Hard press-in repair process for blast furnace lining

Abstract

The invention discloses a hard press-in repair process for a blast furnace lining. The hard press-in repair process comprises the following steps: S1, preparing a hard press-in material; s2, preparing a hardening agent solution; s3, selecting a weak part of the blast furnace lining to open a hole, welding a pressing short pipe at the hole of the furnace shell, mounting a ball valve and a quick connector, and connecting the hole with a press-in machine by using a pipeline; s4, conveying a hard press-in material to a press-in opening through hard press-in equipment, conveying a hardening agent solution to the press-in opening through a hardening agent pump, mixing the hardening agent solution with the hard press-in material, pressing the mixture into the furnace, expanding the hard press-in material between the furnace lining and the furnace burden, hardening the hard press-in material under the action of the furnace temperature and a hardening agent, and bonding the hard press-in material with the furnace shell lining into a whole, and hard press-in repair of the blast furnace lining is completed. By improving the hard press-in material, various high-performance components are organically combined, and the comprehensive performance of the hard press-in material is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace repair, and in particular to a hard press-in repair process for a blast furnace lining. Background Art

[0002] Improving the lifespan of blast furnaces has become a major focus in the current ironmaking industry. Large blast furnaces abroad can reach a lifetime of over 15 years. Blast furnace longevity depends on numerous factors, including design and manufacturing, the selection and formulation of refractory materials, construction, and post-construction smelting, operation, and maintenance. Experts generally agree that smelting technology and maintenance techniques each contribute 50% to extending blast furnace life, demonstrating the importance of blast furnace maintenance techniques.

[0003] Traditionally, blast furnace lining maintenance primarily involves shutting down the furnace for major overhauls, requiring a complete halt to production and complete replacement of the entire lining. While this approach can completely resolve lining damage, it suffers from significant drawbacks such as long downtime, high costs, and disruptions to production continuity, severely restricting the economic operation of the blast furnace. To address the drawbacks of traditional maintenance methods, hard press-in technology has emerged. This technology allows the blast furnace to be maintained in a hot state during its scheduled downtime, without shutting down the furnace. Repairs to the refractory lining can then be performed from the outside, allowing smelting to resume after scheduled repairs are complete. This method is simple, economical, and reliable, providing a new technical approach for extending the life of blast furnaces.

[0004] The hard press-in repair technology is to transport the hard press-in material to the weak parts of the blast furnace lining through a high-pressure conveying system, mix it with the hardener and press it into the furnace. The "baffle" effect of the charge is used to squeeze it from the inside, so that the hard press-in material expands between the lining and the charge, and quickly bonds to the furnace shell lining. It hardens quickly under the action of the furnace temperature and the hardener, repairing the corroded and fallen refractory lining.

[0005] In recent years, domestic research and application of this technology have also begun, but the results have been subpar. Existing hard press-in materials often excel in only a single area, failing to simultaneously meet multiple performance requirements, including high-temperature strength, thermal shock resistance, and chemical corrosion resistance. In the complex operating environment of a blast furnace, single-performance repair materials are prone to localized failure, resulting in suboptimal repair results.

[0006] Therefore, it is urgent to develop a hard press-in repair process suitable for the characteristics of my country's blast furnaces, to achieve a significant improvement in the comprehensive performance of the repair materials, and to provide effective technical support for the longevity of my country's blast furnaces. Summary of the Invention

[0007] Based on the problems existing in the background technology, the present invention provides a hard press-in repair process for the lining of a blast furnace. By optimizing the hard press-in material, the performance of the hard press-in material is comprehensively improved, providing an effective solution for extending the life of the blast furnace.

[0008] The present invention is implemented through the following technical solutions:

[0009] A hard press-in repair process for a blast furnace lining comprises the following steps:

[0010] S1. Preparation of hard indentation material;

[0011] S2. Prepare a hardener solution;

[0012] S3. Select a weak spot in the blast furnace lining and drill a hole. Weld a short compression pipe to the hole in the furnace shell. Install a ball valve and quick connector. Connect the hole to the press with a pipe.

