JP4070033B2 - Unshaped refractory for casting construction and molten steel container lined with this - Google Patents
Unshaped refractory for casting construction and molten steel container lined with this Download PDFInfo
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- JP4070033B2 JP4070033B2 JP08769697A JP8769697A JP4070033B2 JP 4070033 B2 JP4070033 B2 JP 4070033B2 JP 08769697 A JP08769697 A JP 08769697A JP 8769697 A JP8769697 A JP 8769697A JP 4070033 B2 JP4070033 B2 JP 4070033B2
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Description
【0001】
【発明の属する技術分野】
本発明は、流し込み施工用不定形耐火物とこれを内張りした溶鋼容器に関するものである。
【0002】
【従来の技術】
溶鋼取鍋、タンデッシュ、真空脱ガス炉などの溶鋼容器の内張りに使用する流し込み施工用不定形耐火物(以下、流し込み材)として、例えば特開平5−97526号公報あるいは特開平8−2975号公報にアルミナ−マグネシア質が提案されている。
【0003】
この材質は、アルミナおよびマグネシアがもつ耐食性と、アルミナとマグネシアとの反応により生成されるMgO・Al203系スピネル(以下、単にスピネルと称する)の耐スラグ浸透防止の効果が相まって、優れた耐用性が得られる。
【0004】
【発明が解決しようとする課題】
しかし、近年の溶鋼容器の使用条件は、溶鋼温度の上昇、滞湯時間の延長、ガス吹き込み撹拌などにより、苛酷化の一途をたどり、アルミナ−マグネシア質流し込み材といえども十分なものではない。そこで、従来材質よりさらに耐用性に優れた内張り材が強く求められている。
【0005】
アルミナ−マグネシア質の流し込み材において、マグネシアを微粒で配合することでアルミナとの反応性の向上でスピネル生成が顕著となり、耐スラグ浸透性がより効果的ものとなる。また、マグネシア自身は熱膨張係数が大きいが、マグネシアを微粒で配合すると流し込み材としての熱膨張は小さくなり、耐スポーリング性の面でも好ましい。
【0006】
しかし、マグネシアは施工水との反応で消化〔MgO+H2O→Mg(OH)2〕し、この消化に伴う体積膨張で流し込み材の施工体組織がぜい弱化する問題がある。マグネシアは微粒化で前記したように耐スラグ浸透性および耐スポーリング性が向上するが、反面、微粒化は比表面積の増大で消化し易くなり、これが原因で結局は十分な耐用性が得られない。
【0007】
本発明はアルミナ−マグネシア質の流し込み材における上記の問題を解決することを目的とする。
【0008】
【課題を解決するための手段】
本発明は、アルミナ70〜99wt%、マグネシア1〜30wt%を含む粒度10mm未満の耐火骨材100wt%に、外掛け割合で塩基性乳酸アルミニウム0.05〜1.5wt%、熱水溶解性のPVA短繊維0.01〜1wt%およびアルミナセメントを添加し、かつ前記マグネシアの粒度が耐火骨材全体に占める割合で75μm以下が1〜15wt%の耐消化性に優れた流し込み施工不定形耐火物である。
【0009】
不定形耐火物において塩基性質乳酸アルミニウムの添加が消化防止に効果があることは、例えば特開平7−257978号公報において公知である。塩基性質乳酸アルミニウムは、マグネシアの表面をコーティングして消化を防止する。
【0010】
また、塩基性質乳酸アルミニウムは施工水の添加によりゲル化し、そのゲル化に伴う体積収縮で耐火物組織内に微細な亀裂を形成する。そして、流し込み材施工体の加熱乾燥時には、前記の微細な亀裂が施工水から発生する水蒸気の耐火物組織外への逸散を促進し、消化防止を一層効果的なものにしていることが判った。しかし、乳酸アルミニウムのゲル化に伴う収縮の応力が一部の箇所に集中し、大きな亀裂となり、耐用性を低下させる問題がある。
【0011】
一方、PVA短繊維などの有機繊維の添加で流し込み材の乾燥性を高めることが、例えば特開平3−265572号公報などで提案されている。有機繊維は耐火物組織内に水蒸気の逃路を形成し、施工体の膨れや乾燥爆裂を防止する効果をもつ。
【0012】
これに対し本発明は、塩基性質乳酸アルミニウムとPVA短繊維とを特定の割合で添加したことで、その耐用性を格段に向上させたものである。その詳細な機構は不明であるが、次ぎのとおりと考えられる。
