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Volume 46,2026 Issue 4
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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."
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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。
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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.
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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 46,2026 Issue 4
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Effects of Mix Proportion and Combination Parameters on the Synergistic Load-Bearing Behavior of Strong–Weak Composite Backfills
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To investigate the synergistic load-bearing behavior of composite backfills composed of strong and weak media in two-step backfill stoping, laboratory uniaxial compression tests, acoustic emission monitoring, and theoretical analysis were carried out to examine the effects of the strong–weak medium proportion and the cement-to-tailings ratio of the weak medium on the mechanical properties of the composite backfill. In addition, numerical simulations of a representative two-step stoping operation were conducted to evaluate the stope load-bearing characteristics under five combination schemes with ore-block width ratios ranging from 2:3 to 3:2. The results indicate that the overall mechanical performance of the composite backfill is jointly controlled by the proportion of the strong and weak media and their mechanical contrast. As the proportion of the weak medium increases, the overall compressive strength and elastic modulus of the composite backfill decrease in accordance with quadratic polynomial and exponential relationships, respectively. During failure, damage accumulation is more pronounced within the strong medium, with cumulative acoustic emission ringing counts 16.9%~56.0% higher than those of the weak medium, whereas surface cracks are more concentrated in the weak medium. Owing to specimen preparation effects and interfacial interactions, the measured compressive strength and elastic modulus of the composite backfill are 2.8%~14.8% and 11.1%~26.3% lower, respectively, than the theoretical predictions derived from the stress–strain relationships of the strong and weak media. Provided that the load-bearing capacity of the first-step backfill is ensured, increasing the width proportion of the second-step ore block results in a more uniform stress distribution within the first-step backfill, while roof displacement and the extent of the plastic zone do not increase significantly. Therefore, a moderate increase in the second-step mining width can reduce binder consumption by 20%~30% while maintaining overall stope stability.
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Inversion Analysis and Engineering Application of 3D In-situ Stress Field in Deep-buried Bedded Phosphate Mine
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To accurately reveal the distribution law of the initial in-situ stress field in deep-buried layered phosphate deposits and provide a basis for deep mining engineering design and surrounding rock control, a multivariate regression numerical method was adopted to conduct three-dimensional inversion of the in-situ stress field. Based on detailed geological data, a refined three-dimensional model containing faults and stratigraphic interfaces was constructed, and four basic stress conditions were set, including self-weight stress, horizontal extrusion in the X and Y directions, and shear stress in the XY plane. The inversion calculation was performed combined with hydro-fracturing measured data from 7 boreholes. The results show that the goodness of fit R2 between the inverted values and the measured values is 0.96, indicating reliable accuracy; the mining area is a high in-situ stress region, and the in-situ stress field follows the distribution pattern of σH >σ V >σ h; the maximum principal stress at the -300~-600 m level ranges from 44 to 48 MPa, with its dominant direction being N40°W~N60°W, and differences exist in the north-south direction of the mining area affected by faults; the principal stress of the shaft surrounding rock increases approximately linearly with burial depth, accompanied by local fluctuations due to the stiffness difference of rock strata. The research findings can provide a theoretical basis and technical support for the accurate characterization of in-situ stress in deep-buried layered phosphate deposits, the optimal layout of deep roadways, and the design of surrounding rock support.
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Mechanical behaviors and energy dissipation characteristics of early damaged cemented gangue backfill under uniaxial reloading
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Due to the low early strength of cemented gangue backfill (CGB), it is easily damaged and cracked under load. To study the mechanical behaviors and energy dissipation characteristics of early damaged CGB during reloading, specimens cured for 7 d were subjected to uniaxial compression damage tests under six different stress ratios, followed by mechanical performance tests and energy dissipation analysis at 28 d. Ultrasonic and acoustic emission characteristics were monitored simultaneously during the tests. The results show that when the early stress ratio exceeds 70%, the compressive strength and elastic modulus decrease linearly with increasing stress ratio, and the specimens mainly exhibit splitting failure during reloading. The lateral deformation increases with the increase in early stress ratio, and Poisson's ratio increases exponentially. During reloading, the energy consumption increases nonlinearly with strain, and the energy corresponding to the peak stress point shows a quadratic relationship with the early stress ratio. The CGB subjected to an early stress ratio of 70% has a relatively large energy storage limit. After early damage, the ultrasonic wave velocity increases rapidly with curing age, and the quiet period of acoustic emission ringing for specimens with high stress ratios is shortened during reloading. The damage process can be regarded as the fracture process of hinged keys in the structural model, and the interfacial transition zone is the weak region where damage and failure are prone to initiate. Early loading promotes the improvement of self-healing ability.
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Evolution Mechanism and Quantitative Instability Risk Assessment of Multi-layer Sliding in the High-Steep Northwest Slope of Buzhaoba Open-Pit Mine
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The northwest slope of Buzhaoba Open-pit Mine is controlled by regional tectonics and a special stratigraphic configuration, forming an inverted geological characteristic of "old rocks overlying new strata," which constitutes a significant safety hazard. This study comprehensively integrates multi-source monitoring data and numerical simulation methods to systematically analyze the deformation characteristics, evolution mechanism, and control strategies. Monitoring results indicate that the deformation mass displays a tongue-shaped geometry, with a main sliding direction of 120°, a volume of approximately 655,000 m3, and a characteristic multi-stage evolution process. Deep-seated multi-layer sliding features are identified at depths of 14-25 m and 25-55 m. Since September 2024, the surface displacement rate has exhibited a marked acceleration, with the corrected tangent angle peaking at 71° to 80°, indicative of a transition into the initial-to-medium acceleration deformation stage. Numerical analyses reveal a compound landslide mechanism dominated by a middle-layer sliding zone, currently existing in a critical state of partial slip surface coalescence. Stability assessments indicate that the factors of safety (FoS) under natural conditions are 1.010 (Profile 2-2) and 1.027 (Profile 3-3), respectively, approaching the limit equilibrium threshold. Under rainfall conditions, these values decrease sharply to 0.970 and 0.993, precipitating a surge in instability probability. Hydrological conditions constitute the key sensitivity factor; specifically, the lithological combination of overlying gravelly soil and underlying claystone forms a stagnant water zone during precipitation. This zone reduces stability through dual mechanisms: mechanical parameter weakening and the water cushion effect. Instability simulation predicts a maximum runout distance of 215 m, directly threatening mine traffic and production infrastructure. Engineering remediation measures successfully reestablished the mechanical equilibrium of the slope, reducing the tangent angle to below 49° and effecting a regime shift from incipient structural failure to a state of controlled rainfall coupled response. Drawing upon these findings, a comprehensive set of mitigation strategies is proposed, encompassing toe buttressing and reinforcement, excavation of the upper perched aquifer layer, implementation of a three dimensional drainage network, and the deployment of a tiered monitoring and early warning system. This investigation furnishes a robust scientific foundation for the stability evaluation and disaster mitigation of analogous high and steep slopes developed in overturned strata.
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Quantitative-Semi-quantitative Method (QSM)for Brine Pump Selection in Luobei Depression Based on Single-multilayered- well Pumping Test
Abstract:
Aiming at the deficiencies in the current brine pump selection in Luobei Depression Mining Area （(LDMA)）, systematic research work is carried out. Firstly, based on multilayered-well flow theory and method to system of nonlinear equations, two approaches of accurate numerical solution and optimal solution are proposed for the system of equation for hydraulic conductivity. The optimal solution approach can not only overcome the risk of convergence which may be encountered by the accurate numerical solution while solving system of nonlinear equations under abnormal data, but also fully utilize much more test data, which enhances the generalizability of single-well pumping tests in inverting hydraulic conductivity of multi-layer aquifers and becomes the base for prediction of well yield with high-precision. Secondly, by combining multilayered well flow theory and the working principle of brine pumps, the significant influence of designed dynamic water level buried depth on the two key parameters (well water yield and head) for the brine pump selection is analyzed deeply., upon which the optimum designed dynamic water level buried depth in introduced, and then a quantitative-semi-quantitative method (QSM) for brine pump selection is set up. Finally, the reliability of QSM is verified by a project case, which demonstrates that the optical solution can not only ensure the inversion of the hydraulic conductivity of respective aquafer, but also the relative error between the well yield computed by it and the measured is within 1%, whose accuracy is high enough. Based on the Q~dw curve predicted by the well yield under various design water level buried depth in 5-meter increments, the optimum designed dynamic water level buried depth for Well 4-00m1 during the next 5 years is determined to be approximately 45 meters, and the pump type determined by the above is well consistent with the experiences of LDMA. This research further improves the single- multilayered-well pumping test technology under the complex hydrogeological conditions of LDMA, and enhances the accuracy of well yield forecasting, the scientificity and rationality of brine pump selection, which has guiding significance for production of LDMA.
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Annual variability of Antimony concentration and Driving Factors from 2021 to 2025 in Groundwater, Xikuangshan mining area
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Machine learning models combined with multivariate statistical analysis were utilized to analyze the annual variability, key driving factors and future prediction of antimony (Sb) concentration in groundwater, Xikuangshan mining areas, from 2021 to 2025.The results indicated that the average value of Sb concentrations gradually decreased from 2021 to 2025. TDS and SO42- were identified as the most crucial driving factors by interpretable machine learning models, which were mainly regulated by carbonate precipitation, cation exchange, and the dissolution of sulfur-containing minerals. The SVM - Linear model was verified to possess good fitting ability and generalization performance for the prediction of Sb concentration. The research provides a scientific basis for analyzing the novel mechanism of Sb pollution and selecting monitoring indicators in groundwater.
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An Intelligent Auxiliary Decision-Making Method and System for Mine Backfill Schemes Driven by Case Data and Physical Models
Abstract:
Intelligent backfill mining is of great significance for total resource recovery, ecological environment protection, and safety guarantee. However, the current scheme design of mine backfill faces problems such as reliance on manual experience and high design costs. Furthermore, existing intelligent systems lack source decision-making capabilities. To address these issues, an intelligent auxiliary decision-making method and system for mine backfill schemes driven by case data and knowledge reasoning are proposed, aiming to achieve intelligent optimization of core design parameters such as backfill methods, material compositions, slurry ratios, and backfill strength indices. Through literature research and on-site collection, 312 mine backfill cases nationwide (including 160 coal mine cases and 152 metal mine cases) were collated to establish a standardized case database covering geological conditions, technical parameters, and material ratios. By integrating Case-Based Reasoning (CBR) and the Analytic Hierarchy Process (AHP), a multi-factor similarity calculation model was constructed. Subsequently, a visual decision-making platform with front-end and back-end separation was developed. Based on the leave-one-out cross-validation of the full case database and four real mines, internal and external dual verifications of the system's decision-making accuracy were carried out. The results show that the matching accuracy of the backfill method for the Top 1 preferred scheme generated by the system reaches 91.67%, and the engineering compliance rate is 93.59%, with the scheme generation taking only about 1.35 s. For external independent mines, the recommended backfill methods are completely consistent with the actual applications, and the relative errors of core indicators are all less than 7%, which falls within the allowable engineering error range (≤10%). The system can effectively replace traditional manual trial-and-error design, lower the design threshold and material costs, and provide reliable auxiliary decision support for mine engineering and technical personnel.
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Real-time Monitoring and Application of Wire Rope Stress in Mine Hoisting Systems Based on Computer Vision and Deep Learning
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The complexity of the geological conditions in mines is one of the key factors restricting the safe operation of the mine hoisting system. Different geological structures will directly lead to significant differences in the vibration characteristics of the hoisting system, the force state of the steel wire rope, and the service environment. To address the issues of low accuracy, poor real-time performance and weak anti-interference ability in the stress monitoring of steel wire ropes in complex mining geological scenarios, a real-time steel wire rope stress monitoring model integrating computer vision and deep learning was proposed. This model first employs a combination of median filtering and adaptive histogram equalization with restricted contrast to suppress interference such as dust caused by mine geology, vibration noise, etc. Then, it precisely extracts the three-dimensional deformation features of the steel wire rope through semi-global stereo matching technology, and combines the Sobel operator to enhance the edge features of the stress concentration areas. Finally, it embeds a convolution block attention module to optimize the YOLOv8 network to achieve steel wire rope stress monitoring. Laboratory test results show that the accuracy rate of stress detection of the research model is as high as 96.12%, mAP@0.5 is 95.78%, the deformation positioning error is only 0.8 pixels, the stress value detection error is as low as 1.39%, the effective monitoring frame rate and average inference time are 43.6 FPS and 17.8 ms respectively, and the GPU memory usage is as low as 3.03GB. The on-site field testing and verification results show that the research model demonstrates excellent robustness in complex geological scenarios. The rate of accuracy degradation in low-light environments is 2.96%, the rate of deformation positioning error change under dust obstruction is 6.41%, and the coverage rate of stress deformation areas is as high as 98.62%. The research model can adapt to various mining geological conditions and significantly improve the accuracy and real-time performance of steel wire rope stress monitoring, providing intelligent technical support for the safe operation of mine hoisting systems.
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Multi-objective Dynamic Optimization of Underground Backfill Scheduling under Multi-source Disturbances
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In response to multi-source disturbances in underground mine backfilling systems, including fluctuations in cement–sand ratio, variations in pumping station loads, and changes in pipeline resistance, which lead to increased energy consumption, scheduling delays, and reduced transport stability, a study on backfill scheduling optimization is conducted to enhance disturbance resistance and operational efficiency. A multi-objective uncertainty-aware scheduling model oriented toward coordinated optimization of energy consumption and scheduling responsiveness is established, with objectives of minimizing unit energy consumption cost, scheduling delay time, and system stability deviation. An improved DJR-NSGA-III algorithm is developed by integrating a disturbance-aware reference point jumping mechanism and a direction vector correction strategy to overcome local optima and uneven solution distribution. Using a lead-zinc mine filling system as a case study, 1,000 disturbance scenarios were generated via Monte Carlo simulation, followed by multi-algorithm comparative analysis. Results demonstrate that without additional hardware interventions, the optimized solution reduced scheduling delays from 73.6 hours to 48.7 hours (33.8% reduction), lowered unit energy consumption costs by 6.8%, decreased system stability deviations from 9.13% to 5.14% (43.7% reduction), while improving task completion rate. Moreover, the Pareto solution set exhibits clear boundaries and uniform distribution. The results indicate that the proposed method can effectively improve scheduling efficiency and operational stability under multi-source disturbances, providing a reference for multi-objective dynamic optimization in complex conditions.
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Study on fracture propagation behavior of composite directional fracturing with pre crack and control holes in hard roofs
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To achieve directional propagation of hydraulic fractures in coal seam roofs, a composite guided fracturing technique integrating pre-cracks and control holes is proposed to direct fracture growth and reduce fracture initiation and propagation pressures. Based on linear elastic fracture mechanics theory, a mechanical model for composite guided hydraulic fracturing incorporating a borehole, pre-cracks, and control holes was established. The effects of lateral stress coefficient, pre-crack angle, pre-crack length, spacing between the pre-crack and the control hole, and control hole water pressure on fracture initiation and propagation were analyzed, and the theoretical results were verified using RFPA2D-Flow numerical simulation. The results show that the fracture initiation pressure is directly proportional to the lateral stress coefficient, pre-crack angle, and spacing, and inversely proportional to pre-crack length and control hole water pressure. The fracture initiation angle is positively correlated with the lateral stress coefficient and pre-crack length, and exhibits a trend of first increasing and then decreasing with increasing pre-crack angle. The final fracture trajectory deflection angle is directly proportional to the lateral stress coefficient, pre-crack angle, and spacing, and inversely proportional to pre-crack length and control hole water pressure. The numerical results for fracture initiation pressure, initiation angle, and propagation behavior are consistent with theoretical predictions, confirming the validity of the composite pre-crack and control hole guided fracturing model and the feasibility of the guiding fracturing method.
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Controlling Factors and Evolution Process of Landslides in Dump Sites with a Loess Foundation
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Taking the South External Dump of the Antaibao Open-Pit Coal Mine as the research object, this study systematically analyzes the controlling factors and evolutionary process of a dump slope landslide through engineering geological investigation, laboratory testing, numerical simulation, and landslide process reconstruction. The results indicate that seasonal rise of the groundwater table is the primary factor inducing instability of the dump. When the groundwater level rises from 50 m below the ground surface to 5 m, the safety factor decreases from 1.723 to 1.056. The high water content of loess reduces the strength of the foundation layer. Concentrated rainfall infiltration during the rainy season, together with drainage blockage caused by freezing at the slope toe in winter, leads to a rapid rise in groundwater level, resulting in a significant increase in the water content of the basal loess and clay interlayers and consequent attenuation of shear strength. When the water content of loess increases from 15% to 25%, cohesion decreases from 109 kPa to 41.5 kPa, representing a reduction of more than 60%. As the dumping height increases, the load on the foundation continuously rises, leading to structural damage and strength degradation of the loess. When the dumping load exceeds the structural strength limit of the foundation (78.4 m), a potential sliding surface is likely to develop and trigger overall instability, whereas the actual dumping height reached 135 m. The landslide process exhibits a typical progressive development pattern: in the early stage, compaction of the foundation and development of weak layers occur; in the middle stage, the potential sliding surface gradually penetrates; in the late stage, failure of the lower sliding mass triggers successive sliding of the upper masses, ultimately forming a large-scale circular landslide developing along the foundation. The results demonstrate that groundwater level rise, deterioration of the mechanical properties of loess, and high dumping load are the key controlling factors of the landslide. The findings provide a scientific basis and technical support for the safe operation and hazard prevention of similar open-pit mine dumps dominated by shallow loess cover.
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Study on the Overburden Movement Law under Different Spatial Structures in Underground Mining
Abstract:
During large-scale underground mining, the mining structure and sequence are complex and variable, making the study of the overburden movement patterns a challenge. In order to reveal the influence of different excavation structures and provide a reference for similar engineering problems, it takes multi-layer mining in a metal mine as the engineering background. By changing the relative positions of two mining layers, four typical mining structures were designed: overlapping structure, inclusive structure, staggered structure with ore pillars, and staggered structure. The mining processes under different structures and sequences were simulated successively using similarity model experiments and 3DEC numerical simulations, to analyze the displacement evolution patterns of the overlying rock during mining. Experimental results showed that the symmetrical structure caused basically symmetrical arch-shaped shear fractures at both ends of the mining area, while the staggered structure produced asymmetrical failure patterns. Simulation results revealed that, under different mining structures and sequences, the surface subsidence curves all exhibit a ‘U?shape’ characterized by small values on both sides and a sharp increase in the middle. After the extraction of the upper layer, the roof in the mining area undergoes a displacement of approximately 2.0 m which propagates toward the surface through the overlying strata, resulting in a surface displacement of only about 0.1?m. The extraction of the lower layer reactivates the disturbed zone in the overburden, leading to a substantial increase in the overall displacement of the overlying strata. The roof displacement is about 3.7 times greater than that induced by the extraction of the upper and middle sections.
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Study on Combined Treatment and Stability of Multi-layer Goafs in a Deep Vanadium-Iron Mine
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In view of the problems of concentrated distribution, strong spatial connectivity, and significant influence on the safe mining of the overlying vanadium ore body in multi-layer goaf groups of a deep vanadium-iron mine, a combined treatment scheme of sealing isolation and waste rock–paste backfilling was proposed based on the analysis of goaf distribution characteristics and mining influence relationships. A three-dimensional numerical model was established using FLAC3D to comparatively analyze the deformation of surrounding rock and the evolution of stress under unfilled and backfilled conditions. The results show that, under the unfilled condition, the maximum vertical displacement at the stope floor reached 25.4 mm, and the maximum shear stress of the pillar reached 11.5 MPa, indicating a local risk of shear instability. After combined backfilling was adopted, the maximum displacement at the stope floor decreased to 11 mm, representing a reduction of approximately 56%, while the maximum shear stress of the pillar decreased to 7 MPa, representing a reduction of approximately 39%. In addition, roof subsidence and horizontal displacement were effectively controlled. Field application shows that roof subsidence and pillar displacement were both effectively controlled after the combined treatment was implemented. Considering the seepage requirement of paste, the volume fraction of waste rock filling should exceed 80%. In field application, the unit cost of the waste rock–paste combined treatment was 42.43 yuan/m3, which was significantly lower than the unit cost of comprehensive cemented backfilling, 81.62 yuan/m3, and the treatment cost was reduced by approximately 48.0%. The results indicate that the combined treatment of sealing isolation and waste rock–paste backfilling can significantly improve goaf stability and has good economic applicability, which can provide a reference for the treatment of similar multi-layer goafs in deep metal mines.
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Simulation and Experimental Study on Rock Breaking by PDC Tooth Rotary Cutting
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To address the issues of cutting tooth wear and failure caused by high temperatures during drilling operations involving polycrystalline diamond compact (PDC) bits, this paper investigates the rock-cutting behaviour of PDC teeth under rotational conditions. The study employs a comprehensive approach combining theoretical analysis, numerical simulation, and field testing to construct a three-dimensional simulation model for analyzing the rotational rock-cutting behavior of PDC teeth under thermo-mechanical coupling; Focusing on the cutting edge as the core research object, the study adopted a ‘point, line, and plane’ analytical approach to examine the effects of tooth rake angle, drilling pressure, and rotational speed on the thermal behavior and mechanical response during the rock-cutting process, and discussed the thermo-mechanical coupling effects under rotational cutting conditions; finally, field rock-cutting tests were conducted. The results indicate that increasing the tooth rake angle from 8° to 12° reduced the peak cutting edge temperature from 59.60 °C to 39.80 °C, a decrease of 33.22%, and that the reaction force exhibited the smallest fluctuation at a 10° rake angle; when the drilling pressure increased from 0.5 kN to 1.5 kN, the temperature rose from 37.90 °C to 73.00 °C, representing a 92.61% increase, and the peak reaction force rose from 2.53 kN to 5.12 kN; simultaneously, at a drilling pressure of 1.0 kN, the peak reaction force during the cutting process was moderate and the curve was stable; As the rotational speed increased from 200 r/min to 400 r/min, the temperature initially decreased and then increased, dropping to 46.90 °C at 300 r/min, at which point the cutting process was most stable. The study further revealed that the thermomechanical coupling process exhibits a dynamic cycle of ‘heat generation, heat conduction, mechanical response, and thermal feedback’ with these factors mutually influencing and constraining one another, thereby affecting the stability of the cutting process and rock-breaking efficiency. Comparative rock-breaking tests demonstrated that the optimized PDC drill bit design significantly improved failure and wear issues, enhancing construction efficiency. The research findings provide a solid basis for addressing high-temperature failure issues in PDC drill bits and optimising parameter design.
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Mechanical Properties and Coupled Erosion Damage Mechanism of Silicon-manganese slag-based Filling Materials Based on Talbot Gradation
Abstract:
To optimize the ratio of solid waste-based filling materials and reveal its performance evolution law under sulfate-dry-wet cycle, based on Talbot grading theory, silicomanganese slag was used as coarse aggregate, and blast furnace slag, fly ash and desulfurization gypsum were used to prepare cementitious materials. The effects of cement-sand ratio, slurry concentration, water glass modulus and Talbot grading coefficient on slurry fluidity and mechanical properties of backfill were studied. Combined with sulfate-dry-wet cycle accelerated erosion test and scanning electron microscope, the durability degradation characteristics and microscopic mechanism were analyzed. The results show that the increase of cement-sand ratio and slurry concentration can reduce the fluidity of slurry, but it is beneficial to improve the compressive strength of backfill. The influence of water glass modulus and Talbot gradation coefficient on compressive strength increases first and then decreases. When the water glass modulus is 1.6 and the Talbot gradation coefficient is 0.5, the comprehensive performance is the best. In the early stage of composite erosion, sulfate excitation and pore filling promoted the formation of cementitious products, the structure of backfill tended to be dense, and the compressive strength increased. With the increase of erosion time, the coupling effect of crystallization expansion, dry-wet stress and sulfate erosion leads to micro-crack propagation, deterioration of cementitious products and interface damage, and the quality and strength of backfill continue to decay. The research results can provide a theoretical basis for the ratio design and durability evaluation of industrial solid waste based filling materials.
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中图分类号:TD313 文献标识码:A
Abstract:
The excavation of deep underground engineering passes through the layered rock mass, in which the excavation of surrounding rock with weak interlayer is prone to major engineering disasters such as deformation and slip failure. path. The sandstone-mudstone-sandy mudstone ( SY-NY-SN ) composite layered rock mass was used to explore the influence of confining pressure unloading on the surrounding rock with weak interlayer. The layered samples with weak interlayer ( LNY ) thickness of 1 cm, 2 cm, 3 cm and 4 cm were prepared. The conventional triaxial loading and conventional triaxial unloading confining pressure tests were carried out under confining pressures of 10 MPa, 15 MPa and 20 MPa. The peak strength, failure mode and energy evolution of samples with different weak interlayer thickness during confining pressure unloading were analyzed. The results show that : under confining pressure unloading, when the thickness of the weak interlayer of the LSY-LNY-LSN sample increases, the residual confining pressure of the peak strength is higher, and the failure changes from tensile-shear mixing to tensile failure. With the increase of the thickness of the weak interlayer ( 1-4 cm ), the cumulative event count of acoustic emission increases by 301.5 %, 191.6 %, and 139.4 % under 10,15, and 20 MPa confining pressures, respectively. During the unloading process, the failure of the sample is dominated by circumferential deformation. The axial strain variation under low confining pressure ( 10 MPa ) is 16.3 % of the circumferential, and 10 % under high confining pressure ( 20 MPa ). The strength fitting of triaxial loading and unloading confining pressure tests shows that the unloading path confining pressure has a greater impact ( 31.3 % ) when H = 1 cm, and the loading path has a greater impact ( 20.2 % ) when H = 4 cm.
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Experimental study on the effect of unloading rate on shear-seepage coupling characteristics of saw-tooth structural plane
Abstract:
In order to study the shear-seepage coupling characteristics of saw-tooth structural plane under unloading conditions, shear-seepage coupling tests were carried out on the original rock cut joints with undulation angle of 15° under normal stress of 20MPa, seepage water pressure of 0.9 MPa and four unloading rates. The effects of unloading rate on the mechanical and seepage characteristics of joints during shear process were systematically analyzed. The unloading rate is negatively correlated with permeability and flow rate, and the evolution of flow rate and permeability presents a three-stage rule. There is correlation between multi-parameters of structural plane, the damage coefficient is negatively correlated with unloading amount and maximum permeability, and the unloading amount is positively correlated with maximum permeability.At engineering level, the faster the excavation rate of rock mass, the stronger the instability, so it is necessary to strengthen risk prevention and seepage control under unloading conditions.
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Process Mineralogy Research and Comparison of Flotation Schemes for Copper Ore with High Oxidation Rate from Africa
Abstract:
Based on multiple factors such as ore properties, industrial supporting facilities, and copper concentrate utilization plan, four different processing of flotation schemes were conducted to the copper mine with complex dissemination and high oxidation rate in Africa. The results showed that both the sulphide and oxide phases of different flotation processes have been effectively recovered. The "direct sulphidizing flotation process" has lower investment and production operating costs, with a concentrate grade of 36.45% and a higher recovery rate of 83.75%, making it suitable for products to be sold locally with a low proportion of freight costs. The "direct sulphidizing flotation process-rougher concentrate regrinding" achieves the lowest concentrate yield of only 3.39%, the highest grade of up to 48.06%, and a recovery rate of 82.81%. It achieves a significant reduction in yield, a substantial increase in grade, and a slight decrease in concentrate recovery rate, making it suitable for product export schemes with a high proportion of freight costs.
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Safety Resilience Evaluation of Multi-Hazard Underground Mines Based on the PSR-Variable Weight Theory-Extension Cloud Model
Abstract:
To enhance safety levels during the mining process of multi-hazard underground mines and address issues such as high risks and frequent accidents, resilience theory is introduced to investigate risk response and post-disaster recovery capabilities. Firstly, an evaluation index system comprising 38 indicators is established based on the Pressure-State-Response (PSR) model from three dimensions: pressure, state, and response. Secondly, the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method is employed to determine the initial weights of the indicators, which are subsequently refined using variable weight theory. This approach compensates for the deficiency of traditional weighting methods that overlook the influence of actual indicator values on the final weights. Finally, an extension cloud model is applied to evaluate the safety resilience level of a specific multi-hazard underground mine, and an obstacle degree model is utilized to identify key barrier factors, thereby providing reference for improving resilience level. The research results indicate that the safety resilience of the studied multi-hazard underground mine is at a relatively high level. The response resilience dimension obstacle degree is 0.4170, which is the main obstacle dimension that restricts the improvement of resilience level. Specifically, roof stability (P3), regional stability (P4), safety education and training (R6), emergency rescue drills (R8), emergency material reserves (R9), and medical rescue response (R13) are the predominant obstacle factors, with respective obstacle degrees of 0.089, 0.076, 0.083, 0.079, 0.072, and 0.068. This study provides an effective quantitative evaluation method for the safety resilience of multi-hazard underground mines and offers a valuable reference for further improving the safety resilience of similar mining operations.
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Study on motion parameters' correlation and cutting performance of disc cutter based on rock strength
Abstract:
To improve disc cutter's adaptability in cutting rocks under complex conditions, a study on the matching relationship between rock strength and disc cutter's motion parameters is conducted. Simulation of disc cutter's axial vibration breaking rocks with different strengths is carried out based on central composite design. Response surface methodology is used to explore the influence law of disc cutter's radial cutting speed, vibration frequency and their interaction on rock breaking characteristics such as load, temperature and energy consumption, and through comprehensive evaluation of disc cutter's cutting performance under multiple factors and indicators, optimal combination of disc cutter's motion parameters under different rock strengths is proposed, the validity of the numerical model is verified through experiments. Results show that characteristic values such as load, temperature, energy consumption and rock breaking volume are all positively correlated with radial cutting speed, With increase of vibration frequency: load decreases; temperature and specific energy consumption increase; rock breaking volume remains basically unchanged; Interaction between radial cutting speed and vibration frequency on disc cutter's rock breaking characteristics in descending order of magnitude: total specific energy consumption, load spectrum mean value, circumferential temperature mean value and rock breaking volume; When rock strength is 19 MPa, the optimal motion parameter combination of disc cutter is 243.92 mm/s and 34.39 Hz; for rock strengths of 53 MPa and 91 MPa, the optimal motion parameter combination is 200 mm/s and 45 Hz, It is indicated that with increase of rock strength, reducing disc cutter's radial cutting speed and increasing vibration frequency is conducive to reducing disc cutter's wear and improving rock breaking efficiency, the radial load error between the experiment and the simulation was within the range of 15%, verifying the validity of the numerical model. It provides a reference basis for disc cutter's efficient and low-consumption cutting of rocks under complex conditions.
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Study on the effect of blasting pressure relief in deep roadways based on the distribution of butterfly plastic zone in surrounding rock
Abstract:
To investigate the effectiveness of blasting pressure relief on the surrounding rock of deep tunnel walls in gold mines, the crosscut tunnel of the Jinfeng Gold Mine in southwest Guizhou was selected as the engineering background. A numerical model of blasting pressure relief in a deep tunnel was established using FLAC3D. The stress concentration characteristics and plastic zone evolution of the surrounding rock were analyzed under different pressure-relief hole depths and spacings. The results indicate that pronounced stress concentration occurs in the unrelieved tunnel walls, with a stress concentration factor of 1.55, and that the plastic zone exhibits a typical butterfly-shaped distribution. With increasing pressure-relief hole depth, the peak vertical stress decreases by 2.68 MPa and shifts 3.23 m deeper into the surrounding rock. The optimal pressure-relief effect is achieved when the distance between the newly formed blasting-induced plastic zone on the tunnel walls and both sidewalls is approximately equal to the tunnel span. Excessively deep holes disrupt the bearing stress transfer path, resulting in a weakened rock mass structure. Meanwhile, the butterfly-shaped plastic zone gradually expands, and the butterfly wing angle evolves from extension along the principal stress direction to overall expansion perpendicular to the tunnel axis. When the spacing between pressure-relief holes is too small, stress wave superposition causes severe local rock fragmentation, whereas overly large spacing prevents effective penetration of the pressure-relief zone. Field application results demonstrate a 35.7% reduction in sidewall displacement and a transition of the anchoring system from rigid confinement to flexible sliding control. These findings provide valuable engineering guidance for the design of blasting pressure relief in similar deep tunnel projects.
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Pilot Study on Pyrometallurgical Lithium Extraction from Battery Black Mass — Sulfation Roasting-Alkali Leaching Process and Lithium Hydroxide Preparation via Bipolar Membrane Electrodialysis
Abstract:
This study conducted a pilot-scale investigation on the lithium extraction process involving sulfation roasting-alkaline leaching, using battery black powder derived from spent lithium-ion batteries as the raw material. Innovatively, the bipolar membrane electrodialysis (BMED) technology was introduced to address the challenges of difficult lithium-sodium separation and low product purity associated with conventional processes.Pilot-scale results demonstrated that under optimized process conditions, the lithium leaching rate reached 98.8%. Meanwhile, 99.65% of fluorine in the black powder was transferred into flue gas, resulting in an extremely low fluorine content in the leachate. The nickel-cobalt-manganese (NCM) residue obtained after alkaline leaching underwent two-stage countercurrent acid leaching, achieving leaching rates of over 99.2% for nickel, cobalt and manganese, thus realizing their efficient recovery.To tackle the problem of high sodium content in the alkaline leachate, bipolar membrane electrodialysis technology was adopted, which successfully converted the purified lithium sulfate solution into a lithium hydroxide solution with a hydroxide ion concentration of 1.38 mol/L and dilute sulfuric acid with a hydrogen ion concentration of 1.48 mol/L. After nanofiltration purification and evaporative crystallization, the lithium hydroxide solution yielded a product that meets the quality requirements of battery-grade lithium hydroxide.This process features simplicity and high efficiency, with an overall lithium recovery rate of approximately 97.9% throughout the whole process. Preliminary cost accounting indicated that the total processing cost for producing one ton of lithium was about 91,500 yuan. It exhibits favorable technical feasibility and economic competitiveness, providing a new approach for the resourceful and comprehensive utilization of spent lithium-ion batteries.
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Study on Properties and Main Controlling Factors of Bayer Process-Calcined Red Mud-Slag Alkali-Activated Backfill Cementitious MaterialDENG Daiqiang1,2, CHEN Yiru1,2, Zhang Shichao3, LI Buxian1,2, Hu Zhen1,2
Abstract:
To achieve the resourceful and high-value utilization of red mud, develop low-carbon cementitious materials for mine backfilling, and address the problems of environmental pollution caused by red mud stockpiling as well as the high energy consumption and high carbon emission of traditional Portland cement, this study takes Bayer process red mud calcined at 800℃ for 3 h and S95 granulated blast furnace slag as the main raw materials, and uses liquid sodium silicate and granular sodium hydroxide as the composite alkali activator. The L??(4?) orthogonal test is adopted to systematically explore the influence laws of red mud content, water glass modulus, alkali dosage, and water-binder ratio on the fluidity and setting time of the cementitious material slurry, as well as the 3 d, 7 d, and 28 d compressive strength of the cementitious material paste. The main control effect of each factor is clarified and the optimal mix ratio is determined.The main controlling factors were clarified and the optimal mix proportion was determined. The results show that water-binder ratio is the main controlling factor of fluidity and 3 d compressive strength, and water glass modulus plays a decisive role in 7 d and 28 d compressive strength. The increase of red mud content dilutes the activity of slag and reduces the early strength. At 28 d, 20% red mud can complement the activity of slag and reach the peak strength. The optimal mix proportion is 20% red mud, water glass modulus 1.8, alkali dosage 7% and water-binder ratio 0.38. This study provides experimental basis for the resource utilization of red mud solid waste and the engineering application of low-carbon cementitious materials.
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Fig.1 Preparation of Polystyrene Molded Polystyrene Board Material Specimens
Abstract:
Addressing the issues of low tunnel formation efficiency and high support costs associated with traditional one-step backfilling methods for pre-reserved tunnels, current pre-reserved tunnel techniques remain constrained by poor surrounding rock stability and insufficient buoyancy resistance of equipment in large void conditions, leaving these problems unresolved. This paper proposes a novel foam-structured reserved roadway technique within backfill bodies. Through structural device laboratory testing and computational analysis, its buoyancy resistance is optimized, complemented by construction methods including pre-fixed backfilling and staged backfilling. Field industrial trials demonstrate that this technique achieves construction efficiency comparable to drilling and blasting methods while reducing construction costs by approximately 27%. It minimizes damage to surrounding backfill bodies and lowers support requirements. These findings provide valuable reference for safely and economically reserving roadways within backfill bodies in large void conditions at similar mines.
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Comprehensive Recovery and Utilization of Valuable Metals from Bayer Process Red Mud: A Research Review
Abstract:
To address the environmental hazards posed by red mud stockpiling in Bayer process alumina production while achieving efficient utilisation of secondary resources, this paper systematically examines the fundamental characteristics and environmental impacts of Bayer process red mud. It focuses on the current state of research into recovering valuable metals such as Fe, Al, Ti, and Sc, conducting an in-depth comparison of the operating principles and industrial performance of various recovery processes. The analysis evaluates the advantages, disadvantages, and suitable applications of each process. Findings indicate that physical methods for Fe recovery offer simplicity but yield rates of merely 55%–60%, whilst reduction roasting followed by magnetic separation achieves 87%–92.8% recovery at higher energy consumption. Acid leaching demonstrates high leaching rates for Al, Ti, and Sc but incurs substantial acid consumption, while combined processes enhance overall recovery efficiency at the cost of greater procedural complexity. The comprehensive utilisation rate of red mud has now reached approximately 12%, yet it still lags behind developed nations. Research indicates that phase control, green process development, combined process innovation, and the preparation of high-value materials from red mud represent core future directions for valuable metal recovery from red mud, offering reference points for technological advancement within the industry.
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Multi source feature fusion for adaptive fault diagnosis of guide bar fracture in mining electromechanical equipment
Abstract:
To address the issues of weak fault characteristics of rotor bars in mining mechanical equipment under dusty and variable load conditions, as well as the poor adaptability of traditional diagnostic methods to different working conditions, a fault diagnosis method for rotor bar fractures based on multi-source feature fusion and adaptive to working conditions is proposed. This method uses stator current, bearing seat vibration acceleration, and air gap magnetic field as multi-source diagnostic signals. After differentiated targeted preprocessing, 8-dimensional fault-sensitive features are extracted hierarchically. Feature-decision two-level fusion is achieved through PCA dimensionality reduction and weighted voting. A working condition adaptive threshold adjustment mechanism is combined with load rate and rotational speed. The results show that when the non-bar fracture fault samples account for 20%, the diagnostic accuracy of the training set of this method reaches 96.48%, with the precision rate, recall rate, and F1 value being 95.82%, 94.96%, and 95.39% respectively. In pure mining actual test data, the diagnostic accuracy remains above 90%, and the real-time diagnostic response time is only 29.68ms. This method can achieve precise identification and classification of rotor bar fractures under complex working conditions and is suitable for the engineering diagnostic requirements of mining mechanical equipment.
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Mechanism of the Influence of Nano-SiO2 on the Evolution of Early Hydration Products in Filled Gel Systems
Abstract:
To elucidate the mechanism by which nano-SiO2 (NS) influences the evolution of early hydration products in cementitious gel systems, this study employed microscopic experimental techniques to investigate the effects of nano-SiO2 on the formation patterns of hydration products such as calcium silicate hydrate (C-S-H), calcium hydroxide (CH), and calcium aluminate hydrate (AFt). The results indicate that nano-SiO2 primarily influences the evolution of hydration products through nucleation and filling effects. The incorporation of nano-SiO2 accelerates and promotes the early hydration reactions of cementitious minerals, helping to increase the yield of hydration products, enhance the density of the matrix, and optimize the C-S-H gel structure. The loading level and dispersion of nano-SiO2 have a significant impact on the microstructural development of the composite. At a dosage of 1.5%, the nanoparticle distribution is relatively uniform, promoting the formation of hydration products, precipitation, and the development of a gel network, thereby effectively improving the density of the matrix. When the addition level increases to 2.5%, the filling and nucleation effects are weakened due to the agglomeration of nanoparticles, and the formation of hydration products and the rate of precipitation slow down. In addition, due to the uneven distribution of nano-SiO2 in the grouting slurry, localized hydration reactions occur within the grout. Therefore, incorporating an appropriate amount of nano-SiO2 while ensuring good dispersion is an effective approach to enhancing the performance of the filler. This research holds significant importance for safe mining operations and the development of green mines.
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Study on the mechanism of energy release and induced impact and pressure relief regulation technology of overlying strata fracture in steep and extremely thick coal seam
Abstract:
Due to its complex geological structure, high-stress environment, and unique mining technical conditions, the mechanisms of rock burst occurrence and the corresponding prevention and control measures for steeply inclined and extremely thick coal seams are significantly different from those for nearly horizontal or gently inclined coal seams. In this study, a comprehensive research approach combining discrete-continuous coupled numerical simulation and on-site monitoring was employed. The energy accumulation patterns and rock burst manifestation characteristics of steeply inclined and extremely thick coal and rock masses during the mining process were systematically analyzed. The evolution processes of the macroscopic and mesoscopic structures of the surrounding rock in the mining roadway, as well as the mechanisms underlying rock burst occurrence, were revealed. Furthermore, a coordinated deep and shallow hole blasting technique for pressure relief was proposed as an effective Rock burst prevention and control strategy. Research indicates that as mining operations extend to greater depths, the primary source of energy release progressively transitions from the coal seam itself to the surrounding roof strata and rock pillars. The return airway located within 200 meters ahead of the coal mining face in the B3-6 coal seam constitutes a high-risk zone for rock burst occurrences. Typical failure modes in this area include roof subsidence, rib spalling at the shoulder angles, and floor heave. Influenced by mining activities, the development of fractures and the redistribution of stress in the surrounding rock mass exhibit distinct stage-wise evolutionary characteristics. Notably, when the roadway is approximately 15 meters away from the working face, the intensity of mining-induced disturbances reaches its maximum. Under static loading conditions, the surrounding rock displays shallow fragmentation features along with a concentrated distribution of strong force chains in deeper regions. Dynamic loading disturbances can lead to the sudden rupture of these deep force chains, which subsequently causes the rock in the shallow fragmented zone to be violently expelled, ultimately initiating rock burst. Based on the above mechanism, a collaborative deep and shallow hole blasting pressure relief technology for the roof and rock pillar was proposed. After its engineering application, the proportion of microseismic events with an energy level of ≥10? J decreased to 0.2%. The total number of events increased to 30,947 times, while the number of high-energy events significantly decreased from 987 times to 64 times. The microseismic activity showed typical "low frequency and low energy" release characteristics, and no rock burst phenomenon occurred again. This research provides important theoretical support and engineering practice reference for the prevention and control of rock bursts under similar geological and mining conditions.
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Decoupling Relationship and Driving Factors Between Solid Waste Discharge of Mining and Mineral Processing and Economic Development in Mining Areas from The Perspective of New Quality Productivity
Abstract:
To promote the development of new quality productive forces and achieve the "dual carbon" target, coordinating the contradiction between economic growth and regional environmental issues in mining cities is crucial. This study employs the Tapio decoupling model, the Logarithmic Mean Divisia Index (LMDI) decomposition model and the decoupling effort model to analyze the decoupling relationship between solid waste discharge from mining and mineral processing in mining areas and economic development in the mining area of Chengde based on the data from 2017 to 2024, as well as the contribution levels of driving factors. It further evaluates the effectiveness of decoupling efforts for each driving factor. The research results indicate that solid waste discharge from mining and mineral processing and economic development in the mining area of Chengde are in a state of expansive coupling, the evolution path of the decoupling relationship is as follows: recession decoupling (2017-2018), expansive negative decoupling (2018-2021), strong decoupling (2021-2022), expansive negative decoupling (2022-2024). At the county scale, there are significant differences in decoupling statuses and the contributions of driving factors, leading to the identification of four patterns: technology-locked, structure-optimized, resource-declining, and transition-phase. The economic scale effect is the primary driving force behind the increase in solid waste discharge from mining and mineral processing, while the emission intensity effect is the key factor hindering decoupling. Although the industrial structure effect generally inhibits emissions, it exhibits significant fluctuations, the population effect manifests as scale-reduction-type emission reduction, a model that relies on population size contraction rather than improvement in human capital quality, which is incompatible with the development requirements of new quality productive forces. The evaluation of decoupling efforts shows that, during most periods of the study, the total decoupling effort index is negative. The coordinated development of factors such as technological innovation, industrial upgrading, and human capital plays a positive role in promoting the decoupling of solid waste discharge from mining and mineral processing in mining areas.
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Study on the Pore Structure of MICP Uranium Tailings Cemented Bodies under Wet-Dry and Freeze-Thaw Cycles Based on NMR-CT Technology
Abstract:
To study the changes in the pore structure of MICP-uranium tailings cemented bodies formed after uranium tailings are treated with microbial induced calcium carbonate precipitation (MICP) under dry-wet and freeze-thaw cycles, a combination of nuclear magnetic resonance (NMR) and computed tomography (CT) techniques was used to analyze the evolution of pore structure and pore networks in uranium tailings cemented bodies under different cycle numbers. Additionally, pore network models were constructed using Avizo, and the results of pore structure changes were validated through microscopic morphology analysis (SEM). The results show that pores develop rapidly during 0 – 6 cycles, with many pores interconnected to form throats; after 6 cycles, pore development slows down, throats become fully developed, and the cycles start to damage the calcium carbonate cement. The more cycles, the stronger the impact of cycling on the pore structure. These results can provide a reference for the durability study of MICP cemented uranium tailings.
