JP2013249245A - Method for recycling used carbon-containing unfired brick - Google Patents

Method for recycling used carbon-containing unfired brick Download PDF

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JP2013249245A
JP2013249245A JP2012138224A JP2012138224A JP2013249245A JP 2013249245 A JP2013249245 A JP 2013249245A JP 2012138224 A JP2012138224 A JP 2012138224A JP 2012138224 A JP2012138224 A JP 2012138224A JP 2013249245 A JP2013249245 A JP 2013249245A
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brick
mgo
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magnesia
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JP5663121B2 (en
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Naonori Nishimura
尚之 西村
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OSAKA YOGYO FIRE BRICK
Yotai Refractories Co Ltd
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OSAKA YOGYO FIRE BRICK
Yotai Refractories Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide reclaimed brick having performance equal to or better than brick using virgin materials by reclaiming used carbon-containing unfired brick, to increase the recycling quantity of used unfired brick than before, and to reduce the scrap disposal volume.SOLUTION: Reclaimed brick is produced using a carburized material obtained by crushing used carbon-containing unfired brick and firing the crushed brick at oxygen concentration of 5.0-9.0% and a temperature of 800-1,000°C.

Description

本発明は、製鋼工場などで発生するカーボン含有不焼成れんが廃耐火物の再利用の方法に関するものである。  The present invention relates to a method of reusing waste refractory carbon-containing unfired brick generated in a steel factory or the like.

製鋼工場の転炉、AOD炉、RH炉、電気炉、取鍋等の内張り用耐火物として、MgO−Cれんが、Al−MgO−Cれんが、Al−Cれんが、MgOれんが、MgO−Crれんが等の各種耐火れんがが使用されている。BOF steelmaking plant, AOD furnace, RH furnace, an electric furnace, a lining refractories ladle etc., MgO-C bricks, Al 2 O 3 -MgO-C bricks, Al 2 O 3 -C bricks, MgO bricks Various refractory bricks such as MgO—Cr 2 O 3 brick are used.

以下、カーボン含有不焼成れんがの代表としてMgO−Cれんがについて述べる。MgO−Cれんがは、マグネシアのもつ高耐食性と、カーボンのもつスラグに濡れにくい性質、及び高熱伝導性という特長により、優れた耐食性と耐スポール性を兼ね備えており、製鋼用内張り材として広く使用されている。  Hereinafter, MgO—C brick will be described as a representative of carbon-containing unfired brick. MgO-C bricks have excellent corrosion resistance and spall resistance due to the high corrosion resistance of magnesia, the property of carbon that does not easily get wet with slag, and high thermal conductivity, and are widely used as lining materials for steelmaking. ing.

このMgO−Cれんがに使用される原料は、マグネシア源として電融マグネシア、海水マグネシア等が、カーボン源として、鱗状黒鉛、土状黒鉛等が一般的に使用されている。マグネシア原料は、耐食性が求められるため、マグネシア含有量が95質量%以上のものが使用されている。  As raw materials used for this MgO-C brick, electrofused magnesia, seawater magnesia and the like are generally used as a magnesia source, and scaly graphite, earthy graphite and the like are generally used as a carbon source. Since the magnesia raw material is required to have corrosion resistance, the magnesia content is 95% by mass or more.

MgO−Cれんがは、製鋼用内張り炉材として一定期間使用された後、新品に取り替えられる。その際に、多量の使用済みMgO−Cれんがが発生する。使用済みれんがは、操業中に発生する不純物を、主に稼働面側に含んでいるので、そのままMgO−Cれんがとして再利用した場合、同等の性能が得られないので、れんがでのリサイクルはあまり進んでいなかった。  The MgO-C brick is used for a certain period of time as a steelmaking lining furnace material, and then replaced with a new one. At that time, a large amount of used MgO-C brick is generated. Spent bricks contain impurities generated during operation mainly on the operating surface side, so when recycled as MgO-C bricks as they are, equivalent performance cannot be obtained, so recycling with bricks is not much It was not progressing.

そのため、使用済みMgO−Cれんがをリサイクルする場合、多くは再粉砕して造滓材に使用したり、整粒して不定形補修材として使用している程度であり、多くは処分場で埋設処理されている。しかも、埋設処分に多大の費用がかかるので、更なるリサイクル量の拡大が課題となっている。  For this reason, when recycling used MgO-C bricks, many are reground and used for slagging materials, or are sized and used as irregular repair materials, and many are buried at disposal sites. Has been processed. In addition, since a large amount of money is required for burying disposal, further expansion of the amount of recycling has been an issue.