【0013】
塩基性質乳酸アルミニウムのゲル化で形成される微細な亀裂は、消化防止の効果を持つ反面、その亀裂が一部に集中して大きな亀裂を発生する。本発明では、PVA短繊維のスサ効果で塩基性質乳酸アルミニウムのゲル化に伴う収縮応力を分散させ、大きな亀裂の発生を防止する。
【0014】
しかも、PVA短繊維は流し込み材の施工時の前記補強に作用した後は、加熱乾燥時の比較的低温域で萎縮後、溶解することで耐火物組織内に空隙を形成し、施工水からの水蒸気の逸散をさらに容易し、消化防止をより確実なものにする。PVA以外の例えばポリプロピレン、ポリエチレンなどの短繊維は、加熱下で萎縮せず、軟化溶融して耐火物組織内の微細な亀裂を閉塞し、水蒸気の逸散が容易でなく、耐消化性に劣るためか耐食性において十分な効果が得られない。
【0015】
PVA短繊維などの有機繊維の添加で施工体の膨れや乾燥爆裂を防止する効果は知られている。PVA短繊維と塩基性質乳酸アルミニウムとの組合せによる本発明での顕著な効果は、施工体の膨れや乾燥爆裂を防止によるものではなく、アルミナ−マグネシア質流し込み材における消化防止が作用していると考えられる。
【0016】
【発明の実施の形態】
アルミナは耐食性と容積安定性とを兼ね備えた耐火原料である。本発明はこのアルミナの割合が70wt%未満では耐スポーリング性に劣り、99wt%を超えると耐スラグ浸透性に劣る。
【0017】
アルミナの種類は焼結品,電融品のいずれでも使用でき、Al2O3純度は90%以上が好ましい。TiO2を1〜8wt%程度あるいはMgOを5〜10wt%程度含有したものを使用できる。また、ばん土けつ岩、シリマナイト、ムライトなどの低純度品を使用してもよいが、微粉部には高純度品を使用するのが好ましい。
【0018】
アルミナの粒度は10mm未満とし、好ましくは8mm以下である。緻密な施工体が得られるように、その粒度は、後述するマグネシアの粒度も考慮して粗粒、中粒、微粒に適宜調整する。微粒には仮焼品を使用してもよい。
【0019】
マグネシアは、アルミナとの反応でスピネル(以下、スピネルと称する)を生成し、このスピネルがスラグ中のFeO、MnOなどの成分を固溶することで耐火物組織内へのスラグ浸透を防止する。また、そのスピネル生成に伴う体積膨張で耐火物組織の緻密化を図ることも、スラグ浸透を防止する効果がある。
【0020】
マグネシアは、焼結品、電融品のいずれでも良く、その割合は、1wt%未満では耐スラグ浸透性の効果に劣り、30wt%を超えると耐スポーリング性に劣る。
【0021】
マグネシアの粒度は10mm未満とし、同時に耐火骨材全体に占める割合で75μm以下が1〜15wt%であることが必要である。75μm以下が1wt%未満では耐スラグ浸透性の効果に劣り、15wt%を超えるとスピネル生成時の体積膨張が過多となって耐スポーリング性に劣る。また、マグネシア全体の割合が30wt%を超えるとマグネシア自身の熱膨張性によって耐スポーリング性が低下する。
【0022】
75μm以下の粒度の調整は、例えばタイラー標準篩200メッシュによって行なうことができる。この75μm以下は耐火骨材全体に占める割合であり、例えば1mm以下の篩下にも一部に75メッシュ以下のものが含まれていれば、それらも加算する。
【0023】
耐火骨材として、さらに、スピネル、炭化珪素、クロム鉱、炭素、揮発シリカなどを組み合わせてもよい。スピネルは比較的多く配合してもよいが、本発明におけるアルミナとマグネシアとの反応によるスピネル生成を阻害しないために、耐火骨材中に占める割合は20wt%以下が好ましい。
【0024】
揮発シリカは、例えばシリコンまたは珪素合金製造の際の副産物として得られれ、シリカフラワーまたはマイクロシリカなどの商品名で市販されている。耐火物組織を緻密化して耐食性を向上させるなどの効果を持つ。耐火骨材中に占める割合は3wt%以下とする。3wt%を超えると低融点物質を生成して耐食性を低下させる。最も好ましい範囲は、0.05〜1.5wt%である。
【0025】
塩基性乳酸アルミニウムはAl2O3/乳酸がモル比で0.3〜2のものが好ましい。その割合は耐火骨材に対する外掛けで0.05wt%未満では耐消化性の効果がなく、1.5wt%を超えると耐食性が低下する。耐火骨材に対する添加は、後述した実施例では粉末状で添加したが、予め水でといて添加してもよい。
【0026】
PVA(ポリビニールアルコール)短繊維は熱水可溶性をもつ。そのサイズは1〜3デニール、長さ1〜10mmのものが好ましい。添加割合は、耐火骨材に対する外掛けで0.01wt%未満では耐消化性の効果に劣り、1wt%を超えると耐食性が低下する。
【0027】
アルミナセメントは結合剤としての役割をもつ。具体的種類および添加割合は従来の流し込み材のものと特に変わりない。好ましい割合は、耐火骨材100%に対して3〜15wt%であり、3wt%未満では十分な施工体強度が得られず、15wt%を超えると耐食性が低下する。
