consider the limit mass fraction of deep cone bottom flow, strength experiments were carried out based on comprehensive experimental design to optimize the filling ratio of full tailings paste slurry in a lead-zinc mine. In this paper, a comprehensive experimental design was adopted to study the influence of sand-cement ratio, mass fraction and curing age on the uniaxial compressive strength of the whole tailings paste, and a strength prediction model was established. According to the strength requirements of the backfill and the limit mass fraction of deep cone bottom flow, the ratio of the paste filling slurry was optimized. The results showed that the sand-cement ratio, mass fraction and curing age were important factors affecting paste strength. In the strength range analysis results of 4 d, 7 d and 28 d, the sand-cement ratio range was greater than the mass fraction range, and their P values were all less than 0.05 in variance analysis, indicating that the sand-cement ratio had a more significant effect on paste strength. The strength decreases exponentially with sand-cement ratio, increases quadratic with mass fraction, and increases logarithmic with curing age. The fitting accuracy of multivariate nonlinear quadratic polynomial regression model is high, and the correlation coefficients R2 are above 0.97. The ultimate mass fraction of paste slurry preparation under the condition that the strength requirements of backfill and the ultimate mass fraction of deep cone bottom flow are met, and the optimal range of paste slurry ratio is finally recommended.
- 1
Regional Stability Analysis and Risk Evaluation Research of Wide and Large BottomAbstract:
To conduct stability analysis and risk assessment of the wide and large bottom area of Huibaoling Iron Mine.Using on-site engineering geological survey, numerical simulation and other methods, the stability of stope structure and regional mining effects were studied.Research shows:The Q values of the upper and lower rock masses of the Huibaoling Iron Mine are 11.58 and 12.00, respectively, and the rock masses are medium-to-upper quality.The quality of the rock mass of the ore body is average, and the engineering span is only 7.32m, which is much smaller than the thickness of the local ore body. Therefore, the destruction of the wide and large pull-bottom structure mostly occurs in the ore houses with thick ore bodies.Using FLAC3d simulation to reveal the law of stress and strain changes in the mining area during different mining periods. Due to excavation, the upper bottom pull area has a large exposed area, and the suspended roof span is large, resulting in tensile stress on the roof.Combined with the layout of the mine room along the direction of the ore body, parallel to the joints of the ore body, it is easy to cause the destruction of the bottom pull area.Plastic failure mainly occurs on the roof of the mine building. The greater the thickness of the ore body, the more serious the plastic damage is. Most of the internal damage of a single mine is mainly caused. The penetration plastic damage effect is small. Has little effect.Therefore, rationally controlling the mining sequence of the same vein and optimizing the mining parameters of thick ore bodies are of great significance to the stability of the pull-bottom area.
- 1
Application of New High Strength Cementing Materials in Baoshan MineAbstract:
In order to make full use of the local backfill resources in Baoshan mine and meet the requirements of the curing time and backfill strength of the mine, the test on the cemented backfill ratio of the total tailings with new cementing materials as the cementing agent was carried out, and the test group with 42.5# ordinary portland cement as the cementing agent was compared to explore the advantages of the new cementing materials on the consolidation ability of the tailings, It provides a new idea for the selection of cementing materials for mine. The results show that: Baoshan mine belong to ultra-fine tailings, in which the content of tailings particles below 0.075mm accounts for 71%, and the median particle size d50=0.049mm. When the cement sand ratio and slurry concentration are fixed, the uniaxial compressive strength of the new cementing material backfill is significantly higher than that of the cement backfill When the curing age is 7 days, the uniaxial compressive strength of the new cementing material backfill is 3-5 times of that of the cementing backfill Therefore, using new cementing materials as gelling agent has a positive effect on improving the comprehensive utilization of tailings.
- 1
Numerical study on dynamic fracture behavior of defective rock mass under impact loadingAbstract:
To deeply study the influence of defect (empty hole) on crack propagation behavior under impact loading, based on the experimental study of dynamic fracture caustics of three-point bending beams with empty hole, the crack propagation behavior and stress intensity factor at crack initiation of three-point bending beams with empty holes under dynamic loading are studied by using ABAQUS numerical simulation method and equivalent region integral method, respectively. The results show that the crack propagation path obtained by the numerical simulation method is basically consistent with the experimental results. The stress intensity factor at the crack initiation is calculated by the equivalent region integral method with high accuracy, and the calculation error compared with the caustics experiment is 3.5% and 5.8%, respectively. The application of equivalent region integral method in ABAQUS has a good applicability to the study of fracture behavior, and further enriches the study of fracture behavior of defect (empty hole) rock mass under impact loading.
- 1
EFFECT OF UNLOADING IMPACT OF ORE PASS ON POROSITY DISTRIBUTION OF BOREHOLE STORAGEAbstract:
The blockage problem in ore drawing is closely related to the distribution characteristics of porosity in ore storage. To explore mine impact of ore block storage reservoir compaction range, the influence of the similar structures, and chute ore section of the model, the height and different discharge ore with iron ore mine impact of ore block storage reservoir compaction effect, reference porosity variation illustrates the current chute structure and ore mineral gradation, discharge chute ore impact of borehole storage compaction effect. The results show that :(1) the unloading impact at the upper part of the chute causes the storage bulk to rearrange and recombine, which changes the void ratio in a certain range below the storage surface; (2) Under the impact of bulk unloading, the porosity of the overall storage in the well varies from 200% to 250%, and with the increase of unloading height, the porosity gradually decreases, mainly concentrated in the range of 150 mm below the storage surface; (3) Under the impact of bulk ore, the variation range of storage porosity is much larger than that of granular rock with the same mass, and with the increase of unloading height, the porosity decreases, mainly concentrated in the range of 200 mm below the storage surface. Combined with the research results, the relevant measures are put forward to avoid the blocking of the pass caused by the unloading impact, which has certain guiding significance to the mine production practice.
- 1
Study on Farmers'' adaptive behavior mechanism of heavy metal polluted agricultural land in mining area based on Bayesian networkAbstract:
Mining area is a high incidence area of heavy metal pollution in agricultural land. Understanding the adaptive behavior selection tendency and its influence mechanism of farmers in mining area is very important for formulating scientific governance and control policies. Based on the questionnaire survey of farmers in typical heavy metal polluted mining areas in Daye City, These paper divide farmers'' adaptive behavior into risk response behavior and risk aversion behavior. Under the guidance of planned behavior theory, a Bayesian network model of farmers'' adaptive behavior in heavy metal polluted agricultural land in mining areas is established, Which includes four modules: Farmers'' characteristics, Pollution perception, Behavior willingness and Adaptive behavior, The results show that: ① Farmers'' pollution perception has little direct impact on their adaptive behavior, but farmers'' pollution perception can affect their adaptive behavior by affecting their behavior. The enhancement of farmers'' pollution perception can improve their behavior attitude, and their behavior attitude tend to shift to "positive". When farmers feel that the impact of pollution is very serious, their subjective norms will also increase, That use of agricultural land is more likely to be affected by others, The media or the government, But farmers'' perception of pollution has little impact on their perceived behavior control; ② The more sensitive variables to risk coping behavior are behavior attitude and land dependence. The enhancement of farmers'' behavior attitude and land dependence can significantly increase their risk coping behavior probability, The enhancement of farmers'' subjective norms and perceived behavior control can also increase their risk coping behavior probability, but the increase of farmers'' action damping will reduce their risk coping behavior probability; ③ The variables that are more sensitive to risk aversion behavior are household head quality and perceived behavior control. The improvement of household head quality will significantly increase the probability of risk aversion behavior. The enhancement of perceived behavior control can significantly reduce the probability of risk aversion, and the enhancement of farmers'' subjective norms and behavior attitudes can also reduce the probability of risk aversion behavior.
- 1
Safety Evaluation of Lithium Resources Supply in China under the Background of "Anti-globalization"Abstract:
Lithium is in recent years to be identified as a national emerging key mineral. Although China's lithium-ore resources are rich, my country's lithium resource supply capacity is poor, and China has become a largest national consumption in the world, and domestic lithium resources will maintain a rapid growth of 15% ~ 20%; especially Today, "Inverse Globalization" Today, in-depth study of China's resource supply safety and predicting future supply safety trends is necessary. This study selection 2009-2019 data, constructs four dimensions in the safe evaluation index system of China's lithium resource supply safety evaluation index system with resource mining safety, domestic supply and demand security, import market safety, and resource country, and use entropy rights TOPSIS model to China The safety trend evaluation of lithium resource supplies, based on the results of the evaluation results, using improved fractal gray models to predict supply safety trends in China's lithium resources in China 2020-2025. The results show that: (1) China's lithium resource supply is larger has a large impact on resource mining and import market. From a single indicator to see the degree of fluctuation of reverse globalization, "reverse globalization" risk has become an irreloaded safety factor; 2) Safety scores in 2009-2019 have been in a safe-basic security-dangerous fluctuations, from 2016, the safety score has decreased significantly, and the resource mining safety and the political security fluctuation of resources. (3) China's Lithium Resources Supply Safety Association achieves extremely dangerous state in 2022 and resource mining safety, domestic supply and demand security and resource policy have also declined, compared to the import market safety score in 2022-2025 Sprinkle trend. Key words：Safety evaluation; Inverse globalization; Entropy weight TOPSIS；; Grey prediction; Lithium resources
- 1
Construction of lignite macromolecular and its analysis of physisorption oxygen at low temperaturesAbstract:
The physisorption of oxygen by coal is one of the processes involved in the spontaneous combustion of coal. In this paper, a systematic study of the mechanism of oxygen physisorption by coal was carried out using Grand canonical Monte Carlo (GCMC) on the basis of the assumption of no chemisorption. Firstly, the surface molecular structure parameters of Chifeng lignite were determined and a coal surface macromolecular model (CMM) was constructed; secondly, the CMM was optimised and periodic boundary conditions were added. Then, the macroscopic adsorption behaviour of the coal molecule periodic boundary condition unit (CBu) on oxygen was simulated. Finally, the radial distribution function (RDF) of oxygen molecules and each functional group in coal was analysed. The results show that ambient temperature plays a negative role in the amount of oxygen adsorbed on coal molecules and the generation of heat of adsorption; coal molecules physically adsorb oxygen mainly through van der Waals forces and electrostatic interactions. The analytical results of the simulated adsorption are important for improving the efficiency of fire prevention in underground coal seams and improving the safety level of coal mines.
- 1
Research on the application of high-efficiency large-scale mining technology for slow and thin veinsAbstract:
Abstract：Application of mining method for Jintang No. 1 vein type orebody in Huangjindong Gold Mine，Restricting factors and difficulties in achieving high-efficiency and large-scale mining。The technical conditions for the mining of the ore body are gentle、thin、 brittle 、roof and changeable trend tendency，The mining technology of this type of ore body is difficult，Has always been a technical problem that plagued mines，Thus restricting the development of the mine’s technology and economy。In this study, a comprehensive and detailed investigation and analysis of the mining technical conditions of the ore body；Experimental calculations have determined the characteristics of the physical and mechanical technical parameters of the ore body and the roof surrounding rock；The method of simulation calculation is used to obtain the structural parameters of safe mining under the condition of support；Using multiple types of empirical parameters to compare the median value to determine the large-scale rock drilling and blasting parameters of the stope；Developed large-scale blasting technology for multi-slot combined use；Good results have been achieved through on-site industrial tests。
- 1
Optimization of Stope Structure Parameters Based on Response Surface MethodAbstract:
In view of the optimal selection of structural parameters of underground mines, the response surface method is used to design the test plan, and the FLAC3D numerical software is used to carry out the test simulation. Through the analysis and comparison of the numerical simulation measured value and the response surface predicted value, it is verified that the difference between the response surface predicted value and the numerical simulation measured value is small; and the relationship between each influencing factor and the stability of the stope is clarified. The order of the degree of influence of field stability is: length of mine room>width of inter-pillar>thickness of top pillar. Based on this, an optimization model between stope stability and various stope structure parameters was established, and the stope structure parameters were optimized for a tungsten-molybdenum mine utilization model. The results show that the length of the mine room is 48.25m, the width of the pillars is 10m, and the thickness of the top pillar is 4m are the optimal stope structure parameters of the mine. Numerical simulation and technical and economic analysis and comparison of the above parameters show that the optimized stope stability is good , The cutting comparison is obviously lower before optimization, which proves that the response surface method is applied to the optimization of stope structure parameters has good applicability.
- 1
STUDY ON ADSORPTION AND DESORPTION BEHAVIOR OF METAL IONS ON CARBON SURFACE BASED ON QCM-DAbstract:
The mechanisms of metal ions at the solid-liquid interface of coal is of great significance to clean processing and utilization of coal, efficient recycling of water and mineral resources and "carbon emission reduction". The adsorption and desorption behavior of K+, Mg2+, Al3+ and Fe3+ on carbon surface was studied by dissipative quartz microcrystalline balance (QCM-D). The results show that the increase of concentration and valence state is conducive to improve the adsorption of metal ions. The interaction between four metal ions and carbon surface is ranked as: Fe3+ > Al3+ > Mg2+ > K+; K+ and Mg2+ show single-stage adsorption and reach adsorption equilibrium within 2 min. With the increase of adsorption mass, the compactness of the adsorption layer has no obvious change, and can be completely desorbed after washing with water; The adsorption of AlCl3 solution is completely reversible only under the condition of high concentration of 100 mmol/L. In the case of low concentration of 10 mmol/L and 50 mmol/L, AlCl3 shows two-stage adsorption characteristics. Although the amount of adsorbent in the first stage is less, it is more compact than that in the second stage. After desorption, there is still a small amount of compact adsorbent residue; FeCl3 solution is quite different from other solutions. Within the concentration range of 10-100 mmol/L studied, the adsorption is not completely reversible. The lower the concentration, the more obvious the characteristics of multi-stage adsorption and irreversible adsorption, and the higher the residue mass after desorption. In the desorption process, the adsorbents with loose structure are preferentially desorbed from the surface, and the adsorbents with compact structure remain on the carbon surface. The irreversible adsorption behavior of FeCl3 and AlCl3 is related to their hydrolysis reaction. The lower the concentration, the easier it is to form non-desorbable Fe (OH)3 and Al(OH)3.
- 1
Research Progress of Mine Ecological RestorationAbstract:
This article introduces the current domestic and foreign research status of mine ecological restoration from four aspects: basic theoretical research, slope protection technology development, restoration effect evaluation, and ecological benefits. Based on the existing foundation, conclusions are drawn and prospects are put forward: ( 1) Mine ecological restoration should focus on national development needs, establish a more scientific and reasonable ecological restoration system and long-term management and monitoring mechanism, so as to coordinate the development of mineral resources development and ecological governance; (2) Strengthen multi-disciplinary and multi-field collaborative innovation Cooperate to improve the degree of compatibility between the theoretical research and engineering practice of mine ecological restoration; (3) Determine the type of mine restoration based on the actual situation of the mine and original data, and formulate scientific and reasonable restoration plans based on local conditions; (4) Based on existing research Establish a mine ecological restoration benefit evaluation system that meets the needs; (5) Partial targeted research needs to be strengthened in mine ecological restoration, and slope restoration will be the focus and difficulty of its research; (6) Strengthen the theory of mine ecological restoration under special habitat conditions And technical research, compile relevant technical standards.
- 1
Research on Gas-solid Two-phase Flow Field Based on CFD-DEM Coupling Simulation in Grab UnloadingAbstract:
In order to solve the problem of dust diffusion caused by the free fall of bulk materials in the process of grab unloading, the gas-solid two-phase flow field is studied in order to reflect the movement of dust through the velocity and trajectory of the air flow field. in order to judge the amount of dust escape. By using the numerical simulation method based on CFD-DEM coupling, the velocity distribution of particle flow field, the trajectory and velocity distribution of air flow field, the interaction and variation law of gas-solid two-phase flow field at different times are obtained, and the escape flow area S, mass flow Q, escape velocity V and flow angle θ are analyzed. Furthermore, the suspension velocity of dust particles under different particle size dp and air flow angle θ is deduced. Combined with the above data and derivation formula, the escape law of grab discharge dust under different working conditions can be analyzed, which can provide guidance for taking targeted dust reduction methods and measures and efficiently solving the problem of dust diffusion.
- 1
Research on "Spraying-Anchoring-Grouting" Reinforcement Technology for Deep Large Section Soft Rock ChamberAbstract:
With the continuous increase of the section of coal mine chambers, the deep large-section soft rock chamber is difficult to support and maintain due to the broken surrounding rock, large section, and high stress of the roadway. Taking the maintenance of a substation in a suburban mine as the research object, using theoretical analysis, numerical simulation, and on-site construction as research methods, the failure characteristics of deep large-section soft rock chambers are analyzed, and the "spray-anchor-injection" reinforcement technology is analyzed. Mechanism, and proposed the "spray-anchor-injection" reinforcement technology, that is, the "three-injection + anchoring + grouting" support program. Mine pressure observations show that after the maintenance of the large-section soft rock chamber, the maximum deformation of the two sides is about 108.9 mm, the maximum deformation of the roof and floor is about 109.5 mm, and the deformation of the soft rock chamber is relatively small. Field practice shows reinforcement technologies and solutions can effectively maintain the stability of the deep soft rock cavern with heavy section and bearing structure, to solve the similar geological conditions of deep soft rock cavern with heavy section and roadway support, provides the reference to solve the problem of deep large section roadway supporting and soft rock cavern stability control problem has important practical significance.
- 1
Study on the effect of acidification on nano pores of different rank coalAbstract:
In order to find out the influence of exposure area and adsorption time on gas adsorption, taking briquettes with different exposure area as the research object, the isothermal adsorption tests of methane and carbon dioxide were carried out for 30 min, 60 min, 90 min and 12 h by using isothermal adsorption tester. The results show that: (1) in the process of gas adsorption, with the increase of exposure area, the adsorption capacity per unit pressure increases. The larger the exposure area is, the greater the adsorption capacity is. (2) The coal sample has the largest adsorption capacity and the fastest adsorption rate in the first 30 minutes, and the adsorption rate slows down obviously in 30-90 minutes; the adsorption rate of carbon dioxide is higher than that of methane. (3) The adsorption capacity per unit pressure under low pressure is greater than that under high pressure. The research results can provide a certain theoretical basis for gas disaster prevention and control.
- 1
Experimental Study on Preconcentration of Semi-autogenous Mill and High Pressure Roller Mill for Anshan Type Low Grade Iron OreAbstract:
Anshan type low grade iron ore was treated by semi-autogenous grinding and high-pressure roller grinding. The product characteristics and pre-concentration of weak separation-high intensity magnetic process were studied, and the pre-concentration effect and its influence on separation were compared.SSIn the pre-selection test, the magnetic induction intensity of the drum surface of the magnetic separator was 200mT, the magnetic field intensity of the magnetic separation was 1000mT, the vertical ring speed was 3.0r /min, the pulsating stroke was 200-300 times /min, and the pulsating stroke was 10 mm.SSThe experimental results of wet preconcentration of semi-autogenous grinding products and high-pressure roller grinding products were compared, and the characteristics of particle size, grade, yield and metal distribution of feed ore and coarse concentrate were compared with those of wet preconcentration of semi-autogenous grinding products and high-pressure roller grinding products.SSThe pre-concentration test results show that the TFE grade of the selected raw ore is 24.99%. After grinding by HPGR and semi-autogenous grinding, the TFE grade of the pre-concentration products is about 30.5%. However, compared with the semi-autogenous grinding products, the pre-concentration concentration of HPGR products is 1.08% higher, and the recovery rate is 1.24% higher.SSThe screening accumulation curve shows that the pre-selected coarse concentrate of HPGR products is coarser than that of semi-autogenous grinding products. Most of the iron in HPGR products is concentrated in the coarse grain size, and the HPGR products can obtain better disintegration effect under the condition of coarser grain size.SSThe grindability test results show that HPGR products are easier to grind than semi-autogenous grinding products. SS
- 1
Experimental study on point load strength of red sandstone based on size effectAbstract:
Taking the red sandstone of Nanhua quarry in Wuding County, Yunnan Province as the research object, the core samples with different sizes are prepared. The point load axial test and radial test are carried out by using the self-developed portable point load instrument. Combined with the uniaxial compression test, the influence of size effect on the point load strength of regular core samples and the relationship between point load strength and uniaxial compressive strength are analyzed. The test results show that the point load strength has obvious size effect, and the influence of specimen diameter and thickness on the point load strength is different under different loading modes; The relationship between shape coefficient and point load strength is analyzed, and the recommended value range of shape coefficient under different loading modes is put forward; The empirical conversion formulas of point load strength and uniaxial compressive strength of red sandstone in this area are obtained, in order to provide reference for engineering application in this area.
- 1
Research on Reinforcement of Weak Surrounding Rock and Field ApplicationAbstract:
Building tunnels can solve the problem of inconvenience in mountainous areas and promote the rapid development of the local economy. Tunnel construction has great significance to society. However, the surrounding rock is not a homogeneous body, and many tunnels often encounter weak surrounding rock during construction, and must be reinforced to ensure construction safety. Taking Fujian Liucheng Tunnel as an engineering case, FLAC3D is used to construct a calculation model; the tunnel convergent deformation, the distribution of plastic zone and the force characteristics of the supporting structure under different supporting parameters are systematically studied. Through the analysis of the effects of each plan, combined with the mechanism of controlling the deformation of the surrounding rock of the supporting structure, the simulation plan was combined and optimized based on the principle of construction safety, economical and reasonable. Finally, the soft surrounding rock tunnel was strengthened by the combined support plan. Practice shows that the optimization plan is effective, the deformation of weak surrounding rock is reduced, and the on-site convergence measurement and borehole imaging results are consistent with the numerical simulation, which can provide a reference for tunnel construction and coal mine roadway support under the same type of geological conditions.
- 1
STUDY ON THE IMPACT OF HUMAN ACTIVITIES ON ECOSYSTEM SERVICES IN THE WESTERN ECOLOGICALLY FRAGILE REGION-- TAKE ORDOS CITY AS AN EXAMPLEAbstract:
Human activities disturb the structure and function of regional ecosystem, and then affect the quality and value of ecosystem services. Quantitative evaluation of the impact of human activities on ecosystem services is the basis of value realization of ecological products and natural resource assets accounting.This study takes Ordos City as an example, taking Dongsheng mining area, Zhungeer mining area and urban development area as the study area, the ecosystem is affected by human activities and natural factors, and the nature reserve area, which is almost not affected by human activities, as the control area, selects three main ecosystem services, namely, wind-break and sand-fixation, soil conservation and carbon sequestration. Based on the RULSE and RWEQ models, shadow project methods and market methods, a remote sensing assessment model for the quality and value of ecosystem services was established to uses comparative analysis method to analyze the impact of human activities such as underground mining, strip mining and urban development on ecosystem services during 2005-2020. The results show that : Urban construction has the greatest negative impact on wind-break and sand-fixation services and carbon sequestration services, and strip mining has the greatest negative impact on soil conservation services. After eliminating the influence of natural factors, the impact rate of human activities on the ecosystem service value of Dongsheng mining area, Zhungeer mining area and urban development area is -3.51%, -3.61%, -3.80%. The influence degree of human activities in ecologically fragile mining areas of western China from large to small is as follows: Urban Development > strip mining > underground mining.
- 1
Dynamic compression characteristics of coal under different confining pressures based on triaxial SHPBAbstract:
The frequent and intensity of dynamic disasters in coal mines such as coal bumps and the outbursts of coal and gas is still one of the main problems affecting coal mine safety. To study the role of the stress around the coal on the evolution process of dynamic disasters, this paper adopts the active confining pressure triaxial split Hopkinson pressure bar (SHPB) experimental system to carry out triaxial dynamic compression experiments on the coal under different confining pressure with the same loading rate. In the experiment, the impact loading air pressure was 16 psi to achieve the same loading rate, the axial pressure parameter was fixed at 6 MPa. Using the controlled variable method, the confining pressure parameter was selected from 2 MPa to 10 MPa with a gradient of 2 MPa. Through the waveform signals collected in the experiment, the stress-strain curve pattern of the coal sample in the triaxial dynamic compression process, the relationship between the peak strength and the confining pressure, and the relationship between the failure strain and time are analyzed. The experimental results show that the peak strength of the coal increases linearly with the increase of the confining pressure, and its linear fit is at 95.88%, The macroscopic crushing state transitions steadily from completely crushed to uncrushed, indicating that the larger the horizontal principal stress of the coal seam, the greater the energy required for the complete crushing of the coal, the more severe the damage of the dynamic disaster; The results of the triaxial dynamic compression of the coal confirm that the confining pressure does not change the time required for the coal to break from loading to damage, but only changes its dynamic strength and failure strain, which indicates that the magnitude of the stress field of the coal does not change the catastrophic time of the dynamic disaster, but only changes the strength and severity of the disaster damage. This study is helpful to improve the triaxial coal dynamics and provide a theoretical basis for studying the effect of the stress field environment on dynamic disasters.
- 1
Effect of balling system on granularity characteristics of granite porphyryAbstract:
In this paper, molybdenite carrier ore granite porphyry is taken as the research object to explore the influence of three pelleting systems on the grinding-size characteristics of granite porphyry. The results show that when the grinding grain size is -2mm, the grinding fineness can be improved by 9.06% under the precise ball packing system compared with the larger ball loading system, and the overcrushing grain size can be reduced by 11.57% compared with the smaller ball loading system. When the grinding grain size is -6.7mm, the yield of -75μm grinding product under the precise ball loading system is 23.61% higher than that under the partial ball loading system, and 20.47% higher than that under the partial ball loading system. The particle size characteristics of grinding products with precise pelleting system are more uniform, and the recovery rate of flotation concentrate is obviously higher than the other two. In the closed circuit flotation experiment, the crude concentrate with molybdenum grade of 15.40% and recovery of 95.55% can be obtained, and the separation effect of sulfur and molybdenum is better.
- 1
OPTIMIZATION ON MINING TECHNOLOGY TO IMPROVE MINING EFFICIENCY OF THICK ORE BODIESAbstract:
To further improve the mining efficiency of the iron ore bodies of thick ore bodies, the mining technology of the 2# thick ore body of a certain iron mine located in the eastern Liaoning was optimized using the non-pillar sublevel caving method. The layout of the single transportation roadway in the footwall country rock was arranged to one transportation lanes each in the country rock of footwall and of hanging wall, the cut-out drift was changed from along the hanging wall boundary of the ore body to the center of the ore body thickness, and the cut-off stopping is changed to non-raise cutting. Compared with the mining process before optimization, one transportation roadway was added, the length of the mining drift is reduced to 50% of the original length, and the ore transportation distance is reduced by 35.71%. The ore production capacity of the mining drift has been increased from 1066t/d before optimization to 2843t/d. The ventilation effect of the working face of the mining drift has been greatly improved, and the production capacity and mining efficiency of the mine have been significantly increased.
- 1
Experiment Design and Analysis on the Permeability Characteristic of Cemented Unclassified Tailings BackfillAbstract:
To obtain the permeability characteristic of cemented unclassified tailings backfill (CUTB), the permeability experiment and the effect of cement to tailings ratio, curing age and confining pressure on the permeability of CUTB sample is designed and investigated. The permeability coefficient of CUTB under different conditions is tested by a triaxial shear permeability apparatus, and the permeability mechanism is revealed based on microstructural testing results. The results show that the longer curing age is and the more cement content is, the smaller permeability coefficient is. The permeability coefficient decreases instantly and then tends to be stable as the confining pressure increases, and the change law conforms to the power function model. The increasing of cement content and curing age result in the decrease in porosity and the change in pore size of CUTB, which leads to the decreasing in tortuosity and permeability coefficient. The results will be beneficial for mining engineering professionals and students to further understanding the permeability feature of CUTB. Furthermore, it will provide reference for design and optimization of underground backfill mining.
- 1
Study on the damage and failure of different size of cemented gangue backfill body under uniaxial compressionAbstract:
In order to study the damage and failure of cemented gangue backfill body with different sizes in the process of compression, Cube Specimens with sizes of 50mm, 70mm, 100mm and 150mm were prepared for uniaxial compression test, the changes of acoustic emission during loading were monitored, and the micro morphology of the backfill body was observed by scanning electron microscope, The damage evolution law of cemented gangue backfill body is analyzed. The results show that the compressive strength of the backfill body increases first and then decreases with the increase of the size. The compressive strength of the specimen is the largest when the size is 100mm; The failure mode of the specimen gradually changes from splitting failure to X-shaped conjugate shear failure with the increase of size. The change of acoustic emission energy in the process of uniaxial compression of backfill body can be divided into four stages, which has a good corresponding relationship with the stress-strain curve. The acoustic emission energy of backfill body will surge at the peak strain, which can be used as a precursor of backfill body failure. The energy of specimens with different sizes changes greatly in the post peak failure stage.
- 1
Mechanical properties and energy consumption characteristics of alkali rice straw based cemented tailings backfill under impact loadAbstract:
In order to understand the intensity of dynamic load, stress-strain, energy evolution and failure morphology characteristic rules of the alkali rice straw based cemented tailings backfill under medium strain rate, the uniaxial single impact load test of the tailings cemented backfill with different contents of alkalized rice straw (alkalized by NaOH solution) was carried out by using the split Hopkinson pressure bar (SHPB) system. The test results showed that the dynamic compressive strength of the backfill was positively correlated with average strain rate and effectively improved due to the addition of alkalized rice straw, and with alkalized rice straw content increased, the dynamic compressive strength of the backfill first increased and then decreased, and the optimal addition amount was 0.3%, the biggest increase was 26.81%; Under single impact load, the backfill mixed with alkalized rice straw should be changed more than the backfill without alkalized rice straw, but the damage degree was smaller; Under the same strain rate, the energy absorption per unit volume and the crushing energy consumption per unit mass of the backfill showed a similar exponential growth law with the increase of the average strain rate, the backfill doped with alkalized rice straw had higher energy level, higher energy absorption performance and more energy consumption during crushing; Under single impact load, the failure form of the backfill was mainly axial main crack tensile failure and crushing failure on the macro level, and when the average strain rate exceeded the critical strain rate, the failure form of the backfill was mostly crushing failure; The alkalized rice straw could form a bridging role with the inner matrix of the backfill, which could slow down the crack propagation and energy release, made the backfill doped with alkalized rice straw had a higher critical strain rate, significantly improved the stability and integrity of the backfill, and is conducive to improving the safety of the underground operation environment.
- 1
Update Method of Dump Model and warning line of dump for Open Pit TruckAbstract:
To solve the problem of the safety of the abandoned mine dump caused by the frequent change of the dump edge line, update method of dump model and warning line of dump for open pit truck based on point cloud data are presented. Firstly, the airborne radar is used to collect the point cloud data of the dump of open-pit mine, and the key region feature is retained to simplify the point cloud data of the dump. In addition, the model area which needs to be updated is calculated by judging the elevation change of point cloud data, and the model change area is updated by software. Then, the important edge warning line of the uninhabited mine car is calculated by dividing the regional differential latitude of the point cloud data and fitting the point cloud data. Finally, the data of open dump in Luoyang Molybdenum mine are modeled and warning lines of dump are updated. The results show that the method can effectively avoid the safety accident of unmanned vehicle dumping.
- 1
Numerical Simulation Research on Modified Pressure-regulated Transportation of Full Tailings Filler SlurryAbstract:
Using computational fluid dynamics CFD software, a large-scale three-dimensional numerical calculation model was established based on the pipeline layout of the Sanshandao Gold Mine. Set the ratio of lime to sand at 1:5, the concentration of 68%, 72%, and whether to add low-density agent, etc., and carry out numerical simulation. According to the results of numerical simulation, the higher the concentration of filler slurry, the higher the pipeline pressure. The maximum pipeline pressure appears in the middle section of -960m, and the minimum pipeline pressure appears in the middle section of -330m. The numerical simulation law is consistent with the actual scene. Compared with the control group without the low-density agent, when the low-density agent is added, the lime-sand ratio is 1:5, and the pressure drop of the pipeline with the mass concentration of 68% and 72% is 22.88% and 23.40%, respectively. It shows that adding a low-density agent to the filler slurry can reduce the pipeline pressure, and the reduction of the pipeline pressure meets the expected target.
- 1
Development and application of similarity test bench of temperature field in gob areaAbstract:
At present, it is difficult to simulate the temperature field in the goaf dynamically by using similarity test benches. In order to study the distribution law of temperature field in goaf areas, in a similar material simulation experiment principle as the basis, design and build the similarity test bench. According to the "O" ring theory, the test bench is partitioned to reflects the heterogeneity of the goaf porosity. The test bench is filled with the developed self-heating material. Through the simulation experiment of a mine in Shanxi Province, the dynamic experiment was carried out on the temperature rise law of goaf. The results show that the high temperature area in the goaf is close to the return air side and will move forward with the advance of the working face.
- 1
EFFECT OF SEWAGE SLUDGE COMPOST ADDITION ON ACTIVITY OF HEAVY METAL AND GROWTH OF ALFLFA IN LEAD/ZINC TAILINGSAbstract:
In order to reduce the heavy metal pollution of lead/zinc tailings and solve the problem of plant growth difficulties in lead/zinc tailings. The pot experiment was carried out, 0%(CK), 5%, 10%, 20%, 30%, 40%, 50% and 100% sewage sludge compost methods were applied on the surface 4 cm of tailings to remediate lead/zinc tailings. The results showed that when the dose of sewage sludge compost reached 30%~40%, it could effectively promote the growth of alfalfa, significantly increase the content of available nutrients in tailings, and effectively reduce the concentration of heavy metals. It can provide a theoretical basis for the remediation of lead/zinc tailings in the future.
- 1
RESEARCH ON SAFETY EVALUATION MODEL OF ROCK COLLAPSE BASED ON MULTIPLE TIME DOMAIN INDEXESAbstract:
The occurrence of dangerous rock collapse often brings great economic losses, casualties and adverse social impacts. However, traditional methods such as limit equilibrium are difficult to form safety evaluation techniques that can be applied to engineering sites. According to the characteristic changes of the collapse process of the dangerous rock mass, it is a new technical method to use multiple time-domain indicators to evaluate the safety of the dangerous rock mass. First, conduct indoor test research on the whole process of the collapse of dangerous rock mass, use laser doppler vibrometer to obtain the time domain information of rock mass vibration, and then introduce multiple time domain indicators such as vibration variance, trajectory history, and skewness to construct a safety evaluation model. Experimental research shows that the safety evaluation model with multiple time domain indicators can accurately determine the stable state of rock masses, and can provide early warning of rock mass collapse about 60 seconds in advance. In addition, comparing the changes of multiple time domain indicators and the whole process of the collapse of dangerous rock masses, it is found that the synchronization of the changes of multiple time domain indicators can respond to different stages, which provides a sign for identifying random vibration information and provides guidance for early manual intervention. It can reduce the loss caused by the collapse of dangerous rock mass. The safety evaluation model of the dangerous rock mass proposed in this study also provides a new idea for the study of the mechanism of the collapse process of the dangerous rock mass.
- 1
Research on the Influence of Lianhuashan Landslide and Collapse in Shirenzhang mineAbstract:
Shirenzhang mine has a long history of mining. After 100 years of long-term mining, the 1100m length and 600m vertical underground mining area has been formed in Lianhua Mountain, including a large number of goafs. In order to calculate and analyze the stability of Lianhua Mountain and the influence range of landslide caused by the collapse of goaf, UAV surface measurement, geophysical detection and three-dimensional laser scanning were used to establish the overall surface model of Lianhua Mountain and accurately internal goaf, and the calculation model was successfully constructed. Through the calculation of the displacement and safety factor of the mountain and the analysis of the influence range of the rolling stone, the influence range on the foot of the mountain is obtained, because of the collapse of the goaf at the top of the mountain, which provides a reliable basis for the layout of the production and living industrial sites at the foot of the mountain.
- 1
Application of metal magnetic liner in first stage grate ball millAbstract:
In view of the less application of metal magnetic liner in medium and large grate ball mills in nonferrous metal mines and gold mines, on the basis of summarizing the difficulties of field application, taking Nanjing Qixiashan lead zinc mine as an example, the solutions of applying magnetic liner in one-stage grate ball mill are put forward, including improving formula and structure, optimizing smelting process, changing the liner design of manhole door, using magnetic materials with high performance and improving the use habits of users, the production has achieved the following results: the efficiency of ball mill has been increased from 1300 t/d to 1319 t/d, and the fineness of overflow is 75%~80% -0.074mm, which has been increased by 2-3 percentage points; The service life of liner is 2-3 times longer than that of manganese steel liner, and the replacement time of liner is shortened from 6 days per year to 1 day per year; the working current of the ball mill is reduced from 34A to 30A, and the noise around the ball mill is reduced from 105dB to 95dB; The purpose of improving the service life of the liner, reducing the on-site grinding cost and increasing efficiency for the enterprise is achieved.
- 1
Numerical simulation of solid - liquid mixing in a strong mixerAbstract:
The solid-liquid mixing process was numerically simulated by using the Euler multiphase flow model and k-ε turbulence model for a three-layer dislocated 45° tooth impeller agitator in the laboratory using the computational fluid dynamics (CFD) software Fluent. The characteristics of solid-liquid mixing flow field and the distribution of solid particles in the process of mixing slurry with powerful agitator were analyzed, and the mixing performance was studied and discussed. The results show that during the mixing process of the powerful mixer, the particles form a relatively stable circulation in the flow field, the volume fraction of each part of the particles reaches a balance, and three stable circulation flows are formed. When the rotating speed is 20 rad/s and 40rad/s, the balance time of the particle volume fraction in the mixer is 20s, but there is a certain concentration difference. When the rotational speed is 60, 80 and 100rad/s, the equilibrium time is 8s, 6s and 3s, respectively. At this time, the volume fraction of particles in the flow field is equal, and the concentration difference is eliminated. The influence of mineral particle size on stirring power under different rotating speeds was studied through simulation calculation and formula calculation of stirring torque value. It was believed that the stirring power increased with the increase of mineral particle size and rotating speed. And the influence of rotational speed on stirring power is more obvious.
- 1
Mine Dynamic Monitoring Method Based on UAV ImageAbstract:
In recent years, with the continuous increase of exploitation and utilization of mineral resources, safe, reasonable and compliant production of mining enterprises has become particularly important. However, in the process of mining, many illegal behaviors such as cross-border mining, overspeed mining and unauthorized change of mining species occur in some mines from time to time. In order to promote the high-efficiency production of Chinese mining enterprises, it is very urgent to carry out dynamic monitoring of mining. Therefore, this paper takes UAV image data as the main data source. Firstly, key algorithms for dynamic monitoring of mining, such as mine crossing boundary monitoring, mine mining amount monitoring, mine remaining reserves monitoring, and mine multi-phase comparison change monitoring, are designed for relevant illegal mining behaviors. Then, a set of mine dynamic monitoring system is designed and developed on the basis of SuperMap Objects secondary development platform, in order to provide visual tools for mine dynamic monitoring and technical support for the determination of illegal mining in mines. Compared with the traditional mine mining monitoring, the mine dynamic monitoring method constructed in this paper greatly reduces the workload of relevant technical personnel, saves a lot of time cost, and has a better application value and promotion prospect.
- 1
Research on Safety Management System of Tailings Pond Based on UAV Intelligent CruiseAbstract:
In response to the demand for timeliness in the safe production management of tailings ponds, a quick inspection of the hidden safety hazards in the tailings pond area is proposed, and a tailings pond safety management system based on drone intelligent cruise is proposed. Based on the UAV intelligent safety cruise platform, the system quickly generates a virtual model of the inclined three-dimensional tailings pond, and uses WebGIS technology to visualize the data, realizes the dynamic management of the tailings pond safety risk, and builds a tailings pond spatial information database platform. The results show that the tailings pond safety management system can quickly perform vector analysis on the image, evaluate the safety status of the reservoir area, give out the hidden safety hazards in the reservoir area, analyze the influencing factors that cause the hidden safety hazards, and issue reasonable rectification instructions to assist the mine. Safety production dynamic management.
- 1
Anisotropy Analysis of Compressive Strength of Fractured Rock Mass Based on Statistical Mechanics of Rock MassAbstract:
The theory of Statistical Mechanics of Rock Mass takes fractured rock mass as the equivalent continuum and puts forward a strength criterion which can reflect the anisotropy of rock mass.In this paper, the effectiveness of the strength criterion is verified by laboratory test results and Hoek-Brown criterion.In order to investigate the anisotropic characteristics of compressive strength of fractured rock mass with a single joint, FLAC3D software with statistical fracture constitutive model after secondary development is used to carry out uniaxial and conventional triaxial compression tests on rock mass with different jonit dip angles under different confining pressures. The simulation results show that with the increase of joint dip angle, the uniaxial compressive strength of the fractured rock mass decreases first and then increases, and the minimum value appears when the joint dip angle is between 45° and 60°, and the variation curve of the strength with dip angles is shaped like a spoon with asymmetrical sides. When the joint dip angle is small or the loading direction is close to parallel to the joint ,stress concentration occurs at the upper and lower ends of the column, and the strength of the rock mass is relatively high, indicating that the strength of the rock mass is mainly controlled by the intact rock and the influence of the joint is relatively weak, especially when joint dip angle <23° (friction angle of joint), the jonit is "locked up" and the rock mass strength is equivalent to the intact rock;In the presence of confining pressure, the relationship between compressive strength and confining pressure of fractured rock mass is linear,and the fluctuation range of compressive strength curve becomes smaller, and the anisotropy of rock mass strength decreases with the increase of confining pressure. The mechanical effect of the joint in the rock mass is gradually reduced, and the control effect of the joint is changed.The strength changes from structural control to stress control.
- 1
Research and application of multi-objective optimization decision model for mine microseismic monitoring networkAbstract:
The optimization of microseismic monitoring network is an important step to ensure the performance of microseismic monitoring system.In view of the problems existing in the evaluation and optimization of microseismic monitoring network in the past, this paper introduces the two indexes of microseismic monitoring range and sensor installation parameters into the index system of microseismic monitoring network layout, and uses the multivariate statistical method PCA analysis method.Using MIDAS, FLAC3D and DIPS software, the multi-objective optimization decision model of microseismic network was built. Taking a gold mine as an engineering background, the application effect of the model was verified.The results show that;The model proposed in this paper can better serve the needs of mine microseismic monitoring network layout and optimization, and the model evaluation index system is complete, the evaluation process is objective, and can meet the actual production needs.
- 1
Research on microwave assisted modified lignite straw biochar and its adsorption of CrAbstract:
The pollution of heavy metal Cr (VI) is a major problem to be solved at present. Biochar adsorption is one of the most economical methods. In order to solve the problem of low adsorption rate, biochar was prepared from lignite and rice straw. Response surface methodology was used to investigate the modification of biochar with NH4Cl, FeCl3 and CaCl2 under microwave-assisted conditions. Furthermore, the biochar was characterized by FTIR, XRD, SEM, etc. Finally, the adsorption of heavy metal Cr (VI) by modified biochar was studied. The results showed that the optimal conditions were as follows: FeCl3 modified, at 60 ℃, pH 7 for 6h, and the adsorption rate was 95.8%. After FeCl3 modification, the specific surface area of Langmuir increased from 52.24 m2/g to 127.54 m2/g, and a large number of micropores appeared on the surface, which was conducive to the adsorption of heavy metals.
- 1
IMPROVED FCOS METHOD FOR PEDESTRIAN DETECTION IN UNDERGROUND COAL MINEAbstract:
An improved FCOS (FCOS: A Simple and Strong Anchor-free Object Detector) coal mine underground pedestrian detection algorithm is proposed for the problems of insufficient accuracy, high real-time, and complex environmental conditions for pedestrian detection in underground coal mine work. The model uses a lightweight convolutional neural network ShuffleNetV2 to replace the backbone network ResNet-50 in the FCOS detection algorithm, improves the feature pyramid structure in the original network into a top-down and bottom-up path enhancement network, and uses a lightweight detection head consisting of two sets of depth-separable convolutions to replace the detection head of the original FCOS network. During the experimental training, the generalization ability and robustness of the model are enhanced by scaling and color data enhancement of the downhole pedestrian detection data. The experimental results show that the improved FCOS can better achieve the balance between accuracy and speed, and the algorithm achieves an mean average precision of 51.9% with essentially no loss of accuracy, and the detection speed can reach 100 frames/s.
- 1
Study on layout optimization of high directional borehole in goaf of close coal seam groupAbstract:
In order to solve the problem that the gas in the left coal in the goaf and the adjacent coal seam in guizhou mining area escapes to the working face under the influence of mining disturbance, taking the 10605 working face of a mine in Guizhou province as the engineering background, this paper studies the layout optimization of high position drilling combined with theoretical analysis and numerical simulation. The results show that the height of caving zone is 11m, the range of fracture zone is 11~38.4m, and the adjacent coal seam is in the range of roof fracture zone, which will be affected by mining disturbance; The stress concentration factor of the crack zone in the roof ranges from 0 to 0.6, among them, the pressure relief zone with stress concentration factor less than 0.4 has better development of gas conduction cracks, which is 15~25m away from the roof and 10-20m away from the return air tunnel. Engineering practice shows that the optimized drainage measures effectively control the gas overlimit problem, the average gas extraction concentration of the 8 boreholes is about 42%, and the pure gas extraction quantity of the main borehole is 12.32 ~ 15.5m3 /min; The average gas concentration in the lower hole is larger than that in the upper hole, and the closer the hole is to the stope, the higher the average gas concentration is, which is corresponding to the development of "O-ring" gas fracture; After a certain time of extraction, the gas concentration in the upper corner of the goaf decreased from 0.68% to 0.32%, which was in line with the safety production standard.
- 1
Effect mechanism of activator-modified cement-slag filling on macro-mechanical propertiesAbstract:
To address the problems of low early strength, high cement consumption, poor economic efficiency and slow strength development of a mine filler, NaOH, Na2SO4, Na2CO3 and water glass were selected as alkali excitants, and the excitation effect of the four excitants on the activity of cement-slag cementitious material and the evolution law of mechanical properties of the filler were studied in comparison. The test results showed that the optimum values of 3d compressive strength were 1.36 MPa and 7d compressive strength were 2.26 MPa when NaOH was used as the exciter; the optimum values of 3d compressive strength were 1.33 MPa and 7d compressive strength were 2.11 MPa when Na2SO4 was used as the exciter; the optimum value of 3d compressive strength was 0.83 MPa when Na2CO3 was used as the exciter. The optimum value of 3d compressive strength was 0.83 MPa and the optimum value of 7d compressive strength was 1.74 MPa; the optimum value of 3d compressive strength was 1.42 MPa and the optimum value of 7d compressive strength was 2.35 MPa when water glass was used as the excitation agent. Na2CO3 was the least effective.
- 1
Study on Optimization of Key Parameters of Stage Open Stoping with Subsequent Filling MethodAbstract:
The continuous consumption of mine mining with shallow resources gradually develops.In order to select the optimal stope parameters and stoping sequence, FLAC3D software is used to analyze a certain mine’s calculation results of different stope spans, both sides of the first step are ore, and both sides of the second step are cemented backfills. The results show that the stress, displacement and plastic zone position distribution of 16m, 18m, 20m, and 22m are basically the same, in which the plastic span has a large plastic zone when the stope span is 20m and 22m.When returning to the pillar in the second step, the pillar span is 18m, 20 m and 22m, and the lower tensile stress of both sides exceeds the tensile strength of the cemented backfills, which can cause the region to be destroyed. Considering the actual situation on the spot, the stope span and the span span were finally selected to 16m, and the optimal stoping sequence is " taking one every the other one ". This study provides certain guidance on the deep mining of similar mines.
- 1
Research on stress evolution law and surrounding rock control of roadway under the influence of faultAbstract:
Aiming at the problem of High Stress Soft Rock Roadway,The deformation of surrounding rock is large and difficult to control.To analyze the main causes,Taking the comprehensive situation of auxiliary adit and return air roadway under the influence of fault in Nuodong coal mine as the engineering background.Under the influence of faults,a variety of support methods are used to support it,the effect is still not ideal.In view of this phenomenon,in this paper, field monitoring, theoretical analysis and numerical simulation are combined to analyze the roadway support and its effect.The main causes of roadway failure and deformation failure under the influence of faults are studied,under the influence of f04 and F05 fault plane on auxiliary adit.Using 3DEC discrete element numerical software, the numerical model is established, and the theoretical analysis method is used to analyze the stress nephogram and plastic zone range of the auxiliary adit passing through the fault, so as to clarify the cause of roadway deformation, and then analyze the failure mechanism of roadway surrounding rock. The new design scheme is used to construct the roadway, and the mine pressure data are compared before and after measurement.So we can draw a conclusion. The research shows that after using the system, the roof is reduced by 70% and the two sides are reduced by 74% compared with the traditional technology, so the deformation of roadway surrounding rock is greatly improved under the influence of faults.
- 1
Study on coal seam permeability characteristics of lower protective layer mining in Jiaozishan Coal MineAbstract:
In order to study the stress evolution and permeability evolution law of overlying coal seam in the lower protective seam mining, taking No. 8 and No. 9 coal seam in Jiao Zishan Coal Mine as the research objects, COMSOL was used to establish the coal seam excavation model, and the stress evolution law of the roof of the lower protective seam and the permeability changes of No. 8 and No. 9 coal seam were studied, and the field test was carried out to verify the results. The results show that with the continuous advancement of the protective layer, the stress concentration at the front end of the working face reaches about 8 MPa. When mining to 80 m, 8 coal permeability increased from 2.8 × 10-17 m2 to 4.0 × 10-17 m2, 9 coal permeability increased from 2.6 × 10-17 m2 to 16 × 10-17m2, increased by 71.67 % and 586.70 % respectively. 8 Coal gas extraction data show that protective layer mining increases gas extraction by about 14 times, and the peak flow of gas extraction reaches 35 m3 / min. After the protective layer was pushed forward 80 m, the coal seam cracks were closed due to the self-weight of coal and rock, and the gas extraction rate decreased to about 25 m3 / min. The borehole peep shows that the protective layer mining affects about 40 m coal and rock, and the results are consistent with the numerical simulation.
- 1
Exploration of weighted vibration level prediction methodconsidering elevation effectAbstract:
In order to explore the environmental vibration problems generated by open-air deep hole blasting. Based on step blasting test. The slopes with intact rock features were selected for vibration testing. The effect of horizontal distance and elevation difference on the lead hammer to weighted vibration level of environmental vibration evaluation was analyzed. The linear and nonlinear regression fitting method was used to construct a mathematical model of the weighted vibration level considering the elevation effect. The prediction results are compared with those of existing mathematical models. The results show that the attenuation characteristics of the weighted amplitude are characterized by the horizontal distance and elevation difference. The horizontal distance attenuates the weighted amplitude at a rate 0.023 dB/m faster than the elevation difference, the mathematical model of the weighted amplitude considering the elevation effect can predict the weighted amplitude more accurately. The prediction accuracy of linear and nonlinear mathematical models considering elevation effects is 0.88% and 0.96% higher, respectively, than the empirical prediction formula similar to the Sadovsky's formula.
- 1
The determination of grouting thickness around tunnel in broken surrounding rockAbstract:
Tunnel water inflow is a inevitable problem in tunnel engineering, and its accurate prediction is important to ensure safe construction. In this paper, taking a tunnel as a case, considering the fluid-solid coupling effect, the numerical simulation method is used to calculate the water inflow of tunnel and the pore water pressure distribution of surrounding rock for the condition of different water level and permeability coefficient, and then, the waterproof effect of grouting reinforcement range is studied by taking water inflow Q as the control standard. The results show that the water level is the main factor affecting the value of tunnel water inflow, in contrast, the permeability coefficient of surrounding rock has little influence on the seepage flow. At the same time,for the condition of V-grade surrounding rock, the selection of 4m thick grouting reinforcement circle can not only effectively prevent water inrush, but also save resources and costs. The research results provide technical support for the construction of a tunnel, and also provide reference for similar tunnels.
- 1
Research on the Interaction between the Dry Tailing Yard of Open Pit and the Bottom RoadwayAbstract:
Taking an open pit to form a phosphogypsum dry storage project as an example, after investigating the spatial distribution of the phosphogypsum reservoir area and the terrain roadway and using indoor rock mechanics experiments to obtain the required rock and soil mechanical parameters,According to the designed construction plan of the reservoir area, FLAC3D numerical simulation is used to analyze the safety impact of the phosphogypsum dry pile reservoir formed by the open pit on the existing underground tunnel engineering.The analysis results show that the design adopts the method of using open pits and storing dry phosphogypsum in stages, which has little effect on the stress and strain fields of the roadway at the bottom.The future mining of the bottom roadway will have little impact on the safe operation of the overlying phosphogypsum storage yard.Corresponding countermeasures are proposed for the design of safety facilities for dry storage of tailings in open-pit pits and their normal operation after construction.
- 1
Prediction of Surface Subsidence Coefficient Based on PCA-GA-SVM ModelAbstract:
Abstract：In order to solve the problem that the coefficient of land subsidence cannot be accurately predicted, this paper proposes a genetic algorithm (GA) optimized support vector machine (SVM) model based on principal component analysis (PCA) to achieve accurate prediction of the coefficient of land subsidence. The principal component analysis method was used to reduce the dimension of the seven surface movement parameter influencing factors in forty-five coal mining areas, and the new principal components were extracted. At the same time, the optimal penalty factor and the optimal kernel function that could optimize the support vector machine were obtained through the genetic algorithm. Parameters, input the principal components into the optimized support vector machine, and compare the difference between the predicted value and the true value of the obtained land subsidence coefficient. The results show that the average relative error of the PCA-GA-SVM model can reach 7.01%. Compared with the three models of SVM, PCA-SVM, and GA-SVM, the PCA-GA-SVM model has higher accuracy, and the model can be more accurate. Accurately predict the surface subsidence coefficient.
- 1
Experimental Study on the Inhibition of Coal Spontaneous Combustion by Transition Metal Ions in Inert CoalAbstract:
Abstract: In this paper, the effects of transition metal ions on coal spontaneous combustion were studied by combining theoretical analysis and experimental research. The transition metal ions in coal were chelated by 2-hydroxyphosphonylacetic acid (HPAA) as the inhibitor to reduce the activity of transition metal ions, which provided a new idea for the prevention and control of coal spontaneous combustion. The experimental results show that Fe3+ and Mn2+ can improve the oxidation activity of coal and promote the spontaneous combustion oxidation of coal to a certain extent. HPAA inhibitors can inhibit the release of CO gas in the process of coal spontaneous combustion oxidation, and the inhibition effect gradually increases with the increase of temperature. The experimental results of simultaneous thermal analysis show that the HPAA inhibitor can significantly increase the ignition temperature and the maximum thermal weight loss rate temperature in the process of coal spontaneous combustion oxidation, and reduce the maximum heat release power and total heat release.
- 1
Influence of wind velocity on heat accumulation inside coal pileAbstract:
In order to study the characteristics of coal spontaneous combustion due to oxidative heat storage and spontaneous combustion in the natural accumulation state, the effect of airflow velocity on spontaneous combustion of the coal pile. The COMSOL numerical simulation software was used to study the changes of the temperature field of the coal pile, the spontaneous combustion period of the coal pile under different airflow velocity conditions, and the migration of the coal pile spontaneous combustion high temperature area. The results show: after spontaneous combustion, its high temperature point will move to the bottom of the coal pile, and as the temperature of the coal pile increases, the high temperature point will gradually move to the upwind surface of the coal pile; 0.05 m/s is the critical value of airflow velocity, when the airflow velocity exceeds or below 0.05 m/s, the spontaneous combustion period of the coal pile is delayed. Secondly, the increase in airflow velocity will cause the internal spontaneous combustion range of the coal pile to gradually move from the windward side to the leeward side of the coal pile. The influence of airflow velocity on spontaneous combustion of coal piles is more complicated, and the spontaneous combustion period of coal piles can be delayed by reducing or increasing the airflow velocity.
- 1
Study on Ecological Compensation for Mineral Resources Exploitation: A Case Study of Manlailiang Mine in Inner Mongolia Autonomous RegionAbstract:
The purpose of this paper is to determine the proportion of compensation that mining enterprises should pay in different stages of mine ecological environmental damage, and to define the responsibility of each ecological compensation subject, which is the main means to mobilize the enthusiasm of stakeholders, and can provide a basis for the study of mine ecological compensation standard and model. Method of this paper is taking the Manlailiang Coal Mine in Ordos, Inner Mongolia as an example, using a variety of monetary value quantification method is expected to mines of ecological damage, using hierarchical analysis model can determine the ratio of mining enterprises shall pay compensation at the present stage, based on the principle of Shared responsibility adopted many regional input-output model analysis, ecological compensation responsibility. The results indicate that the estimated value of ecological environmental loss caused by the mining of Manlailiang coal mine is 165.8 million yuan, which is in the accelerated destruction stage, and the compensation ratio of mining enterprises is 16.20%. In conclusion, the central government shall undertake policy guidance and incentive work; mining enterprises shall contribute to compensate for and restore the ecological environment in time; local governments shall adopt compensation measures in accordance with local conditions and supervise the restoration work.
- 1
CHARACTERISTICS OF FINE SLAG FROM SHELL COAL GASIFICATION AND RECOVERY OF RESIDUAL CARBON BY FLOTATIONAbstract:
The high content of residual carbon from coal gasification fine slag restricts its use in building materials. The separation of residual carbon from fine slag by flotation is an effective way to improve its comprehensive utilization. In this paper, we choose a fine slag from Shell coal gasification in Datong as the research object, and firstly study its composition, particle size distribution, surface morphology, specific surface area and functional groups, and then study the recovery of residual carbon by flotation. The results showed that the ash content of fine slag was 36.07%, which was mainly composed of spherical glass, quartz, mullite and troilite. There was a loose and porous structure for the residual carbon with the specific surface area of 66.21 m2/g. The particle size was mainly distributed in the size fractions of 0.3-0.125 mm and -0.045 mm, and there was the low ash content for coarse size fraction, but the high ash content for fine size fraction. When a rough flotation with two stage reagent addition was used, and the diesel oil and 2-Octanol dosage were respectively 30 kg/t and 5 kg/t, a refined carbon with the yield of 83.61% and the ash content of 22.70% could be obtained, and the ash content of tail ash was 97.41%, which reaches the standard of first-grade fly ash. This research could provide a technical basis for the separation of residual carbon from fine slag.
- 1
Impact Evaluation and Prevention Research of Hunan Mine Geological Environment DestructionAbstract:
Using survey methods such as data collection, remote sensing to monitor and identify the geological environmental damage of mines in Hunan Province. The results show that mining activities have caused 38892 land damages in the province, covering an area of 45 872.7 hectares, of which building materials and non-metallic minerals occupy the most severely damaged land. A total of 807 geological disasters occurred in 465 mines, of which ground deformation, landslides and collapses mainly occurred in energy mines, accounting for 530, 29, and 10 respectively. Debris flows mainly occurred in non-ferrous metal mines with 21. The annual discharge of wastewater from 2296 mines in the province reached 355.6897 million m3, and 250 water environmental pollution occurred in 229 mines, polluting 676.3 hectares of water bodies. There are 2701 mines in the province discharging coal gangue, waste rock and tailings totaling 13.343 million m3. A total of 895 mines had soil and rock pollution, polluting an area of 5748.8 hectares. Using the comprehensive mine geological environment assessment method, 673 mines are classified as serious, 3197 mines are classified as heavier, and 6962 mines are classified as lighter. Through the remediation of the mine geological environment, the province is divided into 38 protection and remediation areas, including 20 key remediation areas, 17 key remediation areas, and 1 general remediation area. Finally, we evaluate the damage to the geological environment of mines in our province, and put forward targeted opinions to provide strong support for the construction of green mines and ecological civilization in our country.
- 1
Study on the influence of different train load simplification methods on the stability of adjacent foundation pitsAbstract:
In order to study the influence of the simplified method of train dynamic load on the stability of adjacent ground connecting wall, this paper takes the foundation pit support project of Taiyuan Taigang Iron and Steel"s car dumper system as the background, considers the effect of train dynamic load in the process of foundation pit excavation, and uses numerical values The simulation method, under the action of the simplified forms of different train loads, analyzes the wall side displacement and the adjacent ground settlement of the underground diaphragm wall project that undergoes step-by-step excavation, and compares it to the safety of each stage under different working conditions. A set of simulation data with higher coefficients, and record the corresponding load simplification methods, provide model calculation and load simplification ideas for such projects that need to consider train loads. The analysis results show that the train load has a significant impact on the settlement of the ground near the ground wall, and its impact range is about 1~10mm, and the difference is the largest near the train track. The influence range of the train load on the side displacement of the ground connecting wall is only -2~2mm, but its effect is more complicated than the settlement. When establishing the numerical model, it should be selected according to the actual construction conditions. Correspondingly, a more reasonable simplified form of train load.
- 1
Experimental study on optimal bearing compression characteristics of fly ash fractured gangue filling materialsAbstract:
In order to improve the waste rock solid packing materials such as bearing compression ratio, based on the lateral confined compression technology and the acoustic emission technology, design of lateral confined compression test and acoustic emission test, studied the bearing in the process of compression crushing waste rock under different stress state of the acoustic emission (AE) frequency, reveals the bearing compression crushing damage mechanism in the process of broken coal gangue, fly ash content on crushing waste rock filling materials are analyzed carrying the influence of compression ratio, the optimal dosage of fly ash.The research show that: as the stress gradually increases, the cumulative acoustic emission events also gradually increase, when the stress reach to 1-8 MPa, the number of acoustic emission generated by this stress section is higher, the gangue deformation damage is more serious; under the current test conditions, the best fly ash doping is 30%, the strain under 2MPa stress is 0.248, the bulk density is 18.67kN/m3, this conclusion has a great reference value for the popularization and application of mine filling.
- 1
Numerical simulation of deep ventilation and cooling system in Sanshandao Gold Mine Based on FLUENTAbstract:
With the deepening of mining depth of Sanshandao Gold Mine, the deep mining environment is more and more severe, and the heat damage caused by high temperature and high humidity has seriously affected the efficiency and safety of deep mining. In order to analyze and optimize the deep ventilation system of Sanshandao Gold Mine, the deep ventilation system model was established by investigating the underground deep thermal environment parameters and using ANSYS, Fluent and other numerical simulation software, and then, the distribution law of temperature field and flow field in deep mine is simulated and calculated. Aiming at the -960m level local ventilation cooling system, several groups of ventilation system transformation schemes are designed for simulation calculation. Through analysis and comparison, the ventilation and refrigeration parameters of underground system ventilation cooling and working face local cooling are obtained, which provides a reference for deep system ventilation and local cooling.
- 1
Research on the Seepage Law of Solution in the Blind End of Meso-Leaching Based on PIVAbstract:
To reveal the law of solution seepage in the leaching blind end structure, based on the particle image velocimetry (PIV) technology, a physical model of the blind end structure of uniform liquid distribution was established, and the solution of the meso blind end structure under the conditions of different spray intensities and inflow angles was developed Percolation experiment. The PIV technology is used to obtain the instantaneous displacement image of the tracer particles in the solution, and the cross-correlation algorithm is used to obtain the flow velocity vector distribution diagram and the vorticity distribution diagram in the blind end structure. The results show that the solution distribution in the blind end structure is obviously different. The solution flows quickly outside the blind zone and swirls flow inside. The flow field parameters in the blind zone are positively correlated with the spray intensity and the inflow angle of the solution. When the spray intensity increases from 20L/h to 40L/h, the extreme value of the flow velocity in the blind zone increases by 250%, and the vorticity increases by 216.4%; When the inflow angle is increased from 45° to 90°, the extreme value of the velocity in the blind zone increases by 75%, and the maximum vorticity increases by 108.4%.
- 1
Study on pretreatment of gold bearing pyrite by H2O2 oxidationAbstract:
Based on Fenton reaction, the effects of initial concentration of H2O2, temperature, initial acidity, pulp concentration, H2O2 synergistic persulfate and different activators on the oxidation leaching of pyrite were studied. The results show that pyrite is dissolved in H2O2 oxidation system, the concentration of pulp is 10 g/L, the concentration of H2O2 is 6%, the concentration of sulfuric acid is 0.24 mol/L and the leaching rate of pyrite reaches 94.05% after 5 h of reaction. The apparent activation energy of pyrite oxidation leaching is 12.31 kJ/mol at 25 ℃ ~ 70 ℃, a diffusion controlled nuclear shrinkage model for solid reaction.
- 1
Research on Formation of Underground Multi-mobile Robots Based on Leader-Follower StrategyAbstract:
Multi-robot cooperative queuing is an important direction of the future development of robot technology. Compared with a single robot, the multi-robot cooperative queuing can complete complex tasks that a single robot cannot complete. In order to improve the effect of formation control and the efficiency of execution for multi-mobile robots, puts forward and designs an improved navigation following first-order consistent formation algorithm based on the consistency theory. The simulation results show that the method has a small error range and high practicability, the results can be used in the research of multi-inspection robot formation in coal mine.
- 1
Experimental Study on Strength Evolution of Filling Body under Stress CuringAbstract:
The ratio parameters of filling materials and the strength of filling body are important indicators for studying the filling mining method. The conventional indoor filling test cannot simulate the in-situ environment of filling stope and the influence of multiple factors on the strength development of filling body, and cannot obtain the strength and material ratio parameters of filling body that match the engineering environment. The multi-field coupling curing test instrument of filling body was used to simulate the strength evolution law of filling body under deep stress conditions with filling body materials and filling body strength as the research objects. It is found that the strength of the filling body increases with the increase of maintenance stress, and the influence of maintenance stress on the late strength of the filling body is significantly greater than that on the early strength of the filling body. Under the same mix ratio, the strength of the filling body under pressure maintenance and conventional maintenance is quite different,The strength of filling body with pressure curing at 14 days is 15.4% higher than that of conventional curing. The main factors affecting the strength development of filling body under pressure maintenance are pore water and maintenance stress.
- 1
Law and mechanism of the influence of water content on the tensile strength of deep rockAbstract:
"Deep rock mechanics and mining theory" has been included in the national key research and development project during the 13th Five Year Plan period. In order to enrich the deep rock mechanics and theory and guide the exploration and development of deep coalbed methane, the tensile strength characteristics of fine sandstone, mudstone, coal and medium sandstone under different water bearing conditions in Yushe Wuxiang block are studied, The results show that: through the free water absorption test, the water absorption of deep rock has no obvious change after 5 days, the saturated water absorption of coal is the highest, which is 6.13 %, and the saturated water absorption of fine sandstone is the lowest, which is 0.68%; The tensile strength of fine sandstone, mudstone, coal and medium sandstone decreases by 72.21 %, 54.98 %, 77.48 % and 68.60 % respectively under the condition of saturated water. The decreasing form is a negative exponential function. The effect of water on coal is the most sensitive. When the water saturation is 50 %, the tensile strength loss is 58%, while that of fine sandstone is only 14 %; With the increase of water content, it is found that the tensile strength of mudstone, coal and medium sandstone decreases first and then slowly, while the tensile strength of fine sandstone decreases first and then slowly; In the stress displacement curve, the fine sandstone, mudstone and medium sandstone in dry state show typical brittle failure, while the coal shows static failure. With the increase of water content, the rock has the trend of transition from brittleness to ductility; In the failure diagram, there are obvious differences in the failure modes of the same kind of rock under different water content states. Under the water content state, there are more crack propagation paths. For fine sandstone and coal, in addition to the main crack penetrating through the center of the circle, there are several new associated cracks penetrating through the main crack or the end face loading. For mudstone with 1.66% water content, the crack propagation paths of the same kind of rock become more and more, For medium sandstone, there will be a crushing triangle at the loading end.
- 1
Study on damage evolution characteristics of coal samples under acidic water environmentXUE Huifeng, 张元, 姚田
Abstract:
The structural characteristics and mechanical properties of coal in acidic, alkaline or neutral water environment have different effects. To study the characteristics of strength damage and chemical corrosion of coal in acid environment, acoustic emission (AE) and uniaxial compression tests were used to investigate the chemical corrosion of 50 mm × 100 mm cylinder coal specimens were tested. The results show that the porosity of coal increases, the uniaxial compressive strength and elastic modulus decrease, but the peak strain increases after chemical corrosion compared with the coal with pH = 7 water. Acid solution accelerates the weakening of coal, and the structure of coal still releases more energy in the process of destruction. The average strength of the sample soaked in the solution of pH 2, 4, 6 and 7 is 7.92, 10.85, 12.95 and 12.90 MPa, which indicates that the stronger the acidity is, the more serious the damage is. The strain energy and dissipated energy of the coal sample have similar characteristics with the change of different pH values with the increase of strain. Under continuous loading, the total energy of coal specimen increases continuously, and the increasing speed changes from slow to fast to slow. The releasable elastic strain energy increases gradually before the peak stress, and decreases gradually after the peak stress. The research results provide guidance for coal weakening, roadway support and chamber coal pillar stability.
- 1
Research on the Accuracy of Tilt Photogrammetry data in Mine MiningAbstract:
Along with our country mining of wisdom degree deepening, the traditional measurement methods cannot meet this set of big data, cloud computing, artificial intelligence technology such as intelligent system based on the demand of the data acquisition speed and efficiency, therefore, put forward the unmanned aerial vehicle (uav) tilt photography measurement methods for data collection, mining in calculation of earthwork quantity, for example,Verify the accuracy, high efficiency and the feasibility of the acquisition method.Modeling model is completed after compare the measured value and the actual measurement value by analyzing the absolute error and relative error curve to determine the size of the error and the source, in the case of two-dimensional data are more accurate, choose different size of grid, the pile has a larger volume changes, to further determine the edge of the volumetric error from the model belongs to the model error,Through the comparative analysis of ten data sets, the optimal mesh size was determined, which was about 2 m before explosion and about 1.2 m after explosion.The final results show that UAV tilt photography can quickly and accurately obtain the information of blast mound shape and carry out the precise calculation of length, area and volume, which realizes the engineering requirements of high efficiency and low cost, and provides a convenient, fast and efficient new method for the engineering survey of complex terrain in open-pit mines.
- 1
Potential Evaluation of Reclamation for Grassland in Open-pit Mine Based on Game Theory and Matter Element ModelAbstract:
For the purpose of effective evaluation on land reclamation potential of open-pit mines, the evaluation index system of reclamation potential was established by eleven factors (including the terrain, the soil conditions, the mean annual precipitation and the social economic level, etc.), which were further selected from four aspects such as the stope topographic conditions, the soil conditions, the climatic and hydrological conditions, and the social and economic conditions. Then, a model for land reclamation potential evaluation of open-pit mines based on game theory and matter-element model was established. In this model, the game theory was used to calculate the subjective and objective weights to get the comprehensive weights, and the matter element theory was utilized for the classical domain and node domain determination. Finally, the evaluation model was applied to the Dingxiangshan limestone mine in Guigang, Guangxi; the potential membership degrees and comprehensive membership degrees of the three units in the mine, which were reclaimed as grassland, were calculated by the MATLAB software, respectively. According to the results in this mine, it can be showed that the potential evaluation grades of the stope step platform and stope bottom platform that were reclaimed as grassland were "extremly good", while the potential evaluation grade of aggregate industrial site reclaimed as grassland was "good". The evaluation results are consistent well with the fact.
- 1
Study on the stability of floor during the whole process of “twice excavation and mining” along filling bodyAbstract:
As a non-renewable resource, how to improve the recovery rate of coal under the condition of safety has always been a hot research issue. Firstly, this paper briefly summarizes the research progress of gob-side entry retaining and gob-side entry driving. On this basis, a new type of mining technology without coal pillar is introduced, that is, pre-filling in the roadway without coal pillar (Roadway driving along the backfill), and the roof stress distribution law of “three stages” is expounded. The stability of floor during the whole process of “twice excavation and mining” is analyzed by numerical simulation. The results show that the backfill always maintains a high stress state during the whole process of “twice excavation and mining”, the rock mass around the roadway has undergone repeated loading and unloading, and the peak abutment pressure of backfill and solid coal wall appears alternately. Among them, at the mining stage of the second working face, the peak values at the backfill wall and solid coal wall both reach the maximum values, which are 24.2 MPa and 27.2 MPa respectively, and the floor heave reaches the maximum value of 321.8 mm at 5 m away from the working face.
