Cast small blast furnace iron notch refractory castable and its preparation method

Abstract

The application provides a cast small blast furnace runner refractory castable, which comprises the following raw materials: bauxite, brown corundum, nano rare earth oxide, active alumina, silicon carbide, metallic silicon, a dispersing agent, an antioxidant, carbon nanotube fibers and alumina fibers; and a preparation method, which comprises the following steps: mixing and stirring the bauxite, brown corundum, nano rare earth oxide, active alumina, silicon carbide, metallic silicon, dispersing agent, antioxidant, carbon nanotube fibers and alumina fibers to obtain a mixture; adding water to the mixture and stirring to obtain a slurry; pouring the slurry into a mold, performing vibration casting, demolding, drying, heat preservation and cooling to obtain the cast small blast furnace runner refractory castable. The refractory castable has good mechanical properties and slag resistance.

Description

Technical Field

[0001] This invention relates to a refractory castable for blast furnace tapping troughs, and more particularly to a refractory castable for tapping troughs of small casting blast furnaces and its preparation method. Background Technology

[0002] Improving the performance of iron trough material is of considerable significance, whether it is to reduce the consumption of castable refractory per ton of iron to obtain greater economic benefits or to reduce the use of polluting raw materials to obtain greater social benefits.

[0003] The tapping trough is an important component of the blast furnace ironmaking system, with the main tapping trough being the most crucial. It transports a mixture of high-temperature molten iron and slag away from the blast furnace. Upon reaching the end of the main tapping trough, this mixture separates into an upper layer of slag and a lower layer of molten iron due to differences in density. At this point, the molten iron flows out from below the slag baffle and into the branch tapping trough, while the molten slag flows into the slag trough from above the slag baffle.

[0004] The blast furnace tapping trough is the main area where refractory materials are consumed in the ironmaking process. In the casting of small blast furnaces, silicon is generally added outside the furnace, resulting in a high silicon dioxide content in the molten iron. The silicon dioxide in the iron slag reacts with the carbon in the molten iron to produce carbon monoxide. The carbon monoxide oxidizes the silicon carbide in the trough material, while the carbon can reduce the alumina in the trough material, leading to corrosion of the trough material. However, the blast furnace for pig iron casting is small in volume and is generally designed with a single tapping spout, with an iron flow time of up to 120 days. Therefore, the performance requirements for blast furnace tapping castables are relatively high.

[0005] Chinese patent CN114163254A discloses a blast furnace tapping trough castable, which, by weight, comprises: 20-30 parts bauxite particles, 30-40 parts brown corundum, 10-25 parts silicon carbide, 5-10 parts alumina micro powder, 1-4 parts high-alumina cement, 1-4 parts carbon, 0-3 parts calcium nitride fine powder, 0.1-0.5 parts dispersant, 0.1-1 part antioxidant, and 4.5-4.8 parts water. The resulting blast furnace tapping trough exhibits poor compressive strength and erosion resistance.

[0006] Therefore, there is an urgent need to develop a blast furnace tapping trough castable with high compressive strength and good erosion resistance. Summary of the Invention

[0007] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a refractory castable for the tapping trough of a small blast furnace and its preparation method, so as to solve the problem of poor erosion resistance of the existing blast furnace tapping trough.

[0008] To achieve the above and other related objectives, the first aspect of the present invention provides a refractory castable for the tapping trough of a small blast furnace, the refractory castable comprising the following raw materials in parts by weight: 40-50 parts of bauxite, 10-20 parts of brown corundum, 10-15 parts of nano-rare earth oxides, 5-10 parts of activated alumina, 5-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0009] A second aspect of this invention provides a method for preparing a refractory castable for the tapping trough of a small blast furnace, comprising the following steps:

[0010] (1) Mix and stir alumina, brown corundum, nano rare earth oxides, activated alumina, silicon carbide, metallic silicon, dispersant, antioxidant, carbon nanotube fiber and alumina fiber to obtain a mixture;

[0011] (2) Add water to the mixture obtained in step (1), mix to obtain slurry, pour the slurry into the mold, pour and vibrate to form, demold, cure, dry, keep warm and cool to obtain the final product.

