A tundish covering castable with high thermal shock resistance and slag resistance and a preparation method and application thereof

Abstract

The application provides a tundish cover casting material with high thermal shock resistance and high slag erosion resistance, a preparation method and application thereof, and belongs to the technical field of tundish cover casting materials. The tundish cover casting material with high thermal shock resistance and high slag erosion resistance comprises the following raw materials in preparation: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, alpha-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water. The results of the examples show that the tundish cover casting material with high thermal shock resistance and high slag erosion resistance provided by the application has an apparent porosity of 10-15%, a bulk density of 2.6-3.0 g / cm 3 , and a service life of 250-300 times.

Description

Technical Field

[0001] This invention relates to the field of tundish cover casting technology, and in particular to a tundish cover casting material with high resistance to thermal shock and slag erosion, its preparation method, and its application. Background Technology

[0002] The tundish is one of the key pieces of equipment in continuous casting steelmaking. Its main functions are to further purify the tundish, stabilize the temperature, fine-tune the alloy composition, further refine the metallurgical slag, and ensure the stable and smooth operation of the continuous casting process. In recent years, with the enhancement of the metallurgical functions of the tundish and the demand for energy conservation and emission reduction, the role of the tundish cover has become increasingly prominent, and its service performance directly affects the output and quality of continuously cast steel. The tundish cover is an important component of the tundish, mainly providing an environment for heat preservation and preventing molten steel splashing. Therefore, the refractory material of the tundish cover faces multiple pressures: on the one hand, the working environment is relatively harsh, frequently subjected to thermomechanical vibration and impact; on the other hand, during baking, the working surface of the tundish is subjected to the scorching of high-temperature flames and the scouring of high-temperature airflow, while the working surface of the cover is also subject to erosion by splashed molten slag. Currently, most refractory materials used for tundish covers are high-alumina and mullite-based, employing calcium aluminate cement as a binder. The high thermal conductivity of dense corundum particles leads to an increased thermal conductivity in the final product, resulting in greater heat loss and hindering stable steelmaking. Furthermore, the slag erosion resistance of purely aluminosilicate refractories needs further improvement. Therefore, there is an urgent need to develop a high-performance tundish cover castable to meet low-carbon requirements and increasingly demanding operating conditions.

[0003] Mullite is a stable binary solid solution in the Al2O3-SiO2 system under normal pressure, characterized by a high melting point, low coefficient of expansion, and excellent thermal shock resistance and corrosion resistance. As an important refractory material, it has been successfully applied to furnace linings in high-temperature industries, with service temperatures mainly concentrated in the range of 1200–1500℃. In fact, Cr2O3 is recognized as one of the best refractory materials in terms of slag erosion resistance, and it is widely used in key high-temperature industries such as non-ferrous metallurgy, cement, and petrochemicals. Similarly, chromium oxide-containing materials have been developed in castable systems, significantly improving their resistance to slag erosion and penetration. Therefore, the preparation of an aluminosilicate intermediate ladle cover castable containing Cr2O3 is of significant practical importance for improving thermal shock stability and erosion resistance.

[0004] Patent "CN107759212A" uses mullite particles, corundum particles, fine corundum powder, α-Al2O3, and SiO2 micro powder as raw materials to prepare mullite castables for tundish covers. This significantly improves performance compared to traditional tundish cover castables using bauxite as aggregate, exhibiting good thermal shock resistance. Patent "CN110668830A" uses sintered mullite and calcined bauxite as raw materials. By controlling the ratio of Al2O3 and SiO2 in the matrix, it ensures that the matrix mineral phase composition falls within the region where the mullite and corundum phases coexist, resulting in castables with good thermal shock resistance and high strength at medium and high temperatures. However, the mullite castables prepared by the above two patents do not consider the material's high-temperature erosion resistance and cannot meet the requirements for tundish cover materials to resist slag penetration. Patent "CN116874290A" prepares a chromium corundum castable containing calcium hexaaluminate, which features good thermal shock resistance, good high-temperature erosion resistance, and long service life. Patent "CN111439993A" utilizes corundum as aggregate and adds Cr2O3 to improve the material's erosion resistance, further enhancing its resistance to slag erosion and permeability. In summary, it is feasible to improve the slag erosion resistance of mullite castables by introducing Cr2O3 into tundish cover castables. However, the thermal shock resistance and slag erosion resistance of the tundish cover castable obtained by the above method still do not meet the technical requirements.

[0005] Therefore, how to further improve the slag erosion resistance of the intermediate ladle cover castable has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a tundish cover castable with high thermal shock resistance and high slag erosion resistance, its preparation method and application. The tundish cover castable provided by this invention has high strength, high thermal shock resistance and excellent slag erosion resistance.

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

[0008] This invention provides a tundish cover castable with high thermal shock resistance and high slag erosion resistance. The raw materials for preparing the tundish cover castable include: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water.

