(6a) Quantifying the Effects of Process Conditions On Liquid Impact On Powder Beds towards Granule Formation

Authors: 
Kayrak-Talay, D., Purdue University
Emady, H. N., Arizona State University
Litster, J. D., Purdue University


The aim behind the idea of separating the rate processes (i.e. wetting and nucleation, consolidation and growth) taking place during wet granulation is to have a better control on the final granule attributes. A new design was developed that incorporates the wetting and nucleation, and also the consolidation and growth mechanisms in two separate pieces of process equipment. The first piece of equipment is a conveyor belt apparatus that achieves monosized nuclei granules from monosized drops on a bed of powder. Following nucleation, the granules and fines are transferred to a tumbling drum, where they densify and grow by layering of the fines. Initial step of this study requires determining the nucleation mechanisms of binder- powder systems that are under investigation. Based on the information gathered from stationary bed experiments, initial operating conditions of the conveyor belt apparatus is determined. The characteristics of binder droplet contact with the moving powder bed and nuclei formation on the conveyor belt are further investigated to optimize the operating conditions of the process. The nucleation characteristics of two different model powders on the conveyor belt will be presented along with the effects of operating conditions on the granule morphology and size.