A converter smelting control method for a chromium microalloyed HRB500E series steel

Abstract

The application provides a converter smelting control method for HRB500E steel grade. In the case that the total amount of scrap steel is unchanged, the content of chromium elements entering the converter is increased by changing the ratio of loading structure types, that is, the reasonable matching of different types of scrap steel, and the converter smelting control process is optimized, the slagging system, the oxygen supply system and the end point system are adjusted, the early slagging of the initial slag, the process slagging of the slag and the sticky final slag are realized, and the content of chromium elements in the initial molten steel can be significantly improved. The application can greatly improve the residual chromium ratio of the initial molten steel, and then reduce the addition amount of chromium alloy, and the alloy cost is significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, and relates to a converter smelting control method for HRB500E steel, and more particularly to a converter smelting control method for chromium-containing microalloyed HRB500E series steel. Background Technology

[0002] The HRB500E series steel grades are the threaded steel bar grades specified in GB_T 1499.2-2018 "Steel for Reinforced Concrete". Due to the wide range of standard composition and the differences in production organization mode and process control among various manufacturers, the composition of HRB500E hot-rolled ribbed steel bars produced by different steel mills also varies.

[0003] To ensure mechanical strength and performance meet standards, most domestic enterprises use vanadium-nitrogen alloys for vanadium microalloying or niobium-iron alloys for niobium microalloying. However, the high cost of vanadium and niobium alloys leads to high production costs. Performance enhancement can be achieved by introducing other elements. Adding chromium can increase the solubility of vanadium in austenite, lowering the temperature at which vanadium precipitates to its maximum extent, increasing the solid solution strengthening effect of vanadium, and mitigating the effects of precipitation strengthening and grain refinement. This avoids excessive grain refinement in the steel, significantly improving both yield strength and tensile strength. This approach allows for the reduction of the amount of expensive alloys such as vanadium and niobium while still meeting the performance requirements of the steel.

[0004] With the rapid development of the iron and steel metallurgy industry, domestic scrap steel resources are gradually increasing, and the types of scrap steel available for converter smelting are also increasing. Examples include heavy briquettes, rebar briquettes, mixed material briquettes, steel chip briquettes, and shavings briquettes. Among these, steel chip briquettes are cylindrical briquettes made from mechanically processed steel chips; shavings briquettes are briquettes made from shavings and wire scrap produced by milling machines and CNC machine tools, and are free of oil, impurities, and rust.

[0005] Therefore, how to maximize the energy efficiency of scrap steel resources while simultaneously reducing costs and increasing efficiency in the production of HRB500E series steel grades is one of the urgent problems that steel companies need to solve. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a converter smelting control method for HRB500E steel, particularly a converter smelting control method for chromium-containing microalloyed HRB500E series steel. In the production of chromium-containing microalloyed HRB500E series steel, the present invention optimizes the scrap steel type and proportioning in the furnace. By optimizing the converter smelting control process, the residual chromium ratio in the initial smelting of molten steel can be significantly increased, thereby reducing the amount of chromium alloys added, resulting in a significant reduction in alloy costs.

[0007] This invention provides a converter smelting control method for HRB500E steel, comprising the following steps:

[0008] Molten iron and scrap steel are fed into a converter for converter smelting.

[0009] 1) Using the first gun position, within 2 minutes of starting the oxygen supply, add lime, raw dolomite, and dust removal ash briquettes;

[0010] 2) Using the second gun position, within 2-5 minutes of oxygen supply, lower the gun position to the third gun position, and add dust removal ash briquettes and / or lime according to the slag situation;

[0011] 3) Using the fourth gun position, add dust removal ash briquettes and / or lime within 5-11 minutes of oxygen supply, then lower the gun position to the fifth gun position;

[0012] The scrap steel includes steel chip briquettes and / or shavings briquettes;

[0013] The steel chip briquettes and / or shaving briquettes account for 60% to 70% of the mass of the scrap steel.

[0014] 4) Using the pressurized lance position, converter smelting is carried out during the oxygen supply process from 11 minutes to the final lance lifting.

[0015] Preferably, the temperature of the molten iron is 1370~1470℃;

[0016] The composition of the molten iron, by mass ratio, includes: 4.0%~5.0% carbon, 0.20%~0.50% silicon, 0.20%~45% manganese, 0.10%~0.15% phosphorus, with the balance being iron;

[0017] The amounts of lime, raw dolomite, and dust removal ash briquettes added are controlled and calculated based on the temperature and composition of the molten iron and the control requirements of HRB500E steel.

[0018] Preferably, in the control requirements of the HRB500E steel grade, the phosphorus content is ≤0.035% by mass;

[0019] The control requirements for HRB500E steel grade specify a chromium content of 0.10% to 0.22% by mass.

[0020] The HRB500E steel grade includes the HRB500E series steel grades.

[0021] Preferably, the total amount of lime added is 20~25 kg / t steel;

[0022] The total amount of raw dolomite added is 5~10 kg / t steel;

[0023] The first gun position is 1800~1850mm.

[0024] Preferably, the time for adding lime, raw dolomite and dust removal ash briquettes is 1 minute 40 seconds to 1 minute 50 seconds after the blowing begins;

[0025] The amount of lime added in step 1) is 80% to 90% of the total amount of lime added;

[0026] The amount of dust removal ash briquettes added in step 1) is 40% to 60% of the total amount of dust removal ash briquettes added.

[0027] Preferably, the oxygen supply intensity in step 1) is 28,000~30,000 m³ / h. 3 / h;

[0028] The second gun position is 1400~1800mm;

[0029] In step 2), from 2 minutes 20 seconds to 2 minutes 40 seconds, the gun position begins to be lowered, and from 4 minutes 20 seconds to 4 minutes 40 seconds, it is lowered to the third gun position;

[0030] The third gun position is 1400~1500mm.

