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The effect of iron contaminants on thiosulphate leaching of gold / D. Feng in Minerals engineering, Vol. 23 N° 5 (Avril 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 5 (Avril 2010) . - pp. 399–406 Titre : The effect of iron contaminants on thiosulphate leaching of gold Type de document : texte imprimé Auteurs : D. Feng, Auteur ; J. S. J. van Deventer, Auteur Année de publication : 2011 Article en page(s) : pp. 399–406 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Gold  ores  Sulphide  ores  Grinding  Leaching  Surface  modification Résumé : Metallic iron and ferric ions were subjected to wet grinding with a sulphide ore in a ceramic ball mill to simulate the fine grinding process using mild steel, in an attempt to investigate the effect of iron species on the ammoniacal thiosulphate leaching of gold. Metallic iron and ferric ions decreased gold leaching in both kinetics and overall extraction when they were added in the wet grinding of a sulphide ore. This detrimental effect became more pronounced with the addition of metallic iron and ferric ions at higher concentrations. Metallic iron retarded the gold leaching more than ferric ions at the same dosage. The decomposition of thiosulphate in the leaching of the sulphide ore increased with the addition of metallic iron and ferric ions in the wet grinding. Thermodynamic analysis indicated that the predominant species for iron was ferric hydroxide under the leaching conditions. Wet grinding at a higher pH of 9 and use of ethylenediaminetetraacetic acid (EDTA) were ineffective in improving the gold leaching with the addition of metallic ions and ferric ions in the wet grinding. Iron oxide and hydroxide slime coatings at the surfaces of pyrite and pyrrhotite were reduced using carboxymethyl cellulose (CMC) to render the sulphide and slime particle surfaces highly negatively charged. Precipitation of iron oxide species at the surfaces of pyrite and pyrrhotite was observed in the morphological study of the leach residues with the addition of metallic iron in the wet grinding. The addition of CMC effectively reduced iron oxide slime coating at the sulphide surfaces and the aggregation of fine particles. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509002945 [article] The effect of iron contaminants on thiosulphate leaching of gold [texte imprimé] / D. Feng, Auteur ; J. S. J. van Deventer, Auteur . - 2011 . - pp. 399–406. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 5 (Avril 2010) . - pp. 399–406 Mots-clés : Gold  ores  Sulphide  ores  Grinding  Leaching  Surface  modification Résumé : Metallic iron and ferric ions were subjected to wet grinding with a sulphide ore in a ceramic ball mill to simulate the fine grinding process using mild steel, in an attempt to investigate the effect of iron species on the ammoniacal thiosulphate leaching of gold. Metallic iron and ferric ions decreased gold leaching in both kinetics and overall extraction when they were added in the wet grinding of a sulphide ore. This detrimental effect became more pronounced with the addition of metallic iron and ferric ions at higher concentrations. Metallic iron retarded the gold leaching more than ferric ions at the same dosage. The decomposition of thiosulphate in the leaching of the sulphide ore increased with the addition of metallic iron and ferric ions in the wet grinding. Thermodynamic analysis indicated that the predominant species for iron was ferric hydroxide under the leaching conditions. Wet grinding at a higher pH of 9 and use of ethylenediaminetetraacetic acid (EDTA) were ineffective in improving the gold leaching with the addition of metallic ions and ferric ions in the wet grinding. Iron oxide and hydroxide slime coatings at the surfaces of pyrite and pyrrhotite were reduced using carboxymethyl cellulose (CMC) to render the sulphide and slime particle surfaces highly negatively charged. Precipitation of iron oxide species at the surfaces of pyrite and pyrrhotite was observed in the morphological study of the leach residues with the addition of metallic iron in the wet grinding. The addition of CMC effectively reduced iron oxide slime coating at the sulphide surfaces and the aggregation of fine particles. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509002945

