Aluminum-chromium residue-based high-strength ceramicized refractory material and preparation method thereof

Abstract

This invention belongs to the field of new materials technology, specifically relating to a high-strength ceramicized refractory material based on aluminum-chromium slag, its preparation method, and its application. The high-strength ceramicized refractory material based on aluminum-chromium slag is prepared from the following raw materials in parts by weight: 92-97 parts of aluminum-chromium slag matrix, 3-8 parts of binder, and an aluminum-silicon composite additive. The amount of the aluminum-silicon composite additive is 2%-10% of the total mass of the aluminum-chromium slag matrix and binder; wherein the binder is lignosulfonate; and the aluminum-silicon composite additive is a mixture of metallic aluminum powder and silicon powder. The high-strength ceramicized refractory material based on aluminum-chromium slag prepared by this invention exhibits excellent compressive strength, density, and resistance to molten slag erosion, and also has good environmental safety.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically the field of refractory material design, and provides an aluminum-chromium slag-based high-strength ceramicized refractory material and its preparation method. Background Technology

[0002] Aluminum-chromium slag is an industrial solid waste generated during the aluminothermic smelting of metallic chromium. Its main mineral phases are corundum (α-Al₂O₃) and aluminum-chromium solid solution ((Al, Cr)₂O₃). Both phases possess high refractoriness, high hardness, and excellent chemical stability, making them theoretically a highly promising source of high-performance refractory materials. However, due to its content of leached chromium (especially hexavalent chromium), it is classified as hazardous waste (HW₂I), which imposes severe environmental safety constraints on its large-scale, high-value-added resource utilization and has led to its enormous resource value being overlooked for a long time.

[0003] Currently, conventional methods of disposing of and utilizing aluminum-chromium slag have significant shortcomings in terms of value: First, its use as inexpensive aggregate or admixture in low-end building materials (such as roadbed filling) results in extremely low added value, completely failing to match its performance potential as a high-quality refractory matrix; second, the recovery of valuable metals through complex wet processes is a lengthy, energy-intensive process that is prone to secondary pollution (such as high-salinity wastewater). Therefore, developing a "high-value" technology route that can directly convert aluminum-chromium slag into high-performance refractory products is crucial to realizing its resource potential. However, this approach must simultaneously address two core issues: first, ensuring the long-term environmental safety of chromium in the final product; and second, overcoming the problems of low strength and poor performance in existing utilization methods, truly achieving a qualitative transformation from "waste" to "high-performance material."

[0004] To achieve high erosion resistance, the development of traditional high-performance refractory binders faces two bottlenecks: (1) Resin bonding and its environmental and cost bottlenecks: Phenolic resin is commonly used as a binder for high-performance refractory materials due to its fast curing at room temperature and high bonding strength. However, there are environmental concerns during its production and use, and the raw material cost is relatively high. More importantly, it undergoes violent pyrolysis in the medium temperature range of 400℃ to 800℃, resulting in a "strength trough" in the material, which seriously restricts its safe application under medium temperature baking conditions. (2) Performance bottlenecks of green binders: Biomass-based binders, represented by lignin sulfonate and dextrin, are derived from industrial by-products such as papermaking and have significant advantages such as low cost, wide availability, and environmental friendliness. However, these binders generally have problems such as low residual carbon rate, slow pyrolysis process, and severe attenuation of bonding force, resulting in materials with extremely low medium temperature strength and difficulty in meeting high performance requirements after burning. How to improve the room temperature and medium temperature strength of these green binder systems is a key bottleneck to achieving comprehensive greening of refractory materials.

[0005] In summary, existing technologies have the following interconnected systemic gaps and disconnects in terms of resource utilization of aluminum-chromium slag and meeting the performance requirements of high-end refractory materials: (1) Disconnect between high-value utilization and greening: Existing technologies have failed to coordinate the high-value utilization of aluminum chromium slag with the comprehensive greening of the refractory material production process (including the application of green binders).

[0006] (2) Green binders are out of sync with high performance requirements: When green binders such as lignin sulfonate are used directly, the inherent fatal defects of the system, such as mid-temperature strength collapse and insufficient final strength, are completely inherited, which cannot meet the requirements of high performance.

[0007] (3) Existing modification paths are incompatible with green systems: Traditional performance enhancement paths (such as adding graphite or metal) may lead to oxidation sensitivity issues or rely on harsh reduction conditions, which are inherently incompatible with or even contradictory to green binder systems and mild oxidation atmosphere processes.

