A ladle bottom argon blowing porous plug

Abstract

This invention provides a bottom-blown argon permeable brick from a steel ladle, which improves the air permeability uniformity of dispersion-type permeable bricks and has a simple manufacturing process and low cost. It includes a frustum-shaped brick core body. The upper part of the frustum-shaped brick core body has a permeable layer and an impermeable layer respectively, from the outside to the inside. The permeable layer is a frustum-shaped opening at the top, and has a frustum-shaped cavity inside, which is filled by the impermeable layer. The lower part of the frustum-shaped brick core body also has an air chamber connected to the permeable layer. The bottom of the air chamber is connected to the upper end of a ventilation channel, and the lower end of the ventilation channel extends from the bottom of the frustum-shaped brick core body.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically to a permeable brick for bottom blowing argon in steel ladles. Background Technology

[0002] Bottom-blowing argon in steel ladles is a crucial method in secondary refining. It involves blowing argon gas through permeable bricks into the molten pool, creating numerous bubbles. The buoyancy of these bubbles agitates the molten steel, promoting interfacial reactions between the steel and slag and causing inclusions to float to the surface. The number of permeable bricks at the bottom of the ladle is typically determined by the ladle's dimensions and effective volume. Adjusting the type, placement, and argon flow rate of the permeable bricks can optimize the agitation effect and refining efficiency. Currently, the main types of permeable bricks used in steel ladles are slit-type and diffused-type. Slit-type permeable bricks offer advantages such as high air permeability and long service life, but they generate large bubbles, resulting in low inclusion removal efficiency and a tendency to cause slag entrapment. Diffuse-type permeable bricks generate a large number of more uniformly sized bubbles, but suffer from lower air permeability and poor thermal shock resistance.

[0003] Chinese Patent [202120905345.7] discloses a dispersion-type integral steel ladle bottom-blown permeable brick, including a steel ladle bottom-blown permeable brick body, a dispersion-type permeable plug, a protective body, a steel shell, an upper air chamber, a safety warning device, a slit air passage, a lower air chamber, a bottom cover plate, and an air inlet pipe. This permeable brick solves the problems of low air permeability, uneven air permeability, and short service life of dispersion-type permeable bricks by increasing the air permeability area of ​​the dispersion-type permeable plug and improving the structure and molding process of the dispersion-type permeable plug. However, this patent has the following shortcomings: the excessively large dispersion-type permeable plug reduces the uniformity of air permeability, and the built-in safety warning device increases the thermal stress inside the permeable brick. The manufacturing process is complex and costly.

[0004] Chinese Patent [202210065138.4] discloses a "plum blossom pile" type composite steel ladle permeable brick and its preparation method. The permeable brick includes dispersion blocks, castable refractory, cover plate, air chamber, steel shell, and slits. The dispersion blocks are evenly and intermittently distributed from the center outwards, with castable refractory filling the spaces between them. The slits are evenly distributed within the castable refractory, and an air chamber is left between the dispersion blocks, the castable refractory, and the cover plate. The permeable brick produced by this invention has good airflow stability and uniformity, a large gas permeability, high-strength brick body, and good impermeability and thermal shock stability. However, this patent has the following shortcomings: the dispersion blocks and slits share an air chamber, causing most of the gas to flow out from the slits with smaller pressure drop, which reduces the dispersion blocks' ability to generate bubbles, thereby reducing the overall thermal shock stability of the permeable brick.

[0005] Chinese Patent [202122114362.1] discloses a non-oxygen-burning slit-type permeable brick for steel ladles, comprising a brick core with several sets of slits penetrating the top and bottom surfaces of the core. Each set of slits is arranged in a circular array centered on the axis of the core, and the slits in each set are radially distributed centered on the axis of the core. This invention shortens the slit width by uniformly dividing each slit into several narrow slit units, thereby reducing the depth of molten steel penetration into the slits, improving the blowing rate of the permeable brick, reducing the oxygen burning frequency, shortening the oxygen burning time, and improving the service life of the permeable brick. However, this patent has the following shortcomings: the bubbles generated by the slit-type permeable brick are too large, resulting in an insignificant effect on removing fine inclusions in the molten steel. Furthermore, the resulting bubble plumes have a strong impact on the steel-slag interface, easily forming slag holes and slag entrapment, thus reducing the quality of the molten steel. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a bottom-blown argon permeable brick from a steel ladle, which improves the uniformity of air permeability of the dispersed permeable brick, and has a simple manufacturing process and low cost.

