High-chromium steel continuous casting covering slag as well as preparation method and application thereof

Abstract

The invention discloses high-chromium steel continuous casting covering slag as well as a preparation method and application thereof, and relates to the technical field of steel continuous casting metallurgy. The high-chromium steel continuous casting covering slag is prepared from the following chemical components in percentage by mass: 34.0 percent to 36.0 percent of CaO, 30.0 percent to 32.0 percent of SiO2, 6.0 percent to 8.0 percent of Al2O3, 3.5 percent to 5.5 percent of MgO, 6.0 percent to 6.8 percent of Na2O, 3.5 percent to 4.5 percent of F, 4.5 percent to 7.5 percent of B2O3, 1.0 percent to 4.0 percent of graphite and less than or equal to 2.0 percent of impurities. The preparation method comprises raw material pretreatment; adding a fluxing agent; dispersing graphite; and granulating, sintering, screening and packaging. The continuous casting covering slag provided by the invention has the advantages of environmental protection, low consumption and high stability, and by optimizing components and particle size distribution, dust is remarkably reduced, slag strip formation is inhibited, and slag consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of steel continuous casting metallurgy, and in particular to a high-chromium steel continuous casting protection slag and a preparation method and application thereof. Background Art

[0002] Continuous casting mold powder is a crucial auxiliary material in continuous steel casting. Its core functions include preventing secondary oxidation of molten steel, adsorbing inclusions, lubricating the ingot, and controlling heat transfer. Along with the advancement of continuous casting technology, mold powder technology has also continuously advanced. However, facing fierce competition in the steel market and the increasing demand for high-quality and new products from steelmakers, mold powder requirements are becoming increasingly stringent. Whether mold powder technology can meet the demands of comprehensively upgrading continuous casting technology for new products is a common concern for continuous casting plants, mold powder researchers, and manufacturers.

[0003] High chromium steel is an alloy steel with a relatively high chromium content (generally greater than 12wt%). Chromium is its most important alloying element, which can significantly increase the hardness, corrosion resistance and thermal stability of the steel. High chromium steel is a high-performance stainless steel material that is widely favored for its excellent corrosion resistance and high strength. During the continuous casting process of high chromium steel, the protective slag must have good lubricity, melting properties and chemical stability. The existing protective slag is based on silicate and contains CaO, SiO2, Al2O3, Na2O, CaF2 and other components. It is well known that the chemical composition of the continuous casting protective slag matches its performance, and the ratio needs to be adjusted to adapt to the continuous casting requirements of different steel grades (such as high carbon steel, stainless steel, silicon steel). Therefore, how to develop continuous casting protective slag for high chromium steel is also an urgent problem to be solved in the industry.

[0004] In the prior art, continuous casting protection slag generally adopts a formula containing fluoride (such as CaF2) and alkaline oxide (such as Na2O), which has the following defects: ① Traditional protection slag contains a high amount of fluorine (CaF2) (5%-15%), which will release harmful gases such as HF at high temperatures, causing equipment corrosion and environmental pollution; ② There is a lot of dust, and fluoride (F) and Na2O are easily volatile, resulting in serious pollution of the working environment and risks to human health; ③ The friction between the slag film and the crystallizer is aggravated, and local overcooling causes the slag bars to block the molten steel cooling channel; ④ The existing protection slag has insufficient fluidity and needs to be frequently replenished, resulting in high protection slag consumption and increased costs. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0006] To this end, one objective of the present invention is to provide an environmentally friendly, low-consumption, and highly stable high-chromium steel continuous casting mold flux. By optimizing its composition and particle size distribution, it significantly reduces dust, inhibits slag stripe formation, and reduces slag consumption. A second objective of the present invention is to provide a method for preparing the high-chromium steel continuous casting mold flux. A third objective of the present invention is to provide applications for the high-chromium steel continuous casting mold flux.

