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Insights in Scaling and Optimization of Ball Mill Operations - a Discrete Element Method Based Approach

Joerg Theuerkauf, Solids Processing, The Dow Chemical Company, Freeport, TX 77566 and Kaustubh S. Mujumdar, Dow Chemical International Private Limited,, Pune, India.

This paper aims to provide an understanding on the dynamics of grinding media in the ball mills using a Discrete Element Method (DEM) approach. A three dimensional DEM slice element model was developed to analyze the grinding media motion in ball mills.

The developed framework was used to predict the center of mass of the charge in the mill to subsequently predict the power draw of the mill. These predictions compare favorably with theoretical and in plant observations for ball mills over a range of fill levels and rotational mill speeds. The simulations show that the inclusion of the center of mass term in the scale-up equations is important for the correct prediction of the power draw when scaling ball mills. Furthermore, the time averaged collision intensity and frequency of the grinding media was analyzed. The performance of the mill was gauged by spatial contact force distributions in regard to possible wear at the ball mill cylinder when the fill level, rotational mill speed, media diameter and lifter shapes were varied. These results were used to identify optimal operating conditions for the mill.