KR101128939B1 - An apparatus for manufacturing a molten iron directly using fine or lump coals and fine iron ores, the method thereof, the integrated steel mill using the same and the method thereof - Google Patents

Abstract

Provided is an apparatus for manufacturing molten iron using directly fine or lump coals and fine iron-containing ores, a method thereof, an integrated steel mill using the same, and a method thereof.. The method of manufacturing the molten iron comprises the steps of: manufacturing iron-containing mixture by mixing fine iron-containing ores and supplementary raw materials and by drying the resultant mixture, converting the iron-containing mixture to a reduced material by reducing and sintering while passing the iron-containing mixture through multi-stage fluidizedbed reactor unit, which are sequentially connected to each other, manufacturing briquettes by briquetting the reduced material at high temperature, forming a coal packed bed by charging lump coals and briquettes which are made by briquetting fine coals, into a melter-gasifier as heat sources for melting the briquettes, і manufacturing molten iron by charging the briquettes into the melter-gasifier connected to the multi-stage fluidized-bed reactor unit and by supplying oxygen into the melter-gasifier, and supplying reducing coal-gas exhausted from the melter-gasifier into the multi-stage fluidized-bed reactor unit.

Description

METAL MANUFACTURING APPARATUS USING DIRECTLY OR PARTICLE OF CARBON AND PRESENT IRON OILS AND METHOD OF MANUFACTURING THE SOLID STEEL IRON ORES, THE METHOD THEREOF, THE INTEGRATED STEEL MILL USING THE SAME AND THE METHOD THEREOF}

1 is a schematic view showing a molten iron manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the appropriate amount of hot reducing gas versus the amount of hot reducing gas generated in a melt gasifier.

Figure 3 is a schematic diagram showing a process of circulating the reducing coal gas in the molten iron manufacturing apparatus according to an embodiment of the present invention.

4 is a schematic diagram illustrating a process of circulating a coal gas for reducing after closing a melt gasifier in a molten iron manufacturing apparatus according to an embodiment of the present invention.

5 is a schematic diagram illustrating a process of purging a flow reduction path in a molten iron manufacturing apparatus according to an embodiment of the present invention.

6 is a graph showing the relationship between the oxidation degree and the Fe compound phase according to the temperature of the fluid reduction furnace in the molten iron manufacturing apparatus according to an embodiment of the present invention.                 

7 is a view showing an example of an integrated steel manufacturing apparatus using a molten iron manufacturing apparatus according to an embodiment of the present invention.

8 is a view showing another example of the integrated steel manufacturing apparatus using a molten iron manufacturing apparatus according to an embodiment of the present invention.

The present invention relates to an apparatus for manufacturing molten iron, a method for manufacturing the same, an integrated iron apparatus using the same, and a method for manufacturing the same. More specifically, a molten iron manufacturing apparatus using direct powder or bulk coal or powdered iron ore and its manufacture The present invention relates to a method and an integrated steelmaking apparatus using the same, and a method for manufacturing the same.

The steel industry is a key industry that supplies basic materials to the entire industry, such as automobiles, shipbuilding, home appliances, construction, etc., and is one of the oldest industries with the development of mankind. The steel mill, which plays a pivotal role in the steel industry, first manufactures molten pig iron, molten iron, using iron ore and coal as raw materials, and then manufactures and supplies steel to each customer.

Currently, about 60% of the world's iron production comes from the blast furnace method developed since the 14th century. The blast furnace method is a method of manufacturing molten iron by reducing iron ore to iron by putting together coke prepared from sintering process and coke made from bituminous coal into a blast furnace. As such, the blast furnace method, which constitutes a large scale of molten iron production equipment, requires a raw material having a certain level or more of strength and a particle size capable of ensuring the breathability of the furnace due to its reaction characteristics, and as described above, a carbon source used as a fuel and a reducing agent. It depends on coke processed specific raw coal and iron source mainly depends on sintered ore which has undergone a series of bulking process. As a result, the current blast furnace method necessarily involves preliminary processing of raw materials such as coke manufacturing facilities and sintering facilities. Therefore, it is not only necessary to construct auxiliary facilities other than blast furnaces, but also Due to the need for the installation of environmental pollution prevention equipment, there is a problem in that the manufacturing cost is rapidly increased due to the large investment cost.

In order to solve the problems of the blast furnace method, molten reduction of molten iron is produced by directly using general coal as a fuel and a reducing agent in steel mills around the world, and by directly using spectroscopy that occupies 80% or more of the world's ore production as an iron source. Many efforts are being made in the development of the steelmaking method.

US Patent No. 5,534,046 discloses a method for producing molten iron using small iron ore and bulk coal. Here, since the whole apparatus consists of a multi-stage fluidized-bed reduction reactor and a packed-bed melt gasification furnace connected to the final stage, the powdered iron source can be directly used due to the fluidized bed characteristics of the fluidized-bed reduction reactor. However, since a certain level of voids must be secured in the packed bed formed in the melt gasifier, the range of suitable particle size of ordinary coal directly charged into the melt gasifier is limited, and the powdered iron source reduced in the fluidized bed reduction furnace is melted gasifier. Since it is necessary to charge continuously, there is a problem that requires a special charging method. In particular, since the use particle size range of the ordinary coal used as fuel and reducing agent is limited, there is a problem in that a considerable amount of powdered ordinary coal generated in the coal mining, transportation and yarding stages cannot be used. In addition, in the case of the iron source, in the case of the process consisting of a packed-bed reduction furnace, a considerable amount of powdered iron source cannot be used. In the process of the fluidized-bed reduction furnace, a means for continuously charging the powdered reduced iron discharged from the reduction furnace into the molten gasifier is used. Should be prepared separately.

U. S. Patent No. 5,961, 690 discloses a method for producing molten pig iron or molten steel as a whole and a plant for carrying out the method. Here, a method and apparatus for manufacturing molten iron by connecting a multistage flow reduction path and a melt gasification furnace while preventing sticking are disclosed. In addition, in this case, a part of reducing gas flowing from the final reducing furnace to the preliminary reducing furnace is branched, cooled and cooled to room temperature, and then CO ₂ is removed and fed back to the final reducing furnace to increase the amount of reducing gas to reduce iron ore. The gas that is re-supplied to the reduction furnace is maintained at the final reduction furnace temperature by finally raising the temperature to a suitable temperature using a separate heating device before being supplied to the final reduction furnace.

In addition, as a method of raising the temperature of reducing gas at room temperature, a method of using a heat exchange method by contact with a hot gas supplied separately or by burning a portion of the reducing gas at room temperature and heating itself by the heat of combustion is considered. However, in the former case, a separate fuel gas is required to generate a hot gas, and in the latter case, reducing gas components such as CO and H ₂ in the reducing gas supplied to the final reduction furnace are reduced by partial combustion of the room temperature gas. There is a problem. In addition, the former and the latter both have to heat up the gas at room temperature directly, the thermal efficiency is lowered in the temperature increase process, thereby increasing the energy consumption in the process.

And U. S. Patent No. 5,961, 690 discloses a method of cooling a waste gasification furnace exhaust gas to a temperature suitable for supplying the final reduction furnace by branching and mixing the exhaust gas directly into the melting gasification furnace before heating a part of the reducing gas re-supplied to the final reduction furnace. Also disclosed.

On the other hand, tar and dust generated by deterioration and devolatilization of coal in the upper part of the melt gasification furnace during actual operation are sequentially passed through the multi-stage flow reduction reactor together with the reducing gas discharged from the melt gasification furnace. In this case, the tar is gradually pyrolyzed and extinguished in the reducing gas, and the dust enters the spectral ore stream which crosses the reducing gas in each flow reducing reactor and passes through the multistage liquid reducing reactor in sequence, and then again into the melt gasification furnace. Circulated to Therefore, the amount of dust and tar contained in the reducing gas is reduced through the multi-stage flow reduction reactor.

However, in the method and apparatus disclosed in US Pat. No. 5,961,690, the reducing gas branched from the final reduction furnace passes through only one fluidized bed, thus containing a large amount of dust and tar. Therefore, in the process of cooling the branched reducing gas and removing and compressing CO ₂ , the tar contained in the gas condenses in the apparatuses provided as means for cooling the reducing gas, removing and compressing CO ₂ , and thus fail in operation of the devices. Will cause. In addition, the method and apparatus disclosed in US Pat. No. 5,961,690 requires a separate water cooling system to cool the branched high temperature reducing gas to a low temperature in addition to the water cooling system of the gas finally discharged from the multistage flow reduction reactor. In addition, the amount of cooling water used increases and the overall process is heavily loaded.

The present invention is to solve the above-mentioned problems, using a powdery or lumped coal or powdered iron ore, the reduction rate of iron ore in the step of reducing the iron ore by using the reducing coal gas generated from the coal To provide a molten iron manufacturing apparatus and its molten iron manufacturing method that can be maintained well.

In addition, the present invention is to provide a hot-rolled steel sheet having a good quality while compactly constructing the overall apparatus and process by providing a consistent iron manufacturing apparatus and a method of manufacturing the integrated iron using the above-described molten iron manufacturing apparatus and its manufacturing method.

