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Minerals
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Interactions between Bubbles and Solid Particles during the Flotation Process
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Interactions between Bubbles and Solid Particles during the Flotation Process

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (23 July 2021) | Viewed by 21058

Special Issue Editors

Dr. Pavlína Basařová

E-Mail Website
Guest Editor
Department of Chemical Engineering, University of Chemistry and Technology Prague, Technická 3, 166 28 Prague, Czech Republic
Interests: multiphase flows; bubble behaviour; surface phenomena; complex fluid; flotation
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Vladimír Čablík

E-Mail Website1 Website2
Guest Editor
VŠB—Technical University of Ostrava, Department of Environmental Engineering and Institute of Clean Technologies for Extraction and Utilization of Energy Resources, 708 00 Ostrava-Poruba, Czech Republic
Interests: flotation; column flotation; mineral processing; waste management

Special Issue Information

Dear Colleagues,

The interaction between bubbles and solid particles is an important mechanism in many industrial processes; flotation is one of the most widely used applications in these domains. Today, flotation is used not only to separate coal or mineral particles from mined ore deposits, but also to separate plastic materials, wastewater treatment or paper recycling. The overall flotation efficiency is given as the combination of collision efficiency and attachment efficiency, which is influenced by the formation and expansion of the three-phase contact line, solid particle properties, bubble size and dynamics, or by the presence of flotation agents, particularly surface-active agents. We warmly invite you to contribute to this Special Issue, entitled “Interactions between Bubbles and Solid Particles during the Flotation Process”.

Given the scientific scope of Minerals, the topics of interest of this Special Issue include original papers related to basic and applied research on the physicochemical aspects of the flotation separation process, such as experimental or calculated flotation efficiency, three-phase contact line formation and expansion, the stability of bubble-particle aggregates, flotation kinetics, the attachment mechanism, and the influence of flotation agents.

Prof. Dr. Pavlína Basařová
Prof. Dr. Vladimír Čablík
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • flotation
  • bubble-particle interaction
  • bubble attachment
  • particle attachment
  • three-phase contact line
  • flotation efficiency
  • flotation kinetics
  • flotation agents

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Published Papers (6 papers)

