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Cobalt recovery from mixed Co–Mn hydroxide precipitates by ammonia–ammonium carbonate leaching / A. Katsiapi in Minerals engineering, Vol. 23 N° 8 (Juillet 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 8 (Juillet 2010) . - pp. 643–651 Titre : Cobalt recovery from mixed Co–Mn hydroxide precipitates by ammonia–ammonium carbonate leaching Type de document : texte imprimé Auteurs : A. Katsiapi, Auteur ; P.E. Tsakiridis, Auteur ; P. Oustadakis, Auteur Année de publication : 2011 Article en page(s) : pp. 643–651 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Cobalt  Manganese  Precipitation  Ammoniacal  leaching Résumé : The research work presented in this paper focused on the recovery of cobalt from mixed Co–Mn hydroxide precipitates (obtained from sulphate leach liquors of nickel oxide ore), using ammonia–ammonium carbonate leaching. The characterization of the initial mixed hydroxide precipitates, as well as the corresponding leached residue was carried out by X-ray Diffraction, TG–DTA and Scanning Electron Microscopy. Cobalt and manganese precipitation was based on the statistical design and analysis of experiments, in order to determine the main effects and interactions of the precipitation factors, which were the equilibrium pH and the temperature. Co and Mn were precipitated as hydroxides at pH = 10.5 and T = 25 °C, using 5 M NaOH as a neutralizing agent, by 99.9% and 99.5%, respectively. The main mineralogical phases were, Mn3O4 (Hausmannite), γ-Mn3O4 and CoMn2O4, while Co(OH)2 and Mn(OH)2 (Pyrochroite) were also present as minor constituents. Cobalt and manganese separation was based on selective cobalt recovery by ammonia–ammonium carbonate leaching of the produced mixed hydroxide precipitate. The factors studied were the ammonia–ammonium carbonate concentration and the solid to liquid ratio. The cobalt recovery efficiency reached 93%. Mn3O4 (Hausmannite) was the main mineralogical phase of the leached residue, while MnCO3 (Rhodochrosite) and Mn2O3 were also present. Small quantities of cobalt were also observed in the residue as CoMn2O4. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000622 [article] Cobalt recovery from mixed Co–Mn hydroxide precipitates by ammonia–ammonium carbonate leaching [texte imprimé] / A. Katsiapi, Auteur ; P.E. Tsakiridis, Auteur ; P. Oustadakis, Auteur . - 2011 . - pp. 643–651. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 8 (Juillet 2010) . - pp. 643–651 Mots-clés : Cobalt  Manganese  Precipitation  Ammoniacal  leaching Résumé : The research work presented in this paper focused on the recovery of cobalt from mixed Co–Mn hydroxide precipitates (obtained from sulphate leach liquors of nickel oxide ore), using ammonia–ammonium carbonate leaching. The characterization of the initial mixed hydroxide precipitates, as well as the corresponding leached residue was carried out by X-ray Diffraction, TG–DTA and Scanning Electron Microscopy. Cobalt and manganese precipitation was based on the statistical design and analysis of experiments, in order to determine the main effects and interactions of the precipitation factors, which were the equilibrium pH and the temperature. Co and Mn were precipitated as hydroxides at pH = 10.5 and T = 25 °C, using 5 M NaOH as a neutralizing agent, by 99.9% and 99.5%, respectively. The main mineralogical phases were, Mn3O4 (Hausmannite), γ-Mn3O4 and CoMn2O4, while Co(OH)2 and Mn(OH)2 (Pyrochroite) were also present as minor constituents. Cobalt and manganese separation was based on selective cobalt recovery by ammonia–ammonium carbonate leaching of the produced mixed hydroxide precipitate. The factors studied were the ammonia–ammonium carbonate concentration and the solid to liquid ratio. The cobalt recovery efficiency reached 93%. Mn3O4 (Hausmannite) was the main mineralogical phase of the leached residue, while MnCO3 (Rhodochrosite) and Mn2O3 were also present. Small quantities of cobalt were also observed in the residue as CoMn2O4. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000622

