Steel ladle castable and preparation method thereof

Abstract

The invention relates to the technical field of castable, and provides a steel ladle castable and a preparation method thereof. The steel ladle castable is prepared from the following components in parts by weight: 72 to 95 parts of fused corundum, 2 to 5 parts of magnesite clinker, 1 to 5 parts of fused magnesia, 4.5 to 6 parts of calcium aluminate cement, 2 to 3 parts of silica powder, 0.05 to 0.15 part of sodium tripolyphosphate, 0.1 to 0.2 part of sodium hexametaphosphate, 4 to 6 parts of zirconite, 1 to 8 parts of composite expanded graphite, 3 to 5 parts of phenolic resin and 3 to 5 parts of chelating agent, the scale sizes of the first expanded graphite and the second expanded graphite are different. According to the technical scheme, the problem that in the prior art, due to the secondary mullitization phenomenon caused by zirconite decomposition, the castable structure becomes loose, and the erosion resistance and the thermal shock resistance of the steel ladle castable are weakened is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of castables, and in particular to a ladle castable and a preparation method thereof. Background Art

[0002] As a core thermal equipment in the steelmaking process, the ladle undertakes the crucial task of receiving, transporting, and refining high-temperature molten steel. Operating under extremely high temperatures of 1500°C to 1700°C, the ladle must not only withstand the intense erosion of molten steel and slag, but also resist chemical attack, creating extremely demanding operating conditions. The castable used in the ladle lining, a key material for ensuring safe and stable ladle operation, directly impacts steel quality, production efficiency, and steelmaking costs. Currently, commonly used ladle castables include clay, spinel, and corundum.

[0003] To enhance the corrosion resistance and thermal shock stability of ladle castables, the industry often introduces zircon as an additive into the material system. During the firing process, the decomposition of zircon produces fine zirconium dioxide grains that can enhance toughness and viscosity, improving material performance to a certain extent. However, at the same time, the secondary mullite formation caused by decomposition causes the material structure to become loose, which in turn weakens its corrosion resistance. This contradiction between performance improvement and loss makes the development of new ladle castables with excellent corrosion resistance and thermal shock stability a key issue that the industry urgently needs to address. Therefore, it is necessary to propose a ladle castable with excellent corrosion resistance and thermal shock stability. Summary of the Invention

[0004] The present invention provides a ladle castable and a preparation method thereof, which solves the problem in the prior art that secondary mullite formation caused by zircon decomposition causes the castable structure to become loose, thereby weakening its corrosion resistance and thermal shock resistance.

[0005] The technical solutions of the present invention are as follows: The present invention provides a ladle castable, comprising the following components in parts by weight: 72-95 parts of fused corundum, 2-5 parts of sintered magnesia, 1-5 parts of fused magnesia, 4.5-6 parts of calcium aluminate cement, 2-3 parts of silica powder, 0.05-0.15 parts of sodium tripolyphosphate, 0.1-0.2 parts of sodium hexametaphosphate, 4-6 parts of zircon, 1-8 parts of composite expanded graphite, 3-5 parts of phenolic resin, and 3-5 parts of a chelating agent. The composite expanded graphite comprises a first expanded graphite and a second expanded graphite, and the flake sizes of the first expanded graphite and the second expanded graphite are different.

[0006] As a further technical solution, the first expanded graphite has a flake size of 0.05 mm, and the second expanded graphite has a flake size of 0.07 mm. The combination of expanded graphite with a flake size of 0.05 mm and expanded graphite with flake sizes of 0.07 mm and 0.05 mm in the ladle castable of the present invention optimizes the pore structure through particle size grading, with small flakes filling the gaps between large flakes to form a denser network, improve the overall density of the material, and enhance the thermal shock resistance and corrosion resistance of the ladle castable.

[0007] As a further technical solution, when the mass ratio of the first expanded graphite to the second expanded graphite is 3:3-6, the filling effect of the composite expanded graphite can be further improved, and the thermal shock resistance and corrosion resistance of the ladle castable can be further improved.