[0008] Therefore, existing technologies lack an integrated solution that can break down all the above-mentioned disconnects: a technical solution that can eliminate graphite and highly reactive metals, and simultaneously achieve high-value utilization of aluminum-chromium slag, greening of binders, and high-performance materials through innovative component design in a mild atmosphere. Summary of the Invention

[0009] In view of the problems and shortcomings of the existing technology, the purpose of this invention is to provide an aluminum-chromium slag-based high-strength ceramicized refractory material and its preparation method.

[0010] To achieve the objectives of this invention, the technical solution adopted is as follows: The first aspect of this invention provides a high-strength ceramicized refractory material based on aluminum-chromium slag, which is prepared from the following raw materials in parts by weight: 92-97 parts of aluminum-chromium slag matrix, 3-8 parts of binder, and aluminum-silicon composite additive, wherein the amount of aluminum-silicon composite additive is 2%-10% of the total mass of aluminum-chromium slag matrix and binder; wherein the binder is lignosulfonate; and the aluminum-silicon composite additive is a mixture of metallic aluminum powder and silicon powder.

[0011] According to the above-mentioned high-strength ceramicized refractory material based on aluminum-chromium slag, preferably, the mass ratio of metallic aluminum powder to silicon powder in the aluminum-silicon composite additive is 1:(0.2~1). More preferably, the mass ratio of metallic aluminum powder to silicon powder in the aluminum-silicon composite additive is 1:0.5.

[0012] According to the above-mentioned aluminum-chromium slag-based high-strength ceramicized refractory material, preferably, the particle size of the aluminum powder is ≤45μm and the particle size of the silicon powder is ≤45μm.

[0013] According to the above-mentioned high-strength ceramicized refractory material based on aluminum-chromium slag, preferably, the aluminum-chromium slag matrix is ​​composed of the following particle size distribution by mass percentage: 25%–30% aluminum-chromium slag particles with a particle size of 5–3 mm, 20%–26% aluminum-chromium slag particles with a particle size of 3–1 mm, 10%–15% aluminum-chromium slag particles with a particle size of 1–0 mm, and 30%–35% aluminum-chromium slag fine powder with a particle size ≤0.088 mm.

[0014] According to the above-mentioned high-strength ceramicized refractory material based on aluminum-chromium slag, preferably, the lignosulfonate is at least one of calcium lignosulfonate, sodium lignosulfonate, and magnesium lignosulfonate.

[0015] According to the above-mentioned high-strength ceramicized refractory material based on aluminum-chromium slag, preferably, the chemical composition of the aluminum-chromium slag is: Al2O3 75-90wt%, Cr2O3 8-12wt%, SiO2 < 3wt%, Fe2O3 < 1wt%.

[0016] According to the above-mentioned high-strength ceramicized refractory material based on aluminum-chromium slag, preferably, the aluminum-chromium slag is a solid solution particle obtained by water quenching and rapid cooling after the aluminothermic smelting of metallic chromium.

[0017] The second aspect of this invention provides a method for preparing the aluminum-chromium slag-based high-strength ceramicized refractory material described in the first aspect, comprising the following steps: S1: Add the binder to water, mix well, and obtain a binder solution; S2: Mix the aluminum-chromium slag matrix with the aluminum-silicon composite additive to obtain a dry mixture; add the binder solution to the dry mixture and mix well to obtain a wet mixture; S3: Press the wet mixture into a blank, and bake the blank at 150-250°C to obtain a cured blank; S4: The solidified preform is calcined at 800-1200℃ for 4-8 hours to obtain alumina-chromium slag-based high-strength ceramicized refractory material.

[0018] According to the above preparation method, preferably, in step S4, the calcination treatment is carried out under an air or nitrogen atmosphere.

[0019] According to the above preparation method, preferably, in step S1, the mass ratio of the binder to water is 1:(0.5 to 1:2).

[0020] According to the above preparation method, preferably, in step S3, the pressure of the pressing process is 100-200 MPa.

[0021] According to the above preparation method, preferably, in step S3, the baking time is 6 to 24 hours.

[0022] The third aspect of this invention provides the application of the aluminum-chromium slag-based high-strength ceramicized refractory material described in the first aspect above in the kiln lining.

