High-strength impact-resistant castable for steel ladle and preparation method of high-strength impact-resistant castable

Abstract

The high-strength impact-resistant castable comprises the following raw materials in percentage by weight: 80-90% of fused white corundum or tabular corundum or a mixture of the fused white corundum and the tabular corundum, 3-5% of fused magnesia powder, 2-5% of sintered spinel, 2-5% of spinel micro powder and 3-5% of activated alumina powder, the anti-explosion organic fiber accounts for 0.01-0.15% of the total weight of all the materials, and the silicon-zirconium sol composite binding agent accounts for 6-10% of the total weight of all the materials; the preparation method comprises the following steps: preparing a dry blend; preparing slurry; performing molding; and demolding and baking. According to the high-strength impact-resistant castable disclosed by the invention, the silicon-zirconium sol is adopted as a binding agent, so that the high-temperature breaking strength of the high-strength impact-resistant castable for the steel ladle at the temperature of not lower than 1400 DEG C is improved to be higher than 20MPa from the original not higher than 16MPa, the abrasion loss is reduced to be not higher than 0.5 g / h from the original not lower than 0.5 g / h, the strength retention rate is improved to be not lower than 90% from the original not higher than 88% after water cooling is performed for five times, and the service life of the high-strength impact-resistant castable for the steel ladle is prolonged. And the development requirements of steel ladles are completely met.

Description

Technical Field

[0001] This invention relates to a thermal insulation castable and its preparation method, specifically to a high-strength impact-resistant castable for steel ladles and its preparation method. Background Technology

[0002] As a container for holding steel, the ladle undertakes the task of transferring molten steel from the converter, refining, and continuous casting processes. The quality of the refractory lining inside the ladle directly affects its lifespan and the stable operation of production. The most economical and reasonable way to use a ladle is to match materials appropriately according to the different operating conditions of each part, so as to synchronize the lifespan of each part and reduce the frequency of minor and major repairs. Currently, the parts that limit the lifespan of the refractory lining in the ladle are mainly the slag line, the bottom impact zone, and functional materials such as permeable bricks and seat bricks. Among them, the bottom impact zone directly bears the impact of molten steel from the converter and is subject to large temperature fluctuations before and after the steel is heated, resulting in harsh operating conditions. Therefore, the refractory material in the bottom zone needs to have high room temperature strength, high-temperature strength, and good thermal shock resistance.

[0003] Currently, the bottom working layer of steel ladles generally uses alumina-magnesia-carbon bricks or spinel castables. Among them, alumina-magnesia-carbon bricks, due to their excellent erosion resistance, can achieve synchronous damage in the impact zone through vertical thickening design. Spinel castables, by introducing pre-synthesized spinel or generating spinel structures in situ, significantly improve slag penetration resistance. For example, Baosteel's 300-ton steel ladle uses corundum spinel castables, with a single service life of up to 55 heats. However, most steel ladle bottom castables currently use cement as a binder, which has defects such as high-temperature deterioration and volume deformation.

