Model driven design of dense phase wet granulation processes

Wet granulation is the process of using a liquid binder to form well structured and well behaved granules from difficult to handle fine powders. Granulation allows the development of structured particulate products with defined attributes (flowability, strength, dissolution profile, etc) from a fine powder feed. The granulation process is a key step in the production of a wide range of products important to the UK manufacturing industries including pharmaceuticals (GSK, Astra Zeneca), food and consumer products (Nestle, Procter and Gamble, Unilever), agricultural and specialty chemicals (Syngenta). It is often the most problematic step and can cause problems in product quality, time to market, and increased cost through unnecessarily high recycle.
Despite its industrial importance, approaches to the design and scaling of granulation processes are still very empirical in practice. Transfer of knowledge to new formulations, or to new equipment designs is difficult at best. The goal of this project is to develop a compartment based modeling framework for design and scaling dense phase wet granulation processes. We will develop and validate coupled discrete element (DEM)/population balance (PB) models to predict the evolution of granule property distributions for dense phase wet granulators. The specific project objectives are to:
1. Develop compartment based multiscale design models for dense phase wet granulation processes;
2. Validate these models using laboratory scale batch high shear wet granulators; and
3. Develop gSOLIDS modules for batch and continuous wet granulators and use these to develop and implement educational case studies.

The project will develop a new collaboration between Sheffield University and Purdue University (USA) through the visiting scientist, Professor Jim Litster from Purdue. A key outcome of the project will be the development of new tools to support the UK manufacturing industries in efficient manufacture of structured particulate products.

The multiscale design models developed here will provide new tools for the rational design and scaling of dense phase wet granulation processes and help replace semi-quantitative and heuristic approaches that are currently used. While the model validation is specifically for batch, vertical axis HSWG, the approach and tools developed have much wider applicability including other geometries of high shear mixers, such as single and dual horizontal axis designs, other dense phase wet granulation approaches such as twin screw granulation, and fluidized systems. Wet granulation is an important, and often the most problematic, unit process for many products of great importance to the UK economy including pharmaceuticals (GSK, Astra-Zeneca), detergents and consumer goods (Unilever, Procter and Gamble), agricultural chemicals (Sygenta) and foods (Nestle). The new understanding will help reduce development costs and improve certainty in new product development in these industries.
This proposal takes advantage of a unique opportunity for Jim Litster (Purdue University), a renowned international expert in this field to work closely with Sheffield's excellent granulation research group led by Agba Salman and Mike Hounslow as a visiting researcher on this project. Professor Litster is an international leading expert on wet granulation with over 25 years experience in the field. In this time he has helped move this ubiquitous and troublesome process from a black art to an engineering science, with significant contributions to development of key regime maps for granulation processes and the development of mathematical models for engineering design and scaling of granulation processes (see previous track record and CV for more details). The project combines the recent exciting developments in multi-scale modeling from Litster and co-workers at Purdue with the unique experimental facility and expertise in PB modeling of the Sheffield group.
A key outcome of this work will be new, or improved, models of wet granulation processes available in the gSOLIDS software. This software is a product of PSE, a UK based technology software company. Thus the research is leading directly to tools that can be used by industry practitioners to improve process performance. These models will also form the basis for a series of case studies to be developed in a new text book co-authored by Professor Litster: Particulate Processes and Products (to be published by Cambridge University Press), allowing new developments to be part of the education of MS and PhD engineers and technologists in the UK, Europe and the USA. Both the software models, and the text book are expected to be released within the next two to three years.
A research fellow will be trained through this project and develop high level skills in both advanced computer modeling and laboratory skills with particulate materials. Strong interaction with PSE, as well as manufacturing companies who are potential users of the models will help the fellow develop good communication skills and networking for future job opportunities. More broadly, this project will enable the establishment of a new "across the pond" collaboration between Sheffield University and Purdue University, two of the internationally leading groups research into particulate processing, especially granulation. This collaboration is expected develop beyond this project to involve long term co-operation on research, research student exchange and education.