Theory and practice on recovery of platinum group metals from spent auto catalysts by reduction-smelting copper trapping method

The basic theory on recovery of platinum group metals from spent auto catalyst by reduction smelting copper trapping method was studied and the experimental verification was carried out. The ΔGT Θ-T equations of possible reactions in the whole process were obtained through theoretical calculation, and the analysis shows that the platinum group metals oxides are reduced to metallic state in preference to copper oxide, and the actual reduction smelting temperature should be lower than 1500 ℃. The phase diagram and viscosity of CaO-Al2O3-SiO2 smelting slag containing MgO system were calculated, and the amount of CaO and SiO2 should be controlled in the smelting process to implement choice of slag type. It can be seen from the copper-platinum group metals phase diagrams that copper can form the continuous solid solution with platinum palladium and rhodium. The feasibility of recovering platinum group metals from spent auto catalyst by copper trapping method is proved theoretically. The recoveries of platinum, palladium and rhodium are 98.2%, 99.2% and 97.6%, respectively, under the appropriate conditions by practical experimental verification. © 2019, Science Press. All right reserved.