CN114941053A - Method for inhibiting resulfurization of molten steel tank by flushing acidic slag - Google Patents
Method for inhibiting resulfurization of molten steel tank by flushing acidic slag Download PDFInfo
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- CN114941053A CN114941053A CN202210555426.8A CN202210555426A CN114941053A CN 114941053 A CN114941053 A CN 114941053A CN 202210555426 A CN202210555426 A CN 202210555426A CN 114941053 A CN114941053 A CN 114941053A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 222
- 239000010959 steel Substances 0.000 title claims abstract description 222
- 239000002893 slag Substances 0.000 title claims abstract description 93
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000011010 flushing procedure Methods 0.000 title claims abstract description 18
- 230000002401 inhibitory effect Effects 0.000 title claims abstract description 11
- 230000002378 acidificating effect Effects 0.000 title description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 80
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 66
- 239000011593 sulfur Substances 0.000 claims abstract description 66
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 64
- 238000005406 washing Methods 0.000 claims abstract description 49
- 238000010438 heat treatment Methods 0.000 claims abstract description 45
- 229910052742 iron Inorganic materials 0.000 claims abstract description 40
- 238000007670 refining Methods 0.000 claims abstract description 35
- 239000002253 acid Substances 0.000 claims abstract description 34
- 239000000956 alloy Substances 0.000 claims abstract description 15
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 15
- 238000010079 rubber tapping Methods 0.000 claims abstract description 15
- 238000005266 casting Methods 0.000 claims abstract description 12
- 239000006004 Quartz sand Substances 0.000 claims abstract description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 60
- 229910052786 argon Inorganic materials 0.000 claims description 30
- 239000002436 steel type Substances 0.000 claims description 26
- 238000007664 blowing Methods 0.000 claims description 17
- 239000000428 dust Substances 0.000 claims description 14
- 230000008018 melting Effects 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 230000000630 rising effect Effects 0.000 claims description 2
- 238000004140 cleaning Methods 0.000 abstract description 7
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 239000011572 manganese Substances 0.000 description 9
- 229910052748 manganese Inorganic materials 0.000 description 6
- 238000003723 Smelting Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 206010039509 Scab Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010622 cold drawing Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- 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
-
- 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
- C21C7/076—Use of slags or fluxes as treating agents
-
- 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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a method for inhibiting resulfurization of a molten steel tank by flushing an acid slag tank, which comprises the following steps: s1, selecting steel with the component standard S not more than 0.045% as a tank washing steel, adding molten iron and common scrap steel into a converter for converting, wherein the molten iron meets the condition that S is not more than 0.03% when entering the converter, controlling the sulfur content of tapping of the converter, and tapping into a molten steel tank; s2, heating the molten steel tank in a refining LF furnace; s3, adjusting the alloy content, adding 2.5-4 kg of quartz sand into each ton of molten steel to make acid slag, and controlling the alkalinity of the slag to be less than 1.0; and S4, casting the molten steel and turning the ladle in time, and immediately cleaning slag on the wall and slag on the edge of the molten steel ladle after the ladle is turned, so that the treated molten steel ladle can be used for producing the ultra-low sulfur steel. The invention controls the alkalinity of the molten slag to be less than 1.0 by the acid slag process, can reduce the sulfur content in the slag, has good fluidity of the acid slag, has less residue adhesion on the wall and the bottom of the tank after casting, and can effectively inhibit the resulfurization of the molten steel tank during the production of the ultra-low sulfur steel.
Description
Technical Field
The invention relates to steel smelting, in particular to a method for reducing resulfurization of a molten steel tank in ultralow-sulfur steel smelting by using acid slag flushing.
Background
The cable steel wire rod is one of the main raw materials for producing the copper-clad steel, is widely applied to the fields of communication, electronics, transportation, rubber products and the like, has wide market prospect and has higher economic benefit. The drawing performance and the electric conductivity are key indexes for measuring the quality of the cable steel wire rod, the former requires that the surface of the wire rod has no defects such as scabs, folding, lugs and the like, and the drawing performance is good, so that the cold drawing processing of a user is smooth; the latter affects the manufacturing cost of copper clad steel wire manufacturing users and the performance of terminal products. Too low omega (Mn)/omega (S) in the steel can cause the billet to generate hot brittle rolling defects in the heating rolling process, the drawing performance is influenced, meanwhile, the increase of the manganese content in the steel can cause the electric conductivity to be reduced, so that the cable steel has to control the sulfur content to be extremely low (less than or equal to 0.007%).
