A method for controlling inclusions in smelting high-quality stainless steel from high-sulfur raw materials

Abstract

This application discloses a method for controlling inclusions in the smelting of high-quality stainless steel from high-sulfur raw materials, relating to the field of stainless steel smelting technology. This method employs a three-step synergistic process: AOD return to hot refining slag for pre-desulfurization, LTS deep slag removal followed by the addition of pre-melted calcium silicate synthetic slag, and then the addition of industrial silicon slag powder. Even with high-sulfur raw materials where the sulfur content at the AOD furnace input is 0.1%~0.3%, the sulfur reversion after LTS slag conditioning can still be controlled below 0.0005%. The total oxygen (TO) and sulfur content of the final product are stably maintained below 0.002%, with the sulfur content reaching as low as 0.0008%, significantly improving the corrosion resistance of the stainless steel. Efficient deoxidation and inclusion control are achieved through pre-melted synthetic slag formation, while industrial silicon slag further purifies the molten steel, inhibits oxygenation and sulfur reversion, and provides heat preservation, effectively avoiding surface quality defects in cold-rolled plates caused by hard inclusions.

Description

Technical Field

[0001] This application belongs to the field of stainless steel smelting technology, and in particular relates to a method for controlling inclusions in the smelting of high-quality stainless steel from high-sulfur raw materials. Background Technology

[0002] To adapt to the production development trend of reducing costs, improving efficiency, and enhancing quality in stainless steel, compared to the early high scrap steel ratio smelting, stainless steel smelting now extensively uses inexpensive furnace charge alloys, such as nickel pig iron, molten nickel-iron, nickel-iron, and recycled steel slag. These raw materials generally have a high sulfur content, with the sulfur content in the AOD (Alternating Oxygen Demand) furnace exceeding 0.1%. To achieve a high cold charge ratio and ensure AOD heat balance, high-carbon and high-silicon feedstocks are used, resulting in a long AOD smelting time, exceeding 90 minutes. Meanwhile, continuous casting uses high casting speeds to improve efficiency, inevitably compressing the ladle refining time.

[0003] With the increase in stainless steel production capacity, intensified market competition, and rising customer demands for product quality, the refining process is under increasing pressure, requiring the rapid completion of tasks such as temperature control, deoxidation and desulfurization, and inclusion removal. Conventional processes rely heavily on the addition of lime and fluorite for deoxidation and desulfurization, resulting in unstable slag system control, excessive hard inclusions, and fluctuations in the surface quality of cold-rolled steel sheets. Therefore, existing refining processes can no longer meet current production requirements for cost reduction, efficiency improvement, and quality enhancement. Summary of the Invention

[0004] To address some or all of the technical problems existing in the prior art, this application provides a method for controlling inclusions in the smelting of high-quality stainless steel from high-sulfur raw materials.

[0005] This application provides a method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials, comprising the following steps: Step S1: When the molten steel temperature is >1550℃ and the Si content is >0.3%, add molten or semi-molten return refining slag to the AOD furnace. The amount of return refining slag added is 65~150kg per ton of steel. After adding, stir for 5~10 minutes for pre-desulfurization, then pour off the slag, controlling the amount of slag left to be less than 30kg per ton of steel. After the AOD reduction period is completed and refining is finished, tap the steel, controlling the basicity of the tapped slag to be 1.8~2.2. Step S2: Remove the slag from the ladle until the amount of slag remaining is less than 5 kg per ton of steel, ensuring that the exposed surface area of ​​the molten steel is ≥60%; quickly add pre-melted calcium silicate synthetic slag, the amount added is controlled according to 90%~150% of the weight of the remaining slag, and the minimum amount added is 5 kg per ton of steel; after adding, use double-hole bottom blowing argon gas to strongly stir for 5~10 minutes to slag. Step S3: After slag formation is completed, add industrial silicon slag powder to the surface of the steel slag, with an addition amount of 10~150kg / furnace; after addition, stir with double-hole bottom-blowing argon gas.

[0006] Preferably, in step S1, the returned refining slag is AOD refining slag or ladle refining slag from the previous furnace or an adjacent furnace, and its mass percentage satisfies: Al2O3 / SiO2=0.3~5, CaO / Al2O3>1.2, (Fe2O3+FeO+Cr2O3+MnO)≤3%.

[0007] Preferably, the returned refining slag satisfies the following relationship: X≥400×[S]in+30, where X is the amount of returned refining slag added, in kg / t; and [S]in is the AOD sulfur content entering the furnace, in %.

