JP4537632B2 - Carbonaceous refractory and method for producing the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、非酸化雰囲気で使用される耐火物、特に高炉湯溜まりの側壁部と炉底部の内張り材に適する炭素質耐火物及びその製造方法に関する。
【０００２】
【従来の技術】
近年の非酸化雰囲気の窯炉、例えば高炉は、大型化が進むと共に操業は過酷化し、高圧操業、微粉炭吹き込み操業等により、内張り耐火物が損傷する要因が増加している反面、高炉の高額な初期投資を抑制するために長寿命化が望まれている。このような高炉の寿命の律速は、高炉湯溜まりの側壁部と炉底部の内張り材の耐久性である。この高炉湯溜まりの側壁部と炉底部の部位の内張り材としては、炭素質耐火物が使用されている。すなわち、内張り材として用いられる炭素質耐火物の耐久性の向上が、高炉の延命に直接的な効果をもたらす。
【０００３】
炭素質耐火物は、一般に、焙焼無煙炭、人造黒鉛、天然黒鉛等の炭素骨材に、コールタールピッチ、フェノール樹脂等の有機バインダーを加えて混練し、押し出し成形または型込め成形した後、コークスブリーズ中に埋没して焼成することにより製造される。また、炭素質耐火物は、粘土質れんがに比べて、炭素骨材の溶銑への加炭溶解による侵食が生じるという短所を有しているが、熱伝導性が高く、また耐スラグ性にも優れていることから、古くから高炉湯溜まり部の内張り材に使用されている。
【０００４】
また、高炉内での内張り炭素質耐火物の損傷の原因としては、溶銑への加炭溶解、気孔中への溶銑の侵入が原因となって生じる破壊、アルカリや亜鉛蒸気の侵入と反応による亀裂の生成、熱応力による破壊、溶銑流動による摩耗等が挙げられる。
【０００５】
このため、従来から炭素質耐火物の耐久性の向上を図ることを目的として、炭素質耐火物の配合、製造方法、使用方法等について多くの提案がなされ、実施されてきた。本出願人においても、溶銑への加炭溶解速度を小さくするために、特公昭５６−１８５５９号公報には、主原料の炭素骨材に加えて、α−アルミナ、ジルコン、マグネシア等の金属酸化物を含有させた高炉用炭素質耐火物を開示した。
【０００６】
また、特公昭５８−４３３５０号公報には、炭素骨材を主原料として、金属珪素微粉を配合し、焼成過程で炭素質耐火物の気孔内にひげ状の珪素化合物を生成させて、溶銑が侵入できる直径１μｍ以上の気孔を少なくし、溶銑や反応性ガスの炭素質耐火物への侵入を減少させる高炉用炭素質耐火物の製造方法を開示した。
【０００７】
さらに、特開平８−８１７０６号公報には、熱伝導性を高めるため、熱伝導率の大きい人造黒鉛、天然黒鉛等の炭素骨材を主原料とする場合において、加炭溶解速度が小さく、且つ、気孔径の小さい大型炭素質耐火物を安定して製造できる高炉用炭素質耐火物の製造方法を開示した。
【０００８】
また、特開平６−４８８２０号公報には、鋼の製造工程において使用される炭素含有耐火材において，Ｔａ，Ｎｂ又はそれらの炭化物を添加する発明が開示され、特開平７−２５７９８１号公報には、炭素含有耐火物を接合する場合、高い接合強度を得るために、Ｎｂ，Ｖ，Ｔａ等の炭化物又は窒化物を結合体とした発明が開示されている。
【０００９】
【発明が解決しようとする課題】
上述したような種々の対策により、炭素質耐火物の耐久性の向上が図られてきたが、炭素質耐火物が炭素骨材を主原料とする限り、熱伝導性と耐スラグ性を維持しつつ、炭素質耐火物の短所である加炭溶解速度を低減することには限界がある。
すなわち、上記特公昭５６−１８５５９号公報において開示したように、単に加炭溶解速度を小さくすることにおいては、α−アルミナ等の金属酸化物の添加が効果があることは明らかであり、金属酸化物を多量に含有させることにより加炭溶解速度を極めて小さくすることができるが、同時に耐スラグ性が劣化し、熱伝導率が小さくなるという問題が生じる。
【００１０】
また、高炉炉底部特有の問題として、溶銑流動による内張り炭素質耐火物の摩耗がある。すなわち、出銑によって高炉炉底部には溶銑の環状流が形成されるが、この環状流に沿った部位の炭素質耐火物は、他の部位よりも著しく摩耗することが知られている。特に、炭素骨材を主原料とする炭素質耐火物は溶銑に濡れず、炭素質耐火物表面に保護層を生成することができないため、常に新しい表面が溶銑と接触することになり、溶銑流動に伴って摩耗していく。
【００１１】
このような環状流による内張り炭素質耐火物の摩耗を防ぐために、以下のような提案がなされている。すなわち、特開平９−４１００９号公報においては、ＴｉＯ2源を高炉に装入し、炉底にＴｉ化合物を含む高融点保護層を効率よく堆積させ、炭素質耐火物と溶銑の直接接触を防ぐ方法が提案されている。しかし、高融点保護層と炭素質耐火物は反応あるいは濡れて結合しないため、高融点保護層は炉底部に固定されず、保護層の流失を防ぐことができないのが現状である。
【００１２】
また、特開平６−４８８２０号公報に開示された発明は、溶鋼を対象とする耐火物に関する発明であり、溶銑に対する耐火物の耐食性及び耐スラグ性については何も示唆するところがない。
さらに、特開平７−２５７９８１号公報に開示された発明は、炭素含有耐火物を接合する場合の接合部において、耐食性を損なうことなく高い接合強度を有する耐火物接合体に関するものであり、溶銑に対する耐火物自体の耐食性及び耐スラグ性については何も示唆するところがない。
【００１３】
