Process for leaching precious metals with hydrogen-peroxide and a cyanide leaching solution

US5250272A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Helmut Knorre · Seligenstadt, DE
• Juergen Loroesch · Hanau, DE
• Steven Gos · Hanau, DE
• Mathias Stoll · Bad Bederkesa, DE
• Annette Ziegler · Offenbach, DE

Key dates

• Filing date: Jun 18, 1992
• Grant date: Oct 5, 1993
• Expiry date: Jun 18, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22B11/08
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process for leaching gold and silver from ores and ore concentrates is disclosed using a cyanide leaching solution and hydrogen peroxide and maintaining an oxygen concentration of 2 to 20 Mg of O.sub.2 /liter. In the invention, leaching takes place in the presence of decomposition catalysts and preferably the formed cyano-complexes are separated during leaching from the leach solution. Decomposition catalysts are manganese compounds, present as 0.01 to 1 mg computed as Mn/liter of barren solution, or 1 to 50 mg computed as Mn per kg of ore slurry, or they are inorganic or organic polymers or carbon. Activated charcoal is preferred and simultaneously adsorbing cyano-complexes of precious metals. The process offers lowered consumption of H.sub.2 O.sub.2 and possibly cyanide and maximum gold yield in a shortened leaching time.