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J A Finch - One of the best experts on this subject based on the ideXlab platform.
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using sound to study the effect of Frothers on the breakaway of air bubbles at an underwater capillary
Langmuir, 2017Co-Authors: Pengbo Chu, Randolph Pax, Ray Langlois, J A FinchAbstract:Frothers, a class of surfactants, are widely employed in froth flotation to aid the generation of small bubbles. Their action is commonly explained by their ability to hinder coalescence. There are occasional references suggesting that the frother may also play a role in the initial breakup of the injected air mass. This work investigates the possible effect of the frother on breakup by monitoring air bubbles produced quasi-statically at an underwater capillary. Under this condition, breakup is isolated from coalescence and an impact of Frothers on the detached bubble can be ascribed to an impact on breakup. The breakaway process was monitored by an acoustic technique along with high-speed cinematography. The results showed that the presence of Frothers did influence the breakaway process and that the acoustic technique was able to detect the impact. It was demonstrated that the acoustic frequency and acoustic damping ratio depend upon the frother type and concentration and that they are associated with a...
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frother structure property relationship effect of alkyl chain length in alcohols and polyglycol ethers on bubble rise velocity
Minerals Engineering, 2016Co-Authors: Yue Hua Tan, J A FinchAbstract:Abstract In mineral flotation, Frothers are used to produce fine bubbles, reduce bubble rise velocity, and stabilize the froth, three properties that enhance the flotation process. These properties depend on the frother structure and this paper is part of an investigation into the frother structure-property relationship. The property here is bubble rise velocity and the structural variation is alkyl chain length of two frother families, alcohols and polyglycols. Single bubble rise velocity profiles were determined in a 350 cm column. Velocity at 300 cm as a function of concentration is determined and as a measure of the impact of structure on reduction in bubble rise velocity the concentration at minimum velocity (CMV) is estimated. The effect of increasing alkyl chain length is to decrease CMV by about ca. 90% in alcohols and ca. 70% in polyglycols for every one carbon addition. Taking log CMV as a function of the number of carbons in the alkyl chain gives a series of self-similar linear plots. An argument relating bubble rise velocity to surfactant molecule packing on the bubble surface is proposed.
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a novel approach to prevent bubble coalescence during measurement of bubble size in flotation
Journal of Central South University, 2014Co-Authors: Wei Zhang, Jan E Nesset, J A FinchAbstract:Effect of Frothers in preventing bubble coalescence during flotation of minerals has long been investigated. To evaluate the performance of a frother, an apparatus to measure the bubble size is a basic necessity. McGill Bubble Size Analyzer (MBSA) or bubble viewer that has been developed and completed by McGill University’s Mineral Processing Group during the last decade is a unique instrument to serve this purpose. Two parameters which are thought to influence the bubble size measurements by McGill bubble viewer include water quality and frother concentration in the chamber. Results show that there is no difference in Sauter mean (D32) when tap or de-ionized water was used instead of process water. However, the frother concentration, in this research DowFroth 250 (DF250), inside the chamber exhibited a pronounced effect on bubble size. Frother concentration below a certain point can not prevent coalescence inside the chamber and therefore caution must be taken in plant applications. It was also noted that the frother concentration which has been so far practiced in plant measurements (CCC75-CCC95) is high enough to prevent coalescence with the bubble viewer.
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bubble size gas holdup and bubble velocity profile of some alcohols and commercial Frothers
International Journal of Mineral Processing, 2013Co-Authors: Abdollah Rafiei, A M Elmahdy, J A FinchAbstract:Abstract Frothers are used in flotation to reduce bubble size and as a consequence increase gas holdup. For 1-alcohols, C 4 to C 7, and three commercial Frothers, MIBC, DF250 and F150, it is shown that at equivalent Sauter mean bubble size gas holdup depends on frother type. The paper explains the gas holdup result by showing the effect of frother type on single bubble rise velocity profile, i.e., local velocity vs. distance (up to 350 cm). For example, a 1.45 mm bubble in 0.4 mmol/L pentanol hardly slows relative to water only while in 0.4 mmol/L hexanol it reaches minimum velocity. This corresponds to the higher gas holdup in 1-hexanol compared to 1-pentanol. To compare Frothers we introduce velocity at 300 cm vs. concentration and the concentration to reach minimum velocity, CMV. The CMV illustrates the strong frother effect: for example, CMV for the alcohols decreases by about one order of magnitude for every 1 C increase in chain length. The decrease in CMV with frother type correlates with the increase in gas holdup. It is shown that all Frothers tested follow the same minimum velocity-size trend modeled reasonably by the relationship proposed by Karamanev for terminal velocity.
