A method for measuring and calculating the amount of slag discharged from a converter

Abstract

This invention relates to the field of iron and steel smelting technology, specifically providing a method for calculating the amount of slag discharged during converter tapping. The invention obtains corrected endpoint data for the calculated heat based on historical heat-related information, calculated heat-related information, TSO detection results from the auxiliary lance at the blowing endpoint of historical heats, and slag analysis results from historical heats. A secondary database is established through data classification. Then, CFD simulation is used to obtain the slag density and the slag-to-steel ratio in the axial direction of the steel flow. Infrared slag discharge detection is used to obtain the tapping spout life, molten steel flow rate, and the slag-to-steel ratio in the radial direction of the steel flow. This enables continuous calculation of the amount of slag discharged during the calculated heat and yields the total amount of slag discharged, achieving efficient, intelligent, online real-time measurement and data application of converter tapping slag discharge.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, specifically to a method for calculating the amount of slag discharged during converter tapping. Background Technology

[0002] Steel cleanliness is an important indicator for measuring the level of control of non-metallic inclusions, gas content, and harmful elements in molten steel, directly affecting the mechanical properties, processing performance, and durability of steel. The cleanliness requirements vary significantly depending on the intended use of the steel, and one of the core indicators of cleanliness is the presence of non-metallic inclusions (oxides, sulfides, etc.).

[0003] Slag-blocking tapping refers to the operation of releasing molten steel into the ladle (steel ladle) after the converter blowing process or the electric arc furnace oxidation melting process, leaving the oxidized slag inside the furnace. Separating the oxidized slag from the molten steel during tapping is a requirement of ladle refining. Secondary refining in the ladle is best carried out under reducing conditions. Using slag-blocking tapping to avoid slag carryover is a crucial guarantee for improving the ladle refining effect. During tapping, as the molten steel level drops, when the molten steel depth falls below a certain critical value, a funnel-shaped converging vortex forms above the taphole. Some slag flows out of the taphole before all the molten steel has been tapped, which is the fundamental reason for incomplete slag-steel separation. Additionally, excessively rapid furnace shaking can cause some slag to gush out of the furnace mouth; however, this can be avoided with careful operation. High-temperature, high-oxidizing slag from the converter's final stage entering the ladle easily causes phosphorus reversion, reduces the metallurgical effect of ladle refining, and lowers alloy yield and steel cleanliness. Therefore, in order to maximize the effect of ladle refining, improve the quality of the billet, and control the stability of the steel composition, slag blocking operations must be carried out during tapping.

[0004] Slag-blocking steelmaking technology was mainly developed to address slag discharge from converging vortices. Various methods exist, including slag-blocking balls, slag-blocking plugs, high-pressure air slag blocking, slag-blocking valves, and slag discharge signal detection.

[0005] Different methods have their own advantages and disadvantages. For example, slag-blocking balls have a simple structure but unstable effects, while sliding plate slag blocking is more expensive but more precise. However, regardless of the method used, during the tapping process, as the molten steel level drops, when the molten steel depth falls below a certain critical value, a funnel-shaped converging vortex will form above the taphole. This causes slag entrapment in the later stages of tapping, with some slag flowing out of the taphole before all the molten steel has been tapped. This is the root cause of the incomplete separation of slag and steel. In this situation, if slag blocking is performed too early, or tapping is stopped, some molten steel will remain in the converter, resulting in waste and affecting metal yield. Conversely, if it is performed too late, some steel slag will enter the ladle with the molten steel, causing contamination of the molten steel and affecting the refining effect.

