The Solution Chemistry and Solvent Extraction Behaviour of Cu, Fe, Ni, Zn, Pb, Sn, Ag, As, Sb, Bi, Se and Te in Acid Chloride Solutions Reviewed from the Standpoint of PGM Refining

Abstract

In the solvent extraction separation of Platinum Group Metals (PGM) from industrial chloride liquors, the presence of impurity elements may cause processing complications as they tend to coextract. Strip solution contamination may be an obvious occurence as well as buildup in the organic phase and third phase formation. In order to design scrubbing stages for their removal or to avoid coextraction altogether, it is important to have a solid understanding of the chloro-chemistry of the impurity elements. In addition, reviewing the chloride solvent extraction systems previously investigated provides additional information for process design. The review covers the elements Cu, Fe, Ni, Zn, Pb, Sn, Ag, As, Sb, Bi, Se and Te. Most elements exhibit anionic chlorocomplexation in HCl medium at >1.0 M and this is why they extract via an ion-pair formation mechanism with strong basic extractants (amines)as well as weaker ones (TBP, TOPO, 8-hydroxyquinoline)

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Notes on contributors

V. H. APRAHAMIAN

Now with Metaux Precieux S.A. Metalor, Switzerland

G. P. DEMOPOULOS

To whom correspondence should be addressed