Dépouillements

Effect of turbulence models on prediction of fluid flow in an Outotec flotation cell / Jiliang Xia in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 880–885 Titre : Effect of turbulence models on prediction of fluid flow in an Outotec flotation cell Type de document : texte imprimé Auteurs : Jiliang Xia, Auteur ; Antti Rinne, Auteur ; Sami Grönstrand, Auteur Année de publication : 2009 Article en page(s) : pp. 880–885 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  cell  Turbulence  model  Fluid  flow  Power  draw  CFD Résumé : The present paper describes a comparative study of three turbulence models in predicting flows in an Outotec flotation cell. Detailed flow performance and pressure distributions are presented. Results show that two main recirculation zones are formed in the cell. It is revealed that the relatively high pressure coefficient appears on the top zone of stator blades and in the outer rim of rotor blades. A toroidal recirculation zone occurs behind each rotor blade. It is found that the velocity in the toroidal zone is higher than that of the rotor tip speed. These predictions are consistent with experimental observation. It is shown that turbulence model has obvious effect on the prediction of flow. Although similar flow patterns are revealed by different turbulence models, the differences in local variables are observed. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001496 [article] Effect of turbulence models on prediction of fluid flow in an Outotec flotation cell [texte imprimé] / Jiliang Xia, Auteur ; Antti Rinne, Auteur ; Sami Grönstrand, Auteur . - 2009 . - pp. 880–885. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 880–885 Mots-clés : Flotation  cell  Turbulence  model  Fluid  flow  Power  draw  CFD Résumé : The present paper describes a comparative study of three turbulence models in predicting flows in an Outotec flotation cell. Detailed flow performance and pressure distributions are presented. Results show that two main recirculation zones are formed in the cell. It is revealed that the relatively high pressure coefficient appears on the top zone of stator blades and in the outer rim of rotor blades. A toroidal recirculation zone occurs behind each rotor blade. It is found that the velocity in the toroidal zone is higher than that of the rotor tip speed. These predictions are consistent with experimental observation. It is shown that turbulence model has obvious effect on the prediction of flow. Although similar flow patterns are revealed by different turbulence models, the differences in local variables are observed. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001496

Effect of slurry properties on particle motion in IsaMills / C.T. Jayasundara in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 886–892 Titre : Effect of slurry properties on particle motion in IsaMills Type de document : texte imprimé Auteurs : C.T. Jayasundara, Auteur ; R.Y. Yang, Auteur ; B.Y. Guo, Auteur Année de publication : 2009 Article en page(s) : pp. 886–892 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Mineral  processing  Discrete  element  method  Computational  fluid  dynamics  IsaMill™  Stirred  mill Résumé : IsaMill™ is a high-speed stirred mill for a range of milling duties from ultra-fine to relatively coarse grinding in the mineral processing industry. This work investigated particle and slurry flow in a mill using a combined Discrete Element Method and Computational Fluid Dynamics (DEM-CFD) approach. Slurry properties, such as flow density and viscosity, were varied to study their effects on the flow properties in terms of flow velocity, power draw, collision frequency, collision energy and total impact energy. Significant differences were observed when slurry was introduced and other conditions unchanged. With increasing density, fluid and particle flows showed stronger circulation in the axial direction due to the larger drag forces. Increased relative velocity and interaction between particles with disc led to higher collision frequency and collision energy. Increase in flow viscosity limited particles from moving towards the outer wall and the particles were more dispersed due to the larger circulating velocity in the axial direction. The total impact energy of the media and power draw also increase with slurry density and viscosity. The developed model provides a useful framework for further analysis of particle–slurry interactions in IsaMills™. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001162 [article] Effect of slurry properties on particle motion in IsaMills [texte imprimé] / C.T. Jayasundara, Auteur ; R.Y. Yang, Auteur ; B.Y. Guo, Auteur . - 2009 . - pp. 886–892. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 886–892 Mots-clés : Mineral  processing  Discrete  element  method  Computational  fluid  dynamics  IsaMill™  Stirred  mill Résumé : IsaMill™ is a high-speed stirred mill for a range of milling duties from ultra-fine to relatively coarse grinding in the mineral processing industry. This work investigated particle and slurry flow in a mill using a combined Discrete Element Method and Computational Fluid Dynamics (DEM-CFD) approach. Slurry properties, such as flow density and viscosity, were varied to study their effects on the flow properties in terms of flow velocity, power draw, collision frequency, collision energy and total impact energy. Significant differences were observed when slurry was introduced and other conditions unchanged. With increasing density, fluid and particle flows showed stronger circulation in the axial direction due to the larger drag forces. Increased relative velocity and interaction between particles with disc led to higher collision frequency and collision energy. Increase in flow viscosity limited particles from moving towards the outer wall and the particles were more dispersed due to the larger circulating velocity in the axial direction. The total impact energy of the media and power draw also increase with slurry density and viscosity. The developed model provides a useful framework for further analysis of particle–slurry interactions in IsaMills™. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001162

