Effect of added cobalt ion on copper electrowinning from sulfate bath
using doped polyaniline and Pb-Ag anodes
(1. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology,
Kunming 650093, China;
2. The No. 705 Research Institute, Kunming 650118, China)
Kunming 650093, China;
2. The No. 705 Research Institute, Kunming 650118, China)
Abstract: Effect of added Co2+(aq) on copper electrowinning was studied using doped polyaniline (Pani) and Pb-Ag(1%) anodes and a stainless steel cathode. The presence of added Co2+(aq) in the electrolyte solution was found to decrease the anode potentials. The optimum level of Co2+(aq) concentration in the electrolyte, with respect to the maximum saving of power consumption was established. Linear sweep voltammetry (LSV) was used to study the influence of added Co2+(aq) on the anodic processes in a copper sulfate-sulfuric acid electrolyte. The oxygen-evolution potential for Pani anode is depolarised at lower current densities (≤0.01 A/cm2) and attains saturation at ρ(Co2+)o≈0.789 g/L; whilst the oxygen-evolution potential for Pb-Ag(1%) anode is depolarised at higher current densities (≤0.02 A/cm2) and attains saturation at ρ(Co2+)o≈1.315 g/L. The preferred orientations of the copper deposits change from (220) to (111) with the addition of 0.394−0.789 g/L Co2+ but higher concentrations favor (220) orientation again.
Key words: copper electrowinning; cobalt additive; electrode potentials; polarisation