[0007] A first aspect of the present invention provides a high chromium steel continuous casting protection slag, which includes the following chemical components: CaO, SiO2, Al2O3, MgO, Na2O, F, B2O3, graphite and impurities.

[0008] Furthermore, the high chromium steel continuous casting mold slag includes the following chemical components by mass percentage:

[0009] CaO: 34.0%-36.0%

[0010] SiO2: 30.0%-32.0%

[0011] Al2O3: 6.0%-8.0%

[0012] MgO: 3.5%-5.5%

[0013] Na2O: 6.0%-6.8%

[0014] F: 3.5%-4.5%

[0015] B2O3: 4.5%-7.5%

[0016] Graphite: 1.0%-4.0%

[0017] Impurities: ≤2.0%

[0018] Furthermore, the high chromium steel continuous casting mold slag includes the following chemical components by mass percentage:

[0019] CaO: 35.5%

[0020] SiO2: 31.5%

[0021] Al2O3: 7.3%

[0022] MgO: 4.5%,

[0023] Na2O: 6.4%

[0024] F: 4.0%

[0025] B2O3: 6.5%

[0026] Graphite: 3.5%

[0027] Impurities: 0.8%

[0028] Furthermore, the high chromium steel continuous casting mold slag has a particle size distribution: particles with a particle size of 0.15 mm to 1 mm account for ≥85%, and fine powder with a particle size of <0.15 mm accounts for ≤15%; melting point: 1100°C to 1120°C; viscosity at 1300°C: 0.18 Pa·s to 0.22 Pa·s; specific gravity: 0.75 g / cm 3 -0.80g / cm 3 .

[0029] Furthermore, the high chromium steel has a chromium content ranging from 12.0% to 18.0% by mass.

[0030] A second aspect of the present invention provides a method for preparing high chromium steel continuous casting mold slag, comprising the following steps:

[0031] Raw material pretreatment: according to the stoichiometric ratio of CaO, SiO2, Al2O3 and MgO, ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0032] Flux addition: add Na2CO3, CaF2 and H3BO3 according to the stoichiometric ratio of Na element, F element in Na2O and B element in B2O3, and mix well;

[0033] Graphite dispersion: add graphite with particle size ≤ 20μm, and disperse by high-speed shear at 2000rpm-3000rpm;

[0034] Granulation and sintering: spray granulation, high temperature sintering;

[0035] Screening and packaging: Seal after removing fine powder.

[0036] Furthermore, the spray granulation is performed to form particles with a particle size of 0.15 mm to 1 mm.

[0037] Furthermore, the high temperature sintering is carried out at 800° C.-900° C. for 1 h-2 h.

[0038] The third aspect of the present invention provides an application of a high chromium steel continuous casting protection slag, wherein the above-mentioned high chromium steel continuous casting protection slag is used in the continuous casting of high chromium steel molten steel to prepare high chromium steel billets.

[0039] Furthermore, the usage of high chromium steel continuous casting protection slag is 1.5kg / ton high chromium steel liquid to 2.0kg / ton high chromium steel liquid.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] The high-chromium steel continuous casting mold slag provided by the present invention reduces volatile dust, lowering dust concentration by 45%-50%. It also enhances the thermal shock resistance of the slag film. It reduces slag streaks, reducing their incidence by 60%-65%. It also inhibits steel-slag interfacial reactions and improves slag film stability. The high-chromium steel continuous casting mold slag provided by the present invention optimizes slag consumption, reducing it by 22%-28%. DETAILED DESCRIPTION

[0042] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0043] According to a first aspect of an embodiment of the present invention, a high-chromium steel continuous casting protective slag is provided, comprising the following chemical components: CaO, SiO2, Al2O3, MgO, Na2O, F, B2O3, graphite and impurities.

