Electrochemical study of leached chalcopyrite using solid paraffin-based carbon paste electrodes

An experimental study was conducted to investigate the pyrite-assisted leaching of chalcopyrite concentrate in iron sulfate media. It is shown that the catalytic effect of pyrite is variable depending on the source of the sample. Electron micrographs and EDX spectra are presented showing the chalcopyrite surface covered with sulfur of different morphologies after leaching in the absence and presence of two different pyrite samples. It is shown that the ability of chalcopyrite to reduce ferric declines with time spent in the leaching reactor. A systematic electrochemical study of chalcopyrite in 0.5 M sulfuric acid solution using solid paraffin-based carbon paste electrodes (SPCPE) was also undertaken. A comparative study of the electrochemical response of chalcopyrite electrodes before and after leaching in the absence and presence of pyrite for various periods up to 45 h was conducted using cyclic voltammetry. It is concluded that pyrite has a higher electrocatalytic activity for the ferric reduction reaction than chalcopyrite. The results also show that as the leaching process progresses, the anodic and cathodic current densities in the voltammograms decrease, as expected. Current densities measured on electrodes of chalcopyrite made from samples leached in the presence of pyrite were lower by several orders of magnitude compared to samples leached in the absence of pyrite. (C) 2011 Elsevier B.V. All rights reserved.