Slag grate for submerged arc furnace and preparation method of slag grate

Abstract

The invention belongs to the technical field of submerged arc furnaces, and discloses a slag grate device for a submerged arc furnace and a preparation method thereof.The outer portion of a slag grate pool is provided with a cuboid steel shell with an opening in the upper portion, a refractory brick layer is laid in the shell, a slag grate pool body formed through casting is arranged on the refractory brick layer, and a molten iron inlet channel is formed in the upper end of an inner cavity of the slag grate pool body; a molten iron outlet channel is arranged at the lower end of the inner cavity of the slag grate tank body; the slag grate is manufactured through the steps of shell welding, anchoring part welding, refractory brick layer laying, formwork erecting, castable preparing, pouring, baking and the like. The castable is prepared from fused mullite, tabular corundum, andalusite, alumina micro powder, silicon carbide, aluminate cement, metal silicon powder, metal aluminum powder, boron carbide, a carbon source, 316L stainless steel fibers and the like. According to the invention, a composite slag grate pool and slag baffle structure is adopted, castable components are optimized, molten iron and slag separation channels are reasonably arranged, molten iron and slag are thoroughly separated, slag is not adhered to the slag baffle, and the service life of the slag grate is prolonged.

Description

Technical Field

[0001] This invention relates to the field of submerged arc furnace technology, and in particular to a slag grate for a submerged arc furnace and its preparation method. Background Technology

[0002] An electric submerged arc furnace (EAF) is a high-power industrial furnace primarily used for the reduction and smelting of ores, carbonaceous reducing agents, and solvents. It mainly produces ferroalloys such as ferrosilicon, ferromanganese, ferrochrome, ferrotungsten, and ferrosilicon-manganese alloys. An EAF primarily consists of a furnace shell, furnace cover, furnace lining, short mesh, water cooling system, flue gas system, dust removal system, electrode pressing and lifting system, loading and unloading system, hydraulic system, casting system, and various electrical equipment. The slag grate in the EAF casting system is a device for separating molten slag from molten iron during the tapping process. Effectively separating molten iron from slag is crucial for ensuring casting quality and improving metal yield.

[0003] Traditional techniques typically involve excavating simple slag and iron pits on the ground and placing cast iron slag baffles inside to separate the slag and iron. However, when molten iron flows over these baffles, the slag and iron mix easily due to the baffles' rudimentary design and placement within the pit, lacking effective guidance. This makes separation difficult. Furthermore, the cast iron baffles, generally made of cast iron, have poor resistance to high-temperature oxidation, thermal shock, and slag corrosion. Their average lifespan is short, requiring replacement every 2-3 days. Additionally, high-temperature molten slag adheres to the baffles' surface, making cleaning labor-intensive and time-consuming. Each batch of molten iron produced from the grate pit requires partial cleaning or maintenance, increasing downtime, material consumption, and labor costs. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a slag grate for a submerged arc furnace and its preparation method, which adopts a composite slag pool and slag baffle structure to improve the overall service life of the slag grate and overcome the problems of frequent maintenance and short service life of existing slag grates.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a slag grate for an electric arc furnace, comprising a slag grate pool, the slag grate pool having an open rectangular steel shell at the top, the shell being welded together from a base and four side walls, both the base and side walls being covered with refractory brick layers, and the slag grate pool body, cast from castable refractory material, being placed on the refractory brick layers. The bottom of the inner cavity of the slag grate pool body is a rectangular recessed bottom, and molten iron is provided at the upper end of the inner cavity of the slag grate pool body along the length of the slag grate pool. The slag pool body has an inlet channel and an outlet channel for molten iron at the lower end of its internal cavity. The two sides of the internal cavity extend upward and outward from the recessed opening at the bottom of the pool, forming a smooth, sloping side. The left side of the internal cavity extends upward from the bottom of the pool to form a hump-shaped left edge, and the right side extends upward from the bottom of the pool to form a flat right edge. A slag baffle is placed horizontally inside the internal cavity of the slag pool body, and an arc-shaped lifting ring is fixed at the top center of the baffle.

[0006] The molten iron inlet channel is connected to the main iron trough. The bottom of the molten iron inlet channel is arc-shaped, smoothly transitioning upwards with a slope. The molten iron outlet channel is connected to the branch iron trough. The bottom of the molten iron outlet channel is flat, smoothly transitioning upwards on both sides with a slope. The cross-sections of both the molten iron inlet channel and the molten iron outlet channel are trapezoidal, with rounded transitions at the four corners.

