JP2004169140A

JP2004169140A - Reduction apparatus and reduction method for direct-reduced iron with low reduction ratio

Info

Publication number: JP2004169140A
Application number: JP2002337628A
Authority: JP
Inventors: Hiroshi Kajitani; 寛士梶谷; Hiroshi Nakajima; 宏中嶋; Keiichi Sato; 恵一佐藤
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2002-11-21
Filing date: 2002-11-21
Publication date: 2004-06-17

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction apparatus and a reduction method for direct-reduced iron with a low reduction ratio, whereby a reduction product with a low reduction ratio can be produced without decreasing the crushing strength of the direct-reduced iron. <P>SOLUTION: The SiO<SB>2</SB>and CaO contents in a reduction product raw material measured with a reduction product measuring instrument 11, the SiO<SB>2</SB>and CaO contents in a raw material measured with a reducing agent measuring instrument 12, and the SiO<SB>2</SB>and CaO contents in a binder measured with a binder measuring instrument 13 are taken in as numerical signals, and a material for basicity adjustment is measured so as to set the basicity of the materials at a specified value and supplied to mixer 21. The reduction product raw material, the carbon-material-containing raw material, the binder, and the material for basicity adjustment supplied to the mixer 21 are kneaded in the presence of water, then molded into a massive state with a molding machine 22 to produce a massive raw material 70, dried with a dryer 23, and supplied with a raw material supplying machine 24 to the inside of a rotating bed type reduction furnace 30. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、酸化鉄を還元する低還元率還元鉄の還元設備及び還元方法に関する。
【０００２】
【従来の技術】
図６は従来の技術の還元設備である回転床式還元炉への原料供給及び回転床式還元炉からの排気フロー図である。
【０００３】
還元鉄製造用の原料である酸化鉄を主体とした還元鉄の鉄源となる被還元体原料、還元材となる炭材を含む炭材含有材料、粘結剤となるバインダは、個別のサイロすなわち、被還元体サイロ１，還元材サイロ２，バインダサイロ３からそれぞれ供給される。被還元体サイロ１から供給される被還元体原料は、被還元体乾燥器５で乾燥した後、被還元体粉砕機６及び被還元体分級器７により粉砕し分級される。一方還元材サイロ２から供給される炭材含有材料は、還元材粉砕機８及び還元材分級器９で粉砕し分級される。
【０００４】
被還元体分級器７で分級された被還元体原料は被還元体計量器１１により、還元材分級器９で分級された炭材含有材料は還元材計量器１２により、バインダサイロ３から供給されたバインダはバインダ計量器１３により所定分量ずつ計量されてミキサ２１へ送られ、必要含水量で混練される。ミキサ２１で混練された原料が成形機２２へ送られ、必要水分量のもとでペレット又はブリケットなどの塊状原料７０に形成され、乾燥器２３により乾燥された後、原料供給機２４により回転床式還元炉３０内へ供給される（例えば、特許文献１参照。）。
【０００５】
回転床式還元炉３０には、炉内に還元に使用する熱ガスを発生させる複数の熱ガスバーナ４１と、使用された熱ガスを排気する排気ダクト４４と、還元済みペレットを排出する排出機４５と、炉内のＣＯ比調節用の複数の流量調節手段４６付空気供給器４２が設けられている。回転床式還元炉３０では燃料と燃焼用空気が熱ガスバーナ４１へ供給されて燃焼し回転床式還元炉３０内は高温（１３００〜１４００℃）に保持され、回転床が一周する間に供給された塊状原料７０は１３００℃程度まで昇温し還元されて還元鉄となり、回転床式還元炉３０から可搬容器４７へ取出され次工程へ送られる。回転床式還元炉３０内温度は回転床式還元炉３０に設置された温度計６５にて計測される。回転床の回転速度は回転床式還元炉３０に設けられた回転機（図示せず）にて制御される。
【０００６】
排気ダクト４４へ逃がされる熱ガスは、アフターバーナ４８付水冷ダクト４９で未燃焼のガス成分を燃焼・冷却させた後、更に二次冷却器５１、熱交換器５２、三次冷却器５３等により冷却し、集塵機５４、排気ファン５５を経て煙突５６から大気中へ排出される（例えば、特許文献２参照。）。
【０００７】
このような低還元率還元鉄の還元設備は、従来、還元鉄の還元率を高めることを目標とし、一般的に還元率が８０％超まで還元させていた。このような高い還元率を得るには塊状原料７０を１３００℃程度まで昇温させ、さらに回転床式還元炉３０内での滞留時間を長くする必要がある。しかしながら、回転床式還元炉３０内での滞留時間が長くなると、一旦還元された還元鉄が回転床式還元炉３０内ガス中のＣＯ_２により再び酸化する可能性がある。そこで、この還元鉄の再酸化を防止するために、回転床式還元炉３０内ガス中のＣＯとＣＯ_２の比［（ＣＯ／（ＣＯ＋ＣＯ_２））以下これをＣＯ比と言う］を０．２以上に維持している。具体的には、回転床式還元炉３０の側壁部に設けた空気供給器４２でＣＯ燃焼用投入空気量を制御調整することで維持している。
【０００８】
すなわち、上述した設備による還元鉄の還元では、回転床式還元炉３０内のガスのＣＯ比を０．２以上に調節し、還元率８０％超対応の炉内温度（１３００〜１４００℃）、滞留時間に炉操業条件を設定し、塊状原料７０を供給して高温下で還元鉄を生成させ、還元鉄を排出する工程で還元を行っている。
【０００９】
このため、従来の設備では、ＣＯ比（０．２以上）相当の未燃のＣＯを炉外に放出することになり、未燃ＣＯを有効熱源として十分に活用できないでいる。また、回転床式還元炉３０から排気ダクト４４へ逃がされた未燃ＣＯは、アフターバーナ４８付の水冷ダクト４９で燃焼させる等、余分な設備と処理が必要である。
【００１０】
また、取り出される還元鉄は、還元率が８０％を超える領域まで高められることにより、還元された金属鉄同士の結合や高温保持されるために生じるスラグボンドの形成などが還元鉄内部で起こり、還元鉄の圧壊強度を保持してきた。さらに、この低還元率還元鉄の還元設備で製造された還元鉄は、後工程の溶解炉で溶解され銑鉄を得ることを目的としており、還元鉄の還元率は８０％超が一般的とされていた。
【００１１】
しかしながら、近時、溶解炉の型式によっては、還元率８０％以下の低還元率の方が、低還元率還元鉄の還元設備と溶解炉を組み合わせた際の総エネルギー効率が良くなり、経済的であるということがいわれている。還元率８０％以下の低還元率で還元鉄の還元を行うために、図６のような従来の低還元率還元鉄の還元設備において、例えば回転床式還元炉３０内ガス温度は１３００℃以下の比較的低温度で、かつ回転床式還元炉３０内の滞留時間を短くすることで低還元率還元鉄の製造をすることが検討されている。
【００１２】
【特許文献１】
特開２０００−２７３５５２号公報（第１図）。
【特許文献２】
特開平１１−１２９８０６号公報（第１図）。
【００１３】
【発明が解決しようとする課題】
ところが、低還元率還元鉄の製造を単に回転床式還元炉内温度の低下、滞留時間の短縮などの変更だけで行うと、▲１▼低還元率のために還元された金属鉄が少なく結合力が弱く、▲２▼回転床式還元炉内温度が低く滞留時間が短いことからスラグボンドが形成し難く、▲３▼低還元率時に起こる酸化鉄の相変化による膨れ現象が発生し還元鉄が膨らみクラックを生じる、などの理由から還元鉄の圧壊強度が弱くなり以下のような問題が生じる。
（１）還元鉄を回転床式還元炉から排出する時に紛化・破損し、回転床式還元炉からの排出が困難になる。
（２）排出時に紛化・破壊した還元鉄の一部は、ダストとして回転床式還元炉内のガス中に浮遊し、回転床式還元炉内壁及び排ガス設備ダクト壁に付着する。
（３）回転床式還元炉から排出された還元鉄が、搬送中に紛化・破損し、ダストを発生する。
さらに、低還元率還元鉄の製造を行う場合の回転床式還元炉内のＣＯ比に関する運転条件は、まだ解明されていない状態にある。
【００１４】
本発明は、かかる従来の問題に対し、還元鉄の圧壊強度を低下させずに、効率の良い低還元率還元鉄の製造に係る炉内のＣＯ比を設定し、被還元体を低還元率で製造できる低還元率還元鉄の還元設備及び還元方法について提供することを課題としたものである。
【００１５】
【課題を解決するための手段】
上記課題を解決するために、請求項１に記載の本発明は、酸化鉄を主体とした還元鉄の鉄源となる被還元体原料を収納する被還元体サイロと、還元材となる炭材を含む炭材含有原料を収納する還元材サイロと、粘結原料となるバインダを収納するバインダサイロと、を備えた原料供給手段と、前記酸化鉄を熱ガスで還元する回転床式還元炉と、前記原料供給手段より供給された複数の原料を混合する混合機と、前記混合機により混合された前記原料を成形する成形手段と、前記成形手段で成形された前記原料を乾燥する乾燥手段と、前記乾燥手段で乾燥された前記原料を前記回転床式還元炉に供給する供給手段と、前記回転床式還元炉より前記熱ガスを排気する排気ダクトと、を備えた還元鉄を製造する低還元率還元鉄の還元設備において、前記原料供給手段が、塩基度を調整するための塩基度調整用原料を収納する塩基度調整サイロを備えたことを特徴とする。
【００１６】
上記構成によれば、還元鉄の圧壊強度を低下させずに、被還元体を低還元率で製造するための、原料に添加する塩基度調整用原料を保存し供給することができる。
【００１７】
また、上記課題を解決するために、請求項２に記載の本発明は、請求項１に記載の本発明において、前記被還元体サイロと前記混合機との間に前記被還元体原料中のＳｉＯ_２量とＣａＯ量を計量する被還元体計量器を備え、前記還元材サイロと前記混合機との間に前記炭材含有原料中のＳｉＯ_２量とＣａＯ量を計量する還元材計量器を備え、前記バインダサイロと前記混合機との間に前記バインダ中のＳｉＯ_２量とＣａＯ量を計量するバインダ計量器を備え、前記塩基度調整サイロと前記混合機との間に塩基度調整計量器を備えたことを特徴とする。
【００１８】
上記構成によれば、被還元体原料中と炭材含有原料中とバインダ中のＳｉＯ_２量とＣａＯ量を計量し、さらに塩基度（ＣａＯ／ＳｉＯ_２比）を所定の値にするため、上記各原料に添加する塩基度調整用原料を塩基度調整計量器により調整することができる。前記前記被還元体原料中、前記炭材含有原料中及び前記バインダ中のＳｉＯ_２量とＣａＯ量を計量するそれぞれの計量器は、ＳｉＯ_２量とＣａＯ量とをそれぞれ個別に計量する複数の計量器で構成しても、本発明の範囲であることはいうまでもない。
【００１９】
また、上記課題を解決するために、請求項３に記載の本発明は、請求項２に記載の本発明において、前記被還元体計量器が計量する前記被還元体原料中のＳｉＯ_２量とＣａＯ量と、前記還元材計量器が計量する前記還炭材含有原料中のＳｉＯ_２量とＣａＯ量と、前記バインダ計量器が計量する前記バインダ中のＳｉＯ_２量とＣａＯ量と、を基に、前記混合機に供給する原料の塩基度を０．３以上０．６以下になるように前記塩基度調整計量器が前記塩基度調整用原料を前記混合機に供給するよう構成したことを特徴とする。
【００２０】
上記構成によれば、被還元体原料中と炭材含有原料中とバインダ中のＳｉＯ_２量とＣａＯ量を計量し、さらに塩基度（ＣａＯ／ＳｉＯ_２比）を有効値である０．３以上０．６以下になるように、上記各原料に添加する塩基度調整用原料を塩基度調整計量器により調整し混合機に供給することができる。塩基度は０．３以上０．６以下が有効であるが、０．４以上０．５以下が更により高い効果を示す。
【００２１】
また、上記課題を解決するために、請求項４に記載の本発明は、請求項１に記載の本発明において、前記混合機と前記成形手段の間に前記混合原料中のＳｉＯ_２量とＣａＯ量を計量する混合原料計量器を備え、前記塩基度調整サイロと前記混合機との間に塩基度調整用計量器を備えたことを特徴とする。
【００２２】
上記構成によれば、原料を全て混合機にて混合した後、混合原料中のＳｉＯ_２量とＣａＯ量を計量し、その計量値に基いて塩基度調整用原料を塩基度調整計量器により調整するので、各原料の混合機に入る前にそれぞれ計量する場合に比較して塩基度の調整精度は劣るものの、計量器の数を少なくすることができる。前記混合原料中のＳｉＯ_２量とＣａＯ量を計量する混合原料計量器はＳｉＯ_２量とＣａＯ量をそれぞれ個別に計量する複数の計量器で構成しても本発明の範囲であることはいうまでもない。
【００２３】
また、上記課題を解決するために、請求項５に記載の本発明は、請求項４に記載の本発明において、前記混合原料計量器が計量する前記混合原料中のＳｉＯ_２量とＣａＯ量を基に、前記混合機に供給する原料の塩基度を０．３以上０．６以下になるように前記塩基度調整用計量器が前記塩基度調整用原料を前記混合機に供給するよう構成したことを特徴とする。
【００２４】
上記構成によれば、原料を全て混合機にて混合した後、混合された原料のＳｉＯ_２量とＣａＯ量を計量し、塩基度調整用原料を塩基度調整計量器により調整して混合機に供給することにより、塩基度（ＣａＯ／ＳｉＯ_２比）を有効値である０．３以上０．６以下になるように調整することができる。塩基度は０．３以上０．６以下が有効であるが、０．４以上０．５以下が更により高い効果を示す。
【００２５】
また、上記課題を解決するために、請求項６に記載の本発明は、請求項１乃至５のいずれかに記載の本発明において、前記塩基度調整用原料がＣａ化合物を含有したことを特徴とする。
【００２６】
上記構成によれば、例えば、塩基度調整用原料としてＣａＣＯ_３を供給することができる。塩基度調整用原料は塩基度（ＣａＯ／ＳｉＯ_２比）が調整できればよく、ＣａＣＯ_３のみならず他のＣａ化合物を適宜選択しても塩基度の調整が可能であれば本発明の範囲であることはいうまでもない。
【００２７】
また、上記課題を解決するために、請求項７に記載の本発明は、請求項１乃至６のいずれかに記載の本発明において、前記回転床式還元炉が一酸化炭素濃度を測定するＣＯ測定器と、二酸化炭素濃度を測定するＣＯ_２測定器と、を備えたことを特徴とする。
【００２８】
上記構成によれば、一酸化炭素濃度と二酸化炭素濃度を測定することにより、回転床式還元炉内のＣＯ比（ＣＯ／（ＣＯ＋ＣＯ_２））を知ることができる。計測したＣＯ量及びＣＯ_２量、又はＣＯ比をＣＯ燃焼用空気量にフィードバックし、回転床式還元炉内のＣＯ量を管理できる。
【００２９】
また、上記課題を解決するために、請求項８に記載の本発明は、請求項７に記載の本発明において、前記排気ダクトに少なくとも一酸化炭素濃度を測定するダクト用ＣＯ計測器又は酸素濃度を測定するダクト用Ｏ_２計測器を備えたことを特徴とする。
【００３０】
上記構成によれば、排気ダクトにＣＯ計測器もしくはＯ_２計測器を備えることで、回転床式還元炉外に排出されるＣＯ量を知ることができるため、計測したＣＯ量もしくはＯ_２量をＣＯ燃焼用空気量にフィードバックし、回転床式還元炉外排出ＣＯ量を管理することができる。
【００３１】
また、上記課題を解決するために、請求項９に記載の本発明は、請求項１乃至８のいずれかに記載の本発明において、前記回転床式還元炉が酸素を含有する流体を供給する複数の流体供給手段を備えたことを特徴とする。
【００３２】
また、上記課題を解決するために、請求項１０に記載の本発明は、請求項９に記載の本発明において、前記酸素を含有する流体が空気又は酸素を富化された酸素含有ガスであることを特徴とする。
【００３３】
上記請求項９及び１０の構成によれば、回転床式還元炉内のＣＯを酸素で酸化させてＣＯ_２とすることにより、回転床式還元炉内のＣＯ比を調整することができる。
【００３４】
また、上記課題を解決するために、請求項１１に記載の本発明は、請求項９又は１０に記載の本発明において、ＣＯ比を０．２以下となるように前記流体供給手段の流体供給量を調整する流体制御手段を備えたことを特徴とする。
【００３５】
上記構成によれば、従来の０．２以上のＣＯ比に比較し、炉外に放出する未燃ＣＯを減少させ、また、アフターバーナ付の水冷ダクトで燃焼させる等の余分な設備と処理を縮小させるか又は必要としなくなる。ＣＯ比は０．２以下とするが、好ましくは０．１以下、更に好ましくは０．０１以下が無駄なＣＯを使用しない点で有効であり、さらに、ＣＯを含まないガスの使用はさらに有効である。
【００３６】
また、上記課題を解決するために、請求項１２に記載の本発明は、請求項１乃至１１に記載の本発明において、前記回転床式還元炉が、炉内の温度を計測する温度測定器と、炉内に熱ガスを発生させる複数の熱ガスバーナと、を備えたことを特徴とする。
【００３７】
また、上記課題を解決するために、請求項１３に記載の本発明は、請求項１２に記載の本発明において、前記温度測定器の示す温度が１３００℃以下になるように前記熱ガスバーナを調整する熱ガスバーナ調整手段を備えたことを特徴とする。
【００３８】
上記請求項１２及び１３の構成によれば、回転床式還元炉内の温度を計測し、前記温度を１３００℃以下の所定の温度に設定することできる。回転床式還元炉内の温度は１２５０℃以下、更に１２００℃以下においても本発明の効果を有するが、９００℃以下の温度になれば酸化鉄が還元されないため、９００℃以上には保持する必要がある。
【００３９】
また、上記課題を解決するために、請求項１４に記載の本発明は、請求項１乃至１３のいずれかに記載の本発明において、酸化鉄の還元率が８０％以下となるように前記回転床式還元炉の回転速度を調整可能な回転手段を備えたことを特徴とする。
【００４０】
上記構成によれば、回転床式還元炉の回転速度を調整して還元率８０％以下の低還元率で回転床式還元炉を運転することにより、低還元率還元鉄の還元設備と溶解炉を組み合わせた際の総エネルギー効率が良くなり経済的となる。
