JP2005053986A

JP2005053986A - Method for producing ferrocoke for blast furnace

Info

Publication number: JP2005053986A
Application number: JP2003206504A
Authority: JP
Inventors: Kenji Kato; 健次加藤; Masaaki Naito; 誠章内藤
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2003-08-07
Filing date: 2003-08-07
Publication date: 2005-03-03

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing high strength ferrocoke for blast furnaces, in which the powder of low grade coal (non-fine coking coal or the like) and biomass are used as a coke raw material. <P>SOLUTION: This method for producing the ferrocoke for the blast blasts, comprising mixing coal with an iron raw material, molding the mixture, and carbonizing the molded products, is characterized by (a) classifying powdered coal into dust coal and large particle coal, (b) mixing the dust coal with powdery iron raw material and biomass, (c) press-molding the mixture, and then (d) carbonizing only the molded products or a suitable mixture of the molded products with the large particle coal and/or the coking coal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、コークス原料として、低品質炭（非微粘結炭等）及びバイオマスを使用し、高炉用の高強度フェロコークスを製造する方法に関する。
【０００２】
【従来の技術】
高炉操業においては、従来から、粉状の粘結性炭や低粘結性炭を成形、乾留して製造した成形コークスが、室炉コークスに代替する還元材として用いられているが、コークスは、高炉内の通気性を確保するため所要の強度を備えている必要があり、成形コークスの強度向上を図る技術が、これまで数多く開示されている（例えば、特許文献１〜３、参照）。
【０００３】
特許文献１には、粘結性の少ない原料炭に、石炭系結合剤を添加して成型した塊成炭を、直立型乾留炉で、塊成炭の炉内滞留時間を制御しながら乾留する成形コークスの方法が開示されている。
【０００４】
また、特許文献２には、成形炭を固体熱媒（６００℃以上溶融温度以下に加熱された塊状又は塊成化した還元鉄又は酸化鉄）で直接加熱して乾留する成形コークスの製造方法が開示されている。
【０００５】
さらに、特許文献３には、非微粘結炭を所定量含有する粉炭にバインダーを添加して塊成化した成形炭を、竪型乾留炉で、羽口から吹き込む熱媒ガスの温度及び流量を調節しながら乾留する成形コークスの製造方法が開示されている。
【０００６】
このように、コークス用の高品質炭（強粘結炭）が枯渇傾向にあることを踏まえ、低品質炭（非微粘結炭）を使用する成形コークスの製造技術が開示されているが、低品質炭を原料とするが故、従来技術ではコークス強度の向上に限界があるのが実情である。
【０００７】
そこで、本発明者は、低品質粉炭の熱的特性に着目し、予熱後分級、分級微粉炭の急速加熱、急速加熱後の熱間成形、分級粗粒炭との混合乾留を基本工程とする高炉用コークスの製造方法を提案した（特許文献４、参照）。
【０００８】
特許文献４の方法は、原料炭の炭種拡大、生産性の向上等の点で効果の大きいものである。
【０００９】
また、高炉操業においては還元効率の向上が求められ、この観点から、鉄鉱石等の含鉄原料を含むフェロコークスが製造され使用されてきた（例えば、特許文献５〜８、参照）。
【００１０】
例えば、特許文献５には、石炭粉及び粉状鉄源に粘結材を加えて混練、加圧成型してブリケットを製造し、原料石炭粉と混合して乾留するフェロコークスの製造方法が開示されている。
【００１１】
また、特許文献６には、粉状鉄源と粉状石炭との混合成形物をシャフト炉に装入して成型フェロコークスを製造するに際し、シャフト炉の炉頂ガスをシャフト炉に供給する成型フェロコークスの製造方法が開示されている。
【００１２】
また、特許文献７には、溶融還元製鉄法において、粉状含鉄原料と粉状石炭の混合物からなる成形物を乾留して得た成形フェロコークスを用いることが開示されている。
【００１３】
さらに、特許文献８には、室式コークス炉に、石炭と粉状鉄源を一定の比率で装入して乾留し、一部被還元された粉状鉄源を内包するフェロコークスを製造する方法が開示されている。
【００１４】
しかし、高炉用フェロコークスにおいても、当然に、所要のコークス強度が求められ、コークス用の高品質炭（強粘結炭等）が枯渇傾向にある現在、低品質粉炭をコークス原料として使用し、高炉用の高強度フェロコークスを製造する技術の開発が求められている。
【００１５】
ところで、地球温暖化問題への対応策の一つとして、廃棄物エネルギーの利用が進められている。特に、バイオマスはカーボンニュートラルであり、石油・石炭に替わり積極的に使用されるべきエネルギー資源として注目されている。
【００１６】
バイオマスは、農業系（麦藁、サトウキビ、米糠、草木等）、林業系（製紙廃棄物、製材廃材、除間伐材、薪炭林等）、畜産系（家畜廃棄物）、水産系（水産加工残滓）、廃棄物系（生ゴミ、ゴミ固形化燃料、庭木、建設廃材、下水汚泥）等に分類されるが、廃棄物系バイオマスは、固定炭素と呼ばれる炭素分、即ち、無酸素雰囲気下の熱分解でガス化せず、固体炭素として残渣となる炭素分を含んでいる。
【００１７】
このバイオマス残渣（固定炭素）は、燃焼性、着火性に優れ、他の性状もコークスに比べ遜色がないので、コークスとして使用し得るものである。
【００１８】
しかし、固定炭素の特性に着目し、バイオマスをコークス原料として直接利用する技術は、今のところ提案されていない。
【００１９】
特許文献９には、廃棄物系バイオマスの一つの下水汚泥を、コークス乾式消火装置のプレチャンバー内に投入して焼却処理する方法が開示されているが、この方法では、固定炭素の多くは、ダストとして可燃ガスとともに煙道に導かれ、結局は、有効に利用されないまま飛散することになる。
【００２０】
このように、バイオマスに含まれる炭素分は、エネルギー資源としての有効性が認識されているにも拘わらず、これを有効に利用する技術は見あたらない。
【００２１】
【特許文献１】
特公昭６０−３８４３７号公報
【特許文献２】
特公昭６２−４５９１４号公報
【特許文献３】
特開平７−１４５３８５号公報
【特許文献４】
特開平８−２０９１５０号公報
【特許文献５】
特開昭６３−１３７９８９号公報
【特許文献６】
特開昭６４−８１８８９号公報
【特許文献７】
特開平４−２８８１０号公報
【特許文献８】
特開平１０−２８７８８３号公報
【特許文献９】
特開平６−２３３９９９号公報
【００２２】
【発明が解決しようとする課題】
本発明は、上記実情・現状に鑑み、コークス原料として、低品質炭（非粘結炭、微粘結炭等）の粉炭、及び、バイオマスを使用し、高炉用の高強度フェロコークスを製造することを目的とする。
