CN115198057B - Molten steel refining method of steel for ocean platform below EH36 - Google Patents
Molten steel refining method of steel for ocean platform below EH36 Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 177
- 239000010959 steel Substances 0.000 title claims abstract description 176
- 238000007670 refining Methods 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 115
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 496
- 229910052786 argon Inorganic materials 0.000 claims abstract description 248
- 238000007664 blowing Methods 0.000 claims abstract description 206
- 239000011449 brick Substances 0.000 claims abstract description 115
- 230000008569 process Effects 0.000 claims abstract description 78
- 238000009749 continuous casting Methods 0.000 claims abstract description 64
- 238000005516 engineering process Methods 0.000 claims abstract description 61
- 238000010079 rubber tapping Methods 0.000 claims abstract description 61
- 238000009423 ventilation Methods 0.000 claims abstract description 39
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 36
- 239000011575 calcium Substances 0.000 claims abstract description 36
- 239000012535 impurity Substances 0.000 claims abstract description 21
- 238000002360 preparation method Methods 0.000 claims abstract description 7
- 239000002893 slag Substances 0.000 claims description 65
- 239000007789 gas Substances 0.000 claims description 56
- 229910052782 aluminium Inorganic materials 0.000 claims description 42
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 42
- 239000000919 ceramic Substances 0.000 claims description 23
- 238000003756 stirring Methods 0.000 claims description 20
- 238000005070 sampling Methods 0.000 claims description 16
- 239000000523 sample Substances 0.000 claims description 15
- 238000007667 floating Methods 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- 239000001301 oxygen Substances 0.000 claims description 13
- 239000000956 alloy Substances 0.000 claims description 12
- 229910045601 alloy Inorganic materials 0.000 claims description 12
- 230000001105 regulatory effect Effects 0.000 claims description 12
- 239000006185 dispersion Substances 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 230000002308 calcification Effects 0.000 claims description 7
- 238000005266 casting Methods 0.000 claims description 7
- 230000001276 controlling effect Effects 0.000 claims description 6
- 239000005997 Calcium carbide Substances 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 238000007872 degassing Methods 0.000 claims description 5
- 238000006477 desulfuration reaction Methods 0.000 claims description 5
- 230000023556 desulfurization Effects 0.000 claims description 5
- 238000012840 feeding operation Methods 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 238000003723 Smelting Methods 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 230000003749 cleanliness Effects 0.000 abstract description 3
- 230000005611 electricity Effects 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 10
- 208000004434 Calcinosis Diseases 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000005272 metallurgy Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 229910052593 corundum Inorganic materials 0.000 description 3
- 239000010431 corundum Substances 0.000 description 3
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 3
- 229910052863 mullite Inorganic materials 0.000 description 3
- 230000024121 nodulation Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000002436 steel type Substances 0.000 description 3
- 238000009489 vacuum treatment Methods 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- ULGYAEQHFNJYML-UHFFFAOYSA-N [AlH3].[Ca] Chemical compound [AlH3].[Ca] ULGYAEQHFNJYML-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005406 washing Methods 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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/076—Use of slags or fluxes as treating agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
- B22D11/116—Refining the metal
- B22D11/117—Refining the metal by treating with gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
- B22D41/50—Pouring-nozzles
- B22D41/58—Pouring-nozzles with gas injecting means
-
- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
-
- 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
- C21C7/0006—Adding metallic additives
-
- 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
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
-
- 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
-
- 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
- C21C7/064—Dephosphorising; Desulfurising
-
- 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
- C21C7/10—Handling in a vacuum
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention belongs to the technical field of preparation of steel for ocean engineering, and particularly relates to a molten steel refining method for steel for ocean platforms below EH36, which is characterized in that calcium treatment is advanced from RH refining to LF refining furnaces, and meanwhile, a converter tapping process molten steel pre-refining technology, a continuous casting pouring process ladle ventilation upper nozzle pocket brick argon blowing metallurgical technology and a tundish ventilation upper nozzle pocket brick argon blowing metallurgical technology are adopted to perform multi-process argon blowing on the molten steel to remove impurities, so that the cleanliness of the molten steel is improved, the castability of the molten steel is improved, no wire feeding, no soft blowing or no feeding of the RH refining furnaces into the RH refining furnaces can be realized, LF and RH refining time is shortened, LF refining electricity consumption is reduced, and a green and low-carbon refining method for steel for ocean platforms below EH36 is realized.
Description
Technical Field
The invention relates to a molten steel refining method of steel for ocean platforms below EH36, belonging to the technical field of preparation of steel for ocean engineering.
Background
At present, the steel for ocean platforms below EH36 is basically domesticated, and an LF-RH refining treatment process route is generally adopted in the steelmaking process: smelting by a top-bottom combined blown converter, deoxidizing and slagging by an LF furnace, component and temperature fine tuning, soft blowing by the LF for 5min, discharging by an RH vacuum furnace, calcification treatment by the RH furnace, soft blowing by the RH furnace for more than or equal to 10min, discharging by a wide-thick plate continuous casting machine, and casting, wherein the refining treatment process time is longer, and the refining cost is higher. In order to reduce the production cost, some enterprises adopt molten steel refining methods of LF and RH furnaces without wire feeding and soft blowing, but after the process is adopted, the water gap nodulation phenomenon of a continuous casting machine is serious, the fluctuation of the pulling speed is large, the number of continuous casting furnaces is low, meanwhile, the impurities of B and D types in steel are more, the cleanliness of the molten steel is poor, the quality of casting blanks and the performance of steel are affected, and the seawater corrosion resistance is poor.
Chinese patent document CN109777917a (201910145116.7) discloses a calcium treatment advancing process of a refining furnace, the process comprising: and carrying out LF refining furnace treatment on the molten steel. And feeding calcium wires into the molten steel after the LF refining furnace treatment is finished, wherein the feeding quantity is 80-120 m/furnace. And transferring the molten steel fed with the calcium wire to an RH furnace for refining treatment. According to the calcium treatment advancing process of the refining furnace, for flaw detection steel types refined through the LF-RH double refining furnace process, after a calcium treatment procedure is moved to the LF refining furnace for treatment, before the RH refining furnace for treatment, calcium wires can be added to convert impurities into substances harmless to product performance, secondary pollution of the added calcium wires to molten steel is avoided, and the quality of finished steel billets is high. Although advancing the calcium treatment to the refining stage of the LF furnace can advance Al in the molten steel 2 O 3 The impurities are converted into low-melting-point liquid impurities, secondary pollution caused by adding calcium wires in RH refining is avoided, the liquid impurities float upwards in the RH vacuum treatment process, the number of the impurities can be effectively reduced, the RH refining time can be shortened to a certain extent, the RH vacuum treatment time is limited, the floating-up removal time of the impurities is insufficient, and the impurities in B class and D class are still more, so that the impurities in B class, B class and D class in the rolled material are reduced,The class D metallographic inclusions are all above 1.0 level, the performance of rolled materials is directly affected, the nozzle nodulation is serious, and the service life of the nozzle and the continuous casting number of a tundish are affected.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the molten steel refining method for the steel for the ocean platform below EH36, which advances the calcium treatment from RH refining to LF refining furnace, adopts the molten steel pre-refining technology in the converter tapping process, the ladle air-permeable upper nozzle pocket brick argon-blowing metallurgy and the tundish air-permeable upper nozzle pocket brick argon-blowing metallurgy technology to perform multi-procedure argon-blowing on the molten steel to remove impurities, improves the cleanliness of the molten steel, improves the castability of the molten steel, can realize no wire feeding, no soft blowing or no RH refining furnace feeding of the RH refining furnace, shortens the LF and RH refining time, reduces the LF refining power consumption, and realizes the green and low-carbon refining method for the steel for the ocean platform below EH 36.
