Aluminum silicon carbide carbon brick for deep desulfurization of a ladle and a preparation method thereof

Abstract

This invention discloses an aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles and its preparation method. The aluminum silicon carbide carbon brick is composed of aluminum silicon carbide raw materials, flake graphite, a composite antioxidant, and a binder; or it is composed of aluminum silicon carbide raw materials, flake graphite, a composite antioxidant, a binder, and rare earth oxides. The aluminum silicon carbide raw material is a single recycled corundum silicon carbide composite material; or the aluminum silicon carbide raw material is a mixture of recycled corundum silicon carbide composite material and erosion-resistant raw materials. The preparation method is as follows: dry materials with a particle size greater than 100 mesh are mixed to obtain mixed dry material A; dry materials with a particle size less than or equal to 100 mesh (excluding flake graphite) are mixed to obtain mixed dry material B; a binder, flake graphite, and mixed dry material B are sequentially added to mixed dry material A and mixed to obtain a mixture; the mixture is pressed into a green body; and the green body is dried and baked. This invention can solve the technical problems of high raw material prices and poor thermal shock stability of aluminum silicon carbide carbon bricks for deep desulfurization.

Description

Technical Field

[0001] This invention relates to the field of aluminum silicon carbide carbon brick technology. Specifically, it relates to an aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles and its preparation method. Background Technology

[0002] Currently, the raw materials used in aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles are mainly high-grade fused alumina, such as brown fused alumina, fused white fused alumina, or high-purity alumina (such as sheet alumina), as well as other high-purity, erosion-resistant raw materials with good thermal shock resistance, such as high-purity silicon carbide. This results in excessively high raw material formulation costs for existing aluminum silicon carbide carbon bricks used in high-grade deep desulfurization of molten iron ladles (desulfurization percentage greater than 50%). To reduce raw material costs and conserve high-quality, high-temperature material resources, it is necessary to find lower-cost raw materials to replace sheet high-grade fused alumina or silicon carbide.

[0003] Patent document CN111253166A discloses an Al2O3-SiC-C brick containing recycled materials and its preparation method. This method utilizes recycled granules with corundum, high-alumina bauxite, silicon carbide, and graphite to prepare Al2O3-SiC-C bricks. The recycled granules contain: Al2O3 ≥ 80.0%, SiC ≤ 3.0%, C ≤ 3.0%, SiO2 ≤ 10.0%, and K2O + Na2O ≤ 0.5%. The resulting Al2O3-SiC-C brick exhibits good resistance to slag erosion and molten iron scouring, high high-temperature flexural strength, and excellent thermal shock resistance.

[0004] Patent document CN105110790 A discloses a zirconia refractory material and its preparation method. The zirconia refractory material is composed of the following raw materials by weight percentage: 75-80% zirconia raw material, 2.6-3% nano-alumina, 5-6.4% graphene, 1-2% additives, 1-3% titanium dioxide, 1-3% silicon carbide, 1.5-3% boron carbide, 2-5% nano-magnesium oxide, and 1-4% nano-neodymium oxide. The above raw materials are mixed evenly, sintered at high temperature using a plasma arc, held at that temperature, and then cooled to obtain the zirconia refractory material. This patented product is a ceramic material product, specifically a high-temperature ceramic-bonded refractory material, and is not suitable for bricks used in deep desulfurization of molten iron ladles.

[0005] However, the iron ladle bricks prepared using recycled granules cannot meet the application requirements of bricks for deep desulfurization of iron ladles. Therefore, it is necessary to find new low-cost aluminum silicon carbide carbon bricks for deep desulfurization of iron ladles with excellent thermal shock resistance and their preparation methods. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide an aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle and its preparation method, so as to solve the technical problems of high raw material price and poor thermal shock stability of existing high-grade deep desulfurization (desulfurization percentage greater than 50%) aluminum silicon carbide carbon bricks.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] An aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles is composed of aluminum silicon carbide raw materials, flake graphite, composite antioxidants, and binders; or it is composed of aluminum silicon carbide raw materials, flake graphite, composite antioxidants, binders, and rare earth oxides. The flake graphite, together with other components of this invention, is used to prepare the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles, which can effectively reduce the oxidation degree of the aluminum silicon carbide carbon brick, improve the thermal shock resistance of the brick, and also improve its mechanical properties.

