JP3930570B2 - Method for producing sintered ore and sintering machine therefor - Google Patents

Method for producing sintered ore and sintering machine therefor Download PDF

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JP3930570B2
JP3930570B2 JP51056998A JP51056998A JP3930570B2 JP 3930570 B2 JP3930570 B2 JP 3930570B2 JP 51056998 A JP51056998 A JP 51056998A JP 51056998 A JP51056998 A JP 51056998A JP 3930570 B2 JP3930570 B2 JP 3930570B2
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務 岡田
陽三 細谷
正則 中野
謙一 樋口
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • C22B1/20—Sintering; Agglomerating in sintering machines with movable grates
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • C22B1/20—Sintering; Agglomerating in sintering machines with movable grates
    • C22B1/205—Sintering; Agglomerating in sintering machines with movable grates regulation of the sintering process

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Description

技術分野
本発明は高炉製造法の原料である焼結鉱を製造する方法及び焼結機に関し、特に焼結層のパレット上方から下方に向かって燃焼溶融帯を移行させる際に、所定の厚み方向の焼結層を得た後に、酸素含有ガスの供給量を増大して、差圧を増加させて前記燃焼溶融帯の移行速度を極端に加速し、生産率を増大するとともに成品の品質および歩留りを向上する焼結鉱の製造方法およびその焼結機に関する。
従来の技術
鉄鉱石の焼結に関しては、ドワイトロイド式焼結機が広く用いられている。これは、原料粉鉱石に石灰石や珪石等の溶剤と粉コークス等の燃料と水とを加えて混合、造粒した配合原料を、キャタピラ状に配列した焼結パレット上に充填して原料充填層を形成し、焼結パレットを順次水平移動して、点火炉内で充填層の表面に点火した後、下方から吸引して、配合原料内のコークス等の燃料を燃焼させ、発生した熱で原料粉鉱石を溶融、凝固し、燃焼帯を漸次表層部から下層部に移行させて焼結するもので、焼結時間は20〜40分程度である。
グリーナワルド式焼結機等のような他の回分式焼結機に比べて、ドワイトロイド式焼結機は連続式であり、大量生産に適しているのが広く用いられている理由である。現在のドワイトロイド式焼結機は大型化しており、幅５ｍ×長さ100ｍといったものまであるが、生産率は34〜43ｔ／ｄ／ｍ2程度である。
ここで、世界的な資源事情を鑑みると、高炉製造法の原料となる塊鉱石の供給量不足が顕著となっており、これに伴い塊鉱石の価格も増大する一方なので、粉鉱石の多量使用が求められている。ただし、焼結鉱の生産量を増大するために、焼結機を増設したり、あるいは焼結機を更に大型化すると多額の設備投資が必要になるばかりでなく、排出される排ガス量が増加し環境上も好ましくない等の問題が起こる。このため、焼結機の生産性向上が強く求められている。ただし、焼結鉱の製造は、高炉製造法から要求される成品焼結鉱の品質を維持して生産率を最大とすると共に、燃料原単位と点火燃料原単位は最小とし、NOx排出を極力抑制するような操業が求められる。従って、実際の操業では、焼結鉱の品質を維持する範囲内で、副原料として添加している珪石や蛇紋岩、石灰石、燃料として添加している粉コークスや無煙炭などの量、点火時の燃料であるコークス炉ガスや微粉炭などの量は少なくする方が良い。
ところが、いたずらに焼結原料への副原料や燃料の配合割合、点火燃料の量を下げても良い結果が得られるものではなく、それらを大幅に低下させると焼結鉱の冷間強度やRDI（還元粉化率）を悪化させたり、返鉱が多くなって、むしろ燃料原単位や点火燃料原単位の悪化を引き起こし、さらにNOx転換率が悪化してNOx排出量は逆に増加することになる。また、焼結鉱のSiO2を5.0mass％以下に低下させると、RDIが大きく悪化することもよく知られている。
特公昭55-19299号公報には、「ストランド上部の前半部に負圧の前半フード部を設け、ストランド上部の後半部に加圧の後半フード部を設けて、後半部の加圧力と前半部の負圧力により後半部の排ガスを循環すれば、排ガス量を減らすとともに、電力費の低減、生産性の低下を防止できる」ことが開示されている。しかし、この方法は後半部の大気で焼結させる部分を正圧用フードで被い、後半部のウインドボックスに続くブロアーを除去し、設備費を極力抑えた排ガス循環設備により排ガス量を低減させるのが目的であり、原料充填層内の燃焼溶融帯の移行速度を積極的に増大させ生産性の向上を図ることなどは何ら言及されていないものであった。さらに、開示された排ガス組成や、排ガス特性、図面などから、この方法における焼結完了点は後半フード部の初期であり、後半部の残りの範囲でストランド上でのクーリングを行っているとしか考えられない。従って、焼成完了点を極力排鉱部に近づけてストランド全体を使って生産率を最大とするものではない。
特公昭56-19556号公報には、「加圧焼結ゾーンを形成する正圧フードを設けるとともに、該正圧フードの給排鉱側端部に吸引により負圧ゾーンを形成する負圧フードを設ければ、設備全体を覆う気密ハウジングを要せずに加圧焼結法により生産性及び操業コストを改善できる」ことが開示されている。しかし、この方法は従来の加圧焼結法における問題点である、焼結パレットの移動経路上でのハウジング内への原料供給始端部及びハウジング内からの焼結鉱の搬出端部における加圧空気の大気中への流出を防止することが目的であり、原料充填層内の焼結帯の移行速度を積極的に増大させ生産性の向上を図ることなどは何ら言及されていないものであった。また、給鉱側端部に吸引による負圧ゾーンを形成するためには、この部位の吸引流速を従来の大気を吸引する方法の吸引流速よりも大きくしなければならない。このために、従来から問題であった原料層上層部の焼成における高温保持時間の不足を助長してしまい、原料層上層部の歩留り、品質を悪化させるので、トータルの生産性を大きく増大させるものではなかった。
特開昭61-243131号公報には、「加圧焼結法に必要な大型の気密ハウジングを不用とするために、無端状パレット上の焼結鉱の上面にフードを設け、フード内に空気を押し込み、無端状パレット下の風箱内を負圧にすればコストの低減を図ることができる」ことが開示されている。しかし、従来の排気ファンの電力に対して、押し込みと排気ファンを合わせたトータル電力の削減が目的であり、原料充填層内の燃焼帯の移行速度を増大させ生産性の向上を図ることなどは何ら言及されていないものであった。つまり、点火部から排鉱部までのストランド全体において、プロセスに必要な空気圧である原料充填層上部と下部の差圧を一定条件とするために押し込みファンと排気ファンをバランスさせて、現行の焼結機が体積膨張した高温空気を全量排気しているのに対し、室温空気を押し込み送風することでトータル電力の低減を図るものであって、生産性向上に必要な原料充填層内の燃焼帯の移行速度を積極的に増大させるものではない。
特公平５−55574号公報には、「パレット長手方向に複数の風箱を区分して、該区分された複数の風箱群単位に該パレット上に装入積層された焼結原料の焼結反応に対応して、吸引負圧を焼結反応の初期においては通常操業の吸引負圧に比較して減少し、焼成反応終了点に到る中期においては増加し、該焼成反応終了点付近からの終期においては減少するように制御すれば、焼結ベッド上層部の歩留り、落下強度（SI）、RDIが向上し、それに加えて排風電力を削減することと焼結鉱顕熱を効率的に回収することができる」ことが開示されている。しかし、焼結ベッド上層部の焼結鉱は、下層部の焼結鉱よりRDI及びSIはすでに改善されており、焼結鉱全体の品質をより改善するには、焼結ベッド中・下層部の焼結鉱を改善することの方が重要である。また、焼結ベッド上層部の歩留り改善と焼結鉱の品質改善、電力原単位低減が多少できても、焼成の初期と中期と後期の大気吸引する風量のバランスを改善し省エネルギーを図るものであり、中層部での歩留り低下、下層部でＳＩ低下が見られるなどの悪影響もあった。
また、焼結鉱の顕熱回収エネルギーを増大するためには、焼成終期の成品焼結鉱の温度を増大させる必要があり、原料充填層内の赤熱帯（燃焼溶融帯）の高さ方向の幅を増大させなければならない。このため、該赤熱帯の通気抵抗は非常に大きくなり、生産率を大きく支配する赤熱帯の移行速度を増すことが出来ず、焼成終期の生産率を逆に悪化させるなどの悪影響を及ぼし、トータルとしての生産率の大幅な向上は期待できないものであった。
さらに、焼成反応の中期において生産率を確保するために吸引負圧を増加するとあるが、開示されている説明図によると、排ガス風量は中期において焼成前期に近いところは、負圧を従来法より増しているにも関わらす小さくなっているなど、トータルの生産率を大きく増大させるものではないと考えられる。
発明の開示
前記従来の技術は、いずれも設備面の経済性、操業コストを改善しようとするものである。従って、いずれも配合原料を焼結パレット上に層厚400〜600mm程度に充填し、点火炉にて配合原料中の燃料に着火する現状の操業条件を前提にしている。
焼結機の生産率は、原料充填層内の燃焼溶融帯が表層部から漸次下層部に移行するときの移行速度に大きく依存する。焼結の生産率を向上する上で問題となるのは、焼結機は点火部から排鉱部までのストランド内で原料充填層の上層から下層までを焼成する過程において、燃焼溶融帯の移行速度が遅いということである。従って、燃焼溶融帯の移行速度が従来と同じであれば、充填層の層厚や焼結パレットの移動速度を増加させると、焼結完了に必要な焼結機の長さ及び焼結時間が増加するので、生産率は向上しない。
また、燃焼溶融帯の移行速度を大きくし過ぎると、コークスの燃焼不足を引き起すことなどから焼成に必要な熱量を確保できないので、歩留りや品質の悪化を招く原因になる。従って、焼成反応に必要な熱量を確保するとともに、燃焼溶融帯の移行速度を大きくすることが、焼結機の生産率を大幅に向上させるために重要である。さらに、原料充填層の中では、燃焼溶融帯の通気抵抗が大きいので、燃焼溶融帯の原料充填層高さ方向の厚みを必要最小限にすれば、通気性を向上しコークス燃焼速度を上げて燃焼溶融帯の移行速度を増大させることができる。このように燃焼溶融帯の上にある冷却帯の冷却速度と燃焼溶融帯の移行速度をバランス良く制御することも、焼結機の生産率を大幅に向上させるために重要である。
一般的に、燃焼溶融帯の移行速度を増加させるためには、ブロアーの負圧を増大して吸引流速を増加させ、原料充填層への酸素の供給量を増加させることが考えられる。
しかし、原料充填層上層部の歩留り、焼結鉱の品質低下を防止するには原料充填層上層部の高温保持時間を保つ必要があり、原料充填層上層部の焼成エリア、すなわち焼結ストランドの前段での燃焼溶融帯の移行速度は現状より増加できない。また、ブロアーの負圧の増大により、重力と送風圧力が重畳して原料充填層が圧縮されて通気が阻害されること、さらに排風量及び漏風量の増大を招く問題などがあり、ブロアーの負圧を大きく増大させることは行われていない。
一方、高炉の高微粉炭比操業時のスラグ量低減のために、低SiO2焼結鉱の製造が求められているが、このときに顕在化する生産率やRDIの悪化、NOx排出量の増加などの問題が解決されないでいた。
そこで本発明は、原料充填層の層厚や焼結パレットの移動速度を増加させて焼結機の生産性を大幅に向上できる焼結鉱の製造方法、低SiO2焼結鉱の製造方法、及びこれらに使用する焼結機を提供することを目的とする。
上記の目的を達成する本発明の要旨は、下記の通りである。
（１）原料粉鉱石と溶剤と燃料とを含む配合原料を焼結機のパレット上に装入して原料充填層を形成した後、原料充填層に点火して上方から下方に焼結反応させることによって焼結鉱を製造する方法において、前記焼結パレット上の原料充填層の上に酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧するとともに、原料充填層の下方から大気圧に対して−2000〜−１mmAqで吸引するとともに、原料充填層上層部を十分に焼成した時点で、原料充填層に供給する酸素含有ガスの質量流量を、該原料充填層上層部を焼成する範囲において供給する酸素含有ガスの質量流量の1.01〜2.6倍に変更して焼結することを特徴とする成品歩留りおよび品質の優れた成品を得る焼結鉱製造方法。
（２）原料粉鉱石と溶剤と燃料とを含む配合原料を焼結機のパレット上に装入して原料充填層を形成した後、原料充填層表層に点火して上方から下方に燃焼溶融帯を移行させながら連続的に焼結鉱を製造する方法において、前記焼結パレット上の原料充填層の上に酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧するとともに、原料充填層の下方から大気圧に対して−2000〜−１mmAqで吸引するとともに、燃焼溶融帯の形成範囲の先端が原料充填層の表層から原料充填層高さの２０％の位置より下方に達した時点で、原料充填層に供給する酸素含有ガスの質量流量を、該原料充填層を焼成する範囲において供給する酸素含有ガスの質量流量の1.01〜2.6倍に変更して焼結することを特徴とする成品歩留りおよび品質の優れた成品を得る焼結鉱製造方法。
（３）前記焼結パレット上の原料充填層の上で、パレット幅方向の５〜95％の範囲内に酸素含有ガスを加圧供給する加圧フードを設け、該加庄フード内を大気圧に対して100〜3000mmAqに加圧することを特徴とする（１）または（２）のいずれかに記載の焼結鉱製造方法。
（４）前記原料充填層の上方から下方のうち、燃焼溶融帯の形成範囲の先端が原料充填層の表層から原料充填層高さの２０％の位置より下方に達した以降の範囲の原料充填層の上に、酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧することを特徴とする（１）から（３）のいずれかに記載の焼結鉱製造方法。
（５）前記原料充填層の上に設けた酸素含有ガスを加圧供給する加圧フードに焼結排ガスを循環させることを特徴とする（１）から（４）のいずれかに記載の焼結鉱製造方法。
（６）前記焼結パレットのグレート上にパレット進行方向にほぼ平行に板状のシンターケーキ支持スタンドを複数枚設けたドワイトロイド式焼結機を用いて焼結することを特徴とする（１）から（５）のいずれかに記載の焼結鉱製造方法。
（７）化学成分として3.9〜4.9mass％のSiO2を含む焼結鉱を製造することを特徴とする（１）から（６）のいずれかに記載の焼結鉱製造方法。
（８）前記原料充填層の層厚を600〜1500mmとすることを特徴とする（１）から（７）のいずれかに記載の焼結鉱製造方法。
（９）焼結ストランド下部の複数のウインドボックスを吸引ダクトに並列に接続し、該吸引ダクトにメインブロアーを設けた下方吸引式の焼結機において、焼結パレットの原料充填層の上に酸素含有ガスを加圧供給する加圧フードを設けるとともに、点火部から排鉱部までの吸引ダクト長さの30％から焼結完了点の範囲内のダクトから吸引し、かつ該吸引ダクトに排出するブロアーをさらに設けたことを特徴とする焼結機。
（１０）前記焼結ストランド下部の複数のウインドボックスを並列に接続した吸引ダクトを、点火部から排鉱部までのストランド長さ30％から焼結完了点の範囲内と残りの範囲に分割し、各々独立してブロアーを設けたことを特徴とする（９）に記載の焼結機。
（１１）前記原料充填層の上方から下方のうち、燃焼溶融帯の形成範囲の先端が原料充填層の表層から原料充填層高さの２０％の位置より下方に達した以降の範囲の原料充填層の上に、酸素含有ガスを加圧供給する加圧フードを設けたことを特徴とする（９）または（10）に記載の焼結機。
（１２）前記焼結パレット上の原料充填層の上で、パレット幅方向の５〜95％の範囲内に酸素含有ガスを加圧供給する加圧フードを設けたことを特徴とする（９）から（11）のいずれかに記載の焼結機。
