Estimation of Bubble Diameter in Flotation Columns from Drift Flux Analysis

Dobby, G.S.; Yianatos, J.; Finch, J.A.

doi:10.1179/cmq.1988.27.2.85

Cited by 68 publications

(19 citation statements)

References 9 publications

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“…Substituting equation (4) into equation (5) results in another familiar expression for the bubble rise velocity Uba given as Uba = Qg/(Accg) = Jg/Cg. (6) This is also equal to the average velocity of gas in the column. Nicklin [19] experimentally verified equations (1) and (6), by directly measuring average bubble rise velocity, bubble drift velocity and gas holdup in a stagnant liquid.…”

Section: Theorymentioning

confidence: 98%

“…This is mainly due to the fact that in the case of an ensemble of bubbles, the distribution of velocities, temperatures, and concentrations in the vicinity of one bubble are influenced by its neighbors [12]. The flow characterization of bubble columns has been investigated extensively [5,6,[12][13][14][15][16][17][18][19]. However, the effects of different surfactants at varied dosages on bubble rise velocities have not been considered in most of these investigations.…”

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confidence: 99%

“…Moreover, an agreement between the theoretical models, based on the above assumptions, and the experiment data was seldom obtained [2]. Due to the difficulties in evaluating the effect of the surface-active materials on bubble behavior, the bubbles in flotation systems are often treated as solid spheres, and the bubble rise velocities in a swarm are usually estimated either from models for solid sphere hindered settling velocities [1,[3][4][5][6][7], or by empirical expressions for single bubble systems [8,9].…”

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confidence: 99%

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Frother Effects on Bubble Motion in A Swarm

Zhou¹,

Egiebor²,

Plitt³

1993

Canadian Metallurgical Quarterly

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The effect of frothers on the average bubble rise velocity in bubble swarm systems was investigated. It is shown from this study that adding a frother has a drastic effect on bubble motion in a flotation column. In the absence of frothers, the average bubble rise velocity decreases with the increase of gas flowrate; while in the presence of frothers, the average bubble rise velocities either increase or decrease with the gas flowrate, depending on the frother type and concentration. The results also indicate that a higher gas holdup does not necessarily mean that a smaller size of bubble is produced in the column for different frother systems, due to the contamination factor effects on bubbles. Based on Marrucci's equation and Nicklin's work, an expression for the average bubble rise velocity in a swarm was established to relate to the bubble size; gas holdup, superficial gas and liquid velocities, and contamination factor, and found to agree well with the literature data and experimental measurements in Dowfroth 250 and MIBC solutions.Resume-L'effet d'agents moussants sur la vitesse moyenne d'ascension des bulles a ete etudie dans divers systemes d'ecume. Cette etude montre que l'addition d'agents moussants a un effet marque sur Ie mouvement des bulles dans une colonne de flottation. En l'absence d'agents moussants, la vitesse moyenne d'ascension des bulles decroit lorsqu'on augmente Ie debit gazeux; cependant, en presence d'agent moussant, la vitesse moyenne peut augmenter ou diminuer en fonction du debit gazeux, selon Ie type et la concentration de l'agent moussant. Les resultats indiquent egalement qu'une augmentation de la retention gazeuse n'est pas necessairement associee a la production de plus petites bulles dans la colonne, a cause des effets de contamination sur les bulles. A partir de l'equation de Marrucci et du travail de Nicklin, une expression a ete developpee afin de relier la vitesse moyenne d'ascension des bulles a leur grosseur, a la retention gazeuse, aux gaz superficiels, ala vitesse du liquide ainsi qu a un facteur de contamination. Cette expression semble en bon accord avec les donnees de la litterature et les mesures experiment ales dans les solutions contenant du Dowfroth 250 et MIBC.

