Abstract:To solve the problem of dewatering difficulty and low strength of backfill causing by the extremely fine unclassified tailings when tailings were used for cemented backfill preparation. Through the cemented filling test of waste rock-tailings, the particle size composition of filling aggregate was improved, and the influence of waste rock content on the flow and strength performance of filling material was studied. The results showed that compared with unclassified tailings cemented backfill, adding waste rock could significantly improve the flow performance of filling slurry and increase the conveying concentration. At the same cement-tailing ratio and slurry concentration, the strength of waste rock cemented backfill was higher than that of unclassified tailings cemented backfill. Therefore, the cement-tailing ratio and cement consumption was reduced and the surface waste rock was absorbed by waste rock cemented backfill. The industrial test was carried out in Jinchanghe mine of Yunnan Province. The filling parameters were determined, with 80% of the slurry concentration, 1:8 of the cement-tailing ratio was, and 60% of the waste rock content. The average compressive strength of in-situ coring was 3.36MPa, which met the design strength requirements of stope backfill.