Method for improving production quality of high-aluminum steel

Abstract

According to the method for improving the production quality of the high-aluminum steel, the molten iron is subjected to vanadium extraction in the converter to obtain the semi-steel, then the semi-steel is stirred and desulfurized through the KR desulfurization method, the desulfurization efficiency is improved, the sulfur content in the steel is reduced, and therefore the overall quality of the steel is improved, vanadium slag formed by vanadium extraction is used for partially adsorbing harmful elements, and the production quality of the high-aluminum steel is improved. Generation of inclusions is reduced; semisteel after desulfurization treatment is subjected to steelmaking, a neural network model is trained to control the endpoint carbon content and temperature of a steelmaking converter, the blowing time and the oxygen supply intensity are optimized, and the production efficiency is improved; molten steel is subjected to slag washing, gradient deoxidation is conducted on the molten steel in the steel tapping process of a steelmaking converter, the generation rate of AlO inclusions is controlled, and the situation that a large number of AlO cluster-shaped inclusions are difficult to remove is prevented; the casting powder and the immersion type casting-on long nozzle are adopted for protective casting, oxidation of molten steel is effectively prevented, the risk that AlO in the high-aluminum steel is deposited on the inner wall of the nozzle is reduced, and the product quality of the high-aluminum steel is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of steel smelting, and in particular to a method for improving the production quality of high-aluminum steel. Background Art

[0002] Due to its excellent mechanical properties and corrosion resistance, high-aluminum steel has broad application prospects in high-end equipment manufacturing, aerospace, and automobile manufacturing.

[0003] Traditional high-aluminum steel smelting requires LF / RH refining to ensure deoxidation and inclusion control, but this smelting method is lengthy, resulting in long production times and reduced efficiency. While the existing method of smelting high-aluminum steel from semi-steel (low-silicon hot metal) without refining simplifies the production process, the high aluminum content also increases inclusions, seriously affecting the quality of the molten steel and reducing the quality of the ingots.

[0004] Therefore, it is necessary to propose a method to improve the production quality of high aluminum steel to solve the above problems. Summary of the Invention

[0005] In view of the fact that the above-mentioned existing semi-steel smelting process of high-aluminum steel without refining treatment is relatively simpler, but the high content of aluminum elements also increases the inclusions, which seriously affects the quality of the molten steel and reduces the quality of the ingot, one of the purposes of this application is to provide a method for improving the production quality of high-aluminum steel, by adjusting the production process, intelligently controlling the end point of the steelmaking converter, and gradient deoxidation of the converter to control inclusions and improve product quality.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A method for improving the production quality of high-aluminum steel comprises the following steps:

[0008] Step S10, charging molten iron into a vanadium extraction converter, extracting vanadium from the molten iron and heating it to obtain semi-steel, with the semi-steel temperature being controlled to be greater than 1340° C.;

[0009] Step S20, using a KR desulfurization method to stir and desulfurize the semi-steel, and controlling the sulfur content of the semi-steel to be less than 0.035%;

[0010] Step S30: hoisting the desulfurized semi-steel to a steelmaking converter, adding scrap steel and slag-forming agents into the furnace for steelmaking, stirring the furnace through top and bottom combined blowing; and training a neural network model to control the carbon content and temperature of the steelmaking converter at the end point.

[0011] Step S40, before tapping the steelmaking converter, the empty ladle is subjected to slag washing pretreatment; during the process of tapping the steelmaking converter into the ladle, the molten steel is subjected to slag washing and different deoxidizers are added in stages to perform gradient deoxidation;

[0012] Step S50: hoist the ladle to the turntable, and perform protective pouring using protective slag and an immersed long shroud.

[0013] Preferably, in step S10, the vanadium extraction converter includes the following steps:

[0014] Step S101: 145±10 tons of molten iron is loaded into the vanadium extraction converter, oxygen is blown from the top, and the oxygen supply pressure in the furnace is controlled to 0.65-0.75 MPa, the oxygen supply flow rate is 15,000-18,000 Nm3 / h, and the oxygen lance position adopts a "low-high-low" three-stage constant pressure variable mode;

[0015] Step S102: After the lower oxygen lance is ignited, 2.0-4.0 kg / t of Class II ferrosilicon is added into the furnace to prepare silicon and increase the temperature, ensuring that the total silicon content is greater than 0.20%;

[0016] Step S103, controlling the oxygen supply time in the furnace to 4.5 to 6.5 minutes according to the molten iron temperature, and controlling the temperature of the semi-steel discharged from the vanadium extraction converter to be greater than 1370°C;

[0017] Step S104: During the process of discharging the semi-steel from the vanadium extraction converter into the semi-steel ladle, 140 kg of ferrosilicon and 140 kg of ferroaluminum are added to the semi-steel for deoxidation, and a carburizer is added to the semi-steel ladle to control the carbon content of the semi-steel to be greater than 2.8% and the temperature of the semi-steel to be greater than 1340°C.

