A steelmaking production method for freely regulating the composition of molten steel in an LF refining furnace

Abstract

The application discloses a steelmaking production method for freely regulating LF refining furnace molten steel composition, and belongs to the technical field of steel metallurgy continuous casting and refining, and comprises the following steps: obtaining current composition data of molten steel in a refining furnace; determining a target adding amount of an iron-based diluent based on the existence of an over-standard element in the current composition data, wherein the target adding amount is determined based on the current mass of the molten steel, the current content of the over-standard element and a target content; controlling the iron-based diluent to be added into the refining furnace in the target adding amount; and performing temperature compensation control on the refining furnace in the process of adding the iron-based diluent. The method realizes active dilution of the over-standard element and multi-process collaborative control, and guarantees the heat balance of the refining process and the continuity of the furnace-machine connection.

Description

Technical Field

[0001] This invention relates to a steelmaking method, specifically a steelmaking production method for freely controlling the composition of molten steel in an LF refining furnace, belonging to the field of continuous casting refining technology in iron and steel metallurgy. Background Technology

[0002] The LF (Ladle Furnace) is a commonly used ladle refining equipment in steel enterprises. Its main function is to perform refining operations such as heating, fine-tuning of composition, deoxidation, desulfurization, and removal of inclusions in molten steel before vacuum degassing. With the increasing demands of downstream users for steel quality, the accuracy of composition control in the LF refining process has become one of the key factors determining the quality of the final product.

[0003] Currently, domestic and foreign steel companies mainly employ the following technical approaches to control the composition of refined LF (sulfuric acid).

[0004] (I) Current Status of Domestic Technology Domestic steel companies primarily address the issue of excessive refined LF (sulfuric acid) content by optimizing raw material control, improving equipment precision, and strengthening operational procedures. Specific technical measures include: (1) Raw material quality control: Establish a scrap steel classification and stacking and testing system to reduce residual element fluctuations; adopt online alloy composition detection technology to ensure the purity of added alloys; and improve the quality of steel raw materials through molten iron three-stage stripping technology. (2) Process optimization and improvement: Develop an alloy yield prediction model to improve the accuracy of addition; optimize the LF furnace argon blowing system and slag ratio to reduce composition fluctuations; and implement management measures such as alloy addition confirmation system and process data traceability system.

[0005] However, the aforementioned technical methods are all based on a preventative approach, lacking efficient proactive control measures for existing component exceedances. Some processes have attempted to use ordinary scrap steel for dilution, but due to the large fluctuations in scrap steel composition, the dilution effect is unstable and easily introduces new harmful elements, making it difficult to meet the requirements for high-precision component control.

[0006] (II) Current Status of Foreign Technology Advanced foreign steel companies (such as Nippon Steel of Japan and ThyssenKrupp of Germany) mainly focus on digital and intelligent upgrades in LF refining composition control: adopting a fully automated batching system, combined with furnace gas analysis and online detection of molten steel composition, to achieve precise closed-loop control of alloy addition; developing multifunctional refining agents and composite alloys to optimize composition adjustment efficiency; and for heats with excessive composition, they mostly use converter remelting or recasting with lower-grade steel, without establishing an efficient and economical proactive control technology system for excessive composition.

[0007] Currently, Chinese invention patent CN119913380A discloses a method for rapid dealuminization of molten steel containing aluminum high-titanium nickel-based alloys. When the aluminum content of molten steel in the LF furnace exceeds the standard (>0.20%), lime and fluorite are added, combined with strong stirring at the bottom of the ladle and a corresponding power supply system to achieve rapid dealuminization. This type of method removes aluminum by adding a specific removal agent to react chemically with the excess element. However, chemical removal methods are usually only effective for a single element and may affect the slag basicity and the cleanliness of the molten steel, resulting in a narrow process window.

[0008] Therefore, developing a steelmaking production method that can overcome the above defects and freely control the composition of molten steel in an LF refining furnace has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] The technical problem to be solved by this invention is that, in the above-mentioned existing technologies, it is difficult to achieve efficient and precise control and maintain smooth production without introducing new impurities when the composition exceeds the standard. This invention proposes a steelmaking production method that allows for free control of the composition of molten steel in an LF refining furnace, thereby achieving active dilution of excessive elements and multi-process coordinated control, ensuring the thermal balance and continuous connection between the furnace and the refining process.

