Electric furnace

Abstract

The invention relates to an electric furnace with a double-type melting furnace. The electric furnace may include: a first upper unit forming a first upper space of a first melting furnace into which a first iron source is input and melted; a second upper unit forming a second upper space of a second melting furnace for inputting and melting a second iron source; a lower unit coupled to the lower portions of the first upper unit and the second upper unit such that a first lower space of the first melting furnace and a second lower space of the second melting furnace can be formed into one integrated space; and a bulkhead unit installed between the first upper unit and the second upper unit to be vertically movable so as to separate a first lower space of the first melting furnace and a second lower space of the second melting furnace, which are integrated by means of the lower unit.

Description

Technical Field

[0001] The present invention relates to an electric furnace, and more particularly, to an electric furnace provided with a dual type melting furnace, into which ore based materials (OBM), low-grained waste and general waste are simultaneously introduced, wherein gangue components input in large quantities from the OBM can be effectively separated without being mixed with existing slag, while a main raw material is melted and refined. Background Art

[0002] Generally, in the iron and steel metallurgical industry, the production process of steel materials can be roughly divided into a "blast furnace-converter" production system (hereinafter referred to as "converter") that uses ore as the main raw material and an "electric furnace" production system that recovers / recycles waste materials after manufacturing products using the produced steel materials.

[0003] The converter system is widely used to produce high-quality products, mainly steel sheets or plates that are sensitive to surface defects, based on the initial state of molten steel from ore. On the other hand, the electric furnace system using scrap (the scrap may be affected by impurities (Cu, Sn, Cr, Mo, Ni, etc., hereinafter referred to as included elements) added during the production of the final product or mixed during the recycling process) is generally applied to the production of bars / profiles that mainly require high strength. However, if specific requirements are met, in some cases, steel sheets or plates are produced by utilizing the electric furnace process. In addition, as carbon neutrality becomes a global issue, the electric furnace process, which produces a carbon dioxide (CO2) level of ≤20% compared to the converter process, is currently becoming an alternative for the future steelmaking industry (steel sheet production).

[0004] In this regard, the process disruption factors associated with the production of high-quality steel sheets using the electric furnace process can be divided into the main raw material (scrap) and problems caused by the characteristics of the melting process.

[0005] The former, i.e. the main raw material, is the cause of surface defects in the product. Specifically, for steel sheet products that only apply mechanical processing in a single axial direction when surface electroplating is performed, surface defects caused by the inclusion elements input from the scrap during the continuous casting process tend to become more serious when passing through the rolling process, and the processability may also deteriorate. Secondly, due to the characteristics of the scrap melting process using an arc (electric energy), there is a phenomenon that nitrogen (N2) in the air around the electrode is ionized (plasma) and flows into the molten steel through the arc flow. In addition, the nitrogen accumulated in the scrap itself (nitrogen absorbed in the production step) also generally shows a higher [N] ppm level than the converter process. Specifically, the [N] ppm level is generally ≥80ppm, which is much higher than the ≥15ppm in the converter. This indicates that the quality of the molten steel does not meet the composition specifications of high-grade steel sheets with a level of ≤30ppm.

[0006] In order to overcome such limitations as mentioned above, the widespread or active use of ore-based materials (OBM: ore-based materials) (such as DRI, HBI, PI, GPI, etc.) is considered to be an ideal alternative. As a representative example, DRI / HBI produces iron sources by directly performing a reducing reaction by processing ore into pellets and reacting it with a reducing gas, unlike a blast furnace. At present, more and more electric furnace steelmaking companies are manufacturing steel sheets by applying existing devices. Since the above-mentioned materials are ore-based raw materials (the composition is similar to that used in blast furnaces), when applied to electric furnaces, they have the advantage of controlling the initial properties of molten steel (i.e., the input level of intercalated elements) according to the mixing ratio. On the contrary, in the case of large-scale application (application of a high mixing ratio: ≥30%), it cannot be introduced by "batch charging" (a typical main raw material charging method in an electric furnace), but the disadvantage is that a separate feeding device such as "continuous top charging" is required. However, as the OBM mixing ratio increases, the scrap melting process that is susceptible to nitrogen inflow is shortened (becomes a flat batch), thereby achieving the effect of reducing the [N] level in molten steel.

[0007] In order to manufacture high-quality steel for automobile outer panels or similar products, it is necessary to apply the DRI / HBI mixing ratio (≥80%) to a level similar to the hot metal ratio (HMR) of the converter currently used in the art. However, with regard to existing devices and technologies, there are limitations (increased energy consumption, reduced productivity, etc.) in increasing the above mixing ratio, and therefore it is necessary to develop a new device and technology to overcome the above limitations. Summary of the invention

[0008] Technical issues to be resolved

[0009] DRI / HBI is produced by direct gas reduction, so gangue components (SiO2, Al2O3, etc.) contained in the ore are mixed in the raw materials, which brings about the problem that all components must be completely removed in the electric furnace. This is different from the case of a blast furnace, where the gangue components are separated / removed when the molten iron produced in the blast furnace is converted from the solid phase (ore) to the liquid phase (molten iron). In addition, since the input level of the [P] component is much higher than that of the waste material, and the slag basicity (or alkalinity) (C / S) is greatly reduced due to the gangue components, the amount of slag-making agent introduced for refining increases, causing a problem of exponentially increasing the amount of slag generated.

[0010] In addition, due to the characteristics of the direct gas reduction method, the reduction reaction is somewhat disadvantageous compared with the blast furnace process, and the FeO content in the raw material is generally high (5% to 8%). Therefore, there is a problem that the reduction process must be carried out to the maximum extent in the electric furnace where the oxidation process is carried out (increasing the consumption of energy and reducing agent). Therefore, as the mixing ratio increases, the working performance or operation results such as the increase in the amount of slag-making agent, the increase in power consumption, the decrease in molten steel recovery rate, the decrease in productivity, etc., are drastically deteriorated, and cost competitiveness may be reduced.

[0011] Therefore, when a conventional and generally compatible electric furnace is operated only with a dedicated introduction device, there is a problem that the DRI / HBI mix ratio is limited to a maximum level of 30% when producing typical sheets or plates (structural materials).

[0012] The present invention is intended to solve various problems including the above problems, and an object of the present invention is to provide an electric furnace that can variably control the mixing ratio of DRI / HBI (including other OBM) from 0 to 100% according to the type of sheet to be produced, while ensuring operation stability and economic advantages corresponding to a high mixing ratio. However, this object is only illustrative, and the scope of the present invention is not limited thereto.

[0013] Technical Solution

[0014] According to an embodiment of the present invention, an electric furnace is provided. The electric furnace may be provided with a dual-type melting furnace, wherein the dual-type melting furnace includes two melting furnaces and the two melting furnaces are at least partially combined together, and the electric furnace includes: a first upper unit, the first upper unit forms a first upper space of a first melting furnace for introducing and melting a first iron source; a second upper unit, the second upper unit is arranged in a horizontal direction of the first upper unit and forms a second upper space of a second melting furnace for introducing and melting a second iron source; a lower unit, the lower unit is combined with the lower part of the first upper unit and the second upper unit and forms a single integrated space integrating the first lower space of the first melting furnace and the second lower space of the second melting furnace; and a partition unit, the partition unit is installed to move vertically up and down between the first upper unit and the second upper unit, and separates the first lower space of the first melting furnace and the second lower space of the second melting furnace, although the two lower spaces are formed integrally by the lower unit.

[0015] According to an embodiment of the present invention, the first upper unit may have a furnace wall formed of a refractory material, so that the melting furnace has a refractory structure.

