【0001】
【産業上の利用分野】
本発明は、ベルレス高炉内における装入原料(コークスと鉱石)の積層状態を鉱石装入段階で調整することによって中心ガス流を確保するベルレス高炉への原料装入方法に関するものである。
【0002】
【従来の技術】
一般にベル式高炉では炉頂部の大ベルとムーバブルアーマプレートを用い、またベルレス式高炉では旋回シュートを用いてコークスと塊鉱石、焼結鉱、ペレット等の含鉄鉱石(以下、単に鉱石という)とが交互に装入され、これによって炉内にコークス層と鉱石層とが交互に堆積される。このようにして炉内に堆積されたコークス層と鉱石層とは炉内を徐々に降下し、炉底部の羽口から吹き込まれる熱風と炉内に装入したコークスとの反応によって生じる高温のCOガスにより鉱石が加熱、還元され、軟化融着帯を形成したのち、溶滴はコークス層の間を通過し、炉底部に溶銑が溜まる。
【0003】
このような高炉操業では、炉内半径方向のガス流分布を適正に制御し、炉内鉱石の還元、溶解を安定して行う必要がある。炉内半径方向のガス流分布を制御するため炉内半径方向のコークス(Coke)と鉱石(Ore)との重量分布や粒径分布等を制御する方法が採用されている。とくに、炉内にコークス層と鉱石層とを交互に堆積するに際し、炉中心部にほぼ連続した炉芯コークス層を形成し、高炉内のガス流分布を中心流化することによって融着帯を逆V字形に維持し、高炉の炉況安定化を図ることが知られている。
【0004】
また特開昭55−28308 号公報には、焼結鉱およびコークス等の装入原料をそれぞれ所定の粒径を有する複数の種別に分割したバッチとし前記装入原料の粒度種別と装入量を選択し、炉周方向の均等分布装入もしくは局部選択装入を行う高炉の操業方法が開示されている。同公報、48頁の実施例1には分割した鉱石のうち粗粒部分のバッチ(もしくは中間粒)を炉断面に均等に装入すると共に、炉周辺近傍に(中間粒もしくは)細粒部分のバッチを装入することにより周辺ガス流を抑制する場合について説明してある。
【0005】
このように、粗粒鉱石バッチを炉断面に均等的に装入すると共に炉周辺近傍に細粒部分のバッチを装入する場合には、従来は粗粒鉱石バッチ→細粒鉱石バッチの順序で装入していた。すなわち図4(a)に示すように、まずコークス上に小粒焼結鉱等の小塊鉱石を含まない粗粒鉱石バッチを、たとえばベル型高炉では大ベルから落下する鉱石をムーバブルアーマプレートを調整しながら、またベルレス高炉では旋回シュートの傾動角を調整して炉断面に均等的に装入した後、小塊焼結鉱等の細粒鉱石バッチを炉壁近傍に集中装入していた。
【0006】
ところで高炉操業にとって望ましい鉱石の粒度調整法は粒度範囲を増すことによって炉内通気性の向上と円滑な装入物降下を保証することであり、そのためには下限粒度を上げるのが効果的である。しかし、たとえば焼結鉱では下限粒度付近の重量割合が比較的高いので、現状以上に下限粒度を上げると返鉱が量的に増加し、焼結鉱の塊歩留が低下する。その結果、高炉操業が改善されても、他方で焼結機の生産性が低下し、製造コストが上昇するばかりでなく塊粉の量的均衡を乱すこととなり不利となる。
【0007】
【発明が解決しようとする課題】
このため、前述のようにして1チャージで装入する鉱石を粗粒鉱石バッチと細粒鉱石バッチに分割し、粗粒鉱石バッチを炉内に均等的に装入したのち、細粒鉱石バッチを炉周辺近傍に局部的に集中装入するに際し、 炉内に1チャージで装入する鉱石に対する小塊鉱石の配合比を増加していくと前述図4の(a)に示すようにコークス上にほぼ均等に粗粒鉱石を装入したのち、炉周辺近傍に局部的に集中装入する細粒鉱石バッチ(ここでは小塊焼結鉱の配合比が16重量%)が、堆積の許容限度に達し、 炉中心側に崩れ込みを始め、粗粒鉱石を越えて炉中心部まで細粒鉱石で被ってしまうようになる。
【0008】
このように炉内装入物の中心部の表面までが細粒鉱石により被覆されてしまうと、炉内の通気抵抗の上昇を招き、とくに炉中心部の通気性を確保することができなくなる。このため図4の(b)に示すように炉頂固定ゾンデによって測定した炉直径方向の温度分布は炉中心よりも炉周辺が高くなり、炉内に形成される融着帯を逆V字形にすることができなくなって正常な高炉操業を行うことができなくなるという問題点があった。
【0009】
本発明は前記従来技術の問題点を解消し、ベルレス高炉の炉内に装入する1チャージ当りの鉱石に対する小塊鉱石の配合比を増加させても細粒鉱石バッチが炉中心方向に崩れ込むのを軽減することができるベルレス高炉への原料装入方法を提供することを目的とするものである。
【0010】
【問題を解決するための手段】
前記目的を達成するための請求項1記載の本発明は、ベルレス高炉に対してコークスと鉱石とを交互に装入するに当り、1チャージで装入する鉱石を粗粒鉱石バッチと小塊鉱石を含む細粒鉱石バッチとに分割し、分割した粗粒鉱石バッチを炉内に均等的装入を行い、細粒鉱石バッチを炉周辺近傍に局部的に集中装入を行うベルレス高炉への原料装入方法において、小塊鉱石の配合比が少ないときコークス層上に粗粒鉱石バッチを炉内に均等的装入を行ったのち、細粒鉱石バッチを炉周辺近傍に局部的に集中装入し、前記炉内に装入する1チャージ当りの鉱石のうち細粒鉱石バッチを、前記炉周辺近傍に局部的に集中装入した際に、炉中心側に崩れ込みを始める配合比まで小塊鉱石が増加した段階で、粗粒鉱石バッチと細粒鉱石バッチとの装入順序を入れ替え、細粒鉱石バッチをコークス装入後のコークス層上の炉周辺近傍に局部的に集中装入し炉中心側に崩れ込む細粒鉱石をコークス層上に止めたのち、粗粒鉱石バッチを炉内に均等的装入を行うことを特徴とするベルレス高炉への原料装入方法である。
【0011】
請求項2記載の本発明は、前記炉内に装入する1チャージ当りの鉱石に対する小塊鉱石の配合比が10重量%以上となった段階で粗粒鉱石バッチと細粒鉱石バッチとの装入順序を入れ替え、細粒鉱石バッチをコークス装入後のコークス層上の炉周辺近傍に局部的に集中装入し炉中心側に崩れ込む細粒鉱石をコークス層上に止めたのち、粗粒鉱石バッチを炉内に均等的装入を行うことを特徴とする請求項1記載のベルレス高炉への原料装入方法である。
【0012】
