# US 5,344,567 A · Recovery of indium by solvent extraction using trialkylphosphine oxides

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- Number: US 5,344,567 A
- Document ID: US5344567A
- Status: Granted
- Kind: A
- Application number: 08/083,240
- Filed: 1993-06-29
- Granted: 1994-09-06
- Earliest claimed: 1993-06-29
- Assignees: Cyanamid Canada Inc.
- Inventors: William A. Rickelton
- Web page: https://patentgrep.com/patent/US5344567A

## CPC

- C22B 3/383: {Tervalent phosphorus oxyacids, esters thereof}
- C22B 3/3846: {Phosphoric acid, e.g. (O)P(OH)3}
- C22B 3/408: {using a mixture of phosphorus-based acid derivatives of different types}
- C22B 58/00: Obtaining gallium or indium {(treatment or purification of solutions by liquid-liquid extraction, by ion-exchange or by adsorption C22B3/20)}
- Y02P 10/20: Recycling
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

This invention relates to a process for the recovery of indium from aqueous acid solutions. More particularly, it concerns the use of a combination of a dialkyl phosphoric acid and a mixture of trialkyl phosphine oxides to extract indium from acidic sulphate leach liquors.

## Claims

### Claim 1

A process for the extraction of indium from aqueous acidic liquors, which process comprises:
(a) contacting said indium-containing acid solution with a solvent extractant combination comprising
(i) a dialkyl phosphoric acid and
(ii) a tertiary phosphine oxide selected from 1) a mixture containing at least four different components each of the same general formula RR.sup.i R.sup.ii PO wherein R, R.sup.i, R.sup.ii are the same or different saturated hydrocarbon radicals of 6 to about 16 carbon atoms, and at least two components of said tertiary phosphine oxide mixture being unsymmetrical tertiary phosphine oxides containing at least one R, R.sup.i, R.sup.ii group different from the other said groups; 2) a mixture of branched tertiary phosphine oxide compounds selected from those of the formulae:
R.sup.iii R.sup.iv.sub.2 PO and
R.sup.iv.sub.3 PO
wherein R.sup.iii and R.sup.iv are selected from saturated hydrocarbon radicals of from about 6 to about 16 carbon atoms and wherein R.sup.iii is unbranched and R.sup.iv comprises at least two branches per hydrocarbon radical; or a combination of 1) and 2);
(b) separating a resulting dialkyl phosphoric acid-phosphine oxide-indium complex from said acid solution; and
(c) recovering the indium from said complex.

### Claim 2 (depends on 1)

A process as defined in claim 1 wherein said tertiary phosphine oxide mixture contains four components R.sub.3 PO, R.sup.i.sub.3 PO, R.sub.2 R.sup.i PO and RR.sup.ii.sub.2 PO in which R is hexyl and R.sup.i is octyl.

### Claim 3 (depends on 2)

A process as defined in claim 2 wherein said tertiary phosphine oxide mixture is prepared by the reaction of phosphine and about 90:10 to about 10:90 mixture of 1-hexene and 1-octene, followed by oxidation.

### Claim 4 (depends on 3)

A process as defined in claim 3 wherein said tertiary phosphine oxide mixture is derived from about 60:40 to about 40:60 mixture of 1-hexene and 1-octene.

### Claim 5 (depends on 4)

A process as defined in claim 4 wherein said tertiary phosphine oxide mixture is derived from a 60:40 mixture of 1-octene and 1-hexene.

### Claim 6 (depends on 1)

A process as defined in claim 1 wherein said tertiary phosphine oxide mixture contains two components R.sup.iii.sub.3 PO, and RR.sup.iii.sub.2 PO in which R.sup.iii is 2,4,4-trimethylpentyl and R is octyl.

### Claim 7 (depends on 6)

A process as defined in claim 6 wherein said tertiary phosphine oxide mixture is prepared by the reaction of phosphine and about 90:10 to about 10:90 mixture of 2,4,4-trimethyl-1-pentene and 1-octene, followed by oxidation.

### Claim 8 (depends on 3)

A process as defined in claim 3 wherein said tertiary phosphine oxide mixture is derived from about 60:40 to about 40:60 mixture of 2,2,4-trimethyl-1-pentene and 1-octene.

### Claim 9 (depends on 8)

A process as defined in claim 8 wherein said tertiary phosphine oxide mixture is derived from a 60:40 mixture of 2,4,4-trimethyl-1-pentene and 1-octene.

### Claim 10 (depends on 1)

A process as defined in claim 1 wherein said dialkylphosphoric acid is di(2-ethylhexyl)phosphoric acid.

### Claim 11 (depends on 1)

A process as defined in claim 1 wherein said solvent extractant combination is dissolved in a water-immiscible hydrocarbon diluent.

### Claim 12 (depends on 11)

A process as defined in claim 11 wherein said hydrocarbon diluent is an aliphatic hydrocarbon diluent.