A new method for simulation of comminution process in mills

Recently, we developed a CFD-DEM model in which empirical comminution functions (strength distribution, selection function, breakage function and fatigue function) were implemented. In this way an accurate simulation of the size reduction process can be achieved. However, this simulation requires a very long run time that might prevent the use of the simulation for practical cases. Therefore, we present in this paper a new procedure to describe the comminution process in a jet mill, although the same procedure might be applied to any size reduction system. The new procedure is using the same comminution functions applied to any particle that enters the mill. However, there are two parameters missing in order to run the breakage procedure, they are the impact velocity and the impact frequency distributions. Both functions were derived from DEM\CFD simulations of the jet mill, ignoring the particle breakage. In this way, time is required to run the CFD-DEM simulations to determine the impact velocity and frequency distributions. However, by ignoring the breakage events the run time is much reduced. Moreover, once these distributions are defined for a defined mill configuration as a function of particle size and air flow rate, simple and fast simulations can be performed with the same distributions and a variety of operating conditions. In addition, the classification function is used in the new method to define the particle cut size. The particles which are smaller than the particle cut size are exiting the jet mill. The results of new simulation method were compared to experimental results of the jet mill.