Kinetics of chalcopyrite leaching in either ferric sulphate or cupric sulphate media in the presence of NaCl

The shrinking core model (SCM) has been extensively applied in the kinetics analysis of particulate systems. This is because in its classical form it is one of the simplest models developed for fluid-solid reactions. However, it requires single-sized solid grains failing to describe the leaching kinetics for broad particle size distributions (PSDs). The current investigation successfully applied an extension of the SCM to the leaching of chalcopyrite with a broad PSD in a mixed chloride-sulphate solution. Such a medium was selected because there is renewed attention to leaching in mixed systems due to the increasing utilization of saline waters in both leaching and bioleaching of sulphide ores. Moreover, chloride is a catalyst of chalcopyrite leaching. Specifically, the effects of temperature (70 degrees C to 90 degrees C) and reagent (Fe3+, Cu2+ and Cl-) concentrations on the leaching kinetics were determined. The results showed that chalcopyrite leaching was faster with Cu2+ (larger rate constant) than with Fe3+, but the activation energy was similar in both cases with 66.6 kJ/mol for 0.5 mol/L of Cu2+ and 66.8 kJ/mol with 1.0 mol/L Fe3+. (C) 2016 Elsevier B.V. All rights reserved.