JP3703104B2 - Magnesia-chromic unfired brick - Google Patents
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Description
【０００１】
【産業上の利用分野】
本発明は耐食性および耐熱スポーリング性に優れたマグネシア−クロム質不焼成れんがに関するものである。
【０００２】
【従来の技術】
マグネシア質れんがは融点が高く、さらに金属精錬中に発生する塩基性スラグに対する侵食抵抗性が優れていることから金属精錬用容器内張り耐火物として多量に使用されている。
しかし、前記した特長にもかかわらずマグネシア質れんがは耐熱スポーリング性および耐構造的スポーリング性に劣り、マグネシア質れんがを内張りした容器は寿命が短いという欠点がある。なお、構造的スポーリングとはスラグ浸透により原質部と著しく組織を異にした変質部が発生し、この変質部が容器使用中の温度の急激な上昇または下降により原質部から剥離する現象である。
【０００３】
そこで、このようなマグネシア質れんがの剥離を防止する方策としてマグネシア質原料とクロム鉄鉱とを組み合わせて材料とすることが考えられている。
マグネシア質原料とクロム鉄鉱を主骨材とするマグネシア−クロム質れんがは耐食性、耐熱スポーリング性に優れており、従来より製鋼プロセスで、ＲＨ、ＤＨなどの溶鋼真空脱ガス炉やＡＯＤ炉などの内張り材として使用されている。
マグネシア−クロム質れんがはその原料構成からダイレクトボンドれんがとリボンドれんがに大別できる。前者はマグネシア源として高純度の合成マグネシアクリンカーを、またクロム源としては天然のクロム鉄鉱を使用しており、これらの配合物に適当な結合剤を加えて成形し、１７００℃以上の高温で焼成して製造される。一方、後者はマグネシアクリンカーとクロム鉄鉱を事前にロータリーキルンやトンネルキルンなどで高温焼結した焼結マグクロクリンカーを使用し、前者と同様に成形して得られるものである。
【０００４】
マグネシア−クロム質れんがの耐食性の向上を主眼とした材質改善は従来から盛んに行われている。例えば、特公昭６３−３１４２８号公報では高純度のマグネシアクリンカーおよびシリカ成分の少ないクロム鉄鉱を使用し、また特開平２−１９６０６３号公報では酸化クロムを多量使用し、酸化クロムとマグネシアクリンカーの間に強固なピクロクロマイト結合を生成し、さらに酸化クロムの気孔および低膨張性によって熱衝撃歪を吸収し、耐食性と耐熱スポーリング性を同時に満足したマグネシア−クロム質れんがが紹介されている。
【０００５】
【発明が解決しようとする課題】
近年、高級鋼の需要が増大するにしたがってマグネシア−クロム質れんがは二次精錬炉などの特殊精錬炉に使用され、スラグや溶鋼摩耗などの過酷な条件が増大しており、上記従来のマグネシア−クロム質れんがでは十分な寿命が得られていない。さらに最近ではスプラッシュによる地金の付着防止および極低炭素鋼の生産に対し、酸素吹き込み操業が増え、より一層の耐食性の向上が求められている。
しかし、その反面、粗鋼生産量の低下とともに耐食性および耐熱スポーリング性に優れた安価品のマグネシア−クロム質れんがも求められている。
【０００６】
本発明は、上記社会情勢をふまえ、従来の高価なマグネシア−クロム質焼成れんが（以下、焼成品と称する）に代わり安価なマグネシア−クロム質不焼成れんが（以下、不焼成品と称する）を提供し、従来の焼成品と同等以上の耐食性および耐熱スポーリング性を確保し、耐用性の向上を図ることを目的とする。
【０００７】
【課題を解決するための手段】
本発明者らは、上記の課題に基づき従来の焼成品に代わるものとして、安価な不焼成品を得るため実験検討を重ねた。
その結果、不焼成品は使用中の高温度で稼働面の近傍にスピネル生成物を生成させることを知り、さらに後述のＡｌ2Ｏ3とＴｉＯ2との作用により焼成品と同等以上に耐食性、耐熱スポーリング性が向上することを確認し、本発明を完成させたものである。