【００４１】
また、上記課題を解決するために、請求項１５に記載の本発明の塊状原料は、還元鉄の鉄源となる被還元体原料と、還元材となる炭材を含む炭材含有原料と、粘結原料となるバインダと、塩基度を調整するための塩基度調整用原料と、を含み、塩基度を０．３以上０．６以下とするように配合したことを特徴とする。
【００４２】
上記構成によれば、還元鉄の鉄源となる被還元体原料と、還元材となる炭材を含む炭材含有原料と、粘結原料となるバインダと、塩基度を調整するための塩基度調整用原料と、を含み、塩基度を０．３以上０．６以下とするように配合した塊状原料を回転床式還元炉に供給することができる。塩基度は０．３以上０．６以下が有効であるが、０．４以上０．５以下が更により高い効果を示す。
【００４３】
また、上記課題を解決するために、請求項１６に記載の本発明の塊状原料は、請求項１５に記載の本発明において、前記塩基度調整用原料がＣａ化合物を含有したことを特徴とする。
【００４４】
上記構成によれば、例えば、塩基度調整用原料であるＣａＣＯ_３を含有した回転床式還元炉用の塊状原料を供給することができる。塩基度調整用原料は塩基度が調整できればよく、ＣａＣＯ_３のみならず他のＣａ化合物を適宜選択しても塩基度の調整が可能であれば本発明の範囲であることはいうまでもない。
【００４５】
また、上記課題を解決するために、請求項１７に記載の本発明の方法は、還元鉄の鉄源となる被還元体原料と、還元材となる炭材を含む炭材含有原料と、粘結原料となるバインダと、塩基度を調整するための塩基度調整用原料と、を含む塊状原料を回転床式還元炉で還元処理することを特徴とする。
【００４６】
上記方法によれば、原料に塩基度調整用原料を含んだ塊状原料を用いて、還元鉄の圧壊強度を低下させずに、被還元体を低還元率で製造し回転床式還元炉で還元処理することができる。
【００４７】
また、上記課題を解決するために、請求項１８に記載の本発明の方法は、請求項１７に記載の本発明において、回転床式還元炉内の温度を１３００℃以下として原料を還元処理することを特徴とする。
【００４８】
上記方法によれば、回転床式還元炉内ガス温度を１３００℃以下の低温度で、かつ回転床式還元炉内滞留時間を短くすることで低還元率還元鉄の製造が可能となる。回転床式還元炉内ガス温度は１２５０℃以下更に１２００℃以下においても本発明の効果を有するが、９００℃以下の温度になれば酸化鉄が還元されないため、９００℃以上には保持する必要がある。
【００４９】
また、上記課題を解決するために、請求項１９に記載の本発明の方法は、請求項１７又は１８に記載の本発明において、前記回転床式還元炉に供給された原料を還元率８０％以下で還元処理することを特徴とする。
【００５０】
上記方法によれば、還元率８０％以下の低還元率で回転床式還元炉を運転することにより、低還元率還元鉄の還元設備と溶解炉を組み合わせた際の総エネルギー効率が良くなり経済的効果を有する。
【００５１】
また、上記課題を解決するために、請求項２０に記載の本発明の方法は、請求項１７乃至１９のいずれかに記載の本発明において、前記回転床式還元炉に供給される塊状原料中の塩基度を０．３以上０．６以下とするように添加配合することを特徴とする。
【００５２】
上記方法によれば、塩基度調整用原料を、前記回転床式還元炉に供給される塊状原料中の塩基度を０．３以上０．６以下とするように原料に添加配合することにより、低還元率時に起こる酸化鉄の相変化による膨れ現象が発生し還元鉄が膨らみクラックを生じることを避けることができる。塩基度は０．３以上０．６以下が有効であるが、０．４以上０．５以下が更により高い効果を示す。
【００５３】
【発明の実施の形態】
以下、本発明に係る実施の形態を図に従って詳細に説明する。図１は本発明の実施の態様に係る回転床式還元炉への原料供給及び回転床式還元炉からの排気フローを、図２は本発明の実施の態様に係る原料配合の成分図を、図３は本発明の実施の態様に係る還元率と耐圧壊強度の関係を、図４は本発明の実施の態様に係るＣＯ比と還元率の関係を、図５は本発明の第２の実施の態様に係る回転床式還元炉への原料供給及び回転床式還元炉からの排気フローを示す。また、図１乃至図６においては、同じ構成の部分には同一の符号を付し、それらについての重複する説明は省略する。
【００５４】
本発明では、被還元体の圧壊強度を高めるために原料中に塩基度調整用原料を配合混入して被還元体の低還元率還元を行う。また、塩基度調整用原料は原料中の塩基度が０．３〜０．６となるように配合混入する。塩基度は０．３以上０．６以下が有効であるが、０．４以上０．５以下が更により高い効果を示す。これは、低還元率還元鉄の製造に際して回転床式還元炉内温度が低下し、かつ滞留時間が短くても、スラグボンドが形成することを目的としている。
【００５５】
また、回転床式還元炉内のＣＯ比を０．２以下、好ましくは０．１以下、さらに好ましくは０．０１以下で運転することを目的としている。ＣＯ比が０．０即ちＣＯが存在しない状態での運転も可能であり、ＣＯの後処理設備が不要となり非常に有効である。回転床式還元炉内温度は１３００℃以下又は１２５０℃以下さらに１２００℃以下でも運転可能であるが、酸化鉄が還元されるには９００℃以上の温度が必要である。
【００５６】
図１において、塩基度調整用原料サイロ４と塩基度調整計量器１４が従来設備に追加して設けられている。さらに、ＣＯ比の設定を確実にかつ容易に実施するために、炉内各所にＣＯ計６１とＣＯ_２計６２を、また排気ダクト４４部にダクト用ＣＯ計６３もしくはダクト用Ｏ_２計６４が設けられている。ダクト用ＣＯ計６３及びダクト用Ｏ_２計６４は共に重複して設けてもよい。
【００５７】
炉内にＣＯ計６１とＣＯ_２計６２を設けることで、ＣＯ燃焼用空気の最適投入量を運転状況に応じて把握することができる。また、排気ダクト４４部にダクト用ＣＯ計６３もしくはダクト用Ｏ_２計６４を設けることで、炉外に排出されるＣＯ量を知ることができるため、計測したＣＯ量もしくはＯ_２量をＣＯ燃焼用空気量にフィードバックして空気供給器４２で供給酸素量を調整し、炉外排出ＣＯ量を確実に管理できる。ダクト用ＣＯ計６３もしくはダクト用Ｏ_２計６４は排気ダクト４４のみならず、回転床式還元炉３０より下流側であれば任意の位置に取り付けることが可能である。
【００５８】
排気ダクト４４系においては従来のような炉外に排出されたＣＯを燃焼させることを目的としたアフターバーナ４８付の水冷ダクト４９の設備を小さくするか省略して構成することができる。本実施の形態では、排ガスダクト４４系は、一次冷却器５７、熱交換器５２、二次冷却器５１を設けて構成し、集塵機５４、排気ファン５５を経て煙突５６から大気中へ排出するように構成している。
【００５９】
塩基度調整計量器１４では原料中の塩基度が０．４〜０．５となるように塩基度調整用原料の投入量を調節するようにしている。塩基度調整計量器１４では、被還元体計量器１１で計量された被還元体原料中のＳｉＯ_２量とＣａＯ量、還元材計量器１２で計量された原料中のＳｉＯ_２量とＣａＯ量、バインダ計量器１３で計量されたバインダ中のＳｉＯ_２量とＣａＯ量を数値信号として取込み、塩基度が０．４〜０．５となるように塩基度調整用原料を計量してミキサ２１に供給する。各計量器１１，１２，１３，１４を通しミキサ２１に供給された被還元体原料、炭材含有原料、バインダ、及び塩基度調整用原料は、水分を加えて混練され、成形機２２により塊状に成形され塊状原料７０となり、乾燥器２３で乾燥された後、原料供給機２４にて回転床式還元炉３０内へ供給される。
【００６０】
被還元体が、低還元率対応の温度、滞留時間で還元されるとき、▲１▼低還元率で金属鉄が少なく金属同士の結合力が弱くなること、▲２▼低還元時に起こる酸化鉄の相変化による膨れ現象が発生し還元鉄が膨らみクラックが生じること、の二つの強度低下要因を塩基度を０．３〜０．６より好ましくは０．４〜０．５に調節する作用で低温度、短滞留時間でもスラグボンドを形成することで還元鉄中の粒子の結合力を高め、還元鉄の圧壊強度を必要な範囲に高く維持できる結果が得られる。
【００６１】
図２において、ケース１は本発明対応の塩基度調整用原料を添加配合する原料配合の一実施の形態、ケース２は塩基度調整用原料を添加しない従来対応の原料配合である。図２中ベントナイト及びＣａ（ＯＨ）_２はバインダ、ＣａＣＯ_３は塩基度調整用原料である。バインダとしてベントナイトとＣａ（ＯＨ）_２、塩基度調整用原料としてＣａＣＯ_３を使用し、鉄鉱石、石炭と共に表示の分量比で配合している。なお、バインダ、塩基度調整用原料の種類は適宜に選択されてよい。
【００６２】
図２の下欄には各原料配合の塩基度を示し、ケース１の配合原料は塩基度が０．４〜０．５の範囲に調節されており、ケース２の配合原料は塩基度が０．１〜０．２程度である。
【００６３】
図２におけるケース１及びケース２の原料配合を使用して実験を行った。実験は、各原料配合毎に含有水分量が１％となるように水を加えて混練し、次いで上記混練体を総水分１０ｗｔ％で造粒し（粒径＝１０〜１２ｍｍφ）、上記造粒体を窒素中で、１２００℃で、６分間保持した後、還元率及び粒体の圧壊強度を測定した。図３は、その実験結果である。
【００６４】
図３において、上記実験では、ケース２の従来型原料配合では、還元率５７．５８％において還元鉄ペレット単位での圧壊強度が１．０６ｋｇ／Ｐであるのに対し、ケース１の原料配合では、ほぼ等しい還元率５６．４７％において還元鉄ペレット単位の圧壊強度が１５．６７ｋｇ／Ｐにまで飛躍的に改善されている。この結果から、低還元率還元鉄の製造にあたって、図２及び図３のケース１で示すように、塩基度調整用原料を原料中塩基度０．４〜０．５の範囲で配合することにより、還元段階でスラグボンドによる大きい結合力を生じさせ、還元鉄の圧壊強度を高められることが明らかである。
【００６５】
次に、配合原料と試験設備を使用して実験を行った。実験は、図３の配合原料に含有水分量が１％となるように水を加えて混練し、次いで上記混練体を総水分１０ｗｔ％で塊状化し、次いで試験設備の炉内ガスＣＯ比を０．０１、０．１、０．２と３段階に設定して乾燥済み塊状原料７０を挿入し、還元率８０％以内対応の回転床式還元炉３０内温度１２００℃と、適切な滞留時間を回転床式還元炉３０の回転速度を回転機４３で制御して保持した後、ＣＯ比毎の還元率を測定した。図４は、その実験結果である。
【００６６】
図４において、上記実験では、ＣＯ比が、０．０１、０．１、０．２と変化しても、還元率は原料成分のばらつき程度の僅かな量しか変動せずほぼ一定に維持されている。これは、塊状原料７０の含有する酸化鉄成分が還元反応中に回転床式還元炉３０内ガス中のＣＯ_２の影響をあまり受けず、すなわち再酸化されずに低還元率対応の回転床式還元炉３０内温度、時間で有効に還元反応が進んでいることを顕している。
【００６７】
この結果から、低還元率還元鉄の還元設備による低還元率での還元鉄の製造にあたって、図４で示すように、回転床式還元炉３０内のガスのＣＯ比制御値を、０．２以下、好ましくは０．１以下、更に好ましくは０．０１以下に設定調節し、回転床式還元炉３０を還元率８０％以下、又は７０％以下、更に６０％以下にも対応の炉内温度、滞留時間に炉操業条件として設定し、塊状原料７０を挿入し還元鉄を排出する方法で、有効に低還元率還元鉄を製造できることが明らかである。
【００６８】
次に、図５により、本発明の第２の実施の形態について説明する。図５は、図１における被還元体サイロ１とミキサ２１との間に設けられた被還元体計量器１１と、還元材サイロ２とミキサ２１との間に設けられた還元材計量器１２と、バインダサイロ３とミキサ２１との間に設けられたバインダ計量器１３との代わりに、ミキサ２１と成形機２２の間に混合原料計量器１５を設けたものである。これによって、原料が混合された後にＳｉＯ_２量とＣａＯ量を計量するので、各原料の混合機に入る前にそれぞれ計量する場合に比較して塩基度の調整精度は劣るものの、計量器の数を少なくすることができる。混合原料計量器１５以外の装置の構成は、図１と同じである。
【００６９】
【発明の効果】
そして上記の結果、前記本発明によれば、次のような作用効果を達成できる。
（１）原料中の塩基度を調整することによって、被還元体の還元温度が１３００℃以下であってもスラグボンドの形成により還元体の圧壊強度を保持できる。
（２）被還元体が低還元率で還元される時に見られる被還元体の膨れ現象による強度低下を、スラグボンドを形成することで抑制できる。
（３）被還元体の圧壊強度が確保できると、炉から排出される時に還元鉄が粉化、破損せず、回転床炉内及び排ガス処理設備でのダスト付着量を低減できる。また、炉外に排出された後の搬送中における還元鉄の粉化、破損を防ぐことができ、歩留まりが向上する。
（４）この結果、還元体の粉化、破損を防止して有効に被還元体を低還元率還元できる還元方法を提供できる。
（５）ＣＯ比制御値を０．２以下とすることにより炉内ガス中に滞留する余分なＣＯが炉内で燃焼し、有効に熱源として働く。そのため、燃料の無駄な消費がなくなり、燃料消費量を低減することができる。
（６）炉内でＣＯを完全燃焼させた場合は、排ガス系設備でのアフターバーナなどの余分なＣＯ対策が不要になり、設備費や維持費が低減される。
（７）経済的で有効な低還元率還元鉄の還元設備と製造方法を提供できる。
【００７０】
更に、上記の効果を達成するために、
請求項１に記載の本発明は、還元鉄の圧壊強度を低下させずに、被還元体を低還元率で製造するための、原料に添加する塩基度調整用原料を保存し供給することができる。
【００７１】
また、請求項２に記載の本発明は、原料に添加する塩基度調整用原料を調整することができる。
【００７２】
また、請求項３に記載の本発明は、原料に添加する塩基度調整用原料を調整し混合機に供給することができる。
【００７３】
また、請求項４に記載の本発明は、原料の混合機に入る前にそれぞれ計量する請求項２に記載の発明の場合に比較して、計量器の数を少なくすることができる。
【００７４】
また、請求項５に記載の本発明は、原料を全て混合機にて混合した後、塩基度調整用原料を調整することができる。
【００７５】
また、請求項６に記載の本発明は、塩基度調整用原料としてＣａ化合物であるＣａＣＯ_３を供給することができる。
【００７６】
また、請求項７に記載の本発明は、計測したＣＯ量及びＣＯ_２量、又はＣＯ比をＣＯ燃焼用空気量にフィードバックし、回転床式還元炉内のＣＯ量を管理できる。
【００７７】
また、請求項８に記載の本発明は、計測したＣＯ量もしくはＯ_２量をＣＯ燃焼用空気量にフィードバックし、回転床式還元炉外排出ＣＯ量を管理できる。
また、請求項９及び１０に記載の本発明は、回転床式還元炉内のＣＯ比を調整することができる。
【００７８】
また、請求項１１に記載の本発明は、炉外に放出する未燃ＣＯを減少させ、また、アフターバーナ付の水冷ダクトで燃焼させる等の余分な設備と処理を縮小させるか又は必要としなくなる。
【００７９】
また、請求項１２及び１３に記載の本発明は、回転床式還元炉内の温度を１３００℃以下の所定の温度に設定することできる。
【００８０】
また、請求項１４に記載の本発明は、石炭直接還元設備と溶解炉を組み合わせた際の総エネルギー効率が良くなり経済的となる。
【００８１】
また、請求項１５に記載の本発明の塊状原料は、塩基度が所定の値に配合された塊状原料を回転床式還元炉に供給することができる。
【００８２】
また、請求項１６に記載の本発明の塊状原料は、塩基度調整用の原料であるＣａ化合物を含有した回転床式還元炉用の塊状原料を供給することができる。
【００８３】
また、請求項１７に記載の本発明の方法は、還元鉄の圧壊強度を低下させずに、被還元体を低還元率で製造し回転床式還元炉で還元処理することができる。
【００８４】
また、請求項１８に記載の本発明の方法は、回転床式還元炉内ガス温度を低温度で、かつ回転床式還元炉内滞留時間を短くすることで低還元率還元鉄の製造が可能となる。
【００８５】
また、請求項１９に記載の本発明の方法は、石炭直接還元設備と溶解炉を組み合わせた際の総エネルギー効率が良くなり経済的となる。
【００８６】
また、請求項２０に記載の本発明の方法は、低還元率時に起こる酸化鉄の相変化による膨れ現象が発生し還元鉄が膨らみクラックを生じることを避けることができる。
【図面の簡単な説明】
【図１】本発明の実施の態様に係る回転床式還元炉への原料供給及び回転床式還元炉からの排気フロー図。
【図２】本発明の実施の態様に係る原料配合の成分図。
【図３】本発明の実施の態様に係る還元率と耐圧壊強度の関係図。
【図４】本発明の実施の態様に係るＣＯ比と還元率の関係図。
【図５】本発明の第２の実施の態様に係る回転床式還元炉への原料供給及び回転床式還元炉からの排気フロー図。
【図６】従来の回転床式還元炉への原料供給及び回転床式還元炉からの排気フロー図。
【符号の説明】
１…被還元体サイロ
２…還元材サイロ
３…バインダサイロ
４…塩基度調整サイロ
１１…被還元体計量器
１２…還元材計量器
１３…バインダ計量器
１４…塩基度調整計量器
１５…混合原料計量器
２１…ミキサ
２２…成形機
２３…乾燥器
２４…原料供給機
３０…回転床式還元炉
４１…熱ガスバーナ
４２…空気供給器
４３…回転機
４４…排気ダクト
６１…ＣＯ計
６２…ＣＯ_２計
６３…ダクト用ＣＯ計
６４…ダクト用Ｏ_２計
６５…温度計
７０…塊状原料[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a low-reduction-rate reduced iron reduction facility and a reduction method for reducing iron oxide.
[0002]
[Prior art]
FIG. 6 is a flow chart showing the supply of raw materials to a rotary bed type reduction furnace, which is a conventional reduction facility, and the exhaust flow from the rotary bed type reduction furnace.
[0003]
The material to be reduced, which is an iron source of reduced iron mainly composed of iron oxide, which is a raw material for the production of reduced iron, a carbon material-containing material including a carbon material as a reducing material, and a binder as a binder are individual silos. That is, it is supplied from the reduction object silo 1, the reducing material silo 2, and the binder silo 3, respectively. The reduced material raw material supplied from the reduced material silo 1 is dried in the reduced material drying device 5 and then crushed and classified by the reduced material crusher 6 and the reduced material classifier 7. On the other hand, the carbon material-containing material supplied from the reducing material silo 2 is crushed and classified by the reducing material crusher 8 and the reducing material classifier 9.
