JPH0885811A - Method for refining molten chromium-containing steel - Google Patents
Method for refining molten chromium-containing steelInfo
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- JPH0885811A JPH0885811A JP22538194A JP22538194A JPH0885811A JP H0885811 A JPH0885811 A JP H0885811A JP 22538194 A JP22538194 A JP 22538194A JP 22538194 A JP22538194 A JP 22538194A JP H0885811 A JPH0885811 A JP H0885811A
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- refining
- gas
- vacuum
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- molten
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、含クロム溶鋼の脱炭処
理後の還元処理において、高価なＡｒガスの使用量を抑
え、効率的に処理を行う含クロム溶鋼の精錬法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for refining molten chromium-containing steel, which efficiently reduces the amount of expensive Ar gas used in the reduction treatment after decarburization of molten chromium-containing steel.
【０００２】[0002]
【従来の技術】従来、ステンレス鋼のごとき１１ｍａｓ
ｓ％以上のクロムを含むような含クロム溶鋼の精錬法と
しては、浴面下より酸素ガスまたは酸素ガス（以下、単
に酸素という）と不活性ガスの混合ガスを吹込むＡＯＤ
法が広く用いられている。ＡＯＤ法は脱炭が進行し、溶
鋼中の〔Ｃ〕濃度が低下してくると〔Ｃｒ〕が酸化され
やすくなることから、〔Ｃ〕濃度の低下に伴い吹込みガ
ス中のＡｒガスやＮ2 ガスのような不活性ガスの比率を
高くし、酸素の比率を低くして〔Ｃｒ〕の酸化を抑える
方法がとられている。しかし、該方法でも〔Ｃｒ〕の酸
化が進行するため、目標〔Ｃ〕濃度まで脱炭した後に、
酸化した〔Ｃｒ〕を回収するために不活性ガスのみを吹
込みながら、ＳｉやＡｌ等の還元剤を添加して処理する
還元処理を行っている。2. Description of the Related Art Conventionally, 11mas such as stainless steel
As a refining method for molten chromium-containing steel containing s% or more of chromium, AOD in which oxygen gas or a mixed gas of oxygen gas (hereinafter simply referred to as oxygen) and an inert gas is blown from below the bath surface
The method is widely used. In the AOD method, when decarburization progresses and [C] concentration in molten steel decreases, [Cr] is easily oxidized. Therefore, as the [C] concentration decreases, Ar gas and N in the blown gas are reduced. A method of suppressing the oxidation of [Cr] by increasing the ratio of an inert gas such as 2 gas and decreasing the ratio of oxygen is adopted. However, since the oxidation of [Cr] proceeds even in this method, after decarburization to the target [C] concentration,
In order to recover the oxidized [Cr], a reducing treatment is performed in which a reducing agent such as Si or Al is added while blowing only an inert gas.
【０００３】含クロム溶鋼は、多量に含まれる〔Ｃｒ〕
が溶鋼中の〔Ｎ〕の活量を大幅に低下させるために、
〔Ｎ〕の溶解度が大きく、不活性ガスとしてＮ2 ガスの
みを吹込んだ場合には〔Ｎ〕濃度は０．２ｍａｓｓ％以
上にもなる。特殊な鋼種を除き、一般的な製品に要求さ
れる〔Ｎ〕濃度は０．１ｍａｓｓ％以下であり、このた
め、ＡＯＤ法では脱炭の初期を除き、不活性ガスとして
高価なＡｒガスを使用する必要があり、経済的に不利に
なっていた。Chromium-containing molten steel is contained in a large amount [Cr].
In order to significantly reduce the activity of [N] in the molten steel,
The solubility of [N] is large, and when only N 2 gas is blown as the inert gas, the [N] concentration becomes 0.2 mass% or more. Except for special steel types, the [N] concentration required for general products is 0.1 mass% or less. Therefore, in the AOD method, expensive Ar gas is used as the inert gas except in the initial stage of decarburization. Had to be economically disadvantaged.
