An Al2O3-SiC-C refractory castable product and its preparation method

Abstract

The application belongs to the technical field of new refractory materials, and particularly relates to an Al2O3-SiC-C refractory castable product and a preparation method thereof. According to mass percentage, the raw material composition of the Al2O3-SiC-C refractory castable product comprises: aggregate 50-85%, matrix 6-35%, binding agent 1-10%, antioxidant 1-5%, additive 0.2-2%, and an additive agent accounting for 0.1-1% of the total mass of the above raw materials. The binding agent is light-burned magnesium oxide powder. The Al2O3-SiC-C refractory castable product has high strength, good slag erosion resistance and penetration resistance, and has the advantages of convenient construction, long construction time during pouring, low production energy consumption and the like.

Description

Technical Field

[0001] This invention belongs to the field of new refractory materials technology, specifically relating to an Al2O3-SiC-C refractory castable product and its preparation method. Background Technology

[0002] Al2O3-SiC-C refractory castables are mainly used in blast furnace tapping troughs. These troughs serve as channels for high-temperature molten iron and slag, and the castables are monolithic refractory materials designed to meet the requirements of tapping. With the development of modern blast furnaces towards larger scale and longer service life, the amount of iron tapped from the blast furnace tapping troughs has increased dramatically, placing more stringent demands on the refractory materials used in these troughs. The main development directions for tapping trough refractory materials have become: no introduction of impurities, strong oxidation resistance, strong erosion resistance, and long service life.

[0003] The type of binder significantly impacts the performance of iron trough refractories. This type of refractory castable requires excellent high-temperature mechanical properties, slag and erosion resistance, oxidation resistance, and thermal shock stability. Currently, calcium aluminate cement is the primary binder used in iron trough refractories. While using calcium aluminate cement as a binder results in high strength and easy molding of the refractory castable, it introduces CaO, which generates low-melting-point substances at high temperatures, directly affecting the high-temperature performance and slag erosion resistance of the refractories. Furthermore, the use of calcium aluminate cement increases water demand, leading to an increase in hydration products. During heating, these hydration products dehydrate and decompose, creating micropores within the structure and disrupting the hydration network.

[0004] Antioxidants also have a significant impact on this refractory castable. Currently, silicon powder and boron carbide are commonly used as antioxidants in this system of refractory castables. Boron carbide will generate a boron oxide liquid phase under high temperature conditions, reducing its high-temperature corrosion resistance. Silicon powder will generate silicon dioxide at high temperatures, which will be distributed on the surface of the castable, causing the internal silicon powder to lose its antioxidant effect, resulting in poor oxidation resistance of the silicon powder. Summary of the Invention

[0005] In view of the problems and shortcomings of the existing technology, the purpose of this invention is to provide an Al2O3-SiC-C refractory castable product and its preparation method.

[0006] To achieve the objectives of this invention, the technical solution adopted is as follows:

[0007] The first aspect of this invention provides an Al2O3-SiC-C refractory castable product, wherein the raw material composition of the Al2O3-SiC-C refractory castable, by mass percentage, is: 50%-85% aggregate, 6%-35% matrix, 1%-10% binder, 1%-5% antioxidant, 0.2%-2% additives, and an additional additive accounting for 0.1%-1% of the total mass of the above raw materials; the binder is lightly calcined magnesia powder.

[0008] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the antioxidant is passivated aluminum powder.

[0009] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the passivated aluminum powder is prepared by calcining aluminum powder at 500-620℃ for 1-20 hours and then cooling to obtain passivated aluminum powder. More preferably, the passivated aluminum powder is prepared by calcining aluminum powder at 500-620℃ for 5-20 hours and then cooling to obtain passivated aluminum powder. Most preferably, the passivated aluminum powder is prepared by calcining aluminum powder at 580℃ for 15 hours and then cooling to obtain passivated aluminum powder.

[0010] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the aggregate is at least one of corundum particles and silicon carbide particles. More preferably, the aggregate is both corundum particles and silicon carbide particles.

[0011] According to the above-mentioned Al2O3-SiC-C refractory castable product, preferably, the matrix is ​​at least one selected from corundum fine powder, silicon carbide fine powder, activated alumina micro powder, and carbon materials. More preferably, the matrix is ​​at least one selected from corundum fine powder, silicon carbide fine powder, activated alumina micro powder, and carbon materials.

