Effect of external factors on segregation of different granular mixtures

D. S. Tan, S. Panda
Advanced Powder Technology
Chute angle, Discrete element method, Fill height, Granular flow, segregation

Segregation is a common problem faced by different pharmaceutical, chemical, and food processing industries due to non-uniformity in the end-products. Our aim is to minimize the segregation of binary granular mixture by changing the external chute-related factors rather than internal factors like material properties which is often not possible in industries. We investigate the effect of inclination angle, friction, fill volume and channel geometry in a steady, gravity driven flow of granular mixture in an inclined plane. We perform the numerical simulation using an open-source Discrete Element Method code – LIGGGHTS. We observe that the segregation of dry granular particles in stream-wise direction of the chute is minimum at low stream-wise velocity i.e. by keeping the chute at a low inclination and adding the wall roughness. The segregation in cross-stream and vertical direction is at a minimum when the chute is filled to at least 40% of its height. We also investigated the optimal conditions for minimum segregation in different granular mixtures and found that a mixture with size or density ratio up to 4 can have minimum segregation, if we fill the chute to 75% height. For a greater size or density ratio, it is difficult to minimize the segregation. The optimal segregation conditions for mixtures with different elastic modulus ratio were generally constant.

Keywords: Segregation, Chute angle, Fill height, Granular flow, Discrete element method

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