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US 5,135,652 AGranted
Method for the solvent extraction of zinc
AssigneeCominco Ltd.
InventorDaniel A. D. Boateng
Life of this patent
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AssigneeCominco Ltd.
InventorDaniel A. D. Boateng
Estimating the term…
Zinc is selectively extracted from zinc sulfate solutions that may also contain sulfuric acid and amounts of other metals with an organic extractant mixture containing both organic substituted phosphoric acid and organic substituted thiophosphinic acid. The phosphoric acids are preferably chosen from mono- and di-2-ethylhexylphosphoric acids and mixtures thereof, and the phosphinic acids are preferably chosen from bis- 2, 4, 4-trimethylpentyl mono- and dithiophosphinic acids. The use of an extractant mixture of the dithiophosphinic acid with mono- and di-2-ethylhexyl phosphoric acids or an extractant mixture of the dithiophosphinic acid with di-2-ethylhexylphosphoric acid is preferred. The pH during zinc extraction is controlled at a value in the range of about 1.3 to 5. Control of pH is carried out either by neutralization or by acid extraction with an organic amine-type extractant. The acid content of the feed solution may be reduced by neutralization or acid removal by dialysis. The solvent extraction of zinc or zinc and acid from feed solution may be carried out co-, counter- or cross-currently in one or more stages. The preferred extraction method is dualcircuit, side-by-side, simultaneous zinc and acid extraction. The use of the mixed extractant for zinc is more effective than extraction with the component extractants by themselves.
A method for the selective extraction of zinc from an acidic aqueous solution containing zinc sulfate and essentially free of ferric iron and co-extractable metals including the steps of contacting said solution with an extractant mixture containing an extractant for zinc chosen from the group consisting of mono-2-ethylhexylphosphoric acid, di-2-ethylhexylphosphoric acid, a mixture of mono-2-ethylhexylphosphoric acid and di-2-ethylhexylphosphoric acid, and an extractant for zinc chosen from the group consisting of bis- 2, 4, 4-trimethylpentylmonothiophosphinic acid and bis-2,4,4-trimethylpentyldithiophosphinic acid for the formation of a zinc extract containing said zinc and of a zinc extraction raffinate said extractant mixture having a volume ratio of said phosphoric acid or mixture of phosphoric acids to said thiophosphinic acid in the range of about 1:1 to 6:1;
A method for the selective extraction of zinc from an acidic aqueous solution containing zinc sulfate and essentially free of ferric iron and co-extractable metals including the steps of contacting said solution with an extractant mixture containing an extractant for zinc chosen from the group consisting of mono-2-ethylhexylphosphoric acid, di-2-ethylhexylphosphoric acid, a mixture of mono-2-ethylhexylphosphoric acid and di-2-ethylhexylphosphoric acid, and an extractant for zinc chosen from the group consisting of bis- 2,4,4-trimethylpentylmonothiophosphinic acid and bis-2,4,4-trimethylpentyldithiophosphinic acid for the formation of a zinc extract containing said zinc and of a zinc extraction raffinate;
A method for the selective extraction of zinc from an acidic aqueous solution containing zinc sulfate and essentially free of ferric iron and co-extractable metals including the steps of contacting said solution with an extractant mixture containing an extractant for zinc chosen from the group consisting of mono-2-ethylhexylphosphoric acid, di-2-ethylhexylphosphoric acid, a mixture of mono-2-ethylhexylphosphoric acid and di-2-ethylhexylphosphoric acid, and an extractant for zinc chosen from the group consisting of bis- 2,4,4-trimethylpentylmonothiophosphinic acid and bis-2,4,4-trimethylpentyldithiophosphinic acid for the formation of a zinc extract containing said zinc and of a zinc extraction raffinate;
A method for the selective extraction of zinc from an acidic aqueous solution containing zinc sulfate and essentially free of ferric iron and co-extractable metals including the steps of contacting said solution with an extractant mixture containing an extractant for zinc chosen from the group consisting of mono-2-ethylhexylphosphoric acid, di-2-ethylhexylphosphoric acid, a mixture of mono-2-ethylhexylphosphoric acid and di-2-ethylhexylphosphoric acid, and an extractant for zinc chosen from the group consisting of bis- 2,4,4-trimethylpentylmonothiophosphinic acid an bis-2,4,4-trimethylpentyldithiophosphinic acid for the formation of a zinc extract containing said zinc and of a zinc extraction raffinate;
Dependencies are inferred from the claim text.