A kind of air-permeable brick for "plum blossom pile" type composite ladle and preparation method thereof

Abstract

The present invention relates to a "plum blossom pile" type air-permeable brick for composite ladle and a preparation method thereof, wherein the air-permeable brick comprises a dispersion block, a castable, a cover plate, an air chamber, a steel shell, and a slit, wherein the dispersion blocks are evenly and spacedly arranged from the center to the outer circle, the castable is filled between the dispersion blocks, the slits are evenly distributed in the castable, the steel shell is wrapped at the outermost part of the air-permeable brick, the cover plate is at the bottom of the air-permeable brick, and an air chamber is left between the dispersion block, the castable and the cover plate. The air-permeable brick produced by the present invention has good air flow stability and uniformity, large gas ventilation volume, high-strength brick body, good anti-permeability and thermal vibration stability, and a long service life.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical refractory materials, and in particular to a "plum blossom pile" type air-permeable brick for a composite ladle and a preparation method thereof. Background Art

[0002] With the development of science and technology, people's demand for high-quality steel and special steel is increasing. However, the presence of inclusions in steel has a serious impact on the quality and performance of steel, which greatly limits the development of high-quality steel and special steel. Out-of-furnace refining technology is the most important measure to improve the quality of steel. The air brick is a key functional element of out-of-furnace refining. Its function is to homogenize the temperature of molten steel, remove non-metallic inclusions in molten steel, promote gas floating, and promote metallurgical reactions, thereby playing a role in cleaning molten steel and improving steel quality. With the gradual enlargement of the ladle, the increase in smelting temperature and the extension of smelting time, the use environment of refractory materials is becoming more and more severe, which puts higher requirements on refractory materials for ladle. Due to the special position and environment of air bricks in the ladle, the life, blowing success rate and air permeability are required to be high. How to improve the blowing rate and life so that it is synchronized with the service life of the ladle lining or ladle bottom refractory materials is our common research topic.

[0003] At present, there are two main types of ladle air bricks: diffuse type and slit type.

[0004] 1. Dispersed air brick: Dispersed air brick has interpenetrating pores of different sizes distributed inside. These micron-sized curved channels create a large resistance to the penetration of molten steel. In actual use, there is basically no steel penetration, achieving the purpose of bottom blowing. These pores are irregularly distributed inside the air brick, and the sizes are also different. The formation of pores is mainly through the accumulation of particles, resulting in interconnected dispersed pores. Dispersed air bricks have a large number of uniform bubbles during blowing, good refining effect, and a blowing rate of more than 99.9%. Due to the characteristics of the ingredients of the dispersed air brick, the air channel is formed through the gaps between the particles. The entire brick body is not dense, and the brick body has low strength. During the oxygen blowing, cleaning and use process, the anti-scouring ability is poor, resulting in a reduced service life; secondly, when refining requires a large blowing flow, the air permeability of the dispersed air brick is not easy to adjust, which limits the promotion and application of the dispersed air brick.

[0005] 2. Slit-type breathable bricks: Slit-type breathable bricks are the main type of breathable bricks currently used in steel mills. The ventilation principle is to ventilate through the slits formed by high-temperature firing of burnable fillers. Slit-type breathable bricks have the advantages of high brick strength, wide air supply flow adjustment range, stable airflow, and bubbles are not easy to gather during blowing. However, it is common that the slit cannot be blown through due to the uncontrollable factors of the burnable fillers and whether the design of the slit matches the use conditions of the steel mill. Secondly, the thermal shock resistance of the overly dense brick core is poor, and it is more sensitive to the temperature changes of the rapid cooling and heating of the ladle, which causes the transverse fracture of the breathable brick and thus affects the service life of the breathable brick.

[0006] The patent document with application publication number CN 106392047 A discloses a "composite slit breathable brick and its preparation method". The composite slit breathable brick adopts a composite structure of breathable bricks and slits. Because the side that contacts molten steel during its working process is a single dispersed block structure, its damage mechanism is similar to that of a single dispersed breathable brick or a single slit breathable brick. The shortcomings of the slit breathable brick, such as poor thermal vibration performance and poor corrosion resistance of the dispersed breathable brick, have not been improved.

