Journal of the Society of Powder Technology, Japan
Online ISSN : 1883-7239
Print ISSN : 0386-6157
ISSN-L : 0386-6157
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Volume 30, Issue 4
Displaying 1-5 of 5 articles from this issue
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  • Estimation of the Mixing Index Based on the Contact Number between Different Particles by Spot Sampling
    Hisakazu SHINDO
    1993 Volume 30 Issue 4 Pages 234-239
    Published: April 10, 1993
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.30.4_234
    JOURNAL FREE ACCESS
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    The contact number between different particles, C, was previously proposed in contrast to the traditional one proposed by Akao et. al. The former had better properties than the latter in view of sampling efficiency and an evaluation of a mixture.
    This paper reports on the estimation of C by spot sampling from which the mixing index can be also estimated. The precision of the estimation can be theoretically derived. Comparisons of the estimation precision of C with that of Lacey indicate that the mixing index based on C is superior to Lacey's variance-based mixing index.
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  • Estimating the Cut Size of Needle-shaped Particles During Sieving
    Ryoji UTSUMI, Masami ICHIKAWA, Tetsuo YAMAMOTO, Takayoshi HATA, Kenich ...
    1993 Volume 30 Issue 4 Pages 240-246
    Published: April 10, 1993
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.30.4_240
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    The cut size of the length of needle-shaped particles during sieving by a plain woven wire cloth was investigated. The cut size was theoretically estimated on the basis of the geometrical relationship between the particle and wires making up the sieve aperture. Three critical cases for particle passing were shown, and the critical particle length was derived for each case. Five kinds of enamel wire having different lengths were used as a model of needle-shaped particles, and the particles were sieved by a horizontal impulse acting on the sieve. The sieving rate increased with decline in the particle length. It was found that a critical length at which the sieving rate extremely decreased existed, and the length could be estimated by the critical models.
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  • The Existence and Characteristics of Two States of Thermal Stability Limits in Autoxidative Self-heating Powder Beds
    Yoji NAKAJIMA, Satoru FURUSAWA, Hua LIANG, Tatsuo TANAKA
    1993 Volume 30 Issue 4 Pages 247-254
    Published: April 10, 1993
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.30.4_247
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    Two opposing effects of aeration are expected; one improves the thermal stability by air flow cooling, and the other enhances autoxidative heating by the promoted reaction rate with fresh air. The latter is hazardous for powder beds in which the autoxidation is suffocated by the resistance of oxygen diffusion through the bed.
    According to a model calculation, the thermal stability limits of autoxidative powder beds are classified into two types, i. e., the oxygen deficit type and the F-K (Frank-Kamenetskii) type. In the first type, the temperature rise is quite high, and the oxygen concentration becomes low, but the thermal stability is fairly robust against the deterioration of ambient conditions. The F-K type exhibits a sharp contrast to the above type. The stability of the F-K type is critical and apt to result in a thermal catastrophe. Aeration will improve the thermal stability of the F-K type.
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  • An Experimental Study of the Mechanism of Vertical Conveyance of a Bulk Solid in a Pipe Belt Conveyor System
    Hiroshi TSUNAKAWA
    1993 Volume 30 Issue 4 Pages 255-260
    Published: April 10, 1993
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.30.4_255
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    This study was done to study the vertical conveying of a bulk solid in a pipe belt conveyor system. An elastic and clear pipe with an inner diameter of 10mm was used as a conveyor belt. The pipe loaded with solid particles was run through guide rollers from horizontal to vertical forming a right-angled bend with a curvature radius of 100mm. The motion of solid particles at the bend was observed by a video camera.
    A steady state of the motion showed that solid particles were slided up by a friction against walls of the pipe and then down onto following particles which arrived at a lower part of the bend. During this motion, particles filled the cross section of the pipe above the bend. From this fact, it was concluded that vertical conveyance could be achieved in the pipe belt conveyor system.
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  • Starch-Based Biodegradable Plastics
    Kenichi KUDO
    1993 Volume 30 Issue 4 Pages 261-267
    Published: April 10, 1993
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.30.4_261
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