Converter blowing process for extracting vanadium from molten iron

Abstract

The present application relates to the technical field of steel metallurgy, and particularly relates to a converter blowing process of vanadium extraction molten iron. The converter blowing process provided by the present application is started from vanadium extraction molten iron, and the process of vanadium extraction, semi-steel treatment and converter blowing is controlled, especially the oxygen lance position control and oxygen flow control in the converter blowing process, and the sectional fan flow control of primary flue gas and the evaporative cooler temperature control, so that the particulate emission concentration in the primary flue gas diffusion process of the converter is reduced, which is beneficial to reducing the particulate emission.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, specifically a converter blowing process for extracting vanadium from molten iron. Background Technology

[0002] Dry dust removal technology is of great significance for controlling particulate matter emitted from primary flue gas in converters, mainly in the following aspects: Environmental benefits: Dry dust removal technology can effectively reduce the concentration of particulate matter in flue gas, which aligns with the concept of green environmental protection. For example, after adopting dry dust removal technology, the flue gas emission concentration (standard state) can reach 10 mg / m³. 3 The following measures will help reduce air pollution and protect the environment and public health.

[0003] Economic benefits: Dry dust collection technology not only reduces environmental pollution but also improves resource utilization efficiency. For example, fine dust collected by the dust collector can be recycled, reducing production costs. Furthermore, dry dust collection technology can increase gas recovery, bringing additional economic benefits to enterprises.

[0004] Social Benefits: The promotion of dry dust removal technology helps raise environmental awareness and technological awareness across society. It is not only a manifestation of corporate social responsibility but also an important means of promoting the sustainable development of the entire industry.

[0005] In conclusion, the dry dust removal process for controlling particulate matter emissions from primary flue gas in converters not only has significant environmental and economic benefits, but also promotes sustainable social development. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a converter blowing process for vanadium extraction molten iron. The process provided by the present invention can effectively reduce the emission concentration of particulate matter emitted from primary flue gas during converter blowing, thereby reducing particulate matter emissions.

[0007] This invention provides a dry dust removal process for converter steelmaking, comprising the following steps: Vanadium-containing molten iron is subjected to vanadium extraction to obtain vanadium-extracted molten iron. Then, the vanadium-extracted molten iron is subjected to semi-steel treatment to obtain vanadium-extracted semi-steel. The vanadium-extracted semi-steel and auxiliary raw materials are then subjected to converter blowing. When the molten steel in the steelmaking furnace has a [C] ≤ 0.30% and a temperature of 1600℃~1640℃, carbon is removed. The primary flue gas generated from vanadium extraction and the primary flue gas generated from converter blowing are cooled by an evaporative cooler and then drawn into an electrostatic precipitator by a fan for dry dust removal. The material obtained from the dry dust removal is then released through a venting system. During the converter blowing process, the oxygen lance position is controlled in the following manner: The oxygen lance position is controlled at 1550 mm to 1650 mm in the early stage of the converter blowing process, 1750 mm to 1850 mm in the middle stage, and 1150 mm to 1250 mm in the later stage. Oxygen flow is controlled during the converter blowing process in the following manner: Control oxygen flow rate to 7000 m³ 3 h -1 ~9000 m 3 h -1 Initiate partial oxygen blowing, increasing the oxygen flow rate to 15000 m³ / s within 90 seconds. 3 h -1 ~16000 m 3 h -1 During the full oxygen blowing process, the oxygen flow rate is reduced to 7000 m³ within 60 seconds before the carbon extraction. 3 h -1 ~9000m 3 h -1 After carbon extraction, the oxygen flow rate is controlled at 7000 m³. 3 h -1 ~9000 m 3 h -1 Perform supplemental oxygen blowing.

[0008] This invention treats vanadium-containing molten iron through a process of vanadium extraction, semi-steel processing, and converter blowing. It controls the oxygen lance position and oxygen flow rate during converter blowing, and simultaneously cools and dry-dust-removes the primary flue gas generated during vanadium extraction and converter blowing. Finally, the material obtained after dry dust removal is released. This reduces particulate matter emissions during primary flue gas release while ensuring smelting safety and flue gas composition safety. In particular, the control of oxygen lance position and oxygen flow rate during converter blowing effectively controls the rate of temperature rise in the molten pool, preventing severe slag re-drying and large-scale splashing, and ensuring a stable CO reaction.

