CN116179798A - Method for reducing nitrogen content in ultra-low carbon IF steel - Google Patents
Method for reducing nitrogen content in ultra-low carbon IF steel Download PDFInfo
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- CN116179798A CN116179798A CN202111417654.0A CN202111417654A CN116179798A CN 116179798 A CN116179798 A CN 116179798A CN 202111417654 A CN202111417654 A CN 202111417654A CN 116179798 A CN116179798 A CN 116179798A
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- steel
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention relates to the field of refining technology of metal smelting, in particular to a method for reducing nitrogen content in ultralow-carbon IF steel. According to the method, through a process of blowing carbon dioxide and argon gas from the bottom of the steel ladle in the tapping process of smelting the ultra-low carbon IF steel by the converter, the number of bubbles in the steel is increased by utilizing the characteristic that the carbon dioxide is larger than the air in specific gravity and the reaction of the carbon dioxide and carbon in the steel liquid, so that the protection effect of preventing the oxidation and nitrogen increase of the steel liquid and the denitrification effect of enhancing the gas in the steel liquid in the tapping process are realized, and the nitrogen increase of the steel liquid and the nitrogen content in the steel liquid in the tapping process are effectively reduced. The invention is beneficial to reducing the load of IF molten steel vacuum denitrification and the adding amount of titanium alloy, and effectively reduces the vacuum treatment time and the alloy cost.
Description
Technical Field
The invention belongs to the field of refining technology of metal smelting, and particularly relates to a method for reducing nitrogen content in ultralow-carbon IF steel.
Background
The ultra-low carbon IF steel is a steel for automobiles with no gap atoms for deep filling, is widely applied in the automobile industry, reduces the content of carbon and nitrogen elements in the steel as much as possible in the refining process, adopts titanium alloying to form carbon and titanium nitride so as to fix the carbon and nitrogen elements, and improves the ductility, formability and other deep drawing processing performances of the IF steel. In actual production, the carbon content can be reduced to the greatest extent by adopting vacuum treatment, but in the tapping process, the nitrogen absorption is serious due to unavoidable exposure of molten steel, the vacuum treatment time is long, the content of titanium alloying elements is improved, and the cost of vacuum treatment and alloy consumption is increased.
In order to reduce the nitrogen content in the IF steel, methods of optimizing converter end point control, reducing point blowing nitrogen increase, reducing nitrogen content in smelting raw materials, improving RH vacuum argon blowing circulation flow and the like are mainly adopted, but a method for controlling nitrogen absorption and nitrogen increase of molten steel in the tapping process is not very good, larger bubbles are easily formed by bottom argon blowing stirring, the number of the bubbles is small, the denitrification capability is limited, and the serious nitrogen absorption of molten steel is caused by serious molten steel rising in a ladle.
Disclosure of Invention
The invention aims to provide a low-cost and easy-to-operate method for reducing the nitrogen content in IF steel by fully utilizing carbon dioxide tail gas (or carbon dioxide gas from other sources) of a lime kiln matched with a steel plant for refining and degassing molten steel, and by utilizing the protection effect of carbon dioxide on molten steel in the tapping process and the bubble proliferation mechanism of 2 times of small bubbles generated by the reaction of carbon dioxide and carbon in steel, the effect of floating bubbles to remove nitrogen is effectively promoted, and the low-cost production of low-nitrogen steel is realized.
In order to achieve the above object, the present invention adopts the technical scheme as follows.
In the tapping process of smelting ultra-low carbon IF steel by a converter, a process of blowing carbon dioxide and argon gas from the bottom of a ladle is adopted, and the number of bubbles in the steel is increased by utilizing the characteristic that the carbon dioxide has a larger specific gravity than air and the reaction of the carbon dioxide and carbon in the steel liquid, so that the protection effect of preventing the oxidation and the nitrogen increase of the steel liquid and the nitrogen removal effect of gas in the steel liquid in the tapping process are realized, and the nitrogen increase amount of the steel liquid and the nitrogen content in the steel liquid in the tapping process are effectively reduced.
The bottom blowing gas is provided with two gas sources of carbon dioxide and argon, and the bottom blowing gas control equipment can realize independent control of the flow of the two gases and blow the two gases into the steel ladle through the air brick at the bottom of the steel ladle.
The carbon dioxide gas can be conveyed to a ladle bottom blowing system by adopting a recovery, purification and storage of carbon dioxide tail gas of a lime kiln which is matched with a steel mill and a corresponding gas supply system, or can be conveyed to the ladle bottom blowing system by adopting liquid carbon dioxide sold in the market through gasification and pressurization.
