A composite operation method applied to LF production process to realize rapid desulfurization

Abstract

This invention provides a composite operation method for rapid desulfurization in LF production processes, relating to the field of steelmaking technology. The method includes the following steps: S1, after molten steel is introduced, argon is blown in. Based on the pre-argon conditions, a calculated amount of aluminum granules is added from a high-level silo for centralized deoxidation, and active lime is added for slag formation; S2, electrodes are energized. Before the end of the first energization cycle, 10-15 kg of aluminum granules are vibrated in. The effect of top slag modification is assessed by observing the color of the flue gas. If the flue gas is not grayish-white or higher, deoxidized aluminum granules are added after the energization ends; S3, after the energization ends, strong argon blowing and stirring desulfurization are performed, and finally, samples are taken for precise evaluation. This invention not only reduces the refining cycle and the amount of deoxidized aluminum granules used, but also significantly reduces the labor intensity of workers and the risk of safety accidents throughout the entire chain.

Description

Technical Field

[0001] This invention relates to the field of steelmaking technology, and more particularly to a composite operation method for achieving rapid desulfurization in the LF production process. Background Technology

[0002] The LF furnace, a crucial ladle refining equipment in the steelmaking process, possesses functions such as electric arc heating, argon gas stirring and mixing, slag formation, refining, and desulfurization, making it one of the core processes for producing high-quality steel. Currently, in the traditional LF furnace slag formation and desulfurization process, aluminum wire is typically fed into the molten steel via a wire feeder for deoxidation. However, this process is extremely slow, hindering the rapid aggregation, growth, and flotation of Al2O3 inclusions. Furthermore, during electrode energization, traditional operations involve adding aluminum particles to the top slag in multiple batches for modification. This results in the aluminum particles easily melting and burning instantly at the high temperatures (10000~15000K) generated by the electric arc, causing ineffective oxidation and loss of the deoxidizer, significantly increasing production costs. In addition, evaluating the top slag modification effect in traditional processes requires frequent operation of the primary ladle screen by workers. Furthermore, after stopping the power supply and blowing argon, a special tool must be used to collect liquid slag samples for visual inspection. These cumbersome procedures not only increase the labor intensity of workers but also severely delay the refining cycle.

[0003] Therefore, how to achieve efficient deoxidation and rapid modification of top slag, reduce ineffective burn-off of deoxidizer, shorten the LF treatment cycle, and reduce the labor intensity of workers while ensuring the quality of molten steel are the urgent technical problems to be solved in the current LF furnace refining process. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a composite operation method for rapid desulfurization in LF production processes. This invention achieves efficient and rapid desulfurization in LF furnaces by rapidly deoxidizing the furnace through a single aluminum feed at the furnace entrance, vibrating the material before power-on termination, and using the color of the furnace gas and dust to predict the quality improvement effect and guide aluminum replenishment.

[0005] To achieve the above objectives, this invention provides a composite operation method for rapid desulfurization applied to the LF production process, comprising the following steps: S1. After the molten steel is transferred into the LF furnace, argon blowing and stirring are started. According to the pre-argon conditions, the calculated amount of aluminum particles are added from the high-level silo at one time to carry out centralized deoxidation and upgrading of the molten steel and top slag. At the same time, active lime is added to form slag to create the initial conditions for desulfurization. S2. The electrode is energized to perform submerged arc operation. Two minutes before the end of one energization, 10-15 kg of aluminum granules are shaken into the top slag from the high-level silo. The color change of the furnace gas and dust after the aluminum granules are added is observed by the naked eye to comprehensively evaluate the top slag modification effect. Based on the color of the dust, it is calculated whether the slag modification aluminum granules need to be added after the energization ends and the amount of aluminum granules to be added. S3. After power-on, if the S2 assessment requires additional addition, add deoxidized aluminum particles; if no additional addition is required, directly perform strong argon blowing and stirring for desulfurization. After argon blowing, use a special tool to dip into the liquid slag sample to accurately assess the effect of the first modification.

[0006] Furthermore, in step S1, the formula for calculating the amount of aluminum added is: Aluminum addition (kg) = Oxygen value before argon / 100ppm × 30 + ((Upper limit of Als in steel grade specification - Als before argon) + (Sulfur content before argon - 0.020%)) × 10000 × 20.

[0007] Furthermore, in S1, the amount of active lime added is controlled according to the temperature of the molten steel entering the station and the air permeability of the ladle.