[0004] For example, the document published by China Patent Publication No. CN102617169A discloses "A corundum spinel castable and its preparation method". The document describes a process of first blending 1-10 wt% magnesium aluminum spinel fine powder, 5-10 wt% fused white corundum fine powder, 5-10 wt% α-Al2O3 micro powder, 2-8 wt% pure calcium aluminate cement, 0.06-0.2 wt% polycarboxylate superplasticizer, and 0.01-0.1 wt% organic fiber to prepare a pre-mixed powder. Then, 6-18 wt% partially stabilized zirconia particles or calcium zirconate particles, 45-70 wt% tabular corundum particles, and 1-10 wt% magnesium aluminum spinel particles are dry-mixed as aggregates for 4-6 minutes. The pre-mixed powder is then added and mixed for 15-30 minutes. Finally, 3-6 wt% water is added to the pre-mixed powder and aggregates, and the mixture is mixed for 3-5 minutes. The mixture is then vibrated, cast into molds, cured for 20-26 hours, demolded, and baked at 100-120℃ for 20-26 hours, then heated to 1450-1750℃ and held for 2-4 hours. The prepared corundum spinel castable exhibits good thermal shock stability, high high-temperature strength, high strength retention after thermal shock, and extended service life. However, this patent uses cement as a binder. At high temperatures, the CaO in the cement easily reacts with SiO2, Al2O3, and other aggregates to form low-melting-point phases (such as calcium silicates and calcium aluminates, with melting points mostly below 1300℃), leading to a decrease in the material's refractoriness and high-temperature strength. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the existing technology and provide a high-strength impact-resistant castable for steel ladles, which uses silicon zirconium sol as a binder, resulting in a high-temperature flexural strength of more than 20 MPa at a temperature of not less than 1400℃, an abrasion amount of no more than 0.5 g / h, and a strength retention rate of not less than 90% after 5 water cooling cycles, as well as a preparation method thereof.

[0006] Measures to achieve the above objectives: A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 80-90% fused white corundum (1mm < particle size ≤ 15mm), or tabular corundum with the same particle size as fused white corundum, or a mixture of both in any proportion; 3-5% fused magnesia powder (particle size ≤ 0.1mm); 2-5% sintered spinel (particle size < 1.0mm); 2-5% spinel microparticles (particle size ≤ 25μm); 3-5% activated alumina powder (particle size ≤ 0.1mm); plus, by weight percentage of the total weight of all the aforementioned materials: explosion-proof organic fiber (0.01-0.15%); and 6-10% silicon-zirconium sol-gel composite binder.

[0007] The silicon-zirconium sol composite binder is composed of tetraethyl orthosilicate, ethanol, deionized water, hydrochloric acid, zirconium oxychloride, nitric acid, and γ-aminopropyltriethoxysilane. It is prepared by a process of preparing a silicon sol precursor and a zirconium sol precursor, and then adding the silicon sol precursor and the zirconium sol precursor by dropwise addition. Its pH is 2.0 to 4.0. The solid content in the silicon-zirconium sol binder is 15% to 25%. The Si:Zr ratio is 1:1 to 3 or 1 to 3:1. Its color is a light blue emulsion.

[0008] The specific characteristics are as follows: the percentage of each particle size grade in the total weight of the added material is as follows: 8 < particle size ≤ 15 mm, or 5 < particle size ≤ 8 mm, or 3 < particle size ≤ 5 mm, or a mixture of both in any proportion, with each particle size grade accounting for 10-20% of the total weight of the material.

[0009] The key point is that the explosion-proof organic fiber refers to a composite of one or two of polypropylene fiber or polyethylene fiber.

[0010] A method for preparing a high-strength impact-resistant castable for steel ladles, comprising the following steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set amount of fused white fused alumina, or tabular fused alumina with the same particle size as fused white fused alumina, or a mixture of the two in any proportion, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, and added explosion-proof organic fiber into a forced mixer and dry mix for 1 to 3 minutes to form a dry mixture; 2) Preparation of slurry: Add the set amount of silicon-zirconium sol composite binder to the dry mixture at a rate of 0.1-0.5 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 105-115℃ and keep warm at this temperature for no less than 20 hours; when heat treatment is required, reheat to no less than 1400℃ and keep warm at this temperature for 2.5-3.5 hours.

[0011] The role and mechanism of each raw material and main process in this invention The reason for adding fused white corundum (1mm < particle size ≤ 15mm), or tabular corundum with the same particle size as fused white corundum, or a mixture of both in any proportion, to the castable in this invention is as follows: 8 < particle size ≤ 15mm: 10-20%; 5 < particle size ≤ 8mm: 5-20%; 3 < particle size ≤ 5mm: 5-20%; 1 < particle size ≤ 3mm: 10-20%; 0.1 < particle size ≤ 1mm: 5-20%; ≤ 0.01mm: 5-30%. This is because fused alumina has a dense structure, high hardness, excellent wear resistance and high temperature resistance (refractory ≥ 2000℃), and can provide a high-strength skeleton for the castable, resisting volume shrinkage and mechanical erosion at high temperatures. Tabular corundum: formed by Al2O3 sintering, with complete crystal development (tablet-shaped), high particle strength, low porosity and uniform distribution.