[0010] The technical solution of this invention to solve the above technical problems is: A steelmaking method for freely controlling the composition of molten steel in an LF refining furnace includes: acquiring current composition data of molten steel in the refining furnace; determining a target amount of iron-based diluent to be added based on the presence of excessive elements in the current composition data, wherein the target amount is determined based on the current mass of the molten steel, the current content of the excessive elements, and the target content; controlling the addition of the target amount of iron-based diluent to the refining furnace; and implementing temperature compensation control for the refining furnace during the addition of the iron-based diluent.

[0011] Technical advantages: This invention utilizes the extremely low content of this element in pure iron, i.e., iron-based diluents, to dilute the concentration of molten steel, ultimately ensuring that the steel composition meets the target requirements. This avoids the risk of secondary pollution caused by impurities introduced in traditional scrap steel dilution methods. Simultaneously, the target addition amount is determined based on the current quality of the molten steel, the current content of the excess element, and the target content, ensuring the accuracy of the dilution calculation and composition control. Furthermore, temperature compensation control is simultaneously implemented during the addition process, effectively offsetting the temperature drop in molten steel caused by the addition of cold diluents, maintaining the thermal balance of the refining system, and providing temperature assurance for the smooth operation of subsequent continuous casting processes.

[0012] The technical solution further defined in this invention is as follows: Furthermore, in the aforementioned steelmaking method for freely controlling the composition of molten steel in an LF refining furnace, the iron-based diluent comprises the following components by mass percentage: Carbon: 0.0027%, Silicon: 0.0043%, Manganese: 0.010%, Phosphorus: 0.0019%, Oxygen: 0.00778%, Nitrogen: 0.00631%, Aluminum: 0.0052%, Chromium: 0.005%, Nickel: 0.0072%, Copper: 0.0054%, Titanium: 0.0005%, Magnesium: 0.0012%, Molybdenum: 0.0001%, Vanadium: 0.00001%, Niobium: 0.0005%, Tantalum: 0.00493%, Hydrogen: 0.00002%, Boron: 0.0001%, Calcium: 0.0037%, Cobalt: 0.0029%, Lead: 0.0002%, Antimony: 0.0002%, Bismuth: 0.00005%, Tin: 0.001%, Arsenic: 0.0004%, Balance: Iron. The sum of the mass percentages of the above components is 100%.

[0013] Technically, this invention ensures the purity of the diluent by specifically limiting the iron-based diluent to industrial pure iron and setting strict content limits for its key impurity elements. This ensures that the dilution process only reduces the concentration of excessive elements without significantly changing the content of other controlled elements in the molten steel, thereby improving the predictability and stability of composition control.

[0014] In the aforementioned steelmaking method for freely controlling the composition of molten steel in an LF refining furnace, the target addition amount is calculated based on the following formula: , Among them, W d For the target amount added, W o For the current quality of the molten steel, C o C represents the current content of the element exceeding the standard. t The target content.

[0015] In terms of technical effects, this invention provides an accurate calculation formula based on the principle of mass conservation, which significantly improves the calculation accuracy of the target addition amount and reduces the number of repeated adjustments caused by calculation errors.

[0016] In the aforementioned steelmaking production method for freely adjustable LF refining furnace steel composition, temperature compensation control for the refining furnace is implemented, including: during the stage of preparing to add iron-based diluent, controlling the refining furnace to perform a heating operation to compensate for the heat loss generated during the addition process; after the addition of iron-based diluent is completed, controlling the refining furnace to perform a temperature recovery operation based on the difference between the real-time temperature and the target temperature of the refining furnace.

[0017] Technically, this invention employs a two-stage temperature compensation strategy—preheating before addition and dynamically restoring after addition—to proactively address the temperature drop caused by the heat absorption of the diluent. This prevents the molten steel temperature from deviating from the process window, ensuring that the melting state of the refining slag system and the kinetic conditions of the desulfurization and deoxidation reactions are not disrupted, thus guaranteeing the normal progress of the metallurgical reaction.

[0018] In the aforementioned steelmaking production method for freely controlling the composition of molten steel in an LF refining furnace, after controlling the addition of the target amount of iron-based diluent into the refining furnace, argon gas is blown into the refining furnace for stirring. The stirring duration is not less than 300 seconds to ensure that the molten steel and the iron-based diluent are mixed evenly, thus ensuring uniform composition of the molten steel and avoiding local component segregation or unmelted material residue. This provides a guarantee for the accuracy of subsequent component detection and the uniformity of molten steel quality.