The technical problems to be solved by the invention are realized by adopting the following technical scheme: the following process route is adopted: converter smelting-LF furnace refining-RH refining-wide and thick plate continuous casting, wherein the steel for ocean platforms below EH36 is the steel for ocean platforms below EH36, and comprises the following steel types but is not limited to: AH32/AH36 (Z25-Z35), DH32/DH36 (Z25-Z35), EH36 (Z25-Z35); advancing the calcium treatment from the RH refining furnace to the LF refining furnace;
adopting a converter tapping process molten steel pre-refining technology, a continuous casting pouring process ladle gas-permeable upper nozzle pocket brick argon blowing metallurgical technology and a tundish gas-permeable upper nozzle pocket brick argon blowing metallurgical technology to perform multi-procedure argon blowing on molten steel to remove impurities, specifically comprising the following steps:
in the converter smelting stage, a molten steel pre-refining technology in the converter tapping process is adopted: adding premelted refining slag to conduct premelted refining in the converter tapping process, wherein the premelted refining slag contains Al, and controlling the flow of argon blown from the bottom of the ladle in a sectional manner; the adoption of the molten steel pre-refining technology in the converter tapping process can ensure that the converter tapping temperature is reduced, so that the LF refining heating time is shortened, and the inclusion floating time in the LF refining stage is increased; firstly, the argon blowing flow is accurately controlled in stages, so that the argon blowing flow and the argon blowing time are reduced, and the floating of the inclusion is facilitated; secondly, aluminum oxide reaction emits certain heat in the reaction process of premelted refining slag, so that the temperature drop compensation of molten steel is realized, and the LF refining time is further shortened by slag formation in advance in a converter;
the ladle pouring stage adopts the argon blowing metallurgical technology of a ladle ventilation upper nozzle pocket brick during the continuous casting pouring process: in the ladle pouring process, arranging an argon blowing structure at the tapping hole for blowing argon;
the pouring stage of the tundish adopts the argon blowing metallurgical technology of the tundish ventilation upper nozzle pocket brick: in the pouring process of the tundish, an argon blowing structure is arranged at a tapping hole of the tundish to blow argon.
The invention preferably, 1) the molten steel pre-refining technology in the converter tapping process specifically comprises the following steps: in the tapping process of the top-bottom combined blown converter, adding 1.5-2.3 kg/t molten steel of premelted refining slag along with steel flow, and after 3 minutes before the end point, blowing argon into the bottom of a ladle, wherein the ladle is a continuous casting ladle, and controlling the flow of the argon is divided into six stages:
the stage 1 is a tapping starting stage, and adopts smaller bottom blowing flow, wherein the argon blowing flow is 30-50 NL/min, and the argon blowing time is 50-60 seconds;
the stage 2 is a deoxidizer and alloy adding stage, a larger bottom blowing flow is adopted to promote the alloy to be melted rapidly, the argon blowing flow is 150-200 NL/min, and the argon blowing time is 30-50 seconds;
the stage 3 is a slag charge adding stage, the bottom blowing flow is properly reduced, the slag charge is ensured to be normally melted and not to be involved in molten steel, the argon blowing flow is 100-150 NL/min, and the argon blowing time is 30-40 seconds;
the stage 4 is an inclusion floating stage, and proper bottom blowing flow is adopted to promote the deoxidized product to float upwards rapidly, the argon blowing flow is 50-100 NL/min, and the argon blowing time is 40-50 seconds;
the stage 5 is a tapping slag-stopping stage, and adopts smaller bottom blowing flow, wherein the argon blowing flow is 30-50 NL/min, and the argon blowing time is 50-60 seconds;
the stage 6 is a stage from the finish of tapping to the hanging-away of molten steel, the ladle adopts smaller bottom blowing flow to further promote the floating of inclusions, the argon blowing flow is 50-100 NL/min, and the argon blowing time is 50-60 seconds; in the tapping process of the converter, according to different tapping time, the ladle bottom blowing time in each stage is adapted to the tapping operation of the converter, different alloy and slag materials are selected to have different bottom blowing flow rates, so that the alloy, deoxidizer and slag materials are promoted to be melted rapidly, the alloy yield and slag forming speed are improved, and good metallurgical effect is ensured;
2) The argon blowing metallurgical technology of the ladle ventilation upper nozzle pocket brick in the continuous casting and pouring process specifically comprises the following steps: adopting a ladle ventilation upper nozzle pocket brick with an argon blowing function to replace the existing ladle upper nozzle pocket brick, after the ladle is lifted to a position to be poured of a continuous casting rotary table, communicating an air inlet pipe of the ladle ventilation upper nozzle pocket brick with an argon gas source pipeline, blowing argon gas into the ladle while pouring the ladle, adjusting the argon gas flow to be 5-10 NL/min after the argon blowing time is 20-25 minutes, closing the argon gas after the ladle is rotated to the position to be poured from the pouring position of the continuous casting rotary table, and disconnecting the air inlet pipe of the ladle ventilation upper nozzle pocket brick from the argon gas source pipeline;
3) The argon blowing metallurgical technology of the tundish upper nozzle pocket brick in the continuous casting and pouring process specifically comprises the following steps: adopting a continuous casting tundish air-permeable upper nozzle pocket brick with argon blowing function to replace the existing tundish upper nozzle pocket brick, when the tundish pocket is in a baking position, communicating an air inlet pipe of the tundish upper nozzle pocket brick with an argon gas source pipeline, blowing argon gas into the tundish upper nozzle pocket brick while baking, and when molten steel in the tundish reaches the liquid level of normally poured molten steel, regulating the argon gas flow to 12-15 NL/min, closing the nozzle after the ladle is closed and stopped pouring, and disconnecting the air inlet pipe of the tundish upper nozzle pocket brick from the argon gas source pipeline after the tundish is closed and stopped pouring.
