A production method and system for precisely controlling steel alloy components of a converter straight-up

Abstract

The application provides a production method and system for precise control of converter straight-up steel alloy components, and belongs to the technical field of steel metallurgy. The method steps include: during the converter tapping process, a predetermined amount of pre-deoxidizer is automatically added to the ladle, and the addition time of the pre-deoxidizer is earlier than the addition time of the alloy; based on the charging capacity of the converter, the tapping capacity, and the grade and preset recovery rate of each alloy element, the required alloy type and weight are automatically calculated, and automatic weighing and addition are performed; after each alloy weighing is completed, the increment of each alloy element in the molten steel is calculated and displayed in real time, and the calculation result is compared with the preset target component range; if the calculated value of a certain element is lower than the preset lower limit value, an alarm signal is issued. The method provided by the application can effectively stabilize the alloy recovery rate, realize precise control of the alloy components, and reduce the risk of human error and labor intensity.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a production method and system for precise control of alloy composition in direct converter steel. Background Technology

[0002] Converter steelmaking is one of the main processes in modern steel production. During the converter tapping process, deoxidation and alloying operations are required, which involves adding deoxidizers and various ferroalloys to the molten steel in the ladle to adjust the chemical composition of the steel to meet the specifications of the target steel grade. The precision of alloy composition control directly affects the quality, performance, and production cost of the steel.

[0003] In traditional converter steelmaking processes, especially in low iron-to-steel ratio conditions, over-oxidation frequently occurs during converter smelting, leading to excessively high and volatile dissolved oxygen content in the molten steel. This results in highly unstable recovery rates for subsequently added alloys (such as ferrosilicon and high-carbon ferromanganese), with a lack of reference between heats, posing significant challenges to alloy blending. To reduce alloy costs, steel mills often employ a composite blending approach, using ferrosilicon balls, high-carbon ferromanganese, and ferrosilicon alloys to achieve narrow compositional coverage of various elements. However, this complex blending method places extremely high demands on the furnace operator's experience and skills. The furnace operator must perform tedious and complex calculations for each heat to determine the optimal addition amounts of various alloys.

[0004] This highly manual operation method has many drawbacks: 1. Unstable alloy recovery rate: Due to the varying degrees of over-oxidation in molten steel, the alloy recovery rate fluctuates greatly, often resulting in key elements such as Si and Mn failing to enter the target composition range of the smelted steel, causing the molten steel to be re-judged or even scrapped, which seriously affects product quality and yield.

[0005] 2. High risk of human error: There are many types of alloys and the calculations are complex. Personnel in the workplace are prone to negligence during long hours of high-intensity work, which may lead to omissions, misweighing, or overweighing of alloys, and may also cause quality accidents such as unqualified steel composition.

[0006] 3. High labor intensity: Furnace operators need to bear enormous mental pressure and heavy calculation tasks, which is not conducive to improving production efficiency and employee health.

[0007] 4. It is not conducive to cost control: In order to ensure that the composition is qualified, operators often tend to add more alloy, resulting in alloy waste and increasing production costs.

[0008] Therefore, there is an urgent need for a converter direct-load steel alloy production method that can effectively stabilize alloy recovery rate, achieve precise control of alloy composition, and reduce the risk of human error and labor intensity. Summary of the Invention

[0009] The purpose of this invention is to provide a production method and system for precise control of alloy composition in converter direct-cook steel, aiming to solve the following key technical problems: 1. Improve the relative stability of alloy recovery rate and eliminate large fluctuations in recovery rate caused by steel over-oxidation.

[0010] 2. To achieve economical and efficient utilization of multiple alloy varieties and reduce alloy costs.

[0011] 3. Achieve precise and automated control of multiple elements such as C, Si, Mn, and N in molten steel, avoiding composition deviations caused by human factors.

[0012] 4. Reduce the labor intensity of operators and improve production efficiency and product quality stability.

[0013] To address the aforementioned technical problems, this invention provides a production method for precise control of alloy composition in converter direct-fired steel. This method mainly includes two core technical modules: an automatic pre-deoxidation module and an automatic alloy calculation and monitoring module.

