Particle entrainment model for industrial flotation cells

Yianatos, J.; Contreras, F.

doi:10.1016/j.powtec.2009.10.001

Cited by 71 publications

(21 citation statements)

References 23 publications

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“…However, the intensity of both phenomena can be different [21,37,38]. Factors influencing the recovery of hydrophilic material includes (i) solid concentration in the suspension, (ii) retention time, (iii) froth structure, and (iv) particle size [39]. Important influencing parameters will be explained in detail to understand their importance on the froth fractionation performance:…”

Section: Particle Entrainment In Flotation Frothmentioning

confidence: 99%

Separation of cellulose fibres from pulp suspension by froth flotation fractionation

Redlinger-Pohn

Grabner

Zauner

et al. 2016

Separation and Purification Technology

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Flotation of cellulose pulp suspension in paper industry is primarily used for separation of ink particles from cellulose fibres. Entrainment, an unwanted phenomena well described in the field of mineral flotation, also leads to a removal of fibres with the flotation froth. We find that the entrainment phenomena can be used for the separation of long fibres from a fibre pulp suspension, and hence for pulp fractionation. Specifically, we use a 2D bubble column to investigate the influence of (i) bubble size, (ii) wash rate and (iii) stirring on the separation of long fibres from cellulose pulp suspension. Separation of fibres from fibre pulp suspension is tested for mechanical pulp and chemical pulp. We find that size selective recovery yields best result for (i) large bubbles, and (ii) additional washing due to the increase of small particle drainage. However, both strategies lead to a reduction of the total recovery rate. Stirring significantly improved the total recovery and benefited the selective separation. Best results are achieved with small bubbles for chemical pulp. For mechanical pulp, fractionation is more challenging due to lower froth stability, but still fibres with a reduced amount of smaller fraction can be recovered.

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Section: Particle Entrainment In Flotation Frothmentioning

confidence: 99%

Separation of cellulose fibres from pulp suspension by froth flotation fractionation

Redlinger-Pohn

Grabner

Zauner

et al. 2016

Separation and Purification Technology

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“…Bubble size distribution, number of bubbles, froth velocity and stability were the main visual features extracted from the froth images. A simple empirical dimensionless model was presented to calculate the mineral gangue recovered per size class by entrainment, in terms of the water recovery in an industrial flotation cell [33].…”

Section: Trends In Green Chemistrymentioning

confidence: 99%

Research Activities Related to Flotation Process

Ka¹

2015

Trends in Green chem

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Flotation initially originated from the field of mineral processing. The importance of this process to the economy of the whole industrial world is considered to be enormous. Since for many years various particulate solids besides minerals have been extracted by using this effective gravity separation method with many interesting applications in the treatment of wastewater, looking for sustainability. Certain significant activities in flotation research were reviewed in the present, with main focus in the contribution of physical chemistry to flotation; i.e. zeta-potential measurements, contact angle etc., including examining the role of bubble and particle size played with regard to the process. Alternative bubble generation methods were examined, such as electro flotation and dissolved-air flotation-the latter technique is mainly intended for water treatment applications.Keywords: Hydrophobicity, Dissolved-air flotation, Electroflotation, Biosorption, Waste water IntroductionLet us start this chapter by saying that flotation is really an old process: the historian Herodotus in ancient Greece is probably the first person that described a process similar to flotation, in the 5 th century B.C., for the separation of gold particles from sand using fatty substances. And later, in the 15 th century A.D., the Arabs used resins for the selective separation of azurite (a copper mineral) from gangue. These are considered to be the main historical roots of flotation, which is based on the idea of applying rising gas bubbles as the transport medium [1]. The attachment of bubbles to particles transfers the solids from the body of water to the surface.Hydrophobicity refers to the property of a molecule, cluster, micro-organism or mineral surface that is repelled from a mass of water. Further, it was noted that the term hydrophobicity (a Greek word) has been differently understood in various fields [2]. Floatability and hydrophobicity, however, are inter-related, focusing often on the application of collectorless flotation. Attention may be paid to a series of relevant reviews on the area [3][4][5][6]. Below a brief survey is given on selected recent papers for different applications of flotation, from a really vast literatureshowing well (as we believe) that chemistry contributes in various ways in flotation research. Coal beneficiation is one of the most effective methods for removing minerals, such as gangues and pyrite, and pollutants such as sulfur, before the burning of coal.In general, the beneficiation process of low rank coals (about the 50% of the world's total coal deposits) is more difficult to achieve than that of bituminous and/or anthracite coals. Lignite is the most important mineral commodities for Greece, according to Anastassakis [7]; its reserves approach to about 4000 Mt. It was pointed out that in the future effective reagents should be invented for effective flotation process (being a physico-chemical one) [8]. A better understanding of the surface chemistry of sulfidewater interfaces was tried...