The cable steel produced by limited steel-making of Wu steel adopts magnesium-based blowing and slag-removing processes, sulfur in molten iron entering a furnace can be controlled to be at an extremely low level (less than or equal to 0.001%), but residues attached to the wall and the bottom of a molten steel tank can easily enter the steel to cause molten steel resulfurization in the process of converter tapping and refining, and the sulfur in the steel exceeds the standard, so that the tank needs to be flushed before the cable steel is produced.
One limited steel-making smelting variety of Wu steel is an alkaline slag process, the alkalinity of molten slag is more than 2.0, the sulfur content in the molten slag reaches 1.0-2.0%, the molten iron is required to be controlled to enter the furnace sulfur with extremely low level by adopting alkaline slag flushing, low-sulfur waste steel is used, the molten iron is high in desulfurization and slagging cost in the molten iron tank, the molten iron is attached to the wall of the molten steel tank after the molten steel is cast, and the residues at the bottom of the molten steel tank cannot be thoroughly treated, so that the resulfurization is serious when the molten steel tank is put into the production of cable steel.
Therefore, there is a need for development of a method for suppressing resulfurization of a steel ladle in smelting an ultra-low sulfur steel by ladle flushing with an acid slag, which has a simple process and little deposition of slag in the steel ladle.
Disclosure of Invention
The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a method for suppressing resulfurization of a ladle by flushing the ladle with acidic slag, which has a simple procedure and is less likely to cause adhesion of slag in the ladle.
The technical scheme of the invention is as follows: a method for inhibiting resulfurization of a molten steel tank by flushing acid slag is characterized by comprising the following steps:
s1, selecting a steel grade with the component standard S of less than or equal to 0.045% as a steel grade for washing a tank, adding molten iron and common scrap steel with the sulfur content of 0.02-0.05% into a converter for converting, wherein the molten iron meets the condition that the S is less than or equal to 0.03% when entering the converter, controlling the sulfur content of tapping steel from the converter to meet the component standard of the steel grade for washing the tank, and tapping steel into a molten steel tank;
s2, heating the molten steel tank in a refining LF furnace;
s3, adjusting the alloy content of the refined molten steel to meet the component standard of the steel type of the tank washing, adding 2.5-4 kg of quartz sand into each ton of molten steel to make acid slag, and controlling the alkalinity of the slag to be less than 1.0;
and S4, casting the molten steel and turning the ladle in time, and immediately cleaning slag on the wall and slag on the edge of the molten steel ladle after the ladle is turned, so that the treated molten steel ladle can be used for producing the ultra-low sulfur steel.
Preferably, the heating process in step S2 adopts a tank wall slag melting operation, including the following steps:
switching on electrodes in the furnace for heating, and simultaneously blowing argon to quickly raise the temperature of the surface of the molten steel and the temperature of a hearth to the target refining temperature of the steel grade of the tank washing;
and (3) closing the argon, continuing heating the electrode for 3-5 minutes, opening the electrode, stopping heating, then rising to the position above the surface of molten steel, and waiting for 2-3 minutes to melt residues on the edge and wall of the molten steel tank into the molten steel by using the high temperature of the electrode and the hearth.
Further, in the argon blowing process in the step S2, the diameter of the argon flower is controlled to be 100-200 mm.
Further, in step S2, the electrode is raised to a position 300-500 mm above the surface of the molten steel.
Further, in step S2, the dust removal valve on the refining LF furnace is opened when the electrode is heated, and the dust removal valve on the refining LF furnace is closed when the electrode is not heated.
Preferably, in step S1, the steel grade for washing the tank is HRB400, 20MnK, WBZ500 or HPB 300.
Preferably, in step S4, the tank-turning time is less than or equal to 10 min.
