KR101620757B1 - Apparatus for Manufacturing Molten Iron and Method for Manufacturing Molten Iron Using the Apparatus - Google Patents

Abstract

The present invention relates to an apparatus to manufacture molten iron and a method to manufacture molten iron using the same comprising: a direct reduction iron (DRI) with at least a metal ratio of 80%; more than one type of reducing gas selected from a group selected from a group composed of finex off gas (FOG), blast furnace gas (BFG), and coke oven gas (COG); melting furnace exhaust gas; and a supply part which introduces oxygen to a melter gasifier. Accordingly, the present invention is able to be used to manufacture molten iron without an additional pellet process and/or briquette process by supplying ultrafine DRI which is manufactured using ferruginous byproducts together with reducing gas and oxygen to the melter gasifier.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten iron manufacturing apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire manufacturing apparatus and a wire manufacturing method using the same.

In general, iron and steel by-products produced in steel mills include iron sludge and steel dust. Some of these seasonal slag and steel dusts are being reused as separate products, but most of them are being abandoned as industrial waste, and it takes a lot of budget to deal with them. In particular, as the blast furnace has recently become larger and the production capacity of steelmakers has increased, the production of byproducts such as iron ore is also increasing.

However, since the iron sludge contains a large amount of water and the iron dust is mainly present as small powder fine particles, it is difficult to recycle the steel dust alone.

As an alternative thereto, Patent Documents 1 and 2 propose a method of recycling the steel dust and steel sludge into a melting furnace through pretreatment of assembling the iron dust and steel sludge in the form of a pellet.

However, the dust and sludge used in the above-mentioned proposal have a problem in that the slag volume can be increased and the reduction ratio is increased because the gangue ingredient is contained in a large amount. In addition, the process is complicated because it has to undergo a pretreatment process, and when it is charged into a melting furnace in the form of pellets, the use of the furnace is limited because it acts as an obstacle to the gas flow in the furnace.

In addition, as another method utilizing the iron sludge and iron dust, there has been proposed a technique of manufacturing and utilizing a direct reduction iron (DRI) having an iron content of 90% to 95%.

However, since the DRI is in a powder state having a size of several millimeters or less, when it is put into a melting furnace as it is, the reduction rate of the reducing furnace is lowered and the product is easily oxidized by reacting with water. It has disadvantages. Therefore, it has been proposed to utilize it in the hot briquetted iron (HBI) form by briquetting in the hot and then in the melting furnace to produce the molten iron.

However, in the case of passing through the single light treatment, that is, the briquetting process, there is a problem that the entire process becomes complicated because additional steps such as pulverization, screening, mixing, and molding are required. Since the binder such as bentonite, molasses, and plastics must be used in such a process, the reduced iron obtained after the heat treatment contains impurities such as Si generated from the binder used in the briquetting process, resulting in poor purity of the molten iron There is also a problem.

Therefore, there is a need to develop a technology capable of utilizing the direct reduced iron produced by using the by-product of iron ore without using a separate briquetting process and / or a pellet process in the production of a molten iron.

Korean Patent Publication No. 2002-0049889 Korean Patent Publication No. 2003-0055357

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a DRI of DRI produced by using a by-product of iron and iron, together with a reducing gas and oxygen of a specific kind, into a melting furnace, And a method for manufacturing a molten iron using the same.

In one aspect, the present invention provides a direct reduction iron (DRI) having a metalization rate of 80% or more; At least one reducing gas selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas; And a supply unit for introducing oxygen into the melting furnace.

In another aspect, the present invention provides a direct reduction iron (DRI) having a metallization ratio of 80% or more; At least one reducing gas selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas; And introducing oxygen into the melting furnace.

In addition, the solution of the above-mentioned problems does not list all the features of the present invention. The various features of the present invention and the advantages and effects thereof will be more fully understood by reference to the following specific embodiments.

