A pressurized mud for hot blast stove system repair, its preparation method and application

Abstract

This invention discloses a grouting material for repairing hot blast stove systems, its preparation method, and its application, belonging to the technical field of monolithic refractory materials. The grouting material comprises, by mass percentage: 35-50% lightweight mullite aggregate, 25-35% lightweight mullite powder, 8-14% α-Al₂O₃ micro powder, 2-4% microcrystalline wax, 7-10% quartz sand, 4-8% perlite particles, and 1-3% organic wax powder; plus 23-26% silica sol of the above components. The grouting material is prepared by first mixing the lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax, heating until the microcrystalline wax softens but does not melt, stirring evenly, and then adding the remaining raw materials and mixing evenly. This grouting material has the advantages of thermal insulation, high strength, and the construction time meets the grouting requirements. It can fully and densely fill gaps, block the thermal impact of hot airflow on the steel shell, and is suitable for grouting repair of hot blast stove bodies and piping systems.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a pressurized slurry for the repair of hot blast stove systems, its preparation method, and its application. Background Technology

[0002] Hot blast stoves are an important auxiliary component of blast furnace ironmaking, providing high-temperature hot air for blast furnace smelting, with blast temperatures reaching 1000–1300℃. With advancements in ironmaking technology, intensifying smelting and increasing blast temperature have become crucial technical means for cost reduction and efficiency improvement in the steel industry. Simultaneously, the blast stove lining is subjected to more demanding operating environments and higher heat loads. The periodic combustion and air supply of the hot blast stove cause the refractory lining inside the furnace to be subjected to rapid heating and cooling, resulting in cracking, shrinkage, and loosening. Excessive gaps and peeling of the upper brick lining of the pipes occur. High-temperature, high-pressure hot air erodes the steel shell through these gaps, causing the steel shell temperature to rise and turn red, necessitating grouting to seal the gaps or even shutting down the furnace for repairs, severely impacting normal blast furnace production.

[0003] Currently, hot blast stove repairs utilize grouting, requiring repair materials with excellent thermal insulation, high strength, erosion resistance, and filling properties. Resin-bonded grouts exhibit significant shrinkage at high temperatures, and their bond strength decreases considerably after medium-temperature carbonization, resulting in poor erosion resistance. Furthermore, organic binders contain numerous harmful substances, causing environmental pollution. Grouting materials using inorganic binders such as sols require large liquid additions, resulting in lower strength and greater shrinkage. When the material enters the high-temperature zone of the repair area, the sol gelation speed accelerates due to heat, and the binder is absorbed by the surrounding lining, leading to significant binder loss and increased grout viscosity. The material may lose its fluidity before even reaching the repair area. Increasing the binder addition to prolong the material's flow time can cause segregation, sedimentation, and pipe blockage, further reducing strength and increasing shrinkage, ultimately affecting the filling and repair effect. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a pressurized grout for the repair of hot blast stove systems, its preparation method, and its application. This pressurized grout has the advantages of heat insulation, high strength, and the construction time meets the grouting requirements. It can fully fill and compact the gaps, reduce the surface temperature of the steel shell, and ensure the normal operation of the hot blast stove and pipeline network.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A pressurized slurry for repairing a hot blast stove system is provided, comprising the following raw material components by mass percentage: 35-50% lightweight mullite aggregate, 25-35% lightweight mullite powder, 8-14% α-Al2O3 micro powder, 2-4% microcrystalline wax, 7-10% quartz sand, 4-8% perlite particles, and 1-3% organic wax powder; plus 23-26% silica sol by mass of the above components.

[0007] According to the above scheme, lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax are mixed beforehand and heated until the microcrystalline wax softens but does not melt, and then stirred evenly. Preferably, the temperature is heated to 63-65°C.

[0008] According to the above scheme, the particle size of the lightweight mullite aggregate is 0-1mm, and the particle size of the lightweight mullite powder is ≤0.074mm; wherein the Al2O3 content is ≥45%, and the Fe2O3 content is ≤0.5%.

[0009] According to the above scheme, the Al2O3 content of the α-Al2O3 micro powder is ≥99%, D 50 ≤1.5μm.

[0010] According to the above scheme, the quartz sand has SiO2 ≥ 99% and a particle size of ≤ 0.5~1mm.

[0011] According to the above scheme, the perlite has a particle size of 0.5-1 mm, an Al2O3 content of 10-18%, and a SiO2 content of 65-75%.

[0012] According to the above scheme, the microcrystalline wax is a white granular solid with a melting point of 68-70℃, an oil content of ≤2%, and a particle size of 3-5mm.