- 1
Mineralogy and flotation technology of a Gold-Silver Associated Lead-Zinc oreAbstract:
A lead-zinc ore contains 2.96% Zn, 0.85% Pb, 0.13% Cu, 1.01g/t Au and 33.70g/t Ag. The beneficiation plant treated it as a lead-zinc ore. Associated metals such as copper, gold and silver had not been comprehensively recovered. As process mineralogy reveals, sphalerite is the main mineral of zinc. Its particle size is coarse and the inter-relationship is simple, which is benefit to flotation. The theoretical Zn recovery is 97.84%. Galena is the main lead mineral, followed by sardinianite and cerusite. Galena is closely related to sphalerite, and some is covered by sardinianite due to oxidative alteration, which affects the flotation of lead. The lead theoretical recovery is 88.32%. Silver is mainly contained in free silver minerals and galena, and can be floated together with galena. The silver theoretical recovery is 72.81%. Gold mainly exists in the form of bare gold and sulfide ores, which are closely related to silver minerals and can be floated with silver and lead. Copper is mainly contained in chalcopyrite, which is closely related to sulfide ore and has fine particle size and low grade. Its floatability is similar to that of galena, and it can be recovered with galena flotation. Based on the characteristics of the ore, the technology of "rough grinding-lead priority flotation-zinc-sulfur bulk flotation-zinc-sulfur separation" was formulated. GW-221 was used as the collector of lead, copper, gold and silver to strengthen the collection of gold and silver. Good flotation index have been obtained, and the lead concentrate contains 24.73% Pb, 3.71% Cu, 558.64g/t Ag and 13.52g/t Au, and the recovery are 77.69%, 76.24%, 44.26% and 35.74% respectively. Zinc concentrate contains 48.99% Zn, Zn recoverey is 89.56%. Lead, zinc, copper, silver and gold have been comprehensively recovered. Subsequent recovery of free silver minerals and gold needs to be strengthened to increase the silver-gold recovery.
- 1
Study on the influence mechanism of ground fissures in the affected area of Fushun West open pit mine on the proposed comprehensive utility tunnelAbstract:
In order to explore the impact of ground fissure activities on the proposed underground utility tunnel structure, the comprehensive utility tunnel structure passing through No. 1 ground fissure in the affected area of Fushun West open pit mine is taken as the research object, combined with the field monitoring data, ABAQUS finite element software is used to analyze the deformation and stress characteristics of underground utility tunnel structure under the action of ground fissure dislocation. The results show that: the vertical and horizontal displacements of the utility tunnel increase with the increase of the dislocation of the ground fissure. The deformation zone of the utility tunnel is in the range of 50 m from the hanging wall to the ground fissure and 45 m from the footwall to the ground fissure; The vertical deformation of the underground utility tunnel shows an inverse "s" shape under the action of the ground fissure dislocation; When the cumulative displacement of local cracks is 50 cm, the horizontal displacement of the utility tunnel reaches the peak at the ground fissures, the peak of the horizontal displacement of the roof is 4 cm, and the peak of the horizontal displacement of the floor is 3 cm; Under the action of ground fissure dislocation, the top plate of the utility tunnel located in the footwall is compressed and the bottom plate is tensioned, while the top plate of the utility tunnel located in the hanging wall is tensioned and the bottom plate is compressed; When the ground fissure dislocation exceeds 20 cm, the axial strain of the top and bottom of the utility tunnel far exceeds the specified strain value, and the tensile failure is the main deformation failure mode of the utility tunnel The axial stress and strain of the utility tunnel structure caused by the dislocation of ground fissures can be significantly reduced by setting flexible joints in sections. The research results can provide a scientific basis for the structural design of Fushun underground utility tunnel crossing the ground fissure zone.
- 1
Research on the Risk of Global Copper Supply Chain Based on Complex NetworkAbstract:
In order to identify the risk of copper supply chain, a complex network of mines, refineries, shareholders and countries is constructed, and the supply risk is studied from the perspective of network structure. The results show that: in the copper supply chain data analysis, the supply interruption of a single country will not cause the global copper resources supply crisis, and the supply chain risk is low. In the network analysis, the fluctuation of supply in a single country will lead to the change of network structure, and other participants in the copper market will inevitably bear the risk brought by the change of network structure. In the supply network, China lacks multinational companies that can integrate global copper resources. In the trade network, it is difficult for China to form influence on major resource exporting countries, and the supply chain risk is high.
- 1
FIRE PREVENTION AND EXTINGUISHING IN GOAF AND SEALING TECHNOLOGY OF WORKING FACE END IN HIGH GAS MINEAbstract:
Aiming at the problems of spontaneous combustion of residual coal in goaf of high gas mine and gas overrun caused by lax end sealing of working face, the defects of commonly used goaf fire prevention and extinguishing technology and end sealing method are analyzed, and the underground fire extinguishing technology of superhigh water material and end sealing method of superhigh water material pumping and bagging of working face are put forward, which are successfully applied in main coking coal mine. The working time is reduced by 50%, the labor efficiency is improved, and the working environment is improved, and provides technical support for the green, safe and efficient mining of the mine.
- 1
Static Classifying Experiment of Eddying Classification Column with Mesh Diameter of D0.15mmAbstract:
Combining sieve classification with hydraulic classification, the author invents a classifying equipment, Eddying Classification Column, which has higher classification accuracy and efficiency. In this paper, by studying the Eddying Classification Column, the influencing factors and coupling relationship of the classification efficiency of the equipment are explored. The test shows that the particles can reach the grading balance in a short time. In the grading test, the particle grading has been basically completed within 5 seconds, and the particle grading efficiency has been improved very little after that. Besides, the classification efficiency decreases when the ore concentration increases. Moreover, the increase of the blade speed will increase the particle classification efficiency, while the increase of the blade γ azimuth angle will reduce the particle classification efficiency.
- 1
New Development of “intelligent filling” enabling mineAbstract:
The backfilling system of Shandong Gold Group has accumulated a large amount of experimental and industrial data. Due to the lack of data management, a large amount of data can not provide effective decision support for the production and operation of mines, the traditional automatic filling control system is difficult to realize the self-optimization of filling process parameters. In view of the above problems, the paper first analyzes the development direction of the current filling intelligent control system, and puts forward the concept of "intelligent filling" , SQL, Javascript, HTML, LAD and other programming languages, the "intelligent filling" system, which includes intelligent control of filling and data integration management, is designed. The results show that the intelligent filling system can reduce the filling cost, improve the filling efficiency, promote the intelligent transformation and upgrade of the filling process, and accelerate the ecological, intelligent and efficient development of the mine.
- 1
Application of BP neural network optimized by particle swarm optimization in slope stabilityAbstract:
The factors affecting slope stability are complex and changeable, which brings difficulties to the evaluation and prediction of slope stability. Neural network can obtain complex nonlinear relationship from sample data through self-learning function, which is suitable for solving the problem. Therefore, The structure of feedback forward neural network is set up by Python using particle swarm optimization algorithm. The network is established to realize the analysis of slope deformation data, and learning quality, training speed and prediction accuracy are improved. Six main factors such as soil weight, cohesion and internal friction angle and so on are selected as evaluation indexes. The prediction results of the neural network model are compared with the actual data to prove the rationality and effectiveness of the model. This paper discusses the feasibility of solving traditional practical engineering problems based on artificial intelligence programming language, and provides reference and guidance for the the integration trend of future development of the industry and the intelligent language.
- 1
Design of Busbar Spiral Blade of Vertical Screw Elevator Based on DEM-FEM Co-simulation AnalysisAbstract:
This paper studies the problem of the lack of theoretical basis for the design of the generatrix function of the spiral blade when the vertical screw conveyor conveys mineral powder. The transportation efficiency, maximum deformation, and stress distribution are used as the evaluation criteria for whether the structure is reasonable. A preliminary design of a new type of spiral blade is carried out using the single-mass point theory, and an algorithm for evaluating the accuracy of the EDEM periodic model based on the particle porosity is proposed. The EDEM model was established and simulated and compared with the calculation results of the single-particle theory. The results show that the single-particle theory can only roughly represent the particle movement change trend, and it is difficult to accurately reflect the actual movement change; for 45%, 1200rpm working condition The DEM-FEA joint simulation analysis of the vertical screw conveyor underneath shows that the maximum stress load and maximum deformation of the inclined straight busbar spiral blade in the vertical screw conveyor are significantly less than the traditional horizontal straight busbar spiral blade. Provide a reference for the design of the blade structure of the subsequent vertical screw conveyor.
- 1
Real-time and High-precision Positioning Method for Underground Patrol RobotAbstract:
In view of the special geological environment in the underground roadway of coal mine, a mine integrated navigation positioning system based on strap-down inertial navigation (SINS) and modified by radio frequency identification (RFID) is proposed. The error caused by time and distance accumulation of the strap-down inertial navigation system is calibrated by the actual location information stored inside the radio frequency tag.The extended Kalman filter technology is used to fuse the data in order to reduce the cumulative error of inertial navigation, thus completing the high-precision positioning research of patrol robot.
- 1
Simulation of Stirring for High-concentration Filler Slurry Based on the Coupled DEM-SPH MethodAbstract:
The simulation method based on the coupling of discrete element method (DEM) and smooth particle hydrodynamics method (SPH) is used to simulate the mixing process of the solid-liquid two-phase mixed medium of high-concentration filler slurry, and the effect of different mixing structures on the mixing effect of the slurry is studied. The simulation results show that increasing the blade diameter, the number of blade groups, and the number of mixing shafts can improve the uniformity of the mixing of materials. Among the 5 groups of mixer solutions with different structures, the double-shaft mixer has the shortest mixing time (180s) to achieve a uniform effect, and can achieve the maximum production capacity without increasing the size of the mixer, which is suitable for high-efficiency production of large-scale mines and large-flow filling systems.
- 1
Stope Structure Optimization for Yanqianshan Iron Mine Based on OrthogonalAbstract:
Aiming at the problem of low production efficiency and serious ore loss and dilution of sublevel caving method, the stope structure of sublevel caving method was optimized based on the orthogonal test method, so that the stope structure can adapt to the flow law of the ore and rock, so as to reduce the loss and dilution and improve the economic benefits of the mining enterprise. Taking sublevel height, drift spacing, caving spacing and drift width as factors, and taking ore loss rate, ore dilution rate and mining accuracy coefficient as indexes, the orthogonal test scheme of stope structure optimization for sublevel caving method is established. According to the orthogonal test scheme and the characteristics of the -213 m to -303 m in the eastern orebody of Yanqianshan Iron Mine, the ore drawing model of the stope was designed and made at a scale of 1:100, and the physical test of ore drawing was carried out. Analysis of range and variance showed that the order of factors affecting ore loss rate is caving spacing, sublevel height, drift spacing, drift width; The order of factors affecting ore dilution rate is sublevel height, caving spacing, drift spacing and drift width; The order of factors affecting the mining accuracy coefficient is caving spacing, sublevel height, drift width and drift spacing, and it is recommended to use caving spacing and sublevel height as the main factor when designing and optimizing the stope structure. Combined with the actual production situation of Yanqianshan Iron Mine and the test results, the optimal stope structure of -213 m to -303 m are designed as follows: sublevel height 22.5 m, drift spacing 26 m, caving spacing 2.3 m and drift width 7 m.
- 1
Application test of induced caving technology in formation of overburden layer for sublevel caving method in West No.2 Mining Area of Longshou MineAbstract:
When the West No.2 Mining Area of Longshou Mine in Jinchuan changes from downward slicing cemented filling method to sublevel caving method, large area cemented filling body roof is needed to caving form overburden. Through the analysis of the applicability of several commonly used methods of formation of overburden in the West Second Mining Area, the induced caving technology is selected as the formation method of the overburden in the West No.2 Mining Area. Then, the paper analyzes the risk of cemented filling body and overlying rock, and makes a specific implementation scheme of induced caving combined with the actual situation of the West No.2 Mining Area. During the implementation of the technical scheme, micro seismic monitoring, on-site tracking observation and surface settlement monitoring are used to monitor the caving process of stope roof. The monitoring results show that the use of induced caving technology in the West No.2 Mining area can make the cemented filling body of the stope roof fall safely and smoothly and form the overburden, which lays a good foundation for the successful transition from filling method to caving method in the West No.2 Mining Area, and has reference significance for similar mines.
- 1
EXPERIMENTAL STUDY ON OPTIMIZATION OF PASTE FILLING RATIO OF FINE TAILINGSAbstract:
For fine all in a certain gold mine backfilling strength of paste filling of the filling body is low, and strict mining wastewater discharge, etc., in a certain mine filling system, for example, backfilling materials of fine grained all the chemical and physical properties tests, flocculating sedimentation experiment, liquidity, ratio of strength calculation and analysis, obtained in a mine is suitable for best filling ratio parameter. The results show that the relative density of total tailings is 2.72 g/cm3, and the content of -20 μm ultrafine particles reaches 45.91%. After 6h of flocculation settlement, the bottom flow concentration can reach 65.3%, and after 20h of settlement, the bottom flow concentration can reach 73.2%, which meets the requirement of filling ratio concentration. Under the same ratio of cementitious material, PO425 cement has better fluidity and higher uniaxial compressive strength than M325 cement.The upward-facing slab-filling mining method is adopted. When backfilling, the PO425 cement concentration is 67%, the cement-sand ratio is 1:8, and the seven-day strength can reach more than 0.3MPa, which meets the self-supporting requirements of backfilling body. When pouring face filling, the PO425 cement concentration is 67%, the cement-sand ratio is 1:4, and the seven-day strength can reach 1.2MPa, which can meet the requirements of equipment operation. The concentration of heavy metal ions in the leachate of the backfilling slurry that meets the strength requirements conforms to the national discharge standard, and mine water can be used for paste backfilling ratio.
- 1
Optimization of Magnesium Removal Test of Collophane by Response Surface MethodologyAbstract:
A medium and low grade siliceous magnesium collophane in Yunnan has fine disseminated particle size, which belongs to fine collophane. Its useful mineral is mainly fluorapatite, which is mainly associated with dolomite, and the content of conjunct is 26.23 %. The effects of pH value, sodium hexametaphosphate dosage and saponification fatty acid dosage on magnesium removal were investigated by single factor experiment, and the magnesium removal conditions were optimized by response surface methodology. The results of single factor test showed that sodium hexametaphosphate and pH value had significant effects on the P2O5 grade and recovery rate of phosphate concentrate, while saponification fatty acids had little effect on the index of phosphate concentrate within the experimental dosage range. The optimum conditions obtained by response surface methodology were pH 5.84, sodium hexametaphosphate dosage 2.71 kg/t, saponification fatty acid dosage 0.87 kg/t. Under this condition, the indexes of phosphorus concentrate with P2O5 grade of 26.47 %, recovery rate of 87.95 % and impurity MgO content of 0.54 % were obtained, which were basically consistent with the optimized prediction results. It proves the reliability and accuracy of the response surface method prediction model.
- 1
Characteristics and Pollution evaluation of fluoride and sulfide in Plateau Alpine Open-pit Mining areaAbstract:
In order to clarify the influence of fluoride and sulfide on soil remodeling, selects the soil around the Muli open-pit mine in Qinghai Province as the research object. 29 soil samples around 9 mining pits were collected at the Juhugeng mining area, Dosogongma mining area and Jiangcang mining area. At the same time, 25 meadow soil samples were collected in the periphery of the mining area. Analyze the content of fluoride and sulfide in the soil, and evaluate the pollution of fluoride and sulfide by single factor index, Nemerow composite index and geoaccumulation index method. The results shows that the content of fluoride in the soil around the mine pit is far greater than the swamp meadow soil, with an exceeding rate of 72.4%, sulfide content is lower than swamp meadow soil. Fluoride is more sensitive to mining activities and coal gangue accumulation, and has a certain degree of enrichment and accumulation effects. The evaluation results shows that sulfide in the soil of the Muli mining area is within the clean and safe range, fluoride is within the safe range as a whole, and some mining pits have signs of slight pollution. In the process of using slag and coal gangue as raw materials for soil construction, attention should be paid to improving the environmental capacity of the soil for fluoride, anti-soil sulfide oxidation and fluoride leaching cause deterioration of the soil environment.
- 1
Investigation of the Interaction between Low-rank Coal and Mineral Particles in Flotation ProcessAbstract:
Because the surface of low-rank coal is covered by abundant oxygen-containing functional groups and the inner and outer surface pores are developed, the amount of collector consumption during the flotation process is high. In order to explore the influence of different types of mineral particle covering on the flotation behavior of low-rank coal in flotation process, the surface potential of four mineral particles and flotation concentrate are analyzed by laser particle size and electrokinetic potential measurements. Four minerals, quartz, kaolinite, montmorillonite and illite are selected during the flotation experiment. The experimental research results show that under the low mixing ratio of minerals with low-rank coal particles, the positive charge on the montmorillonite lattice produces a cover on the surface of the low-rank coal, thereby improving the flotation recovery; while at the medium or high mixing ratio, the flotation performances are depressed by the four minerals. The flotation concentrate yield of low-rank coal is severely inhibited at a high mixing ratio because quartz sand inhibits the flotation of low-rank coal most seriously by the maximum mechanical entrainment in the flotation process. The covering behavior of mineral particles on the surface of low-rank coal has an adverse effect on its flotation response.
- 1
Study on Thermal Damage Characteristics of Similar Overburden Materials in Underground Coal GasificationAbstract:
In order to carry out the three-dimensional similar simulation model test of underground coal gasification, the thermal damage characteristics of similar overburden materials were studied. The mechanical properties and thermal damage characteristics of similar overburden materials treated at different temperatures were studied by uniaxial compression test. The results are as follows: after heating, the diameter of each specimen increases slightly, the height increases and decreases, and the mass and density decrease; the stress-strain curves of the specimens after high temperature treatment usually go through four stages: pore compaction stage, elastic deformation stage, fracture stage and failure stage; the compressive strength of the specimens decreases with the increase of temperature; after the specimens are treated at 600 ℃, the compressive strength of similar specimens of coarse sandstone decreases from 1.61 MPa to 0.622 MPa by 61.38%, and the elastic modulus decreases from 0.29 GPa to 0.12 GPA by 59.4%; the compressive strength of similar fine sandstone specimens decreased from 1.34 MPa to 0.65 MPa by 51.57%, and the elastic modulus decreased from 0.28 GPa to 0.12 GPA by 56.7%; the elastic modulus is selected to define the damage variable; the thermal damage evolution of the specimen has a threshold at 100 ℃; before this threshold, the thermal expansion of the specimen particles is only used to fill the pores and fissures existing in the specimen itself; only when the pores and fissures in the specimen are completely closed under the action of temperature can the damage be revealed.
- 1
Study on the Changes of Ecological Environment Quality of Mining City Based on Improved RSEI Modelhuangjin, 周皓, 梁雅琪, 杨金凤, 刘艳中, 杨梅
Abstract:
Remote sensing based ecological index (RSEI) model has been applied increasingly to study the evolution of regional ecological environment quality. However, RSEI model also has some shortcomings, such as green degree, humidity, dryness, heat index and coupling RSEI values are not necessarily comparable in different years.In order to solve the problem, this paper selects the pseudo-invariant features as the benchmark to conduct annual correction of the index value, and carries out multi-period comprehensive principal component analysis of the revised index value, and establishes a unified RSEI evaluation model between different years.The results of ecological and environmental quality change in Daye City from 2013 to 2018 show that :(1) The mean values of RSEI was 0.571 and 0.536 in 2013 and 2018,which were both at average level and decreasing.(2) The areas with improved ecological and environmental quality are distributed along the northwest mining area, the northern old urban area and expressway,which are mainly benefited from the ecological restoration of mining area, the greening reconstruction of the old urban area and the natural restoration around the transportation land.The deterioration of ecological environment quality was mainly caused by the increase of construction land in Daye City and the expansion of towns and villages.(3) According to the buffer analysis, the impact range of the mining area on the ecological environmental quality is about 4km, and with the increase of buffer radius, the ecological environmental quality gradually gets better.
- 1
RESEARCH ON PRESSURE RELIEF CONTROL AND SUPPORT TECHNOLOGY OF DEEP HIGH STRESS ROADWAYAbstract:
Through theoretical derivation, numerical simulation, field test and other methods, the pressure relief and support problems of deep impact high stress roadway are studied. The stress distribution law of pressure relief borehole and the analytical solution of pressure relief control area of high stress roadway are theoretically deduced. The radius of fracture softening zone is mainly affected by the radius of pressure relief borehole and high ground stress, The coal and rock mass around the pressure relief borehole are fractured under the action of high stress in the roadway, forming the fracture softening, weakening the high stress, transferring the high stress, and realizing the stability of the roadway. The diameter of the pressure relief hole, the stress distribution characteristics of the roadway before and after the treatment of the pressure relief hole and the variation law of the surrounding rock of the roadway are studied by numerical simulation. Considering the power of the drilling rig and the roadway support, the diameter of the drilling hole is generally between 110mm and 130mm. The coupling support technology of "pressure relief control + yield support" and pressure relief hole protection technology are proposed to improve the integrity of roadway support. After the field test of new supporting, the maximum deformation of roadway side is 350 mm, the maximum deformation of roof is 171 mm, the range of roadway surrounding rock fracture is significantly reduced, compared with the original support, there is no overall instability phenomenon in the roadway. This technology can effectively control the deformation of high stress roadway and realize the stability of coal and rock mass in high stress roadway. The research results provide theoretical guidance and practical significance for pressure relief control and yielding support of high stress roadway.
- 1
The Correlation Effect of China’s Industrial Sector Carbon Emissions: An Analysis Based on Hypothetical ExtractionAbstract:
This article uses the input-output table of 42 industries across the country in 2017 and the energy consumption in 2017 as data. Using the "General Principles of Comprehensive Energy Consumption Calculation", the carbon emissions and carbon emissions intensity of 11 industrial groups were calculated. Hypothetical extraction method (HEM) analyzes the total carbon correlation, forward carbon correlation, and backward carbon correlation between industry groups. And decompose the correlation effect into internal effect, mixed effect, net backward effect, net forward effect and net transfer. The results show that the total carbon emissions and carbon emissions intensity of petrochemical metal manufacturing and electricity, water, and gas production and supply industries are the largest, and the net output carbon emissions are serious; the construction industry and the mechanical equipment manufacturing industry have more net carbon emissions. At present, my country's energy consumption structure is unreasonable, and primary energy sources such as coal still occupy a major position. Although the country has vigorously developed clean energy in recent years, it has always accounted for a low proportion and low utilization rate. Therefore, optimize the national energy consumption structure, improve the efficiency of primary energy use, and increase the proportion of clean energy consumption. So as to slow down my country's carbon dioxide emissions, it is urgent
- 1
Research on Comprehensive Mechanized Mining and Application of BauxiteAbstract:
In view of the low recovery rate of traditional underground bauxite mining methods, low mechanization, and serious ore dilution, Guodian Construction Investment Zunyi''s Wachangping bauxite mine combined with ore and rock conditions to learn from the comprehensive mechanized mining method of coal mines. An industrial test of comprehensive mechanized mining of underground bauxite was carried out. This paper studies the operation of mining machines, scraper conveyors and hydraulic supports in the process of bauxite mining comprehensive mechanized working face, and analyzes the production technical indicators. The research shows that the work interview is due to the "three machines" equipment at the working face in the early stage of mining. The selection and production organization are unreasonable, and there are phenomena such as working face equipment damage and severe wear of parts. After optimizing the performance of the “three machines” equipment and production organization and management of the working face, the bauxite fully mechanized mining face can achieve an average daily average of 5 dollars , The output is nearly 2,100 tons. Calculated by 330 days a year, the production scale can reach 693,000 tons per year on a single side, and it has reached the expected goal of the fully mechanized mining test. The comprehensive mining test carried out by the Wachangping bauxite mine of Zunyi Company proved that the comprehensive mining technology is technically feasible, safe and reliable. It is a major change and innovation in the mining technology of bauxite mines, and it has changed the mining method for traditional bauxite mines. The method to set an example is the development direction of safe and efficient mining in non-coal mines.
- 1
Study on Influence of Buried Depth on Surrounding Rock and Primary Support Deformation of Shallow Buried Large Section Hydraulic TunnelAbstract:
Taking a drainage tunnel in Linhai City, Zhejiang Province as the research object, the finite difference software FLAC3D was used to establish an analysis model to analyze the influence of tunnel burial depth on the excavation deformation of shallow buried tunnel under the condition of primary support, and the results were compared with the field monitoring data.The results show that :(1)Along the direction of excavation, the deformation of surrounding rock can be divided into three stages in space:the first stage of deformation in front of the face, the stage of deformation acceleration, the stage of deformation stability, and the increase of tunnel buried depth, the amount of deformation in the three stages also increases;(2)The variation rate of vault settlement is greater than that of horizontal convergence, the influence range of tunnel burial depth on vault settlement and horizontal convergence remains unchanged, and the transverse deformation of tunnel is not affected by tunnel burial depth;(3)The force of the bolt is distributed symmetrically along the axis of the tunnel, and the force of the bolt is the largest in the vault. The force of the bolt increases with the increase of the buried depth of the tunnel; The stress of lining is larger at the side wall and the corner, and the maximum deformation of lining occurs at the vault. With the increase of the depth of tunnel, the stress and deformation of lining increase somewhat;(4)The field monitoring results of the deformation of surrounding rock and the anchor stress of the tunnel were compared with the numerical simulation results. The field monitoring results were basically consistent with the numerical simulation results, which verified the accuracy of the numerical simulation.In actual engineering, reasonable and economical protective measures should be made according to the actual situation of construction site and different tunnel buried depth, especially the secondary support should be added in time for the vault part.Therefore, it can provide theoretical basis for similar projects to master the deformation law of surrounding rock under different buried depths of shallow tunnel.
- 1
Analysis of Strength Parameters of Coarse Sandstone Based on Particle Size DifferenceAbstract:
In order to explore the influence law and correlation degree of particle size difference on compressive strength, elastic modulus, Poisson " s ratio and crack evolution of coarse sandstone, based on laboratory tests, the particle flow numerical simulation software PFC3D was used to calibrate parameters to obtain reasonable mesoscopic parameters of rock mass. Different horizontal particle size ratio models were established and uniaxial compression simulation experiments were carried out. The variation law of parameters of coarse sandstone based on particle size difference was analyzed. The correlation between particle size ratio and mechanical parameters of coarse sandstone was quantitatively analyzed by grey correlation model. The results show that with the increase of particle size ratio from 2.0 to 5.0, the compressive strength of rock mass decreases by 29.93 %, the elastic modulus decreases by 17.20 %, and the Poisson " s ratio increases by 5.69 %. According to the crack evolution law, it is divided into the first interval 2.0 ≤ r≤3.0, the second interval 3.0 < r ≤4.0, and the third interval 4.0 < r<5.0. The number of tension and shear cracks is negatively correlated with the particle size ratio, and the change trend of shear cracks is the third interval
- 1
Experimental study on Optimization of blasting parameters based on SSA-BP neural networkAbstract:
In order to select blasting parameters quickly and reasonably in mines, a mathematical model of BP neural network optimized by sparrow search algorithm (SSA) is proposed. Six influencing factors of rock explosibility such as tensile strength, elastic modulus and friction angle are taken as input factors, and hole bottom distance, row distance and explosive consumption are taken as output factors Taking the actual parameters of a mine as an example, through the optimization, the blasting parameters row spacing is 1.2377 m, hole bottom spacing is 1.5 m, and the explosive consumption is 0.1603 kg/t. Practice shows that this model can effectively improve the traditional BP neural network convergence speed is slow, the accuracy is relatively low, and the optimized blasting parameters can achieve good blasting effect.
- 1
Instability Characteristics and Support Design of Surrounding Rock of Roadway Facing Mining in Near Distance Coal SeamAbstract:
Based on the research background of the instability characteristics and control of the surrounding rock of the dynamic pressure roadway in the process of mining the coal seam in the close distance of Xiangshan Coal Mine, the instability characteristics and support design of the surrounding rock of the roadway in the close distance coal seam are discussed by combining theoretical analysis, numerical simulation and engineering practice.The results show that the leading dynamic pressure of 12306 working face has a strong disturbance to the stope floor within 20 m, and the failure depth is 18 m, located 5 m behind the working face.The height of the ultimate equilibrium arch of the return air roadway at 12506 working face is 4.59m, which is within the damage range of the upper coal seam under the influence of advanced dynamic pressure.The control effects of the three support schemes are compared and analyzed by numerical simulation, and the optimal support scheme for surrounding rock of the return air roadway under the influence of advanced dynamic pressure is obtained.According to field monitoring, the final displacement of roof and floor is 511 mm and the displacement of two sides is 415 mm under the condition of roadway stopping and excavation dynamic pressure, which effectively controls the deformation of roadway surrounding rock and solves the problem of replacement tension in extremely close coal seam mining in Xiangshan Coal Mine.
- 1
Energy evolution and damage characteristics of saturated rock-like material under cyclic loading and unloadingAbstract:
In order to study the energy evolution and damage characteristics of saturated rock under cyclic loading, graded cyclic loading and unloading tests and equal amplitude cyclic loading and unloading tests were carried out with cement mortar materials. The strain characteristics, elastic modulus, energy density and damage variables of saturated rock under different cyclic loading and unloading methods were compared and analyzed. The results show that the initial cyclic residual plastic strain of saturated rock material is larger under the two cyclic loading and unloading, accounting for 61% and 76% of the total residual plastic strain respectively; Under graded cyclic loading and unloading, the elastic modulus first increases and then decreases with the increase of cyclic grade, the input energy density and elastic energy density increase with the increase of cyclic grade, the dissipative energy density first decreases and then increases, and the energy consumption ratio presents a "spoon" shape; Under the equal amplitude cyclic load, the elastic modulus keeps stable with the number of cycles, the three energy densities basically keep constant values in the damage stable development stage, and the energy consumption ratio increases rapidly in the material failure stage; The damage variable defined by the dissipated energy increases in a concave shape with the increase of cycle level; The cumulative total strain energy is 34.5 times of the hierarchical cyclic loading and unloading, the damage degree is more sufficient.
- 1
OPTIMIZATION OF PARTICLE SIZE DISTRIBUTION OF GRINDING PRODUCTS OF GOLD ORE FROM SHANDONGAbstract:
A Gold ore dressing plant in Shandong province, the ground working milling medium system only add 100mm steel ball, there existed high steel ball consumption, low quality grinding product, low recovery rate concentrate. With the analysis result of mechanical properties, ball mill ore feeding, ejection, particle classifier overflow and repetition, At the same time, a comparative test study of different steel ball medium schemes was carried out. Research and Discovering the ore has large variance of of mechanical properties, presence of high hardness doping brittleness condition belong to hard mineral grinding. Experiment determination recommended schemeΦ100: Φ80: Φ60: Φ40 = 15:20:30:35 was finally determined as the best steel ball medium ratio scheme to improve the ball mill's grinding operation quality. Compared with the plant scheme, the recommended scheme +0.28 mm grade yield is reduced by 8.22 percentage points. Yields of -0.074 mm have increased by 9.65 percentage points , and the efficiency of grinding technology has increased by 12.34 percentage points. Optimization of particle size distribution of grinding, the concentrate recovery rate has increased by 2.25 percentage points with significantly raised economic benefit.
- 1
Research on reliability of coal mine intelligent mechanization system based on Improved AHP fuzzy evaluation methodAbstract:
In order to systematically, quantitatively and objectively analyze and evaluate the reliability of intelligent mechanization system in coal mine, the improved AHP fuzzy evaluation model is established. According to the actual situation of Huacheng coal mine in Guizhou Province, the hierarchical structure model is established from four aspects of ventilation, gas drainage, transportation, drainage, air pressure and power supply and distribution. A total of 27 three-level indexes are established, The judgment matrix is established by using the three scale method of improved AHP, and the weight vector is obtained by calculation for fuzzy comprehensive evaluation. The results show that the comprehensive evaluation of the reliability of the intelligent mechanization system in Huacheng coal mine is 76.29, and the corresponding reliability level is relatively reliable, which is in line with the situation of the intelligent mechanization system in the coal mine.
- 1
Analysis and Research on overburden failure law of repeated mining in shallow and close seam groupAbstract:
Based on the research background of shallow buried close coal seam group in Hanjiawan coal mine in Northern Shaanxi Province, the paper analyzes and studies the failure law of overburden under repeated mining conditions of shallow buried close distance coal seam group through physical similarity simulation experiment and field measurement. The results show that the average step distance from the 2-2 coal seam cycle is 14.53m, the average step distance from the 3-1 coal seam cycle is 15.61m, the average pressure step distance from the 4-2 coal seam cycle is 16.50m, the coal seam adopts the downward mining, and the pressure step distance of the lower coal seam recovery cycle is greater than that of the previous coal seam. The height of simulated falling zone of 2-2 coal seam is 18m, the maximum height of fracture zone is 44m (developed to the lower part of load layer), the height of simulated falling zone of 3-1 coal seam is 11.5m, the maximum height of fracture zone is 80.5m, the height of simulated cross falling zone of 4-2 coal seam is 10m, the maximum height of fracture zone is 115.93m, and the overburden fracture of 3-1 coal and 4-2 coal seam is connected with the upper coal seam goaf. The results show that the data obtained from physical similarity simulation experiment are in accordance with the field data, and the feasibility of similar simulation experiment on similar problems is verified.
- 1
Analysis Of Influencing Factors Of Slope Instability In Western Open-pit MineAbstract:
Under the influence of underground mining, mine earthquake and other factors for many years in the West Open-pit mine, the slope often appears landslide phenomenon, and then causes a series of secondary disasters, such as ground fissures and wall cracks. Aiming at the instability phenomenon of open pit slope, the fault tree analysis method in safety system engineering is introduced. Through field survey and data investigation, the fault tree model of slope instability in West-Open pit mine is constructed. The results show that there are 132 minimum cut sets which can cause slope instability and 2 minimum diameter sets which can not cause slope instability, and the probability of slope instability is great. Among the 20 basic events, rainwater, cyclic freeze-thaw and the existence of weak intercalation are the key factors of slope instability. Combined with numerical analysis, it is found that the slope may be unstable along the upper and lower weak intercalation during the strength softening process of weak intercalation, and the slope stability is very sensitive to the internal friction angle of the upper weak intercalation. In the process of rainwater infiltration into the slope, the matric suction and volume moisture content of the slope surface increase continuously, which leads to the increase of surface bulk density. At the same time, the softening effect of water on the rock is not conducive to the stability of the slope. The relevant conclusions can provide a reference for the disaster management of open slope.
- 1
Research on Reasonable Supporting Parameters of GFRP Bolt under the Massive Backfill in Jinchuan No.2 MineAbstract:
Aiming at the reasonable supporting parameters of GFRP bolt under the massive backfill in Jinchuan No.2 mining area, five main parameters, including bolt length, bolt diameter, bolt spacing, bolt row spacing and shotcrete thickness, were selected based on the orthogonal experimental design method. The supporting effects under different parameter combinations were numericalized. Taking the roadway deformation, plastic zone volume and economic cost as evaluation indexes, range analysis method and matrix analysis method were used to analyze the influence of each parameter on the supporting effect. The results show that: the supporting effect is the best when the bolt length is 2.2 m, the bolt diameter is 20 mm, the bolt spacing is 1.2 m, the bolt row spacing is 0.8 m, and the shotcrete thickness is 100 mm. The influence order of each parameter on the supporting effect is the shotcrete thickness, the bolt row spacing, the bolt spacing, the bolt diameter and the bolt length. The research provides theoretical basis for the reasonable selection of the supporting parameters of GFRP bolt under the massive backfill in Jinchuan No.2 Mining Area.
- 1
MACRO AND MESOSCOPIC EXPERIMENTAL RESEARCH ON TRIAXIAL COMPRESSION CHARACTERISTICS OF FRACTURED COAL AND ROCK MASSAbstract:
This article relies on Shaanxi Coal Group Xiashijie Coal Mine to carry out research work. Taking the prefabricated fractured coal and rock mass as the research object, the macroscopic triaxial compression test and the microscopic nuclear magnetic resonance test are used to study the macro and microscopic deformation, failure characteristics and mechanical properties of the fractured coal rock mass under the triaxial compression test. Research indicates: (1) The triaxial compression strength of intact coal samples is the most sensitive to confining pressure, followed by coal samples with an inclination angle of 45°, and the smallest in an inclination angle of 60°. (2) The failure mode of fractured coal samples changes from direct shear failure to excessive oblique shear failure with the increase of confining pressure. As the confining pressure increases, the rupture angle increases significantly. As the inclination of the crack increases, the specimen is more broken, and the damage is mainly concentrated in the lower part of the coal and rock. (3) The total area of fractured coal and rock and the percentage of the total area of the fourth peak are positively correlated with the confining pressure and the inclination of the fracture. The pore size of fractured coal rock is mainly distributed in 1~10μm, and the proportion of large-pore pores is higher after failure. With the increase of fracture angle and confining pressure, the inside of fractured coal rock is more broken.
- 1
Influence of intermediate principal stress on triaxial unloading failure and energy characteristics of deep hard rockAbstract:
In order to analyze the influence of different intermediate principal stress rockburst, this paper adopts the method of single face and five faces to carry out true triaxial test on the rockburst process of deep granite specimens. The particle size distribution characteristics of explosive fragments and the energy evolution characteristics of rocks are studied. The test results show that as the intermediate principal stress increases, the time point for the first particle ejection phenomenon is delayed, and the duration of the rockburst process is correspondingly longer. In the range of intermediate principal stress of 10~40MPa, rock burst pits appear, which mostly show the "V" type characteristics. The size of rock burst pit and debris mass increase with the increase of intermediate principal stress, and the percentage of debris mass particles and fine particles increases, while the coarse particles decrease. It is found that in the process of rockburst test, the increase of intermediate principal stress makes the energy released in the process of rock burst before the peak value. When the total energy U, elastic strain energy Ue, dissipated energy Ud and dissipated energy ratio Ud/U are at the peak value, they increase with the increase of intermediate principal stress. The research results are of scientific value to further explore the rockburst mechanism of hard rock under a deep three-direction stress environment.
- 1
FACTORIAL ANALYSIS OF INFLUENCE OF THE DISCONTINUOUS ON MINE STABILITYAbstract:
In order to study the influence of the engineering characteristics of the underground mine rock mass and hydrogeological factors on the stability of the drift, the discrete element numerical simulation method was used to calculate the safety factor FSN under different levels of the characteristics and physical properties of discontinuities, the initial stress and the size of the drift. The safety factor FSN is compared with it of the complete rock FSI and the factorial analysis is carried out. The results show that among all the factors affecting the safety factor of the drift, the factors above the significant level are the size of the drift, the lateral pressure ratio and the characteristics of the discontinuity, namely the fracture size, the fracture aperture, and fracture intensity. The pore water pressure exerted by the discontinuous surface will affect the effective stress and shear strength of the discontinuous surface, resulting in an average reduction of the safety factor of 23%. Finally, the correctness of the theoretical research and the application method of the theory in engineering are verified in combination with the actual on-site.
- 1
Study on Influence of Diversified Replacement of Iron Tailings Sand on Compressive Strength of ConcreteAbstract:
In order to increase the content of iron tailing sand in concrete, four different alternative methods were selected to study the influence of the content of iron tailing sand on the compressive strength of concrete under different alternative methods. The test results show that the compressive strength of the iron tailing sand concrete prepared by different alternative methods is greater than that of the standard group concrete when the content is less than 30%. Using similar fineness modulus and other quality substitution, corresponding particle size and other quality substitution, equal quality substitution of river sand ≥1.18mm, and equal quality substitution of river sand <1.18mm, iron tailing fine aggregate concrete prepared by 4 alternative methods Compared with the standard group, the compressive strength of concrete increased by 13.5%, 10.2%, 16.9%, and 8.9%, respectively, and the corresponding optimal content percentages were 30%, 40%, 10%, and 20%. Under different alternative methods, the compressive strength of iron tailings concrete and the content of iron tailings sand vary in different trends, but the iron tailings concrete prepared with different content of iron tailings sand meets the requirements of C30 concrete strength grade.
- 1
Influence of sequential continuous mining in multiple mining areas on surface structuresAbstract:
In recent decades, the Laohutai mining area in Fushun has been repeatedly mined for many times. In order to ensure the safe mining of - 280 mining area in Laohutai mine, the possibility of water inrush accident occurred in the reservoir of nearly 100000 m3 above the mining area by continuous mining in time sequence between - 280 mining area and previous multiple mining areas was studied. The height of water flowing fracture zone was determined by numerical simulation combined with empirical formula, and analyzed, Draw the overlying rock failure area of continuous mining in different mining areas, on this basis, judge that with the coal seam mining will induce roof water inrush accident, move the reservoir to the west of the mining area, and consider the subsequent coal seam mining, set up protective coal pillar.
- 1
Affect on the synergistic separation of low-grade copper-molybdenum ore with aromatic hydrocarbons and phosphorus-containing compoundsAbstract:
Aiming at the problems of low-grade copper-molybdenum ore, such as fine embedded particle size, difficult separation of copper-molybdenum ore and metal loss, It is found that Synergy between the special high boiling point aromatic hydrocarbon and phosphide can greatly improve the concentrate of low-grade copper-molybdenum ore. Aromatic poly C=C bond can be adsorbed on molybdenite minerals in the pulp, the thioindene contained in high boiling point industrial aromatic hydrocarbon has excellent collecting ability for chalcopyrite, and the ammonium dimethyl dithiophosphate has the weak selective ability for pyrite and good selectivity for chalcopyrite in the process of copper-molybdenum flotation. The characteristics of a very large and low-grade-copper molybdenum ore in Inner Mongolia were determined by laser particle size analysis and XRD. Analysis of collector structure and adsorption characteristics on sulfide ore surface by GC-MS and IR techniques were conducted. The flotation of low-grade copper-molybdenum ore with copper-grade of 0.241% and molybdenum grade of 0.036 2% was carried out by one roughing, three cleanings and three scavengings. The recovery rate of copper increased from 88.35% to 91.57%, molybdenum grade 2.44%, and molybdenum recovery increased from 75.79% to 86.28% of the original process. The experimental results show that the synergistic of aromatic hydrocarbons and phosphates show a good selectivity in the flotation of copper-molybdenum ores in the presence of pyrite, which has theoretical significance and application value for the flotation of low-grade copper-molybdenum ore in the future.
- 1
Analysis of transport characteristics of filling slurry in multi-dip bend pipeAbstract:
For the study of coal gangue in filling pulp containing more syphon inclination of the transmission characteristics of gravity, in a certain coal mine filling line for background modeling, using the Fluent software to simulate the slurry in the pipe conveying process, analysis of different inlet velocity and concentration slurry in the containing multiple angle bending tube flow speed, pressure characteristics and the influence of the resistance loss. The results show that the velocity gradient at the outlet section of each elbow increases with the increase of the inlet velocity. When the inlet velocity is greater than 1.4m/s, the ladder difference increases greatly. When the slurry concentration is more than 78%, the growth rate of the resistance loss values along the pipeline and the local resistance loss values of each bend section is accelerated. The local resistance loss of each elbow section increases with the decrease of inclination angle. It is suggested that the inclination Angle of the elbow section should be greater than 60° when the slurry is filled.
- 1
Numerical Simulation Study of Complex Mine Fire Based on VentsimAbstract:
To study the smoke diffusion law of complex mine fire and the influence range of fire pressure, Ventsim was used to conduct fire simulation in a gold mine under three different working conditions (Fire simulation conditions 1 and 2 are located in the ramp, and fire simulation conditions 3 is located in the main intake airway), to study the change of wind pressure and smoke diffusion when the fire occurs. The results show that the influence degree of fire pressure decreases linearly with the increase of fire source distance. According to the simulated smoke diffusion time of each fire simulation condition, the mine needs to reverse ventilation within 700s and organize the staff to escape. In fire simulation conditions 3, the smoke diffusion speed is faster and the range is wider, that is, the fire risk of the main intake airway is greater. The ramp is the main diffusion path of smoke, should not be used as an escape path, in the event of a fire, staff should be organized to escape through the exhaust section. The research content has important guiding significance for the mine fire rescue.
- 1
Study on Gravity Conveying of Fine Tailings and Paste Considering the Influence of Slurry TemperatureAbstract:
Backfilling materials to explore slurry temperature under the influence of super fine paste big gravity flow characteristics, constructs the ultrafine backfilling paste gravity hydraulic gradient model, verify the authenticity and the rationality of the mathematical model, based on the numerical simulation analysis of the different flow, considering the influences of temperature of slurry filling times line of ultrafine backfilling paste gravity hydraulic gradient features.The results show that the measurement errors of the established hydraulic slope model are 4.85% and 2.21%, and the model converges after 56 and 68 iterations, indicating that the model is reliable and reasonable.With the increase of flow rate, the hydraulic slope of ultra-fine tailings paste increases, and the smaller the filling doubling line, the more linear the increasing trend.During paste transportation, there is a phenomenon of "non-uniform interference settlement" between coarse and fine particles. With the increase of filling doubling line, coarse particles are affected by fine particles and slurry solution instead of uniform settlement, resulting in an increase in the number of particle interactions and an increase in hydraulic slope.There is a certain law of paste coarse particle migration, and the yield stress is the most critical factor affecting the particle migration.Based on the test results, it is recommended to select 220m3·h-1 as the conveying flow and 5 as the filling doubling line for the realization of autolitization.
- 1
Experimental study on improving gold recovery rate of Hatu mud bearing refractory gold mineAbstract:
The Western Gold Hatu Gold Mine is a low-sulfur arsenic gold ore supplemented by natural gold and supplemented by sulfide-coated gold; there are a large number of calcium, magnesium, aluminum silicates and carbonates in the ore that are easy to float and easy mud Chemical alteration of minerals, resulting in high Production site production run-off and significant fluctuations in indicators. Through detailed process mineralogy research, the application of the high-efficiency argillaceous gangue inhibitor XJ-11 independently developed, combined with the collaborative optimization of the applicable pharmaceutical system based on argillaceous inhibitors, the closed circuit test of the laboratory obtained Gold concentrate with Au grade of 94.50g/t, recovery rate of 93.16%, Production site verification of the closed-circuit test run stably fell below 0.25g/t, and the recovery rate of flotation operations was relatively increased by 2.5%～5%, which achieved satisfactory technical indicators.
- 1
Mechanical Model and Stability Analysis of Filling Body Roof in Downward Approach StopeAbstract:
In mines where the downward filling mining method is applied, the stoping work is carried out directly under the roof of the filling body. It is of great significance to study the safety and stability of the top plate of the filling body. Taking Gansu mine as the industrial background, based on the thin plate model and catastrophe theory, the mechanical model of the stope filling body roof is constructed, the critical conditions for the sudden instability of the filling body roof are analyzed. The safe thickness is calculated by inverse calculation, and the maximum filling body thickness that the mine can currently bear is obtained. The research conclusions show that the core factor affecting the stability of the roof of the filling body is the thickness of the roof, and the existing stope structure parameters can meet the safety requirements of the roof thickness for continuous downward filling and mining of the ore body. It provides new ideas for exploring the stability of the stope filling body roof.
- 1
Study on stability analysis and control technology of surrounding rock in the final mining of withdrawal channelAbstract:
Aiming at the problem of the severe impact of the withdrawal channel during the final mining period, through on-site monitoring and numerical simulation, the regional stress evolution law and surrounding rock plastic failure characteristics of the 3101 working face in Talahao Coal Mine were studied. The results show that: (1 ) During the final mining period, the influence of the working face within 20m of the advance retracement channel is severe, and the surrounding rock is seriously unstable; (2) During the period from 20m to the penetration of the working face from the main retracement, the stress distribution in the main retracement channel changes from "asymmetric double The “peak” state gradually strengthened and finally evolved into a “symmetrical unimodal” state. The value of the stress field in the auxiliary retracement channel area increased, and the state remained basically unchanged; (3) During the final mining period, the plastic zone of the main retracement channel surrounding rock gradually expanded, and the auxiliary retracement The plastic zone of the surrounding rock of the passage does not change significantly. Based on this, adhere to the principle of top-side collaborative control, and propose a preventive support and reinforcement plan to coordinate the surrounding rock stability control measures during the final mining period, and the field application effect is good.
- 1
Research on the Law of Surface Movement in Mining of Orebody under Filling StationAbstract:
Surface movement caused by underground mining is an important factor in surface stability. In order to ensure the safety of the filling station during the mining of a large iron mine in Shandong, four different sizes of security pillar schemes below the filling station were designed. Referring to the specifications of coal mining and pillar retention under buildings, water, railways, three-dimensional modeling software and finite difference method software were used for simulation calculation, the security pillar size was optimized.It is concluded that the size of the security pillar of the filling station is not less than 50×85m, the research not only guaranteed mine production safety, but also improved mine resource recovery rate and economic benefits.
- 1
Effect of different air entraining agents on mechanical properties of filling slurry and filling bodyAbstract:
In order to explore the effects of different types of air-entraining agents on the mechanical properties of filler slurry and filling bodies, a new type of full tailings filler was prepared with 425# ordinary Portland cement, all tailings of a mine, city tap water and three types of air-entraining agents Condensable materials, explore the rheological properties of the filler slurry and the early strength characteristics of the filler under different air-entraining agents, and use SEM to explore the pore structure characteristics of the filler under different types of air-entraining agents. The results show that the plastic viscosity and yield stress of the slurry decrease under the action of the k12 air-entraining agent, which is beneficial to the fluidity of the slurry; the addition of the air-entraining agent reduces the early strength of the filling body, and the decrease of k12 is the smallest; the SEM microstructure shows that the air-entraining agent is introduced The bubbles cause more pore structure inside the filling body. This kind of bubbles is the main reason for the decrease in the strength of the filling body. The smaller the bubbles, the more uniform the strength decreases. Comprehensively consider the relationship between the rheological properties of the slurry and the 7d compressive strength, combined with the microscopic investigation of the filling body, aiming at the three mainstream air-entraining agents on the market, under the conditions of a slurry mass concentration of 60% and a lime-sand ratio of 1:4 , K12 is more effective as an air-entraining agent in the filling process.
- 1
Study on the Effect of Surface Pickling on the Classified Flotation of Low-rank CoalAbstract:
Low-rank coal with a large resource reserve exists in China. However, due to its rich surface oxygen-containing functional groups, developed pores and large surface roughness, the low-rank coal flotation process has not been industrially applied. In order to improve the floatability of low-rank coal particles, the pickling treatment with hydrochloric acid was carried out on the size fractions of 0.500-0.250 mm, 0.250-0.125 mm, 0.125-0.074 mm and -0.074 mm with lower ash content. The flotation results after pickling treatment showed that the flotation concentrate yields of 0.500-0.250 mm, 0.250-0.125 mm and 0.125-0.074 mm size fractions reached the maximum 97.87%, 98.95% and 97.22%, respectively, at 2 mol/L pickling concentration; then as the pickling concentration continued to increase, the flotation concentrate yields decreased to a minimum of 93.51%, 90.70% and 89.43%, respectively. However, the flotation recovery concentrate of -0.074 mm size fraction was continuously reduced from 94.10% to 48.18% with the pickling concentration increasement. Dependent on the Zeta potential tests and scanning electron microscopy (SEM) analysis results, it can be found that a lower pickling concentration (2 mol/L) can effectively remove the oxygen-containing functional groups with strong negative charge, thereby improving the floatability of the low-rank coal surface, while the surface pores of low-rank coal increased significantly with the higher pickling concentration (4 mol/L~10 mol/L). During the flotation process, the newly added pores will be filled with water molecules and form a hydration film, thereby reducing the hydrophobicity of the low-rank coal surfaces. Thus, the flotation concentrate yield of low-rank coal decreased at higher pickling concentration.
- 1
Stability analysis method of dangerous rock mass based on amplitude ratioAbstract:
The bonding area of joint surface controls the stability of rock mass, and also affects the dynamic response of rock. By analyzing the relationship between the bonding area of joint surface and the stiffness of joint surface, the relationship between the ratio of vibration amplitude of rock mass and bedrock and the bonding area of joint surface can be established. Combined with the limit equilibrium theory, the calculation method of unstable rock mass stability based on amplitude ratio index can be established. The concept of resonant bond length is proposed : when the bond length of rock joint surface reaches resonant bond length, the vibration response of dangerous rock mass to bedrock is the largest. On both sides of resonant bond length, the amplitude ratio of rock mass will change oppositely with the change of bond length. Through the numerical simulation of typical dangerous rock mass, the difference between the simulation results of rock mass amplitude ratio and the theoretical results is analyzed, which confirms the effectiveness of the rock mass stability analysis method based on amplitude ratio.
- 1
Optimization model of ore blending of limestone open-pit mine based on interactive fuzzy multi-objectiveAbstract:
Aiming at the actual ore blending demand of limestone open-pit mine, an ore blending model based on fuzzy multi-objective was established. The model firstly considers two objectives of ore blending, namely grade deviation and production energy consumption of limestone open-pit mine. At the same time, the concept of fuzziness is introduced to carry out fuzzy processing for multiple objectives with low correlation. Based on the maximum and minimum theory, the established multi-objective problem is transformed into a single objective problem. Secondly, in the aspect of solving algorithm, the specific coding method and the adaptive adjustment of crossover mutation operator are adopted, and the optimization genetic algorithm is used to solve the established model. Finally, the simulation experiment is carried out with the data of a large limestone open-pit mine in China as an example. The experimental results verify the effectiveness and economy of the model, which can reduce the deviation of ore grade and achieve the purpose of reducing cost and increasing efficiency of mining enterprises.
- 1
Experimental Research on the Defogging Efficiency of a Lead-Zinc Mine HeadAbstract:
In winter, the underground mine return air shaft produces fog to varying degrees. As the fog continues to diffuse, it affects the living environment of the surrounding residential areas, causing an uneasy psychological effect, causing the return air shaft to not be used normally, and affecting the entire return air system of the mine. Cause a serious impact. Relying on the ventilation optimization project of a mine in Yunnan as a background, on site testing, the difference in air moisture content and the amount of fogging water released under different working conditions were obtained, and a defogging geometric model was established based on some similar principles. The model scale was 1:10 , Through the experiment and comparison of the defogging efficiency under different working conditions. It is concluded that the cooling effect is about 1.2 ℃, the pressure drop is less than or equal to 189 Pa, and the wind speed reaches 4.5 m/s, the best defogging efficiency is 96.3%, which provides certain theoretical guidance for the application of mine pit defogging.
- 1
Study on mechanical properties and optimization design of proportioning parameters of cemented backfill with coarse aggregateAbstract:
Orthogonal test design was carried out to study the effects of mass concentration, cement-sand ratio, coarse aggregate content and water reducer content on the mechanical properties of cemented backfill with mixed aggregate. Through range analysis and variance analysis of compressive strength and slump of backfill, the influence degree and significant influence factors of the four factors were obtained. The results show that the mass concentration, the content of coarse aggregate and the dosage of water reducer are the significant factors affecting the slump of filling slurry, while the dosage of cement has no significant effect on the slump of filling slurry. The content and mass concentration of coarse aggregate are the significant influencing factors for the early strength of backfill, while the mass concentration and cement content are the significant influencing factors for the middle and late strength of backfill. The compressive strength of backfill increases first and then decreases with the increase of coarse aggregate content, and the optimal coarse aggregate content is 60%. Finally, the influence of the four factors on the mechanical properties of the cemented backfill of mixed aggregate was analyzed, and the regression model of the slump and compressive strength of the coarse aggregate backfill was established. The model can accurately predict the change rule of the slump and compressive strength of the coarse aggregate backfill. In addition, combining with the experimental results, it is known that the best strength compound admixture combination of the metal mine filling body is A1B2C3D4.
- 1
Effect of redox potential on the migration and transformation of uranium at the water-rock interfaceAbstract:
In this paper, the uranium ore samples were taken from the decommissioned area in the in situ leach mine in Nothwest China, the sandstone uranium ore columns with different redox potentials were prepared, simulation tests of the infiltration of uranium solution through them were conducted, the concentrations of uranium and iron, redox potential (Eh), pH and electrical conductivity (EC) of the effluents from the columns were measured, the contents and uranium species at different depths of the columns after the tests were analyzed, and the samples before and after the tests were characterized by SEM and FT-IR. The results show that the migration rate of uranium in the uranium ore under oxidation conditions > the migration rate of uranium in the uranium ore under original conditions > the migration rate of uranium in the uranium ore under reduction conditions, that the species of uranium is mainly in the residual and carbonate bound states under original conditions and reduction conditions, the residual fractions are 48% ~ 58% and 30% ~ 49%, respectively, and the carbonate bound fractions are 27% ~ 49% and 30% ~ 49%, respectively, and that the species of uranium is mainly in the residual state, carbonate bound state and exchangeable state under oxidation conditions, and their percentages are 50% ~ 60%, 19% ~ 27% and 10% ~ 15%, respectively.
- 1
Evolution characteristics of magnetite multistage crushing based on fractal theoryAbstract:
To research multistage crushing evolution characteristics of magnetite, a physical experimental model of magnetite multistage crushing is established based on the fractal theory of rock fragmentation. Multistage crushing tests on irregular magnetite were carried out with drop weight impact apparatus to simulate the general process of magnetite crushing from initial size to target size. So the inversion of the mechanical crushing process of ore was realized with laboratory test, and the gradual evolution regulations of grain size and fragments distribution characteristics were revealed. The research shows that the particle size distribution curve, average particle size, median particle size and fractal dimension can completely describe the evolution characteristics of magnetite multistage crushing. With the increasing in crushing steps, the particle size distribution tends to be uniform, and the degree of gradation change gradually decreases, and the average particle size and median particle size of the fragments decrease as well whose decreasing range gradually decreases, and the change gradient of average particle size is more significant. The particle size distribution after each crushing stage has fractal characteristics. The multistage crushing process has self-similarity. After each crushing stage, the fractal dimension of fragment size increases to be a stable value with the gradually decreasing in its increasing rate. A method is proposed to simulate the evolution process of ore mechanical crushing by means of multistage crushing with drop weight impact in this paper. It is the first time to verify that the mechanical crushing process of ore accords with the fractal theory of ore crushing from the aspects of physical tests. The research results provide theoretical basis for particle size control druing mechanical crushing and ore crushing process improvement.
- 1
Correlation analysis of the hazards of tailings pond failure based on text miningAbstract:
As a human-made high potential energy debris flow, in the case of the tailings pond failure, it may cause severe loss of life, ecological environment and even threaten social harmony and stability. According to the internaitonal accidents statistic, the tailings pond failure ranks the 18th. In the paper, firstly, many tailings pond failure cases both at domestic and abroad are collected and analyzed. The hazards leading to the failure are cut and digged by the text mining. The word cloud diagram of hazards are drawed using the Python. Secondly, on the basis of the word frequency, the Apriori algorithm is used to demonstrate and chatacterize the relationship among the hazards. Finally, the co-occurrence matrix is acquired and transformed into co-occurrence network by the Ucinet, Gephi and other software. The visualization of relationship among the hazards is realized. The results are of big reference to prevent the talings pond failure and improve the safety management of the tailings pond.
- 1
Experimental study on influence factors of permeability of different coal-rock combinationAbstract:
In order to study the permeability of different coal-rock assemblages, the permeability tests were carried out under different conditions for different combinations of block coal, sandstone and mudstone in Yushe-Wuxiang County area of Qinshui Basin, Shanxi Province. The results show that: 1) under the constant pore pressure, with the increase of the effective stress, the permeability decreases rapidly and then slowly, and the permeability increases gradually when the effective stress increases to the extent that the coal and rock are broken, and the trend accords with the quadratic function; 2) under the constant triaxial stress, the permeability decreases with the increase of the pore pressure in a quadratic function curve, and then increases with the decrease of the permeability first, and then decreases slowly; 2 MPA is the "critical pressure" in the experiment; 3) when other conditions remain unchanged, the water cut increases and the permeability decreases with the negative exponential function. When the pore pressure is constant, the higher the triaxial stress is, the greater the influence of the water cut on the permeability of coal and rock is; when the triaxial stress is constant, the higher the pore pressure is, the greater the influence of the water cut on the permeability of coal and rock is;. The research results provide theoretical basis and experimental support for efficient exploitation of coal-bearing gas resources in the Qinshui Basin.
- 1
APPLICATION STATUS OF 3D LASER SCANNING TECHNOLOGY IN DOMESTIC MINE FIELDAbstract:
The application status of 3D laser scanning technology in five fields (mined-out area, slope, blasting, mining subsidence and mine reserve) was reviewed. Additionally, the problems and trend in the above-mentioned fields were summarized. In general, the point cloud utilization will be high quality, maximum coverage, and the post-processing of point cloud data will be high precision. Moreover, the combination of new measurement technology, artificial intelligence algorithm and 3D laser scanning technology, and the development of data processing software and mine data management platform are important to realize the intelligent mine.
- 1
Selective flocculation and flotation of ultrafine cassiteriteAbstract:
In view of the characteristics of low grade cassiterite, high degree of argillization, many kinds of minerals, fine distribution with gangue minerals and high content of calcite carbonate minerals in a fine-grained (- 0.074mm) tin tailings in Nandan, the process of selective flocculation flotation cassiterite was used to study the fine-grained cassiterite, and the efficient recovery of cassiterite was realized. The results showed that under the condition of pH value of 6.5, the combined regulator sodium carboxymethyl cellulose (CMC)+sodium silicate, selective flocculant sulfonated polyacrylamide (PAMs), combined collector salicylhydroxamic acid + hydroxamic acid + p86 were used for selective flocculation recovery of cassiterite with tailings grade of 0.53%. Finally, the tin concentrate with grade of 9.35% and recovery rate of 81.80% was obtained, The enrichment ratio is 17.64.
- 1
Study on Rheological Characteristic of High-Aeolian-Sand Filling MaterialsAbstract:
RST-SST soft solid rheometer was used to study the rheological model of high-aeolian-sand filling materials through the control variable method, and the influence laws of fly ash content, cement-sand ratio and mass concentration on the rheological parameters of high-aeolian-sand filling materials were revealed.The results show that the high-aeolian-sand filling materials belongs to the Binghan model and has obvious characteristic of shear thinning. Fly ash content, cement-sand ratio and mass concentration all have significant influence on the rheological characteristic of high-aeolian-sand filling materials, but the rheological model does not change. With the increase of cement-sand ratio and mass concentration, the yield stress tends to increase, and the increase of fly ash content will lead to the decrease of yield stress. When cement: fly ash is 1:2, cement to sand ratio is 1:12 and the mass concentration is between 79.5%～80.5%, high-aeolian-sand filling materials has low plastic viscosity coefficient and good rheological characteristic.
- 1
Study on quantitative evaluation method of scientific mining of coal resourcesAbstract:
To develop scientific mining in coal mines, it is necessary to carry out quantitative evaluation on the level of scientific mining and get the evaluation results, so as to provide theoretical support for the improvement of relevant enterprises and departments in the next step. On the basis of fully studying the core connotation and main extension of scientific mining, the evaluation index system composed of 6 first-level indicators, 33 second-level indicators and 170 third-level indicators is constructed by selecting indicators. The standardized measurement method and sensitive index switching measurement method are used. Four methods of piecewise function measurement method and expert scoring method were used to quantify the indexes, and the subjective dynamic weighting method with multi-experts participation was adopted to give weight to the indexes. Based on the actual situation of a mine, using the above quantitative evaluation method, the scientific mining index and scientific mining level grade of the mine are obtained, and the next development suggestions are given.
- 1
Influence of Nitrogen Injection in Goaf on Coal Spontaneous Combustion Oxidation Zone under the Condition of High-Drainage Roadway ExtractionAbstract:
In order to study the distribution of the coal spontaneous combustion oxidation zone in the goaf under the combination of high-drainage roadway extraction and different nitrogen injection conditions, the width of the spontaneous combustion oxidation zone in the goaf on the inlet and return air side and the distribution of the distance from the working face were studied by setting six nitrogen injection locations and four nitrogen injection volumes. The results show that the setting of high-drainage roadway can promote the coal spontaneous combustion oxidation zone to move to the inside of the goaf, and the width of the oxidation zone will increases; the position five is the best nitrogen injection location. At this time, the width of the oxidation zone on the inlet side is the narrowest and the distance from the working face is also the farthest, and the width of the oxidation zone on the return air side is narrow and the distance from the working face is relatively long; the best nitrogen injection volume is 360 m3/h, and the change of the nitrogen injection volume has a greater impact on the inlet side of the goaf than on the return air side , the impact on the width of the oxidation zone is greater than the impact on the distance from the working face.
- 1
Flotation test of silver recovery from a zinc hydrometallurgical leaching residueAbstract:
The silver grade of a zinc hydrometallurgical leaching slag is 20 g/t, which lacks effective comprehensive recycling. Through MLA and silver phase analysis, it is found that its mineral composition is mainly composed of sulfide minerals such as pyrite, and it has the characteristics of low dissociation degree of mineral monomer and complex silver phase distribution. Combining the mineral properties of the leaching slag, the flotation test is carried out by the process of enhanced grinding and oxidation flotation. The test results show that with lime and water glass as inhibitors and sodium oleate as collectors, the process of one roughing and one sweeping flotation process can obtain silver grade and silver recovery of 54.00 g/t and 48.80%, respectively Of silver concentrate.
- 1
Study on Preparation of Sulphoaluminate Cement-based Flexible Mould Pumping Material Passing Through Mine Abandoned RoadwayAbstract:
Based on the characteristics of sulphoaluminate cement-based materials such as rapid coagulation and high solid-to-water ratio, this paper develops a single-liquid pumping material suitable for supporting flexible bag pillars in empty roadways. Through experimental research on the strength of raw materials with different proportions, the optimal components are 50% sulphoaluminate cement clinker, 41.7% gypsum and 8.3% lime. The influence law of retarder and water reducing agent on the fluidity of the material was studied separately, and the influence law of the strength of the two composite accelerators added to the material at each age was separately studied, and the optimal dosage range was obtained. The orthogonal test method is used to explore the influence of different admixtures on the fluidity and strength of the material. The analysis shows that the best ratio is 0.2% of retarder, 0.3% of water reducing agent, 0.1% of accelerator ①, and 1% of accelerator ②. Under this dosage, the fluidity of the material reaches 300mm at 23 min, and the strength of 4h, 3d, and 14d reach 7MPa, 12.4MPa, and 18.5MPa respectively, which meets the requirements of empty road construction and support.
- 1
Study on rheological properties of sand filling slurry with copper slag tailingsAbstract:
In order to analyze the rheological properties and yield stress influencing factors of copper-doped tailings filling slurry,, first by physical and chemical test copper backfilling materials selected and the chemical composition of waste rock and grading, and using the orthogonal experiment method, to carry out the different copper choose backfilling, mass concentration and dosage of gelled material adding amount of filling slurry rheological test, to get each slurry rheological curve. Finally, the experimental results were analyzed by combining the theories of grading, rheology, variance analysis, multivariate nonlinearity and curve estimation. The results showed that :(1) Copper tailings and waste rock meet the industrial application standards of backfilling aggregate; (2) The rheological model of copper-doped tailings slurry with high concentration filling is H-B model; (3) Slurry mass fraction is a significant factor affecting yield stress; (4) The multivariate nonlinear model established based on curve estimation has high accuracy and can predict the slurry yield stress, which provides a theoretical basis for the design of filling system.
- 1
A radial unstable gas flow model based on real gas and its analytical solutionAbstract:
A mathematical model of gas flow is established based on the Darcy"s law, the law of conservation of mass, and the real gas state equation. Using the separation variable method, the analytical solution of the gas pressure distribution law in the radially unstable flow field is obtained. The analytical solution obtained by using a different time and the pressure of gas drainage from the evolution of the distribution. Based on this, a theoretical method for calculating the extraction radius is proposed and verified by numerical simulation using COMSOL Multiphysics. The research results show that: according to the radial distribution of gas pressure, the surrounding area of the drainage borehole is divided into pressure-reducing zone, turning zone, and stable zone, and the difficulty of drainage increases in sequence. The gas pressure changes with time and space is mainly determined by the pressure criterion r^2/4ψt. The smaller the pressure criterion, the greater the gas pressure drop and the better the drainage effect. Narrowing the drainage interval r or extending the drainage time t can reduce the pressure criterion. Since it is the square of the drainage distance, relative to the drainage time, the gas pressure is more sensitive to the drainage distance. When the pressure criterion is greater than 4, the coal gas pressure is hardly affected by drainage.
- 1
EXPERIMENTAL RESEARCH ON FLOTATION AND GRAVITY SEPARATION OF A GOLD OREAbstract:
A new ore vein was discovered by prospecting in a certain area of Liaoning, with a gold grade of 2.87g/t. In order to improve the leaching ore grade and recovery rate of the gold mine, the grinding fineness, the reagent system test, the whole process open circuit and closed circuit test, etc. were explored to determine the appropriate beneficiation process, process parameters and process indicators. The results showed that: using a single flotation process: the technical indicators of the concentrate gold grade of 28.60g/t and the concentrate gold recovery rate of 93.47% were obtained. Using the combined process of gravity separation and flotation: heavy fine gold grade is 99.11g/t, heavy fine gold recovery rate is 44.10%, flotation concentrate gold grade is 17.97g/t, flotation concentrate gold recovery rate is 50.61%, fine gold the total recovery rate of the mine is 94.71%. Provide technical basis for rational development and utilization of resources.
- 1
Mechanism and experimental study of vibration dehydration based on bulk dynamicsAbstract:
The dehydration efficiency is one of the key factors affecting the stability of the whole tailings non-cemented backfill. Based on the theory of loose body dynamics, the dewatering mechanism of the whole tailings unconsolidated backfill was analyzed, and the variation of the dewatering efficiency of the whole tailings unconsolidated backfill under different vibration dewatering modes was studied. The test results show that: under the influence of vibration stress wave, the whole tailings loose body skeleton generates vertical stress and shear stress, among which the shear stress is the key to destroy the original structure of the loose body. The total dewatering amount of the whole process vibration increased by 27%, the dewatering time decreased by 83%, but the amount of tailings was large. Intermittent vibration cumulative water increased by 18%, dehydration time reduced by 50%, of backfilling loss is bigger, but compared with the intermittent vibration of the whole process of vibration of backfilling loss was reduced 50%, visible intermittent vibration is the best way when the vibration dehydration, not only can improve the efficiency of dehydration, at the same time also can reduce the loss of backfilling, guarantee the dehydration effect.
- 1
Application of upward horizontal layered filling mining method in steeply inclined broken thin orebodyAbstract:
Chaihulanzi Gold Mining Co., Ltd. 4# well V vein rock has poor stability. When resource recovery is carried out according to the previous mining method of the mine, there are problems of construction operation danger and high ore loss rate. Based on this, this paper has carried out a systematic study on the mining plan of the thin vein orebody of Chaikuang 4# well V. After the research status at home and abroad, the comparison of the mining plan and other technical means, the final determination of the up-direction level of the single mining unit outside the vein is determined. The layer-filling mining method is the best mining plan for this type of ore body. The on-site industrial test showed that the main technical and economic indicators of the single mining combined upward horizontal stratified filling mining method outside the vein can reach the expected target. The ore loss rate is 5.5%, the ore dilution rate is 6.5%, and the stope production capacity is 85t/d. It can effectively ensure the safety, high efficiency, and economic production of the stope, can be comprehensively promoted in the whole mine, and has important reference significance for the mining of similar mines.
- 1
Application of Control Blasting Method of Upper Approach Stoping in Shanjin of Song CountyAbstract:
The controlled blasting method of underground mining is an important part of ore mining. The traditional controlled blasting method is adopted in Songxianshan Jinyuan, which has some problems such as hard to extract the rock, hard to protect the filling body and hard to accurately control the blasting time of the hole. The above problems were studied, and the upward-facing stoping controlled blasting method was proposed. Firstly, a small wedge hole with a small inclination Angle was used to replace the common vertical hole, which could form a larger free space. Secondly, according to the theoretical calculation, the distance between the bottom eye and the lower filling body can be obtained to protect the lower filling body. Finally, the electronic detonator and detonating cord are used to replace the conventional detonating tube detonator, which can accurately control the detonating time and sequence of the hole. The method is applied to the controlled blasting experiment of Songxian Shanjin underground. The results show that the tunnel is 1.25% wide and 3.3% high, and the section regularity is improved to some extent. The average footage of roadway is 2.13m, and the blasting footage is greatly improved. The ore bulk rate is reduced and the overall blasting effect is good.
