CN108998733B - LF furnace top slag modification method of conductive steel - Google Patents
LF furnace top slag modification method of conductive steel Download PDFInfo
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- CN108998733B CN108998733B CN201810898686.9A CN201810898686A CN108998733B CN 108998733 B CN108998733 B CN 108998733B CN 201810898686 A CN201810898686 A CN 201810898686A CN 108998733 B CN108998733 B CN 108998733B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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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
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
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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
- C21C7/06—Deoxidising, e.g. killing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
Abstract
The invention relates to a modification method of LF furnace top slag of conductive steel, wherein the conductive steel adopts an external refining process of an LF furnace and a VD furnace, the LF furnace refining process is divided into the following 3 steps, namely, the step 1: heating to melt slag; step 2: stopping heating, adding an aluminum wire section according to the oxygen content of the molten steel to perform molten steel deoxidation operation, and controlling the oxygen content in the molten steel to be 0.01-0.02% after smelting; and step 3: adding lime, fluorite and top slag modifier to adjust top slag, ensuring the content of FeO in the top slag to be 3-5%, and ensuring the oxygen content balance of the top slag and molten steel at the moment without mutual oxygen transmission; the method not only controls the oxygen content in the molten steel, but also controls the oxygen content in the molten steel top slag and the oxygen content in the tundish slag, ensures that the oxygen content of the molten steel and the top slag are both in a reasonable range, and further ensures smooth running of the molten steel during continuous casting and pouring.
Description
Technical Field
The invention relates to the technical field of steel making, in particular to a modification method of LF furnace top slag of conductive steel.
Background
The chemical composition of the conductive steel for producing the conductive steel wire, the conductive steel sheet or the conductive steel bar is similar to that of industrial pure iron, and in the production process, aluminum particles are generally adopted as deoxidizing agents in a steel-making process and a refining process, and the aluminum particles react with oxygen in molten steel to generate Al2O3The problem of flocculation during continuous casting and pouring is caused by inclusion, which becomes a main problem in the production of the steel of the variety.
The main flocculated flow is Al through the analysis of the flocculated flow product2O3The main reasons for this are two kinds: firstly, Al generated in the smelting process of molten steel2O3Non-metallic inclusions with high melting points cannot float upwards in molten steel and are adhered to the inner wall of a water gap to form nodules; secondly, Al generated by secondary oxidation of molten steel2O3And high-melting-point inclusions are adhered to the inner wall of the water gap to form nodules.
Disclosure of Invention
The invention provides a modification method of LF furnace top slag of conductive steel, which is characterized in that besides controlling the oxygen content in molten steel, the oxygen content in molten steel top slag and the oxygen content in tundish slag are also controlled in a key way, so that the oxygen contents of the molten steel and the top slag are ensured to be in a reasonable range, and further, the smooth running of the molten steel during continuous casting and pouring is ensured.
In order to achieve the purpose, the invention adopts the following technical scheme:
the LF furnace top slag modification method of the conductive steel comprises the following chemical components in percentage by mass: c is less than or equal to 0.010 percent; si is less than or equal to 0.010 percent; mn is less than or equal to 0.06 percent; p is less than or equal to 0.015 percent; s is less than or equal to 0.010 percent; n is less than or equal to 0.0040 percent; the balance of iron and inevitable impurities;
the conductive steel adopts an external refining process of an LF furnace and a VD furnace, wherein the refining process of the LF furnace comprises the following 3 steps:
step 1: heating to melt slag; adding 3.5-4.5 kg of lime per ton of steel and 0.8-1.2 kg of fluorite per ton of steel, heating for more than 10 minutes by using an electrode, and simultaneously adjusting the flow of argon to be 150-200 NL/min to melt top slag;
step 2: stopping heating, adjusting the flow of argon gas to 200-250 NL/min, simultaneously adding 1.3-1.5 kg/ton steel and aluminum wire section, stirring for 3-5 minutes, and measuring the oxygen value of molten steel by using an oxygen determination instrument; continuously adding an aluminum wire section to perform molten steel deoxidation operation according to the oxygen content of the molten steel, and controlling the oxygen content in the molten steel to be 0.01-0.02% after smelting is finished;
and step 3: adding white ash, fluorite and top slag modifier to adjust top slag, wherein the adding amount of the fluorite is 0.7-1.3 kg per ton of steel, the adding amount of the white ash is 3-4 times of that of the fluorite, and the top slag modifier is added according to 1.3-1.7 kg per ton of steel; adjusting the flow of argon gas to be 150-200 NL/min, stirring weakly for 3-5 minutes, sampling and testing to ensure that the content of FeO in the top slag is 3% -5%, and at the moment, ensuring the oxygen content balance of the top slag and the molten steel without mutual oxygen transfer; and (4) heating the electrode to raise the temperature, finishing the smelting process of the LF furnace after the tapping temperature is reached, and transferring the molten steel to a VD furnace for next vacuum smelting.
