JP2007224387A - Ladle-refining method and ladle-refining furnace - Google Patents

Ladle-refining method and ladle-refining furnace Download PDF

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JP2007224387A
JP2007224387A JP2006048705A JP2006048705A JP2007224387A JP 2007224387 A JP2007224387 A JP 2007224387A JP 2006048705 A JP2006048705 A JP 2006048705A JP 2006048705 A JP2006048705 A JP 2006048705A JP 2007224387 A JP2007224387 A JP 2007224387A
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ladle
molten steel
inert gas
stirring
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JP4816138B2 (en
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Kenji Oshima
健二 大島
Daisuke Takahashi
大輔 高橋
Shingo Fujiwara
真吾 藤原
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JFE Steel Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for surely achieving floatation separation of inclusions and for suitably performing desulfurization in a ladle-refining furnace which is considered as the disadvantage, regarding floatation separation of fine inclusions in the conventional method. <P>SOLUTION: When molten steel in the ladle-refining furnace is refined by stirring with usages of both the blowing of an inert gas from the bottom part of the ladle and the electromagnetic stirring, during degassing treatment, the molten steel fluidization with the electromagnetic stirring is introduced so as to ascend along the inner wall of the ladle and descend in the inert gas ascending area. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、取鍋精錬方法並びに取鍋精錬炉に関し、特に不活性ガスの吹き込みと電磁攪拌とを併用して溶鋼の攪拌を行う際に、非金属介在物の浮上を有利に実現する取鍋精錬方法に関するものである。   The present invention relates to a ladle refining method and a ladle refining furnace, and more particularly to a ladle that advantageously realizes floating of non-metallic inclusions when performing stirring of molten steel by using both inert gas blowing and electromagnetic stirring. It relates to the refining method.

製鋼工程において、溶鋼中に含まれる非金属介在物（以下「介在物」と記す）を浮上分離させて減量することは、良好な製品品質を維持する上で重要である。また、溶鋼中の［Ｓ］を除去する脱硫操作も製品品質を維持する上で重要である。   In the steel making process, it is important to maintain the good product quality by floating and separating the nonmetallic inclusions (hereinafter referred to as “inclusions”) contained in the molten steel. In addition, a desulfurization operation for removing [S] in molten steel is also important in maintaining product quality.

例えば、溶鋼の精錬過程で溶鋼中の酸素を脱酸する工程があり、この脱酸工程では、溶鋼中に多数の酸化物系介在物が生成する。ここで生成する介在物の大半は、径が10μm以下と小さく、溶鋼との比重差に基づく介在物自体の有する浮上速度は１×10−５ｍ／ｓ程度であり、この浮上速度で溶鋼湯面まで浮上するには、数時間を要する。さらに、取鍋内の溶鋼中には、移動速度が１×10−２ｍ／ｓ程度で、幅が１ｍ以下の熱対流セルが存在するため、介在物の浮上分離はますます難しくなる。そのために、介在物の浮上分離を促進させる方法が種々提案されてきた。 For example, there is a step of deoxidizing oxygen in the molten steel during the refining process of the molten steel, and in this deoxidation step, a large number of oxide inclusions are generated in the molten steel. Most of the inclusions produced here have a small diameter of 10 μm or less, and the floating speed of the inclusion itself based on the difference in specific gravity from the molten steel is about 1 × 10 −5 m / s. It takes several hours to rise to the surface. Furthermore, in the molten steel in the ladle, there is a thermal convection cell with a moving speed of about 1 × 10 −2 m / s and a width of 1 m or less, so that the floating separation of inclusions becomes more difficult. Therefore, various methods for promoting the floating separation of inclusions have been proposed.

その一つとして、磁場が鉛直方向に移動する電磁攪拌装置（移動磁場発生装置とも言う）を取鍋の側面に取り付け、取鍋内の溶鋼を鉛直方向に攪拌する取鍋精錬法（例えば、ASEA−SKF法）がある。この方法では、電磁攪拌装置により取鍋内の溶鋼に鉛直方向の循環流を励起するため、強い循環流が得られる。しかし、このような電磁攪拌装置は、取鍋のハンドリングや設備コストの点から取鍋の側壁全周に配置されることはなく、通常、側壁周方向の一部分のみに設置されて攪拌を行うことになる。従って、取鍋内の溶鋼湯面では、電磁攪拌装置が設置された部分だけに強い湧昇流が生じるため、この湧昇流により溶鋼湯面に浮かんでいるスラグが溶鋼中に巻き込まれ、このスラグが介在物となることもある。   As one of them, a ladle refining method (for example, ASEA) in which a magnetic stirrer (also called a moving magnetic field generator) in which the magnetic field moves in the vertical direction is attached to the side of the ladle and the molten steel in the ladle is stirred in the vertical direction. -SKF method). In this method, a strong circulating flow is obtained because the vertical circulating flow is excited in the molten steel in the ladle by the electromagnetic stirring device. However, such an electromagnetic stirrer is not placed on the entire circumference of the ladle side wall from the viewpoint of ladle handling and equipment costs, and is usually installed only in a part of the side wall circumferential direction for stirring. become. Therefore, on the molten steel surface in the ladle, a strong upwelling flow is generated only in the part where the electromagnetic stirrer is installed, so that the slag floating on the molten steel surface is caught in the molten steel by this upwelling flow. Slag can be an inclusion.

