Method for smelting low-phosphorus steel

Abstract

This application provides a method for smelting low-phosphorus steel, comprising: adding steel raw materials and converter slag to a converter for converter smelting to obtain converter steel, wherein the temperature of the converter steel is 1620℃-1650℃; after transferring the converter steel to a vacuum furnace, adding a dephosphorizing agent to the converter steel; under the condition of top lance oxygen blowing treatment in the vacuum furnace, circulating the converter steel according to a first preset parameter to obtain first steel; subjecting the first steel to deoxidation treatment and heating treatment to obtain second steel; circulating the second steel according to a second preset parameter to obtain low-phosphorus steel; wherein the second preset parameter is less than the first preset parameter, and both the first and second preset parameters include vacuum degree, inert gas flow rate, and steel circulation volume. This application can reduce the converter smelting cycle and slag consumption, improve the converter operating rate, and enhance the oxidizability of steel slag, thereby improving the dephosphorization effect and achieving a further reduction in the phosphorus content of the steel.

Description

Technical Field

[0001] This application relates to the field of iron and steel metallurgy technology, and in particular to a method for smelting low-phosphorus steel. Background Technology

[0002] Ultra-low carbon steel, as the main raw material for producing deep-drawing and ultra-deep-drawing cold-rolled substrates, is widely used in industries such as automobiles, home appliances, and precision welded pipes. However, phosphorus in steel significantly reduces its toughness, increases its cold brittleness, and affects the uniformity of its local microstructure, thereby impacting the mechanical properties of the steel.

[0003] In related technologies, the converter double slag method is generally used to smelt low-phosphorus steel to reduce the phosphorus content in ultra-low carbon steel. However, the converter double slag method will significantly increase the converter smelting cycle and slag consumption, reduce the converter operating rate, and the dephosphorization effect is limited, making it difficult to further reduce the phosphorus content of molten steel. Summary of the Invention

[0004] This application provides a method for smelting low-phosphorus steel to solve the problems in related technologies where the converter double-slag method significantly increases the converter smelting cycle and slag consumption, reduces the converter operating rate, and has limited dephosphorization effect, making it difficult to further reduce the phosphorus content of molten steel.

[0005] This application provides a method for smelting low-phosphorus steel, comprising the following steps: Steel raw materials and converter slag are added to a converter for converter smelting to obtain converter steel. The temperature of the converter steel is 1620℃-1650℃. The molten steel from the converter is transferred to the vacuum furnace, and a dephosphorizing agent is added to the molten steel after the transfer. Under the condition of oxygen blowing treatment by top lance in vacuum furnace, the molten steel in converter is circulated according to the first preset parameters to obtain the first molten steel; The first molten steel is subjected to deoxidation and heating treatment to obtain the second molten steel; The second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel; wherein the second preset parameters are less than the first preset parameters, and both the first and second preset parameters include vacuum degree, inert gas flow rate and molten steel circulation volume.

[0006] According to an embodiment of this application, the vacuum value in the first preset parameter is ≤67Pa.

[0007] According to an embodiment of this application, the vacuum degree value in the second preset parameter is 600Pa-800Pa.

[0008] According to an embodiment of this application, the inert gas flow rate in the first preset parameter is 170 m³ / h. 3 / h-180m 3 / h.

[0009] According to an embodiment of this application, the inert gas flow rate in the second preset parameter is 120m³. 3 / h-130m 3 / h.

[0010] According to an embodiment of this application, the molten steel circulation rate in the first preset parameter is 190t / min-195t / min.

[0011] According to an embodiment of this application, the molten steel circulation rate in the second preset parameter is 150t / min-160t / min.

[0012] According to an embodiment of this application, the phosphorus content in the converter molten steel is ≤0.012wt%.

[0013] According to an embodiment of this application, the phosphorus content in the first molten steel is ≤0.010wt%.

[0014] According to an embodiment of this application, the phosphorus content in low-phosphorus molten steel is ≤0.008wt%.

[0015] According to an embodiment of this application, the top-gun oxygen flow rate for top-gun oxygen blowing treatment is 1800 Nm³. 3 / h-2000Nm 3 / h.

[0016] According to an embodiment of this application, the raw materials for molten steel include molten iron and scrap steel. The raw materials for molten steel and converter slag are added to a converter for converter smelting to obtain converter steel, comprising: Under the condition of controlling the iron-to-metal ratio at 20%-25%, the molten steel raw material and converter slag are added to the converter for converter smelting to obtain converter steel.

