Hydrometallurgical processing of waste integrated circuits (ICs) to recover Ag and generate mix concentrate of Au, Pd and Pt

Abstract

Present research reports a novel and feasible process to recover Ag and generate concentrate of precious metals (Au, Pd and Pt) from waste ICs present in PCBs of computers. Initially, depopulated ICs were pulverized and beneficiated to obtain metallic concentrate, which contained (per ton) 7 Kg Ag, 5 Kg Au, 110 g Pd and 4 g Pt along with Cu, Pb, Fe and Ni. Leaching was carried out and found that at optimized condition i.e. 3 M HNO3, temperature 80 C, pulp density 50 g/L and mixing time 1 h, >90% of Ag, Cu, Pb and Ni were leached leaving Au, Pt and Pd in the residue. From the leach liquor, Ag was precipitated using 1 M KCl in 30 min and other metals were recovered by precipitation, solvent extraction and cementation methods. All wastes (solid/ liquid) generated during process development could be treated using standard environmental procedure.