A new platinum (Pt) extraction process by an alloy formation technique using calcium (Ca) or magnesium (Mg) vapor and successive leaching with an aqueous solution was investigated. Pure Pt metal plate or powder were contacted with Ca or Mg vapor at constant temperatures ranging between 873 and 1173 K for 3 to 12 hours, and Ca-Pt or Mg-Pt compounds were synthesized. The interaction of Pt and reactive metal vapor was studied. The obtained compounds were then dissolved in an aqueous HC1 solution or in aqua regia at room temperature. Pt was recovered from the leaching solution by a conventional precipitation technique, and the amount of Pt recovered by precipitation was evaluated. After the vapor treatment, 100% of Pt in the compound was dissolved in aqua regia for 1 h, whereas only 14% of the untreated pure Pt was dissolved after the reaction with aqua regia for 4 h.
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