[0017] According to the embodiments of this application, the phosphorus content in the molten iron is 0.08wt%-0.10wt%.

[0018] According to embodiments of this application, the dephosphorizing agent comprises lime and iron ore, wherein the mass ratio of lime to iron ore ranges from 2:1 to 5.4:1.

[0019] According to an embodiment of this application, under the condition of top-lance oxygen blowing treatment in a vacuum furnace, the molten steel in the converter is circulated according to a first preset parameter to obtain a first molten steel, including: Under the condition that the total iron content in the ladle slag is controlled to be 15%-18% by controlling the amount of iron ore used, and oxygen blowing treatment is performed on the top lance of the vacuum furnace, the molten steel in the converter is circulated according to the first preset parameters to obtain the first molten steel.

[0020] According to the embodiments of this application, the amount of lime added is 1.8 kg / t-2.7 kg / t, and the amount of iron ore added is 0.5 kg / t-0.9 kg / t.

[0021] According to an embodiment of this application, a second molten steel is obtained by deoxidizing and heating the first molten steel, including: Aluminum blocks are added to the first molten steel for deoxidation and heating treatment to obtain the second molten steel.

[0022] According to an embodiment of this application, the temperature rise range of the heating process is 15°C-25°C.

[0023] According to the embodiments of this application, the amount of aluminum block added is 0.5 kg / t to 0.9 kg / t.

[0024] In the smelting process of low-phosphorus steel, by controlling the temperature of the converter steel at 1620℃-1650℃, the dephosphorization capacity of the converter can be improved by utilizing the principle of low-temperature dephosphorization. On this basis, after transferring the converter steel to a vacuum furnace, adding a dephosphorizing agent to the converter steel, and performing top-lance oxygen blowing treatment in the vacuum furnace, the converter steel is circulated according to the first preset parameters to obtain the first molten steel. This not only reduces the converter smelting cycle and slag consumption and improves the converter operating rate by performing secondary desulfurization in the vacuum furnace, but also enhances the circulation kinetic energy of the molten steel by utilizing the vacuum furnace steel circulation and improves the oxidizability of the steel slag by utilizing top-lance oxygen blowing treatment, thereby improving the dephosphorization effect and achieving a further reduction in the phosphorus content of the molten steel.

[0025] Furthermore, by deoxidizing and heating the first molten steel, a second molten steel is obtained; then, the second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel. The second preset parameters are less than the first preset parameters. Both the first and second preset parameters include vacuum degree, inert gas flow rate, and molten steel circulation volume. After the molten steel composition is deoxidized, the circulation kinetic energy of the molten steel can be reduced by decreasing the vacuum degree, circulating argon gas flow rate, and molten steel circulation volume. This avoids the phenomenon of molten steel re-phosphorus due to excessive disturbance of steel slag in the molten steel with reduced oxidizability, and helps to further improve the dephosphorization effect. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] Figure 1 This is a flowchart of the smelting method for low-phosphorus molten steel provided in this application.

[0028] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0029] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] Ultra-low carbon steel, as the main raw material for producing deep-drawing and ultra-deep-drawing cold-rolled substrates, is widely used in industries such as automobiles, home appliances, and precision welded pipes. However, phosphorus in steel significantly reduces its toughness, increases its cold brittleness, and affects the uniformity of its local microstructure, thereby impacting the mechanical properties of the steel.

[0033] In related technologies, the converter double slag method is generally used to smelt low-phosphorus steel to reduce the phosphorus content in ultra-low carbon steel. However, the converter double slag method will significantly increase the converter smelting cycle and slag consumption, reduce the converter operating rate, and the dephosphorization effect is limited, making it difficult to further reduce the phosphorus content of molten steel.

[0034] In view of the above problems, this application provides a method for smelting low-phosphorus steel, which can reduce the converter smelting cycle and slag consumption, improve the converter operating rate, and enhance the oxidizability of steel slag, thereby improving the dephosphorization effect and achieving a further reduction in the phosphorus content of molten steel.

