JPH06145762A - Method for decarburize-refining molten chromium-containing steel - Google Patents
Method for decarburize-refining molten chromium-containing steelInfo
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- JPH06145762A JPH06145762A JP29608692A JP29608692A JPH06145762A JP H06145762 A JPH06145762 A JP H06145762A JP 29608692 A JP29608692 A JP 29608692A JP 29608692 A JP29608692 A JP 29608692A JP H06145762 A JPH06145762 A JP H06145762A
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- Prior art keywords
- oxygen
- molten steel
- tuyere
- gas
- refining
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は上底吹き転炉、アルゴン
−酸素脱炭炉（ＡＯＤ炉）等の底吹き可能な転炉を用い
てステンレス鋼等のクロム含有溶鋼を脱炭精錬する方法
に関する。FIELD OF THE INVENTION The present invention relates to a method for decarburizing and refining molten chromium-containing steel such as stainless steel using a bottom-blown converter such as a top-blown converter and an argon-oxygen decarburizing furnace (AOD furnace). Regarding
【０００２】[0002]
【従来の技術】クロムを含有する溶鋼、代表的にはステ
ンレス鋼は、一般に低炭素であることを必要としている
が、クロムが脱炭反応の進行を妨げるため、炭素鋼に比
べて脱炭精錬が難しいことはよく知られている。2. Description of the Related Art Molten steel containing chromium, typically stainless steel, generally requires a low carbon content, but since chromium interferes with the progress of the decarburization reaction, decarburization and refining compared to carbon steel. It is well known that it is difficult.
【０００３】ステンレス鋼の脱炭精錬は、炭素鋼と同
様、一般に酸素製鋼法により行われるが、酸素との反応
性に富むクロムの酸化ロスを低減するため、脱炭生成物
であるＣＯの分圧を下げて脱炭反応を促進させ、短時間
で効率的に精錬を終了する必要がある。Similar to carbon steel, decarburization refining of stainless steel is generally carried out by an oxygen steelmaking method. However, in order to reduce the oxidation loss of chromium, which is highly reactive with oxygen, the content of CO, which is a decarburization product, is reduced. It is necessary to lower the pressure to accelerate the decarburization reaction and efficiently finish the refining in a short time.
【０００４】この目的で開発されたのが、真空脱炭法と
アルゴン−酸素脱炭法（ＡＯＤ法）であり、いずれもＣ
Ｏ分圧を低下させて、効率的にステンレス鋼を脱炭精錬
することができる。このうち、高炭素域からの適用が可
能で、かつ転炉のみで精錬を実施できるＡＯＤ法がより
簡便な方法であることから、ステンレス鋼の脱炭精錬に
広く利用されるようになってきた。ＡＯＤ法では、底吹
き転炉または上底吹き転炉を使用し、脱炭に必要な酸素
以外にＣＯの希釈ガスとして不活性ガスを溶鋼に吹込
み、ＣＯ分圧を低下させつつ精錬を行う。The vacuum decarburization method and the argon-oxygen decarburization method (AOD method) were developed for this purpose.
The O partial pressure can be reduced to efficiently decarburize and refine stainless steel. Of these, the AOD method, which can be applied from the high carbon region and can be refined only by a converter, is more widely used for decarburizing and refining stainless steel. . In the AOD method, a bottom-blown converter or a top-blown converter is used, and in addition to oxygen necessary for decarburization, an inert gas is blown into the molten steel as a CO dilution gas to perform refining while reducing the CO partial pressure. .
【０００５】脱炭時にクロムが酸化される程度は溶鋼中
Ｃ濃度が低くなる程顕著になるため、ＡＯＤ法ではＣ濃
度の低下につれて不活性ガスの割合を上げていくのが普
通である。しかし、精錬初期のＣ濃度が高く、比較的ク
ロムが酸化しにくい領域においても、ある程度の濃度の
不活性ガスを酸素と共に不可避的に流している。Since the degree of oxidation of chromium during decarburization becomes more remarkable as the C concentration in molten steel becomes lower, it is common in the AOD method to increase the proportion of the inert gas as the C concentration decreases. However, even in a region where the C concentration is high at the initial stage of refining and chromium is relatively hard to be oxidized, an inert gas having a certain concentration is inevitably flown together with oxygen.
【０００６】[0006]
【発明が解決しようとする課題】前述のように、従来の
ＡＯＤ法においては、精錬全期にわたって酸素と共に不
活性ガスを大量に (例えば、酸素の吹込み量とほぼ同
量) 使用する必要がある。不活性ガスとして安価な窒素
ガスを用いればコストは安くなるが、鋼中Ｎ濃度が上昇
するという問題がある。As described above, in the conventional AOD method, it is necessary to use a large amount of inert gas together with oxygen (for example, almost the same amount as the blowing amount of oxygen) in the entire refining period. is there. If cheap nitrogen gas is used as the inert gas, the cost will be reduced, but there is a problem that the N concentration in the steel increases.