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Analysis of the Impact of Concentration Parameter Values on Flood Control Safety of Tailings Pond
Abstract:
Tailings ponds are often located in mountainous areas with scarce hydrological monitoring data,and the rational formula method is widely used for estimating design floods.In this method,determining the convergence parameter m is critical,as its accuracy directly affects the project scale design,safety reliability,and overall socioeconomic benefits.However,in practical engineering design and safety evaluations,sufficient attention is often not paid to the selection of this parameter,leading to significant errors in the calculated results and compromising the rationality and safety of the project.It should be recognized that the convergence parameter m is not only influenced by natural geographical conditions such as underlying surface characteristics of the watershed but also involves dynamic coupling and nonlinear feedback interactions with hydrological elements such as peak discharge and convergence time.Taking the Delni Copper Mine tailings pond as an example,this study focuses on the value of parameter m to improve the accuracy and applicability of the rational formula method in tailings pond design flood calculations.With reference to both the Design Code for Flood Calculation of Water Resources and Hydropower Engineering and the Qinghai Provincial Hydrological Manual,a range of values for m was determined,and the response patterns of key hydraulic characteristics-such as convergence time,peak discharge, and average flow velocity-to variations in m were systematically investigated.The research shows that parameter m exerts a highly significant regulatory effect on peak flow,a mechanism that has not been adequately emphasized in previous studies.Given that most tailings pond catchments fall into the category of very small watersheds, it is recommended that,based on systematic analysis of topographic,geomorphic,and vegetation coverage characteristics supplemented by field surveys,the concept of “localization adaptation and multi-dimensional validation” should be adopted to scientifically determine the value of m.This approach would significantly enhance the scientific soundness and reliability of tailings pond design and construction.
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Effect of Silica Fume on Mechanical Properties and Microstructure of Cemented Backfill
Abstract:
In order to study the influence of silica fume on the performance of cemented backfill, silica fume was used to partially replace cement at replacement ratios of 0%, 5%, 10%, 15%, and 20% for the preparation of cemented backfill. Uniaxial compression tests were conducted to investigate the strength evolution characteristics, and X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) were employed to reveal the intrinsic mechanisms by which silica fume regulates backfill performance. The results indicate that the incorporation of an appropriate amount of silica fume significantly enhances the mechanical properties of cemented backfill, with the 10% replacement level being optimal. At a curing age of 28 days, the uniaxial compressive strength of the 10% silica fume mixture reached 5.30 MPa, representing an increase of 12.53% compared with the control group. The strengthening effect of silica fume on the middle stage of filling body is more obvious. The compressive strength of the 10 % dosage group at 7d age is 35.39% higher than that of the control group, while the increase of 3d and 28d age is small, which is 10.16% and 12.53%. XRD analysis shows that the incorporation of silica fume leads to a marked increase in C-S-H gel content, accompanied by a significant reduction in Ca(OH)2. SEM observations reveal that the C-S-H gel tightly binds solid particles into an interwoven structure, thereby enhancing the microstructural densification of the backfill. MIP results indicate that the total pore volume of the 10% silica fume group decreases from 0.096 ml/g (control) to 0.086 ml/g, corresponding to a reduction of 12%. In summary, the partial replacement of cement by silica fume can improve the performance of cemented backfill while reducing the amount of cement, which provides theoretical support for the study of green cementitious materials.
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A Gaussian Process Mixture Model Based on Physical Constraints for Post-Blasting Rock Block Size Modeling
Abstract:
The fragment size distribution of blasted rock is a critical indicator for evaluating blasting performance in mining operations, as it directly affects the efficiency and energy consumption of loading, hauling, and primary crushing, and ultimately influences the overall economics and safety of the mining system. To address the limited accuracy of traditional empirical models and the lack of physical consistency in purely data-driven approaches, this study proposes a Physics-Informed Gaussian Process hybrid model (PIGP) for predicting post-blast rock fragment size distribution. The proposed model first employs an optimized baseline model to capture the global mapping between blasting parameters and rock fragmentation characteristics. A Gaussian process is then introduced to nonparametrically model the prediction residuals, enabling effective representation of local nonlinear behaviors and uncertainty. During training, a monotonicity constraint associated with the rock elastic modulus is incorporated into the loss function in the form of a penalty term, guided by a dynamic scheduling strategy, thereby enforcing consistency with the underlying blast energy propagation mechanism.Experimental results based on multi-mine blasting datasets demonstrate that the proposed PIGP model achieves a coefficient of determination (R2) of 0.873, with a root mean square error (RMSE) of 0.046 and a mean absolute error (MAE) of 0.035, significantly outperforming mainstream machine learning models such as Random Forest and XGBoost. Ablation studies further confirm the necessity of both the baseline prior and the physics-informed constraint for improving prediction
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Study on the Mechanical Properties of Granite and the Accumulative Damage under Secondary Loading at Different Post-Peak Stages
Abstract:
Routine uniaxial compression, triaxial compression, and Brazilian splitting tests were conducted to investigate the mechanical properties of granite. Secondary loading was applied at different stages after the peak to further reveal the damage accumulation patterns of the rock. The results indicate that: (1) In uniaxial compression tests, granite primarily exhibited splitting failure; under triaxial compression, with confining pressures increased to 15–50 MPa, failure transitioned to shear. The stress–strain curve displayed linear elastic characteristics before the peak and brittle drop after the peak. (2) The uniaxial compressive and tensile strengths of granite were 220.33 MPa and 9.71 MPa, respectively, with an elastic modulus ranging from 59.78 to 62.24 GPa and a Poisson’s ratio between 0.17 and 0.22. The peak strength, residual peak strength, residual strength, and cohesion of the rock were positively correlated with confining pressure, while the internal friction angle decreased as confining pressure increased. (3) Changing the loading path did not result in a transition from brittle to ductile behavior in the stress–strain curve. The strength response of the rock during secondary loading after the peak was closely related to the damage accumulated during initial loading: when initially loaded to peak strength, the rock was in a "critical failure" state, with damage not fully developed, allowing the rock to still recover considerable load-bearing capacity during secondary loading; when initially loaded to about one-fifth of the post-peak drop, through-thickness cracks formed within the granite, significantly reducing the residual strength under secondary loading. Higher confining pressure could suppress damage development, and the rate of residual strength decay decreased with increasing confining pressure. (4) Measurement of wave velocity during unloading tests revealed that under different loading paths, the axial wave velocity after unloading first decreased and then increased with rising confining pressure, which was also related to the rock’s failure mode. These findings provide important reference for evaluating the stability of surrounding rock in granite formations for engineering purposes.
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Pillar Safety Factor Prediction Model Based on CCO-XGBoost and SHAP Interpretation Framework[1]
Abstract:
The assessment of pillar stability constitutes a core element in the safe underground mining operations. Accurate prediction of the pillar safety factor holds significant importance for preventing collapse incidents. Addressing the issues of arbitrary parameter selection and susceptibility to local optima inherent in traditional machine learning models, this paper proposes a pillar safety factor prediction model (CCO-XGBoost) based on an XGBoost algorithm enhanced by the Cuckoo Catfish Optimisation (CCO) algorithm. This approach leverages the CCO algorithm's unique spatial compression mechanism, spiral search strategy, and chaotic predation strategy to achieve adaptive optimisation of key XGBoost hyperparameters, including learning rate, maximum tree depth, and regularisation weight. Comparative experiments with mainstream algorithms, including BPNN, SVR, RF, PSO-XGB, and GWO-XGB, demonstrate that the CCO-XGBoost model possesses superior convergence speed and generalization ability, achieving the lowest Root Mean Square Error (RMSE=0.028) and the highest Coefficient of Determination (=0.978) on the test set. Based on the verification of the model's superiority, the Pearson Correlation Coefficient and the SHAP game theory method were further employed to analyze the model's interpretability. The results reveal that pillar width has the strongest positive correlation with the safety factor, while room width exhibits a negative correlation. Moreover, SHAP dependence plots quantify the non-linear threshold effects of each feature, identifying 8 m as a critical threshold dimension for pillar width. This study not only significantly improves prediction accuracy but also successfully opens the model's "black box," providing a scientific and transparent intelligent decision-making tool for mine safety evaluation.
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Strength and Energy Evolution Law of Coal-Based Solid Waste Backfill at Different Loading Rates
Abstract:
The mechanical behavior of coal-based solid waste backfill is fundamental to mix-design optimization and engineering application, and the loading rate exerts a pronounced influence on its measured mechanical performance, thereby affecting the stability and safety of backfilled stopes in complex mining environments. To clarify the mechanical response of the backfill under different loading rates, uniaxial compression tests coupled with acoustic emission (AE) monitoring were conducted to analyze its strength development, energy evolution, and crack-propagation behavior. The results show that the peak strength increases as the loading rate rises from 0.6 mm/min to 1.8 mm/min, but decreases when the rate further increases to 3.0 mm/min. Peak strain and elastic modulus exhibit the same trend, with a critical loading rate of approximately 1.8 mm/min. The highest pre-peak energy-storage efficiency occurs at moderate loading rates (1.8–2.4 mm/min). Failure at low loading rates is dominated by the slow propagation of a single principal crack, whereas high loading rates promote rapid microcrack initiation and subsequent multi-crack coalescence. The AE response also varies significantly with loading rate: under low rates, intensive ring-down activity is markedly delayed and occurs only near peak stress; under moderate rates, AE activity initiates earlier and becomes more concentrated, indicating enhanced synchronization between microcrack growth and energy release; under high rates, AE activity enters a dense stage almost simultaneously with stress increase and accumulates rapidly, reflecting frequent and persistent internal damage events.
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Study on the Solidification of Ultra-Fine Tailings for Backfilling and the Properties of Paste SlurryLIN Min1, WANG Qianyuan2, YUAN Qingmeng2
Abstract:
To address the limited understanding of the solidification behavior and slurry properties of classified overflow fine tailings, as well as the slow progress in their underground backfilling utilization, a small conical spread cylinder was employed to measure spread diameter for determining the paste concentration. Slag-based cementitious binders were adopted, and solidification tests and slurry property analysis were carried out on ultra-fine overflow tailings from middling streams in an iron mine, classified overflow fine tailings from several gold mines, and full tailings from multiple iron mines. The results show that slag-based binder powder can effectively meet the solidification and strength requirements of classified overflow ultra-fine tailings. Due to the high porosity and low bulk density of ultra-fine tailings, the paste concentration can be lower than 50%. Under the same binder dosage, ultra-fine tailings require a higher binder-to-tailings ratio; however, the reduction in 28 d strength is limited, resulting in only a slight increase in backfilling cost. In addition, slurry concentration has a significant influence on solidification strength. Under a filling gradient of 3.5–4.0, ultra-fine tailings paste slurry can be transported by gravity flow for backfilling without pumping.
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Design of an Electro Hydraulic Monitoring and Control System for Scraper Conveyor Based on the Kuanghong System
Abstract:
This study focuses on hardware design upgrades for the electro-hydraulic monitoring system of scraper conveyors, exploring a hardware platform based on the KuangHong operating system. A hardware architecture was developed by creating an adaptable platform that replaces existing programmable logic controller components. Leveraging KuangHong’s soft bus capabilities, the system enables multi-device wireless coordination, supports an intelligent working face mode for "one device controlling multiple units," and ensures reliable data transmission through multi-mode communication and the MDTP protocol, significantly enhancing operational intelligence. The hardware utilizes domestically developed chips, reducing supply chain risks associated with foreign technology. The control system has been successfully deployed at China Coal Group’s Yamai Daning Coal Mine, where four units accurately collect data from 50 sensors on the conveyor’s drive section and transmit it in real time via the soft bus to the central control center, enabling continuous status monitoring .
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Application of Wireless Real-Time Ground Pressure Monitoring Technology in Deep Mining of Macheng Iron Mine
Abstract:
As metal mining extends to greater depths, the risk of ground pressure hazards induced by mining activities under high ground stress environments intensifies. Constructing a real-time and effective ground pressure monitoring system is of great significance for ensuring safe and efficient production in mines. Based on the deep backfill mining engineering practice at the Macheng Iron Mine, rock mechanics tests were conducted on granite and iron ore, and a KJ21 wireless ground pressure monitoring system was developed based on an "Optical Fiber Ethernet Ring Network (OFERN) + Time Division-ZigBee (TD-ZigBee) wireless transmission." Four-level warning thresholds were established in conjunction with rock mass mechanical parameters, and 97 monitoring points were deployed at key production levels from -480 m to -930 m for engineering applications. The results indicate that the system achieves real-time collection and stable transmission of multi-parameters in deep complex environments, reducing manual inspection frequency by more than 50%. Monitoring data reveal a high correlation between borehole stress changes and mining disturbances. For instance, the stress at monitoring point A1# on the -480 m level increases from 4.5 MPa to 6.2 MPa during blasting and recovery, and subsequently decreases after the backfilling process begins, verifying the sensitivity and accuracy of the system's perception. The cumulative roof displacement in the hanging wall and footwall vein-following drifts remains generally small. The wireless real-time monitoring system operates stably with good scalability. The determined four-level warning thresholds provide scientific support for the prevention and control of ground pressure hazards in deep hard rock ore bodies, meeting the monitoring requirements under complex conditions in deep metal mines.
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Study on the Performance and Safety of Wet-Mix Shotcrete Prepared with Copper Slag
Abstract:
To promote the resource utilization of industrial solid waste and the development of green wet-mix shotcrete, this study prepared cement clinker-free solid waste-based wet-mix shotcrete using steel slag, slag, and desulfurized gypsum as cementitious materials, and copper slag, waste rock, etc. as aggregates. Systematic research was carried out through raw material property analysis, mix ratio optimization, performance testing, microscopic mechanism exploration, and on-site industrial tests. The results show that the mechanical properties of the solid waste-based wet-mix shotcrete with the optimal mix ratios (Samples No.5 and No.9) are superior to those of the cement-based system; the 7d compressive strength of Sample No.9 reaches 16.31MPa, and the 28d strength exceeds 28MPa. Its workability is equivalent to that of the cement-based system, and the slump and slump flow meet the requirements of wet-mix shotcrete operation. The solid waste-based cementitious system has a significant solidification effect on heavy metals, and the leaching concentrations of excessive Pb and Cd in copper slag are reduced to below the Class Ⅱ groundwater quality standard, showing excellent environmental safety. Microscopic analysis indicates that the solid waste-based system has abundant hydration products and high polymerization degree of silicate gel, which is the core reason for its excellent performance. On-site tests verify the feasibility of engineering application; although there are problems such as incomplete feeding, they can be improved through process optimization. This technology provides an effective path for the harmless disposal and resource utilization of copper slag and other solid wastes, and has comprehensive environmental, economic and social values.
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Dynamic–Static Coupling Optimization of Mining Parameters in Deep Underground Metal Mines under Blasting-Induced Disturbances
Abstract:
Deep underground metal mines are affected by long-term superposition of high in-situ stress and blasting-induced disturbances. Surrounding rock tends to exhibit stress concentration, cumulative roof subsidence, and intensified vibration, which threaten stope stability and production safety. Traditional mining parameter design mainly depends on experience and cannot balance stability and efficiency. Therefore, this study proposes a dynamic–static coupled optimization method for mining parameters. The method coordinately adjusts stope span, pillar width, filling height, and explosive unit consumption. The study uses a three-dimensional numerical model for dynamic response simulation and conducts field comparison tests. Results show significant improvements after optimization. The vibration velocity at 10 m decreases from 31.3 cm/s to 14.5 cm/s. The peak displacement of the bottom structure decreases from ?0.64 cm to ?0.18 cm. The cumulative roof subsidence within 24 h decreases from 9.8 mm to 4.1 mm. The maximum height of the roof plastic zone reduces from 8.6 m to 5.1 m. These findings demonstrate that the proposed method weakens blasting disturbance effects and improves surrounding rock stability. The method provides effective technical support for safe and efficient mining in deep underground metal mines.
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Research on disturbance failure analysis and support optimization technology of roadway near working face mining area
Abstract:
Aiming at the failure problem of concrete-filled steel tube support in roadways adjacent to working face mining area, the engineering background is a kilometer buried roadway in a mine. By using model test, numerical simulation and field test methods, the causes of support disturbance failure are systematically analyzed. With the help of numerical simulation, the whole process reappears the roadway failure process induced by working face advancing, and clarifies the dynamic evolution characteristics of surrounding rock stress field and plastic zone when the stop line is close to the roadway. The results show that when the stop line is 120 m away from the roadway, the mining stress concentration area and the roadway stress distribution area are superimposed for the first time. When the stop line is 80 m away from the roadway, the mining stress concentration factor increases from 1 to 1.25, the failure depth of the plastic zone of the surrounding rock of the roadway is 5 m, and the roadway is affected by the mining stress. When the stop line is 60 m away from the roadway, the plastic zone around the roadway is connected with the mining plastic zone of the working face, and the deformation of the surrounding rock increases significantly. Based on this, 80 m is selected as the reasonable width of protective coal pillar, and the stress distribution and displacement variation law of surrounding rock during the process of supporting reaction force increasing from 0.5 MPa to 3 MPa under this disturbance condition are analyzed. Furthermore, the stress evolution law of surrounding rock under disturbance load is studied by model test. Based on this, the mining control concept of ' reducing disturbance, strengthening support, and moderately yielding ' is proposed, and the corresponding optimization scheme of mining roadway support technology is designed. The engineering application shows that after the optimization scheme is adopted, the stable convergence of the top arc section, left side section, right side section and bottom arc section of the concrete-filled steel tube support is reduced to 68 mm, 17 mm, 88 mm and 42 mm respectively, and the roadway support state is stable, which provides a useful reference for similar deep mining roadway projects.
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Influence of fracture inclination on damage and acoustic emission properties of granite under true triaxial unloading
Abstract:
In order to reveal the mechanism of unloading and destabilizing damage of granite under the true triaxial stress environment after excavation of the deep surrounding rock to form a critical surface, a single-sided unloading test was conducted on the rock samples containing penetrating fissures. Relying on the high servo true triaxial test system, the unloading test was carried out on one side of the rock samples containing penetrating fissures, and the acoustic emission monitoring was synchronized. The degree of fragmentation was also quantitatively characterized by the debris sieving-fractal method. The results show that the prefabricated fracture significantly reduces the peak strength, and its weakening effect varies with α in a typical “V” shape, with the strongest at α=45° and the weakest at α=90°. Macroscopic damage is dominated by diagonal shear crack penetration, and the critical surfaces are accompanied by tensile spalling and the formation of rock burst craters with different morphologies. It shows that the fracture inclination can change the local energy release mode and collapse morphology by changing the stress concentration at the crack tip and the penetration path. The particle size distribution of the debris satisfies the fractal law, and the linear correlation of lg(M(r)/M)-lg(r) is good (R2>0.9). The fractal dimension D decreases and then increases with α. The value of D is the smallest when α=45° and the largest when α=90°. It reflects that the degree of fine fragmentation of the debris is characterized by non-monotonic evolution. The RA-AF results show that the different dip samples are dominated by tension cracking events, which are all greater than 79% of the total.Among them, the rock samples with α=30° have the highest proportion of shear cracks, which are more likely to induce sliding and shear rupture on the fissure surface.
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Experimental Study on Beneficiation of a Complex Refractory Sulfide Copper-Zinc Ore Bearing Pyrrhotite
Abstract:
Clayey minerals that are prone to slurry formation during grinding tend to produce fine mineral slimes, which deteriorate the flotation environment, increase reagent consumption, and significantly affect the grade and recovery rate of gold concentrates. This study aims to address the beneficiation challenges of this type of gold ore and achieve efficient resource recovery. The research focuses on a low-grade, easily slurry-forming gold ore. Based on a systematic study of its process mineralogy, the research explores the beneficiation process flow, ultimately determining a pre-desliming hydrocyclone, followed by a combined gravity-flotation process using a shaking table. The study sequentially optimizes parameters such as conditioner and collector types and dosages, conducting closed-circuit tests for both the combined gravity-flotation process and direct flotation. After pre-desliming with a hydrocyclone, the use of a shaking table for gravity separation can yield a gold concentrate with a grade of 22.69 g/t and a recovery rate of 21.64%. The tailings from gravity separation, when processed through a flotation circuit with two roughing stages, three scavenging stages, and two cleaning stages, can produce a flotation concentrate with a gold grade of 9.45 g/t and a recovery rate of 68.41%. Compared to direct flotation, the combined gravity-flotation process results in higher recovery rates of gold and silver, and the reagent costs are significantly lower than those of direct flotation. This study effectively addresses the efficient recovery of low-grade, easily slurry-forming gold ores and provides a reliable technical reference for similar gold mines.
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Research on the Application of UAV Ground-airborne Frequency-domain Electromagnetic Method in Coalfield Geological Prospect
Abstract:
To address the low efficiency and poor terrain adaptability of traditional ground-based geophysical methods in coalfield exploration across complex topography, this study verifies the applicability and effectiveness of UAV Ground-airborne Frequency-domain Electromagnetic Method in coalfield geological surveys. A typical complex-terrain coalfield was selected as the study area for systematic application research on UAV Ground-airborne Frequency-domain Electromagnetic Method. Numerical simulations were first conducted to clarify the electromagnetic response differences between coal-bearing strata and surrounding rock, validating the reliability of apparent resistivity imaging. Subsequently, full-process data acquisition, processing, and imaging were carried out for 9 survey lines, covering 28.8 km and 2,514 measurement points, to obtain subsurface electrical structure information for the study area. This data was then integrated with regional geological and seismic data for combined inference and interpretation. Results indicate that the spatial distribution characteristics of low-resistivity anomalies reflected by this method align with known patterns of coal-bearing strata variations, effectively identifying major faults and stratigraphic interfaces. Compared to traditional ground-based geophysical methods, this approach achieves at least a fivefold increase in operational efficiency. Conclusions suggest that this method, leveraging its flexible and efficient operational model, overcomes limitations imposed by complex topography, significantly enhances exploration efficiency, and can serve as a crucial technical tool for geological exploration in coalfields with complex terrain.
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Effect of fracture dip angle on damage evolution path and elastic-dissipation energy distribution of sandstone under cyclic loading and unloading conditions
Abstract:
To investigate the influence of fracture inclination angle on the damage evolution and failure mechanisms of sandstone under cyclic loading and unloading, sandstone specimens containing through-going fractures with inclination angles ranging from 0° to 90° were prepared. Uniaxial multi-stage cyclic loading–unloading tests were then conducted. Acoustic emission (AE) and digital image correlation (DIC) techniques were jointly applied to synchronously monitor the mechanical response, AE characteristics, and full-field strain evolution of the specimens. The results demonstrate that fracture inclination angle exerts a pronounced control on the strength, deformation behavior, and failure mode of sandstone. Specimens with low fracture inclinations (0°~30°) show relatively rapid damage accumulation during cyclic loading. Pronounced crack propagation occurs prior to peak stress, and failure is characterized by ductile behavior. At intermediate inclination angles (approximately 45°), shear effects dominate, and the proportion of shear cracks reaches its maximum. In contrast, specimens with high fracture inclinations (60°~90°) are governed by elastic energy accumulation. Crack activity is suppressed before failure, which is followed by sudden brittle rupture. For all specimens, a marked surge in acoustic emission energy is observed near the instability stage, indicating an accelerated evolution of internal damage. Further energy analysis reveals that fracture inclination angle controls the damage evolution pathways and instability modes of sandstone under cyclic loading by regulating the partitioning between elastic energy storage and dissipated energy. These findings provide a theoretical basis for evaluating the stability of fractured surrounding rock subjected to cyclic disturbances.
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Research on Vegetation Information Extraction and Coverage Prediction Method for Mining and Stripping Disturbance in Open pit Mining Areas
Abstract:
During the open-pit mining process, stripping operations, soil dumping, and transportation activities continue to alter the surface structure, resulting in a mixed vegetation, exposed ore bodies, and disturbed surface heights within mining engineering units such as mining pits, soil dumping sites, industrial plazas, and reclamation areas. This poses significant challenges to accurately obtaining and dynamically evaluating vegetation coverage in mining areas. Aiming at the problem of insufficient recognition accuracy of traditional single vegetation index in complex mining areas, a vegetation information extraction and coverage prediction method for mining area applications has been developed. This method constructs a two-dimensional feature space by integrating normalized vegetation index and dry fuel index, and combines linear mixed pixel decomposition to achieve precise inversion of vegetation coverage in mining areas; On this basis, the swarm intelligence optimization strategy is introduced to adaptively optimize the parameters of the time series prediction model, and a coverage evolution trend prediction model is established. The study focuses on typical open-pit coal mining areas, conducting verification experiments centered around key mining functional zones such as the mining pit area, waste dump, and reclamation area. The experimental results indicate that the proposed vegetation coverage inversion method, based on a two-dimensional feature space of normalized vegetation index and dead fuel index, achieves an overall mean absolute error of 0.034 and a root mean square error of 0.048 in the task of vegetation coverage inversion in mining areas, with a determination coefficient reaching 0.92. The long short-term memory network prediction model optimized based on the sparrow search algorithm exhibits an average absolute error of 0.029 in coverage time series prediction and a determination coefficient of 0.94, effectively depicting the vegetation evolution process under disturbance conditions. The research findings demonstrate that this method can effectively enhance the extraction accuracy and time series prediction capability of vegetation coverage information in mining areas, providing technical support for the acceptance inspection of ecological restoration projects in open-pit mining areas, ecological management assessment of waste dumps, and dynamic supervision of green mines.Keywords: Open-pit mining area; Mining disturbance; Disposal sites and mining pits; Vegetation coverage; Time series prediction; Green Mining and Ecological Restoration Assessment
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Benefit Comparison and Optimization Strategies of Different Vegetation Patterns in Ecological Restoration of Abandoned Mines—A Case Study of the Abandoned Mine Restoration Project along the Railway in Qinyang City, Henan Province
Abstract:
As a major mineral resource province in China, Henan faces urgent challenges of land degradation, vegetation destruction, and soil pollution caused by abandoned mines. This study focused on the abandoned mine restoration area of Chenzhuang along the railway in Qinyang City, where artificial Platycladus orientalis forest land, grassland, and forest-grass composite plots were established. We systematically measured plant biomass, vertical distribution of soil organic carbon (SOC) content, and carbon density (SOCD) to reveal the ecological effects and mechanisms of different vegetation restoration modes. The results showed that: ① Vegetation species composition exhibited significant environmental adaptability, with arbor dominated by medium-growth Platycladus orientalis (tree heights of 2.0–3.0 m accounting for 68.1% and diameter at breast height (DBH) of 1.0–3.5 cm accounting for 83.3%), and herbs consisting of drought-tolerant pioneer species (e.g., Setaria viridisand Poa sphondylodes). ② In terms of biomass, the forest-grass composite plot performed optimally: its aboveground biomass (209 g/m2), litter (251.44 g/m2), and belowground biomass (258.01 g/m2) were all significantly higher than those of single forest land and grassland. Specifically, compared with single forest land, the aboveground, litter, and belowground biomass of the forest-grass composite plot increased by 942%, 58%, and 1384%, respectively; the increase was even more pronounced relative to grassland. The forest-grass composite plot maintained a balanced biomass proportion across vertical strata (25% aboveground, 39% litter, 36% belowground), breaking resource competition via arbor-grass functional complementarity. ③ Regarding soil carbon sequestration capacity, the forest-grass composite mode demonstrated distinct advantages: its SOC exhibited the most uniform vertical distribution (0–60 cm: 8.34–7.80 g/kg), with SOCD increasing by 78.7% with depth, achieving synergistic rapid surface carbon accumulation and long-term deep carbon storage. In contrast, single forest land relied primarily on litter for carbon accumulation, resulting in relatively concentrated carbon distribution; grassland, due to its shallow root system and low litter biomass, had carbon input confined to the surface layer, leading to a declining trend in the lower carbon pool. In conclusion, the forest-grass composite mode effectively balances short-term vegetation productivity enhancement and long-term soil improvement. It is recommended to prioritize this vegetation configuration in similar abandoned mine ecological restoration projects, providing a scientific basis for optimizing vegetation schemes and promoting coordinated eco-economic development.
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Research on Multi-Coal Type Recognition Based on Improved Multi-Level Fusion Clustering Algorithm
Abstract:
In the coal storage process of a coal preparation plant, the lack of effective identification methods for multiple coal types leads to reliance on worker experience during binning storage, which is prone to significant human errors and economic losses. To address this issue, based on real coal composition data obtained from a coal quality analyzer in a coal preparation plant in North China, a multi-coal type identification model is established using an improved multi-level fusion clustering algorithm. Firstly, on the basis of ceemdan data denoising, a ccKL-greedy dimension and hierarchical control layer are established to construct a multi-level PCA feature extraction framework that comprehensively utilizes local features and adaptively adjusts parameters through a feedback loop. Secondly, the Critic algorithm is used for weighted fusion of each layer, and the K-means++ algorithm is combined to cluster the fused deep features. Finally, label comparison is performed to achieve sample identification. Comparative experimental results show that the improved multi-level fusion clustering model improves the silhouette coefficient by 29.7%, reduces the Davids-Boulding index by 14.1%, and increases the Calinski-Harabasz score by 36.5% compared to traditional K-means++. In various noise interference tests with robustness ranging from 3% to 10%, except for individual fluctuations up to 3.6%, the indicator changes under other noises are all controlled within 2%, demonstrating stable performance and superiority over comparative methods. While improving clustering accuracy, it retains low computational complexity and has potential for industrial application.
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Research on Integrated Exploration Technology for Coal and Associated Mineral Resources
Abstract:
Through innovative exploration methods, optimized mining techniques and intelligent collaborative technologies, the efficient and coordinated development of coal and associated minerals (such as coalbed methane, shale gas, rare metals, etc.) in coal-bearing strata is achieved, thereby enhancing the comprehensive utilization rate of resources, reducing mining costs, and minimizing environmental disturbances. This also promotes the transformation and upgrading of the green and low-carbon development model of mineral resources, providing technical support for the national energy security strategy and the "dual carbon" goals. For the first time, from the perspectives of strategic resource allocation, innovation in mining rights and management mechanisms, and ecological and resource coordination, the national policy guidance on the integrated exploration and mining of coal and associated minerals is deeply interpreted. Secondly, it focuses on analyzing the eight predicaments faced by the comprehensive utilization of coal and associated minerals, including the difficulty in extracting low-grade resources, the difficulty in separating complex components, the inversion of development costs, the absence of market mechanisms, the fragmentation of systems and mechanisms, the difficulty in implementing incentive policies, the existence of inherent disadvantages, and the pressure of ecological restoration. Finally, it elaborates on the technical paths for the integrated exploration and mining of coal and associated minerals, including comprehensive exploration, comprehensive mining, policy and spatial management, resource evaluation and quality control. These include the application of "air-ground-space" integrated collaborative exploration technology, the application of multi-field coupling collaborative evaluation technology, the application of zonal and staggered time-coordinated mining technology, the application of underground-drilling-coal mining collaborative development technology, the optimization of mining area planning and layout and mining rights allocation, the construction of a green collaborative development system, the establishment of a full-process standardized sampling and testing system, and dynamic economic evaluation and resource classification. The integrated exploration and mining technology of coal and associated minerals, through the cross-disciplinary integration and technological innovation, realizes the coordinated development and efficient utilization of resources in coal-bearing strata, and builds a "exploration-mining-utilization" full-chain technology system. It provides a systematic solution to the resource waste and ecological pressure brought about by the traditional single development model, marking a key step towards the green, intelligent and intensive development of mineral resources.
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Study on Grouting Methods for Water-Conducting Anomaly Zones in Rock Strata Considering Water Displacement Effects
Abstract:
In coal mine floor strata threatened by confined water, water-inrush disasters are often induced by the presence of water-conducting structures, and the efficient diffusion of grout in grouting treatment becomes key to blocking water hazards. This study investigates the mechanism of grout diffusion driven by the "grout pressure–water flow" in rock strata grouting using the two-phase flow calculation method in computational fluid dynamics. Based on a typical water-conducting anomaly zone in coal mine engineering, an optimization method for grouting borehole layout is proposed. The results show that under the dual driving forces of "grout pressure–water flow," the grout exhibits a quasi-parabolic diffusion pattern centered around the borehole. In the direction of water flow, grout diffusion shows a significant linear enhancement effect, while lateral diffusion is linearly suppressed. For water blockage, an optimized multi-hole segmented grouting method with a spatially staggered effect should be adopted to effectively avoid untreated zones. This research can provide theoretical and technical guidance for advanced treatment and emergency rescue in structural zones of coal seam floors.
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Microseismic Localization of Deep buried rock Using Particle Swarm Optimization with Chaotic Mapping and Opposition-Based Learning
Abstract:
Microseismic localization is crucial for monitoring and warning rockbursts in deep rock mass engineering such as mines, and its accuracy and efficiency directly affect rockburst risk identification. In response to challenges such as the complex solution space, strong nonlinearity, and susceptibility to local optima in microseismic localization, this paper systematically investigates the application of swarm intelligence optimization algorithms in microseismic localization. By comparing the performance of the SSA, DE, and PSO in single P wave localization, it is found that PSO performs best in terms of solution stability. To further enhance localization accuracy and robustness, S waves are incorporated to establish a dual-wave joint localization model, reducing the inversion space from four dimensions to three. Experiments demonstrate that dual wave joint localization significantly outperforms single P wave localization, with PSO achieving the lowest average error in joint localization, indicating strong adaptability. To address the limitations of PSO such as premature convergence and sensitivity to initial conditions, an APSO algorithm integrating opposition based learning and chaotic mapping is proposed. Opposition based learning is employed to generate a high quality initial population, while chaotic mapping enables dynamic adjustment of inertia weight to balance global exploration and local exploitation capabilities. Numerical simulation results show that APSO outperforms the standard PSO across multiple typical source points, reducing the average localization error by approximately 62.4%, while also demonstrating better stability and convergence efficiency across monitoring points. This method provides an effective tool for high precision microseismic localization in deep rock mass engineering, with promising prospects for practical application.
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Study on the Variability of Deformation and Failure Characteristics in Tunnel Surrounding Rockmass under Different Stress Orientation Conditions in Deep Metal Mines
Abstract:
The relative relationship between the maximum principal stress in deep metal mines and the staggered arrangement of roadways often leads to differential characteristics in roadway rock mass failure, resulting in the ineffectiveness of conventional support methods. This study employs a combined approach of borehole deformation monitoring, microseismic monitoring, and numerical simulation to investigate multiple types of deformation failure phenomena in a deep iron mine roadway. It reveals the differential patterns of roadway rock mass deformation and failure under varying stress direction conditions,and proposed an optimized plan for differentiated support in mine tunnels. The results indicate: When the tunnel strike is orthogonal to the maximum principal stress direction, the microseismic energy index indicates high stress concentration zones distributed at the tunnel crown and shoulders, with relatively high average microseismic event energy. The cumulative deformation of the surrounding rock is significant, and deformation varies at different depths within the rock mass. For tunnels parallel to the maximum principal stress direction, high stress concentration zones are small and primarily localized at the sidewall positions, leading to a concentration of microseismic events at these locations. The stress, strain, and plastic zone evolution patterns obtained from numerical simulations for both tunnel layouts are consistent with in-situ monitoring results. Based on the mechanism of differential failure, a differentiated support scheme was proposed: for roadways perpendicular to the direction of the maximum principal stress, where stress concentration in the roof area is pronounced, support strength was enhanced by reducing the spacing between anchor bolts and thickening the sprayed concrete layer; for roadways parallel to the direction of the maximum principal stress, where failure characteristics in the sidewall area are more pronounced, sidewall support was reinforced by increasing the density of sidewall anchor bolts.
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Influence of Confining Pressure on the Mechanical and Permeability Evolution Characteristics of Sandy Mudstone
Abstract:
To elucidate the evolution mechanisms of mechanical and seepage characteristics in sandy mudstone under varying confining pressure conditions, triaxial stress-seepage coupling tests were conducted on sandy mudstone at confining pressures of 5, 10, 15, and 20 MPa. The study investigated the influence of confining pressure on its mechanical properties, permeability, and fracturing patterns. Research findings indicate that as confining pressure increases, the post-peak drop in stress-strain curves gradually slows, with significant increases in peak strength and elastic modulus of rock specimens. Specimen fracture morphology evolves from simple through-going fractures towards bent, multi-branched, and complex network patterns. The average inclination angle of primary fractures progressively decreases from 76° to 67°. The full-process permeability curve of the rock sample can be divided into four distinct phases: a slight decrease, a gradual increase, a sudden surge, and a subsequent decline. As confining pressure increases, the initial permeability and peak permeability of rock samples gradually decrease, the onset of permeability jump shifts later overall, and the magnitude of the permeability jump diminishes. As the confining pressure increased from 5 MPa to 20 MPa, the average initial permeability gradually decreased from 4.57×10-7 D to 1.21×10-7 D. The average peak permeability decreased from 72.74×10-7 D to 5.39×10-7 D, and the permeability jump amplitude decreased from 68.17×10-7 D to 4.18×10-7 D. During the decline phase of the permeability curve, following the overall failure of the rock sample, the primary fracture undergoes displacement and closure under confining pressure. Concurrently, rock debris and powder generated by friction migrate and obstruct the flow pathways, causing permeability to rapidly drop to a lower level. The research findings provide experimental evidence for controlling the stability of tunnel surrounding rock and preventing seepage-related hazards.
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Mechanical Properties and Microstructural Evolution of Multi-Source Solid Waste Uranium Tailings Composite Backfill Materials
Abstract:
Uranium tailings are a type of large-volume, very-low-level solid waste, and cemented backfill of goafs provides one of the most effective pathways for their low-cost, green, and safe disposal. The research focuses on a multi-source solid waste uranium tailings backfill material. Through laboratory tests and theoretical analysis, the bleeding characteristics, flowability, and dynamic evolution of strength in the backfill slurry were systematically investigated. The leaching behavior of uranium and heavy metals from the backfill body was examined, and the hydration mechanism of the cementitious system was elucidated via microstructural analysis. The results show that the bleeding rate of the slurry initially decreases and then increases with an increasing sand-to-binder ratio. The flowability gradually decreases over time, with flow spread loss being more significant than slump loss. The strength of the backfill body decreases sharply with an increase in the sand-to-binder ratio, and the strength growth intervals vary notably among different sand-to-binder ratios, For a sand-to-binder ratio of 6, the main growth interval is before 28 d. For ratios of 6 and 8, this interval shifts to between 28 and 90 d. When the ratio increases to 15 or 20, the primary growth occurs before 7 d. The backfill body exhibits a high immobilization capacity for uranium and heavy metals, with leaching concentrations far below the relevant regulatory limits. The main hydration products in the backfill are gypsum, AFt, and C-S-H, whose morphology, quantity, properties, and distribution are closely related to its macroscopic strength. The research findings provide important theoretical insights for advancing the waste reduction of bulk industrial solid wastes such as uranium tailings.
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Optimization and Evaluation of Mining Methods for Steeply Inclined Thick Iron Orebodies: A Case Study of Mengku Iron Mine
Abstract:
The mining operation in the eastern section of the steeply inclined and thick orebody at Mengku Iron Mine of Xinjiang Jinbao Mining Co., Ltd. faces challenges such as poor ventilation circuit and insufficient roof stability. Systematic research on the optimization and selection of mining methods was conducted. Based on the analysis of orebody occurrence form and engineering geological conditions, three improved schemes were proposed: collaborative mining with upward and downward fan-shaped hole pair blasting, stage caving with large-diameter long holes, and fan-shaped hole pair blasting combined with flat-bottom extraction structure. An evaluation system covering 10 indicators, including production safety, ore loss rate, and ventilation conditions, was established using the correlation matrix method. Quantitative comparison and selection of the schemes were achieved through importance grading, weighting, and comprehensive scoring. The results show that Scheme 3 (fan-shaped hole pair blasting + flat-bottom structure) achieved the highest comprehensive score. While ensuring roof stability and ventilation safety, it reduced the ore loss rate to 7.8% and the dilution rate to 9.3%, achieving safe and efficient mining. This study provides technical basis and engineering reference for the selection of mining methods in the eastern section of Mengku Iron Mine and similar steeply inclined thick orebodies.
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Experimental Study on the Influence of Gangue Dip Angle on Coal Seam Stability Under Complex Geological Conditions
Abstract:
To investigate the influence of the dip angle of partings on coal seam stability under complex geological conditions, uniaxial compression tests were carried out on coal specimens containing partings with different dip angles in this study. Acoustic emission (AE) equipment and an optical digital image correlation (DIC) system were adopted to obtain the stress-strain curves, AE characteristic parameters and stress nephograms of the specimens with different parting dip angles. On this basis, the mechanical properties, AE characteristics and crack propagation laws of the specimens were analyzed systematically. The results show that the uniaxial compressive strength and elastic modulus of the specimens exhibit a decreasing trend with the increase of parting dip angle. The peak stress decreases from 14.79 MPa to 6.44 MPa, with a reduction amplitude of approximately 56%. The specimens with low parting dip angles present brittle failure, while the failure mode transforms to plastic failure for those with high dip angles. With the increase of parting dip angle, the elastic strain energy at the peak stress point of the specimens decreases gradually, and the difference in elastic strain energy between the specimens with a dip angle of 0° and 40° is nearly 2.6 times. The elastic strain energy stored inside the specimens is converted into dissipated energy through crack propagation, specimen deformation and other forms. The AE ringing counts of coal specimens with large-dip-angle partings are relatively higher, indicating that the development and connection degree of internal microcracks are more intense. As the parting dip angle increases, the cracks in the coal-rock composite body propagate gradually from the interface to the vertical direction, the slip displacement increases, and the complexity of crack development is enhanced. The proportion of tensile cracks in the coal-rock composite body increases slightly, and shear cracks are the dominant failure type. The research results can provide a certain reference for the study on the prevention and control of mine disasters under complex geological conditions.
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Mine Pressure Prediction Method Based on Multi-Feature Fusion Clustering and Spatiotemporal Modeling
Abstract:
Aiming at the problems of severe mine pressure fluctuations in fully mechanized mining faces under complex geological conditions, insufficient spatial continuity and ambiguous regional identification caused by the reliance of traditional incoming pressure criteria on a single index, a mine pressure prediction method based on multi-feature fusion clustering of support resistance curves and spatiotemporal perception modeling is proposed. On the basis of traditional incoming pressure indicators, multi-dimensional statistical features of support resistance curves are extracted. The k-means unsupervised clustering algorithm is adopted for adaptive division of supports with similar features, realizing the correction of incoming pressure discrimination results and intensity grading. An LSTM-Transformer combined prediction framework is constructed, and spatiotemporal attention (ST-Attention) and saliency attention (EP-Attention) are introduced to enhance the spatiotemporal representation capability of the model, achieving dynamic adjustment of attention weights. Experiments show that the model achieves the best prediction accuracy when the lookback window is 24 advancing cycles and the prediction step is 3 cycles, with MAE and RMSE values of 0.232 and 0.312 respectively. Ablation experiments indicate that the dual-attention mechanism exhibits a synergistic effect by jointly enhancing spatial coordination and transient-response amplification, with ST-Attention contributing most significantly to the improvement in prediction accuracy. Verification of predicted incoming pressure areas confirms that the method can accurately identify 4 incoming pressure events during the prediction phase of the actual mining face, with an accuracy rate of 91.85%. The research results provide a reliable technical approach for the intelligent prediction and precise identification of periodic incoming pressure in fully mechanized mining faces, and play a positive role in improving the intelligence level of safe and efficient coal mining.
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Application Research on Steeply Inclined Belt Conveyors in the Large-scale Deep Mining of Iron Ore Mines
Abstract:
To address the technical bottleneck that the traditional development methods of iron ore mines for deep-earth large-scale mining are insufficient to improve production capacity, this paper adopts the technical route of theoretical modeling - experimental verification - engineering application to systematically carry out research on the adaptability of steeply inclined belt conveyors in iron ore mines.
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The Impact of Dual Authority Leadership on Miners’ Counterproductive Behaviors
Abstract:
To reduce miners’ counterproductive behaviors and enhance the safety management standards in mining industry, this study draws on the situated focus theory of power, introducing sense of power as a mediating variable and growth need strength as a moderating variable. A moderated mediation model was established to examine how dual authority leadership influences miners’ counterproductive behaviors. The hypothesized model was tested using hierarchical regression analysis. The results indicate that: Dominance-focused authoritarian leadership positively influences miners’ counterproductive behaviors, whereas discipline-focused authoritarian leadership negatively influences them; Both dominance-focused authoritarian leadership and discipline-focused authoritarian leadership affect counterproductive behaviors through the mediating role of sense of power; Growth need strength positively moderates the relationships between dominance-focused authoritarian leadership, discipline-focused authoritarian leadership, and sense of power; Furthermore, growth need strength significantly moderates the mediating pathways through which dominance-focused authoritarian leadership and discipline-focused authoritarian leadership influence miners’ counterproductive behaviors via sense of power.The contributions of this study are mainly reflected in: revealing the differential effects of dual authoritarian leadership on counterproductive behaviors, explaining its internal mechanism from the perspective of sense of power, and identifying the boundary role of growth need strength, thereby providing new theoretical explanations and management insights for safety management in the mining industry.
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Research on optimizing the rotational speed and medium ratio of ball mill based on DEM
Abstract:
The primary ball mill discharge product of a certain lead-zinc ore suffers from an issue of excessively coarse particle size. To improve its particle size distribution and reduce the grinding load of subsequent processes, a research and analysis on the grinding parameters of the primary ball mill were carried out. In this experiment, the Discrete Element Method (DEM) simulation technology was adopted, taking a ball mill with a diameter of 3.6 m as the research object, to analyze the effects of different rotational speeds and different grinding media diameters on the grinding performance. The grinding performance of the ball mill was evaluated using three key indicators: particle behavior inside the mill, cumulative power spectrum, and collision frequency analysis. The results indicate that at a ball mill rotational speed of 17.3 r/min, the cumulative power exerted by steel balls on ore is higher, the particle motion state is more favorable, and the collision frequency is greater. The test results of grinding media diameter show that after adopting a recommended steel ball diameter ratio of 100 mm: 80 mm: 60 mm = 30: 45: 25, the particle size distribution of the ball mill discharge product has been significantly improved. The results of on-site investigation demonstrate that after optimization, the yield of the coarse particle fraction to be ground decreased by 5.74 percentage points, while the yield of the easily separable particle fraction increased by 4.78 percentage points.