[0007] The patent document with application publication number CN 111889663 A discloses "a composite diffused air-permeable brick and its preparation method". The air-permeable brick is a diffused block in the middle and a slit on the outside. In fact, the cross section of the composite air-permeable brick is concentrated with a large proportion of single structure. During its use, the diffused block part will show the disadvantage of poor erosion resistance, while the slit part will show the disadvantage of poor thermal vibration performance. The difference between the two is too obvious and cannot form complementary advantages. Eventually, the single diffused block part or the slit part will be offline due to the short height.

[0008] Based on the advantages and disadvantages of the above various types of air bricks, there is an urgent need for a new type of ladle air brick and a manufacturing method, which has good air flow stability, high-strength brick body, good anti-permeability and thermal vibration stability, and a longer service life. Summary of the invention

[0009] The present invention provides a "plum blossom pile" type air-permeable brick for a composite ladle and a preparation method thereof, aiming to make it have good air flow stability and uniformity, large gas ventilation volume, high-strength brick body, good anti-permeability and thermal vibration stability, and long service life.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A "plum blossom pile" type air-permeable brick for a composite ladle comprises a dispersion block, a castable, a cover plate, an air chamber, a steel shell and a slit. The dispersion blocks are evenly and spaced apart and arranged in sequence from the center to the outer circle, the castable is filled between the dispersion blocks, the slits are evenly distributed in the castable, the steel shell is wrapped at the outermost part of the air-permeable brick, the cover plate is at the bottom of the air-permeable brick, and an air chamber is left between the dispersion blocks, the castable and the cover plate.

[0012] The total cross-sectional area of ​​the dispersion blocks accounts for 35%-70% of the total cross-sectional area of ​​the air-permeable brick.

[0013] The cross-sectional shape of the dispersion block is rectangular, trapezoidal or circular.

[0014] The slits are arranged in the same direction as the diameter direction of the air-permeable brick, or the slits are arranged in a direction perpendicular to the diameter direction of the air-permeable brick.

[0015] The distance between the slits is not less than 15 mm, the width of a single slit is between 12-40 mm, and the thickness is between 0.165-0.2 mm; the total number of the slits is 10-45.

[0016] The distance between the slit and the diffusion block is not less than 15 mm.

[0017] The dispersion block is prepared from the following raw materials in parts by weight: 25-35 parts of white corundum with a particle size of 1-0.5 mm, 20-30 parts of plate corundum with a particle size of 1-0.5 mm, 20-30 parts of fused mullite with a particle size of 1-0.5 mm, 3-8 parts of 325 mesh zirconium oxide, 3-6 parts of 2 μm active alumina powder, 1-3 parts of 500 mesh chromium oxide green, 0.5-3 parts of silicon dioxide powder, 0.5-1 parts of 325 mesh lanthanum oxide, and 0.2-0.8 parts of etherified starch.

[0018] The castable is prepared from the following raw materials in parts by weight: 15-30 parts of plate-shaped corundum with a particle size of 6-3 mm, 10-20 parts of plate-shaped corundum with a particle size of 3-1 mm, 5-15 parts of plate-shaped corundum with a particle size of 1-0 mm, 8-15 parts of plate-shaped corundum with a particle size of 325 mesh, 5-10 parts of sintered spinel with a particle size of 1-0 mm, 5-10 parts of sintered spinel with a particle size of 325 mesh, 3-8 parts of zirconia with a particle size of 325 mesh, 3-8 parts of active alumina powder with a particle size of 2 μm, 3-8 parts of calcined alumina powder with a particle size of 5 μm, 3-8 parts of CA-70 cement, 1-3 parts of chromium oxide green with a particle size of 500 mesh, 0.5-1.5 parts of cerium oxide with a particle size of 200 mesh, 0.2-1 parts of silicon dioxide powder, 0.08-0.15 parts of explosion-proof fiber, and 0.2-0.4 parts of dispersant.

[0019] A method for preparing a "plum blossom pile" type air-permeable brick for a composite ladle, comprising the following method:

[0020] 1) Making a dispersion block: preparing a binder and mixing the material in the binder, sealing the material and placing it for 24 hours, pressing it into a sample block under a hydraulic press at 100-150Mpa, or using an isostatic pressing process to hold a pressure of 100-200Mpa for 90-250 seconds to make a sample block, placing the sample block at room temperature for 24 hours, drying the sample block at 180°C for 18 hours, and firing the dried dispersion block in a high-temperature kiln at a firing temperature of 1580-1720°C for more than 10 hours; and then processing it into a dispersion block of a desired size;

[0021] 2) Fix the manufactured dispersion blocks and combustible fillers in the set positions inside the steel shell according to the design requirements, and cast them into a whole with casting material;

[0022] 3) The air brick core is cured in the mold for 15-30 hours, and then demolded and cured for 24-72 hours. The curing temperature is 25-40°C and the curing humidity is 60-80%. The air brick core with steel shell is dried at 400-600°C. During the drying process, the slit direction of the air brick needs to be placed perpendicular to the ground.

