RU2339702C2 - Facility for hot metal manufacturing, directly using small or lump coal and powdered iron ores, method for its production, complete steel mill, using this facility and this manufacturing method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: group of inventions concerns options of method and facility for hot metal manufacturing using small or lump coal and powdered iron ores and holding of high factor of iron-bearing ores reduction during reduction by gas of iron-bearing ores using reducing coal gas produced from coal. Group of inventions also includes complete steel mill using facility for hot metal manufacturing providing receiving of hot-rolled steel sheet, and also its manufacturing method.

EFFECT: creation of facility for hot metal manufacturing with holding of high factor of iron-bearing ores reduction during reduction by gas of iron-bearing ores using reducing coal gas produced from coal.

42 cl, 8 dwg

Description

(a) Scope of the invention

The present invention relates to a plant for the manufacture of molten iron, a method for its manufacture, an integrated steel mill using this plant and method of manufacture, and more particularly, to a plant for the manufacture of molten iron directly using fine or lump coals and pulverized iron ores, to a method for its manufacture, an integrated steel mill using this installation and manufacturing method.

(b) The prior art

Ferrous metallurgy and steel production are the central industry, which supplies the basic materials required in the design and manufacture of cars, ships, household appliances, etc. Moreover, it is an industry that has progressed from the dawn of human history. Metallurgical plants, which play a major role in ferrous metallurgy and the steel industry, produce steel from liquid iron and then supply it to consumers after receiving liquid iron (i.e., pig iron in molten state), using iron ores and coal as raw materials.

Currently, approximately 60% of global iron production is produced using a blast furnace process that has been developed since the 14th century. According to the blast furnace process, coke obtained by using iron ore and bituminous coal as raw materials that have passed through the sintering process is placed in a blast furnace and oxygen is supplied to the furnace to reduce iron ore to iron, thereby producing molten iron. The blast furnace process, which is used to produce the majority of molten iron, requires that the raw materials have a hardness of at least a predetermined level and grain size that can provide ventilation in the furnace, taking into account the reaction characteristics. For this reason, coke, which is obtained by processing special raw coal, is required as a carbon source for use as a fuel and a reducing agent. Also, sintered ore that has gone through a sequential agglomeration process is required as a source of iron. Accordingly, a modern blast furnace process requires equipment for the preliminary processing of raw materials, such as equipment for the manufacture of coke and sintering equipment. Moreover, it is necessary to have accessories in addition to the blast furnace and equipment to prevent and minimize contamination caused by the accessories. Consequently, a significant contribution to additional devices and equipment leads to an increase in the cost of production.

To solve these problems associated with the blast furnace process, significant efforts are being made at metallurgical plants around the world to develop a reduction smelting process that produces molten iron by the direct use of small coals as fuel and a reducing agent, while using directly pulverized ores as an iron source , which account for more than 80% of global ore production.

As an example of such a reduction smelting process, US Pat. No. 5,534,064 describes a method for manufacturing molten iron using pulverized iron ores and lump coals. In this case, the entire installation includes a multi-stage fluidized-bed reactor unit and a gas-filled melting apparatus-gas generator that is connected to the final stage of the multi-stage fluidized-bed reactor unit, so that the source of small iron can be directly used due to the characteristic of the fluidized bed of the fluidized-bed reactor. However, since it is necessary to provide a predetermined space inside the densified layer of the melter-gasifier, the size range of the grain grains of coal that are directly charged into the melter-gasifier is limited. Moreover, the source of fine coal, decreasing in a multi-stage fluidized bed reactor, must be continuously fed into the melter-gas generator. Thus, there is a need for a special loading method. More specifically, since the allowable grain size range of coal, which is used as fuel and a reducing agent, is limited, a significant amount of small coals that are formed during coal mining cannot be used during transportation and storage in the open air. Further, during the operation of the unit with a compacted layer, a significant amount of a source of small iron cannot be used as a source of iron. Moreover, during the operation of the fluidized bed reactor unit, it is necessary to provide an additional installation for the continuous loading of fine reduced iron discharged from the fluidized bed reactor into a gas generator melter.

US Pat. No. 5,961,690 describes a method for manufacturing all products from liquid pig iron or molten steel and an apparatus for implementing this method. Described here is a method and apparatus for manufacturing molten iron by connecting a multi-stage fluidized bed reactor unit and a gas generator smelter, while preventing sticking. Here, part of the flow of reducing gas that flows from the final reactor to the pre-reduction reactor is separated, cooled to room temperature and compressed. Then, the separated reducing gas is again fed to the final reactor, after removal of the CO ₂ contained in the separated reducing gas, in order to increase the amount of reducing gas and thereby reduce iron ore. At this time, the temperature of the gas to be supplied to the final reactor is raised with an additional heater to a predetermined temperature before it is supplied to the final reactor, thereby preserving the temperature inside the final reactor.

Further, as a method of increasing the temperature of the reducing gas at room temperature, a heat exchange circuit is considered in which the temperature is increased by contact with an additionally supplied high-temperature gas, or a self-heating circuit. In the self-heating scheme, part of the room-temperature reducing gas is burned and its calorific value is used to raise the temperature of the reducing gas. However, an additional gas is required in the heat exchange circuit to produce high temperature gas. In the self-heating scheme, the amount of components of the reducing gas, such as CO, H ₂ , etc., available in the reducing gas intended for supply to the final reactor is reduced due to the combustion of part of the gas at room temperature. Moreover, in both schemes, the temperature of the gas at room temperature must be directly increased, so that the thermal efficiency decreases during the time the temperature rises, thereby increasing the energy consumption during the process.

US Pat. No. 5,961,690 also discloses a method of cooling off-gas from a smelter-gas generator to a temperature suitable for supplying it to a final reactor. In this method, a portion of the reducing gas, which is intended for re-supply to the final reactor, is separated before heating and then mixed with the exhaust gas from the smelter-gas generator.

On the other hand, the tar and dust that are formed when the coals are heated and the volatiles are removed from them in the upper part of the melter-gasifier during practical work pass sequentially through the multi-stage fluidized bed reactor unit, along with the reducing gas discharged from the smelter -gas generator. In this case, the resin gradually pyrolyzes in the reducing gas and disappears. Dust is introduced into the stream of pulverized ore passing sequentially through a multi-stage fluidized-bed reactor unit as the reducing gas moves in each of the reactors, and it is circulated again inside the melter-gas generator. Therefore, the amount of dust and resin contained in the reducing gas decreases as they pass through the multi-stage fluidized bed reactor unit.

However, in the apparatus and method described in US Pat. No. 5,961,690, the reducing gas contains a large amount of tar and dust since the reducing gas stream separated from the final reactor passes through only one fluidized bed. Therefore, during the process of cooling the separated reducing gas and removing CO ₂ from it and compressing it, the resin contained in the reducing gas condenses on devices provided as plants for cooling the reducing gas and for removing CO ₂ , which leads to mechanical problems during working hours. Moreover, in the installation and method described in US patent No. 5961690, since there is a need for a cooling installation using water to cool the separated high-temperature reducing gas, in addition to a cooling installation using water, for cooling the gas, which is finally discharged from the multi-stage fluidized bed reactor unit, the amount of cooling water increases, and the load is excessive in relation to the entire process.

Disclosure of invention

The present invention was created to solve the above problems, and the aim of the invention is to provide a plant for the manufacture of molten iron, which uses fine or lump coals and pulverized iron ores and which can perfectly support the rate of reduction of iron ores during gas reduction of iron ores using reducing coal gas, produced from coal, and also the aim of the invention is to provide a method for manufacturing molten iron.

Further, another aim of the invention is to provide a comprehensive steel mill using the above-described installation for the production of molten iron and a method for its manufacture, thereby providing a hot-rolled steel sheet of excellent quality, while at the same time compactly placing all plants and processes.

According to an aspect of the invention, to achieve these goals, a method for manufacturing molten iron is provided, the method comprising the steps of: producing an iron-containing mixture by mixing pulverized iron-containing ores and additional raw materials and drying the resulting mixture; converting the iron-containing mixture into a reduced material by reduction and sintering as this iron-containing mixture passes through a multi-stage fluidized bed reactor unit, the reactors of which are connected in series with each other; briquetting briquetting of reduced material at high temperature; the formation of a layer of compacted coal by loading lump coals and briquettes, which are obtained by briquetting fine coals, into a melting apparatus-gas generator as a heat source for melting briquettes; for manufacturing molten iron by loading briquettes into a gasifier melting apparatus connected to a multi-stage fluidized bed reactor unit, and by supplying oxygen to a gas generator melting apparatus, and supplying reducing coal gas leaving the gas generator melting apparatus to a fluidized bed reactor unit .

Further, a method for manufacturing molten iron may further include the steps of: separating a stream of exhaust gas that is discharged through a multi-stage fluidized bed reactor unit, and removing CO ₂ from the exhaust gas; mixing the converted gas from which the CO ₂ has been removed with reducing coal gas that is discharged from the gas generator smelter and heating the reducing coal gas mixed with the converted exhaust gas before feeding it to the multi-stage fluidized bed reactor unit to adjust the temperature of the reducing coal gas to the temperature required to recover the iron-containing mixture in a multi-stage fluidized bed reactor unit.

The converted exhaust gas can be heated using an oxygen burner in the heating step before feeding the reducing coal gas mixed with the converted exhaust gas to a multi-stage fluidized bed reactor unit.

In the step of separating the off-gas stream that is discharged through the multi-stage fluidized bed reactor unit and removing CO ₂ from the off-gas, the amount of separated off-gas is preferably 60 vol% of the total amount of off-gas which is discharged from the multi-stage fluidized bed reactor unit .

The amount of converted exhaust gas can be maintained in the range from 1050 st.m ³ to 1400 st.m ³ per 1 ton of dusty iron-containing ores.

In the step of mixing the converted exhaust gas from which the CO ₂ has been removed with the reducing coal gas discharged from the gas generator smelter, it is preferred that the amount of CO ₂ contained in the converted exhaust gas is 3.0 vol.% Or less.

The separated off-gas can be compressed at the stage of separating the off-gas stream discharged from the multi-stage fluidized bed reactor unit and removing CO ₂ from the off-gas.

It is preferable to further include the step of separating the effluent gas stream that is discharged through the multi-stage reactor unit of the fluidized bed reactor, and removing the resin from the exhaust gas, before the step of separating the effluent gas stream that is discharged from the multi-stage fluidized bed reactor unit, and removing CO ₂ from the effluent gas.

