Effect of cuprous ions on Cu leaching in the recycling of waste PCBs, using electro-generated chlorine in hydrochloric acid solution

In the present study, the leaching of copper using electro-generated chlorine in hydrochloric acid solution has been carried out. The behavior of cuprous ions during the electro-leaching of copper has been extensively investigated. During the leaching of copper with the electro-generated chlorine, the copper leached out as cuprous ions which were accumulated in the solution and affected the oxidation–reduction potential of the leaching solution. The increasing rate of cuprous concentration linearly decreased with current density, which was verified by the retardation of the oxidation–reduction potential drop. At a current density 400 A m−2, the leaching rate of copper increased linearly with increase in stirring speed and became saturated at stirring speeds of more than 600 rpm. When the supplement of cuprous ions to the anode was rapid enough to consume the applied charge, the anodic reaction changed from chlorine generation to cuprous oxidation. The change of the anodic reaction retarded the leaching of copper. Therefore, the cuprous ions generated from copper leaching simultaneously affected the leaching of copper and the anodic reaction.