[0016] According to an embodiment of the present invention, the first upper unit may include: a first electrode member, at least a portion of which is inserted into the first upper space of the first melting furnace through a small ceiling of a first furnace roof portion formed at the top of the first upper unit and melts the first iron source using arc heat; and a plurality of iron source feeders, which are radially arranged around the center of the first electrode member and supply the first iron source through the first upper space of the first melting furnace.

[0017] According to an embodiment of the present invention, the first electrode member may include a plurality of alternating current (AC) electrodes radially arranged around the center of the small ceiling of the first furnace top portion, and a plurality of iron source feeders may respectively continuously supply the first iron source toward the ignition points of the respective AC electrodes corresponding to the respective iron source feeders.

[0018] According to an embodiment of the present invention, the second upper unit may include: a second electrode member, at least a portion of which is inserted into the second upper space of the second melting furnace through a small ceiling of a second furnace roof portion formed at the top of the second upper unit and melts the second iron source by arc heat; and a preheating feeder, which is installed on one side of the second electrode member at the top of the second upper unit, temporarily stores a predetermined amount of the second iron source in a storage space inside the preheating feeder, and uses waste heat generated inside the second melting furnace to preheat the second iron source temporarily stored in the above-mentioned storage space, and then supplies the second iron source through the second upper space of the second melting furnace.

[0019] According to an embodiment of the present invention, the second electrode member may include: an upper direct current (DC) electrode, which is inserted through a small ceiling of the second furnace top part and is arranged on the second upper space side of the second melting furnace; and a lower DC electrode, which is installed at the bottom of the lower unit to face the upper DC electrode in a vertical direction and is arranged on the second lower space side of the second melting furnace.

[0020] According to an embodiment of the present invention, the lower DC electrode may include a first lower electrode whose central axis is formed at the bottom of the lower unit to be coaxial with the central axis of the upper DC electrode so that the lower DC electrode may directly face the upper DC electrode.

[0021] According to an embodiment of the present invention, the lower DC electrode may further include a second lower electrode, the central axis of which is formed to be inclined at a predetermined angle relative to the central axis of the upper DC electrode at the bottom of the lower unit, thereby being biased toward the preheating feeder relative to the upper DC electrode, so that the lower DC electrode can face the upper DC electrode in the inclined direction.

[0022] According to an embodiment of the present invention, the second electrode member can induce current between the upper DC electrode and the second lower electrode immediately after the preheating feeder supplies the second iron source, and induce current between the upper DC electrode and the first lower electrode after the second iron source is completely melted.

[0023] According to an embodiment of the present invention, the volume of the first melting furnace consisting of the first upper space of the first upper unit and the first lower space of the lower unit may be smaller than the volume of the second melting furnace consisting of the second upper space of the second upper unit and the second lower space of the lower unit.

[0024] According to an embodiment of the present invention, in order to connect the first upper space of the first melting furnace and the second upper space of the second melting furnace, the electric furnace of the present invention may further include a waste gas duct, which connects the first upper unit and the second upper unit in the form of a duct and supplies the waste heat generated in the first melting furnace toward the second melting furnace.

[0025] According to an embodiment of the present invention, the first melting furnace may include a first slag door, which is arranged at a boundary portion between the first upper unit and the lower unit and is configured in a double door form, including an upward-opening upper door and a downward-opening lower door facing each other in a vertical direction, so that the slag generated in the first melting furnace can be selectively discharged.

[0026] According to an embodiment of the present invention, the first melting furnace may open the upper door during operation to maintain the slag height in the first melting furnace at a predetermined level, and open the lower door when discharging (or discharging) the slag in the first melting furnace.

[0027] According to an embodiment of the present invention, the second melting furnace may include a second slag door, which is arranged at a boundary portion between the second upper unit and the lower unit and is configured in the form of a single door that opens upward or downward, so that the slag generated in the second melting furnace can be selectively discharged.

[0028] According to an embodiment of the present invention, in order to control the flow of molten metal between the first melting furnace and the second melting furnace, the electric furnace of the present invention may further include a bottom blowing device which is arranged at the bottom of the lower unit and provided with a plurality of plugs for discharging gas.

[0029] According to an embodiment of the present invention, the lower unit can be provided with a discharge port at a position corresponding to the first electrode member (the first electrode member is installed on a small ceiling of the first furnace top part formed on the top of the first upper unit) on the floor surface forming the first lower space to discharge the molten metal in the dual-type melting furnace.

[0030] According to an embodiment of the present invention, in the lower unit, a floor surface forming the first lower space (in which the discharge port is formed) may be higher than a floor surface forming the second lower space.

[0031] According to an embodiment of the present invention, the electric furnace of the present invention may further include a tilting device, which can tilt the dual-type melting furnace that at least partially combines the first melting furnace and the second melting furnace in a horizontal direction, or can tilt the dual-type melting furnace in a horizontal direction and a width direction perpendicular to the vertical direction.

[0032] According to an embodiment of the present invention, the tilting device may include: a supporting cylinder for maintaining the center of the double-type melting furnace tilted by the tilting device, and supporting the double-type melting furnace, while possibly tilting the double-type melting furnace; and a plurality of driving cylinders, specifically, at least three driving cylinders, which are radially arranged around the supporting cylinder to support the double-type melting furnace at at least three points, and can be driven upward and downward individually to selectively tilt the double-type melting furnace along the above-mentioned horizontal direction or width direction.

[0033] According to an embodiment of the present invention, the tilting device can tilt the double-type melting furnace in a horizontal direction, so that when discharging molten metal in the double-type melting furnace, the double-type melting furnace can be tilted in the direction of the first melting furnace (wherein a discharge port is formed); on the other hand, when discharging slag in the first melting furnace or the slag in the second melting furnace, the tilting device can tilt the double-type melting furnace in the above-mentioned width direction, so that the double-type melting furnace can be tilted in the direction of the first slag door in the first melting furnace and in the direction of the second slag door in the second melting furnace.

[0034] According to an embodiment of the present invention, the preheating feeder may include: a preheating chamber, which is formed in a cylindrical shape or a polygonal column shape to extend in the vertical direction to form a finger-type column furnace; and a chamber door, which is installed on the lower side of the open preheating chamber to selectively open the lower side of the preheating chamber.

[0035] According to an embodiment of the present invention, the first iron source introduced into the first melting furnace may include ore based material (OBM), and the second iron source introduced into the second melting furnace may include scrap.

[0036] Effects of the Invention

[0037] According to the embodiment of the present invention configured as above, which basically involves the simultaneous introduction of OBM and low-particle size scrap and general scrap, the gangue components input in large quantities from the OBM can be effectively separated to prevent them from mixing with the existing slag (the gangue containing SiO2 and Al2O3 as main components is mainly used as acidic slag, and if the input amount is large, it may become a cause of introducing a large amount of CaO to refine / remove the P component in molten steel. Therefore, the increase in the slag-making agent source unit and the large amount of slag produced thereby may become the main factors of uneconomic structures such as reduced molten steel recovery rate, increased energy consumption, and extended operating time), thereby realizing a dual-type melting furnace capable of simultaneously melting the main raw materials and refining.

[0038] Therefore, in order to transform the traditional "blast furnace-converter" production system into an "electric furnace" production system, the present invention relates to a new concept of a melting method using an electric furnace, which introduces a large amount of ore-based iron source (represented by DRI) while ensuring the same or higher productivity / economic advantages / quality as the traditional "blast furnace-converter" production system, wherein a new electric furnace capable of using a large amount of OBM is adopted, thereby achieving the effect of carbon neutrality in the steelmaking industry.

