A wall-cladding castable and preparation method thereof

Abstract

This invention relates to the field of refractory materials technology, and in particular to a wall-mounting castable. The raw materials of the wall-mounting castable comprise, by weight, the following components: 21-24 parts of corundum slag particles with a particle size of 5-8 mm; 13-16 parts of corundum slag particles with a particle size of 3-5 mm; 10-14 parts of corundum slag particles with a particle size of 1-3 mm; 10-14 parts of corundum slag particles with a particle size of 0.2-1 mm; 2-4 parts of air-quenched blast furnace slag aggregate with a particle size of 1-3 mm; and 0.2-1 mm of air-quenched blast furnace slag aggregate. The composition includes: 2-4 parts slag aggregate; 5-8 parts corundum slag powder with a particle size <0.074mm; 15-20 parts bauxite powder with a particle size <0.074mm; 5-8 parts activated alumina micro powder with a particle size <0.048mm; 1-3 parts silica micro powder with a particle size <0.074mm; 1-3 parts CA-50 calcium aluminate cement with a particle size <0.088mm; 0.1-0.3 parts sodium hexametaphosphate with a particle size <0.074mm; and 0.05-0.08 parts explosion-proof fiber. This invention also provides a method for preparing a wall-mounted castable: first, the raw materials are added to a mixer according to the weight ratio, mixed evenly, and then packaged.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, and in particular to a wall-mounted castable and its preparation method. Background Technology

[0002] A ladle is a container used for transporting molten steel and for ladle refining. It is an essential tool for transporting, refining, and casting molten steel in the process of connecting the converter to the continuous casting steelmaking process. The refractory lining of the ladle is usually divided into a working layer and a permanent layer. As an important component of the lining, the permanent layer is the last line of defense for the safe operation of the ladle and a reliable guarantee for maximizing the value of the working layer. It plays two main roles: first, insulation, especially the ladle wall. Because molten steel stays in the ladle for a long time, the permanent layer has good insulation properties, which can reduce the heat loss of the molten steel, lower the temperature of the ladle's steel structure shell, and extend its service life; second, a safety measure. When the working layer leaks steel or even melts to zero, the permanent layer can at least withstand the smelting of one heat of molten steel without causing the ladle to break through and leak.

[0003] In existing technologies, the permanent layer of the ladle wall is constructed using high-alumina bauxite bricks or integral casting technology. Chinese Patent Publication No. CN103449821A discloses a castable refractory for the permanent layer of a ladle, with the following weight percentages of raw material components: 40-50% sintered mullite, 10-15% fused mullite, 15-20% corundum, 5-10% ultrafine alumina powder, 5-10% ultrafine silica powder, 6-8% pure calcium aluminate cement, and 2.2-4.0% cenospheres. This refractory is mainly used for casting the permanent layer of the ladle. However, the high content of pure calcium aluminate cement makes it prone to failure at high temperatures, leading to a shortened lifespan of the permanent layer due to pulverization. The high content of low-melting-point materials causes shrinkage due to liquidation at high temperatures, resulting in cracks during repeated heating and cooling, thus reducing overall strength and causing faster damage, also affecting the service life of the permanent layer. Summary of the Invention

[0004] The purpose of this invention is to provide a wall-coating castable that can solve the above-mentioned technical problems. This invention also provides a method for preparing the wall-coating castable.

[0005] This invention provides a wall-mounting castable, the raw materials comprising the following components by weight:

[0006] 21-24 parts of corundum slag particles with a particle size of 5-8 mm;

[0007] 13-16 parts of corundum slag particles with a particle size of 3-5 mm;

[0008] 10-14 parts of corundum slag particles with a particle size of 1-3 mm;

[0009] 10-14 parts of corundum slag particles with a particle size of 0.2-1 mm;

[0010] 2-4 parts of air-quenched blast furnace slag aggregate with a particle size of 1-3mm;

[0011] 2-4 parts of air-quenched blast furnace slag aggregate with a particle size of 0.2-1mm;

[0012] 5-8 parts of corundum slag powder with a particle size of <0.074mm;

[0013] 15-20 parts of bauxite powder with a particle size of <0.074mm;

[0014] 5-8 parts of active alumina powder with a particle size of <0.048mm;

[0015] 1-3 parts of silica micropowder with a particle size of <0.074mm;

[0016] 1-3 parts of CA-50 calcium aluminate cement with a particle size of <0.088mm;

[0017] 0.1-0.3 parts of sodium hexametaphosphate with a particle size <0.074 mm;

[0018] 0.05-0.08 parts of explosion-proof fiber.

