Synergistic Effects of Environmentally Friendly Collectors in the Preconcentration Step of a Double Float Process on Sedimentary Phosphate Ore

Sedimentary phosphate rock is a precious source for phosphoric acid and fertilizers like NPK. During beneficiation of the ore, typically flotation is used for purification of the ore from gangue material like carbonates and silicates. A double float process using direct flotation with anionic collectors in the first stage and reverse flotation with cationic collectors in the second stage serves this purpose well. Carbonates, like dolomite or calcite and silicates are removed from the ore. This study focuses on collectors for the direct flotation of a sedimentary phosphate ore as the first step of purification. The target was to increase the P2O5 recovery to >90% at a constant P2O5 grade while separating as much carbonate as possible. Several anionic collectors and combinations thereof were tested. The best results were achieved using an environmentally friendly collector blend which yielded P2O5 recoveries of up to 95% while lowering the MgO grade from 5.1 to 4.1%.