[0031] Preferably, in step 2), dust removal ash briquettes and / or lime are added after 3-5 minutes;

[0032] In step 2), the dust removal ash briquettes and / or lime are added in one or multiple batches.

[0033] In the aforementioned multiple batches, the amount added in each batch is 1~3 kg / t of steel;

[0034] The oxygen supply intensity in step 2) is 30,000~33,000 m³ / h. 3 / h.

[0035] Preferably, the step of selecting to add dust removal ash briquettes and / or lime according to the slag removal situation specifically means: adding dust removal ash briquettes when the slag removal effect is poor; adding lime when the slag is active.

[0036] The fourth gun position is 1200~1500mm;

[0037] In step 3), after 6 minutes, add dust removal ash briquettes and / or lime.

[0038] Preferably, in step 3), the method of adding dust ash briquettes and / or lime includes adding them in small batches in multiple batches;

[0039] In step 3), the dust removal ash briquettes are added in multiple batches, with the amount of each batch of dust removal ash briquettes controlled at 1~3 kg / t steel and the interval time controlled at 50~70 seconds.

[0040] In step 3), the lime is added in one or more batches, and the amount added is controlled at 1~3 kg / t steel.

[0041] In step 3), the gun position is lowered starting at 10-11 minutes.

[0042] Preferably, the fifth gun position is 1200~1250mm;

[0043] The oxygen supply intensity in step 3) is 32000~35000 m³ / h. 3 / h;

[0044] The sixth gun position is 1100~1200mm;

[0045] The oxygen supply intensity in step 4) is 30,000~32,000 m³ / h. 3 / h;

[0046] The smelting time using the pressurized gun position shall not be less than 50 seconds.

[0047] This invention provides a converter smelting control method for HRB500E steel, comprising the following steps: molten iron and scrap steel are fed into the converter for converter smelting; firstly, using the first lance position, oxygen is supplied for 2 minutes, and lime, raw dolomite, and dust removal ash briquettes are added; then, using the second lance position, oxygen is supplied for 2-5 minutes, and the lance position is lowered to the third lance position, and dust removal ash briquettes and / or lime are added according to the slag formation; then, using the fourth lance position, oxygen is supplied for 5-11 minutes, and dust removal ash briquettes and / or lime are added, and then the lance position is lowered to the fifth lance position; the scrap steel includes steel chip briquettes and / or shavings briquettes; the steel chip briquettes and / or shavings briquettes account for 60%-70% of the mass of the scrap steel; finally, using the lowered lance position, converter smelting is carried out during the oxygen supply period from 11 minutes to the final lance lifting. Compared with existing technologies, this invention specifically selects steel chip briquettes and / or shavings briquettes for use in the converter smelting control method for HRB500E steel. These two types of scrap steel have a high chromium content, which can increase their proportion in the furnace and thus increase the chromium content in the molten iron. This invention optimizes the proportion of scrap steel added during converter smelting, and by optimizing the converter smelting control process, increases the residual chromium ratio in the initial smelting of the steel, thereby reducing the amount of chromium alloys added and lowering alloy costs. This invention does not require adjustments to the steel composition or changes to subsequent rolling processes, and also ensures stable rolled product performance.

[0048] This invention provides a converter smelting control method for producing HRB500E series steels. The addition of high-chromium-content scrap materials such as steel chip briquettes (or shaving briquettes) is increased from 10% to 60-70%. While maintaining the total amount of scrap steel, the addition of steel rebar briquettes and heavy-duty scrap materials is correspondingly reduced. By adjusting the slag-forming, oxygen-supplying, and endpoint processes, the method achieves early initial slag formation, thorough slag formation during the process, and sticky final slag, thereby significantly increasing the chromium content in the initial molten steel. The residual chromium content in the converter's initial molten steel is significantly increased, while the addition of chromium alloys is reduced, resulting in a significant reduction in alloy costs.

[0049] This invention increases the chromium content in the furnace feed by altering the proportions of different types of scrap steel used in the production of chromium-containing microalloyed HRB500E series steels. Simultaneously, it involves specific adjustments and designs to the converter smelting operation to ensure an increase in the residual chromium content in the final primary molten steel. This invention significantly improves the residual chromium ratio in the primary molten steel, thereby reducing the amount of chromium alloys required and resulting in a substantial reduction in alloy costs. Furthermore, the process is simple, highly controllable, and stable, making it more suitable for industrial-scale promotion and application. Detailed Implementation

[0050] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention and not for limiting the claims of the present invention.

[0051] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0052] There are no particular restrictions on the purity of any raw materials used in this invention. Preferably, industrial-grade pure or conventionally pure materials used in the smelting of HRB500E steel are sufficient.

[0053] All raw materials of this invention are conventional in the field, and each brand name and abbreviation is clear and distinct in its relevant application. Those skilled in the art can purchase them from the market or prepare them by conventional methods based on the brand name, abbreviation and corresponding application.

[0054] This invention provides a converter smelting control method for HRB500E steel, comprising the following steps:

[0055] Molten iron and scrap steel are fed into a converter for converter smelting.

[0056] 1) Using the first gun position, within 2 minutes of starting the oxygen supply, add lime, raw dolomite, and dust removal ash briquettes;

[0057] 2) Using the second gun position, within 2-5 minutes of oxygen supply, lower the gun position to the third gun position, and add dust removal ash briquettes and / or lime according to the slag situation;

[0058] 3) Using the fourth gun position, add dust removal ash briquettes and / or lime within 5-11 minutes of oxygen supply, then lower the gun position to the fifth gun position;

[0059] The scrap steel includes steel chip briquettes and / or shavings briquettes;

[0060] The steel chip briquettes and / or shaving briquettes account for 60% to 70% of the mass of the scrap steel.