[0012] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the additive is lactate; more preferably, the lactate is at least one of aluminum lactate, magnesium lactate, zinc lactate, and nickel lactate; most preferably, the lactate is aluminum lactate.

[0013] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the particle size of the carbon material is 1-2 mm, and the carbon material is asphalt, graphite, or carbon black. More preferably, the carbon material is carbon black.

[0014] According to the above-mentioned Al2O3-SiC-C refractory castable product, preferably, the admixture is a water-reducing agent; the water-reducing agent is a polycarboxylate water-reducing agent or a naphthalene-based water-reducing agent. More preferably, the water-reducing agent is a polycarboxylate water-reducing agent.

[0015] According to the above-mentioned Al2O3-SiC-C refractory castable product, preferably, the raw material composition of the Al2O3-SiC-C refractory castable, by mass percentage, is as follows: 50%-70% corundum particles, 1%-15% silicon carbide particles, 1%-10% fine corundum powder, 1%-10% fine silicon carbide powder, 3%-5% fine activated alumina powder, 1%-10% carbon materials, 1%-10% binder, 1%-5% antioxidant, 0.2%-2% additives, and an additional 0.1%-1% of the total mass of the above raw materials; the binder is lightly calcined magnesia powder.

[0016] According to the above-mentioned Al2O3-SiC-C refractory castable product, preferably, the raw material composition of the Al2O3-SiC-C refractory castable, by mass percentage, is as follows: 50%-70% corundum particles, 1%-15% silicon carbide particles, 1%-10% fine corundum powder, 1%-10% fine silicon carbide powder, 3%-5% fine activated alumina powder, 1%-5% carbon materials, 1%-7% binder, 2%-5% antioxidant, 0.2%-2% additives, and an additional 0.1%-1% of the total mass of the above raw materials as an admixture; the binder is lightly calcined magnesia powder.

[0017] According to the above-mentioned Al2O3-SiC-C refractory castable product, preferably, the raw material composition of the Al2O3-SiC-C refractory castable, by mass percentage, is as follows: 64.5% corundum particles, 8% silicon carbide particles, 4.4% fine corundum powder, 8% fine silicon carbide powder, 5% fine activated alumina powder, 3% carbon materials, 3% binder, 3.5% antioxidant, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials as an admixture; the binder is lightly calcined magnesia powder.

[0018] According to the Al2O3-SiC-C refractory castable product described above, preferably, the corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm mixed in a mass ratio of 5:5:5:2.

[0019] According to the Al2O3-SiC-C refractory castable product described above, preferably, the particle size of the silicon carbide particles is 0.1 to 1 mm.

[0020] According to the Al2O3-SiC-C refractory castable product described above, preferably, the particle size of the corundum fine powder is ≤0.045mm; the particle size of the silicon carbide fine powder is ≤0.075mm; the particle size of the activated alumina fine powder is 2-4μm; the particle size of the binder is 4-5μm; the particle size of the passivated aluminum powder is 0.048-0.11mm; the particle size of the additive is ≤0.075mm; and the particle size of the carbon material is 1-2mm.

[0021] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the corundum is one of brown corundum (Al2O3 ≥ 95.7% in brown corundum), white corundum (Al2O3 ≥ 97.5% in white corundum), or tabular corundum (Al2O3 ≥ 99% in tabular corundum). More preferably, the corundum is brown corundum.

[0022] According to the above-mentioned Al2O3-SiC-C refractory castable, preferably, the purity of the silicon carbide is ≥98.5%.

[0023] A second aspect of the present invention provides a method for preparing the Al2O3-SiC-C refractory castable product described in the first aspect above, comprising the following steps:

[0024] (1) Mix aggregates, matrix, binder, antioxidant, additives and admixtures evenly to obtain a mixture;

[0025] (2) Add water to the mixture prepared in step (1), stir and mix evenly to obtain a wet mixture;

[0026] (3) The wet mixture is cast, cured and dried to obtain a billet; the billet is calcined at 1150℃~1450℃ for 1~10h in a carbon atmosphere to obtain a refractory castable product.