【０００７】そのため「アルゴン−酸素脱炭法」の名が
示しているように、ＡＯＤ法によるステンレス鋼の脱炭
精錬においては、高価なアルゴンを大量に使用する必要
があり、ステンレス鋼のコストを増大させていた。本発
明の目的は、アルゴンの使用量の大幅な低減が可能な、
或いはアルゴンの使用が不必要な、ステンレス鋼などの
クロム含有鋼の効率的な脱炭精錬方法を提供することで
ある。Therefore, as the name of "argon-oxygen decarburization method" indicates, in the decarburization and refining of stainless steel by the AOD method, it is necessary to use a large amount of expensive argon, which reduces the cost of stainless steel. Was increasing. The object of the present invention is to significantly reduce the amount of argon used,
Another object is to provide an efficient decarburization refining method for chromium-containing steel such as stainless steel, which does not require the use of argon.
【０００８】[0008]
【課題を解決するための手段】本発明者は、上記目的を
達成するため、アルゴンに代えて比較的安価な炭化水素
ガスをＣＯ希釈ガスとして使用することに着目した。炭
化水素ガス (ＣmＨn ) を溶鋼中に吹き込めば、 ＣmＨn ＝ mＣ ＋ n/2 Ｈ2 ・・・ (1) の反応によりＨ2 が発生し、このＨ2 がＣＯ希釈ガスと
して作用する。しかも、上記反応式に示されるように、
ＣmＨn は分解すると数倍の体積に膨張するため、比較
的少量の炭化水素ガスで大きな攪拌力とＣＯ希釈効果が
得られ、脱炭が促進される結果、ステンレス鋼の脱炭精
錬におけるクロムの酸化ロスの低減に大きな効果がある
ことが判明した。In order to achieve the above object, the present inventor has noticed that a relatively inexpensive hydrocarbon gas is used as a CO diluting gas instead of argon. If hydrocarbon gas (C m H n ) is blown into the molten steel, H 2 is generated by the reaction of C m H n = mC + n / 2 H 2 (1), and this H 2 is a CO dilution gas. Acts as. Moreover, as shown in the above reaction formula,
Since C m H n expands to several times its volume when decomposed, a large stirring force and CO dilution effect are obtained with a relatively small amount of hydrocarbon gas, and decarburization is promoted, resulting in decarburization and refining of stainless steel. It was found that it has a great effect in reducing the oxidation loss of chromium.
【０００９】炭化水素ガスを大量に吹込むと、羽口先端
が過冷却になって詰まり易いため、安定な操業が困難で
あるが、先に本発明者が提案した三重管構造の羽口を用
い、炭化水素ガスを最も外側と中心の二つの流路より、
酸素を中間の流路より吹込むことにより、大量の炭化水
素ガスを吹込んでも、羽口の詰まりを引き起こさずに安
定してステンレス鋼の脱炭精錬を続けることができるこ
とも判明した。When a large amount of hydrocarbon gas is blown into the tuyere, the tip of the tuyere becomes overcooled and is easily clogged, which makes stable operation difficult. However, the tuyere of the triple pipe structure previously proposed by the present inventor is used. Using the hydrocarbon gas from the two outermost and central channels,
It was also found that by blowing oxygen from an intermediate passage, even if a large amount of hydrocarbon gas was blown, decarburization and refining of stainless steel could be continued stably without causing clogging of tuyere.
【００１０】ここに、本発明の要旨とするところは、上
吹きランスより酸素を吹込み、または吹込まずに、溶鋼
浴面下において羽口より炭化水素ガスを酸素および／ま
たは不活性ガスと同時に溶鋼中に吹込むことを特徴とす
る、クロム含有溶鋼の脱炭精錬方法にある。Here, the gist of the present invention is to blow oxygen from the top blowing lance or to blow hydrocarbon gas from the tuyere under the surface of the molten steel at the same time as oxygen and / or an inert gas without blowing. It is a method for decarburizing and refining molten steel containing chromium, which is characterized by blowing into molten steel.
【００１１】本発明の好適態様にあっては、溶鋼浴面下
に浸漬した羽口が、同心円状の三重管構造を有してお
り、最も外側の流路より炭化水素ガスを、その内側の流
路より酸素を、中心の流路より炭化水素ガスを吹き込
む。In a preferred embodiment of the present invention, the tuyere submerged below the surface of the molten steel has a concentric triple tube structure, and hydrocarbon gas is introduced from the outermost flow passage, Oxygen is blown in from the flow channel, and hydrocarbon gas is blown in from the central flow channel.
【００１２】また、上記の脱炭精錬方法を、溶鋼の炭素
濃度が0.05〜0.20重量％の範囲内に低下するまで行い、
その後、羽口よりの吹込みガスを酸素と不活性ガスとに
切り換えて精錬を続けることにより、脱炭率をより向上
させることができる。Further, the above decarburization refining method is carried out until the carbon concentration of the molten steel falls within the range of 0.05 to 0.20% by weight,
Then, the decarburization rate can be further improved by switching the gas blown from the tuyere to oxygen and an inert gas and continuing refining.
