Controlling of Segregation in Rotating Drums by Independent End Wall Rotations

Abstract

We present in this study that particle segregation in rotating drums can be controlled by end wall rotations. While the end wall rotational speed dominates the time required for reaching the steady state, the rotational direction of the end walls determines the segregation patterns and the shearing zone size. New segregation patterns with two well-mixed regions close to the end walls are observed in the drums with the end wall rotates in the direction opposite to the cylindrical wall. The end wall rotation causes the formation of the local valley and hill next to the wall. Particles flow into the valley and down the hill causing the formation of the convective flow cell at bed surface. It is the difference of the axial velocities between the large particles and small particles close to the end walls separating the particles of difference sizes in the axial direction. The controlling of the end wall roughness and rotating directions effectively enlarge the size of the end wall shearing zone; resulting segregation patterns which are different from the previous simple segregation band patterns.

A study of the axial and radial competition segregation in a rotating drum with internal diameter changing

“…Some researchers changed the local particle dynamic angle of reposes near two end walls through the end wall roughness and shearing. The changed local particle dynamic angle of reposes shows new segregation patterns originating from the two end walls . Zik et al mixed binary particle in a drum with axial periodic radial modulations, and in a drum with axial helical modulations .…”

“…The changed local particle dynamic angle of reposes shows new segregation patterns originating from the two end walls. 23 Zik et al mixed binary particle in a drum with axial periodic radial modulations, and in a drum with axial helical modulations. 20 In the periodically modulated drum, the larger particles were locked in the neck region and the smaller particles aggregated in the belly region.…”

The tumbling mill rotation stability

“…In papers [2][3][4][5][6], the authors consider redistribution processes of the particles of the fill due to segregation associated with the complication of structure and the emergence of pattern formations with a loss of the motion stability.…”

“…In [6], the authors experimentally studied self-excitation of axial segregation of the fill caused by the independent relative rotation of the end walls of the chamber. They showed the effect of friction properties of the surface and the rate of shifting rotation of end walls on the noticeable change in the rate of particle displacement with the formation of elevations and hollows.…”