Selective flotation separation of molybdenite and chalcopyrite by thermal pretreatment under air atmosphere

Abstract The flotation separation of molybdenite and chalcopyrite is very difficultly due to their excellent natural floatability. Thermally pretreat minerals under 250 °C before flotation was investigated as a potential approach for the flotation separation of molybdenite and chalcopyrite. The bench-scale flotation tests of single mineral were carried out and showed that chalcopyrite lost its floatability in flotation process. Whereas for molybdenite, it maintained good floatability. Based on the thermal pretreatment method, the flotation separation of molybdenite and chalcopyrite was realized for both mixed binary minerals and Cu-Mo bulk concentrates without addition of depressant. The XPS analysis results showed that the oxidation degree of chalcopyrite was much higher than that of molybdenite. For chalcopyrite, the oxidation products were hydrophilic species, which made it cannot be recovered in the flotation process. For molybdenite, despite slight surface oxidation, the little changes of surface S species made it still can be easily recovered in the flotation process. According to these findings, the thermal treatment method can be potentially applied as an effective route to separate Cu-Mo sulfide ore.