[0023] 4) Weld the dried air-permeable brick core with steel shell to the air inlet pipe and cover plate.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The composite ladle air bricks with the dispersion blocks and the castables arranged in a "plum blossom pile" style in the present invention can make the air bricks blow out a large number of small bubbles, improve the ability to remove fine inclusions in molten steel, and embody the advantages of the slit air bricks with large gas flow and easy adjustment, ensure the gas flow of the air bricks, improve the air flow stability, and greatly improve the blowing rate of the air bricks;

[0026] 2. The composite ladle air bricks with dispersed blocks and castables arranged in a "plum blossom pile" style in the present invention improve the shortcomings of single dispersed air bricks, that is, bubbles are easily gathered and air flow is unstable during blowing. Due to the slits formed by the distribution of several casts, the slit air bricks mainly rely on the circulation flow, which increases the agitation of the molten steel by the gas, so that the impurity removal effect is better and the energy consumption is reduced;

[0027] 3. The composite ladle air bricks in which the dispersion blocks and the castables are arranged in a "plum blossom pile" style are used in the present invention. Compared with the slit air bricks, the thermal shock stability of the whole air bricks is greatly improved; the single slit air brick core is improved. Since the castable is too dense, it is more sensitive to the temperature changes of the ladle due to rapid cooling and heating, and the thermal stress inside the brick cannot be released, resulting in transverse fracture of the air brick and further affecting it; due to the distribution of several dispersion blocks, the castable part is divided into several small pieces, the thermal stress generated is small, and it can be timely transmitted to the nearby dispersion block part, and the dispersion block is porous, which greatly releases the thermal stress of the air brick.

[0028] 4. The castable formula adopted by the present invention increases the thermal shock stability, high temperature strength and corrosion resistance of the castable. The castable of the present invention achieves the above purpose by adding raw materials such as cerium oxide and zirconium oxide. The addition of zirconium oxide improves the thermal shock stability of the castable, and the addition of a certain proportion of cerium oxide will cause the zirconium oxide to transform from a monoclinic phase to a cubic phase under high temperature conditions. A certain proportion of cubic phase and monoclinic phase composite zirconium oxide will improve its thermal shock stability and compressive strength, wherein cerium oxide plays the role of a stabilizer; the addition of cerium oxide can significantly improve the corrosion of impurities such as vanadium and manganese, and the internal pore structure of the castable can also be improved under the action of cerium oxide and silicon, maintaining the volume stability of the castable.

[0029] 5. The dispersion block formula adopted in the present invention effectively improves the anti-scouring ability and anti-penetration performance of the dispersion block. By adding chromium oxide green and lanthanum oxide, the wetting performance of the refractory in molten steel is effectively improved under the action of corundum and microsilica powder at high temperature, thereby improving the anti-scouring ability and anti-penetration performance; the dispersion block combined with aluminum dihydrogen phosphate effectively improves the strength of its matrix part at high temperature; and in the present invention, since the cross-section of a single dispersion block is small, the dispersion block and the castable are arranged in a "plum blossom pile" manner, so that the erosion of the molten steel on the dispersion block part is reduced.

[0030] 6. Compared with the upper and lower composite structures or the inner and outer composite structures in the prior art, the composite ladle air-permeable brick structure in which the dispersion blocks and the castables are arranged in a "plum blossom pile" style in the present invention has better thermal vibration stability and anti-erosion and scouring capabilities; the dispersion block formula used in the present invention effectively improves the anti-scouring and anti-penetration performance of the dispersion blocks, and the combination of the dispersion blocks and the castables complements each other's advantages, which greatly improves the overall thermal shock stability of the air-permeable bricks.

