Granulation of cohesive Geldart group C powders in a Mini-Glatt fluidized bed by pre-coating with nanoparticles

Fluidized beds are widely used for particle coating and granulation in the pharmaceutical and chemical industries because of their excellent mixing properties, high heat and mass transfer rates, and ease of scale-up. However, a conventional fluidized bed cannot be used for handling fine cohesive particles (less than 40 μm) due to their poor fluidizability. In this paper a proprietary technique, which involves the use of nanosized particles to pre-coat the fine particles to be granulated, is developed for improving the fluidization behavior of cohesive powders. Utilizing this technique, experiments on granulation of fine particles (15 μm cornstarch) are performed using a Mini-Glatt fluidized bed unit. After precoating the cohesive cornstarch particles can be stably fluidized in the Mini-Glatt device. By adding a top spray binder solution of PVP in water, granules having desired properties (average size and size distribution, flowability, density, etc.) can be obtained through this novel approach. The effect of various operating variables to control the properties of the final granules is also investigated.