Improving flotation recovery of copper sulphides by nitrogen gas and sulphidisation conditioning

This paper describes investigations to increase the flotation recovery of copper from ores containing both primary and secondary copper minerals. An increase in the flotation recovery of copper is obtained by conducting controlled potential sulphidisation conditioning in the absence of dissolved oxygen. Sulphidising reagents have been widely employed for the flotation of secondary copper minerals and in the case of molybdenum production the flotation depression of copper sulphides. However, by using nitrogen gas to exclude oxygen and by careful control of the sulphidisation process it has been possible to increase the flotation recovery of chalcocite, chalcopyrite and bornite. The additional recovery is believed to be from particles with oxidised or tarnished surfaces where surface oxidation has been reversed. The use of nitrogen to exclude oxygen increases the efficacy of new sulphide surface formation and improves process efficiencies by maximising the availability of sulphide ions for surface sulphidisation to occur at the lowest sulphide consumption levels.