Chemical Dissolution of Iridium Powder Using Alkali Fusion Followed by High-Temperature Leaching

The dissolution of iridium has been investigated with an alkali fusion treatment with Na 2 O 2 followed by leaching in HCl solution.Alkali fusion with Na 2 O 2 allows Ir to be easily oxidized to IrO 2 , which is transformed to a high oxidation state through the binding of Na-Ir-O at 600 C for 4 h.From the fused mixture, with molar ratio of 1 : 2:0 (Ir : Na 2 O 2 ), Ir can be leached completely at 130 C using an HCl solution with a concentration above 3 M.Moreover, the leaching with 3 M HCl at 130 C can dissolve Ir from the mixture that was fused at 600 C, regardless of molar ratio of Na 2 O 2 .Ir can also be completely dissolved at 70 C or less when the fused mixture has a 1 : 2:0 ratio.