The LF refining furnace adopts high alkalinity and high reducing top slag, and the rapid desulfurization technology of high-flow stirring: aluminum particles, aluminum slag and calcium carbide are adopted to regulate slag, an aluminum feeding wire is adopted to increase aluminum, and the final slag alkalinity is controlled to be more than 2.2;
the key points of operation control are as follows: stirring the large argon gas entering the station for 1 to 2 minutes, regulating the pressure of the argon gas to 0.8 to 1.5Mpa, regulating the pressure of the argon gas to 0.2 to 0.4Mpa, measuring the temperature and oxygen by adopting a low-oxygen probe, and carrying out aluminum wire feeding operation according to the measured aluminum content and target components; then electrifying to remove slag, and stirring with large argon for 2-3 minutes before sampling 1; carrying out power-on and temperature rise during the component of the sample 1; according to the sample 1, carrying out aluminum preparation operation or not, stirring for 1-2 minutes by large argon before sampling 2, and carrying out fine adjustment on the temperature;
feeding wire for calcification, sampling and soft blowing, wherein the refining time is controlled to be 40-50 minutes, and the soft blowing time is controlled to be 5-8 minutes.
The invention preferably determines the feeding amount according to the control requirement of the calcium content in refined molten steel, the calcium content in feeding wires and the yield, and feeds the wires according to 0.50-0.90 m/ton of molten steel with high calcium content or 0.75-1.5 m/ton of molten steel with calcium and aluminum content.
In the invention, the RH refining adopts the technology of removing impurities in vacuum in an RH refining furnace: the treatment operation mode is adopted, a low-high-low circulation mode is selected, and the treatment operation mode is used for degassing and removing impurities in the prior art, wherein the vacuum degree is within 133Pa, the time is 15-20 minutes, and the RH ensures that the pure degassing time is more than 5 minutes.
The invention preferably selects steel types AH36 and DH36, the thickness of the rolled material is less than 30mm, the compression ratio of the rolled material is small, the influence of inclusions in the steel on the performance of the rolled material is small, the steel is not treated by an RH refining furnace, the process flow is shortened, and the refining cost is reduced.
Preferably, the ladle air-permeable upper nozzle pocket brick with argon blowing function is one of the ladle microporous ceramic rod air-permeable upper nozzle pocket brick of LF refining ladle described in the prior art CN111774560B (202010726676.4) or the ladle dispersion ring air-permeable upper nozzle pocket brick described in the prior art CN109732074A (201910126691.2). The invention is characterized in that the argon blowing control method is different from the prior art, the technical effect is different, the argon blowing flow is controlled in two sections, the flow for removing impurities by blowing argon is small and constant, and the prior art linearly adjusts the argon blowing flow according to the change of the net weight of molten steel in the ladle, and the invention has the advantage of high impurity removing rate.
In the invention, preferably, the continuous casting tundish air-permeable upper nozzle pocket brick is one of a continuous casting tundish dispersion-type air-permeable ring upper nozzle pocket brick described in the prior art CN106041045B (201610634270.7) or a continuous casting tundish air-permeable ceramic pipe upper nozzle pocket brick described in the prior art CN106041044B (2016610634268. X). The invention is characterized in that firstly, argon is blown in the baking process of the continuous casting tundish, and the argon flow is 5-10 NL/min, and has the beneficial effects that the technical problems that steel slag adhered on the cover of the tundish is melted and falls off on the working surface of the air-permeable upper nozzle pocket brick of the tundish, thereby blocking the air holes and seriously affecting air permeability in the baking process of the tundish, and secondly, when the molten steel in the tundish reaches the liquid level of normally poured molten steel, the argon flow is 12-15 NL/min, and the argon blowing flow is smaller, thereby solving the technical problems of slag coiling and secondary oxidation of the molten steel caused by the blowing of the liquid level of the molten steel due to the reduction of the liquid level in the tundish in the ladle exchange process of the ladle are solved.
Preferably, the premelted refining slag contains CaO 40-50% and Al 2 O 3 The content is 35-40%, al content is 5-7%, siO 2 (％)≤5，Fe 2 O 3 (%) is less than or equal to 1.5, mgO (%) is less than or equal to 2, P and S (%) is less than or equal to 0.02, and water (%) is less than or equal to 1.0. Metal aluminum is added into the premelted refining slag, the Al content is 5-7%, and certain heat can be released in the reaction process of the metal aluminum and oxygen, so that the temperature drop of molten steel is compensated.
The invention has the beneficial effects that:
1) The invention relates to a molten steel refining method of steel for ocean platforms below EH36, which adopts a molten steel pre-refining technology in the tapping process of a converter outside refining, a ladle ventilation upper nozzle pocket brick argon blowing metallurgical technology in the continuous casting pouring process and a tundish ventilation upper nozzle pocket brick argon blowing metallurgical technology to perform multi-procedure argon blowing on molten steel to remove impurities; metal aluminum is added into premelted refining slag added in the molten steel premelting technology in the tapping process of the converter, the reaction and the heat release of the metal aluminum and oxygen can compensate the temperature drop of the molten steel, and the argon blowing flow and the argon blowing time of a ladle are reduced by accurately controlling the argon blowing stage by stage in the tapping process, so that the tapping temperature drop of the converter is further reduced, and the electric heating and heating time of LF refining is shortened; after the LF refining is finished and calcium treatment is carried out, the inclusions in the molten steel are basically converted into 12CaO.7A1 2 0 3 In the nearby low-melting-point area, the inclusion is liquid in molten steel, and in the RH vacuum treatment process, the liquid inclusion floats up in a large amount, and the ladle gas-permeable upper nozzle pocket brick argon blowing metallurgical technology or the tundish gas-permeable upper nozzle pocket brick argon blowing metallurgical technology is adopted in the continuous casting and pouring processArgon blowing is carried out in the tapping stage, so that liquid calcium aluminate inclusions can be fully removed by floating upwards, and only a small amount of high-melting-point CaS-CaO inclusions are left in molten steel, so that the proportion of B, D inclusions which are less than or equal to 0.5 level is 100%, and the technical problem of high B, D inclusions in the prior art is solved.
