(270e) Population Density Dependence of Mechanical Multi-Particle Interactions

Mechanical interactions between particles are important in many processes involving granular materials.  Dense phase dry milling processes in particular are sensitive to mechanical interactions at the particle ensemble scale.  During milling, particles transmit forces amongst themselves and cause breakage if the resultant local stresses are high enough.  However, breakage is not only dependent on intrinsic particle properties, but also on the population density due to mechanical multi -particle interactions.  To elucidate the effects of mechanical multi -particle interactions, numerical experiments were conducted by means of discrete element modeling (DEM).  Mono- , binary- , and poly -dispersed mixtures of particles were subjected to vibration in order to determine their influence on the distribution of impact energies and contact forces.  The nature of the multi- particle interactions can be used to explain some interesting breakage kinetics.  Results may also have a broader relevance to many other processes including that of particle dry-coating.