The flotation tailings generated from a mine’s beneficiation process are treated and backfilled into underground goafs.In order to investigate the feasibility of using these flotation tailings for underground backfilling,relevant filling material tests were conducted.The experimental results indicate that the flotation tailings from the mine are relatively inert materials with few harmful components,making them suitable for underground backfilling.The fine particle fraction is relatively high,and the particle size distribution is uniform,although the gradation is not ideal; the settlement performance is moderate,and it takes approximately 60 hours for the settlement to complete;under a certain ash-sand ratio,both the initial and final setting times of the slurry decrease as the concentration increases;the strength of the filling body is positively correlated with the ash-sand ratio,concentration,and curing age.The optimal slurry transport concentration for backfilling materials is 57 %.If used for mining backfilling,the ash-sand ratio should be 1∶4.If solely used for goaf treatment,an ash-sand ratio of 1∶6 to 1∶8 would meet the backfilling requirements.The data and conclusions obtained from the experiments have direct guidance significance for mine filling operations.