[0012] The reason for adding 3-5% fused magnesia powder with a particle size ≤0.1mm in this invention is as follows: First, it reacts with alumina to generate magnesium aluminum spinel in situ, which forms microcracks inside the castable, thereby improving the thermal shock resistance of the castable. However, too much spinel generated in situ will lead to an excessive number of microcracks, which will reduce the strength of the castable. Therefore, the amount of magnesia added must be controlled. Second, magnesia is added as a coagulant for zirconium silicate sol to accelerate the coagulation of zirconium silicate sol.

[0013] The reason for adding 2-5% sintered spinel with a particle size <1.0mm in this invention is that sintered spinel itself has excellent thermal shock resistance (low coefficient of thermal expansion) and slag resistance (it can react with iron slag and alkaline slag to form a high-viscosity protective layer, preventing slag penetration). As a secondary aggregate, it can further fill the gaps in the skeleton, and its granular structure can "disperse stress," alleviating thermal stress concentration at high temperatures, and improving the overall thermal shock resistance in conjunction with the main aggregate.

[0014] The reason for adding 2-5% spinel powder with a particle size ≤25μm in this invention is that spinel powder is an ultrafine dispersed phase with a large specific surface area and high activity. Its functions are: first, it can fill finer pores (smaller than the gaps between the main aggregate and fine powder), significantly reducing the porosity of the material and increasing its density; second, it easily undergoes a sintering reaction with the surrounding components at high temperatures, promoting the densification of the matrix (the cementing phase between aggregates) and enhancing the bonding strength between particles; and third, it can be uniformly dispersed in the matrix, which can "refine the grains" and further improve the uniformity of thermal shock resistance and slag erosion resistance.

[0015] The reason for adding 3-5% activated alumina powder with a particle size ≤0.1mm in this invention is threefold: First, it works synergistically with silica sol: the hydroxyl groups (-OH) on the surface of activated alumina can undergo a condensation reaction with the SiO2 sol particles of silica sol to form Si-O-Al chemical bonds, strengthening the gel network structure and improving the strength after dehydration at medium temperature (300-600℃). Second, it reacts with magnesia to form magnesium aluminum spinel in situ, creating microcracks inside the castable and thus improving the thermal shock resistance of the castable. Third, during high-temperature use or baking, the high reactivity of activated alumina allows it to undergo solid-phase reactions with other components in the castable (such as SiO2, mullite, etc.) to generate a high-performance high-temperature phase.

[0016] The reason why this invention uses explosion-proof organic fiber (0.01-0.15%) is that when baked at high temperature (300-500℃), the fiber will decompose and burn, leaving tiny air pores that can release the gas pressure inside the castable caused by water evaporation and mineral phase change, thus preventing the material from cracking (i.e., the "explosion-proof" effect) and ensuring the structural integrity after construction.

[0017] The reason why this invention uses a silicon-zirconium sol composite binder (6-10%) as an external binder, while controlling the solid content in the silicon-zirconium sol composite binder to be 15-25% and the Si:Zr ratio to be 1:1-3 or 1-3:1, is that the silicon-zirconium sol composite binder is a cementing nucleus composed of nano-sized SiO2 and ZrO2 colloidal particles. Firstly, at room temperature, the colloidal particles coagulate through surface tension, binding the aggregate and fine powder into a whole, providing the fluidity required for construction and the room temperature strength after hardening. Secondly, at high temperatures (above 800℃), SiO2 and ZrO2 react with components such as Al2O3 to form high-melting-point mullite (3Al2O3·2SiO2), zirconium aluminate, and other phases, strengthening the high-temperature bonding strength. At the same time, the high hardness of ZrO2 (Mohs hardness 8.5) combined with the flexibility of SiO2 significantly improves the surface wear resistance of the silicon-zirconium sol-bonded material, further enhancing the material's thermal shock resistance, improving overall strength, and ensuring structural stability under high-temperature conditions.

