| 摘要 |
PURPOSE:To easily obtain high-purity Au by washing an Au-containing organic phase after Au extraction with an acid aqueous solution of a specific concentration and by allowing impurity Ag contained in the organic phase to pass into an aqueous phase at the time of carrying out Au refining by a solvent extraction method. CONSTITUTION:An Au material containing Ag, etc., as impurities is dissolved in aqua regia. Next, Au is extracted with an extraction reagent such as methyl isobutyl ketone, diisobutly ketone, diisopropyl ketone, etc. After that, an Au- containing organic phase after Au extraction is washed with an aqueous phase consisting of an acid of 2-16N concentration (e.g., hydrochloric acid, sulfuric acid) so as to allow impurity Ag contained in the organic phase to pass into the aqueous phase. Subsequently, the Au-containing organic phase is subjected to reverse extraction with an alkali solution to allow Au to pass into the alkali solution and then reduced, so that desired high-purity Au powder is obtained. In this way, high-purity Au of 99,99% purity can be easily obtained.
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