To provide a method for surely separating lead from ammonium hexachloroiridate (IV) containing lead regardless of a contained form of lead, and consequently collecting iridium at a high yield.
This refining method comprises the following steps (1) to (3) of: (1) dissolving ammonium hexachloroiridate (IV) into hydrochloric acid by adding ammonium hexachloroiridate (IV) containing lead in the hydrochloric acid, suspending it therein, and adjusting an oxidation-reduction potential, while heating the obtained suspension liquid; (2) selectively extracting lead contained in the solution into the extractant to separate lead, by adding neodecanoic acid of the extractant into the obtained solution and adding an alkali to adjust the pH; and (3) collecting ammonium hexachloroiridate (IV) by adjusting the concentration of the hydrochloric acid, the concentration of ammonium chloride and an oxidation-reduction potential in the solution from which lead has been removed, and then heating the solution to crystallize ammonium hexachloroiridate (IV).
COPYRIGHT: (C)2008,JPO&INPIT
Takashi Sakamoto
Hidemasa Nagai
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