WO2017119392A1 - Molten iron dephosphorizing agent, refining agent, and dephosphorization method - Google Patents

Molten iron dephosphorizing agent, refining agent, and dephosphorization method Download PDF

Info

Publication number
WO2017119392A1
WO2017119392A1 PCT/JP2016/089082 JP2016089082W WO2017119392A1 WO 2017119392 A1 WO2017119392 A1 WO 2017119392A1 JP 2016089082 W JP2016089082 W JP 2016089082W WO 2017119392 A1 WO2017119392 A1 WO 2017119392A1
Authority
WO
WIPO (PCT)
Prior art keywords
mass
dephosphorization
cao
sio
converter
Prior art date
Application number
PCT/JP2016/089082
Other languages
French (fr)
Japanese (ja)
Inventor
昌平 柿本
祐志 野崎
義明 権田
明人 清▲瀬▼
直樹 古河
Original Assignee
新日鐵住金株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Priority to JP2017560372A priority Critical patent/JP6481774B2/en
Priority to KR1020187002603A priority patent/KR102105353B1/en
Priority to CN201680045089.0A priority patent/CN107849625A/en
Publication of WO2017119392A1 publication Critical patent/WO2017119392A1/en

Links

Images

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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or 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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C21C1/025—Agents used for dephosphorising or 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
    • 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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C21C7/0645—Agents used for dephosphorising or desulfurising
    • 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 hot metal dephosphorization method using a top-bottom converter, which can efficiently produce low phosphorus steel even in a refining process with a short blowing time,
  • the present invention relates to an agent and a dephosphorization method.
  • hot metal dephosphorization is widely performed by a method in which the hot metal is treated under low temperature conditions in a hot metal stage, which is thermodynamically advantageous.
  • a top-bottom converter is suitable for hot metal dephosphorization. This is because, as an oxidant necessary for dephosphorization, gaseous oxygen with less heat loss than a solid oxidation source can be blown from the top blowing lance to the hot metal at high speed.
  • Patent Documents 1 and 2 are known in which a refining agent containing calcium ferrite is added to the hot metal charged in the top-bottom blow converter.
  • Calcium ferrite is a dephosphorization agent composed of a compound of CaO and Fe 2 O 3 and has a higher dissolution rate in dephosphorization slag as compared with quick lime generally used as a dephosphorization agent in hot metal dephosphorization process. Dephosphorization reaction can be promoted.
  • Patent Document 3 discloses a dephosphorizing agent to which Na 2 O is added in order to improve the meltability of calcium ferrite.
  • Patent Document 4 discloses a hatching accelerator in which any one of alumina powder, iron oxide powder, soda ash, and soda glass powder is contained in a refining flux containing 50% by weight or more of quicklime powder.
  • JP 2013-163844 A JP2013-064167A JP 2012-12680 A JP 2001-348610 A
  • the normal calcium ferrite used in the dephosphorization treatment disclosed in Patent Documents 1 and 2 has a liquidus temperature of about 1400 ° C., which is higher than 1200 to 1350 ° C., which is the temperature of the hot metal in the converter. high. This is because solid calcium ferrite dissolves in the dephosphorization slag of the liquid generated by the oxidation reaction of oxygen and Si or Fe in the hot metal supplied from the top blowing lance. It is conceivable that the ferrite is not sufficiently melted, dephosphorization becomes insufficient, and the blowing is completed in a state where [P] (mass% of P dissolved in the steel) does not reach the target value.
  • the blowing time is about 10 minutes, and after 35% of the total blowing time has elapsed, calcium ferrite starts to be added, and the addition is completed until 80% of the total blowing time has elapsed.
  • the technology to do is described. However, for example, when blowing in a short time of 4 minutes or less, there is a concern that the method of Patent Document 2 may cause insufficient melting of calcium ferrite and deteriorate the dephosphorization efficiency.
  • Patent Document 3 describes calcium ferrite containing Na 2 O, but does not describe a dephosphorization method using the same, and a dephosphorization method suitable for a short blowing time is unknown. is there. Further, according to experiments using the top-bottom blow converter of the present inventors, when the dephosphorization agent described in Patent Document 3 is used for a short time of about 4 minutes, calcium ferrite is not sufficient. It did not melt, the phosphorus removal efficiency was insufficient, and it was difficult to produce low phosphorus steel with [P] ⁇ 0.02%.
  • the refining flux mainly composed of quick lime powder is not sufficiently dissolved in a short time of about 4 minutes, and the dephosphorization efficiency is insufficient. This is because quick lime, alumina, iron oxide, and the like contained in the refining flux each have a high melting point and a low melting rate of the entire refining flux.
  • the present inventors have intensively studied, and by adding Al 2 O 3 to calcium ferrite and further optimizing these concentrations, the refining agent can be sufficiently dissolved even in a short time of blowing. And found that low phosphorus steel can be efficiently produced. Further, in addition to Al 2 O 3 , further studies were made to contain SiO 2 and Na 2 O.
  • the following invention was devised.
  • the molten iron dephosphorizing agent according to (1) which contains 1 to 10% by mass of SiO 2 and has a ratio of (SiO 2 % by mass) / (CaO mass%) of 0.04 to 0.3.
  • Further (Na 2 O wt%) / (Al 2 O 3 wt%) ratio contains Na 2 O of from 0.1 to 2.0 as described in any one of (1) or (2) Molten iron dephosphorizer.
  • a refining agent comprising the dephosphorizing agent according to any one of (1) to (3).
  • (5) (4) The refining agent described in (4) is added to the converter to perform dephosphorization of the hot metal, and the charging (CaO) / (SiO 2 ) ratio is 1.3 to 2.0. Dephosphorization method for molten iron.
  • (6) The hot metal dephosphorization method according to (5), wherein the CaO mass contained in the calcium ferrite is 20% or more of the CaO mass contained in the scouring agent.
  • the hot metal dephosphorization method according to (5) wherein the refining agent is charged into the converter before the hot metal is charged.
  • the calcium ferrite in the present invention a compound mainly containing CaO and Fe 2 O 3, 6 in the ratio weight ratio of CaO and Fe 2 O 3: 4 ⁇ 3 : a 7, CaO
  • the sum of mass% and Fe 2 O 3 mass% refers to 70 mass% or more.
  • Calcium ferrite is produced, for example, using quick lime and iron ore as raw materials, and a mixture of these is completely melted in a melting furnace, and after cooling, it is ground into a lump of about 1 to 50 mm.
  • low phosphorus steel refers to steel whose [P] at the slab stage is 0.02% or less, and efficient means that dissolved calcium ferrite sufficiently contributes to dephosphorization.
  • short-time blowing refers to blowing with a blowing time of about 2 to 6 minutes.
  • the present inventors added various compounds to CaO and Fe 2 O 3 in order to improve the meltability of calcium ferrite in the dephosphorization process of the top-bottom blown converter, and various calcium ferrites that were completely melted in a melting furnace. It was created. Also, CaO and Fe 2 O 3 and / or Al 2 O 3 were mixed and formed into a pellet at normal temperature (hereinafter referred to as pellet). Next, using a high-temperature microscope equipped with an infrared gold image furnace, the calcium ferrite and pellets were heated at a rate of temperature increase of 200 ° C./min, and the melting start temperature and the melting end temperature were measured.
  • CFA calcium ferrite composed of CaO, Fe 2 O 3 and Al 2 O 3
  • CF calcium ferrite composed of ordinary CaO and Fe 2 O 3
  • the liquidus temperature of CFA is estimated to be 1350 ° C or less from the melting end temperature and is lower than the liquidus temperature of CF (about 1400 ° C).
  • the use of CFA and the use of CF were considered to increase the dissolution rate and promote dephosphorization.
  • Al 2 O 3 increases the viscosity of the converter slag, if the Al 2 O 3 concentration in the converter slag becomes too high, rapid slag forming occurs in the converter, and slag is generated from the converter furnace port.
  • the frequency of splattering increases, and blowing must be interrupted.
  • the present inventors thus situation investigated proper concentration of Al 2 O 3 to prevent such, by the Al 2 O 3 calcium ferrite and 20% by mass or less to suppress the frequency of slopping, I found that I could operate without interrupting blowing.
  • the Al 2 O 3 concentration is too low, the dissolution rate of calcium ferrite is small, and it is difficult to produce low phosphorus steel by short-time blowing, so the Al 2 O 3 concentration is 2% by mass or more. It was. Furthermore, the present inventors have confirmed that a higher effect can be exhibited by setting the Al 2 O 3 concentration to 4 to 12% by mass.
  • the dissolution rate of calcium ferrite increases by increasing the Al 2 O 3 concentration in calcium ferrite, the CaO concentration in calcium ferrite necessary for dephosphorization becomes relatively low.
  • the present inventors have intensively studied and found that low phosphorus steel can be produced by setting the (Al 2 O 3 mass%) / (CaO mass%) ratio to 0.04 to 0.5. confirmed. When the (Al 2 O 3 mass%) / (CaO mass%) ratio is less than 0.04, the dissolution rate of calcium ferrite is low and dephosphorization is insufficient.
  • the present inventors conducted a test using a high-temperature microscope equipped with the above-described infrared gold image furnace, and obtained calcium ferrite containing CaO, Fe 2 O 3 , Al 2 O 3 and Na 2 O (hereinafter referred to as CFAN). Revealed that the melting start temperature and the melting end temperature are lower than those of CFA. This is presumably because Na 2 O has the effect of lowering the liquidus temperature and solidus temperature of CFA, and the liquidus temperature of CFAN was estimated to be 1330 ° C. or less from the melting end temperature.
  • the present inventors conducted an experiment using a high-temperature microscope equipped with the above-described infrared gold image furnace, and obtained calcium ferrite composed of CaO, Fe 2 O 3 , Al 2 O 3 and SiO 2 (hereinafter referred to as CFAS).
  • the melting start temperature and the melting end temperature are lower than those of CF. This was considered because SiO 2 had the effect of lowering the liquidus temperature and solidus temperature of CF.
  • SiO 2 reduces the basicity of converter slag, if the SiO 2 concentration of converter slag becomes too high, the progress of the dephosphorization reaction is suppressed, and the target [P] level at the end of blowing Can not be satisfied.
  • the present inventors investigated an appropriate SiO 2 concentration for preventing such a situation, and confirmed that the target [P] level was satisfied by making SiO 2 in calcium ferrite 10 mass% or less. .
  • the SiO 2 concentration is too low, the effect to lower the melting temperature could not be confirmed, and the SiO 2 concentration of 1% by mass or more. Furthermore, the present inventors have confirmed that a higher effect can be exhibited by setting the SiO 2 concentration to 2 to 5% by mass.
  • the present inventors diligently studied about the proper composition of SiO 2 and CaO in CFAS, and by setting the ratio of (SiO 2 mass%) / (CaO mass%) to 0.04 to 0.3, low It was confirmed that phosphorus steel could be melted. When the (SiO 2 mass%) / (CaO mass%) ratio is less than 0.04, the dissolution rate of calcium ferrite is low and dephosphorization is insufficient. If the (SiO 2 mass%) / (CaO mass%) ratio is greater than 0.3, the CaO concentration is too low and the dephosphorization is worsened. In addition, the present inventors have confirmed that by controlling the (SiO 2 mass%) / (CaO mass%) ratio to 0.1 to 0.3, a higher effect is exhibited and further dephosphorization is promoted. did.
  • the present inventors conducted an experiment using a high-temperature microscope equipped with the above-described infrared gold image furnace, and obtained calcium ferrite containing CaO, Fe 2 O 3 , Al 2 O 3 , SiO 2 and Na 2 O (hereinafter referred to as CFASN). ) Revealed that the melting start temperature and the melting end temperature were even lower than CFAS. This was thought to be because Na 2 O had the effect of lowering the liquidus temperature and solidus temperature of CFAS.
  • Examples of the Al 2 O 3 source for producing CFA include aluminum ash, alumina-based refractories, and steelmaking slag containing Al 2 O 3.
  • Examples of the SiO 2 source for producing CFAS include peridotite, pumice, SiO 2 There are steelmaking slag including 2 .
  • Examples of Na 2 O sources for CFAN and CFASN include Na 2 CO 3 , soda lime glass, and sodium metasilicate.
  • the refining agent in the dephosphorization treatment in the top-bottom blowing converter, by using calcium ferrite containing Al 2 O 3 at an appropriate concentration, the refining agent is sufficiently dissolved even in a short time of blowing. It is possible to melt low phosphorus steel efficiently. Furthermore, dephosphorization can be further promoted by adding an appropriate amount of Na 2 O and / or SiO 2 in addition to Al 2 O 3 .
  • the scrap 2 is charged into the converter 1.
  • a refining agent 3 containing at least one of CFA, CFAN, CFAS, and CFASN, which are dephosphorizing agents according to the present invention is charged into the furnace.
  • CFA, CFAN, CFAS, and CCASN may have a particle size of about 1 to 50 mm, preferably about 5 to 35 mm.
  • the charging basicity of the converter slag when using CFA, CFAN, CFAS, CFASN is preferably 1.3 to 2.0.
  • the charge basicity refers to “the total amount of CaO contained in the auxiliary raw material supplied into the converter” as a molecule, and “the total amount of SiO 2 contained in the auxiliary raw material supplied into the converter” and “ Si contained in the molten iron and scrap is a number of the ratio is calculated the sum of the SiO 2 mass "in the case of the oxidized to the total SiO 2 as a denominator.
  • the amount of CaO supplied from calcium ferrite is 20% or more of the total CaO mass contained in the refining agent 3 supplied into the converter. Is preferred.
  • the hot metal 4 is charged into the furnace (FIG. 1 (b)), and then blown by blowing oxygen from the lance 5 into the hot metal 4 (FIG. 1 (c)). ).
  • Blowing causes phosphorus in hot metal 3 to react with oxygen and CaO in slag and shift to the slag side.
  • quick lime as a CaO source has a high melting point, and the dissolution rate at the hot metal temperature during refining is small.
  • the dephosphorization agents CFA, CFAN, CFAS, and CFASN according to the present invention melt at the hot metal temperature, so the dissolution rate. Therefore, dephosphorization of hot metal can be promoted by increasing the CaO concentration in the slag early.
  • the charging of the refining agent 3 containing any one of CFA, CFAN, CFAS, and CCASN is effective even after the hot metal 4 is charged in the converter, but the refining agent is charged before the hot metal 4 is charged.
  • 3 is preferably charged. This is to promote dissolution of CFA, CFAN, CFAS, and CFASN by utilizing the stirring force when the molten iron 4 is charged.
  • only CFA, CFAN, CFAS, and CCASN among the refining agents may be charged before the molten iron 4 is charged, and other materials of the refining agent may be charged at the time of blowing.
  • Calcium ferrite composed of CaO and Fe 2 O 3 is a compound that has improved the melting property of CaO as described above, and it is well known that it melts easily against quicklime and exhibits a dephosphorization effect.
  • Al 2 O 3 which is such a dephosphorizing agent or calcium ferrite containing SiO 2 or Na 2 O, the melting point is further lowered, and the dephosphorizing effect can be enhanced.
  • the decarburization is performed in another furnace after dephosphorization, and the converter is tilted after dephosphorization, which is called MURC (Multi-Refining Converter) method.
  • MURC Multi-Refining Converter
  • the blowing time during dephosphorization is usually as short as 4 minutes, and even in such a case, the dephosphorizing agent according to the present invention is used. According to the dephosphorization method, the dephosphorization process can be performed efficiently.
  • dephosphorization treatment in a converter was performed.
  • the conditions for the dephosphorization treatment are as follows: [P] before dephosphorization is 0.1%, blowing time is 3 to 4 minutes, charging basicity is 1.8, and the amount of calcium ferrite used is 10 kg / t.
  • the product [P] in the table is [P] at the slab stage.
  • the charging timing is the timing at which calcium ferrite is charged into the converter, and is “before hot metal charging” or “after hot metal charging”.
  • 1-No. 9 achieved the product [P] ⁇ 0.02%.
  • No. 9 was a product [P] ⁇ 0.015%, and it was found that it showed a better dephosphorization ability.
  • No. which is a comparative example In all of 10 to 16, the product [P]> 0.02%, and dephosphorization was insufficient.
  • no. No. 10 has an Al 2 O 3 content of less than 2% by mass, and dissolution of calcium ferrite was insufficient. No. No. No.
  • No. which is a dephosphorizing agent according to the present invention. 6 and no. 7 has a ratio of Al 2 O 3 of 2 to 20% by mass, (Al 2 O 3 % by mass) / (CaO mass%) of 0.04 to 0.5, SiO 2 of 1 to 10% by mass, (SiO 2 (Mass%) / (CaO mass%) ratio is 0.04 to 0.3, the melting of calcium ferrite is promoted by Al 2 O 3 and SiO 2, and the rate of supplying CaO to the dephosphorized slag is high. It seems that dephosphorization was promoted. On the other hand, no. In No.
  • No. No. 16 has an Al 2 O 3 concentration of less than 2% by mass and SiO 2 of 10% by mass or more, and it is considered that dephosphorization was insufficient because the basicity of slag was lowered by SiO 2 .
  • the present invention can be applied to a dephosphorization processing method in which steel-containing scrap and molten iron are charged into a smelting furnace and blown in a steelmaking process to melt the molten steel.