[0035] This application provides a method for smelting low-phosphorus steel. Please refer to [link to relevant documentation]. Figure 1 It includes the following steps: S100: Steel raw materials and converter slag are added to a converter for converter smelting to obtain converter steel. The temperature of the converter steel is 1620℃-1650℃. S200: Transfer the molten steel from the converter to the vacuum furnace, and add a dephosphorizing agent to the molten steel after the transfer. S300: Under the condition of oxygen blowing treatment by top lance in vacuum furnace, the molten steel in converter is circulated according to the first preset parameters to obtain the first molten steel; S400: The first molten steel is deoxidized and heated to obtain the second molten steel; S500: The second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel; wherein, the second preset parameters are less than the first preset parameters, and both the first and second preset parameters include vacuum degree, inert gas flow rate and molten steel circulation volume.

[0036] In the smelting process of low-phosphorus steel, by controlling the temperature of the converter steel at 1620℃-1650℃, the dephosphorization capacity of the converter can be improved by utilizing the principle of low-temperature dephosphorization. On this basis, after transferring the converter steel to a vacuum furnace, adding a dephosphorizing agent to the converter steel, and performing top-lance oxygen blowing treatment in the vacuum furnace, the converter steel is circulated according to the first preset parameters to obtain the first molten steel. This not only reduces the converter smelting cycle and slag consumption and improves the converter operating rate by performing secondary desulfurization in the vacuum furnace, but also enhances the circulation kinetic energy of the molten steel by utilizing the vacuum furnace steel circulation and improves the oxidizability of the steel slag by utilizing top-lance oxygen blowing treatment, thereby improving the dephosphorization effect and achieving a further reduction in the phosphorus content of the molten steel.

[0037] Furthermore, by deoxidizing and heating the first molten steel, a second molten steel is obtained; then, the second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel. The second preset parameters are less than the first preset parameters. Both the first and second preset parameters include vacuum degree, inert gas flow rate, and molten steel circulation volume. After the molten steel composition is deoxidized, the circulation kinetic energy of the molten steel can be reduced by decreasing the vacuum degree, circulating argon gas flow rate, and molten steel circulation volume. This avoids the phenomenon of molten steel re-phosphorus due to excessive disturbance of steel slag in the molten steel with reduced oxidizability, and helps to further improve the dephosphorization effect.

[0038] The S100 process is as follows: molten steel and converter slag are added to a converter for smelting to obtain molten steel. The temperature of the molten steel is 1620℃-1650℃.

[0039] In practical applications, by controlling the temperature of the molten steel in the converter to 1620℃-1650℃, which is 20-30℃ lower than the traditional process, the dephosphorization capacity of the converter can be improved by utilizing the principle of low-temperature dephosphorization.

[0040] In some embodiments, the phosphorus content in the converter molten steel is ≤0.012wt%.

[0041] In this embodiment, by setting the phosphorus content in the converter molten steel to ≤0.012wt%, the subsequent dephosphorization process can be carried out on the basis of a lower phosphorus content, thereby effectively achieving further dephosphorization effect.

[0042] In some embodiments, the raw materials for molten steel include molten iron and scrap steel. The raw materials for molten steel and converter slag are added to a converter for converter smelting to obtain converter steel, including: Under the condition of controlling the iron-to-metal ratio at 20%-25%, the molten steel raw material and converter slag are added to the converter for converter smelting to obtain converter steel.

[0043] In practical applications, by adding steel raw materials and converter slag to the converter for converter smelting under the condition of controlling the iron ratio at 20%-25%, converter steel can be obtained. By controlling the iron ratio, the amount of scrap steel added can be increased, thereby reducing the amount of phosphorus introduced during the converter smelting stage, which helps to obtain low-phosphorus steel that meets the predetermined requirements.

[0044] In some embodiments, the phosphorus content in the molten iron is 0.08wt%-0.10wt%.

[0045] In this embodiment, by limiting the phosphorus content in molten iron, the total amount of phosphorus entering the system can be controlled from the source, thereby reducing the dephosphorization load and improving the overall dephosphorization efficiency and stability.

[0046] The S200 steps are as follows: the molten steel from the converter is transferred to the vacuum furnace, and a dephosphorizing agent is added to the molten steel after the transfer.

[0047] In practical applications, molten steel from the converter can be transferred to a vacuum furnace, and a dephosphorizing agent can be added to the molten steel after the transfer. This allows for secondary desulfurization in the vacuum furnace, reducing the converter smelting cycle and slag consumption, and improving the converter operating rate.

[0048] In some embodiments, the dephosphorizing agent comprises lime and iron ore, wherein the mass ratio of lime to iron ore ranges from 2:1 to 5.4:1.