[0008] Furthermore, when the molten steel temperature is not less than 1550℃ and the air permeability is good, the amount of active lime added should satisfy the following formula, and it should be added all at once from the high-level silo: Added amount of active lime (kg) = 800 + (pre-argon sulfur content - 0.020%) × 10000 × 200.

[0009] Furthermore, when the molten steel temperature is less than 1550℃ and the air permeability is good, only half the amount of active lime added to S1 is added when the molten steel temperature is not less than 1550℃ and the air permeability is good. The remaining half of the active lime is added during the energization of the S2 electrode.

[0010] Furthermore, in S2, during the period when the electrode is energized, the aluminum particles are not added in batches to the top slag.

[0011] Furthermore, in S2, by observing the color change process of the flue gas from black to gray to white, it corresponds to the degree of slag modification from black slag to ordinary reducing slag to white slag.

[0012] Furthermore, if the color of the flue gas is not observed to be above grayish-white, it is determined that the top slag modification effect has not met the standard, and 20-40 kg of deoxidized aluminum particles should be added after the power is turned on.

[0013] Furthermore, in S3, the stirring time of the forced argon stirring satisfies the following calculation formula: Stirring time (min) = 6 + (pre-argon sulfur content - 0.020%) × 10000 × 2.

[0014] By adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1. This invention provides a composite operation method for rapid desulfurization in LF production processes. By injecting aluminum granules from a high-level silo at the time of entry into the plant for centralized deoxidation, it replaces the traditional slow aluminum wire feeding process, allowing Al2O3 inclusions to quickly collide, grow, and float. Simultaneously, by vibrating the material at a high level and observing the color of the furnace gas and dust before the power is turned off, the effect of top slag modification can be quickly predicted non-contactly. This reduces the cumbersome operation steps in traditional processes, such as power outages, large-scale argon blowing, and taking liquid slag samples, effectively shortening the refining cycle, better matching the furnace and machine for refining and continuous casting, achieving efficient steel supply, and further improving the casting machine's capacity.

[0015] 2. The present invention provides a composite operation method for rapid desulfurization in LF production process, which reduces the ineffective oxidation and burn-off of deoxidizer, significantly saves alloy production costs, and eliminates the need for batch feeding of aluminum particles during electrode energization, or only feeds them in small batches under special circumstances. This fundamentally avoids the probability of aluminum particles being burned and oxidized by the high temperature of the electric arc, reduces the waste of ineffective deoxidation, and can successfully reduce the amount of deoxidized aluminum particles used under the same production conditions.

[0016] 3. The present invention provides a composite operation method for achieving rapid desulfurization in the LF production process. Through the system optimization of the composite operation method, on the one hand, workers no longer need to frequently click on the primary machine screen, which greatly reduces the need for frequent manual computer operation; on the other hand, the smoke and dust color feedback mechanism reduces the operation of frequently manually dipping liquid slag samples, reduces the incidence of operational accidents, and improves the safety of on-site operations. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a composite operation method for achieving rapid desulfurization in the LF production process, as described in this invention. Figure 2 This is a flowchart illustrating the determination of the amount of active lime added in a composite operation method for achieving rapid desulfurization in LF production process, as described in this invention. Figure 3 This is a flowchart illustrating the color change determination of furnace gas and flue dust after the addition of aluminum granules in a composite operation method for rapid desulfurization in LF production process, as described in this invention. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, S, operations, devices, components, and / or combinations thereof.

[0022] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and S illustrated in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples listed and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0023] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0024] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0025] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0026] like Figures 1 to 3 As shown, this invention provides a composite operation method for achieving rapid desulfurization in LF production processes, comprising the following steps: S1. After the molten steel is transferred into the LF furnace, argon blowing and stirring are started. According to the pre-argon conditions, the calculated amount of aluminum particles are added from the high-level silo at one time to carry out centralized deoxidation and upgrading of the molten steel and top slag. At the same time, active lime is added to form slag to create the initial conditions for desulfurization. S2. The electrode is energized to perform submerged arc operation. Two minutes before the end of one energization, 10-15 kg of aluminum granules are shaken into the top slag from the high-level silo. The color change of the furnace gas and dust after the aluminum granules are added is observed by the naked eye to comprehensively evaluate the top slag modification effect. Based on the color of the dust, it is calculated whether the slag modification aluminum granules need to be added after the energization ends and the amount of aluminum granules to be added. S3. After power-on, if the S2 assessment requires additional addition, add deoxidized aluminum particles; if no additional addition is required, directly perform strong argon blowing and stirring for desulfurization. After argon blowing, use a special tool to dip into the liquid slag sample to accurately assess the effect of the first modification.

