Preparation method of converter slag-stopping sliding plate brick and product

Abstract

The invention discloses a preparation method of a converter slag-stopping sliding plate brick and a product, and belongs to the technical field of refractory materials. The concrete is mainly prepared from the following raw materials in percentage by weight: 60-65% of granular aggregate, 35-40% of co-grinding powder and 3-4% of an additional binding agent. The particle aggregate comprises low-carbon reclaimed material particles and electric smelting mullite particles, the particle size of the co-grinding powder is 1-0.074 mm, the co-grinding powder comprises tabular corundum powder, electric smelting mullite powder, metal silicon powder, 97 silicon carbide powder and active alpha-Al2O3 powder, and the additional binding agent is phenolic resin. The preparation method comprises the steps of co-grinding powder preparation, granular aggregate preparation, mixing, forming, drying, high-temperature firing, oil immersion, hooping, grinding, coating, veneering, inspection and packaging. The sliding plate has the advantages that the cost of the sliding plate is reduced due to the addition of the reclaimed material, the erosion resistance of the sliding plate is improved due to the mullite ceramic structure generated by high-temperature firing, the expansion coefficient of the sliding plate is reduced, the service life of the sliding plate is prolonged, and the sliding plate adapts to the converter steelmaking environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory materials, and more particularly, relates to a preparation method and product of a converter slag retaining slide brick. Background Art

[0002] With the development of the steel industry, rapid and efficient continuous casting technology has placed high performance requirements on the slide brick material, a key component in the sliding nozzle system. The slide brick material must not only withstand the chemical erosion and physical erosion of high-temperature molten steel, but also withstand severe thermal shock. Therefore, the slide brick material used in continuous casting is required to have excellent corrosion resistance, wear resistance, and thermal shock resistance. Ceramic materials have excellent corrosion resistance and wear resistance, but have poor thermal shock resistance. Mullite is a typical Al2O3·SiO2 system refractory material with great application prospects in slide brick materials.

[0003] The following are the relevant patent documents searched:

[0004] Patent Document 1: Patent Publication No. CN107382347A, published on November 24, 2017, discloses a converter slag retaining slide brick, which is prepared from the following raw materials in percentage by mass: 45% to 60% of plate-shaped corundum; 10% to 30% of zirconium mullite; 6% to 14% of alumina powder; 4% to 10% of metallic aluminum powder; 2% to 8% of silicon carbide; 1% to 3% of clay; 1% to 3% of carbon black; 0.5% to 1.5% of boron carbide; 0.5% to 1.5% of aluminum fiber; 4% to 6% of composite resin binder;

[0005] Patent Document 2: Patent publication number CN112624774A, publication date April 9, 2021, discloses a metal ceramic converter slag retaining slide brick material, the components of the slide brick material and the mass fraction of each component are: 5-15wt% mullite fiber, 60-80wt% mullite powder, 2-8wt% SiC powder, 2-3wt% carbon black, 5-10wt% metal Al powder, wherein the sum of the mass fractions of each component is 100wt%, and the slide brick is prepared according to the steps of powder mixing, pressure forming, drying, pressureless sintering and finishing treatment;

[0006] Patent document 3: The patent publication number is CN112876265A, and the publication date is June 1, 2021. It discloses a titanium silicon carbon metal composite converter slag stop slide brick, including fused zirconium corundum, fused zirconium mullite, sintered plate-shaped corundum and fused magnesium aluminum spinel particles, fused magnesium aluminum spinel powder, metallic silicon powder, metallic aluminum powder, α-calcined alumina powder, boron carbide, titanium silicon carbon and carbon black, silicone resin and thermosetting phenolic resin; the raw materials are mixed evenly, and the finished product is obtained after molding, drying, firing, steel hoop making, grinding, coating and other finishing processes.

[0007] However, the above-mentioned patent documents 1, 2 and 3 all use carbon black. With the development of high-quality steels such as low-carbon steel and clean steel, in order to prevent secondary contamination of molten steel, it is necessary to reduce the carbon pollution of molten steel by skateboard bricks, and require that while reducing the carbon content in the skateboard bricks, it is still required to maintain its good thermal shock resistance and high high-temperature strength. The presence of carbon is obviously not conducive to the casting of high-purity steel. Summary of the Invention

[0008] 1. Problem to be solved

[0009] In view of the problems in the prior art, the present invention provides a method for preparing converter slag retaining slide bricks to improve the service life of the converter slide bricks.

[0010] Another object of the present invention is to provide a converter slag retaining slide brick obtained by the above method.

