International Workshop Dispersion Analysis & Materials Testing 2014 – Session 6 Abstract
Berlin, Germany, 23-24 January 2014
www.dispersion-letters.com, © LUM GmbH
Centrifugal characterisation of suspensions in dewatering: permeability,
compressibility and elastic rebound
Dr Shane Usher
Research Fellow
Department of Chemical and Biomolecular Engineering
Melbourne School of Engineering
The University of Melbourne, Victoria 3010 Australia
T: +61 3 8344 5592 | M: 0413 720 758 | W: www.eng.unimelb.edu.au
Abstract:
Characterisation methods have been developed to characterise material properties that
describe the rate and extent of dewatering for particulate suspensions. These methods use
batch sedimentation at low solids concentrations (Lester et al. (2005)), centrifugation at
intermediate solids concentrations (Buscall and White (1987), Usher et al. (2013)) and pressure
filtration at high solids concentrations (Usher et al. 2001, Stickland et al. 2008) to characterise
properties over a broad range of solids concentrations. One shortcoming of these methods is
that they assume a compressed suspension or particle network will not re-expand once the
pressure is released. Observation of this re-expansion is difficult to observe when lowering the
pressure in a filtration device, but re-expansion readily observed when lowering the rotation
speed in centrifugation. Methods will be proposed to analyse this expansion data and describe
parameters that can be used to quantify this phenomenon for a range of industrial materials
including mineral slurries, wastewater sludges and red blood cells.
References:
Buscall, R. and L. R. White (1987). "The consolidation of concentrated suspensions." J. Chem.
Soc. Faraday Trans. I 83(3): 873-891.
Lester, D. R., S. P. Usher and P. J. Scales (2005). "Estimation of the hindered settling function
R() from batch-settling tests." AIChE J. 51(4): 1158-1168.
Stickland, A. D., C. Burgess, D. R. Dixon, P. J. Harbour, P. J. Scales, L. J. Studer and S. P. Usher
(2008). "Fundamental dewatering properties of wastewater treatment sludges from filtration
and sedimentation testing." Chem. Eng. Sci. 63: 5283-5290.
Usher, S. P., R. G. de Kretser and P. J. Scales (2001). "Validation of a new filtration technique for
dewaterability characterization." AIChE J. 47(7): 1561-1570.
Usher, S. P., L. J. Studer, R. C. Wall and P. J. Scales (2013). "Characterisation of dewaterability
from equilibrium and transient centrifugation test data." Chemical Engineering Science 93(0):
277-291.