Preferably, the method comprises the following steps:
s1, selecting deformed steel bar HRB400 as a steel grade of a washing tank, adding molten iron and common scrap steel with the sulfur content of 0.02-0.05% into a converter for converting, wherein the molten iron meets the condition that S is less than or equal to 0.03% when the molten iron is fed into the converter, controlling the sulfur content of steel discharged from the converter to meet the component standard of the steel grade of the washing tank, and discharging the steel into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
switching on an electrode in the furnace for heating, simultaneously blowing argon and controlling the diameter of an argon flower to be 100-200 mm, so that the temperature of the surface of molten steel and the temperature of a hearth are quickly raised to the target refining temperature of the steel grade of the tank washing;
after the argon is closed, the electrode continues to be heated for 3-5 minutes, the electrode is opened, the electrode rises to a position 300-500 mm above the surface of molten steel after the heating is stopped, and then the high temperature of the electrode and the hearth is utilized for waiting for 2-3 minutes to melt residues on the edge and the wall of the molten steel tank into the molten steel;
s3, adjusting the alloy content of the refined molten steel to meet the component standard of the steel type of the tank washing, adding 2.5-4.0 kg of quartz sand into each ton of molten steel to make acid slag, and controlling the alkalinity of the slag to be less than 1.0;
and S4, casting the molten steel and turning the molten steel in time, wherein the time for turning the molten steel is less than or equal to 10min, the slag on the wall and the edge of the molten steel tank is cleaned immediately after the molten steel is turned, and the treated molten steel tank can be used for producing the ultra-low sulfur steel.
The invention has the beneficial effects that:
1. the alkalinity of the molten slag is controlled to be less than 1.0 through the acid slag process, the sulfur content in the slag can be reduced, the acid slag has good fluidity, the residues on the wall and the bottom of the tank after casting are less, and the resulfurization of the molten steel tank during the production of the ultra-low sulfur steel can be effectively inhibited.
2. The sulfur content of the acid slag is 0.001-0.03%, the sulfur content of the alkaline slag is 1-3%, and the sulfur content of slag remained on the wall and bottom of the tank after the acid slag is washed is far lower than that of the alkaline slag.
3. If steel grades generating alkaline slag are adopted for washing the tank, deep desulfurization is needed before molten iron enters the furnace, the slag-off iron loss of the molten iron tank is 25-50 kg/t, the sulfur content of molten iron entering the acidic slag washing tank is lower than the upper limit of the sulfur content of the steel grades in the washing tank, deep desulfurization is not needed in the molten iron tank, and the slag-off iron loss is less than or equal to 20kg/t, so the slag-off iron loss is reduced, and the smelting cost is reduced.
Detailed Description
The following specific examples further illustrate the invention in detail. The steel types and the composition standards of the tank-washing steels used in examples 1 to 5 are shown in Table 1 below. The element contents in the invention all represent mass percent, and the sulfur content of the adopted common scrap steel is 0.02-0.05%.
TABLE 1
| Steel grade | Element(s) | C(％) | Si(％) | Mn(％) | P(％) | S(％) |
| HRB400 | Composition standard | 0.20～0.25 | 0.30～0.70 | 1.35～1.5 | ≤0.04 | ≤0.04 |
| 20MnK | Composition standard | 0.18～0.25 | 0.2～0.55 | 1.2～1.5 | ≤0.035 | ≤0.035 |
| WBZ500 | Ingredient standard | 0.18～0.24 | 0.15～0.5 | 1.1～1.3 | ≤0.03 | ≤0.03 |
| HPB300 | Composition standard | 0.18～0.22 | 0.25～0.45 | 0.45～0.9 | ≤0.044 | ≤0.044 |
Example 1
The invention provides a method for inhibiting resulfurization of a molten steel tank by flushing an acid slag tank, which comprises the following steps:
