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dc.contributor.authorXia, Chenen
dc.date2008-09-18 11:48:38.672
dc.date.accessioned2010-04-01T17:45:05Z
dc.date.available2010-04-01T17:45:05Z
dc.date.issued2010-04-01T17:45:05Z
dc.identifier.urihttp://hdl.handle.net/1974/5465
dc.descriptionThesis (Ph.D, Mining Engineering) -- Queen's University, 2008-09-18 11:48:38.672en
dc.description.abstractThe effects of some associated minerals on thiosulfate gold leaching were studied through thermodynamic analysis and leaching experiments on composite ore samples containing various minerals and a reference silicate gold ore. In the leaching test on the reference gold ore, about 93% of gold was extracted within 3.0 hours. The presence of various amount of pyrite, pyrrhotite, chalcopyrite, arsenopyrite, chalcocite, bornite, and some lead species, has significant detrimental effects. Under reduced oxygen conditions, the thiosulfate consumptions could be significantly reduced. High gold extractions (i.e. >= 90%) were observed in the leaching tests with reduced dissolved oxygen (i.e., 0.7% oxygen in the supplied gas) in the absence or in the presence of sulfide minerals such as pyrite, pyrrhotite, arsenopyrite and chalcopyrite. High copper concentration and a pre-aeration step was also found to largely increase the gold extractions under such conditions. Thiosulfate-copper-ethylenediamine system was found effective in the leaching of gold. The leaching kinetics was significantly slower than that of the conventional thiosulfate-copper-ammonia leaching. The consumption of thiosulfate, however, was largely reduced. This leaching system worked effectively on the reference gold ore within a wider pH range (e.g., 6-11), with or without ammonia. The presence of ammonia in a low concentration improved the leaching rate but also increase the consumption of thiosulfate. Comparable gold extractions were observed in the leaching of the composite ores containing various sulfide minerals, such as pyrite, pyrrhotite, chalcocite, galena and chalcopyrite. The leaching of gold in the presence of iron sulfides was also improved by applying chemical additives, such as, carbonate, calcium, galena, phosphate, and additional hydroxide anion. It is proposed that these additives either passivated the harmful surface of sulfide minerals or masked some detrimental aqueous species. Finally, some improved leaching methods concluded in this study were applied on a few industrial ore samples in order to demonstrate the effectiveness of these methods. It was found that by comprehensively applying these improved thiosulfate leaching strategies, satisfactory gold extractions and thiosulfate consumption results were archived on these ores.en
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectThiosulfateen
dc.subjectGolden
dc.subjectAmmoniaen
dc.subjectCopperen
dc.subjectEthylenediamineen
dc.subjectPhosphateen
dc.subjectPyriteen
dc.subjectPyrrhotiteen
dc.subjectArsenopyriteen
dc.subjectChalcopyriteen
dc.subjectChalcociteen
dc.subjectBorniteen
dc.subjectGalenaen
dc.subjectLeaden
dc.subjectEh-pHen
dc.subjectOxygenen
dc.subjectExtractionen
dc.subjectLeachingen
dc.subjectPre-aerationen
dc.subjectPassivationen
dc.titleAssociated Sulfide Minerals in Thiosulfate Leaching of Gold: Problems and Solutionsen
dc.typethesisen
dc.description.restricted-thesis6 monthsen
dc.description.degreePhDen
dc.contributor.supervisorYen, Wan-Taien
dc.contributor.departmentMining Engineeringen
dc.degree.grantorQueen's University at Kingstonen


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