[0006] The specific slag-blocking method should be selected based on the equipment parameters, process requirements, and product grade, and a thorough understanding of the various calculation methods is required to determine the most suitable approach. Therefore, accurate and real-time calculation of the amount of slag discharged from the converter is of great significance for improving the cleanliness of the steel. Summary of the Invention

[0007] This invention aims to completely solve the industry pain points of traditional slag quantity measurement methods, which are lagging, offline, and inaccurate, by constructing a systematic solution that integrates "intelligent prediction, dynamic monitoring, and closed-loop optimization". This invention is used to detect the amount of slag discharged at the tapping spout during the later stages of converter steelmaking and to calculate the amount of slag discharged into the ladle. Based on historical heat information, calculated heat information, and the TSO detection results of the auxiliary lance at the blowing endpoint of historical heats, as well as the slag analysis results of historical heats, the corrected endpoint data for the calculated heat is obtained. A secondary database is established through data classification. Then, CFD simulation is used to obtain the slag density and the slag-to-steel ratio in the axial direction of the steel flow. Infrared slag discharge detection is used to obtain the tapping spout life, molten steel flow rate, and the slag-to-steel ratio in the radial direction of the steel flow. This enables continuous calculation of the slag discharge for the calculated heat and obtains the total slag discharge. It achieves efficient, intelligent, and online real-time measurement and data application of converter tapping slag discharge, meeting the needs for intelligent, rapid, and low-cost detection in the steelmaking process. It facilitates the analysis of the molten steel's state during subsequent historical queries and provides core data support for subsequent refining treatment of molten steel, precise control of alloy composition, and refined and intelligent control of the steelmaking process. This is beneficial for improving molten steel quality and process production efficiency, reducing alloy costs, and ensuring efficient, stable, and smooth production.

[0008] A method for calculating the amount of slag discharged during converter tapping includes: S1. Calculate theoretical endpoint data: Collect data on historical furnace information and calculated furnace information to establish a historical furnace database; calculate the theoretical endpoint data for each historical furnace based on material balance and heat balance. The theoretical endpoint data includes the theoretically calculated value of the final slag weight G. 渣-理论 Theoretical calculation value W of the main component content in the final residue i--理论 Theoretical calculated value T of molten steel temperature at the end of blowing 钢水-理论 Theoretical calculated value T of slag temperature at the end of blowing 炉渣-理论 ; S2. Corrected theoretical endpoint data: Based on the TSO test results of the auxiliary lance at the blowing endpoint of historical furnaces and the slag test results of historical furnaces, the corrected endpoint data of the calculated furnace is obtained by calculation and correction through a symmetrical connection neural network. The corrected endpoint data includes the final residue weight correction value G. 渣-修正 Correction value W for the content of major components in the final residue i--修正 Correction value for slag temperature at the end of blowing process T炉渣-修正 Correction value for molten steel temperature at the end of blowing process (T) 钢水-修正 ; S3. Data classification and establishment of a secondary database: Based on the relevant information of historical furnaces, the relevant information of calculated furnaces, the TSO test results of the auxiliary lance at the blowing endpoint of historical furnaces, the slag test results of historical furnaces, and the corrected endpoint data, the data are classified according to the principle of similarity or similarity to establish a secondary database, and the calculated furnaces are categorized. S4, CFD simulation of slag density under different conditions: S401. Establish a geometric model: Establish a three-dimensional geometric model of the converter body and divide it into computational meshes; S402. Define the furnace environment as multiphase flow, which includes at least two phases: molten steel and slag. S403. Set physical property parameters: The chemical composition and temperature of the secondary database of the calculation furnace are transferred to the thermodynamic software through the CFD software. The thermodynamic software then returns physical property parameters, which are used to calculate the kinetic parameters for flow calculation, thereby calculating the steel-slag ratio in the axial direction of the steel flow (i.e., the steel-slag ratio of the molten steel section parallel to the flow direction at the tapping outlet). Preferably, the dynamic parameters include molten steel flow velocity and cross-sectional area; Preferably, the thermodynamic software is the FactSage thermodynamic database; Preferably, the physical property parameters include slag density; S5. Infrared slag detection during steel tapping: S501. Acquiring image and temperature data: During the steel tapping process, the infrared thermal imager automatically tracks and captures images of the steel flow at the tapping spout, obtaining continuous image data and real-time temperature data of the molten steel. S502. Image data processing: Calculate the tapping port life (steel flow radius) and molten steel flow velocity in the tapping port at different time periods during the tapping process of the heat. Based on different temperature thresholds, distinguish the far-infrared bands of the infrared radiation coefficients of molten steel and slag to obtain the steel-slag ratio in the radial direction of the steel flow (i.e., the steel-slag ratio on the cross section perpendicular to the steel flow axis). S503, Continuous calculation of slag discharge rate: Based on the steel slag ratio in the axial direction calculated in step S403 and the steel slag ratio in the radial direction calculated in step S502, the instantaneous steel slag ratio of the entire steel flow is calculated.

