Recovery of ultrafine copper particles from metal components of waste printed circuit boards

Waste printed circuit boards (WPCBs) contain plenty of valuable resources and hazardous materials, considered both an attractive secondary resource and an environmental contaminant. In the current research, a hydrometallurgical process combined ammonia leaching and solvent extraction to recover copper from the metal components of WPCBs, and the production of ultrafine copper particles stripped from a solution was investigated. The results of copper oxidation leaching indicated that 96.7% of copper can be recovered at a temperature of 35 °C for a leaching duration of 2 h with ammonium sulfate and ammonia concentration of 2 mol/L at a solid:liquid ratio of 1:10 g/cm3. The treatment of leach liquor for solvent extraction of copper with LIX 84 showed that 50% LIX 84 in kerosene, a 3 min period of equilibration, and a pH of 10 were sufficient for the extraction of Cu(II) and 99.6% copper can be recovered from the leached solution. The results of the preparation of copper particles from stripped solution showed that mono-dispersed ultrafine copper particles with a diameter of approximately 1.5 μm were obtained from the stripped solution containing 39.25 g/L Cu2 + ion, oleic acid used as surfactant, and sodium hypophosphite as reductant. As the purity of the copper extracted from the leaching system was high and the as-synthesized ultrafine copper particles possess excellent anti-oxidation property, this WPCB metal-component hydrometallurgical recycling process has the potential of recovering high-purity ultrafine copper particles.