【０００４】このような問題点を解決する方法として、
特開平４−２１４８６号公報および特開平４−２６３０
０５号公報記載の方法が提案されている。これらの含ク
ロム溶鋼の精錬方法は、同一精錬容器を用いて、〔Ｃ〕
濃度０．２〜０．０５ｍａｓｓ％までは吹込みガスとし
てＮ2 ガスを主体とした非酸化性ガスと酸素の混合ガス
を使用し、〔Ｃ〕濃度がこの範囲内に低下した後は、２
００〜１５Ｔｏｒｒに減圧し、かつ吹込みガスとしてＮ
2 ガスを主体とした非酸化性ガスのみを使用し、目標
〔Ｃ〕濃度までの脱炭を行い、その後、吹込みガスをＡ
ｒガスとして、酸化した〔Ｃｒ〕を回収するために還元
剤を添加して処理する方法である。これらの方法によ
り、脱炭精錬ではＡｒガスを使用する必要はなくなる
が、還元処理はＡｒガスの使用が必須であるため、効率
的な精錬とは言えなかった。As a method of solving such a problem,
JP-A-4-21486 and JP-A-4-2630
The method described in Japanese Patent Publication No. 05 has been proposed. The refining methods for these molten chromium-containing steels are carried out by using the same refining vessel [C].
A mixed gas of a non-oxidizing gas mainly composed of N 2 gas and oxygen is used as a blowing gas up to a concentration of 0.2 to 0.05 mass%, and after the [C] concentration falls within this range, 2
The pressure is reduced to 00 to 15 Torr, and N is used as a blowing gas.
Using only non-oxidizing gas consisting mainly of 2 gases, decarburization up to the target [C] concentration, and then blowing gas to A
This is a method in which a reducing agent is added and treated to recover oxidized [Cr] as r gas. By these methods, it is not necessary to use Ar gas in decarburization refining, but it cannot be said to be efficient refining because use of Ar gas is essential for reduction treatment.
【０００５】一方、脱炭精錬に二酸化炭素ガス（以下、
ＣＯ2 という）使用する方法としては、例えば特開昭５
５−１５８２０８号公報には、酸素上吹き製鋼法におい
て浴面下よりＣＯ2 を吹込み、溶鋼の攪拌を促進させて
脱炭を促進させる方法が記載されている。また、特開昭
５７−３２３１６号公報には転炉において鋼浴下部の羽
口より酸素とともにＣＯ2 を吹込み、ＣＯ2 の冷却効果
を利用して羽口の溶損を防止する方法が記載されてい
る。これらの方法では、ＣＯ2 は完全にＣＯとＯに分解
するとしており、この考え方では還元処理時にＣＯ2 を
使用すれば酸化反応が進行するため、十分な効果は得ら
れない。On the other hand, carbon dioxide gas (hereinafter,
As a method of using (for example, CO 2 ), for example, Japanese Patent Laid-Open No.
Japanese Patent Laid-Open No. 5-158208 describes a method in which CO 2 is blown from below the bath surface in the oxygen top blowing steelmaking method to promote stirring of molten steel and promote decarburization. Further, describes a process for preventing the erosion of blowing a CO 2 oxygen with than steel bath bottom tuyeres, by utilizing the cooling effect of the CO 2 tuyeres in the converter in JP-A-57-32316 Has been done. According to these methods, CO 2 is said to be completely decomposed into CO and O, and in this concept, if CO 2 is used during the reduction treatment, the oxidation reaction proceeds, so that a sufficient effect cannot be obtained.
【０００６】また、特開昭５０−３７６１１号公報に
は、ＣＯ2 は分解せず、ＣＯの希釈効果をもつためにＡ
ｒガスのような不活性ガスの代替として使用する方法が
記載されているが、この方法ではＣＯ2 のＣＯとＯへの
分解率が定量化されておらず、真空下で使用した場合の
反応挙動も不明であるため、過剰な不活性ガスを使用す
る結果となって十分な効果が得られない。Further, in Japanese Patent Laid-Open No. 503761/1999, CO 2 is not decomposed and has a CO diluting effect.
A method of using it as a substitute for an inert gas such as r gas has been described, but the decomposition rate of CO 2 into CO and O is not quantified by this method, and the reaction when used under vacuum is described. Since the behavior is also unclear, a sufficient effect cannot be obtained as a result of using excess inert gas.