かような問題を回避するために、取鍋側方に電磁攪拌装置を持つ技術において、溶鋼に回転流を与えて攪拌することが、特許文献１ないし３に記載されている。しかしながら、これら技術をもってしても、介在物の浮上分離においては未だ問題を残していた。   In order to avoid such a problem, Patent Documents 1 to 3 describe that, in a technique having an electromagnetic stirring device on the side of a ladle, stirring is performed by giving a rotating flow to molten steel. However, even with these techniques, problems still remain in the floating separation of inclusions.

すなわち、介在物浮上分離のための攪拌時間を長くとっても鋼中介在物、とりわけ微細介在物の減少につながらないという問題である。
特公表64−500526号公報 特開平４−48027号公報 特開2002−153944号公報 That is, there is a problem that even if the stirring time for inclusion floating separation is increased, inclusions in steel, particularly fine inclusions, are not reduced.
Special Publication No. 64-500526 Japanese Patent Laid-Open No. 4-48027 Japanese Patent Laid-Open No. 2002-153944

そこで、本発明は、従来は微細介在物の分離の点で不利とされていた取鍋精錬炉においても介在物の浮上分離を確実に実現し、さらには脱硫を適切に行うための方途について提案することを目的とする。   Therefore, the present invention proposes a method for reliably realizing the floating separation of inclusions even in a ladle refining furnace, which has conventionally been disadvantageous in terms of separation of fine inclusions, and further appropriately performing desulfurization. The purpose is to do.

発明者等は、上記課題を解決するための手段について鋭意検討したところ、攪拌のための気泡を微細化することによって、介在物の浮上力が強化されて介在物の浮上分離を確実に行えること、また、脱硫処理においては、脱硫剤との強攪拌を実現することによって、処理時間の短縮および脱硫能の向上がはかれること、を見出し、本発明を完成するに到った。   As a result of diligent research on the means for solving the above problems, the inventors have made it possible to enhance the floating force of inclusions and reliably perform the floating separation of inclusions by refining the bubbles for stirring. Further, in the desulfurization treatment, the inventors have found that the treatment time can be shortened and the desulfurization ability can be improved by realizing strong stirring with the desulfurization agent, and the present invention has been completed.

すなわち、本発明の要旨は、次のとおりである。
（１）取鍋精錬炉内の溶鋼を、該取鍋底部からの不活性ガスの吹き込み並びに電磁攪拌の併用により攪拌して精錬を行うに当り、脱ガス処理時は、電磁攪拌による溶鋼流動を、取鍋内壁に沿って上昇し前記不活性ガス上昇領域にて下降する向きに誘導することを特徴とする取鍋精錬方法。 That is, the gist of the present invention is as follows.
(1) When the molten steel in the ladle refining furnace is smelted by injecting inert gas from the bottom of the ladle and using electromagnetic stirring together, the molten steel flows by electromagnetic stirring during degassing. A ladle refining method, wherein the ladle is guided along a ladle inner wall and guided in a direction to descend in the inert gas ascending region.

（２）取鍋精錬炉内の溶鋼を、該取鍋底部からの不活性ガスの吹き込み並びに電磁攪拌の併用により攪拌して精錬を行うに当り、脱硫処理時は、電磁攪拌による溶鋼流動を、取鍋内壁に沿って下降し前記不活性ガス上昇領域にて上昇する向きに誘導することを特徴とする取鍋精錬方法。 (2) When the molten steel in the ladle refining furnace is smelted by using inert gas blowing from the bottom of the ladle and using electromagnetic stirring, the molten steel flow by electromagnetic stirring is A ladle refining method, wherein the ladle refining method is guided along a ladle inner wall and descending in the inert gas ascending region.

