A method for predicting the silicon content of molten iron charged into a converter and controlling the charging of materials

Abstract

This invention discloses a method for predicting silicon content in molten iron and controlling charging in a converter, comprising: (1) after adding scrap steel and molten iron to the converter, lowering the oxygen lance to start blowing; when the nitrogen content in the flue gas begins to decrease and the carbon dioxide content begins to rise synchronously, recording the time, defined as the start time t1 of the flue gas analysis system; (2) starting from time t1, sequentially recording the CO content in the converter flue gas at 1-second intervals, defined as W. iCO (3) The CO content W recorded two minutes before the start of blowing for this furnace. iCO The average CO content W was obtained by averaging. ACO Using formula W Si =-0.018W ACO +0.768 Calculate the silicon content value W in molten iron. Si This invention analyzes the variation of flue gas composition during converter smelting under different silicon contents in the molten iron, establishes a silicon content prediction model, and thus guides the charging operation, achieving precise operation of converter smelting and improving the converter dephosphorization effect and temperature control accuracy.

Description

Technical Field

[0001] This invention relates to a method for predicting silicon content in molten iron during converter smelting and for controlling the feeding process, belonging to the technical field of steelmaking. Background Technology

[0002] For converter smelting processes, the silicon content of the molten iron directly affects the oxygen supply and charging systems during smelting, ultimately impacting the dephosphorization effect and temperature control accuracy. In actual converter smelting, issues such as molten iron ladle consolidation and delayed sample delivery of desulfurized molten iron lead to inaccurate or missing silicon content data after the converter starts blowing. This affects operators' handling of adding lime and coolant, thus impacting dephosphorization and temperature control. In recent years, flue gas analysis technology has been gradually applied in the field of converter smelting. For example, patent application CN111518980A discloses a correction method and system for a converter endpoint carbon content prediction model, and patent application CN108647407A discloses a method for determining carbon content by analyzing flue gas in converter steelmaking. The above methods mainly analyze the changes in CO and CO2 content in the flue gas during the smelting process to dynamically control converter smelting and predict endpoint components. However, the above patents failed to use the flue gas analysis results to calculate the silicon content of the molten iron fed into the converter, thereby achieving precise control of the charging process in converter smelting. Summary of the Invention

[0003] To address the aforementioned problems, this invention discloses a method for predicting silicon content in molten iron during converter smelting and controlling the charging process. Utilizing flue gas composition information from the converter smelting process, a method for predicting the silicon content in the molten iron is established, providing guidance for operators in converter charging operations and improving converter smelting efficiency. The specific technical solution is as follows: A method for predicting silicon content in molten iron and controlling charging in a converter, applicable to converter production processes equipped with a flue gas analysis system, comprising the following steps: (1) After the converter is filled with scrap steel and molten iron, and the furnace body is straightened, the oxygen lance is lowered to start blowing. During the blowing process, the nitrogen content and carbon dioxide content will gradually change. When the nitrogen content in the flue gas begins to decrease and the carbon dioxide content begins to rise synchronously, the carbon-oxygen reaction begins to occur in the furnace, and the carbon in the molten pool begins to be oxidized. Record the time and define this time as the start time of the flue gas analysis system t1, s. (2) Starting from time t1, record the CO content in the converter flue gas at 1-second intervals, and define it as W. iCO , % represents the CO content in the flue gas at time i, % (3) For this furnace, the first two minutes from t1, i.e., t1~t 120 The recorded CO volume content value W iCO The average CO content W was obtained by averaging.ACO And store the average value in the database; (4) Read the W value of this furnace from the data storage. ACO %,%; using the iron-silicon content prediction model W Si =-0.018W ACO +0.768 Calculate the mass content of silicon W in molten iron. Si ,%.

[0004] Furthermore, the total amount of lime added W during the converter smelting process 石灰 =2057 + 3500W Si , kg; Total amount of pellets added W 球团 =-14839+50.9HM_WGT+7.69 HM_TEP-53.9SCRAP_WGT+ 4116 W Si HM_WGT represents the weight of molten iron entering the furnace, in kg; SCRAP_WGT represents the weight of scrap steel, in t; HM_TEP represents the temperature of molten iron entering the furnace, in °C.

[0005] Furthermore, the total charge during the converter smelting process is controlled at 125t~130t, and the scrap steel ratio is controlled at 15%~20%.

[0006] Furthermore, the oxygen supply intensity during the converter smelting process is 3.6~4.0 Nm. 3 / t / min, the oxygen flow rate remains constant during the smelting process.

[0007] Furthermore, during the converter smelting process, the distance between the oxygen lance position and the molten steel surface is controlled to be 1.9~2.0m.

