Journal ArticleDOI
The consolidation of concentrated suspensions. Part 1.—The theory of sedimentation
Richard Buscall,Lee R. White +1 more
TLDR
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).Abstract:
The concentration or consolidation of suspensions of fine particles under the influence of a gravitational field has been analysed. The rate and extent of consolidation depends upon a balance of three forces, the gravitational driving force, the viscous drag force associated with flow of liquid in the sediment and a particle or network stress developed as a result of direct particle–particle interactions. In the case of colloidally stable suspensions, this particle stress is the osmotic pressure of the particles; in the case of flocculated or coagulated suspensions, it is the elastic stress developed in the network of particles. A constitutive equation is suggested for irreversibly flocculated suspensions undergoing consolidation which embodies the concept of a concentration-dependent yield stress Py(ϕ). This is then used to analyse the sedimentation behaviour of flocculated sediments and to derive expressions for the initial sedimentation rate. The initial rate of change of sediment height with time in a uniform gravitational or centrifugal field is given approximately by: [graphic ommitted] where B=Δρgϕ0H0/Py(ϕ0), u0 is the sedimentation rate of an isolated particle, ϕ0 is the initial (uniform) volume fraction of solids, r(ϕ0) is a dimensionless hydrodynamic interaction parameter, Δρ is the difference in density between solid and liquid, g is the gravitational or centrifugal acceleration and H0 is the initial sediment height. The theory accounts correctly for the equilibrium consolidation behaviour of strongly flocculated suspensions, and preliminary experimental data suggest that it is not inconsistent with their dynamic behaviour. The estimation of the yield stress Py(ϕ) from a batch centrifuge experiment is also described.read more
Citations
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Book ChapterDOI
Influence of physicomechanical properties on the rheology and stability of magnetite dense media
TL;DR: In this article, the rheology of magnetite suspensions is investigated as a function of physicomechanical properties such as yield stress and plastic viscosity, and the presence of a network also affects sedimentation behavior of a suspension.
Dissertation
The impact of desilication products on the flocculation and sedimentation properties of bauxite residue
Understanding rapid dewatering of cellulose fibre suspensions
TL;DR: In this article, the authors assess the suitability of a well-established modeling approach, referred to as the base model, at capturing the one dimensional dewatering behaviour of cellulose fibre suspensions seen experimentally.
Journal ArticleDOI
In situ nondestructive sediment characterization and resuspendability evaluation of concentrated aqueous paliperidone palmitate suspensions in prefilled syringes by low-field one-dimensional pulsed-field gradient NMR profilometry
Wuxin Zhu,Lien Vermeir,Ruxandra Govoreanu,Katrien Verbruggen,Tina Ariën,Arne Verliefde,Paul Van der Meeren +6 more
TL;DR: The study shows that both active ingredient particle size distribution and storage temperature had significant effects on the sedimentation rate and the resuspendability of the suspensions.
Journal ArticleDOI
Particles with tunable wettability for solid-stabilized emulsions
Abstract: We demonstrate that the wettability of cosmetic grade, silica-coated titanium dioxide nanoparticles may be tuned by simply soaking them in a cyclic silicone oil. This allows for tuning the type of emulsion that they stabilize, from oil-in-water to water-in-oil. By analyzing the sedimentation of water-in-oil emulsions, the effect of the soaking time (wettability) on drop size and drop-drop interactions was investigated. From centrifugation experiments performed up to emulsion breakage, we obtain an effective water-oil interfacial tension for the particle-loaded interfaces, which indicate lateral particle-particle interactions. Finally, we demonstrate that the proposed particle functionalization is terminated upon addition of water followed by emulsification. In addition, it is irreversible and can be accelerated through heating.GRAPHICAL ABSTRACT (Figure presented.). (Less)