[0023] Compared with the prior art, the positive and beneficial effects achieved by the present invention are as follows: (1) This invention uses aluminum-chromium slag as the matrix, lignosulfonate as the binder, and aluminum-silicon composite additive as the reinforcing phase to prepare refractory materials. The aluminum-silicon composite additive exhibits a stepped reinforcing effect in the lignosulfonate-bonded aluminum-chromium slag system through three characteristic temperature nodes (200℃, 600℃, and 1000℃). Among them, in the 200℃ curing and reinforcing stage, the aluminum-silicon composite additive acts as an active filler, significantly improving the initial density and curing strength of the green body, providing a more uniform and denser matrix for subsequent heat treatment. In the 600℃ medium-temperature support stage, at the temperature point where the lignosulfonate pyrolysis is most intense and the bonding strength declines most severely, the aluminum component in the aluminum-silicon composite additive... The reaction occurs preferentially, and corundum phase is generated in situ. These early-formed ceramic phases act as a micro-skeleton when the organic binder network fails, providing key mechanical support for the matrix and significantly inhibiting pore coarsening and structural loosening. Therefore, the aluminum-silicon composite additive can effectively overcome the inherent "mid-temperature strength trough" of lignin sulfonate binders, which is the core breakthrough of this invention. In the 1000℃ high-temperature ceramicization stage: as the heat treatment temperature rises to 1000℃, the silicon component is oxidized to generate active SiO2, which reacts in situ with the corundum phase generated by the inherent Al2O3 and aluminum component in the aluminum-chromium slag to generate mullite (3Al2O3·2SiO2) high-temperature reinforcing phase. The mullite phase exhibits good interfacial compatibility with the aluminum-chromium slag matrix. Its acicular crystal structure can pin grain boundaries and deflect cracks, while the accompanying volume effect further fills the residual pores, achieving a secondary leap in strength and density. Moreover, experimental verification by this invention shows that the sample with added aluminum-silicon composite additives achieves a room temperature compressive strength of 104.43 MPa after heat treatment at 1000℃, and the apparent porosity is reduced to 12.6%. Compared with the control sample without additives (52.34 MPa, 15.01%), it achieves a synergistic enhancement effect of increasing strength by 99.5% and reducing porosity by 16.1%.

[0024] (2) In the existing field of harmless utilization of chromium-containing solid waste, aluminum powder is usually used as a reducing agent for hexavalent chromium, and it must rely on a strong reducing atmosphere and a high temperature above 1500℃ to achieve its function. In this invention, aluminum powder and silicon powder are used in combination under a non-strong reducing atmosphere (such as air), giving aluminum powder a brand-new technical function: in the medium temperature range (600℃), it acts as a structural support agent for aluminum powder, and provides immediate reinforcement in the critical temperature range of lignin sulfonate binder pyrolysis failure, effectively suppressing the "strength trough"; in synergy with silicon components, it participates in the in-situ generation of mullite (3Al2O3·2SiO2) reinforcing phase in the high temperature range (1000℃), realizing a second leap in strength. Moreover, the aluminum-silicon composite additive used in this invention is not a simple mixture of metallic aluminum powder and silicon powder, but produces a significant synergistic enhancement effect—aluminum powder preferentially oxidizes to form a corundum skeleton, and the active SiO2 generated by the oxidation of silicon powder reacts in situ with Al2O3 in aluminum-chromium slag and the corundum phase generated by aluminum powder to form a mullite reinforcing phase. Both are indispensable and together construct a dense ceramic bonding network. This application has experimentally demonstrated that the room temperature compressive strength of the ceramicized refractory material prepared with the aluminum-silicon composite additive is significantly higher than that of the refractory material prepared with aluminum powder or silicon powder. Furthermore, the resistance to coal gangue slag penetration depth and apparent porosity of the ceramicized refractory material prepared with the aluminum-silicon composite additive are significantly lower than those of the refractory material prepared with aluminum powder or silicon powder.

[0025] (3) In this invention, the mass ratio of metallic aluminum powder to silicon powder in the aluminum-silicon composite additive is controlled to be 1: (0.2~1). This is because the research process found that when the silicon powder content is too low, the silicon powder cannot form an effective mullite reinforcing phase with the aluminum powder. Instead, it has a negative effect due to the "dilution" of the skeleton effect of the aluminum powder, resulting in a decrease in the strength of the refractory material. Only when the silicon powder content reaches a certain threshold (aluminum-silicon ratio ≥ 1: 0.2) can the aluminum powder and silicon powder trigger a synergistic reaction to generate a continuous mullite reinforcing phase and achieve a significant improvement in performance. When the aluminum-silicon ratio is too high (e.g., 1: 1.2), the silicon content is too high, and the excess unreacted SiO2 may form a glass phase, which will damage the strength of the refractory material and lead to an increase in porosity.