【0028】
その他、流し込み材の添加物として知られている解こう剤、耐火粗大粒子、硬化調整剤、金属短繊維(例えばステンレス鋼ファイバー)、ガラス粉、炭素粉、ピッチ粉、セラミックファイバー、発泡剤などを添加してもよい。。
【0029】
特に解こう剤の添加は施工性の点で有効である。具体例としては、例えばトリポリリン酸ソーダ、ヘキサメタリン酸ソーダ、ウルトラポリリン酸ソーダ、酸性ヘキサメタリン酸ソーダ、ホウ酸ソーダ、炭酸ソーダなどの無機塩、クエン酸ソーダ、酒石酸ソーダ、ポリアクリル酸ソーダ、スルホン酸ソーダなどがある。その添加割合は、耐火骨材100wt%に対する外掛けで0.01〜0.5wt%が好ましい。
【0030】
耐火粗大粒子は、耐火物組織内に発生した亀裂の発達を寸断することで耐スポーリング性の効果をもつ。具体例としてはアルミナ質、スピネル質などである。また、れんが屑、耐火物使用後品などでもよい。粒度は10〜50mmが好ましい。また、その割合は耐火骨材100wt%に対する外掛けで40wt%以下が好ましく、さらに好ましくは5〜30wt%である。40wt%を超えると、その粒度構成のバランスの悪さから施工体の強度が低下し、耐食性の低下を招く。
【0031】
粘土の添加は施工性に有効である。しかし、添加量が多くなると耐食性の低下を招くので、耐火骨材100wt%に対する外掛けで5wt%以下が好ましい。施工は常法どおり、以上の配合組成に外掛けで4〜8wt%程度の施工水を添加・混合し、流し込み施工される。また、流し込み時には一般に振動を付与して充填率を向上させる。
【0032】
【実施例】
表1は実験例、表2は本発明実施例とその比較例である。各例は、表に示した配合物を添加水分外掛け5wt%で混練し、型枠に流し込み施工し、養生後、110℃×24時間で乾燥後したものを試験片とした。試験方法は、以下のとおり。
【0033】
曲げ強さ;実験例では110℃×24時間で乾燥後のもの、使用時の加熱乾燥を想定した500℃×3時間加熱後のもの、溶鋼との接触を想定した1500℃×3時間加熱後のものについて試験した。
【0034】
耐食性;重量比で鋼片:転炉スラグ(FeO含有量;20wt%)=70:30を侵食剤とし、1650℃×5時間の回転侵食試験を行い、溶損寸法を測定した。
【0035】
耐スラグ浸透性;前記の条件で回転侵食試験を行った後、スラグ浸透寸法を測定した。
耐スポーリング性;1550℃×15分加熱後、空冷し、これを5回くり返し、亀裂発生の状況を観察した。
【0036】
実機試験;200トン溶鋼取鍋に中子を用いて流し込み施工し、養生後、使用前に約1000℃で加熱乾燥後、使用し、溶損速度を(mm/チャージ)で測定した。
【0037】
【表1】
【0038】
表1は、塩基性乳酸アルミニウムを添加したアルミナ−マグネシア質流し込み材またはアルミナ−スピネル質流し込み材において、耐火性骨材の種類および割合を一定にし、短繊維の有無と短繊維の種類を変化させたものである。
【0039】
実験例1〜4はアルミナ−マグネシア質流し込み材であり、実験例5〜8はアルミナ−スピネル質流し込み材である。消化による施工体の強度劣化の程度を曲げ強さで測定した。アルミナ−マグネシア質においては、PVA短繊維と塩基性乳酸アルミニウムとを併用添加した実験例2が曲げ強さが大きく、消化性に優れていることが確認された。これに対しアルミナ−スピネル質は、消化しないためか曲げ強さに大きな変化は見られない。
【0040】
【表2】
【0041】
実施例1〜5はいずれも曲げ強さが大きく、アルミナ−マグネシア質流し込み材がもつ耐スラグ浸透性とも相まって、耐食性に優れている。また、この効果は実機試験の耐用性において確認される。
【0042】
PVA短繊維、塩基性乳酸アルミニウム共に添加しない比較例1、PVA短繊維を添加しない比較例2、塩基性乳酸アルミニウムを添加しない比較例6は、耐消化性に劣るために曲げ強さが小さく、耐食性にも劣る。塩基性乳酸アルミニウムの添加量が多すぎる比較例4とPVA短繊維の添加量が多すぎる比較例5は、アルミナ−マグネシア質流し込材がもつ耐スラグ浸透性の効果が発揮されない。
【0043】
実機試験は溶鋼取鍋の内張りにおいて行なったが、本発明の流し込み材はこれに限らず、溶鋼と接するタンデッシュ、真空脱ガス炉、転炉、電気炉などの内張りにも使用することができる。
【0044】
【発明の効果】
このように、本発明において、PVA短繊維と塩基性乳酸アルミニウムとの組み合わせによる消化防止からもたらされる耐用性の向上は、以上の実施例の試験結果からも明らかなようにきわめて顕著である。そして本発明によるアルミナーマグネシア質流し込み材により、溶鋼容器の稼働率を向上させることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an irregular refractory material for casting construction and a molten steel container lined with the refractory material.
