Solvent extraction: The coordination chemistry behind extractive metallurgy

A Matthew Wilson, Philip Bailey, Peter A Tasker, Jennifer R Turkington, Richard A Grant, Jason B Love

Research output: Contribution to journalArticlepeer-review

Abstract

The modes of action of the commercial solvent extractants used in extractive hydrometallurgy are classified according to whether the recovery process involves the transport of metal cations, Mn+, metalate anions, MXxn-, or metal salts, MXx into a water-immiscible solvent. Well-established principles of coordination chemistry provide an explanation for the remarkable strengths and selectivities shown by most of these extractants. Reagents which achieve high selectivity when transporting metal cations or metal salts into a water-immiscible solvent usually operate in the inner coordination sphere of the metal and provide donor atom types or dispositions which favour the formation of particularly stable neutral complexes that have high solubility in the hydrocarbons commonly used in recovery processes. In the extraction of metalates, the structures of the neutral assemblies formed in the water-immiscible phase are usually not well defined and the cationic reagents can be assumed to operate in the outer coordination spheres. The formation of secondary bonds in the outer sphere using, for example, electrostatic or H-bonding interactions are favoured by the low polarity of the water-immiscible solvents.

Original languageEnglish
Pages (from-to)123-134
JournalChemical Society Reviews
Volume43
Issue number1
Early online date3 Oct 2013
DOIs
Publication statusPublished - 7 Jan 2014

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