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Section: Theorymentioning

confidence: 98%

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confidence: 99%

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confidence: 99%

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Frother Effects on Bubble Motion in A Swarm

Zhou¹,

Egiebor²,

Plitt³

1993

Canadian Metallurgical Quarterly

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“…. El Diámetro de burbuja, Db, se obtuvo mediante el procedimiento interactivo conocido como análisis de arrastre "Drift Flux" [11][12][13] , usando datos de gas retenido y velocidades relativas de fase, Jg y Jl. Cabe mencionar que este método provee datos globales del Dd, considerando un flujo homogéneo de burbujas en el equipo de flotación.…”

Section: Sb=unclassified

Cinética de separación de Cu (II) por técnicas de flotación iónica, en celdas con dispersores flexibles

Pérez¹,

Tavera²,

Escudero³

et al. 2010

REVMETAL

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ResumenEste estudio investiga y determina experimentalmente los parámetros cinéticos y el efecto de la modificación de las condiciones químicas e hidrodinámicas de las dispersiones aire-líquido, durante la separación de Cu (II) mediante téc-nicas de flotación iónica en celdas con dispersores porosos. Los resultados muestran que la eliminación de Cu (II) de la solución se puede llevar acabo por flotación iónica en una etapa, con 68 y 56 % de recuperación y una concentración de xantato de 0,02 g/l, para los difusores de burbujas cilíndrico y plano, respectivamente. En sistemas multi etapas cinco celdas, se lograron recuperaciones superiores al 92 % para ambas geometrías de dispersión. La constante cinética de flotación aparente mantiene un comportamiento lineal con los parámetros que caracterizan una dispersión (Jg, e g y Db), hasta un punto donde la inestabilidad del proceso vuelve inoperable el sistema. Los resultados muestran que la remoción de iones de metal base por técnicas de flotación iónica se ve fuertemente afectado por los factores: concentración de colector [C], Jg, eg, Db, Jl y Sb. Palabras claveCinética; Flotación iónica; Cobre; Celdas; Gas retenido. Kinetics of Cu (II) separation by ion flotation techniques, in cells with flexible spargers AbstractThis research studies and experimentally determines the kinetic parameters and effect of modifying the hydrodynamics and chemical conditions of the air-liquid dispersions during the Cu (II) extraction by ion flotation techniques in cells with porous spargers. Results show that the elimination of Cu (II) from solution can be carried out by ion flotation in one stage, obtaining efficiencies of 68% and 56% for the flat and cylindrical sparger respectively with a xanthate concentration of 0,02 g/l. In multistage systems five cells, recoveries over 92 % were achieved for both sparger geometries. The behavior of the flotation apparent kinetic constant is linear to the parameters that characterize dispersion (Jg, e g y Db), until a point is achieved where the process instability makes the system inoperable. The results show that removing base metal ions by ion flotation is strongly affected by the following factors: collector concentration [C], Jg, eg, Db, Jl and Sb.

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“…2) Dobby et al 3) and Yianatos et al 4) have attempted the estimation of bubble size in columns using drift flux analysis and the method of calculating the settling velocity of spherical particles as adopted by Concha 5) and hindered settling equations of Masliyah,1) respectively. These studies showed that the calculated mean bubble size is in the range 0.51.5 mm under typical superficial gas and liquid rates, and gas holdup measured in gas-water or gas-slurry systems.…”

Section: Introductionmentioning

confidence: 99%

Amenability Testing of Fine Coal Beneficiation Using Laboratory Flotation Column

2015

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The amenability of beneficiating a low rank coal has been studied using a laboratory CPT CoalPro flotation column. After review of the published literature various relationships between bubble size and superficial gas rate, bubble surface area flux and gas hold up and slip velocity and bubble size have been deduced in relation to the coal slurry and compared with relationships reported in the literature. A performance curve for the flotation column tested under the operating conditions revealed that the optimal size range of coal that yields optimal separation occurred in the size range 60200 microns. Empirical relationships a) to estimate the gas hold up in terms of the measurable quantities, such as superficial gas and water flow rates and frother concentration and b) to predict the carrying capacity of particles of various sizes into the concentrate have been developed. Based on grade/recovery plots, the optimal separation that can be achieved for the given coal in a flotation column was found to be 85% combustible recovery with 81% ash rejection at the separation efficiency of 62% along with the corresponding operating conditions. Empirical relationships to predict the recovery of combustibles and ash rejection in terms of operating variables have also been proposed.

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Estimation of Bubble Diameter in Flotation Columns from Drift Flux Analysis

Cited by 68 publications

References 9 publications

Frother Effects on Bubble Motion in A Swarm

Frother Effects on Bubble Motion in A Swarm

Cinética de separación de Cu (II) por técnicas de flotación iónica, en celdas con dispersores flexibles

Amenability Testing of Fine Coal Beneficiation Using Laboratory Flotation Column

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