Newmont USA Limited

K Marc LeVier

Rong Yu Wan

Mineral materials comprising copper and precious metal are subjected to an acidic leach of the copper followed by an acidic thiocyanate leach of the precious metal.

Precious metal recovery using thiocyanate lixiviant

For removal of precious metal from thiocyanate leach solution, precious metal is transferred from precious metal-thiocyanate complex to precious metal-cyanide complex. Preparation of thiocyanate leach solution includes dissolving cyanide in an aqueous liquid and converting the cyanide to dissolved thiocyanate.

A heap with precious metal-containing mineral material with precious metal locked within sulfide mineralization is subjected to bio-oxidation followed by acidic thiocyanate leaching to dissolve precious metal. Sulfide sulfur is oxidized during both of the bio-oxidation and the thiocyanate leaching.

Precious metal-containing mineral material is subjected to an acidic thiocyanate leach to dissolve the precious metal as a precious metal-thiocyanate complex. A feed of the thiocyanate leach solution may include a large molar ratio of ferric iron to thiocyanate. Precious metal may be removed from pregnant thiocyanate leach solution, such as by transferring precious metal from precious metal-thiocyanate complex to precious metal-cyanide complex and then loading the precious metal-cyanide complex onto an adsorbent material. Remaining cyanide in the thiocyanate leach solution may be converted to thiocyanate for additional leaching of precious metal.

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Englewood, CO, United States of America

K Marc LeVier