JP2019077934A - Refractory for gas injection nozzles - Google Patents

Refractory for gas injection nozzles Download PDF

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JP2019077934A
JP2019077934A JP2017207680A JP2017207680A JP2019077934A JP 2019077934 A JP2019077934 A JP 2019077934A JP 2017207680 A JP2017207680 A JP 2017207680A JP 2017207680 A JP2017207680 A JP 2017207680A JP 2019077934 A JP2019077934 A JP 2019077934A
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refractory
metal
gas injection
central
injection nozzle
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JP6974115B2 (en
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聖司 細原
Seiji Hosohara
聖司 細原
鳥越 淳志
Atsushi Torigoe
淳志 鳥越
亮磨 藤吉
Ryoma Fujiyoshi
亮磨 藤吉
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Shinagawa Refractories Co Ltd
JFE Steel Corp
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Shinagawa Refractories Co Ltd
JFE Steel Corp
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Abstract

To enhance durability of refractory for gas injection nozzles in which one or more metal fine tubes for gas blowing are embedded.SOLUTION: This refractory is composed of a central refractory a buried with metal fine tubes and an outer peripheral refractory b. The central refractory a has a radius R+r where r=10-150 mm with respect to the radius R of a central region in which the metal tubules are arranged. The central refractory a is composed of a MgO-C brick having a C content of 30-80 mass%. The outer peripheral refractory b is composed of a MgO-C brick having a C content of 10-25 mass%. Having a normal C content, the outer peripheral refractory b has a certain abrasion resistance and erosion resistance. Since the central refractory a has a high C content, a crack due to thermal shock can be suppressed. As the center refractory a has high thermal conductivity, it is cooled by the gas flowing through the fine metal tube, thereby forming a solid (protective) film of slag or metal on the active surface side, which suppresses wear due to abrasion or erosion.SELECTED DRAWING: Figure 1

Description

本発明は、転炉や電気炉などにおいて、精錬効率や合金歩留まりの向上を目的として炉底などから溶湯内にガスを吹込むためのガス吹込みノズル用の耐火物であって、炭素含有耐火物にガス吹込み用の金属細管が1本以上埋設されたガス吹込みノズル用耐火物に関する。   The present invention is a refractory for a gas injection nozzle for blowing a gas into a molten metal from a furnace bottom or the like for the purpose of improving refining efficiency and alloy yield in a converter or an electric furnace, which is a carbon-containing refractory The present invention relates to a refractory for gas injection nozzle in which one or more metal injection tubes for gas injection are embedded.

転炉や電気炉などでは、精錬効率や合金歩留まりの向上を目的として、炉底から撹拌ガス(通常、窒素やArなどの不活性ガス)や精錬ガスを溶湯内に吹込む、いわゆる底吹きが行われる。この底吹きの方式としては、(1)内管から脱炭を目的とした酸素を、外管から溶鋼接触部位の冷却を目的とした炭化水素ガス(プロパンなど)をそれぞれ吹込む二重管方式、(2)金属管と煉瓦の隙間にスリット状の開孔を設け、その開孔から不活性ガスを吹込む方式(スリット方式)、(3)炭素含有煉瓦に複数本(数本〜数百本)の金属細管を埋設し、煉瓦の底部からガス導入管とガス溜まりを介して不活性ガスを金属細管に供給し、この金属細管から不活性ガスを吹込む方式、などがある。   In converters and electric furnaces, so-called bottom-blowing is the process of blowing stirring gas (usually an inert gas such as nitrogen or Ar) or refining gas into the melt from the furnace bottom for the purpose of improving refining efficiency and alloy yield. To be done. As this bottom-blowing system, (1) a double-pipe system in which oxygen for the purpose of decarburizing from the inner pipe and a hydrocarbon gas (such as propane) for the purpose of cooling the molten steel contact portion from the outer pipe are blown respectively (2) A slit-like opening is provided in the gap between the metal pipe and the brick, and an inert gas is blown from the opening (slit system), (3) A plurality (several to several hundreds) of carbon-containing brick There is a method in which the metal thin tube of the present invention is embedded, the inert gas is supplied to the metal thin tube from the bottom of the brick through the gas introduction pipe and the gas reservoir, and the inert gas is blown from the metal thin tube.

これらのうち(1)、(2)の方式では、羽口用煉瓦を予め定法により製造し、二重管やスリットを形成する金属管の設置部分を加工したり、2分割ないし4分割とすることで金属管を設置する空間を形成し、施工時にはガスを吹込む金属管を予めセットし、その周囲に羽口用煉瓦を施工するのが一般的である。
一方、(3)の方式で用いられるガス吹込み用プラグ(ノズル)は、マルチプル・ホール・プラグ(以下、MHPという)と呼ばれる。例えば、特許文献1(特開昭59−31810号公報)では、このMHPでは1〜20倍のガス流量(0.01〜0.20Nm/min)が制御可能とされている。このため、MHPは二重管方式やスリット方式に比べて採用が容易である。
Among them, in the methods (1) and (2), brick for tuyere is manufactured in advance according to a standard method, and the installation part of a metal pipe forming a double pipe or a slit is processed or divided into two or four. It is common to form the space which installs a metal pipe by this, set the metal pipe which blows in gas beforehand at the time of construction, and build the brick for tuyeres around it.
On the other hand, the gas injection plug (nozzle) used in the method (3) is called multiple hole plug (hereinafter referred to as MHP). For example, in patent document 1 (Unexamined-Japanese-Patent No. 59-31810), the gas flow rate (0.01-0.20 Nm < 3 > / min) of 1-20 times is made controllable by this MHP. For this reason, MHP is easier to adopt than the double pipe method or the slit method.