[0012] As described above, the refractory castable for tapping troughs of small blast furnaces of the present invention and its preparation method have the following beneficial effects:

[0013] (1) The refractory castable for the tapping trough of the small blast furnace of the present invention introduces a variety of raw materials, including bauxite, brown corundum, nano rare earth oxides, active alumina, silicon carbide, metallic silicon, dispersant, antioxidant, carbon nanotube fiber and alumina fiber. The combination of these raw materials results in high compressive strength and flexural strength, and a small permanent linear change rate during heating. Therefore, the product has a long service life, low melting rate, strong oxidation resistance and high thermal shock stability.

[0014] (2) The nano-rare earth oxides added to the refractory castable for tapping trough of the small blast furnace of the present invention can improve the crystallization state of the main crystalline phase in the refractory castable for tapping trough, reduce the defects therein, thereby increasing its chemical stability and making the refractory castable for tapping trough have strong oxidation resistance; carbon nanotubes are tubular nanomaterials composed of carbon atoms, which have extremely high strength and effectively enhance the high temperature crack resistance of the material; alumina fibers are added to the material in a certain proportion, which can increase the strength, reduce the linear change after firing, and enhance the high temperature crack resistance. Detailed Implementation

[0015] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. Those skilled in the art can easily understand other advantages and effects of this invention from the content disclosed in this specification.

[0016] The first aspect of this invention is to provide a refractory castable for the tapping trough of a small blast furnace, the refractory castable comprising the following raw materials in parts by weight: 40-50 parts of bauxite, 10-20 parts of brown corundum, 10-15 parts of nano-rare earth oxides, 5-10 parts of activated alumina, 5-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0017] This invention introduces a combination of bauxite, brown corundum, nano-rare earth oxides, activated alumina, silicon carbide, metallic silicon, dispersants, antioxidants, carbon nanotube fibers, and alumina fibers. This results in refractory castables for small blast furnace tapholes exhibiting high compressive and flexural strength, low permanent linear shrinkage during heating, and consequently, a long service life, low melting rate, strong oxidation resistance, and high thermal shock stability. Furthermore, the nano-rare earth oxides improve the crystallization state of the main crystalline phases in the taphole refractory castables, reducing defects and increasing chemical stability, thus enhancing its oxidation resistance. The carbon nanotube fibers and alumina fibers possess high toughness and stiffness, allowing them to overlap within the taphole refractory castables, significantly improving its explosion-proof performance. Antioxidants are oxidized before C and SiC. The oxidation products expand in volume, making the castable more compact, or forming glassy substances that block the pores in the castable, reducing the amount of oxygen that can penetrate further into the castable, thereby slowing down the oxidation process of C and SiC in the castable.

[0018] In some embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 40-50 parts of bauxite, 10-20 parts of brown corundum, 10-15 parts of nano-rare earth oxides, 5-10 parts of activated alumina, 5-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0019] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 40-43 parts of bauxite, 10-13 parts of brown corundum, 10-12 parts of nano-rare earth oxides, 5-8 parts of activated alumina, 5-8 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0020] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 43-46 parts of bauxite, 13-17 parts of brown corundum, 12-15 parts of nano-rare earth oxides, 8-10 parts of activated alumina, 8-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0021] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 46-50 parts of bauxite, 17-20 parts of brown corundum, 12-15 parts of nano-rare earth oxides, 8-10 parts of activated alumina, 8-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0022] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 40 parts of bauxite, 10 parts of brown corundum, 10 parts of nano rare earth oxides, 5 parts of activated alumina, 5 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0023] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 43 parts bauxite, 13 parts brown corundum, 12 parts nano rare earth oxides, 8 parts activated alumina, 8 parts silicon carbide, 2-3 parts metallic silicon, 3-5 parts dispersant, 3-5 parts antioxidant, 3-5 parts carbon nanotube fiber, and 3-5 parts alumina fiber.

[0024] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 46 parts of bauxite, 17 parts of brown corundum, 15 parts of nano rare earth oxides, 10 parts of activated alumina, 10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0025] In some specific embodiments of the present invention, the refractory castable comprises the following raw materials in parts by weight: 50 parts of bauxite, 20 parts of brown corundum, 10-15 parts of nano-rare earth oxides, 5-10 parts of activated alumina, 5-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber.

[0026] In some specific embodiments, the dispersant is at least one of sodium hexametaphosphate and sodium tripolyphosphate; specifically, the dispersant is composed of sodium hexametaphosphate and sodium tripolyphosphate; more specifically, the dispersant is composed of sodium hexametaphosphate and sodium tripolyphosphate in a mass ratio of (1-2):(2-5);

[0027] The nano-rare earth oxide is at least one of nano-cerium dioxide and nano-lanthanum oxide; specifically, the nano-rare earth oxide is composed of nano-cerium dioxide and nano-lanthanum oxide; more specifically, the nano-rare earth oxide is composed of nano-cerium dioxide and nano-lanthanum oxide in a mass ratio of (5-7):(3-5);

[0028] The antioxidant is at least one of metallic silicon powder and boron carbide; specifically, the antioxidant is composed of metallic silicon powder and boron carbide; more specifically, the antioxidant is composed of metallic silicon powder and boron carbide in a mass ratio of (3-5):(1-3);

[0029] The brown fused alumina is fused brown fused alumina; specifically, the fused brown fused alumina is at least one of fused brown fused alumina particles and fused brown fused alumina fine powder; specifically, the fused brown fused alumina is composed of fused brown fused alumina particles and fused brown fused alumina fine powder; more specifically, the fused brown fused alumina is composed of fused brown fused alumina particles and fused brown fused alumina fine powder in a mass ratio of (2-4):(1-2);

[0030] The silicon carbide is at least one of silicon carbide particles and silicon carbide fine powder; specifically, the silicon carbide is composed of silicon carbide particles and silicon carbide fine powder; specifically, the silicon carbide is composed of silicon carbide particles and silicon carbide fine powder in a mass ratio of (1-3):(3-9); the particle size of the silicon carbide fine powder is 300-325 mesh.

[0031] The carbon nanotube fibers have a diameter of 2-20 nm and a single filament length of 10-150 mm.

[0032] The alumina fibers have a diameter of 2-20 μm and a single filament length of 10-150 mm;

[0033] The particle size of the activated alumina is less than 2 μm.

[0034] In some specific embodiments, the average erosion depth of the refractory castable in the slag resistance test is ≤5mm; the compressive strength of the refractory castable is >54MPa; the flexural strength of the refractory castable is ≥12MPa; and the permanent linear change rate of the refractory castable is ≤0.5.

[0035] In some preferred embodiments, the average erosion depth of the refractory castable in the slag resistance test is 3-5 mm; the compressive strength of the refractory castable is 54.3-55.7 MPa; the flexural strength of the refractory castable is 12-14 MPa; and the permanent linear change rate of the refractory castable is 0.3-0.5.

[0036] In some preferred embodiments, the bauxite contains ≥88% Al2O3; the bauxite has a particle size of at least one of 5-8 mm; specifically, the particle size distribution of the bauxite is 1-3 mm 30-50 wt%, 3-5 mm 20-30 wt%, and 5-8 mm 25-30 wt%.

[0037] Secondly, the present invention provides a method for preparing refractory castable for tapping troughs of small blast furnaces, comprising the following steps:

[0038] (1) Mix and stir alumina, brown corundum, nano rare earth oxides, activated alumina, silicon carbide, metallic silicon, dispersant, antioxidant, carbon nanotube fiber and alumina fiber to obtain a mixture;

[0039] (2) Add water to the mixture obtained in step (1), mix to obtain slurry, pour the slurry into the mold, pour and vibrate to form, demold, cure, dry, keep warm and cool to obtain the final product.

[0040] In some embodiments of the present invention, the weight of water in step (2) is 4.0-4.2% of the total amount of the mixture; and / or, the method of adding water is to first add 80-85% water, stir evenly, then add 15-20% water, and stir again.

[0041] In some embodiments of the present invention, step (1) mixing is carried out in a mixer at a mixing rate of 120-230 r / min.

[0042] In some embodiments of the present invention, the mixing time in step (2) is 180-300s.

[0043] In some embodiments of the present invention, the drying temperature in step (2) is 105-115°C and the drying time is 24 hours.

[0044] In some embodiments of the present invention, the heat preservation temperature in step (2) is 1445-1455℃, and the heat preservation time is 3-5h.

[0045] The present invention will be further illustrated by the following examples, but these examples do not limit the scope of the invention.

[0046] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, equipment, and materials similar to or equivalent to those described, used, and materials in the embodiments of this invention may be used to implement this invention.

[0047] The specifications and manufacturers of the raw materials used in this invention are as follows:

[0048] The carbon nanotube fiber of this invention is commercially available, manufactured by Jiangxi Jianglan Pure Biological Reagent Co., Ltd., and its model number is JLC-R10140.

[0049] The alumina fiber of this invention is commercially available, manufactured by Beijing Bioplore Biotechnology Co., Ltd., and its model name is Bioplore.

[0050] The silicon carbide particles of this invention have a particle size of 0-1 mm and a SiC content of ≥98%.

[0051] The average particle size of the silicon carbide fine powder of the present invention is 325 mesh.

[0052] The fused brown fused alumina of this invention contains ≥95wt% Al2O3 and ≤0.5wt% Fe2O3; the particle size of the fine powder is 180-200 mesh. The particle size of the fused brown fused alumina particles is 1-2 mm.

[0053] The activated alumina of this invention has a particle size of less than 2 μm and is commercially available.

[0054] Table 1. Raw material composition ratio of refractory castable for tapping troughs of small blast furnaces in Examples 1-3.

[0055] bauxite 40 45 50 Brown fused alumina 20 10 10 Nano rare earth oxides 5 13 10 Activated alumina 10 8 6 silicon carbide 6 5 5 Metallic silicon 2 2 2 dispersant 5 5 5 antioxidants 5 5 5 carbon nanotube fibers 5 5 5 alumina fiber 5 5 5

[0056] Example 1

[0057] The raw material composition of the refractory castable for the tapping trough of the small blast furnace in this embodiment is shown in Table 1. The antioxidant is boron carbide; the dispersant is sodium hexametaphosphate; the nano-rare earth oxide is composed of nano-cerium dioxide and nano-lanthanum oxide in a mass ratio of 6:4; the brown fused alumina is fused brown fused alumina; the silicon carbide is composed of silicon carbide particles and silicon carbide fine powder in a mass ratio of 1:3, the silicon carbide particles have a particle size of 0-1 mm, SiC ≥ 98%, and the average particle size of the silicon carbide fine powder is 325 mesh; the fused brown fused alumina is composed of fused brown fused alumina particles and fused brown fused alumina fine powder in a mass ratio of 2:1; the bauxite has a particle size distribution of 45% for 1-3 mm, 25% for 3-5 mm, and 30% for 5-8 mm.

[0058] The preparation method of the refractory castable for the tapping trough of the small blast furnace in this embodiment includes the following steps:

[0059] (1) Alumina, brown corundum, nano rare earth oxides, activated alumina, silicon carbide, metallic silicon, dispersant, antioxidant, carbon nanotube fiber and alumina fiber are mixed and stirred to obtain a mixture; the mixing is carried out in a mixer at a stirring rate of 150 r / min.

[0060] (2) Add water to the mixture obtained in step (1), mix for 250 seconds to obtain a slurry, pour the slurry into a 40mm×40mm×160mm triple mold, vibrate and cast on a vibrating table, demold after 24 hours of natural curing, place in an oven and dry at 110℃ for 24 hours, then fire at 1450℃ for 3 hours, and cool with the furnace; after cooling, the product is obtained. The method of adding water is to first add 80% water and stir evenly, then add 20% water and stir again, the weight of water is 4.2% of the total amount of the mixture.

[0061] Example 2

[0062] The raw material composition of the refractory castable for the tapping trough of the small blast furnace in this embodiment is shown in Table 1. The difference from that in Embodiment 1 is that the raw material composition ratio is different.

[0063] Example 3

[0064] The raw material composition of the refractory castable for the tapping trough of the small blast furnace in this embodiment is shown in Table 1. The difference from that in Embodiment 1 is that the raw material composition ratio is different.

[0065] Comparative Example

[0066] Comparative Example 1

[0067] The difference between the refractory castable for the tapping trough of the small blast furnace in this comparative example and Example 1 is that the castable used is Al2O3-SiC-C, which is commercially available and manufactured by Yuqiu Refractory Materials Co., Ltd.

[0068] Comparative Example 2

[0069] The difference between the refractory castable for the tapping trough of the small blast furnace in this comparative example and Example 1 is that nano-rare earth oxides were not added.

[0070] Comparative Example 3

[0071] The refractory castable for the tapping trough of the small blast furnace in this comparative example differs from that in Example 1 in that high-alumina brown corundum powder is used to replace nano-rare earth oxides in an equal amount. The high-alumina brown corundum powder is subjected to magnetic separation to remove iron.

[0072] Comparative Example 4

[0073] The refractory castable for the tapping trough of the small blast furnace in this comparative example differs from that in Example 1 in that polyvinyl alcohol ultra-short fibers are used to replace alumina fibers in equal amounts. The polyvinyl alcohol ultra-short fibers have a length of 5 mm and a diameter of 3-7 μm.

[0074] Comparative Example 5

[0075] The refractory castable for the tapping trough of the small blast furnace in this comparative example differs from that in Example 1 in that it includes the following raw materials by weight: 35 kg of bauxite, 15 kg of brown corundum, 20 kg of nano-rare earth oxides, 4 kg of activated alumina, 10 kg of silicon carbide, 2 kg of metallic silicon, 5 kg of dispersant, 5 kg of antioxidant, 5 kg of carbon nanotube fiber, and 5 kg of alumina fiber.

[0076] Performance testing

[0077] Slag erosion resistance test: The refractory castables of the tapping trough of the small blast furnace in Examples 1-3 and Comparative Examples 1-5 were tested for slag resistance according to the test methods in GB / T8931-2007 "Test Method for Slag Resistance of Refractory Materials". The test results are shown in Table 2.

[0078] Compressive strength test: The refractory castables of the tapping trough of the small blast furnace in Examples 1-3 and Comparative Examples 1-5 were tested according to the test method in GB / T5072-2008 "Test method for compressive strength of refractory materials at room temperature". The test results are shown in Table 2.

[0079] Flexural strength test: The refractory castables of the tapping trough of the small blast furnace in Examples 1-3 and Comparative Examples 1-5 were used to test the flexural strength of the refractory castables according to the test method in GB / T3001-2017 "Test method for flexural strength of refractories at room temperature". The test results are shown in Table 2.

[0080] Permanent linear change test: Refractory castables from the tapping troughs of small blast furnaces in Examples 1-3 and Comparative Examples 1-5 were used. The permanent linear change rate of the refractory castables was tested according to the test method in GB / T5988-2007 "Test Method for Permanent Linear Change of Refractory Materials under Heating". The test results are shown in Table 2.

[0081] Explosion-proof temperature test: The refractory castables from the tapping troughs of small blast furnaces in Examples 1-3 and Comparative Examples 1-5 were tested according to the test method in YB / T4117-2003 "Test Method for Explosion Resistance of Dense Refractory Castables". The test results are shown in Table 2.

[0082] Table 2. Performance test results of refractory castables for tapping troughs of small blast furnaces in Examples 1-3 and Comparative Examples 1-5.

[0083]

[0084]

[0085] Based on Examples 1-3 and the data in Table 2, it can be seen that by using the raw materials and proportions described in Examples 1-3, and by combining the raw materials with each other, the resulting refractory castable has a lower average erosion depth, higher compressive strength and flexural strength, a smaller permanent linear change rate, and a higher explosion-proof temperature.

[0086] Combining Example 1 and Comparative Example 1, and referring to the data in Table 2, it can be seen that the refractory castable prepared in Example 1 has better performance than the commercially available Al2O3-SiC-C used in Comparative Example 1. By using the raw materials and proportions of this application, and by introducing bauxite, brown corundum, nano-rare earth oxides, activated alumina, silicon carbide, metallic silicon, dispersant, antioxidant, carbon nanotube fiber, and alumina fiber, the refractory castable for blast furnace tapping troughs exhibits high compressive strength and flexural strength, and a small permanent linear change rate upon heating. Therefore, the product has a long service life, low melting rate, strong oxidation resistance, and high thermal shock stability. Furthermore, nano-rare earth oxides can improve the crystallization state of the main crystalline phase in the tapping trough refractory castable, reduce defects, and thus increase its chemical stability, resulting in stronger oxidation resistance and better performance.

[0087] Based on Example 1 and Comparative Example 2, and the data in Table 2, it can be seen that the refractory castable prepared in Example 1 has better performance. The difference between Example 1 and Comparative Example 2 is that nano-rare earth oxides are added in Example 1. The nano-rare earth oxides work together with other components in the castable to help improve the mechanical properties of the refractory castable and have better resistance to slag erosion.

[0088] Based on Example 1 and Comparative Example 3, and the data in Table 2, it can be seen that the refractory castable prepared in Example 1 has better performance. The difference between Example 1 and Comparative Example 3 is that Comparative Example 3 uses high-alumina brown corundum powder to replace nano-rare earth oxides in equal amounts. The refractory castable prepared in this way has poor slag erosion resistance and poor mechanical properties.

[0089] Based on Example 1 and Comparative Example 4, and the data in Table 2, it can be seen that the refractory castable prepared in Example 1 has better performance. The difference between Example 1 and Comparative Example 4 is that Comparative Example 4 uses an equal amount of polyvinyl alcohol short fibers to replace alumina fibers, resulting in a refractory castable with poor overall performance. The addition of alumina fibers has a significant impact on the overall performance of the refractory castable.

[0090] Combining Example 1 and Comparative Example 5, and referring to the data in Table 2, it can be seen that the refractory castable prepared in Example 1 has better performance. The difference between Example 1 and Comparative Example 5 is that Comparative Example 5 added too much nano-rare earth oxide, resulting in a lower average erosion depth of the refractory castable, but relatively poor flexural strength and compressive strength.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A refractory castable for the tapping trough of a small blast furnace, characterized in that: The refractory castable comprises the following raw materials in parts by weight: 40-50 parts of bauxite, 10-20 parts of brown corundum, 10-15 parts of nano-rare earth oxides, 5-10 parts of activated alumina, 5-10 parts of silicon carbide, 2-3 parts of metallic silicon, 3-5 parts of dispersant, 3-5 parts of antioxidant, 3-5 parts of carbon nanotube fiber, and 3-5 parts of alumina fiber; the nano-rare earth oxides are composed of nano-cerium dioxide and nano-lanthanum oxide in a mass ratio of (5-7):(3-5).

2. The refractory castable for the tapping trough of a small blast furnace according to claim 1, characterized in that: It also includes one or more of the following features: 1) The dispersant is at least one of sodium hexametaphosphate and sodium tripolyphosphate; 2) The antioxidant is at least one of metallic silicon powder and boron carbide; 3) The brown fused alumina is electrofused brown fused alumina; 4) The silicon carbide is at least one of silicon carbide particles and silicon carbide fine powder; 5) The diameter of the carbon nanotube fiber is 2-20 nm, and the length of the single filament is 10-150 mm; 6) The diameter of the alumina fiber is 2-20 μm, and the length of the single filament is 10-150 mm; 7) The particle size of the activated alumina is less than 2 μm.

3. The refractory castable for the tapping trough of a small blast furnace according to claim 2, characterized in that: It also includes one or more of the following features: 11) The dispersant is composed of sodium hexametaphosphate and sodium tripolyphosphate; 21) The antioxidant is composed of metallic silicon powder and boron carbide; 31) The fused brown fused alumina is at least one of fused brown fused alumina particles and fused brown fused alumina fine powder; 32) The fused brown corundum contains ≥95 wt% Al2O3 and ≤0.5 wt% Fe2O3. 41) The silicon carbide is composed of silicon carbide particles and silicon carbide fine powder.

4. The refractory castable for the tapping trough of a small blast furnace according to claim 3, characterized in that: It also includes one or more of the following features: 111) The dispersant is composed of sodium hexametaphosphate and sodium tripolyphosphate in a mass ratio of (1-2):(2-5); 211) The antioxidant is composed of metallic silicon powder and boron carbide in a mass ratio of (3-5):(1-3); 311) The fused brown fused alumina is composed of fused brown fused alumina particles and fused brown fused alumina fine powder; 312) The particle size of the electrofused brown corundum fine powder is 180-200 mesh; 411) The silicon carbide is composed of silicon carbide particles and silicon carbide fine powder in a mass ratio of (1-3):(3-9); 412) The particle size of the silicon carbide fine powder is 300-325 mesh.

5. The refractory castable for the tapping trough of a small blast furnace according to claim 4, characterized in that: In 311), the fused brown fused alumina is composed of fused brown fused alumina particles and fused brown fused alumina fine powder in a mass ratio of (2-4):(1-2).

6. The refractory castable for the tapping trough of a small blast furnace according to claim 1, characterized in that: The average erosion depth of the refractory castable in the slag resistance test is ≤5mm; the compressive strength of the refractory castable is >54MPa; the flexural strength of the refractory castable is ≥12MPa; and the permanent linear change rate of the refractory castable is ≤0.

5.

7. The refractory castable for the tapping trough of a small blast furnace according to claim 6, characterized in that: The average erosion depth of the refractory castable in the slag resistance test is 3-5 mm; the compressive strength of the refractory castable is 54.3-55.7 MPa; the flexural strength of the refractory castable is 12-14 MPa; and the permanent linear change rate of the refractory castable is 0.3-0.

5.

8. The refractory castable for the tapping trough of a small blast furnace according to claim 1, characterized in that: It also includes one or more of the following features: (I) The Al2O3 content in the bauxite is ≥88%; (II) The alumina has a particle size of at least one of 1-3 mm, 3-5 mm or 5-8 mm.

9. The refractory castable for the tapping trough of a small blast furnace according to claim 8, characterized in that: The particle size distribution of the bauxite is 1-3mm 30-50wt%, 3-5mm 20-30wt%, and 5-8mm 25-30wt%.

10. A method for preparing a refractory castable for the tapping trough of a small blast furnace as described in any one of claims 1-9, characterized in that: Includes the following steps: (1) Mix and stir bauxite, brown corundum, nano rare earth oxides, activated alumina, silicon carbide, metallic silicon, dispersant, antioxidant, carbon nanotube fiber and alumina fiber to obtain a mixture; (2) Add water to the mixture obtained in step (1), mix to obtain slurry, pour the slurry into the mold, pour and vibrate to form, demold, dry, keep warm and cool to obtain the final product.

11. The method for preparing the refractory castable for the tapping trough of a small blast furnace according to claim 10, characterized in that: In step (2), the weight of water is 4.0-4.2% of the total amount of the mixture; and / or, the method of adding water is to first add 80-85% water, stir evenly, then add 15-20% water, and stir again; and / or, the mixing time in step (2) is 180-300s.

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