[0061] 4) Using the pressurized lance position, converter smelting is carried out during the oxygen supply process from 11 minutes to the final lance lifting.

[0062] This invention involves feeding molten iron and scrap steel into a converter for smelting. Specifically, scrap steel can be added first, followed by molten iron.

[0063] The present invention first uses the first gun position, and within 2 minutes of starting the oxygen supply, lime, raw dolomite and dust removal ash briquettes are added.

[0064] In this invention, the temperature of the molten iron is preferably 1370~1470℃, more preferably 1390~1450℃, and even more preferably 1410~1430℃.

[0065] In this invention, the composition of the molten iron, by mass ratio, preferably includes: 4.0%~5.0% carbon, 0.20%~0.50% silicon, 0.20%~45% manganese, 0.10%~0.15% phosphorus, with the balance being iron. More preferably, it includes 4.2%~4.8% carbon, 0.25%~0.45% silicon, 1%~30% manganese, and 0.11%~0.14% phosphorus. More preferably, it includes 4.4%~4.6% carbon, 0.3%~0.4% silicon, 5%~15% manganese, and 0.12%~0.13% phosphorus.

[0066] In this invention, the amount of lime, raw dolomite, and dust removal ash briquettes added is preferably controlled and calculated according to the control requirements of molten iron temperature, composition, and HRB500E steel grade.

[0067] In this invention, the phosphorus content in the HRB500E steel grade is preferably ≤0.035%, more preferably 0.01%~0.03%, and even more preferably 0.015%~0.025%.

[0068] In this invention, the mass content of chromium is preferably 0.10% to 0.22%, more preferably 0.12% to 0.2%, and even more preferably 0.14% to 0.18%.

[0069] In this invention, the HRB500E steel grade preferably includes HRB500E series steel grades.

[0070] In this invention, the total amount of lime added is preferably 20~25 kg / t steel, more preferably 21~24 kg / t steel, and even more preferably 22~23 kg / t steel.

[0071] In this invention, the total amount of raw dolomite added is preferably 5~10 kg / t steel, more preferably 6~9 kg / t steel, and even more preferably 7~8 kg / t steel.

[0072] In this invention, the first gun position is preferably 1800~1850mm, more preferably 1810~1840mm, and even more preferably 1820~1830mm.

[0073] In this invention, the preferred time for adding lime, raw dolomite and dust removal ash briquettes is 1 minute 40 seconds to 1 minute 50 seconds after the blowing begins, more preferably 1 minute 42 seconds to 1 minute 48 seconds, and even more preferably 1 minute 44 seconds to 1 minute 46 seconds.

[0074] In this invention, the amount of lime added in step 1) is preferably 80% to 90% of the total amount of lime added, more preferably 82% to 88%, and even more preferably 84% to 86%.

[0075] In this invention, the amount of dust removal ash briquettes added in step 1) is preferably 40% to 60% of the total amount of dust removal ash briquettes added, more preferably 44% to 56%, and even more preferably 48% to 52%.

[0076] In this invention, the oxygen supply intensity in step 1) is preferably 28,000~30,000 m³ / h. 3 / h, more preferably 28400~29600m 3 / h, more preferably 28800~29200m 3 / h.

[0077] In this invention, the second gun position is used. Within 2 to 5 minutes of oxygen supply, the gun position is lowered to the third gun position. Depending on the slag situation, dust removal ash briquettes and / or lime are added.

[0078] In this invention, the second gun position is preferably 1400~1800mm, more preferably 1450~1750mm, more preferably 1500~1700mm, and even more preferably 1550~1650mm.

[0079] In this invention, in step 2), preferably, the gun position is lowered from 2 minutes 20 seconds to 2 minutes 40 seconds, and then lowered to the third gun position from 4 minutes 20 seconds to 4 minutes 40 seconds; more preferably, the gun position is lowered from 2 minutes 24 seconds to 2 minutes 36 seconds, and then lowered to the third gun position from 4 minutes 24 seconds to 4 minutes 36 seconds; even more preferably, the gun position is lowered from 2 minutes 28 seconds to 2 minutes 32 seconds, and then lowered to the third gun position from 4 minutes 28 seconds to 4 minutes 32 seconds.

[0080] In this invention, the third gun position is preferably 1400~1500mm, more preferably 1420~1480mm, and even more preferably 1440~1460mm.

[0081] In this invention, in step 2), preferably, dust removal ash briquettes and / or lime are added after 3 to 5 minutes, more preferably after 3.4 to 4.6 minutes, and even more preferably after 3.8 to 4.2 minutes.

[0082] In this invention, in step 2), the dust removal ash briquettes and / or lime are preferably added in one or multiple batches.

[0083] In this invention, the amount added in each batch of the multiple batches is preferably 1~3 kg / t steel, more preferably 1.4~2.6 kg / t steel, and even more preferably 1.8~2.2 kg / t steel.

[0084] In this invention, the oxygen supply intensity in step 2) is preferably 30,000~33,000 m³ / h. 3 / h, more preferably 30500~32500m 3 / h, more preferably 31000~32000m 3 / h.

[0085] In this invention, the step of selecting to add dust removal ash briquettes and / or lime based on the slag-raising situation is preferably as follows: when the slag-raising effect is poor, dust removal ash briquettes are added; when the slag is active, lime is added. Specifically, the slag-raising effect can be comprehensively judged based on one or more of the following technical means: flue gas analysis system, CO curve analysis, and audio-based slag treatment.

[0086] The present invention then uses the fourth gun position, and within 5 to 11 minutes of oxygen supply, adds dust removal ash briquettes and / or lime, and then lowers the gun position to the fifth gun position;

[0087] The scrap steel includes steel chip briquettes and / or shavings briquettes;

[0088] The steel chip briquettes and / or shaving briquettes account for 60% to 70% of the mass of the scrap steel.

