Leaching of Pt, Pd and Rh from automotive catalyst residue in various chloride based solutions

Platinum-group metals (PGM) are important precious metals ill many industrial fields. However, their natural resource deposits are strictly limited. Accordingly, their recycling process front 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 front the samples after hydrogen reduction pretreatments was examined it the leaching process by using it mild solution mixture of NaClO-HCl and H2O2 at 65 degrees C for 3 h. Effect of other solution mixtures oil the extraction of the precious metals was also compared with NaClO-HCl-H2O2, such its HCl-H2O2 and NaClO-HCl. The optimum condition to dissolve platinum, palladium and rhodium was achieved by the mixture of 3 vol% NaClO, 5 kmol.m(-3) HCl and addition of 1 vol% H2O2. The recovery of platinum, palladium and rhodium after 3 h leaching reaches 88%, 99%, 77%, respectively.