[0013] According to the above scheme, the organic wax powder is a modified urea resin, a white porous powder, which is an aggregate composed of nanoparticles, with a melting point of 155-160℃; preferably, the density is 1.47 g / cm³. 3 Specific surface area is 15-20 m² 2 / g, D50 is 3~6μm.

[0014] According to the above scheme, the specific gravity of the silica sol is 1.27-1.29, pH=7-9, and the average particle size is 10-20nm.

[0015] A method for preparing the above-mentioned pressurized mud for repairing hot blast stove systems is provided, comprising the following steps:

[0016] Lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax are mixed and heated to 63-65°C under high-speed stirring to soften the microcrystalline wax and mix it evenly with the solid particles. Then, the heating function is turned off, and α-Al2O3 micro powder, quartz sand, and organic wax powder are added. The mixture is stirred at low speed until all materials are evenly mixed and set aside. On-site, silica sol is added to obtain the pressurized slurry for the repair of hot blast stove systems.

[0017] According to the above method, heat to 63-65℃ under high-speed stirring, and then stir for 8-15 minutes.

[0018] According to the above scheme, the speed of high-speed stirring is 40-50 rpm.

[0019] According to the above scheme, the speed of low-speed stirring is 15-20 rpm.

[0020] This invention provides an application of the aforementioned pressurized mud in the pressurization and repair of the hot blast stove body and piping system.

[0021] This invention provides a pressurized slurry for repairing hot blast stove systems, employing two waxy agents in synergistic combination, wherein:

[0022] During the repair of the hot blast stove lining, the initial slurry, after being injected into the gaps, comes into contact with an ambient temperature exceeding 200°C. At this high temperature, both types of wax slowly decompose, forming micropores, which improves the slurry's heat insulation performance. Subsequent injections of slurry come into contact with a slightly lower ambient temperature. At this point, the waxes do not decompose and remain in a fluid liquid state, reducing the overall viscosity and increasing fluidity. As more slurry is injected, the contact temperature continues to decrease. The organic wax powder, with its high melting point, stops melting, while the microcrystalline wax, with its low melting point, continues to melt to maintain fluidity. The molten liquid wax is evenly distributed in the sol, slowing down the collision and polymerization rate of the sol particles, which also helps extend the flowability of the slurry and increases the construction time. In addition, when the slurry flows through the gap area, a small amount of binder is absorbed by the lining, and at the same time, the corresponding molten wax in the slurry migrates and covers the surface of the surrounding lining, preventing the binder from being further absorbed by the lining, extending the flow time of the slurry, and ensuring that the subsequent slurry can flow smoothly to the filling area, resulting in a significant filling and repair effect.

[0023] On the other hand, organic wax powder has a porous structure and good thermal insulation properties; at the same time, it has good suspension and dispersion properties, which can easily fill the pores formed by ultrafine powder (aluminum micro powder), so that the material reduces water while improving the thermal insulation performance of the mud at the microscopic level.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. This invention provides a pressurized grout for repairing hot blast stove systems. It employs a synergistic combination of microcrystalline wax and organic wax powder. Based on their different melting temperatures, this ensures good fluidity of the grout during construction. The molten liquid wax is evenly distributed in the sol, slowing down the collision and polymerization rate of sol particles and preventing further absorption of the binder by the lining, thus extending the grout's flowability time. Simultaneously, the organic wax powder itself is porous, providing good thermal insulation, and its nano-sized particles easily fill pores, further enhancing thermal insulation. Furthermore, the microcrystalline wax and organic wax powder decompose upon contact with high temperatures during the initial pressurized grouting stage, forming micropores, which also contributes to improved thermal insulation. The pressurized grout obtained by this invention, with its synergistic combination of components, possesses advantages such as thermal insulation, high strength, and strong resistance to erosion. The construction time meets the grouting requirements, effectively filling and compacting gaps, blocking the thermal impact of hot airflow on the steel shell, reducing the surface temperature of the steel shell, and ensuring the normal operation of the hot blast stove and pipeline network.

[0026] 2. This invention provides a method for preparing pressurized mud for the repair of hot blast stove systems. First, lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax are mixed and heated until the microcrystalline wax softens but does not melt. The mixture is then stirred evenly to uniformly coat the surface of the particles with a waxy film, effectively reducing the surface porosity of the mud. Simultaneously, the waxy film effectively prevents the binder from entering the voids within the particles, significantly reducing the amount of binder required, resulting in lower mud shrinkage and increased strength after hardening. Finally, other raw materials are added and mixed evenly. The preparation method is simple, the conditions are mild, and it is conducive to industrial application.

