Refining furnace production control method for receiving casting residues behind converter

Abstract

The invention discloses a refining furnace production control method for receiving casting residues behind a converter, which relates to the technical field of metallurgy and comprises LF molten steel arrival smelting process control and RH molten steel arrival treatment process control. According to the method, the three stages of preparation before pouring, LF molten steel station arriving smelting and RH station arriving coping are controlled, the air brick blocking probability is reduced, the molten steel component qualification rate is increased, and the requirement for on-site large-scale production is met.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a production control method for a refining furnace used for collecting cast residue after a converter furnace. Background Art

[0002] In the steel production process, recycling excess steel is a key step in improving resource utilization and reducing production costs. Excess steel refers to the molten steel and slag remaining in the ladle after the steel casting process is completed, which is then recycled. In traditional production processes, some of this excess steel is directly discarded, resulting in significant resource waste and increased costs. While some is recycled, its return to the refining process poses numerous challenges to refined steel quality and production stability.

[0003] The remaining molten steel has the following characteristics: 1. Large amount of slag; 2. Small clearance; 3. The remaining molten steel before tapping is easy to block the breathable bricks, resulting in poor argon gas.

[0004] The above characteristics may easily lead to the following problems: 1. Carbon increase problem; 2. Poor argon at the station; 3. Slag overflow during the heating process; 4. Abnormal aluminum degradation; 5. Desulfurization problem; 6. Foaming slag overflow and burning of RH equipment.

[0005] Therefore, it is extremely urgent to develop a refining furnace production control method for collecting cast waste after the furnace. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a refining furnace production control method for collecting cast residue after a converter furnace.

[0007] In order to solve the above technical problems, the technical solutions of the present invention are as follows: A production control method for a refining furnace for collecting cast-off after a converter, including LF molten steel arrival smelting process control and RH molten steel arrival processing process control; The LF molten steel arrival smelting process control includes: Turn on the argon gas and control the initial argon flow rate to 100NL / min. After the argon gas is blown out normally, control the argon flow rate to 50-80NL / min; During the deoxidation and slagging process, lime and aluminum wire are added to continuously remove oxygen from the slag; During the continuous heating stage, the bottom blowing argon flow rate is controlled to be 400-600NL / min and the pressure is 5.0-6.0Bar; After smelting, control the argon flow rate to 50-80NL / min and judge whether the slag is seriously foamed. If so, control the argon flow rate to 100-200NL / min. After removing the electrode, stir the molten steel with argon to make the temperature uniform and then measure the temperature. The RH molten steel arrival processing process control includes: The temperature of the molten steel arriving at the station is immediately measured and compared with the temperature of the refining ladle. If the difference between the two is greater than the threshold, the temperature of the molten steel is measured again. Measure the slag thickness and perform lifting operations according to the maximum range; Determine whether there is slag foaming, and immediately open the argon gas if it exists to promote the separation of steel slag, and add aluminum wire to the slag surface according to the aluminum content of LF outlet to maintain the stability of molten steel composition; The vacuum degree is tested to ensure that the vacuum degree during the RH treatment process meets the requirements.

[0008] As a preferred solution of the production control method for a refining furnace for collecting cast-off after a converter furnace according to the present invention, the LF molten steel arrival smelting process control further includes: After the argon difference occurs, the LF furnace is controlled to increase temperature and a bypass is used for pressurization.

[0009] As a preferred solution of the production control method for a refining furnace for collecting cast-off after a converter furnace according to the present invention, the LF molten steel arrival smelting process control further includes: Ensure that white slag is discharged when LF leaves the station, and when RH is producing normally, control the aluminum content and add it according to the upper limit of the regulation + 0.05%; when the aluminum entering the RH station is insufficient, add it according to the upper limit of the regulation + 0.05% before feeding the wire, and then judge whether the aluminum content is sufficient after feeding the wire, and if the aluminum content is still insufficient, add it according to the lower limit (+ 0.015 ~ 0.020)%.

[0010] As a preferred solution of the production control method of a refining furnace for collecting cast-off after a converter furnace according to the present invention, the LF molten steel arrival smelting process control further includes: performing a carbonization treatment.