[0009] Based on a total mass ratio of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement of 100%, the composition is as follows: 65-75% Al2O3-SiO2-Cr2O3 particles, 10-13% Al2O3-SiO2-Cr2O3 fine powder, 5-8% α-Al2O3 micro powder, 6-10% SiO2 micro powder, and 3-6% calcium aluminate cement.

[0010] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0011] 1) Mix 66-74 wt% Al2O3, 20-26 wt% SiO2 micro powder and 4-8 wt% Cr2O3 and then ball mill to obtain a premixed powder;

[0012] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres;

[0013] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles.

[0014] Preferably, the Al2O3-SiO2-Cr2O3 particles are graded as follows: 40-50 wt% of 3-5 mm Al2O3-SiO2-Cr2O3 particles, 25-40 wt% of 1-3 mm Al2O3-SiO2-Cr2O3 particles, and 10-25 wt% of 0.1-1 mm Al2O3-SiO2-Cr2O3 particles.

[0015] Preferably, the Al2O3-SiO2-Cr2O3 particles contain 62-76 wt% mullite, 4-8 wt% Cr2O3, and the remaining components.

[0016] Preferably, the particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm.

[0017] Preferably, the particle size of the α-Al2O3 micro powder is ≤5μm, and the particle size of the SiO2 micro powder is ≤2μm.

[0018] Preferably, the calcium aluminate cement has a particle size of 325 mesh, and the pure calcium aluminate cement contains ≥71wt% Al2O3.

[0019] Preferably, the amount of water-reducing agent is 0.1 to 0.2% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder and calcium aluminate cement.

[0020] Preferably, the amount of water used is 4.5 to 6.8% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0021] This invention provides a method for preparing the tundish cover castable with high thermal shock resistance and high slag erosion resistance described in the above technical solution, comprising the following steps:

[0022] (1) Mix Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement and water-reducing agent, and then add water to mix to obtain a mixture;

[0023] (2) The mixture obtained in step (1) is successively molded, cured, demolded and baked to obtain intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance.

[0024] The present invention provides the application of the tundish cover castable with high thermal shock resistance and high slag erosion resistance described in the above technical solution or the tundish cover castable with high thermal shock resistance and high slag erosion resistance prepared by the preparation method described in the above technical solution in steelmaking.

[0025] This invention provides a tundish cover castable with high resistance to thermal shock and slag erosion. The raw materials for preparing the tundish cover castable include: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water-reducing agent, and water; based on a total mass ratio of 100% for Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement, the composition is: 65-75% Al2O3-SiO2-Cr2O3 particles, 10-13% Al2O3-SiO2 micro powder, and 10-13% Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement. The Al2O3-SiO2-Cr2O3 particles are prepared by mixing 66-74 wt% Al2O3, 20-26 wt% SiO2 powder and 4-8 wt% Cr2O3 and then ball milling to obtain a premixed powder; 2) adding water to the premixed powder obtained in step 1), and then mixing, rotary granulating and drying in sequence to obtain pre-formed spheres; 3) calcining and crushing the pre-formed spheres obtained in step 2) in sequence to obtain Al2O3-SiO2-Cr2O3 particles.This invention introduces SiO2 micropowder into Al2O3. The SiO2 micropowder fills the voids between Al2O3 particles and reacts in situ with Al2O3 to form mullite, resulting in Al2O3-SiO2-Cr2O3 particles containing the mullite phase. By introducing Cr2O3 into the particles, its excellent chemical stability and absorption of oxides in slag ensure the superior slag erosion resistance of the Al2O3-SiO2-Cr2O3 particles. Simultaneously, the formation of a solid solution between Cr2O3, Al2O3, and SiO2 at high temperatures enhances the stability of trivalent chromium, avoiding hexavalent chromium contamination. This allows for the preparation of chromium oxide particles with hexavalent chromium content far below the usage limits. The introduced Cr2O3 is uniformly distributed around the mullite, inhibiting excessive growth of needle-like or columnar mullite, thus improving mechanical properties and further enhancing the slag erosion resistance of the Al2O3-SiO2-Cr2O3 particles. The mullite structure in Al2O3-SiO2-Cr2O3 particles exhibits needle-like or short columnar crystals, forming a cross-linked network structure. This gives the tundish cap castable high structural strength and improves its thermal shock resistance. Simultaneously, the residual Al2O3 in the Al2O3-SiO2-Cr2O3 particles and the SiO2 micropowder in the matrix can regenerate in-situ mullite at the interface under high temperatures, further enhancing the bonding between the matrix and aggregate. This creates a synergistic effect between the aggregate, matrix, and interface, further strengthening the interfacial bonding and resulting in a more uniform phase distribution in the mullite castable, thus improving its thermal shock resistance and slag penetration resistance. When the Al2O3-SiO2-Cr2O3 particles are slightly rich in silica, the alumina in the matrix also forms a mullite reinforcing phase at the interface, resulting in high strength, high thermal shock resistance, and excellent slag erosion resistance in the prepared tundish cap castable. The results of the embodiments show that the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance provided by the present invention has an apparent porosity of 10-15% and a bulk density of 2.6-3.0 g / cm³. 3 The service life reaches 250-300 cycles; when the tundish cover castable is kept at 110℃ for 24 hours, the room temperature flexural strength of the tundish cover castable is 10-18MPa; when the tundish cover castable is kept at 1600℃ for 3 hours, the room temperature flexural strength is 20-32MPa; when the tundish cover castable is kept at 1600℃ for 3 hours and then subjected to slag erosion test, there is no obvious penetration and erosion. Attached Figure Description