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Research

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13 pages, 1506 KiB  
Article
Effect of Fluoride Ion on the Separation of Fluorite from Calcite Using Flotation with Acidified Water Glass
by Daqian Wang, Dan Liu, Yingbo Mao, Ruofan Sun, Ruitao Liu and Shuming Wen
Minerals 2021, 11(11), 1203; https://doi.org/10.3390/min11111203 - 28 Oct 2021
Cited by 6 | Viewed by 2458
Abstract
As a common depressant, acidified water glass (AWG) has strong inhibitory effects on fluorite and calcite. The inhibited fluorite is difficult to be recovered, thus resulting in the waste of resources and low flotation efficiency. In this study, the interaction of fluoride ions [...] Read more.
As a common depressant, acidified water glass (AWG) has strong inhibitory effects on fluorite and calcite. The inhibited fluorite is difficult to be recovered, thus resulting in the waste of resources and low flotation efficiency. In this study, the interaction of fluoride ions with fluorite and calcite surfaces was investigated, and its effects of AWG adsorption on mineral surfaces were evaluated. Micro-flotation experiments indicated that the flotation recovery of fluorite is 88.72% after fluoride ion treatment, that is, approximately fourfold with respect to that without fluoride ion modification. The results of solution chemical calculations showed that SiO(OH)3− is the main component to inhibit fluorite, and Si(OH)4 is the main component to inhibit calcite in AWG solution. XPS and ICP-MS results showed that fluoride ions can improve the floatability of fluorite by converting CaSiO3 on the surface of fluorite into CaF2, but the conversion ability of Si(OH)4 on the surface of calcite is weak, which increases the difference in floatability between fluorite and calcite. The above results were further verified by the analysis of flotation foam image and contact angle measurement. After fluorine ion treatment, the contact angle of fluorite increased, and it was more easily adsorbed on the foam. Therefore, the interaction of the fluoride ion with the fluorite surfaces eliminated the adsorption of AWG on fluorite, thereby resulting in the enhanced hydrophobicity of fluorite. Different from the traditional metal ions modification, the idea of anion modification in this paper is expected to be further studied. Full article
(This article belongs to the Special Issue Interactions between Bubbles and Solid Particles during the Flotation Process)
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13 pages, 4238 KiB  
Article
Influence of Microbubble on Fine Wolframite Flotation
by Penggang Wei, Liuyi Ren, Yimin Zhang and Shenxu Bao
Minerals 2021, 11(10), 1079; https://doi.org/10.3390/min11101079 - 30 Sep 2021
Cited by 13 | Viewed by 1997
Abstract
The recovery of fine wolframite is low when using traditional flotation that does not use a microbubble. In this study, a microbubble was introduced into the fine wolframite flotation system; −20 μm wolframite was used as an experiment sample and octyl hydroxamic acid [...] Read more.
The recovery of fine wolframite is low when using traditional flotation that does not use a microbubble. In this study, a microbubble was introduced into the fine wolframite flotation system; −20 μm wolframite was used as an experiment sample and octyl hydroxamic acid as the collector. The recovery of microbubble flotation reached 84.07%, which is about 12.04% higher than that of traditional flotation. A single-factor flotation experiment, high-speed camera analysis, and SEM (Scanning Electron Microscopy) analysis were used to study the influence of microbubbles on the flotation of fine wolframite. The results show that fine wolframite will more easily agglomerate under the action of microbubbles. The octyl hydroxamic acid adsorbed on the surface of wolframite treated with microbubbles is denser and more abundant. Full article
(This article belongs to the Special Issue Interactions between Bubbles and Solid Particles during the Flotation Process)
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17 pages, 4689 KiB  
Article
Influence of Temperature on Rising Bubble Dynamics in Water and n-pentanol Solutions
by Mariusz Borkowski and Jan Zawala
Minerals 2021, 11(10), 1067; https://doi.org/10.3390/min11101067 - 29 Sep 2021
Cited by 7 | Viewed by 4018
Abstract
Data in the literature on the influence of water temperature on the terminal velocity of a single rising bubble are highly contradictory. Different variations in bubble velocity with temperature are reported even for potentially pure systems. This paper presents a systematic study on [...] Read more.
Data in the literature on the influence of water temperature on the terminal velocity of a single rising bubble are highly contradictory. Different variations in bubble velocity with temperature are reported even for potentially pure systems. This paper presents a systematic study on the influence of temperature between 5 °C and 45 °C on the motion of a single bubble of practically constant size (equivalent radius 0.74 ± 0.01 mm) rising in a clean water and n-pentanol solution of different concentrations. The bubble velocity was measured by a camera, an ultrasonic sensor reproduced in numerical simulations. Results obtained by image analysis (camera) were compared to the data measured by an ultrasonic sensor to reveal the similar scientific potential of the latter. It is shown that temperature has a significant effect on the velocity of the rising bubble. In pure liquid, this effect is caused only by modifying the physicochemical properties of the water phase, not by changing the hydrodynamic boundary conditions at the bubble surface. In the case of the solutions with surface-active substances, the temperature-change kinetics of the dynamic adsorption layer formation facilitate the immobilization of the liquid/gas interface. Full article
(This article belongs to the Special Issue Interactions between Bubbles and Solid Particles during the Flotation Process)
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15 pages, 2275 KiB  
Article
Comparison of Two Solvers for Simulation of Single Bubble Rising Dynamics: COMSOL vs. Fluent
by Jakub Crha, Pavlína Basařová, Marek C. Ruzicka, Ondřej Kašpar and Maria Zednikova
Minerals 2021, 11(5), 452; https://doi.org/10.3390/min11050452 - 25 Apr 2021
Cited by 6 | Viewed by 6472
Abstract
Multiphase flows are a part of many industrial processes, where the bubble motion influences the hydrodynamic behavior of the batch. The current trend is to use numerical solvers that can simulate the movement and mutual interactions of bubbles. The aim of this work [...] Read more.
Multiphase flows are a part of many industrial processes, where the bubble motion influences the hydrodynamic behavior of the batch. The current trend is to use numerical solvers that can simulate the movement and mutual interactions of bubbles. The aim of this work was to study how two commercial CFD solvers, COMSOL Multiphysics and Ansys Fluent, can simulate the motion of a single rising bubble in a stagnant liquid. Simulations were performed for spherical or slightly deformed bubbles (Db = 0.6, 0.8, and 1.5 mm) rising in water or in propanol. A simple 2D axisymmetric approach was used. Calculated bubble terminal velocities and bubble shape deformations were compared to both experimental data and theoretical estimations. Solver Comsol Multiphysics was able to precisely calculate the movement of smaller and larger bubbles; due to the 2D rotational symmetry, better results were obtained for small spherical bubbles. The deformation of larger bubbles was calculated sufficiently. Solver Ansys Fluent, in the setting used, failed to simulate the motion of small bubbles due to parasitic currents but allowed for modeling of the motion of larger bubbles. However, the description of the bubble velocity and shape was worse in comparison with experimental values. Full article
(This article belongs to the Special Issue Interactions between Bubbles and Solid Particles during the Flotation Process)
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13 pages, 18328 KiB  
Article
Collision of Bubbles with Solid Surface in the Presence of Specific Surfactants
by Maria Zednikova, Jakub Crha, Lucie Vobecká, Pavlína Basařová, Jiri Vejrazka and Jaroslav Tihon
Minerals 2021, 11(5), 442; https://doi.org/10.3390/min11050442 - 21 Apr 2021
Cited by 5 | Viewed by 2239
Abstract
The present work is motivated by the effort to understand basic processes occurring in three-phase systems where small bubbles interact with large particles. The simplified system of a single bubble rising in a stagnant liquid and colliding with a solid surface is studied. [...] Read more.
The present work is motivated by the effort to understand basic processes occurring in three-phase systems where small bubbles interact with large particles. The simplified system of a single bubble rising in a stagnant liquid and colliding with a solid surface is studied. The effect of two specific surfactants, α-Terpineol and n-Octanol, is investigated. Two independent measurements are combined: (i) bubble–solid surface collision experiments and (ii) the bubble shape oscillations induced by a movable capillary. Both experiments are based on high-speed imaging resulting in the evaluation of the restitution coefficient characterizing the collision process and the relative damping time characterizing the bubble shape oscillations in the presence of surfactants. It was observed that even for small concentrations of a surfactant, both the bubble shape oscillations and the bubble bouncing on the solid surface are significantly suppressed. Two predictions for the restitution coefficient are proposed. The equations include a term characterizing the suppression of the damping time in the presence of surfactants and a term balancing the inertia, capillary and viscous forces in the liquid film separating the bubble and the solid surface. The proposed equations successfully predict the restitution coefficient of bubble bouncing on the solid surface in liquids with the addition of specific surfactants. Full article
(This article belongs to the Special Issue Interactions between Bubbles and Solid Particles during the Flotation Process)
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Review

