Electric furnace operation method

Abstract

Provided is an electric furnace operation method. This electric furnace operation method comprises: a step for melting a first iron source in a first furnace in which a first electrode part is disposed; a step for preheating a second iron source in a second furnace in which a second electrode section is disposed; and a step of melting the second iron source in the second melting furnace, the first melting furnace and the second melting furnace sharing an internal space, in the step of preheating the second iron source, the second electrode part releases a first gas, in the step of melting the second iron source, the second electrode part releases a second gas, and in the step of melting the second iron source, the second electrode part releases a second gas. The second electrode portion releases a second gas different from the first gas.

Description

Technical Field

[0001] The invention relates to an electric furnace operating method. Background Art

[0002] Generally speaking, the steel production process in the iron and steel industry can be roughly divided into the blast furnace-converter production system (converter process), which uses ore as the main raw material, and the electric furnace production system (electric furnace process), which uses scrap (scrap) recovered / reused after the produced steel is commercialized as a main raw material.

[0003] The BOF process, based on ore, is widely used to produce high-quality products, primarily plate products that are sensitive to surface defects. The EAF process, however, can contain impurities (Cu, Sn, Cr, Mo, Ni, etc., collectively referred to as tramp elements) and is therefore generally suitable for the production of bars and sections requiring high strength.

[0004] Moreover, as carbon neutrality has recently become a global focus, the electric furnace process, which produces ≤20% CO2 compared to the converter process, is becoming an alternative for future steel production.

[0005] In the case of an electric furnace process, surface defects generated during a continuous casting process tend to be aggravated during a rolling process due to residual (tramp) elements flowing from scrap, and may have a characteristic of poor workability.

[0006] In order to overcome this limitation, the active use of ore-based iron sources (OBM's: Ore Based Materials) based on iron ore (ex. DRI, HBI, PI, GPI, etc.) is becoming an alternative.

[0007] Representative examples include direct reduced iron (DRI / HBI), which produces iron as a source of iron by processing iron ore into pellets and reacting them with reducing gas, unlike in blast furnaces. Currently, an increasing number of electric furnace steel companies are using commercial equipment to produce plate products.

[0008] When ore-based iron sources are fed into an electric furnace, the reducing gas permeates the solid raw material and reacts with the reducing structure, which may result in a large amount of unreduced iron oxide (FeO). This may increase slag production and reduce molten steel recovery.

[0009] Furthermore, due to the nature of the process of using an arc (electric energy) to dissolve scrap, nitrogen (N2) gas in the air around the electrode can be ionized (plasma), thereby causing the arc flow to be injected into the molten steel. Therefore, it may be difficult to control the nitrogen (N2) content. Summary of the Invention

[0010] Technical issues

[0011] The problem to be solved by the present invention is to provide an electric furnace operation method that can effectively reduce iron oxide (FeO) contained in slag and improve the recovery rate of molten steel even when direct reduced iron is used in the electric furnace.

[0012] Another problem to be solved by the present invention is to provide an electric furnace operation method that can more smoothly adjust the nitrogen (N2) content in the molten steel in the electric furnace.

[0013] Problems of the present invention are not limited to the problems mentioned above, and those skilled in the art can clearly understand other problems not mentioned through the following description.

[0014] Solutions to the Problem

[0015] An electric furnace operation method according to one embodiment for solving the above-mentioned problem includes: a step of melting a first iron source in a first melting furnace equipped with a first electrode portion; a step of preheating a second iron source in a second melting furnace equipped with a second electrode portion; and a step of melting the second iron source in the second melting furnace, wherein the first melting furnace and the second melting furnace share an internal space, and in the step of preheating the second iron source, the second electrode portion releases a first gas, and in the step of melting the second iron source, the second electrode portion releases a second gas different from the first gas.

[0016] The first gas may include a reducing gas, and the second gas may include an inert gas.

[0017] The reducing gas may include at least one selected from carbon dioxide (CO 2 ) gas, methane (CH 4 ) gas, and hydrogen (H 2 ) gas, and the inert gas may include argon (Ar) gas.

[0018] The first gas may further include an inert gas.

[0019] The step of melting the second iron source may include an initial melting step and a later melting step, in which the second electrode portion releases the second gas in the initial melting step and the second electrode portion releases a third gas different from the second gas in the later melting step.

[0020] The second gas may include an inert gas, and the third gas may include a reducing gas.

[0021] In the initial melting step, the second electrode portion may be exposed to the outside, and in the later melting step, at least a portion of the second electrode portion may be immersed in the slag.

[0022] The step of melting the first iron source may be performed simultaneously with the steps of preheating the second iron source and melting the second iron source.

[0023] In the step of melting the first iron source, the first electrode portion may release a third gas.

[0024] The third gas may include a reducing gas.

[0025] The present invention may also include a step of mixing the first slag inside the first furnace and the second slag inside the second furnace, and refining the molten metal. In the step of refining the molten metal, the first electrode part may release a third gas, the second electrode part may release a fourth gas, and the third gas and the fourth gas may contain a reducing gas.

[0026] The first electrode portion may include a first AC electrode rod, a second AC electrode rod, and a third AC electrode rod, and the second electrode portion may include an upper DC electrode and a lower DC electrode.

[0027] The upper DC electrode may include: an internal tube, which is arranged to penetrate the upper DC electrode in the length direction and can allow at least one of the first gas and the second gas to flow; a gas supply part, which is located on one side of the internal tube to supply at least one of the first gas and the second gas; and a gas release part, which is located on the other side of the internal tube to release at least one of the first gas and the second gas.

[0028] The first iron source may comprise an ore-based iron source and the second iron source may comprise scrap.

[0029] An electric furnace operation method according to one embodiment for solving the above-mentioned problem includes: a step of introducing an iron source into an electric furnace including an electrode portion; a step of applying power to the electrode portion to melt the iron source; and a step of blowing oxygen into the electric furnace and performing refining, wherein during the step of melting the iron source, the electrode portion releases a first gas, and during the step of performing refining, the electrode portion releases a second gas different from the first gas.

[0030] The first gas may include an inert gas, and the second gas may include a reducing gas.

[0031] The electrode part may include a first AC electrode rod, a second AC electrode rod, and a third AC electrode rod.

[0032] The first AC electrode rod, the second AC electrode rod, and the third AC electrode rod can respectively release at least one of the first gas and the second gas from the inside.

[0033] An electric furnace operation method of one embodiment for solving the above-mentioned problem includes an electrode rod and has a space inside for accommodating at least one of an iron source, a fusible wire and a slag, including: a step in which the electrode rod releases a first gas containing an inert gas; and a step in which the electrode rod releases a second gas containing a reducing gas, wherein in the step in which the first gas is released, one end of the electrode rod is exposed, and in the step in which the second gas is released, the one end of the electrode rod is located inside the slag.

[0034] The electrode rod may include: an inner tube in which the first gas and the second gas flow; and a gas release portion located on one side of the inner tube and releasing the first gas and the second gas, wherein the gas release portion is configured at the end of one side of the electrode rod.

[0035] Details of other embodiments are included in the detailed description and drawings.