[0008] Preferably, in step S1, the AOD reduction period involves at least one slag dumping, and the final slag amount does not exceed 30 kg per ton of steel.

[0009] Preferably, in step S2, the pre-melted calcium silicate synthesis slag meets the following performance requirements: melting point 1350~1450℃, melting rate 150~300s at 1500℃; its mass percentage chemical composition is: CaO: 50~56%, SiO2: 32~38%, Al2O3: ≤2%, MgO: 4~10%, (Fe2O3+FeO+MnO): ≤1.5%, TiO2: ≤0.8%, S: ≤0.05%, P: ≤0.05%, CaF2: 1~3%, C: ≤0.1%; its physical properties meet the following requirements: particle size 5~30mm accounts for more than 90% of the total, and dust content ≤5%.

[0010] Preferably, in step S2, after adding the synthetic slag, the flow rate of the bottom-blown argon gas in the dual-hole system is controlled to be 4~8 Nl / min per ton of steel; the basicity of the slag after slag conditioning is 1.2~1.7, and the phase ratio of wollastonite (CaO·SiO2) to dicalcium silicate (2CaO·SiO2) in the slag is (0.5~2.5):1.

[0011] Preferably, in step S3, the chemical composition of the industrial silicon slag powder by mass percentage is: Si: 10~30%, SiO2: 40~60%, T.Fe: ≤10%, Al2O3: ≤5%, CaO: 5~10%, MgO: 5~10%, C: ≤0.5%, S: ≤0.05%, P: ≤0.05%; its physical properties meet the following requirements: particle size 0.02~3mm, specific surface area 1~100m². 2 / kg.

[0012] Preferably, in step S3, the flow rate of the bottom-blown argon gas in the dual-hole system is controlled by a gradient: for the first 5 minutes after adding industrial silicon slag powder, the flow rate is 4~5 Nl / min per ton of steel; after 5 minutes, the flow rate is reduced to 2~4 Nl / min per ton of steel.

[0013] The inclusion control method for smelting high-quality stainless steel from high-sulfur raw materials in this application has the following advantages and positive effects: (1) The three-step synergistic process of pre-desulfurization of hot refining slag by AOD return, addition of pre-melted calcium silicate synthesis slag after LTS deep slag removal, and addition of industrial silicon slag powder can still control the sulfur return after LTS slag conditioning to below 0.0005% even under high sulfur raw material conditions with AOD sulfur content of 0.1%~0.3%. The total oxygen (TO) and sulfur content of the final product are stably maintained below 0.002%, and the sulfur content can be as low as 0.0008%, which significantly improves the corrosion resistance of stainless steel. At the same time, this method fully recycles and utilizes waste resources such as stainless steel slag and industrial silicon slag, greatly reduces the consumption of fresh slag materials such as lime and fluorite, and effectively reduces smelting costs.

[0014] (2) Desulfurization is not performed during the LTS / LF refining process, thus avoiding the problem of oxygenation in the molten steel caused by refining desulfurization; efficient deoxidation and inclusion control are achieved through pre-melted synthetic slag slag making; the molten steel is further purified, oxygenation and sulfur return are suppressed, and the temperature is maintained by industrial silicon slag, and the inclusions in the steel are controlled to be low-melting-point plastic SiO2-CaO-Al2O3-MgO, so that the proportion of plastic inclusions with a thickness direction of less than 3μm in the hot-rolled plate reaches more than 90%, effectively avoiding surface quality defects of cold-rolled plates caused by hard inclusions. In addition, this application adopts the method of re-slag making after removing the slag, which solves the problem of slag basicity and sulfur return fluctuation caused by the difficulty in controlling the amount of slag left in the prior art, ensuring the stability of slag composition and meeting the high-efficiency production requirements of short process and high drawing speed. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0016] The inclusion control method for smelting high-quality stainless steel from high-sulfur raw materials in this application is applicable to the smelting of high-grade nickel-based stainless steel such as 304, and the stainless steel produced can be used for products with high surface quality requirements such as 8K polishing materials.