s1, selecting HRB400 as a steel type of a washing tank, adding molten iron with sulfur content of less than or equal to 0.03% (the sulfur content of the molten iron is 0.028% in the embodiment, and the slag skimming amount of the molten iron in each tank is 0.2t) and common scrap steel into a converter for converting, controlling the sulfur content of steel tapped from the converter to meet the component standard of the steel type of the washing tank (the component standard of the embodiment is that S is less than or equal to 0.04%, and the sulfur content of the actual steel tapped from the converter is 0.022%), and tapping into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
switching on electrodes in the furnace to heat (opening a dust removal valve on a refining LF furnace during heating), blowing argon and controlling the diameter of argon flowers to be 150mm, so that the temperature of the surface of molten steel and the temperature of a hearth are quickly raised to the target refining temperature (1672 ℃) of the steel type of the tank washing;
after the argon is closed, the electrode continues to be heated for 4 minutes, the electrode is opened and the heating is stopped, then the electrode rises to a position 300mm above the surface of the molten steel (when the heating is stopped, a dust removal valve on a refining LF furnace is closed), and after 2-3 minutes, the residues on the edge and the wall of the molten steel tank are melted into the molten steel by using the high temperature of the electrode and the hearth;
s3, adjusting the contents of alloy C, Si and Mn to meet the alloy requirement of steel types in a tank washing process according to the components of refined molten steel, and adding 3kg of quartz sand into each ton of molten steel to manufacture acid slag to obtain molten slag with the alkalinity of 0.83 and the sulfur content of the molten slag of 0.008 percent;
s4, casting the molten steel and turning the ladle in time for 8min, immediately cleaning the wall and the slag of the ladle edge after the ladle is turned, and using the treated molten steel ladle for producing ultra-low sulfur steel, wherein the chemical components of the steel product of the steel type of the ladle washing obtained at this time are shown in Table 2.
Example 2
The invention provides a method for inhibiting resulfurization of a molten steel tank by flushing an acid slag tank, which comprises the following steps:
s1, selecting 20MnK as a steel grade for washing a tank, adding molten iron with the sulfur content of less than or equal to 0.03% (the sulfur content of the molten iron is specifically 0.025% in the embodiment, and the slag skimming amount of each tank of the molten iron is 0t) and common scrap steel into a converter for blowing, controlling the sulfur content of steel tapped from the converter to meet the control standard of the steel grade for washing the tank (the control standard of the embodiment is that S is less than or equal to 0.035%, and the actual sulfur content of steel tapped from the converter is 0.033%), and tapping into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
closing electrodes in the furnace to heat (opening a dust removal valve on a refining LF furnace during heating), blowing argon and controlling the diameter of argon flowers to be 100mm, so that the temperature of the surface of molten steel and the temperature of a hearth are quickly raised to the target refining temperature (1661 ℃ in the embodiment) of the steel type of the tank washing;
after argon is closed, the electrode is continuously heated for 3 minutes, the electrode is opened and stops heating (when heating is stopped, a dust removal valve on a refining LF furnace is closed), then the electrode rises to a position 400mm above the surface of molten steel, and after 2-3 minutes, the residues on the edge and the wall of the molten steel tank are melted into the molten steel by using the high temperature of the electrode and the hearth;
s3, adjusting the contents of alloy C, Si and Mn according to the components of refined molten steel until the alloy requirements of steel types of a tank washing are met, and adding 4.0kg of quartz sand into each ton of molten steel to make acid slag to obtain molten slag with the alkalinity of 0.77 and the sulfur content of 0.007%;
s4, casting the molten steel and turning the ladle in time for 8min, immediately cleaning the wall and the slag of the ladle edge after the ladle is turned, and using the treated molten steel ladle for producing ultra-low sulfur steel, wherein the chemical components of the steel product of the steel type of the ladle washing obtained at this time are shown in Table 2.