[0007] The bottom height of the molten iron inlet channel is less than the bottom height of the molten iron outlet channel; on the same horizontal line, the width of the molten iron inlet channel is greater than the width of the molten iron outlet channel; the bottom height of the molten iron outlet channel is 200mm lower than the height of the slag discharge groove; the iron support trough connected to the molten iron outlet channel has a downward tilt angle of 13°; the separated molten iron is discharged into the molten iron pool through the iron support trough, and the molten iron channel is set at the bottom of the slag baffle plate B.

[0008] The left side edge of the slag grate pool body has a flange surface protruding in the middle and on both sides, and the two sides of the middle flange surface have recessed slag discharge grooves; the height of the flange surface is the same as the height of the right side edge; the height of the slag discharge groove is less than the bottom height of the molten iron outlet channel; at the same height level, the width of the slag discharge groove near the molten iron inlet channel is greater than the width of the slag discharge groove at the molten iron outlet channel; a slag discharge hole is provided at the bottom of the slag discharge groove and is connected to the slag ditch, through which the slag is discharged into the slag pool.

[0009] The outer shell sidewall of the grate pool is higher than the refractory brick layer, and the height of the cast grate pool body is flush with the height of the outer shell sidewall.

[0010] The slag baffle is divided into two types: slag baffle A and slag baffle B. Slag baffle A has a square cross-section and is a rectangular cross-section with a trapezoidal longitudinal section. The width of slag baffle A is the same as the width of slag baffle B. The slope of the trapezoid of slag baffle B is the same as the slope of the two sides of the inner cavity of the grate pool. There is a molten iron channel between the bottom of slag baffle B and the bottom of the inner cavity of the grate pool.

[0011] A method for preparing a slag grate for a submerged arc furnace includes the following steps: Step 1: Welding of the slag grate shell Based on the different sizes of the slag grate designed on site, the outer shell is welded first, and vent holes are evenly distributed on the side wall of the outer shell; the vent holes are 20mm round holes, and the distance between the outer edges of two adjacent vent holes is 200-250mm; Step 2: Anchor welding The anchors are evenly distributed and firmly welded to the inner wall of the steel outer shell of the slag pool, with a spacing of 200-250mm; the anchors are American-style anchors with an inverted "V" shape. Step 3: Laying the refractory brick layer A layer of refractory bricks is laid on the base and side walls of the outer shell; Step 4: Formwork The model is assembled and welded according to the shape of the inner cavity of the slag pool, and then the formwork is erected. Step 5: Preparation of Castable Refractories The raw materials used in the preparation of the castable and their weight proportions are as follows: 25-45 parts fused mullite, 20-45 parts tabular corundum, 2-10 parts andalusite, 3-8 parts alumina powder, 2-10 parts silicon carbide, 2-8 parts aluminate cement, 0.5-1.5 parts metallic silicon powder, 0.1-0.45 parts metallic aluminum powder, 0.1-0.5 parts boron carbide, 2-3 parts carbon source, 2-7 parts 316L stainless steel fiber; 0.2-0.6 parts water-reducing agent, and 3-8 parts water. Prepare the raw materials according to the above proportions, put them into a mixer and mix for 3-5 minutes, then add water-reducing agent and water and mix for 10-30 minutes to form Al2O3-SiC-C castable. Step Six: Pouring The prepared Al2O3-SiC-C castable was poured into the inner cavity mold of the grate pool and the mold of the slag baffle plate, respectively. After vibration molding and curing at room temperature for 24-48 hours, the material was demolded. An anti-sticking agent was sprayed or applied to the slag baffle plate. Step 7: Baking After demolding, bake at 150-220℃ for 70-74 hours before use.

[0012] Among them, the alumina content in the fused mullite is >75%, and the particle size of the fused mullite consists of three types: 5-8mm, 3-5mm, and 3-1mm, with a mass ratio of 1-4:1-3:3-5.

[0013] Among them, tabular corundum includes tabular corundum particles with a particle size of 0-1mm, and 200-mesh and 325-mesh tabular corundum fine powder, with a mass ratio of 2-4:2-3:1-3.

[0014] Among them, the SiC content in silicon carbide is ≥98%, and the particle size is 1-0 mm.

[0015] Among them, the boron carbide particle size is ≤0.075mm.

[0016] The andalusite contains two particle sizes: 3-1 mm and ≤0.074 mm, with a mass ratio of 2-4:1-2; and the AL2O3 content in the andalusite is ≥57%.