[0018] Step S105: After the semi-steel is produced from the vanadium-extracting converter, 0.5 kg / t of heat-insulating agent is evenly spread on the surface of the semi-steel.

[0019] Preferably, before step S101, that is, before the molten iron is put into the furnace, 5 to 8 tons of pig iron blocks are first added into the furnace.

[0020] Preferably, in step S20, the KR desulfurization method includes the following steps:

[0021] Step S201: hoist the half ladle to the KR station and load the half ladle into the hot metal ladle at a rate of 140±10 tons per ladle, ensuring that the center line of the hot metal ladle is aligned with the center line of the agitator with a positive and negative error of ≤50mm;

[0022] Step S202: Stirring the semi-steel for 8 to 10 minutes at a stirrer speed of 80 to 125 rpm. After a stable vortex is formed in the early stage of stirring, adding activated lime powder in small amounts to the molten iron ladle to mix the semi-steel with the activated lime powder, and controlling the sulfur content in the semi-steel to be less than 0.035%. The activated lime powder is added in 3 to 4 times, with at least 30 seconds between each addition.

[0023] Step S203: 3 minutes before the end of stirring, the stirrer is evenly decelerated and the speed is maintained at not less than 80 rpm;

[0024] Step S204: After the stirring is completed, the high-sulfur slag is mechanically removed;

[0025] Step S205: After the slag is removed, add 0.5 kg / t of heat preservation agent to the semi-steel.

[0026] Preferably, in step S202, the mass percentage of effective CaO in the active lime powder is 94%, the activity is ≥350 ml, and the total added amount of the active lime powder is <8 kg / t semi-steel, and the single added amount is ≤2 kg / t semi-steel.

[0027] Preferably, in step S202, the stirrer speed should be 5 to 10 revolutions lower than the required speed when adding active lime powder, and should be evenly increased to the required speed when 80 to 100 kg of material is left, and should be adjusted according to sparks and brightness.

[0028] Preferably, in step S30, hoisting the desulfurized semi-steel to a steelmaking converter, adding scrap steel and a slag-forming agent into the converter for steelmaking, and stirring the converter by top and bottom combined blowing during the process includes:

[0029] Within 2 hours, the half ladle treated with the KR desulfurization method is lifted to the steelmaking converter, and scrap steel and slag-forming agent are added to the furnace for steelmaking. During the process, the furnace is stirred by top blowing oxygen and bottom blowing inert gas.

[0030] Preferably, in step S30, the training of the neural network model to control the endpoint carbon content and temperature of the steelmaking converter includes:

[0031] Based on historical smelting data, a neural network model is trained to predict the endpoint carbon content and temperature of the steelmaking converter in real time, guiding whether additional blowing or coolant addition is needed before tapping, ensuring that the semi-steel oxygen activity is ≤20ppm and the temperature error is ±5°C; wherein, the historical smelting data includes the CO / CO2 ratio in the flue gas, the furnace mouth flame spectrum and the auxiliary gun TSC measurement value.

[0032] Preferably, in step S40, before tapping the steelmaking converter, the empty ladle is subjected to slag washing pretreatment; during the process of tapping the steelmaking converter into the ladle, the molten steel is subjected to slag washing and different deoxidizers are added in stages to perform gradient deoxidation, which includes:

[0033] Before tapping, 2 to 3 kg / t of pre-melted slag is added to the empty ladle, and argon is blown from the bottom of the empty ladle for pre-stirring. During the process of tapping from the steelmaking converter into the ladle, FeSi alloy is first added for pre-deoxidation to reduce the oxygen concentration to 80 to 100 ppm. Then, aluminum blocks with 80% of the target aluminum content are added for final deoxidation to reduce the oxygen concentration to 20 to 30 ppm, and the flow rate of argon blown from the bottom of the ladle is increased for strong stirring. After tapping from the steelmaking converter is completed, CaSi wire and AI wire with 20% of the target aluminum content are fed, and the flow rate of argon blown from the bottom of the ladle is reduced for weak stirring to reduce the oxygen concentration to below 10 ppm.

