A method for high-efficiency temperature raising of a converter
By adding high-carbon coke or semi-coke as a temperature-raising agent in batches during the converter steelmaking process, taking into account the time of low-temperature foamy slag overflow from the furnace mouth and the final carbon content, the problems of insignificant temperature-raising effect and high cost in converter steelmaking are solved, thus achieving efficient and low-cost converter steelmaking.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TANGSHAN DONGHUA IRON & STEEL ENTERPRISE GRP CO LTD
- Filing Date
- 2024-01-11
- Publication Date
- 2026-06-19
Abstract
Description
Technical Field
[0001] This invention relates to a method for efficient temperature raising in a converter, belonging to the technical field of converter steelmaking production processes in the metallurgical industry. Background Technology
[0002] When scrap steel prices fall below the cost of molten iron, steel companies compete to increase the scrap steel ratio in converters to reduce molten iron consumption. This reduction in molten iron consumption leads to a corresponding decrease in physical and chemical heat within the converter. To compensate for this reduced heat, various reheating methods are required. The most common reheating methods involve adding coal, coke, and composite silicon carbide balls to the furnace. However, improper addition methods result in insignificant temperature increases, further raising costs. Furthermore, excessive addition can introduce excessive sulfur, negatively impacting steel quality.
[0003] CN 115927782 A discloses a method for increasing the scrap ratio in a converter using hydrothermal char. This method involves adding hydrothermal char and scrap steel simultaneously. However, due to the high carbon content in the molten iron, the carbon in the molten pool is saturated in the early stages of blowing, resulting in the hydrothermal char burning primarily on the slag surface with low utilization. Furthermore, this method requires up to 30 kg of hydrothermal char per ton of steel, leading to high costs.
[0004] CN 115522011 A discloses a method for improving the thermal balance of converter smelting by adjusting the timing of coke addition as a converter temperature-raising agent. This method adds coke when the converter oxygen supply reaches 60%, but it does not specify the slag formation state inside the converter. If the slag is in a re-drying state, the coke will burn on the slag surface, failing to achieve the desired temperature-raising effect. Because this method does not consider the slag state, the amount of coke added is significantly limited, only 1.5-2.0 kg / ton of steel can be added, resulting in a small temperature increase. It also limits the amount of scrap steel that can be added, leading to limited cost reduction. Summary of the Invention
[0005] The purpose of this invention is to provide a method for efficient temperature raising in a converter. During the blowing process, the final temperature is determined by the overflow of low-temperature foamy slag and the final carbon content to determine whether the tapping temperature meets the requirements. In the later stages of blowing, the converter sonar slag-forming system is referenced, and a temperature-raising agent is added when the slag-forming is good, thereby solving the problems existing in the background technology.
[0006] The technical solution of this invention is:
[0007] A method for efficient temperature raising in a converter involves determining the final temperature of the converter based on the time of low-temperature foamy slag overflowing from the furnace mouth and the final carbon requirement during the blowing process. If the actual tapping temperature requirement is not met, a temperature-raising agent is added in batches after 8 minutes of converter blowing and when the sonar slag-forming audio index is in the range of 20%-30%. The amount of temperature-raising agent added at one time shall not exceed 2.0 kg / ton of steel until the actual tapping temperature requirement is met.
[0008] The principle for determining the converter's endpoint temperature based on the time of low-temperature foamy slag overflow from the furnace mouth and the endpoint carbon requirement is as follows: Calculated based on low-temperature foamy slag overflowing from the furnace mouth after 6 minutes of blowing, endpoint carbon of 0.07%, and endpoint temperature of 1620℃±10℃, for every 0.01% decrease or increase in endpoint carbon, the endpoint temperature increases or decreases by 10℃; for every 1 minute earlier or later the time of low-temperature foamy slag overflowing from the furnace mouth, the endpoint temperature increases or decreases by 10℃.
[0009] The total cumulative amount of the temperature-raising agent added shall not exceed 6 kg / ton of steel.
[0010] The temperature-raising agent refers to coke or semi-coke with a carbon content of ≥80% and a particle size of 10-40mm.
[0011] The heating effect is considered based on adding 1.0 kg / ton of heating agent to raise the temperature by 10℃-12℃.
[0012] After each addition of the heating agent, the oxygen lance position is raised by 100-200mm to slag, and the oxygen lance position is restored after 5-15 seconds of blowing.
