Dispersion type magnesian air brick for steel ladle and preparation method of diffusion type magnesian air brick

Abstract

The invention discloses a diffuse-type magnesium air brick for a steel ladle and a preparation method of the diffuse-type magnesium air brick. The diffuse-type magnesium air brick is prepared from the following raw materials in parts by weight: 70-90 parts of magnesia particles, 5-25 parts of magnesium oxide fine powder, 0-20 parts of a performance additive and 1-8 parts of a binding agent. The diffusion type magnesian air brick is good in oxygen burning resistance and thermal shock stability, the magnesian refractory material has good erosion resistance to alkaline slag, the thermal stability and slag permeability resistance of the air brick are improved due to the addition of the performance additive, air holes of the air brick are evenly distributed in a diffusion mode, a large number of diffusion bubbles are formed, and the air brick has the good air permeability. Impurities can be promoted to float upwards, and the cleanliness of molten steel is improved.

Description

Technical Field

[0001] This invention relates to the field of refractory permeable brick technology. Specifically, it relates to dispersed magnesia permeable bricks for steel ladles and their preparation method. Background Technology

[0002] Ladle refining has become a crucial step in modern steelmaking processes. As a key functional component in ladle refining technology, the performance of permeable bricks directly impacts the quality of molten steel. With the development of refining processes in Chinese steel mills, operating conditions have become increasingly stringent, demanding higher lifespans, blowing rates, and permeability from permeable bricks.

[0003] Currently, there are many types of permeable bricks. Among them, the formation of pores inside the diffuse permeable brick mainly relies on the mutual accumulation of particles. During use, a large number of diffuse small bubbles are generated. These bubbles have a large specific surface area, making it easier to capture inclusions in molten steel and making the composition and temperature of molten steel more uniform. Therefore, they are widely used as permeable elements in steel ladles.

[0004] However, the material of the dispersion permeable bricks significantly affects the quality of molten steel during the refining process. Domestically used dispersion permeable bricks for steel ladles are mainly made of materials such as chromium corundum, chromium corundum-spinel, corundum, and corundum-spinel. During use, these bricks easily generate non-metallic inclusions of alumina in the molten steel and introduce oxygen, which is detrimental to the smelting of clean steel. Furthermore, due to the low melting point of aluminum materials, oxygen combustion during use causes significant damage, significantly affecting the service life of the permeable bricks and disrupting the steel plant's production schedule.

[0005] In addition, the high porosity of the diffused permeable brick makes the pores prone to collapse and cracking under high-temperature service conditions, which weakens the resistance to erosion and reduces the overall strength of the permeable brick, thus affecting its service life. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide a dispersed magnesia permeable brick for steel ladles that does not contaminate molten steel, has good air permeability, corrosion resistance, oxygen resistance and erosion resistance, and excellent high-temperature strength and thermal shock stability, as well as its preparation method.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] Dispersed magnesia permeable bricks for steel ladles are composed of the following raw materials in parts by weight: 70-90 parts by weight of magnesia sand particles, 5-25 parts by weight of fine magnesia powder, 0-20 parts by weight of performance additives and 1-8 parts by weight of binder.

[0009] The particle size range of magnesia is greater than 0.5 mm and less than or equal to 1 mm;

[0010] The particle size range of magnesium oxide fine powder is greater than 0.045 mm and less than or equal to 0.088 mm;

[0011] The particle size range of the performance additives is less than or equal to 0.045 mm.

[0012] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, the MgO content in the magnesia particles and the magnesia fine powder is greater than 96 wt%.

[0013] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, the performance additives are one or more of chromium oxide fine powder, magnesium aluminum spinel fine powder, and zirconium oxide fine powder; the chromium oxide fine powder is 0-20 parts by weight, the magnesium aluminum spinel fine powder is 0-20 parts by weight, and the zirconium oxide fine powder is 0-20 parts by weight.

[0014] The above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, wherein the binder is one or more of lignosulfonate, starch, phenolic resin, epoxy resin, dextrin, and pulp powder; the lignosulfonate is 1-5 parts by weight, the starch is 1-5 parts by weight, the phenolic resin is 1-5 parts by weight, the epoxy resin is 1-5 parts by weight, the dextrin is 1-5 parts by weight, and the pulp powder is 1-5 parts by weight.

