Validation of DEM simulations for a drum-type agitation mill using particle velocities measured by 3D PTV

We found that the impact energy calculated by discrete element method (DEM) simulation can be used to explain the liberation of materials from electronic scrap (e-scrap) in a previous study; however, the absolute value of the impact energy had not been validated. Thus, we attempted to confirm the reliability by considering the particle velocity, which is highly related to impact energy. The comminution experiment was conducted using a drum-type agitation mill, and the particle velocity was measured by 3D particle tracking velocimetry (PTV) based on moving body analysis. The particle velocities for both the DEM simulation and PTV were compared for two types of particles, a non-breakable steel component and a connecting component that represents a breakable form of e-scrap. As a result, the particle velocities obtained from the two methods were within a relative error of 10% for the steel component, and thus the reliability of the impact energy was indirectly confirmed. In contrast, for the connecting component, the particle velocity from the DEM simulations was more than 50% higher, suggesting the influence of fracture energy. By calibrating the DEM simulation based on the particle velocity from PTV, the energy efficiency of fracture was estimated to be approximately 60%.