[0019] The end values ​​in the above ranges of 0.2-1, 1-3, 3-5, and 5-8 do not overlap, that is, 0.2-1 does not include 1, 1-3 does not include 3, and 3-5 does not include 5.

[0020] Preferably, the corundum slag particles are obtained by processing and crushing the by-product of ferrovanadium smelting, and contain, by weight, CaO: 10%-13%, Al2O3: 60%-70%, MgO: 13%-20%, H2O ≤ 0.5%, with a bulk density of 2.5-3.5 g / cm³. 3 .

[0021] Preferably, the air-quenched blast furnace slag aggregate is blast furnace slag produced by blast furnace ironmaking that is sprayed and granulated under high-speed airflow impact in a liquid state, and has a porous structure.

[0022] Preferably, the corundum slag powder is a by-product of vanadium-iron smelting, including a portion of the furnace lining carried over, and contains, by weight, CaO: 10%-13%, Al2O3: 30%-40%, MgO: 35%-45%, with the remainder being impurities.

[0023] Preferably, the bauxite powder contains ≥85% Al2O3 by weight.

[0024] Preferably, the active alumina powder is α-Al2O3 micro powder, with an Al2O3 content of ≥98% by weight.

[0025] Preferably, the silicon micropowder contains ≥90% SiO2 by weight.

[0026] Preferably, the explosion-proof fiber has a length of 5-7 mm and a melting point of 160±5℃.

[0027] The present invention also provides a method for preparing a wall-mounted castable: first, the raw materials are added to a mixer according to the weight ratio, mixed evenly, and then packaged.

[0028] Beneficial effects:

[0029] This invention utilizes Al2O3, CaO, and MgO from corundum slag to prepare microporous wall-coated castables. Furthermore, because the corundum slag contains some pre-melted Al2O3 and CaO, the amount of calcium aluminate cement required can be reduced. Additionally, the good sintering properties of corundum slag make the microporous wall-coated castables easier to sinter, thus improving the lifespan of the permanent layer. The invention also leverages the advantages of air-quenched blast furnace slag—light weight and good heat insulation and storage capacity—to enhance the thermal insulation performance of the castable. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Corundum slag is produced during the ferrovanadium smelting process and contains Al2O3, CaO (as a slag conditioner), MgO (brought in by furnace lining erosion), and a small amount of alloys. Currently, corundum slag users mainly use it for further vanadium extraction or to repair vanadium extraction refining furnaces. However, due to the continuous improvement of vanadium extraction technology, the vanadium content in corundum slag has gradually decreased, leading to a gradual decline in the vanadium extraction value of corundum slag.

[0034] Air-quenched blast furnace slag is molten blast furnace slag that is sprayed and granulated under the impact of high-speed airflow. It has high strength and porous structure, and has the advantages of light weight and good heat preservation. At the same time, the melting point of blast furnace slag is around 1300℃, so it can be used in the permanent layer of the cladding wall.

[0035] To avoid repetition, the raw materials involved in this specific embodiment are described uniformly as follows, and will not be repeated in the examples: Corundum slag particles are a by-product of vanadium-iron smelting, obtained by processing and crushing. By weight, they contain CaO: 10%-13%, Al2O3: 60%-70%, MgO: 13%-20%, H2O≤0.5%, and their bulk density is 2.5-3.5 g / cm³. 3 Air-quenched blast furnace slag is produced by blast furnace ironmaking and granulated under high-speed airflow impact in a liquid state; it has a porous structure. Corundum slag powder is a byproduct of vanadium-iron smelting, including some furnace lining material carried over; by weight, it contains 10%-13% CaO, 30%-40% Al2O3, and 35%-45% MgO, with the remainder being impurities. Bauxite powder is bauxite powder with an alumina grade of 85% or higher, containing ≥85% Al2O3 by weight. Activated alumina micropowder is α-Al2O3 micropowder containing ≥85% Al2O3 by weight. Al₂O₃ ≥ 98%; silica fume contains SiO₂ ≥ 90% by weight; CA-50 cement is a calcium aluminate cement, containing Al₂O₃ ≥ 50% and CaO < 25% by weight; sodium hexametaphosphate CAS number: 10124-56-8; explosion-proof fiber length 5-7mm, melting point 160±5℃. First, add the raw materials to the mixer according to the weight ratio, mix evenly, and then package.