焼成品は耐食性向上のためピクロクロマイトなどのスピネル生成物を発生させるべく高温焼成を行っている。しかし焼成工程が製造原価に影響を及ぼし、それにともない価格も高くなっている。本発明の不焼成品はその問題を解決したものである。
【０００８】
すなわち、本願の特定発明は、 それぞれ粒度調整された高純度のマグネシア質原料、クロミア系原料、アルミナ質原料およびチタニア質原料とを主材とする配合組成を結合剤と共に混練し、成形し、乾燥したマグネシア−クロム質不焼成れんがであって、前記配合組成中のＡｌ２Ｏ３ の化学成分が２〜１５ｗｔ％であり、ＴｉＯ２ の化学成分が２〜１０ｗｔ％であることを特徴とする。
【０００９】
以下、本発明について詳細に説明する。
本発明で使用できるマグネシア質原料、アルミナ質原料の具体例は天然原料または人工原料による焼結品または電融品から選ばれる一種または二種以上が使用できる。純度は特に本発明の効果に影響するものではないが、ＭｇＯ成分、Ａｌ2Ｏ3成分が９５％以上の高純度のもの、つまり不純物の少ないものを使用するのが望ましい。粒度は従来の焼成品と同様、密充填組織が得られるように粗粒、中粒、微粒に調整する。
【００１０】
クロミア系原料としては、クロム鉄鉱、酸化クロム、マグクロクリンカーが使用できる。
クロム鉄鉱は例えば、パキスタンクロム鉄鉱、トルコクロム鉄鉱、マシンロッククロム鉄鉱、日本クロム鉄鉱、トランスバールクロム鉄鉱などが使用でき、不純物の少ないものを使用するのが望ましい。
クロム鉄鉱の構成成分は使用中にマグネシア質原料のＭｇＯ成分と反応して複合スピネル組織を生成し、骨材間を強固に結合させる作用をもつ。
酸化クロムは従来の材質の耐火物と同様に、純度９０％以上の市販品が使用できる。また、酸化クロムはスラグや溶鋼の浸透防止効果があり、市販されている酸化クロムが微粉であることをあることを考えるとマトリックス粉として用いられる。
また、マグクロクリンカーについては、マグネシアクリンカーとクロム鉄鉱または酸化クロムを電気炉で電気溶融して得られる電融マグクロクリンカーや既述の焼結マグクロクリンカーが使用できる。
【００１１】
チタニア質原料はルチル型またはアナターゼ型またはこれらの併用でもよい。アルミナ質原料やチタニア質原料は反応性を増すためにマトリックス粉として添加するのが望ましい。これらの混合物を混練・成形・乾燥して不焼成品として使用した場合、使用時の高温により、稼働面近傍で
【００１２】
この固溶体とＭｇＯ粒子との境界部には膨張収縮によるヘアクラックが発生するか、もしくはこの固溶体部分が骨材粒子間隙部に移動して間隙部を充填するためポアの径が小さくなる。
すなわち、ヘアクラックの発生により耐熱スポーリング性が向上し、ポアの径が小さくなることによってスラグや溶鋼の浸透を防止でき耐食性の向上をもたらす。つまり不焼成品として従来の焼成品よりも耐用性の向上が図れるというものである。
【００１３】
Ａｌ２Ｏ３およびＴｉＯ２の化学成分は、配合組成中、Ａｌ２Ｏ３：２〜１５ｗｔ％、ＴｉＯ２：２〜１０ｗｔ％とする。その理由は以下の通りである。つまり、前記（１）〜（３）式に基づく固溶体反応でポア径を小さくするには、ＴｉＯ２／Ａｌ２Ｏ３のモル比は１．０が望ましく、また、ＴｉＯ２が２ｗｔ％未満では添加したＴｉＯ２はＭｇＯ粒界に主に分布するのでＴｉＯ２の効果が得られない。一方、ＴｉＯ２が１０ｗｔ％を超えると、前記（１）〜（３）式の固溶体反応にあずからない未反応のＴｉＯ２がＭｇＯ粒界に多量に分布し、ＭｇＯ粒子の崩壊をもたらし耐食性の低下をまねくのでＴｉＯ２の化学成分は２〜１０ｗｔ％に制限される。よってＴｉＯ２／Ａｌ２Ｏ３のモル比が１．０に、したがって、Ａｌ２Ｏ３の化学成分は２〜１５ｗｔ％が望ましい。
【００１４】
本発明の不焼成品は、強度を付与するため、さらに耐食性、耐構造的スポーリング性を向上させるために下記金属粉末の１種以上、もしくは酸化物やカーボンの１種以上を併用添加することができる。