（１３）前記原料充填層の上に設けた酸素含有ガスを加圧供給する加圧フードに焼結排ガスを循環させることを特徴とする（９）から（12）のいずれかに記載の焼結機。
（１４）前記酸素含有ガスを加圧供給するフードの下端部にシール機構を設けたことを特徴とする（９）から（13）のいずれかに記載の焼結機。
（１５）下方吸引式焼結機の構造が、焼結パレットのグレート上のパレット進行方向にほぼ平行に板状のシンターケーキ支持スタンドを複数枚設けたことを特徴とする（９）から（14）のいずれかに記載の焼結機。
【図面の簡単な説明】
第１図は本発明の前提となる焼結機の実施態様を示す図である。
第２図は本発明の前提となる別の焼結機の実施態様を示す図である。
第３図は本発明の実施例１ｂ〜１ｅに係る焼結機の実施態様を示す図である。
第４図は本発明の実施例２ａ〜２ｄ、３ｃに係る焼結機の実施態様を示す図である。
第５図は本発明の焼結機の他の実施態様を示す図である。
第６図は本発明に係る焼結機の加圧フードのシール機構を示す図である。
第７図は本発明に係る焼結機の板状のシンターケーキ支持スタンドを示す図である。
第８（ａ）図は、本発明に係るパレットにおける燃焼溶融帯の推移を示す説明図である。第８（ｂ）図は、本発明に係るパレットにおける燃焼溶融帯の、Ａ−Ａ’断面図である。第８（ｃ）図は、本発明に係るストランド上でのクーリング時の燃焼溶融帯の推移を示す説明図である。
発明を実施するための最良の形態
一般に焼結鉱は、原料粉鉱石と溶剤と燃料とを含む配合原料をドワイトロイド式焼結機のパレット上に装入して原料充填層を形成し、点火部で点火した後、酸素含有ガスを下方から吸引しながら排鉱部へと移動させ製造している。従って、焼成は原料充填層の上方から下方へと行われるが、ストランド長さ方向と対比して表現でき、かつ理解し易いため、以下ではストランド長さを用いて本発明を説明する。
第８（ａ）図は、本発明の原料充填層焼結過程の一例を示す説明図である。この図で、Ｉは初期原料帯、IIは湿潤（水分凝縮）帯、IIIは乾燥帯、IVは燃焼帯、Ｖは溶融帯およびVIは焼結帯である。第８（ｂ）図は、第８（ａ）図の中央部分でのＡ−Ａ’断面図である。また、点Ｂは、本発明における初期に燃焼溶融帯を形成し、原料充填層での酸素含有ガスの供給量を変更し増大させる最も点火炉に近い位置を示し、また点Ｃは燃焼完了点を示す。通常の操業では、ストランド全体を効率良く使って安定的に生産するために、焼結完了点が一定となるように操業する。生産量を重視する場合は、焼結完了点を極力排鉱側に近づける操業とし、また、歩留りや品質を重視する場合には、ウインドボックスの一つあるいは二つ分の余裕をもって焼結完了点を点火炉側に近付づけて一定となるように操業する。ただし、ストランド上でクーリングを行う場合には、例えば第８（ｃ）図に示すように、焼結完了点Ｃ’をストランドの中間部にまで変更した操業が行われる。この場合には、以下に開示する本発明をもとに層厚、またはストランド長さ方向の位置でもって酸素含有ガスの供給量の変更をすれば良い。さらに、以下の説明において焼結完了点は、点火部からストランド長さ９５％の位置となる例を示した。なお、送風あるいは吸引圧力は大気圧に対する圧力で示している。
点火部からストランド長さ30％以下の範囲は原料充填層の上層部２０％の焼成エリアにほぼ相当し、原料充填層上層部の歩留りや品質は一般に中下層部に比べて劣っている。これは焼成反応に必要な熱量を与えるコークス燃焼速度等が、点火直後であるため不十分となっているからである。さらに、表面からの放散熱があること等の原因による。従って、焼結反応に必要な熱量を確保する必要があるために、原料充填層の上層部の焼成過程で燃焼溶融帯の移行速度を増加させることは、歩留りや品質悪化などの理由から好ましくない。
従って、本発明では原料充填層の上層部の焼成エリアである点火部からストランド長さ30％以下の範囲は、従来と同じ吸引負圧にすれば、原料充填層の上層部の高温保持時間を確保することができるので、原料充填層の上層部の歩留りや品質を確保することができる。
原料充填層の上部の歩留りや品質を積極的に向上させるには、該部位の焼成熱量を増大させれば良い。このためには、該部位の吸引負圧を低くしたり、原料充填層上部のコークス偏析を強化したり、あるいは表層部にブリーズを添加すること等が好ましい。また、原料充填層の外部から熱量を加えることもでき、例えば、熱風を該部位に吸引させたり、マイクロ波等による誘導加熱を行うことができる。
点火部からのストランド長さ30〜95％の範囲は、原料充填層の中・下層部の焼成エリアにあたり、原料充填層の上層部の焼結帯は通気抵抗が小さいのに対し、原料充填層の中層から下層部は通気抵抗の大きい燃焼溶融帯の厚みが大きくなるため通気抵抗が大きくなる。特に、ストランド長さ50〜95％では、通気性が悪化するとともに、焼成熱量も過剰になっている。この中層から下層部（点火部からストランド長さ30〜95％内の範囲）の範囲内の圧損の大きい燃焼溶融帯へ上方から強制的に供給して、酸素含有ガスの質量流量を前記範囲を除くストランド範囲の原料充填層に供給する酸素含有ガスの1.01〜2.6倍に増加させれば、中層から下層部のコークス燃焼速度を増加させて燃焼溶融帯の移行速度を増加させ、かつ燃焼溶融帯上の冷却帯の冷却速度も増加させ、焼成に必要な熱量を確保すると共に、燃焼溶融帯の厚みが減少して、通気性が向上する。このように、燃焼溶融帯の温度、及び原料充填層高さ方向の厚みに依存する焼成熱量と通気性の制御が焼結の生産率を向上する上で重要である。
本発明で質量流量とは、単位時間当たりに流れるガスの質量を表すものであり、その単位はkg／ｓなどで表現される。また、一般に使用されている流量とは体積流量を示し、単位時間当たりに流れるガスの体積を表すものであり、その単位はｍ3／ｓなどで表現される。質量流量が同じであれば、体積流量は気体の状態方程式に従い温度や圧力によって変化する。
また、本発明における酸素含有ガスとは、大気はもちろんのこと、焼結機から排出される排ガスや、他のプロセスからの排ガスなども含むと共に、大気と排ガスの混合ガス、酸素富化したガスも含むもので、酸素濃度が12〜40vol％のガスが好ましい。
ここで、点火部からのストランド長さ30〜95％の範囲内の原料充填層に供給する酸素含有ガスの質量流量を、前記範囲を除くストランドの範囲の原料充填層に供給する酸素含有ガスの質量流量に対して1.01〜2.6倍に調節するのは、質量流量が1.01倍未満では燃焼溶融帯の移行速度がほとんど変化せず、2.6倍超ではガス流速が増加しすぎて燃焼溶融帯が過冷却され、または原料充填層上下の差圧の増加により原料充填層が圧密され通気性が阻害されるためである。さらに、点火部からのストランド長さ50〜85％の範囲内の原料充填層に吸引する酸素含有ガスの質量流量を、前記範囲を除くストランドの範囲の原料充填層に供給する酸素含有ガスの質量流量に対して1.1〜1.8倍に調節することが、焼結鉱の生産性向上の点で特に好ましい。
また、酸素含有ガスとして大気を吸引して燃焼溶融帯の移行速度を増加させる場合には、上記規定の質量流量とするため、点火部からストランド長さ30〜95％の範囲内における原料充填層の層厚方向の差圧を前記範囲を除くストランド範囲の原料充填層の層厚方向の差圧に対して1.1〜5.0倍とすることが好ましい。ここでストランド長さ30〜95％の範囲内は、それ以外の範囲に比較して通気抵抗が1.5〜５倍程度大きい。したがって、前記差圧が1.1倍未満では通風量増加による燃焼溶融帯の移行速度の促進の効果が少なく、差圧が5.0倍を越えるとガス流速が大きくなりすぎて、冷却速度が大きく増すために高温保持時間が確保できなくなり、原料充填層が圧密化して通気性が悪化するため好ましくない。さらに差圧を1.2〜2.0倍とすることが生産性向上の点で特に好ましい。なお、ガスの供給量は点火部側から排鉱部側へ除々に増加させ、燃焼溶融帯の移行速度と冷却速度を近づけるのが好ましい。急激に供給量を増加させると、短時間ではあるが、コークス燃焼速度よりも冷却速度の方が大きくなり、十分な焼成熱量が保てなくなる部位が発生し、該部位の歩留り、焼結鉱の品質の悪化を招いてしまうからである。
以上のように、点火部からのストランド長さ30〜95％の範囲内の原料充填層の差圧を増加して質量流量を増加させれば焼結鉱の生産率を大幅に向上するとともに、歩留りおよび品質の優れた成品を得ることができる。差圧を増しガスの供給量を増加すると、これに連れられて該部位の排ガス排出量も増大するが、焼成反応が活発で酸素消費効率が高い部位なので、酸素消費効率を低下させることなく、さらに上層部分及び排鉱部近傍の過剰なガスの供給量を極力抑えることなどから、風量原単位を削減できる。
本発明者等は、原料充填層の下方吸引と上方からの加圧を組み合わせて酸素含有ガスの質量流量を増加させれば原料充填層の圧密化に起因する通気性悪化を回避して、点火部からストランド長さ30〜95％の範囲内における原料充填層に供給する酸素含有ガスの質量流量を、前記範囲を除くストランドの範囲の原料充填層に供給する酸素含有ガスの質量流量に対して1.01〜2.6倍にし、さらに好ましくは原料充填層の層厚方向の差圧を前記範囲を除くストランド範囲の原料充填層の層厚方向の差圧に対して1.1〜5.0倍に調節すれば、燃焼溶融帯の移行速度を増大できるとともに、成品歩留りおよび品質を向上できることを見出した。
焼結パレット上に装入した原料充填層の上を覆う加圧フードを設け、フード内を加圧して、上方から原料充填層に酸素含有ガスを加圧送風するとともに、パレット直下にあるウインドボックスから吸引排気し、原料充填層上方と原料充填層下方との間の差圧を制御して、原料充填層の上方から下方にガスを流す。このようにして、従来は原料充填層の上が大気圧で下方から吸引して形成している原料充填層内の静圧に対して、本発明では原料充填層内の静圧を増加できる。従来の大気を吸引する方法と原料充填層上下の差圧が同じであれば、本発明では原料充填層内に供給する質量流量を従来よりも増加させることができ、原料充填層内のガス密度を従来よりも大きくできる。その結果、原料充填層内への酸素含有ガスの供給量が増加して、原料充填層中のコークス燃焼速度が大きくなり、燃焼溶融帯の焼成熱量を増大するとともに、移行速度を増加させ、冷却帯の移行速度も促進できる。原料充填層内の静圧が増せば気体−固体間の伝熱速度も増加し、燃焼溶融帯の移行及び冷却帯の冷却を促進できる。
また、上方からの押し込み送風では、通気抵抗の小さい焼結帯を通し、均一なガス流れを形成して反応の起きている燃焼溶融帯へガスを供給することができる。一方、下方からの吸引によるガスの供給では、通気抵抗の比較的大きい湿潤帯、及び焼成反応の起きている燃焼溶融帯の大きい通気抵抗を受けるので、ガスが通気抵抗の小さいところを優先的に流れるため、不均一なガス流れを形成し、気体−固体間の反応効率が悪化し易い状態である。従って、上方から押し込むガス流れの方が下方からの吸引によるガス流れに対して均一なガス流れを形成するので、酸素消費効率が向上し、焼結鉱製造に必要な風量原単位を低減できる。
さらに、ストランド長さ30〜95％の範囲内の原料充填層の差圧を増せば、差圧増大による質量流量の増加による効果と、静圧レベル増大による効果が加わり、その生産性向上効果は非常に大きくなるのである。
原料充填層内の質量流量及び静圧レベルを従来方法より増加させるためには、原料充填層上方に設けた加圧フード内を100〜3000mmAqの範囲で加圧し、原料充填層の下方から−2000〜−１mmAqでガスを供給する。原料充填層上方の圧力が100mmAq未満であれば、従来の操業に比べてあまり生産性に変化がなく、原料充填層上方の圧力が3000mmAq超となると、原料充填層上下の差圧が大きくなりすぎて、重力と送風圧力が重畳して原料充填層を圧縮する力が大きくなり、原料充填層が圧密化して通気性が悪化するため好ましくない。さらに、加圧力を大きくするほど、フードとフードと接する対象物との間からの漏風が増し、シールが困難になることや、大がかりな設備を必要とするなどの問題が起きる。パレット直下にあるウインドボックスの吸引負圧は、原料充填層の上下の差圧パターンの設定などによるが、−2000〜−１mmAqの範囲にする。−2000mmAq未満であれば、原料充填層上方を加圧しても、原料充填層内の静圧レベルが従来法よりあまり大きくならないので、酸素供給速度増によるコークス燃焼速度の増加やガス密度増による伝熱速度の増加は少ない。−１mmAq超であれば、排ガスを吸引することができないからである。
点火部からストランド長さ30〜95％の範囲内の原料充填層の上下の差圧は、層厚やパレット速度に依存するが、1000〜3000mmAqにするのが好ましい。原料充填層上下の差圧が1000mmAq未満では、原料充填層内の差圧が従来法よりも小さく、静圧を増すことによる効果よりも、ガス流速が低下することによる悪影響が大きくなるからである。原料充填層内の差圧を3000mmAq超にすることは、重力と送風圧力が重畳して原料充填層を圧縮するので、原料充填層が圧密化して通気性が悪化するため好ましくない。
点火部から排鉱部までの全範囲にストランド長さ方向に複数に分割して加圧フードを設けることにより、点火部からストランド長さ30〜95％の範囲内における原料充填層に吸引する酸素含有ガスの質量流量を、前記範囲を除くストランドの範囲の原料充填層に供給する酸素含有ガスの質量流量に対して1.01〜2.6倍に、さらに原料充填層の層厚方向の差圧を前記範囲を除くストランド範囲の原料充填層の層厚方向の差圧に対して1.1〜5.0倍に容易に調節できる。
前述したように、点火部からのストランド長さ30％の範囲は、原料層上層部の歩留り、焼結鉱の品質低下を防止するために高温保持時間を保つ必要があり、上層部の焼成においては燃焼帯の移行速度を現状より増加できない。従来の400〜600mmの層厚の場合、点火部からのストランド長さ30％以下の範囲は原料充填層上方から100〜1000mmAqで加圧送風し、パレット直下にあるウインドボックスから吸引排気する吸引負圧は−1000〜−１mmAqにし、原料充填層の上下の差圧を300〜2000mmAqに調節して、従来の下方吸引の差圧と同じ差圧または小さい差圧とすれば、高温保持時間を確保または増加し、焼成に必要な熱量を得ることができる。このとき、原料充填層上層の酸素供給速度が増加するため、酸素富化と同じようなコークス燃焼性の向上効果も得ることができ、原料充填層上層の歩留及び品質の向上をさらに図ることができる。
ただし、ストランド長さ30〜95％の範囲内の原料充填層以外は通常の下方吸引で生産率を大きくする効果が比較的小さいため、加圧フードを点火部からストランド長さ30〜95％の範囲内に設けることが設備の簡素化の点で好ましい。さらに、加圧フードをストランド長さ方向に複数に分割して設ければ、点火部側から排鉱部側へ質量流量を段階的に変化させることもできる。
さらに、原料充填層のパレット側壁からパレット幅方向に５％以内の側壁近傍は中心部に比較して通気抵抗が大きくないため、燃焼溶融帯の移行速度が大きい。このため、原料充填層の幅方向の５〜95％の範囲内に加圧フードを設け、燃焼溶融帯の移行速度が幅方向に均一になるようにガスを供給すれば、燃焼溶融帯の移行速度を増加する効果がさらに大きくなる。
加圧フードは移動する焼結パレットの上方に設置するが、漏風を避けるため加圧フードの下端にシール機構を設けることが好ましい。シール機構としては、第６図に例示するように、加圧フード19の内圧によりフード下端部に設けたシート24を原料充填層７の上面に押しつけることによりシールし、パレットの移動と共に原料充填層７上を摺動させる構造が好ましい。また、数段のシール機構23を設けた構造、加圧フード19と原料充填層７との間に加圧フード19の外側からエアーブローする構造、パレット６の側壁部などを利用してシール機構を設けることなどもでき、これらの例に限られたものではない。
点火部からのストランド長さ30〜95％の範囲内、特に好ましくはストランド長さ60〜80％までの範囲の加圧フード内に、酸素濃度を12〜21vol％未満に調整したガスを供給して焼成するとRDIの向上に良いマグネタイトの生成が促進され、コークス中窒素のNOxへの酸化も抑制することができ、RDI改善とNOx発生の抑制に有効である。加圧フード内の酸素濃度を12〜21vol％未満に調整するには、焼結機の排ガスの一部を循環利用できる。この場合、原料充填層上方からガスを供給した風量を排ガス処理設備に送れるように吸引負圧と風量、設備の大きさなどを加味して排ガス循環用のブロアーの能力を設計する。
酸素濃度が21vol％未満では、マグネタイトの生成が促進されることによりRDIが改善され、酸素濃度が低いことによりコークス中窒素のNOxへの酸化が抑制されるが、12vol％未満になると生産性低下の悪影響が顕著になるため、酸素濃度は12vol％以上21vol％未満が好ましい。特に、酸素濃度を18vol％未満にすると、RDI改善とNOx発生の抑制の効果はより顕著になる。
