Sustainable electrochemical recovery of high-purity Cu powders from multi-metal acid solution by a centrifuge electrode

The green recovery of high value-added Cu products from electroplating sludge is an urgent challenge to the harmless disposal and sustainable utilization of hazardous waste. Hydrometallurgy based on leaching and electrodeposition is an environment-friendly process. A low-concentration and multi-metal solution is usually obtained after leaching. Generally, crude Cu products are only produced by electrodeposition. In this paper, a centrifuge electrode is proposed for the simple and green recovery of high-purity Cu powders by one-step electrodeposition from leaching solution of electroplating sludge. The current density of Cu electrodeposition can be enhanced based on the results of cyclic voltammetry. It is confirmed that the purity, recovery ratio and current efficiency of Cu products are obviously increased by the centrifuge electrode due to the enhanced mass transfer. The electrodeposition of metal impurities is effectively inhibited. The structure of Cu products is adjusted from foils to powders by the combination of Cu concentration and rotating speed. Particularly, high-purity Cu powders are electrodeposited on the centrifuge electrode from Cu-Ni mixed solution with 2 g L−1 Cu2+ and 2 g L−1 Ni2+. In addition, the purity, recovery ratio, current efficiency and particle size of Cu powders depend on H2SO4 concentration and current density. Cu powders with a purity of 99.9% are selectively separated from the multi-metal leaching solution of electroplating sludge.