[0049] In practical applications, setting the dephosphorizing agent to include lime and iron ore helps to improve the oxidizing properties of ladle slag, thereby improving the dephosphorizing effect. On this basis, setting the mass ratio of lime to iron ore to be in the range of 2:1-5.4:1 helps to form dephosphorizing slag with high alkalinity and high oxidizing properties, so that the thermodynamic and kinetic benefits of the dephosphorizing reaction are both in the optimal range.

[0050] In some embodiments, the amount of lime added is 1.8 kg / t-2.7 kg / t, and the amount of iron ore added is 0.5 kg / t-0.9 kg / t.

[0051] By setting the amount of lime added to 1.8 kg / t-2.7 kg / t and the amount of iron ore added to 0.5 kg / t-0.9 kg / t, the oxidizability of ladle slag can be effectively increased, thereby improving the dephosphorization effect.

[0052] The S300 steps are as follows: Under the condition of oxygen blowing treatment by top lance in vacuum furnace, the molten steel in converter is circulated according to the first preset parameters to obtain the first molten steel; In practical applications, by circulating the molten steel in the converter according to the first preset parameters under the condition of top-lance oxygen blowing treatment in the vacuum furnace, the first molten steel can be obtained. The circulation of molten steel in the vacuum furnace can be used to increase the circulation kinetic energy of the molten steel, and the top-lance oxygen blowing treatment can be used to increase the oxidizability of the steel slag, thereby improving the dephosphorization effect and achieving a further reduction in the phosphorus content of the molten steel.

[0053] In some embodiments, the vacuum value in the first preset parameter is ≤67Pa.

[0054] In practical applications, setting the vacuum level in the first preset parameter to ≤67Pa not only helps promote the decarburization reaction but also helps advance the oxidation reaction towards dephosphorization. Under strong vacuum, the degree to which phosphorus in the molten steel is oxidized and enters the slag phase is increased, thereby improving the dephosphorization effect.

[0055] In some embodiments, the inert gas flow rate in the first preset parameter is 170 m³ / h. 3 / h-180m 3 / h.

[0056] In practical applications, the inert gas can be argon, and the inert gas flow rate in the first preset parameter can be controlled to be 170 m³ / h. 3 / h-180m 3 / h, so as to bring stronger steel circulation through higher argon flow rate, which is conducive to rapid renewal and change of the dephosphorization reaction interface, thereby improving the kinetic energy of steel circulation, improving dephosphorization kinetic efficiency, and improving dephosphorization effect.

[0057] In some embodiments, the molten steel circulation rate in the first preset parameter is 190t / min-195t / min.

[0058] In practical applications, by controlling the molten steel circulation rate in the first preset parameter to be 190t / min-195t / min, the molten steel circulation kinetic energy can be increased through a higher molten steel circulation rate, thereby simultaneously improving the decarburization and dephosphorization efficiency in the vacuum furnace.

[0059] In some embodiments, the phosphorus content in the first molten steel is ≤0.010 wt%.

[0060] In practical applications, the phosphorus content in the first molten steel can be controlled to be ≤0.010wt%, thereby ensuring that the first molten steel obtained after the first molten steel cycle has a sufficiently low phosphorus content and guaranteeing the production quality of low-phosphorus molten steel.

[0061] In some embodiments, under the condition of top-lance oxygen blowing treatment in a vacuum furnace, the molten steel in the converter is circulated according to a first preset parameter to obtain a first molten steel, including: Under the condition that the total iron content in the ladle slag is controlled to be 15%-18% by controlling the amount of iron ore used, and oxygen blowing treatment is performed on the top lance of the vacuum furnace, the molten steel in the converter is circulated according to the first preset parameters to obtain the first molten steel.

[0062] In this embodiment, based on the top-lance oxygen blowing treatment of the vacuum furnace, and further controlling the total iron content in the ladle slag to 15%-18% by adjusting the amount of iron ore used, the converter steel is circulated according to the first preset parameters to obtain the first molten steel. This helps to further enhance the oxidizability of the ladle slag by top-lance oxygen blowing treatment, while ensuring that the ladle slag has sufficient oxidizability to oxidize the phosphorus in the steel. This synergistically improves the dephosphorization effect, achieves a further reduction in the phosphorus content of the molten steel, and avoids the problem of temperature drop or secondary oxidation caused by excessive oxidizability of the ladle slag.

