Stopper rod refractory material special for high-grade silicon steel and preparation method of stopper rod refractory material

Abstract

The invention discloses a special stopper rod refractory material for high-grade silicon steel, which comprises the following components in percentage by weight: 23 to 27 percent of graphite, 23 to 27 percent of white corundum, 10 to 14 percent of shale ceramsite, 16 to 20 percent of alumina powder, 4 to 8 percent of fused quartz, 5 to 9 percent of calcium zirconate, 2 to 7 percent of metal silicon powder, 2.5 to 7.5 percent of boron oxide, 4 to 8 percent of silicon nitride and 0.3 to 0.7 percent of polypropylene fiber. And 12%-16% of phenolic resin. According to the stopper rod refractory special for the high-grade silicon steel and the preparation method of the stopper rod refractory, the continuous casting time of a tundish is long, a continuous casting functional refractory does not need to be replaced midway, and nitrogen increase and foreign matter inclusion of molten steel are prevented.

Description

Technical Field

[0001] The present invention relates to the field of inorganic non-metallic refractory materials, and more specifically to a high-grade silicon steel special stopper rod refractory and a preparation method thereof. Background Art

[0002] After the 20th century, with the technological progress of countries around the world, the requirements for steel performance have become increasingly stringent, and various studies have shown that when the impurities in steel are reduced to a certain level, the performance of the steel will have a qualitative leap. Therefore, more and more types of steel have emerged, and the continuous casting process requirements of these steels are becoming more and more stringent, requiring continuous casting refractory materials to not only meet the service life, but also have certain special functions.

[0003] With the development and progress of smelting technology, the cleanliness level of steel is constantly improving. Taking the content of [C], [P], [S], [H], [N], and [O] in steel as an example, in developed Western countries, the total amount of impurities in molten steel is required to be controlled below 35ppm. In the entire billet continuous casting process, the stopper rod plays the role of a valve to control the opening and closing of the molten steel and the pulling speed. However, with the optimization of steel grades and the continuous transformation to high-quality steel, the requirements for smelting level are getting higher and higher, and at the same time, the requirements for the three major refractory materials for continuous casting are also more stringent. During casting, it is necessary to ensure a high number of continuous casting furnaces, and at the same time, the inner hole of the tundish upper water inlet and the inner hole of the immersion water inlet should not be blocked during the casting process. During the casting process, the liquid level in the crystallizer also needs to be kept active to facilitate the floating of inclusions in the molten steel and the protection slag to facilitate impurity removal. However, the argon pressure cannot be too large, which is not conducive to the formation of the shell of the continuous casting billet, and it is also easy to affect the slag, and even cause slag rolling accidents.

[0004] At the same time, the demand for smelting high-performance steels such as automobiles, special military steels, silicon steels, and automobile plates places high demands on the control of foreign matter inclusions in molten steel. If the content of other harmful elements such as alumina exceeds the standard, it can only be downgraded. It can be seen that there is a lack of stopper refractory materials on the market that can effectively solve the problems of blockage of the inner holes of the water inlet and the immersion water inlet, impurity removal of molten steel in the crystallizer, and life of the stopper rod in high continuous casting furnaces. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a high-grade silicon steel special stopper rod refractory and its preparation method, which has a long continuous casting time in the ladle, does not need to replace the continuous casting functional refractory during the process, and prevents nitrogen increase and foreign matter inclusion in the molten steel.

[0006] According to one aspect of the present invention, there is provided a high-grade silicon steel stopper rod refractory, which comprises the following components in weight percentage: 23%-27% graphite, 23%-27% white corundum, 10%-14% shale ceramsite, 16%-20% alumina powder, 4%-8% fused quartz, 5%-9% calcium zirconate, 2%-7% metallic silicon powder, 2.5%-7.5% boron oxide, 4%-8% silicon nitride and 0.3%-0.7% polypropylene fiber, plus 12%-16% phenolic resin.