[0027] 3. In this invention, the microcrystalline wax is preheated to a softened but non-melting state, which ensures uniform coating of the granules while preventing the melted microcrystalline wax from entering the pores of the granules, thus reducing the amount of microcrystalline wax required and lowering the cost. It also avoids the negative effects associated with using large amounts of microcrystalline wax. Detailed Implementation

[0028] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0029] This invention provides a pressurized slurry for repairing hot blast stove systems, the raw material components of which are as follows by mass percentage:

[0030] Lightweight mullite aggregate 35-50%, lightweight mullite powder 25-35%, α-Al2O3 micro powder 8-14%, microcrystalline wax 2-4%, quartz sand 7-10%, perlite particles 4-8%, organic wax powder 1-3%; plus silica sol at 23-26% by weight of the above components.

[0031] The specific specifications of the raw materials used in the detailed implementation are as follows:

[0032] The particle size of the lightweight mullite aggregate is 0-1 mm, and the particle size of the lightweight mullite powder is ≤0.074 mm; the Al2O3 content is ≥45%, and the Fe2O3 content is ≤0.5%.

[0033] The Al2O3 content of α-Al2O3 micro powder is ≥99%, D 50 ≤1.5μm.

[0034] Quartz sand with SiO2 ≥ 99% and particle size ≤ 0.5~1mm.

[0035] The perlite has a particle size of 0.5–1 mm, with an Al2O3 content of 10–18% and a SiO2 content of 65–75%.

[0036] Microcrystalline wax is a white granular solid with a melting point of 68-70℃, an oil content of ≤2%, and a particle size of 3-5mm.

[0037] The organic wax powder is a modified urea resin, model SH-1089L. It is a white porous powder, an aggregate composed of nanoparticles, with a melting point of 155–160℃ and a density of 1.47 g / cm³. 3 Specific surface area is 15-20 m² 2 / g, D50 is 3~6μm.

[0038] The silica sol has a specific gravity of 1.27–1.29, a pH of 7–9, and an average particle size of 10–20 nm.

[0039] In a specific embodiment, the method for preparing the pressurized mud for repairing a hot blast stove system includes the following steps:

[0040] Lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax are added to a mixing mill. The mixing and heating function and high-speed mixing are turned on simultaneously. The temperature is heated to 63-65℃, and the mixing speed is 40-50 rpm, so that the microcrystalline wax is softened and evenly mixed with the solid particles. After mixing for 10 minutes, the heating function is turned off, and the remaining powder is added to the mixer. The mixing speed is turned on at low speed, 15-20 rpm. After all the materials are mixed evenly, they are bagged for later use. A silica sol binder is added at the construction site to obtain the pressurized mud for the repair of the hot air furnace system.

[0041] Example 1

[0042] A pressurized slurry for repairing a hot blast stove system is provided, comprising the following components by mass percentage: 35% lightweight mullite aggregate, 32% lightweight mullite powder, 12% α-Al2O3 micro powder, 2% microcrystalline wax, 10% quartz sand, 7% perlite particles, 2% organic wax powder, and 25.3% silica sol.

[0043] The pressurized slurry obtained in this embodiment, after testing, has a compressive strength of 10.5 MPa at 110°C, and a flowability time of 20–30 min at 110°C and 5–8 min at 180°C. It has a thermal conductivity of 0.35 W / mK, indicating good thermal insulation performance.

[0044] Comparative Example 1

[0045] A pressurized mud is provided, the components of which, by mass percentage, include: 35% lightweight mullite aggregate, 36% lightweight mullite powder, 12% α-Al2O3 micro powder, 10% quartz sand, 7% perlite particles, and 29.5% externally added silica sol.

[0046] After the materials were thoroughly mixed, a comparative material was obtained. Testing showed that the material had a compressive strength of 5.3 MPa at 110℃, and a flowable time of 5–10 minutes at 110℃ and 0.5–1 minute at 180℃. The thermal conductivity was 0.53 W / mK. It can be seen that increasing the amount of liquid added results in a shorter workable time and lower strength.

[0047] Example 2

[0048] A pressurized slurry for repairing a hot blast stove system is provided, comprising the following components by mass percentage: 39% lightweight mullite aggregate, 33% lightweight mullite powder, 10% α-Al2O3 micro powder, 4% microcrystalline wax, 7% quartz sand, 4% perlite particles, 3% organic wax powder, and 24.7% externally added silica sol.

[0049] The pressurized slurry obtained in this embodiment, after testing, has a compressive strength of 11.3 MPa at 110°C, and a flowability time of 20–30 min at 110°C and 5–8 min at 180°C. It has a thermal conductivity of 0.36 W / mK, indicating good thermal insulation performance.

[0050] Example 3

[0051] A pressurized slurry for repairing a hot blast stove system is provided, comprising the following components by mass percentage: 48% lightweight mullite aggregate, 27% lightweight mullite powder, 8% α-Al2O3 micro powder, 3% microcrystalline wax, 8% quartz sand, 5% perlite particles, 1% organic wax powder, and 25.7% externally added silica sol.