金属粉末の例として、金属Ａｌ、金属Ｍｇ、金属Ｓｉ、Ｍｇ−Ａｌ合金などが挙げられ、添加量は１〜１０ｗｔ％が好ましい。
酸化物の例として、ＳｉＯ2、ＺｒＯ2、Ｆｅ2Ｏ3などが挙げられ、添加量は１〜２０ｗｔ％が好ましい。
【００１５】
上記の金属粉末、酸化物を添加する理由は以下の通りである。
すなわち、金属粉末や酸化物は強度を付与するための焼結助剤として作用し、例えば、（Ｆｅ，Ｍｇ）Ｏ・（Ｚｒ，Ｆｅ）2Ｏ3なる一般式で示される複合スピネルを生成し、耐食性を向上させるからである。
【００１６】
金属粉末、酸化物を併用する場合の添加量を限定する理由は下記の通りである。 いずれも１ｗｔ％未満では、強度向上、複合スピネルの生成に寄与せず効果がない。また、金属粉末が１０ｗｔ％超、あるいは酸化物が２０ｗｔ％超になると、れんが中またはスラグ中のＳｉＯ2、ＣａＯと反応して、ＣａＯ−Ａｌ2Ｏ3、ＣａＯ−Ｆｅ2Ｏ3、ＣａＯ−ＭｇＯ−ＳｉＯ2、ＣａＯ−Ａｌ2Ｏ3−Ｆｅ2Ｏ3系などの低融点物の生成量が多くなり耐食性が低下するためである。
【００１７】
また、カーボンを添加する理由は以下の通りである。
すなわち、カーボンは溶鋼やスラグの浸透を防止する。その結果、変質部分が原質部から剥離するのを防止し、いわゆる耐構造的スポーリング性の向上に効果を発揮する。
【００１８】
なお、使用するカーボンの種類については特に限定されない。例えばリン状黒鉛、土状黒鉛、人造黒鉛、ピッチコークス、無煙炭、カーボンブラックなどから選ばれる１種以上が使用可能であるが、高耐食性ということから固定炭素含有量９５ｗｔ％以上のリン状黒鉛を使用するのが好ましい。
【００１９】
カーボンを添加する場合、その添加量は１〜２０ｗｔ％が好ましい。１ｗｔ％未満では添加した効果が無く、２０ｗｔ％超になると、強度低下が大きく、溶鋼による摩耗のため損耗が大きくなるからである。
【００２０】
以上の配合物に、本発明の効果を損なわない範囲において、成形性を良好にするために粘土などの耐火材料を適量、例えば０．５〜５ｗｔ％添加してもよいことは従来の焼成品の製造と同様である。
【００２１】
本発明の不焼成品は上記の配合物を混練、成形、乾燥して製造される。混練、成形、乾燥の方法は通常のれんが製造法と変わりない。
結合剤として例えば、フエノール樹脂、フラン樹脂、リグニンスルフォン酸ソーダ、ワニス、シリコーン、珪酸ソーダ、燐酸アルミニウムなどの有機・無機結合剤を添加し、混練する。
成形は、れんがの用途、所有する製造設備などに合わせて、例えばフリクションプレス、オイルプレス、ラバープレスなどで加圧成形後、例えば１００〜５００℃で乾燥する。
【００２２】
【実施例】
以下、本発明実施例とその比較例を示す。表１は本発明実施例およびその試験結果、表２は本発明実施例と比較例およびその試験結果である。
【００２３】
【表１】
【表２】
各例は、表１、表２に示すマグネシア質原料、クロム鉄鉱、酸化クロム、マグクロクリンカー、アルミナ、チタニア、金属粉末、もしくは酸化物やカーボンを用いた配合組成に結合剤としてフェノール樹脂を外掛けで１．５〜４ｗｔ％添加し、混練後、フリクションプレスにて並型形状に加圧成形した。その後、１２０℃×１６時間乾燥を行い供試れんがとした。
【００２６】
こうして得られた供試れんがを使用し、表１、表２に示す物性、特性を評価した。
試験項目、測定方法は以下の通りである。
【００２７】
見掛比重；通常の耐火物試験法（ＪＩＳ Ｒ２２０５準拠）により見掛気孔率を測定した。
【００２８】
曲げ強さ；前記並形形状の供試れんがから３０×１５×２０ｍｍのテストピースを切り出し、１５００℃に保持した電気炉で加熱した後、３点曲げ試験を行った。
【００２９】
耐熱スポーリング性；供試れんがから５５×５５×２３０ｍｍの角柱状テストピースを切り出し、片面を１４００℃に保持した電気炉中に入れて１５分間保持する。ついで炉外に取り出し１５分間室温で強制空冷する加熱−冷却サイクルによる熱衝撃を２５回を限度に反復した。剥落に至るまでの熱衝撃の回数で評価した。耐熱スポーリング性は剥落に至るまでの熱衝撃の回数の多い方が良好である。なお、２５回反復した時点で剥落しないものは２５＋で表した。
