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WO2019203278A1 - Procédé de production d'acier liquide - Google Patents

Procédé de production d'acier liquide Download PDF

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Publication number
WO2019203278A1
WO2019203278A1 PCT/JP2019/016502 JP2019016502W WO2019203278A1 WO 2019203278 A1 WO2019203278 A1 WO 2019203278A1 JP 2019016502 W JP2019016502 W JP 2019016502W WO 2019203278 A1 WO2019203278 A1 WO 2019203278A1
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WO
WIPO (PCT)
Prior art keywords
furnace
dri
molten steel
concentration
iron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2019/016502
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English (en)
Japanese (ja)
Inventor
平田　浩
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
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Nippon Steel Corp
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Filing date
Publication date
Application filed by Nippon Steel Corp filed Critical Nippon Steel Corp
Priority to KR1020207029459A priority Critical patent/KR102359738B1/ko
Priority to JP2020514418A priority patent/JP6923075B2/ja
Priority to CN201980023386.9A priority patent/CN112004947B/zh
Publication of WO2019203278A1 publication Critical patent/WO2019203278A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • C21C5/52—Manufacture of steel in electric furnaces
    • 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

Definitions

  • the present invention relates to a method for producing molten steel in which molten iron is produced by reducing and melting reduced iron (DRI) produced by pre-reducing iron oxide (iron ore etc.) in a melting furnace.
  • DRI reduced iron
  • Patent Document 1 a DRI containing 60% or more of metallized iron is produced by the RHF method, and thereafter, molten iron having a carbon content of 1.5 to 4.5% by mass is produced in an arc heating melting furnace, A method is described in which the molten iron is discharged out of the furnace and then desulfurized, dephosphorized and decarburized in another melting furnace. In this method, carbonaceous material is added to the melting furnace in order to reduce the remaining iron oxide content. However, in this method, heat loss is increased by transferring the molten iron to another furnace. Further, when a molten steel is produced by further adding a carbonaceous material to secure a heat source and decarburizing molten iron having a high carbon content, the amount of CO 2 generated is increased. Furthermore, Patent Document 2 discloses a technique for dissolving an iron-based raw material while supplying a hydrocarbon gas. However, this method is costly because it is premised on using hydrocarbon gas.
  • the present invention has high productivity, low heat loss, and low CO 2 generation amount when melting and reducing DRI having a particularly low metallization rate in a melting furnace such as an electric furnace. It aims at providing the manufacturing method of.
  • the present invention in order to produce a molten steel by dissolving and reducing DRI having a low metallization rate, a part of the molten steel is left in the furnace and used as a seed water for the next channel.
  • the seed hot water remains in the molten steel, the dissolution and reduction of DRI is delayed. Therefore, before supplying DRI, only the carbon source is first supplied to the seed hot water to increase the C concentration of the seed hot water.
  • the C concentration is preferably 0.5% by mass or more and 1.5% by mass or less.
  • the present invention is as follows. (1) a first step of obtaining a carbon-containing molten iron by adding a carbon source to the molten steel left in the electric furnace as seed water at the time of steelmaking in the previous ch; A second step in which DRI is added to the carbon-containing molten iron produced in the first step to perform dissolution reduction; Next, a third step of adding a deoxidizer and performing a desulfurization treatment, A fourth step of discharging the desulfurization slag generated by the desulfurization treatment of the third step; Next, a fifth step of performing decarburization processing by blowing oxygen, A sixth step of discharging the decarburized slag generated by the decarburizing process of the fifth step; After discharging the decarburized slag in the sixth step, the seventh step of leaving the seed ch of the next ch and performing steel output; The manufacturing method of the molten steel characterized by having.
  • a method for producing molten steel with high productivity, low heat loss, and low CO 2 generation amount is provided. Can be provided.
  • FIG. 1 is a figure for explaining each process which manufactures molten steel in the embodiment of the present invention.
  • FIG. 2 is a diagram showing the relationship between the C concentration and the melting point of molten iron.
  • FIG. 1 is a view for explaining a method for producing molten steel by melting and reducing DRI having a particularly low metallization rate in a melting furnace such as an electric furnace according to the present embodiment.
  • the manufacturing method according to the present embodiment includes at least seven steps from the first step to the seventh step.
  • the seventh step is a step of discharging the molten steel whose C concentration has been lowered to, for example, less than 0.1% by mass by the decarburization process of the fifth step. At this time, the entire amount of molten steel is not discharged, but the amount of molten steel used as seed water for the next channel is left in the furnace.
  • the seed hot water amount W (t) satisfies the following formula (1). 0.3 ⁇ D 2 ⁇ W ⁇ 1.6 ⁇ D 2 (1)
  • the contact resistance between the DRI and the bottom electrode of the furnace bottom tends to increase, and the arc may not be stabilized.
