Leaching of Pt, Pd and Rh from Automotive Catalyst Residue in Various Chloride Based Solutions

Platinum-group metals (PGM) are important precious metals in many industrial fields. However, their natural resource deposits are strictly limited. Accordingly, their recycling process from wastes and/or secondary resources must be considered. In this study, the leaching of PGM from automotive catalyst residue was performed based on the formation of their chloro-complexes in various concentration of acidic solution. The recovery of platinum, palladium and rhodium from the samples after hydrogen reduction pretreatments was examined in the leaching process by using a mild solution mixture of NaClO–HCl and H2O2 at 65 � C for 3 h. Effect of other solution mixtures on the extraction of the precious metals was also compared with NaClO–HCl–H2O2, such as HCl–H2O2 and NaClO–HCl. The optimum condition to dissolve platinum,