Optimum combination of size ratio, density ratio and concentration to minimize free surface segregation

Alonso, M.; Satoh, Munetake; Miyanami, Kei

doi:10.1016/0032-5910(91)80122-y

Cited by 65 publications

(48 citation statements)

References 10 publications

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“…Glass beads with a density of 2,595 kg/m 3 are painted white, and lead shot with a density of 11,370 kg/m 3 are naturally black. As previous work [1,2,27,28] showed that denser (lighter) particles segregate toward the center (periphery) of the bed, we wanted to set the opposite initial condition in order to observe radial segregation over the longest period. This means the initial condition has the low density white particles initially in the center of the granular bed, surrounded by higher density black particles out to the tube boundary.…”

Section: Methodsmentioning

confidence: 99%

“…Even in the general case of dry flows there have been relatively few experiments focusing on density segregation: previous work includes that of Drahun and Bridgwater [19] on avalanching flows down an incline; of Alonso et al [1] who measured size and density segregation in a two-dimensional horizontal rotating cylinder; of Metcalfe and Shattuck [2] who measured segregation rates in a three-dimensional horizontal rotating cylinder in the size ratio-density ratio plane; and of Jain et al [16] who report segregation patterns over a large portion of the size ratio-density ratio plane for a quasi-2-dimensional horizontal rotating cylinder.…”

Section: Introductionmentioning

confidence: 98%

“…Particles tumbled in rotating horizontal or inclined containers, with or without through-flow, can segregate granular material radially and axially due to differences in particle size, shape, and density [1][2][3][4][5][6]. Most work on segregation in partially filled tumblers has considered dry granular flow, where the interstitial fluid is air.…”

Section: Introductionmentioning

confidence: 98%

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Experimental study of density segregation at end walls in a horizontal rotating cylinder saturated with fluid: friction to lubrication transition

et al. 2012

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What is the effect of interstitial fluid viscosity on granular density segregation in a horizontal rotating cylinder? We conducted experiments in the rolling regime with equal amounts of equal sized high and low density, nearly spherical granular particles saturated with air, water, and waterglycerin mixtures. We held particle density, rotation rate and characteristic length scale constant to highlight differences due purely to the interstitial fluid. Images of the granular flow at an end wall were used to determine radial and axial density segregation rates and patterns. Over a four decade change in viscosity, segregation rates varied by only a factor of two. However, for ratios of lubrication to frictional stresses above one, segregation rates decreased by about 30%, and we observed several notable phenomena in the segregation pattern formation. These were a creeping mode of radial density segregation, a change in shape of the granular bed to kidney shaped from flat, and for cylinders more than half full the Electronic supplementary material The online version of this article (typically reported unsheared central portion of the granular bed (often referred to in the literature as a core region) was disrupted by a wavy instability where the rate of disappearance of the core region decreased as the fill level increased.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

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Experimental study of density segregation at end walls in a horizontal rotating cylinder saturated with fluid: friction to lubrication transition

et al. 2012

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“…[51,71] Variations on this broad theme are seen in special circumstances. [77][78][79][80] On a larger time scale, particles may segregate axially, forming alternating transverse bands of the different species. [62,[81][82][83][84][85][86] Considerable recent work has focussed on coarsening of the bands over long times.…”

Section: Example 6: Chaotic Advection In a Rotating Cylinder With Wedgesmentioning

confidence: 99%

Rheology and Mixing of Granular Materials

Khakhar

2011

Macro Materials & Eng

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Polymer processing entails several operations involving the handling of granular materials. We present here a review of some recent advances in the field which are of relevance to polymer processing. The stress distribution in static material is considered with application to particulates in bins and hoppers. A new model for description of the rheology of dense granular flows is reviewed. A model for surface granular flows with application to rotating cylinders is discussed. Finally the mixing and segregation is tumbling mixers is reviewed. magnified image

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“…Previous works suggest that volume fraction of the mixing particles play some role on the final/steady state of mixing achieved [4,9]. Therefore, the size effect is investigated at several α values, keeping at 0.22.…”

Section: Size Effect At a Fixed Density Ratiomentioning

confidence: 99%

Effects of size and density differences on mixing of binary mixtures of particles

Musha

Chandratilleke

Chan

et al. 2013

AIP Conference Proceedings

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Abstract. Mixing of granular materials is an important operation in many industries such as the pharmaceutical industry. Generally, a granular material to be mixed can have particles of different densities and sizes, which makes the mixing difficult. Several studies have addressed the issue of finding the optimum combinations of the size and density ratios of binary particles for mixing to happen, using rotating drums as the mixers. For mixtures of particles uniform in either the size or density, we have shown previously that mixing index of the mixtures can be represented by a unique function of the variable, 3 where β (<1) and γ (<1) are the size and density ratios respectively. This concept was demonstrated for a volume fraction, α = 0.5 of the large (or denser) particles, using a vertically shafted cylindrical mixer. The implication of this result is that the size effects can be represented by an equivalent density difference. Here, this concept is further investigated for mixing of binary particles having different combinations of β and γ, at different values of α. It is shown that the variation of the mixing index can be expressed as a function of the three variables, β, γ and α. Such a relationship will be useful in predicting the outcomes of mixing of binary particles.

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Optimum combination of size ratio, density ratio and concentration to minimize free surface segregation

Cited by 65 publications

References 10 publications

Experimental study of density segregation at end walls in a horizontal rotating cylinder saturated with fluid: friction to lubrication transition

Experimental study of density segregation at end walls in a horizontal rotating cylinder saturated with fluid: friction to lubrication transition

Rheology and Mixing of Granular Materials

Effects of size and density differences on mixing of binary mixtures of particles

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