Electrochemical recovery of copper, lead and tin from a nitrate and chloride leaching solution of scrap printed circuit boards

A study for recovering copper, lead and tin from scrap printed circuit boards (PCBs) has been carried out using a combination of leaching and electrodeposition. A simple aqueous nitric acid stripping solution has demonstrated the potential for selective extraction of copper and lead along with the precipitation of tin as H2SnO3 at acid concentration above 4 mol/dm(3). The electrodeposition of copper and lead in a nitrate environment has shown the influence of pH on the efficiency of the process. Alternatives that have been considered include the simultaneous electrodeposition of copper at the cathode and lead dioxide at the anode. The recovery of tin via electrodeposition from a chloride medium, obtained after dissolving the precipitate H2SnO3 in hydrochloric acid, was then studied. The use of a flow-through porous electrode (carbon felt) has been shown to be very efficient for the electro-recovery of metal ions when the concentration of species in solution becomes of the order of 100 ppm. The large specific surface area along with the turbulence generated by the electrolyte flow through the porous electrode considerably improves the mass transport to the electrode surface leading to a greater rate of electrolysis in comparison with a two dimensional electrode. The performance of a divided flow-through reactor is reported.