Refractory ceramic matrix material for smelting furnace linings and method for the production thereof

Abstract

This invention provides a refractory ceramic matrix material for smelting furnace linings and its preparation method, belonging to the technical field of ceramic refractory materials. The material includes coated modified fused magnesia aggregate, ceramic sand aggregate, surface-coated magnesia fine powder, γ-phase alumina micropowder, aluminum dihydrogen phosphate solution, alkaline silica sol, pre-reacted spinel precursor, and zirconium boride micropowder. The coated modified fused magnesia aggregate is prepared by mixing fused magnesia, silicon carbide composite powder, chromium trioxide powder, and phenolic resin powder, followed by sintering. Silicon carbide powder and magnesia powder are mixed, and a silicon nitride layer is deposited on the particle surface to obtain silicon carbide composite powder. The surface-coated magnesia fine powder is magnesia fine powder with alumina coated on the particle surface. The pre-reacted spinel precursor is prepared by preparing a mixed salt solution of magnesium nitrate hexahydrate and aluminum nitrate nonahydrate with deionized water, reacting, aging, and heat-treating. The ceramic sand aggregate is made of zirconium oxide. The allocation and use of each layer achieves a balanced improvement in performance.

Description

Technical Field

[0001] This invention pertains to the field of ceramic refractory materials technology, specifically relating to a refractory ceramic matrix material for smelting furnace linings and its preparation method. Background Technology

[0002] In high-temperature industries such as metallurgy and chemical engineering, smelting furnaces are core equipment for melting, refining, and reacting materials, and their refractory linings are a crucial barrier to ensure the safe operation of the furnace. Smelting furnaces operate in extremely harsh environments, constantly exposed to temperatures above 1200℃, while also enduring high-speed erosion from molten metal and slag, chemical corrosion from acidic and alkaline slag, and severe temperature fluctuations caused by furnace start-up, shutdown, and material switching. This places extremely high demands on the high-temperature resistance, erosion resistance, thermal shock stability, and mechanical strength of the refractory materials. The material properties directly determine the furnace's service life, production continuity, and operational safety.

[0003] In the early stages, due to limitations in industrial scale and temperature requirements, linings were mostly made of natural clay bricks and silica bricks. These materials were inexpensive but had limited high-temperature resistance, easily softening and sintering in environments above 1400℃, and had weak resistance to slag erosion. This resulted in a furnace lifespan of only 3-6 months, requiring frequent shutdowns for maintenance, which severely restricted production efficiency. As steel and non-ferrous metal smelting shifted towards large-scale and high-purity production, artificially synthesized single ceramic refractory materials such as corundum bricks and silicon carbide bricks gradually replaced natural materials. Their high-temperature resistance has improved, and their erosion resistance has been significantly enhanced. However, they suffer from drawbacks such as a large coefficient of thermal expansion and poor thermal shock stability, making them prone to cracking and spalling under temperature fluctuations, increasing the risk of furnace leakage.

[0004] Entering the 21st century, high-temperature industries have placed increasingly higher demands on the energy efficiency and safety of smelting furnaces. The furnace volumes of large blast furnaces, electric arc furnaces, and flash furnaces for non-ferrous metals have continued to expand, smelting temperatures have further increased, and the flow rates of molten metal and slag have become faster and more chemically reactive, highlighting the performance limitations of traditional single-material ceramic refractory materials. Against this backdrop, refractory ceramic matrix materials have emerged. These materials use a ceramic phase as the matrix and introduce reinforcing phases such as carbon fibers and silicon carbide whiskers, achieving a synergistic improvement in both high-temperature resistance and corrosion resistance, becoming the mainstream choice for linings of modern high-end smelting furnaces. However, with the development of new technologies such as low-carbon metallurgy and special alloy smelting, and the increasing demands for continuity and stability in smelting processes, existing refractory ceramic matrix materials still face many unresolved performance issues. The core unresolved performance issues of refractory materials are concentrated in the following three aspects:

[0005] 1. Insufficient performance synergy and balance: Existing materials generally have the phenomenon of "one advantage and many weaknesses". For example, although corundum-silicon carbide composite ceramic matrix materials are resistant to high temperature and corrosion, their thermal shock stability is poor. Long-term temperature fluctuations can easily accumulate thermal stress and generate microcracks. Although carbon fiber-containing materials can improve thermal shock stability, the bonding strength between the reinforcing phase and the matrix is ​​insufficient, and the interface is prone to oxidation at high temperature, which leads to a sharp drop in the overall performance of the material. It cannot simultaneously adapt to the complex working conditions of high temperature, erosion and temperature fluctuation.

[0006] 2. Insufficient stability during long-term service: Some materials meet the performance standards in short-term high-temperature tests, but after long-term continuous service, they will experience a decrease in mechanical strength and a weakening of erosion resistance due to problems such as high-temperature sintering shrinkage and slow failure of reinforcing phases, resulting in premature damage to the lining and failure to meet the requirements of long-term operation of the smelting furnace.

[0007] 3. Weak resistance to concentrated local damage: There are local high-temperature zones and high-speed erosion zones inside the smelting furnace. The performance uniformity of existing materials is insufficient. Local excessive wear and cracking are prone to occur in these special areas, which become weak points for the safe operation of the furnace body. Frequent local repairs are required, which affects production efficiency. Summary of the Invention

[0008] To address the problems of insufficient performance synergy, inadequate long-term service stability, and weak resistance to localized concentrated damage in existing refractory materials used for smelting furnace linings, this invention provides a refractory ceramic matrix material for smelting furnace linings and its preparation method. Through modification of core components such as coated and modified fused magnesia aggregate, ceramic sand aggregate, surface-coated magnesia fine powder, and pre-reacted spinel precursor, and precise process control, a balanced improvement in high-temperature resistance, slag erosion resistance, thermal shock stability, mechanical strength, and structural density is achieved. This material can adapt to the complex operating conditions of smelting furnaces, including high temperature, high-speed erosion, severe temperature fluctuations, and acid-alkali slag erosion, thus extending the service life of the furnace lining. The specific technical solution is as follows:

[0009] A refractory ceramic matrix material for lining a smelting furnace comprises the following raw materials in parts by weight: 75-80 parts of coated modified fused magnesia main aggregate, 10-15 parts of ceramic sand main aggregate, 8-12 parts of surface-coated magnesia fine powder, 2-5 parts of γ-phase alumina micro powder, 3-5 parts of aluminum dihydrogen phosphate solution, 2-4 parts of alkaline silica sol, 3-5 parts of pre-reacted spinel precursor, and 0.5-1 part of zirconium boride micro powder;

[0010] The coated modified fused magnesia main aggregate is prepared by mixing fused magnesia, silicon carbide composite powder, chromium trioxide powder and phenolic resin powder in a mass ratio of 100:(6-8):(2-3):(5-7) and sintering; the silicon carbide composite powder is prepared by mixing silicon carbide powder and magnesium oxide powder in a mass ratio of (2-3):1 and depositing a silicon nitride layer on the particle surface.

[0011] The surface-coated magnesium oxide fine powder is magnesium oxide fine powder particles coated with aluminum oxide;

[0012] The pre-reacted spinel precursor is prepared by mixing magnesium nitrate hexahydrate and aluminum nitrate nonahydrate with deionized water to form a mixed salt solution, reacting at pH 9.0-9.5, aging, and heat treatment.

[0013] The main aggregate of the ceramic sand is made of zirconium oxide.

