CN114774615B - Method for producing ultralow-sulfur steel by adopting high-sulfur semisteel - Google Patents

Method for producing ultralow-sulfur steel by adopting high-sulfur semisteel Download PDF

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CN114774615B
CN114774615B CN202210450920.8A CN202210450920A CN114774615B CN 114774615 B CN114774615 B CN 114774615B CN 202210450920 A CN202210450920 A CN 202210450920A CN 114774615 B CN114774615 B CN 114774615B
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steel
sulfur
slag
equal
percent
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CN114774615A (en
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胡楚江
王前
王启丞
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Heilongjiang Jianlong Iron and Steel Co Ltd
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Heilongjiang Jianlong Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • 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
    • 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
    • C21C7/076—Use of slags or fluxes as treating agents
    • 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

A method for producing ultralow-sulfur steel by adopting high-sulfur semisteel belongs to the technical field of ferrous metallurgy. The method solves the problems of complex process and high cost existing in the existing method for producing the ultra-low sulfur steel in batches by adopting the high sulfur semisteel. The method comprises the following steps: 1. the steel iron material and the silicon-carbon alloy are put into a converter for smelting; 2. steel ladle deoxidization, alloying and slagging during tapping; 3. sampling and analyzing after LF refining; 4. after the analysis result is qualified, feeding an aluminum wire to adjust Als, and tapping LF; 5. and carrying out VD high vacuum treatment, deep deoxidization and calcium treatment, soft blowing and tapping to obtain the ultralow-sulfur steel with S less than or equal to 0.002%. The invention adopts the high-sulfur semisteel to produce the ultralow-sulfur steel, realizes single slag refining, ensures furnace machine matching and smooth production, creates a precedent for stably producing the ultralow-sulfur steel in batches by utilizing high-sulfur raw and auxiliary materials, has simple process and low cost, and can stably control the sulfur content in the finished product to be below 0.002 percent. The invention is suitable for producing ultralow-sulfur steel from high-sulfur semisteel.

Description

Method for producing ultralow-sulfur steel by adopting high-sulfur semisteel
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a method for producing ultralow-sulfur steel by adopting high-sulfur semisteel.
Background
With the continuous and deep progress of petroleum exploitation, oil fields with better working conditions and low corrosive medium content have been developed and utilized, while the productivity of these high-quality oil fields can not meet the increasing economic development requirement, so as to meet the increasing petroleum demand, the geological structure is complex and corrosive medium H 2 S、CO 2 The exploitation of oil gas with high content, high salt and high alkali is imperative. The exploitation of oil gas with complex working conditions and high content of corrosive medium requires the use of high-strength, high-toughness and corrosion-resistant high-end petroleum pipes, and the high-end petroleum pipes have a common characteristic that the S content in the pipes is required to be controlled in an ultralow content range (S is less than or equal to 0.003 percent, and the S is required to be less than or equal to 0.001 percent or even lower), thus the high-end petroleum pipes belong to ultralow-sulfur steel and ultralow-sulfur steel. The Heilongjiang Jianlong Steel Limited company has a round billet-two rolling pipes-one heat-treated seamless steel pipe complete industrial chain production line, and has the tooling conditions for producing high-end oil and gas pipes. Development of ultra-low sulfur steel batch production process, development of high-strength high-toughness H-resistant steel 2 S, the oil well pipe is corroded, so that the industrial requirements of oil exploitation are met.
The raw material conditions of Heilongjiang Jianlong Steel Co., ltd are: the sulfur content in the high-vanadium molten iron is high and is between 0.040 and 0.070 percent; firstly, extracting vanadium from high vanadium molten iron, wherein in order to ensure the vanadium content in vanadium slag obtained by extracting vanadium, molten iron pretreatment desulfurization cannot be performed, meanwhile, slag materials such as lime and the like cannot be added during vanadium extraction, and the vanadium extraction slag is acid slag and does not have desulfurization capability; in order to ensure the recovery rate of vanadium, the blowing temperature is controlled between 1340 ℃ and 1390 ℃ in a stable way, the thermodynamic conditions of vanadium extraction are poor, the desulfurization rate is extremely low, and the S content of the semisteel obtained after vanadium extraction of molten iron is high and is between 0.04 and 0.07%. To develop high-strength, high-toughness and hydrogen sulfide corrosion-resistant high-end petroleum pipes of ultra-low sulfur steel, a technology for stably producing the ultra-low sulfur steel by using the high-sulfur semisteel is required to be developed, so that the stable batch production of the ultra-low sulfur steel by using the high-sulfur semisteel is realized, and the existing batch production of the ultra-low sulfur steel by using the high-sulfur semisteel also has the problems of complex process and high cost.
