Chemical mapping and analysis of electronic components from waste PCB with focus on metal recovery

This paper describes a detailed chemical characterization of connector pins separated from diverse electronic components removed from waste printed circuit boards (WPCB) of computers. Chemical maps by SEM-EDS (Scanning Electron Microscopy - Energy Dispersive Spectroscopy) indicated that the substrates of all connector pins are made by Cu-Sn, Cu-Zn or Cu-Sn-Zn alloys, which are covered by thin Ni and Au layers. The ICP-OES (Inductively Coupled Plasma- Optical Emission Spectrometry) analysis of the different connector pins revealed that these materials are mostly constituted by Cu (62-88% w/w) and very attractive Au contents were found (up to 1273 git). For all pins, intermediate contents of Zn, low contents of Ni, Sn and Pb and very low contents of Pd and Fe were determined. A heterogeneous, 100% metallic sample was prepared by mixing all individual connector pins aiming at contribute to the development of feasible technologies for recovering valuable metals. The mixed sample contains about 73% w/w Cu and 168 git Au, which are higher than the contents reported in the literature for samples obtained after grinding assembled or disassembled WPCB. The leaching of the mixed sample without grinding and concentration steps will reduce operating costs and maximize metals recovery avoiding mass losses. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.