[0008] Furthermore, the bottom-blown argon intensity during the converter smelting process is 0.08~0.2 Nm. 3 / t / min.

[0009] Furthermore, the final temperature of the converter smelting is controlled at 1620℃~1640℃, and the final carbon content is controlled at 0.04%~0.08%.

[0010] The working principle and beneficial effects of this invention are as follows: For converter smelting processes, the silicon content of the molten iron directly affects the oxygen supply and charging systems during smelting. Due to the combined use of molten iron ladles and the untimely delivery of desulfurized molten iron samples, inaccurate or missing silicon content occurs in the molten iron after the converter starts blowing, thus affecting converter smelting operations. Flue gas analysis technology can dynamically monitor the reactions within the converter during smelting; however, existing methods mainly focus on using flue gas data to predict the final composition of the converter, and no methods have yet been found to predict the silicon content of the molten iron entering the furnace and guide charging.

[0011] In this invention, in order to improve converter smelting operation, a method for predicting the silicon content of molten iron fed into the furnace using flue gas analysis data is proposed. By analyzing the variation law of flue gas composition during converter smelting under different silicon contents of molten iron fed into the furnace, a silicon content prediction model is established to guide the charging operation, thereby realizing precise operation of converter smelting and improving the dephosphorization effect and temperature control accuracy of the converter. Detailed Implementation

[0012] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0013] This invention is applicable to converter production processes equipped with flue gas analysis systems, and the specific process is as follows: (1) After the converter is filled with scrap steel and molten iron, and the furnace body is straightened, the oxygen lance is lowered to start blowing. During the blowing process, the nitrogen content and carbon dioxide content will gradually change. When the nitrogen content in the flue gas begins to decrease and the carbon dioxide content begins to rise synchronously, the carbon-oxygen reaction begins to occur in the furnace, and the carbon in the molten pool begins to be oxidized. Record the time and define this time as the start time of the flue gas analysis system t1, s. (2) Starting from time t1, record the CO content in the converter flue gas at 1-second intervals, and define it as W. iCO , % represents the CO content in the flue gas at time i, % (3) For this furnace, the first two minutes from t1, i.e., t1~t 120 The recorded CO volume content value W iCO The average CO content W was obtained by averaging. ACO And store the average value in the database; (4) Read the W value of this furnace from the data storage. ACO %,%; using the iron-silicon content prediction model W Si =-0.018W ACO +0.768 Calculate the mass content of silicon W in molten iron. Si ,%.

[0014] Furthermore, the total amount of lime added W during the converter smelting process 石灰 =2057 + 3500W Si , kg; Total amount of pellets added W 球团 =-14839+50.9HM_WGT+7.69 HM_TEP-53.9SCRAP_WGT+ 4116 W SiHM_WGT represents the weight of molten iron entering the furnace, in kg; SCRAP_WGT represents the weight of scrap steel, in t; HM_TEP represents the temperature of molten iron entering the furnace, in °C.

[0015] The total charge during the converter smelting process is controlled at 125t~130t, and the scrap steel ratio is controlled at 15%~20%.

[0016] The oxygen supply intensity during the converter smelting process is 3.6~4.0 Nm. 3 / t / min, the oxygen flow rate remains constant during the smelting process.

[0017] During the converter smelting process, the distance between the oxygen lance position and the molten steel surface should be controlled at 1.9~2.0m.

[0018] The bottom-blown argon intensity during the converter smelting process is 0.08~0.2 Nm. 3 / t / min.

[0019] The final temperature of the converter smelting is controlled at 1620℃~1640℃, and the mass content of carbon at the final point is controlled at 0.04%~0.08%.

[0020] Two embodiments of the present invention in specific applications are given below: Example

[0021] Example 1

[0022] Taking the applicant's 120t converter at the steel plant as an example, the converter is equipped with a flue gas analysis system during production. In this heat, after adding scrap steel and molten iron, the oxygen lance was lowered. The amount of molten iron added was 110t at a temperature of 1350℃, and the amount of scrap steel added was 20t. The blowing process adopted a constant pressure, variable lance position operation mode, with an oxygen flow rate of 27000 Nm³. 3 / h, bottom blowing flow rate is 600 Nm 3 / h, nitrogen blanketing flow rate is 5400 Nm 3 / h, the blow gun position is 2.0m, and the bottom-blown argon intensity is 0.1 Nm. 3 / t / min. When the blowing time t=20s, the nitrogen content in the flue gas begins to decrease and the carbon dioxide content increases. This is defined as the start time of the flue gas analysis system. Thereafter, the volumetric CO content in the flue gas is recorded every 1s, and the average CO content in the flue gas for the first two minutes is calculated to be 17.1%. W Si =-0.018W ACO +0.768, the mass content of silicon in the molten iron can be calculated to be 0.46% using the formula. From the formula W... 石灰 =2057 +3500W Si The calculated lime addition for this batch is 3667 kg; according to formula W... 球团=-14839+50.9HM_WGT+7.69 HM_TEP-53.9SCRAP_WGT+ 4116 W Si The calculated amount of pellets added to this furnace is 1878 kg. The final converter temperature is 1630℃, and the carbon content is 0.05%.

