JP3771635B2 - Converter refining method - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、溶融金属反応容器、特に転炉の内張り耐火物の損耗を抑制するための転炉精錬方法に関するものである。
【０００２】
【従来の技術】
従来より転炉の内張り耐火物であるＭｇＯ−Ｃ質耐火物の損耗を抑制するための手段として、スラグコントロール技術およびスラグコーティング技術が実施されている。スラグコントロール技術とは、ＭｇＯ−Ｃ質耐火物の支配的な損耗要因がＭｇＯ−Ｃ質耐火物中のＭｇＯ粒子のスラグへの溶解であるとの観点に基づき確立されたものであり、具体的には吹錬前あるいは吹錬中にＭｇＯを、スラグに飽和する飽和ＭｇＯ量以上投入することで、ＭｇＯ−Ｃ質耐火物中のＭｇＯ粒子のスラグへの溶解を防止するものである（例えば、特開昭５４−５８１３号公報、「製銑・製鋼用耐火物」ｐ．３３０〜ｐ．３３５地人書館（株）平成７年６月２３日第１刷発行がある）。
【０００３】
一方、スラグコーティング技術としては、特開昭５３−３７１２０号公報、特公昭５９−３８２８２号公報で提案のように、出鋼後転炉炉内に残留したスラグに軽焼ドロマイト、生ドロマイトまたは石灰石等のスラグ固化剤を投入し、スラグの粘性を増加させた上で、転炉炉体の傾動やあるいは底吹羽口からのガス吹き込みによりスラグを内張り耐火物に付着させる方法、すなわちＭｇＯ−Ｃ質耐火物表面にコーティング層を形成させることで、耐火物中のＣの気相による酸化損耗の抑制や、発生熱応力の低減での熱応力破壊による剥離損耗の抑制を図るというものである。
【０００４】
【発明が解決しようとする課題】
しかしながら、吹錬前あるいは吹錬中にＭｇＯを多量に投入し、スラグ中のＭｇＯ濃度が飽和ＭｇＯ濃度超となるようにしても、内張り耐火物であるＭｇＯ−Ｃ質耐火物の損耗が増大する現象が多々発生した。
また、スラグ中のＭｇＯ濃度が飽和ＭｇＯ濃度超となるように吹錬前、あるいは吹錬中に投入するＭｇＯ量を調整して、吹錬を行い、出鋼後炉内に残留するスラグにスラグ固化剤を投入し、転炉炉体の傾動や、あるいは底吹羽口からのガス吹き込みを行うだけでは、十分なスラグコーティング性が得られないという現象も付随して発生した。
【０００５】
本発明は、吹錬中および／または吹錬開始前に装入するＭｇＯ量を調整して、スラグ中のＭｇＯ量およびＴ．Ｆｅ濃度を調節することで、転炉内張り耐火物の損耗を抑制するための転炉精錬方法を提供することを課題とするものである。
【０００６】
【課題を解決するための手段】
本発明は、上記課題を解決するためになされたものであり、その手段は、ＭｇＯ−Ｃ質耐火物で内張りされた上底吹き転炉内に吹錬中および／または吹錬前にＭｇＯ含有造滓材を投入し、スラグ中のＭｇＯ濃度を調整して内張り耐火物の損耗を防止する転炉精錬方法において、溶銑精錬終了後に生成する推定スラグ量が溶鋼１ｔ当たり６０ｋｇ以上になるように下記の生成スラグ量の式に基づき調整し、前記転炉吹錬中および／または転炉吹錬開始前に投入するＭｇＯ含有造滓材量を調整して、スラグ中のＭｇＯ量を飽和ＭｇＯの７０％以上１００％以下の範囲内で、かつスラグ中のＴ．Ｆｅ濃度を１６％以下にすることを特徴とする転炉精錬方法にある。
生成スラグ量（ｋｇ／ｔ）＝（生石灰投入量×生石灰中のＣａＯ含有率
＋石灰石投入量×石灰石中のＣａＯ含有率
＋軽焼ドロマイト投入量×軽焼ドロマイト
中のＣａＯ含有率＋生ドロマイト投入量×
生ドロマイト中のＣａＯ含有率）／（溶鋼
量×スラグ中のＣａＯ濃度）
【０００７】
【発明の実施の形態】
本発明者らは、前記課題で述べた現象の原因究明を行う過程で、スラグ中のＭｇＯ濃度が重要な役割を果たすのではないかと考えた。すなわち、スラグ中のＭｇＯ濃度が飽和ＭｇＯ濃度超では、スラグ中のＴ．Ｆｅ、つまり鉄酸化物濃度が増大するために、ＭｇＯ−Ｃ質耐火物中のＣと鉄酸化物との反応が促進することで、耐火物の損耗が進行すると共に、スラグ中のＴ．Ｆｅの増大によるスラグの融点の低下で、スラグの粘性が著しく低下するために、スラグコーティング性も低下するのではないかと推察して種々の試験検討を行った結果、図１〜図４に示す知見を得た。
【０００８】
図１はＭｇＯ−Ｃ質耐火物で内張りされた上底吹き転炉内での溶銑の精錬において、溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ以上である場合における溶銑精錬中に投入するＭｇＯ量の飽和ＭｇＯ量に対する比率と、内張り耐火物の損耗量との関係を示すものであり、この図から投入するＭｇＯ量を飽和ＭｇＯ量の７０％以上１００％以下の範囲にすることにより、精錬中に内張り耐火物からの損耗が防止されていることが判明した。