Landscapes

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

Abstract

A molten iron dephosphorizing agent containing 2-20 mass% Al2O3, the balance being calcium ferrite and impurities and the (Al2O3 mass%)/(CaO mass%) ratio being 0.04-0.5. Dephosphorization of molten iron is performed by adding a refining agent comprising said dephosphorizing agent into a converter furnace.

Description

溶鉄の脱りん剤、精錬剤および脱りん方法Molten iron dephosphorizing agent, refining agent and dephosphorizing method
　本発明は、上底吹き転炉を用いて行う溶銑の脱りん処理方法に関して、吹錬時間が短い精錬工程でも効率的に低りん鋼を溶製できることを特徴とする溶鉄の脱りん剤、精錬剤および脱りん方法に関するものである。 The present invention relates to a hot metal dephosphorization method using a top-bottom converter, which can efficiently produce low phosphorus steel even in a refining process with a short blowing time, The present invention relates to an agent and a dephosphorization method.
　近年、鋼材に対する要求が高度化し、低りん鋼に対する需要が増加している。現在、溶銑の脱りん処理は、熱力学的に有利な溶銑段階の低温条件において処理する方法によって、広く一般に行われている。溶銑脱りんの装置としては上底吹き転炉が適している。それは、脱りんに必要な酸化剤として、固体酸化源に比べて熱ロスの少ない気体酸素を、上吹きランスから高速で溶銑に吹きつけることが可能なためである。 In recent years, the demand for steel materials has increased, and the demand for low phosphorus steel has increased. At present, hot metal dephosphorization is widely performed by a method in which the hot metal is treated under low temperature conditions in a hot metal stage, which is thermodynamically advantageous. A top-bottom converter is suitable for hot metal dephosphorization. This is because, as an oxidant necessary for dephosphorization, gaseous oxygen with less heat loss than a solid oxidation source can be blown from the top blowing lance to the hot metal at high speed.
　溶銑脱りんは、溶銑段階の低温条件において行われるため、脱りん剤として使用されるＣａＯの滓化を促進させることが重要である。ＣａＯの滓化には蛍石（ＣａＦ２）の使用が効果的であるが、蛍石を使用した場合にはＣａＯの滓化により発生したスラグがフッ素を含有するため、スラグの再利用先が大幅に制限されるなどの弊害が大きい。そのため、蛍石を用いないＣａＯ滓化促進法が開発されてきた。 Since hot metal dephosphorization is performed under low temperature conditions in the hot metal stage, it is important to promote the hatching of CaO used as a dephosphorizing agent. The use of fluorite (CaF 2 ) is effective for the hatching of CaO. However, when fluorite is used, the slag generated by the hatching of CaO contains fluorine. Detrimental effects such as significant restrictions are significant. Therefore, CaO hatching promotion methods that do not use fluorite have been developed.
　その方法として、例えば上底吹き転炉に装入された溶銑にカルシウムフェライトを含む精錬剤を添加する特許文献１、２の方法が知られている。カルシウムフェライトは、ＣａＯとＦｅ２Ｏ３の化合物からなる脱りん剤であり、溶銑脱りんプロセスの脱りん剤として一般的に用いられる生石灰と比較して、脱りんスラグへの溶解速度が高く、脱りん反応を促進することができる。また、特許文献３には、カルシウムフェライトの溶融性を改善するためにＮａ２Ｏを加えた脱りん剤について開示されている。また、特許文献４には、生石灰粉を５０重量％以上含む精錬用フラックスにアルミナ粉、酸化鉄粉、ソーダ灰、ソーダガラス粉末のいずれかを含有させた滓化促進剤が開示されている。 For example, Patent Documents 1 and 2 are known in which a refining agent containing calcium ferrite is added to the hot metal charged in the top-bottom blow converter. Calcium ferrite is a dephosphorization agent composed of a compound of CaO and Fe 2 O 3 and has a higher dissolution rate in dephosphorization slag as compared with quick lime generally used as a dephosphorization agent in hot metal dephosphorization process. Dephosphorization reaction can be promoted. Patent Document 3 discloses a dephosphorizing agent to which Na 2 O is added in order to improve the meltability of calcium ferrite. Patent Document 4 discloses a hatching accelerator in which any one of alumina powder, iron oxide powder, soda ash, and soda glass powder is contained in a refining flux containing 50% by weight or more of quicklime powder.
特開２０１３－１６３８４４号公報JP 2013-163844 A 特開２０１３－０６４１６７号公報JP2013-064167A 特開２０１２－１２６８０号公報JP 2012-12680 A 特開２００１－３４８６１０号公報JP 2001-348610 A
　しかしながら、特許文献１、２等に開示された脱りん処理に用いられる通常のカルシウムフェライトは、液相線温度が約１４００℃であり、転炉内の溶銑の温度である１２００～１３５０℃よりも高い。これは上吹きランスから供給される酸素と溶銑中のＳｉやＦｅの酸化反応によって生成する液体の脱りんスラグに、固体のカルシウムフェライトが溶解することになり、吹錬時間が短い場合は、カルシウムフェライトが十分に溶融せず、脱りんが不十分となり、［Ｐ］（鋼中に溶存するＰの質量％）が目標値に到達しない状態で吹錬が終了してしまうことが考えられる。 However, the normal calcium ferrite used in the dephosphorization treatment disclosed in Patent Documents 1 and 2 has a liquidus temperature of about 1400 ° C., which is higher than 1200 to 1350 ° C., which is the temperature of the hot metal in the converter. high. This is because solid calcium ferrite dissolves in the dephosphorization slag of the liquid generated by the oxidation reaction of oxygen and Si or Fe in the hot metal supplied from the top blowing lance. It is conceivable that the ferrite is not sufficiently melted, dephosphorization becomes insufficient, and the blowing is completed in a state where [P] (mass% of P dissolved in the steel) does not reach the target value.
　また、特許文献２には、吹錬時間を１０分間程度とし、全吹錬時間の３５％が経過した後にカルシウムフェライトを添加し始め、全吹錬時間の８０％が経過するまでに添加を完了する技術が記載されている。ところが、例えば４分以内の短時間で吹錬を行う場合、特許文献２の方法では、カルシウムフェライトの溶融が不十分で、脱りん効率が悪化することが懸念される。 In Patent Document 2, the blowing time is about 10 minutes, and after 35% of the total blowing time has elapsed, calcium ferrite starts to be added, and the addition is completed until 80% of the total blowing time has elapsed. The technology to do is described. However, for example, when blowing in a short time of 4 minutes or less, there is a concern that the method of Patent Document 2 may cause insufficient melting of calcium ferrite and deteriorate the dephosphorization efficiency.
　特許文献３には、Ｎａ２Ｏを含有したカルシウムフェライトについて記載されているが、それを用いた脱りん方法について記載されておらず、吹錬時間が短い場合に適した脱りん方法は不明である。また、本発明者らの上底吹き転炉を用いた実験によると、特許文献３に記載の脱りん剤を用いて４分程度の短時間で吹錬を行った場合、カルシウムフェライトは十分に溶解せず、脱りん効率も不十分であり、［Ｐ］＜０．０２％の低りん鋼の溶製が困難であった。 Patent Document 3 describes calcium ferrite containing Na 2 O, but does not describe a dephosphorization method using the same, and a dephosphorization method suitable for a short blowing time is unknown. is there. Further, according to experiments using the top-bottom blow converter of the present inventors, when the dephosphorization agent described in Patent Document 3 is used for a short time of about 4 minutes, calcium ferrite is not sufficient. It did not melt, the phosphorus removal efficiency was insufficient, and it was difficult to produce low phosphorus steel with [P] <0.02%.
　また、特許文献４のように、生石灰粉を主成分とする精錬用フラックスも４分程度の短時間では十分に溶解せず、脱りん効率も不十分である。これは、精錬用フラックスに含まれる生石灰、アルミナ、酸化鉄等は、各々の融点が高く、精錬フラックス全体の溶融速度が小さいためである。 Further, as in Patent Document 4, the refining flux mainly composed of quick lime powder is not sufficiently dissolved in a short time of about 4 minutes, and the dephosphorization efficiency is insufficient. This is because quick lime, alumina, iron oxide, and the like contained in the refining flux each have a high melting point and a low melting rate of the entire refining flux.
　近年、転炉の生産効率を向上するため、溶銑脱りんプロセスの短時間化が図られており、例えば、４分程度の脱りん吹錬時間で［Ｐ］＜０．０２％の低りん鋼を溶製することを要求される。このような背景の中、短時間の吹錬を行った場合においても、低りん鋼の溶製が可能な脱りん剤および脱りん方法の開発が望まれた。 Recently, in order to improve the production efficiency of converters, the hot metal dephosphorization process has been shortened. For example, [P] <0.02% low phosphorus steel with a dephosphorization blowing time of about 4 minutes. Is required to melt. In such a background, it has been desired to develop a dephosphorization method and a dephosphorization method capable of melting low phosphorus steel even when short-time blowing is performed.
　上記課題を解決するため、本発明者らは鋭意検討し、カルシウムフェライトにＡｌ２Ｏ３を含有させ、さらにこれらの濃度を適正化することで、短時間の吹錬でも十分に精錬剤が溶解し、効率的に低りん鋼を溶製できることを見出した。また、Ａｌ２Ｏ３に加え、さらに、ＳｉＯ２、Ｎａ２Ｏを含有させることについても検討を行った。 In order to solve the above problems, the present inventors have intensively studied, and by adding Al 2 O 3 to calcium ferrite and further optimizing these concentrations, the refining agent can be sufficiently dissolved even in a short time of blowing. And found that low phosphorus steel can be efficiently produced. Further, in addition to Al 2 O 3 , further studies were made to contain SiO 2 and Na 2 O.
　その結果、次の発明を考案した。
（１）
　２～２０質量％のＡｌ２Ｏ３を含有し、残部がカルシウムフェライトと不純物であり、
　（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．０４～０．５である、溶鉄の脱りん剤。
（２）
　さらに、１～１０質量％のＳｉＯ２を含有し、（ＳｉＯ２質量％）／（ＣａＯ質量％）比が０．０４～０．３である、（１）に記載の溶鉄の脱りん剤
（３）
　さらに（Ｎａ２Ｏ質量％）／（Ａｌ２Ｏ３質量％）比が０．１～２．０となるＮａ２Ｏを含有する、（１）または（２）のいずれか１項に記載の溶鉄の脱りん剤。
