Journal of the Society of Powder Technology, Japan

New Methods for Detecting Phenomena in a Silo

Yotaro HATAMURA, Takatsugu TAKEUCHI, Masayuki NAKAO

1997 Volume 34 Issue 5 Pages 312-323
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.312

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To clarify the stress situation in a silo, many kinds of sensors were developed specifically for: (1) pressure cell, (2) 2-axis stress cells, (3) slipping velocity detectors, (4) surface temperature detectors, (5) internal temperature and slipping velocity detectors.
The detecting parts of pressure cell and 2-axis stress cell are composed of a “parallel plate structure” and strain gages which can detect pressure and pressure/frictional-stress, respectively.
Using the measurement of the physical phenomena in silo, the following things are concluded: pressure cells and 2-axis stress cells (1) are excellent and (2) using the above detectors, the fundamental physical phenomena in a silo can be clarified.

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The Correlation between Size Reduction and the Mechanical Activation of Talc by a Multi-ring Media Mill

Kenji HAMADA, Shin-ichi YAMAMOTO, Mamoru SENNA

1997 Volume 34 Issue 5 Pages 324-329
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.324

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The correlation between size reduction and mechanical activation in the wet grinding of talc was studied using a multi-ring media mill. The intensity of the compressive force exerted by the grinding rings of the mill was controlled by changing the material of the grinding rings, i. e., those made of tungsten carbide alloy (WC), stainless steel (SUS), partially stabilized zirconium oxide (ZrO₂) and polyoxy methylene (POM). Products were characterized by median particle size, D, specific surface area, S, fractional amorphization and 50% dehydration temperature. Both size reduction and agglomeration were observed under high compressive force leading to a stationary state. The apparent rate of fractional amorphization was almost proportional to the increase in the compressive force. The decrease in 50% dehydration temperature changed linearly with the degree of apparent fractional amorphization.

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Evaluation of the Mixing Process Based on a Disintegrating-Rate-Model of the Powder Agglomerates

Munetake SATOH, Tatsumori YOSHIDA, Takeshi YANAGIDA, Tomohiro IWASAKI, ...

1997 Volume 34 Issue 5 Pages 330-336
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.330

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The mixing process of powders in an agitation type of solid mixer was described based on a modified comminution model. The mixing procedure of the fine and adhesive powders was expressed by means of the disintegration process of the tracer agglomerates (iron-oxide) in the bulk powder bed (calcium carbonate) in this model.
The hypothetical breakage region (maximum stress solid volume) which formed around the impeller passing through the powder bed was defined as functions of the scale of the mixer vessel, the number of impeller blades and the rotary speed. Model parameters of the selection function and the breakage distribution function were determined by measuring the change of size and distribution with time for the agglomerates of the tracer.
The effects of the scale of the mixer and several operating conditions on the mixing processes were discussed using the presented model and experimental results.

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The Rapid Dissolution of Trace Amounts of the Iron Formed by Abrasion in Wet Grinding

Tetsuo KATSUYAMA, Keita TAKEKOSHI, Yoshiteru KANDA

1997 Volume 34 Issue 5 Pages 337-342
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.337

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In a grinding process, small amounts of iron are generally formed in the ground products. In the present study, the iron resulting from abrasion in wet grinding could be instantly oxydized by iron (III)-edta complexes (edta: ethylenediaminetetraacetic acid) in the presence of edta and oxygen to form iron (III)-edta. This iron-dissolving reaction was catalyzed by the iron (III)-edta complex, and was carried out more easily as the reaction proceeded. The final iron (III)-edta complexes were water-soluble and extremely stable.
Consequently, the iron resulting from the abrasion can be eliminated completely by washing the ground products with water. In this study, the dissolutions of the iron attributed to the wear of a steel ball were mainly investigated in detail.

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Flow Characteristics of Draft Tube Spouted Bed and Its Application

Yasuo HATATE, Kazuya IJICHI, Yoshimitsu UEMURA

1997 Volume 34 Issue 5 Pages 343-360
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.343

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DuPont and Particle Technology from 1802-1996

Hiroyuki KOHAMA

1997 Volume 34 Issue 5 Pages 367-369
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.367

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[title in Japanese]

Toshio OSHIMA

1997 Volume 34 Issue 5 Pages 370-372
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.370

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[title in Japanese]

Fude CUI

1997 Volume 34 Issue 5 Pages 373-374
Published: May 10, 1997
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.34.373

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