[0044] As is known to all, due to different compositions, the high-temperature solidification and shrinkage characteristics and high-temperature mechanical properties of steel vary greatly. The taper of the wide-side crystallizer of tubular crystallizers and slabs is usually basically fixed during the production process and difficult to adjust dynamically with the type of steel. The parameters of the crystallizer cooling water are also basically fixed during the casting process. Therefore, in order to change the heat transfer in the meniscus area and the lubrication of the cast billet to achieve the production of defect-free billets, this can only be achieved by changing the composition and properties of the added protective slag after optimizing the molten steel flow field and crystallizer parameters. The chemical composition of the continuous casting protective slag matches its properties, so it is necessary to adjust the composition and proportion of the continuous casting protective slag for different steel grades to adapt to different steel grades. The high-chromium steel targeted by this application has a chromium content in the range of 12.0%-18.0% by mass. Chromium can improve the high-temperature performance and deep hardenability of molten steel, thereby increasing the casting speed. However, when the chromium content is too high, it is easy to cause poor cooling of the crystallizer, which causes fracture during the continuous casting process. Moreover, during the continuous casting process, chromium will affect the crystallization process and microstructure of the steel. Chromium and carbon form a variety of carbides, which affect the phase change behavior and solidification characteristics of steel. High chromium content will increase the brittleness and thermal cracking tendency of steel, affecting the quality of the ingot. In addition, chromium will also cause dendritic segregation, further affecting the plasticity and uniformity of steel. Therefore, how to develop continuous casting protective slag for high chromium steel is an urgent problem to be solved in the industry. Through a large number of experiments by the inventors of this application, the composition and ratio of the chemical components in the protective slag have been optimized, so that the prepared protective slag reduces volatile dust, enhances the thermal shock resistance of the slag film, reduces the formation of slag strips, inhibits the steel-slag interface reaction, and improves the stability of the slag film.

[0045] In some feasible embodiments, the high-chromium steel continuous casting mold slag comprises the following chemical components by mass: CaO: 34.0%-36.0%, SiO2: 30.0%-32.0%, Al2O3: 6.0%-8.0%, MgO: 3.5%-5.5%, Na2O: 6.0%-6.8%, F: 3.5%-4.5%, B2O3: 4.5%-7.5%, graphite: 1.0%-4.0%, and impurities: ≤2.0%. Preferably, the chemical components by mass are: CaO: 35.5%, SiO2: 31.5%, Al2O3: 7.3%, MgO: 4.5%, Na2O: 6.4%, F: 4.0%, B2O3: 6.5%, graphite: 3.5%, and impurities: 0.8%.

[0046] Specifically, this invention reduces volatile dust by reducing the Na2O content and optimizing the particle size, reducing dust emissions by 45%-50%. Increasing the MgO content enhances the thermal shock resistance of the slag film. In this invention, B2O3 lowers the melting point and graphite provides high-temperature lubrication. The synergistic effect of B2O3 and graphite reduces slag streak formation, reducing the incidence by 60%-65%. The Al2O3-MgO strengthening effect inhibits slag interfacial reactions and improves slag film stability. B2O3 fluxing and viscosity control optimize slag consumption, reducing it by 22%-28%.

[0047] In some feasible embodiments, the high chromium steel continuous casting mold slag provided by the present invention has a particle size distribution: particles with a particle size of 0.15 mm to 1 mm account for ≥85%, and fine powder with a particle size <0.15 mm accounts for ≤15%; melting point: 1100°C to 1120°C; viscosity at 1300°C: 0.18 Pa·s to 0.22 Pa·s; specific gravity: 0.75 g / cm 3 -0.80g / cm 3 .