At the stage of mixing the converted exhaust gas from which CO ₂ has been removed with the reducing coal gas that is discharged from the gas generator melting apparatus, the converted exhaust gas is mixed before the cyclone, which charges the dust discharged from the gas generator melting apparatus, into the gas generator melting apparatus.

The converted exhaust gas stream from which CO ₂ has been removed can be separated and used as a carrier gas for loading dust screened in a cyclone into a gas generator smelter.

A method for manufacturing molten iron according to the present invention may further include a bypass step of bypassing the total amount of exhaust gas that is discharged from. a multi-stage fluidized-bed reactor unit, and feeding it to a multi-stage fluidized-bed reactor unit during the closing time of the melter-gas generator or before the operation of the melter-gas generator.

A method for manufacturing molten iron according to the present invention may further include the steps of: separating the exhaust gas stream that is discharged through the multi-stage fluidized bed reactor unit and removing CO ₂ from the exhaust gas stream; and purging the multi-stage fluidized bed reactor unit by separating the converted exhaust gas stream from which CO ₂ has been removed and supplying the converted exhaust gas to each fluidized bed reactor.

Preferably, the amount of nitrogen contained in the reducing coal gas is 10.0 vol.% Or less.

A method for manufacturing molten iron according to the present invention may further include the steps of: separating a stream of exhaust gas that is discharged through the multi-stage fluidized bed reactor unit and removing CO ₂ contained in the exhaust gas; and separating the converted effluent gas stream from which CO ₂ has been removed and supplying it to the gasifier melting apparatus together with oxygen during the oxygen supply time to the gasifier melting apparatus.

The step of converting the iron-containing mixture into reduced material may include: a first stage of preheating the iron-containing mixture at a temperature of from 400 to 500 ° C; the second stage of re-preheating the preheated iron-containing mixture at a temperature of from 600 to 700 ° C; the third stage of pre-recovery re-pre-heated mixture at a temperature of from 700 to 800 ° C; and the fourth stage of the final recovery of the preliminary reduced iron-containing mixture at a temperature of from 770 to 850 ° C.

The oxidation state in the first and second stages can be 25% or less, the oxidation state in the third stage can be from 35 to 50%, and the oxidation state in the fourth stage can be 45% or more. Here, the oxidation state is obtained from the following equation: (vol% CO ₂ + vol% H ₂ O) / (vol% CO + vol% H ₂ + vol% CO ₂ + vol% H ₂ O) × 100 ; where CO, CO ₂ , H ₂ O and H ₂ are gases, each of which is contained in a reducing gas.

The second and third stages may include an oxygen supply step.

At the stage of manufacturing briquettes at high temperature, it is preferable that the grain size of the briquettes is in the range from 3 mm to 30 mm.

At the stage of formation of the compacted coal layer, it is preferable that the grain size of the briquette is in the range from 30 mm to 50 mm.

An integrated method for manufacturing steel according to the present invention includes the steps of: producing molten iron using the aforementioned method for producing molten iron; production of molten steel by removing impurities and carbon contained in molten iron; continuous casting of molten iron into a thin flat billet; hot rolling a thin flat billet to obtain a hot-rolled steel sheet.

At the stage of continuous casting of molten iron into a thin flat billet, molten steel can be continuously cast into a thin flat billet with a thickness of 40 mm to 100 mm.

At the stage of hot rolling a thin flat billet to obtain a hot-rolled steel sheet, the hot-rolled steel sheet may have a thickness of 0.8 mm to 2.0 mm.

The step of manufacturing molten steel may include the steps of: pretreating molten iron to remove phosphorus and sulfur contained in molten iron; removal of carbon and impurities contained in molten iron by supplying oxygen to molten iron; and manufacturing molten steel by removing impurities and dissolved gas by secondary purification of molten iron.

An integrated method for manufacturing steel may further include the steps of: converting pulverized iron-containing ores to reduced iron by reducing pulverized iron-containing ores as they pass through a multi-stage fluidized bed reactor unit in which the reactors are connected to each other in series; and the manufacture of reduced iron briquettes by briquetting the reduced iron at high temperature. At the stage of removing carbon and impurities contained in liquid iron, reduced iron briquettes and liquid iron can be mixed and carbon and impurities removed from them.

The step of converting the pulverized iron ores to reduced iron may include the steps of: preheating the pulverized iron ores at a temperature of from 600 to 700 ° C; preliminary recovery of preheated pulverized iron ores at a temperature of from 700 to 800 ° C; and the final reduction of the pre-reduced pulverized iron-containing ores at a temperature of from 770 to 850 ° C. to convert them to reduced iron.

A plant for manufacturing molten iron according to the present invention includes: a multi-stage fluidized-bed reactor unit for converting pulverized iron-containing ores that are mixed and dried, and additional raw materials into reduced material; installation for the manufacture of briquettes, connected to a multi-stage reactor unit with a fluidized bed, on which briquettes are made by briquetting the reduced material at high temperature; a machine for the manufacture of briquettes, which are used as a heat source, receiving them by briquetting small coals; a melter-gas generator for the production of molten steel, into which lump coals and briquettes made on a briquette machine are laid, and a compacted coal layer is formed, into which the reduced material is loaded from the briquette manufacturing plant and oxygen is supplied; and a pipeline for supplying reducing coal gas discharged from the smelter-gas generator to the multi-stage fluidized bed reactor unit.

A plant for manufacturing molten iron according to the present invention may further include a conduit for supplying a converted off-gas that separates a stream of off-gas that is discharged from the multi-stage fluidized bed reactor unit and supplies a converted off-gas from which CO ₂ is removed. An oxygen burner can be installed in the pipeline for supplying reducing coal gas to heat the reducing coal gas mixed with the converted exhaust gas before being fed to the multi-stage fluidized bed reactor unit.

Preferably, the transformed exhaust gas supply line includes a gas reforming apparatus for removing CO ₂ from the exhaust gas, which is discharged through the multi-stage fluidized bed reactor unit and separated.

Preferably, the transformed exhaust gas supply line includes a resin removal device to remove the resin from the exhaust gas, which is discharged through the multi-stage fluidized bed reactor unit and separated.

Preferably, the converted exhaust gas supply line includes a compressor for compressing the exhaust gas, which is discharged through the multi-stage fluidized bed reactor unit and separated, the resin removal device being installed upstream of the compressor.

The cyclone that loads the dust discharged from the melter-gas generator into the melter-gas generator can be attached to the melter-gas generator. The converted exhaust gas supply line may be connected to the front of the cyclone.

A pipeline for transporting gas by which the converted exhaust gas is separated, from which CO ₂ is removed, and through which the converted exhaust gas is supplied to the melter-gas generator as a carrier gas for transporting dust screened in the cyclone, can be connected to the back of the cyclone .

The multi-stage fluidized bed reactor unit may include a first pre-heating reactor in which the mixture is preheated at a temperature of from 400 to 500 ° C, a second pre-heating reactor that is connected to the first pre-heating reactor and in which the pre-heated iron-containing mixture is reheated at temperature from 600 to 700 ° C; a pre-reduction reactor, which is connected to the second pre-heating reactor and in which the pre-heated iron-containing mixture is pre-reduced at a temperature of from 700 to 800 ° C; and a final reduction reactor, which is connected to the pre-reduction reactor and in which the pre-reduced iron-containing mixture is finally reduced at a temperature of from 770 to 850 ° C.

Oxygen burners can be located between the second preheating furnace and the prereduction reactor and between the prereduction furnace and the final reduction reactor, and supplying reducing coal gas to each of the second preheating and preliminary reduction reactors after heating the reducing coal gas.

Preferably, the reducing coal feed pipe can be connected to a final reduction reactor.

A plant for producing molten iron according to the invention may further include a purge coal gas supply line for purging a multi-stage fluidized bed reactor unit by separating a stream of converted exhaust gas from which CO ₂ has been removed, and supplying the converted exhaust gas to each of the fluidized bed reactors.

A plant for manufacturing molten iron according to the invention may further include a loop for bypass circulation of the exhaust gas, which is connected to the multi-stage reactor unit with a fluidized bed and through which the entire amount of exhaust gas discharged from the multi-stage reactor unit with a fluidized bed is supplied to the multi-stage reactor unit with a fluidized bed layer.

A plant for manufacturing molten steel according to the present invention may further include a pipe for re-supplying coal gas, which separates the converted exhaust gas from which CO ₂ is removed, and delivers it to the melter-gas generator together with oxygen, while oxygen is supplied to it.

The integrated steel mill according to the present invention includes the aforementioned plant for manufacturing molten iron, a plant for manufacturing steel, which is connected to a plant for producing molten iron and which produces molten steel by removing impurities and carbon from molten iron; a machine for casting a thin flat billet, which is connected to a plant for manufacturing steel and on which the molten steel supplied from the plant is continuously poured into a thin flat billet; a hot rolling machine that is connected to a thin flat billet casting machine and on which a hot-rolled sheet is made by hot rolling a thin flat billet discharged from a thin flat billet casting machine.

An apparatus for manufacturing steel may include: an apparatus for pretreating molten iron, connected to an apparatus for manufacturing molten iron, in which phosphorus and sulfur contained in molten iron discharged from the apparatus are removed; a decarbonization unit connected to a unit for pre-treatment of molten iron, which removes carbon and impurities contained in the molten iron discharged from the unit for pre-treatment of molten iron; and a ladle connected to the decarbonization plant, where molten steel is produced by re-cleaning the molten iron, which is discharged from the decarbonization plant.

The integrated steel mill of the present invention may further include a second multi-stage fluidized bed reactor unit that separates the converted off-gas from which CO ₂ is removed and in which pulverized iron ores are converted to reduced material; and a second briquette making apparatus, which is connected to the first multi-stage fluidized bed reactor unit and on which briquettes are made by briquetting the reduced material at high temperature. A second briquette plant may supply reduced iron briquettes to the decarbonization plant.