[0007] In some embodiments, the graphite specifications are: +198;

[0008] The specifications of white corundum are: particle size 36#-70# and particle size 200#;

[0009] The specifications of shale ceramsite are: particle size 36#;

[0010] Alumina powder particle size: 10-50μm;

[0011] The specifications of fused quartz are: particle size 36#-70#;

[0012] The specifications of calcium zirconate are: particle size 36#-70# and particle size 70#;

[0013] The particle size of metal silicon powder is: 200 mesh;

[0014] Boron oxide particle size: 200 mesh;

[0015] The particle size of silicon nitride is: 200 mesh.

[0016] In some embodiments, the weight percentage of the white corundum with a particle size of 36#-70# is 15%, and the weight percentage of the white corundum with a particle size of 36#-70# is 10%.

[0017] In some embodiments, the weight percentage of calcium zirconate with a particle size of 36#-70# is 4%, and the weight percentage of calcium zirconate with a particle size of 70# is 3%.

[0018] In some embodiments, the rod comprises a rod head, a rod body and a small-flow air-permeable core, the rod body is provided with a through air inlet hole along the axis, the rod head is fixed at the front end of the rod body, the small-flow air-permeable core is installed at the end of the air inlet hole away from the rod head, a directional blowing hole connected to the air inlet hole is provided in the rod head, and the aperture of the directional blowing hole is 1.8mm-2mm.

[0019] According to one aspect of the present invention, a method for preparing a high-grade silicon steel stopper rod refractory is provided, comprising the following steps:

[0020] S1. Raw material selection;

[0021] S2, ingredients, add each group of ingredients according to the proportion;

[0022] S3, mixing and granulating, using a granulator to mix and granulate;

[0023] S4, screening, using a vibrating screen to screen the granulation raw materials;

[0024] S5, trapping the material, sealing 75% of the raw materials;

[0025] S6, mixing, using a planetary mixing device to mix the trapped raw materials and the remaining 25% of the raw materials evenly;

[0026] S7. Check and determine the particle size and moisture content of the mixed raw materials;

[0027] S8, forming, using die-casting equipment to press the mixed principle into a stopper rod blank;

[0028] S9, drying, drying the formed stopper rod blank;

[0029] S10, firing, pushing the stopper rod blank into a high-temperature tunnel kiln for firing, and then cooling to room temperature before taking it out of the kiln;

[0030] S11, processing, processing the outer circle and rolling line thickness of the stopper rod;

[0031] S12, spraying, spraying glaze on the outside of the stopper rod using an automatic glaze dipping device;

[0032] S13. Inspection: Check the appearance, size and physical and chemical indicators of the finished product;

[0033] S14. Qualified products are packaged and put into storage, and unqualified products are destroyed.

[0034] In some embodiments, in S3, the raw materials need to be premixed and preheated before kneading. The premixing is performed by mixing the raw materials with a stirring device and preheating the premixed raw materials at a temperature of 70°C-80°C.

[0035] In some embodiments, in S5, 75% of the raw materials are placed in a silo or a material trap and covered with plastic sheeting to ensure that the raw materials do not come into contact with water. The temperature should be greater than 15° C. and the raw materials are left to stand for more than 24 hours.

[0036] In some embodiments, in step S8, the raw materials need to be pressed under a constant temperature and humidity state, and the cold isostatic pressing time is 2 minutes.

[0037] In some embodiments, the drying in step S9 includes natural drying and heat drying, wherein the natural drying is drying at room temperature above 15°C for more than 6 hours, and the heat drying is drying in a heating kiln at 110°C-150°C for 1-2 hours.

[0038] In some embodiments, firing comprises the following steps:

[0039] S1, loading, pushing the stopper rod blank into the high temperature tunnel kiln;

[0040] S2, heating, uniformly heating to 650℃-780℃ within 5 hours;

[0041] S3, high temperature firing, high temperature tunnel kiln is heated to 1650-1750℃ within 4 hours;

[0042] S4, heat preservation, firing at 1650-1750℃ for 18-24 hours;

[0043] S5, cooling, uniformly cooling to 150℃-200℃ within 8 hours;

[0044] S6. Cooling: Cooling to room temperature and taking the fired stopper rod out of the kiln.