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characterizing Frothers through critical coalescence concentration ccc 95 hydrophile lipophile balance hlb relationship
Minerals, 2012Co-Authors: Wei Zhang, Jan E Nesset, J A FinchAbstract:Frothers are surfactants commonly used to reduce bubble size in mineral flotation. This paper describes a methodology to characterize Frothers by relating impact on bubble size reduction represented by CCC (critical coalescence concentration) to frother structure represented by HLB (hydrophile-lipophile balance). Thirty-six surfactants were tested from three frother families: Aliphatic Alcohols, Polypropylene Glycol Alkyl Ethers and Polypropylene Glycols, covering a range in alkyl groups (represented by n, the number of carbon atoms) and number of Propylene Oxide groups (represented by m). The Sauter mean size (D32) was derived from bubble size distribution measured in a 0.8 m3 mechanical flotation cell. The D32 vs. concentration data were fitted to a 3-parameter model to determine CCC95, the concentration giving 95% reduction in bubble size compared to water only. It was shown that each family exhibits a unique CCC95-HLB relationship dependent on n and m. Empirical models were developed to predict CCC95 either from HLB or directly from n and m. Commercial Frothers of known family were shown to fit the relationships. Use of the model to predict D32 is illustrated.
Jan Drzymala - One of the best experts on this subject based on the ideXlab platform.
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Classification of Flotation Frothers
Minerals, 2018Co-Authors: Jan Drzymala, Przemyslaw B. KowalczukAbstract:In this paper, a scheme of flotation Frothers classification is presented. The scheme first indicates the physical system in which a frother is present and four of them i.e., pure state, aqueous solution, aqueous solution/gas system and aqueous solution/gas/solid system are distinguished. As a result, there are numerous classifications of flotation Frothers. The classifications can be organized into a scheme described in detail in this paper. The frother can be present in one of four physical systems, that is pure state, aqueous solution, aqueous solution/gas and aqueous solution/gas/solid system. It results from the paper that a meaningful classification of Frothers relies on choosing the physical system and next feature, trend, parameter or parameters according to which the classification is performed. The proposed classification can play a useful role in characterizing and evaluation of flotation Frothers.
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Concentration at the Minimum Bubble Velocity (CMV) for Various Types of Flotation Frothers
Minerals, 2017Co-Authors: Przemyslaw B. Kowalczuk, Jan Zawala, Jan DrzymalaAbstract:This paper presents the determination of a concentration at the minimum bubble velocity (CMV) for different types of Frothers, such as straight and branched alkyl chain aliphatic alcohols, 1,ω-diols, poly(propylene glycol) and poly(ethylene glycol) alkyl ethers, n-alkyltrimethylammonium bromides, commercial Frothers and others. The values of terminal rise bubble velocity were reviewed from the experimental data published in the literature for two different types of columns, i.e., a short PAS (used in Polish Academy of Sciences) of height (35 cm) and a long McGill of height (350 cm). The obtained empirical equation is universal and allows one to rapidly and accurately determine the CMV for all surfactants. The proposed empirical model can also be used to predict the terminal bubble velocity–frother concentration curve by knowing the maximum and minimum terminal velocities, as well as the values of CMV. Assessment and usefulness of frother characterization parameters (i.e., concentration at the minimum bubble velocity (CMV), dynamic frothability index (DFI) and critical coalescence concentration (CCC)) were shown in the flotation of coal.