The second multi-stage fluidized bed reactor unit may include: a pre-heating reactor for pre-heating pulverized iron ores at a temperature of from 600 to 700 ° C; a pre-reduction reactor, which is connected to a pre-heating reactor and in which pre-heated pre-heated pulverized iron-containing ores are reduced at a temperature of from 700 to 800 ° C; and a final reduction reactor, which is connected to the preliminary reduction reactor and in which the final reduction of the reduced iron-containing ores is finally reduced at a temperature of from 770 to 850 ° C.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent upon a detailed description of its typical embodiments with reference to the attached drawings, where:

1 is a schematic diagram illustrating an apparatus for manufacturing molten iron according to an embodiment of the present invention;

figure 2 is a graph illustrating the relationship between the corresponding amount of high-temperature reducing gas and the amount of high-temperature reducing gas produced in the melting apparatus-gas generator;

Fig. 3 is a schematic diagram illustrating a process for circulating reducing coal gas in a plant for manufacturing molten iron according to an embodiment of the present invention;

4 is a schematic diagram illustrating a process for circulating reducing coal gas after closing a melter-gas generator in a plant for manufacturing molten iron according to an embodiment of the present invention;

5 is a schematic diagram illustrating a purge process of a plant for manufacturing molten iron according to an embodiment of the present invention;

FIG. 6 is a graph illustrating the relationship between the oxidation state as a function of temperature and the Fe mixture inside the multi-stage fluidized bed reactor unit of the molten iron plant according to an embodiment of the present invention;

7 is a view illustrating an embodiment of an integrated steel mill using a plant for manufacturing molten iron according to an embodiment of the present invention;

Fig. 8 is a view illustrating another embodiment of an integrated steel mill using a plant for manufacturing molten iron according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Now, typical embodiments of the present invention will be described with reference to the attached drawings. However, the present invention can be carried out in various modifications, and thus it is not limited to the embodiments described below.

1 is a schematic diagram illustrating a plant 100 for manufacturing molten iron according to an embodiment of the present invention, where fine or lump coals and pulverized iron ores are directly used.

The apparatus 100 for manufacturing molten iron according to an embodiment of the present invention as main components includes a melting apparatus-gas generator 10, a multi-stage reactor unit 20 with a fluidized bed, a plant 30 for producing briquettes for producing briquettes, a machine 40 for briquetting for making briquettes, and an L50 feed pipe reducing coal gas. Installation 100 may include other accessories, if required.

As shown in FIG. 1, in a plant 100 for manufacturing molten iron according to an embodiment of the present invention, room temperature pulverized iron ores and additional raw materials having a grain size of 8 mm or less are temporarily stored in a hopper 21, then mixed to obtain iron mixture. The resulting mixture is dried in the drying apparatus 22 and then loaded into the reactor 24 of the first preheating of the multi-stage reactor unit 20 with a fluidized bed. An installation 23 is provided for loading at constant pressure between the drying apparatus 22 and the first preheating reactor 24, so that the mixture at normal pressure can be loaded into a multi-stage fluidized bed reactor unit 20, the pressure being maintained in the range from 0.15-03 MPa ( 1.5-3 atmospheres).

The iron-containing mixture is in contact with the flow of reducing gas discharged from the melting apparatus-gas generator 10, and it is reduced to approximately 90%, which is the target recovery, as it passes through the reactor 24 of the first pre-heating, reactor 25 of the second pre heating, the preliminary reduction reactor 26 and the final reduction reactor 27, which are connected in this order. The temperature of the iron-containing mixture is increased to more than 800 ° C, while it is restored by contact with the flow of reducing coal gas and the iron-containing mixture is converted into a high-temperature reduced material, while more than 30% of the additional raw materials in the iron-containing mixture are sintered. The multi-stage fluidized bed reactor unit 20 is implemented for four stages. However, the number of fluidized bed reactors is provided for illustrative purposes only and does not imply a limitation of the present invention. Accordingly, it is only required that the reactor unit 20 with a fluidized bed be implemented in multi-stage.

The recovered material that is recovered using the aforementioned method has an average grain size of about 2.0 mm. Direct loading of the reduced material into the melting apparatus-gas generator 10 leads to a significant loss in dispersion and deterioration of the ventilation properties of the compacted coal layer in the melting apparatus-gas generator 10. Therefore, the reduced material discharged from the final reactor 27 is sent to the briquette manufacturing apparatus 30, which connected to the final reduction reactor 27. Here, since the pressure inside the final reduction reactor 27 is maintained at 0.3 MPa (3 atmospheres), and the pressure inside the briquette manufacturing apparatus 30 is maintained at normal pressure, the reduced material is transferred from the final reduction reactor 27 to the briquette manufacturing plant 30 due to pressure differences.

In the briquette manufacturing apparatus 30, the high-temperature reduced material passing through the final reduction reactor 27 is temporarily stored in the loading hopper 31 and briquettes are mechanically molded into strips in the form of strips as they are passed between a pair of rolls at high temperature. Then, the strip-shaped briquettes are crushed with a crusher 35 so that they have a suitable size for loading them into the melter-gas generator 10, and the crushed briquettes are stored in the intermediate hopper 37. The briquettes are made directly at high temperature so that they have a predetermined strength and size. Preferably, the grain size in the briquettes is from 3 to 30 mm and the density is from about 3500 to 4200 kg / m ³ (3.5 to 4.2 t / m ³ ). When the grain size of the briquettes is less than 3 mm, the ventilation property deteriorates during loading into the melter-gas generator 10. When the grain size of the briquettes is more than 30 mm, it is difficult to produce briquettes and the strength when hot is deteriorated. Briquettes temporarily stored in the intermediate hopper 37 are continuously loaded into the melting apparatus-gas generator 10 by means of a loading unit 12 at high temperature and constant pressure, which allows briquettes to be loaded at normal pressure into the melting apparatus-gas generator 10, maintained at a pressure of 0.3 up to 0.35 MPa (from 3.0 to 3.5 atmospheres).

On the other hand, a compacted coal layer is formed inside the melter-gas generator 10 as a heat source for melting the briquettes. Raw coal for the formation of a layer of compacted coal inside the melting apparatus of the gas generator 10 must have a grain size of from 10 to 50 mm Lump coals having such a grain size are directly loaded into the melter-gas generator 10. On the other hand, the remaining small coals go through the process of sorting particles by size. In a briquetting machine 40, small coals having a grain size of 10 mm or less are crushed among the small coals stored in the storage hopper 41 to small coals having a grain size of 4 mm or less. The crushed fine coals are mixed with an appropriate amount of binder and additives using a mixer 43. The resulting mixture is transported to a briquette machine 45 and mechanically molded into briquettes under pressure. In this case, it is preferable that the grain size of the briquette is from 30 to 50 mm and its density is 800 kg / m ³ (0.8 t / m ³ ). When the grain size of the briquette is less than 30 mm, the ventilation inside the melting apparatus-gas generator 10 deteriorates. When the grain size of the briquette is more than 50 mm, it is difficult to produce briquettes and the warm-strength deteriorates. The pressure-molded briquettes are stored in the intermediate hopper 47.

Briquettes stored in the intermediate hopper 47 are loaded into the melter-gas generator 10 together with lump coals to form a layer of compacted coal. Briquettes loaded into the melter-gas generator 10 are converted into gas by the pyrolysis reaction, which proceeds in the upper part of the packed coal layer and by the combustion reaction, which proceeds in the lower part of the packed coal layer using oxygen. The high temperature reducing gas produced in the gasifier melter 10 by a gasification reaction is supplied to the multi-stage fluidized bed reactor unit 20 through a L50 feed pipe for supplying reducing coal gas, which is connected to the rear side of the final reduction reactor 27. High temperature reducing gas is used as a reducing agent and fluidizing gas. Coal reducing gas reduces and sinteres the iron-containing mixture as it flows through the final reduction reactor 27, the preliminary reduction reactor 26, the second preheating reactor 25, and the first preheating reactor 24. Coal reducing gas is discharged from the first preheater 24 and is dust free and cooled as it flows through a dust collector 51 using water.

An empty domed space is formed above the packed coal layer in the melter-gas generator 10, thereby reducing the gas flow rate. As a result, it is possible to prevent the release from the smelter-gasifier in large quantities of small coals contained in the briquette and small coals formed due to the sharply increasing temperature of the coal, which is loaded into the smelter-gasifier 10. Moreover, the empty domed space compensates for pressure fluctuations in melter-gas generator 10, caused by uneven changes in the amount of gas as a result of the direct use of coal. Coal is gasified and volatiles are removed from the coal, while it falls to the bottom of the bed of compacted coal and, ultimately, is burned with oxygen supplied through the tuyeres at the bottom of the melter-gasifier. While the flue gas rises through the bed of compacted coal, it is converted to a high-temperature reducing gas, and it is discharged from the melter-gas generator 10. Part of the flue gas is cleaned of dust and cooled when it passes through a dust collector 53 using water, provided that the pressure applied to the melter-gas generator 10 is maintained in the range from 0.3 to 0.35 MPa (from 3 to 3.5 atmospheres). Further, the reduced iron is finally reduced and melted with the help of reducing gas and the heat of combustion generated by gasification of coal and combustion as it falls in the bed of compacted coal with coal, and then the resulting molten iron is discharged.

The cyclone 14 is mounted on a melter-gas generator 10 to collect dust released to the outside. The cyclone 14 collects the exhaust gas generated in the melting apparatus-gas generator 10, and again feeds the accumulated dust into the melting apparatus-gas generator 10. Next, the cyclone 14 delivers, as reducing coal gas, the collected exhaust gas to the reduction reactor unit 20 with a fluidized bed. The carrier gas is supplied to the rear of the cyclone 14 to feed the dust screened in the cyclone 14 to the melter-gas generator 10.

On the other hand, the apparatus 100 for manufacturing molten iron according to an embodiment of the present invention includes a plant for replenishing reducing coal gas when the amount of high-temperature reducing coal gas produced in the melting apparatus-gas generator 10 is insufficient due to a change in operating conditions and a change in the quality of coal compared with a suitable amount of high-temperature reducing gas to be fed to the multi-stage fluidized-bed reactor unit 20 m layer. The replenishment process of reducing coal gas will be described in detail with reference to FIG.

Figure 2 is a graph illustrating the relationship between a suitable amount of high temperature reducing gas and the amount of high temperature reducing gas produced in a gas generator smelter, which shows an insufficient amount of high temperature reducing gas based on a recovery rate of 90%.