[0009] The aluminum-carbon-silicon raw material is a single recycled corundum-silicon carbide composite material; or the aluminum-carbon-silicon raw material is a mixture of recycled corundum-silicon carbide composite material and erosion-resistant raw material, wherein the erosion-resistant raw material is one or a mixture of two or more of high-alumina bauxite, corundum, and silicon carbide; the rare earth oxide is scandium oxide and / or neodymium oxide. Compared with other rare earth oxides, the addition of scandium oxide can significantly reduce the reaction activation energy, promote grain refinement, improve its mechanical properties, and enhance its thermal shock resistance; neodymium oxide can form a solid solution with the matrix, which can not only effectively reduce the sintering temperature of the material, but also promote grain development and improve its mechanical properties.

[0010] The aforementioned aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles is composed of the following components in parts by weight: 10-25 parts by weight of high-alumina bauxite, 0-28 parts by weight of corundum, 0-6 parts by weight of silicon carbide, 28-76 parts by weight of recycled corundum silicon carbide composite material, 7-15 parts by weight of flake graphite, 2-3 parts by weight of composite antioxidant, 2-4 parts by weight of binder, and 0.5-1.5 parts by weight of rare earth oxides; the rare earth oxide is scandium oxide, and the corundum is one or a mixture of two or more of plate corundum, brown corundum, or white corundum.

[0011] The aforementioned aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles is composed of the following components in parts by weight: 10-25 parts by weight of high-alumina bauxite, 0-28 parts by weight of corundum, 0-6 parts by weight of silicon carbide, 28-76 parts by weight of recycled corundum silicon carbide composite material, 7-15 parts by weight of flake graphite, 2-3 parts by weight of composite antioxidant, 2-4 parts by weight of binder, and 0.5-2 parts by weight of rare earth oxides; the rare earth oxides are neodymium oxide, and the corundum is one or a mixture of two or more of plate corundum, brown corundum, or white corundum.

[0012] The aforementioned aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles is composed of the following components in parts by weight: 10-25 parts by weight of high-alumina bauxite, 0-28 parts by weight of corundum, 0-6 parts by weight of silicon carbide, 28-76 parts by weight of recycled corundum silicon carbide composite material, 7-15 parts by weight of flake graphite, 2-3 parts by weight of composite antioxidant, 2-4 parts by weight of binder, and 0.2-3.5 parts by weight of rare earth oxides; the corundum is one or a mixture of two or more of plate corundum, brown corundum, or white corundum; the rare earth oxides are a mixture of scandium oxide and neodymium oxide, with a mass ratio of scandium oxide to neodymium oxide of 1:(1-4). If the mass ratio of scandium oxide to neodymium oxide exceeds this range by too much, more low-melting-point substances will be formed, which will not only affect the sintering of the material but also reduce its mechanical properties.

[0013] The aluminum silicon carbide carbon bricks used for deep desulfurization of molten iron ladles have the following particle sizes: high-alumina bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm; corundum with a particle size greater than or equal to 1 mm and less than 3 mm; silicon carbide with a particle size less than or equal to 1 mm; flake graphite with a particle size less than or equal to 0.125 mm; rare earth oxides with a particle size less than or equal to 0.075 mm; and composite antioxidants with a particle size less than or equal to 0.15 mm.

[0014] The particle size distribution of the recycled corundum silicon carbide composite material for the above-mentioned aluminum silicon carbide carbon bricks used in deep desulfurization of molten iron ladles is as follows: 3-26 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 5-27 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 10-20 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 8-16 parts by weight of recycled corundum silicon carbide composite material with a particle size less than or equal to 0.15 mm. Using the recycled corundum silicon carbide composite material with this particle size distribution to replace part of the corundum in the preparation of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles can achieve a more ideal substitution effect. It will not only not affect the grade of the original formula product, but also significantly improve its oxidation resistance and thermal shock stability when a specific amount of rare earth oxides are added.

[0015] The particle size distribution of silicon carbide is as follows: 1 to 3 parts by weight of silicon carbide with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 1 to 6 parts by weight of silicon carbide with a particle size less than or equal to 0.15 mm.

