Study on Fluidization Mechanism and Agglomerating Behavior of Ultrafine Powders

The fluidization behavior of ultrafine powders SiO_2 and TiO_2 and the effects of powder's properties, packing state and humidity of air on agglomerates' characteristics have been investigated in a bed of 60mm in diameter. It was observed that the fluidizing process of these powders went through three stages: plugging, transiting and agglomerates fluidization with increasing gas velocity, the fluidization behavior of agglomerates was similar to that of larger particles, loose packing of powders was favorable to reduce agglomerates' size, entrainment of powders and improve fluidization quality. Based on these experimental results and analysis of forces acting on powders the fluidization mechanism and agglomerating phenomena of ultrafine powders have been discussed.