JP4196997B2 - Hot metal processing method - Google Patents
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- JP4196997B2 JP4196997B2 JP2006048721A JP2006048721A JP4196997B2 JP 4196997 B2 JP4196997 B2 JP 4196997B2 JP 2006048721 A JP2006048721 A JP 2006048721A JP 2006048721 A JP2006048721 A JP 2006048721A JP 4196997 B2 JP4196997 B2 JP 4196997B2
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本発明は、溶銑の脱燐処理をより効率的に実施する溶銑の処理方法に関し、さらに詳しくは、脱珪処理した溶銑を、その脱珪処理により生成したスラグを除去せずに、または一部除去した後に転炉型脱燐炉に装入し、ＣａＯを含有する脱燐剤を上吹きランスから酸素をキャリアガスとして溶銑に吹き付けることにより脱燐処理を行う溶銑の処理方法に関する。 The present invention relates to a hot metal treatment method for more efficiently performing dephosphorization of hot metal, and more specifically, without removing slag generated by the desiliconization treatment or a part of the hot metal subjected to desiliconization treatment. The present invention relates to a hot metal treatment method in which dephosphorization treatment is performed by charging a hot metal into a converter-type dephosphorization furnace after removing it and spraying a dephosphorization agent containing CaO from an upper blowing lance with oxygen as a carrier gas.
近年の鋼材品質に対する要求の高度化を受けて、低燐鋼の需要が大幅に増加している。これに対応するため、溶銑段階において脱燐を施す溶銑予備処理が一般的となっている。従来、この溶銑予備脱燐においては、塊状の脱燐剤の滓化（溶融）を促進するために螢石などのハロゲン化物が滓化促進剤として使用されてきた。しかしながら、耐火物保護、ならびに、近年、重要度が急速に増大している地球環境保護および廃棄物の有効利用といった観点から、螢石の使用は望ましくなく、その対応策として幾つかの方法が提案されている。 The demand for low-phosphorus steel has greatly increased in response to the recent demand for steel quality. In order to cope with this, a hot metal preliminary treatment in which dephosphorization is performed in the hot metal stage has become common. Conventionally, in this hot metal preliminary dephosphorization, a halide such as meteorite has been used as a hatching accelerator in order to accelerate the hatching (melting) of the bulk dephosphorization agent. However, the use of meteorites is not desirable from the viewpoints of refractory protection, and the protection of the global environment and the effective use of waste, which have recently increased in importance, and several methods have been proposed as countermeasures. Has been.
例えば、特許文献１には、転炉型反応容器に収容された溶銑に対して上吹きランスより酸化カルシウム粉を酸素とともに吹き付けるとともに、反応容器の炉底かまたは側壁から攪拌用ガスを吹き込む溶銑脱燐方法が開示されている。また、この脱燐方法による脱燐能の高位安定化および滓化促進を目的として、特許文献２には、上底吹き転炉形式の炉に収容された溶銑に、上吹きランスから、ＣａＯ粉にＡｌ2Ｏ3粉またはさらにＦｅ2Ｏ3粉を混合した混合粉を吹き付けるとともに、炉底から攪拌用ガスを吹き込む溶銑の脱燐方法が開示されている。 For example, Patent Document 1 discloses hot metal removal in which calcium oxide powder is sprayed together with oxygen from an upper blowing lance against hot metal contained in a converter type reaction vessel, and stirring gas is blown from the furnace bottom or side wall of the reaction vessel. A phosphorus method is disclosed. Further, for the purpose of high-level stabilization of dephosphorization ability by this dephosphorization method and promotion of hatching, Patent Document 2 discloses that hot metal contained in a top bottom blown converter type furnace, CaO powder from a top blow lance, A hot metal dephosphorization method is disclosed in which Al 2 O 3 powder or a mixed powder in which Fe 2 O 3 powder is further mixed is sprayed on and a stirring gas is blown from the bottom of the furnace.
特許文献１または特許文献２に開示された脱燐方法により高い脱燐能を得るためには、スラグの装入塩基度をより高めることが望ましいが、塩基度が２．０を超えると、スラグの流動性が低下し、炉内からの排滓性が悪化する。そのため、これらの方法を連続して実施した場合には、炉内に付着および残留するスラグも増加し、その残留分の影響により、後の処理においてスラグの滓化性が著しく悪化し、脱燐能が大幅に低下するという問題がある。この問題への対策としては、スラグの装入塩基度を２．０以下とした条件下で連続処理することが考えられるが、塩基度を低下させることに起因する脱燐能の低下は避けられず、したがって、安定した脱燐処理を行うためにはスラグ量を増加させざるをえない。 In order to obtain high dephosphorization ability by the dephosphorization method disclosed in Patent Document 1 or Patent Document 2, it is desirable to further increase the basicity of the slag, but if the basicity exceeds 2.0, the slag The fluidity of the steel is reduced and the exhaustability from the furnace is deteriorated. Therefore, when these methods are carried out continuously, the amount of slag adhering to and remaining in the furnace also increases, and the influence of the residue causes the slag hatchability to deteriorate significantly in the subsequent treatment, and dephosphorization. There is a problem that the performance is greatly reduced. As a countermeasure against this problem, it is conceivable to carry out continuous treatment under a condition in which the basicity of slag is 2.0 or less, but a decrease in dephosphorization ability due to a decrease in basicity can be avoided. Therefore, the amount of slag must be increased in order to perform a stable dephosphorization process.
スラグ量は溶銑中のＳｉ含有率の影響を受けて決定される。近年では、高炉から出銑される溶銑中のＳｉ含有率は、安価な原燃料の使用を指向した操業方法の影響もあって、一般的には０．１０〜１．００質量％程度の変動幅を有している。したがって、溶銑中Ｓｉ含有率が低く必要スラグ量が不足している場合には、ＳｉＯ2を含有する副原料を添加してスラグの必要量を確保することとなる。その際に使用される副原料としては、珪石や橄欖岩などがあるが、これらは、その成分組成から予測される融点が１７００〜１９００℃程度と非常に高く、溶銑脱燐の処理温度域では溶融しにくい。そのため、スラグ量を確保するためにこれらの副原料を添加しても、実際にはスラグを形成しない未溶解分が発生し、その結果、スラグ量不足による脱燐不良が起こる。 The amount of slag is determined by the influence of the Si content in the hot metal. In recent years, the Si content in the hot metal discharged from the blast furnace is generally affected by fluctuations in the range of about 0.10 to 1.00% by mass due to the influence of the operation method directed to the use of inexpensive raw fuel. It has a width. Therefore, when the Si content in the hot metal is low and the required slag amount is insufficient, an auxiliary material containing SiO 2 is added to ensure the required amount of slag. The auxiliary materials used at that time include silica and peridotite, but these have a very high melting point predicted from the component composition of about 1700 to 1900 ° C., and in the hot metal dephosphorization processing temperature range. Difficult to melt. Therefore, even if these auxiliary materials are added in order to secure the slag amount, an undissolved portion that does not actually form slag is generated, and as a result, dephosphorization failure due to insufficient slag amount occurs.
一方、溶銑中Ｓｉ含有率が高い場合には、上記のようなスラグ量不足の懸念は無くなるものの、下記の問題が発生する。すなわち、(1)脱燐処理の初期において生成するＳｉＯ2量が多くなること、および(2)Ｓｉの燃焼による発熱量の増加に起因して温度調整のための冷材（ミルスケールや鉄鉱石などの酸化鉄）の投入量が増加し、それらと溶銑中のＣとの反応によるＣＯガス発生量が増加すること、の二つの要因によって、スロッピングの発生頻度が増加するという問題が発生する。スロッピングが発生すると、スラグ中に含まれる粒鉄も炉外へと流出するため鉄歩留まりが低下し、またスロッピングの程度が大きい場合には、飛散した高温のスラグによる転炉周辺設備の損傷などが予想され、深刻な問題となる。 On the other hand, when the Si content in the hot metal is high, the following problems occur, although there is no concern about the shortage of slag as described above. That is, (1) the amount of SiO 2 produced at the initial stage of the dephosphorization treatment is increased, and (2) the temperature control cold material (mill scale or iron ore due to the increase in the amount of heat generated by the combustion of Si) The increase in the frequency of slopping occurs due to the two factors of increasing the amount of iron oxide) and the like, and increasing the amount of CO gas generated by the reaction of C with hot metal. . When slopping occurs, the granular iron contained in the slag also flows out of the furnace, resulting in a decrease in iron yield. If the degree of slopping is large, damage to the equipment around the converter due to scattered high-temperature slag. This is a serious problem.
上述したように、脱燐剤を上吹き酸素とともに溶銑に吹き付ける溶銑の脱燐方法は、処理する溶銑の条件の変動に柔軟に対応できているとはいえず、従来、その対応方法についての提案もなされていない。しかしながら、溶銑の諸条件を常に一定に維持することは、現状では困難であり、上記の脱燐方法をさまざまな成分組成および温度を有する溶銑に適用するための対策が必要である。 As described above, the hot metal dephosphorization method in which the dephosphorizing agent is sprayed on the hot metal together with the overblown oxygen cannot be said to flexibly cope with fluctuations in the conditions of the hot metal to be treated. It has not been done. However, it is currently difficult to keep the hot metal conditions constant, and it is necessary to take measures to apply the above dephosphorization method to hot metal having various component compositions and temperatures.
