The United States of America As Represented by the Secretary of

Mnr Reprossesing, Inc.

George M Potter

Jerry L Huiatt

Melvin D Shurtz

Arthur Bergmann

Ulrich Haidlen

A process is described by which copper and optionally silver and gold are recovered from sulfide and oxide ores, concentrates or slag, which contain the metals. The particulate materials are treated with an aqueous solution of an alkali cyanide or alkaline earth cyanide, the laden solution is filtered, if desired, a water-soluble sulfide compound is added to the laden solution or filtered laden solution, the laden solution is subsequently adjusted to a pH value below 5 by an addition of acid to precipitate the metal sulfide, which is filtered off, and the resulting hydrocyanic acid is recovered. The process steps of precipitation and filtration of the metal sulfide and the recovery of the free hydrocyanic acid contained in the filtrate are carried out under superatmospheric pressure of 1.5 to 15 bars. The precipitation is preferably effected at a pH value of 1.5 to 2.0. The free hydrocyanic acid is recovered as alkali cyanide or alkaline earth cyanide and is recirculated to the leaching stage.

Process of recovering copper and of optionally recovering silver and

Molybdenite (MoS.sub.2) is recovered from copper sulfide flotation concentrates by froth flotation utilizing steam-air injection into the concentrate flotation pulp at a temperature of about 70.degree. to 100.degree. C. in the presence of activated carbon and soluble sulfide reagents.

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Tucson, AZ, United States of America

George M Potter