Coating and granulation of fine particles using a standard fluidized bed

Fluidized beds are widely used for particle coating and granulation in pharmaceutical and chemical industries due to its high heat and mass transfer efficiency, and ease of scale-up. However, the conventional fluidized bed cannot be used for handling fine particles (less than 40 microns) due to their poor fluidizability. In this paper, a proprietary technique, which involves the use of nanosized particles to create nano-scale roughness on the surface of particles (much less than 40 microns) to be fluidized, is developed for improving the fluidization behavior of cohesive powders. Utilizing this technique, experiments on coating and granulation of fine particles (15 micron cornstarch and 15 micron aluminum) are performed using a standard fluidized bed unit. The results indicate that the fine particles can be stably fluidized after they are pre-treated with nanosized particles. Subsequently, very uniformly coated particles can be obtained through this novel approach. By changing the operating conditions, the same process can be used for granulation of fine particles. The effect of changing the operating variables on the properties of the final product is also investigated.