また、粉体を上吹きする転炉精錬法では、スピッティングが発生しやすいため、粉体供給速度（ｋｇ／ｍｉｎ／ｔ−溶鋼）を高めて精錬能率を向上させるための方策が必要である。例えば、特許文献３には、ＣａＯ含有脱燐剤の吹き付けを開始する前に、生石灰、転炉スラグ、造塊スラグ、ドロマイトなどを投入して酸素を上吹きし、カバースラグを形成することによってスピッティングの発生を抑止する溶銑の脱燐方法が開示されている。しかし、この方法では、本来の脱燐処理である粉体上吹き吹錬のための時間が制約を受けることになるため、脱燐処理の能率や脱燐反応の効率を向上させるという面でなお課題が残されている。 Further, in the converter refining method in which powder is blown up, spitting is likely to occur, and therefore a measure for improving the refining efficiency by increasing the powder supply rate (kg / min / t-molten steel) is necessary. . For example, in Patent Document 3, before starting the spraying of the CaO-containing dephosphorization agent, quick lime, converter slag, ingot slag, dolomite, etc. are added and oxygen is blown up to form cover slag. A hot metal dephosphorization method that suppresses the occurrence of spitting is disclosed. However, in this method, the time for blow-on top of the powder, which is the original dephosphorization process, is limited, so that the efficiency of the dephosphorization process and the efficiency of the dephosphorization reaction are still improved. Challenges remain.
本発明は、上記の問題に鑑みてなされたものであり、その課題は、脱燐剤を上吹き酸素とともに溶銑に吹き付けて溶銑脱燐を行うに際し、より効果的に脱燐処理効率を向上させることのできる溶銑の処理方法を提供することにある。 The present invention has been made in view of the above-mentioned problems, and its problem is to improve the dephosphorization efficiency more effectively when the hot metal dephosphorization is performed by spraying the hot iron with a dephosphorizing agent on the hot metal. An object of the present invention is to provide a hot metal treatment method that can be used.
本発明者らは、上述の課題を解決するために、溶銑の脱燐処理能率や脱燐反応効率を向上させる方法を検討し、下記の（ａ）〜（ｅ）の知見を得て、本発明を完成させた。 In order to solve the above-mentioned problems, the present inventors have studied a method for improving the dephosphorization efficiency of hot metal and the dephosphorization reaction efficiency, and obtained the following knowledge (a) to (e). Completed the invention.
（ａ）脱珪処理した溶銑を転炉型脱燐炉にて脱燐処理するに際して、脱珪スラグを除去せずに、または脱珪スラグを一部除去した後の溶銑を転炉型脱燐炉内に装入することにより、適切量の溶銑脱珪スラグを溶銑とともに転炉型脱燐炉内に供給する方法を採用すると、脱燐剤の上吹きによる脱燐に先立って転炉型脱燐炉内にカバースラグが形成され、脱燐反応が効果的に進行する。 (A) When dephosphorizing the desiliconized hot metal in a converter type dephosphorization furnace, the hot metal after removing the desiliconized slag without removing the desiliconized slag is converted into the converter type dephosphorization. If a method of supplying an appropriate amount of hot metal desiliconized slag along with hot metal into the converter dephosphorization furnace by charging it into the furnace, the converter type degassing prior to dephosphorization by blowing up the dephosphorizing agent is adopted. Cover slag is formed in the phosphorus furnace, and the dephosphorization reaction proceeds effectively.
（ｂ）上記（ａ）における脱珪剤としては、転炉における脱炭精錬により生成したスラグ（以下、「転炉脱炭スラグ」とも記す）を用いることが好ましい。転炉脱炭スラグ中に含有されるＣａＯ、ＦｅＯ成分などを有効に利用できるからである。 (B) As the desiliconizing agent in the above (a), it is preferable to use slag generated by decarburization refining in a converter (hereinafter also referred to as “converter decarburization slag”). This is because CaO, FeO components and the like contained in the converter decarburization slag can be used effectively.
（ｃ）溶銑中Ｓｉ含有率が高く、その結果、脱珪量が多くなる場合には、スラグ生成量が増大するので、ある程度の除滓を行ってから、脱珪処理後の溶銑とともに転炉型脱燐炉に装入するのが好ましい。これに対して、溶銑中Ｓｉ含有率が低く、その結果、脱珪量が少ない場合、または転炉脱炭スラグを利用して脱珪スラグ量を増大させた場合には、脱珪スラグを除滓せずに脱珪処理後の溶銑とともに転炉型脱燐炉に装入するのが好ましい。以下、このような脱珪方法を「調整脱珪法」ともいう。 (C) When the Si content in the hot metal is high and, as a result, the amount of desiliconization increases, the amount of slag generated increases. It is preferable to charge the mold dephosphorization furnace. On the other hand, when the Si content in the hot metal is low and, as a result, the amount of desiliconization is small, or when the amount of desiliconization slag is increased using converter decarburization slag, the desiliconization slag is removed. It is preferable to charge the converter dephosphorization furnace together with the hot metal after the desiliconization treatment without dripping. Hereinafter, such a desiliconization method is also referred to as an “adjusted desiliconization method”.
（ｄ）上記（ｃ）の調整脱珪法は、スラグ生成量の調整の容易さ、およびスラグ生成後の温度低下によるスラグの固化を避ける観点から、転炉型脱燐炉への溶銑装入の直前に行うことが好ましい。具体的には、トーピードカーから溶銑鍋への溶銑払い出しの際に、溶銑の払い出し流に巻き込まれるように脱珪剤を必要量投入するか、または溶銑払い出し前に溶銑鍋に脱珪剤を必要量装入しておく方法が好適である。 (D) The adjustment desiliconization method of (c) above is the method of adjusting the amount of slag produced and charging the molten iron into the converter dephosphorization furnace from the viewpoint of avoiding the solidification of the slag due to the temperature drop after slag production. It is preferable to carry out immediately before. Specifically, when the hot metal is discharged from the torpedo car to the hot metal ladle, the required amount of desiliconizing agent is introduced so as to be caught in the hot metal discharge flow, or the required amount of desiliconizing agent is added to the hot metal pan before the hot metal is discharged. A method of charging is preferred.
（ｅ）上記（ａ）〜（ｄ）の方法により脱燐処理を行った後、脱炭精錬の前に行う脱硫処理は、脱硫効率の高い機械攪拌式脱硫法によることが好ましい。 (E) The desulfurization treatment performed after the dephosphorization treatment by the above methods (a) to (d) and before the decarburization refining is preferably performed by a mechanical stirring type desulfurization method having high desulfurization efficiency.
本発明は上記の知見に基づいて完成されたものであり、その要旨とするところは下記の（１）〜（４）に示す溶銑の処理方法にある。 The present invention has been completed based on the above findings, and the gist of the present invention resides in the hot metal treatment method shown in the following (1) to (4).
（１）高炉から出銑後に脱珪処理前の溶銑中Ｓｉ含有率が０．２５〜０．４０質量％の溶銑を脱珪処理し、その溶銑を転炉型脱燐炉にて脱燐処理するに際して、前記脱珪処理をトーピードカーから溶銑鍋への溶銑払出しの際に脱珪剤を投入する方法により行うか、またはその払出しに先立って該溶銑鍋に脱珪剤を装入しておく方法により行うか、または前記の両方法により行い、かつ、前記脱珪処理した溶銑を、該溶銑が収容された溶銑鍋から転炉型脱燐炉に装入する前に、前記脱珪処理における脱珪量を０．０５質量％以上とし、その後、該脱珪処理により生成したスラグを該溶銑鍋から除去することなく、転炉型脱燐炉に装入し、ＣａＯを含有する粉状の脱燐剤を上吹きランスから酸素をキャリアガスとして該溶銑に吹き付けることにより脱燐処理を行うことを特徴とする溶銑の処理方法。
ここで、脱珪量は、（高炉出銑時の溶銑中Ｓｉ含有率の分析値（質量％））−（脱珪処理終了後の溶銑中Ｓｉ含有率の分析値（質量％））により求められる値を指す。
（２）高炉から出銑後に脱珪処理前の溶銑中Ｓｉ含有率が０．２０質量％以下の溶銑を脱珪処理し、その溶銑を転炉型脱燐炉にて脱燐処理するに際して、該溶銑が収容された溶銑鍋から転炉型脱燐炉に装入する前に、脱珪処理によって脱珪量を０．０５〜０．１０質量％とし、該脱珪処理により生成したスラグを該溶銑鍋から除去することなく、転炉型脱燐炉に装入し、ＣａＯを含有する粉状の脱燐剤を上吹きランスから酸素をキャリアガスとして該溶銑に吹き付けることにより脱燐処理を行うことを特徴とする溶銑の処理方法。
(1) Hot metal with a Si content of 0.25 to 0.40 mass% in the hot metal after leaving the blast furnace and before desiliconization is desiliconized , and the hot metal is dephosphorized in a converter dephosphorization furnace. The desiliconization process is performed by a method of adding a desiliconizing agent at the time of discharging the hot metal from the torpedo car to the hot metal ladle, or a method of charging the hot metal pan prior to the discharge carried out by performing or the both methods by and said desiliconization treated hot metal, prior to charged into the converter type dephosphorization furnace from hot metal pot solution pig iron is accommodated, de in the desiliconization treatment The amount of silicon is set to 0.05% by mass or more, and then the slag generated by the desiliconization treatment is charged into the converter dephosphorization furnace without removing from the hot metal ladle, and the powdered degassing containing CaO is performed. By spraying the phosphor from the top lance with oxygen as the carrier gas. Processing method of hot metal and performing dephosphorization.