[0014] The preparation of the modified fused magnesia aggregate in the above materials includes: mixing silicon carbide powder and magnesium oxide powder at a mass ratio of (2-3):1, reacting them at 800℃-900℃ and 0.08MPa-0.1MPa with a nitrogen-silane mixed gas to form a silicon nitride layer, and obtaining silicon carbide composite powder; mixing the fused magnesia: silicon carbide composite powder: chromium trioxide powder: phenolic resin powder in a mass ratio of 100:(6-8):(2-3):(5-7), sintering, cooling, dispersing and grading, and grading to obtain the modified fused magnesia aggregate (using phenolic resin powder as a binder to coat the silicon carbide composite powder and chromium trioxide powder onto the particle surface of the fused magnesia aggregate).

[0015] In the preparation of the above-mentioned coated modified fused magnesia main aggregate, the median particle size of the silicon carbide powder and the magnesium oxide powder is 1μm to 5μm; the volume ratio of nitrogen to silane in the nitrogen-silane mixed gas is (92 to 95): (5 to 8); the magnesium oxide content of the fused magnesia is ≥95wt%; the median particle size of the chromium trioxide powder is 1μm to 5μm; the median particle size of the phenolic resin powder is 1μm to 3μm; the sintering is carried out at 500℃ to 600℃ for 1h to 2h; the particle size distribution of the coated modified fused magnesia main aggregate is: 3mm < particle size ≤ 5mm accounts for 20wt% to 25wt%, 1mm < particle size ≤ 3mm accounts for 25wt% to 30wt%, 0.5mm < particle size ≤ 1mm accounts for 15wt% to 20wt%, and particle size ≤ 0.5mm accounts for 10wt% to 15wt%.

[0016] The preparation of the surface-coated magnesium oxide fine powder in the above materials includes: continuously introducing triethylaluminum vapor into the magnesium oxide fine powder at 130℃~150℃ and 0.12MPa~0.15MPa, and then switching to water vapor to deposit an aluminum hydroxide layer on the surface of the magnesium oxide fine powder particles; holding the temperature at 800℃~850℃ for 1.5h~2.5h to convert the aluminum hydroxide layer into an aluminum oxide coating layer; and obtaining the surface-coated magnesium oxide fine powder after cooling.

[0017] In the preparation of the above-mentioned surface-coated magnesium oxide fine powder, the particle size range of the magnesium oxide fine powder is 0.1 mm to 0.5 mm; the introduction time of the triethylaluminum vapor is 30 min to 40 min; and the introduction time of the water vapor is 25 min to 35 min.

[0018] The preparation of the pre-reacted spinel precursor in the above materials includes: weighing two raw materials according to the mass ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate (1.2-1.3):4, preparing a mixed salt solution with 1.8-2.2 times the total mass of the raw materials in deionized water, adjusting the pH to 9.0-9.5 with ammonia, stirring, aging, filtering to separate the precipitate and mother liquor, washing the precipitate with deionized water and ethanol, drying to obtain the primary precursor; and subjecting the primary precursor to heat treatment to obtain the pre-reacted spinel precursor.

[0019] In the preparation of the above-mentioned pre-reacted spinel precursor, the heat treatment parameters are as follows: heating at 4℃ / min to 6℃ / min to 300℃ to 350℃, holding at that temperature for 1h to 1.5h, heating at 2℃ / min to 3℃ / min to 400℃ to 550℃, holding at that temperature for 1.5h to 2h, and then cooling to room temperature.

[0020] In the above materials, the particle size distribution of the main aggregate of ceramic sand is as follows: 0.6mm < particle size ≤ 0.85mm accounts for 45wt% to 50wt%, 0.425mm < particle size ≤ 0.6mm accounts for 30wt% to 35wt%, and 0.25mm < particle size ≤ 0.425mm accounts for 15wt% to 25wt%.

[0021] In the above materials, the median particle size of the γ-phase alumina micro powder is 1 μm to 5 μm.

[0022] In the above materials, the median particle size of the zirconium boride micro powder is 1 μm to 3 μm.

[0023] The preparation method of the above-mentioned refractory ceramic matrix material for lining a smelting furnace includes the following steps:

[0024] S1: According to the mass fractions, the coated modified fused magnesia main aggregate, ceramic sand main aggregate, surface-coated magnesia fine powder, γ-phase alumina micro powder, pre-reacted spinel precursor and zirconium boride micro powder are dry-mixed evenly to obtain a mixture; then aluminum dihydrogen phosphate solution, alkaline silica sol and water are added and wet-mixed evenly to obtain refractory ceramic matrix material.

[0025] S2: The furnace lining is rammed in layers, dried naturally, and then heated to cure, resulting in a furnace lining of refractory ceramic matrix material.

[0026] In step S1 of the above preparation method, the amount of water added is 5% to 7% of the mass of the mixture.

[0027] In step S2 of the above preparation method, the natural drying time is 24h to 30h; the parameters for the heating and curing are: heating at 8℃ / h to 10℃ / h to 200℃ to 250℃ and holding for 8h to 10h, heating at 10℃ / h to 15℃ / h to 600℃ to 700℃ and holding for 6h to 8h, heating at 10℃ / h to 15℃ / h to 1200℃ to 1300℃ and holding for 4h to 6h, followed by natural cooling.

[0028] The present invention provides a refractory ceramic matrix material for smelting furnace lining and its preparation method, the beneficial effects of which include:

[0029] I. The refractory ceramic matrix material for smelting furnace lining of this invention solves the pain points of traditional refractory materials, such as poor performance synergy, weak long-term stability, and insufficient resistance to local damage, through core component modification and precise process control. It achieves a balanced improvement in high temperature resistance, slag erosion resistance, thermal shock stability, mechanical strength, and structural density. It can adapt to the complex working conditions of smelting furnaces, such as high temperature, high speed erosion, severe temperature fluctuations, and acid and alkali slag erosion, extend the service life of the furnace lining, reduce the frequency of furnace shutdown for maintenance, and ensure production continuity and safety.

[0030] II. Coated and Modified Fused Magnesia Main Aggregate: Using phenolic resin powder as a binder, silicon carbide composite powder and chromium oxide powder are coated onto the surface of the fused magnesia main aggregate particles. The silicon carbide composite powder and chromium oxide are modified by depositing a silicon nitride layer on the surface. The silicon nitride layer can isolate oxygen and inhibit silicon carbide oxidation. Cr2O3 and MgO form a solid solution to strengthen the interfacial bonding, while improving high temperature resistance and corrosion resistance, providing a high-strength skeleton for the material.

[0031] III. Zirconia ceramic sand as main aggregate: The multi-gradation design fills the gaps in the modified fused magnesia sand, reducing porosity; the low thermal expansion characteristics of zirconia alleviate the thermal stress caused by temperature fluctuations and prevent material cracking.

[0032] IV. Surface Coating with Fine Magnesium Oxide Powder: The aluminum oxide coating improves the interfacial wettability between magnesium oxide and the substrate, blocks the reaction between magnesium oxide and moisture, avoids the formation of Mg(OH)2 decomposition and the generation of pores, and at the same time inhibits the high-temperature oxidation of magnesium oxide, thereby improving structural stability.

[0033] 5. Gamma-phase alumina micro powder: It forms a stable bonding network with aluminum dihydrogen phosphate and alkaline silica sol, filling tiny gaps, avoiding structural looseness caused by the decomposition of the bonding phase at high temperatures, and enhancing the overall density of the material.