【００３０】
耐食性、耐浸透性；溶損量とスラグ浸透厚さとにより評価した。すなわち、供試れんがから複数の台形柱状のテストピースを切り出し、これらをドラム内に内張りし、ドラムを回転させながらドラムの軸線方向に酸素−プロパン炎を吹き込み１７００℃に加熱した。１７００℃に保ったまま侵食剤として鋼とスラグ（ＣａＯとＳｉＯ2の比が３：１のもの）を６：４の比率となるように投入し、３０分間侵食を行わせた。侵食剤を排出後、加圧空気による強制空冷を２０分間行った。このガス炎による加熱から強制空冷までの操作を５回繰り返した。その後、テストピースを切断し、溶損量、スラグ浸透厚さを各テストピースの各部の平均値で測定した。
なお、表１、表２では比較例１の溶損量を１００とした場合の各例の溶損量を耐食性指数で表わし、スラグ浸透厚さはｍｍで示している。
【００３１】
表２に示す比較例１は従来の焼成品で、現在ＲＨ式真空脱ガス炉に使用されているものである。これに対し実施例１〜１７は比較例１に比べて、いずれも耐熱スポーリング性、耐食性、耐スラグ浸透性が同等以上の結果を示している。
【００３２】
比較例２、３は不焼成品で、アルミナ、チタニアの添加量が本発明の範囲より少ない例と多い例である。比較例２は添加したアルミナ、チタニアの固溶体反応による効果が出ておらず、比較例３は固溶体反応にあずからない未反応のＴｉＯ2がＭｇＯ粒界に多量に分布し、ＭｇＯ粒子の崩壊をもたらし耐食性の低下が著しい。
【００３５】
比較例４、５も不焼成品で、カーボンの添加量が本発明の範囲より少ない例と多い例である。少量ではあるが本発明の範囲内で添加した実施例８に比較して、比較例４は添加量が少ないため添加した効果が出ていない。また、比較例５も本発明の範囲内で添加した実施例８、９、１０に比較して耐食性が劣っているのがわかる。
なお、実施例では金属粉末として金属Ａｌを、カーボンとしてリン状黒鉛を使用したものを挙げたが、添加量が本発明の範囲内であれば、前記した金属粉末やカーボンを使用しても同様の効果が得られた。
【００３６】
実機試験；前記実施例の項で示したのとほぼ同様の方法で実機形状に製造した不焼成品のうち、実施例２、５、１４、１６、比較例１を同時に実際に、２５０ｔＲＨ式真空脱ガス炉の下部槽の内張りに築造後稼働し、比較例１と実施例の残存寸法から損耗速度（ｍｍ／ｃｈ）に基づいて予想耐用ｃｈを求めた。
比較例１の３２０ｃｈに対して、実施例２、５、１４、１６は実機試験においてもそれぞれ、３３３ｃｈ、３４５ｃｈ、３５６ｃｈ、３４１ｃｈと高耐用性を示した。
【００３７】
実機試験における築造部位はＲＨ式真空脱ガス炉の中でも溶鋼の環流による損傷が著しい部位である。この試験結果からも明らかなように、本発明により得られた不焼成品は実機においても十分な効果を発揮した。
実機試験の例としてＲＨ式真空脱ガス炉の下部槽で行われた場合を記載したが、ＤＨ式真空脱ガス炉、ＡＯＤ炉などにおいても同様な効果が得られた。
【００３８】
【発明の効果】
本発明により製造される不焼成品は、アルミナ質原料、チタニア質原料による固溶体反応を利用し、さらに、金属粉末、酸化物、カーボンを適量添加したことにより従来の焼成品と同等以上に耐食性、耐熱スポーリング性に優れ高耐用性である。
また、焼成工程が不要なので、それに係る燃料費、労務費、諸経費が不必要となり製造原価の大幅な削減を果たすばかりでなく、出荷までの日数を５〜６日短縮することができ、その経済的・営業的効果は大きい。[0001]
[Industrial application fields]
The present invention relates to a magnesia-chromium unfired brick excellent in corrosion resistance and heat spalling resistance.
