Silica fume-free and powdering-free iron runner castable and use method thereof

Abstract

The invention discloses a silica fume-free pulverization-free iron runner castable and a use method thereof, and belongs to the field of unshaped refractory materials. The castable comprises the following components in percentage by mass: 62-65% of calcined brown aluminum oxide; 7-10% of silicon carbide with a particle size of 0.1-1 mm; 1-2% of ball pitch; 8-10% of alumina micro powder; 1.6-2% of pure calcium aluminate cement; 0.8%-1.2% of special carbon black; 7-10% of silicon carbide powder; 3.5 to 5.5% of silicon oxynitride superfine powder; 0.2 to 0.4 percent of boron carbide powder; 0.1%-0.16% of metal aluminum powder; 1-2% of metal silicon powder; 0.08 to 0.12 percent of explosion-proof fiber; and 0.1-0.2% of a dispersing agent. According to the castable, silica fume is prevented from being used, the adverse effect that the silica fume is introduced into a low melting phase is fundamentally eliminated, finally, the slag resistance and the scouring resistance are synchronously improved, the service life of an iron runner material is greatly prolonged, and the castable has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of unshaped refractory materials, specifically relating to a silica fume-free and pulverized iron trench castable and its application method. Background Technology

[0002] The trough is a crucial channel for molten iron to flow from the blast furnace to the ladle. It is subjected to intense erosion from molten iron at 1500℃ and slag over a long period. Currently, trough castables primarily use fused alumina as the main material. However, the smelting process of fused alumina inevitably leaves residual carbon that is difficult to remove, causing varying degrees of pulverization in the trough castable and affecting its service life. Furthermore, the impact zone, such as the iron drop point, suffers severe erosion from slag and iron, often leading to premature removal of the trough from service.

[0003] With the development of intensified smelting processes and the continuous decline in ore grade entering the furnace, higher performance requirements have been placed on iron trough castables. However, current iron trough castables still have the following problems: ① To ensure sufficient workability of the castable refractory for iron troughs, cement and silica fume (silica powder) are often unavoidably added simultaneously. At high temperatures, the castable matrix forms a large amount of low-melting-point calcium feldspar and calcium chalcopyrite, leading to a decrease in the material's resistance to slag erosion. Simultaneously, due to the addition of silica fume, although the hot flexural strength at 1400℃×1h is relatively high due to the formation of a large amount of mullite in the matrix after liquid-phase sintering, resulting in a matrix interpenetrating structure, the hot flexural strength at 1500℃×1h decreases to less than 1MPa as the temperature rises further and a large amount of liquid phase is generated.

[0004] ② To improve resistance to slag erosion, the silicon carbide and carbon content in the castable needs to be increased. However, the increase in silicon carbide and carbon content seriously affects the strength of the castable, resulting in a decrease in erosion resistance and making it difficult to improve the service life of the castable.

[0005] ③ Vanadium-titanium blast furnace slag is relatively viscous with weak scouring power but strong erosion power. Some vanadium-titanium blast furnaces often use ordinary ore to adjust the furnace ore, requiring the iron trough castable to have both excellent slag resistance and excellent scouring resistance. However, the technical approaches to these two aspects are contradictory.

[0006] Therefore, solving the long-standing industry problem of the difficulty in simultaneously achieving slag resistance and erosion resistance in iron trough castables; addressing the issue of residual carbon pulverization in iron trough castables; and improving the service life of iron trough castables to achieve synchronous erosion in the slag-iron impact zone have become important research topics. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a silica fume-free and pulverized iron trough castable and its application method, which simultaneously achieves good slag resistance and erosion resistance, thereby improving the service life of the iron trough castable.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A silica fume-free and powder-free iron trench castable is provided, the components of which are expressed as follows by mass percentage: Calcinated brown fused alumina 62-65%; Silicon carbide 0.1-1mm: 7~10%; 1-2% of spherical asphalt; Alumina micro powder 8~10%; Pure calcium aluminate cement: 1.6-2%; Specialty carbon black 0.8~1.2%; 7-10% silicon carbide powder; Silicon oxynitride ultrafine powder 3.5~5.5%; Boron carbide powder 0.2~0.4%; 0.1-0.16% metallic aluminum powder; 1-2% metallic silicon powder; Explosion-proof fiber content: 0.08~0.12%; Dispersant 0.1~0.2%; wherein: The silicon oxynitride ultrafine powder D 50 ≤2.5μm; the special carbon black is a submicron-sized material.

