Leaching and electrochemical recovery of copper, lead and tin from scrap printed circuit boards

The recovery of copper, lead and tin from scrap printed circuit boards (PCBs) has been achieved using a combination of leaching, electrochemical ion exchange and electrodeposition. A simple aqueous nitric acid stripping solution, with the concentration range of 1-6 mol dm(-3), has demonstrated the potential for selective extraction of copper and lead from the PCBs. Precipitation of tin as H2SnO3 (metastannic acid) occurred at acid concentrations above 4 mol dm(-3). Preliminary galvanostatic electrolysis from simulated leaching solutions has investigated the feasibility of electrodeposition of copper and lead at different concentrations of HNO3. Cathodic lead deposition, particularly at high electrolyte conditions, resulted in poor current efficiency. This was mainly due to dentritic metal formation and subsequent re-dissolution. An alternative method investigated for recovering the metal values was the simultaneous electrodeposition of copper at the cathode and lead dioxide at the anode. Electrohydrolysis for acid and base regeneration from the spent nitric acid electrolyte has also been investigated. (C) 2002 Society of Chemical Industry.