Low-cost environment-friendly carbon fire clay and preparation method thereof
A low-cost carbon-based refractory mud, made from white alumina and silicon carbide, addresses the high cost and environmental issues of traditional materials by enhancing mechanical properties and preventing steel leakage, thereby reducing production costs and environmental impact.
Patent Information
- Application Number
- CN202411682695.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-03-21
AI Technical Summary
The high cost and environmental hazards of traditional aluminum-magnesium-chromium refractory materials used in fireclay for filling gaps in steelmaking processes, combined with rising prices of materials like alumina, magnesia, and chromium oxide, lead to increased production costs and environmental concerns.
A low-cost carbon-based refractory mud composed of white alumina, silicon carbide, burnt magnesia, graphite, carbon black, silica powder, and colloidal silica, with a binder like ethylene glycol, which is mixed and processed to achieve enhanced mechanical properties and reduced environmental impact.
The new refractory mud significantly reduces production costs by up to 4000-5000 yuan per ton, extends the lifespan of intermediate packages, prevents steel leakage and corrosion, and eliminates the environmental hazards associated with chromium oxide, while maintaining excellent thermal and mechanical performance.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of refractory materials for steelmaking, and in particular relates to a low-cost carbon fire mud and a preparation method thereof. Background Art
[0002] The tundish is one of the main equipment in continuous casting. It mainly receives the molten steel from the melting furnace, and then controls the flow of the molten steel into the crystallizer through the tundish functional parts, so as to pull out the continuous casting billet smoothly and orderly. The slider tundish is a commonly used type of tundish. It mainly controls the amount of molten steel flowing into the crystallizer through the sizing upper water inlet and the slider, thereby controlling the pulling speed of the continuous casting billet.
[0003] Fire clay is used to fill the gaps between the water inlets and between the water inlets and the base bricks to avoid problems such as steel seepage, steel leakage and steel penetration, thereby ensuring the service life of the tundish. At present, the commonly used fire clay is aluminum-magnesium-chromium material fire clay, which is mainly composed of plate-shaped corundum, fused magnesia, and chromium oxide green fine powder. Although the use of the above materials is mature, these component materials are expensive. With the general trend of steel plant integration, the refractory market is highly competitive, and the contract price of refractory materials for the tundish continues to decline. In addition, the prices of refractory raw materials such as plate-shaped corundum, fused magnesia, and chromium oxide green continue to rise, with prices ranging from 8,000 to 9,000 yuan / ton. The increase in product costs has further compressed the profit margins of enterprises.
[0004] In addition, since chromium is toxic and polluting, chromium oxide green raw materials have serious impacts on the environment and organisms. Therefore, a low-cost and environmentally friendly fire clay is needed to fill the joints of the upper water inlet and the joints between the upper water inlet and the base bricks to reduce the company's refractory costs and environmental biological hazards. Summary of the invention
[0005] The purpose of the present invention is to provide a low-cost carbon fire clay and a preparation method thereof, using low-cost carbon raw materials and white corundum as main raw materials to replace aluminum-magnesium-chromium material fire clay, so as to achieve the purpose of reducing costs and increasing efficiency.
[0006] To achieve the above purpose, the technical solution of the present invention is as follows: A low-cost carbon fire clay, whose raw materials are calculated by weight percentage as follows: 40%-50% white corundum, 24%-35% silicon carbide, 5%-10% skin-burned magnesia, 3%-5% graphite, 1%-2% carbon black, 2%-4% fine powder silicon dioxide, 3%-5% talc powder as a sintering agent, and 2%-4% ethylene glycol as a binder; wherein the ethylene glycol as a binder is an added raw material.
[0007] Furthermore, the specifications of the raw materials in the low-cost carbon fire mud of the present invention are: white corundum ≤250 mesh, silicon carbide ≤320 mesh, skin-burned magnesia ≤200 mesh, graphite ≤200 mesh, silicon dioxide ≤1um, and talc ≤320 mesh.
[0008] Furthermore, the model of the carbon black in the low-cost carbon fire mud of the present invention is N220.
