Apparatus for manufacturing molten iron

Abstract

The present invention relates to a molten iron manufacturing apparatus and is characterized by comprising a converter section made of refractory material, an electrode section installed in the inner central part of the converter section, a raw material section formed in the inner outer part of the converter section by introducing raw materials around the outer perimeter of the electrode section, and an auxiliary raw material section formed in the inner inner part of the converter section by introducing auxiliary raw materials around the inner perimeter of the electrode section. Accordingly, the present invention provides the effect of enabling the introduction of a large amount of material relative to the same internal volume by introducing auxiliary raw materials with low electrical conductivity around the electrode rod, reducing heat loss compared to conventional methods, and increasing the carburization efficiency in molten iron through the formation of Fe3C, a carbonaceous compound, via chemical bonding within the furnace of the hydrogen reduction DRI.

Description

Technology Field

[0001] The present invention relates to a molten iron manufacturing apparatus, and more specifically, to a molten iron manufacturing apparatus for producing molten iron containing carbon when melting carbon-free DRI. Background Technology

[0002] Recently, in order to achieve carbon neutrality in the steel industry, there has been a transition from the conventional method of producing molten iron by reducing iron ore with carbon in blast furnaces to a process of producing molten steel in converters. Currently, technology is being developed for a process that produces direct reduction iron (DRI) by reducing iron ore with hydrogen, manufactures molten iron using an Electric Smelting Furnace (ESF) facility, and links it to a converter.

[0003] Since the DRI added to the ESF does not contain carbon, there is a need to develop a technology to carburize more than 3 wt% of carbon in the molten metal, but since this has not yet been established, various studies are being conducted.

[0004] To date, specialized equipment suppliers such as Hatch, SMS, and Tenova have proposed open arc or immersed arc operation methods for forming an arc on the slag surface, as controlling the electrode rod is difficult when DRI is injected around the electrode rod due to the high electrical conductivity of DRI. However, there have been problems with high heat loss from the flue gas and reduced carburization efficiency in the molten iron when coke, a reducing agent, is physically mixed and injected.

[0005] Therefore, there is no technology to produce molten iron by introducing carbon-free, highly conductive DRI into the ESF, and steel mills and specialized engineering firms have had a problem in that it is difficult to control the electrode rods because when a highly conductive material comes into contact with the electrode rods, a short circuit occurs, causing the current to be conducted directly to the raw material instead of flowing to the molten iron.

[0006] That is, as shown in FIGS. 4 and 5, an open arc method or an immersed arc method is used in which a raw material (1) mixed with DRI, coke, and auxiliary raw materials is formed around the electrode rod (1) without contacting the electrode rod (2), and the electrode rod (2) is immersed on the upper surface of the slag or at a certain depth.

[0007] However, this conventional method had the problem that the arc generated from the electrode rod was exposed, resulting in low thermal efficiency in transferring heat to the raw material and consequently raising the temperature of the exhaust gas. This caused the roof or parts of the constructed refractory material exposed to the exhaust gas to deteriorate, making it difficult to apply the refractory materials used in existing ESFs. Furthermore, when installing alternative cooling systems using air or water as a refrigerant, heat loss increased, leading to a problem where the amount of electricity required for the ESF increased.

[0008] In addition, when the DRI does not contain carbon, it is necessary to mix and add carbon-based reducing agents such as coal and coke to produce carbon-containing molten iron and further reduce unreduced FeO within the DRI; however, there was also a problem in that physically adding the reducing agent reduced the efficiency of FeO reduction in the DRI and the carburization of the molten iron. Prior art literature

[0009] Republic of Korea Registered Patent No. 10-0426852 (April 13, 2004) Republic of Korea Registered Patent No. 10-0370920 (February 5, 2003) Republic of Korea Registered Patent No. 10-0543186 (January 20, 2006) The problem to be solved

[0010] The present invention has been devised to resolve the aforementioned conventional problems and aims to provide a molten iron manufacturing apparatus capable of introducing a large amount of material relative to the same volume by introducing auxiliary materials with low electrical conductivity around the electrode rod, having less heat loss compared to existing methods, and increasing the carburization efficiency within the molten iron through the formation of Fe3C, a carbonaceous compound, via chemical bonding inside the furnace of the hydrogen reduction DRI.