[0018] Compared with the prior art, this invention uses silicon-zirconium sol as a binder, which increases the high-temperature flexural strength of the high-strength impact-resistant castable for steel ladles from no more than 16MPa to more than 20MPa at a temperature of no less than 1400℃, reduces the wear rate from no less than 0.5g / h to no more than 0.5g / h, and increases the strength retention rate after 5 water cooling cycles from no more than 88% to no less than 90%, fully meeting the development requirements of steel ladles. Detailed Implementation

[0019] The present invention will now be described in detail: Example 1 A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 47% fused white corundum (1mm < particle size ≤ 15mm), wherein: 15% is fused white corundum of particle size 8 < ≤ 5mm; 15% is fused white corundum of particle size 5 < ≤ 8mm; 15% is fused white corundum of particle size 3 < ≤ 5mm; 20% is fused white corundum of particle size 1 < ≤ 3mm; 10% is fused white corundum of particle size 0.1 < ≤ 1mm; and 25% is fused white corundum of particle size ≤ 0.01mm. 43% tabular corundum (1mm < ≤ 15mm), wherein: 15% is fused white corundum of particle size 8 < ≤ 15mm; 15% is fused white corundum of particle size 5 < ≤ 8mm; and 3% is fused white corundum of particle size 3 < ≤ 15mm. < Particle size ≤ 5mm accounts for 15%; 1 < Particle size ≤ 3mm accounts for 20%; 0.1 < Particle size ≤ 1mm accounts for 10%; Particle size ≤ 0.01mm accounts for 25%; fused magnesia powder with particle size ≤ 0.1mm: 3%, sintered spinel with particle size < 1.0mm: 2%, spinel micro powder with particle size ≤ 25μm: 2%, activated alumina powder with particle size ≤ 0.1mm: 3%; plus the following percentages of the total weight of all the above materials: polypropylene fiber: 0.1%, silicon-zirconium sol composite binder: 6%, solid content in silicon-zirconium sol composite binder is 20%, silicon:zirconium is 1:1; Preparation steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set electric fused white alumina, tabular alumina, electric fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, and polypropylene fiber into a forced mixer and dry mix for 1.5 min to form a dry mixture. 2) Preparation of slurry: Add 6% silicon zirconium sol composite binder to the dry mixture at a rate of 0.2 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 108℃ and keep warm at this temperature for 23 hours; then heat-treat by heating to 1410℃ and keeping warm at this temperature for 3 hours.

[0020] The test results showed that the high-temperature flexural strength of this embodiment was 20.5 MPa, the wear rate was 0.45 g / h, and the strength retention rate was 92% after 5 water cooling cycles.

[0021] Example 2 A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 1mm < particle size ≤ 15mm fused white corundum: 81%, of which particle size 8 < particle size ≤ 15mm accounts for 10%; 5 < particle size ≤ 8mm accounts for 15%; 3 < particle size ≤ 5mm accounts for 15%; 1 < particle size ≤ 3mm accounts for 20%; 0.1 < particle size ≤ 1mm accounts for 20%; particle size ≤ 0.01mm accounts for 20%; fused magnesia powder with particle size ≤ 0.1mm: 5%; sintered spinel with particle size < 1.0mm: 5%; spinel micro powder with particle size ≤ 25μm: 5%; activated alumina powder with particle size ≤ 0.1mm: 4%; plus the following weight percentage of all the aforementioned materials: polyethylene fiber: 0.09%; silicon-zirconium sol binder: 8%; the solid content of the silicon-zirconium sol composite binder is 15%, and the silicon:zirconium ratio is 1:2.