[0013] S4. The hard pressing material is transported to the pressure inlet through the hard pressing equipment, and the hardener solution is also transported to the pressure inlet through the hardener pump. After being mixed with the hard pressing material, it is pressed into the furnace. The hard pressing material expands between the furnace lining and the charge, hardens under the action of the furnace temperature and the hardener, and bonds to the furnace shell lining to complete the hard pressing repair of the blast furnace lining.

[0014] Furthermore, the hard pressing material in step S1 includes the following components by weight: 30-40 parts of aluminum silicon carbide material, 6-10 parts of magnesium aluminum spinel, 10-15 parts of mullite powder, 3-6 parts of cordierite powder, 3-6 parts of plate-shaped corundum, 3-6 parts of silicon nitride powder, 5-8 parts of graphene-modified graphite, 2-5 parts of silicon carbide whiskers, 1-4 parts of metallic silicon powder, 2-5 parts of boron carbide, 1-3 parts of SiC-coated carbon fiber, 1-2 parts of calcium oxide, and 6-10 parts of phenolic resin.

[0015] Furthermore, the aluminum silicon carbide material is a composite refractory material with aluminum oxide as the main body and silicon carbide as the reinforcement phase; wherein the content of aluminum oxide is 80-90%, the content of silicon carbide is 8-18%, and the content of silicon dioxide is 2-5%.

[0016] Furthermore, the preparation method of the graphene-modified graphite is specifically as follows: preparing graphene oxide by the Hummers method, reducing the graphene oxide to graphene nanosheets by a hydrothermal reduction method, dispersing and attaching the graphene nanosheets to the surface of flake graphite by electrostatic self-assembly, and heat treating at a high temperature of 1800°C to obtain the graphene-modified graphite;

[0017] The amount of graphene nanosheets used is 2-4% of the weight of the flake graphite.

[0018] Furthermore, the preparation method of the SiC-coated carbon fiber is specifically as follows: the surface of the carbon fiber is cleaned and activated, and a SiC coating is deposited on the surface of the carbon fiber by chemical vapor deposition using SiCl4 and CH4 as precursors and reacting at 1000°C and 5kPa for 4 hours.

[0019] Furthermore, the SiC-coated carbon fiber has a fiber diameter of 5-15 μm, a fiber length of 3-6 mm, and a SiC coating thickness of 0.5-1 μm.

[0020] Furthermore, the specific operation of preparing the hardener solution in step S2 is: dissolving benzenesulfonic acid in pure water to prepare a hardener solution with a specific gravity of 1.18-1.22.

[0021] Furthermore, in step S4, the pressing pressure of the hard pressing material is 1.5-3 MPa, and the added amount of the hardener solution is 20-30% of the weight of the phenolic resin.

[0022] Furthermore, in step S4, the mixing time of the hard pressing material and the hardening agent solution at the pressing inlet is 5-15 seconds.

[0023] Furthermore, it is suitable for repairing the lining of the blast furnace body, furnace waist and furnace belly.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention improves the hard press-in material by organically combining multiple high-performance components, thereby significantly improving the comprehensive performance of the hard press-in material. Aluminum silicon carbide material is used as the main material, and its temperature resistance can reach 1600-1700℃, which fully meets the requirements of the extremely high temperature environment inside the blast furnace. Magnesium aluminum spinel and mullite powder provide the repair material with excellent resistance to chemical erosion, and can resist the corrosion of slag and molten iron for a long time. The low thermal expansion characteristics of cordierite powder ensure good thermal matching between the repair layer and the original furnace lining, which can effectively alleviate the thermal stress caused by temperature changes and reduce thermal shock damage to the material. Plate-shaped corundum not only significantly improves the wear resistance and erosion resistance of the material, but its flaky morphology can also effectively prevent the expansion of cracks, playing an important toughening role. The introduction of silicon nitride powder significantly improves the material's thermal shock resistance and high-temperature strength retention rate. Silicon nitride has excellent high-temperature mechanical properties and a low thermal expansion coefficient. At the same time, its good oxidation resistance and chemical stability enable the material to maintain stable performance in both high-temperature oxidizing and reducing atmospheres. Silicon carbide whiskers, as a one-dimensional nano-reinforcement phase, improve the material's fracture toughness. Metallic silicon powder, as an antioxidant, effectively blocks oxygen diffusion into the material at high temperatures, protecting the carbonaceous components from oxidation. Boron nitride, as a superhard material, significantly enhances the material's wear resistance and resistance to mechanical erosion.