[0026] Figure 1 The microstructure of the intermediate ladle cap castable prepared in Example 1 of the present invention is shown. Detailed Implementation

[0027] This invention provides a tundish cover castable with high thermal shock resistance and high slag erosion resistance. The raw materials for preparing the tundish cover castable include: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water.

[0028] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art.

[0029] In this invention, the preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0030] 1) Mix 66-74 wt% Al2O3, 20-26 wt% SiO2 micro powder and 4-8 wt% Cr2O3 and then ball mill to obtain a premixed powder;

[0031] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres;

[0032] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles.

[0033] In this invention, 66-74 wt% Al2O3, 20-26 wt% SiO2 micro powder and 4-8 wt% Cr2O3 are mixed and then ball-milled to obtain a premixed powder.

[0034] In this invention, the Al2O3 is preferably industrial Al2O3; the Al2O3 content in the industrial Al2O3 is preferably ≥97wt%; the particle size of the Al2O3 is preferably ≤8μm; the particle size of the SiO2 micro powder is preferably ≤2μm; and the particle size of the Cr2O3 is preferably ≤5μm. This invention uses industrial Al2O3 as a raw material, which can reduce the impurity content and further improve the various properties of the castable.

[0035] In this invention, the ball milling is preferably performed in a planetary ball mill. This invention does not impose any specific limitation on the model of the planetary ball mill; any commercially available product well-known to those skilled in the art can be used.

[0036] In this invention, the ball milling speed is preferably 200–500 r / min, more preferably 300 r / min; the ball milling time is preferably 4–8 h, more preferably 5–7 h, and even more preferably 6–7 h. By controlling the ball milling speed and time, this invention ensures that the raw materials in the premixed powder are mixed evenly.

[0037] After obtaining the premixed powder, the present invention adds water to the premixed powder, and then mixes, rotates and granulates and dries in sequence to obtain preformed spheres.

[0038] In this invention, the amount of water used is preferably 6-10 wt% of the premixed powder. By controlling the amount of water added, this invention can ensure better granulation.

[0039] The present invention does not impose any special limitation on the mixing method, as long as the premixed powder and water are completely mixed.

[0040] The present invention does not have any special limitations on the specific operation of the rotary granulation, as long as it can obtain pre-formed spheres with the required particle size.

[0041] In this invention, the drying temperature is preferably 100–120°C, more preferably 110°C; the drying time is preferably 24 hours. This invention removes moisture through drying, facilitating subsequent calcination.

[0042] In this invention, the particle size of the preformed spheres is preferably 15-25 mm, more preferably 20 mm.

[0043] After obtaining the preformed spheres, the present invention sequentially calcines and crushes the preformed spheres to obtain Al2O3-SiO2-Cr2O3 particles.

[0044] In this invention, the calcination temperature is preferably 1500-1600℃, more preferably 1550-1600℃; the calcination time is preferably 3-8h, more preferably 4-7h, and even more preferably 5-6h.

[0045] This invention does not impose any specific limitations on the crushing operation, as long as the particle size distribution of Al2O3-SiO2-Cr2O3 meets the requirements. In this invention, the preferred particle size distribution of the Al2O3-SiO2-Cr2O3 particles is: 40-50 wt% Al2O3-SiO2-Cr2O3 particles of 3-5 mm, 25-40 wt% Al2O3-SiO2-Cr2O3 particles of 1-3 mm, and 10-25 wt% Al2O3-SiO2-Cr2O3 particles of 0.1-1 mm.

[0046] In this invention, the Al2O3-SiO2-Cr2O3 particles preferably contain 62-76 wt% mullite, 4-8 wt% Cr2O3, and the remaining other components.

[0047] Based on a total mass ratio of 100% for Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement, the composition is: 65-75% Al2O3-SiO2-Cr2O3 particles, 10-13% Al2O3-SiO2-Cr2O3 fine powder, 5-8% α-Al2O3 micro powder, 6-10% SiO2 micro powder, and 3-6% calcium aluminate cement.

[0048] In this invention, the particle size of the Al2O3-SiO2-Cr2O3 fine powder is preferably ≤0.088mm. This invention does not impose any special limitations on the specific composition and preparation process of the Al2O3-SiO2-Cr2O3 fine powder; the composition and preparation process are the same as those of the aforementioned Al2O3-SiO2-Cr2O3 particles.