MHPは、ガス溜まりに接続された複数本の金属細管がマグネシア−カーボン煉瓦などの炭素含有耐火物に埋め込まれた構造であるため、その製造は、二重管方式やスリット方式のノズルとは異なり、以下のような方法が採られる。
すなわち、マグネシア原料などの骨材に鱗状黒鉛などの炭素源、ピッチや金属種、フェノール樹脂などのバインダーを加えた原料を、分散性能の高いハイスピードミキサーなどの混練手段を用いて混練し、金属細管を埋設する炭素含有耐火物を構成すべき混練物を得る。そして、この混練物の上に金属細管を敷設しながら積層状に金属細管を埋設した上で、プレス機により所定の圧力で成形を行い、その後、所定の乾燥・焼成などの加熱処理を行う方法(金属細管は、その後、ガス溜まり用の部材に溶接で接合する)、或いは、予めガス溜まり用の部材に金属細管を溶接で接合しておき、その周囲の混練物を充填した上で、プレス機により所定の圧力で成形を行い、その後、所定の乾燥を行う方法、などによりMHPが製造される。
The MHP has a structure in which a plurality of metal thin tubes connected to a gas reservoir is embedded in a carbon-containing refractory such as magnesia-carbon brick, so its production differs from double-pipe or slit-type nozzles. The following method is adopted.
That is, a raw material obtained by adding a carbon source such as scale-like graphite, a pitch, a metal species, a binder such as a phenol resin to an aggregate such as magnesia raw material is kneaded using a high speed mixer having high dispersion performance The kneaded material which should constitute the carbon containing refractories which embeds a tubule is obtained. Then, the metal capillary is embedded in a layered manner while laying the metal capillary on the kneaded product, and then molding is carried out at a predetermined pressure by a press, and thereafter a heating treatment such as predetermined drying and baking is carried out. (The metal capillary is then joined by welding to a member for the gas reservoir.) Alternatively, the metal capillary is joined beforehand to the member for the gas reservoir by welding, and the kneaded material around it is filled and pressed. The MHP is manufactured by a method of molding at a predetermined pressure by a machine and thereafter performing predetermined drying.

底吹きノズルは炉壁などの耐火物に比べて損傷量(損耗量)が大きく、炉寿命を左右する重要な部材であるため、従来、損傷抑制のための様々な提案がなされており、MHPについても、例えば、以下のような改善が提案されている。
特許文献2(特開昭63−24008号公報)では、MHPのガス吹込みノズル部分と周囲羽口を一体化させ、目地部からの先行溶損、磨耗の低減が図られている。しかし、この技術では効果が小さく、有効な対策とはなり得ない。
The bottom blowing nozzle is an important member that has a large amount of damage (wear and tear) compared to a refractory such as a furnace wall, and is an important member that affects the furnace life, so various proposals for damage control have been conventionally made. For example, the following improvements have been proposed.
In patent document 2 (Unexamined-Japanese-Patent No. 63-24008), the gas injection nozzle part and surrounding tuyere of MHP are integrated, and the advance | preceding melting loss from a joint part and abrasion reduction are achieved. However, this technique is not effective and can not be an effective countermeasure.

また、耐火物内に埋設した金属細管の浸炭による低融点化(金属細管の先行損傷)の対策として、以下のような提案がなされている。
特許文献3(特開2000−212634号公報)には、マグカーボンなどの炭素含有耐火物に埋設されたステンレス製の金属細管の浸炭を抑制するために、金属細管表面に溶射によって酸化物層を形成することが提案されている。しかし、転炉などのように長期間使用される精錬炉(例えば2ヶ月〜半年の使用期間)では、酸化物層の膜厚が十分ではなく、浸炭抑制効果が小さいという問題がある。
Further, as a measure for lowering the melting point (preceding damage of metal capillaries) by carburizing metal capillaries embedded in a refractory, the following proposals have been made.
Patent Document 3 (Japanese Patent Application Laid-Open No. 2000-212634) discloses that an oxide layer is sprayed on the surface of a metal capillary in order to suppress carburization of a stainless steel metal capillary embedded in a carbon-containing refractory such as magcarbon. It is proposed to form. However, in a smelting furnace (for example, a use period of 2 months to half a year) used for a long time such as a converter, the film thickness of the oxide layer is not sufficient, and there is a problem that the carburization suppressing effect is small.

また、特許文献4(特開2003−231912号公報)には、金属細管の浸炭を抑制するために、金属細管と炭素含有耐火物と間に耐火性焼結体を配設することが提案されている。しかし、この技術は、浸炭の抑制効果は認められるものの、多数本の金属細管を埋設するノズルでは、金属細管の間隔が狭いため耐火性焼結体を配設することが困難であり、実用化は難しい。   Patent Document 4 (Japanese Patent Laid-Open No. 2003-231912) proposes that a fire-resistant sintered body be disposed between a metal thin tube and a carbon-containing refractory in order to suppress carburization of the metal thin tube. ing. However, although this technology has an effect of suppressing carburization, it is difficult to dispose a fire-resistant sintered body because the distance between the metal capillaries is narrow with a nozzle in which a large number of metal capillaries are embedded. Is difficult.

一方、炭素含有耐火物を一旦還元焼成した後、有機物を含浸する方法を採用したものとして、以下のような提案がある。
特許文献5(特開昭58−015072号公報)では、金属Al粉末を添加したマグカーボン煉瓦を500〜1000℃で焼成加熱し、その後、炭化収率25%以上の有機物を煉瓦気孔内に含浸させる処理を行い、熱間強度の向上とともに耐食性の向上を図っている。また、特許文献6(特許第3201678号公報)では、仮焼無煙炭を0.5〜10重量%添加したマグカーボン煉瓦を600〜1500℃にて還元焼成することで、弾性率の低減による耐熱スポール性の改善が図られるとしている。さらに、焼成後にタールを含浸してもよく、この含浸により気孔の密封、強度アップ、耐消化性の向上が図られるとしている。しかし、これらの技術では効果が少なく、有効な対策とはなり得ない。
On the other hand, there is the following proposal as what adopted the method of impregnating the organic substance after reducing and firing the carbon-containing refractory once.
In patent document 5 (Japanese Patent Application Laid-Open No. 58-015072), a magcarbon brick to which metal Al powder is added is fired and heated at 500 to 1000 ° C., and then an organic matter having a carbonization yield of 25% or more is impregnated in the brick pores. Treatment to improve the hot strength and the corrosion resistance. Further, in Patent Document 6 (Japanese Patent No. 3201678), heat-resistant spall by reducing elastic modulus by reducing and baking at a temperature of 600 to 1500 ° C. a magcarbon brick to which 0.5 to 10% by weight of calcined anthracite coal is added. It is said that the improvement of Furthermore, after firing, tar may be impregnated, and it is said that sealing of the pores, enhancement of strength, and improvement of digestion resistance can be achieved by this impregnation. However, these techniques are ineffective and can not be effective measures.