[0002]
[Prior art]
Magnesia brick has a high melting point and is excellent in erosion resistance against basic slag generated during metal refining, and is therefore used in large quantities as a metal refractory lining refractory.
However, in spite of the above-mentioned features, the magnesia brick is inferior in heat spalling resistance and structural spalling resistance, and the container lined with the magnesia brick has a short life. Structural spalling is a phenomenon in which a slag infiltration generates an altered part that is significantly different in structure from the original part, and this altered part peels off from the original part due to a sudden rise or fall in temperature during container use. It is.
[0003]
Therefore, as a measure for preventing such peeling of the magnesia brick, it is considered to use a combination of a magnesia raw material and chromite.
Magnesia-chromic bricks mainly composed of magnesia material and chromite ore are excellent in corrosion resistance and heat spalling properties, and have been conventionally used in steelmaking processes such as molten steel vacuum degassing furnaces such as RH and DH, AOD furnaces, etc. Used as a lining material.
Magnesia-chromic bricks can be broadly divided into direct bond bricks and ribbon bricks based on their raw material composition. The former uses high-purity synthetic magnesia clinker as the magnesia source, and natural chromium iron ore as the chromium source, and is molded by adding an appropriate binder to these blends and fired at a high temperature of 1700 ° C or higher. Manufactured. On the other hand, the latter is obtained by molding in the same manner as the former using a sintered magcrocliner obtained by pre-sintering magnesia clinker and chromite with a rotary kiln or tunnel kiln.
[0004]
Conventionally, material improvement has been actively performed mainly for improving the corrosion resistance of magnesia-chromic brick. For example, Japanese Patent Publication No. 63-31428 uses a high-purity magnesia clinker and chromite with a low silica component, and Japanese Patent Application Laid-Open No. 2-196003 uses a large amount of chromium oxide. A magnesia-chromic brick that has formed a strong picrochromite bond, absorbs thermal shock strain due to the pores and low expansibility of chromium oxide, and satisfies both corrosion resistance and heat spalling resistance has been introduced.
[0005]
[Problems to be solved by the invention]
In recent years, as demand for high-grade steel increases, magnesia-chromic bricks are used in special refining furnaces such as secondary refining furnaces, and severe conditions such as slag and molten steel wear are increasing. Chrome steel bricks do not provide a sufficient life span. Furthermore, recently, for the prevention of adhesion of metal by splash and the production of ultra-low carbon steel, oxygen blowing operation has increased, and further improvement in corrosion resistance is required.
However, on the other hand, there is also a demand for inexpensive magnesia-chromic bricks that are excellent in corrosion resistance and heat spalling resistance as crude steel production decreases.
[0006]
The present invention provides an inexpensive magnesia-chromium non-fired brick (hereinafter referred to as an unfired product) in place of the conventional expensive magnesia-chromium fired brick (hereinafter referred to as a fired product). In addition, the object is to ensure the corrosion resistance and heat spalling resistance equal to or higher than those of conventional fired products, and to improve the durability.
[0007]
[Means for Solving the Problems]
Based on the above-mentioned problems, the present inventors repeated experiments to obtain an inexpensive non-fired product as an alternative to the conventional fired product.
As a result, it is known that the unfired product generates a spinel product in the vicinity of the working surface at a high temperature during use, and further, the corrosion resistance is equal to or higher than that of the fired product by the action of Al 2 O 3 and TiO 2 described later. It was confirmed that the heat spalling property was improved, and the present invention was completed.
The fired product is fired at a high temperature to generate spinel products such as picrochromite to improve corrosion resistance. However, the firing process has an impact on manufacturing costs, and the price has also increased. The non-fired product of the present invention solves this problem.
[0008]
That is, the specific invention of the present application is A magnesia-chromium non-fired brick that is kneaded, molded, and dried with a binder composition containing high-purity magnesia materials, chromia materials, alumina materials, and titania materials as the main ingredients. a is a chemical component of Al 2 O 3 in the blending composition is 2 to 15 wt%, the chemical components of the TiO 2 is characterized in that it is a 2 to 10 wt%.
[0009]
Hereinafter, the present invention will be described in detail.