[0034] Preferably, in step S50, the protective slag comprises 35-40% CaO, 8-12% Al2O3, 20-25% SiO2, 10-12% Na2O+K2O, 1-2% Li2O, 3-5% B2O3 and 3-4% free C.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] First, the production process was adjusted to first extract vanadium from the molten iron in the converter and then desulfurize it. This effectively reduced iron loss, improved desulfurization efficiency, and reduced the sulfur content in the steel, thereby improving the overall quality of the steel. In addition, the vanadium slag formed in the vanadium extraction stage can partially absorb harmful elements, reducing the formation of inclusions and laying the foundation for subsequent deep desulfurization and pure steel smelting.

[0037] Second, the neural network model is trained to intelligently control the carbon content and temperature at the end of the steelmaking converter, optimizing the blowing time and oxygen supply intensity, reducing unnecessary re-blowing, and thus improving production efficiency.

[0038] 3. During the process of tapping from the steelmaking converter to the ladle, the molten steel is subjected to gradient deoxidation, which controls the generation rate of Al2O3 inclusions and prevents a large number of Al2O3 clustered inclusions from being difficult to remove. In addition, Al wire and CaSi wire are fed to improve the morphology and distribution of inclusions, reduce the risk of continuous casting nozzle blockage, and prevent inclusions on the nozzle wall from falling off and entering the molten steel, affecting product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 A schematic flow chart of a method for improving the production quality of high-aluminum steel provided in this application;

[0041] Figure 2 Schematic diagram of the process of predicting the endpoint carbon content and temperature of a steelmaking converter using the neural network model provided in this application. DETAILED DESCRIPTION

[0042] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0043] As used herein, the terms "comprise," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used in this specification are intended only to describe specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0047] Figure 1 This is a flow chart of a method for improving the production quality of high-aluminum steel provided in this application. The method for improving the production quality of high-aluminum steel comprises the following steps:

[0048] Step S10, charging molten iron into a vanadium extraction converter, extracting vanadium from the molten iron and heating it to obtain semi-steel, with the semi-steel temperature being controlled to be greater than 1340° C.;

[0049] Step S20, using a KR desulfurization method to stir and desulfurize the semi-steel, controlling the sulfur content of the semi-steel to be less than 0.035%;

[0050] Step S30: hoisting the desulfurized semi-steel to a steelmaking converter, adding scrap steel and slag-forming agents into the furnace for steelmaking, stirring the furnace through top and bottom combined blowing; and training a neural network model to control the carbon content and temperature of the steelmaking converter at the end point.

[0051] Step S40, before tapping the steelmaking converter, the empty ladle is subjected to slag washing pretreatment; during the process of tapping the steelmaking converter into the ladle, the molten steel is subjected to slag washing and different deoxidizers are added in stages to perform gradient deoxidation;

[0052] Step S50: hoist the ladle to the turntable, and perform protective pouring using protective slag and an immersed long shroud.

[0053] The method for improving the production quality of high-aluminum steel comprises the following steps: firstly subjecting molten iron to vanadium extraction in a converter to obtain semi-steel, and then using a KR desulfurization method to stir and desulfurize the semi-steel, thereby improving desulfurization efficiency, reducing the sulfur content in the steel, and thus improving the overall quality of the steel. The vanadium slag formed by vanadium extraction is used to partially adsorb harmful elements (such as phosphorus and sulfur), thereby reducing the generation of inclusions. The desulfurized semi-steel is then steel-made, and a neural network model is trained to intelligently control the carbon content and temperature at the end of the steelmaking converter, thereby optimizing the blowing time and oxygen supply intensity, reducing unnecessary re-blowing, and thus improving production efficiency. The molten steel is slag-washed, and the molten steel is gradiently deoxidized during the process of being tapped from the steelmaking converter into the ladle, thereby controlling the generation rate of Al2O3 inclusions and preventing a large number of Al2O3 clustered inclusions from being difficult to remove. Furthermore, protective slag and an immersed long shroud are used for protective pouring, thereby effectively preventing oxidation of the molten steel and reducing the risk of Al2O3 deposition on the inner wall of the shroud in the high-aluminum steel, thereby improving the product quality of the high-aluminum steel.

