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Natural convection mass transfer behavior of fixed bed of spheres in relation to catalytic and electrochemical reactor design / Ibrahim Hassan in Industrial & engineering chemistry research, Vol. 48 N° 7 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3692–3695 Titre : Natural convection mass transfer behavior of fixed bed of spheres in relation to catalytic and electrochemical reactor design Type de document : texte imprimé Auteurs : Ibrahim Hassan, Auteur ; Inderjit Nirdosh, Auteur ; Gomaa H. Sedahmed, Auteur Année de publication : 2009 Article en page(s) : pp. 3692–3695 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Convection  mass  transfer  Spheres  Electrochemical  reactor Résumé : The free convection mass transfer behavior of a fixed bed of spheres has been studied experimentally using an electrochemical technique which involved measuring the limiting current of the cathodic deposition of copper from acidified copper sulfate solution. Variables studied were sphere diameter, bed height, and physical properties of the solution. The mass transfer coefficient was found to decrease slightly with increasing bed height and independent of sphere diameter. The data were correlated for the conditions 5 × 106 < Sc·Gr < 5.4 × 108 by the equation Sh = 0.28(Sc·Gr)0.32. A comparison between the present and some previous data at other packing geometries shows that the rate of natural convection mass transfer at a bed of spheres is higher than that at beds of Raschig rings and at cylinders. The importance of the present results for the design and operation of catalytic and electrochemical reactors used to conduct diffusion controlled liquid−solid reactions is highlighted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801195b [article] Natural convection mass transfer behavior of fixed bed of spheres in relation to catalytic and electrochemical reactor design [texte imprimé] / Ibrahim Hassan, Auteur ; Inderjit Nirdosh, Auteur ; Gomaa H. Sedahmed, Auteur . - 2009 . - pp. 3692–3695. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3692–3695 Mots-clés : Convection  mass  transfer  Spheres  Electrochemical  reactor Résumé : The free convection mass transfer behavior of a fixed bed of spheres has been studied experimentally using an electrochemical technique which involved measuring the limiting current of the cathodic deposition of copper from acidified copper sulfate solution. Variables studied were sphere diameter, bed height, and physical properties of the solution. The mass transfer coefficient was found to decrease slightly with increasing bed height and independent of sphere diameter. The data were correlated for the conditions 5 × 106 < Sc·Gr < 5.4 × 108 by the equation Sh = 0.28(Sc·Gr)0.32. A comparison between the present and some previous data at other packing geometries shows that the rate of natural convection mass transfer at a bed of spheres is higher than that at beds of Raschig rings and at cylinders. The importance of the present results for the design and operation of catalytic and electrochemical reactors used to conduct diffusion controlled liquid−solid reactions is highlighted. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801195b

Sphalerite flotation using an arylhydroxamic acid collector / Daniel Hamilton in Industrial & engineering chemistry research, Vol. 48 N° 12 (Juin 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5584–5589 Titre : Sphalerite flotation using an arylhydroxamic acid collector : improving grade while using a reduced amount of copper sulfate for activation Type de document : texte imprimé Auteurs : Daniel Hamilton, Auteur ; Ramanathan Natarajan, Auteur ; Inderjit Nirdosh, Auteur Année de publication : 2009 Article en page(s) : pp. 5584–5589 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : N-Hydrocinnamoyl-N-phenylhydroxylamine  Float  sphalerite  Copper  sulfate  activation Résumé : N-Hydrocinnamoyl-N-phenylhydroxylamine (HCNPHA) was determined to float sphalerite without copper sulfate activation. However, the concomitant flotation of sulfidic (pyrite) and nonsulfidic gangue (silica) minerals significantly reduced the grade of the float concentrate. The addition of only 200 g/t copper sulfate, which is ∼20% of that which is being used currently in the xanthate reagent scheme, improved the grade and the recovery. Seven different types of carboxymethylcellulose (CMC-1−CMC-7) were tested. CMC-1 was found to be the best as a depressant of gangue flotation. Copper sulfate appeared to differentiate the sphalerite surface well and facilitated chelation while the CMC changed the frothing characteristics of the slurry and prevented entrainment of gangue into float concentrate (froth). Studies on flotation kinetics also confirmed the improved selectivity attained by using copper sulfate and a CMC. The selectivity index (SI) for sphalerite, with respect to pyrite, improved from 0.88 to 2.35 when copper sulfate was added, and that for nonsulfidic gangue increased from 1.93 to 6.29 when CMC was added. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900305r [article] Sphalerite flotation using an arylhydroxamic acid collector : improving grade while using a reduced amount of copper sulfate for activation [texte imprimé] / Daniel Hamilton, Auteur ; Ramanathan Natarajan, Auteur ; Inderjit Nirdosh, Auteur . - 2009 . - pp. 5584–5589. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5584–5589 Mots-clés : N-Hydrocinnamoyl-N-phenylhydroxylamine  Float  sphalerite  Copper  sulfate  activation Résumé : N-Hydrocinnamoyl-N-phenylhydroxylamine (HCNPHA) was determined to float sphalerite without copper sulfate activation. However, the concomitant flotation of sulfidic (pyrite) and nonsulfidic gangue (silica) minerals significantly reduced the grade of the float concentrate. The addition of only 200 g/t copper sulfate, which is ∼20% of that which is being used currently in the xanthate reagent scheme, improved the grade and the recovery. Seven different types of carboxymethylcellulose (CMC-1−CMC-7) were tested. CMC-1 was found to be the best as a depressant of gangue flotation. Copper sulfate appeared to differentiate the sphalerite surface well and facilitated chelation while the CMC changed the frothing characteristics of the slurry and prevented entrainment of gangue into float concentrate (froth). Studies on flotation kinetics also confirmed the improved selectivity attained by using copper sulfate and a CMC. The selectivity index (SI) for sphalerite, with respect to pyrite, improved from 0.88 to 2.35 when copper sulfate was added, and that for nonsulfidic gangue increased from 1.93 to 6.29 when CMC was added. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900305r