Thermal shock resistant magnesia carbon brick for steelmaking converter and preparation method of thermal shock resistant magnesia carbon brick

Abstract

The invention discloses a thermal shock resistant magnesia carbon brick for a steelmaking converter and a preparation method of the thermal shock resistant magnesia carbon brick, relates to the technical field of refractory materials, and aims to solve the problem that the overall service life of a furnace lining of the steelmaking converter is unbalanced due to the short service life of the magnesia carbon brick in a thermal shock concentrated area. The refractory material is prepared from the following raw materials in percentage by weight: 15 to 30 weight percent of high-purity magnesite clinker, 20 to 40 weight percent of high-purity magnesite clinker, 20 to 25 weight percent of high-purity magnesite clinker, 10 to 20 weight percent of fused magnesite, 8 to 16 weight percent of graphite, 0.5 to 1.5 weight percent of zirconium oxide powder, 1 to 3 weight percent of alpha alumina powder, 1 to 4 weight percent of antioxidant and 3 to 6 weight percent of phenolic resin. The magnesium carbon brick microstructure is constructed, the toughness mechanism is improved, the thermal shock resistance of the product is improved, and the service life of the converter lining tends to be balanced.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesia-carbon bricks, and specifically to a heat shock-resistant magnesia-carbon brick for steelmaking converters and a preparation method thereof. Background Art

[0002] As a key material for the inner linings of high-temperature equipment such as steelmaking converters and electric furnaces, magnesia-carbon bricks have long faced the challenge of insufficient heat shock resistance. During the smelting process of steelmaking converters, the charging side and trunnion parts of the converter are frequently subjected to high-temperature molten steel scouring, slag erosion, and mechanical cutting impact, which require extremely high heat shock resistance of magnesia-carbon bricks. Local damage can easily lead to imbalance in the furnace lining life. Traditional magnesia-carbon bricks mostly use fused magnesia and graphite as the main raw materials. Although they have excellent slag erosion resistance, fused magnesia has poor high-temperature toughness and a high thermal expansion coefficient, which is prone to crack propagation under thermal stress and is difficult to adapt to frequent thermal shock conditions.

[0003] CN112125650A discloses a magnesia-carbon brick for use near the electric furnace door and a preparation method thereof. By adding composite additives such as titanium carbonitride, metallic aluminum powder, and carbon fiber, the oxidation resistance and erosion resistance are improved. However, its raw material system still mainly uses fused magnesia and cannot effectively relieve the problem of heat stress concentration. In addition, its application scenario is limited to the electric furnace door and has not been adaptively improved for the basic slag environment and high-frequency thermal shock characteristics of the converter, resulting in a significant gap between the material properties and the actual requirements of the converter.

[0004] CN103601521A discloses a low-porosity periclase-magnesium aluminate spinel-zirconia sintered composite refractory material and its production process. Through the synergistic effect of in-situ generation of spinel and zirconia, the densification and thermal shock resistance are improved. However, this material is designed specifically for the acidic erosion environment of glass kilns. The introduction of zirconia is mainly used to reduce the sintering temperature, rather than using its phase transformation toughening mechanism to microstructurally construct the brick body. Moreover, the mechanism of spinel synthesis is to reduce the content of corundum phase in the brick body to avoid brick body expansion damage caused by Na2O erosion, which is completely different from the mechanism of action of α-aluminum oxide powder added to heat shock-resistant magnesia-carbon bricks for steelmaking converters.

[0005] CN210151147U discloses a heat shock-resistant magnesia-carbon brick for converter trunnions. By designing the brick body as a regular hexagon shape and adopting an alternating distribution of graphite layers and magnesia layers to reduce the thickness, an attempt is made to improve the tolerance to the cooling rate through physical structure optimization. Although this design reduces the apparent porosity and increases the bulk density to a certain extent, its improvement is only limited to the adjustment of the shape and layered composite structure and does not touch on the essential optimization of the raw material composition and microstructure.