特開昭59−31810号公報Japanese Patent Application Laid-Open No. 59-31810 特開昭63−24008号公報Japanese Patent Application Laid-Open No. 63-24008 特開2000−212634号公報JP 2000-212634 A 特開2003−231912号公報Unexamined-Japanese-Patent No. 2003-231912 特開昭58−15072号公報JP-A-58-15072 特許第3201678号公報Patent No. 3201678

以上のように、炭素含有耐火物に金属細管を埋設するタイプのガス吹きノズル(MHPなど)について、耐用性を高めるために耐火物材質や構造について種々検討がなされているが、十分な改善効果が得られていないのが現状である。
したがって本発明の目的は、以上のような従来技術の課題を解決し、炭素含有耐火物にガス吹込み用の金属細管が1本以上埋設されたガス吹込みノズル用耐火物において、高い耐用性を有するガス吹込みノズル用耐火物を提供することにある。
As described above, various studies have been made on the material and structure of the refractory to improve the durability of the gas blowing nozzle (MHP etc.) of the type in which the metal capillary is embedded in the carbon-containing refractory, but the sufficient improvement effect It is the present condition that is not obtained.
Accordingly, the object of the present invention is to solve the problems of the prior art as described above, and it is highly durable in a refractory for gas injection nozzle in which one or more metal thin tubes for gas injection are embedded in a carbon-containing refractory. And providing a refractory for a gas injection nozzle.

転炉や電気炉で用いられるMHPの損傷の原因については、これまで、金属細管から勢いよくガスが吹き込まれることから、ノズル稼働面近傍での溶鋼流による溶損、磨耗が主体と考えられてきた。特許文献2の対策はこの考え方に立つものである。また、浸炭などにより金属細管が先に消耗することで、損傷が大きくなるとの考え方もあり、特許文献3や特許文献4のような手法で金属細管への浸炭を防止してきた。一方、吹錬時は不活性ガスを勢いよく吹き込むために耐火物が冷却され、吹錬時と非吹錬時の間の温度差によってスポーリング損傷するのではないかという考え方、さらには、炭素含有耐火物は600℃付近で強度が最低になるので、その部分で稼働面に亀裂が入り、損傷するのではないか、などのような様々な考え方があり、結論が出ていなかった。その結果、十分な対策が行われず、上記のように必ずしも満足する耐用性が得られていないのが現状である。   As to the cause of damage to MHP used in converters and electric furnaces, gas has been blown from metal capillary vigorously so far, so it is thought that the main cause is melt damage due to molten steel flow near the nozzle operation surface and wear. The The measure of patent document 2 stands in this way of thinking. Moreover, there is also a view that damage becomes large by the metal capillary being consumed first by carburizing etc., and carburization to the metal capillary has been prevented by a method like Patent Document 3 or Patent Document 4. On the other hand, during blowing, the refractory is cooled in order to blow inert gas vigorously, and it is thought that spalling damage may occur due to the temperature difference between blowing and non-blowing, and further, carbon-containing fireproof Since the object has the lowest strength at around 600 ° C, there are various ideas such as cracking or damage to the working surface at that part, and no conclusion was drawn. As a result, sufficient measures have not been taken, and as described above, at present, satisfactory durability is not obtained.

そこで、本発明者らは、MHPの真の損傷原因を探るため、実炉で使用された使用後品(MHP)を回収し、ノズル稼働面近傍の耐火物組織について詳細に調査した。その結果、稼働面から深さ10〜20mm程度の耐火物内部で500〜600℃という非常に大きな温度変化が発生していることが判明し、さらにこの部位に稼働面と平行な亀裂を確認することができた。このような実炉使用後品の稼動面近傍の詳細な調査を重ねた結果から、MHPの損傷形態は、溶損や磨耗による損傷ではなく、稼働面近傍で生じている急激な温度勾配に起因した熱衝撃による損傷が主体であるとの結論が得られた。   Therefore, in order to find out the true cause of MHP damage, the present inventors recovered after-use products (MHP) used in an actual furnace, and investigated in detail the refractory structure in the vicinity of the nozzle operation surface. As a result, it is found that a very large temperature change of 500 to 600 ° C. is generated inside the refractory having a depth of about 10 to 20 mm from the operating surface, and a crack parallel to the operating surface is confirmed in this part. I was able to. As a result of repeated investigations near the working surface of such post-use items, the damage form of MHP is not due to damage caused by melting or wear, but to a rapid temperature gradient occurring near the working surface. It was concluded that the main cause was thermal shock damage.

