Selective Leaching of Platinum and Palladium by Sodium Chloride and Sodium Hypochlorite

Abstract

Platinum group metals, such as palladium (Pd) and platinum (Pt), are commonly used in a wide range of industrial applications as an elemental metal and various kinds of alloys. Conventionally, Pt and Pd were dissolved together followed by separation. It is difficult to recovery high-grade Pd and Pt from the primary raw materials and solid wastes. In this study, the selective leaching of Pd and Pt from a secondary resource by using sodium chloride and sodium hypochlorite has been investigated. Results indicate that about 100% of palladium could be initially extracted by using the 0.27 mol / l (active chlorine) sodium hypochlorite and 0.068 mol / l sodium chloride (NaCl) at pH1.2 and 298K in 1.5 hours or 0.005 mol/l sodium chlorate (NaClO₃) and 6.0 mol / l hydrochloric acid (HCl) at 298K in 0.5 hours. About 100% Pt could be extracted from the residue by using 0.47 mol / l sodium chlorate (NaClO3) and 12 mol / l hydrochloric acid (HCl) at 298K in 2 hours.