上述したように、炭素質耐火物の加炭溶解速度を低減し、溶銑に濡れるようにすることで、炭素質耐火物の耐久性は向上するが、従来の方法では、熱伝導性と耐スラグ性を維持しつつ、加炭溶解速度を低減することができず、また、これまでに溶銑に濡れる炭素質耐火物が開示されたことはない。
【００１４】
本発明は、上述したような従来技術の問題点を解決するために提案されたものであり、その目的は、炭素質耐火物の熱伝導性と耐スラグ性を維持しつつ、加炭溶解速度を低減し、且つ、溶鉄特に溶銑に濡れる炭素質耐火物及びその製造方法を提供することにある。
【００１５】
【課題を解決するための手段】
上記の目的を達成するために、本発明者等は、従来から用いられている炭素質耐火物に種々の添加物を加えて、炭素質耐火物の加炭溶解速度を低減し、溶銑に濡れるようにすることができるか否かについて鋭意検討を重ね、本発明を完成するに至ったものである。
【００１６】
すなわち、本発明の要旨とするところは、（１）質量％で、炭素５０〜８０％、アルミナ５〜１５％、金属珪素５〜１５％、及びバナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上を合計で５〜２０％を含有することを特徴とする炭素質耐火物、（２）質量％で、主原料として焙焼無煙炭、仮焼コークス、天然黒鉛もしくは人造黒鉛又はこれらの混合物から成る炭素質原料を５０〜８５％、アルミナ微粉５〜１５％、金属珪素微粉５〜１５％、及びバナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上を合計で５〜２０％を含有させた混合物に有機バインダーを加え、混練、成形し、非酸化雰囲気で焼成して前記(１)記載の炭素質耐火物を得ることを特徴とする炭素質耐火物の製造方法、（３）アルミナの一部又は全部を、ジルコン、マグネシア、ムライト、スピネル及びシリカの１種又は２種以上で置換したことを特徴とする前記(１)記載の炭素質耐火物、（４）アルミナ微粉の一部又は全部を、ジルコン、マグネシア、ムライト、スピネル及びシリカの１種又は２種以上の微粉で置換したことを特徴とする前記(２)記載の炭素質耐火物の製造方法、にある。
【００１７】
上記のような発明を完成するに至った経緯は、以下の通りである。
すなわち、炭素質耐火物は、溶鉄、特に溶銑に触れると炭素骨材が加炭溶解して消耗が起きるが、炭素質耐火物中にアルミナ等が含まれると、炭素骨材溶出後にそれらが炭素質耐火物の表面に残存し、炭素質耐火物と溶鉄の間に介在することにより、炭素質耐火物と溶銑の接触を妨げ、炭素質耐火物の消耗速度を下げることができる。
しかしながら、炭素質耐火物中に多量のアルミナが含有されていると、炭素骨材溶出後の残存アルミナ層が炭素質耐火物の全表面を覆い、その結果、溶鉄・スラグ界面での溶失が加速されるので、溶鉄溶解と耐スラグ性の両者をバランスさせるには、アルミナの含有量を適正な範囲にする必要がある。
【００１８】
一方、本発明の焼成後の耐火物に特有な添加物であるバナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物は、非酸化雰囲気下で使用されることにより、溶鉄、特に溶銑、スラグ及びその界面で溶失しないので、これらを炭素質耐火物に含有させることは、炭素質耐火物の耐溶鉄性、耐スラグ性を改善する。
しかしながら、これらバナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物は高価な原料であることから、炭素骨材溶出後の残存バナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上の層で炭素質耐火物の全表面を覆う量を添加することは、経済的に見合わない。
【００１９】
そのため、安価な原料であるアルミナを炭素質耐火物の耐スラグ性を劣化させない範囲で含有させ、炭素骨材溶出後の残存アルミナ層が炭素質耐火物の全表面を覆うために足りない分をバナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上として含有させることにより、炭素質耐火物の全表面を残存アルミナ層あるいは残存バナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上の層で覆うことができる。これにより、炭素質耐火物の溶銑溶解による消耗が停止し、また、耐スラグ性の劣化も生じない。
【００２０】
さらに、上記バナジウム化合物は、Ｆｅ−Ｖ固溶体を生成する性質を有しているため、炭素質耐火物に炭化、窒化または炭窒化バナジウム化合物を含有させることにより、高炉炉底部に堆積する高融点保護層と炭素質耐火物は結合しやすくなる。その結果、バナジウム化合物を含有した炭素質耐火物を、特に、高炉炉底部の内張り材として用いることにより、高融点保護層は炉底に固定されるので、流動溶銑と炭素質耐火物の直接接触を安定して回避することができ、炭素質耐火物の溶銑流動による摩耗を防止することができる。また、流動溶銑中にバナジウムが溶け出して行くことで、流動溶銑と炭素質耐火物が直接接触することがあっても、溶銑粘度を増加させ、溶銑界面の溶銑流速を低下させることで炭素質耐火物の溶損を防ぐことができる。
なお、本発明者等は、バナジウムだけでなく、ニオブ、タンタル及びこれらの元素の炭化物、窒化物、炭窒化物も同様の作用効果を奏することを確認した。
【００２１】
続いて、本発明の各構成要件の限定理由について説明する。
炭素又は炭素質原料は、熱伝導性を確保するため質量％で５０％以上含有することが必要であり、８５％を超えると気孔径が大となるか、耐溶銑性が劣化するため８５％以下とすることが好ましい。