Here, the amount of silicon removal is determined by (analyzed value of Si content in hot metal at the time of blast furnace discharge (mass%))-(analyzed value of Si content in hot metal after completion of desiliconization treatment (mass%)). Points to the resulting value.
(2) When the hot metal having a Si content of 0.20% by mass or less after the removal from the blast furnace and before the desiliconization treatment is desiliconized , and the molten iron is dephosphorized in a converter dephosphorization furnace , before charging the converter type dephosphorization furnace from hot metal pan in which the hot metal is housed, de珪量and 0.05-0.10 mass% by desiliconization treatment, the slag produced by the dehydration silicofluoride treatment Without removing from the hot metal ladle, the dephosphorization treatment was performed by charging the hot metal into a converter type dephosphorization furnace and spraying a powdered dephosphorization agent containing CaO from the top blowing lance to the hot metal with oxygen as a carrier gas. A method for treating hot metal, which is performed.
（３）前記脱珪処理を、トーピードカーから溶銑鍋への溶銑払出しの際に脱珪剤を投入する方法により行うか、またはその払出しに先立って該溶銑鍋に脱珪剤を装入しておく方法により行うか、または前記の両方法により行う前記（２）に記載の溶銑の処理方法。 (3) The desiliconization process is carried out by a method of adding a desiliconizing agent when the hot metal is discharged from the torpedo car to the hot metal ladle, or prior to the discharge, the desiliconizing agent is charged into the hot metal pan. hot metal treatment process according to prior SL (2) to perform or not to perform the method, or by both methods described above.
（４）前記脱珪処理に用いる脱珪剤として、転炉による脱炭スラグ以外の酸化鉄源と脱炭スラグとを添加量の合計で３〜１５ｋｇ／ｔ用いる前記（２）または（３）に記載の溶銑の処理方法。 (4) Examples de珪剤used for desiliconization treatment, said the Ru used 3~15kg / t of iron oxide source and the decarburization slag other than decarburization slag by BOF in total amount (2) or (3 ) .
（５）高炉から出銑後に脱珪処理した溶銑を、転炉型脱燐炉にて脱燐処理した後に溶銑鍋に出湯し、該溶銑鍋において該溶銑を機械攪拌式脱硫法により脱硫処理し、次いで転炉にて該溶銑を脱炭精錬する前記（１）〜（４）のいずれか１項に記載の溶銑の処理方法。 (5) The hot metal that has been desiliconized after being discharged from the blast furnace is dephosphorized in a converter dephosphorization furnace, then poured into a hot metal ladle, and the hot metal is desulfurized by a mechanical stirring desulfurization method in the hot metal ladle. Then, the hot metal treatment method according to any one of (1) to (4), wherein the hot metal is decarburized and refined in a converter.
本発明において、「転炉型脱燐炉」とは、脱燐剤などの粉体を上吹きランスにより溶銑に吹き付けて脱燐処理を行うことのできる充分なフリーボード（上部空間）を有する転炉形式の脱燐炉を意味し、溶銑をガス攪拌するための底吹き機構を有することが好ましい。 In the present invention, the “converter-type dephosphorization furnace” is a converter having a sufficient free board (upper space) capable of performing dephosphorization treatment by spraying powder such as a dephosphorizing agent on hot metal with an upper blowing lance. It means a furnace type dephosphorization furnace, and preferably has a bottom blowing mechanism for gas stirring of the molten iron.
「粉状の脱燐剤」とは、酸素ガスにより搬送および吹き付けが可能な粉状または粒状の脱燐剤を意味する。好ましくは、粒径が１００メッシュ以下（１４７μｍ以下）の微粉により構成される脱燐剤が例示できるが、粒径が３ｍｍ以下の粗粒が含まれていてもよい。 The “powdered dephosphorizing agent” means a powdery or granular dephosphorizing agent that can be conveyed and sprayed by oxygen gas. Preferably, a dephosphorizing agent composed of fine powder having a particle size of 100 mesh or less (147 μm or less) can be exemplified, but coarse particles having a particle size of 3 mm or less may be included.
そして、「機械攪拌式脱硫法」とは、溶銑中に浸漬した攪拌翼を回転させて溶銑を攪拌しながら脱硫する脱硫方法を意味し、例えば、ＫＲ脱硫法などが該当する。また、本明細書の記載において、「スラグの一部を除去」とは、溶銑鍋内に、溶銑１トン（ｔ）当たりスラグを２ｋｇ以上残すようにスラグを除去（以下、「除滓」とも記す）することを意味する。 The “mechanical stirring type desulfurization method” means a desulfurization method in which the stirring blade immersed in the hot metal is rotated to desulfurize the hot metal while stirring. For example, the KR desulfurization method is applicable. In the description of the present specification, “removing part of the slag” means removing slag so as to leave 2 kg or more of slag per ton (t) of hot metal in the hot metal ladle (hereinafter referred to as “removal”). It means).
なお、以下の説明において、含有率についての「％」の標記は、「質量％」を意味するものとする。 In the following description, the symbol “%” for the content rate means “mass%”.
本発明の溶銑の処理方法によれば、脱珪処理前の溶銑中Ｓｉ含有率が０．２５〜０．４０質量％の溶銑を脱珪処理し、その溶銑を転炉型脱燐炉にて脱燐処理するに際して、前記脱珪処理をトーピードカーから溶銑鍋への溶銑払出しの際に脱珪剤を投入する方法により行うか、またはその払出しに先立って該溶銑鍋に脱珪剤を装入しておく方法により行うか、または前記の両方法により行い、かつ、前記脱珪処理を行った溶銑を、溶銑鍋から転炉型脱燐炉に装入する前に、前記脱珪処理における脱珪量を０．０５質量％以上とし、その後、脱珪スラグを除去することなく、転炉型脱燐炉に装入し、脱燐剤を上吹きランスから酸素をキャリアガスとして溶銑に吹き付けるので、スラグの滓化が向上するとともに、カバースラグが迅速かつ確実に形成され、脱燐処理能率および脱燐反応効率を向上させることができる。 According to the hot metal treatment method of the present invention, the hot metal having a Si content in the hot metal before desiliconization of 0.25 to 0.40% by mass is desiliconized, and the hot metal is converted into a converter dephosphorization furnace. When performing the dephosphorization treatment, the desiliconization treatment is performed by a method in which a desiliconizing agent is introduced when the hot metal is discharged from the torpedo car to the hot metal pan, or prior to the discharge, the desiliconizing agent is charged into the hot metal pan. or by a method previously, or carried out by both methods described above, and the molten pig iron subjected to the desiliconization treatment, prior to charged into the converter type dephosphorization furnace from molten iron pan, desiliconization in the desiliconization treatment The amount is set to 0.05% by mass or more, and after that, without removing the desiliconization slag, it is charged into the converter type dephosphorization furnace, and the dephosphorizing agent is blown into the hot metal using oxygen as a carrier gas from the top blowing lance. The slag hatching is improved and the cover slag is shaped quickly and reliably. Is, it is possible to improve the dephosphorization efficiency and dephosphorization reaction efficiency.
本発明は、前記したとおり、高炉から出銑後に脱珪処理前の溶銑中Ｓｉ含有率が０．２５〜０．４０質量％の溶銑を脱珪処理し、その溶銑を転炉型脱燐炉にて脱燐処理するに際して、前記脱珪処理をトーピードカーから溶銑鍋への溶銑払出しの際に脱珪剤を投入する方法により行うか、またはその払出しに先立って該溶銑鍋に脱珪剤を装入しておく方法により行うか、または前記の両方法により行い、かつ、前記脱珪処理した溶銑を、該溶銑が収容された溶銑鍋から転炉型脱燐炉に装入する前に、前記脱珪処理における脱珪量を０．０５質量％以上とし、その後、該脱珪処理により生成したスラグを該溶銑鍋から除去することなく、転炉型脱燐炉に装入し、ＣａＯを含有する粉状の脱燐剤を上吹きランスから酸素をキャリアガスとして該溶銑に吹き付けることにより脱燐処理を行う溶銑の処理方法である。以下に、本発明の方法についてさらに詳細に説明する。
In the present invention, as described above, the hot metal having an Si content of 0.25 to 0.40 % by mass in the hot metal after being discharged from the blast furnace is desiliconized , and the hot metal is converted into a converter dephosphorization furnace. In the dephosphorization process, the desiliconization process is performed by a method of adding a desiliconizing agent when discharging the hot metal from the torpedo car to the hot metal pan, or prior to the discharge, the desiliconizing agent is installed in the hot metal pan. or by a method to keep entering or carried out by both methods described above, and said desiliconization treated hot metal, prior to charged into the converter type dephosphorization furnace from hot metal pot solution pig iron is received, the de珪量in desiliconization treated with 0.05 wt% or more, then, the slag generated by the desiliconization treatment without removal from the solution pig iron pot, was charged into a converter type dephosphorization furnace, containing CaO A powdered dephosphorizing agent is blown over the lance and oxygen is used as a carrier gas. A hot metal processing method for performing dephosphorization by blowing. Hereinafter, the method of the present invention will be described in more detail.