【０００９】
図２は、溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ未満の場合における溶銑精錬中に投入するＭｇＯ量の飽和ＭｇＯ量に対する比率と内張り耐火物の損耗量との関係を示すものであり、この図から投入するＭｇＯ量の如何に関わらず精錬中に内張り耐火物から損耗が生じていることが判明した。
ここで、損耗量とは、以下に定義されるものである。
【００１０】
損耗量（ｋｇ／ｔ）＝インプットＭｇＯ量（ｋｇ／ｔ）−アウトプットＭｇＯ量（ｋｇ／ｔ）
インプットＭｇＯ量（ｋｇ／ｔ）＝精錬中に投入する溶鋼１ｔ当たりのＭｇＯ量
アウトプットＭｇＯ量（ｋｇ／ｔ）＝溶鋼１ｔ当たりの生成スラグ量（ｋｇ／ｔ）×スラグ中のＭｇＯ濃度
損耗量が正値のときは吹錬中にＭｇＯ−Ｃ質耐火物は損耗しておらず、損耗量が負値のときは吹錬中にＭｇＯ−Ｃ質耐火物は損耗していることを意味する。
【００１１】
さらに、溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ以上である場合においては、図３から溶銑精錬中に投入するＭｇＯ量が飽和ＭｇＯ量の１００％以下の範囲に限り、スラグコーティング性にも優れることが判明した。また、溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ未満の場合においては、図４から溶銑精錬中に投入するＭｇＯ量の如何に関わらず、スラグコーティング性に劣ることが判明した。
【００１２】
なお、スラグコーティング性は、出鋼側、装入側、トラニオンの両側の４方向に対して、次に示すような目視判断による点数化表示を行った。
付着スラグにより煉瓦目地が全て覆われている ：３点
付着スラグにより煉瓦目地が半分覆われている ：２点
付着スラグにより煉瓦目地が全く覆われていない：１点
スラグコーティング性は、点数が高いほど優れていることを示す。
【００１３】
本発明に使用されるＭｇＯ含有造滓材とは、軽焼ドロマイト、生ドロマイトまたはマグネサイトのことであり、１種または２種以上を組み合わせて使用することが可能である。
【００１４】
本発明におけるスラグ中の飽和ＭｇＯ濃度は、スラグ中のＭｇＯ以外の成分と溶鋼温度から、熱力学的データを使用した平衡計算により求まるものである。
【００１５】
本発明における溶鋼１ｔ当たりの生成スラグ量は、例えば以下のように推定できるものである。
生成スラグ量（ｋｇ／ｔ）＝（生石灰投入量×生石灰中のＣａＯ含有率＋石灰石投入量×石灰石中のＣａＯ含有率＋軽焼ドロマイト投入量×軽焼ドロマイト中のＣａＯ含有率＋生ドロマイト投入量×生ドロマイト中のＣａＯ含有率）／（溶鋼量×スラグ中のＣａＯ濃度）
【００１６】
本発明における溶鋼１ｔ当たりの飽和ＭｇＯ量は、以下に定義されるものである。
飽和ＭｇＯ量（ｋｇ／ｔ）＝溶鋼１ｔ当たりの生成スラグ量×飽和ＭｇＯ濃度
【００１７】
溶銑精錬中に投入するＭｇＯ量が飽和ＭｇＯ量１００％以下では、スラグ中の鉄酸化物濃度が減少するので、鉄酸化物に侵食されるＭｇＯ−Ｃ質耐火物中のＣ量も低減されることになる。その結果、ＭｇＯ−Ｃ質耐火物の支配的な損耗機構は、スラグ中の鉄酸化物による炭素の侵食から、ＭｇＯ粒子のスラグへの溶解へ移行してくる。
【００１８】
ところで、ＭｇＯ−炭素質耐火物中の炭素は、スラグ中の鉄酸化物に侵食されるとＡｌ2 Ｏ3 −ＳｉＯ2 質の灰分を耐火物組織中に残存させる。そのＡｌ2 Ｏ3 −ＳｉＯ2 質灰分は、炭素に隣接するＭｇＯ粒子と反応し、ＭｇＯ粒子表面上にＭｇＯ−Ａｌ2 Ｏ3 −ＳｉＯ2 質の第２層を形成することになる。
この第２層の存在により、ＭｇＯ粒子はスラグと接触した場合にＭｇＯ粒子中のＭｇ2+の拡散が妨げられる結果、ＭｇＯ粒子のスラグへの溶解が進行せず、精錬中にＭｇＯ−Ｃ質耐火物からの損耗を防止することができる。
【００１９】
しかし、溶銑精錬中に投入するＭｇＯ量が飽和ＭｇＯ量７０％未満では、スラグ中の鉄酸化物によるＣの侵食が進行しないため、耐火物組織中にＡｌ2 Ｏ3 −ＳｉＯ2 質灰分が生成しなくなる。そのため、ＭｇＯ粒子面上への第２層の形成が不可能となり、ＭｇＯ粒子がスラグと接触した場合に、容易に溶解が進行する結果、精錬中にＭｇＯ−Ｃ質耐火物からの損耗が進行することになる。
【００２０】
スラグ中のＴ．Ｆｅ濃度を１６％以下とするのは、スラグコーティング性に優れるためである。スラグ中のＴ．Ｆｅ濃度が１６％超では、スラグの融点が低下しスラグの粘性が著しく低下するために、出鋼後に炉内に軽焼ドロマイト、生ドロマイトまたは石灰石等のスラグ固化剤を投入してもスラグの粘性が増加せず、転炉炉体の傾動やあるいは底吹羽口からのガス吹き込みを行ってもスラグが内張り耐火物に付着せず、スラグコーティング性に劣るからである。