（４）
　（１）～（３）のいずれか１項に記載の脱りん剤を含有する、精錬剤。
（５）
　（４）に記載の精錬剤を転炉内に添加し、溶銑の脱りん処理を行う方法であって、装入（ＣａＯ）／（ＳｉＯ２）比が１．３～２．０である、溶鉄の脱りん方法。
（６）
　前記カルシウムフェライトに含まれるＣａＯ質量が、前記精練剤に含まれるＣａＯ質量の２０％以上である、（５）に記載の溶銑の脱りん方法。
（７）
　前記精錬剤を溶銑の装入よりも前に前記転炉内に投入する、（５）に記載の溶銑の脱りん方法。 As a result, the following invention was devised.
(1)
2 to 20% by mass of Al 2 O 3 with the balance being calcium ferrite and impurities,
A molten iron dephosphorizing agent having an (Al 2 O 3 mass%) / (CaO mass%) ratio of 0.04 to 0.5.
(2)
Further, the molten iron dephosphorizing agent according to (1), which contains 1 to 10% by mass of SiO 2 and has a ratio of (SiO 2 % by mass) / (CaO mass%) of 0.04 to 0.3. 3)
Further (Na 2 O wt%) / (Al 2 O 3 wt%) ratio contains Na 2 O of from 0.1 to 2.0 as described in any one of (1) or (2) Molten iron dephosphorizer.
(4)
A refining agent comprising the dephosphorizing agent according to any one of (1) to (3).
(5)
(4) The refining agent described in (4) is added to the converter to perform dephosphorization of the hot metal, and the charging (CaO) / (SiO 2 ) ratio is 1.3 to 2.0. Dephosphorization method for molten iron.
(6)
The hot metal dephosphorization method according to (5), wherein the CaO mass contained in the calcium ferrite is 20% or more of the CaO mass contained in the scouring agent.
(7)
The hot metal dephosphorization method according to (5), wherein the refining agent is charged into the converter before the hot metal is charged.
　なお、本発明においてカルシウムフェライトとは、ＣａＯとＦｅ２Ｏ３を主成分とする化合物であって、ＣａＯとＦｅ２Ｏ３との割合は質量比で６：４～３：７であり、ＣａＯ質量％とＦｅ２Ｏ３質量％の合計は７０質量％以上のものを指す。また、カルシウムフェライトは、例えば、生石灰、鉄鉱石を原料とし、これらの混合物を、溶解炉により完全溶融し、冷却後に、１～５０mm程度の塊状に粉滓して製造される。また、低りん鋼とは鋳片段階での［Ｐ］が０．０２％以下の鋼を、効率的とは溶解したカルシウムフェライトが、十分に脱りんに寄与することを指す。また、特に断らない限り、短時間の吹錬とは、吹錬時間が約２～６分程度の吹錬のことを指す。 Note that the calcium ferrite in the present invention, a compound mainly containing CaO and Fe 2 O 3, 6 in the ratio weight ratio of CaO and Fe 2 O 3: 4 ~ 3 : a 7, CaO The sum of mass% and Fe 2 O 3 mass% refers to 70 mass% or more. Calcium ferrite is produced, for example, using quick lime and iron ore as raw materials, and a mixture of these is completely melted in a melting furnace, and after cooling, it is ground into a lump of about 1 to 50 mm. Further, low phosphorus steel refers to steel whose [P] at the slab stage is 0.02% or less, and efficient means that dissolved calcium ferrite sufficiently contributes to dephosphorization. Unless otherwise specified, short-time blowing refers to blowing with a blowing time of about 2 to 6 minutes.
　以下に上記発明に至った経緯と考え方について記す。
　本発明者らは上底吹き転炉の脱りんプロセスにおけるカルシウムフェライトの溶融性改善のため、ＣａＯおよびＦｅ２Ｏ３に種々の化合物を添加し、これを溶解炉で完全溶融した種々のカルシウムフェライトを作成した。また、ＣａＯとＦｅ２Ｏ３及びもしくは、Ａｌ２Ｏ３を混合し、常温でペレット状に成形したもの（以後、ペレットと称す）を作成した。次に赤外線ゴールドイメージ炉を搭載した高温顕微鏡を用いて、これらカルシウムフェライトおよびペレットを２００℃/ｍｉｎの昇温速度で加熱し、溶融開始温度と溶融終了温度を測定した。 The background and way of thinking that led to the above invention will be described below.
The present inventors added various compounds to CaO and Fe 2 O 3 in order to improve the meltability of calcium ferrite in the dephosphorization process of the top-bottom blown converter, and various calcium ferrites that were completely melted in a melting furnace. It was created. Also, CaO and Fe 2 O 3 and / or Al 2 O 3 were mixed and formed into a pellet at normal temperature (hereinafter referred to as pellet). Next, using a high-temperature microscope equipped with an infrared gold image furnace, the calcium ferrite and pellets were heated at a rate of temperature increase of 200 ° C./min, and the melting start temperature and the melting end temperature were measured.
　その結果、通常のＣａＯおよびＦｅ２Ｏ３からなるカルシウムフェライト（以後、ＣＦと記すことがある）に対して、ＣａＯ、Ｆｅ２Ｏ３およびＡｌ２Ｏ３からなるカルシウムフェライト（以後、ＣＦＡと記すことがある）は、溶融開始温度と溶融終了温度が著しく低いことを見出した。これは、Ａｌ２Ｏ３がカルシウムフェライトの固相線温度および液相線温度を下げる効果によるものと考えられた。また、上記ＣＦＡと同様の組成からなるペレットを用いた実験において、同様の組成であっても、ペレットの溶融開始温度、溶融終了温度はＣＦＡより高いことを確認した。 As a result, calcium ferrite composed of CaO, Fe 2 O 3 and Al 2 O 3 (hereinafter referred to as CFA) is compared with calcium ferrite composed of ordinary CaO and Fe 2 O 3 (hereinafter sometimes referred to as CF). Has found that the melting start temperature and the melting end temperature are extremely low. This was thought to be due to the effect that Al 2 O 3 lowers the solidus temperature and liquidus temperature of calcium ferrite. Moreover, in the experiment using the pellet which consists of the composition similar to the said CFA, even if it was the same composition, it was confirmed that the melting start temperature and melting end temperature of a pellet are higher than CFA.
　上記実験ではＣＦＡの液相線温度は溶融終了温度から１３５０℃以下と推定され、ＣＦの液相線温度（約１４００℃）に対して低いことから、上底吹き転炉における脱りん吹錬にＣＦＡを使用すること、ＣＦを使用した場合に対して溶解速度は増大し、脱りんが促進すると考えられた。また、ＣＦＡを製造する過程で、事前に原料を溶解しておくことも溶解速度を増大する上で重要であると考えられた。一方で、Ａｌ２Ｏ３は転炉スラグの粘度を増大させるため、転炉スラグのＡｌ２Ｏ３濃度が高くなりすぎると、転炉内で急激なスラグフォーミングが起こり、転炉炉口からスラグが飛散する（以後、スロッピングと記す）頻度が高くなり、吹錬を中断せざるをえない。本発明者らは、このような状況を防止する適正なＡｌ２Ｏ３濃度を調査し、カルシウムフェライト中のＡｌ２Ｏ３を２０質量％以下とすることで、スロッピングの頻度を抑制し、吹錬を中断することなく操業できることを見出した。 In the above experiment, the liquidus temperature of CFA is estimated to be 1350 ° C or less from the melting end temperature and is lower than the liquidus temperature of CF (about 1400 ° C). The use of CFA and the use of CF were considered to increase the dissolution rate and promote dephosphorization. In addition, it was considered that it is important to dissolve the raw material in advance in the process of producing CFA in order to increase the dissolution rate. On the other hand, since Al 2 O 3 increases the viscosity of the converter slag, if the Al 2 O 3 concentration in the converter slag becomes too high, rapid slag forming occurs in the converter, and slag is generated from the converter furnace port. The frequency of splattering (hereinafter referred to as slopping) increases, and blowing must be interrupted. The present inventors thus situation investigated proper concentration of Al 2 O 3 to prevent such, by the Al 2 O 3 calcium ferrite and 20% by mass or less to suppress the frequency of slopping, I found that I could operate without interrupting blowing.
　また、Ａｌ２Ｏ３濃度が低すぎると、カルシウムフェライトの溶解速度が小さく、短時間の吹錬で低りん鋼を溶製することが困難であったため、Ａｌ２Ｏ３濃度を２質量％以上とした。さらに本発明者らは、Ａｌ２Ｏ３濃度を４～１２質量％とすることでより高い効果を発現できることを確認した。 In addition, when the Al 2 O 3 concentration is too low, the dissolution rate of calcium ferrite is small, and it is difficult to produce low phosphorus steel by short-time blowing, so the Al 2 O 3 concentration is 2% by mass or more. It was. Furthermore, the present inventors have confirmed that a higher effect can be exhibited by setting the Al 2 O 3 concentration to 4 to 12% by mass.
　また、カルシウムフェライト中のＡｌ２Ｏ３濃度が高くなることで、カルシウムフェライトの溶解速度が増大するが、脱りんに必要なカルシウムフェライト中のＣａＯ濃度が、相対的に低くなるため、脱りんに対して、カルシウムフェライトのＡｌ２Ｏ３濃度とＣａＯ濃度には適正な組成が存在すると考えられる。この適正組成について、本発明者らは鋭意検討し、（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比を０．０４～０．５とすることで、低りん鋼を溶製できることを確認した。（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．０４未満の場合、カルシウムフェライトの溶解速度が小さく、脱りんが不十分である。また（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．５より大きい場合、ＣａＯ濃度が低すぎて脱りんが悪化する。なお、本発明者らは（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比を０．１～０．３に制御することで、より高い効果を発現し、さらに脱りんが促進することを確認した。 Moreover, although the dissolution rate of calcium ferrite increases by increasing the Al 2 O 3 concentration in calcium ferrite, the CaO concentration in calcium ferrite necessary for dephosphorization becomes relatively low. On the other hand, it is considered that there is an appropriate composition for the Al 2 O 3 concentration and the CaO concentration of calcium ferrite. With regard to this appropriate composition, the present inventors have intensively studied and found that low phosphorus steel can be produced by setting the (Al 2 O 3 mass%) / (CaO mass%) ratio to 0.04 to 0.5. confirmed. When the (Al 2 O 3 mass%) / (CaO mass%) ratio is less than 0.04, the dissolution rate of calcium ferrite is low and dephosphorization is insufficient. In the case (Al 2 O 3 wt%) / (CaO mass%) ratio of greater than 0.5, CaO concentration is too by dephosphorization is degraded low. In addition, the present inventors can achieve a higher effect and further promote dephosphorization by controlling the (Al 2 O 3 mass%) / (CaO mass%) ratio to 0.1 to 0.3. It was confirmed.