【００２２】
アルミナ又はアルミナ微粉の含有量は、質量％で５％未満では耐溶鉄性が不足し、１５％を超えると耐スラグ性及び熱伝導率を低下させるので、５〜１５％含有させることが好ましい。また、アルミナの代わりに、ジルコンやマグネシア、ムライト、スピネル、シリカのような高耐火性金属酸化物微粉を含有させても同様の効果が得られることは、先願の特公昭５６−１８５５９号公報に記載の通りである。また、原料となるアルミナ微粉は、粗い粒子だと局所的な溶鉄侵食が進行するため、粒径７４μｍ以下とすることが好ましい。また、焼成時に内部で発生するガスの抜け道を塞ぐことを避けるため、粒径１μｍ以上とすることが好ましい。
【００２３】
金属珪素又は金属珪素微粉の含有量は、質量％で５％未満では気孔細分化効果が不足し、１５％を超えると未反応の金属珪素が残留しやすいので、５〜１５％含有させることが好ましい。また、原料となる金属珪素微粉は、未反応の金属珪素の残留を防ぐため粒径７４μｍ以下とすることが好ましい。また、焼成時に内部で発生するガスの抜け道を塞ぐことを避けるため、粒径１μｍ以上とすることが好ましい。
有機バインダーとしては、コールタールピッチ、フェノール樹脂を用いることができる。
【００２４】
このようにアルミナ及び金属珪素、又はアルミナ微粉及び金属珪素微粉を含有させる効果は公知であるが、本発明においては、さらにバナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上を合計で５〜２０％含有させることを特徴としている。なお、バナジウム、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上の含有量は、質量％で５％未満では耐溶鉄性に対する効果が不足し、２０％を超えると耐溶鉄性に対する効果は変わらず、高コストになるので、５〜２０％含有させることが好ましい。
【００２５】
また、本発明者等は、炭化バナジウム粉末の粒度を種々変えて検討したところ、粒度は小さい方が良く、粒度が３５μｍ以下でも本発明の効果は得られるが、好ましくは１０μｍ以下が良いことが判明した。特に、粒度を２μｍ程度とすると、炭化バナジウム粉末の含有量が５％程度でも十分良好な結果が得られた。
【００２６】
また、炭化バナジウム粉末の代わりに、バナジウム粉末、窒化バナジウム粉末あるいは炭窒化バナジウム（ＶＣxＮy；０＜ｘ，ｙ＜１、且つｘ＋ｙ＝１）粉末を含有させても同様の効果が得られ、また、これら炭化バナジウム，窒化バナジウム，炭化バナジウム、炭窒化バナジウムの１種又は２種以上を任意の割合で混合した混合物を、５〜２０％含有させても同様の効果が得られることが判明した。
【００２７】
また、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物についても同様の効果が得られることを確認した。但し、ニオブ、タンタル、又はこれらの元素の炭化物、窒化物、炭窒化物の１種又は２種以上を添加する場合は、耐溶銑浸食率の効果が大きいので、４０質量％まで添加しても良い。
【００２８】
なお、本発明に係るバナジウムは、金属、炭化物、窒化物又は炭窒化物の状態の原料を使用しても良い。また、ニオブ、タンタルも、金属、炭化物、窒化物又は炭窒化物の状態の原料を使用しても良い。
また、前記（１）又は（３）に係わる本発明の耐火物は、前記（２）又は（４）に係わる耐火物原料を非酸化雰囲気下で焼成することにより製造することができる。非酸化雰囲気としては、コークス中、真空容器中、Ｎ2やＡｒ等不活性雰囲気中で実施すればよい。また、混練、成形後、１００〜５００℃で１０〜５０時間熱処理することにより、いわゆる非焼成耐火物として製造することもできる。
【００２９】
さらに、本発明の炭素質耐化物は主に高炉炉底部用として説明したが、合金鉄用電気炉、キュポラ等、非酸化雰囲気で使用されるのであれば、特に用途を限定することなく、溶鉄に濡れやすく、耐食性、耐摩耗性に優れるという効果が得られる。
【００３０】
【実施例】
本発明に係る実施例及び比較例について、以下の各項目について検討した。
［１．炭化バナジウムを含有することの効果について］
表１に示す配合に従って、後述する手順で、炭化バナジウムを含有する実施例１〜３及び炭化バナジウムを含まない比較例の炭素質耐火物を得た。焼成はコークス中で実施した。そして、実施例１〜３及び比較例の炭素質耐火物を、１５５０℃において上面に高炉スラグ溶融層を有する高炉銑鉄中に１時間浸漬及び回転させた後、試料を回収し、溶銑浸漬部及び溶銑・スラグ界面の侵食率を調べた。溶銑源としては、鋳鉄（ＪＩＳ ＦＣ−１５、Ｃ量３．５％、Ｓｉ量２．９％）を１．２ｋｇ／回用いた。また、溶銑へのＡｒの吹き込み量は４０ｍｌ／ｍｉｎであり、この溶銑中に、試料を１５５０℃で１時間回転浸漬させた。
【００３１】
なお、成形サイズはφ１００×１５０ｍｍ、溶銑試験試料形状は３０φ×１２０ｍｍである。また、溶損指数は、減圧槽内に高周波溶解炉を備えた耐食性評価装置を用いて侵食試験を行い、侵食試験前後の試料径を測定し、次式から求め、比較例の溶銑浸漬部及び溶銑・スラグ界面の浸食率を１００として比較した。結果は表１に示した通りである。
【数１】
（実施例１）
人造黒鉛６６．５部の炭素原料に粒径２〜３μｍのアルミナ微粉１２部、粒径２〜３μｍの金属珪素微粉１１．５部を加え、さらに粒度７μｍ以下の炭化バナジウム微粉１０部を加えた計１００部の原料に、有機バインダーとしてフェノール樹脂とコールタールピッチを合わせて外掛けで１６部を加え、混練し、成形圧力２０ＭＰａで型込め成形した。さらに、この成形体をコークスブリーズ中に埋没して非酸化雰囲気で１２５０℃で焼成し、炭素質耐火物を得た。
