A smelting method for sulfur-containing low-silicon steel

Abstract

This invention discloses a smelting method for sulfur-containing low-silicon steel. The production process involves electric furnace smelting, LF refining, vacuum degassing, and continuous casting. By utilizing rational process and slag design based on raw materials, smelting, and continuous casting, the silicon content of the steel is stably controlled at ≤0.08% and the sulfur content at 0.015-0.030%, allowing for continuous casting of more than 15 furnaces.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and particularly relates to a smelting method of sulfur-containing low-silicon steel. Background Art

[0002] Silicon is an oxidizing element that promotes grain boundary oxidation at the surface of the carburized layer in gear steel. High silicon content significantly degrades carburizing performance, reducing fatigue strength and pitting resistance. Its harmfulness is 10 times greater than that of Mn and Cr, so a low Si content is recommended. MnCr gear steel requires a silicon content of ≤0.12%, but exceeding this limit can easily occur during production. Furthermore, sulfur-containing steel is prone to nozzle blockage, creating significant production challenges for this type of product.

[0003] During the silicon steelmaking process, various raw and auxiliary materials contain a certain amount of sulfur, which increases the uncertainty of controlling the sulfur content of the finished product. Current sulfur control technology for producing silicon steel with a finished sulfur content of less than 15 ppm primarily relies on RH desulfurization. While current KR desulfurization rates are generally high, typically reducing the sulfur content of molten iron to below 15 ppm or even lower, to ensure effective desulfurization, slag is typically removed as thoroughly as possible, but ladle cleaning and handling procedures are insufficiently considered. Because molten iron desulfurization slag primarily consists of CaO and a small amount of CaF2, it has a high melting point and easily adheres to the ladle mouth, walls, and bottom. The sulfur content of this slag is typically greater than 2.5% or even higher. If it falls into the converter during the iron addition process, it can significantly increase the sulfur content of the converter's molten iron. In addition to sulfur introduced into the converter by the molten iron and slag, the scrap steel added to the converter also contains a certain amount of sulfur. Due to the relatively high amount of scrap added, this is also a major factor contributing to the sulfur increase in the converter's molten steel. Silicon steel undergoes deep decarburization (RH) after being tapped from a converter. The large amount of alloying added to silicon steel increases the amount of sulfur introduced into the alloy, a major factor in the resulfurization of the molten steel. RH treatment allows for direct continuous casting, a relatively smooth process with minimal resulfurization. Therefore, if the sulfur content after RH alloying can be reduced to below the target sulfur content, the sulfur content of the finished product can be guaranteed to meet the control target.