[0054] Furthermore, in step S10, the vanadium extraction converter includes the following steps:

[0055] Step S101: 145±10 tons of molten iron is loaded into the vanadium extraction converter, oxygen is blown from the top, and the oxygen supply pressure in the furnace is controlled to 0.65-0.75 MPa, the oxygen supply flow rate is 15,000-18,000 Nm3 / h, and the oxygen lance position adopts a "low-high-low" three-stage constant pressure variable mode;

[0056] Step S102: After the lower oxygen lance is ignited, 2.0-4.0 kg / t of Class II ferrosilicon is added into the furnace to prepare silicon and increase the temperature, ensuring that the total silicon content is greater than 0.20%;

[0057] Step S103, controlling the oxygen supply time in the furnace to 4.5 to 6.5 minutes according to the molten iron temperature, and controlling the temperature of the semi-steel discharged from the vanadium extraction converter to be greater than 1370°C;

[0058] Step S104: During the process of discharging the semi-steel from the vanadium extraction converter into the semi-steel ladle, 140 kg of ferrosilicon and 140 kg of ferroaluminum are added to the semi-steel for deoxidation, and a carburizer is added to the semi-steel ladle to control the carbon content of the semi-steel to be greater than 2.8% and the temperature of the semi-steel to be greater than 1340°C.

[0059] Step S105: After the semi-steel is produced from the vanadium-extracting converter, 0.5 kg / t of heat-insulating agent is evenly spread on the surface of the semi-steel.

[0060] In the above technical solution, out of consideration for production capacity and ironmaking costs, the manufacturer adjusted the ironmaking structural raw materials and changed the ore raw materials, causing the sulfur content of molten iron to increase, and the molten iron showed high sulfur, low temperature and low carbon characteristics. This application is different from the traditional smelting process. First, the molten steel is subjected to a vanadium converter, and the oxygen supply pressure in the furnace is controlled at 0.65-0.75Mpa, and the oxygen supply flow rate is 15000-18000Nm3 / h to avoid excessive iron oxidation; the lance position of the oxygen lance adopts a "low-high-low" three-stage constant pressure change mode, specifically a low lance position in the early stage to enhance the stirring of the molten pool and promote the oxidation of vanadium and silicon, a high lance position in the middle stage to slow down the oxidation rate and avoid excessive carbon combustion, and a low lance position in the final stage to ensure that the vanadium slag is fully aggregated and reduce iron loss; Class II ferrosilicon is added to the molten iron for silicon addition and temperature increase. Class II ferrosilicon uses high silicon ferrosilicon with Si≥75%, thereby reducing the introduction of impurities (such as Al and P). The specific addition amount is 2.0-4.0kg / t semi-steel to prevent excessive silicon Increase SiO2 in the slag and reduce the grade of vanadium slag. It should be noted that the initial silicon content in the molten iron is low; adjust the oxygen supply time in the furnace based on the vanadium, silicon and carbon content in the molten iron, and control the temperature of the semi-steel discharged from the vanadium extraction converter to be greater than 1370°C to ensure the fluidity of the semi-steel and create temperature conditions for subsequent KR desulfurization; add 140 kg of ferrosilicon and ferroaluminum to the semi-steel for deoxidation treatment to reduce the dissolved oxygen in the semi-steel and prevent the semi-steel from churning during the subsequent KR stirring desulfurization process, and then add a recarburizer to avoid sulfur recovery, control the semi-steel temperature to be greater than 1340°C, and prevent insufficient dissolution of the recarburizer; specifically, the insulation agent can be but is not limited to carbonized rice husks. The insulation agent can reduce the heat dissipation of the semi-steel ladle, prevent the temperature from dropping suddenly, and ensure the smooth progress of the subsequent KR desulfurization method.

[0061] Furthermore, before step S101, that is, before the molten iron is put into the furnace, 5 to 8 tons of pig iron blocks are first added into the furnace.

[0062] In the above technical solution, since the carbon in the molten iron will be partially oxidized into CO and / or CO2 during the vanadium extraction oxygen blowing process, resulting in a decrease in the carbon content of the semi-steel, the carbon is increased by adding pig iron blocks to replenish the carbon content of the semi-steel to reduce the oxidation tendency of iron, reduce iron loss, and improve metal yield. The addition of pig iron blocks can also increase silicon. The oxidation of silicon is a strongly exothermic reaction. Increasing silicon can quickly increase the molten pool temperature, ensuring that the semi-steel temperature is greater than 1370°C, providing sufficient temperature conditions for subsequent processes.

