Clogging reduction by addition of small particles of various material densities

We present an experimental investigation on the flow and clogging of bi-disperse mixtures of coarse and fine grains of different densities passing through small orifices. We vary the density ratio (coarse/fine) from 1.87 down to 0.79 by using amaranth seeds, glass and ceramic beads of similar size as the fine species in combination with 2.0 mm glass beads as the coarse grains. We analyzed the effect of the density ratio on the effective flow rate of the coarse species, the segregation during flow and the clogging for a range of orifice diameters. As in previous studies, the flow of the coarse grains is facilitated by the fine species, which prevents clogging. We show that the effective flow rate of the coarse species is virtually independent of the density ratio. These results suggest that in practical applications with the goal of clogging reduction, the density of the fine species used to ease the flow is not a relevant parameter and can be selected based on practical or economic constraints.

Graphic abstract

Schematic diagram of the flow of large grains through a small orifice when they are diluted in a mixture with fine grains