【００３３】
（実施例２）
人造黒鉛６１．５部の炭素原料と粒度７μｍ以下の炭化バナジウム微粉１５部を加えた他は実施例１と同様に製造し、炭素質耐火物を得た。
（実施例３）
人造黒鉛５６．５部の炭素原料と粒度７μｍ以下の炭化バナジウム微粉２０部を加えた他は実施例１と同様に製造し、炭素質耐火物を得た。
【００３４】
（比較例）
表１に示したように、比較例においては、人造黒鉛７６．５部の炭素原料に粒径２〜３μｍのアルミナ微粉１２部、粒径７４μｍ以下の金属珪素微粉１１．５部を加えた計１００部の原料に、実施例１と同様に、有機バインダーとしてフェノール樹脂とコールタールピッチを合わせて外掛けで１６部を加え、混練し、成形圧力２０ＭＰａで型込め成形した。さらに、この成形体をコークスブリーズ中に埋没して非酸化雰囲気で１２５０℃で焼成し、炭素質耐火物を得た。
【表１】
表１から明らかなように、炭化バナジウムを１０〜２０質量％含有する実施例１〜３は、溶銑浸漬部の耐食性が比較例と同等であったが、溶銑・スラグ界面での耐食性は１０％前後改善された。
【００３６】
［２．炭化ニオブを含有することの効果について］
表２に示す配合に従って、上記実施例１と同様の手順で、ＮｂＣの配合比を１０〜２０％の範囲で変えて実施例４〜６の炭素質耐火物を得た。アルミナの粒径は２〜３μｍ、金属珪素の粒径は７４μｍ以下とした。ただし、ＮｂＣの粒度は７μｍ以下である。そして、これら実施例４〜６の試料を実施例１と同様の条件で侵食試験を行った。結果は表２に示した通りである。
【表２】
表２から明らかなように、ＮｂＣの含有量が１０〜２０質量％である実施例４〜６は、溶銑浸漬部の侵食率が比較例と比べ３０〜４０％程度低減し、さらに溶銑・スラグ界面での侵食率も、比較例と同等程度〜１５％程度低減した。
【００３８】
［３．炭化タンタルを含有することの効果について］
表３に示す配合に従って、上記実施例１と同様の手順で、ＴａＣの配合比を１０〜２０％の範囲で変えて実施例７〜９の炭素質耐火物を得た。アルミナの粒径は２〜３μｍ、金属珪素の粒径は７４μｍ以下とした。ただし、ＴａＣの粒度は７μｍ以下である。そして、これら実施例７〜９の試料を実施例１と同様の条件で侵食試験を行った。結果は表３に示した通りである。
【表３】
表３から明らかなように、ＴａＣの含有量が１０〜２０質量％である実施例７〜９は、溶銑浸漬部の侵食率が比較例と比べ２５〜３５％程度低減し、さらに溶銑・スラグ界面での耐食性も１０〜３０％程度まで改善され、良好な結果が得られた。
【００４０】
【発明の効果】
以上説明したように、本発明の炭素質耐火物を高炉湯溜まりの側壁部及び炉底部の内張り材に使用すれば、内張り材の溶銑溶解による消耗が減少すると同時に、高融点保護層が炉底に固定されることにより、流動溶銑による摩耗も減少し、高炉の寿命を延ばすことができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refractory used in a non-oxidizing atmosphere, particularly a carbonaceous refractory suitable for a lining material for a side wall portion and a bottom portion of a blast furnace hot water pool, and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, furnaces with a non-oxidizing atmosphere, such as blast furnaces, have become increasingly large in size and have become harsh, and the causes of damage to lining refractories have increased due to high-pressure operations, pulverized coal injection operations, etc. Long life is desired in order to reduce initial investment. The rate limiting of the life of such a blast furnace is the durability of the lining material of the side wall part and bottom part of the blast furnace hot water pool. Carbonaceous refractories are used as the lining material for the side walls and bottom of the blast furnace hot water pool. That is, the improvement in the durability of the carbonaceous refractory used as the lining material has a direct effect on the life extension of the blast furnace.
