286021 Understanding and Preventing Complex Segregation Behavior

Thursday, November 1, 2012: 2:46 PM
Conference A (Omni )
Kerry D. Johanson, Material Flow Solutions Inc., Gainesville, FL

Differences in almost any particle scale or bulk property can cause separation of particles.  Industry and academia have focused on attempting to understand these various causes by the study of bimodal mixtures which are designed to facilitate one type of separation over the other.  The basic premise is that if one can separate the cause and fully describe the behavior, then one can extend that understanding to more complex situations (i.e. multiple components or complex geometries).   While this is instructive and is an accepted engineering approach to understanding behavior, it fails with real world mixtures where blends consist of three to six unique ingredients.  Complex interactions occur when more than two materials are present in a mixture and simple bimodal segregation behavior is often not additive.  Thus, one cannot successfully describe the overall separation behavior as a linear combination or superposition of two simple component interactions.  Particle or component separation can occur within a subset of ingredients because of their unique interactions.    This paper will discuss multi-component segregation data collected on mixtures with three or more ingredients.  This data will be compared with advancements in modeling segregation using a convective-dispersion approach that is driven by mechanistic fluxes.  This approach will highlight and explain why a symbiotic segregation relationship may occur with a set of ingredients, and why some ingredients seem to enhance the segregation potential of other ingredients.   This paper will present data and theory which describe the interaction of sifting, angle of repose, and air entrainment segregation mechanisms and the role cohesion plays with each.  In some cases the addition of cohesion reduces the segregation potential.  This is usually in cases where segregation is dominated by one segregation mechanism.  However, in other systems, segregation increases when cohesion is added due to a change in mechanism and complex interactions with multiple components.  The theory will show how to model such complex systems to predict segregation potential.  It will also provide a systematic methodology to design products to mitigate segregation from a product point of view.  This approach will provide a basis to help formulators design a particle system to mitigate or reduce segregation tendencies.

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See more of this Session: Mixing and Segregation of Particulates
See more of this Group/Topical: Particle Technology Forum