Composite ceramic refractory lining as well as preparation method and application thereof in blast furnace

Abstract

The invention relates to the technical field of high-temperature refractory materials, and discloses a composite ceramic refractory lining and a preparation method and application thereof in a blast furnace, the composite ceramic refractory lining is formed by compounding a corundum mullite material as a substrate and a zirconium ceramic material as a lining surface according to the mass percentage of 50%-85%: 50%-15%; wherein the corundum mullite material is prepared from the following raw materials in parts by mass: 40 to 50 parts of fused white corundum powder, 20 to 25 parts of alpha-Al2O3, 20 to 25 parts of gamma-Al2O3, 5 to 8 parts of kaolin and 1 to 2 parts of hydroxymethyl cellulose; the zirconium ceramic material comprises the following raw materials in parts by mass: 93-95 parts of fused zirconium powder, 2.5-3.5 parts of MgO powder, 1-2 parts of Y2O5 powder and 2-3 parts of hydroxymethyl cellulose. Compared with the existing corundum mullite lining, the refractory lining disclosed by the invention has the advantages that the high temperature resistance and high temperature corrosion resistance can be greatly improved, the softening temperature is increased, and the service life is greatly prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory materials, and in particular relates to a composite ceramic refractory lining, a preparation method thereof, and application in a blast furnace. Background Art

[0002] During ironmaking, the maximum temperature inside a blast furnace reaches 2000-2200°C, with the inner walls and bottom of the high-temperature section reaching temperatures as high as 1600-1800°C. The inner walls and bottom of the high-temperature section of blast furnaces in large steel mills, which come into direct contact with the molten iron, are generally lined with a high-temperature refractory corundum-mullite lining. This lining has a refractory temperature of 1700-1800°C and can operate at temperatures up to 1800°C, offering both high-temperature and high-temperature corrosion resistance. However, it begins to soften at 1770°C. Although corundum-mullite has a hardness greater than 8 on the Mohs scale, its hardness decreases significantly after entering the high-temperature softening stage. As molten iron and unmelted ore sink and fall, they rub against the corundum-mullite lining, causing some wear. As the operating temperature rises above the high-temperature softening temperature of the corundum-mullite lining, its hardness decreases, significantly increasing wear.

[0003] According to data from a certain ironworks, the average annual wear is approximately 30 mm, with an average annual wear rate exceeding 15%. The optimal service life of a corundum-mullite lining is only about three years. High-temperature zirconium ceramic linings have a Mohs hardness of 8.5-9, a melting temperature of 2715°C, a refractoriness of 2650°C, and a softening temperature above 2200°C. They can operate in ambient temperatures of 2000-2300°C for extended periods, and the 1800°C high temperatures of the furnace walls and bottom do not significantly affect their hardness. This significantly improves their high-temperature wear resistance, resulting in an average annual wear rate of less than 3%, extending their optimal service life to 8-10 years. However, the cost of high-temperature zirconium ceramic linings is significantly higher than that of corundum-mullite linings, at over five times the price. Furthermore, the production process requirements for high-temperature zirconium ceramic linings are quite demanding, so they are generally not accepted or used by manufacturers. Summary of the Invention

[0004] The present invention provides a composite ceramic refractory lining, a preparation method thereof and application in a blast furnace. Compared with the existing corundum-mullite lining, the composite ceramic refractory lining can greatly improve its high temperature resistance and high temperature corrosion resistance, increase the softening temperature and greatly extend the service life.

[0005] The technical solution of the present invention is to provide a composite ceramic refractory lining, which uses a corundum mullite material as a substrate and a zirconium ceramic material as a lining, and the two are composited in a mass percentage of 50% to 85%: 50% to 15%; The corundum mullite material comprises the following raw materials in parts by mass: fused white corundum powder 40-50 parts, alpha-Al2O3 20-25 parts, gamma-Al2O3 20-25 parts, kaolin 5-8 parts, and hydroxymethyl cellulose 1-2 parts; The zirconia ceramic material comprises the following raw materials in parts by mass: fused zirconium powder 93-95 parts, MgO powder 2.5-3.5 parts, Y2O5 powder 1-2 parts, and hydroxymethyl cellulose 2-3 parts.

[0006] Optionally, the mass ratio of the corundum mullite material to the zirconia ceramic material is 70-80%:30-20%.