（３）取鍋に、該取鍋内の溶鋼に流動を与える電磁攪拌装置、取鍋の底部から不活性ガスを吹き込む不活性ガス供給装置、取鍋内の溶鋼を加熱する溶鋼加熱装置および、脱ガス装置を装着してなる取鍋精錬炉。 (3) An electromagnetic stirrer that gives flow to the molten steel in the ladle, an inert gas supply device that blows inert gas from the bottom of the ladle, a molten steel heating device that heats the molten steel in the ladle, and A ladle refining furnace equipped with a degasser.

本発明によれば、介在物の分離除去を行う脱ガス処理時は、電磁攪拌による溶鋼流動を、取鍋内壁に沿って上昇し不活性ガス上昇領域にて下降する向きに誘導するために、取鍋底部より供給される不活性ガスおよび溶鋼中から生起する気泡の浮上を、電磁攪拌による溶鋼流動が妨げる結果、上記気泡は微細な気泡となって上昇することになり、微細気泡により溶鋼中の介在物の浮上促進が実現される。   According to the present invention, during the degassing treatment for separating and removing inclusions, in order to induce the molten steel flow by electromagnetic stirring to rise in the ladle inner wall and to descend in the inert gas rising region, Inert gas supplied from the bottom of the ladle and bubbles rising from the molten steel are hindered by the flow of molten steel by electromagnetic stirring. As a result, the bubbles rise as fine bubbles. Promotion of floating of inclusions is realized.

また、本発明によれば、脱硫処理時は上記脱ガス処理時とは逆に、電磁攪拌による溶鋼流動を、取鍋内壁に沿って下降し不活性ガス上昇領域にて上昇する向きに誘導するために、この溶鋼流動と取鍋底部より供給される不活性ガスの上昇方向とが一致して強い流動を溶鋼に与えることになる結果、脱硫剤との攪拌は強化され、脱硫時間の短縮および脱硫効率の向上が実現される。   Further, according to the present invention, at the time of desulfurization treatment, contrary to the above-mentioned degassing treatment, the flow of molten steel by electromagnetic stirring is induced to descend along the ladle inner wall and rise in the inert gas rising region. Therefore, the flow of the molten steel and the rising direction of the inert gas supplied from the bottom of the ladle coincide with each other and give a strong flow to the molten steel. As a result, the stirring with the desulfurizing agent is strengthened, and the desulfurization time is shortened. Improvement of desulfurization efficiency is realized.

さらに、本発明の取鍋精錬炉では、大きな改造を施すことなく簡単な構成の下に、上記した溶鋼の効果的な攪拌を可能とする。   Furthermore, in the ladle refining furnace of the present invention, the above-described molten steel can be effectively stirred with a simple configuration without any major modification.

以下、図１ないし４を参照して、従来手法との対比によって本発明を詳しく説明する。これら図１ないし４において、取鍋精錬炉の基本構成は同じであり、図中、符号１は取鍋、２は溶鋼に流動を与える電磁攪拌装置、３は取鍋１底部に設けられた不活性ガスを供給するポーラスプラグを示す。   Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 4, the basic structure of the ladle refining furnace is the same. The porous plug which supplies active gas is shown.

取鍋精錬炉における脱ガス処理時の溶鋼の攪拌について、まず、従来方式を図１に示す。すなわち、取鍋１側方に配置した電磁攪拌装置２によって、溶鋼４に下降流５を生起させる。この下降流５は、取鍋１の底部で反転して、６の上昇流となって溶鋼４の攪拌がはかられる。   Regarding the stirring of molten steel during degassing treatment in a ladle refining furnace, first, a conventional method is shown in FIG. That is, the downward flow 5 is caused in the molten steel 4 by the electromagnetic stirring device 2 arranged on the side of the ladle 1. This downward flow 5 is reversed at the bottom of the ladle 1 and becomes an upward flow 6 to stir the molten steel 4.

そして、この上昇流６の流動と、前記ポーラスプラグ３からの不活性ガスの供給で発生した気泡７による上昇流動を一致させ、脱ガス、そして介在物の浮上を速やかに図るものであった。   Then, the flow of the upward flow 6 and the upward flow caused by the bubbles 7 generated by the supply of the inert gas from the porous plug 3 are matched to degas and raise the inclusions promptly.