[0006] It can be seen that traditional magnesia-carbon bricks mainly rely on the erosion resistance of magnesite and the thermal conductivity of graphite, lacking the microstructure design for thermal shock, resulting in uneven damage to key parts of the converter, thus reducing the service life of the converter. Therefore, it is urgent to carry out systematic innovation from dimensions such as raw material components, brick microstructure, and environmental adaptability. Summary of the Invention

[0007] To solve the above problems, that is, to solve the problems raised in the above background technology, the present invention proposes a thermal shock-resistant magnesia-carbon brick for steelmaking converters and its preparation method. According to the different characteristics and functions of raw materials, high-purity sintered magnesite and fused magnesite are graded, and combined with the phase transformation toughening of zirconia powder and the in-situ spinel reaction of α-aluminum oxide powder, the microstructure of the brick is constructed, achieving a significant improvement in the thermal shock resistance of the magnesia-carbon brick. It is made from the following raw materials in parts by weight: 15-30 wt% of high-purity sintered magnesite with a particle size range of 3 mm - 5 mm, 20-40 wt% of high-purity sintered magnesite with a particle size range of 1 mm - 3 mm, 20-25 wt% of high-purity sintered magnesite with a particle size range of 0 mm - 1 mm, 10-20 wt% of fused magnesite with a particle size ≤ 0.088 mm, 8-16 wt% of graphite, 0.5-1.5 wt% of zirconia powder with a particle size ≤ 0.044 mm, 1-3 wt% of α-aluminum oxide powder with a particle size ≤ 0.044 mm, 1-4 wt% of antioxidant with a particle size ≤ 0.088 mm, and 3-6 wt% of phenolic resin.

[0008] The further setting of the present invention is that the content of magnesium oxide in the high-purity sintered magnesite ≥ 98.5 wt%, the particle bulk density ≥ 3.42 g / cm 3 , and the molar ratio of calcium oxide to silicon dioxide ≥ 3.

[0009] The further setting of the present invention is that the content of magnesium oxide in the fused magnesite ≥ 97.5 wt%, the particle bulk density ≥ 3.45 g / cm 3 , and the molar ratio of calcium oxide to silicon dioxide ≥ 3.

[0010] The further setting of the present invention is that the carbon content in the graphite ≥ 96 wt%.

[0011] The further setting of the present invention is that the zirconia powder contains ≥ 98 wt% of zirconia.

[0012] The further setting of the present invention is that the alumina powder contains ≥ 99 wt% of alumina.

[0013] The further setting of the present invention is that the antioxidant includes, but is not limited to, one or more of aluminum powder, magnesium-aluminum alloy powder, and aluminum nitride powder.

[0014] The further settings of the present invention are as follows: including the following steps: S1. Crush high-purity sintered magnesite into particles with particle size ranges of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and finely grind fused magnesite into fine powder with a particle size ≤ 0.088 mm after crushing; S2. Premix fused magnesite powder, α-aluminum oxide powder, zirconia powder, and antioxidant according to the ratio to obtain premixed powder for standby; S3. Dry mix the three particle size graded high-purity sintered magnesite described in S1 for 1 - 3 min, add phenolic resin binder, knead for 3 - 5 min, add graphite, knead for 5 - 15 min, and finally add the premixed powder and knead for 15 - 20 min. After good kneading, press into brick blanks; S4. Send the brick blanks into a drying kiln at 200 - 300 °C for heat treatment for more than 6 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters.

[0015] The beneficial technical effects of the present invention are as follows: The present invention mainly constructs the microstructure of the magnesia-carbon brick and improves its toughening mechanism to achieve the purpose of improving the thermal shock resistance. The gradient grading of high-purity sintered magnesite and fused magnesite forms a dual-effect synergistic mechanism of toughness and corrosion resistance. Among them, the high-purity sintered magnesite particle size material replaces part of the fused magnesite particle size material. With the characteristics of clean grain boundaries and excellent high-temperature toughness, the high-purity sintered magnesite effectively inhibits the propagation of thermal shock cracks; the fine powder of fused magnesite ensures the slag erosion resistance through high density. The combination of the two enables the material to have both durability and stability under extreme thermal and mechanical coupling conditions, and enhances the thermal shock resistance of the product while ensuring the corrosion resistance.