[0011] In addition, another objective of the present invention is to provide a molten iron manufacturing apparatus that reduces the input amount of carbon-based reducing agent by improving carburization efficiency relative to the physical input amount of coke through Fe3C chemical bonding, and reduces the power input amount by partially transferring the heat energy of the flue gas flow directly to the main body cooling facility to DRI and auxiliary raw materials.

[0012] In addition, another objective of the present invention is to provide a molten iron manufacturing apparatus that can be applied to the field of operation technology of an electric melting reduction furnace (ESF) and to various technical fields related to the melting, reduction, and carburization of raw materials containing conductive materials, by efficiently carburizing to produce molten iron containing at least 3% carbon when melting carbon-free DRI.

[0013] In addition, another objective of the present invention is to provide a molten iron manufacturing apparatus capable of minimizing heat loss by changing the charging profile of raw materials input into the furnace and reducing the amount of reducing agent input by improving the reaction efficiency of a carbon-based reducing agent injected alone.

[0014] In addition, another objective is to provide a molten iron manufacturing device capable of preventing breakage by allowing current to pass through the molten iron and transferring the generated heat to the input raw materials, by introducing low-electrical conductivity auxiliary raw materials such as dolomite, limestone, and quicklime individually around the electrode rod without mixing them with DRI and Coke. means of solving the problem

[0015] The present invention for achieving the above-mentioned purpose comprises: a converter section (10) made of refractory material; an electrode section (20) installed in the inner central portion of the converter section (10); a raw material section (30) formed in the inner outer portion of the converter section (10) by introducing raw material into the outer circumference of the electrode section (20); and a secondary raw material section (40) formed in the inner inner portion of the converter section (10) by introducing secondary raw material into the inner circumference of the electrode section (20).

[0016] The present invention is further characterized by including a coke bed portion (70) formed at the lower part of the electrode portion (20).

[0017] The converter section (10) of the present invention is characterized by comprising: a first input means installed to input raw materials around the outer circumference of the upper cover of the converter; and a second input means installed to input auxiliary raw materials around the inner circumference of the upper cover of the converter.

[0018] The above raw material of the present invention is characterized by comprising DRI (direct reduction iron) and coke. The above auxiliary raw material of the present invention is characterized by comprising at least one of dolomite, limestone, and quicklime. Effects of the invention

[0019] As described above, the present invention enables the introduction of a large amount of material relative to the same volume by introducing auxiliary materials with low electrical conductivity around the electrode rod, reduces heat loss compared to conventional methods, and provides the effect of increasing the carburization efficiency in molten iron through the formation of Fe3C, a carbonaceous compound, via chemical bonding within the furnace of the hydrogen reduction DRI.

[0020] In addition, the amount of carbon-based reducing agent input is reduced by improving carburization efficiency relative to the physical input amount of coke through Fe3C chemical bonding, and the heat energy from flue gas flow, which is directly transferred to the main body cooling facility, is partially transferred to DRI and auxiliary materials, thereby providing the effect of reducing power input.

[0021] In addition, by efficiently carburizing to produce molten iron containing at least 3% carbon when melting carbon-free DRI, it is applicable to the field of operation technology for electric melting reduction furnaces (ESF) and also provides the effect of being applicable to various technology fields related to the melting, reduction, and carburization of raw materials containing conductive materials.

[0022] In addition, it provides the effect of minimizing heat loss by changing the charging profile of raw materials in the furnace and improving the reaction efficiency of the carbon-based reducing agent injected alone, thereby reducing the amount of reducing agent input.

