Segregation of binary mixtures of particles during the filling of a two-dimensional representation of a hopper

Abstract

This paper contains a summary of results obtained from experiments carried out at The Wolfson Centre for Bulk Solids Handling Technology at the University of Greenwich on the segregation of dry binary particle mixtures of the same material when they fill a hopper. A test facility has been built which represents a two-dimensional segment of a hopper. Binary mixtures were fed into this container using amplitude feedback-controlled vibratory feeders via a static in-line mixer and one of two different feed chute designs; one curved and the other straight. 'Thieving' probes were used to sample the segregated heap of material from the hopper. The contents of each probe then underwent size analysis to ascertain the change in the size distribution from that of the original mixture. It is shown that a mechanism, termed embedment, caused by the vertical component of the feed velocity on impact with the forming heap, has a dramatic effect on the segregation process. A detailed discussion of the relationship between the possible mechanisms occurring in the heap formation process in the light of the segregation patterns observed is given.

Novel aspects on the segregation in quasi 2D piles

“…Segregation takes place every time this dry material is handled [2][3][4]. In cement production, raw material is stored as pyramidal heaps and, although empirical homogenization techniques are used with good results, segregation is observed due to the broad distribution of grain sizes.…”

Quality-by-Design (QbD): Effects of Testing Parameters and Formulation Variables on the Segregation Tendency of Pharmaceutical Powder Measured by the ASTM D 6940-04 Segregation Tester

“…On the other hand, for cohesive powders, which do not flow as well, segregation involves overcoming interparticulate bonding forces, for example, van der Waals, electrostatic, and hydrogen bonding. The primary mechanisms of segregation are: percolation (sifting or void filling),2–4 trajectory (rolling),3, 5–8 fluidization,1, 9 push‐away effects,10 angle of repose, and stratification 11–13. A number of papers14–22 have been published previously that examined powder segregation and its effect using different experimental methods.…”

Influence of geometry on stratification and segregation phenomena in bidimensional piles

“…The segregation phenomena always occur when a mixture of grains of different sizes is simply poured onto a heap [1][2][3][4][5][6][7][8][9][10]. Typical segregation leads to the presence of large grains near the bottom of the pile, whereas small ones near the pouring point at the top of it.…”