Furnace bottom building method and structure of direct current submerged arc furnace and direct current submerged arc furnace

Abstract

The invention relates to the technical field of submerged arc furnaces, in particular to a direct current submerged arc furnace bottom building method and structure and a direct current submerged arc furnace. The method comprises the steps that multiple carbon block layers are sequentially and upwards built from the furnace bottom of the direct current submerged arc furnace in the axial direction of a furnace body of the direct current submerged arc furnace; wherein after the bottommost carbon block layer of the furnace bottom is built, a plurality of graphite electrodes of the direct-current submerged arc furnace are placed on the upper surface of the bottommost carbon block layer, and one end of each graphite electrode is concentrated in the center of the furnace bottom; partial electrodes at the other ends of the graphite electrodes are not located in the direct current submerged arc furnace, and a preset included angle is formed between every two adjacent graphite electrodes; a plurality of carbon block layers are sequentially built in an area defined by the inner side wall of a furnace body of the direct-current submerged arc furnace and the outer side wall of a graphite electrode, and the height of the upper surface of the graphite electrode is larger than that of the uppermost carbon block layer. When the furnace bottom of the direct current submerged arc furnace is built in the mode, the reliability, safety and stability of the furnace bottom are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of submerged arc furnaces, and particularly to a bottom masonry method, structure and direct current submerged arc furnace of a direct current submerged arc furnace. Background Art

[0002] A direct current submerged arc furnace is an industrial device that uses a direct current arc as a heat source for smelting and heating processes, and is widely used in fields such as metallurgy and chemical industry. Compared with traditional alternating current submerged arc furnaces, direct current submerged arc furnaces have higher energy efficiency and more stable operation. The bottom electrode of a direct current submerged arc furnace usually uses a graphite electrode. When the graphite electrode is used as the bottom electrode of the direct current submerged arc furnace, it needs to extend outside the submerged arc furnace to lead the current out of the direct current submerged arc furnace.

[0003] In some scenarios, in the masonry process of a direct current submerged arc furnace, the traditional method mostly uses a horizontal and vertical masonry method. This method can effectively stagger the masonry joints, which is not only beautiful but also performs well in terms of structural stability, and can ensure the normal use of the furnace bottom to a certain extent. However, for a direct current submerged arc furnace, the bottom electrodes of the direct current submerged arc furnace usually need to be led out in multiple directions, usually two or more. When the number of bottom electrodes is more than three, the original orderly carbon block placement pattern is broken. The originally neat and orderly carbon block layout becomes chaotic, and a large number of connections and overlaps appear in the masonry joints. The connection and overlap of the brick joints between the carbon blocks greatly increase the risk of molten iron penetrating the furnace bottom. Once the molten iron penetrates the furnace bottom, it will seriously damage the bottom structure of the direct current submerged arc furnace, resulting in production interruption and safety hazards. In addition, the large swing of the molten iron at the furnace bottom will scour the bottom electrode, thereby shortening the service life of the bottom electrode. Therefore, when the furnace bottom of a direct current submerged arc furnace is masonry by the above method, its reliability, safety and stability are all relatively low. Summary of the Invention

[0004] In order to solve the technical problems that the masonry structure of the furnace bottom of a direct current submerged arc furnace has relatively low reliability, safety and stability, the purpose of the present invention is to provide a bottom masonry method, structure and direct current submerged arc furnace of a direct current submerged arc furnace. The specific technical solutions adopted are as follows: In a first aspect, an embodiment of the present invention discloses a method for laying the furnace bottom of a DC submerged arc furnace, which includes: starting from the furnace bottom of the DC submerged arc furnace and successively laying multiple layers of carbon blocks upward along the axial direction of the furnace body of the DC submerged arc furnace. The laying methods of adjacent carbon block layers are different. The gaps between the carbon blocks of adjacent carbon block layers are staggered with each other, and the gaps between the carbon blocks of the same carbon block layer are also staggered with each other; wherein, after the carbon block layer at the bottommost layer of the furnace bottom is laid, a plurality of graphite electrodes of the DC submerged arc furnace are placed on the upper surface of the bottommost layer of the carbon block layer. One end of each graphite electrode is concentrated and placed at the center of the furnace bottom, and a part of the other end of each graphite electrode is not inside the DC submerged arc furnace, and the adjacent graphite electrodes form a predetermined angle; in the area surrounded by the inner side wall of the furnace body of the DC submerged arc furnace and the outer side wall of the graphite electrode, multiple layers of carbon block layers are successively laid, and the height of the upper surface of the graphite electrode is higher than the height of the uppermost layer of the carbon block layer, so as to separate the molten liquid near the furnace bottom in the DC submerged arc furnace through the graphite electrode.

[0005] Optionally, the carbon block layer includes three layers. Starting from the furnace bottom of the DC submerged arc furnace and successively laying multiple layers of carbon block layers upward along the axial direction of the furnace body of the DC submerged arc furnace includes: the bottommost layer of the carbon block layer and the uppermost layer of the carbon block layer are laid in a first laying method, and the middle layer of the carbon block layer is laid in a second laying method; the first laying method is a parallel arrangement method, and the parallel arrangement method is to use one of the graphite electrodes as a reference electrode, and the long sides of the carbon blocks are arranged and laid successively in a way perpendicular to the reference electrode. The second laying method is a radial method, and the radial method is to arrange and lay the long sides of the carbon blocks pointing to the central axis of the DC submerged arc furnace successively.

