Physical pre-concentration and ammonium leaching of metal copper from waste printed circuit boards

Abstract

Waste printed circuit boards (WPCBs) is the most valuable component in electronic waste, which is accompanied by potential environmental threats due to the presence of hazardous substances. In this study, a gradient enrichment approach including physical pre-concentration and leaching deep enrichment was proposed to realize the efficient recovery of copper in WPCBs. Shaking table separation, a typical gravity separation technique, was used to concentrate copper in WPCBs particles with different sizes. The results show that when the particle size is limited, the recovery of copper increases with the decrease of particle size, from 90.06% of 0.5–0.25 mm to 98.07% of −0.045 mm. Subsequently, ammonium leaching system was used to deep recover copper from copper concentrate. The effects of two key parameters, leaching time and leaching temperature, on the leaching rate were studied. Under optimal conditions, the leaching rate of copper increases with the decrease of particle size, from 80.23% of 0.5–0.25 mm to 95.08% of −0.045 mm. The leaching time and temperature (5–45 °C) can promote the leaching. A green and environmentally friendly gradient recovery technical approach was proposed for recover copper from WPCBs to present its maximum utilization value.