(67d) Mapping of Nucleation Mechanisms for Regime Separated Granulation

Authors: 
Emady, H. N., Arizona State University
Kayrak-Talay, D., Purdue University
Schwerin, W. C., Honeywell


Wet granulation is the process of adding a liquid binder to a fine powder in order to get larger granules for improved particle properties.  This process is used in a variety of industries, including pharmaceuticals, food, agricultural chemicals, and detergents.  The typical industrial equipment used for this process includes high shear mixers, drums, pans, and fluid beds.  Currently, many of the granulation rate processes occur simultaneously in industrial applications, making it difficult to control product properties, such as size and density.  These three rate processes include wetting and nucleation, consolidation and growth, and breakage and attrition.  The aim of this research is to physically separate the different rate processes to get better control of the product granule attributes.

The first step of granulation is nucleation, and drop controlled nucleation is the most desirable form.  In this case, one drop forms one granule.  Single drop granule experiments with a syringe and a dish filled with powder are used to simulate drop controlled nucleation.  Many model powders were used in single drop granule experiments, with a variety of binders and process conditions.  The resulting nuclei granules were excavated, and their size and density were measured using a novel prism technique with image analysis.  The nuclei granule properties were then mapped to powder properties, binder properties, and process variables.  Different nuclei formation mechanisms occur for different combinations of these variables, explaining the formation of nuclei granules with varying properties.  The desired outcome is to be able to predict the nucleus formation mechanism and subsequent nuclei granule shape based on the knowledge of powder and binder properties, as well as process variables.