　さらに本発明者らは、前述の赤外線ゴールドイメージ炉を搭載した高温顕微鏡を用いた実験により、ＣａＯ、Ｆｅ２Ｏ３、Ａｌ２Ｏ３およびＮａ２Ｏを含むカルシウムフェライト（以後、ＣＦＡＮと記すことがある）は、ＣＦＡに対して溶融開始温度および溶融終了温度が、更に低いことを明らかにした。これは、Ｎａ２ＯがＣＦＡの液相線温度および固相線温度を下げる効果を持つためと考えられ、ＣＦＡＮの液相線温度は溶融終了温度から１３３０℃以下と推定された。 Furthermore, the present inventors conducted a test using a high-temperature microscope equipped with the above-described infrared gold image furnace, and obtained calcium ferrite containing CaO, Fe 2 O 3 , Al 2 O 3 and Na 2 O (hereinafter referred to as CFAN). Revealed that the melting start temperature and the melting end temperature are lower than those of CFA. This is presumably because Na 2 O has the effect of lowering the liquidus temperature and solidus temperature of CFA, and the liquidus temperature of CFAN was estimated to be 1330 ° C. or less from the melting end temperature.
　また、上底吹き転炉の脱りんプロセスにおいて、ＣＦＡより、ＣＦＡＮの方が高い脱りん効率を示し、より［Ｐ］が低い鋼を溶製できることを確認した。これは、Ｎａ２Ｏがスラグのフォスフェイトキャパシティーを増大する効果をもつこと、Ｎａ２Ｏが転炉スラグの粘度を下げ、スラグ側のりんの物質移動を促進する効果を有することが原因と推定される。 Moreover, in the dephosphorization process of the top-bottom blow converter, it was confirmed that CFAN showed higher dephosphorization efficiency than CFA, and it was possible to produce steel with lower [P]. This can have the effect of Na 2 O increases the phosphate capacity of the slag, Na 2 O is lower the viscosity of the converter slag, and because it has the effect of promoting mass transfer of phosphorus slag side Presumed.
　ＣＦＡにおいて、Ａｌ２Ｏ３濃度を、Ａｌ２Ｏ３が２～２０質量％、（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比を０．０４～０．５とすることで、カルシウムフェライトの溶解速度が増大し、この効果により脱りんを促進することを述べた。一方で、Ａｌ２Ｏ３の添加はスラグの粘度を増大させて、スラグ側のりんの物質移動を遅滞する効果を有している。Ｎａ２Ｏは、このＡｌ２Ｏ３添加によって増大した転炉スラグの粘度を低減する効果を持つことから、カルシウムフェライトのＡｌ２Ｏ３濃度とＮａ２Ｏ濃度は脱りんを促進するうえで適正な質量比が存在すると考えられる。 In CFA, Al a 2 O 3 concentration, Al 2 O 3 is 2-20 wt%, With (Al 2 O 3 wt%) / (CaO mass%) Ratio 0.04 to 0.5 and the calcium It was stated that the dissolution rate of ferrite increases and this effect promotes dephosphorization. On the other hand, the addition of Al 2 O 3 has the effect of increasing the viscosity of the slag and delaying the phosphorus mass transfer on the slag side. Na 2 O is from having the effect of reducing the viscosity of the converter slag was increased by the Al 2 O 3 added, Al 2 O 3 concentration and concentration of Na 2 O Calcium ferrite money in promoting the dephosphorization It is considered that there is a large mass ratio.
　この質量比について、本発明者らは鋭意検討し、（Ｎａ２Ｏ質量％）／（Ａｌ２Ｏ３質量％）比を０．１より大きくすることで、ＣＦＡに対して、より［Ｐ］が低い鋼を溶製できることを確認した。また、（Ｎａ２Ｏ質量％）／（Ａｌ２Ｏ３質量％）比が２．０より大きい場合、脱りんが悪化した。これは、転炉スラグ中のＮａ２Ｏに対するＡｌ２Ｏ３の質量比が下がることで、Ｎａ２Ｏの活量が大きくなり、Ｎａ２Ｏのガス化が進行したことで、脱りんに必要なＮａ２Ｏを脱りんスラグに供給できなかったためと推定された。 With regard to this mass ratio, the present inventors diligently studied, and by making the (Na 2 O mass%) / (Al 2 O 3 mass%) ratio greater than 0.1, the [P] It was confirmed that low steel can be melted. Further, when the (Na 2 O mass%) / (Al 2 O 3 mass%) ratio was larger than 2.0, the dephosphorization was deteriorated. This is because the mass ratio of Al 2 O 3 with respect to Na 2 O of the converter slag is lowered, Na activity of 2 O increases, that Na 2 O gasification has proceeded, dephosphorization as required It was estimated that Na 2 O could not be supplied to the dephosphorization slag.
　なお、（Ｎａ２Ｏ質量％）／（Ａｌ２Ｏ３質量％）比を０．２～１．８とすることで、脱りんを促進しつつ、スラグへのＮａ２Ｏの歩留りを高く維持できることを確認した。また、ＣＦＡに対して、ＣＦＡＮは、転炉内でのスラグフォーミングが抑制され、転炉炉口やランスへの地金付着の抑制など操業安定化に寄与することがわかった。これは、Ｎａ２Ｏによる転炉スラグの粘度低減により、転炉スラグのフォーミングやスロッピングが抑制されたためと考えられた。 By setting the ratio of (Na 2 O mass%) / (Al 2 O 3 mass%) to 0.2 to 1.8, it is possible to maintain a high yield of Na 2 O in the slag while promoting dephosphorization. I confirmed that I can do it. In contrast to CFA, it was found that CFAN contributes to operational stability, such as suppression of slag forming in the converter and suppression of metal adhesion to the converter furnace port and lance. This is considered to be because the forming and slopping of the converter slag were suppressed by the reduction of the viscosity of the converter slag by Na 2 O.
　また、本発明者らは、前述の赤外線ゴールドイメージ炉を搭載した高温顕微鏡を用いた実験により、ＣａＯ、Ｆｅ２Ｏ３、Ａｌ２Ｏ３およびＳｉＯ２からなるカルシウムフェライト（以後、ＣＦＡＳと称すこともある）においても、ＣＦに対して溶融開始温度および溶融終了温度が低いことを明らかにした。これは、ＳｉＯ２がＣＦの液相線温度および固相線温度を下げる効果を持つためと考えられた。一方で、ＳｉＯ２は転炉スラグの塩基度を低下するため、転炉スラグのＳｉＯ２濃度が高くなりすぎると、脱りん反応の進行が抑制され、吹錬終了時に目標とする[P]レベルを満足することが出来ない。本発明者らは、このような状況を防止する適正なＳｉＯ２濃度を調査し、カルシウムフェライト中のＳｉＯ２を１０質量％以下とすることで、目標[P]レベルを満足することを確認した。 In addition, the present inventors conducted an experiment using a high-temperature microscope equipped with the above-described infrared gold image furnace, and obtained calcium ferrite composed of CaO, Fe 2 O 3 , Al 2 O 3 and SiO 2 (hereinafter referred to as CFAS). The melting start temperature and the melting end temperature are lower than those of CF. This was considered because SiO 2 had the effect of lowering the liquidus temperature and solidus temperature of CF. On the other hand, since SiO 2 reduces the basicity of converter slag, if the SiO 2 concentration of converter slag becomes too high, the progress of the dephosphorization reaction is suppressed, and the target [P] level at the end of blowing Can not be satisfied. The present inventors investigated an appropriate SiO 2 concentration for preventing such a situation, and confirmed that the target [P] level was satisfied by making SiO 2 in calcium ferrite 10 mass% or less. .
　また、ＳｉＯ２濃度が低すぎると、溶融温度を低下する効果が確認出来なかったため、ＳｉＯ２濃度を１質量％以上とした。さらに本発明者らは、ＳｉＯ２濃度を２～５質量％とすることでより高い効果を発現できることを確認した。 Also, when the SiO 2 concentration is too low, the effect to lower the melting temperature could not be confirmed, and the SiO 2 concentration of 1% by mass or more. Furthermore, the present inventors have confirmed that a higher effect can be exhibited by setting the SiO 2 concentration to 2 to 5% by mass.
　また、本発明者らはＣＦＡＳ中のＳｉＯ２とＣａＯの適正組成について、鋭意検討し、（ＳｉＯ２質量％）／（ＣａＯ質量％）比を０．０４～０．３とすることで、低りん鋼を溶製できることを確認した。（ＳｉＯ２質量％）／（ＣａＯ質量％）比が０．０４未満の場合、カルシウムフェライトの溶解速度が小さく、脱りんが不十分である。また（ＳｉＯ２質量％）／（ＣａＯ質量％）比が０．３より大きい場合、ＣａＯ濃度が低すぎて脱りんが悪化する。なお、本発明者らは（ＳｉＯ２質量％）／（ＣａＯ質量％）比を０．１～０．３に制御することで、より高い効果を発現し、さらに脱りんが促進することを確認した。 In addition, the present inventors diligently studied about the proper composition of SiO 2 and CaO in CFAS, and by setting the ratio of (SiO 2 mass%) / (CaO mass%) to 0.04 to 0.3, low It was confirmed that phosphorus steel could be melted. When the (SiO 2 mass%) / (CaO mass%) ratio is less than 0.04, the dissolution rate of calcium ferrite is low and dephosphorization is insufficient. If the (SiO 2 mass%) / (CaO mass%) ratio is greater than 0.3, the CaO concentration is too low and the dephosphorization is worsened. In addition, the present inventors have confirmed that by controlling the (SiO 2 mass%) / (CaO mass%) ratio to 0.1 to 0.3, a higher effect is exhibited and further dephosphorization is promoted. did.
　さらに本発明者らは、前述の赤外線ゴールドイメージ炉を搭載した高温顕微鏡を用いた実験により、ＣａＯ、Ｆｅ２Ｏ３、Ａｌ２Ｏ３、ＳｉＯ２およびＮａ２Ｏを含むカルシウムフェライト（以後、ＣＦＡＳＮと記すことがある）は、ＣＦＡＳに対して溶融開始温度および溶融終了温度が、更に低いことを明らかにした。これは、Ｎａ２ＯがＣＦＡＳの液相線温度および固相線温度を下げる効果を持つためと考えられた。 Furthermore, the present inventors conducted an experiment using a high-temperature microscope equipped with the above-described infrared gold image furnace, and obtained calcium ferrite containing CaO, Fe 2 O 3 , Al 2 O 3 , SiO 2 and Na 2 O (hereinafter referred to as CFASN). ) Revealed that the melting start temperature and the melting end temperature were even lower than CFAS. This was thought to be because Na 2 O had the effect of lowering the liquidus temperature and solidus temperature of CFAS.
　また、上底吹き転炉の脱りんプロセスにおいて、ＣＦＡＳより、ＣＦＡＳＮの方が高い脱りん効率を示し、より［Ｐ］が低い鋼を溶製できることを確認した。これは、Ｎａ２Ｏがスラグのフォスフェイトキャパシティーを増大する効果をもつこと、Ｎａ２Ｏが転炉スラグの粘度を下げ、スラグ側のりんの物質移動を促進する効果を有することが原因と推定される。 Further, in the dephosphorization process of the top-bottom blow converter, it was confirmed that CCASN showed higher dephosphorization efficiency than CFAS, and it was possible to produce steel with lower [P]. This can have the effect of Na 2 O increases the phosphate capacity of the slag, Na 2 O is lower the viscosity of the converter slag, and because it has the effect of promoting mass transfer of phosphorus slag side Presumed.
