To better understand the role of chalcopyrite dissolution in improving Cu extraction in hydrometallurgical processing, the effect of redox potential (E_h), acid type, pH, temperature and the addition of Fe~(2+) have been investigated to determine the kinetics of reaction and to optimise the leach conditions. The redox potential was found to have a positive effect on leach rate up to 750 mV (SHE), above which no significant improvement was observed. There was no apparent difference in the Cu leach rate in pH 1.0 HCIO_4 compared to H_2SO_4; however, these Cu release rates were distinctly greater than that in pH 1.0 HCl. An increased Cu leaching rate was observed at increased temperature; the positive effect of added Fe~(2+) decreased with increasing temperature. Elemental sulfur (S~0) has been confirmed as the predominant crystalline product by XRD, which also indicated the formation of goethite at pH values over 1.0. Relative surface area normalised leach rate analyses, SEM and ToF-SIMS measurements suggest that the surface products of S~0 and/or goethite at a redox potential greater than 700 mV(SHE) did not inhibit chalcopyrite leaching.
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