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Volume 30, Issue 9
Displaying 1-9 of 9 articles from this issue
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Fumio SAITO1993 Volume 30 Issue 9 Pages 613
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (1968K) -
Takashi OGIHARA, Teruaki YANAGAWA, Nobuo OGATA, Koukichi YOSHIDA, Yosh ...1993 Volume 30 Issue 9 Pages 614-619
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSMullite fine powders were prepared from the water solution of aluminum nitrate and ethyl silicate hydrolyzed with an HNO3 catalyst by spray decomposition using an ultrasonic atomizer. 0.05-0.1mol/dm3 of HNO3 concentration was necessary to obtain the stoichiometric mullite powders. As-prepared particles were porous, spherical and were of a sub-micrometer size with narrow size distribution. The average particle size increased with increasing concentration of the starting solution and carrier gas flow rate. On the other hand, the average particle size decreased with increasing decomposition temperature. The size distribution and morphology of the particles did not change with the experimental factors, such as concentration of starting solution, carrier gas flow rate and decomposition temperature. The Al2O3/SiO2 ratio of as-prepared powders determined by fluorescence X-ray analysis was about 3:2. Powder X-ray diffraction showed that as-prepared powders were amorphous and crystallized to mullite at 1000°C. The spherical morphology was also retained after the crystallization.View full abstractDownload PDF (3742K) -
Kenichi YAMAMOTO, Tetsuya OKUMURA, Masunori SUGIMOTO1993 Volume 30 Issue 9 Pages 620-626
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSA shape separator (a vibrating rotating disk) was developed, and its performance was investigated for irregularly-shaped particles of 50-300μm in size under various operating conditions. From the shape analysis of sorted particles, shape separation was examined and found to be effective even for 50μm-sized particles. By considering factors that obstruct the rolling motion of particles, it was confirmed that higher separation efficiency might be obtained for lower particle adhesion to the disk, lower surface roughness of the disk, and lower sliding or excessive bouncing of particles on the disk.View full abstractDownload PDF (864K) -
Akira SHIMIZU, Yu-Jun HAO1993 Volume 30 Issue 9 Pages 627-634
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn order to estimate the interparticle reaction rate, an examination of kinetic models was undertaken for three typical uni-directional diffusion systems, Fe2O3-V2O5, Al2O3-CuO and Al2O3-ZnO. Hao-Tanaka's concentric spherical model is found to be valid for these systems based on the difference in the dependence of the reaction rate upon the particle radius, the radius ratio and the molar ratio in the samples. This can be regarded as a generalized model which enables us to the evaluate interparticle reaction rate.
In conventional spherical shell models, the Ginstling-Brounshtein's model is sound in material balance, but with it we are unable to assess the interparticle reaction rate, since the contact points between the particles are not taken into account. Jander's model is most commonly used to represent the reaction rate, however it cannot be used to estimate the value due to serious irrationality in the material balance.View full abstractDownload PDF (852K) -
Changes in the Characteristics of Cation AdsorptionEiki KASAI, Hitoshi MIMURA, Kazumasa SUGIYAMA, Fumio SAITO, Kenichi AK ...1993 Volume 30 Issue 9 Pages 635-640
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSThe effect of dry grinding on the adsorption characteristics, e. g., distribution coefficient and saturated amount of adsorbed cations, of synthetic mordenite has been studied using a radioisotope of 137Cs+ as a tracer. The grinding operation for different periods of time, i. e., 15 to 360min, was carried out using a planetary ball mill.
The grinding operation had no effect on the distribution coefficient onto the mordenite sample at the relatively lower concentration of Cs+ in the neutral and alkaline solutions, though the coefficient significantly decreased in the acidic solutions with an increase in grinding time. The saturated amount of Cs+ adsorbed on the mordenite sample in both neutral and acidic solutions decreased markedly during the early stage of grinding. However, for more than 30 minutes of grinding, the amount of absorbed Cs+ in the neutral solution increased slightly, while in the acidic solution it gradually decreased with grinding time. These observations may be interpreted from the formation of the hydroxyl group on the fractured surface, as well as from the considerable distortion of the channel structure of mordenite induced by grinding.View full abstractDownload PDF (771K) -
The Relationship between the Crystallinity of Raw Materials and Slurry PropertiesTatsuya UEDA, Iwao TADA, Hiroshi KITAMURA, Shinichi OMOTE, Masahiko NA ...1993 Volume 30 Issue 9 Pages 641-645
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSMaking and examination of the rheological property of a slurry for different qualities of pottery stones based on the freeze-dry structure and the quantity of absorbed ions from raw materials and surface charge (ζ-potential) of the particles, it has become clear that there is a remarkable difference that depends on a fine distinction between the constructed minerals in the raw materials.
At present, it seems that these causes come from the absorbed ion K+ which has a close relationship to the quantity of charge, the aggregation of particles and the dispersed structure. Based on this, the practical use of Lowgrade materials can be expected from the industrial point of view.View full abstractDownload PDF (3399K) -
Toshio OSHIMA, Hisato EITOKU, Mitsuaki HIROTA, Michitaka SUZUKI1993 Volume 30 Issue 9 Pages 646-651
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSThe constant feeding performance of a Mohno pump for several kinds of dry powder was examined. The suction pressure of the operating Mohno pump was measured to estimate the feeding mechanism. The results show that the feeding performance depends on the suction pressure and the mechanical strength of the powder arch that was formed at the inlet of the pump. As a result, the powder with the weaker arch strength and the higher pressure drop across the arch is easily sucked into the pump. Then, the feeding performance of the Mohno pump can be estimated from the permeability of air across the powder bed and the unconfined yield strength of the powder bed that indicate the mechanical strength of the arch.View full abstractDownload PDF (774K) -
In the Raw Material of Fine CeramicsOsamu HAYAKAWA, Kenji NAKAHIRA, Jun Ichiro TSUBAKI1993 Volume 30 Issue 9 Pages 652-659
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSIn the field of ceramics, the particle size distribution of submicron powders has been measured by using many kinds of equipment which are based on the different measuring principles. However, at present, laser diffraction and scattering method is the most popular method in particle size analysis. Though this method is good for operation, the refractive index of a particle is necessary to calculate the size distribution. If the refractive index is not considered in the calculation, it will not be possible to obtain proper results. This is the weakest point of the laser diffraction and scattering method for the measurement of an unknown sample.
In this study, a method for the estimation of the optimum refractive index was established by a simple arrangement of the data, and the accuracy of the results was improved.View full abstractDownload PDF (887K) -
Akimitsu SANO1993 Volume 30 Issue 9 Pages 660-662
Published: September 10, 1993
Released on J-STAGE: April 30, 2010
JOURNAL FREE ACCESSDownload PDF (429K)
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