　また、本発明者らはＣＦＡＳＮ中のＳｉＯ２とＮａ２Ｏの適正組成について、鋭意検討し、（Ｎａ２Ｏ質量％）／（ＳｉＯ２質量％）比を０．１より大きくすることで、ＣＦＡＳに対して、より［Ｐ］が低い鋼を溶製できることを確認した。また、（Ｎａ２Ｏ質量％）／（ＳｉＯ２質量％）比が３．０より大きい場合、脱りんが悪化した。これは、転炉スラグ中のＮａ２Ｏに対するＳｉＯ２の質量比が下がることで、Ｎａ２Ｏの活量が大きくなり、Ｎａ２Ｏのガス化が進行したことで、脱りんに必要なＮａ２Ｏを脱りんスラグに供給できなかったためと推定された。また、ＣＦＡＳＮ中のＳｉＯ２、Ａｌ２Ｏ３およびＮａ２Ｏの適正組成について検討し、（Ｎａ２Ｏ質量％）／（ＳｉＯ２質量％＋Ａｌ２Ｏ３質量％）比を、０．１～２.５が好ましいことを見出した。 In addition, the present inventors diligently studied about the proper composition of SiO 2 and Na 2 O in CFASN, and by making the (Na 2 O mass%) / (SiO 2 mass%) ratio larger than 0.1, It was confirmed that steel with a lower [P] can be melted relative to CFAS. In addition, when the (Na 2 O mass%) / (SiO 2 mass%) ratio was larger than 3.0, dephosphorization deteriorated. This is because the mass ratio of SiO 2 to Na 2 O of the converter slag is lowered, the greater the activity of Na 2 O, Na 2 by O gasification has proceeded, dephosphorizing the required Na It was estimated that 2 O could not be supplied to the dephosphorization slag. Also, the proper composition of SiO 2 , Al 2 O 3 and Na 2 O in CFASN was examined, and the ratio of (Na 2 O mass%) / (SiO 2 mass% + Al 2 O 3 mass%) was 0.1 to 2.5 was found to be preferred.
　ＣＦＡを製造する際のＡｌ２Ｏ３源としては、アルミ灰、アルミナ系耐火物およびＡｌ２Ｏ３を含む製鋼スラグ等、ＣＦＡＳを製造する際のＳｉＯ２源としては、橄欖岩、軽石、ＳｉＯ2を含む製鋼スラグ等がある。また、ＣＦＡＮおよびＣＦＡＳＮのＮａ２Ｏ源としては、Ｎａ２ＣＯ３，ソーダ石灰ガラス、メタケイ酸ソーダ等がある。 Examples of the Al 2 O 3 source for producing CFA include aluminum ash, alumina-based refractories, and steelmaking slag containing Al 2 O 3. Examples of the SiO 2 source for producing CFAS include peridotite, pumice, SiO 2 There are steelmaking slag including 2 . Examples of Na 2 O sources for CFAN and CFASN include Na 2 CO 3 , soda lime glass, and sodium metasilicate.
　本発明によれば、上底吹き転炉における脱りん処理において、Ａｌ２Ｏ３を適正濃度で含有したカルシウムフェライトを用いることで、短時間の吹錬であっても十分に精錬剤が溶解し、効率的に低りん鋼を溶製することができる。さらに、Ａｌ２Ｏ３に加えてＮａ２ＯおよびもしくはＳｉＯ２を適正量加えることにより、脱りんをさらに促進することができる。 According to the present invention, in the dephosphorization treatment in the top-bottom blowing converter, by using calcium ferrite containing Al 2 O 3 at an appropriate concentration, the refining agent is sufficiently dissolved even in a short time of blowing. It is possible to melt low phosphorus steel efficiently. Furthermore, dephosphorization can be further promoted by adding an appropriate amount of Na 2 O and / or SiO 2 in addition to Al 2 O 3 .
本発明に係る上底吹き転炉を用いた脱りんプロセスの概略を示す説明図である。It is explanatory drawing which shows the outline of the dephosphorization process using the top bottom blowing converter which concerns on this invention.
　つぎに、本発明に係る脱りん剤を用いて脱りん処理を行う際の形態を説明する。
　製鋼の精錬工程で用いられる精錬炉としては、通常、転炉が用いられ、転炉法による製鋼工程においては、主原料として溶銑とスクラップを装入して溶鋼が生産される。図１に、上底吹き転炉を用いた精錬工程の概略を示す。 Below, the form at the time of performing a dephosphorization process using the dephosphorizing agent which concerns on this invention is demonstrated.
As the refining furnace used in the steelmaking refining process, a converter is usually used. In the steelmaking process using the converter method, molten steel and scrap are charged as main raw materials to produce molten steel. In FIG. 1, the outline of the refining process using an upper bottom blowing converter is shown.
　最初に、図１（ａ）に示すように、転炉１内にスクラップ２を装入する。そして、スクラップ２の装入と同時に、本発明に係る脱りん剤であるＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮの少なくともいずれかを含む精錬剤３を炉内に投入する。ＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮの粒径は１～５０ｍｍ、好ましくは５～３５ｍｍ程度の粒径のものを使用することができる。 First, as shown in FIG. 1A, the scrap 2 is charged into the converter 1. Simultaneously with the charging of the scrap 2, a refining agent 3 containing at least one of CFA, CFAN, CFAS, and CFASN, which are dephosphorizing agents according to the present invention, is charged into the furnace. CFA, CFAN, CFAS, and CCASN may have a particle size of about 1 to 50 mm, preferably about 5 to 35 mm.
　また、製鋼スラグ発生量削減および製造コスト削減の点から、ＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮを使用する際の転炉スラグの装入塩基度は１．３～２．０が好ましい。装入塩基度とは、「転炉内へ供給する副原料中に含まれるＣａＯ質量の合計」を分子とし、「転炉内へ供給する副原料中に含まれるＳｉＯ２質量の合計」と「溶銑およびスクラップ中に含まれているＳｉが全部ＳｉＯ２に酸化されたとした場合のＳｉＯ２質量」との合計を分母として計算される比の数値である。また、本発明に係る脱りん剤の効果を十分に得るためには、カルシウムフェライトから供給するＣａＯ量が、転炉内へ供給する精錬剤３に含まれる全ＣａＯ質量の２０％以上であることが好ましい。 Further, from the viewpoint of reducing the amount of steelmaking slag generated and reducing the manufacturing cost, the charging basicity of the converter slag when using CFA, CFAN, CFAS, CFASN is preferably 1.3 to 2.0. The charge basicity refers to “the total amount of CaO contained in the auxiliary raw material supplied into the converter” as a molecule, and “the total amount of SiO 2 contained in the auxiliary raw material supplied into the converter” and “ Si contained in the molten iron and scrap is a number of the ratio is calculated the sum of the SiO 2 mass "in the case of the oxidized to the total SiO 2 as a denominator. In order to sufficiently obtain the effect of the dephosphorizing agent according to the present invention, the amount of CaO supplied from calcium ferrite is 20% or more of the total CaO mass contained in the refining agent 3 supplied into the converter. Is preferred.
　スクラップ２および精錬剤３を装入した後、炉内に溶銑４を装入（図１（ｂ））し、その後、ランス５から酸素を溶銑４に吹き込む吹錬を行う（図１（ｃ））。 After the scrap 2 and the refining agent 3 are charged, the hot metal 4 is charged into the furnace (FIG. 1 (b)), and then blown by blowing oxygen from the lance 5 into the hot metal 4 (FIG. 1 (c)). ).
　吹錬によって、溶銑３中のりんが酸素およびスラグ中のＣａＯと反応して、スラグ側に移行する。通常、ＣａＯ源として生石灰は高融点であり、精錬時の溶銑温度での溶解速度は小さいが、本発明に係る脱りん剤であるＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮは溶銑温度で溶融するため溶解速度が大きく、スラグ中のＣａＯ濃度を早期に上昇することで、溶銑の脱りんを促進することができる。 Blowing causes phosphorus in hot metal 3 to react with oxygen and CaO in slag and shift to the slag side. Normally, quick lime as a CaO source has a high melting point, and the dissolution rate at the hot metal temperature during refining is small. However, the dephosphorization agents CFA, CFAN, CFAS, and CFASN according to the present invention melt at the hot metal temperature, so the dissolution rate. Therefore, dephosphorization of hot metal can be promoted by increasing the CaO concentration in the slag early.
　本発明において、ＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮのいずれかを含む精錬剤３の投入は、転炉内に溶銑４を装入した後でも効果を発現するが、溶銑４の装入前に精錬剤３を投入しておくことが好ましい。これは、溶銑４の装入時の撹拌力を利用して、ＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮの溶解を促進するためである。あるいは、精錬剤のうちＣＦＡ、ＣＦＡＮ、ＣＦＡＳ、ＣＦＡＳＮのみを溶銑４の装入前に投入し、精錬剤のその他の物質を吹錬時に投入してもよい。 In the present invention, the charging of the refining agent 3 containing any one of CFA, CFAN, CFAS, and CCASN is effective even after the hot metal 4 is charged in the converter, but the refining agent is charged before the hot metal 4 is charged. 3 is preferably charged. This is to promote dissolution of CFA, CFAN, CFAS, and CFASN by utilizing the stirring force when the molten iron 4 is charged. Alternatively, only CFA, CFAN, CFAS, and CCASN among the refining agents may be charged before the molten iron 4 is charged, and other materials of the refining agent may be charged at the time of blowing.
　ＣａＯおよびＦｅ２Ｏ３からなるカルシウムフェライトは上述の通りＣａＯの溶融性を改善した化合物であり、生石灰等に対して溶融しやすく、脱りん効果を発揮することは周知であるが、本発明に係る脱りん剤であるＡｌ２Ｏ３、もしくは、さらに、ＳｉＯ２もしくは、Ｎａ２Ｏを含有するカルシウムフェライトを用いることで、さらに融点が下がり、脱りん効果を高めることができる。 Calcium ferrite composed of CaO and Fe 2 O 3 is a compound that has improved the melting property of CaO as described above, and it is well known that it melts easily against quicklime and exhibits a dephosphorization effect. By using Al 2 O 3 which is such a dephosphorizing agent or calcium ferrite containing SiO 2 or Na 2 O, the melting point is further lowered, and the dephosphorizing effect can be enhanced.