請求項3記載の本発明は、大塊鉱石または中塊鉱石に小塊鉱石を混合して細粒鉱石バッチとする場合に、前記細粒鉱石バッチ中の小塊鉱石の配合比が30重量%以上になった段階で粗粒鉱石バッチと細粒鉱石バッチとの装入順序を入れ替え、細粒鉱石バッチをコークス装入後のコークス層上の炉周辺近傍に局部的に集中装入し炉中心側に崩れ込む細粒鉱石をコークス層上に止めたのち、粗粒鉱石バッチを炉内に均等的装入を行うことを特徴とする請求項1または2記載のベルレス高炉への原料装入方法である。
【0013】
【作用】
本発明では、炉内に1チャージで装入する鉱石(細粒鉱石バッチ鉱石量+粗粒鉱石バッチ鉱石量)に対する小塊鉱石の配合比を増加する途中で、炉周辺近傍に集中装入した際に、1チャージで装入する鉱石の小塊鉱石の配合比を炉中心側に崩れ込みを始める10重量%以上の配合比まで増加させた段階で、鉱石の装入順序を入れ替え、細粒鉱石バッチ(たとえば大塊鉱石または中塊鉱石に小塊焼結鉱を混合して細粒鉱石バッチとしたもの)を炉周辺近傍に集中装入を行ったのち、粗粒鉱石バッチを炉内に均等的装入を行う。そのためこの装入順では細粒鉱石バッチ(ここでは小塊焼結鉱の配合比13重量%)が従来のように比較的辷り現象を生じ易い大塊鉱石上ではなく、図3の(a)に示すように辷り難いコークス上に装入されるため炉周辺近傍に集中装入した細粒鉱石が炉中心側に崩れ込みを生じるのを大幅に低減できる。その結果、細粒鉱石の崩れ込みによる炉内通気抵抗の上昇が見られなくなり、炉内での中心ガス流が確保されるので図3の(b)に示すように炉直径方向の温度分布は炉周辺近傍よりも炉中心側が高くなり正常なベルレス高炉操業を行うことができるようになる。
【0014】
ここで、細粒鉱石バッチとは、粒度が概ね1〜5mm範囲で平均粒度3mm程度の小塊焼結鉱等の小塊鉱石をさすものであるが、小塊焼結鉱等の小塊鉱石(粒度1〜5mm、平均粒度3mm)を大塊鉱石に混合したもの、あるいは、小塊焼結鉱等の小塊鉱石を中塊鉱石に混合したものを細粒鉱石バッチとして使用することができ、この混合の場合の細粒鉱石バッチ中の小塊焼結鉱等の小塊鉱石の配合比は30重量%以上の場合を本発明では対象とする。 大塊鉱石とは焼結鉱の場合には粒度が10〜40mm範囲で、平均粒径20mmであり、塊鉱石の場合には粒度が10〜30mm範囲で平均粒度16mmである。中塊鉱石とは、粒度が5〜25mmであり、平均粒度が14mmの焼結鉱や鉱石類である。
【0015】
なお、炉内に装入する1チャージの鉱石のうち細粒鉱石として炉周辺に装入する小塊鉱石の配合比が10重量%未満では、従来通り粗粒鉱石→細粒鉱石の順序で装入しても細粒鉱石バッチの量が少ないため、炉周辺近傍に集中装入した細粒鉱石が炉中心側に崩れ込みを生じる恐れは余りないので従来通り粗粒鉱石→細粒鉱石の順序で装入する。本発明では装入する1チャージ当りの鉱石に対する小塊鉱石の配合比が10重量%以上となった段階で、炉周辺に装入した細粒鉱石が炉中心側に崩れ込むので鉱石の装入順序を入れ替え、細粒鉱石を炉周辺近傍に局部的に集中装入したのち、粗粒鉱石を炉内に均等的装入を行うのが好適である。
【0016】
なお、大塊鉱石または中塊鉱石に小塊焼結鉱等の小塊鉱石を混合した細粒鉱石バッチを用いる場合には、細粒鉱石バッチ中の小塊鉱石が30重量%未満では、細粒鉱石が炉中心側に流れ込んでも、大塊又は中塊鉱石の存在により通気抵抗の増大に対する影響力が小さい。そのため本発明では細粒鉱石中の小塊鉱が30重量%以上となったところで適用するのが好ましい。
【0017】
以下本発明の構成および作用を図面に基づいて説明する。
図1は本発明に係る高炉の炉頂にパラレルに3個の炉頂バンカ10を有するベルレス装入装置を示す概略縦断面図である。図示のように3個の炉頂バンカ10には粗粒鉱石OL 、細粒鉱石OS および塊コークスCL が分割して貯蔵されており、これら粗粒鉱石OL 、細粒鉱石OS および塊コークスは別々に炉内に装入される。
【0018】
このように分割して炉頂ホッパ10に貯蔵されている粗粒鉱石OL 、細粒鉱石OS および塊コークスCL を炉内に装入するに際し、1チャージの炉内装入鉱石のうち、細粒鉱石バッチの配合割合、すなわち(小塊鉱石重量/1チャージ当りの鉱石重量)×100 %が10重量%未満の原料装入スケジュールのときには、従来通りコークス装入に続く鉱石装入では、まず粗粒鉱石(OL )を炉内に均等装入を行ったのち、細粒鉱石(OS )を炉周辺近傍に集中装入を行う。この場合には、炉周辺近傍に局部的に集中装入を行う細粒鉱石(OS )の炉中心側に崩れる可能性は小さいので支障はない。
【0019】
これに対し炉内に装入する1チャージ当りの鉱石に対する小塊鉱石の配合比が10重量%以上になると図4の(a)により説明したように炉周辺近傍に局部的に集中装入した細粒鉱石(OS )が炉中心側に崩れ込んで通気抵抗の上昇を招き炉中心部の通気性を阻害する。
そこで本発明では、炉内に装入する1チャージ当りの鉱石に対する小塊鉱石の配合比が10重量%以上になるときには、従来の粗粒鉱石(OL )→細粒鉱石(OS )の順序を入れ替えて細粒鉱石(OS )→粗粒鉱石(OL )とするものである。すなわち、炉頂バンカ10内に収容して塊コークスCを炉内に装入して塊コークス層4を形成したのち、鉱石の装入段階では、まず炉頂バンカ10内の細粒鉱石(OS )を炉周辺近傍に局部的に集中装入して細粒鉱石層6を形成する。
【0020】
このようにして炉周辺近傍に局部的に装入された細粒鉱石層6は、辷り難いコークス層4上に形成されるので炉中心側への崩れ込みは少なく、 炉中心部まで到達するのを防止できるので、炉中心部のガス流を確保することが可能となる。しかも細粒鉱石(OS )の炉内装入が終了したら、次ぐ装入で炉頂バンカ10内の粗粒鉱石(OL )を炉内に均等的装入を行って細粒鉱石6表面に粗粒鉱石層8を形成するため押え込んだ形となるものであり、崩れ込みを防止できる。このような塊コークス(CL )、細粒鉱石(OS )および粗粒鉱石(OL )の順序で一巡する3バッチの装入によって高炉14への1チャージ装入となる。なお、図1では炉中心部のガス流を向上させるため炉中心部の塊コークス層4をその他の周辺の塊コークス層4の層厚より大きくした場合を示しているが、 本発明は、塊コークス層4が炉中心部から炉周辺壁に亘りほぼ均等にコークス層を形成される場合にも適用可能である。
【0021】
前述のような本発明による高炉炉内への原料装入をベルレス高炉の旋回シュートにより実施する場合についてその装入手順を説明する。 ここで1チャージ当りに装入する焼結鉱を粗粒焼結鉱と細粒焼結鉱に分割し、1チャージ当りに分割装入する小塊焼結鉱の配合比を13重量%とした。
図1に示すように、炉頂バンカ10内の塊コークスCL を高炉14内に装入するに先立って旋回シュート16は傾動位置制御装置30で制御される傾動電動機31により駆動され、また傾動角度検出器32によって規定位置、たとえば炉壁近傍の待機位置から傾動角度θ=52度となるように旋回シュート16の先端を炉壁2側に近いスタート開始位置まで傾動させて一旦傾動を停止する。
【0022】
次に旋回駆動装置33により旋回電動機34を駆動して旋回シュート16を所定の回転速度=7.5rpmで旋回を開始すると共に、流量調整ゲート制御装置36の指令により流量調整ゲート12を所定開度開いて、炉頂バンカ10に貯蔵してある塊コークスCL を集合ホッパ22を介して高炉14内に設置されている旋回シュート16上に導入し、旋回シュート16の先端からダンプさせることにより炉内への塊コークス(CL )の導入が開始される。
【0023】
このとき、旋回制御装置33の指令により旋回シュート16の旋回を制御すると共に、傾動位置制御装置30の指令により、旋回シュート16の傾動角度θを選定範囲である52度から42度までしだいに炉壁2側から炉内側に変化させながら炉内を定められた旋回パターンに沿って旋回させる。このようにして通常の塊コークス層4を形成するのに必要な塊コークス(CL )を炉内の横断全面に炉半径方向での必要な層厚分布(図1では炉周辺部から中心部への塊コークスの流れ込みにより炉中心部のコークス層4の層厚が周辺部の層厚より大きくなったコークス層厚分布を示す)が達成できるように旋回シュート12の先端より炉内に装入する。
【0024】
前述のような塊コークス(CL )の装入によって上面中央が窪んだ前チャージの上に必要なコークス層4が形成される。炉頂バンカ10内から所定量の塊コークス(CL )の装入が終了したら直ちに流量調整ゲート装置36の指令により流量調整ゲート12を閉じる。引続き傾動位置制御装置30の指令により制御される傾動電動機31により旋回シュート16を細粒鉱石の炉周辺装入を行うのに必要な傾斜角度θ=52度まで傾動させる。このとき傾動角度検出器32によって規定位置θ=52度を検出したら傾動位置制御装置30は停止指令を傾動電動機31に与えて旋回シュートの傾動を直ちに停止する。
【0025】
次に旋回制御装置33の指令により旋回電動機34を駆動して旋回シュート16を所定の回転速度=7.5rpmで旋回を開始すると同時に細粒鉱石(OS )の入った炉頂バンカ10の流量調整ゲート12が流量調整ゲート制御装置36の指令により所定開度に開けられることで細粒鉱石(OS )が炉頂バンカ10から落下を始め、漏斗状の集合ホッパ22を介して旋回シュート16に導かれる。炉周辺側に傾斜した状態で旋回している旋回シュート16にガイドされて細粒鉱石(OS )が炉周辺近傍に局部的に集中装入される。なお、旋回シュート16の旋回方向は正逆いずれの回転でもよい。
【0026】
かくして中央部が窪んだコークス層4の炉周辺近傍に分割装入された細粒鉱石層6は分割装入する細粒鉱石バッチ配合比の10重量%以上における上昇に連れて若干ではあるが炉中心側に流れ込むが、コークス層4上に装入されるため図1に示すように炉中心部まで到達することは殆どなく、炉中心部のガス流を確保することができる。
【0027】
このようにして旋回シュート16から細粒鉱石(OS )を炉周辺近傍に局部的に集中装入する操作により所定量の細粒鉱石層6が形成されたら、細粒鉱石(OS )の入った炉頂バンカ10の流量調整ゲート12を閉じた後、粗粒鉱石(OL )の入った炉頂バンカ10の流量調整ゲート12を開とする。同時に旋回シュート16を所定の回転速度7.5rpmで回転制御すると共に、傾動角度θを設定範囲である47度から35度までしだいに炉壁2側から炉内側に変化させながら炉内を定められた旋回シュート16の旋回パターンに沿って旋回される。
【0028】
前述のようにしてコークス層4の炉周辺近傍に細粒鉱石層6を形成した装入物表面上に粗粒鉱石(OL )を所定量装入して粗粒鉱石層8を形成したら粗粒鉱石(OL )の入った炉頂バンカ10の流量調節弁12を閉じて装入を停止する。図1では粗粒鉱石バッチ層8が中央部でコークス層4が露出した状態となっているが、これは装入途上を示しているためであり、炉半径方向の断面ではほぼ均等な層厚に装入するものである。なお、場合よっては粗粒鉱石層8を図のようにして、コークス層4の中心部の通気性を一層向上することも可能である。
【0029】
このような塊コークス(CL )、細粒鉱石(OS )および粗粒鉱石(OL )という順序でそれぞれのバッチを装入して1チャージの原料装入を終了したら旋回位置制御装置33の指令により旋回電動機34を停止した後、傾動位置制御装置30の指令により傾動電動機31を駆動して旋回シュート16を炉周側の待機位置へ傾動させる。傾動角度検出器32によって待機位置に戻ったことを検出したら傾動位置制御装置30の指令により傾動電動機31を停止して旋回シュート16を待機させ3バッチ、1チャージの原料装入を完了する。炉頂シーケンス制御装置37は、前述の傾動制御装置33、流量制御装置36を含めて一連の原料制御を行うものである。
【0030】
前述のように本発明においては、高炉14内に装入する1チャージ当りの全鉱石量=粗粒鉱石(OL )+細粒鉱石(OS )中の小塊鉱石の配合比(小塊鉱石量/全鉱石量)×100 重量%を増加する途中で、高炉14の炉壁2の周辺近傍に局部的に集中装入した細粒鉱石層6が炉中心側に崩れ込みを始める小塊鉱石の配合比まで増加した段階、すなわち10重量%以上の段階で粗粒鉱石(OL )→細粒鉱石(OS )の鉱石装入順序を細粒鉱石(OS )→粗粒鉱石(OL )に切り替えることを骨子としている。
【0032】
【実施例】
以下、本発明の実施例について説明する。