[0006] Optionally, each graphite electrode includes a graphite electrode body and a low thermal conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low thermal conductivity carbon block, and a part of the other end of the graphite electrode body is not inside the DC submerged arc furnace. Placing the multiple graphite electrodes of the DC submerged arc furnace on the upper surface of the bottommost layer of the carbon block layer, and concentrating one end of each graphite electrode at the center of the furnace bottom includes: placing each graphite electrode of the DC submerged arc furnace on the upper surface of the bottommost layer of the carbon block layer, and the other ends of the low thermal conductivity carbon blocks are spliced with each other to form a radial layout. The low thermal conductivity carbon block is used to prevent the heat at the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

[0007] Optionally, the graphite electrode body and the low thermal conductivity carbon block are bonded and fixed with a ceramic binder, and the area where the other ends of the low thermal conductivity carbon blocks are spliced and contacted with each other is bonded and fixed with a ceramic binder.

[0008] Optionally, the gaps between the carbon blocks of each layer of the carbon block layer are filled with a carbonaceous binder, and the parts of the inner side wall of the furnace body of the DC submerged arc furnace in contact with the carbon blocks and the parts of the outer side wall of the graphite electrode in contact with the carbon blocks are both filled with a carbonaceous binder.

[0009] Second aspect, an embodiment of the present invention discloses a bottom lining structure of a DC submerged arc furnace, including: multiple layers of carbon block layers sequentially and upwardly built by carbon blocks along the axial direction of the furnace body of the DC submerged arc furnace. The laying methods of adjacent carbon block layers are different. The gaps between carbon blocks in adjacent carbon block layers are mutually staggered, and the gaps between carbon blocks in the same carbon block layer are also mutually staggered; the bottommost carbon block layer is laid flat on the furnace bottom of the DC submerged arc furnace, and multiple graphite electrodes of the DC submerged arc furnace are placed on the upper surface of the bottommost carbon block layer. One end of each graphite electrode is concentrated and placed at the center of the furnace bottom, and part of the other end of each graphite electrode is not inside the DC submerged arc furnace, and a predetermined angle is formed between adjacent graphite electrodes; the remaining carbon block layers are sequentially and upwardly built along the axial direction of the DC submerged arc furnace and are located in the area surrounded by the inner side wall of the furnace body of the DC submerged arc furnace and the outer side wall of the graphite electrode. The height of the upper surface of the graphite electrode is higher than the height of the uppermost carbon block layer, so as to separate the molten liquid near the furnace bottom in the DC submerged arc furnace by the graphite electrode.

[0010] Optionally, each graphite electrode includes a graphite electrode body and a low thermal conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low thermal conductivity carbon block. Part of the other end of the graphite electrode body is not inside the DC submerged arc furnace. Each graphite electrode of the DC submerged arc furnace is placed on the upper surface of the bottommost carbon block layer. The other ends of each low thermal conductivity carbon block are spliced together in a radial layout. The low thermal conductivity carbon block is used to prevent the heat at the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

[0011] Optionally, the carbon block layer includes three layers. The bottommost carbon block layer and the uppermost carbon block layer are laid in a first laying method, and the middle carbon block layer is laid in a second laying method; The first laying method is a parallel arrangement method. The parallel arrangement method is to use one of the graphite electrodes as a reference electrode, and the long sides of the carbon blocks are sequentially laid perpendicular to the reference electrode. The second laying method is a radial method. The radial method is to sequentially lay the long sides of the carbon blocks pointing to the central axis of the DC submerged arc furnace.

[0012] Third aspect, an embodiment of the present invention discloses a DC submerged arc furnace, including: multiple graphite electrodes and the bottom lining structure of the DC submerged arc furnace mentioned in the second aspect. The multiple graphite electrodes of the DC submerged arc furnace are placed on the upper surface of the bottommost carbon block layer of the bottom lining structure. One end of each graphite electrode is concentrated and placed at the center of the furnace bottom. Part of the other end of each graphite electrode is not inside the DC submerged arc furnace, and a predetermined angle is formed between adjacent graphite electrodes; the remaining carbon block layers of the bottom lining structure are sequentially and upwardly built along the axial direction of the DC submerged arc furnace and are located in the area surrounded by the inner side wall of the furnace body of the DC submerged arc furnace and the outer side wall of the graphite electrode. The height of the upper surface of the graphite electrode is higher than the height of the uppermost carbon block layer, so as to separate the molten liquid near the furnace bottom in the DC submerged arc furnace by the graphite electrode.

