Abstract:According to the selection of backfill cementing materials and the parameter design of backfill mixing ratio in the Yueshan copper mine, the comparison tests of backfill strength by using cement or by using a new cementing material in total tailings are carried out. The basic physical and mechanical properties of total tailings are studied first, and based on this, with the method of comprehensive tests, the experiments of uniaxial compressive strength of total tailing backfill samples with different cement-tailing ratio and slurry concentration are analyzed. The results show that the median particle size of total tailings, d50, is 0.0426mm, and the percentage of tailings particle size larger than 0.074mm is only 36.8%, hence, the total tailings are fine one. By using general cement, with the cement-sand ratio of 1:6 and the pulp density of 70%, the uniaxial compressive strength of cemented backfill is 1.32MPa for sample curing time of 28d, while by using a new cementing material which is 4.66MPa, i.e., 3.53 times as much as that of by using general cement. It is recommended to carry out industrial filling tests with slurry concentration of 68%~70% and new cementing material-sand ratio of 1:6~1:8. The results of industrial tests show that the strength of backfill samples in boreholes No.1 and No.2 can meet the requirements of filling techniques and the mining operation of Yueshan copper mine, as the strength is still surplus. In order to reduce the amount of new cementing materials in backfill and thus to save the filling cost, it is also suggested that the new cementing material-sand ratio could be further optimized.