内容積4500m3 のベルレス高炉において、出銑比1.9 t/dm3 のときコークス比 420kg/tの条件で図1に示すように3個の炉頂バンカを有するベルレス装入装置の下部に設けた旋回シュート16を前述の手順により操作して炉頂バンカ10を切り替えながら塊コークス(CL )の装入では、旋回シュート12を炉壁側から炉中心側へ傾斜角度θを52度から42度まで傾斜を変化させつつ7.5rpmの回転速度で12回旋回して塊コークス(CL )を30t/チャージ装入して炉内にコークス層4を形成する。
【0033】
また炉周辺近傍への細粒鉱石(OS )(ここでは粒度選別により得られた粒度1〜5mm範囲で平均粒度3mmの小塊焼結鉱の単味を使用)の装入では、細粒焼結鉱の利用率向上を達成するため、全鉱石量=粗粒鉱石(OL )+細粒鉱石(OS )のうち、分割装入にあてる小塊焼結鉱の配合比=〔OS /(OL +OS )〕×100 を13重量%とした。
【0034】
かくして旋回シュート12を炉壁2の方向に向け傾斜角度θ=52度として7.5rpmの回転速度で5回旋回して16t/チャージ装入し、炉周近傍に細粒鉱石層6を形成する。さらに粗粒鉱石(OL )(ここでは粒度選別により得られた粒度10〜40mm範囲で平均粒度20mmの大塊焼結鉱を使用)の炉内装入では、旋回シュート12を炉壁側から炉中心側に傾斜角度θを47度から35度まで傾斜を変化させつつ7.5rpmの回転速度で10回旋回して 110t/チャージ装入して炉内に粗粒鉱石層8を形成する。
【0035】
図2は高炉に装入する鉱石に小塊焼結鉱を多配合する前、鉱石を分割して小塊焼結鉱を多配合比(小塊焼結鉱/全鉱石)×100 =11重量%として粗粒鉱石OL →細粒鉱石OS (炉周辺装入)の順序で炉内に装入する従来装入方法および、小塊焼結鉱を多配合比(小塊焼結鉱/全鉱石)×100 =13重量%として細粒鉱石OS (炉周辺装入)→粗粒鉱石OL 装入の順序で炉内に装入する本発明装入法に切り替えた場合の炉周辺近傍に局部的に分割して集中装入する小塊焼結鉱の配合比(重量%)と炉内通気抵抗の推移を切替前後により月別に比較して示したものである。
【0036】
図2に示すように小塊焼結鉱を多配合する前の従来法では、通気性を阻害する小塊焼結鉱が6〜7重量%と低いので炉内通気抵抗が小さく通気性が良好である。これに対して小塊焼結鉱の配合比が全鉱石の10重量%前後となる場合において、粗粒鉱石→細粒鉱石(炉周辺に局部的に分割装入)という順序で鉱石を装入する従来法では、炉周辺に装入した小塊焼結鉱が炉中心部に向けて崩れ込むため炉内通気抵抗が急上昇して通気性が悪化することを示している。
【0037】
これに比べて、小塊焼結鉱が10重量%以上となる場合において、細粒鉱石(炉周辺に局部的に分割装入)→粗粒鉱石という順序で鉱石を装入する本発明法では、1チャージで装入する鉱石のうち小塊焼結鉱の配合比が10重量%以上と高いにもかかわらず炉周辺近傍に装入した小塊焼結鉱の炉中心側への崩れ込みが軽減されるため炉内通気抵抗が比較的小さく、炉内に装入した原料が良好な通気性を保つことができるのを裏付けている。
【0038】
【発明の効果】
以上説明したように本発明では、ベルレス高炉内に装入する1チャージ当りの全鉱石量のうち炉周辺近傍に分割して装入する小塊鉱石量の配合比を増加して行く途中で、前記炉周辺近傍に局部的に集中装入した細粒鉱石がその前バッチとして炉内に装入してある粗粒鉱石層上を炉中心側に崩れ込みを始める配合比まで増加した段階で、鉱石の装入順序を入れ替え、まず細粒鉱石をその前バッチとして炉内に装入してあるコークス層の炉周辺近傍に局部的に集中装入を行い、通気性を低下する原因になる細粒鉱石が炉中心側に崩れ込むのを防止して、炉中心側の通気性を確保する。
【0039】
このようにして炉周辺近傍に細粒鉱石層を形成した後に、細粒鉱石に比較して通気性のよい粗粒鉱石を炉内に均等的に装入を行うことによって炉中心側の通気性を良好にするものであり、本発明によれば小塊焼結鉱を高炉装入に利用する割合を大きくすることができると共に、通気性の確保により、炉中心部の装入物が活性化され安定した高炉操業を行うことができる。
【図面の簡単な説明】
【図1】本発明に係るベルレス高炉の炉頂装入装置を示す概略縦断面図である。
【図2】細粒焼結鉱多配合前の従来装入法、細粒焼結鉱10重量%の多配合比で小塊焼結鉱を含む細粒鉱石を粗粒鉱石層上の炉周辺近傍に分割装入する従来装入法および細粒焼結鉱10重量%以上の多配合比でコークス層上の炉周辺近傍に装入する本発明装入法の細粒焼結鉱配合比(重量%)および炉内通気抵抗との切替え前後の変動を月別に比較して示す線図である。
【図3】本発明例の鉱石装入順序と装入した塊コークス(CL )、細粒鉱石(OS )および粗粒鉱石(OL )の炉内装入状況を図3(a)の線図で示し、炉壁−炉中心−炉壁までの温度分布を図3(b)の線図で示す。
【図4】従来例の鉱石装入順序と装入した塊コークス(CL )、粗粒鉱石(OL )および細粒鉱石(OS )の炉内装入状況を図4(a)の線図で示し、炉壁−炉中心−炉壁までの温度分布を図4(b)の線図で示す。
【符号の説明】
2 炉壁
4 コークス層
6 粗粒鉱石層
8 細粒鉱石層
10 炉頂バンカ
12 流量調整ゲート
14 高炉
16 旋回シュート
18 ダンプパターン
20 炉内中心部
22 集合ホッパ
30 傾動位置制御装置
31 傾動電動機
32 傾動角度検出器
33 旋回位置制御装置
34 旋回電動機
35 旋回角度検出器
36 流量調整ゲート制御装置
37 炉頂シーケンス制御装置[0001]
[Industrial applications]
The present invention relates to a method of charging a bellless blast furnace, which secures a central gas flow by adjusting a lamination state of charged materials (coke and ore) in a bellless blast furnace at an ore charging stage.