[0015] The preparation method of the above-mentioned dispersed magnesia permeable brick for steel ladles includes the following steps:

[0016] (1) Prepare raw materials according to the above-mentioned formula for dispersed magnesia permeable bricks;

[0017] (2) Mix magnesia particles, fine magnesium oxide powder, binder and performance additives and knead them to obtain a uniformly mixed material;

[0018] (3) The uniformly mixed materials are pressed into brick blanks of the corresponding size by machine pressing or isostatic pressing.

[0019] (4) The blank bricks are sent into the drying hole for drying to obtain sample A. The drying temperature is 110-200℃ and the drying time is 24-72 hours.

[0020] (5) The sample A is sent into a shuttle kiln or tunnel kiln for firing at a temperature of 1600-1800℃ for 48-72 hours to obtain a dispersed magnesia permeable brick for steel ladle.

[0021] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, in step (2):

[0022] The binder includes powdered phenolic resin and liquid phenolic resin. Magnesia particles and powdered phenolic resin are added to a mixer and mixed for 1 to 3 minutes. Liquid phenolic resin is added and mixed for another 3 to 5 minutes. Then, fine magnesium oxide powder and performance additives are added and mixed for another 10 to 15 minutes to obtain a uniformly mixed material.

[0023] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, in step (2), before mixing, zirconium oxide fine powder is coated on the surface of magnesia particles: magnesia particles are added to 100-200 parts by weight of water and stirred evenly, then 3-30 parts by weight of zirconium oxychloride octahydrate ZrOCI2·8H2O is added, and stirring is continued for 15-20 minutes, and then dried at a temperature of 150-200℃ for 12-20 hours, and then heated to 500-600℃ for 12-15 hours, thereby achieving zirconium oxide coating on the surface of magnesia particles.

[0024] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, in step (2), before mixing, fine zirconium oxide powder and fine magnesium aluminum spinel powder are coated on the surface of magnesia particles: magnesia particles are added to 100-200 parts by weight of water and stirred evenly. Then, 3-30 parts by weight of zirconium oxychloride octahydrate ZrOCI2·8H2O and 2-10 parts by weight of aluminum chloride are added. Stirring is continued for 15-20 minutes, and then drying is carried out at a temperature of 150-200℃. The temperature is then raised to 500-600℃ and the holding time is 12-15 hours, thereby achieving the coating of zirconium oxide and magnesium aluminum spinel on the surface of magnesia particles.

[0025] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, chitin is mixed evenly with magnesia particles before the performance additives are coated onto the magnesia particles.

[0026] In the above-mentioned method for preparing dispersed magnesia permeable bricks for steel ladles, the amount of chitosan added is 5 to 20 parts by weight.

[0027] The technical solution of the present invention achieves the following beneficial technical effects:

[0028] 1. Excellent resistance to oxygen burning and thermal shock:

[0029] Due to its high magnesium oxide content, dispersed magnesia-permeable bricks can form high-melting-point compounds or solid solutions with many oxides or slag components, and the resulting binary system also has a high eutectic temperature. During oxygen combustion, the high melting point of magnesium oxide and its solid solution contributes to the good resistance to oxygen combustion and thermal shock stability of dispersed magnesia-permeable bricks.

[0030] 2. Excellent resistance to slag erosion:

[0031] Magnesia refractory materials have excellent resistance to erosion by alkaline slag, and the addition of performance additives improves the thermal shock stability and slag penetration resistance of permeable bricks.

[0032] 3. Excellent steel purification effect:

[0033] Dispersed magnesia-based permeable bricks are suitable for smelting high-performance steels such as clean steel, stainless steel, and special steels. The magnesium oxide and calcium oxide in the permeable bricks have low oxygen partial pressures at the dissolution equilibrium of molten steel at 1600℃, which is beneficial for desulfurization and dephosphorization of the molten steel, thus promoting the production of low-oxygen and clean steel. Furthermore, the permeable bricks of this invention have uniformly distributed pores in a dispersed pattern, forming a large number of dispersed bubbles that promote the floating of impurities and improve the cleanliness of the molten steel.

[0034] 4. Coating performance additives onto the surface of magnesium oxide particles to improve the strength of permeable bricks:

[0035] On the one hand, it is difficult to ensure uniform distribution of granular and powder materials during the mixing process; on the other hand, for dispersion permeable bricks, although higher porosity increases the air permeability, the inner walls of the dispersion permeable pores may also collapse, crack, and erode during high-temperature service, thus affecting the overall strength of the permeable bricks.

