(201d) Transport and Mixing of Cohesive Granular Material in a Continuous Bladed Mixer: Effect of Cohesion, Impeller Speed, and Fill Level

The recent drive towards continuous drug manufacturing under FDA's Process Analytical Technology (PAT) initiative demands better understanding of flow and mixing of powders in continuous blenders. This work simulates cohesive particles in a continuous blender periodic slice using the discrete element method (DEM). The influence of inter-particulate cohesion at various impeller speeds (Froude number) is reported. Even though increasing cohesion does not significantly change the axial flow rate, mixing rates in the transverse plane and axial direction are affected. Mixing is generally enhanced for slightly cohesive materials, similar to trends observed in batch mixers, even though the responsible mechanisms are different. Changes in fill level are also shown to affect axial transport rates and mixing. These results suggest that controllable operating conditions such as feed rate and Froude number need to be adjusted for different powder formulations to obtain optimal mixing performance.