Abstract: The types and amount of admixtures for preparing filling materials were optimized through single factor test and orthogonal test in process of preparing cemented materials by unclassified flotation tailings of sulfide for underground filling. The optimal preparing conditions were obtained as the ratio of cement to tailings ratio 0.25, water to cement 0.4, cement, gypsum and lime ratio of 6∶3∶1, dosage of MNC-A1 2.5%, sodium silicate 140g/t, and filling material concentration 70%. Under these conditions, the compressive strength of filling materials reached 1.668 MPa in three days, which meet the compressive strength (>1MPa) of filling material used underground filling.

Key words: Unclassified tailings, Cemented filling, Cemented materials, Orthogonal test