Developments in Selective Flotation of Complex Copper-Lead-Zinc

Sulphur dioxide has been successfully used as a depressant for galena and sphalerite in selective copper flotation of complex fine-grained sulphide ores. Dosage of the gas demands care and that is why it is not used as often as it could be. The sulphur dioxide gas has been replaced by a solution of sulphur dioxide forming salt with improved selectivity. Easy dosage of the reagent and use of selective copper mineral collectors has demonstrated better process control with upgraded products. On an Australian Cu-Pb-Zn ore the key to improved process was the finding that gangue minerals of the ore have buffer capacity to allow the stagewise addition of acidic reagent solution and still maintain the narrow pH range of selective separation of chalcopyrite and galena even with simple manual process control.

On a Russian Cu-Pb-Zn ore good selectivity against galena and sphalerite was obtained in the flotation of bornite and chalcopyrite as a high grade copper concentrate. Stagewise grinding-flotation with three grinding steps were used to obtain reasonable liberation of copper minerals and to maintain the optimum selectivity.