特開平４−168234号公報に記載されている、パレット進行方向と平行に幅方向に板状のシンターケーキ支持スタンドを複数枚設置した焼結機を用いて焼成中にシンターケーキを支持することにより、原料充填層の下層部にシンターケーキの荷重が加わらなくなり、原料充填層の下層部の通気性を改善して、生産率が大きく向上する。さらに、シンターケーキの荷重が軽減されただけ、原料充填層上下の差圧を増すことができ、生産率をさらに向上できる。シンターケーキ支持スタンドの一例を第７図に示す。板状のシンターケーキ支持スタンド21の最適設置枚数はパレット６の大きさによるが、例えば幅４ｍ、長さ２ｍのパレットで、原料充填層厚500〜600mmの焼結機では、２〜10枚であり、高さは200〜400mmとするのが好ましい。シンターケーキ支持スタンドの枚数が多いほどシンターケーキに対して十分な支持効果が発揮できる。しかし、10枚を超えるとシンターケーキ支持スタンドの占める体積が増え、逆に生産率に対する悪影響が顕在化し始め、生産率の低下が見られるようになる。シンターケーキ支持スタンドでシンターケーキを支持すると通気性がさらに向上し、コークス燃焼速度が大きくなるためにCO発生量が増加し、その結果生成したNOをCOガスで還元する反応が活発になるために、NOxの発生も抑制される。このように、本発明においてシンターケーキ支持スタンドを複数枚設置することにより、両立が困難であったNOx発生抑制と、生産率向上、成品歩留向上、焼結鉱品質向上とを同時に実現できる。
本発明がSiO2を3.9〜4.9mass％含む低SiO2焼結鉱の製造に特に有効であるのは、SiO2が4.9mass％以下になると石灰石配合比が下がることやCaOとSiO2のスラグ主成分の減少の影響で生産率やRDIの悪化が顕著になり始め、3.9mass％未満になると本発明によっても生産率やRDIの悪化を改善できないからである。
本発明により、点火部から排鉱部までのストランドのうち、点火部からのストランド長さ30〜95％の範囲内の原料充填層に吸引する酸素含有ガスの質量流量を、前記範囲を除くストランドの範囲の原料充填層に吸引する酸素含有ガスの質量流量に対して2.6倍まで増加させることができるため、従来の400〜600mmの層厚での焼結操業では焼結パレットの移動速度を従来の2.0倍以上に増加させることができる。さらに、原料充填層の層厚を600〜1500mmと従来の２倍以上とすることさえ可能で、これにより焼結機の生産率を従来の焼結生産率に対して最大2.0倍にまで向上することが可能で、絶大な生産率向上効果を発揮するとともに、成品歩留りおよび品質の向上、排ガス風量原単位の削減効果を発揮する。また、生産率を一定に保ち、成品歩留りや焼結鉱品質の向上、排ガス風量原単位の削減を図ることもできる。
また、原料充填層下方から吸引する吸引負圧を小さくするほど、パレットとウインドボックスとの間の摺動部からの外気の流入を減少させることができる。従って、焼成に有効な風量が増加し漏風が低減するので、さらに生産性も向上し風量原単位も低減できる。
本発明の焼結鉱製造方法に用いる焼結機としては、焼結ストランド下部の複数のウインドボックスを吸引ダクトに並列に接続し、該吸引ダクトにメインブロアーを設けた従来の構造にさらにブロアーを加え、点火部から排鉱部までの吸引ダクト長の30〜95％の範囲内の任意の箇所から吸引し、かつ該吸引ダクトに排出することにより、点火部からストランド長さ30〜95％の範囲内における原料充填層に供給する酸素含有ガスの質量流量を、前記範囲を除くストランドの範囲の原料充填層に吸引する酸素含有ガスの質量流量に対して1.01〜2.6倍にし、さらに原料充填層の層厚方向の差圧を前記範囲を除くストランド範囲の原料充填層の層厚方向の差圧に対して1.1〜5.0倍に調節することができる。
さらに、前記吸引ダクトを点火部からストランド長さ30〜95％の範囲内と残りの範囲に分割し、各々独立してブロアーを設置した構造が質量流量、差圧の調節の点で好ましい。ブロアーはストランドの前段、中段、後段用と３機設けても良いが、前段と後段は差圧を変える必要がないため前段と後段を連結し、ストランド長さ30〜95％の範囲内の中段用とそれ以外の範囲用の２機とすることが好ましい。
上方からの加圧を組み合わせる場合には、加圧する原料充填層の上にフードを設け、フード内を加圧してフード内の圧力と下方にあるウインドボックス内の圧力を計測するのが好ましい。さらに、フードと原料充填層との間、および／またはフードとパレットとの間でシール構造を設けることが望ましい。
実施例
本発明を実施例１，２，３により詳細に説明する。
焼結面積500ｍ2で焼結パレット幅５ｍの実機焼結機をそれぞれ一部改造して、１水準７日間ずつの操業を行った。
実施例１
第３図は本発明の焼結機の実施例を示す図である。焼結配合原料１はサージホッパー２からドラムフィーダー３、原料装入装置５を介してパレット６上に連続的に供給され、パレット６上に原料充填層７として層状に積層される。この間、原料給鉱側のスプロケット４を回転させてパレット６を所定の速度で移動させると共に、パレット６の下側に複数個設けたウインドボックス８、メインダクト９、排ガス集塵機10を経てブロアー11により吸気し、煙突12より排ガスを排出する。さらに、メインダクト９の一部にはサブダクト13が連設されており、排ガス集塵機14を経てブロアー15により吸気し、排ガスをメインダクト９に戻す。ブロアー15により吸気した排ガスは、煙突12より排出することもできる。また、メインダクト９には、ダクト内の負圧を調節するダンパー16などを設けることが望ましい。
点火炉27により原料充填層７の上面に点火して、パレット６上の原料充填層７が排鉱部に達する間に全層にわたって焼結反応を完了させるように速度制御された連続運転が実施される。煙突12の前からブロアー18により、排ガスを加圧フード19に循環でき、同時に空気を混合することができる。この加圧フード19内を加圧する場合には、第６図に示すようなシール機構23を原料充填層表層部とフードの下端部との間に設けることによりフード内圧を保つ。パレット進行方向の長さ、及びパレット幅方向の長さを自由に設定できる。さらに、この装置では、原料充填層７の層厚を600〜1500mmと従来より厚く充填することもできるようになっている。
配合原料は、低SiO2焼結鉱の製造を特に目的とせずに、従来の一般的な配合として、種々の鉄鉱石及び石灰石、生石灰、蛇紋岩、スケール等の雑原料、返鉱、粉コークスを焼結鉱中のSiO2が5.8mass％，Al2O3が1.8mass％になるように調整し、塩基度は1.7になるように配合した。返鉱配合率は新原料の合計100に対して15％一定、コークス配合率は新原料の合計100に対して4.2％一定とした。比較例、実施例ともに同じ配合とした。
配合原料に返鉱、粉コークスを配合した後に水を添加してミキサーで混合、造粒して焼結機に装入した。操業は、焼結完了点が排鉱部の直前になるようにパレットスピードを調整した。
実施例１ｂでは、層厚を550mm、点火部から排鉱部までを−1000mmAqで下方吸引し、ストランド長さ30〜95％の間の原料充填層上部の加圧フード内を1500mmAqに加圧した。この場合、ストランド長さ50〜95％の範囲内ではそれ以外の範囲に対して、質量流量比は1.27で、層厚方向の差圧は2500mmAqであった。
実施例１ｃでは、層厚を550mm、点火部からストランド長さ30％、及びストランド長さ95％から排鉱部までを−500mmAqで下方吸引するとともに、該範囲にも加圧フードをさらに続けて加圧フード内の圧力を500mmAqとして加圧し、ストランド長さ30〜95％の間を−1000mmAqで下方吸引するとともに加圧フード内の圧力を2000mmAqに加圧した。この場合、ストランド長さ30〜95％の範囲内ではそれ以外の範囲に対して、質量流量比は1.77で、層厚方向の差圧は3000mmAqであった。
実施例１ｄでは、層厚を550mm、点火部から排鉱部までを−1000mmAqで下方吸引し、ストランド長さ50〜90％のパレット幅方向10〜90％の範囲に設けた加圧フード内に煙突前の排ガスを循環して、酸素濃度を18vol％に調節し、1500mmAqに加圧した。この場合、ストランド長さ50〜90％の範囲内ではそれ以外の範囲に対して、質量流量比は1.27で、層厚方向の差圧は2500mmAqであった。
実施例１ｅでは、層厚を550mm、パレットに板状のシンターケーキ支持スタントをパレット幅方向に均等に４枚平行に設置し、点火部から排鉱部までを−1000mmAqで下方吸引し、ストランド長さ50〜90％のパレット幅方向10〜90％の範囲に設けた加圧フード内を1500mmAqに加圧した。この場合、ストランド長さ50〜90％の範囲内ではそれ以外の範囲に対して、質量流量比は1.27で、層厚方向の差圧は2500mmAqであった。
実施例１ｆでは、層厚を800mm、これ以外の設定は実施例１ｅと同じにした。この場合、ストランド長さ50〜90％の範囲内ではそれ以外の範囲に対して、質量流量比は1.27で、層厚方向の差圧は2500mmAqであった。
比較例は、実施例と同じ配合原料を層厚550mm、負圧1500mmAq一定で点火部から排鉱部まで大気を吸引して、配合原料層内は負圧で焼結する従来法で焼結した。
第１表に比較例１と実施例１ｂ〜１ｆで得られた焼結鉱の生産率、成品歩留り、RDI、NOx排出量原単位を示す。ここで、NOx排出量原単位とは、排ガス風量と排ガス中NOx濃度との積で表される。第１表から分かるように、実施例１ｂ〜１ｆでは比較例に対して生産率が著しく向上した。また、従来は生産率が向上すると成品歩留りが低下する傾向があったが、本発明では成品歩留りも向上した。さらに、RDI、JIS-RI(JIS規格による最終還元率）とNOx排出量原単位も改善され、操業面及び環境面において優れた効果を発揮できた。

Figure 0003930570
実施例２
第４図および第５図は本発明の焼結機の他の実施例を示す図で、第３図に示した実施例との相違点は、メインダクト９を完全に分割して、独立したブロアー11，15を設けている点である。さらに、ブロアー29を設けることもできる。ストランド長さ方向に圧力パターンを複数設定する場合は、このようにブロアーを複数設ければ良い。
配合原料は実施例１と同じであり、操業は、焼結完了点が排鉱部になるようにパレットスピードを調整した。
実施例２ａでは、層厚を550mm、点火部からストランド長さ50％までを−1000mmAqとし、点火部からストランド長さ80％から排鉱部までを−1500mmAqで下方吸引して原料充填層上方は大気開放とし、ストランド長さ50〜80％の間を−500mmAqで下方吸引するとともに加圧フード内の圧力を2000mmAqとして加圧した。この場合、ストランド長さ50〜80％の範囲内ではそれ以外の範囲に対して、質量流量比は1.52で、層厚方向の差圧は2500mmAqであった。
実施例２ｂでは、層厚を550mm、点火部からストランド長さ50％までを−500mmAqで下方吸引するとともに、該範囲にも加圧フードをさらに設けて、加圧フード内の圧力を500mmAqとし、ストランド長さ80％から排鉱部までを−1000mmAqで下方吸引刷るとともにフード内の圧力を500mmAqとし、ストランド長さ50〜80％の間を−1500mmAqで下方吸引するとともに加圧フード内の圧力を1000mmAqとして加圧した。この場合、ストランド長さ50〜80％の範囲内ではそれ以外の範囲に対して、質量流量比は1.56で、層厚方向の差圧は2500mmAqであった。
実施例２ｃでは、層厚を800mmとし、これ以外の設定は実施例２ａと同じにした。この場合、ストランド長さ50〜80％の範囲内ではそれ以外の範囲に対して、質量流量比は1.52で、層厚方向の差圧は2500mmAqであった。
実施例２ｄでは、層厚を800mmとし、パレットに板状のシンターケーキ支持スタンドをパレット幅方向に均等に４枚平行に設置し、これ以外の設定は実施例２ａと同じにした。この場合、ストランド長さ50〜80％の範囲内ではそれ以外の範囲に対して、質量流量比は1.52で、層厚方向の差圧は2500mmAqであった。
比較例1は、実施例2a〜2dと同じ配合原料を層厚550mm、負圧1500mmAq一定で点火部から排鉱部まで大気を吸引して、配合原料層内は負圧で焼結する従来法で焼結した。
第２表に比較例1と実施例２ａ〜２ｄで得られた焼結鉱の生産率、成品歩留り、RDI、NOx排出量原単位を示す。第２表から分かるように、実施例２ａ〜２ｄでは比較例に対して生産率が著しく向上した。また、従来は生産率が向上すると成品歩留りが低下する傾向があったが、本発明では成品歩留りも向上した。さらに、RDI、JIS-RIとNOx排出量原単位も改善され、操業面及び環境面において優れた効果を発揮できた。
なお、前記公知技術の特公平5-55574号公報との比較を合わせて第２表の続きとして下記表に示す。この表より、本発明の実施例2dでは、焼結鉱の特性として本公知技術の値を凌駕する、極めて良好な特性を有することがわかる。
Figure 0003930570
Figure 0003930570
実施例３
実施例１および実施例２と同様の焼結機を用いた。配合原料は低SiO2焼結鉱の製造を目的として、種々の鉄鉱石及び石灰石、生石灰、蛇紋岩、スケール等の雑原料、返鉱、粉コークスを焼結鉱中のSiO2が4.6mass％、Al2O3が1.85mass％になるように調整し、塩基度は1.9になるように配合した。返鉱配合率は新原料の合計100に対して15％一定、コークス配合率は新原料の合計100に対して3.5％一定とした。比較例、実施例ともに同じ配合とした。
実施例３ｃでは、層厚を550mm、点火部からストランド長さ60％、及びストランド長さ80％から排鉱部までを−500mmAqで下方吸引するとともに、該範囲に加圧フードをさらに設けて、加圧フード内の圧力を500mmAqとし、ストランド長さ60〜80％の間を−1500mmAqで下方吸引するとともに加圧フード内の圧力を1000mmAqとして煙突前の排ガスの一部を酸素濃度を16％に調節して加圧送風した。この場合、ストランド長さ60〜80％の範囲内ではそれ以外の範囲に対して質量流量比は1.56で、層厚方向の差圧は2500mmAqであった。
比較例２は、実施例３ｃと同じ配合原料を層厚550mm、負圧1500mmAq一定で点火部から排鉱部まで大気を吸引して、配合原料層内は負圧で焼結する従来法で焼結した。
第３表に比較例と実施例３ｃで得られた焼結鉱の生産率、成品歩留り、RDI、NOx排出量原単位を示す。第３表から分かるように、実施例３ｃでは比較例に対して生産率が著しく向上した。また、従来は生産率が向上すると成品歩留りが低下する傾向があったが、本発明では成品歩留りも向上した。さらに、RDI、JIS-RIとNOx排出量原単位も改善され、操業面及び環境面において優れた効果を発揮するとともに、低SiO2焼結鉱の製造ができた。
Figure 0003930570
なお、焼結時の負圧の設定や吸引ガスの酸素濃度と吸引時間は上記実施例に限るものではなく、生産性指向やRDI、JIS-RI改善指向、NOx排出抑制指向、排ガス量抑制指向で変化させることができる。
本発明によれば、従来困難であった大幅な配合原料充填層の層厚の増加やパレット移動速度の増加が可能となり、焼結機の生産率を大幅に向上させることができる。さらに、成品歩留りやRDI、JIS-RIが改善され、排ガス量が低減される。このように本発明は両立し難い改善効果を同時にもたらしており、その効果は非常に大きい。Technical field
The present invention relates to a method and a sintering machine for producing sintered ore which is a raw material of a blast furnace production method, and in particular, when a combustion melting zone is shifted from the upper side to the lower side of a pallet of a sintered layer, After obtaining a stratified layer, increase the supply amount of oxygen-containing gas, increase the differential pressure to extremely accelerate the transition speed of the combustion melting zone, increase the production rate and improve product quality and yield The present invention relates to a method for producing sintered ore and a sintering machine for the same.
