Scale Up of a Process for Extraction of Tin, Lead, and Copper from Waste Printed Circuit Boards by Simultaneous Electrowinning

This paper focuses on recovering tin, lead, and copper (Sn, Pb, Cu) from low-grade printed circuit boards (PCBs). The metals are recovered by series of dissolution, filtration, and electrowinning steps. During electrowinning, copper is recovered as Cu sheets at the cathode, and Pb is recovered as lead dioxide (PbO2) at the anode. Process intensification is achieved through the simultaneous recovery of these two metals in a single electrowinning step. The unreacted nitrate salts along with nitric acid from the electrowinning step is recycled back for dissolution making the process sustainable. Dissolution experiments with PCBs helped determine the concentration of Cu and Pb that can be expected in the feed solution of the electrowinning step. Electrowinning experiments were performed with synthetic solutions at these concentrations to determine the optimum conditions. Electrowinning experiments with PCB leachate were carried out to determine interference effects of other metals. To establish the robustness and scalability, multi-cell experiments were performed using synthetic and PCB solutions. The results of these experiments were used to establish mass balance for the process with recycle streams to treat 100 kg of PCBs per batch. The proposed mass balance is based on data collected from experiments for each of the steps.