Particle segregation in a rotating drum with inner segmentation ring pair

A pair of the inner segmentation (IS) rings is inserted in a rotating drum. The effects of the location and size of the rings on the axial and radial segregation patterns are studied. When the IS ring pair locates outside the end wall shearing zone of 10 particle diameter, the ring shearing independently affects the local mixing. The rings concentrate the larger particles at the bed periphery and smaller particles in the core, increasing the band number and degree of mixing. The drum mixing index monotonically increases with the ring width. There exists a critical IS ring width causing a 2-h long-term segregation pattern changing. The critical ring width in a 40% fill drum is ca. 30 particle diameter, covering 52% of the transverse bed area.