[0063] Furthermore, in step S20, the KR desulfurization method includes the following steps:

[0064] Step S201: hoist the half ladle to the KR station and load the half ladle into the hot metal ladle at a rate of 140±10 tons per ladle, ensuring that the center line of the hot metal ladle is aligned with the center line of the agitator with a positive and negative error of ≤50mm;

[0065] Step S202: Stirring the semi-steel for 8 to 10 minutes at a stirrer speed of 80 to 125 rpm. After a stable vortex is formed in the early stage of stirring, adding activated lime powder in small amounts to the molten iron ladle to mix the semi-steel with the activated lime powder, and controlling the sulfur content in the semi-steel to be less than 0.035%. The activated lime powder is added in 3 to 4 times, with at least 30 seconds between each addition.

[0066] Step S203: 3 minutes before the end of stirring, the stirrer is evenly decelerated and the speed is maintained at not less than 80 rpm;

[0067] Step S204: After the stirring is completed, the high-sulfur slag is mechanically removed;

[0068] Step S205: After the slag is removed, add 0.5 kg / t of heat preservation agent to the semi-steel.

[0069] In the above technical solution, the KR desulfurization method is a molten iron pretreatment desulfurization technology. When using it, the first thing to do is to ensure the accuracy of the alignment and ensure that the vortex is stable when the agitator rotates to avoid eccentric force causing equipment vibration or uneven desulfurization; a stable vortex is formed by the rotation of the agitator, and the required speed is determined according to the tank diameter and the amount of semi-steel to ensure sufficient contact between the desulfurizer and the sulfur in the semi-steel. The stirring time is controlled to ensure that the sulfur fully migrates from the liquid phase to the slag phase; active lime powder is used as a desulfurizer to react with sulfur to form CaS which enters the slag phase for removal, and active lime powder is added in 3 to 4 times, each time The interval between each addition is at least 30 seconds, which can prevent the lime powder from clumping and improve the utilization rate of the lime powder; the agitator is evenly decelerated within 3 minutes to avoid the collapse of the vortex caused by a sudden drop, which causes the slag-steel mixture to roll up, and at the same time promotes the aggregation and floating of CaS, which is convenient for subsequent slag skimming; inclined slag skimming or nitrogen-assisted blowing is used to remove high-sulfur slag mainly composed of CaS, so that the slag skimming rate is greater than 95% and the slag thickness is ≤20mm, preventing sulfur from dissolving back or contaminating the next process; specifically, the thermal insulation agent can be but is not limited to carbonized rice husks, which are used to reduce temperature drop and prevent secondary oxidation.

[0070] Furthermore, in step S202, the mass percentage of effective CaO in the active lime powder is 94%, the activity is ≥350 ml, and the total added amount of the active lime powder is <8 kg / t semi-steel, and the single added amount is ≤2 kg / t semi-steel.

[0071] In the above technical solution, the mass percentage of effective CaO is 94%, which improves the desulfurization efficiency and reduces the interference of impurities (such as SiO2 and MgO) on the slag system; the activity is ≥350ml, which can accelerate sulfur migration, quickly react and reduce the lime suspension time, thereby shortening the stirring time; the total addition amount of active lime powder is <8kg / t semi-steel, preventing excessive addition from causing excessive slag volume and increased temperature drop; the single addition amount of active lime powder is ≤2kg / t semi-steel, which can effectively avoid local lime agglomeration, ensure the uniform dispersion of lime, and improve utilization rate.

[0072] Furthermore, in step S202, the agitator speed should be 5 to 10 revolutions lower than the required speed when adding active lime powder, and should be evenly increased to the required speed when 80 to 100 kg of material is left, and should be adjusted according to sparks and brightness.

[0073] In this technical solution, the agitator speed is controlled to decrease when adding active lime powder, thereby reducing vortex intensity and preventing the lime powder from being directly blown away by the airflow, ensuring that the lime sinks deep into the molten pool. When 80-100 kg of material remains, the speed is evenly increased to the required level to enhance vortex stirring and promote thorough mixing of unreacted lime powder with the semi-steel. Each time new lime is added, the agitator speed is repeatedly reduced and then evenly increased to ensure efficient utilization of each batch of lime. After the addition of material is completed, the speed is dynamically adjusted based on the spark spatter and brightness. Specifically, high spark brightness indicates a strong reaction, requiring a reduction in speed to prevent spatter, while low spark brightness indicates a weak reaction, requiring a higher speed to maximize efficiency.