Due to changes in operating conditions in the smelter-gas generator 10 (shown in FIG. 1) and the properties of coal, the amount of high-temperature reducing coal gas produced in the smelting-gas generator 10 may not be sufficient compared to a suitable amount of high-temperature reducing gas that is needed feed into a multi-stage fluidized bed reactor unit 20 (shown in FIG. 1). At the same time, the operating conditions in the multi-stage fluidized-bed reactor unit 20 are controlled in order to prevent a deterioration in the recovery rate of the small reducible iron passing through the multi-stage fluidized-bed reactor unit 20, and a phenomenon in which heat inside the melter-gas generator 10 becomes insufficient from - due to the melting of reduced iron with a low recovery rate.

2, curve D represents the relationship between the reduction rate and the gas basic unit. The curves A to C represent the relationship between the reduction rate and the amount of gas produced in the melter-gas generator 10, which is converted into the main component of the gas, depending on the amount of volatile substances contained in the coal.

For example, if the recovery target is 90%, the required amount of reducing coal gas is 1,400 st.m ³ per tonne of pulverized iron ore in curve D. Conversely, if each amount of volatile substances contained in coal is 23%, 26% and 30%, each amount of reducing coal gas is 850 st.m ³ , 950 st.m ³ and 1050 st.m ³ per 1 ton of pulverized iron ore, so 550 st.m ³ , 450 st.m ^{3 are} required in appropriate cases and 350 st.m ³ . When the iron-containing mixture is reduced in a multi-stage fluidized bed reactor unit 20 in a state in which reducing coal gas is insufficient, it is not possible to obtain molten iron with the desired properties. Therefore, the desired recovery rate of the reduced material can be obtained by replenishing the amount of reducing coal gas.

The liquid iron manufacturing apparatus 100 shown in FIG. 1 further includes a L51 feed line for supplying a converted exhaust gas that separates an exhaust gas stream that is discharged from the multi-stage fluidized bed reactor unit 20 and supplies the converted exhaust gas from which the CO is removed ₂ . Pipeline L51 for supplying the converted exhaust gas is equipped with a compressor 76 and a gas reforming unit 77 to remove CO ₂ contained in the exhaust gas discharged from the first preheater 24. Additionally provided is a resin removal device upstream of the compressor 76, which removes a small amount of the resin contained in the gas that is supplied to the compressor 76, thereby preventing condensation of the resin inside the compressor 76.

In the installation 100 for the manufacture of molten iron, part of the exhaust gas stream discharged from the first preheater 24 and passing through a dust collector 51 using water is separated and passed through a resin removing device 75. The exhaust gas is then compressed using a compressor 76 and converted by a gas reforming unit 77. The converted exhaust gas is finally fed to the multi-stage fluidized bed reactor unit 20 through valve V772 to replenish an insufficient amount of reducing coal gas. In this case, the converted exhaust gas is supplied to the multi-stage fluidized bed reactor unit 20 after it is mixed with reducing coal gas. Since the temperature of the reducing coal gas decreases after mixing with the exhaust gas, the mixed gas is heated to the temperature necessary for reduction by using an oxygen burner 70 provided in the L50 conduit for supplying the reducing coal gas before the mixed gas is fed to the multi-stage reactor unit 20 with a fluidized bed.

By carrying out the above process, the following various effects can be obtained.

Firstly, the converted exhaust gas supply line L51 is connected to the front of the cyclone 14, and the converted room temperature exhaust gas is supplied to the cyclone 14, thereby preventing overheating of the cyclone 14. Therefore, the cyclone 14 effectively collects dust discharged from their smelting apparatus 10, thus preventing its dispersion.

Since the high-temperature coal gas discharged from the melter-gas generator 10 is mixed with the transformed off-gas at room temperature, the temperature of the reducing coal gas is lower than the temperature required to supply it to the multi-stage fluidized bed reactor unit 20. As a result, it is difficult to obtain the desired recovery rate of the recoverable material. Therefore, the recovery rate of the reduced material is increased by adjusting the temperature of the reducing coal gas mixed with the converted exhaust gas to the temperature necessary for reduction by using an oxygen burner. In particular, in the case of a plant 100 for producing molten iron, since the temperature of the exhaust gas passing through the multi-stage reactor unit 20 with a fluidized bed, that is, the temperature of the exhaust gas ultimately passing through the first preheating reactor 24, is relatively low, the amount consumed there is little water during cooling of the exhaust gas by using a dust collector 51 using water. Consequently, production costs are saved.

Moreover, in the case of dust and tar existing in the upper part of the melter-gas generator 10, since the reducing coal gas is converted as a converted exhaust gas after flowing through the multi-stage reactor unit 20 with a fluidized bed, the path for the circulation of dust and tar with a reducing coal gas is safe enough as a result of the removal of a significant amount of dust and tar. Therefore, it is possible to prevent interruption of the operation of the dust collector 51 using water due to condensation of the resin on the dust collector 51 using water. Further, in the event that a small-sized resin removal device 75 is installed in front of the compressor 76, it is also possible to prevent the destruction of the compressor 76 and the gas reforming unit 77 due to condensation of the resin.

In the off-gas passing through a water-using dust collector 51, the off-gas comprises 35 vol.% CO, 20 vol.% H ₂ and 40 vol.% CO ₂ . Therefore, it is preferable to remove CO ₂ using a gas reforming unit 77 in order to increase the reduction rate. The amount of offgas to be separated is controlled to 60% or less of the total amount of offgas that is discharged from the multi-stage fluidized bed reactor unit 20. Therefore, even if the amount of reducing coal gas for supplying to the multi-stage reactor unit 20 with a fluidized bed is insufficient, it is possible to replenish the missing amount of reducing coal gas. When the amount of exhaust gas to be separated is greater than 60 vol.%, The amount of converted exhaust gas to be supplied to the multi-stage fluidized bed reactor unit 20 after mixing it with reducing carbon gas increases, as a result of which the gas flow rate in the multi-stage reactor unit 20 fluidized bed becomes large. As a result, a large amount of the iron-containing mixture is dispersed outside the multi-stage fluidized bed reactor unit 20 and is lost.

Further, the amount of reducing gas to be supplied to the multi-stage fluidized-bed reactor unit 20 is controlled in the range from 1050 to 1400 stm ³ with respect to 1 ton of dusty iron-containing ores intended to be loaded into the multi-stage fluidized-bed reactor unit 20, thus effectively reducing the dusty iron-containing ores fed to the multi-stage fluidized bed reactor unit 20. More specifically, when the amount of reducing gas supplied to the multi-stage fluidized bed reactor unit 20 is less than 1050 stm ³ , it is difficult to obtain the desired recovery rate. When the amount of reducing gas supplied to the multi-stage fluidized bed reactor unit 20 is more than 1400 stm ³ , the ore is reduced and its particles adhere to each other due to the excess supply of reducing gas. Therefore, it is difficult to create a recovery condition in the fluidized bed.

In the case where CO _{2 is} removed using the gas reforming unit 77, it is preferable that the amount of CO ₂ contained in the converted exhaust gas passing through the gas reforming unit 77 is 3.0 vol.% Or less. When the amount of CO ₂ exceeds 3.0 vol.%, The reducing ability of the converted exhaust gas decreases and the converted exhaust gas becomes unusable.

As shown in FIG. 1, in a molten iron manufacturing apparatus 100 according to an embodiment of the present invention, a portion of the exhaust gas stream passing through the water-using dust collector 51 is separated and passed through the resin removing apparatus 75. The off-gas is compressed by a compressor 76 and converted by a gas reforming unit 77. Then, the converted exhaust gas can be used as a carrier gas for loading the dust screened in the cyclone 14 into the melter-gas generator after opening the valve V771 installed on the pipeline L52. In the case where the converted exhaust gas is used as a carrier gas, the amount of nitrogen that is used as a carrier gas can be reduced and the burning rate can be increased.

By opening the valve V773 installed on the L53 line for re-supplying the reducing gas, a separated stream of the converted exhaust gas from which CO ₂ is removed can be supplied to the melter-gas generator 10 during the time of supplying oxygen thereto. Therefore, the number of briquettes used can be reduced by supplying the converted exhaust gas to the melter-gas generator 10 and the distribution of the gas flow inside the coal layer can be improved.

FIG. 3 is a schematic diagram illustrating a process for circulating reducing coal gas in a liquid iron casting apparatus 100 according to an embodiment of the present invention. Figure 3 bold solid lines represent the pipelines for circulation through which circulate reducing coal gas. Other pipelines that are not related to pipelines for circulation are indicated by dashed lines. In the case of a closed valve, when the reducing coal gas is circulated, the reducing coal gas actually fills the front of the valve. Therefore, it is required to indicate this in the drawing, but in FIG. 3 this is omitted for convenience.

As shown in figure 3, the exhaust gas, which is compressed and converted, can be controlled using valves installed on the pipeline. More specifically, when the amount of reducing coal gas required for reduction in the multi-stage fluidized bed reactor unit 20 is insufficient, in the apparatus 100 for producing molten iron according to an embodiment of the present invention, the valves V51 to V53, V27, V762 and V772 are opened and others are closed thus replenishing with reducing coal gas a multi-stage fluidized bed reactor unit 20. The replenishment gas replenishment method shown in FIG. 3 is for illustrative purposes only and does not imply a limitation of this invention.

4 is a schematic diagram illustrating a process for circulating a reducing gas after the supply of reducing coal gas from the melting apparatus-gas generator 10 to the multi-stage fluidized bed reactor unit 20 in the liquid iron manufacturing apparatus 100 according to an embodiment of the present invention. Bold solid lines represent pipelines for circulation through which the reducing coal gas is circulated. Other pipelines, not related to the pipes for circulation, are shown in dotted lines. In the case of a closed valve, when the reducing coal gas is circulated, the reducing coal gas actually fills the front of the valve. Therefore, this should be indicated in the drawing, but this is not shown in FIG. 4 for convenience.

This process relates to the case where the melter-gas generator 10 is turned off and it is not possible to supply reducing gas to the multi-stage fluidized bed reactor unit 20. In this case, the entire amount of exhaust gas that is discharged from the multi-stage reactor unit 20 with a fluidized bed is discharged through a conduit L54 for circulating the exhaust gas and is supplied to the multi-stage reactor unit 20 with a fluidized bed.

