JP4016500B2

JP4016500B2 - Blasting method for suppressing metal adhesion in converter refining furnace

Info

Publication number: JP4016500B2
Application number: JP26529198A
Authority: JP
Inventors: 一郎菊地; 秀栄田中; 寛治日出; 泰三瀬良
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 1998-09-18
Filing date: 1998-09-18
Publication date: 2007-12-05
Anticipated expiration: 2018-09-18
Also published as: JP2000096119A

Description

【０００１】
【発明の属する技術分野】
本発明は転炉型精錬炉において、炉内への原料装入操作を円滑に行なうと共に、炉口装置や炉内側壁の円滑な保全を図るために、炉口及び炉内側壁への地金付着を抑制する転炉吹錬方法に関するものである。
【０００２】
【従来の技術】
転炉精錬において、吹錬中に発生するスピッティング、スロッピングにより飛散した溶鋼及びスラグの一部は炉口や炉内側壁に地金として付着する。付着した地金はヒ−トを続けるにつれて成長し、その大きさがある限度以上になると溶銑及びスクラップ装入の障害になるばかりでなく、吹錬中の浴中への落下や溶融流下により操業に大きな支障をきたす。そこで、上記の付着地金は操業に支障をきたす大きさ以上になる前に除去する必要がある。
【０００３】
炉口地金を除去する伝統的方法としては、スクラップシュ−トを炉口地金部にぶつけ物理的に除去する方法がある。しかしながら、この方法は転炉非吹錬時に実施しなければならないので、非製鋼時間の増大を招き転炉生産性を著しく阻害する。また、スクラップシュ−トを炉口地金部に直接ぶつけるため、その衝撃で炉口レンガの脱落をおこす危険性がある。
【０００４】
一方、転炉における生産性を阻害することなく吹錬中に発生する排ガスを２次燃焼させ炉口や炉内側壁地金を溶解除去する方法が提案されている。
例えば特開平６−２４８３２３号公報は、吹錬中に、吹錬用主ランスの側壁に設けた吹錬用ランス軸に対してθ＝２５〜４０°の範囲内の角度で下向きに取付けられた２次燃焼用酸素供給ノズルから湯面に向けて２次燃焼用酸素を吹き付け、転炉排ガスを炉内で燃焼させ、発生した熱で炉口に付着した地金を溶解・除去する方法（先行技術１）を開示している。
【０００５】
また、特開昭６１−１３９６１６号公報は、転炉精錬中に、吹錬用ノズル及び炉口地金溶解用ノズルを備えた吹錬用ランスを用いて、炉口地金溶解用ノズルから転炉炉口に向けて空気を噴射させることにより炉口地金を溶解・除去する方法（先行技術２）を開示している。
【０００６】
【発明が解決しようとする課題】
本発明者らは、転炉炉口や炉内側壁地金の溶解除去技術の開発に際して、地金の溶解・除去中に耐火物に対する損傷を極力防止し、しかも効率的に地金除去を行ない生産性を確保することを前提として、下記問題の解決を図ることを課題とした。
【０００７】
炉口に付着し成長した地金が、溶銑やスクラップの転炉装入作業に支障をきたさないようにし、吹錬中における付着地金の離脱・落下や溶融流下による吹錬終了時における溶鋼温度や成分の異常発生を未然に防止すると共に、炉口耐火物の溶損を回避しつつ地金の付着・成長を抑制して、炉口装置や炉内側壁の補修・維持を良好に行なうために、地金付着状態を良好に管理する必要がある。そのためには、炉口地金溶解用の酸素を地金付着位置に的確に、且つその位置に適正圧力の酸素ガスを適量だけ供給することにより、付着地金を溶解・除去しなければならない。即ち、付着地金が的確に溶解・除去されるように、炉口地金溶解用酸素の供給を制御しなければならない。
【０００８】
上記観点によれば、先行技術では次の問題がある。
先行技術１では、２次燃焼用酸素の噴射方向が比較的鉛直下向きに近いので、炉内排ガスに巻き込まれながらＣＯガスを２次燃焼させ、炉内から炉口にかけての２次燃焼に大部分が消費される。従って、その際発生する高熱による２０００℃以上の高温ガスは、転炉炉口地金の溶解のみならず転炉炉口金物および炉口耐火物に著しい損傷を与え易い。
【０００９】
先行技術２によれば、炉口地金溶解用の酸素源として空気を用いるので、酸素を噴射させる場合よりも噴射量が増加し、炉口耐火物の金物の溶損を防止することができる。ところが、空気では酸素濃度が低いので、炉口地金の溶解に時間を要し、効率が悪い。
【００１０】
ところで、付着地金の下に存在する耐火物、即ち下地耐火物の損傷を抑制しつつ広範囲に付着した地金を均一に効率よく溶解する制御をするためには、１ヒート内での吹錬時期により地金溶解用酸素ガス中の純酸素流量を適切に変えることが必要である。地金溶解用ノズルから供給される酸素ガス流は、炉内ガス流れにより大きく変わる。ここで、炉内ガス流の状態は、その時点における浴の成分組成と吹錬用酸素流量に依存して変化する。従って、地金溶解用酸素ガス中の純酸素流量は、その時点における吹錬用酸素の流量により適切に定めなければならない。しかしながら、先行技術には、このような技術的事項の開示はみられない。
【００１１】
このように、先行技術にはそれぞれ問題があり、この発明が解決すべき課題の中心である、地金溶解用酸素の供給を良好に制御することはできない。
従って、この発明の目的は、転炉における溶鋼の生産性を確保することを前提とし、炉口や炉内側壁の耐火物を溶損させることなく、地金の付着状態を良好に管理する吹錬方法を提供することにある。
【００１２】
【課題を解決するための手段】
本発明者らは、上述した観点から研究を重ね、下記知見を得た。
１．先ず、炉口及び炉内側壁に地金が付着するのは、吹錬のどの時期に多いのかについて試験した。その結果、地金付着時期は、吹錬の比較的初期に多量に付着するとの知見を得た。そこで、付着地金の溶解操作は少なくとも、吹錬初期を含んで実施すべきであるとの着想を得た。
【００１３】