これに対し、例えば、以下のようなリサイクル方法が提案されている。特許文献1では、使用後MgO−Cれんがの稼働面側の変質層を除去し、その残部を粉砕して得たリサイクル原料をMgO−Cれんがに添加する方法が開示されている。  On the other hand, for example, the following recycling methods have been proposed. Patent Document 1 discloses a method of removing a deteriorated layer on the working surface side of MgO-C brick after use and adding a recycled material obtained by pulverizing the remainder to MgO-C brick.

しかしながら、特許文献1に開示された方法によるリサイクルれんがは、MgO−Cれんが中の有機結合材や金属粉などの異種原料を含んだ混合状態で再使用するものであり、添加金属の酸化物などが混入した不純物の多い状態でしか回収することができなかったので、バージン原料を使用したれんがの特性を超えるものではなかった。  However, the recycled brick by the method disclosed in Patent Document 1 is to be reused in a mixed state containing different raw materials such as an organic binder and metal powder in the MgO-C brick. Since it could only be recovered in a state with a large amount of impurities mixed in, it did not exceed the characteristics of bricks using virgin raw materials.

特開平8−319154号公報  JP-A-8-319154

本発明は、使用済みMgO−Cれんがを再生し、バージン原料を使用したMgO−Cれんが以上の特性を有するMgO−Cれんがを得ることを目的とする。  An object of the present invention is to regenerate used MgO-C bricks and obtain MgO-C bricks having the above characteristics using MgO-C bricks using virgin raw materials.

本発明は、使用済みMgO−Cれんがを粉砕、整粒、焼成処理して、マグネシアとカーボンを酸化分離する再生工程と、前記再生工程により得た原料を使用して定形耐火物を製造することを特徴とする。  The present invention includes a regeneration step in which used MgO-C brick is pulverized, sized and fired to oxidize and separate magnesia and carbon, and a shaped refractory is produced using raw materials obtained in the regeneration step. It is characterized by.

本発明者は、上記の課題を解決するために鋭意研究を重ねた結果、使用済みMgO−Cれんがを10mm以下に粉砕し、酸化焼成処理を行うことにより、カーボンとマグネシアを分離し、不純物が少なく、新規で優れた特性を有する再生マグネシア原料を得る事ができることを見出した。  As a result of intensive research to solve the above problems, the present inventor separated carbon and magnesia by pulverizing used MgO-C bricks to 10 mm or less and performing an oxidation firing treatment, and impurities were It has been found that a regenerated magnesia raw material having few and excellent characteristics can be obtained.

前記再生マグネシア原料は、使用済みMgO−Cれんがを粗砕し、10mm以下に篩分けしたものを酸化焼成処理することによって得られる。使用済みMgO−Cれんがからカーボンを部分的に分離除去して得られるものである。本発明に基づく処理により、マグネシアにカーボンが0.5〜7.0質量%浸炭した原料(以下浸炭マグネシア原料)が得られるので、特許文献1で開示された再使用方法とは異なるものである。  The recycled magnesia raw material is obtained by subjecting used MgO-C bricks to coarse crushing and sieving to 10 mm or less by oxidation baking treatment. It is obtained by partially separating and removing carbon from used MgO-C brick. By the treatment based on the present invention, a raw material (hereinafter referred to as a carburized magnesia raw material) obtained by carburizing magnesia with 0.5 to 7.0% by mass of carbon is obtained. .

マグネシアに浸炭したカーボンは、製鋼設備操業中の高温操業にさらされ、マグネシア原料中にカーボンが浸炭したものであって、浸炭量は0.5〜7.0質量%程度変動する。浸炭量は再生処理した原料のクリンカー部のみの分析値であり、フリーのカーボンは含まない。  Carbon carburized in magnesia is exposed to high-temperature operation during operation of steelmaking facilities, and carbon is carburized in magnesia raw material. The amount of carburization varies by about 0.5 to 7.0% by mass. The amount of carburization is an analysis value of only the clinker portion of the recycled raw material, and does not include free carbon.