[0013] Optionally, each graphite electrode includes a graphite electrode body and a low-thermal-conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low-thermal-conductivity carbon block, and a part of the electrode at the other end of the graphite electrode body is not located inside the DC submerged arc furnace. Each graphite electrode of the DC submerged arc furnace is placed on the upper surface of the bottommost carbon block layer. The other ends of the low-thermal-conductivity carbon blocks are spliced together radially. The low-thermal-conductivity carbon blocks are used to prevent the heat at the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

[0014] An embodiment of the present invention discloses a method for laying the furnace bottom of a DC submerged arc furnace. By successively laying multiple carbon block layers upward along the axial direction of the furnace body of the DC submerged arc furnace starting from the furnace bottom of the DC submerged arc furnace, the laying methods of adjacent carbon block layers are different, the gaps between the carbon blocks of adjacent carbon block layers are mutually offset, and the gaps between the carbon blocks of the same carbon block layer are mutually offset; wherein, after the bottommost carbon block layer at the furnace bottom is laid, multiple graphite electrodes of the DC submerged arc furnace are placed on the upper surface of the bottommost carbon block layer. One end of each graphite electrode is concentrated at the center of the furnace bottom, a part of the electrode at the other end of each graphite electrode is not located inside the DC submerged arc furnace, and a predetermined included angle is formed between adjacent graphite electrodes; multiple carbon block layers are successively laid in the area enclosed by the inner sidewall of the furnace body of the DC submerged arc furnace and the outer sidewall of the graphite electrode, and the height of the upper surface of the graphite electrode is higher than the height of the uppermost carbon block layer.

[0015] Thus, in the embodiments of the present invention, by adopting the scheme of different masonry methods for adjacent carbon block layers with misaligned gaps, the drawback that stress concentration paths are easily formed due to aligned gaps in the traditional single masonry method is solved. Moreover, the misalignment of the gaps between carbon blocks and the layout where the gaps between carbon blocks in adjacent carbon block layers are also misaligned greatly increases the path length and difficulty of the penetration of media such as gas and liquid. During the smelting process, it can effectively prevent high-temperature flue gas, molten metal, etc. from leaking through the gaps at the furnace bottom, reduce the risk of erosion of insulating materials, and maintain good insulation performance of the furnace body. At the same time, good sealing helps to keep the smelting atmosphere in the furnace stable, avoid the entry of impurities such as air from affecting the smelting reaction, and provide guarantee for the production of high-quality products. The layout method of concentrating one end of multiple graphite electrodes at the center of the furnace bottom, with the other end partially extending out of the furnace body and maintaining a predetermined angle, makes the electrodes more evenly stressed during the smelting process, avoids the phenomena of arc deviation and arc breakage of the electrodes due to uneven stress in the traditional layout, ensures stable current conduction, and improves the electric energy conversion efficiency. At the same time, using the graphite electrodes to divide the space at the furnace bottom into multiple regions reduces the swinging amplitude of the molten iron at the furnace bottom, thereby reducing the scouring degree of the bottom electrodes by the molten iron, and further prolonging the service life of the bottom electrodes. Therefore, when the furnace bottom of a DC submerged arc furnace is masonry in the above manner in the embodiments of the present invention, the reliability, safety, and stability of the furnace bottom are improved. In addition, the carbon block layers in this area further reinforce the furnace body structure, provide a stable support environment for the graphite electrodes, and enhance the stability of the graphite electrodes in the furnace and the stability of the entire furnace body system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic flow chart of a method for masonry the furnace bottom of a DC submerged arc furnace disclosed in the embodiments of the present invention.

[0017] Figure 2 It is a schematic diagram of a masonry structure of the furnace bottom of a DC submerged arc furnace disclosed in the embodiments of the present invention.

[0018] Figure 3 It is a schematic diagram of a carbon block layer masonry in the first masonry method for the bottommost carbon block layer and the topmost carbon block layer disclosed in the embodiments of the present invention.

[0019] Figure 4 It is a schematic diagram of a carbon block layer masonry in the second masonry method for the middle carbon block layer disclosed in the embodiments of the present invention.

[0020] Figure 5 It is a schematic diagram of the structure of a graphite electrode and the structure between the graphite electrode and the carbon block layer disclosed in the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following combines the accompanying drawings and preferred embodiments to specifically describe a method for laying the furnace bottom, structure, and direct current submerged arc furnace according to the present invention, including its specific implementation manner, structure, features, and effects, as follows. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0023] The following specifically describes the specific solutions of a method for laying the furnace bottom, structure, and direct current submerged arc furnace provided by the present invention with reference to the accompanying drawings.

[0024] Please refer to Figure 1 , Figure 1 which is a schematic flow chart of a method for laying the furnace bottom of a direct current submerged arc furnace disclosed in an embodiment of the present invention. The method includes the following steps: Step S101: Starting from the furnace bottom of the direct current submerged arc furnace, lay multiple layers of carbon block layers upward in sequence along the axial direction of the furnace body of the direct current submerged arc furnace. The laying methods of adjacent carbon block layers are different, the gaps between the carbon blocks in adjacent carbon block layers are offset from each other, and the gaps between the carbon blocks in the same carbon block layer are offset from each other.

[0025] Among them, after the bottommost layer of carbon block layer at the furnace bottom is laid, place multiple graphite electrodes of the direct current submerged arc furnace on the upper surface of the bottommost layer of carbon block layer. One end of each graphite electrode is concentrated at the center of the furnace bottom, and part of the other end of each graphite electrode is not inside the direct current submerged arc furnace, and the adjacent graphite electrodes form a predetermined angle.

[0026] Lay multiple layers of carbon block layers in sequence in the area surrounded by the inner side wall of the furnace body of the direct current submerged arc furnace and the outer side wall of the graphite electrode, and the height of the upper surface of the graphite electrode is higher than the height of the uppermost layer of carbon block layer, so as to separate the molten liquid near the furnace bottom in the direct current submerged arc furnace through the graphite electrode.