[0002]
[Prior art]
As an unshaped refractory for casting construction (hereinafter referred to as casting material) used for lining of molten steel containers such as a ladle, tundish, vacuum degassing furnace, etc., for example, Japanese Patent Laid-Open No. 5-97526 or Japanese Patent Laid-Open No. 8-2975. Alumina-magnesia has been proposed.
[0003]
This material has a corrosion resistance with alumina and magnesia, alumina and MgO · Al 2 0 3 spinel formed by the reaction of a magnesia (hereinafter, simply referred to as spinel) the effect of preventing resistance to slag penetration coupled with excellent Durability is obtained.
[0004]
[Problems to be solved by the invention]
However, the conditions of use of molten steel containers in recent years have continued to become harsh due to the rise of molten steel temperature, the extension of molten metal time, gas blowing and stirring, etc., and even an alumina-magnesia casting material is not sufficient. Therefore, there is a strong demand for a lining material that is more durable than conventional materials.
[0005]
In the casting material of alumina-magnesia, by adding magnesia in fine particles, spinel formation becomes remarkable due to improved reactivity with alumina, and slag penetration resistance becomes more effective. Further, magnesia itself has a large coefficient of thermal expansion, but when magnesia is blended in fine particles, thermal expansion as a casting material is reduced, which is preferable in terms of spalling resistance.
[0006]
However, magnesia is digested by reaction with construction water [MgO + H 2 O → Mg (OH) 2 ], and there is a problem that the construction body structure of the casting material is weakened by volume expansion accompanying this digestion. As described above, magnesia improves slag penetration resistance and spalling resistance as mentioned above, but on the other hand, atomization becomes easier to digest due to an increase in specific surface area, which eventually leads to sufficient durability. Absent.
