Controlling Particle Segregation: To Mix or Not To Mix?
Location:138 DeBartolo Hall
Did you ever notice that the first bowl of raisin bran has no raisins and the last one is almost *all* raisins? This is a minor annoyance at breakfast, but can be life-threatening if the same thing happens when manufacturing your heart medication. Segregation, or un-mixing, of particles can be a costly problem and a source of frustration for industries ranging from pharmaceuticals to ceramics to agriculture. When particles differ in almost any mechanical property—size, density, shape, etc.—they become very difficult to keep homogeneous and this problem can even plague "uniform" materials if their is a size or shape distribution within the sample. While the majority of early studies of segregation focused on identifying mechanisms and kinetics of segregation processes, this foundational work has allowed a number of recent studies to aim at minimizing the extent of segregation in several industrially-relevant model systems. In this talk, we highlight recent advances in controlling segregation. Specifically, we examine two techniques for segregation control. The first involves using interparticle cohesion, both due to van der Waals forces and/or liquid bridges, either to cause or prevent segregation. The second technique, inspired by fluid mixing, allows us to exploit flow perturbations to limit or even eliminate segregation in free-flowing systems. Time permitting, we will close with a discussion of how similar techniques may be used to devise "green" particle separation techniques.
University of Pittsburgh
Professor McCarthy is a graduate of Notre Dame (class of '93) and Northwestern University. Joe has been at Pitt for 15 years and is currently the Vice Chair for Education and a WKW Professor of ChE in the Swanson School of Engineering. He uses computational modeling to study the flow, mixing, and segregation of particles for pharmaceutical and materials processing applications.