[0036] The raw materials selected in this invention have the following functions:

[0037] Corundum slag and air-quenched blast furnace slag are used as aggregates. The main components of corundum slag are Al2O3, CaO, and MgO. During construction, it can provide initial strength and reduce the amount of cement used. At the same time, corundum slag is a pre-melted material, which makes the castable easier to sinter. The chemical composition of air-quenched blast furnace slag includes oxides such as Al2O3, SiO2, CaO, and MgO. The impurities are mainly oxides of alkali, alkaline earth, iron, and titanium. It has the characteristics of stable composition, uniform texture, and dense structure, which can provide high strength for castables, good thermal stability, good heat insulation effect, and light weight. The service temperature of air-quenched blast furnace slag can reach 1300℃. It is also a good lightweight high-temperature heat storage material.

[0038] The raw materials used include corundum slag powder, bauxite powder, activated alumina, and silica powder. Corundum slag powder, containing MgO and Al2O3, exhibits strong high-temperature resistance. The selected bauxite powder, primarily composed of alumina and silica, is a key raw material for unshaped refractories. The combined use of activated alumina and silica powder enhances the workability of the castable, and the addition of silica powder buffers expansion stress, improving the castable's strength, slag resistance, and high-temperature volume stability. The cement used is calcium aluminate-based CA-50 cement, with an alumina content of approximately 50%. This type of cement exhibits stable hydration properties, excellent mechanical strength, and a suitable strength enhancement, making it suitable for providing initial construction strength for microporous wall-mounted castables.

[0039] The additives are sodium hexametaphosphate and explosion-proof fibers. Sodium hexametaphosphate forms a dispersible gel with a small amount of water, enhancing the construction strength and improving the fluidity of the castable. The explosion-proof fibers are fine fibrous materials that permeate the various gaps in the castable, facilitating the release of water vapor during the baking process of the ladle tank and preventing water vapor from being trapped and causing pores to form.

[0040] Example 1:

[0041] The following materials will be used: 23 parts by weight of 5-8mm corundum slag particles, 15 parts by weight of 3-5mm corundum slag particles, 12 parts by weight of 1-3mm corundum slag, 11 parts by weight of 0-1mm corundum slag, 3 parts by weight of 1-3mm air-quenched blast furnace slag, 3 parts by weight of 0.2-1mm air-quenched blast furnace slag; 6 parts by weight of <0.074mm corundum slag powder, 16 parts by weight of <0.074mm bauxite powder, 6 parts by weight of <0.048mm activated alumina micro powder, 2 parts by weight of <0.074mm silica micro powder, 3 parts by weight of <0.088mm CA-50 calcium aluminate cement; plus 0.2 parts by weight of sodium hexametaphosphate and 0.08 parts by weight of explosion-proof fiber (the above weight units are kg, t, etc., and can be freely selected according to the actual situation). The mixture is fed into a drum mixer for mixing. After mixing for 4 minutes, the homogenized material is discharged through a three-way valve into dry ton bags, packaged in 500 kg bags, and the opening is sealed for storage. Samples are taken to test the physicochemical properties of the microporous wall-mounted castable. The test method for bulk density is YB / T5200, the test method for flexural strength is GB / T13243, the test method for compressive strength is YB / T5201, and the test method for linear change is YB / T5203 (test results are shown in Table 1). After passing the tests, the material is transported to the repair and maintenance area of ​​a steel plant.

[0042] Table 1. Physicochemical test indicators of microporous wall-wrapped casting in Example 1

[0043] project Test results % <![CDATA[Apparent density, g / cm 3 (110 * 24 h)]]> 2.1 Flexural strength, MPa (1400*3h) 6.6 Pressure resistance, MPa (110*24h) 36 Pressure resistance, MPa (1400*3h) 53 Linear change rate, % (1400*3h) 0.15

[0044] The bulk density of the microporous castable in this embodiment is 2.1 g / cm³. 3 As a refractory material for steel ladle walls, it was delivered to the repair and maintenance area of ​​a steel plant. The uniformly mixed bulk material was added to a mixer, along with 6-7 wt% water, and stirred for 3-4 minutes until it exhibited good fluidity. This mixture was then poured into the ladle lid and vibrated to form the final shape. After curing at room temperature for 24-48 hours, it was ready for online baking and use. The water-reducing agent used in this example was a polycarboxylate superplasticizer.

[0045] Two steel ladles were used, with a total refractory refractory consumption of 26 tons. Data collected from construction to overhaul showed that the microporous ladle wall refractory performed well, with no material loss or cracking occurring during curing. During online use, the permanent layer of the ladle wall achieved 7 and 8 service cycles respectively, compared to the original refractory's average of 5-6 service cycles, indicating an improved lifespan. The temperature drop during the refining furnace process after tapping was 5.9℃, compared to the original refractory's 6.5℃ drop, demonstrating better insulation. The temperature drop during the tundish-refining furnace process was 4.1℃, compared to the original refractory's 4.9℃ drop, showing a slight improvement in insulation. The original refractory, by weight percentage, consisted of: 75% high-alumina bauxite, 10% cement, 5% ultrafine silica powder, 1% sodium polyphosphate, 5% metallic aluminum, and 4% explosion-proof fiber.