Example 3
The invention provides a method for inhibiting resulfurization of a molten steel tank by flushing an acid slag tank, which comprises the following steps:
s1, selecting WBZ500 as a steel type of a washing tank, adding molten iron with the sulfur content of less than or equal to 0.03% (specifically, the sulfur content of the molten iron is 0.021% in the embodiment, the slag skimming amount of each tank of the molten iron is 0.5t) and common scrap steel into a converter for blowing, controlling the sulfur content of steel tapped from the converter to meet the control standard of the steel type of the washing tank (the control standard of the embodiment is that S is less than or equal to 0.03%, and the actual sulfur content of the steel tapped from the converter is 0.029%), and tapping into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
switching on electrodes in the furnace to heat (opening a dust removal valve on a refining LF furnace during heating), blowing argon and controlling the diameter of argon to be 100mm simultaneously, so that the temperature of the surface of molten steel and the temperature of a hearth are quickly raised to the target refining temperature (1682 ℃ in the embodiment) of the steel type of the tank washing;
after argon is closed, the electrode is continuously heated for 5 minutes, the electrode is opened and stops heating (when heating is stopped, a dust removal valve on a refining LF furnace is closed), then the electrode rises to a position 400mm above the surface of molten steel, and after 2-3 minutes, the residues on the edge and the wall of the molten steel tank are melted into the molten steel by using the high temperature of the electrode and the hearth;
s3, adjusting the contents of alloy C, Si and Mn to meet the alloy requirement of steel types in a tank washing according to the components of refined molten steel, and adding 3kg of quartz sand into each ton of molten steel to make acid slag to obtain molten slag with the alkalinity of 0.92 and the sulfur content of the molten slag of 0.015 percent;
s4, casting the molten steel and turning the ladle in time for 7min, immediately cleaning the wall and the slag of the ladle edge after the ladle is turned, and using the treated molten steel ladle for producing ultra-low sulfur steel, wherein the chemical components of the steel product of the steel type of the ladle washing obtained at this time are shown in Table 2.
Example 4
The invention provides a method for inhibiting resulfurization of a molten steel tank by flushing an acid slag tank, which comprises the following steps:
s1, selecting HRB400 as a steel grade of a washing tank, adding molten iron with the sulfur content of less than or equal to 0.03% (the sulfur content of the molten iron is specifically 0.026% in the embodiment, and the slag skimming amount of each molten iron is 0t) and common scrap steel into a converter for blowing, controlling the sulfur content of steel tapped from the converter to meet the control standard of the steel grade of the washing tank (the control standard of the embodiment is that S is less than or equal to 0.04%, and the actual sulfur content of the steel tapped from the converter is 0.030%), and tapping into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
closing electrodes in the furnace to heat (opening a dust removal valve on a refining LF furnace during heating), blowing argon and controlling the diameter of argon flowers to be 200mm simultaneously, so that the temperature of the surface of molten steel and a hearth is quickly raised to the target refining temperature (1666 ℃ in the embodiment) of the steel type of the tank washing;
after the argon is closed, the electrode is continuously heated for 4 minutes, the electrode is opened to stop heating (when the heating is stopped, a dust removal valve on a refining LF furnace is closed), then the electrode rises to a position 300mm above the surface of molten steel, and after 2-3 minutes, residues on the edge and the wall of the molten steel tank are melted into the molten steel by using the high temperature of the electrode and the hearth;
s3, adjusting the contents of alloy C, Si and Mn to meet the alloy requirement of steel types in a tank washing process according to the components of refined molten steel, and adding 2.5kg of quartz sand into each ton of molten steel to manufacture acid slag to obtain molten slag with the alkalinity of 0.88 and the sulfur content of 0.011 percent;
s4, casting the molten steel and turning the ladle in time for 7min, immediately cleaning the wall and the slag of the ladle edge after the ladle is turned, and using the treated molten steel ladle for producing ultra-low sulfur steel, wherein the chemical components of the steel product of the steel type of the ladle washing obtained at this time are shown in Table 2.