[0026] (4) In preparing ceramicized refractory materials, the present invention first dry-mixes the aluminum-chromium slag matrix with the aluminum-silicon composite additive to ensure uniform dispersion of the aluminum-silicon composite additive in the aggregate; subsequently, when the binder solution is added to the dry mix, since the aluminum powder has been diluted and dispersed by the aggregate, and the wet mixing time is short (≤40 minutes), the significant reaction between the aluminum powder and water can be effectively suppressed, ensuring the quality of the green body forming and improving the initial strength of the green body.

[0027] (5) The high-strength ceramic refractory material preparation process of the present invention does not rely on a strong reducing atmosphere, the heat treatment temperature is significantly lower than that of existing similar technologies, the process window is wider, the production cost is lower, and the resource utilization of aluminum chromium slag has been transformed from "harmless" to "high-performance".

[0028] (6) This invention uses aluminum-chromium slag as the matrix, lignin sulfonate as the binder, and aluminum-silicon composite additive as the reinforcing phase. Under conditions completely free of graphite and without the need for a strong reducing atmosphere, the post-firing strength of the green refractory material at 1000℃ is increased from 52.34 MPa (without additives) to 104.43 MPa, and the apparent porosity is reduced from 15.01% to 12.6%. This performance level indicates that this invention, through the introduction of aluminum-silicon composite additive, successfully solves the long-standing technical problem of "intermediate-temperature strength collapse and insufficient final strength" in green binder systems such as lignin sulfonate, providing a practical and feasible green technology path for the high-value-added resource utilization of aluminum-chromium slag. Attached Figure Description

[0029] Figure 1 The results show the macroscopic cross-section comparison of the ceramicized refractory material, the additive-free refractory material, and the commercially available high-alumina brick after being eroded by strongly alkaline dolomite slag (1400℃, 5h); where a is the commercially available high-alumina brick, b is the additive-free refractory material, and c is the ceramicized refractory material prepared in Example 1 of this invention. Figure 2 The results show the effect of aluminum-silicon composite additives on the compressive strength of refractory materials under different heat treatment temperatures; where 0% composite additives represent a blank without additives, and 4% composite additives represent a blank obtained after pressing and molding in step S3 of Example 1 of this invention. Figure 3 The results show the effects of aluminum-silicon composite additives on refractory materials under different heat treatment temperatures; where 0% composite additives represent a blank without additives, and 4% composite additives represent a blank obtained after pressing and molding in step S3 of Example 1 of this invention. Figure 4 The statistical results show the effect of different heat treatment temperatures on the leaching behavior of chromium in refractory materials; where 0% composite additive represents a blank without additives, and 4% composite additive represents a blank obtained after pressing and molding in step S3 of Example 1 of this invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0031] The following embodiments are only for further elaboration of the present invention. It should be noted that all techniques and scientific terms used in this invention, unless otherwise stated, have the same meaning as those in the technical field to which this invention pertains. Experimental methods in the following embodiments that do not specify specific conditions all employ conventional techniques in this technical field or follow the conditions recommended by the manufacturer; reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0032] (I) Discussion on the types of additives In order to study the effects of different types of additives on the properties of the prepared refractory materials, the present invention conducted Example 1, Comparative Example 1, and Comparative Example 2.

[0033] Example 1: A high-strength ceramicized refractory material based on aluminum-chromium slag is prepared from the following raw materials in parts by weight: 96 parts aluminum-chromium slag matrix, 4 parts binder, and additives. The additives are aluminum-silicon composite additives, and the amount of the aluminum-silicon composite additives is 4% of the total mass of the aluminum-chromium slag matrix and binder. The binder is calcium lignosulfonate. The aluminum-silicon composite additive is composed of aluminum powder and silicon powder mixed at a mass ratio of 1:0.5, wherein the particle size of the aluminum powder is ≤45μm, and the particle size of the silicon powder is ≤45μm. The aluminum-chromium slag matrix is ​​composed of the following particle size distribution in weight percentages: 29.2% aluminum-chromium slag particles with a particle size of 5–3mm, 25% aluminum-chromium slag particles with a particle size of 3–1mm, 12.5% ​​aluminum-chromium slag particles with a particle size of 1–0mm, and 33.3% fine aluminum-chromium slag powder with a particle size ≤0.088mm. The aluminum-chromium slag is a solid solution particle obtained by water quenching and rapid cooling after smelting metallic chromium by the aluminothermic process. The chemical composition of the aluminum-chromium slag is: Al2O3 75-90wt%, Cr2O3 8-12wt%, SiO2 <3wt%, Fe2O3 <1wt%.

