The Active-to-passive Transition of Chalcopyrite

The active-to-passive transition of chalcopyrite is studied using electrochemical techniques and leaching tests to establish the conditions under which chalcopyrite electrodes display active-passive behavior. Results from potentiostatic anodic polarizations are predictive and agree very well with leaching results while potentiodynamic techniques give only erratic values. The critical current and oxidation rate in the active potential range increases with the concentration of acid, but the passivation potential decreases. The corrosion rate of chalcopyrite was studied at various temperatures and concentrations of acid in electrolytes containing only ferric (no ferrous) using electrochemical impedance spectroscopy; the higher the concentration of acid and the lower the temperature, the lower the corrosion rate.