Abstract: Chalcopyrite and molybdenite ores often co-exist in nature, which are usually separated by flotation. However, the current flotation separation methods may cause heavy environmental pollution issues. In order to explore a clean and efficient separation method for copper-molybdenum sulfide ore separation, pure and artificially mixed chalcopyrite and molybdenite samples were pretreated with H₂O₂ as oxidant in sea water or pure water. The influencing mechanism was revealed by contact angle measurement and XPS analysis. The results showed that: ①In sea water or pure water, the floatability of chalcopyrite after H₂O₂ treatment was significantly reduced. Differently, pretreatment with H₂O₂ could improve the flotability of molybdenite in sea water but reduce the flotability in pure water. ②After pretreatment with H₂O₂, the flotability of chalcopyrite was reduced due to the surface oxidation by H₂O₂ with the formation of hydrophilic oxidation. The effect of H2O2 on the flotability of molybdenite was relatively weak in pure water or sea water, possibly due to the weak oxidation of H2O2 on molybdenite surface. ③The samples artificially mixed with chalcopyrite and molybdenite pretreated by H₂O₂ could be separated effectively in either pure water or sea water, with a better separation efficiency being observed in sea water. The study provides guidance for chalcopyrite and molybdenite flotation using sea water replacing pure water.

Key words: Chalcopyrite, Molybdenite, Flotation separation of Cu and Mo, H₂O₂, Sea water