Metal recovery from waste printed circuit boards: A review for current status and perspectives

Large amounts of waste electric and electronic equipment (WEEE) has been produced due to continuous technological innovation and the improvement of living standards. Based on the rich metal compositions, waste printed circuit boards (WPCBs) are considered as the most valuable component among WEEE. The recycling of metals from WPCBs with inappropriate methods or in informal sectors has been a profitable business, which, however, wastes resources and is harmful to environment and human health. Proper methods that are ecofriendly to recover metals from WPCBs are therefore urgent and essential for both industries and policy makers. In this article, the technology details of metal recycling processes are reviewed based on past research efforts to provide a complete image of the current status. The advantages and problems of several conventional methods are summarized and compared according to cost, environmental impact, and recovery efficiency. Possible approaches for improving mechanical treatment and bioleaching methods, are accordingly analyzed. Novel hybrid processes, such as chelation technology & bioleaching process, green adsorption & chemical leaching process, etc., are put forward to open up possibilities of multi-technology coupling processes for metal recycling from WPCBs.