[0048] Specifically, when there are too many fine powders with a particle size of <0.15mm, the dust pollution problem is aggravated, resulting in serious pollution of the working environment and risks to human health. When there are too many particles with a particle size >1mm, the protective slag will not melt evenly during the continuous casting process, affecting the continuity of the slag film. The present invention optimizes the particle size to control the proportion of 0.15mm-1mm particles to ≥85%, balances fluidity and dust control, reduces volatile dust, and reduces dust by 45%-50%. After a large number of experiments, the present invention found that lowering the melting point is beneficial to increasing the thickness of the slag film and facilitating lubrication. The melting point mainly depends on the composition of the protective slag. The present invention has screened the components and proportions through a large number of experiments by the inventors, and reduced the melting point of the prepared protective slag. The viscosity of the protective slag is an important parameter for controlling the heat transfer and lubrication between the crystallizer and the ingot. The appropriate viscosity value is the key to ensuring that the slag can smoothly fill the channel between the crystallizer and the ingot shell, ensure the thickness of the slag film, ensure a reasonable heat transfer rate, and ensure lubrication. If the viscosity is too high, the molten protective slag will not easily penetrate into the gap between the crystallizer and the billet, and the lubrication condition of the billet will deteriorate, making it difficult to pull the billet shell out of the crystallizer, and even causing a sticky steel leak accident. If the viscosity is too low, a large amount of molten protective slag will flow into the gap between the crystallizer and the billet, and the lubrication and heat transfer of the billet will be uneven, resulting in surface cracks and waste products. Through a large number of experiments by the inventors and the screening of components and proportions, the present invention controls the viscosity (1300°C) between 0.18Pa·s-0.22Pa·s, ensuring that the slag can smoothly fill the channel between the crystallizer and the billet shell, ensuring the thickness of the slag film and ensuring lubrication. The high chromium steel continuous casting protective slag prepared by the present invention through the screening of components and proportions has a specific gravity of 0.75g / cm 3 -0.80g / cm 3 It is easier to evenly cover the surface of the molten steel.

[0049] A second aspect of the embodiments of the present invention provides a method for preparing high chromium steel continuous casting mold slag, comprising the following steps:

[0050] Raw material pretreatment: according to the stoichiometric ratio of CaO, SiO2, Al2O3 and MgO, ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0051] Flux addition: add Na2CO3, CaF2 and H3BO3 according to the stoichiometric ratio of Na element, F element in Na2O and B element in B2O3, and mix well;

[0052] Graphite dispersion: add graphite with particle size ≤ 20μm, and disperse by high-speed shear at 2000rpm-3000rpm;

[0053] Granulation and sintering: spray granulation, high temperature sintering;

[0054] Screening and packaging: Seal after removing fine powder.

[0055] Specifically, the present invention generates Na2O by adding Na2CO3, generates F by adding CaF2, generates B2O3 by adding H3BO3, and ensures uniform dispersion of graphite by controlling the high-speed shear dispersion speed.

[0056] In some feasible embodiments, spray granulation is performed to form particles with a particle size of 0.15 mm to 1 mm.

[0057] Specifically, excessive amounts of fine powder with a particle size of less than 0.15 mm exacerbate dust pollution, leading to severe environmental pollution and risks to human health. Excessive amounts of particles with a particle size greater than 1 mm lead to uneven melting of the mold slag during continuous casting, affecting the continuity of the slag film. This invention optimizes particle size to control the proportion of particles between 0.15 mm and 1 mm to ≥ 85%, balancing fluidity and dust control, reducing volatile dust and achieving a 45%-50% reduction in dust.

[0058] In some feasible implementations, high temperature sintering is performed at 800° C.-900° C. for 1 h-2 h.

[0059] Specifically, sintering temperature has a significant impact on mold slag preparation. Excessively high sintering temperatures (>900°C) can lead to excessive volatilization of the generated B₂O₃, reducing the fluxing effect; while low sintering temperatures (<800°C) result in incomplete sintering, insufficient particle strength, and the generation of dust. Therefore, the preferred sintering temperature in the present invention is 800°C-900°C to achieve a balance between volatilization and sintering effectiveness.

[0060] A third aspect of the present invention provides an application of a high chromium steel continuous casting mold slag, wherein the above-mentioned high chromium steel continuous casting mold slag is used in the continuous casting of high chromium steel molten steel to prepare high chromium steel billets.

