Documents disponibles écrits par cet auteur

Flotation bank air addition and distribution for optimal performance / C.D. Smith in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1023–1029 Titre : Flotation bank air addition and distribution for optimal performance Type de document : texte imprimé Auteurs : C.D. Smith, Auteur ; K. Hadler, Auteur ; J. J. Cilliers, Auteur Année de publication : 2011 Article en page(s) : pp. 1023–1029 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Mineral  processing  Froth  flotation  Air  profiling  Air  recovery  Optimisation Résumé : Recent studies have shown that varying the distribution of a set volume of air to a flotation bank significantly affects the performance of the bank. To date, however, the volume of air to be distributed has usually been arbitrarily set as that added with the ‘as found’ air rates, the typical operating air rates; not necessarily an optimum. Studies examining the effect of different total air additions, at a constant distribution, have shown the addition maximising air recovery typically yields the best performance. Air recovery is the fraction of the air added to a cell which overflows the lip of the cell as unburst bubbles and shows a peak with respect to cell aeration. In this work three experimental case studies are presented to examine of the role of aeration in flotation performance, with the aim of developing a generic technique to determine both the required total air addition and distribution of air to a bank of flotation cells. The first case study compares performance at three different total air additions. The air addition which gave the Peak Air Recovery (PAR) also gave the highest mineral recovery. Thus air recovery optimisation yields the optimum total air addition to a flotation bank. In the second case study the air recovery was optimised from each cell in a bank individually. The PAR air addition once more gave the highest mineral recovery from the bank. Therefore, air recovery optimisation determines the optimum total air addition to a bank and also provides a distribution for that air. The third case study compares a profile based on the PAR air rates with other distributions of the same total air. The results show the profile based on the PAR air rates gave a significantly higher cumulative mineral recovery than other distributions of the same volume of air, for the same cumulative grade. The results of the three case studies show air recovery optimisation of each cell in a bank is a robust and generic technique to simultaneously determine the optimum bank aeration and the optimum distribution of this air within the bank. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268751000124X [article] Flotation bank air addition and distribution for optimal performance [texte imprimé] / C.D. Smith, Auteur ; K. Hadler, Auteur ; J. J. Cilliers, Auteur . - 2011 . - pp. 1023–1029. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 1023–1029 Mots-clés : Mineral  processing  Froth  flotation  Air  profiling  Air  recovery  Optimisation Résumé : Recent studies have shown that varying the distribution of a set volume of air to a flotation bank significantly affects the performance of the bank. To date, however, the volume of air to be distributed has usually been arbitrarily set as that added with the ‘as found’ air rates, the typical operating air rates; not necessarily an optimum. Studies examining the effect of different total air additions, at a constant distribution, have shown the addition maximising air recovery typically yields the best performance. Air recovery is the fraction of the air added to a cell which overflows the lip of the cell as unburst bubbles and shows a peak with respect to cell aeration. In this work three experimental case studies are presented to examine of the role of aeration in flotation performance, with the aim of developing a generic technique to determine both the required total air addition and distribution of air to a bank of flotation cells. The first case study compares performance at three different total air additions. The air addition which gave the Peak Air Recovery (PAR) also gave the highest mineral recovery. Thus air recovery optimisation yields the optimum total air addition to a flotation bank. In the second case study the air recovery was optimised from each cell in a bank individually. The PAR air addition once more gave the highest mineral recovery from the bank. Therefore, air recovery optimisation determines the optimum total air addition to a bank and also provides a distribution for that air. The third case study compares a profile based on the PAR air rates with other distributions of the same total air. The results show the profile based on the PAR air rates gave a significantly higher cumulative mineral recovery than other distributions of the same volume of air, for the same cumulative grade. The results of the three case studies show air recovery optimisation of each cell in a bank is a robust and generic technique to simultaneously determine the optimum bank aeration and the optimum distribution of this air within the bank. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268751000124X

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

Recovery vs. mass pull / K. Hadler in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 994–1002 Titre : Recovery vs. mass pull : The link to air recovery Type de document : texte imprimé Auteurs : K. Hadler, Auteur ; C.D. Smith, Auteur ; J. J. Cilliers, Auteur Année de publication : 2011 Article en page(s) : pp. 994–1002 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  froths  Froth  flotation  Flotation  bubbles  Process  optimisation Résumé : In recent years, developments in control strategy for banks of flotation cells have included process control based on mass pull. Mass pull, or the flowrate of solids reporting to the concentrate, is affected by changes in froth structure and stability which are in turn affected by changes in operating parameters such as air flowrate and froth depth. Air recovery, or the fraction of air entering a cell that overflows the lip as unburst bubbles, is a robust, non-intrusive measure of froth stability that passes through a peak as cell air rate is increased. Furthermore, it has been shown that when operating a cell at the air rate that yields the ‘Peak Air Recovery’ (PAR), an improvement in flotation performance, particularly mineral recovery, can be obtained. In this paper, results from industrial experiments are reported that compare the effect of air rate on air recovery and flotation performance, and specifically the effect on mass pull and mineral recovery. The results show that an increase in mass pull does not necessarily yield an increased mineral recovery in all cases, since it is dependent on whether the air rate must be increased or decreased to obtain the ‘Peak Air Recovery’. This work shows the potential gain to be made from control using air recovery measurements and operating at PAR conditions. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001159 [article] Recovery vs. mass pull : The link to air recovery [texte imprimé] / K. Hadler, Auteur ; C.D. Smith, Auteur ; J. J. Cilliers, Auteur . - 2011 . - pp. 994–1002. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 994–1002 Mots-clés : Flotation  froths  Froth  flotation  Flotation  bubbles  Process  optimisation Résumé : In recent years, developments in control strategy for banks of flotation cells have included process control based on mass pull. Mass pull, or the flowrate of solids reporting to the concentrate, is affected by changes in froth structure and stability which are in turn affected by changes in operating parameters such as air flowrate and froth depth. Air recovery, or the fraction of air entering a cell that overflows the lip as unburst bubbles, is a robust, non-intrusive measure of froth stability that passes through a peak as cell air rate is increased. Furthermore, it has been shown that when operating a cell at the air rate that yields the ‘Peak Air Recovery’ (PAR), an improvement in flotation performance, particularly mineral recovery, can be obtained. In this paper, results from industrial experiments are reported that compare the effect of air rate on air recovery and flotation performance, and specifically the effect on mass pull and mineral recovery. The results show that an increase in mass pull does not necessarily yield an increased mineral recovery in all cases, since it is dependent on whether the air rate must be increased or decreased to obtain the ‘Peak Air Recovery’. This work shows the potential gain to be made from control using air recovery measurements and operating at PAR conditions. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510001159