[0007]
The object of the present invention is to solve the above-mentioned problems in the casting material of alumina-magnesia.
[0008]
[Means for Solving the Problems]
The present invention is based on refractory aggregate 100 wt% containing 70 to 99 wt% alumina and 1 to 30 wt% magnesia and having a particle size of less than 10 mm. Cast-in-place refractory material having excellent digestion resistance, in which 0.01 to 1 wt% of PVA short fibers and alumina cement are added, and the magnesia particle size accounts for 1 to 15 wt% in a ratio of 75 μm or less to the entire refractory aggregate It is.
[0009]
For example, Japanese Patent Application Laid-Open No. 7-257978 discloses that the addition of basic aluminum lactate to an amorphous refractory is effective in preventing digestion. The basic aluminum lactate coats the surface of magnesia to prevent digestion.
[0010]
In addition, the basic property aluminum lactate is gelled by the addition of construction water, and a fine crack is formed in the refractory structure due to volume shrinkage accompanying the gelation. And when heating and drying the casting material construction body, it was found that the fine cracks promoted the diffusion of water vapor generated from the construction water to the outside of the refractory structure, making digestion prevention more effective. It was. However, there is a problem that the shrinkage stress accompanying the gelation of aluminum lactate concentrates on a part of the aluminum lactate, resulting in a large crack and a decrease in durability.
[0011]
On the other hand, for example, Japanese Patent Application Laid-Open No. 3-265572 proposes to increase the drying property of the casting material by adding organic fibers such as PVA short fibers. The organic fiber forms a water vapor escape path in the refractory structure, and has an effect of preventing the construction body from being swollen and dry explosion.
[0012]
In contrast, in the present invention, the basic properties of aluminum lactate and PVA short fibers are added at a specific ratio, so that the durability is remarkably improved. Although the detailed mechanism is unknown, it is considered as follows.
[0013]
The fine cracks formed by the gelation of the basic property aluminum lactate have the effect of preventing digestion, but the cracks concentrate on a part and generate large cracks. In the present invention, the shrinkage effect associated with the gelation of the basic property aluminum lactate is dispersed by the Susa effect of the PVA short fibers, thereby preventing the occurrence of large cracks.
[0014]
In addition, after the PVA short fibers acted on the reinforcement during the construction of the casting material, after shrinking in a relatively low temperature region during heating and drying, a void was formed in the refractory structure by dissolution, and from the construction water Further facilitates the dissipation of water vapor and more reliably prevents digestion. Short fibers other than PVA, such as polypropylene and polyethylene, do not shrink under heating, soften and melt, block fine cracks in the refractory structure, do not easily dissipate water vapor, and have poor digestion resistance. Therefore, sufficient effect cannot be obtained in corrosion resistance.
[0015]
The effect of preventing the swelling and dry explosion of the construction body by adding organic fibers such as PVA short fibers is known. The remarkable effect in the present invention by the combination of the short PVA fiber and the basic property aluminum lactate is not due to prevention of swelling and dry explosion of the construction body, but digestion prevention in the alumina-magnesia casting material is acting. Conceivable.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Alumina is a refractory raw material that has both corrosion resistance and volume stability. In the present invention, when the alumina ratio is less than 70 wt%, the spalling resistance is poor, and when it exceeds 99 wt%, the slag penetration resistance is poor.
[0017]
As the kind of alumina, either a sintered product or an electromelted product can be used, and the purity of Al 2 O 3 is preferably 90% or more. One containing about 1 to 8 wt% of TiO 2 or about 5 to 10 wt% of MgO can be used. Moreover, although low-purity products such as sandstone shale, sillimanite, and mullite may be used, it is preferable to use high-purity products for the fine powder portion.
[0018]
The particle size of alumina is less than 10 mm, preferably 8 mm or less. In order to obtain a dense construction body, the particle size is appropriately adjusted to coarse particles, medium particles, and fine particles in consideration of the magnesia particle size described later. A calcined product may be used for the fine particles.
[0019]
Magnesia produces spinel (hereinafter referred to as spinel) by reaction with alumina, and this spinel dissolves components such as FeO and MnO in the slag, thereby preventing slag penetration into the refractory structure. Further, densification of the refractory structure by volume expansion accompanying the spinel generation also has an effect of preventing slag infiltration.
