Documents disponibles écrits par cet auteur

Coupling oxidation to transient drying during multilayer deposition of thickened gold tailings / Rachel Bryan in Minerals engineering, Vol. 23 N° 14 (Novembre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 14 (Novembre 2010) . - pp. 1101–1112 Titre : Coupling oxidation to transient drying during multilayer deposition of thickened gold tailings Type de document : texte imprimé Auteurs : Rachel Bryan, Auteur ; Paul Simms, Auteur ; Rens Verburg, Auteur Année de publication : 2011 Article en page(s) : pp. 1101–1112 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Tailings  disposal  Thickening  Oxidation  Sulfide  ores  Acid  rock  drainage Résumé : Dewatering tailings prior to deposition is an attractive alternative to conventional practice, as it minimizes the use of embankments and therefore reduces the risk of catastrophic failure associated with dammed slurry impoundments. One of the potential detriments is the absence of a water cover and the consequent increase in oxygen ingress and generation of acid drainage. This paper investigates the amount of oxidation that occurs in shallow layers of desiccating gold tailings during deposition. Oxidation is modelled by coupling transient predictions of unsaturated flow to predictions of oxygen diffusive transport and consumption. A first-order rate law is adopted to model oxidation. Coupling is accomplished through the dependency of oxygen diffusivity on degree of saturation. Experiments and numerical predictions agree within the order of the measurement error, despite the relative simplicity of the oxygen consumption model. Though these tailings crack, the cracks do not influence the drying behaviour, nor do they significantly influence the horizontal distribution of oxidation. The modelling method is applied to the case of a fresh layer of tailings deposited over a deep stack. This analysis shows that some oxidation will occur during deposition of a fresh layer of thickened tailings, and the rate of drying and oxidation is strongly influenced by the underlying previously-deposited tailings. It is also illustrated how drying time to achieve a given density, and consequently oxidation, can be limited by hydraulically decoupling a fresh layer from the underlying stack using a capillary break. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268751000172X [article] Coupling oxidation to transient drying during multilayer deposition of thickened gold tailings [texte imprimé] / Rachel Bryan, Auteur ; Paul Simms, Auteur ; Rens Verburg, Auteur . - 2011 . - pp. 1101–1112. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 14 (Novembre 2010) . - pp. 1101–1112 Mots-clés : Tailings  disposal  Thickening  Oxidation  Sulfide  ores  Acid  rock  drainage Résumé : Dewatering tailings prior to deposition is an attractive alternative to conventional practice, as it minimizes the use of embankments and therefore reduces the risk of catastrophic failure associated with dammed slurry impoundments. One of the potential detriments is the absence of a water cover and the consequent increase in oxygen ingress and generation of acid drainage. This paper investigates the amount of oxidation that occurs in shallow layers of desiccating gold tailings during deposition. Oxidation is modelled by coupling transient predictions of unsaturated flow to predictions of oxygen diffusive transport and consumption. A first-order rate law is adopted to model oxidation. Coupling is accomplished through the dependency of oxygen diffusivity on degree of saturation. Experiments and numerical predictions agree within the order of the measurement error, despite the relative simplicity of the oxygen consumption model. Though these tailings crack, the cracks do not influence the drying behaviour, nor do they significantly influence the horizontal distribution of oxidation. The modelling method is applied to the case of a fresh layer of tailings deposited over a deep stack. This analysis shows that some oxidation will occur during deposition of a fresh layer of thickened tailings, and the rate of drying and oxidation is strongly influenced by the underlying previously-deposited tailings. It is also illustrated how drying time to achieve a given density, and consequently oxidation, can be limited by hydraulically decoupling a fresh layer from the underlying stack using a capillary break. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268751000172X

Direct measurement of matric suction in triaxial tests on early-age cemented paste backfill / Paul Simms in Canadian geotechnical journal, Vol. 46 N° 1 (Janvier 2009) 