[0016] The aforementioned silicon carbide carbon bricks used for deep desulfurization of molten iron ladles contain alumina content greater than or equal to 86 wt% in high-alumina bauxite and alumina content greater than or equal to 99 wt% in corundum, with a bulk density greater than or equal to 3.5 g / cm³. 3The silicon carbide content in the silicon carbide is greater than or equal to 95 wt%; the carbon content in the flake graphite is greater than or equal to 95 wt%; the binder is thermosetting phenolic resin (if a phosphate binder is used as the binder for the aluminum silicon carbide carbon brick for deep desulfurization of the molten iron ladle of this invention, its bonding strength and performance will decrease); the composite antioxidant is a mixture of metallic silicon powder and metallic aluminum powder in a mass ratio of (0.5-3):1; the mixing of silicon powder and aluminum powder in this ratio is beneficial to improving the high-temperature flexural strength of the material, and the composite antioxidant can play an antioxidant role at both medium and high temperatures, thereby effectively improving the high-temperature performance of the material; if the silicon powder and aluminum powder exceed this range, for example, if the proportion of silicon powder in the composite antioxidant is too low, the medium-temperature brick will oxidize too quickly, and the thermal shock resistance to spalling will decrease; if it is too high, the brick will form more low-melting phases, affecting its mechanical properties, and its cost will also increase;

[0017] The recycled corundum-silicon carbide composite material contains: aluminum oxide content greater than or equal to 41 wt%, silicon carbide content greater than or equal to 50 wt%, silicon dioxide content less than or equal to 5 wt%, magnesium oxide content less than or equal to 0.9 wt%, calcium oxide content less than or equal to 0.5 wt%, and the total content of sodium oxide and potassium oxide less than or equal to 0.6 wt%. The recycled corundum-silicon carbide composite material used in this invention was purchased commercially under the trade name "Recycled Corundum-Silicon Carbide Composite Board," model GYSC1, and was crushed to the required particle size after purchase.

[0018] A method for preparing an aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles includes the following steps:

[0019] Step A: Mix aluminum-carbon-silicon raw materials with a particle size greater than 100 mesh to obtain mixed dry material A;

[0020] Step B: Mix aluminum-carbon silicon raw materials with a particle size of less than or equal to 100 mesh, composite antioxidants and rare earth oxides to obtain mixed dry material B; Step A and Step B separate the granules with a particle size greater than 100 mesh and the powders with a particle size of less than or equal to 100 mesh for mixing, which can make the granules more easily encapsulated in the binder liquid phenolic resin after being fully mixed, and the powders more evenly distributed in the mixed materials.

[0021] Step C: After adding the binder to the dry mixture A and mixing evenly, continue to add flake graphite and dry mixture B in sequence and mix to obtain a mixture. Adding the flake graphite after the binder allows the flake graphite to be more evenly mixed with the granular material, binder, and liquid phenolic resin, reducing the agglomeration of the flake graphite. If the flake graphite is not mixed evenly, it will agglomerate and oxidize to form voids, reducing the oxidation resistance and mechanical properties of the final aluminum silicon carbide carbon brick.

[0022] Step D: Pour the mixture into a mold and press it to form a blank;

[0023] Step E: Dry and bake the billet. After drying, the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle is obtained.

[0024] In the above-mentioned preparation method of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles, in step C, the mixing and stirring time is 15-20 min; in step D, the molding pressure during pressing is 200-550 MPa, and the molding temperature is 15-40℃. Under these molding conditions, the mixture is easier to mold, and the resulting green body has moderate density. If the molding pressure is too high or too low, or the molding temperature is too low or too high, it will lead to agglomeration of the mixture or a loose green body; in step E, the drying and baking temperature is 180℃, and the drying time is 18-24 h. This preparation method of the present invention allows the aluminum silicon carbide carbon brick body to achieve resin hardening after drying. After hardening, the bonding strength between the clay and carbon network and between particles in the brick body can reach a high level, eliminating the need for high-temperature sintering, and thus obtaining deep desulfurization molten iron ladle bricks with ideal mechanical properties.

[0025] In the preparation method of the above-mentioned aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle, in step A: the mixed dry material A is composed of the following components in parts by weight: 20 parts by weight of high-alumina bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 15 parts by weight of corundum with a particle size greater than or equal to 1 mm and less than 3 mm, 3 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 13 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 2 parts by weight of silicon carbide with a particle size greater than 0.15 mm and less than or equal to 1 mm.

