Design and optimization of stirrer and mixer design for the correct mixing of pharmaceutical powders through DEM

Abstract

Mixing of granular materials is an important process for pharmaceutical industries. In this study, a quantifiable calculation method was suggested to determine the final mixing degree of the mixture. Based on that, the effect of the stirrer design, rotational speed, powder density, cohesivity, material ratios, and particle movement in the chamber guided through different designs of deflectors on the final mixing quality is examined. The results show that increasing the stirring speed, generates better mixing quality. However, introducing a varying rotational speed mode improves the mixing degree specially for binary mixtures with high relative densities. The improvement of the mixing with the number of contacting blades is observed. Finally, the introduction of a simple deflector drastically enhances the mixing quality and enables the feeding into the chamber, which is key for continuous operation with cohesive powders, making the process more stable and efficient by using more of the mixing volume.