Disclosure of Invention
The invention aims to solve the problems of complex process and high cost of the existing batch production of ultra-low sulfur steel by adopting high sulfur semisteel, and provides a method for producing ultra-low sulfur steel by adopting high sulfur semisteel.
A method for producing ultralow-sulfur steel by adopting high-sulfur semisteel comprises the following steps:
1. smelting in a converter according to iron steel materials and silicon-carbon alloy, wherein the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5, the FeO content is controlled to be 15-20%, the carbon content at the end point of the converter is controlled to be 0.05-0.08%, the end point temperature is 1630-1650 ℃, and the desulfurization rate of the converter is controlled to be more than or equal to 30%;
the steel material consists of 94% of high-sulfur semisteel and 6% of low-sulfur scrap steel in percentage by mass, wherein S in the low-sulfur scrap steel is less than or equal to 0.006%; the consumption of the silicon-carbon alloy is 4% of the total mass of the steel material; the silicon-carbon alloy comprises the following components in percentage by weight: c is more than or equal to 2%, si is more than or equal to 45% and the balance of Fe;
2. when tapping in the converter, carrying out ladle deoxidation, alloying and slagging;
the ladle deoxidizes, alloys and slag is formed: adding calcium carbide and half of the total amount of aluminum ingots when tapping to 1/5, adding a carburant, starting to add alloy and the rest aluminum ingots when tapping to 1/3, adding slag materials when tapping to 1/2, adding Als after argon in molten steel is more than or equal to 0.015%, and turning slag on the top of a ladle into white or grey after argon;
3. transferring to an LF refining station after finishing, feeding an aluminum wire to adjust Als in molten steel to 0.020%, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding partial slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of a steel ladle is melted, stopping power when the temperature of the refined slag is more than or equal to 1560 ℃ until the refined slag turns white, forcibly stirring for 2min under the condition that the argon flow is 6-8 NL/min/t steel, then taking a refined slag sample for analysis, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding residual slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of the steel ladle melts, stopping power after the analysis result of the refined slag sample is qualified, adjusting the argon flow to 6-8 NL/min/t steel, supplementing alloy and carburant, regulating the argon flow to 3-4 NL/min/t steel and starting to transmit electricity after 3min, and taking a sample under the condition of 6-8 NL/min/t of forced stirring for 3min, and then taking a sample for analysis;
4. after the sampling analysis result is qualified, the temperature reaches 1660-1710 ℃, aluminum wires are fed to adjust Als in molten steel to 0.035-0.040%, and the LF furnace is tapped;
and (5) the standard for qualified sampling analysis results: the composition by weight percentage is as follows: c:0.10 to 0.35 percent of Si:0.15 to 0.35 percent of Mn:0.40 to 1.60 percent of Cr:0.20 to 1.20 percent of Mo:0.10 to 1.10 percent of Nb: 0.020-0.050%, V:0.03 to 0.12 percent, less than or equal to 0.015 percent of P, less than or equal to 0.002 percent of S, residual impurities and the balance of Fe;
5. and after tapping in the LF furnace, carrying out VD high vacuum treatment, after breaking the VD, feeding a silicon-calcium wire for deep deoxidization and calcium treatment, then carrying out soft blowing, and tapping at 1580-1600 ℃ to obtain ultralow sulfur steel with S less than or equal to 0.002%, thereby completing the method.
The invention adopts the high-sulfur semisteel to produce the ultralow-sulfur steel, realizes single slag refining, ensures the matching and production smooth operation of a furnace machine, creates a precedent for stably producing the ultralow-sulfur steel in batches by utilizing high-sulfur raw and auxiliary materials, and has simple process and low cost. The sulfur content of the semi-steel filled into the converter is 0.04-0.07%, the desulfurization rate of the converter is more than or equal to 30%, the refining desulfurization rate is more than or equal to 95% under the condition of no pretreatment desulfurization, and the sulfur content in the finished product can be stably controlled below 0.002%.