[0027] Specifically, in the embodiment of the present invention, starting from the furnace bottom of the DC submerged arc furnace, multiple layers of carbon blocks are successively laid from bottom to top along the axial direction of the furnace body. To enhance the structural strength and sealing performance of the furnace body, different laying methods are adopted for adjacent carbon block layers. Specifically, one of the adjacent carbon block layers can adopt the method of laying with staggered joints horizontally, arranging the carbon blocks horizontally, and staggering the long-side joints of adjacent carbon blocks. The other carbon block layer can adopt the butting method, arranging the carbon blocks longitudinally, forming a crisscross structure between adjacent carbon block layers. In this way, the gaps between the carbon blocks in adjacent carbon block layers are misaligned with each other, effectively avoiding the stress concentration phenomenon and the problem of molten iron penetrating downward due to the penetration of the gaps, and enhancing the furnace body's ability to resist high temperature, high pressure, and chemical erosion. In addition, one of the adjacent carbon block layers can also adopt a parallel arrangement method, and the other carbon block layer can also adopt a radial arrangement method.

[0028] Furthermore, within the same carbon block layer, the gaps between each carbon block also follow the misalignment principle. During the laying process, the position of the carbon blocks and the width of the gaps are precisely controlled, and the misalignment width between the gaps is determined according to the size of the carbon blocks. This enables media such as gas and liquid to pass through the gaps along a longer and more tortuous path when permeating, preventing molten iron from directly penetrating downward to the bottom of the furnace bottom through the penetrated gaps, effectively preventing leakage of high-temperature flue gas, molten metal, etc. from the gaps, and protecting the internal structure of the furnace bottom.

[0029] Furthermore, after completing the laying of the carbon block layer at the bottommost layer of the furnace bottom, the installation of graphite electrodes is carried out. A plurality of graphite electrodes are neatly placed on the upper surface of the bottommost carbon block layer. One end of each graphite electrode converges at the center of the furnace bottom to form a convergence point, and the other end partially extends outside the DC submerged arc furnace, forming an outwardly divergent layout. A specific predetermined angle (for example, 30° - 60°, and the specific angle can be determined according to the furnace body diameter of the DC submerged arc furnace and the number of graphite electrodes) is maintained between adjacent graphite electrodes. This layout method makes the current distribution more uniform when the graphite electrodes are energized, effectively avoiding problems such as partial arc and arc breakage, ensuring the stability of the arc, and improving the electric energy conversion efficiency.

[0030] Furthermore, in the annular region enclosed by the inner sidewall of the furnace body of the DC submerged arc furnace and the outer sidewall of the graphite electrodes, multiple layers of carbon block layers are successively laid upward. During the laying process, the height of the carbon block layer is strictly controlled to ensure that the height where the upper surface of the graphite electrode is located is always higher than the height where the topmost carbon block layer is located. This enables the graphite electrode to better contact the materials in the furnace during the smelting process, and at the same time avoids the shielding of the graphite electrode by the carbon block layer, ensuring that the arc can fully act on the materials. In addition, the carbon block layer in this region further strengthens the furnace body structure, provides a stable support environment for the graphite electrode, and enhances the stability of the graphite electrode in the furnace and the stability of the entire furnace body system. Further, as an optional embodiment of the present invention, the carbon block layer includes three layers. Starting from the furnace bottom of the DC submerged arc furnace and sequentially upward along the axial direction of the furnace body of the DC submerged arc furnace, multiple layers of carbon block layers are constructed, including: the bottommost carbon block layer and the uppermost carbon block layer are constructed in a first construction method, and the middle carbon block layer is constructed in a second construction method; the first construction method is a parallel arrangement method, and the parallel arrangement method is to use one of the graphite electrodes as a reference electrode, and the long sides of the carbon blocks are arranged and constructed in sequence perpendicular to the reference electrode. The second construction method is a radial method, and the radial method is to arrange and construct the long sides of the carbon blocks pointing to the central axis of the DC submerged arc furnace in sequence.

[0031] Exemplarily, as Figures 2 to 4 shown, Figure 2 is a schematic diagram of the furnace bottom masonry structure of a DC submerged arc furnace disclosed in an embodiment of the present invention, Figure 3 is a schematic diagram of a carbon block layer constructed by the bottommost carbon block layer and the uppermost carbon block layer in the first construction method in an embodiment of the present invention, Figure 4 is a schematic diagram of a carbon block layer constructed by the middle carbon block layer in the second construction method in an embodiment of the present invention. As can be seen from Figure 2 , the carbon block layer is inside the furnace body and the total height of the carbon block layer is lower than the height where the graphite electrodes are located. As can be seen from Figure 3 and Figure 4 , in the embodiment of the present invention, the gaps between the carbon block layers constructed by the uppermost and bottommost layers in the first construction method and the carbon block layers constructed by the middle layer in the second construction method are mutually offset, and the gaps between the carbon blocks in the same carbon block layer are also mutually offset. It should be noted that the construction method of the carbon block layer can also be other methods, and the embodiment of the present invention does not limit this here.