本発明による作用は以下のとおりである。MgO−Cれんがは高耐食性であり、耐スラグ浸透性に優れることで知られているが、カーボンの酸化が最大のネックとされている。そのため、酸化防止剤としてAl、Siなどの金属粉が添加される。本発明の浸炭マグネシア原料を使用したMgO−Cれんがは、カーボンがマグネシア中に浸炭状態で存在するため、酸化が起こりにくく、なおかつ、同量のカーボン量のMgO−Cれんがと比較すると、鱗状黒鉛の添加量を減せるため、従来のMgO−Cれんがより耐酸化性に優れ、低熱伝導性のものとなる。  The operation according to the present invention is as follows. MgO-C brick is known for its high corrosion resistance and excellent slag penetration resistance, but the oxidation of carbon is considered the biggest bottleneck. Therefore, metal powders such as Al and Si are added as an antioxidant. The MgO-C brick using the carburized magnesia raw material of the present invention is less susceptible to oxidation because carbon is present in the carburized state in magnesia, and moreover, compared to MgO-C brick with the same amount of carbon, scaly graphite Therefore, the conventional MgO-C brick has better oxidation resistance and low thermal conductivity.

また使用済みMgO−Cれんがは、製鋼用内張り材として使用される間に繰り返しの熱履歴を受けているため、従来からMgO−Cれんがに使用されている電融マグネシア原料等と比較すると、気孔率が高くなっている。この事から、本発明の浸炭マグネシア原料を使用したMgO−Cれんがは、同量のカーボン量のMgO−Cれんがと比較し、熱伝導率が低くく、耐熱スポーリング性にも優れたものになる。  In addition, since used MgO-C bricks are subjected to repeated thermal history while being used as a steelmaking lining material, compared with the electrofused magnesia raw materials conventionally used for MgO-C bricks, The rate is high. From this, the MgO-C brick using the carburized magnesia raw material of the present invention has a low thermal conductivity and excellent heat resistance spalling property compared to the MgO-C brick of the same amount of carbon. Become.

本発明による浸炭マグネシア原料を使用したMgO−Cれんがは、使用済みMgO−Cれんがを原料として使用するので、リサイクルの幅が広がり、埋設処理量を低減できる。また、低熱伝導性のMgO−Cれんがを提供できるので、製鋼設備の熱ロスを減少しエネルギーコスト低減に寄与する。また、同量のカーボン含量のMgO−Cれんがを製造するのに、鱗状黒鉛の使用量を減らせるため、コスト低減に繋がる。
上記のことは、Al−MgO−Cれんが及びAl−Cれんがについても同様のことが言える。
Since the MgO-C brick using the carburized magnesia raw material according to the present invention uses the used MgO-C brick as a raw material, the range of recycling is widened and the amount of burying treatment can be reduced. Moreover, since the low heat conductive MgO-C brick can be provided, the heat loss of the steelmaking equipment is reduced, and the energy cost is reduced. Moreover, since the usage-amount of scaly graphite can be reduced when manufacturing the MgO-C brick of the same amount of carbon, it leads to a cost reduction.
The same can be said for Al 2 O 3 —MgO—C brick and Al 2 O 3 —C brick.

使用済みMgO−Cれんが原料の粉砕粒度が10mm以下の場合の、処理温度と浸炭マグネシア原料のカーボン量の関係をロータリーキルン内の酸素濃度をパラメーターとして示したグラフである。It is the graph which showed the oxygen concentration in a rotary kiln as a parameter about the relationship between the processing temperature and the carbon amount of a carburized magnesia raw material when the grind | pulverization particle size of a used MgO-C brick raw material is 10 mm or less. マグネシア原料の微構造を示すSEM写真である。図2(a)は本発明により得た浸炭マグネシア原料、図2(b)は未処理使用済みMgO−Cれんがである。It is a SEM photograph which shows the microstructure of a magnesia raw material. FIG. 2 (a) is a carburized magnesia raw material obtained according to the present invention, and FIG. 2 (b) is an untreated used MgO-C brick.

使用済みMgO−Cれんがをマグネシア源として再使用する場合、粉砕・整粒だけでは、異種原料が混ざった混合状態である。加熱酸化処理により、フリーのカーボン及び不純物を除去し、純度の高い浸炭マグネシア原料を得ることができることに着目した。  When the used MgO-C brick is reused as a magnesia source, it is in a mixed state in which different kinds of raw materials are mixed only by crushing and sizing. We focused on the fact that free carbon and impurities can be removed by heat oxidation treatment to obtain a carburized magnesia raw material with high purity.

まず、使用済みMgO−Cれんがから浸炭マグネシア原料を得る再生工程について述べる。  First, a regeneration process for obtaining a carburized magnesia raw material from used MgO-C brick will be described.

使用済みMgO−Cれんがは、転炉使用後品を入手し使用した。前処理として使用済みMgO−Cれんがの選別作業を行った。入手した使用後MgO−Cれんがの多くは、裏張りに使用されているマグネシアれんがや不定形耐火物などのMgO−Cれんが以外のものが含まれているからである。  Used MgO-C bricks were obtained after using the converter. As a pretreatment, sorting of used MgO-C bricks was performed. This is because most of the obtained post-use MgO-C bricks contain things other than MgO-C bricks such as magnesia bricks and amorphous refractories used for the backing.

使用済みMgO−Cれんがは稼働面側の付着物を除去した後、ジョークラッシャー、ロールクラッシャー等で粗粉砕し、粒度10mm以下に整粒したものを焼成処理する。なお、細かい粒子が含まれていても構わない。粒度が10mm以上である場合、原料内部のカーボンが残留しやすく、酸化焼成処理がうまくゆかない。再生後、MgO−Cれんがに再生使用する観点から、5mm以下で焼成処理するほうがより好ましい。  After the used MgO-C brick is removed of deposits on the working surface side, it is coarsely pulverized with a jaw crusher, a roll crusher or the like, and sized to a particle size of 10 mm or less, and then fired. Fine particles may be included. When the particle size is 10 mm or more, the carbon inside the raw material tends to remain, and the oxidation baking treatment does not work well. From the viewpoint of recycling and using the MgO-C brick after regeneration, it is more preferable to perform a baking treatment at 5 mm or less.

本発明に適用する使用済みMgO−Cれんがは通常、転炉、製鋼用電気炉、取鍋等で使用されたものであれば、特に限定されるものではない。使用済みMgO−Cれんが中のMgO含有量及び炭素含有量が変動しても分別や限定の必要はない。酸素濃度、処理温度、投入量、滞留時間等をコントロールすることにより対処可能だからである。  The used MgO-C brick applied to the present invention is not particularly limited as long as it is usually used in a converter, an electric furnace for steel making, a ladle or the like. Even if the MgO content and the carbon content in the used MgO-C brick vary, there is no need for separation or limitation. This is because it can be dealt with by controlling the oxygen concentration, processing temperature, input amount, residence time, and the like.

焼成過程で使用する設備は、単独窯、シャトルキルン、電気炉、ロータリーキルン等が使用できるが、燃費や焼成過程での酸化工程、大量処理できることを考慮すると、ロータリーキルンを使用することが望ましい。
ロータリーキルンの焼成帯温度は800〜1000℃の範囲である事が望ましい。温度が低すぎると粒度、炉内酸素濃度を調整していても酸化焼成がうまく進まない。温度が高すぎると燃費低下につながり不経済である。
As the equipment used in the firing process, a single kiln, shuttle kiln, electric furnace, rotary kiln or the like can be used. However, it is desirable to use a rotary kiln in consideration of fuel consumption, oxidation process in firing process, and mass treatment.
The firing zone temperature of the rotary kiln is desirably in the range of 800 to 1000 ° C. If the temperature is too low, oxidation firing does not proceed well even if the particle size and oxygen concentration in the furnace are adjusted. If the temperature is too high, fuel consumption will be reduced and it will be uneconomical.

酸化焼成に使用するロータリーキルン設備の運転例を述べる。  An example of operation of a rotary kiln facility used for oxidation firing will be described.

ロータリーキルンは内径1m、全長5m程度のものを用意し、キルンの内径が600mmとなる様、内部に不定形耐火物をライニングするとともにキルン内部に撹拌用リフターを設置する。撹拌用のリフターを取り付ける事により効果的に酸化焼成が進む。  A rotary kiln having an inner diameter of 1 m and a total length of about 5 m is prepared. An amorphous refractory is lined inside the kiln so that the inner diameter of the kiln is 600 mm, and a stirring lifter is installed inside the kiln. Oxidation firing proceeds effectively by attaching a lifter for stirring.