[0009] Based on the instantaneous steel-slag ratio of the overall steel flow at different time periods during the steel tapping process of the calculation heat, the tapping outlet life (steel flow radius), the steel flow velocity in the tapping outlet during tapping, and the slag density simulated by CFD software, the slag discharge amount for this heat is continuously calculated.

[0010] Furthermore, based on the slag discharge setting conditions and process requirements, when the infrared slag discharge detection amount reaches the set value, the sliding plate is closed, slag blocking is completed, and steel tapping ends. The total slag discharge amount after steel tapping is obtained based on continuous calculation results, which are accumulated from the continuous calculation results.

[0011] The historical furnace charge information and calculated furnace charge information include the conditions of molten iron entering the furnace, the conditions of scrap steel, the conditions of slag-forming auxiliary materials, coolant, and slag-forming agent, the converter bottom blowing process parameters, the converter lining life, and the oxygen consumption of converter blowing.

[0012] Furthermore, the conditions for feeding molten iron into the furnace include the composition, temperature, weight, and amount of slag. The scrap steel conditions include the scrap steel structure type, weight, and scrap steel addition ratio; The conditions for the slag-forming auxiliary materials, coolants, and slag-reducing agents include their types, components, and amounts added.

[0013] The TSO test results of the secondary gun at the end of the blowing process include the end temperature, carbon content, and oxygen content.

[0014] In step S4, the CFD simulation calculates the corresponding dynamic slag density, which is closer to reality, based on various smelting conditions (steel composition, slag-forming materials, temperature, etc.) in the secondary database, rather than the empirical value in the user manual, thereby fundamentally improving the accuracy of the subsequent calculation model.

[0015] In step S401, the computational domain is decomposed into multiple topologically shaped sub-regions, and a structured mesh is generated for each sub-region using a sweeping method to achieve the computational mesh division of the molten pool and tapping port of the converter; for regions where a pure hexahedral mesh structure cannot be generated, an unstructured mesh (i.e., a polyhedral mesh) is used.

[0016] In step S403, slag density is not a fixed constant, but rather strongly depends on its chemical composition (such as the content of CaO, SiO2, FeO, etc.), temperature, and the presence of bubbles (foaming). In CFD simulations, slag density is typically treated as a property that varies with conditions and location. By coupling the CFD software with the FactSage thermodynamic database, the CFD program transmits the chemical composition and temperature corresponding to the same or similar historical furnaces from the secondary database to the thermodynamic software. The thermodynamic software then returns accurate physical properties such as density and viscosity, which the CFD then uses for flow calculations.

[0017] In step S403, the CFD software simultaneously calculates the slag density in each grid cell while solving the entire flow field, thus ultimately obtaining the density distribution field of the slag within the entire converter and the taphole. This reveals the density differences at different locations, including density variations caused by temperature inhomogeneity or compositional segregation. Combined with the secondary database conditions, the density distribution fields corresponding to various secondary database conditions are simulated.

[0018] This invention goes beyond a single measurement technology innovation. By providing a precise, online solution for a key process parameter, it links and optimizes upstream and downstream processes. While improving quality, reducing costs, and ensuring smooth operation, it provides a practical technical path for the intelligent development of the steel industry, and has high engineering practical value and industry promotion significance.

[0019] This invention fundamentally changes the paradigm of measuring and controlling slag discharge during converter tapping. Its value lies not only in the single measurement stage but also in its impact on the quality, cost, and efficiency of the entire steelmaking production system. Its beneficial effects are specifically reflected in the following aspects: 1. At the measurement level, this invention achieves a leap from "estimation" to "precision calculation" and from "post-event" to "real-time." Traditional methods rely on manual experience, offline sampling, or tracers, which suffer from problems such as lag, large errors, and high costs. This invention dynamically predicts the precise density of slag before tapping by combining material balance, neural networks, and CFD simulation. Combined with real-time monitoring using infrared technology during tapping, it constructs an online calculation model based on multi-source data fusion. This transforms the acquisition of slag quantity from a rough analytical value obtained tens of minutes later into a high-precision dynamic data stream generated in real-time during tapping, enabling immediate process intervention.