[0023] In addition, instead of mixing and adding auxiliary materials with low electrical conductivity such as dolomite, limestone, and quicklime with DRI and Coke, adding them alone around the electrode rod allows current to pass through the molten iron, preventing breakage and providing the effect of transferring the generated heat to the added materials. Brief explanation of the drawing

[0024] FIG. 1 is a schematic diagram showing a molten iron manufacturing apparatus according to one embodiment of the present invention. FIG. 2 is a configuration diagram showing another example of a molten iron manufacturing apparatus according to one embodiment of the present invention. FIG. 3 is a plan view showing another example of a molten iron manufacturing apparatus according to one embodiment of the present invention. FIG. 4 is a schematic diagram showing a conventional molten iron manufacturing apparatus. FIG. 5 is a plan view showing a conventional molten iron manufacturing apparatus. FIG. 6 is a schematic diagram showing a typical molten iron manufacturing apparatus. Figure 7 is a graph showing the performance of a typical molten iron manufacturing device. Specific details for implementing the invention

[0025] Hereinafter, a preferred embodiment of the present invention will be described in more detail with reference to the attached drawings.

[0026] FIG. 1 is a configuration diagram showing a molten iron manufacturing apparatus according to one embodiment of the present invention, FIG. 2 is a configuration diagram showing another example of a molten iron manufacturing apparatus according to one embodiment of the present invention, and FIG. 3 is a plan view showing another example of a molten iron manufacturing apparatus according to one embodiment of the present invention.

[0027] As shown in FIGS. 1 to 3, the molten iron manufacturing apparatus according to the present embodiment comprises a converter section (10), an electrode section (20), a raw material section (30), and an auxiliary raw material section (40), and is a molten iron manufacturing apparatus that adopts a submerged arc method for manufacturing molten iron.

[0028] The converter section (10) is a converter member made of refractory material, having a slag section (50) and a molten iron section (60) formed at the bottom, and comprises a first input means (13) installed to input raw materials around the outer circumference of the upper cover (11) of the converter (12), and a second input means (14) installed to input auxiliary raw materials around the inner circumference of the upper cover (11) of the converter (12).

[0029] The first input means (13) is an input member installed to input raw materials on the outer perimeter of the upper cover (11) of the converter (12), and is composed of a plurality of input holes spaced apart at equal intervals along the outer perimeter to input raw materials mixed with DRI (direct reduction iron) and coke into the inner outer perimeter of the converter (12).

[0030] The second input means (14) is an input member installed to input auxiliary materials into the inner circumference of the upper cover (11) of the converter (12), and is composed of a plurality of input holes spaced apart at equal intervals along the inner circumference to allow auxiliary materials with low electrical conductivity, such as dolomite, limestone, and quicklime, to be loaded into the inner circumference of the converter (12).

[0031] The electrode section (20) is an electrode member installed in the central part of the internal section (10), and is composed of an electrode rod that receives power from an external power facility and generates an arc inside the section (10) to form molten iron.

[0032] The raw material section (30) is formed in the inner outer portion of the converter section (10) and is a raw material member formed by introducing raw material into the outer circumference of the electrode section (20). It is preferable that the raw material consists of a mixture of DRI (direct reduction iron) and coke.

[0033] The auxiliary material part (40) is formed in the inner part of the converter part (10) and is an auxiliary material member formed by introducing an auxiliary material around the inner circumference of the electrode part (20). It is preferable that such auxiliary material includes at least one of dolomite, limestone, and quicklime, which have low electrical conductivity, or is composed of an auxiliary material with low electrical conductivity such as dolomite, limestone, and quicklime.

[0034] Of course, the molten iron manufacturing apparatus of the present invention may further include a coke bed portion (70) formed at the lower part of the electrode portion (20).

[0035] The coke bed section (70) is coke formed at the bottom of the electrode section (20), and is formed between the electrode section (20) and the slag section (50), adopting a submerged arc method in which the electrode rod of the electrode section (20) is embedded in the coke bed section (70).

[0036] As shown in FIG. 3, which is a top view of the raw material charging profile, the molten iron manufacturing apparatus of the present invention is of the rectangular type, with a total of 6 electrode rods of the electrode part (20) used.