[0019] In the aforementioned steelmaking production method for freely controlling the composition of molten steel in an LF refining furnace, obtaining the current composition data of the molten steel in the refining furnace includes: after performing a stirring operation on the molten steel, collecting molten steel samples from multiple preset locations in the refining furnace; obtaining initial composition data based on the molten steel samples, and cross-verifying the initial composition data with alloy addition record data and molten steel weight data to obtain the current composition data.

[0020] Technically, this invention, upon discovering that the steel composition exceeds the standard, immediately takes multiple samples for re-inspection after the steel has been thoroughly stirred. Through a mechanism of multi-point sampling and cross-verification of multi-dimensional data, it effectively eliminates false exceedance signals caused by uneven steel composition or measurement errors, ensuring the authenticity and reliability of the basic data upon which dilution calculations rely. It also prevents resource waste and production disruption caused by misoperation, verifies alloy addition records and steel quantity data, and confirms the types and amounts of exceedance elements, as well as the current temperature and remaining refining time of the steel. In the aforementioned steelmaking production method for freely controlling the composition of molten steel in an LF refining furnace, after controlling the addition of the target amount of iron-based diluent to the refining furnace, the method further includes: re-collecting molten steel samples to obtain verification composition data; if the content of the excessive element in the verification composition data is still greater than the target content, recalculating the supplementary addition amount based on the verification composition data, and controlling the addition of the supplementary amount of iron-based diluent to the refining furnace; if the composition meets the standard, raising the temperature to the target temperature according to the normal refining process to ensure smooth continuous casting. This invention establishes a closed-loop method for component verification and dynamic supplementation adjustment. When a single dilution does not fully meet the standard, it can quickly correct and perform supplementation based on the latest measured data, avoiding the need for whole-furnace re-judgment or re-firing due to a single inadequate control, thereby improving the final hit rate of component control and production efficiency.

[0021] In the aforementioned steelmaking production method for freely controlling the composition of molten steel in an LF refining furnace, when adding the target amount of iron-based diluent to the refining furnace, the iron-based diluent is added to the ladle of the refining furnace at a height below a preset threshold through a dedicated automated feeding system or overhead crane hoisting device, in order to control molten steel splashing.

[0022] The technical benefits include a dedicated hoisting period for pure iron, and the planned construction of a dedicated silo in the future to avoid conflicts over overhead crane usage. A dedicated pure iron storage area will be designated near the LF furnace operating area to ensure the supply of raw materials nearby and reduce transfer time. If a dedicated silo is built, automated feeding can be achieved, improving efficiency and reducing safety risks. By limiting the feeding method, this invention effectively controls the physical impact and splashing risks when cold solid materials are added to high-temperature molten steel, ensuring the safety of on-site operators and equipment, and reducing steel loss and environmental pollution caused by splashing.

[0023] The beneficial effects of this invention are: (1) Significantly improved component control efficiency: After adopting this invention, the time for handling excessive chromium content is shortened from more than 4 hours to less than 30 minutes. For example, in the case of an accident with excessive chromium content, the impact time after adopting this technology is no more than half an hour, and the continuous casting furnace can continue to operate normally without stopping casting.

[0024] (2) Wide process adaptability: This invention is applicable to the treatment of excessive levels of conventional elements such as C, Mn, Si, Cr, Ni, Mo, as well as residual elements such as P, Cr, B, Cu, and harmful elements. It has good compatibility with different steel types (such as bearing steel, alloy structural steel, cold heading steel, etc.) and overcomes the limitation of existing chemical removal methods that only target a single element.

[0025] (3) Low operational difficulty: The technical process is simple and easy to understand, and operators can master it after a short period of training, avoiding the risk of operational errors in traditional complex adjustment processes. For example, the problem of excessive chromium caused by alloy calculation errors can be quickly remedied by dilution.