Conventional technology
For the sintering of iron ore, dwelloid type sintering machines are widely used. This is a raw material packed bed by filling a raw material powder ore with a mixture of raw materials such as limestone and silica and fuel and water such as powdered coke, and mixing and granulating them on a sintered pallet arranged in a caterpillar shape. After the horizontal movement of the sintering pallet and igniting the surface of the packed bed in the ignition furnace, the suction is sucked from below, the fuel such as coke in the blended raw material is burned, and the generated heat is used as the raw material. The powder ore is melted and solidified, and the combustion zone is gradually moved from the surface layer portion to the lower layer portion and sintered, and the sintering time is about 20 to 40 minutes.
Compared to other batch-type sintering machines such as a Green Wald-type sintering machine, the Dwightroid-type sintering machine is a continuous type and is suitable for mass production because of its wide use. The current Dwightroid type sintering machine is upsized and has a width of 5m x length of 100m, but the production rate is 34 to 43t / d / m. 2 Degree.
Here, considering the global resource situation, the supply of massive ore, which is the raw material for the blast furnace manufacturing method, has become conspicuous, and along with this, the price of massive ore has been increasing. Is required. However, in order to increase the production volume of sintered ore, adding a sintering machine or increasing the size of the sintering machine not only requires a large amount of capital investment but also increases the amount of exhaust gas discharged. However, problems such as unfavorable environmental problems occur. For this reason, the productivity improvement of a sintering machine is calculated | required strongly. However, in the production of sintered ore, while maintaining the quality of the product sintered ore required by the blast furnace manufacturing method, the production rate is maximized, the fuel intensity and ignition fuel intensity are minimized, and NOx emissions are minimized. Suppressing operations are required. Therefore, in actual operation, the amount of silica, serpentine, limestone, powdered coke and anthracite added as fuel, and the amount of ignition during ignition within the range to maintain the quality of sintered ore. It is better to reduce the amount of coke oven gas and pulverized coal as fuel.
However, it is not possible to obtain good results by reducing the blending ratio of the auxiliary material and fuel to the sintering raw material, and the amount of ignition fuel, and if they are greatly reduced, the cold strength and RDI of the sintered ore will not be obtained. (Reduction powder reduction rate) deteriorates, or the amount of return ore increases, rather the fuel unit and ignition fuel unit deteriorate, and the NOx conversion rate worsens and NOx emissions increase on the contrary. Become. Also, sintered ore SiO 2 It is also well known that the RDI greatly deteriorates when the value is reduced to 5.0 mass% or less.
In Japanese Patent Publication No. 55-19299, “the first half hood part of the negative pressure is provided in the first half of the upper part of the strand and the second half hood part of the pressure is provided in the second half of the upper part of the strand. If the exhaust gas in the latter half is circulated by the negative pressure, the amount of exhaust gas can be reduced, and the power cost and productivity can be prevented from decreasing. " However, in this method, the part to be sintered in the air in the latter half is covered with a positive pressure hood, the blower following the wind box in the latter half is removed, and the amount of exhaust gas is reduced by the exhaust gas circulation equipment that minimizes equipment costs. The purpose is to actively increase the transition speed of the combustion melting zone in the raw material packed bed to improve productivity. Furthermore, from the disclosed exhaust gas composition, exhaust gas characteristics, drawings, etc., the sintering completion point in this method is the initial stage of the latter half hood part, and cooling is performed on the strand in the remaining range of the latter half part. Unthinkable. Therefore, it is not intended to maximize the production rate by using the entire strand by making the firing completion point as close as possible to the waste mining section.
In Japanese Patent Publication No. 56-19556, “a positive pressure hood that forms a pressure sintering zone is provided, and a negative pressure hood that forms a negative pressure zone by suction at the end of the positive pressure hood on the supply and discharge side is provided. If it is provided, it is disclosed that productivity and operation cost can be improved by a pressure sintering method without requiring an airtight housing covering the entire equipment. " However, this method is a problem in the conventional pressure sintering method, that is, pressure at the raw material supply start end portion into the housing and the sintered ore discharge end portion from within the housing on the moving path of the sintering pallet. The purpose is to prevent the outflow of air into the atmosphere, and there is no mention of anything such as positively increasing the migration rate of the sintered zone in the raw material packed bed to improve productivity. It was. Further, in order to form a negative pressure zone by suction at the end of the supply side, the suction flow rate of this part must be larger than the suction flow rate of the conventional method of sucking the atmosphere. For this reason, the shortage of the high temperature holding time in the firing of the raw material layer upper layer part, which has been a problem in the past, is promoted, and the yield and quality of the raw material layer upper layer part are deteriorated, so that the total productivity is greatly increased. It wasn't.
Japanese Patent Laid-Open No. 61-243131 states that “a hood is provided on the upper surface of the sintered ore on the endless pallet so that a large airtight housing necessary for the pressure sintering method is not required. The cost can be reduced if the inside of the wind box under the endless pallet is made negative pressure. However, compared to the power of the conventional exhaust fan, the purpose is to reduce the total power by combining the push-in and the exhaust fan.To improve the productivity by increasing the transition speed of the combustion zone in the raw material packed bed, etc. It was not mentioned at all. In other words, in the entire strand from the ignition section to the discharge section, in order to make the differential pressure between the upper part and the lower part of the raw material packed bed, which is the air pressure necessary for the process, constant, the inrush fan and the exhaust fan are balanced, While the high-temperature air whose volume has been expanded is exhausted entirely, the room temperature air is pushed in and blown to reduce the total power, and the combustion zone in the raw material packed bed necessary for improving productivity It does not actively increase the migration speed.
