Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Circulation and Reduction Behavior of Iron Ore in Circulating Fluidized Bed
Masahiko SATOHiroshi ITAYASeiji TAGUCHI
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1992 Volume 78 Issue 7 Pages 1266-1273


The circulation and reduction behavior of iron ores in a circulating fluidized bed prereduction furnace were studied under hot and cold experimental conditions as a part of fundamental study for the development of a smelting reduction process. Three kinds of ore with different particle size and silica sand were used as the circulation materials. The circulation rate of ore was controlled to keep a constant solid hold up in the cold experiments. On the other hand, for the case of hot experiments the circulation rate of ore was not controlled and the solid hold-up was kept constant by supplying a small amount of ore to compensate the dust loss. The results obtained are as follows:
1) The circulation rate of iron ore increased as the particle size decreased and the average solid hold-up in the riser increased. The circulation rate also increased as the gas velocity in the riser increased.
2) The gas velocity and solid hold-up were considered to affect the carrying over of particles as the driving force and the probability, respectively. The ore circulation rate, Gs, was proportional to the product of Fr number and the average solid hold-up (1-ε) in the riser.
3) The rate controlling step in the reduction of very fine ore was considered to be chemical reaction. On the other hand, the reduction of larger ore was affected by both chemical reaction and diffusion in the particles.

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© The Iron and Steel Institute of Japan
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