Selective Removal of Copper from Nickel–Copper Leach Solution by Electrolysis Cells with High Convection

In this study, the selective separation of copper ions (Cu2+) from leaching solutions containing both Cu2+ and nickel ions (Ni2+) was investigated using electrolysis cells with high convection (Chemelec). Firstly, the electrochemical behavior of solutions containing only single Cu2+, single Ni2+, and both Cu2+ and Ni2+ was investigated using cyclic voltammetry (CV). Cu2+ reduction was observed at −0.15 V in solutions that contained either simply Cu2+ or a Cu2+-Ni2+ combination, whereas oxidation happened at 0.17 V in a single step. The CV analysis of a Ni2+-containing solution at pH 1 revealed that Ni2+ was not reduced. Potentiostatic selective Cu2+ reduction experiments were conducted at cathode potentials of −0.3 V, −0.4 V, and −0.5 V. Increasing the potential from −0.3 V to −0.5 V enhanced copper recovery from 84% to 94%. The current efficiency remained above 90% across all three potentials during 3 h experiments. At −0.5 V, extending the experiment time from 3 h to 5 h resulted in copper recovery exceeding 99%, while current efficiency declined from 90% to 80%. The cathode products were analyzed using X-ray diffraction (XRD), revealing that the main phase consisted of metallic copper.