In Japanese Patent Publication No. 5-55574, “sintering of sintering raw materials divided into a plurality of wind boxes in the longitudinal direction of the pallet and charged and stacked on the pallet in units of the plurality of divided wind boxes. Corresponding to the reaction, the suction negative pressure is decreased in the initial stage of the sintering reaction compared with the suction negative pressure of the normal operation, and is increased in the middle period to reach the end point of the firing reaction. If it is controlled to decrease at the end of the period, the yield, drop strength (SI), and RDI of the upper part of the sintering bed will be improved, and in addition, the exhaust wind power will be reduced and the sinter ore sensible heat will be more efficient Can be recovered. " However, the RDI and SI of the sinter in the upper part of the sinter bed have already been improved compared to the sinter in the lower part. It is more important to improve the sintered ore. In addition, even if the yield of the upper part of the sintering bed, the quality of the sintered ore, and the reduction of the power consumption can be reduced somewhat, the balance of the air volume sucked in the early, middle and late stages of firing is improved to save energy. There were also adverse effects such as a decrease in yield at the middle layer and a decrease in SI at the lower layer.
In addition, in order to increase the sensible heat recovery energy of the sintered ore, it is necessary to increase the temperature of the product sintered ore at the final stage of firing, and in the height direction of the red tropics (combustion melting zone) in the raw material packed bed The width must be increased. For this reason, the ventilation resistance of the red tropics becomes very large, it is not possible to increase the red tropics transition rate that largely controls the production rate, and adversely affects the production rate at the end of firing, which adversely affects the total production rate. As a result, it was impossible to expect a significant improvement in the production rate.
Furthermore, the suction negative pressure is increased in order to secure the production rate in the middle stage of the calcination reaction, but according to the disclosed explanatory diagram, the exhaust gas flow rate is closer to the first stage of calcination in the middle period than in the conventional method. It is thought that the total production rate does not increase greatly, such as being smaller despite the increase.
Disclosure of the invention
All of the conventional techniques are intended to improve the economical efficiency of the facilities and the operation cost. Therefore, in all cases, it is premised on the current operating conditions in which the blended raw material is filled on a sintered pallet to a layer thickness of about 400 to 600 mm and the fuel in the blended raw material is ignited in an ignition furnace.
The production rate of the sintering machine greatly depends on the transition speed when the combustion melting zone in the raw material packed bed gradually transitions from the surface layer portion to the lower layer portion. The problem in improving the production rate of sintering is that the sintering machine shifts the combustion melting zone in the process of firing from the upper layer to the lower layer of the raw material packed layer in the strand from the ignition part to the exhausting part. The speed is slow. Therefore, if the transition speed of the combustion melting zone is the same as before, increasing the layer thickness of the packed bed and the moving speed of the sintering pallet will increase the length of the sintering machine and the sintering time required for the completion of sintering. Because it increases, the production rate does not improve.
Further, if the transition speed of the combustion melting zone is increased too much, the amount of heat necessary for firing cannot be ensured because it causes insufficient combustion of coke, leading to a decrease in yield and quality. Therefore, securing the amount of heat necessary for the firing reaction and increasing the transition speed of the combustion melting zone are important for significantly improving the production rate of the sintering machine. Furthermore, in the raw material packed bed, the ventilation resistance of the combustion melting zone is large. Therefore, if the thickness of the combustion melting zone in the height direction of the raw material packed bed is minimized, the air permeability is improved and the coke combustion rate is increased. The transition speed of the combustion melting zone can be increased. Thus, controlling the cooling rate of the cooling zone above the combustion melting zone and the transition rate of the combustion melting zone in a well-balanced manner is also important for greatly improving the production rate of the sintering machine.
In general, in order to increase the transition speed of the combustion melting zone, it is conceivable to increase the suction flow rate by increasing the negative pressure of the blower and increase the amount of oxygen supplied to the raw material packed bed.
However, it is necessary to maintain the high temperature holding time of the raw material packed layer upper layer part in order to prevent the yield of the raw material packed layer upper layer part and the quality deterioration of the sintered ore. The transition speed of the combustion melting zone in the previous stage cannot be increased from the current level. In addition, due to the increase in the negative pressure of the blower, gravity and the blowing pressure are superimposed to compress the raw material packed layer and the ventilation is hindered. There is no significant increase in pressure.
On the other hand, low SiO 2 There is a demand for the production of sintered ore, but problems such as the production rate, RDI deterioration, and increased NOx emissions that have become apparent at this time have not been solved.
Accordingly, the present invention provides a method for producing a sintered ore, which can greatly improve the productivity of a sintering machine by increasing the layer thickness of the raw material packed layer and the moving speed of the sintering pallet, and a low SiO 2 It aims at providing the manufacturing method of a sintered ore, and the sintering machine used for these.
The gist of the present invention for achieving the above object is as follows.
(1) A raw material mixture containing raw material ore, solvent and fuel is placed on a pallet of a sintering machine to form a raw material packed layer, and then the raw material packed layer is ignited to cause a sintering reaction from above to below. In a method for producing a sintered ore by: A pressure hood is provided on the raw material packed bed on the sintering pallet to supply an oxygen-containing gas under pressure, and the pressure hood is pressurized to 100 to 3000 mmAq with respect to atmospheric pressure, and below the raw material packed layer From -2000 to -1 mmAq with respect to atmospheric pressure, When the raw material packed layer upper layer part is sufficiently fired, the mass flow rate of the oxygen-containing gas supplied to the raw material packed layer is set to 1.01 to 2.6 of the mass flow rate of the oxygen-containing gas supplied in the range of firing the raw material packed layer upper part. A sintered ore manufacturing method for obtaining a product with excellent product yield and quality, characterized in that the product is sintered after being changed to double.
(2) A raw material mixture containing raw material ore, solvent and fuel is placed on a pallet of a sintering machine to form a raw material packed layer, and then the surface of the raw material packed layer is ignited and a combustion melting zone is formed from above to below. In a method of continuously producing sintered ore while shifting A pressure hood is provided on the raw material packed bed on the sintering pallet to supply an oxygen-containing gas under pressure, and the pressure hood is pressurized to 100 to 3000 mmAq with respect to atmospheric pressure, and below the raw material packed layer From -2000 to -1 mmAq with respect to atmospheric pressure, The mass flow rate of the oxygen-containing gas supplied to the raw material packed layer is changed when the tip of the formation range of the combustion melting zone reaches below the position of 20% of the height of the raw material packed layer from the surface layer of the raw material packed layer. A sintered ore production method for obtaining a product having a good product yield and quality, wherein the sintering is performed by changing the mass flow rate of the oxygen-containing gas supplied to 1.01 to 2.6 times the mass flow rate of a layer to be fired.
(3) A pressurized hood is provided on the raw material packed layer on the sintered pallet to pressurize and supply an oxygen-containing gas within a range of 5 to 95% in the pallet width direction. The method for producing a sintered ore according to any one of (1) and (2), wherein the pressure is 100 to 3000 mmAq.
(4) Out of the raw material packed bed from the upper side to the lower side, the raw material filling in the range after the tip of the combustion melting zone formation range reaches below the position of 20% of the raw material packed bed height from the surface layer of the raw material packed bed Any one of (1) to (3), wherein a pressurized hood for supplying an oxygen-containing gas under pressure is provided on the layer, and the inside of the pressurized hood is pressurized to 100 to 3000 mmAq with respect to atmospheric pressure. A method for producing sinter ore.
(5) The sintering according to any one of (1) to (4), wherein the sintering exhaust gas is circulated through a pressurized hood that pressurizes and supplies an oxygen-containing gas provided on the raw material packed layer. Mining production method.
(6) Sintering is performed using a droidoid sintering machine in which a plurality of plate-like sinter cake support stands are provided substantially parallel to the pallet traveling direction on the sintering pallet (1) To the method for producing a sintered ore according to any one of (5).
(7) 3.9 to 4.9 mass% SiO as a chemical component 2 A method for producing a sintered ore according to any one of (1) to (6), wherein a sintered ore containing is produced.
(8) The method for producing a sintered ore according to any one of (1) to (7), wherein the raw material packed layer has a thickness of 600 to 1500 mm.
(9) In a lower suction type sintering machine in which a plurality of window boxes below the sintered strand are connected in parallel to a suction duct, and a main blower is provided in the suction duct, While providing a pressurized hood for supplying oxygen-containing gas under pressure on the raw material packed layer of the sintering pallet, A sintering machine, further comprising a blower that sucks from a duct within a range of a sintering completion point from 30% of a suction duct length from an ignition part to a discharge part, and discharges the suction duct to the suction duct.
(10) The suction duct in which a plurality of wind boxes at the lower part of the sintered strand are connected in parallel is divided into 30% of the length of the strand from the ignition part to the discharge part and within the range of the sintering completion point and the remaining range. The sintering machine according to (9), wherein each is provided with a blower independently.
(11) Out of the raw material packed bed from the upper side to the lower side, the raw material filling in the range after the tip of the combustion melting zone formation range reaches below the position of 20% of the raw material packed bed height from the surface layer of the raw material packed bed The sintering machine according to (9) or (10), wherein a pressurized hood for supplying an oxygen-containing gas under pressure is provided on the layer.
(12) A pressurizing hood for pressurizing and supplying an oxygen-containing gas is provided within a range of 5 to 95% in the pallet width direction on the raw material packed layer on the sintered pallet (9) To the sintering machine according to any one of (11).
(13) The sintering according to any one of (9) to (12), wherein the sintering exhaust gas is circulated through a pressurized hood that pressurizes and supplies an oxygen-containing gas provided on the raw material packed layer. Machine.
(14) The sintering machine according to any one of (9) to (13), wherein a seal mechanism is provided at a lower end portion of a hood that pressurizes and supplies the oxygen-containing gas.
(15) The structure of the lower suction type sintering machine is characterized in that a plurality of plate-like sinter cake support stands are provided substantially parallel to the pallet traveling direction on the sintering pallet great (14) to (14) ) The sintering machine according to any one of the above.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a sintering machine as a premise of the present invention.
FIG. 2 is a view showing an embodiment of another sintering machine which is a premise of the present invention.
FIG. 3 is a view showing an embodiment of a sintering machine according to Examples 1b to 1e of the present invention.
FIG. 4 is a view showing an embodiment of a sintering machine according to Examples 2a to 2d and 3c of the present invention.
FIG. 5 is a view showing another embodiment of the sintering machine of the present invention.
FIG. 6 is a view showing a sealing mechanism of a pressure hood of the sintering machine according to the present invention.
FIG. 7 is a view showing a plate-like sinter cake support stand of the sintering machine according to the present invention.
FIG. 8 (a) is an explanatory view showing the transition of the combustion melting zone in the pallet according to the present invention. FIG. 8 (b) is a cross-sectional view along the line AA ′ of the combustion melting zone in the pallet according to the present invention. FIG. 8 (c) is an explanatory diagram showing the transition of the combustion melting zone during cooling on the strand according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
In general, a sintered ore is prepared by charging a raw material powder ore, a solvent and a fuel containing a blended raw material onto a pallet of a Dwytroid-type sintering machine to form a raw material packed bed, igniting it in an ignition part, and then containing an oxygen-containing gas. It is manufactured by moving it to the waste mining part while sucking from below. Accordingly, the firing is performed from the upper side to the lower side of the raw material packed layer. However, since it can be expressed in comparison with the strand length direction and is easy to understand, the present invention will be described below using the strand length.
FIG. 8 (a) is an explanatory view showing an example of the raw material packed bed sintering process of the present invention. In this figure, I is an initial raw material zone, II is a wet (water condensation) zone, III is a dry zone, IV is a combustion zone, V is a melting zone, and VI is a sintering zone. FIG. 8 (b) is a cross-sectional view taken along the line AA ′ at the center of FIG. 8 (a). Point B indicates the position closest to the ignition furnace that forms the combustion melting zone in the initial stage of the present invention and changes and increases the supply amount of the oxygen-containing gas in the raw material packed bed, and point C indicates the combustion completion point. Indicates. In a normal operation, in order to use the entire strand efficiently and stably, the operation is performed so that the sintering completion point is constant. When the production volume is important, the operation is to bring the sintering completion point as close as possible to the exhaust side, and when the yield and quality are important, the sintering completion point has one or two margins of the wind box. Is moved closer to the ignition furnace and operated to be constant. However, when cooling is performed on the strand, for example, as shown in FIG. 8 (c), an operation in which the sintering completion point C ′ is changed to the middle portion of the strand is performed. In this case, the supply amount of the oxygen-containing gas may be changed according to the layer thickness or the position in the strand length direction based on the present invention disclosed below. Furthermore, in the following description, an example in which the sintering completion point is at a position where the strand length is 95% from the ignition part is shown. The blowing or suction pressure is shown as a pressure relative to the atmospheric pressure.
The range where the strand length is 30% or less from the ignition part is substantially equivalent to the firing area of the upper part 20% of the raw material packed layer, and the yield and quality of the upper part of the raw material packed layer are generally inferior to those of the middle lower layer part. This is because the coke combustion rate that gives the amount of heat necessary for the firing reaction is insufficient because it is immediately after ignition. Furthermore, it is due to the fact that there is heat dissipated from the surface. Therefore, since it is necessary to secure the amount of heat necessary for the sintering reaction, it is not preferable to increase the transition speed of the combustion melting zone in the firing process of the upper layer portion of the raw material packed layer for reasons such as yield and quality deterioration. .
Therefore, in the present invention, the range of the strand length of 30% or less from the ignition part, which is the firing area of the upper layer part of the raw material packed layer, is the same as the conventional suction negative pressure, the high temperature holding time of the upper part of the raw material packed layer is increased. Since it can ensure, the yield and quality of the upper layer part of a raw material filling layer can be ensured.
In order to positively improve the yield and quality of the upper part of the raw material packed layer, it is only necessary to increase the calorific value of the part. For this purpose, it is preferable to lower the suction negative pressure at the site, strengthen coke segregation at the upper part of the raw material packed layer, or add a breeze to the surface layer portion. In addition, the amount of heat can be applied from the outside of the raw material packed bed. For example, hot air can be sucked into the part, or induction heating by a microwave or the like can be performed.
