Aluminum silicon carbide carbon baking-free brick as well as preparation method and application thereof

Abstract

The invention relates to the field of material preparation, in particular to an aluminum silicon carbide carbon baking-free brick and a preparation method and application thereof. The aluminum silicon carbide carbon baking-free brick comprises the following components in parts by mass: 0-30 parts of compact corundum, 40-65 parts of silicon carbide, 0.5-2 parts of an antioxidant, 10-15 parts of a carbon raw material and 3-5 parts of composite resin, the carbon raw materials comprise crystalline flake graphite, spherical asphalt and carbon black. The aluminum silicon carbide carbon baking-free brick provided by the invention can effectively solve the problem of serious oxidation erosion of a refractory material at the slag line part of hot slag mineral wool electric furnace, has good comprehensive properties such as heat-conducting property, oxidation resistance and erosion resistance, improves the use effect and prolongs the service life.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and in particular to an aluminum silicon carbide carbon unfired brick and a preparation method and application thereof. Background Art

[0002] Building energy consumption accounts for a significant proportion of total energy consumption, and energy-saving and environmentally friendly requirements for rock wool production are constantly increasing. Currently, efforts are underway to improve wastewater treatment equipment and convert cupolas to electric furnaces to increase the concentration of the rock wool industry. Steel slag and blast furnace slag are the largest solid metallurgical slag emissions from the steel industry. Hot slag recycling technology is now mature and can be used to directly produce high-quality insulation materials. This new hot slag technology surpasses cold installation in many aspects, including comprehensive energy, environmental protection, land use, and investment. Using slag to melt slag to produce slag wool reduces energy consumption and costs.

[0003] As hot slag recycling technology matures, higher requirements are placed on furnace lining refractories. Since hot slag lining refractories operate at temperatures between 1400 and 1500°C, and the liquid slag is a waste product from smelting and other processes, precise control of its composition as a key parameter is difficult to achieve in order to produce a high-quality primary product. This necessitates rigorous compositional adjustments during the rock wool production process to ensure that the desired process parameters and product performance are met. The hot slag, when poured into the tempering furnace, reaches temperatures exceeding 1350°C. During use, it is subject to the oxidizing atmosphere and high-temperature molten metal, severely corroding the refractory. Current furnace lining solutions using high-alumina bricks and mullite bricks suffer from unstable material life at the slag line, with service lives of less than three months. Unfired aluminum-carbon bricks, a carbon-bonded material with superior oxidation resistance to magnesium-carbon bricks, are widely used in hot metal pretreatment equipment. Condensing furnace linings also effectively utilize the refractory's high thermal conductivity to keep the refractory surface temperature well below the reaction temperature of the hot slag liquid. Aluminum-carbon bricks are an excellent material for upgrading blast furnace linings. Their performance outperforms traditional refractory bricks for blast furnace linings and is similar to that of silicon nitride-bonded silicon carbide bricks, while significantly reducing costs. Because silicon carbide and graphite are ridged materials, the production of shaped products presents challenges such as difficulty in forming, low strength, and susceptibility to cracking. Consequently, the silicon carbide content of commercially available aluminum-silicon-carbide-carbon unfired bricks is generally below 15%, and the carbon content is below 10%. Given this, and addressing the slag line conditions in hot slag furnaces, there is an urgent need to provide a new type of aluminum-silicon-carbide-carbon unfired brick and its preparation method to extend the service life of aluminum-carbon bricks. Summary of the Invention

[0004] To address the above technical issues, the present invention provides an aluminum silicon carbide carbon unfired brick and a method for preparing the same. The aluminum silicon carbide carbon unfired brick provided by the present invention can effectively address the problems of severe oxidative corrosion and short service life of refractory materials in the slag line of hot slag mineral wool electric furnaces. It exhibits excellent thermal conductivity, resistance to oxidative corrosion, and other comprehensive properties, improving performance and extending service life.