[0027] Furthermore, in step S1, the formula for calculating the amount of aluminum added is: Aluminum addition (kg) = Oxygen value before argon / 100ppm × 30 + ((Upper limit of Als in steel grade specification - Als before argon) + (Sulfur content before argon - 0.020%)) × 10000 × 20.

[0028] Furthermore, in S1, the amount of active lime added is controlled according to the temperature of the molten steel entering the station and the air permeability of the ladle.

[0029] Furthermore, when the molten steel temperature is not less than 1550℃ and the air permeability is good, the amount of active lime added should satisfy the following formula, and it should be added all at once from the high-level silo: Added amount of active lime (kg) = 800 + (pre-argon sulfur content - 0.020%) × 10000 × 200.

[0030] Furthermore, when the molten steel temperature is less than 1550℃ and the air permeability is good, only half the amount of active lime added to S1 is added when the molten steel temperature is not less than 1550℃ and the air permeability is good. The remaining half of the active lime is added during the energization of the S2 electrode.

[0031] Furthermore, in S2, during the period when the electrode is energized, the aluminum particles are not added in batches to the top slag.

[0032] Furthermore, in S2, by observing the color change process of the flue gas from black to gray to white, it corresponds to the degree of slag modification from black slag to ordinary reducing slag to white slag.

[0033] Furthermore, if the color of the flue gas is not observed to be above grayish-white, it is determined that the top slag modification effect has not met the standard, and 20-40 kg of deoxidized aluminum particles should be added after the power is turned on.

[0034] Furthermore, in S3, the stirring time of the forced argon stirring satisfies the following calculation formula: Stirring time (min) = 6 + (pre-argon sulfur content - 0.020%) × 10000 × 2.

[0035] Example 1 This embodiment provides a composite operation method for achieving rapid desulfurization in the LF production process, which is suitable for ideal working conditions where the molten steel inlet temperature is ≥1550℃ and the ladle has good air permeability.

[0036] S1. Centralized deoxidation and preliminary slag formation of molten steel After the molten steel is transferred into the LF furnace, argon blowing and stirring are immediately initiated. Based on the pre-argon detection conditions, a calculated amount of aluminum granules is added from the high-level silo in one go to achieve concentrated and rapid deoxidation and upgrading of the molten steel and top slag. At the same time, active lime is added to form slag, creating initial conditions for subsequent desulfurization.

[0037] The calculation of the amount of aluminum added shall be strictly carried out according to the following formula: Aluminum addition (kg) = (Oxygen value before argon / 100ppm) × 30 + ((Upper limit of Als in steel grade specification - Als before argon) + (Sulfur content before argon - 0.020%)) × 1000 × 20.

[0038] The amount of quicklime added is controlled based on the temperature of the molten steel entering the station and the permeability of the ladle. Since the operating conditions in this embodiment are a molten steel temperature of not less than 1550℃ and good permeability, the amount of quicklime added satisfies the following formula and is added in one go from the high-level silo: Added amount of active lime (kg) = 800 + (pre-argon sulfur content - 0.020%) × 10000 × 200.

[0039] S2. Judgment of the effect of electrode energization and top ash modification The electrodes are energized, and a submerged arc operation is performed to ensure heating efficiency and stability. During this step, aluminum granules are not added in batches to the top slag while the electrodes are energized to avoid ineffective oxidation and burn-off of the aluminum granules under the high temperature of the electric arc.

[0040] Two minutes before the end of each power-on cycle, 10-15 kg of aluminum granules are vibrated and added to the top slag from the high-level hopper. At this time, the operator observes the color change of the flue gas after the aluminum granules are added. The flue gas color will change from black to gray to white, corresponding to the degree of slag modification: black slag → ordinary reducing slag → white slag. Black slag corresponds to insufficient deoxidation, gray to ordinary reducing slag, and white to ideal reducing slag. Based on the observed flue gas color, the operator comprehensively evaluates the top slag modification effect. If the observed flue gas color is not grayish-white or higher, i.e., still black or dark gray, the top slag modification effect is deemed unsatisfactory, and the operator calculates the need to add 20-40 kg of aluminum granules after the power-on cycle ends. If the color has reached grayish-white, no additional addition is required.

