Electrochemical characterization of chemical species formed during the electrochemical treatment of chalcopyrite in sulfuric acid Article uri icon

abstract

  • The dissolution mechanism of chalcopyrite, and the potential range in which its passivation phenomenon takes place, were studied on carbon paste electrodes with chalcopyrite (99.46%25 purity, %2b300 mesh, 53 μm size) (CPE-CP) in 1.7 mol/dm3 H2SO4. A sequence of anodic potential pulses was applied to the CPE-CP to characterize its electrochemical behavior. Copper ions, dissolved by the potential pulses, were determined using a mercury film electrode (MFE) and the anodic stripping voltammetry (ASV) on a vitreous carbon disk. In addition, the modified surface of CPE-CP was characterized, before and after the potential pulses, by cyclic voltammetry (CV). The characterization of the final surface state of each electrochemically modified CPE-CP and the amount of dissolved copper showed five potential regions where the chalcopyrite dissolution mechanism changed. The initial dissolution occurs at 0.615 V ≤ Eanod < 1.015 V versus SHE forming a non-stoichiometric polysulfide (Cu1-rFe1-sS2-t). The absence of copper ions in the solution indicates a passive sulfide. However, at 1.015 V ≤ Eanod < 1.085 V versus SHE, the passive product decomposes forming porous layers of non-stoichiometric polysulfide (Cu1-xFe1-yS2-z) that allow the diffusional transport of charged species and the dissolution of the mineral. In the region of 1.085 V ≤ Eanod < 1.165 V versus SHE, formation covellite (CuS) was identified. At E > 1.165 V versus SHE, CuS is unstable and gives rise to complete dissolution of the chalcopyrite. Due to the experimental conditions, the mineral dissolution is inhibited by possible jarosite precipitation. © 2006 Elsevier Ltd. All rights reserved.

publication date

  • 2006-01-01