[0026] In step B: Mixed dry material B consists of the following components in parts by weight: 8.4 parts by weight of recycled corundum silicon carbide composite material with a particle size less than or equal to 0.15 mm, 2 parts by weight of silicon carbide with a particle size less than or equal to 0.15 mm, 12 parts by weight of flake graphite with a particle size less than or equal to 0.125 mm, 3 parts by weight of composite antioxidant with a particle size less than or equal to 0.15 mm, 0.8 parts by weight of scandium oxide with a particle size less than or equal to 0.075 mm, and 0.8 parts by weight of neodymium oxide with a particle size less than or equal to 0.075 mm; the composite antioxidant is a mixture of metallic silicon powder and metallic aluminum powder in a mass ratio of 2:1.

[0027] In step C: the binder is 3.2 parts by weight of liquid thermosetting phenolic resin; 12 parts by weight of flake graphite with a particle size less than or equal to 0.125 mm; the mixing time is 20 min.

[0028] In step D: the molding pressure during pressing is 280MPa and the molding temperature is 30℃; in step E: the drying time is 24h.

[0029] The technical solution of the present invention achieves the following beneficial technical effects:

[0030] 1. The recycled corundum-silicon carbide composite material used in this invention is a novel, low-cost raw material composed of fused alumina and high-purity silicon carbide. It is an upstream byproduct or a used high-temperature pure fused refractory material, thus allowing for recycling. It can replace brown corundum, sheet corundum, and silicon carbide in the preparation of carbon bricks for molten iron ladles. This invention utilizes the recycled corundum-silicon carbide composite material to prepare aluminum-silicon carbide carbon bricks for deep desulfurization in molten iron ladles, effectively reducing overall costs without significantly lowering the raw material grade. Simultaneously, it improves the oxidation resistance, thermal shock stability, and utilization rate of the recycled raw materials. This invention can largely or completely replace silicon carbide raw materials and sheet corundum aggregates, saving significant amounts of valuable resources such as high-grade corundum and high-purity silicon carbide.

[0031] 2. The aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles of the present invention uses high-alumina bauxite, recycled corundum silicon carbide composite material particles, and some corundum as the main raw materials, and adds flake graphite, composite antioxidant, scandium oxide, neodymium oxide and binder. The dosage of each component and the particle size distribution of the raw materials, especially the recycled corundum silicon carbide composite material particles, are adjusted. Through mixing and stirring, the resulting aluminum silicon carbide carbon brick has a low apparent porosity, an improved bulk density, and high compressive and flexural strength, which can meet the application requirements of bricks for deep desulfurization of molten iron ladles (desulfurization percentage greater than 50%).

[0032] 3. The aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared using the method of this invention exhibit oxidation resistance and thermal shock stability comparable to, or even exceeding, the original high-grade formulations. The preparation method of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles in this invention effectively reduces formulation costs, and the resulting deep desulfurization aluminum silicon carbide carbon bricks show significantly improved oxidation resistance and thermal shock stability compared to the original aluminum silicon carbide carbon bricks. Attached Figure Description

[0033] Figure 1 A schematic diagram of the middle part of silicon carbide and sintering agent in the recycled corundum silicon carbide composite material used in Example 1 of the present invention under an electron microscope.

[0034] Figure 2 Electron micrograph of the outer corundum and sintering agent of the recycled corundum silicon carbide composite material used in Example 1 of the present invention.

[0035] Figure 3Actual photograph of the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle prepared in Example 1 of this invention after 5 thermal shock tests;

[0036] Figure 4 Actual photograph of the aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared in Example 2 of this invention after 5 thermal shock tests;

[0037] Figure 5 Actual photograph of the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle prepared in Example 3 of this invention after 5 thermal shock tests;

[0038] Figure 6 Actual photograph of the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle prepared in Example 4 of this invention after 5 thermal shock tests;

[0039] Figure 7 Actual photograph of the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle prepared in Example 5 of this invention after 5 thermal shock tests;

[0040] Figure 8 The photograph shows the aluminum silicon carbide carbon bricks used for deep desulfurization of molten iron ladles prepared in Comparative Example 1 of this invention after 5 thermal shock tests. Detailed Implementation

[0041] Example 1

[0042] In this embodiment, the aluminum silicon carbide carbon brick used for deep desulfurization of molten iron ladle is composed of: 20 kg of high-alumina bauxite, 4 kg of silicon carbide, 63 kg of recycled corundum silicon carbide composite material, 10 kg of flake graphite, 3 kg of composite antioxidant and 3.2 kg of binder.