[0039] For example, when applying the electric furnace with a dual-type melting furnace configuration according to the present invention, by effectively separating and discharging gangue from the first melting furnace, the influence of gangue input in large quantities from DRI on the working and optimal refining conditions can be maintained / managed; DRI can be efficiently applied in large quantities using the first melting furnace for only OBM, thereby reducing the inclusion components; according to the process of introducing / operating the scrap through the first melting furnace (OBM is continuously charged in the first melting furnace), and the second melting furnace is connected to the first melting furnace in the form of a dual-type structure, a perfect flat bath operation can be performed; due to the exhaust gas duct structure, nitrogen pickup can be effectively blocked by arc sealing, thereby ensuring the N output level of the converter. In addition, the high energy concentration structure of the first melting furnace, the preheating of the scrap in the second melting furnace using the exhaust gas, and the simultaneous operation of the first melting furnace and the second melting furnace can realize an electric furnace capable of reducing energy consumption to a general scrap working level or lower, and shortening the operating time to the converter level. Of course, the scope of the present invention is not particularly limited to such effects as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a cross-sectional view schematically showing an electric furnace according to an embodiment of the present invention.

[0041] Figure 2 To schematically illustrate the Figure 1 A cross-sectional view of a cross section of an electric furnace taken along cutting line AA is shown.

[0042] Figure 3 To schematically illustrate the Figure 1 A cross-sectional view of a cross section of an electric furnace taken along cutting line BB is shown.

[0043] Figures 4 to 7 To schematically illustrate the steps Figure 1 A cross-sectional view showing the operation process of an electric furnace is shown.

[0044] Figure 8 and Fig. 9 To schematically illustrate Figure 1 A cross-sectional view of the tilting process of the electric furnace is shown.

[0045] Fig.10 and Fig.11 : is a table showing the comparison results between the operating results when using a conventional electric furnace and the expected operating indicators when using the electric furnace of the present invention. DETAILED DESCRIPTION

[0046] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0047] The embodiments of the present invention are provided to explain the present invention more comprehensively to persons with common knowledge of the field to which the present invention belongs ("those skilled in the art"). The following embodiments may be modified into various forms, and the scope of the present invention is certainly not limited thereto. On the contrary, these embodiments are provided to make this specification more complete and perfect, and to perfectly convey the spirit of the present invention to those skilled in the art. In addition, for the convenience and clarity of explanation, the thickness or size of each layer shown in the figure may be exaggerated.

[0048] Embodiments of the present invention will be described below with reference to the accompanying drawings that schematically illustrate ideal examples of the present invention. For example, in the accompanying drawings, variations in the illustrated form may be predicted based on manufacturing techniques and / or tolerances. Therefore, embodiments based on the spirit of the present invention should not be interpreted as being limited to the specific shapes of the regions described in this specification, and, for example, variations in shape caused by the manufacturing process should be included.

[0049] Figure 1 Schematically showing a cross-sectional view of an electric furnace 1000 according to an embodiment of the present invention; Figure 2 To schematically illustrate the Figure 1 A cross-sectional view of a section of the electric furnace 1000 taken along the dashed line AA shown; Figure 3 To schematically illustrate the Figure 1 A cross-sectional view of a section of the electric furnace 1000 taken along the dashed line BB shown; Figures 4 to 7 To schematically illustrate the steps Figure 1 A cross-sectional view of the operation process of the electric furnace 1000 is shown; Figure 8 and Fig. 9 To schematically illustrate Figure 1 A cross-sectional view showing the tilting process of the electric furnace; and Fig.10 and Fig.11 : is a table showing the comparison results between the operating results when using a conventional electric furnace and the expected operating indicators when using the electric furnace of the present invention.

[0050] First, if Figure 1 As shown, the electric furnace 1000 according to the embodiment of the present invention may be an electric furnace provided with a dual-type melting furnace F, in which two melting furnaces 10 and 20 are arranged in a horizontal direction (X-axis direction) and at least partially combined to melt different iron sources.

[0051] For example, the first melting furnace 10 in the dual type melting furnace F can melt the first iron source ( Figure 4 ), the first iron source mainly includes ore-based materials (OBM) (DRI, HBI, PI, GPI, etc.), and in addition, may also include some low-granularity waste (shredder, feed line, etc.), wherein the furnace may have a structure for performing continuous melting by applying energy synchronously controlled with the introduction rate of the first iron source 1 continuously introduced through the ceiling (at this energy level, the melting energy for the first iron source 1 and the molten metal in the furnace ( Figure 4 The temperature shown in "3") can be maintained at the desired level).

[0052] Regarding the first melting furnace 10, in view of the above-mentioned melting characteristics, the first iron source 1 is not stacked in the furnace and the furnace does not require a large space. Therefore, the internal volume of the furnace can be limited to a minimum level sufficient not to damage the outer wall due to the arc generated in the electrode (that is, a compact furnace with a smaller volume compared to the second melting furnace 20 described later), so it has a structure that can concentrate the applied energy and thus induce a high melting rate.

[0053] In addition, the second melting furnace 20 in the dual type melting furnace F may be dedicated to serving as the second iron source ( Figure 4 The invention relates to a melting furnace for waste introduced into the electric furnace (shown as "2"), wherein it has substantially the same basic structure as any common electric furnace ("ordinary electric furnace"), and can be a main body in which a waste preheating furnace is additionally provided to achieve high rate / high efficiency operation.

[0054] Therefore, the first melting furnace 10 and the second melting furnace 20 used to constitute the dual-type melting furnace F are arranged into a dual-furnace structure, in which the two furnaces are at least partially combined to form a single body of a common lower unit 300, and in addition, efficient auxiliary equipment for applying chemical energy and controlling reactions in the furnace can be further arranged and operated (additional or auxiliary raw material and gas injectors, etc.; since the type and position of the equipment are freely operated as needed according to the concept of process design, the present invention will omit a detailed description thereof).

[0055] Hereinafter, the following description will be given to more specifically explain the first upper unit 100, the second upper unit 200, the lower unit 300, and the partition unit 400 constituting the first melting furnace 10 and the second melting furnace 20 in the above-described dual type melting furnace F.

[0056] like Figure 1 As shown, the first melting furnace 100 is made of a refractory material and can form a first upper space (A1-1) of the first melting furnace 10, in which the first iron source 1 is introduced and melted.

[0057] More specifically, the purpose of the first melting furnace 10 is to continuously introduce / melt the OBM as the first iron source 1 and the partially contained low-granularity scrap, and is characterized in that the arc generation position can be maintained at a predetermined position above the molten metal level (hot residual material ~ metal wire), so that the distance between the furnace wall of the first upper unit 100 and the ignition point can be maintained at a predetermined level. Therefore, unlike the common scrap melting furnace, high cooling performance in a specific working area may not be required. On the contrary, excessive cooling of the furnace wall will cause energy loss, which is inconsistent with the concept of the high energy concentrated furnace body of the first melting furnace 10 of the present invention. In addition, considering that the furnace wall scratch phenomenon that may occur in the scrap batch charging method will not occur in a dedicated furnace for continuously introducing / melting OBM and low-granularity scrap, it may be effective to form the furnace wall in the first upper unit 100 in view of the furnace body insulation concept.

[0058] However, in order to prevent the outer iron shell for fixing the refractory material (which has the function of limiting (or maintaining) the high heat in the furnace body) from deforming, a minimum water cooling device ( Figure 1 The outer shell water cooling structure is not shown).

[0059] like Figure 1 As shown, the first upper unit 100 may include: a first electrode member 110, at least a portion of which is inserted into the first upper space (A1-1) of the first melting furnace 10 through a small ceiling of a first furnace roof part 100a formed at the top of the first upper unit 100 and melts the first iron source 1 using arc heat; and a plurality of iron source feeders 120, which are radially arranged around the center of the first electrode member 110 and supply the first iron source 1 through the first upper space (A1-1) of the first melting furnace 10.

