RECENT WORK ON FLUIDIZED-BED PROCESSING OF FINE PARTICLES AS ADVANCED MATERIALS

New processes for the production of high-performance particulate materials are reviewed, with their implications for fluidized bed technology. (i) Ultrafine particles can be fluidized if small agglomerates are spontaneously formed in a bed. Addition of coarse particles as turbulence promoters and mechanical vibration of the bed are useful to attain stable fluidization with cohesive particles. (ii) Entrainment is an important means to remove reacted fines continuously from the dense bed or to feed raw fines into the dilute reaction zone. (iii) Thermally activated chemical vapor deposition (CVD) has been utilized successfully to produce composite particles. Non-equilibrium plasma CVD is promising when the bed temperature must be kept low, as in surface modification of fluorescent particles and pigments. (iv) Studies on reaction kinetics and reactor optimization are insufficient. The modelling of a fluidized CVD reactor has been developed only for the production of polysilicon particles.