Green Process of Metal Recycling: Coprocessing Waste Printed Circuit Boards and Spent Tin Stripping Solution

Electronic waste (e-waste), including waste printed circuit boards (PCBs), has caused global concern owing to its potential environmental pollution and rich resource content. Previous studies have indicated that urban mining for metals recycling can decrease energy consumption and pollutants emission compared to the extraction of metals from natural minerals. During the production of PCBs, a large amount of spent tin stripping solution (TSS) is simultaneously generated, containing the significant amounts of metal ions and residue nitric acid. In this study, the coprocessing of waste PCBs and spent TSS at room temperature was proposed and investigated, with the aim of developing an environmentally sound process to address these problems. This coprocessing approach proved to be effective. 87% of the Sn-Pb solder, 30% of the Cu, 29% of the Fe, and 78% of the Zn was leached from waste PCBs with spent TSS after 2 h, at room temperature. Moreover, approximately 87% of the electronic components were dismantled from waste PCBs. About 99% of the Sn, Pb, Fe, Cu, and Zn were recovered from the leaching solutions by chemical precipitation. The proposed green process has substantial advantages over traditional recovery methods of heating waste PCBs, in terms of both material and energy efficiency.