A combined process of reverse flotation and slurry electrolysis for step-by-step recovery of copper and gold from waste printed circuit boards.

Waste printed circuit boards (WPCBs) constitute a significant component of e-waste, harboring abundant recyclable valuable metals. The ongoing increase in e-waste requires an efficient recycling method to recover valuable metals, thereby enhancing the recycling efficiency. In this study, an efficient and environmentally friendly combined process of reverse flotation and two-step slurry electrolysis was used to recover copper and gold from WPCBs. In the reverse flotation process, tannic acid was conducted using as a dispersant to enhance the separation selectivity, and the recoveries of copper and gold from WPCBs reached 94.57 % and 98.01 % respectively. A new high-efficiency alkaline slurry electrolysis system with ethylenediamine (en), NH·HO, (NH)SO and Cu was devoted to recover copper from WPCBs. Under the optimal conditions, the leaching ratio, electrodeposition recovery and current efficiency of copper from WPCBs were 99.57 %, 97.53 %, and 65.64 %, respectively. Afterwards, for the anode residue after copper recovery, a kind of electrolyte consisting only of potassium iodide (KI) was proposed for recovering gold by slurry electrolysis. Under the optimal conditions, the leaching ratio, electrodeposition recovery and current efficiency of gold from WPCBs were 99.08 %, 89.12 % and 3.57 %, respectively. Thus, the copper and gold from WPCBs are recovered step by step via slurry electrolysis in different systems, it is expected to realize the application of slurry electrolysis in the e-waste industry.