Controlling Cohesive Particle Mixing and Segregation

Abstract

We observe experimentally that particle systems that would otherwise mix can be made to segregate and vice versa simply by adding moisture. Using a newly developed theoretical approach, we generate phase diagrams that exhibit both mixed and segregated phases and show how the location of phase boundaries may be manipulated via modifying the mechanical and surface properties of the particles. These results have implications for industrial mixing/separation processes as well as novel particle production methods (e.g., engineered agglomerates with precisely prescribed compositions).

Sculpting sandcastles grain by grain: Self-assembled sand towers

“…Depending on this saturation, four regimes of liquid content have been identified [11,13,14]: pendular (the grains are held together by liquid bridges and open structures appear), funicular (large liquid clusters and voids filled with air coexist), capillary (all voids are filled with liquid, and the grains are held together by capillary pressure), and slurry (grains fully immersed in liquid). Most of the experiments on the stability of wet piles have been carried out in the pendular regime [4][5][6][8][9][10]15,16]. It is known that the stability of the pile is unaffected by the presence of the fluid in the slurry regime [6].…”

Granular mixing and segregation in zigzag chute flow

“…Samadani and Kudrolli [4] found that segregation could be reduced by adding a small volume fraction of fluid to different sized particles. Similarly, Li and McCarthy [9] found that segregation could be turned on or off by adding a small amount of moisture to mixtures of particles with different sizes, densities, and/or surface characteristics. Jain et al [10], Thomas [11] and Hajra and Khakhar [12] performed experiments for binary mixtures composed of different sized and different density particles and they found that limited success in achieving mixing can be obtained if the denser beads are bigger and also if the ratio of particles size is greater than the ratio of particle density (sometimes requiring extreme ratios).…”

Particle scale investigation of flow and mixing of wet particles in rotating drums

“…The capillary force reduces flowability of particles and causes flow of wet particles to behave significantly differently from dry particles [4] in terms of flow pattern [5], mixing [6] and segregation [7]. Previous studies, however, largely focused on the macroscopic and qualitative descriptions of the flow.…”