Desulfurizer for rh furnace and preparation method and application thereof

Abstract

The application provides a desulfurizer for RH furnace and a preparation method and application thereof. A mixed raw material powder is subjected to melting treatment to obtain a liquid material. The mixed raw material powder comprises a CaO-containing powder, an Al2O3-containing powder and optionally a fluorine-containing powder. The liquid material is cooled and solidified to room temperature to precipitate free calcium oxide microcrystals, thereby obtaining a solid material, and a desulfurizer for RH furnace is obtained. The desulfurizer for RH furnace comprises calcium fluoroaluminate and / or calcium aluminate, and the calcium fluoroaluminate and / or the calcium aluminate contain the free calcium oxide microcrystals. The desulfurizer for RH furnace provided by the application has improved desulfurization effect.

Description

Technical Field

[0001] This application relates to the field of iron and steel smelting technology, and in particular to desulfurizing agents for RH furnaces, their preparation methods, and applications. Background Technology

[0002] Desulfurizing agents for RH furnaces often experience unstable desulfurization rates during application. There are several reasons for this instability, one of which is the inconsistent amount of residue in the vacuum chamber during the desulfurization process. The main components of the residue in the vacuum chamber typically include at least 80% acidic oxides such as Al2O3 and SiO2. These residues reduce the CaO activity of the desulfurizing agent, thus affecting the desulfurization effect. Summary of the Invention

[0003] Based on this, this application provides a desulfurizing agent for RH furnaces, its preparation method, and its application, aiming to improve the desulfurization effect of the desulfurizing agent for RH furnaces.

[0004] The first aspect of this application provides a method for preparing a desulfurizing agent for an RH furnace, comprising:

[0005] The mixed raw material powder is melted to obtain a liquid material, wherein the mixed raw material powder includes powder containing CaO, powder containing Al2O3, and optionally fluorine-containing powder;

[0006] The liquid material is cooled and solidified to room temperature, and free calcium oxide microcrystals are precipitated to obtain a solid material, which is used to prepare a desulfurizing agent for RH furnaces; the desulfurizing agent for RH furnaces includes calcium fluoroaluminate and / or calcium aluminate, and the calcium fluoroaluminate and / or the calcium aluminate contains the free calcium oxide microcrystals.

[0007] In some embodiments of this application, one or more of the following conditions are met:

[0008] (1) The mass fraction of the free calcium oxide microcrystals in the desulfurizing agent for the RH furnace is 5%~30%, and can be selected as 10%~30%;

[0009] (2) The particle size of the free calcium oxide microcrystals is greater than 0 μm and less than or equal to 500 μm.

[0010] In some embodiments of this application, one or more of the following conditions are met:

[0011] (1) The mass fraction w of CaO in the RH furnace desulfurizing agent satisfies the following condition: w = yx / 1.2;

[0012] Where x is the mass fraction of CaF2 in the RH furnace desulfurizer, x is 0%~35%, and y is 60%~75%;

[0013] (2) The desulfurizing agent for the RH furnace includes the following components by mass fraction: CaO 45%~65%, CaF2 0%~35%, Al2O3 15%~45%, SiO2 0%~8%, MgO≤8%, and impurities 0%~3%.

[0014] In some embodiments of this application, the particle size of the CaO-containing powder, the Al2O3-containing powder, and the fluorine-containing powder is independently greater than 0 mm and less than or equal to 3 mm.

[0015] In some embodiments of this application, the CaO-containing powder includes lime powder and / or limestone powder, the Al2O3-containing powder includes alumina powder, and the fluorine-containing powder includes fluorite powder.

[0016] In some embodiments of this application, melting the mixed raw material powder includes:

[0017] The mixed raw material powder is heated to a target temperature, which is 1400℃~1550℃;

[0018] Keep warm at the target temperature for at least 15 minutes;

[0019] Optionally, gas stirring is used during the heating and / or heat preservation process to homogenize the liquid material; the gas stirring uses nitrogen and / or argon.

[0020] In some embodiments of this application, the cooling rate for cooling and solidifying the liquid material to 500°C is 100°C / min to 1000°C / min.

