MgO-Al2O3-SiO2 ternary component tundish covering agent as well as preparation method and application thereof

Abstract

The invention provides a MgO-Al2O3-SiO2 ternary component tundish covering agent and a preparation method and application thereof.The tundish covering agent is composed of a base material and auxiliary materials, the base material is siliceous minerals, and the auxiliary materials comprise expansible minerals and melting point adjusting minerals; the preparation method comprises the following steps that siliceous minerals, expansible minerals and melting point adjusting minerals are crushed and screened, and siliceous mineral particles, expansible mineral particles and melting point adjusting mineral particles are obtained respectively; and the siliceous mineral particles, the expansible mineral particles and the melting point adjusting mineral particles are matched, mixed to be uniform and dried, and the MgO-Al2O3-SiO2 ternary component tundish covering agent is obtained. The tundish covering agent prepared by the invention is good in heat preservation and covering effects, low in cost, simple in preparation process, not easy to crack during slagging-off and high in adhesion to non-metallic inclusions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tundish covering agent for continuous casting steel and iron, in particular to a MgO-Al2O3-SiO2 ternary component tundish covering agent and a preparation method and application thereof. BACKGROUND

[0002] The use of tundish covering agent is related to tapping temperature system, casting smoothness and quality of the casting blank. Therefore, it attracts the attention of the casting industry. With the development of the mechanical industry and the expansion of continuous casting production, and the increase of the capacity of the tundish, the residence time of molten steel in the tundish is correspondingly prolonged. In order to meet the process requirements of the subsequent process, prevent secondary oxidation of molten steel, reduce temperature drop and remove slag, so as to provide molten steel with appropriate temperature to the continuous casting section and ensure smooth casting, a layer of tundish covering agent must be covered on the surface of molten steel in the tundish.

[0003] The early used tundish covering agent mainly includes carbonized rice husk, etc. Although the carbonized rice husk can achieve good heat preservation effect, it seriously pollutes the environment during use and has weak ability to absorb non-metallic oxides. In order to solve this problem, different manufacturers began to use wollastonite, limestone, dolomite, bentonite, fly ash and compound powder as main materials, and fluorite and soda ash as solubilizing agents, and then configure a certain amount of carbonaceous materials to produce tundish covering agent. However, there are still many technical defects, such as fluorite mainly composed of CaF2, which will cause environmental pollution when used; the use of soda ash and compound powder materials leads to high cost of tundish covering agent. Therefore, it is crucial and urgent to manufacture a new type of tundish covering agent which is low in price and environmentally friendly. SUMMARY

[0004] The present application aims to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present application is to provide a preparation method of a MgO-Al2O3-SiO2 ternary component tundish covering agent; the second purpose of the present application is to provide a MgO-Al2O3-SiO2 ternary component tundish covering agent; the third purpose of the present application is to provide an application of a MgO-Al2O3-SiO2 ternary component tundish covering agent.

[0005] In order to achieve the above-mentioned purposes, the present application provides a preparation method of a MgO-Al2O3-SiO2 ternary component tundish covering agent, which comprises the following steps:

[0006] 1) crushing and sieving a siliceous mineral, an expandable mineral and a melting point adjusting mineral to obtain a siliceous mineral granular material, an expandable mineral granular material and a melting point adjusting mineral granular material, respectively;

[0007] 2) proportioning, mixing and drying the siliceous mineral granules, the expandable mineral granules and the melting point adjusting mineral granules to obtain the MgO-Al2O3-SiO2 ternary component tundish covering agent.

[0008] Optionally, the proportioning comprises, by mass fraction: 50-80 parts of the siliceous mineral granules, 10-30 parts of the expandable mineral granules, and 5-20 parts of the melting point adjusting mineral granules.

[0009] Optionally, the mixing comprises placing the proportioned siliceous mineral granules, expandable mineral granules and melting point adjusting mineral granules in a mixer to mix for 15-30 min to obtain a mixed material.

[0010] Optionally, the drying comprises drying the mixed material by sunning or placing in a drying device at 150-300℃ for 10-30 min to obtain a moisture content of ≤1%.

[0011] Optionally, the crushing and screening comprises crushing the siliceous mineral, the expandable mineral and the melting point adjusting mineral to particle size ranges of -70+100 mesh, -20+80 mesh and -90+200 mesh, respectively, using a crushing process with a check screen to obtain the siliceous mineral granules, the expandable mineral granules and the melting point adjusting mineral granules.