In the manufacturing method of molten iron according to the present invention, by mixing and drying the powdered iron ore and secondary raw materials to produce an iron-containing mixture, the iron-containing mixture is reduced and calcined while passing through a multi-stage flow reduction reactor to a reducing body Converting, reducing the high-temperature agglomerate to produce a compact, and charging coal briquettes formed by compacting the coal and powdered ordinary coal as a heat source for melting the compact into a melt gasifier to form a coal-filled layer. , Charging a compacted material into a molten gasifier connected to a multistage flow reduction reactor, injecting oxygen into the molten gasifier, and preparing molten iron; and supplying coal gas for reduction discharged from the molten gasifier to the fluidized reactor. Steps.                     

Further, the molten iron production method according to the present invention is to branch the exhaust gas discharged through the back to the multi-stage fluidized-bed reactor and removing the CO _2, reducing coal gas exiting the reformed exhaust gas to remove the CO ₂ from the melter-gasifier and the mixing And controlling the reducing coal gas at a temperature necessary for reducing the iron-containing mixture in the flowing reduction reactor by heating the reducing coal gas mixed with the reforming flue gas before supplying it to the flow reduction reactor. Do.

In the step of raising the temperature of the reducing coal gas mixed with the reformed exhaust gas before supplying it to the flow reduction reactor, the reformed exhaust gas may be heated by heating with an oxygen burner.

In the step of removing the CO ₂ by branching the exhaust gas discharged from the flow reduction reactor, the amount of branched exhaust gas is preferably 60 vol% or less of the total amount of exhaust gas discharged from the flow reduction reactor.

Iron-containing ore on the amount of the reformed exhaust gas can be maintained in the range of 1 minute per ton of 1050Nm ³ to 1400Nm ^3.

In the step of mixing the reformed exhaust gas from which the above-described CO ₂ is removed with the reducing coal gas discharged from the melting gasifier, the CO ₂ content in the reformed exhaust gas is preferably 3.0% by volume or less.

In the step of removing CO ₂ by branching the exhaust gas discharged from the above-described flow reduction path, the branched exhaust gas may be boosted.

Prior to the step of branching the exhaust gas discharged from the flow reduction path to remove the CO ₂ , it is preferable to further include the step of branching the exhaust gas discharged through the multi-stage flow reduction path to remove the tar.

In the step of mixing the reformed flue gas from which CO ₂ is removed with the reducing coal gas discharged from the melt gasifier, the dust discharged from the melt gasifier may be mixed at the front end of a cyclone charged into the melt gasifier. have.

The reformed flue gas from which CO ₂ has been removed may be branched and used as a carrier gas for charging the dust isolated from the cyclone into the melting gasifier.

The molten iron manufacturing method according to the present invention may further include the step of bypassing the total amount of exhaust gas discharged from the multi-stage flow reduction reactor at the time of closing the molten gasification furnace or starting the molten gasification furnace to supply the multistage flow reduction reactor. have.

] The method according to the present invention, the fluidized-bed reactor to be supplied to each fluidized-bed reactor to branch the exhaust gas discharged through the back to the multi-stage fluidized-bed reactor to branch the reformed exhaust gas to remove the step, and CO ₂ to remove CO ₂ The method may further include purging.

Here, the nitrogen content in the reducing coal gas is preferably 10.0% by volume or less.

] The method according to the present invention is to branch the exhaust gas discharged through the back to the multi-stage fluidized-bed reactor to branch the reformed exhaust gas to remove the step, and CO ₂ to remove CO ₂ further comprising: accepting with Oxygen blown into the melter gasifier It may further include.

In the step of converting the iron-containing mixture into a reducing body, the first step of preheating the iron-containing mixture to 400 ~ 500 ℃, the second step of reheating the preheated iron-containing mixture to 600 ~ 700 ℃, reheated iron-containing mixture It may include a third step of preliminarily reducing to 700 ~ 800 ℃, and a fourth step of converting the pre-reduced iron-containing mixture to 770 ~ 850 ℃ the final reduction to a reducing body.

The oxidation degree in the first and second steps described above may be 25% or less, the oxidation degree in the third step may be 35 to 50%, and the oxidation degree in the fourth step may be 45% or more. Here, the oxidation degree is (CO ₂ vol% + H ₂ O vol%) / (CO vol% + H ₂ vol% + CO ₂ vol% + with respect to CO, CO ₂ , H ₂ O and H ₂ gases in the reducing gas H ₂ O volume%) × 100%.

The second and third steps may comprise blowing oxygen.

In the step of producing the compacted material, it is preferable to compact the high temperature so that the particle size of the compacted material is 3 mm to 30 mm.

In the step of forming the coal filling layer, it is preferable to manufacture so that the particle diameter of the coal briquettes 30mm to 50mm.

The integrated steelmaking method according to the present invention comprises the steps of preparing molten iron by the above-described molten iron manufacturing method, removing molten iron and decarburizing to produce molten steel, continuously casting molten steel into thin slabs, and Hot rolling the thin slab to produce a hot rolled steel sheet.                     

Here, in the continuous casting of molten steel into a thin slab, molten steel may be continuously cast into a thin slab having a thickness of 40 mm to 100 mm.

In the step of manufacturing a hot rolled steel sheet, the hot rolled steel sheet may be manufactured to a thickness of 0.8 mm to 2.0 mm.

The step of manufacturing molten steel includes a preliminary treatment step for removing phosphorus and sulfur in the molten iron, blowing carbon into the molten iron to remove carbon and impurities in the molten iron, and refining the molten iron to remove impurities and dissolved gases. It may comprise the step of manufacturing molten steel.

In the integrated steelmaking method according to the present invention, while passing through another multi-stage flow reduction reactor in which another powdery iron-containing ore is sequentially connected, the reduced iron is converted to reduced iron, and the reduced iron is hot-hardened to reduce reduced iron compacts. It may further comprise the step of manufacturing. In the step of removing carbon and impurities in molten iron, reduced iron compacted material and molten iron may be mixed to remove carbon and impurities.

The step of converting the other powdered iron ore to reduced iron includes: preheating the other powdered iron ore to 600 to 700 ° C., preliminarily reducing the preheated powdered iron ore to 700 to 800 ° C., And converting the pre-reduced powdered iron ore into reduced iron by final reduction at 770 to 850 ° C.

The apparatus for manufacturing molten iron according to the present invention is a multistage flow reduction reactor for converting mixed and dried powdered iron ore and secondary raw materials into a reducing body, and connected to the multistage flow reduction furnace to produce a compacted material by high temperature agglomeration of the reducing body. A compacted coal production device, a coal briquette manufacturing device for producing coal briquettes for compacting powdered coal, as a heat source for melting the compacted material, and a coal-filled layer is formed therein by charging coal briquettes from the coal and coal briquette manufacturing device. A molten gasification furnace for charging molten iron from the apparatus and blowing oxygen into the molten gas to produce molten iron, and a reducing coal gas supply pipe for supplying the reducing coal gas discharged from the molten gasification furnace to the flow reduction reactor.

The apparatus for manufacturing molten iron according to the present invention further includes a reformed exhaust gas supply pipe for supplying reformed exhaust gas from which CO ₂ is removed by branching exhaust gas discharged through a multi-stage flow reduction path, and flowing a reducing coal gas mixed with reformed exhaust gas. An oxygen burner that is heated up before supplying to the reduction furnace may be installed in the coal gas supply pipe for reduction.

The reformed exhaust gas supply pipe is preferably provided with a gas reformer for removing CO ₂ from the exhaust gas branched by passing through a multi-stage flow reduction path.

The reformed exhaust gas supply pipe is preferably provided with a tar removal device for removing tar from the exhaust gas branched by passing through a multi-stage flow reduction path.

The reformed flue gas supply pipe is provided with a compressor for compressing the flue gas discharged through the multi-stage flow reduction path and branched, and the tar removal device is preferably provided at the front of the compressor.

A cyclone for charging the dust discharged from the molten gasifier into the molten gasifier may be installed in the molten gasifier, and a reformed exhaust gas supply pipe may be connected to the front end of the cyclone.                     

A transport gas pipe for branching the reformed exhaust gas from which the CO ₂ has been removed may be connected to the cyclone rear end for injecting the dust isolated from the cyclone as a transport gas charged into the melting gasifier.

The multi-stage flow reduction furnace is a first preheating furnace for preheating the iron-containing mixture at 400 to 500 ° C, a second preheating furnace for reheating the iron-containing mixture preheated at 600 to 700 ° C in connection with the first preheating furnace, 2 Preliminary reduction furnace for preliminary reduction of the iron-containing mixture reheated in connection with the preheating furnace to 700-800 ° C, and final reduction furnace for final reduction of the iron-containing mixture preliminarily reduced to 770-850 ° C in connection with the preliminary reduction furnace. It may include.

An oxygen burner may be installed between the second preheating furnace and the preliminary reduction reactor, and between the preliminary reduction reactor and the final reduction reactor to heat the reducing coal gas and supply it to the second preheating furnace and the preliminary reduction reactor, respectively.

It is preferable that a reduction coal gas supply pipe is connected to the final reduction furnace.

The molten iron manufacturing apparatus according to the present invention may further include a purge coal gas supply pipe for branching the reformed exhaust gas from which CO ₂ has been removed and supplying it to each flow reduction furnace to purge each flow reduction furnace.

