Molecular Dynamics of Comminution in Ball Mills
  We investigate autogenous fragmentation of dry granular material in rotating cylinders using two-dimensional molecular dynamics. By evaluation of spatial force distributions achieved numerically for various rotation velocities we argue that comminution occurs mainly due to the existence of force chains. A statistical analysis of theses force chains explains the spatial distribution of comminution efficiency in ball mills as measured experimentally by Rothkegel and Rolf. For animated sequences of our simulations see http://summa.physik.hu-berlin.de/~kies/Research/RotatingCylinder/rotatingcylind er.html 
Volkhard Buchholtz, Jan A. Freund, and Thorsten Poeschel