[0002]
[Prior art]
In general, a bell-type blast furnace uses a large bell at the top of the furnace and a movable armor plate, and a bell-less blast furnace uses a swirling chute to form coke and iron-containing ores such as lump ore, sintered ore, pellets, etc. The charges are alternately charged, thereby alternately depositing coke and ore layers in the furnace. The coke layer and the ore layer thus deposited in the furnace gradually descend in the furnace, and the high-temperature CO generated by the reaction between the hot air blown from the tuyere at the bottom of the furnace and the coke charged in the furnace. After the ore is heated and reduced by the gas to form a softened cohesive zone, the droplets pass between the coke layers and the molten iron accumulates at the furnace bottom.
[0003]
In such a blast furnace operation, it is necessary to appropriately control the gas flow distribution in the radial direction in the furnace and to stably reduce and dissolve ore in the furnace. In order to control the gas flow distribution in the furnace radial direction, a method of controlling the weight distribution and particle size distribution of coke and ore (Ore) in the furnace radial direction has been adopted. In particular, when depositing a coke layer and an ore layer alternately in the furnace, a coke layer almost continuous at the center of the furnace is formed, and the cohesive zone is formed by centralizing the gas flow distribution in the blast furnace. It is known to maintain an inverted V-shape to stabilize the furnace condition of a blast furnace.
[0004]
Japanese Unexamined Patent Publication No. 55-28308 discloses that a charged raw material such as sinter and coke is divided into a plurality of batches each having a predetermined particle size, and the batch type and charged amount are determined. A method of operating a blast furnace in which selective and uniform charging in the circumferential direction of the furnace or local selective charging is disclosed. In Example 1 of the same publication, p. 48, a batch (or an intermediate grain) of a coarse grain portion of the divided ore is uniformly charged into the furnace section, and a (intermediate grain) or a fine grain portion of The case where the peripheral gas flow is suppressed by charging the batch is described.
[0005]
As described above, when the coarse ore batch is uniformly charged in the furnace section and the fine-grained batch is charged near the furnace periphery, conventionally, the coarse ore batch → the fine ore batch is used in the conventional order. Had been charged. That is, as shown in FIG. 4 (a), first, a coarse ore batch containing no small lump ore such as a small sinter ore on a coke, for example, a ore falling from a large bell in a bell type blast furnace is adjusted to a movable armor plate. Meanwhile, in a bellless blast furnace, after adjusting the tilt angle of the swirling chute and uniformly charging the furnace cross section, a fine-grained ore batch such as a small lump sinter was concentratedly charged near the furnace wall.
[0006]
By the way, the preferred method of ore particle size adjustment for blast furnace operation is to increase the particle size range to ensure improved gas permeability in the furnace and to ensure a smooth charge drop, and for that purpose, it is effective to increase the minimum particle size. . However, for example, in the case of sintered ore, the weight ratio near the lower limit particle size is relatively high. Therefore, if the lower limit particle size is increased beyond the current level, the amount of returned ore increases quantitatively and the lump yield of the sintered ore decreases. As a result, even if the blast furnace operation is improved, on the other hand, the productivity of the sintering machine is reduced, and not only the production cost is increased but also the quantity balance of the bulk powder is disturbed, which is disadvantageous.
[0007]
[Problems to be solved by the invention]
For this reason, as described above, the ore charged at one charge is divided into a coarse ore batch and a fine ore batch, and the coarse ore batch is uniformly charged into the furnace. As the concentration ratio of the small ore to the ore charged in one charge into the furnace is increased when the concentrated charge is locally concentrated in the vicinity of the furnace, as shown in FIG. After the coarse ore is charged almost evenly, the fine ore batch (in this case, the ratio of small ore sinter is 16% by weight ) which is locally concentrated near the furnace is limited to the allowable limit of deposition. After that, it starts to collapse toward the center of the furnace, and it is covered with fine ore over the coarse ore up to the center of the furnace.
[0008]
If the surface of the central portion of the furnace interior is covered with the fine ore as described above, the ventilation resistance in the furnace is increased, and in particular, it becomes impossible to secure the gas permeability in the central portion of the furnace. Therefore, as shown in FIG. 4B, the temperature distribution in the furnace diameter direction measured by the furnace top fixed sonde becomes higher around the furnace than at the center of the furnace, and the cohesive zone formed in the furnace has an inverted V-shape. Blast furnace operation cannot be performed normally.
[0009]
The present invention solves the above-mentioned problems of the prior art, and the fine-grained ore batch collapses toward the furnace center even if the mixing ratio of the small ore to the ore per charge charged into the furnace of the bellless blast furnace is increased. It is an object of the present invention to provide a method for charging a raw material into a bellless blast furnace, which can reduce the amount of raw material.
[0010]
[Means to solve the problem]
According to the present invention, in order to achieve the above object, the present invention relates to a method of charging coke and ore alternately into a bellless blast furnace by changing the ore charged in one charge to a coarse ore batch and a small ore. divided into a fine ore batch containing the divided coarse ore batch evenly MatoSoIri have rows in the furnace, the fine granules ore batch to bell-less blast furnace to perform locally concentrated charged into the furnace near the periphery In the raw material charging method, when the compounding ratio of the small ore is small, the coarse ore batch is uniformly charged into the furnace on the coke layer, and then the fine ore batch is locally concentrated around the furnace. When the fine ore batch of ore per charge charged into the furnace is locally concentrated near the periphery of the furnace, the mixture ratio is reduced to a mixing ratio at which collapse starts toward the furnace center. in step lump ore has increased, charged with coarse ore batch and fine ore batch Replacing the mechanism, after the fine ore batches stopped fine ore Komu collapse locally concentrated charged to furnace center side in the furnace near the periphery of the coke layer after coke charged into the coke layer, coarse ore This is a method of charging raw materials into a bellless blast furnace, wherein the batch is uniformly charged into the furnace.