[0009] Specifically, this invention first extracts vanadium from vanadium-containing molten iron to obtain vanadium-extracted molten iron, and then processes the vanadium-extracted molten iron into semi-steel to obtain vanadium-extracted semi-steel. The vanadium-containing molten iron used in this invention is a common type of vanadium-containing molten iron in the art. This invention does not impose any special limitations on the vanadium extraction process; it is a common vanadium extraction process in the art. The semi-steel processing of this invention involves adding ferrosilicon to the vanadium-extracted molten iron, and discharging the material when the semi-steel temperature is ≤1400℃ and the carbon content of the semi-steel is 3.30% ≤ carbon ≤ 3.60%. The amount of ferrosilicon added in this invention is the sum of the standard amount of ferrosilicon added and the additional amount of ferrosilicon added. The standard amount of ferrosilicon added is 275~325 kg / ton of the vanadium-extracted semi-steel, preferably 300 kg / ton of the vanadium-extracted semi-steel. The additional amount of ferrosilicon added is determined in kg by calculating the value obtained by the formula {(1400+360)-molten iron temperature-molten iron carbon} ÷ 100 × 70. Here, molten iron carbon refers to the carbon content in the molten iron.

[0010] After obtaining vanadium-extracted semi-steel, the present invention performs converter blowing with the vanadium-extracted semi-steel and auxiliary raw materials. Specifically, the present invention mixes the vanadium-extracted semi-steel with iron, then starts oxygen blowing and ignites the furnace. After successful ignition, waits at least 1 minute, and then adds auxiliary raw materials in multiple batches within 11 minutes.

[0011] More specifically, after oxygen blowing begins, the lance is first ignited at a position of 2.2 m, held for 1 minute, and then lowered to the blowing point while still ignited. If the lance remains at 2.2 m without ignition for 20 seconds, it must be lifted. After lifting, the furnace should be shaken before nitrogen blowing for 30-60 seconds, and the blower speed should be >800 rpm before the lance can be lowered again for blowing. Furthermore, if the vanadium-extracted semi-steel is mixed with iron and the converter returns to zero for >15 minutes without being lowered for blowing, the furnace must be shaken back and forth before the lance can be lowered for blowing.

[0012] To prevent the formation of explosive gases, this invention does not lower the hood during the first minute of the initial blowing process. Instead, it employs an oxygen-enriched combustion method to fully convert CO into CO2. The high concentration of CO2 gas isolates CO from the air, thereby preventing the formation of explosive gases. In some embodiments of this invention, the fan hood is not lowered during the first minute of the initial blowing process, and then lowered to at least 60%.

[0013] The auxiliary materials described in this invention include scrap steel, slag-forming material, coolant, and iron-carbon balls. Since the converter blowing process in this invention uses low-flow-rate blowing, to ensure successful ignition, the proportion of lumpy scrap steel in the scrap steel must be >20%, and the proportion of light and thin scrap steel in the scrap steel must not exceed 50% of the total scrap steel. The scrap steel described in this invention is strictly classified; scrap steel mixed with grease or non-ferrous metals, and damp scrap steel are strictly prohibited from being fed into the furnace. If, under special circumstances, the scrap steel does not meet the requirements, the furnace is shaken before and after the initial blowing and nitrogen blowing is performed in a 60-second mode; for furnaces with added scrap steel, the furnace is shaken to -30°C before blowing (except for thin-plate furnaces) and then the blowing is initiated at the zero position. The iron-carbon balls, cold-pressed briquettes (coolant), active lime (slag-forming material), ferrosilicon, quicklime, high-magnesium raw materials, etc., described in this invention must be dry and have low dust content.

[0014] After successful ignition, this invention requires a waiting period of at least 1 minute before adding auxiliary materials in multiple batches within 11 minutes, avoiding splashing during the addition process. Specifically, the multiple batch addition method involves adding ≤2000 kg of each material; 2 tons of iron-carbon balls are added in one batch, and if more iron-carbon balls are needed, they can only be added again after 5 minutes. During the blowing process, concentrated addition of the slag-forming material should be avoided. Preferably, each batch of slag-forming material is 500-1000 kg; the amount of slag-forming material added should reach at least 90% of the total slag-forming material to prevent a rapid increase or decrease in temperature that could lead to an increase in CO content. The coolant added at one time should reach at least 50% of the total coolant volume. When adding scrap steel, if the carbon content and temperature are high (carbon ≥ 3.60% and temperature ≥ 1350℃), the addition of scrap steel should be strictly calculated according to the process requirements and heat balance to control the initial converter temperature to not exceed 1380℃. If the process requires the addition of scrap steel but scrap steel is unavailable, additional heats can be added. Nitrogen should be purged for 30-60 seconds first, and slag-forming material should be added during the nitrogen purging process. In this invention, adding material is prohibited within 3 minutes before carbon extraction in the converter.