[0034] VI. Pre-reacted spinel precursor: During sintering, MgAl2O4 spinel phase is generated in situ, forming a solid solution with magnesium oxide and aluminum oxide. This reduces the difference in thermal expansion coefficients between the phases to alleviate thermal stress. At the same time, the chemical inertness of spinel is used to suppress the Ca content in the slag. 2+ Fe 3+Diffusion enhances resistance to erosion.

[0035] VII. Zirconium boride micro powder: With its high hardness and chemical stability, it further enhances the material's resistance to high-speed erosion and slag corrosion, and strengthens the wear resistance of easily damaged areas.

[0036] 8. Composite bonding system of aluminum dihydrogen phosphate and alkaline silica sol: SiO2 reacts with Al2O3 to form a low-temperature eutectic phase, which improves the high-temperature bonding strength; at the same time, it inhibits the high-temperature decomposition of aluminum dihydrogen phosphate, avoids the formation of a large number of pores, and ensures the structural integrity of long-term service.

[0037] 9. Raw material gradation control: The specific gradation of modified fused magnesia and ceramic sand synergistically achieves the densest packing of coarse particle skeleton and fine particle filling, reducing material porosity and reducing the channels for slag penetration and abrasive cutting.

[0038] 10. Staged heating and curing: Low heating rate and multi-stage heat preservation (200℃~250℃, 600℃~700℃, 1200℃~1300℃) can achieve slow evaporation of moisture and gradual decomposition of organic matter, avoiding internal stress concentration and microcracks caused by rapid heating; at the same time, it promotes the full reaction of each component, spinel is generated in situ, solid solution is formed, and a uniform and stable microstructure is constructed.

[0039] XI. Synergistic effect of skeleton, bonding and function: Modified fused magnesia and zirconia ceramic sand form a high-strength skeleton, γ-phase alumina and composite cementing system form a dense bonding network, and pre-reacted spinel and zirconium boride play a functional strengthening role. The three work together to achieve simultaneous improvement in strength, density and corrosion resistance, avoiding the defects of "single advantage and multiple weaknesses" of a single component.

[0040] 12. Synergistic Interface Optimization: The silicon nitride layer of modified fused magnesia, the alumina coating layer of magnesia fine powder, and the solid solution interface of spinel work together to improve the interfacial wettability and bonding strength between the components, reduce interfacial oxidation, debonding or crack propagation at high temperatures, solve the problem of weak bonding between the reinforcing phase and the matrix, and improve long-term service stability.

[0041] Thirteen, Synergistic Thermal Stress Relief: The low expansion characteristics of zirconia, the control of the thermal expansion coefficient of spinel, and the release of internal stress through staged heating form a thermal stress relief system from the material itself to process control, avoiding cracking and spalling caused by temperature fluctuations and improving thermal shock stability; at the same time, combined with erosion-resistant zirconium boride and corrosion-resistant spinel, the material's ability to resist localized concentrated damage is enhanced, making it suitable for the stringent requirements of the local high temperature and high speed erosion zone of the smelting furnace. Detailed Implementation

[0042] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0043] Example 1

[0044] A refractory ceramic matrix material for lining a smelting furnace comprises the following raw materials in parts by weight: 78 parts of coated modified fused magnesia main aggregate, 12 parts of ceramic sand main aggregate, 10 parts of surface-coated magnesia fine powder, 3.5 parts of γ-phase alumina micro powder, 4 parts of aluminum dihydrogen phosphate solution, 3 parts of alkaline silica sol, 4 parts of pre-reacted spinel precursor, and 0.8 parts of zirconium boride micro powder.

[0045] The preparation of the coated modified fused magnesia main aggregate includes: mixing silicon carbide powder with a median particle size of 2.6 μm and magnesium oxide powder with a median particle size of 3.5 μm at a mass ratio of 2.5:1; under conditions of 850℃ and 0.09 MPa, introducing a nitrogen-silane mixed gas with a volume ratio of 93:7 at a gas flow rate of 18 L / h for 12 min, stopping the gas flow, and holding the reaction at the temperature for 45 min; repeating the gas flow-holding reaction cycle twice to form a silicon nitride layer; after stopping the gas flow, introducing argon gas at a flow rate of 6 L / h, and removing the material after it has naturally cooled to room temperature to obtain silicon carbide composite powder; the ratio of fused magnesia (magnesia content 96.5 wt%) to silicon carbide composite powder to trioxide is: Chromium oxide powder (median particle size 4.2 μm): phenolic resin powder (median particle size 2.3 μm) were mixed uniformly at a mass ratio of 100:7:2.5:6. The mixture was heated to 550℃ at a rate of 6℃ / min and sintered for 1.5 h. After cooling, the agglomerated powder was broken up, classified, and graded to obtain a coated modified fused magnesia aggregate with a particle size distribution of 30 wt% for particles 3 mm < ≤ 5 mm, 40 wt% for particles 1 mm < ≤ 3 mm, 20 wt% for particles 0.5 mm < ≤ 1 mm, and 10 wt% for particles ≤ 0.5 mm. (The silicon carbide composite powder and chromium oxide powder were coated onto the particle surface of the fused magnesia aggregate using phenolic resin powder as a binder.)

[0046] The preparation of surface-coated magnesium oxide fine powder includes: magnesium oxide fine powder with a particle size range of 0.1 mm to 0.5 mm, under the conditions of 140 °C and 0.13 MPa, triethylaluminum vapor is introduced at a flow rate of 12 L / h for 35 min, and then the flow rate is switched to water vapor at 10 L / h for 30 min, so that an aluminum hydroxide layer is deposited on the surface of the magnesium oxide fine powder particles; then the temperature is increased to 820 °C at 5 °C / min and held for 2 h, so that the aluminum hydroxide layer is transformed into a dense alumina coating layer, and after cooling, surface-coated magnesium oxide fine powder is obtained.

[0047] The preparation of the pre-reacted spinel precursor includes: weighing two raw materials at room temperature according to a mass ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate of 1.25:4, adding twice the total mass of deionized water, stirring at 280 r / min for 35 min to prepare a mixed salt solution, adjusting the pH to 9.2 with 5 wt% ammonia water under stirring at 350 r / min at 32℃, stirring at 230 r / min for 35 min, aging at room temperature for 12 h, and separating the precipitate and mother liquor by filtration. The precipitate was repeatedly washed with deionized water (each time using 1.8 times the mass of the precipitate, for a total of 5 washes; the absence of white precipitate was confirmed by testing with silver nitrate solution). Finally, it was washed once with ethanol equal to the mass of the precipitate. The precipitate was filtered until it was loose and dried at 100°C for 8 hours to obtain the primary precursor. The primary precursor was then subjected to heat treatment: the temperature was increased to 320°C at 5°C / min and held for 1 hour, then increased to 500°C at 2°C / min and held for 2 hours. The temperature was then cooled to room temperature to obtain the pre-reacted spinel precursor.

[0048] The ceramic sand aggregate has the following particle size distribution: 45 wt% for particles between 0.6 mm and 0.85 mm, 30 wt% for particles between 0.425 mm and 0.6 mm, and 25 wt% for particles between 0.25 mm and 0.425 mm. The median particle size of the γ-phase alumina powder is 3 μm. The effective content of the aluminum dihydrogen phosphate solution is 50%. The content of the alkaline silica sol is 50%. The median particle size of the zirconium boride powder is 2 μm.

