Particle mixing and segregation behaviors in the rotating drums with adjacent axial segmentations in different speed directions

The axial mixing and segregation behavior of particles with different properties is a complicated movement process, whose mechanism is still indistinct. Consequently, it is very important to explore dynamic repose angle and flow characteristics of the particles along the axial direction during the mixing and segregation process. Focusing on the mixing and segregation phenomenon in the rotary drum, this paper studies the particle mixing and segregation behavior by changing the speed direction of adjacent axial segmentations. The results show that alternating axial segregation band characteristics can be formed in adjacent axial segmentations with same velocity direction, while the overall mixing degree is better under the condition of the opposite velocity direction. Although the different rotational speed directions of adjacent axial segmentations will cause opposite axial mixing and segregation phenomenon, the general rules of the dynamic angle of repose and axial flow velocity are similar in the rotary drum. In addition, the axial flow structure of the binary particles varies with rotational speed direction of the adjacent axial segments, but not with the drum length to diameter (L / D) ratio and particle filling rate.