- 1
Ecological Risk Assessment of Typical Mining Areas in Daye City Based on RRM ModelAbstract:
The development of mineral resources disturbs the ecological environment of mining areas, exacerbates the risks of the ecological environment, and seriously hinders the sustainable development of the region. Aiming at the hidden ecological environmental dangers caused by the development of mineral resources, This article takes mining, beneficiation, smelting and mining activities as risk sources, determines point, line and surface stress factors from the perspective of production process links, analyzes the interaction between risk sources, habitats, and ecological receptors. Also, this article establishes the mining area ecological risk exposure response model and obtains a mining area ecological risk assessment method based on the relative risk model (RRM). The empirical study of typical mining areas in Daye City shows that the ecological risk assessment of mining areas based on RRM can comprehensively reflect the process and results of mining and metallurgical activities on the ecological environment from three aspects: ecological risk level, stress state, and ecological loss, and scientifically characterize the complexity of ecological risks in mining areas, and the evaluation results better reflect the actual situation of the study area. It has certain guiding significance for ecological risk management and control in mining areas.
- 1
Mine value chain modeling and ore cost analysis based on Petri netAbstract:
To achieve phased assessment of the ore value and fine evaluation of the cost, the system architecture of gold mine enterprise value chain is established based on the value chain theory from three dimensions of value-added activities, value subject and value carrier. Afterwards, value chain model taking ore flow as carrying body is built based on the Petri net. With the CPN Tools emulation tool, the model is simulated by the colored Petri net which contains the hierarchical structure. Taking a large-scale gold mining enterprise as an example, the value chain model is quantified in order to simulate the ore value formation, flow, transmission and implementation process. By analyzing the results of the simulation, ore value of different production stages is evaluated dynamically and the cost is analyzed in stages similarly, which can improve the mining enterprise cost management, evaluate the economic feasibility of ore utilization more accurately, and provide the basis for the value evaluation and effective utilization of low-grade ores.
- 1
Influence of rotating magnetic field on separation effect of dense medium cycloneAbstract:
The coaxial rotating magnetic field is applied at the cylinder position of the dense medium cyclone, and the movement of the dense medium powder is changed by the rotating magnetic field, so as to realize the on-line control of the separation density of the dense medium cyclone. The movement of steel ball and magnetite powder in different magnetic field was observed by using high-speed camera system. The suspension of magnetite powder was stirred and the liquid level change under the action of rotating magnetic field was observed.Based on the above research and observation, the coarse slime separation test was carried out. The results show that when the rotating magnetic field rotates clockwise and the steel ball rotates counterclockwise, the magnetite powder forms a magnetic chain and reverses anticlockwise.When the rotation speed of the magnetic field is large enough, the magnetic chain is connected end to end to form a magnetic ring, showing a ring shape. With the increase of magnetic field speed, the rotation speed of magnetite powder suspension first increases and then decreases. The cyclone separation test shows that the static magnetic field will destroy the separation effect of the cyclone, and the rotating magnetic field in the same direction with the feeding direction reduces the separation density of coarse particles, but increases the ash content of-0.25 mm fine particles. The rotating magnetic field in different directions reduces the separation density of the cyclone and improves the separation accuracy.
- 1
Investigation on defoaming of collophane flotation foamAbstract:
The amount of three-phase foam that occurs during the flotation process of collophane is large and it is not easy to dissipate. To solve this problem, this paper analyzes the factors that affect the stability of flotation foam. The defoaming test of three-phase foam was carried out by mechanical stirring and adding defoaming agent. It is found that dodecyl amine can obviously reduce the surface tension of the solution system，and fine hydrophobic mineral particles can enhance the stability of flotation foam. The faster the mechanical stirring speed is，the better the defoaming effect is. Different impeller types also have a great influence on the defoaming effect. The froth regulators tributyl phosphate，GPE polyether defoaming agent and organic silicon defoamer have good defoaming effect on dodecyl amine two-phase foam，but the defoaming effect is not good in three-phase foam because the defoaming agent can''t fully diffuse on the liquid film by its own adsorption. Combine defoaming with mechanical stirring and adding defoamer to achieve the best defoaming effect at low speed. The defoaming effect of mixing defoamers is better than using defoamers alone.
- 1
Development and application of hydro-mechanical-thermal coupling function in simulating crack propagation of FRACODAbstract:
In order to study the evolution mechanism of crack propagation in deep engineering rock masses under the coupling action of three fields of hydraulic-thermal-mechanical, based on the existing superior software FRACOD for crack propagation simulation, the hydraulic-thermal-mechanical (H-T-M) coupling module was further developed.This module uses the indirect boundary element-discontinuous displacement method for mechanical numerical calculations (rock mass deformation and crack growth) and transient heat flow simulation, and iterative method is used to simulate the crack growth process.And through the geothermal energy development, underground natural gas liquefaction storage engineering case analysis and verification.The results show that: (1) When the temperature of the injected fluid is different from the temperature of the surrounding rock, the fluid flowing in the fissures causes heat exchange to redistribute the temperature in the rock and the fluid, resulting in temperature pressure inside the rock mass, resulting in changes in the internal structure and promoting The crack propagation. (2) The influence of ice expansion on rock stress increases with the increase of the crack aperture. The resulting compressive stress closes the cracks in the rock mass and reduces the risk of fluid leakage. The experimental results obtained can clearly reflect the cracks, discontinuities and their propagation process and evolution laws, verifying the feasibility and superiority of the module.
- 1
A method of gas concentration prediction model based on PSO-CNN-aBiGRUAbstract:
Accurately Predicting the gas concentration of working face can effectively prevent coal mine gas disasters. Most of the commonly used gas concentration prediction methods only consider the temporal characteristics of gas monitoring data, and do not effectively utilize the spatial characteristics of gas data. Therefore, on the basis of effectively extracting the spatio-temporal characteristics of gas monitoring data, a gas concentration prediction method (PSO-CNN-aBiGRU) based on the optimized Convolutional Neural Network and the optimized Bidirectional Gated Unit Neural Network is proposed. Firstly, we apply the random forest and Hilbert-Huang Transform methods to process the missing and noise values in the gas monitoring data; then we use the Convolutional Neural Network (CNN) with Particle Swarm Optimization (PSO) to extract the spatial features from the processed gas. Finally, considering the historical information and future state of the data, the PSO-CNN-aBiGRU gas Concentration prediction model was constructed based on the adaptive Moment Estimation Max (Adamax) optimized bi-directional gated unit (Bi-directional Gated Recurrent Unit, BiGRU) neural network , and the Mean Square Error was used as an evaluating indicator to assess the prediction accuracy of the model. The experimental results show that compare to the PSO-CNN-BP, PSO-CNN-RNN and PSO-CNN-LSTM models, the PSO-CNN-aBiGRU reduces the error by 52.21%, 42.43% and 29.6% on the test set, respectively. Therefore, the PSO-CNN-aBiGRU model can effectively improve the accuracy of the gas concentration prediction, which is of practical significance for reducing gas disasters and ensure the safe production of coal mines.
- 1
Experimental Research and Calculation on Cutting Parameters of the Cobalt-rich Crust based on Helical Cutting TechnologyAbstract:
The cutting and crushing method suitable for the cobalt-rich crust ore body was put forward by studying of the characteristics of cobalt-rich crust substrate, and calculation model of cutting and crushing technical parameters of cobalt-rich crust was built and the empirical calculation formulas of cutting force and power are obtained by equivalent conversion method based the cutting empirical formula of grey cast iron. The simulated substrate and topography of cobalt-rich crusts were developed and laboratory experiments of simulated crusts cutting were carried out based on the characteristics of cobalt-rich crust deposits. The?experiment?result?shows?that the experimental single tooth cutting force of 1360N is close to the theoretical empirical calculation value of 1317N and the experimental power consumption of 8.55kW is close to the theoretical empirical calculation value of 8.12kW with the 2.5cm cutting depth. The result verifies the scientificity?and feasibility of the theoretical formula calculation and provides reference for the subsequent research on the exploitation technology of deep-sea cobalt-rich crust resources.
- 1
Study on the Correlation between Rock Wave Velocity and Strength ParametersAbstract:
In order to study the relationship between rock wave velocity and strength parameters, the wave velocity test, compression test, shear test and tensile test were carried out on several common rocks.Then the variation characteristics and laws of rock wave velocity and strength parameters are analyzed.The results show that the compressive strength, tensile strength, cohesion and wave velocity of rock have significant positive correlation.The change law of different kinds of rocks is similar, but also has its own characteristics.The range of change of different rocks has certain intersection, but also has obvious level.The wave velocity, tensile strength and compressive strength of sandstone with three particle sizes all show a strong linear variation law.The relationship between compressive strength, tensile strength and wave velocity of sandstone can be accurately expressed by linear fitting.The cohesion and wave velocity of different rocks are different to some extent.However, the overall trend of positive correlation, and a strong power function relationship.
- 1
Study on ground pressure law and support adaptability of working face under extremely close valley terrainAbstract:
In order to study the mine pressure behavior characteristics of working face and the adaptability of support resistance under the extremely close valley terrain in Sha Liang coal mine, through the similar simulation experiment, the mine pressure law of working face in four stages of Valley downhill, valley bottom, uphill and convex landform was studied.The experimental results show that: in the mining process of working face, there are a total of 11 periodic weighting, in the downhill mining stage, there are two periodic weighting, with an average weighting step of 19m; in the gully bottom mining stage, there are three periodic weighting, with an average weighting step of 30m; in the uphill mining stage, there are four periodic weighting, with an average weighting step of 15m; in the convex landform mining stage, there are two periodic weighting The average weighting step is 17m. With the advance of the working face, the periodic weighting step distance of the trench bottom stage is larger than that of the other three types of terrain mining stages. Through the field measurement method, the mine pressure monitoring of the mining process of 135201 working face is carried out, the relevant parameters reflecting the roof movement law of 135201 working face and the adaptability analysis of support resistance are obtained, and the rationality of support resistance of Sha Liang coal mine working face is verified. Finally, through the analysis of the obtained parameters, it is concluded that the hydraulic support zy9200/15/29 runs smoothly in the process of advancing the working face can better meet the working face support work, and effectively guarantee the safe production of the working face.
- 1
Study on the distribution characteristics of voidage under gravity compactionAbstract:
The blockage problem in ore drawing is closely related to the distribution characteristics of voidage in ore storage.On the basis of loose rock mass fractal characteristics determine ore block storage air void of different height of the loading, the loading total mass is obtained by theoretical derivation, storage level and the relation between the void fraction, combining the theory of similar simulation experiment and compare the results, the error value is less than 0.05 validation data is correct, and get the loading data fitting total mass and the relation between the void fraction, ore storage elevation;It is found that the change of voidage does not decrease with the increase of storage height. Gravity compaction will affect the voidage within the range of 7~10 m from the storage surface. When the voidage reaches the minimum value, it tends to remain unchanged and reaches the limit of voidage.Based on theoretical calculation and similar experimental results, the fractal dimension is measured according to the different gradations at unit height, and the result is proportional to the voidage.Combined with the research results, the concrete measures to rationally utilize the size of voidage and the fluidity of ore and rock are put forward in three aspects of controlling the particle size of ore unloading, the height of storage material and the ore drawing management, which has a certain guiding significance to the mine production practice.
- 1
The diffusion model of anchoring force and optimization of support parameters in composite roofAbstract:
In order to study the diffusion law of anchor force in composite roof and the design optimization method of support based on it. Taking 3306 track roadway of Daiyang coal mine as engineering background. Based on the stress diffusion effect, beam bending theory and in-situ monitoring method, the anchoring force diffusion model of single bolt in composite roof and the bolt spacing optimal design model are established, and models is verified by field engineering test. When the anchorage stress passes through the interface of composite roof rock, the stress attenuation and the sudden change of stress diffusion angle are the essential reasons for the difference of anchorage stress distribution between composite roof and homogeneous rock. The support scheme based on the optimization model can ensure the roof safety and increase the bolt spacing by 180 mm compared with the original scheme. The row spacing between bolts increases logarithmically with the in-crease of the thickness ratio of the lower and upper strata, and exponentially with the increase of the elastic modulus ratio of the lower and upper strata. The yield stress of bolt has the greatest influence on the bolt spacing, followed by the thickness and elastic modulus ratio of immediate roof and upper strata, Because the elastic modulus of roof is not easy to change, the reasonable length anchor with larger pretightening force is preferred in the optimization of support. The research conclusions provide theoretical basis for the support theory and support design optimization scheme of composite roof.
- 1
Study on cyclic loading unloading constitutive model of rock based on modified Griffith criterionAbstract:
In order to explore the failure process of rocks under periodic loads in underground engineering, multi-component grade sandstone cyclic loading and unloading tests were carried out.Based on the assumption that the infinitesimal strength of the rock obeys the modified Griffith criterion and the failure obeys the Weibull probability distribution, the rock damage theory is introduced to establish uniaxial and triaxial sandstone damage constitutive models.Through the comparison of constitutive model and test data fitting, the results show that: the fitting effect is above 0.99, that is, there is a high similarity between the two, so the model will be able to describe the failure process of rocks under the action of periodic load in underground engineering, and has a certain rationality and effectiveness.In addition, a reasonable modification of the constitutive model and a modified expression will provide a new idea for studying the failure process of rock loading and unloading.
- 1
Experimental Study on Coupled Motion of Deep Sea Mining System in WavesAbstract:
The coupling dynamic analysis of deep-sea mining vessel and lifting pipe system have a great significance to the research and application of mining system.In order to research the coupling dynamic response between the mining vessel and the lifting pipe caused by waves, the equivalent truncation design principle is adopted to optimize the characteristic parameters of the truncation model, such as elastic modulus, axial stiffness and mass per unit length, and the reasonable truncation model parameters are obtained. Based on the similarity theory, a 5000m deep-sea mining lifting pipe coupling dynamic test model is established, which solves the problem of model test of deep-sea mining system under the condition of limited test water depth. At the same time, the coupled motion experiments of deep-sea mining system model under different wave height, different wave direction angle and different buffer mass are carried out. The results show that wave height, wave direction angle and buffer mass have great influence on the amplitude and coupling time of coupling response. The establishment of the test model provides experimental support for the subsequent study of pipeline stability and heave compensation characteristics.
- 1
Study on attenuation law of overpressure of blasting shock wave at tunnel entranceAbstract:
Based on the blasting project of Zhaike Tunnel of JiNan, the attenuation law of shock wave overpressure at tunnel entrance was studied by theoretical analysis, field monitoring and numerical simulation. Firstly, the tunnel shock wave is simulated by ANSYS/LS-DYNA finite element software, and the simulation results are compared with the field monitoring data. The maximum error is less than 10%, which verifies the feasibility of the numerical simulation. Then, using the established numerical model, the attenuation of shock wave overpressure at the entrance of full-section millisecond blasting tunnel is systematically studied. Finally, surfer software is used to draw the contour map of overpressure extreme value of tunnel entrance shock wave, and the attenuation law of tunnel entrance shock wave is analyzed. The results show that the distribution of shock wave overpressure at the tunnel entrance is symmetrical about the central axis; On the extension line of tunnel wall, the overpressure of shock wave is not a simple attenuation process, but first increases and then decreases; In the outward extending direction from the tunnel entrance, the central axis outside the tunnel entrance extends to both sides, and the time to reach the peak overpressure of shock wave increases slightly, and after reaching the peak overpressure, it decreases rapidly, but the duration of positive pressure increases.
- 1
Research on the Failure Law of Drilling CoreAbstract:
Taking the geological exploration drilling core of Sanshandao Gold Mine as the research background, through statistical investigation, the core failure modes are divided into three types: The core is broken into a bumpy pie, the core is broken longitudinally, and the core is cracked without breaking. Based on the lithology and in-situ stress environment of the mining area, it is analyzed by 3DEC numerical simulation. By monitoring the radial stress distribution of the core under the condition of bi-directional equal confining pressure, in the elastic stage, the stress is mainly concentrated under the bottom of the core, and through the maximum principal stress, maximum shear stress, strain energy density nephogram, it is concluded that the most easily damaged position of the core is near the outermost edge of the core bottom. Load two-way equal confining pressure, two-way unequal confining pressure and three-way confining pressure as stress conditions, and analyze the core failure forms under various stress conditions through the dynamic distribution of failure units and the dynamic cloud diagram of strain energy density. The results show that: (1) the geometric form of core failure is different under two-way unequal confining pressure and two-way equal confining load; (2) under two-way confining pressure, the fracture form of core is tensile failure at the outer edge of core and tensile shear failure at the core axis; (3) under two-way equal confining pressure, the drilling speed affects whether the core fracture occurs; (4) Under the condition of fixed three-way confining pressure, when the angle between the drilling direction and the minimum horizontal principal stress is small θ<30 degrees, the core failure position is at the bottom of the core, and when θ>30 degrees, the core will not only occur at the bottom destruction, also occur in the axial direction splitting failure. Through the above experiments, the core failure law is revealed, which provides a useful idea for the study of core failure inversion of in-situ stress and the selection of drilling orientation.
- 1
Gas conducting fractures height evolution law in overburden of fully mechanized top-coal caving mining with high gas contentAbstract:
In order to explore the fracture zone height evolution law of overlying strata in fully mechanized top-coal caving mining of high gassy thick coal seam, taking 2303 fully mechanized top-coal caving face as the research background, the influence of mining thickness, hard rock proportion coefficient, coal seam dip angle, mining depth on the development height of gas conducting fracture zone in fully mechanized top-coal caving mining was explored through orthogonal experiment, and the relationship between each factor and the height of gas conducting fracture zone was summarized. The migration characteristics of overburden strata in "two zones" of fully mechanized top-coal caving face were simulated by UDEC software. The simulation results show that the heights of caving zone and fracture zone are 21.7 m and 45.0 m respectively. The bench subsidence phenomenon is obvious. The "two zones" of 2303 working face were detected by borehole peeper. By comparing the overlying rock fractures before and after mining, the results show that the heights of caving zone and fracture zone are 20.7 m and 44.3 m respectively, which is basically consistent with the numerical simulation results and clearly present the gas conducting fractured zone height.
- 1
Effect of shear strength on rheological properties of emulsion matrixAbstract:
In order to study the effect of shear strength on the rheological properties of emulsion matrix, emulsion matrices under different shear velocities were prepared by experiments. The effects of shear strength on the fluidity, thixotropy and viscoelasticity of emulsion matrices were tested by a rotary rheometer. The results show that the emulsion matrix belongs to pseudoplastic fluid and conforms to the Herschel-Bulkley fluid model. The shear flow equation of the latex matrix under different shear velocity conditions is fitted. With the increase of shear velocity, the thixotropic modulus and thixotropic viscosity decrease, the thixotropic time lengthened, and the area of the thixotropic ring of the emulsion matrix increased, indicating that the emulsion matrix prepared with high shear velocity needed more energy to destroy the thixotropic structure and had better stability. The viscoelastic test results show that with the increase of shear velocity, the storage modulus of viscoelastic region decreases, and the strain range of linear viscoelastic region increases. The emulsion matrix exhibits viscous deformation in the low frequency region, and its loss factor increases first and then decreases with the increase of frequency. With the increase of shear velocity, the frequency at the flow point and the storage modulus in the viscoelastic region of the emulsion matrix decrease.
- 1
The Design and Key Technology of Fully MechanizedDig-in TechnologyAbstract:
In view of the shortcomings of 3D (three dimensional) virtual simulation in fully mechanized excavation process, such as strong interaction and high fit of scene, the implementation method of virtual simulation system based on unity3d is proposed. Taking the fully mechanized excavation site of a mine as the real scene, the method of Unigraphics modeling and 3D MAX is applied to build the virtual scene of fully mechanized excavation process and make the motion simulation of each part of the fully mechanized excavation process equipment. Through the interactive interface, the interactive motion of each part is realized. Finally, the model file is imported into the unity3D system platform for motion simulation interactive design. According to the learning test results, the system realizes the visual interactive simulation operation of comprehensive mechanized roadway excavation technology, and the conversion between the operation modules is smooth. The system is easy to operate, the effect is clear, and the practical operation is strengthened. It is suitable for pre job training of enterprise workers, practical operation training and experimental teaching of college students. It is very helpful to enrich the learning process and enhance learners' interest in roadway excavation technology.
- 1
Study on the structure optimization of dust measurement pipeline combined with Karman vortex street and Bernoulli effectctAbstract:
In order to solve the problem of low measurement accuracy in low dust concentration environment when using charge induction method to measure dust concentration, a combined measurement pipeline structure based on Bernoulli effect and Karman vortex street effect is proposed. Vortex street body is added in the effect section of Bernoulli pipeline, and two fluid effects are superimposed to increase the flow rate to improve the induced electricity of dust particles at the ring electrostatic induction device, So as to improve the measurement accuracy of electrostatic induction device. Fluent is used to simulate and calculate the gas-solid two-phase flow, and MATLAB is used to calculate the amount of charge carried by dust particles with different sizes through the ring electrostatic induction device. The results show that the average induced charge of dust particles with the combined structure of Karman vortex street and Bernoulli effect is increased by 26.10%, and the induced charge of dust particles with small particle size is more obvious at 7.07% μ 36%, which improves the measurement accuracy of electrostatic induction method in small particle size.
- 1
ELECTROSTATIC INDUCTION COAL DUST MEASUREMENT DEVICE BASED ON AIR AMPLIFIERAbstract:
In order to solve the problem of inaccurate measurement of the existing electrostatic induction coal dust measurement device when the coal dust concentration is low or the velocity is low; the measurement pipeline is optimized and improved according to the principle of the air amplifier， and the compressed air is used as the power source to improve the speed of coal dust， which can improve the accuracy of coal dust concentration measurement by increasing the charge signal of the sensing electrode. Fluent software is used to establish an experimental model. The velocity cloud map of coal dust particles in the pipeline is obtained， after simulating the gas-solid two-phase flow of the optimized measurement pipeline. And Matlab is used to calculate the induced current value of the device. The simulation experiment results show that， with the air amplifier， the velocity of coal dust is much higher than the velocity provided by the dust exhauster， and the calculation of the induced current value can be increased by 757.24%， which improves the accuracy of coal dust measurement effectively.
- 1
Study on the cylindrical Micro-slump and Yield Stress of Paste SlurryAbstract:
Slump is an important index of paste filling slurry fluidity, which reflects the smoothness or difficulty of paste flowing in pipeline to a certain extent. The traditional ASTM standard slump cylinder needs a large number of tailings and occupies a large area, so it is suitable for on-site testing but not suitable for colleges and universities to carry out slump testing. The purpose of this study is to explore a reasonable miniature cylindrical slump cylinder suitable for paste filling. This paper establishes a mathematical model between the degree of slump and yield stress, and finds that the cylindrical slump cylinder has more advantages in the measurement of paste slump. By using self-made micro-cylindrical slump cylinders with different height-diameter ratios and standard slump cylinders to carry out slump experiments, it was found that micro-cylindrical slump cylinders can better reflect the fluidity of paste. The yield stress is calculated by mathematical model, which is consistent with the yield stress measured by rheometer. Through the comparison of linear regression accuracy and error analysis, a cylindrical slump cylinder with a height of 100 mm, a diameter of 67 mm (height-diameter ratio of 1.5:1) and a material of 0.352 L was selected to replace the standard slump cylinder for paste fluidity test, which provided a more direct and effective method for paste slump test.
- 1
Study on the variation law of average wind speed under complex flow fieldAbstract:
：Mine wind measurement is one of the important indicators to support mine production.Based on the simulated mine ventilation model and Fiuent numerical simulation technology, the simulated mine ventilation experiment and three-dimensional physical model under the turning roadway were constructed to simulate the influence of the distance under the wind and turning flow field, and the roadway diameter was used as the judgment criterion to classify the affected flow field.Through experiment and numerical simulation, it can be obtained that the measured value of the wind speed sensor in the flow field at 10 diameter from the turn is approximate to the average wind speed value, and the average wind speed is less affected by the roadway turning.At the corner after the roadway in 2-8 times the diameter of the semicircle is a small part of the regional wind speed value approximation is close to the average wind speed, regional position from the bottom of 1/4 length, along the roadway centerline to the lateral migration of roadway, the scope of offset for 1/4 of floor length, there is also a rectangular tunnels approximate average wind speed range, is only 1/5 of the smaller scale for floor length.
- 1
Study on optimization simulation of stope stoping sequence based on objective weighting methodAbstract:
In the underground mining of metal mines, the layout of stope structural parameters and the sequence planning of stope stoping play a key role in the safety of deep mining.In order to select the best mining sequence scheme, a comprehensive evaluation index system was established based on objective weighting method, including maximum principal stress, minimum principal stress, roof settlement displacement and technical and economic indexes.The grid model of ore body is established by using the coupled numerical modeling method of CAD-MADIS (GTS NX) -FLAC3D, and the stoping sequence of parallel stoping and step stoping is simulated and analyzed. The comprehensive evaluation of different stoping sequences is carried out by constructing the CRITIC weight evaluation model.The results show that the maximum principal stress of stope and roof settlement displacement decrease with the increase of the distance between parallel mining and step mining. Under the same approach layout, the maximum principal stress and roof settlement displacement of step mining are less than those of parallel mining.The minimum principal stress of different stoping schemes is still compressive stress without tensile stress, and the minimum principal stress also decreases with the increase of the distance.The stope mining is more stable because of the smaller interval approach pressure and roof settlement displacement in the step stoping with three mining intervals.The evaluation results of objective weighting method show that the stope stoping scheme with one step stoping at three intervals is the best one.
- 1
Study on the Application of New Inhibitor on the Separation of Copper and Fine TalcAbstract:
The flowsheet of reverse flotation talc-- flotation sulfide ore is used for a high-talc copper polymetallic ore,and the talc product contains 0.107% Cu, with fine particle size.The fine copper is difficult to recovery.A new talc inhibitor was used for the separation test of copper and talc sludge, and a copper concentrate with the Cu grade of 15.16% and a recovery rate of 60.92% was obtained. The fine copper in the talc sludge was effectively recovered and the copper recovery rate was improved.The new talc inhibitor has stable properties, good inhibitory effect, low drug consumption, non-toxic and pollution-free, and is a new type of high-efficiency and environmentally-friendly mineral agent.
- 1
Research on underground personnel detection based on Improved YOLOv4 algorithmAbstract:
At present, mining enterprises attach great importance to the safety of underground workers. Aiming at the problems of low light in underground working environment, many interference factors, low accuracy and slow speed of commonly used downhole detection methods, they proposed a research on underground personnel detection based on the YOLOv4 algorithm, and introduced information. Entropy k-means clustering determines the center point of target detection and improves the network's ability to extract target features. Experimental results show that using GeForce RTX2060 graphics card, compared to the commonly used SSD and Faster R-CNN personnel detection algorithms, the improved YOLOv4 algorithm improves the detection rate. The average detection accuracy mAP reaches 97.72%, and the detection speed is 32FPS, reaching downhole personnel. The need for real-time detection.
- 1
Sectional support technology for surrounding rock of crossing-layer roadway under coal seam floorAbstract:
For the coal seam floor crossing roadway, due to the different influence of mining on the roadway with different floor vertical depth, the failure of surrounding rock is quite different, therefore, different methods of surrounding rock control must be adopted for the roadway with different floor depth. This paper takes the East Rail uphill connection roadway under the floor of 3 upper coal seam 607 working face in a mine as the research object, the failure degree and scope of roadway surrounding rock in different depth of coal seam floor are studied by theoretical analysis and numerical simulation. In order to facilitate the site, different reinforcement and support schemes are adopted for the roadway with different depth of floor, according to the failure degree and scope of surrounding rock, it is determined that the east rail upper mountain connecting roadway is divided into three sections according to the vertical depth of the floor 5-10 m, 10-20 m and above 20 m. In view of the deformation and failure of surrounding rock in three depth segmented floor crossing roadway, different segmented reinforcement support schemes are proposed. The numerical simulation results show that the segmented support scheme can effectively reduce the deformation and failure of surrounding rock of roadway under floor, and the maintenance condition of floor roadway with different vertical depth is good. This paper has a certain reference significance for the surrounding rock control of the roadway under similar conditions.
- 1
Research and application of new footwall stoping technology of gently inclined medium thick orebodyAbstract:
In the process of underground mining in metal mines, sublevel caving without pillar is widely used. When using sublevel caving without pillar to recover gently inclined ore body, a large amount of ore loss and dilution will occur in the foothall of ore body, which increases the difficulty of mining, wastes mineral resources and reduces the economic benefit of enterprises. In order to solve the above problems, taking a mine as an example, a new technology of sublevel caving without pillar is put forward to improve the foothall recovery rate when mining gently inclined medium thick ore body. Through the research and field application of this new technology, it is shown that compared with the original mining method, when the loss rate of ore block is basically unchanged, the new technology increases the recovery rate of ore block by 6.24% by adding a small amount of engineering, and reduces the difficulty of ore body foothall recovery, and the economic benefit of mine is increased by 2.95%. The proposal and application of the new technology provide a new idea and corresponding mining experience for the efficient mining of similar mines.
- 1
Study on fractal characteristics of pore structure of pyrolysis coal by nuclear magnetic resonance technologyAbstract:
In order to study the changes in the pore structure of coal after heat treatment, low-field nuclear magnetic resonance (NMR) technology was used to obtain the transverse relaxation time (T2) of coal treated at different temperatures,According to the signal intensity of different T2, the pore content of different pore diameters is corresponding, and then the law of pore characteristics changing with temperature is obtained.Use stereoscope to obtain microscopic photos of coal surface, and use Matlab digital image processing method to assist in observing the surface change process and phenomenon after heating.Fractal analysis is performed on the nuclear magnetic data, and the fractal dimension Dx of each aperture interval and the overall fractal dimension DNMR are obtained. The results show that: micropores have the greatest influence on DNMR, which is proportional to each other, but has little correlation with temperature and total porosity.
- 1
Parameter analysis and wear law of filling pipeline in Daye Iron MineAbstract:
The empirical formula and FLUENT numerical simulation software are used to study the gravity conveying parameters and the wear law of the pipe network of the filling pipeline in Daye Iron Mine to ensure that the filling slurry can be transported by gravity and prolong the service life of the pipeline. The results show that the critical velocity of the 60% ~ 70% filling slurry in the Daye Iron Mine is 0.826 ~ 0.869 m/s, and the critical diameter of the filling pipeline is 0.143 ~ 0.146 m. When the conveying flow rate is 50m3/h, the gravity conveying of 60% ~ 70% concentration filling slurry can be realized; the numerical simulation shows that the closer the slurry is to the pipeline centerline, the greater the velocity is; the velocity will increase abruptly at the inflection point of the pipeline; at the horizontal pipe section, the velocity of slurry at the bottom is significantly higher than that at the upper part; the more serious parts of pipeline wear are at each inflection point and the other The adjacent vertical pipe section, the transition part of the horizontal pipe section, and the bottom wall of the horizontal pipe section. Through this study, the parameters of Daye iron ore filling pipeline to realize gravity transportation and the position of pipeline easy to wear during slurry transportation are obtained, which provides the parameter basis for Daye Iron Mine in pipeline transportation, effectively prolongs the service life of transportation pipeline and reduces the maintenance cost of the pipeline transportation system.
- 1
STUDY ON SURROUNDING ROCK DEFORMATION OF GOB-SIDE ENTRY IN THICK COAL SEAM WITH DIFFERENT PIAALR WIDTHAbstract:
In order to explore the deformation characteristics of surrounding rock in gob-side entry of thick coal seam under different width of coal pillars, numerical models with different width of coal pillar of surrounding rock deformation of gob-side entry were established by FLAC3D numerical simulation software. By selecting the reasonable parameters and operating of the numerical simulation models, the roof subsidence, floor heave and ribs deformation of the two sides of the gob-side entry were analyzed in detail under different width of coal pillar. The results show that with the increase of the width of the coal pillar, the roof subsidence, the floor heave and the ribs deformation of the two sides of the gob-side entry decrease. That means the surrounding rock is more stable. Maximum roof subsidence is at the middle of roof. Maximum floor heave is at the middle of floor near the gob. Maximum non-mining rib deformation is at the middle of the rib near the floor. Maximum mining rib deformation is at the middle of the rib near the roof.
- 1
Study on distribution law of three dimensional spontaneous combustion zone in goaf at different stages of fully mechanized top coal cavingAbstract:
Based on the basic theory of coal and rock caving in fully mechanized top coal caving goaf, a dynamic difference model of air leakage caused by the difference of mechanical properties between open cut and normal advancing surrounding rock caving is proposed. Considering the changes of air leakage, heat storage environment and coal low-temperature oxygenation performance caused by long-term exposure of caving surrounding rock, the characteristics of three-dimensional spontaneous combustion zone in goaf at different stages are numerically simulated and simulated Field test. Fluent simulation shows that: in the early stage of advancing, the air leakage near the gateway and the open cut is large, the obvious "O" ring phenomenon is formed after the caving and compaction in the middle of the goaf, and the range of spontaneous combustion zone is 15.7 ~ 52.5m; in the vertical direction of space, with the increase of height, due to the hysteresis of caving, the air leakage from the open cut and the middle and upper parts near the working face gradually increases to the goaf; the normal advancing is normal In the process stage, the air leakage from the two crossheading to the back of the goaf gradually weakens, the range of spontaneous combustion zone is 25.5-40.5m, which is smaller than that of open cut, but the boundary between spontaneous combustion zone and heat dissipation zone moves back by 9.8m; the field measurement of 3105 working face in a mine in Southwest Shandong shows that the range of spontaneous combustion zone of open cut is reduced from 14.9-60.5m to 24.25-40.95m, and the measured values are consistent with the simulation results. The research conclusion has important practical and guiding significance for guiding the fire prevention and extinguishing work of goaf in different stages.
- 1
Mine Image Enhancement Method Based on the Adaptive MSRCP AlgorithmAbstract:
One of the most important means to ensure the safety of mine production is mine video monitoring technology whose image quality is directly related to the effectiveness of monitoring. Multiscale Retinex algorithm is widely used in mine image enhancement. In order to achieve the best effect, it is often necessary to manually adjust the parameters such as Gaussian scale, gain and offset. This paper proposes an image enhancement method based on the Adaptive MSRCP algorithm to solve this problem, which uses Particle Swarm Optimization to adaptively adjust the Gaussian scale parameters, gain parameter, and offset parameter of the Multi-Scale Retinex algorithm with color protection. We designed a comparative experiment with standard Retinex method in different mine environments. The experimental results show that the proposed method can effectively suppress noise and halo when mine images are enhanced, and has some improvement in color and edge processing. In the experiment of mine monitoring image enhancement, the average value, variance, information entropy and PSNR are improved by 5.09%, 21.56%, 1.33% and 8.51% compared with the traditional msrcp algorithm.
- 1
Research and Application of Safety and Green Key Technology in Underground Mining of a Metal MineAbstract:
In view of the problems that the bottom mining structure of-120 m middle section is easily affected by the lower mining blasting, the rock Pu 's hardness coefficient is generally low in the roadway driving efficiency, the blasting difficulty of the cutting well of the high-segment inclined ore body is large, the lower plate of the ore body is easy to accumulate, and the cost of underground waste rock discharge is high, a metal mine adopts the field test method to study the bottom structure protection of the auxiliary middle section and the improvement of the filling roof connection rate, the optimization of the charging mode of the roadway driving, the high-efficiency deep hole caving of the inclined medium-thick ore body and the underground waste internal discharge. The results show that the project protects the bottom structure of the auxiliary middle section and improves the roof connection effect of the filling body. The cooperative operation of 2 # rock emulsion explosive and field mixed emulsion explosive can realize the safe and rapid driving of the roadway.
- 1
Experimental Research on Beneficiation of Copper Ore in Huogeqi, Inner MongoliaAbstract:
Inner Mongolia Huogeqi Copper ore concentrator uses butyl xanthate as copper collector and No.2 oil as foaming agent. Through the process of "one roughing, two scavenging and three cleaning", the copper concentrate with concentrate grade of 20.00% and copper recovery of 94.00% can be obtained. In recent years, with the deep mining of Huogeqi Copper Mine, the grade of raw copper ore is decreasing year by year, and the output of copper metal is decreasing. In order to increase the economic benefit of the enterprise and improve the comprehensive utilization rate of mineral processing resources, a detailed process mineralogy study is carried out on the ore, and the distribution characteristics of copper ore are found out. On the basis of process mineralogy, two measures are adopted in the test: one is to adopt the process mineralogy The second is to develop a new type of high-efficiency copper collector xk419. The combination of xk419 and pentyl xanthate can strengthen the recovery of copper minerals lost in tailings, especially the recovery of some copper mineral intergrowth, and improve the recovery rate of copper concentrate to more than 95.00%. In the final closed-circuit test, under the condition of grinding fineness of-0.074mm accounting for 75%, lime as pH regulator, Wuhuang + xk419 as combined collector, bk201 as foaming agent, lignin as fine three inhibitor, adopting the process of "one roughing, three cleaning, two scavenging, roughing concentrate regrinding", the copper content of 24.25% and silver content of 6.25% can be obtained under the condition of raw ore containing 1.04% copper and 4.59% silver 70 g / T, copper recovery 95. 24% and silver recovery 62. 00%. Compared with the original process, the copper grade of copper concentrate in the new process increased by 4. 10% and the copper recovery of copper concentrate increased by 0. 92%.
- 1
Design and application of underground mine roadway support based on rock mass quality classificationAbstract:
In order to improve the classification accuracy of rock mass quality, the extension theory is introduced to build a comprehensive evaluation model of rock mass quality based on game theory and extension theory. Firstly, six indexes such as RQD are selected to establish a comprehensive evaluation index system of rock mass quality. Secondly, G1 method and entropy weight method are used to determine the subjective weight and objective weight of indexes respectively, and the comprehensive weight of indexes is calculated based on game theory Finally, the model is applied to the evaluation of the surrounding rock quality of an underground mine roadway, and the results show that the evaluation results of the model are reasonable, reliable and applicable. Finally, based on the results of rock mass quality classification, the support scheme is designed, and FLAC3D is used to simulate the support scheme. The results show that the support can effectively control the deformation of surrounding rock, and the satisfactory effect is obtained.
- 1
Research on an automatic roadway formation method by roof cutting with high-strength coal ribAbstract:
In order to solve the problems of roadway deformation caused by coal rib breaking of roadway formed by roof cutting, an automatic roadway formation method by roof cutting with high-strength coal rib was put forward. The self-supporting capacity of coal rib is improved by strengthening the anchor cable, and the surrounding rock of roadway is located in the low stress area by roof cutting. Taking Xinyi Coal Mine as the background, the coal roof deformation analysis model is firstly constructed, and the relationship between different broken widths of coal rib and roof deformation is studied. The results show that coal rib breaking will lead to large roof deformation, and the roof deformation rate increases with the increase of broken widths of coal rib. Then, carry out the different cutting angle, cutting height, coal rib anchor cable length, angle of anchor cable at top and bottom of coal rib numerical experiments under the influence factors such as, set up for the roof convergence rate, coal wall convergence rate and strength of anchor cable utilization, hydraulic prop strength utilization of quantitative evaluation index, the contrast analysis of the single roof cutting and coal rib reinforcement combined with roof cutting two cases of roadway deformation and supporting component pressure. The results show that the convergent deformation of the coal rib reinforcement combined with roof cutting roadway is further reduced compared with that of the single roof cutting. The displacement of the coal wall is about 61mm, which decreases by 34.8%, the displacement of the roof is about 80mm, which decreases by 34.4%, and the safety margin of the anchor cable is increased by 14.9%. Finally, this technology was applied in 1706 roadway of Xinyi Coal Mine, and the monitoring results show that this method effectively controlled roadway deformation and achieved good effect of roadway retention. The research results can be used as reference for gob-side entry retention under similar geological conditions.
- 1
Numerical Simulation Research on Mining of -38m~-50m Orebody in Yongping Copper MineAbstract:
Taking the open-pit stope slope and the open-pit and underground combined mining isolation layer in Yongping Copper Mine as the research object, the influence of -38m~-50m orebody mining on the slope and isolation layer is comprehensively analyzed based on numerical simulation and slope stability results by using the CAD- Rhino-FLAC3D coupling modeling method. The results show that the ore-body mining in this area will reduce the safety factor of the slope and make the slope in an understable state. With the mining of -38m~-50m orebody, the plastic zone area of the isolation layer gradually increases and exceeds the yield limit, and the stress and displacement values increase. Moreover, tensile stress appears on the slope and the surface of the isolation layer. Taking into consideration, the mining of this part of the orebody has great safety risks, so it is suggested to retain the -38m~-50m orebody and not to mine.
- 1
Study on mechanical properties of EVA and steel fiber modified concreteAbstract:
In this paper, a new type of polymer modified concrete used for roadway repair and side filling was obtained by studying the influence of different amount of ethylene - vinyl acetate copolymer (EVA) and steel fiber on the mechanical properties and durability of concrete, and the optimum ratio of each component was determined.The results show that EVA will reduce the compressive strength of concrete, and when the content reaches 15%, the plastic deformation ability and ductility of concrete will be better improved.Steel fiber will improve the strength and ductility of concrete, when the volume dosage is 1.5%, the increase is more;In group C, when the volume content of steel fiber was 1.5%, the mechanical properties of all aspects improved less than that of the volume content was 1%.The C3 test has the best effect, which significantly improves the plastic degeneration and ductility of concrete, increases the splitting tensile strength by 6.1%, the flexural strength by 29%, the mid-span deflection by 420%, and the elastic modulus by 3.25 GPa to 1.12 GPa, which greatly improves the mechanical properties and durability of concrete.
- 1
RESEARCH AND APPLICATION OF ROOF CONTROL REPAIR TECHNOLOGY FOR ROOF FALL ROADWAY IN SUPPORT AREAAbstract:
When the roof of the roadway fell to varying degrees, a roadway in Jiaojia Gold Mine was supported by U-shaped steel + channel steel roof. The U-shaped steel roof and a bunch of them fell to different degrees due to the influence of mining in the later period, which is more difficult to repair. The rock mechanics is used to analyze the causes of roof failure in the roadway in the support area, and a technical scheme of diamond support + foaming material filling and roof control is proposed. The ratio of foaming material A and B is 1:0.95 through experimental comparison, the foam has the highest strength and stable performance. Finally, a technical solution of rhombus support + foam material (A:B=1:0.95) filling and roof control was proposed. Using numerical simulation and field test methods, the stability of roof fall roadway filling control in the support area is analyzed and evaluated. Theoretical analysis and on-site industrial tests have proved that the use of diamond-shaped support + foam material (A:B=1:0.95) filling and roof control technology for roof-falling roadway filling and roof-controlling support can ensure that this type of roadway is under the action of mining stress. stability.
- 1
Study on Optimization of Mining Scheme of Inclined Medium-thick Orebody in Hainan Iron MineAbstract:
The Baoxiu mining area in the Hainan Iron Mine is an inclined medium-thick to thick orebody with poor ore rock stability, which is mined by the non-pillar sublevel caving. The previous stoping drift is arranged perpendicular to the orebody strike. Considering that the occurrence of ore body revealed by production exploration is complex and the thickness and angle of the branching of branching orebody is great, the previous stoping drift leads to large amount of preparatory engineering and high expected loss dilution rate. Based on this problem, the stoping drift arranged parallel to the strike of the orebody is proposed. Meanwhile, the ore loss dilution and roadway support cost in two types of approach directions are comprehensively compared. The results show that the ore loss rate of footwall can be reduced 10.91 percentage points and the amount of preparatory work can be saved 28.4% when the approaches are arranged along the vein. In addition, based on the making full use of the existing engineering of the mine, the optimization of mining scheme mainly used the sublevel double-approach stope structure to reasonably recover the ore in footwall and induce the unstable surrounding rock caving at the same time is proposed. The optimized mining scheme can better adapt to the change of orebody occurrence and increase the economic benefit of mining.
- 1
Algorithm to Improve The Efficiency of Dynamic Sequencing Optimization of Production Schedule in Open-pit Coal MinesAbstract:
The general dynamic sequencing optimization model of production schedule in open-pit coal mines. In the process of optimizing the three elements of production capacity, mining sequences, and mining life to obtain the best plan, it is necessary to limit the upper and lower limits of the production capacity; too narrow the interval may miss the best production capacity, if the interval is too wide, it will take a long time. In view of this, this paper presents a mobile domain algorithm and a random fluctuation algorithm to solve the problem. The mobile domain algorithm moves the annual production capacity constraint interval successively according to a certain interval width, and calculates the “local best plan” in the constraint interval of each movement. After the constraint interval covers the upper and lower limits of the production capacity, select from all the “local best plans”. The global best plan is obtained; while the random fluctuation algorithm is to randomly fluctuate the production capacity of the best plan obtained in the mobile domain algorithm to obtain a new best plan, and verify whether the best plan of the mobile domain algorithm is optimal by comparison. The application case results show that the general dynamic sequencing optimization model combined with he mobile domain algorithm and the random fluctuation algorithm to optimize the production schedule of open-pit coal mines takes 4 minutes, which is 750 times faster than the 50 hours optimized separately, and the efficiency has been significantly improved.
- 1
Thinking about the connotation and realization path for green mining in ChinaAbstract:
The development of green mining is a significant action under the new situation to carry out the ecological civilization construction in China. How to understand, implement and improve green mining is the key to resolve the problems of insufficient and unbalanced development of green mining. To explore this question, the green development ideal of harmony between human being and nature was clarified from the perspective of policy evolution. And this paper explained that green mining was a mining development mode which took ecological priority as the principle and aimed at realizing the coordinated development between economic social system and ecological environment system based on the concept differentiation. By the analysis of elements, the components system of green mining was constructed with the "three-dimensional" perspective including multi-scale, multi-subject and multi-link. On this basis, the realization path for green mining was discussed, which provided demonstration and reference for further establishing the development mode of green mining.
- 1
Application of 3D simulation technology in the treatment of deep well heat hazard in Daliuhang gold mineAbstract:
With the continuous increase of mining depth, underground ventilation system becomes more and more complex, which leads to more and more obvious problems of mine heat damage. For metal mine deep well effective governance, heat harm problem with big mouth I LiuXing gold mine mining area hot against the status quo, for example, the thermal simulation analysis, 3 d simulation technology using Ventsim software simulation scheme of the original ventilation system and governance, through the analysis of simulation results, to determine the best solution, and to simulate the final plan in advance, to predict mining homework late thermal pollution governance effect. The results show that the simulated deviation rate is within the allowable range of design, and the application of heat damage control scheme can effectively reduce the temperature of deep well.
- 1
Numerical analysis on the influence of relative roughness for the Fixed-point Air Velocity Measurement Location in an AirwayAbstract:
In order to improve the accuracy of air velocity monitoring data, numerical tests and field measurements are carried out under the influence of an turning section in airflow inlet and bolt-mesh supporting in roof, two sides of the airway, which is closer to the actual situation. Combined with the field measured data, the average relative roughness of 11218 return airway and the parameters of the fixed-point air velocity measurement location are determined. The results show that the height in Z direction of the fixed-point air velocity measurement location decreases with the increase of relative roughness at the same X coordinate, and the decreasing range gradually decreases with the increase of relative roughness. In the cases of k/d = 0.03-0.06, the fixed-point air velocity measurement location are close to the roof in the X direction of about 80m. When x > 120m, the fixed-point air velocity measurement location is stable earlier with the larger relative roughness. Through comparison between field measured data and numerical results, the average relative roughness of 11218 return airway is 0.01 for the floor and 0.06 for the roof and both sides of the airway, and the maximum relative deviation between the measured air velocity and the numerical result is less than 1%. Taking the relative deviation of 0.1% as the benchmark, the accurate fixed-point air velocity measurement location of 11218 return airway is determined to be 140m after the turning section and 0.428m away from the roof of the airway.
- 1
Landslide mechanism and stability analysis of tailing dam under reservoir water level changeAbstract:
The main factor of tailing dam break is caused by the change of water level. Taking Waitoushan tailing dam as an example, this paper analyzes the influence of water level change on the stability of tailing dam by strength reduction method, analyzes the corresponding landslide mechanism, compares it with limit equilibrium method, and puts forward the standard of safety factor of strength reduction method. The results show that: the phreatic line of tailings dam rises with the rise of water level in the reservoir, and the phreatic line under normal water level is the lowest; the water level in the reservoir rises from normal water level to flood level and overtopping water level, and the instability sliding mode of tailings dam changes from push type landslide to traction type landslide; the calculation results of three-dimensional strength reduction method and two-dimensional limit equilibrium method are close, and the strength is calculated by analogy method The standard safety factors of the reduction method are 1.20, 1.30 and 1.40. The simulation results of this paper can provide a reference for improving the technical specifications of tailings dam, provide a basis for mine disaster prevention and reduction, and provide a new idea for the stability analysis of tailings dam.
- 1
Study on pillar recovery and stability of an iron mine in ShandongAbstract:
In order to continue the benign development of mine production and avoid the waste of high-grade ore, the recovery scheme of safety pillar in an iron mine in Shandong Province was designed, and the stope stability and surface displacement after pillar recovery were analyzed by theoretical analysis and numerical simulation. The stress and strain law of mine roof plate are calculated by simply supported beam model, and the profile equation of surface subsidence basin is established by probability integral method to calculate and solve the surface subsidence displacement On the basis of theoretical analysis, FLAC3D numerical simulation software is used to evaluate the stope stability before and after the stope filling in the reserved pillar, and at the same time, the surface displacement and aquifer displacement caused by pillar mining are analyzed. The research shows that: (1) the theoretical calculation shows that the maximum vertical displacement of roof is 11.8 mm, the maximum surface settlement is 16.7 mm, and the maximum surface inclination is i=0.03 mm/m, which is far less than the allowable value of Class II building I = 3 mm/m; (2) The results of numerical simulation show that the maximum subsidence of roof, the maximum displacement of surface, the maximum displacement of water-bearing area and the maximum displacement of pillar supporting roof are 37.49 mm, 10.6 mm, 14.03 mm and 17.72 mm；, respectively. (3) The overall stress of the stope is low and evenly distributed after all the stopes are mined by numerical simulation, without stress concentration, and the stability of the stope without plastic zone distribution is good; (4) Through the comprehensive analysis of theoretical calculation and numerical simulation results, it is found that all mining of the mine room in the pillar has no significant influence on the mine room, the ground surface, the aquifer and the roof pillar, thus ensuring the safety of pillar recovery.
- 1
Study on optimization of stope structure parameters in sublevel room subsequent filling miningAbstract:
In view of the potential safety hazard of personnel and equipment exposed under the roof in the existing mining method of liutangfang iron mine, the sublevel room subsequent filling mining method is recommended, and the Mathews graphic method is applied to the primary selection of stope structural parameters. On the basis of the primary selection results, according to the nine combination schemes of stope span of 50m, 40m, 30m and pillar width of 6m, 7m, 8m, FLAC3D software is applied to analyze the stope structure stability of nine kinds of stope structure schemes. Finally, the nine combination schemes are comprehensively compared from the Perspective of safety and economy. The stope span of 40m and pillar thickness of 7m are the optimal stope structure parameters. This method realizes the purpose of optimizing stope structural parameters, and can be popularized in similar mines.
- 1
Research and field application of new mining technology for thick and large orebodyAbstract:
Among the mining methods used in most metal mines at present, sublevel caving without pillar is one of the most common mining methods. In view of the problems such as low efficiency, difficulty in ventilation and difficulty in ore supply in the process of mining thick and large ore body, this paper puts forward a pillarless sublevel caving mining method with an iron mine as the engineering background, in which the central section of thick and large ore body is cut along the strike and the groove is drawn, and the upper and lower plates are vertical to the approach and mining at the same time. Through a practical application of the new type of mining technology in the mine, data analysis, show that the new application of mining technology improve the efficiency of ore mining, equipment drawing and the distance to reduce 40% to 50%, good ventilation effect, increase the quantity of ore mining and ore removal location advantages, enhance the enterprise"s economic efficiency, reduce the risk of underground work personnel coefficient. The proposal and application of new mining technology provide new ideas and corresponding mining experience for the safe and efficient mining of similar mines .
- 1
Study on Separation of Copper and Lead from Copper Lead Mixed Concentrate of a Polymetallic Ore in XinjiangAbstract:
In order to solve the problem of difficult separation and serious mutual inclusion of copper and lead in a polymetallic ore in Xinjiang, the separation process conditions of copper and lead were tested. The results show that the copper concentrate with Cu grade of 20.34%, recovery rate of 92.38%, containing 6.46% of Pb, the lead concentrate with Pb grade of 51.09%, recovery rate of 95.13%, containing 0.68% of Cu can be obtained by using mixed concentrate pressure filtration combined with activated carbon as depressant and Z-200 as collector. The separation effect of copper and lead was fine, which provided a reference for the production practice of mining enterprises.
- 1
Visual Analysis of Intelligent Knowledge Graph of Chinese Coal MinesAbstract:
With the rapid development of science and technology, the intelligent technology in the coal mine field is also improving day by day. In order to have a more comprehensive understanding of the current hotspots and development directions in the field of smart mines and coal mines, this article uses the China Knowledge Network (CNKI) database as the data source and uses The citespace software constructed and analyzed the knowledge graph of 1,399 documents in the fields of "Intelligent Coal Mines" and "Smart Mines" collected by CNKI from 2000 to 2020, mainly through the year of publication, keyword analysis, key author As well as the visual analysis of the organization, it describes in detail the overall picture of the field and the future development direction. The results show that there are a large number of authors and institutions in the field but less cooperation. The cooperation is mainly based on small-scale exchanges. Research institutions are not limited to universities, but also have a large number of research institutes and enterprises. At the same time, the research prefaces in this field are mainly Focus on "5G technology", "Internet +", "smart mine" and other aspects.
- 1
Application of fast slotting technology without raise in soft broken rock mass of West No.2 Mining Area of Longshou MineAbstract:
In order to provide free surface and compensation space for the blasting of fan-shaped blasthole, a cutting vertical groove should be formed at the end of the drift before normal mining in the stope of sublevel caving without sill pillar. The orebody and surrounding rock of no sill pillar sublevel caving stope in West No.2 Mining Area of Longshou Mine in Jinchuan are relatively broken. Under this condition, if the traditional way of "cutting drift + cutting raise" is used to form the cutting groove, there are some problems such as low efficiency and poor safety. In view of the broken ore and rock conditions in West No.2 Mining Area, a safe and rapid trenching technology scheme without well is proposed, which is "cutting drift + wedge cutting medium deep hole + parallel vertical expanding medium deep hole". The industrial test is carried out in the field, and the trenching quality and safety of the scheme are comprehensively evaluated. Engineering practice has proved that the scheme of "cutting drift + wedge cutting medium deep hole + parallel vertical expanding medium deep hole" can form cutting groove safely and quickly under the condition of soft broken rock mass, which is worthy of popularization and application in the whole caving stope of West No.2 Mining Area.
- 1
RESEARCH ON REASONABLE WIDTH OF SEGMENT PILLAR OF GOB-SIDE ENTRY RETAINING IN FACE IN THICK COAL SEAM OF DEEP SHAFTAbstract:
In order to ensure the stability of roadways and coal pillars in goaf working face of thick coal seam under deep well condition, taking 3304 working face of Zhaolou coal mine as the background, and the reasonable coal pillar width of working face is studied by theoretical analysis and stress monitoring. By analyzing the monitoring results of the working face"s lateral stress and comparing the structure of the overlying strata on the working face, the following conclusions are obtained: (1) The influence range of the advanced abutment pressure of the 3304 working face of Zhaolou Coal Mine is 125.4m on average, and the influence range of low stress in the goaf is 15m. (2) The lateral rock layers in the goaf are broken and rotated upward layer by layer, and the high rock layer (the second rock beam) is at a fracture position of about 30-40m; (3) Comprehensive consideration of the stability of the roadway along the goaf, the effectiveness of anchoring and support, In terms of the effectiveness of preventing rock bursts, the reasonable section coal pillar width is 4-6m. The research results have a certain reference value for the design of the section coal pillar width along the goaf of the deep mine thick coal seam under similar conditions.
- 1
Study on the interaction between open pit and underground combined miningAbstract:
Using modern computer numerical simulation technology, the interaction between underground mining and open pit mining is studied.Through the study of the influence of goaf formed by underground mining on the stability of open-pit slope, the influence of underground mining blasting on the stability of open-pit slope, and the influence law of open-pit blasting on the underground chamber (main shaft).The effective safety measures under different working conditions are obtained, so as to realize the safety production of open-pit mining and underground mining.
- 1
Surrounding rock control of soft rock roadway based on theory of composite bolt-rock bearing structureAbstract:
Deep soft rock roadway has always been a difficult problem for surrounding rock control in coal mine. With the increase of depth, the surrounding rock stress increases continuously, and the geological environment becomes more complex, which increases the difficulty of roadway surrounding rock control. Guizhou Panjiang Hengpu Coal Industry 21126 coal seam, roof and floor are all low-strength, broken soft rock, the surrounding rock deformation during the excavation period, and the effect of multiple maintenance was limited, which seriously affected construction safety and tunneling progress. In this paper, the theory of anchorage composite carrier is used to calculate the bearing capacity of anchorage composite carrier, the cause of roadway failure is analyzed, and the optimization scheme of roadway support parameters is put forward. The results of numerical simulation and field application show that the roadway deformation has been significantly reduced compared with that before optimization. The roadway tunneling has been around 22 days, the deformation velocity of surrounding rock has been greatly reduced. Within 32 days after tunneling, the roof subsidence of the roadway is 127 mm, the bottom heave is 73 mm, the distance between the two sides is 256 mm, and the deformation of surrounding rock is basically stable. The research results show that the optimization scheme of bolting support parameters for soft rock roadway based on the theory of anchorage composite carrier can effectively control the deformation of roadway surrounding rock and meet the needs of stability control of roadway surrounding rock, so as to provide reference and guidance for the control and support technology of soft rock roadway surrounding rock.
- 1
Naive Bayesian-based Evaluation of In-service Highway Soil-like Slope Stability in Guizhou ProvinceAbstract:
With the rapid development of expressway construction in Guizhou Province of China, there have been a large number of high-filled or deep-digging roadbed engineering slopes, and the risk of instability of these existing slopes has increased over time. Given this situation, a slope stability evaluation approach based on the Naive Bayes classification was proposed in this paper. In this approach, six parameters including slope height, slope rate, back slope angle, cohesion, internal friction angle, and supporting structure measures were determined for an index evaluation system, through the statistical analysis of geometry and mechanic properties for 948 existing highway slopes in Guizhou province. FLAC3D was employed to form a training set that covers 4800 operating conditions, and the Naive Bayesian classification model was referenced to evaluate the stability for soil-like slopes effectively. In terms of accuracy, this introduced classification model was verified by utilizing Monte Carlo cross-validation. Moreover, a rapid evaluation system analyzing the stability of soil-like slopes was established through the MATLAB design, and it was tested by the stability of a slope on the Xia-Rong Expressway. The results confirmed that the accuracy of the Naive Bayesian classification model and the stability probability are respectively 91.68% and 59.42%, which is consistent with the numerical simulation results. This practical application delivered a consistent result and verified the correctness of the proposed method in this paper.
- 1
Experiments and Microbial Community Analysis for Column BioLeaching of a Low Grade Uranium OreAbstract:
In order to explore the bioleaching performance and microbial community distribution in the column bioleaching system of low-grade uranium ores by a mixed bioleaching bacterial consortium, the liquid parameters, the surface characteristics of the passivation layer and the bacterial community distribution was investigated in the process of column bioleaching of a low-grade of granite type uranium ore by the mixed bacterial consortium (A.ferrooxidans, L. ferriphilum and A. thiooxidans). The results showed that the uranium recovery was about 82.56% in the 20 days acidic pre-leaching and 57 days bacterial leaching. The uranium recovery in the upper column layer was 1.49% higher than that in the lower column layer, which about 83.3%. Moreover, the yield of the passivation substances in the upper column layer was less than that in the lower column layer. Additionally, the community structure analysis results showed that the dominant species in the leaching solution was L. ferriphilum, A. thiooxidans and A. ferrooxidans, while the dominant species on ore surface in the upper column layer was A. thiooxidans, L. ferriphilum, and A. thiooxidans, A. ferrooxidans in the lower column layer. The results above would provide some valuable references for the practical application of uranium bioleaching using mixed bioleaching microorganisms.
- 1
Study on crack propagation law of limestone under impact loadAbstract:
In order to study the crack propagation of cracked rocks under cyclic impact, Taking the limestone from the slope of Sanyou Mine as the research object Based on the basic principle of split Hopkinson bar (SHPB), using continuous-discontinuous numerical simulation method, introducing linear elastic element model, load method by applying sine wave in the axial direction, simulate internal crack growth of limestone. Use GDEM numerical simulation software to establish a numerical model of a two-dimensional limestone sample with a length of 50mm and a height of 25mm. The crack propagation laws and mechanical properties changes of limestone with crack angles of 0°, 30°, 60° and 90° under impact load are studied. The impact damage difference of prefabricated single-crack and prefabricated double-cracked rock is compared. The research results show that: the rock initiation positions are all at the original crack tip. With the increase of the main crack angle, the peak strength of rock failure and the time of failure show a trend of first decreasing and then increasing. When the number of cracks increases, the initiation position of the crack remains unchanged, but the propagation speed to the two ends increases, the peak stress of rock fracture decreases, and the rock failure time shortens. The research results are of great significance to the analysis of slope stability with damaged rocks caused by dynamic loads.
- 1
Study on Surrounding Rock Control Technology of Gob Side Entry Retaining with Hard Composite RoofAbstract:
Through the study of the characteristics of roof movement along the gob-side roadway with the hard composite roof, the roof movement and stress evolution law of the roadway with the reserved roadway is clarified, and the transmission mechanism of the roof overburden load is obtained. Based on the evolution characteristics of the surrounding rock structure, a calculation model for the roof subsidence of the roadway is established, and the roof subsidence is controlled by the rotation subsidence of the key blocks of the hard roof and the roof separatio, the calculation formula of the final roof subsidence is given, and put forward the control strategy of asymmetric support and the calculation formula of anchor cable support strength. Taking the hard composite roof of 1102 working face in Qiuji coal mine as the research background, with the help of UDEC numerical simulation software, the displacement and stress change of the roadway roof are calculated. The results show that the roof cantilever beam after the roof cut has the characteristics of greater vertical displacement as it approaches the cutting seam, and the roof stress transfers to the deeper part, and there is no stress concentration phenomenon on the roof of the roadway. Based on this, the asymmetric support method of Constant resistance and large deformation anchor cable + anchor + single hydraulic prop is designed, and the field application effect is good.
- 1
EXPERIMENTAL ATUDY AND APPLICATION OF FILLING GRADED FINE TAILINGS THICKENING IN A GOLD MINEAbstract:
Based on the graded fine tailings with more than 80% content of - 37μm in a gold mine,Indoor static flocculation sedimentation test, indoor dynamic thickening sedimentation test and on-site semi industrial thickening test were carried out.The influence of mortar concentration, flocculant type and flocculant dosage on the settlement of graded fine tailings was studied.The matching relationship between the height of sludge layer and the underflow concentration of thickener is mastered.The experimental results show that:The results of indoor static flocculation sedimentation test and dynamic thickening sedimentation test can be used to guide the reasonable diameter selection of thickener for mine filling,However, the underflow concentration data of indoor test is lower than that of semi industrial thickening test.In a certain period of time, the underflow concentration of thickener first increases and then tends to be constant with the increase of mud layer height.The experimental data of semi industrial thickening can be used to guide the reasonable height selection of thickener for mine filling.
- 1
Intelligent?Extraction?Method?of?3D?Rock?Discontinuity Roughness and?ApplicationAbstract:
Discontinuity?roughness?is?a?key?factor?in?the?strength?of?fractured?rock?masses,?but?the?current?measurement?and?statistical?tools?for?rock?mass?discontinuity?roughness?are?mostly?limited?to?laboratory?conditions.?The?roughness?of?the?on-site?measurement?methods?and?tools?is?inconvenient,?and?the?measurement?results?are?affected?by?human?factors.?Therefore,?a?method?and?system?for?intelligently?extracting?3D?rock?discontinuity?roughness?is?proposed.?Mainly?based?on?digital?image?technology?and?deep?learning?algorithms.?First?use?the?3D?One?tool?to?build?a?three-dimensional?discontinuity?model?of?the?standard?structural?surface?contour,?secondly?use?the?image?acquisition?device?to?obtain?the?discontinuity?image?and?format?it,?and?finally?learn?the?digital?image?of?the?discontinuity?based?on?the?deep?learning?algorithm?and?the?RNN?deep?learning?network?Training?and?classification?processing,?de-normalize?the?output?result?of?RNN?and?decode?it?to?estimate?the?surface?roughness?coefficient?JRC?of?the?rock?mass?structure.?It?has?been?applied?to?the?measurement?of?discontinuity?roughness?of?jointed?rock?masses?in?the?experimental?roadway?of?Jiaojia?Gold?Mine,?and?good?results?have?been?obtained.?The?research?uses?the?non-contact?measurement?intelligent?image?recognition?technology?to?make?up?for?the?heavy?workload?of?traditional?drawing?methods?and?the?large?limitation?of?environmental?and?subjective?influences.?It?is?of?great?significance?to?promote?the?intelligentization?of?mine?rock?mechanics?field?investigation.
- 1
Experimental study on freeze-thaw damage of red sandstone pore structureAbstract:
In order to investigate the microstructure damage characteristics of rock under freeze-thaw condition, NMR, SEM, porosity and permeability measurement tests were carried out on red sandstone before and after freeze-thaw. The T2 spectrum distribution, SEM scanning images, effective porosity and permeability changes of red sandstone before and after freeze-thaw were obtained. The research results show that after the red sandstone freezes and thaws, the shape of the first peak shifts to the left, and the sum of the area of ??the first peak and the second peak increases in proportion to the total area of ??the T2 peak, indicating that the rock is freezing Micro-cracks are generated under melting conditions; the T2 spectrum distribution of red sandstone mainly has three peaks, and the area of ??the third peak accounts for less than 1% of the total peak area, indicating that there are few large pores and mainly micro-pores; scanning electron microscope images show that The number of small pores and micro-cracks in the red sandstone after freezing and thawing increased, and the pore size increased. The saturated water mass, effective porosity and permeability of red sandstone all increase after freeze-thaw. This is due to the formation of new micro-cracks in the rock under freezing and thawing conditions, which provides space for water migration. The results of nuclear magnetic resonance, scanning electron microscope images, effective porosity and permeability of red sandstone can provide a basis for studying the mechanism of rock freeze-thaw damage.
- 1
ANALYSIS OF BRITTLENESS INDEX BASED ON SIMPLIFIED ENERGY RATIO OF PRE-PEAK ENERGY TO POST-PEAK ENERGYAbstract:
Brittleness is a very important intrinsic property of rock. Rock brittleness is closely related to reservoir modification. It is an important indicator for reservoir mechanical property evaluation, wellbore stability evaluation and hydraulic fracturing effect evaluation, and construction of deep rock mass engineering. And the development and utilization of resources have guiding significance. A lot of research work has been carried out by scholars at home and abroad on the topic of rock brittleness, but there is no standard and unified definition of rock brittleness and test methods. In order to more reasonably characterize the brittleness of rock mass, a new brittleness based on the stress-strain curve and considering the ratio of the post-peak energy of the rock mass to the energy of the pre-peak energy is proposed. Indicators, and carry out uniaxial and triaxial compression experiments to test new indicators. The test results show that the brittleness of granite, red sandstone and argillaceous sandstone decreases in the same stress state, which is consistent with the actual brittleness. Under the confining pressure of 20MPa, the brittleness of argillaceous sandstones increases suddenly, which indicates that the mechanical behavior of the rock mass is also affected by the internal fissures, which should be paid enough attention in practical engineering. The test results strongly support the reliability of the brittleness index, and the research results are expected to enrich and improve the existing rock brittleness evaluation methods.
- 1
Experimental Study On Preferential Flotation of a Mixed Lead-Zinc Ore From Sichuan ProvinceAbstract:
In view of the characteristics of a mixed lead-zinc ore from sichuan with high oxidation rate and main mineral composition of galena, sphalerite, white lead, smithsonite, quartz, and dolomite, lead sulfide minerals, zinc sulfide minerals and oxide minerals recovery study was conducted according to the principle of floating sulfide minerals before oxide minerals, preferential flotation. The closed-circuit test showed that the Pb content of the two kinds of lead concentrates was 57.32% and 45.57%; zinc concentrate containing Zn 48.66%,mixed concentrate containing Pb 29.22% , Zn 20.83%. Comprehensive recovery rate of lead and zinc was 91.35% and 88.63% . Experimental study can provide reference for the development and utilization of this type mixed lead-zinc ore.
- 1
Study on the combined adsorption efficiency of water retaining agent and rhamnolipid on Cd in soil of desert mining areaAbstract:
The application of environment-friendly materials to adsorb heavy metals is one of the hot topics in soil pollution control. In this paper, green environmental protection polymer material - water retaining agent and biological surfactant rhomnolipid were used to adsorb Cd2+ in high salinity soil by single factor experiment and orthogonal experiment. The results show that the combined action efficiency of the two materials is higher than that of single adsorption, and the adsorption rate reaches 98% at 45℃.The optimum adsorption time was 3h. Under alkaline conditions, the combined adsorption efficiency of Cd2+ is higher. The effect of increasing rhamnolipid concentration on the adsorption rate was firstly decreased and then increased, and the adsorption rate reached the maximum when the concentration reached 2g/L. The adsorption rate reached 99% when the water and soil ratio was 5:1. The increase of the amount of water-retaining agent will increase the adsorption rate, and the adsorption rate tends to be stable in a certain range when it reaches saturation. The orthogonal experiment showed that the main factors affecting the adsorption of Cd2+ were the concentration of rhamnolipid > pH >time >retention agent. The optimal adsorption combination was designed as 0.05g of water-retaining agent, 1g/L rhamnolipid concentration, 9h, pH10.The experimental results provide a new idea for soil remediation and ecological remediation in arid desert mining areas.
- 1
EXPERIMENTAL STUDY ON THE COPPER-MO ORE PROCESSING AND THE REUSE OF TAILINGSAbstract:
A mineral processing experiment was conducted on the recovery of copper and molybdenum and the reuse of tailings water from a copper-molybdenum ore . The selected raw ore are Cu0.43% and Mo0.021%. The copper-molybdenum mixed flotation-copper-molybdenum separation flotation rough concentrate regrind and re-separation process is adopted. The final mineral processing index obtained: the copper concentrate contains Cu20. 79%, whose recovery rate is 90.18%; the molybdenum concentrate contains Mo46.27%, and its recovery rate is 68.30%. The waste water generated in the whole process test is placed for 48 hours and then reused. It has little effect on the copper flotation index, but it will affect the molybdenum flotation index. Keywords: copper-molybdenum ore,mineral processing,tailings water,reuse
- 1
The driving effect of resource exploitation to regional economyAbstract:
Regional economic benefits driven by resource exploitation are calculated to provide quantitative evaluation basis for sustainable development of mining areas. Based on resource attributes and mining characteristics, industry characteristics and influence range, this paper establishes a calculation model of profit of mining service industry, resident wage income, benefit of scientific and technological output and benefit of downstream industry development. On the basis of national statistical data, extract effective information and calculate relevant parameter values. Combined with the case mine resource conditions and design scheme, the impact of resource mining on the development of related industries and economic benefits are analyzed. The results show that resource exploitation has a great driving effect on regional economic development, especially in the input and output of science and technology.
- 1
RESEARCH ON THE EFFECT OF INTERFACIAL WATER PRESSURE ON TRIAXIAL MECHANICAL PROPERTIES OF COAL-ROCK COMBINATION WITH DIFFERENT INCLINATION ANGLESAbstract:
In order to study the stability of the coal-rock interface in the indirect coal-bed methane fracturing project, triaxial compression tests of coal-rock combinations with unbonded free interface at three angles of 15°, 30° and 45° under dry and water saturated states and triaxial compression tests of coal-rock combinations with 30° inclination angles under different interfacial water pressures were carried out. It reveals the influence mechanism of interface inclination angle and interface water pressure on the mechanical properties of coal-rock combinations. The results show that the strength of the unbonded interface coal-rock combination decreases with the increase of the interface inclination angle. Under water saturated state, when the inclination angle increases from 15° to 45°, the triaxial compressive strength decreases from 36.91MPa to 7.84MPa, a drop of 80%. And the failure mode of coal-rock combination changes from the splitting failure of the coal body at 15° to the shear slip failure of the interface at 30° and 45°. The saturated state has a weakening effect on the strength of coal-rock combination, and it decreases with the increase of the inclination angle. When the inclination angle is 15°, the strength decreases from 50.83 MPa to 36.91 MPa, a decrease of 27%, and when the inclination angle is 45°, the strength decreases from 8.72 MPa to 7.84 MPa, a decrease of 10%. The peak strength and residual strength of coal-rock combination have a negative linear relationship with the interface water pressure. As the interfacial water pressure increases from 0 to 4 MPa, the peak strength decreases from 18.53 MPa to 11.67 MPa, and the residual strength decreases from 13.35 MPa to 8.84 MPa, coal-rock combination is more prone to shear slip. The study is of significance for interface stability and fracture propogation in CBM recovery engineering through indirect fracturing.