[0015] The converter blowing process described in this invention employs oxygen lance position control and oxygen flow rate control. Oxygen flow rate and lance position are important parameters in the blowing process. The lance position directly controls the degree of stirring of the molten pool and affects the CO concentration in the flue gas; the oxygen flow rate directly affects the decarburization rate.

[0016] Specifically, in the converter blowing process described in this invention, oxygen lance position control is required in the early, middle, and late stages of converter blowing. The calculation begins one minute after successful ignition. The early stage of converter blowing refers to the period before the 6th minute after blowing begins; the middle stage refers to the 6th to 10th minute after blowing begins; and the late stage refers to the 10th to 13th minute after blowing begins. The oxygen lance position is controlled at 1550 mm to 1650 mm, preferably 1600 mm, in the early stage; 1750 mm to 1850 mm, preferably 1800 mm, in the middle stage; and 1150 mm to 1250 mm, preferably 1200 mm, in the late stage. A higher lance position is used in the early stage to ensure good slag formation and thorough melting; the carbon-oxygen reaction is intense in the middle and late stages, so the lance position should not be too low to prevent slag from drying out; the lance position is gradually lowered before the end of the process to homogenize the steel composition. By controlling the gun position, the temperature of the molten pool can be controlled to rise steadily, preventing back-drying and splashing, preventing dust collector explosion, and improving the endpoint hit rate, reducing make-up blowing, avoiding deep blowing, and reducing the total iron content of the final slag.

[0017] During the converter blowing process described in this invention, oxygen flow rate also needs to be controlled in the following manner: the oxygen flow rate is controlled at 7000 m³ / s. 3 h -1 ~9000 m 3 h -1 Initiate partial oxygen blowing, increasing the oxygen flow rate to 15000 m³ / s within 90 seconds. 3 h -1 ~16000 m 3 h -1 During the full oxygen blowing process, the oxygen flow rate is reduced to 7000 m³ before the carbon extraction. 3 h -1 ~9000 m 3 h -1 After carbon extraction, the oxygen flow rate is controlled at 7000 m³. 3 h -1 ~9000 m 3 h -1 Oxygen supplementation is performed. This invention adjusts the duration and gradient of low oxygen flow rate based on different raw material conditions. Specifically, the oxygen flow rate control in this invention employs semi-oxygen blowing, followed by low-oxygen-pressure blowing within 90 seconds after semi-oxygen blowing, with the oxygen pressure gradually increasing to the specified oxygen flow rate value for full-oxygen blowing (i.e., ramping oxygen blowing to full-oxygen blowing). This ensures that the oxygen supply intensity matches the CO chemical reaction rate within the furnace, guaranteeing safe flue gas composition. Simultaneously, the alarm points for process lance lifting are downgraded and strictly limited to mid-term lance lifting. During the converter blowing process described in this invention, reducing the oxygen flow rate before carbon removal (i.e., implementing oxygen release operation) can reduce the CO and O2 content in the flue gas.

[0018] In the converter blowing process described in this invention, carbon removal is performed when the molten steel [C] in the steelmaking furnace is ≤0.30% and the temperature is 1600℃~1640℃. High carbon removal is strictly prohibited. In some embodiments of this invention, supplementary blowing (oxygen lance blowing again) is required after carbon removal, and the oxygen flow rate must be controlled during supplementary blowing. In addition, if abnormal lance lifting occurs during the converter blowing process described in this invention, for steel grades that do not require nitrogen, the furnace should be shaken first, then nitrogen should be blown for 30~60 seconds before lowering the lance; for steel grades that require nitrogen, 50~100 kg of ferrosilicon must be added, the furnace should be shaken back and forth, and the lance should be lowered for blowing after 3 minutes. Adding materials is prohibited during the nitrogen blowing process; if abnormal lance lifting occurs twice during the blowing process, after the second and subsequent lance lifting, the furnace should be shaken first and then nitrogen should be blown for 30~60 seconds. The lance can only be lowered for blowing again when the blower speed is >800 rpm. After abnormal lance lifting occurs during the blowing process, the blower should be immediately reduced to a low speed or the process should be paused. If a leak occurs and the lance is lifted, the furnace should be shaken first, then nitrogen should be blown for 60 seconds. Only when the CO content is 0% and the blower speed is >800 rpm can the lance be lowered for blowing again.

