Flotation-assisted electrodeposition process to recover copper from waste printed circuit boards
Yamin Li, Xuehao Wei, Hongjun Liu, Yan Sun
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 %.