[0012] Optionally, the siliceous mineral comprises at least one of quartz, diatomite and zeolite, and the quartz comprises at least one of vein quartz, natural quartz sand, granitic pegmatite and quartzite.

[0013] Optionally, the expandable mineral comprises at least one of perlite, obsidian, pitchstone and vermiculite.

[0014] Optionally, the viscosity adjusting mineral comprises at least one of serpentine, potassium feldspar, sodium feldspar and calcium feldspar, and derivatives thereof, and the derivatives comprise at least one of sanidine, microcline, bytownite and labradorite.

[0015] Another aspect of the present application provides a MgO-Al2O3-SiO2 ternary component tundish covering agent, which is composed of a base material and an auxiliary material, the base material is a siliceous mineral, and the auxiliary material comprises an expandable mineral and a melting point adjusting mineral.

[0016] Optionally, the MgO-Al2O3-SiO2 ternary component tundish covering agent can be prepared by the above preparation method; the melting point of the tundish covering agent is 1300-1450℃, and the high-temperature viscosity is 0.2-0.25 Pa.s.

[0017] In still another aspect, the present application provides a use of a MgO-Al2O3-SiO2 ternary component tundish covering agent, wherein the tundish covering agent comprises the tundish covering agent mentioned above.

[0018] Alternatively, the tundish covering agent is suitable for heat preservation, oxidation prevention, slag removal and crust prevention of molten steel or molten iron in a tundish during steel or iron casting.

[0019] Alternatively, the use method comprises calculating the liquid surface area of the molten steel or molten iron according to the inner diameter of the tundish, and calculating the adding amount, wherein the tundish covering agent is added and dispersed on the liquid surface of the molten steel or molten iron in the tundish, and the adding amount is 1-2 kg / m 2 .

[0020] Compared with the prior art, the present application has the following beneficial effects at least one of which is included:

[0021] (1) The MgO-Al2O3-SiO2 ternary component tundish covering agent of the present application is completely made of natural mineral resources as raw materials, has low price, is environmentally friendly and safe, does not react with molten steel or molten iron during use, and does not produce harmful gases and dust.

[0022] (2) The preparation method of the MgO-Al2O3-SiO2 ternary component tundish covering agent of the present application is simple, and the synthesis and preparation process of compound powder materials is omitted, thereby saving energy and reducing consumption.

[0023] (3) The MgO-Al2O3-SiO2 ternary component tundish covering agent of the present application does not add fluorine-containing substances and raw materials containing phosphorus and sulfur, has stable chemical composition, adjustable melting point, and good covering and heat preservation effects.

[0024] (4) The MgO-Al2O3-SiO2 ternary component tundish covering agent of the present application is not easy to break during slagging, has strong adhesion to non-metallic inclusions, and has good slag removal effect. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other objects and / or characteristics of the present application will become more apparent by describing in detail the present application with reference to the attached drawings, wherein:

[0026] Figure 1 A process flow chart showing the steps of controlled crushing and screening during preparation of the MgO-Al2O3-SiO2 ternary component tundish covering agent of the present application is shown;

[0027] Figure 2 A tundish covering agent prepared in Example 1 of the present application is shown to have good spreading and covering effect on the surface of molten steel;

[0028] Figure 3The spreading and covering effect of the intermediate ladle covering agent prepared in Example 2 of the present application on the surface of molten steel is shown.

[0029] Figure 4 The spreading and covering effect of the intermediate ladle covering agent prepared in Example 3 of the present application on the surface of molten steel is shown.

[0030] Figure 5 The spreading and covering effect of the intermediate ladle covering agent prepared in Comparative Example 1 of the present application on the surface of molten steel is shown.

[0031] Figure 6 The effect of the intermediate ladle covering agent prepared in Example 1 of the present application on the slagging and morphology after use is shown.

[0032] Figure 7 The effect of the intermediate ladle covering agent prepared in Example 2 of the present application on the slagging and morphology after use is shown.

[0033] Figure 8 The effect of the intermediate ladle covering agent prepared in Example 3 of the present application on the slagging and morphology after use is shown. DETAILED DESCRIPTION

[0034] Hereinafter, a MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent and a preparation method and application thereof will be described in detail in conjunction with exemplary embodiments.

[0035] The intermediate ladle covering agent provided by the present application is mainly used for heat preservation, oxidation prevention, slag removal and crust prevention of the surface of molten iron and molten steel in the process of continuous casting production of steel castings, and the acid-base property of the intermediate ladle covering agent is adjusted by controlling the siliceous mineral.