Further, in the melter-gas generator 10, the stop is sometimes caused by malfunctions in the experiment. In this case, since gas is not produced in the melting apparatus-gas generator 10, it is necessary to circulate the exhaust gas in order to support the drilling of the fluidized bed in a multi-stage reactor unit 20 with a fluidized bed connected to the melting apparatus-gas generator 10. In this case, the loading of briquettes, lump coal and briquettes are stopped and the release of reducing gas from the melting apparatus-gas generator 10 is stopped to close the melting apparatus-gas generator 10. Then, the valve V7 is closed 62. All exhaust gas discharged from the multi-stage fluidized bed reactor unit 20 is passed through a valve V51 and compressed using a compressor 76. At the same time, valve V761 installed on the L54 line for circulating the exhaust gas is opened and the exhaust gas is continuously circulated. Valves V27, V53, V762, V771, V772 and V773 are all closed in this process to prevent leakage of off-gas towards the melter-gas generator 10. Consequently, it is possible to continuously circulate off-gas while preventing leak-out of the gas inward melting apparatus-gas generator 10. As a result, it is possible to prevent settling of the fluidized bed.

5 is a schematic diagram illustrating a purge process of a plant for manufacturing molten iron according to an embodiment of the present invention. Pipes through which part of the compressed and converted exhaust gas is circulated to purge the multi-stage fluidized-bed reactor unit 20 are shown as solid solid lines. In the case of a closed valve, when the reducing coal gas is circulated, the reducing coal gas actually fills the front of the valve. Therefore, it is required to indicate this in the drawing, but in FIG. 5 this is omitted for convenience.

When purging during operation is required, the converted purge exhaust gas is supplied to the multi-stage fluidized bed reactor unit 20 through a L55 purge coal gas supply line. Since the main process is continuously performed during such a purge, a portion of the converted exhaust gas is mixed with the exhaust gas from the smelter-gas generator 10 through the L51 feed pipe for supplying the converted exhaust gas and fed to the multi-stage fluidized bed reactor unit 20, and a portion of the converted exhaust gas is supplied in the tuyere of the melter-gas generator 10 or in the device for burning dust through the pipeline L52 for carrier gas and the pipe L53 for re-supplying recovery aza in the same way as during normal operation. Such a converted exhaust gas stream is shown in bold solid lines.

The multi-stage fluidized bed reactor unit 20 includes internal devices, such as a cyclone, riser, discharge pipe, discharge line, which are built into it. It is necessary to maintain a fluidized state in the internal devices so that the reducing coal gas and the iron-containing mixture can be constantly in a fluidized state. Therefore, a purge line must be provided to prevent blocking of internal devices. Purge is usually performed using nitrogen. However, when reducing coal gas is used for purging, additional nitrogen is not required, thereby significantly reducing the amount of nitrogen consumed.

In the case where the purge is performed using nitrogen, since the flow of exhaust gas that is discharged from the multi-stage reactor unit 20 with a fluidized bed is separated and converted, and then again sent to the multi-stage reactor unit 20 with a fluidized bed, nitrogen accumulates in the converted exhaust gas and the nitrogen concentration in the entire reducing coal gas supplied to the multi-stage fluidized bed reactor unit 20 ultimately increases. As a result, when the concentration of nitrogen, which is an inert gas, exceeds 10.0 vol.% Of the total reducing coal gas, the ore reduction rate in the multi-stage fluidized bed reactor unit 20 decreases. Therefore, as described above, the nitrogen concentration in the reducing coal gas is reduced to 10 vol.% Or less by using the converted exhaust gas as a purge gas, thus, it is possible to prevent the accumulation of nitrogen in the reducing coal gas intended to be fed to the multi-stage reactor unit for 20 s fluid bed.

The exhaust gas stream that is discharged through the multi-stage fluidized bed reactor unit 20 is separated and CO _{2 is} removed from the exhaust gas. The converted exhaust gas is supplied to each of the fluidized bed reactors 20. Although not shown in FIG. 5, the coal gas feed line L55, which is connected to each of the fluidized bed reactors 20, is again separated to supply the converted exhaust gas to the internal devices of the respective fluidized bed reactors 20 and to be able to purge the internal devices , if required. More specifically, the amount of converted exhaust gas that is supplied as purge gas can be controlled using valve V24 installed on the L55 purge gas supply line.

Hereinafter, the operating conditions of the multi-stage fluidized bed reactor unit 20 in the method for manufacturing molten iron according to the present invention will be described in detail. In particular, in the present invention, the optimum operating conditions are determined, taking into account the fact that it is largely important to recover the iron-containing mixture using reducing coal gas.

FIG. 6 is a graph illustrating the relationship between the oxidation state and the Fe mixture as a function of the temperatures of the multi-stage fluidized bed reactor unit 20 in a molten iron manufacturing apparatus according to an embodiment of the present invention, which shows stable phase regions of the Fe mixture in each of the reactors with fluid bed.

Here, the oxidation state is calculated using the amount of each gas, such as CO, CO ₂ , H ₂ and H ₂ O contained in the reducing gas. The degree of oxidation denotes a measure of reducing ability. The oxidation state is determined as (vol% CO ₂ + vol% H ₂ O) / (vol% CO + vol% H ₂ + vol% CO ₂ + vol% H ₂ O) × 100. In Fig.6 100 - the oxidation state is used as a value for the Y axis for convenience, which means the degree of reduction as a concept opposite to the oxidation state. Therefore, if this value rises to the top of the Y axis, it is easy to trigger a reduction reaction. Conversely, if it descends to the bottom of the Y axis, it is easy to cause an oxidation reaction.

In the method of manufacturing molten iron according to an embodiment of the present invention, the multi-stage fluidized bed reactor unit 20 (shown in FIG. 1) uses directly coal gas as a reducing gas. Therefore, it is possible to operate with a relatively low value of the main gas component of 1400 stm ³ / t, and with a relatively short residence time of a maximum of six minutes, with respect to each fluidized bed reactor, compared to other fluidized bed reduction processes such as FINMET, FIOR, IRON CARBIDE, etc., which directly use natural gas. Therefore, in the fluidized-bed reduction process, as shown in FIG. 6, in the case of the first preheating reactor in which the first stage of preheating the iron-containing mixture is carried out, it is preferable that the reduction in the fluidized bed proceeds in the phase stability region of Fe ₃ O ₄ . In the case of a second preheater reactor, in which the second stage of re-preheating the iron-containing mixture is carried out, it is preferable that the reduction in the fluidized bed proceeds in the region of stability of the FeO phase. In the case of a prereduction reactor in which a third stage for prereducing a preheated iron-containing mixture is carried out and a final reactor in which a fourth stage for a final reduction of a pre-reduced iron-containing mixture is performed, it is preferable that the reduction in the fluidized bed proceeds in the phase stability region of the Fe. By maintaining the above regions, it is possible to minimize the amount of iron-containing mixture stabilized in the Fe ₃ O ₄ phase in which the reaction rate is very slow as the first pre-heating reactor and the second pre-heating reactor pass. Further, it is possible to sufficiently reduce the iron-containing mixture as it passes through the prereduction reactor and the final reactor, in which the stability region of the Fe phase is formed.

In a multi-stage fluidized-bed reactor unit 20, in which operation is performed at a relatively low value of the main gas component, it is important to control the temperature of the respective fluidized-bed reactors and the composition of the reducing coal gas to fix the Fe phase stability region in each fluidized-bed reactor.

In order to create fluidized-bed reduction conditions in each of the fluidized-bed reactors, it is preferable to maintain the temperature of the fluidized bed in the first preheater in the range of 400 to 500 ° C., and the temperature of the fluidized bed in the second preheater in the range of 600 to 700 ° С, the temperature of the bubbling fluidized bed in the preliminary reduction reactor is maintained in the range from 700 to 800 ° С and the temperature of the bubbling fluid the fluidized bed in the final reduction reactor to maintain in the range from 770 to 850 ° C. It is further preferable to maintain the composition of the reducing coal gas supplied to each fluidized bed reactor in order to fix a certain degree of oxidation in each of the fluidized bed reactors, specifically 45% or more in the first preheater, from 35% to 50% in the second preheater heating and 25% or less in the pre-reduction reactor and in the final reduction reactor.

With regard to the appropriate temperature and composition of the reducing coal gas in each of the reactors to maintain the above conditions, the temperature of the reducing coal gas that is discharged from the gas generator smelter and which is supplied to the bubbling fluidized bed of the final reactor is too high, i.e., the temperature is about 1000 ° C. Therefore, when reducing coal gas is supplied to the final reactor as it is, the iron-containing mixture in the final reactor overheats and the ores stick together. Therefore, it is necessary to cool the reducing coal gas supplied to the final reactor. The cooling of the final reactor is made possible by mixing the transformed off-gas at room temperature and the reducing coal gas discharged from the smelter-gas generator. Further, the supplied amount of the transformed off-gas at room temperature is controlled depending on the amount of reducing gas required for the final reactor. As a result, the reducing coal gas supplied to the final reactor during the mixing process can be subcooled below a suitable temperature. Therefore, the temperature of the reducing coal gas is maintained to be suitable by supplying oxygen to the reducing coal gas and by partially burning the reducing coal gas after mixing the transformed room temperature exhaust gas with the reducing coal gas.

Further, a burner 72 is installed between the second preheating reactor 25 and the preliminary reduction reactor 26, and a burner 71 is installed between the preliminary reduction reactor 26 and the final reactor 27 for supplying oxygen to the reducing coal gas, which is discharged from the reactors 20 and for partial burning of the reducing coal gas . In this way, the oxidation state of the reducing coal gas in the bubbling fluidized bed of the prereduction reactor 26 is maintained at 35% or less. Further, the oxidation state of the reducing coal gas in the bubbling fluidized bed of the second preheating reactor 26 is maintained in the range of 40% to 60%. Moreover, the reducing coal gas that is discharged from the second preheating reactor 25 is supplied to the bubbling fluidized bed of the first preheating reactor 24 as it is. As a result, the oxidation state in the multi-stage fluidized bed reactor unit 20 is controlled.

Therefore, according to the present invention, when the amount of reducing coal gas is not enough in the above-mentioned real process, it is possible to replenish the insufficient amount and satisfy the ideal working conditions of the multi-stage fluidized bed reactor unit 20.

Table 1 shows the temperature of the fluidized bed and the oxidation state of the reducing gas for each of the reactors in the four-stage reactor unit 20 with the fluidized bed and the Fe-O phase contained in the ore discharged from each of the fluidized bed reactors at each stage.

