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CO2 Sequestration in chrysotile mining residues — implication of watering and passivation under environmental conditions / Gnouyaro P. Assima in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp 8726–8734 Titre : CO2 Sequestration in chrysotile mining residues — implication of watering and passivation under environmental conditions Type de document : texte imprimé Auteurs : Gnouyaro P. Assima, Auteur ; Faïçal Larachi, Auteur ; Georges Beaudoin, Auteur Année de publication : 2012 Article en page(s) : pp 8726–8734 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Chrysotile  Mining  Residues Résumé : Factors affecting carbon dioxide fixation in chrysotile mining residues (CMR) under environmental conditions were studied by reproducing mineral dissolution and carbonation in laboratory columns packed with CMR particles. Carbonation is very sensitive to water saturation and watering frequency of the CMR porous media. CO2 uptake by dry residues subjected to dry CO2 flow for several days at ambient temperature was below 0.02%. However, an increase by a factor of 20 in CO2 uptake was achieved by periodic addition of small amounts of water with respect to a moistened CO2 stream over dry CMR samples. The highest MgCO3 conversion resulted in nearly 22 mg of CO2 captured per gram of residue, revealing that up to 93% of Mg remained noncarbonated because of surface obstructing processes. Magnesium leaching from CMR was hindered by two concomitant passivation phenomena limiting the residue’s CO2 storage capacity. A unique cyclic voltammetry technique using oxic and anoxic aqueous solutions contacted with CMR fixed beds was implemented to assess the relative importance from CMR-borne iron electrochemical passivation and silica-deposit nonelectrochemical passivation. Passivation around the dissolving CMR particles by iron hydroxide precipitation was found to develop very rapidly in comparison to silica gel polymerization. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202693q [article] CO2 Sequestration in chrysotile mining residues — implication of watering and passivation under environmental conditions [texte imprimé] / Gnouyaro P. Assima, Auteur ; Faïçal Larachi, Auteur ; Georges Beaudoin, Auteur . - 2012 . - pp 8726–8734. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp 8726–8734 Mots-clés : Chrysotile  Mining  Residues Résumé : Factors affecting carbon dioxide fixation in chrysotile mining residues (CMR) under environmental conditions were studied by reproducing mineral dissolution and carbonation in laboratory columns packed with CMR particles. Carbonation is very sensitive to water saturation and watering frequency of the CMR porous media. CO2 uptake by dry residues subjected to dry CO2 flow for several days at ambient temperature was below 0.02%. However, an increase by a factor of 20 in CO2 uptake was achieved by periodic addition of small amounts of water with respect to a moistened CO2 stream over dry CMR samples. The highest MgCO3 conversion resulted in nearly 22 mg of CO2 captured per gram of residue, revealing that up to 93% of Mg remained noncarbonated because of surface obstructing processes. Magnesium leaching from CMR was hindered by two concomitant passivation phenomena limiting the residue’s CO2 storage capacity. A unique cyclic voltammetry technique using oxic and anoxic aqueous solutions contacted with CMR fixed beds was implemented to assess the relative importance from CMR-borne iron electrochemical passivation and silica-deposit nonelectrochemical passivation. Passivation around the dissolving CMR particles by iron hydroxide precipitation was found to develop very rapidly in comparison to silica gel polymerization. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie202693q

Geochemistry and metallogeny of Ag-Pb-Zn veins in the purcell basin, British Columbia / Jean-Philippe Paiement in Economic geology, Vol. 107 N° 6 (Septembre/Octobre 2012) 

Public ISBD [article]  in Economic geology > Vol. 107 N° 6 (Septembre/Octobre 2012) . - pp. 1303-1320 Titre : Geochemistry and metallogeny of Ag-Pb-Zn veins in the purcell basin, British Columbia Type de document : texte imprimé Auteurs : Jean-Philippe Paiement, Auteur ; Georges Beaudoin, Auteur ; Suzanne Paradis, Auteur Année de publication : 2012 Article en page(s) : pp. 1303-1320 Note générale : Economic geology Langues : Anglais (eng) Mots-clés : Ag-Pb-Zn  veins;  Metallogeny;  Geochemistry;  British  Columbia Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : The Mesoproterozoic Purcell Basin in Canada contains three different types of veins: (1) type 1 Pb-Zn-Ag veins are composed of Fe-rich sphalerite, pyrrhotite, galena, freibergite, and pyrite with minor quartz gangue; (2) type 2 Pb-Ag-Cu-Au veins are characterized by galena, pyrite, freibergite, and gold in a quartz gangue; and (3) type 3 Ag-Pb-Zn vein and replacement deposits