The range of 30 to 95% of the strand length from the ignition part corresponds to the firing area of the middle and lower layers of the raw material packed layer, and the sintered zone of the upper layer of the raw material packed layer has a low airflow resistance, whereas the raw material packed layer From the middle layer to the lower layer, the thickness of the combustion melt zone having a large ventilation resistance is increased, so that the ventilation resistance is increased. In particular, when the strand length is 50 to 95%, the air permeability is deteriorated and the calorific value is excessive. The mass flow rate of the oxygen-containing gas is controlled by forcibly supplying the mass flow rate of the oxygen-containing gas from above into the combustion melting zone having a large pressure loss within the range from the middle layer to the lower layer (range from the ignition portion to the strand length of 30 to 95%). By increasing the oxygen-containing gas supplied to the raw material packed bed in the strand range excluding the strand by 1.01 to 2.6 times, the coke combustion speed from the middle layer to the lower layer is increased to increase the transition speed of the combustion melting zone, and the combustion melting zone The cooling rate of the upper cooling zone is also increased, and the amount of heat necessary for firing is secured, and the thickness of the combustion melting zone is reduced, thereby improving the air permeability. Thus, controlling the calorific value and air permeability depending on the temperature of the combustion melting zone and the thickness in the height direction of the raw material packed bed is important for improving the production rate of sintering.
In the present invention, the mass flow rate represents the mass of gas flowing per unit time, and the unit is expressed in kg / s or the like. The generally used flow rate indicates a volume flow rate, which represents the volume of gas flowing per unit time, and its unit is m. Three / S etc. If the mass flow rate is the same, the volume flow rate varies with temperature and pressure according to the gas equation of state.
The oxygen-containing gas in the present invention includes not only the air but also exhaust gas discharged from the sintering machine, exhaust gas from other processes, etc., and a mixed gas of air and exhaust gas, oxygen-enriched gas Further, a gas having an oxygen concentration of 12 to 40 vol% is preferable.
Here, the mass flow rate of the oxygen-containing gas supplied to the raw material packed bed within the range of the strand length of 30 to 95% from the ignition unit is the oxygen-containing gas supplied to the raw material packed bed in the strand range excluding the above range. The adjustment to 1.01 to 2.6 times the mass flow rate is that the transition speed of the combustion melting zone hardly changes when the mass flow rate is less than 1.01 times, and the gas flow rate increases too much when the mass flow rate exceeds 2.6 times. This is because it is cooled or the raw material packed layer is consolidated due to an increase in the differential pressure above and below the raw material packed layer and air permeability is hindered. Further, the mass flow rate of the oxygen-containing gas sucked into the raw material packed bed within the range of the strand length of 50 to 85% from the igniter, and the mass of the oxygen-containing gas supplied to the raw material packed bed in the strand range excluding the above range It is particularly preferable to adjust the flow rate to 1.1 to 1.8 times from the viewpoint of improving the productivity of the sintered ore.
In addition, when the atmosphere is sucked in as an oxygen-containing gas to increase the transition speed of the combustion melting zone, the raw material packed bed in the range of the strand length of 30 to 95% from the ignition part is used in order to obtain the prescribed mass flow rate. The differential pressure in the layer thickness direction is preferably 1.1 to 5.0 times the differential pressure in the layer thickness direction of the raw material packed layer in the strand range excluding the above range. Here, in the range of the strand length of 30 to 95%, the ventilation resistance is about 1.5 to 5 times larger than the other ranges. Therefore, if the differential pressure is less than 1.1 times, the effect of promoting the transition speed of the combustion melting zone due to the increase in the ventilation rate is small, and if the differential pressure exceeds 5.0 times, the gas flow rate becomes too large and the cooling rate increases greatly. It is not preferable because the high temperature holding time cannot be secured and the raw material packed layer is consolidated and the air permeability is deteriorated. Further, it is particularly preferable that the differential pressure is 1.2 to 2.0 times in terms of productivity improvement. In addition, it is preferable that the gas supply amount is gradually increased from the ignition part side to the exhausting part side so that the transition speed of the combustion melting zone and the cooling speed are made closer. If the supply amount is increased rapidly, the cooling rate becomes larger than the coke combustion rate for a short period of time, and a part where sufficient calorific heat cannot be maintained is generated. This is because the quality deteriorates.
As mentioned above, increasing the mass flow rate by increasing the differential pressure of the raw material packed bed in the range of 30 to 95% of the strand length from the ignition part greatly improves the production rate of sintered ore, Products with excellent yield and quality can be obtained. When the differential pressure is increased and the gas supply amount is increased, the exhaust gas emission amount of the part is increased accordingly, but since the firing reaction is active and the oxygen consumption efficiency is high, without reducing the oxygen consumption efficiency, Furthermore, since the excessive gas supply amount near the upper layer part and the ore excavation part is suppressed as much as possible, the air volume basic unit can be reduced.
The inventors of the present invention can avoid the deterioration of air permeability due to the consolidation of the raw material packed layer by increasing the mass flow rate of the oxygen-containing gas by combining the lower suction of the raw material packed layer and the pressurization from the upper side, and igniting The mass flow rate of the oxygen-containing gas supplied to the raw material packed bed in the range of 30 to 95% of the strand length from the portion is relative to the mass flow rate of the oxygen-containing gas supplied to the raw material packed bed in the strand range excluding the above range. Combustion by adjusting the pressure difference in the layer thickness direction of the raw material packed layer to 1.01 to 2.6 times, more preferably 1.1 to 5.0 times the differential pressure in the layer thickness direction of the raw material packed layer in the strand range excluding the above range It was found that the transition rate of the melting zone can be increased and the product yield and quality can be improved.
A pressurized hood that covers the top of the raw material packed layer charged on the sintering pallet is provided, the inside of the hood is pressurized, oxygen-containing gas is pressurized and blown from above to the raw material packed layer, and a wind box directly under the pallet The gas is flowed from the upper side to the lower side of the raw material packed layer by controlling the differential pressure between the upper side of the raw material packed layer and the lower side of the raw material packed layer. In this way, in the present invention, the static pressure in the raw material packed layer can be increased compared to the static pressure in the raw material packed layer that is conventionally formed by sucking the lower surface of the raw material packed layer from below at atmospheric pressure. If the conventional method of sucking air and the differential pressure above and below the raw material packed bed are the same, in the present invention, the mass flow rate supplied into the raw material packed bed can be increased as compared with the conventional method, and the gas density in the raw material packed bed Can be made larger than before. As a result, the supply amount of the oxygen-containing gas into the raw material packed bed is increased, the coke combustion rate in the raw material packed layer is increased, the calorific value of the combustion melting zone is increased, the transition rate is increased, and the cooling is increased. The transition speed of the belt can also be accelerated. If the static pressure in the raw material packed bed increases, the heat transfer rate between the gas and the solid also increases, and the transition of the combustion melting zone and the cooling of the cooling zone can be promoted.
Further, in the forced blow from above, the gas can be supplied to the combustion melting zone where the reaction occurs by forming a uniform gas flow through the sintered zone having a low ventilation resistance. On the other hand, in the gas supply by suction from the lower side, the wet zone having a relatively large ventilation resistance and the large ventilation resistance in the combustion melting zone in which the calcination reaction occurs are preferentially selected. Since it flows, a non-uniform gas flow is formed, and the reaction efficiency between gas and solid is likely to deteriorate. Therefore, the gas flow pushed in from the upper side forms a uniform gas flow with respect to the gas flow by the suction from the lower side, so that the oxygen consumption efficiency is improved and the air volume basic unit necessary for the production of the sintered ore can be reduced.
Furthermore, if the differential pressure of the raw material packed bed within the range of 30 to 95% of the strand length is increased, the effect of increasing the mass flow rate due to the increased differential pressure and the effect of increasing the static pressure level are added. It becomes very large.
In order to increase the mass flow rate and static pressure level in the raw material packed bed from the conventional method, the inside of the pressure hood provided above the raw material packed bed is pressurized in the range of 100 to 3000 mmAq, and −2000 from the lower side of the raw material packed bed. Supply gas at ~ -1mmAq. If the pressure above the raw material packed bed is less than 100 mmAq, the productivity will not change much compared to conventional operations, and if the pressure above the raw material packed layer exceeds 3000 mmAq, the differential pressure above and below the raw material packed layer will be too large. In addition, the force for compressing the raw material packed layer is increased due to the superposition of gravity and the blowing pressure, which is not preferable because the raw material packed layer is consolidated and the air permeability is deteriorated. Further, as the pressure is increased, air leakage from between the hood and the object in contact with the hood increases, which causes problems such as difficulty in sealing and the need for large-scale equipment. The suction negative pressure of the wind box directly under the pallet is set in the range of −2000 to −1 mmAq depending on the setting of the differential pressure pattern above and below the raw material packed layer. If it is less than −2000 mmAq, even if the upper part of the raw material packed bed is pressurized, the static pressure level in the raw material packed layer does not become much higher than in the conventional method. There is little increase in heat speed. This is because if it exceeds −1 mmAq, the exhaust gas cannot be sucked.
The upper and lower differential pressures of the raw material packed layer within the strand length of 30 to 95% from the ignition part depend on the layer thickness and pallet speed, but are preferably set to 1000 to 3000 mmAq. This is because if the differential pressure above and below the raw material packed bed is less than 1000 mmAq, the differential pressure in the raw material packed layer is smaller than that of the conventional method, and the adverse effect of decreasing the gas flow rate is greater than the effect of increasing the static pressure. . It is not preferable that the differential pressure in the raw material packed layer exceeds 3000 mmAq because gravity and the blowing pressure are superimposed to compress the raw material packed layer, and the raw material packed layer becomes consolidated and air permeability deteriorates.
Oxygen sucked into the raw material packed bed in the range of 30 to 95% of the strand length from the ignition portion by providing a pressurized hood divided into a plurality in the strand length direction in the entire range from the ignition portion to the discharge portion The mass flow rate of the containing gas is 1.01 to 2.6 times the mass flow rate of the oxygen-containing gas supplied to the raw material packed layer in the strand range excluding the above range, and the differential pressure in the layer thickness direction of the raw material packed layer is within the above range. It can be easily adjusted to 1.1 to 5.0 times the differential pressure in the layer thickness direction of the raw material packed layer in the strand range excluding.
As described above, the range of the strand length of 30% from the ignition part is required to keep the high temperature holding time in order to prevent the yield of the raw material layer upper layer part and the quality deterioration of the sintered ore. Can not increase the transition speed of the combustion zone from the present. In the case of a conventional layer thickness of 400 to 600 mm, the range of 30% or less of the strand length from the igniter section is 100% to 1000 mmAq from the upper part of the raw material packed layer, and suction suction is performed to suck and exhaust from the wind box directly under the pallet. If the pressure is -1000 to -1 mmAq and the differential pressure above and below the raw material packed layer is adjusted to 300 to 2000 mmAq, the differential pressure is the same or smaller than the differential pressure of the conventional downward suction, ensuring high temperature holding time Alternatively, the amount of heat necessary for firing can be obtained. At this time, since the oxygen supply rate of the upper layer of the raw material packed layer is increased, the effect of improving the coke combustibility similar to that of oxygen enrichment can be obtained, and the yield and quality of the upper layer of the raw material packed layer can be further improved. Can do.
However, since the effect of increasing the production rate by normal downward suction is relatively small except for the raw material packed layer within the strand length range of 30 to 95%, the pressure hood is 30 to 95% of the strand length from the ignition part. It is preferable from the point of simplification of an installation to provide in the range. Furthermore, if the pressure hood is divided into a plurality in the strand length direction, the mass flow rate can be changed stepwise from the ignition part side to the discharge part side.
Furthermore, since the ventilation resistance is not large in the vicinity of the side wall within 5% from the pallet side wall of the raw material packed bed in the pallet width direction as compared with the central part, the transition speed of the combustion melting zone is high. For this reason, if a pressurized hood is provided in the range of 5 to 95% in the width direction of the raw material packed bed and the gas is supplied so that the transition speed of the combustion melting zone is uniform in the width direction, the transition of the combustion melting zone The effect of increasing speed is even greater.
The pressure hood is installed above the moving sintering pallet, but it is preferable to provide a seal mechanism at the lower end of the pressure hood to avoid air leakage. As shown in FIG. 6, as the sealing mechanism, the sheet 24 provided at the lower end of the hood is pressed against the upper surface of the raw material filling layer 7 by the internal pressure of the pressure hood 19, and the raw material filling layer is moved along with the movement of the pallet. 7 is preferable. In addition, a structure provided with several stages of the sealing mechanism 23, a structure in which air is blown from the outside of the pressurized hood 19 between the pressurized hood 19 and the raw material packed layer 7, and a sealing mechanism utilizing the side wall portion of the pallet 6 However, the present invention is not limited to these examples.
A gas having an oxygen concentration adjusted to less than 12 to 21 vol% is supplied into a pressurized hood within a range of strand length of 30 to 95% from the ignition unit, particularly preferably within a range of strand length of 60 to 80%. Baking promotes the formation of magnetite, which is good for improving RDI, and also suppresses the oxidation of nitrogen in coke to NOx, which is effective in improving RDI and suppressing NOx generation. In order to adjust the oxygen concentration in the pressurized hood to less than 12 to 21 vol%, a part of the exhaust gas from the sintering machine can be circulated and used. In this case, the capacity of the blower for exhaust gas circulation is designed in consideration of the suction negative pressure, the air volume, the size of the equipment, etc. so that the air quantity supplied from above the raw material packed bed can be sent to the exhaust gas treatment equipment.
When the oxygen concentration is less than 21 vol%, RDI is improved by promoting the formation of magnetite, and when the oxygen concentration is low, oxidation of nitrogen in the coke to NOx is suppressed, but when it is less than 12 vol%, productivity decreases. Since the adverse effect of the above becomes remarkable, the oxygen concentration is preferably 12 vol% or more and less than 21 vol%. In particular, when the oxygen concentration is less than 18 vol%, the effects of improving RDI and suppressing NOx generation become more prominent.