[0019] This invention cools the primary flue gas generated from vanadium extraction and the primary flue gas generated from converter blowing in an evaporative cooler, and then draws it into an electrostatic precipitator for dry dust removal by a fan. This invention uses the fan to control the flow rate of the primary flue gas in segments. The fan speed control consists of a hood pressure controller and a flow controller. The set value of the flue gas flow rate is modified by a proportional regulator based on the hood pressure and oxygen flow rate. The parameters involved are as follows: set flue gas flow rate [Nm3(dry) / h], oxygen flow rate [Nm3 / h], hood flue gas flow rate [Nm3(dry) / h]. When the auxiliary materials are not added, the flue gas flow rate is controlled according to Formula 1; when the auxiliary materials are added, the flue gas flow rate is adjusted according to Formula 2. Formula 1 is: Flue gas flow rate = (Oxygen flow rate) / ... 2.1438) + Smoke hood gas flow rate; Formula 2 is: Smoke flow rate = (Oxygen flow rate) 2.1438 1.07) + flue gas flow rate from the fume hood. During normal production, the blower speeds at each stage of the blowing process operate in a centralized automatic mode to meet the automatic adjustment of blower speeds at different stages of the converter. Ensuring the blower speed is within a suitable range guarantees both dust removal efficiency and minimizes CO combustion, maximizing CO recovery.

[0020] This invention simultaneously cools and dry-dust-removes the primary flue gas generated during vanadium extraction and converter blowing. An evaporative cooler (EC) is used for cooling, with the water spray volume from the EC nozzles controlled by a constant target temperature of 260°C at the EC outlet and a safe temperature range of 240-280°C. The water flow rate is finely adjusted by a temperature open-loop controller based on the deviation between the set and actual EC outlet temperatures, using continuous PLC control. The controller's process value (process value) is used as the temperature TEVC-OUT. Through control optimization, the EC outlet temperature is stably controlled within a narrow range, effectively solving the problem of unstable EC outlet temperature.

[0021] This invention cools and dry-dust-removes the primary flue gas generated during vanadium extraction and converter blowing, and then releases the material obtained from the dry dust removal through a venting system, effectively reducing the particulate matter emission concentration during the primary flue gas venting process of the converter and reducing particulate matter emissions.

[0022] This invention relates to the field of iron and steel metallurgy technology, specifically a converter blowing process for vanadium extraction. The converter blowing process provided by this invention, starting from vanadium extraction molten iron, reduces particulate matter emission concentration during the primary flue gas venting process by controlling the vanadium extraction, semi-steel processing, and converter blowing process, particularly the oxygen lance position and oxygen flow control during converter blowing, as well as the segmented fan flow control and evaporative cooler temperature control of the primary flue gas. Attached Figure Description

[0023] Figure 1 This is a diagram showing the control of the gun position as a function of blowing time in the process of this invention. Figure 2 This is a graph showing the control of oxygen supply flow rate as a function of blowing time in the process of this invention. Figure 3 This is a diagram showing the changing patterns of flue gas composition during converter smelting. Detailed Implementation

[0024] This invention discloses a converter blowing process for extracting vanadium from molten iron. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0025] The present invention will be further described below with reference to the embodiments: Example 1 In the converter smelting process of a steel plant, the hood is not lowered for 1 minute during the initial blowing stage. Oxygen-enriched combustion ensures that all CO is converted into CO2. The high concentration of CO2 isolates CO from the air, thus preventing the formation of explosive gases. During the middle stage of smelting, the oxygen lance position and flow rate are stabilized, and the rate of temperature rise in the molten pool is rationally controlled to prevent severe slag drying and large-scale splashing, ensuring a stable C-O reaction. When raw materials containing iron oxide or carbon are added, the oxygen supply flow rate must be adjusted to effectively avoid the formation of mixed explosive gases.