[0014] This invention provides a production method for precise control of alloy composition in converter steel produced via direct feed, comprising the following steps: S1. Automatic pre-deoxidation step: During the steel tapping process of the converter, a predetermined amount of pre-deoxidizer is automatically added to the ladle. The pre-deoxidizer is added earlier than the alloy is added.

[0015] S2. Automatic alloy calculation and addition steps: Based on the converter's charging amount, steel output, and the grade and preset recovery rate of each alloy element, the required alloy type and weight are automatically calculated, and automatic weighing and addition are performed.

[0016] S3. Real-time monitoring and alarm procedure for alloy composition: After each alloy weighing is completed, the increment of each alloy element in the molten steel is calculated and displayed in real time, and the calculation result is compared with the preset target composition range. If the calculated value of a certain element is lower than the preset lower limit, an alarm signal is issued.

[0017] Preferably, in step S1, the pre-deoxidizer is carbon powder. As a pre-deoxidizer, carbon powder's deoxidation product is CO gas, which can directly escape from the molten steel without producing solid or liquid inclusions, thus improving the purity of the molten steel. The amount of carbon powder added is 20-40 kg, with a maximum of 30 kg. The pre-deoxidizer is added 10-20 seconds before the automatic alloy addition time, with a maximum of 15 seconds. This time window ensures that the carbon powder has sufficient time to react with oxygen in the molten steel, reducing its oxidizing properties, while preventing excessive carbon loss or affecting subsequent alloying effects due to premature addition.

[0018] Preferably, in step S1, the automatic pre-deoxygenation step is completed by a separate automatic pre-deoxygenation system. This system includes: A pre-deoxidation silo located at an elevated position is used to store pre-deoxidizing agents, such as toner.

[0019] A weighing device connected to the pre-deoxidation chamber, such as a high-precision electric vibratory feeder and receiving hopper, is used to weigh the pre-deoxidizer to ensure that the weighing accuracy is controlled within 3‰.

[0020] A conveying pipe, such as a rigid steel pipe, connecting the weighing device and the alloy feeding system is used to directly feed the weighed pre-deoxidizer into the alloy feeding chute, sharing the feeding channel with the alloy, without the need for an additional feeding chute.

[0021] Preferably, in step S2, the automatic calculation is based on an automatic alloy calculation model. This model automatically collects the amount of molten iron and scrap steel charged for each heat of steel from the secondary machine (process control computer) in the plant, and pre-calculates the amount of molten steel to be tapped according to a preset steel tapping formula (e.g., steel tapping = total charge - slag - splash loss). Subsequently, a dedicated alloy system acquisition module is designed for the charging sequence of the alloy hoppers of each converter, and sets calculation formulas for different grades (percentage of element content) and preset recovery rates of various alloys such as ferrosilicon, high-carbon ferromanganese, and ferrosilicon spheres, thereby accurately calculating the theoretical amount of each alloy to achieve the target composition.

[0022] Preferably, in step S2, the automatic weighing and addition are achieved through a dedicated alloy system acquisition module that corresponds one-to-one with the alloy silo. This module receives instructions from the automatic alloy calculation model, controls the start and stop of weighing devices such as vibrating feeders or belt scales, and accurately weighs the required weight of alloy. After weighing is completed, the weighing data is fed back to the control system in real time.

[0023] Preferably, in step S3, the real-time monitoring and alarm step further includes: setting up a platform scale on the ladle car to measure the actual weight of the molten steel before and after tapping. The furnace manager can compare the difference in molten steel weight displayed on the platform scale before and after tapping (i.e., the actual tapped amount) with the theoretically calculated tapped amount. If the deviation is large (for example, due to abnormal conditions such as opening the furnace opening or sucking pig iron, the actual tapped amount is much smaller than the theoretical value), the furnace manager can quickly issue an instruction to add alloys and complete the composition fine-tuning operation at the argon station in advance, effectively avoiding the recalculation of molten steel due to low Mn and Si elements.

