Electrochemical recycling of waste printed circuit boards in bromide media. Part I: preliminary leaching and dismantling tests

In the context of the large and increasing interest for an efficient and ecological recycling of the Waste Electrical and Electronic Equipments (WEEEs), we decide to evaluate the feasibility of an electrochemical recycling process for waste printed circuit boards (WPCBs) based on bromine-bromide leaching system. For this preliminary study, a perforated rotating drum chemical reactor (RDCR), interconnected with a divided electrochemical reactor (DER) in a closed hydraulic loop, was successfully used to dismantle consecutively three computer motherboards (CMB) after a minimal mechanical pre-treatment. Essentially, the base metals were leached at the RDCR level and the bromine-bromide system was regenerated at the DER level, simultaneously with the partial electrodeposition of dissolved metals. Even if the operating parameters were not optimized, each CMB was completely dismantled in around 18 h, with cathodic and anodic mean current efficiencies of 43.6% and 58.4%, respectively. Notably, grace to the proposed process, the remaining undissolved parts (fiberglass reinforced epoxy boards, electronic components, plastics, etc.) preserve their original shape and structure, allowing an easier consequent separation-classification and a more efficient and profitable recycling. Keywords: Waste printed circuit boards, metals recovery, electrochemical recycling, bromine-bromide leaching system, environmentally friendly process