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evaluation of Frothers based on properties of the solids liquid gas system
E3S Web of Conferences, 2017Co-Authors: Jan DrzymalaAbstract:A methodology of selection of Frothers for flotation process is presented in the paper. It is based on performing a series of fractionating flotation tests of a considered material at different doses of a selected frother and calculation of the mass balance of the process. Next, three steps are performed. The first one is determination of the frother dose and kinetic constant or specific rate, using the flotation limits plot relating maximum recovery and process rate, both at a selected maximum recovery of the considered material component. The second step is finding selectivity of separation by using the upgrading Fuerstenau plot, while the third element is Frothers comparison plot in the form of selectivity versus process kinetics, at a selected maximum recovery, and also versus frother dose, for choosing the most suitable frother.
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flotation of copper bearing carbonaceous shale in the presence of amine type Frothers
Annales Universitatis Mariae Curie-Sklodowska sectio AA – Chemia, 2016Co-Authors: Michal Stodulski, Jan DrzymalaAbstract:Hexylamine, chloro-derivative of propylamine, and ammonium chloride were used for flotation of Permian carbonaceous copper bearing shale from the Legnica-Glogow Copper Basin region in SW Poland. It was confirmed that naturally hydrophobic shale, known as Kupferschiefer, can be made floatable by application of short chain amines as Frothers. It was also established that the short chain amine chloro-derivatives as well as salmiac, the first member of the amine family, can be used as a frother for flotation of the investigated shale sample. It results from the paper that the investigated amine Frothers work similarly if the comparison of the flotation results is made using their concentration expressed in relative form taking into account the critical coalescence concentration of the frother.
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three phase contact formation and flotation of highly hydrophobic polytetrafluoroethylene in the presence of increased dose of Frothers
Industrial & Engineering Chemistry Research, 2016Co-Authors: Przemyslaw B. Kowalczuk, Jan Zawala, Jan Drzymala, Dominik Kosior, K MalysaAbstract:The time of a single bubble attachment to a rough hydrophobic solid surface with contact angle greater than 90° in aqueous solutions at different Frothers (n-octanol, α-terpineol and N-octyl-trimethylammonium bromide) in the concentration ranges of 10–6 to 10–3 M was compared with flotation performed under corresponding conditions. A relationship between the time of three-phase contact (TPC) formation at the bubble/liquid/solid interface and flotation rate was obtained. It was found that above a certain frother dose, irrespective of frother type, one could observe significantly longer bubble–solid surface attachment time, which increases from about 2 ms to above 50–60 ms for higher frother concentrations. Accordingly, the flotation rate for the corresponding Frothers concentrations decreased from ca. 0.8 s–1 to values below 0.01 s–1. The obtained results confirm that air can be entrapped at rough highly hydrophobic solid surfaces and show the importance of the bubble attachment time for the flotation kine...
Przemyslaw B. Kowalczuk - One of the best experts on this subject based on the ideXlab platform.
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Classification of Flotation Frothers
Minerals, 2018Co-Authors: Jan Drzymala, Przemyslaw B. KowalczukAbstract:In this paper, a scheme of flotation Frothers classification is presented. The scheme first indicates the physical system in which a frother is present and four of them i.e., pure state, aqueous solution, aqueous solution/gas system and aqueous solution/gas/solid system are distinguished. As a result, there are numerous classifications of flotation Frothers. The classifications can be organized into a scheme described in detail in this paper. The frother can be present in one of four physical systems, that is pure state, aqueous solution, aqueous solution/gas and aqueous solution/gas/solid system. It results from the paper that a meaningful classification of Frothers relies on choosing the physical system and next feature, trend, parameter or parameters according to which the classification is performed. The proposed classification can play a useful role in characterizing and evaluation of flotation Frothers.
