Bureau of Mines research showed that galvanic interactions between grinding media and chalcopyrite influence the self-induced floatability of chalcopyrite in simulated process water. Similar results were obtained with a synthetic chalcopyrite-quartz mixture and a natural ore, and floatability was dependent on the electrochemical conditions in grinding, conditioning, and flotation stages. High-carbon and stainless steel media were investigated, as well as the absence or presence of air during grinding, conditioning, and flotation. For grinding with high-carbon steel in the absence of air, low grinding-solution ph was detrimental to chalcopyrite recovery at constant flotation ph. As grinding- solution ph was increased, chalcopyrite floatability increased as a result of lower galvanic interactions during grinding in higher ph solution. High-carbon steel was passivated at higher ph. In the presence of air, chalcopyrite flotation was not significantly affected by grinding-solution ph. Stainless steel was more easily passivated than high-carbon steel, and chalcopyrite floatability was significantly higher after air or n2-purged grinding with stainless steel media. Chalcopyrite floatability increased with increasing flotation pulp potential. For given grinding conditions, flotation with air gave higher chalcopyrite recovery than flotation with n2. For the natural ore, chalcopyrite was depressed while molybdenite was floated with n2, and chalcopyrite was subsequently recovered by flotation with air.
Preprints, 2nd Workshop on Flotation of Sulphide Minerals, Lulea, Sweden, 6/18-21/90, PP. 5-19