Journal ArticleDOI
Dewatering of flocculated suspensions by pressure filtration
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TLDR
In this paper, a nonlinear model for flocculated suspensions under the influence of an applied pressure is proposed, based on the assumption that when the volume fraction is high enough, the network formed from the aggregation of flocs possesses a compressive yield stress Py(φ) that is a function of local volume fraction φ only.Abstract:
Pressure filtration is an important method for removing liquids from a suspension. Previous work used linear models or applied to stable suspensions. Nonlinear models for flocculated suspensions are studied here. The equations governing the consolidation of flocculated suspensions under the influence of an applied pressure are based on the assumption that when the volume fraction is high enough, the network formed from the aggregation of flocs possesses a compressive yield stress Py(φ) that is a function of local volume fraction φ only. There are two modes of operation of the pressure filter—the fluid flux or the applied pressure is specified—and both of these are studied. The resulting nonlinear partial differential equations involve the time‐dependent piston position, and in the case of the suspension being initially unnetworked, another internal moving boundary below which the suspension is networked. The small time behavior of these systems is obtained with an asymptotic method. In general, at later times, the solution can only be found numerically and an algorithm for doing this is discussed. The important parameters and properties of the filter cake are described. The results suggest various ways of controlling the filtration process, which may be useful in the manufacture of ceramics.read more
Citations
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References
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Journal ArticleDOI
Sedimentation in a dilute dispersion of spheres
TL;DR: In this article, the authors considered a large number of identical small rigid spheres with random positions which are falling through Newtonian fluid under gravity and determined the mean value of the velocity of a sphere (U).
Journal ArticleDOI
The consolidation of concentrated suspensions. Part 1.—The theory of sedimentation
Richard Buscall,Lee R. White +1 more
TL;DR: In this paper, the concentration or consolidation of suspensions of fine particles under the influence of a gravitational field has been analyzed and a constitutive equation is suggested for irreversibly flocculated suspensions undergoing consolidation which embodies the concept of a concentration-dependent yield stress Py(ϕ).
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Moving Boundary Problems in Heat Flow and Diffusion
Journal ArticleDOI
The rheology of strongly-flocculated suspensions
TL;DR: In this paper, the authors investigated the rheology of strongly-flocculated dispersions of colloidal particles in a continuous network and showed that these networks possess a true yield stress in both shear and uniaxial compression (as realised in a centrifuge).
Journal ArticleDOI
The resolution of shocks and the effects of compressible sediments in transient settling
TL;DR: In this article, a quantitative theory covering the full range of processes from transient settling of large, stable particles to the slow consolidation of flocculated suspensions of submicron particles is proposed.
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