[0004]
The raw material to be reduced classified by the reduced material classifier 7 is supplied from the binder silo 3 by the reduced material measuring device 11, and the carbon material-containing material classified by the reducing material classifier 9 is supplied by the reducing material measuring device 12. The binder is measured by a predetermined amount by the binder measuring device 13 and sent to the mixer 21 where it is kneaded with a necessary water content. The raw material kneaded by the mixer 21 is sent to a molding machine 22, formed into a bulk raw material 70 such as pellets or briquettes under a required amount of water, and dried by a dryer 23. It is supplied into the type reduction furnace 30 (for example, see Patent Document 1).
[0005]
The rotary bed type reduction furnace 30 includes a plurality of hot gas burners 41 for generating hot gas used for reduction in the furnace, an exhaust duct 44 for exhausting the used hot gas, and an exhaust unit 45 for discharging reduced pellets. And a plurality of air feeders 42 with flow rate adjusting means 46 for adjusting the CO ratio in the furnace. In the rotary bed type reduction furnace 30, fuel and combustion air are supplied to the hot gas burner 41 and burned, and the inside of the rotary bed type reduction furnace 30 is maintained at a high temperature (1300 to 1400 ° C.) and supplied while the rotary bed makes one round. The lump raw material 70 is heated to about 1300 ° C. and reduced to be reduced iron. The reduced raw material 70 is taken out of the rotary bed type reduction furnace 30 into the portable container 47 and sent to the next step. The temperature in the rotary bed type reduction furnace 30 is measured by a thermometer 65 installed in the rotary bed type reduction furnace 30. The rotation speed of the rotating bed is controlled by a rotating machine (not shown) provided in the rotating bed type reduction furnace 30.
[0006]
The hot gas that escapes to the exhaust duct 44 burns and cools unburned gas components in a water cooling duct 49 with an afterburner 48, and is further cooled by a secondary cooler 51, a heat exchanger 52, a tertiary cooler 53, and the like. Then, the air is discharged from the chimney 56 to the atmosphere via the dust collector 54 and the exhaust fan 55 (for example, see Patent Document 2).
[0007]
Conventionally, such a low-reduction-rate reduced iron reduction facility has conventionally aimed at increasing the reduction rate of reduced iron, and generally reduced the reduction rate to more than 80%. In order to obtain such a high reduction rate, it is necessary to raise the temperature of the bulk raw material 70 to about 1300 ° C. and further prolong the residence time in the rotary bed type reduction furnace 30. However, when the residence time in the rotary bed type reduction furnace 30 becomes longer, the reduced iron once reduced becomes CO 2 in the gas in the rotary bed type reduction furnace 30. ₂ May be oxidized again. Therefore, in order to prevent the reoxidation of the reduced iron, CO and CO in the gas in the rotary bed type reduction furnace 30 are reduced. ₂ Ratio [(CO / (CO + CO ₂ )) This is hereinafter referred to as the CO ratio] is maintained at 0.2 or more. Specifically, it is maintained by controlling and adjusting the input amount of CO combustion air by an air supply device 42 provided on the side wall of the rotary bed type reduction furnace 30.
[0008]
That is, in the reduction of reduced iron by the above-described equipment, the CO ratio of the gas in the rotary bed type reduction furnace 30 is adjusted to 0.2 or more, and the furnace temperature (1300 to 1400 ° C.) corresponding to a reduction rate of more than 80%; Furnace operation conditions are set during the residence time, the reduced material is generated at a high temperature by supplying the lump material 70, and the reduction is performed in a step of discharging the reduced iron.
[0009]
For this reason, in the conventional equipment, unburned CO equivalent to a CO ratio (0.2 or more) is released outside the furnace, and the unburned CO cannot be fully utilized as an effective heat source. Unburned CO that has escaped from the rotary bed reduction furnace 30 to the exhaust duct 44 requires extra facilities and treatment, such as burning it in a water-cooled duct 49 with an afterburner 48.
[0010]
In addition, the reduced iron taken out is increased to a region where the reduction ratio exceeds 80%, so that the formation of slag bonds generated due to bonding between reduced metal irons and holding at a high temperature occurs inside the reduced iron, The crushing strength of reduced iron has been maintained. Furthermore, the reduced iron produced in this low-reduction-rate reduced iron reduction facility is intended to be melted in a melting furnace in a subsequent process to obtain pig iron, and the reduction rate of reduced iron is generally considered to be more than 80%. I was
[0011]
However, in recent years, depending on the type of melting furnace, a low reduction rate of 80% or less reduces the total energy efficiency when the reduction equipment of the reduced reduction rate reduced iron and the melting furnace are combined, and is economical. It is said that it is. In order to reduce reduced iron at a low reduction rate of 80% or less, in a conventional low reduction rate reduced iron reduction facility as shown in FIG. 6, for example, the gas temperature in a rotary bed type reduction furnace 30 is 1300 ° C. or less. It has been studied to produce low-reduced reduced iron at a relatively low temperature and by reducing the residence time in the rotary bed-type reduction furnace 30.
[0012]
[Patent Document 1]
JP-A-2000-273552 (FIG. 1).
[Patent Document 2]
JP-A-11-129806 (FIG. 1).
[0013]
[Problems to be solved by the invention]
However, if the production of reduced-reduced reduced iron is simply performed by changing the temperature in the rotary bed type reduction furnace, shortening the residence time, etc., (1) the reduced metallic iron is reduced due to the low reduction rate and is bound. (2) Low temperature inside the rotary bed type reduction furnace and short residence time, making it difficult to form slag bonds. (3) Reduced iron due to swelling due to iron oxide phase change occurring at low reduction rate. For example, the crushing strength of the reduced iron becomes weak due to swelling and cracks, and the following problems occur.
(1) When the reduced iron is discharged from the rotary bed type reduction furnace, it is broken and damaged, and it becomes difficult to discharge the reduced iron from the rotary bed type reduction furnace.
(2) Part of the reduced iron that has been dispersed and destroyed during discharge floats in the gas in the rotary bed type reduction furnace as dust and adheres to the inner wall of the rotary bed type reduction furnace and the exhaust gas equipment duct wall.
(3) Reduced iron discharged from the rotary bed type reduction furnace is crushed and broken during transportation, generating dust.
Furthermore, the operating conditions relating to the CO ratio in the rotary bed type reduction furnace when producing low reduction ratio reduced iron have not yet been elucidated.
[0014]
In order to solve the conventional problem, the present invention sets the CO ratio in the furnace related to the production of an efficient low reduction rate reduced iron without reducing the crushing strength of the reduced iron, and reduces the reduction target in a low reduction rate. It is an object of the present invention to provide a low-reduction rate reduced iron reduction facility and a reduction method that can be produced by the method described above.
[0015]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention according to claim 1 provides a reduced-substance silo for storing a reduced-substance raw material serving as an iron source of reduced iron mainly composed of iron oxide, and a carbon material serving as a reducing material. A raw material supply means including a reducing material silo for storing a carbonaceous material-containing raw material, and a binder silo for storing a binder serving as a caking raw material, and a rotary bed reduction furnace for reducing the iron oxide with a hot gas. A mixer for mixing a plurality of raw materials supplied from the raw material supply unit, a forming unit for forming the raw materials mixed by the mixer, and a drying unit for drying the raw material formed by the forming unit; A feed unit that supplies the raw material dried by the drying unit to the rotary bed type reduction furnace; and an exhaust duct that exhausts the hot gas from the rotary bed type reduction furnace. In the reduction facility of reduced iron, Serial raw material supply means, characterized by comprising a basicity adjustment silo for storing the basicity adjusting material for adjusting the basicity.