２．次に、付着地金の溶解操作の弊害を回避する必要がある。即ち、吹錬の末期において、炉口や炉内側壁に付着した地金を、地金溶解用酸素ガスにより溶解・除去すると、浴中への地金の溶融流下や地金の塊りの落下により、浴中不純物成分の上昇や浴温度の低下等が起こり、吹錬終点時の成分組成及び溶鋼温度の制御性が悪化して、目標成分組成外れや目標温度外れが発生し、操業の安定性を害し、生産性の低下、品質の低下あるいは生産歩留の低下等、弊害が発生し易くなる。従って、吹錬終了時点における溶鋼の温度及び成分組成の目標外れを防止するためには、少なくとも、吹錬末期に行なう温度及び成分分析用試料採取の後、いわゆるサブランス計測実施の後には、地金溶解用酸素を供給しないことが望ましい。そして、この間は、地金溶解用ノズルが目詰まりを起こさないようにするために、当該ノズルからパージガスを流し続ける必要がある。
従って、転炉吹錬中に炉口や炉内側壁付着地金を溶解・除去するに際しては、吹錬末期にはこのような操作をしてはならない。
【００１４】
３．付着地金を広範囲領域にわたりできるだけ均一に溶解し、且つ地金の下地にある耐火物を損傷させないようにするためには、炉内ガス流れの状態に応じて地金溶解用酸素ガスを供給することが効果的であること、即ち、吹錬用酸素ガスの流量に応じた流量の地金溶解用酸素ガスを供給することが効果的であることを知見した。
この発明は上記事項を基本的知見としてなされたものであり下記の通りでる。
【００１５】
請求項１記載の発明は、溶銑を主たる鉄源として、上吹き又は上底吹き酸素により精錬を行なう転炉型精錬炉において、吹錬用ノズルが下端に設けられ、地金溶解用ノズルが外周面に設けられ、前記地金溶解用ノズルからは酸素ガス又はパージガスを吹錬用酸素ガスとは独立に制御して供給することができるランスを用い、炉口及び／又は炉内側壁に地金が付着するのを抑制する際に、吹錬期間を吹錬前期と吹錬後期とに区分し、前記吹錬前期には前記地金溶解用ノズルから酸素ガスを供給して炉口及び／又は炉内側壁に付着した地金を溶解・除去し、次いで吹錬後期には、前記地金溶解用ノズルからパージガス又はこのパージガスと純酸素に換算して所定流量以下の酸素ガスとを流して、当該地金溶解用ノズルの目詰まりを防止しつつ吹錬する吹錬方法において、前記吹錬前期と後期との境界時点を、吹錬の開始から吹錬全予定時間の５０〜９５％の範囲内の時点とし、前記吹錬前期に流す地金溶解用酸素ガス中の純酸素流量を吹錬用酸素ガス流量の３〜１０％の範囲内とし、そして、前記吹錬後期においてパージガスと共に前記地金溶解用ノズルから流す酸素ガス中の純酸素流量を、前記吹錬前期に流した地金溶解用酸素ガス中の純酸素流量の５０％以下に制限することに特徴を有するものである。
【００１６】
請求項２記載の発明は、請求項１記載の吹錬方法において、前記地金溶解用ノズルから噴射させる酸素の噴射方向を、前記ランスの長手方向軸心線とのなす角度が４０〜９０°の範囲内であって、且つ下向き乃至水平方向にすることに特徴を有するものである。
【００１７】
請求項３記載の発明は、溶銑を主たる鉄源として、上吹き又は上底吹き酸素により精錬を行なう転炉型精錬炉において、前記転炉型精錬炉へ装入する溶銑のＳｉ濃度が０．１５質量 % 以下であり、前回ヒートのスラグを１０ kg/t-steel 以上炉内に残留させ、今回ヒートの炉内スラグ量を３０ kg/t-steel 以下とし、且つ、請求項１または２記載のいずれかの条件で吹錬することに特徴を有するものである。
【００２０】
【発明の実施の形態】
次に、この発明の望ましい実施の形態を説明する。
図１は、この発明の方法を実施するために用いる設備例の概念図である。
【００２１】
溶銑１及び造滓材２が装入された転炉３の上方から、炉口４を通って炉内にランス５を挿入する。ランス５には、下端に吹錬用酸素ノズル６を備え、下端から上方の所定位置に、地金溶解用ノズル７を備えている。地金溶解用ノズル７からのガス噴射方向は、鉛直に設定されるランスの長手方向軸心線とのなす角度が４０〜９０°の範囲内の下向き乃至水平方向である。これにより、炉口４及びその絞り部に付着した地金（特に断らない限り「炉口地金」という）、並びに炉内側壁に付着した地金（特に断らない限り炉口地金と合わせて「地金」という）のいずれをも溶解・除去する。ランス５の構造としては、吹錬用酸素ノズル６に酸素ガスを供給する酸素供給管、地金溶解用ノズル７に酸素ガス及び／又はパージガスを供給する酸素・パージガス供給管、並びにランスの冷却用給水管及び排水管の四重管構造となっている。こうして、地金溶解用酸素の供給経路を、吹錬用酸素の供給経路から独立させて制御し得るようにしてある。
【００２２】
（１）上記設備を用いて、吹錬用酸素ノズル６から所定の流量ａ（Ｎｍ³／ｍｉｎ）の酸素ガスを噴射して、溶銑を吹錬する。一方、地金溶解用ノズル７から所定の流量ｂ（Ｎｍ³／ｍｉｎ）の酸素ガスを噴射して、炉口４及びその絞り部に付着した地金８、並びに炉内側壁に付着した地金８’を溶解し、除去する。但し、ここで重要なのは、地金８、８’を溶解・除去するに当たっては、地金の下地にある耐火物まで損傷してはいけないこと、及び通常は炉口の絞り部内面のほぼ全面に亘って付着した地金を均一に溶解・除去することである。これを実現するための地金溶解用酸素ガス中の純酸素流量を、吹錬用酸素ガスの流量に関して求めた。
【００２３】
３００ｔ／ｃｈの上底吹き転炉を用い、ランスとして、６孔ラバールノズルからなる吹錬用ノズルが下端に設けられ、地金溶解用ノズルがランス下端からの所定高さ位置の２段に、各々、ランス外周に沿って１０個のノズルが設けられ、ノズル径が８ｍｍのものを使用した。地金溶解用酸素の噴射方向と、ランスの軸心線とのなす角度θ（図１参照）は９０°、即ち水平方向に酸素を噴射させた。吹錬用酸素の流量ａとして、１７０〜５００Ｎｍ³／ｍｉｎ、及び７００〜１０００Ｎｍ³／ｍｉｎの２水準で行なった。
【００２４】
地金の溶解試験は、炉口地金の付着量が基準値に達したときに行なった。吹錬用酸素の流量ａと、地金溶解用酸素の流量ｂとの比率（ｂ／ａ）×１００（％）を、０〜７０％の範囲内の種々の値に変化させて行なった。そして、炉口地金の溶解に伴う炉口径の拡大速度より炉口地金の溶解速度を求め、これを溶解速度指数で表わした。この指数は大きいほど溶解速度が速く、地金除去に望ましいことを表わす。また、炉口耐火物の溶損速度を測定し、指数で表わした。この指数は小さいほど溶損速度が遅く望ましいことを表わす。
【００２５】
図２に、ｂ／ａと炉口地金の溶解速度との関係を示し、図３に、ｂ／ａと炉口耐火物の溶損速度との関係を示す。図２及び３からわかるように、ｂ／ａが１〜５０％の範囲内の場合には、炉口地金を速やかに溶解することができ、しかも、炉口耐火物の溶損量も少ない。特に、ｂ／ａが３〜１０％の場合に良好な結果が得られた。
【００２６】
以上より、地金溶解用酸素ガス中の純酸素流量ｂ（Ｎｍ³／ｍｉｎ）は、吹錬用酸素ガスの流量ａ（Ｎｍ³／ｍｉｎ）の３〜１０％の範囲内において供給することにより、目標とする地金溶解を行なうのがよい。
【００２７】
（２）次に、１ヒートの吹錬期間を、前期と後期とに区分し、前期に、上記地金溶解用酸素の供給条件により地金溶解操作を行なう。その理由は、少なくとも、地金の付着速度の大きい時期を含んで地金溶解を行なうことにより、効率的に地金が溶解されること、また、こうすることにより、既に炉口付着地金が多量に形成されているヒートの終了後に、非吹錬時に次ヒートの原料装入作業確保のための地金除去操作をしなければならないような事態を発生させないためにも効果的である。炉口への地金付着速度が大きい時期は、吹錬の比較的初期であるからである。
【００２８】
図４は、脱炭吹錬１ヒートの経過時間とダスト発生量との関係を示す。これによれば、ダストの発生量は吹錬の初期に多い。そして、図５は、従来の吹錬方法において、吹錬初期のダスト発生量と一定ヒート数の操業で炉口地金を除去した回数との関係を示す。これによれば、初期ダスト発生量が多くなるほど、炉口地金除去頻度が多くなる。従って、図４及び図５より、炉口地金は、吹錬初期のダスト発生量が多い時期にその付着形成速度が早いことがわかる。
【００２９】
地金溶解操作を行なう時期は、地金形成速度が早い時期を含んでいることが重要であるから、その時期は吹錬初期から、吹錬末期のいわゆるサブランス計測実施の前程度までなら通常は問題とならない。また、地金付着が多量の状態でのヒートであれば、吹錬終点予定時の前、全吹錬予定時間の５％程度逆上った時点まで地金溶解を継続しても差し支えないし、少量の地金付着であれば吹錬半ばで地金溶解を終了してもよい。
【００３０】
このように、地金溶解時期の終了時点は、一概に定めることは必ずしも有利ではないから、吹錬前期と後期との境界時点は、一例として、吹錬の開始から吹錬全予定時間の５０〜９５％の範囲内のある時点とすればよい。また、他の例として、吹錬の開始から吹錬全予定時間の７０〜９５％の範囲内のある時点とすればよい。いずれを選択するかは、操業全般の転炉の地金付着の状況、精錬対象鋼種や当該溶製鋼の成品仕様、炉口耐火物の損耗状況その他、設備及び操業条件を勘案して個々のケースで決めるのがよい。
（３）次に、地金溶解操作をしない吹錬後期においては、地金溶解用ノズルからはパージガスを流す。この場合、当該ノズルの目詰まりを防止することが目的である。従って、通常はノズル出口で２気圧（絶対圧力）程度ないしそれより若干高め程度のガス圧力を保持しなければならないことを前提とし、その上で適切な、ガス流量を確保するようにする。かかるパージガスの流量は経験的に決定すればよい。但し、パージガス種は、低窒素鋼種の溶製時には、吹錬末期ではアルゴンガス等の不活性ガスを使用すべきである。窒素ガスは、吹錬末期以後での脱窒効果は期待できないので低窒素鋼種では使用できないが、高窒素鋼種を溶製する場合はこの限りではない。また、パージガスは地金溶解用ノズル７を用いる関係もあり、酸素ガスを所定値以下に制限すれば、パージガスと一緒に流しても差し支えない。所定値とは一般に、溶解地金の塊り落下を防止する観点から、地金溶解操作時期の地金溶解用酸素ガス中の純酸素流量の５０％以下に制限する。地金落下発生防止上、一層の安定性を要する場合には、地金溶解用酸素ガス中の純酸素流量の２０％以下に制限する。
【００３１】
（４）地金溶解用酸素の噴射方向については、ランスの長手方向軸心線１０に対する角度θが、４０〜９０°の角度をなして下向き乃至水平方向にすると、上述した地金溶解・除去の作用・効果が大きいこともわかった。
【００３２】
（５）本発明者らは、引き続き種々検討の結果、炉口に付着する地金の生成要因について以下の知見を得、それを基に開発した炉口地金付着を抑制する転炉吹錬方法を実施する。
【００３３】
（１）図４及び５において前述した通り、炉口地金は、吹錬初期のダスト発生量が多い時期にその付着形成速度が早い。更に調査をした結果、吹錬の比較的初期のダスト発生量は、図６及び図７に示すように溶銑中Ｓｉ濃度と前ヒートからの炉内残留スラグ量の影響が大きい。即ち、転炉装入溶銑中のＳｉ濃度が高くなるにつれて吹錬の比較的初期に発生するダスト量は多くなり、Ｓｉ濃度が０．１５質量 %以下なら吹錬の比較的初期ダスト発生量は少なく抑えられ、また、前ヒートからの炉内スラグ残留量が、１０kg/t-steel以上あると、吹錬の比較的初期に発生するダスト量は少なく抑えられる。
【００３４】
以上の現象は次のように考察される。Ｓｉは溶銑中炭素よりも酸化されやすく、脱炭吹錬の初期は脱珪素反応が優先的に起こる。この時溶銑の自由表面近傍は稠密であり、酸素ガスの衝突又は通過により非常にダスト（スプラッシュ）が発生しやすい状態になっていると考えられる。一方、脱炭反応が活発な時期に移行すると溶銑または溶鋼の自由表面近傍は脱炭反応によって生じたＣＯガスが存在し泡状となってダスト（スプラッシュ）が発生しにくい状態になると考えられる。
【００３５】
炉内残留スラグは、前ヒートの脱炭吹錬過程で一度溶融したスラグであるから、脱炭吹錬の比較的初期においても速やかに溶解する。従って、初期に速やかに溶銑の自由表面を覆い、ダストの発生を抑制できると考えられる。
【００３６】
以上により、溶銑Ｓｉ濃度を０．１５質量 %以下とし、前ヒートの炉内スラグを１０kg/t-steel以上当該ヒートの炉内に残留させて吹錬を開始することにより、炉口地金付着を抑制した。
【００３７】
▲２▼従来吹錬の炉口付着地金を採取して詳細に検討したところ、付着地金は鉄とスラグとの小粒が混合した状態であることが判明した。この状態で炉口に付着すると相互に絡み合って強固に固着してしまう。炉内に存在するスラグ量と吹錬の比較的初期のダスト発生速度との関係を調べた結果、図８に示すように、炉内に存在するスラグ量が少ない場合（約３０kg/t-steel以下のとき）に、初期のダスト発生速度が小さいという結果を得た。この結果と、図５の初期のダスト発生速度が小さい方が炉口地金除去頻度が減るという結果とを組み合わせると、吹錬中に炉内に存在するスラグ量が少なく３０kg/t-steel以下のときに、一定ヒート数当たりの炉口地金除去を要する回数が少なくて良いとの結果が得られる。
ただし、スラグ量が過度に少ない場合は溶鉄のカバーとなるものが存在せず溶鉄飛散につながる。これは、上記図７において、前ヒートからのスラグ残留量が１０kg/t-steel以上あると、吹錬の比較的初期に発生するダスト量が少なく、従って、炉口地金付着量が少なくなることからわかる。
以上により、吹錬中の炉内スラグを３０kg/t-steel以下とすることにより炉口地金付着を抑制した。
【００３８】
▲３▼前述した通り、炉口付着地金の実態は、鉄とスラグとの小粒が混合した状態で、相互に絡み合って強固に固着・成長し、凝固したものであることがわかった。このような付着地金の溶解においては、付着地金のスラグ成分部分が溶融しにくい。従って、付着地金のスラグ成分部分の比率を小さくすることが望ましい。これに対しては、上記▲１▼及び▲２▼項の説明から、第一は、吹錬中の炉内スラグ量を必要且つ最小限にすること、即ち、理想的には１０ないし２０kg/t-steelに調整することである。一方、スラグは転炉精錬反応中、脱Ｐ反応の促進に不可欠である。従って、転炉装入鉄原料中のＰ濃度を、素鋼目標Ｐ濃度以下に、従って成品仕様のＰ濃度以下に予め調整しておけば、生成スラグ量を少なくしてもよい。
上記Ｐ濃度低減の手段として、素鋼目標Ｐ濃度以下に脱Ｐ処理された溶銑を主な鉄源とするのが、転炉操業やコスト上から望ましい。また、このようにすることにより、付着地金は溶解し易くなり、地金の広範囲にわたり均一に溶解・除去され、また下地耐火物の損傷も一層抑制される。
【００３９】
【実施例】
この発明を実施例により更に詳細に説明する。
試験方法は、３００ｔ転炉に溶銑３１０ｔ及びスクラップ１０ｔ、並びに造滓材を所定量装入し、上吹きランスで脱炭精錬をした。用いた設備は図１に示したものに準じる。上吹きランスとして、下端に吹錬用酸素ノズルを配し、下端から同一高さの外周面に地金溶解用酸素ノズルを等間隔に８孔を、下端から２０００ｍｍ高さ毎に２段配した８孔×２段型のものを用いた。そして、ノズルの形状及び諸元、並びにノズルの取付け角を種々変えた。また、地金溶解用酸素ガス中の純酸素流量、及びノズル出口前圧力を各種に設定した。
【００４０】
試験は、本発明の範囲内の条件により連続３０ヒートの精錬を行ない、次いで、本発明の範囲外の条件により連続３０ヒートの精錬を行なった。
表１に、本発明の範囲内の試験（実施例）、及び範囲外の試験（比較例）の
試験条件を示す。
【００４１】
【表１】

【００４２】
実施例の連続３０ヒートの前後、及び比較例の連続３０ヒートの前後に、炉口及び炉内側壁に付着していた地金の位置と量との測定、及び、炉内耐火物の損耗状態を測定し、連続ヒート前後の測定値を比較して、それぞれの地金溶解指数、及び耐火物溶損指数を求めた。表１にこれら指数を併記した。
【００４３】
上記試験結果より、実施例では、耐火物の溶損を抑えつつ地金の溶解が促進され、これに対して、比較例では、地金の付着堆積は防止されたが、耐火物の損傷が進んだ。
【００４４】
【発明の効果】
以上述べたように、この発明によれば、転炉型精錬炉における生産性を阻害することなく、炉口耐火物の損傷を抑制しつつ、効率的に炉口地金の付着を抑制する方法を提供することができ、工業上有用な効果がもたらされる。
【図面の簡単な説明】
【図１】この発明の方法を実施するために用いる設備例の概念図である。
【図２】吹錬用酸素の流量ａと炉口地金溶解用酸素ガス中の純酸素流量ｂとの比率ｂ／ａと、炉口地金の溶解速度との関係を示すグラフである。
【図３】吹錬用酸素の流量ａと、炉口地金溶解用酸素ガス中の純酸素流量ｂとの比率ｂ／ａと、炉口耐火物の溶損速度との関係を示すグラフである。
【図４】脱炭吹錬１ヒート中におけるダスト発生量の推移を示すグラフである。
【図５】初期ダスト発生量と炉口地金除去頻度の関係を示すグラフである。
【図６】脱炭吹錬初期３分のダスト発生量におよぼす溶銑Ｓｉ濃度の影響を示すグラフである。
【図７】初期ダスト発生速度におよぼす前ヒートからの炉内残留スラグ量の影響を示すグラフである。
【図８】初期ダスト発生速度におよぼす吹錬中の炉内スラグ量の影響を示すグラフである。
【符号の説明】
１溶銑
２造滓材
３転炉
４炉口
５吹錬用ランス
６吹錬用酸素ノズル
７炉口地金溶解用ノズル
８炉口地金
８’ 炉内側壁地金
９炉口耐火物
１０軸心線[0001]
BACKGROUND OF THE INVENTION
In the converter type refining furnace, the raw metal charging to the furnace mouth and the inner wall of the furnace is performed in order to smoothly perform the raw material charging operation into the furnace and to smoothly maintain the furnace mouth device and the inner wall of the furnace. The present invention relates to a converter blowing method for suppressing adhesion.
[0002]
[Prior art]
In converter refining, some of the molten steel and slag scattered by spitting and slopping generated during blowing are attached to the furnace mouth and the inner wall of the furnace as metal. The adhered metal grows as the heat continues, and when its size exceeds a certain limit, it not only hinders hot metal and scrap charging, but also operates by dropping into the bath during blowing and melting. Cause a major obstacle. Therefore, it is necessary to remove the above adhering metal before it becomes larger than the size that hinders operation.
[0003]
As a traditional method of removing the furnace mouth metal, there is a method of physically removing the scrap shout against the furnace mouth metal part. However, since this method must be carried out when the converter is not blown, the non-steel time is increased and the converter productivity is significantly hindered. In addition, since the scrap shout directly hits the furnace opening metal part, there is a risk of dropping the furnace opening brick due to the impact.
[0004]
On the other hand, a method has been proposed in which the exhaust gas generated during blowing is secondarily burned without hindering productivity in the converter to dissolve and remove the furnace port and the inner wall of the furnace inner wall.
For example, Japanese Patent Application Laid-Open No. 6-248323 is attached downward at an angle in the range of θ = 25-40 ° with respect to the lance shaft for blowing provided on the side wall of the main lance for blowing during blowing. A method in which oxygen for secondary combustion is blown from the oxygen supply nozzle for secondary combustion toward the molten metal surface, the converter exhaust gas is burned in the furnace, and the bare metal adhering to the furnace port is dissolved and removed by the generated heat (preceding) Technique 1) is disclosed.
[0005]
Japanese Patent Laid-Open No. 61-139616 discloses that a converter smelting nozzle is provided with a blowing lance provided with a nozzle for melting and a nozzle for melting the furnace mouth during refining of the converter. The method (prior art 2) which melts and removes a furnace neck ingot by injecting air toward a furnace furnace mouth is disclosed.
[0006]
[Problems to be solved by the invention]
The inventors of the present invention have developed a technique for melting and removing the converter furnace mouth and the inner wall of the furnace wall to prevent damage to the refractory during melting and removal of the bare metal as much as possible and to efficiently remove the bare metal. On the premise of ensuring productivity, the task was to solve the following problems.
[0007]
Molten metal attached to the furnace mouth does not interfere with the furnace charging work of hot metal and scrap, and the molten steel temperature at the end of blowing due to detachment / falling of the molten metal during blowing and molten flow In order to prevent the occurrence of abnormalities in components and components, and to prevent the melting and melting of the furnace refractory material, while suppressing the adhesion and growth of the metal, to improve the maintenance and maintenance of the furnace mouth device and the inner wall of the furnace In addition, it is necessary to manage the adhesion state of the bullion well. For this purpose, the adhering metal must be dissolved and removed by supplying oxygen for melting the furnace metal to the metal adhesion position accurately and supplying an appropriate amount of oxygen gas at an appropriate pressure to that position. That is, it is necessary to control the supply of the oxygen for melting the furnace mouth metal so that the attached metal can be dissolved and removed accurately.
[0008]
According to the above viewpoint, the prior art has the following problems.
In Prior Art 1, since the injection direction of the secondary combustion oxygen is relatively close to the vertical downward direction, the CO gas is subjected to secondary combustion while being caught in the exhaust gas in the furnace, and most of the secondary combustion is performed from the inside of the furnace to the furnace port. Is consumed. Accordingly, the high-temperature gas of 2000 ° C. or higher due to the high heat generated at that time is liable to cause significant damage not only to the melting of the converter furnace metal but also to the converter furnace metal and the furnace refractory.
[0009]
According to the prior art 2, since air is used as the oxygen source for melting the furnace opening metal, the injection amount is increased as compared with the case of injecting oxygen, and the metal melting of the furnace opening refractory can be prevented from being melted. . However, since the oxygen concentration is low in air, it takes time to dissolve the furnace opening metal, which is inefficient.
[0010]
By the way, in order to control the refractory existing under the adhering bullion, that is, the base refractory, while suppressing the damage of the refractory that adheres over a wide area uniformly and efficiently, it is blown within one heat. It is necessary to appropriately change the flow rate of pure oxygen in the metal gas for dissolving metal from time to time. The oxygen gas flow supplied from the metal melting nozzle changes greatly depending on the gas flow in the furnace. Here, the state of the gas flow in the furnace changes depending on the component composition of the bath and the oxygen flow rate for blowing. Therefore, the flow rate of pure oxygen in the metal gas for melting metal should be determined appropriately according to the flow rate of oxygen for blowing at that time. However, there is no disclosure of such technical matters in the prior art.
[0011]
As described above, the prior arts have respective problems, and the supply of oxygen for dissolving the metal, which is the center of the problem to be solved by the present invention, cannot be controlled well.
Therefore, the object of the present invention is to ensure the productivity of molten steel in the converter, and to prevent the refractory on the furnace opening and the inner wall of the furnace from being melted and to manage the adhesion state of the metal well. It is to provide a smelting method.
[0012]
[Means for Solving the Problems]
The present inventors have conducted research from the above-mentioned viewpoints and obtained the following knowledge.
1. First, a test was conducted to determine at which stage of blowing the ingots adhere to the furnace port and the inner wall of the furnace. As a result, it was found that the metal adhesion time was attached in large amounts relatively early in the blowing process. Then, the idea that the melting operation of the adhesion metal should be carried out at least including the initial stage of blowing.
[0013]
2. Next, it is necessary to avoid the adverse effects of the melting operation of the adhered metal. That is, at the end of blowing, if the metal attached to the furnace mouth or the inner wall of the furnace is dissolved and removed by the oxygen gas for dissolving the metal, the molten metal flows into the bath or the metal lumps fall. As a result, the rise of impurity components in the bath and the decrease in bath temperature occur, the controllability of the component composition and molten steel temperature at the end of the blowing process deteriorates, the target component composition deviates and the target temperature deviates, resulting in stable operation. Adverse effects such as a decrease in productivity, a decrease in quality, or a decrease in production yield are likely to occur. Therefore, in order to prevent the temperature and component composition of the molten steel from deviating from the target at the end of blowing, at least after the temperature and component analysis sample collection at the end of blowing and after the so-called sublance measurement, It is desirable not to supply oxygen for dissolution. During this time, it is necessary to keep the purge gas flowing from the nozzle in order to prevent the metal melting nozzle from clogging.
Therefore, when melting and removing the ingot from the furnace port and the inner wall of the furnace during converter blowing, this operation should not be performed at the end of the blowing.
[0014]
3. In order to dissolve the adherent metal as uniformly as possible over a wide area and not to damage the refractory underneath the metal, oxygen gas for dissolving the metal is supplied according to the state of gas flow in the furnace. Has been found to be effective, that is, it is effective to supply the oxygen gas for dissolving a metal in accordance with the flow rate of the oxygen gas for blowing.
The present invention has been made on the basis of the above matters and is as follows.
[0015]
The invention according to claim 1 is a converter type refining furnace in which hot metal is used as a main iron source and refining is performed by top blowing or top bottom blowing oxygen. A blowing nozzle is provided at the lower end, and a metal melting nozzle is provided at the outer periphery. A lance that is provided on the surface and can supply oxygen gas or purge gas independently from the blowing oxygen gas from the metal melting nozzle is used for the metal inlet and / or the inner wall of the furnace. When suppressing the adhesion , the blowing period is divided into the first blowing stage and the second blowing stage, and in the first blowing stage, oxygen gas is supplied from the metal melting nozzle to the furnace port and / or Melting and removing the metal adhering to the inner wall of the furnace, and then, in the late stage of blowing, flowing a purge gas or this purge gas and oxygen gas at a predetermined flow rate or less in terms of pure oxygen from the nozzle for melting the metal, Blowing while preventing clogging of the metal melting nozzle That the blowing method, the boundary point between the blowing year and late, the time in the range of 50% to 95% from the start of blowing blowing total expected time, for bullion dissolved to flow on the blowing year The pure oxygen flow rate in the oxygen gas is within the range of 3 to 10% of the oxygen gas flow rate for blowing, and the pure oxygen flow rate in the oxygen gas that flows from the metal melting nozzle together with the purge gas in the late stage of blowing, It is characterized in that it is limited to 50% or less of the pure oxygen flow rate in the oxygen gas for melting metal in the first stage of blowing.
[0016]
The invention according to claim 2 is the blowing method according to claim 1, wherein an angle formed between an injection direction of oxygen injected from the metal melting nozzle and a longitudinal axis of the lance is 40 to 90 °. And is characterized by being downward or horizontal .
[0017]
In a converter type refining furnace in which refining is performed by top blowing or top bottom blowing oxygen using hot metal as a main iron source, the Si concentration of the hot metal charged into the converter type refining furnace is 0. is 15 wt% or less, the slag of the previous heat is remaining in the 10 kg / t-steel or furnace, this furnace slag amount of heat not more than 30 kg / t-steel, and, according to claim 1 or 2, wherein It is characterized by blowing under any of the conditions .
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described.
FIG. 1 is a conceptual diagram of an example of equipment used for carrying out the method of the present invention.
[0021]
A lance 5 is inserted into the furnace through the furnace port 4 from above the converter 3 in which the hot metal 1 and the ironmaking material 2 are charged. The lance 5 is provided with a blown oxygen nozzle 6 at the lower end and a metal melting nozzle 7 at a predetermined position above the lower end. The gas injection direction from the metal melting nozzle 7 is downward or horizontal within an angle of 40 to 90 ° with the longitudinal axis of the lance set vertically. As a result, the bullion adhering to the furnace port 4 and its constricted portion (referred to as “furnace bullion” unless otherwise specified) and the bullion adhering to the inner wall of the furnace (unless otherwise specified) All of the “metal” is dissolved and removed. The structure of the lance 5 includes an oxygen supply pipe for supplying oxygen gas to the blowing nozzle 6, an oxygen / purge gas supply pipe for supplying oxygen gas and / or purge gas to the metal melting nozzle 7, and cooling of the lance. It has a quadruple structure of water supply pipe and drain pipe. In this way, the supply path of the metal for melting the metal can be controlled independently of the supply path of the blowing oxygen.
[0022]
(1) Using the above equipment, oxygen gas at a predetermined flow rate a (Nm ³ / min) is jetted from the blowing nozzle 6 to blow molten iron. On the other hand, oxygen gas at a predetermined flow rate b (Nm ³ / min) is jetted from the metal melting nozzle 7, and the metal 8 attached to the furnace port 4 and its throttle part, and the metal attached to the inner wall of the furnace. Dissolve 8 'and remove. However, what is important here is that when melting and removing the bullion 8 and 8 ', the refractory under the bullion should not be damaged, and usually on almost the entire inner surface of the narrowed part of the furnace opening. This is to uniformly dissolve and remove the metal that has adhered over the surface. The pure oxygen flow rate in the oxygen gas for melting metal for realizing this was determined with respect to the flow rate of the oxygen gas for blowing.
[0023]
A 300t / ch upper bottom blowing converter was used, and as a lance, a nozzle for smelting consisting of a 6-hole Laval nozzle was provided at the lower end, and the metal melting nozzle was placed in two stages at a predetermined height from the lower end of the lance. 10 nozzles were provided along the outer periphery of the lance, and those having a nozzle diameter of 8 mm were used. The angle θ (see FIG. 1) formed between the injection direction of the metal melting oxygen and the axial center line of the lance was 90 °, that is, oxygen was injected in the horizontal direction. As the flow rate a of blowing oxygen was performed at two levels of 170~500Nm ³ / min, and 700 to 1000 nm ³ / min.
[0024]
The dissolution test of the bullion was conducted when the amount of adhesion of the furnace bullion reached the standard value. The ratio (b / a) × 100 (%) of the flow rate a of blowing oxygen and the flow rate b of dissolved metal oxygen was changed to various values within the range of 0 to 70%. And the melting rate of the furnace neck metal was calculated | required from the expansion rate of the diameter of a furnace port accompanying melt | dissolution of a furnace mouth metal, and this was represented with the melt | dissolution rate index | exponent. The larger this index is, the faster the dissolution rate is, which indicates that it is desirable for metal removal. In addition, the melting rate of the furnace refractory was measured and expressed as an index. The smaller this index is, the lower the melting rate and the better.
[0025]
FIG. 2 shows the relationship between b / a and the melting rate of the furnace port metal, and FIG. 3 shows the relationship between b / a and the melting rate of the furnace port refractory. As can be seen from FIGS. 2 and 3, when b / a is in the range of 1 to 50%, the furnace mouth metal can be quickly dissolved, and the amount of erosion loss of the furnace mouth refractory is small. . In particular, good results were obtained when b / a was 3 to 10%.
[0026]
From the above, the pure oxygen flow rate b (Nm ³ / min) in the metal gas for melting metal is supplied within the range of 3 to 10% of the flow rate a (Nm ³ / min) of the oxygen gas for blowing. It is better to perform the target melting of the bullion.
[0027]
(2) Next, the 1-heat blowing period is divided into a first period and a second period, and in the first period, the metal melting operation is performed according to the supply condition of the above-mentioned metal melting oxygen. The reason for this is that the bullion is dissolved efficiently by at least including the period when the adhesion rate of the bullion is high, and by doing so, It is also effective in preventing the occurrence of a situation in which a metal removal operation for securing the raw material charging work for the next heat is not required at the time of non-blowing after the heat formed in large quantities. This is because the period when the metal adhesion speed to the furnace mouth is large is a relatively early stage of blowing.
[0028]
FIG. 4 shows the relationship between the elapsed time of decarburization blowing 1 heat and the amount of dust generated. According to this, the amount of dust generated is large in the early stage of blowing. FIG. 5 shows the relationship between the amount of dust generated at the initial stage of blowing and the number of times the furnace opening metal was removed by operation at a constant heat number in the conventional blowing method. According to this, as the initial dust generation amount increases, the frequency of removal of the furnace neck metal increases. Therefore, it can be seen from FIGS. 4 and 5 that the furnace neck metal has a high adhesion formation rate when the amount of dust generated in the initial stage of blowing is large.
[0029]
It is important that the time for the bullion melting operation includes the time when the bullion formation speed is high, so it is usually from the beginning of blowing to the time before the so-called sublance measurement at the end of blowing. It doesn't matter. In addition, if the heat is in a state where a large amount of bullion is attached, the melting of the bullion can be continued until about 5% of the total scheduled blowing time before the end of the smelting schedule, If a small amount of bullion is attached, melting of the bullion may be terminated in the middle of blowing.
[0030]
Thus, since it is not always advantageous to determine the end point of the melting time of the bullion, the boundary time point between the first half and the second half is, for example, 50% of the total scheduled time from the start of blowing. A certain time point within the range of -95% may be set. Moreover, what is necessary is just to set it as a certain time point in the range of 70 to 95% of the total blowing time from the start of blowing. Which one is selected depends on the individual operation in consideration of equipment and operating conditions, including the status of metal adhesion in the converter for the entire operation, the grade of steel to be refined, the product specifications of the molten steel, the wear status of the furnace refractory, etc. It is better to decide on.
(3) Next, in the latter stage of blowing without performing the metal melting operation, a purge gas is allowed to flow from the metal melting nozzle. In this case, the purpose is to prevent clogging of the nozzle. Therefore, it is usually assumed that a gas pressure of about 2 atm (absolute pressure) or slightly higher than that must be maintained at the nozzle outlet, and an appropriate gas flow rate is secured. The flow rate of the purge gas may be determined empirically. However, as the purge gas type, an inert gas such as argon gas should be used at the end of blowing when the low nitrogen steel type is melted. Nitrogen gas cannot be used with low nitrogen steel grades because it cannot be expected to have a denitrifying effect after the end of blowing, but this is not the case when high nitrogen steel grades are melted. Further, the purge gas has a relationship of using the metal melting nozzle 7, and if the oxygen gas is limited to a predetermined value or less, it may flow together with the purge gas. In general, the predetermined value is limited to 50% or less of the pure oxygen flow rate in the metal gas for dissolving the metal at the time of the metal melting operation from the viewpoint of preventing the molten metal from lump falling. When further stability is required to prevent the falling of the bullion, it is limited to 20% or less of the pure oxygen flow rate in the oxygen gas for melting the bullion.
[0031]
(4) Regarding the injection direction of the oxygen for melting the bullion, when the angle θ with respect to the longitudinal axial center line 10 of the lance is 40 to 90 ° downward or horizontally, the above-described bullion dissolution / removal It was also found that the action and effect of
[0032]
(5) As a result of various investigations, the present inventors have obtained the following knowledge about the formation factors of the ingots attached to the furnace mouth, and the converter blowing that suppresses the adhesion of the furnace mouth ingots developed based on the following knowledge. Implement the method.
[0033]
(1) As described above with reference to FIGS. 4 and 5, the furnace neck metal has a high adhesion formation rate at a time when the amount of dust generated in the initial stage of blowing is large. As a result of further investigation, as shown in FIGS. 6 and 7, the amount of dust generated in the relatively early stage of blowing is greatly affected by the Si concentration in the hot metal and the amount of residual slag in the furnace from the previous heat. That is, as the Si concentration in the molten iron in the converter increases, the amount of dust generated relatively early in the blowing increases, and if the Si concentration is 0.15 % by mass or less, the relatively initial amount of dust generated in the blowing is If the amount of residual slag in the furnace from the previous heat is 10 kg / t-steel or more, the amount of dust generated in the relatively early stage of blowing is reduced.
[0034]
The above phenomenon is considered as follows. Si is more easily oxidized than carbon in the hot metal, and the desiliconization reaction preferentially occurs in the initial stage of decarburization blowing. At this time, the vicinity of the free surface of the hot metal is dense, and it is considered that dust (splash) is very easily generated by collision or passage of oxygen gas. On the other hand, when the decarburization reaction is active, it is considered that CO gas generated by the decarburization reaction is present near the free surface of the hot metal or molten steel and becomes in a foam state so that dust (splash) is hardly generated.
[0035]
Since the residual slag in the furnace is slag once melted in the decarburization blowing process of the preheat, it dissolves quickly even in a relatively early stage of decarburization blowing. Therefore, it is considered that the free surface of the hot metal can be covered quickly and the generation of dust can be suppressed early.
[0036]
As described above, the molten iron Si concentration is set to 0.15 % by mass or less, and the furnace slag adheres to the furnace mouth by leaving the slag in the furnace of the previous heat at least 10 kg / t-steel in the furnace of the heat to start blowing. Was suppressed.
[0037]
(2) Collecting the ingot from the conventional blow smelting furnace and examining it in detail, it was found that the attached ingot was a mixture of small particles of iron and slag. If it adheres to the furnace port in this state, they will be entangled with each other and firmly fixed. As a result of investigating the relationship between the amount of slag present in the furnace and the relatively early dust generation rate of blowing, as shown in FIG. 8, when the amount of slag present in the furnace is small (about 30 kg / t-steel The following results were obtained: the initial dust generation rate was low. Combining this result with the result that the lower dust generation rate in the initial stage of FIG. 5 reduces the frequency of removal of the metal in the furnace mouth, the amount of slag present in the furnace during blowing is less and less than 30 kg / t-steel. In this case, it is possible to obtain a result that the number of times required to remove the furnace neck metal per certain number of heats may be small.
However, when the amount of slag is excessively small, there is no cover for molten iron, which leads to molten iron scattering. In FIG. 7 above, if the residual amount of slag from the previous heat is 10 kg / t-steel or more, the amount of dust generated in the relatively early stage of blowing is small, and therefore the amount of adhesion of the furnace mouth metal becomes small. I understand.
As described above, the furnace slag during blowing was controlled to be 30 kg / t-steel or less, thereby suppressing the adhesion of the furnace mouth metal.