１．基礎となる技術的思想
本発明において、転炉型脱燐炉での溶銑脱燐処理前に行う溶銑脱珪処理は、その処理場所に特に限定されない。例えば、高炉出銑樋内、トーピードカー内、溶銑鍋内などにおいて、周知の方法により行うことができる。但し、本発明における溶銑脱珪処理の目的が、溶銑中のＳｉ含有率の調整とともに、転炉型脱燐炉内で行う粉体上吹き脱燐に先立って該脱燐炉内に供給するカバースラグの生成にあることにおいて、従来の溶銑脱珪プロセスとは大きく相違する。従来の溶銑脱珪プロセスにおいては、その目的は、溶銑脱燐時の脱燐効率を高めるため、および脱燐スラグの生成量を低減するために、脱燐炉へ持込まれるＳｉ源を低減することにあったからである。したがって、脱珪処理において生成したスラグは、転炉への持込みを避けるために、溶銑を転炉に装入する前に、極力完全に除去されていた。
1. Technical idea that serves as a basis In the present invention, the hot metal dephosphorization treatment performed before the hot metal dephosphorization treatment in the converter type dephosphorization furnace is not particularly limited to the treatment place. For example, it can be carried out by a well-known method in a blast furnace tuna, a torpedo car, a hot metal ladle or the like. However, the purpose of the hot metal desiliconization treatment in the present invention is to cover the Si content in the hot metal and to supply the powder into the dephosphorization furnace prior to the powder top blowing dephosphorization performed in the converter dephosphorization furnace. In the production of slag, it is greatly different from the conventional hot metal desiliconization process. The purpose of the conventional hot metal desiliconization process is to reduce the Si source brought into the dephosphorization furnace in order to increase the dephosphorization efficiency during hot metal dephosphorization and to reduce the amount of dephosphorization slag produced. Because it was. Therefore, the slag generated in the desiliconization process has been completely removed as much as possible before charging the hot metal into the converter in order to avoid bringing it into the converter.
しかし、本発明では、適切な量の溶銑脱珪スラグを転炉型脱燐炉内に持ち込むことが、脱珪処理の主たる目的の一つである。転炉型脱燐炉に持ち込まれるＳｉ源の総量は、従来の溶銑脱珪処理と同様に、ある程度の適正範囲にコントロールすることが望ましいが、それとともに重視すべき点は、「適正量の脱珪スラグを転炉型脱燐炉に供給すること」である。つまり、粉体上吹き脱燐に先立って転炉型脱燐炉内にカバースラグを供給し、溶銑装入後に、可及的速やかに粉体状脱燐剤を上吹きする脱燐（以下、「粉体上吹き脱燐」とも記す）を開始できるように炉内の吹錬条件を整えることである。 However, in the present invention, bringing an appropriate amount of hot metal desiliconization slag into the converter dephosphorization furnace is one of the main purposes of the desiliconization treatment. The total amount of Si source brought into the converter dephosphorization furnace is desirably controlled within a certain range as in the conventional hot metal desiliconization process. "To supply silica slag to the converter dephosphorization furnace". In other words, prior to the powder top blowing dephosphorization, the cover slag is supplied into the converter type dephosphorization furnace, and the dephosphorization (hereinafter referred to as “powder dephosphorization”) is performed as soon as possible after the hot metal is charged. (Also referred to as “powder-on-powder dephosphorization”) so that the blowing conditions in the furnace can be adjusted.
この場合、溶銑脱珪量のみならず、投入する脱珪剤の種類や量によっても、溶銑脱珪スラグの生成量および成分組成が異なる。従来の脱珪処理では、Ｓｉの酸化のために気体酸素や酸化鉄が主として用いられ、その脱珪反応時に起こるスラグフォーミングを抑制するために生石灰などのＣａＯ源が補助的に用いられていた。しかし、本発明の脱珪処理では、転炉型脱燐炉に持ち込む脱珪スラグの生成をも目的とすることから、細かく破砕した転炉脱炭スラグを脱珪剤として適時に用い、脱炭スラグ中に含有されるＣａＯやＦｅＯを有効に利用することができる。表１に脱珪剤として用いる転炉脱炭スラグの成分組成および粒径を例示する。 In this case, not only the amount of hot metal desiliconization but also the amount and component composition of hot metal desiliconization slag differ depending on the type and amount of the desiliconizing agent to be added. In the conventional desiliconization treatment, gaseous oxygen or iron oxide is mainly used for the oxidation of Si, and a CaO source such as quick lime is used auxiliary to suppress slag forming that occurs during the desiliconization reaction. However, in the desiliconization treatment of the present invention, the purpose is also to generate desiliconization slag to be brought into the converter type dephosphorization furnace. Therefore, the finely crushed converter decarburization slag is used as a desiliconizing agent in a timely manner. CaO and FeO contained in the slag can be used effectively. Table 1 illustrates the component composition and particle size of converter decarburization slag used as a desiliconizing agent.
例えば、溶銑中Ｓｉ含有率が低目であるために、脱燐効率向上の面から溶銑中のＳｉ含有率を低下させる必要がない場合には、高炉原料としての焼結鉱や圧延時に生成するスケールなどからなる少量の酸化剤とともに転炉脱炭スラグを適当量用いると、溶銑中Ｓｉの酸化とともに、塩基度（ＣａＯ／ＳｉＯ2）が１〜２の範囲の比較的低塩基度の半溶融スラグが必要量生成されるので、好適である。転炉脱炭スラグとして、溶銑脱燐後の溶銑を脱炭精錬する際に生成するスラグを用いると、Ｐ含有率が低く、かつＴ.Ｆｅ含有率が高いので、特に好ましい。 For example, when the Si content in the hot metal is low and it is not necessary to reduce the Si content in the hot metal from the viewpoint of improving the dephosphorization efficiency, it is generated during sintering or rolling as a blast furnace raw material. When an appropriate amount of converter decarburization slag is used together with a small amount of oxidizer consisting of scale, etc., the basicity (CaO / SiO 2 ) is a semi-molten with a relatively low basicity in the range of 1-2, along with oxidation of Si in the hot metal. Since the required amount of slag is generated, it is preferable. As the converter decarburization slag, use of slag produced when decarburizing and refining the hot metal after hot metal dephosphorization is particularly preferable because the P content is low and the T.Fe content is high.
この溶銑脱珪スラグの除滓および転炉型脱燐炉への装入は、下記のとおり行うのが好ましい。すなわち、溶銑中Ｓｉ含有率が高く、その結果、脱珪量が多くなる場合には、スラグ生成量が増大するので、ある程度の除滓を行ってから、脱珪処理後の溶銑とともに転炉型脱燐炉に装入するのが好ましい。これに対して、溶銑中Ｓｉ含有率が低く、その結果、脱珪量が少ない場合または転炉脱炭スラグを利用して脱珪スラグ量を増大させた場合には、脱珪スラグを除滓せずに脱珪処理後の溶銑とともに転炉型脱燐炉に装入するのが好ましい。 The removal of the hot metal desiliconized slag and the charging into the converter dephosphorization furnace are preferably performed as follows. That is, when the Si content in the hot metal is high and, as a result, the amount of desiliconization increases, the slag generation amount increases. It is preferable to charge in a dephosphorization furnace. On the other hand, when the Si content in the hot metal is low and, as a result, the amount of desiliconization is small or when the amount of desiliconization slag is increased using converter decarburization slag, the desiliconization slag is removed. Instead, it is preferable to charge the converter dephosphorization furnace together with the hot metal after the desiliconization treatment.
上記のようにして行う調整脱珪法は、スラグ生成量の調整の容易さ、およびスラグ生成後の温度低下によるスラグの固化を避けるために、転炉型脱燐炉への溶銑装入の直前に行うことが好ましい。具体的には、トーピードカーから溶銑鍋への溶銑払い出しの際に、溶銑の払い出し流に巻き込まれるように脱珪剤を必要量投入するか、または溶銑払い出し前に溶銑鍋に脱珪剤を必要量装入しておく方法が好ましい。なお、溶銑中Ｓｉ含有率が高い場合には、必要に応じて溶銑鍋から生成スラグを除去するが、溶銑中Ｓｉ含有率が低く、生成スラグを除去する必要がない場合には、溶銑および生成した脱珪スラグを一緒に転炉型脱燐炉に装入すればよい。 The adjustment desiliconization method performed as described above is performed immediately before the molten iron is charged into the converter type dephosphorization furnace in order to prevent the slag production from being easily adjusted and to prevent the slag from solidifying due to a temperature drop after the slag production. It is preferable to carry out. Specifically, when the hot metal is discharged from the torpedo car to the hot metal ladle, the required amount of desiliconizing agent is introduced so as to be caught in the hot metal discharge flow, or the required amount of desiliconizing agent is added to the hot metal pan before the hot metal is discharged. The method of charging is preferred. In addition, when the Si content in hot metal is high, the generated slag is removed from the hot metal pan as needed, but when the Si content in the hot metal is low and it is not necessary to remove the generated slag, hot metal and generation What is necessary is just to charge the desiliconized slag together into a converter type dephosphorization furnace.
２．好適な実施態様
本発明の溶銑の処理方法を実施するに際しての好ましい態様および好ましい範囲について下記に説明する。
2. Preferred Embodiments Preferred embodiments and preferred ranges for carrying out the hot metal treatment method of the present invention will be described below.
（１）脱珪量
高炉から出銑された溶銑をトーピードカーから溶銑鍋に移す際の溶銑の落下流に、例えば焼結鉱などの酸化鉄含有物質からなる脱珪剤を投入することにより脱珪処理を施すのが好ましい。ここで、考慮しなければならないのは、脱珪剤の量である。
(1) Amount of desiliconization Desiliconization is achieved by introducing a desiliconization agent made of iron oxide-containing material such as sintered ore into the molten iron falling flow when the molten iron discharged from the blast furnace is transferred from the torpedo car to the hot metal ladle. It is preferable to apply the treatment. Here, it is the amount of the desiliconizing agent that must be considered.