[0036] Effects of the Invention

[0037] According to an electric furnace operation method of one embodiment, even when direct reduced iron is used in an electric furnace, iron oxide (FeO) contained in slag can be effectively reduced and the recovery rate of molten steel can be improved.

[0038] According to an electric furnace operation method of one embodiment, the nitrogen (N2) content in molten steel in the electric furnace can be adjusted more smoothly.

[0039] The effects of the embodiment are not limited to the above-described examples, and more effects are included in this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure is a cross-sectional view schematically showing an electric furnace according to an embodiment.

[0041] Figure 2 FIG. 4 is a cross-sectional view of an upper DC electrode according to an embodiment.

[0042] Figure 3 This is a sequence diagram of an electric furnace operation method according to an embodiment.

[0043] Figures 4 to 9 sectional views of different process steps of an electric furnace operation method according to one embodiment.

[0044] Figure 10 This is a graph showing the behavior of nitrogen in the different steps of the electric furnace operation method.

[0045] Figure 11 This is a sequence diagram of an electric furnace operation method according to another embodiment.

[0046] Figure 12 and Figure 13 for Figure 11 Cross-sectional views of different process steps of the electric furnace operation method according to an embodiment. DETAILED DESCRIPTION

[0047] Below, refer to the attached Figure 1 The advantages, features, and methods of achieving these advantages and features of the present invention will be further clarified by the following detailed embodiments. However, the present invention is not limited to the following embodiments and can be implemented in various different ways. These embodiments are provided to complete the disclosure of the present invention and to enable those skilled in the art to fully understand the scope of the present invention. The present invention is defined solely by the claims.

[0048] In this specification, when a certain structural element (or region, layer, part, etc.) is mentioned as being "located", "connected", or "combined" with other structural elements, this means that it can be directly configured / connected / combined with other structural elements or a third structural element can be configured between them.

[0049] The same reference numerals refer to the same structural elements. In addition, in the drawings, the thickness, proportions, and sizes of the structural elements are exaggerated for the purpose of effectively explaining the technical content.

[0050] "And / or" includes all related structures that can define more than one structure.

[0051] Terms such as first and second can be used to describe a variety of structural elements, but the structural elements should not be limited by the terms. The terms are only used to distinguish one structural element from other structural elements. For example, without departing from the scope of protection of the present invention, the first structural element can be named as the second structural element, and similarly, the second structural element can be named as the first structural element. As long as there is no clear different meaning in the context, the expression in the singular includes the expression in the plural.

[0052] Furthermore, terms such as "lower," "lower side," "upper," and "upper side" are used to describe the relationship between the structures shown in the drawings. These terms are relative concepts and are described based on the directions shown in the drawings.

[0053] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) have the same meanings as those commonly understood by persons of ordinary skill in the art to which this invention pertains. Furthermore, commonly used terms that are equivalent to dictionary-defined terms should be interpreted as having meanings consistent with those in the relevant technical context and are explicitly defined herein unless they are interpreted as idealistic or formalistic.

[0054] It should be understood that terms such as "including" or "having" are intended to specify the features, numbers, steps, actions, structural elements, parts or their combinations recorded in the specification, rather than excluding the existence or additional possibility of one or more other features or numbers, steps, actions, structural elements, parts or their combinations in advance.

[0055] Figure 1 The figure is a cross-sectional view schematically showing an electric furnace according to an embodiment.

[0056] Reference Figure 1 The electric furnace 1000 of one embodiment may include a first upper unit 100 , a second upper unit 200 , a lower unit 300 , a partition unit 400 , an exhaust duct 500 , a gas low blowing device 600 , and a tilting device 700 .

[0057] The electric furnace 1000 may be a double-layer furnace structure constituting a main body sharing the lower unit 300. In the electric furnace 1000, the first upper unit 100 and the second upper unit 200 may share the lower unit 300 and be combined with the lower unit 300.

[0058] The electric furnace 1000 may further include a first melting furnace 10 and a second melting furnace 20 capable of melting different iron sources. The first upper unit 100 and the lower unit 300 may constitute the first melting furnace 10 and may define a first upper space A1-1 and a first lower space A1-2 of the first melting furnace 10. The second upper unit 200 and the lower unit 300 may constitute the second melting furnace 20 and may define a second upper space A2-1 and a second lower space A2-2 of the second melting furnace 20.

[0059] The electric furnace 1000 may include a double-layer furnace F in which at least a portion of the first and second furnaces 10 and 20 are structurally combined. The double-layer furnace F may have a structure in which the upper cells 100 and 200 of the first and second furnaces 10 and 20 are formed separately, and the lower cell 300 is formed as a single cell. The first and second furnaces 10 and 20 may be combined to share an internal space provided by the upper cells 100 and 200 and the lower cell 300.

[0060] The lower unit 300 may include an outlet 310 for discharging the molten metal 3 and / or slag 4a, 4b from the first melting furnace 10 and the second melting furnace 20. The outlet 310 may be disposed on the first melting furnace 10 side.

[0061] However, the position of the cavity outlet 310 is not limited to that shown in the figure, and the cavity outlet 310 may also be arranged on the side of the second melting furnace 20. Alternatively, the cavity outlet 310 may be arranged on the first melting furnace 10 and the second melting furnace 20 respectively.

[0062] The first melting furnace 10 may include a space therein for accommodating the first iron source 1, the first slag 4a, and the molten metal 3. The first iron source 1 may be loaded into the first melting furnace 10 and melted. The first iron source 1 may be continuously fed into the first melting furnace 10 via the iron source supply unit 120. The first melting furnace 10 may include a continuous melting mechanism that controls the energy input according to the rate at which the first iron source 1 is fed.

[0063] Without being limited thereto, the first iron source 1 may include ore-based materials (OBM's) (ferric oxide, DRI, HBI, PI, GPI, LRI, etc.), and may also include a portion of low-granularity waste (shredder, feed line, etc.).

[0064] The first melting furnace 10 may include a first slag door 11. The first slag 4a inside the first melting furnace 10 may be selectively discharged through the first slag door 11. Thus, the level of the first slag 4a inside the first melting furnace 10 may be controlled.

[0065] A plurality of first slag doors 11 may be provided around the first melting furnace 10 near the boundary between the first upper cell 100 and the lower cell 300. The first slag door 11 may include an upper door 11a that opens upward (on one side of the Z axis) and a lower door 11b that opens downward (on the other side of the Z axis). In other words, the first slag door 11 may be formed as a double-layered door.

[0066] However, the structure of the first slag door 11 is not limited to the above description. The first slag door 11 can be embodied as a single door to perform opening and closing actions.

[0067] The second melting furnace 20 may have a space therein that can accommodate the second iron source 2 , the second slag 4 b , and the molten metal 3 . The molten metal 3 may be accommodated via the first melting furnace 10 and the second melting furnace 20 .

[0068] A second iron source 2, different from the first iron source 1, can be charged into the second melting furnace 20 and melted. The preheating supply unit 220 preheats the second iron source 2 before it is placed in the second melting furnace 20. This improves the operating speed and efficiency of the second melting furnace 20.