[0007] Optionally, the raw materials in the corundum mullite material satisfy at least one of the following conditions: The content of Al2O3 in the fused white corundum powder is above 99 wt%, and the particle size is 250-325 mesh; The content of Al2O3 in the alpha-Al2O3 is above 90 wt%, and the particle size is 250-325 mesh; The content of Al2O3 in the gamma-Al2O3 is above 90 wt%, and the particle size is 250-325 mesh; The content of Al2O3 in the kaolin is 35-40 wt%, the content of SiO2 is 55-65 wt%, and the particle size is 250-325 mesh.

[0008] Optionally, the raw materials in the zirconia ceramic material satisfy at least one of the following conditions: The content of ZrO2 in the fused zirconium powder is above 99 wt%, and the particle size is 250-325 mesh; The content of MgO in the MgO powder is ≥99 wt%, and the particle size is 250-325 mesh; The content of Y2O5 in the Y2O5 powder is ≥99 wt%, and the particle size is 250-325 mesh.

[0009] Optionally, the hydroxymethyl cellulose in the zirconia ceramic material is sodium-free hydroxymethyl cellulose, and the content of Na is ≤0.2 wt%.

[0010] The application also relates to a preparation method of the composite ceramic refractory lining, comprising the following steps: S1, the raw materials of the corundum mullite material are put into a ball mill according to the proportion, water is added for ball milling, and then spray drying is performed to obtain particles, which are aged and stored for later use; S2, the raw materials of the zirconia ceramic material are put into a ball mill according to the proportion, water is added for ball milling, and then spray drying is performed to obtain particles, which are aged and stored for later use; S3, the corundum mullite particles are uniformly laid in a mold as a substrate, then grooves are raked on the upper part, the zirconia ceramic material is laid on the corundum mullite particles as a surface layer, and finally the mold is closed for isostatic pressing to form a brick body; S4. Dry the formed bricks and then put them into a firing kiln for firing.

[0011] Optionally, when ball milling in S1, the slurry fineness is 500-600 mesh and the specific gravity is 2.6-2.8; when ball milling in S2, the slurry fineness is 500-600 mesh and the specific gravity is 4.4-4.6; in S1 and S2, the moisture content of the spray-dried particles is 6-7%, and the particle size distribution is controlled at 15-20% below 40 mesh, 35-40% between 40-60 mesh, 30-35% between 60-80 mesh, and 10-15% above 80 mesh.

[0012] Optionally, the grooves are crisscrossed, the spacing between adjacent grooves is 40-60 mm, and the groove depth is 3-8 mm.

[0013] Optionally, the drying temperature is 100~200℃, and the drying is carried out until the moisture content is ≤0.5%; during firing, the temperature is first raised to 800℃ for 8~12 hours and kept warm for 3~5 hours; then the temperature is raised to 1050℃ for 8~10 hours, and then raised to 1150℃ for 10~13 hours, and finally raised to 1550℃ for 10~12 hours, and kept warm for more than 6 hours until firing; after firing, the temperature is lowered to 800℃ for 4~6 hours; then the temperature is lowered to 100℃ for 10~12 hours, and finally it is taken out of the kiln and naturally cooled to room temperature.

[0014] The invention also relates to the application of the refractory lining in a blast furnace.

[0015] The present invention has the following beneficial effects: 1. The present invention uses zirconium ceramic as the lining surface and corundum mullite as the substrate to produce a zirconium oxide-alumina high-temperature refractory ceramic composite material. This composite material fully utilizes the respective properties and advantages of corundum mullite and zirconium ceramic to replace the corundum mullite refractory lining. This composite material can effectively improve the high-temperature resistance, high-temperature corrosion resistance, and high-temperature wear resistance of the corundum mullite lining, thereby greatly extending the service life. It also alleviates the actual use pressure caused by the high cost of zirconium ceramic linings. It will become a development direction for product upgrading in this industry.

[0016] 2. The main component of corundum mullite is Al2O3, and the main component of zirconium ceramic is ZrO2. The expansion coefficient of Al2O3 is lower than that of ZrO2. Directly combining the two materials and firing them will affect the organic bonding between the corundum mullite and the zirconium ceramic due to the inconsistent expansion coefficients. In the present invention, fused white corundum powder is used as the main material in the corundum mullite, and a certain amount of α-Al2O3 and γ-Al2O3 is added to increase its expansion coefficient. Kaolin is also added to act as a binder, and a small amount of hydroxymethyl cellulose is added to act as a suspending and reinforcing agent. In the zirconium ceramic material, a small amount of MgO and Y2O5 is added to reduce the expansion coefficient of the entire material, while also improving the refractory temperature coefficient and increasing stability and strength.

