Stability Angles in granular raw matter related to cement production

VIDALES, A M; IPPOLITO, I.; BENEGAS, O.A.; AGUIRRE, F.; NOCERA, O.C.; BAUDINO, M.R.

Viña del Mar, Chile

Workshop; Southern Workshop on Granular Materials 2006; 2006

CIMAT

Raw granular materials used in cement manufacturing are limestone grains displayinga broad size distribution, ranging from microns to a couple of inches. They are storedas pyramidal heaps and, although empirical homogenization techniques are used with goodresults, there are important factors like segregation and grinding conditions that produce ixtures with different poorly controlled size. For this reason, the stability of the heapsstrongly depends on these factors and it is important to study the influence of therespective amounts of particles of different sizes on the properties of the mixture.In this work, we report experiments analyzing the relationship between the characteristicangles of equilibrium of the heaps and the geometry, size and chemical composition of thegrains. We also look for correlations between the values of the characteristic anglesand the relative amounts of grains of different sizes that make up the materials.We demonstrate that the chemical composition is correlated with the geometry of thegrains and that their aspect ratio does not influence the critical angles. We also showthat the critical angles mostly depend on the relative amount of fine grains in thegranular mixture and on the dispersion of the sizes. The results obtained allow one todraw conclusions that may be relevant to the treatment and storage of raw materialsin the cement industry.