[0036] When magnesia particles are mixed with zirconium oxychloride, the zirconium oxychloride hydrolyzes in water to form zirconium oxide hydrate (ZrO2·xH2O). This hydrate is a gel with variable water content, allowing the zirconium oxide gel material to uniformly coat the surface of the magnesia particles. During high-temperature heating, the zirconium oxide reacts in situ with the calcium oxide in the magnesia to form calcium zirconate phase (CaZrO3), which greatly enhances the strength of the pore walls of the permeable brick, reduces the risk of pore wall collapse and damage, improves the erosion resistance of the pore walls, enhances the overall strength of the permeable brick, and extends its service life.

[0037] Aluminum chloride hydrolyzes to form aluminum hydroxide gel, which can uniformly coat the surface of magnesia particles. During high-temperature heating, the aluminum hydroxide gel forms Al2O3, and aluminum oxide reacts with magnesium oxide in situ to form magnesium aluminum spinel phase (chemical formula: MgAl2O4), which increases the roughness of the pore wall surface, improves the slag resistance of the pore wall, and improves the overall compressive strength of the permeable brick. At the same time, the spinel formation reaction is also accompanied by a volume expansion effect, which can further increase the porosity of the permeable brick and increase the air permeability.

[0038] In addition, in order to achieve uniform and stable coating of zirconia gel and aluminum hydroxide gel on the surface of magnesia particles, the magnesia particles are uniformly mixed with chitin before coating. Chitin exhibits negative charge in water. By stirring the mixture evenly in water, the surface of the magnesia particles is given a negative charge. Then, it is mixed with positively charged zirconia gel and aluminum hydroxide gel, which can generate a stable and uniform calcium zirconate phase and magnesium aluminum spinel phase on the surface of magnesia particles.

[0039] 5. Using only solid powdered phenolic resin requires the addition of alcohol to achieve a binding effect. However, combining solid powdered phenolic resin with liquid phenolic resin is more effective in coating the powder onto the particle surface, achieving a better granulation result. Detailed Implementation

[0040] Example 1

[0041] For steel ladle dispersion-type magnesia-based permeable bricks, the raw materials shall be weighed according to the following mass fractions:

[0042] Magnesia granules: particle size greater than 0.5 mm and less than or equal to 1 mm, 75 kg;

[0043] Magnesium oxide fine powder: particle size greater than 0.045 mm and less than or equal to 0.088 mm, 25 kg;

[0044] The binder is phenolic resin (including powdered phenolic resin and liquid phenolic resin).

[0045] Powdered phenolic resin: 0.5 kg;

[0046] Liquid phenolic resin: 5 kg;

[0047] The above-mentioned process for manufacturing magnesia-based permeable bricks for steel ladles is as follows: Magnesia granules and powdered phenolic resin are mixed in a planetary mixer for 2 minutes according to the above ratio, then liquid phenolic resin is added and mixed for 5 minutes, followed by the addition of fine magnesium oxide powder according to the above ratio and mixing for 15 minutes to obtain a uniformly mixed material. The uniformly mixed material is then isostatically pressed into brick blanks of the corresponding size, and then dried in a drying tunnel at 200℃. After 48 hours, sample A is obtained, which is then sent to a kiln for firing at 1600℃ for 72 hours to obtain the magnesia-based permeable brick. Table 1 shows the physicochemical properties of the obtained magnesia-based permeable bricks after firing.

[0048] Table 1

[0049]

[0050] Example 2

[0051] For steel ladle dispersion-type magnesia-based permeable bricks, the raw materials shall be weighed according to the following mass fractions:

[0052] Magnesia granules: particle size greater than 0.5 mm and less than or equal to 1 mm, 85 kg;

[0053] Magnesium oxide fine powder: particle size greater than 0.045 mm and less than or equal to 0.088 mm, 15 kg;

[0054] The binder is phenolic resin (including powdered phenolic resin and liquid phenolic resin).

[0055] Powdered phenolic resin: 0.5 kg;

[0056] Liquid phenolic resin: 5 kg;

[0057] The above-mentioned process for manufacturing magnesia-based permeable bricks for steel ladles is as follows: Magnesia granules and powdered phenolic resin are mixed in a planetary mixer for 2 minutes according to the above ratio, then liquid phenolic resin is added and mixed for 5 minutes, followed by the addition of fine magnesium oxide powder according to the above ratio and mixing for 15 minutes to obtain a uniformly mixed material. The uniformly mixed material is then isostatically pressed into brick blanks of the corresponding size, and then dried in a drying tunnel at 200℃. After 48 hours, sample A is obtained, which is then sent to a kiln for firing at 1650℃ for 60 hours to obtain the magnesia-based permeable brick. Table 2 shows the physicochemical properties of the obtained magnesia-based permeable bricks after firing.