The apparatus for manufacturing molten iron according to the present invention may further include an exhaust gas bypass circulation pipe connected to the flow reduction path and supplying the entire exhaust gas discharged therefrom to the flow reduction path in multiple stages.

The apparatus for manufacturing molten iron according to the present invention may further include a coal gas resupply pipe branching the reformed exhaust gas from which CO ₂ has been removed and blown together when oxygen is blown into the molten gasifier.

The integrated steel making apparatus according to the present invention is connected to the above-described molten iron manufacturing apparatus, molten iron manufacturing apparatus to remove impurities from molten iron and decarburize the molten steel to manufacture molten steel. The thin slab casting machine, and a hot rolling mill connected to the thin slab casting machine to hot roll the thin slab discharged from the thin slab casting machine to produce a hot rolled sheet.

The steelmaking apparatus is connected to a molten iron manufacturing apparatus to remove phosphorus and sulfur in the molten iron discharged from the molten iron manufacturing apparatus, and a carbon preliminary component connected to the molten iron preprocessing apparatus to remove carbon and impurities in the molten iron discharged to the molten iron preliminary processing apparatus. The decarburization apparatus may include a ladle connected to the decarburization apparatus and secondly refining molten iron discharged therefrom to produce molten steel.

The integrated iron making apparatus according to the present invention is connected to another multistage flow reduction reactor for branching reformed flue gas from which CO ₂ has been removed to convert another powdery iron-containing ore into a reducing body, and to another multistage flow reduction reactor. Another compacted material producing apparatus for producing reduced iron compacted material by high temperature compaction may be further included. Another compacted material manufacturing apparatus can supply reduced iron compacted material to the decarburization apparatus.

Another multistage flow reduction furnace is a preheating preheating another powdered iron ore to 600 ~ 700 ℃, and preliminary reduction of preheating of the powdered iron ore preheated in connection with the preheating furnace to 700 ~ 800 ℃. Furnace, and connected to the preliminary reduction furnace may include a final reduction furnace for the final reduction of the preform reduced iron-containing ore to 770 ~ 850 ℃.

Hereinafter, with reference to the accompanying Figures 1 to 8 will be described an embodiment of the present invention. These examples are merely to illustrate the invention, but the invention is not limited thereto.

1 is a schematic view showing a molten iron manufacturing apparatus 100 according to an embodiment of the present invention, schematically showing a molten iron manufacturing apparatus 100 that directly uses powdered or bulky coal and powdered iron ore. .

The molten iron manufacturing apparatus 100 according to an embodiment of the present invention shown in Figure 1 is largely a molten gasifier 10, a multi-stage flow reduction furnace 20, compacted material manufacturing apparatus 30, coal briquette manufacturing apparatus 40 ), And a reducing coal gas supply pipe (L50). And other devices as needed.

As shown in FIG. 1, in the apparatus for manufacturing molten iron 100 according to an embodiment of the present invention, an iron-containing mixture is prepared by temporarily storing spectroscopic and secondary raw materials having a particle diameter of 8 mm or less in the hopper 21 and then temporarily mixing them. Next, the water is charged into the first preheating furnace 24, which is one of the flow reduction furnaces 20, through the dryer 22 to remove moisture. A uniform back pressure charging device 23 is provided between the dryer 22 and the first preheating furnace 24 to allow the iron-containing mixture to be charged into the flow reduction furnace 20 maintained at 1.5 to 3 atm under normal pressure. .

The iron-containing mixture is discharged from the molten gasifier 10 while sequentially passing through four stages of the first preheating furnace 24, the second preheating furnace 25, the preliminary reduction reactor 26 and the final reduction reactor 27. In contact with the reducing coal gas stream is reduced to a reduction rate of 90%, the target reduction rate. The iron-containing mixture is heated to 800 ° C. or more in contact with the reducing coal gas stream and is converted into a high-temperature reducing body in which at least 30% of the auxiliary material is calcined in the iron-containing mixture. Although the four stages of the flow reduction furnace 20 are shown in FIG. 1, this is merely to illustrate the present invention, but the present invention is not limited thereto. Therefore, it is only necessary to configure the flow reduction furnace 20 in multiple stages.

Reducing material reduced in this way, when the average particle diameter is about 2.0mm when directly charged into the molten gasifier 10, a significant amount of scattering loss and deterioration of the air permeability of the coal packed bed in the molten gasifier (10). Therefore, in order to manufacture the compacted material by high temperature compaction of the reducing body discharged from the final reduction path 27, the reduced material is transferred to the compacted material manufacturing apparatus 30 connected to the final reduction path 27. Here, since the final reduction path 27 is maintained at a pressure of 3 atm and the compacted material manufacturing apparatus 30 is maintained at normal pressure, the compacted material manufacturing apparatus from the final reduced path 27 by reducing pressure by this pressure difference. Transfer to 30.

In the compacted material manufacturing apparatus 30, after storing the high temperature reducing body which passed through the final reduction path 27 once in the charging hopper 31, it is mechanically pressurized while passing between a pair of rolls 33 in a high temperature state. Molding produces a compact in the form of a strip. Next, the compacted material in strip form is crushed to a size suitable for charging the molten gasifier 10 by the crusher 35, and then stored in a storage bin 37. The grain size of the compacted material is directly compacted in a high temperature state to have a predetermined strength and size, but the grain size of the compacted material is preferably 3 to 30 mm, and the density is preferably 3.5 to 4.2 ton / m ³ . If the grain size of the compacted material is less than 3 mm, the air permeability deteriorates when charged into the melt gasifier 10, and if the particle size exceeds 30 mm, the compacted material is difficult to be manufactured and the hot strength is lowered. The compacted material temporarily stored in the storage bin 37 is supplied to the molten gasifier 10 through the high temperature equalization back pressure charging device 12 so that the compacted material can be charged into the molten gasifier 10 maintained at 3.0 to 3.5 atm under normal pressure. Charge continuously.

On the other hand, a coal filling layer is formed in the melt gasifier 10 as a heat source for melting the above compacted body. The particle size of the raw coal for forming the coal filling layer in the melt gasifier 10 should be in the form of a bulk of 10 to 50 mm, and the coal particles having such a particle size are directly charged into the melt gasifier 10, while the remaining powder of ordinary The shot goes through a particle size classification process. The coal briquette manufacturing apparatus 40 is pulverized powdered coal having a particle size of 10m or less among the powdered coals stored in the storage hopper 41 so as to have a particle size of 4mm or less, and then mixed in a mixer 43 with an appropriate amount of binder and an additive. The compacted coal briquettes are manufactured by conveying and press molding the briquette 45 into a machine. In this case, the coal briquettes have a particle diameter of 30 to 50 mm and a density of 0.8 ton / m ³ . If the particle diameter of the coal briquettes is less than 30mm, the air permeability in the molten gasifier 10 is bad, and if the particle diameter of the coal briquettes exceeds 50mm, it is difficult to manufacture the coal briquettes and there is a problem that the hot strength is lowered. The coal briquettes pressurized in this manner are transferred and stored in the storage bin 47.

The coal briquettes stored in the storage bin 47 are charged together with the lump coal into the molten gasifier 10 to form a coal packed bed. The coal briquettes charged into the melt gasifier 10 are gasified by a pyrolysis reaction in the upper part of the coal packed bed and a combustion reaction by oxygen in the lower part. The high temperature reducing coal gas generated in the molten gasifier 10 by the gasification reaction is supplied to the flow reduction furnace 20 through the reducing coal gas supply pipe (L50) connected to the rear end of the final reduction path 27 to reduce the reducing agent. And fluidizing gas. Reduction coal gas is reduced and calcined through the final reduction path 27, preliminary reduction path 26, the second preheating furnace 25, the first preheating furnace 24 in order to reduce and calcining, the first preheating Exhaust gas is discharged from the furnace 24 and the dust is removed and cooled while passing through the collecting facility 51.

Since an empty space in the form of a dome is formed on the packed layer of the melt gasifier 10, the gas flow rate may be reduced. As a result, the fine powder generated in the charged compact and the coal gas charged into the molten gasifier 10 are prevented from being released in a large amount out of the molten gasifier 10 and by directly using coal. Absorbs pressure fluctuations in the molten gasifier 10 due to irregular fluctuations in the amount of gas generated. The coal is devolatilized and gasified while descending downward in the coal packed bed, and is ultimately combusted by oxygen blown through the tuyeres below the melt gasifier 10. At this time, the combustion gas is converted into high-temperature reducing coal gas while rising the packed bed and discharged to the outside of the molten gasifier 10, and part of the pressure is applied to the molten gasifier within the range of 3.0 to 3.5 atm. It is dusted and cooled while passing through the collecting device 53 so as to remain constant. In addition, the reduced iron is finally reduced and melted by the reducing gas and combustion heat generated by coal gasification and combustion while descending the packed bed together with coal and discharged to the outside.

Cyclone 14 is installed in the melt gasifier 10 to collect dust discharged to the outside. The cyclone 14 collects exhaust gas generated in the molten gasifier 10, and the dust discharged from the molten gasifier 10 is supplied back to the molten gasifier 10, and the exhaust gas is flow-reducing furnace ( 20) is supplied as reducing coal gas. Carrier gas is injected into the rear end of the cyclone 14 to supply the dust isolated from the cyclone to the molten gasifier 10.