According to the apparatus for recycling iron and iron by-product according to the present invention, the direct reduced iron having a high economic value added, which is produced by using the iron and iron by-products generated in a large amount in the iron making process, is supplied to the melting furnace together with the reducing gas and oxygen of a certain kind, It can be directly utilized without the process and / or the pellet process, so that the production process can be simplified and the productivity of the charcoal can be improved remarkably.

In addition, when a part of the charged iron ore is replaced with the directly reduced iron of the minute iron produced by using the above-mentioned iron-by-product, the reduction gas ratio can be drastically reduced in a part of the blast furnace.

Further, according to the method of manufacturing a molten iron according to the present invention, since a large amount of by-products generated in a steelmaking process can be utilized at low cost in a steelmaking process, economical efficiency can be remarkably improved and therefore, Is very useful value.

Fig. 1 schematically shows an example of a molten iron manufacturing apparatus according to the present invention.
Fig. 2 is a schematic view showing a reaction in a triple-tube burner included in a wire manufacturing apparatus according to the present invention.
Fig. 3 (a) shows an example of the triple-tube burner.
3 (b) shows another example of the triple-tube burner.
Fig. 4 (a) shows the measurement results of the melting temperature of the process according to Example 1. Fig.
Fig. 4 (b) shows the results of melt temperature measurement of the process according to Comparative Example 1. Fig.
Fig. 4 (c) shows the melt temperature measurement result of the process according to Comparative Example 2. Fig.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are also provided to more fully describe the present invention to those skilled in the art.

The inventors of the present invention have conducted studies to develop a technique for making DRI having a size of a few mm or less manufactured by using iron and iron byproducts directly in the production of molten iron without a briquetting process and / or a pellet process. As a result, (BFG), blast furnace gas (BFG), coke oven gas (COG), and melting furnace exhaust gas are used as the exhaust gas purifying catalyst The present invention has been accomplished based on the finding that the above objects can be achieved when a triple-tube burner is introduced into a melting furnace together with at least one reducing gas and oxygen.

More particularly, the present invention relates to a method for manufacturing a molten iron, comprising: direct reduction iron (DRI) having a metallization ratio of 80% or more; At least one reducing gas selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas; And a supply part for introducing oxygen into the melting furnace.

For the sake of understanding, FIG. 1 shows an example of the apparatus for manufacturing a molten iron according to the present invention.

Referring to FIG. 1, the apparatus for producing molten iron according to the present invention includes a direct reduction iron (DRI) 2 having a metalization rate of 80% or more in each nozzle of a burner 30 having a triple pipe structure as a supply part. At least one reducing gas (3) selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas; And oxygen (1) into the melting furnace (40).

At this time, the direct reduced iron, DRI (2) is manufactured using iron sludge and steel dust contained in the by-product of iron and iron, and the iron content may be 90% to 95%. The direct reduced iron may be selected to have a particle diameter of 100 탆 or less through a grid disposed under the bins 20 into which the direct reduced iron is inserted, and may be used in the present invention. At this time, the particle diameter of the selected direct reduced iron may be about 10 탆 to 100 탆 or about 10 탆 to 80 탆, and it is a component in powder form.

In the present invention, the DRI (2) can be produced by a method well known in the art, and is not particularly limited. For example, iron oxide sludge and steel dust, which are by-products of the steelmaking process, And may be one produced by subjecting a high-iron-iron by-product to a reduction reaction with a complex reducing gas using a by-product gas.

Particularly, in the present invention, it is preferable to use those having a metallization ratio of 80% or more in the DRI. When the metallization ratio is less than 80%, the reduction gas ratio is increased. Therefore, even if the DRI manufactured by using the by-product of iron and iron is utilized, the economical efficiency is significantly lowered.

More specifically, the DRI 2 is directly injected into the bin 20, and a particle having a particle diameter of 100 탆 or less is selected by using a grid including a vibration device, and then flows out to the melting furnace 40). That is, according to the present invention, the DRI (2) having a metallization ratio of 80% or more is directly used in the chartering apparatus without being subjected to a separate briquetting process and / or a pellet process. In this case, the reduction ratio can be drastically reduced, the high-output operation is easy, and the core can be activated.