2) According to the invention, the calcium treatment is advanced from an RH refining furnace to an LF refining furnace, and the multi-procedure argon blowing and inclusion removal are carried out on the molten steel by adopting a converter tapping process molten steel pre-refining technology, a continuous casting pouring process ladle gas-permeable upper nozzle pocket brick argon blowing metallurgical technology and a tundish gas-permeable upper nozzle pocket brick argon blowing metallurgical technology, so that the RH refining furnace is free of wire feeding, soft blowing or entering the RH refining furnace, the tapping temperature of the LF refining furnace is correspondingly reduced due to the reduction of the RH refining time, the calcium treatment advancing technology of the LF refining furnace is superior to that of the prior art CN109777917A (201910145116.7), the calcium treatment advancing technology of the refining furnace is used for refining the molten steel for the ocean platform below EH36, the steel outlet temperature of the LF refining furnace is reduced by 5-12 ℃ by the same ratio, the LF refining electrifying time is shortened by the same ratio by 2-6 minutes, the LF refining ton steel electricity consumption is reduced by the same ratio by more than 4.2kwh, the RH refining time is reduced by the same ratio by more than 7.3 minutes, and the green, low-carbon and high-efficiency production is realized by the same advantage.
3) According to the invention, the ladle air-permeable upper nozzle pocket brick with argon blowing function is adopted to replace the existing ladle upper nozzle pocket brick, the tundish upper nozzle pocket brick with argon blowing function is adopted to replace the existing tundish upper nozzle pocket brick, argon blowing is carried out by utilizing the ladle air-permeable upper nozzle pocket brick and the tundish upper nozzle pocket brick in the casting process, most argon bubbles formed by argon blowing upwards form an annular air curtain barrier, the molten steel which is about to enter the ladle upper nozzle and the tundish upper nozzle is subjected to air washing, the floating and removal of inclusions are promoted, and a certain amount of argon bubbles respectively enter the ladle long nozzle and the tundish submerged nozzle along with the steel flow to form stable and continuous annular air flows, so that the problems of ladle long nozzle and tundish submerged nozzle nodulation are restrained, the service lives of the ladle long nozzle and the tundish submerged nozzle are prolonged, and the service lives of the tundish submerged nozzle are improved by more than 2 hours in the same ratio.
Detailed Description
The invention is further illustrated, but not limited, by the following examples. The invention, not described in detail, may be employed in any of the prior art. It should be noted that: the premelted refining slag is a commercial product and comprises the following components: caO content is 40-50%, al 2 O 3 The content is 35-40%, al content is 5-7%, siO 2 (％)≤5，Fe 2 O 3 (%) is less than or equal to 1.5, mgO (%) isless than or equal to 2, P and S (%) isless than or equal to 0.02, and the component proportion of premelted refining slag is selected according to the purpose of the invention.
Example 1:
steel grade: EH36, the thickness of the rolled stock was 50mm.
A molten steel refining method of steel EH36 for ocean platforms adopts the following process routes: converter smelting-LF furnace refining-RH refining-wide and thick plate continuous casting machine casting; the method comprises the steps of advancing calcium treatment from an RH refining furnace to an LF refining furnace, wherein the RH refining furnace is not fed and does not perform soft blowing, and carrying out multi-procedure argon blowing to molten steel to remove impurities by adopting a molten steel pre-refining technology in the tapping process of a converter, an argon blowing metallurgical technology of a ladle ventilation upper nozzle pocket brick in the continuous casting process and an argon blowing metallurgical technology of a tundish ventilation upper nozzle pocket brick, and specifically comprises the following steps:
1) The tapping process of the top-bottom combined blown converter adopts a molten steel pre-refining technology: adding premelted refining slag to conduct premelted refining in the converter tapping process, wherein the premelted refining slag contains Al, the flow of argon blown from the bottom of a ladle is controlled in a segmented mode, specifically, 2.3kg/t molten steel of the premelted refining slag is added along with the steel flow, and the premelted refining slag is added 3 minutes before the end point, wherein the CaO content is 40-50%, and the Al content is 2 O 3 The content is 35-40%, al content is 5-7%, siO 2 (％)≤5，Fe 2 O 3 (%) is less than or equal to 1.5, mgO (%) is less than or equal to 2, P and S (%) is less than or equal to 0.02, and water (%) is less than or equal to 1.0. Argon is blown into the bottom of the steel ladle, and the argon flow control is divided into six stages:
the stage 1 is a tapping starting stage, and adopts a smaller bottom blowing flow, wherein the argon blowing flow is 50NL/min, and the argon blowing time is 50 seconds.
The stage 2 is a deoxidizer and alloy adding stage, and adopts a larger bottom blowing flow to promote the alloy to be melted quickly, wherein the argon blowing flow is 200NL/min, and the argon blowing time is 30 seconds.
The stage 3 is a slag charge adding stage, the bottom blowing flow is properly reduced, the slag charge is ensured to be normally melted and not to be involved in molten steel, the argon blowing flow is 150NL/min, and the argon blowing time is 30 seconds.
The stage 4 is an inclusion floating stage, and proper bottom blowing flow is adopted to promote the deoxidized product to float up quickly, the argon blowing flow is 100NL/min, and the argon blowing time is 40 seconds.
The stage 5 is a tapping slag-stopping stage, the argon blowing flow is 50NL/min, and the argon blowing time is 50 seconds.
And the stage 6 is a stage from the end of tapping to the lifting of molten steel, argon is blown to the bottom of the steel ladle, the floating of inclusions is further promoted by adopting smaller bottom blowing flow, the argon blowing flow is 100NL/min, and the argon blowing time is 60 seconds.
2) The LF refining furnace adopts high alkalinity and high reducibility top slag, and a rapid desulfurization technology of large-flow stirring: aluminum particles, aluminum slag and calcium carbide are adopted to regulate slag, an aluminum feeding wire is adopted to increase aluminum, and the final slag alkalinity is controlled to be more than 2.2.
The key points of operation control are as follows: stirring the argon gas for 2 minutes at the station, regulating the argon pressure to 0.4Mpa, measuring the temperature and oxygen by adopting a low-oxygen probe, and carrying out aluminum wire feeding operation according to the measured aluminum content and target components (Als target is 0.020 percent and the internal control range is 0.015-0.045 percent); then electrifying to remove slag, and stirring with large argon for 2 minutes before sampling 1; carrying out power-on and temperature rise during the component of the sample 1; according to the sample 1, carrying out aluminum preparation operation or not, stirring for 1 minute by using large argon before sampling 2, and carrying out fine adjustment on the temperature; feeding wire for calcification, sampling and soft blowing.
And determining the feeding amount according to the control requirement of calcium content in refined molten steel, the calcium content in feeding wires and the yield, feeding 0.90 m/ton of molten steel with high calcium content, and controlling the refining time to 45 minutes, wherein the soft blowing time is controlled to 6 minutes.