[0017] The carbon source is a composite carbon source of carbon black and spherical pitch, with a mass ratio of 1:1-1.5.

[0018] The water-reducing agent is at least one of sodium hexametaphosphate and sodium tripolyphosphate.

[0019] Molten iron and slag have different densities; the heavier molten iron settles at the bottom, while the lighter slag floats on the surface. Through the separation by the slag grate, the molten iron overflows from the holes below the baffle plate and flows out through the molten iron outlet channel into the support trough. The slag, blocked by the baffle plate, flows away through the slag discharge groove into the slag channel. The baffle plate consists of baffle plate A and baffle plate B. B is placed inside the cavity of the slag grate body, while baffle plate A and baffle plate B are placed adjacent to each other on the left edge of the cavity of the slag pool, on a flange surface with a central protrusion. During the use of the slag grate, the lower part of baffle plate B is continuously eroded by molten iron and slag. The height of baffle plate B supports its gradual descent, continuing to serve its function of blocking slag and effectively extending the overall service life of the baffle plate.

[0020] During use, slag grates are mainly subjected to the mechanical scouring of high-temperature molten iron, the chemical erosion of slag, and the thermal stress caused by intermittent tapping. At the same time, long-term use at high temperatures causes the inner lining material to shrink, crack, and peel off. Therefore, the refractory material for the inner cavity of the slag grate must have sufficient strength, good resistance to high-temperature molten slag erosion, and thermal shock stability against temperature changes.

[0021] Mullite has advantages such as high melting point, good erosion resistance, and good thermal shock stability. It can also adsorb FeO in molten slag, reducing its erosion of the slag grate.

[0022] Adding an appropriate amount of Al2O3 micro powder fills the internal pores of the castable, making it denser and enhancing the cohesive bonding effect, thus significantly improving the strength, increasing the bulk density, and reducing the apparent porosity of the castable.

[0023] Adding 316L stainless steel fibers increases the strength of the castable, ensuring that the grate pool and slag baffle will not crack or burst under rapid heating and cooling conditions.

[0024] Adding andalusite enhances the stability of castables at high temperatures. Andalusite irreversibly transforms into mullite and SiO2 phases at 1000-1400℃, accompanied by a 3-5% volume expansion. This ensures the castable has suitable dimensions and good high-temperature performance after firing. Andalusite also exhibits good resistance to high-temperature creep and thermal shock. The addition of andalusite utilizes high-temperature decomposition to produce capillary mullite, forming a needle-like, interlocking structure, thereby improving the high-temperature performance of the castable. Furthermore, the excess SiO2-rich glassy phase generated during this transformation process is mostly contained within the mullite crystals. The silicon-rich liquid phase produced by the mullite transformation of andalusite promotes sintering and fills pores. Andalusite itself has an anisotropic coefficient of thermal expansion; during the sintering cooling process, microcracks form between the andalusite aggregate and the matrix due to stress, effectively buffering the thermal stress generated by the volume change of mullite, thus giving the castable good thermal shock resistance.

[0025] The quality and particle size of the added andalusite significantly affect the initiation temperature and process of the mullitization reaction. Controlling the particle size of andalusite allows control over the degree of decomposition and transformation. As the particle size of the introduced andalusite decreases, the degree of mullitization gradually increases during heat treatment. The silica-rich liquid phase generated by the decomposition of andalusite at high temperatures promotes sintering, leading to a gradual increase in the room-temperature flexural strength and elastic modulus of the castable. High impurity content in andalusite promotes its decomposition, resulting in the extrusion of more SiO2 glass phase onto the surface. This blocks the pore channels of the castable, hindering oxygen from entering the sample and thus improving the castable's oxidation resistance. These glass phases react with alumina in the matrix to generate more secondary mullite, which fills the gaps between the aggregate and matrix, acting as a reinforcing agent and reducing the porosity of the castable, thereby further improving its high-temperature strength and oxidation resistance.

[0026] Introducing an appropriate amount of boron carbide into the castable results in a relatively dense sintered layer on the surface of the aggregate particles. This promotes a good sintering reaction between the aggregate and the matrix, leading to transgranular fracture and improved mechanical properties. Furthermore, it stimulates the formation and development of mullite whiskers in the matrix, increasing the number of whiskers and significantly increasing their aspect ratio, resulting in an interlocking structure. The pull-out effect of the mullite whiskers at high temperatures increases the high-temperature strength of the castable, effectively improving its mechanical properties. However, excessive addition leads to an increase in the liquid phase at high temperatures, which in turn inhibits the formation of mullite whiskers.

