Simulation and experiments of mixing and segregation in a tote blender

Experimental and computational investigation of mixing and segregation of granular material in a tote blender was carried out. The discrete element method (DEM) was used to simulate flow of spherical, free-flowing particles where the results of the computations were compared to blending. Computational results are compared to blending experiments of monodisperse and bidisperse systems using spherical glass beads in a 1:1 scale. Although some discrepancies were observed, DEM simulations illustrated good agreement with experimentally measured mixing and segregation rates for different fill levels and loading conditions. The effects of blender geometry on particle velocities and flow patterns were examined using DEM. The presence of a hopper and bin section, as well as the axial offset proved to introduce greater axial mixing rates that would be expected from pure dispersion. Vibrated experiments showed better agreement than not-vibrated experiments, indicating that modeling of friction forces needs to be further improved to enhance the accuracy of DEM methods. © 2005 American Institute of Chemical Engineers AIChE J, 51: 836–844, 2005