Compared with the existing steelmaking enterprises which adopt molten iron pre-desulfurization, converter smelting, refining and continuous casting processes to produce ultra-low sulfur and ultra-low sulfur steel, the sulfur content in the molten iron pre-desulfurized by the existing converter is less than or equal to 0.006%; the S content of the semi-steel filled into the converter is 0.04-0.07%.
Compared with the method for improving the scrap steel ratio and reducing the iron ratio of the conventional converter (the common scrap steel adding ratio exceeds 20 percent), the steel-iron material of the invention consists of 94 percent of high-sulfur semisteel and 6 percent of low-sulfur scrap steel, wherein S in the low-sulfur scrap steel is less than or equal to 0.006 percent; adding 4% of silicon-carbon alloy into each furnace; so as to ensure that the end temperature of the converter is more than or equal to 1630 ℃ and create temperature conditions for desulfurization of the converter.
Compared with a conventional converter, the method focuses on the desulfurization rate of the converter process, controls the binary basicity of the final slag of the converter to be more than or equal to 4.5, the FeO content to be 15-20%, the carbon content of the final point of the converter to be 0.05-0.08%, the final point temperature to be 1630-1650 ℃ and the desulfurization rate of the converter to be more than or equal to 30%.
Compared with the conventional ladle deoxidization alloying, the method focuses on the full deoxidization of the ladle and the advanced white slag making in the tapping process of the converter, and creates good conditions for LF desulfurization.
Compared with the conventional refining, the invention adopts the method of CaO-MgO-Al 2 O 3 -SiO 2 BaO-CaO-Al with stronger desulfurization capability 2 O 3 -MgO-SiO 2 And the content range of each component is strictly controlled, so that the ladle top slag desulfurization capability of the refining ladle is ensured to be lower, and the sulfur in the steel is removed to be lower.
Compared with the conventional refining slag components, the ladle top slag is added with BaO components, the content of each component is strictly controlled, the distribution coefficient of sulfur among slag steels is improved, the desulfurization capacity of the ladle top slag is improved, a large amount of slag is realized, the desulfurization capacity of the ladle top slag is improved, and the sulfur content in steel is controlled to be lower.
The invention is suitable for producing ultralow-sulfur steel from high-sulfur semisteel.
Detailed Description
The technical scheme of the invention is not limited to the specific embodiments listed below, and also includes any combination of the specific embodiments.
The first embodiment is as follows: the method for producing the ultralow-sulfur steel by adopting the high-sulfur semisteel in the embodiment comprises the following steps of:
1. smelting in a converter according to iron steel materials and silicon-carbon alloy, wherein the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5, the FeO content is controlled to be 15-20%, the carbon content at the end point of the converter is controlled to be 0.05-0.08%, the end point temperature is 1630-1650 ℃, and the desulfurization rate of the converter is controlled to be more than or equal to 30%;
the steel material consists of 94% of high-sulfur semisteel and 6% of low-sulfur scrap steel in percentage by mass, wherein S in the low-sulfur scrap steel is less than or equal to 0.006%; the consumption of the silicon-carbon alloy is 4% of the total mass of the steel material; the silicon-carbon alloy comprises the following components in percentage by weight: c is more than or equal to 2%, si is more than or equal to 45% and the balance of Fe;
2. when tapping in the converter, carrying out ladle deoxidation, alloying and slagging;
the ladle deoxidizes, alloys and slag is formed: adding calcium carbide and half of the total amount of aluminum ingots when tapping to 1/5, adding a carburant, starting to add alloy and the rest aluminum ingots when tapping to 1/3, adding slag materials when tapping to 1/2, adding Als after argon in molten steel is more than or equal to 0.015%, and turning slag on the top of a ladle into white or grey after argon;
3. transferring to an LF refining station after finishing, feeding an aluminum wire to adjust Als in molten steel to 0.020%, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding partial slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of a steel ladle is melted, stopping power when the temperature of the refined slag is more than or equal to 1560 ℃ until the refined slag turns white, forcibly stirring for 2min under the condition that the argon flow is 6-8 NL/min/t steel, then taking a refined slag sample for analysis, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding residual slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of the steel ladle melts, stopping power after the analysis result of the refined slag sample is qualified, adjusting the argon flow to 6-8 NL/min/t steel, supplementing alloy and carburant, regulating the argon flow to 3-4 NL/min/t steel and starting to transmit electricity after 3min, and taking a sample under the condition of 6-8 NL/min/t of forced stirring for 3min, and then taking a sample for analysis;
4. after the sampling analysis result is qualified, the temperature reaches 1660-1710 ℃, aluminum wires are fed to adjust Als in molten steel to 0.035-0.040%, and the LF furnace is tapped;
and (5) the standard for qualified sampling analysis results: the composition by weight percentage is as follows: c:0.10 to 0.35 percent of Si:0.15 to 0.35 percent of Mn:0.40 to 1.60 percent of Cr:0.20 to 1.20 percent of Mo:0.10 to 1.10 percent of Nb: 0.020-0.050%, V:0.03 to 0.12 percent, less than or equal to 0.015 percent of P, less than or equal to 0.002 percent of S, residual impurities and the balance of Fe;
5. and after tapping in the LF furnace, carrying out VD high vacuum treatment, after breaking the VD, feeding a silicon-calcium wire for deep deoxidization and calcium treatment, then carrying out soft blowing, and tapping at 1580-1600 ℃ to obtain ultralow sulfur steel with S less than or equal to 0.002%, thereby completing the method.