[0063] In some embodiments, the top-gun oxygen flow rate for top-gun oxygen blowing treatment is 1800 Nm. 3 / h-2000Nm 3 / h.

[0064] In practical implementation, the oxygen flow rate of the top lance oxygen blowing treatment can be controlled to 1800 Nm. 3 / h-2000Nm 3 / h, and can control the oxygen flow rate of the top lance to 180m³. 3 -230m 3 This ensures an effective improvement in the oxidizability of ladle slag, which is beneficial for improving dephosphorization and further reducing the phosphorus content in molten steel.

[0065] The S400 process is as follows: the first molten steel is deoxidized and heated to obtain the second molten steel.

[0066] In practical applications, after obtaining the first molten steel, it can be deoxidized and heated to obtain the second molten steel. The deoxidation treatment reduces the oxygen content of the molten steel, which helps prevent oxygen from continuing to participate in the steel slag reaction and causing instability. The heating treatment can compensate for the temperature loss caused by dephosphorization and decarburization during the first molten steel circulation, restoring the molten steel temperature to a range that meets the requirements of subsequent refining and casting.

[0067] In some embodiments, the first molten steel is subjected to deoxidation and heating treatment to obtain a second molten steel, including: Aluminum blocks are added to the first molten steel for deoxidation and heating treatment to obtain the second molten steel.

[0068] In practice, in order to deoxidize and heat the first molten steel, aluminum blocks can be added directly to the first molten steel, thereby making full use of the deoxidizing properties of aluminum and the exothermic effect of the aluminum oxidation reaction, and simultaneously achieving deoxidation and heating.

[0069] In some embodiments, the temperature rise during the heating process is 15°C-25°C.

[0070] In practical applications, the temperature rise during the heating process can be controlled between 15℃ and 25℃ to restore the molten steel temperature to a range that meets the requirements for subsequent refining and casting.

[0071] In some embodiments, the amount of aluminum blocks added is 0.5 kg / t to 0.9 kg / t.

[0072] In practical applications, by controlling the amount of aluminum blocks added to 0.5 kg / t-0.9 kg / t, the deoxidation reaction can be fully carried out and the heat release can be controlled, ensuring that the temperature rise is stable within the target range and avoiding the risk of phosphorus reversion caused by excessive reduction of iron oxide in the slag due to excessive Al.

[0073] The S500 steps are as follows: The second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel; wherein, the second preset parameters are less than the first preset parameters, and both the first and second preset parameters include vacuum degree, inert gas flow rate and molten steel circulation volume.

[0074] In practical applications, the second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel. The second preset parameters are smaller than the first preset parameters. Both the first and second preset parameters include the vacuum degree, inert gas flow rate, and molten steel circulation volume. After the molten steel composition is deoxidized, the circulation kinetic energy of the molten steel can be reduced by decreasing the vacuum degree, circulating argon gas flow rate, and molten steel circulation volume. This avoids the phenomenon of molten steel re-phosphorusing due to excessive disturbance of steel slag in the molten steel with reduced oxidizability, and helps to further improve the dephosphorization effect.

[0075] In some embodiments, the vacuum degree value in the second preset parameter is 600Pa-800Pa.

[0076] In practical applications, setting the vacuum level in the second preset parameter to 600Pa-800Pa helps reduce the circulating kinetic energy of the molten steel, thereby helping to prevent the phosphorus-absorbed slag from undergoing a reduction reaction in the second stage, which would lead to phosphorus reversion.

[0077] In some embodiments, the inert gas flow rate in the second preset parameter is 120 m³ / h. 3 / h-130m 3 / h.

[0078] In practical applications, the inert gas can be argon, and by reducing the inert gas flow rate to the above range, the degree of slag disturbance can be reduced, thereby avoiding the phenomenon of molten steel returning to phosphorus and helping to further improve the dephosphorization effect.

[0079] In some embodiments, the molten steel circulation rate in the second preset parameter is 150t / min-160t / min.

[0080] In practical applications, setting the molten steel circulation rate in the second preset parameter to 150t / min-160t / min helps to reduce the circulation kinetic energy of the molten steel by reducing the circulation rate, thereby helping to prevent the phosphorus-absorbed slag from undergoing a reduction reaction in the second stage, which would lead to phosphorus reversion, and also helps to improve the stability of the molten steel composition.