[0027] Compared with the prior art, the positive and beneficial effects achieved by the present invention are as follows:

[0028] (1) Existing refractory castables mostly use silicon powder, boron carbide and other antioxidants. When silicon powder is used as an antioxidant, the addition of a high content of small particle size elemental silicon powder leads to an increase in the amount of low melting point composite silicate, which in turn reduces the castable's resistance to slag erosion and penetration. When boron carbide is used as an antioxidant, the addition of a high content of boron carbide leads to an increase in the amount of low viscosity boron-containing liquid phase generated in the castable, which reduces the castable's resistance to slag erosion and penetration. The Al2O3-SiC-C refractory castable of this invention uses passivated aluminum powder as an antioxidant. On the one hand, the passivation layer on the surface of the passivated aluminum powder can effectively prevent the aluminum powder from reacting with the free water in the castable to generate gas. On the other hand, the aluminum powder and the hydration products of lightly calcined magnesium oxide have a synergistic effect to generate dense magnesium aluminum hydrotalcite, which further prevents the hydration of aluminum powder, avoids the expansion of the green body, and improves the density of the castable, thereby improving the performance of the castable.

[0029] (2) The present invention calcines aluminum powder at 500-620℃ for 1-20 hours, and its surface is oxidized to form a dense aluminum oxide layer. After cooling, passivated aluminum powder is obtained. The passivated aluminum powder has the advantages of simple preparation process, relatively uniform coating layer, and mass production. It can also avoid the problem that the passivated aluminum powder is easy to clump when using aluminum sol coating to prepare passivated aluminum powder, which makes it difficult to disperse evenly during mixing and reduces the performance of refractory products. At the same time, it also avoids the problem that the passivated aluminum powder prepared by aluminum sol coating is easy to clump and needs to be crushed during use. However, the crushing process can easily cause the passivation layer to peel off, thus affecting the passivation effect.

[0030] (3) The refractory products of the present invention contain additives, preferably lactate. Lactate can limit the formation of Mg(OH)2, help control the hydration reaction rate of lightly burned magnesium oxide in the initial processing stage of the refractory products, and extend the construction time of casting.

[0031] (4) This invention uses lightly calcined magnesia powder as a binder to prepare refractory castables. At high temperatures, the lightly calcined magnesia powder can react with the active alumina micropowder in the matrix to generate magnesium aluminum spinel in situ, promoting the sintering and densification of the material and blocking further oxygen penetration. At the same time, the magnesium aluminum spinel can also absorb FeO and Fe2O3 in the steel slag to form a dense layer, preventing further penetration and greatly improving the refractory products' resistance to slag erosion and penetration. In addition, using lightly calcined magnesia powder as a binder can avoid the formation of the CaO-Al2O3-SiO2 eutectic phase during calcination. At the same time, lightly calcined magnesia can generate the MgO-Al2O3-SiO2 phase with a higher melting point and higher viscosity under high temperature conditions, making the refractory castable more resistant to oxidation, erosion and penetration, and greatly improving the service life of the refractory castable. Moreover, compared with calcium aluminate cement, a commonly used binder in castables, this invention uses lightly calcined magnesium oxide powder as a binder, which avoids the introduction of CaO into the castable. This solves the technical problem that the introduction of CaO into the castable when using calcium aluminate cement as a binder reduces the slag erosion resistance and permeability of refractory products.

[0032] (5) The Al2O3-SiC-C refractory castable of the present invention contains carbon material with a particle size of 1 to 2 mm. This carbon material is not easily wetted by molten steel and slag, has a small coefficient of thermal expansion and high thermal conductivity, which can significantly increase the thermal shock resistance and erosion resistance of the refractory product.

[0033] (6) The bulk density of the Al2O3-SiC-C refractory castable product of the present invention is 3.3-3.6 g / cm³. 3 The room temperature flexural strength reaches 3.1–26 MPa, the room temperature compressive strength reaches 69.1–145.2 MPa, the high temperature flexural strength reaches 1.1–12 MPa, and the erosion index reaches 3–24.1%. Therefore, the Al2O3-SiC-C refractory castable products of the present invention have high strength, good resistance to slag erosion and penetration, and also have the advantages of convenient construction, long construction time during casting, and low production energy consumption. Detailed Implementation

[0034] 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.