[0022] Preparation steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set amount of fused white corundum, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder and polyethylene fiber into a forced mixer and dry mix for 1 minute to form a dry mixture. 2) Preparation of slurry: Add 8% silicon zirconium sol composite binder to the dry mixture at a rate of 0.3 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 105℃ and keep warm at this temperature for 20.5 hours; then heat-treat by heating to 1430℃ and keeping warm at this temperature for 3.1 hours.

[0023] The test results showed that the high-temperature flexural strength of this embodiment was 21.8 MPa, the wear rate was 0.48 g / h, and the strength retention rate was 90% after 5 water cooling cycles.

[0024] Example 3 A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 85% tabular corundum (1mm < particle size ≤ 15mm), of which 15% is composed of particle size 8 < particle size ≤ 15mm; 10% is composed of particle size 5 < particle size ≤ 8mm; 10% is composed of particle size 3 < particle size ≤ 5mm; 20% is composed of particle size 1 < particle size ≤ 3mm; 15% is composed of particle size 0.1 < particle size ≤ 1mm; 30% is composed of particle size ≤ 0.01mm; 4% is fused magnesia powder with particle size ≤ 0.1mm; 3% is sintered spinel with particle size < 1.0mm; 4% is spinel micro powder with particle size ≤ 25μm; 4% is activated alumina powder with particle size ≤ 0.1mm; plus 0.1% of the total weight percentage of all the aforementioned materials, a mixture of polypropylene fiber and polyethylene fiber in any proportion; and 7% is silicon-zirconium sol composite binder, wherein the solid content of the silicon-zirconium sol composite binder is 25%, and the silicon:zirconium ratio is 1:3.

[0025] Preparation steps: 1) Preparation of dry mixture: According to the particle size distribution, first mix the set amount of tabular corundum, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, polypropylene fiber and polyethylene fiber mixture, pour the mixture into a forced mixer, and dry mix for 2 minutes to form a dry mixture. 2) Preparation of slurry: Add 7% silicon zirconium sol composite binder to the dry mixture at a rate of 0.35 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 112℃ and keep warm at this temperature for 24 hours; then heat-treat by heating to 1420℃ and keeping warm at this temperature for 3.2 hours.

[0026] The test results showed that the high-temperature flexural strength of this embodiment was 20.2 MPa, the wear rate was 0.43 g / h, and the strength retention rate was 93% after 5 water cooling cycles.

[0027] Example 4 A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 45% fused white corundum (1mm < particle size ≤ 15mm), of which 15% is fused white corundum of particle size 8 < ≤ 15mm; 15% is fused white corundum of particle size 5 < ≤ 8mm; 15% is fused white corundum of particle size 3 < ≤ 5mm; 20% is fused white corundum of particle size 1 < 3mm; 10% is fused white corundum of particle size 0.1 < ≤ 1mm; 25% is fused white corundum of particle size ≤ 0.01mm; and 40% is tabular corundum (1mm < ≤ 15mm), of which 15% is fused white corundum of particle size 8 < ≤ 15mm; 15% is fused white corundum of particle size 5 < ≤ 8mm; 15% is fused white corundum of particle size 3 < ≤ 5mm; 20% is fused white corundum of particle size 1 < 3mm; 10% is fused white corundum of particle size 0.1 < ≤ 1mm; and 25% is fused white corundum of particle size ≤ 0.01mm. Particle size ≤ 5mm accounts for 15%; 1 < particle size ≤ 3mm accounts for 20%; 0.1 < particle size ≤ 1mm accounts for 10%; particle size ≤ 0.01mm accounts for 25%; fused magnesia powder with particle size ≤ 0.1mm: 3%, sintered spinel with particle size < 1.0mm: 4%, spinel micro powder with particle size ≤ 25μm: 3%, activated alumina powder with particle size ≤ 0.1mm: 5%; plus the following percentages of the total weight of all the above materials: polypropylene fiber: 0.15%, silicon-zirconium sol composite binder: 7%, the solid content of the silicon-zirconium sol composite binder is 25%, and the silicon:zirconium ratio is 2:1.