[0013] The converter charging system is designed for a hot metal consumption of ≤860kg / t, a hot metal temperature of ≥1250℃, a converter oxygen supply time of 11-13 minutes, and a converter tapping temperature of 1600℃-1700℃.
[0014] The low-temperature foam slag refers to the dark red, foamy converter slag.
[0015] The beneficial effects of this invention are: the blowing process determines whether the final temperature meets the tapping temperature requirements by measuring the overflow low-temperature foam slag time and the final carbon content; and in the middle and later stages of blowing, the converter sonar slag-forming system is referenced, and a temperature-raising agent is added when the slag-forming is in good condition to improve the temperature-raising effect and reduce smelting costs. Detailed Implementation
[0016] A method for efficient temperature raising in a converter involves determining the final temperature of the converter based on the time of low-temperature foamy slag overflowing from the furnace mouth and the final carbon requirement during the blowing process. If the actual tapping temperature requirement is not met, a temperature-raising agent is added in batches after 8 minutes of converter blowing and when the sonar slag-forming audio index is in the range of 20%-30%. The amount of temperature-raising agent added at one time shall not exceed 2.0 kg / ton of steel until the actual tapping temperature requirement is met.
[0017] The principle for determining the converter's endpoint temperature based on the time of low-temperature foamy slag overflow from the furnace mouth and the endpoint carbon requirement is as follows: Calculated based on low-temperature foamy slag overflowing from the furnace mouth after 6 minutes of blowing, endpoint carbon of 0.07%, and endpoint temperature of 1620℃±10℃, for every 0.01% decrease or increase in endpoint carbon, the endpoint temperature increases or decreases by 10℃; for every 1 minute earlier or later the time of low-temperature foamy slag overflowing from the furnace mouth, the endpoint temperature increases or decreases by 10℃.
[0018] In this embodiment, control is specifically performed according to the following requirements:
[0019] a. The converter charging system is organized according to the following conditions: hot iron consumption ≤860kg / t, hot iron temperature ≥1250℃, oxygen supply time in converter 11-13 minutes, and steel tapping temperature in converter 1600℃-1700℃.
[0020] b. Determine the converter's final temperature based on the time of low-temperature foamy slag overflowing from the furnace mouth and the final carbon requirement, and determine whether a temperature increase is necessary based on the actual tapping temperature requirement; the low-temperature foamy slag refers to dark red, foamy converter slag.
[0021] c. If a temperature increase is required, refer to the sonar slag analysis after 8 minutes of converter blowing. When the sonar slag audio index is in the range of 20%-30%, add a temperature-raising agent. The temperature-raising agent refers to coke, semi-coke, etc. with a carbon content ≥80% and a particle size of 10-40mm.
[0022] d. If, after adding the heating agent under good slag-forming conditions, the CO produced by the carbon-oxygen reaction in the furnace is discharged and obvious slag formation occurs at the converter mouth, then the heating is considered effective. The heating effect is considered based on adding 1.0 kg / ton of heating agent to raise the temperature by 10℃-12℃, and the amount of heating agent added at one time shall not exceed 2.0 kg / ton of steel.