The DRI 2 is separated from the gas 4 generated in the melting furnace through the hot cyclone 10 and then separated through a grid disposed under the hot cyclone 10 to produce a dust having a particle size of 100 μm or less (5). At this time, the particle diameter of the selected dust may be more specifically, for example, about 10 탆 to 100 탆 or about 10 탆 to 80 탆.

As shown in FIG. 1, the gas 4 generated in the melting furnace may include a part of the dust 5 scattered in the melting furnace 40. As described above, the gas 4 generated in the melting furnace is separated into the reducing gas 3 and the dust 5 in the hot cyclone 10, and the reducing gas 3 flows out to one end of the hot cyclone 10 And flows into the melting furnace 40 through the triple pipe burner 30. At this time, the dust 5 flows out to the other end of the hot cyclone 10 and then flows into the bin 20 and mixed with the DRI. At this time, dust (5) introduced into the bin (20) is arranged at a lower portion of the bin (20) and is selected to have a particle diameter of 100 탆 or less by using a grid including a vibration device. And flows into the melting furnace 40 through the triple-burner 30.

Further, the content ratio of the DRI (2) and the dust (5) in the mixture may be from 10: 0 to 5: 5, and more specifically from 7: 3 to 5: 5. The higher the content of the dust 5, the lower the temperature of the upper part of the melting furnace. When the dust 5 content is larger than that of the DRI 2, the friction between the dust particles and the pipe surface of the triple- There is a problem that the pipe is clogged with dust particles. In this case, it may be difficult to inject oxygen into the melting furnace, which causes difficulty in controlling the temperature of the upper portion of the melting furnace during operation. Therefore, when dust is mixed with DRI, it is preferable that the content of dust 5 is less than DRI (2).

On the other hand, the DRI 2 or the mixture 2 of DRI and dust can be blown into the fusion furnace through the triple tube burner by the methane (CH ₄ ) 6 in the horizontal tube 50. When the mixture of DRI or DRI and dust is blown into the melting furnace 40 through the methane load as described above, the cooling effect can be expected by the thermal decomposition of methane, the cooling water can be prevented from flowing into the furnace, It is very advantageous to prevent the quality of the reducing gas from falling.

Further, it is preferable that the dust 5 includes carbon. At this time, since the carbon can be used as a heat source, it is only required to be contained in the dust 5, and the content thereof is not particularly limited. For example, the amount of carbon contained in the dust 5 may be about 10 wt% to 35 wt%, but is not limited thereto.

The reducing gas 3 means a gas in which the dust 5 is separated from the gas 4 generated in the melting furnace 40 through the hot cyclone 10. The reducing gas 3 may be CO and / H ₂ is preferably 70% or more of the total gas. At this time, CO gas because it is faster than the carburizing reaction rate of the carbon source DRI with the carburizing reaction rate is solid at a temperature not higher than 1100 ℃, reduction of the DRI and CO exothermic reaction the content of iron by-product gas of CO gas H ₂ It is preferable to occupy a larger proportion than the content of the gas. 2, the FeO in the DRI and the dust is reduced by the reduction reaction of the reducing gas with the main component of the reducing gas, that is, CO and H ₂ which are reducing gases, and / Since the sintering effect generates agglomeration, the reduced Fe particles gradually become larger. The carburizing reaction of the carbon particles generated from the enlarged Fe particles and the CO gas lowers the melting temperature of the product. As described above, when the melting temperature is lowered, the reduction gas reduction effect is remarkably improved.

Meanwhile, the reducing gas is selected from the group consisting of, for example, FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas One or more, or a mixture of two or more, but is not limited thereto.