Specific examples of the magnesia raw material and the alumina raw material that can be used in the present invention may be one or two or more selected from sintered or electrofused products made of natural raw materials or artificial raw materials. The purity does not particularly affect the effect of the present invention, but it is desirable to use a high-purity MgO component and Al 2 O 3 component with a purity of 95% or more, that is, a material with few impurities. The particle size is adjusted to coarse particles, medium particles, and fine particles so that a densely packed structure can be obtained as in the case of conventional fired products.
[0010]
As the chromia-based material, chromite, chromium oxide, and magcro clinker can be used.
Examples of chromite can include Pakistan chromite, Turkish chromite, machine rock chromite, Japanese chromite, transvalle chromite, and the like, and it is desirable to use chromite.
The component of chromite ore reacts with the MgO component of the magnesia raw material during use to form a composite spinel structure, and has a function of firmly bonding the aggregates.
As for chromium oxide, a commercially available product having a purity of 90% or more can be used as in the case of a conventional refractory material. Chromium oxide has an effect of preventing penetration of slag and molten steel, and is considered to be a fine powder of commercially available chromium oxide and is used as a matrix powder.
As for the magcro clinker, an electrofused magcro clinker obtained by electrically melting magnesia clinker and chromite or chromium oxide in an electric furnace, or the sintered magcro clinker described above can be used.
[0011]
The titania material may be a rutile type, anatase type, or a combination thereof. It is desirable to add the alumina raw material or titania raw material as a matrix powder in order to increase the reactivity. When these mixtures are used as unfired products by kneading, molding, and drying, the temperature near the operating surface is high due to the high temperature during use.
[0012]
Hair cracks due to expansion and contraction occur at the boundary between the solid solution and MgO particles, or the solid solution moves to the gap between the aggregate particles and fills the gap, thereby reducing the pore diameter.
That is, heat spalling properties are improved by the occurrence of hair cracks, and the pore diameter is reduced, so that the penetration of slag and molten steel can be prevented and the corrosion resistance is improved. In other words, as a non-fired product, the durability can be improved as compared with a conventional fired product.
[0013]
The chemical components of Al 2 O 3 and TiO 2 are Al 2 O 3 : 2 to 15 wt% and TiO 2 : 2 to 10 wt% in the composition. The reason is as follows. That is, in order to reduce the pore diameter in the solid solution reaction based on the above formulas (1) to (3), the molar ratio of TiO 2 / Al 2 O 3 is desirably 1.0 , and if the TiO 2 is less than 2 wt%, Since the added TiO 2 is mainly distributed in the MgO grain boundary, the effect of TiO 2 cannot be obtained. On the other hand, when TiO 2 exceeds 10 wt%, unreacted TiO 2 that is not involved in the solid solution reaction of the above-mentioned formulas (1) to (3) is distributed in a large amount in the MgO grain boundary, resulting in the decay of MgO particles and corrosion resistance. The chemical composition of TiO 2 is limited to 2 to 10 wt% because it causes a decrease. Therefore, the molar ratio of TiO 2 / Al 2 O 3 is 1.0, and therefore the chemical component of Al 2 O 3 is desirably 2 to 15 wt%.
[0014]
In order to impart strength to the unfired product of the present invention, in order to further improve corrosion resistance and structural spalling resistance, one or more of the following metal powders, or one or more of oxides or carbons may be added in combination. Can do.
Examples of the metal powder include metal Al, metal Mg, metal Si, and Mg—Al alloy, and the addition amount is preferably 1 to 10 wt%.
Examples of the oxide include SiO 2 , ZrO 2 , Fe 2 O 3 and the like, and the addition amount is preferably 1 to 20 wt%.
[0015]
The reason for adding the above metal powder and oxide is as follows.
That is, the metal powder or oxide acts as a sintering aid for imparting strength, and for example, forms a composite spinel represented by the general formula (Fe, Mg) O. (Zr, Fe) 2 O 3. This is because the corrosion resistance is improved.
[0016]
The reason for limiting the amount of addition when the metal powder and oxide are used in combination is as follows. In any case, if it is less than 1 wt%, it does not contribute to the improvement of strength and the formation of composite spinel, and is ineffective. Further, when the metal powder exceeds 10 wt% or the oxide exceeds 20 wt%, it reacts with SiO 2 and CaO in the brick or slag, thereby causing CaO—Al 2 O 3 , CaO—Fe 2 O 3 and CaO—. This is because the amount of low melting point products such as MgO—SiO 2 and CaO—Al 2 O 3 —Fe 2 O 3 is increased and the corrosion resistance is lowered.