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Concentration at the Minimum Bubble Velocity (CMV) for Various Types of Flotation Frothers
Minerals, 2017Co-Authors: Przemyslaw B. Kowalczuk, Jan Zawala, Jan DrzymalaAbstract:This paper presents the determination of a concentration at the minimum bubble velocity (CMV) for different types of Frothers, such as straight and branched alkyl chain aliphatic alcohols, 1,ω-diols, poly(propylene glycol) and poly(ethylene glycol) alkyl ethers, n-alkyltrimethylammonium bromides, commercial Frothers and others. The values of terminal rise bubble velocity were reviewed from the experimental data published in the literature for two different types of columns, i.e., a short PAS (used in Polish Academy of Sciences) of height (35 cm) and a long McGill of height (350 cm). The obtained empirical equation is universal and allows one to rapidly and accurately determine the CMV for all surfactants. The proposed empirical model can also be used to predict the terminal bubble velocity–frother concentration curve by knowing the maximum and minimum terminal velocities, as well as the values of CMV. Assessment and usefulness of frother characterization parameters (i.e., concentration at the minimum bubble velocity (CMV), dynamic frothability index (DFI) and critical coalescence concentration (CCC)) were shown in the flotation of coal.
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three phase contact formation and flotation of highly hydrophobic polytetrafluoroethylene in the presence of increased dose of Frothers
Industrial & Engineering Chemistry Research, 2016Co-Authors: Przemyslaw B. Kowalczuk, Jan Zawala, Jan Drzymala, Dominik Kosior, K MalysaAbstract:The time of a single bubble attachment to a rough hydrophobic solid surface with contact angle greater than 90° in aqueous solutions at different Frothers (n-octanol, α-terpineol and N-octyl-trimethylammonium bromide) in the concentration ranges of 10–6 to 10–3 M was compared with flotation performed under corresponding conditions. A relationship between the time of three-phase contact (TPC) formation at the bubble/liquid/solid interface and flotation rate was obtained. It was found that above a certain frother dose, irrespective of frother type, one could observe significantly longer bubble–solid surface attachment time, which increases from about 2 ms to above 50–60 ms for higher frother concentrations. Accordingly, the flotation rate for the corresponding Frothers concentrations decreased from ca. 0.8 s–1 to values below 0.01 s–1. The obtained results confirm that air can be entrapped at rough highly hydrophobic solid surfaces and show the importance of the bubble attachment time for the flotation kine...
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determination of critical coalescence concentration and bubble size for surfactants used as flotation Frothers
Industrial & Engineering Chemistry Research, 2013Co-Authors: Przemyslaw B. KowalczukAbstract:The paper presents a correlation between the critical coalescence concentration and hydrophilic–lipophilic balance/molecular weight ratio for surfactants used as flotation Frothers. The correlation is based on experimental data published in literature. The obtained empirical equation allows one to accurately predict the critical coalescence concentration based only on the chemical structure of the frother. It was found that another empirical equation, based on one adjustable parameter called the frother concentration constant, can be used to predict the Sauter mean bubble size d32 for different flotation Frothers.
Yuhua Duan - One of the best experts on this subject based on the ideXlab platform.
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effects of Frothers and oil at saltwater air interfaces for oil separation molecular dynamics simulations and experimental measurements
Journal of Physical Chemistry B, 2017Co-Authors: Leebyn Chong, Yungchieh Lai, Mcmahan L Gray, Yee Soong, Fan Shi, Yuhua DuanAbstract:Separating oil from saltwater is a process relevant to some industries and may be aided by bubble and froth generation. Simulating saltwater–air interfaces adsorbed with surfactants and oil molecules can assist in understanding froth stability to improve separation. Combining with surface tension experimental measurements, in this work we employ molecular dynamics with a united-atom force field to linear alkane oil and three surfactant Frothers, methyl isobutyl carbinol (MIBC), terpineol, and ethyl glycol butyl ether (EGBE), to investigate their synergistic behaviors for oil separation. The interfacial phenomena were measured for a range of frother surface coverages on saltwater. Density profiles of the hydrophilic and hydrophobic portions of the Frothers show an expected orientation of alcohol groups adsorbing to the polar water. A decrease in surface tension with increasing surface coverage of MIBC and terpineol was observed and reflected in experiments where the frother concentration increased. Relatio...