[0058] Table 2

[0059]

[0060] Example 3

[0061] For steel ladle dispersion-type magnesia-based permeable bricks, the raw materials shall be weighed according to the following mass fractions:

[0062] For steel ladle dispersion-type magnesia-based permeable bricks, the raw materials shall be weighed according to the following mass fractions:

[0063] Magnesia granules: particle size greater than 0.5 mm and less than or equal to 1 mm, 80 kg;

[0064] Magnesium oxide fine powder: particle size greater than 0.045 mm and less than or equal to 0.088 mm, 17 kg;

[0065] The performance additive is fine chromium oxide powder; the binder is phenolic resin (including powdered phenolic resin and liquid phenolic resin).

[0066] Chromium oxide fine powder: particle size less than or equal to 0.045 mm, 3 kg;

[0067] Powdered phenolic resin: 0.5 kg;

[0068] Liquid phenolic resin: 5 kg;

[0069] The above-mentioned process for manufacturing magnesia-based permeable bricks for steel ladles is as follows: Magnesia granules and powdered phenolic resin are poured into a planetary mixer according to the above ratio and mixed for 2 minutes. Then, liquid phenolic resin is added and mixed for 5 minutes. Next, fine powders of magnesium oxide and chromium oxide are added according to the above ratio and mixed for 15 minutes to obtain a uniformly mixed material. The uniformly mixed material is isostatically pressed into brick blanks of the corresponding size, and then dried in a drying tunnel at a temperature of 200℃. After 48 hours, sample A is obtained. Sample A is sent to a kiln for firing at a firing temperature of 1800℃ for 48 hours to obtain the magnesia-based permeable brick. Table 3 shows the physicochemical properties of the obtained magnesia-based permeable bricks after firing.

[0070] Table 3

[0071]

[0072] Example 4

[0073] Magnesia granules: particle size greater than 0.5 mm and less than or equal to 1 mm, 80 kg;

[0074] Magnesium oxide fine powder: particle size greater than 0.045 mm and less than or equal to 0.088 mm, 10 kg;

[0075] The performance additives are fine chromium oxide powder and fine zirconium oxide powder; the binder is phenolic resin (including powdered phenolic resin and liquid phenolic resin).

[0076] Chromium oxide fine powder: particle size less than or equal to 0.045 mm, 7 kg;

[0077] Zirconia fine powder: particle size less than or equal to 0.045 mm, 3 kg;

[0078] Powdered phenolic resin: 0.5 kg;

[0079] Liquid phenolic resin: 5kg;

[0080] The above-mentioned process for manufacturing magnesia-based permeable bricks for steel ladles is as follows: Magnesia granules and powdered phenolic resin are poured into a planetary mixer according to the above ratio and mixed for 2 minutes. Then, liquid phenolic resin is added and mixed for 5 minutes. Next, fine powders of magnesium oxide, chromium oxide, and zirconium oxide are added according to the above ratio and mixed for 15 minutes to obtain a uniformly mixed material. The uniformly mixed material is then formed into brick blanks of the corresponding size using isostatic pressing. These blanks are then dried in a drying chamber at 170℃. After 48 hours, sample A is obtained. Sample A is then fired in a kiln at 1700℃ for 48 hours to obtain the magnesia-based permeable brick. Table 4 shows the physicochemical properties of the obtained magnesia-based permeable bricks after firing.

[0081] Table 4

[0082]

[0083] Example 5

[0084] For steel ladle dispersion-type magnesia-based permeable bricks, the raw materials shall be weighed according to the following mass fractions:

[0085] Magnesia granules: particle size greater than 0.15mm and less than or equal to 1mm, 75kg;

[0086] Magnesium oxide fine powder: particle size greater than 0.020 mm and less than or equal to 0.044 mm, 15 kg;

[0087] The performance additive is zirconium oxide, with 20 kg of zirconium oxychloride octahydrate added based on the production of 7.65 kg of zirconium oxide; the binder is pulp powder; pulp powder: 3 kg;

[0088] Before mixing, zirconium oxide is coated onto the surface of magnesia particles: Magnesia particles are added to 150 kg of water and stirred evenly. Then, 20 kg of zirconium oxychloride octahydrate (ZrOCI₂·8H₂O) is added, and stirring continues for 20 minutes. The mixture is then dried at 150℃ for 15 hours, followed by a further increase to 500℃ and a holding time of 15 hours, thus achieving zirconium oxide coating on the surface of the magnesia particles. This mixture is then added to a mixer with a binder and mixed for 2 minutes. 4 kg of water is added and mixing continues for 4 minutes. Finally, fine magnesia powder is added and mixing continues for 12 minutes to obtain a uniformly mixed material.