[0016]
According to the above configuration, it is possible to store and supply the basicity adjusting raw material to be added to the raw material for producing the reduced body at a low reduction rate without reducing the crushing strength of the reduced iron.
[0017]
In order to solve the above-mentioned problem, the present invention according to claim 2 is the invention according to claim 1, wherein the material to be reduced in the material to be reduced is located between the silo to be reduced and the mixer. SiO ₂ A reducing object measuring device for measuring the amount of CaO and the amount of CaO, wherein the SiO 2 in the carbonaceous material-containing raw material is provided between the reducing material silo and the mixer. ₂ A reducing agent measuring device for measuring the amount of CaO and the amount of CaO, wherein SiO in the binder is provided between the binder silo and the mixer. ₂ A binder measuring device for measuring the amount and the CaO amount is provided, and a basicity adjusting measuring device is provided between the basicity adjusting silo and the mixer.
[0018]
According to the above configuration, the SiO 2 in the material to be reduced, the carbonaceous material-containing material, and the binder are used. ₂ The amount of CaO and the amount of CaO were measured, and the basicity (CaO / SiO ₂ In order to set the ratio) to a predetermined value, the basicity adjusting raw material to be added to each of the above raw materials can be adjusted by a basicity adjusting meter. SiO in the material to be reduced, in the carbonaceous material-containing material and in the binder ₂ Each measuring device for measuring the amount and the amount of CaO ₂ It is needless to say that the present invention can be constituted by a plurality of measuring devices for individually measuring the amount and the CaO amount, respectively.
[0019]
In order to solve the above problem, the present invention according to claim 3 is directed to a method according to claim 2, wherein the SiO 2 in the material to be reduced is measured by the device to be reduced. ₂ Amount, CaO amount, and SiO in the carbonaceous material-containing raw material measured by the reducing agent measuring device. ₂ Amount, CaO amount, and SiO in the binder measured by the binder measuring device. ₂ Based on the amount and the amount of CaO, the basicity adjustment measuring device adjusts the basicity adjusting raw material to the mixer so that the basicity of the raw material supplied to the mixer is 0.3 to 0.6. Characterized in that it is configured to be supplied to
[0020]
According to the above configuration, the SiO 2 in the material to be reduced, the carbonaceous material-containing material, and the binder are used. ₂ The amount of CaO and the amount of CaO were measured, and the basicity (CaO / SiO ₂ The basicity-adjusting raw material to be added to each of the above-mentioned raw materials can be adjusted by a basicity-adjusting meter and supplied to the mixer such that the ratio) becomes an effective value of 0.3 or more and 0.6 or less. The basicity is effective when the basicity is 0.3 or more and 0.6 or less.
[0021]
According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, in the first aspect of the present invention, SiO 2 in the mixed raw material is disposed between the mixer and the molding means. ₂ A mixed raw material measuring device for measuring the amount and the CaO amount, and a basicity adjusting measuring device provided between the basicity adjusting silo and the mixer.
[0022]
According to the above configuration, after all the raw materials are mixed by the mixer, the SiO 2 in the mixed raw materials is mixed. ₂ The amount and CaO amount are measured, and the raw material for basicity adjustment is adjusted by the basicity adjusting measuring instrument based on the measured value. Although the adjustment accuracy is inferior, the number of measuring instruments can be reduced. SiO in the mixed raw material ₂ Raw material meter for measuring the amount of CaO and CaO ₂ It goes without saying that it is within the scope of the present invention to constitute a plurality of measuring devices for individually measuring the amount and the CaO amount.
[0023]
According to a fifth aspect of the present invention, in order to solve the above-mentioned problem, in the present invention according to the fourth aspect, SiO 2 in the mixed raw material measured by the mixed raw material measuring device is measured. ₂ Based on the amount and the amount of CaO, the basicity-adjusting measuring device sends the basicity-adjusting raw material to the mixer so that the basicity of the raw material supplied to the mixer is 0.3 or more and 0.6 or less. It is characterized in that it is configured to supply.
[0024]
According to the above configuration, after all the raw materials are mixed by the mixer, the mixed raw material SiO ₂ The amount of CaO and the amount of CaO are weighed, and the raw material for adjusting the basicity is adjusted by a basicity adjusting meter and supplied to a mixer to obtain a basicity (CaO / SiO2). ₂ Ratio) can be adjusted so as to be an effective value of 0.3 or more and 0.6 or less. The basicity is effective when the basicity is 0.3 or more and 0.6 or less.
[0025]
In order to solve the above problem, the present invention according to claim 6 is characterized in that, in the present invention according to any one of claims 1 to 5, the raw material for adjusting basicity contains a Ca compound. And
[0026]
According to the above configuration, for example, CaCO ₃ Can be supplied. The basicity adjusting raw material is basicity (CaO / SiO ₂ Ratio) can be adjusted. ₃ It goes without saying that the present invention is within the scope of the present invention as long as the basicity can be adjusted even if other Ca compounds are appropriately selected.
[0027]
Further, in order to solve the above-mentioned problem, the present invention according to claim 7 is directed to a method according to any one of claims 1 to 6, wherein the rotary bed type reduction furnace is configured to measure carbon monoxide concentration. Measuring instrument and CO for measuring carbon dioxide concentration ₂ And a measuring device.
[0028]
According to the above configuration, by measuring the carbon monoxide concentration and the carbon dioxide concentration, the CO ratio (CO / (CO + CO ₂ )). Measured CO amount and CO ₂ The amount or CO ratio can be fed back to the amount of CO combustion air to control the amount of CO in the rotary bed type reduction furnace.
[0029]
In order to solve the above-mentioned problem, the present invention according to claim 8 is the invention according to claim 7, wherein the exhaust duct has at least a carbon monoxide measuring device for measuring carbon monoxide concentration or an oxygen concentration. O for measuring duct ₂ It is characterized by having a measuring instrument.
[0030]
According to the above configuration, a CO measuring instrument or O ₂ By providing a measuring device, the amount of CO discharged to the outside of the rotary bed type reduction furnace can be known. ₂ The amount can be fed back to the amount of CO combustion air to control the amount of CO discharged from the rotary bed type reduction furnace.
[0031]
According to a ninth aspect of the present invention, in order to solve the above problem, in the present invention according to any one of the first to eighth aspects, the rotary bed type reduction furnace supplies a fluid containing oxygen. It is characterized by comprising a plurality of fluid supply means.
[0032]
According to a tenth aspect of the present invention, in order to solve the above problem, in the ninth aspect of the present invention, the oxygen-containing fluid is air or an oxygen-enriched gas containing oxygen. It is characterized by the following.
[0033]