[0089] In this invention, the scrap steel includes steel chip briquettes and / or shavings briquettes, preferably steel chip briquettes or shavings briquettes.

[0090] In this invention, the steel chip briquettes and / or shaving briquettes account for 60% to 70% of the mass of the scrap steel, which can be 62% to 68% or 64% to 66%.

[0091] In this invention, the fourth gun position is preferably 1200~1500mm, more preferably 1250~1450mm, and even more preferably 1300~1400mm.

[0092] In this invention, in step 3), preferably after 6 minutes, dust removal ash briquettes and / or lime are added.

[0093] In this invention, in step 3), the method of adding dust ash briquettes and / or lime preferably includes adding in small batches in multiple batches.

[0094] In this invention, in step 3), the dust removal ash briquettes are added in multiple batches. The amount of dust removal ash briquettes added in each batch is preferably controlled at 1~3 kg / t steel, the interval time is preferably controlled at 50~70 seconds, more preferably at 1.4~2.6 kg / t steel, the interval time is preferably controlled at 54~66 seconds, more preferably at 1.8~2.2 kg / t steel, and the interval time is preferably controlled at 58~62 seconds.

[0095] In this invention, in step 3), the lime is added in one or more batches, preferably at a rate of 1~3 kg / t steel, more preferably at a rate of 1.4~2.6 kg / t steel, and even more preferably at a rate of 1.8~2.2 kg / t steel.

[0096] In this invention, in step 3), it is preferable to start lowering the gun position at 10-11 minutes, more preferably at 10.2-10.8 minutes, and even more preferably at 10.4-10.6 minutes.

[0097] In this invention, the fifth gun position is preferably 1200~1250mm, more preferably 1210~1240mm, and even more preferably 1220~1230mm.

[0098] In this invention, the oxygen supply intensity in step 3) is preferably 32000~35000 m³ / h. 3 / h, more preferably 32500~34500m 3 / h, more preferably 33000~34000m 3 / h.

[0099] In this invention, the sixth gun position is preferably 1100~1200mm, more preferably 1120~1180mm, and even more preferably 1140~1160mm.

[0100] The present invention finally adopts the pressurized lance position, and the converter smelting is carried out during the oxygen supply 11 minutes to the end point of lance lifting.

[0101] In this invention, the oxygen supply intensity in step 4) is preferably 30,000~32,000 m³ / h. 3 / h, more preferably 30400~31600m 3 / h, more preferably 30800~31200m 3 / h.

[0102] In this invention, the smelting time using the pressurized gun position is preferably not less than 50 seconds, more preferably not less than 60 seconds, and even more preferably not less than 90 seconds.

[0103] This invention aims to complete and refine the overall technical solution, better optimize the design of the scrap steel type and proportion for furnace feeding, better optimize the converter smelting control process, and better reduce the amount of chromium alloys added. Specifically, the converter smelting control method for the aforementioned chromium-containing microalloyed HRB500E series steel grades may include the following:

[0104] The converter smelting control method for chromium-containing microalloyed HRB500E series steel grades provided by this invention includes the following steps:

[0105] (1) Prepare steel chip briquettes (or shavings briquettes) in advance according to the production plan of HRB500E series steel grades;

[0106] (2) During production, the proportion of steel chip briquettes (or shavings briquettes) in each bucket of scrap steel is adjusted from 10% to 60-70%;

[0107] (3) Calculate the amount of lime, raw dolomite and dust removal ash briquettes to be added based on the temperature and composition of the molten iron and the control requirements of HRB500E series steel grades;

[0108] (4) Process smelting control:

[0109] S1. Start blowing for 2 minutes, using a gun position of 1800-1850mm. Begin feeding at 1 minute 40 seconds to 1 minute 50 seconds, adding 80-90% lime, all of the raw dolomite, and 40-60% dust collector briquettes. The oxygen supply intensity is 28,000-30,000 m³ / h. 3 / h;

[0110] S2. Oxygen supply for 2-5 minutes, using a lance position of 1400-1800mm. Gradually lower the lance over approximately 2 minutes and 30 seconds, and lower it to the blowing lance position of 1400-1500mm over approximately 4 minutes and 30 seconds. Depending on the initial slag removal situation, add dust removal ash briquettes or lime every 3-5 minutes. Add dust removal ash briquettes if the slag removal effect is poor, and add lime if the slag is active. The oxygen supply intensity is 30,000-33,000 m³ / h. 3 / h;

[0111] S3. Oxygen supply for 5-11 minutes, using a lance position of 1200mm-1500mm. The remaining lime and cold material are added gradually after 6 minutes, following a small-batch, multi-batch addition pattern. When blowing reaches 10-11 minutes, gradually lower the lance, ensuring it is lowered to 1200-1250mm before TSC measurement, with an oxygen supply intensity of 32000-35000 m³. 3 / h;

[0112] S4. Oxygen supply for 11 minutes – end point: gun lifting, using a gun position of 1100–1200 mm, oxygen supply intensity of 30,000–32,000 m³ / h. 3 / h.

[0113] Specifically, in step (2), steel chip briquettes (or shavings briquettes) account for 60-70% of the total amount of scrap steel per bucket.

[0114] Specifically, in step (3), the temperature of the molten iron is 1370-1470℃; the composition of the molten iron is: carbon 4.0-5.0%, silicon 0.20-0.50%, manganese 0.20-45%, and phosphorus 0.10-0.15%.

[0115] Specifically, in step (3), the endpoint control conditions for HRB500E series steel are: endpoint phosphorus content ≤ 0.035%, endpoint chromium 0.10~0.22%, and temperature 1610~1640℃.

[0116] Specifically, in step (3), the amount of lime added is calculated to be 20-25 kg / t steel according to the slag alkalinity requirements, and the amount of raw dolomite is 5-10 kg / t steel.

