Process for mutual separation of platinum group metals
First Claim
1. A process for mutual separation of platinum group metals (PGM) from a raw material which also contains impurity elements, comprising the following steps:
- (1) first step, wherein the raw material containing PGM is leached in the presence of an oxidant while being suspended in a hydrochloric acid solution to prepare the leach liquor containing the PGM, (2) second step, wherein the leach liquor prepared in the first step is separated by solvent extraction with diethylene glycol dibutyl ether into the organic phase containing the impurity elements and raffinate, (3) third step, wherein the raffinate prepared in the second step is treated by solvent extraction with an alkyl sulfide to extract palladium and the loaded solvent is then treated by stripping, to prepare the stripping liquor containing palladium and raffinate, (4) fourth step, wherein the raffinate prepared in the third step is separated by solvent extraction with bis(2-ethylhexyl)phosphoric acid into the organic phase containing cationic impurity elements and raffinate, (5) fifth step, wherein the raffinate prepared in the fourth step is hydrolyzed in the presence of an oxidant, after being adjusted at a pH of 5 to 12, to prepare the precipitate containing iridium, ruthenium and rhodium, and aqueous solution containing platinum, (6) sixth step, wherein the precipitate prepared in the fifth step is leached in the presence of an oxidant in a strongly alkaline aqueous solution kept at a pH of 12 or more, to prepare the residue containing iridium and rhodium, and leach liquor containing ruthenium, and (7) seventh step, wherein the residue prepared in the sixth step is dissolved in a hydrochloric acid solution to prepare the aqueous solution containing iridium and rhodium, the aqueous solution is treated by solvent extraction with tributyl phosphate to extract iridium, and the loaded solvent is then treated by stripping, to prepare the stripping liquor containing iridium and raffinate containing rhodium.
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Abstract
A process for mutual separation of platinum group metals (PGM), wherein highly stable compounds and steps are used to efficiently remove impurity elements while preventing increase of impurity content relative to that of the PGM in the mother liquor and also preventing decomposition of a chloro complex, and palladium, platinum, iridium, ruthenium and rhodium are separated mutually in such a way that each of the separated PGM has a sufficient purity to be a commercial product. A process for mutual separation of PGM, comprising the first step for leaching a raw material containing PGM and impurity elements, second step for removing the impurity elements from the leach liquor by solvent extraction, third step for recovering palladium from the raffinate, fourth step for removing cationic impurity elements from the raffinate by solvent extraction, fifth step for recovering platinum from the raffinate by hydrolysis, sixth step for recovering ruthenium from the precipitate by leaching, and seventh step for recovering iridium by solvent extraction to prepare the stripping liquor containing iridium and raffinate containing rhodium.
21 Citations
18 Claims
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1. A process for mutual separation of platinum group metals (PGM) from a raw material which also contains impurity elements, comprising the following steps:
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(1) first step, wherein the raw material containing PGM is leached in the presence of an oxidant while being suspended in a hydrochloric acid solution to prepare the leach liquor containing the PGM, (2) second step, wherein the leach liquor prepared in the first step is separated by solvent extraction with diethylene glycol dibutyl ether into the organic phase containing the impurity elements and raffinate, (3) third step, wherein the raffinate prepared in the second step is treated by solvent extraction with an alkyl sulfide to extract palladium and the loaded solvent is then treated by stripping, to prepare the stripping liquor containing palladium and raffinate, (4) fourth step, wherein the raffinate prepared in the third step is separated by solvent extraction with bis(2-ethylhexyl)phosphoric acid into the organic phase containing cationic impurity elements and raffinate, (5) fifth step, wherein the raffinate prepared in the fourth step is hydrolyzed in the presence of an oxidant, after being adjusted at a pH of 5 to 12, to prepare the precipitate containing iridium, ruthenium and rhodium, and aqueous solution containing platinum, (6) sixth step, wherein the precipitate prepared in the fifth step is leached in the presence of an oxidant in a strongly alkaline aqueous solution kept at a pH of 12 or more, to prepare the residue containing iridium and rhodium, and leach liquor containing ruthenium, and (7) seventh step, wherein the residue prepared in the sixth step is dissolved in a hydrochloric acid solution to prepare the aqueous solution containing iridium and rhodium, the aqueous solution is treated by solvent extraction with tributyl phosphate to extract iridium, and the loaded solvent is then treated by stripping, to prepare the stripping liquor containing iridium and raffinate containing rhodium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification