JP3793473B2

JP3793473B2 - Operation method of a converter equipped with a hot metal storage furnace

Info

Publication number: JP3793473B2
Application number: JP2002067346A
Authority: JP
Inventors: 直樹平嶋
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2002-03-12
Filing date: 2002-03-12
Publication date: 2006-07-05
Anticipated expiration: 2022-03-12
Also published as: JP2003268433A

Description

【０００１】
【発明の属する技術分野】
本発明は、転炉に使用する溶銑の成分を均一にすると同時に、溶銑の温度、炭素濃度を調整して転炉の溶銑比のバラツキを小さくする溶銑の加熱式貯銑炉を備えた転炉の操業方法に関する。
【０００２】
【従来の技術】
従来、転炉内に屑鉄や酸化鉄等の冷材を装入しその後、高炉から出銑した溶銑を溶銑鍋やトピードカー（混銑車）等に一旦受けて搬送し、そのままの状態、あるいは脱硫や脱燐処理等の予備処理を施した後、転炉用の溶銑鍋に移し、クレーン等で搬送して転炉内に装入する。そして、上吹きランスから酸素を吹きつけて脱炭精錬を行うことにより溶鋼が製造される。この転炉の脱炭精錬では、吹錬を終了する吹き止め時の温度及び炭素濃度が目標値になるように、過去の吹酸実績等を参照しながら溶銑量や屑鉄、酸化鉄等の配合量を決定している。
【０００３】
しかし、溶銑の成分や温度が変動するため、その都度、転炉の溶銑量や屑鉄、酸化鉄等の配合量を変更して脱炭精錬を行っているが、吹き止めの温度及び炭素濃度の実績が変動し、温度及び炭素濃度が目標値を外れると、温度や炭素濃度を合わせるという過剰な吹酸（再吹錬）による脱炭精錬や二次精錬にてＡｌ合金を添加する昇熱を余儀なくされている。この対策として、実開昭６２−１７５０５８号公報に記載されているように、混銑炉（貯銑炉）の出銑口を指向した加熱バーナーを配置し、混銑炉に装入した溶銑を加熱することにより、放熱を抑制してスラグが固化するのを防止して安定した出銑を行うことが提案されている。
【０００４】
更に、特開平１−１２３０１４号公報に記載されているように、高炉の溶銑を貯銑炉に受け、この溶銑に対して必要に応じた脱珪や脱燐、脱硫処理等の予備処理を施すと共に、炭素含有量を低減してから転炉に装入する。この方法は、計画的に予備処理を行い、この溶銑を用いて脱炭精錬を行うことにより、過剰な予備処理を回避し、予備処理に使用するフラックス（処理剤）の無駄を無くし、しかも、転炉における熱補償用の炭材の使用量の節減を図ることが提案されている。また、特開平１１−２４８３６８号公報に記載されているように、溝型誘導加熱装置と水分を乾燥除去した屑鉄を投入する装置を配置した貯銑炉が既に周知であり、この貯銑炉を利用して、溶銑を介して溶解することによって、溶融鉄源を多く製造して転炉に供給することにより、転炉の生産性や操業を安定して行うことも可能である。
【０００５】
【発明が解決しようとする課題】
しかしながら、実開昭６２−１７５０５８号公報に記載された貯銑炉を用いた場合、貯銑炉内の溶銑の全体を加熱することが困難であり、溶銑の成分や温度が必ずしも一定にできず、転炉に配合する溶銑比を所定の範囲に調整することができない。その結果、その都度、転炉の溶銑量や屑鉄、酸化鉄等の配合量が変動し、吹き止めの温度及び炭素濃度の目標値外れが発生し、過剰な吹酸（再吹錬）による脱炭精錬となる。そして、溶鋼の精錬歩留りの低下や過剰な吹酸による酸素原単位の増加、溶鋼の生産性の低下、品質の悪化等を生じる。
【０００６】
更に、特開平１−１２３０１４号公報に記載された方法においても、過剰な溶銑の脱珪や脱燐、脱硫処理等の予備処理を行うことを回避できるが、貯銑中の放熱による温度降下や前記した予備処理による温度降下、及び溶銑鉄中の炭素濃度の低下等を招くことになる。この溶銑を転炉に装入して吹酸する場合、転炉での溶銑の配合比をその時の温度や炭素濃度によって変える必要がある。特に、温度の場合においては、溶銑の温度が低いと転炉での溶銑の配合比を高める必要があり、溶銑の温度が高くなると転炉での溶銑の配合比を低くする必要があるので、その都度、転炉に配合する溶銑比が変化し、吹酸による脱炭精錬の終点である吹き止め時の温度及び炭素濃度にバラツキが発生する。
【０００７】
また、特開平１１−２４８３６８号公報に記載された方法では、溝型誘導加熱装置を備えているため、水分を乾燥除去した屑鉄を溶解し、溶銑の量を多くして転炉に供給することが可能になるが、転炉での安定した吹酸脱炭精錬に重要な溶銑の配合比を一定にするいわゆる転炉での入熱量を一定にすることについて何ら開示されておらず、この溶銑を使用した際、前記した実開昭６２−１７５０５８号公報及び特開平１−１２３０１４号公報と同様のその都度、転炉の溶銑比が変化し、吹酸による脱炭精錬の終点である吹き止め時の温度及び炭素濃度にバラツキを招くと言う問題が生じる。
【０００８】
本発明はかかる事情に鑑みてなされたもので、転炉で配合する溶銑比のバラツキを小さくして吹酸による脱炭精錬の吹き止め時の溶鋼の温度及び炭素濃度の的中率を高め、溶鋼の歩留り低下や酸素原単位の節減と溶鋼の生産性を向上し、精錬コストを低減することができる溶銑の加熱式貯銑炉を備えた転炉の操業方法を提供することを目的とする。
【０００９】
【課題を解決するための手段】
前記目的に沿う本発明に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法は、高炉から出銑した溶銑、あるいは該溶銑に予備処理を施した後に加熱手段を備えた貯銑炉に装入し、該貯銑炉内の溶銑を加熱して昇熱を行い、前記貯銑炉内の溶銑温度を次工程の転炉精錬時の溶銑配合比の変動代が少なくとも３％以内になるように調整する。この方法により、高炉から出銑した溶銑、あるいは溶銑に予備処理を施した後の溶銑を貯銑炉に装入し、この溶銑を誘導加熱装置により加熱して転炉に配合する溶銑比、あるいは入熱の差が３％以内になるように溶銑温度を調整しているので、吹酸による脱炭精錬の終点である吹き止め温度及び炭素濃度を目標値に的中させることができ、転炉の安定した脱炭精錬が可能になる。
ここで、転炉の溶銑比の変動代が３％を超えると、転炉の入熱の変動に加え、転炉の炉体顕熱や炉内形状等の外乱要因が顕在化し、吹き止め温度や炭素濃度の的中率が急激に低下し、再吹酸が増加する。
【００１０】
本発明に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法において、前記加熱手段は誘導加熱を用い、冷材を溶解すると良い。これにより、貯銑炉内の溶銑の全体を加熱することができ、しかも、溶銑に対し、直接に電気抵抗熱を付与するので加熱効率を高めることができる。また、貯銑炉内の溶銑の温度の調整を容易に行うと共に、冷材を溶解して溶銑を増産し、転炉に配合する溶銑比、あるいは入熱の必要量に応じた配合を行うことができる。
【００１１】
更に、本発明に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法において、前記次工程の転炉精錬時の溶銑配合比は鋼種ごとの配合比にすることが好ましい。これにより、鋼種ごとの転炉の溶銑比、あるいは入熱に対応した吹酸脱炭精錬を行うことが可能となり、次チャージの配合条件である溶銑比、あるいは入熱を的確に予測でき、経過時間による外乱要因を解消することができる。そして、吹き止め温度及び炭素濃度を目標値により的中させることができる。
また、本発明に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法において、前記溶銑鉄の加熱に夜間の電力を用いることも可能である。これにより、昇熱に用いる電力コストを低減することができ、しかも、冷材等を多量に溶解することができ、転炉に配合する溶銑量を増量して高溶銑比の操業を行うことができる。そして、高溶銑比による脱炭精錬を安定して行うことができる。
【００１２】
更に、前記目的に沿う溶銑の加熱式貯銑炉を備えた転炉の操業方法において、高炉から出銑した溶銑、あるいは該溶銑に予備処理を施した後に加熱手段を備えた貯銑炉に装入して該貯銑炉内に冷材を溶解するに当たり、前記貯銑炉内の溶銑のトランプエレメント成分を測定し、該溶銑のトランプエレメント値に応じて次工程の転炉精錬時の配合条件を調整することもできる。この方法により、貯銑炉内に冷材を添加して加熱手段により溶解した後、その溶銑のトランプエレメント成分を把握することができる。この値に応じて転炉に配合する屑鉄の種類と量を決定することができるので、転炉で使用する屑鉄をトランプエレメント成分の許容範囲で、低級屑鉄を増量使用やトランプエレメント成分を考慮した低級屑鉄の適正使用を可能にすることができる。
【００１３】
また、溶銑の加熱式貯銑炉を備えた転炉の操業方法において、前記冷材は屑鉄、あるいはダスト、スラジのいずれか１種以上を添加すると良い。これにより、融点の高い屑鉄やダスト等を浸炭に伴う溶融温度低下現象（浸炭作用）を利用して容易に溶解することができ、この溶解に必要な熱の付与が行い易くなり、添加する冷材量を多くすることができる。更に、低級屑鉄に含まれる蒸発性の高い不純物を除去することができるので、亜鉛、錫等の不純物の成分を少なくすることができる。
【００１４】
【発明の実施の形態】
続いて、添付した図面を参照しつつ、本発明を具体化した実施の形態につき説明し、本発明の理解に供する。
図１は、本発明の一実施の形態に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法に適用される加熱式貯銑炉の全体図、図２は、同加熱式貯銑炉のＡ−Ａ矢視断面図、図３は、溶銑配合比の頻度、図４は、脱炭精錬の吹き止め的中率の比較、図５は、転炉での低級屑鉄配合量の比較を表す図である。
【００１５】
図１〜図２に示すように、本発明の一実施の形態に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法に用いられる加熱式貯銑炉１は、円筒状の鉄皮２に図示しない耐火物を内張りした回動可能な貯銑炉４と、この貯銑炉４の円筒体の胴体の両側にそれそれ配置した加熱装置の一例である溝型誘導加熱装置３をそれぞれを設けている。更に、貯銑炉４の円筒体の上方には、クレーン等の搬送手段により溶銑を炉内に装入するための開閉蓋９を設けた受銑口５と、冷材の一例である屑鉄を装入するための図示しない開閉蓋を設けた装入口６を設け、内部の溶銑８を溶銑鍋等に出銑するための出銑口７とを備えている。
【００１６】
次に、加熱式貯銑炉を用い本実施の形態に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法について説明する。
高炉から出銑した溶銑をトピードカーで搬送し、脱珪、脱燐、脱硫等の予備処理を施してから溶銑鍋に入れ、クレーンで吊り上げて貯銑炉４の開閉蓋９を開き、受銑口５から炉内に溶銑を装入する。この溶銑の装入を繰返して炉内に１０００トンの溶銑８を貯銑した。そして、溶銑８をサンプリングし、温度及び炭素濃度を測定し、温度が１２７０℃と低かったので、溝型誘導加熱装置３のそれぞれに通電し、３．５ＭＷの出力で加熱を開始した。出力を順次上げ、誘導加熱により、溶銑８の温度が１３４０℃に昇熱できたので、市中の回収屑である低級屑鉄を１．０トン／分の速度で連続して添加し、通電状態を継続して屑鉄を溶解した。この屑鉄の溶解により、溶銑８の炭素濃度が低下するので、溶銑８の炭素濃度が４．０質量％を切った時点で、新しい溶銑を貯銑炉４の開閉蓋９を開いて受銑口５から炉内に装入し、屑鉄の添加と新しい溶銑の装入を繰返し行った。その結果、溶銑の温度を１３４０℃、炭素濃度を４．０質量％の溶銑８を１４８０トン製造できた。この貯銑炉４内の溶銑８のトランプエレメント成分は、代表的なものとして例えば、銅（Ｃｕ）０．００８質量％、錫（Ｓｎ）０．００１質量％、クロム（Ｃｒ）０．０５質量％であった。
【００１７】
次に、転炉の脱炭精錬を行う当該チャージは、一般の炭素濃度が０．１０質量％以下の低炭素溶鋼であるため、過去の吹酸による脱炭精錬の条件とその吹き止め実績を参照して当該チャージに最も類似したものを選定し、この条件の溶銑比９１．０％となるように、溶銑８を３４３トン溶銑鍋に出銑してクレーンを用いて転炉に装入した。その後、３４．０トンの屑鉄を転炉に装入した。そして、生石灰や鉄鉱石等の副原料を添加し、上吹きランスからの吹酸量、上吹きランス高さ等の他の吹酸条件を同一にして脱炭精錬を行った。その結果、脱炭精錬の終点である吹き止めの溶鋼の温度を１６８５℃、炭素濃度を０．０７質量％にでき、目標値である温度１６７５〜１６９０℃、炭素濃度０．０４〜０．０６質量％の範囲に的中させることができた。転炉を用いた脱炭精錬は、炭素濃度が０．１０超、０．３０質量％未満の中炭素溶鋼、炭素濃度が０．３０超、０．８０質量％の高炭素溶鋼の精錬も含め鋼種ごとに行ったが、いずれも目標の温度、炭素濃度に的中させることができ、温度外れや炭素濃度の高めによる再吹錬が無く、炭素濃度の低過ぎによる出鋼時の加炭材の添加も少なくできた。
【００１８】
図３に低炭素溶鋼の転炉の脱炭精錬を行う場合の転炉の溶銑配合比（溶銑比）を貯銑炉４の溝型誘導加熱装置３のそれぞれに通電して屑鉄の溶解と新しい溶銑を入れて昇熱し、溶銑８の温度及び炭素濃度を一定にして配合した本発明の場合と、溶銑の温度及び炭素濃度を調整しない従来の溶銑配合比の状態を示すが、本発明の場合、転炉の溶銑配合比が８９〜９２％で、バラツキを３％以下にすることができ、転炉の溶銑温度、炭素濃度から決まる入熱量も３％以下狭い範囲に安定して調整することができた。その結果、図４に示すように、転炉の脱炭精錬の吹き止め時の温度、炭素濃度の目標値に対する的中率を９８％以上にでき、再吹酸の発生率を２．０％以下にすることができた。
【００１９】
一方、従来の溶銑温度及び炭素濃度を調整しない場合の溶銑配合比は、８６〜９３．５％の範囲となり、黒鉛やコークス、石炭等の炭材の添加が必要となり、炭材の添加による溶鋼中の硫黄（Ｓ）濃度の上昇が生じた。しかも、上吹きランスからの吹酸量、上吹きランス高さ等の他の条件を同一にして脱炭精錬を行ったにも係わらず、転炉の脱炭精錬の吹き止め時の温度、炭素濃度の目標値に対する的中率を８９％となり、再吹酸の発生率も９．０％に増加し、再吹酸による溶鋼歩留りの低下や酸素原単位の増加、溶鋼の生産性の低下等が生じた。
【００２０】
溶銑８の温度を溝型誘導加熱装置３の各々によって高め、炭素濃度を一定の範囲になるように貯銑炉１を用いて調整することに加え、同時に、屑鉄等を溶解して溶銑８を増産するので、前工程である高炉の操業の変動に起因する溶銑不足の影響を回避することができる。更に、後工程である連続鋳造設備とのマッチングが良好になり、転炉操業と鋳造操業のスケジュールを効率良く運用でき、製鋼工程全体の生産性や総合コストの低減を十分に発現することができる。そして、転炉及び連続鋳造設備の安定した操業により、溶鋼及び鋳片の品質や生産性を向上することができる。更に、電気抵抗熱を用いて直に溶銑８を加熱するので、加熱の熱効率が８０％以上と高く維持でき、しかも、使用電力費の安い夜間電力を積極的に活用した低コストの加熱を行うことができる。
【００２１】
また、貯銑炉４内に屑鉄を添加して浸炭作用を活用して速やかに溶解し、溶銑８の成分を均一にしているため、屑鉄の溶解後の溶銑８をサンプリングして分析することにより、転炉に配合する溶銑８のトランプエレメント成分であるＣｕやＳｎ、Ｃｒ等を事前に把握することができる。従って、転炉において、溶銑８の配合量を決定した時点で、一般に規定された鋼材のトランプエレメントの規格値から、トランプエレメント成分の各元素ごとの許容値が容易に求められる。
【００２２】
図５は、転炉での屑鉄の全配合量に対する低級屑の配合量割合を示すが、貯銑炉４内で屑鉄を予め溶解した場合、屑鉄の溶解した量を加え３０％の低級屑を使用することができ、トランプエレメント成分を鋼材の規格値よりも低い値である例えば、銅（Ｃｕ）０．００８質量％、錫（Ｓｎ）０．００１質量％、クロム（Ｃｒ）０．０５質量％に維持することができた。一方、予め低級屑を溶解しない従来の場合、低級屑のトランプエレメント成分のバラツキを考慮した配合にせざるを得ないため、使用する低級屑が１０％の低い配合量となった。そして、トランプエレメント成分を鋼材の規格値外れを抑制できたが、安価な低級屑鉄の使用量が少なくなった分だけ溶鋼の溶製コストが高くなった。また、本実施の形態では、冷材として屑鉄を用いて説明したが、転炉から発生するダストを塊状に成形したものや集塵スラジを乾燥して成形したものを使用することができる。
【００２３】
【実施例】
次に、溶銑の加熱式貯銑炉を備えた転炉の操業方法の実施例について説明する。高炉から出銑した溶銑を脱珪、脱燐、脱硫の予備処理を施した。この溶銑をそのままトピードカーで搬送して溶銑鍋を介して貯銑炉に１２７０℃の溶銑を５００トン装入し、溝型誘導加熱装置に通電して１０ＭＷの出力で１３４０℃になるまで加熱し、温度が１２７０℃の溶銑の装入と溝型誘導加熱装置による加熱を繰返し、１３４０℃の溶銑を１０００トン蓄えた。そして、１３４０℃の溶銑に屑鉄を市中の回収屑である低級屑鉄を１．０トン／分の速度で連続して添加し、通電状態を継続しながら屑鉄を溶解し、炭素濃度が４．０質量％を維持できるように、この屑鉄の溶解とトピードカーで搬送される新しい溶銑の装入を繰返し行い、１４８０トンの溶銑を製造した。この溶銑を転炉の溶銑比のバラツキが３％以内になるように配合して高溶銑比操業を行った。
【００２４】
実施例１は、炭素濃度が０．１０％以下の低炭素溶鋼を溶製するため、溶銑の温度１３４０℃とし、転炉の溶銑比を９１．０％、残部の９．０％を低級屑鉄とした配合にし、炭素濃度が０．１０％以下の低炭素溶鋼の過去の吹酸条件である送酸量、ランス高さ等を同一の吹酸条件にして脱炭精錬を行った。その結果、脱炭精錬の終点である吹き止めの温度を１６８０℃、炭素濃度を０．０５％の目標値に的中させることができた。
【００２５】
実施例２は、炭素濃度が０．１０％以下の低炭素溶鋼を溶製するため、転炉の溶銑比を９０〜９２％になるように、溝型誘導加熱装置の出力を調整して溶銑の温度１３４０〜１３７０℃とし、転炉の溶銑以外の残部を低級屑鉄とした配合にして、炭素濃度が０．１０％以下の低炭素溶鋼の過去の吹酸条件である送酸量、ランス高さ等を同一の吹酸条件にして１０チャージの脱炭精錬を行った。そして、脱炭精錬の終点である吹き止めの温度及び炭素濃度の目標値に対する的中率と再吹酸の発生率を調査した。その結果、吹き止めの温度及び炭素濃度の目標値に対する的中率を９８％にでき、再吹酸率がわずか２％にすることができた。吹酸による脱炭精錬が安定しているので、溶鋼の溶製歩留りが良好であり、精錬時間も大幅に短縮して生産性が向上した。
【００２６】
実施例３は、炭素濃度が０．１０％以下の低炭素溶鋼を溶製するため、温度１３４０℃の溶銑を用いて転炉の溶銑比を９０．４％にし、この時の溶銑のトランプエレメント成分を分析し、代表的なものとしてＣｕ、Ｃｒ、Ｓｎ、Ｐｂの値を把握し、全屑鉄９．６％の配合量の内、低級屑鉄を３０％（残り７０％はクロップ等の良質屑鉄）にした配合とし、吹酸による脱炭精錬を行った。その結果、脱炭精錬の終点である吹き止め温度を１６９０℃、炭素濃度を０．０９％の目標値に的中することができた。しかも、トランプエレメント成分を鋼材規格であるＣｕ０．１０質量％以下、Ｃｒ０．１０質量％以下、Ｓｎ０．０２質量％以下、Ｐｂ０．０２質量％以下にすることができた。そして、転炉に配合する低級屑鉄の全使用量を増加することができ、溶鋼のトランプエレメント成分外れを確実に防止することができた。
【００２７】
なお、中炭素溶鋼及び高炭素溶鋼についても、転炉の溶銑比が３％以内になるように、溝型誘導加熱装置により、屑鉄の溶解と溶銑の温度、炭素濃度の調整を行い、過去の同一鋼種の吹酸条件にして脱炭精錬を行ったが、いずれも目標値に対する的中率を９８％以上にでき、再吹酸率がわずか２％未満にすることができ、前記実施例と同様の効果が得られた。また、予め溶銑のトランプエレメント成分測定してから、トランプエレメントの鋼材規格以下となるように屑鉄の種類の選択と配合量にしたので、溶鋼のトランプエレメント成分外れは無かった。
【００２８】
これに対し、溶銑の温度及び炭素濃度の調整を行わないで、炭素濃度が０．１０％以下の低炭素溶鋼を溶製したが、転炉の溶銑比が８６〜９３．５％と大きく変動し、吹酸による脱炭精錬の吹き止めの温度及び炭素濃度が目標値から外れ、的中率が８９％に大幅に低下し、炭材の添加による溶鋼中の硫黄（Ｓ）濃度の上昇、再吹酸による溶鋼歩留りの低下や酸素原単位の増加、溶鋼の生産性の低下等が生じた。更に、溶銑比が変動するのに伴い、屑鉄配合比も変動し、トランプエレメントのバラツキの大きい屑鉄を配合するため、転炉で溶製した溶鋼のトランプエレメントがバラツキを招くので、良質屑鉄の配合量を増加する操業になる。そして、良質屑鉄の配合量の増加に伴い安価な低級屑鉄の使用量が減少した。
【００２９】
以上、本発明の実施の形態を説明したが、本発明は、上記した形態に限定されるものでなく、要旨を逸脱しない条件の変更等は全て本発明の適用範囲である。例えば、冷材として屑鉄やダスト、スラジの他に、型銑等の炭素含量の多い鉄源を使用して誘導加熱装置により溶解することができる。更に、脱炭精錬炉としても、転炉の他に、上底吹き転炉や電気炉等に供給する溶銑を加熱して温度及び炭素濃度の調整、トランプエレメント成分の調整や予測配合して適用することができ、供給する溶銑そのものを増産することができる。また、転炉での溶銑比の調整は、溶銑の温度が１０℃変動すれば溶銑比で０．５％、溶銑の炭素濃度が１％変動すれば溶銑比で３．０％に相当する量を補正することにより、溶銑量を含めた配合される転炉の入熱量を一定にするか、あるいは入熱量を３％以内に調整することができる。
【００３０】
【発明の効果】
請求項１〜４記載の溶銑の加熱式貯銑炉を備えた転炉の操業方法は、高炉から出銑した溶銑、あるいは溶銑に予備処理を施した後に加熱手段を備えた貯銑炉に装入し、貯銑炉内の溶銑を加熱して昇熱を行い、貯銑炉内の溶銑温度を次工程の転炉精錬時の溶銑配合比の変動代が少なくとも３％以内になるように調整するので、転炉で配合する溶銑比のバラツキを小さくして吹酸による脱炭精錬の吹き止め時の溶鋼の温度及び炭素濃度の的中率を高め、溶鋼の歩留り低下や酸素原単位の節減と溶鋼の生産性を向上することができる。
【００３１】
特に、請求項２記載の溶銑の加熱式貯銑炉を備えた転炉の操業方法は、加熱手段は誘導加熱を用い、冷材を溶解するので、溶銑に直接に電気抵抗熱を付与して加熱効率を高め、溶銑を増産することができ、転炉の溶銑比、あるいは入熱の必要量を安定させることができる。そして、加熱効率が高く、溶製コストを低減することができる。
【００３２】
請求項３記載の溶銑の加熱式貯銑炉を備えた転炉の操業方法は、次工程の転炉精錬時の溶銑配合比は鋼種ごとの配合比にするので、前チャージの配合条件と脱炭精錬の条件を用い、経過時間による外乱要因を解消することができる。そして、吹き止めの温度及び炭素濃度の目標値への的中率をより高めることができ、安定した脱炭精錬を行うことができる。
請求項４記載の溶銑の加熱式貯銑炉を備えた転炉の操業方法は、溶銑の加熱に夜間の電力を用いるので、溶銑の昇熱に用いる電力コストを低減すると共に、多量の冷材等を安価に溶解して、配合する溶銑を増産することができ、高炉等の前工程の影響を回避することができる。
【００３３】
請求項５記載の溶銑の加熱式貯銑炉を備えた転炉の操業方法は、高炉から出銑した溶銑、あるいは該溶銑に予備処理を施した後に加熱手段を備えた貯銑炉に装入して該貯銑炉内に冷材を溶解するに当たり、前記貯銑炉内の溶銑のトランプエレメント成分を測定し、該溶銑のトランプエレメント値に応じて次工程の転炉精錬時の配合条件を調整するので、転炉に装入する溶銑のトランプエレメント値からそのチャージに配合する屑鉄の配合の種類、量を容易に決定することができ、低級屑鉄の積極的な使用が可能になる。そして、溶鋼の溶製コストの低減と、低級屑鉄の使用に伴うトランプエレメント成分外れを防止することができる。
【００３４】
請求項６記載の溶銑の加熱式貯銑炉を備えた転炉の操業方法は、冷材として屑鉄、あるいはダスト、スラジのいずれか１種以上を添加するので、融点の高い屑鉄等を浸炭による溶融温度低下現象（浸炭作用）を利用して容易に溶解して使用する冷材量を多くすることができ、溶銑の増産と、溶銑の製造コストを低減することができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態に係る溶銑の加熱式貯銑炉を備えた転炉の操業方法に適用される加熱式貯銑炉の全体図である。
【図２】同加熱式貯銑炉のＡ−Ａ矢視断面図である。
【図３】溶銑配合比の頻度を表す図である。
【図４】脱炭精錬の吹き止め的中率の比較を表す図である。
【図５】転炉での低級屑鉄配合量の比較を表す図である。
【符号の説明】
１加熱式貯銑炉
２円筒状の鉄皮
３溝型誘導加熱装置
４貯銑炉
５受銑口
６装入口
７出銑口
８溶銑
９開閉蓋[0001]
BACKGROUND OF THE INVENTION
The present invention provides a converter equipped with a hot metal storage furnace that makes the hot metal components used in the converter uniform and, at the same time, adjusts the temperature and carbon concentration of the hot metal to reduce the variation in the hot metal ratio of the converter. Related to the operation method.
[0002]
[Prior art]
Conventionally, cold materials such as scrap iron and iron oxide are charged into the converter, and then the hot metal discharged from the blast furnace is once received and transported to a hot metal ladle, topped car (mixed car), etc. After performing pretreatment such as dephosphorization, it is transferred to a hot metal ladle for a converter, transported by a crane or the like, and charged into the converter. And molten steel is manufactured by blowing oxygen from the top blowing lance and performing decarburization refining. In the decarburization refining of this converter, the amount of hot metal, the amount of scrap iron, iron oxide, etc. are mixed while referring to the past results of blowing acid so that the temperature and carbon concentration at the time of blowing stop at the end of blowing will be the target values. The amount is determined.
[0003]
However, since the components and temperature of the hot metal fluctuate, decarburization and refining is performed by changing the amount of hot metal in the converter and the amount of scrap iron, iron oxide, etc. When actual results fluctuate and the temperature and carbon concentration deviate from the target values, the temperature and carbon concentration are adjusted to increase the heat by adding Al alloy in decarburization refining or secondary refining by excessive blowing acid (re-blowing). Have been forced. As a countermeasure, as described in Japanese Utility Model Publication No. 62-175058, a heating burner directed to the outlet of the kneading furnace (storage furnace) is arranged to heat the hot metal charged in the kneading furnace. Thus, it has been proposed to suppress heat dissipation and prevent solidification of the slag and perform stable tapping.
[0004]
Furthermore, as described in Japanese Patent Laid-Open No. 1-123014, the hot metal of the blast furnace is received in a storage furnace, and pretreatment such as desiliconization, dephosphorization, and desulfurization treatment is performed on the hot metal as necessary. At the same time, the carbon content is reduced before charging the converter. In this method, preliminary treatment is systematically performed, and decarburization refining is performed using this hot metal, thereby avoiding excessive preliminary treatment, eliminating waste of flux (treatment agent) used for the preliminary treatment, It has been proposed to reduce the amount of carbon used for heat compensation in converters. Further, as described in Japanese Patent Application Laid-Open No. 11-248368, a storage furnace in which a grooved induction heating device and a device for feeding scrap iron from which moisture has been removed by drying is already well known. It is possible to stably perform productivity and operation of the converter by using a molten iron to melt and producing a large amount of molten iron source and supplying it to the converter.
[0005]
[Problems to be solved by the invention]
However, when the storage furnace described in Japanese Utility Model Publication No. 62-175058 is used, it is difficult to heat the entire hot metal in the storage furnace, and the components and temperature of the hot metal cannot always be made constant. The hot metal ratio blended in the converter cannot be adjusted within a predetermined range. As a result, the amount of molten iron in the converter and the amount of scrap iron, iron oxide, etc. fluctuate each time, resulting in deviations from the target values for the temperature and carbon concentration of the blow-off, and removal by excessive blowing acid (re-blowing). It becomes charcoal refining. And the reduction of the refinement yield of molten steel, the increase of the oxygen basic unit by excess blowing acid, the fall of productivity of molten steel, the deterioration of quality, etc. arise.
[0006]
Furthermore, even in the method described in JP-A-1-123014, it is possible to avoid pretreatment such as desiliconization, dephosphorization, and desulfurization of excess hot metal, but temperature drop due to heat dissipation during storage This results in a temperature drop due to the above-described pretreatment and a decrease in the carbon concentration in the molten iron. When this hot metal is charged into a converter and blown acid is used, it is necessary to change the mixing ratio of the hot metal in the converter depending on the temperature and carbon concentration at that time. In particular, in the case of temperature, if the hot metal temperature is low, it is necessary to increase the mixing ratio of hot metal in the converter, and if the hot metal temperature is high, it is necessary to reduce the mixing ratio of hot metal in the converter, Each time, the hot metal ratio blended in the converter changes, and variations occur in the temperature and carbon concentration at the time of blowing, which is the end point of decarburization refining with blowing acid.
[0007]
Further, in the method described in Japanese Patent Application Laid-Open No. 11-248368, since a groove type induction heating device is provided, scrap iron from which moisture has been removed by drying is melted, and the amount of hot metal is increased and supplied to the converter. However, there is no disclosure about making the heat input in the so-called converter constant so that the mixing ratio of the hot metal important for stable blowing acid decarburization and refining in the converter is constant. In each case, the hot metal ratio of the converter changes like the above-mentioned Japanese Utility Model Publication No. 62-175058 and Japanese Patent Application Laid-Open No. 1-123014, and the blowing stop which is the end point of decarburization refining with blowing acid There arises a problem that the temperature and the carbon concentration at the time are varied .
[0008]
The present invention has been made in view of such circumstances, to reduce the variation in the ratio of the hot metal to be blended in the converter, to increase the hot rate of the temperature and carbon concentration of the molten steel at the time of the decarburization refining by blowing acid, improved savings and molten steel productivity yield loss or oxygen consumption rate of molten steel, and to provide operations method of the converter with a heated貯銑furnace hot metal which can reduce the refining costs .
[0009]
[Means for Solving the Problems]
The operation method of the converter equipped with the hot metal heating type storage furnace according to the present invention in accordance with the above object is the hot metal discharged from the blast furnace, or the storage furnace provided with heating means after pretreatment of the hot metal The hot metal in the storage furnace is heated to raise the temperature, and the variation temperature of the hot metal composition ratio in the next step of converter refining is within at least 3%. Adjust so that By this method, the hot metal discharged from the blast furnace, or the hot metal after pretreatment of the hot metal is charged into the storage furnace, the hot metal is heated by an induction heating device, and the hot metal ratio blended in the converter, or Since the hot metal temperature is adjusted so that the difference in heat input is within 3%, the blowing temperature and carbon concentration, which are the end points of decarburization by blowing acid, can be targeted to the target values, and the converter Stable decarburization and refining becomes possible.
Here, if the fluctuation margin of the hot metal ratio of the converter exceeds 3%, in addition to the fluctuation of the heat input of the converter, disturbance factors such as the sensible heat of the converter body and the shape of the inside of the furnace become apparent, and the blowing temperature As a result, the hit rate of carbon concentration decreases rapidly and re-blown acid increases.
[0010]
In the operating method of the converter provided with the hot metal storage furnace according to the present invention, the heating means may use induction heating to melt the cold material. Thereby, the whole hot metal in the storage furnace can be heated, and moreover, since electric resistance heat is directly applied to the hot metal, the heating efficiency can be increased. In addition to easily adjusting the temperature of the hot metal in the storage furnace, melt the cold material to increase the production of hot metal, and mix according to the hot metal ratio to be added to the converter or the required amount of heat input. Can do.
[0011]
Furthermore, in the operating method of the converter provided with the hot metal storage furnace of the hot metal according to the present invention, the hot metal compounding ratio at the time of the converter refining in the next step is preferably the mixing ratio for each steel type. This makes it possible to perform hot metal decarburization refining in accordance with the hot metal ratio or heat input of the converter for each steel type, and accurately predict the hot metal ratio or heat input, which is the blending condition for the next charge. Disturbance factors due to time can be eliminated. And the blow-off temperature and the carbon concentration can be targeted by the target values.
In the operation method of the converter equipped with the hot metal storage furnace according to the present invention, it is also possible to use nighttime electric power for heating the hot metal iron. As a result, it is possible to reduce the cost of electric power used for heating, to melt a large amount of cold material, etc., and to increase the amount of hot metal to be blended in the converter to operate at a high hot metal ratio. it can. And decarburization refining by a high hot metal ratio can be performed stably.
[0012]
Furthermore, in a method of operating a converter provided with a hot metal storage furnace for the purpose, the hot metal discharged from the blast furnace or a storage furnace equipped with a heating means after pretreatment of the hot metal is installed. In order to melt the cold material in the storage furnace, the trump element component of the hot metal in the storage furnace is measured, and the blending conditions at the time of converter refining in the next step according to the trump element value of the hot metal Can also be adjusted. By this method, after adding a cold material in the storage furnace and melting it by the heating means, it is possible to grasp the trump element component of the hot metal. Depending on this value, the type and amount of scrap iron to be blended in the converter can be determined, so that the scrap iron used in the converter is within the allowable range of the trump element component, and the increased use of lower scrap iron and the trump element component are taken into account. Appropriate use of low-grade scrap iron can be made possible.
[0013]
Moreover, in the operation method of the converter provided with the hot metal storage furnace, it is preferable that the cold material is one or more of scrap iron, dust, and sludge. As a result, scrap iron or dust having a high melting point can be easily melted by utilizing the melting temperature lowering phenomenon (carburizing action) accompanying carburizing, and it becomes easy to apply heat necessary for this melting. The amount of material can be increased. Furthermore, since highly evaporable impurities contained in lower scrap iron can be removed, impurities such as zinc and tin can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
FIG. 1 is an overall view of a heating storage furnace applied to a converter operating method provided with a hot metal storage furnace according to an embodiment of the present invention, and FIG. 2 shows the heating storage tank. 3 is a cross-sectional view taken along the line AA of the furnace, FIG. 3 is a frequency of hot metal mixing ratio, FIG. 4 is a comparison of blow-through rate of decarburization refining, and FIG. 5 is a comparison of low scrap iron mixing amount in a converter. FIG.
[0015]
As shown in FIGS. 1 to 2, a heating storage furnace 1 used in a method for operating a converter provided with a hot metal storage furnace according to an embodiment of the present invention has a cylindrical iron skin. 2 shows a rotatable storage furnace 4 lined with a refractory (not shown), and a grooved induction heating apparatus 3 as an example of a heating apparatus respectively disposed on both sides of a cylindrical body of the storage furnace 4. Is provided. Further, above the cylindrical body of the storage furnace 4, a receiving port 5 provided with an opening / closing lid 9 for charging the molten iron into the furnace by a conveying means such as a crane, and scrap iron as an example of a cold material. A charging inlet 6 provided with an opening / closing lid (not shown) for charging is provided, and a hot metal outlet 7 for discharging the hot metal 8 inside the hot metal pan or the like is provided.
[0016]
Next, the operation method of the converter provided with the hot metal storage furnace according to the present embodiment using the heating storage furnace will be described.
The hot metal discharged from the blast furnace is transported by a topped car, subjected to preliminary treatments such as desiliconization, dephosphorization, and desulfurization, then placed in a hot metal ladle, lifted by a crane, and the open / close lid 9 of the storage furnace 4 is opened to receive a receiving port. The hot metal is charged into the furnace from 5. The hot metal was repeatedly charged and 1000 tons of hot metal 8 was stored in the furnace. And the hot metal 8 was sampled, the temperature and the carbon concentration were measured, and since the temperature was as low as 1270 ° C., each of the groove type induction heating devices 3 was energized, and heating was started at an output of 3.5 MW. As the temperature of the hot metal 8 was raised to 1340 ° C by increasing the output in order and induction heating, continuously adding low-grade scrap iron, which is recovered scrap in the city, at a rate of 1.0 ton / min. To dissolve the scrap iron. As the scrap iron dissolves, the carbon concentration of the hot metal 8 decreases. When the carbon concentration of the hot metal 8 falls below 4.0% by mass, the hot metal 8 is opened by opening the opening / closing lid 9 of the storage furnace 4. 5 was charged into the furnace, and scrap iron was added and new hot metal was charged repeatedly. As a result, 1480 tons of hot metal 8 having a hot metal temperature of 1340 ° C. and a carbon concentration of 4.0% by mass could be produced. The trump element component of the hot metal 8 in the storage furnace 4 is typically, for example, 0.008 mass% copper (Cu), 0.001 mass% tin (Sn), 0.05 mass chromium (Cr). %Met.
[0017]
Next, the charge for decarburizing and refining the converter is a low-carbon molten steel with a general carbon concentration of 0.10% by mass or less. The one most similar to the charge was selected by reference, and the hot metal 8 was discharged into a 343 ton hot metal ladle and charged into the converter using a crane so that the hot metal ratio was 91.0% under this condition. . Thereafter, 34.0 tons of scrap iron was charged into the converter. Then, auxiliary raw materials such as quick lime and iron ore were added, and decarburization refining was performed with the same other blowing acid conditions such as the amount of blowing acid from the top blowing lance and the height of the top blowing lance. As a result, the temperature of the blown-out molten steel, which is the end point of decarburization refining, can be set to 1685 ° C. and the carbon concentration to 0.07% by mass, the target values of temperature 1675 to 1690 ° C., and carbon concentration 0.04 to 0.06. The target was in the range of mass%. Decarburization refining using a converter includes refining medium carbon molten steel with a carbon concentration of over 0.10 and less than 0.30% by mass, and high carbon molten steel with a carbon concentration of over 0.30 and 0.80% by mass. Although it was performed for each steel type, both can be targeted at the target temperature and carbon concentration, there is no re-blowing due to out-of-temperature or high carbon concentration, and the carburized material at the time of steel output due to too low carbon concentration The addition of was also reduced.
[0018]
In FIG. 3, when the decarburization and refining of the converter of low-carbon molten steel is performed, the molten iron mixture ratio (molten iron ratio) of the converter is energized to each of the grooved induction heating devices 3 of the storage furnace 4 to dissolve the scrap iron and In the case of the present invention in which hot metal is added and heated, and the temperature and carbon concentration of hot metal 8 are made constant, and the state of the conventional hot metal mixing ratio in which the temperature and carbon concentration of hot metal are not adjusted, the case of the present invention is shown. The ratio of molten iron in the converter is 89-92%, the variation can be reduced to 3% or less, and the heat input determined by the molten iron temperature and carbon concentration of the converter is also stably adjusted to a narrow range of 3% or less. I was able to. As a result, as shown in FIG. 4, the target ratio of the temperature and carbon concentration during the decarburization and refining of the converter can be set to 98% or more, and the re-blown acid generation rate is 2.0%. I was able to:
[0019]
On the other hand, the hot metal mixing ratio when the conventional hot metal temperature and carbon concentration are not adjusted is in the range of 86 to 93.5%, and it is necessary to add carbonaceous materials such as graphite, coke, and coal. An increase in the sulfur (S) concentration therein occurred. Moreover, despite the fact that decarburization and refining were carried out with the same conditions as the amount of acid blown from the top blowing lance and the height of the top blowing lance, the temperature and carbon during the decarburization and refining of the converter The accuracy rate for the target concentration is 89%, the rate of re-blown acid is increased to 9.0%, the drop in molten steel due to re-blown acid, the increase in oxygen intensity, the drop in molten steel productivity, etc. Occurred.
[0020]
In addition to adjusting the temperature of the hot metal 8 by each of the grooved induction heating devices 3 and adjusting the carbon concentration using the storage furnace 1 so as to be in a certain range, at the same time, melting the scrap iron and the like Since the production is increased, it is possible to avoid the influence of the lack of hot metal resulting from fluctuations in the operation of the blast furnace, which is the previous process. Furthermore, the matching with the continuous casting equipment, which is a subsequent process, becomes better, the operation schedule of the converter operation and the casting operation can be efficiently operated, and the reduction in productivity and overall cost of the entire steelmaking process can be fully expressed. . And the quality and productivity of molten steel and slab can be improved by the stable operation of a converter and continuous casting equipment. Furthermore, since the hot metal 8 is heated directly using electric resistance heat, the heat efficiency of heating can be maintained at a high level of 80% or more, and the low-cost heating is performed by actively utilizing the nighttime electric power which is low in power consumption. be able to.
[0021]
Further, since scrap iron is added into the storage furnace 4 and dissolved quickly by utilizing the carburizing action, and the components of the molten iron 8 are made uniform, the molten iron 8 after melting of the scrap iron is sampled and analyzed. In addition, Cu, Sn, Cr, etc., which are the trump element components of the hot metal 8 to be blended in the converter, can be grasped in advance. Therefore, at the time when the amount of hot metal 8 is determined in the converter, the permissible value for each element of the trump element component can be easily obtained from the standard value of the trump element of the generally defined steel material.
[0022]
FIG. 5 shows the ratio of the amount of lower scrap to the total amount of scrap iron in the converter. When scrap iron is previously dissolved in the storage furnace 4, the amount of scrap iron dissolved is added and 30% lower scrap is added. For example, copper (Cu) 0.008 mass%, tin (Sn) 0.001 mass%, chromium (Cr) 0.05 mass % Could be maintained. On the other hand, in the case of the conventional case in which the lower scrap is not dissolved in advance, the lower scrap to be used has a low blending amount of 10% because it has to be formulated in consideration of the variation of the trump element component of the lower scrap. And although the trump element component was able to suppress the deviation from the standard value of the steel material, the melting cost of the molten steel increased as much as the amount of inexpensive low-grade scrap iron used was reduced. In the present embodiment, the scrap iron is used as the cold material. However, it is possible to use the dust generated from the converter in a lump shape or the dust collecting sludge formed by drying.
[0023]
【Example】
Next, an embodiment of a method for operating a converter provided with a hot metal storage furnace will be described. The hot metal discharged from the blast furnace was pretreated for desiliconization, dephosphorization, and desulfurization. This hot metal is conveyed as it is with a topped car, 500 tons of 1270 ° C. hot metal is charged into the storage furnace through the hot metal ladle, energized to the groove type induction heating device, and heated to 1340 ° C. with an output of 10 MW, The hot metal having a temperature of 1270 ° C was repeatedly charged and heated by the grooved induction heating device, and 1000 tons of hot metal having a temperature of 1340 ° C was stored. Then, scrap iron is continuously added to the hot metal at 1340 ° C. at a rate of 1.0 ton / min, and scrap iron is melted while the energized state is continued. In order to maintain 0% by mass, melting of this scrap iron and charging of new hot metal conveyed by a topped car were repeated to produce 1480 tons of hot metal. This hot metal was blended so that the variation in the hot metal ratio of the converter was within 3%, and a high hot metal ratio operation was performed.
[0024]
In Example 1, in order to produce low carbon molten steel having a carbon concentration of 0.10% or less, the hot metal temperature was set to 1340 ° C., the molten iron ratio of the converter was 91.0%, and the remaining 9.0% was lower scrap iron. The decarburization refining was carried out under the same blowing acid conditions with the same amount of acid feeding, lance height, etc., which were the past blowing acid conditions of low carbon molten steel having a carbon concentration of 0.10% or less. As a result, the temperature of the blow-stop, which is the end point of decarburization refining, could be targeted to the target value of 1680 ° C. and the carbon concentration of 0.05%.
[0025]
In Example 2, since the low carbon molten steel having a carbon concentration of 0.10% or less is melted, the output of the groove type induction heating device is adjusted so that the hot metal ratio of the converter becomes 90 to 92%. The temperature is 1340 to 1370 ° C., and the remainder other than the molten iron of the converter is blended with low-grade scrap iron, and the amount of oxidization and the lance height are the past blowing acid conditions of low-carbon molten steel with a carbon concentration of 0.10% or less. The decarburization refining of 10 charges was performed under the same blowing acid conditions. And the hit ratio with respect to the target value of the temperature and carbon concentration of the blow stop which is the end point of decarburization refining, and the generation rate of re-blown acid were investigated. As a result, the hit ratio with respect to the target values of the temperature and the carbon concentration of the blow stopper could be 98%, and the re-blown acid ratio could be only 2%. Since the decarburization refining with blowing acid is stable, the melting yield of molten steel is good, the refining time is greatly shortened, and the productivity is improved.
[0026]
In Example 3, in order to produce low carbon molten steel having a carbon concentration of 0.10% or less, the hot metal ratio of the converter was set to 90.4% using hot metal at a temperature of 1340 ° C., and the trump element of the hot metal at this time Analyzing the components, grasping the values of Cu, Cr, Sn, and Pb as typical ones, out of the total amount of 9.6% scrap iron, 30% lower scrap iron (the remaining 70% is high quality scrap iron such as crops) ) And decarburization refining with blowing acid. As a result, the blow-off temperature, which is the end point of decarburization refining, was able to hit the target values of 1690 ° C. and the carbon concentration of 0.09%. Moreover, the trump element component can be made to be steel material standards of Cu 0.10% by mass or less, Cr 0.10% by mass or less, Sn 0.02% by mass or less, and Pb 0.02% by mass or less. And the total usage-amount of the low-grade scrap iron mix | blended with a converter could be increased, and the trump element component removal of molten steel could be prevented reliably.
[0027]
In addition, with regard to medium carbon steel and high carbon steel, the melting iron melting and the hot metal temperature and carbon concentration are adjusted by the grooved induction heating device so that the hot metal ratio of the converter is within 3%. Although decarburization and refining was performed under the same acid steel blowing acid conditions, the hit ratio with respect to the target value could be 98% or more, and the re-blown acid ratio could be less than 2%. Similar effects were obtained. In addition, since the trump element component of the molten steel was measured in advance, and the selection and mixing amount of scrap iron were made so as to be below the steel material standard of the trump element, there was no deviation of the trump element component of the molten steel.
[0028]
On the other hand, low temperature molten steel with a carbon concentration of 0.10% or less was produced without adjusting the temperature and carbon concentration of the hot metal, but the hot metal ratio of the converter greatly varied as 86-93.5%. However, the temperature and carbon concentration of the decarburization refining with blown acid deviate from the target values, the hit ratio is greatly reduced to 89%, and the sulfur (S) concentration in the molten steel increases due to the addition of carbonaceous materials. Reduction in molten steel yield, increase in oxygen intensity, decrease in molten steel productivity, etc. due to re-blown acid occurred. In addition, as the hot metal ratio fluctuates, the scrap iron mixing ratio also fluctuates, and scrap iron with a large variation in the trump elements is blended. It becomes an operation to increase the amount. And the usage-amount of cheap lower scrap iron decreased with the increase in the compounding quantity of high quality scrap iron.
[0029]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention. For example, in addition to scrap iron, dust, and sludge as a cooling material, an iron source with a high carbon content such as a mold can be used to dissolve the material by an induction heating device. Furthermore, as a decarburization refining furnace, in addition to the converter, the hot metal supplied to the top-bottom converter, electric furnace, etc. is heated to adjust the temperature and carbon concentration, adjust the trump element component, and apply it for prediction. The hot metal supplied can be increased. The adjustment of the hot metal ratio in the converter is an amount corresponding to 0.5% hot metal ratio when the hot metal temperature fluctuates by 10 ° C and 3.0% hot metal ratio when the carbon concentration of the hot metal fluctuates by 1%. By correcting the above, it is possible to make the heat input amount of the converter including the molten iron amount constant, or to adjust the heat input amount within 3%.
[0030]
【The invention's effect】
The method of operating a converter provided with a hot metal storage furnace according to claims 1 to 4 is provided in a hot metal discharged from a blast furnace or a storage furnace equipped with a heating means after pretreatment of the hot metal. The hot metal in the storage furnace is heated to raise the temperature, and the hot metal temperature in the storage furnace is adjusted so that the fluctuation margin of the hot metal composition ratio during the refining of the next process is within 3% Therefore, the variation in the ratio of the hot metal to be blended in the converter is reduced to increase the hot rate of the molten steel temperature and carbon concentration during the decarburization refining with blowing acid, thereby reducing the yield of molten steel and the reduction of oxygen intensity. And the productivity of molten steel can be improved.
[0031]
In particular, in the method of operating a converter provided with the hot metal storage furnace according to claim 2, since the heating means uses induction heating and melts the cold material, the electric resistance heat is directly applied to the hot metal. Heating efficiency can be increased, hot metal production can be increased, and the hot metal ratio of the converter or the required amount of heat input can be stabilized. And the heating efficiency is high and the melting cost can be reduced.
[0032]
In the method of operating a converter equipped with the hot metal storage furnace according to claim 3, the mixing ratio of the hot metal during the refining of the next process is the mixing ratio for each steel type. By using the conditions of charcoal refining, disturbance factors due to elapsed time can be eliminated. And the hit ratio to the target value of the temperature and carbon concentration of a blowing stop can be raised more, and the stable decarburization refining can be performed.
The operation method of the converter provided with the hot metal storage furnace according to claim 4 uses electric power at night for heating the hot metal, so that the power cost used for heating the hot metal is reduced and a large amount of cold material is used. Etc. can be melted at low cost to increase the amount of hot metal to be blended, and the influence of the previous process such as blast furnace can be avoided.
[0033]
The operating method of the converter provided with the hot metal storage furnace of claim 5 is charged into the hot metal discharged from the blast furnace, or after pre-treatment of the hot metal, the storage furnace provided with heating means. Then, in melting the cold material in the storage furnace, the trump element component of the hot metal in the storage furnace is measured, and the blending conditions at the time of converter refining in the next step are determined according to the trump element value of the hot metal. Since it adjusts, the kind and quantity of scrap iron mix | blended with the charge can be easily determined from the trump element value of the hot metal charged in the converter, and the aggressive use of low-grade scrap iron becomes possible. And the reduction of the melting cost of molten steel and the trump element component removal accompanying use of low-grade scrap iron can be prevented.
[0034]
The operation method of the converter provided with the hot metal storage furnace according to claim 6 adds scrap iron or any one or more of dust and sludge as a cold material, so that scrap iron having a high melting point is carburized. It is possible to increase the amount of cold material that is easily melted and used by utilizing the melting temperature lowering phenomenon (carburizing action), and it is possible to increase the production of hot metal and reduce the manufacturing cost of the hot metal.
[Brief description of the drawings]
FIG. 1 is an overall view of a heating storage furnace applied to a converter operating method provided with a hot metal storage furnace according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of the heating type storage furnace.
FIG. 3 is a diagram showing the frequency of the hot metal mixture ratio.
FIG. 4 is a diagram showing a comparison of blow-through rate of decarburization refining.
FIG. 5 is a view showing a comparison of blending amounts of lower scrap iron in a converter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating type storage furnace 2 Cylindrical iron skin 3 Groove type induction heating apparatus 4 Storage furnace 5 Receiving port 6 Loading port 7 Outlet port 8 Hot metal 9 Opening and closing lid

Claims

The hot metal discharged from the blast furnace, or after pretreatment of the hot metal, is charged into a storage furnace equipped with heating means, the hot metal in the storage furnace is heated to raise the temperature, and the storage furnace The hot metal storage type is characterized in that the hot metal temperature is adjusted so that the fluctuation ratio of the hot metal composition ratio at the time of converter refining of the charge in the next process is at least 3% of the charge other than the charge. Operation method of a converter equipped with a furnace.

The operating method of the converter provided with the hot metal storage-type storage furnace of Claim 1 WHEREIN: The said heating means uses induction heating, and comprises a hot metal storage-type storage furnace characterized by melt | dissolving a cold material. How to operate the converter.

The operating method of the converter provided with the hot metal storage furnace of the hot metal according to claim 1 or 2, wherein the hot metal compounding ratio at the time of converter refining in the next step is a mixing ratio for each steel type. Of operating a converter equipped with a heated storage furnace.

In the operating method of the converter provided with the hot metal heating type storage furnace of any one of Claims 1-3, the electric power of nighttime is used for the heating of the hot metal, The heating type storage of the hot metal characterized by the above-mentioned. Operation method of a converter equipped with a firewood furnace.

In melting the cold material according to claim 2, the trump element component of the hot metal in the storage furnace is measured, and the blending conditions at the time of converter refining in the next step are adjusted according to the trump element value of the hot metal A method of operating a converter equipped with a hot metal storage furnace characterized by the above.

The operating method of the converter provided with the hot metal storage furnace of the hot metal according to claim 2 or 5, wherein the cold material is added with at least one of scrap iron, dust, and sludge. A method of operating a converter equipped with a heating storage furnace.