[0035] 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.

[0036] Example 1: Discussion of Antioxidant Types

[0037] To investigate the effect of the type of antioxidant in refractory castables on the properties of the prepared Al2O3-SiC-C refractory castables, this invention conducted Examples 1-1, 1-1, and 1-2. The specific details of Examples 1-1, 1-1, and 1-2 are as follows:

[0038] Example 1-1:

[0039] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 4.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon material with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0040] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0041] The specific steps for preparing the above-mentioned Al2O3-SiC-C refractory castable products are as follows:

[0042] (1) Mix corundum particles, silicon carbide particles, corundum fine powder, silicon carbide fine powder, activated alumina fine powder, carbon materials, binder, antioxidant, additives and admixtures evenly to obtain a mixture;

[0043] (2) Add water to the mixture prepared in step (1), the amount of water added is 4% of the total mass of the mixture, stir and mix evenly to obtain a wet mixture;

[0044] (3) The wet mixture is poured, cured and dried to obtain a billet. The billet is calcined at 1350°C for 3 hours in a carbon atmosphere to obtain a refractory castable product.

[0045] Comparative Example 1-1:

[0046] The content of Comparative Example 1-1 is basically the same as that of Example 1-1, except that the antioxidant is aluminum powder.

[0047] Comparative Examples 1-2:

[0048] The contents of Comparative Examples 1-2 are basically the same as those of Examples 1-1, except that the antioxidant is silicon powder.

[0049] The mechanical properties of refractory products prepared from the billets of Examples 1-1, 1-1, and 1-2 after calcination were tested. The testing methods were as follows: bulk density was tested according to GB / T 2999-2016; flexural strength at room temperature was tested according to GB / T 3001-2017; flexural strength at high temperature was tested according to GB / T 3002-2017; compressive strength at room temperature was tested according to GB / T 5072-2008; and erosion rate was tested using the static crucible method. The results of the mechanical property tests are shown in Table 1.

[0050] Table 1 shows the test results of the mechanical properties of the refractory castable products prepared in Examples 1-1, Comparative Example 1-1, and Comparative Example 1-2.

[0051]

[0052] As shown in Table 1, when unpassivated aluminum powder is used as an antioxidant, the prepared refractory products have low bulk density and poor mechanical properties. This is because the addition of aluminum powder causes significant expansion of the billet during curing, reducing its density. Therefore, the prepared refractory products have poor mechanical properties and erosion resistance. When silicon powder is used as an antioxidant, its presence increases the amount of low-melting-point composite silicates, thereby reducing the castable's resistance to slag erosion and penetration. Therefore, the prepared refractory products have poor erosion resistance and mechanical properties. The passivated aluminum powder of this invention, as an antioxidant for Al2O3-SiC-C refractory castables, can effectively overcome the shortcomings of using unpassivated aluminum powder and silicon powder as antioxidants. The prepared Al2O3-SiC-C refractory castable products have excellent erosion resistance and mechanical properties.

[0053] Example 2: Discussion on the Dosage of Passivating Aluminum Powder

[0054] To investigate the effect of the amount of passivating aluminum powder on the properties of the prepared Al2O3-SiC-C refractory castable, Examples 2-1 to 2-4 and Comparative Example 2-1 were conducted. The specific details of Examples 2-1 to 2-4 and Comparative Example 2-1 are as follows:

[0055] Example 2-1:

[0056] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 6.9% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 1% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and additional admixtures accounting for 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0057] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0058] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0059] Example 2-2:

[0060] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 5.9% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 2% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0061] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0062] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0063] Examples 2-3:

[0064] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 3.9% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 4% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0065] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0066] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0067] Examples 2-4:

[0068] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 1-0 mm, 2.9% fine corundum powder with a particle size ≤0.074 mm, 8% fine silicon carbide powder with a particle size ≤0.045 mm, 5% fine activated alumina powder with a particle size ≤0.045 mm, 3% carbon materials with a particle size of 1-2 mm, 3% binder with a particle size of 4-5 μm, 5% antioxidant with a particle size of 0.048-0.11 mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0069] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0070] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0071] Comparative Example 2-1:

