Size segregation mechanism of binary particle mixture in forming a conical pile

The mechanism of particle segregation in forming a conical pile or centrally filling a cylindrical vessel is investigated by applying a Shinohara et al.'s Screening Layer model (1972, 1984 and 1990), where the segregation patterns were measured by a tube-sampling experiment and a DEM simulation. The distribution of mixing ratio of a segregating component of different sizes can be drawn along the pile surface and well correlated with each other for the first time. As a result, the zone, where the segregating component of smaller particle is contained around a central feed point, was found to expand by an increment of the initial mixing ratio, the volumetric feed rate and the flow length of the pile surface. These characteristics are governed by flowability parameters such as velocity ratio, penetration rate and packing rate of the segregating component, which are affected by operating conditions besides particle properties and are to be delved into further. In spite of complicated avalanche phenomena of particles exhibited around the flowing head along the conical pile surface, the present model description consisting of the material balance within the flowing layer was found to be satisfactory in practice with the verifications from the experiments and the microscopic DEM simulation.