CFD–DEM study of the effect of particle density distribution on the multiphase flow and performance of dense medium cyclone / K. W. Chu in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 893–909 Titre : CFD–DEM study of the effect of particle density distribution on the multiphase flow and performance of dense medium cyclone Type de document : texte imprimé Auteurs : K. W. Chu, Auteur ; B. Wang, Auteur ; A. B. Yu, Auteur Année de publication : 2009 Article en page(s) : pp. 893–909 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Dense  medium  cyclone  Discrete  element  method  Computational  fluid  dynamics  Coal  preparation Résumé : A mathematical model is developed to study the coal-medium flow in a dense medium cyclone (DMC) of 1000 mm body diameter. In the model, the motion of coal particles is obtained using the Discrete Element Method (DEM) facilitated with the concept of “parcel–particle” while the flow of medium as a liquid-magnetite mixture Computational Fluid Dynamics (CFD) based on the local averaged Navier–Stokes equations. In addition the Reynolds Stress Model (RSM) is adopted to describe the anisotropic turbulence, the Volume of Fluid (VOF) model is used to describe the air-core position and multiphase mixture model used to estimate the flow of fine magnetite particles. The simulated medium and coal flows allow estimates to be made of pressure drop, efflux stream medium densities and partition curves for coal particles of different sizes and densities. These estimates are compared favourably with industrial scale measurements of a 1000 mm DMC operating under similar conditions. On this base, the effect of particle density distribution that represents the major difference between two major coal type, i.e., coking coal and thermal coal, is studied. The results are analysed in terms of medium flow pattern, particle flow pattern, partition performance and particle–fluid, particle–wall and particle–particle interaction forces. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001150 [article] CFD–DEM study of the effect of particle density distribution on the multiphase flow and performance of dense medium cyclone [texte imprimé] / K. W. Chu, Auteur ; B. Wang, Auteur ; A. B. Yu, Auteur . - 2009 . - pp. 893–909. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 893–909 Mots-clés : Dense  medium  cyclone  Discrete  element  method  Computational  fluid  dynamics  Coal  preparation Résumé : A mathematical model is developed to study the coal-medium flow in a dense medium cyclone (DMC) of 1000 mm body diameter. In the model, the motion of coal particles is obtained using the Discrete Element Method (DEM) facilitated with the concept of “parcel–particle” while the flow of medium as a liquid-magnetite mixture Computational Fluid Dynamics (CFD) based on the local averaged Navier–Stokes equations. In addition the Reynolds Stress Model (RSM) is adopted to describe the anisotropic turbulence, the Volume of Fluid (VOF) model is used to describe the air-core position and multiphase mixture model used to estimate the flow of fine magnetite particles. The simulated medium and coal flows allow estimates to be made of pressure drop, efflux stream medium densities and partition curves for coal particles of different sizes and densities. These estimates are compared favourably with industrial scale measurements of a 1000 mm DMC operating under similar conditions. On this base, the effect of particle density distribution that represents the major difference between two major coal type, i.e., coking coal and thermal coal, is studied. The results are analysed in terms of medium flow pattern, particle flow pattern, partition performance and particle–fluid, particle–wall and particle–particle interaction forces. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001150