[0016] α-aluminum oxide powder reacts in situ with magnesia at high temperature to generate magnesium aluminate spinel. Its high bonding strength significantly improves the high-temperature stability of the matrix. At the same time, due to the difference in thermal expansion coefficients between the spinel and the matrix, uniformly distributed expansion microcracks are formed, which can effectively absorb and disperse thermal stress.

[0017] Zirconia powder induces the generation of a microcrack network through the phase transformation effect between the monoclinic phase and the tetragonal phase, further dispersing stress concentration, forming a "macro-meso-micro" multi-level toughening barrier, and the thermal shock resistance is greatly improved compared with traditional magnesia-carbon bricks.

[0018] During high-temperature use, zirconia powder can also form a limited solid solution with α-aluminum oxide powder, playing an effect of improving the toughening of the brick matrix, thereby improving the impact resistance of the magnesia-carbon brick.

[0019] Aiming at the basic slag environment of the converter, by controlling the spinel stoichiometric ratio and the stabilization treatment of zirconia powder, the chemical stability of the material under alkaline conditions is ensured. At the same time, the synergistic effect of the phenolic resin binder and the antioxidant effectively inhibits the oxidation of graphite, reduces structural looseness, the apparent porosity is controlled at 2.0% - 3.5%, and the bulk density reaches 2.96 - 3.07 g / cm³.

[0020] Optimize the kneading and heat treatment processes to ensure the uniform dispersion of raw materials and the denseness of the microstructure. The high-temperature flexural strength reaches 8.1 - 11.7 MPa, and the compressive strength is 46 - 56 MPa, significantly reducing the spalling risk at parts such as the charging side and trunnion of the converter. Description of the Drawings

[0021] Figure 1 Shows a schematic diagram of a 50-fold magnification of the scanning electron microscope of the magnesia-carbon brick prepared in Example 3 of the present invention.

[0022] Figure 2 Shows a schematic diagram of a 100-fold magnification of the scanning electron microscope of the magnesia-carbon brick prepared in Example 3 of the present invention.

[0023] Figure 3 Shows a schematic diagram of a 400-fold magnification of the scanning electron microscope of the magnesia-carbon brick prepared in Example 3 of the present invention. Detailed Description of the Invention

[0024] The following refers to the attached Figures 1 - 3 to describe the preferred embodiments of the present invention. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention and are not intended to limit the protection scope of the present invention.

[0025] Phenolic resin is an externally added binder and is not included in the total mass of the raw materials. Examples

[0026] S1. Crush high-purity sintered magnesia into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and finely grind the fused magnesia into fine powder with a particle size ≤ 0.088 mm after crushing; S2. Select 10 wt% of fused magnesia with a particle size ≤ 0.088 mm, 3 wt% of α-aluminum oxide powder with a particle size ≤ 0.044 mm, 1 wt% of zirconia powder with a particle size ≤ 0.044 mm, and 4 wt% of aluminum powder with a particle size ≤ 0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 15 wt% of high-purity sintered magnesia with a particle size of 3 mm - 5 mm, 30 wt% of high-purity sintered magnesia with a particle size of 1 mm - 3 mm, and 25 wt% of high-purity sintered magnesia with a particle size of 0 mm - 1 mm, dry mix for 3 min, then add 3 wt% of phenolic resin binder, knead for 4 min, add 12 wt% of graphite, knead for 5 min, and finally add the premixed powder and knead for 20 min. After kneading well, press into brick blanks; S4. Send the brick blanks into a drying kiln at 220 °C for heat treatment for 6 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters. Examples

