Published experimental results for the velocity-voidage relationship observed during fluidization and sedimentation of uniformly sized spheres in solid-liquid systems are compared and new experimental results are presented. Predictions of various published correlations that are available to describe this relation are compared with these experimental results and the inadequacy of most of the correlations is demonstrated. New correlations are suggested. The most reliable of these is based on a logistic curve and can be represented by the equation (l/R -A)/(B -UR) = 0.06Re,t+°2, where A = c4 14 and B = 0.8e128 for e < 0.85 or B = e2•65 for t > 0.85. UR = UJUX where Ut is the relative average velocity between particles and fluid, Ux is the terminal velocity of a single particle, Ret is the particle Reynolds number based on Ux, and c is the bed voidage.

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Published crystallization kinetics obtained in MSMPR crystallizers are reviewed, and measured nucleation and growth rates are compared on a common basis. In general, the range of variables studied (supersaturation, magma density, stirrer speed, etc.) for any given system is extremely limited. Experimental conditions, particularly those related to crystallizer hydrodynamics, are usually poorly defined and scale-up of kinetics on the basis of such results would not be possible. Conditions under which future laboratory studies should be made are suggested.

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