【０００７】[0007]
【発明が解決しようとする課題】本発明は、同一精錬容
器を用いて大気圧精錬後、真空精錬を用いる含クロム溶
鋼の精錬法において、還元処理時に高価なＡｒガスに換
えて、安価なＣＯ2 の使用を可能とする効率的な精錬法
を提供することを目的とするものである。DISCLOSURE OF THE INVENTION According to the present invention, in the refining method of molten chromium-containing steel using vacuum refining after refining at atmospheric pressure using the same refining vessel, inexpensive CO gas is used instead of expensive Ar gas during reduction treatment. The purpose of the present invention is to provide an efficient refining method that enables the use of 2 .
【０００８】[0008]
【課題を解決するための手段】本発明は、上述の課題を
有利に解決したものであり、その要旨とするところは下
記のとおりである。 （１）同一の精錬容器を用いて大気圧下での脱炭処理
後、真空下での脱炭および還元処理を行う含クロム溶鋼
の精錬法において、前記還元処理を溶鋼トン当り０．２
Ｎｍ3 ／ｍｉｎ以上の二酸化炭素ガスを吹込みながら真
空度１００Ｔｏｒｒ以下の真空下で行うことを特徴とす
る含クロム溶鋼の精錬法。The present invention advantageously solves the above-mentioned problems, and the gist thereof is as follows. (1) In a refining method for molten chromium-containing steel, which comprises decarburizing treatment under atmospheric pressure using the same refining vessel, and then performing decarburizing and reducing treatment under vacuum, the reduction treatment is performed at 0.2 per ton of molten steel.
A refining method for molten chromium-containing steel, which is performed under a vacuum of 100 Torr or less while blowing carbon dioxide gas of Nm 3 / min or more.
【０００９】（２）同一の精錬容器を用いて大気圧下で
の脱炭処理後、還元処理のみを真空下で行うことを特徴
とする前項（１）記載の含クロム溶鋼の精錬法。以下に
本発明について詳細に説明する。本発明の含クロム溶鋼
の精錬方法は、図１に例示するような精錬方法である。
精錬容器１内で含クロム溶鋼４中に底吹き羽口２を通し
て精錬ガス５を吹込む。また、精錬容器１は脱着可能な
排気フード３を有しており、任意の真空度までの減圧が
可能である。本発明法の精錬では、精錬のはじめは排気
フード３のない状態で大気圧精錬を行い、その後排気フ
ード３を装着し、真空引きを開始して真空精錬を行う方
法である。(2) The method for refining molten chromium-containing steel according to the above (1), characterized in that the same refining vessel is used for decarburization at atmospheric pressure and then only the reduction is performed under vacuum. The present invention will be described in detail below. The refining method for molten chromium-containing steel of the present invention is a refining method as illustrated in FIG.
The refining gas 5 is blown into the molten chromium-containing steel 4 in the refining vessel 1 through the bottom blowing tuyere 2. Further, the refining vessel 1 has a detachable exhaust hood 3 and can reduce the pressure to an arbitrary degree of vacuum. In the refining of the method of the present invention, atmospheric refining is performed without the exhaust hood 3 at the beginning of refining, then the exhaust hood 3 is attached, vacuuming is started, and vacuum refining is performed.
【００１０】また、本発明は、含クロム溶鋼の精錬にお
いて、吹込んだＣＯ2 の下記式および式による分解
反応は真空度の低下および吹込みガス流量の増大により
抑制することが可能であり、式および式の反応が進
行しなければＣＯ2 はＡｒガスやＮ2 ガスと同等の不活
性ガスとしての作用があることを見出し、この作用を還
元処理に利用することにより、効率的な精錬法を提供す
るものである。Further, according to the present invention, in refining molten chromium-containing steel, the decomposition reaction of the injected CO 2 according to the following equation and the equation can be suppressed by lowering the degree of vacuum and increasing the flow rate of the blowing gas, It was found that CO 2 acts as an inert gas equivalent to Ar gas or N 2 gas if the reaction of the formula and the formula does not proceed, and by utilizing this action for reduction treatment, an efficient refining method Is provided.