[0009] In the above scheme, the calcined brown corundum has a particle size of 0.2-8mm.

[0010] In the above scheme, the calcined brown corundum contains Al2O3 ≥ 95.3 wt% and C ≤ 0.04%.

[0011] In the above scheme, the calcined brown fused alumina is a non-powdered brown fused alumina obtained by calcining high-quality electrofused brown fused alumina at 1000-1050℃ for 8-10 hours after cooling with a 12-ton small agglomeration bag (which extends the cooling time by 40% compared to the ordinary 40-ton agglomeration bag, resulting in smaller and more uniform fused alumina phase crystals, better toughness, and better impact resistance, and can extend the life of iron trough castable by 5% under the same conditions).

[0012] In the above scheme, the silicon carbide 0.1-1mm has the following composition: SiC ≥ 98.5wt% and Fe2O3 ≤ 0.3wt%.

[0013] In the above scheme, the alumina micro powder has Al2O3 ≥ 99.5 wt%, Na2O ≤ 0.1 wt%, a fineness of d50 ≤ 1.2 micrometers, and the crystal diameter of the primary crystal is controlled at 0.45 μm. It has a thickness of 0.55μm, very stable activity, an α-phase conversion rate of over 95%, better water-reducing properties, good fluidity, resistance to molten iron, and good strength development.

[0014] In the above scheme, the particle size of the spherical asphalt is ≤1mm.

[0015] In the above scheme, the main chemical components of the pure calcium aluminate cement are 68.5-70.5wt% Al2O3 and 28.5-30.5wt% CaO; the pure calcium aluminate cement has high purity and contains almost no other impurities, which can effectively improve the low-temperature, medium-temperature and high-temperature strength and thermomechanical properties of cement.

[0016] In the above scheme, the particle size of the special carbon black is submicron, preferably the German-made N990R ​​type.

[0017] In the above scheme, the silicon carbide powder has a SiC content of ≥98% and a fineness of ≤74μm.

[0018] In the above scheme, the boron carbide powder has a B4C content of ≥94% and a fineness of ≤45μm.

[0019] In the above scheme, the aluminum powder is produced by nitrogen atomization process, with Al≥99% and fineness≤74um.

[0020] In the above scheme, the particle size of the metallic silicon powder is ≤45μm and the Si content is ≥98.5%.

[0021] In the above scheme, the silicon oxynitride ultrafine powder contains Si2N2O ≥ 92%. Its main crystalline phase, high-purity silicon oxynitride, possesses excellent oxidation resistance, slag resistance, iron resistance, and high-temperature direct bonding properties. The silicon oxynitride D is ball-milled for 84 hours. 50 The best water-reducing filling effect is achieved when the particle size is ≤2.5μm. If the particle size is too coarse, the water-reducing effect will decrease, and if the particle size is too fine, it will easily absorb moisture.

[0022] In the above scheme, the explosion-proof fiber is polypropylene explosion-proof fiber; preferably, it is 160-180℃ and has a length of 5.9-6.1mm.

[0023] In the above scheme, the dispersant is a spray mixture of polyacrylic acid liquid and alumina powder at a mass ratio of 1:3-1:4; wherein the polyacrylic acid has a molecular weight of 5000-12000 and is a highly efficient composite water-reducing agent with excellent water-reducing performance. At the same time, it is not prone to bleeding and has good stability, thus avoiding the expansion and cracking of the iron trough castable.

[0024] A method for using the above-mentioned silica fume-free and pulverized iron trough castable is provided, specifically: ≤4% water is added to the castable and stirred evenly. Preferably, the amount of water added is 3.8-3.9%.

[0025] This invention provides a silica fume-free and pulverized iron trough castable, abandoning the traditional system that uses silica fume as the main water-reducing and sintering aid. It constructs a novel synergistic system composed of highly active alumina micropowder, silicon oxynitride ultrafine powder, and special carbon black, and combines it with calcined corundum aggregate, ultimately achieving excellent slag resistance and erosion resistance simultaneously; wherein: Calcined brown fused alumina was chosen to remove the residual carbon hazard on the surface of the fused brown fused alumina aggregate through calcination, avoiding the pulverization of corundum upon contact with water caused by the presence of aluminum carbide in the fused alumina. This reduced the generation of microcracks between the aggregate and the matrix of the castable, thereby improving the castable's resistance to slag and iron erosion. At the same time, a large amount of highly active alumina micro powder was used to replace the dense fused alumina fine powder in the iron trough castable. This not only effectively avoided the risk of pulverization upon contact with water that might be introduced by the dense fused alumina fine powder, but also significantly improved the density and strength of the castable at both room temperature and high temperature, while also possessing excellent resistance to molten iron erosion.