[0049] The preparation method of the above-mentioned refractory ceramic matrix material for lining a smelting furnace includes the following steps:

[0050] According to the mass fractions, the coated modified fused magnesia main aggregate, ceramic sand main aggregate, surface-coated magnesia fine powder, γ-phase alumina micro powder, pre-reacted spinel precursor and zirconium boride micro powder are dry-mixed evenly to obtain a mixture; then aluminum dihydrogen phosphate solution, alkaline silica sol and water (the amount of water added is 6% of the mass of the mixture) are added in sequence and wet-mixed evenly to obtain a billet, that is, refractory ceramic matrix material;

[0051] The furnace lining is rammed in layers, with each layer not exceeding 100mm in thickness, and a construction bulk density of 2.8g / cm³. 3 ~3.0g / cm 3 The total thickness of the furnace lining is determined according to the actual furnace lining design. The furnace lining is then naturally dried (ambient temperature > 10℃) for 26 hours, heated to 220℃ at 9℃ / h and held for 9 hours, heated to 650℃ at 12℃ / h and held for 7 hours, heated to 1250℃ at 12℃ / h and held for 5 hours, and then naturally cooled to obtain the furnace lining of the refractory ceramic matrix material.

[0052] Example 2

[0053] A refractory ceramic matrix material for lining a smelting furnace comprises the following raw materials in parts by weight: 75 parts of coated modified fused magnesia main aggregate, 15 parts of ceramic sand main aggregate, 8 parts of surface-coated magnesia fine powder, 5 parts of γ-phase alumina micro powder, 3 parts of aluminum dihydrogen phosphate solution, 4 parts of alkaline silica sol, 3 parts of pre-reacted spinel precursor, and 0.5 parts of zirconium boride micro powder.

[0054] The preparation of the coated modified fused magnesia main aggregate includes: mixing silicon carbide powder with a median particle size of 5 μm and magnesium oxide powder with a median particle size of 1 μm at a mass ratio of 3:1; under conditions of 800℃ and 0.1 MPa, introducing a nitrogen-silane mixed gas with a volume ratio of 92:8 at a gas flow rate of 15 L / h for 15 min, then stopping the gas flow and maintaining the temperature for 40 min; repeating the gas flow-temperature reaction cycle three times to form a silicon nitride layer; after stopping the gas flow, introducing argon gas at a flow rate of 5 L / h, and removing the material after it has naturally cooled to room temperature to obtain silicon carbide composite powder; the ratio of fused magnesia (magnesia content 97.2 wt%) to silicon carbide composite powder is: Chromium trioxide powder (median particle size 5 μm): phenolic resin powder (median particle size 1 μm) = 100:8:2:7 were mixed evenly and heated to 600℃ at 5℃ / min, and sintered for 1 hour. After cooling, the agglomerated powder was broken up, classified, and graded to obtain a coated modified fused magnesia main aggregate with a particle size distribution of 3mm < particle size ≤ 5mm accounting for 35wt%, 1mm < particle size ≤ 3mm accounting for 35wt%, 0.5mm < particle size ≤ 1mm accounting for 15wt%, and particle size ≤ 0.5mm accounting for 15wt%. (The silicon carbide composite powder and chromium trioxide powder were coated on the particle surface of the fused magnesia main aggregate with phenolic resin powder as a binder.)

[0055] The preparation of the surface-coated magnesium oxide fine powder includes: magnesium oxide fine powder with a particle size range of 0.1 mm to 0.5 mm, under the conditions of 130 °C and 0.15 MPa, triethylaluminum vapor is introduced at a flow rate of 10 L / h for 40 min, and then the flow rate is switched to water vapor at 8 L / h for 35 min, so that an aluminum hydroxide layer is deposited on the surface of the magnesium oxide fine powder particles; then the temperature is increased to 850 °C at 4 °C / min and held for 1.5 h, so that the aluminum hydroxide layer is transformed into a dense alumina coating layer, and after cooling, the surface-coated magnesium oxide fine powder is obtained.

[0056] The preparation of the pre-reacted spinel precursor includes: weighing two raw materials at room temperature according to a mass ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate of 1.3:4, adding 1.8 times the total mass of deionized water, stirring at 300 r / min for 30 min to prepare a mixed salt solution, adjusting the pH to 9.0 with 6 wt% ammonia water under stirring at 300 r / min at 35℃, stirring at 250 r / min for 30 min, aging at room temperature for 14 h, and separating the precipitate and mother liquor by filtration. The precipitate was repeatedly washed with deionized water (each time using 1.5 times the mass of the precipitate, for a total of 6 washes; the absence of white precipitate was confirmed by testing with silver nitrate solution). Finally, it was washed twice with 0.8 times the mass of the precipitate in ethanol. The precipitate was filtered until it was loose and dried at 95°C for 9 hours to obtain the primary precursor. The primary precursor was then subjected to heat treatment: the temperature was increased to 350°C at 4°C / min and held for 1 hour, then increased to 400°C at 3°C / min and held for 2 hours. The temperature was then cooled to room temperature to obtain the pre-reacted spinel precursor.

[0057] The ceramic sand aggregate has the following particle size distribution: 50 wt% for particles between 0.6 mm and 0.85 mm, 35 wt% for particles between 0.425 mm and 0.6 mm, and 15 wt% for particles between 0.25 mm and 0.425 mm. The median particle size of the γ-phase alumina powder is 1 μm. The effective content of the aluminum dihydrogen phosphate solution is 50%. The content of the alkaline silica sol is 50%. The median particle size of the zirconium boride powder is 3 μm.

[0058] The preparation method of the above-mentioned refractory ceramic matrix material for lining a smelting furnace includes the following steps:

[0059] According to the mass fractions, the coated modified fused magnesia main aggregate, ceramic sand main aggregate, surface-coated magnesia fine powder, γ-phase alumina micro powder, pre-reacted spinel precursor and zirconium boride micro powder are dry-mixed evenly to obtain a mixture; then aluminum dihydrogen phosphate solution, alkaline silica sol and water (the amount of water added is 5% of the mass of the mixture) are added in sequence and wet-mixed evenly to obtain a billet, that is, refractory ceramic matrix material;

[0060] The furnace lining is rammed in layers, with each layer not exceeding 100mm in thickness, and a construction bulk density of 2.8g / cm³. 3 ~3.0g / cm 3 The total thickness of the furnace lining is determined according to the actual furnace lining design. The furnace lining is then naturally dried (ambient temperature > 10℃) for 30 hours, heated to 250℃ at 8℃ / h and held for 8 hours, heated to 600℃ at 15℃ / h and held for 8 hours, heated to 1300℃ at 10℃ / h and held for 4 hours, and then naturally cooled to obtain the furnace lining of refractory ceramic matrix material.

[0061] Example 3

[0062] A refractory ceramic matrix material for lining a smelting furnace comprises the following raw materials in parts by weight: 80 parts of coated modified fused magnesia main aggregate, 10 parts of ceramic sand main aggregate, 12 parts of surface-coated magnesia fine powder, 2 parts of γ-phase alumina micro powder, 5 parts of aluminum dihydrogen phosphate solution, 2 parts of alkaline silica sol, 5 parts of pre-reacted spinel precursor, and 1 part of zirconium boride micro powder.

