Flotation separation of chalcopyrite and molybdenite by externally controlled potential method

Chalcopyrite-molybdenite separation has always been a major difficulty in mineral processing. At present, chemical agents are commonly used to regulate the pulp potential. However, the air flowing into the flotation process easily destroys the reducing atmosphere, resulting in the increase in reagent dosage. Externally controlled potential flotation can reduce the consumption of reagents by adding electrodes to the pulp to control the pulp potential. The effects of mineral size, pulp pH, and externally controlled potentials on the flotation behavior of chalcopyrite and molybdenite were investigated in the present work using a self-made externally controlled potential flotation cell. Under the optimal conditions, the separation test of Cu-Mo concentrate was conducted using the externally controlled potential flotation. The results were verified by cyclic voltammetry and galvanic corrosion tests. The results show that chalcopyrite with -150+31 μm fraction is considerably affected by externally controlled potentials and is easily inhibited, whereas molybdenite with -150+31 μm fraction is not easily inhibited. Chalcopyrite and molybdenite with -31 μm fraction have poor floatability and are less affected by externally controlled potentials. Externally controlled potential flotation is conducted under alkaline conditions to facilitate the inhibition of chalcopyrite and the flotation of molybdenite. In the case of pH 11, the optimal externally controlled potential for chalcopyrite-molybdenite separation is -1100 to -700 mV (vs Ag/AgCl). Under the conditions of pH 11 and externally controlled potential of -800 mV (vs Ag/AgCl), the Duobaoshan chalcopyrite-molybdenite mixed concentrate was separated by flotation. After one flotation cycle, the primary molybdenum concentrate with 80.57% recovery of molybdenum and 10.19% recovery of copper can be obtained. The flotation difference between molybdenite and chalcopyrite reaches 70.38%, which makes it possible to separate chalcopyrite and molybdenite by externally controlled reduction potential. In addition, galvanic corrosion between chalcopyrite and molybdenite promoted the flotation of molybdenite and the inhibition of chalcopyrite.