By supporting the sinter cake during firing using a sintering machine described in JP-A-4-168234, in which a plurality of plate-like sinter cake support stands are installed in the width direction parallel to the pallet traveling direction. The load of the sinter cake is no longer applied to the lower layer portion of the raw material packed layer, the air permeability of the lower layer portion of the raw material packed layer is improved, and the production rate is greatly improved. Furthermore, since the load of the sinter cake is reduced, the differential pressure between the upper and lower layers of the raw material packed bed can be increased, and the production rate can be further improved. An example of a sinter cake support stand is shown in FIG. The optimum number of plate-shaped sinter cake support stands 21 depends on the size of the pallet 6, but for example, a pallet with a width of 4 m and a length of 2 m, and a sintering machine with a raw material packed layer thickness of 500 to 600 mm, has 2 to 10 sheets. And the height is preferably 200 to 400 mm. The larger the number of sinter cake support stands, the more effective the support effect is for the sinter cake. However, when the number of sheets exceeds 10, the volume occupied by the sinter cake support stand increases, and conversely, the adverse effect on the production rate starts to become apparent, and the production rate is lowered. When the sinter cake is supported on the sinter cake support stand, the air permeability is further improved, the coke combustion rate increases, the amount of CO generated increases, and the resulting reaction to reduce the generated NO with CO gas becomes active , NOx generation is also suppressed. In this way, by installing a plurality of sinter cake support stands in the present invention, it is possible to simultaneously realize the suppression of NOx generation, which has been difficult to achieve at the same time, the improvement of the production rate, the improvement of the product yield, and the improvement of the sinter quality.
The present invention is SiO 2 Low SiO containing 3.9-4.9 mass% 2 Particularly effective for the production of sintered ore is SiO 2 When 4.9 mass% or less, the ratio of limestone decreases and CaO and SiO 2 This is because the deterioration of the production rate and RDI begins to become remarkable due to the influence of the decrease in the main component of slag, and if it is less than 3.9 mass%, the present invention cannot improve the deterioration of the production rate and RDI.
According to the present invention, among the strands from the ignition part to the discharge part, the mass flow rate of the oxygen-containing gas sucked into the raw material packed layer within the strand length of 30 to 95% from the ignition part is excluded from the above range. This can be increased up to 2.6 times the mass flow rate of the oxygen-containing gas sucked into the raw material packed bed in the range, so in the conventional sintering operation with a layer thickness of 400 to 600 mm, the moving speed of the sintering pallet is conventional Can be increased to more than 2.0 times. Furthermore, it is possible to make the layer thickness of the raw material packed layer 600 to 1500mm, which is more than twice that of the conventional one, thereby improving the production rate of the sintering machine up to 2.0 times the conventional sintering production rate. It is possible to improve the product yield and quality, and reduce the exhaust gas volume per unit. In addition, the production rate can be kept constant, the product yield and the quality of sintered ore can be improved, and the exhaust gas volume per unit can be reduced.
In addition, as the suction negative pressure sucked from below the raw material packed bed is reduced, the inflow of outside air from the sliding portion between the pallet and the wind box can be reduced. Therefore, since the air volume effective for firing is increased and the air leakage is reduced, the productivity is further improved and the basic air volume can be reduced.
As a sintering machine used in the method for producing sintered ore according to the present invention, a blower is further added to a conventional structure in which a plurality of window boxes below a sintered strand are connected in parallel to a suction duct, and a main blower is provided in the suction duct. In addition, by sucking from any point within the range of 30 to 95% of the suction duct length from the ignition part to the discharge part and discharging to the suction duct, the strand length of 30 to 95% from the ignition part The mass flow rate of the oxygen-containing gas supplied to the raw material packed bed within the range is 1.01 to 2.6 times the mass flow rate of the oxygen-containing gas sucked into the raw material packed layer in the range of the strand excluding the range, and further the raw material packed bed The differential pressure in the layer thickness direction can be adjusted to 1.1 to 5.0 times the differential pressure in the layer thickness direction of the raw material packed layer in the strand range excluding the above range.
Further, a structure in which the suction duct is divided into a strand length of 30 to 95% from the ignition portion and the remaining range and a blower is installed independently is preferable in terms of adjusting mass flow rate and differential pressure. Three blowers may be provided for the front, middle, and rear stages of the strand, but the front and rear stages do not need to change the differential pressure, so the front and rear stages are connected, and the middle stage within the strand length range of 30 to 95%. It is preferable to use two aircraft for use and other ranges.
In the case of combining pressurization from above, it is preferable to provide a hood on the material filling layer to be pressurized, pressurize the inside of the hood, and measure the pressure in the hood and the pressure in the window box below. Furthermore, it is desirable to provide a seal structure between the hood and the raw material packed layer and / or between the hood and the pallet.
Example
The present invention will be described in more detail with reference to Examples 1, 2, and 3.
Sintered area 500m 2 Then, a part of the actual machine sintering machine with a sintering pallet width of 5 m was remodeled, and the operation was carried out for 7 days per level.
Example 1
FIG. 3 is a view showing an embodiment of the sintering machine of the present invention. The sintered blending raw material 1 is continuously supplied from the surge hopper 2 through the drum feeder 3 and the raw material charging device 5 onto the pallet 6 and laminated as a raw material packed layer 7 on the pallet 6 in layers. During this time, the sprocket 4 on the raw material supply side is rotated to move the pallet 6 at a predetermined speed, and a plurality of windboxes 8 provided on the lower side of the pallet 6, the main duct 9, and the exhaust gas dust collector 10 are used by the blower 11. The air is taken in and exhaust gas is discharged from the chimney 12. Further, a sub duct 13 is connected to a part of the main duct 9, and is sucked by the blower 15 through the exhaust gas dust collector 14, and the exhaust gas is returned to the main duct 9. The exhaust gas taken in by the blower 15 can be discharged from the chimney 12. The main duct 9 is preferably provided with a damper 16 for adjusting the negative pressure in the duct.
The ignition furnace 27 is used to ignite the upper surface of the raw material packed bed 7, and the speed control is performed so that the sintering reaction is completed over the entire layer while the raw material packed bed 7 on the pallet 6 reaches the exhausting section. Is done. From the front of the chimney 12, the exhaust gas can be circulated to the pressurized hood 19 by the blower 18 and air can be mixed at the same time. When pressurizing the inside of the pressurizing hood 19, a hood internal pressure is maintained by providing a seal mechanism 23 as shown in FIG. 6 between the raw material packed layer surface layer portion and the lower end portion of the hood. The length in the pallet traveling direction and the length in the pallet width direction can be freely set. Furthermore, in this apparatus, the raw material filling layer 7 can be filled with a thickness of 600 to 1500 mm, which is thicker than before.
The raw material is low SiO 2 Without specially aiming at the production of sintered ore, conventional iron and limestone, quicklime, serpentine, miscellaneous raw materials such as scales, return ore, and fine coke are mixed with SiO in sintered ore. 2 5.8 mass%, Al 2 O Three Was adjusted to 1.8 mass%, and the basicity was adjusted to 1.7. The ratio of return ore mix is 15% constant for the total of 100 new raw materials, and the coke mix ratio is 4.2% constant for the total of 100 new raw materials. The same formulation was used for both the comparative example and the example.
After blending the blended raw material with powdered or coke, water was added, mixed with a mixer, granulated, and charged into a sintering machine. In operation, the pallet speed was adjusted so that the sintering completion point was just before the mining section.
In Example 1b, the layer thickness was 550 mm, the portion from the ignition portion to the discharge portion was sucked downward at −1000 mmAq, and the inside of the pressure hood above the raw material packed layer between strand lengths of 30 to 95% was pressurized to 1500 mmAq. . In this case, the mass flow rate ratio was 1.27 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 95% with respect to the other ranges.
In Example 1c, the layer thickness is 550 mm, the length from the ignition portion to the strand length of 30%, and the length from the strand length of 95% to the discharge portion is −500 mmAq, and the pressure hood is further continued in this range. The pressure in the pressure hood was increased to 500 mmAq, the strand length of 30 to 95% was sucked downward at −1000 mmAq, and the pressure in the pressure hood was increased to 2000 mmAq. In this case, the mass flow ratio was 1.77 and the differential pressure in the layer thickness direction was 3000 mmAq with respect to the other ranges within the strand length of 30 to 95%.
In Example 1d, the layer thickness is 550 mm, the portion from the ignition part to the discharge part is sucked downward at −1000 mmAq, and the strand length is 50 to 90% in the pressure hood provided in the range of 10 to 90% in the pallet width direction. The exhaust gas before the chimney was circulated, the oxygen concentration was adjusted to 18 vol%, and the pressure was increased to 1500 mmAq. In this case, the mass flow rate ratio was 1.27 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 90% with respect to the other ranges.
In Example 1e, a plate thickness of sinter cake support stunts was installed in parallel to the pallet width direction in parallel to the pallet width direction, and the plate thickness was 550 mm, and the suction portion to the discharge portion was sucked downward at −1000 mmAq, and the strand length The inside of the pressure hood provided in the range of 10 to 90% of the pallet width direction of 50 to 90% was pressurized to 1500 mmAq. In this case, the mass flow rate ratio was 1.27 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 90% with respect to the other ranges.
In Example 1f, the layer thickness was 800 mm, and the other settings were the same as in Example 1e. In this case, the mass flow rate ratio was 1.27 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 90% with respect to the other ranges.
In the comparative example, the same blended raw material as in the example was sintered by a conventional method in which the layer thickness was 550 mm, the negative pressure was 1500 mmAq constant and the atmosphere was sucked from the ignition part to the exhausting part, and the blended raw material layer was sintered at a negative pressure. .
Table 1 shows the production rate, product yield, RDI, and NOx emission basic unit of the sintered ore obtained in Comparative Example 1 and Examples 1b to 1f. Here, the NOx emission basic unit is represented by the product of the exhaust gas air volume and the NOx concentration in the exhaust gas. As can be seen from Table 1, in Examples 1b to 1f, the production rate was remarkably improved compared to the comparative example. Conventionally, when the production rate is improved, the product yield tends to decrease. However, in the present invention, the product yield is also improved. Furthermore, RDI, JIS-RI (final reduction rate according to JIS standard) and NOx emission basic unit have been improved, and excellent effects have been demonstrated in terms of operation and environment.
Figure 0003930570
Example 2
4 and 5 are diagrams showing another embodiment of the sintering machine of the present invention. The difference from the embodiment shown in FIG. 3 is that the main duct 9 is completely divided and independent. This is the point that blowers 11 and 15 are provided. Further, a blower 29 can be provided. When a plurality of pressure patterns are set in the strand length direction, a plurality of blowers may be provided as described above.
The blended raw materials were the same as those in Example 1, and the operation was performed by adjusting the pallet speed so that the completion point of sintering was the exhausting part.
In Example 2a, the layer thickness is 550 mm, the length from the ignition part to the strand length of 50% is −1000 mmAq, the area from the ignition part to 80% of the strand length to the discharge portion is suctioned downward at −1500 mmAq, The air was opened to the atmosphere, and the strand length of 50 to 80% was sucked downward at −500 mmAq, and the pressure in the pressure hood was increased to 2000 mmAq. In this case, the mass flow rate ratio was 1.52 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 80% with respect to the other ranges.
In Example 2b, the layer thickness is 550 mm, the length from the ignition part to the strand length of 50% is sucked downward at −500 mmAq, a pressure hood is further provided in this range, and the pressure in the pressure hood is 500 mmAq. From the 80% strand length to the drainage part, the lower suction is printed at -1000mmAq and the pressure in the hood is 500mmAq. Between the strand lengths of 50-80%, the lower suction is performed at -1500mmAq and the pressure in the pressurized hood is reduced. Pressure was applied as 1000 mmAq. In this case, the mass flow rate ratio was 1.56 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 80% with respect to the other ranges.
In Example 2c, the layer thickness was 800 mm, and the other settings were the same as in Example 2a. In this case, the mass flow rate ratio was 1.52 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 80% with respect to the other ranges.
In Example 2d, the layer thickness was set to 800 mm, and four plate-like sinter cake support stands were installed in parallel in the pallet width direction on the pallet, and the other settings were the same as in Example 2a. In this case, the mass flow rate ratio was 1.52 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 50 to 80% with respect to the other ranges.
Comparative Example 1 is a conventional method in which the same blending raw material as in Examples 2a to 2d has a layer thickness of 550 mm, a negative pressure of 1500 mmAq is constant and the atmosphere is sucked from the ignition part to the exhausting part, and the blending raw material layer is sintered at a negative pressure. Sintered with.
Table 2 shows the production rate, product yield, RDI, and NOx emission basic unit of the sintered ore obtained in Comparative Example 1 and Examples 2a to 2d. As can be seen from Table 2, in Examples 2a to 2d, the production rate was remarkably improved compared to the comparative example. Conventionally, when the production rate is improved, the product yield tends to decrease. However, in the present invention, the product yield is also improved. Furthermore, RDI, JIS-RI and NOx emission basic unit have been improved, and excellent effects have been demonstrated in terms of operation and environment.
In addition, the following table is shown as a continuation of Table 2 together with a comparison with Japanese Patent Publication No. 5-55574. From this table, it can be seen that Example 2d of the present invention has extremely good characteristics that surpass the value of the known technique as the characteristics of the sintered ore.
Figure 0003930570
Figure 0003930570
Example 3
The same sintering machine as in Example 1 and Example 2 was used. The raw material is low SiO 2 For the purpose of manufacturing sintered ore, various raw materials such as iron ore and limestone, quicklime, serpentine, scales, etc. 2 4.6 mass%, Al 2 O Three Was adjusted to 1.85 mass%, and the basicity was adjusted to 1.9. The ratio of return ore mix was 15% constant for the total of 100 new raw materials, and the coke mix ratio was fixed at 3.5% for the total of 100 new raw materials. The same formulation was used for both the comparative example and the example.
In Example 3c, the layer thickness is 550 mm, the length from the ignition part to the strand length of 60%, and the length of the strand from 80% to the discharge part is sucked downward at −500 mmAq, and a pressure hood is further provided in the range. The pressure in the pressurized hood is 500 mmAq, the strand length of 60 to 80% is sucked downward at −1500 mmAq, and the pressure in the pressurized hood is 1000 mmAq to reduce the oxygen concentration of the exhaust gas before the chimney to 16%. The air pressure was adjusted and blown. In this case, the mass flow rate ratio was 1.56 and the differential pressure in the layer thickness direction was 2500 mmAq within the range of the strand length of 60 to 80% with respect to the other range.
