Journal of the Society of Powder Technology, Japan

A Study on Granulation by the Fluidized Bed Granulating Method (3)

The Comparison of the Granulating Mechanism and Granule Properties of the Conventional Method with those of the New Method

Yoshihisa SAGAWA, Teruo SAKAMOTO

1984 Volume 21 Issue 7 Pages 393-398
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.393

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In the previous paper, we clarified the defects which the conventional methods of a fluidized bed granulation possessed and found the conditions to reduce these defects. In this paper, we compared the growth of a particle and the mechanism of compactness and smoothness in the conventional method with those of new method and found the conditions to improve the compactness and smoothness of granules in both methods. This accounted for the difference in these methods.
In conventional methods, the compactness and smoothness of granules occurred remarkably in the region of above 300-400μm particle size on regard to the relationship between granulating time and the growth of the particle. They slowly occurred in the region of under 300-400μm in particle size. It was guessed that this was because the plastic deformation of granules was proceeded by contact with the particle-die wall and particle-particle when the gravity of granules exceeded a limit.
On the other hand, in new method the compactness and smoothness of granules occurred as soon as the agitating started regardless of the feed rate of spraying solution. It was supposed that the compactness and smoothness were attained regardless of granule size as the plastic deformation of granules the compulsively occurred by means of mechanical agitating in new method.

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On the Principle of Similarity in the Mechanics of Granular Materials

1 st Report: Theoretical Foundation

Takaaki NAGAO

1984 Volume 21 Issue 7 Pages 398-405
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.398

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The principle of similarity in the mechanics of granular materials is investigated. The fundamental equations including the equations of stress and moment equilibrium, the equation of continuity, the geometrical relation, the stress-strain relations and the boundary conditions are taken into consideration, and six dimensionless numbers are obtained.
The following are deduced from them:
(1) Stress in a granular system in a storage vessel such as a silo is proportional to the height of storage vessel.
(2) The total discharge time is proportional to the square root of the height of the storage vessel.
(3) The flow-out velocity from the discharge gate is proportional to the square root of the gate diameter.
(4) The volumetric flow-out velocity is proportional to the 2.5 th power of the gate diameter.

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On the Principle of Similarity in the Mechanics of Granular Materials

2nd Report; Its Confirmation by an Experiment of a Small and a Medium Scale Model of a Silo

Takatsugu TAKEUCHI, Takaaki NAGAO, Yotaro HATAMURA, Nobuyuki NAKAJIMA

1984 Volume 21 Issue 7 Pages 406-418
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.406

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On the basis of the theoretical consideration of the principle of similarity in the mechanics of granular materials, a series of tests has been carried out by using a small and medium scale model of a silo. The pressure and frictional stress distributions on the wall were measured with the biaxial wall stress cells especially developed for this experiment when the granular materials were put in and drawn out of them. Silica sand and wheat were used. The following have been confirmed:
(1) The static wall stresses show values slightly greater than those calculated from Janssen's formula.
(2) In the drawing-out time, the pressure showed values 1.1 to 1.95 times larger than the static ones for silica sand, and 1.0 to 4.03 times larger than those for wheat, while the frictional stress showed values 1.08 to 8.09 times larger than the static ones for silica sand, and 1.0 to 10.35 times larger than those for wheat.
(3) The stress is proportional to the height of the silo, and the volumetric flow-out rate is proportional to the 2.5 to 3 rd power of the gate diameter of the hopper.

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Relationship among Size Distribution of Finished Product, Closed-Circuit and Air-Swept Discharge Systems

Tatsuo TANAKA

1984 Volume 21 Issue 7 Pages 419-421
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.419

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Mixing Characteristics of a Large Type of V-Shaped Tumbling Mixer

Tetsuo AKIYAMA, Isao TADA, Hiroshi KAWAKAMI

1984 Volume 21 Issue 7 Pages 422-427
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.422

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Plasma Activation Treatment of Powder by “PLACTIVELINE”

Toshiyuki SAITO, Kinnosuke WATANABE, Masumi KOISHI

1984 Volume 21 Issue 7 Pages 427-431
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.427

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[title in Japanese]

Kazutaka MAKINO, Masaharu YAMADA, Masayoshi KAWAHARA, Kohtaro KURAMITS ...

1984 Volume 21 Issue 7 Pages 432-434
Published: July 10, 1984
Released on J-STAGE: April 30, 2010

DOIhttps://doi.org/10.4164/sptj.21.432

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