[0081] In some embodiments, the phosphorus content in low-phosphorus molten steel is ≤0.008wt%.

[0082] In practical applications, the phosphorus content in the low-phosphorus steel obtained by this application is ≤0.008wt%, while traditional processes can generally only obtain a phosphorus content of ≤0.015wt%. Compared with traditional processes, this application can further reduce the phosphorus content in the steel.

[0083] This application improves the dephosphorization capacity of the converter by controlling the temperature of the molten steel in the converter to 1620℃-1650℃, utilizing the principle of low-temperature dephosphorization. Furthermore, by transferring the molten steel to a vacuum furnace, adding a dephosphorizing agent, and subjecting the vacuum furnace to top-lance oxygen blowing, the molten steel is circulated according to a first preset parameter to obtain the first molten steel. This not only reduces the converter smelting cycle and slag consumption and increases the converter operating rate through secondary desulfurization in the vacuum furnace, but also enhances the circulation kinetic energy of the molten steel by utilizing the vacuum furnace circulation and improves the oxidizability of the steel slag by utilizing top-lance oxygen blowing, thereby improving the dephosphorization effect and further reducing the phosphorus content of the molten steel.

[0084] Furthermore, by deoxidizing and heating the first molten steel, a second molten steel is obtained; then, the second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel. The second preset parameters are less than the first preset parameters. Both the first and second preset parameters include vacuum degree, inert gas flow rate, and molten steel circulation volume. After the molten steel composition is deoxidized, the circulation kinetic energy of the molten steel can be reduced by decreasing the vacuum degree, circulating argon gas flow rate, and molten steel circulation volume. This avoids the phenomenon of molten steel re-phosphorus due to excessive disturbance of steel slag in the molten steel with reduced oxidizability, and helps to further improve the dephosphorization effect.

[0085] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are for illustrative purposes only, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0086] Example 1: (1) Under the condition of controlling the iron ratio at 22%, the steel raw materials and converter slag are added to the converter for converter smelting to obtain converter steel. The final temperature of the converter steel is 1625℃ and the phosphorus content in the converter steel is 0.014%.

[0087] (2) The molten steel from the converter is transferred to the vacuum furnace, and after the molten steel is transferred to the vacuum furnace, 2.7 kg / t of lime and 0.9 kg / t of iron ore are added to the molten steel; then, under the condition that the total iron content in the ladle slag is controlled to be 17% by controlling the amount of iron ore used, and the vacuum furnace is subjected to top lance oxygen blowing treatment, the vacuum degree is 65 Pa and the inert gas flow rate is 175 m³ / t. 3 The molten steel in the converter was circulated using parameters of / L and a steel circulation rate of 192t / min to obtain the first molten steel. The phosphorus content in the first molten steel was 0.0075%, and the oxygen flow rate of the top lance for oxygen blowing treatment was 1900 NM. 3 / h, total oxygen blowing volume is 160m³ 3 .

[0088] (3) Add 1.0 kg / t aluminum blocks to the first molten steel for deoxidation and heating treatment. The heating range is 26°C to obtain the second molten steel.

[0089] (4) The vacuum degree is 650 Pa and the inert gas flow rate is 120 m³ / s. 3The second molten steel was circulated with parameters of / L and molten steel circulation rate of 155t / min to obtain low-phosphorus molten steel with a phosphorus content of 0.0072%.

[0090] Example 2: (1) Under the condition of controlling the iron ratio at 23%, the steel raw materials and converter slag are added to the converter for converter smelting to obtain converter steel. The final temperature of the converter steel is 1620℃ and the phosphorus content in the converter steel is 0.012%.

[0091] (2) The molten steel from the converter is transferred to the vacuum furnace, and after the molten steel is transferred to the vacuum furnace, 2.3 kg / t of lime and 0.9 kg / t of iron ore are added to the molten steel; then, under the condition that the total iron content in the ladle slag is controlled to be 16% by controlling the amount of iron ore used, and the vacuum furnace is subjected to top lance oxygen blowing treatment, the vacuum degree is 62 Pa and the inert gas flow rate is 175 m³ / h. 3 The molten steel in the converter was circulated using parameters of / L and a steel circulation rate of 193t / min to obtain the first molten steel. The phosphorus content in the first molten steel was 0.0070%, and the oxygen flow rate of the top lance for oxygen blowing treatment was 1950 NM. 3 / h, total oxygen blowing volume is 110m³ 3 .