ロータリーキルンの窯尻側には集塵機を設置する。熱風炉で発生した熱を窯尻側に引き、酸化可能な焼成帯温度域800〜1000℃の有効距離を延ばすと同時に、酸化焼成によりカーボン、有機溶材が焼失するため、微粉部分に含まれる不純物であるSiO、Al、CaOなどが優先的に集塵される。A dust collector will be installed on the kiln bottom side of the rotary kiln. Impurities contained in the fine powder part because the heat generated in the hot stove is pulled to the bottom of the kiln, extending the effective distance in the oxidizable calcination zone temperature range 800-1000 ° C, and at the same time carbon and organic melted material are burned out by oxidization SiO 2 , Al 2 O 3 , CaO and the like are preferentially collected.

ロータリーキルン原料排出側に熱風炉を設置し、燃料は再生油を使用した。燃焼時の再生油使用量は20〜40l/hr程度となる。  A hot stove was installed on the rotary kiln feedstock discharge side, and recycled oil was used as the fuel. The amount of recycled oil used during combustion is about 20 to 40 l / hr.

また、ロータリーキルン内の酸素濃度を5.0〜9.0容量%に保つことが必要となる為、エアーの打ち込みを行う。炉内酸素濃度は5容量%より低いと、カーボンと反応する酸素不足により酸化が進まない。酸素濃度が9容量%より高いと、投入するエアーにより温度低下を引き起し800℃が保てず不適となる。エアーの代わりに酸素を打ち込んでも良いが費用がかかり経済的でない。  Further, since it is necessary to maintain the oxygen concentration in the rotary kiln at 5.0 to 9.0% by volume, air is driven. If the oxygen concentration in the furnace is lower than 5% by volume, the oxidation does not proceed due to the lack of oxygen that reacts with carbon. If the oxygen concentration is higher than 9% by volume, the introduced air causes a temperature drop, and 800 ° C. cannot be maintained, which is inappropriate. Oxygen can be used instead of air, but it is expensive and not economical.

キルン内の原料充填率は15容量%以下となるよう原料供給量を調整する。原料充填率が高すぎると、キルン内の酸化反応に必要な酸素量も多く必要となるため、エアー投入量を増やす必要が生じ温度維持が困難となる。エアーの打ち込みはキルン内の焼成温度800〜1000℃を保つ程度に打ち込む必要がある。あまり打ち込み過ぎるとキルン内の温度を低下させてしまい酸化が進まない場合がある。  The raw material supply amount is adjusted so that the raw material filling rate in the kiln is 15% by volume or less. If the raw material filling rate is too high, a large amount of oxygen is required for the oxidation reaction in the kiln, so that it is necessary to increase the amount of air input, and it becomes difficult to maintain the temperature. It is necessary to drive air to such an extent that the firing temperature in the kiln is maintained at 800 to 1000 ° C. If it is driven too much, the temperature in the kiln is lowered and oxidation may not proceed.

キルンの回転速度は3.0rpm以下の範囲で調整する。キルンの回転速度はあまり速過ぎるとカーボンの酸化反応が進みにくくなる。キルン回転速度が速いと酸化可能な焼成帯温度域800〜1000℃での滞留時間を短くしてしまうからである。  The rotation speed of the kiln is adjusted within a range of 3.0 rpm or less. If the rotational speed of the kiln is too high, the oxidation reaction of carbon will not proceed easily. This is because if the kiln rotation speed is high, the residence time in the oxidizable firing zone temperature range 800 to 1000 ° C. is shortened.

上記に述べた内容はロータリーキルンの内径、全長、傾き、回転数および熱風炉の能力により異なり、調整することが出来る。  The contents described above vary depending on the inner diameter, the overall length, the inclination, the rotational speed of the rotary kiln and the capacity of the hot stove and can be adjusted.

以下に本発明の実施例を示し、本発明の特徴とするところを一層明確にする。  Examples of the present invention will be described below to further clarify the features of the present invention.

実験で得られた使用済みMgO−Cれんがの処理温度とカーボン残量の関係を酸素濃度をパラメータとして図1に示した。  FIG. 1 shows the relationship between the treatment temperature of the used MgO-C brick obtained in the experiment and the remaining amount of carbon with the oxygen concentration as a parameter.