In the second embodiment, the aluminum ingot and the calcium carbide are used as deoxidizers.
In the second embodiment, the ladle top slag becomes white or off-white after argon, thereby ensuring good alloy melting, uniform components and good ladle top slag melting, and simultaneously achieving the purpose of slag formation in advance.
In actual production in the third step of the embodiment, under the abnormal state of the argon system such as abnormal ventilation of the air brick, air leakage of the pipeline and the interface valve, the argon is adjusted according to the actual stirring effect, so that good stirring effect is ensured.
In the third step of the embodiment, the addition amount of various slag materials is calculated and controlled according to the total slag amount of the ladle top slag and the percentage content of each component of the ladle top slag.
In the fifth step of the embodiment, after VD is broken, a silicon-calcium wire is added for deep deoxidation and calcium treatment, so that sulfur recovery is avoided, and the sulfur content in the steel is ensured to be controlled within the range required by ultralow-sulfur steel.
The second embodiment is as follows: the first difference between the embodiment and the specific embodiment is that the high-sulfur semisteel in the first step is prepared by extracting vanadium from high-vanadium molten iron, wherein the semisteel contains 0.04-0.07% of sulfur, 3.3-3.6% of C, 0.08-0.12% of P, the balance of Si and Mn and the balance of Fe. Other steps and parameters are the same as in the first embodiment.
And a third specific embodiment: the first difference between the present embodiment and the specific embodiment is that, in the first step, the method for controlling the binary basicity of the final slag of the converter is as follows: the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5 through the addition amount of lime, and the addition amount of lime is calculated according to the following formula: 3.5× (1000×W1×N1+1000×W2×N2+W3×N3) ×60×28× (M1-3.5×N4), wherein W1 represents the amount of semisteel added in tons; n1 represents the mass percentage content of Si in the semisteel; w2 represents the addition amount of scrap steel, and the unit is ton; n2 represents the mass percentage content of Si in the scrap steel; w3 represents the addition amount of the silicon-carbon alloy, and the unit is kg; n3 represents the mass percentage content of Si in the silicon-carbon alloy; m1 represents CaO mass percent content in lime; n4 represents SiO in lime 2 The mass percentage content is as follows. Other steps and parameters are the same as in the third embodiment.
The specific embodiment IV is as follows: the first difference between the present embodiment and the specific embodiment is that the amount of the calcium carbide in the second step: 40kg per oven. Other steps and parameters are the same as in the first embodiment.
Fifth embodiment: the usage amount of the aluminum ingot in the second step is as follows: the carbon content of the end point is less than or equal to 0.05 percent, and the dosage of the aluminum ingot is 1.7kg/t of steel; the carbon content of the end point is less than or equal to 0.06 percent, and the dosage of the aluminum ingot is 1.4kg/t of steel; the carbon content of the end point is less than or equal to 0.07 percent, and the dosage of the aluminum ingot is 1.2kg/t of steel; the carbon content of the end point is more than or equal to 0.08 percent, and the dosage of the aluminum ingot is 1.0kg/t steel. Other steps and parameters are the same as in the first embodiment.
Specific embodiment six: this embodiment, together with the specific embodiment, is the alloy described in step two: and determining the types and the addition amounts of the corresponding alloys according to the content requirements of the alloy components in the steel types. Other steps and parameters are the same as in the first embodiment.
