Contact person: Greta Fragnière
A large part of global energy demand is spent on comminution during the processing of solids in different industries. Fine grinding, i.e. comminution in the lower micrometer and sub-micrometer range, is thereby increasingly gaining importance, not only in the chemical and pharmaceutical industry, but also in mineral processing and ceramics industries. Stirred media mills are especially suited for wet ultra-fine grinding and dispersing.
For a predictive model of grinding or dispersing progresses considering dynamically changing operating parameters the distinction between machine and material function is necessary. On the one hand, the process is determined by the fracture properties of particles in the mill feed. On the other hand, there are machine parameters such as the stirrer geometry, the material and size of grinding beads, and the stirrer speed, which significantly affect the grinding or dispersing process. In a continuous process, the volume flow and the control strategy add to the major influencing factors. In the ultra-fine grinding in stirred ball mills operated wet the viscosity of the medium may vary with the particle size distribution and concentration of solids leading to a change in the grinding bead distribution and thus different stress conditions. For dynamic process simulation, it is therefore crucial that the machine function is determined by mechanistic models. These include, for example, a transport model, a power consumption model, a material distribution model and a stress model.
The aim of the project is to create a predictive, dynamic model to predict the particle size distribution in the fine grinding and dispersion. In this case, the flow behavior of the product, the product carrier, and the axial grinding bead distribution has to be taken into account. In addition a method for calibration of material parameters for fine grinding is developed.
This project is funded by the German Science Foundation (DFG) within the priority program “Dynamische Simulation vernetzter Feststoffprozesse” (SPP 1679).
Publications related to the project:
Beinert, S.; Fragnière, G.; Schilde, C. und Kwade, A. (2015) Analysis and modelling of bead contacts in wet-operating stirred media and planetary ball mills with CFD–DEM simulations. Chemical Engineering Science 134: 648-662.
Beinert, Stefan; Schilde, Carsten; Gronau, Greta und Kwade, Arno (2014) CFD-Discrete Element Method Simulations Combined with Compression Experiments to Characterize Stirred-Media Mills. Chemical Engineering & Technology 37(5): 770-778.