Particle movement in the spheronizer – Experimental investigations with respect to the toroidal and poloidal direction

Oberservation of particle movement during wet granulation is crucial for identifying granulation mechanisms, process optimizations and troubleshooting. An example of such a process is spheronization, which is commonly used as a wet granulation technique to produce spherical, pharmaceutical pellets. Due to the dense particle bed, measurements of poloidal pellet velocities remain a challenge and have not been yet been reported in literature. In this work, a modelling approach was used in combination with particle image velocimetry (PIV) and mixing progress as a surrogate parameter to obtain information about the movement inside the pellet bed, including those parts not visible from outside the pellet bed. A good agreement between the experiment and the simulation was found. Regions of low poloidal velocities were found in both experiments and simulations. The initial pellet shape was not identified as a significant influence on the mixing progress. [Display omitted] •experimental measurement of movements in a dense particle bed is possible.•simulations provide acceptable representations of movement in a spheronizer.•Average pellet velocities in a spheronizer are dependent on the plate diameter.