[0036] Exemplary Embodiment 1

[0037] The present exemplary embodiment provides a preparation method of a MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent, which can include the following steps:

[0038] S1, crushing and sieving a siliceous mineral, an expandable mineral and a melting point adjusting mineral to obtain a siliceous mineral granular material, an expandable mineral granular material and a melting point adjusting mineral granular material, respectively.

[0039] In the present embodiment, the siliceous mineral includes at least one of quartz, diatomite and zeolite, and the quartz includes at least one of vein quartz, natural quartz sand, granite pegmatite and quartzite.

[0040] In the present embodiment, the expandable mineral includes at least one of perlite, obsidian, pitchstone and vermiculite.

[0041] In the present embodiment, the viscosity adjusting mineral includes at least one of serpentine, potassium feldspar, sodium feldspar and calcium feldspar and derivatives thereof, the derivatives including at least one of microcline, microperthite, oligoclase and amazonite.

[0042] In the present embodiment, the crushing and screening includes crushing the siliceous mineral, the expandable mineral and the melting point adjusting mineral to a particle size range of -70~+100 mesh, -20~+80 mesh and -90~+200 mesh respectively by using a crushing process with pre-screening and screening, to obtain the siliceous mineral granules, the expandable mineral granules and the melting point adjusting mineral granules.

[0043] In the present embodiment, the siliceous mineral is crushed and screened to -70~+100 mesh, because the siliceous mineral, as an acidity and alkalinity adjusting agent and a base material, can accelerate the fusion and inclusion adsorption reaction in the range of -70~+150 mesh, promote the rapid formation of the lower molten layer, and realize the air isolation and inclusion absorption. The particle size of the expandable mineral such as perlite is controlled in the range of -20~+80 mesh, because the expandable mineral, as a covering agent, is the main thermal insulation raw material, and a larger particle size can effectively form a complete porous lightweight material, prolong the service life of the covering layer, enhance the thermal insulation property, and the melting point adjusting mineral is crushed to -90~+200 mesh, so as to balance the fluxing speed and form a suitable molten layer.

[0044] In the present embodiment, the crushing process with pre-screening and screening is composed of a three-stage closed-circuit crushing with pre-screening and screening and a closed-circuit screening, and the specific process is shown in Figure 1 .

[0045] The three-stage closed-circuit crushing with pre-screening and screening includes coarse crushing, medium crushing and fine crushing in Figure 1 . The coarse crushing is the first-stage granules with a particle size >10 mm after the crushing of the raw ore through a bar screen, and a jaw crusher can be selected. The medium crushing is the second-stage particles obtained by crushing the first-stage granules after the coarse crushing, and a jaw crusher and a cone crusher can be selected. The fine crushing is the third-stage granules obtained by crushing the second-stage particles after the medium crushing, and a jaw crusher, a cone crusher, an impact crusher and a roller crusher can be selected. The fourth-stage granules after the three-stage closed-circuit crushing with pre-screening and screening should be ≤10 mm, and the granules >10 mm are returned to the medium crushing stage. The screening refers to multi-layer screening, and the screening equipment can be selected, such as fixed rod bar screens, arc-shaped bar screen and vibrating rod bar screens.

[0046] The closed-circuit screening refers to crushing and screening the fourth-stage granules, and the crushing is Figure 1The ultrafine crushing in the step S1 can be performed by using a pair of roll crusher, high pressure roller mill, ball mill and autogenous mill. The crushed granular materials are subjected to two-stage screening. The granular materials with size >20 mesh are returned to the crushing stage, and the granular materials with size ≤20 mesh are subjected to second-stage screening to obtain target granular materials (i.e. Figure 1 The granular materials not meeting the requirements are treated separately, such as tailing discarding, etc. The screening equipment can be selected from multi-layer revolving screen and reciprocating vibrating screen. Figure 1

[0047] S2, the siliceous mineral granular materials, expandable mineral granular materials and melting point adjusting mineral granular materials are proportioned, mixed and dried to obtain the MgO-Al2O3-SiO2 ternary component tundish covering agent.