[0024] Preferably, in step S1, the trigger signal for the automatic pre-deoxidation step can be one or more of the following signals: "heat start", "tap start", or "automatic alloy addition". For example, it can be set such that: the "heat start" signal triggers the automatic weighing of the pre-deoxidizer; the "tap start" signal, in conjunction with the "automatic alloy addition" signal, triggers the automatic addition of the pre-deoxidizer, and it is set to be added preferentially 15 seconds before the alloy is added.

[0025] The present invention also provides a precise control system for alloy composition of converter direct-cook steel for implementing the above method, comprising: The pre-deoxidation unit is used to automatically add a predetermined amount of pre-deoxidizer into the ladle before the alloy is added; The automatic alloy calculation and weighing unit is used to automatically calculate the required amount of alloy based on process parameters and control the weighing. The alloy composition monitoring and alarm unit is used to calculate the increase of alloy elements in real time and compare it with a preset threshold, and issue an alarm when it exceeds the range. In addition, a central controller is used to coordinate and control the operation of the above-mentioned units.

[0026] Preferably, the pre-deoxygenation unit includes: A pre-deoxidizer storage bin; A weighing device connected to the storage bin, with a weighing accuracy of less than 3‰; A receiving hopper with double limit gate valves located below the weighing device. When the gate valves are closed, the receiving hopper is completely sealed to ensure no leakage. A rigid steel pipe connecting the receiving hopper and the alloy unloading rotating mechanism.

[0027] Preferably, the alloy composition monitoring and alarm unit is also equipped with a display interface (such as an HMI human-machine interface) to display the current calculated values ​​of each element such as C, Si, Mn, and N and their deviations from the target values ​​in real time, so that operators (furnace managers, lance operators) can clearly check the alloy addition status at a glance.

[0028] The present invention provides a production method and system for precise control of alloy composition in converter direct-cook steel, which has the following significant advantages: 1. Significantly improves the stability and average value of alloy recovery rate: By automatically and quantitatively adding carbon powder for pre-deoxidation before alloy addition, the oxygen content in the molten steel is effectively reduced, eliminating large fluctuations in alloy recovery rate caused by different degrees of steel over-oxidation. Experimental data shows that after adopting the pre-deoxidation method of this invention, the average manganese recovery rate increased by 1.85% (from 91.06% to 92.91%), and there were no more heats with manganese recovery rates below 88%, greatly improving the stability of alloy recovery rate.

[0029] 2. Achieve precise control of alloy composition and eliminate quality accidents: Through an automatic alloy calculation model and a real-time monitoring and alarm system, the entire process from alloy calculation to weighing and addition is automated and intelligent. The system automatically calculates the theoretical addition amount and displays the increase of each element in real time after weighing. If any element (such as Mn or N) is found to be below the preset lower limit, an alarm pops up immediately to remind the personnel to confirm. This fundamentally solves the problem of unqualified steel composition caused by human calculation errors, omissions, or over-weighing, and achieves high-precision targeting of C, Si, Mn, and N elements in steel grades such as rebar. Practical data shows that after adopting this method, the proportion of heats with Mn content within the target range in the tundish reaches as high as 99.26%, and the number of heats that need to be reclassified due to inconsistencies in C, Si, and Mn composition is reduced to zero.

[0030] 3. Reduce alloy costs and achieve economical alloy usage: A stable alloy recovery rate allows the furnace operator to more accurately predict the amount of alloy added, avoiding waste caused by blindly adding excessive amounts of alloy to ensure qualified composition. Furthermore, this method supports the combined use of multiple alloys (such as ferrosilicon balls, high-carbon ferromanganese, etc.), enabling flexible utilization of lower-priced alloy varieties and minimizing alloy procurement costs without compromising quality.

[0031] 4. Reduce labor intensity and improve production efficiency: Freeing furnace operators from tedious and stressful manual calculations significantly reduces their mental and physical burden. Automated operation processes minimize human intervention, shorten alloy addition time, and improve production pace. Simultaneously, the application of ladle car scales allows furnace operators to quickly and accurately determine whether additional alloy is needed, completing argon station composition adjustments ahead of schedule, further enhancing production efficiency and product quality.