Table 1 First Preheating Reactor Second Preheating Reactor Prereactor Reactor Final Reactor Temperature 460 ° C 650 ° C 800 ° C 840 ° C Oxidation state 50.0% 40.0% 24.0% 10.5% Fe ₂ O ₃ 62.0 wt.% 48.3 wt.% - - Fe ₃ O ₄ 13.2 wt.% 12.0 wt.% - - FeO - 29.7 wt.% 60.3 wt.% 19.4 wt.% Fe - - 15.6 wt.% 54.1 wt.% Recovery rate 2.0% 20.0% 50.0% 85.1%

In table 1, the main gas component is 1200 st.m ³ / t. ore. As shown in Table 1, by controlling the temperature of the fluidized bed and the oxidation state for each of the fluidized bed reactors in the multi-stage fluidized bed reactor unit 20 within the aforementioned range, the amount of Fe ₃ O ₄ generated in the first preheater is minimized , and Fe ₃ O _{4 is} not further formed in the second preheating reactor. As a result, a reduction rate of 80% or more with respect to pulverized iron ores can be obtained in the final reactor by reducing FeO to Fe.

In the aforementioned molten iron production plant 100, fine or lump coals and pulverized iron ores can be directly used, and the plant 100 is compact in general, so it is suitable to use the plant 100 in an integrated steel mill by connecting the installation 100 to an integrated steel mill. Therefore, it is possible to directly produce hot-rolled steel sheet from small or lumpy coals and pulverized iron ores by operating a plant for manufacturing molten iron according to an embodiment of the present invention in a mini-mill, which is an integrated steel manufacturing process.

Hereinafter, an integrated steel mill operating an apparatus 100 for manufacturing molten iron according to an embodiment of the present invention will be described in more detail. Such an integrated steel mill is for illustrative purposes only and is not a limitation of the present invention.

FIG. 7 is a view illustrating an embodiment of an integrated steel mill operating an apparatus 100 for manufacturing molten iron according to an embodiment of the present invention. 7 schematically shows an integrated steel mill 1000 for the direct manufacture of hot-rolled steel sheet from small or lumpy coals and pulverized iron-containing ores. The molten iron making apparatus 100 shown in FIG. 7 has the same construction as the aforementioned molten iron making apparatus 100 according to an embodiment of the present invention, therefore, a description thereof is omitted for convenience. The following describes other settings, with the exception of the installation 100 for the manufacture of molten iron.

The integrated steel mill shown in FIG. 7 includes a plant 100 for producing molten iron, a plant 200 for manufacturing steel, which is connected to a plant 100 for producing molten iron and which produces molten steel by removing impurities and carbon from molten cast iron, a plant 300 for of casting a thin flat billet which is connected to a steel making apparatus 200 and which continuously pours molten steel supplied from the installation into a thin flat billet, a machine 400 hot-rolling steel, which is connected to the installation 300 for casting a thin flat billet and which produces a hot-rolled sheet by hot rolling a thin flat billet discharged from the installation 300 for casting a thin flat billet. In addition, the integrated steel mill 100 may include additional installations if required.

Fig. 7 illustrates in detail an example of a method for manufacturing steel by operating the above plants. Installation 200 for the manufacture of steel includes installation 61 for pre-treatment of liquid iron, where phosphorus and sulfur contained in liquid iron are removed, installation 64 for decarbonization, which is connected to installation 61 for pre-treatment of liquid iron and in which carbon and impurities contained in molten iron discharged from the installation 61 for the preliminary processing of molten iron, and a ladle 67, which is connected to the installation 64 for decarbonization and which produce molten steel by re-cleaning ductile iron discharged from carbonization unit 64.

Liquid iron discharged from the melter-gas generator 10 is periodically discharged into a liquid iron pretreatment unit 61 having a refractory vessel, and transported to a downstream process. The pre-treatment of molten iron is carried out during transportation by feeding a desulfurizing agent, which is flux, to the molten iron contained in the installation 61 for the pre-treatment of molten iron, and by removing sulfur and phosphorus contained in the molten iron. As a result, the sulfur content in the molten iron is adjusted to 0.006% or less. It is preferable to use CaO or CaCO ₃ as a desulfurizing agent in the pre-treatment of molten iron.

Next, the molten iron from the installation for pretreatment of molten iron, which went through the preliminary processing of molten iron, is discharged into the installation 64 for decarbonization converter type. During the unloading process, it is preferable that the molten slag, which is formed during the pre-treatment of molten iron and floats on the surface of molten iron, does not penetrate the decarbonization unit 64. Oxidative purification is performed by blowing oxygen at high speed into molten iron after molten iron is fed to decarbonization unit 64. During oxidative purification, impurities dissolved in molten iron, such as carbon, silicon, phosphorus and manganese, are removed by oxidation and molten iron is converted to molten steel. The oxidized impurities are dissolved in liquid slag on molten steel using CaO, CaF ₂ , dolomite, etc., which are fed to the converter and removed from the molten steel. After oxidation, the treatment is completed, the molten steel is discharged from the carbonization unit 64 into a ladle 67, which is a refractory tank, and then transported to a downstream process. By such a method of manufacturing steel, the amount of carbon contained in the molten steel is adjusted to 2.0 mass% or less.

The molten steel passes through a second cleaning process in bucket 67. The molten steel is heated by an arc discharge, which is induced on the molten steel by transferring high voltage through an electrode rod, and excited by inert gas blown from the bottom of the bucket 67, so that uniform temperature distribution, and components, and flotation separation of non-metallic materials embedded in molten steel. Further, the sulfur component, which is present in a small amount in the molten steel, can be intensively removed by blowing Ca-Si powders into the molten steel, if necessary. Next, the above processes are completed, molten iron passes through a gas removal process in which a vacuum bath is connected to the upper side of the refractory vessel to create a vacuum state, and gas components such as carbon, N ₂ and H ₂ are removed, thereby increasing the purity of the molten become. It is preferable to prevent a decrease in the temperature of the molten steel by using the heat of combustion generated by blowing oxygen during the gas removal process and by burning a component of the exhaust gas.

The ladle 67 is transported to an apparatus 300 for casting thin flat preforms after the aforementioned second cleaning process. The molten steel is discharged from the ladle 67 into a casting device 71, which is placed above the apparatus 300 for casting a thin flat billet, and fed into the apparatus 73 for casting a thin flat billet through a casting device 71, for casting a thin flat billet with a thickness of 40 mm to 100 mm. The spilled thin flat billet is compressed on a rough rolling mill 75, which is directly connected to the casting unit 73, shaping the bar to a thickness of 20 to 30 mm. Then, the pressed thin flat preform is heated with a heater 77 and twisted on a coiler 79. When the thickness of the thin flat preform is less than 40 mm, it easily breaks. When the thickness of the thin flat billet is more than 100 mm, it can overload the rigid rolling mill 75.

The twisted whetstone is unwound again and passed through a rust remover 83 to remove rust formed on the surface of the whetstone. Then the bar is transferred to the final rolling mill and it is rolled to obtain a rolled steel sheet with a thickness of 0.8 to 2.0 mm. The rolled steel sheet is cooled using a refrigerator 87 and twisted 89, like a finally rolled steel sheet. Hot rolled steel sheet with a thickness of 0.8 to 2.0 mm is suitable for consumer use.

In a steel mill 1000, including a cast iron plant 100 according to an embodiment of the present invention, it is an advantage that a hot-rolled steel sheet can be manufactured using directly fine or lump coals and pulverized iron ores through the processes described above. Therefore, the raw material is not limited in time of manufacturing molten iron, and it is possible to produce hot rolled steel sheet using compact means.

FIG. 8 is a view illustrating another embodiment of an integrated steel mill 2000 operating an apparatus 100 for producing molten iron according to an embodiment of the present invention. Fig. 8 illustrates a method for supplying reduced iron to a decarbonization plant, which is one of the elements of a steel plant, using a second multi-stage fluidized bed reactor unit 90 and a second briquette plant 35, which is provided with the integrated steel mill 2000. The integrated steel mill the plant 2000 shown in FIG. 8 has the same structure as the integrated steel mill 1000, with the exception of some. Therefore, the description of the same parts is omitted for convenience, and thus, a description of the other parts will be presented in detail.

Further, in the described complex steel mill 2000, the above-described multi-stage fluidized bed reactor unit 20 connected to the gas melting apparatus 10 relates to the so-called first fluidized-bed reactor unit, and another multi-stage fluidized-bed reactor unit refers to the so-called multistage fluidized bed reactor unit. Further, a briquette making apparatus 30, which is connected to the rear of the first multi-stage fluidized bed reactor unit 20, relates to a so-called first briquette making apparatus, and another briquette making apparatus 35, which is connected to the rear of the second reactor block 90 s fluidized bed, refers to the so-called second installation for the manufacture of briquettes.

As shown in FIG. 8, the integrated steel mill 2000 includes a second multi-stage fluidized bed reactor unit 90 and a second briquette making machine 35. The second multi-stage fluidized bed reactor unit 90 is an apparatus for recovering pulverized iron-containing ores, which are fed into it from an iron-containing bin 91. The multi-stage fluidized-bed reactor unit 90 is made of a three-stage fluidized-bed reactor unit including a first pre-heating reactor 93, a preliminary reduction reactor 95, and a final reduction reactor 97. In each of the reactors 93, 95 and 97, a bubbling fluidized bed is formed.

In the second multi-stage fluidized bed reactor unit 90 in the first preheating reactor 93, the pulverized iron ores are preheated at a temperature of from 600 to 700 ° C., in the prereduction reactor 95 connected to the preheating reactor 93, the preheated iron ores are preliminarily reduced at a temperature from 700 to 800 ° C., and in the final reduction reactor 97 connected to the preliminary reduction reactor 95, it is finally reduced Pour pre-reduced iron ores at a temperature of from 770 to 850 ° C.

The second multi-stage fluidized bed reactor unit 90 feeds a portion of the exhaust gas discharged from the first multi-stage fluidized bed reactor unit 20 through an additional pipe for circulating the reducing gas from the final reactor 97, and it converts dried and mixed iron ores having a grain size of 8 mm or less, to recover iron, which is reduced by more than 92% as the exhaust gas is successively circulated through each of reactors 93, 95 and 97. In FIG. 8, the second the multi-stage reactor block 90 with a fluidized bed is presented in the form of a three-stage reactor block with a fluidized bed, but only for purposes of illustration, and this does not mean a limitation of the present invention. The fluidized bed reactor unit 90 can be supplemented to have a different number of stages.