[0026] 2. The hard indentation material of the present invention also introduces graphene-modified graphite. The modified layer formed by graphene nanosheets on the surface of the graphite matrix has ultra-high thermal conductivity and excellent mechanical properties, which significantly improves the comprehensive performance of the graphite material. The two-dimensional structure and perfect lattice of graphene provide an excellent heat conduction channel for the material, and its blocking effect on oxygen molecules significantly improves the oxidation resistance of graphite. The synergistic effect between graphene and the graphite matrix not only maintains the good high-temperature thermal conductivity and chemical stability of graphite, but also improves the mechanical properties of the material through the nanoscale enhancement effect. Another SiC-coated carbon fiber material, the fiber forms a three-dimensional network structure in the material matrix, and significantly improves the toughness and impact resistance of the material through mechanisms such as carbon fiber bridging and pull-out toughening, while the SiC coating gives the carbon fiber excellent oxidation resistance and high-temperature stability. The core-shell structure formed after SiC coating not only retains the mechanical properties of carbon fiber, but also solves the problem of easy oxidation of carbon fiber in a high-temperature oxidizing environment.

[0027] 3. The components of the hard indentation material used in the present invention exhibit excellent synergistic effects. The reasonable ratio of aluminosilicate aggregate and carbonaceous material realizes the organic unity of fire resistance and thermal conductivity. The introduction of multiple hard phases significantly improves the mechanical properties of the material while achieving synergistic enhancement through different reinforcement mechanisms. The combination of nano-reinforced phase and micron-reinforced phase realizes multi-scale enhancement, which comprehensively improves the material performance. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0029] In the examples and comparative examples of the present invention, the preparation methods of the graphene-modified graphite and SiC-coated carbon fibers used are as follows:

[0030] The preparation method of graphene-modified graphite is specifically as follows: graphene oxide is prepared by the Hummers method, the graphene oxide is reduced to graphene nanosheets by a hydrothermal reduction method, the graphene nanosheets (the amount is 3% of the weight of the flake graphite) are dispersed and attached to the surface of the flake graphite by electrostatic self-assembly, and the graphene is obtained by high-temperature heat treatment at 1800°C.

[0031] The SiC-coated carbon fiber preparation method involves cleaning and activating the carbon fiber surface, then depositing a SiC coating on the carbon fiber surface using chemical vapor deposition (CVD) with SiCl4 and CH4 as precursors at 1000°C and 5kPa for four hours. The resulting SiC-coated carbon fiber has a fiber diameter of 5-15μm, a fiber length of 3-6mm, and a SiC coating thickness of 0.5-1μm.

[0032] In the embodiments and comparative examples of the present invention, the aluminum silicon carbide material used is a composite refractory material with aluminum oxide as the main component and silicon carbide as the reinforcing phase; wherein the aluminum oxide content is 87%, the silicon carbide content is 10%, and the silicon dioxide content is 3%.