[0043] The recycled corundum silicon carbide composite material consists of 5 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 25 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 kg of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm (100 mesh) and less than or equal to 1 mm, and 13 kg of recycled corundum silicon carbide composite material particles with a particle size less than or equal to 0.15 mm.

[0044] The high-alumina bauxite has a particle size greater than or equal to 3 mm and less than or equal to 5 mm, and the alumina content in the high-alumina bauxite is greater than or equal to 86 wt%; the silicon carbide has a particle size less than or equal to 1 mm and a purity greater than or equal to 95 wt%; the flake graphite has a particle size less than or equal to 0.125 mm, and the carbon content in the flake graphite is greater than or equal to 95 wt%; the composite antioxidant has a particle size less than or equal to 0.15 mm.

[0045] The composite antioxidant is composed of 1.5 kg of metallic silicon powder and 1.5 kg of metallic aluminum powder; the binder is thermosetting liquid phenolic resin - refractory-specific phenolic resin 4630, purchased from Weilin New Material Technology Co., Ltd. The recycled corundum silicon carbide composite material was purchased from the market; its trade name is recycled corundum silicon carbide composite board, model and specification GYSC1. After purchase, it was crushed to the required particle size. In the recycled corundum silicon carbide composite material: the content of alumina is greater than or equal to 41 wt%, the content of silicon carbide is greater than or equal to 50 wt%, the content of silicon dioxide is less than or equal to 5 wt%, the content of magnesium oxide is less than or equal to 0.9 wt%, the content of calcium oxide is less than or equal to 0.5 wt%, and the total content of sodium oxide and potassium oxide is less than or equal to 0.6 wt%.

[0046] The preparation method of the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle in this embodiment includes the following steps:

[0047] Step A: Mix aluminum-carbon silicon raw materials with a particle size greater than 100 mesh (0.15 mm) to obtain mixed dry material A; In this embodiment, first mix 20 kg of high-alumina bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 5 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 25 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 kg of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 2 kg of silicon carbide with a particle size greater than 0.15 mm and less than or equal to 1 mm evenly to obtain mixed dry material A;

[0048] Step B: Mix aluminum-carbon silicon raw materials with a particle size of less than or equal to 100 mesh, composite antioxidants and rare earth oxides to obtain mixed dry material B; In this embodiment, 13 kg of recycled corundum silicon carbide composite material particles with a particle size of less than or equal to 0.15 mm, 2 kg of silicon carbide with a particle size of less than or equal to 0.15 mm and 3 kg of composite antioxidant with a particle size of less than or equal to 0.15 mm are mixed to obtain mixed dry material B;

[0049] Step C: Add 3.2 kg of liquid phenolic resin as binder to the dry mixture A and mix evenly. Then add 10 kg of flake graphite and dry mixture B in sequence and mix evenly in a mixing mill for 20 minutes to obtain the mixture.

[0050] Step D: Pour the mixture into a mold and press it into shape on a large 1000-ton friction brick press. The pressing pressure is 550MPa and the pressing temperature is 15℃ to obtain a green body.

[0051] Step E: Place the billet in a drying tunnel kiln for drying and baking at a temperature of 180°C for 24 hours. After drying, the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle in this embodiment is obtained.

[0052] Example 2

[0053] In this embodiment, the aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle is composed of: 17 kg of high-alumina bauxite, 15 kg of slab corundum, 4 kg of silicon carbide, 49 kg of recycled corundum silicon carbide composite material, 12 kg of flake graphite, 3 kg of composite antioxidant and 3.5 kg of binder.

[0054] The recycled corundum silicon carbide composite material consists of 8 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 15 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 10 kg of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm (100 mesh) and less than or equal to 1 mm, and 16 kg of recycled corundum silicon carbide composite material particles with a particle size less than or equal to 0.15 mm.

[0055] In this embodiment: the particle size of the tabular alumina is greater than or equal to 1 mm and less than 3 mm, the alumina content in the tabular alumina is greater than or equal to 99 wt%, and the bulk density is greater than or equal to 3.5 g / cm³. 3 The high-alumina bauxite, recycled corundum silicon carbide composite material, silicon carbide, flake graphite and binder used are exactly the same as in Example 1; the particle size of the composite antioxidant is less than or equal to 0.15 mm, and the composite antioxidant is made by mixing 2 kg of metallic silicon powder and 1.0 kg of metallic aluminum powder.