[0011]
According to a second aspect of the present invention, the coarse ore batch and the fine ore batch are charged when the mixing ratio of the small ore to the ore per charge charged into the furnace becomes 10% by weight or more. After changing the charging order, the fine-grained ore batch was locally concentrated near the furnace on the coke bed after charging the coke, and the fine-grained ore that collapsed toward the center of the furnace was stopped on the coke layer. The method for charging raw materials into a bellless blast furnace according to claim 1, wherein the ore batch is uniformly charged into the furnace.
[0012]
According to a third aspect of the present invention, when a small ore is mixed with a large ore or a medium ore to form a fine ore batch, the mixing ratio of the small ore in the fine ore batch is 30% by weight. At this stage, the charging order of the coarse ore batch and the fine ore batch was changed, and the fine ore batch was locally concentrated near the furnace periphery on the coke bed after charging the coke, and the center of the furnace was changed. The method for charging a raw material into a bellless blast furnace according to claim 1 or 2, wherein after the fine ore falling to the side is stopped on the coke layer, the coarse ore batch is charged uniformly in the furnace. It is.
[0013]
[Action]
In the present invention, while increasing the mixing ratio of the small ore to the ore (fine ore batch ore amount + coarse ore batch ore amount) charged in the furnace with one charge, the ore was charged intensively in the vicinity of the furnace. At this stage, the ore charging order was changed at the stage where the mixing ratio of small ore charged in one charge was increased to a mixing ratio of 10% by weight or more that started to collapse into the furnace center side, and the ore charging order was changed. After ore batches (for example, large or medium ore mixed with small ore sinter to form fine ore batch) are intensively charged near the furnace periphery, the coarse ore batch is placed in the furnace. Perform even charging. Therefore not the fine ore batches (here nodules sintered blending ratio 13% by weight of the sintered ore) is on easily large lump ore occurs relatively slip phenomenon as in the conventional in this instrumentation Nyujun, in FIG. 3 (a As shown in (1), the coke is charged on hard- to- slip coke, so that the occurrence of collapse of the fine-grained ore concentrated near the furnace near the furnace center can be greatly reduced. As a result, no increase in the ventilation resistance in the furnace due to the collapse of the fine ore is observed, and the center gas flow in the furnace is secured, so that the temperature distribution in the furnace diameter direction as shown in FIG. The furnace center side is higher than the vicinity of the furnace periphery, and normal bellless blast furnace operation can be performed.
[0014]
Here, the fine ore batch, but is intended to refer to a small lump ore, such as nodules sinter having an average particle size of 3mm in roughly 1~5mm range particle size, nodules ores such as nodules sinter (particle size 1 to 5 mm, the average particle size of 3mm) those that have been mixed in the Daikatamari ore, or may be used after mixing with medium mass ore nodules ore such nodules sinter as fine ore batch The present invention is directed to a case where the mixing ratio of small ore such as small sintered ore in the fine ore batch in the case of this mixing is 30% by weight or more. Large lump ore has a particle size in the range of 10 to 40 mm and an average particle size of 20 mm in the case of sintered ore, and lump ore has a particle size in the range of 10 to 30 mm and an average particle size of 16 mm. The medium lump ore is a sinter ore having a particle size of 5 to 25 mm and an average particle size of 14 mm.
[0015]
If the mixing ratio of the small ore charged around the furnace as fine-grained ore among the one-charge ore charged into the furnace is less than 10% by weight, the coarse-grained ore and the fine-grained ore are charged in the conventional order. Since the amount of the fine ore batch is small even if it enters, there is no danger that the fine ore concentratedly charged near the furnace will collapse into the furnace center side, so the order of coarse ore → fine ore as before To charge. In the present invention, the fine ore charged around the furnace collapses toward the center of the furnace when the compounding ratio of the small ore to the ore per charge reaches 10% by weight or more. It is preferable that the order is changed and the fine ore is locally concentrated near the furnace, and then the coarse ore is uniformly charged into the furnace.
[0016]
In the case of using a fine ore batch in which a small ore such as a small ore is mixed with a large ore ore, if the amount of the small ore in the fine ore batch is less than 30% by weight, the fine ore is reduced. Even if the granular ore flows into the furnace center side, the influence on the increase in the ventilation resistance is small due to the presence of large or medium-sized ore. Therefore, in the present invention, it is preferable to apply the method when the small ore in the fine-grained ore becomes 30% by weight or more.
[0017]
Hereinafter, the configuration and operation of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic longitudinal sectional view showing a bellless charging apparatus having three furnace top bunker 10 in parallel with the furnace top of a blast furnace according to the present invention. Three furnace top in bunker 10 coarse ore O L as shown, fine ores O S and lump coke C L are stored by dividing these coarse ore O L, fine ore O S And the lump coke are charged separately into the furnace.
[0018]
Thus divided and furnace top hopper 10 to the storage has been and coarse ore O L, upon which charged fine ore O S and lump coke C L into the furnace, of the first charge of the furnace interior entrance ores, When the blending ratio of the fine-grained ore batch, that is, (mass of lump ore / weight of ore per charge) × 100%, is less than 10% by weight, the ore charging following the coke charging as in the conventional case is as follows. first after the coarse ore (O L) was uniformly charged into the furnace, for centralized charged fine ore (O S) to the furnace near the periphery. In this case, it should not interfere because less likely to collapse in the furnace center side of the fine ore to perform locally concentrated charged into the furnace near the periphery (O S).
[0019]
On the other hand, when the compounding ratio of the small lump ore to the ore per charge charged into the furnace becomes 10% by weight or more, as described with reference to FIG. in fine ore (O S) is crowded collapse furnace center side to inhibit breathability of the lead furnace center portion increases airflow resistance.
In the present invention therefore, when the compounding ratio of the nodule ore for ore per charge to be charged into the furnace is more than 10% by weight, conventional coarse ore (O L) → fine ore (O S) it is an out of sequence fine ore (O S) → coarse ore (O L). That is, after the lump coke C is placed in the furnace bunker 10 and the lump coke C is charged into the furnace to form the lump coke layer 4, in the ore charging stage, the fine ore (O S ) is locally concentrated near the furnace periphery to form a fine ore layer 6.
