Investigating the impact of grinding media shape on load behaviour and mill power in an industrial-scale tumbling mill using DEM simulation

The shape of grinding media significantly influences mill performance, including load behaviour, power draw, and toe/shoulder positions. Prior research has paid limited attention to the impact of grinding media shape variation on industrial-scale tumbling mill performance. Cylindrical shape media produce a narrower desired product size distribution compared to spherical shape media. In the present study, the Discrete Element Method (DEM) based approach with a superquadratic shape model was used to analyse the effect of cylindrical versus spherical media on industrial-scale tumbling mills. Additionally, the impact of the cylindrical media size and total media mass variation on tumbling mill performance was studied in detail. The developed DEM model was validated both qualitatively and quantitatively against experimental data reported in the published literature for laboratory scale tumbling mill. The simulation results depict that the cataracting effect is greater and the cascading effect is reduced with the use of cylindrical media due to the change in contact dynamics from point contact in spherical media to line contact in cylindrical media. Additionally, cylindrical media of the same diameter as the spherical media consume more power and generate higher average force. Reducing the total mass of cylindrical media by around 15% can achieve power consumption and average force comparable to spherical media. These findings provide useful insights for replacing spherical media with cylindrical media in industrial tumbling mills to overcome the overgrinding issue with spherical media for soft and friable materials.