New Dissolution Process of Iridium to Hydrochloric Acid

Abstract

Iridium is used in various industrial products, one such application being a thin film catalysis of an oxygen-evolving anode. When iridium and iridium oxide are recovered and purified, they must be dissolved to aqueous solution due to them being chemically stable the dissolution in acid is difficult. Currently, it is dissolved with hydrochloric acid to which chlorine gas is injected but this leads to problems of safety and large environmental load. It is necessary to improve dissolving behavior of iridium in acid. In this study, a method to dissolve iridium to hydrochloric acid is developed. By mixture of metal Ir powder and CaCO3 was heated at 973 K or higher temperature, Ca2IrO4 and Ca4IrO6, complex oxides were synthesized. Iridium in the oxides formed can easily be dissolved in hydrochloric acid.