发明授权
US4662938A Recovery of silver and gold 失效
回收银和金

Recovery of silver and gold
摘要:
This invention provides processes for selectively recovering silver and gold values from feed materials containing both precious metals, and comprises leaching the feed material with a hot ferric chloride-acid brine leach solution for a time sufficient to dissolve the silver, but wherein the gold is not dissolved and remains with the solid residue. The silver-containing ferric chloride-acid brine leachate is separated from the solid residue containing the gold. The leach solution is then cooled to precipitate the silver as silver chloride. The solid residue containing the gold is then leached with hypochlorous acid to dissolve the gold, and after separating the solids form the gold-containing hypochlorous acid leach solution, the gold is precipitated by contacting the solution with sulfur dioxide. The silver chloride may be further processed in a fused salt electrolysis step at or above the melting point of silver to produce a substantially pure silver and chlorine gas. The chlorine gas can then be used in regenerating the spent ferric chloride-acid brine leach solution.
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