On the other hand, in the molten iron manufacturing apparatus 100 according to an embodiment of the present invention, the amount of reducing gas of a suitable high temperature to be supplied to the flow reduction furnace 20 in accordance with the operating conditions of the molten gasifier 10 and the change in the properties of the ordinary coal. In contrast, when the amount of high temperature reducing coal gas generated from the melt gasifier 10 is insufficient, a device for replenishing the reducing coal gas is provided. Replenishment of the amount of coal gas for reduction will be described in more detail with reference to FIG. 2.

FIG. 2 is a graph showing the relationship between the appropriate amount of high temperature reduction gas versus the amount of high temperature reduction gas generated in the melt gasification furnace, and shows a graph of the insufficient amount of high temperature reduction gas based on a reduction rate of 90%.

In accordance with the operating situation fluctuation of the melt gasifier 10 (shown in Fig. 1, below) and the change in the properties of the ordinary coal, the appropriate high temperature to be supplied to the flow reduction furnace 20 (shown in Figure 1, below) There is a case where the amount of reducing gas to the amount of high temperature reducing gas generated in the molten gasifier is insufficient. Therefore, by controlling the operating conditions of the flow reduction furnace 20, not only the reduced iron reduced through the flow reduction furnace 20, the reduction rate is reduced, but also the reduced reduction iron in the melt gasifier 10 is dissolved melt gasification The lack of heat in the furnace 10 is prevented.

In FIG. 2, curve D is a curve showing a relationship between reduction rate and gas source unit, and curves A to C show the amount of gas generated by melting gasification in terms of reduction rate versus gas source unit according to the volatile content in the coal.

For example, in the graph of FIG. 2, when the target reduction rate of the reduced iron is 90%, the amount of coal gas for reduction is 1400 Nm ³ per ton of iron ore from the curve D, whereas the amount of coal gas for reduction generated in the molten gasifier is General tannae volatile content (volatile material, VM) content of 23%, 26% and 30% of the cases, each iron ore per ton of 850Nm ^3, 950Nm ³ and with only a 1050Nm ³ iron ore per ton of each of 550Nm ^3, 450Nm ³ and 350Nm It can be seen that the reducing gas of ³ is insufficient. As described above, when the iron-containing mixture is reduced in a fluid reduction reactor in a state where the coal gas for reduction is insufficient, molten iron of desired physical properties cannot be obtained. Therefore, by replenishing the amount of reducing coal gas, the reduction rate of the desired reducing body can be obtained.

In order to replenish the coal gas for reduction, the molten iron manufacturing apparatus 100 shown in FIG. 1 is a reformed flue gas supply pipe for supplying reformed flue gas in which CO ₂ is removed by branching flue gas discharged through a multi-stage flow reduction furnace 20 ( L51). The reformer flue gas supply pipe L51 is provided with a compressor 76 and a gas reformer 77 to remove CO ₂ contained in the flue gas discharged to the first preheating furnace 24. In addition, a tar removing device 75 is provided in front of the compressor 76 to remove tar contained in the gas introduced into the compressor 76, thereby preventing condensation of tar in the compressor 76.

Referring back to FIG. 1, in the molten iron manufacturing apparatus 100, a part of the exhaust gas discharged from the first preheating furnace 24 and passing through the collecting device 51 is passed through the tar removing device 75 to provide a compressor ( After stepping up to 76), the gas reformer 77 is passed to make reformed exhaust gas and then finally supplied to the flow reduction furnace 20 through the valve V772 to compensate for the insufficient amount of coal gas for reduction. In this case, the reformed exhaust gas is mixed with the reducing coal gas and then supplied to the flow reduction furnace 20. Before supplying to the flow reduction furnace 20, by using the oxygen burner 70 installed in the reduction coal gas supply pipe (L50) to reduce the temperature of the reduced coal gas due to the mixing of the reforming exhaust gas in the flow reduction furnace 20 It is heated to the temperature necessary for the reduction of. These steps can achieve a number of beneficial effects.

First, the reformed exhaust gas supply pipe L51 is connected to the front end of the cyclone 14 to supply the reformed exhaust gas at room temperature to the cyclone 14 to prevent the cyclone 14 from overheating. Therefore, the dust discharged from the melt gasifier 10 can be efficiently collected by the cyclone 14 so as not to be scattered to the outside of the melt gasifier 10.

In addition, since the high temperature reducing coal gas discharged from the melt gasifier 10 is mixed with the reformed flue gas at room temperature, it is lower than the temperature required for supplying the flow reduction furnace 20 and thus the reduction rate of the reducing body cannot be increased to a desired level. . Therefore, by using the oxygen burner 70 to increase the reduction rate of the reducing body by heating the reducing coal gas mixed with the reformed exhaust gas by controlling the reducing coal gas to the temperature required for the reduction of the iron-containing mixture. In particular, in the case of the molten iron manufacturing apparatus 100, since the temperature of the exhaust gas passing through the flow reduction furnace 20, that is, the exhaust gas finally passed through the first preheating furnace 24 is relatively low, the exhaust gas is collected in the collecting device 51. The amount of coolant consumed during cooling is small. Therefore, the manufacturing cost is reduced.

In addition, in the case of dust and tar present in the upper portion of the melt gasifier 10, since the reducing coal gas is circulated to the reformed exhaust gas through the flow reduction furnace 20, the dust and tar can be circulated with the reducing coal gas. Sufficient paths are secured so that much is eliminated. As a result, a large amount of tar is condensed on the collecting device 51, thereby preventing the operation of the collecting device 51. In addition, simply installing the small tar removal device 75 in front of the compressor 76 can prevent the compressor 76 and the gas reformer 77 from failing due to tar condensation.

Since passing through the collection binary unit 51, the exhaust gas is the ingredient of 35% by volume of CO, 20% by volume of H _2, and 40% by volume CO _2, the CO ₂ in the gas reforming unit 77, in order to increase the reducing power It is desirable to remove. The amount of branched exhaust gas is adjusted to be 60% by volume or less of the total amount of exhaust gas discharged from the flow reduction furnace 20, so that even when the amount of reducing coal gas supplied to the flow reduction furnace 20 is insufficient, this can be sufficiently compensated. . If the amount of branched flue gas exceeds 60% by volume, the amount of reformed flue gas mixed with the reducing coal gas supplied to the flow reducing furnace 20 increases, so that the gas flow rate in the flow reducing furnace 20 is increased, and thus, iron-containing The mixture is scattered largely out of the flow reduction furnace 20. Accordingly, there is a problem that the iron-containing mixture is lost.

In addition, by adjusting the amount of reducing gas supplied to the flow reduction furnace 20 to be in the range of 1050 to 1400 Nm ³ with respect to 1 ton of iron-containing ore in the powder-reducing furnace 20, the flow reduction furnace 20 It is possible to efficiently reduce the powdered iron-ore ore supplied to). That is, when the high-temperature reducing gas is less than 1050 Nm ^{3 for} 1 ton of iron-containing ore charged in the powdered phase, reduction reaction of the iron-containing ore in powder phase is difficult to achieve, and when it exceeds 1400 Nm ³ , the reducing gas is reduced. Ore is reduced and adhered in the flow reduction furnace due to the oversupply, and it is difficult to generate flow reduction conditions.

When CO ₂ is removed using the gas reformer 77, the CO ₂ content in the reformed exhaust gas that has passed through the gas reformer 77 is preferably 3.0 vol% or less. If the CO ₂ content exceeds 3.0% by volume, the reducing power of the reformed exhaust gas is lowered, which is not suitable for use in the flow reduction furnace (20).

In addition, as shown in Figure 1, in the molten iron manufacturing apparatus 100 according to an embodiment of the present invention branched a portion of the exhaust gas passing through the collecting device 51 passes through the tar removal device 75 and the compressor After stepping up to 76 and reforming by passing through the gas reformer 77, after opening the valve V771 installed in the transport gas pipe L52, the dust isolated from the cyclone 14 is melted into the gasifier 10. It can be used as a carrier gas for charging. To this end, the transport gas pipe L52 is connected to the cyclone 14 rear end. As such, using the reformed gas as a carrier gas may not only reduce the amount of nitrogen used as the carrier gas but also improve the combustion rate.

By reforming the reformed exhaust gas from which CO ₂ has been removed, the valve V773 installed in the reducing gas resupply pipe L53 may be opened, and the reformed exhaust gas may be blown into the molten gasifier 10 during oxygen injection. Accordingly, the amount of coal briquettes may be reduced by supplying reformed exhaust gas into the melt gasifier 10, and gas distribution of a char bed may be improved.

3 is a view showing a process of circulating the reducing coal gas in the molten iron manufacturing apparatus according to an embodiment of the present invention, and shows a pipe through which the reducing coal gas is circulated in a thick solid line. do. In the case of the closed valve during the circulation of the reducing coal gas, the reducing coal gas is actually filled up to the front end of the valve.

