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Combining Positron Emission Particle Tracking and image analysis to interpret particle motion in froths / K.E. Cole in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1036–1044 Titre : Combining Positron Emission Particle Tracking and image analysis to interpret particle motion in froths Type de document : texte imprimé Auteurs : K.E. Cole, Auteur ; K.E. Waters, Auteur ; X. Fan, Auteur Année de publication : 2011 Article en page(s) : pp. 1036–1044 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  froths  Flotation  bubbles  Froth  flotation Résumé : Previous research into particle motion in the froth zone has focussed on constructing detailed CFD models that describe the behaviour of particle classes with different properties; density, size and hydrophobicity. These models have been reasonably successful in predicting trends in the separation behaviour and how it can be manipulated. Models of separation sub-processes cannot readily be verified experimentally due to the opacity and fragility of froth systems. Positron Emission Particle Tracking (PEPT) can be applied to particles in froth flotation systems to observe the behaviour of individual particles in a mixed particle–liquid–gas system. However, measuring the particle position alone is not adequate as its behaviour is also affected by instantaneous froth events such as bubble coalescence. To link the observed particle behaviour to the froth behaviour requires multi-modal measurements. Video footage of a rising foam column was recorded simultaneously with PEPT data, so that the PEPT tracer trajectory could be explained in terms of foam structure and events. A time weighting function of cubic splines with kernel width 200 ms was used to remove the effects of signal noise. An ascending 70 μm hydrophilic tracer accelerated within vertical Plateau borders and decelerated in Plateau borders angled away from vertical. The tracer trajectory showed velocity peaks and troughs when it was contained in nodes in a rising foam. When the tracer descended within a foam showing convective roll, coalescence events and subsequent foam deformation directly influenced the tracer trajectory. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001457 [article] Combining Positron Emission Particle Tracking and image analysis to interpret particle motion in froths [texte imprimé] / K.E. Cole, Auteur ; K.E. Waters, Auteur ; X. Fan, Auteur . - 2011 . - pp. 1036–1044. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1036–1044 Mots-clés : Flotation  froths  Flotation  bubbles  Froth  flotation Résumé : Previous research into particle motion in the froth zone has focussed on constructing detailed CFD models that describe the behaviour of particle classes with different properties; density, size and hydrophobicity. These models have been reasonably successful in predicting trends in the separation behaviour and how it can be manipulated. Models of separation sub-processes cannot readily be verified experimentally due to the opacity and fragility of froth systems. Positron Emission Particle Tracking (PEPT) can be applied to particles in froth flotation systems to observe the behaviour of individual particles in a mixed particle–liquid–gas system. However, measuring the particle position alone is not adequate as its behaviour is also affected by instantaneous froth events such as bubble coalescence. To link the observed particle behaviour to the froth behaviour requires multi-modal measurements. Video footage of a rising foam column was recorded simultaneously with PEPT data, so that the PEPT tracer trajectory could be explained in terms of foam structure and events. A time weighting function of cubic splines with kernel width 200 ms was used to remove the effects of signal noise. An ascending 70 μm hydrophilic tracer accelerated within vertical Plateau borders and decelerated in Plateau borders angled away from vertical. The tracer trajectory showed velocity peaks and troughs when it was contained in nodes in a rising foam. When the tracer descended within a foam showing convective roll, coalescence events and subsequent foam deformation directly influenced the tracer trajectory. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001457

Froth touch samples viewed with scanning electron microscopy / K.E. Cole in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1018–1022 Titre : Froth touch samples viewed with scanning electron microscopy Type de document : texte imprimé Auteurs : K.E. Cole, Auteur ; G.D.M. Morris, Auteur ; J. J. Cilliers, Auteur Année de publication : 2011 Article en page(s) : pp. 1018–1022 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  froths  Modelling  Particle  size  Sampling Résumé : The stability of the thin films found in the froth phase of flotation plays an important role in the overall efficiency of the separation process. In turn, the physical behaviour of the particles attached to the films has a direct impact on the lamella stability. This effect is not fully understood. The film solids loading, or attached mass to area ratio, is an indicator of froth stability and has been measured by touch sampling of surface bubbles. Multiple samples can also be assayed as an indicator of maximum possible grade. Here the touch sample technique is used to show the particle packing arrangement on the film. This work presents images of touch samples from the top of the froth viewed under a Scanning Electron Microscope (SEM). Froth samples were obtained during batch flotation of glass beads with a size fraction of 90–150 μm. The packing arrangement of the particles attached to the surface lamellae were clearly resolved, making it possible to obtain a measure of film packing density using image analysis. These results can be used to validate and expand physical models that predict film stability. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001238 [article] Froth touch samples viewed with scanning electron microscopy [texte imprimé] / K.E. Cole, Auteur ; G.D.M. Morris, Auteur ; J. J. Cilliers, Auteur . - 2011 . - pp. 1018–1022. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1018–1022 Mots-clés : Flotation  froths  Modelling  Particle  size  Sampling Résumé : The stability of the thin films found in the froth phase of flotation plays an important role in the overall efficiency of the separation process. In turn, the physical behaviour of the particles attached to the films has a direct impact on the lamella stability. This effect is not fully understood. The film solids loading, or attached mass to area ratio, is an indicator of froth stability and has been measured by touch sampling of surface bubbles. Multiple samples can also be assayed as an indicator of maximum possible grade. Here the touch sample technique is used to show the particle packing arrangement on the film. This work presents images of touch samples from the top of the froth viewed under a Scanning Electron Microscope (SEM). Froth samples were obtained during batch flotation of glass beads with a size fraction of 90–150 μm. The packing arrangement of the particles attached to the surface lamellae were clearly resolved, making it possible to obtain a measure of film packing density using image analysis. These results can be used to validate and expand physical models that predict film stability. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001238