Restitution coefficient in grinding process: experimental determination and numerical analysis using DEM

The DEM technique has been widely employed to study the mechanical behavior of granular systems in several engineering fields. However, this approach has some drawbacks, such as the need to specify the input parameters. This work aimed to measure experimentally the restitution coefficient (COR) of chrome steel balls and quartzite gravel by varying the particles sizes, the thickness of impact surface and the drop height. Afterwards, we analyzed how these measured restitution coefficient values influence on the grinding media dynamic inside a ball mill by DEM simulations. We observed a significant influence exerted by the variation of particle size and the surface thickness on COR. There was also a difference in the restitution coefficient values when the pairs particle-surface of different sizes were permuted. Furthermore, we quantify the effects of the different experimental COR values on number of collisions and energy of the collisions in a ball mill.