[0061] In some feasible implementations, the usage of high chromium steel continuous casting protection slag is 1.5 kg / ton high chromium steel liquid to 2.0 kg / ton high chromium steel liquid.

[0062] Specifically, the present invention optimizes slag consumption by fluxing with B2O3 and controlling viscosity, thereby reducing slag consumption by 22%-28%.

[0063] Example 1 A high chromium steel continuous casting mold slag and its preparation method

[0064] 1. Composition and proportion of high chromium steel continuous casting mold slag

[0065] High chromium steel continuous casting mold slag includes the following chemical components by mass percentage:

[0066] CaO: 34.0%

[0067] SiO2: 30.0%

[0068] Al2O3: 6.0%

[0069] MgO: 5.5%

[0070] Na2O: 6.8%

[0071] F: 4.5%

[0072] B2O3: 7.5%

[0073] Graphite: 4.0%

[0074] Impurities: 1.7%

[0075] 2. Preparation method, comprising the following steps:

[0076] 1. Raw material pretreatment: Take CaO, SiO2, Al2O3 and MgO according to stoichiometric ratio, and ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0077] 2. Add flux: According to the stoichiometric ratio of Na element, F element in Na2O and B element in B2O3, add Na2CO3, CaF2 and H3BO3 and mix well.

[0078] 3. Graphite dispersion: Add flake graphite with a particle size of ≤20μm and disperse at a high speed of 2000rpm;

[0079] 4. Granulation and sintering: The obtained mixture is spray granulated to form particles with a particle size of 0.15mm-1mm, and sintered at a high temperature of 850℃ for 1.5h;

[0080] 5. Screening and packaging: seal after removing fine powder.

[0081] 3. Performance is shown in Table 1.

[0082] IV. Application

[0083] During the continuous casting process of high chromium steel, the chromium content in the molten steel is 15wt%. Continuous casting mold slag is added during the continuous casting process of the high chromium steel molten steel to prepare high chromium steel billets. The amount of the high chromium steel continuous casting mold slag is 1.95kg / ton of high chromium steel molten steel.

[0084] Example 2 A high chromium steel continuous casting mold slag and its preparation method

[0085] 1. Composition and proportion of high chromium steel continuous casting mold slag

[0086] High chromium steel continuous casting mold slag includes the following chemical components by mass percentage:

[0087] CaO: 35.5%

[0088] SiO2: 31.5%

[0089] Al2O3: 7.3%

[0090] MgO: 4.5%

[0091] Na2O: 6.4%

[0092] F: 4.0%

[0093] B2O3: 6.5%

[0094] Graphite: 3.5%

[0095] Impurities: 0.8%

[0096] 2. Preparation method, comprising the following steps:

[0097] 1. Raw material pretreatment: Take CaO, SiO2, Al2O3 and MgO according to stoichiometric ratio, and ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0098] 2. Add flux: According to the stoichiometric ratio of Na element, F element in Na2O and B element in B2O3, add Na2CO3, CaF2 and H3BO3 and mix well.

[0099] 3. Graphite dispersion: Add flake graphite with a particle size of ≤20μm and disperse at a high speed of 2000rpm;

[0100] 4. Granulation and sintering: The obtained mixture is spray granulated to form particles with a particle size of 0.15mm-1mm, and sintered at a high temperature of 850℃ for 1.5h;

[0101] 5. Screening and packaging: seal after removing fine powder.

[0102] 3. Performance is shown in Table 1.

[0103] IV. Application

[0104] During the continuous casting process of high chromium steel, the chromium content in the molten steel is 15wt%. Continuous casting mold slag is added during the continuous casting process of the high chromium steel molten steel to prepare high chromium steel billets. The amount of the high chromium steel continuous casting mold slag is 1.8kg / ton of high chromium steel molten steel.