【００２３】
【課題を解決するための手段】
本発明者は、鉄原料を含むフェロコークスの製造において、コークス原料として、非微粘結炭及びバイオマスを使用することを前提に、コークス強度の向上を図る非微粘結粉炭の処理、及び、バイオマス中の炭素分を非微粘結粉炭と一体的にコークス化するための製造工程について鋭意検討した。
【００２４】
その結果、（ｉ）非微粘結粉炭の熱的特性に立脚する一連の処理（予熱後分級、急速加熱、熱間成形）により、非微粘結微粉炭の粘結性が改善され、コークス強度が向上すること、及び、（ｉｉ）バイオマスを直接コークス原料に混合することが、粘結材としての機能も果たし、コークス強度の向上に有効であること、を知見した。
【００２５】
本発明は、上記知見に基づいてなされたもので、その要旨は、以下のとおりである。
【００２６】
（１）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭と粉状鉄原料を、さらに、バイオマスを加えて混合し、
（ｃ）上記混合物を加圧成形し、次いで、
（ｄ−１）上記成形物を単独で、又は、上記粗粒炭及び／又は粘結炭と適宜混合して乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００２７】
（２）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭と粉状鉄原料を、さらに、バイオマスを加えて混合し、
（ｃ）上記混合物を加圧成形し、次いで、
（ｄ−２）上記成形物を上記粗粒炭及び／又は粘結炭と適宜混合してブリケットに成形後、乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００２８】
（３）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を予熱して、微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭と粉状鉄原料を、さらに、バイオマスを加えて混合し、
（ｃ）上記混合物を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱して加圧成形し、次いで、
（ｄ−１）上記成形物を単独で、又は、上記粗粒炭及び／又は粘結炭と適宜混合して乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００２９】
（４）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を予熱して、微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭と粉状鉄原料を、さらに、バイオマスを加えて混合し、
（ｃ）上記混合物を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱して加圧成形し、次いで、
（ｄ−２）上記成形物を上記粗粒炭及び／又は粘結炭と適宜混合してブリケットに成形後、乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００３０】
（５）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を予熱して、微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱して、粉状鉄原料と、さらに、バイオマス加えて混合し、
（ｃ）上記混合物を加圧成形し、次いで、
（ｄ−１）上記成形物を単独で、又は、上記粗粒炭及び／又は粘結炭と適宜混合して乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００３１】
（６）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を予熱して、微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱して、粉状鉄原料と、さらにバイオマス加えて混合し、
（ｃ）上記混合物を加圧成形し、次いで、
（ｄ−２）上記成形物を上記粗粒炭及び／又は粘結炭と適宜混合してブリケットに成形後、乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００３２】
（７）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を予熱して、微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱して造粒し、
（ｃ）上記造粒物と粉状鉄原料を、さらに、バイオマスを加えて、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度で混合して加圧成形し、次いで、
（ｄ−１）上記成形物を単独で、又は、上記粗粒炭及び／又は粘結炭と適宜混合して乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００３３】
（８）石炭と鉄原料を混合、成形し、乾留して高炉用フェロコークスを製造する方法において、
（ａ）粉炭を予熱して、微粉炭と粗粒炭に分級し、
（ｂ）上記微粉炭を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱して造粒し、
（ｃ）上記造粒物と粉状鉄原料を、さらに、バイオマスを加えて、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度で混合して加圧成形し、次いで、
（ｄ−２）上記成形物を上記粗粒炭及び／又は粘結炭と適宜混合してブリケットに成形後、乾留する、ことを特徴とする高炉用フェロコークスの製造方法。
【００３４】
（９）前記石炭が、非微粘結炭であることを特徴とする前記（１）〜（８）のいずれかに記載の高炉用フェロコークスの製造方法。
【００３５】
（１０）前記粉炭を２５０〜３５０℃に予熱することを特徴とする前記（１）〜（８）のいずれかに記載の高炉用フェロコークスの製造方法。
【００３６】
（１１）前記微粉炭が、粒径０．３ｍｍ以下の微粉炭であることを特徴とする前記（１）〜（１０）のいずれかに記載の高炉用フェロコークスの製造方法。
【００３７】
（１２）前記粗粒炭が、粒径０．３ｍｍ超の粗粒炭であることを特徴とする前記（１）〜（１１）のいずれかに記載の高炉用フェロコークスの製造方法。
【００３８】
（１３）前記急速加熱を１×１０^２〜１×１０^５℃／分の加熱速度で行うことを特徴とする前記（１）〜（１２）のいずれかに記載の高炉用フェロコークスの製造方法。
【００３９】
（１４）前記粉状鉄原料を、微粉炭１００質量部に対し、５〜６０質量部混合することを特徴とする前記（１）〜（１３）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４０】
（１５）前記粉状鉄原料が、粒径０．０１〜１０ｍｍの鉄鉱石であることを特徴とする前記（１）〜（１４）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４１】
（１６）前記粉状鉄原料が、製鉄ダストを含むことを特徴とする前記（１）〜（１５）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４２】
（１７）前記バイオマスが、木質系バイオマス及び／又は廃棄物系バイオマスであることを特徴とする前記（１）〜（１６）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４３】
