Highly Selective and Efficient Recovery of Pd, Pt, and Rh from Precious Metal‐Containing Industrial Effluents with Silica‐Based (Poly)Amine Ion Exchangers

Abstract

Abstract The recovery of Pd, Pt, and Rh from batches of authentic industrial precious metal refinery (PMR) effluents containing large amounts of Ni, Cu, and Fe ions and relatively small amounts of the expensive Pt, Pd, and Rh ions was investigated with silica‐based anion exchangers containing monoamine, ethylenediamine, and diethylenetriamine functionalities. All platinum group metal (PGM) recoveries have proven to be highly selective over various base metal ions, such as Cu2+. Quantitative recovery of Pd and Pt from some of the PMR effluents was effected by these ion exchangers, whereby HCl appears to be a powerful desorbent. Moreover, in most cases, Pd and Pt have been completely stripped from the ion exchangers with thiourea or with a combination of thiourea and HCl. Rh recovery from a base metal refinery (BMR) effluent was found to be less efficient, with maximum adsorption values of just over 20% and with a maximum desorption of about 50%. Rh stripping after extraction from one of the PMR effluents appeared to be much more successful. The well‐known difficulties in Rh recovery can be largely attributed to the occurrence of several kinetically inert species in hydrometallurgical effluents.