[0092] (3) Add 0.7 kg / t aluminum blocks to the first molten steel for deoxidation and heating treatment. The heating range is 18°C ​​to obtain the second molten steel.

[0093] (4) The vacuum degree is 660 Pa and the inert gas flow rate is 120 m³ / s. 3 The second molten steel was circulated with parameters of / L and molten steel circulation rate of 154t / min to obtain low-phosphorus molten steel with a phosphorus content of 0.0071%.

[0094] Example 3: (1) Under the condition of controlling the iron ratio at 24%, the steel raw materials and converter slag are added to the converter for converter smelting to obtain converter steel. The final temperature of the converter steel is 1625℃ and the phosphorus content in the converter steel is 0.010%.

[0095] (2) The molten steel from the converter is transferred to the vacuum furnace, and 1.8 kg / t of lime and 0.5 kg / t of iron ore are added to the molten steel after the transfer. Then, the total iron content in the ladle slag is controlled to be 17% by controlling the amount of iron ore used, and oxygen is blown into the vacuum furnace by the top lance. The vacuum degree is 65 Pa and the inert gas flow rate is 175 m³ / h. 3The molten steel in the converter was circulated using parameters of / L and a steel circulation rate of 192t / min to obtain the first molten steel. The phosphorus content in the first molten steel was 0.0075%, and the oxygen flow rate of the top lance for oxygen blowing treatment was 1900 NM. 3 / h, total oxygen blowing volume is 100m³ 3 .

[0096] (3) Add 0.6 kg / t aluminum blocks to the first molten steel for deoxidation and heating treatment. The heating range is 15°C to obtain the second molten steel.

[0097] (4) The vacuum degree is 650 Pa and the inert gas flow rate is 120 m³ / s. 3 The second molten steel was circulated with a steel circulation rate of 156 t / min to obtain low-phosphorus molten steel with a phosphorus content of 0.0072%.

[0098] Comparative Example 1: (1) Under the condition of controlling the iron ratio to 15%, the steel raw materials and converter slag are added to the converter for converter smelting to obtain converter steel. The final temperature of the converter steel is 1638℃ and the phosphorus content in the converter steel is 0.0160%.

[0099] (2) Transfer the molten steel from the converter to a vacuum furnace, and set the vacuum level to 65 Pa and the inert gas flow rate to 175 m³ / h. 3 The molten steel in the converter is circulated with a rate of 192 t / min to obtain low-phosphorus molten steel with a phosphorus content of 0.0162%.

[0100] Comparative Example 2: (1) Under the condition of controlling the iron ratio at 12%, the steel raw materials and converter slag are added to the converter for converter smelting to obtain converter steel. The final temperature of the converter steel is 1640℃ and the phosphorus content in the converter steel is 0.0190%.

[0101] (2) Transfer the molten steel from the converter to the vacuum furnace, and set the vacuum level to 133 Pa and the inert gas flow rate to 175 m³ / h. 3 The molten steel in the converter is circulated with a parameter of 182t / min / h to obtain low-phosphorus molten steel with a phosphorus content of 0.0166%.

[0102] Based on the above embodiments and comparative examples, it can be seen that by controlling the temperature of the converter steel to 1620℃-1630℃, the dephosphorization capacity of the converter can be improved by utilizing the principle of low-temperature dephosphorization. On this basis, by transferring the converter steel to a vacuum furnace, adding a dephosphorizing agent to the converter steel, and performing top-lance oxygen blowing treatment on the vacuum furnace, the converter steel is circulated according to the first preset parameters to obtain the first molten steel. This not only reduces the converter smelting cycle and slag consumption and improves the converter operating rate by performing secondary desulfurization in the vacuum furnace, but also enhances the circulation kinetic energy of the molten steel by utilizing the vacuum furnace steel circulation and improves the oxidizability of the steel slag by utilizing top-lance oxygen blowing treatment, thereby improving the dephosphorization effect and achieving a further reduction in the phosphorus content of the molten steel.

[0103] Furthermore, by deoxidizing and heating the first molten steel, a second molten steel is obtained; then, the second molten steel is circulated according to the second preset parameters to obtain low-phosphorus molten steel. The second preset parameters are less than the first preset parameters. Both the first and second preset parameters include vacuum degree, inert gas flow rate, and molten steel circulation volume. After the molten steel composition is deoxidized, the circulation kinetic energy of the molten steel can be reduced by decreasing the vacuum degree, circulating argon gas flow rate, and molten steel circulation volume. This avoids the phenomenon of molten steel re-phosphorus due to excessive disturbance of steel slag in the molten steel with reduced oxidizability, and helps to further improve the dephosphorization effect.

