DISPERSION OF AGGREGATES OF FINE POWDER BY ACCELERATION IN AN AIR STREAM AND ITS APPLICATION TO THE EVALUATION OF ADHESION BETWEEN PARTICLES

Dispersion of aggregate particles by acceleration in an air stream is examined both experimentally and theoretically. In the experiments, se veral kinds of powders composed of particles of around 1 mu m are disp ersed by a high speed air stream at the throat of an ejector type disp erser. The dispersed particles are observed with an optical or electro n microscope. A numerical simulation is made with aggregates of differ ent sized spheres, comparing the dispersion force acting on each aggre gate with the adhesion force between spherical particles. The experime ntal dispersion results obtained for some kinds of powders agree with the simulation results. In the case of a few other kinds of powders, d ispersion of the aggregate particles is actually more difficult than s uggested by the calculations based on the assumption of spherical prim ary particles. Comparison between the experimental results using an ej ector type disperser and the numerical simulation results is useful fo r the evaluation of adhesion between particles.