3) The RH refining furnace carries out vacuum inclusion removal technology: by adopting the treatment operation mode, a low-high-low circulation mode is selected, the vacuum degree is within 133Pa, the time is 20 minutes, and the RH ensures that the pure degassing time is more than 5 minutes.
4) Air-permeable ladle nozzle seat in continuous casting processBrick argon blowing metallurgical technology: in the ladle pouring process, an argon blowing structure is arranged at a steel tapping hole to blow argon, specifically, a ladle air-permeable upper nozzle pocket brick with an argon blowing function is adopted to replace the existing ladle upper nozzle pocket brick, wherein the ladle air-permeable upper nozzle pocket brick is a ladle dispersion ring air-permeable upper nozzle pocket brick in the prior art CN109732074A (201910126691.2), and a dispersion air-permeable ring is embedded in the ladle dispersion ring air-permeable upper nozzle pocket brick; the cross section of the dispersion type ventilation ring is in a circular ring shape, the longitudinal section of the dispersion type ventilation ring is in a right trapezoid shape, the width x of the lower part of the circular ring is 50mm, the width y of the upper part of the circular ring is 46mm, the height h of the circular ring is 160mm, the dispersion type ventilation ring is produced by taking high-purity corundum, mullite and the like as main raw materials and adopting an isostatic compaction process, and the volume density is more than or equal to 2.80g/cm 3 。
After the steel ladle is lifted to the position to be poured of the continuous casting rotary table, communicating an air inlet pipe of the steel ladle air inlet brick cup with an argon gas source pipeline, blowing argon gas into the steel ladle while pouring the steel ladle, wherein the argon gas flow is 30NL/min, adjusting the argon gas flow to 7NL/min after the argon gas blowing time is 22 minutes, and closing the argon gas after the steel ladle is transferred to the position to be poured from the pouring position of the continuous casting rotary table, and disconnecting the air inlet pipe of the steel ladle air inlet brick cup from the argon gas source pipeline.
5) Argon blowing metallurgical technology for tundish upper nozzle pocket brick in the continuous casting and pouring process: in the pouring process of the tundish, an argon blowing structure is arranged at a tapping hole of the tundish for blowing argon, specifically, a continuous casting tundish air-permeable upper nozzle pocket brick with an argon blowing function is adopted to replace the existing tundish upper nozzle pocket brick, the continuous casting tundish air-permeable upper nozzle pocket brick is a continuous casting tundish dispersion-type air-permeable ring upper nozzle pocket brick in the prior art CN106041045B (201610634270.7), and a dispersion-type air-permeable ring is embedded in the continuous casting tundish dispersion-type air-permeable ring upper nozzle pocket brick; the whole diffuse-type ventilation ring is in a circular ring shape, the longitudinal section of the diffuse-type ventilation ring is in a right trapezoid shape, the width x of the upper end of the circular ring is 30mm, the width y of the lower end of the circular ring is 40mm, the height h of the circular ring is 90mm, the diffuse-type ventilation ring is formed by adopting high-purity corundum, mullite and the like as main raw materials in a mechanical pressing mode, and the volume density is more than or equal to 2.6g/cm 3 The high-temperature compressive strength is more than or equal to 50Mpa, the apparent porosity is 25-28%, al 2 O 3 +SiO 2 +Cr 2 O 3 The content is more than or equal to 94 percent.
When the tundish seat ladle is in a baking position, an air inlet pipe of a tundish upper nozzle seat brick is communicated with an argon gas source pipeline, argon is blown in during baking, the argon flow is 10NL/min, when molten steel in the tundish reaches the liquid level of normally poured molten steel, the argon flow is regulated to 15NL/min, after the ladle is closed and stopped pouring, argon is closed, and after the tundish is closed and stopped pouring, the air inlet pipe of the tundish upper nozzle seat brick is disconnected with the argon gas source pipeline.
Example 2
As described in example 1, the difference is that:
steel grade: DH36, thickness of rolled stock was 50mm.
A molten steel refining method of steel DH36 for ocean platforms adopts the following process routes: converter smelting-LF furnace refining-RH refining-wide and thick plate continuous casting machine casting; the method comprises the following steps of advancing calcium treatment from an RH refining furnace to an LF refining furnace, carrying out multi-procedure argon blowing to molten steel to remove impurities by adopting a molten steel pre-refining technology in the tapping process of a converter, an argon blowing metallurgical technology of a ladle ventilation upper nozzle pocket brick in the continuous casting process and an argon blowing metallurgical technology of a tundish ventilation upper nozzle pocket brick, wherein the RH refining furnace is not fed with wires and does not carry out soft blowing, and the method comprises the following steps:
1) The tapping process of the top-bottom combined blown converter adopts a molten steel pre-refining technology: adding premelted refining slag to conduct premelted refining in the converter tapping process, wherein the premelted refining slag contains Al, the flow of argon blown from the bottom of the ladle is controlled in a segmented mode, specifically, 1.5kg/t molten steel of the premelted refining slag is added along with the steel flow, the premelted refining slag is added 3 minutes before the end point, the argon blown from the bottom of the ladle is controlled, and the argon flow is controlled in six stages:
the stage 1 is a tapping starting stage, and adopts a smaller bottom blowing flow, wherein the argon blowing flow is 30NL/min, and the argon blowing time is 60 seconds.
The stage 2 is a deoxidizer and alloy adding stage, and adopts a larger bottom blowing flow to promote the alloy to be melted rapidly, wherein the argon blowing flow is 150NL/min, and the argon blowing time is 50 seconds.
The stage 3 is a slag charge adding stage, the bottom blowing flow is properly reduced, the slag charge is ensured to be normally melted and not to be involved in molten steel, the argon blowing flow is 100NL/min, and the argon blowing time is 30 seconds.
The stage 4 is an inclusion floating stage, and proper bottom blowing flow is adopted to promote the deoxidized product to float up quickly, the argon blowing flow is 50NL/min, and the argon blowing time is 50 seconds.
The stage 5 is a tapping slag-stopping stage, the argon blowing flow is 30NL/min, and the argon blowing time is 60 seconds.
And the stage 6 is a stage from the finish of tapping to the lifting of molten steel, the ladle adopts smaller bottom blowing flow, the floating of inclusions is further promoted, the argon blowing flow is 50NL/min, and the argon blowing time is 60 seconds.