[0105] Example 3 A high chromium steel continuous casting mold slag and its preparation method

[0106] 1. Composition and proportion of high chromium steel continuous casting mold slag

[0107] High chromium steel continuous casting mold slag includes the following chemical components by mass percentage:

[0108] CaO: 36.0%

[0109] SiO2: 32.0%

[0110] Al2O3: 8.0%

[0111] MgO: 4.2%

[0112] Na2O: 6.3%

[0113] F: 3.5%

[0114] B2O3: 4.5%,

[0115] Graphite: 4.0%

[0116] Impurities: 1.5%

[0117] 2. Preparation method, comprising the following steps:

[0118] 1. Raw material pretreatment: Take CaO, SiO2, Al2O3 and MgO according to stoichiometric ratio, and ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0119] 2. Add flux: According to the stoichiometric ratio of Na element, F element in Na2O and B element in B2O3, add Na2CO3, CaF2 and H3BO3 and mix well.

[0120] 3. Graphite dispersion: Add flake graphite with a particle size of ≤20μm and disperse at a high speed of 3000rpm;

[0121] 4. Granulation and sintering: The obtained mixture is spray granulated to form particles with a particle size of 0.15mm-1mm, and sintered at a high temperature of 850℃ for 1.5h;

[0122] 5. Screening and packaging: seal after removing fine powder.

[0123] 3. Performance is shown in Table 1.

[0124] IV. Application

[0125] During the continuous casting process of high chromium steel, the chromium content in the molten steel is 15wt%. Continuous casting mold slag is added during the continuous casting process of the high chromium steel molten steel to prepare high chromium steel billets. The amount of the high chromium steel continuous casting mold slag is 1.875kg / ton of high chromium steel molten steel.

[0126] Comparative Example 1 Continuous casting mold slag and preparation method thereof

[0127] 1. Composition and proportion of continuous casting mold slag

[0128] The continuous casting mold slag does not contain B2O3 and graphite, and includes the following chemical components by mass percentage:

[0129] CaO: 36.64%

[0130] SiO2: 32.77%

[0131] Al2O3: 5.72%

[0132] MgO: 2.7%

[0133] Na2O: 10.5%

[0134] F: 6.89%

[0135] Impurities: 4.78%

[0136] 2. Preparation method, comprising the following steps:

[0137] 1. Raw material pretreatment: Take CaO, SiO2, Al2O3 and MgO according to stoichiometric ratio, and ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0138] 2. Add flux: add Na2CO3 and CaF2 according to the stoichiometric ratio of Na and F in Na2O and mix well;

[0139] 3. Granulation and sintering: The obtained mixture is spray granulated to form particles with a particle size of 0.15mm-1mm, and sintered at a high temperature of 850℃ for 1.5h;

[0140] 4. Screening and packaging: seal after removing fine powder.

[0141] 3. Performance is shown in Table 1.

[0142] IV. Application

[0143] During the continuous casting process of high chromium steel, the chromium content in the molten steel is 15wt%. Continuous casting mold slag is added during the continuous casting process of the high chromium steel molten steel to prepare high chromium steel billets. The amount of the high chromium steel continuous casting mold slag is 2.5kg / ton of high chromium steel molten steel.

[0144] Comparative Example 2 Continuous casting mold slag and preparation method thereof

[0145] 1. Composition and proportion of continuous casting mold slag

[0146] The continuous casting mold slag does not contain B2O3 and graphite, and includes the following chemical components by mass percentage:

[0147] CaO: 34.0%

[0148] SiO2: 30.0%

[0149] Al2O3: 7.0%

[0150] MgO: 3.0%

[0151] Na2O: 15.0%

[0152] F: 6.5%

[0153] Impurities: 4.5%

[0154] 2. Preparation method, comprising the following steps:

[0155] 1. Raw material pretreatment: Take CaO, SiO2, Al2O3 and MgO according to stoichiometric ratio, and ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm;

[0156] 2. Add flux: add Na2CO3 and CaF2 according to the stoichiometric ratio of Na and F in Na2O and mix well;

[0157] 3. Granulation and sintering: The obtained mixture is spray granulated to form particles with a particle size of 0.15mm-1mm, and sintered at a high temperature of 850℃ for 1.5h;

[0158] 4. Screening and packaging: seal after removing fine powder.