[0004] Therefore, many manufacturers carry out desulfurization treatment in the RH process when smelting ultra-low sulfur silicon steel. For example, in patent CN110042200A, Anshan Iron and Steel also adopts KR deep desulfurization and converter controlled sulfur return to reduce the sulfur content level of RH incoming molten steel when smelting ultra-low sulfur steel. However, due to improper control methods, the RH incoming sulfur content exceeds 15ppm. Then, after RH alloying, 2.5-6.0kg / t of CaO-CaF2 series desulfurizer is added to desulfurize the molten steel to achieve the control target of less than 15ppm sulfur content in the finished product. Shougang Qian'an patent CN102634642A discloses a RH desulfurization technology method for non-oriented silicon steel, which adds 4-6kg / t of desulfurizer to the S vacuum tank for desulfurization after RH deoxidation and alloying. Patent CN103266198B discloses a RH powder spray desulfurization technology solution, which achieves a better desulfurization effect by spraying fine powder desulfurizer. Ultra-low sulfur steel can be smelted through RH vacuum desulfurization, but there are also many shortcomings. First, the desulfurizers used in RH vacuum furnace desulfurization are mostly CaO-CaF2 slag systems. The CaF2 component is highly toxic to humans and very corrosive to refractory materials. Silicon steel can generally be continuously cast for more than 12 furnaces. If a large amount of CaO-CaF2 desulfurizer is used in each furnace, it will cause great corrosion damage to RH refractory materials. RH powder spray desulfurization technology significantly improves the desulfurization effect due to the small particle size of the desulfurizer sprayed in with a spray gun. Calcium aluminate desulfurization slag systems can be used to solve the problem of refractory corrosion. However, calcium aluminate slag systems can easily cause spray gun sticking, which greatly increases the maintenance cost of the vacuum furnace spray gun, and frequent maintenance will also affect production efficiency. Chinese patent application CN115558734A discloses a low-carbon, low-silicon, ultra-low-sulfur steel and its smelting method, belonging to the field of steel smelting technology. The method comprises: pre-treating molten iron with desulfurization to obtain pre-treated molten iron; smelting the pre-treated molten iron in a converter, followed by oxygen-retaining tapping to obtain molten steel; refining the molten steel with VD to obtain decarbonized molten steel; and refining the decarbonized molten steel with LF to obtain refined molten steel, completing the smelting process. Chinese patent CN109468426B discloses a method for desulfurizing and desiliconizing molten iron in a molten iron tank and smelting low-phosphorus and sulfur steel with low slag in a converter, belonging to the field of steelmaking technology. The process steps are as follows: the KR method is used to perform pre-treatment desulfurization of molten iron in the molten iron tank, and the sulfur of the molten iron is removed to below 0.002% in the molten iron tank; the KR method is used to perform pre-treatment desiliconization of molten iron in the molten iron tank, and the silicon is removed to 0.20%-0.40%. At the end, the molten iron temperature is controlled to be above 1250°C before leaving the station; the low-silicon molten iron after desulfurization and desiliconization is placed in a converter for decarburization, desiliconization and dephosphorization, and the low-silicon molten iron is added to the converter for decarburization, desiliconization and dephosphorization. The smelting is carried out by a top-bottom combined blowing process of top-blowing oxygen and bottom-blowing argon. At the end of smelting, the weight percentage of C in the molten steel is 0.05%-0.30%, and the end point [P]+[S] is ≤200ppm. The converter is tapped and the molten steel is discharged into a ladle for direct continuous casting or casting after RH refining.Chinese patent application CN107955856A discloses a method for refining and desulfurizing low-silicon steel. The method includes slag adjustment, slag formation, heating, and desulfurization steps. The low-silicon steel to be refined has Si ≤ 0.03% and S 0.020-0.030%. First, aluminum powder is added to the ladle to adjust the slag composition and reduce the oxidizing properties of the slag. Then, lime and fluorite are added to form the slag. When the molten steel temperature reaches above 1600°C, calcium carbide is added. Its weak reducing properties remove oxygen from the refining slag, thereby promoting the desulfurization reaction and reducing the sulfur content of the molten steel. Furthermore, due to its weak reducing properties, calcium carbide does not reduce the silicon in the slag, thus preventing an increase in the silicon content of the molten steel. The oxidation product of calcium carbide is carbon monoxide, which improves the submerged arc efficiency during the refining process.

[0005] Therefore, in order to control the sulfur and silicon content of the finished product, it is necessary to develop a low-cost, efficient low-sulfur silicon steel smelting method. Summary of the Invention

[0006] The object of the present invention is to provide a smelting method for sulfur-containing low-silicon steel. Starting from the raw materials, smelting and continuous casting processes, by adopting reasonable process and slag design, the silicon content of the steel is stably controlled at ≤0.08%, the sulfur content is 0.015-0.030%, and continuous casting of more than 15 furnaces can be maintained.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A smelting method for sulfur-containing low-silicon steel, comprising the following steps:

[0009] Electric furnace smelting: The proportion of molten iron in the furnace is ≥40%. During the tapping process, 7-9 kg / t of low-titanium synthetic slag and 2.5-4 kg / t of lime are added. Pure Al ingots are used for deoxidation, and metallic manganese and low-carbon ferrochrome are used for alloying. Any silicon-containing materials are prohibited.

[0010] LF refining: After refining, the Al content is controlled within the range of 0.030-0.050%, and the amount of aluminum-reduced silicon is reduced. Calcium carbide and carbon powder are added in the early stage of refining for deoxidation and desulfurization. The amount of calcium carbide added is 0.5-1.4 kg / t steel, and the sulfur content is controlled to be ≤0.010%. During the refining process, Al wire can be added in small amounts twice according to the Al content. During the refining process, the Al content is kept within the range of 0.030-0.050%, and the Al content of steel tapping is controlled at 0.045-0.055%. High-basicity slag is produced, and the basicity of the LF tapping binary furnace slag is controlled to be ≥6. Before LF tapping, high-calcium wire is added at 1.2-1.6 m / t steel, and the time interval between feeding the aluminum wire and the calcium wire is greater than 3 minutes.

