Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1996-10-28
1998-07-28
Kastler, Scott
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75450, 266172, 266156, C21B 1100, C21B 1314
Patent
active
057857334
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluidized-bed-type reduction apparatus for reducing fine iron ores in the procedure of producing pig iron or ingot iron and a method for reducing iron ore particles using such an apparatus, and more particularly to a fluidized bed type reduction apparatus capable of efficiently reducing fine iron ores of wide size ranges in a stably fluidized state and a method for reducing iron fine ores using the apparatus.
2. Description of the Prior Art
Generally, conventional methods for producing pig iron from reduced iron ores include a method using blast furnaces and a method using shaft furnaces. In the latter method, iron ores reduced in a shaft furnace are melted in an electric furnace.
In the case of the method for producing pig iron using blast furnaces, a large amount of coke is used as a heat source and reducing agent. In accordance with this method, iron ores are charged in the form of sintered ores in order to improve the gas-permeability and reduction. To this end, conventional methods using blast furnaces need a coke oven for producing coking coal and equipment for producing sintered ores. For this reason, the method using blast furnaces is a method requiring a huge investment and a high energy consumption. Since high quality coking coal is maldistributed in the world and the amount of its reserves are diminishing, the shortage thereof becomes severe as the demand for steel increases. On the other hand, the method of reducing iron ores using shaft furnaces requires a pretreating step for pelletizing iron ores. Since this method also uses natural gas as a heat source and reducing agent, it has a drawback that it can be commercially implemented only in areas where an easy supply of natural gas is ensured.
Recently, a smelting reduction method capable of producing ingot iron from iron ores using non-coking coal in place of coke has been remarkable as a new iron production method.
Such a smelting reduction method typically employs a system wherein iron ores pre-reduced in a separate furnace are completely reduced in a melting furnace to produce hot metal. In the reduction furnace, iron ores are reduced in a solid phase before they are melted. In other words, iron ores charged in the reduction furnace are reduced while being in contact with hot reducing gas generated in the melting furnace.
The reduction process used in this method is classified into a moving bed type and a fluidized bed type in accordance with the condition that iron ores are in contact with the reducing gas. It has been known that one of the most promising method for the reduction of fine iron ores of wide size distribution is the fluidized bed type process wherein the ores are reduced in a fluidized state by a reducing gas supplied through a distributor which is installed in the lower part of the reactor.
An example of the fluidized-bed-type reduction furnace is disclosed in Japanese Patent Laid-open Publication No. Heisei 3-215621. As shown in FIG. 1, this furnace comprises a cylindrical reduction furnace 91 and a cyclone 95. When iron ores are charged through an inlet 92 and a reducing gas is supplied in the reduction furnace 91 via a line 93 and a distributor 96 at an appropriate flow rate, the iron ores form-a fluidized bed above the distributor so that they can be mixed and agitated with the reducing gas. In this state, the iron ores can be reduced by the reducing gas. The reducing gas supplied in the furnace forms bubbles in a layer of iron ore particles as if a fluid is boiled, and then rises through the particle layer, thereby forming a fluidized bed of iron ore particles. Therefore, this fluidized bed is a bubbling fluidized bed. The reduced iron ores are discharged out of the reduction furnace 91 through an outlet 94.
In the case of the fluidized-bed-type reduction apparatus disclosed in the above publication, it is necessary to minimize the flow rate of the reducing gas while forming an effective fluidized bed so as not only to reduce the e
REFERENCES:
patent: 4434001 (1984-02-01), Edstrom
patent: 5370727 (1994-12-01), Whipp
patent: 5407179 (1995-04-01), Whipp
patent: 5439504 (1995-08-01), Czermak et al.
patent: 5531424 (1996-07-01), Whipp
Hauzenberger Franz
Jung Bong Jin
Kim Hang Goo
Kim Yong Ha
Lee Il Ock
Kastler Scott
Pohang Iron & Steel Co. Ltd.
Research Institute of Industrial Science & Technology
Voest-Alpine Industriean-lagenbau GmbH
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