[0020]
The fine-grained ore layer 6 locally charged in the vicinity of the furnace in this way is formed on the coke layer 4 which is difficult to slip, so that it is less likely to collapse toward the furnace center and reaches the furnace center. Therefore, it is possible to secure a gas flow in the central part of the furnace. Moreover Once the furnace interior entrance of fine ore (O S) is completed, the coarse ore in the furnace top bunker 10 in the next instrument charged (O L) and performs equally MatoSoIri into the furnace fine ore 6 surface In order to form the coarse ore layer 8, it is pressed down, and collapse can be prevented. Such lump coke (C L), a first charge charged to the fine ore (O S) and coarse ore (O L) blast furnace 14 by three loading batches to cycle in the order. FIG. 1 shows a case where the lump coke layer 4 at the center of the furnace is made larger than the thickness of the other lump coke layers 4 at the center of the furnace in order to improve the gas flow at the center of the furnace. The present invention is also applicable to a case where the coke layer 4 is formed almost uniformly from the furnace center to the furnace peripheral wall.
[0021]
A procedure for charging raw materials into the blast furnace according to the present invention as described above by using a swirling chute of a bellless blast furnace will be described. Here, the sinter charged per charge is divided into coarse-grained sinter and fine-grained sinter, and the blending ratio of the small sinter charged separately per charge is 13% by weight. .
As shown in FIG. 1, the turning chute 16 prior to charging the lump coke C L in the furnace top bunker 10 to the blast furnace 14 is driven by the tilting motor 31 which is controlled by the tilted position control device 30, also tilted The tip of the turning chute 16 is tilted by the angle detector 32 to a start start position close to the furnace wall 2 so that the tilt angle θ is 52 degrees from a predetermined position, for example, a standby position near the furnace wall, and the tilting is temporarily stopped. .
[0022]
Next, the turning drive unit 33 drives the turning motor 34 to start turning the turning chute 16 at a predetermined rotation speed = 7.5 rpm, and the flow rate adjusting gate 12 is opened at a predetermined opening by a command from the flow rate adjusting gate control unit 36. open furnace by introducing on swivel chute 16 the lump coke C L that is stored in a furnace top bunker 10 via a collecting hopper 22 is installed in the blast furnace 14, it is dumped from the tip of the turning chute 16 The introduction of lump coke ( CL ) into the inside is started.
[0023]
At this time, the turning of the turning chute 16 is controlled by the command of the turning control device 33, and the tilt angle θ of the turning chute 16 is gradually increased from the selected range of 52 degrees to 42 degrees by the command of the tilt position control device 30. The inside of the furnace is swirled along a predetermined swirl pattern while changing from the wall 2 side to the inside of the furnace. In this way, the necessary coke ( CL ) necessary for forming the normal coke layer 4 is distributed over the entire cross section in the furnace in the necessary layer thickness distribution in the furnace radial direction (in FIG. 1, from the furnace periphery to the center). Into the furnace from the tip of the revolving chute 12 so as to achieve a coke layer thickness distribution in which the layer thickness of the coke layer 4 at the center of the furnace becomes larger than the layer thickness at the periphery due to the flow of lump coke into the furnace. I do.
[0024]
The charging of the coke (C L ) as described above forms the necessary coke layer 4 on the precharge in which the center of the upper surface is depressed. Furnace top bunker by a command immediately the flow rate control gate 36 After charging is completed 10 within a predetermined amount of lump coke (C L) to close the flow rate control gate 12. Subsequently, the turning chute 16 is tilted by the tilting motor 31 controlled by the command of the tilting position control device 30 to a tilt angle θ = 52 degrees required for charging the fine ore around the furnace. At this time, when the tilt angle detector 32 detects the specified position θ = 52 degrees, the tilt position control device 30 gives a stop command to the tilt motor 31 to immediately stop the tilt of the turning chute.
[0025]
Then the flow rate of the furnace top bunker 10 that contains the starts the turning the turning chute 16 drives the rotation motor 34 at a predetermined rotational speed = 7.5 rpm simultaneously fine ore (O S) by a command of turning the controller 33 fine ore by opened to a predetermined opening degree by a command control gate 12 is the flow rate control gate control device 36 (O S) starts to fall from the furnace top bunker 10, pivoting chute 16 through the funnel-shaped collecting hopper 22 Is led to. Furnace around the guide to pivot the chute 16 is turning in an inclined state on the side fine ore (O S) is locally concentrated charged into the vicinity surrounding the furnace. The turning direction of the turning chute 16 may be either forward or reverse.
[0026]
Thus, the fine ore layer 6 divided and charged in the vicinity of the furnace around the coke layer 4 whose central portion is depressed is slightly increased as the mixing ratio of the fine ore batches charged separately increases at 10% by weight or more. Although it flows into the center side, it hardly reaches the furnace center as shown in FIG. 1 because it is charged on the coke layer 4, and the gas flow in the furnace center can be secured.
[0027]
Once this way fine ore layer 6 of a predetermined amount by turning chute 16 locally intensive operations charged fine ore (O S) to the furnace near vicinity since is formed, the fine ore (O S) after closing the flow rate control gate 12 of the entering the furnace top bunker 10, the flow rate control gate 12 of the entering the furnace top bunker 10 the coarse ore (O L) and opened. At the same time, the rotation of the swing chute 16 is controlled at a predetermined rotation speed of 7.5 rpm, and the inside of the furnace is determined while gradually changing the tilt angle θ from the set range of 47 degrees to 35 degrees from the furnace wall 2 side to the furnace inside. The turning chute 16 is turned along the turning pattern.
[0028]
After forming the coarse ore (O L) and by a predetermined RyoSoIri coarse ore layer 8 coke layer 4 of the furnace near vicinity charge on the surface to form a fine ore layer 6 as described above crude stop charging by closing the flow control valve 12 of the furnace top bunker 10 containing the particle ores (O L). In FIG. 1, the coarse ore batch layer 8 is in a state where the coke layer 4 is exposed at the center, which is because the coke layer 4 is in the process of being charged and has a substantially uniform layer thickness in the cross section in the furnace radial direction. To be charged. In some cases, the coarse-grained ore layer 8 can further improve the air permeability at the center of the coke layer 4 as shown in the figure.
[0029]
Such lump coke (C L), fine ore (O S) and coarse ore (O L) each batch when finished turning position control device raw material charging of the charging to first charge the order of 33 After the turning motor 34 is stopped by the command of (1), the tilt motor 31 is driven by the command of the tilt position control device 30 to tilt the turning chute 16 to the standby position on the furnace peripheral side. When the return to the standby position is detected by the tilt angle detector 32, the tilt motor 31 is stopped by the command of the tilt position control device 30, and the turning chute 16 is put on standby to complete the charging of three batches and one charge. The furnace top sequence control device 37 performs a series of raw material control including the tilt control device 33 and the flow rate control device 36 described above.