In Comparative Example 2, the same raw material as in Example 3c is baked by a conventional method in which the atmosphere is sucked from the ignition part to the exhausting part with a constant layer thickness of 550 mm and negative pressure of 1500 mmAq, and the inside of the raw material layer is sintered under negative pressure. I concluded.
Table 3 shows the production rates, product yields, RDI, and NOx emission basic units of the sintered ore obtained in Comparative Example and Example 3c. As can be seen from Table 3, in Example 3c, the production rate was remarkably improved compared to the comparative example. Conventionally, when the production rate is improved, the product yield tends to decrease. However, in the present invention, the product yield is also improved. In addition, RDI, JIS-RI and NOx emission basic unit have been improved, and it has excellent effects in terms of operation and environment, and low SiO. 2 Sintered ore could be manufactured.
Figure 0003930570
Note that the negative pressure setting during sintering and the oxygen concentration and suction time of the suction gas are not limited to those in the above example, but are directed to productivity, RDI, JIS-RI improvement, NOx emission suppression, exhaust gas volume reduction Can be changed.
According to the present invention, it is possible to greatly increase the layer thickness of the mixed raw material packed layer and increase the pallet moving speed, which has been difficult in the past, and to greatly improve the production rate of the sintering machine. Furthermore, the product yield, RDI, and JIS-RI are improved, and the amount of exhaust gas is reduced. As described above, the present invention brings about an improvement effect that is difficult to achieve at the same time, and the effect is very large.

Claims (15)

原料粉鉱石と溶剤と燃料とを含む配合原料を焼結機のパレット上に装入して原料充填層を形成した後、原料充填層表層に点火して上方から下方に焼結反応させることによって焼結鉱を製造する方法において、前記焼結パレット上の原料充填層の上に酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧するとともに、原料充填層の下方から大気圧に対して−2000〜−１mmAqで吸引するとともに、原料充填層上層部を十分に焼成した時点で、原料充填層に供給する酸素含有ガスの質量流量を、該原料充填層上層部を焼成する範囲において供給する酸素含有ガスの質量流量の1.01〜2.6倍に変更して焼結することを特徴とする成品歩留りおよび品質の優れた成品を得る焼結鉱製造方法。By charging the raw material packed ore, solvent and fuel blended raw material onto the pallet of the sintering machine to form the raw material packed layer, and then igniting the raw material packed layer surface layer to cause a sintering reaction from above to below In the method for producing a sintered ore, a pressurized hood for supplying an oxygen-containing gas under pressure is provided on the raw material packed bed on the sintering pallet, and the inside of the pressurized hood is adjusted to 100 to 3000 mmAq with respect to atmospheric pressure. The mass flow rate of the oxygen-containing gas supplied to the raw material packed layer at the time of pressurization and suction from −2000 to −1 mmAq with respect to atmospheric pressure from the lower side of the raw material packed layer and sufficiently firing the upper layer of the raw material packed layer Is obtained by changing the mass flow rate of the oxygen-containing gas to 1.01 to 2.6 times the mass flow rate of the oxygen-containing gas supplied in the range in which the upper layer portion of the raw material packed layer is fired. Mining production method. 原料粉鉱石と溶剤と燃料とを含む配合原料を焼結機のパレット上に装入して原料充填層を形成した後、原料充填層表層に点火して上方から下方に燃焼溶融帯を移行させながら連続的に焼結鉱を製造する方法において、前記焼結パレット上の原料充填層の上に酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧するとともに、原料充填層の下方から大気圧に対して−2000〜−１mmAqで吸引するとともに、燃焼溶融帯の形成範囲の先端が原料充填層の表層から原料充填層高さの20％の位置より下方に達した時点で、原料充填層に供給する酸素含有ガスの質量流量を、該原料充填層を焼成する範囲において供給する酸素含有ガスの質量流量の1.01〜2.6倍に変更して焼結することを特徴とする成品歩留りおよび品質の優れた成品を得る焼結鉱製造方法。A raw material mixture containing raw material ore, solvent and fuel is placed on a pallet of a sintering machine to form a raw material packed layer, and then the surface of the raw material packed layer is ignited to shift the combustion melting zone from above to below. In the method for continuously producing sintered ore, a pressurized hood for supplying an oxygen-containing gas under pressure is provided on the raw material packed bed on the sintering pallet, and the inside of the pressurized hood is adjusted to atmospheric pressure. While pressurizing to 100 to 3000 mmAq and sucking at −2000 to −1 mmAq with respect to the atmospheric pressure from below the raw material packed bed, the tip of the formation range of the combustion melting zone is the height of the raw material packed bed from the surface layer of the raw material packed bed. When reaching below the 20% position, the mass flow rate of the oxygen-containing gas supplied to the raw material packed bed is changed to 1.01 to 2.6 times the mass flow rate of the oxygen-containing gas supplied within the firing range of the raw material packed bed. Product yield and sintering And a method for producing sintered ore to obtain products with excellent quality. 前記焼結パレット上の原料充填層の上で、パレット幅方向の５〜95％の範囲内に酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧することを特徴とする請求の範囲１または２に記載の焼結鉱製造方法。On the raw material packed layer on the sintered pallet, a pressure hood is provided for supplying oxygen-containing gas under pressure in a range of 5 to 95% in the pallet width direction, and the pressure hood is subjected to atmospheric pressure. The method for producing a sintered ore according to claim 1 or 2 , wherein the pressure is increased to 100 to 3000 mmAq. 前記原料充填層の上方から下方のうち、燃焼溶融帯の形成範囲の先端が原料充填層の表層から原料充填層高さの20％の位置より下方に達した以降の範囲の原料充填層の上に、酸素含有ガスを加圧供給する加圧フードを設け、該加圧フード内を大気圧に対して100〜3000mmAqに加圧することを特徴とする請求の範囲１から３のいずれかに記載の焼結鉱製造方法。Of the raw material packed bed in the range from the upper side to the lower side of the raw material packed layer, after the tip of the formation zone of the combustion melting zone has reached below 20% of the raw material packed layer height from the surface layer of the raw material packed layer A pressurizing hood that pressurizes and supplies an oxygen-containing gas is provided, and the inside of the pressurizing hood is pressurized to 100 to 3000 mmAq with respect to atmospheric pressure, according to any one of claims 1 to 3 . Sinter ore manufacturing method. 前記原料充填層の上に設けた酸素含有ガスを加圧供給する加圧フードに焼結排ガスを循環させることを特徴とする請求の範囲１から４のいずれかに記載の焼結鉱製造方法。The sintered ore production method according to any one of claims 1 to 4 , wherein the sintered exhaust gas is circulated in a pressurized hood that pressurizes and supplies an oxygen-containing gas provided on the raw material packed bed. 前記焼結パレットのグレート上にパレット進行方向にほぼ平行に板状のシンターケーキ支持スタンドを複数枚設けたドワイトロイド式焼結機を用いて焼結することを特徴とする請求の範囲１から５のいずれかに記載の焼結鉱製造方法。 5 according to Claim 1, characterized in that sintering using a Dwight Lloyd type sintering machine provided with a plurality of sinter cake supporting stand plate shaped substantially parallel to the pallet advancing direction on the Great the sintering pallet The method for producing a sintered ore according to any one of the above. 化学成分として3.9〜4.9mass％のSiO2を含む焼結鉱を製造することを特徴とする請求の範囲１から６のいずれかに記載の焼結鉱製造方法。Sinter manufacturing method according to any one of the range 1 6 of claims, characterized by producing a sintered ore containing SiO 2 of 3.9～4.9Mass% as chemical components. 前記原料充填層の層厚を600〜1500mmとすることを特徴とする請求の範囲１から７のいずれかに記載の焼結鉱製造方法。The method for producing a sintered ore according to any one of claims 1 to 7 , wherein the raw material packed layer has a layer thickness of 600 to 1500 mm. 焼結ストランド下部の複数のウインドボックスを吸引ダクトに並列に接続し、該吸引ダクトにメインブロアーを設けた下方吸引式の焼結機において、焼結パレットの原料充填層の上に酸素含有ガスを加圧供給する加圧フードを設けるとともに、点火部から排鉱部までの吸引ダクト長さの30％から焼結完了点の範囲内のダクトから吸引し、かつ該吸引ダクトに排出するブロアーをさらに設けたことを特徴とする焼結機。In a lower suction type sintering machine in which a plurality of window boxes below the sintered strand are connected in parallel to a suction duct and a main blower is provided in the suction duct , an oxygen-containing gas is placed on the raw material packed layer of the sintering pallet. A pressure hood is provided to supply pressure , and a blower that sucks from the duct within the range of the sintering completion point from 30% of the suction duct length from the ignition section to the discharge section and discharges to the suction duct is further provided. A sintering machine characterized by being provided. 前記焼結ストランド下部の複数のウインドボックスを並列に接続した吸引ダクトを、点火部から排鉱部までのストランド長さ30％から焼結完了点の範囲内と残りの範囲に分割し、各々独立してブロアーを設けたことを特徴とする請求の範囲９に記載の焼結機。 Wherein the sintering the sintering strand bottom of the suction duct connecting a plurality of wind boxes in parallel, divided from the strand length of 30% from the igniter to Haikou portion range and the remaining range of the sintering completion point, each independently The sintering machine according to claim 9, further comprising a blower. 前記原料充填層の上方から下方のうち、燃焼溶融帯の形成範囲の先端が原料充填層の表層から原料充填層高さの２０％の位置より下方に達した以降の範囲の原料充填層の上に、酸素含有ガスを加圧供給する加圧フードを設けたことを特徴とする請求の範囲９または10に記載の焼結機。Above the raw material packed bed, from above the raw material packed bed, the top of the raw material packed bed in the range after the tip of the formation zone of the combustion melting zone has reached below 20% of the raw material packed bed height from the surface of the raw material packed bed. The sintering machine according to claim 9 or 10 , further comprising a pressurizing hood for supplying an oxygen-containing gas under pressure. 前記焼結パレット上の原料充填層の上で、パレット幅方向の５〜95％の範囲内に酸素含有ガスを加圧供給する加圧フードを設けたことを特徴とする請求の範囲９から11のいずれかに記載の焼結機。On raw material packed layer on the sintered pallet, from the scope 9 claims, characterized in that a pressure hood pressure supply oxygen-containing gas in the range from 5 to 95 percent of the pallet width direction 11 A sintering machine according to any one of the above. 前記原料充填層の上に設けた酸素含有ガスを加圧供給する加圧フードに焼結排ガスを循環させることを特徴とする請求の範囲９から12のいずれかに記載の焼結機。Sintering machine according to any one of claims 9 to 12 claims, characterized in that circulating sintering exhaust gas an oxygen-containing gas which is provided on the raw material packed layer in the pressure supplying pressurized hood. 前記酸素含有ガスを加圧供給するフードの下端部にシール機構を設けたことを特徴とする請求の範囲９から13のいずれかに記載の焼結機。The sintering machine according to any one of claims 9 to 13 , wherein a sealing mechanism is provided at a lower end portion of a hood for pressurizing and supplying the oxygen-containing gas. 下方吸引式焼結機の構造が、焼結パレットのグレート上のパレット進行方向にほぼ平行に板状のシンターケーキ支持スタンドを複数枚設けたことを特徴とする請求の範囲９から14のいずれかに記載の焼結機。Structure of the lower suction type sintering machine, either from the scope 9 claims, characterized by comprising a plurality of sinter cake supporting stand substantially parallel to the plate to the pallet advancing direction on the Great sintering pallets 14 The sintering machine described in 1.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103033064A (en) * 2012-12-28 2013-04-10 北京世纪源博科技股份有限公司 Device for recovering waste heat of sintering flue gas

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101300366B (en) * 2005-10-31 2011-01-05 杰富意钢铁株式会社 Method for producing sintered ore and sintering machine therefor
AT503199B1 (en) * 2006-01-19 2008-02-15 Voest Alpine Ind Anlagen METHOD FOR SINTERING ON A SINTERING MACHINE
JP4590001B2 (en) * 2008-02-27 2010-12-01 新日本製鐵株式会社 Method for producing sintered ore and sintering machine
JP5488209B2 (en) * 2010-06-02 2014-05-14 新日鐵住金株式会社 Method for producing sintered ore, design method for sinter cake support stand, and method for determining layer thickness of raw material packed bed
CN101881559B (en) * 2010-07-22 2011-11-16 张健 Novel energy-saving sintering machine
EP2924132B1 (en) 2012-11-20 2020-05-06 JFE Steel Corporation Oxygen-gaseous fuel supply apparatus for sintering machine
CN103033063B (en) * 2012-12-28 2016-05-18 北京世纪源博科技股份有限公司 Sinter fume exhaust heat recovering method
JP7099700B2 (en) 2017-06-19 2022-07-12 ユニチカ株式会社 Bismaleimide modified product and its manufacturing method
US20230085232A1 (en) * 2020-02-27 2023-03-16 Jfe Steel Corporation Method for producing sintered ore
CN113215390B (en) * 2020-12-24 2022-07-22 北京高能时代环境技术股份有限公司 Copper-containing sludge sintering method

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0273924A (en) * 1988-09-09 1990-03-13 Nippon Steel Corp Oxygen-enriching operation in sintering machine
JPH0543951A (en) * 1991-08-13 1993-02-23 Nippon Steel Corp Method for operating sintering machine
EP0535727B1 (en) * 1991-10-03 1995-11-02 METALLGESELLSCHAFT Aktiengesellschaft Method for sintering iron oxide containing material on a sintering machine
JPH08100222A (en) * 1994-08-03 1996-04-16 Nippon Steel Corp Production of sintered ore

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103033064A (en) * 2012-12-28 2013-04-10 北京世纪源博科技股份有限公司 Device for recovering waste heat of sintering flue gas

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