The carbon dioxide gas is blown at the bottom before tapping to drive the air in the ladle, and the process operation is as follows: 2-3 minutes before tapping of the converter, opening a ladle bottom blowing system to blow carbon dioxide gas to drive air in the ladle, avoiding the exposed oxidation and nitrogen absorption of molten steel in the ladle, and calculating the flow of the bottom blowing carbon dioxide gas according to the volume capacity of the ladle filled with the carbon dioxide gas for 2 minutes.
The ladle bottom blowing carbon dioxide and argon gas process comprises the following steps: in the tapping process, the tapping molten steel amount is within 1/3, all bottom blowing carbon dioxide gas is performed, and the ratio of the gas flow is 1/2 of the normal bottom blowing argon flow; the steel tapping amount is within 1/3-2/3, two mixed gases of carbon dioxide and argon are blown at the bottom, the ratio of the argon flow is 1/2 of the normal bottom blowing argon flow, and the carbon dioxide flow is 1/4 of the normal bottom blowing argon flow; the steel tapping amount is within 2/3-1, argon is blown out from the bottom, and the flow is the normal bottom argon blowing flow.
The normal bottom argon blowing flow is the flow when the ladle with different capacities adopts the bottom argon blowing process.
Claims (6)
1. A method for reducing nitrogen content in ultra-low carbon IF steel is characterized in that: in the tapping process of smelting ultra-low carbon IF steel by a converter, a process of blowing carbon dioxide and argon gas from the bottom of a ladle is adopted, and the number of bubbles in the steel is increased by utilizing the characteristic that the carbon dioxide is larger than the air in specific gravity and the reaction of the carbon dioxide and carbon in the steel liquid, so that the protection effect of preventing the oxidation and nitrogen increase of the steel liquid and the denitrification effect of enhancing the gas in the steel liquid in the tapping process are realized, and the nitrogen increase of the steel liquid and the nitrogen content in the steel liquid in the tapping process are effectively reduced.
2. The method for reducing nitrogen content in ultra-low carbon IF steel according to claim 1, wherein: the bottom blowing gas is provided with two furnace gas sources of carbon dioxide and argon, and the bottom blowing gas control equipment can realize the independent control of the flow of the two gases and blow the two gases into the ladle through the air brick at the bottom of the ladle.
3. The method for reducing nitrogen content in ultra-low carbon IF steel according to claim 1, wherein: the carbon dioxide gas can be conveyed to a ladle bottom blowing system by adopting a carbon dioxide tail gas recovery, purification and storage and corresponding gas supply system of a lime kiln which is matched with a steel mill, and can also be conveyed to the ladle bottom blowing system by adopting liquid carbon dioxide sold in the market through gasification and pressurization.
4. The method for reducing nitrogen content in ultra-low carbon IF steel according to claim 1, wherein: 2-3 minutes before tapping of the converter, opening a ladle bottom blowing system to blow carbon dioxide gas to drive air in the ladle, avoiding the exposed oxidation and nitrogen absorption of molten steel in the ladle, and calculating the flow of the bottom blowing carbon dioxide gas according to the volume capacity of the ladle filled with the carbon dioxide gas for 2 minutes.
5. The method for reducing nitrogen content in ultra-low carbon IF steel according to claim 1, wherein: in the tapping process, the tapping molten steel amount is within 1/3, all bottom blowing carbon dioxide gas is performed, and the ratio of the gas flow is 1/2 of the normal bottom blowing argon flow; the steel tapping amount is within 1/3-2/3, two mixed gases of carbon dioxide and argon are blown at the bottom, the ratio of the argon flow is 1/2 of the normal bottom blowing argon flow, and the carbon dioxide flow is 1/4 of the normal bottom blowing argon flow; the steel tapping amount is within 2/3-1, argon is blown out from the bottom, and the flow is the normal bottom argon blowing flow.
6. The method can be applied to the steel ladle bottom blowing process for tapping similar steel types of boiling tapping.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111417654.0A CN116179798A (en) | 2021-11-26 | 2021-11-26 | Method for reducing nitrogen content in ultra-low carbon IF steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111417654.0A CN116179798A (en) | 2021-11-26 | 2021-11-26 | Method for reducing nitrogen content in ultra-low carbon IF steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116179798A true CN116179798A (en) | 2023-05-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111417654.0A Pending CN116179798A (en) | 2021-11-26 | 2021-11-26 | Method for reducing nitrogen content in ultra-low carbon IF steel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116179798A (en) |
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2021
- 2021-11-26 CN CN202111417654.0A patent/CN116179798A/en active Pending
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