Public ISBD [article]  in Canadian geotechnical journal > Vol. 46 N° 1 (Janvier 2009) . - pp. 93–101 Titre : Direct measurement of matric suction in triaxial tests on early-age cemented paste backfill Type de document : texte imprimé Auteurs : Paul Simms, Auteur ; Murray Grabinsky, Auteur Article en page(s) : pp. 93–101 Note générale : Sciences de la Terre Langues : Anglais (eng) Mots-clés : Cemented  paste  backfill  Matric  suction  Unsaturated  soil  Cemented  soil  Triaxial  testing  Remblai  de  pâte  cimentée  Matrice  de  succion  Sol  non  saturé  Sol  cimenté  Essais  triaxiaux Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : Hydration occurring in cemented paste backfill (CPB) is shown to generate matric suction through self-desiccation. This complicates determination of the water-retention curve and mechanical properties during curing, which are important in stope design, and renders problematic the use of axis-translation testing procedure to control suctions in strength testing. An alternative is to monitor suction directly during testing. To this end, a miniature tensiometer is inserted into the base of a triaxial cell. A series of unconfined and confined tests are performed on early-age (less than two weeks old) CPB. The observed behaviour is similar to that observed in weakly cemented soils, showing a distinct tendency to dilate during shearing. On a montré que l’hydratation qui se produit dans les remblais de pâte de ciment « CPB » génère une succion matricielle par auto-dessiccation. Ceci complique la détermination de la courbe de rétention d’eau et des propriétés mécaniques durant le mûrissage, qui sont importantes dans la conception de gradins, et rend problématique l’utilisation de la procédure d’essais par translation d’axe pour contrôler les succions dans les essais de résistance. Une alternative consiste à mesurer la succion directement durant l’essai. À cette fin, un tensiomètre miniature est inséré dans la base de la cellule triaxiale. Une série d’essais confinés et non confinés sont réalisés tôt dans l’histoire de la pâte « CPB » (moins de deux semaines). Le comportement observé est similaire à celui observé dans les sols faiblement cimentés, montrant une tendance distincte à se dilater durant le cisaillement. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...] [article] Direct measurement of matric suction in triaxial tests on early-age cemented paste backfill [texte imprimé] / Paul Simms, Auteur ; Murray Grabinsky, Auteur . - pp. 93–101. Sciences de la Terre Langues : Anglais (eng) in Canadian geotechnical journal > Vol. 46 N° 1 (Janvier 2009) . - pp. 93–101 Mots-clés : Cemented  paste  backfill  Matric  suction  Unsaturated  soil  Cemented  soil  Triaxial  testing  Remblai  de  pâte  cimentée  Matrice  de  succion  Sol  non  saturé  Sol  cimenté  Essais  triaxiaux Index. décimale : 550 Sciences auxiliaires de la géologie. Résumé : Hydration occurring in cemented paste backfill (CPB) is shown to generate matric suction through self-desiccation. This complicates determination of the water-retention curve and mechanical properties during curing, which are important in stope design, and renders problematic the use of axis-translation testing procedure to control suctions in strength testing. An alternative is to monitor suction directly during testing. To this end, a miniature tensiometer is inserted into the base of a triaxial cell. A series of unconfined and confined tests are performed on early-age (less than two weeks old) CPB. The observed behaviour is similar to that observed in weakly cemented soils, showing a distinct tendency to dilate during shearing. On a montré que l’hydratation qui se produit dans les remblais de pâte de ciment « CPB » génère une succion matricielle par auto-dessiccation. Ceci complique la détermination de la courbe de rétention d’eau et des propriétés mécaniques durant le mûrissage, qui sont importantes dans la conception de gradins, et rend problématique l’utilisation de la procédure d’essais par translation d’axe pour contrôler les succions dans les essais de résistance. Une alternative consiste à mesurer la succion directement durant l’essai. À cette fin, un tensiomètre miniature est inséré dans la base de la cellule triaxiale. Une série d’essais confinés et non confinés sont réalisés tôt dans l’histoire de la pâte « CPB » (moins de deux semaines). Le comportement observé est similaire à celui observé dans les sols faiblement cimentés, montrant une tendance distincte à se dilater durant le cisaillement. DEWEY : 550 ISSN : 0008-3674 En ligne : http://rparticle.web-p.cisti.nrc.ca/rparticle/AbstractTemplateServlet?calyLang=f [...]

Dynamic imaging and modelling of multilayer deposition of gold paste tailings / Julio Henriquez in Minerals engineering, Vol. 22 N° 2 (Janvier 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 2 (Janvier 2009) . - pp. 128–139 Titre : Dynamic imaging and modelling of multilayer deposition of gold paste tailings Type de document : texte imprimé Auteurs : Julio Henriquez, Auteur ; Paul Simms, Auteur Année de publication : 2009 Article en page(s) : pp. 128–139 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Tailings  disposal  Computational  fluid  dynamics  Environmental  Reclamation Index. décimale : 622 Industrie minière Résumé : Surface deposition of paste or thickened tailings is increasing contemplated as an alternative to conventional slurry deposition. One important challenge in managing paste is to predict the evolving geometry of the tailings stack during deposition. This study dynamically images multilayer deposition of paste in flows in flume and axisymmetric flows. Each layer is left to self-weight consolidate for a day before the next layer is placed. It is found that both the steady-state profiles and the dynamic flows can be modelled as a Bingham fluid using equations developed from lubrication theory. Yield stress and viscosity were determined using rheometry and slump tests. It is shown that the yield stress obtained from the slump test may overestimate the yield stress of significance to flow deposition; namely that yield stress that characterizes when the tailings stop flowing. The lubrication theory equations show that the overall angle of a tailings deposit at steady-state is dependant on the scale of the flow, which may explain the discrepancy between laboratory flume angles and field angles noted in practice. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687508001441 [article] Dynamic imaging and modelling of multilayer deposition of gold paste tailings [texte imprimé] / Julio Henriquez, Auteur ; Paul Simms, Auteur . - 2009 . - pp. 128–139. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 2 (Janvier 2009) . - pp. 128–139 Mots-clés : Tailings  disposal  Computational  fluid  dynamics  Environmental  Reclamation Index. décimale : 622 Industrie minière Résumé : Surface deposition of paste or thickened tailings is increasing contemplated as an alternative to conventional slurry deposition. One important challenge in managing paste is to predict the evolving geometry of the tailings stack during deposition. This study dynamically images multilayer deposition of paste in flows in flume and axisymmetric flows. Each layer is left to self-weight consolidate for a day before the next layer is placed. It is found that both the steady-state profiles and the dynamic flows can be modelled as a Bingham fluid using equations developed from lubrication theory. Yield stress and viscosity were determined using rheometry and slump tests. It is shown that the yield stress obtained from the slump test may overestimate the yield stress of significance to flow deposition; namely that yield stress that characterizes when the tailings stop flowing. The lubrication theory equations show that the overall angle of a tailings deposit at steady-state is dependant on the scale of the flow, which may explain the discrepancy between laboratory flume angles and field angles noted in practice. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687508001441