PURPOSE:To almost quantitatively separate Rh from heavy metal impurities with simple operation and to improve the refining yield by heating the rhodium or mixed solution or mixed material containing this in mixed liquid of nitric acid and perchloric acid and further adding hydrogen peroxide. CONSTITUTION:The rhodium (besides pure salt of rhodium chloride or rhodium chloric acid, etc., containing the rhodium being under mixed state with a little quantity of the other hydrochloride of platinum group metal, etc.) or the mixed solution containing the rhodium (solution containing the other heavy metal of the rhodium recovery liquid, etc.) or the mixed material (hydrochloride precipitating material containing a large quantity of the other heavy metal, particularly, lead) is heated in the mixed liquid of nitric acid and perchloric acid. After that, the hydrogen peroxide is added to this and the perchloric acid is decomposed and cooled to make the rhodium the nitride and this is filtrated to separate this into the precipitating material and solution. By this method, the rhodium nitride solution separated from the other heavy metal chloride can be obtd. with sufficiently high reacting yield.
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