(477f) Understanding Angle of Repose Segregation – Characterization of a Dual Mechanism

Segregation of powder and granular materials is a current problem with many industrial products. In order to mitigate segregation, one can modify the material or modify the process. Modifying the process allows production of a packaged product that is consistent. However, material in that packaged product can still be prone to segregation during product usage or, in the case of an intermediate product, during subsequent processing. In this case, we have transferred the segregation problem to the end user or to the down-stream processing. The best alternative is to design the material to mitigate segregation under all conditions. This requires that we know the magnitude and mechanism of segregation active with the material. Both the magnitude and mechanism of segregation are dependent on the expected handling and processing at the point of use or during subsequent processing. In either case, measurement of segregation of multi-component mixtures and a mathematical model of segregation are useful when designing product to mitigate segregation. This paper presents a new methodology to measure segregation using spectral techniques and a model to describe angle of repose segregation. A pile forms when material slides down a surface. In this case, friction between particles, as well as the pile slope angle, controls the magnitude of segregation. A pile may also form due when particles rebound off a surface. In this case, the elastic properties of the material and bulk control the magnitude of segregation. This paper presents mathematical models for both these angle of repose segregation mechanisms.