[0017] The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials of this application includes the following steps: Step S1: When the molten steel temperature is >1550℃ and the Si content is >0.3%, molten or semi-molten return refining slag is added to the AOD furnace. The amount of return refining slag added is 65~150kg per ton of steel, and the following relationship is satisfied: X≥400×[S]in+30, where X is the amount of return refining slag added (kg / t); [S]in is the sulfur content of AOD entering the furnace (%). After adding, stir for 5~10 minutes for pre-desulfurization, then pour the slag, controlling the amount of slag remaining to be less than 30kg per ton of steel. After the AOD reduction period is completed and refining is finished, the steel is tapped, and the basicity of the tapped slag is controlled to be 1.8~2.2. The slag is poured at least once during the AOD reduction period, and the final amount of slag remaining does not exceed 30kg per ton of steel. By pre-desulfurizing with hot return slag, the desulfurization burden of AOD is reduced, the consumption of lime and fluorite is reduced, and low-cost and efficient desulfurization is achieved.

[0018] Among them, the returned refining slag is the AOD refining slag or ladle refining slag from the previous furnace or adjacent furnace, and its mass percentage satisfies: Al2O3 / SiO2=0.3~5, CaO / Al2O3>1.2, (Fe2O3+FeO+Cr2O3+MnO)≤3%.

[0019] Ensure that the returned slag has high desulfurization activity and low oxidizing properties to avoid oxygenation of molten steel and deterioration of inclusions.

[0020] Step S2: Remove the slag from the ladle until the amount of slag remaining is less than 5 kg per ton of steel, ensuring that the exposed surface area of ​​the molten steel is ≥60%; quickly add pre-melted calcium silicate synthetic slag, the amount of which is controlled at 90%~150% of the weight of the remaining slag, and the minimum amount of which is 5 kg per ton of steel; after adding, use double-hole bottom blowing argon gas to strongly stir for 5~10 minutes to slag.

[0021] Thoroughly remove high-sulfur residual slag to prevent subsequent sulfur reversion; quickly generate new slag to provide a stable slag system for deoxidation and inclusion control.

[0022] After adding the synthetic slag, the flow rate of the bottom-blown argon gas in the dual-hole system is controlled at 4~8 Nl / min per ton of steel; after slag conditioning, the slag basicity is 1.2~1.7, and the phase ratio of wollastonite (CaO·SiO2) to dicalcium silicate (2CaO·SiO2) in the slag is (0.5~2.5):1.

[0023] It achieves rapid homogenization of slag, obtains a stable slag system with low alkalinity and low oxidizing properties, effectively inhibits sulfur reversion and facilitates the formation of plastic inclusions.

[0024] Among them, the pre-melted calcium silicate synthesis slag is obtained by mixing silica with diopside, limestone, fluorite and quartz sand in an electric furnace in a certain proportion, and may include no more than 10% by weight of industrial silica slag powder. After melting at a high temperature of 1400~1550℃, the mixture is kept at that temperature for 30~60 minutes, rapidly cooled, and then crushed and dried.

[0025] The synthetic slag has uniform composition, fast melting speed, and good stability, which is conducive to precise on-site control.

[0026] The pre-melted calcium silicate synthesis slag meets the following performance requirements: melting point 1350~1450℃, melting rate 150~300s at 1500℃; its mass percentage chemical composition is: CaO: 50~56%, SiO2: 32~38%, Al2O3: ≤2%, MgO: 4~10%, (Fe2O3+FeO+MnO): ≤1.5%, TiO2: ≤0.8%, S: ≤0.05%, P: ≤0.05%, CaF2: 1~3%, C: ≤0.1%; its physical properties meet the following requirements: particle size 5~30mm accounts for more than 90% of the total, and dust content ≤5%.

[0027] Low melting point, fast melting rate, and low impurities reduce dust loss and facilitate on-site operation and stable control.

[0028] Step S3: After slag formation is completed, add industrial silicon slag powder to the surface of the steel slag, with an addition amount of 10~150kg / furnace; after addition, stir with double-hole bottom-blowing argon gas.

[0029] Silicon slag powder is used to deoxidize and purify molten steel, inhibit oxygenation and sulfur reversion, and at the same time assist in the modification of inclusions.

[0030] The flow rate of the bottom-blown argon gas in the dual-hole system is controlled by gradient: for the first 5 minutes after adding industrial silicon slag powder, the flow rate is 4~5 Nl / min per ton of steel; after 5 minutes, the flow rate is reduced to 2~4 Nl / min per ton of steel.

[0031] Strong stirring in the early stage promotes rapid dispersion and reaction of silicon slag powder, while weak stirring in the later stage helps to remove inclusions by floating and reducing the risk of slag entrapment.