[0117] Specifically, in step S1, lime, raw dolomite, and dust removal ash briquettes are all added in one batch.

[0118] Specifically, in step S2, the dust removal ash briquettes (or lime) are added in 1 to 2 batches, with the amount added in each batch controlled at 1 to 3 kg / t steel.

[0119] Specifically, in step S3, the remaining dust removal ash briquettes are added in batches, with the amount of each batch of dust removal ash briquettes controlled at 1-3 kg / t steel and the interval time controlled at 50-70 s; the remaining lime is added in 1-2 batches, with the amount of each batch controlled at 1-3 kg / t steel.

[0120] Specifically, in step S4, the final press time is not less than 50 seconds.

[0121] This invention provides a converter smelting control method for HRB500E series steels with chromium-containing microalloying. Specifically, this invention selects steel shavings and / or wood chips as scrap types for converter smelting control of HRB500E steels. These two types of scrap have a high chromium content, allowing for an increase in their proportion added to the furnace and thus increasing the chromium content in the molten iron. This invention optimizes the proportion of scrap types added during converter smelting, improving the residual chromium ratio in the initial smelting of the steel, thereby reducing the amount of chromium alloys added and lowering alloy costs. This invention eliminates the need to adjust the steel composition or modify subsequent rolling processes, while also ensuring stable rolled product performance.

[0122] This invention provides a converter smelting control method for producing HRB500E series steels. The addition of high-chromium-content scrap materials such as steel chip briquettes (or shaving briquettes) is increased from 10% to 60-70%. While maintaining the total amount of scrap steel, the addition of steel rebar briquettes and heavy-duty scrap materials is correspondingly reduced. By adjusting the slag-forming, oxygen-supplying, and endpoint processes, the method achieves early initial slag formation, thorough slag formation during the process, and sticky final slag, thereby significantly increasing the chromium content in the initial molten steel. The residual chromium content in the converter's initial molten steel is significantly increased, while the addition of chromium alloys is reduced, resulting in a significant reduction in alloy costs.

[0123] This invention increases the chromium content in the furnace feed by altering the proportions of different types of scrap steel used in the production of chromium-containing microalloyed HRB500E series steels. Simultaneously, it involves specific adjustments and designs to the converter smelting operation to ensure an increase in the residual chromium content in the final primary molten steel. This invention significantly improves the residual chromium ratio in the primary molten steel, thereby reducing the amount of chromium alloys required and resulting in a substantial reduction in alloy costs. Furthermore, the process is simple, highly controllable, and stable, making it more suitable for industrial-scale promotion and application.

[0124] To further illustrate the present invention, the following describes in detail a converter smelting control method for HRB500E steel provided by the present invention with reference to embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. They are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0125] Example 1

[0126] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-1 steel. The process involves 129.2 tons of molten iron and 37.9 tons of scrap steel, including 24.5 tons of steel briquettes. The molten iron temperature is 1430℃, and its composition is: carbon 4.09%, silicon 0.29%, manganese 0.22%, and phosphorus 0.104%. The auxiliary material consumption for this furnace is: 2952 kg of lime, 1138 kg of raw dolomite, and 1152 kg of dust collection ash briquettes.

[0127] The blowing nozzle was initially positioned at 1850mm. At 1 minute 40 seconds, 514kg of dust collector briquettes were added; at 1 minute 45 seconds, 2510kg of lime and 1138kg of raw dolomite were added, resulting in an oxygen supply intensity of 28500m³ / h. At 2 minutes 40 seconds, the nozzle was lowered to 1800mm; at 2 minutes 55 seconds, it was lowered to 1750mm; at 3 minutes, 202kg of lime was added; at 3 minutes 15 seconds, the nozzle was lowered to 1700mm; at 3 minutes 40 seconds, it was lowered to 1650mm; at 3 minutes 50 seconds, 240kg of lime was added; at 4 minutes, the nozzle was lowered to 1600mm; at 4 minutes 15 seconds, it was lowered to 1550mm; at 4 minutes 40 seconds, it was lowered to 1... At 500mm, the oxygen supply intensity was 30600 m³ / h; at 5 minutes and 30 seconds, the nozzle was lowered to 1450mm; at 6 minutes, 160 kg of dust collector briquettes were added; at 7 minutes and 05 seconds, 157 kg of dust collector briquettes were added; at 7 minutes and 55 seconds, 162 kg of dust collector briquettes were added; at 9 minutes, 159 kg of dust collector briquettes were added; at 10 minutes, the nozzle was lowered to 1400mm; at 10 minutes and 40 seconds, the nozzle was lowered to 1350mm, with an oxygen supply intensity of 32300 m³ / h; at 11 minutes and 35 seconds, the nozzle was lowered to 1250mm; at 12 minutes and 05 seconds, the nozzle was lowered to 1200mm, with an oxygen supply intensity of 30050 m³ / h. The total oxygen supply time was 790 seconds, the final temperature was 1612℃, and the final phosphorus content was 0.033% and chromium content was 0.151%.

[0128] Example 2

[0129] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-1 steel. The process yields 128.9 tons of molten iron and 36.8 tons of scrap steel, including 25.1 tons of steel shavings briquettes. The molten iron temperature is 1415℃, and its composition is: carbon 4.27%, silicon 0.32%, manganese 0.25%, and phosphorus 0.117%. The auxiliary material consumption for this furnace is: 3320 kg of lime, 1068 kg of raw dolomite, and 1750 kg of dust collection ash briquettes.

