6 Dynamic Process Models for Fine Grinding and Dispersing
233
Fig. 30 Median and x 84 value for the particle size at the product outlet (below) responding to a
step function of the flow rate (above)
8 Conclusion
In this contribution two types of horizontal stirred media mills (with and without
deflecting wheel) were investigated experimentally and with simulation in order to
describe relevant machine parameters for a dynamic process model for stirred media
mills. Coupled CFD-DEM simulations were performed to determine the contact frequency and stress energy of the grinding bead collisions. The unresolved simulations
showed good agreement to existing models for describing stress energy. The distribution of different collision types such as normal collisions, shearing and rolling
could be derived to be used as input parameter for resolved simulations. In these
the capturing probability of product particles between approaching grinding beads
were investigated, depending on the proportion of the above mentioned collision
types. Principle insights could be gained such as increased capturing probabilities
for shearing and rolling motion. The capturing probability in combination with the
collision frequency and stress energy delivers the relevant machine parameters for
flow sheet simulations.
233
Fig. 30 Median and x 84 value for the particle size at the product outlet (below) responding to a
step function of the flow rate (above)
8 Conclusion
In this contribution two types of horizontal stirred media mills (with and without
deflecting wheel) were investigated experimentally and with simulation in order to
describe relevant machine parameters for a dynamic process model for stirred media
mills. Coupled CFD-DEM simulations were performed to determine the contact frequency and stress energy of the grinding bead collisions. The unresolved simulations
showed good agreement to existing models for describing stress energy. The distribution of different collision types such as normal collisions, shearing and rolling
could be derived to be used as input parameter for resolved simulations. In these
the capturing probability of product particles between approaching grinding beads
were investigated, depending on the proportion of the above mentioned collision
types. Principle insights could be gained such as increased capturing probabilities
for shearing and rolling motion. The capturing probability in combination with the
collision frequency and stress energy delivers the relevant machine parameters for
flow sheet simulations.