【００１３】[0013]
【作用】溶鋼への羽口からの炭化水素ガスの吹込みは、
炭素鋼の精錬においては、酸素底吹き時の羽口ノズル溶
損を防止するために、羽口付近の溶鋼を冷却する目的で
従来より行われてきた。これは、上記(1) 式の反応が吸
熱反応であることを利用したものであり、炭化水素ガス
の吹込み量は冷却に必要な比較的少量 (例、酸素流量の
15％以下) であった。ＣＯ希釈に必要な多量の炭化水素
ガスの吹込みは、過冷却による羽口詰まりの原因となる
ので、避けるのが常識であった。[Operation] The injection of hydrocarbon gas from the tuyere into the molten steel
In the refining of carbon steel, in order to prevent the melting of the tuyere nozzle at the time of oxygen bottom blowing, it has been conventionally performed for the purpose of cooling the molten steel near the tuyere. This utilizes the fact that the reaction of the above equation (1) is an endothermic reaction, and the injection amount of hydrocarbon gas is relatively small (for example, the oxygen flow rate
15% or less). Blowing in a large amount of hydrocarbon gas necessary for CO dilution causes clogging of tuyere due to supercooling, and it is common sense to avoid it.
【００１４】これに対し、本発明では、ステンレス鋼の
脱炭精錬において、炭化水素ガスをＣＯ分圧低下のため
のＣＯ希釈ガスとして使用する。即ち、炭化水素ガスの
分解により発生するＨ2 が脱炭の促進と、酸素との親和
力の強いクロムの酸化ロス低減に効果的であることを利
用したものであって、炭素鋼の精錬とは、炭化水素ガス
の吹込みの目的が全く異なる。この目的には、炭素鋼の
精錬における場合に比べて、非常に多量の炭化水素ガス
の吹込みが必要となる。多量の炭化水素ガスの羽口から
の吹込みは過冷却を伴い易く、安定な精錬が困難となる
ことから、これまでステンレス鋼の脱炭精錬に炭化水素
ガスが使用されてこなかったと考えられる。On the other hand, in the present invention, in decarburizing and refining stainless steel, hydrocarbon gas is used as a CO diluting gas for reducing the CO partial pressure. That is, the fact that H 2 generated by the decomposition of hydrocarbon gas is effective in promoting decarburization and reducing the oxidation loss of chromium, which has a strong affinity with oxygen, is used to refine carbon steel. , The purpose of blowing hydrocarbon gas is completely different. For this purpose, it is necessary to inject a very large amount of hydrocarbon gas as compared with the case of refining carbon steel. It is considered that hydrocarbon gas has not been used for decarburization and refining of stainless steel because it is easy to blow a large amount of hydrocarbon gas from the tuyere with supercooling and stable refining becomes difficult.
【００１５】このように、本発明において溶鋼に浸漬し
た羽口より炭化水素ガスを吹き込む理由は、炭化水素が
分解して発生したＨ2 が、脱炭生成物として生成するＣ
Ｏを希釈し、脱炭反応を促進させ、しかもクロム酸化ロ
スを低減させるという効果があるからである。同時に、
(1) 式に示すように、炭化水素の分解によりガス体積が
数倍に増大することから、炭化水素ガスの吹込みによ
り、従来のアルゴン (または他の不活性ガス) の吹込み
より少ない流量のガスで溶鋼の強攪拌を行うことができ
る。従って、ＣＯ希釈ガスとして炭化水素ガスを使用し
ても、アルゴンを使用した場合と同様に、クロムの酸化
を防止しつつ、脱炭を行うことが可能となる。炭化水素
ガスはアルゴンに比べて相当に安価であることから、炭
化水素ガスの使用によりステンレス鋼の精錬コストが低
減する。As described above, in the present invention, the reason why the hydrocarbon gas is blown from the tuyere immersed in the molten steel is that H 2 generated by the decomposition of the hydrocarbon is generated as a decarburized product.
This is because it has the effect of diluting O, promoting the decarburization reaction, and reducing the chromium oxidation loss. at the same time,
As shown in Eq. (1), the gas volume increases several times due to the decomposition of hydrocarbons, so the flow rate of hydrocarbon gas is smaller than that of conventional argon (or other inert gas) injection. The molten steel can be vigorously stirred with the above gas. Therefore, even if the hydrocarbon gas is used as the CO dilution gas, it is possible to decarburize while preventing the oxidation of chromium, as in the case of using argon. Since hydrocarbon gas is significantly cheaper than argon, the use of hydrocarbon gas reduces the refining cost of stainless steel.