[0020]
Magnesia may be either a sintered product or an electromelted product, and the proportion is inferior in the effect of slag penetration resistance if it is less than 1 wt%, and inferior in spalling resistance if it exceeds 30 wt%.
[0021]
The particle size of magnesia is less than 10 mm, and at the same time, it is necessary that 75 μm or less is 1 to 15 wt% in the ratio of the entire refractory aggregate. When 75 μm or less is less than 1 wt%, the effect of slag penetration resistance is inferior, and when it exceeds 15 wt%, volume expansion at the time of spinel formation is excessive and the spalling resistance is inferior. Moreover, when the ratio of the whole magnesia exceeds 30 wt%, spalling resistance will fall by the thermal expansion property of magnesia itself.
[0022]
Adjustment of the particle size of 75 μm or less can be performed, for example, with a Tyler standard sieve 200 mesh. This 75 μm or less is the proportion of the entire refractory aggregate. For example, if a part of the sieve under 1 mm or less contains 75 mesh or less, they are also added.
[0023]
As the refractory aggregate, spinel, silicon carbide, chromium ore, carbon, volatile silica and the like may be further combined. A relatively large amount of spinel may be blended, but in order not to inhibit the formation of spinel by the reaction between alumina and magnesia in the present invention, the proportion in the refractory aggregate is preferably 20 wt% or less.
[0024]
Volatile silica is obtained, for example, as a by-product in the production of silicon or silicon alloys and is commercially available under trade names such as silica flour or microsilica. It has the effect of improving the corrosion resistance by densifying the refractory structure. The proportion of the refractory aggregate is 3 wt% or less. If it exceeds 3 wt%, a low-melting-point substance is generated and the corrosion resistance is lowered. The most preferred range is 0.05 to 1.5 wt%.
[0025]
The basic aluminum lactate preferably has an Al 2 O 3 / lactic acid molar ratio of 0.3-2. If the ratio is less than 0.05 wt% as an outer coating with respect to the refractory aggregate, there is no effect of digestion resistance, and if it exceeds 1.5 wt%, the corrosion resistance decreases. Addition to the refractory aggregate was added in powder form in the examples described later, but it may be added in advance with water.
[0026]
PVA (polyvinyl alcohol) short fibers have hot water solubility. The size is preferably 1 to 3 denier and 1 to 10 mm long. If the ratio of addition is less than 0.01 wt% as an outer coating with respect to the refractory aggregate, the effect of digestion resistance is inferior, and if it exceeds 1 wt%, the corrosion resistance decreases.
[0027]
Alumina cement serves as a binder. Specific types and addition ratios are not particularly different from those of conventional casting materials. A preferable ratio is 3 to 15 wt% with respect to 100% of the refractory aggregate, and if it is less than 3 wt%, sufficient construction body strength cannot be obtained, and if it exceeds 15 wt%, the corrosion resistance decreases.
[0028]
In addition, peptizers, refractory coarse particles, hardening modifiers, short metal fibers (for example, stainless steel fibers), glass powder, carbon powder, pitch powder, ceramic fibers, foaming agents, etc., known as additives for casting materials It may be added. .
[0029]
In particular, the addition of a peptizer is effective in terms of workability. Specific examples include, for example, inorganic salts such as sodium tripolyphosphate, sodium hexametaphosphate, sodium ultrapolyphosphate, acid hexametaphosphate, sodium borate, sodium carbonate, sodium citrate, sodium tartrate, sodium polyacrylate, sodium sulfonate and so on. The addition ratio is preferably 0.01 to 0.5 wt% as an outer shell with respect to 100 wt% of the refractory aggregate.
[0030]
Coarse refractory particles have a spalling resistance effect by cutting off the development of cracks generated in the refractory structure. Specific examples include alumina and spinel. Also, brick scraps, refractory-use products, etc. may be used. The particle size is preferably 10 to 50 mm. Moreover, the ratio is preferably 40 wt% or less, more preferably 5 to 30 wt%, as an outer shell with respect to 100 wt% of the refractory aggregate. When it exceeds 40 wt%, the strength of the construction body is lowered due to the poor balance of the particle size constitution, and the corrosion resistance is lowered.