[0034] The specific steps for preparing the above-mentioned high-strength ceramicized refractory material based on aluminum-chromium slag are as follows: S1: Add the binder to water and mix well to obtain a binder solution; wherein the mass ratio of binder to water is 1:1; S2: Add the aluminum-chromium slag matrix and aluminum-silicon composite additive to a mixer and dry mix for 30 minutes to obtain a dry mixture; add the binder solution prepared in step S1 to the dry mixture and mix well to obtain a wet mixture; S3: Place the wet mixture in a mold and press it under 150 MPa pressure to obtain a green body. Place the green body in a drying oven and bake it at 180°C for 12 hours to fully cure the binder and obtain a cured green body. S4: Place the solidified preform obtained in step S3 into a muffle furnace, heat it to 1000℃ at 5℃ / min in an air atmosphere, hold it at that temperature for 6 hours, and then cool it with the furnace to obtain the aluminum chromium slag-based high-strength ceramicized refractory material.

[0035] Comparative Example 1: The content of Comparative Example 1 is basically the same as that of Example 1, except that the additive is aluminum powder and the amount of aluminum powder is 4% of the total mass of aluminum chromium slag matrix and binder.

[0036] Comparative Example 2: The content of Comparative Example 2 is basically the same as that of Example 1, except that the additive is silicon powder, and the amount of silicon powder is 4% of the total mass of aluminum chromium slag matrix and binder.

[0037] The properties of the refractory materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 were tested, and the test results are shown in Table 1. The test standard for room temperature compressive strength was GB / T 5072, the test standard for apparent porosity was GB / T 2997, and the resistance to dolomite slag erosion (1400℃, 5h) and resistance to coal gangue slag erosion (1400℃, 5h) were both tested using the static crucible method.

[0038] As shown in Table 1, the compressive strength (104.43 MPa) of the refractory material prepared in Example 1 was increased by 18.5% and 36.8% compared with that prepared with only aluminum powder (88.16 MPa) and that prepared with only silicon powder (76.34 MPa), respectively. The apparent porosity was also correspondingly reduced. Furthermore, the refractory material prepared in Example 1 exhibited better resistance to coal gangue slag erosion than that in Comparative Examples 1 and 2. This indicates that the effect of the aluminum-silicon composite additive is significantly better than that of using aluminum powder or silicon powder alone. It also demonstrates that the aluminum-silicon composite additive is not simply a mixture of aluminum and silicon powder, but rather produces a significant synergistic reinforcing effect.

[0039] (II) Discussion on the mass ratio of aluminum powder to silicon powder in aluminum-silicon composite additives: In order to study the effects of different types of additives on the properties of the prepared refractory materials, Examples 2 to 6, Comparative Example 3 and Comparative Example 4 were conducted in this invention.

[0040] Example 2: The content of Example 2 is basically the same as that of Example 1, except that the aluminum-silicon composite additive is made by mixing aluminum powder and silicon powder in a mass ratio of 1:0.2.

[0041] Example 3: The content of Example 3 is basically the same as that of Example 1, except that the additive is an aluminum-silicon composite additive, which is made by mixing aluminum powder and silicon powder in a mass ratio of 1:0.4.

[0042] Example 4: The content of Example 4 is basically the same as that of Example 1, except that the additive is an aluminum-silicon composite additive, which is made by mixing aluminum powder and silicon powder in a mass ratio of 1:0.6.

[0043] Example 5: The content of Example 5 is basically the same as that of Example 1, except that the additive is an aluminum-silicon composite additive, which is made by mixing aluminum powder and silicon powder in a mass ratio of 1:0.8.

[0044] Example 6: The content of Example 6 is basically the same as that of Example 1, except that the additive is an aluminum-silicon composite additive, which is made by mixing aluminum powder and silicon powder in a mass ratio of 1:1.0.

