Analysis and simulation of wet-granulation processes

Background: Size enlargement by wet-granulation is one of the most important unit operation in several industrial fields: pharmaceutics, food processing, animal nutrition, agronomics, and so on. A lot of techniques have been used in order to measure the particle size distributions (PSD) and a few different approaches are available to model the PSD evolution during the process, mainly based on population balance equations (PBE). However, difficulties in both the activities (reliable measurement and robust modeling) have hindered their diffusion in industrial practice, keeping the granulation closer to an art than to a science. Methods: In this work, a fast and reliable method to measure PSD, based on dynamic image analysis (DIA) is presented and used in two case histories, one on a batch process on lab scale, and the other on a continuous process on plant scale. Significant findings: The evolution of PSD was successfully described by models based on PBE, confirming the validity and the usefulness of the two approaches (experimental/modeling). The resulting model could be used as a basis for the process analysis and - to some extent - to predict the system's behavior in different conditions.