Further, in the second briquette making apparatus 35, the high-temperature reduced iron is temporarily stored in the loading hopper 36 and the reduced iron is briquetted therein by injection molding, passing the reduced iron through a pair of rolls 37. Then, the briquettes are crushed using a crusher 38 and stored in the hopper 39 for supply of briquettes.

Preferably, the amount of reducing coal gas supplied to the second multi-stage fluidized bed reactor unit 90 is 40 vol% or more of the total amount of exhaust gas discharged from the first multi-stage fluidized bed reactor unit 20. On the other hand, in the process of supplying a portion of the exhaust gas discharged from the first multi-stage fluidized bed reactor unit 20 to the second multi-stage fluidized bed reactor unit 90, the resin is removed by the resin removal device 75. Preferably, the amount of CO ₂ contained in the converted exhaust gas is 3.0 vol.% Or less. The reducing coal gas passing through the second multi-stage fluidized bed reactor unit 90 is cleaned of dust and cooled with a dust collector 55 using water, and then discharged to the outside.

Although not shown in FIG. 8, it is preferable to partially burn the converted exhaust gas by supplying oxygen therein to increase the temperature of the exhaust gas using the calorific value, and the elevated temperature is 800 to 850 ° C.

Since reduced iron is produced using iron-containing ores and purified reducing gas, 90% or more of the reduced iron is composed of pure iron, and sulfur is contained in a very low concentration, thereby increasing the purity of the molten steel that is made in the decarbonization unit 64, when the reduced iron is loaded into a decarbonization unit 64.

Hereinafter, the present invention will be described in detail with reference to an experimental example. However, this experimental example is provided for illustrative purposes only and is not intended to limit the present invention.

Experimental example

The melt and slag are produced using the aforementioned plant for the production of molten iron according to the implementation of the present invention.

In an experimental example according to an embodiment of the present invention, the melting apparatus-gas generator 10 was maintained at a pressure of 0.32 MPa (3.2 atm) and the amount of oxygen supplied to burn coal inside the melting apparatus-gas generator 10 was adjusted to 550 stm ³ per 1 ton cast iron. Further, the amount of pulverized ore and additional raw materials was adjusted to 1.5 tons and 0.35 tons, respectively. The amount of coal supplied to the smelter-gas generator 20, was regulated in the range from 0.9 to 1.0 tons, based on the production of molten iron in the amount of 1 ton. The performance of the installation for the manufacture of molten iron was determined equal to 85 tons / hour under the above working conditions.

Experimental operation was carried out according to an embodiment of the present invention, and the compositions of the resulting molten iron and slag discharged from the gasifier melting apparatus were as follows. Table 2 shows the composition of molten iron according to an embodiment of the present invention, and table 3 shows the composition of slag according to an embodiment of the present invention.

table 2 Temperature FROM Si Mn R S 1500 ° C 4.5 wt.% 0.5 wt.% 0.17 wt.% 0.09 wt.% 0.04 wt.%

As shown in table 2, the temperature of the molten iron produced using the experimental example according to the present invention was about 1500 ° C, and the amount of impurities in the molten iron, excluding iron, was as described above.

Table 3 Temperature SiO ₂ CaO MgO Al ₂ O ₃ Basicity CaO / SiO ₂ 1520 ° C 31.1 wt.% 35.7 wt.% 12.5 wt.% 13.5 wt.% 1.15 wt.%

As shown in table 3, the temperature of the molten iron produced using the experimental example according to the present invention was about 1520 ° C, and the basicity was 1.15.

As can be understood from table 2, the temperature of the molten iron produced according to the present invention was essentially 1500 ° C, and the amounts of Si, P and S were so small that it met the quality standard of molten iron for conventional steelmaking. Further, as can be understood from table 3, the temperature of the slag was essentially 1520 ° C, and the basicity of the slag, which is a measure of the quality of the slag, was essentially 1.15. Therefore, in the method of manufacturing molten iron according to an embodiment of the present invention, even if fine or lump coals and pulverized iron ores are used, in contrast to the traditional invention, the melt quality was similar to the quality of molten iron in the traditional method.

According to the present invention described above, since molten iron having a high quality that meets the quality standard of molten iron for the manufacture of steel can be produced continuously by the use of fine or lump coals or pulverized iron ores, the blast furnace process that was used in the complex steel mill can be replaced . Therefore, it is possible to use cheap raw materials and not to carry out the sintering and coking processes, thereby increasing the profitability of the integrated steel mill and preventing the formation of polluting materials during the sintering and coking processes.

Further, in the apparatus for manufacturing molten iron according to the present invention, the exhaust gas stream that is discharged from the multi-stage fluidized bed reactor unit is separated and converted. The converted exhaust gas is fed to a multi-stage fluidized bed reactor unit. Therefore, it is possible to replenish the missing amount of reducing coal gas, thereby providing technological flexibility.

Moreover, the converted room temperature exhaust gas, which is cooled, can be fed to the front of the cyclone, thereby preventing overheating of the cyclone.

According to the present invention, the exhaust gas that is discharged from the multi-stage fluidized bed reactor unit is used as a carrier gas, thereby reducing the amount of nitrogen used as the carrier gas.

Further, the converted exhaust gas, which is converted according to the present invention, can again be supplied to the melting apparatus-gas generator together with oxygen, thereby lowering the ratio of coal consumption and improving the distribution of the gas stream in the coal layer.

While the present invention has been shown and described in detail with reference to its typical embodiments, it will be understood by those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (44)