[0011] Vacuum degassing: vacuum degree is less than 67Pa and maintained for ≥12 minutes, argon flow rate is 50-70NL / min; after breaking the air, feed 0.7-1.3m / t steel into the sulfur line, argon flow rate is 10-20NL / min, and soft argon blowing time is not less than 20 minutes;

[0012] Continuous casting: Double-layer tundish covering agent is used for continuous casting, with low-titanium alkaline tundish covering agent used for the lower layer and low-titanium hollow particle tundish covering agent used for the upper layer. Electromagnetic stirring is adopted; the tundish superheat is 20-35℃, the straightening temperature is ≥920℃, and the billet is slowly cooled after landing for ≥24 hours.

[0013] Preferably, the composition of the low-titanium synthetic slag is SiO2≤2%, CaO: 45-55%, MgO: 5-8%, Al2O3: 30-40%, TiO2≤0.04%.

[0014] Preferably, during electric furnace smelting, the amount of Al ingot added is 1.2-1.6 kg / t steel.

[0015] Preferably, in LF refining, the basicity of LF steel-making binary slag is controlled at 8-10, and the slag components are CaO: 45-55%, SiO2: 3-7%, Al2O3: 35-45%, and MgO: 5-7%.

[0016] Preferably, during continuous casting, the crystallizer electromagnetic stirring current is 150-250A, the frequency is 3-4Hz, and the end electromagnetic stirring current is 250-300A, the frequency is 12-14Hz.

[0017] Preferably, during continuous casting, the water volume of the roller is 34-36 NL / min, and the water volume of the crystallizer is 140-150m 3 / h, specific water volume 0.28~0.30L / kg.

[0018] Preferably, during continuous casting, the casting speed of a 260mm×300mm billet is 0.52 to 0.57m / min, and the casting speed of a 180mm×220mm billet is 1.05 to 1.10m / min.

[0019] In the present invention, the Si content is stably controlled at ≤0.08%. The MnS inclusions of the finished product after rolling produced by the method are dispersed, and the A fine inclusions are all below level 1.5.

[0020] By adopting the smelting method of the present invention, more than 15 furnaces can be continuously cast while ensuring that the silicon content is stably controlled at ≤0.08% and the sulfur content is 0.015-0.030%.

[0021] According to a preferred embodiment of the present invention, a smelting method of sulfur-containing low-silicon steel comprises the following steps:

[0022] Production process: electric furnace smelting, LF refining, vacuum degassing, and continuous casting.

[0023] Electric furnace: The proportion of molten iron entering the furnace is ≥40%. During the tapping process, 7-9 kg / t steel of low-titanium synthetic slag and 2.5-4 kg / t steel of lime are added. The composition of the low-titanium synthetic slag is SiO2≤2%, CaO: 45-55%, MgO: 5-8%, Al2O3: 30-40%, TiO2≤0.04%. Pure Al ingots are used for deoxidation. The amount of Al ingot added is 1.2-1.6 kg / t steel. Metallic manganese and low-carbon ferrochromium are used for alloying. It is prohibited to add any silicon-containing materials.

[0024] LF refining: After refining, the Al content is controlled within the range of 0.030-0.050%, and the amount of silicon reduced by aluminum is reduced. Calcium carbide and carbon powder are added in the early stages of refining for deoxidation and desulfurization. The calcium carbide addition rate is 0.5-1.4 kg / t steel, and the sulfur content is controlled to ≤ 0.010%. Al wire can be added in small amounts twice during the refining process depending on the Al content. The Al content is maintained within the range of 0.030-0.050% during the refining process, and the Al content at tapping is controlled at 0.045-0.055%. High-basicity slag is produced. The basicity of the LF tapping binary slag is controlled to be ≥6, preferably 8-10. The slag composition is CaO: 45-55%, SiO2: 3-7%, Al2O3: 35-45%, and MgO: 5-7%. Before LF tapping, 1.2-1.6 m3 / t steel of high-calcium wire is added. The interval between feeding the aluminum wire and the calcium wire is greater than 3 minutes.

[0025] Vacuum degassing: vacuum degree is less than 67Pa and maintained for ≥12 minutes, argon flow rate is 50-70NL / min; after breaking the air, feed 0.7-1.3m / t of sulfur line, argon flow rate is 10-20NL / min, and soft argon blowing time is not less than 20 minutes.