- 1
Numerical Analysis and Engineering Practice on the Extraction of Continuous Large Rib PillarAbstract:
Taking the recovery of the special continuous large rib pillar in Wancheng Mine as engineering background, the feasibility of extracting the ore above 873m in the Wan-19 pillar by one-time lateral blasting was analyzed on the basis of fully evaluating the strength of the surrounding rocks by using numerical simulation technology combined with microseismic monitoring and on-site pillar cracking investigation. The research results show that: (1) The numerical simulation results are in good agreement with the field investigation results of pillar cracking, verifying the effectiveness of the physical and mechanical parameters and the reliability of the numerical model; (2) the arching effect of the surrounding rocks is very significant and the maximum principal stress with direction approximately parallel to the ore body strike also promotes the stability of the mined-out area. The mining of the Wan-19 pillar will not cause other pillars to be unstable. The deformation of the ground surface is between 0-2mm and the degree of subsidence is relatively small. Through engineering practice, about 60.2 thousand tons of ore are recovered successfully, which creates remarkable economic benefits for the company.
- 1
Based on the Data Decision Optimization Method of Backfill Cement MaterialsAbstract:
The cementious material is the key factor to determine the strength and economy of backfillmining.To solve the selection problem of cementing material for filling.Firstly, the technical performance of cementing agent is compared with the experimentaldata of filling material . Secondly，using the results of the experiment, when the age is fixed,the strength of the filling body and the amount of cementing agent are formed.The amount of cementing material used to meet the requirements of mining technology is calculated.The economic comparison of cementing agent is carried out.Finally，a comprehensive evaluation model of fuzzy mathematics and analytic hierarchy process are constructed, which is used for the choice of cementing agent. The comprehensive evaluation model of cementing material considers several factors,including technical performance, economic performance, safeguard ability.The qualitative and quantitative indexes are considered comprehensively,which provides technical ideas for the selection of backfill cement.
- 1
Research on development and application of steel slag-based cementitious powderAbstract:
Aiming at the high sludge tailings of Zhongguan iron mine, steel slag, slag and desulfurization gypsum solid waste resources were used to study the cementing material of steel slag-based filling and consolidation powder instead of cement.First to carry out the backfilling and active gelled material physical and chemical and particle size analysis, and then to carry out the steel slag powder base consolidation cementation filling body strength test, according to the orthogonal experiment is poor analysis and regression analysis, determine the best dosage of desulfurization gypsum, determine steel slag powder base filling consolidation optimized formula for steel slag powder 35%, desulfurization gypsum 18% and 47%;The strength of the tailings cemented backfill is about 1.5 times that of cement, and the material cost is only about 40% of the cost of 42.5 ordinary Portland cement.The industrial test results show that the compressive strength of cemented tailings backfill for 7d and 28d exceeds the design index of industrial backfill, and the consolidation powder of steel slag-based tailings backfill meets the mining requirements.
- 1
Practice of Step-induced Caving in High Stress Fractured PillarAbstract:
The 92 # ore body of Tongkeng Mine is mined by the waste field filling method and combined caving method after the empty field. Due to the untimely and incomplete treatment of the mined-out area, the reserved panel columns are chipped and roofed under the high level of stress. Become a fractured pillar of a hard-to-find island. This article uses 201 # line isolated island rupture panel column as a test stop. The rock integrity test is carried out to evaluate the stability of the bottom structure of the stope. The numerical simulation method is used to analyze the evolution law of the panel column and evaluate the induced fracture column. The feasibility of caving, and the use of the "partial empty field-induced caving method" combined mining to achieve the induced collapse of ruptured pillars. The test site depletion rate was reduced from 29.4% to 17.5%, and the loss rate was reduced from 43.8% to 26.3%. The good safety production effect provides a technical reference for the mining of other fractured pillars under similar mining conditions..
- 1
Constitutive model for rock mass considering initial joint damageAbstract:
To reflect the influence of rock mass structural characteristics and load effects on the rock mass damage and deformation failure characteristics, full considering the influence of joint initial damage, the multi-factor coupling damage model of jointed rock mass was established based on D-P criterion, and the theoretical expression of the model parameters was derived. The results showed that the damage evolution path corresponds to the evolution of mechanical properties and behaviors induced by changes in rock mass structure. Due to the existence of joints, the properties of rock mass showed obvious differences. When the dip angle is 0o and 90o, the initial damage value and critical damage value of rock mass are smaller, and the corresponding strength value is larger; When the dip angle is 60o, the initial damage value and critical damage value of rock mass are the largest, and the corresponding strength value is the smallest. The theoretical curve of the constitutive model was in good agreement with the experimental curve, which can describe the deformation and failure process of rock mass under different joint conditions.
- 1
Ecological Restoration and Slope Stability Analysis of Slag Discharge Site on The North Side of Yumen RiverAbstract:
In order to meet the requirements of ecological environment restoration and slag yard stability in the process of green mine construction, taking the slag discharge site treatment project on the north side of Yumen River as an example, aiming at the common problems of ecological environment and slope stability in coal mine, the ecological restoration and slope treatment measures of slag discharge yard are put forward. On the basis of theoretical analysis and qualitative calculation, the slope stability is quantitatively analyzed from the aspects of stress, strain and plastic deformation characteristics by using MIDAS-GTS-NX three-dimensional numerical simulation software. The study shows that the ecological restoration effect of the slag discharge yard on the north side of Yumen River is remarkable, and the slope is in a stable state after treatment; with the passage of time, the slope will produce small deformation under the action of dead weight and rainfall, and the effective plastic strain zone is concentrated in the gangue layer; the deformation mode of the whole structure of the slope is circular sliding, and the deformation area is mainly concentrated in the bottom two-grade slope, and the stability of the slope is improved under the action of retaining wall. It is suggested that the maintenance and monitoring should be strengthened in the later stage, and the slope support measures can be added in the lower two-grade slope if necessary.
- 1
Development of slag-based cementitious materials and study on strength and rheological properties of backfill taillingsAbstract:
In view of the high mud tailings filling aggregate in Zhongguan Iron Mine, the experimental study of slag based cementing material was carried out by utilizing industrial solid waste resources in Zhongguan area.Through the strength test of the cement of slag based cementitious material, the ratio of composite activator is 10% of clinker and 15% of desulfurization gypsum, and the ratio of the activator to slag powder is 1:3.Using the new cementitious material, the strength verification test of tailings cementitious body was carried out with two cementitious ratios of 1:4 and 1:8, respectively.The results show that the strength of the whole tailings cemented body with cementing ratio of 1:4 is greater than 2.5MPa in 28d, which meets the strength requirements of the backfill in one-step stope of Zhongguan Iron Mine.The cement body strength of the whole tailings with 1:8 cementitious sand ratio is greater than 1.5MPa, which can be used as the stoping filling cementitious material for the second step pillar mining with subsequent filling.Finally, according to the high mud tailings of Zhongguan Iron Mine, the tests on the strength of cemented backfill and the rheological properties of filling slurry with different cemented sand ratios and slurry concentrations were carried out, thus revealing the change rule of the strength of cemented backfill and the rheological properties of slurry, which laid a foundation for the application of new cemented materials in Zhongguan Iron Mine.
- 1
Research on floor failure and roadway stability affected by mining of near-distance extra-thick coalAbstract:
In order to study the stability of the floor roadway in the near-distance and extra-thick coal seam of Pingshuo Coal Mine, the floor deformation and failure laws under the influence of mining are discussed through theoretical analysis, numerical simulation and field measurement methods. The results showed that the theoretical calculation value of the failure depth of the working face floor was 18.4m, which is consistent with the measured results of the borehole peeping instrument. Numerical simulation results found that with the advancement of the working face, the floor damage depth and damage range of the working face gradually increased. When the working face advanced 200m, the maximum depth of floor damage caused by mining impact reached 16m, with peak stress and maximum concentration factor were 16MPa and 3.2, respectively. With the advancement of the working face, the deformation law of the approaching amounts of the two sides of the roadway and the roof and floor can be divided into three stages, including the slowly increasing section, the rapid increasing section, and the stable deformation stage. In the range of -100m~-50m, the deformation of the roadway was less affected by mining and increased slowly; in the range of -50m~50m, the deformation of the surrounding rock of the roadway was strongly affected by the mining, and the deformation increased sharply; in the range of 50m~100m, the deformation tends to be stable.
- 1
PREDICTION OF ROADWAY ROOF DEFORMATION BASED ON ELASTIC FOUNDATION BEAM THEORYAbstract:
In order to accurately predict the roof deformation of underground rectangular roadway. 3306 track tunnel of Daiyang coal mine is took as the engineering background. Based on Winkler foundation model, Kerr foundation model, beam bending theory and in-situ monitoring, the differences between the predicted and measured results of roof deformation under different elastic foundation models are studied. When Winkler foundation model or Kerr foundation model is adopted, the maximum displacement of roadway roof is 11.6 mm and 15.1 mm, respectively. Compared with the roof displacement based on Winkler foundation model, the prediction results based on Kerr foundation model are consistent with the measured results, and the average accuracy is improved by 18.26%. The maximum displacement of roadway roof decreases exponentially with the increase of elastic modulus of two sides surrounding rock, and increases exponentially with the increase of roadway height, and the influence of roadway height on roof deformation is greater than that of elastic modulus of two sides surrounding rock. However, Poisson"s ratio of two sides surrounding rock has no effect on roadway deformation. The application of Kerr foundation model can accurately predict the deformation of roadway roof, and the results can provide the basis for the reasonable roadway section and support design.
- 1
Study on optimization of stope structural with room-pillar methodAbstract:
In order to solve the problem of poor stability of deep goaf in a tungsten mine, based on numerical simulation, entropy weight method, BP neural network and chaos optimization algorithm, the structural parameters of deep stope were comprehensively studied, and a method of optimization of stope structural parameters was put forward. The results show that reasonable stope structural parameters are the key to ensure the stability of the goaf. The optimal stope structural parameters obtained by using this method are 4.8m width of edge pillar, 7.8m width of pillar in stope, 17m width of room, 9 pillars, which are the best parameters in the design range of stope structural parameters. Using these parameters can gain recovery rate of 79.80%. It provides a new idea for the optimization design of stope structure parameters.
- 1
Study on the Determination of the Limit Distance of Boundary Borehole Based on Blasting VibrationAbstract:
In the process of two-step mining and backfilling, the second-step stope will face the condition of filling body on both sides. Which results in the ore dilution and loss rate is difficult to be effectively controlled. In order to solve the problem in Ashele Copper Mine, the field blasting vibration effect test was designed based on the wave propagation rule of blasting vibration. The microseismic sensor was used to effectively collect the blasting wave of the stope, then the wave attenuation rule in the ore and the filling body was analyzed and studied. Combined with the detonation pressure theory, the limit distance of boundary borehole under the condition that the stope blasting does not affect the stability of the filling body on both sides was calculated. And the test stope was selected for industrial test. The result shows that the second-step test stope with optimized the distance of boundary borehole is successfully mining, after 3D laser scanning, there is no insufficient blasting of ore and large-scale overdigging of filling body on both sides of the test stope. And the dilution rate of the test stope is 5.94% while the loss rate is 3.99 %, which shows a good application effect.
- 1
Wedge Transition Open-pit and Underground Collaborative Mining Mode in Dagushan Iron MineAbstract:
In order to solve the problem of production capacity connection during the transition period from open-pit to underground, Dagushan iron mine is taken as the engineering background, and the wedge transition open-pit and underground collaborative mining mode is adopted to make up for the lack of open-pit production capacity during the transition period by underground mining hanging-wall ore. For this reason, the final limit of open pit mining is optimized, the distribution position of hanging-wall ore is determined, and the mining time and induced caving technology of hanging-wall ore are studied. On this basis, the open-pit and underground collaborative mining schemes of Xiaogushan and Dagushan mining area are designed respectively. The total production capacity of Xiaogushan and Dagushan mining area are about 6.2 million t/a and 9 million t/a in the transition period. The theoretical research and practice show that the wedge transition open-pit and underground collaborative mining mode can meet the production demand of Dagushan iron mine during the transition period and realize the stable production capacity transition.
- 1
Research on exhaust emission law of mine diesel LHD in high altitude environmentAbstract:
In the process of using diesel LHD in high altitude metal mines, there will be obvious phenomenon of insufficient diesel combustion and more harmful gases are emitted. In order to reduce the concentration of harmful gases emitted by LHD, reduce the impact on operators" health, and effectively improve the working environment, the emission law of diesel LHD in high altitude metal mines is studied Research. In this paper, km9106 type comprehensive flue gas analyzer was used to test the flue gas at 90 m, 150 m, 1524 m and 3740 m respectively The concentrations of CO, no and NOx in the exhaust gas of two types of mining diesel LHD in four underground metal mines at an altitude of 1.5 m were measured under idle and load conditions, and the variation laws of the concentrations of harmful gases in the exhaust gas of diesel LHD at different altitudes were analyzed. The test results show that the concentrations of CO, no and NOx in the LHD exhaust increase with the increase of altitude. The concentrations of CO, no and NOx in the LHD exhaust at 3740 m altitude are 825%, 261% and 117.4% higher than those at 90 m altitude at idle speed, respectively.
- 1
Experimental study of shear characteristics of rough rock joints under direct shear testsAbstract:
Three groups of joints with different roughness were casted by high strength gypsum material and a series of constant normal load shear test were carried out to study the influence of roughness and filling on the mechanical properties of jointed rock. The results show that the shear stress versus shear displacement curves can be divided into peak and gentle types caused by the influence of roughness and filling material; the peak shear stress of rock joints increased with the increase of roughness, and the filling material weakened the significance of roughness on shear strength; in terms of normal deformation, both the unfilled joints and the infilled joints with large roughness showe the type of compression-dilation, for the filled joints with small roughness, the dilatancy behavior is mainly controlled by the filling material and which shows the type of pure compression; joint failure type is not single, the shear failure process is a combination of slidding, cracking, and shear or tensile cutoff; through experimental analysis, the failure of rock-jointed mass was categorized into the slipping-cuttoff, cutoff-cracking, slipping between infill material and incompletely cutoff.
- 1
Influence of speed on dust transport law and simulation analysisAbstract:
From the production and transportation links of the open-pit mine, there is basically dust in any place of the mine. Due to the influence of a large number of dust distribution and climate factors, it is often accompanied by the generation of dust, which seriously interferes with the production activities of the open-pit mine and reduces its efficiency. In this study, with the help of Fluent software and the principle of gas-solid two-phase flow, a mathematical geometric model was established to study the dust transport characteristics of vehicles in the natural environment at different speeds. Studies have confirmed that when the speed reaches 15m/s and the wind speed is 3.5m/s, the dust concentration caused by it is about 78mg/m3, which is greater than 20mg/m3 emphasized by the national health department. Due to the increase of the vehicle speed, the dust is raised in a wider area and suspended for a longer time. The dust concentration is positively correlated with the vehicle speed. The dust concentration caused by the operation of the transport vehicle in the upwind environment is higher than that in the downwind environment. Based on this, the treatment method to deal with the open pit mine transport dust can be formulated more accurately.
- 1
Mechanical properties and energy evolution of sandstone under cyclic loadingAbstract:
Based on the cyclic loading and unloading test results, the characteristics of stress-strain curve, deformation characteristics and acoustic emission energy characteristics of sandstone are analyzed. The cyclic loading and unloading curve of sandstone forms a pointed hysteretic loop, and the hysteretic loop constantly migrates backwards.Under loading and unloading cycle, the peak strength of sandstone decreases compared with uniaxial compression and is negatively correlated with cyclic stress.According to the residual strain data uring the cyclic loading and unloading of sandstone, the variation law of the cumulative residual strain difference and the number of cycles was obtained.After exploring the characteristics of elastic modulus in loading and unloading stage, it is found that the elastic modulus in unloading stage is always larger than that in loading stage, and the elastic modulus is positively correlated with the cyclic stress.The variation of ae energy is regular under cyclic loading and unloading. The variation of energy is analyzed to obtain the characteristics of energy release at each stage of failure.
- 1
SHEAR RHEOLOGY DAMAGE MODEL OF WEAK INTERLAYER BASED ON FRACTIONAL CALCULUSAbstract:
The study of shear rheological mechanical properties of weak intercalation is of great significance to ensure the long-term stability of slope, and the establishment of constitutive model which can describe the shear rheological characteristics of weak interlayer is the key to the study. By analyzing the shear rheological test results of weak interlayer under different shear stress levels, the fractional calculus theory was introduced, and the Kelvin body in the traditional model was replaced by Abel clay pot element. From the perspective of probability theory and statistics, the Weibull probability density distribution function obeying the loading time t was further introduced, which can represent the statistical damage variable D of weak interlayer A non-linear fractional order shear rheological damage constitutive model was established, which can fully describe the three stages of attenuation, stability and acceleration. On this basis, according to the secondary development program interface provided by FLAC3D, the secondary development of damage constitutive model was realized by VC + + programming method, and the developed model was verified. The results show that the FLAC3D numerical test results based on the user-defined nonlinear fractional order shear rheological damage constitutive model were in good agreement with the laboratory shear rheological test results, indicating the applicability of the established model. The results can provide a reference for the long-term stability study of slope with weak interlayer.
- 1
Comprehensive Analysis of Slope Stability of a Large Open-pit MineAbstract:
The stability of slope has a significant impact on the mine construction and production. Taking the slope of a phosphate mine in Guizhou Province as the background, the 3D numerical model is created by Midas GTS numerical analysis software. The triangular network model (DXF file) constructed by 3DMine is combined with Midas GTS numerical analysis software to analyze the spatial geometric topology. Then the model is imported into FLAC3D for calculation and analysis, and the slope stability is evaluated by comparing the on-line monitoring results of on-site displacement, which reversely verifies the rationality of the selected physical and mechanical parameters and the accuracy of the analysis results.
- 1
Prevention and Control Technology of Group Goaf Collapse in Gypsum Mine Based on Shell-boundary TheoryAbstract:
Aiming at disaster of goaf collapse in gypsum mine, from blocking large area chaining collapse, designed prevention and control technology of group goaf collapse based on shell-boundary theory, which forming the first shell-boundary structure by strengthening pillar in mining unit, forming the second shell-boundary structure by strengthening isolated pillars between mining units, forming the third shell-boundary structure by strengthening isolated pillars among mining units. Taking a gypsum mine in Shandong Province as the engineering background, designing anchor bolt parameters of pillar in mining unit, bolt and building wall parameters of isolated pillar, and using anchor cable to forming a weaken plane to block transfer effect of fractured and movement of overlying strata. Maximum settlement of surface is 5.1cm, and application effect is well. The research could give important guidance and reference to prevent large area goaf collapse in gypsum mine.
- 1
CONTACTLESS MULTICHANNEL ONLINE PULP DENSITY DETECTION SYSTEM AND METHODAbstract:
In order to verify the accuracy, robustness and applicability of the pulp density on-line detection system, a comparative test between manual sampling data and on-line detection system data was carried out in the concentrator of Angang Group GUANBAOSHAN Mining Co., Ltd. In this test, the drying weighing method was used, the sampling barrel was used, the sampling was carried out at the secondary strong magnetic process nozzle position of the magnetic grinding workshop, and the drying measurement was carried out in the North Laboratory of the flotation workshop. Four samples were taken at each sampling point, and the average value was used to eliminate the sampling deviation. A total of 44 days of field sampling were carried out, and 88 groups of valid data were collected. Among all the data, 84 groups with deviation less than 1.5% accounted for 95.45%, and 4 groups with deviation greater than 1.5% accounted for 4.55%; the maximum deviation of online detection system was 3.49%, the minimum deviation was 0.01%, and the average deviation was 0.79%, standard deviation was 0.53%. The results show that the density online detection system has high precision and good real-time performance, which can completely replace the manual detection method to guide production.
- 1
Study on the effect of compound early strength agent on the early strength performance of large dosage fly ash cementAbstract:
For an equal amount of fly ash replacement in cement mine hole sealing material in cement base material problem such as the lack of early strength, setting time long, fluoride calcium aluminate, calcium hydroxide, three early strength agent triethanolamine blending of blended cement with high volume of fly-ash, from the early strength, fluidity and setting time study early strength agent on the early performance of OPC - FA and stimulate the active effect of fly ash.The results showed that when the mass ratio of C11·A7·CaF2 was 1.5%, the mass ratio of Ca(OH)2 was 0.5%, and the mass ratio of TEA was 0.02%, the early strength of the samples improved the highest, and the compressive strength of the samples on days 1,3,7,14,28 increased by 121.3%, 81.7%, 52.3%, 35.6%, 25.5%, respectively.According to XRD, SEM and TG-DTG analysis, the synergistic effect of the combination of C11·A7·CaF2, CH and TEA three early strength agents can effectively stimulate the activity of fly ash and accelerate the hydration reaction of slurry, resulting in the increase of the production of C-S-H colloid and ettringite, forming stable cementite aggregation.The hydration structure of OPC-FA sealing material is more stable, the pores are smaller, and the early strength is improved more.
- 1
Experimental Study on the Correlation between Local Bond-Slip Characteristics of Rock Bolt and Surrounding RockAbstract:
In order to explore the influence of surrounding rocks on the local bond-slip characteristics of bolts, two types of sandstone and steel tube anchors were tested by central pull-out test. The pull-out failure modes of anchors with different surrounding rock media, the load-displacement curves, the distribution characteristics of bond stress along the bolt and the influence mechanism of surrounding rock media on the local bond-slip characteristics were analyzed. The results show that: (1) the failure modes of rock bolt pull-out test are splitting failure and pull-out failure; (2) the anchorage force is positively correlated with the strength of surrounding rock, and the descending order is steel tube, black sandstone and yellow sandstone; (3) the load-displacement curve can be divided into four stages, and the slope of the first stage of the curve is related to the surrounding rock medium. The slip failure surface of the anchorage interface is formed at the end of the first stage, and the shape of the slip weak surface determines the subsequent development trend of the curve; (4) with the increase of pull-out load, the bond stress transits from uniform distribution along the interface to non-uniform distribution. The peak value of bond stress is located
- 1
Experimental Study on Beneficiation Process of A Sodium Amphibolite Type Low-grade Rare Earth-Iron Ore in Inner MongoliaAbstract:
Aiming at the problems of a rare earth-iron ore in Inner Mongolia that there are many types of minerals, the high content of F and S in the iron concentrate at the production site, and the low utilization rate of rare earths, classification and sorting according to the type of ore are carried out. Targeting sodium amphibolite-type low-grade rare earth-iron ore. The process flow of "stage grinding-stage separation and recovery of iron-tailings flotation and recovery of rare earths" was adopted for the beneficiation test. The results show that under the condition of first stage grinding fineness -0.074mm 91.03%, roughing magnetic field strength 135.32 KA/m, selected magnetic field strength 95.52 KA/m, second stage grinding fineness -0.045mm 90.56%, second stage magnetic field strength 95.52KA/m, an iron concentrate with TFe grade of 65.12% and iron recovery rate of 70.69% can be obtained. under the condition of flotation slurry concentration 40%, the flotation temperature 40℃, the amount of Na2CO3 1.8 Kg/t, the dosage of inhibitor water glass 2.0 Kg/t, the dosage of 2# oil 50 g/t, the dosage of collector C5 0.8 Kg/t, the closed-circuit test of one roughing, two beneficiation and one sweeping was carried out, and the REO grade was 56.37% and the recovery rate was 72.54%. The beneficiation process has obtained good experimental results ,which solves the problems of high impurity content in iron concentrate and low rare earth recovery rate.
- 1
Study on the Effect of Water-absorbing Resin SAP Compound Ferride on the Early Strength Performance of Coal Mine Sealing CementAbstract:
In view of the problems such as poor early strength, unstable condensation time and late failure of sealing holes in the complex working environment of coal mine cement, polymer absorbent resin (SAP) is introduced into the cement base, and the sub-nano-scale nickel-zinc ferride body is combined, and the material is XRD, electroscopic scanning (SEM), thermal weight (TG-DSC) and other microstructure analysis through mechanical performance tests such as pressure strength, flow and condensation time. The effect of SAP compound nickel-zinc ferrite on the early and strong performance of cement-based sealing materials for mineral use was studied. The experimental results show that when the mass fraction of 0.3% SAP and 1% nickel-zinc ferride are added, there is a good synergy between the two, and the improvement of the early and strong effect of cement sample is most significant, and the pressure strength of 1, 3, 7 and 28d reached 9.31 and 2 respectively. 4.63, 30.60, 42.82 Mpa, 39.60%, 29.56%, 26.78%, 29.69% higher than the blank group, and the condensation time was significantly shortened. According to microstructure analysis, the sub-nanomaterial nickel-zinc ferrite forms a tight high-energy particle structure under SAP particle ionization in the initial stage of hydration, which makes the cement interior more dense, the conversion of substances such as tricalcium aluminumate and tricalcium silicate to calcium hydroxide is accelerated, and the compounding of SAP and nickel-zinc ferrite effectively improves the early strength and self-conservation performance of the sample.
- 1
Industrial Application Research of Low Grade Mixed Siliceous PhosphoriteAbstract:
The low-grade mixed siliceous phosphorite has the characteristics of high SiO2 and medium MgO content, so it is difficult to be industrialized by single mineral processing. The process mineralogical analysis of the dissociation characteristics of the useful minerals and gangue minerals in the phosphate rock is carried out. Based on the actual production process of carbonate phosphate rock, through grinding fineness test and ore blending test, the selection fineness and ore blending method of this kind of phosphate rock are mainly investigated. The results show that: according to the SiO2-Mgo-P2O5 priority ore blending mode, the mixed ore blending of siliceous phosphorite and carbonate phosphorite is carried out under the conditions of raw ore w (SiO2) < 15%, w (MgO) 5.0% - 7.0%, w (P2O5) ≥ 21%, and the fineness w (- 0.074mm) ≥ 90%,and the reverse flotation was carried out .The indexes of phosphorus concentrate are as follows: concentrate yield 65.60%, w (P2O5) 28.67%, w (MgO) 1.01%, and P2O5 recovery 87.53%.
- 1
Study on Pore Structure and Damage Characteristics of In-situ Coal under Mining of Upper Protective LayerAbstract:
To study the pore structure and damage and failure characteristics of coal in situ under protective layer mining, taking Ji 15-31030 coal seam at the No. 12 mine of Pingdingshan Shenma Group as a case study, mercury intrusion experiments and computed tomography (CT) were carried out respectively on in-situ coal in the same direction of the protected layer. The results show that under the protective layer mining, the number of mesopores and macropores of coal samples affected by protective layer mining increases, the complexity of internal pore structure decreases, and the pore evolution shows an increasing trend from micropores and keyhole to mesopores and macropores, and the porosity of coal samples is increased by 59.23 % on average compared with that of coal samples without protective layer mining. In addition, the damage of coal samples affected by protective layer mining perpendicular to the joint direction and parallel to the joint direction is 95.26 % and 26.66 % higher than that of coal samples without protective layer mining, respectively. The research results provide data reference for revealing the mechanism of pressure relief and outburst prevention in protective layer mining.
- 1
Study on the Influence of Inlet Patterns for the Fixed-point Air Velocity Measurement Location in a Rectangular AirwayAbstract:
Taking 11219 return airway of Xiaojihan coal mine as an example, theoretical analysis, field measurement and numerical tests are conducted on the influence of inlet pattern for the fixed-point air velocity measurement location in a rectangular airway. The relationship between the friction resistance and the relative roughness of the airway wall is obtained through theoretical analysis, and the average relative roughness for the roof and two sides of the airway is determined to be 0.06 combined with the measured friction resistance. Numerical tests with five different inlet pattern models are carried out by taking the relative roughness as the boundary condition. The results show that the height in z direction of fixed-point air velocity measurement position tends to be the same when x is large enough. Taking the relative deviation between -0.1% to 0.1% as the comparison criterion, the inlet pattern model 2 can be arranged with sensor of fixed-point air velocity measurement after x=115m, the inlet pattern 1, 3 and 4 can be arranged with sensors after x=155m, and the inlet pattern model 5 can be arranged with sensor after x=185m for fixed-point air velocity monitoring. Taking the inlet pattern model 1 as an example, the fixed-point air velocity measurement location of the center of the center of airway width direction is z=2.695m, x>=155m.
- 1
Remote sensing monitoring of mining area based on image segmentation improved by channel attention and cost sensitivityAbstract:
In order to realize the remote sensing image segmentation of mining area to distinguish the change of mining area space-time environment, so as to achieve the purpose of remote sensing monitoring of mining area environment, a mining area environment monitoring model based on improved semantic segmentation is proposed. Firstly, u-net is used as the basic network of the semantic segmentation model. Secondly, in order to enhance the learning ability of the model for small targets, the cost sensitive weight vector method is used to improve the objective function during training, and the channel dependence of convolution feature graph is mined by channel attention model. Finally, the segmentation result of u-net is refined by conditional random field. Compared with the traditional algorithm, the improved algorithm greatly improves the edge segmentation accuracy of small targets in mining area environment to 81.6%, which is convenient to monitor the environmental changes of mining area more accurately from remote sensing images, such as house displacement, water body change, etc., and provides decision-making reference for safety construction and mining plan adjustment of mining area.
- 1
STUDY ON FAULT DIAGNOSIS OF DEEP SEA DRILLING RIG BATTERY SYSTEM BASED ON GK CLUSTERINGAbstract:
Deep sea drilling rig is an important equipment for offshore scientific investigation. To ensure its stable and reliable operation is a necessary prerequisite for the successful completion of scientific investigation tasks. The battery system of deep-sea drilling rig is an important power supply component of deep-sea drilling rig. In order to ensure that the battery system can continuously and stably supply power to the measurement and control system, this paper proposes a fault diagnosis method of deep-sea drilling rig battery system based on GK clustering. The experimental results show that the fault diagnosis accuracy of this method is 94.4%, which proves that the fault diagnosis method proposed in this paper has high fault diagnosis ability.
- 1
Research on Utilization of Low-grade Amphibole Iron Ore in Bayan Obo West MineAbstract:
In order to use the amphibole-type low-grade iron ore of Bayan Obo west mine, based on the study of ore properties, the magnetic roller speed, the particle size of discarding tailings, the number of discarding tailings segments, the fineness of grinding and other factors have been systematically investigated for dry tailings, The influence of rough grinding-weak magnetic separation and fine grinding-weak magnetic separation. The results show that the TFe content of the ore is 25.78%, and the iron element mainly occurs in the magnetite; through dry tailings, rough grinding-weak magnetic separation, fine grinding-weak magnetic separation processes, the TFe grade of 66.56%, TFe recovery rate of 48.54% and MFe recovery rate of 74.81% can be obtained. This research provides theoretical and practical reference for the utilization of low-grade amphibole iron ore in Bayan Obo west mine.
- 1
Study on the Effect of Sodium Chloride Solution on the Settlement of Bauxite Tailings MudAbstract:
Bauxite tailings mud contains a large number of fine particles and clay minerals, which makes it difficult to dewater and settle. The existence of salt solution will affect the interparticle force of clay minerals, and then affect its physical and chemical properties. In this paper, taking Guangxi bauxite tailings mud as an example, free sedimentation test and Zeta potential test were carried out with different concentrations of NaCl solution, and the microstructure of settled tailings mud was analyzed by SEM. The results show that with the increase of the concentration of NaCl solution, the flocculation rate of tailings mud decreases and the settling stable void ratio decreases. The absolute value of Zeta potential decreases with the increase of solution concentration, which reflects that the surface negative charge of clay mineral particles in slime is neutralized by Na+, which leads to the thinning of electric double layer and the weakening of electrostatic repulsion between particles. The arrangement structure of particles changes from edge-edge structure (EE) to face-face structure (FF), which results in the decrease of agglomeration diameter and slow flocculation rate. However, due to the change of the arrangement structure, a denser stack structure is formed between the particles, and the result of this analysis is consistent with that of SEM analysis.
- 1
The Influence of the Width of the Access Road and the Angle of the Side Hole on the Effect of Ore DrawingAbstract:
Sublevel caving method without pillar is widely used in domestic underground mine mining, and has the advantages of high mining efficiency and low cost, but the problem of large ore loss and dilution is particularly prominent. Through the analysis of multiple sets of access road widths, side hole angles and ore drawing experiments, the reasons for the changes of ore drawing indicators are explored on the ore dilution rate, ore recovery rate and combined with the development characteristics of the morphology of the released body. The results show that: ① Increasing the width of the access path and the side hole angle can significantly increase the recovery rate. The ore recovery rate increases by about 3.13 % for every 10° increase in the side hole angle; the ore recovery rate increases by about 0.82 % for every 0.5 m increase in the path width. When the road width is 5.5 m and the side hole angle is 55°, the ore recovery rate is the highest; ②The dilution rate first increases and then decreases with the increase of side hole angle and access road width. When the road width is 4 m, the side hole The dilution rate is the highest when the angle is 25°, and the width of the path has a significant effect on the dilution rate; ③The larger the width of the path and the side hole angle, the slower the growth rate of the morphology of the released body, the faster the development rate of the horizontal axis length, and the more The development speed of shaft length has little effect. The change in the shape of the released body leads to a decrease in the amount of waste rock at the top, and an increase in the amount of released ore, which affects the index of ore drawing. According to the influence characteristics of the width of the access road and the side hole angle on the effect of ore drawing, several suggestions are put forward for the actual mine production.
- 1
Study on optimization of rock drilling blasting parameters based on blasting funnel testAbstract:
In the deep part of Ashele, large-diameter deep-hole blasting is used to drop the ore. In order to improve the blasting quality of the stope, the blasting parameters suitable for deep ore bodies are studied. A series of single-hole blasting, wide-spacing blasting in the same segment, and inclined bench blasting funnel tests were carried out on the underground site. It was concluded that the best buried depth of the charge under the current mine rock conditions is 0.66 m; the best blasting funnel volume is 0.42 m3; The best explosive unit consumption is 0.37 kg/t; the reasonable range of the minimum resistance line is 3.19～3.60 m. According to the similar theory, the blasting parameters of the stope under the condition of deep large-diameter deep-hole blasting were analyzed and optimized. According to the optimized stope blasting parameters, on-site industrial tests were carried out. The stope boundary is intact, the ore size is uniform, and diluted The rate is 5.94%, the loss rate is 3.99%, and a good blasting effect has been achieved.
- 1
Experimental Research on Beneficiation of a Low-grade Copper-Zinc OreAbstract:
A low-grade copper-zinc sulfide ore has fine intercalation particle size, complex symbiosis relationship, high content of magnetite and pyrrhotite, the main purpose minerals are easy to select and difficult to separate, and the separation is difficult. The ore is separated by the process of "magnetic separation of iron removal-priority floatation of copper-zinc-sulfur mixed floatation-zinc-sulfur separation". Under the action of the new zinc inhibitor SJ, the efficient separation of copper and zinc is realized, and the laboratory closed circuit test A copper concentrate with a copper grade of 20.12%, a zinc content of 5.24%, and a copper recovery rate of 75.45%, and a zinc concentrate with a zinc grade of 53.68%, copper content of 0.96%, and zinc recovery rate of 78.97% were obtained. Development and utilization provided technical support.
- 1
Evolution Characteristics and Attenuation Model Construction of Limestone Compressive Strength under Ultra-low Temperature Freeze-thaw cyclesAbstract:
Lunar mining is a hot topic at present. To realize lunar mining, a series of basic mechanical problems such as the mechanical properties and evolutionary mechanism of lunar rocks under ultra-low temperature should be explored. In order to explore the evolution characteristics of the compressive strength of limestone under the ultra-low temperature freeze-thaw cycles, nuclear magnetic resonance, electron microscopy and uniaxial compressive strength test were used to analyze the changes of porosity, compressive strength and microstructure of limestone before and after thawing in the limestone with 0-12 freeze-thaw cycles at -100 ℃.The results show that :(1)with the increase of freeze-thaw cycles at ultra-low temperature, the compressive strength of rock decreases linearly with freeze-thaw cycles before thawing, and the compressive strength and porosity of rock decrease nonlinearly with freeze-thaw cycles after thawing. (2)The compressive strength of the rock before thawing is derived from the strength of the rock itself and the strength of ice, as well as the consolidation force generated by the bonding of ice as a binder with solid particles, making the compressive strength of the rock before thawing always greater than that after thawing. (3)The Mutluturk attenuation function model is accurate in characterizing the porosity variation characteristics of limestone under the ultra-low temperature freeze-thaw cycle, but it has a large error in compressive strength. Therefore, an improved model with a correlation coefficient of 0.9988 is proposed, which can more accurately represent the strength attenuation characteristics of limestone.
- 1
Experimental Research on Beneficiation of a Silver, Gold, Lead and Zinc Polymetallic Ore in HenanAbstract:
A flotation test was conducted on a silver-gold-lead-zinc sulfide mine in Henan. The selected grades of raw ore are Ag155.40g/t, Au 0.88g/t, Pb 1.54%, and Zn0.90%, using the "lead-zinc-sulfur" sequential flotation process. The closed-circuit test obtained the lead concentrate yield rate of 2.47%, containing Ag4681.64g/t, Au13.87g/t, Pb 57.51%, gold recovery rate 52.77%, silver recovery rate 88.53%, lead recovery rate 93.46%; zinc concentrate yield rate 1.93%, gold grade 5.15g/t, silver grade 197.64g/t, zinc grade 43.64%, gold recovery rate 15.31%, silver recovery rate 2.92%, zinc recovery rate 84.69%; sulfur concentrate yield rate 3.16, gold grade 4.89g /t, 142.64g/t silver grade, 23.80% gold recovery rate, 3.45% silver recovery rate.
- 1
Study on the influence of Resistance Line on the attenuation law of blasting seismic waveAbstract:
In this paper, based on the similarity theory, the similarity criterion for model test is deduced by dimensional analysis, and the concrete models with different resistance lines are established for single-hole blasting test, secondly, the attenuation of blasting seismic wave is analyzed from the energy point of view by using the HHT analysis method, and the energy attenuation of different resistance lines is obtained by comparing and analyzing the instantaneous energy spectrum of blasting vibration, it has certain guiding significance for reducing blasting vibration and improving energy utilization ratio.
- 1
Research on Optimization of Mining Method in JM Mine of Serbia Zijin Copper DooAbstract:
In order to solve the problem of insufficient mining capacity for low-grade porphyry copper mines that filling station have not yet been built, and to improve work efficiency and reduce mining costs, the engineering analogy method is adopted while making full use of existing projects and maintaining the overall status of mining unchanged. , Theoretical calculations, stope stability analysis and field test research. The mining method and stope structure have been optimized and improved, and the upward layered subsequent filling mining method has been adjusted to the upward phase subsequent filling mining method, which has received good applications. , The mining cost has been reduced by about 60%, the mining efficiency has been increased by 2 times, and the technical and economic benefits have achieved remarkable results, which can provide an effective reference for similar mines
- 1
Study on the Mechanical Properties of Interbedded Cemented Tailings Backfill under Different Curing AgesAbstract:
In order to explore the impact of different curing ages on the mechanical properties of the The layered cemented filling body under the curing age has been subjected to uniaxial compression test, and the stress-strain curve of the layered cemented filling body is obtained, and the peak strength, elastic modulus and strength reduction coefficient of the layered cemented filling body are analyzed. The results show that the layered cemented backfill has a similar stress-strain curve to the complete backfill, and the stress-strain curve at each curing age is divided into four stages, but there are obvious differences between different curing ages; The compressive strength and elastic modulus of the filling body increase with the increase of the curing age; the strength reduction coefficient of the layered cemented filling body under each curing age is less than 1, and the layered structure has a significant weakening effect on its strength With the extension of the curing time, the weakening effect is weakened. Therefore, an appropriate extension of the curing age will help reduce the stratification effect.
- 1
REVIEW SUGGESTION TO TECHNICAL PAPER EXPERIMENTAL STUDY ON THE CHARACTERISTICS OF FILLING MATERIAL ON FANKOU LEAD-ZINC MINEAbstract:
Aiming at the problems of low filling concentration, high production cost and insufficient tailings utilization rate in Fankou Lead-zinc Mine, this paper studied parameter model of high-concentration filling ratio of different filling materials and resistance characteristics with different conditions. The results show that the graded tailings can be selected as aggregate in the face of the stope, with a lime-sand ratio of 1: 4 and a mass concentration of 76%. The strength of the filling body meets R3≥3.0 Mpa, which meets the needs of the mechanized mining of the stope. Mixed tailings can be selected as the aggregate at the site. The lime-sand ratio is 1: 4, the mass concentration is 70%, and the strength of the filling body meets R28≥3.0 Mpa. With a 130 mm inner diameter pipeline and a flow rate of 60 m3/h, the transmission resistance coefficients of the graded tailings slurry and the mixed tailings slurry are 1.77 MPa/km and 1.97 MPa/km. Based on the existing filling pipe network system and pipeline parameters of the mine, when high-concentration filling is used, the filling line of the pipe network system is smaller than the slurry self-flow filling line, and both can achieve self-flow transportation.
- 1
Research on Truck Optimal Scheduling in Open Pit Mine Based on Artificial Fish Swarm Neural Network EvolutionAbstract:
For the sake of increasing the manufacture and conveyance productivity of open-pit mine, realize the effective retrieving of manufacture resources and low-cost work, a multi-objective open-pit lorry optimal scheduling technique based on neural network surrogate is advanced. According to the peculiarities of lorry manufacture and conveyance in open-pit mine, a multi-objective combinatorial optimization model is advanced with the objective of minimizing the lorry conveyance cost, minimizing the general waiting time of lorries, and minimizing the grade deviation rate of unloading station. Based on the basic artificial fish swarm algorithm, the neural network surrogate-assisted model is introduced to train the sample data to approximate the expected output and guide the population evolution, for make the search precision of the algorithm more exact and dependable and achieve the goal of speeding up the calculation speed of the algorithm. This paper takes the manufacture scheduling data of an open-pit mine in xiong'an New Area as the application object for emulation authenticate. The trial results prove that the artificial fish swarm algorithm based on neural network surrogate can solve the multi-objective lorry scheduling problem in open-pit mine, effectively enhance the working productivity of lorries in open-pit mine, debase the conveyance cost and cut down the grade deviation.
- 1
Research on Floor Heave Control Technology of Roadway in Daliuta Coal MineAbstract:
In the process of mining, the stability control of roadway surrounding rock is always one of the problems that need to be solved in high yield and efficient production of coal mine.In order to reduce the influence of roadway floor heave on mining face, the control technology of roadway floor heave in Daliuta Coal Mine is studied by combining theoretical analysis, numerical simulation and industrial test with the background of the project of the return air flow groove of No. 52303 working face in Daliuta Coal Mine.The results show that the main reasons for floor heave of 52303 working face are low strength of roadway floor, poor mechanical properties, and great disturbance influence of "one excavation and two mining". The type of floor heave of 52303 working face is determined to be water expansion type floor heave + extrusion flow type floor heave.Combined with the floor heave mechanism and practice, the control measure of "grouting reinforcement local control" is proposed. The engineering practice shows that the scheme can effectively control the floor heave of the roadway and ensure the stability of the roadway, which provides a feasible engineering reference for the similar roadway floor heave problem under the influence of mining.
- 1
Performance and application of VAE modified cement based grouting materialAbstract:
In order to improve the mechanical properties of cement-based grouting materials, the mechanical properties of ordinary portland cement were modified by VAE emulsion. The effect of VAE emulsion on the water cement ratio, mechanical properties and toughness of Portland cement was studied. The mechanism of modification was discussed and analyzed by SEM. The test results showed that the water cement ratio of composite grout showed a trend of first decrease and then increase with the increase of aggregate cement ratio. The addition of VAE emulsion increased the compressive strength of cement slurry slightly and increased the flexural strength greatly. When the amount of VAE emulsion was 3%, the modified effect of cement paste was the best; meanwhile, the VAE emulsion was added to improve the toughness of cement-based materials. The microstructure analysis shows that the VAE film and cement hydration products form an organic-inorganic interpenetrating three-dimensional network structure, which limits the spread of micro cracks in the stone body. The field test shows that the overall stability of coal wall is significantly improved by injecting composite slurry, and the problem of coal wall spalling is effectively solved.
- 1
Risk prediction of coal and gas outburst based on entropy weight-attribute mathematicsAbstract:
To accurately predict the risk of coal and natural gas emissions,a comprehensive model was developed to assess coal and natural gas emissions risk based on the critical value of the index and the number of brands,combined with entropy weight method and attribute mathematics theory.The results show that the coal failure type,coal Platts coefficient and gas pressure have the greatest influence on the coal and gas outburst in this working face.The prediction result of coal and gas outburst in the working face under the coupled model is general outburst risk,which is consistent with the dynamic phenomenon of gas on site.This model can provide a fast and feasible new method for predicting coal and gas outburst accurately.
- 1
Experimental study on thermal variation characteristics of surrounding rock thermal conductivity in deep minesAbstract:
The heat release of surrounding rock is one of the inducements for the deterioration of thermal environment in deep mines, and the thermal conductivity of surrounding rock is the key parameter to describe the heat transfer ability of surrounding rock. In a gold mine in zhaoyuan sample experiment study, through LFA457 laser thermal conductivity of the granite samples in 25 ℃ to 200 ℃ between coefficient of thermal conductivity was measured, and by using scanning electron microscopy (sem) further granite specimens with temperature change was analyzed by means of the microscopic damage condition, the experimental results show that when the temperature coefficient of thermal conductivity of granite sample would be reduced, the temperature from 25 ℃ up to 200 ℃ granite sample average coefficient of thermal conductivity fell to 2.811 from 3.658 W/m K W/m. K. This provides an experimental basis for the further study of the basic theory of heat release in deep mine surrounding rock and the prevention and control of underground heat damage.
- 1
Mechanical Behavior and Crushing Mechanism of Tailings Material under Triaxial CompressionAbstract:
In order to explore the mechanical behavior and crushing mechanism of tailings material under a high-stress state, triaxial compression tests with different confining pressure, water content, and dry density is carried out to analyze the influence of confining pressure, water content, and dry density on the degree of particle breakage. The concept of B_r^* is used to indicate the degree of particle breakage and the fractal dimension of particle crushing before and after tailing material tests is calculated in this paper. The connection between the fractal dimension and particle breakage rate is explored through these data. The test results reveal that the particle breakage has a good correlation with confining pressure and water content, while the dry density has little effect on particle breakage; There are two cutoff values of 1500kpa and 4000kpa in the process of particle crushing under high-stress state, which divides the degree of particle breakage into three different stages; there is a good linear relationship between B_r^* and D, and D can act as the characterization of B_r^*. The results of the study can provide a laboratory test basis for the high tailings pond.
- 1
Experimental Study on Flow Resistance and Rheological Parameters of Full Tailings in Longqiao Iron MineAbstract:
With the destruction of the original stress of the surrounding rock around the mining deposit of the underground mine resources, the integrity of the roof and surrounding rock of the empty area is destroyed, which affects the safety of the ground buildings. In order to ensure the safety of mine production and surface structures, full tailings filling mining is one of the effective methods to create a safe green mine. In the process of filling, high efficiency, safety and environmental protection are the preferred requirements of filling technology. in order to fill efficiently and safely, it is necessary to carry out experimental analysis of full tailings flow resistance and rheological parameters. In this paper, the rheological parameters and flow resistance are modeled and calculated by combining with Bingham rheological model. The equal volume reduction of the field filling equipment is experimentally analyzed. In the experiment, the flow resistance and rheological parameters are calculated and analyzed in two cases of full tailings without gelling agent and without gelling agent. the experimental data show that the yield shear stress is too large and the static friction force increases during pipeline transportation. in order to increase the rheological resistance. The rheological parameters and viscosity coefficientare related to the slurry concentration and the presence or absence of additives. It is proved by experiments that gelling agent needs to be added for filling. When the concentration exceeds 70%, the pipe diameter can not flow from 100 mm to 180 mm. When the concentration is 68%, the diameter of the pipe can flow from 100 mm to 130 mm, and when the concentration is 64%, the diameter of the pipe can flow from 100 mm to 180 mm.
- 1
Study on the Failure of Non-straight fractured rock based on XFEM under Direct Shear TestAbstract:
For exploring the influence of curvature and dip angle of S-type crack on the propagation law of rock crack under direct shear test, the initiation characteristics, propagation mode and stress state of rock crack were analyzed based on the theory of XFEM when curvature k = 0.1, 0.067, 0.05, 0.04, 0.025, 0.01 and dip angle θ = 0 °, 30 °, 60 ° and 90 °. The numerical results show that under the same curvature, S-type cracks all start as wing cracks in four dip angles, but when θ = 90 °, the cracks almost extend along the crack tip; Stress concentration is observed between rock cracks, and the concentration range is obviously affected by inclination angle and curvature; The crack initiation angle between S-type cracks and shear direction decreases with the increase of dip angle, but the crack initiation angle changes differently with the increase of curvature under the same dip angle.
- 1
Dynamic characteristics of gas flow field for the inflated airbag of a flexible air chamber jiggerAbstract:
The flexible air chamber jig has its unique advantages in large-scale applications, and it is gradually attracted the researchers’ attention. As a key component of flexible air chamber jig, the gas flow inside the airbag will directly affect its expansion and deformation, which will then has an important impact on the driving force of the rising water flow and pulsation of particles. In order to analyze the dynamic characteristics of gas flow field inside the airbag, the geometric model of airbag was established. Based on the grid division and the setting of boundary conditions, the dynamic characteristics of gas flow field during the expansion and deformation of airbag were studied by numerical method. The results show that the pressure and flow rate of gas inside the airbag are closely related to the hydrostatic pressure and the deformation of airbag. With the increase of intake time, the radial gas pressure and axial gas flow rate gradually become evenly distributed, and the gas flow rate on the inner wall around the airbag is lower. The symmetrical deformation that contributes to the expansion of the airbag provides a reliable guarantee for the stable pulsation of the water flow. As for a 2.5L airbag, the appropriate intake pressure and intake time is 30kpa and 0.23s, respectively. The research results will provide a theoretical basis for the analysis and design of the airbag, and it has great significance to ensure the safe operation of the flexible airbag and the stability of the jig water level.
- 1
Model test on anti washability of lake mud cement solidified slurry under the condition of mine hydrodynamic cavityAbstract:
The grouting of dynamic water cavity in mine is always a difficult point in curtain grouting. Aiming at the large cavity of dynamic water in the third stage curtain grouting in Chengmenshan, a kind of lake mud cement solidified slurry was developed, and the corresponding indoor simulation grouting test model was designed to study the diffusion law and water resistance of the slurry. The results show that the water resistance of the slurry is negatively correlated with the slump of the slurry and the flowing water velocity, and the water resistance of the slurry is better when the flowing water velocity is less than 1.5m/s.
- 1
Design and implementation of wireless intelligent spot inspection system for coal preparation equipmentAbstract:
Aiming at the problems of weak data processing ability and poor wireless signal of traditional coal preparation equipment, a wireless intelligent point inspection system of coal preparation equipment based on J2EE framework and B / s and C / S architecture is proposed. By using socket communication and c3p0 connection pool technology, the data parameters collected by the handheld point inspection instrument are automatically uploaded and stored in the MySQL database of the server. Using the isolated forest algorithm program to realize the automatic cleaning of interference data and the automatic uploading of normal data, the system response time is less than 500 ms. Through polynomial regression program and ecarts component, the data is visualized and analyzed on Android terminal of mobile phone and Web terminal of computer. Wireless AP bridge is applied to realize full coverage and no dead angle of signal in production workshop. The results show that the industrial operation effect of the system is good, the signal transmission power at the farthest distance of the workshop is up to 30 DBM, and the bandwidth is up to 60 Mbps. The system provides a new technical solution for standardization, informatization and intelligent spot inspection of coal preparation equipment.
- 1
Research on Downward Mechanization and Safe Mining Technology of Very Soft and Thin Broken VeinsAbstract:
In order to solve the problems of high labour intensity, low degree of mechanization and high production cost in the process of generally adopting downward approach cemented filling and mining of extremely soft and thin broken veins. Based on the actual situation in the southern ore belt of the Sen-gou mining area of Qian-he Gold Mine, the characteristics of the cemented filling mining with the downward approach of the extremely thin broken veins were studied, with the goal of improving the degree of mechanization and reducing the cost of mining, combined with similar related mine engineering practices, By optimizing the mining structure parameters, rock drilling and blasting methods, supporting technology and mining forms, and optimizing the applicable mechanical equipment, we have explored the technology of mechanized and safe mining of extremely soft and thin veins. Quasi-mining engineering, research on perturbation-free blasting and anchor-net support technology, using high-efficiency mining equipment to realize mechanized safe mining of extremely soft and thin veins. Field industrial tests show that this technology can realize mechanized and efficient mining of extremely soft and thin veins, and has good technical and economic indicators.
- 1
NUMERICAL SIMULATION ON THE BASIC RULES OF MULTI-HOLE LINEAR CO-DIRECTIONAL HYDRAULIC FRACTURE PROPAGATIONAbstract:
Directional rupture is one of the most important and common problems in rock breaking engineering. The purpose of directional rock breaking can be effectively realized by using multi-hole linear co-directional hydraulic fracturing. In this paper, the principle of the multi-hole linear co-directional hydraulic fracturing is analysed firstly. And then the RFPA2D-Flow software is used to verify the experimental results of multi-hole linear co-directional hydraulic fracturing. Finally, the basic rules of the hydraulic fracture initiation and propagation is studied. The following results are demonstrated: (1) RFPA software can be very helpful to study the basic rules of multi-hole linear co-directional hydraulic fracturing; (2) the process of multi-hole linear co-directional hydraulic fracturing can be divided into four stages: water injection boost, fracture initiation, stable fracture propagation and fracture connection. (3) The hydraulic fractures propagate along the direction of borehole distribution. The hydraulic fractures of different boreholes are influenced by each other, resulting in the connection of the hydraulic fractures.
- 1
Multi-source mine pressure prediction model analysis based on stacked-LSTMAbstract:
The roof accident caused by the unbalanced mine pressure is one of the major disasters in coal mines. The accurate prediction of the mine pressure is of great significance to ensure the safe mining of coal seams. In order to improve the prediction accuracy of mine pressure, a multi-source mine pressure prediction model based on stacked LSTM is proposed. First, the gray correlation degree is used to analyze and sort the multi-source pressure of the coal mining face and perform data preprocessing; secondly, the stacked network structure is used to determine the number of hidden nodes and the number of iterations of each LSTM layer. Finally, the Adam optimization algorithm is used to optimize the model and realize the prediction of the mine pressure at the working face. The root mean square error(RMSE) is used as an evaluation index to evaluate the performance of the prediction model. The experimental results show that: compared with the BP model, the stacked LSTM multi-source mine pressure prediction model reduces the RMSE on the training set and the test set by 49.15% and 51.26% respectively; Compared with LSTM, it is reduced by 45.37% and 46.61%; compared with GRU, it is reduced by 44.66% and 45.89%. Therefore, the established stacked LSTM multi-source mine pressure prediction model has higher accuracy in mine pressure prediction.
- 1
Convenient Calibration Method of Earth Pressure Cell Based on Similarity TestAbstract:
In order to obtain accurate data of earth pressure in similarity test, the cell needs to be calibrated before each use. For the problem of complicated calibration program of earth pressure cell, a convenient method using sand which can be applicated in most laboratories is designed by using uniaxial compression apparatus. Based on this method, 15 resistance strain cell are calibrated, and the σ-V curves are fitted. The results show that the correlation coefficient R2 of each group of test data is more than 0.99, the linear correlation is strong, and the test data are correct and reliable, which proves that this method can better calibrate the resistance strain earth pressure cell. The value k1 tested in sand is less than k2 given by the manufacturer, and the cell should be re-calibrated according to the specific environment before use. Then, aiming at the problem of coal-water conflict in the western mining area, the obtained calibration coefficient is applied to the similarity test of underground reservoir in coal mine, and the stress curve obtained is in good agreement with the actual situation. At the same time, it is found that there is a large stress concentration in roof groove area of the dam.
- 1
Study on Mechanical Characteristics and Damage of Coal and Rock Cutting by Conical PickAbstract:
The variety of cutting force and rock damage in the process of coal and rock breaking by pick play an important role in guiding tool design and improving coal and rock breaking efficiency. In this paper, ANSYS / LS-DYNA is used to establish the mechanical model of single pick crushing coal and rock. The simulations were carried out at the cutting depth of 2 mm, 4 mm, 6 mm, 8 mm, 10 mm and 12 mm, and the cutting speed of 0.5 m/s, 1 m/s, 2 m/s, and 3 m/s. The rock breaking process of the pick with a cutting depth of 6 mm was analyzed. The change process of the cutting force with time and the change process of the average cutting force with the cutting depth were analyzed. The damage range was quantified by the diameter of the damage area. The average cutting force of the maximum cutting depth of 12 mm is 21.6 kN larger than the minimum cutting depth of 2 mm, the diameter of damage area is 32 mm larger. The average cutting force of the maximum cutting speed of 3 m/s is 0.9 kN larger than the minimum cutting speed of 0.5 m/s, the diameter of damage area is 5 mm smaller. The results show that the cutting force first increases and then tends to be stable with the movement of the pick, and the average cutting force increases significantly with the increase of cutting depth. With the increase of cutting depth, the damage range first increases and then tends to be stable. The cutting speed has little influence on the cutting force and damage, and the smaller cutting speed is more conducive to reduce the cutting force and increase the damage range.
- 1
Study on Prevention and Control of Dynamic Disaster of Thick Rock Stratum in Coal Mine by Hydraulic Fracturing Technology in Surface Vertical WellAbstract:
Taking the high-level and extra-thick red bed sandstone above 63up06 working face of Dongtan coal mine as the research object, the FLAC3D numerical simulation software is used to research the rock fracture situation and energy evolution characteristics before and after hydraulic fracturing cutting high-level hard rock stratum. The results show that: after hydraulic fracturing, the weighting step distance of the initial break of extra-thick rock layer is reduced from 260m to 180m; after fracturing, the peak value of stress in front of the working face decreases continuously in the severe influence area of hydraulic fracturing, which is smaller than that before fracturing, and the stress concentration in front of the working face is weakened; the elastic energy within the rock layer is uniformly distributed, with no large-scale accumulation of elastic energy before the initial break of the high-level rock layer. It can be concluded that the hydraulic fracturing technology of surface vertical well can effectively slow down the stress concentration phenomenon in the excavation process, avoid the instantaneous release of energy in high-level strata, reduce the level of mine tremorand ensure the safety production of coal mine.
- 1
Study on Test and Evolution model of Stress Relaxation Rock BurstAbstract:
Aimed at the shortage of the research of hard rock stress relaxation characteristics and rock burst, uniaxial compression stress relaxation rock burst test about gabbro samples with rock burst tendencies was carried out, two kinds of stress relaxation rules and rock burst evolution processes were obtained, a stress relaxation model was established, the stress relaxation damage variable was defined, the mechanism of stress relaxation rock burst was analyzed. Results show that the process of stress relaxation rock burst can be divided into two types: In the first category, gabbro samples undergo three stages of evolution: rapid attenuation, gradual attenuation and stabilization. In this process, the specimen may have a slight to moderate local rock burst, which appears in the attenuation phase and finally tends to be stable; In the second category, gabbro samples undergo three stages of evolution: gradual decay, rapid decay and loss. In this kind of process, the whole process can be accompanied by a slight to moderate rock burst, and eventually a strong rock burst or a whole burst; The whole stress-relaxation rock burst has gone through the complex process of crack initiation, propagation, penetration, explosion opening, particle and rock fragment ejection until it finally burst; fractional calculus model can better reflect the first type of relaxation evolution stage. These two models are suitable for the prediction and analysis of minor to moderate rock burst in accordance with this stress relaxation rule but they cannot reflect the evolution stage of the second type of stress relaxation rock burst; On the basis of the definition of damage variable of stress relaxation, the first kind of process of the stress relaxation rock burst undergo three evolution stages: accelerated damage, slow damage and stable,the second type has gone through three evolution stages: slow damage, accelerated damage and unstable rock burst; The results of the study have good guidance and reference significance for the mechanism of rock burst, the prediction and warning of rock burst and the analysis of long-term stability of hard rock.
- 1
Experimental research on ash detection based on flotation tailings imageAbstract:
Aiming at the problem that it is difficult to realize the online detection of ash content of flotation tailings in actual production, a bypass image acquisition device was designed and built at the flotation site, and an ash detection experiment based on images of flotation tailings was carried out. According to the image characteristics, a GSA-SVR-based Ash prediction model. The results show that the mean gray value of the flotation tailing coal image and the mean values of RGB and ash are significantly positively correlated, the mean values of HS and ash are highly negatively correlated, and the mean values of H and S are not easily affected by light intensity fluctuations. The prediction model with image gray features and color features as model input variables has the best effect, the root mean square error RMSE is 1.828, and the coefficient of determination is 0.986. The ash detection method based on the image of flotation tailings is applied to the field ash detection. The average relative error of detection is 3.46% and the accuracy is 96.54%, which meets the requirements of ash detection. The research results provide a new idea for the detection of ash content of flotation tailings and a new basis for the development of intelligent flotation.
- 1
Study on the pore structure of filter cake based on micro-CT technologyAbstract:
Filtration dehydration is an indispensable process in the current mining industry. In this paper, the effect of particle size on the filtration rate was investigated through vacuum filtration experiments. X-ray micro-CT was used to obtain the microstructure details of the filter cake, and the influence of particle properties on the pore structure of the filter cake was analyzed and discussed. A series of key pore structure parameters such as distribution, connectivity, tortuosity, etc. were quantitatively characterized. The results show that when the average particle size increases from 10 μm to 60 μm, the filtration rate increases significantly. The particle size of the feed material can change the structure of the filter cake, which in turn affects the final filtration performance and permeability. Increasing the particle size will increase the porosity of the filter cake porous media, and increasing the porosity will increase the average diameter of the pores. Moreover, the widening of the pores will significantly reduce the capillary pressure in the porous medium, thereby increasing the filtration rate. When the particle size is finer, the pores in the filter cake are significantly narrower, the effective porosity is lower, and the path of fluid migration is significantly reduced, resulting in difficulty in filtration and dehydration. As the particle size increases, the tortuosity of the filter cake pores decreases significantly. The greater the tortuosity, the greater the resistance through the porous medium and the slower the filtration rate.
- 1
Research and application of articulated truck automatic fire extinguishing systemAbstract:
as the main transport equipment of open-pit mine, articulated truck will cause great economic loss in mine production once fire accident occurs. The articulated truck has high working intensity and many fire points, and its fire protection problem is becoming increasingly prominent. The fire mechanism of articulated truck is studied, and the traditional fire detection and judgment mode is broken. The intelligent fire detection method based on the cause of fire and multi information in the process is proposed. The fire monitoring method and the high-efficiency superfine dry powder fire-extinguishing scheme based on the articulated special environment are designed, so that the automatic fire-extinguishing system has higher sensitivity and accuracy.
- 1
Deep Sea Mining Vehicle Travel Speed Control Model DesignAbstract:
In order to determine the most suitable control algorithm for deep sea mining vehicle track speed control. Based on the hydraulic control model of deep-sea mining vehicles, a flow diagram of the control system for closed-loop speed control was developed. The signal response performance of different controllers was analyzed by comparing the Bode diagram control method, optimal control method, PID control method and adaptive fuzzy PID control method. The simulation results show that the adaptive fuzzy PID method is most suitable for the speed control of deep-sea mining vehicles, which not only solves the overshoot problem that other control algorithms cannot solve, but also can play a role in adjusting the desired speed output.
- 1
Determination and control of key parts of surrounding rock for rapid excavation in abnormal area of coal roadwayAbstract:
In order to solve the problem of serious deformation of the local area of the roadway ledge during the rapid excavation of the 150802 belt in the Liuzhuang Coal Mine, the key parts of the abnormal area of the roadway were determined by the FLAC3D numerical simulation software. The results showed that: a large shear was generated at the roadway ledge. In the stress concentration area, the shear stress concentration value of the high side angle is greater than that of the low side angle, and the displacement and deformation of the roadway roof is greater than the two sides. It is determined through numerical simulation that the first key part of the roadway support is the two shoulders of the roadway roof, followed by The top board, and finally two gangs. The process sequence of priority support is proposed for the abnormal area, and the “bolt with mesh cable” is adopted to strengthen the support plan for the surrounding rock of the roadway. The two shoulder sockets of the top plate> the top plate> the two sides are consistent with the numerical simulation results, and the maximum bolt stress value in the abnormal area is 66KN, which tends to be stable. After the 150802 belt along the roadway in Liuzhuang Coal Mine adopts the combination of "anchor belt and mesh cable" and gives priority to the support and plan for the abnormal area, after the roadway is driven 110m, the overall deformation of the roadway surrounding rock gradually stabilizes, and the two sides of the roadway move closer The amount and the subsidence of the roof are both less than 45mm, and the deformation of abnormal areas is effectively controlled; on this basis, the average daily footage of the roadway is 16.8m, and the implementation of the 150802 belt rapid tunneling technology in Liuzhuang Coal Mine.
- 1
Optimization of Blasting Parameters in Roadway Excavation Based on Fuzzy Hierarchy Analysis and BP Neural NetworkAbstract:
Roadway excavation blasting plays a very important role in underground metal mine production. Optimizing the blasting effect of roadway excavation plays a significant role in improving excavation efficiency and reducing blasting cost. Therefore, a complete evaluation model of blasting effect of mine roadway excavation is established by using fuzzy hierarchy analysis. With the help of this model, the blasting effect of roadway is evaluated reasonably and objectively. And the following conclusions are obtained: (1) A two-level fuzzy comprehensive evaluation index system for the blasting effect of roadway excavation in underground metal mines is established by using fuzzy hierarchy analytic; (2) The comprehensive scores of blasting effects in a mine are obtained by calculation; (3) The BP neural network is used to optimize the blasting parameters in reverse, which provides a new idea for the optimization of blasting parameters. Through the fuzzy hierarchy analytic to evaluate blasting effect and BP neural network to optimize blasting parameters can provide theoretical guidance for mine roadway blasting, which is of great significance for speeding up roadway excavation speed and optimizing blasting economic benefits.
- 1
STUDY ON CREEP CHARACTERISTICS OF ANTHRACITE UNDER DIFFERENT POROSITY AND PORE WATER PRESSUREAbstract:
The residual pillar immersed in Goaf water for a long time will produce creep instability. In order to study the effect of porosity and pore water pressure on the creep behavior of coal pillars, the pore-scale classification of anthracite samples was carried out by using three-dimensional CT scanning technique, the creep constitutive model of anthracite with different porosity was obtained by the UNIAXIAL creep tests of coal samples with different porosity. The creep law of anthracite under different porosity and pore water pressure was simulated by the numerical simulation software FLAC-3D, the results show that: (1) the samples with different porosity undergo four stages of transient deformation, decay creep, stable creep and accelerated creep; (2) with the increase of loading level, the instantaneous strain of the samples decreases gradually, (3) the axial strain increases with the increase of pore water pressure when the porosity is constant; (4) when the pore water pressure is the same, the smaller the porosity is, the smaller the deformation is; (5) with the increase of porosity and pore water pressure, the time of coal sample entering the accelerated creep stage is shorter.
- 1
Research on Application of Radar Monitoring and Early Warning Technology for Open-pit SlopeAbstract:
Combining the engineering geological conditions of the Wulagen lead-zinc mine and the existing condition of stope slope, a trailer-type synthetic aperture radar warning system was designed and established. Through the study of early warning principles and the setting of early warning thresholds, an early warning and forecast system for mine slopes was established. Through monitoring data processing and analysis, the radar system successfully sent the bedding slide of the slope in the +2284m~+2269m section near the exploration line 3 of the south slope of the mine on December 15, 2019 in the form of sound and light alarms, text messages, and emails. The yellow warning instruction avoided possible safety accidents in the mine, and at the same time proved the reliability of the slope warning threshold with displacement rate=30mm/d and continuous deformation body area=60m2. Finally, based on the retrospective analysis, the cause of this yellow warning was studied, which provided a basis for scientific and effective warning in the future.
- 1
Influence of different curing age on energy dissipation of cemented backfill with bentoniteAbstract:
in order to study the energy dissipation law of different curing ages on the backfilling mixed with bentonite, uniaxial compression tests were carried out in RMT-150C rock mechanics test system, and the data were processed according to the principle of energy dissipation. The results show that the strength of the backfilling mixed with bentonite has a positive correlation with the curing ages, and the strength first decreases and then increases with the increase of bentonite content, The results show that the energy storage limit and curing age follow the quadratic function y = a + bX1 + cX2, adding bentonite will reduce the energy storage limit; the energy consumption before peak is mainly elastic strain energy, and increases with the prolongation of curing age, but the proportion of total energy before peak decreases; the energy consumption rate of filling body is positively correlated with curing age, and the swelling rate is high The amount of bentonite has little effect on the energy consumption rate before the peak, and the energy dissipation rate in the deformation and failure stage before the peak is slightly higher than that after the peak.
- 1
The effect of local risk reduction of rock burst in hard rock based on different splitting angles of relief holesAbstract:
In order to solve the local hazard of rock burst,the FLAC3D numerical simulation was carried out based on the laboratory test and field.The results show that,under the same condition,the non-uniformity of surrounding rock deformation is the biggest around the pressure relief hole and the crack of zero degrees,and the energy is easily dissipated by local damage,the non-uniformity of surrounding rock deformation under the condition of cracks of 90 degrees and non-cracks is the smallest,almost uniform,and it is difficult to dissipate energy by local damage and fracture；When the crack angle is from 0 to 45,the plastic zone begins to sprout from the tip of crack tip and develops along the direction of maximum principal stress,the plastic zone from the face to the bottom of the hole shows an approximate cone-shaped contraction in the direction along the axis (y axis) of the pressure relief hole,that is,from the bottom of the hole to the face of the surrounding rock, the plastic zone increases continuously with the increase of the crack angle, the range of plastic zone of surrounding rock decrease accordingly；The stress relief hole perpendicular to the direction of maximum principal stress has the best effect to solve the danger；According to the fracture evolution of the surrounding rock surface in site,the integrity factor of the open face is determined comprehensively,and the depth of the relief hole in site construction is combined,the critical depth of pressure relief hole cracking can be roughly determined.
- 1
EFFECT OF COMPACTION ON STRENGTH AND IMPERMEABILITY OF TOTAL TAILINGS CONSOLIDATION BODYAbstract:
In order to solve the problem of the stability of total tailings consolidation body when it is discharged on the ground, compaction is proposed to enhance the stability of total tailings consolidation body.Is obtained under different compaction work of the backfilling consolidated body of maximum dry density and optimum moisture content, and on this basis, study the compaction work (598.2 kJ/m3, 1340.0 kJ/m3 and 1914.3 kJ/m3 and 2680.0 kJ/m3), dry density and moisture content (wop-4, wop-2, wop , wop+2, wop+4) and curing age (3d,7d and 28d) for consolidation unconfined compressive strength and the influence of permeability coefficient.The results show that the unconfined compressive strength increases with the increase of compaction work, dry density and curing age, and decreases with the increase of water content.The permeability coefficient increases with the increase of compaction work, dry density and curing age.The results show that the strength and impermeability of the total tailings consolidation body can be improved by compaction, and the stability of the total tailings consolidation body can be improved.
- 1
Research on optimization of stope structure parameters in veinlet zone of a tungsten mine based on FLAC3DAbstract:
In order to improve the stability of the stope in the veinlet zone of a tungsten mine, it can make normal mining. Taking the veinlet stope of the tungsten mine as the research object, the structural parameters of the stope were optimized, and the parameter schemes were designed based on the orthogonal test method, and the FLAC3D software was used for numerical simulation of each scheme, and the variation laws of stope stress, displacement and volume of plastic zone were comprehensively analyzed. The results show: the influence of pillar width on stope stability is more significant than that of top pillar thickness; the maximum tensile stress of top pillar monitoring point decreases with the increase of top pillar thickness. When the top pillar thickness is 8m, the tensile stress peak value exceeds the tensile strength of ore body; when the top pillar thickness remains unchanged, the maximum displacement of top and bottom plate decreases linearly with the increase of inter pillar width, and the volume of plastic zone decreases with the increase of pillar width; the optimal parameters of stope structure in veinlet zone are the top pillar thickness of 10m and the width of inter pillar of 12m.