As shown in FIG. 3, the reformed exhaust gas branched from the exhaust gas and boosted and reformed may control circulation with a valve installed in the pipe. That is, when the amount of reducing coal gas required for reduction in the flow reduction furnace 20 is insufficient, the valves (V51, V52, V27, V762, V772) in the molten iron manufacturing apparatus 100 according to an embodiment of the present invention Opening and closing the remaining valves can replenish the coal gas for reduction in the flow reduction furnace (20). The method for replenishing the reducing gas shown in FIG. 2 is merely for illustrating the present invention, and the present invention is not limited thereto.

4 is a schematic view showing a process of circulating a reducing coal gas after closing the supply of reducing coal gas from the molten gasifier 10 to the flow reduction furnace 20 in the molten iron manufacturing apparatus according to an embodiment of the present invention. As shown in Fig. 2, a pipe through which the coal gas for reduction is circulated in a thick solid line is shown. In the case of a closed valve during the circulation of the reducing coal gas, the reducing coal gas is actually filled up to the front end of the valve, but this should be illustrated.

This process corresponds to a case in which the melt gasifier 10 is tripped and thus cannot supply reducing gas to the multistage flow reduction furnace 20, in which case the total amount of exhaust gas discharged from the multistage flow reduction furnace 20 is reduced. This is bypassed through the exhaust gas bypass circulation pipe (L54) for supplying to the multi-stage flow reduction furnace 20 is supplied to the multi-stage flow reduction furnace (20).

In the melt gasifier 10, a trip may occur due to residual trouble. In this case, since no gas is generated from the molten gasifier 10, it is necessary to continuously circulate the exhaust gas so as to maintain the bubble fluidized bed in the flow reduction furnace 20 connected thereto. In this case, charging of the compacted material, the lump coal, and the coal briquettes charged into the coal filling layer of the melt gasifier 10 is stopped, and the discharge of the reducing gas from the melt gas furnace 10 is blocked to close the melt gas furnace 10. do. The valve V762 is closed to boost the exhaust gas discharged from the flow reduction path 20 to the compressor 76 while passing through the valve V51. At the same time, the valve V761 provided in the exhaust gas bypass circulation pipe L54 is opened to supply the exhaust gas to the flow reduction path 20. In this way, the exhaust gas is continuously circulated. In this process, the valves V27, V53, V771, V772, and V773 are all closed in order to prevent the exhaust gas from leaking to the molten gasifier 10 side. Therefore, the exhaust gas can be continuously circulated while preventing the exhaust gas from leaking into the melt gasifier 10. In this way it is possible to prevent the collapse of the bubble fluidized bed formed in the flow reduction path (20).

FIG. 5 is a schematic view illustrating a process of purging the flow reduction furnace 20 in the apparatus for manufacturing molten iron 100 according to an embodiment of the present invention, wherein a part of the boosted and reformed reformed exhaust gas is a flow reduction furnace The piping for purging (20) is shown by a thick solid line. In the case of the valve closed during the circulation of the reducing coal gas, the reducing coal gas is actually filled up to the front end of the valve.

If purge is required during operation, the purge reforming flue gas is supplied to the flow reduction furnace 20 through the purge coal gas supply pipe L55. As the purge is carried out as described above, general operation is continued, and a part of the reformed exhaust gas is mixed with the exhaust gas of the molten gasifier 10 through the reformed exhaust gas supply pipe L51 and supplied to the flow reduction furnace 20, and part of As in operation, it is supplied to the air vent or the dust burner of the molten gasifier 10 through the transport gas pipe L52 and the reducing gas resupply pipe L53. The flow of such reformed flue gas is shown by a thick solid line.

The multi-stage flow reduction furnace 20 includes internal devices such as built-in cyclones, standpipes, riser pipes, and dumping lines, which include reducing coal gas. There is a need to maintain the flow state so that the and iron-containing mixtures flow continuously. Therefore, it is necessary to install a purge line to prevent clogging of these internal devices. Normally, the purge is performed using nitrogen gas. However, the use of the reducing coal gas does not require the use of nitrogen gas separately, so the nitrogen consumption can be greatly reduced.

In the case of purging with nitrogen gas, since the exhaust gas discharged from the flow reduction furnace 20 is branched and reformed and circulated back to the flow reduction furnace 20, nitrogen is accumulated in the reformed exhaust gas and ultimately, the flow reduction furnace The nitrogen concentration of the total reduction coal gas supplied to (20) becomes high. As a result, when the nitrogen concentration of the inert gas exceeds 10.0% by volume of the total reduction coal gas, the ore reduction rate in the fluid reduction furnace 20 is lowered. Therefore, as described above, by using the reformed exhaust gas as the purge gas, the nitrogen content in the reducing coal gas is lowered to 10.0% by volume or less. Accordingly, it is possible to prevent the accumulation of nitrogen components in the reducing coal gas supplied to the flow reduction furnace 20.

To this end, the exhaust gas discharged through the multi-stage flow reduction furnace 20 is branched to supply reformed exhaust gas from which CO ₂ has been removed to each flow reduction furnace 20 through a coal gas supply pipe L55 for purging. Although not shown in FIG. 5, the coal gas supply pipe L55 connected to each flow reduction furnace 20 is branched again to supply reformed exhaust gas to the internal device of each flow reduction furnace 20 to purge these internal devices if necessary. Can be. In particular, it is possible to adjust the amount of reformed exhaust gas supplied for purge through the valve V24 provided in the purge coal gas supply pipe L55.

Hereinafter, in the molten iron manufacturing method according to the present invention, the operating conditions of the flow reduction furnace will be described in more detail. That is, in the present invention, considering the fact that it is very important to reduce the iron-containing mixture by using the coal gas for reduction, the optimum conditions for controlling the flow reduction reactor are derived.

6 is a graph showing the relationship between the oxidation degree and the Fe compound phase according to the temperature of the flow reduction reactor in the molten iron manufacturing apparatus according to an embodiment of the present invention, showing a stable region of the Fe compound phase for each flow reduction reactor.

Here, the oxidation degree is calculated by using the gas content of CO, CO ₂ , H ₂ , H ₂ O, etc. in the reducing gas, and means a measure of reducing gas reducing power, and (CO ₂ volume% + H ₂ O volume% ) / (defined as the volume of CO% + H ₂ volume% + CO ₂ volume% + H ₂ O volume%) × 100 (%). In FIG. 6, for convenience, 100-oxidation degree obtained by subtracting the aforementioned oxidation degree from 100 is used as the Y-axis value, which means reduction degree as an opposite concept of oxidation degree. Therefore, the reduction reaction occurs well up the Y axis, and the oxidation reaction occurs well down the Y axis.

In the molten iron manufacturing method according to an embodiment of the present invention, since the flow reduction furnace 20 (shown in Figure 1, the same below) directly using coal gas as reducing gas, other flow reduction process using the natural gas directly (FINMET It is possible to operate under relatively low spectral residence time of up to 60 minutes per gas flow unit of 1400 Nm ³ / ton and relatively lower than that of FIOR, IRON CARBIDE, etc.). Therefore, in the flow reduction process as shown in FIG. 6, the first preheating furnace in which the first step of preheating the iron-containing mixture is performed, has a second step of reheating the iron-containing mixture in the Fe ₃ O ₄ stable region. In the second preheating furnace, in the FeO stable zone, a preliminary reduction furnace in which a third stage of preliminary reduction of the preheated iron-containing mixture is carried out and the final reduction furnace in which the fourth stage of final reduction of the pre-reduced iron-containing mixture are performed in the Fe stable region It is preferred that a flow reduction is achieved. By maintaining such a region, the iron-containing mixture passes through the first preheating furnace and the second preheating furnace to minimize the amount of stabilization of the Fe ₃ O ₄ phase having a very low reduction reaction rate, and a preliminary reduction furnace having a Fe stable region formed therein. And it can be induced to achieve a sufficient reduction through the final reduction path.

As described above, in a flow reduction reactor operating at a relatively low gas source unit, it is important to control temperature and composition of reducing coal gas in each flow reduction reactor in order to secure a stable region on each Fe compound in each flow reduction reactor. .

In order to form the flow reduction conditions in the flow reduction furnace of each stage as described above, the bubble fluidized bed temperature of the first preheating furnace is 400-500 ° C., and the bubble fluidized bed temperature of the second preheating furnace is 600-700 ° C. It is preferable to make the bubble fluidized bed temperature of a reduction furnace into 700-800 degreeC, and to maintain the bubble fluidized bed temperature of a final reduction furnace at 770-850 degreeC. In addition, the composition of the reducing coal gas supplied to each fluidized bed is 45% or more in the first furnace, 35% to 50% in the second preheating furnace, and 25 in the preliminary and final reduction furnaces based on the oxidation degree. It is preferable to keep it below%.

Reduction coal gas discharged from the molten gasifier to the bubble fluidized bed of the final reduction furnace in the proper temperature and reducing coal gas composition for each flow furnace to maintain the conditions as described above the temperature is 1000 ℃ If it is too high and is supplied to the final reduction furnace as it is, the iron-containing mixture in the final reduction furnace is overheated and sticking phenomenon occurs between the ores. Therefore, it is necessary to cool the reducing coal gas supplied to the final reduction furnace. This is possible by mixing the reformed flue gas at room temperature with the reducing coal gas discharged from the molten gasifier as described above. Further, as described above, since the supply amount of the reformed exhaust gas at room temperature is adjusted by the amount of reducing gas required for the final reduction furnace, the reducing coal gas supplied to the final reduction furnace in the mixing process may be subcooled to a temperature below a proper temperature. Therefore, the reformed flue gas at room temperature is mixed with the reducing coal gas, and then oxygen is blown into the reducing coal gas to partially burn the combustion gas to maintain the temperature of the reducing coal gas at an appropriate temperature.

