Dynamic process models for ultra fine grinding and dispersion

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The main objective of the DynSim-FP 1679 program is to provide numerical tools for a dynamic simulation of networked solid-state processes with different devices and machines in the field of solid-state process engineering. In particular, stirred media mill are used for fine comminution and dispersion. Partially empirical but also physically based models exist in order to model this process by describing the transport behavior, the power input and the comminution behavior.To date, these models have been limited to stationary mill operation in the area of the fine grinding. Hence, there are no models for stirred media mill that allow a predictive dynamic simulation of the particle size distribution or particle shape change under variations in material and operating parameters. In a dynamic simulation, the process model must be able to reproduce the product particle size distribution subjected to changes in operating parameters as it occurs during the operation of the mill. In the context of this project, this goal is to be achieved by coupling the population balance model with a stress and material model for continuous mill operations.Throughout the first funding period, the central focus was on the conception and coupling of the models for the description of comminution, viscosity and power consumption for batch operation systems. Within the second fund period, the model has been expanded to continuous operation systems via a material transport and material distribution model. Additionally, a method for calibrating the model parameters, specially breaking rate and breaking function, has been established in particular for applied model parameters and defined produced silicon dioxide aggregate systems. The breakage function differs significantly during dispersing processes and must be considered individually. The material function for the used aggregate systems as well as its transfer to a commercial aggregate system is to be developed in the third funding period. In addition, the integration of the continuous process model into the SPP simulation environment and model extansion should include the capture probability of product particles, multiple stresses and particle shape change. For the representation of the dynamic behavior, the continuous operating mill is also connected with a mixing vessel and a classifier.