According to the configuration of claims 9 and 10, CO in the rotary bed type reduction furnace is oxidized with oxygen to reduce CO2. ₂ By doing so, the CO ratio in the rotary bed type reduction furnace can be adjusted.
[0034]
Further, in order to solve the above-mentioned problem, the present invention according to claim 11 is the present invention according to claim 9 or 10, wherein the fluid supply means is provided so that the CO ratio becomes 0.2 or less. A fluid control means for adjusting the amount is provided.
[0035]
According to the above configuration, compared to the conventional CO ratio of 0.2 or more, extra equipment and processing such as reducing unburned CO emitted outside the furnace and burning it with a water-cooled duct with an afterburner are required. Reduced or no longer needed. The CO ratio is 0.2 or less, but preferably 0.1 or less, more preferably 0.01 or less is effective in that unnecessary CO is not used, and the use of CO-free gas is more effective. It is.
[0036]
According to a twelfth aspect of the present invention, in order to solve the above-described problem, in the first to eleventh aspects of the present invention, the rotary bed-type reduction furnace measures a temperature in the furnace. And a plurality of hot gas burners for generating hot gas in the furnace.
[0037]
In order to solve the above problem, the present invention according to claim 13 is the invention according to claim 12, wherein the hot gas burner is adjusted such that the temperature indicated by the temperature measuring device is 1300 ° C. or less. And a hot gas burner adjusting means.
[0038]
According to the configuration of the twelfth and thirteenth aspects, the temperature in the rotary bed type reduction furnace is measured, and the temperature can be set to a predetermined temperature of 1300 ° C. or less. The effect of the present invention can be obtained even when the temperature in the rotary bed type reduction furnace is 1250 ° C. or lower and further 1200 ° C. or lower. However, when the temperature is 900 ° C. or lower, iron oxide is not reduced. There is.
[0039]
In order to solve the above-mentioned problem, the present invention described in claim 14 is the invention according to any one of claims 1 to 13, wherein the rotation of the iron oxide is reduced so that the reduction ratio of iron oxide is 80% or less. A rotating means capable of adjusting the rotating speed of the bed type reduction furnace is provided.
[0040]
According to the above configuration, the rotating speed of the rotary bed-type reduction furnace is adjusted to operate the rotary bed-type reduction furnace at a low reduction rate of 80% or less, so that the low-reduction-rate reduced iron reduction equipment and melting furnace The total energy efficiency when combining is improved and becomes economical.
[0041]
Further, in order to solve the above problem, the bulk raw material of the present invention according to claim 15 is a reduced material raw material that is an iron source of reduced iron, a carbon material-containing raw material containing a carbon material that is a reducing material, It is characterized in that it contains a binder serving as a caking raw material and a raw material for adjusting basicity for adjusting basicity, and is blended so that the basicity is 0.3 or more and 0.6 or less.
[0042]
According to the above configuration, a material to be reduced to be an iron source of reduced iron, a carbon material-containing material including a carbon material to be a reducing material, a binder to be a binding material, and a basicity for adjusting the basicity The raw material for adjustment and the raw material mixed so that the basicity is 0.3 or more and 0.6 or less can be supplied to the rotary bed type reduction furnace. The basicity is effective when the basicity is 0.3 or more and 0.6 or less.
[0043]
In order to solve the above problems, the bulk raw material of the present invention according to claim 16 is characterized in that, in the present invention according to claim 15, the basicity adjusting raw material contains a Ca compound. .
[0044]
According to the above configuration, for example, the basicity adjusting raw material CaCO ₃ Can be supplied for the rotary bed type reduction furnace. The basicity adjusting raw material only needs to be able to adjust the basicity. ₃ It goes without saying that the present invention is within the scope of the present invention as long as the basicity can be adjusted even if other Ca compounds are appropriately selected.
[0045]
In order to solve the above-mentioned problems, a method of the present invention according to claim 17 is characterized in that a material to be reduced that is an iron source of reduced iron, a carbon material-containing raw material containing a carbon material that is a reducing material, It is characterized in that a lump material containing a binder as a binding material and a material for adjusting basicity for adjusting the basicity is subjected to reduction treatment in a rotary bed type reduction furnace.
[0046]
According to the above method, using a bulk raw material containing a basicity adjusting raw material as a raw material, without reducing the crushing strength of reduced iron, producing a reduced body at a low reduction rate, and reducing it in a rotary bed type reduction furnace. Can be processed.
[0047]
In order to solve the above-mentioned problems, a method according to the present invention as set forth in claim 18, according to the present invention as set forth in claim 17, reduces the temperature of the raw material in the rotary bed-type reduction furnace to 1300 ° C or less. It is characterized by the following.
[0048]
According to the above method, low-reduced-rate reduced iron can be produced by keeping the gas temperature in the rotary bed type reduction furnace at a low temperature of 1300 ° C. or less and shortening the residence time in the rotary bed type reduction furnace. The effect of the present invention can be obtained even when the gas temperature in the rotary bed type reduction furnace is 1250 ° C. or less and further 1200 ° C. or less. However, when the temperature is 900 ° C. or less, iron oxide is not reduced. is there.
[0049]
In order to solve the above-mentioned problem, a method according to the present invention according to claim 19 is the method according to claim 17 or 18, wherein the raw material supplied to the rotary bed type reduction furnace has a reduction rate of 80%. In the following, a reduction process is performed.
[0050]
According to the above method, by operating the rotary bed type reduction furnace at a low reduction rate of 80% or less, the total energy efficiency when the reduction equipment of the low reduction rate reduced iron is combined with the melting furnace is improved, and the economy is improved. Has a positive effect.
[0051]
In order to solve the above-mentioned problems, a method according to the present invention described in claim 20 is the method according to any one of claims 17 to 19, wherein the bulk raw material supplied to the rotary bed reduction furnace is used. Is characterized by being added and blended so that the basicity is 0.3 or more and 0.6 or less.
[0052]
According to the above method, by adding and blending the basicity adjusting raw material to the raw material so that the basicity in the bulk raw material supplied to the rotary bed reduction furnace is 0.3 or more and 0.6 or less, It is possible to avoid the occurrence of a swelling phenomenon due to the phase change of the iron oxide occurring at the time of the low reduction rate, and the swelling of the reduced iron to cause a crack. The basicity is effective when the basicity is 0.3 or more and 0.6 or less.
[0053]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows a raw material supply to a rotary bed type reduction furnace according to an embodiment of the present invention and an exhaust flow from the rotary bed type reduction furnace, and FIG. 2 shows a component diagram of a raw material mixture according to an embodiment of the present invention. 3 shows the relationship between the reduction ratio and the compressive strength according to the embodiment of the present invention, FIG. 4 shows the relationship between the CO ratio and the reduction ratio according to the embodiment of the present invention, and FIG. 3 shows a raw material supply to a rotary bed type reduction furnace and an exhaust flow from the rotary bed type reduction furnace according to the embodiment. 1 to 6, the same components are denoted by the same reference numerals, and redundant description thereof will be omitted.