  • the load of the decarburization process in the 5th process mentioned later will increase that the seed water amount W is 1.6 * D ⁇ 2 > or more.
  • the numerical values “0.3” and “1.6” are values calculated from the product of the bath depth (m) and the density of molten iron (t / m 3 ) in the electric furnace.
  • a coal material such as coal (steam coal) or anthracite is added to the furnace, and the molten steel as the seed hot water is molten iron having a predetermined C concentration.
  • a method of supplying the carbonaceous material there are no particular restrictions on the method of supplying the carbonaceous material, but there is a method of adding free fall from a hopper installed in the upper part of the furnace, a method of supplying the upper electrode from the hollow part as a hollow electrode, and spraying the molten steel using a dedicated lance.
  • a method of directly blowing into molten steel using an immersion lance a method of blowing into molten steel from a bottom blowing tuyer installed for stirring of molten metal, and the like.
  • the DRI added in the second step cannot be melted unless the melting point of iron is exceeded. Therefore, when the C concentration of the seed hot water remains as molten steel such as less than 0.1% by mass, a large amount of energy is required for melting. Further, the operation temperature is equal to or higher than the melting point of iron, and if the superheat is 100 ° C. in order to stabilize the operation, it is necessary to maintain a high temperature state of 1650 ° C. Therefore, the load on the refractory is large.
  • carburization is performed in the first step, and the seed hot water is made a C-containing molten metal.
  • the added metallic iron of DRI is carburized by C in the molten metal, the melting point is lowered, the dissolution rate is accelerated, and the productivity is improved.
  • the operating temperature can be lowered according to the C concentration of the seed hot water, and the load on the refractory is reduced.
  • iron oxide in DRI reacts with C in the seed hot water to promote reduction, the iron oxide concentration in the generated slag is also low.
  • denitrification is promoted with the decarburization reaction in the fifth step, it is possible to reduce nitrogen.
  • the productivity can be improved by using the seed hot water as the C-containing molten metal, and the load on the refractory can be reduced.
  • the C concentration of the molten iron as the seed hot water is preferably 0.5 mass% or more. This is because when the C concentration is less than 0.5% by mass, the carburizing dissolution rate of metallic iron in DRI and the reduction rate of iron oxide are reduced, and the productivity is deteriorated. On the other hand, if the C concentration of the molten iron becomes too high, the decarburization load increases in the fifth step, which will be described later, and the amount of CO 2 generated increases. Therefore, it is preferable that the C concentration of the molten iron which is the seed hot water is 1.5% by mass or less.
  • the DRI manufactured by the shaft furnace or RHF is supplied to the melting furnace, and an arc is generated by applying a voltage between the upper electrode and the lower electrode installed at the bottom of the furnace. And the iron oxide remaining in the DRI is reduced.
  • a method for supplying DRI for example, a lump-like material can be added to the furnace by free fall from a hopper installed at the top, and a powdery material can be used in which the upper electrode is a hollow electrode and blown from the hollow portion.
  • the DRI supplied in the second step has, for example, the composition shown in Table 1 below.
  • a carbon material such as coal or anthracite is added in accordance with the DRI supply rate.
  • the amount of carbon material introduced here is the sum of the amount necessary for carburizing the iron content in the DRI to the C concentration of the molten iron and the amount necessary for reducing the iron oxide (FeO, etc.) in the DRI.
  • Examples of the carbon material input in the second step include general coal and anthracite as in the case of the carbon material input in the first step.
  • Table 2 below shows examples of the composition of steam coal
  • Table 3 shows examples of the composition of anthracite coal.
  • FC in Table 2 and Table 3 represents fixed carbon (Fixed ⁇ ⁇ Carbon), and VM represents a volatile component (Volaile Matter).
  • steam coal and anthracite may be used alone or in combination.
  • carbon sources such as waste plastic and biomass as other carbon materials.
  • the operating temperature is necessary for carburizing the amount of carbon material introduced in the second step and the iron content in the DRI to the C concentration of the molten iron with respect to the C concentration in the molten iron adjusted in the first step. It is determined by the C concentration in the molten iron, which depends on the difference between the amount and the sum required to reduce iron oxide (such as FeO) in the DRI.
  • FIG. 2 is an Fe—C phase diagram showing the change in the melting point of iron with the C concentration. In order to stabilize the operation, it is said that superheat is required to be 100 ° C. or more. For example, in order to operate at superheat 100 ° C., the melting point is 1430 in the case of molten iron having a C concentration of 1.5 mass%.
  • the operating temperature is 1530 ° C.
  • a voltage is applied according to the supply speed of the carbonaceous material and DRI so as to maintain this operating temperature determined by the C concentration in the molten iron.
  • the C concentration of the carbon-containing molten iron before the start of the second step is preferably 0.5% by mass or more and 1.5% by mass or less. It is more preferable to control within the range of 5 mass% or more and 1.5 mass% or less.