[0130] The blowing nozzle was initially positioned at 1800mm. At 1 minute 40 seconds, 830kg of dust collector briquettes were added; at 1 minute 50 seconds, 2855kg of lime and 1068kg of raw dolomite were added, resulting in an oxygen supply intensity of 28300 m³ / h. At 2 minutes 30 seconds, the nozzle was lowered to 1750mm; at 3 minutes 30 seconds, it was lowered to 1700mm again; at 3 minutes 20 seconds, 240kg of lime was added; at 3 minutes 40 seconds, it was lowered to 1650mm; at 4 minutes 10 seconds, it was lowered to 1600mm; at 4 minutes 30 seconds, 225kg of lime was added; at 4 minutes 45 seconds, it was lowered to 1500mm, resulting in an oxygen supply intensity of 31000 m³ / h. At 5 minutes 10 seconds, the nozzle was lowered to 1450mm; at 6 minutes... 160 kg of dust collector briquettes were added at 15 seconds, 285 kg at 7 minutes and 10 seconds, the nozzle was raised to 1500 mm at 7 minutes and 20 seconds, 300 kg at 8 minutes, and 175 kg at 8 minutes and 50 seconds. The nozzle was lowered to 1450 mm at 9 minutes and 30 seconds, and to 1350 mm at 10 minutes and 30 seconds, with an oxygen supply intensity of 32550 m³ / h. The nozzle was then lowered to 1250 mm at 11 minutes and 30 seconds, to 1200 mm at 11 minutes and 45 seconds, to 1150 mm at 12 minutes and 50 seconds, and to 1100 mm at 13 minutes, with an oxygen supply intensity of 30600 m³ / h. The total oxygen supply time was 830 seconds, the final temperature was 1615℃, and the final phosphorus and chromium content were 0.026% and 0.149%, respectively.

[0131] Example 3

[0132] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-2 steel. The process involves 129.1 tons of molten iron and 37.1 tons of scrap steel, including 24.7 tons of steel briquettes. The molten iron temperature is 1391℃, and its composition is: carbon 4.36%, silicon 0.41%, manganese 0.27%, and phosphorus 0.125%. The auxiliary material consumption for this furnace is: 3632 kg of lime, 817 kg of raw dolomite, and 1032 kg of dust collection ash briquettes.

[0133] The blowing nozzle was set to 1810mm. At 1 minute 50 seconds, 413kg of dust collector briquettes were added; at 1 minute 55 seconds, 2918kg of lime and 817kg of raw dolomite were added, resulting in an oxygen supply intensity of 28300m³ / h. At 2 minutes 45 seconds, the nozzle was lowered to 1760mm. At 3 minutes 05 seconds, 222kg of lime was added; at 3 minutes 50 seconds, 236kg of lime was added; at 4 minutes, the nozzle was lowered to 1660mm; at 4 minutes 10 seconds, it was lowered to 1610mm; at 4 minutes 20 seconds, 256kg of lime was added; at 4 minutes 30 seconds, the nozzle was lowered to 1510mm; at 4 minutes 45 seconds... The oxygen supply intensity was 31,700 m³ / h when the nozzle was lowered to 1460 mm in 6 minutes and 5 seconds; 200 kg of dust collector briquettes were added at 7 minutes and 5 seconds; 208 kg of dust collector briquettes were added at 8 minutes; the nozzle was lowered to 1410 mm in 9 minutes, with an oxygen supply intensity of 32,510 m³ / h; the nozzle was lowered to 1360 mm in 11 minutes, 1310 mm in 11 minutes and 15 seconds; 1210 mm in 11 minutes and 30 seconds; and 1160 mm in 12 minutes, with an oxygen supply intensity of 30,130 m³ / h. The total oxygen supply time was 775 seconds, the final temperature was 1617℃, and the final phosphorus and chromium concentrations were 0.030% and 0.133%, respectively.

[0134] Example 4

[0135] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-1 steel. The process involves 128.3 tons of molten iron and 38.1 tons of scrap steel, including 26.6 tons of steel shavings briquettes. The molten iron temperature is 1442℃, and its composition is: carbon 4.25%, silicon 0.22%, manganese 0.24%, and phosphorus 0.131%. The auxiliary material consumption for this furnace is: 2768 kg of lime, 900 kg of raw dolomite, and 1771 kg of dust collection briquettes.

[0136] The blowing gun was positioned at 1830mm. At 1 minute 45 seconds, 710kg of dust collector briquettes were added; at 1 minute 50 seconds, 2491kg of lime and 900kg of raw dolomite were added, resulting in an oxygen supply intensity of 28410m³ / h. At 2 minutes 25 seconds, the gun was lowered to 1780mm; at 2 minutes 45 seconds, it was lowered to 1730mm; at 3 minutes 13 seconds, 203kg of dust collector briquettes were added; at 3 minutes 47 seconds, the gun was lowered to 1680mm; at 4 minutes, 177kg of dust collector briquettes were added; at 4 minutes 10 seconds, the gun was lowered to 1580mm; at 4 minutes 30 seconds, it was lowered to 1480mm; and at 4 minutes 50 seconds, 277kg of lime was added. g, oxygen supply intensity 31200 m3 / h; 5 minutes 10 seconds lower the nozzle to 1430 mm, 6 minutes 23 seconds add 198 kg of dust collector briquettes, 7 minutes 18 seconds add 201 kg of dust collector briquettes, 8 minutes 25 seconds add 282 kg of dust collector briquettes, 9 minutes lower the nozzle to 1380 mm, 10 minutes 50 seconds lower the nozzle to 1330 mm, oxygen supply intensity 33120 m3 / h; 11 minutes 05 seconds lower the nozzle to 1280 mm, 11 minutes 45 seconds lower the nozzle to 1180 mm, 12 minutes 40 seconds lower the nozzle to 1150 mm, oxygen supply intensity 30520 m3 / h. Oxygen supply time 813 seconds, endpoint temperature 1624℃, endpoint phosphorus 0.031%, chromium 0.161%.

