Electrochemical characterizations and galvanic effect of chalcopyrite leaching and passivation-A review

Abstract

Chalcopyrite is the most important and abundant raw material for copper extraction in which hydrometallurgical leaching is more attractive. However, the leaching rate is limited, which is related to the properties of chalcopyrite and the passive film produced during leaching. Usually, the leaching of chalcopyrite is considered several electrochemical reactions whose redox processes, properties of passive film and substrate, mechanisms, and kinetics can be analysed by electrochemical characterizations (such as impedance plots (including Mott-Schottky curve and EIS plot), redox/open-circuit potential, potentiodynamic curves (including polarization curve and CV/LSV plot), and I-t/E-t curve) which are of easy manipulation, high efficiency, accuracy and credibility, and low cost and requirement. By initially introducing the properties of chalcopyrite and passive film, this paper reviews these recent electrochemical characterizations of chalcopyrite leaching and passivation, and the important electrochemical phenomenon-galvanic effect. The mechanisms of enhanced leaching, including manipulating lattice composition and structure, destroying p-n junction, regulating/attacking/hydrophilizing film, strengthening synergies, activating species/promoting diffusion, stabilizing cupric species by coordination, as well as improving adsorption, solid–liquid/intergranular electron transfer and galvanic effect, are also circumstantially discussed. To obtain more information about leaching and passivation, the joint use of several electrochemical characterizations is encouraged because of their different (dis)advantages. Finally, the prospect of chalcopyrite slurry electrolysis which integrates electrochemical leaching, ions purification and electrodeposition these three steps is envisaged.