Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1996-10-28
1998-06-09
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
266172, C21B 1314, C22B 514
Patent
active
057626812
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 fine iron ores 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 fine iron 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 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 pre-treating 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 two types, a moving bed type and a fluidized bed type, depending on the condition how iron ores are in contact with the reducing gas. It has been known that one of the most promising methods for the reduction of fine ore 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 reaction furnace.
An example of the fluidized-bed-type reduction furnace is disclosed in Japanese Utility Model Application Laid-open No. Hei-1-114653, and its construction is illustrated in FIG. 1. As shown in FIG. 1, this furnace includes a cylindrical furnace body 1 in which fine iron ores are reduced. The cylindrical furnace body 1 is provided with an ore inlet 2, a reducing gas inlet 3, an reduced ore outlet 4, and an exhaust gas outlet 5.
In this fluidized-bed-type furnace, fine iron ores are first charged into the cylindrical furnace body 1 through the ore inlet 2. When a reducing gas is supplied in the furnace through a gas distributor 6 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, and in this state the iron ores can be reduced by the reducing gas. The reducing gas supplied in the reduction furnace forms bubbles in a layer of iron ores as if a fluid is boiled and then rises through the particle layer, thereby forming a bubbling fluidized bed. The reduced iron ores are discharged from the furnace through the ore outlet 4 and then fed to a melter gasif
REFERENCES:
patent: 4434001 (1984-02-01), Edstrom
patent: 5082251 (1992-01-01), Whipp
patent: 5370727 (1994-12-01), Whipp
patent: 5554206 (1996-09-01), Czermak et al.
Chung Uoo Chang
Jung Bong Jin
Kepplinger Werner L.
Kim Hang Goo
Kim Yong Ha
Andrews Melvyn
Pohang Iron & Steel Co. Ltd.
Research Institute of Industrial Science & Technology
Voest-Alpine Industriean-lagenbau GmbH
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