(673e) Segregation of Fragile Granular Materials

Authors: 
Freireich, B., Particulate Solid Research, Inc.
Fan, Y., The Dow Chemical Company
Jacob, K., The Dow Chemical Company
Segregation of granular mixtures of different size particles has wide implications in various industrial processes such as hopper and bin filling and discharge, blending in rotating tumblers, or chute transferring. Segregation in these industrial processes often cause loss of process efficiency or product quality due to particle spatial inhomogeneity. Recently, a continuum approach [1] combining the advection, percolation, and diffusion mechanisms of granular flow has been developed to quantitatively model percolation-driven particle size segregation. This model has demonstrated the ability of accurately predict particle segregation in a range of flow geometries, processing conditions, and particle size distributions. However, the model is limited to non-fragile particles, whereas in many industrial applications, particles such as coals, food stuffs, or agglomerated chemicals and pharmaceuticals can break during processing or transportation, which can result in segregation or impact segregation dynamics. In this research, we develop a theoretical model considering particle attrition in segregating granular flow by incorporating a population balance model of size reduction into the continuum segregation approach. Inclined chute flow is used as a model flow to examine this segregation-attrition model for an initially monodisperse granular material that can break into either a bidisperse granular mixture or a polydisperse granular mixture.

[1] Fan et al. “Modelling size segregation of granular materials: the roles of segregation, advection and diffusion” Journal of Fluid Mechanics, 741, 252-279, 2014.