[0026] Continuous casting: Double-layer tundish covering agent is used for continuous casting, low-titanium alkaline tundish covering agent is used for the lower layer, low-titanium hollow particle tundish covering agent is used for the upper layer, electromagnetic stirring is adopted, the crystallizer electromagnetic stirring current is 150-250A, frequency is 3-4HZ, the end electromagnetic stirring current is 250-300A, frequency is 12-14HZ; the water volume of the foot roller is 34-36NL / min, and the water volume of the crystallizer is 140-150m 3 / h, specific water volume 0.28~0.30L / kg; tundish superheat 20~35℃, 260mm×300mm square billet pulling speed 0.52~0.57m / min, 180mm×220mm square billet pulling speed 1.05~1.10m / min, straightening temperature ≥920℃, slow cooling of billet after landing ≥24 hours.

[0027] Compared with the prior art, the technical solution of the present invention has the following excellent effects:

[0028] 1. The present invention effectively controls the Si content by rationally selecting raw materials, and rationally designing and controlling the smelting process, the Al content in the refining process, and the slag system. The Si content can be stably controlled at ≤ 0.08%, thereby eliminating the adverse effects of silicon on the grain boundaries in the infiltration layer.

[0029] 2. The present invention effectively solves the nozzle nodule agglomeration problem and MnS precipitation and aggregation problem of sulfur-containing steel by rationally designing the aluminum and calcium wire addition process, the soft blowing process after the sulfur feeding line, and the continuous casting strong cooling process, thereby ensuring stable and smooth production and achieving continuous casting of more than 15 furnaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a macroscopic microstructure diagram of the ingot obtained in Example 1;

[0031] Figure 2 This is a low-magnification microstructure diagram of the ingot obtained in Example 2. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0033] Example 1:

[0034] Electric furnace smelting: The proportion of molten iron in the furnace is 67.4%. During the tapping process, 8.0kg / t of low-titanium synthetic slag and 3.5kg / t of lime are added. Pure Al ingots are used for deoxidation, and the amount of Al ingot added is 1.4kg / t of steel. Metal manganese and low-carbon ferrochromium are used for alloying. Any silicon-containing materials are prohibited.

[0035] LF refining: The final Al content is 0.42%. Calcium carbide and carbon powder are added in the early stages of refining for deoxidation and desulfurization. The calcium carbide addition rate is 1.0 kg / t steel, and the sulfur content is 0.005%. Al wire can be added in small amounts twice during the refining process depending on the Al content. The Al content is maintained within the range of 0.040-0.050% during the refining process. The Al content of the tapped steel is 0.053%, and high-basicity slag is produced. The basicity of the LF tapped binary furnace slag is 8.97. High-calcium wire is added at 1.4 m / t steel before LF tapping, with a 5-minute interval between the aluminum wire and the calcium wire.

[0036] Vacuum degassing: vacuum degree is less than 67Pa and maintained for 12 minutes, argon flow rate is 70NL / min; after breaking the air, feed the sulfur line 1.0m / t, argon flow rate is 14NL / min, and soft argon blowing time is 26 minutes.

[0037] Continuous casting: Double-layer tundish covering agent is used for continuous casting, low titanium alkaline tundish covering agent is used for the lower layer, low titanium hollow particle tundish covering agent is used for the upper layer, electromagnetic stirring is adopted, the crystallizer electromagnetic stirring current is 150A, frequency is 3HZ, the end electromagnetic stirring current is 300A, frequency is 12HZ; the water volume of the foot roller is 35NL / min, and the water volume of the crystallizer is 145m 3 / h, specific water content 0.29L / kg; tundish superheat 32℃, 260mm×300mm square billet pulling speed 0.55m / min, pulling and straightening temperature 942℃, billet landing and slow cooling 30 hours.

[0038] Macrostructure of ingot Figure 1 shown.

[0039] Example 2

[0040] Electric furnace smelting: The proportion of molten iron in the furnace is 55.4%. During the tapping process, 7.5kg / t of low-titanium synthetic slag and 4kg / t of lime are added. Pure Al ingots are used for deoxidation, and the amount of Al ingot added is 1.2kg / t of steel. Metal manganese and low-carbon ferrochromium are used for alloying. Any silicon-containing materials are prohibited.