- 1
Monitoring and analysis of excavation damaged zone in deep hard phosphate orebodyAbstract:
During the non-explosive mechanized mining in deep hard rock mines, the range of excavation damaged zone (EDZ) caused by high geostress and excavation disturbance affects the progress and efficiency of mechanized mining directly. In order to explore the distribution law of EDZ in deep hard rock phosphate orebody and provide design basis of cutting parameter for non-explosive mechanized mining, the monitoring test of EDZ was carried out in Kailin Maluping Mine. During the test, high-definition digital drilling television was used to shoot video images, and image analysis software was used to determine the thickness of the EDZ in the 18 monitoring holes that were regularly distributed on the test pillar, and then to obtain the contour of the EDZ. The test results show that the average thickness of the EDZ of the test pillar is 2.59 m, which can meet the requirements of non-explosive mechanized mining. Through artificial induction engineering, the range of EDZ can be enlarged, and the efficiency of mechanized mining can be improved. After the completion of ore mining in the EDZ, a new EDZ will emerge under the action of high geostress after a certain period of time, which is conducive to the continuous implementation of non-explosive mechanized mining.
- 1
PREDICTION MODEL OF SLOPE STABILITY OF OPEN PIT MINE BASED ON PCA-RVMAbstract:
Aim at the problems of low accuracy and low computational efficiency of traditional slope stability prediction model, an open pit slope stability prediction model combining principal component analysis (PCA) and correlation vector machine (RVM) was proposed. Principal component analysis was used to reduce the dimension of the variables affecting the slope stability, and four principal component variables were selected to establish the slope stability prediction model of open pit mine based on PCA-RVM. PCA-RVM model is applied to slope example, and compared with the RVM model and GEP model under the same sample, the results show that the safety coefficient value predicted by this model is obviously better than the other two models, and the prediction accuracy is higher and the dispersion is smaller, which provides a new way to accurately predict the slope stability of open-pit mine.
- 1
Experimental study on directional cracking of pre-grooved rock mass under true triaxial stressAbstract:
Aiming at the problem that the coal roof is hard and difficult to collapse, a pre-groove directional fracturing plan is proposed and experimental research is carried out, a self-developed large-scale true triaxial fracturing seepage simulation device was used to conduct physical simulation experiments to study the influence of different angles of pre-grooves (α) and different fracturing media on the initiation and propagation of fractures, the results show that: ①When the pre-grooves at different angles increase from 30° to 90°, the cracks start from the tip and gradually deflect to the maximum horizontal principal stress, and the crack initiation pressure gradually decreases, and the length of the cracks shorten; When fracturing the medium, the deflection cracks produced on the surface of the specimen are relatively tortuous, the initiation pressure is low, and the specimen failure takes a long time. When clean water is used as a fracturing medium, there are obvious smooth cracks on the surface of the specimen, the initiation pressure is high but the specimen failure time is short; ④The length pressure crack curve and the pressure deflection angle curve are obtained by fitting the experimental data, and it can be known that α During the change from 30° to 90°, the crack initiation pressure is decreasing, and the crack length and deflection angle decrease. When the prefabrication angle changes, the fitting curve can be approximated to calculate that the initiation pressure of the specimen and the crack length and deflection angle have certain reference value.
- 1
Design of key parameters of longwall roadway cemented filling faceAbstract:
In view of the difficulties in the recovery of pressed coal in the old urban area of a coal mine in Henan Province, the application of longwall cemented filling in roadway by roadway cemented filling is proposed to recover the occupied resources in the old urban area. In this paper, the interaction state of coal seam and filling body in the filling face in the first, middle and last three filling periods is analyzed, and three key parameters of cemented filling coal mining technology are put forward. the stress distribution and surrounding rock deformation characteristics of the filling face are studied by means of theoretical analysis and numerical simulation, and the roof subsidence deflection curve is obtained by establishing the roof control mechanical model of the filling process coal seam-filling body on the basis of numerical simulation. The study shows that the width of longwall cemented filling coal roadway is 5 m, the distance is 3 times the width of driving roadway, and the filling rate is 90%, which can effectively avoid the stress increase area of the previous roadway excavation, and the final subsidence displacement of the roof is 0.281 m, which plays a good role in controlling the roof deformation.
- 1
Simulation study on optimization of stope structure parameters based on CRITIC weighting methodAbstract:
In order to optimize the design scheme of stope structure parameters, this paper establishes a comprehensive evaluation index system with stress, displacement and technical and economic indexes based on the CRITIC weighting method. Using 3D Mine and MIDAS/ GMS-FLAC3D software, the maximum principal stress, minimum principal stress and displacement of goaf under different scale design schemes of pillar width, stope span and stope section height were simulated numerically, and the numerical simulation results were analyzed. Based on the CRITIC weighting comprehensive evaluation model, comprehensive evaluation of the design schemes of different stope structure parameter scales is carried out. Results show that the design of different scales of ore in the influence of the stress and displacement has obvious, design of different scales of maximum principal stress and minimum principal stress changing with structural parameters of stope scales showed a trend of fluctuations, is gradually increasing with displacement increases with stope structure parameters of the scale, comprehensive evaluation determine the optimal stope structure parameters design scheme is: the pillar width is 7 m, 7 m stope span and stope sublevel height 10 m.
- 1
Information Perception and Intelligent Warning for High Stress Surrounding Rock DisasterAbstract:
Aiming at the difficulties of online monitoring of surrounding rock stress and weak disaster warning capabilities of coal mine,the self-designed wireless sensor and wireless gateway for surrounding rock stress based on the LoRa protocol were designed independently to realize the capture and data transmission of underground surrounding rock stress disaster information. On the basis of real-time monitoring data of surrounding rock stress,a deep recurrent neural network surrounding rock disaster warning model using adaptive moment estimation optimization algorithm(Adam-DRNN) was proposed,and a system of information perception and intelligent warning for high stress surrounding rock disaster was constructed. The experimental results show that the Adam-DRNN warning model has high accuracy and strong generalization. Compared with the BP neural network warning model,the support vector regression warning model and the autoregressive integrated moving average warning model,the accuracy is increased by 23.1%,2% and 6.1% respectively. The system of information perception and intelligent warning for high stress surrounding rock disaster realizes real-time monitoring and intelligent warning of mine pressure on working face and tunnel area,improves the level of mine safety production management,and has good practical value.
- 1
Computer vision detection method for spontaneous combustion of coal stockpilesAbstract:
In the process of long-term coal storage in coal yard, the spontaneous combustion of coal pile will cause huge economic losses. According to the characteristics of smoke generated in the initial stage of coal spontaneous combustion, this paper proposes a detection method of coal pile spontaneous combustion based on video image. Through preprocessing the video image of coal storage yard to improve the image quality, combined with differential image and color filtering rules, a novel algorithm for suspected smoke area detection is proposed. LBP texture features and hog gradient features of suspected areas are further extracted, and support vector machine is used to comprehensively determine the spontaneous combustion smoke. The experimental results show that the detection accuracy of this method can reach more than 95.0%, which can effectively detect the spontaneous combustion of coal pile, and then improve the ability of fire warning in coal storage yard.
- 1
Research on Fuel Consumption Prediction of Truck in Open-Pit Mine Based on PSOGA-SVMAbstract:
Aiming at the problem of fuel consumption prediction of open-pit truck, an improved particle swarm optimization (PSO) algorithm based on genetic algorithm (GA) is proposed to optimize the parameters of support vector machine (SVM). The fuel consumption prediction model of open-pit truck which is based on PSOGA-SVM is constructed. The model in this paper considers 8 influencing factors such as transportation volume, transportation distance, road quality and weather, and selects truck fuel consumption data collected in a intelligent production control system of a large open-pit mine for experiments.This research also applies the model to actual mine scenes.It is obvious that the truck fuel consumption prediction model based on the PSOGA-SVM can predict truck fuel consumption data relatively quickly and accurately in the experiment. Compared with other experimental models, the prediction accuracy and stability of the model are improved by 30% and 34% respectively. The model is used in the prediction of truck fuel consumption in open-pit mines. It has good adaptability and can provide references for truck fuel consumption assessment and oil depot management in open-pit mines.
- 1
Simulation Analysis of Heavy Metal Cu2+ Migration in Large Tailings Ponds under the Coupling Action of Rainfall-evaporation-transpiration and GroundwaterHou Yongli, chenhongdan, 郝喆, 张颖
Abstract:
In this paper, the coupling effect of rainfall-evaporation-transpiration and groundwater is considered. Taking the Waitou Mountain Iron ore tailings reservoirs of Bengang Group as an example, the SEEP/W, VADOSE/W and CTRAN/W modules in Geostudio software are used to simulate the groundwater seepage characteristics of the tailings pond and the migration rule of heavy metal pollutants under the effect of rainfall-evaporation-transpiration. The results show that the vertical profile pore water pressure of tailings pond decreases along the direction close to the slope surface, and the pore water pressure of deep soil is not affected by rainfall-evaporation-transpiration basically. Rainfall-evaporation-transpiration interfere with the migration of heavy metal pollutants. The heavy metal pollutant Cu2+ migrates along the direction of the initial dam within 0~1095 d, and the concentration of heavy metal Cu2+ increases with time. Considering rainstorm-evaporation-transpiration, the total displacement and average velocity of heavy metal pollutants within 1095 d were increased to a certain extent. The results of this study provide a basis for environmental geological evaluation and pollution prediction and prevention of large tailings ponds.
- 1
Stability Evaluation of Typical Rock Slope in Sichuan under The Influence of Multiple Parameters and IndexesAbstract:
In view of the key problems of the uncertainty method in the evaluation of the rock slope stability, such as the index weight and the classification of membership degree, an evaluation model based on the improved entropy weight fuzzy evaluation principle is proposed. Through the establishment of the evaluation system of 12 influence indexes covering the slope geometry, geophysical and mechanical properties, rock strata and structural surface influence, hydrological and meteorological conditions, and external factors, the stability evaluation classification standard is established, and the stability rating of 9 typical open-pit mine slopes in Sichuan area is carried out. The results show that external disturbance, annual average rainfall and cohesion play a leading role in slope stability evaluation, with a weight of 34.92%, and the minimum impact of bulk density index is only 3.5%. The improved entropy weight-fuzzy evaluation model can not only be used as a supplement to the principle of maximum membership, but also can be used to rank slopes at the same level, and provide a reference and basis for the rational evaluation of slope stability.
- 1
Effect of pore evolution on adsorption and desorption characteristics of coal under the action of liquid nitrogenAbstract:
In order to study the pore evolution of coal under the action of liquid nitrogen and the influence of treatment times of liquid nitrogen on the adsorption and desorption characteristics of methane, the mercury intrusion experiments and a series of adsorption and desorption experiments were carried out on Yangquan anthracite coal in Shanxi Province. The results show that: 1) after 4 times of liquid nitrogen treatment, the number of pores in different sizes of coal sample increases in varying degrees, among which the liquid nitrogen treatment contributes the most to the increase of the number of macropores, and the cracking and permeability enhancement caused by liquid nitrogen can be attributed to three reasons: pore connectivity, pore fracture expansion and pore fissure proliferation; 2) with the increase of liquid nitrogen treatment times, the effect of liquid nitrogen treatment on the final adsorption capacity of methane was weakened continuously. In addition, the Freundlich formula can better describe the isothermal adsorption of methane at low adsorption pressure; 3) the improved lagergren adsorption kinetic formula can describe the change of adsorption capacity with time more accurately, and the time effect of coal adsorbed gas is almost not affected by liquid nitrogen treatment times. In addition, the freeze-thaw damage of coal can promote the desorption and diffusion of methane in coal. After 4 times of liquid nitrogen treatment, the desorption yield was the best. This study provides a certain theoretical basis for in-situ liquid nitrogen fracturing modification and increasing coalbed methane production technology.
- 1
Prediction of coal and gas outburst hazard zone based on GISAbstract:
This paper takes a mine in Guizhou as the research object,useing GIS technology and Kriging algorithm as research tools.Studying the coal seam of the mine gas outburst danger area on prediction analysis,divides the dangerous level area will finally,comparing the field measured results and hazard level of research,Research that:using VS2012 and.NET4.5.1 with ArcGIS Engine 10.2 c # development model of mine gas geology platform,solution the geological structure conditions and highlight the dangerous area of coal seam under forecast.Using Kriging algorithm to predict and analyze the gas content and coal and gas outburst risk area,the EM algorithm was used to fill the missing data,and the matter element analysis method was used to obtain 4 level I points, 8 level II points and 147 level III points in the data set.It is proved that in the study and analysis of coal seam gas outburst risk area,the visualization effect is the best when using common Kriging algorithm to improve the prediction accuracy of coal seam gas outburst risk area.
- 1
PREPARATION OF CALCINATION COMBINED WITH SODIUM CARBONATE MODIFIED TAIL COAL BASED ADSORBENT AND ITS ADSORPTION FOR CU (II)Abstract:
The development of tail coal based adsorbent can not only reduce the treatment cost of heavy metal ion wastewater, but also solve the environmental and ecological problems caused by tailing coal accumulation, and realize the high value-added utilization of tail coal. In this paper, a series of tail coal based adsorbents were prepared from flotation tailings (TC) by calcination in N2 atmosphere combined with sodium carbonate modification. The adsorption properties of various tailing coal adsorbents for Cu2+ were studied, and their structures were characterized by XRD, FTIR and SEM. The results show that: When the calcination temperature and calcination time were 800℃ and 1 h respectively, the concentration of Na2CO3 solution was 1.0 mol/L, and the modification time of Na2CO3 solution was 2 h, the CNTC adsorbent produced had the best Cu2+ removal effect in water. When the dosage of CNTC is 3 g/L and the adsorption time is 4 h at 25℃, the removal rate of Cu2+ in wastewater with initial concentration of 50 mg/L can reach 99.8%; The adsorption of Cu2+ mainly includes physical adsorption, ion exchange between Na+ and Cu2+, and chemical adsorption of oxygen-containing functional group -OH, Si-O and Cu2+.
- 1
Study on strength of backfill cemented with limestone powderAbstract:
In order to reveal the influence of the amount of limestone powder, the amount of cementitious material and the mass concentration on the strength of cementitious backfill, the calculation model of the strength of the backfill with limestone powder is established. First by physical and chemical test analysis of limestone powder and waste rock meet the aggregate using standard, and according to the grading test of waste rock and limestone powder uneven coefficient and curvature coefficient, in combination with standard by a non-uniform coefficient the waste soil mechanics strength with the lack of fine aggregate, vulnerable to compaction, porosity is larger, the impact strength of filling body. Therefore, strength tests of backfill at 3d, 7d and 28d with different amounts of limestone powder, cementitious materials and mass concentrations were carried out to determine that the relationship between each influencing factor and strength was positively correlated through variance analysis. Increasing the amount of limestone powder could effectively improve the strength of backfill at different ages. Finally, based on the unitary nonlinear theory, the SPSS curve was used to estimate the strength of backfill of each age to establish the multivariate nonlinear model. The average absolute error of each age calculation model was verified to be 0.0389, 0.0575 and 0.18. The prediction accuracy of the model was relatively high, which had certain guiding significance for the industrial application of limestone powder.
- 1
Improved genetic algorithm to optimize the car drive system since the immunity controlAbstract:
In view of the complex terrain changes of mine vehicles, the vehicles are vulnerable to impact and vibration in the process of driving, resulting in violent fluctuation of hydraulic control system and decline of stability. An active disturbance rejection control (ADRC) control method based on improved genetic algorithm is proposed. Firstly, the mathematical model of variable displacement pump controlled motor drive system is established by analyzing the working principle of hydraulic drive system of mine car. Secondly, the active disturbance rejection controller is designed for the purpose of stable speed control of tramcar. Combining with the idea of simulated annealing, the genetic algorithm is improved and further improved The parameters of auto disturbance rejection controller (ga-adrc) are optimized by improved genetic algorithm. Finally, the co simulation model of tramcar and hydraulic drive system is built in MATLAB, and the speed control performance and anti disturbance ability are simulated and compared by ADRC and improved ga-adrc. The simulation results show that the improved ga-adrc control method has high speed control accuracy and strong anti-interference ability, which is helpful to greatly improve the stability and robustness of the hydraulic control system.
- 1
Research on Simulation of Potential Debris Flow Occurrence Mechanism and RisingHeight in Huangshan Mining AreaAbstract:
A large amount of clay accumulated in the high gully in the Huangshan limestone open-pit mining area of Sichuan is easily induced by debris flow due to mining stripping, to analyze the probability of debris flow disasters to produce, the regional potential debris flow formation conditions and mechanism are studied, and design the optimal preventive measures, after the debris flow is triggered, the height of the rushing down to the bottom of the slope and rebounding from the bottom is calculated, and the particle flow software PFC is used for numerical simulation and verification. The results show that: The high-level gully in the mining area have three basic conditions for the formation of potential debris flow disasters: source, topography and water source, and mine debris flow disasters are very likely to occur; the soil in the gully is gradually saturated during the infiltration process of rainfall, and the internal friction angle and cohesive force continue to decrease until it loses balance, slides down the slope and mixes with water to form a debris flow; according to the calculation and prediction based on the empirical formula, the uplift height of debris flow after rushing down to the bottom of the slope and rebounding from the bottom is 29.5 m, which is in good agreement with the simulation results of particle flow. It provides an important reference for the design of debris flow protection and control measures.
- 1
Three dimensional numerical simulation of dam break of Xiaoxigou tailings pond based on SPH methodAbstract:
In this paper,the theory of Smoothed Particle Hydrodynamics (SPH) based on Herschel Bulkley model is used to numerically simulate the three-dimensional dam break of Xiaoxigou tailings pond. As fully considering the fluid like Shear viscosity behavior of tailings, establishing a calculation model which based on the form of breach obtained from physical model test, and obtaining dynamic features of dam break tailings evolution and spatial accumulation characteristics by simulation. Hence, the influence range of tailings dam break on downstream is determined, and the energy dissipation effect of buildings and structures on tailings flow is compared and analyzed. Also, according to the movement characteristics of tailings, we can classify and delineate the scope of risk prevention and control, formulate targeted measures for risk prevention and control, and reducing dam break risk of tailings pond.
- 1
Research on reasonable spacing of small interval deep-buried tunnel based on coupled continuous-discrete methodAbstract:
The size of tunnel spacing is very important for the stability of small spacing deep buried tunnel. Based on the continuous discrete coupling method, relying on the actual project of an iron mine in East China, the reasonable tunnel spacing is determined by analyzing the influence of excavation of adjacent tunnels with small spacing. The results show that: when the space between two tunnels is less than 0.67 times of the width of the tunnel (i.e. 4m), the tensile shear failure of the intermediate rock pillar occurs, which results in the tunnel instability; when the tunnel spacing is greater than or equal to 0.67 times the width of the tunnel, the deformation and damage degree of the surrounding rock are within the safe range, that is, the tunnel spacing above 4 m can ensure the stability of the tunnel and rock pillar, which is consistent with the actual situation on site. The research results have certain guiding significance for disaster prevention of deep buried mine engineering.
- 1
Study on the effect and mechanism of kaolinite on coal slurry dewateringAbstract:
The existence of clay minerals brings great challenges to the solid-liquid separation of coal slurry. It is necessary to explore the influence mechanism of clay minerals on coal slurry dewatering. In this paper, the influence of kaolinite on the dewatering effect of coal slurry was analyzed through vacuum filtration test, wetting heat measurement, SEM analysis, zeta potential and nuclear magnetic resonance test. The results showed that kaolinite had a great influence on the filtration and dewatering of coal slurry. After adding kaolinite, the filtration rate of coal slurry decreased, and the moisture and specific resistance of the filter cake increased. The wetting heat of coal was 0.389 J/g, while the kaolinite was 1.819 J/g, which suggested that the hydrophilicity of kaolinite was much higher than coal. The results of particle size analysis, SEM and zeta potential analysis indicated that kaolinite covered the surface of coal particles, thereby reducing the hydrophobicity of coal particles. NMR results showed that, compared with coal, the water relaxation time of the kaolinite filter cake was shorter, indicating that the pore size of the filter cake was smaller and the filter cake structure was denser. Therefore, the binding degree of water molecules was greater, which was not conducive to the removal of water.
- 1
Study on the Influence of Montmorillonite Content on Crack Closing in N2 Laterite AquicludeAbstract:
Clay mineral is the primary factor affecting the crack closing of laterite aquiclude. Montmorillonite is the main component of laterite clay minerals, and its content change is of great significance to the study of crack closing. Taking the overlying N2 laterite aquiclude on the 102 working surface of a mine in Yulin mining area as the research object, the influence of montmorillonite content on the crack closing of laterite aquiclude was explored by theoretical analysis and theoretical calculation combined with laboratory tests (XRD, expansive and closing tests and similar simulation experiments). The experimental results show that: 1) The clay mineral content in N2 laterite is 19.8%~32.7%, and the montmorillonite content accounts for 38.1%~56.4% of clay minerals in laterite. The expansion of montmorillonite is the root cause of crack closing. 2) When the ratio of montmorillonite content to the total amount of laterite minerals increases from 7.3 % to 12.3 %, the expansion rate increases from 10.97% to 15.31%, and the closing rate increases from 26.65% to 33.2%. The closing ability of laterite increases with the increase of montmorillonite content. 3) The crack closing law of red soil layer was verified by similar simulation test.
- 1
Study on the correlation between rock and rock mass propertiesAbstract:
In order to study the correlation between rock properties and rock mass properties, rock and rock mass tests are carried out in Yangquan coal area.The correlation between rock strength and rock mass strength, rock wave velocity and rock mass wave velocity is studied.The results show that the uniaxial compressive strength of rock has a similar trend to that of rock mass, and has a significant linear relationship.The fitted formula can be used to accurately convert the compressive strength of rock mass to the strength of rock mass.The wave velocity of rock is greater than that of rock mass.The relation between rock mass wave velocity and rock wave velocity is expressed by the proportional coefficient , and it is found that the proportional coefficient of different rocks is not the same and has great difference.This phenomenon is related to the integrity of the rock mass.The closer the wave velocity of rock mass is to that of rock mass, the more complete the rock mass is.
- 1
The study of a new mining method at Jinchuan Longso mineAbstract:
Jinchuan Dragon"s first mine is a high-stress crushing ore body, and because of year-on-year excavation, resulting in a decline in taste, resulting in engineering and economic benefits in the excavation operation difficulties. In order to promote the Dragon"s first mine to achieve the maximum balance of mining and economic benefits, in the area of support difficulties to the hexa-shaped road glue filling mining method, layer by layer, stable structure effectively avoid stress at the edge of the empty area concentration, this paper also draws on the opinions of many experts and scholars, seeking to adopt the way of electro-tunnel mining at a specific level, with a view to better mining effect and good economic benefits.
- 1
MINING TECHNOLOGY AND STOPE STABILITYANALYSIS OF DADONG GOLD MINEAbstract:
In this paper, taking the steeply inclined extremely thin ore body with elevation above + 65m in Dadong gold mine as the research object, through rock mechanics test, analysis of rock engineering geological conditions and rock mass quality evaluation, and based on Mathews graphic method, the stability of stope, stope roof and hanging wall rock mass is analyzed and demonstrated. It is concluded that quartzite and silty slate in Dadong gold mine belong to poor rock mass, and shallow hole retaining is adopted In order to ensure the stability of the hanging wall rock, the safety is poor and the loss and dilution rate is high. In order to ensure the stability and reliability of the whole stope, the wall cutting and filling mining method is proposed for mining, and the stope structure and mining technology are determined. The mining results show that it is reasonable to select the wall cutting and filling mining method as the mining scheme, and the ore dilution rate is reduced by 35%, The ore loss rate is reduced by 16%, and the expected technical and economic effect is good.
- 1
Study on intelligent evacuation simulation of mine fire - Taking a copper mine in Xinjiang as an exampleAbstract:
In order to investigate the safety evacuation of fire in metal mines, this study used a Copper Mine as the engineering background, simulated the dynamic changes of smoke, CO concentration, visibility, wind speed and wind pressure under three fire scenarios during shaft ventilation by FDS. Based on the evacuation tools, roadway evacuation speed and personnel capacity, the Pathfinder simulation was used to obtain the evacuation action time and personnel flow variation rules of 27 mine evacuation scenarios. Finally, based on fire evacuation simulation results and relevant empirical formulas, the safety of mine fire evacuation was quantitatively determined. The results show that the anti-wind effect of this copper mine under fire meets the requirements of safety regulations. Measures such as adding refuge chambers at the interface between the cage shaft and the inclined roads in the middle section are more conducive to safe evacuation The combination of FDS and Pathfinder not only optimizes the metal mine fire evacuation model, but also provides a case model basis for mine fire evacuation simulation teaching.
- 1
Experimental study on the influence of deep frozen clay structure on deformation characteristicsAbstract:
In order to study the influence of deep frozen clay structure on deformation characteristics, unconfined uniaxial compression tests were carried out on undisturbed soil and remolded soil at different temperatures in Huaibei coal mine. The results show that: undisturbed soil is softened at three temperatures, remolded soil is hardened at - 5 ℃, and softened at - 10 and - 15 ℃; with the decrease of temperature, the peak strength of undisturbed soil and remolded soil increases, and the peak strength of undisturbed soil is greater than that of remolded soil, and the peak strength is close to that of remolded soil at - 15 ℃; the difference of peak strain is obvious, and the peak strain of remolded soil is greater than that of original soil The elastic modulus of undisturbed soil is 1.5 times of that of remolded soil at - 5, - 15 ℃ and almost close to that at - 10 ℃. The deformation characteristics of undisturbed soil and remolded soil are obviously different, which mainly depends on the content of unfrozen water, open and closed pores and temperature in the soil, and the analysis of them has certain engineering reference value.
- 1
Numerical Simulation Study of the Influence of Coal Particle Size on Gas Diffusion ProcessAbstract:
In order to study the influence of coal particle size on gas desorption and diffusion process, the single hole model and diffusion factor model were used to simulate the desorption process of Liuta coal with different adsorption equilibrium pressures, ranging from 0.074 mm to 3 mm. By comparing the fitting degree between simulated data and experimental results under different diffusion factors, the law of diffusion factors changing with particle size was analyzed. The results show that the diffusion coefficient is not constant, which is related to the change of temperature and pressure during desorption and diffusion. With the increase of coal particle size, the gas desorption rate decreases, the diffusion coefficient D of single hole model increases, and the diffusion factor value increases monotonously. The fitting effect of diffusion factor model is better than that of single hole model in the middle stage of desorption process, and because the pressure at the center of coal particle decreases continuously, the diffusion coefficient value increases continuously. According to the law of diffusion factor changing with particle size, the diffusion factor of the same coal at any particle size can be obtained, and then the complete desorption curve can be obtained, which has a certain guiding role for practical engineering.
- 1
Odor source identification method based on the cuckoo algorithm researchAbstract:
Reasonable use of odor source detection technology can effectively help companies and even the country eliminate many hidden safety hazards. In recent years, the method of using intelligent robots combined with odor sensors has been widely used to deal with the problem of odor source location. Aiming at the problem of low efficiency of single gas source history detection in complex airflow environment. The paper proposes a smoke plume detection strategy based on a fixed step length of Levi's flying random walk and a smoke plume tracking strategy based on a cuckoo search algorithm. First, the use of a fixed-step Levi flight random walk plume discovery strategy can more effectively locate the space area, and then, the use of the cuckoo search algorithm based plume tracking strategy can effectively jump out of the local concentration extremes, making the olfactory robot Quickly converge towards the source of the smell. In the experimental part, we simulated the real environment for simulation experiments. The results show that compared with standard strategies such as Z-line plume discovery, related random walk motion, Brown random walk motion, etc., this strategy has smaller errors in a complex airflow environment. The advantage of faster convergence can better help the robot to jump out of local concentration extremes and quickly converge to locate the source of odor.
- 1
Research on the Influence of Seepage Pressure and Porosity on Tunnel Surrounding Rock DeformationAbstract:
Aiming at the seepage phenomenon that occurs in the main aquifers of crushed silty clay and massive rocks, numerical analysis methods are used to apply different seepage pressures under the premise of limiting the porosity of the rock mass to analyze the forces and deformations of surrounding rocks. Change the initial value of porosity under the condition of limiting the seepage pressure of the rock mass, and explore the influence of porosity on the deformation of tunnel surrounding rock. Subsequently, a tunnel surrounding rock model under the combined action of two-factor variables is established. The porosity takes ten sets of data in the interval of 0.05-0.5, and the maximum value of the seepage pressure is three sets of data in the interval of 2.0-2.2Mpa, and the bivariate assignment is cross-combined After analyzing the effect of its interaction on the surrounding rock deformation, and comparing the two main influencing factors. The results show that with the increase of seepage pressure, it is mainly manifested by the increase of pore water pressure and the sharp increase of surrounding rock displacement. Among them, the rock mass deformation is the most significant in the area of ??broken surrounding rock. When analyzing the vertical displacement of the surrounding rock, the porosity of the above two variables is the main influencing factor, while when analyzing the displacement of the surrounding rock in other directions, the main factor should be determined according to the specific situation.
- 1
Research on ore identification and separation based on improved Algorithm of PSO-faster R-CNNAbstract:
Against one of the important steps of ore sorting ore production process, the traditional manual to identify mineral categories inefficient, complex and use of mineral processing equipment energy consumption, and to improve efficiency of mineral separation, separation of the ore recognition algorithm based on machine vision is studied. Improved algorithm using the PSO - Faster - R - CNN to ore 2 d image identification classification, PSO algorithm is improved Faster - R - CNN algorithm convergence speed, using the multi-scale feature fusion method, realized the recognition of certain minerals, end of ore sample image recognition test. , also chose the HOG + contrast experiment and KNN algorithm, the SVM algorithm results show that the improved algorithm PSO - Faster - R - CNN recognition accuracy is as high as 98%, the precision and stability is better than the other two algorithms, the actual project identification speed, can meet the needs of the ore sorting recognition application in the future.
- 1
Research on compressive deformation characteristics of broken rock under different loading ratesAbstract:
In order to study the compressive deformation of broken rock under different loading rates, the crushed rock with a specific particle size was used as the test object, considering the underground stress and particle size distribution characteristics of the broken rock, conducted constrained compression tests under different loading rates. The results showed that: the time for fractured rock samples to reach peak pressure at different loading rates shows a negative correlation with the loading rate, when the loading rate is 5mm/min, the time required to reach the peak pressure is the shortest, only 300s, and the load-time curve approximately shows elastic deformation. Similar stress-strain curves show a "concave upward" form under different loading rate conditions, and the curve gradually becomes flat with the increase of loading rate. Similarly, the deformation modulus-stress curve shows approximately linear changes under different loading rates, and the peak value of the deformation modulus decreases with the increase of the loading rate, among them, the deformation modulus is the largest when the peak pressure is reached at a loading rate of 1mm/min, which is 360MPa. The broken rock sample after the screening test shows that the proportion of the rock sample with a particle size of 0-2mm when the loading rate is 5mm/min is 1.17 times that when the loading rate is 1mm/min.. The above research results have certain guiding significance for the safe mining of mines.
- 1
Laohutai Mine -280 Level And the Effect of Continuous Mining in Chronological Order on the Movement and Deformation of Overlying StrataAbstract:
In order to study the influence of the Laohutai Mine -280 level and the chronological continuous mining in the earlier multiple mining areas on the movement and deformation of the overlying strata, Midas and Flac3d are usedNumerical simulation methods like -280 level and early multiple mining areas are continuously mined in chronological order, and surface subsidence and displacement are obtained respectively, and dangerous boundaries, moving boundaries, boundary angles and movement are obtained through indicators such as tilt deformation, horizontal deformation, and curvature. angle. Studies have shown that with the increase in the number of mining areas, the overlying rock mass has been damaged and disturbed more frequently, resulting in an increase in the scope of movement and damage. The surface reservoir has a great safety hazard, but it does not affect the Meidu Road. Safety.
- 1
RISK ASSESSMENT OF COAL MINE ROCK BURST BASED ON ANALYTIC HIERARCHY PROCESS AND UNCERTAINTY MEASUREMENT THEORYAbstract:
At present, the influencing factors of rock burst in coal mine are mostly complex, most of which are fuzzy and uncertain. Therefore, the traditional evaluation model is difficult to reasonably evaluate the coal mine rock burst. Aiming at the problem that it is difficult to determine the coal mine rock burst, a risk assessment model of rock burst based on analytic hierarchy process (AHP) and unascertained measurement theory is proposed. The model allocates reasonable weight of the influencing factors of rock burst with the help of analytic hierarchy process (AHP), and the uncertainty is evaluated by unascertained measurement theory The evaluation model uses the minimum unascertained measure distance discrimination method to determine the level of the object to be measured. According to the actual mining situation of Xiagou coal mine, the rock burst risk of zf303 working face is evaluated. Based on the risk evaluation model, the evaluation set of four grades of rock burst risk, namely weak, medium, strong and extremely strong, is set up. Through the final calculation, the rock burst risk of zf303 working face in Xiagou coal mine is evaluated as "medium". The evaluation results of the evaluation model are in accordance with the actual situation of Xiagou coal mine The actual engineering of zf303 working face in Xiagou coal mine is consistent. The results show that, based on the evaluation model, the impact ground can be predicted, and the evaluation results are more accurate, which can provide some guidance and suggestions for the anti scour work.
- 1
Comparative analysis of Tailings Re-concentration Process of a Gold Mine in Henan ProvinceAbstract:
A gold mine tailing pond in Henan Province has a total of 800000 tons with a grade of 0.74 g/t, which has a high recovery value. In order to develop secondary resources and improve the utilization rate of resources, the properties of the tailings were analyzed, and ultrasonic dispersion flotation test, high gradient magnetic separation test, gravity separation test by Knelson concentrator and leaching test were carried out. The results indicated that the main forms of gold in tailings are exposed semi naked gold, carbonate wrapped gold and sulfide ore wrapped gold, and there are a certain amount of long horned grain and wheat grain grain gold. Besides, the gravity separation by Knelson concentrator and leaching process has certain adaptability to the gold tailings, which can obtain a good beneficiation indexes. This study provides a reference for the production practice of mining enterprises
- 1
Model Test of Tailings Pond Dam Break Under Different Failure ModesAbstract:
Taking a tailings pond in Liaoning province as the prototype, the model test platform was built independently and the model test of tailings pond dam break under two different failure modes, namely overtopping of rainstorm flood and dam slope pipe gushing, was carried out respectively.The failure mechanism and failure process under various working conditions are compared and analyzed from the aspects of dam break development process, influence range and damage degree, etc., and the adverse working conditions are obtained, so as to provide basis for the safe evacuation of downstream residents and the formulation of reasonable disaster relief measures.The results show that the lack of flood control capacity and discharge capacity of tailings ponds is the key to the formation of dam break model.The failure process and mechanism of the two failure modes are quite different.Compared with flood overtopping damage, dam break caused by piping failure is more serious and affects a wider range, so the downstream relocation range can be determined accordingly.
- 1
Technology Study on a Zinc Concentrate to Reduce AsAbstract:
A lead-zinc sulfide ore adopted a priority flotation. Its lead tailing use lime as the depressor, copper sulfate as the activator, butyl xanthate as the collector, and the zinc middlings returns sequentially. The As content of produced zinc concentrate was over 0.7%. In this study, Zn-S iso-flotation is selected as the flotation flow-sheet, the amount of lime is reduced, the recycling load of middling is relived, and good flotation index is achieved. Zinc concentrate contains 49.58% zinc and zinc recovery The rate is 90.58%, and the arsenic content of zinc concentrate is reduced to 0.27%. The goal of reducing As content in zinc concentrate is achieved by the optimization of the flotation process structure.
- 1
Research on the integration of business and finance in the construction of coal mine enterprise HallAbstract:
Drawing on the practice of government administration hall, an enterprise hall was established in coal mine, with one person from each department to work collectively in the enterprise hall to provide one-stop service for grass-roots employees. Without changing the pagoda like layered structure, the management mode was changed into the service mode, and the flexible flat organizational structure was constructed, which opened a new way for the reform of coal mine grass-roots governance structure. On the basis of the establishment of enterprise hall, the information service system of coal mine enterprise hall is constructed to realize network office and mobile app office. By establishing basic data unit, dividing operations, implementing zero base budget, flexible budget and rolling budget, and promoting the integration of industry and finance, an intelligent enterprise hall is established. In coal mines, the integration of industry and finance can extend the management of coal mines in two directions: one is for the grass-roots level to improve the management level at the grass-roots level, and the other is for the decision-making level to enhance the scientific decision-making level of the decision-making level. In coal mines, the integration of industry and finance is the basic work of building smart mines, which can raise the construction of smart mines to a new height.
- 1
Fuzzy Evaluation on the Influencing Factors of Unsafe Behaviors of intelligent Mine WorkersAbstract:
In order to effectively control the unsafe behavior of intelligent mine workers, scientific quantification and evaluation of its influencing factors are carried out. By constructing an evaluation system including 3 first-level indicators and 10 second-level indicators, the AHP-entropy weight method is used to determine the subjective and objective weights of each indicator, and the fuzzy comprehensive evaluation method is used to construct an evaluation model for the factors affecting unsafe behaviors of intelligent mine workers . Take a intelligent mine in Yulin as an example, and conduct a comprehensive evaluation and analysis. The results show that the occurrence of unsafe behaviors of intelligent mine workers is mostly affected by management factors, followed by operational factors and individual factors. Based on this, targeted control and improvement measures have been proposed. The evaluation result is basically consistent with the actual safety production situation, indicating that the model has a certain degree of scientificity and practicability, and can provide a reference for the prevention and control of unsafe behaviors of intelligent mine workers.
- 1
Experimental study on factors affecting flocculation sedimentation and thickening of unclassified tailingsAbstract:
In order to explore the influencing factors of flocculation sedimentation and thickening of unclassified tailings (UTs) in a gold mine, the feeding concentration, flocculant molecular weight, flocculant unit consumption and flocculant solution concentration were taken as the influencing factors, and the maximum average sedimentation velocity , final sedimentation thickening time and ultimate underflow concentration were taken as the indexes to carry out the orthogonal test of flocculation sedimentation and thickening of UTs. The results were analyzed by SPSS 23 software. The results show that the order of significance of the influence on the three indexes of the maximum average sedimentation velocity, final sedimentation thickening time and ultimate underflow concentration is feeding concentration, flocculant molecular weight, the unit consumption of flocculant and flocculant solution concentration. It is recommended that the parameters of flocculating sedimentation and thickening of UTs in the gold mine are as follows: the feeding concentration of UTs slurry is 20%, the molecular weight of flocculant is 15 million, the unit consumption of flocculant is 40 g/t, and the concentration of flocculant solution is 0.3%.
- 1
Analysis of stress State of Shaft during Operation period considering the influence of temperatureAbstract:
In order to study the stress on the shaft lining and surrounding rock caused by the temperature and the material property of the shaft lining with the change of time, the elastic mechanics prin-ciple and heat conduction principle of the shaft lining and surrounding rock are derived.The ex-pressions of temperature stress of shaft and surrounding rock are deduced.The creep property of surrounding rock and surrounding rock is considered in the derivation process, and the analysis shows that the temperature variation field of surrounding rock and surrounding rock during the operation period is a seasonal periodic change, and the temperature variation of surrounding rock eventually tends to zero with the increase of distance from the shaft center. Considering the time factor, the stress field of shaft is related to the creep degree parameter of surrounding rock mechanics, and the creep parameter of surrounding rock should be considered when designing shaft.
- 1
Study on high and low grade layered mining method of underground bauxiteAbstract:
In view of the mining problem of high-grade ore with thin lower limit and large variation, combined with the physical characteristics and mining requirements of bauxite, the paper analyzes the characteristics of nearly stratified distribution of high-grade and low-grade ores in underground bauxite. Based on the existing comprehensive mechanized mining technology of coal mine, this paper puts forward the problem solution of new bauxite mining machine suitable for bauxite mining conditions, puts forward the bauxite slicing mining technology, and lists the detailed process steps. This paper puts forward two key cores, i.e., "the method of oblique cutting and feeding with distance lifting rocker arm" and "the mining method of retaining floating material with bottom knife", and expounds in detail the difference between the two key cores and the characteristics of "mining method of high and low grade double-layer ore" and "mining method of three-layer high-grade ore". In order to ensure the smooth implementation of layered mining, several key points are put forward, such as separate mining, separate transportation and storage system, matching between two roadways and mining face, rapid determination method of high-grade ore material stratification, loading mode of high-grade ore material, loading mode of medium and low-grade mineral material, etc. The progress and status of underground bauxite comprehensive mining project and the stage achievements of layered mining technology are summarized. Finally, the characteristics and applicable areas of the high and low grade slicing mining method of underground bauxite are summarized.
- 1
Study on division and ecological restoration suitability of rock slope in Tongshankou Copper MineAbstract:
Ecological restoration of mine slope is of great significance to promote the construction of ecological civilization in China. In order to objectively and accurately evaluate the suitability of ecological restoration of rock slope, an evaluation system covering 9 influencing indexes including slope geometric characteristics, rock mass structure and mechanical characteristics, and soil meteorological conditions in mining area was established on the basis of the division of rock slope. The suitability classification standard for ecological restoration of open-pit rock slope was established, and the suitability evaluation of 7 typical zoning slopes in Tongshankou Copper Mine was carried out. The results show that: (1) Slope angle, rock mass integrity coefficient, slope orientation and structural surface density dominate the ecological restoration suitability rating, with a weight of 77.2%. (2)Among the seven typical slopes, area 6 slope is particular suitable for ecological restoration, and zone 1 slope, zone 2 slope, zone 3 slope, zone 4 slope, zone 5 slope and zone 7 slope are basically suitable for ecological restoration. The study on the suitability of ecological restoration of rock slopes based on fuzzy comprehensive evaluation has an important reference basis for the reasonable selection of ecological restoration schemes of mine slopes.
- 1
FIRST EXPLORATION OF THE SETTING PERFORMANCE CLASSIFICATION OF PASTE BACKFILL MATERIALS BASEDON THE SUCTION EVOLUTIONAbstract:
The setting performance of paste backfill materials can significantly affect the safety and efficiency of mining production. However, the standard of setting performance of paste was developed with respect to the masonry mortar. This standard has poor adaptability for the backfill mining, since the strength of masonry mortar is usually in the range of 5 to 30 MPa, and the strength of backfilled paste material has a range of 0.2 to 5 MPa. Therefore, a series of strength and suction experiment were conducted for the paste at various curing ages and initial temperatures. On the basis of these experimental results, the suction and strength at various initial temperatures were correlated. Furthermore, a method of setting performance division was proposed, which unified the suction and strength. It is named as incubation period when the uniaxial compressive strength (UCS) is 0~0.075 MPa, and setting period as the UCS is 0.075~0.153 MPa. When the UCS is 0.075 MPa, the paste reached initial setting state. As the UCS is bigger than 0.153 MPa,it is termed as final setting. The new setting performance classification method is better consistent with the practical application strength of paste filling.
- 1
Optimization of mine ventilation network monitoring layout based on the principle of minimum spanning treeAbstract:
In order to solve the problems that the existing mine ventilation system does not have a reasonable planning and layout at the monitoring nodes, and the monitoring points fail to reflect the changes of the mine ventilation system in time.This paper puts forward the optimization technology of the monitoring layout of the mine ventilation network by using the minimum spanning tree principle. This technology is based on graph theory and establishes the corresponding mathematical network model according to the actual mine ventilation system, and uses the minimum spanning tree algorithm to assign weighted ventilation network diagrams to the ventilation branches to solve the smallest spanning tree, and obtain the network remaining branch combination with the largest weight. Determine the monitoring point as the largest remaining branch combination, and calculate the air volume of each branch of the system by calculating the remaining branch air volume obtained from the monitoring.This technical method can effectively reduce the number of monitoring points of the ventilation system, reflect the changes in the air volume of each branch of the ventilation network in real time, improve the accuracy and economy of the monitoring system, and solve the problem that the ventilation network monitoring cannot reflect the actual air volume of the mine. The layout of the ventilation monitoring system has important guiding significance.
- 1
3D Pore Structure and Seepage Simulation of Calcium Glauberite under Multi-field CouplingAbstract:
The leaching mining of glauberite is a multi-field coupling process, and each factor will change its connectivity, thereby affecting its permeability characteristics. In this paper, the glauberite was taken as the research object. On this basis, Micro-CT technology and AVIZO three-dimensional reconstruction software were used to establish a model of the microscopic pore structure of glauberite. Then, their changes in internal connectivity were quantitatively characterized after the action of fresh water solutions at different temperatures. On this basis, the mesoscale seepage simulation was carried out, and the permeability characteristics of glauberite after different temperature of fresh water solution were studied. The results show that the connectivity and permeability of glauberite are positively correlated with temperature. At 35℃and 65℃, the pore spaces inside glauberite are mostly small holes and short channels, with poor connectivity and narrow seepage channels; at 95℃, the pore spaces are mostly large holes and long channels, with good connectivity and relatively broad seepage channels. The permeability from 35℃ to 65℃ increases slightly, only with an increase of 0.23μm2.The permeability of glauberite at 65℃ to 95℃ increases sharply, with an increase of 2.75μm2.The results of this study have important significance for improving the mining efficiency of glauberite deposits and the stability of layered salt karst reservoir.
- 1
Research of Quantitative Grouting Reinforcement Technology for Surrounding Rock Roadway with Complex StructureAbstract:
In order to solve the problems of difficult support of surrounding rock masses and large deformation of surrounding rocks in complex structures, quantitative split grouting reinforcement technology was used to grouting and reinforce the faults and subsidence column sections of auxiliary transportation lanes in the second mining area of Licun Coal Mine to improve complex structures The overall bearing capacity of the surrounding rock mass. According to the split grouting shape of the surrounding rock mass of the structure and the supporting technology of the broken surrounding rock shell, the bearing mechanical model of the shell after grouting reinforcement is established, the critical bearing shell thickness to ensure the stability of the surrounding rock is derived, and the surrounding rock mass Quantitative grouting reinforcement expression; Using 3DEC numerical simulation software to analyze the slurry diffusion law, the relationship between grouting pressure 、Crack opening and slurry diffusion radius and diffusion shape was obtained. Based on the above research conclusions, the design and implementation of quantitative split grouting reinforcement scheme were carried out. The results show that after the grouting reinforcement is implemented, the broken surrounding rocks in the range of 0 ~ 3m are effectively cemented together to form a bearing shell, which solves the problem of large deformation of surrounding rocks and has a significant grouting effect.
- 1
Experimental research on upper limit of mining under thick loose aquiferAbstract:
Reasonable leaving coal and rock pillar for safety has great significance for safe mining under thick loose aquifer and liberation of shallow coal resource . Based on the Geological mining conditions of Yuandian No. 2 Mine, this paper uses mathematical analysis, laboratory tests, similar simulation and numerical simulation to analyze the sensitivity of major factors affecting the height of the caving zone, establishes a theoretical formula for the height of the caving zone, and verifies the accuracy of the new theoretical formula. The results of the study show that the high content of clay minerals in the bedrock weathering zone, poor permeability, and strong regeneration capacity and separating ability, which has the dual role of preventing and inhibiting the development of the height of the water conduction fissure zone. The Mining height is the main factor affecting the height of the caving zone, the sensitivity reaches 0.74; there is advanced supporting pressure in front of the working face, the rock layer is compressed to cause the temperature to rise, and the cover rock is first pulled to produce cracks, which reduces the temperature; the maximum height of the caving zone formed is 10.3m, and the maximum height of the water conduction fissure zone is 57.5m. According to the above research results, the mining upper limit of the working face can be increased by 30m.
- 1
MAIN FREQUENCY CHARACTERISTICS OF ACOUSTIC EMISSION DURING ACCELERATED CREEP STAGE OF RED SANDSTONEAbstract:
Rock creep is the main factor inducing pillar failure. The creep acoustic emission(AE) tests of red sandstone were carried out,and the main frequency characteristics of AE corresponding to the starting point and the ending point of accelerated creep were analyzed. The results show that: there is a sudden increase of AE amplitude at the beginning and at the end of accelerated creep, and the corresponding AE dominant frequencies are 125kHz ~ 156.25khz and 218.75khz ~ 250kHz, respectively. This feature can be used as a qualitative and quantitative precursory feature of red sandstone stepping into accelerated creep stage and creep failure. The research results can provide the basis for the determination of pillar stability in metal mines.
- 1
Study on the Influence of Surrounding Rock Swelling Force on Inclined Well Support under Freezing-thawing ConditionAbstract:
In view of the special engineering properties of expansive mudstone during freeze-thawing process, combined with the large deformation phenomenon of the main inclined well of Chagan Zhuar No. 1 well during the construction of artificial freezing method, the influence of different expansive forces on the inclined well support structure was studied by numerical simulation method. Based on the thermal coupling module in FLAC3D, the process of frost heaving and thawing swelling of the expansive rock in the construction of the main inclined well freezing method was simulated. By comparing the deformation law and stress situation of the two supporting structures under different conditions of expansive force, it was concluded that the horseshoe-like supporting structure could effectively resist the deformation of borehole wall and enhance the stability of wellbore. The research results can provide reference for support optimization and construction of similar projects.
- 1
Study on the Fractures Development Law of Collapsible Loess Surface in MiningAbstract:
The development of surface fractures in collapsible loess area is particularly severe affected by the collapsibility in coal mining. Taking a mine in Shenmu as the background, Using theoretical analysis, theoretical calculations and laboratory tests as research methods, combined with FLAC3D numerical simulation technology, relevant research is carried out on the generation mechanism and development laws of collapsible loess fractures in coal mining surface. The results show that: 1) The fractures are caused by the horizontal deformation of ground surface exceeding the limit tensile deformation value of soil. Based on Mohr-Coulomb strength theory and mining subsidence prediction theory, the prediction formula for the development depth of surface fractures in mining is derived. 2) The laboratory test results show that the cohesion of saturated collapsible loess decrease by 71% compared with the natural state, the internal friction angle decrease by 59%, the deformation modulus decrease by 39%, and the Poisson’s ratio increase by 28%. Loess collapsible deformation and strength attenuation caused by rainfall infiltration in the rainy season directly lead to intensified surface fractures. 3) According to the formula for predicting the development depth of surface fractures, it is concluded that the fractures development depth on loess surface is increased by 77% under the influence of collapsibility, which is consistent with the results of numerical simulation and field measurement. The research can provide a useful reference for study of the law of mining surface damage under similar geological conditions.
- 1
Experimental Study on the Coagulation and Flow Characteristics of Nano-material Modified Cement SlurryAbstract:
In order to solve the difficult problem of grouting for micro-cracks in deep underground rock masses,it is necessary to develop a low-viscosity cement slurry.Through the method of combining physical experiment and orthogonal experiment analysis, four factors including the content of ultra-fine fly ash, the content of nano silica sol, the content of water reducing agent and the water-cement ratio are comprehensively studied, and the coagulation characteristics and flow characteristics of the slurry are explored. And the changing law of flow characteristics.The test results show that the water-cement ratio has a greater impact on the performance of the modified cement slurry.The increase of the water-cement ratio will increase the setting time of the slurry,and the viscosity and stone rate will decrease significantly.Water reducer and ultra-fine fly ash can effectively improve the flow characteristics of the slurry.Nano-silicate sol has a significant effect on the coagulation characteristics of the slurry.When the amount of nano-silicate sol increases,the coagulation time of the slurry decreases,the stone rate increases,and the viscosity increases slightly.
- 1
RESEARCH ON DEVELOPMENT AND APPLICATION OF PHYSICAL PLANE SIMULATION EQUIPMENT IN MINEAbstract:
Aiming at the problems of unbalanced loading of the current similar simulation experiment device, low accuracy of simulated internal load, uneven distribution, water bag pressure loading, which is prone to leakage, water bag rupture, and inconvenient maintenance, a similar simulation of air pump loading has been developed. experimental device. In order to verify the reliability of the device, taking the fully mechanized caving face of Zhongmei Tashan Mine as an example, the law of overlying rock movement during the mining process of the fully mechanized caving face under the old goaf was studied, and UDEC numerical simulation was used to compare similar simulation results. It is concluded that as the mining distance increases, the coal seam directly collapses and connects to the overlying old goaf. After further mining, the upper basic roof breaks, and the collapse zone rapidly develops to a position 60 m above the coal seam. After that, the overlying rock The development height of the three belts gradually increased and remained stable, while the collapsed belts were compacted. The numerical simulation results are consistent with similar simulation results. It shows that the experimental device is stable and reliable, and can be widely used in the teaching and scientific research of mining engineering.
- 1
The Stability Analysis of the Large Hexagonal Approach in the Layered ConstructionAbstract:
In order to increase stope production capacity and reduce mining costs, the access section was enlarged on the basis of the existing downward hexagonal access cemented backfilling mining method. The force analysis and theoretical calculation as well as field industrial tests were carried out to analyze the stability of the large hexagonal approach. The results show that the large hexagonal approach can withstand the upper load without shear collapse of the backfilling. And the safety factor of the side slope of the backfilling is 2.83, indicating that the side slope of the backfilling will not be damaged; the safety factor of the side slope of the orebody is 4.26, which indicates that the orebody can be kept stable under the recommended structure parameters. Field industrial tests show that the inverted trapezoid at the lower part of the large-section hexagonal approach was relatively flat and did not show large collapse during the mining process, and the overall stability was well.
- 1
Improved A* algorithm global path planning based on dynamic analysis of the mining vehicleAbstract:
In order to generate an optimal path for mining vehicles to avoid obstacles, An enhanced A* algorithm was proposed. Based on the dynamic analysis of climbing, and the time cost of climbing different slopes was calculated. A simulation grip map of polymetallic nodule mining area, with the unique topographic elements of polymetallic nozzles, is proposed. To take time cost and distance cost into comprehensive consideration, cost function g(n) of the traditional A* algorithm was changed into the weighted sum of distance cost function and time cost function. Curve fitting and redundant node deletion method were then adopted to smooth the path by avoiding sharp 45 degree turns around corners. The simulation results show that the improved A* algorithm can generate a optimal obstacle avoidance path by choosing appropriate parameter a. Using the number of crossings and path consumption as evaluation indicators, the value of the parameter a in the cost function of the improved A* algorithm is obtained.
- 1
A Coupled Gas-Solid-Thermal Model for Coal-bed Methane Desorption-Diffusion-FlowAbstract:
Considering the temperature change caused by coalbed methane desorption and its influence on subsequent desorption and free gas state of adsorbed gas, considering the dynamic change of gas diffusion coefficient and its influence on the cross flow term, the gas- solid- thermal coupling model of gas desorption- diffusion -seepage process in coal seam is established based on the pore and fracture dual medium model, and the numerical simulation and mechanism of coalbed methane extraction process are carried out. The results show that: (1) The influence of temperature change on gas pressure is opposite to the influence on gas content; (2) the unmodified Langmuir model takes into account the temperature reduction and its influence on the gas diffusion and seepage process, but does not consider the influence of the temperature reduction on the gas desorption, which will lead to the larger estimated value of the CBM extraction amount; (3) the isotropic model is available The results show that the gas content curve consistent with the anisotropic model can be obtained, but the gas content distribution is significantly different. The seepage advantage of coal seam caused by permeability anisotropy is greater than that caused by the layout of drainage holes; (4) when the diffusion coefficient is high, the seepage process is the restricting link affecting the extraction efficiency of coalbed methane, and the anisotropy of permeability must be considered The influence of property on the whole process of gas migration.
- 1
Stability analysis of large slag dump under rainfall-Earthquake coupling actionAbstract:
Abandon slag field for research of unsaturated soils under the action of rainfall infiltration and vibration coupling abandon slag field stability problem, a abandon slag field in yunnan as an example, on geological exploration data, abandon slag field lab experiment and field experiment data as the basis, using GeoStudio software two steady state and transient state are on the same model comparing the two kinds of different situation, steady abandon slag field model applying conditions of groundwater, transient abandon slag field model basis on worksite conditions of groundwater and research the most heavy rain last 24 hour rainfall conditions and earthquake dynamic field;The results show that heavy rainfall will lead to a rapid increase in the permeability coefficient of the shallow soil in the slag dump site, and the moisture content of the shallow soil is close to saturation, which greatly reduces the matric suction between soil particles, affects the effective stress of the soil layer, and reduces the shear strength of the slag dump site.After applying the seismic dynamic field on this basis, instantaneous tensile stress and tensile cracks are generated, resulting in the decrease of tensile strength of the slope top. The generation of cracks promotes the infiltration of rainwater after the earthquake and slows down the dissipation of excess pore water pressure.Area proportion is not big, but after the earthquake liquefaction soil platform focused on the first level, abandon slag field lateral displacement peak, peak shear strain is lesser, shear strain concentration area in the third grade and diluvial soil slope under given soil junction, did not cause obvious shear deformation to abandon slag field, no slip trends, determine the rainfall seepage coupling - earthquake under the action of the abandon slag field is stable.
- 1
Analyze the influence of superheated steam on Coal gas desorption with pore structureAbstract:
In order to explore the influence of hot steam on the gas desorption capacity of coal mass; taking the lean coal of Yangquan Xinyuan Coal Mine as the research object, the mercury intrusion method was used to analyze the pore structure evolution of coal before and after the hot steam treatment, combined with the adsorption-desorption experiment, and the desorption rate The critical value of sum desorption time characterizes the effect of hot steam on coal gas desorption. The results show that: 1) After thermal steam treatment, the total pore volume, hysteresis ring area, porosity, permeability and average pore diameter of the coal body are increased. The connectivity of the structure is significantly improved; 2) The coal gas desorption rate increases with the increase of equilibrium pressure; the use of hot steam effectively promotes the desorption of residual adsorbed gas in the coal, and eliminates the influence of moisture in the coal to inhibit gas desorption. The gas desorption rate is significantly increased; 3) The critical value of the time effect of coal gas desorption under the action of hot steam is significantly reduced, the time required for desorption to reach equilibrium is shortened, and the desorption efficiency is significantly improved. The research provides a certain theoretical basis for coal seam heat injection to strengthen coalbed methane mining.
- 1
RESEARCH ON PARAMETER MATCHING OF FULL ANCHOR CABLE SUPPORT IN TOP-COAL ROADWAYAbstract:
Aiming at the engineering problems of roof subsidence and support failure of 80807 working face return air channel, this paper firstly analyzes the deformation characteristics and main control factors of the roadway supporting top coal. Secondly, the paper studies the supporting effect of roadway under different supporting body lengths and pretension, and puts forward the advantages and disadvantages of anchor cable support and the necessity of long and short anchor cable combined support. Through numerical simulation, the roadway deformation and roof compressive stress distribution under different pretension matching are compared, and the priority of short anchor cable pretension promotion is higher. According to the research conclusion, the industrial test scheme is determined and applied to the site. The control effect of surrounding rock is obviously optimized.
- 1
Causes and Solutions of Surface Boulders in Open Pit Blasting in Yulong Copper Mine of TibetAbstract:
High big boulder rate is a common phenomenon in high bench blasting of open pit mines. In Yulong copper mine, which is located in the frigid and high-altitude area of Tibet, the high surface big boulder rate is especially obvious on account of the freeze-thaw cycle and other influences. In combination with the geological conditions, environmental factors and the effect of blasting operation in Yulong copper mine, the blasting parameters are optimized by analyzing and adjusting the hole spacing, row spacing and charge structure. After a number of adjustments and experiments, the high surface boulder rate is distinctly improved, the surface boulder rate is stably controlled within 3% and good results has been obtained.
- 1
Discrete Element Simulation of Ground Collapse Characteristics in Goaf of Gypsum MineAbstract:
As the Pibei gypsum mining area an important gypsum producing area in Jiangsu Province and it’s goaf collapse disaster caused by the massive mining of gypsum having become more and more serious, understanding the process of goaf collapse and the controlling factors is important for protecting the lives and property safety of people. Based on the typical engineering geological conditions of the Xizhou gypsum mine, this paper studied the influence of the number and size of the stope room, the width of the pillars, the thickness of the protective?top-layer?in the goaf collapse characteristics and influencing factors of collapsed arch stability and revealed the characteristics and mechanism of goaf collapse by using MatDEM to establish a discrete element model. As the depth and influence range of the collapsed pit in the simulation results being similar to the actual survey results, the feasibility of using discrete elements in the research of ground collapse in the goaf of gypsum mine was verified, and it provided a theory for monitoring design, prediction, and disaster prevention and control of the goaf of Pibei gypsum mine.
- 1
Prediction and analysis Of Shaft Damage Caused by Coal Pillar In Industrial Square MiningAbstract:
In order to ensure the safe operation of the mine shaft during the mining of the pillars of the Niuerzhuang Mine Industrial Square in the Fengfeng mining area, the damage of the main shaft shaft was studied through FLAC3D. Different sizes of subsidence and horizontal movement were applied to the model to simulate the mining production. The impact of the sinking and inclination of the main shaft on the shaft, the critical deformation value of the main shaft failure is predicted, and the measured deformation data of the main shaft of Niuerzhuang Mine is applied to the model as the displacement boundary conditions to determine the current mining impact on the main shaft. influences. The research results show that the critical compression deformation of the main wellbore is 1.7mm/m and the tilt deformation is 4mm/m. At present, the deformation value of the main wellbore is still less than the critical deformation value of the wellbore, and the wellbore is still in a safe state; in addition, analyze the potential range of shaft damage during subsequent mining,it provides support for the safe operation of the main shaft during the mining of coal pillars in the Niuerzhuang Mine Industrial Plaza. At the same time it will have reference significance for other industrial square coal pillar mining under similar geological conditions.
- 1
Application of Air spacers When Encountering Karst caves In LimestoneAbstract:
Karst caves are common in limestone mines. The parameters of borehole net and single-hole blasting should be adjusted according to the burial condition and volume of Karst cave. Using Air Spacer equipment should be processed from the following three aspects: 1.accurate placement of the appropriate equivalent explosive in the corresponding ore body (reasonable minimum resistance line); 2.accurately controlling the plug length of the hole; 3.ensuring the quality of borehole plugging. It will implement the designed parameters of borehole net and single-hole blasting to ensure the blasting quality and blasting damage controlled.
- 1
Experimental and numerical simulation of semi industrial loop pipe transportation of tailingsAbstract:
In order to explore the internal flow characteristics of the pipeline during the whole tailings paste filling process, through the semi industrial loop pipe test, combined with the Bingham rheological equation applicable to the paste flow characteristics, the pipeline pressure loss and slurry flow characteristics during the pumping process with different slurry ratio and cement sand ratio were tested, and the flow pressure attenuation of paste pipeline under different slurry concentration and cement sand ratio was obtained The actual layout of the pipeline is modeled in three dimensions, and the paste pipeline transportation is numerically simulated to explore the rheological characteristics of the paste in the pipeline. The results show that: with the increase of the cement sand ratio, the compressive strength of the filling slurry increases; the slurry concentration is an important factor affecting the pressure loss in the pumping process; with the increase of the slurry concentration, the pipeline pumping pressure loss increases; through the numerical simulation analysis, it is shown that the flow velocity at the elbow and corner of the pipe layout is significantly reduced. According to the strength test of tailings slurry, semi industrial ring pipe test and numerical simulation analysis, the best mix proportion of paste suitable for stope filling engineering can be selected.
- 1
Study on Stability Monitoring of Bottom Structure by Natural Caving MethodAbstract:
In order to grasp the stability of bottom structure in the process of mining in real time, microseismic monitoring and stress monitoring technology are used to monitor the ground pressure of bottom structure in Pulang Copper mine. The real time regularity change of the stability of bottom structure during the process of ore extraction is analyzed, the influence of pull-down propulsion and tectonic stress on the stability of bottom structure is studied, and the risk degree of bottom structure instability is evaluated. The results show that the fault structure is the main factor affecting the stability of the bottom structure of Pulang copper mine, and the fault footwall is the area with high degree of ground pressure risk in the mining process. And the untimely and unbalanced ore drawing operation in the poly trough will lead to the stress concentration in the local area of the bottom structure. The stress distribution of the bottom structure can be adjusted by increasing the ore drawing amount. Stress concentration is easy to occur within 45m of the front of the undercutting line, which is the key supporting area that needs to be strengthened.
- 1
Stability Analysis of Rock Wall in Small Clear - distance TunnelAbstract:
Based on the surrounding rock strength criterion, by establishing the force model of the middle rock wall, a discriminant formula for the stability of the middle rock wall of an asymmetric small-distance tunnel is proposed, and the influence of different factors on the ultimate bearing capacity of the middle rock wall is analyzed. The ultimate bearing capacity of the middle rock wall increases linearly with the increase of the buried depth of the tunnel and the prestress of the anchor rod; when laying anchor rods on the middle rock wall, the density of the anchor rods should be controlled to ensure that the bearing capacity is significantly improved; The degree of improvement of the ultimate bearing capacity of the middle rock wall is related to its own cohesive force, which can significantly reduce the plastic zone; the use of bolts and grouting to strengthen the effect is obvious, which can reduce the risk of penetration of the plastic zone. When strengthening, the joint reinforcement should be used. The scope expanded from the top of the tunnel to the bottom of the arch.
- 1
DESIGN AND RESEARCH ON BULK AIR COOLER AT A PLATINUM MINE IN SOUTH AFRICAAbstract:
Working condition acts a very important role in the health and safety of underground mining. Heat stress deteriorates the working condition, influence individual behavior and machine operation in safety manner. Deep mining in South African is leading in the world. Since 1930s the first refrigeration plant started running at the South African gold mine, the air cooling system are broadly used in both gold mines and platinum mines for now, keeping the safe working condition. A platinum mine locates in the well-known Bushveld Complex, which deposits most of the platinum group elements in the world. This mine is accessed by a twin-shaft system, where ventilation system is centralized and open stoping mining method is used. Due to high rock temperature and ambient temperature, the temperature at working areas is more than 40 ℃. The air cooling system must be built for decreasing the temperature in workplaces. Firstly, the hear loading is determined by calculated the heat loading from each resource, and then referred to the practice among platinum mines in South Africa, the Bulk Air Coolers located on surface are selected for this mine. The temperature at each workplace is under the limit since the air cooling system got commissioning. This ensures the mine running well and the temperature in each workplace meets the request in Mine Health and Safety Act.
- 1
Location fingerprint algorithm based on Bayesian fuzzy probability in coal mineAbstract:
Due to the complexity of underground coal mine environment, the positioning accuracy of traditional fingerprint matching algorithm is low in dynamic environment. In this paper, a fingerprint matching location algorithm based on Bayesian fuzzy probability is proposed. The algorithm establishes the reliability mechanism based on the calibration node in coal mine, uses the signal strength received by the calibration node transmitting anchor node to measure the change of wireless channel transmission environment in the area to be located; takes the reliability mechanism of the measured point and Bayesian posterior probability as the input of the fuzzy system, calculates the fuzzy probability as the weight of the reference point, and calculates the coordinates of the measured point. The simulation results show that the positioning accuracy of the fingerprint matching location algorithm based on Bayesian fuzzy probability is about 17% higher than that of Bayesian fingerprint matching positioning algorithm, which can meet the high positioning accuracy of complex dynamic environment in underground mine.
- 1
RESEARCH ON CREEP CHARACTERISTICS OF BACKFILL CONSIDERING CEMENT CONTENTAbstract:
The cemented backfill in the green filling mining method is in a long-term loading environment, and its long-term service performance is related to the safety and stability of goaf. In order to explore the creep deformation characteristics of cemented backfill, uniaxial step loading test of cemented backfill is carried out in this paper. The influence of cement content on creep deformation and failure characteristics of cemented backfill is discussed ,and creep damage constitutive model of cemented backfill which can represent the cement content is established, and the corresponding creep constitutive equation is derived. The results show that: (1) Under long-term load, the cemented backfill has the stages of deceleration creep, isokinetic creep and accelerated creep, but the higher the content of cement, the smaller the instantaneous creep variable and the instantaneous creep rate of cemented backfill, and the time of accelerated creep failure stage will also be delayed; (2) In the process of creep, the elastic modulus of cemented backfill has a nonlinear relationship with creep time and cement content, but its initial elastic modulus is proportional to the cement content; (3) The improved Burgers creep model is in good agreement with the experimental data under different cement contents, which can better describe the creep deformation law of cemented backfill under different cement contents.
- 1
Study on the Stability evaluation and treatment measures of a slope at the Mufu Mountain in NanjingAbstract:
Taking a landslide at the Mufu Mountain in Baotaqiao Street, Nanjing city as subject investigated, the limit equilibrium method and numerical simulation method are used to calculate and analyze the stability of the slope under natural, heavy rain and earthquake conditions before and after slope treatment. The stability calculation and analysis results show that the slope has a small displacement under natural conditions and is in a stable state, and the displacement increases significantly and the stability coefficient decreases under heavy rain and earthquake conditions, and is more obviously affected by heavy rain, and the slope is unstable under heavy rain conditions. After the treatment and reinforcement of slope cutting and load reduction, anchor bolt reinforcement and drainage ditch arrangement, the slope displacement is obviously controlled, and the slope stability coefficient is significantly improved under three different working conditions, and the slope is in a stable state. The slope treatment and reinforcement measures are ideal and achieve the expected treatment effect.
- 1
Research on The Development and Operating Parameters of N2- inhibited Water Mist DeviceAbstract:
The atomization effect of N2-inhibited water mist directly affects its extinguishing and cooling effect in the fire area. In this regard, this experimental study is based on the theoretical analysis of N2-inhibited water mist gas-liquid two-phase flow atomization. The particle size distribution and optimal operating conditions of the water mist under different orthogonal experimental conditions such as air pressure, hydraulic pressure and addition of inhibitors were studied and analyzed. The results show that: ①In the orthogonal experiment of water pressure and air pressure, with the increase of water pressure and air pressure, the overall particle size of the fine water mist is getting smaller and smaller, but under the same flow condition, the increase of water pressure will cause the atomization effect to be poor Ideal, so the particle size distribution is small between 0.2-0.6MPa water pressure and 0.8-1.25MPa air pressure; ②The particle size of fine water mist D90 and D50 show a consistent change trend under different gas-liquid pressure ratio conditions, but After a certain critical value, the rate of change is slow, the air pressure is 1-1.25MPa, and the gas-liquid pressure ratio is 3-4, the size of the fine water mist is 30-50μm; ③Under certain water pressure, whether it contains inhibitors The particle size of the fine water mist decreases gradually with the increase of air pressure. The atomization effect of the composite inhibitor of group C1 is ideal. The best working conditions: air pressure is 0.8-1.0MPa, gas-liquid pressure ratio is 3-4, composite The inhibitor is magnesium chloride: ammonium dihydrogen phosphate = 3:2, the concentration is 20%.
- 1
Development and Design System of Intelligent Muti-funciton Tunnel Robot Based on Digital-twinAbstract:
With the advantages of high speed and precision, industrial robots play an important role in production, and the demand is increasing. However, the development of intelligent multi-functional robot in a confined space such as tunnels is still a gap in China. Based on virtual prototype, the intelligent requirements of tunnel multi-function robot were reconstructed by using intelligent design concept. Finally, through the development of digital twin robot prototype, a complete robot research and development system was established，which was intelligent and multi-functional. The practical application shows that the robot has a remarkable effect on reducing the number of people and improving safety of operation. The research fills the gaps of development for intelligent multi-functional robot in China, provides design basis for development and design of similar intelligent multi-functional robots, and can provide reference for intelligent & efficient development and realization of intelligent digital tunnel in China.
- 1
Numerical simulation of rough crack grouting in cement slurry based on nano-materialsAbstract:
The geometric model of rock rough joint profile was established by independent segmentation method of Hurst index. Based on N-S equation, the grouting seepage of nano calcium carbonate cement slurry in micro-fractures was analyzed. Three groups of grouting pressure and three kinds of cracks with different roughness were set, and their influences on the velocity field, pressure field and filling time of slurry in the cracks were analyzed. The results show that the fracture roughness is positively correlated with the grouting time, while the grouting pressure is negatively correlated with the grouting time. The flow velocity of slurry increases rapidly first and then gradually attenuates to a stable state. The slurry pressure first rapidly attenuates to the minimum and then gradually rises to the initial value. The pressure variation range around 4 mm from the grouting opening is the largest.