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Dynamic Characteristics Analysis of Chain Drive Systems in Scraper Conveyors Under Different Operating Conditions
Abstract:
To investigate the mechanical characteristics of scraper conveyor chain links and sprockets under complex operating conditions, a coupled simulation method combining the Discrete Element Method (DEM) and Multi-Body Dynamics (MBD) was employed. Three operational scenarios—normal operation, chain jamming, and chain breakage—were simulated to examine the rigid-flexible coupling effects of the scraper conveyor under varying conditions. Results indicate: under normal operation, chain tension increases with rising chain speed and JKR, peaking at approximately 13 kN in condition LS34 (chain speed 1.0 m/s, JKR=20); The contact force between the scraper and sprockets generally exhibited an initial increase followed by a decrease. At a chain speed of 1.0 m/s, the maximum contact forces were observed between scraper 3 and sprockets 1 and 2, at 13.15 kN and 13.04 kN respectively. Chain speed exerted the most significant influence on the Y-axis vibration acceleration of chain links. During chain jamming, the contact forces on loaded link A and unloaded link B rapidly increased to 21.81 kN and 16.77 kN respectively, while the torque on the head and tail sprockets stabilised at approximately 28.25 kN·m and 25.80 kN·m. During chain breakage, a break on the loaded side caused the contact forces on links A and B to first increase then decrease, with link A eventually stabilising near 2 kN and link B dropping to zero. Concurrently, the head torque abruptly fell to 5.5 kN·m while the tail torque surged to 23.1 kN·m. A break on the unloaded side caused two abrupt drops in chain links A and B, which eventually stabilised within the ranges of 0.02–1.46 kN and 0.08–0.99 kN respectively. The head torque slowly decreased and fluctuated between 5.83 and 6.30 kN·m. Furthermore, chain-jamming condition tests were conducted using coal mine field data. The error rate between simulation and experimental values remained within 15%, further validating the accuracy of the MBD-DEM coupled simulation.
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Study on a Slope Stability Evaluation Method Based on the Integration of AHP and Improved D-S Evidence Theory
Abstract:
Slope stability is influenced by both randomness and fuzziness, and traditional deterministic approaches face challenges in integrating multi-source uncertainty. Although D–S evidence theory can address uncertainty, it is constrained by subjective basic probability assignment and failure under high-conflict evidence. This study proposes a slope stability evaluation method integrating AHP with improved D–S evidence theory. AHP is used to determine indicator weights; accordingly, three improved combination methods (Li, Huang, and Murphy) are introduced and compared with the classical D–S rule. A case study of an open-pit mine slope in Xinjiang with 12 evaluation indicators shows that all methods identify the slope as “stable.” Murphy’s method achieves the highest belief degree (0.78), consistent with radar monitoring results. The proposed approach demonstrates good rationality and engineering applicability.
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Research on optimization of backfill body ratio in a mine based on non-dominated sorting genetic algorithm
Abstract:
The ratio of filling body needs to meet the multiple objectives of stope stability, slurry fluidity and cost control at the same time. It is difficult for traditional experience selection to achieve global compromise optimization under the constraints of multiple indicators. Taking the cemented filling of a mine as the engineering background, this paper selects the reciprocal of cement-sand ratio and slurry concentration as decision variables, and establishes the response relationship between 28 d uniaxial compressive strength, slump and cementitious material cost. Based on the energy transfer and energy conservation before and after the recovery of the ore body, the energy matching coefficient of the surrounding rock and the filling body is introduced to construct the strength constraint, and the slump interval constraint and the upper limit constraint of the mine cost are set in combination with the literature and field conditions. On this basis, a three-objective optimization model with the maximum strength, the maximum collapse degree and the minimum cost is constructed, and the Pareto optimal solution set in the feasible region is obtained by NSGA-II. Combined with the applicability of the project, the cement-sand ratio of the filling body in the one-step stope is set to 1:10, and the concentration is 78%. The cement-sand ratio of the filling body in the two-step stope is set to 1:12, and the concentration is 77%. The monitoring results show that the maximum displacement is controlled within about 7 cm, which indicates that the optimized filling ratio can be applied in the mine site, and the cost of the cementing material is reduced by 30.89 %.
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Research on Landform Restoration of Metal Mines Based on Slope Design and Soil Reconstruction Technology
Abstract:
As the intensity of metal mining continues to increase, ecological damage problems such as slope instability and soil degradation have become increasingly prominent. In view of the shortcomings of traditional restoration technology, the study introduced the strength reduction method and combined the random field and Monte Carlo methods to optimize slope parameters. By applying functional microorganisms, modified minerals and three-dimensional pore structure directional reconstruction technology in layers, combined with the optimal soil ratio and phosphate passivation agent, an efficient soil reconstruction system was constructed. Finally, the two were integrated to form a mine landform restoration model with slope design-soil reconstruction synergy. Experiments show that the slope safety factor of the model proposed in the study reaches 1.32, which is 29.4% higher than traditional repair technology. The passivation rate of soil heavy metals lead and cadmium reaches 69.6% and 74.0% respectively, and the vegetation coverage rate is close to 100% within 12 months. The experimental results show that the mine landform restoration model proposed in the study solves the problem of mine landform damage from the root through the collaborative optimization of geological stability and ecological restoration, improves the stability and long-term effectiveness of the restoration effect, and has applicability and practical value in the ecological restoration of metal mines.
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Design and Practice of Ecological Restoration Project for Historical Abandoned Mines of Multiple Minerals
Abstract:
To address the prominent ecological damage in China"s historically abandoned mines and the insufficient pertinence and adaptability of existing restoration technologies, we have conducted ecological restoration engineering design and practical research, focusing on the differentiated damage characteristics of three types of patches: non-metallic mines, metallic mines, and mixed mines, using the historically abandoned mines in Lingbao City as the carrier. Following the concept that "mountains, rivers, forests, fields, lakes, grasslands, and sands are a community of life," we have constructed a composite governance model of "engineering reinforcement + ecological improvement + classified strategies." This model integrates technical measures such as terrain remediation, geological disaster prevention and control, soil improvement, and vegetation reconstruction, implementing precise governance according to the principle of "one patch, one strategy." The results show that after treatment, the project has fully completed the restoration of damaged land and eliminated geological disaster hazards; the vegetation coverage rate in the restoration area has significantly increased, with an annual reduction of 12,000 tons in soil erosion and an increase of 0.5 to 1.0 percentage points in soil organic matter content; it has achieved the comprehensive restoration goals of consolidating geological safety, improving ecological quality, and coordinating system functions. The constructed multi-mineral adaptive restoration technology system has verified the economic practicality of mixed planting of native vegetation and reuse of local resources, addressing the pain point of insufficient adaptability of traditional technologies. It can provide practical reference for the ecological restoration of historically abandoned mines in ecologically fragile areas in the north and similar mineral-rich areas.
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Research on the recovery process of low-grade iron tailings resources
Abstract:
In order to achieve effective recovery of iron resources from solid waste and alleviate the pressure of iron ore shortage, this study takes a low-grade iron tailings in Jingzhou, Hubei Province as the research object, and proposes a combined process of reverse flotation magnetization roasting magnetic separation to systematically recover weakly magnetic iron resources with complex forms of occurrence. Mineralogical analysis shows that the original ore has an iron content of 18.72%, mainly composed of weakly magnetic hematite (brown iron), with fine grain size and high vein content. In the reverse flotation stage, by optimizing reagents and regulating processes, pre enriched products with an iron grade of 43.60% and a recovery rate of 83.07% were obtained under suitable conditions, effectively removing silicate gangue. During the magnetization roasting stage, directional conversion of hematite to magnetite is achieved in a medium temperature reducing atmosphere. After weak magnetic separation, the final grade of iron concentrate is increased to 66.42%, with a comprehensive recovery rate of 88.67%. The results indicate that this combined process can achieve efficient recovery and enrichment of iron resources in tailings, providing a feasible technical path for the resource utilization of tailings.
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Study on the Impact Response and Energy Mechanism of Discontinuous Jointed Granite Under Different Confining Pressures
Abstract:
To investigate the effects of joint connectivity and joint segmentation on the dynamic response and energy distribution of granite under different confining pressures, numerical impact tests using the Split Hopkinson Pressure Bar (SHPB) method were conducted on granite specimens with four levels of joint connectivity and four levels of joint segmentation. The results indicate that an increase in joint connectivity significantly weakens the overall load-bearing capacity, showing an inverse relationship with the peak stress of the rock. Confining pressure suppresses joint opening and enhances joint surface friction, shifting the failure mode from tensile cracking to compressive–shear sliding. Additionally, the peak strain exhibits a U-shaped variation with increasing joint connectivity, and the corresponding inflection point appears earlier with higher confining pressure. Increasing the number of joint segments enhances the rock bridge effect, transforming the failure mode from single shear to complex interacti
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Study on the Bearing Function of Framework Mine Pillars in Ultra -Large Mines and Ground Pressure Control in Mining Areas
Abstract:
Ground pressure issues in ultra-large underground mines severely restrict the large-scale and safe exploitation of underground resources. Particularly under high-stress conditions, ground pressure problems become more prominent, which significantly increases the difficulty of large-scale mining. Therefore, effective ground pressure control is a prerequisite for the efficient and safe mining of ultra-large underground mines. Taking a large-scale backfill iron mine in China as the engineering background, a framed pillar structure for ground pressure control is proposed. A three-dimensional numerical model is established to analyze the load-bearing behavior of framed pillars in ultra-large underground mines under high-stress environments. Mining-induced response indexes between non-framed and framed pillar structures are compared, and the load-bearing mechanism of the framed pillar structure is investigated. On this basis, an integrated ground pressure control strategy is proposed, which combines upward mining in sections within isolation pillars, priority mining of stopes at both ends in framework units, and advanced pre-splitting and loose blasting on the hanging wall and footwall of stopes. The results show that, compared with the non-framed structure, the maximum bearing load of pillars, strata subsidence displacement, and surface movement monitoring range in the framed pillar model are reduced by 11.86%, 23.53%, and 22.06%, respectively. The framed pillar structure is conducive to enhancing the support effect on overlying strata and controlling the deformation of surface structures. The proposed ground pressure control scheme is favorable to the integrated ground pressure control of deep stopes, panels, and multiple mining sections.
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Mechanical Properties and Mix Proportion Optimization of Basalt-Polypropylene Fiber Concrete
Abstract:
Aiming at the defects of poor crack resistance and insufficient toughness of traditional concrete, this paper takes basalt-polypropylene double-doped fiber concrete as the research object. Through uniaxial compression test, Brazil splitting test and acoustic emission (AE) monitoring, the influence of fiber content on the mechanical properties of concrete is revealed, and the multi-objective optimization of fiber content is realized based on response surface method. The results show that the compressive strength and tensile strength of concrete increase first and then decrease with the increase of fiber content. When the volume content of basalt fiber (BF) is 0.2% + polypropylene fiber (PF) is 0.1%, the compressive strength is 44.68% higher than that of plain concrete. When BF 0.1% + PF 0.3%, the tensile strength increased by 34.65%. The cumulative AE count of acoustic emission decreased significantly with the optimization of fiber content. The cumulative AE count of the specimens with BF 0.1% + PF 0.1% was 51.82% lower than that of plain concrete, and the change of acoustic emission b value was highly consistent with the crack propagation stage. The quadratic regression model constructed by the response surface method has excellent fitting degree (compressive strength R2 = 0.9744, tensile strength R2 = 0.9774), and the optimal fiber content for engineering practice is BF 0.16% + PF 0.15%. The research results can provide a scientific basis for the ratio design and engineering application of high-performance fiber reinforced concrete.
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Research Progress and Countermeasures of Green Pretreatment Technology for Refractory Gold Ores
Abstract:
With the depletion of easily beneficiable gold resources, refractory gold has become the core raw material for gold production. The traditional roasting pretreatment process has serious environmental pollution problems, and green pretreatment technology has become an inevitable trend in the development of the industry. This article focuses on two core green pretreatment technologies, namely microbial oxidation and pressurized oxidation, and systematically reviews their reaction mechanisms, process characteristics, industrial application status and recent research progress. The focus is on analyzing the strain selection and breeding, the mechanism of synergistic action and the process enhancement technology of the microbial oxidation method. The reaction rules of the acid-base system and the equipment optimization direction of the pressurized oxidation method are expounded. By comparing with the traditional calcination process, the environmental and economic advantages of the green technology are highlighted. Based on the experimental data (referring to the latest research literature and making reasonable adjustments), verify the treatment effects of the two technologies. Finally, propose the key directions and countermeasures for future technological development, providing theoretical basis and technical reference for the green and efficient development of refractory gold mines.
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A Synergistic Approach for Zinc Removal from Blast Furnace Dust Using Sodium Carboxymethyl Starch: Selective Flocculation and Flotation
Abstract:
Flotation zinc removal, as a key technical path for the resource recovery and utilization of blast furnace dust, is of great significance for improving the utilization rate of resources. The pretreatment before grinding, while promoting the dissociation of zinc minerals, will also generate a large number of fine-grained minerals. The entrainment problem seriously restricts the selectivity of the flotation process. The problem of fine particle entrainment during flotation was addressed by flocculation. Pure minerals Fe2O3 and ZnS were selected as models to screen the types of flocculants. The effects of solution pH value and flocculant dosage on the flocculation effect were studied. The structural changes of flocs were investigated, and the verification of blast furnace dust flocculation flotation was carried out. The results show that zinc in blast furnace dust is enriched on the surface of iron particles, forming a zinc-iron interplay situation, and grinding leads to a high content of particles smaller than 10 μm. The sedimentation rate of hematite by sodium carboxymethyl starch (CMS) is much higher than that by sphalerite, demonstrating excellent flocculation selectivity. After the flocculation of hematite by CMS, larger flocs will be formed and the hydrophilicity will be enhanced. The flocculation process is greatly influenced by the pH of the solution. An alkaline solution environment is not conducive to the formation of hematite flocs. The addition of CMS significantly improved the recovery rate and selectivity of blast furnace dust flotation concentrate. The zinc grade of the concentrate increased from 8.5% to 13.5%, and the recovery rate rose from 19% to 50%.
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Systematic study on influencing factors of safety risks in metal mine mining based on Grey-DEMATEL-ISM-MICMAC
Abstract:
To precisely identify key influencing factors on underground metal mining safety and explore the inherent correlation between various influencing factors, based on literature induction and typical accident case analysis methods, 17 important influencing factors were identified from the perspectives of people, machinery, environment, management, and technology. The importance of these factors was analyzed using the Grey-DEMATEL method, and the multi-level hierarchical structure diagram of mining safety influencing factors was established using ISM to visually display the correlation between various influencing factors. The MICMAC method was used to conduct an in-depth analysis of the attribute characteristics of the factors, ultimately establishing an integrated analysis model of mining safety influencing factors based on Grey-DEMATEL-ISM-MICMAC. The results show that employee training and education, safety production management system, safety hazards investigation and management, and mining process rationality are key influencing factors of mining safety. The reliability of safety protection devices, routine equipment update and maintenance, environmental hazard source control, working environment conditions, key technology application, and technological innovation are direct influencing factors of mining safety. The research results can provide theoretical guidance for improving the level of mine safety management and theoretical support for mine safety assessment work.
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Determination of Rock Breakage Range and Cut Hole Distance in Single-Hole Blasting Based on D-P Criterion
Abstract:
In order to determine the hole distance of roadway excavation blasting more accurately and improve the penetration rate of roadway excavation, a calculation method of rock mass blasting failure range under the action of single hole blasting is proposed based on D-P（Drucker-Prager） criterion and rock blasting principle, and theoretical calculation and numerical simulation analysis are carried out based on the actual excavation and blasting engineering of an underground phosphate mine. The results show that the radius of the crushing zone is 56 mm, the radius of the crack zone is 206 mm and the radius of the crack propagation zone is 968 mm, which is very close to the finite element simulation results. According to the theoretical calculation and numerical simulation analysis, the parameters of cutting blasting in an underground phosphate mine are optimized. After optimization, the maximum utilization rate of gun hole is increased to 94.69%, and the average increase is 4.27%. The average blasting footage increased by 0.14 m, an increase of 4.67%; Explosive unit consumption is reduced by 0.16 kg/t, reducing 20.57%. The research results can provide reference for the vertical cut blasting parameters design of roadway excavation blasting, and have a good reference value for similar blasting projects.
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Study on Non-blasting Mechanized Mining Methods for Complex, Gently Dipping, Thick and Large Phosphorite Ore Bodies
Abstract:
The gently dipping thick phosphate ore body is generally characterized by “soft, fractured and weak” geotechnical conditions. Traditional metal mining methods face challenges such as difficult roof control, poor ore gravity flow, and severe blasting disturbance, making safe and efficient mining hard to achieve. Taking the Laohudong Phosphate Mine as the engineering background and based on the analysis of orebody occurrence and mining technical conditions, a zonal differentiated non?blasting mechanized mining scheme is proposed. The upper ore layer is mined using the dip?oriented longwall comprehensive mechanized mining method, with shearer for ore cutting, hydraulic powered support for roof control, and cemented phosphogypsum backfilling. The lower ore layer is mined using the pseudo?inclined long strip filling mining method, with roadheader?bolter miner for ore cutting, bolt?mesh support, and cemented phosphogypsum backfilling. The stope structural parameters, development and cutting layout, mining sequence, ventilation and backfilling systems are systematically designed, and the production capacity is calculated. The research indicates that the annual output of the fully mechanized mining face in the upper ore layer can reach 1.005 million tons, with loss rate and dilution rate both ≤5%; the annual output of the panel in the lower ore layer can reach 2.67 million tons, with loss rate and dilution rate ranging from 5% to 8%. This mining technology effectively reduces disturbance to the soft and fractured surrounding rock, ensures the stability of the gently dipping roof, solves the difficulty of ore transportation, and achieves safe, green and intensive mining of complex phosphate ore bodies. The research results provide a technical reference for the efficient mining of similar gently dipping thick phosphate ore bodies and fractured refractory ore bodies.
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Experimental Study on Precipitation Accumulation Behavior in Collapse Pits Under Glacial Moraine Cover of Pulang Copper Mine
Abstract:
Rainfall accumulation in the subsidence area of the Pulang Copper Mine constitutes a major source material for underground debris-flow accidents. A similarity-model experimental apparatus for rainfall accumulation in a collapse pit was developed to investigate the effects of rainfall intensity, rainfall duration, and the fine-particle content of moraine deposits on the ponding volume, infiltration depth, and moisture content in the pit. The results indicate that: (1) the ponding volume is positively correlated with rainfall intensity, rainfall duration, and moraine fine-particle content; furthermore, the effect of rainfall intensity becomes more significant with increasing rainfall duration, and the maximum ponding volume reaches 7895.13 cm3. (2) Higher rainfall intensity or longer rainfall duration increases the infiltration depth; however, as the moraine moisture content rises and gradually approaches saturation, the incremental increase in infiltration depth decreases. Seepage-induced migration of fine particles leads to the formation of a low-permeability barrier layer, which significantly inhibits the infiltration of ponded water. (3) High-intensity rainfall raises the maximum saturated moisture content in the pit to 67.06%. The effects of rainfall duration and fine-particle content on the moisture content are limited, but when the fine-particle content increases to 60%, a dense low-permeability layer forms and markedly delays the stabilization of moisture content. (4) A predictive model for rainfall-induced ponding volume in the collapse pit was established, with a fitting correlation coefficient of 0.976 and a mean error of 4.7%. These findings provide practical guidance for water-control measures in the Pulang subsidence area, help mitigate underground debris-flow risk, and support safe and efficient mine production.
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Analysis of the influence of tailings reservoir on the stability of mine engineering in a porcelain stone mine
Abstract:
The safety and stability of tailings ponds are crucial for ensuring the underground collaborative mining. To investigate the impact of tailings ponds on mine engineering, this study takes a certain lithium-containing kaolin mine as the research object, and uses the GTS/NX and FLAC3D coupling modeling method to establish a three-dimensional geological-structural model. It conducts optimization of the sealing length of the +225m horizontal shaft within the inundation line of the tailings pond and analyzes the influence of the tailings pond on the stability of the ore body mining. The results show that under different sealing lengths, the stress, displacement and plastic zone of the surrounding rock of the horizontal shaft change significantly. The optimal sealing length is 105 m, at which the tensile stress at the shaft opening drops to 0.20 MPa, the displacement deformation is 8 mm, and no plastic zone is generated in the sealing area, which can effectively control the water pressure of the tailings pond and ensure the stability of the horizontal shaft. By comparing the mechanical responses of ore body mining under the conditions with and without the tailings pond, it is found that the tensile stress of the roof of the mined-out area decreases from 0.87 MPa to 0.84 MPa, the displacement decreases from 15 mm to 14 mm, and the plastic zone of the mined-out area does not connect with the surface and the plastic zone of the tailings pond. Therefore, under the current engineering and geological conditions, the tailings pond is not the dominant factor for the stability of ore body mining. The research results can provide method references and data support for the collaborative safety design and assessment of tailings ponds and underground mining in similar mines.
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Research on the Fracture Evolution Process and AE Precursor Characteristics of Saturated Rocks with Initial Damage
Abstract:
To investigate the fracture evolution mechanism of water-permeable rock slopes in open-pit mines under blasting damage, before the experiment, the Hopkinson pressure bar experimental system was used to subject the biotite granulite from the eastern slope of Yanshan Iron Mine to impact, in order to prepare saturated rock samples with different initial damage. Subsequently, uniaxial compression test was performed on the rock specimens, with acoustic emission (AE) monitoring implemented to track the entire failure process in real time. The results indicate that as the initial damage degree increases, the AE event rates during the fracturing process of saturated biotite granulites transition from a temporal pattern of “low activity → short-lived surge → prompt stabilization” to that of “sustained ascent → concentrated peak → fluctuating decay”. Moreover, the initiation stage of high-energy crack events occurs progressively earlier with the increase of initial damage degree. The fracturing process transitions from an “ordered and stage-specific evolution” to a “disordered and synergistic co-evolution”, with a marked enhancement in the “multi-scale” cooperative co-evolution of cracks. Consequently, the macroscopic failure mode transitions from single shear failure to a mixed splitting-shear failure mode, accompanied by a notable increase in failure intensity. Considering the effect of initial damage degree, a multi-segment linear simplified model for the stress-strain relationship and a simplified fracturing precursor model based on AE parameters were developed for saturated biotite granulites. A dual early-warning indicator set for failure precursors, termed the “temporal precedence of the b-value and critical failure signaled by main frequency entropy” was proposed. The findings of this study thus serve as a theoretical and technical reference for elucidating the fracture evolution mechanisms and failure precursor early warning of water-rich rock slopes.
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A coal volume detection method for belt conveyors based on fusing lidar and vision image
Abstract:
Belt conveyors play a crucial role in continuous coal transportation in coal mining, and their efficient and accurate transportation is vital for intelligent coal mine production. However, factors such as the volume of coal and the running speed of the belt cause the real-time conveying capacity to change dynamically, posing challenges to precise regulation and hindering the development of intelligent coal mines. Traditional contact-type coal flow detection devices (such as electronic belt scales and nuclear belt scales) and existing non-contact detection technologies (such as monocular vision, binocular vision, ultrasonic, and line laser detection) all have numerous drawbacks and fail to meet practical demands. Therefore, this study proposes a coal volume detection method based on the fusion of camera vision and 128-line LiDAR point cloud data. By using the RGB-guided depth completion algorithm to achieve heterogeneous data fusion, the sensors are jointly calibrated to establish a mapping relationship and unify the coordinate system. Then, data is sampled through a specific strategy, and the coal volume area is identified using the Poisson reconstruction algorithm, spatial filtering strategy, and structural similarity index (SSIM). Finally, the depth image completion network is employed to repair the depth map, and the coal volume is calculated based on the repaired depth map. Experimental results show that the maximum error of coal volume detection by LiDAR is 4.70%, by visual camera is 7.22%, while the maximum error of the fusion method is only 2.9%, and the error further decreases as the volume of coal increases. Additionally, the detection curve of this method is basically consistent with that of the electronic belt scale, verifying its reliability. This method effectively overcomes the limitations of a single sensor, significantly improves detection accuracy, and can operate stably in harsh environments, providing a new technical solution for precise coal volume detection in belt conveyors and being of great significance for promoting intelligent and efficient coal mine production.
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Research on Dust Control Rule Acquisition in Intelligent Ventilation Systems for Fully-Mechanized Excavation Faces
Abstract:
Current local ventilation systems in fully-mechanized coal mine faces lack dynamic adjustment capability, leading to irrational airflow distribution, persistently high dust concentrations, and increased risks of dust explosion and pollution that seriously threaten workers' health. This study addresses these issues by investigating the acquisition of dust control rules for a self developed Intelligent Ventilation System. The work provides a theoretical basis for intelligent airflow regulation and dust suppression, and offers a technical reference for dust field optimization under different mine roadway and ventilation conditions. Using a fully mechanized face in northern Shaanxi as a case study, a gas solid coupled finite element model was established. Simulation schemes based on the Box Behnken principle were designed for different working conditions to obtain dust concentration data. With the average dust concentration at the return side pedestrian breathing zone and the dust concentration at the operator's position as dual objectives, an optimization model was constructed and solved using the MOEA/D algorithm. The optimal dust control rules obtained are as follows: for the left end cutting condition, the distance from the outlet to the working face L = 7.1 m, outlet diameter D = 0.9 m, and right deflection angle θ = 7.3 °; for the right end cutting condition, L = 6.9 m, D = 0.9 m, and θ = 14.2 °. Experimental validation showed a maximum relative error of 11.5 % between model predictions and measurements. After implementation, under the left end cutting condition, the average dust concentration at the pedestrian breathing zone and the concentration at the operator's position decreased by 49.9 % and 46.2 %, respectively; under the right end cutting condition, the corresponding reductions were 51.2 % and 72.8 %.
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Technical System and Empirical Research on the Effectiveness Assessment of Ecological Restoration for Open-Pit Mines in Hebei Province
Abstract:
To establish a scientific and systematic technical system for evaluating the ecological restoration effectiveness of open-pit mines and address the existing issues in current assessment work, such as scattered indicators, subjective methods, and insufficient dynamic monitoring, this study aims to provide support for precise management and scientific decision-making in regional mine ecological restoration. Taking Hebei Province as the research area, an evaluation indicator system was constructed, encompassing three criterion layers—ecological security, ecological function, and landscape effect—along with six specific indicators. By comprehensively employing the Analytic Hierarchy Process (AHP) and fuzzy mathematics theory, an AHP-fuzzy comprehensive evaluation model was established. Through the construction of judgment matrices and consistency tests (all CR values < 0.10), the objective weights of each indicator were determined, with vegetation recovery degree (weight 0.419) and plant diversity index (weight 0.173) being the most significant. An empirical study was conducted on the Beiducun Xishan limestone mine in Gaoyi County, Hebei Province. Using the fuzzy comprehensive evaluation method, the membership degree vector for each evaluation grade was calculated as (0.453, 0.353, 0.075, 0, 0.119). The results show that: 1) This technical system can effectively quantify restoration effectiveness. The comprehensive rating of the mine case is "excellent," primarily attributed to the high membership degrees of mine geological safety (0.7), soil erosion control (1.0), and landscape coordination (0.8). However, the membership degree of soil fertility recovery falls entirely into the "poor" grade, revealing the core issue of lagging soil restoration. 2) The model accurately identifies weak links in the restoration process, with the evaluation results highly consistent with on-site survey conditions. The technical system constructed in this study is systematic, operable, and applicable, enabling objective and quantitative assessment of the ecological restoration effectiveness of open-pit mines.
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Analysis of Mechanical Response and Fracture Characteristics of Fractured Granite Considering the Effects of Unloading Disturbances
Abstract:
To address the problem of damage and rupture of fractured rock mass induced by unloading stress field in deep excavation, granite specimens with fracture inclination θ=0°, 30°, 60°, 90° were prepared in this study, and uniaxial compression (UC), conventional triaxial compression (CT) and unloading test (TU) were systematically carried out to supplement the multi-inclination unloading model by combining with the discrete element simulation of PFC, so as to reveal the macroscopic and microscopic damage mechanism of the fractured rock mass under the high-stress unloading. It is shown that (1) The prefabricated fissures significantly deteriorate the specimen strength, but this effect decreases with increasing θ. Under UC conditions, for example, the strength of specimens with θ = 0° and 90° decreased by 56.9% and 8.4%, respectively, compared with the intact specimen (156.8 MPa). The fundamental reason is that the effective normal stress σ? for crack initiation decreases as θ increases. The fissured specimens exhibited marked sensitivity to unloading damage in TU tests, with higher?inclination specimens being more susceptible. (2) The geometry of the prefabricated fissures governs the crack initiation orientation and propagation path. All UC, CT, and TU tests showed deformation characteristics in which the peak radial strain (ε?) exceeded the peak axial strain (ε?). The unloading test (TU) was particularly notable: while its peak axial strain was similar to that in UC, its peak radial strain increased significantly. In addition, the proportion of shear cracks in the numerical model at the microscopic level was low (<10%). These three aspects jointly confirm the tensile?dominated failure mechanism of fissured specimens under unloading paths. (3) The fissure inclination θ controls the failure mode: low inclinations (θ ≤ 40°) exhibit composite wing?anti?wing crack failure; medium inclinations (θ = 50°–70°) transition to wing?crack?dominated shear failure; and high inclinations (θ ≥ 80°) evolve into mixed wing?crack and far?field crack failure. Moreover, the crack propagation path tends to concentrate toward the specimen ends as θ increases. Through full?inclination experiments and macro?micro?scale simulations, this study quantifies the coupling effect between fissure geometry and unloading paths, providing a theoretical basis for the prevention and control of unloading?induced disasters in deep engineering fractured rock masses.
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Study on the Combined Impurity Removal and Purification Process of High-carbon and High-calcium Bismuth Medium Ore Reagent Removal, Bismuth Floating and Acid Leaching
Abstract:
In order to efficiently develop and utilize refractory bismuth-containing polymetallic ores and realize the comprehensive recovery of bismuth resources, aiming at the bismuth recovery problems of high-carbon and high-calcium bismuth middle ore with strong interference of high-carbon and high-calcium gangue, complex pulp environment and front-end chemical inhibition, a combined impurity removal and purification process of "activated carbon reagent removal pretreatment-flotation bismuth extraction-acid leaching purification" was innovatively proposed, and systematic process mineralogy and bismuth recovery experiment were carried out to systematically optimize the process parameters. The results showed that the bismuth concentrate with high carbon and high calcium was extracted by hydrochloric acid and activated carbon slurry with reagent removal, water glass + lime as inhibitor, butyl xanthate as collector and No.2 oil as foaming agent, and 18% mass concentration hydrochloric acid was leached for 8 minutes at 30 ℃ and liquid-solid ratio 2:1. The yield of bismuth concentrate was 17.07%, bismuth grade was 19.91% , and the recovery rate of bismuth was 74.75%. This process targeted to solve the key technical bottleneck of high-carbon and high-calcium bismuth middle ore recovery. It accurately eliminates the inhibitory effect of chemicals through activated carbon dechemication pretreatment, and then uses flotation process to achieve efficient separation and enrichment of bismuth minerals and gangue minerals such as calcium carbonate. Finally, the selective removal of residual impurities is achieved through acid leaching to ensure the upgrading effect of bismuth concentrate and achieve effective impurity removal and purification of high-calcium and high-carbon bismuth middle ore.
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Research on the determination of waterproof rock pillars and safe mining technology for the extraction of ore bodies under pressure from a river in an iron mine
Abstract:
Addressing the risk of water-conducting fracture breakthrough during mining of ore bodies under river pressure, and taking into account the engineering geological conditions of the mining area and modern backfill mining technology, the "three zones" theory was employed to determine the safe thickness of the roof-supporting rock pillar. Numerical simulation techniques were utilized to evaluate the impact of mining from the perspectives of displacement field, stress field, and plastic zone distribution, thereby verifying the reliability of the waterproof roof-supporting pillar design. The results indicate that when mining the ore body below 120 meters using the upward layered backfill mining method, a waterproof rock pillar with a thickness of 69 meters is required. The inclination deformation, horizontal deformation, and curvature caused by the excavation of the Mahe River bed are all within the allowable range for surface building deformation, and will not affect the impermeable layer at the bottom of the Mahe River. Therefore, mining the ore body under the Mahe River is safe and reliable. The amount of resources released from this mining operation is approximately 3.61 million tons, with potential economic value ranging from 1.79 to 2.19 billion yuan. This is of great significance for enterprises to scientifically develop resources and achieve sustainable development.
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Comparative Study of Individual and Combined Beneficiation Methods for a Gold-Silver Ore in the Nenjiang-Heihe Mélange Belt
Abstract:
Beneficiation test research was conducted on a gold-silver ore from the Nenjiang-Heihe mélange belt. The ore characteristics were investigated using advanced analytical techniques, including the Mineral Liberation Analyzer (MLA), electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and chemical analysis.The analysis revealed that the raw ore contains 1.80 g/t Au and 98 g/t Ag. Gold distribution in pyrite reaches 91.38%, while silver distribution is 35.61%. The particle size of pyrite varies significantly, whereas argentite (Ag?S) particles are almost entirely below 75 μm.The run-of-mine (ROM) ore was processed through a combined flotation-tailings leaching test circuit, yielding overall recoveries of 96.76% Au and 93.10% Ag.Gravity-flotation combined process for gold recovery represents an eco-efficient beneficiation technology, achieving economic viability while ensuring environmental protection.
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Study on the Rheological Evolution and Application of Cement Slurry Backfill Materials under the Time-Dependent Effect of Cement Hydration
Abstract:
In this study, the abrupt change law of the yield stress of cementitious filling slurry at the key node of 40 minutes (growth rate of 30.3%) was revealed through the systematic rheological test under constant temperature conditions of 25°C. After analysis, with the increase of hydration time, the formation of excessive hydration products will cause particle agglomeration and microstructure compaction, resulting in an increase in the apparent viscosity of the slurry, and a significant increase in pipeline friction. Based on this finding, the modified Darcy-Weissbach equation is derived, and the design method of "time-varying rheology-segmented resistance" filling pipeline is innovatively proposed, which is verified by the design of 5km filling pipeline engineering case, which reduces the pumping pressure by 22.2% and saves the investment cost of the filling pipeline by 23.7% compared with the traditional scheme.
Keywords: long-distance conveying; rheological evolution; pipe resistance; segmented design;- 1
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Hydrogeochemical Characteristics and Source Identification of a Gold Mine in Hunan, China
Abstract:
Abstract: Water-related hazards are a major constraint in metal mining, and understanding the sources, recharge pathways, and hydrochemical evolution of mine inflows is crucial for safe operations. A gold mine in Hunan Province was selected as the study area, through the collection and analysis of surface water, groundwater, and mine inflow samples. Hydrochemical characteristics were evaluated using Piper diagrams, ion ratio analysis, and multivariate statistical methods. The results indicate that the regional water is predominantly HCO?-Ca type, with Ca2+ and Mg2+ as dominant cations and HCO3- and SO?2? as major anions. Mine inflows are located in areas of high HCO3-/Cl? and low Sr2+/Ca2+ ratios, suggesting short residence times and intensive carbonate dissolution along fracture zones or goaf pathways. Principal component analysis (PCA) reveals that the first principal component (PC1), accounting for 51.037 % of the variance, is strongly associated with TDS, EC, HCO3-, Mg2+, Ca2+, and SO42-, reflecting the dominant influence of carbonate rock–water interaction and mineralization. Hierarchical cluster analysis (HCA) classified the water bodies in the study area into three groups according to their degree of correlation with mine inflow: a strongly correlated group (a), a moderately to weakly correlated group (b), and a weakly correlated anomalous group (c). Based on an integrated analysis, the hydrochemical evolution characteristics of the water bodies and the features of underground mine inflow were systematically identified, providing a scientific basis for mine water hazard prevention and safe mining operations. Key words: gold mine, Piper diagrams, ion ratio analysis, multivariate statistical methods
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Research on Optimization of Stope Structural Parameters and Mining Sequence Based on Numerical Simulation for the Sublevel Open Stoping Method
Abstract:
Aiming at the key issues of stope structural parameter optimization and stoping sequence optimization in the sublevel open stoping method, this study takes a certain mine as the engineering background. By integrating engineering geological analysis, mining theory, and numerical simulation technology, four stope width × pillar width schemes (15 m×10 m, 12 m×10 m, 15 m×12 m, and 12 m×12 m) are designed. The evolution laws of the surrounding rock displacement field and stress field are analyzed through multi-dimensional comparison.Based on the analysis of the geological conditions in the mining area, the sublevel drilling sublevel open stoping method is determined as the core mining method, and the stoping principles of "top-down between levels and far-to-near within a level" are clarified. Rock mass mechanical parameters are reduced through field investigation and theoretical analysis, and a three-dimensional numerical model is established to simulate the sequential stoping process of four levels from +300 m to +150 m.The results show that stope width and pillar width have a significant synergistic effect on stability. For Scheme 4 (12 m×12 m), the roof subsidence is 1.7 mm, the floor heave is 4.1 mm, and the maximum tensile stress is 0.90 MPa, indicating the optimal stability. The production capacity of the test stope is 350 t· d-1, the ore loss rate is 25%, and the ore dilution rate is 5%, which verifies the effectiveness and safety of the stoping sequence. This study provides theoretical and practical support for the safe and efficient mining of mines with similar geological conditions.
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Reasonable Span Determination and Stability Evaluation of Overhand Horizontal Cut-and-Fill Stopes
Abstract:
To optimize stope structural parameters under the safety constraints of overlying buildings/structures and farmland, this study takes an iron mine employing overhand horizontal cut-and-fill mining as the engineering background and proposes a stope span selection method based on a “allowable-span theoretical criterion–3D numerical simulation–multi-index comprehensive evaluation–engineering recommendation” workflow. First, the allowable roof span is determined using a simply supported beam criterion, in which the mechanical parameters of the roof rock beam are reduced according to laboratory rock mechanics test results to obtain the theoretical ultimate span. A numerical model that distinguishes between hanging-wall, orebody and footwall lithologies is then established to compare three span schemes of 8, 10 and 12 m. A composite stability evaluation index system is constructed using the maximum unbalanced force, principal stress fields, vertical (Z-direction) settlement displacement and the volume fraction of plastic zones. The results show that both the peak unbalanced force and the extent of the plastic zone increase markedly with span, and the stope with a 12 m span approaches or even exceeds the self-stability limit of the rock mass under multiple operating conditions. In contrast, tensile failure in the roof and floor and shear failure along the sidewalls in the 8 m span scheme are mainly confined to local areas, and the overall deformation remains controllable. Considering both safety and engineering feasibility, an 8 m span is recommended for the overhand cut-and-fill stopes in this mine. The proposed method and results provide a quantitative basis and engineering reference for span design and stability evaluation of similar overhand horizontal cut-and-fill stopes.
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Ground Stability Study of Building-Sensitive Areas Using FLAC3D and a Multi-Index Evaluation Model
Abstract:
Ground subsidence induced by underground mining can easily pose safety threats to surface structures such as building-sensitive zones, and this problem has become a key technical challenge in mining engineering. Taking a metal mine as an engineering case, this paper combines Rhino modelling with FLAC3D numerical simulation to construct a 3D orebody–surface model, and simulates the backfilling and stoping process in four stages to obtain ground displacement contour maps and displacement data along the NE and NW monitoring lines at different stages. On this basis, the vertical settlement w, horizontal strain ε, tilt i and curvature k at selected monitoring points are used to develop a multi-index intelligent evaluation model for ground stability, and a genetic algorithm is employed to determine the weights of each index. The results show that ground settlement exhibits an evolution pattern of “slow at the early stage and accelerated at the middle and late stages” as mining progresses, with the maximum vertical settlement increasing from 11.1 mm to 179.7 mm; the peak horizontal displacement in the x-direction, 74.8 mm, is greater than the 59.1 mm in the y-direction, with high-value zones concentrated above the goaf. After weight inversion using the genetic algorithm, the intelligent evaluation model yields a weight vector of ww=0.1001、wε=0.2411、wi=0.1596 and wk=0.4993. Substituting the measured data, the comprehensive index Sp at the control points of all buildings ranges from 0.102 to 0.150, which is lower than the stability threshold of 0.3 and corresponds to a stable ground condition. The study confirms that the mining method, selected backfill strength and protective pillar configuration of this mine are reasonable and can satisfy the safety requirements of buildings and surface facilities.
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Strength Evolution and Micro-Mechanisms of Biopolymer-Amended Open-Cast Mine Dumps under Freeze–Thaw Conditions
Abstract:
As a typical man-made geomaterial in large-scale open-pit mines, waste dumps consist of loose and water-sensitive surface soils that are highly vulnerable to softening, disintegration, and strength degradation under rainfall infiltration, loading disturbances, and repeated freeze–thaw cycles. Such degradation severely threatens dump-slope stability and ecological rehabilitation. To enhance the engineering adaptability of dump cover soils, this study investigates the effects of xanthan gum (XG)—a green biopolymer—on the mechanical behavior and freeze–thaw durability of weathered residual soils derived from sedimentary rocks. A series of laboratory tests, including Atterberg limits, unconfined compressive strength (UCS), consolidated–undrained (CU) triaxial tests, and freeze–thaw cycling, were conducted, accompanied by SEM microstructural analysis. Results demonstrate that an appropriate XG content (2%) substantially improves the plasticity, UCS, and cohesion of dump soils, with UCS increasing by approximately 2.2 times and cohesion by more than 140% compared with untreated soil. After eight freeze–thaw cycles, the 2% XG-modified soil retained 66.4% of its initial strength, significantly outperforming the untreated soil (54.6%). SEM observations revealed that XG forms adhesive films and bridging networks on soil particles, fills pores, enhances interparticle bonding, and suppresses freeze-induced microcrack propagation; excessive XG (4%) leads to oversaturation and structural softening. This study demonstrates that xanthan gum effectively enhances the mechanical properties and freeze–thaw resistance of waste-dump cover soils, providing a scientific basis and technical reference for green stabilization, cover-soil improvement, and ecological restoration in open-pit mining areas.
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Vegetation Cover Change Monitoring and Ecological Restoration in Mining Areas based on Remote Sensing Images
Abstract:
Mining activities have a significant impact on the ecological environment. Traditional vegetation monitoring methods are limited and cannot meet the practical needs of ecological restoration in mining areas. Therefore, this study, focusing on the Fushun West Open-pit Mine in Liaoning Province, established a multi-temporal remote sensing imagery vegetation cover change monitoring system and a corresponding ecological restoration effectiveness evaluation method. This study employed an improved pixel binary model to establish a hierarchical vegetation cover inversion algorithm, constructing a three-layered composite change monitoring system. Furthermore, differentiated ecological restoration strategies were developed based on site conditions, and a restoration trajectory index and Logistic prediction model were proposed for dynamic trajectory analysis. Results showed that the proposed method achieved a vegetation cover monitoring accuracy of 94.2%. The vegetation cover in the deep soil area on gentle slopes increased to 0.68 within five years, and the community stability index reached 90% of that of the natural reference community. This study provides a scientific vegetation monitoring and ecological restoration technology solution for large-scale open-pit mining areas, which is of great significance for promoting sustainable development in the mining industry and promoting ecological civilization.
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Review and Development Prospects of Deep Mining Technology for Metal Mines
Abstract:
With the depletion of shallow metal mineral resources, advancing into deep mining has become an inevitable strategic choice to ensure national resource security. However, the complex geomechanical environment characterized by "three highs and one disturbance" (high in-situ stress, high temperature, high karst water pressure, and mining disturbance) poses severe challenges to traditional mining methods in terms of safety, cost control, and operational efficiency. By reviewing typical engineering practices of domestic and international deep mines and recent scientific research achievements, this paper systematically summarizes the development status, key engineering technical difficulties, and main technological paths of deep metal mining. It analyzes the applicability and limitations of deep mining methods under different occurrence conditions and points out that "large-scale mining, intelligent equipment, and continuous operation" are the core directions for the technological transformation of deep mining. Targeting three typical ore body occurrence conditions—deep thick and stable ore bodies, fractured ore bodies, and thin veins—this paper proposes process technology systems centered on high-stress coupled rock breaking and modular continuous mining, environmental reconstruction and pressure-relief mining, and refined blasting and waste-free efficient mining, respectively. Meanwhile, it analyzes the application potential of non-explosive mechanized continuous mining technology in reducing disturbances and improving intrinsic safety levels. Relevant engineering practices indicate that the aforementioned technological paths have significant effects in improving mining efficiency, reducing production costs, minimizing blasting disturbances, and increasing resource recovery rates. The study aims to provide theoretical basis and technical paths for the transition of China's deep metal mining from traditional modes to intelligent and continuous technology systems, helping to form new quality productive forces in the development of metal mineral resources
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Research and Analysis of Statistical Damage Model for Sandstone Based on Triaxial CT Testing
Abstract:
Investigating the deformation and failure evolution of rocks under different loading conditions is of great significance for revealing rock failure mechanisms. Due to the inherent heterogeneity of rock materials and the randomness of micro-damage development, establishing a damage model capable of describing the entire deformation process is essential for a comprehensive understanding of rock mechanical behavior, particularly for rock engineering subjected to post-peak stress states. In this study, triaxial compression tests and X-ray computed tomography (CT) scanning tests under triaxial loading conditions were conducted on sandstone specimens to obtain complete stress–strain responses and damage evolution processes under different confining pressures. Assuming that the rock damage variable follows a Weibull distribution, statistical damage constitutive models (SDCMs) based on strength distribution and volumetric strain distribution were established, and the evolution characteristics of the damage variable were analyzed. Furthermore, numerical simulations were performed to investigate the damage mechanisms reflected by the models from the perspectives of microcrack evolution and energy dissipation. The results indicate that the damage evolution of sandstone in the post-peak softening stage is closely related to the non-uniform expansion of volumetric strain, and the energy dissipation accompanying microcrack propagation drives the continuous growth of volumetric strain after peak stress. Compared with the traditional SDCM based on strength distribution, the SDCM based on volumetric strain distribution can effectively simulate the continuous accumulation of damage and provides a more accurate characterization of damage evolution, especially under high confining pressure conditions. The findings of this study provide a theoretical basis for the rational characterization of post-peak mechanical behavior of rocks and the stability analysis of rock engineering.