【００１６】本発明のクロム含有溶鋼の脱炭精錬方法
は、上底吹き転炉あるいは底吹き転炉(例、ＡＯＤ炉)
で実施することができる。底吹き転炉の場合には、溶鋼
浴面下において羽口より炭化水素ガスを酸素と同時に溶
鋼中に吹込むことにより精錬を行う。上底吹き転炉の場
合には、上吹きランスより酸素を吹込み、溶鋼浴面下に
おいて羽口より炭化水素ガスを酸素または不活性ガスと
同時に溶鋼中に吹込む。上吹きランスより吹込まれる酸
素、或いは羽口より溶鋼に吹込まれる酸素と炭化水素ガ
スには、いずれも不活性ガス (例、アルゴン) を混入し
てもよい。The method for decarburizing and refining molten steel containing chromium of the present invention is a bottom-blown converter or bottom-blown converter (eg, AOD furnace).
Can be implemented in. In the case of a bottom-blowing converter, refining is performed by blowing a hydrocarbon gas into the molten steel from the tuyere simultaneously with oxygen under the surface of the molten steel bath. In the case of the top-bottom blow converter, oxygen is blown from the top-blowing lance, and hydrocarbon gas is blown into the molten steel from the tuyere below the molten steel bath surface at the same time as oxygen or an inert gas. An inert gas (eg, argon) may be mixed in the oxygen blown from the top blowing lance or the oxygen and the hydrocarbon gas blown into the molten steel from the tuyere.
【００１７】炭化水素ガスの吹込み量は特に制限されな
いが、羽口から吹込まれる酸素流量に対して10〜150 ％
とすることが好ましい。酸素および炭化水素ガスの少な
くとも一方に不活性ガスを混入する場合には、不活性ガ
スが炭化水素ガスと同様にＣＯ希釈ガスとして作用する
ので、炭化水素ガスの吹込み量をその分だけ少なくする
ことができる。逆に言うと、炭化水素ガスを不活性ガス
であるアルゴンと併用することで、高価なアルゴンの吹
込み量を大幅に低減することができる。羽口から炭化水
素ガスと不活性ガスのみを吹込む場合には、炭化水素ガ
スの吹込み量は、不活性ガスの流量に対して10〜50％と
することが好ましい。The amount of hydrocarbon gas blown is not particularly limited, but is 10 to 150% with respect to the flow rate of oxygen blown from the tuyere.
It is preferable that When an inert gas is mixed in at least one of oxygen and hydrocarbon gas, the inert gas acts as a CO diluting gas like the hydrocarbon gas, so the amount of the hydrocarbon gas blown is reduced by that amount. be able to. Conversely, by using a hydrocarbon gas in combination with argon, which is an inert gas, the amount of expensive argon blown in can be greatly reduced. When only the hydrocarbon gas and the inert gas are blown from the tuyere, the blowing amount of the hydrocarbon gas is preferably 10 to 50% with respect to the flow rate of the inert gas.
【００１８】溶鋼浴面下での羽口からの酸素と炭化水素
ガスの吹込みは、同心円状の二重管構造の羽口を用い
て、通常は中心流路から酸素を、外側の流路から炭化水
素ガスを吹込むことにより行うこともできるが、多量の
炭化水素ガスを吹込むと、炭化水素ガスの吹込みに伴う
冷却によるノズル詰まりが起こり易く、操業が不安定に
なるという欠点がある。しかし、例えば、酸素と炭化水
素ガスの一方または両方に不活性ガスを混入することで
炭化水素ガスの吹込み量が比較的少なくてよい場合に
は、過冷却は起こりにくいので、二重管構造の羽口を用
いても安定して精錬を行うことができる。また、炭化水
素ガスと不活性ガスのみを羽口から吹込む場合には、一
重管 (単管) を使用することもできる。For the injection of oxygen and hydrocarbon gas from the tuyere below the surface of the molten steel, the concentric double-tube tuyere is usually used to supply oxygen from the central flow passage and the outer flow passage. It is also possible to inject the hydrocarbon gas from the above, but when injecting a large amount of the hydrocarbon gas, the nozzle clogging due to the cooling due to the injection of the hydrocarbon gas is likely to occur and the operation becomes unstable. is there. However, for example, when an inert gas is mixed in one or both of oxygen and hydrocarbon gas so that a relatively small amount of hydrocarbon gas can be blown in, supercooling is less likely to occur. It is possible to carry out stable refining even with the tuyere. Further, when only the hydrocarbon gas and the inert gas are blown from the tuyere, a single pipe (single pipe) can be used.
