The role of the pulp-froth interface on particle detachment and selectivity

Chipili, Chitalu; Bhondayi, C.

doi:10.1016/j.cis.2020.102296

Cited by 15 publications

(6 citation statements)

References 100 publications

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“…The pulp-froth interface is a region transitioning from the bubbly flow zone of the pulp, with low bubble density, to the froth, with high packing fraction for bubbles. Previous works, such as a recent review by Chipili and Bhondayi [50], have highlighted that coarser particles are more likely to detach at the interface [51] and the energy of the particle from the fluid imparted by the impeller is likely absorbed to be in the deformation of the bubble film or structural changes such as coalescence and topological rearrangements [52]. It is plausible that the hydrophobic particle repeatedly detached and reattached in this region, and once it had moved past the turbulent interface region, was entrained or even entrapped between bubbles as opposed to attached.…”

Section: Hydrodynamic Profiles: Azimuthal Slicesmentioning

confidence: 99%

Characterisation of solid hydrodynamics in a three-phase stirred tank reactor with positron emission particle tracking (PEPT)

Cole

Brito-Parada

Hadler

et al. 2022

Chemical Engineering Journal

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Section: Hydrodynamic Profiles: Azimuthal Slicesmentioning

confidence: 99%

Characterisation of solid hydrodynamics in a three-phase stirred tank reactor with positron emission particle tracking (PEPT)

Cole

Brito-Parada

Hadler

et al. 2022

Chemical Engineering Journal

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“…This observation could be explained by the inertia of small particles, which is not enough to permit them to penetrate the film formed by the laminar fluid flow around the bubble and form a particle-bubble aggregate (Miettinen et al 2010). Less disruptive forces within the cell allow particles to attach to the bubble at lower impeller tip speeds since the film formed around the bubble is not as resistant to penetration by a moving particle (Chipili and Bhondayi 2021;Nguyen and Evans 2004). Furthermore, smaller particles that attach to a bubble are more likely to have a higher probability of reaching the surface than coarse particles (Zhang and Subasinghe 2016).…”

Section: Particle Size Distribution Analysesmentioning

confidence: 99%

Influence of hydrodynamic variables on scaling up of mechanical flotation cells

et al. 2022

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Flotation performance is influenced by many hydrodynamic variables, such as impeller speed, airflow rate, and cell geometry. These variables’ effects and interactions remain unsatisfactorily explored, especially concerning scaling-up procedures. As an innovative approach, this study considered factorial-designed experiments to explore the effects of hydrodynamic factors (impeller tip speed and superficial gas velocity) on scaling up the Outotec GTK LabCell™ mechanical flotation machine cells, common equipment used as a benchmark for many industrial pre-feasibility studies. Therefore, the influence of hydrodynamic variables and their interactions on flotation performance was evaluated in two cells (2 L and 7.5 L). The evaluation was based on the flotation rate constant “k” calculated by first- and second-order equations. Analysis of the particle size distribution indicated that the performance of the two cells was different, as shown by the finer concentrate for the 2-L cell compared to the 7.5-L cell. The outcomes demonstrated that symmetrical design in the geometry of mechanical flotation cells would lead to an accurate scaling up based on the metallurgical responses. Otherwise, the scaling procedure could only be accurate under some specific conditions. As a criterion, the results showed that using k, the scaling-up process between these two GTK LabCell™ mechanical flotation machine cells (2 L and 7.5 L) would be possible only under a specific superficial gas velocity (0.14 cm/s) apart from the impeller tip speed (R2 = 1). These results could potentially be key for the future design and development of mechanical flotation cells.

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“…Last, the mechanism of bubble-particle collision detachment with varying hydrophobicity and sizes was investigated by analyzing particle trajectory and velocity, bubble velocity, and projected area by using MATLAB software. A thorough comprehension of the phase interface collision detachment mechanism is essential for enhancing the flotation process’s bubble-particle detachment mechanism and serving as a roadmap for increasing the maximum flotation particle size …”

Section: Introductionmentioning

confidence: 99%

Effect of Particle Size and Hydrophobicity on Bubble-Particle Collision Detachment at the Slurry–Foam Phase Interface

Zhang,

Ding,

et al. 2024

ACS Omega

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The slurry phase, foam phase, and slurry−foam phase interfaces are the typical locations for bubble-particle detachment, and significant advancements have been achieved in the detachment theory of the slurry phase and foam phase. However, the microscopic detachment mechanism of particles at the slurry−foam phase interface is still unclear. Specifically, there is still debate concerning the collision detachment mechanism of bubble-particle aggregates. Thus, this work investigated the effects of particle size and hydrophobicity on bubble-particle collision detachment. First, a tensiometer detected the detachment force between particles and bubbles. Next, using a high-speed dynamic camera, the collision detachment probability and detachment behavior of bubble-particle aggregates at the interface (solid surface) were statistically recorded and captured. Last, MATLAB software was used to analyze the trajectory and velocity of the particles and the velocity and projected area of the bubbles in the process of bubble-particle collision detachment. This allows for a deeper investigation of the mechanism underlying the detachment of particles of various sizes and hydrophobicity. It is discovered that as particle hydrophobicity increases, the probability of bubbleparticle collision detachment reduces. This is because when particle hydrophobicity increases, so does the interaction force between particles and bubbles, improving the stability of the bubble-particle aggregates. Simultaneously, it is discovered that there are notable differences in the collision detachment mechanisms of various particle sizes. Due to their low gravity, the fine particles in the bubbleparticle aggregate will slide down the bubble's surface when it collides with the solid surface. This differential velocity motion between the particle and the bubble plays a significant role in the fine particles' detachment. However, the gravity of the coarse particles is strong enough to squeeze the bubbles vertically, and bubble oscillation is an important reason for the detachment of the bubble-particle aggregates. The study's findings advance our understanding of the bubble-particle collision detachment mechanism and offer a theoretical direction for investigating collision detachment behavior at the real slurry−foam phase interface.

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The role of the pulp-froth interface on particle detachment and selectivity

Cited by 15 publications

References 100 publications

Characterisation of solid hydrodynamics in a three-phase stirred tank reactor with positron emission particle tracking (PEPT)

Characterisation of solid hydrodynamics in a three-phase stirred tank reactor with positron emission particle tracking (PEPT)

Influence of hydrodynamic variables on scaling up of mechanical flotation cells

Effect of Particle Size and Hydrophobicity on Bubble-Particle Collision Detachment at the Slurry–Foam Phase Interface

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