[0005] In its first aspect, the present invention provides an aluminum silicon carbide carbon unfired brick comprising, by weight, 0-30 parts dense corundum, 40-65 parts silicon carbide, 0.5-2 parts antioxidant, 10-15 parts carbon raw material, and 3-5 parts composite resin; the carbon raw material includes flake graphite, spherical pitch, and carbon black. By optimizing the components of the aluminum silicon carbide carbon unfired brick and utilizing specific qualities of dense corundum, silicon carbide, carbon raw material, antioxidant, and composite resin, the present invention effectively addresses technical challenges such as oxidative corrosion of refractory materials in the slag line of hot slag mineral wool electric furnaces and short service life. The aluminum silicon carbide carbon unfired brick provided by the present invention exhibits high silicon carbide, high carbon content, high strength, and high thermal conductivity. Furthermore, it features a dense structure, low porosity, and excellent resistance to oxidative corrosion, extending its service life to over one year.

[0006] Preferably, the aluminum silicon carbide carbon unfired brick comprises, by weight, 10-28 parts of dense corundum, 45-65 parts of silicon carbide, 0.5-2 parts of antioxidant, 10-15 parts of carbon raw material, and 3-5 parts of composite resin. Preferably, the composition comprises 14-24 parts of dense corundum, 60-65 parts of silicon carbide, 1.5-2 parts of antioxidant, 10-15 parts of carbon raw material, and 3-4 parts of composite resin. This preferred ratio can further improve comprehensive properties such as thermal conductivity, resistance to oxidative corrosion, and mechanical properties, thereby extending the service life of the aluminum silicon carbide carbon unfired brick.

[0007] Further preferably, the carbon raw material is a composite powder of flake graphite, carbon black and spherical pitch; the mass ratio of flake graphite, carbon black and spherical pitch is 2~10:1~2:1~2, preferably 3~6:1~2:1~2; the carbon content of the carbon raw material is preferably 95%~99%, and the particle size is 7~1500 mesh.

[0008] In the present invention, flake graphite is used as a skeleton, and fine carbon black powder is introduced as a pore filling agent. Spherical pitch enhances viscosity and molding performance, preventing cracking during the molding process of aluminum-carbon bricks and low erosion resistance, which leads to slag leakage during the use of the material. Graphite has excellent thermal conductivity and refractory properties, a high melting point, a low thermal expansion coefficient, a high thermal conductivity coefficient, and good resistance to rapid cooling and heating. It has no eutectic relationship with alumina, silicon carbide, and silicon dioxide. It has a relatively large wetting angle for slag, which can prevent the slag from penetrating into the product. At the same time, the chemical reaction of carbon reducing the iron oxide in the slag to metal makes the slag highly viscous, which can reduce the migration of slag components into the brick, thereby achieving the effect of reducing erosion. In particular, by optimizing the ratio of flake graphite: carbon black: spherical pitch, and adding a certain mass amount to the blank, the synergistic effect between the components can be better exerted, and the overall performance is better.

[0009] Further preferably, the antioxidant is an ultrafine powder of metal aluminum powder, metal silicon powder, silicon nitride powder and boron nitride powder; the mass ratio of the metal aluminum powder, metal silicon powder, silicon nitride powder and boron nitride powder is preferably 1-4:1-4:1-2:1, more preferably 2-4:2-4:1-2:1, and the particle size is 200-1500 mesh. In the present invention, ultrafine powders including but not limited to metal aluminum powder, metal silicon powder, silicon nitride and boron nitride have a particle size of no more than 1500 mesh and a mass total amount of 0.5-2% in the blank, which has better antioxidant properties and overcomes the problem that most antioxidants on the market use 200 mesh metal aluminum powder and metal silicon powder with limited antioxidant properties. Of course, the use of antioxidants of other compositions is also within the scope of protection of the present invention. The present invention uses a composite of ultrafine powders of antioxidants of a specific composition, especially metal aluminum powder, metal silicon powder, silicon nitride and boron nitride in a preferred ratio, to make the blank have better antioxidant properties and interact with other components to further improve the overall performance.

