The behavior of gravity flow of cylindrical particles and silica sand was investigated using two-dimensional hoppers, of which hopper angles were adjustable. The velocity profiles and trajectories of cylindrical particles were observed, and the flow rates of the both materials were measured. These experimental values were compared with those estimated from our two-dimensional theoretical flow model considering the effect of particle properties such as the angle of wall friction. The following results were obtained : (1) The flow patterns of the both materials were mass flow and also radial flow, (2) The velocity profiles of cylindrical particles depended more clearly on the hopper angle than those expected from a previous theory, and it almost agreed with the calculated values, (3) The normalized discharge flow rate of cylindrical particles was well estimated by the theoretical model. However, the experimental values of silica sand were smaller than the theoretical estimation.

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In chemical engineering processes in which solids are produced, the strength of the substances plays a key role for contact nucleation. In this study, micro-level measurements of the fracture strength of K₂SO₄ crystals were performed under various operating conditions of an MSMPR (mixed suspension and mixed product removal) crystallizer. The degree of attrition and fragmentation behavior was predicted from the fracture strength, the fracture energy, the roundness of the crystal, and the attrition coefficient calculated from micro-hardness properties. The results showed that these properties had different values for each operating condition, and that the minimum and maximum size of the crystal fragmented by attrition could be predicted by means of the attrition coefficient. By evaluating parameters based on micro-hardness, we demonstrated that the stirring speed and the crystal size were the most important of the various operation conditions in the attrition process.

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The influence of solubilization of the solvents for PVB binder on the rheological behavior and properties of alumina green sheets was investigated. Suspensions of alumina particles were prepared with various ratios of toluene (poor solvent) and n-butanol (good solvent) including PVB binder. Binder solutions of concentration 20 wt% were opaque at less than 5 wt% of n-butanol ratio, where turbidities, viscosities, TI values and thread-forming properties of binder solutions were large. These results indicate that the binder molecule exhibits a thread-like shape in poor solvent.
The amount of binder adsorbed on alumina particles in suspension increased with decreasing the ratio of n-butanol, suggesting that binder at the adsorbed state on alumina particles is more stable than at the state of drifting in the poor bulk solvents. And this result suggests that occupation area of thread-like binder is small in poor solvent.
Viscosities, TI values, sedimentation volumes and thread-forming properties of suspensions increased with decreasing the n-butanol ratio. Bulky cohesion structures of alumina particles in suspension with high TI values are supposed to be maintained in sedimentation cakes. However, the packing degree of green sheet after drying was high. The number of binder segments expanding into bulk solution is expected to be fewer, because hydroxyl groups in PVB binder are adsorbed on alumina particles via hydrogen bonding in poor solvent. Expanding binder segment is easy to shrink while drying. Distance between alumina particles decreases, and, as a result, it is thought that the packing degree of alumina particles became high.

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The author has developed an optimized operating system of the pneumatic conveying system using roots blowers to accomplish the energy saving. The system automatically controls the rotational velocity of roots blowers and has an original algorism to prevent the blockage of the duct.
As a result, the power consumption of the new conveying system becomes 50 to 80％ of the original.

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