そこで、本発明者らは、羽口用耐火物に発生する熱応力を小さくする材質改善について鋭意検討を重ねた結果、C含有量を高くした高熱伝導率(高熱伝導率により温度勾配が小さくなる)、低熱膨張率の耐火物が有効であることが判った。しかし、C含有量を高くすると耐摩耗性、耐溶損性の低下が著しくなり、摩耗や溶融金属による溶損によって寿命が著しく低下する。そこで、さらに検討を進めた結果、最も冷却されている金属細管周辺部(所定範囲の中心部)に高C含有量のMgO−C材を配し、その周囲(外周部)は通常のC含有量のMgO−C材とした構造とすることで、問題を解決できることを見出した。すなわち、外周部については通常のC含有量の耐火物(MgO−C材)とすることで耐摩耗性、耐溶損性の低下を抑えることができ、一方、金属細管周辺部については、C含有量を高くした高熱伝導率、低熱膨張率の耐火物(MgO−C材)とすることにより、熱衝撃による亀裂の発生を抑制できるとともに、高熱伝導率であるために金属細管を流れるガスにより冷却されることで、稼働面側にスラグや金属の凝固膜(いわゆるマッシュルーム)が形成され、この凝固膜により溶鋼から耐火物表面が遮断(保護)され、摩耗や溶損による損耗を抑制する効果が得られることを見出した。   Therefore, as a result of intensive studies on material improvement to reduce the thermal stress generated in the tuyere refractory, the present inventors have made high thermal conductivity (high thermal conductivity reduces temperature gradient by increasing C content) ), Low thermal expansion refractory has been found to be effective. However, when the C content is increased, the wear resistance and the erosion resistance decrease remarkably, and the life is remarkably reduced due to the wear and the erosion due to the molten metal. Therefore, as a result of further investigation, a high C content MgO-C material is disposed in the most cooled metal capillary peripheral portion (central portion of a predetermined range), and the periphery (peripheral portion) contains normal C It has been found that the problem can be solved by making the structure into an amount of MgO-C material. That is, by using a normal C content refractory (MgO-C material) for the outer peripheral portion, it is possible to suppress the deterioration of the wear resistance and the erosion resistance, while for the metal capillary peripheral portion, C containing By using a high thermal conductivity, low thermal expansion coefficient refractory (MgO-C material) with a high amount, it is possible to suppress the occurrence of cracks due to thermal shock and, because it has high thermal conductivity, it is cooled by gas flowing through metal capillaries The solidified film (so-called mushroom) of slag and metal is formed on the working surface side, and the surface of the refractory is shielded (protected) from the molten steel by this solidified film, and the effect of suppressing the wear and tear due to wear and dissolution is I found that I could get it.

本発明は、このような知見に基づきなされたもので、以下を要旨とするものである。
[1]炭素含有耐火物にガス吹込み用の金属細管が1本以上埋設されたガス吹込みノズル用耐火物において、
金属細管が埋設された中心部耐火物(a)と、該中心部耐火物(a)の外周を囲む外周部耐火物(b)とからなり、
ガス吹込みノズル用耐火物の平面において、埋設された全部の金属細管を包含する最小半径の仮想円(x)の半径をR(mm)としたとき、中心部耐火物(a)の外形は、仮想円(x)と同心であって半径がR+10mm〜R+150mmの円であり、
中心部耐火物(a)は、炭素含有量が30〜80質量%のMgO−C質れんがで構成され、外周部耐火物(b)は、炭素含有量が10〜25質量%のMgO−C質れんがで構成されることを特徴とするガス吹込みノズル用耐火物。
The present invention has been made based on such findings, and the gist of the present invention is as follows.
[1] A refractory for a gas injection nozzle in which one or more metal thin tubes for gas injection are embedded in a carbon-containing refractory,
It consists of a central portion refractory (a) in which metal thin tubes are embedded, and an outer peripheral portion refractory (b) surrounding the outer periphery of the central portion refractory (a),
When the radius of the imaginary circle (x) of the minimum radius including all the embedded metal capillaries is R (mm) in the plane of the gas injection nozzle refractory, the outer shape of the central refractory (a) is , Concentric with the imaginary circle (x) and having a radius of R + 10 mm to R + 150 mm,
The central refractory (a) is composed of a MgO-C brick with a carbon content of 30 to 80 mass%, and the outer refractory (b) is a MgO-C having a carbon content of 10 to 25 mass% Refractory for gas injection nozzle characterized by comprising quality bricks.

[2]上記[1]のガス吹込みノズル用耐火物において、ガス吹込みノズル用耐火物の平面において、中心部耐火物(a)の外形は、仮想円(x)と同心であって半径がR+40mm〜R+70mmの円であることを特徴とするガス吹込みノズル用耐火物。
[3]上記[1]又は[2]のガス吹込みノズル用耐火物において、中心部耐火物(a)は、炭素含有量が50〜70質量%のMgO−C質れんがで構成され、外周部耐火物(b)は、炭素含有量が15〜25質量%のMgO−C質れんがで構成されることを特徴とするガス吹き込みノズル用耐火物。
[4]上記[1]〜[3]のいずれかのガス吹込みノズル用耐火物を備えることを特徴とするガス吹込みノズル。
[2] In the refractory for gas injection nozzle according to the above [1], in the plane of the refractory for gas injection nozzle, the outer shape of the central refractory (a) is concentric with the imaginary circle (x) and has a radius Is a circle of R + 40 mm to R + 70 mm, and the refractory for gas injection nozzles characterized by the above-mentioned.
[3] In the refractory for gas blowing nozzle according to the above [1] or [2], the central refractory (a) is composed of an MgO-C masonry brick having a carbon content of 50 to 70% by mass, and the outer periphery The refractory for a gas injection nozzle characterized in that the part refractory (b) is composed of an MgO-C brick having a carbon content of 15 to 25% by mass.
[4] A gas injection nozzle comprising the refractory for gas injection nozzle according to any one of the above [1] to [3].

本発明のガス吹込みノズル用耐火物は、熱衝撃による亀裂の発生が抑制されるため高い耐用性を有する。このため、このガス吹込みノズル用耐火物を用いることにより、損傷速度が小さい高寿命のガス吹込みノズルを得ることができる。   The refractory for gas injection nozzle of the present invention has high durability because the occurrence of cracking due to thermal shock is suppressed. Therefore, by using this gas injection nozzle refractory, it is possible to obtain a long life gas injection nozzle with a low damage rate.