[0089] The uniformly mixed materials were formed into brick blanks of the corresponding size using a hydraulic press, and then dried in a drying tunnel at 110℃. After 72 hours, sample A was obtained. Sample A was then sent to a kiln for firing at 1600℃ for 72 hours, thus obtaining the magnesia permeable brick. Table 5 shows the physicochemical properties of the obtained magnesia permeable brick after firing.

[0090] Table 5

[0091]

[0092] In this embodiment, chromium oxide is omitted, and only zirconium oxide is used as a performance additive. Zirconium oxychloride is hydrolyzed in water to form a gel-like zirconium oxide hydrate (ZrO2·xH2O), which then uniformly coats the surface of magnesia particles. During high-temperature heating, the zirconium oxide reacts in situ with calcium oxide in the magnesia to form a calcium zirconate phase (CaZrO3). The compressive strength increases to 40 MPa, significantly enhancing the strength of the pore walls in the permeable brick, reducing the risk of pore wall collapse and damage, improving the pore wall's resistance to erosion, enhancing the overall strength of the permeable brick, and extending its service life.

[0093] Example 6

[0094] In this embodiment, the surface of the magnesium sand particles is first modified, and then performance additives are coated on them.

[0095] For steel ladle dispersion-type magnesia-based permeable bricks, the raw materials shall be weighed according to the following mass fractions:

[0096] Magnesia granules: particle size greater than 0.5 mm and less than or equal to 1 mm, 75 kg;

[0097] Magnesium oxide fine powder: particle size greater than 0.045 mm and less than or equal to 0.088 mm, 15 kg;

[0098] The performance additives are zirconium oxide (10 kg of zirconium oxychloride octahydrate is added based on the production of 3.82 kg of zirconium oxide) and magnesium aluminum spinel (generated after adding aluminum chloride and undergoing multiple reactions, 8 kg of aluminum chloride is added based on the production of 4.26 kg of magnesium aluminum spinel); the binder is pulp powder.

[0099] Pulp powder: 3kg;

[0100] Before mixing, 15 kg of chitin was added to the magnesia particles and mixed evenly. Then, the magnesia particles were added to 150 kg of water and stirred evenly. Next, 10 kg of zirconium oxychloride octahydrate (ZrOCI2·8H2O) and 8 kg of aluminum chloride were added, and stirring was continued for 20 minutes. Then, the mixture was dried at 150℃ for 15 hours, followed by heating to 500℃ and holding for 15 hours, thus achieving zirconium oxide coating on the surface of the magnesia particles. The mixture was then mixed with a binder and added to a mixer and mixed for 2 minutes. 4 kg of water was added and the mixture was continued for 4 minutes. Finally, fine magnesia powder was added and the mixture was continued for 12 minutes to obtain a uniformly mixed material.

[0101] The uniformly mixed materials were formed into brick blanks of the corresponding size using a hydraulic press, and then dried in a drying tunnel at 110℃. After 72 hours, sample A was obtained. Sample A was then sent to a kiln for firing at 1600℃ for 72 hours, thus obtaining the magnesia permeable brick. Table 6 shows the physicochemical properties of the obtained magnesia permeable brick after firing.

[0102] Table 6

[0103]

[0104] Considering that both zirconia gel and aluminum hydroxide gel are positively charged, in this embodiment, chitosan is first mixed with magnesia particles. This causes the magnesia particles to become negatively charged in water under the influence of chitosan, allowing the zirconia gel and aluminum hydroxide gel to more uniformly coat the surface of the magnesia particles. During high-temperature heating, zirconia reacts in situ with calcium oxide in the magnesia to form calcium zirconate phase (CaZrO3), aluminum hydroxide gel forms Al2O3, and aluminum oxide reacts in situ with magnesium oxide to form magnesium aluminum spinel phase (chemical formula: MgAl2O4). This further improves the compressive strength. In this embodiment, the compressive strength reaches 48 MPa, and the air permeability is not significantly reduced.

[0105] Table 7 below is a summary table of the physicochemical properties of Examples 1-6.