[0041] LF refining: The Al content after refining is 0.038%. Calcium carbide and carbon powder are added in the early stage of refining for deoxidation and desulfurization. The amount of calcium carbide added is 0.6g / t steel, and the sulfur content is controlled to be ≤0.007%. During the refining process, Al wire can be added in small amounts in two times according to the Al content. The Al content is kept within the range of 0.035-0.045% during the refining process. The Al content of steel tapping is 0.047%, and high basicity slag is produced. The basicity of LF tapping binary furnace slag is 9.42. Before LF tapping, high calcium wire is added at 1.2m / t steel. The time interval between feeding aluminum wire and calcium wire is 7 minutes.

[0042] Vacuum degassing: vacuum degree is less than 67Pa and maintained for 13 minutes, argon flow rate is 65NL / min; after breaking the air, feed the sulfur line 0.8m / t, argon flow rate is 13NL / min, and soft argon blowing time is 28 minutes.

[0043] Continuous casting: Double-layer tundish covering agent is used for continuous casting. The lower layer uses low-titanium alkaline tundish covering agent, and the upper layer uses low-titanium hollow particle tundish covering agent. Electromagnetic stirring is adopted. The crystallizer electromagnetic stirring current is 200A, the frequency is 3.5HZ, and the end electromagnetic stirring current is 300A, the frequency is 13HZ. The water volume of the foot roller is 34NL / min, and the water volume of the crystallizer is 143m 3 / h, specific water volume 0.28L / kg; tundish superheat 28℃, 260mm×300mm square billet pulling speed 0.53m / min, pulling and straightening temperature 935℃, billet landing and slow cooling 34 hours.

[0044] Macrostructure of ingot Figure 2 shown.

[0045] Example 3:

[0046] Electric furnace smelting: The proportion of molten iron in the furnace is 72%. During the tapping process, 8.5kg / t steel of low-titanium synthetic slag and 3.2kg / t steel of lime are added. Pure Al ingots are used for deoxidation, and the amount of Al ingot added is 1.6kg / t steel. Metal manganese and low-carbon ferrochromium are used for alloying. Any silicon-containing materials are prohibited.

[0047] LF refining: Refining is done within the Al content range of 0.050%. Calcium carbide and carbon powder are added in the early stage of refining for deoxidation and desulfurization. The amount of calcium carbide added is 1.2kg / t steel, and the sulfur content is controlled to be ≤0.004%. During the refining process, Al wire can be added in small amounts twice according to the Al content. During the refining process, the Al content is kept within the range of 0.045-0.050%. The Al content of steel tapping is 0.050%. High basicity slag is produced. The basicity of LF tapping binary furnace slag is controlled at 9.86. Before LF tapping, high calcium wire is added at 1.6m / t steel. The time interval between feeding aluminum wire and calcium wire is 6 minutes.

[0048] Vacuum degassing: vacuum degree is less than 67Pa and maintained for 13 minutes, argon flow rate is 60NL / min; after breaking the air, feed the sulfur line 1.1m / t, argon flow rate is 15NL / min, and soft argon blowing time is 24 minutes.

[0049] Continuous casting: Double-layer tundish covering agent is used for continuous casting. The lower layer uses low-titanium alkaline tundish covering agent, and the upper layer uses low-titanium hollow particle tundish covering agent. Electromagnetic stirring is adopted. The crystallizer electromagnetic stirring current is 200A, the frequency is 3HZ, and the end electromagnetic stirring current is 250A, the frequency is 13HZ. The water volume of the foot roller is 36NL / min, and the water volume of the crystallizer is 148m 3 / h, specific water volume 0.30L / kg; tundish superheat 24℃, 260mm×300mm square billet pulling speed 0.56m / min, pulling and straightening temperature 940℃, billet landing and slow cooling for 28 hours.

[0050] The Si, S, and Al contents of the finished products of Examples 1 to 3 are shown in Table 1. Si is ≤ 0.08%. The surface quality of the resulting ingots is good, the low-power quality of the ingots is good, the center porosity is 1.0, and there are no other defects, such as Figure 1-2 As shown in Table 2, the MnS inclusions of the finished product after rolling produced by this method are dispersed, and the A fine inclusions are all below level 1.5. The level of non-metallic inclusions is shown in Table 2.

