Numerical analysis of powder mixing dynamics in a ribbon mixer

Mixing of powders is one of the most important unit operations in many industries including chemical, food processing and pharmaceutical. A low mixing quality can compromise the final product and may result in loss of production and increased costs in the manufacturing process. There exists an extensive variety of mixers that can be mainly grouped into two categories: tumbling mixers and convective mixers. Among the convective mixers, the ribbon mixer is one of the most widely used in the industry. However, the mixing dynamics of ribbon mixer is complex and has not been resolved yet. In the last decade, Discrete Element Method (DEM) has been extensively used to try to understand the mixing process due to its ability to simulate the dynamics of the particles during the process. We present a numerical study on the mixing dynamics of powder in a ribbon mixer. DEM simulations were conducted varying different operating conditions including the level of filling, the speed of the blade and the initial loading spatial configuration. The particle data generated by DEM simulation were post-processed using of coarse-graining technique [1, 2]. This technique computes the bulk quantities of the powder and projects them onto a continuum field. This facilitates the investigation of the flow patterns and diffusion of the powder during the mixing process for the investigated operating conditions [3]. The results of the analyses provide new insight on the mixing dynamics in the axial and radial directions that ultimately can help to optimise the efficiency of the process.