[0010] Preferably, the silicon carbide content of the silicon carbide is preferably 90-99%, and the particle size is 200-1000 mesh. The silicon carbide mass content of the present invention is 40%-65%, which is a high silicon carbide aluminum-carbon brick. The silicon carbide used can prevent the oxidation of graphite and other carbon raw materials. In addition, silicon carbide itself is a very good refractory material with the characteristics of high temperature resistance and good chemical stability. Its thermal conductivity is higher than that of alumina, and its thermal expansion coefficient is only about half that of alumina. Silicon carbide also has strong erosion resistance, is not easily wetted by metal melt, and resists metal vapor erosion, which can increase the resistance to spalling and erosion by molten iron slag.

[0011] Preferably, the dense corundum has an alumina content of 97-99% and a particle size of 6-14 meshes.

[0012] Preferably, the composite resin is a phenolic resin and a silicone resin in a mass ratio of 1-5:1-5.

[0013] More preferably, the mass ratio of the phenolic resin to the silicone resin is 1-2:1-2, preferably 1:1. In the present invention, the combination of the phenolic resin and the silicone resin in a certain ratio, and the interaction with other components such as the preferred dense corundum, can better balance the properties of high-temperature adhesion, high-temperature stability, and strength, and the preferred ratio has a better effect.

[0014] Further preferably, the aluminum silicon carbide carbon unfired brick comprises the following components by weight: 10% to 30% dense corundum, 40% to 65% silicon carbide, 0.5% to 2% antioxidant, 10% to 15% carbon raw material, and 3% to 5% composite resin; the carbon raw material is preferably a composite powder of flake graphite, carbon black, and spherical pitch; the composite resin is preferably a phenolic resin and a silicone resin; and the antioxidant is preferably an ultrafine powder of metallic aluminum powder, metallic silicon powder, silicon nitride powder, and boron nitride powder. In the present invention, the optimized raw material ratios improve the overall mechanical properties, resistance to oxidative erosion, and corrosion resistance of the brick, better ensure the stability of the brick, extend the service life of the aluminum silicon carbide carbon unfired brick, and make it suitable for long-term use in harsh working environments. It is particularly suitable for high-temperature furnace linings, hot slag mineral wool electric furnace slag lines, and high-temperature refractory materials.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned aluminum silicon carbide carbon unfired brick, comprising: mixing and stirring silicon carbide, dense corundum and composite resin, and then adding silicon carbide, carbon raw material and antioxidant and mixing and stirring to obtain aluminum carbon brick blank; pressing and forming the aluminum carbon brick blank and drying it to obtain aluminum silicon carbide carbon unfired brick.

[0016] Preferably, the pressure of the press molding is 500-800T, preferably using a press to strike, and the number of strikes is 10-20 times; preferably, the pressure of the press molding is 600-650T, for example, 610, 615, 620, 625, 630, 635, 640T, etc., and the number of strikes is preferably 10-15 times, for example, 10, 11, 12, 13, 14 times; in the present invention, based on the interaction of each component, by optimizing the preparation process and conditions, it is possible to further improve the density, resistance to high-temperature oxidation and corrosion, optimize thermal stability, and reduce defects such as pores and cracks. In a preferred embodiment, the weight of the mud material is evenly distributed, a press of 630±5T is selected, and the press is controlled to strike 12 times, preferably 2 light hammers, 10 heavy hammers, and 2 exhausts.

[0017] More preferably, the drying temperature is 175-225°C, preferably 180-220°C, for example, 180, 185, 190, 195, 200, 205, 210, 215°C, and the drying time is 10-15 hours, for example, 11, 11.5, 12, 12.5, 13, 14, 15 hours. Drying ensures better brick formation and prevents cracking or deformation caused by internal moisture. Under the optimal pressing and drying temperature and time conditions, the density, mechanical properties, and other comprehensive properties of the aluminum carbide silicon carbon unfired brick can be further improved.

