Collaborative backfilling technology using waste rock and full tailings in Maoping Lead−Zinc Mine

To promote the resource utilization of excavation waste rock and beneficiation tailings in Maoping Lead-Zinc Mine, experimental research was conducted on the performance of waste rock−full tailings cemented backfill materials with varying waste rock mixing ratios. Slump tests and uniaxial compressive strength tests were conducted to systematically analyze the influences of waste rock content, cement-tailings ratio, and slurry concentration on the flowability of backfill slurry and the mechanical properties of backfill. The results show that slurry flowability is mainly determined by slurry concentration, while waste rock content and cement-tailings ratio exert relatively limited effects. The uniaxial compressive strength of backfill increases with slurry concentration, and cement-tailings ratio. Mixing 20 %–40 % waste rock can optimize aggregate gradation and effectively improve the uniaxial compressive strength of backfill. However, when the waste rock content increases to 60 %, the uniaxial compressive strength of backfill decreases significantly. According to the comprehensive test results, when the cement-tailings ratio is 1∶4 or 1∶5, and the slurry concentration is no less than 75 %, the uniaxial compressive strength of backfill steadily exceeds 4.5 MPa, which meets the on-site engineering requirements. Accordingly, the optimal waste rock content for the mine is determined to be 20 %–40 %. Similarity simulation tests were carried out based on the above optimized mix proportions. The results show that under the construction process of laying waste rock prior to tailings slurry filling, the uniaxial compressive strength of backfill first increases and then decreases along the slurry flow direction. The research findings can provide technical references for mix proportion optimization of backfill, selection of on-site construction technologies in this mine, and collaborative filling utilization of solid wastes in similar mines.