Detachment of particles from bubbles in an agitated vessel

Goel, Suraj; Jameson, Graeme J.

doi:10.1016/j.mineng.2012.08.001

Cited by 63 publications

(26 citation statements)

References 15 publications

(23 reference statements)

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“…Schulze (1982) considered that the radius of the rotation is equal to the bubble's diameter, while Hui (2001) regarded the diameter of the bubble-particle aggregate as the rotation radius. Goel and Jameson (2012) considered that the bubble-particle aggregate was captured in the center of the eddy and that the radius of rotation was the bubble's radius. Theoretically, when the attached particles are negligible to the bubble or if the bubble is fully covered by tiny particles, where the bubble is considered to be a heavier bubble but much lighter than the fluid phase, the aggregate will act more like a bubble.…”

Section: Summary Of Discussionmentioning

confidence: 99%

“…The testing of particle detachment as a function of the energy dissipation rate in a turbulent liquid field is only recently available (Goel and Jameson 2012). As shown in Figure 8, a specially designed flotation cell was devised to observe the behavior of particle-laden bubbles in a turbulent shear flow, where Schulze's hypothesis and the criterion for detachment are tested.…”

Section: Experimental Workmentioning

confidence: 99%

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A review of the mechanisms and models of bubble-particle detachment in froth flotation

Wang

Nguyen

Mitra

et al. 2016

Separation and Purification Technology

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129

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Only when the process of particle detachment is well understood and modelled can minerals recovery using the flotation process be modulated to achieve a high efficiency by suitably changing the operating parameters. This is vitally necessary for the recovery of coarse particles in an energy efficient way, as detachment is the key limiting factor in the successful recovery of large particles. However, until the detachment mechanism is more fully understood, an upper limit on the floatable particle diameter still remains unidentified. To assess the current state of knowledge available in this area, a comprehensive literature review on the mechanisms and models of the bubble-particle detachment process in froth flotation is presented. In general, the detachment process is considered to be a stochastic process, and is usually attributed to the dynamic interactions with the turbulent flow structures (eddies) in the flotation environment which cause particles to detach because of dissipating energy. In this paper, previous studies on bubble-particle detachment have been critically analyzed with respect to the formulation of the models in predicting the detachment probability of particles. The models are classified into three different categories: force balance analysis; energy balance analysis and empirical analysis of particle size compared to maximum floatable particle size. Attention is also paid to an understanding of the mechanisms of bubble-particle detachment in quiescent and turbulent liquid flow fields. The predictions of all these models have been compared with the published experimental data and it was found that models which take an accurate consideration of the influence of eddies on a particle's detachment give the closest predictions. The generally held concept of bubble-particle detachment inside an eddy was experimentally validated, where a particle was observed to rotate on the surface of a bubble, resulting in a centrifugal acceleration 20 times that of gravitational acceleration. The aim of this paper is to review the developments and limitations of the existing models. The experimental work is reviewed so as to reveal the mechanisms of bubble-particle 3 detachment. Therefore, the future development of models is identified in order to successfully predict particle detachment.

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Section: Summary Of Discussionmentioning

confidence: 99%

Section: Experimental Workmentioning

confidence: 99%

A review of the mechanisms and models of bubble-particle detachment in froth flotation

Wang

Nguyen

Mitra

et al. 2016

Separation and Purification Technology

Self Cite

129

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show abstract

“…Knowing the tenacity of particle attachment then the efficiency of bubble-particle stability and detachment can be computed and then used to predict the maximum size of floatable particle (Pyke et al, 2003;Nguyen and Schulze, 2004;Jameson et al, 2007;Goel and Jameson, 2012). In addition to the particle weight, turbulence has a significant role in disrupting the bubble-particle aggregates.…”

Section: Effect Of Turbulence On Detachmentmentioning

confidence: 99%

A review of stochastic description of the turbulence effect on bubble-particle interactions in flotation

Nguyen

An-Vo

Tran-Cong

et al. 2016

International Journal of Mineral Processing

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Flotation in mechanically agitated cells has been the workhorse of the mining industry, but our quantitative understanding of the effect of microturbulence generated by agitation on flotation is still very limited. This paper aims to review the literature on quantifying the microturbulence effects on bubble-particle interactions in flotation. The particular focus is on the stochastic description of bubble-particle interactions in the turbulent flow which is a random field. We briefly review the stochastic description of microturbulence and motions of particles of micrometre sizes and bubbles of millimetre sizes in the isotropic turbulence of mechanical flotation cells. The key starting point is the generic equation of motion, which can be decomposed into the mean turbulent variables and fluctuating turbulent variables. The turbulent flow of the carrying liquid is characterised using isotropic turbulence theory. The next focus is on reviewing bubble-particle turbulent collision and detachment interactions. Bubble-particle turbulent collision is poorly quantified; no quantitative models of the bubble-particle turbulent collision efficiency relevant for flotation are available.Current theories on bubble-particle turbulent detachment face some deficiencies. In assessing the microturbulence effect on bubble-particle detachment, the majority of studies only consider the particle acceleration in the centrifugal direction but ignore the transverse acceleration of particles, which is due to turbulent shear flow. Critically, contact angle required in quantifying the detachment is not constant, single-valued as considered in the theories, but can vary from receding to advancing value during the relaxation of the triple contact line on the particle surface. The latest experiments show that multiple-valued contact angle can significant affect stability and detachment of floating particles. Finally, quantifying the microturbulence effect on flotation requires further research.

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“…An experimental study to validate the centrifugal bubble-particle detachment theory was carried out by Goel [85] in a specially designed agitated tank, shown in Figure 8. The experimental tank uses an impeller with a well-defined power input, operated with no froth phase, and was able to separately collect the detached particles from the feed and recovered overflow.…”

Section: Bubble-particle Detachment Studiesmentioning

confidence: 99%

“…Importantly, the problem to be solved is different here from previous methodologies [16,19,20,22,25] in that in this work, we consider the case for which the contact line is not pinned at a sharp edge and where the contact angle is not constrained as a constant. 85…”

Section: Figurementioning

confidence: 99%

Hydrodynamic forces on floating particles

Sherman¹

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Detachment of particles from bubbles in an agitated vessel

Cited by 63 publications

References 15 publications

A review of the mechanisms and models of bubble-particle detachment in froth flotation

A review of the mechanisms and models of bubble-particle detachment in froth flotation

A review of stochastic description of the turbulence effect on bubble-particle interactions in flotation

Hydrodynamic forces on floating particles

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