[0031] 7. The composite ladle air bricks in which the dispersion blocks and the castables are arranged in a "plum blossom pile" style in the present invention can greatly reduce the number of times the air bricks are purged, reduce the labor intensity of workers, and greatly improve the service life of the air bricks; when the air bricks used in the present invention are used without a purging process, the dispersion block part can be blown well and continuously, and although a part of inclusions will remain in the slit part, due to the shallow depth of the slit inclusions and the combined effect of the external gas pressure and the higher temperature of the molten steel in the ladle, the slit inclusions can be easily blown out and the normal blowing work can be restored. This method reduces the number of purging times for the operating workers and reduces the labor intensity of the workers; secondly, taking the 90-ton ladle of the second branch of a large steel plant in Northeast China as an example, the average service life of the original air bricks is 12.64 times / piece, while the average service life of the air bricks using the present invention is 20.42 times / piece, and the service life is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1It is a schematic diagram of the overall structure of the air-permeable bricks for the "plum blossom pile" type composite ladle of the present invention.

[0033] Figure 2 It is a schematic diagram (three circles) of the "plum blossom pile" structure arrangement of the cross section of the composite ladle air permeable brick of the present invention.

[0034] Figure 3 It is a schematic diagram of the "plum blossom pile" structural arrangement of the cross section of the composite ladle air permeable brick of the present invention (two circles).

[0035] Figure 4 It is a process flow chart of the preparation method of the air-permeable brick for the "plum blossom pile" type composite ladle of the present invention.

[0036] Figure 5 This is an enlarged cross-sectional view of the slit.

[0037] In the figure: 1. air inlet pipe; 2. cover plate; 3. steel shell; 4. slit; 5. diffusion block; 6. air chamber; 7. castable;. DETAILED DESCRIPTION

[0038] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0039] See Figure 1-Figure 3 A "plum blossom pile" type air-permeable brick for a composite ladle comprises a dispersion block 5, a castable 7, a cover plate 2, an air chamber 6, a steel shell 3 and a slit 4. The dispersion blocks 5 are evenly and spacedly arranged from the center to the outer circle, the castable 7 is filled between the dispersion blocks 5, the slits 4 are evenly distributed in the castable 7 and are formed by high-temperature firing of a burnable filler, the steel shell 3 is wrapped at the outermost part of the air-permeable brick, the cover plate 2 is at the bottom of the air-permeable brick, and an air chamber is left between the dispersion blocks 5, the castable 7 and the cover plate 2.

[0040] The total cross-sectional area of ​​the dispersion blocks 5 accounts for 35%-70% of the total cross-sectional area of ​​the air-permeable brick.

[0041] The cross-sectional shape of the diffusion block 5 is rectangular, trapezoidal or circular.

[0042] The slit 4 is arranged in the same direction as the diameter direction of the air-permeable brick, or the slit 4 is arranged in a direction perpendicular to the diameter direction of the air-permeable brick.

[0043] The distance between the slits is not less than 15 mm, the width b of a single slit is between 12-40 mm, and the thickness a is between 0.165-0.2 mm (see Figure 5 ); the total number of the slits is 10-45.

[0044] The distance between the slit 4 and the diffusion block 5 is not less than 15 mm.

[0045] The present invention changes the original single diffused block structure or single slit structure of the air-permeable brick core, adopts a composite air-permeable brick of diffused blocks 5 and slits 4, and adopts a method of evenly distributing a plurality of diffused blocks 5 in various places of the air-permeable brick core in a "plum blossom pile" manner, and the diffused blocks 5 are fixed inside the steel shell 3 by a positioning device; the fixed dispersed diffused blocks 5 are cast into a whole by a castable 7, and the slits 4 are made in the part where the castable 7 is located by a combustible filler; the slits 4 should be evenly dispersed in various places of the air-permeable brick core; the air chamber 6 is cast and formed by the castable 7; the casted air-permeable brick core is cured and dried, and finally assembled and welded into a finished product.

[0046] The length of the dispersion block 5 in the composite ladle air brick refers to the length from the air chamber 6 to the top. The arrangement of the small dispersion blocks 5 adopts a "plum blossom pile" arrangement, which is evenly and spaced apart from the center to the outer circle. The dispersion blocks 5 can be designed and arranged in 2-6 circles according to actual conditions.

[0047] The air chamber 6 is located at the bottom of the air-permeable brick core and is cast by a castable 7 . The contact surface of the air chamber 6 should cover all the diffusion blocks 5 and the slits 4 .