[0003]
Carbonaceous refractories are generally mixed with carbon aggregates such as roasted anthracite, artificial graphite, natural graphite, and organic binders such as coal tar pitch and phenol resin, then extruded or molded and then coke. Manufactured by burying in a breeze and firing. Carbonaceous refractories also have the disadvantage of causing erosion due to carburizing and dissolution of carbon aggregates in hot metal compared to clay bricks, but they have high thermal conductivity and are also resistant to slag. Since it is excellent, it has been used for the lining material of the blast furnace pool.
[0004]
In addition, the cause of damage to the carbonaceous refractory lining in the blast furnace is the cracking caused by the dissolution of carburizing into the hot metal, the intrusion of hot metal into the pores, the intrusion and reaction of alkali or zinc vapor. Generation, destruction due to thermal stress, wear due to hot metal flow, and the like.
[0005]
For this reason, many proposals have been made and implemented in the past for the purpose of improving the durability of carbonaceous refractories, such as the composition, manufacturing method, and usage of carbonaceous refractories. In the present applicant as well, in order to reduce the rate of carburizing dissolution in hot metal, Japanese Patent Publication No. 56-18559 discloses metal oxidation of α-alumina, zircon, magnesia, etc. in addition to the carbon aggregate of the main raw material. Disclosed is a carbonaceous refractory for a blast furnace containing a product.
[0006]
In Japanese Patent Publication No. 58-43350, carbon aggregate is used as a main raw material, metal silicon fine powder is blended, and a whisker-like silicon compound is generated in the pores of the carbonaceous refractory during the firing process. Disclosed is a method for producing a carbonaceous refractory for a blast furnace that reduces the number of pores having a diameter of 1 μm or more that can penetrate and reduces the penetration of hot metal or reactive gas into the carbonaceous refractory.
[0007]
Furthermore, in JP-A-8-81706, in order to increase thermal conductivity, when a carbon aggregate such as artificial graphite or natural graphite having a high thermal conductivity is used as a main raw material, the carburization dissolution rate is low, and A method for producing a carbonaceous refractory for a blast furnace that can stably produce a large carbonaceous refractory having a small pore diameter has been disclosed.
[0008]
Japanese Patent Laid-Open No. 6-48820 discloses an invention in which Ta, Nb or carbides thereof are added to a carbon-containing refractory material used in a steel manufacturing process, and Japanese Patent Laid-Open No. 7-257981 is disclosed. In the case of joining carbon-containing refractories, an invention in which a carbide or nitride such as Nb, V, Ta or the like is used as a combined body is disclosed in order to obtain high joint strength.
[0009]
[Problems to be solved by the invention]
Although various measures as described above have improved the durability of carbonaceous refractories, as long as the carbonaceous refractory is mainly made of carbon aggregate, it maintains thermal conductivity and slag resistance. However, there is a limit to reducing the carburization dissolution rate, which is a disadvantage of carbonaceous refractories.
That is, as disclosed in the above Japanese Patent Publication No. 56-18559, it is clear that the addition of a metal oxide such as α-alumina is effective in simply reducing the carburization dissolution rate. Although the carburization dissolution rate can be made extremely small by containing a large amount of substances, there is a problem that the slag resistance is deteriorated at the same time and the thermal conductivity is reduced.
[0010]
Also, as a problem peculiar to the bottom of the blast furnace, there is wear of the lining carbonaceous refractory due to molten metal flow. In other words, it is known that an annular flow of hot metal is formed at the bottom of the blast furnace furnace due to the dredging, but the carbonaceous refractory in the portion along the annular flow is significantly worn more than other portions. In particular, carbon refractories made mainly of carbon aggregates do not get wet with the hot metal, and a protective layer cannot be formed on the surface of the carbonaceous refractory. It wears with it.
[0011]
In order to prevent the lining carbonaceous refractory from being worn by such an annular flow, the following proposals have been made. That is, in JP-A-9-41009, a TiO 2 source is charged into a blast furnace, and a high melting point protective layer containing a Ti compound is efficiently deposited on the furnace bottom to prevent direct contact between the carbonaceous refractory and hot metal. A method has been proposed. However, since the high-melting point protective layer and the carbonaceous refractory do not react or get bonded to each other, the high-melting point protective layer is not fixed to the bottom of the furnace, so that the protective layer cannot be prevented from being lost.
[0012]
The invention disclosed in Japanese Patent Laid-Open No. 6-48820 is an invention relating to a refractory for molten steel, and there is no suggestion about the corrosion resistance and slag resistance of the refractory against hot metal.
Furthermore, the invention disclosed in Japanese Patent Application Laid-Open No. 7-257981 relates to a refractory joined body having a high joining strength without impairing corrosion resistance in a joining portion in the case of joining a carbon-containing refractory. There is no suggestion about the corrosion resistance and slag resistance of the refractory itself.
[0013]
As described above, the carbonaceous refractory is improved in durability by reducing the carbonization dissolution rate of the carbonaceous refractory and soaking it in the hot metal. However, the conventional method improves the thermal conductivity and slag resistance. Carbonaceous refractories that have not been able to reduce the rate of carburizing dissolution while maintaining the properties and get wet with the hot metal have never been disclosed.
[0014]
The present invention has been proposed in order to solve the problems of the prior art as described above, and its purpose is to maintain the thermal conductivity and slag resistance of the carbonaceous refractory while at the same time dissolving the carburization. And to provide a carbonaceous refractory material that can be wetted by molten iron, particularly hot metal, and a method for producing the same.