[0009] Furthermore, the preparation method of the low-cost carbon fire clay of the present invention is as follows: (1) accurately weighing white corundum, silicon carbide, burnt magnesia, graphite and carbon black according to a proportion and mixing them for 10-15 minutes to obtain a mixed powder; (2) premixing silicon dioxide, sintering agent talcum powder and binder ethylene glycol according to a proportion, and then adding them into a double cone mixer for mixing to obtain a premixed powder; (3) adding the premixed powder to the mixed powder, stirring and mixing for more than 15 minutes to obtain carbon fire clay.
[0010] Furthermore, the carbon fire mud of the present invention needs to be mixed with liquid water glass during use, and the weight ratio of carbon fire mud to liquid water glass is 1:0.15. Using liquid water glass instead of water to make fire mud can reduce the steel penetration of fire mud between the upper water inlet and the base brick.
[0011] Furthermore, the liquid water glass of the present invention has an appearance of a viscous liquid, is gray or gray-black, has a Baume degree Be≥50, a specific gravity≥1.5, and a modulus M≥2.5.
[0012] The inventive principle of the technical solution of the present invention is as follows: White corundum has high refractoriness, silicon carbide has good wear resistance and oxidation resistance; graphite and carbon black have relatively high residual carbon values and good resistance to slag infiltration; the introduction of skin-burned magnesia can react with corundum fine powder to form spinel, accompanied by 8% volume expansion, making the fire mud more dense in the gap, while magnesia and spinel also have high refractoriness and resistance to slag erosion; the introduction of silica fume can promote the sintering of mud. Talc is cheap and can improve the workability of mud when mixed at low temperature. Under high temperature conditions, it can promote sintering and generate high-temperature phases such as olivine.
[0013] Beneficial effects brought by the technical solution of the present invention: (1) The present invention adopts white corundum, silicon carbide, skin-burned magnesia, graphite, carbon black, fine powder and other raw materials to cooperate with each other. After the obtained carbon fire clay is calcined at 1500℃×3h, the room temperature flexural strength is above 10MPa; the room temperature flexural bonding strength is above 3MPa, and the line change rate after calcination is 0-0.5%.
[0014] (2) The carbon fire clay provided by the present invention has relatively good comprehensive performance. It can be used to fill the space between the upper water inlets and between the upper water inlet and the base bricks, which can meet the use effect and effectively avoid the problems of steel seepage, steel leakage and steel penetration in the tundish.
[0015] (3) The carbon fire clay provided by the present invention has a cost 4000-5000 yuan / ton lower than that of the traditional aluminum-magnesium-chromium material fire clay, which greatly reduces the production cost and improves the competitiveness of the product.
[0016] (4) The raw materials for preparing the carbon fire mud of the present invention eliminate the addition of chromium oxide green in the commonly used fire mud, thus avoiding the harm of the raw materials to the environment and organisms.
[0017] (5) The preparation method of the carbon fire mud of the present invention is relatively simple, easy to control, and can be mass-produced. DETAILED DESCRIPTION
[0018] The technical effects of the present invention are further described in detail below through embodiments. Examples 1-6
[0019] A low-cost carbon fire clay is prepared from white corundum, silicon carbide, skin-burned magnesia, graphite, carbon black, fine powder silicon dioxide, sintering agent talcum powder, and binder ethylene glycol; the preparation method is as follows: (1) accurately weighing and mixing white corundum, silicon carbide, burnt magnesia, graphite and carbon black according to the ratio for 10-15 minutes to obtain a mixed powder; (2) Premixing fine powdered silica, sintering agent talc and binder ethylene glycol according to a ratio, and then adding them into a double cone mixer for mixing to obtain a premixed powder; (3) Add the premixed powder into the mixed powder and stir for more than 15 minutes to obtain carbon fire mud.
[0020] The specifications and proportions of the raw materials in Examples 1-6 carbon fire mud are shown in Table 1.
[0021] Table 1 Specifications and ratios of raw materials in Examples 1-6 Carbon fire mud (%)
[0022] Comparative Example The cement of this comparative example is prepared from the following raw materials in percentage by weight: plate corundum 78%, alumina powder 5%, chrome green 2%, fused magnesia 6%, metallic aluminum powder 4%, clay 5%, and phenolic resin 3%.
