Selective copper recovery from complex mixtures of end-of-life electronic products with ammonia-based solution

Electronic waste treatment within EU has focused on valuable metal recycling and has been defined by the EU directives. The difficulties for recycling are induced by the high complexity of such waste. In this research, a hydrometallurgical process was developed to recycle copper from industrially processed information and communication technology (ICT) waste. By using air as the oxidant and ammonia–ammonium carbonate leaching solution, copper could be extracted with high recovery – more than 90%, and high extraction selectivity – around 98%. In order to understand the copper extraction process and the reaction mechanisms, the effects of a range of parameters during copper leaching were comprehensively investigated, including ammonia concentration, leaching temperature, ammonium carbonate concentration, the liquid-to-solid ratio, air flow rate and mechanical stirring rate. The controlling step for the leaching kinetics was identified and the effects of different parameters were investigated. This research is potentially beneficial for further optimisation of the copper leaching process and the whole process design for copper recycling after incorporating with solvent purification and electrowinning of the copper-rich solution.