The top slag modifier is aluminum slag ball.
Compared with the prior art, the invention has the beneficial effects that:
the method of the invention basically eliminates the problem of large content of non-metal inclusions in steel when the square billet is used for producing the conductive steel, obviously improves the castability of the molten steel when the steel is produced, greatly improves the surface quality of the casting blank, and does not have the conditions of speed reduction, casting interruption and the like.
Detailed Description
The invention relates to a modification method of LF furnace top slag of conductive steel, which comprises the following chemical components in percentage by mass: c is less than or equal to 0.010 percent; si is less than or equal to 0.010 percent; mn is less than or equal to 0.06 percent; p is less than or equal to 0.015 percent; s is less than or equal to 0.010 percent; n is less than or equal to 0.0040 percent; the balance of iron and inevitable impurities;
the conductive steel adopts an external refining process of an LF furnace and a VD furnace, wherein the refining process of the LF furnace comprises the following 3 steps:
step 1: heating to melt slag; adding 3.5-4.5 kg of lime per ton of steel and 0.8-1.2 kg of fluorite per ton of steel, heating for more than 10 minutes by using an electrode, and simultaneously adjusting the flow of argon to be 150-200 NL/min to melt top slag;
step 2: stopping heating, adjusting the flow of argon gas to 200-250 NL/min, simultaneously adding 1.3-1.5 kg/ton steel and aluminum wire section, stirring for 3-5 minutes, and measuring the oxygen value of molten steel by using an oxygen determination instrument; continuously adding an aluminum wire section to perform molten steel deoxidation operation according to the oxygen content of the molten steel, and controlling the oxygen content in the molten steel to be 0.01-0.02% after smelting is finished;
and step 3: adding white ash, fluorite and top slag modifier to adjust top slag, wherein the adding amount of the fluorite is 0.7-1.3 kg per ton of steel, the adding amount of the white ash is 3-4 times of that of the fluorite, and the top slag modifier is added according to 1.3-1.7 kg per ton of steel; adjusting the flow of argon gas to be 150-200 NL/min, stirring weakly for 3-5 minutes, sampling and testing to ensure that the content of FeO in the top slag is 3% -5%, and at the moment, ensuring the oxygen content balance of the top slag and the molten steel without mutual oxygen transfer; and (4) heating the electrode to raise the temperature, finishing the smelting process of the LF furnace after the tapping temperature is reached, and transferring the molten steel to a VD furnace for next vacuum smelting.
The top slag modifier is aluminum slag ball.
In the smelting process of the conventional steel grade, the oxygen content in molten steel is usually controlled, but the conductive steel is a special steel grade, is limited by the characteristics of the molten steel, and the molten steel needs to keep a certain oxygen content (0.002% -0.004%) during continuous casting, so that in the process of an LF refining furnace, the oxygen content in the molten steel is reasonably controlled, and the oxygen content in top slag is reasonably controlled.
Because the oxygen content of the molten steel is higher in the smelting process, the top slag also contains higher oxygen content before the top slag is not modified, and the oxygen content in the molten steel cannot be controlled because the top slag transfers oxygen to the molten steel in the subsequent smelting and continuous casting pouring processes of the molten steel, so that the top slag reacts with residual aluminum in the molten steel to form floc Al2O3Ultimately resulting in a wadding flow during continuous casting. For the reasons, the top slag is modified in the LF refining furnace.
In the top slag modification process, argon control is matched, namely the flow of argon is properly controlled to be medium and small flow at the stage of electrifying, heating and melting the top slag, and the specific flow is 150-200 NL/min; after slagging, adjusting argon to medium strength, and adding an aluminum wire segment to deoxidize molten steel, wherein the specific flow is 200-250 NL/min; in the top slag modification stage, the argon is reduced, the specific flow is 150-200 NL/min, and the floating of inclusions is promoted while the top slag modification effect is ensured.
The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.