[0026] However, the extensive use of highly active alumina micron powder significantly increases slurry viscosity, deteriorates workability, and requires more water. This invention discovers that silicon oxynitride ultrafine powder of a specific fineness exhibits excellent water-reducing and filling effects, effectively blocking alumina micron powder particles. Simultaneously, submicron-sized special carbon black deeply fills the gaps between the micron powder particles and encapsulates them. Together, these two components achieve physical water reduction and viscosity reduction, ensuring that the castable retains excellent rheological properties even with low water addition.

[0027] Furthermore, the silicon oxynitride ultrafine powder of this invention forms a direct bond of SiAlON phase at high temperatures. This solid-state sintering mechanism differs from the low-melting-point liquid-phase sintering produced by silica fume. The silicon oxynitride ultrafine powder of a specific fineness firmly bonds silicon carbide particles together, effectively improving the sintering bonding effect of silicon carbide. This significantly enhances the hot strength and structural stability of the castable at 1500℃, solving the long-standing technical challenge of simultaneously achieving high silicon carbide content, high strength, slag resistance, and resistance to molten iron erosion in iron trough castables. Simultaneously, since the castable contains no silica fume, the cement does not produce a low-melting-point phase at high temperatures, instead forming a high-viscosity, high-melting-point calcium hexaaluminate phase with the alumina micropowder, further preventing slag erosion and penetration.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a silica fume-free and powder-free iron trough castable. By using an innovative combination of "silicon oxynitride ultrafine powder + highly active alumina micro powder + special carbon black" to replace traditional silica fume, and combining it with calcined corundum aggregate, the adverse effects of silica fume introducing low-melting-point phases are fundamentally eliminated. This not only optimizes the rheological properties during construction and reduces the amount of water added, but also significantly improves the strength and density of the castable by forming a silron phase that directly combines with the high-melting-point phase of calcium hexaaluminate in the system. This avoids the problem of simultaneously achieving high strength, high slag resistance, and high resistance to molten iron erosion under high silicon carbide content. Furthermore, by combining spherical asphalt, pure calcium aluminate cement, boron carbide powder, metallic aluminum powder, metallic silicon powder, explosion-proof fiber, and dispersant, the slag resistance of the iron trough castable in harsh areas such as the iron drop point is improved by more than 30%, and it effectively resists the simultaneous erosion of slag and iron, greatly extending the service life of the iron trough material and showing broad application prospects. Detailed Implementation

[0029] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0030] In the following examples, the raw material specifications are as follows: The calcined brown fused alumina has a particle size of 0.2-8 mm. It is a non-powdered brown fused alumina obtained by calcining 12 tons of high-quality fused brown fused alumina cooled in a small bundle at 1000-1050℃ for 8 hours, with Al2O3 ≥ 95.3 wt% and C ≤ 0.04%.

[0031] The silicon carbide 0.1-1mm: SiC≥98.5wt%, Fe2O3≤0.3wt%.

[0032] The alumina micro powder has Al2O3 ≥ 99.5 wt% and Na2O ≤ 0.1 wt%, and its fineness is D. 50 The crystal size is ≤1.2 micrometers, the crystal diameter of the original crystal is controlled at around 0.5 μm, the crystal diameter fluctuation range is within 0.05 μm, the activity is very stable, and the α phase conversion rate reaches more than 95%.

[0033] The main chemical components of the pure calcium aluminate cement are 68.5-70.5 wt% Al2O3 and 28.5-30.5 wt% CaO, with almost no other impurities.

[0034] The special carbon black is of the German-made N990R ​​type.

[0035] The silicon carbide powder contains ≥98% SiC and has a fineness of ≤74µm.

[0036] The boron carbide powder has a B4C content of >94% and a fineness of ≤45μm.

[0037] The aluminum powder is produced by nitrogen atomization process, with Al≥99% and a fineness≤74um.

[0038] The silicon metal powder has a particle size ≤45μm and a Si content ≥98.5%.

[0039] The silicon oxynitride ultrafine powder contains Si2N2O ≥ 92%, D 50 ≤2.5μm.