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Analytical Calculation of Traction Torque and Optimal Design of Grouser Structure for Deep-sea Mining Vehicles
Abstract:
Aiming to address the issues of insufficient traction force and significant torque fluctuation in tracked mining vehicles operating on deep-sea soft and weak sediments, which result in slippage and poor driving stability, and to achieve coordinated optimization of traction performance and travel smoothness, an optimization design of grouser structural parameters is carried out. Comprehensively considering the grouser structure of the deep-sea mining vehicle and the deep-sea seabed soil conditions, a transient excitation analytical model for the grouser-soil interaction is established based on the modified Rankine passive earth pressure theory. By characterizing the dynamic contact process between the track and the seabed, the analytical expression for the dynamic traction excitation of the track is derived. Subsequently, a track?soil coupled dynamic model is developed using RecurDyn, and its rationality is verified by comparing the results with the analytical values of the dynamic traction excitation. Furthermore, the influence patterns of key grouser structural parameters on traction performance are analyzed. An optimization framework integrating the analytical model and the NSGA-II algorithm is constructed, with the mean traction torque and the peak-to-peak torque fluctuation as the objective functions, to achieve the collaborative design of the grouser structure. The results show that the traction torque analytical model agrees well with the simulation results, verifying the rationality of the analytical calculation model for the traction torque of the deep-sea mining vehicle. After optimization, the average traction torque of the grouser structure increases by 3.1%, and the peak-to-peak value decreases by 48.8%, effectively enhancing travel stability while meeting traction performance requirements. This research provides technical support for the optimized design of the tracked traveling mechanism of deep-sea mining vehicles.
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Research on the Comprehensive Recovery of a Low Grade Co- associated Mixed Tungsten Ore and Fluorite Resource
Abstract:
In the flotation tailings of a skarn-type copper polymetallic deposit in southeastern Yunnan, the grades of WO3 and CaF2 were 0.26% and 32.60%, respectively. The gangue minerals were primarily SiO2 and CaCO3, with contents of 35.12% and 7.19%, while the harmful element S content was 0.86%. Tungsten mainly existed in the forms of scheelite, wolframite, and tungstite, accounting for 85.39%, 11.15%, and 3.46%, respectively, belonging to low-grade associated mixed-type tungsten-fluorite resource. The liberation degree of both wolframite and fluorite in the flotation tailings exceeded 94%. To comprehensively utilize the tungsten and fluorite resources in this tailings, systematic beneficiation tests were conducted. The process employed included room-temperature mixed flotation of scheelite and wolframite, heating flotation of tungsten rough concentrate, and fluorite flotation. For the room-temperature mixed flotation, Na2CO3 served as the medium adjuster, Na2SiO3 as the depressant, and the mixed collector GYX for scheelite and wolframite.In the heating flotation, NaOH was used as the medium regulator and Na2SiO3 as the depressant, with heating flotation performed after 60 minutes of stirring at 90°C. For fluorite flotation, modified oleic acid GY4 was used as the fluorite collector, and acidified Na2SiO3 as the regulator. Closed-circuit laboratory tests yielded a tungsten concentrate with a WO3 grade of 62.17%, WO3 recovery of 81.30%, and CaF2 content of 3.67%, as well as a fluorite concentrate with a CaF2 grade of 96.13%, CaF2 recovery of 89.47%, and WO3 content of 0.06%. Both tungsten and fluorite were effectively recovered, providing technical support for the development and utilization of this low-grade associated mixed-type tungsten-fluorite resource.
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Study on Collaborative Optimization and Performance of Multi-Source Coal-Based Solid Waste Composite Filling Materials
Abstract:
In view of the technical problems of large cement consumption, low mechanical strength, and poor durability of a phosphate rock filling material in Hubei Province, coal-based solid waste was selected to replace cement to prepare new cementitious materials. Based on the comprehensive method test, the effect of coal-based solid waste content and specific surface area on the performance of backfill was investigated. The results show that the slump of slurry decreases with the increase of coal-based solid waste content and specific surface area, while the plastic viscosity and yield stress increase approximately linearly. The compressive strength of the backfill increases first and then decreases with the change of the two. The best mechanical properties are obtained when the content is 40 % and the specific surface area is 440 m2/kg. The compressive strength of 3, 7, 14, 28, 90, and 270 days is 1.89, 2.38, 2.65, 3.46, 3.93, and 3.12 MPa, respectively. In addition, the shrinkage of the backfill increases with the increase of the content, and the appropriate amount of fine particles can promote hydration, while the excessive amount will deteriorate the pore structure, increase the capillary tension, and aggravate the shrinkage. The industrial test confirmed that the error between the strength of the backfill on site and the laboratory results was less than 7 %, which verified the engineering applicability of the ratio.
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Research on the Flow Characteristics of Multi-stage Coarse Aggregate Filled Slurry and the Strength of the Filling Body
Abstract:
In order to explore the relationship between the particle size gradation of waste rock and the flow characteristics of filling slurry and the strength of filling body, the waste rock of a mine was screened into different particle sizes. The slump test of filling slurry with different particle size gradation and the strength ratio test of filling body were carried out by response surface analysis method. The effects of different particle size gradation, cement-sand ratio, mass concentration and their interaction on the flow characteristics of filling slurry and the strength of filling body were analyzed. The results show that : 1 ) The waste rock particles with different particle size gradations are coarse, and the content of cement-20 μm can reach 48 %. Adding a certain amount of cement to the filling slurry can improve the flow state of the slurry and meet the requirements of long-distance pipeline transportation. 2 ) Based on the response surface analysis method, the regression models of backfill strength and slurry slump were established. The fitting degrees of the two were 0.931 and 0.927, respectively. The model had high fitting degree and strong reliability. 3 ) Under the single factor, the degree of influence on the slump of the filling slurry from large to small is the cement-sand ratio, the particle size distribution of the waste rock, and the mass concentration, and the degree of influence on the strength of the filling body from large to small is the mass concentration, the particle size distribution of the waste rock, and the cement-sand ratio ; under the multi-factor coupling interaction, the degree of influence on the slump of the filling slurry from large to small is the interaction between the particle size gradation of waste rock and the mass concentration, the interaction between the particle size gradation of waste rock and the cement-sand ratio, and the interaction between the mass concentration and the cement-sand ratio. The degree of influence on the strength of the filling body from large to small is the interaction between the mass concentration and the cement-sand ratio, the interaction between the particle size gradation of waste rock and the mass concentration, the interaction between the particle size gradation of waste rock and the cement-sand ratio. 4 ) The optimized filling parameters of a mine are as follows : the particle size distribution of waste rock is-5mm, the mass concentration is 82 %, the cement-sand ratio is 1 : 9.6, and the error between the predicted value and the actual value of the slump of filling slurry and the strength of filling body is less than 5%. It can be verified that the response surface analysis method is reliable for optimizing the strength of filling body and the slump of filling slurry. The research results can provide technical support for the design and construction of the later filling system of the mine.
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Study on the Mechanical Properties and Microscopic Mechanism of Basalt Fiber Reinforced Phosphogypsum-Based Backfill MaterialCHAO Liang 1, ZHAO Bing 1 , LAN Rong 2, LIU Mingsheng 2
Abstract:
To achieve the resource utilization and efficient application of mine solid waste, an experimental study was conducted using phosphogypsum-based consolidated material as a cementing agent and basalt fiber as the reinforcement phase. The synergistic effects of fiber parameters (length and content) and the gradation index of waste rock on the mechanical properties and microstructure of backfill materials were systematically investigated. The experimental results indicate that the compressive strength of the backfill materials initially increases and then decreases with the increase of each factor level. Through orthogonal experiments and range-variance analysis, it is determined that fiber content is the dominant factor influencing strength, with the optimal mix proportion being a fiber length of 9 mm and a content of 0.3%. The incorporation of fibers effectively enhances strength and toughness, inhibits the propagation of macroscopic cracks, significantly improves the mechanical properties of the material, and promotes a transition from brittle to ductile failure. Microscopic analysis reveals that basalt fibers form stable interfacial bonds with silicate gels through surface active groups, effectively delaying the initiation and propagation of microcracks. The fiber reinforcement technology substantially extends the service life of the material in harsh mining environments, meeting practical engineering requirements.
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Optimization of structural parameters and stability study of deep inclined thick and large ore body quarries
Abstract:
To address the challenge of stability control in inclined, thick ore bodies under deep mining conditions, this study employs a segmented stoping with subsequent backfilling mining method at a lead-zinc mine as its engineering context. Integrating the Mathews stability diagram method, Laubscher graphical method, and Q classification system, a multi-method coupled assessment system is proposed. Numerical simulation validation is conducted using Rhino-FLAC3D coupled modeling. Results indicate: the hydraulic radius for stable roof conditions is 2.78 m, for side walls 4.63 m, and for floor/roof 5.00 m; the maximum safe span without support is 7.17 m. Comparing 12 m and 14 m bench heights via numerical simulation reveals the 12 m scheme significantly reduces roof displacement (24.1 mm) and yields more controllable plastic zone distribution. The recommended approach involves adopting a 12 m bench height, a longwall length of ≤20 m, and a span of 7 m. Layout configurations should be flexibly selected based on ore body thickness (≤7 m or >7 m), providing an optimized solution for safe deep mining operations.
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Study on optimization of charge structure based on dynamic response of slope blasting with weak interlayer
Abstract:
The dynamic response mechanism of slope rock mass with weak interlayer under blasting dynamic action is significantly different from that of homogeneous rock mass, which often leads to high risk of instability and poor crushing effect. To solve this engineering problem, a limestone mine with weak interlayer was taken as the research object. The PFC particle flow code suitable for simulating crack propagation and block separation was used for numerical simulation, and the optimization of charge structure was carried out in combination with field test. Based on the actual parameters of the site, the rock mass model of the slope with weak interlayer is constructed, and the dynamic response characteristics of the slope under the existing continuous charge are summarized. The crack propagation, peak vibration velocity and displacement variation of the five interval charge schemes are compared and analyzed and verified by field tests. The results show that the charge structure with 6 m bottom charge, 2 m middle interval and 3.5 m upper charge can effectively inhibit the concentrated propagation of cracks to weak interlayers. Compared with the continuous charge structure, the peak vibration velocity of the slope is reduced by about 30 %, the single hole charge is reduced to 88 kg, and the blasting pile is uniform without bulk. The research results reveal the double influence of weak interlayers as vibration guided wave layer and crack propagation on slope stability and provide theoretical basis and practical reference for the fine blasting design of similar mines.
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Study on the characteristics and control technology of ground pressure in multi-panel continuous mining of solid potash mine
Abstract:
To investigate the ground pressure manifestation characteristics and determine the optimal mining mode during multi-panel continuous mining in solid potash mines. Based on disturbance control theory, this study established a mining sequence optimization scheme. Using FLAC3D software, a 3D geomechanical model of a solid potash mine was constructed to simulate and compare the stress redistribution laws and deformation evolution characteristics under three mining sequences: opposing advance, central-wing, and hybrid modes. The results indicate that both the central-wing and hybrid schemes exhibit abrupt "steep rise–steep drop" transitions in stress during the middle stage of mining. In contrast, the opposing advance scheme shows a relatively gentle stress fluctuation amplitude. By optimizing the mining timing and staggering critical disturbance events, the stress superposition effect between adjacent panels is effectively reduced. Specifically, in the hybrid mining mode, the stress concentration induced during the central-wing phase is more pronounced, which tends to intensify local stress redistribution and concentration in the surrounding rock. Although surface subsidence is substantially similar across all three schemes, the opposing advance scheme results in smaller roof subsidence and milder stress fluctuations. Therefore, the opposing advance sequence is recommended as the optimal mining order for multi-panel continuous mining in solid potash deposits. These findings provide key technical support for coordinated multi-panel mining.
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Stability Analysis and Layout Optimization of Stratified Phosphorite Stopes Based on Multi-Method Coupling
Abstract:
With the underground mining depth of the Kunyang Phosphate Mine No. 2 approaching 300m, localized roof collapse accidents have occurred frequently, severely affecting both safety production and ore recovery efficiency. To address the challenge of roof stability control in the stopes of this layered phosphate deposit, a multi-method coupled research framework integrating theoretical analysis, empirical assessment, and numerical simulation has been established. A calculation model for the critical roof span, considering water-induced weakening effects, was developed based on beam-slab theory. The results indicate that under humid and unsupported conditions, the allowable spans for the immediate roof dolomite and the indirect roof black shale are 3.2m and 4.9m, respectively. Stability probability assessment using the modified Mathews stability graph method revealed that the stope width should be limited to within 5m to maintain a roof stability probability exceeding 80%. FLAC3D numerical simulations comparing the strike-oriented layout and the dip-oriented layout showed that the strike-oriented arrangement reduces roof displacement by 48.8% and significantly improves the roof stress state. Integrating the above analyses, the final standard stope cross-section was determined to be 5m × 5m, employing the strike-oriented layout. The research findings provide crucial technical support for the safe and efficient mining of this phosphate mine and offer a systematic research methodology for stability control in similar layered deposits.
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Study on the Overall Efficiency Model of Gear Pumps in Deep-Sea Environments and Its Influencing Factors
Abstract:
Seawater hydraulic systems possess the capability of adaptive sea depth adjustment and utilize seawater as the working medium, thus being widely applied in marine environments. However, the characteristics of low temperature and high pressure in deep-sea environments can lead to changes in the properties of hydraulic media and the efficiency of gear pumps. Therefore, taking a certain type of drilling rig gear pump as an example, this study explores the influence of deep-sea environments on the total efficiency of gear pumps. Firstly, considering the effects of seawater pressure and temperature on the physical properties of the medium and the radial clearance deformation of the gear pump, a mathematical model for the total efficiency of the gear pump was established; the results indicate that the deformation of the gear and pump body is mainly determined by seawater pressure and working pressure. Subsequently, through analyzing the impacts of two factors—temperature and rotational speed—on gear pump efficiency, it was found that as the internal temperature of the gear pump increases, the total efficiency decreases under five different sea depth conditions; as the rotational speed increases, the total efficiency of the gear pump increases; when the rotational speed is controlled, the total efficiency of the gear pump tends to first increase and then decrease with increasing depth. Finally, within different sea depth ranges, the optimal operating temperature and appropriate rotational speed range of the gear pump can be obtained. This paper can provide a certain theoretical basis for the research and development of deep-sea equipment.
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Optimization and Application of Near-Horizontal to Gentle-Inclined to Inclined Mining for Deep Thick and Large Ore Bodies
Abstract:
Abstract: The gently inclined orebody is regarded as one of the difficult-to-mineralize ores. Under the fixed mining system, the conversion of mining for orebodies under different conditions significantly increases the difficulty and efficiency of mining. When a mine transitions from near-horizontal ore bodies to gently inclined or steeply inclined mining, it encounters a problem where some stopes cannot utilize the existing roadways for mining and cutting using the existing tunnels, thus requiring the construction of a large number of new projects. To solve the above issues, a mining plan featuring “stope structure perpendicular to the orebody strike, elimination of cutting raise, and utilizing the ore extraction roadway as the initial free surface and supplementary space” is proposed. It can save trench roadway, undercutting operation, and some ore extraction roadway and haulage roadway. The stability of the structure is demonstrated by FLAC3D software, and the industrial test is carried out in the field. The results show that the goaf model of the 62-A is relatively regular in shape, with the roof and side walls basically remaining intact. The ore loss rate of the stope is 2.3%, and the dilution rate is approximately 8.5%, reducing the amount of mining and cutting engineering by about 14.8%. The craft has the advantages of adapting to changes in the dip angle of the orebody, simple structure, and low engineering quantity, providing reference for similar orebody mining.
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Parameters optimization and mechanism analysis of tailings thickening based on floc trajectory and morphological characteristics
Abstract:
Tailings thickening is the primary step in paste filling technology, and the underflow concentration is a key macroscopic indicator of dewatering effect. The settling behavior and size changes of flocs are important microscopic factors reflecting the dewatering effect of tailings. In order to explore the thickening and dewatering performance of a certain mine"s tailings and optimize its dynamic thickening parameters, an intelligent tailings thickening experimental system was developed by combining high-speed camera, particle tracking, and image processing technologies. Based on response surface analysis, dynamic tailings thickening experiments were conducted. Three multivariate nonlinear quadratic regression equations were established with the mass fraction of feeding slurry, the flow rate of feeding slurry, the unit consumption of flocculant, and the rotation speed of rake frame as influencing factors, and the mass fraction of underflow, axial settling velocity of flocs, and equivalent diameter of flocs as evaluation indicators. The fitting effect of the three models was good. The reasonable range of influencing factors was obtained by analyzing the effects of single factor and multi factor interactions on tailings thickening. By analyzing the dynamic tailings thickening process under different influencing factors, the influence mechanism of axial settling velocity and equivalent diameter of flocs on underflow concentration was elucidated. The dynamic thickening parameters of tailings were optimized. Under the optimal parameter conditions, the underflow mass fraction was 65.76%, the floc axial settling velocity was 5.30 cm/s, and the floc equivalent diameter was 5.31 mm.
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The Impact of Appreciation at Work on Miners’ Proactive Behavior: A Dual-Path Study Based on Cognition and Affect
Abstract:
To effectively stimulate miners’ proactive behavior and address the insufficient intrinsic safety motivation resulting from an overemphasis on punishment and control rather than appreciation and communication in mining safety management, this study draws on the Cognitive-Affective System Theory and Self-Determination Theory. It incorporates in-group identification and family-like exchange as mediating variables and face consciousness as a moderating variable, constructing a moderated chain mediation model. A total of 510 valid questionnaires were collected for empirical testing of the proposed hypotheses. The results show that workplace appreciation promotes miners’ proactive behavior, with an effect value of 0.134. Both in-group identification and family-like exchange play independent and sequential mediating roles between workplace appreciation and miners’ proactive behavior. Face consciousness positively moderates the relationship between workplace appreciation and in-group identification (β = 0.293) and enhances the mediating effect of in-group identification; it also positively moderates the relationship between workplace appreciation and family-like exchange (β = 0.267) and strengthens the mediating effect of family-like exchange. The findings provide practical insights for mining enterprises to implement “people-oriented” safety appreciation management.
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Research on Intelligent Dust Isolation System and Optimal Control of Air Curtain in Tunneling Face
Abstract:
With the improvement of mechanization level of coal mine excavation, the dust production of working face increases significantly, and the risk of dust explosion and ventilation pollution increases. The existing air curtain device has limited dust isolation effect and lacks intelligent control ability. Therefore, a new type of air curtain intelligent dust isolation system is designed, which can dynamically regulate the air flow according to the actual working conditions, and effectively prevent dust and reduce dust. Taking the heading face of a mine in northern Shaanxi as the research object, a finite element calculation model of airflow and dust coupling of air curtain intelligent dust isolation system was established. The influence of air curtain outlet width, deflection angle, distance from secondary dust collection outlet and air volume on dust isolation rate and dust concentration on return air side was simulated and analyzed, and the reasonable range of each parameter was determined. Based on the Box-Behnken experimental design principle, a simulation experiment scheme was established to simulate and obtain data. The response surface method was used to construct a dual-objective optimization model with the maximum dust isolation rate and the minimum dust concentration. The Pareto theory and NSGA-II algorithm were combined to obtain the optimal control scheme. The experimental platform of the system is designed and built. The test results show that the maximum relative error between the model calculation and the measured value is 9.15 %. When the air outlet is 10 m away from the farthest distance from the head, the optimal control scheme is as follows : the air curtain outlet width is 0.006 m, the deflection angle is 7.69 °, the distance from the secondary dust collector is 1.22 m, the air volume is 158.9 m3 / min, the dust isolation rate reaches 89.31 %, and the dust concentration on the return air side is reduced from 315.17 mg / m3 to 145.83 mg / m3, which is reduced by 53.73 %.
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Study on the Time-Dependent Laws of Backfill Mechanical Properties and the Force Characteristics of Bulkheads in Stage Filling Method
Abstract:
Aiming at the issues of unclear stress mechanism of filling retaining walls and lack of scientific basis for design parameters in the subsequent filling stopes of metal mines, this paper takes a certain zinc-gold mine as the engineering background and systematically conducts research on the time-varying characteristics of physical and mechanical parameters of backfill, the evolution law of retaining wall stress, and on-site monitoring. Laboratory tests are carried out to establish mathematical models for the evolution of backfill strength, cohesion, and internal friction angle with curing time; based on the optimized Janssen"s theory, a calculation model for the lateral pressure of retaining walls considering the time-varying characteristics of backfill is constructed, which reveals the stress variation law of retaining walls during the bottom plug filling and layered filling stages; the reliability of the calculation results is verified by combining with on-site monitoring data. The results show that the strength, cohesion, and internal friction angle of the backfill increase non-linearly with curing time, and 16 hours is the key node for the rapid improvement of mechanical properties; the stress of the retaining wall reaches its peak during the first layered filling stage, and then decreases significantly with the extension of curing time. Based on the research results, optimized suggestions are proposed: the height of bottom plug filling should be ≤ 5.0 m, the height of the first layered filling should be ≤ 7.0 m, and the height of subsequent layers can be gradually increased. The research results can provide a theoretical basis and technical support for the design of filling retaining walls and the optimization of filling process parameters in metal mines.
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Study on Stability Analysis and Cement-Soil Replacement Treatment Technology for Talc-Bearing Soft Rock Slopes
Abstract:
To address the local instability of a talc-bearing soft rock slope on the east side of the M Pit in an open-pit copper?cobalt mine, the stability of the slope was evaluated through integrated methods including engineering geological investigation, three?dimensional numerical simulation (FLAC 3D), and limit equilibrium analysis (Slide 2D/3D), its failure mechanism revealed, and a corresponding treatment scheme proposed. The results indicate that while the overall slope remains stable, the exposed talc section within +1335 - +1380 m is unstable. The talc layer, characterized by low strength and mudding upon contact with water, acts as a controlling weak interlayer, leading to a “deep?seated shear combined with shallow tension” failure mode. Accordingly, a comprehensive treatment scheme involving “7?% cement?soil replacement + steel?plastic geogrid reinforcement + blind drainage ditches at the slope toe” was implemented. Nearly one year of on?site monitoring shows that the slope displacement remains generally stable, demonstrating the treatment’s effectiveness, and the technical methodology of “instability mechanism analysis – stability quantitative evaluation – treatment scheme design – effectiveness monitoring feedback” established can provide a theoretical basis and engineering reference for treating slopes containing weak interlayers such as talc.
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Stability Analysis of Surface Structures under Synergistic Backfill Mining in Cluster Orebody Composite Goaf
Abstract:
In response to the urgent need to address common safety issues such as the hazards of old mining voids, ground pressure control in mining activities, and the impact of mining on surface stability during major transformations in numerous non-ferrous mines—shifting from open-pit to underground mining and transitioning from the room-and-pillar method to backfilling. Taking a lead-zinc mine with features like multiple orebody clusters, complex old voids, and mining method transitions as an example, this study explores safety assessments of surface stability in the context of void management and deep mining. The research covers basic investigations, void modeling and backfilling numerical simulation, as well as surface stability analysis. Surface subsidence, subsidence rates, and uneven settlement under various backfilling schemes were evaluated, surface stability levels were classified, and key influence zones were identified. Results indicate that the maximum surface subsidence displacement before backfilling was 64.7 mm, with monitoring point tilt, curvature, and horizontal deformation values meeting Grade I protection standards. For deep expansion, the maximum surface tilt was 0.1963 mm/m, maximum curvature was -0.001656×10-3/m, and maximum horizontal deformation was -0.0678 mm/m, all below the allowable limits for Grade I protection. All surface structures were located in areas with subsidence displacements under 25 mm, ensuring stability. Considering production continuity and time factors, the overall optimal solution is to expand the mining while simultaneously implementing goaf backfill. The study concludes with a comprehensive prevention and control strategy of "mining-governance-monitoring-rehabilitation", offering valuable insights for similar mines.
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Research on the Game Model of Coal Mine Gas Extraction from the Perspective of Multi-Agent Behavioral Evolution
Abstract:
The achievement of gas extraction standards in coal mines is a key link in preventing malignant accidents such as gas explosions, ensuring the safety of underground workers, and ensuring coal mine safety production. The effectiveness of collaborative governance directly affects the stability of the coal mine safety system. Taking coal mine gas extraction as a scenario, a three party evolutionary game model is constructed between government regulatory departments, coal mining enterprises, and frontline operators. By analyzing the stability of each subject"s strategy selection and system equilibrium point, and using MATLAB numerical simulation to analyze the impact of key parameters on system stability, the three party collaborative management inspiration is finally proposed. The results indicate that there are four evolutionary stable strategies in the game model. Among them, the increase in regulatory costs of government regulatory departments will accelerate the convergence speed of loose government regulation and insufficient enterprise extraction, while the increase in punishment will enhance the willingness of enterprises to fully extract, reduce government regulatory demand, and drive frontline personnel to cooperate; The cooperation labor of frontline workers during full extraction in enterprises has a positive driving effect, which can accelerate their own cooperation convergence, reduce the resistance of enterprise execution, and their cooperation strategy is less affected by external factors, which is a stable support for the bottom line of system safety; The input cost of coal mining enterprises" extraction has significant constraints on the evolution of the system. The increase in cost will exacerbate the tendency of enterprises to insufficient extraction, leading to the acceleration of government strict supervision and the slowing down of frontline cooperation convergence. Research contributes to enriching the theory of coal mine safety and provides theoretical and practical basis for improving the compliance rate of gas extraction and reducing the risk of gas accidents.
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Mine water inrush (burst) water source identification model based on SCA-MLP modelLiu Lizhu , Gong Peilin1, Yi Kang1, Su Chao2, Li Peng3
Abstract:
Accurate prediction of the source of mine water disasters is of vital importance for the safe operation of coal mines. In the traditional analysis of the correlation mechanism between groundwater chemical types and the source of water inrush, methods such as Piper"s three-line diagram and principal component load diagram are difficult to achieve precise prediction. This study proposes a SCA-MLP water source identification model that integrates intelligent algorithms and machine learning. It uses Piper"s three-line diagram for qualitative analysis of the water chemical types of aquifers, and employs the REF recursive analysis method to select the main controlling characteristics of water chemistry. By comparing the performance indicators of MLP models optimized by PSO particle swarm optimization algorithm, SSA crow search algorithm, and SCA sine cosine algorithm, the parameters are optimized to achieve precise prediction of the water source type of water inrush in the 1315 working face of Zhaozhuang Mine. The results show that the water chemical types of the fourth series water and the Ouii water are stable. The coal series water and Taizi water have diverse water qualities due to the attachment of cations and mineral dissolution. After recursive analysis, HCO??, Ca2?, Mg2?, SO?2?, and Na? are selected as the main characteristic ions as input indicators for the MLP model. Compared with the PSO-MLP model, SCA-MLP model has an average improvement of over 10.6%, and compared with the SSA-MLP model, it has an average improvement of over 31.8%. Based on the SCA-MLP model prediction, the water source of the water inrush in the 1315 working face of Zhaozhuang Mine comes from the joint recharge of the K8 sandstone aquifer of the coal series water and the K7 and K8 aquifers of the Taizi water. This study provides an intelligent solution for mine water disaster prevention and personnel safety.
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A structural reliability-based LEC-coupled method for assessing roof ground-pressure hazards in underground phosphate stopes
Abstract:
To address the complex roof structures and diverse strata-pressure failure mechanisms encountered in underground mining of gently inclined thick phosphate deposits, as well as the strong subjectivity inherent in “weighting–scoring” risk assessment methods such as the analytic hierarchy process (AHP), this study proposes a structural reliability–LEC coupled approach for assessing roof strata-pressure disaster risk in underground phosphate-mine stopes. Taking a large underground phosphate mine in Kunyang, Yunnan as a case, a roof risk index system is established on the basis of existing corporate criteria, including roof exposure area and duration, fracture development, weighting phenomena, hollow-sounding area, overhanging height, seepage and monitoring anomalies. A “collaborative load–equivalent rock beam” model combined with the first-order reliability method (FORM) is employed to calculate the roof failure probability, which is then mapped onto the likelihood parameter in the LEC model, achieving a mechanics–probability unified representation of the risk value. The method is applied to the K0+200–K0+400 m section of the 1890 m middle-level No. 1 belt conveyor roadway in the No. 2 Kunyang Phosphate Mine and compared with an AHP-based expert scoring approach. The results show that the proposed method highlights major-risk segments, such as the actual roof-fall zone near K0+324.6 m, more clearly than AHP while yielding broadly consistent judgments in general-risk segments, thereby improving the quantitative rigor and engineering applicability of roof ground-pressure hazard assessment under the existing LEC management framework.
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Multivariable Collaborative Prediction Method for Tailings Pond Seepage Line Based on LSTM-iTransformer
Abstract:
Abstract:The variation trend of the tailings pond phreatic line is influenced by multiple factors such as pond water level and the displacement inside and outside the dam. However, existing prediction methods still face challenges in multi-source feature fusion and modeling complex temporal dependencies. To address these issues, this paper proposes a multivariate collaborative prediction method for tailings pond phreatic lines that integrates Long Short-Term Memory (LSTM) networks with iTransformer. Firstly, LSTM is used to extract local temporal features of factors such as pond water level and dam internal and external displacement. Then, through a gated fusion unit, the local temporal features extracted by LSTM are dynamically fused with the original input to construct information-enhanced hybrid features. Finally, an iTransformer module is introduced to mine global dependencies among multi-source monitoring data across variable dimensions, aiming to improve the accuracy of phreatic line variation trend prediction. To validate the model's predictive performance, comparative experiments and generalization tests were conducted using a tailings pond from a lead-zinc mine in Yunnan Province. The experimental results show that the LSTM-iTransformer model achieves the best prediction performance, with the coefficient of determination (R2), mean squared error (MSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) reaching 0.983113, 0.000057, 0.006019, and 0.041025, respectively, outperforming the other four comparative models. Moreover, across monitoring points at different cross-sections, its prediction accuracy consistently leads all comparison models, demonstrating that the model possesses strong cross-point generalization capability and provides valuable reference for predicting the variation trends of tailings pond phreatic lines.
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Study on the Effect of Coal Gasification Slag Content on the Mechanical Properties of Paste Filling Materials
Abstract:
To study the mechanical properties of paste filling materials with different coal gasification slag contents, paste filling specimens were prepared using mechanically ground coal gasification slag (200 mesh), desulfurization gypsum, fly ash, cement, and coal gangue as raw materials. Uniaxial compression tests were conducted on paste filling specimens with different coal gasification slag contents to assess their response under uniaxial compression. The analysis included stress-strain curves, deformation and failure characteristics, acoustic emission patterns, and microscopic features of fracture surfaces of samples with different slag contents. The results indicate that the uniaxial compressive strength of paste filling samples with coal gasification slag increased with curing age, and exhibited a trend of initially increasing and then decreasing with an increase in slag content. As slag content rose, the failure mode shifted predominantly from tensile failure to a conjugate mode of tensile-shear failure, ultimately transitioning to shear failure. The location of failure shifted from edges of filling body towards its centre, accompanied by an increase in the severity of failure. Compared with samples with 1.8% coal gasification slag content, the average porosity of samples with 5.6% coal gasification slag content decreased by 13.24%, the average maximum pore area decreased by 39.00%, and the average probability entropy decreased by 2.16%. The average porosity of the coal gasification slag paste filling body samples with 11.7% of the coal gasification slag content decreased by 35.15%, the average maximum pore area decreased by 87.01%, and the average probability entropy decreased by 4.64%. The appropriate addition of coal gasification slag provides more active substances for the formation of Aft and other compounds, promoting reaction and further enhancing the uniaxial compressive strength of paste filling samples. The research results can provide some reference for paste filling mining.
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Damage evolution of fractured rock mass under coupled impact loading and confining pressure
Abstract:
To quantitatively analyze the dynamic response of pre-flawed rock masses under the combined action of impact loading and confining pressure, a numerical model of a split Hopkinson pressure bar (SHPB) system was established in ANSYS/LS-DYNA based on one-dimensional stress wave theory and the Holmquist–Johnson–Cook (HJC) dynamic damage constitutive model. Dynamic impact simulations were conducted on prismatic marble specimens with different pre-existing flaw inclinations under various initial confining pressures. The results show that, at a given strain rate, the pre-peak portions of the stress–strain curves under different conditions largely coincide, and macroscopic crack initiation mainly occurs within a short time interval close to the peak stress. Confining pressure significantly enhances dynamic strength: the peak stress increases with confining pressure, and the increment associated with variations in flaw inclination becomes more pronounced at higher confining pressures. Overall, the cracking pattern is dominated by an “X”-shaped shear failure mode; based on crack trajectories and initiation mechanisms, five typical crack types and one fragmentation feature can be identified. With increasing confining pressure, the crack network becomes more complex and fragmentation intensifies. Energy analysis indicates that higher confining pressure reduces the proportion of reflected energy while increasing the proportions of transmitted and absorbed energy; the dissipated energy generally rises with confining pressure and, with respect to flaw inclination, shows a local decrease near ~45° followed by a rapid increase. These findings provide a reference for damage assessment and stability control of fractured rock masses subjected to the combined effects of dynamic disturbances (e.g., blasting vibration) and in-situ stress.
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Rock Damage Identification Method Based on Adaptive Sampling and Optimized Kriging
Abstract:
High-precision reconstruction of rock mass wave velocity fields is crucial for hazard early warning and stability assessment in complex geological conditions such as deep mining and tunnel engineering. To address the issues of low computational efficiency and insufficient interpolation accuracy of traditional Kriging interpolation methods under complex geological conditions, this paper proposes a wave velocity field reconstruction method that integrates adaptive sampling with optimized block Kriging. The method first introduces an adaptive sampling strategy, which preserves key spatial features while utilizing gradient differences to eliminate outliers and significantly reduce data volume, thereby ensuring interpolation accuracy and improving computational efficiency. Subsequently, an enhanced Sparrow Search Algorithm is incorporated to intelligently and globally optimize the dynamic partitioning strategy of block Kriging based on physically constrained blocks, thereby enhancing the characterization capability for high-variability zones. Experimental results show that, while compressing the data volume by approximately 30%, the proposed method maintains the accuracy of wave velocity field reconstruction and improves computational efficiency by about 33.08%, with a significant reduction in cross-validation error. This method achieves high-precision spatial localization of internal damage zones in rock masses and provides reliable technical support for rock mass stability evaluation.
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Influence of Deep Orebody Mining on the Stability of Surface Buildings Underneath Shallow Backfilled Goaf
Abstract:
To assess the impact of deep orebody mining on surface buildings underneath a shallow backfilled goaf, this study takes the Mengjiagang Iron Mine as a case. Based on the "three-zone theory," the safe mining depth was analyzed, and a three-dimensional numerical model was constructed using the 3DMine-Rhino-FLAC3D coupling method to simulate the deformation response of the surface and structures after deep orebody mining and backfilling. The results indicate that the minimum vertical mining distance in the study area is 282.5?m, which exceeds the theoretical safe mining depth, and mining-induced effects do not reach the surface. After mining completion, the maximum surface subsidence is 40?mm, and all surface deformation indicators remain relatively small. The horizontal deformation, tilt deformation, and curvature deformation values at monitoring points along the Mujia Railway, adjacent highways, and villages all meet the requirements of current regulations, demonstrating that deep orebody mining has a controllable impact on surface buildings. This study can provide a reference for safe mining and surface protection under similar conditions.
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Safety Protection Method for Mining Truck Operations in Open-Pit Mine Waste Dumps
Abstract:
Aiming at the problems of frequent displacement changes of continuous safety retaining walls in the unloading area of the working platform of open-pit mine waste dump, and the lack of systematic safety protection mechanisms for mining trucks during dumping operations at night and under low visibility conditions, a dynamic electronic fence technology based on the GAC model is proposed. This technology achieves real-time positioning and tracking of the displacement changes of the safety retaining walls in the waste dump, and significantly enhances the monitoring, early warning, and safety protection capabilities of mining trucks by combining high-precision positioning information and coordinate guidance. The research employs vehicle-mounted high-precision positioning terminals to collect data from the open-pit mine waste dump, utilizes the gradient changes of grayscale values in grid images to record the distribution characteristics of trajectory points in key areas, and extracts the contour boundaries of feature regions from grid images based on active contour technology. As the feature regions dynamically change with the displacement of the mining truck dumping platform, the system can adaptively generate virtual dynamic electronic fences. Through model construction and simulation application at the open-pit coal mine waste dump in Xinjiang Heishan Mining Area, it is verified that the model can effectively track the displacement changes of retaining walls, providing a reliable safety protection solution for mining truck operations.
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Numerical simulation of basalt-polypropylene fiber concrete under Brazilian splitting and uniaxial compression
Abstract:
To gain an in-depth understanding of the mechanical properties of fiber-reinforced concrete, this study conducts numerical simulations of basalt-polypropylene fiber concrete under Brazilian splitting and uniaxial compression tests using the ABAQUS finite element software, based on the principle of explicit dynamic analysis. A refined three-dimensional solid model was established, in which the Concrete Damaged Plasticity (CDP) model was adopted to describe the tensile and compressive damage behavior of concrete, and three-dimensional truss elements were utilized to simulate the reinforcing effect of fibers. An innovative dynamic analysis approach was introduced to effectively resolve the convergence issues commonly encountered in traditional static simulations. The results demonstrate that the incorporation of both basalt and polypropylene fibers effectively enhances the peak strength and residual strength of concrete. The fiber volume fraction exhibits a significant influence on the strengthening effect, with a general trend indicating that a higher fiber content leads to a more considerable improvement in the residual strength. This research systematically reveals and elucidates the enhancement mechanism of fiber-reinforced concrete through numerical methods, providing a theoretical basis for its engineering applications.
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Research Status and Prospects of Machine Learning-based Prediction of Harmful Effects of Blasting in Typical Open Pit MinesLearning
Abstract:
In order to predict and control the various harmful effects of blasting in open-pit mines with greater accuracy, such as vibrations, flying rocks, noise, and dust, and to address the limitations of traditional empirical formulas in handling nonlinear problems – specifically their insufficient accuracy and weak generalization capabilities – this paper reviews the current status and future trends of machine learning technology applications in this field. Firstly, the formation mechanisms of harmful effects from blasting and the limitations of traditional prediction methods are explained. In the following section, the construction process of machine learning prediction models is detailed. This process includes key stages such as data collection, preprocessing, feature engineering, model training, and evaluation. The paper systematically reviews and analyses the application progress, performance characteristics, and applicable scenarios of mainstream models such as artificial neural networks (ANN), support vector machines (SVM), ensemble learning (e.g. random forests, XGBoost), and deep learning (e.g. LSTM, CNN) in predicting peak peak velocity (PPV) of blasting vibrations, flying rock distance, and environmental pollutant concentrations. A substantial body of research has indicated that machine learning models, with a particular emphasis on hybrid intelligent models that combine machine learning with intelligent optimization algorithms such as genetic algorithms and particle swarm optimization, have the capacity to enhance prediction accuracy and robustness to a considerable extent when compared to traditional methods. The present study examines the contemporary challenges confronted in the acquisition and evaluation of data, the capacity for model generalisation, interpretability, and the prediction of multi-effect coupling. It further explores prospective advancements in the integration of IoT, XAI, and digital twin technologies to construct intelligent, integrated prediction and decision support systems. The objective is to furnish theoretical underpinnings that facilitate the realisation of safe, efficient, and environmentally sustainable development in the context of open-pit metal mine blasting operations.
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Research and Application of Zone Collaborative Mining Technology for Thick Ore Bodies in Complex Fault Zones
Abstract:
The hanging wall and footwall of the ore body in Zone Ⅲ of Yinman Mining are developed with uneven kaolinitized fault zones, leading to high risks of stope collapse and easy softening of backfill. Conventional up-dip horizontal cut-and-fill methods can hardly reconcile safety and economic efficiency under such conditions. To address this problem, a zonal collaborative mining strategy for thick orebodies under “central competent zone–peripheral fractured zone” conditions is investigated. Segmental long-hole stoping with delayed backfilling is adopted in the central competent zone, while a wall-supported segmented filling method is applied in the fractured zones, and the matching relationship between stope structural parameters and backfill strength is established. Required backfill strength for different zones is calculated using five analytical approaches, including the Thomas model and Mitchell method, and three-dimensional numerical simulations are employed to analyse the effects of mining sequence, stope width and safe exposure area on the stability of the rock–backfill system. Industrial tests are carried out separately in the central competent zone and fractured peripheral zones, with monitoring of technical–economic indicators and rock mass deformation. Results show that the zonal collaborative scheme increases single-level output in the competent zone to about 4500 t and stabilizes daily production in the fractured zone at 390–400 t, while significantly reducing development ratio and unit mining cost; stope roof convergence is generally controlled within 30–40 mm. Recommended backfill strengths and safe exposure areas suitable for thick orebodies with complex fracture zones are obtained, providing a technical basis for safe, economic and efficient extraction.
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Instability Mechanism and Stability Control of Gently Dipping Orebody Stopes under the Coupling Effect of Surface Load and Mining-Induced Disturbance
Abstract:
Regarding the stability control of stope surrounding rock and the safety issues of surface waste rock dumps in gently inclined orebodies under the coupled action of mining-induced disturbances and surface loads, indoor rock mechanical tests were conducted to determine the mechanical parameters of key strata. Combined with physical similarity simulation based on Digital Image Correlation (DIC) and three-dimensional numerical simulation, the fracture evolution characteristics of stope surrounding rock under dual disturbances, as well as the response laws of stress and displacement fields, were systematically studied. The experimental results indicate that mining-induced disturbances trigger stress redistribution in the surrounding rock, and the superposition of surface loads increases the maximum vertical displacement of the stope roof directly beneath the waste rock dump by approximately 12%. A settlement center, consistent with the theoretical boundary of the mining-induced pressure relief arch, forms on the surface. Tensile stress concentrations are observed in the roof, floor, and upper sections of the stope surrounding rock, while compressive stress concentrations are found in the crown and sill pillars between mining levels. Backfill mining mitigates stress concentration and deformation transmission, reducing the stress in inter-level crown and sill pillars by about 72% and the tensile stress in the roof by about 15%. This effectively alleviates the unloading effect and enhances the stability of the stope-surface system. Field monitoring at the engineering site has verified the effectiveness of the implemented measures, providing a scientific basis for the safe mining of similar surface structure-stope coupled systems.
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Influence Mechanism of Geometric Features of Surface Structure on Shear Stress Distribution and Stability of Slope
Abstract:
The stability of rock slopes is significantly controlled by the geometric characteristics of structural planes, especially in areas where joints and fractures develop. The shear stress concentrates along these structural planes and evolves into slip zones, which can trigger local instability. Using the Baiyunebo open-pit mine bench slope as an engineering prototype, joint dip angles and intersection geometry are selected as key control factors. A photoelastic model is established based on the principle of geometric similarity, and shear stress distribution for different joint configurations is obtained through six-step phase shifting and image processing. The safety factors for various joint angles are calculated using both limit equilibrium methods and trial methods. A three-dimensional numerical model containing jointed structural planes is established using FLAC3D strength reduction, and the evolution of the minimum principal stress field, strength-stress ratio field, and displacement field is analyzed through comparison. The results show that the high shear stress areas mainly occur at the ends of joints and at the sharp angles of intersections. As the intersection angle decreases, high shear stress transitions from discrete patches to continuous shear weakening zones along the joint. The number of local peak values and the effective width of the intersection zone increase. When the joint dip angle increases from 30 ° to 70 °, the safety factor increases monotonically from approximately 1.13 to 1.56. Shallow dip configurations tend to form continuous shear slip surfaces, while steep dip configurations are more effective in weakening the connectivity of shear slip channels and improving overall stability. These results provide a quantitative basis for the stability evaluation of jointed rock slopes and engineering control designs for sharp-angled intersecting structural planes.
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The influence of loading rate on the mechanical properties and acoustic emission characteristics of saturated sandstone under cyclic loading and unloading
Abstract:
In order to investigate the effect of loading rate on the fatigue mechanical properties and acoustic emission characteristics of saturated sandstone. The evolution characteristics of saturated sandstone strength, Kaiser effect, and acoustic emission parameter RA-AF values under different loading rates were studied through multi-stage cyclic loading unloading acoustic emission experiments. The experimental results show that during low-speed loading, the pore water fully migrates, lower than that of dry sandstone, and increases with increasing loading rate. and the hysteresis loop curve is wide and gentle. The failure mode is mainly characterized by shear penetration accompanied by many secondary tensile cracks. During high-speed loading, the viscous resistance of the water body increases, and the cracks are mainly localized tensile fractures. Under low-speed loading, FR<1 (showing Felicity effect) increases, while under high-speed loading, FR>1 (Kaiser effect) increases. The rapid loading suppresses the accumulation of hydraulic damage and enhances the stress memory effect of acoustic emission. As the loading rate increases, the proportion of tensile cracks gradually increases. The failure mechanism transitions from shear slip accompanied by tensile cracks to brittle tensile failure. The influence mechanism of loading rate on the fatigue mechanical properties and acoustic emission parameter response characteristics of saturated sandstone was elucidated, laying a theoretical foundation for the stability analysis of rock engineering in water rich environments.
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Intelligent Alignment Method and Software Development for Multi-Source Mine Borehole Trajectories
Abstract:
To address the challenges of low efficiency, limited accuracy, and heterogeneous data sources in comparing designed and measured trajectories of mine borehole groups, this study proposes an intelligent trajectory alignment method based on multi-source data fusion, together with a supporting software system. The method performs layer-by-layer parsing of multi-format design drawings and extracts borehole trajectory segments, while measured trajectories are standardized through outlier removal and spline-based interpolation. By integrating inclination-angle matching with a dynamic coordinate-translation strategy, the method enables fully automated and high-precision alignment between designed and measured trajectories. A field application to a fan-shaped borehole group demonstrates that the system can adaptively process multi-source trajectory information originating from CAD design drawings and in-situ measurement data. The proposed method achieves an inclination-angle deviation accuracy of ±2°, with most depth deviations controlled within ±1.5 m. It effectively identifies borehole trajectory deviations and provides automatic visualization and structured data exporting. The results indicate that the method and its software implementation offer a practical and reliable solution for quality control in mine drilling operations and support the development of intelligent mining construction.
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Experimental Study on the Effects of Soil Nutrient Environment in Mining Areas on the Biomass Accumulation of Kudzu
Abstract:
Vines have been widely applied in ecological restoration of mine slopes due to their rapid growth, strong climbing ability, nitrogen-fixing capacity, and medicinal value. The scarcity of readily available nutrients in the original substrate of mining areas is a key factor limiting the normal growth and biomass accumulation of vines. To facilitate normal growth of kudzu, different amounts of readily available nitrogen, phosphorus, and potassium were applied to the original substrate. Comparative experiments and significance analysis were conducted to examine parameters including total nitrogen, phosphorus, and potassium content in kudzu leaves, light-capturing characteristics, and biomass. Results indicate that the total nitrogen, phosphorus, and potassium content in kudzu leaves positively correlates with the application rates of available nitrogen, phosphorus, and potassium. When two of the available nutrients are applied at moderate rates and the application rate of the third nutrient is fixed, adjusting the application rate of the third available nutrient increases the corresponding nutrient content in the leaves as its application rate increases. The content of available nitrogen, phosphorus, and potassium significantly influenced the light-capturing characteristics of kudzu leaves. Leaves with high nitrogen, medium phosphorus, and medium potassium exhibited the highest leaf biomass, specific leaf area, and dry matter mass among all treatment groups, with values increased by 65.8%, 16.3%, and 26.4% respectively compared to the original substrate. Leaf biomass and specific leaf area showed extremely significant correlations with available nitrogen and significant correlations with available phosphorus. The available nitrogen, phosphorus, and potassium content significantly influenced the biomass accumulation and net photosynthetic rate of kudzu. High nitrogen, medium phosphorus, and medium potassium treatments yielded the highest biomass accumulation and net photosynthetic rate among all treatment groups, representing increases of 38.9% and 58.4%, respectively, compared to the original substrate group. Increasing the content of available nitrogen, phosphorus, and potassium in the original substrate can enhance the photosynthetic physiological and ecological adaptability of kudzu from various aspects, thereby increasing its biomass.
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Evolution of Lightweight Concrete Fatigue Considering Recyclable Coal Gangue Ceramsite Distribution
Abstract:
The substitution of natural aggregates with recyclable coal gangue ceramsite light aggregates (RLA) presents an effective strategy for producing lightweight concrete. Nevertheless, the substantial disparities in the physical and mechanical properties between RLA and conventional aggregates render the fatigue behavior of RLA concrete insufficiently understood. To address this gap, a virtual fatigue testing methodology for four-point bending of concrete was developed, incorporating the irregular morphology and spatial distribution of aggregates. By integrating laboratory experimental data with numerical simulations, this study examined the effects of RLA particle size, replacement ratio, spatial distribution, and stress level on the fatigue life of concrete, as well as on the initiation and propagation of fatigue cracks. The findings indicate that the average discrepancy between numerical predictions and experimental results remains below 7%, with a maximum deviation not exceeding 10%, thereby validating the reliability of the virtual testing approach. This method effectively replicates the initiation and progression of fatigue cracks, offering a novel framework for analyzing the fatigue characteristics of RLA concrete. Specifically, an increased replacement rate of 20–30 mm RLA tends to generate weak zones, complicating crack propagation paths. Conversely, higher substitution levels of 10–20 mm RLA shift fatigue failure mechanisms toward micro-cracking within the mortar. The incorporation of 5–10 mm RLA, owing to its favorable compatibility with mortar, mitigates interface cracking. Furthermore, elevated stress levels contribute to more intricate crack patterns without altering the loci of crack initiation.
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Research on Mine Safety Evaluation Based on AHP-MIV-BP Model
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Mine safety evaluation is a crucial approach to ensuring production safety in mining operations and plays a vital role in enhancing the overall level of mine safety management. To improve the objectivity and accuracy of such assessments, a mine safety evaluation model (AHP-MIV-BP) has been proposed, integrating the Analytic Hierarchy Process (AHP), Mean Impact Value (MIV), and Back Propagation (BP) neural networks. Firstly, the model determines the weights of each index through AHP and generates the expected output value as the target output of the BP neural network. Subsequently, the MIV method was employed to select 15 key indicators with significant impact on mine safety from 32 original indicators and used as variable inputs of BP neural network. Finally, the BP neural network is employed to predict safety levels, classifying the mine safety levels into four categories: I, II, III, and IV. The results indicate that the model achieved a classification accuracy of 96% on the test set, with macro-average precision, recall, and F1-scores of 0.96、0.96 and 0.95, respectively. Moreover, The AUC values for all categories exceeded 0.95. Compared with the BP 、MIV-BP and AHP-BP models, the AHP-MIV-BP model exhibited overall performance improvements, demonstrating higher predictive precision, generalization capability and stability, thereby providing effective technical support for intelligent assessment of mine safety risks.
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Optimization of motion path for the concentrate extraction robotic arm of spiral concentrator based on LC-RRT*
Abstract:
Addressing the challenges posed by the small interlayer distance of the spiral concentrator and the narrow operating space for concentrate extraction, which make it difficult for the spiral concentrator's operating robotic arm to achieve target positioning and extraction actions, an LC-RRT* spiral concentrator robotic arm motion planning algorithm is proposed. The LC-RRT* algorithm first combines a target-biased sampling strategy to enhance the goal-oriented nature of the sampling process. Secondly, it effectively improves the computational efficiency of the RRT* algorithm in path planning in complex obstacle environments by adding a bidirectional search strategy. At the same time, an improved artificial potential field is introduced to optimize algorithm sampling and ensure the safety of the planned path, solving the problem of local minima during the algorithm's path planning process. Finally, the idea of backtracking is employed to effectively remove redundant nodes from the path, thereby reducing the total path cost. The results of the robotic arm motion simulation experiments show that the LC-RRT* algorithm achieves an average of 203.11 nodes, 1.03s of planning time, and a path length of 198.13mm. These indicators, such as path planning time and path length, are significantly better than those of other models, greatly improving the accuracy and stability of the robotic arm's path planning. The LC-RRT* algorithm exhibits excellent path planning and obstacle avoidance effects in the actual working environment of the spiral concentrator, effectively solving the problem of concentrate extraction path planning for the spiral concentrator's operating robotic arm.
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Influence of Grouting Layer Dip Angle on the Mechanical Behavior and Failure Mechanism of Cement-Mudstone Composite
Abstract:
To address the issue that the effectiveness of grouting reinforcement for fractured mudstone in roadways is significantly influenced by the inclination angle while its underlying control mechanism remains insufficiently understood, composite samples with inclination angles α of 0°, 15°, 30°, 45°, and 60° were prepared using natural mudstone and engineering cement. By integrating uniaxial compression tests, acoustic emission monitoring, and PFC 3D numerical simulation, and after calibrating and validating the meso?scale parameters, the influence of the inclination angle on the macro?mechanical properties, failure modes, and meso?scale damage characteristics of the samples was investigated to reveal the regulatory mechanism governed by the inclination angle. The results indicate that the inclination angle of the filling layer is a key controlling factor for both strength and failure mode. As the inclination angle increases, the failure mode transitions from axial splitting to interfacial shear slip, accompanied by a nonlinear attenuation in strength. The most unfavorable critical inclination angle is α = 30°, where the strength reaches its minimum value of 8.78?MPa, representing a 47.5% reduction compared to α = 0°, and the proportion of shear cracks increases progressively. The research outcomes were applied to roadway reinforcement in the Pansan Mine of Huainan, resulting in a 28.5% reduction in support failure risk and a 17.2% cost saving compared to conventional solutions, thereby providing critical evidence for the design of roadway support systems.
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Study on New Technology of Combined Enrichment and Recovery of Refractory Bismuth Middle Ore Dressing and Smelting
Abstract:
As a scarce "green metal" in the world, bismuth is widely used in medicine, semiconductor, nuclear industry and other fields. However, it often coexists with polymetals, and comprehensive recovery is difficult. Aiming at the core problems of refractory bismuth, such as fine ore particle size, low pulp mass concentration, and strong inhibition by front-end chemicals, this paper carries out research on efficient beneficiation and comprehensive utilization, and optimizes and develops "flocculation dilution re-sedimentation-acid leaching and activated carbon pretreatment-flotation enrichment and bismuth extraction" new combined beneficiation and smelting process. This process accurately solves the pain points of difficult dispersion and slow sedimentation of fine minerals through lime flocculation and sedimentation, and then through the synergistic effect of hydrochloric acid leaching and activated carbon dechemization, compared with the existing single dechemization or leaching process, it can more completely remove the chemical inhibition on the mineral surface, significantly improve the flotation activity of bismuth, and finally realize the efficient recovery of bismuth resources through flotation. In the whole process closed-circuit test, under the condition that the bismuth grade of the feed ore is 4.78%, the bismuth concentrate with bismuth grade of 22.01% and recovery rate of 86.67% is finally obtained, and the yield is 20.06%. The research shows that the combined pretreatment-flotation process of dressing and smelting effectively solves the problem of difficult recovery of bismuth minerals, and provides an important technical reference for the comprehensive recovery of polymetallic associated bismuth resources.
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Numerical simulation of stress distribution characteristics on wall of orepass under different ore-drawing velocity
Abstract:
In order to elucidate the relationship between the abrasion of the orepass wall and the ore-drawing velocity when the orepasse is full of ore, taking the orepass of an open-pit mine as the research subject, the PFC2D was employed to establish a numerical model of the orepass, and a dynamic stress distribution detection platform during the ore-drawing process of the orepass was set up to investigate the dynamic stress distribution characteristics of the orepass wall. The results indicate that as the draw velocity increases, the wall stress magnitude progressively rises due to “arching-induced stress amplification.” The dynamic stress consistently exceeds the static stress down to a vertical depth of 105m. Under varying draw velocities, the maximum wall stress occurs at a depth of 70m, ranging from 1.62 to 2.26 times the static lateral pressure (static side pressure) at this location. As draw velocity increases by increments of 0.2 m/s, the increase ratio of horizontal lateral pressure (horizontal component of wall stress) on the orepass wall remains approximately constant at a factor of 1.15. Conversely, the increase ratio of friction force (frictional stress component) gradually diminishes, reaching a minimum of 1.03 times. Furthermore, regression analysis was performed on the dynamic horizontal pressure and friction coefficient acting on the orepass wall, yielding a fitted empirical formula for calculating dynamic stresses. This formula allows the determination of dynamic stresses at different draw velocities based on calculated static stress values. The findings provide significant theoretical insights for evaluating orepass wall degradation (damage assessment), contributing to enhanced orepass service life.
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Optical Intelligent Mineral Processing: Theoretical Mechanism, Technical System, and Development Prospect
Abstract:
Optical intelligent mineral sorting represents a significant technological innovation in the field of mineral processing, with notable advances achieved in both theoretical research and engineering applications in recent years. Article systematically elaborates on the theoretical foundation and technical equipment system underlying the development of optical intelligent mineral sorting. At the theoretical level, the sorting rationale is constructed based on differences in minerals properties such as color, luster, transparency, luminescence, refractive index, and absorption spectra; the optical detection system enables precise acquisition of spectral features and morphological information via optical sensors; data intelligence processing relies on advanced algorithms to enhance recognition efficiency; and the sorting execution system accomplishes the accurate separation of target minerals. At the technical equipment level, technologies including machine vision, multispectral/hyperspectral imaging, near-infrared spectroscopy, X-ray transmission/fluorescence, and laser-induced breakdown spectroscopy (LIBS) achieve precise identification and efficient sorting tailored to different mineral characteristics, demonstrating a trend toward multi-technology integration. Currently, the core advancement in optical intelligent ore sorting lies in the systematic integration of multi-source sensors and their industrialized synergy with conventional mineral processing technologies. Simultaneously, Susceptibility to environmental interferenceand addressing the high costs associated with equipment and maintenance remain critical challenges demanding urgent solutions. However, as this technological system progresses toward full-scale industrialization, its efficacy boundaries are increasingly apparent. Persistent industry pain points include insufficient equipment capability, complex mineral symbiosis, information distortion in fine particles, and the lack of a standardized framework. Article aims to provide theoretical support and practical reference for the intelligent advancement of mineral sorting technology, while also offering insights and perspectives on its future development directions.
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Beneficiation Test of a Gold Mine and Comprehensive Utilization Study of Tailings Under the Tailings-Free Concept
Abstract:
Based on the tailings-free mining concept, a study on mineral processing and comprehensive tailings utilization was conducted for a magmatic hydrothermal gold deposit in Hunan. A tailings-free mining technology system was established, comprising the "gravity-flotation combined process for gold recovery—comprehensive recovery of quartz from gold tailings—full backfilling of remaining tailings." This successfully achieved comprehensive utilization of all ore components and resolved policy and technical bottlenecks restricting mine development. The specific technical route involves: recovering gold through the gravity-flotation combined process, comprehensively recovering quartz from gold tailings, and using all remaining tailings for underground backfilling. Through systematic experimental research, a process combining vertical centrifuge gravity separation and flotation for gold recovery was determined, producing a gold concentrate with a grade of 81.69 g/t Au and a recovery rate of 97.06%. Quartz was comprehensively recovered from gold tailings using a "desliming—high-intensity magnetic separation—reverse flotation" process, yielding a quartz concentrate with a SiO2 grade of 98.86% and a recovery rate of 65.37%. The remaining tailings, accounting for 38.23% of the yield after gold and quartz recovery, were fully utilized as backfill aggregate. The technical and environmental indicators are excellent, providing a reference for tailings-free development in similar mines.
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Optimal Path Planning Method for Robotic Arms in Coal Mine Tunnel Environments
Abstract:
The intelligent construction of mines is a core driver for enhancing coal mining efficiency and safety. However, in underground environments, the widespread issues of coal dust and mud pollution in mine roadways severely restrict the stable operation of intelligent equipment and the improvement of working conditions, urgently requiring effective solutions. To address the severe coal dust and mud pollution in mine roadways, coupled with the inefficiency and inadequate coverage of traditional manual cleaning methods, proposes a trajectory planning and control system for a vehicle-mounted robotic arm designed for roadway cleaning tasks. By employing the artificial potential field algorithm for path planning, a potential field function that conforms to the roadway wall surface is constructed, achieving uniform coverage and natural smoothness of the path. This overcomes the shortcomings of traditional methods, such as path deviation and frequent jitters in complex environments. Furthermore, a multi-objective value function with dynamically adjustable weights is designed, and a control model is established by integrating an optimal control algorithm to comprehensively optimize trajectory tracking accuracy, motion smoothness, and energy consumption. Simulation and experimental results demonstrate that the proposed method achieves a path planning success rate of 98% and a cleaning coverage rate of 97%, effectively avoiding collisions with obstacles and resolving the issue of insufficient coverage inherent in traditional manual cleaning.
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Detection on Vegetation Change in Open-Pit Mining Areas Based on Bi-Temporal Feature Interaction
Abstract:
An Open-Pit Mine Vegetation Change Detection Network (OPMV?CD) is proposed to address insufficient bi-temporal feature interaction and poor adaptability to complex scenes in vegetation change detection for open?pit mining areas, aiming to improve change detection performance in this domain. In the feature extraction stage, OPMV?CD employs a Spatial Feature Interaction (SFI) module and a Channel Feature Exchange (CFE) module. The SFI module enhances critical spatial features by differential weighting and suppresses noise, while the CFE module optimizes channel exchange strategies via learnable parameters to increase feature diversity. In the feature fusion stage, a Multi-modal Attention Feature Fusion (MM?AFF) module is used, which combines channel and spatial attention mechanisms and accounts for inter-temporal correlation through modality-weighted fusion, thereby fully exploiting bi-temporal feature associations and producing more accurate fused features. In addition, a lightweight backbone is designed to reduce parameter count and enlarge the receptive field to capture global contextual information. Experiments on an open?pit mine vegetation change dataset show that OPMV?CD achieves an F1 score of 0.9216 with only 2.28M parameters, significantly outperforming comparative methods. Ablation studies further validate the effectiveness of each module. The results indicate that the proposed method enables high-precision vegetation change detection in open?pit mining areas and provides reliable evidence for ecological environment management.
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Research on the Application of Pressure Support Technology for "Empty Windows" on the Side of the Mining Roadways
Abstract:
To address frequent failure of conventional stiff supports and excessive deformation in deep soft-rock longwall gateroads, a window destressing support concept is adopted, in which controllable “windows” along both ribs guide stress into the deep rock mass and dissipate energy within limited displacements. A modified creep model was formulated by embedding a Mohr–Coulomb plastic element into the Burgers rheology (Maxwell + Kelvin + Mohr–Coulomb), and a three-dimensional elasto-plastic model was built in FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions). An equivalent brick representation was used to capture the shear–bending coupling of bolt–mesh, and three window (mesh) sizes—30 cm×30 cm, 40 cm×40 cm, and 50 cm×50 cm—were compared in terms of stress–displacement responses and control performance. The calibrated initial stress shows a 2.13% relative error to theoretical values, and the disturbance radius is about 16.0 m. The 40 cm×40 cm scheme releases 25.49% of compressive stress, stabilizes rib displacements below 2.1 cm, and achieves a 56.39% reduction versus the baseline, thereby balancing destressing and deformation control; the 50 cm×50 cm scheme, while offering additional release, tends to enlarge tensile zones and weaken structural integrity. Based on the numerically optimized results, the 40 cm × 40 cm “void window” yielding scheme was implemented in the field support of the 10104 roadway, together with a mine-pressure monitoring program. The monitoring results show that the roof separation was generally controlled within approximately 15 mm, the monthly drivage rate increased by about 25–35%, the consumption of support materials was reduced by around 20%, and the roadway maintenance cost was significantly decreased, thereby demonstrating the engineering applicability and control effectiveness of the proposed technology.
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Design and Performance Testing of Emergency Rescue Air Breathing Equipment for High Altitude Coal Mines
Abstract:
In coal mine emergency rescue work, oxygen breathing apparatus is a key protective equipment for underground operations and rescue. Its performance reliability directly affects the life safety of rescue personnel and the effectiveness of disaster relief. Among the oxygen supply methods in plateau areas, fixed oxygen inhalation stations have poor mobility, and carbon fiber oxygen cylinders and oxygen bags have short endurance time, both of which are difficult to meet the long-term operation needs in high-altitude areas. In response to the oxygen-deficient environment of plateau coal mines, this study developed a new type of emergency air breathing apparatus. This device uses intelligent hybrid oxygen supply technology, optimizes gas flow with a spiral molecular sieve structure, achieves efficient separation of oxygen and nitrogen, and can stably supply breathing gas with an oxygen concentration of 21%. In response to the environmental characteristics of low pressure and low temperature in the plateau, the system integrates a titanium lithium battery pack, an intelligent temperature control power supply module, and a multi-stage gas filtration system, effectively solving the problems of unstable oxygen supply and insufficient endurance of traditional equipment. Experiments show that in environments below an altitude of 5500 meters, this device can maintain the user"s blood oxygen saturation above 92%, with high oxygen generation efficiency, fast response speed, easy operation, safety, and energy saving. It significantly enhances the safety guarantee level of emergency rescue and underground operations in plateau mining areas.
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Stability Analysis and Optimization of High and Large Filling Retaining Wall in Mining StopeBased on FLAC3D
Abstract:
Aiming at the stability issue of retaining walls during high-volume filling in deep mine high stopes, this study takes Macheng Iron Mine as the engineering background and employs FLAC3D numerical simulation to systematically analyze the influence of wall size, single-stage filling height, and wall thickness on the mechanical deformation characteristics and stability of the filling retaining wall. The results show that wall displacement is positively correlated with wall size and single-stage filling height, and negatively correlated with wall thickness. The degree of influence of each factor on stability follows the order: wall thickness > wall size > single-stage filling height. For walls with large width and small thickness, stability can be improved by adding reinforced wall columns. Based on this, an optimized wall structure scheme is proposed: the thickness of 4.5m×4.3m and 4.8m×4.6m walls can be reduced from 0.74m to 0.49m, with reinforced wall columns and horizontal tension bars eliminated; the thickness of 6m×4.9m and 6.5m×4.9m walls can be reduced from 0.74m to 0.615m, with horizontal tension bars eliminated but reinforced wall columns retained.
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Intelligent acoustic emission diagnosis of micro-vibration faults in the hydraulic system of underground mining and excavation equipment in mines
Abstract:
As a core power equipment, the acoustic emission fault diagnosis of the hydraulic system in underground mines is confronted with engineering challenges such as strong mechanical vibration and noise interference and scarcity of fault samples. The existing diagnostic models generally have limitations such as insufficient classification accuracy and weak noise robustness. Therefore, this study integrates stacked denoising autoencoders, extrusion excitation channel attention modules, and bidirectional temporal convolutional networks to construct a collaborative fault diagnosis model. The aim is to achieve noise suppression and redundant information elimination through unsupervised feature purification, enhance the feature discrimination of fault-associated channels, and explore the temporal patterns of fault evolution. Experimental evaluation shows that the model has a correct rate of 96.4% after 30 rounds of training, a classification accuracy rate of 98.3% for all samples, and a recall rate of 96.7% for the initiation of early concealed fault microcracks. In a high-noise scenario with a signal-to-noise ratio of 5dB, the accuracy rate remained at 83.6%, and the classification accuracy rate reached 71.3% with 50 small samples. The entire diagnosis process took only 1.7 ms. In summary, this model demonstrates outstanding performance in complex noise environments, scarce sample conditions, and limited computing power equipment, providing reliable technical support for the early and precise identification and efficient early warning of faults in underground hydraulic systems in mines, and meeting the demanding engineering application requirements underground.
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Treatment and Environmental Assessment of Heavy Metal Pollution in the Historical Legacy Iron Tail Mining Area
Abstract:
Focusing on the prominent heavy metal pollution issues of historical legacy mines, a systematic environmental investigation and research on governance processes was carried out by taking a historical legacy iron tailings area in Hubei Province as the research case. On-site samples and tests revealed that chromium (particularly hexavalent chromium) and nickel were the main characteristic pollutants in the tailings sand of the mining area, as well as in the soil and sediments of the surrounding farmland and ditches. Their contents significantly exceeded the limits specified in the relevant environmental standards, posing prominent environmental and health risks. Through orthogonal experiments, the optimal process parameters for solidification/stabilization treatment were determined as follows: the mass ratio of the stabilizing agent to the solidifying agent was 1:4, the dosage of solidification/stabilization agents was 5.5% by mass relative to the tailings sand, and the curing period was 14 days. This parameter combination effectively reduced hexavalent chromium and immobilized heavy metals, and the leaching concentrations of the treated soil and sediment meet the Class III water quality requirements specified in “Standard for groundwater quality” (GB/T 14848-2017). Furthermore, an integrated process of “chemical reduction-flocculation-sedimentation” was adopted to treat the leachate, and neither chromium nor nickel was detected in the effluent after treatment, which effectively blocked the pollutant migration pathway. Compared with the traditional cement-based solidification method, this combined process reduced the cost by 23%, featured wide availability of reagents and simple operation, and was well adapted to the complex site conditions of the mining area. The research provides a systematic solution with both technical feasibility and economic efficiency for the pollution control and ecological restoration of similar historical legacy mines.
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Numerical simulation of coal mine goaf subsidence based on physics-informed neural network
Abstract:
Subsidence areas formed by underground coal mining can induce movement and deformation of overlying rock strata, leading to geological disasters such as surface collapse and landslides, which pose serious threats to people"s lives, property safety, and the ecological environment of mining areas. To accurately analyze the subsidence of goaf and the deformation patterns of overlying strata, numerical simulation methods have become an important research tool due to their efficiency and cost-effectiveness. In recent years, Physics-Informed Neural Networks (PINN), by integrating physical equations and data into the loss function, have demonstrated significant potential in solving both forward and inverse problems simultaneously. However, their practical applications still face challenges such as low accuracy, low training efficiency, and difficulties in handling non-uniform material problems. To address these issues, this paper proposes a single-hidden-layer feedforward neural network structure based on a domain decomposition strategy, combined with elastoplastic mechanical control equations, to construct a PINN model for goaf subsidence. Numerical simulation analysis of a 480-meter-deep goaf shows that the model can accurately predict the stress distribution of overlying strata, surface subsidence, and the evolution process of rock mass failure, providing new methods and technical pathways for the study of residual deformation in goaf areas.
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Preparation and admixture modification of magnesium oxysulfate cement based on low-grade magnesite
Abstract:
Magnesium oxychloride cement (M-MOS) was prepared using the calcined product of low-grade magnesite from Haicheng, Liaoning. The effects of different additives (citric acid, silicic acid, boric acid, tartaric acid, phosphoric acid and zinc sulfate heptahydrate) on the workability, compressive strength, and water resistance of M-MOS were investigated. Results show that additives significantly improved both the workability and mechanical durability of M-MOS. The ternary composite additive (citric acid + phosphoric acid + zinc sulfate heptahydrate) exhibited the best performance. It extended the initial setting time by 103.2%, increased the fluidity by 19.3%, enhanced the 28-day compressive strength by 118.9% to 56.7 MPa, and achieved a softening coefficient of 0.87. Acidic components released H+ to lower the pH and complex with Mg2+, thereby suppressing Mg(OH)2 formation and promoting the development of the high-strength 5·1·7 phase. Zn2? refined the microstructure through competitive precipitation, while PO43- participated in forming filling phases. The synergistic action of these components optimized the hydration process and product composition, effectively improving the overall performance of M-MOS. This study provides a feasible technological approach for the high-value utilization of low-grade magnesite and the preparation of high-performance M-MOS.
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Feasibility study on drone transportation scheme for mines in high-altitude mountainous areas
Abstract:
Due to the complex topographical and geological conditions, fragile ecological environment, and weak traditional transportation infrastructure in high-altitude mountainous areas, the development of the local mining economy has been severely restricted. To study the mine transportation scheme in high-altitude mountainous areas, the transportation of the Motuo stone pot mine in Xizang was taken as the research object. Considering its high value and fragility, a comparative analysis was conducted on drone transportation, cableway transportation, and belt conveyor transportation schemes in terms of technology, economy, safety, and environmental adaptability. The research results show that in the specific scenario of mine transportation in high-altitude mountainous areas, drone transportation can achieve point-to-point transportation with its good terrain adaptability, high timeliness, low cargo damage rate, and minimal environmental impact. Due to the limited production capacity of the stone pot (soapstone) mine, the drone transportation scheme is superior to the cableway and belt conveyor transportation schemes in terms of early infrastructure investment and unit transportation cost, exhibiting significant comprehensive advantages and becoming a preferred solution to the challenge of transporting raw materials from Motuo out of Xizang. However, the drone transportation scheme is significantly affected by airspace restrictions and meteorological conditions. The application process for airspace is lengthy and management is strict. Additionally, the meteorological conditions in this area are complex, requiring cautious flight.
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Research on the Opening of Fractured Rock Masses and Seepage Characteristics under Fluid-Structure Interaction
Abstract:
To investigate the stress and seepage variation characteristics in rock masses containing vertical fractures, assuming a constant normal stiffness of the fracture surface, the COMSOL Multiphysics coupling software was used to study the deformation, aperture changes, and seepage characteristics of fractured rock masses under different confining pressures and constant water pressure conditions. The study reveals: 1) Fracture aperture decreases during loading, with a more pronounced decline at higher confining pressures. During the unloading phase, the fracture aperture exhibits a rebound phenomenon, with the maximum aperture occurring at the junction of the fracture and the rupture surface; 2) Prior to rock failure, normal forces within the fracture plane manifest as compressive stresses, while forces along the shear plane exhibit tensile stresses. Upon reaching peak stress, normal stresses reverse to tensile stresses within the fracture plane, with maximum normal and shear stresses occurring at the fracture-fracture plane interface; 3) Prior to failure, the hydrostatic pressure within the fracture plane generally stabilises. When the fracture develops to the pre-existing fracture zone, the pressure within the fracture plane undergoes a sudden drop. The pressure from the fracture exit to the fracture failure plane decreases significantly compared to pre-failure levels. The aforementioned research provides valuable reference for predicting alterations in fracture water outburst pathways.
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Research and Application of Digital Twin-Based 3D Visualization Control System for Underground Mines
Abstract:
To address issues in the cross-regional operation of the KM mine project in the Democratic Republic of the Congo, such as delayed safety decision-making due to data latency and difficulties in sharing multi-source heterogeneous data, a visualized management and control system based on digital twin and 3D GIS technologies was proposed and implemented. The system constructs a three-tier architecture of “Field–Platform–Headquarters,” integrates VR for data interaction, and employs a timestamp-based asynchronous data acquisition and hierarchical dynamic update mechanism to consolidate geological, equipment, and transportation data. By integrating modules for geological management, mining monitoring, safety early warning, and automated operations, the system forms a full-process visual management framework. Serving as an effective support for remote centralized decision-making at the group headquarters, the system has been successfully deployed on-site, achieving a 50%–75% reduction in equipment failure rates, a 22%–28% improvement in transportation scheduling efficiency, and a 25%–35% reduction in typical safety incidents, providing a new paradigm for the digital transformation of the global mining industry.
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Process Mineralogy Research and Comprehensive Recovery Process Verification of a Low Grade Gold-Silver-Copper-Lead-Zinc-Iron Polymetallic Sulfide Ore
Abstract:
The low-grade polymetallic sulfide deposit located in western Yunnan contains gold (Au), silver (Ag), copper (Cu), lead (Pb), zinc (Zn), sulfur (S), and iron (Fe), with respective grades of 1.92 g/t, 41.34 g/t, 0.40%, 1.19%, 0.42%, 9.54%, and 34.92%. The content of the harmful element arsenic (As) is 0.22%. This ore type exhibits low concentrations of valuable elements, complex mineralogical characteristics, diverse mineral species, and highly uneven distribution, which pose significant challenges for comprehensive recovery. In this study, we utilized an AMICS automatic mineral analyzer, X-ray diffractometer (XRD), scanning electron microscopy (SEM), as well as chemical analysis and chemical phase analysis, to identify the primary mineral composition and relative content of the ore. Furthermore, we investigated the occurrence forms and states of Au, Ag, Cu, Pb, Zn, S, and Fe. Detailed analyses were conducted on the "genetic characteristics" of the main minerals, including their distribution relationships, size distributions, and dissociation characteristics. Based on these findings, we developed a processing flow that includes copper-lead mixed flotation followed by copper-lead separation, zinc-sulfur mixed flotation followed by zinc-sulfur separation, and low-intensity magnetic separation for iron. Closed-circuit tests of the entire process yielded the following results: a copper concentrate with a grade of 21.19% Cu, containing 52.40 g/t Au, 558 g/t Ag, and 5.26% Pb, achieving 74.50% Cu recovery; a lead concentrate with a grade of 74.66% Pb, containing 24.85 g/t Au, 1762 g/t Ag, and 2.67% Cu, achieving 82.54% Pb recovery; a zinc concentrate with a grade of 46.27% Zn, containing 1.33% Cu and 1.32% Pb, achieving 76.88% Zn recovery; a sulfur concentrate with a grade of 45.54% S, containing 3.0 g/t Au, 29.80 g/t Ag, and 44.33% Fe, achieving 81.91% S recovery; and a magnetite concentrate with a grade of 63.47% Fe, achieving 36.87% Fe recovery.
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Characterization of overlying rock development and stress distribution during mining of gently dipping coal seams
Abstract:
The deformation-movement-breaking of overlying strata in the mining process of gently inclined coal seams is the root cause of geological disasters such as large-scale roof cutting and water inrush. In order to study the evolution law and stress distribution characteristics of overlying strata under the influence of mining in gently inclined coal seam, taking WII02040502 fully mechanized mining face of Tunbao Coal Mine in Xinjiang as the engineering background, the physical similar material simulation test was used to study the caving and fracture development law of overlying strata during mining, and the influence of coal seam mining on the fracture development and stress distribution characteristics between overlying strata was analyzed. PFC3D numerical simulation is carried out, and compared with the results of physical similar material simulation test, the evolution law and stress distribution characteristics of overlying strata under mining of gently inclined coal seam are revealed. The research shows that:(1)With the progress of mining work, the overlying strata are affected and begin to slowly bend and sink, which in turn affects the collapse of the direct roof of the coal seam, and then there are more cracks in the overlying strata, and the basic roof also collapses.(2)With the progress of mining work, the closer to the working face position, the greater the stress value, and the more obvious the stress concentration phenomenon.(3)The caving zone of WII02040502 working face is about 22.12 m, the fracture zone is about 11.4 m, and the bending subsidence zone is about 39.62 m.
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Investigation and Evaluation of the Development and Utilization Level of Phosphate Rock Resources in Guizhou Province and Countermeasures for Major Problems
Abstract:
A systematic assessment of the exploitation and utilization efficiency of phosphate resources in Guizhou Province was conducted, based on a comprehensive survey of 19 phosphate mines. Guided by the Technical Guidelines for Survey and Evaluation of Mineral Resource Development and Utilization Levels in Guizhou Province and relevant national standards, a multi-dimensional evaluation framework was established. Through the integration of enterprise-reported data and field investigations, key metrics—including mining recovery rate, beneficiation recovery rate, and the comprehensive utilization rate of associated resources—were quantitatively analyzed. Results indicated that the overall utilization level of phosphate resources in Guizhou was graded as 'Moderate.' Specifically, 15.80% of mines were classified as advanced, 47.40% as moderate, and 36.80% as suboptimal, suggesting substantial room for improvement. Critical limitations in the current system were identified, notably the insufficient applicability of standard 'three-rate' indicators and inconsistent criteria for assessing associated resources. Consequently, the establishment of differentiated evaluation benchmarks tailored to regional resource endowments, the strengthening of data verification mechanisms, and the enhancement of technical management capabilities are recommended. These measures are essential for building a more scientific and robust evaluation system for phosphate resource development.
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Research on Autonomous Driving in Underground Mines Using Fusion SLAM
Abstract:
With the growing demand for unmanned driving systems in confined spaces such as underground mines, traditional SLAM algorithms face significant limitations in positioning accuracy, path planning, and real-time performance. In this study, SLAM algorithm based on the fusion of Ultra-Wideband (UWB) and LiDAR data was developed, and an unmanned driving system suitable for constrained mining environments was designed by integrating polar coordinate path planning and dynamic obstacle avoidance strategies. Field tests showed that the proposed system maintained a positioning error within 0.15 m under dynamic and complex conditions, and improved the path planning success rate by 23.6%, with significantly enhanced operational stability. The results indicated that the fusion of UWB and LiDAR effectively improved environmental perception and navigation accuracy in mine-oriented unmanned systems. The algorithm is structurally concise and deployable with flexibility, making it applicable to various mining scenarios. This study provides essential technical support and an engineering foundation for achieving intelligent and efficient unmanned transportation in mines.
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Determination of Bearing Capacity of Lunar Soil Simulant Based on Laboratory Loading Test
Abstract:
In the future, China will implement manned lunar landing missions, establish a permanent base on the lunar surface, and realize the exploitation and utilization of lunar mineral resources. To address the issue of determining lunar soil bearing capacity during lunar surface construction, this study proposes a method to deduce the allowable bearing capacity and settlement of lunar soil simulant under large-scale foundations by conducting small-scale laboratory loading tests. Firstly, plate loading tests were performed on lunar soil simulant with a compactness of 78% using circular loading plates with diameters of 6 cm, 8 cm, and 10 cm, respectively. The measured load-settlement (p-s) curves of the lunar soil simulant were obtained, and through curve fitting, the initial tangent modulus and ultimate bearing capacity were extracted. The tangent modulus method was adopted to establish the relationship between the tangent modulus of the lunar soil simulant and its initial tangent modulus, applied additional stress, as well as ultimate bearing capacity. Furthermore, based on the settlement calculation theory, the p-s curves under foundations of arbitrary sizes were calculated. Validation against the results of small-scale load tests demonstrated a good agreement between the calculated p-s curves and the measured ones. Secondly, the proposed method was employed to compute the p-s curves under large-scale foundations, and the allowable bearing capacity of large-scale foundations was comprehensively characterized by integrating the ultimate bearing capacity criterion and settlement control method. The analysis results of lunar soil simulant bearing capacity under large-scale circular and square foundations indicated that with the increase in foundation size, the allowable bearing capacity of the lunar soil simulant under both types of loading plates increased. Additionally, the allowable bearing capacity of the lunar soil simulant under square loading plates was higher than that under circular ones of the same size. It can be inferred from the calculated p-s curves that the settlement of the lunar soil simulant corresponding to the determined allowable bearing capacity meets the engineering requirements. According to the standard size of circular loading plates used in conventional loading tests, the allowable bearing capacity of the lunar soil simulant employed in this study was deduced to be 122 kPa. The proposed method for determining the allowable bearing capacity of lunar soil simulant provides a scientific approach and theoretical basis for the determination of lunar soil bearing capacity during the construction of lunar bases and the exploitation of lunar mineral resources.
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Experimental?study on optimization of phosphogypsum-based solid waste cementitious materials by lime and their application in backfill
Abstract:
?The cementitious material with high dosage of phosphogypsum(PG) has the disadvantages such as poor cementitious property and low strength. This study activate it by lime to improve the cementitious property of cementitious materials. This study used PG, steel slag, and blast furnace slag as raw materials for cementitious materials, lime as an activator, and tailings as aggregates to prepare backfill. The mechanical characteristics, pore characteristics, and microstructure of backfill materials under different lime dosages are explored. The results show that adding 2% lime can increase the strength of the backfill by up to 133.33% at 7d. Meanwhile, lime has a significant impact on pore of small pore sizes, especially on the fractal dimension of pores within 20-200nm. Finally, it is concluded that there is a clear functional relationship between strength and pore characteristics.
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Beneficiation Test Research on Surface Oxidized Ore from the Dadonggou Gold Deposit in Gaizhou City, Liaoning Province
Abstract:
Gold is a precious metal of high economic value, known for its excellent ductility, electrical conductivity, and stable chemical properties. It is widely used in jewelry, electronics, finance, and other fields.Given that the gold-bearing mineral is mainly sericite, and the gold dissemination particle size is fine (<0.037 mm) and occurs between grains, experimental research on chemical leaching processes (whole-ore agitation leaching and heap leaching) was conducted. Using the single-factor variable method, the effects of key parameters such as grinding fineness, pulp density, reagent dosage, and leaching time on the leaching efficiency were systematically investigated. The optimal process conditions were determined as follows: for whole-ore agitation leaching, under the conditions of grinding fineness (-0.074 mm content 97.10%), pulp density 30%, lime dosage 1.5 kg/t, leaching agent dosage 1.5 kg/t, lead nitrate (leaching aid) dosage 0.6 kg/t, and leaching time 36 h, the gold leaching rate reached 91.61%; for static immersion simulating heap leaching, under the conditions of liquid-solid ratio 1:1, cumulative lime dosage 2.27 kg/t, leaching agent dosage 1.6 kg/t, and leaching time 30 d, the gold leaching rate was 69.58%. The research results verify the applicability of chemical leaching for this type of fine-grained gold ore and provide a reliable technical basis for the design and parameter optimization of actual mining production processes.
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Variations of fracture seepage characteristics of coal true-triaxially hydraulic injected by ammonium persulfate
Abstract:
The permeability of coal directly affects the efficiency of gas extraction. The study investigates the fracture structure and permeability variation law of in-situ coal subjected to hydraulic injection of low-concentration ammonium persulfate by using the multi-phase and multi-field true triaxial dynamic seepage experimental system of coal-rock, combined with acoustic emission monitoring, ultrasonic testing and high-resolution image processing, and the influence mechanism of different liquid injection rates and hydraulic injection space was analyzed. The results indicate that for the experimental coal samples, a higher liquid injection rate leads to a shorter time required for coal fracture, a larger hydraulic injection space, and a lower coal fracturing pressure. Compared with water injection, ammonium persulfate injection results in fewer acoustic emission location points in the coal (indicating lower damage). However, the oxidative corrosion effect of ammonium persulfate can further enhance the development of fractures, achieving a better improvement in coal permeability. Among the samples, the one with a 4-hole fracturing pipe (the largest injection space)Sexhibits the most acoustic emission location points with the widest distribution. After hydraulic injection, the ultrasonic wave velocity of all five groups of coal samples decreases. Under the same conditions, a larger injection space leads to a wider range of coal fracture penetration and ammonium persulfate action, as well as a more significant increase in permeability. When the injection space is consistent, a lower injection rate results in better permeability improvement. The synergistic effect of ammonium persulfate"s oxidative corrosion and hydraulic injection-induced fracturing can promote the expansion of the coal fracture network, while the injection space affects the range and density of fracture expansion. These research results can provide theoretical guidance for the modification of seepage characteristics in low-permeability coal seams.
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Research on Dust Concentration Prediction Model for Shotcreting Operations Based on PSO-GA-BP
Abstract:
To achieve accurate prediction of dust concentration and diffusion patterns during roadway shotcreting operations, a dust concentration prediction model based on a BP neural network optimized by a hybrid algorithm combining Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) was constructed. The PSO-GA collaborative optimization mechanism was used to globally optimize the neural network parameters, overcoming the inherent defects of the conventional BP algorithm, such as poor convergence and a tendency to fall into local optima. Under the condition that the parameters of the shotcreting equipment are considered stable, and based on the on-site environmental parameters of shotcreting operations, humidity, temperature, distance from the working face, and wind speed were selected as input variables, while the total dust and respirable dust concentrations in three time periods (4-8 minutes, 22-25 minutes, and 40-44 minutes, representing the early, middle, and late stages) were taken as output variables to build the dust concentration prediction model. Through three analytical methods—correlation analysis, multiple linear regression analysis, and variance analysis—the sensitivity ranking of the selected environmental parameters affecting dust concentration changes in the roadway was determined as follows: distance from the working face > wind speed > humidity > temperature, and the area 10-20 meters from the working face was identified as a high-risk zone for dust concentration. Simulation and practical application results show that the PSO-GA hybrid optimization algorithm significantly improves the prediction accuracy and generalization ability of the BP neural network. The relative errors of the prediction results in the three time periods are all less than 5%, and the prediction accuracy is approximately 5% better than that of the current mainstream model, the Whale Optimization Algorithm (WOA-BP). This model provides reliable technical support for dust concentration prediction in underground mines under similar working conditions and has important practical value for ensuring the safety of mine operations.
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Research on the Benefits Evaluation of Geological Environment Restoration in Abandoned Mine Based on AHP-Entropy Method and Fuzzy Comprehensive Evaluation
Abstract:
Benefit evaluation aims to serve the prediction of the benefits of geological environment governance in abandoned mines and the assessment of the effectiveness of restoration, providing reliable decision-making support and effective supervision methods for restoration engineering practices. This paper, through the review and summary of domestic and foreign literature and the cluster analysis of relevant influencing indicators, combined with the triple bottom line theory and sustainable development theory, constructs a benefit evaluation index system for the geological environment restoration of abandoned mines from four dimensions: economy, society, ecology, and sustainable development. The AHP and entropy value method are used in combination to assign weights to the indicators, and the fuzzy comprehensive evaluation method is used to construct the evaluation model. The model is empirically applied in the geological environment restoration project of historical abandoned mines in Zhangjiakou City. The results show that the evaluation result is 89.684, and the restoration effectiveness level is good. The ecological and social benefit evaluation values are relatively high, indicating that the case project has generally achieved the restoration goals of eliminating hazards, improving the ecology, and enhancing functions. The sustainable development and economic benefit evaluation values are relatively low, and measures still need to be optimized from aspects such as improving maintenance systems and mechanisms, strengthening publicity and education, and implementing dynamic monitoring and supervision to further improve the comprehensive benefits of restoration. The application of the case proves that the evaluation index system and model are scientific and feasible, and can effectively evaluate the benefits of geological environment restoration in abandoned mines, providing reference for the benefit evaluation of similar projects.
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Research Progress on Flotation Separation Reagents for Cassiterite
Abstract:
Flotation of cassiterite is a critical step for the efficient utilization of complex mineral resources. This paper systematically reviews research progress in the development of cassiterite flotation reagents and the mechanisms of interfacial interactions. Based on the anisotropy of cassiterite crystal surfaces, it focuses on analyzing the distribution of active sites on the (110), (100), and (101) crystal planes and their synergistic adsorption mechanisms, revealing the coordination chemistry of metal ions (such as Pb2? and Fe3?) in interfacial activation. Regarding reagent systems, the paper reviews molecular design strategies for novel hydroxamic acid derivatives, phenylphosphonic acid-based collectors, and environmentally friendly amino acid-based collectors, indicating that functional group-directed modification can effectively enhance chelation selectivity toward Sn sites. Regarding mechanisms of action, combined reagents significantly enhance interfacial adsorption density through chelation and synergistic adsorption. For instance, hydroxamic acid-fatty acid combinations form multilayer adsorption structures, while cation-anion paired collectors reinforce both electrostatic and coordination interactions. Composite inhibitors like polyacrylic acid-lignosulfonate achieve precise suppression of calcium-magnesium gangue minerals via steric hindrance and specific adsorption. Future research should focus on establishing quantitative correlations between molecular structure, adsorption configuration, and flotation performance. Integrating computational chemistry methods will advance the rational design and industrial application of green, high-efficiency reagents.
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Research on a Data-Driven ISSA-MLP-CatBoost Model for Predicting Blasting Dust Concentration
Abstract:
To address the challenges in measuring blasting dust concentration in underground excavation faces, which consequently affects dust removal strategy design, this paper proposes a novel ISSA-MLP-CatBoost prediction model. Based on field measurement data of dust concentration, the model utilizes an Improved Sparrow Search Algorithm (ISSA) to optimize both a Multilayer Perceptron (MLP) and a Categorical Boosting (CatBoost) algorithm for dust concentration prediction. Data analysis was performed using the Pearson correlation coefficient (R), and the model's superiority was validated through comparisons with other models. Evaluation metrics including RMSE, MAE, MAPE, and R2 were employed to assess model performance, along with an in-depth analysis of various influencing features. The results demonstrate that the ISSA-MLP-CatBoost model achieved RMSE, MAE, MAPE, and R2 values of 0.784, 0.481, 4.754%, and 0.9939, respectively, with time and explosive charge identified as the primary influencing factors of dust concentration. This research establishes a high-precision prediction model for blasting dust concentration that can reliably forecast dust diffusion patterns, providing crucial theoretical foundation and decision-making support for developing scientific dust suppression measures in mines.
