A green and economical process for resource recovery from precious metals enriched residue of copper anode slime

Abstract

The precious metals enriched residue of copper anode slime (PM-CAS) obtained from our previous study, creates favorable conditions for recycling resource. In this study, a green and economical process for resource recovery from PM-CAS is proposed. Results showed that 99.70% Ag and 98.65% Pd were successfully leached in 10 min by HNO3-citric acid under optimized conditions with 99.81% Au retained in the residue. The reason could be the boosting effects came from the phase transition of PM-CAS and the enhanced leaching driving force by coupling HNO3 and citric acid. It was found that NaCl precipitation with glucose reduction could recover 99.99% Ag with a purity of 99.99% from the leachate under preferred conditions. Meanwhile, 99.90% Pd could be easily recovered from the Ag-separated solution by the previously recycled Cu powder (RCu). In addition, 98.16% Au was recovered from the Au-retained residue by 1.0 mol/L HCl and 8.0 g/L KClO3 leaching and RCu reduction. Comparably, the process could achieve the total recovery efficiencies of 99.69% Ag, 98.55% Pd, and 97.97% Au with cheaper and lower concentration reagents and RCu, which was promising to obtain a net profit of about $250,857/ton of PM-CAS. Therefore, the proposed process could be a potential choice for green and economical resource recovery from PM-CAS.