[0018] In a third aspect, the present invention provides applications of the aluminum silicon carbide carbon unfired bricks or the aluminum silicon carbide carbon unfired bricks obtained by the above preparation method, especially applications as refractory materials in the slag line of hot slag mineral wool electric furnaces.

[0019] The beneficial effects of the present invention are at least as follows: by optimizing the ratio and composition, the present invention can significantly improve the comprehensive performance of aluminum silicon carbide carbon unfired bricks, resulting in superior performance in terms of thermal conductivity, oxidation resistance, and corrosion resistance. The synergistic effect of the various components plays a crucial role in improving overall performance, significantly extending the service life while better solving the oxidation corrosion problems faced by traditional refractory materials. The invention is well-suited for use as refractory material in the slag line of hot slag mineral wool electric furnaces. The aluminum carbon bricks prepared by the present invention have good thermal conductivity, can reduce the surface temperature of the refractory material, significantly improve the oxidation corrosion resistance of the aluminum carbon bricks, and extend the service life of the aluminum carbon brick products to more than one year. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 These are the molding effect diagrams of aluminum-carbon bricks according to the embodiments of the present invention (ad are embodiments 1-4 respectively).

[0022] Figure 2 This is a diagram showing the anti-corrosion effects of the aluminum-carbon bricks according to an embodiment of the present invention and products on the market.

[0023] Figure 3 This is a diagram showing the induction anti-slag effect of the aluminum-carbon bricks according to the embodiment of the present invention and products on the market.

[0024] Figure 4 Schematic diagram of the actual use position of the aluminum-carbon brick provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0027] Where specific techniques or conditions are not specified in the examples of the present invention, the techniques or conditions described in the literature in the field or in the product specifications were followed. All devices, instruments, reagents, etc. used, where the manufacturer is not specified, are conventional products available through regular channels. All experimental reagents and raw materials involved are commercially available, and all reagents are analytically pure.

[0028] In the embodiments of the present invention, the dense corundum has an Al2O3 content of ≥99% and a particle size of 6-200 mesh. The silicon carbide (SiC) has an Al2O3 content of ≥97% and a particle size of 200-325 mesh. The flake graphite has a fixed carbon content of ≥90% and a particle size of 200-1500 mesh. The carbon black has a carbon content of ≥99% and a particle size of 100-325 mesh. The spherical pitch has a carbon content of ≥42% and a particle size of 7-100 mesh. The metallic aluminum powder has an Al2O3 content of ≥99% and a particle size of 200-1500 mesh. The metallic silicon powder has an Al2O3 content of ≥99% and a particle size of 200-1500 mesh. The metallic silicon powder has an SiO2 content of ≥99% and a particle size of 200-1500 mesh. The silicon nitride powder has an Si3N4 content of ≥99% and a particle size of 200-1500 mesh. The boron nitride powder has a boron content of ≥99% and a particle size of 200-1500 mesh. The phenolic resin has a solid content of ≥68%, and the silicone resin has a solid content of ≥50%.

[0029] Example 1 This embodiment provides an aluminum silicon carbide carbon unfired brick, which is composed of the following components by weight: 14 parts of dense corundum, 65 parts of silicon carbide, 2 parts of antioxidant, 15 parts of carbon raw material, and 4 parts of composite resin.

[0030] Among them, the silicon carbide content of the silicon carbide particles is 97%.

[0031] The carbon raw material is a composite powder of flake graphite, carbon black and spherical pitch (mass ratio 6:2:2) with a particle size of 7~1500 mesh.

[0032] The antioxidant is a mixed powder of metallic aluminum powder, metallic silicon powder, silicon nitride powder and boron nitride powder (mass ratio 4:2:1:1) with a particle size of 1500 mesh.

