The effect of powder properties of filler on the flowability for molding compound of thermosetting plastic was investigated. The size distribution of filler was varied with classifiers. The compressive property and tapping property of fillers were measured by a compressive strength tester and a powder property tester. The flowability of filler in the form of slit flow and spiral flow was compared. Experimental results showed that 1) the powder packing characteristics such as the compressive property or tapping property affect the flowability when the particle size is considerably smaller than the channel thickness of a die, 2) the particle size distribution, especially the volume fraction of coarse particles, directly affects the flowability of filler when the particle size is close to the channel thickness.

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Impacts of solid particles on a metal target may bring particle electrification. We investigated the impact electrification with particular attention to the effects of environment and metal surface conditions such as elements, hardness and roughness. Electrification in nitrogen atmosphere showed better reproducibility than in wet air atmosphere, and the time course of the electrification was clearly obtained. Our previous electrification model was applied to explain the decrease in electrical charge with elapsed time accounting for the material transfer and the work hardening of metal target. However, only 20% of the decrease could be explained by the previous model. Experiments with several metal targets having different surface roughness revealed that the decrease in charge with elapsed time strongly depends on the surface roughness.

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Gravity separation of plastic, rubber and wire harness in automobile shredder dust is investigated using a gas-solid fluidized bed. Uni-beads (barium silicatitanate glass), zircon sands and glass beads are employed as fluidized particles. Floating and sinking of plastic, rubber and wire harness in the fluidized bed are examined by changing the superficial air velocity. The wire harness is almost completely separated from the other components by using Uni-beads and zircon sands. The plastic can be separated from the rubber by using glass beads, although the separation efficiency is relatively low. Precise adjustment of superficial air velocity is essential to attain high separation efficiency because the particle flow and air bubbles in the fluidized bed affect the floating and sinking of the dust.

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The process of body-feed microfiltration of yeast suspension to which kieselguhr was admixed to reduce the filtration resistance was evaluated using the average porosity and the average specific filtration resistance determined from filtration experiments in which a filter was subjected to a sudden reduction in its filtration area. The dependence of local porosity and effective specific surface area of cake solids on the mixing ratio of filter aids was evaluated by a packing model of binary mixtures. The average porosity and the average specific filtration resistance were calculated from these local values by accounting for the non-homogeneity of the compressible filter cake. On the basis of these values, the filtration rate in body-feed filtration was accurately predicted. The method presented in this paper can be applied for the determination of the optimum dosage of filter aids in body-feed filtration.

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