A continuous granulation process for the smaller and more spherical granules is developed by using a single rotating conical vessel in which a simultaneous operation of granulation, grinding and separation might be performed with grinding media.
It is experimentally confirmed by granulating CaCO₃-powder with water that the final granule size (_??_1mm) is affected by the feed ratio of the binder to powder and grinding conditions. The experimental results can be explained by a granulation process model of the simultaneous operation in a continuous rotating conical vessel. The present model is based on the following granulation characteristics: (1) The amount of the larger granules increases with the feed ratio, (2) the larger granules segregate toward the grinding zone near the wider end of the vessel and are selectively ground into smaller granules, the size of which is given by the grinding intensity, and (3) the final product size is given by the amount and size of granules ground in the wider end and rounded in the narrower one of the vessel.
As a result, the final granule size decreases with a larger grinding effect and increases with a smaller grinding effect on the larger granules, as the feed ratio increases.

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A slurry for slip-casting generally shows a rheological change with the elapse of time from the beginning of the preparation. Such a time dependence seems to be strongly influenced by structural changes in the size and shape of the aggregated particles in the slurry. The present investigation was undertaken to suggest a reasonable schematic model for the aggregation process of particles. Moreover, the change of apparent viscosity and the flow rate dependence of spinability were also explained by the suggested model.

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Studies were made on a binary minerals-aqueous solution system using fluorite and calcite. The concentrations of mineral constituent ions in the supernatant were measured. Flotation tests were carried out. A special apparatus and method developed to simulate real flotation in a plural minerals system were used. Zeta potential measurements were performed using a new apparatus designed to measure the zeta potential of individual powder samples in an aqueous solution containing plural samples.
All results obtained in the binary minerals system differed from those in the singular mineral systems. The difference was caused by the effect of the ionic species dissolved from both minerals in the aqueous solution. This was interpreted in terms of the surface precipitation and/or surface reactions between both minerals and the dissolved ionic species. The results of chemical thermodynamic calculations showed that the fluorite phase was more stable than the calcite phase below pH 8.4-9.3, where the calcite surface in the binary minerals system became similar to that of fluorite. Above this pH range, the reverse phenomenon was observed.

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It was worthwhile to discriminate the state of surface modified particles which were produced by passing raw particles through a fluid mill in which a fluid was circulating with high speed and energy.
For this purpose, we measured the values of impedancne Z (electric resistance in alternating current) of the dispersion systems where the modified particles were dispersed in methanol solution.
From experimental values of impedance Z, some information about the method of discrimination was obtained.
The results are summarized as follow:
(1) It was found that the magnitude of impedance Z of each dispersion system changes with the change in the combination of materials (core and wall).
(2) It was possible to discriminate the state of surface of modified particles from the nonmodified particles by observing the relationship between the impedance Z and the concentration of the powder in each dispersion system.
(3) In the PMMA/Nyion 12 system, the impedance Z of each dispersion system was closely related to the amount of PMMA powder.

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