[0011] 2. Technical solution

[0012] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0013] A first aspect of the present invention provides a method for preparing a converter slag retaining slide brick. The converter slag retaining slide brick used in the method includes a granular aggregate and a co-ground powder, and an additional binder that is 3% to 4% of the total mass of the granular aggregate and the co-ground powder. The mass percentage of the granular aggregate is 60% to 65%, the mass percentage of the co-ground powder is 35% to 40%, and the total percentage is 100%. The granular aggregate contains 50% to 55% low-carbon recycled material by mass, and the particle size of the low-carbon recycled material particles includes two types: 3 to 1 mm and 1 to 0 mm. The mass fractions of low-carbon recycled materials of various particle sizes are as follows:

[0014] 15-20 parts of low-carbon recycled materials with a particle size of 3-1 mm;

[0015] 20-25 parts of low-carbon recycled materials with a particle size of 1-0 mm;

[0016] The low-carbon recycled material particles have the following mass percentages: Al2O3 content ≥80%, TiO2 content ≤1%, Fe2O3 content ≤1%, and R2O content ≤0.3%.

[0017] According to any embodiment of the first aspect of the present invention, the composition of the granular aggregate contains 45% to 50% by mass of fused mullite particles or sintered mullite particles.

[0018] According to any embodiment of the first aspect of the present invention, the co-grinding powder consists of 10% to 15% of plate-shaped corundum powder, 5% to 10% of fused mullite powder, 5% to 10% of active α-Al2O3 micropowder, 5% to 10% of metallic silicon powder, and 3% to 5% of 97 silicon carbide powder.

[0019] The above 97 indicates that the weight fraction of the substance is 97%, but does not limit the physical properties of the substance. For example, the weight fraction of the substance can be 20% to 100%, or even a substance with a weight fraction of 10% can be used.

[0020] According to any embodiment of the first aspect of the present invention, the binder includes one or more of a phenolic resin and a silicone resin; wherein: the viscosity of the phenolic resin (25°C) is 12000-15000 cP, the solid content (200°C*2h) is ≥80%, and the residual carbon content (800°C*7min) is ≥45%; and the phenolic resin is a phenol formaldehyde polymer.

[0021] According to any embodiment of the first aspect of the present invention, the particle size of the fused mullite is 5-3 mm, 3-1 mm, 1-0 mm and 200 mesh, wherein the mass fractions of the fused mullite of various particle sizes are:

[0022] 15-20 parts of fused mullite with a particle size of 5-3 mm;

[0023] 5-10 parts of fused mullite with a particle size of 3-1 mm;

[0024] 5-10 parts of fused mullite with a particle size of 1-0 mm;

[0025] 5-10 parts of fused mullite with a particle size of 200 mesh;

[0026] In the fused mullite particles and fused mullite powder, the content of Al2O3 is 70%≤77%, the content of SiO2 is 22%≤29%, the content of TiO2 is 1%, the content of Fe2O3 is 0.5%, the content of R2O is 0.2%, and the mullite phase is 90%.

[0027] According to any embodiment of the first aspect of the present invention, the particle size of the plate-shaped corundum powder is 0 to 0.075 mm, and the plate-shaped corundum powder contains: Al2O3 content ≥ 99.2%, SiO2 content ≤ 0.1%, Fe2O3 content ≤ 0.1%, and R2O content ≤ 0.4%.

[0028] According to any embodiment of the first aspect of the present invention, the particle size of the metallic silicon powder is 0 to 0.075 mm, and in the metallic silicon powder: the Si content is ≥98%, the Fe content is ≤0.95%, the Al content is ≤0.6%, the Ca content is ≤0.35%, and the FC content is ≤3%.

[0029] According to any embodiment of the first aspect of the present invention, the particle size of the 97 silicon carbide powder is 0 to 0.023 mm, and in the 97 silicon carbide powder: the SiC content is ≥97%, the Fe2O3 content is ≤0.4%, the free C content is ≤3%, the SiO2 content is ≤0.6%, and the free Si is ≤0.6%.

[0030] According to any embodiment of the first aspect of the present invention, the particle size of the active α-Al2O3 micropowder is 0.002mm~0.003mm, and in the active α-Al2O3 micropowder: the Al2O3 content is ≥99.5%, the SiO2 content is ≤0.1%, the Fe2O3 content is ≤0.8%, the R2O content is ≤0.2%, and the α-Al2O3 content is correspondingly ≥93%.

[0031] The second aspect of the present invention provides a converter slag retaining slide block brick obtained by the preparation method of the converter slag retaining slide block provided by the first aspect of the present invention, wherein the carbon content is 1.63%-1-2.35%.