[0017] 3、The application can make the combination of corundum mullite and zirconium ceramic more compact by setting the longitudinal and transverse interlaced grooves between them, and ensure the stability of the refractory lining under high temperature conditions.

[0018] 4、During the material firing, slow heating is needed when the temperature rises to about 800℃, and the temperature at 800℃ is kept for more than 4 hours to deal with the crystal transformation of the raw materials at this temperature section; the slow heating speed is controlled when the temperature rises to about 1100℃ to ensure the organic combination between corundum mullite and zirconium ceramic; the highest temperature firing section (1550℃) is kept for more than 6 hours to ensure that the porcelainization degree of the product meets the requirements, which is the key to ensure the hardness and strength index of the product; finally, slow cooling is carried out after the temperature drops to 800℃ to prevent unnecessary defects in the second crystal transformation. DETAILED DESCRIPTION

[0019] The experimental methods in the following examples are all conventional methods unless otherwise specified. The materials used in the following examples are all commercially available products unless otherwise specified.

[0020] The application provides a composite ceramic refractory lining, which is composed of corundum mullite material as a substrate and zirconium ceramic material as a surface, and the two are compounded in a mass percentage of 50%-85%:50%-15%; preferably 70-80%:30-30%; more preferably 75:25.

[0021] The corundum mullite material includes the following raw materials in parts by mass: 40-50 parts of fused white corundum powder, 20-25 parts of α-A12O3, 20-25 parts of γ-A12O3, 5-8 parts of kaolin, and 1-2 parts of hydroxymethyl cellulose. The zirconium ceramic material includes the following raw materials in parts by mass: 93-95 parts of fused zirconium powder, 2.5-3.5 parts of MgO powder, 1-2 parts of Y2O5 powder, and 2-3 parts of hydroxymethyl cellulose.

[0022] Specifically, the content of A12O3 in the fused white corundum powder is more than 99 wt%; the content of A12O3 in the α-A12O3 is more than 90 wt%; the content of A12O3 in the γ-A12O3 is more than 90 wt%; the content of A12O3 in the kaolin is 35-40 wt%, and the content of SiO2 is 55-65%.

[0023] Specifically, the raw materials in the zirconium ceramic material meet at least one of the following conditions: the content of ZrO2 in the fused zirconium powder is more than 99 wt%; the content of MgO in the MgO powder is ≥99 wt%; and the content of Y2O5 in the Y2O5 powder is ≥99 wt%.

[0024] In a preferred embodiment, the hydroxymethyl cellulose in the zircon ceramic material is sodium-free hydroxymethyl cellulose, and the Na content is ≤0.2wt%. By using sodium-free hydroxymethyl cellulose, the influence of impurity components on the refractory lining is avoided, and the refractoriness is reduced.

[0025] The application also provides a preparation process of the composite ceramic refractory lining, comprising the following steps: S1, the raw materials of the corundum mullite material are put into a ball mill according to the proportion, ball milling is performed after adding water, and then spray drying is performed to prepare particles, which are aged and reserved; S2, the raw materials of the zircon ceramic material are put into a ball mill according to the proportion, ball milling is performed after adding water, and then spray drying is performed to prepare particles, which are aged and reserved; S3, the corundum mullite particles are uniformly laid in a mold as a substrate, then grooves are raked on the upper part, the zircon ceramic material is laid on the corundum mullite particles as a surface layer, and finally the mold is closed for isostatic pressing to form a brick body; S4, the formed brick body is dried, and then is put into a sintering kiln for sintering, and the composite ceramic refractory lining is obtained.

[0026] In some embodiments, in S1, the slurry fineness is 500-600 mesh, and the specific gravity is 2.6-2.8; preferably, the slurry fineness is 600 mesh, and the specific gravity is 2.8; in S2, the slurry fineness is 500-600 mesh, and the specific gravity is 4.4-4.6; preferably, the slurry fineness is 600 mesh, and the specific gravity is 4.5.

[0027] In S1 and S2, the water content in the spray-dried particles is 6-7%, the particle size distribution is controlled to be 15-20% below 40 mesh, 35-40% between 40-60 mesh, 30-35% between 60-80 mesh, and 10-15% above 80 mesh.

[0028] In some embodiments, the grooves are longitudinally and transversely staggered, the distance between adjacent grooves is 40-60mm, and the groove depth is 3-8mm.