DEM simulation of particle flow on a multi-deck banana screen / K. J. Dong in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 910–920 Titre : DEM simulation of particle flow on a multi-deck banana screen Type de document : texte imprimé Auteurs : K. J. Dong, Auteur ; A. B. Yu, Auteur ; I. Brake, Auteur Année de publication : 2009 Article en page(s) : pp. 910–920 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Screening  Coal  preparation  Discrete  Element  Method  Process  simulation Résumé : Banana screen is an important innovation in screening process in the past decades to improve screen capacity. Although, it is increasingly employed in the mineral industry, the control and optimisation are still limited due to the lack of fundamental understandings of the process. This paper presents a numerical study of the particle flow on a banana screen at a particle scale by means of Discrete Element Method (DEM). Typical 3-deck and 5-deck banana screens are simulated. The effects of operational conditions and geometry on the screen performance are studied by a series of controlled numerical experiments. The results are analysed in terms of partition curves, distributions of percentage passing and other flow information, such as particle volume and velocities along the screen deck. They are useful to the development of a better understanding and the control of banana screening processes. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001046 [article] DEM simulation of particle flow on a multi-deck banana screen [texte imprimé] / K. J. Dong, Auteur ; A. B. Yu, Auteur ; I. Brake, Auteur . - 2009 . - pp. 910–920. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 910–920 Mots-clés : Screening  Coal  preparation  Discrete  Element  Method  Process  simulation Résumé : Banana screen is an important innovation in screening process in the past decades to improve screen capacity. Although, it is increasingly employed in the mineral industry, the control and optimisation are still limited due to the lack of fundamental understandings of the process. This paper presents a numerical study of the particle flow on a banana screen at a particle scale by means of Discrete Element Method (DEM). Typical 3-deck and 5-deck banana screens are simulated. The effects of operational conditions and geometry on the screen performance are studied by a series of controlled numerical experiments. The results are analysed in terms of partition curves, distributions of percentage passing and other flow information, such as particle volume and velocities along the screen deck. They are useful to the development of a better understanding and the control of banana screening processes. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001046

DEM simulation of cake formation in sedimentation and filtration / K. J. Dong in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 921–930 Titre : DEM simulation of cake formation in sedimentation and filtration Type de document : texte imprimé Auteurs : K. J. Dong, Auteur ; R. P. Zou, Auteur ; R.Y. Yang, Auteur Année de publication : 2009 Article en page(s) : pp. 921–930 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Liquid–solid  separation  Sedimentation  Filtration  Particle  packing  Discrete  element  method Résumé : This paper presents a DEM study of cake formation and growth in sedimentation and filtration processes with constant flow rate or pressure. The liquid flow is assumed to be one-dimensional and the motion of particles is three-dimensional. Various forces are included to determine the motion of particles, including the particle–particle contact forces, the van der Waals force and the particle–fluid interactions such as buoyancy, drag and lift forces. The effects of the material properties of particles and liquid and the operational conditions are examined. The structures of cakes are also analysed and the relationship between cake porosity and interparticle force is quantified. The microscopic analysis demonstrates that these variables affect the process and the cake structures through their effects on the gravity or cohesive force, which competes in controlling the formation of a cake. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001010 [article] DEM simulation of cake formation in sedimentation and filtration [texte imprimé] / K. J. Dong, Auteur ; R. P. Zou, Auteur ; R.Y. Yang, Auteur . - 2009 . - pp. 921–930. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 921–930 Mots-clés : Liquid–solid  separation  Sedimentation  Filtration  Particle  packing  Discrete  element  method Résumé : This paper presents a DEM study of cake formation and growth in sedimentation and filtration processes with constant flow rate or pressure. The liquid flow is assumed to be one-dimensional and the motion of particles is three-dimensional. Various forces are included to determine the motion of particles, including the particle–particle contact forces, the van der Waals force and the particle–fluid interactions such as buoyancy, drag and lift forces. The effects of the material properties of particles and liquid and the operational conditions are examined. The structures of cakes are also analysed and the relationship between cake porosity and interparticle force is quantified. The microscopic analysis demonstrates that these variables affect the process and the cake structures through their effects on the gravity or cohesive force, which competes in controlling the formation of a cake. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001010