[0074] Furthermore, in step S30, the semi-steel after desulfurization is hoisted to a steelmaking converter, scrap steel and slag-forming agent are added to the converter to perform steelmaking, and the furnace is stirred by top and bottom combined blowing during the process, including:

[0075] Within 2 hours, the half ladle treated with the KR desulfurization method is lifted to the steelmaking converter, and scrap steel and slag-forming agent are added to the furnace for steelmaking. During the process, the furnace is stirred by top blowing oxygen and bottom blowing inert gas.

[0076] In the above technical solution, semi-steel treated by KR desulfurization method is steel-made within 2 hours to avoid the semi-steel sticking to the molten iron tank due to long waiting time and affecting the loading amount; the slag-making agents are lime, fluorite and dolomite, among which the mass percentage of effective CaO in the lime is 92%, the lime is used for dephosphorization and desulfurization, the fluorite is used to reduce the slag melting point, and the dolomite is used to protect the furnace lining and control the slag viscosity; when top blowing oxygen, the lance position adopts a "high-low-medium" three-stage constant pressure variable mode, specifically, a high lance position is used in the slagging period, a low lance position is used in the decarbonization period, and a medium lance position is used for end point control, so as to optimize the impact pit depth and improve steelmaking efficiency; the bottom blowing of inert gas stirs the furnace to uniformize the composition and temperature of the molten pool; the use of top and bottom composite blowing can effectively improve steelmaking efficiency and reduce inclusions in the molten steel.

[0077] Furthermore, in step S30, the training neural network model controls the endpoint carbon content and temperature of the steelmaking converter, including:

[0078] Based on historical smelting data, a neural network model is trained to predict the endpoint carbon content and temperature of the steelmaking converter in real time, guiding whether additional blowing or coolant addition is needed before tapping, ensuring that the semi-steel oxygen activity is ≤20ppm and the temperature error is ±5°C; wherein, the historical smelting data includes the CO / CO2 ratio in the flue gas, the furnace mouth flame spectrum and the auxiliary gun TSC measurement value.

[0079] In the above technical solution, the control of the converter end point carbon content and temperature is very important, among which the fluctuation of the end point carbon directly affects the quality of the molten steel, thereby affecting the decarburization efficiency and smelting cost. Figure 2 As shown, the CO / CO2 ratio in flue gas, the furnace mouth flame spectrum, and the secondary lance TSC measurements are collected to train a neural network model. This allows for real-time prediction of the carbon content and temperature at the steelmaking converter endpoint based on actual conditions, achieving flexible and accurate control of the converter endpoint. Specifically, when the carbon content predicted by the neural network model exceeds the target value, supplemental blowing is triggered. When the temperature predicted by the neural network model exceeds the target temperature, coolant addition is triggered, achieving precise control and improving product quality.

[0080] Furthermore, in step S40, before tapping the steelmaking converter, the empty ladle is subjected to slag washing pretreatment; during the process of tapping the steelmaking converter into the ladle, the molten steel is subjected to slag washing and different deoxidizers are added in stages to perform gradient deoxidation, including:

[0081] Before tapping, 2 to 3 kg / t of pre-melted slag is added to the empty ladle, and argon is blown from the bottom of the empty ladle for pre-stirring. During the process of tapping from the steelmaking converter into the ladle, FeSi alloy is first added for pre-deoxidation to reduce the oxygen concentration to 80 to 100 ppm. Then, aluminum blocks with 80% of the target aluminum content are added for final deoxidation, and the flow rate of argon blown from the bottom of the ladle is increased for strong stirring to reduce the oxygen concentration to 20 to 30 ppm. After tapping from the steelmaking converter is completed, CaSi wire and AI wire with 20% of the target aluminum content are fed, and the flow rate of argon blown from the bottom of the ladle is reduced for weak stirring to reduce the oxygen concentration to below 10 ppm.