[0026] The converter smelting process described above generates primary flue gas. After being cooled and conditioned by an evaporative cooler, the primary flue gas is stably drawn into an electrostatic precipitator by an ID fan for dry dust removal. Finally, the material obtained after dry dust removal is released through a venting system. Through the above control, particulate matter emissions during the primary flue gas venting process of the converter are reduced.

[0027] The specific plan is as follows: 1. Control of charging and slag-making processes (1) Raw material requirements: Due to the low-flow start-up, to ensure successful ignition, the proportion of lumpy scrap steel in the furnace must be greater than 20%. Scrap steel must be strictly classified, and it is strictly prohibited to mix it with grease, non-ferrous metals, or damp scrap steel. Light and thin scrap steel must not exceed 50% of the total scrap steel. A refined material policy must be implemented for raw materials entering the furnace. Raw materials such as iron-carbon balls, cold-pressed briquettes (coolant), active lime (slag-forming material), ferrosilicon, quicklime, and high-magnesium materials must be dry and have low dust content.

[0028] (2) Process control: After tapping iron from the blast furnace, a steel plant performs vanadium extraction to obtain vanadium-extracting molten iron. This vanadium-extracting molten iron is first processed into semi-steel to obtain vanadium-extracting semi-steel, then mixed with quicklime and high-magnesium alloys to form iron. Scrap steel, slag-forming materials, coolant, and iron-carbon balls are then added for converter blowing. During the blowing process, the oxygen lance position and oxygen supply flow rate are controlled. The specific process is as follows: S1) Semi-steel treatment: Add ferrosilicon to each furnace of vanadium-containing molten iron, 300 kg of ferrosilicon per furnace, with a minimum of 100 kg of ferrosilicon per furnace. Add more as appropriate according to the molten iron conditions (the amount added is calculated according to the following formula: {(1400+360)-molten iron temperature-molten iron carbon}÷100×70 (kg)); semi-steel temperature ≤1400℃, semi-steel carbon control range: 3.30%≤carbon≤3.60%.

[0029] S2) Before adding iron: Add 2 tons each of quicklime and high magnesium to the converter.

[0030] S3) When adding iron: Add vanadium-extracting semi-steel into the converter.

[0031] S4) After mixing iron: Put down the gun and start blowing. Do not add any material first. First, ignite the fire. After the fire is successfully ignited, wait for 1 minute.

[0032] S5) Blowing Stage: After igniting the flame and waiting for 1 minute at the beginning of blowing, add scrap steel, slag-forming material, coolant, iron-carbon balls, etc. in multiple batches. The amount of each material added should be ≤2000kg, and the amount of iron-carbon balls should be 2000kg per batch. If more iron-carbon balls are needed, they can be added again after 5 minutes. All cold materials (scrap steel, slag-forming material, coolant, iron-carbon balls, etc.) must be added within 11 minutes of oxygen blowing. Adding materials is prohibited 3 minutes before carbon removal. Avoid concentrated addition of slag-forming material during blowing. The amount added in each batch should be controlled between 500 and 1000kg. The amount of coolant added at one time in the early stage should reach more than 50% of the total amount, and the amount of slag-forming material added should reach more than 90% of the total amount to avoid a rapid increase or decrease in temperature that would cause an increase in CO content.

[0033] Precautions during the blowing process: ① If the carbon content and temperature are both high (carbon ≥ 3.60% and temperature ≥ 1350℃), strictly follow the process requirements and calculate the heat balance to determine whether scrap steel needs to be added to control the initial converter temperature to not exceed 1380℃; ② If the process requires the addition of scrap steel, but there is no scrap steel available for the next heat, first blow nitrogen for 30-60 seconds, adding slag-forming material during the nitrogen blowing process; ③ If, under special circumstances, the scrap steel does not meet the requirements, use the pre-and-post furnace shaking and 60-second nitrogen blowing mode; for heats where scrap steel is added, shake the furnace to -30°C at the back of the furnace before starting blowing (except for thin plate heats) and then return it to zero before starting blowing; ④ Prevent splashing during the charging process, and control the process separately before, during, and after iron addition, during the blowing stage, the tapping stage, and the slag splashing stage.

[0034] 2. Oxygen lance operation process control

[0035] The converter employs variable lance position and flow rate control, with flow rate and lance position being crucial parameters in the blowing process. The lance position directly controls the agitation of the molten pool, affecting the CO concentration in the flue gas; the oxygen flow rate directly influences the decarburization rate. Proper control of lance position and flow rate is key to normal smelting and is also a critical aspect of controlling dry dust removal and explosion venting in the converter.

