Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Study on Classification Accuracy of Pneumatic Sieve
Jun-ichi KOKADONatsuo HATTAKnici NAKAYASU
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1970 Volume 56 Issue 6 Pages 683-694

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Abstract

The classification method by pneumatic sieve has been developed to eliminate fines in ores charged into blast furnaces. When particles are supplied into air stream upward, smaller particles float up and larger one sink down. In this method, the apparent specific weight, the drag ccefficient of the particles, and the interference of moving particles in the air stream (especially between floating-up and sinking-down particles) affect the classification accuracy.
In this paper, the above effects are experimentally and theoretically discussed. Conclus: ons are as follows;
(1) The classification by pneumatic sieve is available with the difference of floating velocity of particles, even if apparent specific weight and drag coefficient scatter in some extent.
(2) The scattering of apparent specific weight and drag coefficient affects the classification accuracy significantly for the particles of diameter nearly equal to the floating particle diameter Ds and negligibly for the particles of diameter less than half of Ds.
(3) For the classification of particles in the same particle size distribution, the weight ratio in each size range of floating-up particles to supplied one decreases logarithmically with increasing mixing ratio M.

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© The Iron and Steel Institute of Japan
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