Low-pressure molding long nozzle refractory material and preparation method thereof

Abstract

The invention discloses a low-pressure molding long nozzle refractory material which comprises the following components in percentage by weight: 8%-12% of flake graphite, 9%-13% of colloidal graphite, 33%-37% of alumina powder, 24%-30% of sub-white corundum, 12%-16% of zirconium mullite, 0.4%-0.6% of boron nitride, 0.8%-1.2% of monatomic silicon and 1.3%-1.7% of boric anhydride. Additionally, 4-8% of phenolic resin, 2-4% of furfural, 2-4% of curing agent and 6-10% of organic dispersing agent. The invention provides the low-pressure molding long nozzle refractory material which is long in service life, low in manufacturing cost and capable of shortening the production cycle of three major parts and simplifying the production process, and the preparation method of the low-pressure molding long nozzle refractory material.

Description

Technical Field

[0001] The present invention relates to the field of inorganic non-metallic refractory materials, and more specifically to a low-pressure formed long nozzle refractory material 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] At present, the domestic immersion nozzle mainly adopts high-pressure technology, with a molding pressure of 125MPa. The stability of the products pressed by this process is acceptable, but there are disadvantages. The production cycle is relatively long, and it takes 9 to 10 days from pressing to packaging and delivery. The higher pressure has certain damage to the isostatic press equipment and molds. There are gradient requirements for pressure increase and pressure relief. It takes 35 minutes to press a cylinder of immersion. Using low-pressure technology, the pressure is only 42MPa, and there is no need for pressure maintenance and pressure relief gradients. It only takes 4 minutes to press a cylinder of immersion. The lower pressure has less damage to the equipment and molds, which is not only efficient, but also cost-saving.

[0004] At the same time, the existing long shroud refractory materials need to go through the processes of drying and firing after forming, which has a long production cycle and high energy consumption.

[0005] As a result, with the increasing demand for special steel smelting in steel mills, high-quality, special-function continuous casting refractory materials have emerged. For this reason, the market currently lacks a low-pressure forming long nozzle that can be directly used for research and development. On the basis of shortening the production cycle of the three major parts and simplifying the production process, it can improve its service life, reduce manufacturing costs, and comprehensively meet the various complex use conditions of customers. It plays a guiding role in the development of composite continuous casting refractory materials and plays a decisive role in the subsequent development of similar high-tech refractory materials, because the long nozzle refractory materials can be directly put into use without gas baking. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a low-pressure formed long-gate refractory material and a preparation method thereof with long service life, low manufacturing cost, shortened three-piece production cycle and simplified production process.

[0007] According to one aspect of the present invention, there is provided a low-pressure forming long nozzle refractory material, which comprises the following components in weight percentage: 8%-12% flake graphite, 9%-13% colloidal graphite, 33%-37% alumina powder, 24%-30% sub-white corundum, 12%-16% zirconium mullite, 0.4%-0.6% boron nitride, 0.8%-1.2% elemental silicon and 1.3%-1.7% boric anhydride, in addition to: 4%-8% phenolic resin, 2%-4% furfural, 2%-4% curing agent and 6%-10% organic dispersant.

[0008] In some embodiments, the graphite specifications are: particle size 0.3 mm, moisture ≤ 0.5%;

[0009] Colloidal graphite specifications are: particle size 0.3mm, moisture ≤0.5%, fixed carbon content ≥94%;

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

[0011] The specifications of sub-white corundum are: particle size 36#-70#, particle size 120#-0# and particle size 200#-0#;

[0012] Zirconium mullite specifications: particle size 200 mesh-240 mesh;

[0013] The specifications of boron nitride are: particle size 1μm;

[0014] The specifications of elemental silicon are: particle size 300 mesh;

[0015] The particle size of boric anhydride is: 40 mesh.

[0016] In some embodiments, the weight percentage of sub-white corundum particles 36#-70# is 15%;

[0017] The weight percentage of sub-white corundum particle size 120#-0# is 5%;

[0018] The weight percentage of sub-white corundum with a particle size of 200#-0# is 7%.

[0019] In some embodiments, the curing agent is: m-phenylenediamine or diaminodiphenylmethane;

[0020] The organic dispersant is: alkyl aryl sulfonate.

[0021] 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.