[0060] More specifically, if Figure 1 and Figure 2As shown, the first electrode member 110 may include a plurality of alternating current (AC) electrodes (111, 112, 113) radially arranged around the center of the small ceiling of the first furnace top part 100a, and a plurality of iron source feeders 120 may be provided in the same number as the plurality of AC electrodes (111, 112, 113) and respectively continuously supply the first iron source 1 toward the ignition points of the respective AC electrodes corresponding to the respective iron source feeders.

[0061] For example, the first electrode member 110 composed of a plurality of AC electrodes (111, 112, 113) (a direct current (DC) current system may also be introduced if necessary) is characterized in that the OBM (which has a relatively lower specific gravity than the molten steel) introduced into the first melting furnace 10 as the first iron source 1 may exist in the slag 4a or on the interface between the molten metal 3 and the slag 4a, and therefore, it may be effective to form a wider ignition point. In addition, at the start of operation, in order to protect the arc and prevent the arc from picking up nitrogen, it is necessary to foam the slag 4a. Thereafter, when a large amount of gangue is input by introducing the OBM and thus the amount of the slag 4a increases rapidly, the foaming of the slag 5a should be suppressed instead. Therefore, it may become important to monitor the level of the slag 4a in the first melting furnace 10. In addition, for the above-mentioned measurement of the slag level, the AC current system may be more advantageous.

[0062] In addition, the plurality of iron source feeders 120 are means for continuously introducing OBM as the first iron source 1 (if necessary, low-grained scraps may also be introduced). Although not shown, this may be a device for conveying the first iron source 1 from any storage facility of the corresponding main raw material to a conveyor belt, allowing the iron source to freely fall into the tubular baffle (converted from potential energy to kinetic energy) through a conveying hopper installed at a required height on the top of the first melting furnace 10, thereby ensuring sufficient kinetic energy, and then continuously introducing the first iron source 1 into the furnace through a plurality of input ports respectively arranged to correspond to the plurality of AC electrodes (111, 112, 113). More specifically, the plurality of iron source feeders 120 may continuously introduce the first iron source 1 into three ignition points formed between the plurality of AC electrodes (111, 112, 113) of the first electrode member 110, thereby maximizing the melting efficiency.

[0063] like Figure 1 As shown, the second upper unit 200 may be arranged in parallel with the first upper unit 100 in the horizontal direction (X-axis direction) and may form a second upper space (A2-1) of the second melting furnace 20, in which waste materials as the second iron source 2 are introduced and melted. In this case, the second iron source 2 may mainly include waste materials, in addition to some high-grained ore-based materials (OBM).

[0064] More specifically, based on the metal melting characteristics, the structure of the second melting furnace 20 can be similar to that of an ordinary electric furnace for melting general waste. Considering the mixed characteristics of the main raw materials used in the present invention, the input ratio of general waste is small and the height of the waste introduced / stacked in the furnace is low, so the up / down change of the position of the ignition point is relatively small (i.e., the spatial proximity between the furnace wall and the ignition point) compared with a typical electric furnace. However, the possibility of an increase in the local thermal effect of the furnace wall cannot be ruled out. In addition, as the input ratio decreases, it will be more effective to reduce energy loss by reducing the second upper space (A2-1) in the furnace, so the above-mentioned influence should also be considered. Therefore, the second upper unit 200 of the second melting furnace 20 is basically designed to be similar to a water cooling device in an ordinary electric furnace, and in addition, it can be configured as a water cooling device with a double-layer structure, the size of which is reduced and a thick slag coating for heat insulation can be effectively formed on the furnace wall, so that the second upper unit preferably becomes a system capable of controlling the cooling performance of each layer separately.

[0065] like Figure 1 As shown, the second upper unit 200 may include: a second electrode member 210, at least a portion of which is inserted into the second upper space (A2-1) of the second melting furnace 20 through a small ceiling of a second furnace top portion 200a formed at the top of the second upper unit 200 and melts the second iron source 2 using arc heat; and a preheating feeder 220, which is installed on one side of the second electrode member 210 at the top of the second upper unit 200, temporarily stores a predetermined amount of the second iron source 2 in a storage space inside the preheating feeder, and uses waste heat generated inside the second melting furnace 20 to preheat the second iron source 2 temporarily stored in the storage space, and then supplies the second iron source 2 through the second upper space (A2-1) of the second melting furnace 20.

[0066] For example, Figure 1As shown, the second electrode member 210 may include: an upper direct current (DC) electrode 211, which is inserted through the small ceiling of the second furnace top part 200a and is arranged on the second upper space (A2-1) side of the second melting furnace 20; a lower DC electrode 212, which is installed at the bottom of the lower unit 300, faces the upper DC electrode 211 in the vertical direction, and is arranged on the second lower space (A2-2) side of the second melting furnace 20. In this regard, the lower DC electrode 212 may include a first lower electrode 212a and a second lower electrode 212b, wherein the central axis of the first lower electrode is formed at the bottom of the lower unit 300 to be coaxial with the central axis of the upper DC electrode 211 so that the lower DC electrode can directly face the upper DC electrode 211, and the central axis of the second lower electrode is formed at the bottom of the lower unit 300 to be inclined at a predetermined angle relative to the central axis of the upper DC electrode 211, thereby being biased toward the preheating feeder 220 relative to the upper DC electrode 211, so that the lower DC electrode can face the upper DC electrode 211 in the inclined direction.

[0067] At this time, the second electrode member 210 may induce current between the upper DC electrode 211 and the second lower electrode 212b immediately after the preheating feeder 220 supplies the second iron source 2, and induce current between the upper DC electrode 211 and the first lower electrode 212a after the second iron source 2 is completely melted.

[0068] More specifically, as described above, the second electrode member 210 may be a DC electrode member, which is further provided with a second lower electrode 212b that is tilted toward the preheating feeder 220 relative to the upper DC electrode 211. As a dedicated furnace for melting general scrap, the second melting furnace 20 is basically free from restrictions in terms of the type of power supply system (AC or DC applicable), however, due to the placement of the preheating feeder 220, a structural restriction may be imposed, that is, when the second iron source 2 is loaded, the second iron source 2 may be introduced and excessively tilted toward the lower side of the preheating feeder 220, away from the center of the second electrode member 210.

[0069] In order to effectively melt the above-mentioned second iron source, it is necessary to concentrate the applied electric energy to the corresponding part. For this reason, it may be more advantageous to apply the DC current system to the second electrode member 210. For example, the advantage of the DC current system is that the current flow is formed between the upper DC electrode 211 and the lower DC electrode 212, that is, in the vertical direction. Therefore, when the second lower electrode 212b in the lower DC electrode 212 is placed to be deflected toward the lower side of the preheating feeder 220, the energy application can be deflected toward the corresponding part. In addition, after the melting of the introduced second iron source 2 is completed, it is important to apply uniform energy in the entire lower unit 300 of the second melting furnace 20. Therefore, like the existing ordinary DC furnace, the first lower electrode 212a is arranged directly below the upper DC electrode 211.

[0070] Therefore, during the process, by selectively using the two lower electrodes (212a, 212b) or changing their relative ratio, the flow of electric energy applied to the second melting furnace 20 can be controlled, which in turn can cause effective melting work. Although not shown, in connection with the above configuration, a device for introducing chemical energy as supplementary energy can also be provided at the furnace wall on the lower side of the preheating feeder 220.

[0071] In addition, the preheating feeder 220 may include: a preheating chamber 221, which is formed in a cylindrical shape or a polygonal column shape to extend in the vertical direction, thereby configuring a finger-type column furnace; and a chamber door 222, which is installed on the lower side of the opened preheating chamber 221 to selectively open the lower side of the preheating chamber 221 and thereby selectively supply the second iron source 2.