Example 5
The invention provides a method for inhibiting resulfurization of a molten steel tank by flushing an acid slag tank, which comprises the following steps:
s1, selecting HPB300 as a steel grade of a washing tank, adding molten iron with the sulfur content of less than or equal to 0.03% (the sulfur content of the molten iron is specifically 0.027% in the embodiment, and the slag skimming amount of each molten iron is 0t) and common scrap steel into a converter for blowing, controlling the sulfur content of converter tapping to meet the control standard of the steel grade of the washing tank (the control standard of the embodiment is that S is less than or equal to 0.044%, and the sulfur content of actual converter tapping is 0.017%), and tapping into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
closing electrodes in the furnace to heat (opening a dust removal valve on a refining LF furnace during heating), blowing argon and controlling the diameter of argon flowers to be 150mm simultaneously, so that the temperature of the surface of molten steel and the temperature of a hearth are quickly raised to the target refining temperature (1655 ℃ in the embodiment) of the steel type of the tank washing;
after the argon is closed, the electrode is continuously heated for 4 minutes, the electrode is opened to stop heating (when the heating is stopped, a dust removal valve on a refining LF furnace is closed), then the electrode rises to a position 400mm above the surface of molten steel, and after 2-3 minutes, the residues on the edge and the wall of the molten steel tank are melted into the molten steel by using the high temperature of the electrode and the hearth;
s3, adjusting the contents of alloy C, Si and Mn according to the components of refined molten steel until the alloy requirements of steel types in a tank washing tank are met, and adding 3kg of quartz sand into each ton of molten steel to make acid slag to obtain molten slag with the alkalinity of 0.75 and the sulfur content of 0.009%;
s4, casting the molten steel and turning the ladle in time for 9min, immediately cleaning the wall and the slag of the ladle edge after the ladle is turned, and using the treated molten steel ladle for producing ultra-low sulfur steel, wherein the chemical components of the steel product of the steel type of the ladle washing obtained at this time are shown in Table 2.
The compositions of the steel products of the steel grades for washing tanks obtained in the above examples 1 to 5 are shown in table 2 below.
TABLE 2
| Examples | C(％) | Si(％) | Mn(％) | P(％) | S(％) |
| 1 | 0.218 | 0.463 | 1.423 | 0.025 | 0.018 |
| 2 | 0.225 | 0.478 | 1.398 | 0.032 | 0.030 |
| 3 | 0.217 | 0.451 | 1.21 | 0.035 | 0.033 |
| 4 | 0.236 | 0.382 | 1.478 | 0.027 | 0.027 |
| 5 | 0.228 | 0.405 | 0.53 | 0.023 | 0.021 |
The process parameters in step S1 of the above examples 1-5 are shown in Table 3 below.
TABLE 3
| Examples | Molten iron in-furnace sulfur (%) | Slag quantity (t/per pot molten iron) | Tapping sulfur from converter (%) |
| 1 | 0.028 | 0.2 | 0.022 |
| 2 | 0.025 | 0 | 0.033 |
| 3 | 0.021 | 0.5 | 0.029 |
| 4 | 0.026 | 0 | 0.030 |
| 5 | 0.027 | 0 | 0.017 |
The process parameters of the refining process in step S2 of the above examples 1-5 are shown in Table 4 below.
TABLE 4
| Examples | Argon flower diameter (mm) | Heating time (min) | Furnace temperature (. degree. C.) |
| 1 | 150 | 4 | 1672 |
| 2 | 100 | 3 | 1661 |
| 3 | 100 | 5 | 1682 |
| 4 | 200 | 4 | 1666 |
| 5 | 150 | 4 | 1655 |
The process parameters of the acid slag in step S2 in the above examples 1 to 5 are shown in table 5 below.
TABLE 5
| Examples | Quartz sand (kg/ton steel) | Basicity of slag | Slag sulfur content (%) |
| 1 | 3 | 0.83 | 0.008 |
| 2 | 4.0 | 0.77 | 0.007 |
| 3 | 3 | 0.92 | 0.015 |
| 4 | 2.5 | 0.88 | 0.011 |
| 5 | 3 | 0.75 | 0.009 |
Claims (8)
1. A method for inhibiting resulfurization of a molten steel tank by flushing acid slag is characterized by comprising the following steps:
s1, selecting steel with the composition standard S not more than 0.045% as a steel type for washing a tank, adding molten iron and common scrap steel with the sulfur content of 0.02-0.05% into a converter for converting, wherein the molten iron meets the S not more than 0.03% when entering the converter, controlling the sulfur content of steel tapped from the converter to meet the composition standard of the steel type for washing the tank, and tapping the steel into a molten steel tank;
s2, heating the molten steel tank in a refining LF furnace;
s3, adjusting the alloy content of the refined molten steel to meet the component standard of the steel type of the tank washing, adding 2.5-4 kg of quartz sand into each ton of molten steel to make acid slag, and controlling the alkalinity of the molten slag to be less than 1.0;
and S4, casting the molten steel and turning over the ladle in time, immediately treating slag on the wall and slag on the edge of the molten steel ladle after the ladle is turned over, and enabling the treated molten steel ladle to be used for producing the ultra-low sulfur steel.