図1に示したグラフのカーボン量は、フリーのカーボン及びマグネシア原料中に浸炭したカーボンの合量である。図1の酸化良範囲のカーボン量はマグネシアに浸炭したカーボン量のみとなる範囲である。  The amount of carbon in the graph shown in FIG. 1 is the total amount of free carbon and carbon carburized in the magnesia raw material. The amount of carbon in the good oxidation range of FIG.

図1に示すように酸化焼成後に原料中に残炭する量は、ロータリーキルンの処理温度及び炉内の酸素濃度によるところが大きい。処理温度が800℃より低いとカーボンの酸化が進まない。1000℃より高いとカーボンの酸化は進むが燃費効率が悪く経済的でない。炉内酸素濃度は5容量%より低いと、カーボンと反応する酸素不足により酸化が進まない。酸素濃度が9容量%より高いと、投入するエアーにより温度低下を引き起し800℃が保てず不適となる。よって、図1の丸で囲んだ範囲がフリーのカーボンが酸化除去され、浸炭マグネシアのみのカーボン量となる領域となる。  As shown in FIG. 1, the amount of carbon remaining in the raw material after oxidation and firing largely depends on the processing temperature of the rotary kiln and the oxygen concentration in the furnace. When the treatment temperature is lower than 800 ° C., the oxidation of carbon does not proceed. If it is higher than 1000 ° C., the oxidation of carbon proceeds, but the fuel efficiency is poor and it is not economical. If the oxygen concentration in the furnace is lower than 5% by volume, the oxidation does not proceed due to the lack of oxygen that reacts with carbon. If the oxygen concentration is higher than 9% by volume, the introduced air causes a temperature drop, and 800 ° C. cannot be maintained, which is inappropriate. Therefore, the area surrounded by a circle in FIG. 1 is an area where free carbon is oxidized and removed, and the amount of carbon is only carburized magnesia.

表1に、使用済みMgO−Cれんが原料を粒度10mm以下として、ロータリーキルンの温度と雰囲気を変えて処理した実施例および比較例を示す。
得られた浸炭マグネシア原料のカーボン量が7質量%以下の場合を良(○)とし、それ以上の場合を不良(×)として評価した。カーボン量が7質量%以上の原料はあきらかに未酸化で残ったカーボンがロータリーキルンより排出されるからである。
Table 1 shows examples and comparative examples in which the used MgO-C brick raw material was treated with a particle size of 10 mm or less and the temperature and atmosphere of the rotary kiln were changed.
The case where the amount of carbon of the obtained carburized magnesia raw material was 7% by mass or less was evaluated as good (◯), and the case where the amount of carbon was more than that was evaluated as defective (×). This is because the unoxidized carbon remaining in the raw material having a carbon amount of 7% by mass or more is discharged from the rotary kiln.

表2に本発明の方法に使用した使用済みMgO−Cれんが及び、本発明の方法により得られた浸炭マグネシア原料の化学成分、物性値を示す。  Table 2 shows the used MgO-C brick used in the method of the present invention and the chemical components and physical properties of the carburized magnesia raw material obtained by the method of the present invention.

浸炭マグネシア原料は5〜1mm、1mm以下に分級することで不純物であるSiO2、Al、CaOが1mm以下側に多く含まれる傾向があり、5〜1mmのみMgO−Cれんがに使用すれば、より耐食性の優れるれんがとなることが期待できる。
Carburized magnesia raw material tends to contain impurities SiO2, Al 2 O 3 and CaO on the side of 1 mm or less by classifying them to 5 to 1 mm or 1 mm or less, and if only 5 to 1 mm is used for MgO-C brick Therefore, it can be expected to be a brick with better corrosion resistance.

浸炭マグネシア原料と未処理原料の顕微鏡写真を図2に示した。浸炭マグネシア原料は、電融マグネシア結晶中にカーボンが浸炭しており、黒色結晶となっている。未処理原料はカーボン及び不純物であるSiO、Al、CaOが多く含まれている。有機結合材も残った状態であるため、見掛気孔率は浸炭マグネシア原料と比較すると多い状態である。Photomicrographs of the carburized magnesia raw material and the untreated raw material are shown in FIG. As for the carburized magnesia raw material, carbon is carburized in the electrofused magnesia crystal, and it becomes a black crystal. Untreated raw materials are rich in carbon and impurities such as SiO 2 , Al 2 O 3 , and CaO. Since the organic binder remains, the apparent porosity is higher than that of the carburized magnesia raw material.