[0048] The dispersion block 5 is prepared from the following raw materials in parts by weight: 25-35 parts of white corundum with a particle size of 1-0.5 mm, 20-30 parts of plate corundum with a particle size of 1-0.5 mm, 20-30 parts of fused mullite with a particle size of 1-0.5 mm, 3-8 parts of 325 mesh zirconium oxide, 3-6 parts of 2 μm active alumina powder, 1-3 parts of 500 mesh chromium oxide green, 0.5-3 parts of silicon dioxide powder, 0.5-1 parts of 325 mesh lanthanum oxide, and 0.2-0.8 parts of etherified starch.

[0049] The castable 7 is prepared from the following raw materials in parts by weight: 15-30 parts of plate-like corundum with a particle size of 6-3mm, 10-20 parts of plate-like corundum with a particle size of 3-1mm, 5-15 parts of plate-like corundum with a particle size of 1-0mm, 8-15 parts of plate-like corundum with a particle size of 325 mesh, 5-10 parts of sintered spinel with a particle size of 1-0mm, 5-10 parts of sintered spinel with a particle size of 325 mesh, 3-8 parts of zirconia with a particle size of 325 mesh, 3-8 parts of active alumina powder with a particle size of 2μm, 3-8 parts of calcined alumina powder with a particle size of 5μm, 3-8 parts of CA-70 cement, 1-3 parts of chromium oxide green with a particle size of 500 mesh, 0.5-1.5 parts of cerium oxide with a particle size of 200 mesh, 0.2-1 parts of silicon dioxide powder, 0.08-0.15 parts of explosion-proof fiber, and 0.2-0.4 parts of dispersant.

[0050] The powder part of the castable 7 in the ingredients needs to be pre-milled for more than 5 minutes to make a premixed powder. When mixing, the aggregate and the powder need to be mixed in a high-speed mixer for 3 minutes, and then 4%-6% water (as a percentage of the mass of the castable) is added and mixed for 3 minutes to make the material evenly dispersed, have a certain fluidity, and not separate the material and water. After mixing, it can be poured.

[0051] Castable material 7 production index requirements are as follows: volume density 3.0-3.15g / cm 3 , apparent porosity ≤10%, 1600℃ permanent linear change rate ±0.15%, 1400℃ flexural strength ≥30Mpa, 1400℃ compressive strength ≥90Mpa.

[0052] A method for preparing a "plum blossom pile" type air-permeable brick for a composite ladle, comprising the following method:

[0053] 1) Preparation of dispersion block 5: The powder in the ingredients needs to be pre-milled for more than 5 minutes to make pre-mixed powder; when mixing, first put the etherified starch in liquid aluminum dihydrogen phosphate or phosphoric acid solution and stir evenly to make a binder, and the aggregate needs to be pre-mixed for 2 minutes. During production, the aggregate and binder are first mixed in a high-speed mixer for 5 minutes, and then all the matrix materials are added and mixed for 15 minutes before discharging. After the material is sealed and placed for 24 hours, it is pressed into a sample block under 100-150Mpa under a 200t hydraulic press, or an isostatic pressing process is used to maintain a pressure of 100-200Mpa for 90-250 seconds to make a sample block. After the sample block is placed at room temperature for 24 hours, the sample block is dried at 180℃ for 18 hours. The dried dispersion block needs to be fired in a high-temperature kiln at a firing temperature of 1580-1720℃ for more than 10 hours; and then processed into a dispersion block 5 of the required size.

[0054] The dispersion block 5 produced by this process has the following index requirements: volume density 2.8-3.1g / cm 3 , apparent porosity 26%-35%, 1600℃ permanent linear change rate ±0.15 / %, 1400℃ flexural strength ≥20Mpa, 1400℃ compressive strength ≥60Mpa.

[0055] 2) The several dispersion blocks 5 and combustible fillers are fixed at set positions inside the steel shell 3 according to the design requirements, and cast into a whole with the casting material 7.

[0056] 3) The breathable brick core with the steel shell 3 after casting is subjected to a curing and drying process: the breathable brick core is cured in the mold for 15-30 hours, and demolded and cured for 24-72 hours, the curing temperature is 25-40°C, and the curing humidity is 60-80%; the breathable brick core with the steel shell 3 after curing is dried at 400-600°C to discharge the moisture inside the breathable brick core, improve the strength of the breathable brick core blank, and melt and burn the internal combustible filler to form a continuous and stable slit 4; during the drying process, the slit direction of the breathable brick needs to be placed perpendicular to the ground.