　脱りんを行う精錬の形態としては、脱りんを行った後に別の炉で脱炭を行う場合と、ＭＵＲＣ（Ｍｕｌｔｉ　Ｒｅｆｉｎｉｎｇ　Ｃｏｎｖｅｒｔｅｒ）法と呼ばれる、脱りんを行った後、転炉を傾動してりん濃度が高いスラグを排出し、その後同一炉で継続して脱炭を行う場合等がある。本発明は、いずれの場合にも適用できるが、殊にＭＵＲＣ法では、脱りん時の吹錬時間が通常４分以内と短時間であり、このような場合でも、本発明に係る脱りん剤による脱りん方法によれば効率よく脱りん処理が行える。 As a form of refining that performs dephosphorization, the decarburization is performed in another furnace after dephosphorization, and the converter is tilted after dephosphorization, which is called MURC (Multi-Refining Converter) method. There are cases where slag with high phosphorus concentration is discharged and then decarburization is continued in the same furnace. Although the present invention can be applied to any case, in particular, in the MURC method, the blowing time during dephosphorization is usually as short as 4 minutes, and even in such a case, the dephosphorizing agent according to the present invention is used. According to the dephosphorization method, the dephosphorization process can be performed efficiently.
　以上、本発明の好適な実施形態について説明したが、本発明はかかる例に限定されない。当業者であれば、特許請求の範囲に記載された技術的思想の範疇内において、各種の変更例または修正例に想到しうることは明らかであり、それらについても当然に本発明の技術的範囲に属するものと了解される。 The preferred embodiments of the present invention have been described above, but the present invention is not limited to such examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.
　表１に示す種々のカルシウムフェライトを用いて、転炉での脱りん処理を行った。脱りん処理の条件は、脱りん前［Ｐ］が０．１％、吹錬時間が３～４分、装入塩基度が１．８、カルシウムフェライト使用量が１０ｋｇ／ｔの条件である。表中の成品［Ｐ］は、鋳片段階での［Ｐ］である。また、脱りん吹錬中に転炉炉口からのスロッピングの状況を調査し、スロッピングが原因で吹錬を途中で中断した場合は「有」とし、中断しなかった場合を「無」とした。また投入タイミングとは、カルシウムフェライトを転炉内に投入するタイミングであり、「溶銑装入前」もしくは「溶銑装入後」とした。 Using various calcium ferrites shown in Table 1, dephosphorization treatment in a converter was performed. The conditions for the dephosphorization treatment are as follows: [P] before dephosphorization is 0.1%, blowing time is 3 to 4 minutes, charging basicity is 1.8, and the amount of calcium ferrite used is 10 kg / t. The product [P] in the table is [P] at the slab stage. Also, during the dephosphorization blowing process, investigate the state of slopping from the converter furnace mouth. If the blowing process is interrupted due to slopping, it is set to “Yes”. It was. The charging timing is the timing at which calcium ferrite is charged into the converter, and is “before hot metal charging” or “after hot metal charging”.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明例であるＮｏ．１～Ｎｏ．９は成品［Ｐ］＜０．０２％を達成し、特にＮｏ．３、Ｎｏ．４、Ｎｏ．８およびＮｏ．９は成品［Ｐ］＜０．０１５％であり、より優れた脱りん能を示すことがわかった。一方で、比較例であるＮｏ．１０～１６はいずれも成品［Ｐ］＞０．０２％であり、脱りんが不十分であった。 No. which is an example of the present invention. 1-No. 9 achieved the product [P] <0.02%. 3, no. 4, no. 8 and no. No. 9 was a product [P] <0.015%, and it was found that it showed a better dephosphorization ability. On the other hand, No. which is a comparative example. In all of 10 to 16, the product [P]> 0.02%, and dephosphorization was insufficient.
　本発明剤であるＮｏ．１およびＮｏ．２は、Ａｌ２Ｏ３が３～２０質量％、（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．０４～０．５であり、Ａｌ２Ｏ３によりカルシウムフェライトの溶融が促進し、脱りんスラグへのＣａＯを供給速度が大きいため、脱りんが促進したと考えられる。一方でＮｏ．１０はＡｌ２Ｏ３が２質量％未満であり、カルシウムフェライトの溶解が不十分であったため、脱りんが不十分であったと考えられる。また、Ｎｏ．１１はＡｌ２Ｏ３濃度が２０質量％より大きいため、激しいスロッピングがおこり、吹錬を途中で中断したこと、（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．５より大きく、Ａｌ２Ｏ３濃度の上昇により、脱りんスラグへのＣａＯの供給量が少なかったことで脱りんが不十分であったと考えられる。 No. which is the agent of the present invention. 1 and no. 2, Al 2 O 3 3-20 wt%, (Al 2 O 3 wt%) / (CaO mass%) ratio of 0.04 to 0.5, and the melting of the calcium ferrite by Al 2 O 3 It is considered that the dephosphorization was promoted because the rate of supplying CaO to the dephosphorization slag was high. On the other hand, no. No. 10 has an Al 2 O 3 content of less than 2% by mass, and dissolution of calcium ferrite was insufficient. No. No. 11 has an Al 2 O 3 concentration of greater than 20% by mass, so that severe slopping occurred and the blowing was interrupted halfway, and the (Al 2 O 3 % by mass) / (CaO mass%) ratio was from 0.5. It is considered that dephosphorization was insufficient because the amount of CaO supplied to the dephosphorization slag was small due to the large increase in Al 2 O 3 concentration.
　また、本発明に係る脱りん剤であるＮｏ．３およびＮｏ．４は、Ａｌ２Ｏ３が２～２０質量％、（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．０４～０．５、さらに（Ｎａ２Ｏ）／（Ａｌ２Ｏ３）比が０．１～２．０であり、Ａｌ２Ｏ３およびＮａ２Ｏによりカルシウムフェライトの溶融が促進し、Ｎａ２Ｏがスラグのフォスフェイトキャパシティーを増大したこと、Ｎａ２Ｏが転炉スラグの粘度を下げスラグ側のりんの物質移動を促進したことで、本発明例であるＮｏ．１やＮｏ．２に対して、更に脱りんが促進したと考えられる。また、Ｎｏ．５は、カルシウムフェライトを転炉内に投入するタイミングが「溶銑装入後」であり、Ｎｏ．３およびＮｏ．４の「溶銑装入前」に対して、反応時間が短く、成品[Ｐ]は上昇したものの、成品［Ｐ］＜０．０２％を達成することが可能であった。 Moreover, No. which is a dephosphorizing agent according to the present invention. 3 and no. 4, Al 2 O 3 is 2 to 20 mass%, (Al 2 O 3 mass%) / (CaO mass%) ratio is 0.04 to 0.5, and (Na 2 O) / (Al 2 O 3 ) ratio is the 0.1 ~ 2.0, Al 2 O 3 and Na 2 O by promoting the melting of the calcium ferrite, the Na 2 O is increased the phosphate capacity of the slag, Na 2 O is rolling By reducing the viscosity of the furnace slag and promoting the mass transfer of phosphorous on the slag side, 1 or No. It is considered that dephosphorization was further promoted with respect to 2. No. No. 5 indicates that the timing at which calcium ferrite is charged into the converter is “after hot metal charging”. 3 and no. The reaction time was short and the product [P] increased with respect to 4 “before hot metal charging”, but it was possible to achieve the product [P] <0.02%.
　一方で、Ｎｏ．１２ではＡｌ２Ｏ３が２質量％より小さく、カルシウムフェライトの溶融が不十分であったこと、（Ｎａ２Ｏ）／（Ａｌ２Ｏ３）比が２．０より大きく、Ｎａ２Ｏの気化によりＮａ２Ｏが十分に脱りんスラグ中に残留しなかったことで、脱りんが不十分であったと考えられる。また、Ｎｏ．１３は、（Ｎａ２Ｏ）／（Ａｌ２Ｏ３）が０．１より小さく、Ｎａ２Ｏによりスラグのフォスフェイトキャパシティー、スラグ側のりんの物質移動速度を十分に大きくできなかったため、脱りんが不十分であったと考えられる。Ｎｏ．１４は（Ｎａ２Ｏ）／（Ａｌ２Ｏ３）比が２．０より大きく、Ｎａ２Ｏの気化によりＮａ２Ｏが十分に脱りんスラグ中に残留しなかったことで、脱りんが不十分であったと考えられる。 On the other hand, no. No. 12, Al 2 O 3 was smaller than 2% by mass, calcium ferrite was insufficiently melted, and the (Na 2 O) / (Al 2 O 3 ) ratio was larger than 2.0, and Na 2 O was vaporized. As a result, Na 2 O did not sufficiently remain in the dephosphorization slag, and it is considered that dephosphorization was insufficient. No. In No. 13, (Na 2 O) / (Al 2 O 3 ) was less than 0.1, and Na 2 O could not sufficiently increase the phosphate capacity of slag and the mass transfer rate of phosphorus on the slag side. It is thought that phosphorus was insufficient. No. No. 14 has a (Na 2 O) / (Al 2 O 3 ) ratio of greater than 2.0, and Na 2 O did not remain sufficiently in the dephosphorization slag due to vaporization of Na 2 O. It seems that it was enough.
　また、本発明に係る脱りん剤であるＮｏ．６およびＮｏ．７は、Ａｌ２Ｏ３が２～２０質量％、（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．０４～０．５、ＳｉＯ２が１～１０質量％、（ＳｉＯ２質量％）／（ＣａＯ質量％）比が０．０４～０．３であり、Ａｌ２Ｏ３およびＳｉＯ２によりカルシウムフェライトの溶融が促進し、脱りんスラグへのＣａＯを供給速度が大きいため、脱りんが促進したと考えられる。一方でＮｏ．１５はＡｌ２Ｏ３が２質量％未満、ＳｉＯ２が１質量％未満であり、カルシウムフェライトの溶解が不十分であったため、脱りんが不十分であったと考えられる。また、Ｎｏ．１６はＡｌ２Ｏ３濃度が２質量％未満、ＳｉＯ２が１０質量％以上であり、ＳｉＯ２によりスラグの塩基度が低下したことで、脱りんが不十分であったと考えられる。 Moreover, No. which is a dephosphorizing agent according to the present invention. 6 and no. 7 has a ratio of Al 2 O 3 of 2 to 20% by mass, (Al 2 O 3 % by mass) / (CaO mass%) of 0.04 to 0.5, SiO 2 of 1 to 10% by mass, (SiO 2 (Mass%) / (CaO mass%) ratio is 0.04 to 0.3, the melting of calcium ferrite is promoted by Al 2 O 3 and SiO 2, and the rate of supplying CaO to the dephosphorized slag is high. It seems that dephosphorization was promoted. On the other hand, no. In No. 15, Al 2 O 3 is less than 2% by mass and SiO 2 is less than 1% by mass, and the dissolution of calcium ferrite was insufficient, so it is considered that dephosphorization was insufficient. No. No. 16 has an Al 2 O 3 concentration of less than 2% by mass and SiO 2 of 10% by mass or more, and it is considered that dephosphorization was insufficient because the basicity of slag was lowered by SiO 2 .
　本発明は、製鋼工程において、鉄を含有するスクラップと溶銑を精錬炉に装入して吹錬し、溶鋼を溶製する際の脱りん処理方法に適用できる。 The present invention can be applied to a dephosphorization processing method in which steel-containing scrap and molten iron are charged into a smelting furnace and blown in a steelmaking process to melt the molten steel.
　１　　転炉
　２　　スクラップ
　３　　精錬剤
　４　　溶銑
　５　　ランス 1 Converter 2 Scrap 3 Refining agent 4 Hot metal 5 Lance