[0023] The performance tests were carried out on the cements of various embodiments and comparative examples: after being calcined at 1500°C for 3h, the room-temperature flexural strength, room-temperature flexural bonding strength and post-calcination linear change rate were tested. The results are shown in Table 2.
[0024] Table 2 Carbon fire mud performance test results of each embodiment
[0025] The cements of various embodiments and comparative examples were used and compared in a steel plant in Hebei Province, and the service life and offline status of the tundish are shown in Table 3. The carbon fire mud of each embodiment was mixed with liquid water glass when used, and the weight ratio of carbon fire mud to liquid water glass was 1:0.15.
[0026] Table 3 Service life and offline status of tundish in various embodiments and comparative examples
[0027] It can be seen from Examples 1-6 and the comparative example that the fire clay of the comparative example was damaged and steel seeped in after 45 hours of use, posing a great safety hazard; while the fire clay provided by the present invention has a service life of more than 50 hours after use, the fire clay is intact, no cold steel penetrates from the joints between the upper water inlet of the tundish and the seat bricks, and there is no seamless steel seepage.
[0028] In summary, the present invention utilizes low-cost carbon raw materials and white corundum as main raw materials to replace aluminum-magnesium-chromium material fire clay, thereby reducing the enterprise's refractory cost, eliminating the phenomenon of steel seepage between the upper water inlets and between the upper water inlet and the seat bricks, meeting the on-site use requirements of the tundish, ensuring the service life of the tundish, and avoiding the harm of chromium oxide green to the environment and organisms.
Claims
1. A low-cost carbon fire mud, characterized in that: The raw materials are calculated by weight as follows: 40%-50% white corundum, 24%-35% silicon carbide, 5%-10% burnt magnesia, 3%-5% graphite, 1%-2% carbon black, 2%-4% fine powder silicon dioxide, 3%-5% talc powder as a sintering agent, and 2%-4% ethylene glycol as a binder; wherein the ethylene glycol as a binder is an external raw material.
2. A low-cost carbon fire mud according to claim 1, characterized in that: The specifications of the raw materials are: white corundum ≤250 mesh, silicon carbide ≤320 mesh, skin-burned magnesia ≤200 mesh, graphite ≤200 mesh, silicon dioxide ≤1um, talcum powder ≤320 mesh.
3. A low-cost carbon fire mud according to claim 1, characterized in that: The model of the carbon black is N220.
4. A low-cost carbon fire mud according to claim 1, characterized in that: The preparation method is as follows: (1) accurately weighing white corundum, silicon carbide, burnt magnesia, graphite and carbon black according to a proportion and mixing them for 10-15 minutes to obtain a mixed powder; (2) premixing silicon dioxide, sintering agent talcum powder and binder ethylene glycol according to a proportion, and then adding them into a double cone mixer for mixing to obtain a premixed powder; (3) adding the premixed powder into the mixed powder, stirring and mixing for more than 15 minutes to obtain carbon fire mud.
5. A low-cost carbon fire mud according to claim 1, characterized in that: The carbon fire mud needs to be mixed with liquid water glass during use, and the weight ratio of the carbon fire mud to the liquid water glass is 1:0.
15.
6. A low-cost carbon fire mud according to claim 1, characterized in that: After being calcined at 1500°C for 3h, the carbon fire clay has a room temperature flexural strength of more than 10MPa; a room temperature flexural bonding strength of more than 3MPa, and a line change rate of 0-0.5% after calcination.
7. The method for preparing low-cost carbon fire mud according to claim 1, characterized in that: The details are as follows: (1) accurately weigh white corundum, silicon carbide, burnt magnesia, graphite and carbon black according to the proportion and mix them for 10-15 minutes to obtain a mixed powder; (2) premix silica, sintering agent talcum powder and binder ethylene glycol according to the proportion, and then add them into a double cone mixer for mixing to obtain a premixed powder; (3) add the premixed powder to the mixed powder, stir and mix for more than 15 minutes to obtain carbon fire mud.