Kaolin clay slurries were studied using a concentric cylinder viscometer and a 25.8 mm I.D. vertical pipe viscometer. Clay volume fraction was varied between 0.10 and 0.19 while the mass ratio of dihydrated calcium chloride (flocculant) to clay was maintained at 0.0010. Tetrasodium pyrophosphate (dispersant) was added to selected slurries. The Bingham and Casson models accurately represented laminar flow data and the parameters obtained with the two viscometers were in good agreement. The ability of the Wilson and Thomas, and Wilson and Addie models to fit the turbulent data varied with experimental conditions. Newtonian behaviour occurred with sufficient addition of dispersant. An irreversible increase in apparent viscosity was noted with slurries having volume fractions of 0.17 and 0.19.
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