[0045] Comparative Example 3: The content of Comparative Example 3 is basically the same as that of Example 1, except that the additive is an aluminum-silicon composite additive, which is made by mixing aluminum powder and silicon powder in a mass ratio of 1:0.1.

[0046] Comparative Example 4: The content of Comparative Example 4 is basically the same as that of Example 1, except that the additive is an aluminum-silicon composite additive, which is made by mixing aluminum powder and silicon powder in a mass ratio of 1:1.2.

[0047] The properties of the refractory materials prepared in Examples 2 to 6, Comparative Examples 3 and 4 were tested, and the test results are shown in Table 2. The test standard for room temperature compressive strength was GB / T 5072, and the test standard for apparent porosity was GB / T 2997.

[0048] As shown in Table 2, when the aluminum-silicon mass ratio is within the range of 1:(0.2-1), the room temperature compressive strength of the material remains above 72 MPa, and the apparent porosity is below 14.2%, exhibiting excellent comprehensive performance. Specifically, when the aluminum-silicon ratio is 1:0.5, the refractory material reaches its peak performance (compressive strength 104.43 MPa, porosity 12.6%). When the aluminum-silicon ratio is below 1:0.2 (e.g., 1:0.1), the silicon content is too low, failing to fully generate the mullite reinforcing phase, resulting in a decrease in strength to 74.92 MPa. When the aluminum-silicon ratio is above 1:1 (e.g., 1:1.2), the silicon content is too high, and excess unreacted SiO2 may form a glassy phase, which conversely damages the material's strength (reducing it to 56.33 MPa) and increases porosity. Therefore, the preferred aluminum-silicon mass ratio of this invention is 1:(0.2-1), within which the optimal synergistic effect of aluminum powder and silicon powder can be achieved.

[0049] (III) Comparison of the performance of the ceramicized refractory material of this invention with additive-free refractory materials and commercially available high-alumina bricks: To further verify the performance of the ceramicized refractory material of the present invention, the performance of the ceramicized refractory material prepared in Example 1 of the present invention was compared with that of commercially available high-alumina bricks and refractory materials without additives. The results are as follows: Figure 1 As shown in Table 3. The commercially available high-alumina bricks used were Grade 1 high-alumina bricks (brand LZ-75) conforming to the national standard GB / T 2988-2012 "High-Alumina Bricks". Their typical properties were: room temperature compressive strength ≥60MPa, apparent porosity ≤23%. The preparation method of the additive-free refractory material was basically the same as in Example 1, except that no aluminum-silicon additives were added to the formula, i.e., the amount of aluminum-silicon additives was 0%; the remaining raw material ratios, particle size distribution of the aluminum-chromium slag matrix, and the refractory material preparation method were all the same as in Example 1.

[0050] Depend on Figure 1 It can be seen that traditional high-alumina bricks (LZ-75) show severe erosion (erosion depth 12.1 mm); refractory materials without additives do not show obvious erosion, but the structure is relatively loose; the ceramicized refractory material prepared in Example 1 of this invention does not show obvious erosion, the crucible cross section is flat and the structure is dense, which directly reflects the contribution of ceramicization and densification to improving the structural integrity of the material.

[0051] As shown in Table 3, compared with the additive-free refractory material, the ceramicized refractory material prepared in Example 1 achieved a room temperature compressive strength of 104.43 MPa after heat treatment at 1000℃, representing a 99.5% increase in compressive strength compared to the additive-free refractory material; the apparent porosity decreased from 15.01% to 12.6%, a reduction of 16.1%. This data demonstrates that the alumina-silicon composite additive significantly improves the mechanical properties and density of the material through the synergistic effect of medium-temperature support and high-temperature ceramicization. In the strongly alkaline dolomite slag erosion test, the erosion depth of commercially available high-alumina bricks reached 12.1 mm, while the erosion depth of Example 1 of this invention and the additive-free refractory material was less than 1 mm, with no significant erosion observed. In the acidic coal gangue slag penetration test, the penetration depth of Example 1 (1.6 mm) was significantly lower than that of the additive-free refractory material (2.9 mm) and the commercially available high-alumina brick (5.1 mm), indicating that the material of this invention possesses excellent resistance to both alkaline erosion and acidic penetration. Furthermore, the chromium ion leaching concentration of the ceramicized refractory material prepared in Example 1 was 10.88 mg / L, which is lower than the limit for total chromium (15 mg / L) in the "Hazardous Waste Identification Standard". Compared with the refractory material without additives (16.88 mg / L), the chromium ion leaching concentration was reduced by approximately 35.6%, indicating that the technical solution of the present invention not only achieves high-performance materials but also significantly reduces the environmental risk of aluminum-chromium slag. The ceramicized refractory material prepared by the present invention has good environmental safety. In summary, the compressive strength, density, slag erosion resistance, and acid penetration resistance of the ceramicized refractory material prepared by the present invention are significantly higher than those of the refractory material without additives and commercially available high-alumina bricks. Moreover, the chromium ion leaching concentration of the ceramicized refractory material of the present invention is significantly lower than that of the refractory material without additives.

