Improving the flotation behavior of a sulfide ore by controlling electrochemical interactions during grinding

The effect of grinding media and purging gas during grinding, on the flotation behaviour of a complex copper-lead-zinc sulphide ore was investigated. The optimum recoveries and grades of chalcopyrite were obtained with 21 % chromium medium combined with nitrogen purging. Mild steel medium may depress chalcopyrite flotation due to a high amount of oxidized iron species in the mill discharge. Grinding media displayed an influence on the Eh and galvanic current between media and mineral electrodes. The more electrochemically active the grinding media and the more oxidizing the environment, the greater the amount of oxidised iron in the slurry. Mild steel and high chromium media are more electrochemically active than the examined sulphide minerals. A generic approach to optimizing grinding conditions to improve the flotation separation of sulphide minerals is suggested by the study. Copyright The Electrochemical Society.Stephen Grano and Guozhi Huan