Numerical studies of the effects of medium properties in dense medium cyclone operations / B. Wang in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 931–943 Titre : Numerical studies of the effects of medium properties in dense medium cyclone operations Type de document : texte imprimé Auteurs : B. Wang, Auteur ; K. W. Chu, Auteur ; A. B. Yu, Auteur Année de publication : 2009 Article en page(s) : pp. 931–943 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Dense  medium  cyclone  Multiphase  flow  Computational  fluid  dynamics  Separations Résumé : A mathematical approach is proposed to describe the multiphase flow in a 1000 mm industrial dense medium cyclone. A mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite contaminated with non-magnetic material in water) and the air core, where the turbulence is described by the well established Reynolds stress model. The stochastic Lagrangian particle tracking method is used to simulate the flow of coal particles. The proposed approach was qualitatively validated using literature and industrial data and then used to study the effects of medium properties including medium density, magnetite type and non-magnetic content. It is found that as the medium density increases, the pressure drop increases, resulting in a high pressure gradient force on coal particles and reduced separating efficiencies. The segregation of magnetite particles becomes serious as magnetite particle size increases, which leads to a high density differential and a high off-set. The viscosity of medium decreases and the segregation of magnetite particles become significant with the decrease of non-magnetic content, resulting in a high density differential and off-set. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001009 [article] Numerical studies of the effects of medium properties in dense medium cyclone operations [texte imprimé] / B. Wang, Auteur ; K. W. Chu, Auteur ; A. B. Yu, Auteur . - 2009 . - pp. 931–943. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 931–943 Mots-clés : Dense  medium  cyclone  Multiphase  flow  Computational  fluid  dynamics  Separations Résumé : A mathematical approach is proposed to describe the multiphase flow in a 1000 mm industrial dense medium cyclone. A mixture multiphase model is employed to describe the flow of the dense medium (comprising finely ground magnetite contaminated with non-magnetic material in water) and the air core, where the turbulence is described by the well established Reynolds stress model. The stochastic Lagrangian particle tracking method is used to simulate the flow of coal particles. The proposed approach was qualitatively validated using literature and industrial data and then used to study the effects of medium properties including medium density, magnetite type and non-magnetic content. It is found that as the medium density increases, the pressure drop increases, resulting in a high pressure gradient force on coal particles and reduced separating efficiencies. The segregation of magnetite particles becomes serious as magnetite particle size increases, which leads to a high density differential and a high off-set. The viscosity of medium decreases and the segregation of magnetite particles become significant with the decrease of non-magnetic content, resulting in a high density differential and off-set. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001009

