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An Investigation of the Role of Sodium Carbonate and Silica in the Neutral/Alkaline Pressure Oxidation of Pyrite

Pressure oxidation of refractory gold ores containing carbonate minerals is conducted
under neutral/alkaline conditions in order to promote fast kinetics, reduced reagent consumption and suppressing the formation of elemental sulphur and CO2 (which reduces the effectiveness of the process). In this work, both the addition of sodium carbonate and the presence of silica were investigated during the pressure oxidation of pyrite in the presence of calcium carbonate. It was found that the shift to an alkaline leaching environment favours the formation of soluble sulphate products over anhydrite (an industrial scale), but that the increase in kinetics is likely due to an increase in pH and carbonate/bicarbonate concentrations. The presence of silica in the autoclave
induces the formation of an in situ iron oxyhydroxide silicate coating and a significant reduction in pyrite oxidation, which was minimized by addition of sodium carbonate.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/32915
Date31 August 2012
CreatorsPeters, Samuel
ContributorsPapangelakis, Vladimiros G.
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
Languageen_ca
Detected LanguageEnglish
TypeThesis

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