【００１９】不活性ガスを混入せず、炭化水素ガスと酸
素とを溶鋼浴面下に吹込む場合のように、炭化水素ガス
の吹込量が比較的多い時には、本発明者が特願平４−17
898号において提案した、図１に示すような同心円状の
三重管構造の羽口を用い、最も外側の流路１より炭化水
素ガスを、その内側の流路２より酸素を、中心の流路３
より炭化水素ガスを吹き込むことが好ましい。それによ
り、羽口先端の過冷却によるノズル閉塞を引き起こさず
に、上述した酸素流量の10〜150 ％という多量の炭化水
素ガスを安定して羽口から吹込むことができる。流路１
と流路３における炭化水素ガス流量の配分は、流路３の
炭化水素ガス流量を流路１の流量の0.5〜３倍とするこ
とが好ましい。もちろん、三重管構造の羽口を使用する
場合でも、各流路に流す酸素および炭化水素ガスに不活
性ガスを混入しても差し支えない。When the amount of the hydrocarbon gas blown is relatively large, as in the case where the hydrocarbon gas and oxygen are blown below the surface of the molten steel bath without mixing the inert gas, the present inventor proposes Japanese Patent Application No. -17
Using the tuyere of the concentric triple tube structure as shown in FIG. 1 proposed in No. 898, hydrocarbon gas is supplied from the outermost flow path 1, oxygen is supplied from the inner flow path 2, and central flow path is provided. Three
It is more preferable to blow in a hydrocarbon gas. As a result, a large amount of the hydrocarbon gas of 10 to 150% of the above oxygen flow rate can be stably blown from the tuyere without causing the nozzle clogging due to the supercooling of the tip of the tuyere. Channel 1
The distribution of the flow rate of the hydrocarbon gas in the channel 3 is preferably such that the flow rate of the hydrocarbon gas in the channel 3 is 0.5 to 3 times the flow rate of the channel 1. Of course, even when the tuyere having a triple tube structure is used, it is possible to mix an inert gas with the oxygen and hydrocarbon gases flowing through each flow path.
【００２０】本発明で使用する炭化水素は、プロパンが
最も一般的であるが、メタン、エタン、ブタン等の他の
炭化水素でも原理的には全く問題ない。また２種以上の
炭化水素の混合ガスあるいは液化天然ガス、液化石油ガ
ス等を使用することも可能である。Propane is most commonly used as the hydrocarbon used in the present invention, but other hydrocarbons such as methane, ethane and butane can be used in principle without any problem. It is also possible to use a mixed gas of two or more kinds of hydrocarbons, liquefied natural gas, liquefied petroleum gas, or the like.
【００２１】本発明の脱炭精錬方法は、特に溶鋼中Ｃ濃
度が比較的高い脱炭初期において脱炭促進に非常に有効
であり、従来のアルゴンを用いたＡＯＤ法より、安価で
あるにもかかわらず、好成績をあげることができる。し
かし、溶鋼中Ｃ濃度が低下する脱炭末期になると、相対
的にクロムが酸化され易くなる上、炭化水素が分解して
生じたＣが燃焼して、ＣＯガス希釈効果が小さくなり、
脱炭が進行しにくくなる。このため、Ｃ濃度が低下する
精錬末期では、羽口からのガスを酸素と不活性ガスとの
吹込みに切り換えた方が、クロムの酸化ロス防止および
脱炭率向上に有利な場合もある。The decarburization refining method of the present invention is very effective for promoting decarburization, especially at the initial stage of decarburization where the C concentration in the molten steel is relatively high, and is cheaper than the conventional AOD method using argon. Nevertheless, you can get good results. However, in the final stage of decarburization where the C concentration in molten steel decreases, chromium is relatively easily oxidized and C generated by decomposition of hydrocarbons is burned to reduce the CO gas dilution effect.
Decarburization becomes difficult to proceed. Therefore, in the final stage of refining where the C concentration decreases, switching the gas from the tuyere to blowing of oxygen and an inert gas may be advantageous in preventing oxidation loss of chromium and improving the decarburization rate.
【００２２】即ち、溶鋼中Ｃ濃度が0.05〜0.20重量％の
範囲内に低下するまでは、上で説明したように、羽口か
ら溶鋼浴面下に炭化水素ガスと酸素および／または不活
性ガスとを吹込み、次いで羽口よりの吹込みガスを酸素
と不活性ガスとに切り換えて精錬を行う方法である。そ
れにより、クロムの酸化ロスの低減と脱炭率の向上を図
ることができる。That is, until the C concentration in the molten steel falls within the range of 0.05 to 0.20% by weight, as described above, hydrocarbon gas and oxygen and / or an inert gas are introduced from the tuyere to below the molten steel bath surface. And then the gas blown from the tuyere is switched between oxygen and inert gas for refining. As a result, it is possible to reduce the oxidation loss of chromium and improve the decarburization rate.
【００２３】切替え時の溶鋼中Ｃ濃度の下限を0.05重量
％としたのは、それ以下の低炭素領域まで炭化水素を使
用すると、クロムの酸化ロスが多くなり、コスト的に不
利になると共に、溶鋼中Ｃ濃度0.05重量％以下といった
低炭素までの脱炭が困難であるからである。一方、切替
え時の溶鋼中Ｃ濃度の上限を0.20重量％としたのは、そ
れ以上の高炭素領域では、炭化水素を吹込んでも十分に
脱炭が可能であり、高価なアルゴンを吹込んだのと同等
またはそれ以上の精錬効果が得られるからである。The lower limit of the C concentration in the molten steel at the time of switching is set to 0.05% by weight. When hydrocarbons are used up to a low carbon region below that, oxidation loss of chromium increases, which is disadvantageous in cost. This is because it is difficult to decarburize carbon to a low carbon content of 0.05% by weight or less in molten steel. On the other hand, the upper limit of the C concentration in the molten steel at the time of switching was set to 0.20% by weight, because in the high carbon region higher than that, sufficient decarburization is possible even by blowing hydrocarbons, and expensive argon was blown. This is because a refining effect equal to or higher than that of can be obtained.