[0021] In some embodiments of this application, the above preparation method further includes:

[0022] The solid material is crushed to obtain crushed material;

[0023] Optionally, after obtaining the crushed material, the process further includes: mixing lime particles into the crushed material to prepare the RH furnace desulfurizing agent, wherein the mass fraction of the lime particles in the RH furnace desulfurizing agent is 0-15%, and the total mass fraction of the free calcium oxide microcrystals and the lime particles in the RH desulfurizing agent is 5%-30%.

[0024] Optionally, the particle size of the crushed material is 3mm to 50mm, and optionally 3mm to 20mm;

[0025] Optionally, the particle size of the lime particles is 3mm to 50mm, and can be 3mm to 20mm.

[0026] Optionally, the absolute value of the difference between the average particle size of the lime particles and the average particle size of the crushed material is ≤5mm.

[0027] The second aspect of this application provides a desulfurizing agent for an RH furnace, which is prepared according to the preparation method of the first aspect of this application.

[0028] The third aspect of this application provides the application of the RH furnace desulfurizing agent of the second aspect of this application in RH furnace desulfurization.

[0029] The preparation method provided in this application involves melting a mixed raw material powder containing CaO powder, followed by cooling and solidification. During the cooling and solidification process, solid calcium fluoroaluminate and / or calcium aluminate are formed, and free calcium oxide microcrystals are also precipitated. This results in the RH furnace desulfurizer containing highly active free calcium oxide microcrystals. Compared to directly using CaO powder as the desulfurizer, these free calcium oxide microcrystals have a larger specific surface area, more lattice defects, and higher desulfurization reactivity, thus exhibiting higher desulfurization efficiency and improving the desulfurization effect of the RH furnace desulfurizer. Attached Figure Description

[0030] Figure 1 The histograms show the desulfurization rates of the desulfurizing agents used in RH furnaces in Examples 1-6 and Comparative Example 1.

[0031] Figure 2 The diagram shows the desulfurization rate range of the desulfurizing agent for the RH furnace in Examples 1-6 and Comparative Example 1.

[0032] Figure 3 The diagram shows the working condition of the impregnation tube of the RH furnace when the desulfurizing agent of Comparative Example 1 is used for desulfurization of the RH furnace.

[0033] Figure 4 The diagram shows the working condition of the impregnation tube of the RH furnace when the desulfurizing agent of RH furnace in Example 1 is used for desulfurization of RH furnace. Detailed Implementation

[0034] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0035] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value or with other lower or upper limits to form a range not explicitly stated.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. It should be noted that, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items, "above," "below," includes the stated number, and "one or more" with "multiple" means two or more.

[0037] In this document, when referring to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of selectable values ​​within a numerical interval is considered continuous, and includes the two endpoints (i.e., the minimum and maximum values) of the numerical interval, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, and other numerical interval types.

[0038] In this document, for methods involving multiple steps, unless otherwise explicitly stated herein, there is no strict order constraint on the execution of these steps; they may be executed in any order other than those described. Moreover, any step may include multiple sub-steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and their execution order is not necessarily sequential, but may be executed in turn, alternately, or simultaneously with other steps or parts of the sub-steps or stages of other steps.

[0039] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0040] To achieve high desulfurization efficiency in RH furnace desulfurizers, two conditions need to be considered: first, the desulfurizer must be able to melt rapidly to form a liquid phase, meaning it must have a low melting point and high melting rate; second, the desulfurizer must have high CaO activity to promote desulfurization. However, generally speaking, high CaO activity in the desulfurizer usually means a higher melting point and a lower melting rate. Therefore, optimizing these two conditions is often contradictory. In view of this, a common technical solution to improve the desulfurization effect is to use high-activity calcium oxide directly as the desulfurizer, and physically mix a small amount of fluorite (CaF2) into the calcium oxide as a flux to accelerate melting. However, directly using highly active CaO as the desulfurizer, and with a large mass proportion of CaO in the desulfurizer (e.g., exceeding 30%), is extremely detrimental to the refractory materials in the RH furnace. In continuous large-scale production, it often easily causes severe non-uniform erosion of the refractory materials, leading to shutdown accidents; moreover, the desulfurization effect of this solution is not ideal. In view of this, the present application proposes the following technical solution.