2) The LF refining furnace adopts high alkalinity and high reducibility top slag, and a rapid desulfurization technology of large-flow stirring: aluminum particles, aluminum slag and calcium carbide are adopted to regulate slag, an aluminum feeding wire is adopted to increase aluminum, and the final slag alkalinity is controlled to be more than 2.2. The key points of operation control are as follows: stirring the large argon gas at a station for 1 minute, regulating the argon gas pressure to be 0.2Mpa, adopting a low-oxygen probe to measure temperature and oxygen, and carrying out aluminum wire feeding operation according to the measured aluminum content and target components (Als target is 0.020 percent and the internal control range is 0.015-0.045 percent); then electrifying to remove slag, and stirring with large argon for 1.5 minutes before sampling 1; carrying out power-on and temperature rise during the component of the sample 1; according to the sample 1, carrying out aluminum preparation operation or not, stirring for 1.5 minutes by large argon before sampling 2, and carrying out fine adjustment on the temperature; feeding wire for calcification, sampling and soft blowing.
And determining the wire feeding quantity according to the control requirement of the calcium content in refined molten steel, the calcium content in the wire feeding and the yield, feeding 1.0 m/ton of molten steel to the calcium aluminum wire, and controlling the refining time to 40 minutes, wherein the soft blowing time is controlled to 5 minutes.
3) The RH refining furnace carries out vacuum inclusion removal technology: by adopting the treatment operation mode, a low-high-low circulation mode is selected, the vacuum degree is within 133Pa, the time is 15 minutes, and the RH ensures that the pure degassing time is more than 5 minutes.
4) Argon blowing metallurgical technology for the permeable upper nozzle pocket brick of the steel ladle in the continuous casting and pouring process comprises the following steps: in the ladle pouring process, an argon blowing structure is arranged at a steel tapping hole to blow argon, specifically, a ladle ventilation upper nozzle pocket brick with an argon blowing function is adopted to replace the existing ladle upper nozzle pocket brick, wherein the ladle ventilation upper nozzle pocket brick is an LF refined ladle microporous ceramic rod ventilation nozzle pocket brick in the prior art CN111774560B (202010726676.4), and microporous ceramic rods are embedded in the LF refined ladle microporous ceramic rod ventilation nozzle pocket brick; the number of the microporous ceramic rods is 10, the microporous ceramic rods are cylindrical and are uniformly distributed in the ladle nozzle pocket brick body in an annular shape, the diameter d of each ceramic rod is 35mm, and the height h of each ceramic rod is 160mm.
After the steel ladle is lifted to a position to be poured of the continuous casting rotary table, communicating an air inlet pipe of the steel ladle air inlet brick cup with an argon gas source pipeline, blowing argon gas into the steel ladle while pouring the steel ladle, wherein the argon gas flow is 25NL/min, adjusting the argon gas flow to 5NL/min after the argon gas blowing time is 20 minutes, and closing the argon gas after the steel ladle is transferred to the position to be poured from the pouring position of the continuous casting rotary table, and disconnecting the air inlet pipe of the steel ladle air inlet brick cup from the argon gas source pipeline.
5) Argon blowing metallurgical technology for tundish upper nozzle pocket brick in the continuous casting and pouring process: in the pouring process of the tundish, an argon blowing structure is arranged at a tapping hole of the tundish to blow argon, specifically, a continuous casting tundish air upper nozzle pocket brick with an argon blowing function is adopted to replace the existing tundish upper nozzle pocket brick, the continuous casting tundish air upper nozzle pocket brick is a continuous casting tundish air upper nozzle pocket brick of the prior art CN106041044B (2016610634268. X), and an air ceramic tube is embedded in the continuous casting tundish air upper nozzle pocket brick; the gas-permeable ceramic tubes are uniformly distributed along the circumferential direction of the water gap pocket bricks on the gas-permeable ceramic tubes of the continuous casting tundish, the gas-permeable ceramic tubes are cylindrical, the outer diameter phi of the cylinder is 16mm, and the height h of the ceramic tubes is 105mm; the diameter of the air blowing channels is 0.14mm, the air blowing channels are uniformly distributed in 3 concentric circles, the number of the air blowing channels of the 1 st ring is 5 from inside to outside, the number of the air blowing channels of the 2 nd ring is 10, and the number of the air blowing channels of the 3 rd ring is 10.
When the tundish seat ladle is in a baking position, an air inlet pipe of a tundish upper nozzle seat brick is communicated with an argon gas source pipeline, argon is blown in during baking, the argon flow is 5NL/min, when molten steel in the tundish reaches the liquid level of normally poured molten steel, the argon flow is regulated to 12NL/min, after the ladle is closed and stopped pouring, argon is closed, and after the tundish is closed and stopped pouring, the air inlet pipe of the tundish upper nozzle seat brick is disconnected with the argon gas source pipeline.
Example 3
As described in example 1, the difference is that:
steel grade: AH36, 30mm thick rolled stock.
The molten steel refining method of the steel AH36 for the ocean platform adopts the following process route: converter smelting-LF furnace refining-RH refining-wide and thick plate continuous casting machine casting; in the later stage of LF refining, wire feeding calcification, sampling and soft blowing are carried out, an RH refining furnace is not fed, a converter tapping process molten steel pre-refining technology, a continuous casting pouring process ladle ventilation upper nozzle pocket brick argon blowing metallurgy and a tundish ventilation upper nozzle pocket brick argon blowing metallurgy technology are adopted to carry out multi-procedure argon blowing to molten steel to remove impurities, and the method comprises the following steps:
1) The tapping process of the top-bottom combined blown converter adopts a molten steel pre-refining technology: adding premelted refining slag to conduct premelted refining in the converter tapping process, wherein the premelted refining slag contains Al, the flow of argon blown from the bottom of the ladle is controlled in a segmented mode, specifically, 2.0kg/t molten steel of the premelted refining slag is added along with the steel flow, the premelted refining slag is added 3 minutes before the end point, the argon blown from the bottom of the ladle is controlled, and the argon flow is controlled in six stages:
the stage 1 is a tapping starting stage, and the argon blowing flow is 40NL/min and the argon blowing time is 40 seconds by adopting smaller bottom blowing flow.
The stage 2 is a deoxidizer and alloy adding stage, and adopts a larger bottom blowing flow to promote the alloy to be melted rapidly, wherein the argon blowing flow is 170NL/min, and the argon blowing time is 40 seconds.
The stage 3 is a slag charge adding stage, the bottom blowing flow is properly reduced, the slag charge is ensured to be normally melted and not to be involved in molten steel, the argon blowing flow is 120NL/min, and the argon blowing time is 35 seconds.
The stage 4 is an inclusion floating stage, and proper bottom blowing flow is adopted to promote the deoxidized product to float up quickly, the argon blowing flow is 70NL/min, and the argon blowing time is 45 seconds.
The stage 5 is a tapping slag-stopping stage, the argon blowing flow is 40NL/min, and the argon blowing time is 55 seconds.
And the stage 6 is a stage from the finish of tapping to the lifting of molten steel, the ladle adopts smaller bottom blowing flow, the floating of inclusions is further promoted, the argon blowing flow is 60NL/min, and the argon blowing time is 55 seconds.