Seventh embodiment: the present embodiment is the same as the specific embodiment, in which the composition of the slag in the second step: lime 2.5kg/t steel, baCO 3 4kg/t steel and 2.5kg/t steel of premelted slag; the feeding speed of the slag is 60kg/s. Other steps and parameters are the same as in the first embodiment.
Eighth embodiment: this embodiment, together with the specific embodiment, is that in step three, the additional alloy and carburant are as described: according to the carbon content of the steel grade, the content requirement of each alloy component and the sampling analysis result, determining the carburant, the corresponding alloy types and the addition amount thereof; the additional alloy and carburant are added to the liquid surface of the steel exposed above the argon port. Other steps and parameters are the same as in the first embodiment.
Detailed description nine: this embodiment, together with the specific embodiment, is a qualification standard of the analysis result of the refining slag sample in the third step: the composition by weight percentage is BaO: 31-37%, caO: 25-30 percent of MgO:5 to 8 percent of Al 2 O 3 ：21～25％、SiO 2 :6 to 10 percent of FeO less than 0.5 percent, and the balance of MnO and TiO 2 . Other steps and parameters are the same as in the first embodiment.
Detailed description ten: the embodiment is the same as the specific embodiment, wherein the total amount of slag in the third step is 25kg/t steel, 65% of the total amount is added for the first time, and the rest amount is added for the second time. Other steps and parameters are the same as in the first embodiment.
Eleventh embodiment: the present embodiment is the same as the specific embodiment, in which the composition of the slag in the third step: lime 2.5kg/t steel, baCO 3 4kg/t steel and premelted slag 2.5kg/t steel. Other steps and parameters are the same as in the first embodiment.
Twelve specific embodiments: the present embodiment is the same as the specific embodiment, in the fifth step, the VD high vacuum treatment: vacuum degree is less than or equal to 67Pa, and degassing time is more than or equal to 15min. Other steps and parameters are the same as in the first embodiment.
Thirteen specific embodiments: this embodiment, together with the specific embodiment, is the deep deoxidizing and calcium treating described in step five: the feeding amount of the steel is 2m/t, the diameter of the silicon-calcium wire is 13mm, the weight of core powder of the silicon-calcium wire is 220g/m, the mass percentage of Si in the core powder is 55-65%, the mass percentage of Ca is 30-33%, and the balance is iron. Other steps and parameters are the same as in the first embodiment.
Fourteen specific embodiments: the present embodiment is the same as the specific embodiment, in the fifth step, the soft blowing is: argon is blown for treatment, the flow is 20-40 NL/min/t steel, and the time is more than or equal to 15min. Other steps and parameters are the same as in the first embodiment.
The beneficial effects of the invention are verified by the following examples:
examples:
a method for producing ultralow-sulfur steel by adopting high-sulfur semisteel comprises the following steps:
1. smelting in a converter according to iron steel materials and silicon-carbon alloy, wherein the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5, the FeO content is controlled to be 15-20%, the carbon content at the end point of the converter is controlled to be 0.05-0.08%, the end point temperature is 1630-1650 ℃, and the desulfurization rate of the converter is controlled to be more than or equal to 30%;
the steel material consists of 94% of high-sulfur semisteel and 6% of low-sulfur scrap steel in percentage by mass, wherein S in the low-sulfur scrap steel is less than or equal to 0.006%; the consumption of the silicon-carbon alloy is 4% of the total mass of the steel material; the silicon-carbon alloy comprises the following components in percentage by weight: c is more than or equal to 2%, si is more than or equal to 45% and the balance of Fe;
2. when tapping in the converter, carrying out ladle deoxidation, alloying and slagging;
the ladle deoxidizes, alloys and slag is formed: adding calcium carbide and half of the total amount of aluminum ingots when tapping to 1/5, adding a carburant, starting to add alloy and the rest aluminum ingots when tapping to 1/3, adding slag materials when tapping to 1/2, adding Als after argon in molten steel is more than or equal to 0.015%, and turning slag on the top of a ladle into white or grey after argon;