[0041] In a first aspect, this application provides a method for preparing a desulfurizing agent for an RH furnace, which may include the following steps:

[0042] S1. The mixed raw material powder is melted to obtain a liquid material, wherein the mixed raw material powder includes powder containing CaO, powder containing Al2O3, and optionally fluorine-containing powder;

[0043] S2. Cool and solidify the liquid material to room temperature and precipitate free calcium oxide microcrystals to obtain a solid material, thereby obtaining a desulfurizing agent for RH furnaces; the desulfurizing agent for RH furnaces includes calcium fluoroaluminate and / or calcium aluminate, wherein the calcium fluoroaluminate and / or the calcium aluminate contains the free calcium oxide microcrystals.

[0044] In the above technical solution provided in this application, a mixed raw material powder including CaO powder is melted and then cooled and solidified. During the cooling and solidification process, solid calcium fluoroaluminate and / or calcium aluminate can be formed, and free calcium oxide microcrystals can also precipitate during this process. Therefore, the obtained RH furnace desulfurizer contains highly active free calcium oxide microcrystals. Compared with directly using CaO raw material powder as a desulfurizer, these free calcium oxide microcrystals have a larger specific surface area, more lattice defects, and higher desulfurization reactivity, thus exhibiting higher desulfurization efficiency. Meanwhile, compared with the direct use of high-quality CaO raw material powder (such as a mass ratio exceeding 30%), which is prone to agglomeration and adhesion to the refractory wall of the RH furnace, causing non-uniform erosion, the free calcium oxide microcrystals of this application are uniformly dispersed in the calcium aluminate and / or calcium fluoroaluminate matrix as fine particles. Due to the support or fixation effect of the matrix, they are not prone to agglomeration and sintering. This can reduce or even avoid adhesion and non-uniform erosion to the refractory wall of the RH furnace, especially the impregnation tube, and reduce the occurrence of shutdown accidents.

[0045] It is understood that the "free calcium oxide" in this application refers to free calcium oxide, which precipitates out as a separate calcium oxide phase during the cooling and solidification process of liquid material.

[0046] It is understood that "room temperature" in this application refers to a temperature of -40℃ to 45℃, which can be selected as -20℃ to 40℃, further selected as 0℃ to 30℃, and even more selected as 10℃ to 25℃.

[0047] It is understood that the mass ratio of CaO-containing powder, Al2O3-containing powder, and fluorine-containing powder in the mixed raw material powder of step S1 can be designed based on the proportion of each component in the desired RH furnace desulfurizer.

[0048] In some embodiments, the particle size of the free calcium oxide microcrystals is greater than 0 μm and less than or equal to 500 μm, and can be selected from 10 μm to 200 μm. For example, the particle size of the free calcium oxide microcrystals can be 0.1 μm, 0.4 μm, 0.8 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 100 μm, 160 μm, 200 μm, 240 μm, 300 μm, 360 μm, 400 μm, 450 μm, 500 μm, or within any range of the above values. This allows the free calcium oxide microcrystals to have a large specific surface area, giving them high desulfurization reactivity, thus enabling the desulfurizing agent for RH furnaces to have a better desulfurization effect. At the same time, the free calcium oxide microcrystals are in the micrometer range, so even if some adhere to the refractory wall of the RH furnace, the impact on the refractory wall is minimal.

[0049] In some embodiments, the mass fraction of the free calcium oxide microcrystals in the RH furnace desulfurizer is 5% to 30%, optionally 10% to 30%. For example, the mass fraction of free calcium oxide microcrystals in the RH furnace desulfurizer can be 5%, 8%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, or within any range of the above values. This allows the RH furnace desulfurizer to have high desulfurization efficiency while minimizing the non-uniform erosion of the refractory wall of the RH furnace by free calcium oxide.

[0050] In some embodiments, the RH furnace desulfurizer comprises the following components by mass fraction: CaO 45%~65%, CaF2 0%~35%, Al2O3 15%~45%, SiO2 0%~8%, MgO≤8%, and impurities 0%~3%.