[0049] In this invention, the particle size of the α-Al2O3 micro powder is preferably ≤5μm; the particle size of the SiO2 micro powder is preferably ≤2μm; the particle size of the calcium aluminate cement is preferably 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is preferably ≥71wt%.

[0050] In this invention, the water-reducing agent is preferably a polycarboxylate water-reducing agent; the amount of the water-reducing agent is 0.1 to 0.2% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder and calcium aluminate cement.

[0051] In this invention, the amount of water used is 4.5 to 6.8% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement and water-reducing agent, more preferably 6.0 to 6.5%.

[0052] This invention introduces SiO2 micropowder into Al2O3. The SiO2 micropowder fills the voids between Al2O3 particles and reacts in situ with Al2O3 to form mullite, resulting in Al2O3-SiO2-Cr2O3 particles containing the mullite phase. By introducing Cr2O3 into the particles, its excellent chemical stability and absorption of oxides in slag ensure the superior slag erosion resistance of the Al2O3-SiO2-Cr2O3 particles. Simultaneously, the formation of a solid solution between Cr2O3, Al2O3, and SiO2 at high temperatures enhances the stability of trivalent chromium, avoiding hexavalent chromium contamination. This allows for the preparation of chromium oxide particles with hexavalent chromium content far below the usage limits. The introduced Cr2O3 is uniformly distributed around the mullite, inhibiting excessive growth of needle-like or columnar mullite, thus improving mechanical properties and further enhancing the slag erosion resistance of the Al2O3-SiO2-Cr2O3 particles. The mullite structure in Al2O3-SiO2-Cr2O3 particles exhibits needle-like or short columnar crystals, forming a cross-linked network structure. This gives the tundish cap castable high structural strength and improves its thermal shock resistance. Simultaneously, the residual Al2O3 in the Al2O3-SiO2-Cr2O3 particles and the SiO2 micropowder in the matrix can regenerate in-situ mullite at the interface under high temperatures, further enhancing the bonding between the matrix and aggregate. This creates a synergistic effect between the aggregate, matrix, and interface, further strengthening the interfacial bonding and resulting in a more uniform phase distribution in the mullite castable, thus improving its thermal shock resistance and slag penetration resistance. When the Al2O3-SiO2-Cr2O3 particles are slightly rich in silica, the alumina in the matrix also forms a mullite reinforcing phase at the interface, resulting in high strength, high thermal shock resistance, and excellent slag erosion resistance in the prepared tundish cap castable.

[0053] This invention provides a method for preparing the tundish cover castable with high thermal shock resistance and high slag erosion resistance described in the above technical solution, comprising the following steps:

[0054] (1) Mix Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement and water-reducing agent, and then add water to mix to obtain a mixture;

[0055] (2) The mixture obtained in step (1) is successively molded, cured, demolded and baked to obtain intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance.

[0056] This invention involves mixing Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and a water-reducing agent, then adding water to obtain a mixture. This invention does not impose any particular limitation on the mixing method, as long as it ensures that all components are mixed uniformly.

[0057] After obtaining the mixture, the present invention sequentially molds, cures, demolds and bakes the mixture to obtain an intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance.

[0058] The present invention does not have any special limitation on the specific molding method, as long as the shape and size of the intermediate ladle cap casting material meet the requirements.

[0059] In this invention, the curing temperature is preferably room temperature, more preferably 25°C; the curing humidity is preferably 70-80%RH, more preferably 75%RH; and the curing time is preferably 24 hours.

[0060] The present invention does not have any special limitation on the specific demolding method, as long as it can separate the intermediate bag cover casting material from the mold.

[0061] In this invention, the baking temperature is preferably 1500–1600°C; the baking time is preferably 2–4 hours, more preferably 3 hours. By controlling the baking parameters, this invention can further improve the density of the intermediate ladle cover castable, thereby improving its mechanical properties and erosion resistance.

[0062] The preparation process provided by this invention is simple, and the prepared tundish cover castable has the characteristics of high strength, good thermal shock stability and excellent erosion resistance, which can meet the stringent requirements of tundish cover service life and slag erosion resistance.

[0063] The present invention also provides the application of the tundish cover castable with high thermal shock resistance and high slag erosion resistance described in the above technical solution or the tundish cover castable with high thermal shock resistance and high slag erosion resistance prepared by the preparation method described in the above technical solution in steelmaking.

[0064] The present invention does not impose any special limitation on the specific application method, and any application method known to those skilled in the art can be used.

[0065] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0066] Example 1

[0067] A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water;

[0068] Based on a total mass ratio of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement of 100%, the composition is: 75% Al2O3-SiO2-Cr2O3 particles, 10% Al2O3-SiO2-Cr2O3 fine powder, 5% α-Al2O3 micro powder, 6% SiO2 micro powder, and 4% calcium aluminate cement.