[0069] Without being limited thereto, the second iron source 2 may include scrap and may also include a portion of a high-grained ore-based iron source.

[0070] The second melting furnace 20 may include a second slag door 21. The second slag 4b inside the second melting furnace 20 may be selectively discharged through the second slag door 21. Thus, the level of the second slag 4b inside the second melting furnace 20 may be controlled.

[0071] A plurality of second slag doors 21 may be provided along the periphery of the second melting furnace 20 near the boundary between the second upper cell 200 and the lower cell 300. The second slag door 21 may be opened during operation and then reclosed.

[0072] The first upper unit 100 may include a first electrode portion 110 and at least one iron source supplier 120 .

[0073] The first electrode portion 110 may be disposed in the first melting furnace 10. The first electrode portion 110 may penetrate the first upper unit 100 to be at least partially inserted into the first upper space A1-1 of the first melting furnace 10. The first electrode portion 110 may generate arc heat, which may melt the first iron source 1 loaded into the first melting furnace 10.

[0074] The first electrode unit 110 may include a first AC electrode rod 111, a second AC electrode rod 112, and a third AC electrode rod 113. Three-phase AC can be applied to the first electrode unit 110 via the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113. The first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113 may be connected to a power source (not shown) that can provide power.

[0075] The first electrode unit 110 may be connected to the gas supply pipe GP. Specifically, the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113 may be connected to the first gas supply pipe GP1, the second gas supply pipe GP2, and the third gas supply pipe GP3, respectively.

[0076] The first, second, and third AC electrode rods 111, 112, and 113 receive various gases from the gas storage tank GS through the first, second, and third gas supply pipes GP1, GP2, and GP3. The gas storage tank GS may include multiple sub-tanks for storing different types of gases.

[0077] The first, second, and third AC electrode rods 111, 112, and 113 can emit different gases according to the operation steps of the electric furnace 1000. This allows the operation steps of the electric furnace 1000 to be performed more smoothly. Detailed description of this will be given later.

[0078] The iron source supply units 120 can be arranged radially about the center of the first electrode unit 110. The iron source supply units 120 can supply the first iron source 1 into the first melting furnace 10. Multiple iron source supply units 120 can continuously supply the first iron source 1 to the three ignition points formed between the first, second, and third AC electrode rods 111, 112, and 113, thereby improving melting efficiency.

[0079] The second upper unit 200 may be disposed side by side with the first upper unit 100. The second upper unit 200 may include a second electrode unit 210 and a preheat supply unit 220.

[0080] The second electrode unit 210 may be disposed in the second melting furnace 20. The second electrode unit 210 may penetrate the first upper unit 100 to be at least partially inserted into the second upper space A2-1 of the second melting furnace 20. The second electrode unit 210 may generate arc heat, which may melt the second iron source 2 loaded into the second melting furnace 20.

[0081] The second electrode portion 210 may include an upper DC electrode 211 and a lower DC electrode 212. The upper DC electrode 211 and the lower DC electrode 212 may be disposed opposite to each other. The upper DC electrode 211 and the lower DC electrode 212 may be energized to generate an arc.

[0082] The lower DC electrode 212 may include a first lower electrode 212a and a second lower electrode 212b. The first lower electrode 212a may be disposed along the length of the upper DC electrode 211 and facing the upper DC electrode 211. The second lower electrode 212b may be disposed with respect to the upper DC electrode 211 and offset toward the preheat supply unit 220.

[0083] After the second iron source 2 is supplied to the second melting furnace 20, the second electrode unit 210 may cause current to flow between the upper DC electrode 211 and the second lower electrode 212b. After the second iron source 2 is melted, the second electrode unit 210 may cause current to flow between the upper DC electrode 211 and the first lower electrode 212a.

[0084] Depending on whether the second iron source 2 is melted, the upper DC electrode 211 can selectively energize different lower electrodes, thereby controlling the input flow of electrical energy and guiding an effective melting operation.

[0085] The upper DC electrode 211 may be connected to the fourth gas supply pipe GP4 of the gas supply pipe GP, respectively. The upper DC electrode 211 may receive a plurality of types of gases from the gas storage tank GS through the fourth gas supply pipe GP4.

[0086] The upper DC electrode 211 can eject different gases according to the operation steps of the electric furnace 1000. This allows the operation steps of the electric furnace 1000 to be carried out more smoothly. Detailed description of this will be given later.

[0087] The first AC electrode rod 111, the second AC electrode rod 112, the third AC electrode rod 113 and the upper DC electrode 211 may include a space inside thereof for gas to flow, thereby allowing gas to be ejected. Figure 2 .

[0088] Figure 2 FIG. 2 is a cross-sectional view of the upper DC electrode 211 according to an embodiment.

[0089] exist Figure 2 Although the description is given based on the upper DC electrode 211, the description of the upper DC electrode 211 is substantially applicable to the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113.

[0090] Reference Figure 2 The upper DC electrode 211 may be connected to the fourth gas supply pipe GP4 and receive gas from the fourth gas supply pipe GP4. The upper DC electrode 211 may release the received gas from the internal space to the outside.

[0091] According to the operation steps, the upper DC electrode 211 can release different gases. The gas released by the upper DC electrode 211 can be at least one selected from an inert gas, a reducing gas, and a heat source gas.

[0092] Without being limited thereto, the inert gas may include argon (Ar) gas, and the reducing gas and the heat source gas may respectively include at least one selected from hydrogen (H 2 ) gas, carbon dioxide (CO 2 ) gas, and methane (CH 4 ) gas.

[0093] The upper DC electrode 211 may include an electrode body 211a and a line fastening portion 211b coupled to each other. The line fastening portion 211b includes a thread that can be inserted into the electrode body 211a to couple the electrode body 211a and the line fastening portion 211b to each other.

[0094] However, the structure of the upper DC electrode 211 is not limited thereto. The upper portion of the electrode body 211 a may also be inserted into the line fastening portion 211 b and threadedly coupled thereto.

[0095] In essence, the electrode body 211a may receive power to generate arc heat. The line fastening portion 211b may connect the fourth gas supply pipe GP4 and the electrode body 211a and supply gas toward the electrode body 211a.

[0096] The upper DC electrode 211 may be provided with an internal pipe IP, a gas supply portion SP, and a gas discharge portion EM. The internal pipe IP may be provided by the electrode body portion 211 a and the line fastening portion 211 b.

[0097] The internal pipe IP can be provided to penetrate the upper DC electrode 211 along its length. The internal pipe IP can penetrate the electrode body 211a and the line fastening portion 211b, providing a space for gas flow. The internal pipe IP can extend along the length (Z-axis) of the upper DC electrode 211.

[0098] The gas supply portion SP may be located on one side of the inner tube IP in the Z-axis direction and receive gas from the fourth gas supply pipe GP4. The gas discharge portion EM may be located on the other side of the inner tube IP in the Z-axis direction and may discharge gas flowing through the inner tube IP to the outside of the upper DC electrode 211. The gas discharge portion EM may be located at the other end of the upper DC electrode 211 in the longitudinal direction (Z-axis direction).