[0033] Example 1

[0034] A hard press-in repair process for a blast furnace lining comprises the following steps:

[0035] S1. Preparation of a hard indentation material comprising the following components, in parts by weight: 36 parts of aluminum silicon carbide material, 8 parts of magnesium aluminum spinel, 12 parts of mullite powder, 4 parts of cordierite powder, 5 parts of plate-shaped corundum, 4 parts of silicon nitride powder, 6 parts of graphene-modified graphite, 3 parts of silicon carbide whiskers, 2 parts of metallic silicon powder, 3 parts of boron carbide, 2 parts of SiC-coated carbon fiber, 1 part of calcium oxide, and 8 parts of phenolic resin;

[0036] S2. Preparation of a hardener solution: Dissolve benzenesulfonic acid in pure water to obtain a hardener solution having a specific gravity of 1.2;

[0037] S3. Select a weak spot in the blast furnace lining and drill a hole. Weld a short compression pipe to the hole in the furnace shell. Install a ball valve and quick connector. Connect the hole to the press with a pipe.

[0038] S4. The hard pressing material is delivered to the pressure inlet through the hard pressing equipment at a pressure of 2.0 MPa, and the hardener solution is also delivered to the pressure inlet through the hardener pump. The added amount of hardener solution is 25% of the weight of the phenolic resin. After mixing with the hard pressing material for 10 seconds, it is pressed into the furnace. The hard pressing material expands between the furnace lining and the charge, and is hardened in 60 minutes under the action of the furnace temperature and the hardener, and is bonded to the furnace shell lining to complete the hard pressing repair of the blast furnace lining.

[0039] Example 2

[0040] The repair process of this embodiment is the same as that of Example 1, but the formula composition of the hard press-in material is adjusted as follows: the following components are included by weight: 32 parts of aluminum silicon carbide material, 10 parts of magnesium aluminum spinel, 15 parts of mullite powder, 6 parts of cordierite powder, 6 parts of plate-shaped corundum, 6 parts of silicon nitride powder, 8 parts of graphene-modified graphite, 5 parts of silicon carbide whiskers, 4 parts of metallic silicon powder, 5 parts of boron carbide, 3 parts of SiC-coated carbon fiber, 2 parts of calcium oxide, and 10 parts of phenolic resin.

[0041] Comparative Example 1

[0042] The repair process of this comparative example is the same as that of Example 1, but the formula composition of the hard press-in material is adjusted as follows: in parts by weight, it includes the following components: 45 parts of aluminum silicon carbide material, 25 parts of graphite, 15 parts of silicon carbide, 8 parts of silicon powder, and 7 parts of phenolic resin.

[0043] Comparative Example 2

[0044] The repair process of this comparative example is the same as that of Example 1, but the graphene-modified graphite is replaced by ordinary flake graphite in the formula of the hard press-in material.

[0045] Comparative Example 3

[0046] The repair process of this comparative example is the same as that of Example 1, except that the SiC-coated carbon fiber is replaced with ordinary carbon fiber in the formulation of the hard press-in material.

[0047] Comparative Example 4

[0048] The repair process of this comparative example is the same as that of Example 1, except that the plate-shaped corundum is replaced with ordinary corundum in the formula of the hard pressing material.

[0049] Test example

[0050] 1. Physical properties testing

[0051] (1) Bulk density: GB / T 2997 standard was used for testing, and the test was conducted under reducing conditions of 110°C for 24 h and 1100°C for 3 h.

[0052] (2) Porosity: The test was carried out in accordance with GB / T 2997 standard. The test conditions were the same as those for bulk density, and were carried out in a reducing environment at 110°C for 24 h and 1100°C for 3 h, respectively.

[0053] (3) Compressive strength: According to GB / T 5072 standard, the test was conducted under the reducing conditions of 110℃×24h and 1100℃×3h.

[0054] (4) Flexural strength: tested according to GB / T 3001 at 1000°C for 1 hour.

[0055] 2. High temperature performance testing

[0056] (1) Thermal shock resistance: The effect of rapid temperature changes during actual blast furnace operation on the repair material was simulated by using a rapid cooling and heating cycle between 1100°C and room temperature.