[0038]
(3) As described above, it has been found that the actual state of the ingot attached to the furnace mouth is a mixture of small particles of iron and slag that are intertwined with each other, firmly fixed and grown, and solidified. In the dissolution of such an attached metal, the slag component part of the attached metal is difficult to melt. Therefore, it is desirable to reduce the ratio of the slag component portion of the adhered metal. On the other hand, from the description of the above items (1) and (2), the first is to reduce the amount of slag in the furnace during blowing to the minimum and necessary, that is, ideally 10 to 20 kg / It is to adjust to t-steel. On the other hand, slag is indispensable for promoting the de-P reaction during the converter refining reaction. Accordingly, the amount of generated slag may be reduced if the P concentration in the raw material charged in the converter is previously adjusted to be equal to or lower than the target P concentration of the steel, and thus lower than the P concentration of the product specification.
As a means for reducing the P concentration, it is desirable from the viewpoint of converter operation and cost to use hot metal, which has been de-P-treated to a target steel P concentration or less, as a main iron source. Moreover, by doing in this way, an adhesion | attachment metal becomes easy to melt | dissolve, it melt | dissolves and removes uniformly over a wide range of metal, and damage to a base refractory is further suppressed.
[0039]
【Example】
The present invention will be described in more detail with reference to examples.
In the test method, a predetermined amount of hot metal 310t, scrap 10t, and ironmaking material were charged into a 300t converter, and decarburization refining was performed with an upper blow lance. The equipment used is similar to that shown in FIG. As an upper blowing lance, an oxygen nozzle for blowing was arranged at the lower end, 8 holes were arranged at equal intervals on the outer peripheral surface of the same height from the lower end, and two stages were arranged every 2000 mm from the lower end. An 8-hole x 2-stage type was used. And the shape and specifications of the nozzle and the mounting angle of the nozzle were variously changed. Moreover, the pure oxygen flow rate in the oxygen gas for dissolving the metal bar and the pressure before the nozzle outlet were variously set.
[0040]
In the test, refining for 30 consecutive heats was performed under conditions within the scope of the present invention, and then refining for 30 consecutive heats was performed under conditions outside the scope of the present invention.
Table 1 shows test conditions for tests within the scope of the present invention (Examples) and tests outside the scope (Comparative Examples).
[0041]
[Table 1]

[0042]
Before and after the continuous 30 heat of the example, and before and after the continuous 30 heat of the comparative example, measurement of the position and amount of the metal that has adhered to the furnace mouth and the inner wall of the furnace, and the wear state of the refractory in the furnace Were measured, and the measured values before and after the continuous heat were compared to determine the respective melt refractory index and refractory melt index. Table 1 also shows these indices.
[0043]
From the above test results, in the example, the dissolution of the bullion was promoted while suppressing the refractory melting, whereas in the comparative example, the adhesion and deposition of the bullion was prevented, but the refractory was damaged. Progressed.
[0044]
【The invention's effect】
As described above, according to the present invention, the method of efficiently suppressing the adhesion of the furnace mouth metal while suppressing the damage to the furnace mouth refractory without inhibiting the productivity in the converter type refining furnace. This can provide an industrially useful effect.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an example of equipment used for carrying out the method of the present invention.
FIG. 2 is a graph showing the relationship between the ratio b / a of the flow rate a of blowing oxygen and the pure oxygen flow rate b in the oxygen gas for melting the furnace mouth metal, and the melting rate of the furnace mouth metal.
FIG. 3 is a graph showing the relationship between the ratio b / a between the flow rate a of oxygen for blowing and the pure oxygen flow rate b in the oxygen gas for melting the furnace mouth metal, and the melting rate of the furnace mouth refractory. is there.
FIG. 4 is a graph showing the transition of the amount of dust generated during 1 heat of decarburization blowing.
FIG. 5 is a graph showing the relationship between the amount of initial dust generation and the frequency of removal of the furnace mouth metal.
FIG. 6 is a graph showing the influence of hot metal Si concentration on the amount of dust generated in the first 3 minutes of decarburization blowing.
FIG. 7 is a graph showing the influence of the amount of residual slag in the furnace from the previous heat on the initial dust generation rate.
FIG. 8 is a graph showing the influence of the amount of slag in the furnace during blowing on the initial dust generation rate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hot metal 2 Smelting material 3 Converter 4 Furnace 5 Blasting lance 6 Blowing oxygen nozzle 7 Furnace metal melting nozzle 8 Furnace metal 8 'Furnace inner wall 9 Furnace refractory 10 shaft Core wire

Claims

In a converter type smelting furnace in which hot metal is used as the main iron source and refining with top blowing or top bottom blowing oxygen, a blowing nozzle is provided at the lower end, a metal melting nozzle is provided on the outer peripheral surface, and the metal from dissolved nozzle using a lance that can be supplied in controlled independently of the blowing oxygen gas and oxygen gas or purge gas, when suppressing the base metal adhere to the throat and / or the furnace side wall In addition, the blowing period is divided into the first stage of blowing and the latter stage of blowing, and in the first stage of blowing, oxygen gas is supplied from the metal melting nozzle to adhere to the furnace outlet and / or the inner wall of the furnace. Next, in the latter stage of blowing, purge metal or a purge gas and oxygen gas having a predetermined flow rate or less in terms of pure oxygen are allowed to flow from the metal melting nozzle, and the metal of the metal melting nozzle is discharged. In the blowing method of blowing while preventing clogging,
The boundary time point between the first and second stages of blowing is defined as a time point within the range of 50 to 95% of the total scheduled time of blowing from the start of blowing, and pure oxygen in the oxygen gas for melting metal flowing in the first stage of blowing The flow rate is set within the range of 3 to 10% of the flow rate of oxygen gas for blowing, and the pure oxygen flow rate in the oxygen gas flowing from the metal melting nozzle together with the purge gas in the late stage of blowing is passed in the early stage of blowing. A method for suppressing bullion adhesion in a converter-type smelting furnace , which is limited to 50% or less of the pure oxygen flow rate in the dissolved oxygen gas for bullion .

2. The blowing method according to claim 1, wherein the angle formed by the longitudinal axis of the lance with respect to the injection direction of oxygen injected from the metal melting nozzle is within a range of 40 to 90 °, and A method for suppressing bullion adhesion in a converter-type smelting furnace , characterized in that it is downward or horizontal .

In the converter type smelting furnace in which hot metal is the main iron source and refining with top blowing or top bottom blowing oxygen, the Si concentration of the hot metal charged into the converter type smelting furnace is 0.15 % by mass or less, Heat slag of 10 kg / t-steel or more is left in the furnace, and the amount of heat slag in the furnace is set to 30 kg / t-steel or less this time , and blow smelting is performed according to any one of claims 1 and 2. A smelting method for suppressing metal adhesion in a converter-type smelting furnace.