ANOMALIES IN AVALANCHE MIXING OF GRANULAR MATERIAL AT HALF FILLING

Two fractions of granular material mix in a drum rotating slowly about its longitudinal axis arranged horizontally. The drum is filled not t o full capacity, and mixing occurs at each moment of time only on the free surface of material. It is shown that in a half-filled drum the m aterial will never reach uniformly mixed state. Near this critical poi nt, the inverse characteristic mixing time is proportional to delta(2) ln(\delta\(-1)), where delta is the deviation from the half-fill leve l. (C) 1997 American Institute of Physics.