1, an oxygen burner 72 is installed between the second preheating furnace 25 and the preliminary reduction reactor 26, and between the preliminary reduction reactor 26 and the final reduction reactor 27. An oxygen burner 71 is provided to partially blow the oxygen into the coal gas for reduction discharged from each flow reduction furnace 20. Through this method, the oxidation degree of the reducing coal gas in the bubble fluidized bed of the preliminary reduction reactor 26 is maintained at 35% or less. In addition, the oxidation degree of the reducing gas in the bubble fluidized bed of the second preheating furnace 25 is maintained in the range of 40% to 60%. And the oxidation fluid of each flow reduction furnace 20 is adjusted by supplying the reducing coal gas discharged | emitted from the 2nd preheating furnace 25 to the bubble fluidized bed of the 1st preheating furnace 24 as it is.

Therefore, according to the present invention, as described above, when the amount of reducing coal gas is insufficient in the actual process, there are various advantages, such as not only supplementing the above, but also satisfying the operating conditions of the ideal flow reduction reactor.

Table 1 below shows the fluidized bed temperature, the reduction gas oxidation degree, and the Fe-O phase in the ore discharged from each stage of the flow reduction reactor formed in the four-stage flow reduction reactor operation according to the embodiment of the present invention. have.

In Table 1, the gas source unit is 1200 Nm ³ / t-Ore. As can be seen in Table 1, the amount of Fe ₃ O ₄ formed in the first preheating furnace is minimized by controlling the fluidized bed temperature and the reducing gas oxidation degree of each of the flow reducing reactors in the fluidizing reactor within the above-described ranges, and 2 Fe ₃ O ₄ can no longer be formed in the preheating furnace, leading to reduction of the metal Fe phase in the preliminary reducing furnace to achieve a reduction rate of 80% or more for the powdered iron ore in the final reducing furnace. have.

The apparatus for manufacturing molten iron according to an embodiment of the present invention described above has an advantage of being suitable for use in connection with an integrated steelmaking apparatus while the entire apparatus is compact while directly using powdery or bulky coal and powdery iron-containing ore. Therefore, by applying the molten iron manufacturing apparatus according to an embodiment of the present invention to a mini mill process, which is an integrated steelmaking process, it is possible to directly produce hot rolled steel sheet from powdery or bulky coal and powdery iron-containing ore. Hereinafter will be described in detail with respect to the integrated steel manufacturing apparatus using a molten iron manufacturing apparatus according to an embodiment of the present invention. Examples of such integrated steel making apparatus are merely to illustrate the present invention, but the present invention is not limited thereto.

FIG. 7 is a view showing an example of the integrated steel making apparatus 1000 using the apparatus for manufacturing molten iron 100 according to an embodiment of the present invention, which directly manufactures a hot rolled steel sheet from powdery or bulky coal and powdery iron-containing ore. The integrated steel making apparatus 1000 is schematically shown. The apparatus for manufacturing molten iron shown in FIG. 7 has the same structure as that of the apparatus for manufacturing molten iron according to an embodiment of the present invention described above, and thus, a detailed description thereof is omitted for convenience. The description mainly focuses on the parts.

The integrated steelmaking apparatus shown in FIG. 7 is connected to the molten iron manufacturing apparatus 100 and the molten iron manufacturing apparatus 100 to remove the impurities of molten iron and decarburize the steelmaking apparatus 200 and the steelmaking apparatus 200 to manufacture molten steel. The thin slab casting machine 300 is connected to the thin slab casting machine 300 and continuously connected to the thin slab casting machine 300 to hot-roll the thin slab discharged therefrom to manufacture a hot rolled steel sheet. Rolling mill 400. In addition, other necessary devices may be included.                     

7 illustrates an example of the steelmaking process using the above-described device in detail. The steelmaking apparatus 200 which performs a steelmaking process is connected to the iron preliminary processing apparatus 61 which removes phosphorus and sulfur in molten iron, and the iron preliminary processing apparatus 61, and the decarburization apparatus which removes carbon and impurities in molten iron from this ( 64 and a ladle 67 connected to the decarburization device 64 to secondary refine the molten iron therefrom to produce molten steel.

The molten iron discharged from the molten gas furnace 10 is periodically discharged to the molten iron preliminary processing apparatus 61 having a refractory container and transferred to a lower process, and the flux in the molten iron in the molten iron preliminary processing apparatus 61 during transfer. The sulfur component in molten iron is adjusted to 0.006% or less by performing a molten iron preliminary treatment which blows a phosphorus desorbent and removes the sulfur and phosphorus component in molten iron. In the preliminary treatment of molten iron, CaO or CaCO ₃ is preferably used as the desorbing agent.

In addition, the molten iron in the molten iron preliminary processing device 61 after the molten iron preliminary treatment 61 is discharged to the decarburization unit 64 of the converter type, the molten slag generated in the molten iron preliminary process during the discharge process is suspended in the molten iron decarburization apparatus It is preferable not to mix in (64). After the molten iron is charged into the decarburization device 64, oxygen is blown from the upper portion at a high speed to perform oxidative refining, and impurities such as carbon, silicon, phosphorus, and manganese dissolved in the molten iron are oxidized and removed into the molten steel during the oxidation refining. The oxidized impurities are dissolved and separated from the molten steel into molten slag formed on the molten steel by CaO, CaF ₂ and dolomite, which are introduced into the converter. After the oxidation refining is completed, the molten steel is discharged from the decarburization apparatus 64 to the ladle (67), which is a refractory container, and is transferred to a later process. Through such a steelmaking process, the carbon content in the molten iron is adjusted to 2.0 wt% or less.

Molten steel undergoes the secondary refining process in the ladle 67, heating by an electric arc formed on the molten steel by the high voltage transmitted through the electrode, stirring by inert gas blown from the lower ladle 67, etc. Through the uniformity of the temperature and component distribution in the molten steel and floating separation of non-metallic inclusions in the molten steel, and if necessary, Ca-Si powder may be blown into the molten steel to actively remove traces of sulfur present in the molten steel. In addition, after the above-described process is completed, the vacuum chamber is connected to the upper portion of the refractory vessel to form a vacuum on the upper side of the molten steel through the degassing process to remove the gas remaining in the molten steel and gas components such as N ₂ , H ₂ To improve. In the degassing process, it is preferable to burn the gas component discharged by blowing oxygen to prevent the molten steel temperature decrease as the heat of combustion.

After the above-described secondary refining process, the ladle 67 is transferred to the thin slab casting machine 300. The molten steel is discharged from the ladle 67 to the tundish 71 above the thin slab casting machine 300, and the molten steel is supplied from the tundish 71 into the thin slab casting machine 73 to have a thickness of 40 to 100 mm. Cast directly to thin slabs. The cast thin slab is reduced in the form of a bar having a thickness of 20 to 30 mm through a rough rolling mill 75 directly connected to the thin slab casting machine 73, and after being heated in the heater 77, the winding machine 79. It is rolled up and piled up. The above-described thin slabs are easily broken when the thickness is less than 40 mm, and when the thickness of the thin slabs is greater than 100 mm, the roughing mill 75 may be pressed when pressed with the roughing mill 75.

The rolled-up bar is released again to remove the rust generated on the bar surface while passing through the rust remover 83, and then transferred to the final rolling mill 85 to be rolled into a hot rolled steel sheet having a thickness of 0.8 to 2.0 mm and cooled in the cooler 87. Next, it is wound up by the winding machine 89 by the final hot rolled steel sheet. Hot rolled steel sheets with a thickness of 0.8 to 2.0 mm are suitable for use in demand.

In the integrated steel making apparatus 1000 using the apparatus for manufacturing molten iron 100 according to an embodiment of the present invention, a hot rolled steel sheet is directly made by using powdered or bulky ordinary coal and powdered iron ore through the above-described process. There is an advantage to manufacture. Therefore, the hot rolled steel sheet may be manufactured using a compact facility as well as not limited to the raw materials in the manufacture of molten iron.

8 is a view showing another example of the integrated steel making apparatus 2000 using the molten iron manufacturing apparatus 100 according to an embodiment of the present invention, another multi-stage flow reduction path 90 and another compacted material manufacturing apparatus A process of supplying reduced iron to the decarburization device 64, which is one of the steelmaking devices 200, by installing 35 is shown. Since the integrated steelmaking apparatus 2000 shown in FIG. 8 has the same structure as the integrated steelmaking apparatus shown in FIG. 7 except for a part, the description of the same parts will be omitted for convenience, and the other parts will be described in detail. .

In addition, in the integrated steel making apparatus 2000 described below, the flow reduction furnace 20 connected to the melt gasifier 10 described above is referred to as a first flow reduction reactor for convenience, and another multistage flow reduction reactor 90 is provided. Is called the second flow reduction path. In addition, the compacted material manufacturing apparatus 30 connected to the 1st flow reduction furnace 20 and the rear end is called the 1st compacted material manufacturing apparatus, and is another compacted material provided in the rear end of the 2nd fluidized-reduction path 90 separately. The manufacturing apparatus 35 is called 2nd compacted body manufacturing apparatus.

