Applicability of a scale-up methodology for wet granulation processes in Collette Gral high shear mixer-granulators

This study investigates the extension of a scale-up methodology based on di mensionless power relationships, to a series of vertical mixer-granulators in which the bowl is removable, i.e. both impeller and chopper blades are m ounted on top-driven vertical shafts positioned through the lid. Granulatio n runs were carried out in several bowl sizes belonging to the series of Co llette Gral mixer-granulators, ranging from 8 to 6001 capacities. It was sh own that under certain conditions a common scale-up master curve could be d rawn from the data gathered for each bowl, thus permitting the use of such a curve for the determination of mixer-granulator power consumption at a de fined granulation end-point. The results also helped to clarify the concept of similitude, both geometrical and dynamic, which is implied in the metho dology. The importance of wall slippage (as promoted by the insertion of a PTFE lining into the bowls) and batch size are illustrated. (C) 1999 Elsevi er Science BN. All rights reserved.