[0054]
In the present invention, in order to increase the crushing strength of the reduced material, a raw material for adjusting the basicity is mixed and mixed into the raw material, and the reduced material is reduced at a low reduction rate. The basicity adjusting raw material is mixed and mixed so that the basicity in the raw material is 0.3 to 0.6. The basicity is effective when the basicity is 0.3 or more and 0.6 or less. The purpose of this is to form slag bonds even when the temperature in the rotary bed type reduction furnace is reduced and the residence time is short in the production of low reduction ratio reduced iron.
[0055]
It is another object of the present invention to operate at a CO ratio of 0.2 or less, preferably 0.1 or less, more preferably 0.01 or less in a rotary bed type reduction furnace. It is also possible to operate in a state where the CO ratio is 0.0, that is, in a state where CO is not present, and the CO post-processing equipment is not required, which is very effective. The operation can be performed at a temperature of 1300 ° C. or lower, 1250 ° C. or lower, and 1200 ° C. or lower, but a temperature of 900 ° C. or higher is required for reducing iron oxide.
[0056]
In FIG. 1, a basicity adjusting raw material silo 4 and a basicity adjusting measuring device 14 are provided in addition to conventional equipment. Further, in order to set the CO ratio reliably and easily, the CO meter 61 and CO ₂ 62, and a duct CO meter 63 or a duct O ₂ A total of 64 are provided. CO total 63 for duct and O for duct ₂ The total 64 may be provided in duplicate.
[0057]
CO meter 61 and CO in furnace ₂ By providing the total 62, the optimum input amount of the CO combustion air can be grasped in accordance with the operation situation. Also, a duct CO meter 63 or a duct O ₂ By providing the total 64, it is possible to know the amount of CO discharged outside the furnace. ₂ The amount is fed back to the CO combustion air amount, the supplied oxygen amount is adjusted by the air supply unit 42, and the CO emission amount outside the furnace can be reliably managed. CO total 63 for duct or O for duct ₂ The total 64 can be attached not only to the exhaust duct 44 but also to any position on the downstream side of the rotary bed type reduction furnace 30.
[0058]
In the exhaust duct 44 system, the equipment of the water cooling duct 49 with the afterburner 48 for the purpose of burning the CO discharged outside the furnace as in the related art can be reduced or omitted. In this embodiment, the exhaust gas duct 44 system is provided with a primary cooler 57, a heat exchanger 52, and a secondary cooler 51, and is discharged from a chimney 56 to the atmosphere via a dust collector 54 and an exhaust fan 55. It is composed.
[0059]
The basicity adjusting measuring device 14 adjusts the input amount of the basicity adjusting raw material so that the basicity in the raw material becomes 0.4 to 0.5. In the basicity adjusting measuring device 14, the SiO 2 in the material to be reduced measured by the measuring device 11 for reduced object ₂ Amount and CaO amount, SiO in the raw material measured by the reducing material measuring device 12 ₂ Amount and CaO amount, SiO in the binder measured by the binder measuring device 13 ₂ The amount and the amount of CaO are taken in as a numerical signal, and the basicity adjusting raw material is measured and supplied to the mixer 21 so that the basicity becomes 0.4 to 0.5. The raw material to be reduced, the raw material containing carbonaceous material, the binder, and the raw material for adjusting the basicity supplied to the mixer 21 through the measuring devices 11, 12, 13, and 14 are kneaded by adding moisture, and are massed by the molding machine 22. After being formed into a bulk material 70 and dried by the dryer 23, the raw material is supplied into the rotary bed type reduction furnace 30 by the raw material supply device 24.
[0060]
When the object to be reduced is reduced at a temperature and a residence time corresponding to a low reduction rate, (1) a low reduction rate, a small amount of metallic iron and a weak bonding force between metals, and (2) an iron oxide generated at a low reduction rate The swelling phenomenon due to the phase change occurs and the reduced iron swells and cracks are caused by the action of adjusting the basicity to 0.3 to 0.6, more preferably 0.4 to 0.5. Forming a slag bond even at a low temperature and a short residence time enhances the bonding force of the particles in the reduced iron, thereby obtaining a result in which the crushing strength of the reduced iron can be maintained at a high level within a required range.
[0061]
In FIG. 2, Case 1 is an embodiment of a raw material blend in which a basicity adjusting raw material according to the present invention is added and blended, and Case 2 is a conventional raw material blend in which no basicity adjusting raw material is added. Bentonite and Ca (OH) in FIG. ₂ Is a binder, CaCO ₃ Is a raw material for adjusting basicity. Bentonite and Ca (OH) as binder ₂ , CaCO as a raw material for adjusting basicity ₃ And is blended with iron ore and coal at the indicated proportions. Note that the types of the binder and the basicity adjusting raw material may be appropriately selected.
[0062]
The lower column in FIG. 2 shows the basicity of each raw material blend. The blended raw material in Case 1 is adjusted to have a basicity of 0.4 to 0.5, and the blended raw material in Case 2 has a basicity of 0. About 0.1 to 0.2.
[0063]
An experiment was performed using the raw material formulations of Case 1 and Case 2 in FIG. In the experiment, water was added and kneaded so that the water content became 1% for each raw material mixture, and then the kneaded body was granulated with a total water content of 10 wt% (particle size = 10 to 12 mmφ). After keeping the body in nitrogen at 1200 ° C. for 6 minutes, the reduction ratio and the crushing strength of the granules were measured. FIG. 3 shows the result of the experiment.
[0064]
In FIG. 3, in the above experiment, the crushing strength of the reduced iron pellet unit in the conventional material blend of Case 2 was 1.06 kg / P at the reduction ratio of 57.58%, whereas The crushing strength of the reduced iron pellet unit at a substantially equal reduction rate of 56.47% is dramatically improved to 15.67 kg / P. From these results, in the production of reduced iron with a low reduction rate, as shown in Case 1 of FIGS. 2 and 3, the raw material for adjusting basicity is blended in a range of basicity of 0.4 to 0.5 in the raw material. It is evident that a large bonding force due to slag bond is generated in the reduction step, and the crushing strength of the reduced iron can be increased.
[0065]
Next, an experiment was performed using the blended raw materials and test equipment. In the experiment, water was added to the blended raw material shown in FIG. 3 so that the water content was 1%, and the mixture was kneaded. Then, the above kneaded material was agglomerated with a total moisture of 10 wt%, and then the gas CO ratio in the furnace of the test facility was reduced to 0%. .01, 0.1, 0.2 and three stages, the dried bulk material 70 is inserted, and the temperature inside the rotary bed type reduction furnace 30 corresponding to a reduction rate of 80% or less and 1200 ° C., and an appropriate residence time are set. After the rotation speed of the rotary bed type reduction furnace 30 was controlled and held by the rotating machine 43, the reduction rate for each CO ratio was measured. FIG. 4 shows the results of the experiment.
[0066]
In FIG. 4, in the above experiment, even if the CO ratio changes to 0.01, 0.1, and 0.2, the reduction ratio fluctuates only by a small amount of the degree of variation of the raw material components, and is maintained almost constant. ing. This is because the iron oxide component contained in the bulk raw material 70 contains CO 2 in the gas in the rotary bed type reduction furnace 30 during the reduction reaction. ₂ That is, the reduction reaction is effectively progressed at a temperature and time in the rotary bed type reduction furnace 30 corresponding to a low reduction rate without being re-oxidized.
[0067]