On the other hand, the separation efficiency of the hot cyclone 10 is preferably 80% or more. That is, it is preferable that the reducing gas (3) is one in which the dust (5) is separated from the gas (4) generated in the melting furnace by 80% or more. If the separation efficiency of the dust 5 is less than 80%, impurities are contained in the reducing gas 3, and when the reducing gas is recycled and re-blown through the dust burner into the melting furnace, mechanical abrasion of the equipment is caused, The flow of the gas is interrupted to instantaneously raise the pressure of the equipment, resulting in malfunction of the equipment.

On the other hand, the reducing gas 3 as described above is introduced into the melting furnace 40 through the DRI (2) or the mixture (2) of DRI and dust and the oxygen (1) through the triple tube burner (30). When DRI (2) or mixture (2) of DRI and dust and only oxygen (1) are introduced, DRI (2) is reoxidized by oxygen and the reduction rate is remarkably lowered. However, when they are introduced together with the reducing gas 3, the reduction ratio can be remarkably improved by preventing the reoxidation of the DRI 2, thereby remarkably reducing the reducing gas ratio.

At this time, the supply ratio of the reducing gas 3 and the oxygen 1 may be 7: 3 to 5: 5. When the supply ratio of the reducing gas and oxygen satisfies the above-described numerical value range, the flame length of the dust burner can be maintained as long and constant as possible, and the temperature of the dust burner can be maintained at 1000 ° C or higher. It is preferable that the amount of oxygen supplied to the dust burner does not exceed the supply amount of the reducing gas because DRI having a high metallization rate is likely to be reoxidized by oxygen when the oxygen supply ratio is increased.

In the present invention, it is preferable that the supply unit has a triple-pipe structure, and more specifically, it may be a triple-tube burner having nozzles.

Generally, the FINEX process is a process of producing molten iron by injecting briquetted reduced iron, which is manufactured in a fluidized-bed furnace, into a molten furnace together with molded coal. As described above, the reduced iron and the shaped coal produced in the flow furnace generate dust by thermal, mechanical and / or chemical differentiation during the reduction and melting reaction, and these dusts are contained in the molten gas and discharged therefrom. It is re-injected with oxygen to maintain an adequate level of reducing gas operation. More specifically, the dust scattered in the melting furnace is collected in the cyclone, then re-injected into the furnace through the dust burner, and the recirculated dust is burnt using oxygen to keep the dome temperature in the furnace constant at about 1000 ° C , The dust volatiles rising from the melting furnace bed were switched.

The above-mentioned dust burner has a double tube structure, and the unburned melted fine powder and oxygen are supplied. However, if the nozzle is clogged by the powdered dust or the like and the oxygen blowing becomes impossible, it becomes difficult to control the dome temperature during the operation. As a result, it is possible to prevent the reduction of the reducing gas, the HCI reduction rate, There have been problems in that the reduction gas ratio is increased and the core is unstable due to various problems.

Therefore, the inventors of the present invention have prevented the difficulty in controlling the dome temperature during operation by using the triple-tube burner having the nozzle as the supply portion. More specifically, oxygen (1) is injected through the nozzle; DRI (2) or a mixture of DRI and dust (2); And at least one reducing gas (3) selected from the group consisting of FOG and FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas, The DRI 2 can be directly charged to the upper end of the melting furnace 40 and the DRI 2 can be supplied without any separate briquetting process and / It can be used in the manufacture of charcoal.

3 shows an exemplary structure of a triple pipe burner according to the present invention. 3 (a) and 3 (b), the burner has a triple-pipe structure. In the present invention, depending on working conditions, .

First, in the case of the type of FIG. 3 (a), the reaction temperature can be improved because of excellent radiation heat transfer in the furnace. On the other hand, since the type is an oxidizing atmosphere having a large amount of oxygen, when DRI and / or dust reduced at high temperature are fed by the gas after the reaction and coexist, the equilibrium constant ) Is reduced and there is a possibility that DRI and / or dust are re-oxidized.