[0029] In some embodiments, the drying temperature is 100-200℃, and the drying is performed until the water content is ≤0.5%; during sintering, the temperature is first raised to 800℃ for 8-12h, and then kept for 3-5h; then the temperature is raised to 1050℃ for 8-10h, and then raised to 1150℃ for 10-13h, and finally raised to 1550℃ for 10-12h, and kept for more than 6h until sintering; after sintering, the temperature is reduced to 800℃ for 4-6h; then the temperature is reduced to 100℃ for 10-12h, and finally naturally cooled to room temperature.

[0030] The following further illustrates the application by combining specific embodiment cases.

[0031] Example 1 A composite ceramic refractory lining, which has corundum mullite material as a substrate and zircon ceramic material as a lining surface, both in a mass percentage of 75:25.

[0032] The corundum mullite raw material includes the following raw materials in mass parts: 45 parts of fused white corundum powder, 20 parts of α-A1203, 25 parts of γ-A1203, 8 parts of kaolin and 2 parts of hydroxymethyl cellulose.

[0033] The zircon ceramic material includes the following raw materials in mass parts: 94 parts of fused zirconium powder, 2.5 parts of MgO powder, 1.5 parts of Y2O5 powder and 2 parts of sodium-free hydroxymethyl cellulose.

[0034] The specific preparation steps are as follows: S1, the raw materials of the corundum mullite material are put into a ball mill according to the proportion, water is added for ball milling, and then spray drying is performed to prepare particles, which are aged and reserved; S2, the raw materials of the zircon ceramic material are put into a ball mill according to the proportion, water is added for ball milling, and then spray drying is performed to prepare particles, which are aged and reserved; S3, the corundum mullite particles are uniformly laid into a mold as a substrate, then grooves are raked on the upper part, and then the zircon ceramic material is laid on the corundum mullite particles as a surface layer, and finally the mold is closed for isostatic pressing to form a brick body; S4, the formed brick body is dried, and then enters a sintering kiln for sintering, preferably with the temperature rising to 800℃, 10h; 800℃ for 4h; then rising to 800-1050℃ for 8h; rising to 1050-1150℃ for 12h, and finally rising to 1150-1550℃ for 10h; 1550℃ for 6h or more until sintering. After sintering, first reduce the temperature to 800℃ for 5h; then reduce the temperature to 800-100℃ for 10h; after reaching 100℃, take out the kiln and cool to room temperature; thus the product is obtained.

[0035] Example 2: The same as example 1, except that the corundum mullite material includes the following raw materials in mass parts: 40 parts of fused white corundum powder, 25 parts of α-A1203, 25 parts of γ-A1203, 8 parts of kaolin and 2 parts of hydroxymethyl cellulose.

[0036] The zircon ceramic material includes the following raw materials in mass parts: 95 parts of fused zirconium powder, 2.5 parts of MgO powder, 1 part of Y2O5 powder and 2 parts of sodium-free hydroxymethyl cellulose.

[0037] Example 3: The same as example 1, except that the mass percentage of the corundum mullite material and the zircon ceramic material is 65:35.

[0038] The corundum mullite material comprises the following raw materials by mass parts: fused white corundum powder 50 parts, α-A1203 20 parts, γ-A1203 24 parts, kaolin 5 parts and hydroxymethyl cellulose 1 part.

[0039] The zirconia ceramic material comprises the following raw materials by mass parts: fused zirconium powder 93 parts, MgO powder 3 parts, Y2O5 powder 1.5 parts and sodium-free hydroxymethyl cellulose 2.5 parts.

[0040] Example 4: The same as Example 1, except that the mass percentage of the corundum mullite material to the zirconia ceramic material is 80:20.

[0041] The corundum mullite material comprises the following raw materials by mass parts: fused white corundum powder 48 parts, α-A1203 22 parts, γ-A1203 22 parts, kaolin 6 parts and hydroxymethyl cellulose 2 parts.

[0042] The zirconia ceramic material comprises the following raw materials by mass parts: fused zirconium powder 94 parts, MgO powder 3 parts, Y2O5 powder 1 part and sodium-free hydroxymethyl cellulose 2 parts.

[0043] Example 5 The same as Example 1, except that the content of hydroxymethyl cellulose Na in the zirconia ceramic material is 0.3wt%.

[0044] Comparative Example 1 The same as Example 1, except that no Y2O5 powder is added in the zirconia ceramic material.

[0045] Comparative Example 2 The same as Example 1, except that no MgO powder is added in the zirconia ceramic material.

[0046] Comparative Example 3 The same as Example 1, except that no Y2O5 powder and MgO powder are added in the zirconia ceramic material.

[0047] Comparative Example 4 The same as Example 1, except that the heating time at 1050-1150℃ in the firing temperature is 6h.