本発明のガス吹込みノズル用耐火物の一実施形態を示す平面図The top view which shows one Embodiment of the refractory for gas injection nozzles of this invention

本発明は、炭素含有耐火物にガス吹込み用の金属細管が1本以上埋設されたガス吹込みノズル用耐火物であり、金属細管が埋設された中心部耐火物aと、この中心部耐火物aの外周を囲む外周部耐火物bとからなる。
上述のとおり、MHP羽口の損耗の主因は熱衝撃である。特に、MHP羽口の金属細管周辺部は、金属細管を流れるガスによって冷却されるため、熱応力も大きくなる。熱衝撃や熱応力を抑制するためには、MgO−C質れんがのC含有量を高くすることが有効であるが、一方で、C含有量を高くすると溶鋼に対して溶解しやすくなり、耐摩耗性、耐溶損性が低下することが知られている。この点に関して、本発明者らは、C含有量を高くした金属細管周辺部は、高熱伝導率であるために金属細管を流れるガスにより冷却され、その結果、稼働面側にスラグや金属の凝固膜(マッシュルーム)が形成され、この凝固膜により溶鋼から耐火物表面が保護され、摩耗や溶損による損耗を抑制する効果が得られることを見出した。このため本発明では、ガス吹込みノズル用耐火物を、金属細管が埋設された中心部耐火物aと、この中心部耐火物aの外周を囲む外周部耐火物bで構成し、中心部耐火物aを高C含有量のMgO−C質れんがで構成する。
The present invention is a refractory for a gas injection nozzle in which one or more metal capillaries for gas injection are embedded in a carbon-containing refractory, and a central refractory a in which the metal capillaries are embedded; It consists of an outer peripheral refractory b surrounding the outer periphery of the object a.
As mentioned above, the main cause of MHP tuyere wear is thermal shock. In particular, the metal capillary peripheral portion of the MHP tuyere is cooled by the gas flowing through the metal capillary, so the thermal stress also increases. In order to suppress thermal shock and thermal stress, it is effective to increase the C content of the MgO-C brick, but on the other hand, if the C content is increased, it becomes easy to melt in molten steel, and it is resistant to It is known that the abrasion resistance and the erosion resistance decrease. In this regard, the inventors of the present invention found that the peripheral portion of the metal capillary having a high C content is cooled by the gas flowing through the metal capillary because of its high thermal conductivity, and as a result, slag and metal solidify on the working surface side. It has been found that a film (mushroom) is formed, the surface of the refractory is protected from molten steel by this solidified film, and the effect of suppressing the wear and tear due to wear and erosion is obtained. For this reason, in the present invention, the refractory for gas injection nozzle is composed of a central portion refractory a in which metal thin tubes are embedded and an outer peripheral portion refractory b surrounding the outer periphery of the central portion refractory a. The object a is composed of a high C content MgO-C brick.

ここで、高C含有量のMgO−C質れんがで構成する中心部耐火物aは、上述したような効果を得るために、以下に示すような所定の大きさ(外形)にする必要がある。図1に示すように、ガス吹込みノズル用耐火物の平面(稼働面)において(すなわち平面として見た場合において)、埋設された全部の金属細管を包含する最小半径の仮想円xの半径をR(mm)としたとき、中心部耐火物aの外形は、仮想円xと同心であって半径がR+10mm〜R+150mmの円とする。すなわち、図1において、中心部耐火物aの外形をなす円は、半径がR+rであってr=10〜150mmである。中心部耐火物aの外形をなす円の半径がR+10mm未満では、金属細管が外周部耐火物bとの境界に近すぎるため、耐火物成型時に金属細管の変形等が生じるおそれがあり、一方、中心部耐火物aの外形をなす円の半径がR+150mmを超えると、中心部耐火物aの稼働面にいわゆるマッシュルームに覆われない部分が生じ、溶鋼との接触による損傷が生じる。
以上の観点からより好ましい条件としては、中心部耐火物aの外形を、仮想円xと同心であって半径がR+40mm〜R+70mmの円とすること、すなわち、図1において、中心部耐火物aの外形をなす円の半径がR+rであってr=40〜70mmであることが好ましい。
Here, in order to obtain the effect as described above, the central portion refractory a composed of a high C content MgO-C material brick needs to have a predetermined size (outer shape) as shown below . As shown in FIG. 1, in the plane (working surface) of the gas-blowing nozzle refractory (that is, viewed as a plane), the radius of the imaginary circle x of the minimum radius including all the embedded metal capillaries is When R (mm), the outer shape of the central portion refractory a is concentric with the imaginary circle x and is a circle having a radius of R + 10 mm to R + 150 mm. That is, in FIG. 1, the circle forming the outer shape of the central portion refractory a has a radius of R + r and r = 10 to 150 mm. If the radius of the circle forming the outer shape of the central portion refractory a is less than R + 10 mm, the metal thin tube is too close to the boundary with the outer peripheral portion refractory b, and deformation of the metal thin tube may occur during refractory molding. When the radius of the circle forming the outer shape of the central portion refractory a exceeds R + 150 mm, a portion not covered by so-called mushrooms is formed on the working surface of the central portion refractory a, and damage due to contact with molten steel occurs.
From the above viewpoint, as a more preferable condition, the outer shape of the central refractory a should be a circle concentric with the imaginary circle x and having a radius of R + 40 mm to R + 70 mm, that is, in FIG. It is preferable that the radius of the circle forming the outer shape is R + r and r = 40 to 70 mm.