[0057] 4) The dried air-permeable brick core with steel shell 3 is welded together with the air inlet pipe 1 and the cover plate 2, and the process is completed after being tested by the gas detection device to be qualified.

[0058] Embodiment 1:

[0059] Taking a 90-ton ladle of the second branch of a large steel plant in Northeast China as an example, the present invention specifically describes a "plum blossom pile" type composite ladle air-permeable brick and its production process.

[0060] The second branch of the steel plant has been using ladle bottom blowing technology for more than 20 years, and its service life has been unstable. Especially in recent years, due to the increase in the proportion of special steel grades such as silicon steel and ultra-low carbon steel, the increase in smelting time, the deterioration of smelting environment and other factors, the requirements for breathable bricks have become more and more stringent, the ventilation airflow of breathable bricks is unstable, and the number of abnormalities such as broken bricks and excessive erosion has increased significantly.

[0061] Based on long-term observation and a large number of tests, the present invention improves the ladle air brick as follows:

[0062] The composite air-permeable bricks with dispersion blocks and slits are adopted, and a structure is adopted in which several dispersion blocks are evenly distributed in the form of "plum blossom piles", and the air-permeable bricks are cast with the aid of castables. The air-permeable bricks used in the steel plant have a bottom diameter of 140mm, an upper diameter of 197mm, and a brick body height of 408mm. Figure 3 As shown in the structure, the dispersion blocks 5 are divided into two circles of dispersed structures. The inner core dispersion blocks in the inner circle have dimensions: a square with a side length of 38 mm in cross section and a height of 400 mm; the outer circle dispersion blocks 5 have dimensions: 5 rectangles with a cross section of 35*25 mm and a height of 400 mm; the dispersion blocks 5 are evenly distributed, and the total number of slits 4 in the outer circle is 10, with 2 slits evenly distributed between every two dispersion blocks 5.

[0063] Castable 7 is prepared using the following raw materials in parts by weight: 25 parts of 6-3mm plate-shaped corundum particle size, 20 parts of 3-1mm plate-shaped corundum particle size, 15 parts of 1-0mm plate-shaped corundum particle size, 8.5 parts of 325 mesh plate-shaped corundum, 5 parts of 1-0mm sintered spinel, 5 parts of 325 mesh sintered spinel, 5 parts of 325 mesh zirconium oxide, 4 parts of 2μm activated alumina powder, 4 parts of 5μm calcined alumina powder, 5 parts of CA-70 cement, 2 parts of 500 mesh chromium oxide green, 0.5 parts of 200 mesh cerium oxide, 0.5 parts of silica powder, 0.1 parts of explosion-proof fiber, and 0.4 parts of dispersant.

[0064] The dispersion block 5 is prepared from the following raw materials in parts by weight: 30 parts of white corundum with a particle size of 1-0.5 mm, 30 parts of plate-shaped corundum with a particle size of 1-0.5 mm, 25 parts of fused mullite with a particle size of 1-0.5 mm, 5 parts of 325 mesh zirconium oxide, 6 parts of 2 μm activated alumina powder, 2 parts of 500 mesh chromium oxide green, 0.5 parts of silicon dioxide powder, 1 part of 325 mesh lanthanum oxide, 0.5 parts of etherified starch, and aluminum dihydrogen phosphate or phosphoric acid solution are determined by the stirring state of the materials, and their weight fractions are not counted.

[0065] Implementation effect:

[0066] 1. The service life is significantly improved: According to the usage data statistics from February to August 2021, the average service life of the original breathable bricks is 12.64 times / piece, while the average service life of the breathable bricks using the present invention is 20.42 times / piece.

[0067] 2. The thermal shock resistance and erosion resistance are significantly improved: According to the usage data statistics from February to August 2021, almost no products were taken offline due to peeling. Through the statistics of the residual thickness of the breathable bricks after use, the average erosion rate of the original breathable bricks was 17.2 mm / time, while the average erosion rate of the breathable bricks of the present invention was 9.43 mm / time.

[0068] 3. The blowing rate is significantly improved: According to the usage data statistics from February to August this year, the average blowing rate of the original air-permeable bricks is 94.71%, while the average blowing rate of the air-permeable bricks using the present invention is 99.94%.

[0069] 4. The number of times the air bricks are purged is reduced: the original slit-type air bricks need to be purged each time they are used, while the air bricks of the present invention need to be purged once every 3-5 times they are used.