（１８）前記バイオマスを、微粉炭と粉状鉄原料１００質量部、又は、造粒炭と粉状鉄原料１００質量部に対し、１〜２０質量部混合することを特徴とする前記（１）〜（１７）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４４】
（１９）前記加圧成形を、５〜１，０００ｋｇ／ｃｍ^２の圧力で行うことを特徴とする前記（１）〜（１８）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４５】
（２０）前記造粒を、加圧成形機による成形で行うことを特徴とする前記（１）〜（１９）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４６】
（２１）前記成形物が、円相当径０．３ｍｍ以上の柱状物ないし棒状物であることを特徴とする前記（１）〜（２０）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４７】
（２２）前記造粒炭が、粒径０．３ｍｍ未満の球状成形物、又は、枕型成形物であることを特徴とする前記（１）〜（２１）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４８】
（２３）前記ブリケットが、最大径１２０〜１５０ｍｍのブリケットであることを特徴とする前記（２）、（４）、（６）、（８）、及び、（９）〜（２２）のいずれかに記載の高炉用フェロコークスの製造方法。
【００４９】
（２４）前記乾留を、室炉式コークス炉で行うことを特徴とする前記（１）、（３）、（５）、（７）、及び、（９）〜（２２）のいずれかに記載の高炉用フェロコークスの製造方法。
【００５０】
（２５）前記乾留を、縦型シャフト炉で行うことを特徴とする前記（２）、（４）、（６）、（８）、及び、（９）〜（２３）のいずれかに記載の高炉用フェロコークスの製造方法。
【００５１】
【発明の実施の形態】
本発明について、図面に基づいて詳細に説明する。図１に、本発明の実施態様を示す。
【００５２】
配合貯槽１から非微粘結粉炭Ａを切り出し、乾燥予熱機２で、好ましくは８０〜３５０℃に加熱して乾燥予熱する。この乾燥予熱は、非微粘結炭の粘性を改善する効果を有するが、後工程の分級に支障をきたさない程度に十分乾燥されていれば、省略してもよい。それ故、図１に示す実施態様において、この乾燥予熱は、必ずしも必須のものではない。
【００５３】
非微粘結粉炭を乾燥予熱する場合、上記粘性改善効果は、通常、８０℃以上で発現するが、一方、３５０℃を超えると、石炭の熱分解が始まり、石炭が変質することがあるので、乾燥予熱温度の上限は３５０℃が好ましい。
【００５４】
乾燥予熱した又はしない粉炭を、サイクロンのような分級機３で、微粉炭Ａ１と粗粒炭Ａ２に分級する。石炭は、銘柄や含水量により被粉砕性が異なり、粉砕後の粒度分布も異なるので、本発明で微粉炭として扱う粒径範囲は、特に限定されるものではない。
【００５５】
微粉炭と粗粒炭を区分する臨界粒径は、石炭の銘柄や含水量、さらに、所望のコークス強度に応じて適宜設定すればよい。通常、粒径０．３ｍｍ以下の石炭を微粉炭として扱っているので、本発明においても、粒径０．３ｍｍ以下の石炭を微粉炭として扱うのが好ましい。
【００５６】
次に、分級した微粉炭Ａ１と、配合貯槽４から切り出した粉状鉄原料Ｂ、さらに、バイオマス貯槽１６から抜き出したバイオマスＤを、混合機７で混合する。
【００５７】
この場合、微粉炭Ａ１は予熱された状態で混合機７へ送給されるので、粉状鉄原料ＢとバイオマスＤについても、微粉炭Ａ１の予熱状態程度まで加熱して、混合機７へ送給するのが好ましい。
【００５８】
粉状鉄原料の混合割合は、高炉用コークスとしての強度を安定的に確保し、かつ、炉内還元効率の一定の向上を確保する点で、微粉炭１００質量部に対し、５〜６０質量部が好ましい。
【００５９】
上記混合割合が５質量％未満であると、炉内還元効率の向上は期待できないし、一方、６０質量％を超えると、所望のコークス強度を安定的に確保することが難しくなる。
【００６０】
粉状鉄原料としては、主として粉状鉄鉱石を用いるが、基本的には、鉄及び鉄酸化物を所要量含有している粉状の物質であればよく、鉄鉱石以外では、製鉄ダスト等を用いることができる。
【００６１】
粉状鉄原料Ｂ、微粉炭Ａ１、及び、バイオマスＤを混合機７で混合する場合、均一に混合するため、粉状鉄原料の粒径を、微粉炭の粒径に対応して適宜設定する。例えば、粒径０．３ｍｍ以下の微粉炭と混合する場合、粉状鉄原料は、粒径０．０１〜１０ｍｍのものが好ましい。
【００６２】
バイオマスの混合割合は、混合物の粘結性を高め、高炉用コークスとしての強度を安定的に確保する点で、微粉炭１００質量部に対し、１〜２０質量部が好ましい。
【００６３】
上記混合割合が１質量部未満であると、混合物の粘結性の向上に寄与しないし、一方、２０質量部を超えると、適正な粘結性を維持できず、成形物の強度が低下する。
【００６４】
バイオマスは、主として、排出量の多い木質系バイオマス及び／又は廃棄物系バイオマスを用いるが、基本的には、固定炭素として残留する炭素を所定量含んでいればよく、この限りで、どのような種類のバイオマスでもよい。
【００６５】
微粉炭Ａ１、バイオマスＤ、及び、粉状鉄原料Ｂを混合機７で均一に混合した後、この混合物を加圧成形機９に送給し、コークス炉に装入した時、できるだけ嵩密度を高め得る形状の成形物に加圧成形する。
【００６６】
加圧成形においては、上記混合物を、５〜１，０００ｋｇ／ｃｍ^２の圧力で、円相当径０．３ｍｍ以上の柱状物ないし棒状物に成形することが好ましい。
【００６７】
加圧力が５ｋｇ／ｃｍ^２未満であると、成形時の圧力が小さ過ぎて、成形物の歩留りが低下し、一方、１，０００ｋｇ／ｃｍ^２を超えると、成形機で加圧成形する際に、成形物内に亀裂が入り割れてしまうことがある。
【００６８】
上記圧力範囲にある圧力で成形することにより、成形後のハンドリングが容易で、かつ、所要のコークス強度を安定的に確保できる成形物を、歩留りよく得ることができる。
【００６９】
成形物の形状は柱状ないし棒状が好ましい。成形物が柱状物ないし棒状物であれば、成形物を単独で、又は、粗粒炭及び／又は粘結炭と混合してコークス炉内に装入した場合でも、コークス原料の嵩密度を高めることができ、コークス強度の向上に貢献する。
【００７０】
加圧成形機９で成形した成形物は、コークス炉へ装入する前、一旦、配合貯槽１２に貯蔵してもよい。この時、分級機３で分級した粗粒炭Ａ２、及び／又は、配合貯槽５から切り出して乾燥予熱機６で乾燥予熱した粘結炭Ｃと混合して、配合貯槽１２に貯蔵してもよい。
【００７１】
本発明においては、加圧成形機９で成形した成形物を、単独で、又は、粗粒炭Ａ２及び／又は粘結炭Ｃと適宜混合して、乾留炉で乾留する。
【００７２】
コークス炉として、通常、室炉式コークス炉１３又は縦型シャフト炉１５を用いるが、本発明においては、所要の乾留を実施できればよいから、その限りで、他の形式の炉を用いてもよい。
【００７３】
乾留炉として室炉式コークス炉１３を用いる場合には、上記成形物、又は、該成形物と粗粒炭Ａ２及び／又は粘結炭Ｃとの混合物を配合貯槽１２から切り出して、室炉式コークス炉１３に装入する。
【００７４】
ただし、乾留炉として縦型シャフト炉１５を用いる場合には、配合貯槽１２から切り出した上記成形物と粗粒炭Ａ２及び／又は粘結炭Ｃとの混合物を、ブリケット成形機１４でブリケットに成形して、縦型シャフト炉１５に装入する。
【００７５】
このように、配合貯槽１２から切り出した混合物をブリケットに成形して乾留することにより、高強度の成形コークスを製造することができる。
【００７６】
ブリケットを乾留炉内で乾留する場合は、熱伝導によってブリケットの乾留が進行する。このため、ブリケットの径が大きすぎると、炉内でブリケットを乾留する際に、ブリケット内で熱応力が大きくなり、乾留過程でブリケットに亀裂が発生し、乾留後のコークスの強度が低下する。
【００７７】
そこで、乾留時に、ブリケット内での亀裂発生を抑制する点から、ブリケットの最大径は１２０〜１５０ｍｍが好ましい。