[0051] In some embodiments, the mass fraction w of CaO in the RH furnace desulfurizer satisfies the following condition: w = yx / 1.2; where x is the mass fraction of CaF2 in the RH furnace desulfurizer, x is 0%~35%, and y is 60%~75%. By ensuring that the mass fraction of CaO in the RH furnace desulfurizer satisfies the above condition, the mass fraction of free CaO microcrystals can be kept between 5% and 30%.

[0052] For example, x can be 0, 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or any of the above values; y can be 60%, 62%, 64%, 68%, 70%, 72%, 75%, or any of the above values.

[0053] It is understandable that the mass fraction of CaO in the desulfurizing agent for RH furnaces can be changed by adjusting the mass content of CaO powder in the mixed raw material powder.

[0054] In some embodiments, the particle size of the CaO-containing powder, the Al2O3-containing powder, and the fluorine-containing powder is independently greater than 0 mm and less than or equal to 3 mm, allowing for controlled mixing. For example, the particle size of each can be independently 150 μm, 300 μm, 500 μm, 1 mm, 3 mm, or within any range of these values. This ensures that the particle size of the three is substantially consistent, thereby facilitating the uniform distribution of the various phases in calcium fluoroaluminate and / or calcium aluminate.

[0055] In some embodiments, the CaO-containing powder includes lime powder and / or limestone powder, the Al2O3-containing powder includes alumina powder, and the fluorine-containing powder includes fluorite powder.

[0056] In some embodiments, the particle size of the crushed material is 3mm to 50mm, and may be 3mm to 20mm. For example, the particle size of the crushed material may be 3mm, 7mm, 10mm, 20mm, 30mm, 40mm, 50mm, or within any range of the above values.

[0057] In some embodiments, melting the mixed raw material powder includes:

[0058] The mixed raw material powder is heated to a target temperature, which is 1400℃~1550℃;

[0059] Keep warm at the target temperature for at least 15 minutes.

[0060] In some embodiments, gas stirring is used during the heating and / or holding process to homogenize the liquid material; the gas stirring uses nitrogen and / or argon.

[0061] In some embodiments, the cooling rate for solidifying the liquid material to 500°C is 100°C / min to 1000°C / min. For example, this cooling rate can be 100°C / min, 200°C / min, 300°C / min, 400°C / min, 500°C / min, 600°C / min, 700°C / min, 800°C / min, 900°C / min, 1000°C / min, or any range thereof. Controlling the cooling rate allows for the precipitation of an appropriate amount of free calcium oxide microcrystals, ensuring that the particle size of the precipitated free calcium oxide microcrystals is within the range described above, and also allows the precipitated free calcium oxide microcrystals to be uniformly dispersed in the calcium aluminate and / or calcium fluoroaluminate matrix.

[0062] It should be noted that the cooling rate of the liquid material from 500°C to 500°C is not limited, as long as it can be cooled from 500°C to room temperature.

[0063] In some embodiments, the preparation method may further include the following steps:

[0064] The solid material is crushed to obtain crushed material;

[0065] Optionally, after obtaining the crushed material, the process further includes: mixing lime particles into the crushed material to prepare the RH furnace desulfurizing agent, wherein the mass fraction of the lime particles in the RH furnace desulfurizing agent is 0-15%, and the chemical composition after mixing is controlled within the range of CaO 45%-65%, CaF2 0%-35%, Al2O3 15%-45%, SiO2 0%-8%, MgO≤8%, impurities 0%-3%, and the total mass fraction of free calcium oxide microcrystals and lime particles in the RH furnace desulfurizing agent is controlled within the range of 5%-30%.

[0066] For example, the mass fraction of lime particles in the desulfurizer for RH furnaces can be 0, 0.1%, 0.5%, 1%, 3%, 7%, 9%, 11%, 13%, 15%, or any range thereof. The total mass fraction of free calcium oxide microcrystals and lime particles in the desulfurizer for RH furnaces can be 5%, 8%, 10%, 15%, 20%, 25%, 30%, or any range thereof.

