Flotation-assisted electrodeposition process to recover copper from waste printed circuit boards

Abstract

Electrodeposition is an attractive method to recover copper from waste printed circuit boards (WPCBs), which preferably requires metal-rich concentrate as raw material. In this study, a metal-rich route for WPCBs was established to assist copper electrodeposition by using flotation method. Different from aqueous disperse medium in conventional flotation, we proposed ethanol as a disperse medium to improve dispersivity and sustainability. An H-type electrolytic cell with a cation exchange membrane was used to electrolyze copper in metal-rich concentrate at the anode and recover pure copper on the cathode. The experiments were conducted to investigate the effect of grade on the proportion of metal-rich concentrate after flotation and the electrodeposition rate of copper, and the key factors (solid-to-liquid ratio and applied voltage) affecting copper electrodeposition were evaluated. The results show that the flotation with ethanol can greatly enrich copper, and the copper content in metal-rich concentrate can be increased by 182.3 %, with a copper recovery rate of 85.1 %. Increasing the solid-to-liquid ratio and applied voltage can increase the deposition rate of copper, but affects the stability of electrodeposition. The optimized electrodeposition parameters are: electrolyte temperature of 50℃, solid-to-liquid ratio of 25 g/L, and applied voltage of 10 V. The purity of copper in electrodeposits can reach over 99 %.