A Century of Research in Sedimentation and Thickening

Concha, F.; Bürger, Raimund

doi:10.14356/kona.2002009

Cited by 56 publications

(37 citation statements)

References 98 publications

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“…16 However, for monodisperse suspensions, in which the maximum volume fraction is not one, Richardson-Zaki power-law expressions can become inaccurate by allowing unphysical volume fractions. 17 Alternatively, particle hindrance can be taken into account by using a relationship based on a suspension viscosity model. 18 Using a suspension viscosity model has the advantage of reducing the sedimentation velocity to zero at the maximum volume fraction.…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

et al. 2018

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Understanding the sedimentation behaviour of colloidal suspensions is crucial in determining their stability. Since sedimentation rates are often very slow, centrifugation is used to expedite sedimentation experiments. The effect of centrifugal acceleration on sedimentation behaviour is not fully understood. Furthermore, in sedimentation models, interparticle interactions are usually omitted by using the hard-sphere assumption. This work proposes a one-dimensional model for sedimentation using an effective maximum volume fraction, with an extension for sedimentation under centrifugal force. A numerical implementation of the model using an adaptive finite difference solver is described. Experiments with silica suspensions are carried out using an analytical centrifuge. The model is shown to be a good fit with experimental data for 480 nm spherical silica, with the effects of centrifugation at 705 rpm studied. A conversion of data to Earth gravity conditions is proposed, which is shown to recover Earth gravity sedimentation rates well. This work suggests that the effective maximum volume fraction accurately captures interparticle interactions and provides insights into the effect of centrifugation on sedimentation.

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Section: Introductionmentioning

confidence: 99%

Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

et al. 2018

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“…[41][42][43] provide answers. For reviews of the development of that particular branch of fluid mechanics, the reader is referred to [44,45].…”

Section: Introductionmentioning

confidence: 99%

On basic equations and kinematic-wave theory of separation processes in suspensions with gravity, centrifugal and Coriolis forces

Schneider

2017

Acta Mech

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Neglecting inertial and viscosity effects in the bulk flow is a common assumption in the analysis of separation processes in suspensions under the action of gravity or centrifugal and Coriolis forces. While there is a number of examples of particular solutions, the general form of the basic equations for three space dimensions, together with the appropriate boundary and initial conditions, is still uncertain and, with regard to certain aspects, even controversial. An essential point is a proper choice of the variables. Here it is proposed to introduce the mass density of the mixture, the mean mass velocity of the mixture and the total volume flux as a set of dependent variables. After some manipulations, a complete set of basic equations is obtained. It consists of two continuity equations, a generalized drift-flux relation, and two linearly independent components of a vector equation describing the total body force as irrotational. Then, by eliminating the mean mass velocity of the mixture from the set of unknowns, a generalized kinematic-wave equation is derived. It describes kinematic waves that are embedded in a bulk flow that may be one-, two-or three-dimensional. Concerning boundary conditions at solid walls, one has to ascertain whether the total body force at the wall points into the suspension or out of it. In the former case, a thin boundary layer of clear liquid is formed at the wall, whereas in the latter case a thin sediment layer may either stick at the wall or slide along it. Each of those three possibilities leads to a particular boundary condition for the bulk flow in terms of the dependent variables. In addition, initial conditions and kinematic shock relations are briefly discussed. Finally, the application of the kinematic-wave theory to the settling process in rotating tubes is outlined.

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“…A more detailed review on cohesive particles is beyond the scope of this manuscript, however, for further readings on the subject the authors recommend the following works found in the literature (Concha & Bürger, 2002;Kusuda et al, 2007;Mantovanelli & Ridd, 2006;Bürger & Wendland, 2001;Garrido, Bürger & Concha, 2000). Most studies in the literature are related to the description of tidal and marine sediments.…”

Section: Semi-empirical Modelmentioning

confidence: 99%

Settling Suspensions Flow Modelling: A Review

Silva

Garcı́a

Faia

et al. 2015

KONA

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In spite of the widespread application of settling suspensions, their inherent complexity has yet to be properly predicted by a unified numerical model or empirical correlation, and usually industries still possess customized charts or data for their particular suspension. This is, clearly, rather inefficient and can lead to oversized dimensioning, low energy efficiency and even operation limitations/difficulties. In this manuscript a review of empirical correlations, charts and numerical models that have been employed to predict the behaviour of settling suspensions is briefly described, providing information on the advantages and drawbacks of each method. Their evolution throughout the years: from Durand and Condolios correlations, to empirical models by Wasp, single phase simplifications with mixture properties by Shook and Roco, and to other Euler-Euler or Euler-Lagrangian numerical models, will be presented. Some considerations on recent particle migration and turbulence modification publications will be added. In addition, information about some current CFD application of LatticeBoltzmann and Discrete Element Method (DEM) will be given. Lastly, data from CFD modelling employed by the authors that is able to predict turbulence attenuation in settling flows with medium sized particles for different concentrations is reported.

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A Century of Research in Sedimentation and Thickening

Abstract: This paper provides a concise review of the contributions to research in sedimentation and

Cited by 56 publications

References 98 publications

Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

On basic equations and kinematic-wave theory of separation processes in suspensions with gravity, centrifugal and Coriolis forces

Settling Suspensions Flow Modelling: A Review

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