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Molecular Dynamics Study of the Bulk and Interface Properties of Frother and Oil with Saltwater and Air
2017Co-Authors: Leebyn Chong, Yungchieh Lai, Yee Soong, Fan Shi, Mcmahan Gray, Yuhua DuanAbstract:For water treatment purposes, the separation processes involving surfactants and crude oil at seawater–air interfaces are of importance for the chemical and energy industries. Little progress has been made in understanding the nanoscale phenomena of surfactants on oily saltwater–air interfaces. This work focuses on using molecular dynamics with a united-atom force field to simulate the interface of linear alkane oil, saltwater, and air with three surfactant Frothers: methyl isobutyl carbinol (MIBC), terpineol, and ethyl glycol butyl ether. For each frother, although the calculated diffusivities and viscosities are lower than the expected experimental values, our results show that diffusivity trends between each frother agree with experiments but the method cannot be applied for viscosity. Binary combinations of liquid (frother or saltwater)–air and liquid–liquid interfaces are equilibrated to study the density profiles and interfacial tensions. The calculated surface tensions of the frother–air interfaces are like that of oil–air, but lower than that of saltwater–air. Only the MIBC–air and terpineol–air interfaces agreed with our experimental measurements. For the frother–saltwater interfaces, the calculated results showed that terpineol has interfacial tensions higher than those of MIBC–saltwater. The simulated results indicate that the frother–oil systems underwent mixing such that the density profiles depicted large interfacial thicknesses
J-p. Franzidis - One of the best experts on this subject based on the ideXlab platform.
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Interpretation of the effect of frother type and concentration on flotation performance in an OK3 cell
Mining Metallurgy & Exploration, 2007Co-Authors: B. A. Comley, M. A. Vera, J-p. FranzidisAbstract:Over the past few decades a great deal of effort has gone into characterizing the effects of frother type and concentration in flotation using a variety of two-phase techniques. Whilst useful and informative, this research still does not assist in the selection of suitable Frothers for three-phase industrial-scale froths. This paper investigates the effects of frother type and concentration in a three-phase industrial froth. The objective was to determine if progress could be made in terms of understanding the behavior of Frothers in flotation and understanding how they affect the sub-processes occurring in the pulp and froth phases and, ultimately, the metallurgical performance of a flotation cell.
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Effect of frother type and concentration on the water recovery and entrainment recovery relationship
Mining Metallurgy & Exploration, 2001Co-Authors: K. Rahal, E. Manlapig, J-p. FranzidisAbstract:A study was undertaken to determine the effects of five industrial Frothers on the relationship between entrainment recovery and water recovery. The experiments were conducted using a Batequip rectangular 60-L steel flotation cell that was run in parallel with the first cell in a copper/silver prefloat rougher circuit. The concentration of the Frothers ranged from 2.5 to 8.4 g/t. The experiments were repeated at three different froth depths. A power function was found to fit this relationship with no discontinuity in the relationship caused by the changes in frother type and concentration and froth depth.
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an evaluation of a direct method of bubble size distribution measurement in a laboratory batch flotation cell
Minerals Engineering, 1994Co-Authors: J P Tucker, J-p. Franzidis, D A Deglon, M C Harris, C T OconnorAbstract:Abstract In this paper a novel bubble sampler is described which allows the measurement of bubble size distributions in flotation cells containing slurries of high solids concentration. The device separates bubbles fromo a slurry into a water solution where they may be measured using a bubble size analyser. An experimental programme of measuring bubble sizes in two and three-phases is reported in which the bubble sampler was evaluated and the effect of different Frothers on the bubble size distribution in two and three-phases was investigated. In two-phase operation (liquid/gas), the bubble sampler was proved to supply accurate and reproducible measurements when compared with measurements made by the bubble size analyser without the sampler fitted. The frother type was found to have the greatest influence on bubble size. With the addition of solids (gold plant tailings) to form a three phase (solid/liquid/gas) system, the mean bubble size was found to increase, and only the further addition of frother could reduce it to its former value. Different Frothers were found to have very different effects on the size of bubbles produced in slurries compared with those produced in two-phase systems. Of the Frothers tested MIBC was found to be the best all around performer in terms of bubble size reduction with increasing solids concentration.