[0032] Industrial silicon slag powder is produced from smelting slag or fine powder collected by bag filter dust collectors during industrial silicon production, through decarburization, crushing, and grinding. Its physical properties meet the following requirements: particle size range of 0.02~3mm, specific surface area of ​​1-100m². 2 / kg.

[0033] The chemical composition of industrial silicon slag powder by mass percentage is as follows: Si: 10~30%, SiO2: 40~60%, T.Fe: ≤10%, Al2O3: ≤5%, CaO: 5~10%, MgO: 5~10%, C: ≤0.5%, S: ≤0.05%, P: ≤0.05%.

[0034] The technical solution of this application is described below with reference to implementation examples, but the specific implementation of this application is not limited to the following embodiments.

[0035] Example 1 The process flow in this embodiment is 200t, AOD (Argon-Oxygen Decarburization Furnace) — LTS (Ladle Processing Station) — LF Ladle (Ladle Refining Furnace) — CCM (Continuous Casting Machine), and the specific steps are as follows: Step S1: When the temperature of the AOD molten steel is 1570℃ and the Si content is 2.3%, about 13t of AOD and ladle refining slag of this steel grade are returned and stirred for 10 minutes for pre-desulfurization. Then the slag is poured out, and the amount of slag left is controlled at 30kg per ton of steel. The slag is poured out twice during the AOD reduction period, and the final amount of slag left is 28kg per ton of steel. The basicity of the tapping slag is controlled at 2.15.

[0036] Step S2: Remove slag from the ladle until the amount of slag remaining is less than 5 kg per ton of steel, ensuring that the exposed surface area of ​​the molten steel is ≥60%; quickly add pre-melted calcium silicate synthetic slag, with the amount added controlled at 150% of the weight of the remaining slag; after adding, use double-hole bottom blowing argon gas for strong stirring for 10 minutes to slag, with the argon gas flow rate controlled at 8 Nl / min per ton of steel; after slag adjustment, the slag basicity is 1.63.

[0037] Step S3: After slag formation is completed, add 140 kg of industrial silicon slag powder to the surface of the steel slag; after adding, stir with double-hole bottom-blowing argon gas. The argon gas flow rate is 4 Nl / min per ton of steel for the first 5 minutes, and then reduced to 3 Nl / min per ton of steel after 5 minutes.

[0038] Afterwards, the composition and temperature can be finely adjusted through the LF furnace refining process, and finally continuous casting is carried out to obtain stainless steel billets.

[0039] Example 2 The process flow in this embodiment is 200t, AOD (Argon-Oxygen Decarburization Furnace) — LTS (Ladle Processing Station) — CCM (Continuous Casting Machine), and the specific steps are as follows: Step S1: When the AOD molten steel temperature is 1550℃ and the Si content is 1.5%, return approximately 18t of ultrapure ferritic steel AOD and ladle refining slag, stir for 10 minutes for pre-desulfurization, and then pour the slag, controlling the amount of slag left to be 25kg per ton of steel; pour the slag twice during the AOD reduction period, with the final amount of slag left being 20kg per ton of steel, and control the basicity of the tapping slag to be 1.96.

[0040] Step S2: Remove slag from the ladle until the amount of slag remaining is less than 5 kg per ton of steel, ensuring that the exposed surface area of ​​the molten steel is ≥60%; quickly add pre-melted calcium silicate synthetic slag, with the amount added controlled at 100% of the weight of the remaining slag; after adding, use double-hole bottom blowing argon gas for strong stirring for 8 minutes to slag, with the argon gas flow rate controlled at 5.5 Nl / min per ton of steel; after slag adjustment, the slag basicity is 1.52.

[0041] Step S3: After slag formation is completed, add 32 kg of industrial silicon slag powder to the surface of the steel slag; after adding, stir with double-hole bottom-blowing argon gas. The argon gas flow rate is 5 Nl / min per ton of steel for the first 5 minutes, and then reduced to 2 Nl / min per ton of steel after 5 minutes.

[0042] Then, continuous casting is carried out directly to obtain stainless steel billets.