[0026] (4) The direct economic benefits are significant. Taking a steel plant with an annual output of 4 million tons of steel as an example: ① Reduce losses from handling excess steel: Based on processing 1,000 tons of pure iron per year, this can avoid reclassifying / scrapping 20,000 tons of products (processing cost of 400 yuan per ton of steel), reducing losses by 8 million yuan; ② Reduced continuous casting interruptions by 24 times (twice a month), recovering a production loss of 17,000 tons (gross profit of 300 yuan per ton of steel) and increasing revenue by 5 million yuan; ③ Reduced the extra electricity consumption of LF refining by 72 hours (5000 kWh per hour, electricity price 0.6 yuan / kWh), saving 216,000 yuan in electricity costs; ④ Reduce electrode and refractory material consumption and overhead crane system costs by RMB 1.5 million; ⑤ Improve product qualification rate: The hit rate of steel composition control has increased from 98.5% to over 99.5%, and the reclassification rate of high value-added steel grades has been significantly reduced. Based on a price difference of 500 yuan per ton of high value-added steel, this will generate an additional revenue of over 10 million yuan per year.

[0027] The total direct economic benefits amount to 35.92 million yuan per year, which fully covers the pure iron procurement cost of 2 million yuan per year.

[0028] (5) Significant indirect economic benefits: ① Improved production system stability: Reduces accidents such as extended LF refining time and continuous casting interruption, improves furnace and machine matching efficiency, and is expected to generate indirect benefits of over 50 million yuan per year, including reduced losses from order delivery delays, increased production capacity due to improved equipment utilization, and reduced claims risks arising from quality disputes.

[0029] ② Enhanced brand reputation: Improved product quality and stability, increased customer satisfaction, help expand market share in the high-end market and enhance long-term market competitiveness.

[0030] This invention fundamentally avoids the risk of secondary pollution caused by impurities in traditional scrap steel dilution methods. It offers high precision and a high first-time hit rate in composition control. By simultaneously implementing refining furnace temperature compensation control during the addition process and coordinating with downstream continuous casting processes, it effectively maintains the thermal balance of the refining system and the continuity of furnace-machine connection. This prevents temperature runaway or production interruptions caused by composition control, thereby improving the stability and operational efficiency of the overall production system while ensuring steel quality. This invention also innovatively proposes an industrial pure iron dilution method for freely controlling the composition of molten steel. Essentially, it utilizes the extremely low impurity element content of industrial pure iron to reduce the concentration of excessive elements in the molten steel within the LF refining furnace through precise addition of industrial pure iron, achieving rapid composition control. The core logic is as follows: when a certain element in molten steel exceeds the standard, the required amount of industrial pure iron to be added is calculated based on the difference between the excess amount and the target composition. The extremely low content (close to zero) of that element in pure iron is used to dilute the concentration of molten steel, so that the composition of molten steel can reach the target requirements. The greater the difference between the composition of molten steel and the composition of pure iron, the more significant the dilution effect, and the efficient and free control of the composition can be achieved. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Example 1

[0033] This embodiment provides a steelmaking production method for freely controlling the composition of molten steel in an LF refining furnace. This method establishes an active dilution control backbone process for furnaces with excessive composition, aiming to solve the technical problems of traditional treatment methods easily introducing new impurities or disrupting production continuity. The method mainly includes the following steps: S101. Obtain the current composition data of molten steel in the refining furnace, and determine and verify whether the composition exceeds the standard; Specifically, data can be collected in real time using existing online composition analysis systems equipped in the refining furnace, or samples can be extracted using existing automatic samplers after the molten steel has been initially stirred and mixed uniformly, and then sent to the laboratory for spectral analysis. This ensures that the acquired data accurately reflects the overall chemical state of the molten steel before control, providing a reliable basis for subsequent precise dilution calculations. Current composition data not only includes the content values ​​of individual elements but also typically covers related process parameters such as steel temperature and weight, in order to comprehensively assess the state of the molten steel.

[0034] S102. Based on the presence of excessive elements in the current composition data, determine the target amount of iron-based diluent to be added. The target amount to be added is determined based on the current mass of the molten steel, the current content of the excessive elements, and the target content. Specifically, the iron-based diluent is a metal material with iron as the main matrix and controlled impurity content. In this embodiment, industrial pure iron is selected. The composition of industrial pure iron is limited to ensure the purity of the diluent itself. This ensures that while reducing the concentration of the target element, it will not introduce new harmful impurities into the molten steel or cause other controlled elements to exceed the standard. This avoids the secondary pollution risk common in traditional scrap steel dilution methods and accurately calculates the economic addition amount (it is necessary to take into account both dilution effect and cost control to avoid excessive addition).