2) The LF refining furnace adopts high alkalinity and high reducibility top slag, and a rapid desulfurization technology of large-flow stirring: aluminum particles, aluminum slag and calcium carbide are adopted to regulate slag, an aluminum feeding wire is adopted to increase aluminum, and the final slag alkalinity is controlled to be more than 2.2.
The key points of operation control are as follows: stirring the large argon gas at a station for 1 minute, regulating the argon gas pressure to be 0.2Mpa, adopting a low-oxygen probe to measure temperature and oxygen, and carrying out aluminum wire feeding operation according to the measured aluminum content and target components (Als target is 0.020 percent and the internal control range is 0.015-0.045 percent); then electrifying to remove slag, and stirring with large argon for 2 minutes before sampling 1; carrying out power-on and temperature rise during the component of the sample 1; according to the sample 1, carrying out aluminum preparation operation or not, stirring for 1 minute by using large argon before sampling 2, and carrying out fine adjustment on the temperature; feeding wire for calcification, sampling and soft blowing.
Feeding high calcium line 0.50 m/ton molten steel, refining time is controlled to be 40 minutes, wherein soft blowing time is controlled to be 5 minutes; the refining time was controlled at 42 minutes, with the soft blow time controlled at 8 minutes.
3) Argon blowing metallurgical technology for the permeable upper nozzle pocket brick of the steel ladle in the continuous casting and pouring process comprises the following steps: in the ladle pouring process, an argon blowing structure is arranged at a steel tapping hole to blow argon, specifically, a ladle ventilation upper nozzle pocket brick with an argon blowing function is adopted to replace the existing ladle upper nozzle pocket brick, wherein the ladle ventilation upper nozzle pocket brick is an LF refined ladle microporous ceramic rod ventilation nozzle pocket brick in the prior art CN111774560B (202010726676.4), and microporous ceramic rods are embedded in the LF refined ladle microporous ceramic rod ventilation nozzle pocket brick; the number of the microporous ceramic rods is 10, the microporous ceramic rods are cylindrical and are uniformly distributed in the ladle nozzle pocket brick body in an annular shape, the diameter d of each ceramic rod is 35mm, and the height h of each ceramic rod is 160mm.
After the steel ladle is lifted to a position to be poured of the continuous casting rotary table, communicating an air inlet pipe of the steel ladle air inlet brick cup with an argon gas source pipeline, blowing argon gas into the steel ladle while pouring the steel ladle, wherein the argon gas flow is 25NL/min, adjusting the argon gas flow to 5NL/min after the argon gas blowing time is 20 minutes, and closing the argon gas after the steel ladle is transferred to the position to be poured from the pouring position of the continuous casting rotary table, and disconnecting the air inlet pipe of the steel ladle air inlet brick cup from the argon gas source pipeline.
4) Argon blowing metallurgical technology for tundish upper nozzle pocket brick in the continuous casting and pouring process: in the pouring process of the tundish, an argon blowing structure is arranged at a tapping hole of the tundish for blowing argon, specifically, a continuous casting tundish air-permeable upper nozzle pocket brick with an argon blowing function is adopted to replace the existing tundish upper nozzle pocket brick, the continuous casting tundish air-permeable upper nozzle pocket brick is a continuous casting tundish dispersion-type air-permeable ring upper nozzle pocket brick in the prior art CN106041045B (201610634270.7), and a dispersion-type air-permeable ring is embedded in the continuous casting tundish dispersion-type air-permeable ring upper nozzle pocket brick; the whole diffuse-type ventilation ring is in a circular ring shape, the longitudinal section of the diffuse-type ventilation ring is in a right trapezoid shape, the width x of the upper end of the circular ring is 30mm, the width y of the lower end of the circular ring is 40mm, the height h of the circular ring is 90mm, the diffuse-type ventilation ring is formed by adopting high-purity corundum, mullite and the like as main raw materials in a mechanical pressing mode, and the volume density is more than or equal to 2.6g/cm 3 The high-temperature compressive strength is more than or equal to 50Mpa, the apparent porosity is 25-28%, al 2 O 3 +SiO 2 +Cr 2 O 3 The content is more than or equal to 94 percent.
When the tundish seat ladle is in a baking position, an air inlet pipe of a tundish upper nozzle seat brick is communicated with an argon gas source pipeline, argon is blown in during baking, the argon flow is 5NL/min, when molten steel in the tundish reaches the liquid level of normally poured molten steel, the argon flow is regulated to 12NL/min, after the ladle is closed and stopped pouring, argon is closed, and after the tundish is closed and stopped pouring, the air inlet pipe of the tundish upper nozzle seat brick is disconnected with the argon gas source pipeline.
Comparative example 1: chinese patent document CN109777917a (201910145116.7) discloses a calcium treatment advancing process of a refining furnace, after a calcium treatment process is moved to an LF refining furnace for treatment, a calcium wire is fed into molten steel after the LF refining furnace treatment is completed, the feeding amount is 120 m/furnace, and the process is used for producing steel grade DH36, the thickness of a rolled material is 50mm, and other process steps adopt the prior art.
Examples 1-3 and comparative example 1 were applied to Laiwu iron and Steel group Yinshan section steel Co., ltd. Wide-thickness plate continuous casting machines, respectively, and were subjected to comparative analysis on LF average ton steel refining power consumption, RH average refining time, ladle long nozzle average life, submerged nozzle average life, and metallographic inclusion grade in rolled materials, and comparative results are shown in Table 1.
TABLE 1
By comparing the data in the table 1, the invention shortens the refining time of the RH furnace because the RH furnace cannot be heated, so the tapping temperature of the LF furnace can be correspondingly reduced, compared with the prior art CN109777917A (201910145116.7), the invention reduces the tapping temperature of the LF furnace by 5-12 ℃ in a same ratio, shortens the electrifying time of LF refining by 2-6 minutes in a same ratio, reduces the electricity consumption of LF ton steel refining by more than 4.2kwh in a same ratio, reduces the RH refining time by more than 7.3 minutes in a same ratio, ensures that the average service lives of a ladle long nozzle and a submerged nozzle are both prolonged by more than 2 hours in a same ratio, and B, D inclusions in rolled materials are reduced from 1.0 grade to 0.5 grade.
