Potential‐Selective Deposition of Copper from Chloride Solutions Containing Iron

The hydrometallurgy of copper may involve leaching of the metal from its ore with an aqueous solution containing cupric and ferric chloride. The subsequent deposition of copper from such a process stream is modeled here in an idealized electrochemical cell with a rotating-disk electrode. The potential distribution and concentration profiles within the diffusion layer are predicted for given potential differences between the electrode and the solution. The cuprous ion, which is formed by the reduction of the complexed cupric ion at the electrode, is stabilized in the chloride solution and can react either at the electrode or with ferric species within the diffusion layer. The assumption is that this fast and irreversible homogeneous reaction generates a reaction plane, whose position is shown in the concentration and potential profiles. In addition, the position of the reaction plane is plotted as a function of the potential difference between the electrode and the adjacent solution. Predicted current-potential and current efficiency-potential curves are also reported. Finally, the iron contamination of the deposited copper is estimated to be less than 10-5 atom percent for some cases. Also, because some of the partial current densities are below their limiting values, the analysis is strictly valid only at the center of the disk. © 1977, The Electrochemical Society, Inc. All rights reserved.