[0063] The preparation of the coated modified fused magnesia main aggregate includes: mixing silicon carbide powder with a median particle size of 1 μm and magnesium oxide powder with a median particle size of 5 μm at a mass ratio of 2:1; under conditions of 900℃ and 0.08MPa, introducing a nitrogen-silane mixed gas with a volume ratio of 95:5 at a gas flow rate of 20 L / h for 10 min, then stopping the gas flow and maintaining the temperature for 50 min; repeating the gas flow-temperature reaction cycle twice to form a silicon nitride layer; after stopping the gas flow, introducing argon gas at a flow rate of 8 L / h, and removing the material after it has naturally cooled to room temperature to obtain silicon carbide composite powder; and using fused magnesia (magnesia content ≥97.5 wt%): silicon carbide composite powder. Chromium trioxide powder (median particle size 1 μm): Phenolic resin powder (median particle size 3 μm) = 100:6:3:5 were mixed evenly and heated to 500℃ at 8℃ / min, and sintered for 2 hours. After cooling, the agglomerated powder was broken up, classified, and graded to obtain a coated modified fused magnesia main aggregate with a particle size distribution of 3mm < particle size ≤ 5mm accounting for 35wt%, 1mm < particle size ≤ 3mm accounting for 40wt%, 0.5mm < particle size ≤ 1mm accounting for 15wt%, and particle size ≤ 0.5mm accounting for 10wt%. (The silicon carbide composite powder and chromium trioxide powder were coated on the particle surface of the fused magnesia main aggregate using phenolic resin powder as a binder.)

[0064] The preparation of the surface-coated magnesium oxide fine powder includes: magnesium oxide fine powder with a particle size range of 0.1 mm to 0.5 mm, under the conditions of 150 °C and 0.12 MPa pressure, triethylaluminum vapor is introduced at a flow rate of 15 L / h for 30 min, and then the flow rate is switched to water vapor at 12 L / h for 25 min, so that an aluminum hydroxide layer is deposited on the surface of the magnesium oxide fine powder particles; then the temperature is increased to 800 °C at 6 °C / min and held for 2.5 h, so that the aluminum hydroxide layer is transformed into a dense alumina coating layer, and after cooling, the surface-coated magnesium oxide fine powder is obtained.

[0065] The preparation of the pre-reacted spinel precursor includes: weighing two raw materials at room temperature according to a mass ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate of 1.2:4, adding 2.2 times the total mass of deionized water, stirring at 250 r / min for 40 min to prepare a mixed salt solution, adjusting the pH to 9.5 with 4 wt% ammonia water under stirring at 30℃ and 400 r / min, stirring at 200 r / min for 40 min, aging at room temperature for 10 h, separating the precipitate and mother liquor by filtration, and using deionized water... The precipitate was repeatedly washed with deionized water (each time using twice the mass of the precipitate, for a total of 5 washes; the absence of white precipitate was confirmed by testing with silver nitrate solution). Finally, it was washed once with ethanol at 1.2 times the mass of the precipitate. The precipitate was filtered until it was loose and dried at 105℃ for 7 hours to obtain the primary precursor. The primary precursor was then subjected to heat treatment: the temperature was increased to 300℃ at 6℃ / min and held for 1.5 hours, then increased to 550℃ at 2℃ / min and held for 1.5 hours. After cooling to room temperature, the pre-reacted spinel precursor was obtained.

[0066] The ceramic sand aggregate has the following particle size distribution: 48 wt% for particles between 0.6 mm and 0.85 mm, 32 wt% for particles between 0.425 mm and 0.6 mm, and 20 wt% for particles between 0.25 mm and 0.425 mm. The median particle size of the γ-phase alumina powder is 5 μm. The effective content of the aluminum dihydrogen phosphate solution is 50%. The content of the alkaline silica sol is 50%. The median particle size of the zirconium boride powder is 1 μm.

[0067] The preparation method of the above-mentioned refractory ceramic matrix material for lining a smelting furnace includes the following steps:

[0068] According to the mass fractions, the coated modified fused magnesia main aggregate, ceramic sand main aggregate, surface-coated magnesia fine powder, γ-phase alumina micro powder, pre-reacted spinel precursor and zirconium boride micro powder are dry-mixed evenly to obtain a mixture; then aluminum dihydrogen phosphate solution, alkaline silica sol and water (the amount of water added is 7% of the mass of the mixture) are added in sequence and wet-mixed evenly to obtain a billet, that is, refractory ceramic matrix material;

[0069] The furnace lining is rammed in layers, with each layer not exceeding 100mm in thickness, and a construction bulk density of 2.8g / cm³. 3 ~3.0g / cm 3 The total thickness of the furnace lining is determined according to the actual furnace lining design. The furnace lining is then naturally dried (ambient temperature > 10℃) for 24 hours, heated at 10℃ / h to 200℃ and held for 10 hours, heated at 10℃ / h to 700℃ and held for 6 hours, heated at 15℃ / h to 1200℃ and held for 6 hours, and then naturally cooled to obtain the furnace lining of the refractory ceramic matrix material.

[0070] The raw materials used in the above embodiments are sourced as follows: phenolic resin from Wuhan Jiyesheng Chemical Co., Ltd.; ceramic sand from Dongguan Xinyuan Abrasives Co., Ltd., with a zirconium oxide content of 68%, silicon oxide of 31%, and the remainder being impurities; γ-phase alumina micro powder from Shanghai Jiaotong University Saiful (Baotou) New Materials Co., Ltd.; aluminum dihydrogen phosphate solution from Shandong Zhongli Petrochemical Technology Co., Ltd.; alkaline silica sol from Guangzhou Suize Environmental Protection Technology Co., Ltd., model SD10050; tetraethyl orthosilicate (TEOS) from Shandong Yukang Chemical Co., Ltd., with a purity of 99%; and zirconium boride from Ningbo Beigal New Materials Co., Ltd.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that no ceramic sand aggregate is added.

[0073] Comparative Example 2

[0074] The difference from Example 1 is that the surface-coated magnesium oxide fine powder is changed to 3.5 parts and the γ-phase alumina micro powder is changed to 10 parts.

[0075] Comparative Example 3

[0076] The difference from Example 1 is that no alkaline silica sol is added, and the aluminum dihydrogen phosphate solution is changed to 7 parts.

[0077] Comparative Example 4

[0078] The difference from Example 1 is that no pre-reacted spinel precursor is added.

[0079] Comparative Example 5

[0080] The difference from Example 1 is that the main aggregate of the coated modified fused magnesia is replaced by fused magnesia (the gradation of the fused magnesia is the same as that of the main aggregate of the coated modified fused magnesia).

[0081] Comparative Example 6

[0082] The difference from Example 1 is that in the preparation of the coated modified fused magnesia main aggregate, silicon carbide composite powder is not prepared, and silicon carbide composite powder is directly replaced by a mixture of silicon carbide powder and magnesium oxide powder in a certain mass ratio.

[0083] Comparative Example 7

[0084] The difference from Example 1 is that in the preparation of the coated modified fused magnesia main aggregate, the fused magnesia is not coated and modified. The coated modified fused magnesia main aggregate is directly replaced by a mixture of fused magnesia, silicon carbide composite powder and chromium trioxide powder in a certain mass ratio (the fused magnesia gradation is the same as that of the coated modified fused magnesia main aggregate).

[0085] Comparative Example 8

[0086] The difference from Example 1 is that no chromium trioxide powder is added in the preparation of the coated modified fused magnesia main aggregate.