[0008] As a further technical solution, the fused corundum includes the following components in parts by weight: 12 to 15 parts of fused corundum with a particle size of 0 μm < particle size < 3 μm, 13 to 17 parts of fused corundum with a particle size of 3 μm ≤ particle size < 5 μm, 15 to 19 parts of fused corundum with a particle size of 5 μm ≤ particle size < 10 μm, 18 to 23 parts of fused corundum with a particle size of 10 μm ≤ particle size ≤ 25 μm, 6 to 9 parts of fused corundum with a particle size of 45 μm, and 8 to 12 parts of fused corundum with a particle size of 74 μm.

[0009] The present invention uses a compound of fused corundum of different particle sizes in the ladle casting material, and optimizes performance through particle size grading: large particles serve as a skeleton, and small and medium particles fill pores, thereby increasing the density and strength of the ladle casting material, improving workability, avoiding the defects of a single particle size, achieving performance synergy, and reducing costs.

[0010] As a further technical solution, the components of the ladle castable further include 2 to 5 parts of a composite catalyst, and the composite catalyst consists of ferrocene and nano iron powder.

[0011] The expanded graphite added to the ladle castable of the present invention has a large number of unique network-like microporous structures, providing sufficient space for in-situ generation of carbon nanotubes. The catalyst can catalyze the cracking of phenolic resin to generate carbon nanotubes in situ on the surface of the expanded graphite. The carbon nanotubes can reduce the internal thermal stress gradient of the castable due to their high thermal conductivity, and their high strength and flexibility can inhibit crack propagation through effects such as bridging, thereby improving the thermal shock resistance of the material. The composite catalyst composed of ferrocene and carbon nanopowder can further improve the thermal shock resistance of the ladle castable. The reason is that when ferrocene is compounded with nano iron powder as a catalyst, the ferrocene decomposes at high temperature to continuously release iron atoms to supplement active sites, forming a "dynamic iron supply" mechanism with the nano iron powder. At the same time, the carbon source generated by its decomposition can directly participate in the growth of carbon nanotubes, improve the nucleation density, further promote the reaction of in-situ generation of carbon nanotubes, and further improve the thermal shock resistance of the ladle castable through the synergistic effect of expanded graphite and carbon nanotubes.

[0012] As a further technical solution, the weight portion of the composite catalyst is 3 parts.

[0013] As a further technical solution, the particle size of the nano iron powder is 40-60 nm.

[0014] When the particle size of the catalyst iron powder is less than 40nm, it is easy to cause the iron powder to agglomerate; when the particle size of the catalyst iron powder is greater than 60nm, there are fewer active sites and the nucleation efficiency is low; when the particle size of the catalyst iron powder is 40~60nm, the specific surface area is larger and there are more active sites, which is conducive to the nucleation of carbon nanotubes.

[0015] As a further technical solution, when the mass ratio of ferrocene to nano iron powder is 1-3:3, the catalytic efficiency of the composite catalyst can be further improved.

[0016] As a further technical solution, the chelating agent is an organic carboxylic acid chelating agent, including one or more of citric acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid.

[0017] The present invention also provides a method for preparing a ladle castable, comprising the following steps: S1. Mix the components uniformly to obtain a mixed aggregate; S2. After the mixed aggregate and water are evenly mixed, the mixture is placed in a mold and cast into shape. After demoulding and drying, the green body is sintered to obtain the ladle castable.

[0018] As a further technical solution, the mass ratio of the mixed aggregate to water is 10:1.

[0019] As a further technical solution, during sintering in step S2, the green body is first heated to 400°C at a rate of 15°C / min, kept warm for 1 hour, and then heated to 850-950°C at a rate of 10°C / min. Keeping warm for 2-4 hours can increase the decomposition rate of ferrocene, thereby enabling better growth of carbon nanotubes.

[0020] The working principle and beneficial effects of the present invention are: The ladle castable prepared from fused corundum, sintered magnesia, fused magnesia, calcium aluminate cement, silica powder, sodium tripolyphosphate, sodium hexametaphosphate, zircon, composite expanded graphite, phenolic resin, and a chelating agent has high corrosion resistance and thermal shock resistance. The composite expanded graphite includes a first expanded graphite and a second expanded graphite of different flake sizes. The composite expanded graphites of different flake sizes are compounded and added to the castable, enabling multi-level pore filling with large flakes forming a skeleton and small flakes filling gaps, thereby improving the material structure density and enhancing the castable's corrosion resistance and thermal shock resistance. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] In the following embodiments and comparative examples, sintered magnesia (particle size of 0-0.5 μm), fused magnesia (particle size of 74 μm), calcium aluminate cement CA75 (purchased from Zhengzhou Jinghua Special Cement Co., Ltd.), silica powder (particle size of 44 μm, purity of 97%), zircon (ZrO2 content of 67.2%, SiO2 content of 32.8%, particle size of 44 μm), phenolic resin FRJ-551, and nano iron powder (particle size of 50 nm) were used.