[0017]
The reason for adding carbon is as follows.
That is, carbon prevents the penetration of molten steel and slag. As a result, the altered part is prevented from peeling off from the original part, and the effect of improving the so-called structural spalling resistance is exhibited.
[0018]
The type of carbon used is not particularly limited. For example, one or more kinds selected from phosphorus-like graphite, earth-like graphite, artificial graphite, pitch coke, anthracite, carbon black, etc. can be used, but because of high corrosion resistance, phosphorus-like graphite having a fixed carbon content of 95 wt% or more is used. It is preferred to use.
[0019]
When adding carbon, the addition amount is preferably 1 to 20 wt%. If the amount is less than 1 wt%, the added effect is not obtained. If the amount exceeds 20 wt%, the strength is greatly reduced, and wear is increased due to wear by molten steel.
[0020]
It is a conventional fired product that an appropriate amount of a refractory material such as clay, for example, 0.5 to 5 wt%, may be added to the above blend in order to improve moldability within the range not impairing the effects of the present invention. It is the same as that of manufacture.
[0021]
The non-fired product of the present invention is produced by kneading, molding, and drying the above blend. The method of kneading, molding, and drying is the same as that of ordinary brick manufacturing methods.
As a binder, for example, an organic / inorganic binder such as phenol resin, furan resin, sodium lignin sulfonate, varnish, silicone, sodium silicate, and aluminum phosphate is added and kneaded.
The molding is performed at a temperature of, for example, 100 to 500 ° C. after pressure molding using, for example, a friction press, an oil press, a rubber press, or the like in accordance with the use of the brick and the manufacturing equipment owned.
[0022]
【Example】
Examples of the present invention and comparative examples thereof are shown below. Table 1 shows examples of the present invention and test results thereof, and Table 2 shows examples of the present invention, comparative examples and test results thereof.
[0023]
[Table 1]
[Table 2]
In each example, the phenolic resin is added as a binder to the blending composition using the magnesia raw material, chromite, chromium oxide, magcro clinker, alumina, titania, metal powder, or oxide or carbon shown in Tables 1 and 2. 1.5-4 wt% was added by hanging, and after kneading, it was pressure-molded into a normal shape by a friction press. Thereafter, drying was performed at 120 ° C. for 16 hours to obtain a test brick.
[0026]
Using the test bricks thus obtained, the physical properties and characteristics shown in Tables 1 and 2 were evaluated.
Test items and measurement methods are as follows.
[0027]
Apparent specific gravity; Apparent porosity was measured by a normal refractory test method (based on JIS R2205).
[0028]
Bending strength: A test piece of 30 × 15 × 20 mm was cut out from the parallel-shaped test bricks, heated in an electric furnace maintained at 1500 ° C., and then subjected to a three-point bending test.
[0029]
Heat-resistant spalling property: A 55 × 55 × 230 mm prismatic test piece is cut out from the test brick, placed in an electric furnace whose one side is maintained at 1400 ° C., and held for 15 minutes. Subsequently, the thermal shock by the heating-cooling cycle in which the battery was taken out of the furnace and forcedly cooled at room temperature for 15 minutes was repeated up to 25 times. Evaluation was based on the number of thermal shocks until peeling. The heat spalling property is better when the number of thermal shocks until peeling is increased. In addition, the thing which does not peel off at the time of repeating 25 times was represented by 25+.
[0030]
Corrosion resistance, penetration resistance: Evaluation was based on the amount of erosion loss and slag penetration thickness. That is, a plurality of trapezoidal columnar test pieces were cut out from a test brick, and these were lined in a drum, and an oxygen-propane flame was blown in the axial direction of the drum while rotating the drum and heated to 1700 ° C. While maintaining the temperature at 1700 ° C., steel and slag (with a ratio of CaO to SiO 2 of 3: 1) were added as erosion agents at a ratio of 6: 4, and erosion was performed for 30 minutes. After discharging the erodant, forced air cooling with pressurized air was performed for 20 minutes. This operation from heating by gas flame to forced air cooling was repeated 5 times. Then, the test piece was cut | disconnected and the amount of erosion loss and slag penetration thickness were measured by the average value of each part of each test piece.
In Tables 1 and 2, when the amount of erosion in Comparative Example 1 is 100, the amount of erosion in each example is represented by a corrosion resistance index, and the slag penetration thickness is indicated in mm.
