(237d) Using Unconventional Baffles to Reduce Segregation within Rotating Drums

Shi, D., SC Johnson and Son Inc.
McCarthy, J. J., University of Pittsburgh

Particle mixing processes are widely used in the chemical, pharmaceutical, food and coal industries. However, achieving good mixing of free-flowing particulate solids with different properties is not a trivial exercise. In particular, particles of different size and density segregate quite strongly in typical tumbler geometries. Industrially, an attempt is often made to augment mixing through the use of baffles which are attached to the wall of a tumbler. We show, through a series of simulations and experiments, that conventional baffle placement has little effect on segregation tendency; however, we further show that through novel placement of baffles one can achieve a dramatic increase in the asymptotic degree of mixedness for typically segregating systems. A simple explanation of this phenomena is put forth and could have a profound effect on future mixer designs.