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“…An increase in gangue recovery will cause a decrease in concentrate grade and thus it is expected that there will be an inverse relationship between the water recovered to concentrate and concentrate grade. This is demonstrated by Yianatos and Contreras (2010) who investigated the effect of water recovery on the concentrate grade in an industrial 130 m3 flotation cell treating a copper ore (Figure 2-7). They showed that an increase in the water recovery led to a significant decrease in the concentrate copper grade, highlighting the importance of water recovery in determining the gangue recovery and concentrate grade.…”

Section: Water Recoverymentioning

confidence: 94%

“…To date, a number of models have been proposed to estimate and predict entrainment with the objective of better controlling or predicting flotation performance (Bisshop an White, 1976;Moys, 1978;Ross and Van Deventer, 1988;Kirjavainen, 1992;Maachar and Dobby, 1992;Savassi et al, 1998;Neethling and Cillers, 2002a;Neethling and Cillers, 2009;Yianatos and Contreras, 2010). …”

Section: Problem Statementmentioning

confidence: 99%

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Entrainment of fine particles in froth flotation

Wang¹

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Entrainment has become a significant issue nowadays with fine grinding being used to liberate valuable minerals from low grade and complex ores to increase "true flotation". Entrainment results in large amounts of fine gangue materials reporting to flotation concentrates along with recovered valuable minerals and reduces the final product quality. In froth flotation, entrainment is the dominant recovery mechanism for fine gangue mineral particles, and it is influenced by a number of factors in both the pulp and froth phase, including particle properties (e.g. particle size and density) and flotation operational variables (e.g. gas flowrate, froth depth, impeller speed and reagent dosage).A number of models incorporating different factors have been developed to estimate entrainment recovery. Most of these models relate entrainment recovery to two parameters: the water recovery to concentrate, and the degree of entrainment, a classification factor to account for the degree of drainage of entrained particles with respect to the water in the pulp and froth phases of a flotation cell. However, there are still significant barriers to be overcome before they can be applied for routine estimation of entrainment in industrial applications. There is no consensus as to the variables which significantly affect the entrainment process and should therefore be included in the model as well as to the mechanisms involved.This thesis investigated the effect of flotation operational factors and particle properties on the entrainment parameters (i.e. degree of entrainment and water recovery) and the mechanisms underpinning the observed effects. The objective of the thesis was to develop a comprehensive understanding of the key operating conditions and particle attributes influencing the entrainment of gangue minerals in flotation, which should enable the development of a more sophisticated predictive entrainment model by more accurately predicting the degree of entrainment and water recovery.A two level factorial experimental program was adopted to investigate the effect of impeller speed, gas flowrate, froth height and specific gravity of gangue minerals on the degree of entrainment.Batch flotation experiments were performed in a 3.5 L conventional Agitair flotation cell using a feed which was a mixture of liberated chalcopyrite and one of two liberated gangue minerals, quartz and hematite. Results show that there was no direct correlation between the degree of entrainment and water recovery, indicating that the key drivers of water recovery were not the same as those that affected the degree of entrainment.ii The degree of entrainment was significantly influenced by particle size, particle density, frother and the interaction between gas flowrate and froth height. The mechanisms underpinning the effect of these significant influencing factors were investigated. Results suggest that the classification of gangue mineral particles mainly occurs at the pulp/froth interface region. Whether a particle moves upward into the frot...

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Particle entrainment model for industrial flotation cells

Cited by 71 publications

References 23 publications

Separation of cellulose fibres from pulp suspension by froth flotation fractionation

Separation of cellulose fibres from pulp suspension by froth flotation fractionation

Research Activities Related to Flotation Process

Entrainment of fine particles in froth flotation

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