[0046] Example 2:

[0047] The following materials were selected: 21 parts by weight of 5-8mm corundum slag particles, 13 parts by weight of 3-5mm corundum slag particles, 12 parts by weight of 1-3mm corundum slag, 11 parts by weight of 0-1mm corundum slag, 4 parts by weight of 1-3mm air-quenched blast furnace slag, 4 parts by weight of 0.2-1mm air-quenched blast furnace slag, 8 parts by weight of <0.074mm corundum slag powder, 17 parts by weight of <0.074mm bauxite powder, 6 parts by weight of <0.048mm active alumina micro powder, 2 parts by weight of <0.074mm silica micro powder, 2 parts by weight of <0.088mm CA-50 calcium aluminate cement, plus 0.2 parts by weight of sodium hexametaphosphate and 0.08 parts by weight of explosion-proof fiber. The mixture is fed into a drum mixer for mixing. After mixing for 4 minutes, the homogenized material is discharged through a three-way valve into dry ton bags, packaged at 500 kg / bag, and the opening is sealed for storage. Samples are taken to test the physicochemical properties of the microporous wall-mounted castable. The test methods for each physicochemical property are the same as in Example 1 (test results are shown in Table 2). After passing the tests, the material is transported to the repair and maintenance area of ​​a steel plant.

[0048] Table 2. Physicochemical test indicators of microporous wall-wrapped casting in Example 2

[0049] project Test results % <![CDATA[Apparent density, g / cm 3 (110 * 24 h)]]> 1.9 Flexural strength, MPa (1400*3h) 6.1 Pressure resistance, MPa (110*24h) 33 Pressure resistance, MPa (1400*3h) 48 Linear change rate, % (1400*3h) 0.14

[0050] The bulk density of the microporous castable in this embodiment is 1.9 g / cm³. 3 As a refractory material for steel ladle walls, it was delivered to the repair and maintenance area of ​​a steel plant. The uniformly mixed bulk material was added to a mixer, along with 6-7 wt% water, and stirred for 3-4 minutes until it exhibited good fluidity. This mixture was then poured into the ladle lid and vibrated to form the final shape. After curing at room temperature for 24-48 hours, it was ready for online baking and use. The water-reducing agent used in this example was a polycarboxylate superplasticizer.

[0051] One steel ladle was used, with a refractory consumption of 12.5 tons. Data collected from construction to overhaul showed that the microporous ladle wall refractory performed well during construction, with no material loss or cracking occurring during curing. During online use, the permanent layer of the ladle wall achieved 7 service cycles, compared to the original refractory's average of 5-6 service cycles, indicating an improved lifespan. The temperature drop from tapping to refining furnace was 5.3℃, compared to the original refractory's 6.5℃ drop, demonstrating better insulation. The temperature drop from refining furnace to tundish was 3.8℃, compared to the original refractory's 4.9℃ drop, showing a slight improvement in insulation. The original refractory was the same as in Example 1.

[0052] The following materials were selected: 22 parts by weight of 5-8mm corundum slag particles, 14 parts by weight of 3-5mm corundum slag particles, 13 parts by weight of 1-3mm corundum slag, 13 parts by weight of 0-1mm corundum slag, 2 parts by weight of 1-3mm air-quenched blast furnace slag, 2 parts by weight of 0.2-1mm air-quenched blast furnace slag, 7 parts by weight of <0.074mm corundum slag powder, 17 parts by weight of <0.074mm bauxite powder, 6 parts by weight of <0.048mm activated alumina micro powder, 2 parts by weight of <0.074mm silica micro powder, 2 parts by weight of <0.088mm CA-50 calcium aluminate cement, plus 0.2 parts by weight of sodium hexametaphosphate and 0.08 parts by weight of explosion-proof fiber. The mixture is fed into a drum mixer for mixing. After mixing for 4 minutes, the mixed material is discharged through a three-way valve into dry ton bags, packaged at 500 kg / bag, and the opening is sealed for storage. Samples are taken to test the physicochemical properties of the microporous wall-mounted castable. The test methods for each physicochemical property are the same as in Example 1 (test results are shown in Table 3). After passing the tests, the material is transported to the repair and maintenance area of ​​a steel plant.

