Efficient Resource Utilization and Environmentally Safe Recovery of Platinum Group Metals from Spent Automotive Catalysts via Copper Smelting

Spent automotive catalysts (SAC) not only contain significant amounts of platinum group metals (PGMs) but also hazardous heavy metals, rendering them a solid waste. A harmless technology for the efficient recovery of PGMs through copper smelting has been proposed. By investigating the effects of the CaO/SiO2 mass ratio and Al2O3 content on the properties of the slag, the composition of the slag was adjusted. The influence of copper dosage, Na2B4O7 dosage, smelting temperature, and smelting time on the recovery efficiency of PGMs was also discussed. The determined composition of the target slag was 36.44 wt% CaO, 45.56 wt% SiO2, 12.00 wt% Al2O3, and 6.00 wt% MgO. The optimal processing conditions included 12 wt% Cu, 4 wt% Na2B4O7, smelting temperature 1450 °C, and smelting time 90 min. Ultimately, the recovery efficiency of PGMs reached 99.5%. Compared to traditional plasma furnace smelting methods, PGMs were efficiently recovered at a lower melting temperature. A pilot-scale experiment with a mass of 30 kg also achieved a recovery rate of over 99% for PGMs. TCLP results indicate that the heavy metals were immobilized within the glass slag.