この従来の攪拌方法は、不活性ガスの気泡７によるリンス効果および溶鋼４中の脱ガスと、強力な上昇流による速やかな脱ガスおよび介在物の浮上とを所期したものであり、十分な効果を発揮していた。しかしながら、近年、介在物は例えば５μm以下の径の微細なものまでを問題としており、従来の攪拌形態が不十分であるとの問題意識はここに端を発している。   This conventional stirring method is intended for the rinsing effect by the bubbles 7 of the inert gas, the degassing in the molten steel 4, the quick degassing by the strong upward flow, and the floating of the inclusions. It was effective. However, in recent years, inclusions have become a problem with fine inclusions having a diameter of, for example, 5 μm or less, and the awareness of the problem that the conventional stirring mode is insufficient originates here.

すなわち、従来の攪拌形態の問題として、ポーラスプラグ３からの不活性ガスの供給に伴う気泡７の上昇により、介在物の浮上も合わせて行われるが、気泡径が大きいために大型介在物の浮上には有効であったが、微細介在物を随伴する十分な流動になっていないことおよび、気泡７の上昇力と上昇流６の一致による上昇流動が溶鋼表面で強い反転流となって、浮上した介在物が溶鋼４中へ再度巻き込まれること、が新たに判明した。   That is, as a problem of the conventional agitation mode, the inclusions rise due to the rise of the bubbles 7 accompanying the supply of the inert gas from the porous plug 3, but the large inclusions rise due to the large bubble diameter. However, the flow is not sufficient with fine inclusions, and the rising flow due to the coincidence of the rising force of the bubbles 7 and the rising flow 6 becomes a strong reversal flow on the surface of the molten steel. It has been newly found that the inclusions that have been trapped in the molten steel 4 again.

そこで、従来の発想とは逆転する方法を試みたのが、図２に示す本発明に従う取鍋精錬炉における溶鋼の攪拌方法である。
図２に示すように、本発明では、真空脱ガス時の溶鋼攪拌において、取鍋１側方に配置した電磁攪拌装置２によって、溶鋼４に従来方式とは逆に、上昇流11を生起させる。この上昇流11は、取鍋１内の溶鋼表層部で反転して、取鍋１中央を下降する12の下降流となる。本発明では、この下降流12によって、ポーラスプラグ３からの不活性ガス供給に伴う気泡７の上昇を妨げつつ脱ガス処理を行う。 Therefore, the method of agitating molten steel in the ladle refining furnace according to the present invention shown in FIG.
As shown in FIG. 2, in the present invention, in the molten steel stirring during vacuum degassing, an upward flow 11 is generated in the molten steel 4, contrary to the conventional method, by the electromagnetic stirring device 2 disposed on the side of the ladle 1. . This upward flow 11 is reversed at the surface layer of the molten steel in the ladle 1 and becomes a downward flow 12 which descends in the center of the ladle 1. In the present invention, the downflow 12 performs the degassing process while preventing the bubbles 7 from rising due to the inert gas supply from the porous plug 3.

すなわち、従来の問題点は、不活性ガス供給に伴う気泡の径が大きいために大型介在物の除去には効果的であっても、溶鋼中に分散して存在する微細介在物を随伴する十分な流動になっていないことおよび、浮上した介在物が溶鋼４中へ再度巻き込まれることにあるのは、上述とおりである。従って、本発明では上昇するポーラスプラグ３からの不活性ガス供給に伴う気泡７に、下降流12を衝突させて気泡７の細分化を行うこととした。気泡７を細分化させ、溶鋼４中の全域に分散させることにより、微細介在物の捕捉、浮上分離を図るのである。   That is, the conventional problem is that it is effective for removing large inclusions due to the large bubble diameter associated with the inert gas supply, but it is sufficiently accompanied by fine inclusions dispersed in the molten steel. As described above, the flow does not become a proper flow and the inclusions that have floated up are re-rolled into the molten steel 4. Accordingly, in the present invention, the bubbles 7 are subdivided by colliding the descending flow 12 with the bubbles 7 accompanying the inert gas supply from the rising porous plug 3. By subdividing the bubbles 7 and dispersing them throughout the molten steel 4, the fine inclusions are captured and separated by floating.

かように、図１の従来方式とは逆転する向きに溶鋼の流動を与えることによって、気泡７は微細化されて溶鋼４中を上昇する為、微細介在物までを浮上させることができ、また、図１と異なり反転流を低く抑えられるため、再巻き込みも阻止することができる。   Thus, by giving the flow of the molten steel in the direction opposite to that of the conventional method of FIG. 1, the bubbles 7 are refined and rise in the molten steel 4, so that even fine inclusions can be levitated. Unlike the case of FIG. 1, since the reversal flow can be kept low, re-entrainment can be prevented.