次に、本発明で得られた再生マグネシア原料の評価を行った。本発明で得られた再生マグネシア原料を5〜1mm、1mm以下に分級し、0〜100質量%添加し、その残部を電融マグネシア、鱗状黒鉛、金属粉となる様に調合し、バインダーとして有機溶剤を使用して混練した後、プレス成型した。これにより、230×180×65mmの成形体を得た。この成形体を最高温度250℃で24時間乾燥し試料を作成、その特性を試験した。  Next, the recycled magnesia raw material obtained in the present invention was evaluated. The regenerated magnesia raw material obtained in the present invention is classified into 5 to 1 mm and 1 mm or less, 0 to 100% by mass is added, and the remainder is prepared so as to be fused magnesia, scaly graphite, and metal powder, and organic as a binder. After kneading using a solvent, press molding was performed. Thereby, a molded body of 230 × 180 × 65 mm was obtained. The molded body was dried at a maximum temperature of 250 ° C. for 24 hours to prepare a sample, and its characteristics were tested.

従来例1は再生原料を使用せずに、バージン原料を使用して試作したものである。従来例2は表2に示した使用済みMgO−Cれんがを未処理のまま使用し試作したものである。  Conventional Example 1 is a prototype using a virgin raw material without using a recycled raw material. Conventional Example 2 is a prototype of the used MgO-C brick shown in Table 2 that is used untreated.

再生マグネシア原料はそれぞれ表3に示す割合で添加し、その他の使用骨材はバージンマグネシア骨材を使用した。配合したMgO−Cれんがはトータルのカーボン量が6質量%となるように鱗状黒鉛の添加量を調整した。
Recycled magnesia raw materials were added in proportions shown in Table 3, and virgin magnesia aggregates were used as the other aggregates used. The added amount of scaly graphite was adjusted so that the total amount of carbon in the blended MgO-C brick was 6% by mass.

見掛気孔率、かさ比重の測定方法はJIS R2205−74に順ずる方法で行った。浸炭マグネシア原料を使用した実験例1〜4はその添加量が増えるに従って、高見掛気孔率、低かさ比重の傾向となる。  The apparent porosity and bulk specific gravity were measured according to JIS R2205-74. In Experimental Examples 1 to 4 using the carburized magnesia raw material, as the amount of addition increases, a tendency of high apparent porosity and low bulk specific gravity tends to occur.

熱伝導率はレーザーフラッシュ法で900℃の値を測定した。熱伝導率は浸炭マグネシア原料を添加するに従い低下する傾向が見られる。これは、浸炭マグネシア原料の高見掛気孔率および鱗状黒鉛の添加量減少によるものであると思われる。  The thermal conductivity was measured at 900 ° C. by a laser flash method. The thermal conductivity tends to decrease as the carburized magnesia raw material is added. This is thought to be due to the high apparent porosity of the carburized magnesia raw material and the decrease in the amount of scaly graphite added.

作成した試料を40×40×150mmに切断し電気炉で1500℃×3時間焼成後、切断し1サンプルにつき切断面4箇所の酸化層を測定しその平均値を酸化量(mm)とした。  The prepared sample was cut into 40 × 40 × 150 mm, fired in an electric furnace at 1500 ° C. for 3 hours, then cut, and the oxide layers at four cut surfaces were measured for each sample, and the average value was defined as the oxidation amount (mm).

酸化量については、浸炭マグネシア原料を添加するにしたがって、酸化量が少なくなっており耐酸化性が向上する傾向となる。これは、先に述べたとおりマグネシアに浸炭したカーボンの影響によるものと考えられる。  Regarding the oxidation amount, as the carburized magnesia raw material is added, the oxidation amount decreases and the oxidation resistance tends to be improved. This is thought to be due to the effect of carbon carburized in magnesia as described above.

耐食性の評価方法は次のとおりである。The evaluation method of corrosion resistance is as follows.