[0051] Table 1 Si, S, Al content of finished products

[0052] Example Si content, % S content, % Al content, % 1 0.071 0.0246 0.0261 2 0.062 0.0203 0.0302 3 0.078 0.0188 0.0342

[0053] Table 2 Non-metallic inclusions

[0054]

[0055] The process parameters (such as temperature, time, etc.) of the present invention can realize the method by taking upper and lower limits and interval values, and the embodiments are not listed here one by one.

[0056] Any content not described in detail in the present invention can be based on conventional technical knowledge in the art.

[0057] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and are intended to be encompassed by the claims of the present invention.

Claims

1. A method for smelting sulfur-containing low-silicon steel, the smelting method comprising the following steps: Electric furnace smelting: The proportion of molten iron in the furnace is ≥40%, and 7-9 kg / t of low-titanium synthetic slag and 2.5-4 kg / t of lime are added during the tapping process. Pure Al ingots are used for deoxidation, and metallic manganese and low-carbon ferrochrome are used for alloying. Any silicon-containing materials are prohibited. The composition of the low-titanium synthetic slag is SiO2 ≤ 2%, CaO: 45-55%, MgO: 5-8%, Al2O3: 30-40%, and TiO2 ≤ 0.04%. LF refining: After refining, the Al content is controlled within the range of 0.030-0.050%, and the amount of aluminum-reduced silicon is reduced. Calcium carbide and carbon powder are added in the early stage of refining for deoxidation and desulfurization. The amount of calcium carbide added is 0.5-1.4 kg / t steel, and the sulfur content is controlled to be ≤0.010%. During the refining process, Al wire is added in small amounts twice according to the Al content. During the refining process, the Al content is kept within the range of 0.030-0.050%, and the Al content of steel tapping is controlled at 0.045-0.055%. High-basicity slag is produced, and the basicity of the LF tapping binary furnace slag is controlled to be ≥6. Before LF tapping, high-calcium wire is added at 1.2-1.6 m / t steel. The time interval between feeding the aluminum wire and the calcium wire is greater than 3 minutes. Vacuum degassing: vacuum degree is less than 67Pa and maintained for ≥12 minutes, argon flow rate is 50-70NL / min; after breaking the air, feed 0.7-1.3m / t steel into the sulfur line, argon flow rate is 10-20NL / min, and soft argon blowing time is not less than 20 minutes; Continuous casting: Double-layer tundish covering agent is used for continuous casting, with low-titanium alkaline tundish covering agent used for the lower layer and low-titanium hollow particle tundish covering agent used for the upper layer. Electromagnetic stirring is adopted; the tundish superheat is 20-35℃, the straightening temperature is ≥920℃, and the casting is slowly cooled after landing for ≥24 hours; during continuous casting, the water volume of the full roller is 34-36NL / min, and the water volume of the crystallizer is 140-150m 3 / h, specific water volume 0.28~0.30L / kg; The silicon content of the steel is stably controlled at ≤0.08%, and the sulfur content is 0.015-0.030%.

2. The method for smelting sulfur-containing low-silicon steel according to claim 1, characterized in that: In electric furnace smelting, the amount of Al ingot added is 1.2 to 1.6 kg per ton of steel.

3. The method for smelting sulfur-containing low-silicon steel according to claim 1, characterized in that: During LF refining, the basicity of LF steel-making binary slag is controlled at 8-10, and the slag composition is CaO: 45-55%, SiO2: 3-7%, Al2O3: 35-45%, and MgO: 5-7%.

4. The method for smelting sulfur-containing low-silicon steel according to claim 1, characterized in that: During continuous casting, the crystallizer electromagnetic stirring current is 150-250A, the frequency is 3-4Hz, and the end electromagnetic stirring current is 250-300A, the frequency is 12-14Hz.

5. The method for smelting sulfur-containing low-silicon steel according to claim 1, characterized in that: During continuous casting, the pulling speed of 260mm×300mm square billet is 0.52~0.57m / min, and the pulling speed of 180mm×220mm square billet is 1.05~1.10m / min.

6. The method for smelting sulfur-containing low-silicon steel according to claim 1, characterized in that: The ingot produced by this smelting method has dispersed MnS inclusions in the finished product after rolling, and the A fine inclusions are all below level 1.

5.

7. The method for smelting sulfur-containing low-silicon steel according to claim 1, characterized in that: Under the conditions of low sulfur and silicon, more than 15 furnaces were cast continuously.

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