[0027] The composite carbon source of carbon black and spherical pitch offers better hydrophilicity and filling effect, resulting in castables with superior oxidation resistance and slag resistance. Under high-temperature thermal stress, the agglomerated structure of carbon black breaks down and penetrates into the pores and between particles of the material, forming a vein-like carbon network structure, which improves its high-temperature flexural strength. This not only alters the liquid phase distribution within the Al2O3-SiC-C castable at high temperatures but also reacts with Si or Al in the castable to generate non-oxides, resulting in finer pore sizes and enhanced internal bonding. Furthermore, the carbon content is less prone to slag wetting and has a high thermal conductivity, improving the castable's slag resistance and thermal shock resistance, thus extending the service life of the grate.

[0028] An anti-slag-sticking agent is sprayed or coated onto the slag-blocking plate, effectively preventing molten slag from adhering to it. This commercially available agent is a clay-like mixture primarily composed of aluminosilicates, with Al2O3 and SiO2 as its main chemical components. Before use, add 25-30 wt% water, stir thoroughly, and then spray or coat it onto the surface of the slag-blocking plate to a thickness of 3-5 mm. It exhibits excellent adhesion. The anti-slag-sticking agent isolates the slag-blocking plate from air contact. At high temperatures, the equilibrium phases of the coating are all high-melting-point phases, effectively isolating the slag-blocking plate from the molten slag, significantly improving slag adhesion, avoiding arduous manual slag cleaning, and extending the service life of the slag grate.

[0029] The beneficial effects of this invention are as follows: This invention adopts a composite slag pool and slag baffle structure, and rationally sets up the molten iron channel and molten slag separation channel, so that the molten iron and molten slag go through separate channels, achieving complete separation of molten iron and molten slag; the composition and dosage configuration of the castable material of the slag pool are optimized, the slag baffle does not stick to slag, and it does not need to be replaced after one month of use, saving downtime, material consumption and labor maintenance costs, and increasing the service life of the slag grate to more than 5 years. Attached Figure Description

[0030] Figure 1 This is a top view of the slag collection tank of the present invention. Figure 2 This is a schematic diagram of the AA section of the slag collection tank of the present invention; Figure 3 This is a schematic diagram of the cross-section of the BB section of the slag collection tank of the present invention; Figure 4 This is a schematic diagram of the CC section of the slag collection tank of the present invention; Figure 5 This is a top view schematic diagram of the combined structure of the slag grate, slag baffle, and iron discharge trough of the present invention. Figure 6 This is a side view of the combined structure of the slag grate, slag baffle, and iron discharge trough of the present invention. Figure 7 This is a schematic diagram of the structure of the slag baffle plate A and slag baffle plate B of the present invention.

[0031] Marked in the diagram: 1. Slag grate pool; 2. Molten iron inlet channel; 3. Molten iron outlet channel; 4. Left edge; 5. Right edge; 6. Slag discharge groove; 7. Slag grate pool body; 8. Outer shell; 9. Refractory brick layer; 10. Molten iron channel; 11. Slag baffle plate A; 12. Slag baffle plate B; 13. Iron support trough. Detailed Implementation

[0032] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments. Example 1

[0033] A slag grate for an electric arc furnace includes a slag pool 1. The slag pool 1 has an external rectangular steel shell 8 with an open top. The shell 8 is welded together from a base and four side walls. Refractory brick layers 9 are laid on both the base and side walls. A slag pool body 7, cast from refractory material, is placed on the refractory brick layers 9. The bottom of the inner cavity of the slag pool body 7 is a rectangular recessed bottom. An iron inlet channel 2 is provided at the upper end of the inner cavity of the slag pool body 7 along the length of the slag pool 1. The lower end of the inner cavity of the body 7 is provided with an iron outlet channel 3. The two sides of the inner cavity of the grate pool body 7 extend upward and outward from the recessed opening at the bottom of the pool to form a smooth side with an sloping angle. The left side of the inner cavity of the grate pool body 7 extends upward from the bottom of the pool to form a left edge 4 with a camel hump shape. The right side of the inner cavity of the grate pool body 7 extends upward from the bottom of the pool to form a right edge 5 with a flat surface. A slag baffle is placed horizontally inside the inner cavity of the grate pool body 7. An arc-shaped hanging ring is fixed at the top center of the slag baffle.