[0072] More specifically, in order to perform high-speed melting and reduce energy application, the preheating feeder 220 can be a device that preheats the second iron source 2 using the waste heat generated by the first melting furnace 10 and the second melting furnace 20 in the form of a finger-type column furnace, which is relatively advantageous in terms of maintenance and operation, and can be applied to the top of the second melting furnace 20.

[0073] The electric furnace 1000 provided with the dual type melting furnace F according to the present invention is appropriately designed for producing high-grade steel that must use a large amount of OBM, so the input ratio of the second iron source 2 (i.e., scrap) can be greatly reduced compared to a general electric furnace. Therefore, the preheating feeder 220 is preferably designed with a volume sufficient to receive all the second iron sources 2 required for the melting work at one time.

[0074] In addition, in order to make the preheating feeder 220 effectively utilize the waste heat generated in the first melting furnace 10, as shown in FIG. Figure 1As shown, the first upper unit 100 and the second upper unit 200 can be connected in the form of a pipeline to connect 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 together, so that the exhaust gas duct 500 can be installed to supply the waste heat generated in the first melting furnace 100 toward the second melting furnace 20.

[0075] More specifically, the preheating feeder 220 adopted by the second melting furnace 20 of the present invention is a preheating furnace that utilizes waste heat supplied in the form of waste gas discharged into the atmosphere without being used to produce molten metal among the energy applied to the furnace and can preheat the second iron source 2. However, when the partition unit 400 described later mechanically separates 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, a problem may arise that the waste heat generated by the first melting furnace 10 using half or more of the main energy application cannot be supplied.

[0076] In order to overcome the above problems, an exhaust gas duct 500 may be installed to connect 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, thereby ensuring the flow path of the exhaust heat generated in the first melting furnace 100. At the same time, it may be configured that an inlet for supplying exhaust gas from the first melting furnace 10 on one side of the second melting furnace 20 is located in the opposite direction of the preheating feeder 220, and the corresponding fluid flow passes through the arc generation position of the second melting furnace 20 and is then supplied to the preheating feeder 220, thereby also performing a sealing function of isolating the arc generated in the second electrode member 210 from the atmosphere.

[0077] Therefore, the exhaust gas duct 500 connecting 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 can perform two functions of recovering the waste heat generated in the first melting furnace 10 and simultaneously preventing the pickup phenomenon of nitrogen (N2) in the atmosphere entering the molten metal 3 through the arc flow.

[0078] like Figure 1 As shown, the lower unit 300 can be combined with the first upper unit 100 and the second upper unit 200 in the horizontal direction (X-axis direction) and the vertical direction (Z-axis direction), respectively, so that 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 can become a single integrated space.

[0079] In addition, the lower unit 300 can be provided with a discharge port 310 at a position corresponding to the first electrode member 110 (which is installed on the small ceiling of the first furnace top part 100a formed on the top of the first upper unit 100) on the floor surface forming the first lower space (A1-2) to discharge the molten metal 3 in the dual-type melting furnace F, wherein the floor surface forming the first lower space (A1-2) in the lower unit (where the discharge port 310 is formed) can be higher than the floor surface forming the second lower space (A2-2).

[0080] For example, in the case of the dual-type melting furnace F of the present invention, the upper units (100, 200) of the first melting furnace 10 and the second melting furnace 20 may be configured as two independent units, while the lower unit 300 may be a structure integrated in the form of a single furnace body. Therefore, the lower unit 300 has a structure in which the molten metal 3 is mixed, there is no underwater mountain structure for separating the first melting furnace 10 and the second melting furnace 20 from each other, and a profile in which the height of the bottom of the first melting furnace 10 is higher than that of the bottom of the second melting furnace 20 may be formed for the discharge of the molten metal and the maintenance of the discharge port 310. In addition, the lower unit may be configured to be installed on the lower side of the first melting furnace 10 without any protruding portion for installing the discharge port 310.

[0081] Such a structure of the lower unit 300 can allow substances and heat to move or flow freely, which in turn enables a separate resource (electricity, chemical energy) combination to be applied to the first melting furnace 10 and the second melting furnace 20. At the same time, it can realize a quick process design that simultaneously utilizes the functions of different kinds of slag (4a, 4b) separated in the first melting furnace 10 and the second melting furnace 20 respectively by the partition unit 400 described later.

[0082] In addition, as described in the structure of the above-mentioned lower unit 300, the discharge port 310 present in the lower unit 300 is designed with a structure having no undesirable cold zone by removing a protruding structure for discharge that is generally present in a general electric furnace. Therefore, when determining the position of the discharge port 310, in order to supply sand provided for sealing after discharge, such as Figure 3 As shown, the discharge port can be placed at a position directly below the inlet of any one of the plurality of AC electrodes (111, 112, 113) provided in the first electrode member 110, so that the discharge port can be configured to move the pipe supplying sand downward through the inlet of the AC electrode to fill the lower unit with sand.

[0083] Furthermore, if Figure 1 and Figure 3As shown, in order to control the flow of the molten metal 3 between the first melting furnace 10 and the second melting furnace 20, a bottom blowing device can be arranged at the bottom of the lower unit 300, and the bottom blowing device is provided with a plurality of plugs (600a, 600b, 600c, 600d, 600e, 600f, 600g) for discharging (or exhausting) gas.

[0084] For example, the first melting furnace 10 and the second melting furnace 20 are separated by the partition unit 400 in the integrated lower unit 300. In order to effectively realize a shortened process of simultaneously performing the desired melting and refining characteristics respectively suitable for the different purposes of the above furnaces, the flow (material flow and heat flow) of the molten metal should be appropriately adjusted according to the purpose of the detailed process. The formation of a deflected flow (a phenomenon in which the main flow is concentrated in one direction; first melting furnace 10->second melting furnace 20 or second melting furnace 20->first melting furnace 10), the formation of a flow that quickly and uniformly mixes the entire volume of the molten metal 3, etc. can be exemplified.

[0085] To this end, at the bottom of the lower unit 300 configuring the first melting furnace 10 and the second melting furnace 20, a bottom blowing device 600 may be installed to achieve the desired flow control. Figure 3 An example of a bottom blowing device 600 is shown, which is provided with plugs (600a, 600b, 600c, 600d, 600e, 600f, 600g) arranged at the bottom of the lower unit 300. However, the details of the device (type, size, number and position of the plugs) are not particularly limited to Figure 3 At this time, the type of gas introduced by the bottom blowing device 600 may include an inert gas (Ar, N2) for simple flow control or a fuel / raw material (O2, CH4, CO, etc.) for reaction and heat source supply that can be selectively introduced.

[0086] Furthermore, if Figure 1 As shown, a tilting device 700 can be provided on the lower side of the lower unit 300, which can tilt the dual-type melting furnace F that at least partially combines the first melting furnace 10 and the second melting furnace 20 in a horizontal direction (X-axis direction), or can tilt it in both directions in a horizontal direction perpendicular to the vertical direction (Z-axis direction) and in a width direction (Y-axis direction).

[0087] More specifically, the tilting device 700 may include: a supporting cylinder 710, which supports the dual-type melting furnace F and can tilt it to maintain the center of the dual-type melting furnace F tilted by the tilting device; and a plurality of (particularly, at least three) driving cylinders 720, which are radially arranged around the supporting cylinder 710 to support the dual-type melting furnace at at least three points, and can be driven upward and downward individually to selectively tilt the dual-type melting furnace in the horizontal direction (X-axis direction) or the width direction (Y-axis direction), wherein these components are installed on the lower side of the dual-type melting furnace F at a portion corresponding to the center of the dual-type melting furnace F.