【００１１】 ＣＯ2 （ｇ）＝ＣＯ（ｇ）＋１／２Ｏ2 （ｇ）…… ＣＯ2 （ｇ）＝〔Ｃ〕＋Ｏ2 （ｇ）………………… 図２にＳＵＳ３０４ステンレス鋼を同一精錬容器を用い
て大気圧精錬後、真空精錬を実施した場合の還元処理時
に真空度を１００Ｔｏｒｒ以下とし、ＣＯ2 を吹込んだ
場合のＣＯ2 の流量とＣＯ2 反応率の関係を示す。な
お、ＣＯ2 反応率は吹込みＣＯ2 １Ｎｍ3 に対してＯ2
１Ｎｍ3 が発生した場合を１００とした比率である。図
２より、ＣＯ2 流量が溶鋼トン当り０．２Ｎｍ3 ／ｍｉ
ｎ以上ではＣＯ2 反応率は低位に安定し、吹込んだＣＯ
2 のほとんどがＡｒガス等の不活性ガスと同等の作用を
もつことが確認された。CO 2 (g) = CO (g) + 1 / 2O 2 (g) …… CO 2 (g) = [C] + O 2 (g) …………………… Fig. 2 shows SUS304 stainless steel. after atmospheric pressure refining with the same refining vessel, the degree of vacuum not more than 100Torr upon reduction process when carried out vacuum refining, showing the relationship between the flow rate and the CO 2 reactivity of the CO 2 in the case that crowded blowing the CO 2. Incidentally, CO 2 reaction rate O 2 with respect to the blow CO 2 1 Nm 3
The ratio is 100 when 1 Nm 3 is generated. From Fig. 2, the CO 2 flow rate is 0.2 Nm 3 / mi per ton of molten steel.
Above n, the CO 2 reaction rate stabilizes at a low level, and the injected CO
It was confirmed that most of 2 have the same action as an inert gas such as Ar gas.
【００１２】図３にＳＵＳ３０４ステンレス鋼を同一精
錬容器を用いて大気圧精錬後、真空精錬を実施した場合
の還元処理時に溶鋼トン当り０．２Ｎｍ3 ／ｍｉｎ以上
のＣＯ2 を吹込んだ時の処理時の真空度とＣＯ2 反応率
の関係を示す。図３より、真空度１００Ｔｏｒｒ以下で
はＣＯ2 の反応は低位に安定し、吹込んだＣＯ2 のほと
んどがＡｒガス等の不活性ガスと同等の作用をもつこと
が確認された。FIG. 3 shows that when SUS304 stainless steel was subjected to atmospheric pressure refining using the same refining vessel and then vacuum refining was performed, CO 2 of 0.2 Nm 3 / min or more per ton of molten steel was blown during reduction treatment. The relationship between the degree of vacuum during processing and the CO 2 reaction rate is shown. From FIG. 3, it was confirmed that at a vacuum degree of 100 Torr or less, the reaction of CO 2 was stable at a low level, and most of the injected CO 2 had the same action as an inert gas such as Ar gas.
【００１３】以上より、本発明法に従えば、同一精錬容
器を用いて大気圧精錬後、真空精錬を行う精錬法におい
て、還元処理時に従来分解反応による酸化反応の進行が
懸念されていたＣＯ2 の使用が可能になり、効率的な精
錬が行える。また、真空精錬は鋼種によっては脱炭精錬
の不要な鋼種もあるが、この場合には還元精錬のみを真
空下で行えば、効率的な精錬が可能になる。なお、ＣＯ
2 流量が溶鋼トン当り０．２Ｎｍ3 ／ｍｉｎに近く、か
つ真空度が１００Ｔｏｒｒに近い場合には若干のＣＯ2
の分解反応が進行し、分解したＯ2 による酸化が進行す
るが、図２および図３に示されているように反応率が小
さいために問題はない。また、ＣＯ2 反応率も定量化さ
れているため、酸化反応によるロス分も考慮した精錬が
可能である。[0013] From the above, according to the present invention method, after the atmospheric pressure refining with the same refining vessel, CO in refining method in which the vacuum refining, the progress of the oxidation reaction with a conventional decomposition reaction during the reduction process has been feared 2 Can be used, and efficient refining can be performed. Further, in vacuum refining, there are steel types that do not require decarburization refining depending on the type of steel, but in this case, efficient refining can be performed by performing only reduction refining under vacuum. In addition, CO
2 When the flow rate is close to 0.2 Nm 3 / min per molten steel and the degree of vacuum is close to 100 Torr, some CO 2
The decomposition reaction of 1 proceeds and the oxidation by decomposed O 2 proceeds, but there is no problem because the reaction rate is small as shown in FIGS. 2 and 3. Further, since the CO 2 reaction rate is also quantified, it is possible to perform refining in consideration of the loss amount due to the oxidation reaction.