[0087] Comparative Example 9

[0088] The difference from Example 1 is that the surface coating of magnesium oxide fine powder is replaced with magnesium oxide fine powder.

[0089] Comparative Example 10

[0090] The difference from Example 1 is that the particle size distribution of the main aggregate of ceramic sand is 0.6mm < particle size ≤ 0.85mm accounting for 100wt%.

[0091] Comparative Example 11

[0092] The difference from Example 1 is that the heating curve of the ramming material is modified from "heating to 220℃ at 9℃ / h and holding for 9h, heating to 650℃ at 12℃ / h and holding for 7h, heating to 1250℃ at 12℃ / h and holding for 5h" to "heating to 1250℃ at 12℃ / h and holding for 5h".

[0093] The above-mentioned refractory ceramic matrix materials were subjected to the following performance tests.

[0094] Test block preparation: Following the technical solutions of each embodiment and comparative example, dry powder raw materials were dry-mixed for 5 minutes until homogeneous, and liquid raw materials were added and wet-mixed for 15 minutes to form a uniform blank. The blank was then formed in a steel mold using a layered tamping method, with each layer not exceeding 100mm in thickness. Pressure was applied to control the construction bulk density to 2.9 ± 0.03 g / cm³. 3 The drying environment was set at 25°C and relative humidity <60% for 26 hours. The heating process was carried out according to the heating curves described in each embodiment, followed by natural cooling to room temperature. The sintered test blocks were cut and ground to the specified dimensions according to the standards for each testing item. All test blocks were dried in an oven at 110°C for 24 hours before testing, and then cooled to room temperature in a desiccator for testing.

[0095] I. Compressive strength:

[0096] Refer to GB / T 5072 "Test Method for Compressive Strength of Refractory Materials at Room Temperature" and GB / T 34218 "Test Method for Compressive Strength of Refractory Materials at High Temperature". Specimen size: 50mm × 50mm × 50mm cube. Loading rate: 1.0 MPa / s until failure. Determine the compressive strength at room temperature and at 1300℃ (heating to 1300℃ at 5℃ / min, holding for 30 minutes). Three parallel samples are required for each group.

[0097] II. Thermal shock stability:

[0098] Refer to GB / T 3001 "Test Method for Flexural Strength of Refractory Materials at Room Temperature" and GB / T 30873 "Test Method for Thermal Shock Resistance of Refractory Materials". Specimen size: 25mm × 25mm × 150mm strip specimen. Five parallel samples per group. First, determine the initial flexural strength of the specimen at room temperature and take the average value. Place the remaining part of the specimen in a high-temperature furnace preheated to 1300℃ and hold for 20 minutes. Quickly remove and immerse in a flowing water bath at 20℃ for 3 minutes, ensuring the water level is >20mm from the top surface of the specimen. Remove the specimen, wipe off surface moisture, and place it in air for 10 minutes. Repeat the above cycle 5 times. After the cycle, measure the flexural strength of the specimen after thermal shock at room temperature and take the average value. Flexural strength retention rate = (average flexural strength after thermal shock / initial average flexural strength) × 100%.

[0099] III. Resistance to molten slag erosion:

[0100] Refer to GB / T 8931 "Test Method for Slag Resistance of Refractory Materials" (Static Crucible Method). Specimen size: The billet was tamped and sintered according to parameters to prepare bottomed crucible specimens with an inner diameter of φ40mm and a depth of 40mm, with 3 parallel samples per group. 25.0g of synthetic metallurgical slag (chemical composition: 45wt% CaO, 35wt% SiO2, 10wt% Al2O3, 10wt% Fe2O3) was added to the crucible. The crucible was placed in a high-temperature furnace and heated to 1300℃ at a rate of 5℃ / min, holding for 3 hours. After cooling in the furnace, the crucible was longitudinally cut along its central axis. The maximum erosion depth and maximum penetration depth were measured.

[0101] IV. Erosion resistance:

[0102] Specimen dimensions: 100mm × 100mm × 30mm, with 3 parallel samples per group. The specimens were dried and weighed (m1). They were fixed on the abrasion testing machine, with the distance from the spray gun nozzle to the specimen surface 100mm and the spray angle 90°. Al2O3 abrasive (particle size 0.5mm-0.8mm) was used to scour the central area of ​​the specimen for 10 minutes at a rate of 50g / min under 0.4MPa air pressure. The specimens were removed, dust removed, and weighed (m2). The wear amount was calculated as: wear amount = m1 - m2.

[0103] V. Coefficient of thermal expansion:

[0104] Refer to GB / T 7320 "Test Method for Thermal Expansion of Refractory Materials". Specimen size: φ8mm×50mm cylinder, 3 parallel samples per group. Place the specimen in a thermal expansion apparatus and, in static air, heat from room temperature to 1300℃ at a rate of 5℃ / min. Test the average coefficient of thermal expansion from 20℃ to 1300℃.

[0105] VI. Changes in the permanent heating line:

[0106] Refer to GB / T 5988, "Test Method for Permanent Linear Change of Refractory Materials under Heating". Specimen size: 50mm × 50mm × 50mm cube, 3 parallel samples per group. Measure and record the initial length L0 on the edge of the specimen; place the specimen in a high-temperature furnace, heat to 1300℃ at a rate of 5℃ / min, and hold for 5 hours. After cooling in the furnace, measure the length L1 after heating at the original measurement position, and calculate the linear change rate: linear change rate = [(L1 - L0) / L0] × 100%.

[0107] Table 1 Performance test results (average)

[0108]

[0109] The superior performance of Examples 1 to 3 is attributed to the synergistic improvement in high-temperature resistance, erosion resistance, thermal shock stability, and mechanical strength achieved through optimized raw material formulation, modification of key components, and precise control of process parameters. A composite skeleton of coated modified fused magnesia and zirconia ceramic sand as main aggregates is employed. The modified fused magnesia is modified with silicon carbide composite powder and chromium trioxide, which not only enhances high-temperature resistance and erosion resistance but also strengthens the interfacial bonding with the matrix. The multi-gradation design of the zirconia ceramic sand fills the gaps between the main aggregates, reducing porosity, while the low expansion characteristics of zirconia alleviate thermal stress. These two factors synergistically improve the material's density and structural stability. An alumina coating layer with fine magnesium oxide powder improves the wettability of the particle interface and reduces high-temperature oxidation. Gamma-phase alumina micropowder forms a stable bonding network with aluminum dihydrogen phosphate solution and alkaline silica sol, preventing structural loosening at high temperatures. Pre-reacted spinel precursors generate a spinel phase in situ, forming a solid solution with the matrix, inhibiting slag diffusion and alleviating thermal stress. Zirconium boride micropowder further enhances erosion and corrosion resistance. Staged heating and curing prevents the formation of internal microcracks while promoting full reaction of all components, forming a uniform and stable microstructure, ultimately achieving a balanced and excellent performance across all indicators.

[0110] In Comparative Example 1, no ceramic sand aggregate was added: The multi-gradation design of the ceramic sand aggregate (zirconia material) achieved close packing with the coated modified fused magnesia aggregate, filling the gaps between the aggregates to reduce the porosity of the material. Without it, more interconnected pores are formed inside the material, making it easier for molten slag to penetrate along the pores at high temperatures. At the same time, abrasives are more likely to cut into the pores during the scouring process, causing particles to fall off. In addition, the lack of the low expansion characteristics of zirconia increases the overall coefficient of thermal expansion of the material, leading to thermal stress concentration during temperature fluctuations. This, in turn, results in a decrease in compressive strength and thermal shock stability, and an increase in erosion depth and wear.