[0069] The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; the particle size of the α-Al2O3 micro powder is ≤5μm; the particle size of the SiO2 micro powder is ≤2μm; the particle size of the calcium aluminate cement is 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is ≥71wt%.

[0070] The water-reducing agent is a polycarboxylate-based water-reducing agent; the dosage of the water-reducing agent is 0.1% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement; the dosage of water is 5% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0071] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0072] 1) 74 wt% Al2O3, 20 wt% SiO2 micro powder and 6 wt% Cr2O3 were mixed and ball-milled in a planetary ball mill to obtain a premixed powder; the ball milling speed was 300 r / min; the ball milling time was 6 h; the Al2O3 was industrial Al2O3; the Al2O3 content of the industrial Al2O3 was ≥97 wt%; the particle size of the Al2O3 was ≤8 μm, the particle size of the SiO2 micro powder was ≤2 μm, and the particle size of the Cr2O3 was ≤5 μm;

[0073] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; the amount of water used is 8 wt% of the premixed powder; the drying temperature is 110℃ and the drying time is 24h; the particle size of the pre-made spheres is 20mm.

[0074] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1500℃ and the calcination time is 5h.

[0075] The Al2O3-SiO2-Cr2O3 particles are graded as follows: 45wt% of 3-5mm Al2O3-SiO2-Cr2O3 particles, 30wt% of 1-3mm Al2O3-SiO2-Cr2O3 particles, and 25wt% of 0.1-1mm Al2O3-SiO2-Cr2O3 particles; the Al2O3-SiO2-Cr2O3 particles contain 66-74wt% mullite and 6-8wt% Cr2O3.

[0076] The preparation method of the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance includes the following steps:

[0077] (1) First, mix Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement and water-reducing agent, then add water and mix evenly to obtain a mixture;

[0078] (2) The mixture obtained in step (1) is sequentially molded, cured, demolded and baked to obtain intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance; the curing temperature is 25℃; the curing humidity is 75%RH; the curing time is 1 day; the baking temperature is 1500℃; the baking time is 3h.

[0079] The microstructure of the intermediate ladle cap castable prepared in Example 1 was observed using a field emission scanning electron microscope (FE-SEM, Nova 400 NanoSEM, FEI Company, USA). The results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the introduced Cr2O3 is uniformly distributed around the mullite, and the mullite structure in the Al2O3-SiO2-Cr2O3 particles exhibits needle-like or short columnar crystals, forming a cross-linked network structure.

[0080] The performance of the tundish cover castable prepared in Example 1 was tested. When the tundish cover castable was kept at 110℃ for 24 hours, the room temperature flexural strength was 12.7 MPa. When the tundish cover castable was kept at 1500℃ for 3 hours, the room temperature flexural strength was 31.5 MPa. After keeping the tundish cover castable at 1500℃ for 3 hours, a slag erosion test was conducted, and no obvious penetration or erosion was observed.

[0081] Example 2

[0082] A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water;

[0083] Based on a total mass ratio of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement of 100%, the composition is: 71% Al2O3-SiO2-Cr2O3 particles, 12% Al2O3-SiO2-Cr2O3 fine powder, 6% α-Al2O3 micro powder, 7% SiO2 micro powder, and 4% calcium aluminate cement.

[0084] The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; the particle size of the α-Al2O3 micro powder is ≤5μm; the particle size of the SiO2 micro powder is ≤2μm; the particle size of the calcium aluminate cement is 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is ≥71wt%.

[0085] The water-reducing agent is a polycarboxylate-based water-reducing agent; the dosage of the water-reducing agent is 0.1% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement; the dosage of water is 5% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0086] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0087] 1) 69 wt% Al2O3, 24 wt% SiO2 micro powder and 7 wt% Cr2O3 were mixed and ball-milled in a planetary ball mill to obtain a premixed powder; the ball milling speed was 300 r / min; the ball milling time was 6 h; the Al2O3 was industrial Al2O3; the Al2O3 content of the industrial Al2O3 was ≥97 wt%; the particle size of the Al2O3 was ≤8 μm, the particle size of the SiO2 micro powder was ≤2 μm, and the particle size of the Cr2O3 was ≤5 μm;

[0088] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; the amount of water used is 8 wt% of the premixed powder; the drying temperature is 110℃ and the drying time is 24h; the particle size of the pre-made spheres is 20mm.

[0089] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1500℃ and the calcination time is 5h;

[0090] The Al2O3-SiO2-Cr2O3 particles are graded as follows: 45wt% of 3-5mm Al2O3-SiO2-Cr2O3 particles, 30wt% of 1-3mm Al2O3-SiO2-Cr2O3 particles, and 25wt% of 0.1-1mm Al2O3-SiO2-Cr2O3 particles; the Al2O3-SiO2-Cr2O3 particles contain 66-74wt% mullite and 6-8wt% Cr2O3.

[0091] The preparation method of the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance is the same as that in Example 1.

