Recovery of Precious Metals from Discarded Mobile Phones by Thiourea Leaching

The objective of this work was to recover gold and silver from the printed circuit board (PCB) of discarded mobile phones by thiourea leaching. Effects of thiourea concentration, leaching temperature, leaching time, and ferric ion (Fe 3+ ) concentration on the recovery of gold and silver were investigated. The PCB was pretreated physically to reduce the thiourea consumption and enhance the leaching process. It was found that the percentage of gold leaching was higher than that of silver at different conditions studied. The highest percentages of gold (96%) and silver (90%) leachings were achieved with 20 g/L of thiourea and 8 vol% of Fe 3+ at 4 h of leaching time and 25°C of leaching temperature.