Next, in the case of the type of FIG. 3 (b), although the radiation heat transfer in the furnace is slower than that of the type shown in FIG. 3 (a), the amount of the reification reductant (O ₂ , H ₂ O and CO ₂ ) And retention time is short, rapid reoxidation can be initiated by Nucleation & Growth. Also, if a thick and dense oxide layer is formed thereafter, solid-state diffusion becomes a rate-limiting step of reoxidation and the rate of re-oxidation of DRI and / or dust can be significantly reduced since the overall re-oxidation rate is rapidly reduced.

Therefore, it is preferable to selectively apply the triple-tube burner of the 3 (a) type or the 3 (b) type in accordance with the operating condition and the operating condition.

Next, a method of manufacturing a molten iron according to the present invention will be briefly described.

The present invention relates to a method for producing a molten iron, comprising the steps of: direct reduction iron (DRI) having a metallization ratio of 80% or more; At least one reducing gas selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas; And introducing oxygen into the melting furnace.

At this time, as described above, the DRI having the metallization ratio of 80% or more directly uses the product manufactured by using the by-product of iron and iron without a separate pretreatment process. In particular, the DRI is not particularly limited as long as it has a size similar to that of the dust, and may be selected through a grid below the hollow, for example, having a particle diameter of 100 mu m or less.

Further, the DRI may further include dust having a particle diameter of 100 mu m or less through a grid disposed under the hot cyclone after being separated from the gas generated in the melting furnace through a hot cyclone, and the content ratio thereof is 10: To 5: 5. The details of this are as described above.

Meanwhile, in the process of separating the reducing gas and the dust from the gas generated in the melting furnace in the present invention, the operating temperature of the hot cyclone is preferably 700 ° C or more, and the efficiency of the hot cyclone is preferably 80% or more. The separated reducing gas flows out to the upper part of the hot cyclone and is supplied to the melting furnace through the triple tube burner. The dust is selected through the grid disposed at the lower part of the hot cyclone to have a particle diameter of 100 탆 or less . Also, a grid is disposed under the bins to perform a secondary sorting process on dust and dust having a particle diameter of 100 mu m or less and a DRI mixture. The separation and sorting as described above are preferably performed using a vibrator, though not limited thereto. This is because dust particles and DRI particles can be prevented from blocking the mesh of the screen when the vibrator is used and the time for selecting uniform particles can be shortened.

In addition, the detailed description of each configuration included in the manufacturing method of the present invention is as described above.

Generally, when the reduction ratio of the fluidized-bed reactor is increased by about 1%, there is an effect of reducing the reduction ratio of about 35 kg / tp. Therefore, according to the present invention, when the DRI produced by using the by-product of iron and iron is charged directly into the melting furnace without being subjected to a separate briquetting process and the like, Can be further improved, and the effect of reducing the reduction ratio can be ensured through this, which is very advantageous.

Hereinafter, the present invention will be described more specifically by way of specific examples.

Example  One

In order to investigate the melting phenomenon in FINEX process, DRI and CO gas with 90% metallization rate were blown into a self-made heating furnace simulator and the heating pattern and temperature range The gas composition was simulated as shown in Table 1 below.

Comparative Example  One

The same process as in Example 1 was carried out, except that DRI having a metallization ratio of 60% was blown into the heating furnace.

Comparative Example  2

The same process as in Example 1 was carried out except that DRI with a metallization ratio of 70% was blown into the heating furnace.

division Temperature Heating pattern Room temperature to 300 ° C, 20 ° C / min 300 ° C to 900 ° C, 15 ° C / min 900 ° C to 1350 ° C, 10 ° C / min 1350 ° C to 160 ° C, 5 ° C / min Gas composition Room temperature to 1100 ° C, 100% N ₂ 1100 ° C to 1350 ° C, 70% N ₂ + 30% CO 1350 ° C to 1600 ° C, 65% N ₂ + 35% CO

Experimental Example  - Melting  Temperature measurement

The melting temperature according to the change of the metallization ratio of DRI was measured in the process according to Example 1 and Comparative Examples 1 and 2, and is shown in Table 2 below. 4 (a) to 4 (c) show the results of photographing using a high-temperature photographic camera (TRV 70) to observe the degree of melting of the DRI.

division Melting temperature (캜) Example 1 1403 Comparative Example 1 1550 Comparative Example 2 1521

Referring to Table 2, it can be seen that as the metallization ratio of DRI increases, the melting temperature becomes lower. It is considered that the increase of softening temperature and the acceleration of carburizing reaction in the lower part of the melting bed are considered to be due to the increase of the content of M-Fe as the metallization rate included in the DRI increases. Therefore, the use of such a material can improve the air permeability in the melt bed.