[0045] The invention discloses a special stopper rod refractory for high-grade silicon steel, which has the following beneficial effects: long continuous casting time of the tundish, no need to replace the continuous casting functional refractory during the process, and prevention of nitrogen increase in molten steel and inclusion of foreign matter. Through the use of small flow rate and high back pressure 2mm hole argon blowing plug rod, matching with connectors, small flow rate breathable core and other technologies, according to the use requirements of argon blowing plug rod process, magnesium aluminum spinel-carbon material is used to improve the erosion and scouring performance, and this material has the function of high furnace casting; the rod head adopts a set 2mm aperture directional pinhole small flow rate and small bubble argon blowing to purge the bowl mouth and inner cavity of the middle ladle to prevent the alumina adsorbent from agglomerating at the bowl mouth and inner cavity of the water mouth, causing molten steel inclusions and liquid level fluctuations, affecting the quality of high-specification silicon steel billets; through the set rod head 2mm aperture directional pinhole and small flow rate breathable core, the rod head adopts magnesium aluminum spinel-carbon material combination under small flow rate and small bubble argon blowing, reduce the bowl mouth and inner cavity nodules, reduce foreign matter inclusions in molten steel, reduce molten steel level fluctuations, and improve the quality and service life of clean steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of the structure of the high-grade silicon steel special stopper rod refractory of the present invention;

[0047] Figure 2 This is a process flow chart of the preparation method of the high-grade silicon steel special stopper rod refractory material of the present invention. DETAILED DESCRIPTION

[0048] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and equivalent changes or substitutions in functions, methods or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that, unless otherwise specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection of two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meaning of the terms can be understood according to the specific circumstances.

[0050] like Figure 1 As shown, a high-grade silicon steel special stopper rod refractory material includes a rod head 1, a rod body 2 and a small flow air permeable core 3. The rod body 2 is provided with a through air inlet 4 along the axis. The rod head 1 is fixed at the front end of the rod body 2. The small flow air permeable core 3 is installed at the end of the air inlet 4 away from the rod head 1. A directional blowing hole 5 connected to the air inlet 4 is provided in the rod head 1. The aperture of the directional blowing hole 5 is 1.8mm-2mm. Through the small flow high back pressure 2mm hole argon blowing stopper rod, matching connectors, small flow air permeable core 3 and other technologies, according to the use requirements of the argon blowing stopper rod process, magnesium aluminum spinel-carbon material is used to improve the erosion and scouring performance. The material has the function of high furnace casting. The rod head 1 adopts a set 2mm aperture directional pinhole small flow, small bubble argon blowing to purge the water mouth bowl mouth and inner cavity of the middle package to prevent the alumina adsorbed material from forming nodules on the water mouth bowl mouth and inner cavity, causing molten steel inclusions and liquid level fluctuations, affecting the quality of high-specification silicon steel billets.

[0051] During the implementation process, argon is blown at a low flow rate through the 2mm directional hole of the rod head to purge the bowl mouth and the plug rod head 1 to prevent the alumina adsorbent from agglomerating at the water inlet bowl mouth and the plug rod head 1, and reduce the inclusion of foreign matter in the molten steel. At the same time, the fluctuation of the molten steel level is reduced to improve the quality of clean steel; at the same time, the argon blowing flow rate of the rod head 1 is 1L / min, ensuring that the back pressure is in the range of 0.5bar-2.0bar. The plug rod opening is in the range of 50%-80%. Under the above conditions, the number of furnaces used for the plug rod on high-grade silicon steel varieties above 94 has increased from 5 to more than 10.

[0052] A high-grade silicon steel special stopper rod refractory material comprises the following components in weight percentage: 23%-27% graphite, 23%-27% white corundum, 10%-14% shale ceramsite, 16%-20% alumina powder, 4%-8% fused quartz, 5%-9% calcium zirconate, 2%-7% metallic silicon powder, 2.5%-7.5% boron oxide, 4%-8% silicon nitride and 0.3%-0.7% polypropylene fiber, and 12%-16% phenolic resin.

[0053] Graphite specifications: +198;

[0054] The specifications of white corundum are: particle size 36#-70# and particle size 200#;

[0055] The specifications of shale ceramsite are: particle size 36#;

[0056] Alumina powder particle size: 10-50μm;

[0057] The specifications of fused quartz are: particle size 36#-70#;

[0058] The specifications of calcium zirconate are: particle size 36#-70# and particle size 70#;

[0059] The particle size of metal silicon powder is: 200 mesh;

[0060] Boron oxide particle size: 200 mesh;

[0061] The particle size of silicon nitride is: 200 mesh.