As shown in FIG. 8, the integrated iron making apparatus 2000 includes a second flow reduction path 90 and a second compacted material manufacturing apparatus 35. The second flow reduction reactor (90) is a facility for receiving the powdered iron ore from the iron-containing ore hopper (91) and reducing it to reduced iron. The preheating furnace (93), the preliminary reduction reactor (95), and the final reduction furnace ( It consists of a three-stage flow reduction reactor (97), and a bubble fluidized bed is formed in each flow reduction reactor.

In the second flow reduction furnace (90), the preheating furnace (93) preheats the powdered iron ore at 600 to 700 ° C, and the preliminary reduction furnace (95) connected to the preheating furnace (93) is preheated iron. The ore is preliminarily reduced to 700 to 800 ° C., and the final reduction furnace 97 is connected to the preliminary reduction furnace 95 to finally reduce the iron-containing ore preliminarily reduced to 770 to 850 ° C.

The second flow reduction path 90 is dried and mixed while sequentially circulating a portion of the exhaust gas discharged from the first flow reduction furnace 20 from the final reduction path 97 through a separate reduction gas circulation tube and having a particle diameter of 8 mm or less Iron-containing ore is reduced to 92% or more to convert to reduced iron. 8 shows the second flow reduction path in three stages, this is merely to illustrate the present invention and various stages of flow reduction paths may be used.

In addition, the second compacted material manufacturing apparatus 35 once stores the high-temperature reduced iron that passed through the final reduction path 97 in the charging hopper 36 and then passes between the pair of rolls 37 in a high temperature state. It is mechanically press-molded and compacted, and then crushed by the crusher 38 and stored in the compacted material supply hopper 39.

The amount of reducing coal gas supplied to the second flow reduction path 90 is the amount of re-supply to itself among the amount of exhaust gas discharged from the bubble fluidized bed in each stage of the first flow reduction furnace 20 used to manufacture molten iron. 40 vol% or more is preferred except for (60 vol% or less). On the other hand, in the step of supplying a portion of the exhaust gas discharged from the first flow reduction furnace 20 to the second flow reduction path 90, tar is removed from the exhaust gas by the tar removal device 75. The exhaust gas from which tar is removed is boosted by a booster 76, and then a reformed exhaust gas reformed of CO ₂ is supplied using a gas reformer 77. The amount of CO _{2 in the} reformed flue gas is preferably 3.0% by volume or less. The reducing coal gas which has passed through the second flow reduction path 90 is discharged to the outside after dust removal and cooling through the collecting device 55.

Although not shown in FIG. 8, the oxygen is blown into the reformed exhaust gas and the reformed exhaust gas is partially burned to increase the heat of combustion, but the temperature after heating is preferably about 800 to 850 ° C.

Since the reduced iron produced as described above uses only iron-containing ore and purified reducing gas, more than 90% is made of pure iron and has a very low sulfur content. Cleanliness can be further improved.

Hereinafter, the present invention will be described in more detail with reference to experimental examples. These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.                     

Experimental Example

Through the molten iron manufacturing apparatus according to an embodiment of the present invention described above to produce molten iron and slag.

In the experimental example according to an embodiment of the present invention, in the case of a melt gasifier, the furnace internal pressure was maintained at 3.2 atm, and the amount of oxygen supplied for coal combustion in the melt gasifier was adjusted to 550 Nm ³ per ton of molten iron. In addition, the amount of spectroscopy and subsidiary materials charged to the fluid reduction reactor was quantitatively supplied at 1.5 tons and 0.35 tons, respectively, based on the production of 1 ton of molten iron, and the amount of coal supplied to the melt gasifier was 0.9 to the production of 1 ton of molten iron. Quantitative supply of 1.0 ton. Under the above operating conditions, the production capacity of the apparatus for manufacturing molten iron was 85 tons per hour based on molten iron.

The composition of molten iron and slag tapping from the molten gasifier according to the result of the experiment according to the embodiment of the present invention described above is as follows. Table 2 shows the composition of molten iron according to the embodiment of the present invention, Table 3 shows the composition of the slag according to the embodiment of the present invention.

As shown in Table 2, the temperature of the molten iron produced through the experimental example according to the present invention was about 1500 ℃, the content of impurities other than iron in the molten iron was as described above.

As shown in Table 3, the slag produced through the experimental example according to the present invention had a temperature of about 1520 ° C., and a basicity of 1.15.

As can be seen from Table 2, the molten iron according to the present invention is not only suitable for the temperature of about 1500 ℃ but also has a relatively small content of Si, P and S, satisfies the general steel quality standards for steelmaking. have. In addition, as shown in Table 3, since the slag is not only suitable for the temperature of about 1520 ℃ but also the basicity of about 1.15, which is a measure of the quality of slag, the molten iron manufacturing method according to an embodiment of the present invention is a conventional blast furnace method and Despite the use of powdery or bulky coal and powdery iron ore, the quality of molten iron was almost the same.

As described above, according to the present invention, the method for manufacturing molten iron of the present invention can continuously produce high-quality molten iron that satisfies the quality criteria of molten iron for steelmaking by directly using powdery or bulky coal and powdery iron-containing ore. Therefore, it is possible to replace the blast furnace method used in the integrated steel mill. Therefore, it is possible to reconsider the economic feasibility of the integrated steelworks by using low-cost raw materials and thus eliminating the sintering and coke processes, and block generation of pollutants emitted from the sintering and coke processes.

In addition, the apparatus for manufacturing molten iron of the present invention branches off the exhaust gas discharged from the flow reduction reactor and supplies the reformed flue gas reformed therein to the flow reduction reactor, so that it can be supplemented when there is a shortage of reducing coal gas, thereby ensuring operational flexibility. Can be.

In this case, since the cooled reformed exhaust gas of normal temperature can be supplied to the cyclone front end, overheating of the cyclone can be prevented.

Further, according to the present invention, by using the exhaust gas from the fluid reduction as a carrier gas, the amount of nitrogen used as the carrier gas can be reduced.

Since the reformed exhaust gas produced through the present invention can be blown together with oxygen into the molten gasifier again, not only the coal use cost can be reduced but also the gas flow distribution of the car bed can be improved.

It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the following claims.

Claims (42)