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

Mathematical modeling of thermophilic bioleaching of chalcopyrite / Javier Vilcáez in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 951–960 Titre : Mathematical modeling of thermophilic bioleaching of chalcopyrite Type de document : texte imprimé Auteurs : Javier Vilcáez, Auteur ; Chihiro Inoue, Auteur Année de publication : 2009 Article en page(s) : pp. 951–960 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Sulphide  ores  Bioleaching  Reaction  kinetics  Modelling Résumé : Previous studies have shown that the different preferences of thermophiles to oxidize S0 or Fe2+ is reflected by different [Fe3+]/[Fe2+] levels in solution. In those studies it was concluded that [Fe3+]/[Fe2+] governs the thermophilic bioleaching of chalcopyrite rather than temperature or pH. Therefore, the proposed model is mainly based on the finding that thermophilic bioleaching of chalcopyrite is governed by [Fe3+]/[Fe2+] that result from the activity of thermophiles. A direct interaction between chalcopyrite and thermophiles is neglected because it has been reported that this is not a general behavior for all thermophiles. The case of constant temperature, initial pH 1.5–2.5, and chalcopyrite concentrates is considered. The main assumption is that chalcopyrite can be anodically oxidized or cathodically reduced depending on [Fe3+]/[Fe2+] in solution. When chalcopyrite is oxidized at high [Fe3+]/[Fe2+] levels, Cu2+ is formed directly at low rates: CuFeS2 + 4Fe3+ → Cu2+ + 5Fe2+ + S0. Whereas, when chalcopyrite is reduced at low [Fe3+]/[Fe2+] levels, an intermediate (Cu2S) is formed at higher rates: CuFeS2 + Fe2+ + Cu2+ + 2H+ → Cu2S + 2Fe3+ + H2S. Because the oxidation of Cu2S is relatively fast: Cu2S + 4Fe3+ → 2Cu2+ + S0 + 4Fe2+, its accumulation is assumed to be negligible. To take into account the possibility of chalcopyrite being oxidized or reduced depending on [Fe3+]/[Fe2+] in solution, the principle of mixed potentials is used. The model is validated by comparing the calculated and measured values of copper extraction, total iron in solution, and pH. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268750900079X [article] Mathematical modeling of thermophilic bioleaching of chalcopyrite [texte imprimé] / Javier Vilcáez, Auteur ; Chihiro Inoue, Auteur . - 2009 . - pp. 951–960. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 951–960 Mots-clés : Sulphide  ores  Bioleaching  Reaction  kinetics  Modelling Résumé : Previous studies have shown that the different preferences of thermophiles to oxidize S0 or Fe2+ is reflected by different [Fe3+]/[Fe2+] levels in solution. In those studies it was concluded that [Fe3+]/[Fe2+] governs the thermophilic bioleaching of chalcopyrite rather than temperature or pH. Therefore, the proposed model is mainly based on the finding that thermophilic bioleaching of chalcopyrite is governed by [Fe3+]/[Fe2+] that result from the activity of thermophiles. A direct interaction between chalcopyrite and thermophiles is neglected because it has been reported that this is not a general behavior for all thermophiles. The case of constant temperature, initial pH 1.5–2.5, and chalcopyrite concentrates is considered. The main assumption is that chalcopyrite can be anodically oxidized or cathodically reduced depending on [Fe3+]/[Fe2+] in solution. When chalcopyrite is oxidized at high [Fe3+]/[Fe2+] levels, Cu2+ is formed directly at low rates: CuFeS2 + 4Fe3+ → Cu2+ + 5Fe2+ + S0. Whereas, when chalcopyrite is reduced at low [Fe3+]/[Fe2+] levels, an intermediate (Cu2S) is formed at higher rates: CuFeS2 + Fe2+ + Cu2+ + 2H+ → Cu2S + 2Fe3+ + H2S. Because the oxidation of Cu2S is relatively fast: Cu2S + 4Fe3+ → 2Cu2+ + S0 + 4Fe2+, its accumulation is assumed to be negligible. To take into account the possibility of chalcopyrite being oxidized or reduced depending on [Fe3+]/[Fe2+] in solution, the principle of mixed potentials is used. The model is validated by comparing the calculated and measured values of copper extraction, total iron in solution, and pH. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268750900079X

Effect of particle properties on particle percolation behaviour in a packed bed / H.P. Zhu in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 961–969 Titre : Effect of particle properties on particle percolation behaviour in a packed bed Type de document : texte imprimé Auteurs : H.P. Zhu, Auteur ; M. Rahman, Auteur ; A. B. Yu, Auteur Année de publication : 2009 Article en page(s) : pp. 961–969 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Discrete  element  modelling  Particle  size  Mineral  processing  Process  control Résumé : Spontaneous inter-particle percolation is a very important phenomenon related to the mixing/segregation of particulate materials. Many studies have been conducted to understand the mechanisms governing the percolation behaviours in the past. However, previous work has a lack of systematic investigation on the effect of particle properties. In this work, a layer of small particles passing through a packed bed under gravity is analysed by means of the discrete element method. Percolation behaviour in terms of percolation velocity and radial dispersion is studied. The effect of percolating particle properties, including sliding friction and damping coefficients between percolating and packing particles, density and diameter ratios of percolating to packing particles and Young’s modulus of percolating particles, on the percolation behaviour is considered. It is observed that the damping coefficient and diameter ratio are the two dominant parameters that significantly affect the percolation behaviour. In particular, increasing the damping coefficient or decreasing the diameter ratio would increase the percolation velocity and decrease the radial dispersion. The sliding friction coefficient, Young’s modulus and density ratio have limited effects on the percolation behaviour. Two formulas have been, respectively, proposed to describe the dependences of percolation velocity and interaction force between percolating and packing particles on damping coefficient and diameter ratio. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000788 [article] Effect of particle properties on particle percolation behaviour in a packed bed [texte imprimé] / H.P. Zhu, Auteur ; M. Rahman, Auteur ; A. B. Yu, Auteur . - 2009 . - pp. 961–969. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 961–969 Mots-clés : Discrete  element  modelling  Particle  size  Mineral  processing  Process  control Résumé : Spontaneous inter-particle percolation is a very important phenomenon related to the mixing/segregation of particulate materials. Many studies have been conducted to understand the mechanisms governing the percolation behaviours in the past. However, previous work has a lack of systematic investigation on the effect of particle properties. In this work, a layer of small particles passing through a packed bed under gravity is analysed by means of the discrete element method. Percolation behaviour in terms of percolation velocity and radial dispersion is studied. The effect of percolating particle properties, including sliding friction and damping coefficients between percolating and packing particles, density and diameter ratios of percolating to packing particles and Young’s modulus of percolating particles, on the percolation behaviour is considered. It is observed that the damping coefficient and diameter ratio are the two dominant parameters that significantly affect the percolation behaviour. In particular, increasing the damping coefficient or decreasing the diameter ratio would increase the percolation velocity and decrease the radial dispersion. The sliding friction coefficient, Young’s modulus and density ratio have limited effects on the percolation behaviour. Two formulas have been, respectively, proposed to describe the dependences of percolation velocity and interaction force between percolating and packing particles on damping coefficient and diameter ratio. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000788

