Documents disponibles écrits par cet auteur

Numerical modelling of non-Newtonian slurry in a mechanical flotation cell / C. W. Bakker in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 944–950 Titre : Numerical modelling of non-Newtonian slurry in a mechanical flotation cell Type de document : texte imprimé Auteurs : C. W. Bakker, Auteur ; C.J. Meyer, Auteur ; D.A. Deglon, Auteur Année de publication : 2009 Article en page(s) : pp. 944–950 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Modelling  Computational  fluid  dynamics  Froth  flotation  Fine  particle  processing  Agitation Résumé : Certain mineral slurries used in the minerals processing industry have been shown to exhibit non-Newtonian rheologies, particularly with finer particle sizes and at higher solid concentrations. Research has also shown that a cavern containing yielded fluid surrounded by stagnant fluid form around the impeller during the agitation of non-Newtonian fluids exhibiting yield stresses, and this is therefore hypothesised to occur inside mechanical flotation cells which may adversely affect fluid hydrodynamics. A single phase non-Newtonian fluids was modelled using CFD, using the Herschel–Bulkley non-Newtonian model with constants derived from experimentally determined Bindura nickel ore slurry, known to be rheologically complex due to the presence of fibrous mineral types, such as serpentine. The modelling methodology was first validated against published experimental results in a stirred tank, and results were experimentally validated using piezoelectric pressure transducers to measure the magnitude of pressure fluctuations due to the fluid velocity in order to define the cavern boundary. Both experimental and numerical findings show that a cavern forms around the stator, with its size depending on slurry yield stress. It was also found that the shear–stress transport (SST) k–ω turbulence model predicted the cavern boundary most accurately. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000958 [article] Numerical modelling of non-Newtonian slurry in a mechanical flotation cell [texte imprimé] / C. W. Bakker, Auteur ; C.J. Meyer, Auteur ; D.A. Deglon, Auteur . - 2009 . - pp. 944–950. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 944–950 Mots-clés : Modelling  Computational  fluid  dynamics  Froth  flotation  Fine  particle  processing  Agitation Résumé : Certain mineral slurries used in the minerals processing industry have been shown to exhibit non-Newtonian rheologies, particularly with finer particle sizes and at higher solid concentrations. Research has also shown that a cavern containing yielded fluid surrounded by stagnant fluid form around the impeller during the agitation of non-Newtonian fluids exhibiting yield stresses, and this is therefore hypothesised to occur inside mechanical flotation cells which may adversely affect fluid hydrodynamics. A single phase non-Newtonian fluids was modelled using CFD, using the Herschel–Bulkley non-Newtonian model with constants derived from experimentally determined Bindura nickel ore slurry, known to be rheologically complex due to the presence of fibrous mineral types, such as serpentine. The modelling methodology was first validated against published experimental results in a stirred tank, and results were experimentally validated using piezoelectric pressure transducers to measure the magnitude of pressure fluctuations due to the fluid velocity in order to define the cavern boundary. Both experimental and numerical findings show that a cavern forms around the stator, with its size depending on slurry yield stress. It was also found that the shear–stress transport (SST) k–ω turbulence model predicted the cavern boundary most accurately. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000958

The development of a cavern model for mechanical flotation cells / C. W. Bakker in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 968–972 Titre : The development of a cavern model for mechanical flotation cells Type de document : texte imprimé Auteurs : C. W. Bakker, Auteur ; C.J. Meyer, Auteur ; D.A. Deglon, Auteur Année de publication : 2011 Article en page(s) : pp. 968–972 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Modelling  Computational  fluid  dynamics  Froth  flotation  Fine  particle  processing  Agitation Résumé : Certain fine particle and high solid concentration mineral slurries used in the froth flotation process have been shown to exhibit non-Newtonian rheologies, including a yield stress. The mixing characteristics of these fluids are often problematic as a cavern of yielded fluid forms around the impeller whilst the rest of the fluid remains stagnant and therefore unmixed. This paper aims to develop a semi-empirical model to calculate the height of caverns forming in non-Newtonian mineral slurries in a mechanical flotation cell. Cavern shapes in a pilot-scale Batequip flotation cell were numerically determined for a range of mineral slurries using an experimentally validated Computational Fluid Dynamics (CFD) model. Development of the cavern height model was based on the assumption that the cavern boundary was formed where the shear stress imposed on the slurry equaled the fluid yield stress and also that the flow along the cell walls could be represented by an annular wall jet. It was found that the cavern height was directly proportional to the product of the slurry density and the square of the impeller tip speed, and inversely proportional to the slurry yield stress. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000725 [article] The development of a cavern model for mechanical flotation cells [texte imprimé] / C. W. Bakker, Auteur ; C.J. Meyer, Auteur ; D.A. Deglon, Auteur . - 2011 . - pp. 968–972. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 968–972 Mots-clés : Modelling  Computational  fluid  dynamics  Froth  flotation  Fine  particle  processing  Agitation Résumé : Certain fine particle and high solid concentration mineral slurries used in the froth flotation process have been shown to exhibit non-Newtonian rheologies, including a yield stress. The mixing characteristics of these fluids are often problematic as a cavern of yielded fluid forms around the impeller whilst the rest of the fluid remains stagnant and therefore unmixed. This paper aims to develop a semi-empirical model to calculate the height of caverns forming in non-Newtonian mineral slurries in a mechanical flotation cell. Cavern shapes in a pilot-scale Batequip flotation cell were numerically determined for a range of mineral slurries using an experimentally validated Computational Fluid Dynamics (CFD) model. Development of the cavern height model was based on the assumption that the cavern boundary was formed where the shear stress imposed on the slurry equaled the fluid yield stress and also that the flow along the cell walls could be represented by an annular wall jet. It was found that the cavern height was directly proportional to the product of the slurry density and the square of the impeller tip speed, and inversely proportional to the slurry yield stress. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000725