[0092] The performance of the tundish cover castable prepared in Example 2 was tested. When the tundish cover castable was kept at 110℃ for 24h, the room temperature flexural strength was 15MPa. When the tundish cover castable was kept at 1500℃ for 3h, the room temperature flexural strength was 26.2MPa. After keeping the tundish cover castable at 1500℃ for 3h, a slag erosion test was conducted, and no obvious penetration or erosion was observed.

[0093] Example 3

[0094] A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water;

[0095] Based on a total mass ratio of 100% for Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement, the composition is: 68% Al2O3-SiO2-Cr2O3 particles, 13% Al2O3-SiO2-Cr2O3 fine powder, 7% α-Al2O3 micro powder, 8% SiO2 micro powder, and 4% calcium aluminate cement.

[0096] The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; the particle size of the α-Al2O3 micro powder is ≤5μm; the particle size of the SiO2 micro powder is ≤2μm; the particle size of the calcium aluminate cement is 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is ≥71wt%.

[0097] The water-reducing agent is a polycarboxylate-based water-reducing agent; the dosage of the water-reducing agent is 0.1-0.2% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement; the dosage of water is 4.5-6.5% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0098] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0099] 1) 66 wt% Al2O3, 26 wt% SiO2 micro powder and 8 wt% Cr2O3 were mixed and ball-milled in a planetary ball mill to obtain a premixed powder; the ball milling speed was 300 r / min; the ball milling time was 6 h; the Al2O3 was industrial Al2O3; the Al2O3 content of the industrial Al2O3 was ≥97 wt%; the particle size of the Al2O3 was ≤8 μm, the particle size of the SiO2 micro powder was ≤2 μm, and the particle size of the Cr2O3 was ≤5 μm;

[0100] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; the amount of water used is 8 wt% of the premixed powder; the drying temperature is 110℃ and the drying time is 24h; the particle size of the pre-made spheres is 20mm.

[0101] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1500℃ and the calcination time is 5h;

[0102] The Al2O3-SiO2-Cr2O3 particles are graded as follows: 45wt% of 3-5mm Al2O3-SiO2-Cr2O3 particles, 30wt% of 1-3mm Al2O3-SiO2-Cr2O3 particles, and 25wt% of 0.1-1mm Al2O3-SiO2-Cr2O3 particles; the Al2O3-SiO2-Cr2O3 particles contain 66-74wt% mullite and 6-8wt% Cr2O3.

[0103] The preparation method of the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance is the same as that in Example 1.

[0104] The performance of the tundish cover castable prepared in Example 3 was tested. When the tundish cover castable was kept at 110℃ for 24 hours, the room temperature flexural strength was 13.9 MPa. When the tundish cover castable was kept at 1500℃ for 3 hours, the room temperature flexural strength was 22.5 MPa. After keeping the tundish cover castable at 1500℃ for 3 hours, a slag erosion test was conducted, and no obvious penetration or erosion was observed.

[0105] Example 4

[0106] A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water;

[0107] Based on a total mass ratio of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement of 100%, the composition is: 75% Al2O3-SiO2-Cr2O3 particles, 10% Al2O3-SiO2-Cr2O3 fine powder, 5% α-Al2O3 micro powder, 6% SiO2 micro powder, and 4% calcium aluminate cement.

[0108] The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; the particle size of the α-Al2O3 micro powder is ≤5μm; the particle size of the SiO2 micro powder is ≤2μm; the particle size of the calcium aluminate cement is 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is ≥71wt%.

[0109] The water-reducing agent is a polycarboxylate-based water-reducing agent; the dosage of the water-reducing agent is 0.1% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement; the dosage of water is 5% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0110] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0111] 1) 74 wt% Al2O3, 20 wt% SiO2 micro powder and 6 wt% Cr2O3 were mixed and ball-milled in a planetary ball mill to obtain a premixed powder; the ball milling speed was 300 r / min; the ball milling time was 6 h; the Al2O3 was industrial Al2O3; the Al2O3 content of the industrial Al2O3 was ≥97 wt%; the particle size of the Al2O3 was ≤8 μm, the particle size of the SiO2 micro powder was ≤2 μm, and the particle size of the Cr2O3 was ≤5 μm;

[0112] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; the amount of water used is 8 wt% of the premixed powder; the drying temperature is 110℃ and the drying time is 24h; the particle size of the pre-made spheres is 20mm.

[0113] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1600℃ and the calcination time is 5h.

[0114] The Al2O3-SiO2-Cr2O3 particles are graded as follows: 45wt% of 3-5mm Al2O3-SiO2-Cr2O3 particles, 30wt% of 1-3mm Al2O3-SiO2-Cr2O3 particles, and 25wt% of 0.1-1mm Al2O3-SiO2-Cr2O3 particles; the Al2O3-SiO2-Cr2O3 particles contain 66-74wt% mullite and 6-8wt% Cr2O3.

[0115] The preparation method of the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance is the same as that in Example 1.

