Sumitomo Metal Mining Company, Ltd.

Masushi Kasai

Satoshi Asano

Shinichi Heguri

Yoshiaki Manabe

Harumasa Kurokawa

A method of efficient separation/purification for obtaining high-purity silver chloride which eliminates the necessity of a pretreatment of a refining intermediate comprising sparingly soluble silver compounds and impurity elements when silver chloride is separated from the refining intermediate and purified to a high degree and which enables the silver chloride to be used as a raw material to give high-purity silver metal without necessitating the pyrometallurgical refining or electro-refining of the silver metal. The method is characterized by comprising: a leaching step in which the refining intermediate is leached with an aqueous sulfite solution to extract silver with the solution to thereby form a silver-containing liquid resulting from the leaching and an insoluble residue; a silver chloride generation step in which the liquid resulting from the leaching is neutralized and acidified to precipitate silver chloride and thereby form the silver chloride and a mother liquor; and a silver chloride purification step in which the silver chloride is oxidized in an acidic aqueous solution by adding an oxidizing agent to dissolve and separate impurity elements and thereby form purified silver chloride and a solution containing the impurity elements.

Method of separation/purification for high-purity silver chloride, and process for producing high-purity silver by the same

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.

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Niihama, Japan

Masushi Kasai