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Multi-scale optimization of YOLO for behavior state recognition of mining face workers
Abstract:
Coal mine production involves complex scenarios with numerous interconnected equipment, making workplace safety incidents frequent. Most accidents are directly or indirectly caused by human factors. Therefore, preventing violations such as improper operations, unauthorized work, and entry into hazardous areas is crucial for ensuring worker safety and reducing accidents. This study develops a deep learning-based method for underground personnel recognition and violation detection using Retinex and YOLOv5 optimized image processing. By integrating image enhancement techniques with object detection algorithms, the system achieves visual identification and assessment of underground personnel behavior. First, addressing challenges like uneven lighting and coal dust/mist interference, we propose an enhanced multi-scale Retinex algorithm that improves image clarity and natural color reproduction through multi-scale fusion and color restoration. Second, to tackle issues like dense equipment, complex backgrounds, and difficult detection, we construct a Retinex-YOLOv5 hybrid model. Finally, training on datasets including safety helmet usage patterns and on-site operational postures demonstrates over 95% accuracy in helmet recognition and 85% accuracy in general operational behavior detection, achieving precise identification of underground personnel""s safety gear compliance and behavioral patterns.
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Study on The Influence of Double Vent of Sidewall Cavity on Gas Explosion Characteristics of Tunneling Face
Abstract:
In recent years, coal mine gas explosion accidents have occurred frequently, posing a serious threat to industrial safety in production. To reduce losses caused by gas explosions, a rectangular pipeline is employed to simulate the roadway, with sidewall cavities and double vent ports of different positions and areas designed. Data on flame propagation and overpressure are collected using a high-speed camera and pressure sensors, and their mechanism of action is analyzed in combination with heat loss calculations. Results show that double venting through sidewall ports can significantly suppress flame propagation and reduce explosion pressure. Among the conditions tested, the optimal effect is achieved when the vent ports are located at 200/400mm with an area of 60×60mm2: the maximum flame propagation speed is reduced by 20.72% compared with the condition without a sidewall cavity, and the downstream overpressure is reduced by 41.04% compared with the condition without a sidewall. Proximal venting reduces energy accumulation through timely heat dissipation. Heat loss is positively correlated with the position of the vent port. An excessively large area leads to insufficient heat dissipation, which in turn affects the effect. This research provides a quantitative basis for parameter optimization of gas explosion venting devices in coal mines and has reference value for improving the ability to prevent and control underground explosion disasters.
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Scraper Conveyor Health Assessment Fusing a Hybrid Augmentation System and Dynamic Threshold
Abstract:
?? As a critical piece of equipment in mining production, the scraper conveyor often experiences performance degradation due to complex load variations and harsh operating conditions, making it essential to accurately monitor its health status. To address three core challenges in practical applications—sample imbalance, ambiguous health-state definitions, and feature redundancy—this paper proposes a health assessment method for scraper conveyors based on hybrid augmentation and dynamic thresholds.The model first designs a SMOTE-temporal hybrid data augmentation strategy, which effectively mitigates sample imbalance while preserving the temporal dynamics of the original data. Additionally, a health index feature fusion method is introduced to construct a more discriminative feature set and reduce redundancy. Furthermore, a dual-dimensional dynamic quantile threshold mechanism is proposed, which comprehensively utilizes health index and volatility features to dynamically and accurately delineate equipment states, thereby reducing false alarms caused by fixed thresholds. Finally, XGBoost multi-class classification is employed for graded health state assessment of the scraper conveyor.Taking the XGZ800/206 scraper conveyor from an open-pit mine in Xinjiang as the research object, the model"s effectiveness and alignment with actual working conditions are validated. The health status assessment accuracy reaches 98.34%, demonstrating the method’s validity and superiority. This approach enables precise characterization of the scraper conveyor’s health state and offers a new solution for mining equipment management.
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A New Model for the Conductivity of Rock Hydraulic Fractures under Three-dimensional Pressure
Abstract:
Hydraulic fractures are the main channels for fluid flow in unconventional reservoirs. Previous studies only considered the influence of proppant embedment-deformation under the closure pressure, while fractures are actually under the action of triaxial pressure. Considering the pressure parallel to the fracture surface, a new model for the conductivity of hydraulic fractures under triaxial pressure was established. The influence of the parallel pressure and triaxial pressure on the conductivity of pressure fractures was numerically analyzed. The results show that ignoring the horizontal pressure will underestimate the conductivity. Moreover, the larger the proppant radius, the fewer the proppant layers, the smaller the elastic modulus, the higher the Poisson"s ratio, and the smaller the pore pressure, the greater the influence of the parallel pressure. Under general reservoir conditions（σh1=σh2=80MPa, σv=70MPa, p=15MPa）, the conductivity of hydraulic fractures is underestimated by about 5%; under general experimental conditions（σr <30MPa, σz<30MPa, p<10MPa）, the conductivity of hydraulic fractures is underestimated by less than 2.5%.
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Research on status and geological environment restoration countermeasures of historical abandoned mines in Zhangjiakou city
Abstract:
The restoration of the geological environment in abandoned mines is an important approach to resolving the contradiction between mineral resource development and ecological protection, and it is also a significant measure to implement the deepening of the ecological civilization system reform. It plays a crucial role in building a beautiful China and improving the living and production environment and standards of the people. To better restore and utilize the historical abandoned mines in Zhangjiakou City, based on remote sensing monitoring, through methods such as data collection and on-site investigation, the current situation and characteristics of abandoned mines were statistically analyzed, common problems were summarized, and countermeasures and suggestions for geological environment restoration were proposed in combination with the local characteristics and conditions of the abandoned mines. The results show that: ① By the end of 2023, 475 un-restored historical abandoned mines were identified in various regions of Zhangjiakou City, covering an area of approximately 11.29 square kilometers. ② Zhangjiakou City is rich in mineral resources and has a long history of mining. However, due to the early extensive mining activities, about 685.52 hectares of terrain and landscape have been damaged, causing severe visual pollution and local ecological environment damage. ③ Currently, large-scale abandoned mine areas generally have five types of problems: severe and irreversible damage to the terrain and landscape, widespread geological disaster risks, prominent occupation and damage of land resources, significant damage to water resources and water ecology, and severe damage to soil and vegetation. These problems have caused relatively serious impacts on the geological and geomorphological conditions, land and water resources, the safety of residents" production and life, and biodiversity in the mining areas and their surroundings, and urgent restoration and governance are needed. ④ To carry out the restoration of the geological environment in historical abandoned mines in a targeted and high-quality manner, it is suggested to plan the work based on the working concept of "conforming to nature, systematic restoration, highlighting key points, adapting to local conditions, innovating mechanisms, and policy-driven", and propose an integrated interactive restoration model for abandoned mines with ecological restoration, industrial restoration, and value restoration as the framework. Explore the combination of geological environment restoration with industry and economic development to achieve the superimposed effects of economic, ecological, and social benefits, providing a reference for the restoration of the geological environment in abandoned mines and the promotion of green mine construction in China.
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Prediction and Application of Goaf Caving Risk Based on the Modified Protodyakonov Arch Theory
Abstract:
Addressing the problem of goaf caving severely restricting the safe and efficient mining of metal deposits, research on the goaf caving process is conducted and a prediction method for goaf caving risk is proposed. Considering the uneven pressure in the surrounding rock at the crown and abutments of the caving arch formed in underground mining of metal deposits, a theoretical analysis method is used to modify the Protodyakonov arch. A mechanical model of the caving arch under non-uniform load is established, deriving equations for the ultimate equilibrium arch and the natural equilibrium arch applicable to metal deposit goafs in stratified engineering geotechnical masses, and solving for their span and height. Based on the mechanical analysis of rock blocks above the arch, the caving stages are divided using the spans of the natural equilibrium arch and the ultimate equilibrium arch, proposing a method for predicting goaf caving risk. Using experimental methods, with the goaf of a specific iron mine as the engineering background, the spans and heights of its ultimate equilibrium arch and natural equilibrium arch are calculated. On this basis, Similar simulation experiments on goaf caving with different spans are conducted. The results demonstrate that the experimentally observed collapse process is in strong agreement with theoretical predictions, verifying the reliability of the established model and prediction method. Based on this, the caving risk of the iron mine goaf is predicted. The research conclusions indicate that the established modified caving arch model and risk prediction method can effectively predict the caving process and risk of goafs, providing a theoretical basis and practical means for the quantitative stability assessment of goafs and the prevention and control of caving disasters.
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Research on the Technological Innovation and Sustainable Development of Converting an Open-Pit Iron Mine to Underground Mining
Abstract:
After metal mines transitioned from open-pit to underground mining, research was conducted on joint drainage systems, pillar thickness design, and new types of filling cementitious materials to address issues such as water backflow, pillar safety, and tailings accumulation associated with the transition. The study results show that the mine innovatively established an integrated system for surface dewatering–underground centralized drainage–plant reuse and water resource recycling, which can save a total of 3.684 million yuan in underground drainage and new water costs. By comprehensively applying the engineering analogy analysis method and the limit equilibrium analysis method, the pillar thickness was reduced from 20m before the study to 16m, increasing the ore amount by 105,100.8 tons and generating an additional benefit of 7.0828 million yuan over five years. At the same time, a new cementitious filling material suitable for ultra-fine total tailings, which can replace cement, was developed, achieving high-strength, low-cost total tailings cemented backfilling and 100% tailings recycling, reducing tailings pond land acquisition costs by 35.686 million yuan and annual backfilling costs by 12.96 million yuan. Through this research, multi-objective optimization of resource utilization, safety assurance, and ecological coordination was achieved, providing other mining enterprises undergoing mining method transformation with replicable and promotable technical approaches and practical models.
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Study on Multi-level and Multi-point Cooperative Mining Technology for Inclined, Extra-thin and Broken OreBody
Abstract:
The 414 ore body in a Yunnan tin mine is characterized by its steep dip, extremely thin thickness, and fractured nature. Originally mined using the sublevel caving method with top-down retreat mining by levels, it could no longer meet the growing production demands. A transition was therefore proposed to shift to a multi-level, multi-face synchronized filling mining mode, accompanied by research on filling mining methods tailored to fragmented ore bodies, to ensure the mine achieves its planned production targets.Incorporating site-specific technical conditions, an innovative "sublevel drilling and subsequent filling stoping method" was developed, featuring the advanced construction of a false roof for the current level at the bottom pillar of the upper level. Based on the ore body characteristics of a typical level in section 414, mining zones were delineated, with distinct stoping processes, extraction sequences, stope layout parameters, and filling body strengths designed for each zone. This comprehensively addressed the key technical challenges of multi-level, multi-face coordinated mining in fractured ore bodies. Numerical modeling confirmed the safety and reliability of the approach. To mitigate the potential risk of a hanging roof formed by the primary step filling during secondary step mining, the solution of installing anchor cable support on the side slopes of secondary stopes during primary step extraction was introduced.Implementation results demonstrate that the optimized approach enabled the 414 ore body to achieve the targeted production rate of 500 t/d. Both dilution and loss rates were reduced compared to the original method. Underground operational safety was significantly enhanced, with no occurrences of roof collapse.
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Research on Methane Concentration Prediction in Roadhead Areas Based on an Improved KAN-iTransformer
Abstract:
The tunneling face is a high-risk area for gas accidents during coal mining operations. Addressing the strong nonlinearity and spatiotemporal dynamic correlations in methane concentration variations, this paper proposes the KAN-iTransformer prediction model, which integrates Kolmogorov–Arnold Networks (KAN) with an improved Inverted Transformer (iTransformer). First, a feature dataset for gas concentration prediction was constructed through data preprocessing and Spearman correlation coefficient analysis. Then, treating the complete variable sequence as labels based on the inverted Transformer architecture, a graph attention mechanism was introduced to explicitly model the spatial topological correlations within the sensor network, enhancing the effective modeling of dynamic dependencies between sensors. Further, KAN's learnable activation function replaces traditional linear weights, improving the model's ability to represent complex nonlinear relationships among multi-source monitoring parameters. Finally, a hierarchical response mechanism integrating point prediction and interval estimation is proposed, enabling proactive dynamic tiered responses to methane overlimit risks. Field data experiments demonstrate that the model achieves a mean squared error (MSE) of 0.000307, a mean absolute error (MAE) of 0.012921, and a mean absolute percentage error (MAPE) of 2.321373 in single-step prediction. outperforming both iTransformer and Transformer baseline models. In multi-step predictions, the MSE was 0.000913, representing reductions of 62.4% and 80.1% compared to baseline models, demonstrating superior long-term forecasting capabilities. This effectively achieves precise prediction and dynamic early warning of methane concentrations in tunneling workfaces.
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Research on Hierarchical and Clustered Prediction Algorithms for Open-Pit Mine Road Travel Time
Abstract:
Accurate travel time prediction of autonomous haul trucks is a critical component of intelligent dispatching and transportation optimization in open-pit mines, as its precision directly affects production efficiency and operational safety. To address the low prediction accuracy of global models caused by feature entanglement under complex road conditions, a hierarchical and clustered travel time prediction framework (HDFM) is constructed. The framework performs feature abstraction and multi-granularity clustering to identify road types, and builds targeted prediction models within each subspace to capture the travel patterns of different road categories in a hierarchical manner. A soft-membership fusion strategy is further introduced to achieve smooth prediction across categories at the global level. Experimental results show that, compared with a single predictive model without road classification, the optimal model groups achieve mean absolute errors (MAE) of 0.22% and 1.95% under unloaded and loaded conditions, respectively. The framework maintains high prediction accuracy and stability under complex road conditions, providing an alternative technical route for travel time modeling of autonomous haul trucks in open-pit mines and methodological reference for performance prediction in other multi-modal complex systems.
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Research on the Synergistic Rock-Breaking Effect and Application of Fracturing and Blasting in Hard Rock Roadways
Abstract:
To address the traditional safety and damage control issues in the excavation of hard rock tunnels, a technology of hydraulic fracturing and blasting combined for rock breaking was proposed. Taking the -375m horizontal rock tunnel of Li Lou Iron Mine as the engineering background, the rock fragmentation process under two hole arrangement methods and four hole spacings was simulated based on the PFC2D model. The laws between crack evolution and stress field response were analyzed. The results showed that the hole spacing significantly affected the combined effect of hydraulic fracturing and blasting for rock breaking. When the hole spacing was 0.4m, the cracks developed uniformly and the stress field distribution was reasonable; when the hole spacing was 0.6m or more, the combined effect weakened. Based on the uniformity of crack extension, regional characteristics and fractal dimension, 0.4m was determined as the optimal hole spacing, and the diamond-shaped hole arrangement performed better. The field test verified the effectiveness of the optimized parameters, and the PFC2D simulation provided support for the technical feasibility.
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Study on Stability and Sensitivity of Buckling Failure of Steeply Inclined Rock Slopes Under Multi-Factor Coupling Effect
Abstract:
Aiming at the common buckling failure problem of steeply inclined rock slopes, this study conducts stability analysis and sensitivity research on influencing factors under the coupling effect of multiple factors including earthquake, rainfall, and freeze-thaw. The failure characteristics of the slope were clarified through field geological surveys. Based on basic assumptions such as coordinated deformation and small deformation, the slope mechanical model was generalized, the differential equation of the surface rock layer was established, and the calculation formula for the safety factor of buckling failure was derived by combining the energy balance principle. According to geological survey data and relevant specifications, the reference values and value ranges of 10 influencing factors (e.g., slope angle, elastic modulus, and rock layer thickness) were determined. An L54 (310) orthogonal test design was adopted to construct multi-condition calculation schemes, and variance analysis was used to identify the sensitivity ranking of each factor. Additionally, single-factor analysis was performed to reveal the influence law of key factors on the safety factor. The results show that under multi-factor coupling, the sensitivity of factors affecting the stability of steep slopes from high to low is as follows: rock layer thickness (h) > elastic modulus (E) > rock unit weight (γ) > horizontal seismic action coefficient () > slope angle () > groundwater level height (Zw) > cohesion of weak layer (c) > internal friction angle of weak layer () > freezing depth (l) > ice pressure on fracture surface (f). Increasing rock layer thickness and elastic modulus can significantly improve the slope safety factor (the slope is stable when rock layer thickness > 10m and elastic modulus > 32GPa), while increasing rock unit weight, horizontal seismic action coefficient, and slope angle leads to a decrease in the safety factor. During the rainfall infiltration process, the slope toe exhibits higher sensitivity to rainfall impact. As the rainfall infiltration duration increases, the influence range of pore water pressure expands towards the interior of the slope, and the slope instability phenomenon intensifies. The research results can provide a theoretical basis and technical support for the prevention and control of buckling failure and optimization of engineering design of steeply inclined rock slopes.
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Evaluation of Ecological Restoration Benefits of Limestone Mines in Jinan City Based on Combination Weighting and Matter Element Extension
Abstract:
The ecological restoration of mines is the key to achieving the "dual carbon" goal and regional sustainable development. Scientific evaluation of the benefits of different ecological restoration models for mines is of great practical significance for the selection of restoration models and the determination of governance technologies. Therefore, a 14 index evaluation index system for the ecological restoration benefits of limestone mine in Jinan City, considering four aspects: ecology, economy, society, and security. Based on the combination weighting of game theory and the principle of matter element extension, a method for evaluating the ecological restoration benefits of limestone mine in Jinan City was proposed. In May 2025, five typical restoration mines were selected in Jinan City for field research and evaluation, focusing on five different ecological restoration models: vegetation greening, land reclamation, construction land, landscape reconstruction, and natural restoration. The results show that: (1) The weight of the ecological restoration benefit criteria layer for limestone mine in Jinan City, in descending order, is safety benefit, ecological benefit, social benefit, and economic benefit; (2) In the constructed indicator system, the top four evaluation indicators that affect the weight are the construction length of retaining walls, the number of employed people, the income of model products, and the soil consolidation volume of vegetation roots; (3) Among the five ecological restoration modes, landscape reconstruction mode has the best restoration benefits, followed by vegetation greening mode and construction land mode. The restoration benefits of land reclamation mode is moderate, and the restoration benefits of natural restoration mode is poor. The research methods and results can provide references for the evaluation of limestone mine restoration benefits and mode selection in Jinan City.
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Experimental Study on Mineral Processing of Oxidized Lead-Zinc Ore in Xinjiang
Abstract:
Aimed at these problems including high content of carbonate gangue, high oxidation rate and severe mudization of oxidized lead-zinc ore of Xinjiang, detailed experimental research on mineral processing technology was carried out. When the raw ore contains 6.90% lead and 6.06% zinc, and the oxidation rates of lead and zinc reach 81.30% and 95.05% respectively, the separability of oxidized lead-zinc minerals was improved by using compound phosphate as a carbonate gangue inhibitor. The process flow of lead oxide-sulfur bulk flotation-flotation desliming-zinc oxide flotation was adopted, and full closed-circuit process test obtained the indicators of lead concentrate with lead grade of 50.32%, zinc content of 3.76%, lead recovery rate of 80.84%, zinc oxide concentrate with zinc grade of 35.73%, lead content of 4.21%, and zinc recovery rate of 75.62%. The efficient flotation recovery of this lead-zinc oxide ore has been achieved.
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Design and Implementation of an Intelligent Resource Evaluation System for Closed/Abandoned MinesBased on an Adaptive Analytic Hierarchy Process
Abstract:
Under the dual drivers of supply-side structural reform in the coal industry and the "dual carbon" goals, the resource development and utilization of closed/abandoned mines have become increasingly urgent. Accurately assessing their resource potential and utilization feasibility is a critical step toward achieving this objective. Currently, various methods such as Analytic Hierarchy Process (AHP), fuzzy comprehensive evaluation, and game theory have been introduced into related research. However, these methods generally suffer from significant subjective influence, poor dynamic adaptability, and low evaluation efficiency, leading to inadequate resource assessment outcomes for closed/abandoned mines and failing to provide guidance for precise development. Based on this, guided by the synergistic concept of "energy-oriented, resource-oriented, and function-oriented" utilization, a multi-dimensional evaluation index system with a three-tier structure of "target layer - criterion layer - indicator layer" was constructed. By comprehensively utilizing algorithms such as AHP, LightGBM, and Isolation Forest, an intelligent model for dynamic optimization and consistency testing of weights was developed. Using Java and based on the Vue.js and Spring Boot frameworks, along with tools such as MySQL, Redis, Apache POI, and Docker, an intelligent evaluation system for resources of closed/abandoned mines based on an adaptive Analytic Hierarchy Process was developed. This system realizes data import, AHP calculation, and result visualization, overcoming the shortcomings of static weights and excessive manual intervention in traditional methods. A case study based on the actual conditions of Longdong Coal Mine demonstrates that the system can accurately reflect the resource characteristics of the mine and exhibits good practicality. The research results provide a replicable technical pathway for the intelligent evaluation of resources in closed/abandoned mines and offer a reference for the sustainable development of national mineral resources.
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Research on the Mechanical Characteristic Laws of Self-Repairing Grouting Materials Modified by Nano-Silica
Abstract:
Grouting and sealing is a crucial step in coal seam gas drainage. The properties of the grouting material determine the sealing quality. Self-healing grouting materials are an effective solution to the problem of re-occurring cracks after grouting. However, the addition of self-healing agents is in conflict with the mechanical properties of the grouting material. Therefore, nano-SiO2 was used to modify the self-healing grouting material. The mechanical properties of the modified grouting material were improved by nearly three times, effectively delaying the formation of re-occurring cracks. It could complete the self-healing of 0.69mm cracks within 3 days. The unique nano-scale characteristics, high specific surface area, and chemical activity of nano-SiO2 exert multiple effects during the cement hydration process: filling effect, accelerated hydration, pozzolanic reaction, and microstructure optimization, which have a positive promoting effect on both the matrix of the grouting material and the self-healing effect. The research results can provide a basis for optimizing the mechanical and self-healing properties of cement-based self-healing grouting sealing materials and lay a foundation for the development of grouting materials.
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Study on the Reasonable Strength of Filling Body and the Stability of Pillar Recovery in a Fluorite Mine Goaf
Abstract:
The treatment of mined-out area is very important for the recovery of residual ore. It is the key premise to ensure the safe and economic recovery of subsequent pillars to select the appropriate strength of filling body to backfill the mined-out area, support the surrounding rock of mined-out area by filling body, inhibit the deformation of rock strata, and avoid the instability of pillars in advance due to the concentration of stress. Aiming at the problem of early residual goaf and residual pillar in a fluorite mine, this paper chooses the shallow hole shrinkage and subsequent filling mining method suitable for medium-thick ore body to recover the pillar, and preliminarily determines the filling strength range of 1.06 ~ 2.08 MPa through theoretical empirical formula. Combined with the numerical simulation method, the strength of the final filling body is determined. The results show that when the strength of the filling body is 2.0 MPa, it can effectively limit the stress concentration at the top and bottom
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Development and Application of an Autonomous Driving System for Underground Electric Scrapers
Abstract:
With the rapid advancement of autonomous driving technology, its application domains are continuously expanding, and unmanned driving in mines has emerged as a key direction in the development of intelligent mining. To address the challenges of complex underground environments, high labor intensity, and elevated safety risks, this paper designs and implements an unmanned driving system for underground electric scrapers, integrating autonomous driving with remote-control technology. The system operates in the mode of “remote-controlled loading, autonomous transportation, and automatic unloading, thereby enabling fully unmanned scraper operations in roadway environments. Field tests demonstrate that the maximum lateral tracking error of the system remains within 0.25 m during operation. In terms of speed performance, the scraper achieves a maximum straight-line driving speed exceeding 10 km/h in autonomous mode, while the maximum turning speed reaches 6.9 km/h, the location loss probability is about 0.11%. Additionally, the remote-control communication delay is maintained below 5 ms. The research results verify the stability and practicability of this system in the mine underground environment, which can reduce the labor intensity of miners and improve the working environment.
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Key Factors Influencing Natural Recovery in a Typical Abandoned Manganese Mine of Hunan Province
Abstract:
Nature-based Solutions (NbS) are crucial for the ecological restoration of mining areas. To identify the key environmental factors influencing the natural recovery of abandoned manganese mines, this study focused on a typical site in Renyi Town, Leiyang City, Hunan Province. Through field vegetation surveys and soil sampling, the relationships between soil physicochemical properties and plant community structure were systematically investigated using correlation analysis, principal component analysis (PCA), and redundancy analysis (RDA). The results indicated that: (1) Soil available phosphorus, organic matter, gravel content, and sand content exhibited high coefficients of variation, which were key factors contributing to the variation in vegetation restoration. (2) Soil organic matter showed highly significant positive correlations with total nitrogen, hydrolyzable nitrogen, and available potassium, identifying it as a core indicator for assessing overall soil fertility. (3) The plant community was species-poor, primarily composed of pioneer species such as Miscanthus sinensis, Pteridium aquilinum, Mallotus apelta, and Bothriochloa ischaemum. Ecological succession was interpreted as following a non-linear sequence: "simple pioneer community → species-rich intermediate community → complex late-successional community". (4) Redundancy analysis revealed that organic matter was the primary environmental factor driving vegetation community structure, followed by gravel content and pH. In summary, the soil factors influencing natural restoration of the mining area, ranked in descending order of impact, are as follows: organic matter, clay content, gravel content, pH, water content, and available phosphorus. The findings provide a clear theoretical basis for precise ecological restoration in similar mining regions.
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Triaxial loading tests and damage characteristics of sandstone under the influence of hydraulic coupling
Abstract:
The progressive damage and failure mechanism of sandstone under hydraulic coupling is a key scientific issue for revealing the failure law and deterioration process of the floor under confined water conditions. To this end, triaxial compression tests under different confining pressures and pore water pressures were conducted, and the evolution characteristics of fractures were quantitatively analyzed by the fracture volume strain method. The results show that the full stress-strain curve of sandstone can be divided into five stages: crack compaction, elasticity, stable propagation, unstable propagation, and post-peak failure, and the threshold stresses (closure stress, initiation stress, dilation stress, peak stress, and residual stress) increase linearly with confining pressure, but have no significant correlation with the peak stress ratio. The existence of pore water pressure significantly reduces the elastic modulus, Poisson"s ratio, internal friction angle, and cohesion, accelerates crack propagation, and causes the boundary degradation of the strength criterion. Based on the effective stress principle and statistical damage theory, a damage constitutive model of sandstone under hydraulic coupling was established, and the Weibull distribution was introduced to describe the strength dispersion of micro-units. The model parameters were verified by fitting the test data, and the mean correlation coefficient was 0.9236, which can accurately reflect the mechanical response law of sandstone under hydraulic coupling. The research results can provide theoretical support and mechanical test basis for the stability evaluation of rock strata in the floor water prevention and control of mines.
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Study on the deformation mechanism and management measures of a submerged slide zone in DRC
Abstract:
The study of slope deformation mechanism is the basis and key to formulate reasonable management measures. In order to formulate the management plan for a submerged slide zone in DRC, a site investigation and drilling survey were carried out in the deformed area to analyze the formation process of the slip surface of the submerged slide zone, and based on the investigation results, the deformation mechanism of the submerged slide zone was analyzed in detail, and finally a comprehensive slope cutting and reduction plan with slope cutting and load reduction, large-diameter antiskid piles, and soil nail walls was formulated to achieve good results on site. Finally, the management plan of local reinforcement was formulated, and good results were achieved in the field. Results: The formation of the slip surface is based on geological action, and under the influence of open-pit mining, the slip surface is continuously extended downward and may eventually be connected to form a whole slip surface. The mechanism of slip formation in the submerged slip zone is divided into three stages: push-type sliding produced by unloading rebound, pull-type sliding produced by lower excavation, and overall push-type sliding developed by the slip surface. Based on the formation mechanism of the submerged slip zone, the joint management measures of slope reduction, soil nail wall and anti-slip pile were formulated, and the reasonableness of the management scheme was verified through calculation and analysis. The research results provide reference for the research of similar soft rock slope management measures in open pit mines.
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Mechanical Response Characteristics and Numerical Simulation of Backfill in Deep Stopes
Abstract:
To reveal the mechanical response of backfill under high geostress and mining-induced disturbances in deep stopes, the 8th-level stope of the Jiaojia Gold Mine was selected as a case study. Pressure cells and settlement gauges were installed to obtain the stress and deformation data of the backfill during different mining stages. A three-dimensional numerical model of the deep stope backfill was established to investigate the stress redistribution and deformation evolution under multi-step stoping conditions. The results indicate that the stress within the backfill exhibits a staged fluctuation during mining disturbances, with the vertical stress showing the most pronounced variation. The stress variation during the blasting stage is approximately 0.02 MPa, suggesting that the backfill mainly experiences elastic deformation. During the stoping process, the internal monitoring points generally record higher stress values than the external points, and the vertical direction shows the greatest stress increment. Numerical simulation results demonstrate a distinct interlayer stress-transfer behavior, in which the stress is transmitted upward and the deformation concentrates in the early-filled layers before stabilizing in later stages. These findings elucidate the stress–deformation evolution of backfill in deep stopes and provide a theoretical basis and technical reference for the design and stability control of deep-mine backfilling systems.
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Sudden change analysis and optimization measures of slope stability energy under seismic conditions
Abstract:
To analyze the energy evolution patterns of open-pit mine waste dumps under seismic conditions and establish energy-based instability criteria for slopes, this study integrates the cusp catastrophe theory with the energy theory of open-pit mine waste dumps. A dissipative energy catastrophe instability model with slope dissipation energy as the state variable was developed. Using the south waste dump of the Dasuji molybdenum mine as an engineering case study, FLAC3D finite element analysis was employed to examine the dissipation energy evolution patterns and conduct catastrophe analysis across four slope profiles. Optimization measures were then proposed for the south waste dump slope. The results indicate that most characteristic dissipation energy values of the south waste dump slope profiles were below 0, rendering them prone to instability under seismic loading—a finding consistent with field observations. Based on dissipation energy evolution characteristics, optimization measures including "slope surface reinforcement + stacking optimization + monitoring and early warning" were proposed. Subsequent numerical simulations and field monitoring confirmed that the optimized slope exhibited significantly enhanced deformation resistance and maintained stability. These findings provide valuable references for preventing slope instability in mine waste dumps.
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Numerical Study on the Instability Mechanism of Lateral Slopes with Discrete Fractures Induced by Caving Mining
Abstract:
Caving mining induces progressive surface subsidence, significantly increasing the potential for instability of adjacent lateral slopes. Based on the on-site geological conditions and actual engineering background of the mining area, a FEM-DEM coupled numerical model incorporating a discrete fracture network was established to analyze the stress distribution and deformation evolution of lateral slopes with complex fracture structures under caving mining disturbances, revealing the instability mechanisms of the lateral slopes. The results indicate that slope deformation evolves through three stages: expansion of the mining-affected zone, localized collapse at the slope toe accompanied by surface spalling, and fragmentation and disintegration of the slope mass. During ore drawing, the horizontal displacement of the slope rock mass is most sensitive to mining-induced disturbances; horizontal stress in the upper slope gradually decreases while vertical stress increases, and significant stress concentration occurs in the slope toe, with frontal slope failure inducing abrupt stress changes in the rear slope. Under the combined effect of lateral unloading and gravity-induced unloading, anti-dip fractures experience tensile failure and dip-oriented fractures undergo shear failure, resulting in a step-like tensile–shear–tensile overall failure pattern in the slope. The findings provide valuable insights into the mechanisms of lateral slope instability induced by underground mining.
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Research on the Failure Characteristics of Surrounding Rock with Cracks in Deep Tunnels
Abstract:
The surrounding rock of deep tunnels often contains non penetrating cracks and is in a true triaxial high stress environment. After excavation, it faces a single-sided free boundary condition, which seriously affects the stability of the surrounding rock. This study systematically investigated the failure mechanism and acoustic emission evolution characteristics of fractured surrounding rock in deep tunnels through true triaxial single-sided free loading experiments. The experimental design covers three types of flaw inclination angles of 0°, 45° and 90°, as well as three types of flaw depths of 50 mm, 65 mm, and 80 mm. Combined with acoustic emission monitoring, the influence of crack parameters on the mechanical properties, crack propagation modes, and acoustic emission response of the specimens was analyzed. The results indicate that the 0° fracture angle specimen exhibits higher acoustic emission counts and cumulative energy during the failure process, as its shear slip is accompanied by multiple microcrack accumulations, while the 90° flaw specimen is dominated by tensile fracture, with acoustic emission activity more concentrated in the unstable fracture stage, the 45° flaw specimen exhibits a mixed failure mode of shear and tension. In addition, σ2 will suppress the crack development at the crack tip, resulting in mainly layered failure of the specimen, exhibiting zoning characteristics of near free surface splitting and far-field shear. This study reveals the failure mechanism and acoustic emission response law of fractured rocks under true triaxial single-sided free space conditions, clarifies the control effect of fracture inclination and depth on the failure mode, and provides experimental basis and theoretical support for the stability assessment and disaster prevention of deep engineering surrounding rocks.
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Research Progress in Safety Monitoring and Early Warning Technology for Open-Pit Mine Slopes and Platform Development
Abstract:
Frequent occurrences of geological hazards on open-pit mine slopes have highlighted the limitations of traditional monitoring methods in terms of real-time performance, coverage density, and intelligent early warning. Based on existing research achievements in slope safety monitoring and early warning, current deficiencies and critical issues requiring urgent resolution are systematically summarized. By integrating Internet of Things (IoT), cloud computing, big data, and artificial intelligence technologies, a multi-dimensional and multi-source collaborative sensing network spanning air, space, surface, and subsurface domains is constructed. An intelligent slope monitoring and early warning platform for open-pit mines is developed to facilitate intelligent diagnosis of slope stability and trend prediction. Through a tiered warning mechanism and a visual decision support system, precise risk identification and emergency coordination are achieved. Practical applications demonstrate that the platform significantly enhances proactive perception and advanced early warning capabilities for slope risks, thereby providing technical support for intrinsic safety in open-pit mines and the advancement of intelligent mining construction.
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DISCUSSION ON MIGRATION EVOLUTION LAWS AND ZONING MIGRATION BEHAVIOR OF OVERLYING ROCKS IN COAL FACE WITH LARGE INCLINATION AND LARGE MINING HEIGHT
Abstract:
Mining in the fully mechanized working face with large inclination and large mining height is difficult. During the mining process, the movement and evolution process of the stope rock strata has not yet been fully grasped. The mine pressure appears more severe and the roof is difficult to control, which seriously threatens the lives, health and safe production of operators. To this end, taking the 1907 high-dip and large-mining-height working face of Changcheng No. 2 Mine as the research background, 3DEC numerical simulation software and similar simulation experiments were used to study the migration and evolution laws of overlying rocks in the high-dip and large-mining-height coal seam working face. The research shows that: (1) When the mining height is 4m and the coal seam inclination is 35°, 40° and 45° respectively, the advancing length of the working face is 220m, and the height of the cave-out rock layer in the goaf is basically about 16.5m, and the height of the cave-out rock layer is basically unaffected by the coal seam inclination. The maximum heights of fractured rock layers are 55.9 m, 58.2 m and 62.1 m respectively. With the increase of coal seam inclination, the height of fractured rock layers gradually increases. (2) When the coal seam inclination angle is 40° and the coal seam thickness is 4m, 5m and 6m respectively, and when the working face advancement length reaches 220m, the heights of the collapsed rock layers in the goaf are 16.5 m, 21.0 m and 25.5 m respectively; the maximum heights of the fractured rock layers are 58.2 m, 68.6 m and 79.8 m respectively. As the thickness of the coal seam increases, the height of the fractured rock layers gradually increases. (3) As the working face gradually advanced, the overlying roof experienced a change trend of damage in the middle and upper regions-oblique extension on both sides of the upper end-and development of the lower tendency. The collapse characteristics changed from "inverted triangle" to "inverted t*zoid", and the t*zoid area gradually increased. (4) Discuss the migration adjustment forms of overlying strata in large dip coal seam: multi-directional movement adjustment, rotation movement adjustment, vertical movement adjustment, and horizontal movement adjustment. The rock mass migration forms in the middle and upper roof mainly include multi-directional movement adjustment and rotation movement adjustment, and the rock mass migration forms in the lower roof mainly include vertical movement adjustment and horizontal movement adjustment.
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The theoretical analytical solution of soil pressure and its influence range under supporting conditions in foundation pit is considered
Abstract:
Regarding the issue of earth pressure calculation in foundation pit engineering, this paper establishes an analytical method for earth pressure and analyzes the effects of various influencing factors. Based on the fundamental assumptions of Coulomb's earth pressure theory, a calculation model for earth pressure is developed by comprehensively considering factors such as wall-soil interface friction, soil shear strength parameters, excavation depth, and strut axial forces. Quantitative formulas for earth pressure induced by excavation disturbance and its influence range are proposed. Through sensitivity analysis of influencing factors, the order of impact of various factors on the influence range under conditions with and without steel struts is clarified. The variation patterns of the influence range under different working conditions and excavation stages are investigated and comparatively validated. The results show that the distribution patterns of earth pressure along the depth are consistent between the two, verifying the correctness of the model. Sensitivity analysis indicates that, in the absence of struts, excavation depth has the most significant effect on the influence range, whereas after installing steel struts, strut axial force becomes the primary controlling factor. The model presented in this paper can effectively quantify and analyze the earth pressure distribution and disturbance influence range during the excavation of the 110kV substation foundation pit, a supporting project of an energy development base in Hefei, Anhui. It subsequently provides a theoretical reference for the design and analysis of foundation pit engineering in related energy and mineral resource development infrastructure projects.
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Effects of Combined Dynamic and Static Damage on the Acoustic Emission Kaiser Effect in Marble: An Experimental Study
Abstract:
With the progression of mining activities into deeper strata, the stability of surrounding rock masses is increasingly compromised by the combined influence of high in-situ stresses and frequent dynamic disturbances. This study systematically examines the damage evolution and fatigue mechanical behavior of marble under such conditions through a series of combined dynamic-static and cyclic loading-unloading tests. Specimens, obtained from typical mine roadway surroundings, were subjected to varying levels of axial static stress (0, 15, 30, and 45 MPa) and impact velocities (7 m/s and 9 m/s) to replicate the complex stress paths characteristic of deep mining environments. Damage progression was characterized using nuclear magnetic resonance (NMR) pore structure analysis and ultrasonic wave velocity measurements. The results demonstrate that combined dynamic-static loading significantly modifies the pore structure of marble. As static stress and impact intensity increase, the pore system evolves from isolated voids into interconnected networks, accompanied by a nonlinear accumulation of damage. Under low static stress and weak dynamic disturbance, the rock exhibits increased fatigue strength, attributable to compaction effects. In contrast, high static stress coupled with strong disturbance promotes the formation of interconnected fracture networks, leading to a marked decrease in fatigue strength. During cyclic loading-unloading, a distinct Kaiser effect was observed in the acoustic emission signals. However, under severe damage conditions induced by high static stress and strong disturbance, this effect transitions rapidly to a Felicity effect, indicating a degradation in the rock’s stress memory capability.
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Mine Restoration in the Nanling Ethnic Corridor to Facilitate the Realization of Ecological Product Value：Advancement Mechanisms and Optimizing Pathways
Abstract:
Against the backdrop of the national dual-carbon strategy and the advancement of the ecological product value realization mechanism, this study addresses the disconnect between mine restoration and ecological product value conversion within the Nanling Ethnic Corridor. Employing grounded theory to conduct systematic coding analysis, it examines 20 multi-ore mine restoration cases in the region. The research first identifies four critical issues: inefficient utilization of waste resources, prominent technical bottlenecks, weak funding sustainability, and ineffective cross-departmental coordination. Subsequently, integrating the region"s core attributes of multi-mineral complexity, cross-domain governance, and ethnic interdependence, it constructs a four-dimensional optimization pathway: revitalizing industries through waste recycling, overcoming technical barriers, innovating funding mechanisms, and strengthening systemic governance. Results demonstrate that this pathway can specifically address region-specific rehabilitation challenges, supplementing theoretical gaps in realizing the value of ecological products from mine rehabilitation within the ethnic corridor. It provides a replicable ‘Nanling experience’ for transforming ‘lucid waters and lush mountains’ into ‘mountains of gold and silver’ across multi-ethnic regions, while also offering methodological references for similar ecological product value realization studies in comparable areas.
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Phosphorus and Fluorine Impurities Regulate the Mechanical Strength and Microstructure Evolution of Phosphogypsum Cemented Backfill
Abstract:
To reveal the influence of phosphorus and fluorine impurities on the performance of phosphogypsum cemented backfill, four impurities of NaF, Na2SiF6, H3PO4 and Ca3(PO4)2 were selected as the research objects, and the changes of setting time, slump, bleeding rate, compressive strength, softening coefficient and hydration mechanism were discussed. The results show that the fluorine impurity can significantly shorten the setting time, while the phosphorus impurity shows a retarding characteristic. With the increase of fluorine impurity content, the slump and bleeding rate of the slurry show a gradual decreasing trend, while with the increase of phosphorus impurity content, the slump and bleeding rate do not fluctuate significantly. The incorporation of NaF makes the compressive strength increase first and then decrease. Na2SiF6 also reveals similar nonlinear changes. When the content is 0.45%, the compressive strength of each age reaches the optimal value. This is because an appropriate amount of fluorine impurities can effectively promote the hydration reaction and accelerate the formation of hydration products. However, the hydration system containing phosphorus impurities showed that the compressive strength continued to decrease with the increase of the content. The microscopic analysis showed that the impurities did not introduce new phases, but significantly affected their relative content and microstructure. An appropriate amount of fluorine impurities promoted the formation of ettringite and C-(A)-S-H gel, which were overlapped into a dense structure to optimize the pore distribution and enhance the mechanical properties. Noneless, phosphorus impurities hinder the hydration process of slag and steel slag, resulting in the decrease of hydration products, the weakening of crystal bonding, the increase of porosity and the expansion of micro cracks, which eventually lead to the significant deterioration of macro strength.
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Research and application of long span stope support technology for unstable ore body
Abstract:
To solve the technical problems of roof support in the large-span stope under the condition of unstable ore bodies in the second mining area of the ?ukaru-Peki copper-gold mine, an innovative double-arch large-span roof joint support technology was proposed. This support technology is aimed at strengthening the high-risk area in the middle of the double rock drilling tunnels at the top of the stope. It combines the combined support of prestressed anchor cables and resin anchor rods to construct a composite support structure of “prestressed anchor cables + resin anchor rods + metal mesh + shotcrete” with gradient energy dissipation characteristics. A three-dimensional numerical model of a typical stope was constructed using the FLAC3D platform, and the stability of the stope under the adoption of this new combined support scheme was analyzed. The numerical simulation results show that the new combined support scheme has a significant effect in controlling the deformation of the roof, reducing the maximum settlement of the roof by 33%. After the implementation of the combined support technology on site, it was found through monitoring that the load monitoring values of the anchor cables at both ends of the stope were stable at about 72% of the design value, approximately 187.2kN. There were no cases of stress over-limit failure. The roof of the stope remained stable for one week after mining, significantly enhancing the stability and safety of the roof. The research has broken through the traditional support concept of “passive bearing”, forming a technical path of “active support - coordinated bearing - dynamic stability” for unstable roof slabs. This achievement provides a reference for the design of roof support in metal mine stopes under similar geological conditions.
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Research on The Coupling and Coordination of Industrial Resilience and Technological Innovation of Mining Enterprises——Based on the Panel Data of 24 Listed Mining Enterprises
Abstract:
[Objective] Industrial resilience and technological innovation are the key factors to promote the development of enterprises. The coupling and coordinated development between the two is very important to improve the overall performance and competitiveness of enterprises and industries, and is conducive to breaking through the bottleneck of enterprise development. [Methods] In order to understand the development degree of scientific and technological innovation and industrial resilience of listed companies in mining enterprises, 24 listed companies of science and technology mining enterprises were selected as the research objects. Through the panel data from 2017 to 2024, the evaluation index system of scientific and technological innovation and industrial resilience was constructed, and the entropy method and coupling coordination degree model were used for empirical calculation. [Results] ① The relationship between industrial resilience and scientific and technological innovation of listed companies in mining enterprises is mostly lagging behind in scientific and technological innovation. During the study period, the comprehensive development level of industrial resilience showed a slow upward trend, and the comprehensive development level of scientific and technological innovation only had a small increase after the fluctuation. ②There is a complex relationship between scientific and technological innovation and industrial resilience, but most enterprises are in a stage of serious coupling imbalance. Although they also show an upward trend during the research period, it is urgent to overcome the existing constraints to achieve further development. [Conclusion] Enterprises should establish a dynamic monitoring and early warning mechanism, attach importance to the investment in intelligent mining, and carry out green intelligent transformation with the support of precise financial tools, so that industrial resilience and technological innovation can develop in a long-term and balanced manner.
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Research?on?the?Height?Optimization?of?Deep?Backfill?Mining?in?Large-scale??Mo-Pb-Zn?Polymetallic?Mines
Abstract:
Some mines in China have faced serious threats to the safety of surface buildings and resource waste due to improper handling of underground voids. In response to the special challenges of deep mining (750-1000 m) in the Chaoliu Road molybdenum-lead-zinc polymetallic mine in the Greater Khingan Range under complex geological structures and volcanic rock conditions, a study on the optimization of the height of the filling stage based on rock mechanics and numerical simulation was carried out. Firstly, the mechanical parameters of the main rock masses in the mining area were obtained through rock mechanics tests, and a three-dimensional geomechanical model accurately reflecting the geological structure and topography of the mining area was constructed by comprehensively using 3Dmine, ANSYS and Surfer software. Then, using the FLAC3D numerical simulation, the effects of three filling stage heights of 60 m, 90 m and 120 m on the stability of the stope and surface were systematically compared and analyzed. The research results show that a stage height of 60 m can effectively inhibit the expansion of the plastic zone, control displacement and stress concentration, and is the optimal solution for safety and economy; a height of 90 m can basically maintain stability, but there is a risk of local plastic zone connection; while a height of 120 m far exceeds the safety limit. The research results have clarified the safety threshold for mining height of this complex deep ore body and revealed the internal mechanism of plastic zone connection caused by the increase in stage height. It not only provides direct design basis for the safe and efficient mining of the Chaoliu Road mine, but also offers important theoretical reference and practical cases for the optimization of deep filling mining schemes under similar complex geological conditions.