中心部耐火物aは、炭素含有量が30〜80質量%、好ましくは50〜70質量%のMgO−C質れんがで構成される。このMgO−C質れんがの炭素含有量が30質量%未満では耐熱衝撃性が十分ではなく、一方、80質量%を超えると溶鋼に対する耐食性が劣り、信頼性に欠ける。
一方、外周部耐火物bは、炭素含有量が10〜25質量%、好ましくは15〜25質量%のMgO−C質れんがで構成される。このMgO−C質れんがの炭素含有量が10質量%未満では、熱衝撃による損傷が大きくなり、一方、25質量%を超えると耐摩耗性や耐溶損性に劣るため、満足する耐用性が得られない。
The central refractory a is composed of an MgO-C brick having a carbon content of 30 to 80% by mass, preferably 50 to 70% by mass. If the carbon content of the MgO-C brick is less than 30% by mass, the thermal shock resistance is not sufficient, while if it exceeds 80% by mass, the corrosion resistance to molten steel is poor and the reliability is lost.
On the other hand, the outer peripheral refractory b is composed of an MgO-C brick having a carbon content of 10 to 25% by mass, preferably 15 to 25% by mass. If the carbon content of this MgO-C brick is less than 10% by mass, the damage due to thermal shock becomes large, while if it exceeds 25% by mass, the wear resistance and the erosion resistance are inferior, and satisfactory durability is obtained. I can not.

金属細管の材質は特には限定されないが、融点が1300℃以上の金属材料を用いることが好ましい。例えば、鉄、クロム、コバルト、ニッケルの1種以上を含む金属材料(金属又は合金)が挙げられ、なかでも特に、ステンレス鋼(フェライト系、マルテンサイト系、オーステナイト系)、普通鋼、耐熱鋼などが一般的である。金属細管は、通常、内径が1〜4mm程度、管厚が1〜2mm程度である。金属管の内径が1mm未満では、炉内の溶融金属の撹拌に十分なガスの供給が困難となるおそれがあり、4mmを超えると金属細管内に溶融金属が流入して閉塞するおそれがある。
炭素含有耐火物内に埋設される金属細管の本数は特に制限はなく、必要とされるガス吹き流量や稼働部の面積によって適宜選択される。転炉などの高流量が必要とされるものでは、一般に60〜250本程度の金属細管が埋設される。また、電気炉や取鍋のようにガス吹き流量が小さい場合には、一般に1本〜数10本程度の金属細管が埋設される。
Although the material of the metal thin tube is not particularly limited, it is preferable to use a metal material having a melting point of 1300 ° C. or more. For example, metal materials (metals or alloys) containing one or more of iron, chromium, cobalt and nickel can be mentioned, and in particular, stainless steel (ferritic, martensitic, austenitic), ordinary steel, heat-resistant steel, etc. Is common. The metal thin tube usually has an inner diameter of about 1 to 4 mm and a tube thickness of about 1 to 2 mm. If the inner diameter of the metal tube is less than 1 mm, it may be difficult to supply a gas sufficient for stirring the molten metal in the furnace, and if it exceeds 4 mm, the molten metal may flow into the metal capillary and may be blocked.
The number of metal capillaries embedded in the carbon-containing refractory is not particularly limited, and may be appropriately selected depending on the required gas blowing flow rate and the area of the working part. In the case where a high flow rate is required, such as a converter, generally about 60 to 250 metal capillaries are embedded. In addition, when the gas blowing flow rate is small as in an electric furnace or a ladle, generally, one to several tens of metal thin tubes are embedded.

次に、本発明のガス吹き込みノズル用耐火物の製造方法について説明する。
炭素含有耐火物(中央部耐火物a、外周部耐火物b)の主たる原料は、骨材と炭素源であるが、その他の添加材料及びバインダーなどを含む場合がある。
炭素含有耐火物の骨材には、マグネシア、アルミナ、ドロマイト、ジルコニア、クロミア、スピネル(アルミナ−マグネシア、クロミア−マグネシア)などが適用できるが、本発明では、溶融金属や溶融スラグに対する耐食性の観点から主たる骨材としてマグネシアを用いる。
Next, the manufacturing method of the refractory for gas blowing nozzles of this invention is demonstrated.
The main raw materials of the carbon-containing refractories (central refractory a and peripheral refractory b) are aggregate and carbon source, but may contain other additive materials, binders and the like.
For aggregates of carbon-containing refractories, magnesia, alumina, dolomite, zirconia, chromia, spinel (alumina-magnesia, chromia-magnesia), etc. can be applied, but in the present invention, from the viewpoint of corrosion resistance to molten metal and molten slag Use magnesia as the main aggregate.

また、炭素含有耐火物の炭素源は特には限定されず、鱗状黒鉛、膨張黒鉛、土壌黒鉛、仮焼無煙炭、石油系ピッチ、カーボンブラックなど一般的に使用されるものが適用可能である。炭素源の添加量は、上述した中心部耐火物aと外周部耐火物bの各炭素含有量に応じて決められる。
上述した骨材と炭素源以外の添加材料としては、例えば、金属Al、金属Si、Al−Mg合金などの金属種、SiC、BCなどの炭化物が挙げられ、これらを1種以上を含む場合がある。これら添加材料の配合量は、通常3.0質量%以下である。
炭素含有耐火物の原料は、一般にバインダーを含む。バインダーには、フェノール樹脂、液状ピッチなど、一般的に定形耐火物のバインダーとして適用できるものが使用できる。バインダーの配合量は、通常1〜5質量%(外掛け質量%)程度である。
Further, the carbon source of the carbon-containing refractory is not particularly limited, and commonly used materials such as flaky graphite, expanded graphite, soil graphite, calcined anthracite, petroleum pitch, carbon black and the like are applicable. The addition amount of the carbon source is determined in accordance with the respective carbon contents of the above-described central refractory a and the outer peripheral refractory b.
Examples of the additive material other than the aggregate and the carbon source described above include metal species such as metal Al, metal Si, Al-Mg alloy, and carbides such as SiC and B 4 C, and these include one or more of them. There is a case. The blending amount of these additive materials is usually 3.0% by mass or less.
Raw materials of carbon-containing refractories generally contain a binder. As the binder, one that can be generally applied as a binder for fixed refractories such as phenol resin and liquid pitch can be used. The blending amount of the binder is usually about 1 to 5% by mass (externally applied mass%).