【００７８】
なお、乾留温度は、いずれの炉を用いる場合でも、通常の９５０〜１２００℃でよい。
【００７９】
成形物と粗粒炭及び／又は粘結炭との混合割合は、特に限定されるものではない。選択する炉や、所望のコークス強度を考慮して、適宜設定すればよい。
【００８０】
本発明によれば、このようにして、高炉用の高強度フェロコークスを、安定的に歩留りよく製造することができる。
【００８１】
図２に、本発明の別の実施態様を示す。なお、図２中、図１に示すものと同じものについては、図１中の数字、記号と同じ数字、記号で示した。
【００８２】
図２に示す実施態様は、
（ｉ）非微粘結粉炭Ａを、乾燥予熱機２で乾燥予熱する点、及び、
（ｉｉ）混合物を、加圧成形機９に送給する前、急速加熱機８で、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱する点、
で、図１に示す実施態様と相違する。
【００８３】
配合貯槽１から非微粘結粉炭Ａを切り出し、乾燥予熱機２で、好ましくは８０〜３５０℃に加熱して乾燥予熱する。図２に示す実施態様において、この乾燥予熱は、必須の処理であり、非微粘結粉炭の粘結性を改善し、高強度のフェロコークスを製造する処理工程における最初の工程として重要である。
【００８４】
加熱温度が８０℃未満であると乾燥予熱が充分でなく、また、後工程の急速加熱によっても、粘結性の改善に至らない場合がある。一方、加熱温度が３５０℃超であると、石炭からガスが発生し、石炭が変質するので、コークス強度が低下してしまう。
【００８５】
図２に示す実施態様においては、微粉炭Ａ１、バイオマスＤ、及び、粉状鉄原料Ｂを混合機７で均一に混合した後、この混合物を、急速加熱機８へ送給し、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度まで急速加熱する。
【００８６】
この急速加熱が、非微粘結微粉炭の粘結性を改善するうえで、乾燥予熱と相俟って重要な処理である。
【００８７】
加熱速度は１×１０^２〜１×１０^５℃／分が好ましい。加熱速度が１×１０^２℃／分未満であると、粘結性改善効果が充分に発現せず、この限りで、加熱速度は１×１０^３℃／分以上であればよいが、実現可能な加熱速度として、上限値を１×１０^５℃／分に設定した。
【００８８】
非微粘結粉炭の乾燥予熱に続き、微粉炭と粗粒炭に分級し、分級した微粉炭を、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱すれば、非微粘結微粉炭自体の粘結性が向上することは、本発明者が、既に、特許文献４で開示したことであるが、本発明は、非粘結性の粉状鉄原料を所要量含むフェロコークスの製造であるから、非微粘結微粉炭自体の粘結性を高めても、それがコークス強度の向上に直結しないことが予想される。
【００８９】
そこで、本発明者は、粒径０．３ｍｍ以下の微粉炭、粒径０．０１〜１０ｍｍの粉状鉄鉱石、及び、バイオマスを、混合割合を変えて混合し、成形、乾留し、該微粉炭の急速加熱温度とコークス強度の関係を調査した。
【００９０】
その結果、非粘結性の粉状鉄鉱石との混合状態においても、基本的には、非微粘結微粉炭自体の粘結性の向上が、コークス強度の向上をもたらすことが判明した。
【００９１】
“粉状鉄原料、微粉炭及びバイオマスの混合物”を急速加熱機８で上記温度に急速加熱した後、加圧成型機９に送給し、コークス炉に装入した時、できるだけ嵩密度を高め得る形状の成形物に加圧成形する。以後の処理は、図１に示す実施態様の場合と同じである。
【００９２】
本発明によれば、このようにして、高炉用の高強度フェロコークスを、安定的に歩留りよく製造することができる。
【００９３】
図３に、本発明の別の実施態様を示す。なお、図３中、図２に示すものと同じものについては、図２中の数字、記号と同じ数字、記号で示した。
【００９４】
図３に示す実施態様は、
（ｉ）微粉炭Ａ１だけを、急速加熱機８で、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に急速加熱する点、及び、
（ｉｉ）急速加熱後、微粉炭Ａ１、バイオマスＤ、及び、粉状鉄原料Ｂを混合機７で混合する点、
で、図２に示す実施態様と異なる。
【００９５】
なお、混合機７による混合に際しては、粉状鉄原料Ｂ及びバイオマスＤを、微粉炭Ａ１の温度に近い温度まで予熱することが、混合機７で均一な混合を図るうえで好ましい。
【００９６】
本発明者は、本発明において、上記（ｉ）及び（ｉｉ）の工程を採用する実施態様においても、高炉用の高強度フェロコークスを、安定的に歩留りよく製造できることを実験的に確認した。
【００９７】
図４に、本発明のさらに別の実施態様を示す。なお、図４中、図１〜３に示すものと同じものについては、図１〜３中の数字、記号と同じ数字、記号で示した。
【００９８】
図４に示す実施態様は、
（ｉ）微粉炭Ａ１を、急速加熱後、造粒機１０で造粒する点、及び、
（ｉｉ）造粒炭、バイオマスＤ、及び、粉状鉄原料Ｂを、混合加圧成形機１１で混合し、加圧成形する点、
で、図３に示す実施態様と異なる。
【００９９】
造粒炭は、造粒直後の粉状鉄原料、及び、バイオマスとの均一な混合を図るうえで、粒径０．３ｍｍ未満の球状又は枕型のものが好ましい。造粒機１０は、どのような種類の造粒機でもよいが、球状又は枕型に造粒し得る造粒機又は塊成機として、例えば、ダブルロールプレス型の成形機、又は、ロールコンパクターなどが好ましい。
【０１００】
上記（ｉｉ）の混合加圧成形は、造粒炭、バイオマスＤ、及び、粉状鉄原料Ｂを、２５０℃以上で、かつ、石炭の軟化開始温度以下の温度に加熱して行う。この加熱により、混合加圧成形機１１において、均一な混合をなし、円滑な加圧成形を行うことができる。
【０１０１】
本発明者は、上記（ｉ）及び（ｉｉ）の工程を採用する実施態様においても、高炉用の高強度フェロコークスを、安定的に歩留りよく製造できることを実験的に確認した。
【０１０２】
なお、本発明において、コークス強度とは、ＪＩＳＫ２１５１に従って、ドラム試験機でコークスサンプルに対して１５０回転の衝撃を与えた後に、１５ｍｍの篩の上に残存する割合で表わす指標（ＤＩ^１５０ _１５）で示す。
【０１０３】
【実施例】
次に、本発明の実施例について説明するが、実施例における条件は、本発明の実施可能性及び効果を実証するために採用した一条件例であり、本発明は、該条件例に限定されるものではない。
【０１０４】
本発明は、本発明の要旨を逸脱せず、本発明の目的を達成する限りにおいて、適宜、条件を設定し得るものである。
【０１０５】
（実施例１）
粉炭を８０℃に予熱して、粒径０．３ｍｍ以下の微粉炭と粒径０．３ｍｍ超の粗粒炭に分級した。上記微粉炭と、粒径０．０１〜１．０ｍｍの鉄鉱石、及び／又は、粒径０．０１〜０．５ｍｍの製鉄ダスト等の粉状鉄原料、及び、木質系バイオマスを、表１に示す割合で混合して、混合物（ａ）（微粉炭９０ｍａｓｓ％、鉄鉱石５ｍａｓｓ％、バイオマス５ｍａｓｓ％）、及び、混合物（ｂ）（微粉炭８０ｍａｓｓ％、鉄鉱石５ｍａｓｓ％、製鉄ダスト５ｍａｓｓ％、バイオマス５ｍａｓｓ％）を調製した。
【０１０６】
これらの混合物（ａ）及び混合物（ｂ）を、加熱速度１５０℃／分で３００℃（２５０℃以上で、かつ、石炭の軟化開始温度以下の温度）に急速加熱し、ダブルロールプレス型の成形機を用い、７００ｋｇ／ｃｍ^２の圧力で、直径１５ｍｍの柱状に加圧成形した。
【０１０７】
次いで、上記柱状成形物を単独で、又は、粒径０．３ｍｍ超の粗粒炭及び／又は粒径０．１〜５．０ｍｍの粘結炭と、表２に示す混合割合で適宜混合して室炉式コークス炉に装入し、１０５０〜１１００℃で乾留した。
【０１０８】
得られたフェロコークスの性状を表３に示す。表３から、得られたコークスのドラム強度（ＤＩ^１５０ _１５）は８２．５〜８３．５であり、高炉用コークスとして充分に使用し得るコークスが得られていることが解かる。
【０１０９】
【表１】

