Two step twin-single fluidized bed pre-reduction apparatus for pre-reducing fine iron ore, and method therefor

Abstract

A two step twin-single fluidized bed type reduction apparatus for fine iron ore, and a method therefor, are disclosed. The fluidizing of the fine iron ore is stabilized so as to improve the reduction degree and the gas utilization rate, and so as to minimize the elutriation loss of the iron ore. The apparatus includes a first fluidized bed furnace for carrying out a first pre-reduction on only coarse/intermediate iron ore particles among fine iron ores of a wide particle size distribution by a bubbling/turbulent fluidization after their charge from a charging hopper, while making fine iron ore particles fly away. A second fluidized bed furnace carries out a first pre-reduction on the fine iron ore particles flown from the first fluidized bed furnace by a bubbling fluidization, and a third fluidized bed furnace carries out a second pre-reduction on the iron ores discharged from the first and second fluidized bed furnaces after their first pre-reduction. A first cyclone captures extremely fine iron ore particles from an off-gas discharged from the second fluidized bed furnace to circulate them back to the second fluidized bed furnace. A second cyclone captures extremely fine iron ore particles from an off-gas discharged from the third fluidized bed furnace to circulate them back to the third fluidized bed furnace. A gas reforming system reforms a part of the off-gas of the first cyclone to circulate the reformed gas to the first and second fluidized bed furnaces.