本発明のガス吹込みノズル用耐火物の製造には既知の製法が適用でき、その一例を以下に挙げるが、これに限定されるものではない。
まず、中心部耐火物a用と外周部耐火物b用の各耐火物原料をそれぞれ混合し、ミキサーで混練して混練物とする。金属細管を中心部耐火物a用の混練物内の所定の位置に配置した後、一軸プレスにて成形し、金属細管が埋設された中心部耐火物aを製作する。さらに、この中心部耐火物aの周囲に外周部耐火物b用の混練物を充填した上で、等方静圧成形(CIP成形)により一体化し、ガス吹込みノズル用耐火物となる母材を成形する。その後、その母材に定法により乾燥などの所定の加熱処理を施す。また、必要に応じて、外形を整えるための加工などを適宜行ってもよい。
Known production methods can be applied to the production of the refractory for a gas injection nozzle of the present invention, and one example thereof is mentioned below, but it is not limited thereto.
First, the respective refractory raw materials for the central refractory a and the outer peripheral refractory b are respectively mixed, and are kneaded by a mixer to obtain a kneaded product. After arranging the metal thin tube at a predetermined position in the kneaded product for the central portion refractory a, it is formed by a uniaxial press to manufacture the central portion refractory a in which the metal thin tube is embedded. Furthermore, after filling the kneaded material for the outer peripheral portion refractory b around the central portion refractory a, a base material to be integrated by isotropic static pressure molding (CIP molding) to become a refractory for gas injection nozzle Molding. Thereafter, the base material is subjected to a predetermined heat treatment such as drying according to a standard method. Moreover, you may perform the process for adjusting an external shape suitably as needed.

中心部耐火物aの加圧成形方法としては、成形枠内に初めに少量の混練物を充填して加圧後、金属細管を所定の位置に配置した上で、所定量の混練物を充填して加圧することを繰り返し行う多段加圧成形方式や、金属細管が加圧時の混練物の移動と共に移行するように金属細管両端の保持しつつ、全量の混練物とともに1回の加圧で成形する単回加圧成形方式などで行うことができる。
また、金属細管とガス溜まり部との接合は、中心部耐火物aの成形後、母材の成形後、或いは母材の加熱処理後のいずれかの段階で両者を溶接する方法、中心部耐火物aの成形時に、予めガス溜まり部の上面板を溶接した金属細管を中心部耐火物a用の混練物内に配置する方法などを適宜選択することができる。
As a pressure forming method of the central refractory a, a small amount of the kneaded material is first filled in the forming frame and pressurized, and then the metal thin tube is disposed at a predetermined position, and then the predetermined amount of the kneaded material is filled. Multi-stage pressure forming method that repeatedly performs pressing and pressing, and holding the both ends of the metal thin tube so that the metal thin tube moves with the movement of the kneaded material at the time of pressure It can be carried out by a single pressure molding method or the like for molding.
In addition, the method of welding the metal thin tube and the gas reservoir part together after forming the core portion refractory a, after forming the base material, or at any stage after the heat treatment of the base material At the time of forming the object a, a method of disposing a metal thin tube in which the upper surface plate of the gas reservoir portion is welded in advance in the kneaded material for the central portion refractory a can be appropriately selected.

炭素含有耐火物の原料の混練方法には特に制限はなく、ハイスピードミキサー、タイヤミキサー(コナーミキサー)、アイリッヒミキサーなど、定形耐火物の混練設備として用いられる混練手段を用いればよい。
混練物の成形には、油圧式プレス、フリクションプレスなどの一軸成形機や等方静圧成形(CIP)など、耐火物の成形に使用される一般的なプレス機が使用できる。
成形した炭素含有耐火物は、乾燥温度180℃〜350℃、乾燥時間5〜30時間程度で乾燥させればよい。
There is no particular limitation on the method of kneading the raw material of the carbon-containing refractory, and a kneading means used as kneading equipment for fixed refractories such as a high speed mixer, a tire mixer (conner mixer), an Eirich mixer, etc. may be used.
For molding of the kneaded material, a common press used for molding of a refractory such as a hydraulic press, a uniaxial press such as a friction press or isotropic static pressure molding (CIP) can be used.
The formed carbon-containing refractory may be dried at a drying temperature of 180 ° C. to 350 ° C. and a drying time of about 5 to 30 hours.

図1に示すように同心円状に81本の金属細管を配置したガス吹込みノズル用耐火物を表1〜表4に示す条件で製造した。
ガス吹込みノズル用耐火物の平面において、埋設された全部の金属細管を包含する最小半径の仮想円xの半径Rは50mmであり、r=8〜200mmの範囲で中心部耐火物aの半径R+rを変化させた。
炭素含有耐火物に埋設する金属細管としては、普通鋼又はステンレス鋼(SUS304)製の外径3.5mm、内径2.0mmのものを用いた。
各耐火物原料を表1〜表4に示す割合でそれぞれ混合し、ミキサーで混練した。金属細管を中心部耐火物a用の混練物内に配置して一軸プレスにて中心部耐火物aを成形した。さらに、その中心部耐火物aの周囲に外周部耐火物b用の混練物を充填した上で、CIP成形により母材を成形した。その後、その母材を定法により乾燥処理し、製品とした。
As shown in FIG. 1, a refractory for gas injection nozzle in which 81 metal thin tubes were arranged concentrically was manufactured under the conditions shown in Tables 1 to 4.
The radius R of the virtual circle x of the smallest radius including all the embedded metal capillaries is 50 mm in the plane of the gas injection nozzle refractory, and the radius of the central refractory a in the range of r = 8 to 200 mm. R + r was changed.
As a metal capillary embedded in the carbon-containing refractory, one having an outer diameter of 3.5 mm and an inner diameter of 2.0 mm made of ordinary steel or stainless steel (SUS 304) was used.
Each refractory raw material was respectively mixed in the ratio shown to Table 1-Table 4, and it knead | mixed with the mixer. The metal thin tube was disposed in the kneaded product for the central portion refractory a, and the central portion refractory a was formed by a uniaxial press. Furthermore, after filling the kneaded material for the outer peripheral portion refractory b around the central portion refractory a, the base material was formed by CIP molding. Thereafter, the base material was subjected to a drying process according to a standard method to obtain a product.

