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Application of closely spaced inclined channels in gravity separation of fine particles / K. P. Galvin in Minerals engineering, Vol. 23 N° 4 (Mars 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 4 (Mars 2010) . - pp. 326–338 Titre : Application of closely spaced inclined channels in gravity separation of fine particles Type de document : texte imprimé Auteurs : K. P. Galvin, Auteur ; J. Zhou, Auteur ; K. Walton, Auteur Année de publication : 2011 Article en page(s) : pp. 326–338 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Coal  Gravity  concentration  Elutriation  Oxide  ores  Gold  ores Résumé : This paper is concerned with the gravity separation of fine particles in a Reflux Classifier, a fluidized bed device with a system of parallel inclined channels located above. A significant advance is reported here over what was previously possible, through the application of a recent discovery described by Galvin et al. (2009). By using closely spaced inclined channels it is possible to achieve significant suppression of the effects of particle size, and hence produce a powerful separation on the basis of density. Experimental work was undertaken on the continuous steady state separation of coal and mineral matter, with a very narrow channel spacing of 1.77 mm used to process a feed finer than 0.5 mm in diameter, and a channel spacing of 4.2 mm used to process coarser feeds finer than 2.0 mm. These results are compared with previous findings reported in the literature for wider channels. The gravity separation performance is shown to be remarkably high, with a significant reduction in the variation of the separation density with particle size, and a significant reduction in the Ecart probable error, Ep. For example, over the particle size range 0.25–2.0 mm the composite Ep for the size range decreased from 0.14 for the wide channels used in previous studies to a typical level of 0.06 for the closely spaced inclined channels used in the present study. The separation performance was also shown to be insensitive to feed pulp density and feed solids throughput over a very broad range. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509002404 [article] Application of closely spaced inclined channels in gravity separation of fine particles [texte imprimé] / K. P. Galvin, Auteur ; J. Zhou, Auteur ; K. Walton, Auteur . - 2011 . - pp. 326–338. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 4 (Mars 2010) . - pp. 326–338 Mots-clés : Coal  Gravity  concentration  Elutriation  Oxide  ores  Gold  ores Résumé : This paper is concerned with the gravity separation of fine particles in a Reflux Classifier, a fluidized bed device with a system of parallel inclined channels located above. A significant advance is reported here over what was previously possible, through the application of a recent discovery described by Galvin et al. (2009). By using closely spaced inclined channels it is possible to achieve significant suppression of the effects of particle size, and hence produce a powerful separation on the basis of density. Experimental work was undertaken on the continuous steady state separation of coal and mineral matter, with a very narrow channel spacing of 1.77 mm used to process a feed finer than 0.5 mm in diameter, and a channel spacing of 4.2 mm used to process coarser feeds finer than 2.0 mm. These results are compared with previous findings reported in the literature for wider channels. The gravity separation performance is shown to be remarkably high, with a significant reduction in the variation of the separation density with particle size, and a significant reduction in the Ecart probable error, Ep. For example, over the particle size range 0.25–2.0 mm the composite Ep for the size range decreased from 0.14 for the wide channels used in previous studies to a typical level of 0.06 for the closely spaced inclined channels used in the present study. The separation performance was also shown to be insensitive to feed pulp density and feed solids throughput over a very broad range. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509002404

Density based separations in the Reflux Classifier with an air–sand dense–medium and vibration / S. A. Macpherson in Minerals engineering, Vol. 23 N° 2 (Janvier 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 2 (Janvier 2010) . - pp. 74-82 Titre : Density based separations in the Reflux Classifier with an air–sand dense–medium and vibration Type de document : texte imprimé Auteurs : S. A. Macpherson, Auteur ; S. M. Iveson, Auteur ; K. P. Galvin, Auteur Article en page(s) : pp. 74-82 Note générale : Génie Minier Métallurgie Langues : Anglais (eng) Mots-clés : Dense  medium  separation  Gravity  concentration  Coal Index. décimale : 622 Industrie minière Résumé : The Reflux Classifier is a device consisting of parallel inclined channels above a fluidized bed. Water-based versions of the system have been successfully employed in industry for gravity separation of −2 + 0.25 mm coal and mineral matter. In this study an air-fluidized system was investigated using a single 2 m long inclined channel with 100 mm wide channels and 20 mm perpendicular spacing. Sand (−355 + 125 micron) was used as a dense–medium and vibration at two distinct levels was used to improve fluidization stability. Tracer particles of −6.35 + 1.00 mm nominal diameter and 1300 to 2400 kg/m3 density were used to study the effects of the vibration energy and vibration direction on the separation efficiency. The device was able to separate coal particles from a maximum of 8 mm down to 1 mm on the basis of density; hence this method has potential for industrial application. Results were analysed using a simple 2-parameter dispersion–convection model. Dense particles had negative slip velocities, low-density particles had positive slip velocities and the slip velocities were proportional to particle diameter. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VDR-4XDKC9K-1&_user=6 [...] [article] Density based separations in the Reflux Classifier with an air–sand dense–medium and vibration [texte imprimé] / S. A. Macpherson, Auteur ; S. M. Iveson, Auteur ; K. P. Galvin, Auteur . - pp. 74-82. Génie Minier Métallurgie Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 2 (Janvier 2010) . - pp. 74-82 Mots-clés : Dense  medium  separation  Gravity  concentration  Coal Index. décimale : 622 Industrie minière Résumé : The Reflux Classifier is a device consisting of parallel inclined channels above a fluidized bed. Water-based versions of the system have been successfully employed in industry for gravity separation of −2 + 0.25 mm coal and mineral matter. In this study an air-fluidized system was investigated using a single 2 m long inclined channel with 100 mm wide channels and 20 mm perpendicular spacing. Sand (−355 + 125 micron) was used as a dense–medium and vibration at two distinct levels was used to improve fluidization stability. Tracer particles of −6.35 + 1.00 mm nominal diameter and 1300 to 2400 kg/m3 density were used to study the effects of the vibration energy and vibration direction on the separation efficiency. The device was able to separate coal particles from a maximum of 8 mm down to 1 mm on the basis of density; hence this method has potential for industrial application. Results were analysed using a simple 2-parameter dispersion–convection model. Dense particles had negative slip velocities, low-density particles had positive slip velocities and the slip velocities were proportional to particle diameter. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VDR-4XDKC9K-1&_user=6 [...]

Gravity separation of coarse particles using the Reflux Classifier / K. P. Galvin in Minerals engineering, Vol. 23 N° 4 (Mars 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 4 (Mars 2010) . - pp. 339–349 Titre : Gravity separation of coarse particles using the Reflux Classifier Type de document : texte imprimé Auteurs : K. P. Galvin, Auteur ; A.M. Callen, Auteur ; S. Spear, Auteur Année de publication : 2011 Article en page(s) : pp. 339–349 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Coal  preparation  Gravity  concentration  Separation  Fluidization  Particle  Sedimentation  Inclined  sedimentation  Coal  Elutriation  Oxide  ores  Diamonds Résumé : A comprehensive study examining the potential of the Reflux Classifier to be applied to the beneficiation of coarser coal up to 8 mm in size was undertaken. It was demonstrated that efficient combustible recovery and control of the separation density to target low ash products could be achieved. The major finding from the study was the critical importance of providing sufficient fluidization water, though beyond the critical level the process was largely insensitive to the fluidization rate. It was concluded the required fluidization velocity is nominally 10 m/h per mm of top-size, hence for a nominal 4 mm top size the required velocity is 40 m/h. In an extended campaign the control of the process was investigated by varying the set point density from high to low levels and then returning the process to the original settings, and demonstrating a return to the original separation. Further analysis was conducted to determine the partition curves and the shift in the separation density with particle size. The variation in the D50 with particle size approaches a level that is independent of the particle size. Previous data ( [Galvin et al., 2002] and [Galvin et al., 2004]) covering particles up to 2 mm in size are consistent with the results from this study, involving feeds with top sizes of 4 mm and 8 mm. Beyond a particle size of 2 mm the Ep is typically less than 0.05 and approaches about 0.03 as the particle size increases to 8 mm. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509002398 [article] Gravity separation of coarse particles using the Reflux Classifier [texte imprimé] / K. P. Galvin, Auteur ; A.M. Callen, Auteur ; S. Spear, Auteur . - 2011 . - pp. 339–349. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 4 (Mars 2010) . - pp. 339–349 Mots-clés : Coal  preparation  Gravity  concentration  Separation  Fluidization  Particle  Sedimentation  Inclined  sedimentation  Coal  Elutriation  Oxide  ores  Diamonds Résumé : A comprehensive study examining the potential of the Reflux Classifier to be applied to the beneficiation of coarser coal up to 8 mm in size was undertaken. It was demonstrated that efficient combustible recovery and control of the separation density to target low ash products could be achieved. The major finding from the study was the critical importance of providing sufficient fluidization water, though beyond the critical level the process was largely insensitive to the fluidization rate. It was concluded the required fluidization velocity is nominally 10 m/h per mm of top-size, hence for a nominal 4 mm top size the required velocity is 40 m/h. In an extended campaign the control of the process was investigated by varying the set point density from high to low levels and then returning the process to the original settings, and demonstrating a return to the original separation. Further analysis was conducted to determine the partition curves and the shift in the separation density with particle size. The variation in the D50 with particle size approaches a level that is independent of the particle size. Previous data ( [Galvin et al., 2002] and [Galvin et al., 2004]) covering particles up to 2 mm in size are consistent with the results from this study, involving feeds with top sizes of 4 mm and 8 mm. Beyond a particle size of 2 mm the Ep is typically less than 0.05 and approaches about 0.03 as the particle size increases to 8 mm. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509002398