Selective recovery of tin by solvent extraction using branched tertiary phosphine oxides
AssigneeAmerican Cyanamid Company
InventorsWilliam A. Rickelton, Richard J. Boyle
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Abstract
Disclosed are processes for the selective extraction of tin from aqueous acidic solutions bearing tin and other metal cations. Branched tertiary phosphine oxides comprising at least two branches per alkyl group show higher extraction coefficients, E, for tin than other metals, e.g. zinc (III), iron (II), iron (III), copper (II) and lead (II). Novel compositions for selectively extracting tin comprising combinations of symmetrical branched phosphine oxides and unsymmetrical phosphine oxides are also disclosed.
Claims12
A process for the selective extraction of tin from aqueous acid solutions to the substantial exclusion of other metals present, which process comprises (1) contacting said aqueous acid solution with an extractant composition comprising a branched phosphine oxide compound having the formula:
- R.sub.3 P.dbd.O
- wherein R is selected from the group consisting of alkyl of from about 6 to about 16 carbon atoms and wherein R comprises at least two branches per alkyl group, alone, or in further combination with an unsymmetrical phosphine oxide compound of the formula:
- ##STR4## wherein R.sup.1, R.sup.2 and R.sup.3 are each independently selected from alkyl groups of from about 6 to about 16 carbon atoms, and at least one of the R.sup.1, R.sup.2 and R.sup.3 groups being different from the other said groups;
- (2) separating the resulting phosphine oxide--tin complex from said aqueous solution;
- and (3) recovering the tin from said complex.
Dependencies are inferred from the claim text.