[0052] (iv) Effects of aluminum-silicon composite additives on compressive strength, apparent porosity and chromium leaching of ceramicized refractories at different heat treatment temperatures To further verify the performance of the ceramicized refractory material of the present invention, the green body obtained by pressing in step S3 of Example 1 was heat-treated at 200℃, 600℃, and 1000℃, respectively, with a holding time of 6 hours (consistent with the holding time in step S4 of Example 1). The changes in compressive strength and apparent porosity of the refractory material under different heat treatment temperatures were studied, with a green body without additives used as a comparison. The formulation of the green body without additives was basically the same as that of Example 1, except that: no aluminum-silicon additives were added to the formulation, i.e., the amount of aluminum-silicon additives was 0%; the proportions of other raw materials and the particle size distribution of the aluminum-chromium slag matrix were the same as those of Example 1; the preparation method of the green body without additives was as follows: the binder was added to water and mixed to obtain a binder solution; wherein, the mass ratio of binder to water was 1:1; then the aluminum-chromium slag matrix was mixed with the binder solution to obtain a wet mixture; the wet mixture was placed in a mold and pressed under a pressure of 150 MPa to obtain a green body without additives.

[0053] Statistical results of the changes in compressive strength and apparent porosity of refractory materials under different heat treatment temperatures are as follows: Figure 2 , Figure 3 As shown. By Figure 2 and Figure 3 It can be seen that the green body prepared in Example 1 of the present invention has a room temperature compressive strength of 83.86 MPa after heat treatment at 200℃, which is 3.2 times that of the green body without additives (25.86 MPa); the apparent porosity decreased from 14.80% to 13.14%. This result shows that the aluminum-silicon composite additive can effectively optimize the green body structure during the curing stage, providing a more uniform and denser matrix for subsequent heat treatment. The green body prepared in Example 1 of the present invention maintains a strength of 21.71 MPa after heat treatment at 600℃, which is 4.1 times that of the green body without additives (5.26 MPa); the apparent porosity was suppressed from 17.80% to 15.33%. This result shows that the aluminum-silicon composite additive can effectively overcome the inherent "mid-temperature strength trough" of lignin sulfonate binders, which is the core breakthrough of the present invention. The green body prepared in Example 1 of this invention achieved a room temperature compressive strength of 104.43 MPa after heat treatment at 1000℃, with an apparent porosity reduced to 12.6%. Compared with the green body without additives (52.34 MPa, 15.01%), it achieved a synergistic strengthening effect of increasing strength by 99.5% and reducing porosity by 16.1%. These results indicate that the aluminum-silicon composite additive plays a role in curing reinforcement, mid-temperature support, and ceramicization reinforcement at 200℃, 600℃, and 1000℃, respectively, with the strength reaching a peak of 104.43 MPa at 1000℃.

[0054] (v) Effect of aluminum-silicon composite additives on chromium leaching of ceramicized refractories at different heat treatment temperatures The green bodies obtained by pressing and molding in step S3 of Example 1 of this invention were heat-treated at 200℃, 600℃, 800℃, and 1000℃, respectively, with a holding time of 6 hours for each temperature. The changes in chromium leaching of the refractory material under different heat treatment temperatures were studied, with a green body without additives used as a comparison. The formulation of the green body without additives was basically the same as that of Example 1, except that: no aluminum-silicon additives were added to the formulation, i.e., the amount of aluminum-silicon additives was 0%; the proportions of other raw materials and the particle size distribution of the aluminum-chromium slag matrix were the same as those of Example 1; the preparation method of the green body without additives was as follows: the binder was added to water and mixed to obtain a binder solution; wherein, the mass ratio of binder to water was 1:1; then the aluminum-chromium slag matrix was mixed with the binder solution to obtain a wet mixture; the wet mixture was placed in a mold and pressed and molded under a pressure of 150 MPa to obtain a green body without additives.