contain Fe-poor sphalerite, galena, pyrite, and freibergite in a quartz-dolomite gangue that locally replaces host dolostone. The sulfur isotope composition of type 1, 2, and 3 vein and replacement deposits closely reflects their respective stratigraphic positions. Type 1 and 2 veins hosted in lower Purcell sedimentary rocks have light sulfur isotope compositions (−4.8 to +2.5‰) similar to diagenic pyrite disseminated in clastic sedimentary host rocks. Type 3 veins and the replacement deposits hosted in upper Purcell Supergroup rocks have heavy sulfur isotope compositions (8.3–17.2‰) indicative of thermo-chemical reduction of marine sulfate in carbonate host rocks. Quartz from type 1 Pb-Zn-Ag veins has δ18OSMOW values ranging from 7 to 17‰, whereas type 2 and 3 vein and replacement deposits have δ18O values ranging from 9 to 20‰. The range of δ18O values for type 1, 2, and 3 veins is the result of mixing of metamorphic fluids with a δ18O value higher than 11.5‰ and an upper crustal fluid with a δ18O lower than 1.2‰, in equilibrium with the host rocks during Proterozoic (type 1) and Mesozoic-Cenozoic (type 2 and 3) hydrothermal events. Galena and freibergite lead isotope compositions plot in two groups, consistent with previous studies. Type 1 Pb-Zn-Ag veins have a nonradiogenic lead signature (206Pb/204Pb: 16.322–16.435) and are considered Proterozoic in age. Type 2 Pb-Ag-Au-Cu veins and type 3 Ag-Pb-Zn vein and replacement deposits have a radiogenic lead signature (206Pb/204Pb: 17.842–19.347) and are interpreted to be Mesozoic-Cenozoic in age. Hydrothermal sericite from the type 3 Ptarmigan replacement deposit yields a 40Ar/39Ar age of 133.1 ± 0.7 Ma, indicating a Cretaceous age for type 3 deposits. Type 1 veins are interpreted to be the result of hydrothermal fluids generated during the Proterozoic East Kootenay Orogeny, whereas type 2 and 3 veins and replacement deposits are interpreted to be the result of Late Cretaceous-Paleocene tectonism. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/107/6/1303.short [article] Geochemistry and metallogeny of Ag-Pb-Zn veins in the purcell basin, British Columbia [texte imprimé] / Jean-Philippe Paiement, Auteur ; Georges Beaudoin, Auteur ; Suzanne Paradis, Auteur . - 2012 . - pp. 1303-1320. Economic geology Langues : Anglais (eng) in Economic geology > Vol. 107 N° 6 (Septembre/Octobre 2012) . - pp. 1303-1320 Mots-clés : Ag-Pb-Zn  veins;  Metallogeny;  Geochemistry;  British  Columbia Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : The Mesoproterozoic Purcell Basin in Canada contains three different types of veins: (1) type 1 Pb-Zn-Ag veins are composed of Fe-rich sphalerite, pyrrhotite, galena, freibergite, and pyrite with minor quartz gangue; (2) type 2 Pb-Ag-Cu-Au veins are characterized by galena, pyrite, freibergite, and gold in a quartz gangue; and (3) type 3 Ag-Pb-Zn vein and replacement deposits contain Fe-poor sphalerite, galena, pyrite, and freibergite in a quartz-dolomite gangue that locally replaces host dolostone. The sulfur isotope composition of type 1, 2, and 3 vein and replacement deposits closely reflects their respective stratigraphic positions. Type 1 and 2 veins hosted in lower Purcell sedimentary rocks have light sulfur isotope compositions (−4.8 to +2.5‰) similar to diagenic pyrite disseminated in clastic sedimentary host rocks. Type 3 veins and the replacement deposits hosted in upper Purcell Supergroup rocks have heavy sulfur isotope compositions (8.3–17.2‰) indicative of thermo-chemical reduction of marine sulfate in carbonate host rocks. Quartz from type 1 Pb-Zn-Ag veins has δ18OSMOW values ranging from 7 to 17‰, whereas type 2 and 3 vein and replacement deposits have δ18O values ranging from 9 to 20‰. The range of δ18O values for type 1, 2, and 3 veins is the result of mixing of metamorphic fluids with a δ18O value higher than 11.5‰ and an upper crustal fluid with a δ18O lower than 1.2‰, in equilibrium with the host rocks during Proterozoic (type 1) and Mesozoic-Cenozoic (type 2 and 3) hydrothermal events. Galena and freibergite lead isotope compositions plot in two groups, consistent with previous studies. Type 1 Pb-Zn-Ag veins have a nonradiogenic lead signature (206Pb/204Pb: 16.322–16.435) and are considered Proterozoic in age. Type 2 Pb-Ag-Au-Cu veins and type 3 Ag-Pb-Zn vein and replacement deposits have a radiogenic lead signature (206Pb/204Pb: 17.842–19.347) and are interpreted to be Mesozoic-Cenozoic in age. Hydrothermal sericite from the type 3 Ptarmigan replacement deposit yields a 40Ar/39Ar age of 133.1 ± 0.7 Ma, indicating a Cretaceous age for type 3 deposits. Type 1 veins are interpreted to be the result of hydrothermal fluids generated during the Proterozoic East Kootenay Orogeny, whereas type 2 and 3 veins and replacement deposits are interpreted to be the result of Late Cretaceous-Paleocene tectonism. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/107/6/1303.short