[0032] Further, as an optional embodiment of the present invention, each graphite electrode includes a graphite electrode body and a low thermal conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low thermal conductivity carbon block, and a part of the other end of the graphite electrode body is not inside the DC submerged arc furnace. Place the multiple graphite electrodes of the DC submerged arc furnace on the upper surface of the bottommost carbon block layer. The placement of one end of each graphite electrode concentrated at the center of the furnace bottom includes: placing each graphite electrode of the DC submerged arc furnace on the upper surface of the bottommost carbon block layer, and the other ends of the low thermal conductivity carbon blocks are spliced together in a radial layout. The low thermal conductivity carbon blocks are used to prevent the heat at the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

[0033] Exemplarily, as Figure 5 shown, Figure 5Schematic diagrams of the structure of a graphite electrode and the structure between the graphite electrode and the carbon block layer disclosed in the embodiments of the present invention. Among them, the graphite electrode body is made of a special graphite material with high purity and high density, having excellent electrical conductivity and high-temperature resistance characteristics. Its resistivity is low, enabling efficient conduction of current, ensuring that during the smelting process of a DC submerged arc furnace, the current can be stably and with low loss transmitted from the external power source to the furnace interior, generating continuous and stable arc heat. At the same time, graphite has good thermal shock resistance and can withstand frequent temperature changes during the smelting process, avoiding electrode cracking or breakage caused by thermal stress. The low thermal conductivity carbon block can select a new type of carbon material with extremely low thermal conductivity, and its thermal conductivity is only 1 / 10 - 1 / 20 of the graphite electrode body (the specific value depends on the material formula). This material has a special porous honeycomb-like microstructure inside, and a large number of closed pores effectively block the heat conduction path, effectively blocking the high temperature between the graphite electrode body and the center of the furnace.

[0034] Further, after the bottommost layer of the carbon block layer at the furnace bottom is laid, the installation of the graphite electrodes begins. Each graphite electrode uses the low thermal conductivity carbon block as a connection medium, and the other ends of them are spliced together in a radial layout. During the installation process, a high-precision laser locator can be used to strictly control the angles and positions of each graphite electrode, ensuring that the error of the predetermined included angle between adjacent graphite electrodes does not exceed ±0.5°, thereby ensuring the uniformity of the current distribution. In order to achieve the tight splicing of the low thermal conductivity carbon blocks, the splicing surface of each low thermal conductivity carbon block is machined with high precision to form a tenon and mortise structure with concave-convex fit. When splicing, a layer of ceramic binder, or high-temperature sealant, or carbonaceous binder is first applied to the surface of the tenon and mortise structure. This ceramic binder or high-temperature sealant or carbonaceous binder will solidify to form a tough sealing layer in a high-temperature environment, which not only enhances the connection strength at the splicing point but also further improves the heat insulation effect. After splicing, a hydraulic fastening device is used to uniformly press the entire radial graphite electrode group, so that the low thermal conductivity carbon blocks are seamlessly fitted together to form a stable overall structure.

[0035] Thus, during the operation of the DC submerged arc furnace, the low-thermal-conductivity carbon blocks effectively block the high temperature at the furnace center with their excellent heat insulation performance, keeping the temperature of the graphite electrode body within a reasonable range (usually reducing the temperature rise by 30% - 50%). The lower operating temperature significantly slows down the oxidation rate of the graphite electrode body and extends the service life of the electrode. According to actual operation data statistics, the electrode replacement cycle can be extended by 1.5 - 2 times. The radial layout allows the current to evenly disperse from the center of the furnace bottom to the surroundings, forming a symmetric and stable electric field distribution inside the furnace. This uniform current conduction not only improves the electric energy conversion efficiency, reducing the smelting energy consumption by 10% - 15%, but also ensures uniform heating of the materials inside the furnace, promotes full chemical reactions, and improves the product quality and output. At the same time, the stable electrode structure and current distribution reduce the occurrence frequency of electrode arc deviation, arc breakage and other faults, lower the equipment maintenance cost and downtime, and improve the continuous operation ability of the DC submerged arc furnace.

[0036] Furthermore, the graphite electrode body and the low-thermal-conductivity carbon blocks are bonded and fixed with a ceramic binder. The areas where the other ends of the low-thermal-conductivity carbon blocks are spliced and in contact with each other are also bonded and fixed with a ceramic binder. At the joint surface of the graphite electrode body and the low-thermal-conductivity carbon blocks, a gradient composite transition layer structure can be adopted to avoid interface cracking caused by differences in the thermal expansion coefficients of the materials and ensure the long-term stability of the connection strength and heat insulation performance.

[0037] Furthermore, the gaps between the carbon blocks in each layer of the carbon block layer are filled with a carbonaceous binder. The parts of the inner sidewall of the DC submerged arc furnace in contact with the carbon blocks and the outer sidewall of the graphite electrode in contact with the carbon blocks are both filled with a carbonaceous binder.