- 1
DUST GENERATION MECHANISM AND ITS CONTROL ON OPENCAST MINE ROAD OF SIJIAYING MINEAbstract:
Aiming at a large amount of dust generated from opencast mine road of Sijiaying Mine, theoretical analysis and site experiments were taken to analyze the generation of rock dust on gravel pavement and dust suppression effects of different concentrations of dust suppressants. Studies conclude that cuttings and dust come from tramcars interacting with gravel, gravel and gravel interacting when tramcars pass through gravel road, dust come from pressure and friction between tramcars and these tires, aerodynamic force generated by passing of tramcars, and secondary dust generated by vehicle load and induced airflow, respectively. The influencing factors of mine dust include dust bunnies on road, weather, sprinkling water, vehicle tail gas disturbance, driving load and driving density. Industrial tests are designed and carried out to verify influence of dust adhesion. The test results show that average dust concentration on road after spraying 5% dust suppressant is 1.16mg/m3, which has the best effect. The research results are of great significance to dust control of Sijiaying Mine transportation road.
- 1
Research on the Infiltration Law of Tailings and Its Control Method under RainfallAbstract:
Focused on the harm of the tailings impoundment and the caved rock zone, the feasibility of dry filling the caved rock zone by tailing was studied to overcome the above problems. The experiment of infiltration law for tailing under rainwater was design, and the Rainfall and rainfall intensity as the mainly factor, and the visualization of tailings" changing process was realized by high-speed camera. According to the experimental results, the fitting function of the maximum infiltration depth, rainfall and rainfall intensity was obtained. Based on the experimental results and filed condition, the control method of the high of tailings was higher the maximum infiltration depth in the ten years, Equal amount of drawing ore and decreased block ratio, and the roadway kept arch were raised.
- 1
Experimental Research on Geometric Features of Bubbles Effected by KaolinAbstract:
In order to study of geometric features of bubbles, kaolin and tween 80 are employed to change the properties of liquid phase. The bubbles generated in the system are captured by high speed video and obtained the bubble pictures which are recognized and calculated by software simplePCI to get the features of bubbles. And last, bubble diameter, distribution of bubble diameter, the accumulative probability distribution was employed to analyze the effect of kaolin on bubbles. In the experiment, the concentration of kaolin is 0.5, 1.0 2.0, 4.0 g/L, and the volume concentration of tween 80 is 0.06%. The test show that kaolin and tween 80 changes the surface tension of liquid phase, and the probability distribution of bubble diameter is unimodal in deionized water and the peak center is 7 mm, and kaolin changes the bubble diameter which probability distribution is bimodal and peak center is 6 mm and 3 mm。
- 1
Determination of key parameters of gob-side entry retaining by cutting roof to a inclined thick and hard roof of Dongbaowei coal mineAbstract:
In the Northeast, the conditions of thick and hard roof of inclined coal seams are common. In this study, the calculation formula of roof cutting resistance parameters of thick and hard roof in inclined coal seam is derived by using mechanical theory analysis at the sandstone roof with dip angle 25 and thickness of 14m in Dongbaowei coal mine. It is concluded that the increase of cutting top height can reduce the deformation of surrounding rock, peak pressure of coal side and promote the transfer of stress peak to the peep part of coal wall by using UDEC numerical simulation method. The deformation of surrounding rock decreases first and then increases, and the peak stress of coal side moves to the deep with a weak change when the increase of cutting angle. We derive the formulas for the height and the angel of cutting roof by using the stability principle of surround rock. The research results are comprehensively applied to the project, and the parameter design values of the cutting roof height 7.4m, the roof cutting angle 20, the blasting parameter charge structure 4+4+2, the support resistance in the roadway 2741kN, and the value of the zoning support range are determined. The research results are applied to the field, and the roadway retention is well formed, which can provide a useful reference for the design and application of roof cutting and roadway under similar conditions.
- 1
APPLICATION OF OUTBURST WARNING SYSTEM BASED ON GAS MONITORING DATA SOURCE IN XIAYUKOU COAL MINEAbstract:
In order to realize non-contact and continuous early warning of coal and gas outburst risk in heading face of Xiayukou coal mine, a set of outburst early warning system integrating database, server, client and information release platform was established based on gas monitoring data source. Through statistical analysis, the early warning sensitive index and critical value in accordance with the gas emission characteristics of Xiayukou coal mine were determined. The application results showed that: the early warning system can realize on-line monitoring, real-time early warning and timely distribution of early warning results for the outburst risk of driving face, and capture the coal and gas outburst risk in advance for many times, and the overall early warning accuracy rate reaches 84%. The application of early warning system not only significantly improves the accuracy and effectiveness of outstanding prediction, but also further compels the foundation of mine intelligent construction.
- 1
Study on In-situ Stress of Phosphate Rock Mining Based on ANSYS / LS-DYNAAbstract:
In order to accurately detect the location of the peak in-situ stress in front of the mining area and reduce the safety accidents caused by mine dynamic disasters. Based on ANSYS/LS-DYNA, the whole model of phosphate rock is established. In ANSYS/LS-DYNA, the change of stress value of phosphate rock in the direction of roadway and the change of stress value of phosphate rock caused by different mining length are studied when the length of mining roadway is 2.5m, 3.5m, 4.5m and 5.5m. The results show that the stress of sandstone has more influence on the internal stress wave velocity than that of phosphate rock, and the stress of sandstone and phosphate rock has more influence on the internal stress wave velocity. The results show that the stress value of phosphate rock in the direction of tunnel in ANSYS/LS-DYNA increases to a certain value and decreases gradually. When the mining length is 3 m, the stress change of phosphate rock increases. The change trend of stress of sandstone and phosphate rock to their internal stress wave velocity is basically the same. Finally, the conclusion that the maximum stress of phosphate rock obtained by ANSYS/LS-DYNA is about 8m away from the current position is verified. The results of the study provide a preliminary research basis for the prevention of safety accidents caused by mine dynamic disasters in the mining process.
- 1
Effect of flocculant type on the thickening property of superfine tailingsAbstract:
In order to speed up the settling of superfine tailings and reduce the turbidity of supernatant, finding a flocculant matching rule. Taking ultra-fine tailings and different kinds of flocculants (PAM) of a lead-zinc mine as experimental materials, the indoor static thickening test was carried out, and the effects of the flocculant ion type and flocculant molecular number on the flocculation effect were studied respectively. Through the test results, the flocculant selection rules of ultra-fine lead-zinc tailings were obtained. The results show that the flocculation effect of flocculants：non-ionic＞cationic＞anionic. The thickening effect of non-ionic flocculants is 66.3% higher than that of anionic flocculants. With the molecular number of flocculants, the turbidity of supernatant decreases; the molecular number of flocculants increases from 10 million to 16 million, the sedimentation rate of tailings particles increases and the underflow is concentrated. If the molecular number of flocculant continues to increase to 20 million, the sedimentation rate will be slowed down and the underflow concentration will be smaller.
- 1
FAILURE MECHANISM AND SUPPORT OPTIMIZATION OF SURROUNDING ROCK IN FAULT CROSSING TUNNELAbstract:
In view of the phenomena of severe roof subsidence, serious internal extrusion of two sides and large floor heave in the fault tunnel of pump house and substation in a deep mine, through site survey, numerical simulation and in-situ monitoring, the deformation and destruction mechanism of wall rock under the primitive support plan was analyzed, and the bound support scheme of high-strength bolt and grouting anchor cable is proposed. The results show that deep high ground stress, fault local stress concentration and shear slip failure, insufficient support strength are the main causes of wall rock deformed and failure. grouting anchor cable can control the scope of wall rock fragmentation zone with effect, combined with high-strength bolt to mobilize deep surrounding rock to form stable supporting structure. Combined with field displacement monitoring, it is found that the discontinuous deformation control of tunnel passing through fault location is controlled The overall deformation is greatly decreased, and the stress level of wall rock is ameliorated.
- 1
Research on Point Cloud Registration Algorithm Based on ISS-SHOT+3D-NDTAbstract:
Aiming at the problems of low coarse registration matching rate, long registration time and low precision of precise registration in the previous registration process of point cloud data, this paper proposed a point cloud registration algorithm combining ISS SHOT and 3D-NDT.First of all, using the internal shape descriptor (ISS) algorithm to the sampling point cloud data to extract the feature points, and to extract the feature points in the direction histogram descriptor (SHOT) is described, and the similarity function is used to change the corresponding feature points to match, and then use LMeds algorithm to delete 2 slices matching error of feature points and complete the coarse registration of point cloud data, achieve good initial registration position and attitude.Finally, 3D-NDT algorithm is adopted to conduct spatial voxelization for the point cloud data after rough registration, and probability distribution function is used to complete accurate registration of point cloud data.Experimental results show that compared with other point cloud data registration algorithms, THE ISS-shot +3D-NDT algorithm not only improves the registration accuracy of point cloud data, but also improves the registration efficiency.
- 1
Experimental Study on Mineral Processing of a fine-grained copper-zinc-iron polymetallic oreAbstract:
A polymetallic ore contains 0.38% copper, 4.96% zinc and 23.34% iron, chalcolite and sphalerite as the main minerals have fine mosaic size , and they are intercalated densely impregnated and distributed. In order to efficiently recover the useful minerals in the ore, a systematiclly experimental study on mineral processing was carried out. Combined with the ore properties and the natural floatability of sulfide minerals, the process which contain copper preferential flotation, zinc-sulfur mixed flotation and separation, and recovery of magnetite from flotation tailings by magnetic separation was determined.Through closed circuit test, The copper concentrate with 21.92% grade and 62.66% recovery can be obtained, the Zinc concentrate with grade 47.36% and recovery 63.28% can be also obtained. After the flotation tailings are subjected to magnetic separation followed by flotation desulfurization , Magnetite concentrate with grade 60.05% and sulfur content 0.52% can be obtained. At the same time, the valuable elements of silver and indium in the ore are also well enriched in the copper and zinc concentrate,which provides technical support for the industrial development of the ore.
- 1
Research on Risk Evaluation of Overseas Mineral Investment Activities in Eastern Countries——Take overseas gold mining investment as an exampleAbstract:
In order to scientifically evaluate the host country risks faced by Chinese-funded enterprises in overseas mineral investment, Yunwuyuan theory was introduced to construct a host country risk evaluation model for overseas mineral investment activities. Through the identification of the host country risk of overseas mineral resources investment, the risk evaluation index system of overseas mineral investment activities in the host country was established. The combination weight was determined by the comprehensive use of analytic hierarchy process and entropy method, and the cloud model and matter-element theory were combined to construct overseas mineral resources. Risk assessment model for host countries in resource investment activities. The model has been applied to verify the application of 8 countries with relatively concentrated investment and relatively rich gold mineral resources. The evaluation results are consistent with the actual location selection of overseas gold mineral investment by Chinese-funded enterprises, indicating that the model has scientific validity and can be used for my country’s mineral resources. Provide reference for the location selection of enterprises" overseas investment.
- 1
Mechanism of early hydration of alkali-activated binder controlled by limeAbstract:
In order to improve the comprehensive utilization rate of solid waste and elucidate the mechanism of early micro-modification of alkali-initiated cementitious material controlled by lime, the alkali-initiated cementitious material was prepared with slag, steel slag and desulfurized gypsum as the main raw materials. Based on the exploratory optimal test conditions of slurry mass fraction 70%, sand-cement ratio 6, slag: steel slag: desulfurized gypsum: lime = 42:40:12:6, the net slurry test was carried out, and the microscopic analysis means such as X-ray diffractometer, fourier transform infrared spectrometer and scanning electron microscope were used to explore the mechanism of early hydration of slag-slag-gypsum composite gelling system controlled by lime. The research results show that: the hydration products of slag-based alkali-excited cementitious materials of different ages are mainly calcium alumina and C-S-H gels, lime provides a higher pH value for the hydration system, and the slag continues to hydrolyze under the action of OH-polarity.
- 1
Study on the thickening properties of tailings with different physical propertiesAbstract:
In order to study the influence of physical properties of tailings on the thickening performance of tailings, the median particle size, restricted particle size, average particle size and density of tailings from 10 typical mines were measured, and the tailings from these 10 mines were tested for flocculation sedimentation. The test results show that: the underflow concentration and the best flocculant dosage of the mortar have nothing to do with the density of the tailings, but they are related to the tailings particles. The finer the particle size of the tailings is, the lower the underflow concentration is, and the more flocculant dosage is required for the settlement test. The relationship equation between the median particle size of the tailings and the underflow concentration, and the relationship between the limiting particle size of the tailings and the concentration change are obtained by regression analysis. The error between the predicted value and the test value is less than 3% when the research results are applied in a metal mine. It is proved that the relationship equation derived in this paper is convenient and feasible, and has a good popularization and application value.
- 1
PORE DETECTION METHOD OF ROCK AND SOIL BASED ON COMPUTED TOMOGRAPHYAbstract:
The pore structure characteristics of rock-soil mass play a vital role in its engineering geological properties. Its microstructures are always characterized by the Computed Tomography (CT) scanning technique regarded as a nondestructive testing technology. Owing to the fact that the pore structures of the rock-soil mass cannot be directly reflected by the gray images obtained from CT scans, its identification in grayscale images is very indispensable. However, common identification methods perform poor accuracy and stability when processing CT images with uneven gray distribution. In this study, an adaptive threshold segmentation method based on edge detection (LTE method) was proposed to comprehensively consider the grayscale distributions and grayscale gradient variations in CT images, calculate the corresponding gray thresholds in different domains of the CT images, and then precisely identify the pore structure in accordance with the local threshold. Considering that the pore structure of loess is staggered, complex, and difficult to identify, CT images of the loess were selected as the test samples. In addition, the maximum entropy, OTSU, Sobel edge detection, and the LTE method were adopted to recognize the pore structure characteristics of loess, and then reconstruct the three-dimensional pore structures of the loess according to the different identification results. Based on above three-dimensional pore structures, numerical simulations in different directions and laboratory tests of loess permeability were conducted. By comparing above two tests, it is found that the LTE method can effectively evade the under-segmentation and over-segmentation problems existing in other pore identification methods and reflect the anisotropic permeability of rock or soil mass more realistic. All the results indicate that the LTE method can effectively identify the pore structure characteristics of rock or soil mass, provide accurate and reliable basic research data for quantitatively analyzing pore structure characteristics of rock-soil mass and numerically simulating rock-soil mass.
- 1
Stability analysis of large abandoned soil field under unsaturated seepage action under different rainfall conditionsAbstract:
For the study of unsaturated soil conditions of rainfall infiltration and soil stability problem, a soil field in yunnan as an example, according to the geological exploration data, and soil field obtained on the basis of field experiment and indoor experiment data use GeoStudio software, using VanGenuchten (VG), to simulate the model analysis under the condition of different rainfall intensity and soil pore water pressure and saturation, the change of the data such as safety coefficient.In the abandoned soil site, the rainfall intensity is large, the rainfall duration is long, but the evaporation is large, so all the soil layers in the slope body present unsaturated condition.This paper intends to set up five different rain strong seepage analysis models to analyze the changes of slope soil moisture content, pore water pressure, soil-water characteristic curve, transient saturation area change and slope stability safety factor data under the same condition of rainfall duration.Data results show that at the beginning of the rainfall, rainfall intensity for the slope safety factor, after 6 hours, rainfall on slope surface soil pore water pressure, saturation continues to rise, and gradually formed the transient saturated zone, rainfall duration exceeds 12 hours later, due to the increasing permeability coefficient, the matrix suction between soil particles gradually decline, surface soil moisture content is close to saturation, the formation of surface runoff, and converge in platform is the first step on the slope formed small groove, late rains, the soil and soil field most close to the saturated moisture content, the permeability coefficient is no longer growth, matrix suction not abate, flattening of the safety coefficient of stability decline rate;According to the analysis of minimum safety factor and soil water parameter after rainfall, the abandoned soil field is determined to be stable.
- 1
Preparation and characterization of high-efficiency permeability enhancerAbstract:
To improve the effect of coal seam flooding, a kind of permeable augmentation agent was prepared based on graft copolymerization theory. The relationship between sodium alginate, acrylamide, water volume, potassium persulfate, N, N '-methylene diacrylamide, and temperature was investigated by viscosity experiment. The wettability, permeability and dust removal effect of the additive were studied. The results show that the contact Angle and permeability of the augmentation agent are better than water. In the quantitative test of dust removal effect, it can also be clearly concluded that the coal soaked by the permeating agent has the best ability to retain coal dust when it is broken, and the reason for the good dust removal effect is verified by scanning electron microscope observation.
- 1
Numerical simulation of backfilling slurry flow field in composite mixing structureAbstract:
In the process of mine backfilling, forced mixing is often used to promote the dispersion of cementitious materials and improve the fluidity of slurry. The effect of mixing has an important influence on the filling quality. In this paper, fluid simulation software is used to simulate the internal flow field of a new type of vertical mixing tank, and the effect of "double impeller & screw belt" compound mixing structure is verified. The results show that the optimum blade installation angle is about 60°. Compared with simply increasing the size of blades, the composite mixing structure can make the internal filling slurry convective movement more efficient, effectively eliminate the low-efficiency mixing zone, and meet the continuous preparation requirements of the backfilling slurry.
- 1
Experimental study on true triaxial Rock burst of deep rock under different disturbance conditionsAbstract:
In order to study the deformation and failure characteristics of deep engineering under different disturbances, this paper takes a deep ore granite as the research object, the QKX - YB200 servo rock true triaxial test instrument, the sample under two different dynamic disturbance (four axis pressure level), under it’s "static load + dynamic disturbance" destructive test of surrounding rock, and the system studied the mechanical properties of specimens under different disturbance conditions, damage and acoustic emission characteristics. The results of the study show that there is a threshold for rockburst in the sample under dynamic disturbance (the axial static stress ratio is 90%), when the axial stress is less than the threshold, sample disturbance does not occur, And when the axial stress exceeds this threshold, rockburst occurs quickly, and as the axial pressure continues to increase, the frequency and damage of rockburst increase. Under the same "external conditions" (pre-static load), the occurrence of rock bursts in the specimen is significantly affected by different dynamic disturbances, and it is easier to induce rock bursts under irregular disturbances. Under other conditions unchanged, add 3% axial static stress to the specimen. Under sine wave disturbance, the energy of the specimen during rockburst increases from 1.89×1011aJ to 4.17×1011aJ, and the energy of the specimen during rock burst under the disturbance of seismic wave increased from 7.07×1010aJ to 2.06×1011aJ, indicating that the specimen was more affected by axial pressure under the disturbance of seismic wave, and the disturbance of seismic wave was more likely to induce rock burst. Therefore, for deep engineering, suitable controlled blasting technology should be adopted to reduce disturbance energy, which is of great significance for underground rock burst prevention.
- 1
Study on the movement and fracture evolution of overburden in bauxite mining of valley landformAbstract:
In this paper, the 880m level of bauxite mining area I in boduhe is taken as the research object. Aiming at the engineering problem that the direct roof is unstable and the indirect roof is a strong karst aquifer, the research method of theoretical analysis, numerical simulation is comprehensively used to study the law of overburden movement and fracture evolution in the mining process of the ore bearing layer. Theoretical analysis indicate:That the landform of bauxite mine in boduhe river is characterized by the landform of middle and low mountain valley on the plateau, and the hydro-geological conditions of the mining area are complex, and the direct roof of the ore bearing bed is unstable. Numerical simulation indicate:The vertical stress is small The vertical displacement of the direct roof and the basic roof of the orebody show the settlement characteristics of "W" and "V" respectively. The vertical displacement of the direct roof is more obvious than that of the basic roof.Through the simulation of the evolution law of the overlying rock fracture in the mining without support, the development trend chart of the fracture zone is obtained, and the maximum development height of the fracture zone is determined to be 46.85m by the discrete element method. The research results of this paper provide theoretical support and guidance for the technical measures adopted by the Boduhe bauxite mine, and also provide reference and experience for mining under similar conditions.
- 1
EXPERIMENTAL STUDY ON THE COMPRESSIVE PROPERTIES OF DIFFERENT CEMENTS IN CEMENTED BACKFILLSAbstract:
In order to explore the influence of different cements as cementing agent on the strength of the backfilling body, a series of unconfined compressive strength tests with cement type, mortar-to-sand ratio, mass concentration and curing age as the influencing factors and uniaxial compressive strength as the evaluation index were performed. The sensitivity of each factor to uniaxial compressive strength of the cemented backfilling body was studied through the visual analysis of range and variance analysis. The results show that the influence order is cement type>age>lime sand ratio>mass concentration, and the strength of backfiling body with P.O52.5 as a cement is the largest, and that of P.S32.5 is the smallest; Analysis of variance shows that the ratio of lime to sand and age have significant effects on compressive strength, and the mass concentration of backfill slurry has the least impact on backfills; Finally, the market prices of common cement types are summarized. According to the actual filling requirements of the mine, an economical filling plan that meets the strength requirements can be formulated.
- 1
Research on Coal Mine Safety Management Level Evaluation Based on AHP-DEMATELAbstract:
In order to scientifically and reasonably evaluate the safety management level of coal mines, combined with the characteristics of the coal industry, coal mine safety shall be constructed from five levels: safety management concept and cultural level, miner safety level, mechanical equipment safety level, safety education and training level, and management information system level. Management level evaluation index system. The comprehensive analysis and calculation of factors affecting the safety management level of coal mines are carried out by using two methods: Analytic Hierarchy Process (AHP) and Decision Test and Evaluation Laboratory (DEMATEL), which solves the problem of the lack of single weighting of indicators. The results found that three factors, including safety behavior culture, safety awareness of miners, and safe mining technology, have the highest comprehensive influence. Among them, the comprehensive influence of safety awareness of miners reaches 0.1725, which has the most significant impact on the safety management level of coal mines.The research results of this paper can provide reference for managers to propose corresponding countermeasures from these aspects to improve coal mine safety management level.
- 1
RESEARCH ON REASONABLE PILLAR MALPOSITION DISTANCE BASED ON OVERBURDEN AND SURFACE SUBSIDENCE IN SHALLOW BURIED CLOSELY SPACED MULTI-SEAMS MININGAbstract:
In order to obtain overburden and surface subsidence in shallow buried closely spaced multi-seams mining, taking shallow buried closely spaced multi-seams mining in Ningtiaota coal mine as background, combining with engineering examples statistics, physical simulation and numerical calculation, overburden and surface subsidence with different pillar malposition distance is revealed, and the reasonable pillar malposition distance to decrease surface uneven subsidence is obtained. The research results show that the subsidence coefficient and velocity of repetition mining are larger than single seam mining. Surface subsidence is affected by mining height, interval distance and pillar malposition distance. Surface uneven subsidence can be decreased through reasonable pillar malposition distance. Subsidence coefficient obtained by physical simulation, numerical calculation and site analysis are 0.77, 0.76 and 0.74 respectively. When the pillar malposition distance is less than 10m, surface subsidence fall distance is the largest, which is 0.83 times of the lower mining height. With the pillar malposition distance increases, surface subsidence fall distance decreases gradually, when the pillar malposition distance is lager than 40m, surface subsidence fall distance is the least and tends to stable, which is 0.6 times of the lower mining height, the uneven subsidence decreases. It can provide pillar malposition distance determination method based on overburden and surface subsidence characteristics.
- 1
Study on the effect of mixing water on coal mine filling paste performance under pH-T coupling conditionsAbstract:
In order to study the influence of hydration environment on the performance of coal mine cemented paste backfill (hereinafter referred to as paste), this experiment uses three kinds of temperature (5 ℃, 15 ℃, 30 ℃) and three kinds of pH (4, 7, 10) to mix water to prepare paste. Through the experiment of the paste setting time and the uniaxial compressive strength (hereinafter referred to as the strength) under different periods under standard curing, combined with scanning electron microscope (SEM) to explore the change law of paste performance under the combined action of pH-T. The results showed that: in terms of setting time, the setting time of paste under neutral or weak alkaline conditions shortened with the increase of temperature; under weak acid conditions, the setting time was first shortened and then extended with the increase of temperature. In terms of strength, the strength of the paste under weak acid and low temperature conditions is positively correlated with the curing age. When the temperature is lower than 30 ℃, the strength of the paste first increases and then decreases as the temperature rises and the age increases; The strength of the paste under neutral conditions increased with the increase of temperature and age; the strength of the paste under weak alkaline conditions decreased with the increase of temperature and age.
- 1
Effects of different physical improvement methods on water and nutrients of mining associated clayAbstract:
the surface soil of the waste dump of the open-pit mine in the eastern grassland is insufficient, and the mining associated clay is difficult to promote the vegetation construction due to the poor physical structure and low effective nutrients, so it is necessary to improve the mining associated clay, and analyze the possibility of using the mining associated clay as the surface soil alternative material. In this study, according to the local actual situation, the sand soil which is easy to obtain is selected to improve the mining associated clay physically. It is found that the physical improvement process should be full mixing of sandy soil and clay soli. The water infiltration rate of mixed soil is the most similar to that of topsoil, and it is 2.74 times of that of clay, which can effectively prevent water accumulation; At the same time, the control ability of the mixed physical improvement process to the potassium element migration is most similar to that of the topsoil. It is determined that 1:1 is the best ratio, and the soil matrix after mixing is sandy clay, which is the most similar to the surface soil - loamy clay in the soil triangle; Through the experiment of water evaporation, it is found that the effect of 1:1 ratio is better than other mixing ratio. Therefore, using sand to improve the mining associated clay has the potential to become the surface soil substitute material of the open pit waste dump, promoting the utilization of clay resources and the ecological restoration of the waste dump.
- 1
Extremely Soft Broken Non-Metallic Minerals Safe,Low Dilution Loss And Pollution-free Filling Mining MethodAbstract:
The texture of talc is soft and broken, the higher the whiteness, the higher the value. Most of the ground mining methods of talc mine are slicing and caving method, which is easy to cause surface subsidence and poor safety conditions. With the tightening of national mining policy and the promotion of filling mining, many talc mines will change their mining methods. Based on the engineering background of a talcum mine from caving method to filling method, this paper puts forward downward slicing wall filling mining method. This method adopts drift mining method and draws lessons from the horizontal short wall mining idea in coal mines. Without the traditional one-step-two-step stope, the adjacent approach is always mined continuously in one direction. By constructing artificial false roof and erecting the side filling retaining wall along the length direction of the access road, a new method is proposed In addition, waterproof nylon cloth is laid inside the retaining wall and the bottom of the goaf of the approach road to avoid the leakage of filling slurry polluting the whiteness of talc, thus reducing the sales value of talc. The research results can realize the safe, low lean loss and pollution-free filling mining of talc mine, and can be used for reference and guiding production of a large number of soft broken rock and non polluting non-metallic mines.
- 1
Numerical simulation of mechanical characteristics of roadway surrounding rock based on dynamic load strength under superposition of dynamic loadAbstract:
In order to study the mechanical characteristics of floor roadway surrounding rock under different strength superimposed dynamic load, taking 879 gas drainage roadway in Ⅱ 5 mining area of Zhuxianzhuang Coal Mine as the engineering background, numerical simulation software FLAC3D was used to study the stress, displacement and plastic distribution of roadway surrounding rock under different strength superimposed dynamic load. The results show that: with the increase of disturbance intensity, the stress concentration coefficient of roadway increases in the form of irregular harmonic motion waveform, the stress concentration degree of roadway roof and floor and two sides increases, and the peak position shifts to the deep surrounding rock; the deformation of roadway roof and two sides increases with the increase of disturbance intensity, and the change rate of right side is the largest, followed by roof and left side When the disturbance strength is less than 40 MPa, the increment of plastic yield mesh number of surrounding rock is 0.2/MPa, and when the strength is greater than or equal to 40 MPa, the increment of plastic yield mesh number is 0.6/MPa.
- 1
Experimental study on the effect of mixed aggregate gradation on rheological properties of filling paste with different concentrationsAbstract:
In order to clarify the effect of mixed aggregate ratio and particle size gradation on the rheological properties of different concentrations of filling paste slurries, coal gangue and river sand (referred to as "gangue sand ratio") are used as the characteristics of different aggregate particle sizes. Analyze, carry out rheological tests under different aggregate ratios and different concentrations, and obtain rheological parameters and rheological characteristic curves through Bingham model conversion. The test results show that the ratio and concentration of the mixed aggregate affect the fluidity of the slurry. The relative plastic viscosity coefficient and the relative yield stress increase with the increase of the concentration, the relative plastic viscosity coefficient increases with the proportion of river sand, and the relative yield stress increases with The increase in the proportion of river sand changes in an "N" shape; when the proportion of river sand in the mixed aggregate is greater than that of coal gangue, the relative plastic viscosity coefficient increases significantly, and the relative shear stress first decreases and then increases. Appropriately increasing the content of fine particles can reduce the transportation resistance of the slurry, and the mixed aggregate gradation has a certain degree of influence on the rheological properties of the slurry.
- 1
FLOTATION SEPARATION OF FELDSPAR FROM QUARTZ AND STUDY ON THE MECHANISM OF COMBINED COLLECTORSAbstract:
Fluoride free flotation separation of feldspar and quartz is always a difficult problem in mineral processing. The effective separation of feldspar and quartz can be achieved by using mixed collectors composed of oleic acid and dodecylamine at pH = 2. The mechanism study shows that when pH = 2, the feldspar surface is electronegative, which can strongly adsorb the cation of dodecylamine through electrostatic interaction, while quartz surface is positively charged and does not adsorb with dodecylamine. Oleic acid molecules and dodecylamine ions form molecular-ion association complexes at this pH, which reduces the surface tension, HLB value and CMC value of dodecylamine ion, thus improving the hydrophobicity and collecting ability of dodecylamine. The infrared spectrum data show that the adsorption capacity of the combined collectors for feldspar is stronger than that of single collector, but it is not valid for the adsorption of quartz.
- 1
Research on Development and Application of Steel Slag-based Consolidation Powder Filling Cementing MaterialAbstract:
Aiming at the problems of low cement strength and high cost of cementitious materials in the ultra-fine full tailings filling method of Zhongguan Iron Mine of Hegang Mining, the use of steel slag, slag and desulfurized gypsum solid waste resources to develop steel slag-based consolidation powder filler Condensable materials research. First, analyze the physical and chemical characteristics and quality evaluation of the solid waste materials of steel slag, slag and desulfurized gypsum that can be used in the mine. Then, carry out the orthogonal test of the strength of the tailings solid waste cemented powder cemented backfill and the research on the rheological properties of the tailings filler slurry. The test results show that the influence of desulfurized gypsum on the 7d strength of the cement is greater than that of steel slag powder, and the influence of steel slag powder on the 28d strength of the cement is greater than that of desulfurized gypsum. In view of mine requirements for cement strength and rheological properties of filler slurry, the optimized formula of steel slag-based consolidation powder cementitious material is determined as follows: steel slag 30%, desulfurized gypsum 10%, and slag 60%. Finally, based on the cement-sand ratio of 1:4 and the mass concentration of 64%, the strength of the cemented filling body was carried out. The 7d and 28d strength of the filling body reached 1.98MPa and 3.3MPa, respectively, which met the requirements of the mine for cemented filling strength. The cost of consolidated powder and cementitious materials is 38% and 28% lower than that of 42.5 cement and cement-solid powder, respectively. At present, the steel slag-based consolidated powder cementitious material developed by this research institute has carried out industrial filling tests in Zhongguan Iron Mine, thus promoting the application of green filling cementitious materials in iron mines.
- 1
STUDY ON MINING CONTROL EFFECT OF SUPERHIGH WATER BACKFILLING MINING IN DEEP COAL SEAMAbstract:
The deep coal reserves and the buried coal amount in China"s mining areas are huge. When mining deep coal seams, the occurrence environment of "three high and one disturbance" causes surface collapse, intense mine pressure, impact ground pressure and other mining disasters, affecting the safety of ground buildings and the ecological environment of the mining area. In order to solve the mining damage in the deep coal seam mining, the superhigh water filling mining technology is adopted to control the mining damage. Through numerical simulation and field experiments, the mining control effect of superhigh water backfilling mining is studied. The results show that the higher the backfilling rate is, the better the damage control effect is. When the backfilling rate reaches 90%, the accumulated maximum subsidence of the surface is 0.198 m, the maximum working resistance of the hydraulic support is 35.1 MPa, the average periodic weighting step distance is 35.6 m, and the maximum accumulated energy in the coal seam is 6456.54 J. When the deep coal seam is backfilled with superhigh water, the effect of surface subsidence reduction is obvious. When the pressure is applied, the mine pressure is significantly reduced, and the step distance of pressure is significantly increased. The effect of rockburst prevention is good.
- 1
Development of purification of low-grade magnesite by flotationAbstract:
The characteristics of low-grade magnesite resources in China are briefly described. The common flotation process of magnesite is introduced. The new achievements in flotation reagents, flotation interaction theory and molecular simulation technology in recent years are emphatically reviewed. The analysis shows that the efficient separation of low-grade magnesite can be realized by optimizing the design of flotation process and the development of highly selective cationic collector; the flotation interaction theory and molecular simulation technology provide a new way for exploring the adsorption nature of reagents and minerals in the flotation system of magnesite. It is pointed out that attention should be paid to the research and development of green beneficiation process and flotation reagents in the future. Meanwhile, molecular simulation technology should be used to promote the continuous improvement of the theoretical system of magnesite flotation and improve the utilization efficiency of low-grade magnesite resources.
- 1
Analysis on Supply and Demand Situation of Indium Resources and Mining Policy in JapanAbstract:
With the development of high-tech industry and modern information industry, indium, as an important raw material, has increasingly become a strategic resource for fierce competition among countries. Japan is the largest consumer of indium in the world and a country with relatively perfect indium mining policies. This paper analyzes the supply and demand situation of indium resources in Japan, analyzes the supply situation of indium in Japan from primary indium, recycled indium and imported indium. It is found that the supply of indium in Japan is relatively stable and the indium industry is in a good state of security. Then this article analyzes Japan''s indium mining policy from three aspects: Japan"s metal indium reserve policy, indium exploration policy and indium resource recovery policy. Finally, this paper put forward some suggestions on the development of indium industry in China.
- 1
STUDY ON THE INFLUENCE OF SUPERCRITICAL CO2 AT DIFFERENT TEMPERATURES ON SHALE MECHANICAL PROPERTIESAbstract:
The geothermal temperature of shale gas reservoirs in southwest China is usually above 60 ℃. The current research frontier is to use supercritical CO2 to improve its extraction efficiency. Therefore, the experimental simulation of supercritical CO2 acting on shale at different temperatures was carried out to analyze the changes in its mechanical properties, and the mechanism of supercritical CO2 acting on shale at different temperatures was discussed.As soaking temperature and soaking time grew, shale tensile strength and triaxial compressive strength and elastic modulus are different degrees of weakening, the tensile strength loss rate of the largest, the three kinds of negative exponent, mechanical parameters and the soaking time soaking temperature accelerated shale weakening speed plays a main role in the early immersion.Preliminary analysis shows that soaking temperature by improving the dissolution speed increase shale mineral dissolution, and thus increase shale porosity and decrease the cementation strength, by raising the temperature of shale swelling, also promote the formation of microcracks, soak time by cumulative dissolution degree of shale mineral dissolution, on the other hand through shale adsorption CO2 expansion cumulative growth, promote the micro crack initiation, shale mechanical properties and degradation.
- 1
Experimental Comparison of Tailings Filling Materials before And after Fine Grained Tailings LossAbstract:
In order to study the filling characteristics of tailings after fine-grained tailings loss during actual filling,Taking 8% of fine-grained loss in cemented filling of open stope and tailing in Huanggang mining I mining area as the experiment background,The basic physical properties and particle size composition of underflow tailings were measured, and the natural settlement, bleeding, slump and block strength ratio tests were carried out, and the test data were compared with the test data of unclassified tailings. The results show that: the nonuniformity coefficient of underflow tailings is smaller than that of full tailings, but the degree of nonuniformity is still good, and it is easy to compact;The natural settling speed of underflow tailings is much faster than that of full tailings, and the coarse particles have settled to close contact after 10 minutes;On the contrary, the bleeding rate of underflow tailing slurry with high concentration is higher than that of unclassified tailings slurry with lower concentration. The water retention effect of underflow tailings is relatively poor, the slump is higher, and the transportation performance is better;Under the same conditions, the strength of underflow tailings is higher than that of full tailings, and the loss of fine particles is beneficial to improve the strength of filling body.Combined with the test results, it is recommended that the best lime sand ratio of stope filling slurry with first step and second step is 1:10 and 1:15 respectively, and the concentration is 80% ~ 82%.
- 1
Coking coal flotation and its kinetics using a coal tar-based collectorAbstract:
In this study, the supernatant mixture of diesel and coal tar extract was used as a novel coal tar-based collector for Xinjiang coking coal flotation, and the flotation recovery and kinetics using diesel and coal tar-based collector were compared. Flotation results showed that the coal tar-based collector can effectively improve the yield of clean coal, increase the separation efficiency index and flotation rate without significant changes in the ash content of clean coal. The contact angle tests revealed that the coal tar-based collector enhanced the hydrophobicity of coking coal surface. Fourier transform infrared spectroscopy results showed that the coal tar-based collector contains more aromatic compounds and oxygen-containing functional groups than diesel. These aromatic compounds and oxygen-containing functional groups can bond with aromatic compounds on the coal surface through hydrogen bond and π-π stacking interaction, which increased the number of hydrophobic sites of coal surface and finally enhanced the floatability of coking coal and flotation rate.
- 1
Mining Method Optimization Model and Application Based on Game Theory Combined Weighting -TOPSIS MethodAbstract:
Optimization of mining method is one of the most important decisions in mining enterprises. In order to solve the problem of mining method optimization for a silver mine with sharp tilt broken medium thick ore body, a method optimization model based on game theory combined weighting-TOPSIS method is proposed to optimize four primary mining methods. Firstly, 10 evaluation indexes are selected from three aspects of economy, technology and safety to construct the evaluation index system; secondly, the subjective and objective weights obtained by G1 method and entropy weight method are combined to obtain the comprehensive weight through game theory; finally, TOPSIS method is used to calculate the relative nearness degree of the four primary schemes, which is 0.871, 0.649, 0.132 and 0.423 respectively. So the method 1 is the optimal mining method, which is consistent with the engineering practice, indicating that the evaluation model has a certain guiding significance for the optimization of mining methods.
- 1
Research on Longitudinal Vibration and Heave Compensation of Lifting Pipe in Deep Sea MiningAbstract:
The dynamic equilibrium equation of lifting subsystem is established, and the motion differential equation of heave compensation system is derived. Wilson-θ method is used to analyse the time domain response of piping system. Based on MATLAB/Simulink and ABAQUS/Aqua module, the dynamic characteristics of the lifting pipe are studied. The results show that the longitudinal vibration amplitude of the lifting pipe is small at the top and large at the bottom, and the maximum amplitude occurs at the buffer. The vibration response of the lifting pipe will be delayed, and the delay time from top to bottom is longer and longer. The maximum axial force of the lifting pipe occurs at its top, and the axial force will oscillate at the initial stage of vibration. The heave compensation system can effectively improve the oscillation and reduce the excitation displacement at the top of the lifting pipe. Under the sea state of level 4 and 6, the excitation displacement at the top of the lifting pipe decreases by 51.49% and 31.39%, and the amplitude at the buffer decreases by 51.55% and 31.54%, respectively.
- 1
Study on the Activation Stirring Mechanism of Filling slurry and Its Influencing FactorsAbstract:
The efficient activation preparation of filling slurry in the mine filling process is the key to achieving high-quality filling. Aiming at the filling slurry with flotation tailings as aggregate, its activation and stirring mechanism was analyzed, and the effects of stirring speed, stirring time and material composition on the stirring quality were studied. The results show that, in addition to the basic convection, diffusion, and shearing motions in the mixing process of the filler slurry, the activity of the slurry is also related to the chemical reaction generated under the action of mechanical force; the shear rate generated by the mixing blade during the mixing process a good activation stirring effect can be achieved at about 400s-1; when the stirring time is less than 120s, as the stirring time increases, the quality of the slurry also increases. When the time exceeds 120s, the fluidity and strength are no longer obvious .When the material ash is relatively small and the material concentration is low, it is beneficial for activation and mixing; the finer the tailings, the more activation and mixing are required. The activation and mixing can also reduce the amount of cement.
- 1
Research on the influence of additive on strength and microstructure of backfillAbstract:
In order to improve the strength of filling paste and accelerate the moving frequency of hydraulic support, the mechanical strength, hydration products, microstructure and reaction mechanism of filling paste with different contents of calcium sulfate were tested and analyzed. The results show that the filling paste specimen with different gypsum content has different peak strength with curing time. When the specimens were cured for 28 days, the peak strength of the filling paste with 0.5% gypsum content was the largest, which was 4.98MPa; the peak strength of the filling paste with 3% gypsum content was the lowest, which was 1.97MPa. XRD results show that the filling paste sample with 0.5% gypsum has more and stronger C-S-H diffraction peaks than the sample with 3% gypsum. SEM results showed that flocculent C-S-H gel and needle stick ettringite (AFt) appeared in the specimen of filling paste mixed with 0.5% and 3% gypsum. The internal structure of the filling paste specimen mixed with 0.5% gypsum is denser and less porous than that of the specimen mixed with 3% gypsum. The amount of gypsum can increase the peak strength of specimens because the C-S-H gel and AFt and other hydration products are intertwined to reduce the damage of the specimen quality. The reason for the low strength of the excessive gypsum specimen is that the expansive aft destroys the internal space structure of the specimen, resulting in microcracks.
- 1
Large Deformation Prediction Model and Supporting Measures of Soft Rock TunnelAbstract:
The weak surrounding rock has the characteristics of easy softening, poor integrity, low mechanical strength, etc., which makes it easy to induce different degrees of deformation and damage under excavation disturbance, which seriously affects the stability of the tunnel. Aiming at the large deformation of the soft rock tunnel''s vault, arch shoulder, arch waist and other parts, it is predicted based on gray theory, combined with bolt support, the support is designed at the maximum predicted value (Smax), and analyzing through numerical simulation control effect of different bolts, spacing (d), length (L) on the maximum displacement (νmax) and maximum stress (σmax) of surrounding rock. Researchs indicate that: the gray model has high prediction accuracy, the best prediction time is one week, and the maximum error is only 2.99%; with the decrease of d, resin bolt support has a significant supporting effect compared with mortar bolt support, with νmax and σmax reduced by 70.69% and 58.81% respectively; as L of the bolt increases, compared with the mortar bolt support, the resin bolt support has a more obvious restraining effect on the surrounding rock deformation, and νmax and σmax are reduced by 57.89% and 40.23% respectively;when 4.5m﹤L﹤6.0m, 0.6m﹤d﹤0.7m, resin bolt support should be adopted. in other areas, mortar bolt support or resin bolt support has less significant difference in controlling surrounding rock deformation.
- 1
Stepwise staggered upward slicing and filling methodAbstract:
Industry insiders at home and abroad define a refractory ore body as a gently dipping medium thick vein with an inclination Angle between 20° and 30° and a thickness ranging from 10m to 15m. The approach method can be used for safe mining. However, frequent roof connection during filling seriously affects the productivity. Although the efficiency of slicing and filling mining is high, the safety of personnel and equipment cannot be guaranteed. Through the research and development of stepwise staggered upward slicing and filling mining method, the two methods of slicing and filling are skillfully combined together, which can not only give full play to the advantages of large production capacity of slicing mining, but also ensure the safety of workers to a large extent. Field use shows that the method by layered HeJin Road two different mining methods staggered arrangement, on the one hand, adhere to the principle of safety mining, on the other hand to ensure that the mining capacity of single stope comprehensive production capacity of 113 t/d, poor loss control in the double within 8%, dilution rate 7.8%, the loss rate of 5.4%, experiences for other mines.
- 1
Influence of Water Content on Sand Consolidation Strength of Acrylate SlurryAbstract:
In order to explore the main factors affecting the sand consolidation strength of acrylate slurry and its influence mode, the orthogonal test was used first to analyze that the water content of sand had the greatest influence on the sand consolidation strength of acrylate slurry within the cementable range. On this basis, the relationship between water content of sand and compressive strength and tensile strength was obtained by nonlinear fitting. Finally, combined with the microscopic structure of the specimen, the influence of water content on the strength of the sample is proposed. The results show that: (1) The relationship between the water content of sand and the compressive and tensile strength of the sample is in accordance with the power function, and the index is negative; (2) The water in sand exists in the form of bound water and free water, and there are three ways to affect the strength of the sample: a. The combined water acts on the surface of sand in the form of water film, which reduces its friction shear strength; b. Part of the free water reacts with the slurry, which changes the physical and chemical properties of the cementation and reduces the strength of the main skeleton; c. The gas-liquid two-phase change of reaction residual free water occurs during the molding process of the sample, which makes the pore between cement and sand increase.
- 1
Comprehensive evaluation of stability shaft pillar based on AHP-3DECAbstract:
The main shaft of the Large scale rock gold mine is within the range of the mining rock movement boundary. The shaft pillars in the deep area are seriously under pressure. The impact of underground large-scale mining disturbances on the stability of the shaft security pillars lacks a systematic assessment and demonstration. In this paper, the comprehensive evaluation of the stability of shaft security pillars is carried out by means of monitoring of surface subsidence and deformation of mining area, analytic hierarchy process (AHP) safety evaluation, and numerical simulation of historical mining process. Mining area settlement monitoring shows that all surface settlement deformation values have not exceeded the limit, and are generally within the normal fluctuation range; the current safety assessment value of the analytic hierarchy process is between 0.590 and 0.740, and the safety evaluation level and results of most stopes are level II, the safety status of the security pillar is generally good; numerical simulation results show that the new and old main shafts and auxiliary shafts are affected by slight disturbances in the historical mining process, but the rock displacement is less than 1 to 2 mm, which is within the range allowed by the specification inside.
- 1
Risk Analysis on the Social Stability of a Project about Copper Mining and BeneficiationAbstract:
In order to control all risks of the proposed project are in a "Low-risk State and Controllable", it is necessary to implement social stability risk response measures. The paper was based on the basic framework of risk analysis and assessment generally implemented at home and abroad, combined with China's national standards for risk management, then followed the steps required by the specification: Investigate risks, Identify risks, Estimated risk, Determine measures to prevent and defuse risks, The expected risk level after implementing the measures, Draw conclusions of risk analysis, and conduct a risk analysis of social stability on a copper mining and beneficiation project. 9 main risk factors are identified: Policy planning approval procedures, Land acquisition and relocation, Inflammable and explosive hazard sources, Tailings pond, Ecosystem, Water-environment, Solid waste, Construction safety and environmental protection, Social Security. After taking a series of professional measures, the impact of all identified risk factors has been minimized and can be controlled. The paper provides reference and reference for the compilation of social stability risk analysis chapters for major investment projects in non-ferrous metals, provides a basis for investment decision-making, and provides direction for project risk management.
- 1
Research on detection of overburden fracture development in the first coalface based on the combination of dynamic and static dislocationAbstract:
In order to study the development state of overlying rock cracks in the first mining face before and after mining, taking 50105 working face of Faer coal mine as an example, the detection method of dynamic and static dislocation is proposed. Based on the theoretical analysis of overburden movement curve and empirical formula, the excavation simulation is simulated by UDEC software with discrete element method. Combined with network parallel electrical method and borehole camera method, the development process of overburden cracks and the final stable height are analyzed. The results show that: in front of the mining area, the advance stress fracture begins to develop, and the rapid displacement difference of the fracture appears in the overlying rock separation stage; the lithology above the coal seam is less, the hard rock layer is close to the coal, the main overburden layer is silty clay containing gravel, the stability of overburden rock is poor, and the measured height of fracture development is greater than the theoretical height; in the stable area of goaf, the overburden containing gravel silty clay is recompressed In fact, the top crack is closed and the measured height of the crack is reduced. The research results have a new understanding of the development of fractures in overlying strata with few lithology in the first mining face.
- 1
PCA-KD-KNN based model for discrimination of mine water inrush sourceAbstract:
In the process of coal mining, the occurrence of mine water inrush accident seriously threatens the safety of coal mine production and workers" lives. In order to quickly and accurately identify the source of mine water inrush and effectively prevent water disaster, this paper established a discriminant method of mine water inrush based on KD-dimension tree and K-nearest Neighbor algorithm. According to the difference of hydrochemical characteristics of different aquifers in mine, 9 kinds of hydrochemical components were selected as the discriminant index of water inrush source. Principal component analysis (PCA) was used for data dimension reduction; K-dimensional tree structure was further used to store training samples to improve the efficiency of data search, and then KNN algorithm was combined to distinguish water inrush source. Taking the YuZhou mining area as an example, 24 groups of measured data of 4 aquifers in the mining area were used to build the model, among which 16 groups were used as training samples and the other 8 groups were used as test samples. The discriminant results were compared with those of the traditional KNN algorithm. The results show that KD-Tree determines the three training samples closest to the samples to be tested, which reduces the computational complexity of KNN algorithm. By comparing the discriminant results between KDtree-KNN method and traditional KNN algorithm, the accuracy of the method used in this paper is increased by 25%, indicating that KDtree-KNN method can make the discriminant results more rapid and accurate.
- 1
NUMERICAL SIMULATION RESEARCH ON THE SAFETY OF FILLING MINING OF THE UNDERSEA OREBODYAbstract:
The mining of ore bodies under the sea is difficult, and its technical requirements and safety requirements are high. Any slight seawater leakage may cause major safety accidents such as the destruction of wells. This article takes the southwest wing section of Sanshan Island as the research object, uses FLAC3D to simulate and analyze the safety of the mining process of this section, and combines the field investigation to evaluate the safety of the southwest wing section. The simulation results show that the tensile stress in the west of the 131 line pillar increases gradually with the mining of the ore body, and a plastic zone about 15m deep appears on the top plate and upper and lower plates. The fault fracture zone is unstable and the safety is low. The tensile stress in the area west of the 131 line pillar is relatively small, and the roof of the pillar area produces a plastic zone of about 3m. The upper and lower disks are stable and safe. The roof of the area east of the pillar produces a plastic zone of about 6m, and the upper plate is relatively broken, the lower plate is stable, so the safety is average.
- 1
MICROSCOPIC CHANGES OF GRANITE UNDER THERMAL SHOCKAbstract:
In order to analyze the meso-fracture characteristics and porosity change laws of granite under thermal shock, this paper is based on the thermal shock test platform developed by the in-situ modified mining laboratory of Taiyuan University of Technology to conduct thermal shock tests on granites at different temperatures. This paper uses a high-precision micro-CT scanning system to scan the granite after thermal shock, and uses the CT image analysis system developed by the research group to perform three-dimensional reconstruction of the scanned layers after binarization, and finally obtain a digital model of the granite cube. By extracting images of pores and cracks from the model, and calculating the porosity of granite under different temperature thermal shock, the failure law of granite can be obtained. The research results demonstrate that the thermal shock of granite changes significantly with the increase of heating temperature. With the increase of heating temperature, cracks on the surface of granite gradually develop, and the porosity of granite increases. The temperature threshold for thermal shock damage of granite is 400℃. When the thermal shock temperature of granite specimen is 300℃, the pores inside the core increase, but the pores are not connected to form cracks. When the thermal shock temperature is 400°C, the pores in the core increase significantly and began to crack. When the thermal shock temperature is 500°C, the pores begin to penetrate to form cracks and develop rapidly. In addition, the study also found that due to the anisotropy of mineral particles under the action of thermal shock, uneven thermal cracking occurs in the thermal cracking process of granite, and the damage first occurs on the rock surface.
- 1
EXPLORATION AND VISUALIZATION ANALYSIS OF A GOAF WITH MEDIUM-DEPTH HOLE TEST IN A COPPER MINEAbstract:
Aiming at the increasing difficulty of controlling the stope boundary because of the structure size increases significantly and the stable state of the roof affected by blasting disturbance cannot be guaranteed under backfill, in this paper, the BLSS-PE cavity detection system was used to carry out many field scans of the test stope in the copper mine, three-dimensional models of the goaf at different stages were obtained, and they were combined with designed model, the coincidence relationship was analyzed between the designed boundary and the cavity boundary after blasting, the implementation effect of blasting was evaluated; The displacement changes of goaf roof and left and right sides were compared in different mining stages, the applicability of medium and deep hole stoping technology in this mine was verified, which lays a foundation for the popularization and application of medium and deep hole mining method in this mine in the later stage.
- 1
Discuss the importance of the information construction of tailing pond safety managementAbstract:
The high development of new generation information technology such as big data and artificial intelligence provides new ideas for the transformation of tailings pond safety management mode. The traditional safety management mode can be gradually developed to the direction of informatization, digitization and intelligence to improve the management level. Combined with the current rapid development of information technology, this paper focuses on the analysis of the practical significance of information construction in the safety management of tailings pond. Through the investigation of the current situation of tailings pond safety management, this paper points out the problems encountered in the process of information construction, and puts forward solutions to these problems, so as to provide reference for enterprises to realize the informatization construction of tailings pond safety management and to realize effective information management.
- 1
STUDY ON GAS CONTROL TECHNOLOGY OF WORKING FACE BY HIGH LEVEL DIRECTION HOLE DRAINAGEAbstract:
In order to reduce the risk of abnormal gas emission about the goaf, this paper proposes a technology based on high-level directional drilling to achieve gas drainage in the goaf and effective gas control in the goaf. Based on the research background of 232 Shimen drilling field in 23125 working face of Panjiang Coal Mine, the range of caving zone and fracture zone in goaf is determined by theoretical and numerical analysis, and the key parameters such as azimuth of high-level directional drilling are optimized. The total drilling footage is 2820m and the hole forming rate is 90%. Directional drilling is used to exhaust the gas in the goaf to evaluate the drainage effect. The results show that the high-level directional drilling technology can accurately locate the location of the caving zone and the fracture zone, and can effectively achieve the directional gas extraction in the goaf. Through the analysis of the gas concentration in the drainage hole, it is found that the maximum gas concentration in the single hole is 63%, with an average of 40% - 55%. After a certain period of drainage, the gas in the goaf is significantly reduced by about 17%. This technology realizes the purpose of gas control in goaf, and can provide some reference for efficient gas control in goaf.
- 1
Risk assessment of coal and gas outburst basedon entropy weight mutation theoryAbstract:
For coal and gas outburst is uncertainty and nonlinear complex system, in order to fine out the forecast work, put forward the entropy weight method and combined catastrophe theory of coal and gas outburst risk assessment methods. Taking Guizhou Gaoshan Coal Mine 7# coal seam as the research object, according to highlight the study of mechanism of coal and gas outburst risk evaluation system is established, analyzing the relative importance of hazard factors from geological and non-geological factors, and verifying its rationality through engineering examples . The results show, On the basis of the measured data of the mine, using this evaluation method, it is obtained that the total abrupt transition membership degree of No.7 coal seam is 0.852 and the risk state is relatively strong. The type of media damage, coal firmness coefficient, structural complexity, coal seam effective porosity and maximum initial gas release velocity are the main reasons for low safety. Mutation model calculation of total membership value with mine actual situation and the appraisal report have good consistency, can be a very good for safety evaluation of coal and gas outburst provide theoretical guidance.
- 1
Incremental Automatic Ore Sorting System ResearchAbstract:
The separation of mineral resources is of great significance to the ore production industry. Artificial coal gangue separation exists in coal gangue, for example, low efficiency, big workload, the problem such as poor working conditions, and the coal gangue sorting system based on traditional machine learning accuracy is low, and the existing coal gangue knowledge prior model cannot effectively cover new ore, to extend the data set to training model, long training time and training efficiency is low. To solve the above problems, an incremental automatic coal gangue sorting pipeline is proposed. Based on the actual engineering needs, a deep convolutional neural network was constructed to realize the efficient sorting of gangue images, and the deep incremental learning algorithm was used to realize the incremental learning of the automatic gangue sorting pipeline. The results show that the classification accuracy of incremental automatic sorting system of coal gangue can reach 99%, higher than that of traditional machine learning algorithm, and has the ability of incremental learning.
- 1
Optimization of Stope Structure Parameters Based on Game Theory-Improved TOPSIS ModelAbstract:
When mining steep and thin ore bodies, the complex and diverse indicators in the evaluation model for determining reasonable stope structure parameter schemes lead to the problem of low prediction accuracy. This paper proposes a combination of weighting based on analytic hierarchy process and entropy method, and introduces two-party weights optimized by game theory to construct game theory-improved TOPSIS comprehensive evaluation model. Eight evaluation indicators are selected from the three aspects of safety, economy and technology to analyze and evaluate the optimization plan, determine the optimal stope structure parameter plan, and use FLAC3D software to perform numerical simulation on each plan, and verify each other with the evaluation model. Research shows that the evaluation model can more scientifically and effectively select reasonable structural parameters in the optimization of complex stope structure parameters, and provide guidance for similar mine stope structure parameter optimization.
- 1
Experimental Research on Beneficiation of a Lead-Zinc Mine in YunnanAbstract:
The lead grade of a lead-zinc mine in Yunnan is 1.09% and the zinc grade is 6.02%. Among them, zinc mainly exists in the form of sulfide ore, and lead mainly exists in the form of oxidized ore. In order to develop the ore reasonably, the useful elements in the ore are efficiently recovered and beneficiation test research is conducted. After the raw ore is ground, the flotation test process of one coarse, three fines and three sweeps is adopted and the test process of tailings re-election and discarding the tailings and then flotation of lead is used to obtain qualified lead and zinc concentrates.The lead concentrate grade reached 31.85% and the recovery rate was 40.18. %; the zinc concentrate grade reaches 51.89%, and the recovery rate is 84.95%.
- 1
Study on gas flow behavior in a fractured coal sampleAbstract:
Deep coal mining usually encounters complex geological structure, high in-situ stress, and high pore pressure, which leads to a high risk of gas outburst and water inrush. The abrupt increase of coal permeability due to the fracture evolution in mining is a key factor causing the above disasters. In this study, CT scanning was first used to image the fracture morphology in a coal sample after uniaxial compression test. Then three-dimensional digital model of the fracture was extracted and established using the Hessian matrix image processing. Moreover, the lattice Boltzmann method (LBM) was employed to calculate the gas flow behavior. The results showed that the coal permeability increased by nearly four orders of magnitude due to the formation of the fracture. This study provides an effective method for quantitative analysis of gas flow behavior in coal after the mining-induced disturbance, and provides theoretical basis for safe coal mining.
- 1
Comparative experimental study on thermal conductivity and characteristics of granite before and after thermal shockAbstract:
Thermal shock rupture has a great influence on the thermophysical properties of granite. In order to study the effect of thermal shock on the thermal conductivity and thermal characteristics of granite, the temperature field and temperature gradient field of granite before and after thermal shock treatment under conduction heating were tested and the results showed that: (1) Impact thermal stress destroys the binding state of granite mineral particles, causing the granite solid skeleton to rupture and form a large number of thermal shock cracks, which eventually leads to the deterioration of granite's thermal conductivity and abnormal heat transfer characteristics; (2) The cracks generated by thermal shock cracking have a great influence on the distribution of temperature and temperature gradient, and the distribution of temperature and temperature gradient is highly correlated with the location of the crack.; (3) The heating process of granite under conduction heating can be divided into three stages: rapid heating stage, slow heating stage, and stable stage according to the heating rate; (4) After the thermal shock, the time for the temperature gradient of the granite to reach the peak value and stable value during the conduction heating is delayed. This study has promoted the further development of the theory of rock thermal failure.
- 1
Experimental study of dynamic mechanical characteristics of thick-walled cylindrical granite under dynamic and static coupled cyclic impactAbstract:
In order to study the dynamic mechanical characteristics of thick-walled cylindrical granite under the action of dynamic and static coupled cyclic impact, an improved Hopkinson bar was used to select different axial prestresses to perform constant amplitude cyclic impact on granite samples. The test results show that the reflected wave and transmitted wave of the specimen appear at the maximum and minimum peaks during impact failure; different axial prestresses have different effects on the dynamic deformation modulus and maximum strain of the specimen; with the increase of axial prestress Large, the combined strength of the specimen shows an increasing trend, showing a certain "strengthening effect". In the process of cyclic impact, the dynamic strength and strain rate of the specimen are opposite, showing a good strain rate effect; the axial prestress affects the failure form of the specimen. With the increase of the prestress, the specimen undergoes shear- The tensile failure transitions to a failure mode dominated by shear.
- 1
Optimization and numerical analysis of supporting parameters of graded surrounding rock roadwayAbstract:
In the process of mining, ground pressure easy to cause a deformation and failure of the roadway, reasonable and effective supporting of roadway can significantly reduce the influence of pressure on production activities, supporting intensity is too large, will greatly increase the production cost and production cycle, the support strength is too small, hard to ensure safety, to seek a reasonable support measures is an important part of the mine production. Taking a gold mine in Shandong Gold as the background, based on the roadway support theory, relying on the existing mine support methods, Flac3D numerical software was used to conduct in-depth analysis on the displacement and plastic zone deformation of 1780m horizontal roadway under different support parameters. Meanwhile, the grey correlation analysis method was used to optimize the support parameters. According to Ⅲ level of surrounding rock, the research results show that the C30 shotcrete thickness is 70 mm, the pipe joint bolt diameter of 40 mm, length is 1.8 m, anchor net degree 2 m×2 m for the optimal supporting design; For Ⅴ level of surrounding rock, shotcrete、steel stents anchor supporting, steel support spacing of 1.5 m, to achieve the effective control of roadway deformation. At present, the research results have entered the engineering application stage and achieved a relatively ideal effect.
- 1
Study on the influence of Geomat on the stability analysis of tailing damAbstract:
Geomat is a kind of geosynthetic material commonly used in tailing dam. It has superior drainage performance and strong horizontal reinforcement effect, which can improve the stability of tailing dam. Combined with a high tailing dam project, the seepage control effect of the geomat of the tailing dam is analyzed by the saturated seepage finite element method, and the stability of the dam slope and the increasing stability mechanism of the geomat are analyzed by the strength reduction method. Under normal operation conditions, when the geomat of tailings dam works normally according to the design, its drainage effect is significant, which can effectively reduce the saturation line of dam body (27.42m at most), improve the stability of dam slope, and increase the safety factor by 28.0%; when it is completely silted up, the seepage control of dam body does not meet the requirements, but its reinforcement can still increase the safety factor by 7.7%. The geomat buried deep in the dam body can play a role of reinforcement, which makes the sliding of the dam slope change from the deep arc sliding to the surface sliding of the dam slope, that is, the geomat passes through the original most dangerous sliding surface of the dam slope, and its reinforcement improves the stability of the dam slope. In the design, the influence of the drainage and reinforcement of the geomat on the stability of the tailings dam slope can be considered comprehensively, and the reinforcement can be used as the safety reserve for the safety evaluation of the stability of the tailings dam slope.
- 1
Preliminary Research and Discussion on the Superiority of 8 - shaped Anti-slide PileAbstract:
This article through the analysis of all kinds of commonly used in the slope engineerings of pile type and matching construction method and its existing problems, and puts forward a new type of slope retaining structure - figure 8 anti-slide pile, and from under the ideal state of plain concrete under the condition of theoretical analysis and numerical simulation analysis of the preliminary verification on the anti-slide pile structure has excellent bending performance, preliminary validation on the anti-slide pile structure has good economy and safety, and high degree of mechanization, short time limit, big to resist lateral force, and many other advantages, can be in the future instead of rectangular artificial dig-hole pile, has a broad application prospect.
- 1
Study on overburden breaking and stress variation law of fully mechanized mining face under the condition of composite roofAbstract:
Aiming at the technical problems of composite roof stability control in 9108 working face of Changshun coal mine of Shanxi Jinneng group, the mechanical model of overburden fracture analysis of composite roof working face is established by using the research methods of theoretical analysis, physical simulation and field meas-urement, and the roof breaking law and ground pressure behavior law of fully mechanized working face under the condition of composite roof are analyzed theoretically. The theoretical analysis results show that the limit caving step distance of composite roof in 9108 working face is 35.21m, and the periodic weighting step distance of composite roof is 14.37m. The similar simulation results show that: the average periodic weighting step distance of 9108 working face composite roof is 18.4 m, and the first caving step distance of composite roof is 31.5 m; the main failure process of composite roof is tensile failure. The results of numerical simulation show that the main deformation and failure step of 9108 working face is 30 ~ 40m. The field measurement results show that the first caving step distance of composite roof in 9108 working face is 32m, and the periodic weighting step distance is 17m. The field measured results are consistent with the results of theoretical analysis, similar simu-lation and numerical simulation, which verifies the rationality of the theoretical analysis, similar simulation and numerical simulation results, and reveals the overburden breaking law of fully mechanized working face under the condition of compound roof in 9108 working face. The research results of this paper provide technical reference for safe and efficient mining of 9108 working face in Changshun coal mine.
- 1
Particle flow numerical simulation of triaxial compression in a metal mine tailingsAbstract:
Abstract: In order to explore the meso-mechanical properties of tailings from a tailings pond in Hunan Province, the numerical models of consolidated undrained triaxial test were established by using the particle flow numerical simulation software (PFC3D).The simulation results were compared with the results of laboratory geotechnical tests, and the high coincidence degree of stress-strain curves, peak strength and initial elastic modulus of the numerical simulation triaxial test and the laboratory triaxial test was taken as the criterion to determine the numerical simulation mesoscopic parameters of particle flow. After a large number of numerical tests using PFC3D software, it was found that the numerical simulation of tailings samples under different confining pressures was basically consistent with the stress-strain curves of laboratory tests. Compared with the high confining pressure, the simulated test results under the lower confining pressure are more consistent with the laboratory test results. Both large initial porosity and high confining pressure can inhibit the dilatancy of triaxial samples. The initial coordination number of the numerical model is large, which indicates that the contact degree of particles in the model is good to some extent.
- 1
Research and Application of Minor-Diameter Equal-Wall-Thickness Positive Displacement MotorAbstract:
Aiming at the problems of low power in rotary cutting and low efficiency in sliding directional drilling in rock formation of 73mm directional BHA underground coal mine, the research and application of minor-diameter equal-wall-thickness positive displacement motors are carried out. Comprehensive analysis of the technical development of equal wall thickness positive displacement motor and the characteristics of near-horizontal directional drilling conditions in coal mines, a 73mm equal-wall-thickness positive displacement motor was developed, performance comparison tests were carried out, and actual drilling was carried out in directional holes in the rock formation of coal mines. The results show that the rated torque of a minor-diameter equal-wall-thickness positive displacement motor can be increased by about 1 times compared to conventional positive displacement motors of the same specifications. Under the same formation conditions, the mechanical efficiency of sliding directional drilling can be increased by more than 30%. The minor-diameter equal-wall-thickness positive displacement motor provides a new method for improving the efficiency of sliding directional drilling in rock formation holes in coal mines, and it is of great significance to expand the applicable range of 73mm directional BHA.
- 1
Study on flotation conditions of non-caking coal flotation based on surface modification with Span 80Abstract:
In order to reduce the amount of flotation collector for non-caking coal slime, a variety of methods have been adopted, including infrared spectrum analysis, small screening, small float and sink, etc. And the infrared spectrum, particle size composition and density composition are obtained. Besides, multi factor experiment and orthogonal test were carried out to obtain the best flotation conditions and the order of each factor. The results show that span 80 is suitable for surface modification of non-caking coal; the optimal flotation conditions are collector dosage 13kg/t, span 80 dosage 5kg/t, foaming agent dosage 195g/t, pulp concentration 60g/L; the order of the factors was collector dosage > tray dosage > foaming agent dosage > pulp concentration.
- 1
EFFECT OF FRICTION ON THE CHARACTERISTICS OF ORE-ROCK MIGRATION VELOCITY DISTRIBUTION IN ORE-STORAGE SECTIONAbstract:
In order to study the influence of the friction of the orepass wall on the migration velocity of the ore-rock in ore-storage section, the influence of friction on velocity distribution is analyzed via Beverloo empirical formula, stable mass flow theorem and Newton"s internal friction law. The influence characteristics of velocity distribution of ore-rock are explored by using discrete element program. It is found that the friction of the orepass wall is the main reason that the velocity difference of the migration exists under the same plane in ore-storage section, especially for the ore-rock deceleration near the orepass wall. The results show that:(1)when there is no friction in the ore- storage section of the orepass wall, the ore-rock moves in a vertical and uniform motion; (2) when there is friction, the velocity of ore-rock in contact with the orepass wall decreases, which leads to the difference of velocity between adjacent ore-rock under the same plane, and the internal friction between ore-rock particles, which affects the velocity distribution characteristics of ore-rock in the whole ore-storage section; (3) the migration velocity of ore-rock is more different in the funnel of ore-drawing well under the greater friction; (4) the friction coefficient between the orepass wall and the ore-rock increases, and the influence range and degree of friction increase; (5) the measures and suggestions to solve the problems of orepass blockage and wall wear by controlling the friction of shaft lining are put forward.
- 1
Analysis on the Policy Risk of a Tungsten Mine Reconstruction based on AHP and Risk Matrix ModeAbstract:
The risk of investment project comes from the uncertainty of a series of economic factors , the change of internal and external environment of project implementation. In order to avoid risks, it is necessary to analyze risks in the process of investment management. In this paper, the risk matrix method and AHP are combined to construct the evaluation system from the severity dimension of risk consequences, so as to obtain the risk possibility value. Then, taking the reconstruction and expansion of a mine as an example, the paper analyzes the policy risks and concludes that the risk level of environmental protection policy is very high, and the risk level of land acquisition is high. Through the analysis of the investment changes of the project, it is found that the investment increase caused by the environmental protection policy is the most, followed by the investment increase caused by the land acquisition policy. Through the analysis of the risk matrix and the change of the investment amount, it is found that the higher the risk level, the greater the impact on the investment amount. This will provide reference for the future project investment, such as scientific and reasonable control of investment, strict implementation of risk management and monitoring of the project, and effective avoidance of major risks of project investment.
- 1
Study on width Optimization of stope with two-step staggered upward horizontal slicing and filling methodAbstract:
In view of the large Yin Gezhuang shandong zhaoyuan gold mine adopted some pillar up to the level of layered filling method generally cause big loss rate of ores, and after entering deep mining in mines, where pressure increases gradually, causing some room stoping process in large part pillar caving and fracture damage, resource recovery difficult, job security risk is high, and as a result of the existence of upper plate fracture zone, once problems cause slide easily affected by stress. Considering large Yin Gezhuang gold mining technical condition, on the premise of guarantee safe production in mines, as far as possible to reduce ore loss in the process of mining, the maximum improve resource utilization, in combination with site selection panel on the staggered type to horizontal layered filling method, in order to ensure the stability of stope mining process, adopt the method of adopting the method of numerical simulation of the stope width of parameter optimization research, 9 are calculated and analyzed under the condition of stope surrounding rock stress and displacement of roof convergence and the plastic zone distribution results after excavation, ultimately determine the step width of stope 7 to 8 m, second step width of stope 6-7 m, In the production process, the high value is better and the low value is worse. It can be used for reference by similar mines.
- 1
Study and Optimization of Rheological Properties of High Concentration Tailings Slurry with Different Gradation in a MineAbstract:
The fluidity of filling slurry is the basis of realizing high concentration cemented tailings filling, and tailings gradation is one of the important factors affecting the rheological properties of slurry. In order to explore the relationship and mechanism between tailings gradation and slurry rheological properties, tailings with different gradations were prepared manually, and rheological properties tests were carried out. The influence mechanism of gradation on rheological properties of slurry was explained and optimized from the visual and microscopic perspectives. The results show that: the rheological properties of tailings slurry with different proportions in the mine conform to Bingham model, and there is an exponential growth relationship between the fine sand content and the yield stress and plastic viscosity of the slurry, and the optimal ratio is -74μm, accounting for 40%. According to the test results, the technical transformation is carried out to optimize the tailings gradation in actual production and realize safe and efficient mining.
- 1
Influence of the Reverse Speed of Tray on Grinding Ball Motion in Omnidirectional Planetary Mill based on the Discrete Element MethodAbstract:
The omnidirectional planetary mill simulation model is established by discrete element software (EDEM). The operation process of the ball mill was simulated, and the particle collision status at various reverse speed was obtained. In addition, the average maximum collision force and the collision energy loss at different tray reverse speed were analyzed. The results showed the motion of the grinding ball will change periodically with the turning of the tray and the grinding effect between grinding balls is greater than that of impact crushing. The optimal reverse speed of tary is 2 rpm.
- 1
Study on Performance Tests ofSSelective Grinding in Vanadium-Titanium Magnetite Ore in PanzhihuaAbstract:
The capability of grinding and separating of titanomagnetite and ilmenite in Vanadium-Titanium magnetite ore in Panzhihua is different. And the phenomenon of selective grinding in Vanadium-Titanium magnetite ore is happen. This experiment studys on performance of selective grinding during first stage separation in raw ore in the laboratory, and reveals that the capability of grinding and separating of titanomagnetite and ilmenite in Vanadium-Titanium magnetite ore is different. This study optimizes the parameter of grinding during first stage separation. Study finds that -0.074mm levels of feed size during first stage separation decrease by a percentage of 5.94 compared to the production site. But productivity, grade and rate of recovery increase by a percentage of 1.01,1.04,2.79 separately. The test improves the index of Iron concentration.The size of tailings of separation Fe which is raw material for titanium separation decreases relatively. And -0.038mm levels of tailings have been greatly improved and decrease by a percentage of 5.49.