[0056] The preparation method of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladle in this embodiment differs from that in Example 1 except for the corresponding raw material dosage: in step C, the mixing time is 15 min; in step D, the molding pressure during pressing is 200 MPa and the molding temperature is 40℃; in step E, the drying time is 18 h.

[0057] Example 3

[0058] The aluminum silicon carbide carbon brick used for deep desulfurization of molten iron ladle in this embodiment is composed of: 20 kg of high-alumina bauxite, 23 kg of slab corundum, 4 kg of silicon carbide, 37.2 kg of recycled corundum silicon carbide composite material, 12 kg of flake graphite, 3 kg of composite antioxidant, 3.2 kg of binder and 0.8 kg of scandium oxide.

[0059] The recycled corundum silicon carbide composite material consists of 3 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 5 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 kg of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm (100 mesh) and less than or equal to 1 mm, and 9.2 kg of recycled corundum silicon carbide composite material particles with a particle size less than or equal to 0.15 mm.

[0060] In this embodiment: the high-alumina bauxite, recycled corundum silicon carbide composite material, plate corundum, silicon carbide, flake graphite, composite antioxidant and binder are all exactly the same as in Example 2; the particle size of scandium oxide is less than or equal to 0.075 mm.

[0061] The preparation method of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladle in this embodiment is the same as that in Example 2, except for the corresponding raw material dosage. In step B, scandium oxide is mixed with raw materials with a particle size of less than or equal to 100 mesh.

[0062] Example 4

[0063] In this embodiment, the aluminum silicon carbide carbon brick used for deep desulfurization of molten iron ladle is composed of: 20 kg of high-alumina bauxite, 15 kg of slab corundum, 4 kg of silicon carbide, 45.2 kg of recycled corundum silicon carbide composite material, 12 kg of flake graphite, 3 kg of composite antioxidant, 3.2 kg of binder and 0.8 kg of neodymium oxide.

[0064] The recycled corundum silicon carbide composite material consists of 3 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 13 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 kg of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm (100 mesh) and less than or equal to 1 mm, and 9.2 kg of recycled corundum silicon carbide composite material particles with a particle size less than or equal to 0.15 mm.

[0065] In this embodiment: the high-alumina bauxite, recycled corundum silicon carbide composite material, plate corundum, silicon carbide, flake graphite, composite antioxidant and binder are all exactly the same as in Example 2; the particle size of neodymium oxide is less than or equal to 0.075 mm.

[0066] The preparation method of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladle in this embodiment differs from that in Example 1 except for the corresponding raw material dosage: neodymium oxide is mixed with raw materials with a particle size of less than or equal to 100 mesh in step B; in step D, the molding pressure during pressing is 300 MPa and the molding temperature is 32°C; in step E, the drying time is 24 h.

[0067] Example 5

[0068] In this embodiment, the aluminum silicon carbide carbon brick used for deep desulfurization of molten iron ladle is composed of: 20 kg of high-alumina bauxite, 15 kg of slab corundum, 4 kg of silicon carbide, 44.4 kg of recycled corundum silicon carbide composite material, 12 kg of flake graphite, 3 kg of composite antioxidant, 3.2 kg of binder, 0.8 kg of scandium oxide, and 0.8 kg of neodymium oxide.

[0069] The recycled corundum silicon carbide composite material consists of 3 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 13 kg of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 kg of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm (100 mesh) and less than or equal to 1 mm, and 8.4 kg of recycled corundum silicon carbide composite material particles with a particle size less than or equal to 0.15 mm.

[0070] In this embodiment: the high-alumina bauxite, recycled corundum silicon carbide composite material, plate corundum, silicon carbide, flake graphite, composite antioxidant and binder are all exactly the same as in Example 2; the particle size of scandium oxide and neodymium oxide is less than or equal to 0.075 mm.

[0071] The preparation method of aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladle in this embodiment differs from that in Example 1 except for the corresponding raw material dosages: scandium oxide and neodymium oxide are mixed with raw materials with a particle size of less than or equal to 100 mesh in step B; in step D, the molding pressure during pressing is 280 MPa and the molding temperature is 30°C; in step E, the drying time is 24 h.

[0072] Comparative Example

[0073] The iron-clad brick of the comparative example of silicon carbide alumina carbon brick is composed of 77 kg of high-alumina bauxite, 10 kg of silicon carbide, 10 kg of flake graphite, 3 kg of composite antioxidant and 3.2 kg of binder.