[0023] Example 2

[0024] Taking the applicant's 120t converter at the steel plant as an example, the converter is equipped with a flue gas analysis system during production. In this heat, after adding scrap steel and molten iron, the oxygen lance was lowered. The amount of molten iron added was 105t at a temperature of 1380℃, and the amount of scrap steel added was 25t. The blowing process adopted a constant pressure, variable lance position operation mode, with an oxygen flow rate of 27000 Nm³. 3 / h, bottom blowing flow rate is 600 Nm 3 / h, nitrogen blanketing flow rate is 5400 Nm 3 / h, the blow gun position is 1.9m, and the bottom-blown argon intensity is 0.15 Nm. 3 / t / min. When the blowing time t=18s, the nitrogen content in the flue gas begins to decrease and the carbon dioxide content increases. This is defined as the start time of the flue gas analysis system. Thereafter, the CO content in the flue gas is recorded every 1 second, and the average CO content in the flue gas for the first two minutes is calculated to be 13.8%. W Si =-0.018W ACO +0.768, the silicon content in the molten iron can be calculated to be 0.52% using the formula. (W...) 石灰 =2057 + 3500W Si The calculated lime addition for this batch is 3877 kg; according to formula W... 球团 =-14839+50.9HM_WGT+7.69 HM_TEP-53.9SCRAP_WGT+4116 W Si The calculated amount of pellets added to this furnace is 1910 kg. The final converter temperature is 1625℃, and the carbon content is 0.07%.

[0025] The technical means disclosed in this invention are not limited to those disclosed above, but also include technical solutions composed of any combination of the above technical features.

[0026] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for predicting silicon content in molten iron and controlling charging in a converter smelting process, applicable to converter production processes equipped with a flue gas analysis system, characterized in that... Includes the following steps: (1) After the converter is filled with scrap steel and molten iron, and the furnace body is straightened, the oxygen lance is lowered to start blowing. During the blowing process, the nitrogen content and carbon dioxide content will gradually change. When the nitrogen content in the flue gas begins to decrease and the carbon dioxide content begins to rise synchronously, the carbon-oxygen reaction begins to occur in the furnace, and the carbon in the molten pool begins to be oxidized. Record the time and define this time as the start time of the flue gas analysis system t1, s. (2) Starting from time t1, record the CO content in the converter flue gas at 1-second intervals, and define it as W. iCO , % represents the CO content in the flue gas at time i, % (3) For this furnace, the first two minutes from t1, i.e., t1~t 120 The recorded CO volume content value W iCO The average CO content W was obtained by averaging. ACO And store the average value in the database; (4) Read the W value of this furnace from the data storage. ACO %,%; using the iron-silicon content prediction model W Si =-0.018W ACO +0.768 Calculate the mass content of silicon W in molten iron. Si ,%.

2. The method according to claim 1, characterized in that, The total amount of lime added during the converter smelting process, W 石灰 =2057 + 3500W Si , kg; Total amount of pellets added W 球团 =-14839+50.9HM_WGT+7.69 HM_TEP-53.9SCRAP_WGT+ 4116 W Si HM_WGT represents the weight of molten iron entering the furnace, in kg; SCRAP_WGT represents the weight of scrap steel, in t; HM_TEP represents the temperature of molten iron entering the furnace, in °C.

3. The method according to claim 1, characterized in that, The total charge during the converter smelting process is controlled at 125t~130t, and the scrap steel ratio is controlled at 15%~20%.

4. The method according to claim 1, characterized in that, The oxygen supply intensity during the converter smelting process is 3.6~4.0 Nm. 3 / t / min, the oxygen flow rate remains constant during the smelting process.

5. The method according to claim 1, characterized in that, During the converter smelting process, the distance between the oxygen lance position and the molten steel surface is controlled to be 1.9~2.0m.

6. The method according to claim 1, characterized in that, The bottom-blown argon intensity during the converter smelting process is 0.08~0.2 Nm. 3 / t / min.

7. The method according to claim 1, characterized in that, The final temperature of the converter smelting is controlled at 1620℃~1640℃, and the mass content of carbon at the final point is controlled at 0.04%~0.08%.