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Mechanisms of sulfide ion oxidation during cyanidation / D.M. Hewitt in Minerals engineering, Vol. 22 N° 13 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 13 (Octobre 2009) . - pp. 1166–1172 Titre : Mechanisms of sulfide ion oxidation during cyanidation : Part II: Surface catalysis by pyrite Type de document : texte imprimé Auteurs : D.M. Hewitt, Auteur ; P. L. Breuer, Auteur ; M.I. Jeffrey, Auteur Année de publication : 2009 Article en page(s) : pp. 1166–1172 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Cyanidation  Sulfide  ores Résumé : The mechanisms and the reaction products for the oxidation of sulfide ions in the presence of pyrite have been established. When the leach solution contains free sulfide ions, oxidation occurs via electron transfer from the sulfide ion to dissolved oxygen on the pyrite mineral surface, with polysulfides being formed as an intermediate oxidation product. In the absence of cyanide, the polysulfides are further oxidised to thiosulfate, whilst with cyanide present, thiocyanate and sulfite are also formed from the reaction of polysulfides with cyanide and dissolved oxygen. Polysulfide chain length has been shown to affect the final reaction products of polysulfide oxidation by dissolved oxygen. The rate of pyrite catalysed sulfide ion oxidation was found to be slower in cyanide solutions compared to cyanide free solutions. Mixed potential measurements indicated that the reduction of oxygen at the pyrite surface is hindered in the presence of cyanide. The presence of sulfide ions was also found to activate the pyrite surface, increasing its rate of oxidation by oxygen. This effect was particularly evident in the presence of cyanide; in the presence of sulfide the increase in total sulfur from pyrite oxidation was 2.3 mM in 7 h, compared to an increase of <1 mM in the absence of sulfide over 24 h. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001472 [article] Mechanisms of sulfide ion oxidation during cyanidation : Part II: Surface catalysis by pyrite [texte imprimé] / D.M. Hewitt, Auteur ; P. L. Breuer, Auteur ; M.I. Jeffrey, Auteur . - 2009 . - pp. 1166–1172. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 13 (Octobre 2009) . - pp. 1166–1172 Mots-clés : Cyanidation  Sulfide  ores Résumé : The mechanisms and the reaction products for the oxidation of sulfide ions in the presence of pyrite have been established. When the leach solution contains free sulfide ions, oxidation occurs via electron transfer from the sulfide ion to dissolved oxygen on the pyrite mineral surface, with polysulfides being formed as an intermediate oxidation product. In the absence of cyanide, the polysulfides are further oxidised to thiosulfate, whilst with cyanide present, thiocyanate and sulfite are also formed from the reaction of polysulfides with cyanide and dissolved oxygen. Polysulfide chain length has been shown to affect the final reaction products of polysulfide oxidation by dissolved oxygen. The rate of pyrite catalysed sulfide ion oxidation was found to be slower in cyanide solutions compared to cyanide free solutions. Mixed potential measurements indicated that the reduction of oxygen at the pyrite surface is hindered in the presence of cyanide. The presence of sulfide ions was also found to activate the pyrite surface, increasing its rate of oxidation by oxygen. This effect was particularly evident in the presence of cyanide; in the presence of sulfide the increase in total sulfur from pyrite oxidation was 2.3 mM in 7 h, compared to an increase of <1 mM in the absence of sulfide over 24 h. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001472