2. The method for suppressing resulfurization of molten steel ladle in acid slag flushing as claimed in claim 1, wherein the heating process in step S2 employs a ladle wall slagging operation, comprising the steps of:
switching on electrodes in the furnace to heat, and blowing argon to quickly raise the temperature of the surface of molten steel and the temperature of a hearth to a target refining temperature of a tank washing steel grade;
and (3) after the argon is closed, continuing heating the electrode for 3-5 minutes, opening the electrode to stop heating, then rising to the position above the surface of molten steel, and waiting for 2-3 minutes to melt residues on the edge and wall of the molten steel tank into the molten steel by using the high temperature of the electrode and the hearth.
3. The method for suppressing resulfurization of molten steel ladle in acid slag ladle as claimed in claim 2, wherein the diameter of argon blowings is controlled to be 100 to 200mm in the argon blowing process in step S2.
4. The method for suppressing resulfurization of molten steel ladle in acid slag flushing as claimed in claim 2, wherein the electrode is raised 300 to 500mm above the surface of molten steel in step S2.
5. The method for suppressing resulfurization of a molten steel ladle in which acid slag is poured into the ladle as set forth in claim 2, wherein in step S2, the dust removal valve of the refining LF furnace is opened when the electrode is heated, and the dust removal valve of the refining LF furnace is closed when the electrode is stopped.
6. The method for suppressing resulfurization of molten steel ladle in acid slag ladle flushing as claimed in claim 1, wherein in step S1, the steel grade for washing the ladle is HRB400, 20MnK, WBZ500 or HPB 300.
7. The method for suppressing the resulfurization of molten steel ladle in acid slag ladle as claimed in claim 1, wherein in step S4, the ladle-turning time is less than or equal to 10 min.
8. The method for inhibiting resulfurization of a molten steel ladle in acid slag flushing as claimed in claim 1, comprising the steps of:
s1, selecting deformed steel bar HRB400 as a steel grade for washing a tank, adding molten iron and common scrap steel with the sulfur content of 0.02-0.05% into a converter for converting, wherein the molten iron meets S (sulfur) content of less than or equal to 0.03% when entering the converter, controlling the sulfur content of steel tapped from the converter to meet the component standard of the steel grade for washing the tank, and tapping the steel into a molten steel tank;
s2, heating in a refining LF furnace, wherein the heating process adopts a tank wall slag melting operation, and the method specifically comprises the following steps:
switching on an electrode in the furnace for heating, simultaneously blowing argon and controlling the diameter of an argon flower to be 100-200 mm, so that the temperature of the surface of molten steel and the temperature of a hearth are quickly raised to the target refining temperature of the steel grade of the tank washing;
after the argon is closed, the electrode is continuously heated for 3-5 minutes, the electrode is opened and stops heating, then the electrode rises to a position 300-500 mm above the surface of molten steel, and then the high temperature of the electrode and the hearth is utilized for waiting for 2-3 minutes to melt residues on the edge and the wall of the molten steel tank into the molten steel;
s3, adjusting the alloy content of the refined molten steel to meet the component standard of the steel type of the tank washing, adding 2.5-4.0 kg of quartz sand into each ton of molten steel to make acid slag, and controlling the alkalinity of the molten slag to be less than 1.0;
and S4, casting the molten steel and turning the molten steel in time, wherein the time for turning the molten steel is less than or equal to 10min, the slag on the wall and the edge of the molten steel tank is cleaned immediately after the molten steel is turned, and the treated molten steel tank can be used for producing the ultra-low sulfur steel.
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| CN113604631A (en) * | 2021-07-16 | 2021-11-05 | 武汉钢铁有限公司 | Method for inhibiting refining resulfurization of low-sulfur steel in LF furnace |
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| CN104004883A (en) * | 2014-06-12 | 2014-08-27 | 鞍钢股份有限公司 | Method for accurately controlling sulfur content of molten steel in LF (ladle furnace) |
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Application publication date: 20220826 |