Location: JHE 326H
Wet granulation is a ubiquitous process in any industry that handles fine powders. The product granules need to have well controlled property distributions (size, density and structure, content uniformity) in order that they possess the desired product attributes (resistance to attrition, caking and segregation, correct disintegration and dissolution profiles, compressibility, etc). As engineers, we require good models to predict the effect of formulation properties and process parameters on the generation of the property distributions. However, it is difficult to develop predictive models for continuous mixer granulation processes because of their complexity: complex formulations, complex powder flow fields and competing rate processes. Despite these challenges, significant progress has been made in this area in recent years. This seminar presents an overview of the work of our group in this area. Key rate processes and corresponding regime maps are defined. A compartment modeling approach for capturing most of the key physics is outlined, and two case studies from current research are presented: (1) Paste dispersion in a pin mixer for detergent granulation; and (2) modeling coupled consolidation and coalescence of enzyme formulations in a plough shear mixer. The process complexity begs the question: “Why not redesign the process to simplify it?”. This leads to the concept of regime separated granulation. A new approach to wet granulation in a Twin Screw Granulator (TSG) may be operated for regime separated granulation where different granulation processes are individually optimized in different sections of the screw. Some recent results from mechanistic studies of TSG are described and implications for optimizing the TSG are discussed.
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