[0027] S1. Crush high-purity sintered magnesia into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm. After crushing fused magnesia, finely grind it into a fine powder with a particle size ≤ 0.088 mm; S2. Select 10 wt% of fused magnesia with a particle size ≤ 0.088 mm, 3 wt% of α-aluminum oxide powder with a particle size ≤ 0.044 mm, 1 wt% of zirconia powder with a particle size ≤ 0.044 mm, 1.5 wt% of aluminum powder with a particle size ≤ 0.088 mm, and 1 wt% of aluminum nitride with a particle size ≤ 0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 22.5 wt% of high-purity sintered magnesia with a particle size of 3 mm - 5 mm, 20 wt% of high-purity sintered magnesia with a particle size of 1 mm - 3 mm, and 25 wt% of high-purity sintered magnesia with a particle size of 0 mm - 1 mm. After dry mixing for 2 min, add 4.5 wt% of phenolic resin binder, knead for 4 min, add 16 wt% of graphite, knead for 10 min, and finally add the premixed powder and knead for 15 min. After kneading well, press it into a brick blank; S4. Send the brick blank into a drying kiln at 230 °C for heat treatment for 6.5 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters. Example

[0028] S1. Crush high-purity sintered magnesia into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm. After crushing fused magnesia, finely grind it into a fine powder with a particle size ≤ 0.088 mm; S2. Select 15 wt% of fused magnesia with a particle size ≤ 0.088 mm, 1 wt% of α-aluminum oxide powder with a particle size ≤ 0.044 mm, 0.5 wt% of zirconia powder with a particle size ≤ 0.044 mm, and 1 wt% of magnesium-aluminum alloy powder with a particle size ≤ 0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 30 wt% of high-purity sintered magnesia with a particle size of 3 mm - 5 mm, 20 wt% of high-purity sintered magnesia with a particle size of 1 mm - 3 mm, and 22.5 wt% of high-purity sintered magnesia with a particle size of 0 mm - 1 mm. After dry mixing for 2 min, add 6 wt% of phenolic resin binder, knead for 4 min, add 10 wt% of graphite, knead for 10 min, and finally add the premixed powder and knead for 15 min. After kneading well, press it into a brick blank; S4. Send the brick blank into a drying kiln at 230 °C for heat treatment for 7 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters. Example

[0029] S1. Crush high-purity sintered magnesia into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm. After crushing fused magnesia, finely grind it into a fine powder with a particle size ≤ 0.088 mm; S2. Select 10 wt% of fused magnesia with a particle size ≤ 0.088 mm, 2 wt% of α-aluminum oxide powder with a particle size ≤ 0.044 mm, 1 wt% of zirconia powder with a particle size ≤ 0.044 mm, 2 wt% of magnesium-aluminum alloy powder with a particle size ≤ 0.088 mm, and 2 wt% of aluminum nitride powder with a particle size ≤ 0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 15 wt% of high-purity sintered magnesia with a particle size of 3 mm - 5 mm, 40 wt% of high-purity sintered magnesia with a particle size of 1 mm - 3 mm, and 20 wt% of high-purity sintered magnesia with a particle size of 0 mm - 1 mm, dry mix for 2 min, then add 3 wt% of phenolic resin binder, knead for 4 min, add 8 wt% of graphite, knead for 10 min, and finally add the premixed powder and knead for 15 min. After kneading well, press into a brick blank; S4. Send the brick blank into a drying kiln at 230 °C for heat treatment for 7 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters. Example

[0030] S1. Crush high-purity sintered magnesia into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and after crushing the fused magnesia, finely grind it into a fine powder with a particle size ≤ 0.088 mm; S2. Select 20 wt% of fused magnesia with a particle size ≤ 0.088 mm, 2 wt% of α-aluminum oxide powder with a particle size ≤ 0.044 mm, 1.5 wt% of zirconia powder with a particle size ≤ 0.044 mm, and 1 wt% of magnesium-aluminum alloy powder with a particle size ≤ 0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 22.5 wt% of high-purity sintered magnesia with a particle size of 3 mm - 5 mm, 20 wt% of high-purity sintered magnesia with a particle size of 1 mm - 3 mm, and 25 wt% of high-purity sintered magnesia with a particle size of 0 mm - 1 mm, dry mix for 2 min, then add 4.5 wt% of phenolic resin binder, knead for 4 min, add 8 wt% of graphite, knead for 10 min, and finally add the premixed powder and knead for 15 min. After kneading well, press into a brick blank; S4. Send the brick blank into a drying kiln at 230 °C for heat treatment for 7 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters.

