In Situ Electrochemical Investigation of Pyrite Assisted Leaching of Chalcopyrite

Chalcopyrite is not only the most abundant but also one of the most refractory sources of copper. In this study, leaching experiments showed that leaching efficiency increases with increasing amounts of pyrite. In the absence of the addition of pyrite, chalcopyrite was leached at an approximate rate of 0.03 g/L/day. This rate increased to approximately 0.29 g/L/day when the pyrite/chalcopyrite (Py/Cp) weight ratio was 5. Polarization curves show that the i(couple)/i(corr) value was 1.71 at a cathode to anode (S-c/S-a) area ratio of 1:1. Galvanic corrosion tests of current confirmed that the chalcopyrite leaching selectivity improved with an increasing Py/Cp ratio. Electrochemical impedance spectroscopy (EIS) results showed that the chalcopyrite electrochemical dissolution (leaching) rate depended on the charge transfer at the double layer and the passive film characteristics and that the chalcopyrite corrosion rate decreased as soak time increased. The presence of pyrite promotes the electrochemical dissolution of chalcopyrite and results in galvanic protection. (C) The Author(s) 2018. Published by ECS