Claims (7)

  1. 　２～２０質量％のＡｌ２Ｏ３を含有し、残部がカルシウムフェライトと不純物であり、
    　（Ａｌ２Ｏ３質量％）／（ＣａＯ質量％）比が０．０４～０．５である、溶鉄の脱りん剤。     2 to 20% by mass of Al 2 O 3 with the balance being calcium ferrite and impurities,
    A molten iron dephosphorizing agent having an (Al 2 O 3 mass%) / (CaO mass%) ratio of 0.04 to 0.5.
  2. 　さらに、１～１０質量％のＳｉＯ２を含有し、（ＳｉＯ２質量％）／（ＣａＯ質量％）比が０．０４～０．３である、請求項１に記載の溶鉄の脱りん剤 The molten iron dephosphorizing agent according to claim 1, further comprising 1 to 10% by mass of SiO 2 and having a ratio of (SiO 2 % by mass) / (CaO mass%) of 0.04 to 0.3.
  3. 　さらに（Ｎａ２Ｏ質量％）／（Ａｌ２Ｏ３質量％）比が０．１～２．０となるＮａ２Ｏを含有する、請求項１または２のいずれか１項に記載の溶鉄の脱りん剤。 Further (Na 2 O wt%) / (Al 2 O 3 wt%) ratio contains Na 2 O of from 0.1 to 2.0 and the molten iron according to any one of claims 1 or 2 Dephosphorizer.
  4. 　請求項１～３のいずれか１項に記載の脱りん剤を含有する、精錬剤。 A refining agent containing the dephosphorizing agent according to any one of claims 1 to 3.
  5. 　請求項４に記載の精錬剤を転炉内に添加し、溶銑の脱りん処理を行う方法であって、装入（ＣａＯ）／（ＳｉＯ２）比が１．３～２．０である、溶鉄の脱りん方法。 A method of adding the refining agent according to claim 4 into a converter and performing a dephosphorization treatment of molten iron, wherein a charging (CaO) / (SiO 2 ) ratio is 1.3 to 2.0. Dephosphorization method for molten iron.
  6. 　前記カルシウムフェライトに含まれるＣａＯ質量が、前記精練剤に含まれるＣａＯ質量の２０％以上である、請求項５に記載の溶銑の脱りん方法。 The molten iron dephosphorization method according to claim 5, wherein a mass of CaO contained in the calcium ferrite is 20% or more of a mass of CaO contained in the scouring agent.
  7. 　前記精錬剤を溶銑の装入よりも前に前記転炉内に投入する、請求項５に記載の溶銑の脱りん方法。 The hot metal dephosphorization method according to claim 5, wherein the refining agent is charged into the converter before the hot metal is charged.
PCT/JP2016/089082 2016-01-05 2016-12-28 Molten iron dephosphorizing agent, refining agent, and dephosphorization method WO2017119392A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP2017560372A JP6481774B2 (en) 2016-01-05 2016-12-28 Molten iron dephosphorizing agent, refining agent and dephosphorizing method
KR1020187002603A KR102105353B1 (en) 2016-01-05 2016-12-28 Dephosphorization agent, refining agent and dephosphorization method of molten iron
CN201680045089.0A CN107849625A (en) 2016-01-05 2016-12-28 Dephosphorising agent, refining agent and the dephosphorization method of molten iron