Prediction of coal response to froth flotation based on coal analysis using regression and artificial neural network / E. Jorjani in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 970–976 Titre : Prediction of coal response to froth flotation based on coal analysis using regression and artificial neural network Type de document : texte imprimé Auteurs : E. Jorjani, Auteur ; H. Asadollahi Poorali, Auteur ; A. Sam, Auteur Année de publication : 2009 Article en page(s) : pp. 970–976 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Coal  Neural  networks  Froth  flotation  Modeling Résumé : In this paper, the combustible value (i.e. 100-Ash) and combustible recovery of coal flotation concentrate were predicted by regression and artificial neural network based on proximate and group macerals analysis. The regression method shows that the relationships between (a) ln (ash), volatile matter and moisture (b) ln (ash), ln (liptinite), fusinite and vitrinite with combustible value can achieve the correlation coefficients (R2) of 0.8 and 0.79, respectively. In addition, the input sets of (c) ash, volatile matter and moisture (d) ash, liptinite and fusinite can predict the combustible recovery with the correlation coefficients of 0.84 and 0.63, respectively. Feed-forward artificial neural network with 6-8-12-11-2-1 arrangement for moisture, ash and volatile matter input set was capable to estimate both combustible value and combustible recovery with correlation of 0.95. It was shown that the proposed neural network model could accurately reproduce all the effects of proximate and group macerals analysis on coal flotation system. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000776 [article] Prediction of coal response to froth flotation based on coal analysis using regression and artificial neural network [texte imprimé] / E. Jorjani, Auteur ; H. Asadollahi Poorali, Auteur ; A. Sam, Auteur . - 2009 . - pp. 970–976. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 970–976 Mots-clés : Coal  Neural  networks  Froth  flotation  Modeling Résumé : In this paper, the combustible value (i.e. 100-Ash) and combustible recovery of coal flotation concentrate were predicted by regression and artificial neural network based on proximate and group macerals analysis. The regression method shows that the relationships between (a) ln (ash), volatile matter and moisture (b) ln (ash), ln (liptinite), fusinite and vitrinite with combustible value can achieve the correlation coefficients (R2) of 0.8 and 0.79, respectively. In addition, the input sets of (c) ash, volatile matter and moisture (d) ash, liptinite and fusinite can predict the combustible recovery with the correlation coefficients of 0.84 and 0.63, respectively. Feed-forward artificial neural network with 6-8-12-11-2-1 arrangement for moisture, ash and volatile matter input set was capable to estimate both combustible value and combustible recovery with correlation of 0.95. It was shown that the proposed neural network model could accurately reproduce all the effects of proximate and group macerals analysis on coal flotation system. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000776