[0035] S103. Control the amount of iron-based diluent added to the refining furnace according to the target amount; Specifically, after calculating the precise target addition amount, the corresponding weight of iron-based diluent is slowly added to the ladle of the refining furnace using existing automated feeding systems or manually assisted hoisting devices. This ensures a smooth addition process and avoids splashing of molten steel. Specifically, the iron-based diluent is added to the ladle of the refining furnace at a height below a preset threshold to control splashing. This step emphasizes precision; the actual addition amount should be as close as possible to the calculated target amount to ensure that the composition control effect meets expectations. In actual operation, continuous feeding or batch feeding modes can be selected according to on-site equipment conditions, but the total amount added must be controllable.

[0036] After controlling the addition of the target amount of iron-based diluent into the refining furnace, the process also includes controlling the blowing of argon gas into the refining furnace for stirring, with the stirring duration not less than 300 seconds, so that the molten steel and iron-based diluent are mixed evenly.

[0037] Compared to conventional alloying additives, industrial pure iron has a higher melting point (approximately 1538℃) and a relatively slower dissolution and diffusion rate in molten steel. If the stirring time is too short, two unfavorable situations can easily occur: first, the core of the high-melting-point pure iron block may not be fully melted before sampling and testing, leading to distorted compositional analysis results and misleading subsequent adjustments; second, even after melting, insufficient diffusion can result in a compositional concentration gradient within the ladle, potentially causing localized exceedances. A critical value of 300 seconds ensures both complete phase transformation and thermal equilibrium of the solid material and provides sufficient turbulent diffusion time to achieve macroscopic compositional homogenization.

[0038] S104. During the process of adding iron-based diluent, temperature compensation control is performed on the refining furnace, specifically including: during the preparation stage of adding iron-based diluent, controlling the refining furnace to perform a heating operation to compensate for the heat loss generated during the addition process; after the addition of iron-based diluent is completed, controlling the refining furnace to perform a temperature recovery operation based on the difference between the real-time temperature and the target temperature of the refining furnace.

[0039] Specifically, since iron-based diluents are typically added to molten steel in solid form at room temperature or low temperature, their melting and heating processes absorb a large amount of heat. Without intervention, this can easily lead to a significant drop in steel temperature, thereby disrupting the fluidity of the refining slag system and the thermodynamic conditions required for metallurgical reactions such as desulfurization and deoxidation. Therefore, this step requires simultaneous temperature compensation control during the addition process. This involves actively offsetting heat loss caused by the addition of cold materials by adjusting electrode heating power, combustion heating, or other heating methods. This simultaneous compensation mechanism is not simply a post-heating process, but rather a dynamic thermal balance management throughout the addition process. It ensures that the steel temperature remains within a suitable process window, guaranteeing the normal progress of the metallurgical reaction while avoiding the risk of continuous casting interruption due to excessively low temperatures or energy waste and refractory corrosion due to excessive heating.

[0040] Temperature compensation control and the aforementioned argon blowing and stirring are not executed in isolation, but rather form a tightly coupled process synergy system. During stirring, the upward movement of argon bubbles not only promotes component mixing but also enhances forced convection heat transfer within the molten steel. This allows the preheating heat from the preparation stage to be transferred more quickly to the bottom and edge cold zones of the ladle, and provides a uniform temperature field basis for post-stress recovery, avoiding heating misjudgments caused by inaccurate local temperature measurements. Conversely, a stable temperature field maintains the good fluidity of the slag and the low viscosity of the molten steel, creating excellent kinetic conditions for argon stirring and preventing the risk of stirring dead zones or slag entrapment due to excessively low temperatures. The temporal overlap and functional complementarity of these two processes jointly ensure the efficiency and safety of the component control process, demonstrating the technical advantages of this application in multi-physics field synergistic control.

[0041] This invention constructs a complete method for actively controlling excessive component levels through the synergistic implementation of the four core steps described above. This method achieves precise addition of diluent without introducing new impurities, utilizing the principle of mass conservation, and maintains system thermal balance through synchronous temperature compensation. This lays the technical foundation for further refining material standards, optimizing calculation formulas, coordinating stirring processes, and linking downstream processes in subsequent dependent embodiments.