Hydrometallurgical process for the separation and recovery of nickel from sulphate heap leach liquor of nickeliferrous laterite ores / S. Agatzini-Leonardou in Minerals engineering, Vol. 22 N° 14 (Novembre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 14 (Novembre 2009) . - pp. 1181–1192 Titre : Hydrometallurgical process for the separation and recovery of nickel from sulphate heap leach liquor of nickeliferrous laterite ores Type de document : texte imprimé Auteurs : S. Agatzini-Leonardou, Auteur ; P.E. Tsakiridis, Auteur ; P. Oustadakis, Auteur Année de publication : 2009 Article en page(s) : pp. 1181–1192 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Laterite  leach  liquor  Hydrometallurgical  process  Nickel  recovery Résumé : The Laboratory of Metallurgy of the National Technical University of Athens has developed and patented a novel integrated hydrometallurgical method, suitable to treat low-grade nickel oxide ores efficiently and economically. It involves heap leaching of the ore by dilute sulphuric acid at ambient temperature, purification of the leach liquor and recovery of nickel and cobalt by electrowinning. A typical composition of the pregnant solution produced from heap leaching is the following: Ni2+ = 5 g/L, Co2+ = 0.3 g/L, Fe3+ = 23.0 g/L, Al3+ = 6.0 g/L, Cr3+ = 1.0 g/L, Mn2+ = 1 g/L and Mg2+ = 8 g/L. The proposed hydrometallurgical process for nickel recovery from real sulphate heap leach liquors consists of the following six (6) unit operations: (1)Removal of iron, aluminium and chromium, as easily filterable crystalline basic sulphate salts of the jarosite–alunite type, at atmospheric pressure, by chemical precipitation at pH: 3.5 and 95 °C. (2)Cobalt, manganese and magnesium extraction over nickel by Cyanex 272 at pH: 5.5, T: 40 °C, with 20% extractant concentration and stripping of the loaded organic phase at T: 40 °C with diluted H2SO4 (4 M). (3)Nickel concentration by solvent extraction using Cyanex 272 at pH: 7.5, T: 40 °C, with 10% extractant concentration and stripping of the loaded organic phase by nickel spent electrolyte (55.45 g/L Ni) at T: 40 °C with diluted H2SO4 (2 M). (4)Nickel electrowinning from sulphate solutions, using stainless steel as cathode and Pb–8%Sb as anode. The pH of the electrolyte (10 g/L H3BO3, 75.95 g/L Ni2+ and 130 g/L Na2SO4) was adjusted at 3.5 and at 60 °C, while the current density was kept constant at 20 mA/cm2. (5)Cobalt and manganese extraction over magnesium by Cyanex 302 at pH: (5.0), T: 40 °C, with 20% extractant concentration and stripping of the loaded organic phase at T: 40 °C with diluted H2SO4 (1 M). (6)Removal of magnesium by chemical precipitation (as brucite), using Ca(OH)2 as neutralizing agent, at atmospheric pressure, pH = 10 and 25 °C. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001514 [article] Hydrometallurgical process for the separation and recovery of nickel from sulphate heap leach liquor of nickeliferrous laterite ores [texte imprimé] / S. Agatzini-Leonardou, Auteur ; P.E. Tsakiridis, Auteur ; P. Oustadakis, Auteur . - 2009 . - pp. 1181–1192. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 14 (Novembre 2009) . - pp. 1181–1192 Mots-clés : Laterite  leach  liquor  Hydrometallurgical  process  Nickel  recovery Résumé : The Laboratory of Metallurgy of the National Technical University of Athens has developed and patented a novel integrated hydrometallurgical method, suitable to treat low-grade nickel oxide ores efficiently and economically. It involves heap leaching of the ore by dilute sulphuric acid at ambient temperature, purification of the leach liquor and recovery of nickel and cobalt by electrowinning. A typical composition of the pregnant solution produced from heap leaching is the following: Ni2+ = 5 g/L, Co2+ = 0.3 g/L, Fe3+ = 23.0 g/L, Al3+ = 6.0 g/L, Cr3+ = 1.0 g/L, Mn2+ = 1 g/L and Mg2+ = 8 g/L. The proposed hydrometallurgical process for nickel recovery from real sulphate heap leach liquors consists of the following six (6) unit operations: (1)Removal of iron, aluminium and chromium, as easily filterable crystalline basic sulphate salts of the jarosite–alunite type, at atmospheric pressure, by chemical precipitation at pH: 3.5 and 95 °C. (2)Cobalt, manganese and magnesium extraction over nickel by Cyanex 272 at pH: 5.5, T: 40 °C, with 20% extractant concentration and stripping of the loaded organic phase at T: 40 °C with diluted H2SO4 (4 M). (3)Nickel concentration by solvent extraction using Cyanex 272 at pH: 7.5, T: 40 °C, with 10% extractant concentration and stripping of the loaded organic phase by nickel spent electrolyte (55.45 g/L Ni) at T: 40 °C with diluted H2SO4 (2 M). (4)Nickel electrowinning from sulphate solutions, using stainless steel as cathode and Pb–8%Sb as anode. The pH of the electrolyte (10 g/L H3BO3, 75.95 g/L Ni2+ and 130 g/L Na2SO4) was adjusted at 3.5 and at 60 °C, while the current density was kept constant at 20 mA/cm2. (5)Cobalt and manganese extraction over magnesium by Cyanex 302 at pH: (5.0), T: 40 °C, with 20% extractant concentration and stripping of the loaded organic phase at T: 40 °C with diluted H2SO4 (1 M). (6)Removal of magnesium by chemical precipitation (as brucite), using Ca(OH)2 as neutralizing agent, at atmospheric pressure, pH = 10 and 25 °C. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001514