【００２１】
一方、溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ未満である場合には、スラグ中の鉄酸化物濃度は、溶銑精錬中に投入するＭｇＯ量に依存せず著しく高くなる。その結果、ＭｇＯ−Ｃ質耐火物の支配的な損耗機構がスラグ中の鉄酸化物によるＣの侵食となるために、精錬中にＭｇＯ−Ｃ質耐火物の損耗が進行することになる。
【００２２】
【実施例】
以下に本発明の実施例を示す。
表１に使用した溶銑成分、精錬条件を示し、表２に試験条件を示した。両表共に実施例と比較例を示したが、表２には試験結果を併せて示した。
転炉は、上底吹きで容量は３４０ｔで、ＭｇＯ８０ｗｔ％、Ｃ２０ｗｔ％のＭｇＯ−Ｃ質耐火物で内張りしたものである。
【００２３】
【表１】
ＭｇＯ含有造滓材は、吹錬時間の２０％までの吹錬開始時に投入を行った。
表２中の投入ＭｇＯ量および投入ＭｇＯ比率とは、以下に定義されるものである。
投入ＭｇＯ量（ｋｇ／ｔ）＝（精錬中に使用したＭｇＯ量）／（溶鋼量）
投入ＭｇＯ比率（％） ＝（投入ＭｇＯ量×１００）／（飽和ＭｇＯ量）
スラグコーティングは、出鋼後炉内に残留させたスラグに生ドロマイト１ｔ、石灰石０．５ｔを投入し底吹羽口からのガス吹き込みによる方法で行った。
スラグコーティング性については、前記した評点方法と同様である。
【００２５】
【表２】
本実施例１〜５は、投入するＭｇＯ量はＭｇＯがスラグに飽和するＭｇＯ量未満であるにもかかわらず、精錬中にＭｇＯ−Ｃ質耐火物からの損耗が防止できていると共に、優れたスラグコーティング性を示した。
一方、比較例１は投入するＭｇＯ量が飽和ＭｇＯ量の７０％未満であるので、スラグコーティング性は優れるが、精錬中にＭｇＯ−Ｃ質耐火物は損耗している。比較例２は投入するＭｇＯ量が飽和ＭｇＯ量の９０％超であるので、精錬中にＭｇＯ−Ｃ質耐火物は損耗していると共に、スラグコーティング性に劣っていた。比較例３〜５は、生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ未満であるので、精錬中にＭｇＯ−Ｃ質耐火物は損耗していると共に、スラグコーティング性が劣っていた。
【００２７】
【発明の効果】
本発明により、本発明の転炉精錬方法は、ＭｇＯ−Ｃ質耐火物で内張りされた上底吹き転炉内で溶銑中にＭｇＯを投入し、スラグ中のＭｇＯ濃度を調整することで内張り耐火物の損耗を防止する転炉精錬方法において、投入するＭｇＯ量を飽和ＭｇＯ量の７０％以上１００％以下とすることで、吹錬中での内張り耐火物の損耗を防止し、さらにスラグ中のＴ．Ｆｅ濃度を１６％以下にすることによりスラグコーティング性を向上させることができ、その結果ＭｇＯ使用量の削減および転炉炉体寿命の延長による耐火物コストの削減が可能となる等の効果を奏するものである。
【図面の簡単な説明】
【図１】溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ以上の場合における飽和ＭｇＯ量に対する投入ＭｇＯ量比率と内張り耐火物の損耗量の関係を示した図
【図２】溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ未満の場合における飽和ＭｇＯ量に対する投入ＭｇＯ量比率と内張り耐火物の損耗量の関係を示した図
【図３】溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ以上の場合における飽和ＭｇＯ量に対する投入ＭｇＯ量比率とスラグコーティング性の関係を示した図
【図４】溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ未満の場合における飽和ＭｇＯ量に対する投入ＭｇＯ量比率とスラグコーティング性の関係を示した図
【図５】溶銑精錬終了後に生成するスラグ量が溶鋼１ｔ当たり６０ｋｇ以上の場合における飽和ＭｇＯ量に対する投入ＭｇＯ量比率とスラグ中のＴ．Ｆｅ濃度の関係を示した図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a converter refining method for suppressing wear of a molten metal reaction vessel, particularly a refractory lining the converter.
[0002]
[Prior art]
