The dissolution of chalcopyrite in chloride solutions Part 2: Effect of various parameters on the rate

In Part 1 of this series, which describes the results of a study of the dissolution of chalcopyrite under conditions that could be expected in a heap leaching process for primary copper minerals, it was shown that enhanced leaching of chalcopyrite from several copper concentrates in dilute acidic chloride solutions can be achieved by controlling the potential in a range of 560-600 mV (SHE) in the presence of dissolved oxygen. Based on the results of these experiments, this paper reports on an extensive study of the kinetics of the dissolution of several chalcopyrite concentrates in chloride solutions under various conditions in especially designed reactors. It will be demonstrated that the rates of dissolution at constant potential in the range of 580-600 mV by control of the oxygen supplied to the reactor are approximately constant for up to 80% dissolution for sized fractions of the concentrates. The rate of dissolution of chalcopyrite under these conditions is largely independent of the pulp density, iron and copper ion concentrations which could be expected in a heap leach operation, the acidity and the chloride ion concentration. Variation of the temperature in the range 25 to 75 degrees C under otherwise constant conditions resulted in an activation energy for dissolution of two different concentrates of 72 kJ mol(-1). (C) 2010 Elsevier B.V. All rights reserved.