[0031] S1. Crush ordinary fused magnesia with a MgO content ≥ 96.5% into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and after crushing the fused magnesia, finely grind it into a fine powder with a particle size ≤ 0.088 mm; S2. Select 14 wt% of fused magnesia with a particle size ≤ 0.088 mm and 1 wt% of aluminum powder with a particle size ≤ 0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 30 wt% of fused magnesia with a particle size of 3 mm - 5 mm, 20 wt% of fused magnesia with a particle size of 1 mm - 3 mm, and 25 wt% of fused magnesia with a particle size of 0 mm - 1 mm, dry mix them for 3 min, then add 3 wt% of phenolic resin binder, knead for 4 min, add 10 wt% of graphite, knead for 5 min, and finally add the premixed powder and knead for 20 min. After kneading well, press them into brick blanks; S4. Send the brick blanks into a drying kiln at 220 °C for heat treatment for 6 h to obtain magnesia - carbon bricks for steel - making converters.

[0032] S1. Crush fused magnesia with a common MgO content of ≥96.5% into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and after crushing, finely grind the fused magnesia into fine powder with a particle size ≤0.088 mm; S2. Select 15 wt% of fused magnesia with a particle size ≤0.088 mm and 3 wt% of aluminum powder with a particle size ≤0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 20 wt% of fused magnesia with a particle size of 3 mm - 5 mm, 30 wt% of fused magnesia with a particle size of 1 mm - 3 mm, and 20 wt% of fused magnesia with a particle size of 0 mm - 1 mm, dry mix them for 3 min, then add 3 wt% of phenolic resin binder, knead for 4 min, add 12 wt% of graphite, knead for 5 min, and finally add the premixed powder and knead for 20 min. After kneading well, press them into brick blanks; S4. Send the brick blanks into a drying kiln at 220 °C for heat treatment for 6 h to obtain magnesia - carbon bricks for steel - making converters.

[0033] S1. Crush fused magnesia with a common MgO content of ≥96.5% into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and after crushing, finely grind the fused magnesia into fine powder with a particle size ≤0.088 mm; S2. Select 12 wt% of fused magnesia with a particle size ≤0.088 mm and 2 wt% of aluminum powder with a particle size ≤0.088 mm for premixing to obtain a premixed powder for standby; S3. Select 25 wt% of fused magnesia with a particle size of 3 mm - 5 mm, 20 wt% of fused magnesia with a particle size of 1 mm - 3 mm, and 25 wt% of fused magnesia with a particle size of 0 mm - 1 mm, dry mix them for 3 min, then add 3 wt% of phenolic resin binder, knead for 4 min, add 16 wt% of graphite, knead for 5 min, and finally add the premixed powder and knead for 20 min. After kneading well, press them into brick blanks; S4. Send the brick blanks into a drying kiln at 210 °C for heat treatment for 6 h to obtain magnesia - carbon bricks for steel - making converters.