[0055] Statistical results of chromium leaching from refractory materials at different heat treatment temperatures are as follows: Figure 4 As shown. By Figure 4 It can be seen that for the unadulterated green body, the chromium leaching concentration decreases slowly with increasing temperature: 18.674 mg / L at 200℃, 18.612 mg / L at 400℃, 18.536 mg / L at 600℃, 18.212 mg / L at 800℃, and drops to 16.88 mg / L at 1000℃. The green body prepared in Example 1 of this invention has a chromium leaching concentration similar to that of the unadulterated green body in the range of 200-600℃ (200℃: 18.631 mg / L, 400℃: 18.623 mg / L, 600℃: 18.591 mg / L), but it drops significantly to 15.832 mg / L at 800℃, and further to 10.88 mg / L at 1000℃, which is lower than the hazardous waste identification standard limit (15 mg / L). This downward trend is highly synchronized with the significant ceramic densification process of refractory materials at 800-1000℃, proving that the stabilization of chromium is a natural result of microstructure reorganization and phase stabilization during the "carbon-free ceramicization" process.

[0056] In summary, the ceramicized refractory material prepared by this invention has excellent compressive strength, density, and resistance to slag erosion, and also has good environmental safety.

Claims

1. A high-strength ceramicized refractory material based on aluminum-chromium slag, characterized in that, It is prepared from the following raw materials in parts by weight: 92-97 parts of aluminum-chromium slag matrix, 3-8 parts of binder and aluminum-silicon composite additive, wherein the amount of aluminum-silicon composite additive is 2%-10% of the total mass of aluminum-chromium slag matrix and binder; wherein the binder is lignosulfonate; and the aluminum-silicon composite additive is a mixture of metallic aluminum powder and silicon powder.

2. The high-strength ceramicized refractory material based on aluminum-chromium slag according to claim 1, characterized in that, The mass ratio of aluminum powder to silicon powder in the aluminum-silicon composite additive is 1:(0.2~1).

3. The high-strength ceramicized refractory material based on aluminum-chromium slag according to claim 2, characterized in that, The mass ratio of aluminum powder to silicon powder in the aluminum-silicon composite additive is 1:0.5, the particle size of the aluminum powder is ≤45μm, and the particle size of the silicon powder is ≤45μm.

4. The high-strength ceramicized refractory material based on aluminum-chromium slag according to any one of claims 1 to 3, characterized in that, The aluminum-chromium slag matrix is ​​composed of the following particle size distribution by mass percentage: 25%–30% aluminum-chromium slag particles with a particle size of 5–3 mm, 20%–26% aluminum-chromium slag particles with a particle size of 3–1 mm, 10%–15% aluminum-chromium slag particles with a particle size of 1–0 mm, and 30%–35% aluminum-chromium slag fine powder with a particle size ≤0.088 mm.

5. The high-strength ceramicized refractory material based on aluminum-chromium slag according to claim 4, characterized in that, The lignosulfonate is at least one of calcium lignosulfonate, sodium lignosulfonate, and magnesium lignosulfonate.

6. The high-strength ceramicized refractory material based on aluminum-chromium slag according to claim 5, characterized in that, The chemical composition of the aluminum-chromium slag is: Al2O3 75-90wt%, Cr2O3 8-12wt%, SiO2 <3wt%, Fe2O3 <1wt%.

7. The method for preparing the high-strength ceramicized refractory material based on aluminum-chromium slag according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Add the binder to water, mix well, and obtain a binder solution; S2: Mix the aluminum-chromium slag matrix with the aluminum-silicon composite additive to obtain a dry mixture; add the binder solution to the dry mixture and mix well to obtain a wet mixture; S3: Press the wet mixture into a blank, and bake the blank at 150-250°C to obtain a cured blank; S4: The solidified preform is calcined at 800-1200℃ for 4-8 hours to obtain alumina-chromium slag-based high-strength ceramicized refractory material.

8. The preparation method according to claim 7, characterized in that, In step S4, the calcination process is carried out under an air or nitrogen atmosphere.

9. The preparation method according to claim 7, characterized in that, In step S1, the mass ratio of the binder to water is 1:(0.5 to 1:2); in step S3, the pressing pressure is 100-200 MPa, and the baking time is 6-24 hours.

10. The application of the aluminum-chromium slag-based high-strength ceramicized refractory material according to any one of claims 1 to 6 in the kiln lining.

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