[0062] The weight percentage of the white corundum with a particle size of 36#-70# is 15%, and the weight percentage of the white corundum with a particle size of 36#-70# is 10%.

[0063] The weight percentage of calcium zirconate with a particle size of 36#-70# is 4%, and the weight percentage of calcium zirconate with a particle size of 70# is 3%.

[0064] During the specific implementation process, the proportions should be made according to the table below.

[0065]

[0066] like Figure 2 As shown, a method for preparing a high-grade silicon steel special stopper rod refractory comprises the following steps:

[0067] S1. Raw material selection;

[0068] S2, ingredients, add each group of ingredients according to the proportion;

[0069] S3, mixing and granulating, using a granulator to mix and granulate;

[0070] S4, screening, using a vibrating screen to screen the granulation raw materials;

[0071] S5, trapping the material, sealing 75% of the raw materials;

[0072] S6, mixing, using a planetary mixing device to mix the trapped raw materials and the remaining 25% of the raw materials evenly;

[0073] S7. Check and determine the particle size and moisture content of the mixed raw materials;

[0074] S8, forming, using die-casting equipment to press the mixed principle into a stopper rod blank;

[0075] S9, drying, drying the formed stopper rod blank;

[0076] S10, firing, pushing the stopper rod blank into a high-temperature tunnel kiln for firing, and then cooling to room temperature before taking it out of the kiln;

[0077] S11, processing, processing the outer circle and rolling line thickness of the stopper rod;

[0078] S12, spraying, spraying glaze on the outside of the stopper rod using an automatic glaze dipping device;

[0079] S13. Inspection: Check the appearance, size and physical and chemical indicators of the finished product;

[0080] S14. Qualified products are packaged and put into storage, and unqualified products are destroyed.

[0081] In S3, the raw materials need to be premixed and preheated before kneading. The premixing is performed by mixing the raw materials with a stirring device and preheating the premixed raw materials at a temperature of 70° C. to 80° C.

[0082] In S5, 75% of the raw materials are placed in a silo or a material storage area and covered with plastic sheeting to ensure that the raw materials do not come into contact with water. The temperature should be greater than 15°C and the material is left to stand for more than 24 hours.

[0083] In step S8, the raw materials need to be pressed under a constant temperature and humidity state, and the cold isostatic pressing time is 2 minutes.

[0084] The drying in step S9 includes natural drying and heating drying. The natural drying is drying at room temperature above 15° C. for more than 6 hours, and the heating drying is drying in a heating kiln at 110° C.-150° C. for 1-2 hours.

[0085] Firing includes the following steps:

[0086] S1, loading, pushing the stopper rod blank into the high temperature tunnel kiln;

[0087] S2, heating, uniformly heating to 650℃-780℃ within 5 hours;

[0088] S3, high temperature firing, high temperature tunnel kiln is heated to 1650-1750℃ within 4 hours;

[0089] S4, heat preservation, firing at 1650-1750℃ for 18-24 hours;

[0090] S5, cooling, uniformly cooling to 150℃-200℃ within 8 hours;

[0091] S6. Cooling: Cooling to room temperature and taking the fired stopper rod out of the kiln.

[0092] Through the above steps, the indicators in the following table can be achieved.

[0093]

[0094]

[0095] The above are only some embodiments of the present invention. It should be pointed out that for ordinary technicians in this field, other modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. High-grade silicon steel special plug rod refractory, characterized by: Calculated by weight percentage, the invention comprises the following components: 23%-27% graphite, 23%-27% white corundum, 10%-14% shale ceramsite, 16%-20% alumina powder, 4%-8% fused quartz, 5%-9% calcium zirconate, 2%-7% metallic silicon powder, 2.5%-7.5% boron oxide, 4%-8% silicon nitride and 0.3%-0.7% polypropylene fiber, and 12%-16% phenolic resin.