[0038] Specifically, the carbonaceous binder is made based on high-purity carbon materials, adding special high-temperature-resistant inorganic binders and modified additives. Its main components include graphite powder, carbon black, pitch coke, etc., and has a thermal expansion coefficient similar to that of the carbon blocks, which can expand and contract synchronously with the carbon blocks in a high-temperature environment, avoiding gap cracking caused by differences in thermal expansion and contraction. The high-temperature-resistant inorganic binders added to the inorganic binder, such as aluminum phosphate, silica sol, etc., will undergo chemical reactions at high temperatures to form a high-strength ceramic-like bonding phase, significantly improving the bonding strength. The modified additives can optimize the rheological properties of the binder, making it have good fluidity at room temperature for easy construction operation, and quickly hardening and forming during the heating and curing process. In addition, the carbonaceous binder has excellent chemical stability and can resist the erosion of high-temperature flue gas, molten metal, and corrosive gases generated during the smelting process of the DC submerged arc furnace. Its anti-seepage performance is outstanding, which can effectively prevent the leakage of gases and liquids inside the DC submerged arc furnace through the gaps, maintain the stability of the smelting atmosphere inside the furnace, and reduce the damage to the furnace body structure.

[0039] Furthermore, when filling the gaps between carbon blocks in each layer, during the carbon block masonry process, leave gaps with appropriate widths (usually controlled at 3 - 5 mm), and clean the surfaces of the carbon blocks on both sides of the gaps. Use tools such as wire brushes and compressed air to remove surface dust, oil stains, and loose particles to ensure the cleanliness and roughness of the bonding surface, thereby enhancing the adhesion of the binder. Then, inject the prepared carbonaceous binder into the gaps through a special extrusion type caulking gun. During the filling process, keep the caulking gun moving at a uniform speed to ensure that the binder evenly fills the entire gap, avoiding voids or bubbles. For wider gaps, a layered filling method can be adopted. After each layer is filled, wait for the binder to initially cure (about 1 - 2 hours), and then proceed with the next layer of filling to ensure the filling density. After filling is completed, use a scraper to trim the surface of the gap to make it flush with the surface of the carbon block, reducing stress concentration at the gap.

[0040] Furthermore, for the parts of the inner sidewall of the DC submerged arc furnace in contact with the carbon blocks and the outer sidewall of the graphite electrode in contact with the carbon blocks, before installing the carbon blocks, first evenly apply a layer of carbonaceous binder with a thickness of about 1 - 2 mm on the inner sidewall of the furnace and the outer sidewall of the electrode to form a continuous bonding layer. Then, accurately install the carbon blocks in place, and use a special pressing device to apply a certain pressure to the carbon blocks (the pressure value is set according to the carbon block size and binder characteristics, generally 0.5 - 1 MPa) to make the carbonaceous binder fully fill the tiny gaps between the carbon blocks and the wall surface and discharge the air. During the filling process, pay special attention to the corners and irregular parts, and manual smearing and compaction methods can be used for supplementary treatment to ensure that each contact point is fully bonded. For the contact part between the graphite electrode and the carbon block, since the graphite electrode will vibrate during operation, after filling the carbonaceous binder, a layer of high-temperature resistant fiber-reinforced material also needs to be wrapped outside the contact area to further enhance the connection stability and prevent the binder from cracking or falling off due to vibration.

[0041] Furthermore, in the embodiments of the present invention, through the filling treatment of the carbonaceous binder, in terms of sealing performance, the continuous sealing layer formed after the filling of the carbonaceous binder completely seals the gaps, reducing the leakage rate of furnace gas and liquid by more than 90%, effectively maintaining the high-temperature and high-pressure smelting environment in the furnace, and reducing heat loss and energy consumption. In terms of structural stability, the carbonaceous binder is tightly combined with the carbon blocks, the furnace body, and the graphite electrodes to form an integral structure, enhancing the furnace body's ability to resist thermal stress and mechanical stress. The high-strength bonding phase generated after the curing of the binder can effectively disperse the stress between the carbon blocks and between the carbon blocks and other components, avoiding the breakage or displacement of the carbon blocks caused by stress concentration, and extending the service life of the furnace body. In addition, good sealing and stable structure also help to reduce the emission of pollutants during the smelting process, improving the working environment. At the same time, it reduces the failure frequency of the equipment caused by poor sealing and unstable structure, reduces the maintenance workload and downtime, and improves the production efficiency of the DC submerged arc furnace.

[0042] Based on the same inventive concept, the embodiments of the present invention also provide a bottom lining structure of a DC submerged arc furnace, including multiple layers of carbon block layers sequentially built upward along the axial direction of the furnace body of the DC submerged arc furnace by carbon blocks. The laying methods of adjacent carbon block layers are different, the gaps between the carbon blocks of adjacent carbon block layers are mutually staggered, and the gaps between the carbon blocks of the same carbon block layer are mutually staggered; the bottommost carbon block layer is laid flat on the furnace bottom of the DC submerged arc furnace, and multiple graphite electrodes of the DC submerged arc furnace are placed on the upper surface of the bottommost carbon block layer. One end of each graphite electrode is concentrated at the center of the furnace bottom, and part of the other end of each graphite electrode is not inside the DC submerged arc furnace, and a predetermined angle is formed between adjacent graphite electrodes; the remaining carbon block layers are sequentially built upward along the axial direction of the DC submerged arc furnace and are located in the area surrounded by the inner sidewall of the furnace body of the DC submerged arc furnace and the outer sidewall of the graphite electrode. The height of the upper surface of the graphite electrode is higher than the height of the uppermost carbon block layer, so as to separate the molten liquid near the furnace bottom in the DC submerged arc furnace through the graphite electrodes.