[0088] For example, the supporting cylinder 710 of the tilting device 700 is a structure installed at the center of gravity of the dual-type melting furnace F, which may include: a tilting member that can tilt and support the dual-type melting furnace F in the horizontal direction (X-axis direction) and the width direction (Y-axis direction); and a cylinder member that is connected to the above-mentioned tilting member to insert the structure into the supporting surface of the dual-type melting furnace F, so that the cylinder can only move up and down without an alternative driving force, thereby playing a role in maintaining or fixing the position of the dual-type melting furnace F. Therefore, the supporting cylinder 710 is a device required to meet the necessity of distinguishing the discharge direction and the slag discharge direction to realize the structural characteristics of the dual-type melting furnace F of the present invention.

[0089] In addition, the plurality of driving cylinders 720 of the tilting device 700 is a control device for actually tilting the twin type melting furnace F, and each driving cylinder has a basic structure substantially similar to the supporting cylinder 710, but may be a hydraulic cylinder for applying a driving force, and may be fixed to the supporting surface of the twin type melting furnace F. Such a plurality of driving cylinders 720 may perform the tilting of the twin type melting furnace F by three-point support. However, in order to tilt the twin type melting furnace F stably, these may be composed of a total of four (4) cylinders, two of which are located on the first melting furnace 10 side and the other two on the second melting furnace 30 side relative to the supporting cylinder 710 holding the center of the twin type melting furnace F, thereby preferably tilting in two directions (horizontal direction (X-axis direction) and width direction (Y-axis direction)) of the twin type melting furnace F.

[0090] like Figure 1 As shown, the partition unit 400 can be installed between the first upper unit 100 and the second upper unit 200 of the double-type melting furnace F to rise and fall in the vertical direction (Z-axis direction), wherein it can selectively separate (or 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 originally integrated by the lower unit 300.

[0091] For example, the scrap fed as the second iron source 2 and melted in the second melting furnace 20 must form an oxidizing atmospheric slag 4b when melted. According to the operation of removing P as one of the impurities in the molten steel under an oxidizing atmosphere, the oxygen ions in the slag 4b can be combined with the P in the molten steel to generate P2O5. The generated P2O5 can become a component contained in the slag 4b to reduce the P content in the molten steel. In contrast, the OBM fed as the first iron source 1 and melted in the first melting furnace 10 must form a reducing atmospheric slag 4a when melted. After removing the oxygen in the FeO remaining in the OBM, the reduced Fe can be mixed into the molten steel, thereby playing a role in increasing the actual yield of the introduced OBM.

[0092] If OBM and scrap are used at the same time, the actual production of Fe may increase, but if the formed slag is reducing, P will be brought into the molten steel, thereby increasing the P content. On the other hand, if the formed slag is oxidizing, it is beneficial to remove P, but the actual production of Fe will decrease. In order to solve these problems, the first melting furnace 10 (an electric furnace used only for OBM) and the second melting furnace 20 (an electric furnace dedicated to scrap) can be combined to form a dual-type melting furnace F, in which the OBM-based slag 4a and the scrap-based slag 4b should be produced without mixing together. Therefore, it may be necessary to adopt a partition unit 400 in the dual-type melting furnace F that can distinguish the slags (4a, 4b) from each other.

[0093] Therefore, the basic objectives of the dual type melting furnace F according to the present invention are: to perform melting and partial refining work on main materials (OBM and general scrap) with different characteristics as the first iron source 1 and the second iron source 2, respectively, wherein these works can be performed simultaneously by separating the slag 4a of the first melting furnace 10 and the slag 4b of the second melting furnace 20; and to realize a process of producing high rate / high efficiency / high quality molten metal 3 by excluding a large amount of slag that has lost its original function or is not suitable for the final stage from the different kinds of slags (4a, 4b) produced in the above furnaces (10, 20) before the first melting furnace 10 and the second melting furnace 20 are integrated for final refining and endpoint control. If the combination of the corresponding main materials is applied to any conventional and typical electric furnace, it is basically impossible to achieve the above objectives.

[0094] For this purpose, as a means for controlling the separation / integration of the slag (4a, 4b) generated in the detailed process steps, a partition unit 400 may be provided. Herein, the partition unit 400 may be composed of a water-cooled structure and a refractory material, and may be adjusted by a driving device that moves up and down between the first melting furnace 10 and the second melting furnace 20. The above-mentioned device may be an important device for realizing the dual-type melting furnace F of the present invention in essence.

[0095] Specifically, in order to selectively discharge the slag 4a generated in the first melting furnace 10, the first melting furnace 10 of the double type melting furnace F (whose separation / integration can be selectively adjusted by the partition unit 400) may include a first slag door 11, which is formed in a plurality around the first melting furnace 10 substantially at a boundary portion between the first upper unit 100 and the lower unit 300, and is configured in the form of a double door, including an upper door 11a opened upward and a lower door 11b opened downward facing each other in a vertical direction (Z-axis direction). On the other hand, in order to selectively discharge the slag 4b generated in the second melting furnace 20, the second melting furnace 20 may include a second slag door 21, which is formed at a boundary portion between the second upper unit 200 and the lower unit 300 and is configured in the form of a single door opened upward or downward.

[0096] More specifically, the first slag door 11 formed by a double door (11a, 11b) in the first melting furnace 10 is a device for adjusting the level of the slag 4a produced in large quantities due to melting the OBM introduced as the first iron source 1, and can have a structure that can be opened upward / downward by the double door (11a, 11b).

[0097] The slag 4a produced in the first melting furnace 10 and the slag 4b produced in the second melting furnace 20 (the result of general waste work) mostly have different (composition) compositions. In addition, this difference can be partially controlled and maintained if necessary. Since the gangue components input from the OBM include acidic main components (SiO2, Al2O3), a low-basicity slag is formed and contains a large amount of FeO. The input FeO must be minimized and recovered by introducing C-based auxiliary raw materials. In addition, due to the CO gas generated in the above process, the slag 4a may foam. Since the slag 4a is produced in large quantities, if foaming occurs, the working stability may decrease, so it is preferable to maintain a low-basicity condition. However, on the other hand, there is a contradictory problem that without such foaming, the arc cannot be stabilized.

[0098] Therefore, in order to suppress foaming in the first melting furnace 10 while protecting the arc, it is necessary to keep a predetermined amount of slag 4a confined in the furnace, which can also be beneficial to the reduction reaction of FeO. Therefore, during operation, the (water-cooled) upper door 11a that opens upward is opened to maintain a predetermined level of slag 4a. Thereafter, if it is necessary to remove the slag 4a, the lower door 11b that opens downward is opened to control the above operation. At this time, in order to smoothly control a large amount of slag 4a, such as Figure 2 As shown, the first slag door 11 may be configured in a multi-door form, in which a plurality of doors are disposed around the first melting furnace 10 .

[0099] In addition, the second slag door 21 of the second melting furnace 20 is a device having the same function as an existing ordinary electric furnace, and can be used to discharge the slag 4b of the furnace. According to the present invention, the first slag door 11 installed in the first melting furnace 10 is characterized in that after taking appropriate measures, a large amount of slag 4a produced will be continuously discharged to maintain a desired level, and the second slag door 21 should be kept closed except for a specific purpose, and the first slag door has a structural form that can be driven in two directions (Y-axis direction, Z-axis direction), rather than a simple upward opening structure in the form of a water-cooled plate, which can be closed again after opening during operation.

[0100] Next, the following description will be given to describe the main features of the molten metal production operation performed by each detailed equipment and device of the dual type melting furnace F configuring the electric furnace 1000 according to the present invention.

[0101] like Figure 4 As shown, at the start of the operation, the partition unit 400 is maximally lowered, so that the first melting furnace 10 and the second melting furnace 20 are separated from each other, wherein the first melting furnace 10 can melt the OBM as the first iron source 1 continuously introduced through the plurality of iron source feeders 120, and the second melting furnace 20 can preheat the scrap as the second iron source 2 in the preheating feeder 220 by an electric arc, while the slag 4b is maintained in a foaming state, and melting energy can be further applied to the first melting furnace 10.