【００１４】[0014]
【作用】ＣＯ2 は鋼浴中に吹込んだ場合、一部に式で
示されるように分解せずにそのまま浮上するとの定性的
な知見が示されているが、一般には前記式で示される
ようにＣＯと１／２Ｏ2 に分解し、さらに酸化が進みや
すい条件下では前記式の反応まで進行すると考えられ
てきた。When CO 2 is blown into the steel bath, it is qualitatively known that CO 2 floats as it is without being decomposed as shown in the equation, but it is generally shown by the above equation. It has been considered that the reaction proceeds to the reaction of the above formula under the condition that it is decomposed into CO and 1 / 2O 2 and the oxidation is more likely to proceed.
【００１５】 ＣＯ2 （ｇ）＝ＣＯ2 （ｇ） ………………………… 含クロム溶鋼では脱炭の進行により〔Ｃ〕濃度が低下し
た状態になると、式で示される溶鋼中に多量に含まれ
る〔Ｃｒ〕の酸化反応が進行する。 ２〔Ｃｒ〕＋３／２Ｏ2 （ｇ）＝（Ｃｒ2 Ｏ3 ） …… 本発明者らは、前記式および式で示されるＣＯ2 の
分解反応が式の反応の進行しやすさで左右されること
を見出した。つまり、式の反応がしにくい条件である
真空精錬条件下および溶鋼攪拌力の大きい高吹込みガス
流量の条件下であれば、ＣＯ2 の反応率を低位にするこ
とが可能である。また、前記式および式に関与しな
かった未分解のＣＯ2 はＡｒガスやＮ2 ガス等の不活性
ガスと同等の作用をもつことを見出した。CO 2 (g) = CO 2 (g) In the molten steel containing chromium, when the [C] concentration decreases due to the progress of decarburization, the molten steel represented by the formula The oxidation reaction of [Cr] contained in a large amount progresses. 2 [Cr] + 3 / 2O 2 (g) = (Cr 2 O 3 ) ... The inventors of the present invention depend on the ease with which the decomposition reaction of CO 2 represented by the above formula and the formula is advanced. I found that. That is, the reaction rate of CO 2 can be lowered under the conditions of vacuum refining, which is a condition in which the reaction of the formula is difficult, and under the condition of a high blowing gas flow rate with a large molten steel stirring force. It was also found that the above formula and undecomposed CO 2 that did not participate in the formula had the same action as an inert gas such as Ar gas or N 2 gas.
【００１６】含クロム溶鋼の還元処理では脱炭処理時に
酸化した〔Ｃｒ〕を還元剤を添加して還元処理するとと
もに、溶鋼中の成分を目標濃度に調整することも行う。
このため、Ｎ2 ガスを使用した場合には溶鋼中〔Ｎ〕濃
度の急激な増大が起きるために使用するガスとしては特
殊な場合を除きＡｒガスを使用する。Ａｒガスは他のガ
スに比べて高価であることから不利である。ＣＯ2 はＡ
ｒガスに比べて安価であり、本発明者らが見出した条件
であれば、反応率も低く、効率的な精錬が可能になる。In the reduction treatment of the chromium-containing molten steel, the [Cr] oxidized during the decarburization treatment is reduced by adding a reducing agent, and the components in the molten steel are adjusted to the target concentrations.
Therefore, when N 2 gas is used, Ar gas is used as a gas to be used because a sudden increase in the [N] concentration in the molten steel occurs except in special cases. Ar gas is disadvantageous because it is more expensive than other gases. CO 2 is A
It is cheaper than r gas, and under the conditions found by the present inventors, the reaction rate is low and efficient refining becomes possible.
