An Experimental and Theoretical Study of Ball-Wall Impact for DEM Modeling of Tumbling Mills

摘要

In recent years considerable effort has gone into applying distinct element methods to tumbling mills, and for good reason, as insights gained through DEM modeling promise significant improvements in both energy efficiency and general performance (Datta et al., 1999; Cleary and Hoyer, 2000; Rajamani et al., 2000; van Nierop et al., 2001). These DEM codes use soft contact between particles and generally assume the operation of normal and shear springs for motion perpendicular and tangential to the contact plane, with the latter shear spring giving way to simple frictional sliding under excessive shear forces (Cundall et al., 1999; Datta et al., 1999; Cleary et al., 2000). The springs can be linear or nonlinear. In addition several damping models have been invoked, perhaps the simplest, borrowed from fluid mechanics, being velocity dependent damping introduced independently to each spring system, creating normal and shear spring-and-dashpot contact systems. However, several features commonly present in DEM codes and of appreciable value in DEM modeling of coherent solids would seem to be inappropriate for the modeling of tumbling mills.