- 1
Research on Coal Mine Intelligent Evaluation Based on Subjective and Objective Weighting VIKOR MethodAbstract:
As my country's coal mine intelligence standard construction is still in its infancy, and coal mine intelligence related standards and norms have not yet been perfected, building a coal mine intelligence evaluation index system has become the focus of intelligent construction research. In order to overcome the shortcomings of the single weighting method, an intelligent coal mine evaluation index system was established from nine aspects including transportation, industrial video monitoring, and gas drainage subsystems. The improved G1 method and the CRITIC method were used to determine the subjective and objective weights of each indicator. The subjective and objective weights are integrated to obtain the combined weights. The VIKOR evaluation model is introduced to comprehensively consider the group benefit value and individual regret value to make the evaluation result more accurate, and use this model to comprehensively evaluate the degree of coal mine intelligence. The results show that the VIKOR evaluation model can simultaneously consider the group benefit value and the individual regret value, making the final evaluation value more accurate; the evaluation result of the comprehensive evaluation model is consistent with the actual degree of intelligence of the coal mine, which verifies the feasibility of the evaluation model .
- 1
YANGSNing1,3SYINSXiangang1,2 OU Renze1,3 LIN Weixing1,3#$NL(1.ChangshaSInstituteSofSMineSResearchSCo.Ltd,Changsha,HunanS410012,China;Abstract:
For Angle in between 20 ° to 30 °, thickness between 4 m to 15 m flat dipping medium thick vein of unstable, by gravity ore difficulty encountered in the process of mining and roof control means of complex lead to the safety of the poor, in the face of such a difficult situation, even around the world in the industry to define it difficult mining. Through the research and development of middle and deep hole rhomboid ore house subsection filling mining method, operators do not need to enter the exposed roof work, to a large extent to ensure the safety of workers, select efficient middle and deep hole drilling and blasting ore, improve the production efficiency. The results of field use show that the method can be used for quick extraction and quick discharge through medium and deep holes, which, on the one hand, complies with the principle of safe mining, and on the other hand ensures that the mine can complete the annual production task, with the production capacity reaching 400t/d, Dilution rate 11.3%, and loss rate 13.5%, which can be used for reference by other mines.
- 1
Study on Overburden Failure Rule of Cose Coal Seam Group under Repeated MiningAbstract:
Taking YangMei close distance coal seam group of an as research object, through two-dimensional physical methods of similar material simulation experiment, for close distance coal seam group of cases repeating mining strata damage and crack law of development were analyzed, and the results show that the stratum of 12 # coal seam from an average of 18 cm and 15 # coal seam in periodic weighting interval in an average of 14.5 cm, the downward mining conditions, coal seam mining under periodic weighting interval less than on coal seam mining periodic weighting interval. The height of the simulated mining caving zone in no.12 coal seam is 8cm, and the maximum height of the simulated mining caving zone in No.15 coal seam is 17cm, and the maximum height of the simulated mining caving zone is 116cm. The relevant conclusions can provide reference for the study of overburden failure of coal seam under similar conditions.
- 1
Research on the application of underground concealed goaf detectionAbstract:
In view of the difficult problem of detecting hidden Goaf in the process of underground mine changing to open-pit mining, taking the hidden Goaf in the lower part of open-pit of Yuanjiacun iron mine as the research object, this paper analyzes the technical characteristics and application of various detection methods of Goaf. Through a large number of field experiments, a set of geophysics detection, drilling exploration, 3d laser scanning and sonar detection, and other technical means of combination of detection methods, the accurate detection of Hidden Goaf in Yuanjiacun iron mine has been realized, and the high-precision solid model of Goaf has been successfully constructed. The successful application of this detection technology provides a reliable basis for the treatment of the lower open-pit Goaf, and has a strong reference to the detection of similar hidden Goaf.
- 1
Study on flow state of Y-shaped pipes in deep-sea miningAbstract:
In view of the complex flow field of Y-tube and the risk of ore leakage in deep-sea mining transportation test, the continuous phase flow field and particle field in Y-tube under different transportation conditions are analyzed. CFD-DEM method was used to simulate clean water condition and two-phase flow condition, and the pressure distribution, single particle motion characteristics and particle swarm motion characteristics in Y-tube were obtained. The results show that the pressure distribution in the Y-tube is influenced by the curvature of the bend and the flow distribution at the inlet of the Y-tube. The single particle flows on the wall surface of the curved pipe. After being subjected to the effect of upwelling, the particles migrate upward. When the upwelling is low, the particles will collide with the bottom wall of the pipe. When the upwelling velocity is not enough, the particles will be lost through the bottom pipe. As a result of particle flow, the strength and scale of the low pressure vortex area in the Y-tube are weakened.
- 1
Study on the Fire Smoke Flow Characteristics in Deep Well "T" RoadwayAbstract:
In order to study the law of smoke flow when a fire occurs in a deep well "T" roadway, the fire dynamics software FDS is used to numerically simulate fires with different ambient temperatures, different fire source powers and different wind speeds in a high humidity environment. Changes in temperature, toxic and harmful gases and visibility in T" type tunnel II. The research results show that with the increase of the ambient temperature, the temperature in the tunnel becomes higher and higher after the fire, and the concentration of CO and CO2 is also increasing; The temperature, CO and CO2 concentration in the roadway increase, and the visibility decreases; after a fire, when people are in the downwind direction of the roadway II, it is not advisable to increase the wind speed excessively for rescue, because excessively increasing the wind speed will cause more smoke to enter In the downwind roadway, it causes greater harm to personnel.
- 1
The Sustainable Eevelopment Inspirationfrom the Resource-based Cities’ Transformation in Eastern ChinaAbstract:
Resource-based city is the pillar of regional economy, its life cycle is usually accompanied by the exhausted of resources, bringing environmental damage, industrial imbalance, unemployment and other problems. Under the influence of the western development and the construction of the Silk Road Economic Belt, Xinjiang"s economy has entered an unprecedented period of development opportunities. Resource mining enterprises are booming. After abundant investigation, taking Fuxin, Liaoning, Tangshan, Hebei and Jiaozuo, Henan as examples, this paper makes an in-depth analysis of the experience and lessons in the transformation process of mining cities, and combining the characteristics and current situation of mining cities in Xinjiang forwards the following suggestions: First, to posit accurately, plan overall and outstand industrial advantages. Second, relying on the core industry, to develop in an all-round way and extend the industrial chain. Third, showing regional advantages, to lead regional economic development and tap the potential of urban service industry. Fourth, base on the construction of green mine, to adopt new technology and develop new industry. Fifth, besides large state-owned enterprises, to support new economic formsand to promote the sustainable development of mining cities in Xinjiang.
- 1
Measurement Methods of Flow Field in FlotationAbstract:
With the continuous development of modern fluid mechanics measurement technology, a variety of advanced measurement methods have been gradually applied to the accurate measurement and display of multiphase fluid velocity, gas holdup, bubble size and other parameters in flotation equipment, mainly using particle images Velocity measurement (PIV) technology and high-speed dynamic camera technology measure particle and bubble velocity fields; use conductivity probes and electrical resistance tomography (ERT) technology to measure air holdup and bubble size parameters. In response to these measurement methods, combined with some typical cases accumulated by the author’s research team and other researchers in the long-term flotation measurement practice, the measurement principles, application status and limitations of these methods are introduced and summarized, and put forward in the subsequent research It is one of the future development directions to improve the spatial and temporal resolution of these detection methods and strengthen their applicability in complex flow environments.
- 1
Research on Separate Type Heat Pipe Recovery Technology of Mine Return Air Waste HeatAbstract:
Aiming at the practical problems of heat pipe heat exchange technology in the engineering practice of mine return air low-temperature waste heat recovery, a system scheme using separate heat pipe technology to extract mine return air waste heat is proposed. Taking a coal mine in Shanxi Province as an example, based on the technical and economic feasibility of the system scheme, based on the design principle of separated heat pipe heat exchanger, the overall design and description of the long-distance separated heat pipe heat exchange system for mine return air waste heat recovery are carried out, and the engineering actual effect is briefly evaluated. It is of great significance to broaden the applicable scope of separated heat pipe, to make full use of energy and to protect the environment.
- 1
Effects of rock fracture on rock breaking by cutting pick of roadheaderAbstract:
In order to optimize the design of the cutting head of roadheader and further improve the rock breaking efficiency and roadway driving speed, the influence and law of different crack positions on rock cutting by pick are studied.The numerical simulation model of rock with fracture is established and the finite element analysis is carried out.The stress distribution and cutting force variation law of rock cutting with fixed cutting speed are researched.The results show that: compared with homogeneous rock, the cutting force of cutting fractured rock is smaller; With the increase of the distance between the fracture area and the pick, the cutting force increases gradually, and the mean peak force of the cutting also increases. The specific energy of cutting at different crack positions is calculated, and it is found that when the distance between the fracture and the pick is 1 mm, the specific energy consumption of cutting is the lowest, which is reduced by 44.14% compared with homogeneous rock.
- 1
Study on the influence of coal seam dip angle on the stability of gob-side entry retaining support in fully mechanized top-coal caving faceAbstract:
In view of the problem that the hard support is often squeezed and sliding when the falling gangue in the gob of the gob is rolling down along the gob with a large angle of inclination, the stress distribution and displacement law of the working face with a large angle of inclination are analyzed by numerical simulation, and the support system with a combination of rigid and flexible is more suitable for the gob with a large angle of inclination, and the experimental tunnel is monitored in combination with the engineering practice. The results show that the stress in the upper part of the working face with large inclination is distributed in an arch shape, and with the increase of the coal seam angle, the vault moves to the upper end, and the stress release area in the upper part of the working face is large, which indicates that the stress in the upper end can be released in time, the vertical displacement of the working face roof has asymmetric zoning, and the vertical displacement of the middle and upper parts is much larger than that of the lower part displacement: adopt the method of natural filling of falling gangue to support the retained roadway. The final effect of retained roadway is significant. The displacement of the upper part of the roof is the largest, 278mm. The steel mesh is finally in the shape of "C", and the deformation of the middle part is the largest, 343mm. The stress of the upper side anchor cable of the roadway is greater than that of the lower side anchor cable, and the maximum value is 24mp. The monitoring data are within the controllable range, meeting the needs of the actual project.
- 1
Study on particle segmentationof blast furnace slag centrifugal granulation imageAbstract:
In the process of centrifugal granulation of blast furnace slag, particle segmentation based on image recognition is a key factor for real-time particle size detection. Aiming at the difficulty of testing the granule slag image particle bonding problem, after denoising the image, combined with the improved watershed algorithm for particle segmentation, the accurate segmentation of the bonded particles is realized. Aiming at the defect of watershed algorithm, combined with the fast algorithm of integral image, the local image of the particle image is binarized, and the morphological details are used to make up the details. The morphological reconstruction distance image algorithm is used to improve the watershed algorithm to segment the particle image. The processing efficiency is improved, the over-segmentation phenomenon is suppressed, and the bonded particle image is accurately segmented. The algorithm lays a foundation for accurately and quickly extracting the characteristic parameters of each particle.
- 1
Emerging Problems of Investment in African Mining Industry from Chinese Enterprises and CountermeasuresResearch under the COVID-19 EpidemicAbstract:
In recent years,Chinese investment entities have become increasingly active in the mining industry in Africa. According to incomplete statistics, by 2018, the number ofChinese enterprises going global is 252. Among them, China state-owned accounted for about 33%, private enterprises about 51%, and geological exploration institutes about 16%.Under the impact of the COVID-19 epidemic, the challenges faced by the three major investors in the view of the author are as follows. First, the African mining industry will be severely shocked by the epidemic. Second, Chinese enterprises in Africa may face abad business expectation in two years. Third, in some African countries, uncertain continuity and stability of mining policies can bring new policy and regulation risks. Forth, mining investment and business activities in Africa may fall into a trough in the short term, which poses difficulty for Chinese enterprises to gain risk investment and fund-rising. Five, the public opinion war and "responsibility-dumping" of the epidemic launched by Western countries against China will bring new pressures and challenges to enterprises. The author puts forward some countermeasures and suggestions. First, develop a counter-cyclical resource allocation plan by seizing opportunities accurately in the late stage of the epidemic. Second, investors could improve the cash flow situation of enterprises, and prepare for dealing with the possible unfavorable market situation. Third,enterprises with mature investment may carry out some construction and development plans and mine infrastructure project. Fourth, in the later stage of the epidemic, investment in Africa mining industry should be comprehensively considered and rationally adjusted.Fifth, investors should establish a win-win cooperation and sustainable development concept by placing more importance on technological innovation.
- 1
BUFFER PERFORMANCE OF STOCK SECTION OF ORE-PASS ON DISCRETE ELEMENT SIMULATION STUDYAbstract:
Reasonable utilization of the buffer performance of the stock in ore-pass storage section can effectively protect the bottom structure and shaft wall of the ore-pass, and alleviate the shock caused by ore discharge on the bottom structure to the greatest extent. To explore the buffer performance of stock to unloading in the ore-pass, the discrete element method is used to analyze the buffer process of the ore-pass under the impact of unloading in the ore-pass. The influence of the stock height on the buffer effect of the ore-pass, the stress characteristics of the side wall of the ore-pass are explored. Then determine the critical storage height under the current structure of the ore-pass and the particle size distribution of ore and rock is determined through the buffer ratio. The studies shows that: (1) under the impact of ore unloading, the ore and rock in the upper part of the stock collide violently, which disperses and attenuates most of the impact force; and the impact force at the lower part of the stock is mainly transmitted along the initial force chain network, and the arrangement of ore and rock remains unchanged, and part of the impact force is offset by friction resistance; (2) under the conditions of specified particle size distribution and diameter of storage section (6m), the critical height of stock is 7 m. On the whole, the stock buffer effect becomes better with the increase of stock height. When the stock height is less than 7 m, the stock buffer effect is obviously affected by the change of stock height; when the height is more than 7 m, the buffer effect is less influenced by the change of stock height; (3) the peak value of wall impact force decreases with the increase of stock height and D value (the distance between the side wall and the stock surface). In a critical stock height range from the stock surface, the wall impact force decreases rapidly, but outside this range, it decreases slowly;(4) combined with the research results, the specific measures for reasonable utilization of buffer performance of stock are proposed in three aspects of reasonable storage height, ore unloading and drawing management, which, to some extent, has guiding significance for mine production practice.
- 1
Research on rheological properties of tailings filling slurry with different particle sizesAbstract:
The rheological properties of filler slurry are an important factor affecting slurry pipeline transportation. Aiming at the tailings aggregate of an iron mine in Fujian, a study was carried out on the influence of the cement-aggregate ratio and the weight ratios of coarse and fine tailings to the rheological properties of the mixed aggregate filler slurry. First, using the laser particle size analyzer + sieving method, the mine"s coarse and fine tailings are analyzed for particle size to obtain the particle size distribution and particle size characteristic values of the mixed tailings. Secondly, a rheometer was used to measure the rheological parameters of filler slurry with different cement-aggregate ratios and different thickness ratios. Finally, based on the partial correlation analysis and quadratic polynomial regression analysis method, the correlation analysis of the rheological parameters of the slurry and the regression model were established. The research results show that the mixed tailings filler slurry conforms to the Bingham plastic body; as a whole, when the mass concentration and cement-aggregate ratio are the same, the larger the thickness ratio, the more the yield stress and viscosity coefficient of the slurry decrease; The cement-aggregate ratio has a great influence on the yield stress and plastic viscosity, showing a non-linear change law; the order of the correlation between the various factors on the rheological parameters of the slurry is: thickness ratio> cement-aggregate ratio; the model established by regression analysis and the model provide reference for pipeline resistance prediction.
- 1
Research on Different Mixer Blades for Preparation of Filling SlurryAbstract:
In the full tailings filling process, the quality of the prepared filling slurry has an important influence on the overall filling process. This paper studies the mixing effect of different blade shapes on the slurry, and numerically simulates and analyzes three common agitator blades, propeller type, six-blade open open type, and six-blade rushton turbine type. The simulation is based on the Euler model, the turbulence model uses the RNG k-ε mixing model equation, and the Syamal-O’Brien drag force model is used to obtain the simulation data of different blades. The fluid movement velocity distribution in the axial and radial directions of the slurry under the stirring action of different blades is compared, and the homogeneity is used as the criterion to determine the optimal speed of the mixer.
- 1
Study on Evaluation of Mixing Quality of Mine Filling Tailings SlurryAbstract:
With the emphasis on environmental protection by enterprises and the tightening of national tailings pond management policies, most mines use tailings slurry for goaf filling. The mixing quality of tailings slurry is very important for mine filling and mining. This paper selects commonly used tailings slurry quality evaluation indicators, and investigates multiple tailings filling stations under Shandong Gold. And the AHP method is used to propose a tailings slurry mixing quality evaluation system. It is hoped that the mixing quality of the tailings slurry can be evaluated to optimize the mixing quality, saving mixing operation cost.
- 1
Size effect analysis of peak shear strength on rock jointsAbstract:
Because of the unrepeatable of rock mechanics test, it is very difficult to carry out laboratory test of peak shear strength of rock joint surface for the analysis size effect. In view of this, firstly, we obtained the morphology data of the joint surface by 3D scanning technology, and then made the molds of the joint surface using 3D Printers. Secondly, On this basis, we poured a batch of different sizes structural interview pieces, and carried out the direct shear test under 4-stage normal force. Finally, to make up for the deficiency of specimen size and normal stress in laboratory test, we employed PFC2D software to carry out the numerical test of shear strength for the size effect characteristic. The results show that:① 3D scanning and 3D printing technology can accurately realize the size effect of peak shear strength on joint surfaces. ②With the size increase of the joint surface, the peak shear strength increases first and then decreases. That is, the peak shear strength of the joint surface has both positive and negative size effects. ③ The results of direct shear numerical tests of three different types of Barton standard profile show that the size effect characteristics of peak shear strength of joint surfaces are related to the roughness degree.
- 1
Study on optimization of mining method and production system In deep development of Huangshan South copper-nickel mineAbstract:
Natural caving method was used in the original mining of Huangshan South Copper-nickel mine, which resulted in large ore loss and dilution and poor economic benefits. Moreover, the deep underground production system below the middle section of 455m had not yet been formed, which seriously affected the continuous normal production of the mine. On the basis of analyzing the technical and economic characteristics of mining, new mining methods were determined. According to the present situation of mine production and engineering, the best deep exploitation scheme was determined on condition of Detailed technical and economic comparisons, and the deep ventilation system, drainage system, high pressure gas and water supply system were determined. The total investment of the project was 99,659,400 yuan, the average annual operating income of the project after completion was 19,519,600 yuan, the net profit was 39,517,500 yuan/year. The research results have certain guiding significance for the production and technical reform practice of similar mines.
- 1
Experimental study on the effect of red soil overburden characteristics on radon exhalation from the beach surface of uranium tailings pondAbstract:
Covering is the main method to control the beach surface of uranium tailings reservoir. The change of radon exhalation rate on the beach surface of uranium tailings pond was observed by adjusting the properties of red soil covering layer (thickness, compactness, etc.), and the relationship between the thickness and compactness of overburden and radon exhalation rate and radon reduction coefficient was discussed based on the results of covering experiment. The results show that: when the compaction degree is 0.56, the radon exhalation rate gradually decreases with the increase of the covering layer thickness from 0 cm to 20 cm; the radon exhalation rate of the covering layer with the same quality increases from 0.56 to 0.93; with the increase of the compaction degree of the covering layer, the radon reduction coefficient first slowly increases and then increases greatly, which indicates the thickness of the red soil cover layer With the increase of compaction degree, radon diffusion coefficient can be reduced and radon exhalation rate can be reduced.
- 1
Based on "backfill - pillar" bearing effect and reasonable mining parameters researchAbstract:
In recent years, partial filling mining has been widely used as a safe, high-yield and efficient green mining method, and the bearing capacity of "backfill and coal pillar" composite support body is the key to partial filling mining.This paper takes a certain mine as the research object, constructs the mechanical model of bearing and failure of composite support structure, explores the process of co-bearing action of composite support body, and Flac3D to simulate the stress change and subsidence rule under caving mining and partial filling mining.The research results show that:（1）The relationship between horizontal stress σx and height H is cubic and width L is a quadratic. The relationship between vertical stress σy and height H is only quadratic. The shear stress τxy has a quadratic function relation with height H and a linear function relation with width L.（2）Through theoretical calculation, the reasonable partial filling mining parameters of 22m for mining and 16m for filling were obtained.（3）Through numerical simulation verification, the theoretical calculation results are basically consistent with the numerical simulation results, the stress concentration coefficient of the composite support body decreases by 69%, and the ground surface basically does not sink. The research results provide theoretical basis for partial filling mining, and have reference value for domestic large area "three lower" pressurized coal mining, residual coal mining area and ecological environment protection in mining area.
- 1
Numerical simulation of the influence of the position of high drainage roadway and the change of negative pressure on the spontaneous combustion oxidation zone in the goafAbstract:
In order to study the influence of the location of high drainage roadway and the change of negative pressure on the distribution of spontaneous combustion "oxidation zone" in the goaf, numerical simulation was carried out through Fluent modeling. The changes of spontaneous combustion parameters and the range of oxidation zone in goaf under five kinds of high extraction roadway positions and five kinds of negative pressure of 1000 ~ 5000 PA was simulated respectively. In addition, the changes of oxygen concentration and the distribution of spontaneous combustion oxidation zone in the area on the inlet and return sides of the goaf under the influence of two factors are studied. The results show that the change trend of the oxygen concentration on the air inlet and air return sides of the goaf is the same, and it is less affected by the change of the location of the high extraction roadway and the negative pressure. The distribution of the oxidation zone changes with the change of the spatial position of the high-extraction lane. At position 5 (L is 40 m, H is 35 m), the oxidation zone is the narrowest, and at position 4 (L is 30 m, H is 35 m) the oxidation zone is the widest. On both sides of the goaf inlet and return air, the size of the suction negative pressure is positively correlated with the distance between the working face and the oxidation zone, and there is no uniform rule between the suction negative pressure and the width of the oxidation zone.
- 1
Study on timing sequence and location selection of roadway excavation in island working faceAbstract:
In order to make the whole mine faster and more efficient and to realize the coal mining with higher production rate, the island working face often appears in the mine production.The design of working face mining sequence will often appear island working face as the final mining.The mining problems also include three problems, such as the concentration of air pressure, the difficulty in determining the excavation location and the relatively high excavation time and risk coefficient.Friends all the mine in shanxi coal mining process, 60102E working face three face face is empty, the three sides of the 60102E working face goaf roadway excavation, after the coal seam coal goaf mining, geological conditions, adjacent empty time interval and preparation work before roadway as well as in economy, technology, safety consideration, finally decided to adopt the roadway drivage advancing sequence and 60101E working face, and the arrangement of return air roadway transportation lane position.
- 1
Analysis of CEPPA to suppress the thermal characteristics of coal spontaneous combustionAbstract:
In order to study the effect of 2-carboxyethylphenylphosphinic acid (CEPPA) on the spontaneous combustion characteristics of coal, the original coal sample and the inhibitor concentration of 5%, 10%, 15%, and 20% of the inhibitor were prepared. The temperature-programmed-gas chromatograph combined experiment was used to compare and analyze the CO concentration versus temperature curve of 4 different concentrations of inhibited coal samples during the spontaneous combustion and oxidation process to obtain the optimal inhibiting agent concentration. Combined with the simultaneous thermal analysis experiment, the thermal weight loss characteristics and heat release characteristics of the raw coal sample and the best inhibited coal sample are compared and analyzed, and the inhibition effect of CEPPA is analyzed. The results of temperature-programmed oxidation experiments show that the coal sample added with 15% CEPPA has the smallest CO concentration during the heating process, and this concentration has the best effect in inhibiting spontaneous combustion of coal. The experimental results of synchronous thermal analysis show that CEPPA at a concentration of 15% can increase the characteristic temperature of coal spontaneous combustion (dry cracking temperature, ignition temperature and burn-out temperature, etc.), and the value of the inflection point of the DSC curve of the best resisted coal sample is obviously lagging. The heat release is 104.83 J/g less than that of raw coal.
- 1
Stability Evaluation of Roadway Surrounding Rock based on PCA-Fuzzy-PSO-SVMAbstract:
The stability evaluation of roadway has always been a hot and difficult point in mining engineering research. The combined application of PCA-Fuzzy-PSO-SVC can establish the stability evaluation model of roadway surrounding rock, which provides a new method for the stability evaluation of roadway surrounding rock. Among the many factors affecting the stability of the roadway, principal component analysis (PCA) and support vector machine classification method (SVM) were used to integrate the complex influencing factors of surrounding rock into several key indicators, and the influences of various variables on the roadway were characterized in this main way. Fuzzy evaluation method can Fuzzy principal component factor, so as to avoid inconsistency of data scale. Particle swarm optimization (PSO) is used to optimize the classification parameters of support vector machine and the trained evaluation system is applied to practice. Based on this, this paper aimed at jinfeng gold mine roadway surrounding rock complex situation, selected 24 groups of data of surrounding rock as the training sample, and the forecast of 6 sets of data, for the prediction of roadway surrounding rock stability, the results show that PCA method - Fuzzy - PSO - SVC used in jinfeng gold mine of predicting the stability of surrounding rock with high precision, reliable classification results, can be used as the research on the stability of roadway surrounding rock an effective new way.
- 1
Risk assessment of gas explosion based on improved AHP-SPAAbstract:
In order to evaluate the risk of gas explosion in coal mines，accident tree (FTA)，analytic hierarchy process (AHP) and set pair analysis (SPA) are used，considering human factors，management factors，environmental factors，and equipment factors. With 22 indicators including gas emission in the goaf，spontaneous combustion of coal，and explosion-proof failure of machinery，a gas explosion risk assessment model was established，and the model was verified through actual cases. Research shows that the first-level indicator equipment and management factors have the greatest impact on gas explosions，and the environmental factors have the least impact；the secondary indicators have a greater impact on gas explosions by illegal blasting，smoking，gas gushing from goafs，machine explosion-proof failures，and electrical short circuits.
- 1
Aaptive RSSI Algorithm in Underground Space Research Personnel Positioning MethodAbstract:
Internal environment of underground space considering the complicated structure, the signal transmission caused by the loss is big, easy to have a reflection, refraction and multipath effect, simple using RSSI trilateration localization algorithm itself positioning accuracy is not high, in order to improve the personnel accurate positioning, raising the level of intelligent in positioning system. This paper introduces the basic principle of received signal strength indicator (RSSI), expounds the Trilateration method (Trilateration) based on RSSI localization algorithm principle, put forward the adaptive RSSI trilateral measuring method, by adopting CC2430 chips, and the practical application in the personnel positioning of urban underground space. Simulation practice, the author found out that the adaptive RSSI trilateral measuring legal effect is significantly improved, position error within the 1.2 m, fully meet the demand of urban underground space positioning; When the beacon nodes (including the introduction of third-party beacon) accounts for 12.5% of total beacon node localization process can be stabilized. So the improved algorithm to improve the level of safety management personnel in the urban underground space intelligent has important significance.
- 1
Experimental Study on Ultrasonic Atomization Performance Based on The Characteristics of Inhibitor SolutionAbstract:
Goaf inhibitor for the ultrasonic atomization agent was accepted gradually in the aspect of prevention and control of coal spontaneous combustion, in view of the ultrasonic atomization affected by the solution of physical factors and cause atomization effect change, based on the ultrasonic cavitation and conduction theory, using the atomization effect test device, test solution, viscosity and the surface tension of the solution level factors for atomization flow and the influence of atomized particle size.The results showed that the atomized particle size increased with the increase of viscosity, and the relative size range decreased by 0.42, and the particle size distribution was more uniform.There was a linear relationship between the surface tension of the solution and the atomization flow. With the decrease of the surface tension of the solution, the atomization flow increased from 25.3g/min to 32.0g/min, and the atomization effect was significantly improved.The atomization flow decreases with the increase of solution viscosity and disappears when the solution viscosity is greater than 14.81 .As the height of the liquid level increases, the atomization flow first rises and then falls. When the maximum value is 7cm, the atomization flow is 30g/min. At this time, the height of the liquid level is near the maximum ultrasonic energy density and the ultrasonic cavitation is strong.The results of variance analysis showed that viscosity, surface tension and liquid level height had significant influence on the atomization flow, and the influence degree distribution was as follows: liquid level height > viscosity > surface tension.
- 1
Selection of Optimal Flocculant for Whole Tailings and Flocculation NMR AnalysisAbstract:
According to the characteristics of the whole tailings of Sanshandao Gold Mine, a static sedimentation test of the whole tailings and a flocculation sedimentation test with different molecular weight flocculants were carried out. The height of the clarified liquid level and the sedimentation speed were used as evaluation indicators to select the optimal flocculant. And analyze the difference in porosity and pore size distribution of tailings flocs (the flocs in contact with the supernatant, the flocs at the bottom of the measuring cylinder and the interlayer flocs between the two) at different settlement heights by nuclear magnetic means, and explore the pore structure of the flocs feature. The results show that the settlement effect of tailing mortar with ZYZ flocculant is the best. The porosity and pore size distribution of floc particles under different settlement heights are also different. As the sedimentation height increases, the porosity of the floc particles closer to the bottom becomes smaller, and the distribution of small pore particles increases. The settlement speed and settlement height of natural settlement are both smaller than flocculation settlement, and the porosity of the tailing mortar after natural settlement is much smaller than the porosity of flocculate particles in flocculation settlement.
- 1
A DAMAGE CONSTITUTIVE MODEL OF BACKFILL CONTAINING RUBBER POWDER AND EXPERIMENTAL RESEARCHAbstract:
The backfill containing rubber powder is used for mine filling, which can solve the problem of mill tailings and waste rubber; Based on the damage mechanics theory and the Weibull statistical distribution theory, the damage constitutive model and damage evolution equation of the backfill containing rubber powder were built, and the law of damage evolution of the backfill containing rubber powder under load was explored; The correctness of the established model was verified by carrying out unconfined compression of dry and wet samples containing rubber powder. Based on the results of tests, several conclusions can be drawn. It can be seen that the theoretical curve of the damage constitutive model and the strength criterion fit the experimental results well, which verifies the correctness of the proposed models. The addition of rubber powder increases the plasticity of the backfill and increases its peak post-stress, and the plasticity is more obvious in the wet backfill, but the rubber powder-containing backfill will sacrifice certain strength while obtaining better ductility; The rubber powder will aggravate the damage evolution process in the wet backfill, and the damage accumulation rate will change from fast to slow, but it will weaken the accumulation of the load damage in the dry backfill.
- 1
Water plugging technology of adit grouting in water-rich surrounding rockAbstract:
Aiming at the problem of seepage around the surrounding rock in the auxiliary adit of Hejiata Coal mine, the method of geological radar and borehole peep was used to detect the crack damage in the surrounding rock of the roadway, and the causes of the damage and leakage in the wall of the adit were obtained. According to the damage detection results of surrounding rock, the grouting water plugging technology scheme of deep and shallow hole combination is formulated, and the three grouting technologies of cavity filling, fracture sealing and structural reinforcement are implemented in the wellbore of the outlet section. After field application, the grouting effect was retested by GPR. The retest results showed that the repair rates of minor cracks, medium cracks, serious cracks, general water-rich cracks, cavities and severe water-rich grouting were 52%, 33%, 73%, 77%, 100% and 100%, respectively. The water seepage disaster in the adit was obviously controlled. The grouting water plugging technology in the auxiliary adit of Hejiata Coal Mine has a certain guiding significance.
- 1
Experimental study on optimization of microbial curing tailing effect by NBPTAbstract:
In order to optimize the microbial-induced heterogeneity of calcium carbonate deposition (MICP),try urease inhibitor NBPT optimized backfilling materials where reinforcement, namely in the process of microbial grouting reinforcement, by adding the inhibitor NBPT, short-term suppression area of the reinforcement effect, thus optimize the grouting reinforcement, and through the contrast test, the strengthening effect of research where it. The experimental results show that the addition of inhibitor NBPT can improve the reinforcement strength of microbial grouting. When 1% NBPT is added, it can effectively inhibit the growth of Bacillus pasteurella for 8 hours; when the inhibitor content is 1.5% and 3%, the inhibition time is 20h and 48h respectively. NBPT was applied in layers to the sand column reinforced by microbial grouting, and the cohesion and internal friction angle were increased by 8.22% and 4.10% after grouting.
- 1
Research on the influence of wind speed on the countercurrent migration of outburst gasAbstract:
In order to study the countercurrent migration process of outburst gas in the tunnel under the influence of wind speed, determine the mathematical model of underground outburst gas migration. Taking a section of underground through tunnel in a coal mine in Guizhou as a prototype, use Fluent software to establish a geometric model and set settings Under the same working conditions, simulate the influence of different wind speeds on the countercurrent migration process of outburst gas, analyze the changes of the peak gas concentration at different time and different measuring points, and take Honghui Coal Mine as an example for field verification. The research results show that: after the outburst occurs, there is a gas backflow phenomenon in the roadway; the influence range of gas in the roadway increases with the increase of the propagation distance, and the peak gas concentration decreases with time in a power function; the higher the wind speed, the gas The faster the gas is discharged from the roadway, the smaller the peak gas concentration, and the farther away from the outburst point, the slower the gas concentration will reach the peak. The simulation results are reasonable by field shooting.
- 1
Study on The Thixotropic Characteristics of The Unclassified-tailing Mortar in Different Shear ModesAbstract:
In order to explore the thixotropic characteristics of the cementing filling slurry with tailings, the rheological parameters of an unclassified-tailing were tested under the conditions of constant shear mode, annular shear mode and step shear mode.The results show that the shear stress and apparent viscosity decrease gradually until stable under constant shear mode, and the yield stress of slurry increases with the increase of shear rate but the plastic viscosity decreases.Under the cyclic shear mode, the shear stress decreases as a whole regardless of whether the shear rate increases or decreases，but the law of plastic viscosity change is opposite of the change of shear rate..In the terraced shear mode, the tailings slurry will enter the elastic change stage again with the shear rate and then enter the stress relaxation stage.The thixotropic law of tailing slurry is explained, which is of certain guiding significance to the field pipeline transportation of mine.
- 1
Design and Characteristic Analysis of Electro-mechanical Converter for Mine-used Electromagnetic ValveAbstract:
Aiming at the mine electromagnetic pilot valve on the hydraulic support, two voice coil motors with different yoke structures were proposed as the electromechanical converter on the pilot valve, and the dynamic mathematical model of mechanical, electrical and magnetic coupling of voice coil motor was established. Two different mechanical structures were analyzed and compared by Ansoft Maxwell, the force displacement characteristics of the voice coil motor under the structure, and the magnetic circuit and air gap magnetic density of the two were analyzed. It is concluded that the force displacement characteristics of the voice coil motor with radial yoke were better, and the electromagnetic force peak value can reach 5.2N, which was 24% higher than that of the another structure. Furthermore, the static characteristics of the structure were analyzed, and the influence of the thickness of the radial yoke, the air gap and the width of the yoke on the electromagnetic force were studied, the results show that?its effectively improve the electromagnetic force, and provide an important basis for the selection and design of electromechanical converters for mne-used electromagnetic valve.
- 1
Experimental Study on Admixture Reduction of Filling Slurry DensityAbstract:
In deep mining filling, reducing the density of the slurry can effectively reduce the pressure of the pipeline and reduce the risk of tube explosion. The effect of sodium dodecyl sulfate (K12), sodium rosin and sodium alcohol ether sulphate (AES) on the slurry density of a gold deposit was studied. The results show that: 1. When the amount of foam stabilizer was 10%-15% of the amount of air entraining agent, the effect of reducing density was better; 2. with the increase of air entraining agent, the density of slurry decreases, and the K12 of 0.8% powder decreases best, which can reduce the density from 1.74 g/cm3 to 0.70 g/cm3, with the increase of dosage, the density of slurry increases.
- 1
Spatial pattern of the green development of mining industry in the Yangtze River Economic Belt and its driving mechanismAbstract:
The green development of mining industry is an important part of the economic green development and also an important content of the implementation of ecological civilization construction of the Yangtze River Economic Belt. In this paper, the evaluation index system of mining green development and comprehensive index method based on the "Pressure-State-Response" model were adopted, provincial mining green development patterns and the internal and external driving factors were analyzed, and the driving mechanism framework of mining green development in the Yangtze River Economic Belt was established. The results showed that: (1) In general, the level of the green development of mining industry in the Yangtze River Economic Belt was gradually increasing from the west to the east; in the three sub-indexes, the level of green development state is the highest, and the level of green development response is the lowest. (2) the internal driving factors of green development of mining industry were the ecological environmental pressure, environmental protection level and policy response in the eastern region while the mining development pressure and ecological environment pressure in the central region, but all internal driving factors had the restrictive effects on green development of mining industry in the western region; (3) six external factors, economic development, urbanization, industrial structure, scientific and technological innovation, opening-up and marketization, had positive impacts on the spatial pattern of green development of mining industry in the Yangtze River economic belt; (4) in view of the imbalance of regional development in the eastern, central and western regions, this paper puts forward countermeasures and suggestions on reducing the pressure of green development of mining industry, and improving the state and response levels of green development.
- 1
STUDY ON HIGH-EFFICIENCY MINING METHOD OF STEEP COMPLEX THIN OREBODYAbstract:
Fenghuangshan silver ore body belongs to the steeply inclined thin ore body with complex occurrence. The ore body was originally mined by shallow hole shrinkage method, which has the problems of low production capacity, poor safety conditions and frequent accidents. In order to mine the ore body safely and efficiently, based on the production status and mining conditions of the ore body, and according to the production capacity, loss rate, dilution rate and other indicators, the open stope is divided into several sections Four mining methods are compared and analyzed, such as back filling mining method, raise mining method, panel mechanized filling method and medium deep hole shrinkage method. The sublevel open stoping and subsequent filling mining method with obvious advantages is selected as the improvement scheme. The industrial mining test is carried out in I-① orebody of 180m middle section of the mine, and good mining results are obtained.
- 1
Experimental Study On The Optimal Ratio Of Tailings Paste FillingAbstract:
In order to study the effect of lime-sand ratio, slurry concentration and curing time on the performance of filling slurry, the optimal ratio of filling slurry was determined. Combined with the actual filling of a fluorite ore paste, using full tailings and ordinary portland cement as the filling material, three factors and three levels orthogonal test were used to study the three factors, and the optimal method was used to select the best Mix ratio. The results show that: the slump increases with the lime-sand ratio, showing a trend of decreasing first and then increasing. The slump changes inversely with the slurry concentration; the most important factor affecting the full tailings filling body is the lime-sand ratio; recommended The optimal filling ratio is: lime-sand ratio 1: 4, slurry concentration 75%, curing age 28 days.
- 1
Research on the regularity of Mine pressure in fully mechanized top coal caving face through oblique crossing reverse faultAbstract:
In this paper, the research on the law of Mine pressure through oblique crossing reverse fault in the fully mechanized top coal caving face of hard roof is carried out. Establish a geometric model for reverse fault in fully mechanized caving face to obtain the calculation formula for the leading slope distance of pick the top without breaking the top .Combined with the specific geological conditions of a mine, the method of numerical simulation and on-site measurement was used to analyze the regularity of the mine pressure over the oblique crossing reverse fault. The results show that the integrity of the coal and rock mass in the fault area is broke by the structure, resulting to a reduction in the step pressure and strength of the working face during the over-fault period；in the fault area, When the pressure is not periodic, the working resistance of the support in the direction of the working surface forms a single-peak curve with the peak at the fault surface，When the pressure is Periodic, a double-peak curve with a valley at the fault plane is formed；Long downtime will also lead to the occurrence of gangue leakage and coal wall chipping. Safety technical measures need to be formulated to ensure that the working face passes through the fault safely.
- 1
Study on Optimization of Stability Analysis Method for Clay SlopeAbstract:
Since clay slope is often encountered in the construction of highway engineering, various methods are used to analyze the stability state of the clay slope with specific characteristics, thus to optimize the calculation method. By comparing the calculations, the adhesive force plays a greater role than the internal friction angle in the clay slope. The discount ratio K between 1.1 and 1.4 is more reasonable, and the safety factor is about 1.3 under the calculation of different folding and subtraction methods. After comprehensive analysis, to reflect the evolution law of strength parameters during calculation, it is recommended to analyze the stability of clay slope employing the non-equidistant proportion-associated folding method if the experiment is allowable, if not the critical curve method.
- 1
FLOTATION TEST RESEARCH WITH ASSISTANCE OF HYDRODYNAMIC CAVITATION BASED ON RESPONSE SURFACE METHODAbstract:
The experiment of coal flotation with hydrodynamic cavitation pretreatment in the absence of flotation agent was conducted based on the Box Behnken Design (BBD) response surface method. The effect of velocity of throat(A)、areation rate(B)and number of cycles(C) on concentrate ash content and combustible were mainly investigated. The test results shows that the areation rate is the most significant factor while the factors are interactively,the non-agent hydrodynamic cavitation pretreatment increases the collectability of flotation while the selectivity of flotation is not be affected. The optimum technological condition as follows：velocity of throat is 16 m/s,areation rate is 2.3%,number of cycles is 5.3 times,the concentrate was obtained which ash content and combustible are 12.03% and 85.89%,respectively. Compared with conventional flotation,combustible could be improved by 11%,the consumption of kerosene could be saved by 50% in the same flotation result.
- 1
Research on Oxygen Consumption Rate of Leftover Coal Based on Large-scale Simulation Experiment of Coal Spontaneous Combustion in GoafAbstract:
In order to study the relationship between oxygen consumption rate and temperature in the process of spontaneous combustion of the leftover coal in the goaf, a large-scale simulation test study of spontaneous combustion in the goaf was carried out on the No. 8 coal at 8059 working face of Yaoqiao Coal Mine of Datun Coal Company. Relying on the large-scale simulation experiment system for coal spontaneous combustion in the goaf, considering the occurrence status of the coal in the actual goaf, heat storage environment and other factors, design and construct an experimental device for the coal spontaneous combustion process in the goaf to simulate the coal in the goaf under similar simulation conditions The process of spontaneous combustion of coal under coal. Data such as the temperature of the remaining coal, the production of CO, CO2, CH4, and the consumption of oxygen during the test are recorded through equipment such as temperature detectors and gas chromatographs, and the relationship between the oxygen consumption rate and temperature of the remaining coal is analyzed through MATLAB. The results show: In the process of spontaneous combustion of the coal in the goaf, the production of index gases such as CO, CO2, and CH4 showed an increasing trend. The oxygen consumption rate of the coal in the goaf has an approximate exponential function relationship with temperature.
- 1
Effect of the CaO/SiO2 ratio on the properties and heavy metal leachability of lead-zinc tailings glass-ceramicsAbstract:
In this study, glass-ceramics were synthesized from LZT. The effect of the CaO/SiO2 ratio (R) on the crystallization, structure, properties and heavy metal leachability of glass-ceramics was explored. The results showed that the transition temperature (Tg) and crystallization temperature of basic glass first decreased and then increased as R was increased. The main crystalline phase of the glass-ceramics is albite; however, the increase in R hindered the crystal growth of albite but facilitated the formation of diopside, gehlenite and nepheline crystals. When R = 0.50, the glass-ceramic samples obtained the best comprehensive performance: density of 2.93 g/cm3, compressive strength of 178.85 MPa, weight loss of 2.12% in an acidic solution and weight loss of 1.57% in an alkali solution. The leaching experiment showed that the leaching of Zn and Mn was not sensitive to changes in the CaO/SiO2 ratio but that the leaching of Pb first increased and then decreased.
- 1
Numerical simulation of blasting dust migration in the Meishan iron mineAbstract:
In order to explore the migration law of blasting dust discharged from roadway type stope, this paper is based on a roadway type stope at the level of -330m in the Meishan iron mine. The results show that the distribution of stope wind speed on the vertical section is as follows: "high on both sides, low in the middle, higher on the top than on the bottom, more in than out, and almost no wind near the working face". Within 600s after blasting, dust concentration decreased rapidly. Blasting dust in a horizontal spread significantly affected by wind flow field, the upper part of the stope dust diffusion velocity is greater than the lower part of the dust, the lower wind flow, stope at the bottom of the dust concentration is higher than the upper dust concentration for a long time, sometimes in a corner near the working face until the end there is still a small cloud of dust dirt cannot of eduction. The wind speeds of 2m/s and 3m/s are the most favorable for blasting dust discharge.
- 1
An event-driven on-line monitoring system for trucks fuel consumption in open-pit minesAbstract:
In view of the inflexibility of truck fuel consumption monitoring in open pit mine, an event driven on-line monitoring system for truck fuel consumption is designed. Based on the traditional truck scheduling system, the system proposes an event driven truck state transition model. On the basis of integrating the information of truck engine, positioning and lifting, it gives the trigger events required for each state transition, and then gives the fuel consumption of the stuck vehicle in the state after the state is finished. At the same time, combined with the road information, the distance road matching model is adopted After the road matching of truck tracks, the fuel consumption of trucks on different roads is further monitored. The field test results show that the delay time of updating fuel consumption calculation results can be controlled within 2 seconds when the basic data sampling period is 1 second.
- 1
Study on Index Gas Based on Similar Simulation Experiment of GoafSpontaneous Combustion and Temperature Programmed ExperimentAbstract:
In order to improve the reliability and accuracy of coal spontaneous combustion prediction in goaf, based on coal spontaneous combustion simulation experiment, this paper simulated the spontaneous combustion process of No.8 coal goaf in 8059 working face of Yaoqiao Coal Mine of Datun coal company under the condition of heat source, and investigated the spontaneous combustion process of goaf coal in low temperature oxidation The variation law of various gas products in the process. And through the program temperature increase experiment, the comparative analysis of the index gas generated during the low-temperature oxidation of coal was carried out, and the changes of CO, CO2, CH4, C2H4, C2H6 gas with the temperature of the heat source were obtained. CO is regarded as the main indicator gas to predict the spontaneous combustion of the residual coal in goaf, and C2H4 and C2H6 are used as auxiliary reference indexes.
- 1
Research on Overlying strata Destruction and Instability of Underground Mining Stope in Different Inclined Ore BodyAbstract:
The stability of surrounding rock and overlying strata is one of the main factors affecting mine safety production. In order to explore the destabilizing characteristics of overlying strata in stope during the underground mining with different angle ore bodies, the 20 angle and 50 angle model was established by PFC2D to research the internal stress changes and crack propagation laws of the underground stope overlying strata during mining, and compared it with similar models. The results show that: (1) when the mining space is small, the overlying strata will undergo four stages of unloading-raising-fluctuation-stabilization, the smaller of the inclination angle, the longer internal stress stabilization time of the overlying strata at the same distance from the stope, and more likely to be secondary unloading. (2) When the mining space is small, a small amount of micro-cracks are generated in the surrounding rock and adjacent overlying strata, and the crack propagation is arched, which tends to penetrate through the upper and lower ends of the stope. After multi-step mining, the cracks between the surrounding rock and overlying strata of each stope penetrated each other, and gradually propagate to the surface, resulting in instability of the stope. (3) The smaller inclination angle, the larger tensile zone of the overlying strata and the tensile effect more obvious, resulting in more cracks, faster crack propagation rate and faster penetration. The 20 angle orebody model mining has a greater impact on the stability of surrounding rock and overlying strata. This result can provide a theoretical reference for the problems of underground mining pressure control, stope instability and mined-out area collapse during underground mining.
- 1
Optimization of Mining and Mineral Processing Industrial Site in a Mine under Complex Logistics ConditionsAbstract:
The selection of mining and mineral processing industrial site directly affects the production scale, logistics transportation, production operation and economic benefits of mines. There are some problems in the industrial site selection of the subordinate mines of a mining company in Guizhou, such as complex product processing technology, tailings storage, land acquisition, complex logistics and existing projects. In order to select the best mining and mineral processing industrial site,the mathematical model of site selection is established. Firstly, the logistics relationship of the three primary schemes is analyzed. In addition, the general layout, mining, mineral processing, mining machinery, power supply, water supply and drainage and other specialties were configured. Each scheme was designed in detail, and the investment, operating costs, net present value, advantages and disadvantages were compared and analysed. Finally, scheme 1 (centralized layout of main shaft and mineral processing in mining area B) was determined as the preferred scheme. The research process and method can be used for reference in the selection of mining and mineral processing industrial sites under complex logistics conditions.
- 1
Blasting Vibration Prediction System Based on BP Neural NetworkAbstract:
In order to predict peak of the blasting vibration velocity in different blasting conditions, develop prediction program that can run independently, using the BP neural network and MATLAB, selecting the maximum charge quantity, hole depth, the horizontal distance, vertical distance and unit consumption as input layer, the output layer is the peak vibration velocity collected by the vibration meter, a set of blasting vibration prediction system is established. The results show that the average error of Sadov's formula is 20.556% and the maximum error is 39.87%, the average error of the prediction system was 6.594% and the maximum error was 10.67%, the prediction accuracy of the prediction system is improved obviously.
- 1
Study on the failure mode and acoustic emission characteristics of sandstone under initial damageAbstract:
In order to study the influence of surrounding rock damage under cyclic impact load on tunnel stability during blasting excavation, using damaged sandstone under uniaxial compression test and supplemented by acoustic emission equipment for the whole monitoring. The strength characteristics acoustic emission characteristics and failure modes of sandstone under different damage factors were studied. The results show that the rock damage factor is negatively correlated with the compressive strength, and the damage factor can be used to predict the compressive strength of undamaged rock. When the damage factor is 0-0.3, the number of AE events is generated near the stress peak, while when the damage factor is 0.3-0.7, the number of AE events is generated earlier than the stress peak The newly formed sandstone with no initial damage has a more uniform distribution of damage while the sandstone with initial damage continues to develop along the existing cracks. With the increase of damage, rock failure changes from split failure to shear failure
- 1
Technical Characteristics and Lifting direction of Backfill Mining for Large Diameter Long- Holes in Unstable Rock in Zijinshan Gold and Copper MineAbstract:
zijinshan gold and copper mine is a famous oversize copper mine at home and abroad.Underground mining adopts post-filling method with high production efficiency, low production cost and good safety.In this paper, in order to obtain good technical and economic effects, a number of innovative technologies have been adopted in zijinshan gold and copper mine under the condition of less stable ore and rock, and the main technical characteristics of the application of the mining process in the bad environment have been formed.At the same time, the paper puts forward the development direction and improvement plan of the mining method according to the development trend of mining technology.
- 1
Study on the Image Identification in the Application of the Intelligent DrillingAbstract:
To solve the problem that the coal and rock can not be automatically identified in the returning slag from drilling,identification method and selection of feature to analysis of coal and rock were proposed by identify the gray-scale feature of the coal and rock images of the returned slag from the borehole. The images of the drilling slag samples were pre-processed by the extraction of lightness components, denoising and image enhancement.The histogram-aided gray threshold was used to analyze the images and the confirmed best threshold by the OTSU was used to separate the images.The method of the gray threshold was used to identify the segmented images. The results show that the images of the samples can be accurately identified by this method.
- 1
Experimental study of the optimal selection and compounding of surfactant on the Wetting Effect of Coal DustAbstract:
In order to study the wetting efficiency of the compound surfactant on coal dust with different particle sizes, three coal dust samples with different particle sizes in 3-1 coal seam of Hongqinghe Coal Mine were subjected to settlement experiments. It is found through the selection of surfactants in the monomer sedimentation experiment that the anionic surfactant has better wetting ability for coal dust than nonionic and zwitterionic surfactants, and then the compounded sedimentation experiments are carried out on the four selected surfactants. Adding anionic surfactant makes the wettability of 0.04% fast-permeable T solution to coal dust significantly enhanced; the combination of zwitterionic surfactant and fast-permeable T solution has little change to the wettability of fast-permeable T solution; The non-ionic surfactant is compounded with the fast-permeable T solution, which greatly improves the wetting efficiency of the fast-permeable T solution for small-diameter coal dust.
- 1
MINING METHOD STUDY OF TABULAR, THIN OREBODY FOR A PLATINUM MINE, SOUTH AFRICAAbstract:
South African Bushveld Complex is the most important orebody in the world. It consists of three types of reef, i.e. Merensky, UG2, and Platreef. Both two reefs, Merensky and UG2, which are mining for now, are tabular thin orebody. It is very difficult to mine such reefs because of its tabular and thin orebody. So far most of mines are still labor intensive, and a few mines are mechanized mining. For a platinum mine, it employs vertical shafts to access its reefs, conventional stoping and hybrid stoping for both Merensky reef and UG2 reef respectively. Mining both two reefs concurrently, so some drives can be shared. This is benefit for reducing dilution rate and losses, improvement of recovery and cost-effective.
- 1
Research and Practice of Optimization of Woxi Kengkou Deep Well Mining MethodAbstract:
The center of gravity of the mining in Woxi pit has been moved down to the deep. The existing vertical stripped waste rock cemented filling mining method has caused problems such as low production efficiency, hidden safety hazards for operators, and low filling quality in the face of the complex environment of deep well mining. Issues were analyzed from the technical, management and economic perspectives, the mining methods were optimized from the aspects of high-efficiency equipment and advanced filling technology, and on-site industrial test was carried out. Test has shown that after the optimization of mining methods, The production capacity of a single stope is 45~70 t/d, the efficiency of the table shift is 150~200 t/d, the dilution rate is 8%, the loss rate is 5%, and the filling efficiency is 200 m3/shift .The main technical and economic indicators have been significantly improved, which can be used for reference by mines of the same type.
- 1
Effect of curing age on mechanical properties and damage characteristics of filling bodyAbstract:
In order to study the influence of curing age on the mechanical properties and damage law of tailings cemented backfill, a uniaxial compression test was carried out on the cemented tailings backfill of different curing ages on the RMT-150C rock mechanics test system; The mechanical parameters and stress-strain curves of the cemented backfill were analyzed, and the failure mechanism of the filling during the test was analyzed in detail. The damage evolution and damage constitutive equations of the cemented backfill under different curing ages were derived. The test results show that: The elastic modulus and secant modulus are positively correlated with the curing age, and all follow the exponential function curve growth law. When the lime sand is relatively low, the strengthening effect of the curing age on the average stiffness of the backfill is more obvious; The peak deformation modulus and toughness index increase exponentially with the increase of the curing age, the more significant the toughening effect of the curing age on the backfill with the larger the ratio of lime to sand; The peak stress damage value of the filling body has a good exponential correlation with the curing age; With the extension of the curing age, the overall damage value grows slower. The side shows that the shorter the curing age, the more severe the damage process of the cemented filling body is, which reflects the low bearing capacity of the cemented filling body; Based on the change law of damage value and stress value, it can be known that the damage evolution mechanism of the filling body under uniaxial loading can be divided into four stages: initial damage, stable development of damage, acceleration of damage and damage
- 1
Optimization of Deep Weel Cooling Method Based on Multi-objective DecisionAbstract:
In order to improve the scientificity and accuracy of deep well cooling method selection, this paper proposes an optimal method based on multi-objective decision making. The study uses the "expert consultation method" to determine the five evaluation indicators for the optimal decision, and uses the relative importance sequence matrix method to obtain the weight of each indicator. Taking the original surrounding rock temperature and mining depth as the reference standard for selecting a cooling scheme, 28 mines with complete index data were selected, and multi-objective decision calculations were performed on their evaluation index values and weights. Taking the scheme with the smallest deviation between the calculated result and the ideal result as the preferred scheme, the corresponding optimal cooling method was obtained at different original rock temperatures and mining depths. This study can effectively improve the scientific and effective decision-making of high-temperature mine cooling methods.
- 1
Study on the influencing factors of gas-containing coal adsorption characteristicsAbstract:
In order to study the influence of gas-containing coal composition and pore structure parameters on coal adsorption capacity, the pore structure of five coal samples was tested by mercury intrusion test, and the specific surface area, average pore size, porosity and fractal dimension of gas-containing coal were studied. Four kinds of pore structure parameters, such as the number, were analyzed, and the relationship between the composition of gas-bearing coal and the pore structure parameters on adsorption capacity was analyzed. Studies have shown that: the specific surface area of moisture and volatile matter has a quadratic function relationship with the limit adsorption capacity (VL), ash and VL are negatively correlated, and average pore size and porosity are positively correlated with VL. Langmuir pressure (PL) increases with the increase of ash and volatiles, decreases with the increase of the average pore size and porosity, and has a quadratic function relationship with the specific surface area. Coal samples have different fractal characteristics at different pressure stages, so they have different fractal dimensions D1 (r<10 nm) and D2 (r>10 nm). Both D1 and D2 are greater than 2.9, and the fractal characteristics are obvious. VL increases with the increase of D1 and decreases with the increase of D2. The relationship between fractal dimension and PL is not obvious.
- 1
Research on Application of a New Cementitious Material in Songxian Shanjin Mining Co., LtdAbstract:
Aiming at the problems of high filling cost, low filling strength and insufficient supply of cementitious materials in Songxian Shanjin Mining Co., Ltd, residue (C material) is used instead of cement, and Laboratory and field application studies were carried out. The results show that when the slurry concentration, ratio and curing age are the same, the uniaxial compressive strength of the test block cemented with residue (C material) is 2-4 times that of cement, and the bleed and initial setting are better, which is conducive to recovery and filling cycle. When residue (C material) is selected for filling the false bottom, cement surface and general cement material on the site, the cement-sand ratios of 1: 6, 1: 7 and 1:14 respectively can meet the strength requirements. Under the same strength condition, the amount of residue (C material) is 1/2 to 2/3 of cement, and the unit price of residue (C material) is equivalent to that of cement, which can greatly reduce the filling cost. Therefore, the selection of residue (C material) as cementing material not only greatly improves the filling strength, further reduces losses and depletion, but also improves the safety coefficient of mining and the economic benefits of the mine.
- 1
Research on the floor damage characteristics of an upper close coal seam based on numerical simulation analysisAbstract:
To achieve the pressure relief and the permeability improvement of coal seams with high gas and low permeability in the protective seam mining technology, UDEC discrete element numerical simulation software was exploited to research the influence of the mining of the upper coal seam on floor damage, and the influence of floor damage of the upper coal seam on gas migration of the lower coal seam was researched. The research results are stated as follows: A triangle stress-reducing area of the floor behind the working face was produced; The fractured zone in the floor can be further divided into two parts, the tensile failure zone and the yield failure zone, according to the difference of mechanical failure mechanisms; The floor fractured zone caued by the recovery of 2# coal seam promoted the desorption and migration of gas of 3# coal seam, effectively decreasing the amount of gas emission during the recovery of 3# coal seam. Therefore, the security of the working face was ensured.
- 1
Finite Element Analysis of Mechanical Properties of Copper Ore with Different Load Types Based on MarcAbstract:
In order to analyze the mechanical properties of copper mine under different loading conditions, the research basis of structural damage and mining dynamics of copper mine is provided. The copper samples in Baiyin area of Gansu Province were collected, and three different loading methods were applied to the copper samples in MARC software: tension; compression; and Brazil splitting method was used to analyze the change of internal strain rate of copper samples under different loading conditions. At the same time, the relationship between strain rate and strength, modulus of elasticity, incident energy, reflection energy, transmission energy and dissipation energy is analyzed. The results show that the relative growth of modulus of elasticity of copper ore under three kinds of loads is far greater than that of strength. The relative growth of modulus of elasticity corresponding to the three kinds of loads is 2556%, 3084% and 3753%, and the relative growth of strength corresponding to the three kinds of loads is 261%, 582% and 758%. In addition to the Brazilian splitting tensile state, with the increase of strain rate, the incident energy and transmission energy of stress wave increase, the dissipation energy almost remains unchanged, while the reflection energy decreases. At the same strain rate, the results of elastic modulus and dissipation energy in tensile and Brazilian splitting tensile states are smaller than those in compressive states. The research results provide research basis for strain rate research, dynamic analysis and practical engineering application of copper deposit.
- 1
Ventilation technology research of Underground main and auxiliary fan automatically converted into multi-stage fan stationAbstract:
According to the complex ventilation network which is hard to control between the easy ventilation period and hard ventilation period while Multi-level mining in deep mine, the new ventilation technology of Underground main and auxiliary fan automatically converted into multi-stage fan station is proposed, the system condition of the technology is analyzed, and the construction method is presented, the technology is used to optimize the ventilation system of Hubei Sanxin Gold Copper Co.,Ltd. After the transformation, the measured effective air rate is 81.33%, the wind speed qualified rate is 76.32%, fan efficiency is above 88%, the system operating cost decreased by 23.04%, the ventilation problems of Hubei Sanxin Gold Copper Co.,Ltd such as difficult to control, insufficient air volume, reverse air flow, air leakage in the system, large difference in ventilation resistance in the early and late stage, and large installed power were solved successfully.
- 1
Research and Application of Blasting Auxiliary Design System Based on Visual LISP and VBAAbstract:
Aiming at the problems of large-diameter and deep hole stage, such as heavy workload, tedious work, great influence of subjective and objective factors by the designer, easy to make mistakes and so on, based on visual LISP and VBA language programming, establish the blasting auxiliary design system, realize the automatic generation of the current blasting design, the automatic statistics of charge list and blasting material requisition list. The blasting design process and results is easy to control, and the blasting construction are easy to manage. The control degree of blasting is improved., the design time required by this design system is only 30% of the origina blasting design method; create favorable conditions for mine production scheduling, and the blasting design accuracy is high, the error rate is low, which effectively ensures the effect of vertical deep hole blasting.
- 1
DENG Xiao, JIANG Fu-xing*, ZHU Si-tao, LI Jia-jieAbstract:
Aiming at the problems of ground collapse and environmental damage caused by a large number of abandoned mines, combined with the characteristics of the difficulty of urban garbage disposal, the proposed disposal technology of filling the mine deep well abandoned space with urban garbage can effectively play a role in treating waste with waste. Firstly, based on the deep underground disposal of nuclear waste, oil and gas and the experience of underground disposal of waste in Germany, combined with the characteristics of urban waste underground disposal site, this paper analyzes the security protection composition of urban waste disposal system, and finds the key influencing factors of site selection safety. Then, the article evaluates and grades the key influencing factors of site selection, and proposes a multi-factor coupling evaluation method for site selection. Finally, the underground disposal conditions of the 93-05 working face of Jining No. 2 Mine were evaluated to verify the rationality of the main influencing factors and the feasibility of the evaluation method.
- 1
Experiment on flotation of ilmenite with a new anion collectorAbstract:
In order to test the flotation effect of the new anionic collector HL-01 on ilmenite, the single factor condition test and technological process test of flotation were completed with the tailings as raw material from an iron concentrator in Panzhihua. The composition of collector HL-01 was analyzed by FTIR, and the mineral composition of raw ore was analyzed by XRD. Screening analysis shows that the content of -0.074mm grain is 91%, and the content of TiO2 is 19.63%. The optimal flotation conditions of HL-01 are as follows: pulp concentration is 21%, HL-01 dosage is 2600g/t, sulfuric acid dosage is 1600g/t and blowing time is 10min. Under these conditions, TiO2 grade of titanium concentrate is 44.87%, and the recovery is 82.46%. Under the optimal conditions, the flotation technological process of HL-01 ilmenite is tested. Through one roughing and one fine flotation process, TiO2 grade of titanium concentrate is 47.61% and the recovery is 81.97%.
- 1
Research on the structural failure of shock wave of coal and gas outburst to outburst prevention air doorAbstract:
In order to analyze the safety of the anti-outburst damper after the outburst, the failure mechanism of the typical damper caused by the outburst shock wave was studied in combination with fluid dynamics.Based on theoretical derivation, the model of shockwave propagation under coal and gas outburst is obtained, and the overpressure reflected on the damper is given in combination with the industry standard.Based on the industrial experimental data and the relevant impact load equation, ls-dyna software was used to simulate the damper failure under impact load.The results show that the stress of the damper has a consistent correlation with the loading. The central position and the position close to the duct are the weak points of the damper structure. The peak stress reaches up to 204.6Mpa, which is over to the yield limit of Q195 steel,need to be reinforced.
- 1
System Dynamics Modeling and Simulation of Investment Decision Making in Metal Mime ProjectsAbstract:
In the view of characters of systemic, complex, feedback, and dynamic uncertainty in investment decision-making of metal mine projects, taking the traditional method of net present value as the basis and under the guidance of system dynamics theory, this paper studies on the investment decision making of metal mine projects. That is, on the basis of determining the reasonable system boundary, the stock-and-flow diagram is constructed through a causal analysis of the system and the basic equations of system dynamics are determined to realize the complex system modeling of investment decision making of metal mine projects. Then, taking a copper mine invested in Zambia as an application example, the dynamic simulation of the model is completed by using Vensim software. After the prediction and sensitivity analysis of the net present value in this project are carried out, the conclusion that the project is economically feasible is drawn. The results show that the system dynamics simulation model presented in this paper is real and reliable, which has operability and promotion value. The model also provides a new idea and method for investment decision making of metal mine projects.
- 1
Experimental Research on Grouting Reinforcement Characteristics of Sandy Soil LayerAbstract:
Based on the difficulties of shaft construction under the conditions of shallow sandy soil, taking the reinforcement of the main and auxiliary shafts of Shengfu Coal Mine in Ordos, Inner Mongolia as the engineering background, discussed the characteristics of grouting reinforcement in sandy soil. The experiment plan was designed according to three factors and five levels of the orthogonal principle, and the compressive strength, tensile strength, cohesion and the internal friction angle of the sandy soil grouting consolidated body under different water content, mortar-sand ratio and curing time were surveyed and evaluated. Then the correlation between the three factors and the mechanical properties of sandy consolidated body is analyzed. The results of the study indicate that when the water content is 3.4%, the mortar-to-sand ratio is 1:4, and the curing time is 4 days, the mechanical property of the consolidated body is optimal. The influence degree of various factors on the mechanical properties of the consolidated body is as follows: Water content ranks first, mortar-sand ratio second, curing time last, and as the water content increases, the compressive strength, tensile strength and cohesion of the consolidated body decrease, and the mortar-sand ratio is inversely proportional to the internal friction angle.
- 1
Study on dust diffusion simulation and airtight control technology of deep chuteAbstract:
Through the application of hydrodynamics software to the numerical simulation analysis of the unloading process of deep Chute, the distribution of dust concentration after ore pass unloading is obtained. After unloading, the large particles within the particle size range of 1.0×10-3 ~ 7.0×10-4m are the first to settle; the respirable dust with particle size less than 10-6m is the most difficult to settle; the average wind speed of each branch chute is 0.46m/s, 0.83m/s and 1.07m/s respectively, and the impact airflow is positively correlated with the height of ore unloading. According to the actual situation of a mine, it is proposed to install a flip type wind shield at the ore pass unloading opening, combining with the field measurement of the impact gas velocity and dust concentration in the deep ore pass. According to the field test, the overturned wind deflector can effectively reduce the dust concentration at the ore pass discharge opening, and the dust reduction rate can reach more than 90% and the wind resistance rate can reach more than 60%. The closed device can effectively solve the problems of air leakage and air pollution in series, and effectively control the dust produced by ore unloading.
- 1
Study on Stability Control Method of Surrounding rock of Deep shaft Based on Stress Field InterventionAbstract:
With the depletion of shallow mineral resources, China's mine shaft is gradually entering the depth range of 1500~2000m. Meanwhile, the application of deep shaft layout optimization is often very limited, and few studies on controlling the stability of surrounding rock by stress field intervention are reported. This study a high stress of surrounding rock in deep vertical shaft engineering as the background, through comparing various shaft liner maintenance effect of intervention scheme of surrounding rock stress field and stress field distribution characteristics of surrounding rock, it is concluded that in the surrounding rock of principal stress direction annular slot scheme, the stress peak at the inner and outer edges of the shaft liner decreases by 23.16% and 19.33%, respectively. The imbalance coefficient K of the extreme stress on the shaft liner decreases from 3.42 to 1.80, and the stress and displacement are distributed more evenly, and further explores the implementation of tactics of intervention on the stress field of surrounding rock engineering measures. Compared with conventional methods such as thickening the shaft liner and adopting high-grade concrete to deal with the unbalanced high in-situ stress environment of deep vertical shaft, the reasonable stress field intervention scheme provides another solution for the control of high stress surrounding rock in deep vertical shaft.
- 1
Study on Optimization of Coal Pillar Retaining Scheme in Fully Mechanized Caving Mining Section of Spontaneous Combustion Coal SeamAbstract:
It is a common technical problem to determine the width of coal pillar along the gob driving section in the fully mechanized top coal caving face of thick coal seam. The section coal pillar can ensure the stability of the adjacent roadway and isolate the goaf. The existing research mainly focuses on the stability of the surrounding rock, but less on the air leakage and oxidation of the coal pillar in the spontaneous combustion coal seam. In this paper, based on the engineering background of coal pillar in 4103 return air roadway section of class II spontaneous combustion tendency coal seam in Changheng coal mine, the method of combining theoretical analysis and field measurement is adopted to establish the model of coal pillar instability cusp catastrophe. Combined with the theory of stable core area and the theory of limit equilibrium, the reserved width of section coal pillar is obtained. Through the industrial test, the deformation of surrounding rock and the effect of coal pillar fire prevention are monitored. The results show that: (1) the cusp catastrophe model shows that the instability of coal pillar is related to the stiffness ratio of yield zone and elastic core zone. Mechanical parameters of coal body, unit weight of overlying strata, dip angle of coal seam, dip angle of structural weak plane, mining depth and working face length are the main influencing factors. When the width of coal pillar a≤6.8m, the coal pillar in 4103 section will lose stability. (2) The minimum width of narrow coal pillar is 7.28m by using the theory of stable core area and 5.95m by using the theory of limit equilibrium. Combined with the actual production, the optimal width of coal pillar in 4103 working face is determined to be 7m. (3) The displacement monitoring shows that the maximum displacement of the two sides of 4103 return air roadway is 520mm, and the maximum displacement of the roof and floor is 280mm, which meets the stability requirements of the surrounding rock of the roadway. (4) 14 observation stations are arranged in the middle distance between coal pillars. The monitoring results show that the volume fraction of carbon monoxide is in the normal range in the whole process of roadway excavation, cut through and normal mining of working face, and no other gas signs are found. The results show that the coal pillar in 7m section meets the requirements of air leakage prevention in spontaneous combustion coal seam, and there is no oxidation and spontaneous combustion. The research results can be used for reference in the design of coal pillars in the working face of similar conditions.
- 1
Estimating three-dimensional JRC value of rock fracturesAbstract:
Measurement and estimation of joint roughness coefficient (JRC) is critical but also a difficult challenge in the field of rock mechanics. The measurement of JRC is especially important in the fields of mine construction, cavern excavation, disaster prevention. Previous JRC evaluation methods based on single or multiple profiles cannot fully reflect the overall roughness of the fracture surface. Based on direct shear test of rock fracture surface, with the help of three-dimensional laser scanning and modeling analysis technology, a three-dimensional evaluation method of JRC value is systematically studied. It was found that: (1) 3D parameters describing the entire roughness of fracture surface can be classification into 4 types, namely are slope parameter, area parameter, height parameter and volume parameter. (2) nine parameters (θs, θg, θ2s, SsT , SsF, Van, Zsa, Zrms and Zrange) are found to have close correlations with JRC value and are capable of estimating JRC value of rock fracture surfaces. Other parameters (Zss, Zsk, Vsvi, Vsci, Sdr and Sts) show no good correlations with JRC. (3) The sampling interval has little influence when using volume and amplitude parameters (Van, Zsa, Zrms and Zrange) for JRC estimation, while it influences to some extent when other parameters (θs, θg, θ2s, SsT and SsF ) are used. (4) For their easy calculation, the equations with amplitude parameters are recommended to engineering practice to facilitate rapid estimation of JRC value.