この脱ガス処理における不活性ガスの供給量は、溶鋼装入量：30〜100ｔ取鍋で50〜150ｌ／min、また電磁攪拌条件は、印加電流値：900〜1100Ａである。   The supply amount of the inert gas in this degassing treatment is 50 to 150 l / min in the molten steel charging amount: 30 to 100 t ladle, and the electromagnetic stirring condition is the applied current value: 900 to 1100 A.

次に、図３は、従来の取鍋精錬炉における脱硫時の溶鋼攪拌形態を示したものであり、取鍋１側方に配置した電磁攪拌装置２によって、溶鋼４に取鍋１の内壁に沿って上昇流８を生起させる。この上昇流８は、取鍋１内の溶鋼表層部で反転して、取鍋１中央を下降する下降流となって溶鋼４の攪拌が行なわれていた。この攪拌方法によって、脱硫時に溶鋼４表面に投入された脱硫剤10は、溶鋼攪拌により生起された下降流９によって界面で反応するとともに、さらに下降流９によって巻き込まれた脱硫剤10の溶鋼４中への分散が不活性ガスの気泡７によって生じ、最も効率的脱硫が図られると考えられていた。
しかし、脱硫はどうしても界面反応が主体になることは避けられず、さらなる脱硫の促進をはかる必要がある。 Next, FIG. 3 shows a molten steel stirring mode at the time of desulfurization in a conventional ladle refining furnace, and the molten steel 4 is attached to the inner wall of the ladle 1 by an electromagnetic stirring device 2 arranged on the side of the ladle 1. The upward flow 8 is caused along. This upward flow 8 was reversed at the surface layer of the molten steel in the ladle 1 and became a downward flow descending the center of the ladle 1 to stir the molten steel 4. By this stirring method, the desulfurizing agent 10 introduced to the surface of the molten steel 4 at the time of desulfurization reacts at the interface by the downward flow 9 generated by the molten steel stirring, and further in the molten steel 4 of the desulfurizing agent 10 entrained by the downward flow 9. It was considered that the most efficient desulfurization was achieved by the dispersion of the gas into the gas by the bubbles 7 of the inert gas.
However, desulfurization inevitably involves an interfacial reaction, and further desulfurization needs to be promoted.

そこで、本発明の脱硫処理時の溶鋼攪拌形態は、図４に示すように、脱硫時の場合もまた、従来の脱硫処理時と逆転する流動を溶鋼に与える。すなわち、図４に示すように、取鍋１側方に配置した電磁攪拌装置２によって、溶鋼４に取鍋１の内壁に沿って下降流13を生起させる。この下降流13は、取鍋１底部で反転して上昇する上昇流14となる。   Therefore, as shown in FIG. 4, the molten steel stirring mode during the desulfurization treatment of the present invention gives the molten steel a flow reverse to that during the conventional desulfurization treatment in the case of desulfurization. That is, as shown in FIG. 4, a downward flow 13 is caused in the molten steel 4 along the inner wall of the ladle 1 by the electromagnetic stirring device 2 arranged on the side of the ladle 1. This downward flow 13 becomes an upward flow 14 that reverses and rises at the bottom of the ladle 1.

従って、本発明に従う脱硫処理時は、ポーラスプラグ３からの不活性ガス供給に伴う気泡７の上昇方向と、上昇流14との向きが一致するのである。   Therefore, during the desulfurization treatment according to the present invention, the upward direction of the bubbles 7 accompanying the supply of the inert gas from the porous plug 3 coincides with the direction of the upward flow 14.

この気泡７の上昇と溶鋼流動の一致化により、取鍋１内の溶鋼４の中央部に強力な上昇流が発生し、溶鋼４表面に投入された脱硫剤10は、取鍋４の側壁に沿って溶鋼４中に巻き込まれ、あるいは溶鋼湯面の表層にて溶鋼４と脱硫剤10とが混合、攪拌される結果、脱硫が進行する。
そのため、界面反応が主体であった従来の脱硫処理と比べて、本発明に従う攪拌方法では脱硫時間を半減できる顕著な効果を発揮する。 Due to the coincidence of the rise of the bubbles 7 and the flow of the molten steel, a strong upward flow is generated at the center of the molten steel 4 in the ladle 1, and the desulfurizing agent 10 introduced to the surface of the molten steel 4 is placed on the side wall of the ladle 4. As a result, the molten steel 4 and the desulfurizing agent 10 are mixed and stirred in the surface layer of the molten steel surface as a result of desulfurization.
Therefore, compared with the conventional desulfurization treatment in which the interfacial reaction is mainly performed, the stirring method according to the present invention exhibits a remarkable effect that the desulfurization time can be halved.

