FLOW OF BINARY-MIXTURES OF EQUAL-DENSITY GRANULES IN HOPPERS SIZE SEGREGATION, FLOWING DENSITY AND DISCHARGE RATES

Binary mixtures of equal-density granules at different size ratios and weight fraction were allowed to discharge from a funnel-and a mass-flow hopper. Size segregation during incompressible flow of coarse particles was monitored by measuring discharge rates during various flow stages of the batch emptying of the hopper. Static and flowing bulk densities of the mixtures were determined experimentally as a function of both the fines fraction and the size ratio. Experimental results conform closely to the microstructural changes that occur within the particle bed; a transition from a coarse continuous to a fines continuous bed structure is made possible by the addition of more fines or by increasing the size ratio. Theoretical analyses are presented to explain the phase transition of the microstructure and its effects on the observed bulk densities, discharge rates and size segregation. © 1989.