[0067] By controlling the mass fraction of lime particles in the desulfurizing agent used in RH furnaces to 0-15%, the desulfurization effect can be further improved, while the non-uniform erosion of the refractory wall of the RH furnace can be minimized, thus reducing or avoiding the occurrence of shutdown accidents.

[0068] In some embodiments, the crushing in the above steps can be carried out by the following method: the large solid material after cooling and solidification is manually crushed into smaller single pieces that can enter the jaw crusher, and then further fed into the jaw crusher to be crushed to the required particle size, such as 3mm~50mm.

[0069] Small pieces crushed by a jaw crusher can be fed into a ball mill or other grinding equipment to be ground into fine powder, and the particle size of the fine powder can be controlled as needed.

[0070] In some embodiments, the absolute value of the difference between the average particle size of the lime particles and the average particle size of the crushed material is ≤5mm.

[0071] In some embodiments, the lime particles have a particle size of 3 mm to 50 mm, and may be selected as 3 mm to 20 mm. For example, the particle size of the lime particles may be 3 mm, 7 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, or within any range of the above values.

[0072] Secondly, this application provides a desulfurizing agent for RH furnaces, which is prepared according to the preparation method of the first aspect of this application.

[0073] Thirdly, this application provides an application of the RH furnace desulfurizing agent of the second aspect of this application in RH furnace desulfurization.

[0074] The following are specific embodiments, which describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0075] Example 1

[0076] (1) Grind lime (CaO), fluorite (CaF2) and alumina (Al2O3, metallurgical grade) to 50 mesh (300μm) respectively, and then add them to the mixing bin at a mass ratio of 51:16:33 and mix them evenly to form a mixed raw material powder;

[0077] (2) Add the mixed raw material powder to the electric furnace, heat it to 1500℃ under argon stirring to melt it, and then keep it at the temperature for 20 minutes to obtain liquid material;

[0078] (3) Pour the liquid material into an iron container and cool it at a cooling rate of 650℃ / min to solidify it to room temperature. Then crush it into calcium fluoroaluminate crushed material with a particle size of 20mm~50mm and further crush it to obtain the desulfurizing agent for RH furnace.

[0079] Examples 2-5

[0080] Similar to the preparation method of Example 1, the main difference is that the mass ratio in step (1) is adjusted to change the mass ratio of each component in the obtained RH furnace desulfurizer, as shown in Table 1 below.

[0081] Example 6

[0082] Similar to the preparation method of Example 1, the main difference is that in step (3), lime particles with a particle size of 31mm~50mm are mixed into the crushed material, and further crushed to obtain RH furnace desulfurizer, and the mass fraction of lime particles in RH furnace desulfurizer is 15%.

[0083] Comparative Example 1

[0084] Similar to the preparation method of Example 1, the main difference is that steps (2) and (3) are omitted, alumina is omitted in step (1), and lime (CaO) and fluorite (CaF2) ground to 50 mesh are mixed in a mass ratio of 72:28 and then pressed to prepare RH furnace desulfurizer.

[0085] The desulfurizing agents for RH furnaces prepared in the above examples and comparative examples were subjected to relevant performance tests, and the test results are shown in Table 1 below. In the examples and comparative examples in the table, the remainder, except for the components listed in the table, are impurities. In Table 1, "average particle size" refers to the average particle size of the desulfurizing agent for RH furnaces; the mass fraction of each component in Examples 1 to 5 refers to the mass fraction of the corresponding component in the desulfurizing agent for RH furnaces.

[0086] The mass fraction of each component in Example 6 refers to the mass fraction of the corresponding component in the crushed material. The mass fractions of each component in the desulfurizing agent for RH furnace are as follows: CaO: 54%×(1-15%)+15%=52.8%, CaF2: 11%×(1-15%)=9.35%, Al2O3: 30%×(1-15%)=25.5%, SiO2: 1.6%×(1-15%)=1.36%, MgO: 2.1%×(1-15%)=1.79%, Free CaO microcrystals: 23%×(1-15%)=19.55%.

[0087] The test conditions or standards for each performance test item are as follows:

[0088] (1) Mass fraction: tested using an X-ray fluorescence spectrometer.