[0028] Preparation steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set amount of fused white corundum, tabular corundum, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, and polypropylene fiber into a forced mixer and dry mix for 2.5 minutes to form a dry mixture. 2) Preparation of slurry: Add 7% silicon zirconium sol composite binder to the dry mixture at a rate of 0.4 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 115℃ and keep warm at this temperature for 24 hours; then heat-treat by heating to 1480℃ and keeping warm at this temperature for 2.5 hours.

[0029] The test results showed that the high-temperature flexural strength of this embodiment was 21.3 MPa, the wear rate was 0.4 g / h, and the strength retention rate was 92% after 5 water cooling cycles.

[0030] Example 5 A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 1mm < particle size ≤ 15mm electrofused white corundum: 30%, of which particle size 8 < particle size ≤ 15mm accounts for 15%; 5 < particle size ≤ 8mm accounts for 10%; 3 < particle size ≤ 5mm accounts for 10%; 1 < particle size ≤ 3mm accounts for 20%; 0.1 < particle size ≤ 1mm accounts for 15%; particle size ≤ 0.01mm accounts for 30%; 1mm < particle size ≤ 15mm tabular corundum: 50%, of which particle size 8 < particle size ≤ 15mm accounts for 15%; 5 < particle size ≤ 8mm accounts for 10%; 3 ... accounts for 50%. Particle size ≤ 5mm accounts for 10%; 1 < particle size ≤ 3mm accounts for 20%; 0.1 < particle size ≤ 1mm accounts for 15%; particle size ≤ 0.01mm accounts for 30%; fused magnesia powder with particle size ≤ 0.1mm: 5%, sintered spinel with particle size < 1.0mm: 5%, spinel micro powder with particle size ≤ 25μm: 5%, activated alumina powder with particle size ≤ 0.1mm: 5%; plus the following percentages of the total weight of all the above materials: polypropylene fiber: 0.1%, silicon-zirconium sol composite binder: 8%, the solid content of the silicon-zirconium sol composite binder is 20%, and the silicon:zirconium ratio is 2:1.

[0031] Preparation steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set amount of fused white corundum, tabular corundum, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, and polypropylene fiber into a forced mixer and dry mix for 3 minutes to form a dry mixture. 2) Preparation of slurry: Add 8% silicon zirconium sol composite binder to the dry mixture at a rate of 0.5 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 113℃ and keep warm at this temperature for 24.5 hours; then heat-treat by heating to 1450℃ and keeping warm at this temperature for 2.5 hours.

[0032] The test results showed that the high-temperature flexural strength of this embodiment was 20.7 MPa, the wear rate was 0.4 g / h, and the strength retention rate was 92% after 5 water cooling cycles.

[0033] Example 6 A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 55% fused white corundum (1mm < particle size ≤ 15mm), of which 10% is fused white corundum of particle size 8 < ≤ 15mm; 10% is fused white corundum of particle size 5 < ≤ 8mm; 15% is fused white corundum of particle size 3 < ≤ 5mm; 15% is fused white corundum of particle size 1 < 3mm; 20% is fused white corundum of particle size 0.1 < ≤ 1mm; 30% is fused white corundum of particle size ≤ 0.01mm; and 30% is fused white corundum of particle size 1mm < ≤ 15mm. 15% of the particles are ≤5mm; 15% are ≤3mm; 20% are ≤1mm; 30% are ≤0.01mm; 4% are fused magnesia powder with a particle size ≤0.1mm; 3% are sintered spinel with a particle size <1.0mm; 4% are spinel micro powder with a particle size ≤25μm; 4% are activated alumina powder with a particle size ≤0.1mm; plus the following percentages of the total weight of all the above materials: polypropylene fiber: 0.15%; silicon-zirconium sol composite binder: 10%; the solid content of the silicon-zirconium sol composite binder is 22%; the silicon:zirconium ratio is 3:1.