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2016000488 2016-01-05
JP2016-000488 2016-01-05

Publications (1)

Publication Number Publication Date
WO2017119392A1 true WO2017119392A1 (en) 2017-07-13

Family

ID=59273677

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2016/089082 WO2017119392A1 (en) 2016-01-05 2016-12-28 Molten iron dephosphorizing agent, refining agent, and dephosphorization method

Country Status (5)

Country Link
JP (1) JP6481774B2 (en)
KR (1) KR102105353B1 (en)
CN (1) CN107849625A (en)
TW (1) TWI609839B (en)
WO (1) WO2017119392A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI683000B (en) * 2018-03-07 2020-01-21 日商日本製鐵股份有限公司 Method for dephosphorizing molten iron

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113943844B (en) 2021-10-19 2022-04-15 北京科技大学 Hot metal ladle dephosphorization-converter single decarburization steelmaking method
CN114657326B (en) * 2022-03-30 2024-04-02 北京科技大学 Dephosphorization agent and application thereof
CN114990276A (en) * 2022-07-04 2022-09-02 北京科技大学 Method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02232313A (en) * 1989-03-06 1990-09-14 Taiyo Giken Kogyo Kk Dephosphorizing agent for molten steel
CN101775465A (en) * 2009-12-31 2010-07-14 辽宁天和矿产有限公司 Dephosphorization agent for converter steelmaking and preparation method thereof
WO2013190591A1 (en) * 2012-06-18 2013-12-27 Ｊｆｅスチール株式会社 Refining method and molten steel production method
JP2014031562A (en) * 2012-08-06 2014-02-20 Nippon Steel & Sumitomo Metal Dephosphorization processing method of hot pig iron
JP2014040623A (en) * 2012-08-21 2014-03-06 Nippon Steel & Sumitomo Metal Dephosphorization method for molten iron

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001348610A (en) 2000-06-07 2001-12-18 Nippon Steel Corp Slag formation promoter
CN1600872A (en) * 2004-10-26 2005-03-30 上海彭浦冶金辅料有限公司 Dephosphorising agent for converter and preparation method
JP5525939B2 (en) 2010-07-02 2014-06-18 大阪鋼灰株式会社 Lime-based flux and its manufacturing method
CN102453788A (en) * 2010-10-21 2012-05-16 金素玉 Preparation method of converter steelmaking dephosphorizing agent
JP5360174B2 (en) 2011-09-15 2013-12-04 新日鐵住金株式会社 How to remove hot metal
JP5772645B2 (en) 2012-02-10 2015-09-02 新日鐵住金株式会社 Dephosphorization method for hot metal
CN102787212A (en) * 2012-06-28 2012-11-21 辽宁中汇环保科技有限公司 Steel-making dephosphorization agent and preparation method thereof
CN103981335B (en) * 2014-05-30 2015-11-18 重庆大学 A kind of vanadium-bearing hot metal vanadium extraction and dephosphorization agent
CN104593546B (en) * 2014-09-26 2016-07-06 洛阳金石再生资源开发有限公司 A kind of preparation method of pre-melted type calcium ferrite Dephosphorising agent

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02232313A (en) * 1989-03-06 1990-09-14 Taiyo Giken Kogyo Kk Dephosphorizing agent for molten steel
CN101775465A (en) * 2009-12-31 2010-07-14 辽宁天和矿产有限公司 Dephosphorization agent for converter steelmaking and preparation method thereof
WO2013190591A1 (en) * 2012-06-18 2013-12-27 Ｊｆｅスチール株式会社 Refining method and molten steel production method
JP2014031562A (en) * 2012-08-06 2014-02-20 Nippon Steel & Sumitomo Metal Dephosphorization processing method of hot pig iron
JP2014040623A (en) * 2012-08-21 2014-03-06 Nippon Steel & Sumitomo Metal Dephosphorization method for molten iron

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI683000B (en) * 2018-03-07 2020-01-21 日商日本製鐵股份有限公司 Method for dephosphorizing molten iron

Also Published As

Publication number Publication date
TW201726550A (en) 2017-08-01
CN107849625A (en) 2018-03-27
KR20180021167A (en) 2018-02-28
JP6481774B2 (en) 2019-03-13
TWI609839B (en) 2018-01-01
JPWO2017119392A1 (en) 2018-04-05
KR102105353B1 (en) 2020-04-29

Similar Documents

Publication Publication Date Title
JP6481774B2 (en) Molten iron dephosphorizing agent, refining agent and dephosphorizing method
CN104032060A (en) Method for desulfurizing molten iron
JP5553167B2 (en) How to remove hot metal
JP4977870B2 (en) Steel making method
CN104032096B (en) A kind of method of desulfurization slag properties-correcting agent and desulfurizing iron
JP5983492B2 (en) Hot metal pretreatment method
JP5360174B2 (en) How to remove hot metal
JP4499969B2 (en) Desulfurization method by ladle refining of molten steel
JP2006009146A (en) Method for refining molten iron
JP5182322B2 (en) Hot phosphorus dephosphorization method
JP2008063646A (en) Dephosphorizing method of molten iron
JPS587691B2 (en) Steel manufacturing method
JP6627601B2 (en) Hot metal dephosphorizer and method
JP6460265B2 (en) Converter blowing method
JP4422318B2 (en) Hot metal dephosphorization method with little refractory damage
JP2004190114A (en) Method for dephosphorizing molten pig iron
JP4854933B2 (en) Refining method with high reaction efficiency
JP2019151535A (en) Method of producing phosphate slag fertilizer
JP5447554B2 (en) Dephosphorization method for hot metal
JP5803837B2 (en) Method of desiliconization and dephosphorization of hot metal
JP2002275521A (en) Method for dephosphorizing molten high carbon steel
JP2011058046A (en) Method for dephosphorizing molten iron
JP3733819B2 (en) How to remove hot metal
JP2007119813A (en) Method for refining molten iron
JP3704912B2 (en) Hot metal desiliconization and desulfurization methods

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 16883891

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2017560372

Country of ref document: JP

Kind code of ref document: A

ENP Entry into the national phase

Ref document number: 20187002603

Country of ref document: KR

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 16883891

Country of ref document: EP

Kind code of ref document: A1