[0137] Example 5

[0138] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-2 steel. The process involves 128.8 tons of molten iron and 37.2 tons of scrap steel, including 24.2 tons of steel briquettes. The molten iron temperature is 1428℃, and its composition is: carbon 4.43%, silicon 0.39%, manganese 0.23%, and phosphorus 0.141%. The auxiliary material consumption for this furnace is: 3513 kg of lime, 1289 kg of raw dolomite, and 1584 kg of dust collection ash briquettes.

[0139] At position 1800mm, 790kg of dust collector briquettes were added at 1 minute 40 seconds; 3160kg of lime and 1289kg of raw dolomite were added at 1 minute 45 seconds, resulting in an oxygen supply intensity of 28220 m³ / h. At 2 minutes 30 seconds, 153kg of lime was added; the nozzle was lowered to 1750mm at 2 minutes 35 seconds; it was lowered to 1700mm at 3 minutes 30 seconds; 200kg of lime was added at 3 minutes 30 seconds; the nozzle was lowered to 1650mm at 3 minutes 50 seconds; it was lowered to 1600mm at 4 minutes 15 seconds; and it was lowered to 1500mm at 4 minutes 40 seconds, resulting in an oxygen supply intensity of 31560 m³ / h. m³ / h; 263 kg of dust collector briquettes were added at 6 minutes and 12 seconds, 255 kg at 7 minutes and 15 seconds, and 276 kg at 8 minutes and 23 seconds. The nozzle was lowered to 1450 mm at 8 minutes and 45 seconds, 1400 mm at 9 minutes and 30 seconds, and 1350 mm at 10 minutes and 45 seconds, with an oxygen supply intensity of 32130 m³ / h; the nozzle was lowered to 1250 mm at 11 minutes and 33 seconds, 1200 mm at 11 minutes and 45 seconds, and 1150 mm at 12 minutes and 30 seconds, with an oxygen supply intensity of 31200 m³ / h. The oxygen supply time was 803 seconds, the final temperature was 1631℃, and the final phosphorus content was 0.029% and chromium content was 0.135%.

[0140] Comparative Example 1

[0141] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-1 steel. The process involves 128.7 tons of molten iron and 37.8 tons of scrap steel, including 3.8 tons of steel shavings briquettes. The molten iron temperature is 1443℃, and its composition is: carbon 4.24%, silicon 0.30%, manganese 0.27%, and phosphorus 0.121%. The auxiliary material consumption for this furnace is: 3695 kg of lime, 1403 kg of raw dolomite, and 2815 kg of dust collection ash briquettes.

[0142] The blowing nozzle was initially positioned at 1820mm. At 1 minute 45 seconds, 1130kg of dust collector briquettes were added; at 1 minute 50 seconds, 2956kg of lime and 1403kg of raw dolomite were added, resulting in an oxygen supply intensity of 28240 m³ / h. The nozzle was lowered to 1770mm at 2 minutes 25 seconds, then to 1720mm at 2 minutes 55 seconds. At 3 minutes, 333kg of lime was added; at 3 minutes 35 seconds, the nozzle was lowered to 1650mm; at 3 minutes 57 seconds, 227kg of lime was added; at 4 minutes 15 seconds, the nozzle was lowered to 1550mm; and at 4 minutes 44 seconds, it was lowered to 1500mm, resulting in an oxygen supply intensity of 316... 30 m³ / h; 5 minutes 30 seconds to lower the nozzle to 1450 mm, 6 minutes to add 433 kg of dust collector briquettes, 7 minutes 05 seconds to add 421 kg of dust collector briquettes, 8 minutes 11 seconds to add 425 kg of dust collector briquettes, 9 minutes 07 seconds to add 406 kg of dust collector briquettes, 10 minutes to add 179 kg of lime, 10 minutes 43 seconds to lower the nozzle to 1350 mm, oxygen supply intensity 32110 m³ / h; 11 minutes 53 seconds to lower the nozzle to 1230 mm, 12 minutes 55 seconds to lower the nozzle to 1170 mm, oxygen supply intensity 30230 m³ / h. Oxygen supply time 798 seconds, endpoint temperature 1630℃, endpoint phosphorus 0.025%, chromium 0.042%.

[0143] Comparative Example 2

[0144] This embodiment describes a converter smelting control method for chromium-containing microalloyed HRB500E series steel grades, producing HRB500E-1 steel. The process involves 129.9 tons of molten iron and 37.4 tons of scrap steel, including 4.5 tons of steel shavings briquettes. The molten iron temperature is 1431℃, and its composition is: carbon 4.44%, silicon 0.25%, manganese 0.32%, and phosphorus 0.115%. The auxiliary material consumption for this furnace is: 2884 kg of lime, 1031 kg of raw dolomite, and 2532 kg of dust collection ash briquettes.

[0145] With the blowing lance at 1800mm, 1053kg of dust collector briquettes were added at 1 minute 40 seconds, followed by 2451kg of lime and 1031kg of raw dolomite at 1 minute 45 seconds, resulting in an oxygen supply intensity of 28130m³ / h. At 2 minutes 30 seconds, the lance was lowered to 1750mm, followed by 233kg of lime at 2 minutes 55 seconds, then lowered to 1700mm at 3 minutes, 1650mm at 3 minutes 43 seconds, 200kg of lime at 4 minutes 02 seconds, then lowered to 1550mm at 4 minutes 10 seconds, and finally to 1500mm at 4 minutes 33 seconds, resulting in an oxygen supply intensity of 32050m³ / h. / h; at 5 minutes and 30 seconds, the nozzle was lowered to 1450mm; at 6 minutes and 05 seconds, 401kg of dust collector briquettes were added; at 7 minutes, 370kg of dust collector briquettes were added; at 8 minutes and 06 seconds, 359kg of dust collector briquettes were added; at 9 minutes, 349kg of dust collector briquettes were added; at 10 minutes, the nozzle was lowered to 1400mm; at 10 minutes and 28 seconds, the nozzle was lowered to 1350mm, with an oxygen supply intensity of 33100m³ / h; at 11 minutes and 50 seconds, the nozzle was lowered to 1300mm; at 12 minutes, the nozzle was lowered to 1250mm; at 13 minutes, the nozzle was lowered to 1200mm, with an oxygen supply intensity of 30790m³ / h. The oxygen supply time was 803 seconds, the final temperature was 1617℃, and the final phosphorus and chromium content were 0.033% and 0.035%, respectively.