[0034] Table 1 Physical and Chemical Properties of the Product Item Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 MgO, wt% 79.3 76.2 86.5 84.7 86.2 81.3 77.3 73.2 C, wt% 12.5 16.2 10.5 8.3 8.8 10.2 12.3 16.1 Cold Crushing Strength, MPa 49 46 57 54 56 45 41 39 Apparent Porosity, % 2.2 2 2.8 3.2 3.5 4.2 3.6 2.9 <![CDATA[Bulk density, g / cm 3 > 3.02 2.96 3.03 3.06 3.07 2.99 2.95 2.91 Hot Modulus of Rupture at 1400°C for 0.5 h, MPa 10.5 11.7 9.8 8.4 8.1 6.8 7.7 8.6 In Examples 1-5, high-purity sintered magnesite grits with good high-temperature toughness, high purity, and high density were selected to replace the fused magnesite grits, which not only maintained good erosion resistance but also effectively enhanced the thermal shock resistance of the products. The added α-aluminum oxide powder reacted with magnesia at high temperatures to form magnesium aluminate spinel, which not only strengthened the high-temperature bonding strength of the matrix but also effectively buffered the thermal shock stress by generating expansion microcracks. At the same time, the zirconia powder induced microcracks through phase transformation and played a toughening role, further improving the thermal shock resistance and optimizing the overall performance of the brick.

[0035] Example 3 fine-tuned the raw material dosage and ratio on the basis of Examples 1 and 2, further optimized the microstructure, greatly improved the thermal shock resistance, and the comprehensive properties such as the compressive strength and high-temperature stability of the products were also more excellent, better coping with thermal shock and other situations under complex working conditions.

[0036] Examples 4 and 5, through precise proportioning and control of each raw material, gave full play to the synergistic effect of high-purity sintered magnesite grits, α-aluminum oxide powder, and zirconia powder, had unique advantages in strengthening the thermal shock resistance, improved the toughening mechanism of the brick from multiple aspects, effectively buffered the thermal shock stress, ensured that the magnesia-carbon brick could stably exhibit good performance in actual applications, and laid a foundation for its long-term use in key application scenarios such as converters and electric furnaces. The five examples jointly verified the effectiveness and feasibility of the present invention in improving the performance of magnesia-carbon bricks from different angles.

[0037] Comparative Examples 1-3 used the traditional magnesia-carbon brick formula, with ordinary fused magnesite as the main raw material, relying only on aluminum powder for antioxidant protection. Although the basic erosion resistance was retained, due to the single raw material and unoptimized microstructure, the apparent porosity was relatively high, the compressive strength was relatively low, and the high-temperature flexural strength was only 6.8-8.6 MPa. The problem of thermal stress concentration remained unsolved, and the maintenance frequency of the key parts of the converter was still limited to 600-1000 furnaces, revealing the inherent defects of traditional materials in thermal shock resistance and structural stability. In contrast, the present invention systematically optimized the microstructure and toughening mechanism through the synergistic effect of gradient grading of high-purity sintered magnesite, zirconia phase transformation toughening, and α-aluminum oxide spinel reaction, thus achieving performance breakthroughs that could not be achieved by the comparative examples.

[0038] It can be seen that through the refined control of different raw material ratios and process parameters, the five embodiments always revolve around the core goal of optimizing the microstructure and toughening mechanism, and multi-dimensionally improve the thermal shock resistance of magnesia-carbon bricks. The maintenance frequency of the magnesia-carbon bricks prepared by the present invention at the charging side and trunnion of the converter and other parts has been significantly extended from 600 - 1000 furnaces to more than 1200 furnaces, not only balancing the ladle life, but also raising the overall service life of the converter to a new height. It not only solves the problem of local damage caused by thermal stress concentration of traditional materials, but also fills the gap of insufficient adaptability of magnesia-carbon bricks for refractory materials under complex working conditions with high density, high strength and excellent thermal stability.

[0039] Table 2 Raw material purchasing manufacturers Raw Material Manufacturer High - purity Sintered Magnesia Jiachen Group Zirconia Powder Imerys Fused Minerals (Yingkou) Co., Ltd. α - Alumina Powder Kaifeng Gaoda Furnace Charge Co., Ltd. In view of the fact that the numerical values of the product physical and chemical performance detection items in Table 1 are all obtained by manually reading and transcribing or calculating the instrument and equipment, and the methods and detection standards for all data that need to be calculated strictly follow the National Standard of the People's Republic of China "Magnesia-carbon Bricks" (GB / T 22589-2017), which involves complex calculation and verification processes. Since this type of manual operation and standard following process cannot be completely reproduced by electronic means, an electronic detection certificate report cannot be issued.

