Dependence of flowability of dusts from dry off-gas de-dusting and other fine granular powders on the consolidation stress

The ratio ffc of the consolidation stress 1 to the unconfined yield strength c provides a quantitative characterization of the flowability of fine-grained solid powders (Schulze 1996). The larger the ffc is, the better a powder flows. The flowability of a fine-grained solid depends on the consolidation stress. Usually, better flowability is observed at higher values of the consolidation stress (Schulze, 2008, p. 42). A good visualization of this dependence is obtained in a diagram showing the unconfined yield strength, dependent upon the consolidation stress that also includes lines of constant flowability. The effect of improved flowability at higher values of the consolidation stress has been observed for many dusts from dry off-gas de-dusting (Lanzerstorfer, 2016a,b). However, in some cases the flowability does not improve at higher consolidation stress. In this study the correlation of the consolidation stress dependence of the flowability with various bulk powder parameters (mass median diameter, bulk density, angle of repose) was investigated.