Analysis of radial segregation of granular mixtures in a rotating drum
Saikat Chakraborty1 - Prabhu R. Nott1 - J. Ravi Prakash2
1 Department of Chemical Engineering, Indian Institute of Science,
Bangalore 560
012, India
2 Department of Chemical Engineering,
Indian Institute of Technology Madras, Chennai 400036, India
prnott@chemeng.iisc.ernet.in
Received 4 June 1999 and Received in final form 28 September 1999
Abstract
This paper considers the segregation of a granular mixture in a rotating
drum. Extending a recent kinematic model for grain transport on sandpile
surfaces to the case of rotating drums, an analysis is presented for
radial segregation in the rolling regime, where a thin layer is
avalanching down while the rest of the material follows rigid body
rotation. We argue that segregation is driven not just by differences in
the angle of repose of the species, as has been assumed in earlier
investigations, but also by differences in the size and surface properties
of the grains. The cases of grains differing only in size (slightly or
widely) and only in surface properties are considered, and the predictions
are in qualitative agreement with observations. The model yields results
inconsistent with the assumptions for more general cases, and we speculate
on how this may be corrected.
PACS
47.55.Kf Multiphase and particle-laden flows -
83.70.Fn Granular solids
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