[0048] In the embodiment, the proportioning includes, by mass fraction, 50-80 parts of siliceous mineral granular materials, 10-30 parts of expandable mineral granular materials and 5-20 parts of melting point adjusting mineral granular materials. For example, 51 parts of siliceous mineral granular materials, 29 parts of expandable mineral granular materials and 19 parts of melting point adjusting mineral granular materials; 79 parts of siliceous mineral granular materials, 11 parts of expandable mineral granular materials and 6 parts of melting point adjusting mineral granular materials; 65 parts of siliceous mineral granular materials, 15 parts of expandable mineral granular materials and 10 parts of melting point adjusting mineral granular materials, etc.

[0049] In the embodiment, no additional fluxing agent is added in the raw materials of the preparation method of the present application, and only the siliceous mineral provides the required Si for the covering agent, and the expandable mineral can provide Al and enhance the adsorption and heat preservation performance of the raw materials. At the same time, since the mixed materials contain sufficient basic components such as MgO, Al2O3, K2O, Na2O and SiO2, these components can be provided in the used raw materials, only the contents are different, for example, MgO can be provided by serpentine, Al2O3 can be provided by perlite, K2O can be provided by potassium feldspar, and Na2O can be provided by sodium feldspar.

[0050] In the embodiment, the raw materials can include siliceous mineral, perlite, vermiculite and serpentine. The perlite belongs to high-Si and high-Al raw material, and the Al2O3 content of the perlite can reach about 13%, which can make up for the lack of Al source in the raw materials. In addition, the SiO2 content of the perlite is as high as more than 70%, which can provide sufficient silicon source, so that the stoichiometric ratio of the chemical components in the system can meet the stoichiometry of the tundish covering agent. At the same time, the perlite and vermiculite have excellent expansion performance, and can instantaneously expand to several times of the original size to form light and porous materials at high temperature, thereby improving the adsorption of non-metallic inclusions and heat preservation performance of the covering agent.

[0051] ​In the embodiment, the mixing includes placing the mixed siliceous mineral granular material, the expandable mineral granular material and the melting point adjusting mineral granular material into a mixer and mixing for 15-30 minutes to obtain a mixed material.

[0052] In the embodiment, the drying includes drying the mixed material by sunning or placing the mixed material in a drying device at 150-300℃ for 10-30 minutes to obtain a mixed material with water content ≤1%.

[0053] The purpose of drying to obtain a mixed material with water content ≤1% is that the expandable mineral such as perlite has certain adsorbed water and fissure water on the surface after being mined and broken, which will cause safety hazards when the perlite is used as a slagging agent, such as splashing of molten steel or molten iron when the perlite slagging agent is thrown on the surface of the molten steel or molten iron, which will cause certain safety hazards to the workers. The water must be treated before use.

[0054] Example 2

[0055] The example embodiment provides a MgO-Al2O3-SiO2 ternary component tundish covering agent, which is composed of a base material and an auxiliary material, the base material is a siliceous mineral, and the auxiliary material includes an expandable mineral and a melting point adjusting mineral.

[0056] In the embodiment, the MgO-Al2O3-SiO2 ternary component tundish covering agent can be prepared by the preparation method described in example 1.

[0057] In the embodiment, the melting point of the tundish covering agent is 1300-1450℃, and the high-temperature viscosity is 0.2-0.25 Pa.s.

[0058] Example 3

[0059] The example embodiment provides an application of a MgO-Al2O3-SiO2 ternary component tundish covering agent, which can be prepared by the preparation method described in example 1 or is the tundish covering agent described in example 2.

[0060] In the embodiment, the tundish covering agent is suitable for heat preservation, oxidation prevention, slag removal and crust prevention of molten steel or molten iron in a tundish in the process of steel casting or iron casting.

[0061] In the embodiment, the application method includes calculating the liquid surface area of the molten iron or molten steel according to the inner diameter of the tundish and calculating the addition amount, adding and dispersing the tundish covering agent on the liquid surface of the molten iron or molten steel in the tundish, and the addition amount is 1-2 kg / m 2 .

[0062] In order to better understand the above-mentioned exemplary embodiments of the present application, the following further illustrates them in connection with specific examples.

[0063] Example 1

[0064] In this example, diatomite is used as the base material, and perlite, vermiculite and serpentine are used as the auxiliary materials. The diatomite, perlite, vermiculite and serpentine are subjected to controlled crushing and sieving to obtain granular materials with particle sizes of -70+80 mesh, -20+50 mesh, -60+80 mesh and -90+100 mesh, respectively.

