Recovery of Platinum Group Metals From S (1)

The use of molten salts as 'solvents' offers interesting possibilities for the treatment of ores, industrial by-products as well as scraps, allowing the development of processes that are mid-way between pyro- and hydrometallurgy, with the advantage of salts offering a wide choice of chemical and electrochemical properties. The molten mixtures can be fed to industrial electrolytic cells (electrometallurgy) where the reactions can take place. One example of this type of reactions is the selective chlorination using gaseous mixtures in a molten chloride salt mixture. Within the frame of the EU-financed project PLATIRUS (GA 730224), the possibility of selective chlorination of platinum group metals (PGM) contained in spent automobile catalyst samples, using a molten salt as reaction media was investigated. To predict the selective separating conditions of the PGMs from the sample matrix, the Pourbaix type E-pO2 diagrams of the most relevant components in the spent catalyst were compared with those of relevant chlorinating gaseous mixtures, i.e. Cl2/O2. This allowed to predict the optimal chlorinating conditions, which were tested and confirmed experimentally using Cl2 gas.