[0036] (1) Precautions: ①After the iron is mixed, start the gun in semi-automatic mode.

[0037] ② After oxygen is turned on, the lance should remain at 2.2m for 1 minute, and then, with the flame ignited, the oxygen lance should be lowered to the blowing point. If the lance remains at 2.2m for 20 seconds without ignition, it must be lifted. After lifting the lance, the furnace should be shaken first, and then nitrogen should be blown for 30-60 seconds. Only when the blower speed is >800 rpm can the lance be lowered again for blowing.

[0038] ③ If there is an abnormal lifting of the lance during the blowing process, for steel grades that do not require nitrogen, shake the furnace first, then blow nitrogen for 30-60 seconds before removing the lance; for steel grades that require nitrogen, 50-100 kg of ferrosilicon must be added, shake the furnace back and forth, and remove the lance after 3 minutes for blowing. Adding materials is prohibited during the nitrogen blowing process.

[0039] ④ If two abnormal lance liftings occur during the blowing process, after the second and subsequent lance liftings, shake the furnace first and then blow nitrogen for 30-60 seconds. Only when the blower speed is >800 rpm can the lance be lowered for blowing again.

[0040] ⑤ After the explosion occurs and the lance is lifted, shake the furnace first and then blow nitrogen for 60 seconds. When the CO content is 0% and the blower speed is >800 rpm, the lance can be lowered for blowing again.

[0041] ⑥ If the blower is lifted abnormally during the blowing process, the operator should immediately reduce the speed of the blower to low or click "wait".

[0042] ⑦ If the converter returns to zero and blowing is not performed within 15 minutes, the lance must be moved back and forth before blowing can begin.

[0043] (2) Oxygen lance position control during the blowing stage: This invention employs a higher lance position in the early stages to ensure thorough slag formation. In the middle and later stages, when the carbon-oxygen reaction is intense, the lance position should not be too low to prevent slag from drying out. Before the final stage, the lance position is gradually lowered to homogenize the steel composition. By controlling the lance position, the molten pool temperature is controlled to rise steadily, preventing drying out and splashing, and preventing dust collector explosions.

[0044] Prior to this invention, based on the empirical formula for oxygen lance working position H = (30~40) × D_outlet, the working position of the oxygen lance at Xichang Steel & Vanadium was calculated to be 1.8~2.4m. In semi-steelmaking, to reduce the total iron content in the slag, the lance position should be appropriately lowered in the later stages. However, according to on-site observations, the oxygen lance position control at Xichang Steel & Vanadium fluctuated significantly in the early stages of production. The lance position was around 2.3~3.0m in the early stages of smelting, controlled at 2.0~2.5m in the middle stages, and generally at 1.8~2.2m in the later stages. Therefore, in this invention, based on the empirical formula for oxygen lance working position and combined with the characteristics of Xigang Vanadium semi-steelmaking, the operating position of the oxygen lance in steelmaking is appropriately reduced. Specifically, in the early stage of smelting (before the 6th minute after blowing begins), lance position fluctuations are reduced, and the working lance position is controlled at approximately 1.6 m. In the middle stage (6-10 minutes after blowing begins), the lance position is still controlled at 1.6 m in the early stage and 1.8 m in the later stage. In the late stage (10-13 minutes after blowing begins), the lance position is still controlled at 1.8 m in the early stage and 1.2 m in the later stage. This helps to improve the endpoint hit rate, reduce supplementary blowing, avoid deep blowing, and reduce the total iron content in the final slag. The specific lance position control process is as follows: Figure 1 As shown, Figure 1 This is a diagram showing the control of the gun position as a function of blowing time in the process of this invention.