図１は、高炉から出銑された溶銑中のＳｉ含有率が０．２５〜０．４０％の場合における脱燐率と脱珪量との関係を示す図である。同図の結果から、脱珪量が０．０５％以上となるように脱珪剤の量を調整すれば、８０％以上の脱燐率が得られ、好ましいことがわかる。上記の脱珪量は、生成ＳｉＯ2量では１．２（ｋｇ／ｔ−溶銑）以上に相当し、さらにＳｉＯ2以外の他成分の存在も考慮すると、生成スラグ量では２（ｋｇ／ｔ−溶銑）以上に相当する。 FIG. 1 is a diagram showing the relationship between the dephosphorization rate and the desiliconization amount when the Si content in the hot metal discharged from the blast furnace is 0.25 to 0.40%. From the results shown in the figure, it can be seen that if the amount of the desiliconization agent is adjusted so that the desiliconization amount is 0.05% or more, a dephosphorization rate of 80% or more is obtained, which is preferable. The above silicon removal amount corresponds to 1.2 (kg / t-molten metal) or more in the amount of generated SiO 2 , and further considering the presence of other components other than SiO 2 , the amount of generated slag is 2 (kg / t--). It corresponds to the above.
ここで、脱珪量とは、（高炉出銑時の溶銑中Ｓｉ含有率の分析値（％））−（脱珪処理終了後の溶銑中Ｓｉ含有率の分析値（％））を指す。また、脱燐率とは、｛（脱珪処理終了後の溶銑中Ｐ含有率の分析値（％））−（脱燐処理後に転炉型脱燐炉から溶銑鍋に出湯した際の鍋中における溶銑中Ｐ含有率の分析値（％））｝／（脱珪処理終了後の溶銑中Ｐ含有率の分析値（％））×１００（％）を意味する。 Here, the amount of silicon removal refers to (analyzed value of Si content in hot metal at the time of blast furnace discharge (%)) − (analyzed value of Si content in hot metal after completion of desiliconization treatment (%)). The dephosphorization rate is {(analytical value of P content in hot metal after completion of desiliconization treatment (%))-(in the pan when the hot water is discharged from the converter type dephosphorization furnace to the hot metal ladle after the dephosphorization process. Analytical value of P content in hot metal (%))} / (Analyzed value of P content in hot metal after desiliconization treatment (%)) × 100 (%).
ただし、溶銑中Ｓｉ含有率が低い場合には、脱珪量を一定値以下の範囲に抑えることが好ましい。図２は、溶銑中Ｓｉ含有率が０．２０％以下の場合における脱燐率と脱珪量との関係を示す図である。同図の結果からわかるように、溶銑中Ｓｉ含有率が０．２０％以下の場合には、脱珪量が０．０８％を超えて多くなると脱燐率が低下することから、脱珪量を０．０５〜０．１０％程度にしておくことが好ましい。 However, when the Si content in the hot metal is low, it is preferable to keep the desiliconization amount within a certain value or less. FIG. 2 is a diagram showing the relationship between the dephosphorization rate and the desiliconization amount when the Si content in the hot metal is 0.20% or less. As can be seen from the results in the figure, when the Si content in the hot metal is 0.20% or less, the dephosphorization rate decreases when the desiliconization amount exceeds 0.08%. Is preferably about 0.05 to 0.10%.
これは、溶銑中Ｓｉ含有率が低い場合に０．０８％を超える脱珪を行うと、溶銑中のＳｉ含有率の低下により、転炉型脱燐炉での脱燐精錬時にＳｉの酸化発熱量が減少し、スラグ量の確保を目的として投入したＳｉＯ2を含有する副原料が完全に溶融し切らず、その結果、溶融スラグ量が減少して脱燐不良が発生する可能性が高くなるからである。 This is because, when the silicon content in the hot metal is low, if desiliconization exceeding 0.08% is performed, due to the decrease in the Si content in the hot metal, the heat of oxidation of Si occurs during dephosphorization in the converter dephosphorization furnace. As a result, the amount of the auxiliary material containing SiO 2 introduced for the purpose of securing the amount of slag is not completely melted. As a result, the amount of molten slag is reduced and the possibility of dephosphorization failure is increased. Because.
（２）脱燐処理
脱珪スラグを除滓せずに、溶銑を脱珪スラグとともに転炉型脱燐炉に装入し、ＣａＯを含有する粉状の脱燐剤を上吹きランスから酸素をキャリアガスとして溶銑に吹き付けて脱燐処理を行う。ＣａＯを含有する粉状脱燐剤としては、石灰石を焼成して得られる生石灰の粉砕物（ＣａＯ含有率が９０％以上で、焼成残りのＣａＣＯ3や石灰石の脈石として含有されるＭｇＯなどを含む）のほか、石灰石単味やドロマイト（ＣａＣＯ3・ＭｇＣＯ3）などの一般的な製鋼用副原料の粉砕物が例示される。
(2) Dephosphorization treatment Without removing the desiliconization slag, the molten iron was charged into the converter type dephosphorization furnace together with the desiliconization slag, and a powdered dephosphorization agent containing CaO was blown from the top lance with oxygen. Dephosphorization is performed by spraying hot metal as a carrier gas. As the powdered dephosphorizing agent containing CaO, limestone pulverized product obtained by firing limestone (CaO content of 90% or more, CaCO 3 remaining after firing, MgO contained as limestone gangue, etc.) In addition, pulverized products of common raw materials for steel making such as limestone and dolomite (CaCO 3 · MgCO 3 ) are also exemplified.
石灰石や製鋼用副原料の粉砕には工業的に知られた破砕方法を適宜用いればよく、粉状脱燐剤の粒子径は、酸素ガスによって搬送および吹付けが可能な大きさであればよい。具体的には、１００メッシュ以下などの微粉が例示されるが、粒径が３ｍｍ以下の粗粒が含まれていても構わない。 An industrially known crushing method may be appropriately used for pulverization of limestone and steelmaking auxiliary materials, and the particle size of the powdered dephosphorizing agent may be any size that can be conveyed and sprayed by oxygen gas. . Specifically, fine powder such as 100 mesh or less is exemplified, but coarse particles having a particle size of 3 mm or less may be included.
上記の粉体上吹き脱燐処理に際して、特許文献３に記載された方法のように、転炉型脱燐炉への溶銑の装入前にＣａＯを含有する副原料を脱燐炉内に前装入したり、または溶銑装入後にＣａＯ含有副原料を溶銑上に上置きしたりすると、それらによるスピッティング抑制効果と相俟って、本発明法の効果が一層顕著となる。ＣａＯを含有する副原料としては、生石灰や石灰石、ドロマイトのほか、転炉スラグ、取鍋スラグなどが例示される。 In the above-described powder blown dephosphorization treatment, as in the method described in Patent Document 3, before the molten iron is charged into the converter type dephosphorization furnace, the auxiliary material containing CaO is put in the dephosphorization furnace. If the CaO-containing auxiliary raw material is placed on the hot metal after charging or hot metal charging, the effect of the method of the present invention becomes more remarkable in combination with the effect of suppressing spitting. Examples of the auxiliary material containing CaO include quick lime, limestone, and dolomite, converter slag, ladle slag, and the like.
同じＳｉ含有率を有する溶銑で比較すると、事前に脱珪処理を行った場合の方が、上吹きランスから吹き付けられたＣａＯ粉が火点において、ＣａＯ−ＳｉＯ2−ＦｅＯ系化合物よりも脱燐能の高いＣａＯ−ＦｅＯ系化合物を形成しやすいので、火点での脱燐反応が起きやすく、高い脱燐能が得られると考えられる。また、ＣａＯを含有する副原料を脱燐炉内に前装入するか、または溶銑装入後に上置きした場合は、脱珪処理時に生成した低融点のＳｉＯ2−ＦｅＯ系化合物によりＣａＯ含有副原料の溶融が促進され、スラグの滓化率が向上する結果、安定した高い脱燐能が得られる。 When compared with hot metal having the same Si content, when desiliconization is performed in advance, the CaO powder sprayed from the top blowing lance is dephosphorized compared to the CaO—SiO 2 —FeO-based compound at the fire point. Since a high-performance CaO—FeO-based compound is easily formed, it is considered that a dephosphorization reaction easily occurs at a fire point, and a high dephosphorization ability is obtained. In addition, when the auxiliary material containing CaO is pre-charged in the dephosphorization furnace or placed after the molten iron is charged, the CaO-containing auxiliary material is generated by the low melting point SiO 2 —FeO-based compound generated during the desiliconization process. As a result of promoting the melting of the raw material and improving the hatching rate of the slag, a stable and high dephosphorization ability is obtained.
一般に、ＣａＯ粉などを上吹きする溶銑の粉体上吹き脱燐方法では、ＣａＯ粉の吹き付けに起因してスピッティングが増加する傾向にあり、上吹きランスへの地金の付着や鉄分ロスの増加などの問題が発生する可能性が高い。しかし、本発明の溶銑処理方法のように、脱珪スラグが溶銑表面に存在する条件下においては、溶銑表面を覆うカバースラグが迅速かつ確実に形成されるので、スピッティングの抑制に対しても著しい効果が発揮される。 In general, in the hot metal powder top dephosphorization method that blows up CaO powder and the like, spitting tends to increase due to the spraying of CaO powder. There is a high possibility that problems such as increase will occur. However, under the conditions where desiliconized slag is present on the hot metal surface as in the hot metal treatment method of the present invention, the cover slag that covers the hot metal surface is formed quickly and reliably, so that it is possible to suppress spitting. A remarkable effect is exhibited.