[0023] Example 1 A ladle castable comprises the following components in parts by weight: 12 parts of fused corundum with a particle size of 0 μm < particle size < 3 μm, 13 parts of fused corundum with a particle size of 3 μm ≤ particle size < 5 μm, 15 parts of fused corundum with a particle size of 5 μm ≤ particle size < 10 μm, 18 parts of fused corundum with a particle size of 10 μm ≤ particle size ≤ 25 μm, 6 parts of fused corundum with a particle size of 45 μm, 8 parts of fused corundum with a particle size of 74 μm, 2 parts of sintered magnesia parts, 1 part of fused magnesia, 4.5 parts of calcium aluminate cement, 2 parts of silica powder, 0.05 parts of sodium tripolyphosphate, 0.1 parts of sodium hexametaphosphate, 4 parts of zircon, 1 part of composite expanded graphite, 3 parts of phenolic resin, and 3 parts of citric acid; wherein the composite expanded graphite is composed of a first expanded graphite and a second expanded graphite in a mass ratio of 1:1, the flake size of the first expanded graphite is 0.05 mm, and the flake size of the second expanded graphite is 0.07 mm; A method for preparing a ladle castable comprises the following steps: S1. Mix the components uniformly to obtain a mixed aggregate; S2. After uniformly mixing the mixed aggregate and water, put them into a mold and cast them into shape. After demolding and drying, the green body is sintered to obtain a ladle castable. During sintering, the green body is first heated to 400°C at a rate of 10°C / min and kept warm for 1 hour, then heated to 850°C at a rate of 10°C / min and kept warm for 4 hours. The sintering atmosphere is nitrogen. The mass ratio of the mixed aggregate to water is 10:1.

[0024] Example 2 A ladle castable comprises the following components in parts by weight: 14 parts of fused corundum with a particle size of 0 μm < particle size < 3 μm, 15 parts of fused corundum with a particle size of 3 μm ≤ particle size < 5 μm, 17 parts of fused corundum with a particle size of 5 μm ≤ particle size < 10 μm, 21 parts of fused corundum with a particle size of 10 μm ≤ particle size ≤ 25 μm, 8 parts of fused corundum with a particle size of 45 μm, 10 parts of fused corundum with a particle size of 74 μm, 3 parts of sintered magnesia, 4 parts of fused magnesia, 5.5 parts of calcium aluminate cement, 2.5 parts of silica powder, 0.1 part of sodium tripolyphosphate, 0.15 part of sodium hexametaphosphate, 5 parts of zircon, 5 parts of composite expanded graphite, 4 parts of phenolic resin, and 4 parts of ethylenediaminetetraacetic acid; wherein the composite expanded graphite is composed of a first expanded graphite and a second expanded graphite in a mass ratio of 1:1, the flake size of the first expanded graphite is 0.05 mm, and the flake size of the second expanded graphite is 0.07 mm; A method for preparing a ladle castable comprises the following steps: S1. Mix the components uniformly to obtain a mixed aggregate; S2. After uniformly mixing the mixed aggregate and water, put them into a mold and cast them into shape. After demolding and drying, the green body is sintered to obtain a ladle castable. During sintering, the green body is first heated to 400°C at a rate of 10°C / min and kept warm for 1 hour, then heated to 900°C at a rate of 10°C / min and kept warm for 3 hours. The sintering atmosphere is nitrogen, and the mass ratio of the mixed aggregate to water is 10:1.

