Investigation of Optimum Scale-Up of Media Stirred Mill Using the Discrete Element Method

Media stirred mills have been used in various fields to efficiently produce fine products. The scale-up of such mills is required to increase efficiencies and applications for industrial processes. Despite such circumstances, established scale-up laws remain unavailable, and scale-up has been conducted empirically. This study aims to propose essential requirements for the scale-up of a media stirred mill according to experiments and discrete element method (DEM) simulations. The experimental results were evaluated qualitatively by using particle size distributions of ground products and fitted using grinding kinetic theory as a quantitative evaluation. The grinding performance in the laboratory model was equivalent to the results using the scaled-up model (SU-model) with the modified Froude number, regardless of the rotation speed. DEM simulations identified the main factor that contributed to the agreement. The average collision energy of the media particles was almost identical. To set optimal conditions to fulfill this core requirement, the SU-model operation conditions need to follow the modified Froude number, and the intervals of each arm should be fixed to the same distance. These insights encourage the application of scaled-up media stirred mills.