[0015]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventors add various additives to the conventionally used carbonaceous refractories, reduce the rate of carburizing dissolution of carbonaceous refractories, and get wet with hot metal. As a result, the present invention has been completed.
[0016]
That is, the gist of the present invention is (1) mass%, carbon 50-80%, alumina 5-15%, metal silicon 5-15%, and vanadium, niobium, tantalum, or carbides of these elements. , A carbonaceous refractory containing a total of 5 to 20% of one or more of nitrides and carbonitrides, (2) roasted anthracite as a main raw material, calcined 50 to 85% carbonaceous raw material made of coke, natural graphite or artificial graphite or a mixture thereof, alumina fine powder 5 to 15%, metal silicon fine powder 5 to 15%, and vanadium, niobium, tantalum, or carbides of these elements In addition, an organic binder is added to a mixture containing 5 to 20% in total of one or more of nitride and carbonitride, kneaded, molded, and baked in a non-oxidizing atmosphere. Obtaining carbon refractories (3) A part or all of alumina is substituted with one or more of zircon, magnesia, mullite, spinel, and silica. (1) (4) The carbonaceous refractory according to (4), wherein a part or all of the fine alumina powder is replaced with one or more fine powders of zircon, magnesia, mullite, spinel and silica. The manufacturing method of the carbonaceous refractory described.
[0017]
The background to the completion of the invention as described above is as follows.
That is, when carbonaceous refractories come into contact with molten iron, especially hot metal, the carbon aggregates are carburized and melted, and wear occurs. However, if the carbonaceous refractories contain alumina or the like, they are carbonized after elution of the carbon aggregates. By remaining on the surface of the refractory refractory and being interposed between the carbon refractory and the molten iron, the contact between the refractory and the hot metal can be prevented, and the consumption rate of the refractory can be reduced.
However, if a large amount of alumina is contained in the carbonaceous refractory, the residual alumina layer after elution of the carbon aggregate covers the entire surface of the carbonaceous refractory, and as a result, the molten iron / slag interface is lost. Since it accelerates, in order to balance both molten iron melt | dissolution and slag resistance, it is necessary to make content of an alumina into an appropriate range.
[0018]
On the other hand, vanadium, niobium, tantalum, or the carbides, nitrides, and carbonitrides of these elements, which are additives specific to the refractory after firing of the present invention, are used in a non-oxidizing atmosphere. In particular, since it does not melt at the hot metal, slag and its interface, the inclusion of these in the carbonaceous refractory improves the molten iron resistance and slag resistance of the carbonaceous refractory.
However, since vanadium, niobium, tantalum, or carbides, nitrides, and carbonitrides of these elements are expensive raw materials, residual vanadium, niobium, tantalum, or carbides of these elements after elution of carbon aggregates Addition of an amount covering the entire surface of the carbonaceous refractory with one or more layers of nitride, carbonitride is not economical.
[0019]
Therefore, alumina, which is an inexpensive raw material, is contained in a range that does not deteriorate the slag resistance of the carbonaceous refractory, and the remaining alumina layer after elution of the carbon aggregate is insufficient to cover the entire surface of the carbonaceous refractory. By containing vanadium, niobium, tantalum, or one or more of carbides, nitrides, carbonitrides of these elements, the entire surface of the carbonaceous refractory is left as a residual alumina layer or residual vanadium, niobium, tantalum. Or one or more layers of carbides, nitrides, and carbonitrides of these elements. As a result, the consumption of the carbonaceous refractory due to melting of the hot metal is stopped, and the slag resistance is not deteriorated.
[0020]
Furthermore, since the vanadium compound has the property of generating an Fe-V solid solution, high-melting point protection deposited at the bottom of the blast furnace furnace by adding a carbonized refractory to the carbonized, nitrided or vanadium carbonitride compound. Layers and carbonaceous refractories are more likely to bond. As a result, by using a carbonaceous refractory containing a vanadium compound, especially as a lining material at the bottom of the blast furnace furnace, the high melting point protective layer is fixed to the furnace bottom, so that the molten metal and carbonaceous refractory are in direct contact with each other. Can be avoided stably, and wear due to the hot metal flow of the carbonaceous refractory can be prevented. In addition, vanadium is melted into the flowing hot metal, so that even if the flowing hot metal and the carbonaceous refractory are in direct contact with each other, the hot metal viscosity is increased and the hot metal flow rate at the hot metal interface is decreased. Refractory melting can be prevented.
The present inventors have confirmed that not only vanadium but also niobium, tantalum and carbides, nitrides, and carbonitrides of these elements have the same effect.
[0021]
Then, the reason for limitation of each component requirement of this invention is demonstrated.
Carbon or a carbonaceous raw material needs to be contained in an amount of 50% or more by mass% in order to ensure thermal conductivity. If it exceeds 85%, the pore diameter becomes large or the hot metal resistance deteriorates and 85%. The following is preferable.
[0022]
If the content of alumina or fine alumina powder is less than 5% by mass, the resistance to molten iron is insufficient, and if it exceeds 15%, the slag resistance and thermal conductivity are lowered, so 5-15% is preferable. Also, it is known that the same effect can be obtained by adding fine refractory metal oxide fine powders such as zircon, magnesia, mullite, spinel and silica instead of alumina. As described in. The alumina fine powder as a raw material is preferably a particle size of 74 μm or less because local erosion of molten iron proceeds when it is coarse. Moreover, in order to avoid closing the escape route of the gas generated inside at the time of baking, it is preferable that the particle diameter be 1 μm or more.