3. transferring to an LF refining station after finishing, feeding an aluminum wire to adjust Als in molten steel to 0.020%, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding partial slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of a steel ladle is melted, stopping power when the temperature of the refined slag is more than or equal to 1560 ℃ until the refined slag turns white, forcibly stirring for 2min under the condition that the argon flow is 6-8 NL/min/t steel, then taking a refined slag sample for analysis, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding residual slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of the steel ladle melts, stopping power after the analysis result of the refined slag sample is qualified, adjusting the argon flow to 6-8 NL/min/t steel, supplementing alloy and carburant, regulating the argon flow to 3-4 NL/min/t steel and starting to transmit electricity after 3min, and taking a sample under the condition of 6-8 NL/min/t of forced stirring for 3min, and then taking a sample for analysis;
4. after the sampling analysis result is qualified, the temperature reaches 1660-1710 ℃, aluminum wires are fed to adjust Als in molten steel to 0.035-0.040%, and the LF furnace is tapped;
and (5) the standard for qualified sampling analysis results: the composition by weight percentage is as follows: c:0.10 to 0.35 percent of Si:0.15 to 0.35 percent of Mn:0.40 to 1.60 percent of Cr:0.20 to 1.20 percent of Mo:0.10 to 1.10 percent of Nb: 0.020-0.050%, V:0.03 to 0.12 percent, less than or equal to 0.015 percent of P, less than or equal to 0.002 percent of S, residual impurities and the balance of Fe;
5. and after tapping in the LF furnace, carrying out VD high vacuum treatment, after breaking the VD, feeding a silicon-calcium wire for deep deoxidization and calcium treatment, then carrying out soft blowing, and tapping at 1580-1600 ℃ to obtain ultralow sulfur steel with S less than or equal to 0.002%, thereby completing the method.
In the second embodiment, the aluminum ingot and the calcium carbide are used as deoxidizers.
In the second embodiment, the ladle top slag becomes white or off-white after argon is treated, so that good alloy melting, uniform components and good ladle top slag melting are ensured, and the purpose of slag formation in advance is achieved.
In actual production in step three of this embodiment, under the state that the air brick ventilation is abnormal, pipeline and interface valve have the argon gas system such as gas leakage abnormal, according to actual stirring effect adjustment argon gas, ensure that stirring effect is good.
In the third step of the embodiment, the addition amount of various slag materials is calculated and controlled according to the total slag amount of the ladle top slag and the percentage content of each component of the ladle top slag.
In the fifth step of the embodiment, after VD is broken, a silicon-calcium wire is added for deep deoxidation and calcium treatment, so that sulfur recovery is avoided, and the sulfur content in the steel is ensured to be controlled within the range required by ultralow-sulfur steel.
The high-sulfur semisteel in the step one of the embodiment is prepared by extracting vanadium from high-vanadium molten iron, wherein the sulfur content in the semisteel is 0.04-0.07%, the C content in the semisteel is 3.3-3.6%, the P content is 0.08-0.12%, the Si and Mn are the residual amount, and the balance is Fe.
The method for controlling the binary alkalinity of the final slag of the converter in the step one of the embodiment comprises the following steps: the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5 through the addition amount of lime, and the addition amount of lime is calculated according to the following formula: 3.5× (1000×W1×N1+1000×W2×N2+W3×N3) ×60×28× (M1-3.5×N4), wherein W1 represents the amount of semisteel added in tons; n1 represents the mass percentage content of Si in the semisteel; w2 represents the addition amount of scrap steel, and the unit is ton; n2 represents the mass percentage content of Si in the scrap steel; w3 represents the addition amount of the silicon-carbon alloy, and the unit is kg; n3 represents the mass percentage content of Si in the silicon-carbon alloy; m1 represents CaO mass percent content in lime; n4 represents SiO in lime 2 The mass percentage content is as follows.
The amount of the calcium carbide in the second step of the embodiment: 40kg per oven.
The amount of aluminum ingot used in step two of this example: the carbon content of the end point is less than or equal to 0.05 percent, and the dosage of the aluminum ingot is 1.7kg/t of steel; the carbon content of the end point is less than or equal to 0.06 percent, and the dosage of the aluminum ingot is 1.4kg/t of steel; the carbon content of the end point is less than or equal to 0.07 percent, and the dosage of the aluminum ingot is 1.2kg/t of steel; the carbon content of the end point is more than or equal to 0.08 percent, and the dosage of the aluminum ingot is 1.0kg/t steel.
The alloy in step two of this example: and determining the types and the addition amounts of the corresponding alloys according to the content requirements of the alloy components in the steel types.
Composition of the slag in step two of this embodiment: lime 2.5kg/t steel, baCO 3 4kg/t steel and 2.5kg/t steel of premelted slag; the feeding speed of the slag is 60kg/s.
