Froth stability, particle entrainment and drainage in flotation — A review

Subrahmanyam, T.V.; Forssberg, Eric

doi:10.1016/0301-7516(88)90004-x

Cited by 136 publications

(37 citation statements)

References 21 publications

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“…The entrainment recovery, in all size fractions, is less than the corresponding water recovery, although the recovery of the finer size fraction (i.e., under 25 µm) closely approaches the water recovery value. These results are comparable to those of most of the previous works on this subject, taking into account the water recovery range and the particles size studied [5][6][7][8][9]21]. As expected, the recovery by true flotation is generally greater than the recovery by entrainment, with the exception of the finer fraction of the FeO.…”

Section: Resultssupporting

confidence: 89%

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Influence of Froth Height on Column Flotation of Kaolin Ore

Pita

2017

Minerals

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Abstract:The influence of the froth height in the reverse flotation of kaolinitic ore was analyzed based on the recovery by entrainment and by true flotation of iron, titanium and manganese oxides (FeO, TiO 2 and MnO). Also, the influence of the particle size in the drainage process was analyzed. The recovery by entrainment and by true flotation of the three oxides is inversely proportional to the froth height. The entrained particles are drained more easily in the froth phase than the floated particles since they are not attached to the bubbles. The recovery by entrainment and drainage of the entrained material is similar for the three oxides. However, the recovery by true flotation and drainage of the floated material is different for the three oxides. FeO has the lowest recovery, as a consequence of the minor contribution of its hydrophobic minerals, while MnO has the greatest recovery values. For the entrained material, the finest fraction is entrained more easily, but it is also drained more easily, meaning these particles have more mobility in the froth zone. For the true floated material, the finest fraction is drained more easily, indicating the greater mobility of these particles in the froth; however, the coarsest fraction is drained more easily than the two intermediate fractions, indicating the weaker attachment of the larger particles to the bubbles.

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Section: Resultssupporting

confidence: 89%

“…In fact, for the three coarser fractions the y-intercept of the linear regression decreases slightly with increasing particle size. These results are in agreement with previous studies by Subrahmanyam and Forssberger [6], Kirjavainen [7], Zheng et al [8], and Warren [11], in which they concluded that fine particles are more easily entrained.…”

Section: Oxidesupporting

confidence: 93%

Influence of Froth Height on Column Flotation of Kaolin Ore

Pita

2017

Minerals

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“…In addition, fine particles are easily suspended in the water or the water film surrounding the bubbles in the region below the pulp/froth interface. Hence, fine particles have more chances to travel up through the froth to the concentrate (Subrahmanyam and Forssberg, 1988). Generally, it is believed that mineral particles smaller than 50 µm are readily recovered by entrainment.…”

Section: Effect Of Clay Minerals On Entrainmentmentioning

confidence: 99%

“…In Figure 5.7 the froth stability increased when kaolinite content was increased. Both high froth stability and smaller bubble size are typical characteristics of entrainment (Liu and Peng, 2014;Subrahmanyam and Forssberg, 1988;Wang and Peng, 2013;Wang et al, 2015a). Therefore, the decrease of copper grade with the increase of kaolinite proportion is also likely to be due to mechanical entrainment by which kaolinite minerals suspended in water due to their fine size, move upwards, enter the flotation froth and finally leave with the concentrate.…”