[0041] S3, Desulfurization Operation and Effect Evaluation After power-on, perform the following operations based on the results of step S2: If the assessment requires additional addition, then add the calculated amount of deoxidized aluminum granules.

[0042] If the assessment indicates that no additional addition is needed, then proceed directly with strong argon blowing and stirring for desulfurization.

[0043] The duration of strong argon stirring is not fixed, but rather follows the calculation formula below: Stirring time (min) = 6 + (pre-argon sulfur content - 0.020%) × 10000 × 2.

[0044] After the strong argon stirring is completed, a special tool is used to dip into the liquid slag sample to accurately evaluate the effect of the first modification and ensure that the quality of the molten steel meets the requirements of subsequent processes.

[0045] Through the above steps, this embodiment achieves rapid, efficient, and low-cost desulfurization under ideal operating conditions.

[0046] Example 2 This embodiment provides another composite operation method for achieving rapid desulfurization in the LF production process, which is basically the same as that in Embodiment 1, except that it is used in a working condition where the molten steel inlet temperature is <1550℃ and the air permeability is good.

[0047] S1, Centralized deoxidation and partial slag formation of molten steel After the molten steel is transferred into the LF furnace, argon stirring begins. The calculation of the amount of aluminum added is exactly the same as in Example 1, still using the following formula to add it all at once from the high-level silo.

[0048] The addition of active lime is different. Because the temperature of the molten steel is less than 1550℃, only half the standard amount is added to S1. The standard amount is calculated using the following formula: Added amount of active lime (kg) = 800 + (pre-argon sulfur content - 0.020%) × 10000 × 200.

[0049] Therefore, the actual amount of active lime added to S1 is half of the calculated result.

[0050] S2. Judgment of electrode energization and residual slag formation and upgrading effect The electrodes are energized to initiate submerged arc operation. During energization, aluminum granules are not added to the top slag in batches. Simultaneously, the remaining half of the active lime not added in S1 is added during electrode energization to complete the entire slag-forming process.

[0051] Two minutes before the end of a power-on cycle, 10-15 kg of aluminum granules are vibrated and added to the top slag from the high-level silo. The effect of the top slag modification is evaluated by observing the color of the furnace gas and dust, and it is then determined whether 20-40 kg of deoxidized aluminum granules need to be added after the power-on cycle ends.

[0052] S3, Desulfurization Operation and Effect Evaluation This step is exactly the same as in Example 1. After the power is turned on, aluminum particles are selectively added according to the evaluation results of S2. Then, strong argon stirring desulfurization is carried out according to the formula: stirring time (min) = 6 + (pre-argon sulfur content - 0.020%) × 10000 × 2. Finally, a liquid slag sample is dipped for accurate evaluation.

[0053] This embodiment demonstrates that the method of the present invention has good adaptability and operability under different inlet temperatures. By flexibly adjusting the timing of lime addition, it ensures that good slag-forming and desulfurization effects can be obtained even at low temperature molten steel.

[0054] Comparative Example This comparative example provides a traditional LF furnace slag formation and desulfurization operation method for comparison with the embodiments of the present invention.

[0055] S1, Traditional Deoxygenation Operation After the molten steel is transferred into the LF furnace, argon stirring begins. Instead of adding aluminum granules all at once, aluminum wire is slowly fed into the molten steel via a wire feeder, with the feeding amount typically ranging from 200 to 500 meters based on experience. The process of wire feeding, aluminum wire melting, and reaction with oxygen in the steel to form Al2O3 is slow, usually lasting more than 5 minutes, which is not conducive to the rapid aggregation and floating of inclusions.

[0056] S2. Evaluation of the effects of traditional slag formation and upgrading The electrodes are energized, and aluminum granules are fed into the top slag from the high-level silo in multiple batches and small quantities for slag removal and oxygen modification. Because the temperature at the center of the electric arc is extremely high when energized, a significant portion of the fed aluminum granules melts and burns instantly at this high temperature, resulting in ineffective oxidation of the deoxidizer and wasted costs. Furthermore, workers need to frequently operate the computer to feed the granules, leading to high labor intensity.