[0042] This embodiment also provides a system for the steelmaking production method of finely controlling the composition of molten steel in the refining furnace as described above. As the hardware carrier of the method, the system is usually integrated into the distributed control system (DCS) or programmable logic controller (PLC) of the refining furnace, and establishes a real-time communication connection with field sensors and actuators. It includes a composition data acquisition module for acquiring the current composition data of molten steel in the refining furnace; a dilution calculation module for determining the target amount of iron-based diluent to be added in response to the presence of excessive elements in the current composition data, the target amount of which is determined based on the current mass of molten steel, the current content of the excessive elements, and the target content; a feeding control module for controlling the addition of the target amount of iron-based diluent to the refining furnace; and a temperature compensation control module for performing temperature compensation control for the refining furnace during the addition of iron-based diluent. By modularly integrating composition acquisition, precise calculation, automatic feeding, and temperature compensation functions, the system realizes the fully automated and intelligent execution of the refining furnace molten steel composition exceeding the standard control process, ensuring the stable implementation and efficient operation of the aforementioned method in actual industrial production.

[0043] Specifically, the composition data acquisition module is not merely a data receiving interface, but a data acquisition and preprocessing unit bound to the on-site testing hardware. This module connects to existing systems such as direct-reading spectrometers, automatic samplers, ladle weighing sensors, and alloy feeding recording systems via an industrial bus, enabling real-time reading of raw data such as the chemical analysis values, net weight of molten steel, and historical alloy input amounts. During acquisition, this module is also configured to perform data cross-verification logic, automatically comparing spectral analysis results with material balance calculation values. When a deviation exceeds a preset range, it automatically marks the data as abnormal and triggers a re-inspection command, ensuring the accuracy and reliability of the composition data input for subsequent calculations. The dilution calculation module internally stores a database of iron-based diluent composition and a calculation model built based on the principle of mass conservation. Upon receiving an over-limit confirmation signal from the composition data acquisition module, the module automatically retrieves the content parameters of the corresponding batch of iron-based diluent from the database. Combining this with the real-time molten steel quality and the target composition setting, it calculates the precise target addition amount, eliminating the uncertainty of manual estimation. The feeding control module serves as a bridge between digital decision-making and physical execution. It is directly connected to the frequency converter of the vibrating feeder, belt scale, or overhead crane hoisting device in the dedicated silo. This module receives the target addition amount instruction from the dilution calculation module and converts it into specific equipment control parameters, such as adjusting the vibration frequency and running time of the feeder to achieve quantitative feeding. The temperature compensation control module is connected to thermal actuators such as the electrode lifting regulator, transformer gear switch, and bottom-blown argon solenoid valve. This module is configured to monitor the working status signal of the feeding control module. Once it detects the status indicator of preparation or in progress of addition, it automatically starts the preset temperature compensation program. For example, the electrode power is automatically increased to the preheating level before addition, and the heating time and stirring intensity are dynamically adjusted according to the temperature difference value fed back by the real-time temperature measuring thermocouple after addition. This module achieves automation and precision in thermal balance management by tightly coupling the temperature control logic and the feeding action in sequence, avoiding the lag and arbitrariness of manual temperature adjustment, and ensuring that the molten steel is always within the appropriate metallurgical temperature range throughout the entire process.

[0044] The system uses existing modules, which interact with each other via high-speed industrial Ethernet or fieldbus, forming a complete information loop from perception and decision-making to execution. This system-level architecture supports the efficient implementation of the component excess control method, significantly improving the stability of the production process and the consistency of product quality. Example 2

[0045] To more clearly illustrate the application effect and operability of the technical solution of this application in actual industrial production, the following detailed explanation is based on the scenario of controlling excessive chromium content in the LF refining furnace of a steel plant.

[0046] Because the previous ladle used Cr-containing steel, the next steel grade has requirements for residual Cr, resulting in high Cr content after electric arc furnace smelting.

[0047] This was the second heat of steel, and the tundish could only predict the interruption of pouring, leading to a furnace head accident. This accident affected production, increased the amount of gas used for baking in the tundish, increased the turnover load of the overhead crane, increased refractory material consumption, and resulted in a significant loss of heat from the molten steel.

[0048] The electric furnace has two machines, so the impact on the overall production organization is not significant.

[0049] Converter production requires timely delivery of qualified molten steel to the next process.

[0050] The method of the present invention specifically includes: Step (1): The system first executes the composition data acquisition and verification process. After the molten steel is initially stirred and mixed evenly, samples are collected from multiple preset locations at the center and edge of the ladle using an automatic sampler for spectral analysis. The test results show that the chromium content in the representative sample of this heat significantly exceeds the upper limit of the target steel grade. At the same time, the system automatically retrieves the alloy addition record and ladle weighing data for cross-verification, confirming that no chromium-containing alloys were added during this period and that there were no abnormal fluctuations in the weight of the molten steel. This eliminates detection errors or false signals and confirms the fact that the chromium content exceeds the standard.

