A discrete element method investigation within vertical stirred milling: Changing the grinding media restitution and sliding friction coefficients

The paper investigates the effects of changing the particle-particle restitution and sliding friction coefficients of grinding media within a vertical stirred mill using the discrete element method (DEM). A 190 mm diameter attritor mill containing 3491 particles was simulated to explore combinations of parameter values, across five rotational velocities. The results show variation over the parameter space, becoming significant if the sliding friction falls below 0.1, as single-body motion forms from the reduced resistance. Above this, forces are sensitive to changes in both restitution and friction, particularly the latter. Higher rotational velocities also lead to increased effectiveness. However, it also comes at a cost of increased power draw. The results suggest that a compromise would need to be made between effectiveness and efficiency, but could also form a basis for making simplifying assumptions in more complex scenarios. A template version of the simulation can be found at https://github.com/darhyme147/ligggghts_stirred_mill_template.

Automated summary

This paper investigates the effects of changing the particle-particle restitution and sliding friction coefficients of grinding media within a vertical stirred mill using the discrete element method (DEM). The results show that if the sliding friction falls below 0.1, single-body motion forms from reduced resistance. Forces are sensitive to changes in both restitution and friction, particularly the latter. Higher rotational velocities also lead to increased effectiveness.