Method of recovering metals

摘要

Cobalt and/or nickel are recovered from a normally acid-resistant alloy by treating said alloy with an aqueous hydrochloric acid/chloride nitrate solution in which the hydrogen chloride concentration is less than 20.2% by weight. The nitrate may be any water-soluble inorganic nitrate e.g. of an alkali metal and I to 1.5 parts by weight to 3 parts of hydro-chloric acid may be used. The solution may be treated with air and calcium carbonate to precipitate hydrated chromium and iron oxides which are removed by filatration, followed by treatment with chlorine and calcium carbonate to precipitate cobalt as hydrated cobaltic oxide at pH 3. Filtration followed by addition of hydrated lime precipitates the nickel as hydrated oxide.