EFFECT OF MIXING AIDS ON THE TRANSPORT BEHAVIOR OF PARTICULATE SOLIDS

The behavior of particulate materials being transported through rotary drums is strongly affected by the addition of mixing aids to the system. This effect is reflected in three main dependent parameters: holdup, variance of the residence-time distribution, and extent of particulate segregation in the drum. In addition, the discharge rate of material fluctuates widely due to the presence of mixing aids. The holdup decreases to a limiting value with increasing volume of mixing aids. The dimensionless variance of the residence time distribution increases with increasing volume of mixing aids up to a certain limit, beyond which it remained constant. This is the same that controls the constancy of holdup. In a system with segregating components due to differences in such physical properties as density, particle size, particle shape and roughness, the presence of mixing aids virtually eliminates segregation or at least minimizes its effect in all cases. © 1979.