Conventionally, a slag control technique and a slag coating technique have been implemented as means for suppressing the wear of the MgO-C refractory that is the lining refractory of the converter. Slag control technology is established based on the viewpoint that the dominant wear factor of MgO-C refractories is dissolution of MgO particles in MgO-C refractories into slag. Is to prevent dissolution of MgO particles in the MgO-C refractory into the slag by adding more MgO than the saturated MgO amount saturated in the slag before or during blowing. JP-A-54-5813, “Refractories for iron making and steel making”, p. 330 to p. 335 Jishinshokan Co., Ltd., published on June 23, 1995).
[0003]
On the other hand, as slag coating technology, as proposed in JP-A-53-37120 and JP-B-59-38282, light-burned dolomite, raw dolomite or limestone is applied to slag remaining in the converter furnace after steelmaking. A method of adhering slag to the lining refractory by inclining the converter furnace body or blowing gas from the bottom blowing nozzle after increasing the viscosity of the slag by adding a slag solidifying agent such as MgO-C By forming a coating layer on the surface of the refractory refractory, it is intended to suppress oxidative wear due to the vapor phase of C in the refractory and to suppress peeling wear due to thermal stress breakdown by reducing the generated thermal stress.
[0004]
[Problems to be solved by the invention]
However, even if a large amount of MgO is added before or during blowing, and the MgO concentration in the slag exceeds the saturated MgO concentration, the wear of the MgO-C refractory that is the lining refractory increases. Many phenomena have occurred.
In addition, the amount of MgO introduced before or during blowing is adjusted so that the MgO concentration in the slag exceeds the saturated MgO concentration, and blowing is performed. There was also an accompanying phenomenon that sufficient slag coating could not be obtained simply by injecting a solidifying agent and tilting the converter furnace body or by blowing gas from the bottom blowing nozzle.