【００１７】[0017]
【実施例】ＳＵＳ３０４ステンレス鋼（８ｍａｓｓ％Ｎ
ｉ−１８ｍａｓｓ％Ｃｒ）で目標の〔Ｃ〕濃度が０．０
５〜０．０７ｍａｓｓ％、〔Ｎ〕濃度が０．０３〜０．
０５ｍａｓｓ％の範囲を要求される鋼６０ｔｏｎの処理
を図１に示す実施態様で実施した。脱炭開始時の〔Ｃ〕
濃度は全て１．５ｍａｓｓ％とし、真空精錬を開始する
までは酸素または酸素と不活性ガスの混合ガスを用いて
精錬を行い、真空精錬では不活性ガスのみを用いて精錬
を行った。なお、目標〔Ｃ〕濃度までの脱炭処理を大気
圧下で行った場合と真空精錬で行った場合の両方で実施
した。還元処理は還元剤にＦｅ−Ｓｉを用い、脱炭処理
で酸化した〔Ｃｒ〕を回収するために必要な還元剤の量
およびＣＯ2 の分解で酸化する量を求め、この量に製品
に要求される〔Ｓｉ〕濃度分も含めてＦｅ−Ｓｉの添加
を行い、真空下でのＣＯ2 の吹込みを行った。なお、還
元処理はいずれも５ｍｉｎ間の処理を行った。その後、
大気圧状態に戻し、取鍋に出鋼した。[Example] SUS304 stainless steel (8 mass% N
i-18 mass% Cr), the target [C] concentration is 0.0
5 to 0.07 mass%, [N] concentration is 0.03 to 0.
The treatment of 60 tonnes of steel requiring a range of 05 mass% was carried out in the embodiment shown in FIG. [C] at the start of decarburization
All the concentrations were 1.5 mass%, and refining was performed using oxygen or a mixed gas of oxygen and an inert gas until the vacuum refining was started, and in the vacuum refining, refining was performed using only an inert gas. The decarburization treatment up to the target [C] concentration was carried out both under atmospheric pressure and under vacuum refining. In the reduction treatment, Fe-Si was used as a reducing agent, and the amount of the reducing agent necessary for recovering [Cr] oxidized by the decarburization treatment and the amount oxidized by the decomposition of CO 2 were obtained, and the amount required for the product Fe—Si was added including the [Si] concentration, and CO 2 was blown in under vacuum. The reduction treatment was performed for 5 minutes. afterwards,
It returned to atmospheric pressure and tapped in a ladle.
【００１８】表１に脱炭処理時の真空度および還元処理
時の精錬条件の実施例を示す。本発明の実施例は先に示
した条件を満足するようにして実施した。比較例のＮ
ｏ．６は還元処理を大気圧下で実施した例、比較例のＮ
ｏ．７、Ｎｏ．８は従来例である特開平４−２１４８６
号公報および特開平４−２６３００５号公報記載の方法
に準じて実施した例、比較例のＮｏ．９は処理時の真空
度が本発明の条件外の例、比較例のＮｏ．１０はガス吹
込み流量が本発明の条件外の例である。Table 1 shows examples of vacuum degree during decarburization and refining conditions during reduction. The examples of the present invention were carried out so as to satisfy the above-mentioned conditions. Comparative example N
o. No. 6 is an example in which the reduction treatment is carried out under atmospheric pressure, N in the comparative example.
o. 7, No. No. 8 is a conventional example.
Nos. Of Comparative Examples and Examples carried out according to the methods described in Japanese Patent Laid-Open No. Hei 4-263005. No. 9 of the comparative example is a case where the degree of vacuum during processing is outside the conditions of the present invention. No. 10 is an example in which the gas injection flow rate is outside the conditions of the present invention.
【００１９】実施結果を表２に示す。表中の値は本発明
例のＮｏ．１の結果を１００として比例換算した値であ
る。本発明例では還元剤原単位およびＡｒガス原単位と
もに低位に安定しており、その結果、精錬コストも低位
に安定している。一方、比較例では一部に還元剤原単位
が本発明例より良好な場合もあるが、Ａｒガス原単位は
高位となっており、その結果、精錬コストも高位になっ
ている。The execution results are shown in Table 2. The values in the table are the numbers of the invention examples. It is a value obtained by proportionally converting the result of 1 as 100. In the present invention example, both the reducing agent basic unit and the Ar gas basic unit are stable at a low level, and as a result, the refining cost is also stable at a low level. On the other hand, in some comparative examples, the reducing agent basic unit may be better than that of the present invention in some cases, but the Ar gas basic unit is high, and as a result, the refining cost is also high.