[0032] 5. Improve steel quality: Carbon powder is used as a pre-deoxidizer. Its deoxidation product is gaseous CO, which escapes directly from the molten steel. Unlike the deoxidation products of elements such as Si and Mn (SiO2, MnO), it does not remain in the molten steel and form non-metallic inclusions, thereby improving the purity and internal quality of the molten steel. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the automatic pre-deoxygenation system in Embodiment 1 of the present invention; Explanation of reference numerals in the attached drawings: 1-Pre-deoxidation bin, 2-Electric vibratory feeder, 3-Receiving hopper, 4-Weighing sensor, 5-Hard steel pipe, 6-Rotating mechanism, 7-Alloy discharge chute, 8-Steel ladle. Detailed Implementation

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0035] Example 1 This embodiment provides a production method for precise control of alloy composition in converter direct-flow steel, which is applied to a 120-ton top and bottom blowing converter production line in a steel plant, mainly producing HRB400 series rebar.

[0036] 1. Implementation of the automatic pre-deoxygenation module like Figure 1 As shown, in this embodiment, a dedicated pre-deoxidation bin 1 is first added to the high-level material bin area of ​​the converter to store carbon powder with uniform particle size. This pre-deoxidation bin shares a feeding belt system with the original alloy system, eliminating the need for additional investment in feeding equipment.

[0037] Below the pre-deoxidation chamber 1, an independent high-precision weighing system is installed, including an electric vibratory feeder 2 and a receiving hopper 3. The vibration frequency of the electric vibratory feeder 2 is controllable, enabling precise delivery of carbon powder from the pre-deoxidation chamber 1 to the receiving hopper 3. The receiving hopper 3 is mounted on a weighing sensor 4, with weighing accuracy controlled within 3‰. The bottom outlet of the receiving hopper 3 is equipped with a double-limit gate valve. When the gate valve is closed, the lower part of the receiving hopper 3 is completely sealed, completely eliminating material leakage.

[0038] Below the slide gate valve, a rigid steel pipe 5 connects directly to the rotating mechanism 6 of the alloy feeding system, and ultimately to the alloy feeding chute 7. In this way, the pre-deoxidizer (carbon powder) can be added to the ladle 8 before the alloy is added, via this path.

[0039] An automatic weighing and addition control program for the pre-deoxidizer was developed in the control system. This program supports both "automatic" and "manual" modes.

[0040] In "Automatic" mode, the program is configured with the following logic: Trigger signal: The "furnace start" signal is used as the trigger signal for automatic carbon powder weighing. When the converter starts a new furnace cycle, the system automatically starts the electric vibratory feeder 2 and adds carbon powder to the receiving hopper 3 according to the set weight (30kg in this embodiment).

[0041] Timing of Carbon Powder Addition: The automatic addition of carbon powder is triggered by both the "Steel Tapping Start" signal and the "Automatic Alloy Addition" signal. When the converter tapps steel and the system is ready to start the automatic alloy addition process, the program will first open the gate valve of the pre-deoxidation system, adding 30kg of pre-weighed carbon powder into the ladle 8 through pipe 5 and chute 7. The carbon powder addition time is set to 15 seconds before the automatic addition time of the first batch of alloy.

[0042] Safety Interlocks: The program is equipped with multiple safety interlocks. For example, the upper limit for toner is set to 40kg to prevent over-addition due to accidental operation; if the weight displayed in receiving hopper 3 is greater than 10kg, a new round of automatic weighing will not be performed to prevent duplicate weighing; if the pre-deoxidation discharge valve (slide valve) malfunctions, the system will pop up an alarm window to prompt the operator to handle the situation.

[0043] In "Manual" mode, operators can manually set the weighing weight through the HMI interface and manually control the weighing and adding process to deal with equipment maintenance or special working conditions.

[0044] 2. Implementation of the Alloy Automatic Calculation and Monitoring Module This embodiment provides an automatic alloy calculation model, which is integrated into the converter's process control system.

