The Active-Passive Behavior of Chalcopyrite: Comparative Study Between Electrochemical and Leaching Responses

Abstract

The oxidative behavior of chalcopyrite in media was studied using both electrochemical techniques and leaching experiments. The results of the two methods demonstrate that chalcopyrite oxidation displays the classical active-passive behavior observed in passivating metals; values predicted electrochemically for the passivation potential are in excellent agreement with leaching experiments. This result substantially improves the knowledge of the anodic behavior of chalcopyrite, which has been reported so far mostly as pseudopassive when massive chalcopyrite electrodes are used. Imposing a continuous series of potentiostatic pulses (increasing by ), three-dimensional current density-time-potential surfaces were generated in order to establish the effects of acidity and temperature on the passivation potential, the passive current, and the critical current of chalcopyrite leaching. The concentration of sulfuric acid was systematically varied from and temperature from . increases with increasing temperature from at up to at ; it is practically insensitive to acidity at low and high temperatures. At an acid-dependent transition of was observed from . The passive currents were at most one order of magnitude lower than the maximum critical current.