Recovery of precious metals from PCBs of e-waste

Abstract

In international market, the price of precious metals is increasing rapidly due to increase in its demand. Limited natural resources, stringent environmental regulations and generation of huge amount of e-waste containing precious metals (Au, Ag, Pd, Pt) compels to develop feasible technology to recover metals from waste and save the environment from other hazardous substances present in such wastes. Present paper is focused on the recycling of precious metals (Au, Pd) from the printed circuit boards (PCBs) of e-waste. PCBs were de-soldered to separate the integrated circuits (ICs) and separated ICs were pulverized to get fine powder. The pulverized ICs were analysed and found to contain ~0.8% Au, 0.01% Pd, 12% Cu along with plastics and ceramics. Leaching was carried out using nitric acid to dissolve Cu and Pd, leaving Au in the leached residue. Solvent extraction studies were carried out using 0.5% LIX84IC at low pH to selectively extract Pd leaving Cu in the raffinate. Further, using cementation/ evaporation techniques, metal / salt of Cu and Pd were produced. The process developed is environment friendly and acts in accordancewith stringent environmental policy.