[0072] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 1-0 mm, 1.9% fine corundum powder with a particle size ≤0.074 mm, 8% fine silicon carbide powder with a particle size ≤0.045 mm, 5% fine activated alumina powder with a particle size ≤0.045 mm, 3% carbon materials with a particle size of 1-2 mm, 3% binder with a particle size of 4-5 μm, 6% antioxidant with a particle size of 0.048-0.11 mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials as admixtures. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0073] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0074] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0075] The mechanical properties of the refractory products prepared after calcination of the billets from Examples 2-1 to 2-4 and Comparative Example 2-1 were tested (the testing method was the same as in Example 1). The test results are shown in Table 2.

[0076] Table 2 shows the test results of the mechanical properties of the refractory castable products prepared in Examples 2-1 to 2-4 and Comparative Example 2-1.

[0077]

[0078] As shown in Table 2, with the increase of the amount of antioxidant passivating aluminum powder, the erosion rate of the refractory castable products shows a trend of first decreasing and then increasing. When the content of antioxidant passivating aluminum powder reaches 3.5%, the erosion rate of the prepared refractory products reaches the lowest value, and the mechanical properties reach the optimal value. Further increasing the amount of antioxidant passivating aluminum powder will increase the expansion degree of the material, increase the erosion rate of the refractory products, and cause the mechanical properties to decrease. Therefore, the preferred content of antioxidant passivating aluminum powder is 1%-5%; more preferably 2%-5%, and most preferably 3.5%.

[0079] Example 3: Discussion of Binder Types

[0080] To investigate the effect of binder type on the properties of the prepared Al2O3-SiC-C refractory castable, comparative example 3-1 was conducted in this invention.

[0081] Comparative Example 3-1:

[0082] The content of Comparative Example 3-1 is the same as that of Example 1-1, except that the binder is calcium aluminate cement.

[0083] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0084] The mechanical properties of the refractory billets prepared in Examples 1-1 and 3-1 after calcination were tested, and the test results are shown in Table 3.

[0085] Table 3 shows the test results of the mechanical properties of the refractory castable products prepared in Examples 1-1 and Comparative Example 3-1.

[0086]

[0087] As shown in Table 3, although using calcium aluminate cement as a binder gives the castable high mechanical properties, calcium aluminate also introduces CaO, which, during calcination, forms a CaO-Al2O3-SiO2 eutectic phase, affecting its erosion resistance. Conversely, using lightly calcined magnesia as a binder, under high-temperature conditions, can produce a MgO-Al2O3-SiO2 phase with a higher melting point and higher viscosity, resulting in better oxidation resistance, erosion resistance, and impermeability resistance of the refractory castable, greatly improving its service life.

[0088] Example 4: Discussion on the Dosage of Binder

[0089] To investigate the effect of binder dosage on the properties of the prepared Al2O3-SiC-C refractory castables, Examples 4-1 to 4-4 and Comparative Example 4-1 were conducted. The specific details of Examples 4-1 to 4-4 and Comparative Example 4-1 are as follows:

[0090] Example 4-1:

[0091] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 6.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 1% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0092] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0093] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0094] Example 4-2:

[0095] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 2.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 5% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0096] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0097] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0098] Example 4-3:

[0099] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 0.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 7% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0100] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0101] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0102] Example 4-4:

[0103] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 8% silicon carbide fine powder with a particle size ≤0.045mm, 2.4% activated alumina fine powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 10% binder with a particle size of 4-5μm, and [missing information - likely a specific component or component].

[0104] The raw materials contain 3.5% antioxidant and 0.6% additives, plus an additional additive accounting for 0.15% of the total mass of the above raw materials. The corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is a polycarboxylate water-reducing agent. The antioxidant is passivated aluminum powder, and the passivated aluminum powder is prepared by calcining aluminum powder at 500–620°C for 1–20 hours and then cooling it to obtain passivated aluminum powder; preferably, the aluminum powder is calcined at 580°C for 15 hours and then cooled to obtain passivated aluminum powder.