  • Iron ore and coal contain sulfur, although the content varies depending on the production area. Since the iron oxide in the DRI is not reduced instantaneously, the iron oxide concentration in the slag is high immediately after the end of the DRI charging. In a state where the iron oxide concentration in the slag is high, the sulfur distribution between the molten iron (hereinafter sometimes referred to as metal) and the slag is low, and more sulfur is present in the metal than in the slag. In the decarburization process of the fifth step described later, sulfur in the metal is difficult to remove.
  • the sulfur concentration of the molten steel after the decarburization process is high, and the low-sulfur steel Not satisfying manufacturing needs.
  • sulfur is a surface active component, it occupies the adsorption site. Therefore, if the sulfur concentration in the metal is high, it is difficult to remove nitrogen from the metal, and the need for low-nitrogen steel production is not satisfied. For this reason, it is important to perform the desulfurization treatment after the second step.
  • a deoxidizer such as metal Al or a metal Al-containing material is added to the furnace to reduce the iron oxide content in the slag, and the oxygen in the molten iron Remove.
  • the sulfur distribution between the slag and the metal becomes high, the sulfur shifts from the metal to the slag, and the sulfur concentration in the metal decreases.
  • the melting furnace is a DC electric furnace
  • the upper electrode is usually a negative electrode and the lower electrode at the bottom of the furnace is a positive electrode.
  • the upper electrode is applied as a positive electrode and the lower electrode at the furnace bottom is applied as a negative electrode, it is electrochemically applied. Apparent sulfur distribution can be increased, and desulfurization can be further promoted.
  • an oxygen lance is inserted into the furnace from the top of the furnace, and oxygen is blown to the molten iron to perform dephosphorization and decarburization, thereby reducing the phosphorus concentration and carbon concentration to a predetermined level.
  • oxygen and carbon in the molten iron react to generate CO gas.
  • nitrogen dissolved in the molten iron is taken into the CO gas, and nitrogen is removed from the molten iron.
  • the sixth step is a step of discharging the decarburized slag generated in the fifth step.
  • phosphorus in the molten iron moves to slag. If decarburization slag is discharged and phosphorus is not discharged out of the system, phosphorus is concentrated and low P steel cannot be manufactured. For this reason, decarburization slag needs to be discharged as much as possible.
  • the first to seventh steps in the present embodiment can produce molten steel with reduced heat loss and reduced CO 2 generation.
  • the first step by adding a carbon source to the seed hot water to obtain molten iron containing carbon, it is possible to increase the dissolution rate and reduction rate of DRI and reduce heat loss.
  • addition of the carbon material for ensuring a heat source can be suppressed, and as a result, the amount of CO 2 generation can also be suppressed.
  • Tables 4 and 5 below show the metal composition and slag composition in each step, respectively.
  • a carbon material such as coal or anthracite is further added in accordance with the DRI supply rate, and the C concentration in the molten iron is 0.1 to 1.5 mass%. It becomes the range. By suppressing the C concentration, the amount of CO 2 generated by the decarburization process can also be suppressed.
  • the conditions in the examples are one condition example adopted to confirm the feasibility and effects of the present invention, and the present invention is based on this one condition example. It is not limited.
  • the present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
  • molten steel was discharged from a DC electric furnace having a furnace diameter of 6 m having a hollow electrode, and 20 t of molten steel was left as seed water in the DC electric furnace.
  • the C concentration of the molten steel produced in the previous ch was 0.05% by mass.
  • carbon material is added from the hollow electrode, and the C concentration of the seed bath is 1.0% by mass while measuring the C concentration with a sub lance probe incorporating a C sensor for measuring the C concentration by thermal analysis. Carburized until.
  • DRI having a metallization rate of 75% was added together with the carbonaceous material, and dissolution reduction was performed.
  • the C concentration in the metal was controlled to remain at 1.0% by mass, and the operation temperature was controlled to 1570 ° C.
  • the dissolution and reduction time was 30 minutes.
  • the amount of molten metal was 300 t, and the amount of slag was 40 t.
  • the third step Al ash was added as a deoxidizer to perform desulfurization. After desulfurization, 30 t of slag was discharged from the exhaust hole of the DC electric furnace in the fourth step. Thereafter, in the fifth step, decarburization treatment was carried out by sending oxygen from an oxygen lance installed in the upper part of the furnace to produce molten steel having a C concentration of 0.05% by mass. In the fifth step, denitrification was promoted together with decarburization, and the produced molten steel had an N concentration of 30 ppm. In the sixth step, the slag generated by the decarburization process was discharged from the exhaust hole. Thereafter, in the seventh step, the molten steel 20 t was left in the furnace as the seed ch for the next ch, and the remaining 280 t of molten steel was produced.
  • a method for producing molten steel with high productivity, low heat loss, and low CO 2 generation amount is provided. It can be provided and has great industrial value.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Manufacture Of Iron (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Abstract

