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Kinetics of saprolitic laterite leaching by sulphuric acid at atmospheric pressure / Wei Luo in Minerals engineering, Vol. 23 N° 6 (Mai 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 6 (Mai 2010) . - pp. 458–462 Titre : Kinetics of saprolitic laterite leaching by sulphuric acid at atmospheric pressure Type de document : texte imprimé Auteurs : Wei Luo, Auteur ; Qiming Feng, Auteur ; Leming Ou, Auteur Année de publication : 2011 Article en page(s) : pp. 458–462 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Oxide  ores  Ore  mineralogy  Leaching  Reaction  kinetics Résumé : Mineralogical analyses of the saprolitic laterite material have been characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal analysis, scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the saprolitic laterite material consists mainly of nickel-substituted lizardite showing the pebble-like morphology and traces of magnetite and phlogopite. Leaching results showed that as much as 84.8% nickel could be leached under the experimental conditions of 10% (v/v) H2SO4, 90 °C reaction temperature, leached within 5 min, particle size d50 = 25 μm, stirring at 500 rpm and liquid to solid ratio 3:1. The kinetics of nickel and magnesium leaching from the saprolitic laterite material have been investigated in a mechanically stirred reactor and the activation energies were determined to be 53.9 kJ mol−1 for nickel and 59.4 kJ mol−1 for magnesium respectively, which are characteristic for a chemical reaction controlled process. The similarity of the activation energies of nickel and magnesium leaching from the saprolitic laterite material by sulphuric acid means that nickel in lizardite is loosely bound within the octahedral layer and almost all of the nickel could be leached simultaneously with magnesium but without complete decomposition of the silicate structure. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268750900260X [article] Kinetics of saprolitic laterite leaching by sulphuric acid at atmospheric pressure [texte imprimé] / Wei Luo, Auteur ; Qiming Feng, Auteur ; Leming Ou, Auteur . - 2011 . - pp. 458–462. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 6 (Mai 2010) . - pp. 458–462 Mots-clés : Oxide  ores  Ore  mineralogy  Leaching  Reaction  kinetics Résumé : Mineralogical analyses of the saprolitic laterite material have been characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal analysis, scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the saprolitic laterite material consists mainly of nickel-substituted lizardite showing the pebble-like morphology and traces of magnetite and phlogopite. Leaching results showed that as much as 84.8% nickel could be leached under the experimental conditions of 10% (v/v) H2SO4, 90 °C reaction temperature, leached within 5 min, particle size d50 = 25 μm, stirring at 500 rpm and liquid to solid ratio 3:1. The kinetics of nickel and magnesium leaching from the saprolitic laterite material have been investigated in a mechanically stirred reactor and the activation energies were determined to be 53.9 kJ mol−1 for nickel and 59.4 kJ mol−1 for magnesium respectively, which are characteristic for a chemical reaction controlled process. The similarity of the activation energies of nickel and magnesium leaching from the saprolitic laterite material by sulphuric acid means that nickel in lizardite is loosely bound within the octahedral layer and almost all of the nickel could be leached simultaneously with magnesium but without complete decomposition of the silicate structure. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268750900260X

Solution chemistry of sodium silicate and implications for pyrite flotation / Bo Feng in Industrial & engineering chemistry research, Vol. 51 N° 37 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 37 (Septembre 2012) . - pp. 12089–12094 Titre : Solution chemistry of sodium silicate and implications for pyrite flotation Type de document : texte imprimé Auteurs : Bo Feng, Auteur ; Yiping Lu, Auteur ; Qiming Feng, Auteur Année de publication : 2012 Article en page(s) : pp. 12089–12094 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Solution  chemistry Résumé : The solution chemistry of sodium silicate and implications for pyrite flotation have been studied. In addition to flotation and sedimentation tests, electrophoresis, inductively coupled plasma (ICP) tests, and X-ray photoelectron spectroscopy (XPS) have been used. The flotation and sedimentation results show that lizardite causes problems in the flotation of pyrite by adhering to the pyrite particles. Addition of the sodium silicate could make the mixed sample of pyrite and lizardite more disperse in the alkaline condition and significantly reduce the adverse effect of lizardite on the flotation of pyrite. ICP tests and XPS analysises show that sodium silicate can adsorb onto the lizardite surface and change the surface characteristic of lizardite. Sodium silicate mainly exists in the form of SiO(OH)3– in the pH range that sodium silicate can restore pyrite flotation recovery. The adsorption of SiO(OH)3– ions at the lizardite/solution interface overcompensates the positive charge on the lizardite particle and its ζ potential is rendered negative. The total interaction energy between lizardite and pyrite is changed from attractive energy to repulsive energy in the presence of sodium silicate, according to the calculation of the Derjaguin–Landau–Verwey–Overbeek theory. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301307a [article] Solution chemistry of sodium silicate and implications for pyrite flotation [texte imprimé] / Bo Feng, Auteur ; Yiping Lu, Auteur ; Qiming Feng, Auteur . - 2012 . - pp. 12089–12094. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 37 (Septembre 2012) . - pp. 12089–12094 Mots-clés : Solution  chemistry Résumé : The solution chemistry of sodium silicate and implications for pyrite flotation have been studied. In addition to flotation and sedimentation tests, electrophoresis, inductively coupled plasma (ICP) tests, and X-ray photoelectron spectroscopy (XPS) have been used. The flotation and sedimentation results show that lizardite causes problems in the flotation of pyrite by adhering to the pyrite particles. Addition of the sodium silicate could make the mixed sample of pyrite and lizardite more disperse in the alkaline condition and significantly reduce the adverse effect of lizardite on the flotation of pyrite. ICP tests and XPS analysises show that sodium silicate can adsorb onto the lizardite surface and change the surface characteristic of lizardite. Sodium silicate mainly exists in the form of SiO(OH)3– in the pH range that sodium silicate can restore pyrite flotation recovery. The adsorption of SiO(OH)3– ions at the lizardite/solution interface overcompensates the positive charge on the lizardite particle and its ζ potential is rendered negative. The total interaction energy between lizardite and pyrite is changed from attractive energy to repulsive energy in the presence of sodium silicate, according to the calculation of the Derjaguin–Landau–Verwey–Overbeek theory. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301307a