- 1
The study of a emergency treatment technology of drinking water when the river water burst thallium pollutionAbstract:
In July 2018, a county in Hunan province found the concentration of thallium in a river, which is the drinking water source of the county, exceeded drinking water standard, during a routine monitoring of source water quality. The Ministry of Ecology and Environment, and the local governments along the river launched emergency response plans and carried out emergency treatment. After investigating the suspected enterprises, the local ecology and environment departments took effective measures such as controlling and diluting the pollution source to reduce the water concentration. Local government of downstream adopted emergency thallium removal treatment processes, which is weak alkaline potassium permanganate pre-oxidation combined coagulation and precipitation, in the water plant. The thallium removal rate of the drinking water can reach up to 84%, when the thallium concentration in the raw water over standard within 2 times. The water quality of the water plant was stable and meets the standard requirements. The emergency thallium removal process can be combined with the conventional treatment process of water plant. It is easy to be implemented, simple to be operated, has obvious effects and low cost. It can be popularized in the water plants when the raw water burst thallium pollution.
- 1
RESEARCH ON MONITORING AND EARLY WARNING OF GANGUE FIELD BY USING EXTENSION THEORYAbstract:
Real-time monitoring and early warning of the safety status of the waste dump slope can reduce the risk of slope destruction. Using extension theory and entropy index weighting, the component methods of the gangue safety evaluation model are determined. The safety level of the slope is divided into four levels. And the safety level is correlated with the slope stability coefficient, and the section area of the six indicators of slope, displacement and groundwater is calculated. Finally, an extension evaluation model for the safety of gangue field is established. Using this model to analyze the monitoring data of the gangue field slope, the results show that under the current conditions, rainfall will only affect the safety status of the slope in a short period of time, causing the fluctuation of the safety level characteristic value. The safety level of the gangue dump in Wangjialing Coal Mine is maintained at level Ⅰ, and the slope is in a stable state.
- 1
Research on Infiltration Law and Failure Mode of Rare Earth Tailings Pile under RainfallAbstract:
Abstract：Rainfall infiltration is one of the main factors inducing the instability of rare earth tailings piles. In order to explore the rainfall infiltration laws and damage forms of rare earth tailings piles under different rainfall modes and different slope angle, 30 angle, 45 angle and 60 angle rare earth tailings pile model under different rainfall modes were used to monitor the pore pressure and water content. The results show that: (1) under the same slope angle, different rainfall mode conditions, the failure modes of the rare earth tailings piles start from the bottom and gradually evolve from shallow failure to collapse failure. (2) The damage of the tailings pile has a corresponding relationship with the rainfall intensity. The greater rainfall intensity, the more likely to be destabilized and damaged. (3) With the same rainfall mode, the greater slope angle, the faster rainfall infiltration, the shorter time for its water content and pore water pressure to reach a stable equilibrium, and the more unstable of the rare earth tailings pile, the failure mode is not only shallow and collapse, but also accompanied with sliding failure. This result can provide a theoretical reference for the collapse and landslide of rare earth tailings pile under rainfall infiltration.
- 1
Study on the technology of deep hole pre-crack pressure relief gob-side entry retaining in super long working faceAbstract:
In view of the problems such as soft and broken surrounding rocks and difficult supporting of gob-side entry in super long working face, taking the safe and efficient mining of Chensilou Coal mine 2803 as the engineering background, deep hole pre-crack pressure relief along goaf roadway was applied to improve the control effect of surrounding rocks.Through theoretical calculation, got intake airflow roadway deep hole pre-crack pressure relief the best height is 17 m, The reinforcing support scheme of intake airflow roadway along gob is designed, and the engineering practice and application effect are measured and analyzed, analysis results show that: (1) The deformation trend of the three roadway in front of the working face increases with the decrease of the distance from the working face, The deformation of the intake airflow roadway is the largest, followed by the return airway, and the middle lane is the smallest, The maximum moving amount of the two sides is 198mm, roof and floor maximum nearer to 120 mm;(2) intake airflow roadway along empty roadway section, behind the working face roadway deformation within the scope of 15 m fastest, The deformation velocity of roadway slows down in the range of 15-70m, but the deformation quantity continues to increase, 70 m later became stable gradually, two sides roadway maximum nearer to 710 mm, roof and floor maximum nearer to 295 mm, therefore, the effect of deep hole pre-cracking pressure relief along the gob-side entry retaining in 2803 super long working face is better.
- 1
Study on roadway support technology of special thick and soft coal seamAbstract:
For solving the problems of loose and easily broken surrounding rock and difficulty of supporting, 2304N roadway in Xinjulong Coal Mine is taken as the research object, Through the method of equivalent circle, the loose ring of 2304N roadway roof is 1.82 m, the loose ring of the gang is 1.42 m, and the supporting scheme of the joint support of the bolting belt mesh and cable is determined. The supporting parameters are designed based on the theory of, suspension theory and composite beam theory, and the bolt length is 2.5 m, bolt spacing is 0.9 m, bolt spacing is 1.0 m, roof anchor cable length is 8.3 m, roof angle anchor cable length is 6.3 m, anchor cable spacing is 1.8 m, anchor cable spacing is 2 m. Through FLAC3D numerical simulation, the convergence of roof and the approximation of two sides 32.4 mm 38.4 mm, respectively Based on the field monitoring, the convergence of roof and the approximation of two sides are 20.7 mm 24.1 mm respectively. The results of on-site monitoring prove that the combined support scheme of bolting belt and net cable can control the deformation convergence of the roadway in super thick soft coal seam.
- 1
Research on Mixing Proportions of Backfilling Cementitious Material through Artificial Intelligence Neural NetworkAbstract:
Cemented tailings backfill mining is more and more widely used. Due to the high content of fine particles and many active and harmful chemical components, new cementitious materials based on cement and metallurgical slag in the construction industry are not suitable for mine backfilling. In order to reduce the cost of backfilling, this paper, taking Zhongguan iron mine as an example, changes the thinking strategy, bypasses the specific hydration reaction and its influence mechanism, and adopts the artificial intelligence algorithm to study the proportioning development of mining cementitious materials as a "black box" perspective. The results show that using high temperature fast curing and artificial intelligence algorithm can shorten the proportion development cycle of cementitious materials, reduce the technical requirements, thus reducing the cost of material development. Through orthogonal experiment and artificial neural network model, the optimal cementitious materials proportion for Zhongguan iron mine is clinker 8%-9%, desulfurized gypsum 2%-3%, glauberite 0.5%, slag powder 89.5%-87.5%. Finally, the results was proved by a verification experiment, conforming the feasibility of artificial intelligence neural network in the development of backfilling cementitious material proportion, which is conducive to the sustainable development of green and low-cost metallurgical slag cementitious material in cemented tailings backfilling.
- 1
Modeling and Analysis of Round-link Chain Transmit system for Deep mining continuous HoistingAbstract:
Deep shaft ring chain continuous lift drive system has been widely used in mine industry. The structural rationality and operational reliability of the system play an important role in the safety and stability of mine operation . In this paper, according to the characteristics of the multi-point driving and continuous lifting system of deep shaft and large capacity, a THREE-DIMENSIONAL digital model is established for the key parts of the system, including the driving device, hopper and ring chain system, and the rationality of its structure is analyzed and solved by finite element method using ANSYS Workbench. The yield strength of the main shaft of the driving device, the strain and total shape variables of the hopper and the strength of the ring chain are checked and analyzed . In order to ensure the reliable operation of the system, the fatigue life of the ring chain is calculated . The equivalent stress nephogram and the minimum fatigue life curve of the ring chain are obtained . It provides theoretical support for further research of multi - point drive continuous lifting system.
- 1
Study on the cylindrical Micro-slump and Yield Stress of Paste SlurryAbstract:
Slump is an important index of paste filling slurry fluidity, which reflects the smoothness or difficulty of paste flowing in pipeline to a certain extent. The traditional ASTM standard slump cylinder needs a large number of tailings and occupies a large area, so it is suitable for on-site testing but not suitable for colleges and universities to carry out slump testing. The purpose of this study is to explore a reasonable miniature cylindrical slump cylinder suitable for paste filling. This paper establishes a mathematical model between the degree of slump and yield stress, and finds that the cylindrical slump cylinder has more advantages in the measurement of paste slump. By using self-made micro-cylindrical slump cylinders with different height-diameter ratios and standard slump cylinders to carry out slump experiments, it was found that micro-cylindrical slump cylinders can better reflect the fluidity of paste. The yield stress is calculated by mathematical model, which is consistent with the yield stress measured by rheometer. Through the comparison of linear regression accuracy and error analysis, a cylindrical slump cylinder with a height of 100 mm, a diameter of 67 mm (height-diameter ratio of 1.5:1) and a material of 0.352 L was selected to replace the standard slump cylinder for paste fluidity test, which provided a more direct and effective method for paste slump test.
- 1
Study on determination method of reasonable mechanized mining height in fully mechanized caving of thick coal seamAbstract:
In order to determine the reasonable mechanized mining height of fully mechanized top coal caving in thick coal seam, based on the finite difference and discrete element numerical calculation method, the influence of mechanized mining height on top coal failure, coal wall stability and top coal caving law is studied. The results show that: with the increase of the mining height, the advance support pressure increases first and then decreases. When the mining height is 3M, the stress peak value is the largest. At this time, the horizontal deformation degree of the coal wall and the fragmentation degree of the top coal in the roof control area are also moderate, and the caving performance of the top coal in the roof control area is the best. At the same time, the discrete element simulation results show that when the mining height is 3M, the recovery rate of the top coal in the caving process is the highest and the recovery rate of the top coal is the highest The gangue rate is the lowest, so the reasonable mining height is determined to be 3 m. on this basis, combined with the geological conditions, the reasonable selection of the main supporting equipment in the working face is carried out.
- 1
Numerical Simulation of Rock Breaking of PDC Cutter Based on Discrete Element MethodAbstract:
The study of rock breaking mechanism is of great significance for field application such as oil production drilling, coal and mineral mining, tunnel and underground cavern building. The structural parameters of cutting tools and the real physical environment have significant influence on the rock breaking effect. In this paper, the discrete element method is used to simulate the cutting rock breaking effect of PDC teeth under different cutting speeds, cutting angles, cutting depths and confining pressure parameters, and the changing law of cutting force and rock crack development is obtained. The results show that during the rock cutting process of PDC bit, the cutting force increases approximately linearly with the increase of cutting speed and cutting depth. The cutting force is the smallest when the cutting angle is 10 °. Confining pressure will significantly enhance the strength and plasticity of the rock, which will affect the rock breaking effect of PDC cutting teeth.
- 1
Selection of the Site of the Technical Renovation Project of the ConcentratorAbstract:
In order to comprehensively, scientifically and effectively determine the site of the technical renovation project of the concentrator, the site for the technical renovation project of the concentrator is numerous, and has the problems such as the use of the site is limited and the effective connection with the existing facilities. Taking the selection as an example, the research and analysis of the site selection of the molybdenum concentrator were carried out, and finally the site 1 was determined as the optimal site. By analyzing the whole practice process of this example, an efficiency method for site selection of the technical renovation project of the concentrator was summarized and summarized: the list of the sites should be complete; qualitative analysis fist and then quantitative analysis; focus on the differences, choose the best and compare the objects, and step by step to find the optimal site. The efficiency method of site selection is particularly suitable for technical renovation projects, and it has a strong reference for the concentrator and factory plant projects.
- 1
Multi-parameter Measuring Device for Electrostatic Induction Dust Based on Karman Vortex StreetAbstract:
Aiming at the problem that the existing electrostatic induction coal dust measuring device, with a single function, is not accurate in the case of low concentration and low velocity, according to the principle of Karman vortex street, it is proposed to install a slit cylindrical generator in the measurement device, to increase the movement velocity of coal dust, thereby increasing the induced charge of the electrostatic sensor and improving the measurement accuracy of coal dust concentration; At the same time, Fast Fourier Transform (FFT) is used to solve the velocity and flow information of the particles, using the periodic change of the electrostatic signal induced by the periodic change of the particle velocity in the measurement device. Then the multi-parameters of coal dust is realized. The simulation experiment results show that the parameters of the velocity (flow rate) and concentration of coal dust can be obtained, which according to the periodic change of induced charge. This method is characterized by the simple structure and a small calculation amount of sensor parameters.
- 1
Adsorption and separation of CH4 / CO2 in simulated coalbed methane with modified silica gelAbstract:
The modified silica gel adsorbent (SGA-MEA-Ba) was obtained by the alkaline-earth metal (Ba) and ethanolamine (MEA). The physical and chemical properties, regeneration performance of the modified silica gel and its separation effect of CH4 / CO2 mixture in simulated coalbed methane were analyzed. The experimental results showed that, after the modification of alkaline-earth metal (Ba) and ethanolamine .The specific surface area and total pore volume of SGA were reduced; - NH2 appeared after the modification; except for the diffraction peak of Ba element in the modified SGA, the structure of the residual phase had no special change before and after the modification. After the modification of alkaline earth-metal (Ba) and ethanolamine, the adsorption capacity of SGA for CO2 increased from 1.34mmol/g to 3.30mmol/g, and the separation efficiency for CO2 / CH4 mixture increased from 9.14 to 9.92.
- 1
STUDY ON KEY TECHNICAL OF MINE INTELLIGENT VENTILATIONAbstract:
Intelligence is in its infancy at present our country coal mine, The ventilation system is one of the important links to decide the production and safety of coal mine, this article explores the key technology to realize intelligent ventilation in coal mine, expounds the concept, architecture of intelligent ventilation, 3 d ventilation simulation system is established, analyzed the accurate acquisition system parameters, the method of air distribution method based on the minimum power consumption, air volume adjustment method based on intelligent algorithm, as well as remote intelligent control system. Field experiments were carried out on the 8272 working face of Yangdong mine of Jizhong Energy Fengfeng Group to verify the reliability of the above key technologies, which laid a solid foundation for the realization of intelligent ventilation in the mine.
- 1
Study on Ecological Restoration, Protection and Utilization Strategies of Resource-depleted Mining Areas——The Case of Lenghu Petroleum Base Site RuinsAbstract:
In the post-industrial era in which technological innovations have taken place, most industrial types of mining areas are facing the dilemma of being abandoned due to the exhaustion of resources. At the same time, as an important material and cultural carrier to witness human industrial civilization, various types of industrial and mining sites are increasingly appearing in the World Heritage List, and the attention of industrial and mining heritage is gradually increasing. As an energy-based industrial and mining heritage, the site of Lenghu Petroleum Base is located in the Yadan landform group in the Qaidam Basin, where the ecological load is extremely fragile. The problems of environmental pollution and geological disasters in the area of the site are more prominent. Ruins of the Lenghu Petroleum Base protection and utilization cannot exceed the environmental carrying capacity, on the one hand, formulate feasible governance and transformation measures, on the other hand, respect the original pattern of industrial and mining heritage, and explore the economic, cultural and scientific value.
- 1
Numerical simulation study on the failure law of soft rock roadway considering the property deterioration of surrounding rockAbstract:
In order to explore the deformation characteristics and failure forms of soft rock roadway with high stress after water degradation, based on the example of deformation engineering of auxiliary transportation roadway on the north wing of Zhaoxian mine in Shaanxi Province, following the general law of rock mechanical property degradation under the action of water rock, FLAC3D numerical simulation is adopted, and from the angles of plastic development of surrounding rock, shear stress distribution and rock movement along the depth range, etc In this paper, the deformation of surrounding rock under three conditions of slight, medium and serious rock deterioration is analyzed. Then the deformation of surrounding rock under four different horizontal stress environments (10MPa, 14MPa, 18Mpa and 22Mpa) is studied by numerical simulation. It is found that the expansion to the bottom plate and the side of the wall is an important channel for unloading of high stress soft rock after deterioration, and the roof is almost not Affected by the influence, the bad high stress environment and the deterioration of rock lithology will aggravate the deformation of surrounding rock, expand the scope of surrounding rock loose circle, and seriously endanger the active bearing capacity of surrounding rock itself.
- 1
Study on Optimization of Negative Pressure of Gas Drainage in Directional Drilling of Ultra Thick CoalAbstract:
In order to solve the problem of low gas concentration and short period of validity of gas extraction in the downhole bedding gas pre-drainage borehole of baode coal mine, the method of combining theoretical analysis, numerical simulation and field measurement is adopted to determine the negative pressure of drainage in the bedding gas pre-drainage borehole of baode coal mine. The results show that the gas concentration is 88% in the extraction period and 2.48 m3/ min in the extraction period when the negative pressure is 13KPa in the directional drilling of the 81310 return air area of Baode Mine, while the average gas concentration is 50% in the 18KPa extraction negative pressure and 1.41 m3/ min in the drainage period. The optimal extraction negative pressure for the fixed 81310 return air is 13KPa
- 1
Prediction of the strength of aeolian sand filling based on PCA-BP neural networkAbstract:
In order to measure the effect of mine filling, the BP neural network model and the PCA-BP neural network model were constructed to predict the strength of aeolian sand filling. After establishing models, six parameters of loess content, aeolian sand content, cement content, fly ash content, concentration and curing time were selected to test. After the test is completed, the simulation effect of models were evaluated from three aspects: the fitting degree of the data, the error analysis of the network and the prediction results. And the results show that the fitting degree of the BP neural network model data is high, the relative error is 14.57%, and the test results are not different. PCA-BP the fitting degree of the neural network model data is high, the relative error is 8.71%, and the prediction result is accurate and effective. moreover, comparing the two models, it is found that the PCA-BP neural network model has better training results and higher accuracy, which can replace the BP neural network model as an effective method to predict the strength of the filling body.
- 1
Study on optimization of cemented filling test with ultrafine full tailingsAbstract:
In order to solve the problems of low strength of backfill and high consumption of cementitious materials caused by cementitious filling with extremely fine total tailing, the best filling process of extremely fine total tailing was optimized by cementitious filling test of extremely fine total tailing, and the best ratio parameters were obtained. Taking a mine as an example, through the calculation and analysis of the performance evaluation of extremely fine full tailings, natural settlement test, collapse test, proportioning strength test and artesunate transportation test, and the best filling technical parameters were obtained. The results shows that the maximum natural settlement concentration of the tailings in 24 hours is 73.4%. And the natural settlement alone cannot meet the requirements of the mine dynamic settlement and continuous filling operation. The full tailings concentration is above 78%, which is difficult to realize artesian transportation. For the full tailings concentration of 74~76%, when the filling slurry flow rate is 150m3/h and the inner diameter of the pipeline is 150mm, the slurry flow rate in the pipeline is 2.36m/s, the pipeline transport resistance is 2.1~ 4.4kPa /m, and the filling doubling line of the artesian transportation can be realized as 4~11. When the total tailings concentration is 76%, the ratio of ash to sand is 1:4-1:8, and the strength of the filling test block in 60 days is 1.78-3.62 MPa, which can meet the strength requirements of the Mined-out area.
- 1
Response surface method optimizes spray conditions for nanocellulose dust suppressantsAbstract:
The spray conditions for nanocellulose dust suppressor is optimized by using the response surface method.On the basis of single-factor experiment,in order to further optimize the dust suppressor spraying conditions and study the interaction between the main influencing factors,the function relationship between the factor and the response value is analyzed by the current commonly used response surface design method.With the environmental temperature, wind speed size and dust suppressor concentration as the argument, the coal dust concentration is the response value,the central combination test of three factors is designed to study the effect of each factor and its interaction on the dust suppression effect.The results showed that the spray conditions for the optimized nanocellulose dust suppressor was 25℃ for ambient temperature,8 m/s of wind speed and 5% concentration of dust suppressor.Under this condition, the coal dust concentration reached a minimum of 1.7080 mg/m3,which is basically in line with the theoretical prediction.The interaction between ambient temperature and wind speed size is not significant,the interaction between wind speed size and dust suppressor solution concentration is not significant,and the interaction between ambient temperature and dust suppressor solution concentration is significant.This study provides a theoretical basis for the actual use of dust suppressor,which can not only effectively suppress dust and dust,but also save the use of dust suppressment to a certain extent,thus reducing costs.
- 1
Experimental Study on Acoustic Emission Characteristics of Yellow Sandstone under Freeze-ThawAbstract:
In order to study the influence of freeze-thaw on the mechanical porosity, compressive strength and acoustic emission characteristics of rock, uniaxial compression mechanics and acoustic emission experiments, with temperature range (- 20,20) ℃, were carried out on the yellow sandstone for 40 freeze-thaw cycles. The results showed that in the process of 0-15 cycles of freeze-thaw, the porosity was positively correlated with the number of cycles increasing. A single cycle of freeze-thaw increased the porosity of sandstone by 0.07-0.08%. After more than 15 cycles of freeze-thaw, the increase rate of porosity gradually decreased and tended to 0. The compressive strength of yellow sandstone is negatively correlated with the number of cycles increasing, and the compressive strength of yellow sandstone decreased by about 0.8% after a single freeze-thaw; the cumulative number of acoustic emission ringing decreased with the increase of freeze-thaw cycle, but the decreasing rate was nonlinear with the number of freeze-thaw cycles. After 20 and 40 freeze-thaw cycles, the cumulative number of acoustic emission ringing is about 50% and 70% lower than that of rocks without freeze-thaw cycles, respectively. The research results provided a reference for the calculation of strength parameters and stability analysis of slope rock mass in cold region.
- 1
Numerical Simulation Research on Coal Pillars with Different Width Protection in High Stress Thick Coal SeamAbstract:
In order to study the problem of retaining the coal pillar width in the roadway driving process of high-stress thick coal seam, according to the engineering geological profile of the driving face, the FLAC3D numerical calculation method was used to simulate different coal pillar widths, and the vertical under the coal pillars of different widths was obtained. Study the distribution law of stress, horizontal stress and plastic zone. The research results show that the coal pillar width has a great influence on the surrounding rock stress of the roadway. The peak stress reaches 43.3 MPa with a 5 m coal pillar, and the peak stress is 27.5 MPa when the coal pillar width is 25 m. During the tunnel excavation process, The compressive stress is much greater than the tensile stress. The tensile stress increases first and then decreases with the width of the coal pillar. When the width of the coal pillar is 15m, the maximum compressive stress is 20.7Mpa, and when the width of the coal pillar is 20m, the minimum compressive stress is 17.7MPa; The width of the coal pillar is less than 10m, the overall coal pillar is in a plastic state, the width of the coal pillar is greater than 10m, the width of the elastic core area increases with the width of the coal pillar; comprehensive consideration, the best width of the coal pillar for retaining roadway is 20m. The results of this study provide a reference basis for coal pillar retention under similar conditions.
- 1
EXPERIMENTAL STUDY ON STRENGTH CHARACTERISTICS OF CEMENTED BACKFILLAbstract:
Cemented backfill is widely used in filling mining, and its strength characteristics have a very important impact on mining safety. Taking the cemented backfill of Jinding Mining Industry in Shandong Province as the research object, the physical properties and strength characteristics of the tailings and three kinds of cementing materials were analyzed by routine physical tests, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and uniaxial compressive strength (UCS). On the basis, cemented backfills with four kinds of proportions, 1:3.5, 1:3.8, 1:4 and 1:6, as well as three kinds of concentrations, 54%, 52%, 50%, were designed with No. 2 cementing material as cementing material. Then UCS, SEM and XRD tests were carried out to obtain the results of static and dynamic tests with different proportions and concentrations and the microstructure of backfills. The results show that: (1) the strength of three kinds of cementing materials in Jinding Mining Industry is mainly affected by anhydrite , and has a positive correlation with the amount of added anhydrite because the anhydrite can make the cemented material hydration reaction more complete; (2) fineness of tailings and concentration of filling slurry have a significant impact on the static strength of filling materials; (3) the fibrous, needle like and radial ettringite overlapped with each other in C-S-H gel and tailings, forming a stable hydration product. However, due to the fine size of the whole tailings, the sparse distribution of aggregate, and the existence of gap, the samples had a certain low strength.
- 1
The Control Technology of High Stress Broken Surrounding Rock in Kilometer Deep WellAbstract:
In order to solve the ground control problem of high stress, broken surrounding rock in kilometer-deep hard rock mines, a new support design method was proposed. Based on the engineering geology investigation of the surrounding rock discontinuities of the deep roadway in Sanshandao Gold mine, the relationship between the direction of the maximum principal stress and the discontinuities strike of the surrounding rock of the roadway was analyzed. The stability of the surrounding rock of the roadway was analyzed by using the stability chart, and the wedge formed by the discontinuities of the surrounding rock was analyzed by using the UNWEDGE software. On this basis, the supporting scheme of the surrounding rock was proposed, and the supporting effect was calculated by RS2 software. The plastic zone and displacement of the surrounding rock are significantly reduced after supportd, it is shown that the support scheme adopted can ensure the stability of the roadway. Therefore, the comprehensive research method combining the empirical method and numerical simulation can accurately analyze the stability of the roadway and determine a more reliable support scheme. It provide a reliable guarantee for the safe production of the mine.
- 1
STUDY ON THE DAMAGE PROPERTIES OF BLASTING TO THE FILLING BODY IN THE REMOTE BLASTING AREAAbstract:
The early mechanical properties of the filling bodies possess an important role in shortening the two-step mining period.This article used macro and micro methods,Carried out simulated blasting disturbance test with self-made medium and long range blasting disturbance test device, strain test, compressive strength test and SEM scanning analysis，the mechanism of the influence of frequent blasting disturbance on the mechanical properties of early filling bodies was studied.The results of the study showed that as the ages increased, the anti-disturbance capability increased, and when no axial load was applied, the horizontal and vertical strain curves were asymmetric;after the filling bodies were disturbed by the impacts, the compressive strength decreased, and the maintenance of the disturbed filling bodies were continued, and the compressive strength was greater than that of the undisturbed filling bodies;the impact disturbances could increase the surface area of the gel bodies and improve the homogeneity, so that the unhydrated gelling material particles could react with part of the pore water and gel water released, and generated hydration products to fill the pores, reduced the porosity, made up damage, improved the strength of the disturbed filling bodies.
- 1
Evaluation of geological stability of western open-pit mining area based on improved AHP methodAbstract:
the numerous factors affecting the geological stability in the west open-pit mining area, In the geological subdivision of the west open-pit mining area by AHP method ,it is proposed to use values between 0.5 and 1.0 on the basis of the original “3 scales ” scale the importance of the two, and to establish a level 2,3 categories and 8 research area fuzzy evaluation system in the construction judgment matrix. After the weight calculated by the me was substituted in, the comprehensive engineering geological partition was obtained after the Arc Gis layers were superimposed .The comparison of the site building damage shows that the improved AHP method is more in line with the engineering practice. Finally, some suggestions on slope and building reinforcement are put forward for some unstable areas. This method can be used to evaluate the stability of the western open-pit mining area.
- 1
Progress in remediation technology of contaminated groundwater from in situ leach uranium miningAbstract:
This paper describes the principles of the natural attenuation, pump and treatment, permeable reactive barrier, chemical precipitation and microbial remediation techniques for the remediation of groundwater from in-situ leach uranium mining, points out the disadvantages of the natural attenuation, pump and treatment, permeable reactive barrier, chemical precipitation techniques including low treatment efficiency, high treatment cost and easy secondary pollution to the environment, and the advantages of the microbial remediation including less investment, quick effect and no secondary pollution, and prospects that microbial electrochemical remediation technology is the research direction and key point for the remediation of groundwater from in-situ leach uranium mining.
- 1
Study on AE Characteristics of Rock Deformation and Failure Evolution under Tension ShearAbstract:
The AE characteristics of rock under tension shear failure were studied by three-point -bending test of granite with different offset distance of pre-cracks. DSCM was used to calculate the speckle image collected by CCD camera, and the characteristic parameters of the rock AE signal collected by AE system were analyzed. The results showed that the peak load of the rock increased with the increase of the offset length of the pre-crack, there was a blank period of about 1-5s after the occurrence of the maximum ring count, before loading to the peak, the AE ring the sudden increase of the count and the value of the maximum ring meter had nothing to do with the length of the pre-crack offset; the curve of the b value before the peak value was very dense, the high and low value areas interacted with each other and fluctuated violently, this feature can be used as the precursory information of the peak value of the specimen, as the pre-crack offset length increased, the rock b value near the peak value showed a decreasing trend; as the loading progressed, the difference between the magnitude of the rock crack opening rate and the dislocation rate gradually decreased, near the peak both the opening rate and the dislocation rate decreased. With the increase of the pre-crack offset length, the ring count surge increased from the opening rate surge to the dislocation rate surge.
- 1
Experimental Study on Fine Mud Dressing ofWolframite and ScheeliteAbstract:
In order to solve the impact of the treatment of weathered ore on the flotation operation of a tungsten ore dressing plant, on the premise of unchanged main process flow, the new asynchronous separation process of“ore washing-fine mud concentration-scheelite flotation-tailing magnetic separation-shaker cleaning selection”was developed, the output of scheelite coarse concentrate enters the original process selection process, the flotation tailings are pre-selected by high gradient magnetic separator, and the shaker selection produces wolframite concentrate mine. The test result showes that when the ore grade is 0.96%WO3, the grade of scheelite concentrate is 5.04%, and the recovery is 71.80%; the grade of wolframite concentrate is 52.41%, the recovery is 20.86%, and the comprehensive recovery is 92.66%.
- 1
NUMERICAL SIMULATION OF STRESS EVOLUTION AND SURROUNDING ROCK CONTROL TECHNOLOGY IN DEEP BROKEN ROADWAYAbstract:
In order to solve the problem of supporting the deep broken surrounding rock roadway of a metal mine, the numerical simulation of the reinforcement effect of different supporting schemes under the condition of instability and failure of surrounding rock roadway is carried out by FLAC3D. The deformation law of surrounding rock under unsupported、anchor bolt support、bolting and shotcreting support、bolting and shotcreting +cable bolt support is analyzed. The results show that under different support conditions, the vertical stress of roadway surrounding rock forms a le type" stress concentration area at about 2m~5m away from the roadway side. The horizontal stress of roadway surrounding rock presents an asymmetric "butterfly" distribution. The maximum displacement of roof and floor can be reduced by 50%, 60% and 80% respectively by anchor bolt、bolting and shotcreting、bolting and shotcreting +cable bolt support. In the process of roadway excavation, the law of surrounding rock deformation is: two sides > roof > floor. However, the floor heave phenomenon of roadway is still serious even after the two sides and roof are supported, it is suggested to adopt concrete hardening treatment.
- 1
The Investigation of Uniaxial Creep Characteristics and Constitutive Equation of Sandy Mudstone under the Thermal-Mechanical Coupling EffectsAbstract:
To investigate the stability of underground engineering under deep conditions, the uniaxial high temperature creep testing apparatus was adopted to conduct the creep experiment of the sandy mudstone under the conditions of constant stress and four different temperatures (25°C, 50°C, 100°C, 150°C) over 100 days and the thermal effect on the creep parameters was introduced to build the improved Burgers model. The results showed that the sandy mudstone under the low temperature presented the obvious viscosity characteristics of solids, but it gradually presented the character of a viscous fluid with the increase of temperature, which caused the more obvious creep behavior. As the temperature increased, the time of transient creep stage grew, and the creep strain rate of steady creep stage increased by the exponential function over time. Also, the creep strain increments of mudstone under the condition of 50°C, 100°C, 150°C are 163%, 175% and 1125% of that under the condition of 25°C, respectively. At 25°C, creep strain rate of sandy mudstone at the steady creep state is 4.23e-6/d, and it increased to 5.34e-6/d at 50°C, 1.16e-5/d at 100°C, 3.96e-5/d at 150°C, respectively, which are 1.26 times, 2.47 times, 9.36 times of that at 25°C,respectively. The improved Burgers model well described the creep characteristics of sandy mudstone under high temperatures, and Young’s modulus E1 decreased linearly with increasing the temperature, but Young’s modulus E2 and viscosity coefficient η1、η2 decreased non-linearly with the increase of temperature.
- 1
Study on the effect of supercritical CO2 on the degradation of coal mechanical propertiesAbstract:
Supercritical CO2 can cause the change of mechanical properties while enhancing the exploitation of coalbed methane. Based on this, the effects of supercritical CO2 temperature and action time on the mechanical properties of anthracite coal are studied in this paper. The results show that: (1) with the prolongation of soaking time, the peak strength of uniaxial compression stress-strain curve of coal sample decreases and the peak change is not significant; with the increase of soaking temperature, the elastic characteristics of curve is obvious, and the curve changes from no obvious peak to peak value (2) Both soaking time and soaking temperature can affect the mechanical index of coal. When the soaking time is less than 1 day, the decrease of elastic modulus and compressive strength of coal is obvious, and then the decrease gradually tends to be gentle; with the increase of soaking temperature, the elastic modulus and compressive strength of coal sample increase slowly. (3) The effect of supercritical CO2 soaking time on the mechanical properties of coal is more significant than that of soaking temperature. (4) With the increase of soaking time, the deformation failure mode of coal sample transits from tension shear failure to shear failure, and the instability mode changes from sudden instability to quasi sudden instability. With the increase of soaking temperature, the fracture form of coal sample changes from shear fracture to tension shear fracture, and the instability form changes from quasi sudden instability to progressive failure, and finally to sudden instability.
- 1
Study on the Influence of Lead-Zinc Mineral Processing Wastewater on Lead Sulfide FlotationAbstract:
For the problem that lead-zinc mineral processing wastewater has an adverse effect on lead sulfide flotation, the study analyzed the main components of the wastewater and the main reasons affecting the flotation of lead sulfide ore and revealed the mechanism of the mineral processing wastewater affecting lead sulfide ore flotation. The lead-zinc mineral processing wastewater has the characteristics of variety of metal ions, high content of suspended solids, high COD, and high pH. The effects of pH and various ion contents on the floatability of lead sulfide ore were investigated. The results showed that calcium ions had a greater effect on lead sulfide ore. The high concentration of calcium ions in the mineral processing wastewater is mainly due to large quantitiesSofSlime used as an inhibitor during lead-zinc ore flotation process. The main reason why calcium ions change the floatability of lead sulfide minerals is to affect the adsorption of collectors on the mineral surface. The study provides references for realizing the reuse of mineral processing wastewater and improving the utilization rate of water resources.
- 1
The response characteristic of horizontal pillar to stoping sequence in high stress environmentAbstract:
With the normalization of efficient exploitation of deep resources, a series of safety problems caused by high stress environment have become prominent, posing great challenges to efficient mining. Aiming at the safety problems in the simultaneous mining process of deep multi-level and multi-oreroom mining model, this paper expounds the crush mechanism of the stoping sequence from the optimization of the reasonable stoping sequence. Through the numerical simulation experiment, the original view of horizontal pillar was observed, and the characteristics of horizontal pillar stability response to mining sequence were analyzed, thus the stability control scheme of horizontal ore pillar was put forward. The results show that the stoping sequence has a great influence on the stability of horizontal pillar. For simultaneous stoping, the maximum principal stress in the horizontal pillar increases rapidly, which is easy to induce destructive instability. The maximum principal stress under the condition of sequential stoping is lower compared with simultaneous stoping, since there is a process of slow adjustment and transfer. Taking one every the other one scheme ensures the simultaneous construction of multiple zones and reduces the effect of high stress concentration, providing a favorable environment for safe and efficient stoping of deep resources, and the maximum principal stress only increases 2% than sequential stoping.
- 1
Study on the improvement of mining method of inclined medium thick ore body in Xingou Scheelite MineAbstract:
It is very difficult to solve the problem of ore transportation in stope when mining inclined medium thick ore body. According to the specific situation of Xingou scheelite mine, the traditional sublevel caving mining method without sill pillar is improved and studied. By caving a small amount of footwall surrounding rock, the dip angle of ore drawing is increased properly to ensure the smooth ore drawing. The research results show that the scheme saves a lot of mining and cutting projects, reduces the direct mining cost by 32 yuan / T, achieves good economic benefits, improves the safety of operation, provides a good idea for the efficient and safe mining of similar ore bodies, and has a good prospect of promotion.
- 1
The influence of slope on dust movement and settlement in spiral tunnelAbstract:
Taking the Midi village spiral tunnel as the engineering background, full-size 3D spiral tunnel models with slopes of 2%, 4%, 6%, 8% and 10% were established and numerical simulation was carried out by FLUENT software"s discrete phase model, so as to study the influence of slope in spiral tunnel on dust migration and deposition rules. The simulation results showed that there was a power function relationship between the dust concentration in the spiral tunnel and the distance from the tunnel face, and the power exponent of this relationship and the slope in the upper and lower spiral directions was further fitted. When the spiral is applied, the slope increases and the power index increases, which is conducive to the diffusion of dust in the tunnel. During the downward spiral construction, with the slope increasing, the power index increased, which is conducive to dust diffusion in the tunnel. During the upper spiral construction, with the slope increasing, the power index decreased, which accelerates the dust deposition. By the above relations, the dust distribution in the construction spiral tunnel with different slopes could be understood, and also could provide a reliable basis for guiding the dust removal work..
- 1
Internationalization Strategy and Implementation Plan of Large State-owned Fertilizer Enterprise GroupAbstract:
Under the background of “Belt and Road” and domestic supply-side reform, the fertilizer manufacturing industry has started a major shift from resource intensive to technology intensive. Therefore, only by conducting international and strategic management and seeking rich development resources can the fertilizer enterprise gain a broader market, enhance the sustainability of development and occupy a place in global competition. In the present study, a systematic research had been done on the internationalization strategy and implementation plan of large state-owned enterprise group by the literature analytic method and case method. The disadvantages of enterprises were analyzed. The quality and services of products to serve consumers through technological innovation, marketing and multi-channel strategy etc. were improved. By increasing the international influence, building its own brands, and innovating the mechanism of talent introduction, a diversified product system is formed. Key products are highlighted. Comparative advantage in the market is achieved.
- 1
Support Optimization of the Drilling Chamber and Ore Revomal Drift in Deep Mining StopeAbstract:
Due to the mining depth of Zijinshan Au-Cu mine reached 800m. And the large-diameter longhole sublevel sublevel open stoping with delayed filling method was used in two-step stoping by ore room and pillar. During the mining, roof fall and rib spalling in both the drilling chamber and ore revomal drift occurred, the support were invalid and damaged to different degrees, which led to a significant increase in the support cost. Through the site test of original ground stress, the characteristics of original ground stress in the mine area were summarized. Then the rock mass quality was evaluated by the classification methods of RQD, RMR and Q system. And the safety factor of the potential unstable block was calculated with UNWEDGE three-dimensional wedge stability analysis software. And the influence of different support parameters on the stability of the drilling chamber and ore revomal drift was analyzed. As a result, the support scheme and parameters were optimized and the measures of the layout and support method in the drilling chamber and ore revomal drift were studied systematically. The field application effect is good, which guarantees the safety and efficiency of mining.
- 1
The Effect of Freeze-thaw Cycles on the evaluation method of rock mass qualityAbstract:
The physico-mechanical properties of the red sandstone under the?freezing and thawing?condition taken from Tibet Yulong copper mine is studied. The mass, longitudinal wave velocity, elastic modulus, uniaxial compressive strength, stress-strain curve and the micro-change characteristics of rock samples were analyzed after different freezing-thawing times. The decay function model is used to calculate the decay constant and half-life of red sandstone, and it analyzed the freeze-thaw integrity loss of red sandstone. Change tendency of the opencast mining slope rock mass quality after freeze-thaw damage was studied combining with the RMR rock mass quality evaluation system. The results showed that the surface of rock gradually exfoliates as the freezing-thawing process progresses. The decay function model is suitable for the strength attenuation of freeze-thaw rock on the slope of opencast mining. The freeze-thaw decay constant of red sandstone is 0.04335 and its half-life is 16 times. After the first five freeze-thaw, the rock mass quality levels of red sandstone slope changes from good rock（Ⅱ）to medium quality（Ⅲ）, and RMR values gradually reduce and tend to be gently from 5 to 50 times of freeze-thaw, but they still are medium quality (Ⅲ) rock mass. This research based on freeze-thaw test and freeze-thaw damaged rock mass quality evaluation method of decay function model, can provide help for the modification of mechanical parameters of engineering rock mass and the engineering transformation of freeze-thaw test results.
- 1
Coupling support technology and application of broken strong plastic rock roadwayAbstract:
As the main engineering structure of the mine, roadway support has become the main problem that perplexes the economic and efficient development of the mine. With the continuous increase of mining depth and intensity, the complex geological conditions such as strong disturbance and weak broken surrounding rock will lead to deformation and destruction of surrounding rock, roof caving, floor heave and other phenomena, which will seriously affect the ventilation and transportation capacity of the roadway and restrict the safe and efficient production of the mine. Therefore, it is very important to carry out the research on the coupling support technology of the broken rock roadway, effectively control the deformation of the surrounding rock and realize the stability in the service period of the roadway. In view of the complex engineering conditions such as the development of rock joints and fissures, strong plasticity and so on in Taiping iron mine, Anhui Province, the deformation monitoring of the roadways in each middle section of the mining area is carried out, and the characteristics of the deformation and failure of the roadways are analyzed. The FLAC3D finite element software is used to simulate the interaction of the roadways under different time and space conditions, forming the structure of prestressed anchor rod, steel wire mesh, shotcrete, grouting, pressure relief groove, etc Coupled support mode, and then carry out the field support test of the mine roadway, the surrounding of the roadway did not appear expansion, fracture and other damage phenomenon, the roadway repair rate is very low, the overall support effect of the roadway is good, which provides technical support for the safe and economic mining of the mine.
- 1
Analysis of Delamination and Separation Phenomenon of Filling Body and Optimization of Filling Process in a Copper MineAbstract:
the designed annual production capacity of a copper mine is 300000 tons. The open stope and subsequent filling mining method is adopted, and the filling slurry enters into the stope and then the separation occurs. Based on the analysis of the existing technological process of the copper mine, the main reasons for the delamination and segregation of the filling slurry in the stope are as follows: due to the poor thickening effect of the horizontal sand basin, the concentration of the discharged sand is too low and the continuous filling time is too short, resulting in the low preparation concentration of the filling slurry, which is diluted by the approach water and washing water after entering the stope, and the concentration is further reduced.Through the optimization of the existing filling process, the preparation concentration of the filling slurry is increased to 74%,and the continuous operation of the filling system is ensured for more than 18 hours, which greatly improves the single filling capacity of the filling system and greatly reduces the impact of the approach water and the washing water on the filling concentration. By increasing the preparation and transportation concentration of the filling slurry and extending the continuous filling time, the separation phenomenon of the filling slurry is effectively reduced, which provides a good reference for the control of the separation phenomenon of the filling slurry in domestic mines.
- 1
Experimental Study on Improving Beneficiation Indicators of Dry Concentration in A Dressing PlantAbstract:
In the view of insufficient processing capacity and magnetic agglomeration problems in the dry preconcentration of the fine crushing products in a dressing plant in Inner Mongolia. The magnetic separator was structurally improved by the idea of wind-gravity-magnetic separation. The change of mineral dressing indexes were investigated after the air was fed by using the experimental prototype. The results showed that, with the increase of wind speed, the formation of vortex and the turbulence of particles have a more significant effect on the depolymerizing with feed TFe grade of 13.51% and mFe grade of 3.98% and feed size of -4mm. The concentrate assaying mFe grade of 31.03% with recovery of 82.71% was obtained and the tailing with mFe grade of 0.77% and high yield of 89.48% were discarded when the rotating speed of 130r/min, wind speed of 25m/s and the material thickness of 30mm. Compared with the index of windless, the mFe grade of preconcentrate can be increased by 4.01% and the mFe grade of discarding waste rock was reduced by 0.32%. The index of dry magnetic separation has been significantly improved in the dressing plant.
- 1
Grouting Control Technology and Engineering Application of Strong Dynamic Tunnel of Mine CurtainAbstract:
Mine curtain is an effective technology for groundwater treatment in large water mines in China, and the effective sealing of karst strong moving water channel directly determines the water blocking effect of curtain Engineering, even the success or failure. Based on the curtain Engineering of the fifth section of Fankou Lead zinc mine, the characteristics of the karst channel to be injected and the flow velocity of groundwater are found out by means of tracer test and densified drilling. Through the groundwater dynamics and seepage theory, the parameter equation of aggregate under the state of groundwater movement is obtained to calculate the amount of aggregate put in. Finally, a four-step dynamic water grouting scheme of injecting aggregate, injecting rapid setting expansion material, double liquid slurry and finally strengthening with ordinary cement slurry is adopted to block the strong dynamic water channel with a water flow of 6000 m3 / D at one time. The curtain water blocking rate has been increased from 67% to 75%, saving 6.9816 million yuan of water and electricity cost per year. This technology can be used for reference in the construction of strong dynamic water grouting in similar curtain Engineering.
- 1
Comprehensive Evaluation of Ecological Risk of Heavy Metal Pollution in Coal Mines in Arid Areas—Taking Zhundong Hongshaquan Coal Mine as an ExampleAbstract:
The exploitation of coal resources induces the pollution of heavy metals in the soil of arid and fragile ecological environment. In this paper, the content of Cr, Cu, Zn and Hg in 50 sampling points of Zhundong open pit coal mine and its surrounding areas were determined. The soil heavy metal pollution status of the sample points was comprehensively evaluated by using the geological accumulation index method, the potential ecological harm index method, the enrichment index method and the transfer coefficient method. The results showed that the contents of Cr, Zn and Hg in the soil in the study area were all higher than the background values in Zhundong area. There was a certain correlation between Cr, Cu and Zn, and the accumulation of heavy metals in the soil was related to the production activities in the mining area. The geological accumulation index in the mining area and in the area of Jiji lake reached 4.81 and 3.38, showing moderate pollution. The index intensity of potential ecological hazard was as follows: the mining area was larger than the Jiji lake than the Queren town than the Jiangjun temple. The concentration index of Reaumuria Linn to Cu in the mining area is 1.07, and the concentration index of Reaumuria Linn to Hg in Jiji lake area is 4.4, which indicates that Reaumuria Linn has enrichment and transport effect on heavy metals in soil. The content of heavy metals in soil is distributed along the road direction, which is related to the density of coal mining and transportation . The content of the four heavy metals in the section of Jiangjun temple road, which is not the main transportation road, is lower than that in the center of Jiji lake and the mining area where traffic flow is concentrated.
- 1
Experimental Research on Beneficiation Process of a Lead-Zinc Sulfide Ore in Sichuan ProvinceAbstract:
In view of the problems of fine distribution granularity of galena and Sphalerite in a polymetallic lead zinc sulfide mine in Sichuan, and low separation efficiency of lead and zinc in the beneficiation site. The technological process of "preferential lead separation - lead coarse concentrate regrinding and selecting - lead tail zinc separation . The experimental results show that under the condition of grinding fineness of - 0.074mm and the content is 75% , zinc sulfate as inhibitor、25#aerofloat as collector. Through the one-coarse-three-fine-two-scan experiment process, a lead concentrate containing 45.58% Pb、5.43% Zn and 861.72g/t Ag,with 84.11% Pb、6.00%Zn and 81.84% Ag recovered are obtained. The tailings of the lead tailings are adjusted by lime, copper sulfate is used as activator, butyl xanthate is used as collector, through the one-coarse-three-fine-two-scan experiment process, a Zinc concentrate containing 54.10% Zn and 87.14% Zn recovered are obtained. The experimental results are good, which not only solves the problem of low separation efficiency of lead and zinc, but also provides some reference for the comprehensive recovery of other similar complex polymetallic minerals.
- 1
Research on Mechanical Properties and Durability of Acetylene Slag Activated Ultra-fine Iron Tailings Cement MortarAbstract:
Aiming at the solid waste resource of low-activity iron talings, acetylene slag as weak alkaline excitation and supplemented by wet grinding, the mechanical properties and durability of cement mortar composite material of acetylene slag-ultra-fine iron tailings system was studied. tests showed that the median diameter can reach 0.89μm by 120min wet grinding, and both ultra-fine and excitation by acetylene can improve the mechanical properties and durability of composite material system, under the condition of 30% iron tailings dosage, 3d and 28d compressive strength of acetylene slag-ultra-fine iron tailings system up to 17.2MPa and 42.1MPa. The chloride permeability of composite system might cause a decline when the dosage exceed 30%, although the carbonation resistance was not as good as blank sample, it could meet the basic durability requirements.
- 1
NUMERICAL EXPERIMENTAL ON THE WHOLE PROCESS OF BRITTLE AND PLASTIC FRACTURE OF ROCK SAMPLESAbstract:
In order to explore the relationship between the shape of rock samples and their plastic properties, numerical model of medium particle marble and the Three Gorges granite was established in PFC2D , and the uniaxial compression test of numerical specimens with different aspect ratios were carried out. Comparing the stress-strain curves, it could be seen that as the aspect ratio decreases, both lithological samples show a trend from brittle failure to ductile failure. At the same time, the acoustic emission mode were transformed from the main-post shock type to front-main-post shock and group shock type. In addition, the brittleness index of different aspect ratio specimens was calculated with two common brittleness evaluation methods. With the change of aspect ratio, the brittle and plastic properties of rock showed great difference, and the brittleness index of the specimen was positively correlated with its aspect ratio. According to the changes of stress-strain curve, acoustic emission curve and brittleness index, the characteristics of brittle-ductile-plastic transformation of rock specimens with the change of aspect ratio were better described.The essence of brittle and plastic failure of rock lies in the way of fracture propagation. Brittle instability of rock is caused by one or fewer main fractures penetrating through, while plastic instability always produces more main fractures.
- 1
Rapid development method and application of shaft ramp in deep inclined thick orebodyAbstract:
For the deep inclined thick ore body, the conventional vertical shaft development circular transportation system leads to a long time of new horizontal development, due to the large development work quantity of stage circular transportation. With the increase of the production capacity of the stope, the falling speed of the working face increases, which resulted in the shortening of the mining time in the stage. Therefore, the preparation time of the development system restricts the high-intensity mining. Based on practical experience, the current situation of xiaowanggou iron mine of Xigang Dengta mining company analyzed in paper for solving this problem, After the combination of main lifting and trackless transportation in stope, the method of shaft lifting and ramp opening was adopted. the stage development project was greatly reduced, the contradiction that the development progress cannot keep up with the mining requirements was solved. At the same time, the qualified block size of the stope was increased from 0.75m to 1.5m by truck transportation, so the ore-drawing capacity of scraper was increased by more than 80%. In addition, the original design of single car passing form was changed to double car passing form, and the transportation capacity was increased by more than 80% in the ramp transportation line. Generally, the rapid development method of shaft ramp in Xiaowanggou iron mine is advantageous for not only safe, reliable, low cost of skip shaft lifting, and flexible and fast ramp section opening, but also the high production capacity of the mine, which can ensure the safe and high-intensity mining of the deposit.
- 1
Analysis and Discussion on the disintegration mechanism of consolidated body of tailings under the condition of immersionAbstract:
According to the disintegration characteristics of the consolidated body of the whole tailings, the disintegration characteristics of the consolidated body of the whole tailings under different cement content are studied through the water immersion disintegration test, and the disintegration mechanism of the consolidated body of the whole tailings is discussed. The results show that with the increase of the cement content, the disintegration resistance of the specimen is improved significantly. When the cement content is more than 2%, the consolidated body will not disintegrate and muddy when encountering water. After the whole tailing consolidated body is immersed in water, the matrix suction causes the water infiltration to remove the gas between the pores with connectivity, which causes the skeleton with weak connection to be destroyed during the gas discharge process; with the water infiltration of the tailing consolidated body, the saturation of the consolidated body increases, the matrix suction decreases, and the surface tension decreases. The decrease of the surface tension reduces the bond force between the solid particles, and the solid skeleton breaks down under the disturbance and extrusion of the gas.
- 1
Study on high-efficiency recovery of ultra-lean fluorite with high content of calcite in ChongqingAbstract:
The content of fluorite and mineral composition of the fluorite ore in Chongqing vary greatly. Some has low grade of fluorite and high content of fine-grained calcite. The fluorite concentrate containing CaF2 of 83% with recovery of 56% is obtained by the existing mineral processing flowsheet. By using high-efficiency calcite depressant and selective collector, the grade of fluorite concentrate reaches 97.05% and the recovery rate reaches 77.99% and the grade of barite concentrate reaches 93.57% and the recovery rate reaches 73.58%.The problem that the type of fluorite cannot be used efficiently is solved and the economic benefit is significant.
- 1
Study on the influence of paste filling mining on the floor failure lawAbstract:
In view of the water inrush from the bottom of the coal seam, it is easy to be induced,In this paper, the engineering background is 6351 working face in 3 upper coal seam and 8300 belt roadway in 3 lower coal seam. By means of numerical simulation test and "comparative analysis", the movement rule of surrounding rock and the influence of filling rate on the failure depth of the floor are studied under the mining conditions of caving method and paste filling method. The simulation results are as follows: in the gypsum filling mining, the failure of surrounding rock is mainly shear and tensile failure, and the failure depth of the floor under the conditions of gypsum filling and caving mining is 4m and 18m respectively; The stress nephogram shows a symmetrical "Butterfly" distribution, and the peak value of the stress in paste filling and caving mining is 12.83mpa and 36.97mpa；The research results show that paste filling mining can greatly reduce the depth of floor damage and effectively reduce the probability of floor water inrush,Increasing the filling rate can effectively reduce the crack expansion of the floor; the field measurement shows that the floor of the 6351 filling working face of 3 upper coal seam can be roughly divided into the upper failure area, the middle complete rock zone and the lower plastic area, with the maximum failure depth of 3.802m.The relevant research can be the preparation for the next step of mine safety and efficient recovery of coal seam above confined water.
- 1
Experimental Study on Flocculation Settlement and Denseness of Ultrafine Red Mud PasteAbstract:
The flocculation settlement of red mud is a key technology in the preparation of bauxite paste filling slurry, which is of great significance to the normal production of mining enterprises. In order to explore the flocculation and settlement rule of red mud under different conditions, the flocculation and settlement experiment of red mud was carried out by taking the red mud produced by an aluminum oxide plant in Shanxi Province as an example. Origin software was used to draw the flocculation and settlement velocity curve and bottom flow concentration curve of red mud, and the characteristic parameter values suitable for the flocculation and settlement of red mud and the process parameters of deep cone thickening machine were optimized. The results show that the red mud settlement curves show a trend of rapid rise, then decline and finally reach the level, and the final dynamic bottom-flow concentration is higher than the static bottom-flow concentration . Under the optimal conditions, red mud is suitable for flocculant of HP20 category, the concentration of red mud slurry should be 15%-16% , the optimal unit consumption of flocculant is 35g/t, and the concentration of deep cone bottom flow is recommended to be 48-50%.The results can provide theoretical basis for the study of flocculation sedimentation at home and abroad.
- 1
Study on Dynamic Parameters and Dissipative Energy of Increasing-unloading Red Sandstone at Different FrequencyAbstract:
The cyclic loading and unloading tests of saturated red sandstone under different frequency and different dynamic stress coefficients are carried out on the RMT-150b rock mechanics test machine. The dynamic elastic modulus, damping ratios, damping coefficients and hysteresis of red sandstone in the increasing and decreasing stages are discussed. In the increasing stage, the dynamic elastic modulus increases parabolically with the increase of the dynamic stress coefficient, and in the decreasing phase, the dynamic elastic modulus increases linearly with the increase of the dynamic stress coefficient; The damping ratio decreases parabolically with the increase of the dynamic stress coefficient, and increases power function with frequency; The damping coefficient decreases power function with the increase of the dynamic stress coefficient, and increases parabolically with frequency; The maximum width of the dynamic stress-strain hysteresis loop increases linearly with the increase of the dynamic stress coefficient in the increasing stage, and shows a parabolic increasing in the decreasing stage. The maximum width of the hysteresis loop increases logarithmically with the increase of frequency; There is a linear function of the product of the maximum width and amplitude of the hysteresis loop and the area of the hysteresis loop law; The dynamic elastic modulus, damping ratio, damping coefficient, and maximum hysteresis loop width of the increasing stage at the same frequency and the same amplitude are larger than the decreasing stage.
- 1
Study of Fracture Propagation Law of Hydraulic Fracturing in Hard Roof of Tashan Coal MineAbstract:
The hydraulic fracturing technology can be used to weaken the hard roof of the coal seam. In this paper, based on the extended finite element method of the ABAQUS, a numerical simulation of the crack propagation of the roof K3 sandstone in Tashan Coal Mine was carried out, and the fracture morphology under the different principal stress differences, injection rate, liquid viscosity, elastic modulus and fracture spacing were analyzed. The simulation results show that the principal stress differences, injection rate , elastic modulus and fracture spacing have a significant effect on the fracture parameters, and the viscosity has no obvious effect; the larger injection rate, elastic modulus and the smaller principal stress difference can cause the increase of the fracture initiation pressure; the larger injection rate and viscosity, smaller principal stress difference and elastic modulus, can cause the increase of maximum fracture width; larger injection rate, principal stress difference and elastic modulus can cause the increase of expansion radius; as the fracture spacing increases, the subsequent fracture is less disturbed, and this can cause the increase of expansion radius. The study results provide the propagation law of the hydraulic fracturing fractures of the hard roof, and provide a certain reference for the design and construction of hydraulic fracturing in Tashan Coal Mine.
- 1
Influence of deep mining under multilayer goaf on the stability of shaftAbstract:
In order to study the influence of deep mining under multilayer goaf on the stability of shaft. Taking a gold mine in Inner Mongolia as the engineering background, and the dynamic mining process of the mine was simulated by the numerical simulation method and the measured rock mechanics parameters. The displacement rules, stress distribution and plastic zone distribution characteristics of the shaft surrounding rock were obtained. The results show that with the mining of the deep ore body, the deformation of the shaft increases obviously, especially in its lower part. The maximum and minimum principal stresses of the surrounding rock in the goaf increase with the mining of the deep ore body, but the surrounding rock near the shaft is still in the original rock stress state. In addition, the volume of the plastic zone increases with the mining of the deep ore body. Therefore, it is necessary to disposal the goaf in time to ensure the safety production of the mine.
- 1
Prediction for blasting fragmentation of rocks using random forest and GA-BP neural networkAbstract:
In order to better predict the blasting fragmentation, the blasting fragmentation statistics data of multiple mines in the world are divided into two groups based on the modulus of elasticity, and a random forest discriminant model and a GA-BP neural network prediction model are established. The ratio of spacing to burden, ratio of bench height to drilled burden, ratio of burden to hole diameter, ratio of stemming to burden, powder factor, in situ block size and modulus of elasticity is taken as input parameters, and the blasting fragmentation is predicted. The results show that the correlation coefficient (R^2), root mean square error (RMSE), and mean relative error (MRE) of the prediction results are better than the multiple regression prediction model and BP neural network prediction model, and better than the GA-BP neural network prediction model established without grouping, which is more suitable for the practical application of blasting operation, and provides a new idea for the prediction of blasting fragmentation under the influence of multiple factors.
- 1
Study on The Stability of Goaf Based on The Coupling Action of Complex Goaf and Pillar in Many LevelsAbstract:
In order to study the stability of goaf under the coupling action of complex goaf and pillar in multiple middle sections, based on the research background of Ji"an mining goaf, the numerical simulation MIDAS-GTS/NX and FLAC3D coupling calculation method is used to study the stability of underground goaf. The results show that the maximum vertical displacement of each middle section is less than 3cm after mining. The maximum vertical displacement occurs in the middle of the roof and floor of the goaf. The displacement of roof and floor is directly proportional to the deformation of surrounding rock and the scale of goaf. The tensile stress is mainly distributed in the roof and floor of the goaf, and the compressive stress is distributed in the pillar between the goafs. The overall tensile stress of surrounding rock in goaf is small, and there is a phenomenon of tensile stress concentration in some parts. The plastic area is mainly distributed near the excavation space, and the plastic units are all distributed in the surrounding rock within 10m from the goaf. The main failure mode of plastic zone is tensile failure. Controlling the mining scale and reducing the size of the stope are conducive to improving the overall stability of the goaf. The research results can provide reference for mine safety production.
- 1
The stimulus response of chitosan and its flocculation effect on fine tungsten tailingsAbstract:
The effect of chitosan on the flocculation behavior of tungsten tailings has been studied and the mechanism has been discussed. The sedimentation results show that pH did not influence the settling behavior of tungsten tailings particles and the sedimentation velocity is slow at the studied pH. Chitosan is a useful flocculant for the settling of tungsten tailings but the flocculation effect of chitosan is influenced greatly by pH. When chitosan was added at pH 9,large floccules can form and the sedimentation velocity of tungsten tailings is more quickly. The reason is that chitosan has a critical solution pH above which it become insoluble and strongly adsorbs onto the particles surfaces. The adsorbed reagent molecules are interconnection and make the particle form large floc, which accelerate the sedimentation process. When the pH was decreased from 9 to 3, the adsorbed chitosan dissolved from tungsten tailings surface and the flocculation effect disappeared. The flocs were disorganized to the particles and the sediment consolidated to significantly higher densities.
- 1
Research of Mechanical Properties and Failure Modes of Sandy Mudstonewith Grouting FracturesAbstract:
Uniaxial compression tests are conducted by using MTS815 electro-hydraulic servo control test machine for the rock-like specimens with filling fractures in order to investigate the effects of grouting on the mechanical properties and failure modes.The stress-strain curves,mechanical parameters and failure modes of each type of specimens are analyzed in detail based on the experimental results.Conclusions are drawn as follows:①Grouting filling can change the shape of stress-strain curve.For the filling specimens, the phenomenon of step down of the post-peak failure stage is alleviated,thus makes the phenomenon of solw decline in horizontal extension no longer exists.②The mechanical parameters such as peak strength,elastic modulus and peak strain can be significantly improved by grouting filling with maximum averge degree of 36.76%,11.41% and 12.71%.③The effect of fracture angle on the mechanical properties of specimens decreases as the angle increases. Besides,the filling results gets better with the decline of fracture number.④Fracture angle has a great effect on the failure modes of single or double fracture specimens; The failure modes can be changed by fracture number under the conditon of 0°fracture angle, with the increase of the fracture number,the specimens gradually changed from main shear failure to main tensile failure,however,there is no specific transformation rule under the conditon of 45°and 90°fracture angle.⑤The failure mode is more simlar to complete specimens when the fracture angle is to 0° or 90°;The smaller the fracture angle is,the greater the friction and cohensive of the fracture face,and the closer the failure mode of fracture specimen is to the complete specimen.
- 1
Analysis of the Concrete Speed Reduction and Mixing Efficiency of the Sleeve-connected Buffer in Deep ShaftAbstract:
In order to improve the speed reduction and mixing efficiency of the sleeve-connected buffer, optimize its structural parameters and solve the problem of concrete segregation. Orthogonal test method was used to design the plan, and the width, height and base length were used as variables to build buffer models with different structural parameters. EDEM software was used to calculate the movement of concrete slurry at the exit of the buffer with different structural parameters under the same blanking conditions. Using the outlet speed and relative speed of the slurry as indicators, the speed reduction and mixing efficiency of different retarders were analyzed. Through the range and variance analysis to determine the degree of parameter influence on the indicator, and determine the best combination of structural parameters. The results show that the primary and secondary order that affects the exit speed of the descender is width> height> length. When the width is W2, the speed is the smallest. As the length increases, the slurry speed increases. The parameter affecting the relative speed is the width, which gradually decreases as the width increases. Within the selected range, the sleeve-connected buffer with the structural parameter of W2H1L2 has the best performance, and the slurry outlet speed and relative speed are reduced by 7.41% and 64.23% respectively. The research results provide theoretical support for the safe transportation of wells in deep vertical shafts.
- 1
Application analysis of the stage large-diameter deep hole open stope and subsequent filling mining method in huangshan south copper nickel mineAbstract:
Abstract：In order to solve the problems of poor technical and economic indexes, high mining loss and dilution rate and high lump rate in Huangshan south copper nickel mine, and to improve the production and operation of the enterprise, combined with the mining technical conditions of the ore body of the mine, the stage large-diameter deep hole open stope and subsequent filling mining method was adopted for application research, and preliminary success was achieved. At the same time, the application practice shows that the mining method has the advantages of safety, low dilution loss rate and high comprehensive economic benefits, the production capacity of the stope can reach 400~600t/d, it can realize the purpose of centralized and efficient mining operation, ensure the production capacity of the mine continuously and stably, and obtain better economic benefits,and it has been widely popularized application prospect.
- 1
Experimental Study on Filling Application of High Mud Content TailingsAbstract:
In view of the technical problems of filling and utilization of high mud content tailings.The tests of filling materials of full tailings and graded tailings were carried out.The test parameters include:tailings settlement，mechanical dehydration performance，Slurry fluidity，Initial and final setting time，Filling strength Etc.Combined with the requirements of filling mining technology ,the utilization plan of tailings is determined by comprehensive evaluation and analysis.The test results of total tailings show the high-quality filling slurry cannot be prepared; the initial and final setting time of the filling slurry is long, the strength performance of the filling body is poo,which can not fully meet the requirements of mining technology.Through grading measures to remove part of ultra-fine particles and grading tailings test, the filling slurry has good fluidity, the strength performance has been greatly improved, which can fully meet the requirements of mining technology. Therefore, it is recommended to use graded tailings as filling aggregate.The graded tailings filling system is established. The practice proves that the graded tailings filling can meet the requirements of mining technology.
- 1
-
2016,36(1):1-4, DOI:
Abstract:
-
2016,36(1):5-9, DOI:
Abstract:
-
Wang Cheng, Sun Baosheng, Zhang Jian, Gao Mingxing
2006(2):81-82,85, DOI:
Abstract:
This paper analyzes the problems existing in the production safety in China's mines.The authors consider that the three main aspects influencing the production safety of China's mines are production environment,techniques and equipments,production management,and suggest countermeasures to utilize advanced scientific technology and establish a perfect and high-effective safety management mechanism in order to strengthen the production safe of China's mines.
-
Li Qiang, Wan Liangbiao, Liu Zhende
2008(5), DOI:
Abstract:
针对中金岭南公司统计工作的难点,以及原有统计软件单机运行、集成性差、工作效率不高的状况,结合多元化经营的实际情况和精细化管理的要求,提出并设计开发了基于网络的中金岭南统计工作新平台,从技术上和流程上为企业统计工作实现精细化管理提供了有力支持。
-
2002(6):1-3,59, DOI:
Abstract:
生产矿山的配矿环节受多种条件的制约，作者在考虑各种配矿受限条件的基础上，用混合型整数线性目标规划方法研究了用于露放和地下矿编制短期生产配矿计划的数学模型，并论述了数学模型的解算方法。
-
Wang XifuZhang YoudiZhang Daxian
1999(4):8-11, DOI:
Abstract:
Because semicontinuous process system has many links, the coordination of links and the types of equipments in the system have greatly influences on its production capacity. This paper mainly makes research on the coordination of links and mode selection of equipments in mines semicontinuous process system, So that the operational efficiency and total productive capacity of this system can be increased.
-
2008(5), DOI:
Abstract:
巷道工程的稳定是矿山生产的关键,巷道的变形破坏制约着矿山的生产,特别在高应力破碎软岩矿区,这一问题尤为严重。针对金川矿区的复杂地质构造条件,对影响巷道工程稳定的客观因素(地应力、地质构造、地下水、岩体时间流变效应等)和人为因素(开采扰动、爆破、巷道空间布置、支护方式等)进行了综合分析,提出了巷道优化布置和支护的合理建议,为矿山进行合理的巷道工程设计和施工提供科学依据。
-
Zhou Wei, Bai Zhongke, Yuan Chun, Yuan Tao, Qian Mingjie
2008(5), DOI:
Abstract:
地形是区域自然环境的重要组成部分,数字地形分析为人们研究地表演化过程提供了全新的技术支持。基于1∶10000比例尺DEM数据,在数字地形分析的基础上,对平朔露天煤矿区原始地貌和人工堆垫地貌的高程-平面面积、高程-地表面积和地表水系结构进行了对比研究。结果表明,人工堆垫地貌较原始地貌高度增加20~100 m;面积随着高程变化而变化,相同高程情况下人工堆垫地貌的表面积要比原始地貌大。人工堆垫地貌较原始地貌的面积在海拔1475,1425和1350 m处变化幅度大;矿区地貌景观特征发生了巨大的变化,人工堆垫地貌呈塬面水平梯田形,顶上平坦,坡面为凸形;人工堆垫过程引起原始地貌地表水系的自相似性遭破坏,人工堆垫地貌出现了环形和放射状水系,现代水系格局尚未定型。
-
2008(5), DOI:
Abstract:
From the background,manners and effect,this paper makes a comparison on the mineral resources development and utilization between foreign undeveloped regions and western China,and illustrates the enlightenment of foreign experiences to mineral resources development and utilization in western China.
-
Deng Ming, Zhang Guoshu, Qin Ruxiang
2008(5), DOI:
Abstract:
针对"U"型通风工作面采空区上隅角容易积聚瓦斯,以渗流理论为基础,根据气体扩散定律和质量守恒定律,建立了顶板走向钻孔抽放采空区瓦斯流场模型。在Visual-Basic6.0平台上,利用工程软件SURFER模拟了抽放钻孔周围瓦斯压力场。结果表明,煤体自身所具备的条件和抽放瓦斯的技术条件是影响瓦斯抽放量的主要因素,采取诸多因素相结合的切实可行方案,顶板走向钻孔抽放采空区瓦斯可以取得良好的效果,在技术上是可行的。
-
2000(6):1-2, DOI:
Abstract:
Starting from the concept of safety exploiting depth,the authors analyzed the relationship between safety exploiting depth,mined thickne ss and the critical deformation of structures,thus obtaining a proper method fo r the determination of safety exploiting depth,which plays an important role in d etermining whether some protective measures should be adopted for underground mi ning and surface structures.
-
Chen Ye, Chen Jianhua, Qin Hua
2008(1):32-34, DOI:
Abstract:
A series of experimental studies were made on the effect of amide collectors with different length of carbon-chain on flotation behaviors of hemimorphite,quartz,dolomite and limonite.Meanwhile,the effect of the carbon-chain length on collecting ability of amine had been discussed.The results showed that when pH value of solution is between 9 and 11,there was the best recovery of hemimorphite,the selectivity of amine to hemimorphite is increasing with the increase of the carbon-chain length,octadecylamine has better selectivity and collecting ability to hemimorphite.
-
ZHANG Zhi-cheng, XIAO Zheng-xue
2000(6):37-40, DOI:
Abstract:
The authors classified the fracture-controlled methods f or rock mass blasting,summarised and analysed the fracture-controlled meachnism of the common methods,discussed the parameters for fracture-controlled b lasting and their application effect.They pointed out that the devel opment prospect of fracture-controlled blasting in rock mass is extensive.
-
2002(6):4-6,15, DOI:
Abstract:
根据金翅岭金矿4号矿体的开采技术条件，首先初选4种采矿方法，通过技术经济综合比较淘汰劣势明显的方法，对其它方法，应用模糊数学方法，量化影响采矿法选择的指标，建立模糊评判矩阵，最后选择出最佳的采矿方法为下向人工假顶中央天井分层进路空场法。
-
2000(6):8-10, DOI:
Abstract:
In the exploitation of underground residual pillars at T onglushan Mine,some noval and unique mining techniques such as advance cutting ,sequential slice-caving and bench-pushing forward etc. were used to solve the p roblem of technique and economy unification satisfactorily in the process of re sidual pillars recovery.Some good technical effect and obvious economic benefit were achieved.This technology is possessed of better referential value and wide application prospect.
-
2008(5), DOI:
Abstract:
矿区生态系统健康预测模型是矿区生态系统健康评价理论的重要组成部分,是实现矿区生态系统健康管理的有效途径。结合矿区复合生态系统的特点,建立了研究矿区生态系统健康灰色预测模型,并对研究矿区进行了预测。结果表明:研究矿区的生态系统健康状况呈下降趋势,应加强矿区生态系统的管理和调控,以促使其向良好的方向发展。
-
Yang Lu, Gao Yongguang, Hu Zhenqi
2008(5), DOI:
Abstract:
叶绿素浓度往往是植物营养胁迫、光合作用能力和植被发育阶段的良好指示剂。对不同程度铜胁迫下玉米的"红边"变化规律的研究表明:随着铜胁迫程度的不断加深,"红边"波长位置有规律地沿着波长轴不断向蓝光方向移动;叶绿素浓度与其"红边"波长位置之间有着极强的线性相关关系。在分析的基础上,建立了基于"红边"波长位置的叶绿素浓度回归模型,其复相关系数(R2)达到0.884为植被受重金属污染时开展高光谱遥感监测研究打下了坚实的基础。
Volume 45,2025 Issue 8
安全与环保
矿物加工与资源利用
User Login
Sweep code subscribe
Governing Body：Changsha Institute of Mining Research Co., Ltd
Organizer：Changsha Institute of Mining Research Co., Ltd; Nonferrous Metals Society of China
Editor in chief：CHU Hongtao
Inauguration：1981
ISSN： 1005-2763
CN： 43-1215/TD
Frequency：12issues/y
Domestic postal code：42-176
Telephone：0731-88670962;0731-88671578
Email：kyyk81@263.net
- Most Influential Paper