[0020] 2. At the quality control level, a robust data-driven defense has been established to enhance the purity of molten steel. Accurate and timely slag discharge data is crucial for controlling phosphorus and sulfur reversion and inclusion contamination in molten steel. Refining processes (such as LF furnaces) can use this data to scientifically and quantitatively formulate top slag modification plans and alloy addition strategies, rather than relying on guesswork. This effectively avoids over- or under-treatment due to unclear slag discharge amounts, stabilizing the chemical composition and cleanliness of the molten steel from the source, and significantly improving the consistency and reliability of the final product.

[0021] 3. In terms of economic costs, significant cost reduction and efficiency improvement have been achieved. The benefits are twofold: First, it directly reduces alloy costs. Precise knowledge of molten steel conditions and slag conditions allows for the optimization of the addition of deoxidizers and alloy materials to the theoretical minimum, avoiding waste of valuable alloys. Second, it improves overall efficiency by stabilizing operations and reducing production anomalies. For example, problems such as prolonged refining time and process failures caused by excessive slag addition will be greatly reduced, ensuring a smooth and efficient production process and improving equipment utilization and capacity.

[0022] 4. At the level of technological evolution, this invention has driven the transformation and upgrading of steelmaking production towards digitalization and intelligence. It constructs a complete data closed loop of "perception-prediction-decision-optimization." The slag discharge amount for each heat of steel and its related full-process data (such as furnace charging conditions, blowing parameters, and tapping status) are automatically recorded and analyzed, forming a valuable process knowledge base. This not only facilitates quality traceability and problem diagnosis but also enables continuous optimization of converter blowing endpoint control and tapping operation modes through historical data mining. This allows the entire production process to possess the ability for continuous self-learning and improvement, representing the core direction of modern lean manufacturing and industrial intelligence. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating a method for calculating the amount of slag discharged during steel tapping in a converter. Detailed Implementation

[0024] A method for calculating the amount of slag discharged during converter tapping, illustrated in the following diagram: Figure 1 As shown, it includes: S1. Calculate the theoretical endpoint data: Data was collected on historical and calculated furnace information to establish a database. Material balance calculations were then used to determine the theoretical final slag weight G for each furnace. 渣-理论 Theoretical calculation value W of the main component content in the final residue i--理论 The theoretical calculated value T of the molten steel temperature at the end of the blowing process was obtained from the heat balance calculation. 钢水-理论 Theoretical calculated value T of slag temperature at the end of blowing 炉渣-理论 .

[0025] Historical furnace charge information and calculated furnace charge information include molten iron conditions (molten iron composition, temperature, weight, slag quantity, etc.), scrap steel conditions (scrap steel structure type, weight, scrap steel addition ratio, etc.), slag-forming auxiliary materials, coolant, and slag-forming agent conditions (type, composition, and addition amount), converter bottom blowing process parameters, converter lining life, and converter blowing oxygen consumption.

[0026] S2, Correction of theoretical endpoint data: The results of TSO testing (endpoint temperature, carbon content, oxygen content) at the final blowing point of the corresponding historical furnace, the slag test results, and the theoretically calculated final slag weight G 渣-理论 Theoretical calculation value W of the main component content in the final residue i--理论 Theoretical calculated value T of molten steel temperature at the end of blowing 钢水-理论 Theoretical calculated value T of slag temperature at the end of blowing process 炉渣-理论 By performing corresponding calculations and corrections using a symmetric connection neural network, the corrected final slag weight value G for the calculated furnace batch is obtained. 渣-修正 Correction value W for the content of major components in the final residue i--修正 Correction value for slag temperature at the end of blowing process T 炉渣-修正 Correction value for molten steel temperature at the end of blowing process (T) 钢水-修正 .

