The fluidized bed process presented in this paper is suitable for recovery of solids from
solutions in the form of granules. The solution is sprayed into the bed and as solvent
evaporates, solid material is deposited on the surface of fluidizing particles. During this
process, particle growth takes place by surface layering and/or agglomeration. A special
grinder is used in the fluidized bed to control particle growth by causing selective
disintegration of large particles. For steady state operation, the most important task is to
determine the existing particle size distribution in the fluidized bed. A special method
was developed to measure torque and stress fluctuations* in the bed of particles. Using a
correlation between torque and stress fluctuations and particle size, this method and
device can be used for direct control of the rotation speed of the grinder to produce
granules of given size in the fluidized bed. Results of torque and stress measurements
and their correlation to particle size are presented