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12 pages, 4010 KiB  
Review
A Rational Interpretation of the Role of Turbulence in Particle-Bubble Interactions
by Ning Yao, Jingting Liu, Xun Sun, Yan Liu, Songying Chen and Guichao Wang
Minerals 2021, 11(9), 1006; https://doi.org/10.3390/min11091006 - 15 Sep 2021
Cited by 8 | Viewed by 2648
Abstract
Interactions between particles and bubbles have been cornerstone for the successful applications of froth flotation to the beneficiations of minerals or coal. Particle-bubble interactions are highly physio-chemical processes on the basis of surface science and hydrodynamics. Though these two aspects are deeply interwoven, [...] Read more.
Interactions between particles and bubbles have been cornerstone for the successful applications of froth flotation to the beneficiations of minerals or coal. Particle-bubble interactions are highly physio-chemical processes on the basis of surface science and hydrodynamics. Though these two aspects are deeply interwoven, we focus on the discussions of the effects of turbulence on the interactions between particles and bubbles, i.e., collision, attachment and detachment. It has to be mentioned this effect is not working in one direction and can affect flotation performance in a complicated way. Only when turbulence effects are well understood, flotation processes can be optimised by suitably changing equipment structure or operating parameters. The aim of this paper is to review the most recent progresses in this aspect and to identify the future development in successfully considering turbulence effects on flotation processes. Full article
(This article belongs to the Special Issue Interactions between Bubbles and Solid Particles during the Flotation Process)
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