[0116] The performance of the tundish cover castable prepared in Example 4 was tested. When the tundish cover castable was kept at 110℃ for 24h, the room temperature flexural strength was 15.4MPa. When the tundish cover castable was kept at 1600℃ for 3h, the room temperature flexural strength was 29.5MPa. After keeping the tundish cover castable at 1600℃ for 3h, a slag erosion test was conducted, and no obvious penetration or erosion was observed.

[0117] Example 5

[0118] A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water;

[0119] Based on a total mass ratio of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement of 100%, the composition is: 71% Al2O3-SiO2-Cr2O3 particles, 12% Al2O3-SiO2-Cr2O3 fine powder, 6% α-Al2O3 micro powder, 7% SiO2 micro powder, and 4% calcium aluminate cement.

[0120] The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; the particle size of the α-Al2O3 micro powder is ≤5μm; the particle size of the SiO2 micro powder is ≤2μm; the particle size of the calcium aluminate cement is 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is ≥71wt%.

[0121] The water-reducing agent is a polycarboxylate-based water-reducing agent; the dosage of the water-reducing agent is 0.1% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement; the dosage of water is 5% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0122] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0123] 1) 69 wt% Al2O3, 24 wt% SiO2 micro powder and 7 wt% Cr2O3 were mixed and ball-milled in a planetary ball mill to obtain a premixed powder; the ball milling speed was 300 r / min; the ball milling time was 6 h; the Al2O3 was industrial Al2O3; the Al2O3 content of the industrial Al2O3 was ≥97 wt%; the particle size of the Al2O3 was ≤8 μm, the particle size of the SiO2 micro powder was ≤2 μm, and the particle size of the Cr2O3 was ≤5 μm;

[0124] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; the amount of water used is 8 wt% of the premixed powder; the drying temperature is 110℃ and the drying time is 24h; the particle size of the pre-made spheres is 20mm.

[0125] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1600℃ and the calcination time is 5h.

[0126] The Al2O3-SiO2-Cr2O3 particles are graded as follows: 45wt% of 3-5mm Al2O3-SiO2-Cr2O3 particles, 30wt% of 1-3mm Al2O3-SiO2-Cr2O3 particles, and 25wt% of 0.1-1mm Al2O3-SiO2-Cr2O3 particles; the Al2O3-SiO2-Cr2O3 particles contain 66-74wt% mullite and 6-8wt% Cr2O3.

[0127] The preparation method of the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance is the same as that in Example 1.

[0128] The performance of the tundish cover castable prepared in Example 5 was tested. When the tundish cover castable was kept at 110℃ for 24 hours, the room temperature flexural strength was 16.3 MPa. When the tundish cover castable was kept at 1600℃ for 3 hours, the room temperature flexural strength was 25.6 MPa. After keeping the tundish cover castable at 1600℃ for 3 hours, a slag erosion test was conducted, and no obvious penetration or erosion was observed.

[0129] Example 6

[0130] A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water;

[0131] Based on a total mass ratio of 100% for Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement, the composition is: 68% Al2O3-SiO2-Cr2O3 particles, 13% Al2O3-SiO2-Cr2O3 fine powder, 7% α-Al2O3 micro powder, 8% SiO2 micro powder, and 4% calcium aluminate cement.

[0132] The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; the particle size of the α-Al2O3 micro powder is ≤5μm; the particle size of the SiO2 micro powder is ≤2μm; the particle size of the calcium aluminate cement is 325 mesh; and the Al2O3 content in the pure calcium aluminate cement is ≥71wt%.

[0133] The water-reducing agent is a polycarboxylate-based water-reducing agent; the dosage of the water-reducing agent is 0.1% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement; the dosage of water is 5% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, and water-reducing agent.

[0134] The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps:

[0135] 1) 66 wt% Al2O3, 26 wt% SiO2 micro powder and 8 wt% Cr2O3 were mixed and ball-milled in a planetary ball mill to obtain a premixed powder; the ball milling speed was 300 r / min; the ball milling time was 6 h; the Al2O3 was industrial Al2O3; the Al2O3 content of the industrial Al2O3 was ≥97 wt%; the particle size of the Al2O3 was ≤8 μm;

[0136] 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; the amount of water used is 8 wt% of the premixed powder; the drying temperature is 110℃ and the drying time is 24h; the particle size of the pre-made spheres is 20mm.

[0137] 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1600℃ and the calcination time is 5h.

[0138] The Al2O3-SiO2-Cr2O3 particles are graded as follows: 45wt% of 3-5mm Al2O3-SiO2-Cr2O3 particles, 30wt% of 1-3mm Al2O3-SiO2-Cr2O3 particles, and 25wt% of 0.1-1mm Al2O3-SiO2-Cr2O3 particles; the Al2O3-SiO2-Cr2O3 particles contain 66-74wt% mullite and 6-8wt% Cr2O3.