この脱硫処理における不活性ガスの供給量は、溶鋼装入量：30〜100ｔ取鍋で150〜250ｌ／min、また電磁攪拌条件は、印加電流値：1000〜1200Ａである。脱ガス処理時より溶鋼を強攪拌するために、不活性ガス供給量は増加及び電磁攪拌条件は印加電流値を増加した。   The supply amount of the inert gas in this desulfurization treatment is 150 to 250 l / min in the molten steel charging amount: 30 to 100 t ladle, and the electromagnetic stirring condition is the applied current value: 1000 to 1200 A. In order to strongly stir the molten steel from the time of degassing treatment, the inert gas supply amount increased and the electromagnetic stirring condition increased the applied current value.

以上の脱ガス処理および脱硫処理を行う取鍋精錬炉としては、図１ないし４に示した取鍋１に、電磁攪拌装置２およびポーラスプラグ３のほか、図５に示すように、このポーラスプラグ３に接続されて取鍋の底部から不活性ガスを吹き込む不活性ガス供給装置15および取鍋１内の溶鋼４を加熱する溶鋼加熱装置16および、脱ガス装置17を装着してなるものが適合する。なお、図５に示した取鍋精錬炉では、溶鋼加熱装置16および脱ガス装置17を取鍋容器の蓋形式で装着し、原料並びに溶鋼の加熱段階では溶鋼加熱装置16を装着（図５（ａ）参照）し、その後の脱ガス処理そして脱硫処理の段階では脱ガス装置17を装着（図５（ｂ）参照）する使用形態をとる。
そして、脱ガス時と脱硫時に合せて、不活性ガス供給装置15はガス供給量が制御可能であり、電磁攪拌装置２も流動方向を切換え可能である。 As a ladle refining furnace for performing the above degassing treatment and desulfurization treatment, in addition to the electromagnetic stirring device 2 and the porous plug 3 in addition to the ladle 1 shown in FIGS. 3 is connected to 3 which is equipped with an inert gas supply device 15 for blowing inert gas from the bottom of the ladle, a molten steel heating device 16 for heating the molten steel 4 in the ladle 1, and a degassing device 17 To do. In the ladle refining furnace shown in FIG. 5, the molten steel heating device 16 and the degassing device 17 are mounted in the form of a ladle vessel lid, and the molten steel heating device 16 is mounted in the raw material and molten steel heating stage (FIG. 5 ( a)), and in the subsequent degassing and desulfurization stages, a degassing device 17 is mounted (see FIG. 5B).
Then, in accordance with the degassing and desulfurization, the inert gas supply device 15 can control the gas supply amount, and the electromagnetic stirring device 2 can also switch the flow direction.

転炉から取鍋（容量：30〜100ｔ）に出鋼された、Ｃ：0.05mass％、Mn：0.06mass％、Ｐ：0.006mass％、Ｓ：0.002mass％、Ｎ：0.0025mass％およびＯ：0.0300mass％を含み、残部Feおよび不可避的不純物の成分組成を有する溶鋼に、真空脱ガス処理並びに脱硫処理を施して、Ｃ：0.10mass％、Si：0.4mass％、Mn：0.4mass％、Ｐ：0.010mass％、Ｓ：0.0008mass％、Al：0.001mass％、Cu：0.05mass％、Ni：0.1mass％、Cr：8.55mass％Mo：0.97mass％、Ｖ：0.19mass％、Nb：0.08mass％、Ｎ：0.0400mass％およびＯ：0.007mass％を含み、残部Feおよび不可避的不純物の成分組成とする、精錬を行った。   C: 0.05 mass%, Mn: 0.06 mass%, P: 0.006 mass%, S: 0.002 mass%, N: 0.0025 mass%, and O: steel discharged from the converter to the ladle (capacity: 30 to 100 t) The molten steel containing 0.0300 mass% and having the balance Fe and inevitable impurities component composition is subjected to vacuum degassing treatment and desulfurization treatment. C: 0.10 mass%, Si: 0.4 mass%, Mn: 0.4 mass%, P : 0.010 mass%, S: 0.0008 mass%, Al: 0.001 mass%, Cu: 0.05 mass%, Ni: 0.1 mass%, Cr: 8.55 mass% Mo: 0.97 mass%, V: 0.19 mass%, Nb: 0.08 mass And N: 0.0400 mass% and O: 0.007 mass%, and the refining was performed with the composition of the remaining Fe and inevitable impurities.