[0106] Table 7

[0107]

[0108] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A dispersed magnesia-based permeable brick for steel ladles, characterized in that, It is composed of the following raw materials in parts by weight: 70-90 parts by weight of magnesia particles, 5-25 parts by weight of fine magnesium oxide powder, 0-20 parts by weight of performance additives and 1-8 parts by weight of binder. The particle size range of magnesia is greater than 0.5 mm and less than or equal to 1 mm; The particle size range of magnesium oxide fine powder is greater than 0.045 mm and less than or equal to 0.088 mm; The particle size range of the performance additives is less than or equal to 0.045 mm.

2. The dispersed magnesia-based permeable brick for steel ladles according to claim 1, characterized in that, The MgO content in the magnesia particles and the fine magnesium oxide powder is greater than 96 wt%.

3. The dispersed magnesia-based permeable brick for steel ladles according to claim 1, characterized in that, The performance additive is one or more of chromium oxide fine powder, magnesium aluminum spinel fine powder, and zirconium oxide fine powder; the chromium oxide fine powder is 0-20 parts by weight, the magnesium aluminum spinel fine powder is 0-20 parts by weight, and the zirconium oxide fine powder is 0-20 parts by weight.

4. The dispersed magnesia-based permeable brick for steel ladles according to claim 1, characterized in that, The binder is one or more of lignosulfonate, starch, phenolic resin, epoxy resin, dextrin, and pulp powder; the amount of lignosulfonate is 1-5 parts by weight, the amount of starch is 1-5 parts by weight, the amount of phenolic resin is 1-5 parts by weight, the amount of epoxy resin is 1-5 parts by weight, the amount of dextrin is 1-5 parts by weight, and the amount of pulp powder is 1-5 parts by weight.

5. The method for preparing the dispersed magnesia-based permeable brick for steel ladles according to claims 1-4, characterized in that, Includes the following steps: (1) Prepare raw materials according to the formulation of the dispersion-type magnesia permeable brick according to any one of claims 1-4; (2) Mix magnesia particles, fine magnesium oxide powder, binder and performance additives and knead them to obtain a uniformly mixed material; (3) The uniformly mixed materials are pressed into brick blanks of the corresponding size by machine pressing or isostatic pressing. (4) The blank bricks are sent into the drying hole for drying to obtain sample A. The drying temperature is 110-200℃ and the drying time is 24-72 hours. (5) The sample A is sent into a shuttle kiln or tunnel kiln for firing at a temperature of 1600-1800℃ for 48-72 hours to obtain a dispersed magnesia permeable brick for steel ladle.

6. The method for preparing dispersed magnesia permeable bricks for steel ladles according to claim 5, characterized in that, In step (2): The binder includes powdered phenolic resin and liquid phenolic resin. Magnesia particles and powdered phenolic resin are added to a mixer and mixed for 1 to 3 minutes. Liquid phenolic resin is added and mixed for another 3 to 5 minutes. Then, fine magnesium oxide powder and performance additives are added and mixed for another 10 to 15 minutes to obtain a uniformly mixed material.

7. The method for preparing dispersed magnesia permeable bricks for steel ladles according to claim 6, characterized in that, In step (2), before mixing, the fine zirconium oxide powder is coated on the surface of the magnesia particles: the magnesia particles are added to 100-200 parts by weight of water and stirred evenly. Then, 3-30 parts by weight of zirconium oxychloride octahydrate ZrOCI2·8H2O are added and stirred for 15-20 minutes. Then, the particles are dried at a temperature of 150-200℃ for 12-20 hours. The temperature is then raised to 500-600℃ and held for 12-15 hours, thereby achieving the coating of zirconium oxide on the surface of the magnesia particles.

8. The method for preparing dispersed magnesia permeable bricks for steel ladles according to claim 6, characterized in that, In step (2), before mixing, the fine powders of zirconia and magnesium aluminum spinel are coated on the surface of the magnesia particles: the magnesia particles are added to 100-200 parts by weight of water and stirred evenly. Then, 3-30 parts by weight of zirconium oxychloride octahydrate ZrOCI2·8H2O and 2-10 parts by weight of aluminum chloride are added and stirred for 15-20 minutes. Then, the particles are dried at a temperature of 150-200℃ and then heated to 500-600℃ for 12-15 hours, thereby achieving the coating of zirconia and magnesium aluminum spinel on the surface of the magnesia particles.

9. The method for preparing dispersed magnesia permeable bricks for steel ladles according to claim 6, characterized in that, Chitosan is mixed evenly with magnesia particles before the performance additive is coated onto them.

10. The method for preparing dispersed magnesia-based permeable bricks for steel ladles according to claim 9, characterized in that, The amount of chitosan added is 5 to 20 parts by weight.

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