Abstract. Spherical granules with a narrow size distribution are widely used in many pharmaceutical applications. Extrusion-spheronization is a well-established process to produce such pharmaceutical pellets. The cylindrical extrudates from the extrusion step are rounded in the spheronizer. The formation mechanisms inside of a spheronizer depend strongly on the particle dynamics. To describe the complex particle flow and interactions, the Discrete Element Method can be used. In our previous works the spherical particles during the last part of the spheronization process were studied. Since the pellets have a cylindrical shape at the beginning and undergo different stages of deformation during the rounding process, the objective of this study was the description of the influence of the particle shape on the particle dynamics. To predict the interactions of the pellets, their dominant plastic behaviour was described with an appropriate contact model and the material parameters were calibrated with compression and impact tests.

Particle Kinematics in Spheronization of Pharmaceutical PelletsFor the production of pharmaceutical pellets, a combined extrusion and spheronization process is widely used, where the particle kinematics strongly influences the rounding in the spheronizer. In this study, the particle kinematics of the actual pharmaceutical pellets was analyzed. For this purpose, material parameters, such as coefficient of restitution and rigidity while loading and unloading, were determined by pressure and impact tests. Based on these parameters, a contact model for the simulation of the particle movement was developed. The simulation results were validated with experimental investigations.

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