[0032] 3. Beneficial effects

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The converter slide brick of the present invention adopts plate-shaped corundum, metallic silicon powder, and active α-Al2O3 powder to sinter under high temperature conditions to form a mullite ceramic structure. The mullite ceramic structure has the characteristics of high melting point, creep resistance, low expansion coefficient, thermal shock resistance and excellent corrosion resistance, which increases the corrosion resistance of the converter slide brick and improves the strength of the converter slide brick, thereby improving the service life of the converter slide brick;

[0035] (2) The converter slide bricks of the present invention introduce low-carbon recycled materials, which not only recycles waste and purifies the environment, but also reduces the overall cost of converter slide bricks. In order to ensure the high-temperature performance of the slide bricks, mullite is introduced to improve the performance of the slide bricks by utilizing its excellent corrosion resistance and thermal shock resistance.

[0036] (3) The low-carbon recycled granular material in the converter slide brick material of the present invention has undergone a decarbonization treatment at 1000°C (the carbon content after treatment is 1.51%-1-1.99%). On the one hand, it greatly reduces the carbon content of the converter slide brick and reduces the carbon content introduced into the molten steel during the steel pouring process, so that it meets the needs of the steel plant for producing low-carbon steel and ultra-clean steel; on the other hand, the use of low-carbon recycled materials reduces the production cost of the converter slide brick while ensuring the use effect of the converter slide brick. DETAILED DESCRIPTION

[0037] The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but is merely for the purpose of illustrating and not limiting the features and characteristics of the present invention, so as to set forth the best mode for carrying out the invention and to enable those skilled in the art to practice the invention. Accordingly, the scope of the present invention is limited only by the appended claims.

[0038] Unless otherwise specified, all substances in the present invention are described in terms of mass percentage.

[0039] The present invention provides a method for preparing a converter slag retaining slide brick. The converter slag retaining slide brick used in the method comprises a granular aggregate and a co-ground powder, and an additional binder that accounts for 3% to 4% of the total mass of the granular aggregate and the co-ground powder. The mass percentage of the granular aggregate is 60% to 65%, the mass percentage of the co-ground powder is 35% to 40%, and the total percentage is 100%. The granular aggregate contains 50% to 55% of low-carbon recycled material by mass, and the particle size of the low-carbon recycled material particles includes two types: 3 to 1 mm and 1 to 0 mm. The mass fractions of the low-carbon recycled materials of various particle sizes are as follows:

[0040] 15-20 parts of low-carbon recycled materials with a particle size of 3-1 mm;

[0041] 20-25 parts of low-carbon recycled materials with a particle size of 1-0 mm;

[0042] The low-carbon recycled material particles have the following mass percentages: Al2O3 content ≥80%, TiO2 content ≤1%, Fe2O3 content ≤1%, and R2O content ≤0.3%.

[0043] The products obtained by the present invention are tested: (1) Erosion resistance: Industrial practice shows that mullite resists slag penetration and the plate-shaped corundum skeleton blocks erosion, extending the service life by 30-50%; (2) Strength: Micropowder filling densification + mullite grain boundary strengthening improves the room temperature / high temperature flexural strength, with a typical value of >20MPa@1400°C; (3) Service life: Comprehensive advantages of thermal shock resistance, creep resistance, and corrosion resistance reduce the replacement frequency and improve the converter operation rate.

[0044] In addition, the synergistic effect with low-carbon recycled materials: Al2O3 (≥80%) in the recycled materials serves as the aluminum source for mullite synthesis, reacting with metallic silicon powder to strengthen the ceramic structure; ultra-low impurities (Fe2O3 / TiO2 / R2O≤1%) avoid the formation of low-melting-point phases (such as iron titanate) to ensure the purity of mullite.

[0045] Example 1

[0046] The method for preparing the converter slag retaining slide brick of this embodiment 1 comprises the following steps:

[0047] Step 1: Preparation of co-ground powder: plate-shaped corundum powder, fused mullite powder, metallic silicon powder, 97 silicon carbide powder, and active α-Al2O3 powder are mixed uniformly according to the mass ratio to prepare co-ground powder;

[0048] Step 2: Preparation of granular aggregate: low-carbon recycled material particles with particle sizes of 3-1 mm and 1-0 mm and fused mullite particles with particle sizes of 5-3 mm, 3-1 mm, and 1-0 mm are uniformly mixed according to mass proportions to obtain granular aggregate;

[0049] Step 3: Mixing: Dry-mix the granular aggregate using a mixer for 3 minutes, then slowly add the phenolic resin binder and wet-mix for 8 minutes, and finally add the co-ground powder and mix for 35 minutes to obtain a mixture; wherein the mass of the phenolic resin is 4% of the total mass of the granular aggregate and the co-ground powder;