[0065] The granular materials are proportioned by mass fraction, and the diatomite:perlite:vermiculite:serpentine = 50:20:10:20 is weighed, then mixed in a mixer for 60 min. The obtained uniformly mixed covering agent is dried in a drying machine at 200°C for 20 min to control the water content of the covering agent to be less than 1%, thereby obtaining an intermediate ladle covering agent with controllable high-temperature viscosity. The viscosity of the intermediate ladle covering agent is 0.2 Pa.s, and the melting point is 1310°C. The prepared MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent is packaged and sealed.

[0066] The MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent obtained above is subjected to molten steel and molten iron liquid surface covering experiments. The prepared intermediate covering agent is added to the steel liquid surface (the steel type is 45 steel) at a usage amount of 2.5 kg per square meter. The covering agent rapidly expands and spreads to completely cover the steel liquid surface and maintains a good covering layer. The specific effect is shown in Figure 2 The intermediate ladle covering agent can cover the steel liquid surface, and the effective covering time is within 120 s. After working on the 1500°C steel liquid surface, the slag is raked, and the morphology effect is shown in Figure 6 The molten slag is complete and does not appear to be broken.

[0067] Example 2

[0068] In this example, natural quartz sand is used as the base material, and perlite, vermiculite and potassium feldspar are used as the auxiliary materials. The natural quartz sand, perlite, vermiculite and potassium feldspar are subjected to controlled crushing and sieving to obtain granular materials with particle sizes of -70+90 mesh, -30+50 mesh, -70+80 mesh and -100+150 mesh, respectively.

[0069] The granular materials are proportioned according to mass fraction, and the natural quartz sand, perlite, vermiculite and potassium feldspar are weighed in a mass ratio of 70:10:10:10, and then mixed in a mixer for 60 minutes. The mixed and uniform covering agent is dried in a drying machine at 200°C for 20 minutes to control the water content of the covering agent to be less than 1%, so as to obtain the intermediate ladle covering agent with controllable high-temperature viscosity. The viscosity of the intermediate ladle covering agent is 0.22 Pa·s, and the melting point is 1340°C. The prepared MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent is sealed in a bag.

[0070] The MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent obtained above is subjected to molten steel and molten iron liquid surface covering experiment. The prepared intermediate covering agent is added to the steel liquid surface (the type of the steel is 45 steel) at a usage of 2 kg per square meter. The covering agent rapidly expands and spreads to completely cover the steel liquid surface and maintains a good covering layer. The specific effect is shown in Figure 3 The intermediate ladle covering agent can cover the steel liquid surface, and the effective covering time is within 180 seconds. After working on the steel liquid surface at 1500°C, the slag is removed, and the morphology effect is shown in Figure 7 The molten slag is complete and does not appear to be broken.

[0071] Example 3

[0072] In this example, zeolite, perlite, vermiculite and serpentine are controlledly crushed and sieved to obtain granular materials with particle sizes of -80~+100 mesh, -70~+80 mesh, -60~+70 mesh and -150~+200 mesh, respectively.

[0073] The granular materials are proportioned according to mass fraction, and the zeolite, perlite, vermiculite and serpentine are weighed in a mass ratio of 80:5:10:5, and then mixed in a mixer for 60 minutes. The mixed and uniform covering agent is dried in a drying machine at 200°C for 20 minutes to control the water content of the covering agent to be less than 1%, so as to obtain the intermediate ladle covering agent with controllable high-temperature viscosity. The viscosity of the intermediate ladle covering agent is 0.25 Pa·s, and the melting point is 1400°C. The prepared MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent is sealed in a bag.

[0074] The MgO-Al2O3-SiO2 ternary component intermediate ladle covering agent obtained above is subjected to molten steel and molten iron liquid surface covering experiment. The prepared intermediate covering agent is added to the steel liquid surface (the type of the steel is 45 steel) at a usage of 1.5 kg per square meter. The covering agent rapidly expands and spreads to completely cover the steel liquid surface and maintains a good covering layer. The specific effect is shown in Figure 4 The intermediate ladle covering agent can cover the steel liquid surface, and the effective covering time is within 60 seconds. After working on the steel liquid surface at 1500°C, the slag is removed, and the morphology effect is shown in Figure 8As shown, the slag is complete without fracture.

[0075] Comparative Example 1

[0076] The natural quartz sand is used as a base material, and the perlite and the albite are used as auxiliary materials. The natural quartz sand, the perlite and the albite are controlled to be crushed and sieved out of the specified particle size range, and the particle sizes of-200 mesh, -90-+100 mesh and -200 mesh are obtained, respectively.

