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.