[0022] According to one aspect of the present invention, there is provided a method for preparing a low pressure forming long shroud refractory, comprising the following steps:

[0023] S1. Raw material selection;

[0024] S2, ingredients, add each group of ingredients according to the proportion;

[0025] S3, mixing and granulating, using a granulator to mix and granulate;

[0026] S4, screening, using a vibrating screen to screen the granulation raw materials;

[0027] S5, trapping the material, sealing 75% of the raw materials;

[0028] S6, mixing, using a horizontal mixing device to mix the finished raw materials and the remaining 25% of the raw materials evenly;

[0029] S7, inspecting and determining the particle size, moisture content and green body density of the mixed raw materials;

[0030] S8, forming, using die-casting equipment to press the mixed raw materials into a long nozzle blank;

[0031] S9, natural curing, naturally drying the formed long nozzle blank;

[0032] S10, product classification, classify the long nozzle blanks according to different specifications and parameters;

[0033] S11, processing, processing the inner hole and outer dimensions of the long nozzle;

[0034] S12, spraying, spraying glaze on the outside of the long nozzle by using an automatic glaze dipping device;

[0035] S13, inspection, conduct flaw detection on the finished product through X-ray, and check the appearance, size and physical and chemical indicators of the finished product;

[0036] S14. Qualified products are packaged and put into storage, and unqualified products are destroyed.

[0037] 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.

[0038] In some embodiments, 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 air temperature should be greater than 15°C and the raw materials are left to stand for more than 24 hours. At the same time, constant temperature and humidity are required, and the mud is placed in multiple layers to achieve a reasonable combination of the mud materials and ensure the stability of the mud material indicators.

[0039] In some embodiments, in step S8, the size of the rubber sleeve is appropriately adjusted according to the shrinkage ratio of various clay materials to reduce processing allowance or eliminate processing; the molding core mold is made of lightweight metal and is formed at low pressure while ensuring hardness.

[0040] In some embodiments, in step S9, the formed green body is placed in a natural environment for 24 hours to wait for solidification.

[0041] The low-pressure formed shroud refractory material disclosed in the present invention has the beneficial effects of long service life, low manufacturing cost, shortening the production cycle of three major parts and simplifying the production process. Through the use of technical processes, the steel plant cooperates with the optimization of baking conditions, and adjusts the materials of the shroud lining and slag line to ensure that the shroud lining has good thermal shock resistance and erosion resistance, while improving the corrosion resistance of the zirconium slag line. In the past, the average service life of a small shroud was 6 hours, but now its service life is required to be ≥8 hours; the average service life of a single slag line of a shroud is 4 hours, and now the steel plant requires the service life of a single slag line to be ≥5 hours. DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with various embodiments, 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.

[0043] 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.

[0044] A low-pressure formed long nozzle refractory material comprises the following components by weight percentage: 8%-12% of flake graphite, 9%-13% of colloidal graphite, 33%-37% of alumina powder, 24%-30% of sub-white corundum, 12%-16% of zirconium mullite, 0.4%-0.6% of boron nitride, 0.8%-1.2% of elemental silicon and 1.3%-1.7% of boric anhydride, and in addition: 4%-8% of phenolic resin, 2%-4% of furfural, 2%-4% of curing agent and 6%-10% of organic dispersant.

[0045] Graphite specifications: particle size 0.3mm, moisture ≤0.5%;

[0046] Colloidal graphite specifications are: particle size 0.3mm, moisture ≤0.5%, fixed carbon content ≥94%;

[0047] Alumina powder particle size: 10-50μm;

[0048] The specifications of sub-white corundum are: particle size 36#-70#, particle size 120#-0# and particle size 200#-0#;

[0049] Zirconium mullite specifications: particle size 200 mesh-240 mesh;

[0050] The specifications of boron nitride are: particle size 1μm;

[0051] The specifications of elemental silicon are: particle size 300 mesh;

[0052] The particle size of boric anhydride is: 40 mesh.

[0053] The weight percentage of sub-white corundum with particle size of 36#-70# is 15%;

[0054] The weight percentage of sub-white corundum particle size 120#-0# is 5%;

[0055] The weight percentage of sub-white corundum with a particle size of 200#-0# is 7%.

[0056] After testing, the following table shows the optimal ingredient ratio.

