The effects of sieve opening on packing properties of fine powder by tapping under reduced pressure conditions were experimentally investigated. Six adhesive powders forming agglomerates were used as test powders. As a result, the reduction in volume of cement powder by tapping is less with lowering pressure of tapping cell, whereas the opposite effect of pressure was observed for aluminium nitride powder. The reduction in volume of calcium carbonate powder and aluminium nitride powder beds by tapping decreased with the sieve opening because they were highly adhesive so that large agglomerates were formed. Regardless of the difference in tapping conditions for all tested powders, the volume reduction was well correlated to the Hausner ratio.

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Sub-micron particles of fatty acid multivalent metal salt were prepared by a new production process (Jet-Mixing Method). The average particle size of zinc stearate (FC18-Zn) was 0.9μm, calcium stearate (FC18-Ca) and magnesium stearate (FC18-Mg) were 1.1μm and 1.5μm, respectively. These particle size distributions were narrow (maximum particle sizes of FC18-Zn, FC18-Ca and FC18-Mg are 2.1μm, 4.5μm, 6.7μm, respectively). From the results of shape analyses with scanning electron micrograph and image scanning method, the particles of FC18-Zn, FC18-Ca and FC18-Mg were thin in shape, and the particles of FC18-Mg had a high aspect ratio. Particle growth of FC18-Zn in water was accelerated with the rise of temperature, keeping the initial particle shapes.

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In order to predict the dust collection in a moving granular bed with dust generation, a mathematical model accounting for the dust collection coefficient A_d, the dust generation rate S (v), the reentrainment parameters R_d and F_d, is developed. The dust generation rate S (v) is measured without the gas flow for a moving bed of activated carbon at the downward granular moving velocity of 0.35m/h. The collection factor A_d is measured by passing the dust with the concentration of 200-300mg/m³_N through the fixed bed with the void fraction ε at the superficial velocity of 0.35m/s. The reentrainment parameters are determined so as to minimize the difference between the dust penetration predicted by the mathematical model and the experimental one for the moving bed. As a result, the parameters characterizing the dust collection in the moving bed with dust generation are determined as; S (v)=1.99×10-5kg-dust/m³-bed, εA_d=2400h^-1, R_d=0.1, F_d=0.04m^-1.

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