Controlling Segregation by Particle or Process Designs through Fundamental Understanding

Particulate products tend to segregate due to size differences of different components when handled, processed, or transported in a variety of industries ranging from chemical to pharmaceutical to agricultural. Segregation can cause unwanted product quality issues or process upset, resulting in significant financial losses due to the need of remixing these products or off specs products. There are many different mechanisms for particle size segregation including sifting/percolation, angle of repose, bouncing, and fluidization, where the sifting and percolation mechanism is the most prominent driving mechanism for granular materials above 200 microns. This talk presents an approach to control segregation of granular materials by properly designing particles (e.g. size or shape) or process conditions based on a recently developed continuum model [1], where particle properties and process conditions are incorporated. A few examples are presented to show how particle size, size distribution, and shape can be modified or process conditions such as feed flow rates can be regulated to minimize segregation. In a rare case, we also show an example of how the approach can be used to optimize process conditions to utilize segregation to achieve better process efficiency and product quality.

[1], Y. Fan, C. Schlick, P. Umbanhowar, J. Ottino, and Lueptow, “Modelling size segregation of granular materials: the roles of segregation, advection and diffusion”, Journal of Fluid Mechanics 741, 252-279, 2019.