[0023]
When the content of metal silicon or metal silicon fine powder is less than 5% by mass, the pore refining effect is insufficient, and when it exceeds 15%, unreacted metal silicon tends to remain. preferable. Further, the metal silicon fine powder as a raw material preferably has a particle size of 74 μm or less in order to prevent unreacted metal silicon from remaining. Moreover, in order to avoid closing the escape route of the gas generated inside at the time of baking, it is preferable that the particle diameter be 1 μm or more.
As the organic binder, coal tar pitch or phenol resin can be used.
[0024]
Thus, the effect of containing alumina and metal silicon, or alumina fine powder and metal silicon fine powder is known, but in the present invention, vanadium, niobium, tantalum, or carbide, nitride, carbonitride of these elements. It is characterized by containing 5 to 20% in total of 1 type or 2 types or more. In addition, if the content of one or more of vanadium, niobium, tantalum, or carbides, nitrides, and carbonitrides of these elements is less than 5% by mass, the effect on molten iron resistance is insufficient. If it exceeds 50%, the effect on the molten iron resistance does not change and the cost increases, so it is preferable to contain 5 to 20%.
[0025]
In addition, the present inventors have studied variously changing the particle size of vanadium carbide powder. As a result, it is better that the particle size is smaller, and the effect of the present invention can be obtained even if the particle size is 35 μm or less, but preferably 10 μm or less. found. In particular, when the particle size was about 2 μm, sufficiently good results were obtained even when the content of vanadium carbide powder was about 5%.
[0026]
Further, the same effect can be obtained by including vanadium powder, vanadium nitride powder or vanadium carbonitride (VC x N y ; 0 <x, y <1, and x + y = 1) powder instead of vanadium carbide powder. In addition, it is found that the same effect can be obtained even if 5 to 20% of a mixture obtained by mixing one or more of these vanadium carbide, vanadium nitride, vanadium carbide, and vanadium carbonitride in an arbitrary ratio is contained. did.
[0027]
Further, it was confirmed that the same effect can be obtained with niobium, tantalum, or carbides, nitrides, and carbonitrides of these elements. However, when adding one or more of niobium, tantalum, or carbides, nitrides, and carbonitrides of these elements, the effect of the hot metal erosion resistance is great, so even if it is added up to 40% by mass. good.
[0028]
The vanadium according to the present invention may use a raw material in the state of metal, carbide, nitride or carbonitride. Niobium and tantalum may also be used in the form of metals, carbides, nitrides or carbonitrides.
The refractory according to the present invention according to (1) or (3) can be produced by firing the refractory material according to (2) or (4) in a non-oxidizing atmosphere. The non-oxidizing atmosphere, coke, vacuum chamber, may be carried out in N 2 or Ar Hitoshifu in inert atmosphere. Moreover, it can also manufacture as what is called a non-baking refractory by heat-processing at 100-500 degreeC for 10 to 50 hours after kneading | mixing and shaping | molding.
[0029]
Furthermore, although the carbonaceous refractory of the present invention has been explained mainly for blast furnace bottoms, it can be used in a non-oxidizing atmosphere such as an iron furnace for alloy iron, cupola, etc. It is easy to get wet and has the effect of being excellent in corrosion resistance and wear resistance.
[0030]
【Example】
The following items were examined in the examples and comparative examples according to the present invention.
[1. Regarding the effect of containing vanadium carbide]
According to the composition shown in Table 1, Examples 1 to 3 containing vanadium carbide and a carbonaceous refractory of a comparative example not containing vanadium carbide were obtained by the procedure described later. Firing was carried out in coke. And after immersing and rotating the carbonaceous refractories of Examples 1 to 3 and the comparative example in a blast furnace pig iron having a blast furnace slag melt layer on the upper surface at 1550 ° C. for 1 hour, a sample was collected, The erosion rate of the hot metal / slag interface was investigated. As the hot metal source, cast iron (JIS FC-15, C amount 3.5%, Si amount 2.9%) was used 1.2 kg / time. The amount of Ar blown into the hot metal was 40 ml / min, and the sample was rotated and immersed in the hot metal at 1550 ° C. for 1 hour.
[0031]
The molding size is φ100 × 150 mm, and the hot metal test sample shape is 30φ × 120 mm. The erosion index is determined by performing an erosion test using a corrosion resistance evaluation apparatus equipped with a high-frequency melting furnace in a decompression tank, measuring the sample diameter before and after the erosion test, and obtaining from the following formula: The comparison was made assuming that the erosion rate at the hot metal / slag interface was 100. The results are as shown in Table 1.
[Expression 1]
Example 1
12 parts of alumina fine powder with a particle size of 2 to 3 μm, 11.5 parts of metal silicon fine powder with a particle size of 2 to 3 μm, and 10 parts of vanadium carbide fine powder with a particle size of 7 μm or less were added to 66.5 parts of artificial graphite. A total of 100 parts of the raw material was combined with phenol resin and coal tar pitch as organic binders, and 16 parts were added by external hooking, kneaded, and mold-molded at a molding pressure of 20 MPa. Furthermore, this compact was embedded in coke breeze and fired at 1250 ° C. in a non-oxidizing atmosphere to obtain a carbonaceous refractory.