[0111] In Comparative Example 2, the surface coating of fine magnesium oxide powder decreased while the γ-phase alumina powder increased: the alumina coating layer of fine magnesium oxide powder can construct a magnesium oxide-alumina transition interface, improving the wettability of particles and the matrix, while inhibiting the high-temperature oxidation of magnesium oxide. Reducing the fine magnesium oxide coating and adding excessive γ-phase alumina powder resulted in volume shrinkage during the high-temperature transformation of γ-phase alumina to the α-phase, easily leading to microcracks at the interface. Furthermore, the increased difference in thermal expansion coefficients between the excessive γ-phase alumina and the matrix accelerated crack propagation during thermal shock, resulting in a decrease in flexural strength retention. Simultaneously, the loose interfacial bonding reduced the material density, weakening its resistance to erosion and scour.

[0112] In Comparative Example 3, without the addition of alkaline silica sol, the addition of aluminum dihydrogen phosphate solution resulted in a composite cementing system formed by the alkaline silica sol and aluminum dihydrogen phosphate. The SiO2 in the silica sol reacted with the Al2O3 produced from the decomposition of aluminum dihydrogen phosphate to generate a low-temperature eutectic phase, improving high-temperature bonding strength and simultaneously inhibiting the structural loosening caused by the high-temperature decomposition of aluminum dihydrogen phosphate. Without silica sol, relying solely on aluminum dihydrogen phosphate for bonding, the phosphate easily decomposed into AlPO4 at high temperatures, accompanied by volume shrinkage, forming numerous micropores. The integrity of the material's internal structure was compromised, high-temperature strength decreased significantly, slag more easily eroded the cementing phase, and particles were prone to detachment due to insufficient adhesion during scouring, leading to a significant increase in the coefficient of thermal expansion and shrinkage rate.

[0113] In Comparative Example 4, no pre-reacted spinel precursor was added: During sintering, the pre-reacted spinel precursor generated an in-situ MgAl2O4 spinel phase. The spinel formed a solid solution with magnesium oxide and aluminum oxide in the matrix, reducing the difference in thermal expansion coefficients between the phases and alleviating thermal stress. At the same time, the chemical inertness of the spinel suppressed the Ca in the slag. 2+ Fe 3+ The diffusion of spinel phase is lost. Without spinel phase to regulate interface properties, the uneven thermal deformation of each phase during thermal shock leads to crack formation. The slag is prone to chemical reaction with the matrix and penetrates along the interface, resulting in decreased erosion resistance and thermal shock stability, and weakened mechanical properties.

[0114] In Comparative Example 5, the coated and modified fused magnesia aggregate was replaced with ordinary fused magnesia. The silicon carbide composite powder (surface silicon nitride layer) in the coated and modified fused magnesia aggregate improved its high-temperature resistance, while chromium trioxide and magnesium oxide formed a Cr2O3-MgO solid solution to strengthen the interfacial bonding. Ordinary fused magnesia lacked the above-mentioned modification layer and was prone to reacting with SiO2 in the slag at high temperatures to form a low-melting-point Mg2SiO4 phase, leading to aggregate softening. Furthermore, the interfacial bonding strength between ordinary fused magnesia and the matrix was low, making it prone to interfacial separation during thermal shock, which in turn significantly reduced mechanical strength, significantly deteriorated erosion and corrosion resistance, and increased the coefficient of thermal expansion.

[0115] In Comparative Example 6, the silicon carbide composite powder was replaced with a mixture of silicon carbide and magnesium oxide. The silicon nitride layer on the surface of the silicon carbide composite powder can isolate oxygen and inhibit the high-temperature oxidation of silicon carbide to form SiO2. Simultaneously, the interfacial compatibility between silicon nitride and magnesium oxide is superior to that of a direct mixture of silicon carbide and magnesium oxide, reducing interfacial defects. When the mixture is used directly, without the protection of the silicon nitride layer, silicon carbide is easily oxidized to form SiO2. SiO2 reacts with magnesium oxide to form low-melting-point Mg2SiO4, resulting in a porous interface. This leads to decreased internal structural stability, reduced strength and thermal shock resistance, and weakened resistance to erosion and scour.

[0116] In Comparative Example 7, the fused magnesia was not coated or modified: the coating treatment of modified fused magnesia (silicon carbide composite powder, chromium trioxide coating) improves the surface activity of the particles, enhances the chemical bonding with other components, and reduces the risk of particle detachment at high temperatures. Without coating, the fused magnesia has high surface inertness and is only simply mixed with the matrix. During thermal shock, the interface is prone to separation and cracking; at high temperatures, slag easily penetrates along the interface, and the particles are easily peeled off by the abrasive during scouring, resulting in a significant decrease in all performance indicators.

[0117] In Comparative Example 8, chromium trioxide powder was not added during the preparation of modified fused magnesia. Chromium trioxide forms Cr₂O₃-MgO and Cr₂O₃-SiC solid solutions with magnesium oxide and silicon carbide, reducing interfacial energy and promoting sintering densification. Simultaneously, the chemical stability of Cr₂O₃ enhances the material's resistance to slag erosion. Without chromium trioxide, the interfacial bonding strength is insufficient, preventing the formation of a continuous reinforcing phase during sintering, leading to increased material porosity. At high temperatures, the interface is prone to debonding, crack propagation accelerates during thermal shock, mechanical properties and erosion resistance decrease, and wear increases.

[0118] In Comparative Example 9, the surface-coated magnesium oxide fine powder was replaced with ordinary magnesium oxide fine powder. Ordinary magnesium oxide fine powder lacks an alumina coating layer, making it prone to reacting with moisture at high temperatures to form Mg(OH)₂. The decomposition of Mg(OH)₂ generates gas, leading to porosity within the material. Furthermore, ordinary magnesium oxide has low interfacial bonding strength with the matrix, making it susceptible to particle detachment during thermal shock. In contrast, the alumina layer of the coated powder blocks the contact between magnesium oxide and moisture, while also improving interfacial wettability. Its absence reduces material density, and weakens thermal shock stability, erosion resistance, and scour resistance to varying degrees.

[0119] In Comparative Example 10, the main aggregate of ceramic sand is a single particle size: the multi-gradation of ceramic sand (0.25-0.425mm, 0.425-0.6mm, 0.6-0.85mm) can achieve the densest packing, reducing porosity through the "coarse particle skeleton - fine particle filling" structure. A single particle size (0.6-0.85mm) cannot efficiently fill the gaps between coarse particles, resulting in poor dispersion and the formation of a large number of large-sized pores inside the material; at high temperatures, slag easily accumulates in the pores and erodes the matrix, and during scouring, the abrasive is prone to stress concentration at the pores, leading to particle peeling, which in turn reduces the resistance to erosion and scouring, and slightly weakens the mechanical properties.

[0120] The simplified heating curve in Comparative Example 11: The original heating curve (staged heating and holding) allows for slow evaporation of moisture and gradual decomposition of organic matter, avoiding stress concentration caused by rapid heating. After simplification to direct heating, moisture and organic matter evaporate rapidly at low temperatures, forming numerous residual pores; the large temperature gradient at high temperatures during sintering leads to uneven shrinkage within the material, resulting in microcracks; ultimately, the material's density decreases, and its mechanical properties, thermal shock stability, erosion resistance, and scour resistance significantly decline, with more pronounced heating shrinkage.