[0146] The following is a comparison of the residual chromium and high-chromium alloy consumption in the initial smelting of steel in Examples 1-5 and Comparative Examples 1-2:

[0147]

[0148] As can be seen from the table above, when producing chromium-containing microalloyed HRB500E series steels, optimizing the design of the scrap steel type and ratio in the furnace and optimizing the converter smelting control process can significantly increase the residual chromium ratio in the initial smelting of molten steel, thereby reducing the amount of chromium alloys added and significantly reducing alloy costs.

[0149] The above provides a detailed description of a converter smelting control method for chromium-containing microalloyed HRB500E series steels provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the embodiments above are merely to help understand the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the wording of the claims, or if they include equivalent structural elements that are not substantially different from the wording of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A converter smelting control method for HRB500E steel, characterized in that, Includes the following steps: Molten iron and scrap steel are fed into a converter for converter smelting. The composition of the molten iron, by mass ratio, includes: 4.0%~5.0% carbon, 0.20%~0.50% silicon, 0.20%~45% manganese, 0.10%~0.15% phosphorus, with the balance being iron; 1) Using the first gun position, within 2 minutes of starting the oxygen supply, add lime, raw dolomite, and dust removal ash briquettes; The total amount of lime added is 20~25 kg / t steel; The total amount of raw dolomite added is 5~10 kg / t steel; The first gun position is 1800~1850mm; The amount of lime added in step 1) is 80% to 90% of the total amount of lime added; The amount of dust collector briquettes added in step 1) is 40% to 60% of the total amount of dust collector briquettes added; The oxygen supply intensity in step 1) is 28,000~30,000 m³ / h. 3 / h; 2) Using the second gun position, within 2-5 minutes of oxygen supply, lower the gun position to the third gun position, and add dust removal ash briquettes and / or lime according to the slag situation; The second gun position is 1400~1800mm; The third gun position is 1400~1500mm; The oxygen supply intensity in step 2) is 30,000~33,000 m³ / h. 3 / h; 3) Using the fourth gun position, add dust removal ash briquettes and / or lime within 5-11 minutes of oxygen supply, then lower the gun position to the fifth gun position; The fourth gun position is 1200~1500mm; The scrap steel includes steel chip briquettes and / or shavings briquettes; The steel chip briquettes and / or shaving briquettes account for 60% to 70% of the mass of the scrap steel. The fifth gun position is 1200~1250mm; The oxygen supply intensity in step 3) is 32000~35000 m³ / h. 3 / h; 4) Using the pressurized lance position, converter smelting is carried out during the oxygen supply process from 11 minutes to the final lance lifting; The oxygen supply intensity in step 4) is 30,000~32,000 m³ / h. 3 / h.

2. The converter smelting control method according to claim 1, characterized in that, The temperature of the molten iron is 1370~1470℃; The amounts of lime, raw dolomite, and dust removal ash briquettes added are controlled and calculated based on the temperature and composition of the molten iron and the control requirements of HRB500E steel.

3. The converter smelting control method according to claim 2, characterized in that, The control requirements for HRB500E steel grade stipulate that the phosphorus content is ≤0.035% by mass. The control requirements for HRB500E steel grade specify a chromium content of 0.10% to 0.22% by mass. The HRB500E steel grade includes the HRB500E series steel grades.

4. The converter smelting control method according to claim 1, characterized in that, The time for adding lime, raw dolomite, and dust removal ash briquettes is 1 minute 40 seconds to 1 minute 50 seconds after the blowing begins.

5. The converter smelting control method according to claim 1, characterized in that, In step 2), the gun position begins to decrease from 2 minutes 20 seconds to 2 minutes 40 seconds, and then decreases to the third gun position from 4 minutes 20 seconds to 4 minutes 40 seconds.

6. The converter smelting control method according to claim 1, characterized in that, In step 2), after 3 to 5 minutes, add dust removal ash briquettes and / or lime.

7. The converter smelting control method according to claim 1, characterized in that, In step 2), the dust removal ash briquettes and / or lime are added in one or multiple batches. In the aforementioned multiple batches, the amount added in each batch is 1~3 kg / t of steel.

8. The converter smelting control method according to claim 1, characterized in that, The specific steps for adding dust removal ash briquettes and / or lime based on the slag removal situation are as follows: when the slag removal effect is poor, add dust removal ash briquettes; when the slag is active, add lime. In step 3), after 6 minutes, add dust removal ash briquettes and / or lime.

9. The converter smelting control method according to claim 1, characterized in that, In step 3), the method of adding dust ash briquettes and / or lime includes adding them in small batches in multiple batches; In step 3), the dust removal ash briquettes are added in multiple batches, with the amount of each batch of dust removal ash briquettes controlled at 1~3 kg / t steel and the interval time controlled at 50~70 seconds. In step 3), the lime is added in one or more batches, and the amount added is controlled at 1~3 kg / t steel. In step 3), the gun position is lowered starting at 10-11 minutes.

10. The converter smelting control method according to claim 1, characterized in that, The gun position is 1100~1200mm; The smelting time using the pressurized gun position shall not be less than 50 seconds.

Images