[0005]
The present invention adjusts the amount of MgO to be charged during blowing and / or before the start of blowing, An object of the present invention is to provide a converter refining method for suppressing the wear of the converter lining refractories by adjusting the Fe concentration.
[0006]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-mentioned problems, and its means is to contain MgO during and / or before blowing in an upper bottom blowing converter lined with MgO-C refractory. Zokasuzai was charged, in converter refining method for preventing wear of refractory lining by adjusting the MgO concentration in the slag, below as estimation slag formed after hot metal refining completion becomes more 60kg per molten steel 1t And adjusting the amount of MgO-containing steelmaking material introduced during the converter blowing and / or before the start of the converter blowing, to adjust the amount of MgO in the slag to 70% of saturated MgO. % In the range of not less than 100% and not more than 100%, and T. In the converter refining method, the Fe concentration is 16% or less.
Amount of generated slag (kg / t) = (input amount of quick lime × CaO content in quick lime)
+ Limestone input x CaO content in limestone
+ Light-burning dolomite input x Light-burning dolomite
CaO content in raw material + raw dolomite input x
CaO content in raw dolomite) / (molten steel
Amount x CaO concentration in slag)
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors thought that the MgO concentration in the slag might play an important role in the process of investigating the cause of the phenomenon described in the above problem. That is, when the MgO concentration in the slag exceeds the saturated MgO concentration, the T.I. Since the concentration of Fe, that is, iron oxide increases, the reaction between C and iron oxide in the MgO-C refractory promotes, so that wear of the refractory progresses and T. As the melting point of the slag decreases due to the increase in Fe, the viscosity of the slag is significantly reduced, so that the slag coating properties are also considered to be reduced. Obtained knowledge.
[0008]
FIG. 1 shows that in the refining of hot metal in an upper bottom blown converter lined with MgO-C refractories, the amount of slag generated after the hot metal refining is 60 kg or more per 1 ton of molten steel and is introduced during hot metal refining. The relationship between the ratio of the amount of MgO to the amount of saturated MgO and the amount of wear of the lining refractory is shown. By making the amount of MgO input from this figure 70% or more and 100% or less of the amount of saturated MgO, It was found that wear from the lining refractory was prevented during refining.
[0009]
FIG. 2 shows the relationship between the ratio of the amount of MgO charged during hot metal refining to the amount of saturated MgO and the amount of wear of the lining refractory when the amount of slag generated after hot metal refining is less than 60 kg per ton of molten steel. From this figure, it was found that the lining refractory was worn during refining regardless of the amount of MgO added.
Here, the amount of wear is defined as follows.
[0010]
Amount of wear (kg / t) = input MgO amount (kg / t) −output MgO amount (kg / t)
Input MgO amount (kg / t) = MgO amount per 1 ton of molten steel input during refining Output MgO amount (kg / t) = Amount of generated slag per 1 t of molten steel (kg / t) × Amount of MgO concentration wear in slag When the value is positive, the MgO-C refractory is not worn during blowing, and when the amount of wear is negative, it means that the MgO-C refractory is worn during blowing. .
[0011]
Furthermore, in the case where the amount of slag generated after the hot metal refining is 60 kg or more per 1 ton of molten steel, the slag coating property is limited as long as the amount of MgO charged during hot metal refining is within 100% or less of the saturated MgO amount from FIG. Also proved to be excellent. Further, when the amount of slag generated after hot metal refining is less than 60 kg per ton of molten steel, it was found from FIG. 4 that the slag coating property is inferior regardless of the amount of MgO introduced during hot metal refining.
[0012]
In addition, the slag coating property was scored by visual judgment as shown below for the four directions on both the steel output side, the charging side and the trunnion.
Adhesive slag covers all brick joints: 3 point adhering slag covers half brick joints: 2 adhering slag does not cover brick joints at all: 1 point slag coating performance is high It shows that it is excellent.
[0013]
The MgO-containing ironmaking material used in the present invention is light-burned dolomite, raw dolomite, or magnesite, and can be used alone or in combination of two or more.
[0014]
The saturated MgO concentration in the slag in the present invention is determined by equilibrium calculation using thermodynamic data from components other than MgO in the slag and the molten steel temperature.