Thermodynamic modelling of the multiphase pyrometallurgical processing of electric arc furnace dust / C.A. Pickles in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 977–985 Titre : Thermodynamic modelling of the multiphase pyrometallurgical processing of electric arc furnace dust Type de document : texte imprimé Auteurs : C.A. Pickles, Auteur Année de publication : 2009 Article en page(s) : pp. 977–985 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flue  dusts  Pyrometallurgy  Reduction  Recycling  Waste  processing Résumé : Electric arc furnace (EAF) dust is produced when automobile scrap is remelted in an electric arc furnace and about 10–20 kilograms are generated per ton of steel. The major elements present in the dust are usually zinc, iron and calcium with smaller amounts of numerous other elements such as lead, copper and nickel. Typically, in the pyrometallurgical EAF dust treatment processes, the lead and zinc are separated as a crude zinc oxide while the iron is generally not worth recovering. Copper and nickel are usually not recovered as they report either to the oxide residue or to any metallic iron that is produced. In the present research, the recovery of the non-ferrous metals in a multiphase system consisting of gas, slag, matte, metal and solid carbon phases was investigated. The equilibrium compositions of the various phases, resulting from the smelting of the dust, were calculated using the SOLGASMIX module of Outokumpu HSC Chemistry. The effects of the following operating variables were investigated; carbon additions, sulphur additions, nitrogen and oxygen additions, temperature and dust composition. The thermodynamic modelling results show that the majority of the non-ferrous metals can be recovered, with the zinc and lead concentrating in the gas phase and the nickel and copper concentrating in the matte phase. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000764 [article] Thermodynamic modelling of the multiphase pyrometallurgical processing of electric arc furnace dust [texte imprimé] / C.A. Pickles, Auteur . - 2009 . - pp. 977–985. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 977–985 Mots-clés : Flue  dusts  Pyrometallurgy  Reduction  Recycling  Waste  processing Résumé : Electric arc furnace (EAF) dust is produced when automobile scrap is remelted in an electric arc furnace and about 10–20 kilograms are generated per ton of steel. The major elements present in the dust are usually zinc, iron and calcium with smaller amounts of numerous other elements such as lead, copper and nickel. Typically, in the pyrometallurgical EAF dust treatment processes, the lead and zinc are separated as a crude zinc oxide while the iron is generally not worth recovering. Copper and nickel are usually not recovered as they report either to the oxide residue or to any metallic iron that is produced. In the present research, the recovery of the non-ferrous metals in a multiphase system consisting of gas, slag, matte, metal and solid carbon phases was investigated. The equilibrium compositions of the various phases, resulting from the smelting of the dust, were calculated using the SOLGASMIX module of Outokumpu HSC Chemistry. The effects of the following operating variables were investigated; carbon additions, sulphur additions, nitrogen and oxygen additions, temperature and dust composition. The thermodynamic modelling results show that the majority of the non-ferrous metals can be recovered, with the zinc and lead concentrating in the gas phase and the nickel and copper concentrating in the matte phase. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000764

Experimental and numerical investigations of gouge formation related to blast furnace burden distribution / C.K. Ho in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 986–994 Titre : Experimental and numerical investigations of gouge formation related to blast furnace burden distribution Type de document : texte imprimé Auteurs : C.K. Ho, Auteur ; S.M. Wu, Auteur ; H.P. Zhu, Auteur Année de publication : 2009 Article en page(s) : pp. 986–994 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Discreet  element  modeling  Mineral  processing  Extractive  metallurgy  Process  control Résumé : This paper presents an experimental and numerical study of the gouge formation related to burden distribution in a BF. Physical experiments are conducted using a simplified bell-less charging model. The results indicate that the burden distribution is affected by particle properties such as density and size, and geometry of experimental set-up such as chute angle and distance between bin and chute. The gouge area generated is related to the ratio of the input energy from the top layer to the inertial energy from the base layer for the cases with red wooden balls, large glass beads and large steel balls. Numerical experiments are performed by means of the discrete element method. It is shown that the simulation model can reproduce the experimental results well. The weight ratio distribution is found to be largely affected by the densities of materials. The force structures are also analyzed to understand the fundamentals of the formation of the burden profiles. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000752 [article] Experimental and numerical investigations of gouge formation related to blast furnace burden distribution [texte imprimé] / C.K. Ho, Auteur ; S.M. Wu, Auteur ; H.P. Zhu, Auteur . - 2009 . - pp. 986–994. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 986–994 Mots-clés : Discreet  element  modeling  Mineral  processing  Extractive  metallurgy  Process  control Résumé : This paper presents an experimental and numerical study of the gouge formation related to burden distribution in a BF. Physical experiments are conducted using a simplified bell-less charging model. The results indicate that the burden distribution is affected by particle properties such as density and size, and geometry of experimental set-up such as chute angle and distance between bin and chute. The gouge area generated is related to the ratio of the input energy from the top layer to the inertial energy from the base layer for the cases with red wooden balls, large glass beads and large steel balls. Numerical experiments are performed by means of the discrete element method. It is shown that the simulation model can reproduce the experimental results well. The weight ratio distribution is found to be largely affected by the densities of materials. The force structures are also analyzed to understand the fundamentals of the formation of the burden profiles. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000752