[0034] The molten iron inlet channel 2 is connected to the main iron trough. The bottom of the molten iron inlet channel 2 is arc-shaped, smoothly transitioning upwards with a slope. The molten iron outlet channel 3 is connected to the branch iron trough 13. The bottom of the molten iron outlet channel 3 is flat, with both sides of the bottom smoothly transitioning upwards with a slope. The cross-sections of both the molten iron inlet channel 2 and the molten iron outlet channel 3 are trapezoidal, with rounded transitions at the four corners.

[0035] The bottom height of the molten iron inlet channel 2 is less than the bottom height of the molten iron outlet channel 3; on the same horizontal line, the width of the molten iron inlet channel 2 is greater than the width of the molten iron outlet channel 3; the bottom height of the molten iron outlet channel 3 is 200mm lower than the height of the slag discharge groove; the iron support trough 13 connected to the molten iron outlet channel 3 has a downward tilt angle of 13°; the separated molten iron is discharged into the molten iron pool through the iron support trough 13, and the molten iron channel 10 is set at the bottom of the slag baffle plate B12.

[0036] The left side edge of the inner cavity of the slag pool body 7 has a flange surface protruding in the middle and on both sides, and the two sides of the middle flange surface have recessed slag discharge grooves 6; the height of the flange surface is the same as the height of the right side edge 5; the height of the slag discharge groove 6 is less than the bottom height of the molten iron outlet channel 3; at the same height level, the width of the slag discharge groove 6 near the molten iron inlet channel 2 is greater than the width of the slag discharge groove 6 at the molten iron outlet channel 3; the lower part of the slag discharge groove 6 is provided with a slag discharge hole connected to the slag ditch, and the slag is discharged into the slag pool through the slag ditch.

[0037] The outer shell 2 of the grate pool 1 has a side wall that is higher than the refractory brick layer 9. The height of the cast grate pool body 7 is flush with the height of the outer shell 8 of the grate pool 1.

[0038] The slag baffle is divided into two types: slag baffle A11 and slag baffle B12. Slag baffle A12 has a square cross-section and is a long strip with a rectangular cross-section and a trapezoidal longitudinal section. The width of slag baffle A11 is the same as the width of slag baffle B12. The slope of the trapezoid of slag baffle B12 is the same as the slope of the two sides of the inner cavity of the slag pool body 7. There is an iron molten metal channel 10 between the bottom of slag baffle B12 and the bottom of the inner cavity of the slag pool body 7.

[0039] A method for preparing a slag grate for a submerged arc furnace includes the following steps: Step 1: Welding of the slag grate shell Based on the different sizes of the slag grate designed on site, the outer shell is welded first, and vent holes are evenly distributed on the side wall of the outer shell; the vent holes are 20mm round holes, and the distance between the outer edges of two adjacent vent holes is 200mm; Step 2: Anchor welding The anchors are evenly distributed and firmly welded to the inner wall of the steel shell of the grate pool, with a spacing of 200-250mm. The anchors are American-style anchors with an inverted "V" shape, which have a large contact area with the steel shell, making the welding more secure and improving the gripping strength of the anchors. Step 3: Laying the refractory brick layer A layer of refractory bricks is laid on the base and side walls of the outer shell; Step 4: Formwork The mold shell is assembled and welded according to the internal cavity shape of the slag pool body, and then the mold is supported. Step 5: Preparation of Castable Refractories The raw materials used to prepare the castable and their weight proportions are as follows: 25 parts fused mullite, 20 parts tabular corundum, 2 parts andalusite, 3 parts alumina micro powder, 2 parts silicon carbide, 2 parts aluminate cement, 0.5 parts metallic silicon powder, 0.1 parts metallic aluminum powder, 0.1 parts boron carbide, 2 parts carbon source, 2 parts 316L stainless steel fiber; 0.2 parts sodium hexametaphosphate water-reducing agent, and 3 parts water. Among them, the fused mullite contains >75% alumina and has particle sizes of 5-8mm, 3-5mm, and 3-1mm, with a mass ratio of 2:3:5. Tabular corundum includes 0-1mm tabular corundum particles and 200-mesh and 325-mesh tabular corundum fine powders, with a mass ratio of 2:2:3. Andalusite contains ≥57% Al₂O₃ and has particle sizes of 3-1mm and ≤0.074mm, with a mass ratio of 2:1. Silicon carbide contains ≥98% SiC and has a particle size of 1-0mm. Boron carbide has a particle size ≤0.075mm. The carbon source is a composite carbon source of carbon black and pitch, with a mass ratio of 1:1. Prepare the raw materials according to the above proportions, put them into a mixer and mix for 3-5 minutes, then add water-reducing agent and water and mix for 10-15 minutes to form Al2O3-SiC-C castable. Step Six: Pouring The prepared Al2O3-SiC-C castable was poured into the inner cavity mold of the grate pool and the mold of the slag baffle plate, respectively. After vibration molding and curing at room temperature for 24-36 hours, the material was demolded. An anti-sticking agent was applied to the slag baffle plate. Step 7: Baking After demolding, bake at 150-170℃ for 73-74 hours before use. Example 2