[0052] The pressurized slurry obtained in this embodiment, after testing, has a compressive strength of 10.8 MPa at 110°C, and a flowability time of 20–30 min at 110°C and 5–8 min at 180°C. It has a thermal conductivity of 0.38 W / mK, indicating good thermal insulation performance.

[0053] Example 4

[0054] A pressurized slurry for repairing a hot blast stove system is provided, comprising the following components by mass percentage: 37% lightweight mullite aggregate, 35% lightweight mullite powder, 14% α-Al2O3 micro powder, 2% microcrystalline wax, 7% quartz sand, 4% perlite particles, 1% organic wax powder, and 23.6% silica sol.

[0055] The pressurized slurry obtained in this embodiment, after testing, has a compressive strength of 12.5 MPa at 110°C, and a flowability time of 20–30 min at 110°C and 5–8 min at 180°C. It has a thermal conductivity of 0.38 W / mK, indicating good thermal insulation performance.

[0056] Example 5

[0057] A pressurized slurry for repairing a hot blast stove system is provided, comprising the following components by mass percentage: 43% lightweight mullite aggregate, 25% lightweight mullite powder, 10% α-Al2O3 micro powder, 3% microcrystalline wax, 9% quartz sand, 8% perlite particles, 2% organic wax powder, and 25.4% externally added silica sol.

[0058] The pressurized slurry obtained in this embodiment, after testing, has a compressive strength of 10.2 MPa at 110°C, and a flowability time of 20–30 min at 110°C and 5–8 min at 180°C. It has a thermal conductivity of 0.33 W / mK, indicating good thermal insulation performance.

[0059] Obviously, the above embodiments are merely examples for clear illustration 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. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A tamping mortar for hot blast stove system repair, characterized in that, The raw material components of the pressure-in mud include, by mass percentage: lightweight mullite aggregate 35-50%, lightweight mullite powder 25-35%, α-Al2O3 micro powder 8-14%, microcrystalline wax 2-4%, quartz sand 7-10%, perlite particles 4-8%, and organic wax powder 1-3%; additionally, 23-26% of the mass of the above components is silicon sol; wherein: The microcrystalline wax has a melting point of 68-70℃; The organic wax powder is a porous powder composed of agglomerates of nanoparticles, and has a melting point of 155-160℃; The lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax are mixed in advance and heated to a state in which the microcrystalline wax is softened but not melted, and then stirred uniformly.

2. The press-in mud of claim 1, wherein, The lightweight mullite aggregate particle size is 0-1 mm, and the lightweight mullite powder particle size is ≤0.074 mm; wherein the Al2O3 content is ≥45%, and the Fe2O3 content is ≤0.5%; the Al2O3 content of the α-Al2O3 micro powder is ≥99%, and the D 50 ≤1.5 μm; the SiO2 content of the quartz sand is ≥99%, and the particle size is ≤0.5-1 mm; the particle size of the perlite is 0.5-1 mm, wherein the Al2O3 content is 10-18%, and the SiO2 content is 65-75%.

3. The press-in mud of claim 1, wherein, The microcrystalline wax is a white granular solid, has an oil content of ≤2%, and has a particle size of 3-5mm.

4. The press-in mud of claim 1, wherein, The organic wax powder is a modified urea resin.

5. The press-in mud of claim 4, wherein, The density of the organic wax powder is 1.47 g / cm 3 The specific surface area is 15-20 m 2 / g, and the D50 is 3-6 μm.

6. The press-in mud of claim 1, wherein, The silicon sol has a specific gravity of 1.27-1.29, a pH of 7-9, and an average particle size of 10-20nm.

7. A method of preparing a tamping mortar for the repair of hot blast stove systems as claimed in claim 1, characterized in that The method comprises the following steps: The lightweight mullite aggregate, lightweight mullite powder, perlite, and microcrystalline wax are mixed and heated to a temperature of 63-65℃ under high-speed stirring, so that the microcrystalline wax is softened and uniformly mixed with the solid particles; then the heating function is turned off, and the α-Al2O3 micro powder, quartz sand, and organic wax powder are added and stirred at low speed; after the materials are mixed and stirred uniformly, the mixture is reserved for use, and the silicon sol is added on site to obtain the pressure-in mud for hot blast stove system repair.

8. The preparation method according to claim 7, characterized in that, After heating to a temperature of 63-65℃ under high-speed stirring, the stirring is continued for 8-15min; the high-speed stirring speed is 40-50rpm; and the low-speed stirring speed is 15-20rpm.

9. Use of the pressure-in mud for hot blast stove system repair according to claim 1 in the pressure-in repair of a hot blast stove body or a pipe network system.