[0057] To assess the effectiveness of the top slag modification, the power supply must be stopped, and after argon blowing and stirring, workers must use a special tool to dip into the furnace to collect a liquid slag sample. The sample color is then visually inspected to determine its quality. This step is cumbersome and time-consuming, and for highly oxidizing top slag, it needs to be repeated multiple times, severely impacting the processing cycle and increasing the labor intensity and safety risks for workers.

[0058] S3, Traditional Desulfurization Operation After multiple assessments and supplementary operations, the top ash was deemed to have passed the upgrading process, and then forced argon stirring desulfurization was carried out. The stirring time is usually based on fixed experience values ​​or the operator's personal judgment, lacking dynamic and precise control for different sulfur contents. The entire LF treatment cycle is long, deoxidizer consumption is high, and the workload for workers is heavy.

[0059] The comparison between the above embodiments and comparative examples shows that the operation method provided by the present invention has significant advantages in terms of deoxidizer consumption, treatment cycle, worker labor intensity and operation safety, and achieves stable and rapid desulfurization effect.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite operation method for achieving rapid desulfurization in LF production process, characterized in that, Includes the following steps: S1. After the molten steel is transferred into the LF furnace, argon blowing and stirring are started. According to the pre-argon conditions, the calculated amount of aluminum particles are added from the high-level silo at one time to carry out centralized deoxidation and upgrading of the molten steel and top slag. At the same time, active lime is added to form slag to create the initial conditions for desulfurization. S2. The electrode is energized to perform submerged arc operation. Two minutes before the end of one energization, 10-15 kg of aluminum granules are shaken into the top slag from the high-level silo. The color change of the furnace gas and dust after the aluminum granules are added is observed by the naked eye to comprehensively evaluate the top slag modification effect. Based on the color of the dust, it is calculated whether the slag modification aluminum granules need to be added after the energization ends and the amount of aluminum granules to be added. S3. After power-on, if the S2 assessment requires additional addition, add deoxidized aluminum particles; if no additional addition is required, directly perform strong argon blowing and stirring for desulfurization. After argon blowing, use a special tool to dip into the liquid slag sample to accurately assess the effect of the first modification.

2. The composite operation method for achieving rapid desulfurization in LF production process according to claim 1, characterized in that, In S1, the formula for calculating the amount of aluminum added is: Aluminum addition (kg) = Oxygen value before argon / 100ppm × 30 + ((Upper limit of Als in steel grade specification - Als before argon) + (Sulfur content before argon - 0.020%)) × 10000 × 20.

3. The composite operation method for achieving rapid desulfurization in LF production process according to claim 1, characterized in that, In S1, the amount of active lime added is controlled according to the temperature of the molten steel entering the station and the air permeability of the ladle.

4. The composite operation method for achieving rapid desulfurization in LF production process according to claim 3, characterized in that, When the molten steel temperature is not less than 1550℃ and the air permeability is good, the amount of active lime added should meet the following formula, and should be added in one go from the high-level silo: Added amount of active lime (kg) = 800 + (pre-argon sulfur content - 0.020%) × 10000 × 200.

5. The composite operation method for achieving rapid desulfurization in LF production process according to claim 4, characterized in that, When the molten steel temperature is less than 1550℃ and the air permeability is good, only half the amount of active lime added to S1 is added when the molten steel temperature is not less than 1550℃ and the air permeability is good. The remaining half of the active lime is added during the energization of electrode S2.

6. The composite operation method for achieving rapid desulfurization in LF production process according to claim 1, characterized in that, In step S2, during the period when the electrode is energized, the aluminum particles are not added in batches to the top slag.

7. The composite operation method for achieving rapid desulfurization in LF production process according to claim 1, characterized in that, In S2, by observing the color change process of the flue gas from black to gray to white, it corresponds to the degree of slag modification from black slag to ordinary reducing slag to white slag.

8. The composite operation method for achieving rapid desulfurization in LF production process according to claim 7, characterized in that, If the color of the flue gas is not grayish-white or higher, it is determined that the top slag modification effect is not up to standard. After the power is turned on, add 20-40 kg of deoxidized aluminum particles.

9. The composite operation method for achieving rapid desulfurization in LF production process according to claim 1, characterized in that, In step S3, the stirring time for forced argon stirring satisfies the following calculation formula: Stirring time (min) = 6 + (pre-argon sulfur content - 0.020%) × 10000 × 2.

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