From this result, as shown in FIG. 4, when producing reduced iron at a low reduction rate by a reduction facility for low reduction rate reduced iron, the CO ratio control value of the gas in the rotary bed type reduction furnace 30 was set to 0.2. The temperature is adjusted to be not more than 0.1, more preferably not more than 0.1, and more preferably not more than 0.01. It is apparent that low-rate reduced iron can be produced effectively by a method in which the residence time is set as the furnace operation condition, the massive raw material 70 is inserted and the reduced iron is discharged.
[0068]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a reduced object measuring device 11 provided between the reduced object silo 1 and the mixer 21 in FIG. 1 and a reduced material measuring device 12 provided between the reducing material silo 2 and the mixer 21. Instead of the binder measuring device 13 provided between the binder silo 3 and the mixer 21, a mixed raw material measuring device 15 is provided between the mixer 21 and the molding machine 22. Thereby, after the raw materials are mixed, the SiO 2 ₂ Since the amount and the CaO amount are measured, the accuracy of adjusting the basicity is inferior to the case where each raw material is measured before entering the mixer, but the number of measuring devices can be reduced. The configuration of the device other than the mixed raw material measuring device 15 is the same as that of FIG.
[0069]
【The invention's effect】
As a result, according to the present invention, the following operation and effect can be achieved.
(1) By adjusting the basicity in the raw material, the crushing strength of the reduced body can be maintained by forming slag bonds even if the reduction temperature of the reduced body is 1300 ° C. or less.
(2) The reduction in strength due to the swelling phenomenon of the reduced object, which is observed when the reduced object is reduced at a low reduction rate, can be suppressed by forming a slag bond.
(3) If the crushing strength of the object to be reduced can be ensured, the reduced iron will not be powdered and damaged when discharged from the furnace, and the amount of dust attached in the rotary bed furnace and the exhaust gas treatment facility can be reduced. In addition, it is possible to prevent the reduced iron from being powdered and damaged during transportation after being discharged from the furnace, and to improve the yield.
(4) As a result, it is possible to provide a reduction method capable of preventing the reduced body from being powdered or damaged and effectively reducing the reduced body at a low reduction rate.
(5) By setting the CO ratio control value to 0.2 or less, excess CO staying in the furnace gas is burned in the furnace and effectively functions as a heat source. Therefore, wasteful consumption of fuel is eliminated, and fuel consumption can be reduced.
(6) When CO is completely burned in the furnace, extra CO measures such as an afterburner in the exhaust gas system become unnecessary, and the equipment cost and the maintenance cost are reduced.
(7) It is possible to provide an economical and effective equipment for reducing reduced iron and a method for producing reduced iron.
[0070]
Furthermore, in order to achieve the above effects,
According to the first aspect of the present invention, it is possible to store and supply a basicity adjusting raw material to be added to a raw material for producing a reduced body at a low reduction rate without reducing the crushing strength of reduced iron. it can.
[0071]
Further, according to the second aspect of the present invention, a basicity adjusting raw material to be added to the raw material can be adjusted.
[0072]
Further, according to the third aspect of the present invention, the basicity adjusting raw material to be added to the raw material can be adjusted and supplied to the mixer.
[0073]
Further, according to the present invention described in claim 4, the number of measuring instruments can be reduced as compared with the case of the invention described in claim 2 in which each of the raw materials is measured before entering the mixer.
[0074]
Further, according to the present invention as set forth in claim 5, the raw material for adjusting the basicity can be adjusted after all the raw materials are mixed by a mixer.
[0075]
Further, the present invention according to claim 6 provides a Ca compound which is a Ca compound as a raw material for adjusting basicity. ₃ Can be supplied.
[0076]
Further, according to the present invention, the measured amount of CO and CO ₂ The amount or CO ratio can be fed back to the amount of CO combustion air to control the amount of CO in the rotary bed type reduction furnace.
[0077]
Further, the present invention according to claim 8 is characterized in that the measured amount of CO or O ₂ The amount can be fed back to the amount of CO combustion air to control the amount of CO discharged from the rotary bed type reduction furnace.
The present invention described in claims 9 and 10 can adjust the CO ratio in the rotary bed type reduction furnace.
[0078]
In addition, the present invention according to claim 11 reduces or eliminates the need for extra equipment and processing, such as reducing unburned CO emitted outside the furnace and burning it in a water-cooled duct with an afterburner. .
[0079]
Further, according to the present invention described in claims 12 and 13, the temperature inside the rotary bed type reduction furnace can be set to a predetermined temperature of 1300 ° C. or less.
[0080]
Moreover, the present invention described in claim 14 improves the total energy efficiency when the direct coal reduction facility and the melting furnace are combined, and is economical.
[0081]
In addition, the bulk raw material of the present invention described in claim 15 can supply a bulk raw material whose basicity is blended to a predetermined value to a rotary bed reduction furnace.
[0082]
Further, the bulk raw material of the present invention described in claim 16 can supply a bulk raw material for a rotary bed reduction furnace containing a Ca compound which is a raw material for adjusting basicity.
[0083]
According to the method of the present invention described in claim 17, the object to be reduced can be produced at a low reduction rate and reduced in a rotary bed type reduction furnace without reducing the crushing strength of the reduced iron.
[0084]
Further, the method of the present invention according to claim 18 enables the production of reduced iron with a low reduction rate by reducing the gas temperature in the rotary bed type reduction furnace and shortening the residence time in the rotary bed type reduction furnace. It becomes.
[0085]
The method of the present invention described in claim 19 is economical because the total energy efficiency when the coal direct reduction facility and the melting furnace are combined is improved.
[0086]
Further, the method of the present invention described in claim 20 can avoid the occurrence of a swelling phenomenon due to a phase change of iron oxide occurring at a low reduction rate, thereby causing the reduced iron to swell and cause cracks.
[Brief description of the drawings]
FIG. 1 is a flow chart showing the supply of raw materials to a rotary bed type reduction furnace and the exhaust flow from the rotary bed type reduction furnace according to an embodiment of the present invention.
FIG. 2 is a component diagram of a raw material blend according to an embodiment of the present invention.
FIG. 3 is a diagram showing the relationship between the reduction ratio and the compressive strength according to the embodiment of the present invention.
FIG. 4 is a relationship diagram between a CO ratio and a reduction rate according to the embodiment of the present invention.
FIG. 5 is a flow chart showing a supply of raw materials to a rotary bed type reduction furnace and an exhaust flow from the rotary bed type reduction furnace according to a second embodiment of the present invention.
FIG. 6 is a flow chart showing the supply of raw materials to a conventional rotary bed type reduction furnace and the exhaust flow from the rotary bed type reduction furnace.
[Explanation of symbols]
1 ... Reduced object silo
2. Reduction material silo
3. Binder silo
4. Basicity adjustment silo
11 ... Reduced object measuring instrument
12 ... Reducing material meter
13. Binder weigher
14. Basicity adjustment meter
15: Mixed raw material measuring instrument
21 ... Mixer
22 molding machine
23 ... Dryer
24 Raw material supply machine
30 ... Rotary bed type reduction furnace
41 ... Hot gas burner
42 ... Air supply device
43 ... Rotating machine
44… Exhaust duct
61 ... CO meter
62 ... CO ₂ Total
63… CO meter for duct
64 ... O for duct ₂ Total
65 ... thermometer
70 ... Lump raw material