[0102] Afterwards, if Figure 5 As shown, the level of the molten metal 3 is increased (level -> level 2) through the melting process in the first melting furnace 10. If the increased level (level 2) reaches a level completely immersed in the molten metal 3 when the second iron source 2 being preheated is introduced, the chamber door 222 is opened to fill the molten metal 3 with the preheated second iron source 2 in the preheating chamber 221.

[0103] Therefore, the preheated second iron source 2 is filled according to the level of the molten metal 3, thereby achieving the effect of preventing nitrogen (N) from being picked up by the arc while ensuring the melting efficiency of the second iron source 2 (ie, scrap).

[0104] At this time, as the baffle unit 400 rises relative to the level of the molten metal 3, the flow channel of the molten metal 3 between the lower spaces (A1-2, A2-2) of the first melting furnace 10 and the second melting furnace 20 can be extended (material activation and heat exchange). In addition, the first electrode member 110 of the first melting furnace 10 and the second electrode member 210 of the second melting furnace 20 can also be appropriately raised relative to the level of the molten metal 3.

[0105] Then, if Figure 6As shown, in the first melting furnace 10, the upper door 11a of the first slag door 11 for adjusting the level of the slag 4a can be opened upward. On the other hand, in order to melt the second iron source 2 filled into the molten metal 3 and perform the next step, the new temporarily stored second iron source 2 in the preheating feeder 220 can be preheated in the second melting furnace 20. In this case, the partition unit 400 can be further raised in relation to the level of the molten metal 3, so that the flow channel of the molten metal 3 between the lower spaces (A1-2, A2-2) of the first melting furnace 10 and the second melting furnace 20 can be further extended (material activation and heat exchange). In addition, the first electrode member 110 of the first melting furnace 10 and the second electrode member 210 of the second melting furnace 20 can also be continuously raised in relation to the level of the molten metal 3.

[0106] Afterwards, if Figure 7 As shown, the baffle unit 400 is fully raised and fully opened, and after the slag 4a of the first melting furnace 10 (causing a decrease in refining performance) is discharged by opening the upper door 11a in the first slag door 11 upward, final refining can be performed by mixing the molten metal with the slag 4b of the second melting furnace 20. Therefore, by fully opening the baffle unit 400 and fully expanding the refining reaction interface area, the refining efficiency can be maximized.

[0107] In such Figures 4 to 7 In all the processes shown in FIG. 1 , due to the material exchange and heat exchange in the lower unit 300 integrating the first melting furnace 10 and the second melting furnace 20, the refining reaction can be continuously performed in the second melting furnace 20, and finally Figure 7 As shown, the maximum refining performance can be ensured after the diaphragm unit 400 is fully opened. At this time, the first melting furnace 10 can reduce a large amount of FeO input from the OBM by maintaining the reducing slag 4a until the diaphragm unit 400 is fully opened.

[0108] Furthermore, if Figure 8 As shown, when the molten metal 3 is discharged from the double-type melting furnace F, the driving cylinder 720 of the tilting device 700 on the side of the second melting furnace 20 is moved upward, which can cause the double-type melting furnace F to tilt in the horizontal direction (X-axis direction) so that the double-type melting furnace F can tilt in the direction of the first melting furnace 10 where the discharge port 310 is formed.

[0109] Furthermore, if Fig. 9As shown, in a state where the partition unit 400 separates (or separates) the first melting furnace 10 and the second melting furnace 20 during operation, if it is required to forcibly discharge the slag 4a in the first melting furnace 10 or the slag 4b in the second melting furnace 20, the dual-type melting furnace F can be tilted along the width direction (Y-axis direction) of the first melting furnace 700 by moving the driving cylinder 720 upwardly along the width direction (Y-axis direction) so that the dual-type melting furnace F can be tilted in the direction of the first slag door 11 in the first melting furnace 10 and the second slag door 21 in the second melting furnace 20.

[0110] In order to make the double type melting furnace F tilt smoothly (such as Figure 8 or Fig. 9 As shown in FIG. 1 , the preheating feeder 200 can be configured to be separated from the dual-type melting furnace F. According to the specific tilting device 700 proposed in the present invention, a driving program can be implemented to move the main body of the dual-type melting furnace F downward and tilt it in a desired direction.

[0111] Therefore, regarding the electric furnace 1000 according to an embodiment of the present invention, it is based on the simultaneous introduction of ore-based materials (OBM) and low-particle size waste and general waste, wherein the gangue components input in large quantities from the OBM can be effectively separated to prevent them from mixing with the existing slag (the gangue containing SiO2 and Al2O3 as main components mainly acts as acidic slag, and if the input amount is large, it may become a cause of introducing a large amount of CaO to refine / remove the P component in the molten steel. Therefore, the increase in the slag-making agent source unit and the large amount of slag produced thereby may become the main factors of uneconomic structures such as reduced molten steel recovery rate, increased energy consumption, and extended working time), thereby realizing a dual-type melting furnace capable of simultaneously melting the main raw materials and refining.

[0112] Therefore, in order to transform the traditional "blast furnace-converter" production system into an "electric furnace" production system, the present invention relates to a new concept of a melting method using an electric furnace, which introduces a large amount of ore-based iron source (represented by DRI) while ensuring the same or higher productivity / economic advantages / quality as the traditional "blast furnace-converter" production system, wherein a new electric furnace capable of using a large amount of OBM is adopted, thereby achieving the effect of carbon neutrality in the steelmaking industry.

[0113] For example, when applying the electric furnace with a dual type melting furnace configuration according to the present invention, by effectively separating and discharging gangue from the first melting furnace, the influence of gangue input in large quantities from DRI on the working and optimal refining conditions can be maintained / managed; it is possible to efficiently apply DRI in large quantities using the first melting furnace (for OBM only), thereby reducing the inclusion of components; according to the process of introducing / operating scrap through the first melting furnace (continuously filling the first melting furnace with OBM) and the second melting furnace connected to the first melting furnace in the form of a dual structure, perfect flat bath operation can be performed; due to the exhaust gas duct structure, nitrogen pickup can be effectively blocked by arc sealing, thereby ensuring the N output level of the converter. In addition, the high energy concentration structure of the first melting furnace, the preheating of scrap in the second melting furnace using exhaust gas, and the simultaneous operation of the first melting furnace and the second melting furnace can reduce energy consumption to a general scrap working level or lower, and shorten the operating time to the converter level.

[0114] For example, Fig.10 and Fig.11 As shown, regarding the effect of the embodiment of the present invention, when the DR grade DRI in Table 1 is applied in large quantities based on the actual operation results of the ordinary electric furnace, the expected operation indicators of the ordinary electric furnace and the present invention are compared with each other and shown in Table 2. At this time, the expected operation results are reflected by simple energy and material calculations, in which the main indicators are relative to the operation. Fig.10 The DRI components listed in the .

[0115] like Fig.11 As shown in Table 2 shown in , the power consumption of a conventional electric furnace is 617 kWh / ton. However, according to the expected operating indicators of the present invention, it is expected that 361 kWh / ton of electricity is used, indicating that the power consumption is reduced by about half compared with the conventional electric furnace. In addition, the operating time of the conventional electric furnace is about 84 minutes, while according to the expected operating results of the present invention, it takes about 39 minutes, thus indicating that the operating time is also reduced by about half compared with the conventional electric furnace. At this time, the Cu level and the N level are 0.03% and 30ppm, respectively, which are substantially similar to the levels of the converter and may be adjusted. Therefore, it is expected that the expected operating indicators of the present invention are substantially the same as or better than those of all scrap electric furnaces.