[0015]
The amount of generated slag per 1 t of molten steel in the present invention can be estimated as follows, for example.
Amount of generated slag (kg / t) = (input amount of quick lime × CaO content rate in quick lime + input amount of limestone × CaO content rate in limestone + input amount of light-burned dolomite × CaO content rate in light-burned dolomite + raw dolomite input Amount × CaO content in raw dolomite) / (molten steel × CaO concentration in slag)
[0016]
The saturated MgO amount per ton of molten steel in the present invention is defined as follows.
Saturated MgO amount (kg / t) = produced slag amount per ton of molten steel × saturated MgO concentration
When the amount of MgO charged during hot metal refining is less than 100% of saturated MgO, the concentration of iron oxide in the slag decreases, so the amount of C in the MgO-C refractory eroded by iron oxide is also reduced. It will be. As a result, the dominant wear mechanism of MgO-C refractories shifts from carbon erosion by iron oxide in slag to dissolution of MgO particles in slag.
[0018]
By the way, when the carbon in the MgO-carbonaceous refractory is eroded by the iron oxide in the slag, the ash content of Al 2 O 3 —SiO 2 remains in the refractory structure. The Al 2 O 3 —SiO 2 ash reacts with MgO particles adjacent to the carbon to form a second layer of MgO—Al 2 O 3 —SiO 2 on the surface of the MgO particles.
Due to the presence of this second layer, when MgO particles come into contact with the slag, the diffusion of Mg 2+ in the MgO particles is hindered. As a result, the dissolution of the MgO particles into the slag does not proceed, and the MgO-C material during refining. Wear from the refractory can be prevented.
[0019]
However, if the amount of MgO input during hot metal refining is less than 70% of the saturated MgO amount, the erosion of C by iron oxide in the slag does not proceed, so that Al 2 O 3 —SiO 2 ash is generated in the refractory structure. No longer. Therefore, it becomes impossible to form the second layer on the surface of the MgO particles, and when the MgO particles come into contact with the slag, the dissolution proceeds easily. As a result, wear from the MgO-C refractory progresses during refining. Will do.
[0020]
T. in slag The reason why the Fe concentration is 16% or less is that the slag coating property is excellent. T. in slag When the Fe concentration exceeds 16%, the melting point of the slag is lowered and the viscosity of the slag is remarkably lowered. Therefore, even if a light-burning dolomite, raw dolomite, or limestone is added to the furnace after steelmaking, This is because the viscosity does not increase and the slag does not adhere to the lining refractory even if the converter furnace body is tilted or the gas is blown from the bottom blowing port, and the slag coating property is poor.
[0021]
On the other hand, when the amount of slag produced after the hot metal refining is less than 60 kg per 1 ton of molten steel, the iron oxide concentration in the slag becomes extremely high regardless of the amount of MgO introduced during hot metal refining. As a result, the dominant wear mechanism of the MgO-C refractory is C erosion by the iron oxide in the slag, so that the wear of the MgO-C refractory proceeds during refining.
[0022]
【Example】
Examples of the present invention are shown below.
Table 1 shows the hot metal components and refining conditions used, and Table 2 shows the test conditions. In both tables, Examples and Comparative Examples are shown, but Table 2 also shows the test results.
The converter is blown from the top, has a capacity of 340 t, and is lined with MgO—C refractory with
[0023]
[Table 1]
The MgO-containing ironmaking material was charged at the start of blowing until 20% of the blowing time.
The input MgO amount and the input MgO ratio in Table 2 are defined below.
Input MgO amount (kg / t) = (MgO amount used during refining) / (Amount of molten steel)
Input MgO ratio (%) = (input MgO amount × 100) / (saturated MgO amount)
The slag coating was performed by a method in which raw dolomite 1t and limestone 0.5t were added to slag remaining in the furnace after steel output, and gas was blown from the bottom tuyeres.
About slag coating property, it is the same as that of the above-mentioned scoring method.
[0025]
[Table 2]
In Examples 1 to 5, although the amount of MgO to be added is less than the amount of MgO saturated with slag, wear from the MgO-C refractory can be prevented during refining and excellent. Slag coating was shown.
