| Summary: | The application of ammonium thiosulfate for the treatment of copper-gold ores has been
investigated. Leaching studies were conducted with copper minerals, copper minerals with gold
addition to solution and copper-gold samples of different copper and gold grades. The behaviour
of thiosulfate, tetrathionate and sulfate in solution was studied using ion chromatography.
The copper sulfide minerals chalcopyrite and enargite seem to be unreactive toward an
ammonium thiosulfate leach. Covellite and chalcocite leach to a slight extent in this leaching
system. The copper extractions of the sulfide minerals seem to be independent of the availability
of complexing agents. The copper oxide minerals cuprite and malachite showed high copper
extractions in the presence of sufficient lixiviant.
Experiments showed that both gold extraction and thiosulfate stability are influenced by a
combination of aeration and cupric ions in solution. High initial gold extractions were achieved
in an aerated solution in the presence of cupric ions. However, these conditions simultaneously
catalyzed thiosulfate degradation, resulting in gold precipitation. Therefore, it is important to
establish a balance between providing sufficient air and cupric ions for fast gold dissolution, and
to minimize the amount of air in the presence of cupric ions to prevent excessive thiosulfate
degradation. A promising potential alternative to these conditions is a 24 hour leach without
forced aeration. === Applied Science, Faculty of === Materials Engineering, Department of === Graduate
|
|---|