[0116] in this regard, Fig.11 The operating results of the conventional electric furnace are the average waste 100% actual operation implemented in the standard operation conventional electric furnace, while the expected operating indicators according to the embodiment of the present invention correspond to the application of DRI 80% + waste 30%.

[0117] Although the present invention has been described with reference to the embodiments shown in the accompanying drawings, this is only for illustrative purposes, and those skilled in the art will appreciate that various modifications and other equivalent embodiments can be obtained from the above embodiments. Therefore, the true and technical scope of the present invention to be protected will be defined by the technical spirit of the present invention in the appended claims described herein.

Claims

1. An electric furnace provided with a dual-type melting furnace, wherein the dual-type melting furnace includes two melting furnaces and the two melting furnaces are at least partially combined together to melt different iron sources, the electric furnace comprising: a first upper unit forming a first upper space of a first melting furnace into which a first iron source is introduced and melted; a second upper unit which is arranged in a horizontal direction of the first upper unit and forms a second upper space of a second melting furnace into which a second iron source is introduced and melted; a lower unit which is combined to lower portions of the first upper unit and the second upper unit and forms a single integrated space integrating a first lower space of the first melting furnace and a second lower space of the second melting furnace; as well as The partition unit, which is installed to vertically move up and down between the first upper unit and the second upper unit, serves to partition a first lower space of the first melting furnace and a second lower space of the second melting furnace, although the two lower spaces are integrally formed by the lower unit.

2. The electric furnace according to claim 1, wherein: The first upper unit has a furnace wall formed of a refractory material, so that the melting furnace has a refractory structure.

3. The electric furnace according to claim 1, wherein: The first upper unit comprises: a first electrode member, at least a portion of which is inserted into a first upper space of the first melting furnace through a small ceiling of a first furnace roof portion formed at the top of the first upper unit and melts the first iron source with arc heat; and A plurality of iron source feeders are radially arranged around the center of the first electrode member and supply a first iron source through a first upper space of the first melting furnace.

4. The electric furnace according to claim 3, wherein: The first electrode member includes a plurality of alternating current (AC) electrodes radially arranged around the center of the small ceiling of the first furnace roof part, The plurality of iron source feeders respectively continuously supply the first iron source toward the ignition points of the respective AC electrodes corresponding to the respective iron source feeders.

5. The electric furnace according to claim 1, wherein: The second upper unit comprises: a second electrode member, at least a portion of which is inserted into the second upper space of the second melting furnace through a small ceiling of a second furnace roof portion formed at the top of the second upper unit and melts the second iron source with arc heat; and A preheating feeder is installed on one side of the second electrode member at the top of the second upper unit, and a predetermined amount of the second iron source is temporarily stored in the storage space inside the preheating feeder, and the second iron source temporarily stored in the above storage space is preheated by using the waste heat generated in the second melting furnace, and then the second iron source is supplied through the second upper space of the second melting furnace.

6. The electric furnace according to claim 5, wherein: The second electrode member comprises: an upper direct current (DC) electrode inserted through a small ceiling of the second furnace roof portion and disposed on a second upper space side of the second melting furnace; and a lower DC electrode installed at the bottom of the lower unit to face the upper DC electrode in the vertical direction and disposed at the second lower space side of the second melting furnace, and Wherein, the lower DC electrode comprises: a first lower electrode whose central axis is formed at the bottom of the lower unit to be coaxial with the central axis of the upper DC electrode so that the lower DC electrode can directly face the upper DC electrode; and A second lower electrode, the central axis of which is formed at the bottom of the lower unit to be inclined at a predetermined angle relative to the central axis of the upper DC electrode, thereby being biased toward the preheating feeder relative to the upper DC electrode so that the lower DC electrode can face the upper DC electrode in an inclined direction.

7. The electric furnace according to claim 6, wherein: The second electrode member induces current between the upper DC electrode and the second lower electrode immediately after the second iron source is supplied from the preheating feeder, and induces current between the upper DC electrode and the first lower electrode after the second iron source is completely melted.

8. The electric furnace according to claim 1, wherein: The volume of the first melting furnace consisting of the first upper space of the first upper unit and the first lower space of the lower unit is smaller than the volume of the second melting furnace consisting of the second upper space of the second upper unit and the second lower space of the lower unit.

9. The electric furnace according to claim 1, wherein: In order to communicate the first upper space of the first melting furnace and the second upper space of the second melting furnace, the electric furnace further includes an exhaust gas duct connecting the first upper unit and the second upper unit in the form of a duct and supplying waste heat generated in the first melting furnace to the second melting furnace.

10. The electric furnace according to claim 1, wherein: The first melting furnace includes: a first slag door, which is arranged at a boundary portion between the first upper unit and the lower unit and is configured in a double door form, including an upwardly opened upper door and a downwardly opened lower door facing each other in a vertical direction, so that the slag generated in the first melting furnace can be selectively discharged.

11. The electric furnace according to claim 10, wherein: The first melting furnace opens an upper door during operation to maintain the height of slag in the first melting furnace at a predetermined level, and opens a lower door when discharging the slag in the first melting furnace.

12. The electric furnace according to claim 1, wherein: The second melting furnace includes a second slag door provided at a boundary portion between the second upper unit and the lower unit and configured in a single door form opened upward or downward so as to selectively discharge slag generated in the second melting furnace.

13. The electric furnace according to claim 1, wherein: In order to control the flow of the molten metal between the first melting furnace and the second melting furnace, the electric furnace further includes a bottom blowing device which is arranged at the bottom of the lower unit and provided with a plurality of plugs for discharging gas.

14. The electric furnace according to claim 1, wherein: The lower unit is provided with a discharge port at a position corresponding to the first electrode member on the floor surface forming the first lower space, so as to discharge the molten metal in the dual-type melting furnace, and the first electrode member is installed on the small ceiling of the first furnace roof part formed on the top of the first upper unit.

15. The electric furnace according to claim 14, wherein: In the lower unit, a floor surface forming the first lower space and having the discharge port formed therein is higher than a floor surface forming the second lower space.

16. The electric furnace according to claim 14, wherein: The electric furnace further includes a tilting device capable of tilting the dual-type melting furnace at least partially combining the first melting furnace and the second melting furnace in a horizontal direction, or tilting the dual-type melting furnace in a horizontal direction and a width direction perpendicular to the vertical direction.

17. The electric furnace according to claim 16, wherein: The tilting device comprises: a supporting cylinder for maintaining the center of the double-type melting furnace tilted by the tilting device and supporting the double-type melting furnace while enabling the double-type melting furnace to be tilted; and A plurality of drive cylinders, specifically, at least three drive cylinders, are radially arranged around the support cylinder to support the dual-type melting furnace at at least three points, and can be driven upward and downward individually to selectively tilt the dual-type melting furnace in a horizontal direction or a width direction.

18. The electric furnace according to claim 16, wherein: The tilting device tilts the double-type melting furnace in a horizontal direction, so that when the molten metal is discharged from the double-type melting furnace, the double-type melting furnace can be tilted in the direction of the first melting furnace formed with the discharge port; On the other hand, when discharging the slag inside the first melting furnace or the slag inside the second melting furnace, the tilting device tilts the dual-type melting furnace in the width direction so that the dual-type melting furnace can be tilted in the direction of the first slag door in the first melting furnace and in the direction of the second slag door in the second melting furnace.

19. The electric furnace according to claim 5, wherein: The preheating feeder comprises: a preheating chamber formed in a cylindrical shape or a polygonal column shape to extend in a vertical direction, thereby forming a finger-type column furnace; and A chamber door is installed at a lower side of the opened preheating chamber so as to selectively open the lower side of the preheating chamber.

20. The electric furnace according to claim 1, wherein: The first iron source introduced into the first melting furnace comprises an ore based material (OBM), The second iron source introduced into the second melting furnace comprises scrap.

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