[0105] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0106] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0107] Comparative Example 4-1:

[0108] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 8% silicon carbide fine powder with a particle size ≤0.045mm, 0.4% activated alumina fine powder with a particle size ≤0.045mm, 3% carbon materials with a particle size of 1-2mm, 12% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0109] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0110] The mechanical properties of the refractory products prepared after calcination of the billets of Examples 4-1 to 4-4 and Comparative Example 4-1 were tested, and the test results are shown in Table 4.

[0111] Table 4 shows the test results of the mechanical properties of the refractory castable products prepared in Examples 4-1 to 4-4 and Comparative Example 4-1.

[0112]

[0113] As shown in Table 4, the erosion resistance first increases and then decreases with the increase of the amount of light-burned magnesia powder in the binder. This is because excessive addition of light-burned magnesia powder causes significant volume expansion of the castable, reducing its density and thus affecting its erosion resistance. Therefore, the preferred amount of light-burned magnesia powder in the binder is 1%-10%, more preferably 1%-7%, and most preferably 3%.

[0114] Example 5: Discussion on the Dosage of Carbon Materials

[0115] To investigate the effect of carbon material content on the properties of the prepared Al2O3-SiC-C refractory castables, Examples 5-1 to 5-4 and Comparative Example 5-1 were conducted. The specific details of Examples 5-1 to 5-4 and Comparative Example 5-1 are as follows:

[0116] Example 5-1:

[0117] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 6.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 1% carbon material with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and additional admixtures accounting for 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0118] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0119] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0120] Example 5-2:

[0121] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 2.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 5% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials as an admixture. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0122] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0123] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0124] Example 5-3:

[0125] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 0.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 7% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0126] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0127] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0128] Example 5-4:

[0129] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 8% silicon carbide fine powder with a particle size ≤0.045mm, 2.4% activated alumina fine powder with a particle size ≤0.045mm, 10% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials. Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0130] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0131] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0132] Comparative Example 5-1:

[0133] An Al2O3-SiC-C refractory castable product, by mass percentage, comprises the following raw material composition: 64.5% corundum particles, 8% silicon carbide particles with a particle size of 0-1mm, 7.4% fine corundum powder with a particle size ≤0.074mm, 8% fine silicon carbide powder with a particle size ≤0.045mm, 5% fine activated alumina powder with a particle size ≤0.045mm, 0% carbon materials with a particle size of 1-2mm, 3% binder with a particle size of 4-5μm, 3.5% antioxidant with a particle size of 0.048-0.11mm, 0.6% additives, and an additional 0.15% of the total mass of the above raw materials.

[0134] Wherein, the corundum is brown corundum, the binder is lightly calcined magnesium oxide powder, the carbon material is carbon black, the additive is aluminum lactate, and the water-reducing agent is polycarboxylate water-reducing agent; the antioxidant is passivated aluminum powder, and the method for preparing the passivated aluminum powder is as follows: calcining aluminum powder at 500-620℃ for 1-20 hours, and then cooling to obtain passivated aluminum powder; preferably, calcining aluminum powder at 580℃ for 15 hours, and then cooling to obtain passivated aluminum powder.

[0135] The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:2.

[0136] The preparation method of the above Al2O3-SiC-C refractory castable products is the same as that in Examples 1-1.

[0137] The mechanical properties of the refractory billets prepared in Examples 5-1 to 5-4 and Comparative Example 5-1 after calcination were tested, and the test results are shown in Table 5.

[0138] Table 5 shows the test results of the mechanical properties of the refractory castable products prepared in Examples 5-1 to 5-4 and Comparative Example 5-1.

[0139]

[0140] Table 5 shows that adding carbon materials can improve the room temperature and high temperature mechanical properties and slag erosion resistance of castables. With increasing carbon material content, the room temperature and high temperature mechanical properties and slag erosion resistance of the castables first increase and then decrease. Because carbon materials have poor wettability, excessive addition can lead to difficulties in casting and affect its operational performance. Furthermore, carbon can seep into the molten iron during use, reducing the purity of the tapped iron. Therefore, the optimal addition amount of carbon materials is preferably 3%.

[0141] Example 6: Exploration of Calcination Gas Atmosphere

[0142] To investigate the effect of the calcination gas atmosphere on the properties of the prepared Al2O3-SiC-C refractory castable, comparative examples 6-1 and 6-2 were conducted in this invention.