[0082] In the above technical solution, the pre-melted slag consists of 50-55% CaO, 30-35% Al2O3, and ≤5% SiO2. Argon is blown from the bottom of the empty ladle for pre-stirring, ensuring a uniform slag layer covering the ladle bottom. Different deoxidizers are added in stages to achieve a gradient deoxidation of the molten steel, controlling the formation rate of Al2O3 inclusions and preventing the difficult removal of large Al2O3 clusters. Specifically, the deoxidizer is added in three stages: the first stage is when FeSi alloy is added at 1 / 4 of the tapping volume to reduce the dissolved oxygen to 80-100 ppm. The second stage is when aluminum blocks (80% of the target aluminum content) are added at 3 / 4 of the tapping volume, using molten steel impact to promote dissolution. The third stage is when Al wire (20% of the target aluminum content) and CaSi wire are added after tapping is complete. This improves the morphology and distribution of inclusions, reduces the risk of continuous casting nozzle blockage, and prevents inclusions from falling off the nozzle wall into the molten steel, impacting product quality. Flexible adjustment of the stirring intensity promotes inclusion removal and improves molten steel quality.

[0083] Furthermore, in step S50, the mold slag comprises CaO 35-40%, Al2O3 8-12%, SiO2 20-25%, Na2O+K2O 10-12%, Li2O 1-2%, B2O3 3-5% and free C 3-4%.

[0084] In the above technical solution, CaO and SiO2 are used to form low-melting-point silicates (such as CaSiO3), thereby reducing slag viscosity and promoting the formation of a uniform liquid slag layer. B2O3 and Li2O synergistically lower the slag crystallization temperature, expand the glassy region, improve the thermal resistance of the slag film, and reduce ingot vibration marks. Al2O3 neutralizes Al2O3 inclusions floating in the molten steel, preventing sudden changes in slag composition and maintaining stability. Alkali metal oxides (Na2O + K2O) inhibit the reduction of SiO2 by providing free oxygen, reducing the reaction between SiO2 in the slag and aluminum in the steel, thereby avoiding aluminum loss. Free carbon decomposes and releases gases to form a porous structure, delaying slag sintering, ensuring uniform heat transfer, and preventing secondary oxidation of the molten steel. In summary, this mold slag can achieve the goals of inclusion removal, thermal insulation, lubrication, and reducing surface depressions and cracks on the ingot, further improving product quality.

[0085] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for improving the production quality of high-aluminum steel, characterized in that: It includes the following steps: Step S10, charging molten iron into a vanadium extraction converter, extracting vanadium from the molten iron and heating it to obtain semi-steel, with the semi-steel temperature being controlled to be greater than 1340° C.; Step S20, using a KR desulfurization method to stir and desulfurize the semi-steel, and controlling the sulfur content of the semi-steel to be less than 0.035%; Step S30: hoisting the desulfurized semi-steel to a steelmaking converter, adding scrap steel and slag-forming agents into the furnace for steelmaking, stirring the furnace through top and bottom combined blowing; and training a neural network model to control the carbon content and temperature of the steelmaking converter at the end point. Step S40, before tapping the steelmaking converter, the empty ladle is subjected to slag washing pretreatment; during the process of tapping the steelmaking converter into the ladle, the molten steel is subjected to slag washing and different deoxidizers are added in stages to perform gradient deoxidation; Step S50: hoist the ladle to the turntable, and perform protective pouring using protective slag and an immersed long shroud.

2. The method for improving the production quality of high-aluminum steel according to claim 1, characterized in that: In step S10, the vanadium extraction converter includes the following steps: Step S101: 145±10 tons of molten iron is loaded into the vanadium-extracting converter. Oxygen is blown top-down. The oxygen pressure in the furnace is controlled at 0.65-0.75 MPa and the oxygen flow rate is 15,000-18,000 Nm³ / h. The oxygen lance adopts a "low-high-low" three-stage constant pressure variable mode. Step S102: After the lower oxygen lance is ignited, 2.0-4.0 kg / t of Class II ferrosilicon is added into the furnace to prepare silicon and increase the temperature, ensuring that the total silicon content is greater than 0.20%; Step S103, controlling the oxygen supply time in the furnace to 4.5 to 6.5 minutes according to the molten iron temperature, and controlling the temperature of the semi-steel discharged from the vanadium extraction converter to be greater than 1370°C; Step S104: During the process of discharging the semi-steel from the vanadium extraction converter into the semi-steel ladle, 140 kg of ferrosilicon and 140 kg of ferroaluminum are added to the semi-steel for deoxidation, and a carburizer is added to the semi-steel ladle to control the carbon content of the semi-steel to be greater than 2.8% and the temperature of the semi-steel to be greater than 1340°C. Step S105: After the semi-steel is produced from the vanadium-extracting converter, 0.5 kg / t of heat-insulating agent is evenly spread on the surface of the semi-steel.