[0045] (3) Oxygen flow control during the blowing stage: Based on different raw material conditions, adjust the duration and gradient of low oxygen flow rate. Use low oxygen pressure blowing during the first 1.5 minutes of converter blowing, gradually increasing the oxygen pressure to the specified value to ensure the oxygen supply intensity matches the C-O chemical reaction rate in the furnace, guaranteeing safe flue gas composition. Simultaneously, downgrade and classify the process lance lifting alarm points, strictly limiting mid-stage lance lifting. Reduce the range for carbon removal, strictly prohibiting high carbon removal. Carbon removal should only be performed when the [C] content of the molten steel in the steelmaking furnace is ≤0.30% and the temperature is 1600℃~1640℃. Details are as follows: Oxygen flow control employs a semi-oxygen start-up, transitioning to full-oxygen blowing within 1.5 minutes through an incline process to ensure complete combustion of CO into CO2. Before pulling the carbon and lifting the lance, an oxygen release operation is performed to reduce the oxygen flow rate, thereby lowering the CO and O2 content in the flue gas. The oxygen supply flow rate is then controlled according to the blowing time, such as... Figure 2 As shown, Figure 2 This is a diagram showing the oxygen supply flow rate control over the blowing time in the process of this invention. Carbon is removed when the [C] content in the molten steel is ≤0.30% and the temperature is 1600℃~1640℃. After removing the carbon and lifting the lance, supplementary blowing is performed. During supplementary blowing, the carbon content in the furnace is ≥0.30%, and the oxygen flow rate must be reduced to 8000. Supplementary blowing is completed after approximately 70 seconds of blowing.

[0046] The variation pattern of flue gas composition during converter smelting is shown in Figure 3 As shown, Figure 3 This diagram illustrates the changing patterns of flue gas composition during converter smelting. In the initial blowing stage, the molten iron temperature is low, inhibiting the decarburization reaction, with oxidation of silicon and manganese being the dominant process, and CO and CO2 contents being low. In the middle blowing stage, the carbon-oxygen reaction intensifies, and CO and CO2 contents begin to rise rapidly, with the highest decarburization rate reaching 0.4%~0.6% per minute. The CO2 content reaches an initial peak, and the CO content stabilizes at around 60%~70%, making explosions highly likely. In the later blowing stage, the carbon content is low, the carbon-oxygen reaction rate slows down, and the decarburization rate is approximately 0.12%~0.18% per minute, with the amount of flue gas produced also decreasing accordingly. Understanding the decarburization patterns during converter smelting is of significant guiding importance for preventing explosions. By optimizing the converter smelting process and specifically controlling the process, explosions caused by dust collectors can be completely avoided.

[0047] 3. Control process after primary flue gas generation: The aforementioned blowing stage generates primary flue gas. This primary flue gas is first drawn in by an ID fan and treated by an evaporative cooler, then by an electrostatic precipitator, and finally released after exiting the electrostatic precipitator. Details are as follows: (1) ID fan speed control During the blowing stage, the blower speed control consists of two different types of controllers: a fume hood pressure controller and a flow controller. During the blowing stage, the fume hood is lowered by at least 60%, and the setpoint for the flue gas flow rate is modified by a proportional controller based on the fume hood pressure and oxygen flow rate. Flow rate is controlled in segments according to different stages, and the final parameters are determined as follows: setpoint flue gas flow rate [Nm3(dry) / h], oxygen flow rate [Nm3 / h], fume hood flue gas flow rate [Nm3(dry) / h], setpoint flue gas flow rate = (oxygen flow rate...) / h. 2.1438) + smoke flow rate from the fume hood; For the blowing stage, when auxiliary materials (scrap steel, slag-forming material, coolant, iron-carbon balls, etc.) are added, the speed controller setpoint is calculated according to the following formula: Set flow rate = (Oxygen flow rate) 2.1438 1.07) + smoke flow rate of the fume hood.

[0048] During normal production, the blower speeds at each stage of the blowing process must operate in centralized automatic mode to meet the automatic adjustment of blower speeds at different stages of the converter. Maintaining the blower speed within a suitable range ensures effective dust removal while minimizing CO combustion and maximizing CO recovery.

[0049] (2) Evaporative Cooler (EC) Control

[0050] ① Determining the water spray volume of the EC nozzle: The system operates based on a constant EC outlet temperature setting of 260℃, with a safe temperature control range of 240~280℃. The water flow rate is finely adjusted by the open-loop temperature controller through continuous PLC control based on the deviation between the set value and the actual value of the EC outlet temperature. The controller's process value (technical value) is used as the temperature TEVC-OUT.

[0051] ②EC control effect: By optimizing the control, the EC outlet temperature is stably controlled within a narrow range, effectively solving the problem of unstable EC outlet temperature.

[0052] After the above processes, the compliance rate of ultra-low emission processes reached 100%; the compliance rate of comprehensive emissions of major pollutants was 99.86%.

