Separation and recycling of Au and Ag from waste light-emitting diodes.

Waste light-emitting diodes (LEDs) contain rare and precious metals which have attracted wide attention due to their high resource. In this study, experimental research was conducted on the separation and recycling of Au and Ag from LEDs. Firstly, thermal treatment and sieving were done to separate and enrich the metals in LEDs. With the constant heating rate of 10°C/min to 450°C under air atmosphere, the metals could be effectively separated from organics and the rare metals Au and Ag mainly concentrate in particles with a diameter ≤600 μm, whose concentration is about 1816 and 1429 mg/kg, respectively. Then, a mix-acid system of HCl-CHCOOH was introduced to leach Au and Ag from the enriched sample. The results show that the HCl-CHCOOH system could effectively leach Au and Ag, and the leaching performance of Au and Ag can reach 95.4% and 96.2%, respectively under the recommended conditions (total acid concentration 5 mol/L, HCl:CHCOOH = 4:1, leaching temperature 80°C, solid-liquid ratio 1:100, leaching time 5 h). The study can provide a new option for recycling of waste LEDs, which also provide a more environment-friendly method for Au and Ag leaching from industrial wastes.