PURPOSE: To improve the reduction efficiency and also to stabilize the condition in a fluidized bed reduction furnace by adjusting gas flowing velocity and circulating flow rate of powdery iron in the fluidized bed and keeping grain vol. fraction ratio in the furnace to a specific value at the time of pre-reducing the powdery iron ore in the fluidized bed reduction furnace.
CONSTITUTION: When producing a molten iron from powdery iron ore, with the combination of a pre-reduction furnace and a smelting reduction furnace and without using a blast furnace, a fluidized bed reduction furnace is used as the pre-reduction furnace. The powdery iron ore 4 is charged from lower inlet 3 of an uptake cylinder 1 in the fluidized bed reduction furnace 10, and reducing gas 5 is blown from the bottom part to form the fluidized bed of powder iron ore, and the powdery iron ore is pre- reduced in the solid phase and the ore accompanied with the gas 5 by a cyclone 6 is descended in the downtake tube 2, and the reduced ore is again ascended in the uptake cylinder 1 after taking out a part of the reduced ore from an outlet 7 to form the fluidized bed, and unreducing iron ore is pre-reduced. In this case, by keeping the grain vol. fraction in the furnace within a range of 4-15% in the shown equatation, the reduction efficiency in the fluidized bed reduction furnace is improved.
HAYASHI YOICHI
SUZUKI SATORU
EGASHIRA TATSUHIKO
Next Patent: METHOD FOR OPERATING CIRCULATING FLUIDIZED REDUCTION FURNACE OF POWDERY ORE AND REDUCTION FURNACE