[0159] 3. Performance is shown in Table 1.

[0160] IV. Application

[0161] During the continuous casting process of high chromium steel, the chromium content in the molten steel is 15wt%. Continuous casting mold slag is added during the continuous casting process of the high chromium steel molten steel to prepare high chromium steel billets. The amount of the high chromium steel continuous casting mold slag is 3.0kg / ton of high chromium steel molten steel.

[0162] Table 1 Performance of continuous casting mold slag of Examples 1-3 and Comparative Examples 1-2

[0163]

[0164] As shown in Table 1, the high-chromium steel continuous casting mold slag prepared according to the present invention has a melting point between 1100°C and 1120°C, lower than the melting points of Comparative Example 1 (1150°C) and Comparative Example 2 (1180°C). This is because the mold slags provided in Comparative Examples 1 and 2 have higher melting points due to the lack of fluxing from B₂O₃. The present invention lowers the melting point of the continuous casting mold slag, effectively maintaining its movement around the shell without solidifying. Furthermore, this lower melting point facilitates increased slag film thickness and facilitates lubrication.

[0165] As shown in Table 1, the viscosity (1300°C) of the high-chromium steel continuous casting mold slag prepared by the present invention ranges from 0.18 Pa·s to 0.22 Pa·s, which is lower than the viscosity of Comparative Example 1 (0.35 Pa·s) and Comparative Example 2 (0.40 Pa·s). This is because the mold slags provided in Comparative Examples 1 and 2 lack graphite lubrication, resulting in increased viscosity and poor fluidity. The present invention reduces the viscosity of the mold slag, ensuring that the slag can smoothly fill the channel between the crystallizer and the shell, maintaining a thick slag film and ensuring lubrication.

[0166] As can be seen from Table 1, the high chromium steel continuous casting mold slag prepared by the present invention has a specific gravity of 0.75g / cm 3 -0.80g / cm 3 The specific gravity is lower than that of the comparative example 1 (0.85g / cm 3 ) and the specific gravity of comparative example 2 (0.90g / cm 3 ). The present invention adopts a lightweight graphite design, which makes it easier to evenly cover the surface of the molten steel than Comparative Examples 1 and 2.

[0167] Taking the continuous casting mold slag prepared in Comparative Example 1 as the benchmark, Table 1 shows that the dust concentration of the high-chromium steel continuous casting mold slag prepared in Example 1 was 55%, a 45% reduction compared to Comparative Example 1. The dust concentration of the high-chromium steel continuous casting mold slag prepared in Example 2 was 50%, a 50% reduction compared to Comparative Example 1. The dust concentration of the high-chromium steel continuous casting mold slag prepared in Example 3 was 52%, a 48% reduction compared to Comparative Example 1.

[0168] Using the continuous casting mold slag prepared in Comparative Example 1 as the benchmark, Table 1 shows that the slag bar formation rate of the high-chromium steel continuous casting mold slag prepared in Example 1 was 12%, a 60% reduction compared to Comparative Example 1. The slag bar formation rate of the high-chromium steel continuous casting mold slag prepared in Example 2 was 10.5%, a 65% reduction compared to Comparative Example 1. The slag bar formation rate of the high-chromium steel continuous casting mold slag prepared in Example 3 was 11.1%, a 63% reduction compared to Comparative Example 1.

[0169] Taking the continuous casting mold slag prepared in Comparative Example 1 as the benchmark, Table 1 shows that the high-chromium steel continuous casting mold slag prepared in Example 1 consumed 1.95 kg of slag per ton of molten steel, which is 78% of the amount used in Comparative Example 1 and a 22% reduction compared to Comparative Example 1. The high-chromium steel continuous casting mold slag prepared in Example 2 consumed 1.8 kg of slag per ton of molten steel, which is 72% of the amount used in Comparative Example 1 and a 28% reduction compared to Comparative Example 1. The high-chromium steel continuous casting mold slag prepared in Example 3 consumed 1.875 kg of slag per ton of molten steel, which is 75% of the amount used in Comparative Example 1 and a 25% reduction compared to Comparative Example 1.

