An experimental investigation into sifting and fluidization segregation characteristics for coal fly ash

Abstract

Sifting and fluidization segregation characteristics were determined for 6 different fly ash samples (particle size ‘d50’ ranging from 68 µm to 141 µm) using standard testers. The results have shown that the coarser particles have a greater tendency to sifting segregation, and the finer powders respond more to fluidization segregation. The angle of repose for the fine ash and coarse ash were 55° and 38°, respectively, which indicated poor to good flowability conditions. The flow function test shows that all the samples were in an easy-flowing to a free-flowing zone. The angle of repose and material flow function have provided a good correlation with the sifting segregation index. In contrast, cohesion between particles, the ratio of free terminal velocities and diameters for coarse to fine particles have shown a good fit with fluidization segregation indices. For both sifting and fluidization segregation, the model correlation values are 0.91 and 0.94, indicating the predicted results are a good fit to the experimental data.