Galvanic interactions between grinding media and chalcopyrite influence the self-induced floatability of chalcopyrite in simulated process water. Rest potential, combination potential, and polarization measurements were used to characterize these interactions. For both a synthetic chalcopyrite-quartz mixture and a natural ore, floatability was dependent on the electrochemical conditions during grinding, conditioning, and flotation stages. Nitrogen-purged and open-to-air atmospheres were investigated for chalcopyrite ground with high-carbon and stainless steel media. For grinding with high-carbon steel in a n2-purged atmosphere, chalcopyrite recovery increased with increasing ph, at constant flotation ph, because of lower galvanic interaction during grinding in the higher ph solution. Grinding solution ph had little effect when the mineral was ground with high-carbon steel in air, as confirmed by electrochemical polarization measurements. Electrochemical measurements showed that high-carbon steel was passivated at higher 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. Increased chalcopyrite floatability was observed with more positive flotation pulp potentials. For given grinding conditions, the type of flotation gas has a strong effect on recovery. For example, for natural ore, chalcopyrite was depressed while molybdenite was floated with n2, and chalcopyrite was subsequently recovered by flotation with air.