[0053] Table 3. Physicochemical test indicators of microporous wall-wrapped casting in Example 3

[0054] project Test results % <![CDATA[Apparent density, g / cm 3 (110 * 24 h)]]> 2.3 Flexural strength, MPa (1400*3h) 6.9 Pressure resistance, MPa (110*24h) 37 Pressure resistance, MPa (1400*3h) 56 Linear change rate, % (1400*3h) 0.16

[0055] The bulk density of the microporous castable in this embodiment is 2.3 g / cm³. 3As a refractory material for steel ladle walls, it was delivered to the repair and maintenance area of ​​a steel plant. The uniformly mixed bulk material was added to a mixer, along with 6-7 wt% water, and stirred for 3-4 minutes until it exhibited good fluidity. This mixture was then poured into the ladle lid and vibrated to form the final shape. After curing at room temperature for 24-48 hours, it was ready for online baking and use. The water-reducing agent used in this example was a polycarboxylate superplasticizer.

[0056] Two steel ladles were used, with a total refractory consumption of 28 tons. Data collected from construction to overhaul showed that the microporous ladle wall refractory performed well, with no material loss or cracking occurring during curing. During online use, the permanent layer of the ladle wall achieved 8 service cycles, compared to the original refractory's average of 5-6 service cycles, indicating an improved lifespan. The temperature drop from tapping to the refining furnace was 6.1℃, compared to the original refractory's 6.5℃ drop, demonstrating better insulation. The temperature drop from the refining furnace to the tundish was 4.3℃, compared to the original refractory's 4.9℃ drop, showing a slight improvement in insulation. The original refractory was the same as in Example 1.

[0057] Based on the background technology and the contents of Embodiments 1, 2, and 3 of the present invention, it can be concluded that the microporous wall-mounting castable of the present invention has good application performance and construction on the ladle wall, significantly extends its online service life, and has a good heat preservation effect. The application of the present invention can effectively alleviate the phenomenon of spalling of the ladle wall castable during online use, reduce the fluctuation of molten steel temperature, and bring favorable effects to the steelmaking plant in terms of energy conservation, emission reduction, and cost reduction, with broad application prospects.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of wall-mounted castable, characterized in that, The raw materials include the following components by weight: 21-24 parts of corundum slag particles with a particle size of 5-8 mm; 13-16 parts of corundum slag particles with a particle size of 3-5 mm; 10-14 parts of corundum slag particles with a particle size of 1-3 mm; 10-14 parts of corundum slag particles with a particle size of 0.2-1 mm; 2-4 parts of air-quenched blast furnace slag aggregate with a particle size of 1-3mm; 2-4 parts of air-quenched blast furnace slag aggregate with a particle size of 0.2-1mm; 5-8 parts of corundum slag powder with a particle size of <0.074mm; 15-20 parts of bauxite powder with a particle size of <0.074mm; 5-8 parts of active alumina micro powder with a particle size of <0.048mm; 1-3 parts of silica micropowder with a particle size of <0.074mm; 1-3 parts of CA-50 calcium aluminate cement with a particle size of <0.088mm; 0.1-0.3 parts of sodium hexametaphosphate with a particle size <0.074 mm; 0.05-0.08 parts of explosion-proof fiber; The corundum slag particles are obtained by processing and crushing a by-product of vanadium-iron smelting. By weight, they contain 10%-13% CaO, 60%-70% Al2O3, 13%-20% MgO, and ≤0.5% H2O, with a bulk density of 2.5-3.5 g / cm³. 3 ; The air-quenched blast furnace slag aggregate is blast furnace slag produced by blast furnace ironmaking that is sprayed and granulated under high-speed airflow impact in a liquid state, and has a porous structure. The corundum slag powder is a by-product of vanadium-iron smelting, including a portion of the furnace lining carried over. By weight, it contains CaO: 10%-13%, Al2O3: 30%-40%, MgO: 35%-45%, with the remainder being impurities.

2. The wall-mounted castable refractory according to claim 1, characterized in that, The bauxite powder contains ≥85% Al2O3 by weight.

3. The wall-mounted castable refractory according to claim 1, characterized in that, The active alumina powder is α-Al2O3 micro powder, with an Al2O3 content of ≥98% by weight.

4. The wall-mounted castable according to claim 1, characterized in that, The silicon micropowder contains ≥90% SiO2 by weight.

5. The wall-mounting castable according to claim 1, characterized in that, The explosion-proof fiber has a length of 5-7 mm and a melting point of 160±5℃.

6. A method for preparing a wall-mounted castable according to any one of claims 1-5, characterized in that: First, add the raw materials to the mixer according to the weight ratio, mix them evenly, and then package them.