The probability density functions of run length between sought particles and its mean in the samples of a random binary mixture are expressed by the geometric and normal distribution, respectively, which were confirmed by simulation. One can thus regard a particle mixture to have the expected proportion of sought particles before mixing when the observed run length or its mean in each sample falls within the 95% confidence limits of the distribution. With regard to the theory, mixing indices using run lengths were investigated to test the statistical randomness of a binary particle mixture.
Experimental results showed that the mean run length decreased as the number of helices increased in the motionless mixer, and 12 helices were needed to obtain a satisfactory random mixture when the number proportions of sought particle are 0.2 and 0.4. However, the run length alone was not suitable as a mixing index because the maximum value in each sample often exceeded the upper confidence limit.

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The Process of the flocculation of suspending particles was carried out by using a two-dimensional model. In this work, agglomerated stearylalcohols were employed as the model particles, and surface active agents such as sodium lauryl sulfate, sodium 1-octanesulfonate and benzalkonium chloride were used as aggregating agents. The contact angles were measured under various concentrations of aggregating agents.
The results obtained were in agreement with Smoluchowski's theory, and the rate constant k varied with the concentration of aggregating agents. These Phenomena may be caused by the orientated adsorption of the molecules of the aggregating agents.

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The sliding friction of a powder due to wall material was investigated. The experiment was carried out for six different sizes of fused alumina powders. As the wall material, an aluminum plate, a steel plate and two kinds of abrasive papers were used.
The pattern of the friction curve was changed by the size of powder and wall material. The friction coefficient was changed by the size of powder and increased remarkably at sizes finer than 10μm. It was also effected by the roughness and hardness of the wall material. Furthermore, it was changed by the sliding velocity of the powder.

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In order to minimize or avoid trouble in spot sampling, it is worthwhile to develop a simple method whereby the degree of mixing or parallelism of packing is non-destructively measured.
In this report, the mixing process of a binary system of particles with different electric resistance, group A and group B, was treated by the use of a two-dimensional simulation.
In order to discuss the change in the total electric resistance of the particle system with the change in the arrangement of the particles in the system, the term “parallelism of packing” defined as inter-row standard deviation was proposed.

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Colloidal silica is usually added to carriers wetted in advance with a small amount of liquid-state agricultural chemicals to improve the flowability in preparing for a solid formation.
Since the relationships between the additive amount of colloidal silica and the flowability and drift characteristics of the formed solid have not yet been studied quantitatively, both relationships are examined in this paper, and the following conclusions are derived:
1. The additive ratio of colloidal silica (called “white carbon, W. C.”) to SiC giving good flowability, increases with the increasing additive ratio of linseed oil to SiC. SiC and linseed oil were used in place of a carrier and liquid-state agricultural chemicals respectively in this study.
2. The bulk density of SiC coated with both linseed oil and W. C. and exhibiting good flowability, decreases with the increase in the additive ratio of W. C. This phenomenon is analyzed by assuming that the thickness of W. C. layers adhering to the surface of SiC with linseed oil increases.
3. It seems that there are two cohesive states of W. C. depending upon the additive ratio. It is difficult to exfoliate the W. C., which adheres strongly to the surface of SiC with the enough linseed oil, from the surface of SiC by an external force. Thus, there is hardly any drift of W. C. into the air. On the other hand, the W. C. attached weakly to SiC is easily exfoliated even by the same external force and drifts into the air. The exfoliation ratio reaches approximately 20% by weight of the total additive amount of W. C. at the minimum additive ratio of W. C. to SiC at which SiC with both linseed oil and W. C. shows good flowability.

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The flow behaviors of a powder bed are significantly influenced by the characteristics of inter-particle friction. The angle of the critical state line from the normal stress axis is equivalent to the angle of dynamic friction of the powder bed. It seems that the angle of dynamic friction of the powder bed is considerably influenced by the shape and diameter of the particle.
In this study, the angle of dynamic friction was measured for 34 kinds of powders having different shapes and/or different diameters. The results showed that the angle of dynamic friction of a powder bed was significantly influenced by the shape of particles and was independent of the diameter of the particles.

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The preparation of ZrC powder from ZrO₂ by reduction with Mg has been investigated from 500° to 1000°C for 2 to 5 molar ratio of Mg/ZrO₂ under a flow of methane. ZrC was formed above 650°C. The reaction finished within 30min above 750°C.
The ZrC powder obtained at 1000°C was ultrafine (below 0.1μm) and had a C/Zr ratio of 0.96. The contents of 0 and Mg in the ZrC powder were 2.9 and 0.4wt%, respectively. The content of free carbon in the ZrC powder became 0.4wt% by decreasing the concentration of CH₄ to 40%. The apparent activation energy for the formation of ZrC was approximately 83.3KJ/mol (750°-900°C).

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A series of experiments was carried out to prepare the ultrafine particle of antimony-doped stannic oxide using a gas-phase chemical reaction. The effect of the reaction conditions, such as the partial pressure of SnCl₄ vapor, the feed-mol ratio of SbCl₅/SnCl₄ and the reaction temperature, was investigated. The identification, mean size, size distribution and shape of particles were studied by X-ray diffraction, T. E. M observation and B. E. T specific surface area measurement. The products were identified as antimony-doped stannic oxide, blue in color, several nm in size (smaller than pure stannic oxide prepared under the same conditions), flakelike in shape. The average size of oxide particles becomes smaller with lower P_MCI, for the range of 0.083-0.1703mol ratio of Sb/Sn and 993-1123K. The lattice constant of Sb-doped SnO₂ particles became larger, and the specific resistance became smaller than that of pure SnO₂.

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In order to examine the confidence in experimental results of the flow properties of a bulk solid, this paper discusses a comparison of the experimental data obtained by using different shear tests methods.
The angle of internal friction of dry granular materials, which has been measured by both the tri-axial shear tester and the fixed volume direct shear tester, increases with a decrease in the voidage of the specimen. Except for the extremely dense and loosely packed states, the experimental results of the angle of internal friction agree within about 3 degrees. For a material in which the particle shape is deflective, there is however a difference of 3 to 5 degrees.
The flowability index for cohesive powders and wet materials is expressed by a ratio of the unconfined yield strength to the bulk density. The experimental results of the flowability index are independent of the two methods of the unconfined yield test and the direct shear test.

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Computer simulation of agglomeration with compaction was carried out using a random addition model, which defined the probability of adhesion of particles at their collision sites as a function of the product of reciprocals of their radii. The agglomeration process simulated by this model was described by a non-random coalescence agglomeration. With as agglomeration proceeded, the outer surface of the agglomerate was compacted more closely than the inside one. It was found that the compaction process of the agglomerate was represented by a modified Kawakita's equation.

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