Section: Effect Of Clay Minerals On Froth Performancementioning

confidence: 99%

Mitigating the deleterious effect of clay minerals on copper flotation

Wang¹

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Clay minerals have a deleterious effect on the mineral flotation process. Generally, two major phenomena are observed in industry when processing high clay ores: no froth formed on the top of the pulp phase and few valuable minerals loaded on the top of froth. This is an ARC Linkage project with support from Pionera, a reagent company manufacturing biopolymers.The objective of the project is to define the different effects of clay minerals on copper flotation, and then to mitigate the deleterious effects of specific clay minerals in copper flotation by biopolymers and other means.In this research, two types of clay minerals, swelling bentonite with a 2:1 structure and nonswelling kaolinite Q38 with a 1:1 structure, were chosen to represent two typical kinds of clay minerals often seen in industrial flotation plants. The influence of bentonite and kaolinite on copper flotation was investigated. It was found that bentonite and kaolinite affected the copper flotation in a different way. Increasing the proportion of bentonite increased the pulp viscosity that reduced the amount of froth on the top of slurry and decreased flotation rate, resulting in a lower copper recovery. On the other hand, increasing the kaolinite content mainly decreased the copper grade by entrainment that is characterised by smaller bubble size and higher froth stability. The different roles of bentonite and kaolinite in the flotation were associated with their unique structure properties. Also, the collector and frother dosage plays an important role in specifying the different effect of bentonite and kaolinite on copper flotation performance.To mitigate the deleterious effect of kaolinite, three lignosulfonate biopolymers from Pionera, DP-1775, DP-1777 and DP-1778 with different structures, were examined. While rheological measurements indicated that these biopolymers dispersed the kaolinite aggregates, a beneficial effect of biopolymers on copper flotation in the presence of kaolinite was not observed. Instead, interactions of biopolymers with the frother appeared to enhance the froth stability and therefore further reduced copper grade by mechanical entrainment. Two-phase foam characterization revealed that the foam height increased in the blends of biopolymers with the frother. The dispersing and foaming abilities of biopolymers were governed by their structure features such as the content of functional groups, the molecular weight and counterions.The three biopolymers, DP-1775, DP-1777 and DP-1778, were also tested to reduce the negative effect of bentonite in copper flotation. Rheological measurements indicated that all of II the three biopolymers could not significantly reduce the pulp viscosity which was dictated by bentonite. This is consistent with the observation that none of the three biopolymers could enhance the copper recovery effectively. Electrolytes were then used to mitigate the deleterious effect of bentonite on copper flotation through reducing the high pulp viscosity.

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“…As the final separation phase in a flotation cell, the froth phase is a crucial determinant of the grade and recovery of the flotation process (Wills and Napier-Munn, 2006). The importance of the cleaning and recovering actions of the froth in flotation has been well recognised (Schuhmann, 1942, Moys, 1978, Feteris et al, 1987, Subrahmanyam and Forssberg, 1988, Yianatos et al, 1988.…”

Section: Function Of the Frothmentioning

confidence: 99%

An investigation of flotation froth rheology

Li¹

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Flotation froth is of significant importance because it ultimately determines overall flotation performance. Froth recovery, the fraction of valuable minerals coming into the froth phase which survive and report to the concentrate, has been widely used to evaluate the efficiency of transporting the valuable minerals from the pulp-froth interface to the concentrate launder.Froth recovery is related to the time that particles spend in the froth and the rate at which bubbles burst.It is believed that froth rheology has an impact on froth recovery in flotation. A more viscous froth should resist motion towards the lip, rising vertically before overflowing into the cell launder, resulting in significantly higher froth residence times and increased probability of froth drop back as well as froth collapse. Very little work has been done to study the rheology of a highly mineralised flotation froth and how it impacts on froth recovery. Therefore, this project aims to gain an insight into the correlations between froth properties, froth rheology and flotation performance.To achieve this goal, a novel method to measure froth rheology properly was developed in this project. The method involves the use of a rotating vane surrounded by a tube. The tube is required to minimise the adverse effects of the horizontal flow on the measurement.Equations have been provided to convert the vane rotational speed and measured torque to shear rate and shear stress, depending on whether the froth within the tube is fully or partially sheared.In order to investigate the correlation between froth rheology and froth properties, flotation tests were performed in a 20 L continuous flotation cell using a synthetic ore which was a mixture of chalcopyrite and silica. The flotation tests, conducted under different flotation conditions (i.e. air rate, froth depth, impeller speed, feed grade and feed P80), resulted in significant changes in the froth properties and the viscosity of the froth. The froth was shown to be shear thinning with minor yield stress. It could be modelled using a power-law model with the consistency index of this function being able to be used to represent the degree of viscosity of the froth phase.The observed change in the froth viscosity was shown to be largely a function of the change in the bubble size and the percentage of the bubble surface covered by particles. Smaller bubbles and a greater coverage of particles on the bubble surface result in a greater resistance to froth motion. Thus changes in cell operation which reduce the froth bubble size (e.g. higher impeller speeds, higher frother dosage rates) will result in a more viscous froth. Higher feed grades and a smaller particle size which result in a greater proportion of bubble surface coverage will also result in higher froth viscosities.A model was proposed which relates the apparent viscosity of the froth to the shear rate, the froth bubble size, the gas volume fraction in the froth, the percentage of the bubble surface covered by particles and a fittabl...

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Froth stability, particle entrainment and drainage in flotation — A review

Cited by 136 publications

References 21 publications

Influence of Froth Height on Column Flotation of Kaolin Ore

Influence of Froth Height on Column Flotation of Kaolin Ore

Mitigating the deleterious effect of clay minerals on copper flotation

An investigation of flotation froth rheology

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