MIXING OF GRANULAR MATERIAL IN A DRUM MIXER UNDERGOING ROTATIONAL ANDROCKING MOTIONS - II - SEGREGATING PARTICLES

This study examines mixtures of particles of unequal sizes in a cylind rical drum both for pure rotation and rotation with vertical rocking. These motions generate mixtures with complex patterns. Such structures are frozen in situ, sliced, and characterized quantitatively using im age analysis. For short times, segregation patterns observed in these experiments differ from those anticipated from previous studies in the literature; the large particles tend to concentrate in segregated cor es. For long times, the larger particles migrate to the ends of the cy linder, approaching the more commonly observed banding segregation pat terns. Under some conditions, near-homogeneous structures are generate d, but such systems are meta-stable; additional mixing time results in a mon strongly segregated system. (C) 1998 Elsevier Science S.A. All rights reserved.