[0050] Step 4: Molding: Press the mixture into shape on a 1200t electric screw brick press to obtain bricks, and let them cool naturally for 8 hours;

[0051] Step 5: Drying: Place the bricks in a drying kiln for drying. The initial temperature of the kiln is 60°C and dry at this temperature for at least 2 hours; increase the temperature to 120°C and dry at this temperature for at least 2 hours; increase the temperature to 150°C and dry at this temperature for at least 4 hours; increase the temperature to 180°C and dry at this temperature for at least 4 hours; increase the temperature to between 200 and 230°C and dry at least 15 hours; the total drying time is at least 27 hours; select qualified semi-finished products after leaving the kiln;

[0052] Step 6: High temperature treatment: In a tunnel kiln, a high temperature treatment is carried out at a firing temperature of 1300°C under carbon buried conditions; the temperature curve is: 0-600°C heating time is 10h, 600-1000°C heating time is 20h, 1000-1300°C heating time is 20h, 1300°C (±20°C) holding time is 10h, and cooling time is 80-90h;

[0053] Step 7: Oil immersion: Place the slide bricks in a preheating kiln at 250℃ for 4 hours, then drop them into the oil immersion tank within 6 to 9 minutes to evacuate the tank. The vacuum degree should reach -0.4Mpa, and the evacuation time is 30 to 50 minutes. Then, pressurize the tank after adding asphalt to 1.3MPa and maintain the pressure for 4 hours. Then release the pressure and clean the slag.

[0054] Step 8: Make the hoop; the hoop is located in the middle, the hoop weld should not exceed 1mm, and the gap between the hoop and the slide should not exceed 1mm;

[0055] Step nine: grinding; grinding on a CNC vertical spindle rotary table surface grinder, the flatness of the skateboard working surface is less than 0.05mm, and the moisture generated during the skateboard grinding process is dried using an infrared dryer.

[0056] Example 2

[0057] The converter slag retaining slide bricks of this embodiment have the same composition and weight percentage as shown in Table 1, and are prepared in the same manner as in Example 1.

[0058] Example 3

[0059] The converter slag retaining slide bricks of this embodiment have the same composition and weight percentage as shown in Table 1, and are prepared in the same manner as in Example 1.

[0060] The components and weight percentages of the converter slag retaining slide bricks of Examples 1-3 are shown in Tables 1 and 2.

[0061] Raw material name Example 1 Example 2 Example 3 Low carbon recycled material particles / % 52 55 50 Fused mullite particles / % 13 7 10 Co-grinding / % 35 38 40 Binder / % 3.2 3.5 3.9

[0062]

[0063]

[0064] The above embodiment is used to prepare converter slag retaining slide bricks.

[0065] Table 3 compares the physical and chemical properties and average service life parameters of the converter slag retaining slide bricks obtained in Examples 1-3 above and the existing magnesia-carbon slide bricks:

[0066]

[0067] As can be seen from Table 2, the converter slag retaining slide brick of the present invention was used on a large converter. After the use, the converter slag retaining slide brick and the existing aluminum-carbon converter slide brick products were analyzed for erosion, roughening, cracking and other board conditions. The service life was 13 to 15 times, and the average diameter expansion of the casting hole was 15.7 mm, which is comparable to the erosion efficiency of the existing aluminum-zirconium-carbon converter slide. During the use of the converter slag retaining slide brick of the present invention, the crack condition of the lower slide was good, only radial fine cracks in the casting hole existed, and no abnormal erosion of the casting hole and abnormal roughening of the board surface occurred. Therefore, the converter slag retaining slide brick has excellent erosion resistance and thermal shock resistance.

[0068] Comparative Example 1

[0069] The components and weight percentages of the converter slag retaining slide bricks in this comparative example are in accordance with the formula shown in Table 1, Example 1, and the preparation method is the same as Example 1, except that the other recycled materials have a carbon content of 2.23%.

[0070] Comparative Example 2

[0071] The components and weight percentages of the converter slag retaining slide bricks in this comparative example are in accordance with the formula shown in Table 1, and the preparation method is the same as that of Example 1, except that the other recycled materials have a carbon content of 2.01%.

[0072] Comparative Example 3

[0073] The components and weight percentages of the converter slag retaining slide bricks in this comparative example are in accordance with the formula shown in Table 1, and the preparation method is the same as that of Example 1, except that the other recycled materials have a carbon content of 2.31%.