[0074] The silicon carbide, composite antioxidant, and binder are exactly the same as in Example 1; the high-alumina bauxite consists of 23 kg of high-alumina bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 28 kg of high-alumina bauxite with a particle size greater than or equal to 1 mm and less than 3 mm, 10 kg of high-alumina bauxite with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 16 kg of high-alumina bauxite with a particle size less than or equal to 0.15 mm.

[0075] The preparation method is as follows: 77 kg of high-alumina bauxite, 10 kg of silicon carbide, 10 kg of flake graphite and 3 kg of composite antioxidant are first mixed to obtain a mixed dry material. Then, 3.2 kg of binder is added to the mixed dry material and mixed evenly to obtain a mixed material. The mixed material is pressed into a blank and dried and baked to obtain an iron-clad brick of aluminum silicon carbide carbon brick. The pressing and drying conditions are the same as those in Example 5.

[0076] The performance of the aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared in Examples 1 to 5 and the aluminum silicon carbide carbon bricks prepared in the comparative examples were tested. The test results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared in Examples 3 to 5 showed significantly improved compressive strength and flexural strength after 5 thermal shocks compared to Examples 1, 2 and Comparative Example 1, indicating a significant improvement in their thermal shock resistance.

[0080] Actual photographs of the aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared in Examples 1 to 5, and the aluminum silicon carbide carbon bricks prepared in the comparative example, after thermal shock tests are shown below. Figures 3 to 8 As can be seen from the figure, the iron ladle bricks prepared in the comparative example showed obvious spalling after 5 thermal shocks, while the aluminum silicon carbide carbon bricks for deep desulfurization of iron ladles in Examples 1 and 2 showed some improvement. The aluminum silicon carbide carbon bricks for deep desulfurization of iron ladles prepared in Examples 3 to 5 showed significant improvement, with more intact residues.

[0081] The above test results show that the aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared by the method of the present invention have a high-temperature flexural strength of about 8.5 MPa, which is significantly higher than the 5.0 MPa of the comparative example. The compressive strength after 5 thermal shocks reaches about 26.1 MPa, which is also significantly higher than the 15.2 MPa of the comparative example. The flexural strength after 5 thermal shocks is about 3.9 MPa, which is significantly higher than the 2.0 MPa of the comparative example. The samples with added scandium oxide and neodymium oxide have significantly improved thermal shock resistance and oxidation resistance compared with the previous samples. The samples with both added have better performance.

[0082] The aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles prepared in Example 2 were tested in a large steel plant. The results showed that the desulfurized molten iron ladles were used in 1351 heats, demonstrating high practical application value.

[0083] Obviously, the above embodiments are merely illustrative examples for clear explanation 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 here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. An aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladles, characterized in that, It is composed of aluminum-carbon-silicon raw materials, flake graphite, composite antioxidants, binders and rare earth oxides; The aluminum-carbon-silicon raw material is a mixture of recycled corundum-silicon carbide composite material and erosion-resistant raw material. The erosion-resistant raw material is one or a mixture of two or more of high-alumina bauxite, corundum and silicon carbide; the rare earth oxide is scandium oxide and / or neodymium oxide. The composition includes: 10-25 parts by weight of high-alumina bauxite, 0-28 parts by weight of corundum, 0-6 parts by weight of silicon carbide, 28-76 parts by weight of recycled corundum-silicon carbide composite material, 7-15 parts by weight of flake graphite, 2-3 parts by weight of composite antioxidant, and 2-4 parts by weight of binder. The corundum is one or a mixture of two or more of plate corundum, brown corundum, or white corundum. When the rare earth oxide is scandium oxide: 0.5-1.5 parts by weight of rare earth oxide; when the rare earth oxide is neodymium oxide: 0.5-2 parts by weight of rare earth oxide; when the rare earth oxide is a mixture of scandium oxide and neodymium oxide: 0.2-3.5 parts by weight of rare earth oxide, and the mass ratio of scandium oxide to neodymium oxide is 1:(1-4). In the recycled corundum-silicon carbide composite material: the content of alumina is greater than or equal to 41 wt%, the content of silicon carbide is greater than or equal to 50 wt%, the content of silicon dioxide is less than or equal to 5 wt%, the content of magnesium oxide is less than or equal to 0.9 wt%, the content of calcium oxide is less than or equal to 0.5 wt%, and the total content of sodium oxide and potassium oxide is less than or equal to 0.6 wt%; The composite antioxidant is a mixture of metallic silicon powder and metallic aluminum powder in a mass ratio of (0.5-3):

1.

