Technical and environmental assessment of gold recovery from secondary streams obtained in the processing of waste printed circuit boards

The current study focuses on the technical and environmental assessment of gold extraction from the solid residue obtained during the recovery of base metals from waste printed circuit boards (WPCBs). In the preliminary stage, the process involves the dissolution of gold using the H2O2-HCl leaching system followed by the electrowinning of a high purity gold deposit from the obtained leaching solution. The technical performance of the process was evaluated on the basis of the efficiency factor for the H2O2 and HCl usage, current and dissolution efficiency and specific energy consumption for gold electrowinning. The environmental impact assessment of the process was performed based on the mass balance data corresponding to the recovery of one kg of gold in the identified optimal operating conditions. The Biwer-Heinzle method was applied to determine the values of the General Effect Indices (GEI) for the input and output streams of the process. The GEI values were found to be quite small, close to the minimum possible, thus highlighting that the developed gold recovery process is not only efficient, but has an overall low environmental impact as well. (C) 2016 Elsevier B.V. All rights reserved.