[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A converter blowing process for extracting vanadium-containing molten iron, characterized in that, Includes the following steps: Vanadium-containing molten iron is subjected to vanadium extraction to obtain vanadium-extracted molten iron. Then, the vanadium-extracted molten iron is subjected to semi-steel treatment to obtain vanadium-extracted semi-steel. The vanadium-extracted semi-steel and auxiliary raw materials are then subjected to converter blowing. When the molten steel [C] ≤ 0.30% and the temperature is 1600℃~1640℃, carbon is removed. The primary flue gas generated from vanadium extraction and the primary flue gas generated from converter blowing are cooled by an evaporative cooler and then drawn into an electrostatic precipitator by a fan for dry dust removal. The material obtained from the dry dust removal is then released through a venting system. During the converter blowing process, the oxygen lance position is controlled in the following manner: The oxygen lance position is controlled at 1550 mm to 1650 mm in the early stage of the converter blowing process, 1750 mm to 1850 mm in the middle stage, and 1150 mm to 1250 mm in the later stage. Oxygen flow is controlled during the converter blowing process in the following manner: Control oxygen flow rate to 7000 m³ 3 h -1 ~9000 m 3 h -1 Initiate partial oxygen blowing, increasing the oxygen flow rate to 15000 m³ / s within 90 seconds. 3 h -1 ~16000 m 3 h -1 During the full oxygen blowing process, the oxygen flow rate is reduced to 7000 m³ within 60 seconds before the carbon extraction. 3 h -1 ~9000 m 3 h -1 After carbon extraction, the oxygen flow rate is controlled at 7000 m³. 3 h -1 ~9000 m 3 h -1 Perform supplemental oxygen blowing.

2. The process according to claim 1, characterized in that, The early stage of converter blowing is before the 6th minute after blowing starts, the middle stage of converter blowing is from the 6th to the 10th minute after blowing starts, and the late stage of converter blowing is from the 10th to the 13th minute after blowing starts.

3. The process according to claim 1, characterized in that, The semi-steel processing specifically involves adding ferrosilicon to the vanadium-extracting molten iron, and discharging the material when the semi-steel temperature is ≤1400℃ and the carbon content of the semi-steel is 3.30%≤carbon≤3.60%.

4. The process according to claim 3, characterized in that, The amount of ferrosilicon added is the sum of the standard amount of ferrosilicon added and the additional amount of ferrosilicon added. The standard amount of ferrosilicon added is 275~325 kg / ton of the vanadium-extracting semi-steel. The additional amount of ferrosilicon added is determined in kg by calculating the value obtained by the formula {(1400+360)-molten iron temperature-molten iron carbon}÷100×70.

5. The process according to claim 1, characterized in that, The converter blowing process specifically involves: The vanadium-extracting semi-steel is mixed with iron, then oxygen is blown in, and then ignition is initiated. After successful ignition, wait at least 1 minute, and then add auxiliary materials in multiple batches within 11 minutes. The auxiliary materials include scrap steel, slag-forming material, coolant, and iron-carbon balls.

6. The process according to claim 5, characterized in that, The specific method of adding materials in multiple batches is as follows: the total amount of each material added is ≤2000kg, the iron-carbon balls are added in batches of 2 tons, and the amount of slag-forming material added in each batch is 500~1000kg; The amount of coolant added at one time reaches more than 50% of the total amount of coolant, and the amount of slag-forming material added reaches more than 90% of the total amount of slag-forming material.

7. The process according to claim 1, characterized in that, The fan's skirt does not lower during the first minute of the initial blowing operation.

8. The process according to claim 7, characterized in that, The fan's hood does not lower for the first minute after the start of blowing, and then lowers to at least 60%.

9. The process according to claim 1, characterized in that, When the auxiliary raw materials are not added, the flow rate of the primary flue gas is controlled by the fan according to Formula 1. When the auxiliary raw materials are added, the flow rate of the primary flue gas is adjusted by the fan according to Formula 2. Formula 1 is: Flue gas flow rate = (Oxygen flow rate) 2.1438) + smoke flow rate from the fume hood; Formula 2 is: Flue gas flow rate = (Oxygen flow rate) 2.1438 1.07) + smoke flow rate of the fume hood.

10. The process according to claim 1, characterized in that, The water spray volume of the evaporative cooler is controlled according to the outlet temperature of the evaporative cooler of 260°C and the safe temperature control range of 240~280°C.

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