[0051] Step (2): For confirmed chromium exceeding the standard, the dilution calculation program is immediately started to calculate the target addition amount.

[0052] The iron-based diluent used in this case is industrial pure iron. Upon arrival at the warehouse, its measured composition met stringent purity requirements. The iron-based diluent, by mass percentage, includes the following components: carbon: 0.0027%, silicon: 0.0043%, manganese: 0.010%, phosphorus: 0.0019%, oxygen: 0.00778%, nitrogen: 0.00631%, aluminum: 0.0052%, chromium: 0.005%, nickel: 0.0072%, copper: 0.0054%, titanium: 0.0005%, magnesium: 0.0 The composition is as follows: 0.12% molybdenum, 0.0001% vanadium, 0.00001% niobium, 0.0005% tantalum, 0.00493% hydrogen, 0.00002% boron, 0.0001% calcium, 0.0037% cobalt, 0.0029% lead, 0.0002% antimony, 0.0002% bismuth, 0.00005% tin, 0.001% arsenic, and the balance is iron. The sum of the mass percentages of all the above components is 100%. Based on this measured data, the system will calculate the current mass W of the molten steel. o Current chromium content C o Target content C t Substitute into the correction formula Perform calculations to accurately determine the target amount W of industrial pure iron to be added. d The amount is 3 tons, which avoids the risk of overfeeding.

[0053] Step (3): Before the addition operation, temperature compensation and material feeding control are carried out in tandem. On the one hand, the refining furnace control system performs a preheating operation in advance, raising the temperature of the molten steel to a preheating reserve value slightly higher than the conventional outlet temperature; on the other hand, the system sends a rhythm adjustment command to the control system of the continuous casting process, instructing it to reduce the casting speed to match the expected extended refining processing time, ensuring the continuity of furnace and machine connection. Subsequently, the overhead crane hoisting device smoothly adds 3 tons of industrial pure iron into the ladle at a height below the preset threshold, effectively controlling the splashing of high-temperature molten steel and ensuring on-site operation safety. After the addition is completed, the system immediately controls the bottom blowing argon system to perform strong stirring, with the duration set to more than 300 seconds, to ensure that the high melting point industrial pure iron is completely melted and the chromium element diffuses evenly in the molten steel. At the same time, argon stirring is used to enhance convective heat transfer, and electrode heating is used to perform temperature recovery operation, so that the temperature of the molten steel accurately returns to the continuous casting target temperature window.

[0054] Step (4): After stirring, the system re-collected the molten steel sample to obtain verification composition data. The test results showed that the chromium content had dropped to within the target specification range, and other controlled elements did not fluctuate abnormally, achieving the first-time dilution hit rate. The entire control process, from the discovery of exceeding the standard to the composition meeting the standard and leaving the station, took less than 30 minutes. Compared with the traditional re-judgment or remelting method, this batch not only avoided the potential loss of 8 million yuan caused by the re-judgment of approximately 20,000 tons of products, but also successfully prevented the continuous casting interruption accident, recovered the production loss, and reduced additional power consumption and refractory consumption.

[0055] This practical experience fully demonstrates that the control method provided in this application, through the organic combination of low-impurity dilution medium, accurate mass conservation calculation and multi-process collaborative control, can efficiently solve the problem of excessive components without introducing new impurities, and significantly improve the stability and economic benefits of the production system.

[0056] Currently, both domestic and international steel companies primarily rely on a "prevention-oriented, reactive" approach to control composition in LF refining. Domestic technologies focus on raw material classification and control, alloy yield model prediction, and strengthened operational procedures, but lack proactive control methods for exceeding standards. When using ordinary scrap steel for dilution, composition fluctuations can easily introduce new impurities. While advanced international technologies have achieved precise closed-loop control through digital batching and online detection, they often resort to converter remelting or recasting lower-grade steel for furnaces with excessive composition, resulting in high processing costs and significant production interruption risks. Existing technologies suffer from drawbacks: limited handling methods after exceeding composition standards, high economic and time costs, inability to achieve rapid and stable control of excessive elements, and potential disruption to furnace-machine continuity. This invention overcomes technical limitations and proposes a method to solve the technical problem of economically and efficiently handling excessive components during LF refining, ensuring the stable and smooth operation of the entire steelmaking system. Addressing the issue of excessive elements (C, Mn, Si, Cr, Ni, Mo, P, Cu, B, etc.) during LF refining, this invention adds high-purity industrial pure iron. Utilizing the extremely low content of impurity elements, the concentration of excessive elements in the molten steel is physically diluted, achieving rapid component reversion. Existing technologies mostly employ chemical methods to remove excessive elements, while this invention dilutes the concentration of each element in the molten steel by adding high-purity industrial pure iron. This is a "concentration dilution" logic; the total amount of excessive elements is not reduced, but their concentration ratio in the molten steel is lowered due to the addition of pure iron. Furthermore, this method is universally applicable to the control of multiple elements and various steel grades.