[0074] Table 4 shows the physical and chemical properties and average service life parameters of the converter slag retaining slide bricks obtained in the above comparative examples 1-3:

[0075]

[0076] The above description is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to the above description. A person skilled in the art of the present invention can make several simple deductions or substitutions without departing from the concept of the present invention, and all of them should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a converter slag retaining slide brick, wherein the converter slag retaining slide brick used in the method comprises granular aggregate and co-ground powder, and a binder which is 3% to 4% of the total mass of the granular aggregate and the co-ground powder, wherein the mass percentage of the granular aggregate is 60% to 65%, the mass percentage of the co-ground powder is 35% to 40%, and the total percentage is 100%; characterized in that: The granular aggregate contains 50% to 55% low-carbon recycled materials by mass percentage. The particle sizes of the low-carbon recycled materials include 3 to 1 mm and 1 to 0 mm. The mass fractions of the low-carbon recycled materials of various particle sizes are as follows: 15-20 parts of low-carbon recycled materials with a particle size of 3-1 mm; 20-25 parts of low-carbon recycled materials with a particle size of 1-0 mm; The low-carbon recycled material particles have the following mass percentages: Al2O3 content ≥80%, TiO2 content ≤1%, Fe2O3 content ≤1%, and R2O content ≤0.3%.

2. The method for preparing the converter slag retaining slide brick according to claim 1, characterized in that: The granular aggregate comprises 45% to 50% by mass of fused mullite particles or sintered mullite particles.

3. The method for preparing the converter slag retaining slide brick according to claim 2, characterized in that: The co-grinding powder consists of 10% to 15% of plate-shaped corundum powder, 5% to 10% of fused mullite powder, 5% to 10% of active α-Al2O3 micropowder, 5% to 10% of metallic silicon powder and 3% to 5% of 97 silicon carbide powder.

4. The method for preparing the converter slag retaining slide brick according to claim 1 or 2, characterized in that: The binder includes one or more of phenolic resin and silicone resin; wherein: the viscosity of the phenolic resin (25°C) is 12000-15000 cP, the solid content (200°C*2h) is ≥80%, and the residual carbon content (800°C*7min) is ≥45%.

5. The method for preparing the converter slag retaining slide brick according to claim 4, characterized in that: The particle sizes of the fused mullite are 5-3 mm, 3-1 mm, 1-0 mm and 200 mesh, wherein the mass fractions of the fused mullite of various particle sizes are: 15-20 parts of fused mullite with a particle size of 5-3 mm; 5-10 parts of fused mullite with a particle size of 3-1 mm; 5-10 parts of fused mullite with a particle size of 1-0 mm; 5-10 parts of fused mullite with a particle size of 200 mesh; In the fused mullite particles and fused mullite powder, the content of Al2O3 is 70%≤77%, the content of SiO2 is 22%≤29%, the content of TiO2 is 1%, the content of Fe2O3 is 0.5%, the content of R2O is 0.2%, and the mullite phase is 90%.

6. The method for preparing the converter slag retaining slide brick according to claim 5, characterized in that: The particle size of the plate-shaped corundum powder is 0-0.075 mm. In the plate-shaped corundum powder, the content of Al2O3 is ≥99.2%, the content of SiO2 is ≤0.1%, the content of Fe2O3 is ≤0.1%, and the content of R2O is ≤0.4%.

7. The method for preparing the converter slag retaining slide brick according to claim 6, characterized in that: The particle size of the metal silicon powder is 0-0.075 mm. In the metal silicon powder, the content of Si is ≥98%, the content of Fe is ≤0.95%, the content of Al is ≤0.6%, the content of Ca is ≤0.35%, and the content of FC is ≤3%.

8. The method for preparing the converter slag retaining slide brick according to claim 5, characterized in that: The particle size of the 97 silicon carbide powder is 0-0.023 mm. In the 97 silicon carbide powder, the content of SiC is ≥97%, the content of Fe2O3 is ≤0.4%, the content of free C is ≤3%, the content of SiO2 is ≤0.6%, and the free Si is ≤0.6%.

9. The method for preparing the converter slag retaining slide brick according to claim 5, characterized in that: The particle size of the active α-Al2O3 micropowder is 0.002mm-0.003mm. In the active α-Al2O3 micropowder, the content of Al2O3 is ≥99.5%, the content of SiO2 is ≤0.1%, the content of Fe2O3 is ≤0.8%, the content of R2O is ≤0.2%, and the corresponding content of α-Al2O3 is ≥93%.

10. A converter slag retaining slide brick obtained by the method for preparing the converter slag retaining slide brick according to claim 1, characterized in that: The carbon content is 1.63%-1-2.35%.

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