[0089] (2) Average particle size: tested using a scanning electron microscope.

[0090] Table 1

[0091]

[0092] As can be seen from Table 1 above, the sulfur capacity, a characteristic parameter of the desulfurizing agent for RH furnaces obtained by the three formulations in Examples 1-6, is significantly higher than that of the formulation in Comparative Example 1, thus the desulfurization effect is significantly improved (see also...). Figure 1 and Figure 2 The formulation in Comparative Example 1 frequently exhibits severe uneven erosion of RH-impregnated pipes during routine use, causing refractory material to fall off. (See below for details.) Figure 3 However, this phenomenon did not occur in the embodiments; the overall surface of the RH-impregnated tubes was uniform, and no refractory material fell off, as can be seen below. Figure 4 .

[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0094] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a desulfurizing agent for an RH furnace, characterized in that, include: The mixed raw material powder is melted to obtain a liquid material, wherein the mixed raw material powder includes powder containing CaO, powder containing Al2O3, and optionally fluorine-containing powder; The liquid material is cooled and solidified to room temperature, and free calcium oxide microcrystals are precipitated to obtain a solid material, which is used to prepare a desulfurizing agent for RH furnaces; the desulfurizing agent for RH furnaces includes calcium fluoroaluminate and / or calcium aluminate, and the calcium fluoroaluminate and / or the calcium aluminate contains the free calcium oxide microcrystals.

2. The preparation method according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The mass fraction of the free calcium oxide microcrystals in the desulfurizing agent for the RH furnace is 5%~30%, and can be selected as 10%~30%; (2) The particle size of the free calcium oxide microcrystals is greater than 0 μm and less than or equal to 500 μm.

3. The preparation method according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The mass fraction w of CaO in the RH furnace desulfurizing agent satisfies the following condition: w = yx / 1.2; Where x is the mass fraction of CaF2 in the RH furnace desulfurizer, x is 0%~35%, and y is 60%~75%; (2) The desulfurizing agent for the RH furnace includes the following components by mass fraction: CaO 45%~65%, CaF2 0%~35%, Al2O3 15%~45%, SiO2 0%~8%, MgO≤8%, and impurities 0%~3%.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The particle size of the CaO-containing powder, the Al2O3-containing powder, and the fluorine-containing powder is independently greater than 0 mm and less than or equal to 3 mm.

5. The preparation method according to any one of claims 1 to 3, characterized in that, The CaO-containing powder includes lime powder and / or limestone powder, the Al2O3-containing powder includes alumina powder, and the fluorine-containing powder includes fluorite powder.

6. The preparation method according to any one of claims 1 to 3, characterized in that, Melting the mixed raw material powder includes: The mixed raw material powder is heated to a target temperature, which is 1400℃~1550℃; Keep warm at the target temperature for at least 15 minutes; Optionally, gas stirring is used during the heating and / or heat preservation process to homogenize the liquid material; the gas stirring uses nitrogen and / or argon.

7. The preparation method according to any one of claims 1 to 3, characterized in that, The cooling rate for cooling and solidifying the liquid material to 500°C is 100°C / min to 1000°C / min.

8. The preparation method according to any one of claims 1 to 3, characterized in that, Also includes: The solid material is crushed to obtain crushed material; Optionally, after obtaining the crushed material, the process further includes: mixing lime particles into the crushed material to prepare the RH furnace desulfurizing agent, wherein the mass fraction of the lime particles in the RH furnace desulfurizing agent is 0-15%, and the total mass fraction of the free calcium oxide microcrystals and the lime particles in the RH furnace desulfurizing agent is 5%-30%. Optionally, the particle size of the crushed material is 3mm to 50mm, and optionally 3mm to 20mm; Optionally, the particle size of the lime particles is 3mm to 50mm, and can be 3mm to 20mm. Optionally, the absolute value of the difference between the average particle size of the lime particles and the average particle size of the crushed material is ≤5mm.

9. A desulfurizing agent for RH furnaces, characterized in that, Prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the desulfurizing agent for RH furnace as described in claim 9 in the desulfurization of RH furnace.

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