Simulation of a continuous granular mixer: Effect of operating conditions on flow and mixing

Continuous particulate blending has received much attention in the recent decade as it provides a more economical and efficient alternative over batch blending for large scale manufacturing. The influence of operating conditions in continuous blenders is not well understood quantitatively, even though qualitative parallels can be drawn with batch blending for similar geometries. This work investigates the influence of fill level and impeller rotation rate (Froude number) in a horizontal bladed continuous blender using the discrete element method (DEM). Particle flow within the blender was found to be strongly dependent on the Froude number and fill level, with distinct fluidized and quasi-static regimes at smaller fills. The axial flow rates showed significant variation with Froude number and fill, and also showed considerable variation over the course of a shaft revolution. Favourable mixing was obtained at smaller impeller rotation rates for larger fills, but at larger impeller rotation rates for smaller fills.