すなわち、取鍋に転炉からの溶鋼を装入したのち、溶鋼加熱、脱ガス処理、脱硫処理および成分・温度調整の工程からなる精錬を、下記の条件に従って行った。以下は、いずれも溶鋼100ｔ例である。   That is, after charging the molten steel from the converter into the ladle, refining comprising the steps of molten steel heating, degassing treatment, desulfurization treatment and component / temperature adjustment was performed according to the following conditions. The following are examples of 100 t of molten steel.

記
［比較例］
脱ガス処理：図１に示すところに従って、電磁攪拌装置２による溶鋼の流動を導くと共に、鍋底のポーラスプラグからアルゴンガスの供給を行った。この電磁攪拌条件は、印加電流値：900Ａとして取鍋中央部で上昇流を生起させ、またアルゴンガスの供給条件は100ｌ／minとした。
脱硫処理：図３に示すところに従って、電磁攪拌装置２による溶鋼の流動を導くと共に、鍋底のポーラスプラグからアルゴンガスの供給を行った。この電磁攪拌条件は、印加電流値：1000Ａとして取鍋中央部で下降流を生起させ、またアルゴンガスの供給条件は250ｌ／minとした。 [Comparative example]
Degassing treatment: As shown in FIG. 1, the flow of molten steel was guided by the electromagnetic stirring device 2, and argon gas was supplied from the porous plug at the bottom of the pan. The electromagnetic stirring conditions were an applied current value of 900 A, an upward flow was generated in the center of the ladle, and the argon gas supply conditions were 100 l / min.
Desulfurization treatment: As shown in FIG. 3, the flow of molten steel was guided by the electromagnetic stirrer 2 and argon gas was supplied from a porous plug at the bottom of the pan. The electromagnetic stirring conditions were an applied current value of 1000 A and a downward flow was generated in the center of the ladle, and the argon gas supply conditions were 250 l / min.

［発明例］
脱ガス処理：図２に示すところに従って、電磁攪拌装置２による溶鋼の流動を導くと共に、鍋底のポーラスプラグからアルゴンガスの供給を行った。この電磁攪拌条件は、印加電流値：1000Ａとして取鍋中央部で比較例より強い下降流を生起させ、またアルゴンガスの供給条件は150ｌ／minと比較例より増加させ、ガス気泡の増加を図った。
脱硫処理：図４に示すところに従って、電磁攪拌装置２による溶鋼の流動を導くと共に、鍋底のポーラスプラグからアルゴンガスの供給を行った。この電磁攪拌条件は、印加電流値：1000Ａとして取鍋中央部で上昇流を生起させた。また、アルゴンガスの供給条件は、200ｌ／minとして比較例より低下させ、取鍋蓋付着物の多量発生を抑制した。
なお、脱硫剤には、CaＯ-SiＯ2-Al2Ｏ3系フラックスを用いた。 [Invention Example]
Degassing treatment: As shown in FIG. 2, the flow of molten steel was guided by the electromagnetic stirrer 2, and argon gas was supplied from a porous plug at the bottom of the pan. This electromagnetic stirring condition is an applied current value of 1000 A, causing a stronger downward flow in the center of the ladle than in the comparative example, and the argon gas supply condition is increased to 150 l / min from the comparative example to increase gas bubbles. It was.
Desulfurization treatment: As shown in FIG. 4, molten steel flow was guided by the electromagnetic stirring device 2, and argon gas was supplied from a porous plug at the bottom of the pan. Under this electromagnetic stirring condition, the applied current value was 1000 A, and an upward flow was caused in the center of the ladle. In addition, the argon gas supply condition was set to 200 l / min, which was lower than that of the comparative example, and a large amount of ladle cover deposits was suppressed.
Note that a CaO—SiO 2 —Al 2 O 3 flux was used as the desulfurizing agent.

上記した各精錬操業に関して、その精錬時間および製品の内部探傷試験による合格率について調査した。すなわち、精錬時間は、従来法と比較して35％もの短縮が図られ、製品の内部探傷試験による合格率は同一脱ガス時間で40％向上した。   About each refining operation mentioned above, the refining time and the pass rate by the internal flaw test of a product were investigated. In other words, the refining time was shortened by 35% compared to the conventional method, and the acceptance rate by the internal flaw detection test of the product was improved by 40% with the same degassing time.

脱ガス処理における従来の溶鋼の攪拌方向を示す図である。It is a figure which shows the stirring direction of the conventional molten steel in a degassing process. 脱ガス処理における本発明に従う溶鋼の攪拌方向を示す図である。It is a figure which shows the stirring direction of the molten steel according to this invention in a degassing process. 脱硫処理における従来の溶鋼の攪拌方向を示す図である。It is a figure which shows the stirring direction of the conventional molten steel in a desulfurization process. 脱硫処理における本発明に従う溶鋼の攪拌方向を示す図である。It is a figure which shows the stirring direction of the molten steel according to this invention in a desulfurization process. 取鍋精錬炉を示す図である。It is a figure which shows the ladle refining furnace.