The additional alloy and carburant described in step three of this example: according to the carbon content of the steel grade, the content requirement of each alloy component and the sampling analysis result, determining the carburant, the corresponding alloy types and the addition amount thereof; the additional alloy and carburant are added to the liquid surface of the steel exposed above the argon port.
Qualification criteria for analysis results of the refinery slag samples described in step three of this example: the composition by weight percentage is BaO: 31-37%, caO: 25-30 percent of MgO:5 to 8 percent of Al 2 O 3 ：21～25％、SiO 2 :6 to 10 percent of FeO less than 0.5 percent, and the balance of MnO and TiO 2 。
The total amount of slag in the third step of the embodiment is 25kg/t steel, 65% of the total amount is added for the first time, and the rest amount is added for the second time.
Composition of the slag in step three of this embodiment: lime 2.5kg/t steel, baCO 3 4kg/t steel and premelted slag 2.5kg/t steel.
In the fifth step of this embodiment, the VD high vacuum treatment: vacuum degree is less than or equal to 67Pa, and degassing time is more than or equal to 15min.
The deep deoxidization and calcium treatment in step five of this example: the feeding amount of the steel is 2m/t, the diameter of the silicon-calcium wire is 13mm, the weight of core powder of the silicon-calcium wire is 220g/m, the mass percentage of Si in the core powder is 55-65%, the mass percentage of Ca is 30-33%, and the balance is iron.
In the fifth step of this embodiment, the soft blowing is performed: argon is blown for treatment, the flow is 20-40 NL/min/t steel, and the time is more than or equal to 15min.
The embodiment adopts the ultra-low sulfur steel produced by the high sulfur semisteel, and the sulfur content in the finished product can be stably controlled below 0.002 percent through detection.

Claims (9)

1. A method for producing ultralow-sulfur steel by adopting high-sulfur semisteel is characterized by comprising the following steps:
1. smelting in a converter according to iron steel materials and silicon-carbon alloy, wherein the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5, the FeO content is controlled to be 15-20%, the carbon content at the end point of the converter is controlled to be 0.05-0.08%, the end point temperature is 1630-1650 ℃, and the desulfurization rate of the converter is controlled to be more than or equal to 30%;
the steel material consists of 94% of high-sulfur semisteel and 6% of low-sulfur scrap steel in percentage by mass, wherein S in the low-sulfur scrap steel is less than or equal to 0.006%; the consumption of the silicon-carbon alloy is 4% of the total mass of the steel material; the silicon-carbon alloy comprises the following components in percentage by weight: c is more than or equal to 2%, si is more than or equal to 45% and the balance of Fe;
2. when tapping in the converter, carrying out ladle deoxidation, alloying and slagging;
the ladle deoxidizes, alloys and slag is formed: adding calcium carbide and half of the total amount of aluminum ingots when tapping to 1/5, adding a carburant, starting to add alloy and the rest aluminum ingots when tapping to 1/3, adding slag materials when tapping to 1/2, adding Als after argon in molten steel is more than or equal to 0.015%, and turning slag on the top of a ladle into white or grey after argon;
3. transferring to an LF refining station after finishing, feeding an aluminum wire to adjust Als in molten steel to 0.020%, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding partial slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of a steel ladle is melted, stopping power when the temperature of the refined slag is more than or equal to 1560 ℃ until the refined slag turns white, forcibly stirring for 2min under the condition that the argon flow is 6-8 NL/min/t steel, then taking a refined slag sample for analysis, starting to transmit electricity under the condition that the argon flow is 3-4 NL/min/t steel, adding residual slag after 1min, adding aluminum particles and calcium carbide to deoxidize white slag after the top slag of the steel ladle melts, stopping power after the analysis result of the refined slag sample is qualified, adjusting the argon flow to 6-8 NL/min/t steel, supplementing alloy and carburant, regulating the argon flow to 3-4 NL/min/t steel and starting to transmit electricity after 3min, and taking a sample under the condition of 6-8 NL/min/t of forced stirring for 3min, and then taking a sample for analysis;
4. after the sampling analysis result is qualified, the temperature reaches 1660-1710 ℃, aluminum wires are fed to adjust Als in molten steel to 0.035-0.040%, and the LF furnace is tapped;
and (5) the standard for qualified sampling analysis results: the composition by weight percentage is as follows: c:0.10 to 0.35 percent of Si:0.15 to 0.35 percent of Mn:0.40 to 1.60 percent of Cr:0.20 to 1.20 percent of Mo:0.10 to 1.10 percent of Nb: 0.020-0.050%, V:0.03 to 0.12 percent, less than or equal to 0.015 percent of P, less than or equal to 0.003 percent of S, residual impurities and the balance of Fe;
5. after tapping in the LF furnace, carrying out VD high vacuum treatment, after VD breaking, feeding a silicon-calcium wire for deep deoxidation and calcium treatment, then carrying out soft blowing, tapping at 1580-1600 ℃ to obtain ultralow sulfur steel with S less than or equal to 0.002%, and thus completing the method;
the high-sulfur semisteel is prepared by extracting vanadium from high-vanadium molten iron, wherein the sulfur content in the semisteel is 0.04-0.07%, the C content in the semisteel is 3.3-3.6%, the P content is 0.08-0.12%, the Si and Mn are the residual quantity, and the balance is Fe.
