The Use of Magnesium Thiosulfate Solution to Leach Gold from Disposed Cell Phones

This study investigated the leaching of gold from discarded cell phone printed circuit boards (PCBs) using magnesium thiosulfate solution as a safer alternative to cyanide. The objectives included analyzing and pre-concentrating the pulverized PCBs, optimizing leaching efficiency, and electrowinning the extracted gold. The PCBs were pulverized and analyzed using energy dispersive spectroscopy (SEM/EDX) to confirm the gold content. Magnetic separation was used to remove ferrous components, followed by treatment with trioxonitrate (V) and hydrogen tetraoxosulfate (VI) acids to eliminate base metals like copper and zinc. The residue was then leached with the thiosulfate solution with various concentrations of copper (II) sulfate and ammonia added to enhance gold dissolution. The leachate was used for electrowinning, and the gold content was analyzed with SEM/EDX. The result showed maximum gold dissolution of 0.70 ppm. EDX analysis confirmed the presence of gold in the electrowinning deposit. The study concludes that gold can be extracted from electronic waste using this method, offering a viable alternative for precious metal recovery and improving electronic waste management.