【０１１０】
【表２】

【０１１１】
【表３】

【０１１２】
（実施例２）
実施例１で得た成形物（混合物（ａ）及び混合物（ｂ）を、加熱速度１５０℃／分で３００℃（２５０℃以上で、かつ、石炭の軟化開始温度以下の温度）に急速加熱し、ダブルロールプレス型の成形機を用い、７００ｋｇ／ｃｍ^２の圧力で、直径１５ｍｍの柱状に加圧成形して得た成形物）と、粒径０．３ｍｍ超の粗粒炭及び／又は粒径０．０１〜５．０ｍｍの粘結炭を、表４に示す割合で混合してブリケットに成形した。
【０１１３】
このブリケットを縦型シャフト炉に装入して、１０００〜１１００℃で乾留した。
【０１１４】
得られたフェロコークスの性状を表５に示す。表５から、得られたコークスのドラム強度（ＤＩ^１５０ _１５）は８３．１〜８３．９と高く、高炉用コークスとして充分に使用し得るコークスが得られていることが解かる。
【０１１５】
【表４】

【０１１６】
【表５】

【０１１７】
【発明の効果】
本発明によれば、非微粘結炭及びバイオマスを用いて高強度のフェロコークスを、低コストで歩留りよく製造することができる。
【０１１８】
したがって、本発明は、高炉の安定操業、生産性の向上、さらに、バイオマスの有効利用に大きく貢献する。
【図面の簡単な説明】
【図１】本発明の実施態様を示す図である。
【図２】本発明の別の実施態様を示す図である。
【図３】本発明の別の実施態様を示す図である。
【図４】本発明のさらに別の実施態様を示す図である。
【符号の説明】
１、４、５、１２…配合貯槽
２、６…乾燥予熱機
３…分級機
７…混合機
８…急速加熱機
９…加圧成型機
１０…造粒機
１１…混合加圧成型機
１３…室炉式コークス炉
１４…ブリケット成形機
１５…縦型シャフト炉
１６…バイオマス貯槽
Ａ…非微粘結粉炭
Ａ１…微粉炭
Ａ２…粗粒炭
Ｂ…粉状鉄原料
Ｃ…粘結炭
Ｄ…バイオマス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing high-strength ferro-coke for a blast furnace using low-quality coal (non-slightly caking coal or the like) and biomass as coke raw materials.
[0002]
[Prior art]
In blast furnace operation, conventionally formed coke produced by molding and dry distillation of powdered caking coal or low caking coal has been used as a reducing material to replace chamber coke. In order to ensure air permeability in the blast furnace, it is necessary to have a required strength, and many techniques for improving the strength of the formed coke have been disclosed so far (see, for example, Patent Documents 1 to 3).
[0003]
In Patent Document 1, agglomerated coal obtained by adding a coal-based binder to coking coal with less caking property is subjected to carbonization in an upright type carbonization furnace while controlling the residence time of the agglomerated coal in the furnace. A method of forming coke is disclosed.
[0004]
Patent Document 2 discloses a method for producing formed coke, in which formed coal is directly heated with a solid heating medium (agglomerated or agglomerated reduced iron or iron oxide heated to a melting temperature of 600 ° C. or higher) and dry-distilled. It is disclosed.
[0005]
Furthermore, in Patent Document 3, the temperature and flow rate of the heat transfer medium gas blown from the tuyere in a vertical carbonization furnace is obtained by adding a binder to a coal powder containing a predetermined amount of non-slightly caking coal and agglomerating the coal. Disclosed is a method for producing molded coke that is carbonized while adjusting the temperature.
[0006]
Thus, based on the tendency of exhausting high-quality coal for coke (strongly caking coal), the production technology of molded coke using low-quality coal (non-caking coal) has been disclosed. Since low quality charcoal is used as a raw material, there is a limit to the improvement of coke strength in the prior art.
[0007]
Therefore, the present inventor pays attention to the thermal characteristics of low-quality pulverized coal, and the basic processes are classification after preheating, rapid heating of classified pulverized coal, hot forming after rapid heating, and mixed dry distillation with classified coarse coal. A method for producing coke for blast furnace was proposed (see Patent Document 4).
[0008]
The method of Patent Document 4 is highly effective in terms of expanding the coal type of the raw coal and improving productivity.
[0009]
Further, in blast furnace operation, improvement in reduction efficiency is required. From this viewpoint, ferro-coke containing iron-containing raw materials such as iron ore has been manufactured and used (see, for example, Patent Documents 5 to 8).
[0010]
For example, Patent Document 5 discloses a ferro-coke manufacturing method in which a caking additive is added to coal powder and powdered iron source, kneaded and pressure-molded to produce briquettes, mixed with raw material coal powder and dry-distilled. Has been.
[0011]
Further, in Patent Document 6, when a molded ferro-coke is produced by charging a mixed molded product of a powdered iron source and powdered coal into a shaft furnace, a mold for supplying the top gas of the shaft furnace to the shaft furnace. A method for producing ferro-coke is disclosed.
[0012]
Patent Document 7 discloses the use of molded ferro-coke obtained by dry distillation of a molded product composed of a mixture of powdered iron-containing raw material and powdered coal in a smelting reduction ironmaking process.
[0013]
Furthermore, in Patent Document 8, a ferro-coke containing a partly reduced powder iron source is manufactured by charging coal and a powder iron source in a certain ratio into a chamber coke oven and dry-distilling them. A method is disclosed.
[0014]
However, ferro-coke for blast furnaces is naturally required to have the required coke strength. Currently, high-quality coal for coke (strongly caking coal, etc.) tends to be exhausted, and low-quality pulverized coal is used as coke raw material. Development of technology for producing high-strength ferrocoke for blast furnaces is required.
[0015]
By the way, the use of waste energy is being promoted as one of the countermeasures against the global warming problem. In particular, biomass is carbon neutral and has attracted attention as an energy resource that should be actively used in place of oil and coal.
[0016]
Biomass is from agriculture (wheat straw, sugarcane, rice bran, vegetation, etc.), forestry (papermaking waste, sawn timber, thinned wood, firewood charcoal forest, etc.), livestock (livestock waste), aquaculture (residue from fishery processing) , Waste biomass (garbage, garbage solidified fuel, garden trees, construction waste, sewage sludge), etc., but waste biomass is a carbon component called fixed carbon, that is, thermal decomposition in an oxygen-free atmosphere It contains no carbon that becomes a residue as solid carbon.
[0017]
This biomass residue (fixed carbon) is excellent in combustibility and ignitability, and other properties are not inferior to coke, and can be used as coke.
[0018]
However, no technology has been proposed so far that focuses on the characteristics of fixed carbon and uses biomass directly as coke feedstock.
[0019]
Patent Document 9 discloses a method of injecting one sewage sludge of waste biomass into a pre-chamber of a coke dry fire extinguisher and incinerating it. In this method, most of fixed carbon is It will be led to the flue with combustible gas as dust and will eventually be scattered without being used effectively.
[0020]
Thus, although the carbon content contained in the biomass is recognized as being effective as an energy resource, there is no technology for effectively using it.
[0021]
[Patent Document 1]
Japanese Patent Publication No. 60-38437
[Patent Document 2]
Japanese Examined Patent Publication No. 62-45914
[Patent Document 3]
JP 7-145385 A
[Patent Document 4]
JP-A-8-209150
[Patent Document 5]
Japanese Unexamined Patent Publication No. 63-137989
[Patent Document 6]
Japanese Unexamined Patent Publication No. 64-81889
[Patent Document 7]
JP-A-4-28810
[Patent Document 8]
Japanese Patent Laid-Open No. 10-287883
[Patent Document 9]
JP-A-6-233999
[0022]
[Problems to be solved by the invention]
In view of the above circumstances and the present situation, the present invention produces high-strength ferro-coke for blast furnaces by using pulverized coal of low quality coal (non-caking coal, slightly caking coal, etc.) and biomass as coke raw materials. For the purpose.
[0023]
[Means for Solving the Problems]
The present inventor, in the production of ferro-coke containing iron raw material, on the premise that non-slightly caking coal and biomass are used as a coke raw material, treatment of non-slightly caking coal, which aims to improve coke strength, and The production process for coking the carbon content of biomass with the non-sintered coal was investigated.
[0024]
As a result, (i) a series of treatments (classification after preheating, rapid heating, hot forming) based on the thermal characteristics of non-slightly caking coal improves the caking of non-slightly caking coal, and coke. It has been found that the strength is improved and that (ii) mixing biomass directly with the coke raw material also serves as a caking additive and is effective in improving the coke strength.
[0025]
This invention was made | formed based on the said knowledge, The summary is as follows.
[0026]
(1) In a method for producing ferro-coke for blast furnace by mixing, forming and dry-distilling coal and iron raw materials,
(A) Classifying pulverized coal into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) pressing the mixture and then
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.
[0027]
(2) In a method for producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Classifying pulverized coal into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) pressing the mixture and then
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, molded into briquettes, and then dry-distilled.
[0028]
(3) In a method for producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) The above mixture is rapidly heated to a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal, and then press-molded.
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.
[0029]
(4) In a method for producing ferro-coke for blast furnace by mixing, molding and dry-distilling coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) The above mixture is rapidly heated to a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal, and then press-molded.
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.
[0030]
(5) In a method for producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is rapidly heated to a temperature equal to or higher than 250 ° C. and equal to or lower than the softening start temperature of the coal.
(C) pressing the mixture and then
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.
[0031]
(6) In a method for producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is rapidly heated to a temperature not lower than 250 ° C. and not higher than the softening start temperature of the coal, and the powdered iron raw material is further added to the biomass and mixed.
(C) pressing the mixture and then
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.
[0032]
(7) In a method for producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is granulated by rapid heating to a temperature of 250 ° C or higher and lower than the softening start temperature of the coal,