Claims

1. A refractory ceramic-based material for lining a smelting furnace, characterized in that, The materials include the following raw materials in parts by weight: 75-80 parts of coated modified fused magnesia main aggregate, 10-15 parts of ceramic sand main aggregate, 8-12 parts of surface-coated magnesia fine powder, 2-5 parts of γ-phase alumina micro powder, 3-5 parts of aluminum dihydrogen phosphate solution, 2-4 parts of alkaline silica sol, 3-5 parts of pre-reacted spinel precursor, and 0.5-1 part of zirconium boride micro powder; The coated modified fused magnesia main aggregate is prepared by mixing fused magnesia, silicon carbide composite powder, chromium trioxide powder and phenolic resin powder in a mass ratio of 100:(6-8):(2-3):(5-7) and sintering; the silicon carbide composite powder is prepared by mixing silicon carbide powder and magnesium oxide powder in a mass ratio of (2-3):1 and depositing a silicon nitride layer on the particle surface. The surface-coated magnesium oxide fine powder is magnesium oxide fine powder particles coated with aluminum oxide; The pre-reacted spinel precursor is prepared by mixing magnesium nitrate hexahydrate and aluminum nitrate nonahydrate with deionized water to form a mixed salt solution, reacting at pH 9.0-9.5, aging, and heat treatment. The main aggregate of the ceramic sand is made of zirconium oxide; The heating and curing parameters of the material after tamping are as follows: heat up to 200℃~250℃ at 8℃ / h~10℃ / h and hold for 8h~10h, heat up to 600℃~700℃ at 10℃ / h~15℃ / h and hold for 6h~8h, heat up to 1200℃~1300℃ at 10℃ / h~15℃ / h and hold for 4h~6h, then cool naturally.

2. The refractory ceramic matrix material for lining a smelting furnace according to claim 1, characterized in that, The preparation of the coated modified fused magnesia main aggregate includes: mixing silicon carbide powder and magnesium oxide powder at a mass ratio of (2-3):1, reacting them at 800℃-900℃ and 0.08MPa-0.1MPa with a nitrogen-silane mixed gas to form a silicon nitride layer, and obtaining silicon carbide composite powder; mixing the fused magnesia: silicon carbide composite powder: chromium trioxide powder: phenolic resin powder in a mass ratio of 100:(6-8):(2-3):(5-7), sintering, cooling, dispersing and classifying, and grading to obtain the coated modified fused magnesia main aggregate.

3. The refractory ceramic matrix material for lining a smelting furnace according to claim 2, characterized in that, The median particle size of both the silicon carbide powder and the magnesium oxide powder is 1 μm to 5 μm; the volume ratio of nitrogen to silane in the nitrogen-silane mixed gas is (92-95):(5-8); the magnesium oxide content of the fused magnesia is ≥95 wt%; the median particle size of the chromium trioxide powder is 1 μm to 5 μm; the median particle size of the phenolic resin powder is 1 μm to 3 μm; the sintering is carried out at 500℃ to 600℃ for 1 to 2 hours; the particle size distribution of the coated modified fused magnesia main aggregate is as follows: 3 mm < particle size ≤ 5 mm accounts for 20 wt% to 25 wt%, 1 mm < particle size ≤ 3 mm accounts for 25 wt% to 30 wt%, 0.5 mm < particle size ≤ 1 mm accounts for 15 wt% to 20 wt%, and particle size ≤ 0.5 mm accounts for 10 wt% to 15 wt%.

4. The refractory ceramic matrix material for lining a smelting furnace according to claim 1, characterized in that, The preparation of the surface-coated magnesium oxide fine powder includes: continuously introducing triethylaluminum vapor into the magnesium oxide fine powder at 130℃~150℃ and 0.12MPa~0.15MPa, and then switching to water vapor to deposit an aluminum hydroxide layer on the surface of the magnesium oxide fine powder particles; holding the temperature at 800℃~850℃ for 1.5h~2.5h to convert the aluminum hydroxide layer into an aluminum oxide coating layer; and obtaining the surface-coated magnesium oxide fine powder after cooling.

5. The refractory ceramic matrix material for lining a smelting furnace according to claim 4, characterized in that, The particle size range of the magnesium oxide fine powder is 0.1 mm to 0.5 mm; the introduction time of the triethylaluminum vapor is 30 min to 40 min; and the introduction time of the water vapor is 25 min to 35 min.

6. The refractory ceramic matrix material for lining a smelting furnace according to claim 1, characterized in that, The preparation of the pre-reacted spinel precursor includes: weighing two raw materials at a mass ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate (1.2-1.3):4, preparing a mixed salt solution with 1.8-2.2 times the total mass of the raw materials in deionized water, adjusting the pH to 9.0-9.5 with ammonia, stirring, aging, filtering to separate the precipitate from the mother liquor, washing the precipitate with deionized water and ethanol, drying to obtain the primary precursor; and subjecting the primary precursor to heat treatment to obtain the pre-reacted spinel precursor.

7. A refractory ceramic matrix material for lining a smelting furnace according to claim 6, characterized in that, The parameters for the heat treatment are as follows: heating at 4℃ / min to 6℃ / min to 300℃ to 350℃, holding at that temperature for 1h to 1.5h, heating at 2℃ / min to 3℃ / min to 400℃ to 550℃, holding at that temperature for 1.5h to 2h, and then cooling to room temperature.

8. The refractory ceramic matrix material for lining a smelting furnace according to claim 1, characterized in that, The particle size distribution of the main aggregate of the ceramic sand is as follows: 0.6 mm < particle size ≤ 0.85 mm accounts for 45 wt% to 50 wt%, 0.425 mm < particle size ≤ 0.6 mm accounts for 30 wt% to 35 wt%, and 0.25 mm < particle size ≤ 0.425 mm accounts for 15 wt% to 25 wt%; the median particle size of the γ-phase alumina micro powder is 1 μm to 5 μm; and the median particle size of the zirconium boride micro powder is 1 μm to 3 μm.

9. The method for preparing a refractory ceramic matrix material for smelting furnace lining as described in claim 1, characterized in that, Includes the following steps: S1: According to the mass fractions, the coated modified fused magnesia main aggregate, ceramic sand main aggregate, surface-coated magnesia fine powder, γ-phase alumina micro powder, pre-reacted spinel precursor and zirconium boride micro powder are dry-mixed evenly to obtain a mixture; then aluminum dihydrogen phosphate solution, alkaline silica sol and water are added and wet-mixed evenly to obtain refractory ceramic matrix material. S2: The furnace lining is rammed in layers, dried naturally, and then heated to cure, resulting in a furnace lining of refractory ceramic matrix material.

10. The method for preparing a refractory ceramic matrix material for smelting furnace lining according to claim 9, characterized in that, In S1, the amount of water added is 5% to 7% of the mass of the mixture; in S2, the natural drying time is 24h to 30h; the parameters for the heating and curing are: heating at 8℃ / h to 10℃ / h to 200℃ to 250℃ and holding for 8h to 10h, heating at 10℃ / h to 15℃ / h to 600℃ to 700℃ and holding for 6h to 8h, heating at 10℃ / h to 15℃ / h to 1200℃ to 1300℃ and holding for 4h to 6h, followed by natural cooling.

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