Characterization of segregation in rectangular piles

J. G. BENITO; I. IPPOLITO; A. M. VIDALES

Viña del Mar, Chile

Workshop; Southern Workshop on Granular Materials SWGM09; 2009

Center for advanced Interdisciplinary Reserch in Materials - Universidad de Chile

In recent years, many industries seek to improve quality through a better use of the raw materials and an optimization of the processing plants. In cement production, raw material is stored as pyramidal heaps and, although empirical homogeneization techniques are used with good results, segregation takes place every time this dry material is handled. The aim of this work is to present  the experimental results of granular segregation on rectangular grain piles built up by a moving injection device. In order to understand segregation mechanisms, our experimental set-up allows us to control the following variables: height of the injection point above the top, amplitude and velocity of its displacement and injection flow rate for each kind of grains. Glass beads of different diameters are used in the experiment. Preliminary experimental results demonstrate that the distance of the injection point from the top of the pile and the amplitude of the motion have the largest influence on the segregation. For certain conditions, we observed bands that may be due to the combined effect: grain bearings and the outbreak of small avalanches. If the injection is placed far from the top of the pile, the grains arrive at the pile with greater kinetic energy reducing the segregation. The displacement of the injection point also reduces the segregation phenomenon. A possible explanation is that the horizontal movement allows the percolation of grains in different layers while rolling.