Experimental and numerical studies of launder configurations in a two-phase flotation system

Brito-Parada, Pablo R.; Cilliers, J.J.

doi:10.1016/j.mineng.2012.03.009

Cited by 18 publications

(5 citation statements)

References 15 publications

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“…While this reduces the effects of feed variability, it does not allow the systematic investigation of particle size effects explicitly. Other laboratory flotation systems that operate continuously have been developed by Brito-Parada and Cilliers (2012) and Shean et al (2017). The former used a 50 L flotation tank with continuous recycle to test different overflowing and launder configurations while, more recently, Shean et al (2017) developed a continuous 70 L laboratory flotation cell with the objective of developing and optimising a flotation control system based on peak air recovery; however these systems were two phase (surfactant solution and air) only.…”

Section: Introductionmentioning

confidence: 99%

The effect of particle size distribution on froth stability in flotation

Norori-McCormac

Brito-Parada

Hadler

et al. 2017

Separation and Purification Technology

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Separation of particles of different surface properties using froth flotation is a widely-used industrial process, particularly in the minerals industry where it is used to concentrate minerals from ore. One of the key challenges in developing models to predict flotation performance is the interdependent nature of the process variables and operating parameters, which limits the application of optimising process control strategies at industrial scale. Froth stability, which can be quantified using air recovery (the fraction of air entering a flotation cell that overflows in the concentrate as unburst bubbles), has been shown to be linked to flotation separation performance, with stable froths yielding improved mineral recoveries. While it is widely acknowledged that there is an optimum particle size range for collection of particles in the pulp phase, the role of particle size on the measured air recovery and the resulting link to changes in flotation performance is less well understood. This is related to the difficulty in separating particle size and liberation effects.In this work, the effects of particle size distribution on air recovery are studied in a single species (silica) system using a continuous steady-state laboratory flotation cell. This allows an investigation into the effects of particle size distribution only on froth stability, using solids content and solids recovery as indicators of flotation performance. It is shown that, as the cell air rate is increased, the air recovery of the silica system passes through a peak, exhibiting the same froth behaviour as measured industrially. The air recovery profiles of systems with three different particle size distributions (d80 of 89.6, 103.5 and 157.1 m) are compared. The results show that, at lower air rates, the intermediate particle size distribution (103.5 m) yields the most stable froth, while at higher air rates, the finest particles (89.6 m) result in higher air recoveries. This is subsequently linked to changes in flotation performance. The results presented here highlight, for the first time, the link between particle size distribution in flotation feeds, air recovery and flotation performance. The results demonstrate that there is an optimal air rate for each particle size distribution, therefore changes in particle size distribution in the feed to flotation cells require a change in air rate in order to maximise mineral recovery.

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Section: Introductionmentioning

confidence: 99%

The effect of particle size distribution on froth stability in flotation

Norori-McCormac

Brito-Parada

Hadler

et al. 2017

Separation and Purification Technology

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“…External launders increase the FTD, which increases the probability of stagnant zones and the chance of lower recovery, as documented by [3,16,69]. Experimental and numerical results obtained by Brito-Parada and Cilliers [63] show that a low liquid overflow rate and a low air recovery rate are associated with launder configurations where stagnant zones occur. External launders require that a bank of cells be spaced widely apart, which increases the overall footprint of the flotation circuit.…”

Section: External Peripheral Laundermentioning

confidence: 86%

“…They exist in the form of a channel into which the froth overflows [14] and is directed to the concentrate weir. A launder can also be defined as an inclined drainage channel that removes the froth from the cell lip [63]. Therefore, launders are found internally at the top of cylindrical flotation cells (Figure 2) or outside the overflow lip.…”

Section: Laundersmentioning

confidence: 99%

“…Their function is to gather and transport the froth out of the flotation cell in both cylindrical and rectangular cells. The design of launders varies with cell size, type of flotation cell, and intended duty [13,63]. Gorain et al [64] states that, with internal launder configurations, particularly radial launders, the launder fingers/spoons extend from the wall of the flotation cell towards the centre of the cell.…”

Section: Laundersmentioning

confidence: 99%

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A Review of Flotation Physical Froth Flow Modifiers

Jera

Bhondayi

2021

Minerals

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Over the past few decades, the need to process more minerals while lowering capital costs has led to an increase in the size of flotation cells, e.g., 0.03 m3 to 1000 m3. However, this increase has created new challenges in the operation and design of industrial flotation cells, particularly in terms of froth removal, because the distance the froth must travel increases with an increase in the flotation cell diameter. This has a negative impact on recovery. Physical froth flow modifiers can be used to improve froth removal. Their major functions are to modify and optimise the flow of the froth, improve froth drainage, reduce dead zones, and improve froth flow and removal dynamics. Therefore, physical froth flow modifiers are discussed, evaluated, and compared in this paper. The literature indicates that physical froth flow modifiers such as crowders and launders are used extensively as industrial solutions to enhance froth transport and recovery in large flotation cells. Other modifiers (including froth baffles and froth scrapers) have been found to have a profound effect on local froth phase sub-processes, including drainage and bubble coalescence. However, industrial uptake is either dwindling or limited to small-volume rectangular/U-shaped cells in the case of scrapers, or, there is no uptake at all in the case of froth baffles. Further research on how some of the physical modifiers (e.g., baffles and launders) impact the selectivity of particles is required.

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“…Although retrofits have been widely incorporated into industrial operations and there are several studies of their effect on flotation performance, − the influence of retrofit designs on turbulence has not yet been explored. This gap in the literature may relate to the technical challenges associated with the measurement of the turbulent fluid dynamics of opaque multiphase systems.…”

Section: Introductionmentioning

confidence: 99%

Effect of Retrofit Design Modifications on the Macroturbulence of a Three-Phase Flotation Tank─Flow Characterization Using Positron Emission Particle Tracking (PEPT)

Cole

Mesa

Heerden

et al. 2023

Ind. Eng. Chem. Res.

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Turbulence in stirred tank flotation tanks impacts the bulk transport of particles and has an important role in particle−bubble collisions. These collisions are necessary for attachment, which is the main physicochemical mechanism enabling the separation of valuable minerals from ore in froth flotation. Modifications to the turbulence profile in a flotation tank, therefore, can result in improvements in flotation performance. This work characterized the effect of two retrofit design modifications, a stator system and a horizontal baffle, on the particle dynamics of a laboratory-scale flotation tank. The flow profiles, residence time distributions, and macroturbulent kinetic energy distributions were derived from positron emission particle tracking (PEPT) measurements of tracer particles representing valuable (hydrophobic) mineral particles in flotation. The results show that the use of both retrofit design modifications together improves recovery by increasing the rise velocity of valuable particles and decreasing turbulent kinetic energy in the quiescent zone and at the pulp−froth interface.

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Experimental and numerical studies of launder configurations in a two-phase flotation system

Cited by 18 publications

References 15 publications

The effect of particle size distribution on froth stability in flotation

The effect of particle size distribution on froth stability in flotation

A Review of Flotation Physical Froth Flow Modifiers

Effect of Retrofit Design Modifications on the Macroturbulence of a Three-Phase Flotation Tank─Flow Characterization Using Positron Emission Particle Tracking (PEPT)

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