(C) The above granulated product and powdered iron raw material are further added with biomass, mixed at a temperature of 250 ° C. or higher and lower than the softening start temperature of coal, and then press-molded.
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.
[0033]
(8) In a method for producing ferro-coke for blast furnace by mixing, forming and dry-distilling coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is granulated by rapid heating to a temperature of 250 ° C or higher and lower than the softening start temperature of the coal,
(C) The above granulated product and powdered iron raw material are further added with biomass, mixed at a temperature of 250 ° C. or higher and lower than the softening start temperature of coal, and then press-molded.
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.
[0034]
(9) The method for producing ferro-coke for blast furnace according to any one of (1) to (8), wherein the coal is non-coking coal.
[0035]
(10) The method for producing ferro-coke for blast furnace according to any one of (1) to (8), wherein the pulverized coal is preheated to 250 to 350 ° C.
[0036]
(11) The method for producing ferro-coke for blast furnace according to any one of (1) to (10), wherein the pulverized coal is pulverized coal having a particle size of 0.3 mm or less.
[0037]
(12) The method for producing ferro-coke for blast furnace according to any one of (1) to (11), wherein the coarse coal is coarse coal having a particle size of more than 0.3 mm.
[0038]
(13) The rapid heating is performed at 1 × 10²~ 1x10⁵The method for producing ferro-coke for blast furnace according to any one of (1) to (12), wherein the method is performed at a heating rate of ° C / min.
[0039]
(14) The ferro-coke for blast furnace according to any one of (1) to (13), wherein the powdered iron raw material is mixed in an amount of 5 to 60 parts by mass with respect to 100 parts by mass of pulverized coal. Method.
[0040]
(15) The method for producing ferrocoke for blast furnace according to any one of (1) to (14), wherein the powdered iron raw material is iron ore having a particle diameter of 0.01 to 10 mm.
[0041]
(16) The method for producing ferro-coke for blast furnace according to any one of (1) to (15), wherein the powdered iron raw material includes iron-making dust.
[0042]
(17) The method for producing ferro-coke for blast furnace according to any one of (1) to (16), wherein the biomass is woody biomass and / or waste biomass.
[0043]
(18) The biomass is mixed with 1 to 20 parts by mass with respect to 100 parts by mass of pulverized coal and powdered iron raw material or 100 parts by mass of granulated coal and powdered iron raw material (1) The manufacturing method of the ferro-coke for blast furnaces in any one of-(17).
[0044]
(19) The pressure molding is performed at 5 to 1,000 kg / cm.²The method for producing ferro-coke for blast furnace according to any one of the above (1) to (18), wherein the method is performed at a pressure of
[0045]
(20) The method for producing ferro-coke for blast furnace according to any one of (1) to (19), wherein the granulation is performed by molding with a pressure molding machine.
[0046]
(21) The method for producing ferro-coke for blast furnace according to any one of (1) to (20), wherein the molded product is a columnar or rod-shaped object having an equivalent circle diameter of 0.3 mm or more.
[0047]
(22) Blast furnace ferro as described in any one of (1) to (21) above, wherein the granulated coal is a spherical molded product having a particle size of less than 0.3 mm or a pillow molded product. Coke production method.
[0048]
(23) Any of (2), (4), (6), (8), and (9) to (22), wherein the briquette is a briquette having a maximum diameter of 120 to 150 mm. The manufacturing method of the ferro-coke for blast furnaces as described in 1 ..
[0049]
(24) The dry distillation is performed in a chamber-type coke oven, (1), (3), (5), (7), and any one of (9) to (22) Of manufacturing ferro-coke for blast furnace.
[0050]
(25) The dry distillation is performed in a vertical shaft furnace, (2), (4), (6), (8), and any one of (9) to (23) Manufacturing method of ferro-coke for blast furnace.
[0051]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention.
[0052]
The non-sintered caking coal A is cut out from the blending storage tank 1 and dried and preheated by the drying preheater 2, preferably at 80 to 350 ° C. This drying preheating has the effect of improving the viscosity of the non-slightly caking coal, but may be omitted if it is sufficiently dried to the extent that it does not hinder classification in the subsequent steps. Therefore, in the embodiment shown in FIG. 1, this drying preheating is not necessarily essential.
[0053]
In the case of drying and preheating non-sintered coal powder, the above-mentioned viscosity improving effect is usually manifested at 80 ° C. or higher. On the other hand, when it exceeds 350 ° C., coal pyrolysis starts and the coal may be altered. The upper limit of the drying preheating temperature is preferably 350 ° C.
[0054]
The dry and preheated pulverized coal is classified into pulverized coal A1 and coarse coal A2 by a classifier 3 such as a cyclone. Coal has different pulverization properties depending on the brand and water content, and the particle size distribution after pulverization also varies. Therefore, the particle size range handled as pulverized coal in the present invention is not particularly limited.
[0055]
What is necessary is just to set the critical particle size which classifies pulverized coal and coarse-grained coal suitably according to the brand and water content of coal, and also desired coke strength. Normally, coal having a particle size of 0.3 mm or less is handled as pulverized coal, and therefore, in the present invention, it is preferable to treat coal having a particle size of 0.3 mm or less as pulverized coal.
[0056]
Next, the classified pulverized coal A1, the powdered iron raw material B cut out from the blending storage tank 4, and the biomass D extracted from the biomass storage tank 16 are mixed by the mixer 7.
[0057]
In this case, since the pulverized coal A1 is fed to the mixer 7 in a preheated state, the pulverized iron raw material B and the biomass D are also heated to the preheated state of the pulverized coal A1 and fed to the mixer 7. It is preferable to supply.
[0058]
The mixing ratio of the powdered iron raw material is 5 to 60 masses with respect to 100 parts by mass of pulverized coal in terms of stably securing the strength as coke for blast furnace and ensuring a certain improvement in the reduction efficiency in the furnace. Part is preferred.
[0059]
If the mixing ratio is less than 5% by mass, the reduction efficiency in the furnace cannot be expected. On the other hand, if it exceeds 60% by mass, it is difficult to stably secure a desired coke strength.
[0060]
As powdered iron raw material, powdered iron ore is mainly used, but basically, any powdery substance containing a required amount of iron and iron oxide may be used. Can be used.
[0061]
When mixing the powdered iron raw material B, the pulverized coal A1, and the biomass D with the mixer 7, in order to mix uniformly, the particle size of the powdered iron raw material is appropriately set corresponding to the particle size of the pulverized coal. . For example, when mixing with pulverized coal having a particle size of 0.3 mm or less, the powdered iron material preferably has a particle size of 0.01 to 10 mm.
[0062]
The mixing ratio of the biomass is preferably 1 to 20 parts by mass with respect to 100 parts by mass of pulverized coal in terms of enhancing the caking property of the mixture and stably securing the strength as coke for blast furnace.
[0063]
When the mixing ratio is less than 1 part by mass, it does not contribute to the improvement of the caking property of the mixture. On the other hand, when it exceeds 20 parts by mass, the proper caking property cannot be maintained and the strength of the molded product is reduced. .
[0064]
Biomass mainly uses woody biomass and / or waste biomass with a large amount of emissions. Basically, it only needs to contain a predetermined amount of carbon that remains as fixed carbon. Different types of biomass may be used.
[0065]
After the pulverized coal A1, biomass D, and powdered iron raw material B are uniformly mixed in the mixer 7, the mixture is fed to the pressure molding machine 9 and charged to the coke oven to obtain the bulk density as much as possible. Press-molded into a shape that can be enhanced.
[0066]
In pressure molding, the above mixture is 5 to 1,000 kg / cm.²It is preferable to form into a columnar or rod-shaped object having a circle-equivalent diameter of 0.3 mm or more at a pressure of 1 mm.
[0067]
Applied pressure is 5 kg / cm²If it is less than 1, the pressure at the time of molding is too small, and the yield of the molded product is lowered, while 1,000 kg / cm²If it exceeds 1, cracks may occur in the molded product when it is pressure-molded by a molding machine.
[0068]
By molding at a pressure within the above pressure range, a molded product that can be easily handled after molding and can stably secure a required coke strength can be obtained with high yield.
[0069]
The shape of the molded product is preferably a columnar shape or a rod shape. If the molded product is a columnar product or a rod-shaped product, the bulk density of the coke raw material is increased even when the molded product is used alone or mixed with coarse coal and / or caking coal and charged in a coke oven. Can contribute to the improvement of coke strength.
[0070]
The molded product molded by the pressure molding machine 9 may be temporarily stored in the compounding storage tank 12 before being charged into the coke oven. At this time, the coarse coal A2 classified by the classifier 3 and / or the caking coal C cut out from the blended storage tank 5 and dried and preheated by the dry preheater 6 may be mixed and stored in the blended storage tank 12. .
[0071]
In the present invention, the molded product formed by the pressure molding machine 9 is singly or appropriately mixed with coarse coal A2 and / or caking coal C, and subjected to dry distillation in a dry distillation furnace.
[0072]
As the coke oven, a chamber-type coke oven 13 or a vertical shaft furnace 15 is usually used. However, in the present invention, it is only necessary to carry out a required dry distillation, so that other types of ovens may be used. .