【００２４】或いは、上記のように炭化水素ガスを羽口
から吹込んで溶鋼中Ｃ濃度が0.05〜0.20重量％の領域ま
で脱炭した溶鋼を、真空脱炭などの別の脱炭精錬により
さらに精錬することも可能である。Alternatively, as described above, the hydrocarbon steel is blown from the tuyere to decarburize it until the C concentration in the molten steel is in the range of 0.05 to 0.20% by weight, and the molten steel is further refined by another decarburization refining such as vacuum decarburization. It is also possible to do so.
【００２５】本発明の脱炭精錬方法は、オーステナイト
系およびフェライト系のステンレス鋼のほか、Cr濃度が
10％以下のクロム含有鋼にも適用できる。次に、実施例
により本発明の効果を例証する。実施例中、％は特に指
定しない限り、重量％である。The decarburizing and refining method of the present invention is applicable to austenitic and ferritic stainless steels as well as Cr
It can also be applied to steel containing less than 10% chromium. Next, the effects of the present invention will be illustrated by examples. In the examples,% is% by weight unless otherwise specified.
【００２６】[0026]
【実施例】実施例１ Ｃ濃度0.40％、Cr濃度18.0％、温度1600℃の溶鋼10トン
対し、上吹きランスより酸素を260 Nm3/hr、同心円状三
重管構造の羽口の最も外側の流路よりプロパンを60 Nm3
/hr 、その内側の流路より酸素を220 Nm3/hr、中心の流
路よりプロパンを100 Nm3/hr吹込んで脱炭を行った。脱
炭開始20分後の溶鋼中Ｃ濃度は0.13％、Cr濃度は16.5％
であり、開始40分後の溶鋼中Ｃ濃度は0.08％、Cr濃度は
15.2％であった。40分間の脱炭精錬中に、羽口先端での
過冷却によるノズル詰まりは全く起こらず、精錬は安定
して円滑に進行した。[Examples] Example 1 With respect to 10 tons of molten steel having a C concentration of 0.40%, a Cr concentration of 18.0% and a temperature of 1600 ° C, oxygen was supplied from a top blowing lance to 260 Nm 3 / hr, and the outermost tuyere of a concentric triple pipe structure was used. 60 Nm 3 of propane from the channel
Decarburization was performed by injecting oxygen at 220 Nm 3 / hr from the inner channel and propane at 100 Nm 3 / hr from the central channel. 20 minutes after the start of decarburization, the C concentration in the molten steel is 0.13% and the Cr concentration is 16.5%
After 40 minutes from the start, the C concentration in the molten steel was 0.08%, and the Cr concentration was
It was 15.2%. During decarburization refining for 40 minutes, nozzle clogging due to supercooling at the tuyere tip did not occur at all, and refining proceeded stably and smoothly.
【００２７】従来例 従来法として、初期溶鋼条件は同一とし、上吹きランス
より酸素を260 Nm3/hr、底吹き単管羽口よりアルゴンを
260 Nm3/hr吹き込んで脱炭した。この時の脱炭開始20分
後の溶鋼中Ｃ濃度は0.14％、Cr濃度は16.2％であり、脱
炭開始40分後の溶鋼中Ｃ濃度は0.04％、Cr濃度はは15.5
％であった。 Conventional Example As a conventional method, the initial molten steel conditions were the same, oxygen was 260 Nm 3 / hr from the top blowing lance, and argon was from the bottom blowing single tube tuyere.
It was decarburized by blowing it in at 260 Nm 3 / hr. At this time, the C concentration in the molten steel 20 minutes after the start of decarburization was 0.14% and the Cr concentration was 16.2%, and the C concentration in the molten steel 40 minutes after the start of decarburization was 0.04% and the Cr concentration was 15.5%.
%Met.
【００２８】上記結果からわかるように、脱炭開始20分
後では、本発明によりプロパンを酸素と共に吹込んだ方
が、脱炭率がやや高く、Crの酸素ロスはやや低く、高価
なアルゴンを使用した場合に匹敵するか、それよりやや
優れた脱炭効果を得ることができた。しかも、ガスの吹
込み量は、プロパンが合計160 Nm3/hrであるのに対し、
アルゴンは260 Nm3/hrであって、本発明法によるガス吹
込み量はかなり少なかった。As can be seen from the above results, after 20 minutes from the start of decarburization, when propane was blown together with oxygen according to the present invention, the decarburization rate was rather high, the oxygen loss of Cr was rather low, and expensive argon was used. A decarburizing effect comparable to or slightly better than that of the used case could be obtained. Moreover, the total amount of gas blown in is 160 Nm 3 / hr for propane,
Argon was 260 Nm 3 / hr, and the gas injection amount by the method of the present invention was considerably small.