[0027] S3. Data classification and establishment of a secondary database. The historical furnace information, calculated furnace information, TSO test results of the auxiliary lance at the blowing endpoint of the historical furnace, slag test results and corrected endpoint data of the historical furnace are classified according to the principle of being the same or similar, and a secondary database is established.

[0028] S4 and CFD simulations were used to determine the slag density under different conditions. CFD simulation calculates the corresponding dynamic slag density, which is closer to reality, based on various smelting conditions (steel composition, slag-forming materials, and temperature) in the secondary database, rather than the empirical values ​​in the user manual, thus fundamentally improving the accuracy of subsequent calculation models.

[0029] CFD simulations achieve coupled calculations of multiphase flow, heat transfer, and chemical reaction processes within the furnace by numerically solving a set of partial differential equations consisting of mass, momentum, and energy conservation equations. The calculation logic for slag density is as follows.

[0030] S401. Establishing a geometric model: First, establish an accurate three-dimensional geometric model of the converter body and divide it into computational meshes.

[0031] When dealing with the complex geometry of the converter molten pool and tapping area, the computational domain can be decomposed into multiple sub-regions with simple topological shapes. For each sub-region, a structured mesh can be generated using a sweeping method. However, a pure hexahedral mesh cannot be generated for the tapping area. Therefore, a block partitioning strategy, i.e., using unstructured meshes in complex areas, is also an effective compromise.

[0032] S402. Define a multiphase flow system: Define the furnace environment as a multiphase flow, which includes at least two phases: molten steel and slag.

[0033] S403. Setting Physical Property Parameters: Slag density is not a fixed constant, but strongly depends on its chemical composition (such as the content of CaO, SiO2, FeO, etc.), temperature, and the presence of bubbles (foaming). In CFD simulations, slag density is usually treated as a property that varies with conditions and location. The CFD software is coupled with the FactSage thermodynamic database: the CFD program transmits the chemical composition and temperature from the secondary database of the heat to the thermodynamic software (FactSage thermodynamic database), which then returns precise density parameters. The CFD then uses these parameters for flow calculations to obtain the molten steel velocity and cross-sectional area, thereby calculating the slag-to-steel ratio in the axial direction (i.e., the slag-to-steel ratio of the molten steel cross-section parallel to the flow direction at the taphole).

[0034] S5. Infrared slag detection during steel tapping process During the tapping process, an infrared thermal imager automatically tracks and captures images of the steel flow at the tapping spout, obtaining continuous image data and real-time temperature data of the molten steel.

[0035] Image data processing: The far-infrared bands of the infrared radiation coefficients of molten steel and steel slag are very different. The two are distinguished according to different temperature thresholds, so as to obtain the steel slag ratio in the radial direction of the steel flow (i.e. the steel slag ratio on the cross section perpendicular to the steel flow axis).

[0036] Based on the steel slag ratio in the axial direction calculated in step S403 and the steel slag ratio in the radial direction calculated in step S502, the instantaneous steel slag ratio of the entire steel flow is calculated.

[0037] During the specific tapping process of a particular heat, based on the images of the steel flow at the tapping spout automatically tracked and continuously captured by the infrared thermal imager, real-time temperature data, and image processing results, combined with the instantaneous steel-slag ratio of the overall steel flow at different time points during the tapping process of this heat, the lifespan of the tapping spout (size of the steel flow radius), the steel flow velocity in the tapping spout during tapping, and the slag density simulated by CFD software, the slag discharge amount for this heat is continuously calculated.

[0038] S6. According to the slag discharge setting conditions and process requirements, when the infrared slag discharge detection amount reaches the set value, close the slide plate, complete the slag blocking, and end the steel tapping.

[0039] S7. Based on the continuous calculation results, the total slag discharge amount after steel tapping is obtained. The total slag discharge amount for a specific heat cycle is obtained by summing the continuous calculation results.