[0033] The composite resin is composed of phenolic resin and silicone resin (mass ratio 1:1).

[0034] This embodiment also provides a method for preparing the aluminum silicon carbide carbon unfired brick, the steps of which are as follows: Step 1: weigh silicon carbide particles and dense corundum particles.

[0035] Step 2: Mix the silicon carbide particles, dense corundum particles, and composite resin, and stir for 50 minutes.

[0036] Step 3: Release the evenly mixed particles from the mixer, clean the particles stuck to the side walls and gaps of the mixer, and then add the particles back into the mixer, add silicon carbide powder, carbon raw material, and antioxidant, and premix the powder for 50 minutes.

[0037] Step 4: Weigh a certain amount of mixed powder and put it into a 630T press, control the distribution of the mud material, press and exhaust well, and press the aluminum-carbon brick into shape.

[0038] Step 5: Place the pressed blank into a heating device for baking, first drying at 60°C for 24 hours and then drying at 220°C for 12 hours.

[0039] Example 2 This embodiment provides an aluminum silicon carbide carbon unfired brick and a preparation method, which is the same as the method in Example 1, except that it is composed of the following components: 24 parts of dense corundum, 60 parts of silicon carbide, 2 parts of antioxidant, 10 parts of carbon raw material, and 4 parts of composite resin.

[0040] Example 3 This embodiment provides an aluminum silicon carbide carbon unfired brick and a preparation method, which is the same as the method in Example 1, except that it is composed of the following components: 22 parts of dense corundum, 60 parts of silicon carbide, 2 parts of antioxidant, 12 parts of carbon raw material, and 4 parts of composite resin.

[0041] Example 4 This embodiment provides an aluminum silicon carbide carbon unfired brick and a preparation method, which is the same as the method in Example 1, except that it is composed of the following components: 19 parts of dense corundum, 60 parts of silicon carbide, 2 parts of antioxidant, 15 parts of carbon raw material, and 4 parts of composite resin.

[0042] Comparative Example 1 This comparative example provides an aluminum-carbon brick, which is a product on the market. Its main components are SiC≤10%, Al2O3≥65, and carbon content≤8%. The product is obtained by baking at 250°C.

[0043] Figure 1-Figure 3 The following chart compares the molding performance of the aluminum-carbon bricks of the examples and their erosion resistance and induction slag resistance with commercially available products. While Example 1 significantly improves bulk density, compressive strength, and apparent porosity compared to Comparative Example 1, the cracked aluminum-carbon bricks of Example 1 exhibit inferior erosion resistance compared to the other examples. The erosion resistance of the aluminum-carbon bricks of the other examples improves with increasing carbon raw material within a certain range (carbon content 10-15%).

[0044] Example 5 This embodiment provides an aluminum silicon carbide carbon unfired brick and a preparation method, which is the same as the method in Example 4, except that the carbon raw material is a composite powder of flake graphite, carbon black, and spherical asphalt (mass ratio 6:3:1) with a particle size of 7~1500 mesh.

[0045] Example 6 This embodiment provides an aluminum silicon carbide carbon unfired brick and a preparation method, which is the same as the method in Example 4, except that the antioxidant is a mixed powder of metal aluminum powder, metal silicon powder, silicon nitride powder, and boron nitride powder (mass ratio 4:4:1:1), with a particle size of 1500 mesh.

[0046] Example 7 This embodiment provides an aluminum silicon carbide carbon unfired brick and a preparation method thereof, which is the same as the method in Example 4, except that the composite resin is a composite of phenolic resin and silicone resin (mass ratio 1:2).

[0047] Performance tests were performed on the above examples and comparative examples in accordance with GB / T 2997-2015, Test method for bulk density, apparent porosity and true porosity of dense shaped refractory products; GB / T 5072-2023, Test method for compressive strength of refractory materials at room temperature; and GB / T 5990-2021, Test method for thermal conductivity, specific heat capacity and thermal diffusivity of refractory materials (hot wire method).