Thiosulphate leaching of gold in the presence of ethylenediaminetetraacetic acid (EDTA) / D. Feng in Minerals engineering, Vol. 23 N° 2 (Janvier 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 2 (Janvier 2010) . - pp. 143-150 Titre : Thiosulphate leaching of gold in the presence of ethylenediaminetetraacetic acid (EDTA) Type de document : texte imprimé Auteurs : D. Feng, Auteur ; J. S. J. van Deventer, Auteur Article en page(s) : pp. 143-150 Note générale : Génie Minier Métallurgie Langues : Anglais (eng) Mots-clés : Gold  ores  Sulphide  ores  Grinding  Leaching  Surface  modification Index. décimale : 622 Industrie minière Résumé : The addition of low levels of ethylenediaminetetraacetic acid (EDTA) in the ammoniacal thiosulphate gold leach system lowered the catalytic cupric/cuprous redox equilibrium potential, hence the mixed solution potential and reduced the consumption of thiosulphate. In the leaching of pure gold, gold dissolution was enhanced in the presence of EDTA at a relatively low concentration, but excessive EDTA decreased gold dissolution. Raman analysis of the leached gold foil indicated that the stabilisation of thiosulphate by EDTA decreased the formation of the passivation layers of elemental sulphur and copper sulphide at the gold surface. In the leaching of a sulphide ore, the leaching kinetics and overall extractions of gold and silver were enhanced substantially, while the consumption of ammonium thiosulphate was reduced from 9.63 kg/t to 3.85 kg/t in the presence of 2.0 mM EDTA after 24 h leaching. This beneficial effect became more pronounced at a higher EDTA concentration. The enhanced gold and silver extractions by EDTA were attributed to the increase in the dissolution of gold and silver bearing sulphides, the stabilisation of copper and thiosulphate in leach solutions, the prevention of leaching passivation and the decrease in the interference of foreign heavy metal ions. The use of EDTA in the ammoniacal thiosulphate leaching system makes it practical to achieve satisfactory gold extraction over extended periods of leaching under low reagent concentrations, where the consumption of thiosulphate is low. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VDR-4XDKC9K-1&_user=6 [...] [article] Thiosulphate leaching of gold in the presence of ethylenediaminetetraacetic acid (EDTA) [texte imprimé] / D. Feng, Auteur ; J. S. J. van Deventer, Auteur . - pp. 143-150. Génie Minier Métallurgie Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 2 (Janvier 2010) . - pp. 143-150 Mots-clés : Gold  ores  Sulphide  ores  Grinding  Leaching  Surface  modification Index. décimale : 622 Industrie minière Résumé : The addition of low levels of ethylenediaminetetraacetic acid (EDTA) in the ammoniacal thiosulphate gold leach system lowered the catalytic cupric/cuprous redox equilibrium potential, hence the mixed solution potential and reduced the consumption of thiosulphate. In the leaching of pure gold, gold dissolution was enhanced in the presence of EDTA at a relatively low concentration, but excessive EDTA decreased gold dissolution. Raman analysis of the leached gold foil indicated that the stabilisation of thiosulphate by EDTA decreased the formation of the passivation layers of elemental sulphur and copper sulphide at the gold surface. In the leaching of a sulphide ore, the leaching kinetics and overall extractions of gold and silver were enhanced substantially, while the consumption of ammonium thiosulphate was reduced from 9.63 kg/t to 3.85 kg/t in the presence of 2.0 mM EDTA after 24 h leaching. This beneficial effect became more pronounced at a higher EDTA concentration. The enhanced gold and silver extractions by EDTA were attributed to the increase in the dissolution of gold and silver bearing sulphides, the stabilisation of copper and thiosulphate in leach solutions, the prevention of leaching passivation and the decrease in the interference of foreign heavy metal ions. The use of EDTA in the ammoniacal thiosulphate leaching system makes it practical to achieve satisfactory gold extraction over extended periods of leaching under low reagent concentrations, where the consumption of thiosulphate is low. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VDR-4XDKC9K-1&_user=6 [...]