[0057] In addition to the embodiments described above, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A steelmaking method for freely controlling the composition of molten steel in an LF refining furnace, characterized in that, include Obtain the current composition data of the molten steel in the refining furnace; Based on the presence of excessive elements in the current component data, the target amount of iron-based diluent to be added is determined. Control the addition of the target amount of the iron-based diluent into the refining furnace; During the addition of the iron-based diluent, temperature compensation control is performed for the refining furnace.

2. The steelmaking method for freely adjustable LF refining furnace steel composition according to claim 1, characterized in that: The iron-based diluent comprises the following components by mass percentage: Carbon: 0.0027%, Silicon: 0.0043%, Manganese: 0.010%, Phosphorus: 0.0019%, Oxygen: 0.00778%, Nitrogen: 0.00631%, Aluminum: 0.0052%, Chromium: 0.005%, Nickel: 0.0072%, Copper: 0.0054%, Titanium: 0.0005%, Magnesium: 0.0012%, Molybdenum: 0.0001%, Vanadium: 0.00001%, Niobium: 0.0005%, Tantalum: 0.00493%, Hydrogen: 0.00002%, Boron: 0.0001%, Calcium: 0.0037%, Cobalt: 0.0029%, Lead: 0.0002%, Antimony: 0.0002%, Bismuth: 0.00005%, Tin: 0.001%, Arsenic: 0.0004%, Balance: Iron. The sum of the mass percentages of the above components is 100%.

3. The steelmaking method for freely controlling the composition of molten steel in an LF refining furnace according to claim 1, characterized in that: The target amount added is calculated based on the following formula: ， Among them, W d For the target amount added, W o C represents the current mass of the molten steel. o C represents the current content of the element exceeding the standard. t The target content.

4. The steelmaking method for freely controlling the composition of molten steel in an LF refining furnace according to claim 1, characterized in that: Performing temperature compensation control for the refining furnace includes: During the preparation stage for adding the iron-based diluent, the refining furnace is controlled to perform a heating operation to compensate for the heat loss generated during the addition process; After the iron-based diluent is added, the refining furnace is controlled to perform a temperature recovery operation based on the difference between the real-time temperature and the target temperature.

5. The steelmaking method for freely adjustable LF refining furnace steel composition according to claim 1, characterized in that: After the target amount of the iron-based diluent is added to the refining furnace, argon gas is blown into the refining furnace for stirring. The stirring time is not less than 300 seconds, so that the molten steel and the iron-based diluent are mixed evenly.

6. The steelmaking method for freely adjustable LF refining furnace steel composition according to claim 1, characterized in that: Obtain the current composition data of the molten steel in the refining furnace, including: After the molten steel is stirred, molten steel samples are collected from multiple preset locations inside the refining furnace; The initial composition data is obtained based on the molten steel sample, and the initial composition data is cross-verified by combining the alloy addition record data and the molten steel weight data to obtain the current composition data.

7. The steelmaking method for freely adjustable LF refining furnace steel composition according to claim 1, characterized in that: After controlling the addition of the target amount of the iron-based diluent into the refining furnace, the process further includes: The molten steel sample was re-collected to obtain verification composition data; If the content of the excessive element in the verification component data is still greater than the target content, the amount of supplementary addition is recalculated based on the verification component data, and the amount of iron-based diluent added to the refining furnace is controlled. If the composition meets the standards, the temperature is raised to the target temperature according to the normal refining process to ensure smooth continuous casting.

8. The steelmaking method for freely adjustable LF refining furnace steel composition according to claim 1, characterized in that: When adding the target amount of the iron-based diluent into the refining furnace, the iron-based diluent is added to the ladle of the refining furnace at a height below a preset threshold by feeding from a dedicated silo or by overhead crane, in order to control molten steel splashing.

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