[0073]
When using a furnace type coke oven 13 as a dry distillation furnace, the above molded product or a mixture of the molded product and coarse coal A2 and / or caking coal C is cut out from the blending storage tank 12, and the chamber type The coke oven 13 is charged.
[0074]
However, when the vertical shaft furnace 15 is used as a dry distillation furnace, a mixture of the molded product cut out from the blending storage tank 12 and the coarse coal A2 and / or caking coal C is formed into briquettes by the briquette molding machine 14. Then, it is charged into the vertical shaft furnace 15.
[0075]
Thus, a high-strength molded coke can be manufactured by shape | molding the mixture cut out from the mixing | blending storage tank 12 to a briquette, and carrying out dry distillation.
[0076]
When briquetting is performed in a carbonization furnace, the briquetting of the briquettes proceeds by heat conduction. For this reason, if the diameter of the briquette is too large, when the briquette is carbonized in the furnace, the thermal stress increases in the briquette, cracks are generated in the briquette process, and the strength of the coke after the carbonization is lowered.
[0077]
Therefore, the maximum diameter of the briquette is preferably 120 to 150 mm from the viewpoint of suppressing the occurrence of cracks in the briquette during dry distillation.
[0078]
The dry distillation temperature may be a normal 950 to 1200 ° C., regardless of which furnace is used.
[0079]
The mixing ratio of the molded product and coarse coal and / or caking coal is not particularly limited. What is necessary is just to set suitably in consideration of the furnace to select and desired coke intensity | strength.
[0080]
According to the present invention, high-strength ferrocoke for blast furnaces can be produced stably and with high yield in this way.
[0081]
FIG. 2 shows another embodiment of the present invention. 2 that are the same as those shown in FIG. 1 are indicated by the same numbers and symbols as those shown in FIG.
[0082]
The embodiment shown in FIG.
(I) The non-slightly caking coal A is dried and preheated by the drying preheater 2, and
(Ii) Before the mixture is fed to the pressure molding machine 9, the rapid heating machine 8 rapidly heats the mixture to a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal,
Thus, it is different from the embodiment shown in FIG.
[0083]
The non-sintered caking coal A is cut out from the blending storage tank 1 and dried and preheated by the drying preheater 2, preferably at 80 to 350 ° C. In the embodiment shown in FIG. 2, this drying preheating is an essential process and is important as the first step in the process of improving the caking of non-fine caking coal and producing high strength ferrocoke. .
[0084]
If the heating temperature is less than 80 ° C., drying preheating is not sufficient, and the caking property may not be improved even by rapid heating in the subsequent step. On the other hand, when the heating temperature is higher than 350 ° C., gas is generated from the coal and the coal is deteriorated, so that the coke strength is lowered.
[0085]
In the embodiment shown in FIG. 2, after the pulverized coal A1, biomass D, and powdered iron raw material B are uniformly mixed in the mixer 7, this mixture is fed to the rapid heating machine 8 and 250 ° C. or higher. And rapid heating to a temperature below the coal softening start temperature.
[0086]
This rapid heating is an important treatment in combination with drying preheating in order to improve the caking property of non-minor caking pulverized coal.
[0087]
Heating rate is 1 × 10²~ 1x10⁵C / min is preferred. Heating rate is 1 × 10²When the temperature is less than ° C./minute, the caking improvement effect is not sufficiently exhibited.³The upper limit is set to 1 × 10 as a feasible heating rate.⁵Set to ° C / min.
[0088]
Subsequent to drying preheating of non-finely caking coal, it is classified into pulverized coal and coarse coal, and if the classified pulverized coal is rapidly heated to a temperature of 250 ° C or higher and below the softening start temperature of coal, The fact that the caking property of the caking pulverized coal itself is improved is that the inventor has already disclosed it in Patent Document 4, but the present invention includes a required amount of non-caking powdered iron raw material. Since it is a production of ferro-coke, it is expected that even if the caking property of non-minor caking pulverized coal itself is increased, it does not directly lead to an improvement in coke strength.
[0089]
Therefore, the present inventor mixed pulverized coal with a particle size of 0.3 mm or less, pulverized iron ore with a particle size of 0.01 to 10 mm, and biomass at different mixing ratios, molding, dry distillation, The relationship between the rapid heating temperature of coal and coke strength was investigated.
[0090]
As a result, it has been found that even in a mixed state with non-caking pulverized iron ore, basically, an improvement in caking property of non-caking pulverized coal itself leads to an improvement in coke strength.
[0091]
After rapidly heating the “mixture of powdered iron raw material, pulverized coal and biomass” to the above temperature with the rapid heating machine 8, the bulk density is increased as much as possible when fed to the pressure molding machine 9 and charged into the coke oven. Press-molded into a shaped product. The subsequent processing is the same as in the embodiment shown in FIG.
[0092]
According to the present invention, high-strength ferrocoke for blast furnaces can be produced stably and with high yield in this way.
[0093]
FIG. 3 shows another embodiment of the present invention. 3 that are the same as those shown in FIG. 2 are indicated by the same numbers and symbols as those shown in FIG.
[0094]
The embodiment shown in FIG.
(I) The point where only pulverized coal A1 is rapidly heated by the rapid heating machine 8 to a temperature of 250 ° C. or more and not more than the softening start temperature of coal, and
(Ii) The point which mixes pulverized coal A1, biomass D, and powdered iron raw material B with the mixer 7 after rapid heating,
This is different from the embodiment shown in FIG.
[0095]
In mixing with the mixer 7, it is preferable to preheat the powdered iron raw material B and the biomass D to a temperature close to the temperature of the pulverized coal A <b> 1 in order to achieve uniform mixing with the mixer 7.
[0096]
The inventor of the present invention experimentally confirmed that high strength ferro-coke for blast furnace can be produced stably and with high yield even in the embodiment employing the steps (i) and (ii).
[0097]
FIG. 4 shows still another embodiment of the present invention. In FIG. 4, the same components as those shown in FIGS. 1 to 3 are indicated by the same numerals and symbols as those shown in FIGS.
[0098]
The embodiment shown in FIG.
(I) The point which granulates pulverized coal A1 with the granulator 10 after rapid heating, and
(Ii) Granulated charcoal, biomass D, and powdered iron raw material B are mixed in a mixed pressure molding machine 11 and pressure molded.
This is different from the embodiment shown in FIG.
[0099]
The granulated coal is preferably a spherical or pillow type having a particle size of less than 0.3 mm in order to achieve uniform mixing with the powdered iron raw material immediately after granulation and biomass. The granulator 10 may be any type of granulator, but as a granulator or agglomerator capable of granulating into a spherical or pillow shape, for example, a double roll press type molding machine or a roll compactor. Etc. are preferable.
[0100]
The mixed pressure molding of (ii) is performed by heating the granulated coal, biomass D, and powdered iron raw material B to a temperature of 250 ° C. or higher and lower than the softening start temperature of the coal. By this heating, the mixed pressure molding machine 11 can perform uniform pressure mixing and smooth pressure molding.
[0101]
The present inventor has experimentally confirmed that high-strength ferrocoke for blast furnaces can be stably produced with good yield even in the embodiment employing the steps (i) and (ii).
[0102]
In the present invention, the coke strength is an index (DI expressed as a ratio remaining on a 15 mm sieve after an impact of 150 revolutions is applied to a coke sample with a drum tester in accordance with JIS K 2151.¹⁵⁰ ₁₅).
[0103]
【Example】
Next, examples of the present invention will be described. The conditions in the examples are one example of conditions adopted for demonstrating the feasibility and effects of the present invention, and the present invention is limited to the examples of conditions. It is not something.
[0104]
The present invention can appropriately set conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
[0105]
(Example 1)
The pulverized coal was preheated to 80 ° C. and classified into pulverized coal having a particle size of 0.3 mm or less and coarse coal having a particle size of more than 0.3 mm. Table 1 shows pulverized coal, iron ore having a particle diameter of 0.01 to 1.0 mm, and / or powdered iron raw materials such as iron-making dust having a particle diameter of 0.01 to 0.5 mm, and woody biomass. The mixture (a) (90% by mass of pulverized coal, 5% by mass of iron ore, 5% by mass of biomass) and the mixture (b) (80% by mass of pulverized coal, 5% by mass of iron ore, 5% by mass of iron making dust, Biomass 5 mass%) was prepared.
[0106]
These mixtures (a) and (b) are rapidly heated to 300 ° C. (a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal) at a heating rate of 150 ° C./min to form a double roll press mold. 700kg / cm using a machine²Was pressed into a columnar shape having a diameter of 15 mm.
[0107]
Next, the above columnar molded product is mixed as appropriate alone or with coarse coal having a particle size of more than 0.3 mm and / or caking coal having a particle size of 0.1 to 5.0 mm in a mixing ratio shown in Table 2. Was charged into a chamber-type coke oven and subjected to dry distillation at 1050 to 1100 ° C.
[0108]
Table 3 shows the properties of the obtained ferrocoke. From Table 3, the drum strength of the obtained coke (DI¹⁵⁰ ₁₅) Is 82.5 to 83.5, and it is understood that coke that can be sufficiently used as blast furnace coke is obtained.
[0109]
[Table 1]