[0043] Example 3 The process flow in this embodiment is 200t, AOD (Argon-Oxygen Decarburization Furnace) — LTS (Ladle Processing Station) — LF Ladle (Ladle Refining Furnace) — CCM (Continuous Casting Machine), and the specific steps are as follows: Step S1: When the temperature of the AOD molten steel is 1550℃ and the Si content is 1.5%, about 25t of AOD and ladle refining slag are returned and stirred for 10min for pre-desulfurization. Then the slag is poured out, and the amount of slag left is controlled at 24kg per ton of steel. The slag is poured out once during the AOD reduction period, and the final amount of slag left is 23kg per ton of steel. The basicity of the tapping slag is controlled at 1.81.

[0044] Step S2: Remove slag from the ladle until the amount of slag remaining is less than 5 kg per ton of steel, ensuring that the exposed surface area of ​​the molten steel is ≥60%; quickly add pre-melted calcium silicate synthetic slag, controlling the amount added to 80% of the weight of the remaining slag; after adding, use double-hole bottom blowing argon gas for strong stirring for 10 minutes to slag, with the argon gas flow rate controlled at 4 Nl / min per ton of steel; after slag adjustment, the slag basicity is 1.53.

[0045] Step S3: After slag formation is completed, add 45 kg of industrial silicon slag powder to the surface of the steel slag; after adding, stir with double-hole bottom-blowing argon gas. The argon gas flow rate is 5 Nl / min per ton of steel for the first 5 minutes, and then reduced to 2 Nl / min per ton of steel after 5 minutes.

[0046] The composition and temperature are then finely adjusted in the LF furnace refining process, and finally continuous casting is carried out to obtain stainless steel billets.

[0047] The specific composition of the pre-melted calcium silicate synthesis slag used in the above embodiments is shown in Table 1 below: Table 1

[0048] The specific parameters of the industrial silicon slag powder used in the above embodiments are shown in Table 2 below: Table 2

[0049] Comparative Example 1 The process flow for this comparative example is 200t: AOD (Argon-Oxygen Decarburization Furnace) — LTS (Ladle Processing Station) — LF (Ladle Refining Furnace) — CCM (Continuous Casting Machine). The specific steps are as follows: Step S1: AOD does not undergo pre-desulfurization. Instead, desulfurization is achieved by adding a large amount of lime and fluorite during the initial and adjustment periods, controlling the basicity of the tapping slag to 1.95.

[0050] Step S2: Remove the slag from the ladle until the amount of slag remaining is about 8 kg per ton of steel, and add lime and fluorite for further desulfurization; after slag adjustment, the slag basicity is 2.3.

[0051] The stainless steel billet is then refined in an LF furnace and finally continuously cast to obtain a stainless steel billet.

[0052] Comparative Example 2 The process flow for this comparative example is 200t: AOD (Argon-Oxygen Decarburization Furnace) — LTS (Ladle Processing Station) — LF (Ladle Refining Furnace) — CCM (Continuous Casting Machine). The specific steps are as follows: Step S1: AOD desulfurizes by adding a large amount of lime and fluorite during the early and adjustment periods, and controls the basicity of the slag at tapping to 2.13.

[0053] Step S2: Remove the slag from the ladle until the amount of slag remaining is about 8 kg per ton of steel, and add quartz sand to adjust the slag; after adjusting the slag, the basicity of the slag is 1.61.

[0054] The stainless steel billet is then refined in an LF furnace and finally continuously cast to obtain a stainless steel billet.

[0055] The comparison data of the effects of each embodiment and the comparative example are shown in Table 3 below: ; Note: Plastic inclusions refer to Class C silicate inclusions with a thickness of less than 3 μm in hot-rolled plates.

[0056] This application employs a three-step synergistic process: AOD return to hot refining slag for pre-desulfurization, LTS deep slag removal followed by the addition of pre-melted calcium silicate synthesis slag, and then the addition of industrial silicon slag powder. Even with high-sulfur raw materials (AOD inlet sulfur content of 0.1%~0.3%), the sulfur return after LTS slag conditioning can still be controlled below 0.0005%. The total oxygen (TO) and sulfur content of the final product are stably maintained below 0.002%, with the lowest sulfur content reaching 0.0008%, significantly improving the corrosion resistance of stainless steel. Simultaneously, this method fully recycles and utilizes waste resources such as stainless steel slag and industrial silicon slag, significantly reducing the consumption of fresh slag materials such as lime and fluorite, effectively lowering smelting costs.