[0170] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application. The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application. These improvements and variations should also be regarded as the scope of protection of the present application.

Claims

1. A high chromium steel continuous casting mold slag, characterized in that: The high chromium steel continuous casting protection slag includes the following chemical components: CaO, SiO2, Al2O3, MgO, Na2O, F, B2O3, graphite and impurities.

2. The high chromium steel continuous casting mold slag according to claim 1, characterized in that: The high chromium steel continuous casting mold slag includes the following chemical components by mass percentage: CaO: 34.0%-36.0%, SiO2: 30.0%-32.0%, Al2O3: 6.0%-8.0%, MgO: 3.5%-5.5%, Na2O: 6.0%-6.8%, F：3.5％-4.5％、 B2O3: 4.5%-7.5%, Graphite: 1.0%-4.0%, Impurities: ≤2.0%.

3. The high chromium steel continuous casting mold slag according to claim 2, characterized in that: The high chromium steel continuous casting mold slag includes the following chemical components by mass percentage: CaO: 35.5%, SiO2: 31.5%, Al2O3: 7.3%, MgO: 4.5%, Na2O: 6.4%, F：4.0％、 B2O3: 6.5%, Graphite: 3.5%, Impurities: 0.8%.

4. The high chromium steel continuous casting mold slag according to any one of claims 1 to 3, characterized in that: The high chromium steel continuous casting mold slag has a particle size distribution of: particles with a particle size of 0.15 mm to 1 mm account for ≥85%, and fine powder with a particle size of <0.15 mm accounts for ≤15%; a melting point of 1100° C. to 1120° C.; a viscosity at 1300° C. of 0.18 Pa·s to 0.22 Pa·s; and a specific gravity of 0.75 g / cm 3 -0.80g / cm 3 .

5. The high chromium steel continuous casting mold slag according to any one of claims 1 to 3, characterized in that: The high chromium steel has a chromium content ranging from 12.0% to 18.0% by mass.

6. A method for preparing high chromium steel continuous casting mold slag, characterized in that: The method for preparing a high chromium steel continuous casting mold slag according to any one of claims 1 to 5 comprises the following steps: Raw material pretreatment: according to the stoichiometric ratio of CaO, SiO2, Al2O3 and MgO, ball-mill CaO, SiO2, Al2O3 and MgO to a particle size of ≤50μm; Flux addition: add Na2CO3, CaF2 and H3BO3 according to the stoichiometric ratio of Na element, F element in Na2O and B element in B2O3, and mix well; Graphite dispersion: add graphite with particle size ≤ 20μm, and disperse by high-speed shear at 2000rpm-3000rpm; Granulation and sintering: spray granulation, high temperature sintering; Screening and packaging: Seal after removing fine powder.

7. The method for preparing high chromium steel continuous casting mold slag according to claim 6, characterized in that: The spray granulation is performed to form particles with a particle size of 0.15 mm to 1 mm.

8. The method for preparing high chromium steel continuous casting mold slag according to claim 6, characterized in that: The high temperature sintering is carried out at 800° C.-900° C. for 1 h-2 h.

9. An application of high chromium steel continuous casting mold slag, characterized in that: Use of the high chromium steel continuous casting protection slag according to any one of claims 1 to 5 in the continuous casting of high chromium steel molten steel to prepare high chromium steel billets.

10. The use of a high chromium steel continuous casting mold slag according to claim 9, characterized in that: The dosage of high chromium steel continuous casting protection slag is 1.5kg / ton high chromium steel liquid to 2.0kg / ton high chromium steel liquid.

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