[0040] Although the present invention has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

[0041] In the description of the present invention, the terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., which indicate directions or position relationships, are based on the directions or position relationships shown in the drawings. This is only for the convenience of description, rather than indicating or implying that the device or element must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0042] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, article, or apparatus / device comprising a series of elements includes not only those elements but also other elements not expressly listed, or also elements inherent to those process, article, or apparatus / device.

[0044] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A heat shock resistant magnesia-carbon brick for steelmaking converters, characterized in that: It is made from the following raw materials in parts by weight: 15-30 wt% of high-purity sintered magnesia with a particle size range of 3 mm - 5 mm, 20-40 wt% of high-purity sintered magnesia with a particle size range of 1 mm - 3 mm, 20-25 wt% of high-purity sintered magnesia with a particle size range of 0 mm - 1 mm, 10-20 wt% of fused magnesia with a particle size ≤ 0.088 mm, 8-16 wt% of graphite, 0.5-1.5 wt% of zirconia powder with a particle size ≤ 0.044 mm, 1-3 wt% of α-alumina powder with a particle size ≤ 0.044 mm, 1-4 wt% of antioxidant with a particle size ≤ 0.088 mm, and 3-6 wt% of phenolic resin.

2. The anti-thermal shock magnesia-carbon brick for steelmaking converter according to claim 1, characterized in that: The content of magnesium oxide in the high-purity sintered magnesia is ≥98.5 wt%, the bulk density of the particles is ≥3.42 g / cm 3 , and the molar ratio of calcium oxide to silicon dioxide is ≥3.

3. The anti-thermal shock type magnesia-carbon brick for steelmaking converter according to claim 1, characterized in that: The content of magnesium oxide in the fused magnesia is ≥97.5 wt%, and the bulk density of the particles is ≥3.45 g / cm 3 , and the molar ratio of calcium oxide to silicon dioxide is ≥3.

4. The thermal shock resistant magnesia-carbon brick for steelmaking converter according to claim 1, characterized in that: The carbon content in the graphite is ≥ 96 wt%.

5. The magnesia-carbon brick with thermal shock resistance for steelmaking converter according to claim 1, characterized in that: The zirconia content in the zirconia powder is ≥ 98 wt%.

6. The magnesia-carbon brick with thermal shock resistance for steelmaking converter according to claim 1, characterized in that: The alumina content in the α-alumina powder is ≥ 99 wt%.

7. The anti-thermal shock type magnesia-carbon brick for steelmaking converter according to claim 1, characterized in that: The antioxidant includes, but is not limited to, one or more of aluminum powder, magnesium-aluminum alloy powder, and aluminum nitride powder.

8. A preparation method of the thermal shock resistant magnesia-carbon brick for steelmaking converters according to claim 1, characterized in that: It includes the following steps: S1. Crush the high-purity sintered magnesia into particles with a particle size range of 3 mm - 5 mm, 1 mm - 3 mm, and 0 mm - 1 mm, and finely grind the fused magnesia into a fine powder with a particle size ≤ 0.088 mm after crushing. S2. Premix the fused magnesia powder, α-alumina powder, zirconia powder, and antioxidant according to the ratio to obtain a premixed powder for standby. S3. Dry mix the three particle size gradings of high-purity sintered magnesia described in S1 for 1-3 min, then add the phenolic resin binder and knead for 3-5 min, add graphite and knead for 5-15 min, and finally add the premixed powder described in S2 and knead for 15-20 min. After good kneading, press it into a brick blank. S4. Send the brick blank into a drying kiln at 200-300 °C for heat treatment for more than 6 h to obtain a thermal shock-resistant magnesia-carbon brick for steelmaking converters.

Images