1. A method of manufacturing molten iron, including the manufacture of an iron-containing mixture by mixing pulverized iron-containing ores and additional raw materials and drying the resulting mixture, converting the iron-containing mixture into reduced material by reducing and sintering as the iron-containing mixture passes through a multi-stage fluidized bed reactor unit, fluidized reactors the layer of which is connected in series with each other, the manufacture of briquettes by briquetting the reduced material at a high temperature, the formation of a layer of compacted coal by loading lump coals and briquettes, which are obtained by briquetting small coals, into a gas-melting apparatus, as a heat source for melting briquettes, producing molten iron by loading briquettes into a gas-melting apparatus connected to a multi-stage a fluidized bed reactor unit and supplying oxygen to a gasifier melting apparatus, supplying a reducing coal gas discharged from a gasogen melting apparatus a non-reactor, into the fluidized-bed reactor unit, separating the exhaust gas stream that is discharged through the multi-stage reactor unit, and removing CO ₂ from the exhaust gas, supplying the converted exhaust gas to the multi-stage fluidized-bed reactor unit. 2. The method according to claim 1, further comprising mixing the converted exhaust gas from which CO ₂ has been removed with reducing coal gas that is discharged from the gas generator smelter, and heating the reducing coal gas mixed with the converted exhaust gas before supplying it to a multi-stage fluidized-bed reactor unit for controlling the temperature of the reducing coal gas to the temperature required to recover the iron-containing mixture in the multi-stage reactor Loka fluidized bed. 3. The method according to claim 2, in which the converted exhaust gas is heated using an oxygen burner, at the stage of heating before feeding the reducing coal gas mixed with the converted exhaust gas into a multistage fluidized bed reactor unit. 4. The method according to claim 2, in which at the stage of separating the flow of exhaust gas that is discharged through a multi-stage reactor unit with a fluidized bed, and removing CO ₂ from the exhaust gas, the amount of separated exhaust gas is preferably 60 vol.% Of the total amount of exhaust gas which is discharged from fluidized bed reactors. 5. The method according to claim 2, in which the amount of converted exhaust gas is maintained in the range from 1050 st.m ³ to 1400 st.m ³ per 1 ton of pulverized iron-containing ores. 6. The method according to claim 2, in which at the stage of mixing the converted exhaust gas from which CO ₂ is removed with carbon reducing gas that is discharged from the gas generator smelter, the amount of CO ₂ contained in the converted exhaust gas is preferably 3, 0 vol.% Or less. 7. The method according to claim 2, in which the separated off-gas is compressed at the stage of separating the off-gas stream discharged from the multi-stage fluidized bed reactor unit and removing CO ₂ from the off-gas. 8. The method according to claim 2, further comprising the step of separating the exhaust gas stream that is discharged through the multi-stage reactor unit with a fluidized bed, and removing the resin from the exhaust gas before the separation of the exhaust gas stream that is discharged from the multi-stage reactor unit with a fluidized bed, and removal of CO ₂ from the exhaust gas. 9. The method according to claim 2, in which, at the stage of mixing the converted exhaust gas from which CO ₂ is removed, with reducing coal gas that is discharged from the gas generator smelting apparatus, the converted exhaust gas is mixed before the cyclone that charges the dust discharged from the smelter apparatus-gas generator in the melting apparatus-gas generator. 10. The method according to claim 9, in which the stream of the converted exhaust gas from which CO ₂ is removed is separated and used as a carrier gas for loading dust screened in a cyclone into a gas generator melting apparatus. 11. The method according to claim 1, further comprising purging the multi-stage fluidized bed reactor unit with transformed exhaust gas. 12. The method according to claim 11, in which the amount of nitrogen contained in the reducing coal gas is 10 vol.% Or less. 13. The method according to claim 1, further comprising separating the converted exhaust gas and supplying it to the melter-gas generator together with oxygen during the supply of oxygen to it. 14. The method according to claim 1, in which the stage of converting the iron-containing mixture into the reduced material includes a first stage of pre-heating the iron-containing mixture at a temperature of from 400 to 500 ° C, a second stage of re-heating the pre-heated iron-containing mixture at a temperature of from 600 to 700 ° C. , the third stage of the preliminary recovery of the re-preheated mixture at a temperature of from 700 to 800 ° C, and the fourth stage of the final recovery of the pre-reduced iron oxide zhaschey mixture at a temperature of from 770 to 850 ° C. 15. The method according to 14, in which the oxidation state in the first and second stages is 25% or less, the oxidation state in the third stage is 35 to 50%, the oxidation state in the fourth stage is 45% or more, where the oxidation state is obtained from the following equation: (vol% CO ₂ + vol% H ₂ O) / (vol% CO + vol% H ₂ + vol% CO ₂ + vol% H ₂ O) · 100; CO, CO ₂ , H ₂ O and H ₂ are gases, each of which is contained in a reducing gas. 16. The method according to 14, in which the second and third stages include the stage of oxygen supply. 17. The method according to claim 1, in which at the stage of manufacturing briquettes at high temperature, the grain size of the briquettes is in the range from 3 to 30 mm 18. The method according to claim 1, in which at the stage of formation of a layer of compacted coal, the grain size of the briquettes is in the range from 30 to 50 mm 19. A method of producing molten iron, including the manufacture of an iron-containing mixture by mixing pulverized iron-containing ores and additional raw materials and drying the resulting mixture, converting the iron-containing mixture into reduced material by reduction and sintering as the iron-containing mixture passes through a multi-stage fluidized-bed reactor unit, fluidized reactors a layer of which is connected in series with each other, the manufacture of briquettes briquetting recovered mater at a high temperature, the formation of a layer of compacted coal by loading lump coals and briquettes, which are obtained by briquetting fine coals, into a melting apparatus-gas generator, as a heat source for melting briquettes, making molten iron by loading briquettes into a melting apparatus-gas generator, connected to a multi-stage fluidized-bed reactor unit and oxygen supply to the melting apparatus-gas generator, supply of reducing coal gas discharged from the melting apparatus-g the generator into the fluidized-bed reactor block, bypassing the entire amount of exhaust gas that is discharged from the multi-stage fluidized-bed reactor block, and supplying it to the multi-stage fluidized-bed reactor block during the closing time of the melter-gas generator or before operation of the melting apparatus gas generator apparatus. 20. An integrated method for processing iron-containing materials, including the manufacture of molten iron, using the method of manufacturing molten iron according to claim 1, the manufacture of molten steel by removing impurities and carbon contained in molten iron, the continuous casting of molten steel into a thin flat billet, hot rolling of thin flat blanks for hot rolled steel sheet. 21. The complex method according to claim 20, in which at the stage of continuous casting of molten steel into a thin flat billet, molten steel is continuously cast into a thin flat billet with a thickness of 40 to 100 mm. 22. The complex method according to claim 20, in which at the stage of hot rolling a thin flat billet to obtain a hot-rolled steel sheet, a hot-rolled steel sheet is made with a thickness of 0.8 to 2.0 mm. 23. The complex method according to claim 20, in which the step of manufacturing molten steel includes pre-treatment of molten iron to remove phosphorus and sulfur contained in molten iron, removing carbon and impurities contained in molten iron by supplying oxygen to molten iron, and manufacturing molten steel by removing impurities and dissolved gas by a second cleaning of molten iron. 24. The integrated method according to item 23, further comprising converting the pulverized iron-containing ores into reduced iron by reducing the pulverized iron-containing ores as they pass through a multi-stage fluidized-bed reactor unit, the reactors of which are connected in series with each other, and manufacturing briquettes from reduced iron by briquetting reduced iron at a high temperature, in which, at the stage of removing carbon and impurities contained in molten iron, brie is mixed reduced iron chum and liquid iron, and carbon and impurities are removed from them. 25. The complex method according to paragraph 24, wherein the step of converting the pulverized iron ores to reduced iron comprises the steps of preheating the pulverized iron containing ores at a temperature of from 600 to 700 ° C, preliminarily recovering the preheated pulverized iron containing ores at a temperature of from 700 to 800 ° C , and the final reduction of pre-reduced pulverized iron-containing ores at a temperature of from 770 to 850 ° C to convert them into reduced iron. 26. Installation for the manufacture of molten iron, including a multi-stage reactor unit with a fluidized bed for converting pulverized iron ores that are mixed and dried, and additional raw materials into reduced material, an installation for the manufacture of briquettes by briquetting the reduced material at high temperature, which is connected to a multi-stage reactor fluidized bed unit, briquetting machine for the production of briquettes, which is used as a heat source, by br small coal coals, melting apparatus-gas generator for the production of molten iron with the possibility of loading lump coals and briquettes made in a briquetting machine, forming a layer of compacted coal, loading of reduced material from a briquette and oxygen supply plant, a pipeline for supplying reducing coal gas supplying reducing coal gas discharged from the smelter-gas generator to the multi-stage fluidized-bed reactor unit layer, a pipe for supplying the converted exhaust gas, which separates the exhaust gas stream discharged from the multi-stage fluidized bed reactor unit, and delivers the converted exhaust gas from which CO ₂ is removed. 27. The installation for the manufacture of molten iron according to claim 26, wherein an oxygen burner is installed in the pipeline for supplying reducing coal gas to heat the reducing coal gas mixed with the converted exhaust gas before being supplied to the multi-stage fluidized bed reactor unit. 28. The installation for the manufacture of molten iron according to item 27, in which the pipeline for supplying the converted exhaust gas includes an installation for reforming the gas to remove the CO ₂ contained in the exhaust gas, which is discharged through a multi-stage reactor unit with a fluidized bed and separated. 29. The installation for the manufacture of molten iron according to item 27, in which the pipeline for supplying the converted exhaust gas includes a device for removing resin from the exhaust gas, which is discharged through a multi-stage reactor unit with a fluidized bed and separated. 30. The installation for manufacturing molten iron according to clause 29, in which the pipe for supplying the converted exhaust gas includes a compressor for compressing the exhaust gas, which is discharged through a multi-stage reactor unit with a fluidized bed and which is separated, and a resin removal device is installed in front of the compressor. 31. The installation for the manufacture of molten iron according to item 27, in which the melting apparatus gas generator is equipped with a cyclone loading dust discharged from the melting apparatus gas generator into the melting apparatus gas generator, and a pipe for supplying the converted exhaust gas is connected to the front of the cyclone. 32. The installation for the manufacture of molten iron according to clause 31, in which a pipeline for transporting gas separating the converted exhaust gas from which CO ₂ is removed and supplying the converted exhaust gas to the melting apparatus gas generator as a carrier gas for transporting dust screened in a cyclone, connected to the back of the cyclone. 33. Installation for the manufacture of molten iron according to item 27, in which the multi-stage reactor unit with a fluidized bed includes a reactor for the first pre-heating of the iron-containing mixture at a temperature of from 400 to 500 ° C, a second pre-heating reactor, which is connected to the first pre-heating reactor and which reheat the pre-heated iron-containing mixture at a temperature of from 600 to 700 ° C, a pre-reduction reactor, which is connected to the second pre-heating reactor and in which the pre-heated mixture is pre-re-reduced at a temperature of from 700 to 800 ° C., and a final reduction reactor, which is connected to the pre-reduction reactor and in which the pre-reduced iron-containing mixture is finally reduced, is restored at a temperature of from 770 to 850 ° C. 34. A plant for manufacturing molten iron according to claim 33, wherein the oxygen burners are located between the second preheating reactor and the prereduction reactor, and between the prereduction reactor and the final reduction reactor, with the possibility of supplying reducing coal gas to the second preheating reactor and the reactor pre-reduction after heating the reducing coal gas. 35. Installation for the manufacture of molten iron according to clause 33, in which the pipeline for supplying reducing coal gas is connected to the final reduction reactor. 36. The installation for the manufacture of molten iron according to p, further comprising a pipe for supplying a purge of coal gas for purging a multi-stage reactor unit with a fluidized bed by separating the flow of the converted exhaust gas and supplying the converted exhaust gas to each of the fluidized bed reactors. 37. Installation for the manufacture of molten iron, including a multi-stage reactor unit with a fluidized bed for converting pulverized iron-containing ores, which are mixed and dried, and additional raw materials into reduced material, an installation for the manufacture of briquettes by briquetting the reduced material at high temperature, which is connected to a multi-stage reactor fluidized bed unit, briquetting machine for the production of briquettes, which is used as a heat source, by br small coal coquetting, gas melting apparatus for producing molten iron with the possibility of loading lump coals and briquettes into it, manufactured in a briquetting machine, forming a layer of compacted coal, loading reduced material from a briquette and oxygen supply plant, a pipeline for supplying reducing coal gas supplying reducing coal gas discharged from the smelter-gas generator to the multi-stage fluidized-bed reactor unit, t a bypass for the bypass circulation of the exhaust gas, which is connected to a multi-stage reactor unit with a fluidized bed with the ability to supply the total amount of exhaust gas discharged from the multi-stage reactor unit with a fluidized bed, in a multi-stage reactor unit with a fluidized bed. 38. Installation for the manufacture of molten iron according to clause 37, further comprising a pipeline for re-supply of coal gas, separating the stream of the converted exhaust gas and feeding it to the melting apparatus-gas generator together with oxygen, during the supply of oxygen to it. 39. The integrated steel mill, including the installation for the manufacture of molten iron according to claim 1, the installation for the manufacture of steel connected to the installation for the manufacture of molten steel, which produces molten steel by removing impurities and carbon from molten iron, a machine for casting thin flat billets connected to the installation for the manufacture of steel for continuous casting of molten steel supplied from the installation into a thin flat billet, a hot rolling machine connected to a machine for casting a thin flat billet to produce a hot-rolled sheet by hot rolling a thin flat billet unloaded from a thin flat billet casting machine. 40. The integrated steel mill of claim 39, wherein the steelmaking plant includes a liquid iron pretreatment unit coupled to a liquid ironmaking plant to remove phosphorus and sulfur contained in the molten iron unloaded from the installation, and a decarbonization plant connected to the installation for pretreatment of molten iron, which removes carbon and impurities contained in liquid cast iron, unloaded from the installation for pretreatment of molten iron, and for Connected with installation for decarbonization, which produces the molten steel by re-refining molten iron discharged from the decarbonization installation. 41. The integrated steel mill according to claim 40, further comprising a second multi-stage fluidized bed reactor unit configured to separate the transformed discharge gas from which CO ₂ has been removed and convert the pulverized iron-containing ores into reduced material, and a second briquette manufacturing apparatus, which is connected to the first multistage fluidized bed reactor, producing briquettes by briquetting the reduced material at high temperature, and and for the manufacture of briquettes made with the possibility of feeding briquettes of reduced iron in the installation for decarbonization. 42. The integrated steel mill of Claim 41, wherein the second multi-stage fluidized bed reactor unit includes a preheater for preheating the pulverized iron ores at a temperature of from 600 to 700 ° C., a prereduction reactor that is connected to the preheating reactor, for pre-reduction of pre-heated pulverized iron-containing ores at a temperature of from 700 to 800 ° C; and a final reduction reactor, which is connected to the react rum prereduction for finally reducing the pre-reduced iron ore dust at a temperature of 770 to 850 ° C. Priorities for items: 12/05/2003 according to claims 1, 4-7, 9-11, 14-26, 28, 31-35 and 37-42; 12/03/2004 according to claims 2, 3, 8, 12, 13, 27, 29, 30 and 36.

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