[0033]
(Example 2)
A carbonaceous refractory was obtained in the same manner as in Example 1 except that 61.5 parts of artificial graphite and 15 parts of vanadium carbide fine powder having a particle size of 7 μm or less were added.
(Example 3)
A carbonaceous refractory was obtained in the same manner as in Example 1 except that 56.5 parts of artificial graphite and 20 parts of vanadium carbide fine powder having a particle size of 7 μm or less were added.
[0034]
(Comparative example)
As shown in Table 1, in the comparative example, a carbon raw material of 76.5 parts of artificial graphite was added with 12 parts of alumina fine powder having a particle diameter of 2 to 3 μm and 11.5 parts of metal silicon fine powder having a particle diameter of 74 μm or less. In the same manner as in Example 1, 100 parts of the raw material was added with phenol resin and coal tar pitch as organic binders, and 16 parts were added as an outer shell, kneaded, and molded by molding at a molding pressure of 20 MPa. Furthermore, this compact was embedded in coke breeze and fired at 1250 ° C. in a non-oxidizing atmosphere to obtain a carbonaceous refractory.
[Table 1]
As is clear from Table 1, Examples 1 to 3 containing vanadium carbide in an amount of 10 to 20% by mass had the same corrosion resistance as that of the comparative example, but the corrosion resistance at the hot metal / slag interface was 10%. Improved before and after.
[0036]
[2. Effect of containing niobium carbide]
According to the composition shown in Table 2, carbon black refractories of Examples 4 to 6 were obtained in the same procedure as in Example 1 above, except that the NbC compounding ratio was changed in the range of 10 to 20%. The particle size of alumina was 2 to 3 μm, and the particle size of metallic silicon was 74 μm or less. However, the particle size of NbC is 7 μm or less. Then, the samples of Examples 4 to 6 were subjected to erosion tests under the same conditions as in Example 1. The results are as shown in Table 2.
[Table 2]
As is apparent from Table 2, in Examples 4 to 6 in which the content of NbC is 10 to 20% by mass, the erosion rate of the hot metal immersion part is reduced by about 30 to 40% compared to the comparative example, and the hot metal / slag is further reduced. The erosion rate at the interface was also reduced by about 15% to about the same as the comparative example.
[0038]
[3. Effect of containing tantalum carbide]
According to the composition shown in Table 3, carbon refractories of Examples 7 to 9 were obtained by changing the TaC compounding ratio in the range of 10 to 20% in the same procedure as in Example 1. The particle size of alumina was 2 to 3 μm, and the particle size of metallic silicon was 74 μm or less. However, the grain size of TaC is 7 μm or less. The samples of Examples 7 to 9 were subjected to erosion tests under the same conditions as in Example 1. The results are as shown in Table 3.
[Table 3]
As is apparent from Table 3, in Examples 7 to 9 in which the content of TaC is 10 to 20% by mass, the erosion rate of the hot metal immersion part is reduced by about 25 to 35% compared to the comparative example, and the hot metal and slag are further reduced. Corrosion resistance at the interface was also improved to about 10 to 30%, and good results were obtained.
[0040]
【The invention's effect】
As described above, if the carbonaceous refractory according to the present invention is used for the lining material of the side wall portion and the bottom portion of the blast furnace hot water pool, the wear due to melting of the lining material is reduced, and at the same time, the high melting point protective layer is By being fixed to, the wear due to fluidized hot metal is reduced and the life of the blast furnace can be extended.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001291521A JP4537632B2 (en) | 2001-09-25 | 2001-09-25 | Carbonaceous refractory and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001291521A JP4537632B2 (en) | 2001-09-25 | 2001-09-25 | Carbonaceous refractory and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003095742A JP2003095742A (en) | 2003-04-03 |
| JP4537632B2 true JP4537632B2 (en) | 2010-09-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP2001291521A Expired - Lifetime JP4537632B2 (en) | 2001-09-25 | 2001-09-25 | Carbonaceous refractory and method for producing the same |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5082112A (en) * | 1973-11-24 | 1975-07-03 | ||
| JPS5617985A (en) * | 1979-07-18 | 1981-02-20 | Mitsubishi Metal Corp | Graphite member for high temperature furnace |
| JPH06101975A (en) * | 1992-09-21 | 1994-04-12 | Akechi Ceramics Kk | Blast furnace lining carbonaceous refractories |
| JPH0881706A (en) * | 1994-09-14 | 1996-03-26 | Nippon Steel Corp | Production of carbon refractories for blast furnace |
| JPH1053454A (en) * | 1996-08-09 | 1998-02-24 | Toshiba Ceramics Co Ltd | Production of carbon containing refractory |
-
2001
- 2001-09-25 JP JP2001291521A patent/JP4537632B2/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5082112A (en) * | 1973-11-24 | 1975-07-03 | ||
| JPS5617985A (en) * | 1979-07-18 | 1981-02-20 | Mitsubishi Metal Corp | Graphite member for high temperature furnace |
| JPH06101975A (en) * | 1992-09-21 | 1994-04-12 | Akechi Ceramics Kk | Blast furnace lining carbonaceous refractories |
| JPH0881706A (en) * | 1994-09-14 | 1996-03-26 | Nippon Steel Corp | Production of carbon refractories for blast furnace |
| JPH1053454A (en) * | 1996-08-09 | 1998-02-24 | Toshiba Ceramics Co Ltd | Production of carbon containing refractory |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003095742A (en) | 2003-04-03 |
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