PURPOSE: To efficiently preheat and reduce a granular raw material without splashing to the outside of the system by combining a suspension preheater, fluidized bed preheating furnace, fluidized bed preliminary reduction furnace and out-of-furnace circulation system to constitute a preheating and reducing device for powdery iron ore.
CONSTITUTION: The powdery iron ore 1 and limestone 2 are preheated by the suspension preheater consisting of a high-temp. exhaust gas flue 24, a piping 25 and a multi-stage cyclone 26 of the fluidized bed preheating furnace 3. The coarse grains directly enter the preheating furnace 3 and the pulverized powder is recovered in the cyclone 26 via a piping 25 by the exhaust gas and flows into the preheating furnace 3. Coal 7 and air 5 from the furnace bottom are blown into the preheating furnace 3 to burn the above-mentioned raw material, by which the raw material is heated and decarbonized. The quicklime formed in such a manner is introduced into the fluidized bed preliminary reduction furnace 6 where the iron ore is preliminarily reduced by the reducing exhaust gas from the melt reduction furnace 10. The pulverized powder is recovered and preliminarily reduced by the outside circulation system 33 including the cyclone 34. The powder is heated by a pulverized coal burner 39 in the final fluidized bed preliminary reduction furnace 6. The coarse grained raw material 41 and pulverized powder raw material 40 are supplied by respective feeders to the melt reduction furnace 10. The iron ore and other raw materials are preliminarily reduced and heated at a good raw material yield and thermal efficiency.
NISHIHARA NOBUYOSHI
EGASHIRA TATSUHIKO
NAKAMURA MASAKAZU
KATAYAMA TSUTOMU
