Copper and gold recovery from CPU sockets by one-step slurry electrolysis

Abstract

Recently, the life span of electric and electronic products is becoming shorter and shorter because of the rapid technology innovation and the rising standard of consuming. This also leads to a stable annual increase of waste electric and electronic equipment (WEEE). Waste printed circuit boards, the base of almost all WEEE, are always the core of WEEE recycling. However, few studies are focused on the recovery of WPCBs electronic components. Here, in this study, CPU sockets were chosen as a representative electronic component to explore if slurry electrolysis can directly and simultaneously recycle copper and gold. Four factors, HCl concentration, pulp density, current density and reaction time, were discussed in detail. The results show that copper recovery rate first increases and decreases with the rise of HCl concentration, pulp density and reaction time, and it increases with the increase current density. Copper recovery rate and purity is up to 96.67% and 98.16% respectively at the optimum conditions (4 mol/L HCl, 75 g/L pulp density, 80 mA/cm2 and 4 h). One third of copper can be electrodeposited to the cathode plate, and be collected directly. 67% copper still exit in the electrolyte, which needs to be further recycled, and less than 1% copper are in the anode residue. Gold recovery rate first increases and then decreases with the rise of the four factors, reaching to the highest value of 95.73% (4 mol/L HCl, 100 g/L pulp density, 70 mA/cm2 current density and 4 h). Gold mainly exits in the electrolyte, and little gold can be electrodeposited. Besides, the results of XRD and SEM show that the obtained metal powder is mainly copper and copper powder particles are mainly dendritic. On the basis of these results, slurry electrolysis could be applied to the recovery of copper and gold from electronic component.