[0110]
[Table 2]

[0111]
[Table 3]

[0112]
(Example 2)
The molded product obtained in Example 1 (mixture (a) and mixture (b) was rapidly heated to 300 ° C. (a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal) at a heating rate of 150 ° C./min). 700kg / cm using a double roll press type molding machine²A molded product obtained by pressure-molding into a columnar shape having a diameter of 15 mm), coarse coal having a particle size of more than 0.3 mm, and / or caking coal having a particle size of 0.01 to 5.0 mm, 4 were mixed at a ratio shown in FIG.
[0113]
This briquette was charged into a vertical shaft furnace and subjected to dry distillation at 1000 to 1100 ° C.
[0114]
Table 5 shows the properties of the obtained ferrocoke. From Table 5, the drum strength of the obtained coke (DI¹⁵⁰ ₁₅) Is as high as 83.1 to 83.9, and it is understood that coke that can be sufficiently used as coke for blast furnace is obtained.
[0115]
[Table 4]

[0116]
[Table 5]

[0117]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, a high intensity | strength ferro coke can be manufactured with low yield and a sufficient yield using non-slightly caking coal and biomass.
[0118]
Therefore, the present invention greatly contributes to stable operation of the blast furnace, improvement of productivity, and effective use of biomass.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 shows another embodiment of the present invention.
FIG. 3 shows another embodiment of the present invention.
FIG. 4 is a view showing still another embodiment of the present invention.
[Explanation of symbols]
1, 4, 5, 12, ... storage tank
2, 6 ... Drying preheater
3 ... Classifier
7 ... Mixer
8 ... Rapid heating machine
9 ... Pressure molding machine
10 ... Granulator
11 ... Mixed pressure molding machine
13 ... Chamber type coke oven
14 ... Briquetting machine
15 ... Vertical shaft furnace
16 ... Biomass storage tank
A ... Non-sintered coal
A1 ... pulverized coal
A2 ... Coarse coal
B ... Powdered iron raw material
C ... caking coal
D ... Biomass

Claims

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Classifying pulverized coal into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) pressing the mixture and then
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Classifying pulverized coal into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) pressing the mixture and then
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) The above mixture is rapidly heated to a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal, and then press-molded.
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal and powdered iron raw material are further mixed with biomass,
(C) The above mixture is rapidly heated to a temperature not lower than 250 ° C. and not higher than the softening start temperature of coal, and then press-molded.
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is rapidly heated to a temperature equal to or higher than 250 ° C. and equal to or lower than the softening start temperature of the coal.
(C) pressing the mixture and then
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is rapidly heated to a temperature equal to or higher than 250 ° C. and equal to or lower than the softening start temperature of the coal.
(C) pressing the mixture and then
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is granulated by rapid heating to a temperature of 250 ° C. or higher and lower than the softening start temperature of the coal,
(C) The above granulated product and powdered iron raw material are further added with biomass, mixed at a temperature of 250 ° C. or higher and lower than the softening start temperature of coal, and then press-molded.
(D-1) A method for producing ferro-coke for blast furnace, characterized in that the above molded product is dry-distilled alone or appropriately mixed with the coarse coal and / or caking coal.

In the method of producing ferro-coke for blast furnace by mixing, molding and dry distillation of coal and iron raw materials,
(A) Preheating the pulverized coal, classifying it into pulverized coal and coarse coal,
(B) The above pulverized coal is granulated by rapid heating to a temperature of 250 ° C. or higher and lower than the softening start temperature of the coal,
(C) The above granulated product and powdered iron raw material are further added with biomass, mixed at a temperature of 250 ° C. or higher and lower than the softening start temperature of coal, and then press-molded.
(D-2) A method for producing ferro-coke for blast furnace, characterized in that the molded product is appropriately mixed with the coarse coal and / or caking coal, formed into a briquette, and then dry-distilled.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 8, wherein the coal is non-coking coal.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 8, wherein the pulverized coal is preheated to 250 to 350 ° C.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 10, wherein the pulverized coal is pulverized coal having a particle size of 0.3 mm or less.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 11, wherein the coarse coal is coarse coal having a particle diameter of more than 0.3 mm.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 12, wherein the rapid heating is performed at a heating rate of 1 x 10 ² to 1 x 10 ⁵ ° C / min.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 13, wherein the powdered iron raw material is mixed in an amount of 5 to 60 parts by mass with respect to 100 parts by mass of pulverized coal.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 14, wherein the powdered iron raw material is iron ore having a particle diameter of 0.01 to 10 mm.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 15, wherein the powdered iron raw material contains iron-making dust.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 16, wherein the biomass is woody biomass and / or waste biomass.

The biomass is mixed in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of pulverized coal and 100 parts by mass of powdered iron raw material, or 100 parts by mass of granulated coal and powdered iron raw material. The manufacturing method of the ferro-coke for blast furnaces of Claim 1.

The method of manufacturing blast furnace ferro coke according to any one of claims 1 to 18 wherein the pressure molding, and performing at a pressure of 5~1,000kg / cm ^2.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 19, wherein the granulation is performed by molding with a pressure molding machine.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 20, wherein the molded product is a columnar or rod-shaped object having an equivalent circle diameter of 0.3 mm or more.

The method for producing ferro-coke for blast furnace according to any one of claims 1 to 21, wherein the granulated coal is a spherical molded product having a particle size of less than 0.3 mm or a pillow-shaped molded product. .

The method for producing ferro-coke for blast furnace according to any one of claims 2, 4, 6, 8, and 9 to 22, wherein the briquette is a briquette having a maximum diameter of 120 to 150 mm.

The method for producing ferro-coke for blast furnace according to any one of claims 1, 3, 5, 7, and 9 to 22, wherein the dry distillation is performed in a chamber-type coke oven.

The method for producing ferro-coke for blast furnace according to any one of claims 2, 4, 6, 8, and 9 to 23, wherein the dry distillation is performed in a vertical shaft furnace.