Influence of Dispersed Phase Characteristics on Rheological Behavior of Suspensions

G. Matijašić and A. Glasnović

Abstract
The rheological behavior of clay and kaolin suspensions has been investigated in order to find possible effects of dispersed phase characteristics. Those effects were described using property functions. Clay particles were dispersed in water at four different solid volume fractions (6.4 %, 8.8 %, 11.4 %, and 14.2 %). At each solid volume fraction, six clay samples were used having different particle size distribution. Particle size distribution was described using LN distribution function where the measure of particle size range varied from 5.07 to 8.48 μm, and the measure of spread from 0.448 to 0.513. The same solid volume fractions were used for dispersing kaolin particles in the water. LN distribution function was also used for defining particle size distribution of six different kaolin samples. Measure of particle size range varied from 4.24 to 4.94 μm, while the measure of spread was ranging from 0.446 to 0.512. Rheological measurements using rotational rheometer showed that all used kaolin suspensions can be described using Herschel-Bulkley model while all clay suspensions showed Bingham behavior at any concentration. The obtained rheological parameters were correlated with solid volume fraction and external specific surface what resulted with two parameter models. Those models were joined into one equation that describes suspension plastic viscosity and enables viscosity estimations when solid volume fraction and external specific surface are known particle characteristics. Very good results were obtained for highly concentrated suspensions mostly used in process industry.

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Keywords
Bingham model, external specific surface, Herschel-Bulkley model, property function, specific pore volume, suspension rheology