【００２０】[0020]
【表１】 [Table 1]
【００２１】[0021]
【表２】 [Table 2]
【００２２】[0022]
【発明の効果】本発明法によると、含クロム溶鋼の同一
精錬容器を用いた大気圧精錬後の真空精錬において、還
元処理をＣＯ2 を用いることにより精錬コストの低減が
達成できる。さらに、還元処理でＮ2 ガスを用いた場合
に問題となる〔Ｎ〕濃度の増大を防止できることから、
目標〔Ｎ〕濃度に合わせた〔Ｎ〕濃度制御が容易にな
り、精錬コストの大幅な低減が可能になる。According to the method of the present invention, in the vacuum refining after the atmospheric refining using the same refining vessel for molten chromium-containing steel, the refining cost can be reduced by using CO 2 for the reduction treatment. Furthermore, since it is possible to prevent an increase in [N] concentration, which is a problem when N 2 gas is used in the reduction treatment,
It becomes easy to control the [N] concentration according to the target [N] concentration, and the refining cost can be significantly reduced.
【図面の簡単な説明】[Brief description of drawings]
【図１】本発明の実施態様例の精錬容器を示す図であ
る。FIG. 1 is a diagram showing a refining vessel according to an embodiment of the present invention.
【図２】本発明法における還元処理時のＣＯ2 の吹込み
流量の下限の限定理由を示す図である。FIG. 2 is a diagram showing the reason for limiting the lower limit of the flow rate of CO 2 blown during the reduction treatment in the method of the present invention.
【図３】本発明法における還元処理でのＣＯ2 吹込み時
の真空度の上限の限定理由を示す図である。FIG. 3 is a diagram showing the reason for limiting the upper limit of the degree of vacuum when blowing CO 2 in the reduction treatment in the method of the present invention.
１ 精錬容器 ２ 底吹き羽口 ３ 排気フード ４ 溶鋼 ５ ガス 1 Refining container 2 Bottom blowing tuyere 3 Exhaust hood 4 Molten steel 5 Gas
───────────────────────────────────────────────────── フロントページの続き (72)発明者 森重 博明 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Morishige 3434 Shimada, Hikari City, Yamaguchi Prefecture Nippon Steel Co., Ltd.
Claims (2)
炭処理後、真空下での脱炭および還元処理を行う含クロ
ム溶鋼の精錬法において、前記還元処理を溶鋼トン当り
０．２Ｎｍ3 ／ｍｉｎ以上の二酸化炭素ガスを吹込みな
がら真空度１００Ｔｏｒｒ以下の真空下で行うことを特
徴とする含クロム溶鋼の精錬法。1. A refining method for chromium-containing molten steel, which comprises decarburizing treatment under atmospheric pressure using the same refining vessel, and then performing decarburizing and reducing treatment under vacuum, wherein the reduction treatment is carried out at a rate of 0. A refining method for molten chromium-containing steel, which is carried out under a vacuum with a vacuum degree of 100 Torr or less while blowing carbon dioxide gas of 2 Nm 3 / min or more.
炭処理後、還元処理のみを真空下で行うことを特徴とす
る請求項１記載の含クロム溶鋼の精錬法。2. The method for refining molten chromium-containing steel according to claim 1, wherein after the decarburization treatment under atmospheric pressure using the same refining vessel, only the reduction treatment is performed under vacuum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22538194A JPH0885811A (en) | 1994-09-20 | 1994-09-20 | Method for refining molten chromium-containing steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22538194A JPH0885811A (en) | 1994-09-20 | 1994-09-20 | Method for refining molten chromium-containing steel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0885811A true JPH0885811A (en) | 1996-04-02 |
Family
ID=16828470
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22538194A Withdrawn JPH0885811A (en) | 1994-09-20 | 1994-09-20 | Method for refining molten chromium-containing steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0885811A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003096515A (en) * | 2001-09-20 | 2003-04-03 | Nippon Steel Corp | Method for refining molten extra-low carbon chromium- containing steel |
| JP2003096514A (en) * | 2001-09-20 | 2003-04-03 | Nippon Steel Corp | Method for refining molten chromium-containing steel |
-
1994
- 1994-09-20 JP JP22538194A patent/JPH0885811A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003096515A (en) * | 2001-09-20 | 2003-04-03 | Nippon Steel Corp | Method for refining molten extra-low carbon chromium- containing steel |
| JP2003096514A (en) * | 2001-09-20 | 2003-04-03 | Nippon Steel Corp | Method for refining molten chromium-containing steel |
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