Claims

1. A method for calculating the amount of slag discharged during converter tapping, characterized in that, include: S1. Calculate theoretical endpoint data: Collect data on historical furnace information and calculated furnace information to establish a historical furnace database; calculate the theoretical endpoint data for each historical furnace based on material balance and heat balance. The theoretical endpoint data includes the theoretically calculated value of the final slag weight G. 渣-理论 Theoretical calculation value W of the main component content in the final residue i--理论 Theoretical calculated value T of molten steel temperature at the end of blowing 钢水-理论 Theoretical calculated value T of slag temperature at the end of blowing 炉渣-理论 ; S2. Corrected theoretical endpoint data: Based on the TSO test results of the auxiliary lance at the blowing endpoint of historical furnaces and the slag test results of historical furnaces, the corrected endpoint data of the calculated furnace is obtained by calculation and correction through a symmetrical connection neural network. The corrected endpoint data includes the final residue weight correction value G. 渣-修正 Correction value W for the content of major components in the final residue i--修正 Correction value for slag temperature at the end of blowing process T 炉渣-修正 Correction value for molten steel temperature at the end of blowing process (T) 钢水-修正 ; S3. Data classification and establishment of a secondary database: Based on the relevant information of historical furnaces, the relevant information of calculated furnaces, the TSO test results of the auxiliary lance at the blowing endpoint of historical furnaces, the slag test results of historical furnaces, and the corrected endpoint data, the data are classified according to the principle of similarity or similarity to establish a secondary database, and the calculated furnaces are categorized. S4, CFD simulation of slag density under different conditions: S401. Establish a geometric model: Establish a three-dimensional geometric model of the converter body and divide it into computational meshes; S402. Define the furnace environment as multiphase flow, which includes at least two phases: molten steel and slag. S403. Set physical property parameters: The chemical composition and temperature of the secondary database to which the calculation furnace belongs are transferred to the thermodynamic software through the CFD software. The thermodynamic software then returns physical property parameters, which are used to calculate the kinetic parameters for flow calculation, thereby calculating the steel-slag ratio of the steel flow in the axial direction. The dynamic parameters include molten steel flow velocity and cross-sectional area; The physical properties include slag density; S5. Infrared slag detection during steel tapping: S501. Acquiring image and temperature data: During the tapping process, the infrared thermal imager automatically tracks and captures images of the steel flow at the tapping spout, obtaining continuous image data and real-time temperature data of the molten steel. S502. Image data processing: Calculate the tapping port life and molten steel flow rate in the tapping port at different time periods during the tapping process of the heat. Based on different temperature thresholds, distinguish the far-infrared bands of the infrared radiation coefficients of molten steel and slag to obtain the steel-slag ratio in the radial direction of the steel flow. S503, Continuous calculation of slag discharge rate: Based on the axial slag ratio calculated in step S403 and the radial slag ratio calculated in step S502, the instantaneous slag ratio of the entire steel flow is calculated. Based on the instantaneous steel-slag ratio, tapping port life, molten steel flow velocity and slag density at different time points during the tapping process of a heat, the slag discharge amount for that heat is continuously calculated.

2. The method for calculating the amount of slag discharged during converter tapping according to claim 1, characterized in that, After the converter tapping is completed, the total slag discharge is obtained by summing up the results of continuous calculations.

3. The method for calculating the amount of slag discharged during converter tapping according to claim 1, characterized in that, The historical furnace charge information and calculated furnace charge information include the conditions of molten iron entering the furnace, the conditions of scrap steel, the conditions of slag-forming auxiliary materials, coolant, and slag-forming agent, the converter bottom blowing process parameters, the converter lining life, and the oxygen consumption of converter blowing.

4. The method for calculating the amount of slag discharged during converter tapping according to claim 3, characterized in that, The conditions for molten iron entering the furnace include the composition, temperature, weight, and amount of slag. The scrap steel conditions include the scrap steel structure type, weight, and scrap steel addition ratio; The conditions for the slag-forming auxiliary materials, coolants, and slag-reducing agents include their types, components, and amounts added.

5. The method for calculating the amount of slag discharged during converter tapping according to claim 1, characterized in that, The TSO test results of the secondary gun at the end of the blowing process include the end temperature, carbon content, and oxygen content.

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