具体的には、従来技術として前述した特許文献３に記載された溶銑の脱燐方法では、スピッティングの発生を防止するために、カバースラグの生成工程として３分間を要していたのに対して、本発明法のように転炉型脱燐炉への溶銑装入前に、好ましくは２ｋｇ／ｔ以上の所定量のスラグを生成させておく場合には、カバースラグの生成工程は１分間程度で充分である。それ故、粉状のＣａＯ含有脱燐剤を溶銑に吹き付ける本来の脱燐工程の時間を２分間長く確保できることが判明した。この場合、脱燐剤供給量の原単位（ｋｇ／ｔ）が同じ条件下では、本来の脱燐時間が延長されているので、脱燐剤の単位時間当たりの供給速度（ｋｇ／ｔ／ｍｉｎ）は相対的に減少している。その結果、粉状脱燐剤が火点においてＣａＯ−ＦｅＯ系化合物になりやすく、かつ、そのＣａＯ−ＦｅＯ系化合物と溶銑中の燐との反応機会が多くなるので、１回の脱燐処理当たりの脱燐率は向上していると考えられる。 Specifically, in the hot metal dephosphorization method described in Patent Document 3 described above as the prior art, it took 3 minutes as a cover slag generation process to prevent spitting. In the case where a predetermined amount of slag of 2 kg / t or more is preferably generated before hot metal charging into the converter dephosphorization furnace as in the present invention method, the cover slag generation process takes 1 minute. The degree is sufficient. Therefore, it has been found that the original dephosphorization step of spraying the powdered CaO-containing dephosphorizing agent on the hot metal can ensure a long time of 2 minutes. In this case, since the original dephosphorization time is extended under the same conditions for the basic unit (kg / t) of the dephosphorizing agent supply amount, the dephosphorizing agent supply rate per unit time (kg / t / min) ) Is relatively decreasing. As a result, the powdered dephosphorizing agent is likely to become a CaO—FeO compound at the point of fire, and there are many opportunities for reaction between the CaO—FeO compound and phosphorus in the hot metal, so that per dephosphorization treatment. It is considered that the dephosphorization rate is improved.
（３）調整脱珪および除滓の省略
本願発明における調整脱珪処理の効果は、溶銑中のＳｉ含有率の適度の低下効果に、さらにスピッティングを抑制するためのカバースラグの生成工程の短縮効果、すなわち、粉体上吹き時間の延長効果が重畳されたものであるから、高炉出銑時の溶銑中Ｓｉ含有率が低い場合には、脱珪効果よりもカバースラグの生成効果の方が大きくなる。
(3) Omission of adjustment desiliconization and removal of iron The effect of the adjustment desiliconization treatment in the present invention is due to the moderate reduction effect of the Si content in the hot metal and the shortening of the cover slag generation process for further suppressing spitting. The effect, i.e., the effect of extending the powder blowing time is superimposed, so if the Si content in the hot metal at the time of blast furnace discharge is low, the cover slag generation effect is better than the desiliconization effect. growing.
現実に、脱炭スラグ以外の酸化鉄源による計算上の脱珪量を０.０５％未満に抑えて、脱炭スラグ中のＦｅＯ成分などによる脱珪およびスラグの生成を図った結果、脱炭スラグ以外の酸化鉄源と脱炭スラグとの添加量の合計が３ｋｇ／ｔ以上の範囲において、溶銑中Ｓｉ含有率が０．２０％以下で脱珪量が０．０２〜０．０５％であっても脱燐率が８０％以上となる安定的な脱燐率の向上が見られた。同様に、溶銑中Ｓｉ含有率が低い溶銑を脱珪後に脱燐した図２で示される試験の場合には、脱珪量が０．０２〜０．０５％の範囲では、脱燐率は７０〜７７％程度であったが、その脱珪剤には通常の焼結鉱を用いていた。それに対して、脱炭スラグを併用する調整脱珪法を利用した場合には、脱珪に用いた脱炭スラグの滓化効果が溶銑の脱燐率向上に寄与し、安定的に脱燐率が向上したものと考えられる。 Actually, decalcification and generation of slag with FeO components in decarburized slag, while reducing the calculated desiliconization amount by iron oxide sources other than decarburized slag to less than 0.05%. When the total amount of the iron oxide source other than slag and the decarburized slag is 3 kg / t or more, the Si content in the hot metal is 0.20% or less and the desiliconization amount is 0.02 to 0.05%. Even in such a case, a stable improvement of the dephosphorization rate was seen in which the dephosphorization rate was 80% or more. Similarly, in the case of the test shown in FIG. 2 in which hot metal having a low Si content in hot metal was dephosphorized after desiliconization, the dephosphorization rate was 70 when the desiliconization amount was in the range of 0.02 to 0.05%. Although it was about ˜77%, ordinary sinter was used as the desiliconizing agent. On the other hand, when the adjusted desiliconization method using decarburization slag is used, the hatching effect of the decarburization slag used for desiliconization contributes to the improvement of the dephosphorization rate of hot metal, and the dephosphorization rate is stable. Is considered to have improved.
上記の酸化鉄源と脱炭スラグとの添加合計量は、一層安定した効果を得る観点からは、５ｋｇ／ｔ以上とすることが好ましいが、一方では、添加合計量の必要以上の増加は、脱燐炉への持込みスラグ量を増加させ、脱燐スラグ量の増加をきたす。したがって、脱燐スラグ量の生成抑制効果を勘案すると、この添加合計量は１５ｋｇ／ｔ以下とすることが好ましい。 From the viewpoint of obtaining a more stable effect, the total amount of the iron oxide source and the decarburized slag is preferably 5 kg / t or more. The amount of slag brought into the dephosphorization furnace is increased, and the amount of dephosphorization slag is increased. Therefore, considering the effect of suppressing the amount of dephosphorization slag, the total amount added is preferably 15 kg / t or less.
さらに、除滓は、脱珪処理を行った後、次工程の処理前に実施されるのが一般的であることから、この除滓により、スラグとともに溶銑の一部が流出して鉄歩留りが低下したり、除滓時に溶銑温度が低下したり、さらには、除滓に時間を要するため本来の脱燐時間が短縮されるなどの問題が発生する。これに対して、本発明の溶銑処理方法では、除滓を省略するか、または一部の除滓しか行わないため、これらの問題を大幅に解消できる。 Furthermore, since the removal is generally performed after the silicon removal treatment and before the next process, a part of the molten iron flows out together with the slag and the iron yield is reduced. There arises a problem that the temperature is lowered, the temperature of the hot metal is lowered at the time of removal, and further, the time required for removal is reduced, so that the original dephosphorization time is shortened. On the other hand, in the hot metal treatment method of the present invention, since removal is omitted or only partial removal is performed, these problems can be greatly solved.
ここで、一部の除滓とは、前記したとおり、溶銑鍋内にスラグを２ｋｇ／ｔ以上残すような除滓を意味する。 Here, as described above, part of the demolition means demolition that leaves 2 kg / t or more of slag in the hot metal ladle.
（４）脱硫工程を含めた態様
本発明の溶銑の処理方法は、熱力学的に有利な条件、すなわち脱硫後に脱燐処理を行う下記のプロセス（ａ）においてよりも、熱力学的には不利な条件、すなわち脱燐の後に脱硫処理を行うプロセス（ｂ）において適用する方が、より一層著しい効果を発揮する。
(4) Aspect Including Desulfurization Step The hot metal treatment method of the present invention is thermodynamically less favorable than the thermodynamically advantageous condition, that is, the following process (a) in which dephosphorization is performed after desulfurization. The effect is more remarkable when applied in the condition (b) in which the desulfurization treatment is performed after the dephosphorization.
（ａ）高炉出銑→脱硫処理→脱珪処理→脱燐処理→脱炭処理
（ｂ）高炉出銑→脱珪処理→脱燐処理→脱硫処理→脱炭処理
それは、前記したとおり、脱珪処理した溶銑を脱燐処理するに際して、適切量の溶銑脱珪スラグを転炉型脱燐炉内に持ち込むことにより、脱燐処理に先立ってカバースラグが形成され、脱燐反応が効率的に進行すること、さらには、脱珪剤として転炉脱炭スラグを用いることにより、脱炭スラグ中に含有されるＣａＯ、ＦｅＯ成分などが有効利用できることなどにより、脱燐処理効率を向上させることができ、これらが、熱力学的に不利な条件を相殺して、なお余りある効果を奏するからである。
(A) Blast furnace discharge → Desulfurization process → Desiliconization process → Dephosphorization process → Decarburization process (b) Blast furnace output → Desiliconization process → Dephosphorization process → Desulfurization process → Decarburization process When dephosphorizing the treated hot metal, an appropriate amount of hot metal desiliconized slag is brought into the converter type dephosphorization furnace, so that cover slag is formed prior to the dephosphorization process, and the dephosphorization reaction proceeds efficiently. In addition, by using converter decarburization slag as a desiliconizing agent, CaO, FeO components, etc. contained in the decarburization slag can be effectively used, and the dephosphorization efficiency can be improved. This is because these still cancel out the disadvantages of thermodynamics and still have a more advantageous effect.