Mixing and drying the powdery iron-containing ore and secondary raw materials to produce an iron-containing mixture, Converting the iron-containing mixture into a reducing body by reducing and calcining while passing through a multi-stage flow reduction reactor connected to each other; Preparing a compacted material by high temperature compacting the reducing body, As a heat source for melting the compacted material, charging coal and coal briquettes formed by compacting powdered ordinary coal into a melt gasifier to form a coal-filled layer, Preparing molten iron by charging the compacted material into a molten gasifier connected to the multi-stage flow reduction reactor and injecting oxygen into the molten gasifier; Supplying the reducing coal gas discharged from the melt gasifier to the flow reduction reactor, Branching the exhaust gas discharged through the multi-stage flow reduction path to remove CO ₂ ; Mixing the reformed exhaust gas from which the CO ₂ is removed with the reducing coal gas discharged from the molten gasifier, and Molten iron comprising the step of raising the temperature of the reducing coal gas mixed with the reforming flue gas before supplying it to the flow reducing reactor, and controlling the reducing coal gas at a temperature necessary for reducing the iron-containing mixture in the flow reducing reactor. Manufacturing method. delete The method of claim 1, The method of manufacturing molten iron for heating the reformed exhaust gas by heating with an oxygen burner in the step of raising the temperature of the reducing coal gas mixed with the reformed exhaust gas before supplying the flow reduction reactor. The method of claim 1, In the step of removing the CO ₂ by branching the exhaust gas discharged from the flow reduction path, the branched exhaust gas amount is 60% by volume or less of the total amount of exhaust gas discharged from the flow reduction path. The method of claim 1, ] The method of maintaining the extent of the modification on the iron-containing ore minutes the amount of exhaust gas per ton of 1050Nm ³ to 1400Nm ^3. The method of claim 1, In the step of mixing the reformed exhaust gas from which the CO ₂ is removed with the reducing coal gas discharged from the melting gasifier, the content of CO ₂ in the reformed exhaust gas is 3.0 vol% or less. The method of claim 1, The method of manufacturing molten iron for boosting the branched exhaust gas in the step of removing CO ₂ by branching the exhaust gas discharged from the flow reduction path. The method of claim 1, And before removing the CO ₂ by branching the exhaust gas discharged from the flow reduction path, branching the exhaust gas discharged through the multi-stage flow reduction path to remove tar. The method of claim 1, In the step of mixing the reformed flue gas from which the CO ₂ is removed with the reducing coal gas discharged from the molten gasifier, a shear of a cyclone charging the dust discharged from the molten gasifier into the molten gasifier. Method of manufacturing molten iron mixed in 10. The method of claim 9, And a reformed exhaust gas from which the CO ₂ has been removed, and used as a carrier gas for charging the dust isolated from the cyclone into the molten gasifier. The method of claim 1, And bypassing the entire exhaust gas discharged from the multi-stage flow reduction path at the time of closing the molten gasification furnace or starting the molten gasification furnace, and supplying the exhaust gas to the multistage flow reduction path. The method of claim 1, Branching the exhaust gas discharged through the multi-stage flow reduction path to remove CO ₂ , and Branching the reformed exhaust gas from which the CO ₂ has been removed and supplying it to each of the flow reduction reactors to purge the flow reduction reactors. The molten iron manufacturing method further comprising. The method of claim 12, The nitrogen content in the reducing coal gas is 10.0% by volume or less manufacturing method. The method of claim 1, Branching the exhaust gas discharged through the multi-stage flow reduction path to remove CO ₂ , and Branching the reformed exhaust gas from which the CO ₂ is removed and blowing the oxygen together into the molten gasifier; The molten iron manufacturing method further comprising. The method of claim 1, In the step of converting the iron-containing mixture to a reducing body, A first step of preheating the iron-containing mixture to 400 to 500 ° C., A second step of reheating the preheated iron-containing mixture to 600 to 700 ° C., A third step of preliminarily reducing the reheated iron-containing mixture to 700 to 800 ° C., and A fourth step of finally reducing the pre-reduced iron-containing mixture to 770-850 ° C. Iron manufacturing method comprising a. The method of claim 15, The oxidation degree in the first step and the second step is 25% or less, The degree of oxidation in the third step is 35 to 50%, Oxidation degree in the fourth step is 45% or more manufacturing method. Here, the oxidation degree is (CO ₂ vol% + H ₂ O vol%) / (CO vol% + H ₂ vol% + CO ₂ vol% + with respect to CO, CO ₂ , H ₂ O and H ₂ gases in the reducing gas H ₂ O volume%) × 100%. The method of claim 15, The second step and the third step, the molten iron manufacturing method comprising the step of blowing oxygen. The method of claim 1, In the step of producing the compacted material, molten iron manufacturing method for high temperature compacted so that the particle size of the compacted material is 3mm to 30mm. The method of claim 1, In the step of forming the coal filling layer, the molten iron manufacturing method for manufacturing so that the particle diameter of the coal briquettes 30mm to 50mm. Manufacturing molten iron by the molten iron manufacturing method according to claim 1, Removing impurities and decarburizing the molten iron to produce molten steel; Continuously casting the molten steel into a thin slab, and Hot rolling the thin slab to produce a hot rolled steel sheet Integrated steelmaking method comprising a. 21. The method of claim 20, In the continuous casting of the molten steel into a thin slab, Integrated steelmaking method of continuously casting the molten steel to a thin slab of 40mm to 100mm thickness. 21. The method of claim 20, In the step of manufacturing the hot rolled steel sheet, Integrated steelmaking method for producing the hot rolled steel sheet to a thickness of 0.8mm to 2.0mm. 21. The method of claim 20, The step of manufacturing the molten steel, A preliminary treatment step for removing phosphorus and sulfur in the molten iron, Blowing oxygen into the molten iron to remove carbon and impurities in the molten iron; and Preparing molten steel by secondary refining of the molten iron to remove impurities and dissolved gases; Integrated steelmaking method comprising a. 24. The method of claim 23, Converting another powdered iron ore into reduced iron while passing through another multistage flow reduction reactor connected in sequence; and Manufacturing a reduced iron compacted material by high temperature compacting the reduced iron More, In the step of removing carbon and impurities in the molten iron, the reduced iron compacted material and the molten iron is mixed to remove carbon and impurities. The method of claim 24, The step of converting the iron powder ore of another powder to reduced iron, Preheating the other powdered iron ore to 600-700 ° C., Preliminarily reducing the preheated powdered iron ore to 700 to 800 ° C., and Converting the pre-reduced powdered iron ore into reduced iron at the final reduction to 770-850 ° C. Integrated steelmaking method comprising a. Multi-stage flow reduction furnace for converting mixed or dried powdered iron ore and by-products into reducing bodies A compacted material manufacturing apparatus connected to the multi-stage flow reduction furnace to produce a compacted material by high temperature compaction of the reducing body, Coal briquette manufacturing apparatus which manufactures the coal briquette which hardens powdered general coal as a heat source which melt | dissolves the said compacted body, A coal gasification furnace which charges the coal briquettes and the coal briquettes from the coal briquette manufacturing apparatus to form a coal packed layer therein, charges the reducing body from the compacted body production apparatus, and blows oxygen into the molten gas to produce molten iron. , And Reduction coal gas supply pipe for supplying the reducing coal gas discharged from the melt gasifier to the flow reduction reactor, A reformed exhaust gas supply pipe for branching exhaust gas discharged through the multi-stage flow reduction path to supply reformed exhaust gas from which CO ₂ is removed; And an oxygen burner installed in the reducing coal gas supply pipe and configured to heat up the reducing coal gas in which the reformed exhaust gas is mixed to the flow reduction reactor. delete The method of claim 26, The reformed exhaust gas supply pipe is a molten iron manufacturing apparatus having a gas reforming device for removing the CO ₂ from the exhaust gas branched by passing through the multi-stage flow reduction path. The method of claim 26, The reformed exhaust gas supply pipe is a molten iron manufacturing apparatus having a tar removal device for removing tar from the exhaust gas branched by passing through the multi-stage flow reduction path. 30. The method of claim 29, The reformed exhaust gas supply pipe is provided with a compressor for compressing the exhaust gas is discharged through the multi-stage flow reduction path branched, the tar removing device is provided in front of the compressor. The method of claim 26, And a cyclone for charging the dust discharged from the molten gasifier into the molten gasifier in the molten gasifier, and connecting the reformed exhaust gas supply pipe to the front end of the cyclone. The method of claim 31, wherein And a conveying gas pipe connected to the rear end of the cyclone for branching the reformed exhaust gas from which the CO ₂ has been removed and injecting the dust isolated from the cyclone as a conveying gas charged into the molten gasifier. The method of claim 26, The multi-stage flow reduction path, First preheating to preheat the iron-containing mixture to 400 ~ 500 ℃, A second preheater connected to the first preheater to reheat the preheated iron-containing mixture to 600 to 700 ° C, A preliminary reduction furnace connected to the second preheating furnace to preliminarily reduce the reheated iron-containing mixture to 700 to 800 ° C, and Final reduction furnace connected to the preliminary reduction furnace for the final reduction of the pre-reduced iron-containing mixture to 770 ~ 850 ℃ Iron manufacturing apparatus comprising a. 34. The method of claim 33, An oxygen burner is installed between the second preheating furnace and the preliminary reduction reactor, and between the preliminary reduction reactor and the final reduction furnace to heat the coal gas for reduction and supply the gas to the second preheating furnace and the preliminary reduction reactor, respectively. Molten iron manufacturing apparatus. 34. The method of claim 33, The apparatus for producing molten iron, wherein the reducing coal gas supply pipe is connected to the final reduction furnace. The method of claim 26, And a purge coal gas supply pipe for branching the reformed exhaust gas from which the CO ₂ has been removed, and supplying each of the flow reduction furnaces to purge the flow reduction reactors. The method of claim 26, And an exhaust gas bypass circulation pipe connected to the flow reduction path to supply the entire exhaust gas discharged from the flow reduction path to the flow reduction path of the multi-stage. The method of claim 26, And a coal gas resupply pipe for branching the reformed exhaust gas from which the CO ₂ has been removed to blow the oxygen gas into the molten gasifier. Device for manufacturing molten iron according to claim 26, A steelmaking apparatus connected to the molten iron manufacturing apparatus for removing impurities from the molten iron and decarburizing to produce molten steel; A thin slab casting machine connected to the steelmaking apparatus to continuously cast molten steel from the steelmaking apparatus into thin slabs, and Hot rolling mill connected to the thin slab casting machine to hot roll the thin slab discharged from the thin slab casting machine to produce a hot rolled sheet Integrated steelmaking apparatus comprising a. 40. The method of claim 39, The steelmaking apparatus, A preliminary apparatus for treating molten iron which is connected to the apparatus for manufacturing molten iron and removes phosphorus and sulfur in the molten iron discharged from the molten iron manufacturing apparatus; A decarburization apparatus connected to the molten iron preliminary processing apparatus for removing carbon and impurities in the molten iron discharged to the molten iron preliminary processing apparatus, and Ladle connected to the decarburization device to produce molten steel by refining molten iron discharged from the decarburization device secondly Integrated steelmaking apparatus comprising a. The method of claim 40, Another multistage flow reduction reactor for branching the reformed exhaust gas from which the CO ₂ is removed to convert another powdery iron ore into a reducing body, and Another compacted body manufacturing apparatus connected to the another multi-stage flow reduction furnace to produce a reduced iron compacted material by high temperature compacted the reducing body More, The another compacted material manufacturing apparatus is an integrated iron manufacturing apparatus for supplying the reduced iron compacted material to the decarburization apparatus. The method of claim 41, wherein Another multi-stage flow reduction path, Preheating to preheat the other powdered iron ore at 600 ~ 700 ℃, A preliminary reduction furnace connected to the preheating furnace to preliminarily reduce the preheated iron-containing ore to 700 to 800 ° C, and Final reduction furnace which is connected to the preliminary reduction furnace for the final reduction of the pre-reduced powdered iron ore to 770 ~ 850 ℃ Integrated steelmaking apparatus comprising a.

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