[0037] Therefore, the current flow transmitted through the electrode rods is such that the 1st and 2nd electrode rods, the 3rd and 4th electrode rods, and the 5th and 6th electrode rods are coupled, allowing current to flow.

[0038] In addition, the raw material section (30) is marked with an area for loading DRI and Coke, and the auxiliary raw material section (40) is arranged so that an auxiliary raw material, which is a non-conductive material, can be inserted into the section through which current flows to cover the electrode rod.

[0039] In addition, the coke bed section (70) is a section for introducing auxiliary raw materials and coke, and it is preferable to arrange it so that only auxiliary raw materials are loaded and the electrode rod is covered when the amount of coke introduced in the area of ​​the raw material section (30) is sufficient.

[0040] As shown in Figure 6, the operation method of the Electric Smelting Furnace (ESF) for manufacturing ferroalloys is broadly classified into four types. Generally, the Open Arc method is adopted when melting high-conductivity raw materials. However, since most raw materials for manufacturing ferroalloys do not have high electrical conductivity, the Immersed Arc, Shielded Arc, and Submerged Arc methods are adopted depending on the operating conditions.

[0041] The immersed arc method is a method in which raw materials surround the electrode rod and the tip of the electrode rod is immersed in molten slag. It is advantageous for slag with high electrical resistance due to heat generation caused by the resistance heat of the slag, and heat convection occurs from the superheated slag near the tip of the electrode rod outward.

[0042] The shielded arc method involves raw materials surrounding an electrode rod and generating a short arc on top of the slag; this method has the advantage of high thermal efficiency because the surrounding raw materials absorb the arc's energy.

[0043] The submerged arc has the advantage of forming a coke bed layer on top of the slag, similar to a blast furnace, and utilizing resistance heat through immersion inside the coke bed to form a heat source, allowing for heat transfer and additional reduction as the CO gas generated inside passes through the charge.

[0044] The molten iron manufacturing apparatus of the present invention uses a method of introducing auxiliary materials around the electrode rod as a means to minimize heat loss within the Electric Smelting Furnace (ESF).

[0045] Accordingly, the molten iron manufacturing apparatus of the present invention relates to a method of operating DRI, a highly conductive iron raw material, using a shielded arc or submerged arc method rather than an open arc method.

[0046] In other words, the present invention allows dolomite, limestone, quicklime, etc., as auxiliary raw materials with low electrical conductivity to be introduced alone around the electrode rod without being mixed with DRI and Coke, thereby preventing breakage of the current through the molten iron and enabling the heat generated thereby to be transferred to the introduced raw materials.

[0047] In particular, the shielded arc method has the advantage of increasing power usage efficiency by allowing an additional arc to be formed in the air layer between the electrode tip and the slag, thereby enabling a high power factor (ratio of apparent power to active power).

[0048] In the case of the submerged arc method, only the resistance heat of the coke bed can be utilized, so the power factor is relatively lower compared to the shielded arc method. However, through the CO gas generated through the coke bed, stable carbon-based compounds such as Fe3C are formed in the metal Fe and oxide FeO contained in the DRI in the 800~1000℃ range, and the CO2 gas generated after the reaction reacts with carbon again in the range of 1000℃ or higher to become CO gas, which further contributes to the formation of the Fe3C compound as shown in Chemical Formula 1 below.

[0049] [Chemical Formula 1]

[0050] 3Fe + 2CO = Fe3C + 4CO2

[0051] 3FeO + 5CO = Fe3C + 4CO2

[0052] CO2 + C = 2CO

[0053] In particular, the formation of the carbonaceous compound Fe3C increases the carburization efficiency compared to when a carbonaceous reducing agent is added alone during molten iron production. This is because, in the case of an EAF (Electric arc furnace) that produces molten steel by melting scrap and high-grade DRI containing carbon, the yield is about 60% when carbonaceous material is injected alone, but it is known that the yield is higher than 95% when a compound such as Fe3C is injected. Therefore, when producing actual carbon-containing DRI, the carbon content is important, but the content of compounds existing in the form of Fe3C is also evaluated.