[0077] The natural quartz sand, the perlite and the albite are weighed according to the mass fraction of 60:30:10, and then mixed in a mixer for 60 min. The obtained mixed uniform covering agent is dried in a drying machine at 200°C for 20 min to control the water content of the covering agent to be less than 1%, so as to obtain the tundish covering agent with controllable high-temperature viscosity. The viscosity of the tundish covering agent is 0.2 Pa.s, and the melting point is 1400°C. The prepared MgO-Al2O3-SiO2 ternary component tundish covering agent is sealed in a bag.

[0078] The molten steel and molten iron liquid surface covering experiment is carried out on the obtained MgO-Al2O3-SiO2 ternary component tundish covering agent. The prepared tundish covering agent is added to the steel liquid surface (the type of steel is 45 steel) at a usage of 1.5 kg per square meter. The tundish covering agent expands and spreads rapidly to completely cover the steel liquid surface, and maintains a good covering layer. The specific effect is shown in Figure 5 As shown, the tundish covering agent can cover the steel liquid surface, and the effective covering time is within 60 s. After working at the steel liquid surface at 1500°C, the slag is complete without fracture, but a large amount of dust appears.

[0079] Although the present application has been described above with reference to the example embodiments and the accompanying drawings, it should be clear for those skilled in the art that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing a ternary intermediate coating agent of MgO-Al2O3-SiO2, characterized in that, The intermediate treasury covering agent is composed of a base material and auxiliary materials. The base material is a siliceous mineral, and the auxiliary materials include expandable minerals and melting point regulating minerals. The preparation method includes the following steps: 1) The siliceous minerals, expandable minerals and melting point regulating minerals are crushed and screened to obtain siliceous mineral granules, expandable mineral granules and melting point regulating mineral granules, respectively. 2) The siliceous mineral particles, expandable mineral particles, and melting point-adjusting mineral particles are proportioned, mixed, and dried to obtain the MgO-Al2O3-SiO2 ternary component intermediate package covering agent.

2. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 1, characterized in that, The proportions mentioned in step 2) include, by mass parts: 50-80 parts of siliceous mineral granules, 10-30 parts of expandable mineral granules, and 5-20 parts of melting point regulating mineral granules.

3. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 1, characterized in that, The mixing described in step 2) involves placing the proportioned siliceous mineral particles, expandable mineral particles, and melting point-adjusting mineral particles into a mixer and mixing for 15-30 minutes to obtain a uniform mixture.

4. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 3, characterized in that, The drying process described in step 2) includes sun-drying the mixture or drying it in a drying device at 150–300°C for 10–30 minutes, so that the moisture content after drying is ≤1%.

5. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 1, characterized in that, The crushing and screening described in step 1) includes using a crushing process with inspection screening to crush siliceous minerals, expandable minerals, and melting point regulating minerals to particle sizes ranging from -70 to +100 mesh, -20 to +80 mesh, and -90 to +200 mesh, respectively, to obtain the siliceous mineral granules, expandable mineral granules, and melting point regulating mineral granules.

6. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 1, characterized in that, The siliceous minerals include at least one of quartz, diatomite, and zeolite, and the quartz includes at least one of vein quartz, natural quartz sand, granite pegmatite, and quartzite.

7. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 1, characterized in that, The expandable minerals include at least one of perlite, obsidian, resinstone, and vermiculite.

8. The preparation method of the MgO-Al2O3-SiO2 ternary component intermediate coating agent according to claim 1, characterized in that, The viscosity-regulating minerals include at least one of serpentine, potassium feldspar, sodium feldspar, and calcium feldspar and their derivatives, wherein the derivatives include at least one of sansobrite, microcline, dextrose, and labradorite.

9. A ternary intermediate packing covering agent of MgO-Al2O3-SiO2, characterized in that, The MgO-Al2O3-SiO2 ternary component intermediate packaging agent is prepared by the method described in any one of claims 1-8; the intermediate packaging agent has a melting point of 1300-1450℃ and a high-temperature viscosity of 0.2-0.25 Pa·s.

10. The application of the MgO-Al2O3-SiO2 ternary component intermediate packaging covering agent according to claim 9, characterized in that, The tundish covering agent is suitable for heat preservation, oxidation prevention, slag removal, and crust prevention of molten steel and iron in the tundish during the casting process of steel and iron.

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