これに対して、プロセス（ａ）において脱珪スラグを脱燐炉に持ち込むためには、脱硫処理後に脱硫スラグを除滓した後、脱珪処理を行う必要がある。この場合には、脱硫スラグを完全に除滓することは困難であり、脱珪処理時に、残留した脱硫スラグから溶銑への復硫が発生するので、安定した溶銑の低硫化は難しい。 On the other hand, in order to bring the desiliconized slag into the dephosphorization furnace in the process (a), it is necessary to remove the desulfurized slag after the desulfurization and then perform the desiliconization. In this case, it is difficult to completely remove the desulfurized slag and, since desulfurization from the remaining desulfurized slag to the hot metal occurs during the desiliconization process, it is difficult to stably reduce the sulfur of the hot metal.
近年では、鋼の低硫化および低燐化の要求が極めて強くなっており、低硫鋼を安定して溶製できることがプロセスの必須条件となっている。この点において、プロセス（ｂ）において優れた効果を発揮できる本発明の溶銑処理方法は、工業的利用価値が高い。 In recent years, the demand for low sulfidation and low phosphatization of steel has become extremely strong, and it is an essential condition of the process that low-sulfur steel can be stably melted. In this respect, the hot metal treatment method of the present invention that can exhibit an excellent effect in the process (b) has a high industrial utility value.
本発明の方法において、脱燐処理後に行う脱硫処理の方法は特に限定されないが、脱硫効率が高く、かつ操業安定性に優れた機械攪拌式脱硫法によることが好ましい。ここで、機械攪拌式脱硫法とは、溶銑中に浸漬した攪拌翼を回転させて溶銑を攪拌しながら脱硫する脱硫方法を意味し、例えば、ＫＲ脱硫法などがこれに該当する。 In the method of the present invention, the method of desulfurization treatment performed after the dephosphorization treatment is not particularly limited, but it is preferable to use a mechanical stirring type desulfurization method having high desulfurization efficiency and excellent operational stability. Here, the mechanical stirring type desulfurization method means a desulfurization method in which the stirring blade immersed in the hot metal is rotated to desulfurize the hot metal while stirring, for example, the KR desulfurization method.
本発明の溶銑の処理方法の効果を確認するため、高炉から出銑された溶銑を用いて下記に述べる試験を行い、その結果を評価した。 In order to confirm the effect of the hot metal processing method of the present invention, the test described below was performed using the hot metal discharged from the blast furnace, and the result was evaluated.
（試験方法）
高炉から出銑された溶銑２６４トン（ｔ）をトーピードカー（混銑車）から溶銑鍋に注銑し、その際に、下記の表２に示す成分組成を有する焼結鉱を脱珪剤として投入し、脱珪処理を行った。
(Test method)
264 tons (t) of hot metal discharged from the blast furnace is poured into a hot metal ladle from a torpedo car (mixed car), and at that time, sintered ore having the composition shown in Table 2 below is added as a desiliconizing agent. Then, desiliconization treatment was performed.
このとき、一部の試験では、トーピードカーから溶銑鍋への溶銑の払い出し（注銑）に先立って溶銑鍋に脱珪剤を装入する方法を採用し、また、一部の試験では、Ｓｉ含有率の低い溶銑を対象とし、脱珪剤として前記表１に記載した成分組成と粒径を有する転炉脱炭スラグおよび焼結鉱を用いる方法を採用した。なお、試験した範囲では、トーピードカーから溶銑鍋に注銑する際に焼結鉱を投入する方法と、トーピードカーから溶銑鍋への注銑に先立って溶銑鍋に脱珪剤を装入する方法とでは、脱珪および脱燐ともに有意差は見られなかった。 At this time, in some tests, a method of inserting a desiliconizing agent into the hot metal ladle prior to the discharge (injection) of the hot metal from the torpedo car to the hot metal ladle is adopted. For hot metal having a low rate, a method using a converter decarburization slag having a component composition and particle size described in Table 1 and a sintered ore as a desiliconizing agent was employed. In addition, within the range tested, the method of charging sintered ore when pouring from the torpedo car to the hot metal ladle and the method of charging the hot metal ladle with the desiliconizing agent prior to pouring from the torpedo car to the hot metal ladle There was no significant difference between desiliconization and dephosphorization.
続いて、上記の脱珪後の溶銑を、脱珪スラグを除滓せずにそのまま、スクラップ２９ｔまたはスクラップ２９ｔと表３に示される成分組成を有する取鍋スラグ７ｋｇ／ｔとを装入した上底吹き転炉に装入し、炉底に設置された羽口からＮ2ガスを吹き込みながら、生石灰粉を溶銑に吹き付けて脱燐処理を行った。 Subsequently, the hot metal after desiliconization was charged with scrap 29t or scrap 29t and ladle slag 7 kg / t having the composition shown in Table 3 without removing the desiliconized slag. The reactor was charged into a bottom-blown converter, and dephosphorization was performed by blowing quick lime powder onto the hot metal while N 2 gas was blown from the tuyere installed at the bottom of the furnace.
ここで、炉底羽口からのＮ2ガス吹込量は０．２７Ｎｍ3／（ｍｉｎ・ｔ）とし、また、溶銑への生石灰粉の吹き付けは、３孔ストレートノズルを有する上吹きランスから、１．４Ｎｍ3／（ｍｉｎ・ｔ）の流量の酸素とともに、１００メッシュ以下（１００メッシュ篩下）の粒度を有する生石灰粉（ＣａＯ含有率：９５％）を溶銑に吹き付ける方法を採用した。また、装入ＳｉＯ2量が９．０ｋｇ／ｔ以上となるように、珪石（ＳｉＯ2含有率：９５％）の装入量を調整し、スラグの装入塩基度を約１．７とした。 Here, the amount of N 2 gas blown from the furnace bottom tuyere was 0.27 Nm 3 / (min · t), and quick lime powder was blown onto the hot metal from an upper blowing lance having a three-hole straight nozzle. A method of spraying quick lime powder (CaO content: 95%) having a particle size of 100 mesh or less (under 100 mesh sieve) on hot metal together with oxygen at a flow rate of .4 Nm 3 / (min · t) was adopted. Further, the amount of silica (SiO 2 content: 95%) was adjusted so that the amount of SiO 2 charged was 9.0 kg / t or more, and the basicity of slag was about 1.7. .
このとき、一部の試験では、脱珪処理後の溶銑から脱珪スラグの一部を除去（除滓）し、その溶銑を残りの脱珪スラグとともに上底吹き転炉に装入し、上記と同様の方法により脱燐処理を行った。 At this time, in some tests, a part of the desiliconized slag was removed from the molten iron after the desiliconization treatment (the removal), and the molten iron was charged into the top bottom blowing converter together with the remaining desiliconized slag. The dephosphorization process was performed by the same method.
表４に、各試験についての脱珪処理および脱燐処理条件を示した。 Table 4 shows desiliconization treatment and dephosphorization treatment conditions for each test.
試験番号１〜１２は、本発明で規定する条件を満足する本発明例についての試験であり、試験番号１３〜２１は、脱珪処理しない溶銑を脱燐処理した比較例についての試験である。 Test Nos. 1 to 12 are tests for examples of the present invention that satisfy the conditions defined in the present invention, and Test Nos. 13 to 21 are tests for comparative examples in which hot metal that has not been desiliconized is dephosphorized.
ここで、試験番号１０は、前記したとおり、脱珪処理後の溶銑から脱珪スラグの一部を除滓した後、その溶銑を残りの脱珪スラグ３ｋｇ／ｔとともに脱燐処理を行った試験であり、試験番号１１は、トーピードカーから溶銑鍋への溶銑の払い出しに先立って溶銑鍋に脱珪剤を装入した試験であり、また、試験番号１２は、Ｓｉ含有率の低い溶銑を対象とし、脱珪剤として、転炉脱炭スラグ４．０ｋｇ／ｔおよび焼結鉱１．０ｋｇ／ｔを用いた試験である。 Here, test number 10 is a test in which, as described above, after removing a part of desiliconized slag from the molten iron after desiliconization, the molten iron was dephosphorized together with the remaining 3 kg / t of desiliconized slag. Test number 11 is a test in which a desiliconizing agent is charged into the hot metal ladle prior to the discharge of the hot metal from the torpedo car to the hot metal ladle, and test number 12 is for hot metal with a low Si content. In this test, 4.0 kg / t of converter decarburization slag and 1.0 kg / t of sintered ore were used as a desiliconizing agent.
脱燐処理時における上底吹き転炉での酸素上吹き時間は全て９分間とし、上吹き酸素のみによりカバースラグを生成する時間を試験番号１〜１７では１分間とし、試験番号１８〜２１では２分間とした。 The oxygen top blowing time in the top bottom blowing converter at the time of dephosphorization is all 9 minutes, the time for generating cover slag by only top blowing oxygen is 1 minute in test numbers 1 to 17, and in test numbers 18 to 21 2 minutes.
なお、表４において、脱珪前の溶銑中Ｓｉ含有率は、高炉出銑時の採取サンプルについてのＳｉ分析値を採取した。 In Table 4, for the Si content in the hot metal before desiliconization, the Si analysis value for the sample collected at the time of blast furnace discharge was collected.
（試験結果）
前記表４に、脱珪処理および脱燐処理についての試験結果を併せて示した。本発明で規定する条件を満足する本発明例の試験である試験番号１〜１２では、脱珪処理の行われていない溶銑を脱燐処理した比較例の試験である試験番号１３〜２１に比較して高い脱燐率が得られており、本発明法による脱燐処理効率の向上効果が明確に現れている。
(Test results)
Table 4 also shows the test results for the desiliconization treatment and the dephosphorization treatment. Test Nos. 1 to 12, which are tests of the present invention that satisfy the conditions specified in the present invention, are compared with Test Nos. 13 to 21, which are tests of comparative examples in which hot metal that has not been desiliconized is dephosphorized. Thus, a high dephosphorization rate is obtained, and the effect of improving the dephosphorization efficiency by the method of the present invention clearly appears.