[0040] The structure of a slag grate for a submerged arc furnace is the same as in Example 1.

[0041] A method for preparing a slag grate for a submerged arc furnace includes the following steps: Step 1: Welding of the slag grate shell Based on the different sizes of the slag grate designed on site, the outer shell is welded first, and vent holes are evenly distributed on the side wall of the outer shell; the vent holes are 20mm round holes, and the distance between the outer edges of two adjacent vent holes is 220mm. Step 2: Anchor welding The anchors are evenly distributed and firmly welded to the inner wall of the steel shell of the grate pool, with a spacing of 200-250mm. The anchors are American-style anchors with an inverted "V" shape, which have a large contact area with the steel shell, making the welding more secure and improving the gripping strength of the anchors. Step 3: Laying the refractory brick layer A layer of refractory bricks is laid on the base and side walls of the outer shell; Step 4: Formwork The model is assembled and welded according to the shape of the inner cavity of the slag pool, and then the formwork is erected. Step 5: Preparation of Castable Refractories The raw materials used to prepare the castable and their weight proportions are as follows: 35 parts fused mullite, 30 parts tabular corundum, 6 parts andalusite, 5 parts alumina micro powder, 6 parts silicon carbide, 5 parts aluminate cement, 1 part metallic silicon powder, 0.3 parts metallic aluminum powder, 0.3 parts boron carbide, 2.5 parts carbon source, 5 parts 316L stainless steel fiber; 0.45 parts water-reducing agent and 5 parts water. Among them, the fused mullite contains >75% alumina, and its particle size consists of three types: 5-8mm, 3-5mm, and 3-1mm, with a mass ratio of 3:2:4. The tabular corundum includes tabular corundum particles with a diameter of 0-1mm, and fine tabular corundum powders of 200 mesh and 325 mesh, with a mass ratio of 3:3:2. Andalusite contains ≥57% Al₂O₃, and its particle size consists of two types: 3-1mm and ≤0.074mm, with a mass ratio of 3:2. Silicon carbide contains ≥98% SiC with a particle size of 1-0mm; boron carbide has a particle size ≤0.075mm; the carbon source is a composite carbon source of carbon black and pitch, with a mass ratio of 1:1.2. Prepare the raw materials according to the above proportions, put them into a mixer and stir for 3-5 minutes, then add water-reducing agent and water and stir for 15-20 minutes to form Al2O3-SiC-C castable. Step Six: Pouring The prepared Al2O3-SiC-C castable was poured into the inner cavity mold of the grate pool and the mold of the slag baffle plate, respectively. After vibration molding and curing at room temperature for 36-40 hours, the mold was demolded. An anti-sticking agent was applied to the slag baffle plate. Step 7: Baking After demolding, bake at 180-200℃ for 72-74 hours before use. Example 3

[0042] The structure of a slag grate for a submerged arc furnace is the same as in Example 1.

