Microgranulation of fine powders by a novel rotating fluidized bed granulator

A novel rotating fluidized bed system has been developed for fluidizing, granulating and coating cohesive fine powders to tailor their properties and functionalities. The system basically consists of a plenum chamber and a horizontal porous cylindrical air distributor, which rotates around its axis of symmetry inside the chamber. The pressure drop and minimum fluidization velocity of cohesive fine cornstarch powder (mass median diameter of 15 μm, Geldart Group C powder) were measured under various rotating conditions and the fluidization behavior was studied. The system was then used for wet granulation of the cornstarch powder and the effects of operating parameters on the granule properties such as granule size, size distribution, density and flowability were investigated. The experimental results indicated that the flowability of cohesive fine cornstarch was dramatically improved by the microgranulation resulting in spherical granules with a narrow size distribution while inhibiting the size enlargement.