Computational fluid dynamic modelling of an electric furnace used in the smelting of PGM containing concentrates / J. J. Bezuidenhout in Minerals engineering, Vol. 22 N° 11 (Octobre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 995–1006 Titre : Computational fluid dynamic modelling of an electric furnace used in the smelting of PGM containing concentrates Type de document : texte imprimé Auteurs : J. J. Bezuidenhout, Auteur ; J.J. Eksteen, Auteur ; S. M. Bradshaw, Auteur Année de publication : 2009 Article en page(s) : pp. 995–1006 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Modelling  Electric  refining  Pyrometallurgy Résumé : A complete three-dimensional computational fluid dynamic model has been developed to investigate the internal dynamics of a circular, three-phase electrical furnace as used for the smelting of Platinum Group Metal (PGM) concentrates. The model included multi-phase interactions between multiple fluid layers and CO-gas bubble release from the immersed electrode surface while three-phase AC electrical current was simulated at the electrodes. The model further accounts for the heat associated with the melting of concentrate which was thermodynamically calculated and incorporated by assuming zones of varying smelting intensity within the concentrate layer. The relationship between electrode immersion depths, at 15%, 35% and 55% in the slag, and the current distribution and slag electrical resistivity has been quantified while the temperature and velocity fields were obtained for 35% electrode immersion model, a typical operation case. The slag was identified as being at a fairly uniform temperature due to the mixing induced by natural buoyancy and the CO-bubble-momentum with the highest flow noted between and directly around the electrodes. The matte showed a stratified temperature distribution with little flow activity. The model results were found to correlate well with previously published studies and actual operating parameters. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000740 [article] Computational fluid dynamic modelling of an electric furnace used in the smelting of PGM containing concentrates [texte imprimé] / J. J. Bezuidenhout, Auteur ; J.J. Eksteen, Auteur ; S. M. Bradshaw, Auteur . - 2009 . - pp. 995–1006. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 11 (Octobre 2009) . - pp. 995–1006 Mots-clés : Computational  fluid  dynamics  Modelling  Electric  refining  Pyrometallurgy Résumé : A complete three-dimensional computational fluid dynamic model has been developed to investigate the internal dynamics of a circular, three-phase electrical furnace as used for the smelting of Platinum Group Metal (PGM) concentrates. The model included multi-phase interactions between multiple fluid layers and CO-gas bubble release from the immersed electrode surface while three-phase AC electrical current was simulated at the electrodes. The model further accounts for the heat associated with the melting of concentrate which was thermodynamically calculated and incorporated by assuming zones of varying smelting intensity within the concentrate layer. The relationship between electrode immersion depths, at 15%, 35% and 55% in the slag, and the current distribution and slag electrical resistivity has been quantified while the temperature and velocity fields were obtained for 35% electrode immersion model, a typical operation case. The slag was identified as being at a fairly uniform temperature due to the mixing induced by natural buoyancy and the CO-bubble-momentum with the highest flow noted between and directly around the electrodes. The matte showed a stratified temperature distribution with little flow activity. The model results were found to correlate well with previously published studies and actual operating parameters. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509000740

Exemplaires

Bibliothèque Ecole Nationale Polytechnique d'Alger

Accueil

Se connecter

Météo

Adresse