[0099] In addition, refer to Figure 1 The preheating supply unit 220 can store the second iron source 2 and preheat the second iron source 2 before being charged into the second melting furnace 20. The preheating supply unit 220 can be a finger-type shaft furnace. In this case, the maintenance and operation of the preheating supply unit 220 can be made easier.

[0100] The preheat supply unit 220 can preheat the second iron source 2 stored therein using waste heat generated in the first melting furnace 10 or the second melting furnace 20. In this case, the waste heat can be supplied to the preheat supply unit 220 in the form of exhaust gas.

[0101] The preheat supply unit 220 may include a preheat chamber 221 and a chamber door 222 . The preheat supply unit 220 may be disposed above the second melting furnace 20 (on one side in the Z-axis direction, opposite to the direction of gravity). The second melting furnace 20, which is comprised of the second upper unit 200 and the lower unit 300 , may include the preheat supply unit 220 .

[0102] The preheating chamber 221 may extend in the Z-axis direction and may include a storage space for storing the second iron source 2. The preheating chamber 221 may have a cylindrical or polygonal shape. One or more loading doors for loading the second iron source 2 may be provided on the top or side of the preheating chamber 221.

[0103] The chamber door 222 may be disposed at the bottom of the preheating chamber 221 (the other side in the Z-axis direction, the direction of gravity) and may selectively open the bottom of the preheating chamber 221. Thus, the scrap stored in the preheating chamber 221 may be selectively supplied to the second melting furnace 20.

[0104] The opening and closing rate of the chamber door 222 can be adjusted, thereby selectively controlling the amount of scrap supplied to the interior of the second melting furnace 20 .

[0105] The partition unit 400 may be disposed between the first upper cell 100 and the second upper cell 200 and extend in the Z-axis direction. The partition unit 400 may be disposed between the first melting furnace 10 and the second melting furnace 20 .

[0106] The partition unit 400 may include refractory material so as to withstand the temperature of the molten bath or slag. The partition unit 400 may be combined with the first upper cell 100 and the second upper cell 200 so as to be replaceable.

[0107] The partition unit 400 may be raised and lowered, and may selectively separate the first lower space A1 - 2 of the first melting furnace 10 and the second lower space A2 - 2 of the second melting furnace 20 .

[0108] The partition unit 400 can separate the first slag 4a in the first furnace 10 and the second slag 4b in the second furnace 20. The first slag 4a may be a reducing slag based on ore-based iron sources (OBMs), and the second slag 4b may be an oxidizing slag based on waste.

[0109] Even if the first slag 4a and the second slag 4b have different properties, they can be separated from each other by the partition unit 400, thereby allowing them to be placed together in the double-layer melting furnace F without mixing. Furthermore, the functions of the heterogeneous first slag 4a and second slag 4b can be simultaneously utilized, thereby improving the efficiency of the entire operation process.

[0110] The exhaust duct 500 may be disposed outside the first upper cell 100 and the second upper cell 200 in the form of a duct, and may allow the first upper cell 100 and the second upper cell 200 to communicate with each other.

[0111] In other words, the exhaust duct 500 connects the first upper space A1-1 of the first melting furnace 10 and the second upper space A2-1 of the second melting furnace 20. The exhaust duct 500 supplies high-temperature exhaust gas generated in the first melting furnace 10 to the second melting furnace 20.

[0112] The gas low blowing device 600 can be disposed in the lower unit 300 to eject gas. A plurality of gas low blowing devices 600 can be provided. For example, a plurality of gas low blowing devices 600 can be disposed in the lower unit 300 that overlap with the first melting furnace 10 and the second melting furnace 20, respectively.

[0113] The gas sprayed from the low-gas blowing device 600 may include at least one of an inert gas or a heat source gas.

[0114] The low-pressure gas blowing device 600 can be used to control the flow of the molten metal 3 or to feed fuel and raw materials into the double-layer melting furnace F. The low-pressure gas blowing device 600 can be provided with at least one gas inlet, and the type, size, number, and location of the gas inlet can be varied as needed.

[0115] The tilting device 700 can tilt the electric furnace 1000 , thereby discharging the molten metal 3 , the first slag 4 a , the second slag 4 b , and the like inside to the outside.

[0116] The tilting device 700 may include a support cylinder 710 that maintains the center of the electric furnace 1000 and a drive cylinder 720 that can move up and down. A plurality of drive cylinders 720 may be provided. The support cylinder 710 and the drive cylinder 720 allow the electric furnace 1000 to be tilted in a direction intersecting the Z-axis direction.

[0117] Hereinafter, the electric furnace operating method of the present invention will be described.

[0118] Figure 3 This is a sequence diagram of an electric furnace operation method according to an embodiment.

[0119] Figures 4 to 9 sectional views of different process steps of an electric furnace operation method according to one embodiment.

[0120] Reference Figure 3 and Figure 4 First, an operating method of an electric furnace 1000 according to an embodiment may include steps S01 of melting a first iron source 1 and preheating a second iron source 2 .

[0121] Specifically, the first iron source 1 may be melted in the first melting furnace 10, and the second iron source 2 may be preheated in the second melting furnace 20. The melting of the first iron source 1 and the preheating of the second iron source 2 may be performed simultaneously.

[0122] The first melting furnace 10 can continuously receive and melt the first iron source 1 through a plurality of iron source supply units 120. The second melting furnace 20 can preheat the second iron source 2 while maintaining the second slag 4b in a foaming state.

[0123] The second iron source 2 can be preheated using waste heat generated by arcing in at least one of the first melting furnace 10 and the second melting furnace 20. For example, waste heat from the first melting furnace 10, which may be generated during the melting of the first iron source 1, can be supplied to the second melting furnace 20 along with exhaust gas through the exhaust duct 500, and can be used together with the waste heat from the second melting furnace 20 to preheat the second iron source 2.

[0124] The partition unit 400 may be lowered to the maximum extent to separate the first melting furnace 10 from the second melting furnace 20. In other words, the partition unit 400 may separate the first slag 4a from the second slag 4b.

[0125] In the step S01 of melting the first iron source 1 and preheating the second iron source 2 , the first electrode unit 110 may release the first gas G1 , and the second electrode unit 210 may release the second gas G2 .

[0126] The first gas G1 may include a reducing gas, but is not limited thereto. The reducing gas may include at least one selected from hydrogen (H 2 ) gas and methane (CH 4 ) gas.

[0127] The first iron source 1 may contain a large amount of iron oxide (FeO) and flow into the first melting furnace 10. When the first electrode 110 releases the first gas G1, even if a large amount of iron oxide (FeO) flows in, it can be easily reduced.

[0128] Furthermore, when arcing is performed in the first electrode unit 110, the reducing gas released from the first electrode unit 110 may be converted into plasma due to arc heat. The plasma-converted reducing gas can reduce activation energy and improve the efficiency of the reduction reaction.

[0129] When the first gas G1 contains reducing gas, at least a portion of the first electrode 110 may be immersed in the first slag 4a. The other end of the first electrode 110 in the Z-axis direction may be immersed in the first slag 4a.