[0030]
In the present invention, as described above, the total ore weight per charge to be charged into the blast furnace 14 = coarse ore (O L) + fine ore (O S) compounding ratio of the nodules ore in (nodules While increasing the ore amount / total ore amount) × 100 wt%, the fine ore layer 6 locally concentratedly charged near the periphery of the furnace wall 2 of the blast furnace 14 starts to collapse into the furnace center side. stage increased to the compounding ratio of the ore, i.e. 10 wt% or more stages in the coarse ore (O L) → fine ore ores charging sequence the fine ore (O S) (O S) → coarse ore ( O L ).
[0032]
【Example】
Hereinafter, examples of the present invention will be described.
In a bellless blast furnace having an inner volume of 4500 m 3, at a tapping ratio of 1.9 t / dm 3 and a coke ratio of 420 kg / t, as shown in FIG. the charging of lump coke while switching the furnace top bunker 10 the swivel chute 16 provided by operating the above procedure (C L), the inclination angle θ from 52 degrees turning chute 12 from the furnace wall side to the furnace center side to 42 degrees to change the inclination while forming a coke layer 4 12 times turning to lump coke at a rotation speed of 7.5rpm a (C L) to 30t / charge charging to the furnace.
[0033]
In the loading of fine ore into the furnace near the periphery (O S) (using plain of nodules sinter the average particle size of 3mm in size 1~5mm range obtained by a particle size selected in this case), fine to achieve utilization improving sinter, the total ore weight = coarse ore (O L) + of the fine ore (O S), the compounding ratio of the nodules sinter shed split charging = [O the S / (O L + O S ) ] × 100 was 13 wt%.
[0034]
Thus, the turning chute 12 is turned toward the furnace wall 2 at an inclination angle θ = 52 degrees, and is turned five times at a rotation speed of 7.5 rpm to charge 16 t / charge to form a fine ore layer 6 near the furnace periphery. Further in the furnace interior entrant coarse ore (O L) (using a large mass sinter having an average particle size 20mm in size 10~40mm range obtained by a particle size selected in this case), the furnace turning chute 12 from the furnace wall side While turning the inclination angle θ from 47 degrees to 35 degrees toward the center side, it is turned 10 times at a rotation speed of 7.5 rpm and charged 110 t / charge to form the coarse-grained ore layer 8 in the furnace.
[0035]
FIG. 2 shows that the ore is divided before the ore charged into the blast furnace and the ore is divided into multiple ores, and the small ore sinter is multi-mixed ratio (small ore / all ore) × 100 = 11 weight % as coarse ore O L → fine ore O S conventional charging method is charged into the furnace in order of (furnace near loading) and multi blending ratio nodules sinter (nodules sinter / furnace around when switching to full ore) × 100 = 13% by weight fine ore O S (furnace surrounding charged) → present invention instrumentation Iriho that charged into coarse ore O L furnace with charging order It is a comparison showing the change of the mixing ratio (wt%) of the small sinter ore and the in-furnace ventilation resistance which are locally divided into the vicinity and concentratedly charged, before and after switching, by month.
[0036]
As shown in FIG. 2, in the conventional method before the large amount of small lump sinter is blended, the small lump sinter that inhibits air permeability is as low as 6 to 7% by weight. It is. On the other hand, when the mixing ratio of the small ore is about 10% by weight of the total ore, the ore is charged in the order of coarse ore → fine ore (partially charged around the furnace). In the conventional method, the small ore sinter charged in the periphery of the furnace collapses toward the center of the furnace, which indicates that the in-furnace ventilation resistance rises rapidly and the permeability deteriorates.
[0037]
On the other hand, when the amount of the small sinter becomes 10% by weight or more, the method of the present invention in which the ore is charged in the order of fine-grained ore (charged locally around the furnace) → coarse-grained ore is performed. Despite the high ore ratio of small lump sinter of 10% by weight or more in ore charged in one charge, small lump sinter charged in the vicinity of the furnace collapsed into the furnace center. Because of the reduction, the airflow resistance in the furnace is relatively small, which confirms that the raw material charged in the furnace can maintain good air permeability.
[0038]
【The invention's effect】
As described above, in the present invention, while increasing the mixing ratio of the amount of small lump ore charged in the vicinity of the furnace out of the total amount of ore per charge charged into the bellless blast furnace, At the stage where the fine-grained ore locally concentratedly charged in the vicinity of the furnace has increased to the mixing ratio at which the coarse ore layer charged in the furnace as a previous batch starts to collapse into the furnace center side, The order of charging the ore is changed, and firstly, fine-grained ore is locally concentrated near the furnace around the coke bed charged in the furnace as a previous batch, and fine ore is a cause of reduced air permeability. Prevents ore from falling into the center of the furnace and ensures ventilation at the center of the furnace.
[0039]
After forming a fine-grained ore layer in the vicinity of the furnace in this way, the coarse-grained ore with better permeability than the fine-grained ore is uniformly charged into the furnace, so that the air permeability on the center side of the furnace is improved. According to the present invention, it is possible to increase the ratio of the small sinter used for charging the blast furnace, and to activate the charged material in the central part of the furnace by securing the air permeability. This allows stable blast furnace operation.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a furnace top charging apparatus for a bellless blast furnace according to the present invention.
FIG. 2 shows a conventional charging method before a large amount of fine-grained sinter, and a fine-grained ore containing a small lump sinter at a multi-ratio of 10% by weight of fine-grained sinter, around a furnace on a coarse-grained ore layer In the conventional charging method in which the fine particles are divided and charged in the vicinity, and the compounding ratio of the fine particles in the charging method of the present invention in which the fine particles are charged in the vicinity of the furnace on the coke layer at a multi-ratio of 10% by weight or more ( FIG. 7 is a diagram showing the fluctuations before and after the switching between the weight ratio (% by weight) and the in-furnace airflow resistance in comparison with each other by month.
[3] The present invention Examples of ore charging order and charged the lump coke (C L), 3 the furnace interior inlet conditions of the fine ore (O S) and coarse ore (O L) of (a) A temperature distribution from the furnace wall to the furnace center to the furnace wall is shown by a diagram in FIG. 3B.
[4] Conventional Example ore charging order and charged the lump coke (C L), the line of coarse ore (O L) and fine ore FIG furnace interior inlet conditions of (O S) 4 (a) FIG. 4B shows the temperature distribution from the furnace wall to the furnace center to the furnace wall in the diagram of FIG.
[Explanation of symbols]
2 Furnace wall 4 Coke layer 6 Coarse ore layer 8 Fine ore layer 10 Furnace top bunker 12 Flow control gate 14 Blast furnace 16 Swirling chute 18 Dump pattern 20 Furnace center 22 Collective hopper 30 Tilt position control device 31 Tilt motor 32 Tilt Angle detector 33 Swing position control device 34 Swing motor 35 Swing angle detector 36 Flow rate adjustment gate control device 37 Furnace top sequence control device