Selective Gold Recovery with Electrochemically Assisted Aqueous Reduction

Abstract The recovery of valuable and rare metals from complex feeds has become increasingly important to realize more circular hydrometallurgical processes. Electrochemical methods are an attractive option as they typically do not require chemical addition; however, competing reactions may lead to low current efficiencies. Therefore, targeted methods like electrodeposition-redox replacement (EDRR) and more recently electrochemically assisted aqueous reduction (EAR) have been developed. This work studies for the first time the impact of oxidants (Cu, Fe), passive base metals (Ni, Zn, Al) and precious metals (Pd, Pt, Ag)—commonly found in hydrometallurgical process streams—on gold recovery through EAR. The study is carried out with synthetic solutions simulating chloride leachates, where the impact of each metal impurity is first studied individually and then from a combined solution. High oxidant concentrations are observed to be detrimental for process efficiency, but the electrochemical pulse parameters can be adjusted to compensate. Finally, electrochemical quartz crystal microbalance analysis and deposit characterization reveals high selectivity for gold recovery from a combined multimetal solution. Graphical Abstract