[0130] Specifically, as shown in the upper DC electrode 211 (refer to Figure 2 ) of the gas release portion EM (refer to Figure 2 ), when the gas release parts of the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113 of the first electrode part 110 are immersed in the first slag 4a, the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113 can release the first gas G1.

[0131] When the gas release parts of the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113 are not immersed in the first slag 4a but are located outside the first slag 4a, the first AC electrode rod 111, the second AC electrode rod 112, and the third AC electrode rod 113 can release inert gas.

[0132] In this case, an inert gas atmosphere may be formed around the first AC electrode rod 111 , the second AC electrode rod 112 , and the third AC electrode rod 113 , thereby performing a function of sealing the area where the arc is generated.

[0133] That is, when the first AC electrode rod 111 , the second AC electrode rod 112 , and the third AC electrode rod 113 release the inert gas, it is possible to suppress or prevent nitrogen (N 2 ) in the air from being picked up by the molten metal 3 due to the arc flow.

[0134] The second gas G2 may include at least one selected from an inert gas and a reducing gas. However, the second gas G2 may include argon (Ar) gas and carbon dioxide (CO 2 ) gas, or may include methane (CH 4 ) gas.

[0135] While the first iron source 1 is being melted in the first melting furnace 10, impurities resulting from the melting of the first iron source 1 may flow into the second melting furnace 20. In this case, the impurities flowing into the second melting furnace 20 may be oxidatively refined by oxygen (O2).

[0136] The second gas G2 contains a reducing gas, thereby reducing the iron oxide (FeO) generated by the oxygen (O2) used in refining. Furthermore, the second gas G2 may contain an inert gas to control the balance between oxidative refining by the oxygen (O2) and the reduction of the iron oxide (FeO) generated by the oxidative refining.

[0137] Next, refer to Figure 3 、 Figure 5 and Figure 6 The operation method of the electric furnace 1000 may include steps S02 of melting the first iron source 1 and melting the second iron source 2 .

[0138] Specifically, the first iron source 1 can be melted in the first melting furnace 10, and the second iron source 2 can be melted in the second melting furnace 20. The melting of the first iron source 1 and the melting of the second iron source 2 can be performed simultaneously. The melting of the first iron source 1 can be continued while the second iron source 2 is preheated and melted.

[0139] As the first iron source 1 melts in the first melting furnace 10, the level of the molten metal 3 rises from level 1 to level 2. When the rising water level (level 2) reaches a level that completely submerges the second iron source 2, the chamber door 222 can be opened to allow the second iron source 2, preheated in the preheating chamber 221, to be loaded.

[0140] The preheated second iron source 2 is added according to the water level of the molten metal 3, thereby improving the melting efficiency of the second iron source. Furthermore, the second iron source 2 and the molten metal 3 are not covered by the second slag 4b, and the time they are exposed can be minimized, thereby suppressing or preventing the absorption of nitrogen (N) caused by the arc flow.

[0141] The partition unit 400 may be raised according to the level of the molten metal 3. Accordingly, the flow path of the molten metal 3 between the lower spaces A1-2 and A2-2 of the first melting furnace 10 and the second melting furnace 20 may be expanded.

[0142] As the flow channel expands, material exchange and heat exchange can be further activated. In addition, the first electrode portion 110 of the first melting furnace 10 and the second electrode portion 210 of the second melting furnace 20 can also rise according to the rising water level of the molten metal 3.

[0143] In the melting step S02 of the first iron source 1 and the melting step S03 of the second iron source 2, the first electrode 110 may release the first gas G1. According to the loading step of the second iron source 2, the second electrode 210 may release the third gas G3 different from the first gas G1 (see Figure 5 ) or the fourth gas G4 (refer to Figure 6 ).

[0144] Specifically, the melting step of the second iron source 2 may include an initial step of loading the second iron source 2 (see Figure 5 ) and loading later steps (refer to Figure 6 ).

[0145] In the initial step of charging the second iron source 2, the second slag 4b can be separated and dispersed by the second iron source 2 falling from the preheating chamber 221. Thus, the molten metal 3 and part of the second iron source 2 are not covered by the second slag 4b and can be exposed.

[0146] Furthermore, the upper DC electrode 211 may be exposed without being immersed in the second slag 4b and the molten metal 3. The end portion and the end of the upper DC electrode 211 on the other side in the Z-axis direction may be exposed. In this case, the gas release portion EM of the upper DC electrode 211 may be exposed without being immersed in the second slag 4b.

[0147] In this case, the second electrode portion 210 may release the third gas G3. The third gas G3 may include an inert gas. However, the present invention is not limited thereto. For example, the inert gas may include argon (Ar) gas.

[0148] The second electrode portion 210 may release the third gas G3 , and thus absorption of nitrogen (N) caused by the arc flow generated by the second electrode portion 210 may be suppressed or prevented.

[0149] In other words, the second electrode 210 can release the third gas G3, thereby forming a third gas G3 atmosphere in the space between the upper DC electrode 211 and the molten metal 3. The area around the arc can be formed into a third gas G3 atmosphere.

[0150] The arc flow generated between the upper DC electrode 211 and the lower DC electrode 212 may be sealed by the third gas G3 .

[0151] Thus, even if the upper DC electrode 211, the second iron source 2, and the molten metal 3 are not submerged in the second slag 4b and are exposed, it is possible to suppress or prevent nitrogen (N) from flowing into the molten metal 3 due to the arc flow.

[0152] For further details, refer to Figure 10 .

[0153] Figure 10 This is a graph showing the behavior of nitrogen in the different steps of the electric furnace operation method.

[0154] Further references Figure 10 , Figure 10 The graph has a horizontal axis and a vertical axis. The horizontal axis represents the progress (time) of the electric furnace operation process, and the vertical axis represents the nitrogen content (%).

[0155] Figure 10 The graph shows the behavior of nitrogen (N) when the iron source charged into the furnace includes scrap and direct reduced iron (DRI), and the ratio of scrap to direct reduced iron (DRI) is 1:4.

[0156] This can be applied to the operation process performed in the electric furnace 1000 of the present invention. However, this is only one example of the operation process that can be performed in the electric furnace 1000, and the present invention is not limited thereto.

[0157] exist Figure 10 In the graphs, graph X represents a case where the inert gas is not released in the electrode parts 110 and 210 , and graph Y represents a case where the inert gas is released in the electrode parts 110 and 210 to seal the arc flow.

[0158] According to the electric furnace operation process, Figure 10The diagram includes step A, step B, step C, step D, step E, step F, step G, step H and step I.

[0159] Step A is a step of heating the electrode parts 110 and 210 before melting the iron source in the furnace. In step A, it was confirmed that the nitrogen content (%) in the X graph and the Y graph was 0.0035%.

[0160] Step B is a step of melting the iron source by arc heat. In step B, it can be confirmed that the nitrogen content (%) increases in the X graph and the Y graph.

[0161] Step C is a step of forming slags 4a and 4b as melting proceeds. In step C, it can be confirmed that the nitrogen content (%) decreases in the X graph and the Y graph.