[0048] The refractory linings obtained in the above examples and comparative examples are subjected to performance tests, and the specific results are shown in Table 1.

[0049] The detection standards of the performance parameters are as follows: density GB / T2997-2015; refractoriness GB / T7320-2008; softening temperature GB / T 5989-2023; hardness GB / T 5072-2008; thermal expansion coefficient GB / T 7320-2018; and fracture toughness GB / T23806-2009.

[0050] Table 1

[0051] The above embodiments describe the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other manner, and these simple modifications and combinations should also be considered as disclosed by the present application and belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A composite ceramic refractory lining, characterized in that: It uses corundum mullite material as substrate and zirconium ceramic material as lining, and the two are composited in a mass percentage of 50%~85%:50%~15%; The corundum mullite material includes the following raw materials in parts by mass: 40-50 parts of fused white corundum powder, 20-25 parts of α-A12O3, 20-25 parts of γ-A12O3, 5-8 parts of kaolin and 1-2 parts of hydroxymethyl cellulose; The zirconium ceramic material includes the following raw materials in parts by mass: 93-95 parts of fused zirconium powder, 2.5-3.5 parts of MgO powder, 1-2 parts of Y2O5 powder and 2-3 parts of hydroxymethyl cellulose.

2. The composite ceramic refractory lining according to claim 1, characterized in that: The mass ratio of the corundum mullite material to the zirconium ceramic material is 70~80%:30~20%.

3. The composite ceramic refractory lining according to claim 1, characterized in that: The raw materials in the corundum mullite material meet at least one of the following conditions: The Al2O3 content in fused white corundum powder is above 99wt%; The content of A12O3 in α-A12O3 is above 90wt%; The content of A12O3 in γ-A12O3 is above 90wt%; The Al2O3 content in kaolin is 35~40wt%, and the SiO2 content is 55~65%; The particle size of the above raw materials is 250-325 mesh.

4. The composite ceramic refractory lining according to claim 1, characterized in that: The raw materials in the zirconium ceramic material meet at least one of the following conditions: The ZrO2 content in the fused zirconium powder is above 99 wt%; MgO content in MgO powder ≥99 wt%; Y2O5 powder Y2O5 content ≥99 wt %; The particle size of the above raw materials is 250-325 mesh.

5. The refractory lining according to any one of claims 1 to 4, characterized in that: The hydroxymethyl cellulose in the zirconium ceramic material is sodium-free hydroxymethyl cellulose, and its Na content is ≤0.2 wt%.

6. The method for preparing the composite ceramic refractory lining according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Put the raw materials of corundum mullite into a ball mill according to the proportion, add water to ball mill, and then spray dry to form particles, and then age them for later use; S2, putting the raw materials of zirconium ceramic material into a ball mill according to the proportion, adding water to ball mill, and then spray drying to form particles, and aging them for later use; S3, evenly spreading corundum mullite particles into the grinding tool as a backing, then raking grooves on the upper portion thereof, then spreading zirconium ceramic material on the corundum mullite particles as a surface layer, and finally closing the mold to perform isostatic pressing to form a brick body; S4. Dry the formed bricks and then put them into a firing kiln for firing.

7. The preparation method according to claim 6, characterized in that: When ball-milled in S1, the slurry fineness is 500-600 mesh and the specific gravity is 2.6-2.8; when ball-milled in S2, the slurry fineness is 500-600 mesh and the specific gravity is 4.4-4.6; in S1 and S2, the moisture content of the spray-dried particles is 6-7%, and the particle size distribution is controlled at 15-20% below 40 mesh, 35-40% between 40-60 mesh, 30-35% between 60-80 mesh, and 10-15% above 80 mesh.

8. The preparation method according to claim 6, characterized in that: The grooves are crisscrossed, the spacing between adjacent grooves is 40-60 mm, and the depth of the grooves is 3-8 mm.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The drying temperature is 100~200℃, and the moisture is dried to ≤0.5%; when firing, first heat it to 800℃ for 8~12 hours and keep it warm for 3~5 hours; then heat it to 1050℃ for 8~10 hours, then heat it to 1150℃ for 10~13 hours, and finally heat it to 1550℃ for 10~12 hours, and keep it warm for more than 6 hours until firing; after firing, cool it to 800℃ for 4~6 hours; then cool it to 100℃ for 10~12 hours, and finally cool it naturally to room temperature after taking it out of the kiln.

10. Use of the refractory lining according to any one of claims 1 to 5 or the refractory lining obtained by the preparation method according to any one of claims 6 to 9 in a blast furnace.

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