【００２９】実施例２ 実施例１と同様の溶鋼10トンに対して、脱炭開始から20
分間は実施例１と同様の上吹き・底吹き条件で脱炭を行
い、脱炭開始20分後に、底吹き羽口のガスをアルゴン26
0 Nm3/hrに切替え、さらに20分間の脱炭を行った。脱炭
開始20分後の溶鋼中Ｃ濃度は0.12％、Cr濃度は16.7％で
あり、脱炭開始40分後の溶鋼中Ｃ濃度は0.03％、Cr濃度
は16.0％であった。 Example 2 With respect to 10 tons of molten steel as in Example 1, 20 times from the start of decarburization
For minutes, decarburization was carried out under the same top and bottom blowing conditions as in Example 1, and 20 minutes after the start of decarburization, the gas at the bottom blowing tuyere was replaced with argon 26
After switching to 0 Nm 3 / hr, decarburization was performed for 20 minutes. The C concentration in the molten steel 20 minutes after the start of decarburization was 0.12% and the Cr concentration was 16.7%, and the C concentration in the molten steel 40 minutes after the start of decarburization was 0.03% and the Cr concentration was 16.0%.
【００３０】即ち、脱炭途中の溶鋼中Ｃ濃度0.05〜0.20
％の領域で、羽口吹込みガスの炭化水素ガスをアルゴン
に切り換えることで、上記従来法に比べてより低炭素ま
で脱炭でき、しかもクロムの酸化ロスも従来法より少な
かった。また、脱炭の後半にしかアルゴンを使用しなか
ったため、高価なアルゴンの使用量は従来法に比べて半
減した。即ち、この方法によれば、従来法に匹敵する
か、それより高品質ののステンレス鋼を、より少ないク
ロム酸化ロス、かつより低コストで精錬することができ
る。That is, the C concentration in the molten steel during decarburization is 0.05 to 0.20.
%, By switching the hydrocarbon gas of the tuyere blowing gas to argon, it was possible to decarburize to a lower carbon than the above-mentioned conventional method, and the oxidation loss of chromium was smaller than that of the conventional method. Moreover, since argon was used only in the latter half of decarburization, the amount of expensive argon used was halved compared to the conventional method. That is, according to this method, stainless steel having a quality comparable to or higher than that of the conventional method can be refined with less chromium oxidation loss and at lower cost.
【００３１】実施例３ 実施例１と同様の溶鋼10トンに対して、上吹きランスよ
り酸素を150 Nm3/hr、同心円状二重管構造の羽口の外側
流路よりメタンを20 Nm3/hr とアルゴンを20 Nm3/hr 、
中心の流路より酸素を120 Nm3/hrとアルゴンを40 Nm3/h
r 吹き込んで、35分間の脱炭を行った。脱炭後の溶鋼中
Ｃ濃度は0.04％、Cr濃度は15.9％であった。 Example 3 With respect to 10 tons of molten steel similar to that in Example 1, 150 Nm 3 / hr of oxygen was supplied from the top blowing lance, and 20 Nm 3 of methane was supplied from the outer passage of the tuyere of the concentric double tube structure. / hr and Argon at 20 Nm 3 / hr,
120 Nm 3 / hr of oxygen and 40 Nm 3 / h of argon from the central channel
r It was blown in and decarburized for 35 minutes. After decarburization, the C concentration in the molten steel was 0.04% and the Cr concentration was 15.9%.
【００３２】本実施例では、アルゴンを炭化水素ガス
(メタン) および酸素の両方に混入し、メタンの吹込み
量が少なかったため、二重管羽口でも過冷却によるノズ
ル詰まりを起こさずに脱炭することができた。上記従来
法では、アルゴンの吹込み量は酸素吹込み量と同量であ
ったが、本実施例では比較的少量の炭化水素ガスをアル
ゴンと一緒に吹込むことで、アルゴンの吹込み量を酸素
吹込み量の半分にすることができ、この場合にもアルゴ
ンの使用量を従来法に比べて半減することができた。し
かも、従来法より短い脱炭時間で従来法に匹敵する脱炭
成績を得ることができた。以上の各実施例および従来例
の結果を次の表１にまとめて示す。In this embodiment, argon is used as the hydrocarbon gas.
Since it was mixed with both (methane) and oxygen and the amount of methane blown was small, decarburization was possible even with double tube tuyeres without causing nozzle clogging due to supercooling. In the above conventional method, the amount of argon blown was the same as the amount of oxygen blown, but in the present embodiment, by blowing a relatively small amount of hydrocarbon gas together with argon, the amount of argon blown It was possible to halve the amount of oxygen blown in, and in this case as well, the amount of argon used could be halved compared to the conventional method. Moreover, decarburization results comparable to those of the conventional method could be obtained with a shorter decarburization time than that of the conventional method. The results of each of the above examples and the conventional example are summarized in Table 1 below.
