Separation of Palladium, Platinum and Rhodium from Metallic Mixture by Selective Dissolution with Hydrochloric Acid Solutions Containing Oxidizing Agents

ABSTRACT

Platinum group metals are widely used in the manufacture of advanced materials due to their excellent physical and chemical properties. Especially, palladium (Pd), platinum(Pt), and rhodium(Rh) are used as catalysts for automobiles. In general, combination of pyrometallurgical and hydrometallurgical process is necessary to recover PGMs. In this work, the separation of Pd, Pt, and Rh from the metallic mixture was investigated by selective dissolution using HCl solutions containing oxidizing agents such as H₂O₂ and NaClO₃. As a diluent for the leaching medium, either water or ethylene glycol (EG) was employed and the dissolution behavior of the three metals was compared. Selective dissolution of 99.9% Pd from the metallic mixture was achieved by using 1 M HCl and 1.225 M M H₂O₂ (H₂O medium, 40°C, 30 min), while that of 99.9% Pt was possible by using 5 M HCl and 0.5 M NaClO₃ (H₂O medium, 60°C,120 min). By these two-step dissolution, Rh metal remained in the residue. A simple process was proposed to separate Pd, Pt, and Rh from their metallic mixture by selective dissolution.

KEYWORDS:

• Pd-Pt-Rh metallic mixture
• separation
• selective dissolution
• HCl
• oxidizing agent

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by a grant from the National Research Foundation of Korea [2018R1D1A1B07044951].