Impact of grinding aids and process parameters on dry stirred media milling

Abstract

The demand on minerals with increasing product fineness is currently rising in many industrial applications. Especially in dry grinding processes, fine powders are difficult to produce and to handle. Particle-particle attractive forces, which become more decisive with decreasing particle size, lead to a higher extent of agglomeration, material adherences and a more cohesive flow behavior. As a consequence, dry fine grinding processes demand large quantities of energy due to the amount of applied energy that is dissipated into heat. Current approaches for improving the energy efficiency mainly cover the improvement of a) machine equipment and b) the material behavior. The main focus of this study was to investigate both aspects within one single study: On the one hand, dry fine grinding of limestone was investigated in a dry operated stirred media mill, which is a promising and emerging option for dry fine grinding applications. On the other hand, the impact of the particle stabilization by liquid grinding aids on the grinding performance was evaluated. It was demonstrated that the grinding mechanism inside the mill depends on both the mill parameters as well as the powder flow behavior. Therefore, it is of crucial importance to adjust the mill parameters to the applied grinding aid when it comes to dry fine grinding in media mills.