2. The high-grade silicon steel stopper rod refractory according to claim 1 is characterized in that: The graphite specifications are: +198; The specifications of the white corundum are: particle size 36#-70# and particle size 200#; The specifications of the shale ceramsite are: particle size 36#; The particle size of the alumina powder is: 10-50 μm; The specifications of the fused quartz are: particle size 36#-70#; The calcium zirconate specifications are: particle size 36#-70# and particle size 70#; The particle size of the metal silicon powder is: 200 mesh; The particle size of the boron oxide is: 200 mesh; The silicon nitride particle size is: 200 mesh.

3. The high-grade silicon steel stopper rod refractory according to claim 2 is characterized in that: The weight percentage of the white corundum with a particle size of 36#-70# is 15%, and the weight percentage of the white corundum with a particle size of 36#-70# is 10%; The weight percentage of calcium zirconate with a particle size of 36#-70# is 4%, and the weight percentage of calcium zirconate with a particle size of 70# is 3%.

4. The high-grade silicon steel stopper rod refractory according to claim 2 is characterized in that: It includes a rod head, a rod body and a small-flow air-permeable core. The rod body is provided with a through air inlet hole along the axis. The rod head is fixed at the front end of the rod body. The small-flow air-permeable core is installed at the end of the air inlet hole away from the rod head. A directional blowing hole connected to the air inlet hole is provided in the rod head, and the aperture of the directional blowing hole is 1.8mm-2mm.

5. The method for preparing the high-grade silicon steel stopper rod refractory according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Raw material selection; S2, ingredients, add each group of ingredients according to the proportion; S3, mixing and granulating, using a granulator to mix and granulate; S4, screening, using a vibrating screen to screen the granulation raw materials; S5, trapping the material, sealing 75% of the raw materials; S6, mixing, using a planetary mixing device to mix the trapped raw materials and the remaining 25% of the raw materials evenly; S7. Check and determine the particle size and moisture content of the mixed raw materials; S8, forming, using die-casting equipment to press the mixed principle into a stopper rod blank; S9, drying, drying the formed stopper rod blank; S10, firing, pushing the stopper rod blank into a high-temperature tunnel kiln for firing, and then cooling to room temperature before taking it out of the kiln; S11, processing, processing the outer circle and rolling line thickness of the stopper rod; S12, spraying, spraying glaze on the outside of the stopper rod using an automatic glaze dipping device; S13. Inspection: Check the appearance, size and physical and chemical indicators of the finished product; S14. Qualified products are packaged and put into storage, and unqualified products are destroyed.

6. The method for preparing the high-grade silicon steel stopper rod refractory according to claim 5, characterized in that: In S3, the raw materials need to be premixed and preheated before kneading. The premixing is performed by mixing the raw materials through a stirring device and preheating the premixed raw materials at a temperature of 70° C. to 80° C.

7. The method for preparing the high-grade silicon steel stopper rod refractory according to claim 5, characterized in that: In S5, 75% of the raw materials are placed in a silo or a material trap and covered with plastic sheeting to ensure that the raw materials do not come into contact with water. The temperature should be greater than 15° C. and the raw materials are left to stand for more than 24 hours.

8. The method for preparing the high-grade silicon steel stopper rod refractory according to claim 5, characterized in that: In the step S8, the raw materials need to be pressed under a constant temperature and humidity, and the cold isostatic pressing time is 2 minutes.

9. The method for preparing the high-grade silicon steel stopper rod refractory according to claim 5, characterized in that: The drying in step S9 includes natural drying and heating drying. The natural drying is drying at room temperature above 15° C. for more than 6 hours, and the heating drying is drying in a heating kiln at 110° C.-150° C. for 1-2 hours.

10. The method for preparing the high-grade silicon steel stopper rod refractory according to claim 5, characterized in that: The firing comprises the following steps: S1, loading, pushing the stopper rod blank into the high temperature tunnel kiln; S2, heating, uniformly heating to 650℃-780℃ within 5 hours; S3, high temperature firing, the high temperature tunnel kiln is heated to 1650-1750℃ for firing within 4 hours; S4, heat preservation, heat preservation and firing at 1650-1750℃ for 18 hours to 24 hours; S5, cooling, uniformly cooling to 150℃-200℃ within 8 hours; S6. Cooling: Cooling to room temperature and taking the fired stopper rod out of the kiln.

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