The effects of hydrophobicity and orientation of cubic particles on the stability of thin films / G. Morris in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 979–984 Titre : The effects of hydrophobicity and orientation of cubic particles on the stability of thin films Type de document : texte imprimé Auteurs : G. Morris, Auteur ; S.J. Neethling, Auteur ; J. J. Cilliers, Auteur Année de publication : 2011 Article en page(s) : pp. 979–984 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  froths  Froth  flotation  Modelling  Simulation Résumé : A three-dimensional model of a single cubic particle in a thin liquid film has been developed using the Surface Evolver (Brakke, 1992) program. It has been used to investigate the effect of a particle’s contact angle on its energetically stable orientations at a liquid–vapour interface and how these, in turn, affect the particle’s ability to stabilise a thin film. It has been found that depending on the contact angle there are two possible stable orientations for a cubic particle (termed horizontal and rotated) at a liquid–vapour interface. For a film containing a cubic particle in a rotated orientation it has been found that the capillary pressure required to rupture the film is roughly 30% of that required for a film containing a particle of the same contact angle but in a horizontal orientation. The probability of a particle adopting one orientation over another is also investigated, showing that this too is affected by contact angle and leading to the conclusion that contact angle has a profound effect on non-spherical particles behaviour in thin films. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000956 [article] The effects of hydrophobicity and orientation of cubic particles on the stability of thin films [texte imprimé] / G. Morris, Auteur ; S.J. Neethling, Auteur ; J. J. Cilliers, Auteur . - 2011 . - pp. 979–984. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 979–984 Mots-clés : Flotation  froths  Froth  flotation  Modelling  Simulation Résumé : A three-dimensional model of a single cubic particle in a thin liquid film has been developed using the Surface Evolver (Brakke, 1992) program. It has been used to investigate the effect of a particle’s contact angle on its energetically stable orientations at a liquid–vapour interface and how these, in turn, affect the particle’s ability to stabilise a thin film. It has been found that depending on the contact angle there are two possible stable orientations for a cubic particle (termed horizontal and rotated) at a liquid–vapour interface. For a film containing a cubic particle in a rotated orientation it has been found that the capillary pressure required to rupture the film is roughly 30% of that required for a film containing a particle of the same contact angle but in a horizontal orientation. The probability of a particle adopting one orientation over another is also investigated, showing that this too is affected by contact angle and leading to the conclusion that contact angle has a profound effect on non-spherical particles behaviour in thin films. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000956

The relationship between the peak in air recovery and flotation bank performance / K. Hadler in Minerals engineering, Vol. 22 N° 5 (Avril 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 5 (Avril 2009) . - pp. 451–455 Titre : The relationship between the peak in air recovery and flotation bank performance Type de document : texte imprimé Auteurs : K. Hadler, Auteur ; J. J. Cilliers, Auteur Année de publication : 2009 Article en page(s) : pp. 451–455 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Froth  flotation  Flotation  bubbles  Flotation  froths  Air  recovery  Air  profiling Résumé : Air recovery, or the fraction of air entering a cell that overflows the cell lip as unburst bubbles, is an important measure of froth stability as it affects the flow of bubble surface to the concentrate. An experimental campaign was carried out over the first four cells of the rougher bank at a South African platinum mine in order to find the relationship between froth stability and flotation performance as a function of air flowrate. The results showed that a peak in air recovery was observed as the air rate increased. Furthermore, this corresponded to the air flowrate at which the highest overall recovery was obtained. This can be explained by understanding the resulting changes in the structural features of the froth such as bubble loading and the flow of bubble surface and suggests that improved flotation performance can be achieved by operating a bank under conditions that result in a maximum in froth stability. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268750800280X [article] The relationship between the peak in air recovery and flotation bank performance [texte imprimé] / K. Hadler, Auteur ; J. J. Cilliers, Auteur . - 2009 . - pp. 451–455. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 5 (Avril 2009) . - pp. 451–455 Mots-clés : Froth  flotation  Flotation  bubbles  Flotation  froths  Air  recovery  Air  profiling Résumé : Air recovery, or the fraction of air entering a cell that overflows the cell lip as unburst bubbles, is an important measure of froth stability as it affects the flow of bubble surface to the concentrate. An experimental campaign was carried out over the first four cells of the rougher bank at a South African platinum mine in order to find the relationship between froth stability and flotation performance as a function of air flowrate. The results showed that a peak in air recovery was observed as the air rate increased. Furthermore, this corresponded to the air flowrate at which the highest overall recovery was obtained. This can be explained by understanding the resulting changes in the structural features of the froth such as bubble loading and the flow of bubble surface and suggests that improved flotation performance can be achieved by operating a bank under conditions that result in a maximum in froth stability. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S089268750800280X