符号の説明Explanation of symbols

１ 取鍋
２ 電磁攪拌装置
３ ポーラスプラグ
４ 溶鋼
５ 下降流
６ 上昇流
７ 気泡
８ 上昇流
９ 下降流
１０ 脱硫剤
１１ 上昇流
１２ 下降流
１３ 下降流
１４ 上昇流
１５ 不活性ガス供給装置
１６ 溶鋼加熱装置
１７ 脱ガス装置 DESCRIPTION OF SYMBOLS 1 Ladle 2 Electromagnetic stirring apparatus 3 Porous plug 4 Molten steel 5 Downflow 6 Upflow 7 Bubble 8 Upflow 9 Downflow 10 Desulfurization agent 11 Upflow 12 Downflow 13 Downflow 14 Upflow 15 Inert gas supply device 16 Molten steel heating Device 17 Degassing device

Claims (3)

取鍋精錬炉内の溶鋼を、該取鍋底部からの不活性ガスの吹き込み並びに電磁攪拌の併用により攪拌して精錬を行うに当り、脱ガス処理時は、電磁攪拌による溶鋼流動を、取鍋内壁に沿って上昇し前記不活性ガス上昇領域にて下降する向きに誘導することを特徴とする取鍋精錬方法。   When refining the molten steel in the ladle refining furnace by stirring with both inert gas blowing from the bottom of the ladle and electromagnetic stirring, during the degassing process, A ladle refining method, wherein the ladle refining method is guided along a direction of rising along an inner wall and descending in the inert gas rising region. 取鍋精錬炉内の溶鋼を、該取鍋底部からの不活性ガスの吹き込み並びに電磁攪拌の併用により攪拌して精錬を行うに当り、脱硫処理時は、電磁攪拌による溶鋼流動を、取鍋内壁に沿って下降し前記不活性ガス上昇領域にて上昇する向きに誘導することを特徴とする取鍋精錬方法。   When refining the molten steel in the ladle refining furnace by stirring with both inert gas blowing from the bottom of the ladle and electromagnetic stirring, during the desulfurization treatment, the molten steel flow due to electromagnetic stirring is The ladle refining method is characterized in that the ladle is guided in a direction that descends along the inert gas and rises in the inert gas ascending region. 取鍋に、該取鍋内の溶鋼に流動を与える電磁攪拌装置、取鍋の底部から不活性ガスを吹き込む不活性ガス供給装置、取鍋内の溶鋼を加熱する溶鋼加熱装置および、脱ガス装置を装着してなる取鍋精錬炉。   An electromagnetic stirrer that gives flow to the molten steel in the ladle, an inert gas supply device that blows inert gas from the bottom of the ladle, a molten steel heating device that heats the molten steel in the ladle, and a degasser A ladle smelting furnace equipped with.
JP2006048705A 2006-02-24 2006-02-24 Ladle refining method and ladle refining furnace Expired - Fee Related JP4816138B2 (en)

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CN104673969A (en) * 2015-01-22 2015-06-03 河北钢铁股份有限公司承德分公司 Method and device for promoting slag liquid in half ladle to directionally flow

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JPH0633130A (en) * 1992-07-17 1994-02-08 Nippon Steel Corp Method for melting ultralow carbon steel
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JPS5887234A (en) * 1981-11-19 1983-05-25 Nippon Kokan Kk <Nkk> Refining method by vacuum melting
JPH02179813A (en) * 1988-12-28 1990-07-12 Nippon Steel Corp Method for refining molten metal into high purity and high cleanliness
JPH0565526A (en) * 1991-09-07 1993-03-19 Nippon Steel Corp Production of extremely low carbon steel
JPH0633130A (en) * 1992-07-17 1994-02-08 Nippon Steel Corp Method for melting ultralow carbon steel
JPH11124619A (en) * 1997-10-16 1999-05-11 Mitsui Eng & Shipbuild Co Ltd Device for electromagnetically stirring molten steel in ladle
JP2003213319A (en) * 2002-01-15 2003-07-30 Sumitomo Electric Ind Ltd Method for refining molten metal

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104673969A (en) * 2015-01-22 2015-06-03 河北钢铁股份有限公司承德分公司 Method and device for promoting slag liquid in half ladle to directionally flow

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