[0043] Furthermore, as an optional embodiment of the present invention, each graphite electrode includes a graphite electrode body and a low-thermal-conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low-thermal-conductivity carbon block, and part of the other end of the graphite electrode body is not inside the DC submerged arc furnace. Each graphite electrode of the DC submerged arc furnace is placed on the upper surface of the bottommost carbon block layer, and the other ends of each low-thermal-conductivity carbon block are spliced together in a radial layout. The low-thermal-conductivity carbon block is used to prevent the heat at the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

[0044] Further, as an optional embodiment of the present invention, the carbon block layer includes three layers. The bottom carbon block layer and the top carbon block layer are laid in a first laying method, and the middle carbon block layer is laid in a second laying method; the first laying method is a parallel arrangement method. The parallel arrangement method is to use one of the graphite electrodes as a reference electrode, and the long sides of the carbon blocks are arranged and laid in turn perpendicular to the reference electrode. The second laying method is a radial method. The radial method is to arrange and lay the long sides of the carbon blocks pointing to the central axis of the DC submerged arc furnace in turn.

[0045] It should be noted that the bottom lining structure of the DC submerged arc furnace provided by the embodiment of the present invention and the bottom lining method of the DC submerged arc furnace provided by the embodiment of the present invention are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned bottom lining method of the DC submerged arc furnace, and has the same or similar beneficial effects, and the repeated parts will not be described again.

[0046] Based on the same inventive concept, the embodiment of the present invention provides a DC submerged arc furnace, which includes a plurality of graphite electrodes and the bottom lining structure of the DC submerged arc furnace mentioned in the above embodiment. The plurality of graphite electrodes of the DC submerged arc furnace are placed on the upper surface of the bottom carbon block layer of the bottom lining structure. One end of each graphite electrode is concentrated and placed at the center of the furnace bottom. Part of the other end of each graphite electrode is not inside the DC submerged arc furnace, and a predetermined angle is formed between adjacent graphite electrodes; the remaining carbon block layers of the bottom lining structure are sequentially laid upward along the axis of the DC submerged arc furnace and are located in the area surrounded by the inner side wall of the furnace body of the DC submerged arc furnace and the outer side wall of the graphite electrode. The height of the upper surface of the graphite electrode is higher than the height of the topmost carbon block layer, so as to separate the molten liquid near the furnace bottom in the DC submerged arc furnace through the graphite electrode.

[0047] Optionally, as an optional embodiment of the present invention, each graphite electrode includes a graphite electrode body and a low-thermal-conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low-thermal-conductivity carbon block. Part of the other end of the graphite electrode body is not inside the DC submerged arc furnace. Each graphite electrode of the DC submerged arc furnace is placed on the upper surface of the bottom carbon block layer. The other ends of each low-thermal-conductivity carbon block are spliced together in a radial layout, and the low-thermal-conductivity carbon block is used to prevent the heat at the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

[0048] It should be noted that the DC submerged arc furnace provided by the embodiment of the present invention and the bottom lining method of the DC submerged arc furnace provided by the embodiment of the present invention are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned bottom lining method of the DC submerged arc furnace, and has the same or similar beneficial effects, and the repeated parts will not be described again.

[0049] It should be noted that the above order of the embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0050] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments.

Claims

1. A method for building the bottom of a DC ore-fired furnace, characterized in that: include: Starting from the bottom of the DC ore-fired furnace, multiple layers of carbon blocks are sequentially laid upward along the axial direction of the furnace body of the DC ore-fired furnace, the laying methods of adjacent carbon block layers are different, the gaps between the carbon blocks of adjacent carbon block layers are staggered, and the gaps between the carbon blocks of the same carbon block layer are staggered; After the bottom carbon block layer of the furnace bottom is built, a plurality of graphite electrodes of the DC ore-fired furnace are placed on the upper surface of the bottom carbon block layer, one end of each graphite electrode is placed at the center of the furnace bottom, and a portion of the other end of each graphite electrode is not in the DC ore-fired furnace and adjacent graphite electrodes form a predetermined angle; Multiple layers of carbon blocks are sequentially built in the area enclosed by the inner wall of the furnace body of the DC electric arc furnace and the outer wall of the graphite electrode, and the height of the upper surface of the graphite electrode is higher than the height of the topmost carbon block layer, so that the molten liquid near the bottom of the DC electric arc furnace can be separated by the graphite electrode.

2. The method for building the furnace bottom of a DC ore-fired furnace according to claim 1, characterized in that: The carbon block layer comprises three layers, and the multiple carbon block layers are sequentially built upward along the axial direction of the furnace body of the DC ore-fired furnace from the furnace bottom of the DC ore-fired furnace, comprising: The bottom charcoal block layer and the top charcoal block layer are built in the first masonry method, and the middle charcoal block layer is built in the second masonry method; The first masonry method is a parallel arrangement method, in which one of the graphite electrodes is used as a reference electrode, and the long side of the carbon block is perpendicular to the reference electrode and arranged in sequence. The second masonry method is a radial method, in which the long side of the carbon block is directed to the central axis of the DC ore-fired furnace and arranged in sequence.