[0162] Step D is a step of heating the furnace to prepare for the decarburization process. In step D, it can be confirmed that the nitrogen content (%) in the X graph and the Y graph is maintained.

[0163] Step E is a step of performing a decarburization process. In step E, a decrease in the nitrogen content (%) can be confirmed in the X graph and the Y graph.

[0164] Step F is a step of adding a new iron source. In step F, it was confirmed that the nitrogen content (%) in the X graph and the Y graph was maintained.

[0165] Step G is a step of removing the cavity. In step G, it can be confirmed that the nitrogen content (%) increases in the X graph and the Y graph.

[0166] The H step is a step for storing the molten metal after leaving the cavity. In the H step, it can be confirmed that the nitrogen content (%) of the X graph and the Y graph is maintained.

[0167] Step I is a step of casting the molten metal. In step I, it can be confirmed that the nitrogen content (%) increases in the X graph and the Y graph.

[0168] Graph Y shows a relatively smaller increase in nitrogen content (%) in step B compared to Graph X. That is, as the electrode parts 110 and 210 release inert gas to seal the arc flow, nitrogen (N) absorption in step B can be suppressed and prevented.

[0169] Furthermore, when the absorption of nitrogen (N) is suppressed and prevented in step B, it can be confirmed that the graph Y can be moved to have a nitrogen content smaller than that of the graph X even if the subsequent steps are continued.

[0170] In addition, refer to Figure 3 and Figure 6In the late charging step where the second iron source 2 is completely immersed in the molten metal 3 , the second electrode portion 210 may release the fourth gas G4 .

[0171] When releasing the fourth gas G4, the other end portion and the end of the upper DC electrode 211 in the Z-axis direction can be immersed in the second slag 4b. That is, the gas release portion EM of the upper DC electrode 211 can be immersed in the second slag 4b.

[0172] The fourth gas G4 may include at least one of an inert gas and a reducing gas. The reducing gas may include at least one selected from the group consisting of carbon dioxide (CO 2 ) gas, hydrogen (H 2 ) gas, and methane (CH 4 ) gas.

[0173] For example, the fourth gas G4 may include argon (Ar) gas and carbon dioxide (CO 2 ) gas, or may include methane (CH 4 ) gas.

[0174] When the fourth gas G4 contains carbon dioxide (CO2) gas, the second slag 4b can be formed more smoothly. When the fourth gas G4 contains methane (CH4) gas or hydrogen (H2) gas, the iron oxide (FeO) generated by the melting of the second iron source 2 can be reduced more smoothly with oxygen.

[0175] Furthermore, when the fourth gas G4 further includes an inert gas, the balance between the melting performance and the reducing performance can be controlled by adjusting the concentration of the reducing gas.

[0176] Next, refer to Figure 3 and Figure 7 The operating method of the electric furnace 1000 may include step S03 of adjusting the grade of the first slag 4a.

[0177] Specifically, in the first melting furnace 10, the upper door 11a of the first slag door 11 can be opened upward, thereby allowing the first slag 4a to be discharged and the water level of the first slag 4a to be adjusted, thereby improving the efficiency of subsequent refining.

[0178] In the second melting furnace 20 , the second iron source 2 charged as the molten metal 3 may be continuously melted, or the new second iron source 2 supplied to the preheating supply part 220 may be preheated.

[0179] In this case, the partition unit 400 may also be raised according to the water level of the molten metal 3. Accordingly, the flow path of the molten metal 3 between the lower spaces A1-2 and A2-2 of the first melting furnace 10 and the second melting furnace 20 can be further expanded.

[0180] As the flow channel expands, material exchange and heat exchange can be further activated. In addition, the first electrode portion 110 of the first melting furnace 10 and the second electrode portion 210 of the second melting furnace 20 can also rise according to the rising water level of the molten metal 3.

[0181] Next, refer to Figure 3 and Figure 8 The operating method of the electric furnace 1000 may include a mixing and refining step S03 of the first slag 4a and the second slag 4b.

[0182] Specifically, the partition unit 400 may be raised to the maximum extent to maximize the opening between the first melting furnace 10 and the second melting furnace 20. Accordingly, the first slag 4a and the second slag 4b may be mixed to perform refining.

[0183] After adjusting the water level of the first slag 4a as the reducing slag, the first slag 4a and the second slag 4b are mixed, which can improve the refining efficiency. In addition, the partition unit 400 can be raised to the maximum to determine the surface where the refining reaction can occur, thereby further improving the refining efficiency.

[0184] After the first slag 4a and the second slag 4b are mixed, oxidative refining can be performed with oxygen (O2), thereby causing a rapid decarburization reaction and a dephosphorization reaction.

[0185] The first electrode unit 110 may release the fifth gas G5, and the second electrode unit 210 may release the sixth gas G6. The fifth gas G5 and the sixth gas G6 may each include a reducing gas.

[0186] For example, the reducing gas may include at least one selected from carbon dioxide (CO2) gas, methane (CH4) gas, and hydrogen (H2) gas. The fifth gas G5 and the sixth gas G6 may release the same type of gas, but are not limited thereto.

[0187] As the fifth and sixth gases G5 and G6 release reducing gases, the iron oxide (FeO) generated by the oxygen (O2) used for oxidative refining can be reduced. The concentration of the reducing gases released by the fifth and sixth gases G5 and G6 can be adjusted by taking into account the amount of oxygen (O2) input, refining capacity, and reducing capacity.

[0188] As the fifth gas G5 and the sixth gas G6 release reducing gases, the molten metal 3 can be refined and the iron oxide (FeO) reduced simultaneously. Furthermore, by adjusting the concentration of the reducing gas, the refining capacity and the reducing capacity can be adjusted simultaneously, thereby improving process efficiency.

[0189] go through Figures 4 to 8In the process, materials and heat can be exchanged between the first melting furnace 10 and the second melting furnace 20 through the area not separated by the partition unit 400. As a result, the refining reaction can be continuously carried out in the second melting furnace 20, and the maximum refining capacity can be ensured when the partition unit 400 is raised to the maximum.

[0190] Before the partition unit 400 rises to the maximum and mixes the first slag 4a and the second slag 4b, the first melting furnace 10 may maintain the first slag 4a, thereby reducing a large amount of iron oxide (FeO) flowing from the first iron source 1.

[0191] Next, refer to Figure 3 and Figure 9 The operating method of the electric furnace 1000 may include step S05 of discharging the molten metal 3 .

[0192] Specifically, by raising the driving cylinder 720 on the second melting furnace 20 side, the double-layer melting furnace F can be tilted. The double-layer melting furnace F can be tilted toward the first melting furnace 10 where the cavity outlet 310 is formed.

[0193] Thus, the molten metal 3 and / or slag 4 in the first melting furnace 10 and the second melting furnace 20 can be discharged more smoothly. The slag 4 may be a mixture of the first slag 4a and the second slag 4b.

[0194] The preheat supply part 220 may be formed in a form that can be separated from the remaining portion of the second upper unit 200. In this case, the double-layer furnace F can be tilted more smoothly.