[0057] (2) High temperature volume stability: It is carried out under high temperature conditions of 1400℃×5h and evaluated by measuring the linear change rate of the material.

[0058] 3. Anti-corrosion performance test

[0059] (1) Alkaline slag corrosion test: carried out at 1500℃×6h, the corrosion resistance of the material is evaluated by measuring the depth of corrosion.

[0060] (2) Alkali metal vapor corrosion test: carried out in a K2O vapor environment at 1200℃×10h, and evaluated by measuring the change in material weight.

[0061] (3) CO gas corrosion test: This test is carried out in a CO gas environment at 1000°C for 100 hours and is evaluated by measuring the weight change of the material.

[0062] The test results are shown in Table 1.

[0063] Table 1 Performance test results of hard indentation materials in Examples and Comparative Examples

[0064]

[0065] It can be seen from the results in Table 1 that the embodiment has significant improvements in various key performance indicators compared with the comparative example. These performance improvements are directly converted into improved repair effects and extended repair life, providing reliable technical guarantees for the long-life operation of blast furnaces.

[0066] Comparative Example 1 uses a traditional hard press-in material formula, which only contains basic components such as aluminum silicon carbide material, graphite, silicon carbide, silicon powder and phenolic resin, and does not include the reinforcing phase and modified components of the present invention; all indicators of the final performance test are lower than those in the embodiment, especially the thermal shock resistance, which can only withstand 10 cycles, indicating that the hard press-in material of Example 1 has serious deficiencies in temperature shock resistance; the corrosion resistance is also significantly worse than that in the embodiment. Comparative Example 1 mainly relies on the chemical inertness of aluminum oxide to resist corrosion. However, aluminum oxide will react with silicon dioxide in an alkaline slag environment to form low-melting-point calcium aluminate, and the depth of alkaline slag corrosion is further increased.

[0067] In Comparative Example 2, graphene-modified graphite was replaced with ordinary flake graphite. Compared with Example 1, its compressive strength and flexural strength decreased slightly, and its thermal shock resistance decreased to 28 cycles. It can be seen that graphene modification improves the mechanical properties and thermal shock resistance of the material, especially the thermal shock resistance. The modified layer formed by graphene nanosheets on the surface of flake graphite constructs a multi-level heat conduction channel. At the microscopic scale, the two-dimensional structure of graphene provides an efficient in-plane heat conduction path; at the mesoscopic scale, the overlapping network formed by van der Waals interactions between graphene nanosheets constructs a three-dimensional heat-conducting skeleton; at the macroscopic scale, the contact thermal resistance between modified graphite particles is significantly reduced. This multi-scale collaborative heat conduction network enables the material to quickly reach temperature equilibrium under thermal shock and reduce local thermal stress concentration.

[0068] In Comparative Example 3, the SiC-coated carbon fibers were replaced with ordinary carbon fibers. Although carbon fibers themselves possess excellent mechanical properties, they are susceptible to oxidation failure in high-temperature oxidative environments. The SiC coating effectively protects the carbon fibers from oxidative corrosion. The flexural strength of Comparative Example 3 dropped from 5.2 MPa to 4.1 MPa, primarily because the carbon fibers, without the SiC protection, partially oxidized during the high-temperature test, reducing their effective load-bearing cross-section.

[0069] In Comparative Example 4, tabular corundum was replaced with ordinary corundum. Tabular corundum has a flaky morphology, which can effectively block crack propagation and provide better toughening effects. Ordinary corundum is mostly granular, and its toughening effect is relatively limited. The flexural strength of Comparative Example 4 dropped from 5.2MPa to 4.5MPa, and the thermal shock resistance dropped from 38 times to 32 times, both reflecting the impact of the lack of a toughening mechanism. In terms of corrosion resistance, the directional arrangement of tabular corundum formed an obstruction effect on the diffusion of the corrosive medium. The maze-like channels formed by the tabular particles in the material significantly increased the diffusion path length of the corrosive medium. Therefore, the depth of alkaline slag corrosion in Comparative Example 4 increased.