[0104] 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 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 this application.

Claims

1. A method for smelting low-phosphorus steel, characterized in that, The method includes: Steel raw materials and converter slag are added to a converter for converter smelting to obtain converter steel, wherein the temperature of the converter steel is 1620℃-1650℃. The molten steel from the converter is transferred to a vacuum furnace, and a dephosphorizing agent is added to the molten steel after the transfer. Under the condition of top lance oxygen blowing treatment in the vacuum furnace, the molten steel in the converter is circulated according to the first preset parameters to obtain the first molten steel; The first molten steel is subjected to deoxidation and heating treatment to obtain the second molten steel. The second molten steel is circulated according to the second preset parameters to obtain the low-phosphorus molten steel; wherein the second preset parameters are less than the first preset parameters, and both the first preset parameters and the second preset parameters include vacuum degree, inert gas flow rate and molten steel circulation volume.

2. The method for smelting low-phosphorus steel according to claim 1, characterized in that, The method satisfies at least one of the following conditions: (1) The vacuum value in the first preset parameter is ≤67Pa; (2) The vacuum degree value in the second preset parameter is 600Pa-800Pa; (3) The inert gas flow rate in the first preset parameter is 170m³. 3 / h-180m 3 / h; (4) The inert gas flow rate in the second preset parameter is 120m³. 3 / h-130m 3 / h; (5) The steel circulation rate in the first preset parameter is 190t / min-195t / min; (6) The steel circulation rate in the second preset parameter is 150t / min-160t / min; (7) The phosphorus content in the molten steel from the converter is ≤0.012 wt%; (8) The phosphorus content in the first molten steel is ≤0.010 wt%; (9) The phosphorus content in the low-phosphorus molten steel is ≤0.008 wt%; (10) The oxygen flow rate of the top lance oxygen blowing treatment is 1800 Nm. 3 / h-2000Nm 3 / h.

3. The method for smelting low-phosphorus steel according to claim 1, characterized in that, The raw materials for molten steel include molten iron and scrap steel. The process of adding the raw materials and converter slag to a converter for smelting to obtain converter steel includes: Under the condition of controlling the iron-to-metal ratio at 20%-25%, the molten steel raw material and converter slag are added to the converter for converter smelting to obtain the converter molten steel.

4. The method for smelting low-phosphorus steel according to claim 3, characterized in that, The phosphorus content in the molten iron is 0.08wt%-0.10wt%.

5. The method for smelting low-phosphorus steel according to claim 1, characterized in that, The dephosphorizing agent comprises lime and iron ore, wherein the mass ratio of lime to iron ore ranges from 2:1 to 5.4:

1.

6. The method for smelting low-phosphorus steel according to claim 5, characterized in that, Under the condition of top-lance oxygen blowing treatment in the vacuum furnace, the molten steel in the converter is circulated according to the vacuum degree, the circulating argon flow rate, and the molten steel circulation rate in the first preset parameters to obtain the first molten steel, including: Under the condition that the total iron content in the ladle slag is controlled to be 15%-18% by controlling the amount of iron ore used, and the vacuum furnace is subjected to top lance oxygen blowing treatment, the molten steel in the converter is circulated according to the first preset parameters to obtain the first molten steel.

7. The method for smelting low-phosphorus steel according to claim 5, characterized in that, The amount of lime added is 1.8 kg / t to 2.7 kg / t, and the amount of iron ore added is 0.5 kg / t to 0.9 kg / t.

8. The method for smelting low-phosphorus steel according to claim 1, characterized in that, The first molten steel is subjected to deoxidation and heating treatment to obtain a second molten steel, comprising: Aluminum blocks are added to the first molten steel to perform the deoxidation treatment and the heating treatment, thereby obtaining the second molten steel.

9. The method for smelting low-phosphorus steel according to claim 1 or 8, characterized in that, The temperature rise range of the heating process is 15℃-25℃.

10. The method for smelting low-phosphorus steel according to claim 8, characterized in that, The amount of aluminum block added is 0.5 kg / t to 0.9 kg / t.

Images