製造された発明例と比較例のガス吹込みノズル用耐火物を250トン転炉の底吹き羽口周辺の炉底煉瓦に使用した。それぞれ2500〜2800ch使用後、れんがの残厚から損耗速度(mm/ch)を求め、比較例1の損耗速度を“1”とした損耗速度比(指数)を求めた。その結果を表1〜表4に示す。
表1〜表4に示されるように、本発明例のガス吹込みノズル用耐火物は、損耗速度が小さく、優れた耐用性を有していることが判る。また、本発明例のなかでも、中心部耐火物aのMgO−C質れんがの炭素含有量が50〜70質量%で、外周部耐火物bのMgO−C質れんがの炭素含有量が15〜25質量%のものは、特に優れた耐用性を有している。また、本発明例のなかでも、中心部耐火物aの半径がR+40mm〜R+70mmのものは、特に優れた耐用性を有している。
The refractories for the gas injection nozzle of the manufactured invention example and comparative example were used for the hearth brick around the bottom blowing nozzle of the 250 ton converter. After each use of 2500 to 2800 ch, the wear rate (mm / ch) was determined from the remaining thickness of the brick, and the wear rate ratio (index) with the wear rate of Comparative Example 1 as "1" was determined. The results are shown in Tables 1 to 4.
As shown in Tables 1 to 4, it can be seen that the refractory for gas injection nozzle of the inventive example has a low wear rate and has excellent durability. Further, among the inventive examples, the carbon content of the MgO-C brick of the central refractory a is 50 to 70% by mass, and the carbon content of the MgO-C brick of the outer peripheral refractory b is 15 to 15 The 25% by weight has particularly good durability. Further, among the examples of the present invention, the one having a radius of R + 40 mm to R + 70 mm of the central portion refractory a has particularly excellent durability.

Figure 2019077934
Figure 2019077934

Figure 2019077934
Figure 2019077934

Figure 2019077934
Figure 2019077934

Figure 2019077934
Figure 2019077934

a 中心部耐火物
b 外周部耐火物
x 仮想円
a central refractory b peripheral refractory x virtual circle

Claims (4)

炭素含有耐火物にガス吹込み用の金属細管が1本以上埋設されたガス吹込みノズル用耐火物において、
金属細管が埋設された中心部耐火物(a)と、該中心部耐火物(a)の外周を囲む外周部耐火物(b)とからなり、
ガス吹込みノズル用耐火物の平面において、埋設された全部の金属細管を包含する最小半径の仮想円(x)の半径をR(mm)としたとき、中心部耐火物(a)の外形は、仮想円(x)と同心であって半径がR+10mm〜R+150mmの円であり、
中心部耐火物(a)は、炭素含有量が30〜80質量%のMgO−C質れんがで構成され、外周部耐火物(b)は、炭素含有量が10〜25質量%のMgO−C質れんがで構成されることを特徴とするガス吹込みノズル用耐火物。
In a refractory for gas injection nozzle in which one or more metal fine tubes for gas injection are embedded in a carbon-containing refractory,
It consists of a central portion refractory (a) in which metal thin tubes are embedded, and an outer peripheral portion refractory (b) surrounding the outer periphery of the central portion refractory (a),
When the radius of the imaginary circle (x) of the minimum radius including all the embedded metal capillaries is R (mm) in the plane of the gas injection nozzle refractory, the outer shape of the central refractory (a) is , Concentric with the imaginary circle (x) and having a radius of R + 10 mm to R + 150 mm,
The central refractory (a) is composed of a MgO-C brick with a carbon content of 30 to 80 mass%, and the outer refractory (b) is a MgO-C having a carbon content of 10 to 25 mass% Refractory for gas injection nozzle characterized by comprising quality bricks.
ガス吹込みノズル用耐火物の平面において、中心部耐火物(a)の外形は、仮想円(x)と同心であって半径がR+40mm〜R+70mmの円であることを特徴とする請求項1に記載のガス吹込みノズル用耐火物。   The external shape of the central refractory (a) is a circle concentric with the imaginary circle (x) and having a radius of R + 40 mm to R + 70 mm in a plane of the gas blowing nozzle refractory. Refractory for gas injection nozzle according to the description. 中心部耐火物(a)は、炭素含有量が50〜70質量%のMgO−C質れんがで構成され、外周部耐火物(b)は、炭素含有量が15〜25質量%のMgO−C質れんがで構成されることを特徴とする請求項1又は2に記載のガス吹き込みノズル用耐火物。   The central refractory (a) is composed of a 50 to 70% by mass MgO-C brick with a carbon content of, and the outer peripheral refractory (b) is a MgO-C having a carbon content of 15 to 25% by mass. The refractory for a gas injection nozzle according to claim 1 or 2, wherein the refractory is made of a quality brick. 請求項1〜3のいずれかに記載のガス吹込みノズル用耐火物を備えることを特徴とするガス吹込みノズル。   A gas injection nozzle comprising the refractory for gas injection nozzle according to any one of claims 1 to 3.
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WO2020209173A1 (en) * 2019-04-09 2020-10-15 Jfeスチール株式会社 Lance nozzle
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CN111774560A (en) * 2020-07-25 2020-10-16 莱芜钢铁集团银山型钢有限公司 LF refining ladle microporous ceramic rod breathable upper nozzle pocket brick and argon blowing control method thereof
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