[0057] This application avoids desulfurization during the LTS / LF refining process, thus preventing the oxygenation problem in the molten steel caused by refining desulfurization. It achieves efficient deoxidation and inclusion control through pre-melted synthetic slag formation, and further purifies the molten steel, suppresses oxygenation and sulfur reversion, and maintains heat preservation through industrial silicon slag. This controls inclusions in the steel to be low-melting-point plastic SiO2-CaO-Al2O3-MgO, ensuring that the proportion of plastic inclusions less than 3μm in the thickness direction of the hot-rolled plate reaches over 90%, effectively avoiding surface quality defects in cold-rolled plates caused by hard inclusions. Furthermore, this application employs a method of re-slag formation after removing all slag, solving the problem of slag basicity and sulfur reversion fluctuations caused by the difficulty in controlling the amount of slag left in existing technologies. This ensures stable slag composition and meets the high-efficiency production requirements of short-process, high-speed production.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials, characterized in that, The steps are as follows: Step S1: When the molten steel temperature is >1550℃ and the Si content is >0.3%, add molten or semi-molten return refining slag to the AOD furnace. The amount of return refining slag added is 65~150kg per ton of steel. After adding, stir for 5~10 minutes for pre-desulfurization, then pour off the slag, controlling the amount of slag left to be less than 30kg per ton of steel. After the AOD reduction period is completed and refining is finished, tap the steel, controlling the basicity of the tapped slag to be 1.8~2.

2. Step S2: Remove the slag from the ladle until the amount of slag remaining is less than 5 kg per ton of steel, ensuring that the exposed surface area of ​​the molten steel is ≥60%; quickly add pre-melted calcium silicate synthetic slag, the amount added is controlled according to 90%~150% of the weight of the remaining slag, and the minimum amount added is 5 kg per ton of steel; after adding, use double-hole bottom blowing argon gas to strongly stir for 5~10 minutes to slag. Step S3: After slag formation is completed, add industrial silicon slag powder to the surface of the steel slag, with an addition amount of 10~150kg / furnace; after addition, stir with double-hole bottom-blowing argon gas.

2. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S1, the returned refining slag is the AOD refining slag or ladle refining slag from the previous furnace or an adjacent furnace, and its mass percentage satisfies: Al2O3 / SiO2=0.3~5, CaO / Al2O3>1.2, (Fe2O3+FeO+Cr2O3+MnO)≤3%.

3. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S1, the returned refining slag satisfies the following relationship: X≥400×[S]in+30, where X is the amount of returned refining slag added, in kg / t; and [S]in is the sulfur content of AOD entering the furnace, in kg / t.

4. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S1, the slag is dumped at least once during the AOD reduction period, and the final amount of slag left does not exceed 30 kg per ton of steel.

5. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S2, the pre-melted calcium silicate synthesis slag meets the following performance requirements: melting point 1350~1450℃, melting rate 150~300s at 1500℃; Its chemical composition by mass percentage is as follows: CaO: 50~56%, SiO2: 32~38%, Al2O3: ≤2%, MgO: 4~10%, (Fe2O3+FeO+MnO): ≤1.5%, TiO2: ≤0.8%, S: ≤0.05%, P: ≤0.05%, CaF2: 1~3%, C: ≤0.1%; its physical properties meet the following requirements: particle size of 5~30mm accounts for more than 90% of the total, and dust content is ≤5%.

6. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S2, after adding the synthetic slag, the flow rate of the bottom-blown argon gas in the dual-hole system is controlled at 4~8 Nl / min per ton of steel; after slag conditioning, the slag basicity is 1.2~1.7, and the phase ratio of wollastonite (CaO·SiO2) to dicalcium silicate (2CaO·SiO2) in the slag is (0.5~2.5):

1.

7. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S3, the chemical composition of the industrial silicon slag powder by mass percentage is as follows: Si: 10~30%, SiO2: 40~60%, T.Fe: ≤10%, Al2O3: ≤5%, CaO: 5~10%, MgO: 5~10%, C: ≤0.5%, S: ≤0.05%, P: ≤0.05%; its physical properties meet the following requirements: particle size 0.02~3mm, specific surface area 1~100m². 2 / kg.

8. The method for controlling inclusions in the smelting of high-grade stainless steel from high-sulfur raw materials according to claim 1, characterized in that, In step S3, the flow rate of the bottom-blown argon gas in the dual-hole system is controlled by gradient: for the first 5 minutes after adding industrial silicon slag powder, the flow rate is 4~5 Nl / min per ton of steel; after 5 minutes, the flow rate is reduced to 2~4 Nl / min per ton of steel.

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