[0011] As a preferred solution of the production control method of a refining furnace for collecting cast-off after a converter furnace according to the present invention, the method further comprises: controlling the pre-cast-off preparation stage before the LF molten steel arrival smelting process; The control of the pre-casting preparation stage includes: controlling the clearance of the ladle behind the converter to be greater than or equal to 400 mm when recovering the casting.

[0012] As a preferred embodiment of the refining furnace production control method for collecting cast residue after the converter according to the present invention, the control of the pre-cast residue preparation stage further includes: Control the time interval between the end of pouring before steel tapping and the start of steel tapping to be less than or equal to 10 minutes.

[0013] The beneficial effects of the present invention are: (1) The present invention controls the process through three stages: pre-casting preparation stage → LF molten steel arrival smelting stage → RH arrival response stage, thereby reducing the probability of blockage of air bricks and improving the qualified rate of molten steel composition, thus meeting the requirements of on-site large-scale production.

[0014] (2) The present invention reduces the occurrence of unfavorable production factors by controlling the pre-casting preparation stage; reduces the probability of composition incompatibility by controlling the LF molten steel arrival smelting stage and the RH arrival response stage; and reduces the frequency of process abnormalities and the generation of unplanned billets by promptly handling abnormal problems. DETAILED DESCRIPTION

[0015] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific implementation methods.

[0016] The present application provides a production control method for a refining furnace for collecting cast surplus after a converter furnace. The method adopts three stages of control: pre-cast surplus preparation stage → LF molten steel arrival smelting stage → RH arrival response stage. The method is specifically implemented through the following technical solutions: (1) Control during the preparation phase before pouring: 1.1. Information Communication and Product Control: After taking over their shift, refining furnace operators must promptly notify the dispatcher and foreman. They must clearly prohibit overcasting of key steel grades to prevent uncontrolled impacts on the quality of these special steel grades. Furthermore, detailed information on overcast steel grades must be recorded to facilitate targeted follow-up operations.

[0017] 1.2. Ladle Clearance and Overfill Management: Strictly enforce ladle clearance requirements. When recovering overfill, ensure the ladle clearance behind the converter is ≥400mm (one layer of vertical bricks and two layers of horizontal bricks). Ladle clearance after overfill must also be one layer of vertical bricks. Overfill is strictly prohibited in ladles that do not meet clearance requirements. If the clearance is insufficient, slag removal should be performed in advance. Furthermore, overfill is prohibited in connecting heats, and molten steel from the same ladle can only be overfilled in a single ladle to avoid complications that could affect refining results. The interval between the end of overfill before tapping and the start of tapping must not exceed 10 minutes.

[0018] 1.3. Special Ladle and Argon Management: For abnormal ladles, such as those undergoing major or medium repairs, brand new ladles, or ladles with bottoms, it is prohibited to pour excess steel before tapping. Argon must be turned on in the converter before tapping and pouring excess steel, and the argon gas must be kept on after pouring excess steel to maintain the flow of molten steel and prevent blockage of air bricks.

[0019] 1.4. Coordination of converter tapping parameters: Actively communicate with the converter to increase the tapping temperature and carbon content of the tapping steel, thereby reducing the subsequent heating and carbon addition tasks of the refining furnace and creating favorable conditions for the stable operation of the refining furnace.

[0020] 1.5. Equipment Inspection and Maintenance: Upon taking over a shift, check the furnace door and wire feed hole for slag blockage. If so, notify relevant personnel to clear it immediately to prevent jamming during carbon powder addition, which could affect carbon powder yield. Also, notify professionals to calibrate the temperature gun, check the argon gas line to ensure there are no leaks, and confirm the normal operation of other equipment, including the wire feeder. Additionally, purge the ladle bottom air bricks strictly according to standardized purge flow rates to ensure unobstructed flow.

[0021] (2) LF molten steel arrival smelting process control: 2.1. Confirmation of Residual Information and Determination of Slag Quantity: Upon arrival of molten steel, operators immediately confirm the specific details of the residual heat with the dispatcher, foreman, and converter, including whether the residual is before or after tapping, whether it is repeated, and the type of residual steel. Based on the difference in slag volume between vacuum steel and ordinary steel, the total slag volume of the residual steel can be quickly and accurately determined, providing a basis for subsequent operations.

[0022] 2.2 Argon Control: Turn on the argon gas promptly, with the initial flow rate set at 100, 100 NL / min. If the argon gas does not blow out normally within one minute, immediately use the bypass to blow open the blocked air brick. After the argon gas is normal, maintain the flow rate at 50-80 NL / min to ensure that the molten steel is not exposed and maintain good stirring effect.