[0043] A method for preparing a slag grate for a submerged arc furnace includes the following steps: Step 1: Welding of the slag grate shell Based on the different sizes of the slag grate designed on site, the outer shell is welded first, and vent holes are evenly distributed on the side wall of the outer shell; the vent holes are 20mm round holes, and the distance between the outer edges of two adjacent vent holes is 250mm. Step 2: Anchor welding The anchors are evenly distributed and firmly welded to the inner wall of the steel shell of the grate pool, with a spacing of 200-250mm. The anchors are American-style anchors with an inverted "V" shape, which have a large contact area with the steel shell, making the welding more secure and improving the gripping strength of the anchors. Step 3: Laying the refractory brick layer A layer of refractory bricks is laid on the base and side walls of the outer shell; Step 4: Formwork The model is assembled and welded according to the shape of the inner cavity of the slag pool, and then the formwork is erected. Step 5: Preparation of Castable Refractories The raw materials used to prepare the castable and their weight proportions are as follows: 45 parts fused mullite, 45 parts tabular corundum, 10 parts andalusite, 8 parts alumina micro powder, 10 parts silicon carbide, 8 parts aluminate cement, 1.5 parts metallic silicon powder, 0.45 parts metallic aluminum powder, 0.5 parts boron carbide, 3 parts carbon source, 7 parts 316L stainless steel fiber; 0.6 parts of water-reducing agents sodium hexametaphosphate and sodium tripolyphosphate, and 8 parts of water. Among them, the fused mullite contains >75% alumina, and its particle size consists of three types: 5-8mm, 3-5mm, and 3-1mm, with a mass ratio of 4:3:5. The tabular corundum includes tabular corundum particles with a diameter of 0-1mm, and fine tabular corundum powders of 200 mesh and 325 mesh, with a mass ratio of 4:3:3. Andalusite contains ≥57% Al₂O₃, and its particle size consists of two types: 3-1mm and ≤0.074mm, with a mass ratio of 3:2. Silicon carbide contains ≥98% SiC with a particle size of 1-0mm; boron carbide has a particle size ≤0.075mm; the carbon source is a composite carbon source of carbon black and pitch, with a mass ratio of 1:1.5. Prepare the raw materials according to the above proportions, put them into a mixer and mix for 3-5 minutes, then add water-reducing agent and water and mix for 20-30 minutes to form Al2O3-SiC-C castable. Step Six: Pouring The prepared Al2O3-SiC-C castable was poured into the inner cavity mold of the grate pool and the mold of the slag baffle plate, respectively. After vibration molding and curing at room temperature for 40-48 hours, the mold was demolded. An anti-sticking agent was sprayed on the slag baffle plate. Step 7: Baking After demolding, bake at 200-220℃ for 70-72 hours before use.

[0044] Chemical composition analysis and performance testing were performed on the castable samples prepared in Examples 1-3. The chemical composition was: Al2O3 ≥ 75 wt%, SiC ≥ 15 wt%, C ≥ 2 wt%. The main performance indicators of the castables are shown in the table below:

[0045] The above embodiments are merely examples illustrating the explanation, specific implementation, and effects of the present invention, and are not intended to limit the invention. Based on this disclosure, some modifications or improvements without contributing any inventive step can be made, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of this disclosure fall within the scope of protection claimed in this disclosure.

Claims

1. A slag grate for a submerged arc furnace, characterized in that: The system includes a slag grate pool, which has an open-top rectangular steel shell. The shell is welded together from a base and four side walls. Refractory brick layers are laid on the base and side walls. The slag grate pool body, cast from refractory refractory material, is placed on top of the refractory brick layers. The bottom of the inner cavity of the slag grate pool body is a rectangular recessed bottom. Along the length of the slag grate pool body, the upper end of the inner cavity has an iron inlet channel, and the lower end has an iron outlet channel. The two sides of the inner cavity of the slag grate pool body extend upward and outward from the recessed opening at the bottom, forming a smooth, sloping side. The left side of the inner cavity of the slag grate pool body extends upward from the bottom to form a hump-shaped left edge, and the right side extends upward from the bottom to form a flat right edge. A slag baffle plate is placed horizontally inside the inner cavity of the slag grate pool body, and an arc-shaped lifting ring is fixed at the top center of the baffle plate.

2. The slag grate for a submerged arc furnace according to claim 1, characterized in that: The molten iron inlet channel is connected to the main iron trough. The bottom of the molten iron inlet channel is arc-shaped, smoothly transitioning upwards with a slope. The molten iron outlet channel is connected to the branch iron trough. The bottom of the molten iron outlet channel is flat, smoothly transitioning upwards on both sides with a slope. The cross-sections of both the molten iron inlet channel and the molten iron outlet channel are trapezoidal, with rounded transitions at the four corners.

3. A slag grate for a submerged arc furnace according to claim 1, characterized in that: The bottom height of the molten iron inlet channel is less than the bottom height of the molten iron outlet channel; at the same horizontal level, the width of the molten iron inlet channel is greater than the width of the molten iron outlet channel; the bottom height of the molten iron outlet channel is 200mm lower than the height of the slag discharge groove; the iron support trough connected to the molten iron outlet channel has a downward tilt angle of 13°.

