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 15, Issue 12
Displaying 1-4 of 4 articles from this issue
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  • Segregation of Density-different Particles in a Tumbling Mixer
    Jiro KOGA, Kenji YAMAGUCHI, Ichiro INOUE
    1978 Volume 15 Issue 12 Pages 595-603
    Published: December 10, 1978
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.15.12_595
    JOURNAL FREE ACCESS
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    The mixing of particles with different density is generally accompanied by segregation which prevents the particles from attaining the randomly mixed state. Theory of stady-state Markov chain was applied to describe the vertical segregation of solid particles in a tumbling mixer. The transtion probabilities in the vertical direction were determined by use of a particle-tracing method. Based on these transition probabilities, the concentration profiles, the concentration variances, and the equilibrium states of the density-different particles were simulated with the aid of a digital computer. The calculated results were in good agreement with the exprimental ones.
    It was found that for the same size particles, the heavier particles concentrated in the central zone of the mixture, while the lighter ones segregated neighborhood of the surface layer, and the bottom of the mixture.
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  • Grindability-Index given as a Function of the Specific Surface
    Yoichi ISHIKAWA, Yasushi IIJIMA, Kyuhei OHMURA
    1978 Volume 15 Issue 12 Pages 704-710
    Published: December 10, 1978
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.15.12_704
    JOURNAL FREE ACCESS
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    In the cace of the batch grinding system utilizing the laboratory ball mill, it is necessary to distinguish between the inherent grinding-resistance of the sample itself and the grindability-obstructing effects of the reagglomeration of fine-particies. The grindability of the sample continuously change in accordance with the progress of grinding, because the contribution-rates of grindability-obstructing effect enlarge with the increase of the specific surface area.
    Therefore, the indicating index for the degree of the grindability, that is Grindability-Index, should be considered as a function of the specific surface area.
    We could have developed the equation for Grindability-Index given as a function of the specific surface area. We could have characterized that the constant “a” is the indicating index for the coarsegrindability and the constant “b” is the indicating index for the fine-grindability.
    Gi=KL(a·eb·S-1)
    Gi: Grindability-Index (kWh/t)
    S: Specific surface area (m2/g)
    a: Coarse-grindability constant
    b: Fine-grindability constant
    KL: Linearizing constant
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  • Void Fraction Distribution of Packed Beds
    Cylindrical Beds
    Takamichi YAHIRO, Nobuo HAYANO, Tomosada JOTAKI
    1978 Volume 15 Issue 12 Pages 711-718
    Published: December 10, 1978
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.15.12_711
    JOURNAL FREE ACCESS
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    This work was undertaken because previous data on a radial void fraction had suggested that the void fraction across the diameter of packed beds might be flat distribution at the region without the effects of container wall.
    The present results obtained from comparatively large scale packed beds (container dia. 150mm, particle dia. 0.125mm) showed non-flat distribution at about 80 to 300 particle diameters from the container wall. The distribution function might be explained from vertical pressure distribution.
    The semi-empirical fomula is given finally by Eq. (15).
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  • [title in Japanese]
    Keith Masters, Hidero Aoki
    1978 Volume 15 Issue 12 Pages 719-725
    Published: December 10, 1978
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.15.12_719
    JOURNAL FREE ACCESS
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