[0023] e. After adding the first batch of heating agent, raise the oxygen lance position by 100-200mm to slag. After blowing for 5-15 seconds, when the audio index is 20%-30%, restore the oxygen lance position. Add the second batch of heating agent according to the required tapping temperature. This method can be used to add heating agent multiple times. The total amount of heating agent added multiple times should not exceed 6kg / ton of steel. Example 1
[0024] An 80-ton converter consumes 800 kg of molten iron per ton of steel. The required tapping temperature for the smelted steel is 1600℃±10℃, and the final carbon content is ≥0.090%. After 5 minutes of blowing, low-temperature foamy slag overflows from the furnace mouth, indicating the final temperature should be 1610℃±10℃. If the slag removal time is advanced by 1 minute, the final temperature should be increased by 10℃. If the final carbon content is increased by 0.02%, the final temperature should be decreased by 20℃. The calculated final temperature is 1620 + 10 - 20 = 1610℃, so no temperature increase is needed. After 11 minutes and 27 seconds of blowing, carbon is removed, and the measured furnace temperature is 1606℃, with a final carbon content of 0.092%. Example 2
[0025] A 150-ton converter consumes 790 kg of molten iron per ton of steel. The required tapping temperature for the smelted steel is 1640℃±10℃, and the final carbon requirement is ≤0.050%. After 8 minutes of blowing, low-temperature foamy slag overflows from the furnace mouth, indicating the final temperature should be 1620℃±10℃. Delaying the slag removal time by 2 minutes reduces the final temperature by 20℃. Reducing the final carbon requirement by 0.02% increases the final temperature by 20℃. The calculated final temperature is 1620 - 20 + 20 = 1620℃, requiring a 20℃ increase. After 9 minutes and 35 seconds of blowing, the sonar slag-forming audio index is 25%. The first batch of 300 kg of coke (81% carbon content, 25-40mm particle size) is added. Immediate slag removal at the furnace mouth after addition is observed, indicating effectiveness. After 12 minutes and 51 seconds of blowing, carbon is removed, and the furnace temperature is measured at 1637℃, with a final carbon content of 0.047%. Example 3
[0026] A 120-ton converter consumes 820 kg of molten iron per ton of steel. The required tapping temperature for the smelted steel grade is 1660℃±10℃, and the final carbon content must be ≥0.070%. After 6 minutes of blowing, low-temperature foamy slag overflows from the furnace mouth, indicating the final temperature should be 1620℃±10℃, requiring a 40℃ temperature increase. At 8 minutes and 20 seconds of blowing, the sonar slag-forming audio index is 23%. The first batch of 240 kg of semi-coke (84% carbon content, 10-25mm particle size) is added; slag immediately rises from the furnace mouth after addition, indicating effectiveness. At 8 minutes and 55 seconds of blowing, the lance is raised 100mm; 10 seconds later, the sonar slag-forming audio index is 28%, and the lance is returned to its original position. The second batch of 240 kg of semi-coke is added; slag immediately rises from the furnace mouth after addition, indicating effectiveness. At 12 minutes and 33 seconds of blowing, carbon is extracted, and the furnace temperature is measured at 1662℃, with a final carbon content of 0.073%.
Claims
1. A method for high efficiency temperature ramping in a converter, characterized by: During the blowing process, the converter endpoint temperature is determined based on the time of low-temperature foamy slag overflow from the furnace mouth and the endpoint carbon requirement. If the actual tapping temperature requirement is not met, the temperature-raising agent is added in batches after 8 minutes of blowing in the converter and when the sonar slag audio index is in the range of 20%-30%. The amount of temperature-raising agent added at one time shall not exceed 2.0 kg / ton of steel until the actual tapping temperature requirement is met. The principle for determining the converter's endpoint temperature based on the time of low-temperature foamy slag overflow from the furnace mouth and the endpoint carbon requirement is as follows: Calculated based on low-temperature foamy slag overflowing from the furnace mouth after 6 minutes of blowing, endpoint carbon of 0.07%, and endpoint temperature of 1620℃±10℃, for every 0.01% decrease or increase in endpoint carbon, the endpoint temperature increases or decreases by 10℃; for every 1 minute earlier or later the time of low-temperature foamy slag overflowing from the furnace mouth, the endpoint temperature increases or decreases by 10℃.
2. The method of claim 1, wherein: The total cumulative amount of the temperature-raising agent added shall not exceed 6 kg / ton of steel.
3. The method for high efficiency temperature raising of a converter according to claim 1 or 2, characterized in that: The temperature-raising agent refers to coke or semi-coke with a carbon content of ≥80% and a particle size of 10-40mm.
4. The method of claim 1, wherein: The heating effect is considered based on adding 1.0 kg / ton of heating agent to raise the temperature by 10℃-12℃.
5. The method of claim 1, wherein: After each addition of the heating agent, the oxygen lance position is raised by 100-200mm to slag, and the oxygen lance position is restored after 5-15 seconds of blowing.
6. The method for efficient temperature raising of a converter according to claim 1, characterized in that: The converter charging system is designed for a hot metal consumption of ≤860kg / t, a hot metal temperature of ≥1250℃, a converter oxygen supply time of 11-13 minutes, and a converter tapping temperature of 1600℃-1700℃.
7. The method for efficient temperature raising of a converter according to claim 1, characterized in that: The low-temperature foam slag refers to the dark red, foamy converter slag.