[0195] The electric furnace 1000 includes a first melting furnace 10 and a second melting furnace 20 for melting different first iron sources 1 and second iron sources 2, thereby ensuring productivity, economy and quality, and embodying carbon neutrality in steel production.

[0196] Ore-based iron sources (OBMs), low-grained waste, and general waste are fed into the respective furnaces 10 and 20 in parallel, and the respective slags 4a and 4b are separated, thereby melting the main raw materials and performing refining.

[0197] The operating influence caused by the large amount of gangue that may flow from the ore-based iron source (OBM) can be separated and discharged from the first melting furnace 10, thereby maintaining and managing appropriate refining conditions. In addition, a large amount of ore-based iron source (OBM) can be charged into the first melting furnace 10, thereby reducing the tramp component.

[0198] Furthermore, waste can be fed into and operated through the second melting furnace 20 connected to the first melting furnace 10, thereby achieving a complete flat bath operation.

[0199] The simultaneous operation of the first melting furnace 10 and the second melting furnace 20 and the preheating of the second iron source 2 of the second melting furnace 20 can reduce energy consumption to below the level of ordinary scrap operation and shorten the operation to the level of a converter.

[0200] The first electrode portion 110 and the second electrode portion 210 release reducing gas to reduce the slags 4 a and 4 b , thereby improving the recovery rate of molten steel.

[0201] Table 1

[0202]

[0203]

[0204] In Table 1, the first operation represents a case where the iron source melted in the furnace is 100% scrap, while the second operation represents a case where the iron source melted in the furnace includes scrap and direct-reduced iron (HBI). The second operation can be substantially the same as the operation of the electric furnace 1000 of this embodiment.

[0205] The iron source used in the second operation includes scrap and direct reduced iron (HBI) at a ratio of 4:6, but the ratio of scrap and direct reduced iron (HBI) is not limited thereto.

[0206] The contents described in Table 1 are merely examples of each of the first operation and the second operation, and the operations are not limited thereto.

[0207] The loading volume of the first operation is 168.8 tons, the discharge volume is 152 tons, the unit of quicklime raw material is 18.2kg / ton, the unit of light raw material is 13.4kg / ton, the CaO input amount is 3,029kg, the total iron content in the slag is 16.28%, and the theoretical slag production is 17,937kg.

[0208] The loading capacity of the second operation is 168.1 tons, the cavity discharge capacity is 149 tons, the unit of quicklime raw material is 28.2kg / ton, the unit of light raw material is 9.5kg / ton, the CaO input is 3,940kg, the total iron content in the slag is 23.75%, and the theoretical slag production is 22,270kg.

[0209] The molten steel recovery rate can be expressed by the following formula 1.

[0210] Formula 1

[0211] Molten steel recovery rate (%) = (outlet volume / charge volume) × 100 (%)

[0212] The molten steel recovery rate (%) can be calculated by multiplying the value obtained by dividing the discharge volume by the charge volume by 100.

[0213] The molten steel recovery rate (%) for the first operation is (152 / 168.8) × 100 = 90.0%. The molten steel recovery rate (%) for the second operation is (149 / 168.1) × 100 = 88.6%. However, if the electrode parts 110 and 210 release reducing gas to reduce the slag 4a and 4b, the molten steel recovery rate for the second operation can be improved.

[0214] The additional molten steel recovery rate of the second operation can be expressed by the following formula 2.

[0215] Formula 2

[0216] Additional molten steel recovery rate (%) = (theoretical slag production (kg) × reduction in total iron content) / charging amount (kg) × 100 (%)

[0217] The additional molten steel recovery rate (%) can be calculated by multiplying the value of the theoretical slag production and the reduction in the total iron content by the charge amount and multiplying the result by 100.

[0218] The slags 4 a and 4 b can be reduced by the reducing gas released through the electrode parts 110 and 210 , and the total amount of iron in the slags 4 a and 4 b can be reduced.

[0219] For example, when the total iron content of the second operation is reduced to 16.28% of the total iron content of the first operation, the reduction in the total iron content in Formula 2 is 23.75%-16.28%=7.47%.

[0220] In this case, the additional molten steel recovery rate of the second operation is (22,270 (kg) × 7.47 (%)) / 168100 (kg) = 0.98 (%).

[0221] In the case of the second operation, the total molten steel recovery rate is 88.6% + 0.98% = 89.58%.

[0222] As the slags 4a and 4b are reduced by the reducing gas released by the electrode parts 110 and 210, a molten steel recovery rate corresponding to that of an operation using only scrap can be ensured even when scrap and direct reduced iron are used as iron sources.

[0223] Furthermore, in the case of the second operation, the amount of scrap input is smaller than that of the first operation, so that high-quality molten steel with a significantly low content of residual elements can be produced.

[0224] In the following embodiments, for the same structures as those previously described, repeated descriptions will be omitted or simplified, and the differences will be mainly described.

[0225] Figure 11 This is a sequence diagram of an electric furnace operation method according to another embodiment. Figure 12 and Figure 13 for Figure 11 Cross-sectional views of different process steps of the electric furnace operation method according to an embodiment.

[0226] Reference Figure 11 and Figure 12 , the electric furnace 1000_1 of another embodiment is composed of a single melting furnace, rather than a double-layer melting furnace F (refer to Figure 1 ) structure, which is different from one embodiment in this respect.

[0227] Furthermore, the operating method of the electric furnace 1000_1 of another embodiment includes step S01_1 of adding iron source 1_1, step S02_1 of melting the iron source 1_1, step S03_1 of refining, and step S04_1 of removing the iron from the furnace, which is different from the first embodiment.

[0228] Specifically, the electric furnace 1000_1 may include an upper cell 100_1 , a lower cell 300_1 , a melting furnace 10_1 composed of the upper cell 100_1 and the lower cell 300_1 , and an electrode part 110_1 .

[0229] The electrode unit 110_1 includes a first AC electrode rod 111_1, a second AC electrode rod 112_1, and a third AC electrode rod 113_1, each of which is connected to a first gas supply pipe GP1, a second gas supply pipe GP2, and a third gas supply pipe GP3, and receives multiple gases from a gas storage tank GS.

[0230] In step S01_1 of adding the iron source 1_1, the iron source 1_1 is added into the furnace 10_1. The iron source 1_1 may include scrap, but is not limited thereto. The iron source 1_1 may fill the entire volume of the furnace 10_1.

[0231] In step S02_1 of melting the iron source 1_1, the electrode unit 110_1 may receive power to generate arc heat, and the iron source 1_1 may be melted inside the furnace 10_1 by the generated arc heat.

[0232] The electrode portion 110_1 may release a seventh gas G7. The seventh gas G7 may include an inert gas. The inert gas may include, for example, argon (Ar) gas, but is not limited thereto.

[0233] The electrode portion 110_1 may not be immersed in the slag 4_1 and the molten metal 3_1 but may be exposed. The end portion and the end of the electrode portion 110_1 on the other side in the Z-axis direction may be exposed. In this case, the gas release portion EM of the electrode portion 110_1 (see Figure 2 ) can be exposed without being immersed in the slag 4_1.

