In order to study an influence of a consolidation stress upon yield loci of powders, a family of reduced yield loci and their corrersponding voidages were measured by a constant volume direct shear tester over a consolidation stress range of 10 to 350gf/cm². The reduced locus was directly drawn in the plane of the shear and normal stresses as the coordinate axes reduced respectively by a factor of corresponding consolidation stress. The Warren Spring equation was also rewritten by the reduced shear and normal stresses. The reduced Warren Spring equation included a shear index, a ratio of a cohesive to a tensile stress and an effective angle of internal friction at steady state failure as parameters. The values of these three parameters were determined from the reduced locus experimentally obtained. In the range of consolidation stress 10 to about 150gf/cm² the three parameters decreased with a decrease in the voidage, but in the range of 150 to 350gf/cm² they did not change without change in the voidage.
A relationship between the unconfined yield stress and the major consolidation stress was found to be superior in an estimation of the flowability of powder to Jenike's failure function which was available only in a limited case when the parameter values were characteristic of the powder.

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For the continuous operation in a multi-stage fluidized bed, it is important to find the region of the operating conditions for stable fluidization and the dynamic characteristics in this region.
In this work, the dynamic characteristics of a simple apparatus, that is, a single-stage fluidized bed is investigated instead of a multi-stage one. The types of a single-stage fluidized bed used are the fluidized bed both without and with a downcomer equipped with an orifice.
The transient responses for the discharging rate of solid particles are examined, when the feed rate of solid particles is changed stepwise. The fluidized particles used is glass beads (D_p=154μm, ρ_s=2.50g/cm³, u_mf=2.2cm/s). The transient responses for the discharge of solids are estimated by developing from the experimental correlations in steady states. The estimated values are agreement with the experimentally measured transients.
It is found that the transient responses in both types of fluidized beds can be shown approximately by the first order lag. The time constant in a fluidized bed with a downcomer equipped with an orifice is recognized to be shorter than that without a downcomer.

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A test mill of rotating disc type was devised to make clear the grinding mechanism in an attrition-and-friction mill. The friction force and the surface roughness of the friction surface were measured, and the production rate and the size distribution of fine particles with respect to load, sliding velocity, and sliding distance were investigated in relation with them. The inorganic matrials such as dolomite earthernware and chalk were used. The experimental variables and ranges were as follows: load; 1.04-23.2N, sliding velocity; 0.22-2.1m/sec.
The following experimental results are obtained:
1) The kinetic friction coefficient μk is increased in a small degree with the increase of applied load, but it is independent of the sliding velocity Furthermore, the fluctuation of friction force has a close relation with the production rate of fine Particles.
2) From the observation of scanning electron micrographs, the fracture surface of brittle fracture is confirmed in the friction surface.
3) The applied load has more significant influence on the average surface roughness of the friction surface than other factors such as sliding velocity and sliding distance.
4) The relationship between the production rate of fine particles Q and the value of PV can be formulated as follows:
Q=k₁(PV)
where the constant k₁ is considered to be an index for easiness of grinding of material, and its value is 0.31mg/J for dolomite earthenware and 0.9mg/J for chalk.
5) The median particle size measured with the electron microscope is about 0.7±0.1μm for dolomite earthenware, and the shape' of particles is an ellipsoid of which the ratio of major radius to minor radius is 1.9.
6) The grinding energy applied to unit volume of produced fine particles and specific fracture-suface energy for dolomite earthenware are estimated to be 2.19±0.39×10³MJ/m³, 200J/m², respectively.

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