3. The method for improving the production quality of high-aluminum steel according to claim 2, characterized in that: Before step S101, that is, before the molten iron is put into the furnace, 5 to 8 tons of pig iron blocks are first added into the furnace.

4. The method for improving the production quality of high-aluminum steel according to claim 3, characterized in that: In step S20, the KR desulfurization method includes the following steps: Step S201: hoist the half ladle to the KR station and load the half ladle into the hot metal ladle at a rate of 140±10 tons per ladle, ensuring that the center line of the hot metal ladle is aligned with the center line of the agitator with a positive and negative error of ≤50mm; Step S202: Stirring the semi-steel for 8 to 10 minutes at a stirrer speed of 80 to 125 rpm. After a stable vortex is formed in the early stage of stirring, adding activated lime powder in small amounts to the molten iron ladle to mix the semi-steel with the activated lime powder, and controlling the sulfur content in the semi-steel to be less than 0.035%. The activated lime powder is added in 3 to 4 times, with at least 30 seconds between each addition. Step S203: 3 minutes before the end of stirring, the stirrer is evenly decelerated and the speed is maintained at not less than 80 rpm; Step S204: After the stirring is completed, the high-sulfur slag is mechanically removed; Step S205: After the slag is removed, add 0.5 kg / t of heat preservation agent to the semi-steel.

5. The method for improving the production quality of high-aluminum steel according to claim 4, characterized in that: In step S202, the mass percentage of effective CaO in the active lime powder is 94%, the activity is ≥350 ml, and the total added amount of the active lime powder is less than 8 kg / t semi-steel, and the single added amount is ≤2 kg / t semi-steel.

6. The method for improving the production quality of high-aluminum steel according to claim 4, characterized in that: In step S202, the stirrer speed should be 5 to 10 revolutions lower than the required speed when adding active lime powder, and should be evenly increased to the required speed when 80 to 100 kg of material is left, and should be adjusted according to sparks and brightness.

7. The method for improving the production quality of high-aluminum steel according to claim 4, characterized in that: In step S30, the semi-steel after desulfurization is hoisted to a steelmaking converter, scrap steel and slag-forming agent are added to the converter for steelmaking, and the furnace is stirred by top and bottom combined blowing during the process, which includes: Within 2 hours, the half ladle treated with the KR desulfurization method is lifted to the steelmaking converter, and scrap steel and slag-forming agent are added to the furnace for steelmaking. During the process, the furnace is stirred by top blowing oxygen and bottom blowing inert gas.

8. The method for improving the production quality of high-aluminum steel according to claim 7, characterized in that: In step S30, the training of the neural network model to control the endpoint carbon content and temperature of the steelmaking converter includes: Based on historical smelting data, a neural network model is trained to predict the endpoint carbon content and temperature of the steelmaking converter in real time, guiding whether additional blowing or coolant addition is needed before tapping, ensuring that the semi-steel oxygen activity is ≤20ppm and the temperature error is ±5°C; wherein, the historical smelting data includes the CO / CO2 ratio in the flue gas, the furnace mouth flame spectrum and the auxiliary gun TSC measurement value.

9. The method for improving the production quality of high-aluminum steel according to claim 1, characterized in that: In the step S40, before tapping the steel from the steelmaking converter, the empty ladle is pre-treated by slag washing; During the process of tapping steel from the steelmaking converter into the ladle, the molten steel is slag washed and different deoxidizers are added in stages for gradient deoxidation, including: Before tapping, add 2-3 kg / t of pre-melted slag into the empty ladle, and blow argon gas from the bottom of the empty ladle for pre-stirring; During the process of tapping steel from the steelmaking converter into the ladle, FeSi alloy is first added for pre-deoxidation to reduce the oxygen concentration to 80-100 ppm; then aluminum blocks with 80% of the target aluminum content are added for final deoxidation, and the argon flow rate at the bottom of the ladle is increased for strong stirring to reduce the oxygen concentration to 20-30 ppm; after the steelmaking converter is tapped, CaSi wire and AI wire with 20% of the target aluminum content are fed, and the argon flow rate at the bottom of the ladle is reduced for weak stirring to reduce the oxygen concentration to below 10 ppm.

10. The method for improving the production quality of high-aluminum steel according to claim 1, characterized in that: In the step S50, the mold slag comprises 35-40% CaO, 8-12% Al2O3, 20-25% SiO2, 10-12% Na2O+K2O, 1-2% Li2O, 3-5% B2O3 and 3-4% free C.

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