[0023] 2.3 Power Supply and Deoxidation and Slagging Operations: Strictly follow standardized power supply regulations to ensure stable energy input within the refining furnace. Regarding deoxidation and slagging, given the high volume and slagging characteristics of castable slag, lime and aluminum wire are added according to the slag consistency to continuously remove oxygen from the slag. Frequently take slag samples to observe deoxidation. Depending on the castable steel grade, reduce the amount of lime in the slagging material by 100-200 kg. Closely monitor the effectiveness of bottom blowing and desulfurization, and promptly report any abnormalities to the command center.

[0024] 2.4 Bottom-blowing Argon and Slag Overflow Prevention: During continuous temperature increase, the bottom-blowing argon flow rate must be kept constant, preferably 400-600 NL / min and a pressure of 5.0-6.0 Bar. This prevents slag foaming and severe slag overflow, which could damage the argon pipe and equipment. When adding lime during the process, power should be turned off. If severe slag overflow occurs, add fluorite or discontinue the lower electrode.

[0025] 2.5. Carbon addition operation: LF carbon addition is mainly for alloy carbon addition, such as high carbon ferromanganese and high carbon ferrochrome. When using carbon powder for carbon addition, first lift the electrode, increase the argon gas and perform bypass stirring. After alloying, ensure that the alloy and carbon powder have more than 3 minutes of melting time. It is strictly forbidden to take samples immediately after adding carbon powder. When adding carbon powder, lift the electrode and stir for 1-2 minutes. When the argon gas is very poor, a small amount of calcium wire can be fed for stirring. It is strictly forbidden to add carbon powder when lowering the electrode to avoid carbon powder burning and affecting the yield. Carbon powder is not added to the slag surface after the LF leaves the station. It can be added during RH wire feeding.

[0026] 2.6. Treatment of argon abnormality: When argon gas deficiency occurs, that is, argon gas flows out from one side of the cladding wall or even there is no stirring effect in the furnace, first quickly increase the temperature, use bypass pressure, feed calcium wire for stirring when necessary, and report to the foreman and dispatcher in time, apply for speed reduction treatment, and inform relevant personnel of the hazards. If time permits, rush to make molten steel in the next furnace.

[0027] 2.7. End of smelting operation: After smelting is completed, it is strictly forbidden to turn off the argon gas immediately. First, adjust the argon gas flow to 50-80NL / min. If the slag foams severely, adjust the argon gas flow to 100-200NL / min to promote slag-steel separation and prevent slag foaming at RH that affects the processing time. Do not measure the temperature immediately after removing the electrode. First, use argon gas to stir the molten steel to make the temperature uniform, and then measure the temperature. If the temperature deviates significantly from the predicted temperature, re-measure the temperature to confirm.

[0028] 2.8. Aluminum Content Control: Ensure white slag exits the LF station. When the RH trough is operating normally, aluminum content is added according to the specified upper limit + 0.05%. If the RH inlet aluminum content is insufficient, add the specified upper limit + 0.05% before feeding the wire. If the aluminum content is still insufficient after feeding the wire, add the lower limit (+ 0.015 ~ 0.020)% and keep records.

[0029] (3) RH molten steel arrival processing process control: 3.1 Temperature Comparison and Confirmation: Upon arrival of the molten steel, the temperature is measured immediately and compared with the refining ladle temperature. If the deviation is large (±5°C), the temperature is measured again to ensure that the temperature data is accurate and reliable, providing a correct basis for subsequent operations.

[0030] 3.2 Slag thickness measurement and jacking operation: Accurately measure the slag thickness and perform jacking operation according to the maximum range to ensure that the jacking is completed without sucking slag or burning the lifting gas pipe. If necessary, perform supplementary jacking to ensure the smooth progress of the RH treatment process.

[0031] 3.3 Slag foaming treatment: If slag foaming is found upon arrival at the station, immediately open the argon gas to promote the separation of slag and steel, and add aluminum wire to the slag surface according to the aluminum content of LF outgoing station to maintain the stability of the molten steel composition.

[0032] 3.4 Vacuum degree monitoring: When pumping vacuum, pay close attention to the changes in vacuum degree to ensure that RH treatment is carried out in a suitable vacuum environment to ensure the quality of molten steel.

