Gold recovery from printed circuit boards of mobile phones scraps using a leaching solution alternative to cyanide

Abstract

Currently, the printed circuit boards (PCB) of waste electrical and electronic equipment (WEEE) are attracting interest among researchers for environmental concern reasons and mainly for their content of precious metals such as gold. Thus, this study aims to characterize different types of PCBs from mobile phones in relation to the amount of gold contained, to evaluate alternative leaching agents for the gold (ammonium and sodium thiosulfate) and compare these to commercial stripping (cyanide-based) and then the recovery of gold by the electrometallurgical route. First, the amount of gold was determined. Then, alternative leaching agents were tested under different concentrations and time. A cyanide-based solution was also tested to compare the results. The results showed that the content of gold varied from 142 to 700 g/ton. The cyanide-based solution was able to extract 88% of the gold, while sodium and ammonium thiosulfate extracted 70 and 75% of the gold, respectively. The electrowinning tests showed a 94% recovery of the gold present in thiosulfate solutions.