[0007] The technical solution is as follows: a steel ladle bottom-blown argon permeable brick, comprising a frustum-shaped brick core body, characterized in that: the upper interior of the frustum-shaped brick core body is provided with a permeable layer and an impermeable layer from the outside to the inside, the permeable layer is a frustum-shaped opening at the top, the permeable layer has a frustum-shaped cavity inside, and the impermeable layer fills the cavity; the lower interior of the frustum-shaped brick core body is also provided with an air chamber connected to the permeable layer, the bottom of the air chamber is connected to the upper end of a ventilation channel, and the lower end of the ventilation channel extends from the bottom of the frustum-shaped brick core body.

[0008] A further feature is that the height of the breathable layer is not less than the height of the impermeable layer; The air chamber is truncated cone-shaped, and the outer diameter of the bottom of the permeable layer is greater than the inner diameter of the opening at the top of the air chamber. The airtight layer is mainly composed of aggregate, matrix powder, and binder, with a mass ratio of aggregate, matrix powder, and binder of 65-70:30-35:3.5-5. The aggregate mainly includes high-purity tabular corundum, spinel, and mullite, with the high-purity tabular corundum having a particle size range of 1.0-1.5 mm, and the spinel and mullite having a particle size range of 1.25-1.5 mm. The matrix powder consists of calcined corundum powder and flaky corundum powder, with particle sizes less than 0.045 mm and 0.088 mm, respectively. The binder is a 15-20% concentration dextrin solution. The processing of this airtight layer includes the following steps: S1. Add calcined corundum powder and flake corundum powder to a ball mill jar at a mass ratio of 1:1 and premix for 3-5 hours at a speed of 200 rpm; S2. Add aggregate, matrix powder and binder into a mixer and mix for 5-10 minutes. Use isostatic pressing under a pressure of 100-150 MPa. S3. Finally, place the formed airtight layer in a drying oven and keep it at 110 ℃ for 24 hours, then heat it at 1650 ℃ for 3 hours, and cool it to room temperature. The bulk density of the air-impermeable layer is greater than 3.2 g / cm³. 3 High temperature flexural strength ≥40 MPa, high temperature compressive strength ≥100 MPa, apparent porosity ≤5%; The breathable layer is mainly composed of aggregate, matrix powder, and binder, with a mass ratio of aggregate, matrix powder, and binder of 75~90:10~25:5~10; the aggregate mainly includes high-purity tabular corundum with a particle size range of 0.1~0.5mm; the matrix powder is calcined corundum powder and flaky corundum powder, with particle sizes less than 0.045 mm and 0.088 mm, respectively; the binder is a 10~25% concentration maltose solution. The processing of this breathable layer includes the following steps: S1. Add calcined corundum powder and flake corundum powder to a ball mill jar at a mass ratio of 1:1 and premix at 200 rpm for 3-5 hours. Then add aggregate, matrix powder and binder to a mixer and mix for 5-10 minutes. S2. Pour the mixed raw materials into a mold with an impermeable layer, and use an isostatic pressing process under a pressure of 75~100 MPa. S3. Place the formed breathable layer in a drying oven and keep it at 110 ℃ for 24 hours, then heat it at 1500 ℃ for 3 hours, and cool it to room temperature. The bulk density of the breathable layer is greater than 3.0 g / cm³. 3 High-temperature flexural strength ≥20 MPa, high-temperature compressive strength ≥75 MPa, apparent porosity 20-40%, average pore width range 1-100 μm, and air permeability 0.1-2 μm. 2 .

[0009] With the above structure, the truncated cone-shaped brick core body has a permeable layer and an impermeable layer inside. The permeable layer is truncated cone-shaped and its cavity contains an impermeable layer. This type of permeable layer reduces the permeable area and improves the permeability uniformity of the permeable brick. At the same time, it accelerates the desorption speed of the initial bubbles and reduces the size of the initial bubbles. This is beneficial for capturing and removing fine inclusions in molten steel. Moreover, its structure is simple and easy to implement, which helps to reduce the cost of use and production. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the overall structure of the present invention; Figure 3 This is a practical application diagram of the invention installed in a steel ladle; In the diagram: 1. Frustum-shaped brick core body; 2. Air-permeable layer; 3. Impermeable layer; 4. Air chamber; 5. Ventilation channel; 6. Steel ladle shell; 7. Lining refractory material; 8. Magnetic permeable layer; 9. Slag line working layer. Detailed Implementation