[0234] As the electrode portion 110_1 releases the seventh gas G7, an inert gas atmosphere may be formed around the electrode portion 110_1. Thus, even if an arc is generated in the electrode portion 110_1, the inert gas atmosphere may be formed around the arc, thereby suppressing or preventing nitrogen (N) absorption.

[0235] Reference Figure 11 and Figure 13 , iron source 1_1 (refer to Figure 12 ) is melted to form molten metal 3_1 and slag 4_1. In the electrode portion 110_1, the periphery where the arc is generated can be sealed by the molten metal 3_1.

[0236] In the refining step S03_1 , oxygen gas may be blown into the interior of the melting furnace 10_1 to perform oxidation refining on the molten metal 3_1 .

[0237] The electrode portion 110_1 may release an eighth gas G8. The eighth gas G8 may include a reducing gas. For example, the reducing gas may include at least one selected from carbon dioxide (CO2) gas, hydrogen (H2) gas, and methane (CH4) gas, but is not limited thereto.

[0238] At least a portion of the electrode portion 110_1 may be immersed in the interior of the slag 4_1. The end portion and the end portion on the other side of the Z-axis direction of the electrode portion 110_1 may be immersed in the interior of the slag 4_1. In this case, the gas release portion EM (see Figure 2 ) can be immersed in the slag 4_1.

[0239] As the electrode unit 110_1 releases the eighth gas G8, the iron oxide (FeO) produced by the oxidative refining process can be reduced. The reducing gas can be converted into plasma, thereby increasing the efficiency of the reduction reaction. This can improve the efficiency of the entire process.

[0240] In the cavity discharge step S04_1 , when the condition of the molten metal 3_1 corresponds to the target condition, the molten metal 3_1 may be discharged from the electric furnace 1000_1 by the moving mechanism.

[0241] In this case, the electrode part 110_1 also releases different gases in different working steps, thereby improving working efficiency and product quality.

[0242] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it will be understood by those skilled in the art that the present invention can be implemented in other specific forms without changing the technical concept or essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and are not restrictive.

[0243] Description of Reference Signs

[0244] 1: First iron source

[0245] 2: Second iron source

[0246] 3: Molten Metal

[0247] 4: Slag

[0248] 10: The First Furnace

[0249] 20: Second Furnace

[0250] 100: First upper monomer

[0251] 110: First electrode portion

[0252] 200: Second upper monomer

[0253] 210: Second electrode portion

[0254] 220: Preheating supply unit

[0255] 300: Lower monomer

[0256] 400: Partition unit

[0257] 500: Exhaust pipe

[0258] 600: Gas low blowing device

[0259] 700: Tilt device

[0260] 1000: Electric furnace

Claims

1. An electric furnace operation method, characterized in that: include: a step of melting a first iron source in a first melting furnace provided with a first electrode portion; preheating a second iron source in a second melting furnace provided with a second electrode portion; and a step of melting the second iron source in the second melting furnace, The first melting furnace and the second melting furnace share an inner space, In the step of preheating the second iron source, the second electrode portion releases the first gas, In the step of melting the second iron source, the second electrode portion releases a second gas different from the first gas.

2. The electric furnace operation method according to claim 1, characterized in that: The first gas includes a reducing gas, and the second gas includes an inert gas.

3. The electric furnace operation method according to claim 2, characterized in that: The reducing gas comprises at least one selected from carbon dioxide (CO2) gas, methane (CH4) gas and hydrogen (H2) gas, The inert gas includes argon (Ar) gas.

4. The electric furnace operation method according to claim 2, characterized in that: The first gas further comprises an inert gas.

5. The electric furnace operation method according to claim 1, characterized in that: The step of melting the second iron source includes an initial melting step and a late melting step. In the initial melting step, the second electrode portion releases the second gas. In the late melting step, the second electrode portion releases a third gas different from the second gas.

6. The electric furnace operation method according to claim 5, characterized in that: The second gas includes an inert gas, and the third gas includes a reducing gas.

7. The electric furnace operation method according to claim 6, characterized in that: In the initial melting step, the second electrode portion is exposed to the outside. In the late melting step, at least a portion of the second electrode portion is immersed in the slag.

8. The electric furnace operation method according to claim 1, characterized in that: The step of melting the first iron source, the step of preheating the second iron source, and the step of melting the second iron source are performed simultaneously.

9. The electric furnace operation method according to claim 8, characterized in that: In the step of melting the first iron source, the first electrode portion releases a third gas.

10. The electric furnace operation method according to claim 9, characterized in that: The third gas includes a reducing gas.

11. The electric furnace operation method according to claim 1, characterized in that: The method further includes mixing the first slag in the first melting furnace and the second slag in the second melting furnace, and refining the molten metal. In the step of refining the molten metal, the first electrode portion releases a third gas, and the second electrode portion releases a fourth gas. The third gas and the fourth gas include reducing gases.

12. The electric furnace operation method according to claim 1, characterized in that: The first electrode portion includes a first AC electrode rod, a second AC electrode rod, and a third AC electrode rod. The second electrode portion includes an upper DC electrode and a lower DC electrode.

13. The electric furnace operation method according to claim 12, characterized in that: The upper DC electrode comprises: an inner tube, which is provided to penetrate the upper DC electrode in a longitudinal direction and allows at least one of the first gas and the second gas to flow; a gas supply portion located on one side of the inner tube to supply at least one of the first gas and the second gas; and The gas release portion is located at the other side of the inner tube and is used to release at least one of the first gas and the second gas.

14. The electric furnace operation method according to claim 12, characterized in that: The first iron source comprises an ore-based iron source and the second iron source comprises scrap.

15. An electric furnace operation method, characterized in that: include: a step of feeding an iron source into the interior of the electric furnace including the electrode portion; applying power to the electrode portion to melt the iron source; as well as Blowing oxygen into the electric furnace and performing the refining step, In the step of melting the iron source, the electrode portion releases a first gas, In the step of performing the refining, the electrode portion releases a second gas different from the first gas.

16. The electric furnace operation method according to claim 15, characterized in that: The first gas comprises an inert gas, The second gas comprises a reducing gas.

17. The electric furnace operation method according to claim 15, characterized in that: The electrode portion includes a first AC electrode rod, a second AC electrode rod, and a third AC electrode rod.

18. The electric furnace operation method according to claim 17, characterized in that: The first AC electrode rod, the second AC electrode rod, and the third AC electrode rod respectively release at least one of the first gas and the second gas from the inside.

19. An electric furnace operation method comprising an electrode rod having a space therein for accommodating at least one of an iron source, a fusible wire, and slag, wherein: The electrode rod releases a first gas containing an inert gas; and The electrode rod releases a second gas containing a reducing gas, In the step of releasing the first gas, one end of the electrode rod is exposed. In the step of releasing the second gas, the one end of the electrode rod is located inside the slag.

20. The electric furnace operation method according to claim 19, characterized in that: The electrode rod comprises: an inner tube in which the first gas and the second gas flow; and a gas release portion, located on one side of the inner tube, and releasing the first gas and the second gas; The gas release portion is disposed at the one end of the electrode rod.

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