Mathematical modeling of separation characteristics of a coal-washing spiral

Das, Surya Kanta; Godiwalla, K M; Panda, Lopamudra; Bhattacharya, K K; Singh, Ratnakar; Mehrotra, Shanta

doi:10.1016/j.minpro.2007.05.007

Cited by 41 publications

(14 citation statements)

References 15 publications

(29 reference statements)

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“…Most recently, Stokes et al [6,7] derived a new model for helically-symmetric clearfluid flow in the thin film limit which yields the primary and secondary flows, along with the free surface shape. Das et al [8] considered a particle-laden flow in a spiral separator and applied the particle dispersion model of Bagnold [9], showing that the particles of a larger relative gravity accumulate toward the center of the spiral. In their analysis, however, the viscosity and density of the mixture are constant, independent of the local particle concentration.…”

Section: Introductionmentioning

confidence: 99%

Behavior of a particle-laden flow in a spiral channel

2014

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Spiral gravity separators are devices used in mineral processing to separate particles based on their specific gravity or size. The spiral geometry allows for the simultaneous application of gravitational and centripetal forces on the particles, which leads to segregation of particles. However, this segregation mechanism is not fundamentally understood, and the spiral separator literatures does not tell a cohesive story either experimentally or theoretically. While experimental results vary depending on the specific spiral separator used, present theoretical works neglect the significant coupling between the particle dynamics and the flow field. Using work on gravity-driven monodisperse slurries on an incline that empirically accounts for this coupling, we consider a monodisperse particle slurry of small depth flowing down a rectangular channel that is helically wound around a vertical axis. We use a thin-film approximation to derive an equilibrium profile for the particle concentration and fluid depth and find that, in the steady state limit, the particles concentrate towards the vertical axis of the helix, leaving a region of clear fluid.

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Section: Introductionmentioning

confidence: 99%

Behavior of a particle-laden flow in a spiral channel

2014

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“…Computational simulations were performed by Wang & Andrews (1994), Matthews et al (1998Matthews et al ( , 1999 and Stokes (2001). Das et al (2007) used the semi-empirical model of Holland-Batt (1989) to investigate the behaviour of particles in such a flow, assuming that the particles do not modify the flow, while acknowledging that this model sometimes predicts larger flow depths than reported in experiments.…”

Section: Introductionmentioning

confidence: 99%

Thin-film flow in helically-wound rectangular channels of arbitrary torsion and curvature

2014

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Laminar helically-symmetric gravity-driven thin-film flow down a helically-wound channel of rectangular cross-section is considered. We extend the work of Stokes et al. (2013) and Lee et al. (2014) to channels with arbitrary curvature and torsion or, equivalently, arbitrary curvature and slope. We use a non-orthogonal coordinate system and, remarkably, find an exact steady-state solution. We find that the free-surface shape and flow have a complicated dependence on the curvature, slope and flux down the channel. Moderate to large channel slope has a significant effect on the flow in the region of the channel near the inside wall, particularly when the curvature of the channel is large. This work has application to flow in static spiral particle separators used in mineral processing.

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“…Для усовершенствования пневмосепараторов необходимы теоретические исследования движения частиц на рабочей поверхности сепаратора [2]. В работах [3][4][5] представлены математические модели движения частицы в винтовом сепараторе. В [6] исследованы процессы сепарации в винтовом сепараторе методом дискретных элементов.…”

Section: аннотацияunclassified