2. The aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle according to claim 1, characterized in that, The particle size of high-alumina bauxite is greater than or equal to 3 mm and less than or equal to 5 mm; the particle size of corundum is greater than or equal to 1 mm and less than 3 mm; the particle size of silicon carbide is less than or equal to 1 mm; the particle size of flake graphite is less than or equal to 0.125 mm; the particle size of rare earth oxides is less than or equal to 0.075 mm; and the particle size of composite antioxidants is less than or equal to 0.15 mm.

3. The aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle according to claim 2, characterized in that, The particle size distribution of the recycled corundum silicon carbide composite material is as follows: 3-26 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 5-27 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 10-20 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 8-16 parts by weight of recycled corundum silicon carbide composite material with a particle size less than or equal to 0.15 mm. The particle size distribution of silicon carbide is as follows: 1 to 3 parts by weight of silicon carbide with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 1 to 6 parts by weight of silicon carbide with a particle size less than or equal to 0.15 mm.

4. The aluminum silicon carbide carbon brick for deep desulfurization of molten iron ladle according to claim 3, characterized in that, The alumina content in high-alumina bauxite is greater than or equal to 86 wt%; the alumina content in corundum is greater than or equal to 99 wt%, and the bulk density is greater than or equal to 3.5 g / cm³. 3 The silicon carbide content in the silicon carbide is greater than or equal to 95 wt%; the carbon content in the flake graphite is greater than or equal to 95 wt%; and the binder is thermosetting phenolic resin.

5. A method for preparing aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles as described in claim 3, characterized in that, Prepared using the following steps: Step A: Mix aluminum-carbon-silicon raw materials with a particle size greater than 100 mesh to obtain mixed dry material A; Step B: Mix aluminum-carbon-silicon raw materials with a particle size of less than or equal to 100 mesh, composite antioxidants and rare earth oxides to obtain mixed dry material B; Step C: After adding the binder to the mixed dry material A and mixing evenly, continue to add flake graphite and mixed dry material B in sequence and mix to obtain the mixed material; Step D: Pour the mixture into a mold and press it to form a blank; Step E: Dry and bake the billet. After drying, aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladle are obtained.

6. The method for preparing aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles according to claim 5, characterized in that, In step C, the mixing time is 15-20 min; in step D, the molding pressure during pressing is 200-550 MPa, and the molding temperature is 15-40℃; in step E, the drying and baking temperature is 180℃, and the drying time is 18-24 h.

7. The method for preparing aluminum silicon carbide carbon bricks for deep desulfurization of molten iron ladles according to claim 6, characterized in that, In step A: Mixed dry material A consists of the following components in parts by weight: 20 parts by weight of high-alumina bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 15 parts by weight of corundum with a particle size greater than or equal to 1 mm and less than 3 mm, 3 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 3 mm and less than or equal to 5 mm, 13 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than or equal to 1 mm and less than 3 mm, 20 parts by weight of recycled corundum silicon carbide composite material with a particle size greater than 0.15 mm and less than or equal to 1 mm, and 2 parts by weight of silicon carbide with a particle size greater than 0.15 mm and less than or equal to 1 mm. In step B: Mixed dry material B consists of the following components in parts by weight: 8.4 parts by weight of recycled corundum silicon carbide composite material with a particle size less than or equal to 0.15 mm, 2 parts by weight of silicon carbide with a particle size less than or equal to 0.15 mm, 12 parts by weight of flake graphite with a particle size less than or equal to 0.125 mm, 3 parts by weight of composite antioxidant with a particle size less than or equal to 0.15 mm, 0.8 parts by weight of scandium oxide with a particle size less than or equal to 0.075 mm, and 0.8 parts by weight of neodymium oxide with a particle size less than or equal to 0.075 mm; the composite antioxidant is a mixture of metallic silicon powder and metallic aluminum powder in a mass ratio of 2:

1. In step C: the binder is 3.2 parts by weight of liquid thermosetting phenolic resin; 12 parts by weight of flake graphite with a particle size less than or equal to 0.125 mm; the mixing time is 20 min. In step D: the molding pressure during pressing is 280MPa and the molding temperature is 30℃; in step E: the drying time is 24h.

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