[0040] The explosion-proof fiber is polypropylene explosion-proof fiber with a melting point of 170±10 ℃ and a length of 6 mm.

[0041] The dispersant is a spray mixture of polyacrylic acid liquid and alumina powder at a ratio of 1:3. The polyacrylic acid liquid is produced by Kao Corporation of Japan, with a molecular weight of 5000-12000 and excellent water-reducing properties.

[0042] The particle size of the spherical asphalt is ≤1mm.

[0043] Example 1 A silica fume-free and powder-free iron trench castable is provided, and the components and their mass percentages are as follows: Calcined brown corundum 62%; Silicon carbide 0.1-1mm: 9.42%; 2% of spherical asphalt; 9% alumina micro powder; Pure calcium aluminate cement 2%; Specialty carbon black 1.2%; 7% silicon carbide powder; Silicon oxynitride ultrafine powder 5.5%; Boron carbide powder 0.4%; 0.16% metallic aluminum powder; 1% metallic silicon powder; 0.12% explosion-proof fiber; Dispersant 0.2%.

[0044] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 3.8% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after the sample is formed, let it dry naturally for 24 h and then heat-treat it at 110 ℃ for 24 h to obtain a sample of iron trough castable without silica fume and without pulverization.

[0045] Comparative Example 1 A castable refractory for iron trenches is provided. The specific components, proportions and sample preparation methods are the same as in Example 1, except that: ordinary multiphase microcrystalline silicon nitride powder is used instead of silicon oxynitride ultrafine powder. The main crystalline phases of the ordinary multiphase microcrystalline silicon nitride powder are silicon nitride and silicon oxynitride, with Si≥45% and 13%≤N≤16%.

[0046] Comparative Example 2 A castable refractory for iron troughs is provided. The specific components, proportions and sample preparation methods are the same as in Example 1, except that silicon carbide powder replaces special carbon black and the silicon carbide powder content is increased to 8.2%.

[0047] Comparative Example 3 A castable refractory for iron trenches is provided. The specific components, proportions and sample preparation methods are the same as in Example 1, except that silicon carbide powder replaces silicon oxynitride ultrafine powder, and the silicon carbide powder content is increased to 12.5%.

[0048] The performance of the iron trough castable samples prepared in Example 1 and Comparative Examples 1-3 was tested, and the results are shown in Table 1. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (the same applies below).

[0049] Table 1. Comparison of performance test results of iron trough castable samples prepared in Example 1 and Comparative Examples 1-3

[0050] Example 2 A silica fume-free and powder-free iron trench castable is provided, and the components and their mass percentages are as follows: Calcined brown corundum 65%; Silicon carbide 0.1-1mm: 7%; 1% of spherical asphalt; 10% alumina micro powder; Pure calcium aluminate cement: 1.6%; Specialty carbon black 0.8%; Silicon carbide powder 9.37%; Silicon oxynitride ultrafine powder 3.5%; Boron carbide powder 0.2%; 0.1% metallic aluminum powder; 1.25% metallic silicon powder; Explosion-proof fiber 0.08%; Dispersant 0.1%.

[0051] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 3.9% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 h and then heat-treated at 110 ℃ for 24 h to obtain a sample of iron trough castable without silica fume and without pulverization.

[0052] The performance of the silica fume-free and pulverized iron trough castable samples prepared in this embodiment was tested, and the results are shown in Table 2. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (the same applies below).

[0053] Table 2. Performance test results of the silica fume-free and pulverized iron trough castable samples prepared in Example 2

[0054] Example 3 A silica fume-free and powder-free iron trench castable is provided, and the components and their mass percentages are as follows: Calcined brown corundum: 63.03%; Silicon carbide 0.1-1mm: 8.5%; 1.5% of spherical asphalt; 9% alumina micro powder; Pure calcium aluminate cement 1.8%; Specialty carbon black 1%; Silicon carbide powder 8.5%; Silicon oxynitride ultrafine powder 4.5%; Boron carbide powder 0.3%; 0.12% metallic aluminum powder; 1.5% metallic silicon powder; 0.1% explosion-proof fiber; Dispersant 0.15%.

[0055] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 3.9% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 h and then heat-treated at 110 ℃ for 24 h to obtain a sample of iron trough castable without silica fume and without pulverization.

[0056] The performance of the silica fume-free and pulverized iron trough castable samples prepared in this embodiment was tested, and the results are shown in Table 3. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (the same applies below).

[0057] Table 3. Performance test results of the silica fume-free and pulverized iron trough castable samples prepared in Example 3

[0058] Example 4 The components and their mass percentages for the silica fume-free and pulverized iron trench castable are as follows: Calcined brown corundum 63.5%; Silicon carbide 0.1-1mm: 10%; 1% of spherical asphalt; 8% alumina micro powder; Pure calcium aluminate cement: 1.6%; Specialty carbon black 0.8%; 10% silicon carbide powder; Silicon oxynitride ultrafine powder 3.5%; Boron carbide powder 0.21%; 0.12% metallic aluminum powder; 1% metallic silicon powder; 0.12% explosion-proof fiber; Dispersant 0.15%.

[0059] Weigh and mix all raw materials according to the above proportions; then add water (the mass of water is 3.9% of the total mass of all raw materials), stir evenly, and then vibrate to form the sample; after forming, the sample is naturally dried for 24 h and then heat-treated at 110 ℃ for 24 h to obtain a sample of iron trough castable without silica fume and without pulverization.

[0060] The performance of the silica fume-free and pulverized iron trough castable samples prepared in this embodiment was tested, and the results are shown in Table 4. The performance testing methods used were in accordance with current national or industry standards, and the test results are the average of three test results (the same applies below).

[0061] Table 4. Performance test results of the silica fume-free and pulverized iron trough castable samples prepared in Example 4

[0062] The above results indicate that the silica-free and pulverized iron trench castable of the present invention has the characteristics of low water addition, high high temperature strength, and good resistance to slag and iron erosion.

[0063] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A silica fume-free and pulverized iron trench castable, characterized in that, The components, expressed as a percentage by mass, are as follows: Calcinated brown fused alumina 62-65%; Silicon carbide 0.1-1mm: 7~10%; 1-2% of spherical asphalt; Alumina micro powder 8~10%; Pure calcium aluminate cement: 1.6-2%; Specialty carbon black 0.8~1.2%; 7-10% silicon carbide powder; Silicon oxynitride ultrafine powder 3.5~5.5%; Boron carbide powder 0.2~0.4%; 0.1-0.16% metallic aluminum powder; 1-2% metallic silicon powder; Explosion-proof fiber content: 0.08~0.12%; Dispersant 0.1~0.2%; wherein: The silicon oxynitride ultrafine powder D 50 ≤2.5μm; the special carbon black is a submicron-sized material.

2. The iron trough castable according to claim 1, characterized in that, The calcined brown corundum contains Al2O3 ≥ 95.3 wt% and C ≤ 0.04%.

3. The iron trough castable according to claim 1, characterized in that, The calcined brown corundum has a particle size of 0.2-8 mm.

4. The iron trough castable according to claim 1, characterized in that, The silicon carbide is 0.1-1mm thick: SiC ≥ 98.5wt%, Fe2O3 ≤ 0.3wt%; the particle size of the spherical asphalt is ≤ 1mm; the main chemical components of the pure calcium aluminate cement are Al2O3 68.5-70.5wt% and CaO 28.5-30.5wt%.

5. The iron trough castable according to claim 1, characterized in that, The alumina micro powder has an Al2O3 content of ≥99.5 wt% and a Na2O content of ≤0.1 wt%, with a fineness of d50 ≤1.2 micrometers and a crystal diameter of 0.45 μm in the primary crystals. At 0.55 μm, the α-phase conversion rate reaches over 95%.

6. The iron trough castable according to claim 1, characterized in that, The special carbon black is of the German-made N990R ​​type.

7. The iron trough castable according to claim 1, characterized in that, The silicon carbide powder has a SiC content of ≥98% and a fineness of ≤74μm; the boron carbide powder has a B4C content of ≥94% and a fineness of ≤45μm; the aluminum powder is produced by nitrogen atomization process, with Al ≥99% and a fineness of ≤74μm; the silicon powder has a particle size of ≤45μm and a Si content of ≥98.5%.

8. The iron trough castable according to claim 1, characterized in that, The silicon oxynitride ultrafine powder contains ≥92% Si2N2O.

9. The iron trough castable according to claim 1, characterized in that, The explosion-proof fiber is polypropylene explosion-proof fiber; the dispersant is a mixture of polyacrylic acid liquid and alumina powder by spraying at a mass ratio of 1:3-1:

4.

10. A method of using the silica fume-free and powder-free iron trench castable according to any one of claims 1-9, characterized in that, Specifically, ≤4% water is added to the castable and stirred until homogeneous.

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