[0057]

[0058] Curing agent: m-phenylenediamine or diaminodiphenylmethane; m-phenylenediamine or (NH2)2C6H4, molecular weight 107, active hydrogen equivalent 26.7, white crystal, melting point 62℃, 14-16 parts per 100 parts of standard resin. Curing at 60℃ for 2 hours + 150℃ for 2 hours. Applicable period 500g 50℃ for 2.5 hours, heat deformation temperature 150℃, bending strength 1050kg / cm2, compressive strength 710kg / cm2, tensile strength 540kg / cm2, elongation 3.0%, impact strength 0.2-0.3 feet-pounds / inch, Rockwell hardness 108. Dielectric constant (50 Hz 23℃) 3.3, power factor (50 Hz 23℃) 0.007, excellent heat resistance and corrosion resistance, good electrical properties, low toxicity. Because it is solid, it is inconvenient to use, and care should be taken to prevent gelation when heating and mixing with resin. Diaminodiphenylmethane [(NH2)(CH3)C6H4]2CH2, molecular weight 196, active hydrogen equivalent 49, white crystal, brown after long-term exposure to sunlight, melting point 89℃, 25-30 parts per 100 parts of standard resin. Curing 60℃ 2 hours + 150℃ 2 hours. Applicable period 500g 50℃ 3 hours, heat deformation temperature 145-150℃, bending strength 1190kg / cm2, compressive strength 710kg / cm2, tensile strength 550kg / cm2, elongation 4.4%, impact strength 0.3-0.5 feet-pounds / inch Rockwell hardness 106. Dielectric constant (50 Hz 23℃) 4.4, power factor (50 Hz 23℃) 0.004, volume resistivity greater than 1015Ω.cm, excellent heat resistance and corrosion resistance, good electrical properties, low toxicity. High heat resistance and mechanical strength. Because it is solid, it is not convenient to use. When mixing with resin, care must be taken to prevent gelation. These two curing agents have relatively good heat resistance and are convenient for use under high temperature conditions. By adding a special curing agent, it is not necessary to bake in an oven and sinter at high temperature to produce higher strength.

[0059] Organic dispersants are alkyl aryl sulfonates. Organic dispersants are used to disperse the raw material particles and improve process efficiency.

[0060] According to one aspect of the present invention, there is provided a method for preparing a low pressure forming long shroud refractory, comprising the following steps:

[0061] S1. Raw material selection;

[0062] S2, ingredients, add each group of ingredients according to the proportion;

[0063] S3, mixing and granulating, using a granulator to mix and granulate;

[0064] S4, screening, using a vibrating screen to screen the granulation raw materials;

[0065] S5, trapping the material, sealing 75% of the raw materials;

[0066] S6, mixing, using a horizontal mixing device to mix the finished raw materials and the remaining 25% of the raw materials evenly;

[0067] S7, inspecting and determining the particle size, moisture content and green body density of the mixed raw materials;

[0068] S8, forming, using die-casting equipment to press the mixed raw materials into a long nozzle blank;

[0069] S9, natural curing, naturally drying the formed long nozzle blank;

[0070] S10, product classification, classify the long nozzle blanks according to different specifications and parameters;

[0071] S11, processing, processing the inner hole and outer dimensions of the long nozzle;

[0072] S12, spraying, spraying glaze on the outside of the long nozzle by using an automatic glaze dipping device;

[0073] S13, inspection, conduct flaw detection on the finished product through X-ray, and check the appearance, size and physical and chemical indicators of the finished product;

[0074] S14. Qualified products are packaged and put into storage, and unqualified products are destroyed.

[0075] 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.

[0076] In S5, 75% of the raw materials are placed in a silo or material storage area and covered with plastic sheeting to ensure that the raw materials do not come into contact with water. The air temperature should be greater than 15°C and left to stand for more than 24 hours. At the same time, constant temperature and humidity are required, and the clay is placed in multiple layers to achieve a reasonable combination of clay materials and ensure the stability of clay material indicators.

[0077] In step S8, the size of the rubber sleeve is appropriately adjusted according to the shrinkage ratio of various clay materials to reduce processing allowance or eliminate processing; the molding core mold is made of lightweight metal and is formed at low pressure while ensuring hardness.

[0078] In step S9, the formed green body is placed in a natural environment for 24 hours to wait for solidification.