[0033] The above solution will be further described below through specific embodiments.

[0034] For example, a heat at one plant begins pouring the excess steel before tapping after the converter, with a 6-minute delay until tapping begins. Argon is immediately turned on upon arrival at the LF station, and bypass pressure is applied, which is promptly reduced after the argon is introduced. During the process, the bottom-blown argon is opened at a rate of 600 / 600 nl / min. High-carbon ferromanganese is used for carburization, and the aluminum content of the hanging ladle is controlled to the regulatory upper limit +0.05%. Upon arrival at the RH station, temperature comparisons are performed, slag thickness is measured, and lifting is performed to the maximum stroke. Vacuuming is then initiated to observe foaming of the molten steel. The vacuum level and tumbling effect within the vacuum tank are also observed. These measures ensure that the finished product composition and temperature meet all requirements, and subsequent plate flaw detection also passes.

[0035] Therefore, the technical solution of the present application is controlled through three stages: pre-pouring preparation stage → LF molten steel arrival smelting stage → RH arrival response stage, which reduces the probability of blockage of breathable bricks and improves the qualified rate of molten steel composition, meeting the requirements of on-site large-scale production.

[0036] In addition to the above embodiments, the present invention may also have other implementation methods; any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A production control method for a refining furnace for collecting cast-off after a converter furnace, characterized in that: Including LF molten steel arrival smelting process control and RH molten steel arrival treatment process control; The LF molten steel arrival smelting process control includes: Turn on the argon gas and control the initial argon flow rate to 100NL / min. After the argon gas is blown out normally, control the argon flow rate to 50-80NL / min. During the deoxidation and slagging process, lime and aluminum wire are added to continuously remove oxygen from the slag; During the continuous heating stage, the bottom blowing argon flow rate is controlled to be 400-600NL / min and the pressure is 5.0-6.0Bar; After smelting, control the argon flow rate to 50-80NL / min and judge whether the slag is seriously foamed. If so, control the argon flow rate to 100-200NL / min. After removing the electrode, stir the molten steel with argon to make the temperature uniform and then measure the temperature. The RH molten steel arrival processing process control includes: The temperature of the molten steel arriving at the station is immediately measured and compared with the temperature of the refining ladle. If the difference between the two is greater than the threshold, the temperature of the molten steel is measured again. Measure the slag thickness and perform lifting operations according to the maximum range; Determine whether there is slag foaming, and immediately open the argon gas if it exists to promote the separation of steel slag, and add aluminum wire to the slag surface according to the aluminum content of LF outlet to maintain the stability of molten steel composition; The vacuum degree is tested to ensure that the vacuum degree during the RH treatment process meets the requirements.

2. The production control method for a refining furnace for collecting cast-off after a converter according to claim 1, characterized in that: The LF molten steel arrival smelting process control also includes: After the argon difference occurs, the LF furnace is controlled to increase temperature and a bypass is used for pressurization.

3. The production control method for a refining furnace for collecting cast-off after a converter according to claim 1, characterized in that: The LF molten steel arrival smelting process control also includes: Ensure that white slag is discharged when LF leaves the station, and when RH is producing normally, control the aluminum content and add it according to the upper limit of the regulation + 0.05%; when the aluminum entering the RH station is insufficient, add it according to the upper limit of the regulation + 0.05% before feeding the wire, and then judge whether the aluminum content is sufficient after feeding the wire, and if the aluminum content is still insufficient, add it according to the lower limit (+ 0.015 ~ 0.020)%.

4. The production control method for a refining furnace for collecting cast-off after a converter according to claim 1, characterized in that: The LF molten steel arrival smelting process control also includes: performing carbon addition treatment.

5. The production control method for a refining furnace for collecting cast-off after a converter according to claim 1, characterized in that: Before the LF molten steel arrival smelting process control, it also includes: pre-casting preparation stage control; The control of the pre-casting preparation stage includes: controlling the clearance of the ladle behind the converter to be greater than or equal to 400 mm when recovering the casting.

6. The production control method for a refining furnace for collecting cast-off after a converter according to claim 5, characterized in that: The control of the pre-casting preparation stage also includes: Control the time interval between the end of pouring before steel tapping and the start of steel tapping to be less than or equal to 10 minutes.