Claims

1. A "plum blossom pile" type air-permeable brick for composite ladle, characterized in that: It includes a dispersion block, a castable, a cover plate, an air chamber, a steel shell, and a slit. The dispersion blocks are evenly and spaced apart from the center to the outer circle, the castable is filled between the dispersion blocks, the slits are evenly distributed in the castable, the steel shell is wrapped at the outermost part of the air-permeable brick, the cover plate is at the bottom of the air-permeable brick, and an air chamber is left between the dispersion block, the castable and the cover plate; The total cross-sectional area of ​​the dispersion blocks accounts for 35%-70% of the total cross-sectional area of ​​the air-permeable brick; The slits are arranged in the same direction as the diameter direction of the air-permeable brick, or the slits are arranged in a direction perpendicular to the diameter direction of the air-permeable brick.

2. The "plum blossom pile" type composite ladle air-permeable brick according to claim 1, characterized in that: The cross-sectional shape of the dispersion block is rectangular, trapezoidal or circular.

3. The "plum blossom pile" type composite ladle air-permeable brick according to claim 1, characterized in that: The distance between the slits is not less than 15 mm, the width of a single slit is between 12-40 mm, and the thickness is between 0.165-0.2 mm; the total number of the slits is 10-45.

4. A "plum blossom pile" type composite ladle air permeable brick according to claim 1 or 3, characterized in that: The distance between the slit and the diffusion block is not less than 15 mm.

5. The "plum blossom pile" type composite ladle air-permeable brick according to claim 1, characterized in that: The dispersion block is prepared from the following raw materials in parts by weight: 25-35 parts of white corundum with a particle size of 1-0.5 mm, 20-30 parts of plate corundum with a particle size of 1-0.5 mm, 20-30 parts of fused mullite with a particle size of 1-0.5 mm, 3-8 parts of 325 mesh zirconium oxide, 3-6 parts of 2 μm active alumina powder, 1-3 parts of 500 mesh chromium oxide green, 0.5-3 parts of silicon dioxide powder, 0.5-1 parts of 325 mesh lanthanum oxide, and 0.2-0.8 parts of etherified starch.

6. The "plum blossom pile" type composite ladle air-permeable brick according to claim 1, characterized in that: The castable is prepared from the following raw materials in parts by weight: 15-30 parts of plate-shaped corundum with a particle size of 6-3 mm, 10-20 parts of plate-shaped corundum with a particle size of 3-1 mm, 5-15 parts of plate-shaped corundum with a particle size of 1-0 mm, 8-15 parts of plate-shaped corundum with a particle size of 325 mesh, 5-10 parts of sintered spinel with a particle size of 1-0 mm, 5-10 parts of sintered spinel with a particle size of 325 mesh, 3-8 parts of zirconia with a particle size of 325 mesh, 3-8 parts of active alumina powder with a particle size of 2 μm, 3-8 parts of calcined alumina powder with a particle size of 5 μm, 3-8 parts of CA-70 cement, 1-3 parts of chromium oxide green with a particle size of 500 mesh, 0.5-1.5 parts of cerium oxide with a particle size of 200 mesh, 0.2-1 parts of silicon dioxide powder, 0.08-0.15 parts of explosion-proof fiber, and 0.2-0.4 parts of dispersant.

7. A method for preparing a "plum blossom pile" type air-permeable brick for a composite ladle as claimed in any one of claims 1 to 6, characterized in that: The following methods are included: 1) Making dispersion blocks: prepare a binder and mix the materials in the binder, seal the materials and place them for 24 hours, press them into sample blocks under a hydraulic press at 100-150Mpa, or use an isostatic pressing process to pressurize them at 100-200Mpa for 90-250 seconds, place the sample blocks at room temperature for 24 hours, dry them at 180℃ for 18 hours, and then fire the dried dispersion blocks in a high-temperature kiln at a firing temperature of 1580-1720℃ for more than 10 hours; then process them into dispersion blocks of the required size; 2) Fix the manufactured dispersion blocks and combustible fillers in the set positions inside the steel shell according to the design requirements, and cast them into a whole with castables; 3) The air brick core is cured in the mold for 15-30 hours, and demolded for 24-72 hours. The curing temperature is 25-40℃, and the curing humidity is 60-80%. The air brick core with steel shell is dried at 400-600℃. During the drying process, the slit direction of the air brick needs to be placed perpendicular to the ground. 4) Weld the dried breathable brick core with steel shell to the air inlet pipe and cover plate.

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