Discrete Element Study Mixing in an Industrial Sized Mixer

The mixing quality as function of the operating time is one major parameter to be considered for the design of industrial sized mixers. Different mixer types with different operating principles can be found for different special tasks, and the question about the proper quantity that quantifies mixing is still open. Computer simulations based on the Discrete Element Method (DEM) provide a close, detailed look inside the mixing device and process and thus a better understanding of the particle flow in the mixer. Therefore such simulations can be used for an improvement of the mixer design or operating conditions. DEM simulations allow the “online”- and “inline”-measurement of the mixing quality over time. But in mixers with a complex design it is not only interesting at which time a certain mixing quality is reached. It is also interesting to analyse which part of the mixing (either location in the device or process conditions) are of special importance due to a strong effect on the mixing process. Therefore, a time- and space-dependent analysis was developed, using several approaches for mixing-quality that can be found in literature. More explicitly, the particle numbers, the number of contacts between different particle-types, and the generalized mean mixing index (GMMI) have been examined. All have their regimes of reasonable use that will be discussed - the most promising approaches will be compared.