上記の試験結果をさらに、取鍋スラグを脱燐用の上底吹き転炉に前装入しなかった本発明例の試験番号１〜５と比較例の試験番号１３〜１７との比較、および、取鍋スラグを脱燐用の上底吹き転炉に前装入した本発明例の試験番号６〜９と比較例の試験番号１８〜１２１との比較を行うことにより詳細に検討した。 The above test results were further compared with the test numbers 1 to 5 of the present invention example and the test numbers 13 to 17 of the comparative examples in which the ladle slag was not pre-charged into the top bottom blowing converter for dephosphorization, and The ladle slag was examined in detail by comparing the test numbers 6 to 9 of the present invention example in which the ladle slag was pre-charged into the top bottom blowing converter for dephosphorization and the test numbers 18 to 121 of the comparative example.
図３は、脱燐炉内に取鍋スラグを装入しない場合における脱珪前溶銑中Ｓｉ含有率と脱燐率との関係を、本発明例および比較例について比較した図であり、図４は、脱燐炉内に取鍋スラグを装入した場合での脱珪前溶銑中Ｓｉ含有率と脱燐率との関係を、本発明例および比較例について比較した図である。 FIG. 3 is a diagram comparing the relationship between the Si content in the hot metal before desiliconization and the dephosphorization rate when the ladle slag is not charged in the dephosphorization furnace for the present invention example and the comparative example. These are the figures which compared the example of this invention and the comparative example about the relationship between Si content rate in the hot metal before desiliconization, and the dephosphorization rate when ladle slag is inserted in the dephosphorization furnace.
図３および図４の結果から、脱燐炉内に取鍋スラグを装入した場合も装入しなかった場合も、溶銑中Ｓｉ含有率の値によらず、本発明例の試験では、比較例の試験に比べて脱燐率が５％程度高く、８０％以上の水準となっていることがわかる。 From the results of FIG. 3 and FIG. 4, whether or not the ladle slag was charged into the dephosphorization furnace, in the test of the example of the present invention, regardless of the value of the Si content in the hot metal, the comparison was made. It can be seen that the dephosphorization rate is about 5% higher than the test of the example, which is a level of 80% or more.
また、脱珪スラグの一部を除滓した後、その溶銑を残りの脱珪スラグとともに脱燐処理した試験番号１０、トーピードカーから溶銑鍋への溶銑の払い出しに先立って溶銑鍋に脱珪剤を装入した試験番号１１、および、脱珪剤として転炉脱炭スラグと焼結鉱とを用いた試験番号１２においても、比較例に比べて高い脱燐率が得られ、脱燐効率の向上が確認された。 In addition, after removing a part of the desiliconized slag, the molten iron was dephosphorized together with the remaining desiliconized slag, test number 10, prior to the discharge of the molten iron from the torpedo car to the hot metal ladle, Test No. 11 charged and Test No. 12 using converter decarburization slag and sintered ore as a desiliconizing agent also provided a higher dephosphorization rate than the comparative example and improved dephosphorization efficiency. Was confirmed.
試験番号１３〜１７では粉体上吹き開始以後２分間程度、スピッティングが継続的に観察された。これに対して、本発明例である試験番号１〜１２、および比較例において取鍋スラグを装入した試験番号１８〜２１ではスピッティングは全く観察されず、スピッティング抑制効果が確認された。 In Test Nos. 13 to 17, spitting was continuously observed for about 2 minutes after the start of powder blowing. On the other hand, spitting was not observed at all in Test Nos. 1 to 12, which are examples of the present invention, and Test Nos. 18 to 21 in which the ladle slag was charged in the comparative example, and the effect of suppressing spitting was confirmed.
本発明の溶銑の処理方法によれば、脱珪処理した溶銑から脱珪スラグを除去することなく、または脱珪スラグの一部を除去した後に、転炉型脱燐炉に装入し、脱燐剤を上吹きランスから酸素をキャリアガスとして溶銑に吹き付けるので、スラグの滓化が向上するとともに、カバースラグが迅速かつ確実に形成され、脱燐処理能率および脱燐反応効率を向上させることができる。したがって、本発明の方法は、脱珪処理、脱燐処理および脱硫処理を含めた溶銑の予備処理工程において、合理的かつ経済的プロセスとして広範に適用できる。 According to the hot metal treatment method of the present invention, without removing the desiliconized slag from the desiliconized hot metal or after removing a part of the desiliconized slag, the molten iron is charged into the converter type dephosphorization furnace, Since the phosphorus agent is blown from the top blowing lance to the hot metal using oxygen as a carrier gas, the hatching of the slag is improved and the cover slag is formed quickly and reliably, improving the dephosphorization efficiency and the dephosphorization reaction efficiency. it can. Therefore, the method of the present invention can be widely applied as a rational and economical process in the hot metal pretreatment process including desiliconization, dephosphorization and desulfurization.
Claims (5)
ここで、脱珪量は、（高炉出銑時の溶銑中Ｓｉ含有率の分析値（質量％））−（脱珪処理終了後の溶銑中Ｓｉ含有率の分析値（質量％））により求められる値を指す。 In the hot metal in the Si content of the pre desiliconization treatment from a blast furnace after tapping is Desiliconization handling hot metal 0.25 to 0.40 wt%, to dephosphorization process the molten iron in a converter furnace type dephosphorization furnace, Whether the desiliconization treatment is performed by a method of adding a desiliconizing agent when discharging the hot metal from the torpedo car to the hot metal ladle, or by a method of loading the desiliconizing agent in the hot metal pan prior to the discharge or performed by the both methods described above, and the molten iron was the desiliconization treatment, prior to charged into the converter type dephosphorization furnace from hot metal pot solution pig iron is housed, de珪量in the desiliconization treatment 0.05 mass % or more, and then, without removing the slag produced by the desiliconization treatment from the hot metal ladle, it was charged into a converter dephosphorization furnace, and a powdered dephosphorization agent containing CaO was added. Dephosphorization is achieved by spraying oxygen on the hot metal from the top blowing lance as a carrier gas. Processing method of hot metal and performing management.
Here, the amount of silicon removal is determined by (analyzed value of Si content in hot metal at the time of blast furnace discharge (mass%))-(analyzed value of Si content in hot metal after completion of desiliconization treatment (mass%)). Points to the resulting value.
ここで、脱珪量は、（高炉出銑時の溶銑中Ｓｉ含有率の分析値（質量％））−（脱珪処理終了後の溶銑中Ｓｉ含有率の分析値（質量％））により求められる値を指す。 In the hot metal in the Si content of the pre desiliconization treatment from a blast furnace after tapping is 0.20 mass% or less of molten iron and desiliconization treatment and dephosphorization processes the hot metal in a converter furnace type dephosphorization furnace, the molten iron is Before charging the molten iron ladle contained in the converter dephosphorization furnace, the desiliconization amount is set to 0.05 to 0.10 mass % by desiliconization treatment, and the slag generated by the desiliconization treatment is converted into the hot metal ladle. Without removing it from the furnace, it is charged into a converter type dephosphorization furnace, and a dephosphorization treatment is performed by spraying a powdered dephosphorization agent containing CaO from the top blowing lance to the molten iron using oxygen as a carrier gas. A feature of the hot metal treatment method.
Here, the amount of silicon removal is determined by (analyzed value of Si content in hot metal at the time of blast furnace discharge (mass%))-(analyzed value of Si content in hot metal after completion of desiliconization treatment (mass%)). Points to the resulting value.
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| JP5282539B2 (en) * | 2008-11-18 | 2013-09-04 | 新日鐵住金株式会社 | Hot phosphorus dephosphorization method |
| JP2011012286A (en) * | 2009-06-30 | 2011-01-20 | Sumitomo Metal Ind Ltd | Method for dephosphorizing molten iron |
| JP2011122214A (en) * | 2009-12-11 | 2011-06-23 | Sumitomo Metal Ind Ltd | Method for dephosphorizing molten iron |
| JP2011179041A (en) * | 2010-02-26 | 2011-09-15 | Sumitomo Metal Ind Ltd | Method for removing metal in converter |
| KR101702247B1 (en) | 2012-06-18 | 2017-02-03 | 제이에프이 스틸 가부시키가이샤 | Refining method and molten steel production method |
| BR112016001198B1 (en) * | 2013-07-25 | 2020-10-13 | Jfe Steel Corporation | method for dephosphorization process of cast iron |
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| JP6375822B2 (en) * | 2014-09-22 | 2018-08-22 | 新日鐵住金株式会社 | Hot metal desiliconization method |
| JP6460265B2 (en) * | 2016-01-15 | 2019-01-30 | 新日鐵住金株式会社 | Converter blowing method |
| JP2017128749A (en) * | 2016-01-18 | 2017-07-27 | 新日鐵住金株式会社 | Desiliconization method of molten iron |
| CN111670258B (en) * | 2018-03-07 | 2023-01-10 | 日本制铁株式会社 | Method for dephosphorizing molten iron |
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| CN104419798B (en) * | 2013-09-05 | 2017-02-22 | 鞍钢股份有限公司 | Method for pre-desiliconizing molten iron by utilizing CAS-OB refining furnace |
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