On the other hand, in Comparative Example 1, since the amount of MgO input is less than 70% of the amount of saturated MgO, the slag coating property is excellent, but the MgO-C refractory is worn during refining. In Comparative Example 2, since the amount of MgO to be added was more than 90% of the amount of saturated MgO, the MgO-C refractory was worn during refining and the slag coating property was inferior. In Comparative Examples 3 to 5, since the amount of slag produced was less than 60 kg per ton of molten steel, the MgO-C refractory was worn during refining and the slag coating property was inferior.
[0027]
【The invention's effect】
According to the present invention, the converter refining method of the present invention is a refractory lining by pouring MgO into hot metal in an upper-bottom blowing converter lined with MgO-C refractories and adjusting the MgO concentration in the slag. In the converter refining method for preventing wear of materials, the amount of MgO to be added is set to 70% or more and 100% or less of the saturated MgO amount to prevent wear of the lining refractory during blowing, and further in the slag T.A. By making the
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the ratio of the amount of MgO added to the amount of saturated MgO and the amount of wear of the refractory lining when the amount of slag generated after hot metal refining is 60 kg or more per 1 ton of molten steel. Fig. 3 shows the relationship between the ratio of the MgO content to the amount of saturated MgO and the amount of wear of the refractory lining when the amount of slag to be produced is less than 60 kg per 1 ton of molten steel. FIG. 4 is a graph showing the relationship between the ratio of the charged MgO amount to the saturated MgO amount and the slag coating property in the case of 60 kg or more. FIG. 4 shows the input MgO relative to the saturated MgO amount when the amount of slag generated after hot metal refining is less than 60 kg per 1 ton of molten steel. Fig. 5 shows the relationship between the amount ratio and slag coating properties. Fig. 5 shows the amount of slag produced after hot metal refining. T. of input MgO weight ratio and the slag versus a saturated MgO amount in the case of more than 60kg per steel 1t Diagram showing the relationship of Fe concentration
Claims (1)
生成スラグ量（ｋｇ／ｔ）＝（生石灰投入量×生石灰中のＣａＯ含有率
＋石灰石投入量×石灰石中のＣａＯ含有率
＋軽焼ドロマイト投入量×軽焼ドロマイト
中のＣａＯ含有率＋生ドロマイト投入量×
生ドロマイト中のＣａＯ含有率）／（溶鋼
量×スラグ中のＣａＯ濃度）Wearing of MgO-containing ironmaking material during blowing and / or before blowing into the top-bottom blowing converter lined with MgO-C refractory, and adjusting the MgO concentration in the slag to wear out the lining refractory In the converter refining method, the estimated slag amount generated after the hot metal refining is adjusted based on the following generated slag amount formula so that the estimated amount of slag is 60 kg or more per ton of molten steel, and during the converter blowing and / or The amount of MgO-containing steelmaking material introduced before the start of furnace blowing is adjusted so that the amount of MgO in the slag is within the range of 70% to 100% of saturated MgO, and the T.O. A converter refining method, wherein the Fe concentration is 16% or less.
Amount of generated slag (kg / t) = (input amount of quick lime × CaO content in quick lime)
+ Limestone input x CaO content in limestone
+ Light-burning dolomite input x Light-burning dolomite
CaO content in raw material + raw dolomite input x
CaO content in raw dolomite) / (molten steel
Amount x CaO concentration in slag)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18993696A JP3771635B2 (en) | 1996-07-02 | 1996-07-02 | Converter refining method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18993696A JP3771635B2 (en) | 1996-07-02 | 1996-07-02 | Converter refining method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1017915A JPH1017915A (en) | 1998-01-20 |
| JP3771635B2 true JP3771635B2 (en) | 2006-04-26 |
Family
ID=16249695
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18993696A Expired - Fee Related JP3771635B2 (en) | 1996-07-02 | 1996-07-02 | Converter refining method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3771635B2 (en) |
Families Citing this family (2)
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|---|---|---|---|---|
| JP5552846B2 (en) * | 2010-03-09 | 2014-07-16 | 新日鐵住金株式会社 | Converter refractory protection method for converter |
| KR101739277B1 (en) * | 2015-12-11 | 2017-05-25 | 주식회사 포스코 | Method for refining stainless steel in converter with decreasing corrosion of refractory in converter |
-
1996
- 1996-07-02 JP JP18993696A patent/JP3771635B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1017915A (en) | 1998-01-20 |
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