Ringlike spin segregation of binary mixtures in a high-velocity rotating drum.

This study presents molecular dynamics simulations on the segregation of binary mixtures in a high-velocity rotating drum. Depending on the ratio between the particle radius and density, similarities to the Brazil-nut effect and its reverse form are shown in the ringlike spin segregation patterns in radial direction. The smaller and heavier particles accumulated toward the drum wall, whereas the bigger and lighter particles accumulated toward the drum center. The effects of particle radius and density on the segregation states were quantified and the phase diagram of segregation in the ρ(b)/ρ(s) - r(b)/r(s) space was plotted. The observed phenomena can be explained by the combined percolation and the buoyancy effects.