4. A slag grate for a submerged arc furnace according to claim 1, characterized in that: The left side of the inner cavity of the grate pool has a flange surface that protrudes in the middle and on both sides, and the two sides of the middle flange surface have recessed slag discharge grooves; the height of the flange surface is the same as the height of the right side edge; the height of the slag discharge groove is less than the bottom height of the molten iron outlet channel; at the same height level, the width of the slag discharge groove near the molten iron inlet channel is greater than the width of the slag discharge groove at the molten iron outlet channel.

5. A slag grate for a submerged arc furnace according to claim 1, characterized in that: The outer sidewall of the grate pool is higher than the refractory brick layer, and the height of the cast grate pool body is the same as the height of the outer sidewall of the grate pool.

6. A slag grate for a submerged arc furnace according to claim 1, characterized in that: There are two types of slag baffles: slag baffle A and slag baffle B. Slag baffle A has a square cross-section and is a long strip with a rectangular cross-section and a trapezoidal longitudinal section. The width of slag baffle A is the same as the width of slag baffle B. The slope of the trapezoid of slag baffle B is the same as the slope of the two sides of the inner cavity of the grate pool. There is a channel for molten iron between the bottom of slag baffle B and the bottom of the inner cavity of the grate pool.

7. A method for preparing a slag grate for a submerged arc furnace as described in claim 1, characterized in that: Includes the following steps: Step 1: Welding of the slag grate shell Based on the different sizes of the slag grate designed on site, the outer shell is welded first, and vent holes are evenly distributed on the side wall of the outer shell; the vent holes are 20mm round holes, and the distance between the outer edges of two adjacent vent holes is 200-250mm; Step 2: Anchor welding The anchors are evenly distributed and firmly welded to the inner wall of the steel outer shell of the slag pool, with a spacing of 200-250mm; the anchors are American-style anchors in the shape of an inverted "V". Step 3: Laying the Refractory Brick Layer A layer of refractory bricks is laid on the base and side walls of the outer shell; Step 4: Formwork The model is assembled and welded according to the shape of the inner cavity of the slag pool, and then the formwork is erected. Step 5: Preparation of Castable Refractories The raw materials used in the preparation of the castable and their weight proportions are as follows: 25-45 parts fused mullite, 20-45 parts tabular corundum, 2-10 parts andalusite, 3-8 parts alumina powder, 2-10 parts silicon carbide, 2-8 parts aluminate cement, 0.5-1.5 parts metallic silicon powder, 0.1-0.45 parts metallic aluminum powder, 0.1-0.5 parts boron carbide, 2-3 parts carbon source, 2-7 parts 316L stainless steel fiber; 0.2-0.6 parts water-reducing agent, and 3-8 parts water. Prepare the raw materials according to the above proportions, put them into a mixer and mix for 3-5 minutes, then add water-reducing agent and water and mix for 10-30 minutes to form Al2O3-SiC-C castable. Step Six: Pouring The prepared Al2O3-SiC-C castable was poured into the inner cavity mold of the grate pool and the mold of the slag baffle plate, respectively. After vibration molding and curing at room temperature for 24-48 hours, the material was demolded. An anti-sticking agent was sprayed or applied to the slag baffle plate. Step 7: Baking After demolding, bake at 150-220℃ for 70-74 hours before use.

8. The method for preparing a slag grate for a submerged arc furnace according to claim 7, characterized in that: In step five, the alumina content in the fused mullite is >75%, and the particle size of the fused mullite consists of three types: 5-8mm, 3-5mm, and 3-1mm, with a mass ratio of 1-4:1-3:3-5. Tabular corundum includes tabular corundum particles with a particle size of 0-1 mm, and 200-mesh and 325-mesh tabular corundum fine powder, with a mass ratio of 2-4:2-3:1-3.

9. The method for preparing a slag grate for a submerged arc furnace according to claim 7, characterized in that: In step five, the SiC content in silicon carbide is ≥98%, and the particle size is 1-0 mm; the particle size of boron carbide is ≤0.075 mm.

10. A method for preparing a slag grate for a submerged arc furnace according to claim 7, characterized in that: In step five, the andalusite consists of two particle sizes: 3-1 mm and ≤0.074 mm, with a mass ratio of 2-4:1-2; the AL2O3 content in the andalusite is ≥57%; the carbon source is a composite carbon source of carbon black and spherical pitch, with a mass ratio of 1:1-1.5; and the water-reducing agent is at least one of sodium hexametaphosphate and sodium tripolyphosphate.

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