[0034] Preparation steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set amount of fused white corundum, tabular corundum, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, and polypropylene fiber into a forced mixer and dry mix for 2 minutes to form a dry mixture. 2) Preparation of slurry: Add 10% of the silicon zirconium sol to the dry mixture at a rate of 0.3 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 110℃ and keep at this temperature for 24 hours; then heat-treat by heating to 1440℃ and keeping at this temperature for 2.5 hours. The test results showed that the high-temperature flexural strength of this embodiment was 21.2 MPa, the wear rate was 0.43 g / h, and the strength retention rate was 92% after 5 water cooling cycles.

[0035] This specific embodiment is merely a best example and is not intended to limit the implementation of the technical solution of the present invention.

Claims

1. A high-strength impact-resistant castable for steel ladles, comprising the following raw material composition and weight percentage: 80-90% of fused white corundum (1mm < particle size ≤ 15mm), or tabular corundum with the same particle size as fused white corundum, or a mixture of both in any proportion; 3-5% of fused magnesia powder (particle size ≤ 0.1mm); 2-5% of sintered spinel (particle size < 1.0mm); 2-5% of spinel microparticles (particle size ≤ 25μm); 3-5% of activated alumina powder (particle size ≤ 0.1mm); plus the following: explosion-proof organic fiber (0.01-0.15%) and silicon-zirconium sol-gel composite binder (6-10%).

2. The high-strength impact-resistant castable for steel ladles as described in claim 1, characterized in that: The silicon-zirconium sol composite binder is composed of tetraethyl orthosilicate, ethanol, deionized water, hydrochloric acid, zirconium oxychloride, nitric acid, and γ-aminopropyltriethoxysilane. It is prepared through processes including the preparation of a silica sol precursor and a zirconium sol precursor, followed by dropwise addition of the silica sol precursor and the zirconium sol precursor. Its pH is between 2.0 and 4.0; the solid content in the silicon-zirconium sol binder is 15% to 25%; the Si:Zr ratio is 1:1 to 3 or 1 to 3:1; and its color is a pale blue emulsion.

3. The high-strength impact-resistant castable for steel ladles as described in claim 1, characterized in that: The fused white corundum with a particle size of 1mm < ≤ 15mm, or tabular corundum with the same particle size as fused white corundum, or a mixture of both in any proportion, shall have the following percentages of each particle size class in the total weight of the added material: 8 < ≤ 15mm, 10-20%; 5 < ≤ 8mm, 5-20%; 3 < ≤ 5mm, 5-20%; 1 < ≤ 3mm, 10-20%; 0.1 < ≤ 1mm, 5-20%; and ≤ 0.01mm, 5-30%.

4. The high-strength impact-resistant castable for steel ladles as described in claim 1, characterized in that: The explosion-proof organic fiber refers to a composite of one or two of polypropylene fiber or polyethylene fiber.

5. A method for preparing a high-strength impact-resistant castable for steel ladles as described in claim 1, comprising the following steps: 1) Preparation of dry mixture: According to the particle size distribution, first put the set amount of fused white fused alumina, or tabular fused alumina with the same particle size as fused white fused alumina, or a mixture of the two in any proportion, fused magnesia powder, activated alumina, sintered spinel, spinel micro powder, and explosion-proof organic fiber into a forced mixer and dry mix for 1 to 3 minutes to form a dry mixture; 2) Preparation of slurry: Add the set amount of silicon-zirconium sol composite binder to the dry mixture at a rate of 0.1-0.5 kg / min, and then stir until the slurry is uniform; 3) Place the slurry into a mold pre-coated with a release agent and vibrate to remove air bubbles until it is compacted; 4) After demolding, bake at 105-115℃ and keep warm at this temperature for no less than 20 hours; when heat treatment is required, reheat to no less than 1400℃ and keep warm at this temperature for 2.5-3.5 hours.