Claims (8)
1. A molten steel refining method of steel for ocean platforms below EH36 adopts the following process routes: the method comprises the steps of converter smelting, LF furnace refining, RH refining and wide and thick plate continuous casting machine casting and is characterized in that: advancing the calcium treatment from the RH refining furnace to the LF refining furnace to reduce the tapping temperature of the LF refining furnace;
adopting a converter tapping process molten steel pre-refining technology, a continuous casting pouring process ladle gas-permeable upper nozzle pocket brick argon blowing metallurgical technology and a tundish gas-permeable upper nozzle pocket brick argon blowing metallurgical technology to perform multi-procedure argon blowing on molten steel to remove impurities, specifically comprising the following steps:
in the converter smelting stage, a molten steel pre-refining technology in the converter tapping process is adopted: adding premelted refining slag to conduct premelted refining in the converter tapping process, wherein the premelted refining slag contains Al so as to enable the exothermic reaction of metal aluminum and oxygen to compensate the temperature drop of molten steel, and controlling the flow of argon blown from the bottom of a ladle in a sectional manner;
the molten steel pre-refining technology in the converter tapping process specifically comprises the following steps: in the tapping process of the top-bottom combined blown converter, adding 1.5-2.3 kg/t molten steel of premelted refining slag along with steel flow, and after 3 minutes before the end point, blowing argon into the bottom of the steel ladle, wherein the argon flow control is divided into six stages:
the stage 1 is a tapping starting stage, the argon blowing flow is 30-50 NL/min, and the argon blowing time is 50-60 seconds;
the stage 2 is a deoxidizer and alloy adding stage, the argon blowing flow is 150-200 NL/min, and the argon blowing time is 30-50 seconds;
the stage 3 is a slag charge adding stage, the argon blowing flow is 100-150 NL/min, and the argon blowing time is 30-40 seconds;
the stage 4 is an inclusion floating stage, the argon blowing flow is 50-100 NL/min, and the argon blowing time is 40-50 seconds;
the stage 5 is a tapping slag-stopping stage, the argon blowing flow is 30-50 NL/min, and the argon blowing time is 50-60 seconds;
the stage 6 is a stage from the end of tapping to the hanging-away of molten steel, the argon blowing flow is 50-100 NL/min, and the argon blowing time is 50-60 seconds;
the ladle pouring stage adopts the argon blowing metallurgical technology of a ladle ventilation upper nozzle pocket brick during the continuous casting pouring process: in the ladle pouring process, arranging an argon blowing structure at the tapping hole for blowing argon;
the pouring stage of the tundish adopts the argon blowing metallurgical technology of the tundish ventilation upper nozzle pocket brick: in the pouring process of the tundish, an argon blowing structure is arranged at a tapping hole of the tundish to blow argon.
2. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 1, wherein:
1) The argon blowing metallurgical technology of the ladle ventilation upper nozzle pocket brick in the continuous casting and pouring process specifically comprises the following steps: adopting a ladle ventilation upper nozzle pocket brick with an argon blowing function to replace the existing ladle upper nozzle pocket brick, after the ladle is lifted to a position to be poured of a continuous casting rotary table, communicating an air inlet pipe of the ladle ventilation upper nozzle pocket brick with an argon gas source pipeline, blowing argon gas into the ladle while pouring the ladle, adjusting the argon gas flow to be 5-10 NL/min after the argon blowing time is 20-25 minutes, closing the argon gas after the ladle is rotated to the position to be poured from the pouring position of the continuous casting rotary table, and disconnecting the air inlet pipe of the ladle ventilation upper nozzle pocket brick from the argon gas source pipeline;
2) The argon blowing metallurgical technology of the tundish upper nozzle pocket brick in the continuous casting and pouring process specifically comprises the following steps: adopting a continuous casting tundish air-permeable upper nozzle pocket brick with argon blowing function to replace the existing tundish upper nozzle pocket brick, when the tundish pocket is in a baking position, communicating an air inlet pipe of the tundish upper nozzle pocket brick with an argon gas source pipeline, blowing argon gas into the tundish upper nozzle pocket brick while baking, and when molten steel in the tundish reaches the liquid level of normally poured molten steel, regulating the argon gas flow to 12-15 NL/min, closing the nozzle after the ladle is closed and stopped pouring, and disconnecting the air inlet pipe of the tundish upper nozzle pocket brick from the argon gas source pipeline after the tundish is closed and stopped pouring.
3. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 1, wherein: the LF refining furnace adopts high alkalinity and high reducibility top slag, and a rapid desulfurization technology of large-flow stirring: aluminum particles, aluminum slag and calcium carbide are adopted to regulate slag, an aluminum feeding wire is adopted to increase aluminum, and the final slag alkalinity is controlled to be more than 2.2;
the key points of operation control are as follows: stirring the large argon gas entering the station for 1 to 2 minutes, regulating the pressure of the argon gas to 0.8 to 1.5Mpa, regulating the pressure of the argon gas to 0.2 to 0.4Mpa, measuring the temperature and oxygen by adopting a low-oxygen probe, and carrying out aluminum wire feeding operation according to the measured aluminum content and target components; then electrifying to remove slag, and stirring with large argon for 2-3 minutes before sampling 1; carrying out power-on and temperature rise during the component of the sample 1; according to the sample 1, carrying out aluminum preparation operation or not, stirring for 1-2 minutes by large argon before sampling 2, and carrying out fine adjustment on the temperature; feeding wire for calcification, sampling and soft blowing, wherein the refining time is controlled to be 40-50 minutes, and the soft blowing time is controlled to be 5-8 minutes.
4. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 3, wherein: and determining the wire feeding quantity according to the control requirement of the calcium content in refined molten steel, the calcium content in the wire feeding and the yield, and feeding the wire according to 0.50-0.90 m/ton of molten steel with high calcium or 0.75-1.5 m/ton of molten steel with calcium and aluminum wires.
5. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 1, wherein: RH refining adopts a vacuum inclusion removal technology of an RH refining furnace: the low-high-low circulation mode is selected, the vacuum degree is within 133Pa, the time is 15-20 minutes, and the RH ensures that the pure degassing time is more than 5 minutes.
6. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 2, wherein: the ladle air-permeable upper nozzle pocket brick is one of an LF refined ladle microporous ceramic rod air-permeable upper nozzle pocket brick or a ladle dispersion ring air-permeable upper nozzle pocket brick.
7. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 2, wherein: the continuous casting tundish air-permeable upper nozzle pocket brick is one of a continuous casting tundish dispersion air-permeable ring upper nozzle pocket brick or a continuous casting tundish air-permeable ceramic tube upper nozzle pocket brick.
8. The method for refining molten steel for an offshore platform steel having an EH36 or lower as set forth in claim 1, wherein: the premelted refining slag contains CaO 40-50% and Al 2 O 3 The content is 35-40%, al content is 5-7%, siO 2 （%）≤5，Fe 2 O 3 (%) is less than or equal to 1.5, mgO (%) is less than or equal to 2, P and S (%) is less than or equal to 0.02, and water (%) is less than or equal to 1.0.
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