[0031]
Comparative Example 1 shown in Table 2 is a conventional fired product that is currently used in an RH vacuum degassing furnace. On the other hand, compared with the comparative example 1, Examples 1-17 have shown the result whose heat spalling property, corrosion resistance, and slag penetration property are equivalent or more.
[0032]
Comparative Examples 2 and 3 are non-fired products, and are examples in which the amounts of alumina and titania added are less and more than the scope of the present invention. Comparative Example 2 has no effect due to the solid solution reaction of the added alumina and titania, and Comparative Example 3 has a large amount of unreacted TiO 2 that is not involved in the solid solution reaction distributed in the MgO grain boundary, causing the MgO particles to collapse. The corrosion resistance is significantly reduced.
[0035]
Comparative examples 4 and 5 are also non-fired products, and are examples in which the amount of carbon added is smaller and larger than the range of the present invention. Although it is a small amount, compared with Example 8 added within the scope of the present invention, Comparative Example 4 does not have the effect of being added because the amount added is small. Moreover, it turns out that the comparative example 5 is also inferior in corrosion resistance compared with Example 8, 9, 10 added within the scope of the present invention.
In the examples, metal Al was used as the metal powder, and phosphorus-like graphite was used as the carbon. However, if the addition amount is within the range of the present invention, the above-mentioned metal powder or carbon is also used. The effect of was obtained.
[0036]
Actual machine test: Among the non-fired products manufactured in the actual machine shape in the same manner as described in the above-mentioned Example section, Examples 2, 5, 14, 16 and Comparative Example 1 were actually used in a 250 tRH vacuum at the same time. After construction on the inner lining of the lower tank of the degassing furnace, the expected service ch was determined based on the wear rate (mm / ch) from the remaining dimensions of Comparative Example 1 and Example.
In comparison with 320 ch of Comparative Example 1, Examples 2, 5, 14, and 16 also showed high durability in the actual machine test as 333 ch, 345 ch, 356 ch, and 341 ch, respectively.
[0037]
In the RH vacuum degassing furnace, the construction site in the actual machine test is a site that is severely damaged by the recirculation of molten steel. As is clear from the test results, the non-fired product obtained by the present invention exhibited a sufficient effect even in an actual machine.
As an example of the actual machine test, the case where the test was performed in the lower tank of the RH type vacuum degassing furnace was described, but the same effect was obtained in the DH type vacuum degassing furnace, the AOD furnace, and the like.
[0038]
【The invention's effect】
The non-fired product produced according to the present invention utilizes a solid solution reaction with an alumina raw material and a titania raw material, and further has a corrosion resistance equal to or higher than that of a conventional fired product by adding an appropriate amount of metal powder, oxide, and carbon. Excellent heat resistance and high durability.
In addition, since the firing process is unnecessary, the fuel cost, labor cost, and other costs associated with it are unnecessary, and not only can the manufacturing cost be greatly reduced, but the number of days until shipment can be shortened by 5 to 6 days. Economic and sales effects are significant.
Claims (5)
前記配合組成中のＡｌ２Ｏ３の化学成分が２〜１５ｗｔ％であり、ＴｉＯ２の化学成分が２〜１０ｗｔ％であるマグネシア−クロム質不焼成れんが。A magnesia-chromium non-fired brick that is kneaded, molded, and dried with a binder composition containing high-purity magnesia material, chromia material, alumina material, and titania material as the main ingredients Because
A magnesia-chromic unfired brick in which the chemical composition of Al 2 O 3 in the blend composition is 2 to 15 wt% and the chemical component of TiO 2 is 2 to 10 wt%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07981694A JP3703104B2 (en) | 1994-03-24 | 1994-03-24 | Magnesia-chromic unfired brick |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07981694A JP3703104B2 (en) | 1994-03-24 | 1994-03-24 | Magnesia-chromic unfired brick |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08143357A JPH08143357A (en) | 1996-06-04 |
| JP3703104B2 true JP3703104B2 (en) | 2005-10-05 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07981694A Expired - Fee Related JP3703104B2 (en) | 1994-03-24 | 1994-03-24 | Magnesia-chromic unfired brick |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3703104B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4681456B2 (en) * | 2006-01-05 | 2011-05-11 | 黒崎播磨株式会社 | Low carbon magnesia carbon brick |
-
1994
- 1994-03-24 JP JP07981694A patent/JP3703104B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08143357A (en) | 1996-06-04 |
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