[0031]
Addition of clay is effective for workability. However, since the corrosion resistance decreases when the added amount increases, it is preferably 5 wt% or less as an outer shell with respect to 100 wt% of the refractory aggregate. The construction is carried out by adding and mixing about 4 to 8 wt% of construction water as an outer coating to the above composition and pouring construction. In addition, vibration is generally applied during pouring to improve the filling rate.
[0032]
【Example】
Table 1 shows experimental examples, and Table 2 shows examples of the present invention and comparative examples thereof. In each example, the compound shown in the table was kneaded with 5 wt% of added moisture, poured into a mold, applied, and dried at 110 ° C. for 24 hours after curing. The test method is as follows.
[0033]
Bending strength; in experiment example, dried at 110 ° C. for 24 hours, after heating at 500 ° C. for 3 hours assuming heat drying during use, after heating at 1500 ° C. for 3 hours assuming contact with molten steel Were tested.
[0034]
Corrosion resistance: Steel slab: converter slag (FeO content; 20 wt%) = 70:30 as an erodant by weight ratio. A rotary erosion test at 1650 ° C. × 5 hours was performed to measure the erosion dimension.
[0035]
Resistance to slag penetration; after performing a rotary erosion test under the above conditions, the slag penetration dimension was measured.
Spalling resistance; after heating at 1550 ° C. for 15 minutes, air cooling was repeated 5 times, and the occurrence of cracks was observed.
[0036]
Practical machine test: Casting into a 200-ton molten steel ladle using a core, curing, heating and drying at about 1000 ° C. before use, and measuring the melting rate (mm / charge).
[0037]
[Table 1]
[0038]
Table 1 shows that in the alumina-magnesia cast material or alumina-spinel cast material added with basic aluminum lactate, the kind and ratio of the refractory aggregate is made constant, and the presence or absence of short fibers and the kind of short fibers are changed. It is a thing.
[0039]
Experimental Examples 1 to 4 are alumina-magnesia casting materials, and Experimental Examples 5 to 8 are alumina-spinel casting materials. The degree of strength deterioration of the construction body due to digestion was measured by bending strength. In alumina-magnesia, it was confirmed that Experimental Example 2 in which PVA short fibers and basic aluminum lactate were added in combination had a high bending strength and was excellent in digestibility. In contrast, alumina-spinel is not digested, so there is no significant change in bending strength.
[0040]
[Table 2]
[0041]
Each of Examples 1 to 5 has a high bending strength and is excellent in corrosion resistance in combination with the slag penetration resistance of the alumina-magnesia casting material. This effect is also confirmed in the durability of the actual machine test.
[0042]
Comparative Example 1 in which both PVA short fiber and basic aluminum lactate are not added, Comparative Example 2 in which PVA short fiber is not added, and Comparative Example 6 in which basic aluminum lactate is not added have low bending strength due to poor digestion resistance. Inferior to corrosion resistance. In Comparative Example 4 in which the amount of basic aluminum lactate added is too large and Comparative Example 5 in which the amount of PVA short fibers added is too large, the slag penetration resistance effect of the alumina-magnesia casting material is not exhibited.
[0043]
Although the actual machine test was performed on the lining of the molten steel ladle, the casting material of the present invention is not limited to this, and can also be used for the lining of a tundish, a vacuum degassing furnace, a converter, an electric furnace, etc. in contact with the molten steel.
[0044]
【The invention's effect】
Thus, in the present invention, the improvement in durability resulting from the prevention of digestion by the combination of PVA short fibers and basic aluminum lactate is extremely remarkable as is apparent from the test results of the above examples. And the operation rate of a molten steel container can be improved with the alumina magnesia pouring material by this invention.
Claims (2)
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JP08769697A JP4070033B2 (en) | 1997-03-22 | 1997-03-22 | Unshaped refractory for casting construction and molten steel container lined with this |
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JP08769697A JP4070033B2 (en) | 1997-03-22 | 1997-03-22 | Unshaped refractory for casting construction and molten steel container lined with this |
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JPH10265275A JPH10265275A (en) | 1998-10-06 |
JP4070033B2 true JP4070033B2 (en) | 2008-04-02 |
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