【００３３】[0033]
【表１】 [Table 1]
【００３４】[0034]
【発明の効果】本発明により、高価なアルゴンを全く使
用せず、或いはその使用量を大幅に低減して、クロムの
酸化ロスを防いでステンレス鋼などのクロム含有溶鋼の
効率的な脱炭精錬を行うことが可能となる。従って、本
発明はステンレス鋼のコスト低減に大きく寄与する技術
である。EFFECTS OF THE INVENTION According to the present invention, expensive argon is not used at all or the amount thereof is greatly reduced to prevent oxidation loss of chromium and to efficiently decarburize and refine molten steel containing chromium such as stainless steel. It becomes possible to do. Therefore, the present invention is a technique that greatly contributes to cost reduction of stainless steel.
【図１】本発明で使用する三重管羽口の断面図である。FIG. 1 is a cross-sectional view of a triple tube tuyere used in the present invention.
1: 最外管流路 (炭化水素用) 2: 内側の流路 (酸素用) 3: 中心流路 (炭化水素用） 1: Outermost pipe channel (for hydrocarbon) 2: Inner channel (for oxygen) 3: Central channel (for hydrocarbon)
Claims (3)
吹込まずに、溶鋼浴面下において羽口より炭化水素ガス
を酸素および／または不活性ガスと同時に溶鋼中に吹込
むことを特徴とする、クロム含有溶鋼の脱炭精錬方法。1. A method for injecting oxygen from a top-blowing lance, or, without injecting oxygen, a hydrocarbon gas is blown into the molten steel from the tuyere under the surface of the molten steel simultaneously with oxygen and / or an inert gas. , Decarburization refining method for molten steel containing chromium.
ており、最も外側の流路より炭化水素ガスを、その内側
の流路より酸素を、中心の流路より炭化水素ガスを吹き
込むことを特徴とする請求項１記載の方法。2. The tuyere has a concentric triple tube structure, and hydrocarbon gas is supplied from the outermost flow path, oxygen is supplied from the inner flow path, and hydrocarbon gas is supplied from the central flow path. The method of claim 1, wherein the method comprises blowing.
囲内に低下するまでは請求項１記載の方法で精錬し、次
いで羽口よりの吹込みガスを酸素と不活性ガスとに切り
換えて精錬を続けることを特徴とする、クロム含有溶鋼
の脱炭精錬方法。3. Refining by the method according to claim 1 until the carbon concentration of the molten steel falls within the range of 0.05 to 0.20% by weight, and then the gas blown from the tuyere is switched to oxygen and inert gas. A method for decarburizing and refining molten steel containing chromium, which comprises continuously refining the steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4296086A JP3063431B2 (en) | 1992-11-05 | 1992-11-05 | Decarburization refining method of molten steel containing chromium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4296086A JP3063431B2 (en) | 1992-11-05 | 1992-11-05 | Decarburization refining method of molten steel containing chromium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06145762A true JPH06145762A (en) | 1994-05-27 |
| JP3063431B2 JP3063431B2 (en) | 2000-07-12 |
Family
ID=17828941
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4296086A Expired - Lifetime JP3063431B2 (en) | 1992-11-05 | 1992-11-05 | Decarburization refining method of molten steel containing chromium |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100363417B1 (en) * | 1998-12-09 | 2003-01-24 | 주식회사 포스코 | Decarburization of Low Carbon Stainless Steel |
| KR100384119B1 (en) * | 1996-07-29 | 2003-08-21 | 주식회사 포스코 | Method for refining stainless steel containing low carbon and low nitrogen |
| KR100406387B1 (en) * | 1996-12-14 | 2004-03-19 | 주식회사 포스코 | Method for decarburizing stainless steel by argon oxygen decarburization |
| KR100922058B1 (en) * | 2007-12-20 | 2009-10-16 | 주식회사 포스코 | Method for refining the ferrit stainless hot metal having high Cr |
-
1992
- 1992-11-05 JP JP4296086A patent/JP3063431B2/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100384119B1 (en) * | 1996-07-29 | 2003-08-21 | 주식회사 포스코 | Method for refining stainless steel containing low carbon and low nitrogen |
| KR100406387B1 (en) * | 1996-12-14 | 2004-03-19 | 주식회사 포스코 | Method for decarburizing stainless steel by argon oxygen decarburization |
| KR100363417B1 (en) * | 1998-12-09 | 2003-01-24 | 주식회사 포스코 | Decarburization of Low Carbon Stainless Steel |
| KR100922058B1 (en) * | 2007-12-20 | 2009-10-16 | 주식회사 포스코 | Method for refining the ferrit stainless hot metal having high Cr |
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| Publication number | Publication date |
|---|---|
| JP3063431B2 (en) | 2000-07-12 |
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