回転ドラム法にて1650℃×6時間×2日の侵食試験を塩基度2.0のスラグ条件で行い、1サンプルにつき5箇所の残寸を測定し、原寸からの減少量の平均値を侵食量(mm)とした。  Erosion test at 1650 ° C x 6 hours x 2 days by rotating drum method under slag conditions with basicity of 2.0, measure the remaining size of 5 places per sample, and erod the average value of reduction from the original size Amount (mm).

侵食試験の結果より浸炭マグネシア原料を添加するに従い、侵食量は低下する傾向が見られた。一般的に高見掛気孔率、低かさ比重のマグネシア原料を使用するとMgO−Cれんがにおいても高見掛気孔率、低かさ比重となりれんがの耐食性は低下する現象が見られる。本試験では浸炭マグネシア原料を使用する事により高見掛気孔率でもバージン品より優れた耐食性が得られることを確認した。  From the results of the erosion test, the amount of erosion tended to decrease as carburized magnesia material was added. In general, when a magnesia raw material having a high apparent porosity and a low bulk specific gravity is used, even in MgO-C brick, a phenomenon that the corrosion resistance of the brick is lowered due to a high apparent porosity and a low bulk specific gravity is observed. In this test, it was confirmed that by using carburized magnesia raw material, corrosion resistance superior to that of virgin products can be obtained even with high apparent porosity.

以上のとおり、本発明は使用済みのMgO−Cれんがを粉砕、酸化焼成することにより得られる浸炭マグネシア原料をMgO−Cれんがにリサイクル使用する事で、従来のバージン原料を使用したMgO−Cれんがと比較し、耐酸化性、耐食性が向上し、しかも低熱伝導性の特徴を持つ。  As described above, the present invention recycles the carburized magnesia raw material obtained by pulverizing and firing the used MgO-C brick into MgO-C brick, so that the MgO-C brick using the conventional virgin raw material is used. Compared to the above, it has improved oxidation resistance and corrosion resistance, and has low heat conductivity.

本発明はカーボン含有不焼成れんがについて適用できるが、MgO−Cれんがについて実施例の一例を示した。Al−MgO−Cれんがについても適用できる。Although the present invention can be applied to carbon-containing unfired bricks, an example of an embodiment was shown for MgO-C bricks. The present invention can also be applied to Al 2 O 3 —MgO—C brick.

カーボン含有不焼成れんがは使用される製鋼用取鍋、RH炉等で炭素成分の溶解による鋼製品の品質低下、いわゆるカーボンピックアップの欠点があるが、本発明の浸炭マグネシア原料を使用することでカーボンピックアップ対策にも効果が期待される。  Carbon-containing unfired bricks have a disadvantage of so-called carbon pick-up due to the deterioration of the quality of steel products due to the dissolution of carbon components in steelmaking ladles, RH furnaces, etc., but by using the carburized magnesia raw material of the present invention, carbon It is expected to be effective in picking up measures.

本発明では、使用済みMgO−Cれんがをより付加価値の高いれんがの骨材として再利用することができるので、資源の有効利用に有用であるばかりでなく、廃棄物のリサイクルにも顕著に寄与し、その産業上の利用可能性には多大なものがある。  In the present invention, since used MgO-C brick can be reused as an aggregate of brick with higher added value, it is not only useful for effective use of resources but also contributes significantly to recycling of waste. However, its industrial applicability is enormous.

Claims (3)

使用済みカーボン含有不焼成れんがを焼成処理することを特徴とする使用済みカーボン含有不焼成れんがの再生再利用方法A method for recycling and recycling used carbon-containing unfired bricks, characterized by firing used carbon-containing unfired bricks 酸素濃度5.0〜9.0%、温度800〜1000℃で焼成処理することを特徴とする使用済みカーボン含有不焼成れんがの再生再利用方法A method for recycling and recycling used carbon-containing unfired bricks, characterized by firing at an oxygen concentration of 5.0 to 9.0% and a temperature of 800 to 1000 ° C. 酸素濃度5.0〜9.0%、温度800〜1000℃で焼成処理して得た浸炭マグネシア原料を使用してMgO−Cれんがを製造することを特徴とする使用済みMgO−Cれんがの再生再利用方法Regeneration of used MgO-C brick, characterized by producing a MgO-C brick using a carburized magnesia raw material obtained by firing at an oxygen concentration of 5.0-9.0% and a temperature of 800-1000 ° C. Reuse method
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