[0025] Example 3 A ladle castable comprises the following components in parts by weight: 15 parts of fused corundum with a particle size of 0 μm < particle size < 3 μm, 17 parts of fused corundum with a particle size of 3 μm ≤ particle size < 5 μm, 19 parts of fused corundum with a particle size of 5 μm ≤ particle size < 10 μm, 23 parts of fused corundum with a particle size of 10 μm ≤ particle size ≤ 25 μm, 9 parts of fused corundum with a particle size of 45 μm, 12 parts of fused corundum with a particle size of 74 μm, and 5 parts of sintered magnesia. , 5 parts of fused magnesia, 6 parts of calcium aluminate cement, 3 parts of silica powder, 0.15 parts of sodium tripolyphosphate, 0.2 parts of sodium hexametaphosphate, 6 parts of zircon, 8 parts of composite expanded graphite, 5 parts of phenolic resin, and 5 parts of diethylenetriaminepentaacetic acid; wherein the composite expanded graphite is composed of a first expanded graphite and a second expanded graphite in a mass ratio of 1:1, the flake size of the first expanded graphite is 0.05 mm, and the flake size of the second expanded graphite is 0.07 mm; A method for preparing a ladle castable comprises the following steps: S1. Mix the components uniformly to obtain a mixed aggregate; S2. After the mixed aggregate and water are evenly mixed, they are placed in a mold and cast into shape. After demolding and drying, the green body is sintered to obtain a ladle castable. During sintering, the green body is first heated to 400°C at a rate of 10°C / min and kept warm for 1 hour, then heated to 950°C at a rate of 10°C / min and kept warm for 2 hours. The sintering atmosphere is nitrogen, and the mass ratio of the mixed aggregate to water is 10:1.

[0026] Example 4 The only difference between this embodiment and embodiment 2 is that the composite expanded graphite is composed of the first expanded graphite and the second expanded graphite in a mass ratio of 3:5.

[0027] Example 5 The only difference between this embodiment and embodiment 2 is that the composite expanded graphite is composed of the first expanded graphite and the second expanded graphite in a mass ratio of 1:2.

[0028] Example 6 The only difference between this embodiment and embodiment 2 is that the components of the ladle castable in this embodiment further include 3 parts of a composite catalyst; wherein the composite catalyst is composed of ferrocene and nano iron powder in a mass ratio of 1:3.

[0029] Example 7 The only difference between this embodiment and embodiment 6 is that the composite catalyst in this embodiment is composed of ferrocene and nano iron powder in a mass ratio of 2:3.

[0030] Example 8 The only difference between this embodiment and embodiment 6 is that the composite catalyst in this embodiment is composed of ferrocene and nano iron powder in a mass ratio of 1:1.

[0031] Example 9 The only difference between this embodiment and embodiment 6 is that the composite catalyst in this embodiment is only ferrocene.

[0032] Example 10 The only difference between this embodiment and embodiment 6 is that the composite catalyst in this embodiment is only nano iron powder.

[0033] Example 11 The only difference between this embodiment and embodiment 7 is that, during sintering in this embodiment, the green body is first heated to 400°C at a rate of 20°C / min and kept at that temperature for 1 hour, and then heated to 900°C at a rate of 10°C / min and kept at that temperature for 3 hours.

[0034] Example 12 The only difference between this embodiment and embodiment 7 is that, during sintering in this embodiment, the green body is first heated to 400°C at a rate of 15°C / min, kept at that temperature for 1 hour, and then heated to 900°C at a rate of 10°C / min, kept at that temperature for 3 hours.

[0035] Comparative Example 1 The only difference between this comparative example and Example 2 is that the composite expanded graphite in this example consists only of the first expanded graphite.

[0036] Comparative Example 2 The only difference between this comparative example and Example 2 is that the composite expanded graphite in this example consists only of the second expanded graphite.

[0037] Comparative Example 3 The only difference between this comparative example and Example 2 is that this example does not contain composite expanded graphite.