[ examples ] A method for producing a compound
When the conductive steel is produced, the weight of the molten steel in the tank is 100 tons; the refining process of the LF furnace is divided into three stages: in the first stage, the temperature is raised to melt slag, 400kg of lime and 100kg of fluorite are added, and the electrodes are electrified and heated for 10 minutes; simultaneously, the flow rate of argon is adjusted to 180NL/min to melt the top slag; stopping heating at the second stage, adjusting argon to 250NL/min, simultaneously adding 147kg of aluminum wire segments, stirring for 3 minutes, and measuring the oxygen value of the molten steel to be 0.018% by using an oxygen determination instrument when the color of the top slag is observed to be black; in the third stage, 280kg of lime, 70kg of fluorite and 150kg of top slag modifier are added to adjust top slag, the flow rate of argon is adjusted to 170NL/min, weak stirring is carried out for 3 minutes, sampling and testing are carried out on the top slag when the color of the top slag is observed to be black and gray, and the testing result shows that the content of FeO in the top slag is 4.3%; heating for 10 minutes by an electrode according to the temperature condition of the molten steel to enable the temperature of the molten steel to reach the tapping temperature, finishing the smelting process of the LF furnace, and transferring the molten steel to a VD furnace for the next vacuum smelting.
The whole pouring process of the conductive steel after the external refining process is very smooth during continuous casting; after multiple times of implementation, the problem of flocculation is not generated, and the technical scheme of the invention is feasible and can be applied to the process of producing the conductive steel by using the square billet.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (1)
1. The LF furnace top slag modification method of the conductive steel is characterized in that the conductive steel comprises the following chemical components in percentage by mass: c is less than or equal to 0.010 percent; si is less than or equal to 0.010 percent; mn is less than or equal to 0.06 percent; p is less than or equal to 0.015 percent; s is less than or equal to 0.010 percent; n is less than or equal to 0.0040 percent; the balance of iron and inevitable impurities;
the conductive steel adopts an external refining process of an LF furnace and a VD furnace, wherein the refining process of the LF furnace comprises the following 3 steps:
step 1: heating to melt slag; adding 3.5-4.5 kg of lime per ton of steel and 0.8-1.2 kg of fluorite per ton of steel, heating for more than 10 minutes by using an electrode, and simultaneously adjusting the flow of argon to be 150-200 NL/min to melt top slag;
step 2: stopping heating, adjusting the flow of argon gas to 200-250 NL/min, simultaneously adding 1.3-1.5 kg/ton steel and aluminum wire section, stirring for 3-5 minutes, and measuring the oxygen value of molten steel by using an oxygen determination instrument; continuously adding an aluminum wire section to perform molten steel deoxidation operation according to the oxygen content of the molten steel, and controlling the oxygen content in the molten steel to be 0.01-0.02% after smelting is finished;
and step 3: adding lime, fluorite and top slag modifier to adjust top slag, wherein the top slag modifier is aluminum slag balls; the adding amount of fluorite is 0.7-1.3 kg per ton of steel, the adding amount of white ash is 3-4 times of that of fluorite, and the top slag modifier is added according to 1.3-1.7 kg per ton of steel; adjusting the flow of argon gas to be 150-200 NL/min, stirring weakly for 3-5 minutes, sampling and testing to ensure that the content of FeO in the top slag is 3% -5%, and at the moment, ensuring the oxygen content balance of the top slag and the molten steel without mutual oxygen transfer; and (4) heating the electrode to raise the temperature, finishing the smelting process of the LF furnace after the tapping temperature is reached, and transferring the molten steel to a VD furnace for next vacuum smelting.
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| CN201810898686.9A CN108998733B (en) | 2018-08-08 | 2018-08-08 | LF furnace top slag modification method of conductive steel |
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| CN201810898686.9A CN108998733B (en) | 2018-08-08 | 2018-08-08 | LF furnace top slag modification method of conductive steel |
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| CN108998733B true CN108998733B (en) | 2020-06-23 |
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| CN111505235B (en) * | 2020-04-30 | 2022-04-15 | 辽宁科技大学 | Method for measuring interface oxygen transfer rate in process of smelting high-temperature alloy |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107794345A (en) * | 2016-09-06 | 2018-03-13 | 鞍钢股份有限公司 | A kind of LF stoves produce the secondary slag practice of low silicon aluminium killed steel |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107794345A (en) * | 2016-09-06 | 2018-03-13 | 鞍钢股份有限公司 | A kind of LF stoves produce the secondary slag practice of low silicon aluminium killed steel |
Non-Patent Citations (1)
| Title |
|---|
| 连铸水口堵塞、絮流原因分析及预防措施;苏小利等;《第十届中国钢铁年会暨第六届宝钢学术年会论文集》;冶金工业出版社;20151031;3.3 减少水口絮流措施 * |
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