That is, in the case of Example 1 which satisfied the range of the present invention, the melting temperature was lowered by 10.5% as compared with Comparative Example 1. That is, the melting temperature can be decreased as the metallization ratio is increased, and the reduction effect of the reduction ratio is more excellent as the melting temperature is lowered. Therefore, the results of the above Table 2 can remarkably reduce the reducing gas even when DRI having a metallization rate of 80% or more among the by-products of iron and iron is used for the production of molten iron without a separate briquetting process, And stable operation is possible.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments, but various modifications and changes may be made without departing from the scope of the invention. To those of ordinary skill in the art.

1: Oxygen
2: A mixture of DRI or DRI and dust
3: reducing gas
4: Gas generated from the melting furnace
5: Dust
10: Hot cyclone
20: bin
Burner with 30: 3 pipe nozzle
40: melting furnace
50: Horizontal tube
100: sticky molten Fe and FeO
200: agglomeration and carbon burning

Claims (15)

A direct reduction iron (DRI) having a metallization rate of 80% or more, a supply part for introducing a reducing gas and oxygen into the melting furnace; And
And a horizontal pipe to which methane is supplied for blowing the directly reduced iron or a mixture of the directly reduced iron and the dust into the melting furnace,
Wherein the reducing gas is at least one selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG), and melting furnace exhaust gas.
The method according to claim 1,
Wherein the direct reduced iron is selected through a grid at the bottom of the hollow and has a particle diameter of 100 mu m or less.
The method according to claim 1,
Wherein the direct reduced iron further comprises a dust separated from a gas generated in the melting furnace through a hot cyclone and then selected through a grid disposed under the hot cyclone to have a particle size of 100 mu m or less.
The method of claim 3,
Wherein the content ratio of the directly reduced iron and the dust is 7: 3 to 5: 5.
The method of claim 3,
Wherein the dust comprises carbon.
The method according to claim 1,
Wherein the supply ratio of the reducing gas and the oxygen is 7: 3 to 5: 5.
The method according to claim 1,
Wherein the reducing gas has a dust removed by 80% or more through a hot cyclone.
The method according to claim 1,
Wherein the supply unit has a triple pipe structure.
Introducing a direct reduction iron (DRI) having a metallization ratio of 80% or more, a reducing gas and oxygen into a melting furnace; And
Introducing a directly reduced iron through the methane load or a mixture of the directly reduced iron and the dust into the melting furnace,
Wherein the reducing gas is at least one selected from the group consisting of FOG, FINEX OFF gas, blast furnace gas (BFG), coke oven gas (COG) and melting furnace exhaust gas.
10. The method of claim 9,
Wherein the direct reduced iron is selected through a grid at the bottom of the hollow and has a particle diameter of 100 mu m or less.
10. The method of claim 9,
Wherein the direct reduced iron further comprises a dust separated from the gas generated in the melting furnace through a hot cyclone and then selected through a grid disposed under the hot cyclone to have a particle size of 100 mu m or less.
12. The method of claim 11,
Wherein the hot cyclone separation efficiency is 80% or more.
11. The method of claim 10,
Wherein the grid includes a vibrating device.
12. The method of claim 11,
Wherein the content of the directly reduced iron and dust is 7: 3 to 5: 5.
10. The method of claim 9,
Wherein the supply ratio of the reducing gas and the oxygen is 7: 3 to 5: 5.

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