[0079] During implementation, we also need to pay attention to:

[0080] Control the moisture content of the mud. Under lower pressure, the product needs to reach a fixed strength.

[0081] The original high-pressure molding isostatic press's pressurization and pressure relief modes cannot meet the low-pressure molding process. It is necessary to use the American imported wet bag isostatic press, which has faster pressurization and pressure relief, and will not crack when pressing the low-pressure long nozzle;

[0082] The design of the mold, some products with long nozzles in low-pressure molding can be free of processing, and other products can be less processed. The size requirements are high, so the mold design and high-pressure immersion mold requirements are high;

[0083] The moisture content of granulating mud is more stringent, with a smaller fluctuation range, accurate to ±0.03%.

[0084] 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. Low pressure forming long shroud refractory, characterized by: Calculated by weight percentage, the invention comprises the following components: 8%-12% of flake graphite, 9%-13% of colloidal graphite, 33%-37% of alumina powder, 24%-30% of sub-white corundum, 12%-16% of zirconium mullite, 0.4%-0.6% of boron nitride, 0.8%-1.2% of elemental silicon and 1.3%-1.7% of boric anhydride, and in addition: 4%-8% of phenolic resin, 2%-4% of furfural, 2%-4% of curing agent and 6%-10% of organic dispersant.

2. The low pressure forming long shroud refractory according to claim 1, characterized in that: The graphite specifications are: particle size 0.3mm, moisture ≤0.5%; The colloidal graphite specifications are: particle size 0.3mm, moisture ≤0.5%, fixed carbon content ≥94%; The particle size of the alumina powder is: 10-50 μm; The sub-white corundum specifications are: particle size 36#-70#, particle size 120#-0# and particle size 200#-0#; The specifications of the zirconium mullite are: particle size 200 mesh-240 mesh; The boron nitride specifications are: particle size 1 μm; The specifications of the elemental silicon are: particle size 300 mesh; The particle size of the boric anhydride is 40 mesh.

3. The low pressure forming long shroud refractory according to claim 2, characterized in that: The weight percentage of the sub-white corundum particle size 36#-70# is 15%; The weight percentage of the sub-white corundum particle size 120#-0# is 5%; The weight percentage of the sub-white corundum with a particle size of 200#-0# is 7%.

4. The low pressure forming long shroud refractory according to claim 3, characterized in that: The curing agent is: m-phenylenediamine or diaminodiphenylmethane; The organic dispersant is: alkyl aryl sulfonate.

5. The method for preparing a low pressure forming long shroud 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 horizontal mixing device to mix the finished raw materials and the remaining 25% of the raw materials evenly; S7, inspecting and determining the particle size, moisture content and green body density of the mixed raw materials; S8, forming, using die-casting equipment to press the mixed raw materials into a long nozzle blank; S9, natural curing, naturally drying the formed long nozzle blank; S10, product classification, classify the long nozzle blanks according to different specifications and parameters; S11, processing, processing the inner hole and outer dimensions of the long nozzle; S12, spraying, spraying glaze on the outside of the long nozzle by using an automatic glaze dipping device; S13, inspection, conduct flaw detection on the finished product through X-ray, and 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 a low pressure forming long shroud 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 a low pressure forming long shroud refractory according to claim 5, characterized in that: In the 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 air temperature should be greater than 15°C and the raw materials are left to stand for more than 24 hours. At the same time, constant temperature and humidity are required, and the mud is placed in multiple layers to achieve a reasonable combination of mud materials and ensure the stability of mud material indicators.

8. The method for preparing a low pressure forming long shroud refractory according to claim 5, characterized in that: In the mixing step S6, the clay materials are mixed according to the process and then specially assigned to mix them. Then, samples are taken to make test blocks to ensure that the clay materials used are all qualified.

9. The method for preparing a low pressure forming long shroud refractory according to claim 5, characterized in that: In the step S8, the size of the rubber sleeve is appropriately adjusted according to the shrinkage ratio of various clay materials to reduce the processing allowance or achieve no processing; the molding core mold is made of lightweight metal and low-pressure molding is performed under the premise of ensuring hardness.

10. The method for preparing the low pressure forming long shroud refractory material according to claim 5, characterized in that: In the step S9, the formed green body is placed in a natural environment for 24 hours to wait for solidification.

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