[0054] There are two main types of DRI manufacturing methods. As can be seen from the graph in Figure 7, when 3% carbon is present in the DRI, the proportion of the Fe3C form in the DRI is evaluated to be 80% in the case of the Midrex process and 95% in the case of the Energiron process.

[0055] As described above, according to the present invention, by introducing auxiliary materials with low electrical conductivity around the electrode rod, it is possible to introduce a large amount of material relative to the same volume, and compared to conventional methods, heat loss is reduced. Furthermore, the invention provides the effect of increasing the carburization efficiency in molten iron through the formation of Fe3C, a carbonaceous compound, via chemical bonding within the furnace of the hydrogen reduction DRI.

[0056] In addition, the amount of carbon-based reducing agent input is reduced by improving carburization efficiency relative to the physical input amount of coke through Fe3C chemical bonding, and the heat energy from flue gas flow, which is directly transferred to the main body cooling facility, is partially transferred to DRI and auxiliary materials, thereby providing the effect of reducing power input.

[0057] In addition, by efficiently carburizing to produce molten iron containing at least 3% carbon when melting carbon-free DRI, it is applicable to the field of operation technology for electric melting reduction furnaces (ESF) and also provides the effect of being applicable to various technology fields related to the melting, reduction, and carburization of raw materials containing conductive materials.

[0058] In addition, it provides the effect of minimizing heat loss by changing the charging profile of raw materials in the furnace and improving the reaction efficiency of the carbon-based reducing agent injected alone, thereby reducing the amount of reducing agent input.

[0059] In addition, instead of mixing and adding auxiliary materials with low electrical conductivity such as dolomite, limestone, and quicklime with DRI and Coke, adding them alone around the electrode rod allows current to pass through the molten iron, preventing breakage and providing the effect of transferring the generated heat to the added materials.

[0060] The invention described above may be implemented in various other forms without departing from its technical concept or main features. Accordingly, the above embodiments are merely examples in all respects and should not be interpreted restrictively. Explanation of the symbols

[0061] 10: Electric Railway 20: Electrode part 30: Raw Materials Department 40: Auxiliary Raw Materials Department 50: Slag section 60: Chartered boat division 70: Coke bed

Claims

Claim 1 A converter section (10) made of refractory material; an electrode section (20) installed in the inner central portion of the converter section (10); a raw material section (30) formed in the inner outer portion of the converter section (10) by introducing raw material around the outer circumference of the electrode section (20); a secondary raw material section (40) formed in the inner inner portion of the converter section (10) by introducing secondary raw material around the inner circumference of the electrode section (20); and a coke bed section (70) formed at the bottom of the electrode section (20); wherein the converter section (10) comprises a first input means installed to introduce raw material around the outer circumference of the upper cover of the converter; and a second input means installed to input auxiliary materials into the inner circumference of the upper cover of the converter; wherein the first input means is composed of a plurality of input holes spaced apart at equal intervals along the outer circumference to charge a raw material mixed with DRI (direct reduction iron) and coke into the inner outer circumference of the converter, and the second input means is composed of a plurality of input holes spaced apart at equal intervals along the inner circumference to charge auxiliary materials with low electrical conductivity, such as dolomite, limestone, and quicklime, into the inner inner circumference of the converter, and the coke bed section (70) is formed between the electrode section (20) and the slag section (50) and the electrode rod of the electrode section (20) is embedded therein, and the coke bed section (70) is a section for inputting auxiliary materials and coke, and when the amount of coke input is sufficient in the area of ​​the raw material section (30), only the auxiliary materials A molten iron manufacturing apparatus characterized by being arranged to cover an electrode rod by loading. Claim 2 delete Claim 3 delete Claim 4 A molten iron manufacturing apparatus according to claim 1, characterized in that the raw materials include DRI (direct reduction iron) and coke. Claim 5 A molten iron manufacturing apparatus according to claim 1, characterized in that the auxiliary raw material comprises at least one of dolomite, limestone, and quicklime.

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