2. The method for producing ultra-low sulfur steel by using high sulfur semisteel according to claim 1, wherein in the step one, the method for controlling the binary basicity of the converter final slag is as follows: the binary alkalinity of the final slag of the converter is controlled to be more than or equal to 4.5 through the addition amount of lime, and the addition amount of lime is calculated according to the following formula: 3.5× (1000×W1×N1+1000×W2×N2+W3×N3) ×60×28× (M1-3.5×N4), wherein W1 represents the amount of semisteel added in tons; n1 represents the mass percentage content of Si in the semisteel; w2 represents the addition amount of scrap steel, and the unit is ton; n2 represents the mass percentage content of Si in the scrap steel; w3 represents the addition amount of the silicon-carbon alloy, and the unit is kg; n3 represents the mass percentage content of Si in the silicon-carbon alloy; m1 represents CaO mass percent content in lime; n4 represents SiO in lime 2 The mass percentage content is as follows.
3. The method for producing ultra-low sulfur steel by using high sulfur semisteel according to claim 1, wherein the aluminum ingot is used in the second step in an amount of: the carbon content of the end point is less than or equal to 0.05 percent, and the dosage of the aluminum ingot is 1.7kg/t of steel; the carbon content of the end point is less than or equal to 0.06 percent, and the dosage of the aluminum ingot is 1.4kg/t of steel; the carbon content of the end point is less than or equal to 0.07 percent, and the dosage of the aluminum ingot is 1.2kg/t of steel; the carbon content of the end point is more than or equal to 0.08 percent, and the dosage of the aluminum ingot is 1.0kg/t steel.
4. According to claimThe method for producing ultra-low sulfur steel by adopting high sulfur semisteel according to claim 1, wherein the composition of the slag in the second step is as follows: lime 2.5kg/t steel, baCO 3 4kg/t steel and 2.5kg/t steel of premelted slag; the feeding speed of the slag is 60kg/s.
5. A method for producing ultra-low sulfur steel using high sulfur semisteel according to claim 1, wherein in step three, the quality standard of the analysis result of the refined slag sample is: the composition by weight percentage is BaO: 31-37%, caO: 25-30 percent of MgO:5 to 8 percent of Al 2 O 3 ：21～25％、SiO 2 :6 to 10 percent of FeO less than 0.5 percent, and the balance of MnO and TiO 2 。
6. The method for producing ultra-low sulfur steel by using high sulfur semi-steel according to claim 1, wherein the total amount of slag in the third step is 25kg/t steel, 65% of the total amount is added for the first time, and the remaining amount is added for the second time.
7. The method for producing ultra-low sulfur steel using high sulfur semisteel according to claim 1, wherein in the fifth step, the VD high vacuum treatment is performed: vacuum degree is less than or equal to 67Pa, and degassing time is more than or equal to 15min.
8. A method for producing ultra low sulfur steel from high sulfur semisteel according to claim 1, characterized in that in step five said deep deoxidizing and calcium treating: the feeding amount of the steel is 2m/t, the diameter of the silicon-calcium wire is 13mm, the weight of core powder of the silicon-calcium wire is 220g/m, the mass percentage of Si in the core powder is 55-65%, the mass percentage of Ca is 30-33%, and the balance is iron.
9. A method for producing ultra-low sulfur steel using high sulfur semisteel according to claim 1, wherein in step five said soft blowing: argon is blown for treatment, the flow is 20-40 NL/min/t steel, and the time is more than or equal to 15min.
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