[0045] Data Acquisition: The system automatically collects the amount of molten iron and scrap steel charged for each heat of steel from the secondary machine, and calculates the theoretical amount of molten steel according to the preset formula: Steel Output = Total Charged Amount × 0.9 (the coefficient is calibrated according to the actual situation of the plant).

[0046] Alloy Calculation: A dedicated data acquisition module was designed for the plant's three alloy silos (containing silicon-manganese alloy, high-carbon ferromanganese, and nitrogen enhancer, respectively). Operators need to pre-input the elemental grades of each alloy (e.g., silicon-manganese alloy containing 65% Mn and 18% Si) and preset recovery rates (e.g., Mn recovery rate 92%, Si recovery rate 85%) on the HMI. After the furnace manager inputs the target steel grade (e.g., HRB400E) and target composition range (e.g., Mn: 1.32%-1.45%, Si: 0.45%-0.60%) on the HMI, the system automatically calculates the theoretical weight of alloy required for each silo.

[0047] Weighing and Feedback: After calculation, the system sends instructions to the PLC controller of each alloy hopper, driving the electric vibratory feeder for automatic weighing. On the alloy screen, the system displays the "set value" and "actual weighing value" of each hopper in real time.

[0048] Composition Monitoring and Alarm: After each alloy weighing, the system immediately calculates the expected increase in C, Si, Mn, and N elements in the molten steel after the addition, based on the actual weighing value, alloy grade, and recovery rate. This information is then displayed cumulatively in the "Element Content" module in the upper right corner of the screen. Simultaneously, the system sets theoretical lower limits for the rebar series produced by this plant (e.g., Mn ≥ 1.28%, N ≥ 0.012%). If the calculated Mn or N element content is lower than this lower limit, the system immediately displays a prominent red alarm box accompanied by an audible alert, reminding personnel that "Element XX is too low; please confirm whether the alloy weighing is complete." Upon seeing the alarm, the furnace manager or lance operator can quickly verify the on-site weighing situation and promptly correct any possible omissions or errors.

[0049] 3. Application of ladle car platform scales In this embodiment, a high-precision platform scale is installed on the ladle car. Before tapping, the system records the weight of the empty ladle car; after tapping, the total weight of the ladle car, containing molten steel and slag, is recorded again. The system automatically calculates the actual tapped steel volume (total weight - empty ladle weight). The furnace operator can view this actual tapped steel volume in real time in the control room.

[0050] If the actual steel output deviates significantly from the theoretical output (for example, due to furnace opening repairs or pig iron removal, the actual steel output is 2 tons less than the theoretical value), the furnace manager can immediately determine that the current alloy addition may be insufficient to achieve the required steel composition. In this case, he can quickly input the required amount of alloy to be added into the HMI, and the system will restart the weighing and addition process to add the missing alloy to the ladle. This operation can be completed before argon processing, greatly improving the efficiency and accuracy of composition adjustment.

[0051] Experimental effect verification To verify the effectiveness of the invention, the factory conducted a comparative experiment. The test results are shown in Table 1 below.

[0052] Table 1

[0053] As can be seen from Table 1, after adopting the pre-deoxidation method of the present invention, the average manganese recovery rate increased by 1.85%, and the manganese recovery rate of all furnaces was higher than 88%, completely eliminating furnaces with low recovery rates, which proves the significant effect of the method in stabilizing and improving the alloy recovery rate.

[0054] In addition, our plant produced 1220 heats of square billet rebar (HRB400-B2) in February, all of which used the technical solution of this invention for heats with intermediate ladle composition analysis. Statistical results show that the average Mn content in the intermediate ladle was 1.283% (plant internal control requirement ≤1.40%, target 1.32%-1.45%), with 1211 heats meeting the Mn content target range of 1.32%-1.45%, accounting for a high proportion of 99.26%. There were zero heats reclassified due to inconsistencies in C, Si, and Mn composition that month. This indicates that the automatic alloy calculation and monitoring system of this invention has successfully achieved precise control of alloy composition, greatly improving the stability of product quality.