[0011] like Figures 1 to 3 As shown, a steel ladle bottom-blown argon permeable brick includes a frustum-shaped brick core body 1. The upper part of the frustum-shaped brick core body 1 is provided with a permeable layer 2 and an impermeable layer 3 from the outside to the inside. The permeable layer 2 is a frustum shape with an open top and has a frustum-shaped cavity inside. The impermeable layer 3 fills the cavity. The lower part of the frustum-shaped brick core body 1 is also provided with a chamber 4 connected to the permeable layer 2. The chamber 4 is also frustum-shaped. The outer diameter of the bottom of the permeable layer 2 is greater than the inner diameter of the upper opening of the chamber 4. The bottom of the chamber 4 is connected to the upper end of the ventilation channel 5. The lower end of the ventilation channel 5 extends from the bottom of the frustum-shaped brick core body 1.

[0012] Because the permeable layer 2 has an internal cavity, and the cavity contains an impermeable layer 3, the permeable area of ​​the permeable layer 2 is reduced, thus improving the permeability uniformity of the permeable brick. At the same time, it accelerates the desorption rate of the initial bubbles and reduces the initial bubble size, which is beneficial for capturing and removing fine inclusions in the molten steel, and helps reduce usage and production costs. In addition, it reduces the spontaneous aggregation of bubbles in the bubble plume generated by the permeable brick, increases the spatial distribution area of ​​the bubbles, strengthens the stirring of the molten steel, and reduces the rising speed of the bubble plume, reducing the impact on the slag layer. This can reduce the slag hole area and the probability of slag entrapment, which is beneficial for improving the quality of the molten steel.

[0013] The height of the breathable layer 2 shall not be less than the height of the impermeable layer 3. Figure 2 The height of the impermeable layer 3 shown is less than the height of the permeable layer 2, but they can also be equal. In this case, the cross-section of the permeable layer 2 is annular, which further reduces the permeable area of ​​the permeable layer and improves the permeability uniformity of the permeable brick.

[0014] The impermeable layer is mainly composed of aggregate, matrix powder, and binder, with a mass ratio of 65-70:30-35:3.5-5. The main raw materials for the aggregate are high-purity tabular corundum, spinel, and mullite, with the high-purity tabular corundum having a particle size range of 1.0-1.5 mm, and the spinel and mullite having a particle size range of 1.25-1.5 mm. The matrix powder consists of calcined corundum powder and flaky corundum powder, with particle sizes less than 0.045 mm and 0.088 mm, respectively. The binder is a 15-20% concentration dextrin solution. In the fabrication of the impermeable layer 3, calcined corundum powder and flaky corundum powder are first introduced into a ball mill jar at a 1:1 mass ratio and premixed for 3-5 hours at 200 rpm. Then, aggregate, matrix powder, and binder are introduced into a mixer and mixed for 5-10 minutes. The mixture is then isostatically pressed under a pressure of 100-150 MPa. Finally, the formed impermeable layer is placed in a drying oven and kept at 110 °C for 24 hours, then fired at 1650 °C for 3 hours, and cooled to room temperature. The final impermeable layer has a bulk density greater than 3.2 g / cm³. 3 High-temperature flexural strength ≥40MPa, high-temperature compressive strength ≥100MPa, apparent porosity ≤5%.

[0015] The permeable layer is mainly composed of aggregate, matrix powder, and binder, with a mass ratio of aggregate to matrix powder to binder of 80-90:10-20. The main raw material for the aggregate is high-purity tabular corundum, with a particle size range of 0.25-0.5 mm. The matrix powder consists of calcined corundum powder and flaky corundum powder, with particle sizes less than 0.045 mm and 0.088 mm, respectively. The binder is a 15-20% concentration maltose solution, with a raw material to binder mass ratio of 100:5-7.5. The manufacturing process of the permeable layer is as follows: First, calcined corundum powder and flaky corundum powder are introduced into a ball mill jar at a 1:1 mass ratio and premixed for 3-5 hours at 200 rpm. Then, aggregates, powders, and binders are introduced into a mixer and mixed for 5-10 minutes. Next, the mixed raw materials are poured into a mold containing the impermeable layer and isostatically pressed under a pressure of 75-100 MPa. Finally, the molded permeable layer is placed in a drying oven and kept at 110°C for 24 hours, then fired at 1500°C for 3 hours, and cooled to room temperature. The final permeable layer has a bulk density greater than 3.0 g / cm³. 3 High-temperature flexural strength ≥20 MPa, high-temperature compressive strength ≥75 MPa, apparent porosity 25-40%, average pore width range 1-80 μm, and air permeability 0.8-2 μm. 2 .