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Research on the Propagation Law of Gas Explosion in the Upper Corner of Coal Mine Fully Mechanized Mining Face
Abstract:
The fully mechanized mining face is the core area of coal mine production. Due to low wind speed at the edge of the goaf and obstructions from hydraulic supports, the upper corner of the return air pathway is prone to gas accumulation, increasing the risk of gas explosions. To prevent and mitigate the damage caused by gas explosions, a systematic numerical simulation was conducted to analyze the coupling relationships among overpressure, flame, temperature, and airflow velocity during the propagation of explosion shockwaves through roadway networks. Furthermore, the possibility of secondary explosions in the presence of coal dust was investigated. The results indicate that when the length of the return airway significantly exceeds that of the working face, the bidirectional movement and coupling of flames generated by a gas explosion in the upper corner cause a reciprocating flame propagation phenomenon along the working face. This leads to excessive oxygen consumption and high temperatures, posing multiple hazards to personnel. Near locations such as bends and bifurcations, the reverse conversion of airflow kinetic energy to pressure energy is a key factor causing the rise in overpressure. When a coal dust layer is laid in the middle section of the working face, the maximum flame propagation distance along the working face is 57m during shockwave propagation. The coal dust cloud undergoes reciprocating motion within a range of 110–160 m from the upper corner, while the flame and high temperatures do not reach the coal dust cloud area, thus avoiding secondary explosion hazards. The research findings provide theoretical and technical support for field engineers to enhance underground safety protection and develop technologies for reducing damage from gas explosions.
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Study on Key Influencing Factors and Scheme Optimization Selection for Hydraulic Mineral Collection in Deep-Sea Environment
Abstract:
To ensure efficient resource extraction while minimizing environmental impacts and improving economic feasibility, a hybrid evaluation system was constructed to identify key influencing factors and optimize schemes for the sustainable development of deep-sea hydraulic mineral collection technology. First, based on grounded theory, twenty influencing indicators were identified from the technological, environmental, and economic dimensions. Then, using game theory, the subjective and objective weights obtained through the Fuzzy-DEMATEL method and the CRITIC method were integrated to determine comprehensive weights. Finally, the Pythagorean Fuzzy Hybrid Weighted Distance-TOPSIS (PFHWD-TOPSIS) method was applied for multi-attribute decision-making to rank and optimize the alternative schemes. The results show that the proposed hybrid evaluation system can scientifically and effectively perform factor analysis and scheme optimization. Environmental disturbance, collection efficiency, energy consumption characteristics, structural reliability, and economic feasibility of collection are identified as the key dimensions influencing deep-sea hydraulic mineral collection scheme selection. The findings provide theoretical support for the optimization of deep-sea hydraulic mineral collection schemes and contribute to the sustainable development of deep-sea hydraulic mineral collection technology.
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Experimental Research and Application on Quality Improvement and Gangue Reduction of Zinc Sulfide Concentrate
Abstract:
Yunnan Dolong Mining Area's Zinc-Lead Ore Processing Plant Faces Severe Issues with High Silica Gangue Content in Zinc Concentrate, Severely Impeding Smelting Efficiency and Economic Benefits Mineralogy diagnosis revealed that the root cause of this issue lies in the similar particle size distribution and minimal floatability differences between silicate gangue minerals and target minerals, resulting in inefficient conventional separation methods. To address this challenge, a quality-improvement and silica-reduction experimental study was conducted. Research found that sodium hexametaphosphate demonstrated exceptional selective inhibition and dispersion capabilities for such silicate gangue. Through conditioning tests, the optimal process scheme was determined: blending zinc mixed selective concentrate with zinc rougher-cleaner concentrate at a 2:1 ratio, under grinding fineness of -0.038 mm (80.38%), flotation concentration of 23%, and a high-alkali (pH=11-13) sulfur-suppression flotation process with staged sodium hexametaphosphate addition (60 g/t for roughing, 10 g/t for first cleaning). Closed-circuit testing yielded high-quality zinc concentrate (Zn grade 46.23%, recovery 99.12%, SiO2 content 3.80%). Industrial trials successfully validated the technology's reliability and stability, while observing that sodium hexametaphosphate significantly improved flotation foam fluidity, ensuring smooth production. This provided Dolong Mining Area with a directly applicable, high-efficiency solution. The research approach of "customized reagent systems based on ore properties" and its successful implementation also offer valuable insights for processing similar complex and refractory zinc ore resources.
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Mechanism and prevention technology of water gushing from the roof of deep well due to mining-induced subsidence
Abstract:
To address the problem of sudden and destructive water disasters caused by mining-induced displacement of strata in deep area,this paper takes the 1605 working face of GuHanshan Mine as the engineering background. Using field observation, theoretical analysis and numerical simulation as research methods,the location of the displacement layer in the overlying strata during mining was determined,the spatial and temporal distribution and evolution mechanism of the displacement layer during the working face"s mining process were clarified,and the quantitative relationship between the vertical development height (H) of the displacement layer,the advancing distance of the working face (L),and the fracture characteristics of the rock strata was proposed. The results show that the core water accumulation displacement layer is located at the junction of the Shanxi Formation and the Xiaoshibuzi Formation,constituting the source of water inrush disasters；during the working face"s mining process,a stable water storage period occurs within 130-180 meters from the cutting hole,and then the vertical mining-induced fractures develop upward and connect the displacement layer space；the vertical development height of the displacement layer is approximately 0.4 to 0.7 times the advancing distance of the working face, the side fracture angle of the working face varies between 65° and 78° due to the influence of mining,while the side fracture angle of the cutting hole remains relatively stable at 75°；it is determined that the working face reaches the position near the initial and periodic roof fall pressure stage as the high water inrush risk area. On-site,a one-hole two-stage casing structure is adopted to achieve the upper sealing and lower drainage of the displacement layer water,which is of great significance for ensuring the safe mining of Gu Hanshan Mine,protecting underground water resources and promoting green mining.
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Experimental Study on Flotation Purification of Quartz Sandstone in Hebei Province
WANG Shuo, 聂轶苗, 杜孟泽, 陈洁, 刘淑贤, 王玲
Abstract:
Addressing the contradiction between the substantial reserves yet low grade of quartz sandstone resources and the industrial demand for high-purity quartz, systematic investigation was conducted on the technical feasibility of producing high-purity quartz sand via flotation purification. The raw quartz sandstone from Hebei Province, with an initial SiO? content of 98.07%, was pretreated through a "crushing- grinding- screening-magnetic separation" process, yielding a quartz sand feedstock (particle size: 0.106–0.212 mm) assaying 99.04% SiO? and 0.490% Al?O?. A comparative assessment of alkaline direct flotation and neutral reverse flotation was carried out, examining the performance of dodecylamine and sodium oleate as collectors, and sodium fluorosilicate as a depressant, under varied conditions. Experimental results demonstrated that in alkaline direct flotation, collector addition enhanced quartz hydrophobicity, producing a concentrate with 0.237% Al?O? at a recovery of 97.55%. In neutral reverse flotation, the selective depression of quartz by sodium fluorosilicate proved critical for effective quartz-gangue separation, yielding a concentrate with 0.210% Al?O? and 89.19% recovery. To synergistically optimize purification efficiency, a hybrid "neutral reverse rough flotation-alkaline direct cleaning flotation" flowsheet was developed. This integrated process ultimately produced a quartz sand concentrate assaying 99.67% SiO? and 0.190% Al?O?, with a recovery rate of 83.46%. The proposed hybrid process effectively purifies quartz sandstone, providing a technical framework for the high-value utilization of comparable resources.
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Visual prediction of plastic zone of surrounding rock in three-center arch roadway based on machine learning
Abstract:
The plastic zone of surrounding rock of roadway is the key basis to guide the support design. Aiming at the limitation of traditional mechanical analysis method for solving the plastic zone of surrounding rock of three-center arch roadway, a visual prediction algorithm model of plastic zone based on machine learning is proposed. Nine influencing factors were selected to design numerical simulation orthogonal experiments, and the importance of each factor to Z value (the ratio of roadway section to plastic zone area) and K value (the distance ratio of roadway center point to plastic zone boundary to section boundary) was quantified by Pearson correlation. Seven key parameters were determined as model inputs. The sample data set was constructed by FLAC3D wide parameter range modeling method, and the K value output at 36 angles was realized by improving BP neural network and random forest. The 36 plastic zone boundary points were determined to fit the plastic zone range. The results show that the maximum relative error between the output of the improved model and the numerical simulation results is 4.77 %, which can well complete the prediction task of the plastic zone of the surrounding rock of the three-center arched roadway under a single lithology. The visual plastic zone is consistent with the distribution of the failure characteristics of the surrounding rock loose circle of the-410 m roadway in Jinshandian Iron Mine. The maximum failure depth is shown in the two sides and shoulders of the roadway. The average depth of the measured loose circle is 1.77 m, and the average depth of the predicted plastic zone is 2.41 m, which can provide a reference for the design of bolt support.
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Study on Evolution Characteristics of Pillar Failure Instability and Application of Monitoring and Warning
Abstract:
Acoustic emission test of pillar failure, PFC simulation of pillar failure and stability monitoring and early warning research were carried out to solve the problem of pillar stability. The evolution characteristics of stress and acoustic emission during pillar failure were analyzed. Four incubation periods of pillar failure were proposed: initial incubation period, low incubation period, accelerated incubation period and pillar failure period. Based on the evolution characteristics of pillar failure stress-acoustic emission, five discriminant modes of pillar failure were proposed, which are pressure increase-AE stabilization mode, pressure stabilization-AE stabilization mode, pressure drop-AE stabilization mode, pressure increase-AE increase mode，pressure drop- AE increase mode. Based on the instability criterion of pillar failure, a phased early warning method of pillar stability was established, and a comprehensive monitoring and warning platform for pillar stability was developed. Pillar instability criterion and phased early warning method have good results in field engineering application. After 2-45# pillar enters the stage of pressure increase-AE increase, longitudinal cracks appear 39 days after the red warning, overall damage occurs 90 days after the red warning, and after 2-105# pillar enters the stage of pressure increase-AE stabilization, local spalling occurs 38 days after the yellow warning. The research results are of great significance for the quantitative evaluation of pillar stability and the guarantee of mine safety production.
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Modeling and analysis of key influencing factors on safety clearance in mixed lifting of ultra-deep wells
Abstract:
To analyze the influence of external flow field pressure changes on safety clearance during the operation of ultra deep well metal mine lifting vessels, and effectively obtain the key factors for the design of safety clearance of ultra deep well mixed lifting volume, a closed-loop analysis method combining multi field coupling dynamics, specification clauses, and engineering design is proposed to study the key indicators of safety clearance under different working conditions of ultra deep well mixed lifting. Firstly, based on Guizhou daping phosphate metal mining project under construction, a standard kappa - ε two equation turbulence model was used to conduct precise numerical analysis of the pressure changes in the external flow field during the operation of the lifting container. The pressure changes of the container during steady-state operation and transient processes were deeply explored. At the same time, other key factors affecting the oscillation of the container, such as the twisting torque of the lifting wire rope, Coriolis force, and steady-state aerodynamic force, were comprehensively considered. Through systematic research and analysis, the ultimate design safety clearance of the ultra deep well lifting container was determined, providing a scientific and reliable basis for the safety design of the ultra deep well wellbore, and ensuring the stable and safe operation of the lifting system in deep mining. The research conclusion provides a quantitative basis for the aerodynamic effects of deep wells and a dynamic clearance calculation methodology for the subsequent revision of GB 16423-2020, and provides research ideas for the analysis of new safety margin evaluation standards for the design of ultra deep well safety clearances.
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Research on safe and efficient mining methods for thick and large ore bodies in high-altitude electric quartz rock formations
Abstract:
In response to the complex and variable boundaries, low ore recovery rate, large exposed area of the roof, and low degree of mechanization of thick and large ore bodies in high-altitude electric quartz rock type, in order to achieve the goal of safe, efficient, and green mining, the occurrence characteristics of thick and large ore bodies in electric quartz rock were systematically analyzed, and four technical solutions were proposed. The advantages and disadvantages, main technical and economic indicators, and comprehensive benefits of each solution were compared, and the upward tunneling filling method was finally determined as the optimal mining solution; Based on the Mathews stability diagram method, the maximum allowable exposed area of the ore body and surrounding rock was obtained. Combined with numerical simulation, the distribution patterns of stress, vertical displacement, and plastic zone under different access sizes were revealed, and the optimal access parameters were determined to be 5.0m × 3.5m; On site industrial tests showed that the maximum subsidence of the roof in the mining area was 19.2mm, and there was no collapse phenomenon; The ore loss rate is 3.2% and the impoverishment rate is 3.5%, which is 8.8 and 8.5 percentage points higher than the shallow hole retention method, and the effect is significant. The research results provide a technological paradigm for similar mines and promote the sustainable development of high-altitude mineral resources.
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Research and Application of Low-Carbon Solid Waste Cemented Gold Tailings for Mine BackfillingZHANG Yi heng1,2,SUN Xigang3 ,PAN Feng 1,2, JIANG Hongjian3,ZHANG Sukun1,2
Abstract:
This study focuses on the backfilling of graded tailings from the Shishudi Gold Mine. The physical and chemical properties of the graded tailings and industrial solid wastes were analyzed. A low-carbon solid waste cementitious material was prepared using slag powder, steel slag powder, and F-gypsum as the main raw materials, with sodium hydroxide, sodium silicate, and aluminum sulfate as composite activators. Through a mixture design model in response surface methodology, the influence of different mass ratios of each component on compressive strength was analyzed. The reliability of the model was verified, and the optimal mix ratio for the low-carbon solid waste cementitious material was determined as follows: slag : steel slag : F-gypsum : activator = 70.69 : 10.52 : 18.79 : 5. The reliability of the experimental results was confirmed. XRD, SEM-EDS, and hydration heat analysis were used to study the phase composition, microscopic morphology, and hydration kinetics of the low-carbon solid waste cementitious material. The main hydration products were C-S-H gel, ettringite, and calcite. The hydration heat release rate and total heat release were reduced by more than 30% compared to cement. Comparative tests and pilot-scale experiments demonstrated that, under the same technical indicators, using low-carbon solid waste cementitious material to replace cement for gold tailings backfilling can reduce the consumption of cementitious materials by more than 50%, increase tailings utilization by over 10%, lower costs by over 30%, and reduce carbon emissions by 90% compared to cement-based tailings backfilling. This approach exhibits significant economic and social benefits.
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3. Guangxi China Tin Group Co., Ltd., Liuzhou 545006,Guangxi,China4. School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Abstract:
As biodiversity conservation becomes an increasingly prominent global concern and a central element of sustainable development, integrating biodiversity protection into mining activities is essential for fulfilling corporate social responsibility and enhancing overall competitiveness. China’s biodiversity conservation efforts in the mining sector are currently undergoing a transition from being primarily policy-driven to increasingly characterized by technological integration and systematic practice, with an urgent need for further refinement and enhancement of methodological frameworks and implementation pathways. Grounded in the internationally accepted Mitigation Hierarchy Framework, key biodiversity conservation actions are identified across different phases of the mining life cycle: (1) In the planning phase, comprehensive baseline biodiversity assessments and socio-economic impact evaluations are conducted to inform tailored biodiversity management plans; (2) During the operational phase, effective implementation of management plans is ensured through continuous ecological monitoring and adaptive management; (3) In the transition from operation to closure, systematic restoration and rehabilitation efforts aim to rebuild stable, self-regulating local ecosystems; (4) At closure, the focus shifts to long-term ecosystem functionality and sustainable land use, supported by closed-loop management and ecological compensation mechanisms to align environmental conservation with regional development. This study takes the Ambatovy mine in Madagascar as a representative case to examine biodiversity conservation practices under the framework of the mitigation hierarchy. By analyzing its approaches and outcomes, the study aims to provide insights for the development of biodiversity-friendly mines across the full life cycle in China, thereby supporting mining enterprises in achieving high-quality and green development.
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Experimental StudyExperimental study on nano-TiO2 modified coal-based solid waste grouting material based on loose layer
Abstract:
The loose layer generally has the characteristics of loose structure, high porosity,strong permeability and poor cementation between particles.In the process of coal mining,it is often necessary to carry out grouting reinforcement treatment.In order to improve the utilization rate of coal-based solid waste and effectively solve the problem of grouting materials in the formation,this study uses coal-based solid waste resources (coal gangue, fly ash and slag) to develop a geopolymer grouting material based on coal-based solid waste.By optimizing the key parameters such as fluidity and compressive strength of the slurry,it is adapted to the engineering characteristics of the loose layer.In order to compensate for the loss of specific strength caused by the incorporation of coal gangue, nano-TiO2 (2.3%),cationic polyacrylamide (0.44%) and polycarboxylate superplasticizer (1.6%)were added.Through Design-Expert software regression analysis and response surface,the response values of different variable combinations can be effectively predicted,and the admixtures can be quantitatively optimized.The physical performance test of the slurry,the strength test of the stone body and the SEM microstructure characterization were carried out to verify the material properties.Finally,the optimum ratio is determined as follows:fly ash:calcined coal gangue is 6:4,slag accounts for 30%.Through indoor simulation experiments,compared with traditional cement grouting materials,the applicability and performance advantages of coal-based grouting materials are verified, which provides a scalable technical solution for grouting projects under similar geological conditions.
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Optimization of structural parameters of Linglong gold mine based on FLAC3D
Abstract:
Abstract: With shallow mineral resources becoming increasingly depleted, deep mining has become an inevitable choice to ensure resource supply, making the safety of deep mining areas a top priority. Current research in this field predominantly employs rock mass classification and stability chart methods for evaluating mining area stability and optimizing parameters. While significant progress has been made in integrating and applying theoretical methods, challenges remain in accurately obtaining rock mass parameters and precisely characterizing joint networks. Therefore, this study takes the deep mining of Linglong Gold Mine as its engineering context, aiming to determine the safe and economical span of mining access tunnels. Through on-site rock mechanics tests, structural surface photogrammetry, and four rock mass classification methods, the rock mass quality is comprehensively evaluated. Subsequently, preliminary analysis is conducted by integrating the RMR and Mathews stability chart methods, and a FLAC3D numerical model is established to simulate and analyze the stability of mining areas under different tunnel spans and surrounding rock grades. Results indicate: Although uniaxial compressive strength reaches 113.4 MPa, highly developed joints result in overall Grade III rock mass quality (locally Grade IV). Beyond 6m spans, Grade III roof displacement and plastic zone extent increase sharply; Grade IV rock mass exhibits displacement up to 47.10mm with significantly poorer stability. Based on these findings, the optimal roadway span for Grade III rock mass is determined to be 5–6 m, while Grade IV rock mass should be limited to 4 m with reinforced support. This study provides methodological guidance and design basis for optimizing parameters in similar deep mine workings.
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Research on the Mechanical Behavior and Acoustic Emission Characteristics of Granite Based on Three-point Bending Test
Abstract:
To clarify the mechanisms of tensile fracture and collapse in granite roof strata during deep mining, three-point bending tests were conducted on fine-grained Luotian, coarse-grained Huangjinma, and medium-grained Yunfu granite samples. Acoustic emission (AE) monitoring was employed to systematically investigate the bending strength, dominant frequency distribution, damage evolution, and crack propagation patterns. The results indicate that bending strength exhibits a significant grain-size effect. The fine-grained Luotian granite showed the highest strength (17.79 MPa), with brittle fracture characterized by a sharp post-peak stress drop. The coarse-grained Huangjinma granite had the lowest strength (5.33 MPa), displaying clear ductile characteristics. The medium-grained Yunfu granite fell between the two (16.04 MPa), demonstrating a brittle-ductile transition after the peak. AE signals were concentrated near the peak load and in the post-peak stage, forming three main frequency bands: 0–40 kHz, 50–80 kHz, and 130–180 kHz. The Luotian granite exhibited a pre-peak surge in high-frequency signals (130–180 kHz), while the Huangjinma and Yunfu granites showed dominant frequencies mainly in the low-frequency band (0–40 kHz) during the post-peak stage. Damage evolution consistently followed three stages—initial damage, stable development, and accelerated development—with damage accumulation highly concentrated in the post-peak stage. The Huangjinma granite had the highest damage proportion, while the Luotian granite released the most energy per unit damage. RA-AF analysis revealed that failure was predominantly governed by tensile cracks, with the proportion of tensile cracks negatively correlated with grain size. The Luotian granite had the highest proportion of tensile cracks, exceeding that of the Yunfu and Huangjinma granites by 3.17% and 6.15%, respectively. A quantitative early warning method for roof instability based on dominant AE frequency signals is proposed, providing theoretical and practical guidance for stability assessment and dynamic disaster prevention in deep mining.
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Direct Simulation Method of Seepage Well Drainage Unit in Seepage Analysis of Tailings Pond
Abstract:
On the basis of summarizing the simulation method of drainage hole unit in the finite element calculation of seepage field, the direct simulation method of drainage unit of seepage well in tailings pond is put forward. The method is to establish a solid grid model containing the optimization parameters of the seepage well at the beginning of the calculation, and then group the optimization units of the seepage well in advance by setting different internal boundary conditions. In the finite element calculation of seepage field, only one seepage conduction matrix condensation work can be carried out. In the calculation process, the information of each group node is processed according to the first kind of known head boundary conditions. The whole process is easy to program and the solution speed is fast. Compared with the implicit composite element method or the improved drainage substructure method commonly used in engineering, this method greatly improves the modeling and solving efficiency through parameter optimization settings, and greatly improves the calculation accuracy through fine simulation of the size effect of seepage wells. Finally, the calculation accuracy of the method is verified to meet the engineering requirements through the complete well example and the specific engineering example.
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Analysis of Spatiotemporal Differentiation and Convergence of Market-based Allocation Level of Mineral Resources in China
Abstract:
To implement the reforms of promoting factors market-based allocation and improving the mining rights transfer system, and to understand the trends in market-based allocation of mineral resources in China, a study was conducted on the level, spatiotemporal evolution and convergence of market-based allocation of mineral resources from 2003 to 2023. Methods such as transaction count proportion, kernel density estimation, the Dagum Gini coefficient, and σ and β convergence models were employed.The results showed that the market-based allocation level of mineral resources in China increases from a low marketization level of 40.48%, to a moderate level of 76.23%. The role of the market in allocating mineral resources continues to strengthen.The eastern region reach a relatively high marketization level of 82.26%, while other regions remain at a moderate level. The market-based allocation level of operation rights is higher than exploration rights.Non-metal minerals and water-gas minerals are higher than energy minerals and metal minerals.The primary market surpass the secondary market in recent year.The overall national disparity narrows gradually.The average contribution rates of inter-regional interactive effects, inter-regional disparities, and intra-regional disparities are 43.88%, 29.49%, and 26.68%, respectively. Intra-regional disparities remain prominent in the eastern and northeastern regions, while significant inter-regional disparities exist between the northeast-eastern regions, northeast-central regions, and northeast -western regions. The market-based allocation levels across the nation and four major regions exhibit both σ convergence and β convergence, though the convergence rates vary. Lower-marketization regions demonstrate a catch-up effect relative to higher-marketization regions. Economic development levels, industrial structure, urbanization, fiscal conditions, mineral mining rights endowment, and resource dependency exert heterogeneous effects on changes of market-based allocation levels. Considering these factors, the market-based allocation levels across regions converge to their respective steady-state levels. The findings provide important references for further optimizing market-based reform policies and promoting high-quality development in the mining industry.
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Similar model test research and engineering application of contractible concrete-filled steel tube support
Abstract:
Aiming at the problem of large deformation control of surrounding rock in deep high ground stress roadway, a contractible concrete-filled steel tube support structure ( referred to as " contractible support " ) is proposed.Firstly, the comparison test of contractible similar structure was carried out, and pvc foam was determined as the contractible similar material of model test. Based on this, the similar model test of the retractable support was carried out, and obtains the stress-time and load-displacement curves of the whole process of static load. The changes of the contractible support and the generation and expansion of concrete cracks were monitored, and reveals the three-stage mechanical response of the contractible support : elastic deformation stage, stable pressure-relief stage and rigid stage after pressure-relief. The test results show that the peak stress of the surrounding rock of the roof and floor is about 0.7 MPa, the peak stress of the surrounding rock of the left and right sides is about 1.4 MPa, and the stress of the surrounding rock is transferred to the deep. There is no instability deformation in the whole supporting model, and the support is bent but still maintains the structural integrity. Test results show a contraction rate of approximately 77% for the pvc foam., and the support demonstrates good pressure-relief performance. Field support results show that the maximum displacement of the roof and floor of the surrounding rock reaches 216 mm, the contraction rate of the contractible support is approximately 72%. The contractible support demonstrates effective pressure-relief performance. The support structure effectively coordinates the collaborative deformation between the surrounding rock and the support, providing valuable reference for both research and engineering application of contractible support systems.
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Optimization of mining scheme and analysis of wellbore stability in near wellbore mining area of steeply inclined thin orebody
Abstract:
Scientific and reasonable design and implementation of mining scheme is the key to ensure the stability of surrounding rock structure of mine shaft. Aiming at the newly-added and recoverable near-wellbore area of steeply inclined thin ore body, combined with the geological conditions of the mine, the applicable mining method is preliminarily selected, and the primary selection scheme is optimized by using analytic hierarchy process and fuzzy decision theory. Through FLAC3 D numerical simulation, the wellbore stability in the mining process of the newly recoverable near wellbore area is analyzed. The research results show that combined with the analytic hierarchy process and fuzzy decision theory, the upward drift filling method is determined to be the optimal mining scheme for the new delineation area of the shaft security pillar. Compared with the upward mining, the downward mining effectively reduces the maximum unbalanced force, reduces the local stress concentration of the ore body, and helps to suppress the ground pressure activity and control the displacement of the shaft. The optimized stoping sequence significantly improves the safety factor by gradually releasing the stress. In addition, the stability of the filling body plays a key role in the supporting role in the mining process and avoids the destructive expansion of the rock mass. The monitoring results of the shaft show that on the basis of the downward mining scheme, the compression and tensile deformation of the shaft meet the requirements of the safety regulations.
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Research on Multi-body Coupled Dynamics Analysis and Safety Design of an Inclined Shaft Hoisting Container
Abstract:
In inclined shaft hoisting systems, the conveyance carries substantial loads and operates at high speeds. When a runaway vehicle brakes, it generates immense impact forces. Existing runaway vehicle protection devices primarily rely on passive safety mechanisms installed within the shaft for interception, lacking the ability to adapt to dynamic changes in impact energy or to effectively reduce and absorb that energy. Consequently, this paper proposes a design and optimization method for an inclined shaft conveyance with adaptive multi-stage buffering to achieve mechanical braking and segmented absorption of impact energy following a runaway event. A multi-body coupled impact dynamics model of the multi-stage buffering conveyance on an inclined track was established based on its structure to study the influence of multi-stage buffering on the braking impact force of the hoisting system. The stiffness of the buffer springs was optimized using the Sequential Quadratic Programming (SQP) algorithm. The results show that the multi-stage buffering structure reduces the impact force by 24.5% compared to a system without buffering. After optimization, the spring stiffness further reduces the impact force by 35.5%. This demonstrates that the multi-stage buffering structure can effectively suppress the braking impact force, and the SQP algorithm can successfully optimize the buffer spring stiffness, thereby enhancing impact energy absorption efficiency, improving the system's impact resistance, and preventing secondary impact oscillations. This research provides a theoretical foundation for the anti-impact design of hoisting conveyances and the development of safety braking strategies.
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Study on Mechanical Properties and Energy Evolution Laws of Fractured Sandstone in Natural and Saturated States
Abstract:
In order to reveal the mechanical properties and energy evolution laws of fissured sandstone under water-bearing conditions, sandstone from a mine in Ordos was selected as the research object. Uniaxial compression tests were carried out on sandstone specimens under two states (natural and water-saturated) and different fissure dip angles (0°, 30°, 60°, 90°) using the microcomputer-controlled rigid impact test system for coal and rock (TDW-600). The full stress-strain curves and physical-mechanical parameters of sandstone specimens under uniaxial compression were obtained. The energy evolution laws of sandstone specimens during the entire uniaxial compression loading process were explored, and the effects of natural and water-saturated states on crack propagation of specimens with different fissure dip angles were analyzed. The results show that compared with intact sandstone, the peak strength and elastic modulus of sandstone specimens with fissure dip angles decrease significantly. The total energy absorbed by sandstone specimens in the natural state is approximately 1.85 times that in the water-saturated state, and the total energy increases with the increase of fissure dip angle. The proportion of elastic strain energy reaches more than 92% in the stable damage stage and drops to less than 61.5% in the accelerated damage stage, while the proportion of dissipated energy shows the opposite trend. The failure mode exhibits significant anisotropy. The deterioration effect of water reduces the crack initiation stress by 13.4%–18.2% and increases the spalling phenomenon of rock blocks. Fissure dip angle and water-bearing state have a crucial impact on the mechanical properties, energy evolution, and failure mode of sandstone. The research results can provide a theoretical basis for the stability control of water-rich fissured rock mass engineering.
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Water Inrush Control Technology Using Curtain Grouting and Effectiveness Evaluation in a Metal Mine
Abstract:
[Objective] Precision curtain cutoff technologies and multi-dimensional evaluation methods are urgently required to address complex karst water hazards in deep metal mining. A comprehensive framework for rapid water hazard control assessment is established.[Methods] Karst channels were pre-identified at the ZK iron mine through integrated geophysical and drilling techniques. Precision grouting was implemented with dynamically adjusted parameters (pressure: 2–4 MPa; water-cement ratio: 1:1–0.6:1). Groundwater flow field variations before and after curtain cutoff were simulated using FEFLOW software. A multi-dimensional evaluation system incorporated grout volume analysis, hydrogeological monitoring, geophysical surveys, inspection hole verification, and AHP quantitative assessment.[Results] Precision grouting effectively sealed complex karst-fissure networks, reducing daily drainage from 22,984 m3/d to 7,984 m3/d (water-blocking efficiency: 65%). FEFLOW simulations predicted 15,214 m3/d inflow reduction (efficiency: 66.2%), aligning with field measurements. The AHP evaluation scored 0.895 (excellent grade), with drainage reduction rate (weight: 31.1%) contributing most significantly to the outcome.
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Experimental Study on Deep Reduction and Iron-Titanium Separation of Titanium-Bearing Hematite Rough Concentrate Based on Thermodynamic Analysis
Abstract:
A rutile ore in Hebei Province is associated with hematite. The rutile particles are fine and intergrown with or enclosed by hematite, making it difficult to achieve sufficient dissociation. The separation effect of magnetic separation is poor, and it is challenging to separate titanium and iron.Reduction roasting has been proven as an effective technological approach for achieving efficient liberation of fine-grained iron ores from associated gangue minerals.In this study, a process of deep reduction followed by magnetic separation was employed to treat a titanium-bearing hematite coarse concentrate, resulting in a relatively satisfactory separation performance between iron and titanium.The mineralogical composition and elemental distribution were systematically characterized using an automated mineralogy analysis system and scanning electron microscopy (SEM). Thermodynamic calculations and simulation were conducted to investigate the reaction pathways of iron-bearing and gangue minerals during the reduction process, thereby assisting in determining the optimal experimental conditions: a reduction temperature of 1623 K, a reduction time of 120 minutes, a carbon-to-oxygen (C/O) molar ratio of 2.0, and a magnetic field intensity of 85 mT.The metallization rate of the reduction product reached 78.94%. The total iron grade and total iron recovery rate of the iron concentrate were 89.08% and 88.39% respectively. The TiO? grade and TiO? recovery rate of the titanium concentrate were 36.67% and 71.88% respectively, indicating ideal beneficiation indicators.
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Analysis of deep mining-induced effects on roadway surrounding rock stability and drift scheme optimizationYIN Anran1,PENG Chao1,HU Shang1,JIA Hanwen2,LIU Guodong3
Abstract:
This paper addresses the scientific and engineering issues related to the impact of deep-level mining disturbances on the stability of tunnel surrounding rock. Taking the Sanshandao Gold Mine as the engineering background, the study combines FLAC3D numerical simulation with field monitoring data to compare and analyze the evolution patterns of surrounding rock failure in segmented flat tunnels and main cross-tunnels in the mining area under different mining parameters and mining sequences. Based on the characteristics of tunnel displacement and stress distribution, the mining plan was optimized. The results indicate that under the influence of mining disturbances, the displacement of the tunnel roof increases non-linearly in four stages as mining progresses. The displacement of the main crosscut in the mining area is generally greater than that of the segmented horizontal tunnels, and the fastest growth stages vary among different mining schemes. In terms of stress distribution, the stress concentration in the side walls of both the segmented flat roadway and the main crosscut of the mining area is higher than that in the shoulders. Among these, the stress growth rate on the right side of the segmented flat roadway is significantly higher than that on the left side, exhibiting an asymmetric characteristic. Additionally, when using upward advance mining, the stress in the main crosscut of the mining area undergoes significant stage-wise sudden changes, while when using downward mining, the stress growth is relatively gradual. When the roadway width is increased from 4 m to 5 m, the increase in stress and displacement is small, but when increased from 5 m to 6 m, the width change significantly affects roadway stability. Therefore, considering both roadway stability and mining efficiency, the 5 m downward mining scheme better aligns with on-site safety production requirements. Field monitoring results further validate the reliability of parameter optimization. The research findings provide scientific basis and engineering references for the layout and stability control of deep tunnels.
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Combined Acousto-optic Characterization of Damage and Failure of Sandstone with Filled Frozen Fissures
Abstract:
There are complex physical and chemical changes such as water-ice phase transition, ice wedge effect and filler dissolution / crystallization in rocks in alpine regions, which lead to irreversible damage of rocks with filling fractures and seriously threaten the safety and stability of open-pit slopes and transportation infrastructure in alpine regions. In this article, the frozen fractured sandstone with filling (FSFF) is taken as the research object, and the influence of fracture length and fracture angle on the macroscopic mechanical properties, surface strain field and AE parameters of rock samples is studied by using acousto-optic mechanics technology. The results show that with the increase of crack length, the compressive strength of rock samples decreases continuously, and the crack propagation of rock samples is dominated by S1, S3 shear cracks and M-type tensile-shear cracks. When the fracture length is small, the sharp rise of AE ringing count of rock samples is concentrated in the fracture propagation stage. With the increase of fracture length, the sharp rise of AE ringing count of rock samples is concentrated in the elastic stage and the fracture propagation stage. With the increase of the fracture angle, the compressive strength of the rock sample decreases first and then increases, the AE ringing count in the rock sample increases sharply, and the distribution of acoustic emission events in the rock sample is more and more dispersed. The crack propagation of rock samples is dominated by S1, S2, S3 shear cracks and M-type tensile-shear cracks. The failure mode of sandstone with filling frozen fracture is mainly shear fracture. The research results can provide a theoretical basis for the engineering stability evaluation of fractured rock mass in cold regions.
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Surrounding rock design and stress analysis of composite roof cutting and pressure relief gob-side entry retaining
Abstract:
Aiming at the problem of surrounding rock control of gob-side entry retaining under the condition of water-rich composite roof, a set of collaborative control technology is proposed through theoretical analysis and engineering test. Firstly, the complex deformation mechanism of roadway surrounding rock under composite roof and water-rich geological conditions is analyzed, and the shortcomings of traditional support technology in dealing with these challenges are pointed out. An innovative scheme of using ultra-long anchor cable three-column vertical support combined with two-way shaped charge blasting to cut off roof stress transfer is proposed. At the same time, " one beam and four columns " hydraulic support is implemented in the dynamic pressure zone, and C concrete bottoming and grouting anchor cable reinforcement are used in the water spraying section. The engineering application shows that the technology significantly shortens the deformation period of surrounding rock by more than 40 %, effectively reduces the amount of floor heave, and realizes the stable control of gob-side entry retaining with water-rich composite roof. The research results of this paper not only provide important technical reference for non-pillar mining, but also provide new ideas and methods for safe and efficient mining of deep coal resources.
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Study on the Strategic Layout of the Entire Industry Chain of Deep-sea Mineral Resources with the Goal of
Abstract:
The "dual carbon" goals have driven explosive growth in the renewable energy industry, leading to surging demand for critical metals such as copper (Cu), nickel (Ni), and cobalt (Co). Deep-sea minerals, serving as a strategic supplement to land-based resources, have emerged as a critical pathway to securing supply chains. Addressing China’s high external dependency on critical metals and acute supply chain vulnerabilities, this study systematically investigates the strategic layout of the entire industry chain for deep-sea mineral resource development. Building on the vast potential of international seabed resources such as polymetallic nodules, cobalt-rich crusts, polymetallic sulfides, and deep-sea rare earths, and leveraging China’s "first-mover advantage" of exclusive exploration rights and preference mining rights over five international seabed areas, a competitiveness analysis highlights China’s strengths in exploration scale and manned submersible technologies. However, persistent bottlenecks include reliance on imported core mining components and insufficient influence in international environmental standard-setting. The research proposes a framework anchored in "top-level strategic planning—green technology innovation—industrial chain coordination—global governance leadership." Key pathways encompass establishing a national collaborative mechanism to advance low-disturbance mining technologies, building a distributed industrial chain spanning "offshore mining—coastal preprocessing—inland refining," and spearheading international standards for sustainable deep-sea mining. Phase-specific milestones are defined: completing full-system sea trials in mining areas by 2030 and achieving an annual production capacity of 20 million tons of dry nodules by 2040. By integrating technological breakthroughs and strategic engagement in regulatory frameworks, this approach provides a strategic blueprint for China to establish a self-reliant, secure, and competitive deep-sea mineral supply system.
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Design and Research of High Power Permanent Magnet Generator for Wind Power Large Base in Mining Area
Abstract:
In response to the challenges posed by the spatiotemporal randomness of wind resources in large-scale wind power bases in mining areas for the design of high-power wind turbines, a study was conducted on the adaptive design and optimization of a 6.0 MW permanent magnet wind turbine based on measured data from a wind farm in a mining area in Inner Mongolia. Based on multidimensional wind measurement data mining, the joint probability distribution of wind speed, temperature, and duration was quantified, and a dynamic load spectrum model reflecting actual wind conditions was constructed. With the goal of improving electromagnetic performance and reducing material costs, the coil size and permanent magnet size were synergistically optimized. The electromagnetic scheme was validated through finite element simulation, achieving the design goal of efficiency ≥ 98%. The test results of the two prototypes developed show that the error between their no-load and load characteristics and simulation results is within 3%, which verifies the high accuracy of the model; The temperature rise test revealed the temperature field distribution law of the motor under complex operating conditions, and based on this, a thermal management control strategy was established; The research has formed a complete technical chain of "data-driven modeling multi-objective optimization simulation verification prototype testing", which not only provides solutions for specific wind farms, but also provides universal theoretical support and practical guidance for the engineering application of high-power permanent magnet wind turbines in large-scale wind power base.
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A comprehensive energy scheduling model for photothermal coupling under the conditions of exploration and production energy consumption in mining areas
Abstract:
The comprehensive energy system for mines aims to address the spatiotemporal interweaving characteristics of high energy consumption production loads such as drilling rigs, ventilation, and drainage during mining exploration and extraction, as well as building heating and hot water living loads, and the current situation of unique resources such as mine water waste heat and associated gases in mining areas. The research aims to construct an integrated scheduling scheme to improve energy efficiency and low-carbon level. A mining integrated energy system optimization scheduling model that integrates photovoltaic thermal power stations and multi-source heat pumps has been proposed. This model achieves spatiotemporal energy transfer through photothermal molten salt storage, and collaborates with mine specific heat pump groups such as water and gas sources to construct an electric thermal collaborative supply network that adapts to the pace of mining production. And a multi-objective particle swarm optimization algorithm was designed for this model to simultaneously optimize the system"s operational economy and carbon emissions. The experiment shows that the weekly operating cost of the mine"s energy system has been reduced to 331700 yuan, a decrease of 20.9% compared to traditional strategies. The total carbon emissions are 39.44 tons, a reduction of 29.8%. The consumption rate of renewable energy reaches 92.54%. Especially, this system effectively ensures stable heating in the mining area, with temperature fluctuations controlled within ± 1.2 ℃; The utilization rate of the solar thermal storage device reached 92.17%, and the average performance coefficient of the heat pump group increased to 4.47. The results indicate that the strategy can fully integrate and utilize multiple sources of energy in the mining area, effectively improve the economic and environmental benefits of the mining production system, and provide key technical support for the construction of green mines.
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Experimental Study on Crack Propagation Behavior and Damage Characteristics of Jointed Rock Bridges under Inclination Effect and FRACOD Simulation
Abstract:
? Underground rock masses often contain joints at different angles with various infillings. The crack propagation and failure behavior of rock bridge structures directly influence the stability of underground rock engineering. This study systematically investigates the crack propagation behavior and damage mechanism of filled jointed rock bridge structures under different inclination angles through uniaxial compression tests on filled jointed red sandstone specimens with varying angles, acoustic emission (AE) parameters (ring count, rise time, amplitude, duration), and FRACOD numerical simulation. The results indicate that the stress-strain curve exhibits three stages: compaction, elastic deformation, and stress drop (post-peak), with stress surges occurring near the peak due to slip and crack initiation. AE signals significantly intensify before and after the peak strength, and the cumulative ring count shows a step-like increase; the sudden jump points can effectively identify the crack initiation critical point. RA-AF analysis reveals that shear cracks are predominant at a 30° inclination angle, while tensile failure is dominant at a 45° inclination angle. The crack propagation mode transitions from tensile-dominated to tensile-shear composite and then back to tensile-dominated as the inclination angle increases. FRACOD simulation results demonstrate that as the stress ratio (vertical stress/horizontal stress) decreases, horizontal stress significantly suppresses the range of crack initiation and propagation. The increase in horizontal stress significantly alters the failure mode of the rock mass by inhibiting tensile crack propagation. The findings reveal the mechanism by which joint inclination angle affects the crack propagation and damage evolution of rock bridge structures, providing a theoretical basis for stability analysis in deep underground rock engineering.
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Systematic Analysis and Validation of Backfill Strength in Tungsten Mine Stopes
Abstract:
The strength of the first-step backfill in the post-abandonment backfilling method is crucial to the stability of the second-step mining. This paper considers both safety and economy and conducts a comprehensive and systematic analysis and verification of it. Firstly, the strength requirements of the backfill are preliminarily calculated by combining the engineering analogy method, empirical formula method and theoretical model method. Secondly, the backfill proportioning tests are carried out to obtain the strength and fluidity parameters of the backfill with the tailings mass concentration of 70%, 72%, 74% and the cement-to-sand ratio of 1:4, 1:8, 1:12, 1:20, 1:25. Then, numerical simulation calculations are conducted on the backfill under 1.5MPa to 3.0MPa to obtain the safety indicators. Finally, the multi-objective ideal point method is used for comprehensive decision-making, combined with economic indicators, to obtain the optimal backfill strength scheme, and on-site core sampling verification is carried out. The research results show that the strength of the first-step backfill should not be less than 1.5MPa, and the strength of the backfill is positively correlated with the cement-to-sand ratio and concentration, and negatively correlated with the slump. Moreover, the backfill slurry with a concentration of 74% has better filling performance. Considering economic factors comprehensively, the optimal backfill strength is 2.0MPa. The on-site core sampling strength qualification rate is close to 80%, and the stability of the second-step stope after mining is good.
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Optimal Design of Fiber Bragg Grating Safety Monitoring Model for Mine Exploration
Abstract:
To enhance the problem-solving ability of Fiber Bragg Grating sensors in the mine safety monitoring system to the cross-sensitivity of temperature and strain, an efficient monitoring model was constructed by adopting the double grating compensation method and the particle swarm optimization-Gaussian process regression algorithm. The experimental results show that the proposed method has advantages in both data fitting and prediction accuracy. The monitoring system has achieved high-precision measurement of temperature and strain data in the mine environment. The lowest monitoring error is only 0.04mm, and the fit degree R2 value reaches 0.912, indicating the superiority of the system in wavelength drift prediction. By comparing the performance of fiber Bragg grating sensors, the superiority of fiber Bragg grating sensors in terms of data acquisition accuracy and speed is emphasized. The accuracy rate is as high as 0.961, and the data transmission speed is higher than that of photosensitive sensors and electronic sensors. This research provides new theoretical basis and technical support for enhancing mine safety, and at the same time lays a foundation for the future development of intelligent monitoring systems.
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A dynamic diagnosis method for mine reclamation soil quality integrating Swin-Unet and Grad-CAM
Abstract:
To solve the problems that the existing diagnostic methods are difficult to capture its long-term change patterns, the evaluation of reclamation effects lags behind, and the diagnostic results of soil quality lack interpretability, a dynamic diagnostic model for mine reclamation soil quality based on Swin-UNet and gradient-weighted class activation mapping visualization technology is proposed in this study. This model extracts soil image features through Swin-UNet, suppresses noise and highlights key features with the help of extrusion and excitation network modules, optimizes the model structure by pruning algorithm to reduce computational complexity, and finally improves the interpretability of diagnostic results by using gradient-weighted class activation mapping. Experiments show that the accuracy and precision rates of the research model in identifying soil quality grades are 96.1% and 97.6% respectively, the determination coefficient for identifying the content of available potassium is 0.983, and the recognition rate of soil pollution areas is 98.4%. All the above experimental data are superior to the comparison model, fully demonstrating the feasibility and superiority of the research model. In addition, the study also quantified the correlation degree between influencing factors and soil quality through this model, improving the reliability of soil quality diagnosis results and providing a new method for related research.
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The Application of Mechanized Upward Infill Mining Method in a Soft and Fragmentable Thick Orebody of a Gold Mine
Abstract:
In view of the occurrence of weak broken thick orebody in a gold mine, mechanized upward infill mining method was proposed, this study introduced its stope layout, cutting engineering and mining technology of the mining method. This study established six sets of stope structural parameters through orthogonal experiments, FLAC3D numerical simulation software was employed to analyze its stope stability, under the condition of ensuring the safety and stability of the stope, the structural parameters should be maximized to improve the technical and economic indexes. Results indicate that compressive stresses and tensile stresses primarily concentrate at the roof-floor junctions of the stope sidewalls, both stress types exhibit symmetrical distribution patterns; Displacement values in both the stope roof/floor and hanging wall surrounding rock increase with larger drift width and height increments, though overall displacements remain minor; Excessive drift dimensions lead to significant stress concentration in the orebody roof and surrounding rock; The optimal structural parameters were identified at a drift width and height of 5m. The application results of site test show that the stope production capacity is 220t/d, the stripping ratio is 24.5m/kt, the loss rate is 6.2%, and the dilution rate is 8.3%, the significant economic benefits have been achieved.