3. The method for building the furnace bottom of a DC ore-fired furnace according to claim 1, characterized in that: Each of the graphite electrodes comprises a graphite electrode body and a low thermal conductivity carbon block, one end of the graphite electrode body is fixedly connected to one end of the low thermal conductivity carbon block, and part of the electrode at the other end of the graphite electrode body is not in the DC ore-fired furnace, and the plurality of graphite electrodes of the DC ore-fired furnace are placed on the upper surface of the bottom carbon block layer, and one end of each graphite electrode is concentrated at the center of the furnace bottom and placed, comprising: The graphite electrodes of the DC electric arc furnace are placed on the upper surface of the bottom carbon block layer, and the other ends of the low thermal conductivity carbon blocks are spliced ​​together in a radial layout. The low thermal conductivity carbon blocks are used to prevent the heat in the center of the DC electric arc furnace from being transferred to the graphite electrode body.

4. The method for building the furnace bottom of a DC ore-fired furnace according to claim 3, characterized in that: The graphite electrode body and the low thermal conductivity carbon block are bonded and fixed by using a ceramic adhesive, and the other ends of the low thermal conductivity carbon blocks are bonded and fixed in the areas where they are spliced ​​and contacted with each other by using a ceramic adhesive.

5. The method for building the furnace bottom of a DC ore-fired furnace according to claim 1, characterized in that: The gaps between the carbon blocks in each carbon block layer are filled with a carbon binder, and the portion where the inner wall of the DC ore body contacts the carbon blocks and the portion where the outer wall of the graphite electrode contacts the carbon blocks are filled with the carbon binder.

6. A furnace bottom masonry structure of a DC ore-fired furnace, characterized in that: include: Multiple carbon block layers are formed by sequentially laying carbon blocks upward along the axial direction of the furnace body of the DC ore-fired furnace, wherein adjacent carbon block layers are laid in different ways, gaps between carbon blocks in adjacent carbon block layers are mutually staggered, and gaps between carbon blocks in the same carbon block layer are mutually staggered; The bottom carbon block layer is laid flat on the bottom of the DC ore-fired furnace, and a plurality of graphite electrodes of the DC ore-fired furnace are placed on the upper surface of the bottom carbon block layer, one end of each graphite electrode is placed at the center of the furnace bottom, and a portion of the other end of each graphite electrode is not in the DC ore-fired furnace, and adjacent graphite electrodes form a predetermined angle; The remaining carbon block layers are built upward in sequence along the axial direction of the DC electric arc furnace and are located in the area surrounded by the inner wall of the furnace body of the DC electric arc furnace and the outer wall of the graphite electrode. The height of the upper surface of the graphite electrode is higher than the height of the topmost carbon block layer, so that the molten liquid near the bottom of the DC electric arc furnace can be separated by the graphite electrode.

7. The furnace bottom masonry structure of the DC ore-fired furnace according to claim 6, characterized in that: Each of the graphite electrodes includes a graphite electrode body and a low thermal conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low thermal conductivity carbon block. Part of the electrode at the other end of the graphite electrode body is not in the DC submerged arc furnace. Each graphite electrode of the DC submerged arc furnace is placed on the upper surface of the bottom carbon block layer. The other ends of each of the low thermal conductivity carbon blocks are spliced ​​together in a radial layout. The low thermal conductivity carbon blocks are used to prevent the heat in the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

8. The furnace bottom masonry structure of the DC ore-fired furnace according to claim 6, characterized in that: The carbon block layer comprises three layers, the bottom carbon block layer and the top carbon block layer are built in a first masonry method, and the middle carbon block layer is built in a second masonry method; The first masonry method is a parallel arrangement method, in which one of the graphite electrodes is used as a reference electrode, and the long side of the carbon block is perpendicular to the reference electrode and arranged in sequence. The second masonry method is a radial method, in which the long side of the carbon block is directed to the central axis of the DC ore-fired furnace and arranged in sequence.

9. A DC ore-fired furnace, characterized in that: The invention comprises a plurality of graphite electrodes and a furnace bottom masonry structure of a DC ore-fired furnace as claimed in any one of claims 6 to 8, wherein the plurality of graphite electrodes of the DC ore-fired furnace are placed on the upper surface of the carbon block layer of the bottom layer of the furnace bottom masonry structure, one end of each graphite electrode is placed at the center of the furnace bottom, a part of the other end of each graphite electrode is not in the DC ore-fired furnace, and a predetermined angle is formed between adjacent graphite electrodes; The remaining carbon block layers of the furnace bottom masonry structure are built upward in sequence along the axial direction of the DC electric arc furnace and are located in the area surrounded by the inner wall of the furnace body of the DC electric arc furnace and the outer wall of the graphite electrode. The height of the upper surface of the graphite electrode is higher than the height of the topmost carbon block layer, so that the molten liquid near the furnace bottom in the DC electric arc furnace can be separated by the graphite electrode.

10. The DC ore-fired furnace according to claim 9, characterized in that: Each of the graphite electrodes includes a graphite electrode body and a low thermal conductivity carbon block. One end of the graphite electrode body is fixedly connected to one end of the low thermal conductivity carbon block. Part of the electrode at the other end of the graphite electrode body is not in the DC submerged arc furnace. Each graphite electrode of the DC submerged arc furnace is placed on the upper surface of the bottom carbon block layer. The other ends of each of the low thermal conductivity carbon blocks are spliced ​​together in a radial layout. The low thermal conductivity carbon blocks are used to prevent the heat in the center of the DC submerged arc furnace from being transferred to the graphite electrode body.

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