[0016] When this permeable brick was applied to the refining ladle in the metallurgical field, with an argon blowing rate of 120 L / min and an argon blowing refining time of 30 min for a 150t ladle, the slag porosity of the ladle was 733.89 cm². 2 The average size of inclusions in the steel is 23.12 μm, and the slag hole area and the average size of inclusions in the steel are reduced by 19.26% and 24.21% respectively compared with traditional permeable bricks.

[0017] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A bottom-blown argon-permeable brick from a steel ladle, comprising a frustum-shaped brick core body, characterized in that: The upper interior of the frustum-shaped brick core body is provided with a breathable layer and an impermeable layer from the outside to the inside. The breathable layer is a frustum shape with an open top and has a frustum-shaped cavity inside. The impermeable layer fills the cavity. The lower interior of the frustum-shaped brick core body is also provided with an air chamber connected to the breathable layer. The bottom of the air chamber is connected to the upper end of the ventilation channel, and the lower end of the ventilation channel extends from the bottom of the frustum-shaped brick core body. The airtight layer is made of aggregate, matrix powder and binder, with the mass ratio of aggregate, matrix powder and binder being 65~70:30~35:3.5~5; The aggregate of the impermeable layer includes high-purity tabular corundum, spinel, and mullite. The particle size of the high-purity tabular corundum ranges from 1.0 to 1.5 mm, and the particle size ranges of the spinel and mullite ranges from 1.25 to 1.5 mm. The matrix powder of the impermeable layer is calcined corundum powder and flaky corundum powder, with particle sizes less than 0.045 mm and 0.088 mm, respectively. The binder of the impermeable layer is a 15-20% concentration dextrin solution. The processing of this airtight layer includes the following steps: S1. Add calcined corundum powder and flake corundum powder to a ball mill jar at a mass ratio of 1:1 and premix for 3-5 hours at a speed of 200 rpm; S2. Add aggregate, matrix powder and binder into a mixer and mix for 5-10 min. Use isostatic pressing process under a pressure of 100-150 MPa. S3. Finally, place the formed airtight layer in a drying oven at 110 ℃ and let it stand for 24 hours. Then, heat it at 1650 ℃ for 3 hours and cool it to room temperature.

2. The bottom-blown argon permeable brick of a steel ladle according to claim 1, characterized in that: The height of the breathable layer is not less than the height of the impermeable layer.

3. The bottom-blown argon permeable brick of a steel ladle according to claim 2, characterized in that: The air chamber is truncated cone-shaped, and the outer diameter of the bottom of the permeable layer is greater than the inner diameter of the opening at the top of the air chamber.

4. The bottom-blown argon permeable brick of a steel ladle according to claim 1, characterized in that: The air-impermeable layer has a bulk density greater than 3.2 g / cm 3 , high-temperature flexural strength ≥ 40 Mpa, high-temperature compressive strength ≥ 100 Mpa, and apparent porosity ≤ 5%.

5. The bottom-blown argon permeable brick of a steel ladle according to claim 1, characterized in that: The breathable layer is made of aggregate, matrix powder and binder, with the mass ratio of aggregate, matrix powder and binder being 75~90:10~25:5~10.

6. The bottom-blown argon permeable brick of a steel ladle according to claim 5, characterized in that: The aggregate of the permeable layer includes high-purity tabular corundum with a particle size range of 0.1~0.5 mm; the matrix powder of the permeable layer is calcined corundum powder and flaky corundum powder with particle sizes less than 0.045 mm and 0.088 mm, respectively; the binder of the permeable layer is a 10~25% concentration maltose solution. The processing of this breathable layer includes the following steps: S1. Add calcined corundum powder and flake corundum powder to a ball mill jar at a mass ratio of 1:1 and premix at 200 rpm for 3-5 hours. Then add aggregate, matrix powder and binder to a mixer and mix for 5-10 minutes. S2. Pour the mixed raw materials into a mold with an airtight layer, and use an isostatic pressing process under a pressure of 75~100 MPa. S3. Place the formed breathable layer in a drying oven at 110 ℃ and let it stand for 24 hours. Then, heat it at 1500 ℃ for 3 hours and cool it to room temperature.

7. A bottom-blown argon permeable brick for steel ladles according to claim 6, characterized in that: The bulk density of the breathable layer is greater than 3.0 g / cm³. 3 High-temperature flexural strength ≥20 MPa, high-temperature compressive strength ≥75 MPa, apparent porosity 20-40%, average pore width range 1-100 μm, and air permeability 0.1-2 μm. 2 .

Images