La présente invention comprend : une première étape consistant à obtenir de la fonte liquide contenant du carbone par ajout d'une source de carbone à l'acier liquide laissé dans un four électrique sous forme d'amorce fondue une fois prélevé un enfournement précédent; une deuxième étape consistant à réaliser une réduction par fusion par ajout d'une éponge de fer - DRI - à la fonte liquide contenant du carbone obtenue à la première étape; une troisième étape consistant à réaliser un traitement de désulfuration par ajout d'une matière de désoxydation; une quatrième étape consistant à décharger un laitier de désulfuration obtenu par le traitement de désulfuration à la troisième étape; une cinquième étape consistant à réaliser un traitement de décarburation par insufflation d'oxygène; une sixième étape consistant à décharger le laitier de décarburation obtenu par le traitement de décarburation à la cinquième étape; et une septième étape consistant à prélever de l'acier et à en laisser une partie comme amorce fondue pour un enfournement subséquent, une fois le laitier de décarburation déchargé à la sixième étape.
PCT/JP2019/016502 2018-04-17 2019-04-17 Procédé de production d'acier liquide Ceased WO2019203278A1 (fr)

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KR1020207029459A KR102359738B1 (ko) 2018-04-17 2019-04-17 용강의 제조 방법
JP2020514418A JP6923075B2 (ja) 2018-04-17 2019-04-17 溶鋼の製造方法
CN201980023386.9A CN112004947B (zh) 2018-04-17 2019-04-17 钢液的制造方法

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
WO2021131799A1 (fr) * 2019-12-25 2021-07-01 株式会社神戸製鋼所 Procédé de production d'acier fondu
JP2022189014A (ja) * 2021-06-10 2022-12-22 日本製鉄株式会社 溶鋼の製造方法及びスラグの排滓方法

Families Citing this family (2)

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Publication number Priority date Publication date Assignee Title
JP7211454B2 (ja) * 2021-06-11 2023-01-24 Ｊｆｅスチール株式会社 溶鋼の脱窒方法、脱窒及び脱硫同時処理方法および鋼の製造方法
JP7480751B2 (ja) 2021-06-11 2024-05-10 Ｊｆｅスチール株式会社 溶鋼の脱窒方法および鋼の製造方法

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Publication number Priority date Publication date Assignee Title
WO2021131799A1 (fr) * 2019-12-25 2021-07-01 株式会社神戸製鋼所 Procédé de production d'acier fondu
JP2021102798A (ja) * 2019-12-25 2021-07-15 株式会社神戸製鋼所 溶鋼の製造方法
JP7094264B2 (ja) 2019-12-25 2022-07-01 株式会社神戸製鋼所 溶鋼の製造方法
CN114829635A (zh) * 2019-12-25 2022-07-29 株式会社神户制钢所 钢水的制造方法
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CN114829635B (zh) * 2019-12-25 2023-04-21 株式会社神户制钢所 钢水的制造方法
US12276002B2 (en) * 2019-12-25 2025-04-15 Kobe Steel, Ltd. Molten steel production method
JP2022189014A (ja) * 2021-06-10 2022-12-22 日本製鉄株式会社 溶鋼の製造方法及びスラグの排滓方法
JP7667423B2 (ja) 2021-06-10 2025-04-23 日本製鉄株式会社 溶鋼の製造方法及びスラグの排滓方法

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JPWO2019203278A1 (ja) 2021-02-12
TW201943856A (zh) 2019-11-16
JP6923075B2 (ja) 2021-08-18
KR20200130858A (ko) 2020-11-20
CN112004947B (zh) 2024-03-26
KR102359738B1 (ko) 2022-02-09
TWI698532B (zh) 2020-07-11
CN112004947A (zh) 2020-11-27

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