Claims

A reduced-substance silo that stores a reduced-substance raw material that is an iron source of reduced iron mainly composed of iron oxide, a reducing-material silo that stores a carbon-material-containing raw material including a carbon material that is a reducing material, and a caking raw material. A raw material supply means including a binder silo containing a binder, a rotary bed type reduction furnace for reducing the iron oxide with a hot gas, and a mixer for mixing a plurality of raw materials supplied from the raw material supply means. Forming means for forming the raw material mixed by the mixer, drying means for drying the raw material formed by the forming means, and the raw material dried by the drying means to the rotary bed reduction furnace In a reduction facility for reducing reduced iron, which produces reduced iron, comprising: a supplying means for supplying, and an exhaust duct for exhausting the hot gas from the rotary bed type reduction furnace, wherein the raw material supplying means has a basicity of Basicity adjustment for adjustment Reduction facility of the low reduction ratio reducing iron comprising the basicity adjustment silo for storing the material.

A reducer measuring device for measuring the amount of SiO _{2 and the} amount of CaO in the reducer raw material is provided between the reducer silo and the mixer, and the reducer silo and the mixer are provided between the reducer silo and the mixer. comprising a reducing agent metering device for metering the amount of SiO ₂ and CaO amount of carbonaceous material contained in the raw material, the binder meter for weighing the amount of SiO ₂ and CaO amount of the binder between the binder silo and the mixer The reduction equipment for reduced iron with a reduced reduction rate according to claim 1, wherein a basicity adjustment measuring device is provided between the basicity adjustment silo and the mixer.

Wherein the amount of SiO ₂ and CaO amount of the reductant in the material, and SiO ₂ amount and the amount of CaO of said Kaesumi material-containing raw material the reducing material meter is weighed, the binder in which the reducible substance measuring instrument for weighing The basicity-adjusting measuring device is configured to adjust the basicity of the raw material supplied to the mixer to 0.3 or more and 0.6 or less based on the amount of SiO _{2 and the} amount of CaO in the binder measured by the measuring device. The apparatus for reducing reduced-reduced iron according to claim 2, wherein the basicity adjusting raw material is supplied to the mixer.

A mixing raw material measuring device for measuring the amount of SiO ₂ and CaO in the mixed raw material between the mixing device and the molding means, wherein a basicity adjusting measuring device is provided between the basicity adjusting silo and the mixing device; The low-reduction-rate reduced iron reduction facility according to claim 1, further comprising:

The basicity adjustment is performed on the basis of the amount of SiO _{2 and the} amount of CaO in the mixed raw material measured by the mixed raw material meter so that the basicity of the raw material supplied to the mixer is 0.3 or more and 0.6 or less. The reduction equipment for reduced reduced-reduced iron according to claim 4, wherein a measuring device for supplying the basicity adjusting raw material is supplied to the mixer.

6. The reduction equipment for reduced reduced reduced iron according to claim 1, wherein the basicity adjusting raw material contains a Ca compound.

The method according to any one of claims 1 to 6, wherein the rotary bed reduction furnace includes a CO measuring device for measuring a carbon monoxide concentration, and a CO ₂ measuring device for measuring a carbon dioxide concentration. Low reduction rate reduction equipment for reduced iron.

The reduction of the reduced reduced-reduced iron according to claim 7, wherein the exhaust duct is provided with at least a CO measuring device for measuring a carbon monoxide concentration or an O ₂ measuring device for measuring a oxygen concentration. Facility.

The low-reduction-rate reduced iron reduction facility according to any one of claims 1 to 8, wherein the rotary bed type reduction furnace includes a plurality of fluid supply units that supply a fluid containing oxygen.

The low-reduction-rate reduced iron reduction facility according to claim 9, wherein the oxygen-containing fluid is oxygen-enriched oxygen-containing gas or air.

11. The reduction facility for low-reduced-rate reduced iron according to claim 9, further comprising a fluid control unit that adjusts a fluid supply amount of the fluid supply unit so that a CO ratio becomes 0.2 or less.

The rotary bed type reduction furnace includes a temperature measuring device for measuring a temperature in the furnace, and a plurality of hot gas burners for generating a hot gas in the furnace. The reduction equipment for reduced iron as described in [1].

13. The reduction equipment for reduced reduced-reduced iron according to claim 12, further comprising a hot gas burner adjusting means for adjusting the hot gas burner so that the temperature indicated by the temperature measuring device is 1300 ° C. or lower.

The low reduction rate according to any one of claims 1 to 13, further comprising rotating means capable of adjusting the rotation speed of the rotary bed type reduction furnace so that the reduction rate of iron oxide is 80% or less. Reduction equipment for reduced iron.

A material to be reduced to be an iron source of reduced iron, a carbon material-containing material containing a carbon material to be a reducing material, a binder to be a caking material, and a basicity adjusting material for adjusting the basicity, A bulk raw material for a rotary bed type reduction furnace, wherein the raw material is contained so as to have a basicity of 0.3 or more and 0.6 or less.

The bulk raw material for a rotary bed reduction furnace according to claim 15, wherein the basicity adjusting raw material contains a Ca compound.

A material to be reduced to be an iron source of reduced iron, a carbon material-containing material containing a carbon material to be a reducing material, a binder to be a caking material, and a basicity adjusting material for adjusting the basicity, A method for reducing reduced-reduced iron, comprising reducing a lump-containing raw material in a rotary bed-type reduction furnace.

18. The method for reducing reduced-reduced iron according to claim 17, wherein the raw material is reduced at a temperature of 1300 [deg.] C. or lower in a rotary bed type reduction furnace.

19. The method for reducing reduced-reduced iron according to claim 17, wherein the raw material supplied to the rotary bed type reduction furnace is subjected to a reduction treatment at a reduction rate of 80% or less.

The low reduction according to any one of claims 17 to 19, wherein a basicity in the bulk raw material supplied to the rotary bed type reduction furnace is added and blended so as to be 0.3 to 0.6. Rate reduction method of reduced iron.