[0048] Figure 4 This is a schematic diagram of the actual use position of the aluminum-carbon bricks provided in the embodiment in a hot slag mineral wool electric furnace.

[0049] Table 1 Performance test results of the embodiments and comparative examples

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A kind of aluminum carbide silicon carbon unfired brick, characterized in that: The composition comprises, by mass, 0-30 parts of dense corundum, 40-65 parts of silicon carbide, 0.5-2 parts of antioxidant, 10-15 parts of carbon raw materials, and 3-5 parts of composite resin; the carbon raw materials include flake graphite, spherical pitch, and carbon black.

2. The aluminum silicon carbide carbon unfired brick according to claim 1, characterized in that: include: 10-28 parts of dense corundum, 45-65 parts of silicon carbide, 0.5-2 parts of antioxidant, 10-15 parts of carbon raw material, and 3-5 parts of composite resin.

3. The aluminum carbide silicon carbon unfired brick according to claim 1 or 2, characterized in that: The carbon raw material is a composite powder of flake graphite, carbon black, and spherical pitch; the mass ratio of the flake graphite, carbon black, and spherical pitch is 2-10:1-2:1-2, preferably 3-6:1-2:1-2; the carbon content of the carbon raw material is preferably 95%-99%.

4. The aluminum carbide silicon carbon unfired brick according to any one of claims 1 to 3, characterized in that: The antioxidant is ultrafine powder of metal aluminum powder, metal silicon powder, silicon nitride powder and boron nitride powder; the mass ratio of the metal aluminum powder, metal silicon powder, silicon nitride powder and boron nitride powder is selected to be 1~4:1~4:1~2:1, and the particle size is 200~1500 mesh.

5. The aluminum carbide silicon carbon unfired brick according to any one of claims 1 to 4, characterized in that: The composite resin is a phenolic resin and an organic silicon resin in a mass ratio of 1-5:1-5; the mass ratio of the phenolic resin and the organic silicon resin is preferably 1-2:1-2.

6. The aluminum carbide silicon carbon unfired brick according to any one of claims 1 to 5, characterized in that: The invention comprises the following components by mass content: 10% to 30% of dense corundum, 40% to 65% of silicon carbide, 0.5% to 2% of antioxidant, 10% to 15% of carbon raw material, and 3% to 5% of composite resin; the carbon raw material is preferably a composite powder of flake graphite, carbon black, and spherical asphalt; the composite resin is preferably a phenolic resin and an organic silicone resin; the antioxidant is preferably an ultrafine powder of metallic aluminum powder, metallic silicon powder, silicon nitride powder, and boron nitride powder.

7. The method for preparing the aluminum silicon carbide carbon unfired brick according to any one of claims 1 to 6, characterized in that: include: Silicon carbide, dense corundum and composite resin are mixed and stirred, and then silicon carbide, carbon raw material and antioxidant are added and mixed and stirred to obtain aluminum-carbon brick blank; The aluminum-carbon brick blank is pressed into shape and dried to obtain aluminum-silicon-carbide-carbon unfired bricks.

8. The preparation method according to claim 7, characterized in that The pressure of the compression molding is 500~800T, preferably using a press to hit, the number of hits is 10~20; Preferably, the pressing pressure is 600-650T, the number of blows is 10-15 times, preferably 1-4 times with a light hammer, 8-12 times with a heavy hammer, and 1-4 times with exhaust.

9. The preparation method according to claim 7 or 8, characterized in that The drying temperature is 175-225° C. and the drying time is 10-15 hours.

10. Use of the aluminum silicon carbide carbon unfired brick according to any one of claims 1 to 6 or the aluminum silicon carbide carbon unfired brick obtained by the preparation method according to any one of claims 7 to 9, characterized in that: Application of refractory materials in the slag line of hot slag mineral wool electric furnace.

Images