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A Detection Algorithm for Hydraulic Support Protection Plates in Coal Mines Based on Improved YOLOV8n
Abstract:
To address the low detection accuracy and poor real-time performance of hydraulic support shield beam detection in complex underground coal mine environments, an improved YOLOv8 detection algorithm named CMH-YOLO is proposed. Due to confined underground spaces and limited camera angles, traditional downsampling operations cause severe feature loss for distant small shield beams. Therefore, CMH-YOLO first introduces SPDConv in shallow networks, encoding spatial information into channel dimensions to preserve small object details. A lightweight C2f_MSA module is designed, integrating Large Kernel Separated Attention for long-range dependency modeling with Efficient Channel Attention for adaptive feature selection, enabling simultaneous capture of multi-scale shield beam features. For the feature blurring and occlusion caused by high dust environments, a C2f_DRFE dust-robust feature enhancement module is constructed, employing multi-scale dilated convolutions to expand receptive fields and deformable convolutions to adaptively avoid dust-occluded regions. Finally, Inner IoU loss function is adopted to improve bounding box regression accuracy through auxiliary box mechanisms. Experiments on a coal mine hydraulic support dataset containing 20,045 labeled images show that CMH-YOLO achieves 97.9% mAP@0.5, 93.8% precision, and 94.5% recall, improving by 1.7, 2.7, and 1.6 percentage points over baseline YOLOv8n respectively, while maintaining model efficiency. The algorithm effectively addresses small object detection, multi-scale adaptation, and dust interference challenges in extreme environments, providing a reliable real-time detection solution for coal mine hydraulic support safety monitoring with significant engineering value for preventing roof accidents and ensuring miner safety.
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Mechanical properties and permeability evolution of double-fissured limestone specimens with varying fissure dip angles before and after filling under complete stress–strain condition
Abstract:
This study investigates mechanical properties and permeability evolution in double-fissured limestone during complete stress-strain processes before and after grouting. By conducting full stress–strain seepage tests on 45° double-fissured limestone before and after grouting under confining pressures of 10, 20, and 30 MPa, the study reveals the evolution of strength and permeability under coupled stress–strain–seepage conditions. The analysis shows that the compressive strength of both ungrouted and grouted specimen increases with increasing confining pressure, while their permeability decreases as the confining pressure increases. Grouting significantly enhances strength. Compared to ungrouted specimens, grouted ones show limited pre-peak permeability reduction but abrupt post-peak decreases. Permeability peaks post-failure and minimizes during linear-elastic deformation. Grouting suppresses dual-peak permeability phenomena observed in ungrouted specimens.
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Macro and Microscopic Failure Mechanisms of Sandstones under Heating-Cooling Treatments
Abstract:
As an emerging direction for green energy development, mine geothermal systems pose new challenges to the stability of surrounding rock due to the alternating thermal–cooling cycles during operation. To systematically reveal the multi-scale response mechanisms of surrounding rock under repeated thermal disturbances, this study focuses on dense sandstone from a mining area in Shanxi Province. A comprehensive observation framework is established, encompassing macroscopic property evolution, mechanical behavior, microstructural damage, and mesoscopic crack simulation. Experimental results demonstrate that under the coupled influence of temperature gradients and cycle numbers, sandstone exhibits significant degradation in both elastic modulus and peak strength, accompanied by a composite failure mode of "crack coalescence – local slip – structural detachment." Scanning electron microscopy reveals a progressive damage process characterized by "intergranular bond breakage – microcrack propagation – skeleton disintegration." Meanwhile, mesoscopic discrete element simulations capture the initiation sequence and tensile–shear crack patterns, quantitatively illustrating the evolution of structural damage from boundary zones to the interior. These findings elucidate the temperature cycle-induced failure processes across macro–micro–meso scales, filling critical knowledge gaps in the thermomechanical damage response of sandstone, and provide theoretical insights for predicting rock stability and conducting multi-physics coupling simulations under mine geothermal development conditions.
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Study on Flow Channel Improvement and Internal Flow Characteristics of Deep-Sea Drilling Hydraulic Compensators
Abstract:
The hydraulic compensator in deep-sea drilling equipment plays an indispensable role in balancing internal and external pressure and adjusting the oil supply rate of the machine during drilling and mining processes. Its working principle is to utilize seawater pressure to compensate for the volume change of hydraulic oil caused by deep-sea pressure, environmental temperature difference, and other factors, thereby preventing seawater from backflowing and causing corrosion to the drilling equipment. Based on Ansys software, this paper conducts a mechanical analysis on the volume of two compensators with different shapes. It uses AMEsim to simulate their hydraulic circuits, adds components such as pressure reducing valves, check valves, and relief valves to the original hydraulic circuit model, designs a hydraulic circuit under the active working state, and conducts a comparative analysis of the flow velocity before and after the improvement. In addition, it analyzes the internal flow field with different parameters under deep-sea working conditions, such as rubber with different shapes (number of folding layers) and inlet/outlet sizes. Finally, a brand-new hydraulic compensator is designed based on the pressure and temperature of the marine environment. The research results show that the compensator with a multi-fold shape and 20mm inlet/outlet size has the optimal performance. Its hydraulic system can provide a larger flow rate in a shorter time and has a stronger adaptive adjustment capability for flow transients.
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Study on the Energy Evolution and Damage Law of Salt Rock under Different Cyclic Loading and Unloading Rates
Abstract:
Under the impetus of the current carbon neutrality strategy, salt rock serves as a key geological carrier for low-carbon engineering. Research on its mechanical response and damage law under cyclic loading-unloading conditions is crucial to the safe operation of salt cavern energy storage repositories. To reveal the energy evolution law and damage mechanism of salt rock under different loading-unloading rates, uniaxial cyclic loading-unloading tests at various rates were carried out on salt rock from a proposed compressed air energy storage (CAES) salt cavern in China. Mechanical monitoring, real-time acoustic emission (AE) monitoring, and energy analysis methods were adopted to explore its mechanical response and damage evolution process. The results show that: (1) Salt rock exhibits significant viscoplasticity under uniaxial cyclic loading-unloading conditions, and the higher the loading-unloading rate, the lower the compressive strength; (2) With the increase of loading-unloading cycles, the input work increases continuously, the proportion of elastic energy first rises and then decreases, the dissipated energy increases steadily, and the latter stage is dominated by dissipated energy; (3) AE activity is positively correlated with the stress loading level. At low loading rates, it manifests as low-energy and high-frequency micro-fracture activities, while at high loading rates, it shows the characteristics of high-energy and low-frequency macroscopic crack propagation; (4) The damage evolution can be divided into three stages: slow initial stage, stable middle stage, and accelerated late stage. Moreover, the higher the loading rate, the greater the damage degree at the same stress level. The research results can provide theoretical and design bases for the optimization of injection-production rates and long-term stability assessment of salt cavern energy storage repositories.
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Numerical simulation study on moisture distribution characteristics of plate-and-frame filter presses under multi-particle size systems
Abstract:
Establishing a research framework to investigate the mechanisms of particle motion and the influence of feed parameters on the moisture distribution of filter cakes is a crucial foundation for optimising coal slurry dewatering processes. Based on the Eulerian multiphase flow model and the multi-scale characteristics of coal slurry particles, a three-dimensional dynamic filtration numerical model of plate and frame filter press was constructed to systematically investigate the mechanism of particle movement and the role of feeding parameters on the moisture distribution of the filter cake. The study indicates that fine particles (<0.1 mm) are primarily influenced by fluid drag force, exhibiting an early ‘permeation’ phenomenon characterised by streamline dispersion (disappearing after 120 seconds) and forming a dense outer shell accounting for 80% of the volume fraction on the filter cloth surface. Coarse particles (>0.1 mm) primarily settle due to gravity, aggregating in the lower and middle sections of the filter chamber to form a supporting skeleton. Feed concentration significantly affects filter cake structure: at low feed concentrations (30%), layering of fine and coarse particles leads to ‘sandwich’ moisture accumulation in the middle and upper regions; a 40% feed concentration achieves uniform particle distribution and efficient dewatering; at high feed concentrations (>50%), reduced fluid carrying force causes particles to settle synchronously, forming a uniformly dense but moisture-dispersed filter cake. Additionally, when the filter chamber thickness exceeds 38 mm, the densification of the filter cake outer layer combined with insufficient internal drainage pressure jointly induces a central ‘sandwich’ phenomenon, which shifts toward the axis as thickness increases. These findings provide a theoretical basis for optimising filter press process parameters.
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Research and Application of the "One Map" System for Safety Production Early Warning in Non-Coal Mines
Abstract:
In response to the problems existing in the monitoring and early warning of mine safety production, such as the fragmentation of multi-source heterogeneous data, the lag in risk identification and the insufficient coordination of supervision, a "one-map" system for mine safety production early warning based on multi-source data fusion technology has been studied and constructed. The system, through core technologies such as data fusion, real-time monitoring, and risk four-color chart display, has designed a dual-track architecture featuring the collaborative coupling of the government regulatory end and the enterprise regulatory end: the government end focuses on macro compliance supervision and emergency command, while the enterprise end emphasizes the closed-loop rectification of micro risk hazards. Through a collaborative mechanism, the two form a new integrated closed-loop supervision model. Research results show that the "One Map" collaborative early warning system has improved regulatory efficiency by approximately 20%, and the accuracy of risk assessment has reached over 90%. The time for handling potential risks at the enterprise supervision end has been shortened by 30%, and the accident rate has decreased by 15%. The data utilization rate of the data collaboration application end has increased by 20%, providing an effective technical implementation path for intelligent supervision of mines and having reference value for promoting the digital transformation of the industry.
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Analysis of the Applicability of Coal Gasification Slag Paste Filling Material and Its Influence on Groundwater Quality
Abstract:
A large amount of coal gasification slag is produced during the mining and utilization of coal resources. The efficient and green disposal of gasification slag is one of the problems to be solved in the coal field. In this paper, the working performance and mechanical properties of coal gasification slag paste filling materials were studied by orthogonal test, and the differences between them and standard specifications were compared. The range analysis method was used to determine the optimal ratio of slag to paste ratio of 2.5 : 1.5, ash mixing ratio of 2 : 2, slurry mass concentration of 76 %, and the coal gasification slag content was 11.7 %. The soaking test of the material was carried out by static leaching method, and the leaching liquid indexes in different periods were detected. The results showed that the indexes of the leaching liquid could reach the balance in the later stage and meet the basic requirements of groundwater quality, which did not exceed the class III water quality standard. Using the F value method, it was found that the comprehensive evaluation of groundwater quality in different days of soaking was mainly ' good '.Although the water quality decreased with the increase of soaking days, the overall situation was still in a good state. Compared with the traditional filling material, the cost of coal gasification slag paste filling material is reduced by 16 %, and the material performance is significantly improved. This study provides an important basis for the application of coal gasification slag paste filling technology, and is of great significance for realizing the resource utilization of coal-based solid waste and protecting groundwater resources.
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Research on Blasting Dynamic Response and Parameter Optimization in Near-surface Mining
Abstract:
In order to solve the problem that the cultural relics area and cultural relics group distributed directly above the ore body in a copper mine may be affected by blasting vibration due to mining, this paper carries out a systematic study in order to realize protective mining. Firstly, the relationship between the surface cultural relics area and the ore body is analyzed, and the maximum allowable blasting vibration velocity is determined based on the blasting vibration safety criteria at home and abroad, and the maximum single-stage blasting explosive amount within the allowable distance of blasting safety is obtained based on the M.A. Sadowski empirical formula. Subsequently, the blasting simulation is carried out on the four middle sections of 1945m, 2020m, 2095m and 2245m closest to the surface of the whole life cycle mining through numerical simulation, and the rationality of the maximum single-stage blasting explosive volume is verified. At the same time, the blasting vibration test is carried out on the surface arrangement of measuring points during the blasting of the representative middle section of the underground, and the test results show that the blasting seismic waves have no effect on the surface structures. Finally, the SSA-Elman neural network Y-directional blasting vibration prediction model is constructed by collecting the on-site blasting vibration data, and its accuracy is verified by comparing it with the traditional Elman neural network model. The research results provide a basis for the design of other middle section blasting parameters of the copper mine, ensure the safety of cultural relics, and realize protective mining.
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Research on the Strength Characteristics and Prediction of Ultrafine Full Tailings Fiber-filled Backfill in a Gold Mine
Abstract:
A certain gold mine faces the issue that the uniaxial compressive strength of ultra-fine all-tailings backfill fails to meet the requirements for stoping backfill. To enhance backfill strength and satisfy stoping backfill demands, steel fibers, polypropylene fibers, and steel-polypropylene hybrid fibers investigate as strength-enhancing materials for the backfill. Systematic experiments comprehensively explore the effects of fiber type, dosage, and curing age on backfill strength. Based on experimental data, an interpretable strength prediction model integrating Gaussian Process Regression (GPR) and Shapley Additive Explanations (SHAP) develops to achieve efficient and accurate prediction of the backfill"s compressive strength. Research findings indicate that under 3-day to 7-day curing conditions, steel fibers exhibit the most significant strengthening effect, with a strength improvement rate reaching 69.34%. When cured for 28 days, polypropylene fibers show the optimal strengthening performance, with a strength improvement rate of 18.00%. All fiber systems demonstrate the best strength improvement effect when the fiber dosage is 0.3%, and a typical nonlinear relationship exists between fiber dosage and strength, characterized by "promotion at low dosage and inhibition at high dosage”. Furthermore, the established strength prediction model presents excellent prediction performance, with the average error of strength prediction controlled within 10%. SHAP analysis accurately quantifies the influence weights of fiber type, dosage, and curing age on strength, providing clear insights into the contribution of each factor. These research results offer a quantitative basis for the mix proportion design of fiber-modified backfill and promote the intelligent development of mine backfill engineering.
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Research on Enhanced Blasting Technology with Water Stemming in High-Altitude Open-Pit Metal Mines
Abstract:
Currently, high-altitude open-pit metal mines face significant issues with deep-hole blasting, such as uneven rock fragmentation and a high boulder rate. To address these problems, this paper proposes an enhanced blasting technology using water stemming in open-pit mines. Numerical simulation methods were employed to study the temporal and spatial variations of equivalent stress and damage in rock after explosive detonation with fine sand stemming and water stemming. The mechanism of water stemming enhanced-blasting was analyzed, and blasting crater experiments were conducted at the Julong Copper Mine to verify the accuracy of the numerical simulations. The results indicate that with traditional fine sand stemming blasting, the equivalent stress propagates upward slowly and unevenly, causing most of the blasting energy to concentrate at the bottom of the borehole, resulting in insufficient fragmentation of the upper rock mass. In contrast, with water pressure stemming blasting, due to the incompressibility of water and its excellent stress transmission properties, the blasting stress propagates rapidly and uniformly through the water column to the middle and upper parts of the borehole, leading to effective fragmentation of both the upper and lower rock masses. Compared to fine sand stemming blasting, the maximum surface length, crater depth, and crater volume of the upper water pressure stemming blasting increased by 13.33%, 12.07%, and 47.61%, respectively. This study holds significant research and practical value for efficient blasting and mining in high-altitude open-pit metal mines.
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Exploration of New Reagents for Low Grade Copper and Sulfur Recovery from a Certain Iron Ore Tailings
Abstract:
An iron tailing from an iron ore dressing plant in Hubei province contain 0.06% Cu and 10.24% S, with gangue minerals mainly composed of quartz and calcium silicate. To achieve efficient recovery of copper and sulfur from this tailing, exploratory tests were conducted with new reagents using the flowsheet of "bulk flotation first, then separation flotation" process. The results show that with a one roughing, one cleaning, one scavenging bulk flotation circuit and a one roughing, two cleanings and one scavenging flotation circuit for copper-sulfur separation, under a grinding fineness of 64.8% passing 0.074 mm, the bulk flotation stage employed a novel reagent combination of the new collectors BK916 + BK606 with synchronous addition of butyl xanthate as the collector and 2# oil as the frother. In the separation flotation stage, hydrated lime was added in stages as a depressant. This process yielded a copper concentrate with a Cu grade of 20.849% and Cu recovery of 57.20%, as well as a sulfur concentrate with an S grade of 34.08% and S recovery of 35.69%. Compared with the current reagent regime, this approach significantly improved the recovery rates of copper and sulfur. The findings provide valuable theoretical reference for the efficient recovery of other similar low-grade copper- and sulfur-bearing iron tailings.
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Disaster prevention and ecological restoration of open-pit coal mines under the guidance of dual carbon targets Research progress and transformation path
Abstract:
The dual carbon goals have set dual requirements for low-carbon transformation and ecological protection for the sustainable development of open-pit coal mines. As core issues, geological disaster prevention and ecological restoration need to adapt to new development needs. In response to the contradiction between energy security and low-carbon development faced by open-pit coal mines under the dual carbon goals, this article systematically explores the research progress in geological disaster prevention and ecological restoration. In the field of geological disaster prevention, it analyzes the evolution of traditional disaster characteristics and the emergence of new disasters under the guidance of low-carbon development, and summarizes the application achievements of energy-saving monitoring technology, carbon footprint-oriented early warning models, and green support technologies. In terms of ecological restoration, it summarizes the current development status of research on the carbon sink function of vegetation-soil systems, low-carbon restoration technologies, and carbon sink evaluation methods. On this basis, the article further analyzes existing technical bottlenecks (conflicts between traditional technologies and low-carbon goals, coordination challenges between carbon sink efficiency and engineering stability, insufficient technology integration), management mechanism deficiencies (cross-departmental policy barriers, unclear responsibilities of stakeholders, lack of regional collaboration, and separation of carbon sink and disaster risk assessments), and insufficient policy support (dispersed policy systems, disconnected standards, lack of incentive and restraint mechanisms, and lagging policy updates). Finally, it outlines three transformation paths: technology (building a low-carbon collaborative technology system), management (establishing a carbon-oriented collaborative mechanism), and policy (improving the low-carbon support and guarantee system), providing theoretical references for open-pit coal mines to achieve coordinated development of "disaster prevention-restoration promotion-carbon sink enhancement".
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Research on Scheduling Optimization of Underground Metal Mines Based on Monte Carlo Simulation
Abstract:
The production scheduling of underground metal mines faces severe challenges from multi-source uncertainties such as geological conditions, equipment status, and safety risks. Traditional deterministic scheduling methods struggle to ensure the robustness and efficiency of the system. To address this, an underground metal mine scheduling optimization model based on Monte Carlo simulation (MC-MOO) is proposed. First, a probability distribution model for multi-source uncertain factors is constructed. Then, by integrating Monte Carlo scenario simulation with the NSGA-II multi-objective optimization algorithm, a closed-loop solution framework of "probability modeling - scenario generation - multi-objective decision-making" is established to comprehensively optimize scheduling costs, production stability, and equipment load balance. Case studies show that compared with the traditional deterministic model, the MC-MOO model can effectively reduce the total cost by 5.97%, and improve production stability and equipment load balance by 41.82% and 23.61% respectively. It provides an effective modeling and solution paradigm for intelligent mine scheduling in an uncertain environment.
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Characterization of Temporal and Spatial Coupling of Dynamic Tunnel Wind Temperature Field Based on Gauss-Newton Method
Abstract:
To address the unresolved spatiotemporal coupling mechanisms of air temperature fields in dynamic excavation roadways for thermal hazard control in deep high-temperature mines, this study develops a three-dimensional heat transfer model for dynamic tunneling processes. By introducing the dimensionless time FoV (characterizing excavation velocity) and the conventional dimensionless distance X, a spatiotemporal binary relationship Θ(FoV,X) is established to describe the temperature field. The Gauss-Newton method is employed for iterative inversion to derive the coupled spatiotemporal dimensionless temperature relationship, thereby revealing the nonlinear regulatory mechanism of inlet air temperature on thermal hazard mitigation. Key findings include: (1) The dimensionless temperature evolution follows an exponential-quadratic time-varying relationship (MRE=1.1%), with temperature gradients positively correlated to spatial distance and negatively correlated to time. (2) While low-temperature ventilation achieves remarkable cooling efficiency, prolonged operation leads to thermal equilibrium between airflow and surrounding rock, causing a 26.3% decay in cooling efficiency, necessitating integrated strategies combining rock thermal regulation and localized refrigeration for sustainable cooling. (3) Reduced inlet air temperature intensifies nonlinear thermal variations, increasing the spatiotemporal coupling model’s MRE from 1.1% to 1.81%, yet remaining within engineering accuracy thresholds (MRE < 2%). (4) As the inlet air temperature decreases, the wind temperature response in the near headland area is the most sensitive, and the temperature drop is 1.4 times higher than that in the exit area of the roadway, and furthermore, the headland wind temperature threshold of 26 ℃ is used as a constraint to derive the dynamic design inlet air temperature, Td in(t), which satisfies the cooling requirements.
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Vision-Based Fast Localization Method for Onboard Material Center of Gravity
Abstract:
To address the need for real-time localization of the material's center of gravity during the unloading process of electric shovels in open-pit mines, this paper proposes a fast vision-based onboard method for locating the material's center of gravity. The method uses images captured by two cameras mounted on the side of the electric shovel. Median filtering is applied to suppress noise, and a combined approach utilizing HSV color space and Otsu's method is employed to segment the pile from the background. Subsequently, an edge detection algorithm extracts the pile contour, and the pile vertex is identified by exploiting its uniqueness. A three-dimensional model of the pile is reconstructed by integrating the material's angle of repose and the geometric constraints of the truck bed. The center of gravity coordinates are then calculated using the Monte Carlo method. Experimental results demonstrate that the pile vertex localization error is within 5%, with a localization time of less than 80 ms. This significantly improves measurement speed compared to traditional stereo matching methods. The pile center of gravity calculation time does not exceed 2.5 seconds, meeting the requirements for real-time unloading. This method provides reliable technical support for maintaining the loading balance of mining trucks.
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Research on the Mineral Processing of a Fluorite - Rare Earth Polymetallic Ore in Henan Province
Abstract:
The grades of CaF2 and REO in a fluorite - rare earth polymetallic ore in Henan Province are 21.73% and 1.56%, accompanied by small amounts of molybdenum and lead, with grades of 0.055% and 0.54%. The content of calcite and barite in the gangue components is high, and they are closely related to the embedding of fluorite and rare earth. In order to effectively solve the dual technical problems of separating fluorite, rare earth and calcium containing, barium/strontium minerals, fluorite and rare earth, as well as the comprehensive utilization of low-grade molybdenum and lead, research on the mineral processing has been carried out. The research results indicate that adopting the principle processing of "flotation enrichment of molybdenum and lead first, followed by recovery of fluorite and rare earths" and the beneficiation scheme of "fluorite and rare earths mixed flotation followed by" magnetic gravity "combined separation", combination use of modified fatty acid collectors CK-1 and CK-2, acidized water glass strengthens and suppresses calcium, barium/strontium containing gangue. The whole process closed circuit test obtained lead concentrate with Pb grade of 55.12% and Pb recovery rate of 33.63%, molybdenum lead intermediate ore with Mo grade of 3.28%, Pb grade of 7.95%, Mo recovery rate of 56.86%, Pb recovery rate of 13.03%, fluorite concentrate with CaF2 grade of 95.41% and CaF2 recovery rate of 79.32%, rare earth concentrate with REO grade of 56.83% and REO recovery rate of 45.10%, efficient recovery of fluorite and rare earths, as well as effective comprehensive utilization of molybdenum and lead, have been achieved, providing technical support for the development and utilization of this complex polymetallic mine.
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Preparation and performance research on grouting materials for typical large-water mining mines of the copper (cobalt) metallogenic belt in Central Africa
Abstract:
In response to the challenges of significant mine inflow and difficulties in grouting and water sealing in some underground mines within the Central African copper?cobalt metallogenic belt, which severely restrict the safe extraction of mineral resources, taking the Chambishi Copper Mine as a research object to develop efficient sealing materials and techniques applicable to this mine and other similar water-rich mines in the region. Five types of materials—local African clay, bentonite, a specific chemical material, domestically produced ultra-fine cement, and tailings—were selected for systematic laboratory tests. Multiple mix proportion schemes were designed to prepare slurries, and the physicochemical properties (viscosity, density, bleeding rate, plastic strength), setting time, and compressive strength of the hardened slurries were tested. The results indicate that local clay cake meets the requirements for slurry preparation. Modified clay slurry is suitable for large-scale ground curtain grouting and shaft curtain grouting projects, reducing material costs by 30%. Local bentonite satisfies the requirements for slurry preparation, and cement-bentonite slurry is applicable to deep, difficult-to-grout rock layers, showing 7 times greater injectability than traditional cement slurry in the “deep multi-layer sand zone”. Ultra-fine cement slurry is suitable for micro-fracture and behind-the-wall grouting, enhancing anti-seepage performance with high compressive strength of the hardened slurry. Chemical grout is effective for sealing defective boreholes, achieving instant setting with a strength exceeding 43 MPa, thereby efficiently preventing water inrushes caused by intersecting large-water-yield boreholes underground. Tailing slurry exhibits a relatively high bleeding rate and requires further experimental improvement with different additives.
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Research on Optimization and Renovation of the Deep Multi-Shaft Ventilation System in the Chambishi Copper Mine
Abstract:
As a typical deep mine in Central and Southern Africa, the Southeast Orebody of the Chambishi Copper Mine faces challenges such as long ventilation paths, high resistance, uneven air distribution, and difficulties in local ventilation, which seriously affect production safety and the underground working environment as mining depth and scope expand. Taking the Southeast Orebody as the research object, this study systematically investigates and measures the current status of its deep-level multi-shaft ventilation system and analyzes the major problems. Based on a rational division of ventilation zones, comprehensive optimization schemes are proposed from the perspectives of ventilation power, ventilation network, ventilation structures, and auxiliary ventilation systems, followed by comparative evaluation and selection of the optimal scheme. Using Ventsim software, a highly realistic three-dimensional visual model of the underground mine is established, and the optimized scheme is verified through network simulations.The results indicate that, after optimization, internal air leakage across the mine is reduced by nearly 50%, the effective air volume rate increases by 18%, the air supply to main level becomes controllable and adjustable, airflow in the deeper levels is significantly enhanced, and the overall underground environment is greatly improved.
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Stability Analysis and Reinforcement Parameters Optimization of False Roof Filling in Downward Drift Mining
Abstract:
In order to study the stability of stope false roof in downward drift filling mining of broken orebody, the quantitative relationship between the ultimate strength of the filling false roof and the thickness of the false roof was analyzed by constructing the stress model of the filling false roof, and the economic reinforcement ratio range of artificial false roof was determined. Meanwhile, numerical simulation experiments of stope mining under different in-situ stress and transverse reinforcement spacing were carried out, and the optimal transverse reinforcement spacing was optimized. The results show that the ultimate strength of the filling false roof decreases sharply at first and then increases slowly with the increase of false roof thickness, and the reasonable thickness of drift filling false roof is 4.0 m. With the increase of mining depth, the vertical displacement, stress and Von-mises equivalent strain of stope roof and floor also increase, while the tensile stress gradually decreases. The density of transverse reinforcement arrangement has a significant influence on the deformation and stress of the filling false roof and the surrounding rock of the drift. The denser the transverse reinforcement arrangement, the smaller the deformation and maximum tensile stress of the filling false roof. It is determined that the longitudinal and transverse reinforcement arrangement with 14 mm rebar spacing 300mm is the optimal scheme in terms of safety and economy.
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The impact and mechanisms of digital transformation on green innovation efficiency in Mining Enterprises
Abstract:
In the context of comprehensive and in-depth implementation of the “Dual carbon” development strategy, the synergistic development of digital transformation and green innovation has become the crucial for the sustainable development of mining enterprises. The paper focuses on the A - share listed companies in China"s mining industry from 2015 to 2023, takes them as research samples to carry out empirical analysis, aiming to explore the influence and inherent mechanisms of digital transformation on mining enterprises" green innovation efficiency. At the same time, from the regional perspective, it demonstrates the existence of the peer effect of digital transformation and its exogenous impact on the green innovation efficiency of mining enterprises. The research reveals that digital transformation exerts a notable positive influence on the green innovation efficiency of mining enterprises, and this conclusion still holds after endogenous test and robustness test. From the action - mechanism perspective, digital transformation can enhance the efficiency of mining enterprises by improving the efficiency of resource allocation, increasing information transparency and reducing the concentration of the supply chain. Heterogeneity analysis finds that in downstream enterprises of the supply chain, state - owned enterprises and non - heavily polluting enterprises, digital transformation exhibits a more pronounced positive impact on green innovation efficiency. Further analysis shows that there are obvious regional peer characteristics in the digital transformation of mining enterprises, and this phenomenon can substantially drive the enhancement of green innovation efficiency in mining enterprises.
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Process mineralogical analysis and flotation test study ofa low-grade lead-zinc ore in southern China
Abstract:
Process mineralogy analysis indicated that the valuable minerals in a low-grade lead-zinc sulfide ore from southern China primarily included galena, sphalerite and associated silver minerals, with other metallic sulfides dominated by pyrrhotite and pyrite. To achieve efficient comprehensive utilization of lead, zinc and silver resources, a systematic flotation experimental investigation was conducted on the ores. Through comparative tests, the appropriate grinding fineness and reagent scheme were determined. A sequential lead-zinc preferential flotation process was adopted, with both the lead and zinc circuits consisting of one roughing, two cleaning and one scavenging stage. The results of closed-circuit tests showed that under a grinding fineness of 56.6% passing 0.074 mm, the final lead concentrates with lead grade of 65.08% with a recovery of 91.32%, silver grade of 1323.80 g/t with a recovery of 79.28%, could be obtained, along with zinc concentrates assaying 41.70% Zn with a recovery of 85.96%. This process successfully achieved effective recovery of the major valuable elements from the low-grade lead-zinc-silver sulfide ores, providing a valuable reference for beneficiation of similar resources.
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Optimization and stability analysis of drift filling mining scheme in a copper-gold mine
Abstract:
s: In response to the challenge of mining high-grade ore bodies in deep, fractured and broken rock formations, this study explores the applicability of the cut-and-fill mining method in a copper-gold mine. Through core drilling, uniaxial compression and Brazilian splitting tests, combined with the Hoek-Brown and Mohr-Coulomb strength criteria, the key mechanical parameters of the surrounding rock and the backfill are obtained. Numerical simulations of the upward and downward cut-and-fill mining methods are conducted to analyze the displacement of the surrounding rock under the corresponding support conditions, and the preferred method is selected based on technical and economic indicators. The results show that the upward method is suitable for ore bodies with good to moderate rock stability, while the downward method is more suitable for extremely broken and unstable ore bodies. The compressive strength, tensile strength and elastic modulus of the surrounding rock are 85.48 MPa, 8.50 MPa and 45.50 GPa respectively, and those of the backfill are 0.55 MPa, 0.36 MPa and 0.45 GPa respectively. Numerical simulations indicate that both approach-type backfill mining methods result in relatively small total rock mass displacements, but the displacement distribution differs due to variations in the roof and floor strata. Economic comparisons show that the downward-filling method has higher costs (4.01$/t higher than the upward-filling method), but its support costs are lower (0.313$/t lower than the upward-filling method). Considering all factors, it is recommended to adopt the upward-filling mining method overall, with the downward-filling method used only in localized areas with highly fractured surrounding rock.
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Support Technology Optimization for Underground Roadways in Fractured Quartzite at Chambishi Copper Mine
Abstract:
The Southeast Ore Body of Kansanshi Copper Mine is in shallow metamorphic rock stratum, the surrounding rock joints and fissures are developed, and under the action of high geostress and long-term mining operation, which leads to obvious deformation of the roadway in actual production, and the frequent failure of the support system, especially in the form of roof crushing, anchor loosening, and anchor mesh collapsing and other problems. In order to solve the problem of poor support effect and adaptability of the existing pipe slit anchors, firstly, the research and analysis of rock mechanical properties are carried out for quartzite, the main rock body in the upper and lower pan of the ore body; secondly, based on the broken and deformed characteristics of typical roadways, and considering the applicability and mechanical properties of different types of anchors, it is proposed to use resin anchors instead of the original pipe slit anchors for the support of the roadways in the crushed perimeter rock, and 3DEC numerical simulation methods are used to establish a typical roadway model, which is a good method for the support system. Using 3DEC numerical simulation method, a typical roadway model is established to compare and analyze the displacement control effect and perimeter rock response characteristics of the two support schemes. Finally, it is determined that resin anchors can better control the deformation of the roadway than pipe-seam anchors through the field industrial test of resin anchors. The results show that resin anchors can significantly reduce the top plate subsidence, bottom plate bulging and gang wall inward extrusion, improve the stability of the roadway, and the support effect is better than the pipe slit anchors, which provides technical support and theoretical basis for the optimization of the support in the actual project.
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Research into the factors influencing the performance of vertical stirred mils based on DEM-CFD coupling
Abstract:
To obtain reasonable independent variables for establishing a model to predict the workability performance of a vertical stirred mil, univariate analysis was used to study the factors affecting workability. Firstly, the coupled DEM-CFD method was used to create a simulation model of a stirred mill and analyse the dynamic characteristics of the grinding media and slurry during. Secondly, the grinding experiments were carried out on the test platform. The reliability of the simulation model was verified by measuring drive torque values. Then, the simulation analyses the influence of the process parameters (rotational speed, media filling rate and slurry concentration) and the structural parameters (bottom gap, side gap and screw angle) on working performance (collision energy, torque and energy efficiency). This is achieved by establishing a quantitative relationship between the different factors and grinding performance indicators. Finally, the sensitivity analysis method was used to study the ranking of factors affecting the performance by the simulation results. The results showed that the factors affecting the energy efficiency and collision energywere ranked: screw angle, media fill rate, slurry concentration, side gap, screw speed and bottom gap. The factors affecting drive torque are ranked as follows: screw angle; slurry concentration; side gap; bottom clearance, screw speed and media fill rate. The above study provides a valuable foundation of theory for selecting the inputs required for a mill performance prediction model.
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Application of APAM Doped with Compounds in the Treatment of Fine-Particle Limestone Sand-Making Wastewater
Abstract:
Anionic polyacrylamide (APAM) is the most widely used flocculant in the mining and sand-making industry. However, adulteration during its production process is relatively common. To address the deterioration of flocculation performance caused by compound incorporation, flocculation-sedimentation experiments were conducted to systematically evaluate the effects of compound incorporation (e.g., sodium chloride, NaCl) on the flocculation performance of APAM. Techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and chemical titration were employed to characterize the properties of the doped flocculants. Combined with cost-benefit analysis, the economic implications of adulteration were quantified. The results indicate that APAM achieves optimal flocculation performance at a mass concentration of 0.1% and a dosage of 24 g/m3. High levels of compound incorporation (≥30%) severely impair the flocculation performance of APAM. Specifically, when the NaCl incorporation ratio reaches 50%, the median sludge particle size decreases from 95.3 μm to 41.3 μm, a reduction of 56.7%, and the sedimentation time extends to more than twice the original duration, leading to a significant decline in wastewater treatment efficiency. The established detection system, combining solid content determination, FTIR, XRD, and chemical titration, can specifically identify adulterated components. Economic analysis reveals that a 50% mass fraction of NaCl incorporation reduces the production cost of APAM by 48.75% but directly increases the overall wastewater treatment cost by 23.6%. The research findings provide a technical basis for quality control of flocculants and optimization of the water treatment system in the sand plant.
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The Study on Fault Prediction Method for Mining Excavator Engine Based on GWO-SVM
Abstract:
To improve the accuracy and stability of fault prediction for mining excavator engines under complex working conditions, a fault prediction model based on Grey Wolf Optimized Support Vector Machine (GWO-SVM) was constructed. Key operating parameters of the engine were collected using the Weichai “Zhiduoxing” diagnostic tool. Data preprocessing methods such as outlier detection and removal were applied, followed by feature selection using Pearson correlation analysis to build a well-structured and information-rich sample set. The grey wolf optimization algorithm was employed to adaptively optimize the penalty factor and kernel function parameters of the support vector machine, thereby enhancing the model’s nonlinear learning ability and generalization capability. A fault prediction experiment was designed and comparative tests were conducted under various typical fault conditions. The results show that the GWO-SVM model achieves higher prediction accuracy and stronger robustness in multiple fault type scenarios. Compared with the traditional support vector machine, the prediction accuracy improved by 9.9%, and the model maintained stable output even under small-sample disturbances and data fluctuations.
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Research on the Management and Control System for Mine Closure Effects in Non-Metallic Open-Pit Mines Under the Context of Green Mine Construction: A Case Study of Jining City, Shandong Province
Abstract:
Green mine construction serves as a pivotal driver for advancing ecological civilization in the mining sector. In the context of comprehensively promoting the construction of green mines, it is of great significance to explore replicable and promotable management models. Based on a combination of institutional reference and analogical reasoning, this study analyzes the connotation of the management system for the final effect of non-metallic open-pit mine mining, as well as the theoretical logic, implementation paths and advantages of constructing this management system. The research results show that: 1) The mine closure effect control system addresses the absence of intermediate regulatory layers in the vertical management of mineral resources. By prioritizing ecological restoration and land reuse objectives, it provides systematic guidance for the entire mining-rehabilitation lifecycle, shifting governance paradigms from post-mining remediation to proactive source control. This marks a fundamental transition in China's mine governance from passive compliance to strategic planning. 2) Drawing on the regulatory detailed planning methodology from territorial spatial planning, this research innovatively proposes establishing a Mine Closure Effect Control Plan (MCECP) tailored for mining and rehabilitation processes. This framework offers administrative and technical foundations for natural resource authorities to supervise subsequent mine planning. 3) Through a case-specific ("one mine, one policy") analysis of non-metallic open-pit mines in Jining City under varying conditions, this approach guides the scientific allocation of mining rights, orderly resource extraction, and the transformation of mine resource asset value. It harmonizes the relationship between resource development and ecological protection, effectively driving the high-quality development of green mines in Jining City. The mining completion effect control system offers valuable insights for comprehensively advancing green mine construction and contributing to the realization of a Beautiful China.
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Research on the Influence of Wind Speed on the Dust Migration Law of bench Blasting in Open-pit Mine
Abstract:
In order to solve the poor efficiency problem of blasting dust control in open-pit mine, the geometric model of the bench blasting flow field in the open-pit mine was established to explore the distribution characteristics influence of bench blasting flow field on the migration law of blasting dust under different wind speeds and determine the optimal blast dust capture time, the optimal position and the delay excitation time of water bag by using Fluent software. The results indicate that airflow develops a back-step flow pattern at the bench, forming distinct zones of high-speed and low-speed turbulence. As wind speed increases, the influence range of the high-speed and low-speed turbulent zones expands, and the time required for the flow field to become fully developed decreases. Concurrently, a structural vortex with a height matching the bench is formed. When the wind speed is constant, the blasting dust has a significant upward vertical movement and obvious horizontal movement in a short period of time, subsequently, the vertical upward movement becomes constrained while the horizontal travel distance increases substantially under the comprehensive influence of blasting impact, gravity and stable wind flow. Within the wind speed range of 2.4 to 4.4 m/s, the dust demonstrates prominent vertical movement within the first 4 seconds of blast and significant horizontal movement after 6 seconds of detonation. The vertical movement distance of the dust in the 4th second after blasting is 30m, and the horizontal movement distance of the dust in the 6th second after blasting is 22.6m~23.5m. Consequently, the optimal dust capture time is determined to be 4~6 seconds after blasting, and the optimal position of the water bag is determined to be between 15m~24m from the bottom line of the step slope, and the delayed excitation time of the water bag is Δt = Tf - Ts .
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Stability Prediction of Open-Pit Slope Based on WOA-CNN-LSTM Model
Abstract:
With the expansion of open-pit mining scale, the problem of slope stability has become increasingly prominent. Slope instability can threaten the safety of life and property and damage the ecological environment. Therefore, accurately predicting slope stability and taking preventive measures in advance is the core of achieving safe and efficient open-pit mining. Based on factor analysis, a WOA-CNN-LSTM (Whale Optimization Algorithm-Convolutional Neural Network-Long Short Term Memory, WOA-CNN-LSTM) slope stability prediction model was constructed. Six representative features, including cohesion c, internal friction angle Φ, slope angle β, slope height H, pore pressure ratio ru, and unit weight γ, were selected as the model discrimination indicators. The factor analysis method was used to eliminate the correlation among the six indicators, reduce the data dimension, and extract common factors. The extracted common factors were used as the input of the WOA-CNN-LSTM model, and the model was applied to a slope engineering case to verify its reliability. The results show that the principle of using the WOA algorithm to iteratively update and search for the optimal network parameters to optimize the CNN-LSTM network can effectively overcome the problems of the CNN-LSTM model being prone to falling into local optimal solutions and the influence of gradient descent on the prediction accuracy of slope stability, and improve the prediction accuracy and generalization ability of the model in slope stability prediction. This provides a new idea for slope stability prediction.
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Analysis and Research on the Roof Failure Mode and Influencing Factors of the Super-long Working Face in Xiaobaodang Coal Mine
Abstract:
The efficient exploitation of coal resources is of great significance for ensuring national energy security. Ultra-long working faces (with a strike length of ≥ 300 m) have become an important development direction for efficient coal mining due to their advantages such as high recovery rate and low tunneling rate. However, as the working face length increases, the roof fracture characteristics and mine pressure dctively guide the roof control of ultra-long working faces. Investigating 132205 ultra-long fully mechanized face at Xiaobaodang Colliery via integrated theoretical-numerical-field methodology and reveal the "middle priority fracture - migration to both sides" zonal fracture istribution patterns significantly differ from those of traditional working faces, and the existing theories are difficult to effemechanism formed by the coupling effect of advanced mining-induced fractures and primary fractures in the roof of ultra-long working faces. Its evolution goes through three stages: fracture of the middle peak zone, stress migration in the non-peak zone, and instability of the peak zones on both sides. Based on FLAC3D numerical simulation, the influence law of working face length on mine pressure manifestation is clarified: when the length increases from 250 m to 450 m, the roof subsidence increases several times, the initial pressure step distance decreases to 75 m, and the mine pressure distribution pattern changes from an "arch-shaped" single peak to an "M-shaped" triple peak. The field measurement data of hydraulic supports verify the reliability of the law. An innovative "zonal coordinated frame moving" control technology is proposed, which improves the uniformity of support resistance through differentiated strategies of group frame moving in high-stress zones and independent frame moving in low-stress zones. This has significant engineering value for promoting the large-scale development of shallow-buried coal seams in western China.
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Research and Application of Anti-Fatigue Driving Warning Systems in Ultra-High Altitude Mines
Abstract:
To address the challenges posed by the ultra-high-altitude mine driving environment—where existing anti-fatigue warning systems exhibit insufficient accuracy (below 95%) and high susceptibility to interference—we developed a high-precision, highly robust fatigue detection system to guarantee transportation safety. The proposed system fuses visual and electroencephalogram (EEG) features. FastICA is employed to remove ocular artifacts from EEG, and both EEG energy ratio features and sample entropy features are extracted. For visual analysis, YOLOX is used for face detection, combined with an improved PFLD algorithm to extract eye-state indicators, yawning features, and head-posture features. A multi-source information fusion decision algorithm based on Dempster-Shafer (D-S) evidence theory and Support Vector Machine (SVM) is designed to effectively integrate the probabilistic classification results from visual and EEG modalities. Field tests at the Las Bambas ultra-high-altitude mine in Peru demonstrated that the system achieves a markedly improved detection accuracy of 97.6 % and reliably captures key fatigue indicators. The conclusions are as follows: (1) Fusing visual and EEG features significantly enhances the accuracy and robustness of fatigue detection in ultra-high-altitude environments; (2) The fusion algorithm combining D-S evidence theory and SVM is the key to attaining 97.6 % accuracy; (3) The system provides reliable technical support for high-altitude mining operations, potentially reducing accident risk by approximately 15 %; (4) The approach offers new ideas for fatigue research in extreme environments.
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BACKBREAK CONTROL OF LARGE-DIAMETER LONG-HOLE BLASTING BASED ON AXIAL CHARGE STRUCTURE OPTIMIZATION
Abstract:
When using large-diameter long-hole caving method in underground mining, there are problems such as large backbreak, many collapsed blocks, and poor stability of the sidewall at the working face, which limits the further promotion and application of large-diameter long-hole mining technology. To control the blasting backbreak, this paper takes the three rows of large-diameter deep hole lateral blasting in an underground copper mine in Anhui as the engineering background to carry out the optimization study of axial charge structure. Firstly, LS-DYNA is used to establish numerical models of five axial charge structures, including 0.5m charge 0.5m air interval, 1m charge 1m air interval, 1.5m charge 1.5m air interval, 0.5m charge 1m air interval, and 0.5m charge 1.5m air interval, for the three rows of blast holes. By analyzing the damage distribution law and damage volume of the rock mass in different zones, the optimal charge structure for backbreak control of each row of boreholes is determined, and field tests are carried out to verify it. The results show that the axial charge structure changes the distribution of explosion energy, and thus changes the distribution laws of rock damage and breaking. Considering the rock breaking effect and backbreak control effect, it is recommended to use axial charge structures of 1m charge and 1m air interval, 0.5m charge and 1m air interval, and 0.5m charge and 1.5m air interval for three rows of blastholes. The optimized charge structure was applied to the field blasting test, and the collapsed blocks was significantly reduced. The wave velocity reduction rate of the rock mass near the blasting area was basically less than 10%, indicating that the rock mass had good integrity, small damage, and good backbreak control effect.
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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.
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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.
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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.
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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
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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.
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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 '.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 %.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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..
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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。
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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,?
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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.
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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.
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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.
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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.
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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.
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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．
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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°.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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..
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 %.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 %.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 %.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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 %.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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°.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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).
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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 %.
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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.
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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.
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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.
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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.
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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.
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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.
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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%.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Study on the Mechanism and Parameter Optimization of Non-blasting Intensive Drilling Top CuttingAbstract: