Preparation method and special equipment for a high-strength and wear-resistant trough material

Abstract

The present invention discloses a preparation method and a special equipment for a high-strength wear-resistant trough material, belonging to the technical field of trough material production. By using the mixer of the present invention, dry and wet raw materials are added into the dry and wet premixing chambers, stirred for 1 to 2 hours. After the premixing is completed, the dry and wet raw materials enter the mixing chamber and continue to be stirred. After being uniform, they are cast and formed; the formed green body is dried at 110°C for 10 to 24 hours, fired under the condition of 1450 to 1550°C, and heat-insulated for 1 to 6 hours to obtain the trough material; the raw materials are composed of the following components in parts by weight: 56 to 64 parts of bauxite aggregate, 19 to 33 parts of silicon carbide, 4 to 10 parts of α-aluminum oxide micropowder, 2 to 6 parts of pyrophyllite and 2 to 4 parts of calcium aluminate cement; the additive is composed of 0.6 to 1.2 parts of silica fume, 0.5 to 2.5 parts of spherical asphalt and 0.06 to 0.16 parts of water reducer. The process of the present invention is simple and the cost is low, and the prepared high-strength wear-resistant trough material has high strength and good wear resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of trough material production, and particularly relates to a preparation method and special equipment for a high-strength wear-resistant trough material. Background Art

[0002] The blast furnace trough serves as a transportation channel to convey molten iron and slag to a container. During this process, the refractory material used in the trough is periodically eroded and worn by molten iron and slag and undergoes repeated thermal cycling for a long time, causing the material to crack and damage easily, thus seriously affecting the quality and performance of molten iron. The main reason for this phenomenon is that the refractory material used in the trough has low strength, poor wear resistance and erosion resistance.

[0003] At the same time, with the rapid development of steel production, blast furnaces are gradually transformed into large-scale ones, showing characteristics such as high molten iron flow rate, large tapping volume, and high molten iron temperature, which further accelerate the damage rate of the refractory material used in the trough. Therefore, improving the performance of trough materials has become an urgent problem to be solved.

[0004] An Al 2 O 3 -SiC-C refractory castable for trough and its preparation method (CN103011868A) discloses a method using fused brown corundum particles, silicon carbide particles, silicon carbide fine powder, α-Al 2 O 3 micropowder, silica micropowder, metal antioxidant, dispersant and calcium aluminate cement as raw materials, and adding a metal catalyst externally, and dry mixing evenly to obtain Al 2 O 3-SiC-C refractory castable for the runner. This method improves the high-temperature strength and thermal shock stability of the runner material to a certain extent. However, its main defects are: (1) The pores in the runner material are not well filled, resulting in a significant reduction in wear resistance and erosion resistance. (2) The variety of raw materials leads to an increase in production costs. A recycled runner material (CN105218119A) discloses a low-cost runner castable prepared mainly from corundum, bauxite, and skate grinding waste of carbonaceous materials. This method saves resources and reduces environmental pollution to a certain extent. However, its main defects are: (1) The high impurity content in the skate grinding waste seriously affects the performance of the runner material; (2) The low densification degree is not conducive to the wear resistance and molten iron erosion resistance of the runner material. The application research of Sialon-TiNC composite materials in the refractory materials for the blast furnace runner (Steelmaking, 2011, 30(6)) discloses the preparation of Sialon-TiNC composite materials using pyrophyllite, rutile, and coke to replace corundum and silicon carbide for the refractory materials of the blast furnace runner. This method improves the erosion resistance of the refractory materials to a certain extent and has a relatively low cost. However, its main defects are: (1) Its process is extremely complex: titanium dioxide and pyrophyllite are proportioned and coke is added externally, and the powder is prepared through processes such as wet ball milling for 6 hours, drying, and grinding. Then the powder is pressed into a round blank and prepared into Sialon-TiNC powder through drying and nitriding firing. (2) The mechanical strength and erosion resistance of the prepared Sialon-TiNC composite are significantly different from those of corundum and silicon carbide. (3) The wear resistance of the material is not improved by using the liquid phase and mullite fibers generated by the in-situ decomposition reaction of pyrophyllite. A ladle lip anti-adhesion slag castable containing pyrophyllite (CN103601511A) discloses a ladle lip anti-adhesion slag castable prepared from 50-70% bauxite clinker aggregate, 5-15% pyrophyllite aggregate, 5-15% pyrophyllite fine powder, 7-11% bauxite clinker powder, 4-8% ordinary silica fume, and 5-8% high-alumina cement. This method improves the densification of the material and the anti-adhesion slag property of the ladle lip to a certain extent through the in-situ decomposition mechanism of pyrophyllite. However, its main defects are: (1) The excessive addition of pyrophyllite leads to the generation of a large amount of molten liquid phase at high temperature, significantly reducing the high-temperature strength and stability of the material. (2) The molten liquid phase reacts with bauxite to generate a large amount of secondary mullite, resulting in volume expansion and cracking of the matrix. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the technical problems to be solved by the present invention are to provide a high-strength wear-resistant trough material, which has good wear resistance and excellent thermal shock stability. Another technical problem to be solved by the present invention is to provide a preparation method of a high-strength wear-resistant trough material. This preparation method first premixes dry and wet raw materials separately and then mixes them, making the raw material mixing more sufficient and more efficient. Another technical problem to be solved by the present invention is to provide a mixer for preparing a high-strength wear-resistant trough material. This mixer is provided with a premixing chamber for raw materials, separates the premixing of dry and wet materials, and then mixes dry and wet materials evenly, which can achieve sufficient mixing of materials and improve the mixing degree of materials.

[0006] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0007] A preparation method of a high-strength wear-resistant trough material. First, add dry and wet raw materials into the dry premixing chamber and the wet premixing chamber respectively, stir for 1 - 2 h. After the premixing is completed, remove the baffle, and the dry and wet raw materials enter the mixing chamber, continue to stir, and after mixing evenly, cast and form. Then dry the formed green body at 110 °C for 10 - 24 h, and then sinter at 1450 - 1550 °C, keep warm for 1 - 6 h, and then a high-strength wear-resistant trough material is obtained. The raw materials are composed of the following components in parts by weight: 56 - 64 parts of bauxite aggregate, 19 - 33 parts of silicon carbide, 4 - 10 parts of α-aluminum oxide micropowder, 2 - 6 parts of pyrophyllite, and 2 - 4 parts of calcium aluminate cement. The additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer.

[0008] For the preparation method of the high-strength wear-resistant trough material, the raw materials are composed of the following components in parts by weight: additive, 56 - 59 parts of bauxite aggregate, 27 - 33 parts of silicon carbide, 4 - 6 parts of α-aluminum oxide micropowder, 2 - 3 parts of pyrophyllite, and 3 - 4 parts of calcium aluminate cement. The additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer.

[0009] For the preparation method of the high-strength wear-resistant trough material, the raw materials are composed of the following components in parts by weight: additive, 59 - 62 parts of bauxite aggregate, 22 - 27 parts of silicon carbide, 6 - 8 parts of α-aluminum oxide micropowder, 3 - 5 parts of pyrophyllite, and 2.5 - 3 parts of calcium aluminate cement. The additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer.

[0010] The preparation method of the high-strength wear-resistant trough material, wherein the raw materials are composed of the following components in parts by weight: additive, 62-64 parts of bauxite aggregate, 9-22 parts of silicon carbide, 8-10 parts of α-aluminum oxide micropowder, 5-6 parts of pyrophyllite and 2-2.5 parts of calcium aluminate cement; the additive is composed of 0.6-1.2 parts of silica fume, 0.5-2.5 parts of spherical asphalt and 0.06-0.16 parts of water reducer.

[0011] The preparation method of the high-strength wear-resistant trough material, wherein in the bauxite aggregate, Al 2 O 3 ≥87wt.%; the gradation of the bauxite aggregate is: the particle size of 5-8mm accounts for 30%-35% of the bauxite aggregate, the particle size of 3-5mm accounts for 27%-33% of the bauxite aggregate, and the particle size of 1-3mm accounts for 35%-40% of the bauxite aggregate.

[0012] The preparation method of the high-strength wear-resistant trough material, wherein in the silicon carbide, SiC≥97wt.%; the particle size distribution of the silicon carbide is: the particle size of 0-1mm accounts for 42%-57% of the silicon carbide, the particle size of 0.075mm accounts for 22%-35% of the silicon carbide, and the particle size of 0.044mm accounts for 20%-24% of the silicon carbide.

[0013] The preparation method of the high-strength wear-resistant trough material, wherein in the chemical composition of the pyrophyllite, SiO 2 accounts for 60-70wt.%, Al 2 O 3 accounts for 23-30wt.%, Fe 2 O 3 accounts for 1-3wt.%, CaO+MgO accounts for 0.5-1.0wt.%, and the loss on ignition is 3-5wt.%; the particle size of the pyrophyllite≤0.5mm.

[0014] The preparation method of the high-strength wear-resistant trough material, wherein the particle size of the α-aluminum oxide micropowder≤0.005mm; the particle size of the silica fume≤0.045mm; the particle size of the spherical asphalt≤0.1mm.

[0015] The high-strength wear-resistant trough material prepared by the above preparation method of the high-strength wear-resistant trough material.

[0016] A mixer for preparing high-strength and wear-resistant iron runner materials, comprising a dry material premixing chamber, a wet material premixing chamber and a mixing chamber. The dry material premixing chamber and the wet material premixing chamber are arranged above the mixing chamber. Feed inlets are arranged at the upper parts of the dry material premixing chamber and the wet material premixing chamber. The mixing chamber is of a conical structure with a large upper opening and a small lower opening. A discharge port and a support are arranged at the bottom of the mixing chamber. A first stirring device is arranged in the mixing chamber, and second stirring devices with the same structure are arranged in the dry material premixing chamber and the wet material premixing chamber. The first stirring device includes a first servo motor, a first support rod and a first stirring paddle. The first servo motor is connected to the first support rod. The first support rod is arranged in the mixing chamber, and the first stirring paddle is arranged on the first support rod. The second stirring device includes a second support rod, a second servo motor, a second stirring paddle, a first cross bar, a first reamer and a second reamer. The second support rod is arranged in the dry material premixing chamber and the wet material premixing chamber. The second servo motor is connected to the second support rod, and the second stirring paddle is arranged on the second support rod. The first cross bar is arranged on the second support. The first reamer is fixedly arranged on the first cross bar through a connecting rod, and the second reamer is arranged at the bottom of the second support rod. A baffle is arranged between the premixing chamber and the mixing chamber. The baffle is arranged on the first support rod through a baffle fixing structure. The baffle fixing structure is a groove arranged at the upper part of the first support rod, and the baffle is arranged in the groove. A handle is arranged at the end of the baffle.

[0017] Beneficial effects: Compared with the existing technology, the advantages of the present invention include:

[0018] (1) The present invention uses pyrophyllite as an additive and adds it to the iron runner material. The mullite whiskers and fused quartz phase generated by its decomposition under high-temperature conditions can effectively fill the internal pores of the iron runner material, improving the strength and wear resistance of the material. In addition, the in-situ generated mullite whiskers have characteristics such as erosion resistance, high modulus, high temperature resistance and oxidation resistance, which have a good effect on inhibiting the diffusion of cracks in the matrix. In addition, due to the interface debonding effect and fiber pull-out effect generated by the mullite fibers in the matrix, etc., the iron runner material is toughened and reinforced.

[0019] (2) The volume density of the high-strength and wear-resistant iron runner material product prepared by the present invention is 3.00 - 3.10 g / cm 3 after drying, the flexural strength at room temperature is 15 - 18 MPa. After heat treatment at 1400 °C, the volume density of the sample is 2.95 - 3.07 g / cm 3 , and the flexural strength is 20 - 25 MPa. The retention rate of the flexural strength after five thermal shock experiments (water cooling) is as high as 67%.

[0020] (3) The present invention has the characteristics of low cost and simple process. The prepared high-strength and wear-resistant iron runner material has the advantages of high strength and good wear resistance.

[0021] (4) The mixer of the present invention is provided with a premixing chamber for materials, and the premixing of dry and wet materials is carried out separately, and then the dry and wet materials are mixed evenly, which can achieve the full mixing of the materials and improve the mixing degree of the materials. In addition to the mixing paddle in the second stirring device, which can improve the stirring effect, the first reamer and the second reamer are also provided. The structure of the reamer can clean the materials adhering to the inner wall of the premixing chamber in time, further improving the stirring effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of a mixer for preparing high-strength wear-resistant iron runner material;

[0023] Figure 2 For Figure 1 an enlarged view of structure A in;

[0024] Figure 3 It is a schematic structural diagram of the second stirring device. DETAILED DESCRIPTION OF THE INVENTION

[0025] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to specific embodiments.

[0026] The specifications of the raw materials used in the present invention are as follows: The main chemical component of bauxite aggregate is: Al 2 O 3 ≥87 wt.%; The gradation of bauxite aggregate is: The particle size of 5 - 8 mm accounts for 30% - 35% of bauxite aggregate, the particle size of 3 - 5 mm accounts for 27% - 33% of bauxite aggregate, and the particle size of 1 - 3 mm accounts for 35% - 40% of bauxite aggregate.

[0027] The main chemical component of silicon carbide is: SiC≥97 wt.%; The gradation of silicon carbide particles is: The particle size of 0 - 1 mm accounts for 42% - 57% of silicon carbide, the particle size of 0.075 mm accounts for 22% - 35% of silicon carbide, and the particle size of 0.044 mm accounts for 20% - 24% of silicon carbide.

[0028] The particle size of α-aluminum oxide micropowder ≤0.005 mm.

[0029] The main chemical component of pyrophyllite is: SiO 2 is 60 - 70 wt.%, Al 2 O 3 is 23 - 30 wt.%, Fe 2 O 3 is 1 - 3 wt.%, CaO + MgO is 0.5 - 1.0 wt.%, and the loss on ignition is 3 - 5 wt.%; The particle size of pyrophyllite ≤0.5 mm.

[0030] The particle size of silica fume ≤0.045 mm, and the particle size of spherical asphalt ≤0.1 mm.

[0031] A mixer for preparing high-strength and wear-resistant trough material, comprising a dry material premixing chamber 1, a wet material premixing chamber 2 and a mixing chamber 3. The dry material premixing chamber 1 and the wet material premixing chamber 2 are arranged above the mixing chamber 3; the upper parts of the dry material premixing chamber 1 and the wet material premixing chamber 2 are provided with feed inlets; baffles 9 are arranged between the dry material premixing chamber 1 and the mixing chamber 3, and between the wet material premixing chamber 2 and the mixing chamber 3. The baffle 9 is arranged on the first support rod 7 through a baffle fixing structure A. The baffle fixing structure A is a groove arranged at the upper part of the first support rod 7. The baffle 9 is arranged in the groove, and a handle 10 is arranged at the end of the baffle 9; when the premixing chamber works, the baffle 9 is clamped in the groove of the first support rod 1 to fix the baffle 9 at the lower part of the premixing chamber. After the premixing chamber finishes working, the staff holds the handle and pulls out the baffle 9, and the dry and wet materials in the premixing chamber enter the mixing chamber. The structure is simple, the operation is convenient, and the equipment cost is saved.

[0032] The mixing chamber 3 is of a conical structure with a large upper opening and a small lower opening. A discharge port 5 and a support 4 are arranged at the bottom of the mixing chamber 3. A first stirring device is arranged in the mixing chamber 3. The first stirring device includes a first servo motor 6, a first support rod 7 and a first stirring paddle 8. The first servo motor 6 is connected to the first support rod 7. The first support rod 7 is arranged in the mixing chamber 3, and a first stirring paddle 8 is arranged on the first support rod 7; the conical structure of the mixing chamber 3 can effectively improve the mixing degree of dry and wet materials and improve the efficiency.

[0033] Second stirring devices with the same structure are arranged in the dry material premixing chamber 1 and the wet material premixing chamber 2; the second stirring device includes a second support rod 11, a second servo motor 12, a second stirring paddle 13, a first cross bar, a first reamer 14 and a second reamer 15. The second support rod 11 is arranged in the dry material premixing chamber 1 and the wet material premixing chamber 2. The second servo motor 12 is connected to the second support rod 11, and a second stirring paddle 13 is arranged on the second support rod 11; the first cross bar is arranged on the second support rod 11, and the first reamer is arranged on the first cross bar through a connecting rod; the second reamer is arranged at the bottom of the second support rod 11. In addition to the stirring paddle, the first reamer and the second reamer in the second stirring device of the mixer can improve the stirring effect. The structure of the reamer can clean the materials adhering to the inner wall of the premixing chamber in time, further improving the stirring effect. The function of setting the premixing chamber is to separate the premixing of dry and wet materials and then carry out the dry-wet mixing, which can realize the full mixing of materials and improve the mixing degree of materials.

[0034] Example 1

[0035] A preparation method of a high-strength wear-resistant trough material. Using the above-mentioned mixer for preparing the high-strength wear-resistant trough material, first separately load the dry and wet materials into the dry pre-mixing chamber and the wet pre-mixing chamber, stir and mix evenly for 1.5 h. After the pre-mixing is completed, remove the baffle, and the dry and wet materials enter the mixing chamber, continue to stir evenly, and then cast and form. Then dry the formed blank at 110 °C for 18 h, and then sinter at 1550 °C and keep warm for 2 h to obtain the high-strength wear-resistant trough material. The above raw materials are composed of the following components in parts by weight: additive, 56 - 59 parts; bauxite aggregate, 27 - 33 parts; silicon carbide, 4 - 6 parts; α-aluminum oxide fine powder, 2 - 3 parts; pyrophyllite, 3 - 4 parts; and calcium aluminate cement, 3 - 4 parts. The additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer.

[0036] The volume density of the high-strength wear-resistant trough material product prepared in Example 1 after drying is 3.00 - 3.03 g / cm 3 , the flexural strength at room temperature is 15 - 16 MPa. After heat treatment at 1400 °C, the volume density of the specimen is 2.95 - 3.01 g / cm 3 , and the flexural strength is 20 - 22 MPa. The retention rate of the flexural strength after five thermal shock tests (water cooling) is as high as 67%.

[0037] Example 2

[0038] A preparation method of a high-strength wear-resistant trough. Using the above-mentioned mixer for preparing the high-strength wear-resistant trough material, first separately load the dry and wet materials into the dry pre-mixing chamber and the wet pre-mixing chamber, stir and mix evenly for 2 h. After the pre-mixing is completed, remove the baffle, and the dry and wet materials enter the mixing chamber, continue to stir evenly, and then cast and form. Then dry the formed blank at 110 °C for 22 h, and then sinter at 1450 °C and keep warm for 4 h to obtain the high-strength wear-resistant trough material. The above raw materials are composed of the following components in parts by weight: additive, 59 - 62 parts; bauxite aggregate, 22 - 27 parts; silicon carbide, 6 - 8 parts; α-aluminum oxide fine powder, 3 - 5 parts; pyrophyllite, 3 - 5 parts; and calcium aluminate cement, 2.5 - 3 parts. The additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer.

[0039] The volume density of the high-strength wear-resistant trough material product prepared in Example 2 after drying is 3.03 - 3.07 g / cm 3 , the flexural strength at room temperature is 16 - 17 MPa. After heat treatment at 1400 °C, the volume density of the specimen is 3.01 - 3.03 g / cm 3 , and the flexural strength is 22 - 24 MPa. The retention rate of the flexural strength after five thermal shock tests (water cooling) is as high as 67%.

[0040] Example 3

[0041] A preparation method of a high-strength and wear-resistant iron runner. Using the above-mentioned mixer for preparing high-strength and wear-resistant iron runner materials, first load dry and wet materials into the intervention mixing chamber and the wet premixing chamber respectively, stir and mix evenly for 1 h. After the premixing is completed, remove the baffle, and the dry and wet materials enter the mixing chamber, continue to stir evenly, and then cast and form. Then dry the formed green body at 110 °C for 12 h, and then sinter at 1550 °C for 6 h to obtain the high-strength and wear-resistant iron runner material. The above raw materials are composed of the following components in parts by weight: 62 - 64 parts of additive, 19 - 22 parts of bauxite aggregate, 8 - 10 parts of silicon carbide, 5 - 6 parts of pyrophyllite, and 2 - 2.5 parts of calcium aluminate cement; the additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer.

[0042] The volume density of the high-strength and wear-resistant iron runner material product prepared in Example 3 after drying is 3.07 - 3.10 g / cm 3 , the room temperature flexural strength is 17 - 18 MPa. After heat treatment at 1400 °C, the volume density of the specimen is 3.03 - 3.07 g / cm 3 , the flexural strength is 24 - 25 MPa, and the retention rate of the flexural strength after five thermal shock experiments (water cooling) is as high as 67%.

[0043] From the above experimental results, it can be seen that in the present invention, pyrophyllite is used as an additive and added to the iron runner material. The mullite whiskers and fused quartz phase generated by its decomposition under high-temperature conditions can effectively fill the internal pores of the iron runner material, promote the densification of the material, and further improve the strength and wear resistance of the material. In addition, the in-situ generated mullite whiskers have properties such as erosion resistance, high modulus, high temperature resistance, and oxidation resistance, and have a good effect on inhibiting the propagation of cracks in the matrix. In addition, due to the interface debonding effect and fiber pull-out effect generated by the mullite fibers in the matrix, the flexural strength of the iron runner material is significantly improved. Therefore, using pyrophyllite as an additive and adding it to the iron runner material plays a role in toughening and strengthening the iron runner material.

[0044] The volume density of the high-strength and wear-resistant iron runner material product prepared by the present invention after drying is 3.00 - 3.10 g / cm 3 , the room temperature flexural strength is 15 - 18 MPa. After heat treatment at 1400 °C, the volume density of the specimen is 2.95 - 3.07 g / cm 3 , the flexural strength is 20 - 25 MPa, and the retention rate of the flexural strength after five thermal shock experiments (water cooling) is as high as 67%.

[0045] Therefore, the present invention has the characteristics of low cost and simple process, and the prepared high-strength and wear-resistant iron runner material has the advantages of high strength and good wear resistance.

[0046] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Any person skilled in the relevant art, without departing from the scope of the technical solution of the present invention and based on the technical essence of the present invention, any simple modification, equivalent replacement, improvement, etc. made to the above embodiments shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A high-strength wear-resistant trough material, characterized in that, during preparation, dry and wet raw materials are respectively added into the dry premixing chamber and the wet premixing chamber, stirred for 1 h, the baffle is removed after the premixing is completed, the dry and wet raw materials enter the mixing chamber, continue to be stirred, and are cast into shape after being mixed evenly; then the formed green body is dried at 110 °C for 12 h, and then fired at 1550 °C, with heat preservation for 6 h, thus obtaining the high-strength wear-resistant trough material; the raw materials are composed of the following components in parts by weight: 62 - 64 parts of additive, 19 - 22 parts of bauxite aggregate, 8 - 10 parts of silicon carbide, 5 - 6 parts of pyrophyllite, and 2 - 2.5 parts of calcium aluminate cement; the additive is composed of 0.6 - 1.2 parts of silica fume, 0.5 - 2.5 parts of spherical asphalt, and 0.06 - 0.16 parts of water reducer; The Al in the bauxite aggregate 2 O 3 ≥ 87 wt.%; The grading of the bauxite aggregate is as follows: the particle size of 5 - 8 mm accounts for 30% - 35% of the bauxite aggregate, the particle size of 3 - 5 mm accounts for 27% - 33% of the bauxite aggregate, and the particle size of 1 - 3 mm accounts for 35% - 40% of the bauxite aggregate; SiC ≥ 97 wt.% in the silicon carbide; the particle size distribution of the silicon carbide is: 42% - 57% of the silicon carbide has a particle size of 0 - 1 mm, 22% - 35% of the silicon carbide has a particle size of 0.075 mm, and 20% - 24% of the silicon carbide has a particle size of 0.044 mm; The pyrophyllite contains SiO 2 accounting for 60 - 70 wt.%, Al 2 O 3 accounting for 23 - 30 wt.%, Fe 2 O 3 accounting for 1 - 3 wt.%, CaO + MgO accounting for 0.5 - 1.0 wt.%, and the loss on ignition is 3 - 5 wt.%; the particle size of the pyrophyllite is ≤ 0.5 mm; the particle size of the α-aluminum oxide micropowder ≤ 0.005 mm; the particle size of the silica fume ≤ 0.045 mm; the particle size of the spherical asphalt ≤ 0.1 mm.

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