[0143] Comparative Example 6-1:

[0144] The content of Comparative Example 6-1 is basically the same as that of Example 1-1, except that the preparation method of silicon carbide-magnesium aluminum spinel refractory products is different.

[0145] The preparation method of Al2O3-SiC-C refractory castable in this embodiment includes the following specific steps:

[0146] (1) Mix corundum particles, silicon carbide particles, corundum fine powder, silicon carbide fine powder, activated alumina fine powder, carbon-containing fine powder, binder, antioxidant, additives and admixtures evenly to obtain a mixture;

[0147] (2) Add water to the mixture prepared in step (1), the amount of water added is 4% of the total mass of the mixture, stir and mix evenly to obtain a wet mixture;

[0148] (3) The wet mixture is poured, cured and dried to obtain a billet. The billet is calcined in air at 1350°C for 3 hours to obtain a refractory castable product.

[0149] The mechanical properties of the refractory billet prepared in Comparative Example 6-1 after calcination were tested, and the test results are shown in Table 6.

[0150] Table 6 shows the test results of the mechanical properties of the refractory castable products prepared in Examples 1-1 and Comparative Example 6-1.

[0151]

[0152] Table 6 shows that samples fired in a carbon-embedded atmosphere exhibit superior physical properties and slag erosion resistance compared to samples fired in an air atmosphere. This is because in an air atmosphere, carbon materials undergo oxidation, generating gas and forming pores, leading to an increased apparent porosity and reduced physical properties of the castable. Simultaneously, molten slag more easily penetrates the material, causing spalling and other phenomena during use, severely impacting its service life. In a carbon-embedded atmosphere, the carbon powder covering the material surface is preferentially oxidized, effectively reducing the oxidation of antioxidants within the material during sintering, thereby improving the service life of the castable.

[0153] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may use the above technical content as inspiration to make changes or modifications. These are equivalent embodiments with variations. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical concept of the present invention still fall within the protection scope of the claims of the present invention.

Claims

1. An Al2O3-SiC-C refractory castable product, characterized in that, The raw material composition of the Al2O3-SiC-C refractory castable, by mass percentage, is as follows: 50%–70% corundum particles, 1%–15% silicon carbide particles, 1%–10% fine corundum powder, 1%–10% fine silicon carbide powder, 3%–5% activated alumina micro powder, 1%–10% carbon materials, 1%–10% binder, 1%–5% antioxidant, 0.2%–2% additives, and an additional 0.1%–1% of the total mass of the above raw materials as an additive; the binder is lightly calcined magnesium oxide powder; the antioxidant is passivated aluminum powder; the passivated aluminum powder is prepared by calcining aluminum powder at 500–620℃ for 1–20 h, and then cooling to obtain passivated aluminum powder; the additive is lactate.

2. The Al2O3-SiC-C refractory castable product according to claim 1, characterized in that, The carbon material is asphalt, graphite, or carbon black; the admixture is a water-reducing agent.

3. The Al2O3-SiC-C refractory castable product according to claim 2, characterized in that, The lactate is at least one of aluminum lactate, magnesium lactate, zinc lactate, and nickel lactate; the particle size of the carbon material is 1-2 mm; and the water-reducing agent is a polycarboxylate water-reducing agent or a naphthalene-based water-reducing agent.

4. The Al2O3-SiC-C refractory castable product according to claim 3, characterized in that, The corundum particles are composed of corundum particles with a particle size of 5-8 mm, corundum particles with a particle size of 3-5 mm, corundum particles with a particle size of 1-3 mm, and corundum particles with a particle size of 0.1-1 mm in a mass ratio of 5:5:5:

2.

5. A method for preparing an Al2O3-SiC-C refractory castable product according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Mix the aggregate, matrix, binder, antioxidant, additives and admixtures evenly to obtain a mixture; (2) Add water to the mixture prepared in step (1), stir and mix evenly to obtain a wet mixture; (3) The wet mixture is cast, cured and dried to obtain a billet; the billet is calcined at 1150℃~1450℃ for 1~10h in a carbon atmosphere to obtain a refractory castable product.

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