[0055] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A production method for precisely controlling the alloy composition of steel produced directly from a converter, characterized in that, Includes the following steps: S1. Automatic pre-deoxidation step: During the steel tapping process of the converter, a predetermined amount of pre-deoxidizer is automatically added to the ladle. The pre-deoxidizer is added earlier than the alloy is added. S2. Automatic alloy calculation and addition steps: Based on the converter's charging amount, tapping amount, and the grade and preset recovery rate of each alloy element, the required alloy type and weight are automatically calculated, and automatic weighing and addition are performed. S3. Real-time monitoring and alarm procedure for alloy composition: After each alloy weighing is completed, the increment of each alloy element in the molten steel is calculated and displayed in real time, and the calculation result is compared with the preset target composition range. If the calculated value of a certain element is lower than the preset lower limit, an alarm signal is issued.

2. The production method for precise control of alloy composition in converter direct-fired steel according to claim 1, characterized in that, In step S1, the pre-deoxidizer is carbon powder, and the amount added is 20-40 kg; the addition time of the pre-deoxidizer is 10-20 seconds earlier than the automatic addition time of the alloy.

3. The production method for precise control of alloy composition in converter direct-fired steel according to claim 1 or 2, characterized in that, In step S1, the automatic pre-deoxygenation step is completed by an independent automatic pre-deoxygenation system, which includes: A pre-deoxidation chamber located in an elevated silo; A weighing device connected to the pre-deoxidation chamber for weighing the pre-deoxidizing agent; A conveying pipe connecting the weighing device and the alloy feeding system is used to send the weighed pre-deoxidizer into the alloy feeding chute.

4. The production method for precise control of alloy composition in converter direct-fired steel according to claim 1, characterized in that, In step S2, the automatic calculation is based on an automatic alloy calculation model. This model automatically collects the amount of steel charged in each furnace from the secondary machine, calculates the amount of molten steel according to the preset steel output calculation formula, and then calculates the theoretical amount of each alloy by combining the grade and recovery rate of each alloy element.

5. The production method for precise control of alloy composition in converter direct-cook steel according to claim 1 or 4, characterized in that, In step S2, the automatic weighing and addition are achieved through a dedicated alloy system acquisition module that corresponds one-to-one with the alloy silo. This module controls the start and stop of the weighing device and feeds back the weighing data to the control system in real time.

6. The production method for precise control of alloy composition in converter direct-fired steel according to claim 1, characterized in that, In step S3, the real-time monitoring and alarm step further includes: setting up a platform scale on the ladle car to measure the actual weight of the molten steel before and after tapping; the furnace manager determines whether alloy needs to be added based on the difference between the actual weight and the theoretically calculated weight of the molten steel.

7. The production method for precise control of alloy composition in converter direct-fired steel according to claim 1, characterized in that, In step S1, the trigger signal for the automatic pre-deoxidation step is selected from one or more of the signals of "start of furnace", "start of tapping", or "automatic addition of alloy".

8. A precise control system for alloy composition of converter direct-cook steel used to implement the method of any one of claims 1-7, characterized in that, include: The pre-deoxidation unit is used to automatically add a predetermined amount of pre-deoxidizer into the ladle before the alloy is added; The automatic alloy calculation and weighing unit is used to automatically calculate the required amount of alloy based on process parameters and control the weighing. The alloy composition monitoring and alarm unit is used to calculate the increase of alloy elements in real time and compare it with a preset threshold, and issue an alarm when it exceeds the range. In addition, a central controller is used to coordinate and control the operation of the above-mentioned units.

9. The system according to claim 8, characterized in that, The pre-deoxygenation unit includes: A pre-deoxidizer storage bin; A weighing device connected to the storage bin, with a weighing accuracy of less than 3‰; A receiving hopper with double limit gate valves located below the weighing device is used to prevent leakage; A rigid steel pipe connecting the receiving hopper and the alloy unloading rotating mechanism.

10. The system according to claim 8 or 9, characterized in that, The alloy composition monitoring and alarm unit is also equipped with a display interface for real-time display of the current calculated values ​​of each element such as C, Si, Mn, and N, as well as their deviations from the target values.

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