Axial mixing and segregation were investigated by use of a "rapid section-cutting" fluidized bed. The axial variation oi particle size distribution

mean size and local voidage was measured. The particle motion was found to have random behavior. A random walk mode] was developed by using the Markov Process to characterize mixing and segregation of fluidized wide sizedparticles. Two systems

ilmenite and quartz

were tested with particle size between 0.04 and 0.40mm. The results showed that the minimum fluidization velocity

expansion behavior ot particles

the axial variation of particle size distribution

mean size and local voidagc could be predicted by the model accurately and convienently.