[0038] The ladle castables prepared in Examples 1 to 12 and Comparative Examples 1 to 3 were tested according to the following method: 1. Thermal shock resistance: Test the thermal shock resistance of the sample in accordance with Method 1: Water quenching method - straight brick specimen method specified in GB / T 30873-2014 "Test method for thermal shock resistance of refractory materials"; 2. Slag erosion resistance: According to the provisions of GB / T8931-2007 "Test method for slag resistance of refractory materials", the slag erosion rate of the sample is tested by the static sample slag immersion and ventilation method; The test results are shown in the following table: Table 1 Performance measurement results of ladle castables in Examples 1 to 5 and Comparative Examples 1 to 3

[0039] Table 2 Performance test results of ladle castables in Examples 2, 6 to 12

[0040] The data in Tables 1 and 2 show that the ladle castables prepared in the present invention have high thermal shock resistance and good slag erosion resistance. A comparison of Example 1 with Comparative Examples 1 to 3 shows that the addition of the first and second expanded graphites significantly improves the thermal shock resistance and slag erosion resistance of the ladle castable. A comparison of Example 2 with Examples 4 and 5 shows that when the composite expanded graphite comprises the first and second expanded graphites in a mass ratio of 3:5, the thermal shock resistance and slag erosion resistance of the ladle castable are further improved. A comparison of Example 2 with Examples 6 to 10 shows that the addition of ferrocene and nano-iron powder as a composite catalyst significantly improves the thermal shock resistance of the ladle castable, and when the composite catalyst comprises ferrocene and nano-iron powder in a mass ratio of 2:3, the thermal shock resistance of the ladle castable is further enhanced. Comparison between Example 7 and Examples 11-12 shows that during sintering, the thermal shock resistance of the ladle castable can be further improved by first heating the green body to 400°C at a rate of 15°C / min, holding it for 1 hour, and then heating it to 850-950°C at a rate of 10°C / min and holding it for 2-4 hours.

[0041] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A ladle castable, characterized in that: The invention comprises the following components in parts by weight: 72-95 parts of fused corundum, 2-5 parts of sintered magnesia, 1-5 parts of fused magnesia, 4.5-6 parts of calcium aluminate cement, 2-3 parts of silicon micropowder, 0.05-0.15 parts of sodium tripolyphosphate, 0.1-0.2 parts of sodium hexametaphosphate, 4-6 parts of zircon, 1-8 parts of composite expanded graphite, 3-5 parts of phenolic resin, and 3-5 parts of chelating agent. The composite expanded graphite comprises a first expanded graphite and a second expanded graphite, and the flake sizes of the first expanded graphite and the second expanded graphite are different.

2. A ladle castable according to claim 1, characterized in that: The flake size of the first expanded graphite is 0.05 mm, and the flake size of the second expanded graphite is 0.07 mm.

3. A ladle castable according to claim 1, characterized in that: The mass ratio of the first expanded graphite to the second expanded graphite is 3:3-6.

4. A ladle castable according to claim 1, characterized in that: The fused corundum includes the following components in parts by weight: 12 to 15 parts of fused corundum with a particle size of 0 μm < particle size < 3 μm, 13 to 17 parts of fused corundum with a particle size of 3 μm ≤ particle size < 5 μm, 15 to 19 parts of fused corundum with a particle size of 5 μm ≤ particle size < 10 μm, 18 to 23 parts of fused corundum with a particle size of 10 μm ≤ particle size ≤ 25 μm, 6 to 9 parts of fused corundum with a particle size of 45 μm, and 8 to 12 parts of fused corundum with a particle size of 74 μm.

5. The ladle castable according to claim 1, characterized in that: The components of the ladle castable further include 2 to 5 parts of a composite catalyst, which is composed of ferrocene and nano iron powder.

6. A ladle castable according to claim 5, characterized in that: The particle size of the nano iron powder is 40-60 nm.

7. The ladle castable according to claim 5, characterized in that: The mass ratio of the ferrocene to the nano iron powder is 1-3:

3.

8. The ladle castable according to claim 1, characterized in that: The chelating agent is an organic carboxylic acid chelating agent, including one or more of citric acid, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid.

9. A method for preparing a ladle castable, for preparing the ladle castable according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mix the components uniformly to obtain a mixed aggregate; S2. After the mixed aggregate and water are evenly mixed, the mixture is placed in a mold and cast into shape. After demoulding and drying, the green body is sintered to obtain the ladle castable.

10. The method for preparing a ladle castable according to claim 9, characterized in that: During sintering in step S2, the green body is first heated to 400°C at a rate of 15°C / min, kept warm for 1 hour, then heated to 850-950°C at a rate of 10°C / min, kept warm for 2-4 hours, and the sintering atmosphere is nitrogen.

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