(158d) Dry and Cohesive Powders in Vertical Axis High Shear Mixers Using Positron Emission Particle Tracking (Pept)

Vertical high shear mixers are predominately use in the pharmaceutical industry for granulation processes. An integral component in the understanding of granulation fundamental mechanisms such as nucleation, growth and breakage, is the powder flow behaviour within granulators. An investigation was made into the flow behaviour of dry and cohesive sand within a vertical high shear mixer, using Positron Emission Particle Tracking (PEPT) and torque analysis. Significant differences in flow behaviour were observed between dry and cohesive powders. The complexities of the powder flow are observed for a variety of formulation properties and operational parameters. Data on particle position, local velocities, accelerations and particle density presents a detailed view of powder behaviour however, a major drawback to the PEPT technology is that collisional velocities and forces cannot be measured directly which is useful for growth and breakage models. The objectives of the work are to produce a comprehensive "map" of particulate motion, to understand the effects of operating parameters on granulator performance, to devise better monitoring and end-point determination, and to improved designs of granulators.