[0139] The preparation method of the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance is the same as that in Example 1.

[0140] The performance of the tundish cover castable prepared in Example 6 was tested. When the tundish cover castable was kept at 110℃ for 24h, the room temperature flexural strength was 14.5MPa. When the tundish cover castable was kept at 1600℃ for 3h, the room temperature flexural strength was 22.3MPa. After keeping the tundish cover castable at 1600℃ for 3h, a slag erosion test was conducted, and no obvious penetration or erosion was observed.

[0141] The apparent porosity, bulk density, and service life of the intermediate ladle cap castables prepared in Examples 1-6 were tested. The Archimedes drainage test method was used, employing an apparent porosity and bulk density meter (XQK-04, Pruicom, Luoyang, China) to test the samples' apparent porosity and bulk density, with water as the test medium. The service life of the intermediate ladle caps was verified on-site. The results are shown in Table 1.

[0142] Apparent porosity, bulk density, and service life of the intermediate ladle cap castables prepared in Examples 1-6

[0143] Group Apparent porosity / % <![CDATA[Apparent density / g / cm 3 > Service life / time Example 1 14.7±0.2 2.69±0.00 252 Example 2 12.2±0.2 2.81±0.01 268 Example 3 10.4±0.5 3.02±0.00 281 Example 4 15.1±0.2 2.64±0.02 269 Example 5 13.7±0.6 2.79±0.01 289 Example 6 11.8±0.2 2.93±0.01 301

[0144] As shown in Table 1, the intermediate ladle cap castable prepared by this invention has an apparent porosity of 10–15% and a bulk density of 2.6–3.0 g / cm³. 3 Its service life is 250-300 cycles.

[0145] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A tundish cover castable with high thermal shock resistance and high slag erosion resistance, wherein the raw materials for preparing the tundish cover castable are: Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement, water reducing agent and water; Based on a total mass ratio of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, and calcium aluminate cement of 100%, the composition is as follows: 65-75% Al2O3-SiO2-Cr2O3 particles, 10-13% Al2O3-SiO2-Cr2O3 fine powder, 5-8% α-Al2O3 micro powder, 6-10% SiO2 micro powder, and 3-6% calcium aluminate cement. The Al2O3-SiO2-Cr2O3 particles contain 62-76 wt% mullite, 4-8 wt% Cr2O3, and the remaining components; the particle size distribution of the Al2O3-SiO2-Cr2O3 particles is as follows: 40-50 wt% Al2O3-SiO2-Cr2O3 particles of 3-5 mm, 25-40 wt% Al2O3-SiO2-Cr2O3 particles of 1-3 mm, and 10-25 wt% Al2O3-SiO2-Cr2O3 particles of 0.1-1 mm. The particle size of the Al2O3-SiO2-Cr2O3 fine powder is ≤0.088mm; The preparation method of the Al2O3-SiO2-Cr2O3 particles includes the following steps: 1) Mix 66~74wt% Al2O3, 20~26wt% SiO2 micro powder and 4~8wt% Cr2O3 and then ball mill to obtain premixed powder; 2) Add water to the premixed powder obtained in step 1), and then mix, rotary granulate and dry in sequence to obtain pre-made spheres; 3) The preformed spheres obtained in step 2) are calcined and crushed sequentially to obtain Al2O3-SiO2-Cr2O3 particles; the calcination temperature is 1500~1600℃; the calcination time is 4~7h.

2. The intermediate ladle cover castable according to claim 1, characterized in that, The particle size of the α-Al2O3 micro powder is ≤5μm, and the particle size of the SiO2 micro powder is ≤2μm.

3. The intermediate ladle cover castable according to claim 1, characterized in that, The calcium aluminate cement has a particle size of 325 mesh and an Al2O3 content of ≥71wt%.

4. The intermediate ladle cover castable according to claim 1, characterized in that, The amount of water-reducing agent used is 0.1~0.2% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder and calcium aluminate cement.

5. The intermediate ladle cover castable according to claim 1, characterized in that, The amount of water used is 4.5 to 6.8% of the total mass of Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement and water-reducing agent.

6. A method for preparing the intermediate ladle cover castable with high thermal shock resistance and high slag erosion resistance as described in any one of claims 1 to 5, comprising the following steps: (1) Mix Al2O3-SiO2-Cr2O3 particles, Al2O3-SiO2-Cr2O3 fine powder, α-Al2O3 micro powder, SiO2 micro powder, calcium aluminate cement and water-reducing agent, and then add water to mix to obtain a mixture; (2) The mixture obtained in step (1) is successively molded, cured, demolded and baked to obtain intermediate ladle cover casting material with high thermal shock resistance and high slag erosion resistance.

7. The application of the tundish cover castable with high thermal shock resistance and high slag erosion resistance as described in any one of claims 1 to 5, or the tundish cover castable with high thermal shock resistance and high slag erosion resistance prepared by the preparation method described in claim 6, in steelmaking.

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