[0070] Finally, it should be noted that the above-described embodiments merely represent several implementation methods of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made by a person skilled in the art without departing from the spirit of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention should be based on the appended claims.

Claims

1. A hard press-in repair process for blast furnace lining, characterized in that: The following steps are involved: S1. Preparation of hard indentation material; S2. Prepare a hardener solution; S3. Select a weak spot in the blast furnace lining and drill a hole. Weld a short compression pipe to the hole in the furnace shell. Install a ball valve and quick connector. Connect the hole to the press with a pipe. S4. The hard pressing material is transported to the pressure inlet through the hard pressing equipment, and the hardener solution is also transported to the pressure inlet through the hardener pump. After being mixed with the hard pressing material, it is pressed into the furnace. The hard pressing material expands between the furnace lining and the charge, hardens under the action of the furnace temperature and the hardener, and bonds to the furnace shell lining to complete the hard pressing repair of the blast furnace lining.

2. The repair process according to claim 1, characterized in that: The hard pressing material in step S1 includes the following components by weight: 30-40 parts of aluminum silicon carbide material, 6-10 parts of magnesium aluminum spinel, 10-15 parts of mullite powder, 3-6 parts of cordierite powder, 3-6 parts of plate-shaped corundum, 3-6 parts of silicon nitride powder, 5-8 parts of graphene-modified graphite, 2-5 parts of silicon carbide whiskers, 1-4 parts of metallic silicon powder, 2-5 parts of boron carbide, 1-3 parts of SiC-coated carbon fiber, 1-2 parts of calcium oxide, and 6-10 parts of phenolic resin.

3. The repair process according to claim 2, characterized in that: The aluminum silicon carbide material is a composite refractory material with aluminum oxide as the main component and silicon carbide as the reinforcement phase; wherein the content of aluminum oxide is 80-90%, the content of silicon carbide is 8-18%, and the content of silicon dioxide is 2-5%.

4. The repair process according to claim 2, characterized in that: The preparation method of the graphene-modified graphite is specifically as follows: preparing graphene oxide by the Hummers method, reducing the graphene oxide to graphene nanosheets by a hydrothermal reduction method, dispersing and attaching the graphene nanosheets to the surface of flake graphite by electrostatic self-assembly, and then heat treating at a high temperature of 1800°C to obtain the graphene-modified graphite; The amount of graphene nanosheets used is 2-4% of the weight of the flake graphite.

5. The repair process according to claim 2, characterized in that: The preparation method of the SiC-coated carbon fiber is specifically as follows: cleaning and activating the carbon fiber surface, using chemical vapor deposition, SiCl4 and CH4 as precursors, reacting at 1000°C and 5kPa for 4 hours, and depositing a SiC coating on the carbon fiber surface.

6. The repair process according to claim 5, characterized in that: The SiC-coated carbon fiber has a fiber diameter of 5-15 μm, a fiber length of 3-6 mm, and a SiC coating thickness of 0.5-1 μm.

7. The repair process according to claim 1, characterized in that: The specific operation of preparing the hardener solution in step S2 is: dissolving benzenesulfonic acid in pure water to prepare a hardener solution with a specific gravity of 1.18-1.

22.

8. The repair process according to claim 1, characterized in that: In step S4 , the pressing pressure of the hard pressing material is 1.5-3 MPa, and the amount of the hardener solution added is 20-30% of the weight of the phenolic resin.

9. The repair process according to claim 1, characterized in that: In step S4, the mixing time of the hard pressing material and the hardening agent solution at the pressing inlet is 5-15 seconds.

10. The repair process according to claim 1, characterized in that: Suitable for repairing the lining of blast furnace body, furnace waist and furnace belly.

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