JP2017110280A - Molten steel vacuum processing vessel - Google Patents
Molten steel vacuum processing vessel Download PDFInfo
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- JP2017110280A JP2017110280A JP2015247657A JP2015247657A JP2017110280A JP 2017110280 A JP2017110280 A JP 2017110280A JP 2015247657 A JP2015247657 A JP 2015247657A JP 2015247657 A JP2015247657 A JP 2015247657A JP 2017110280 A JP2017110280 A JP 2017110280A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 45
- 239000010959 steel Substances 0.000 title claims abstract description 45
- 239000011449 brick Substances 0.000 claims abstract description 69
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 11
- 239000001301 oxygen Substances 0.000 claims abstract description 11
- 238000007664 blowing Methods 0.000 claims abstract description 8
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 56
- 239000000395 magnesium oxide Substances 0.000 claims description 28
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 abstract description 9
- 229910001882 dioxygen Inorganic materials 0.000 abstract description 9
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 14
- 239000011651 chromium Substances 0.000 description 14
- 238000010304 firing Methods 0.000 description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 8
- 229910052804 chromium Inorganic materials 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 5
- 229910000423 chromium oxide Inorganic materials 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 238000009489 vacuum treatment Methods 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
- Furnace Housings, Linings, Walls, And Ceilings (AREA)
Abstract
【課題】酸素ガスを吹き込む溶鋼真空処理容器の炉壁の耐用性を向上させる。
【解決手段】溶鋼真空処理容器の炉壁において、酸素吹き込みに伴うスプラッシュが接触する部位に、見掛気孔率が１１．５％以下で圧縮強度が１１５ＭＰａ以上のリボンドマグクロれんがを配置した。
【選択図】なしThe durability of a furnace wall of a molten steel vacuum processing vessel into which oxygen gas is blown is improved.
Ribbon magcro bricks having an apparent porosity of 11.5% or less and a compressive strength of 115 MPa or more are disposed on the furnace wall of a molten steel vacuum processing vessel at a site where splash caused by oxygen blowing comes into contact.
[Selection figure] None
Description
本発明は、耐火物で内張りした溶鋼真空処理容器に関し、特にＲＨ炉、ＤＨ炉及びＶＯＤ炉などの酸素ガスを吹き込んで精錬を行う溶鋼真空処理容器に関する。 The present invention relates to a molten steel vacuum processing vessel lined with a refractory, and more particularly to a molten steel vacuum processing vessel that performs refining by blowing oxygen gas, such as an RH furnace, a DH furnace, and a VOD furnace.
鉄製品を製造する製鋼プロセスでは、ＲＨ炉、ＤＨ炉及びＶＯＤ炉などの溶鋼真空処理容器において脱炭又は溶鋼昇熱のために、例えば特許文献１に示すように真空槽内の溶鋼面上から酸素ガスを吹き付ける酸素処理を行う場合があるが、このような酸素処理を行う溶鋼真空処理容器においては炉壁の損耗が大きくなる問題がある。この損耗は局部的に生じることが特徴で他の部位に比較して損耗量が１．５〜３．５倍に達し、容器全体で見た場合、非常にアンバランスな損耗プロフィールとなる。よって、その他の部位は残厚に余力があるにも拘らず、この局部的な損耗のために廃却とせざるを得ず、非効率的であった。 In a steelmaking process for producing iron products, for example, as shown in Patent Document 1, from the surface of the molten steel in a vacuum tank, for decarburization or molten steel heating in a molten steel vacuum processing vessel such as an RH furnace, a DH furnace, and a VOD furnace. There is a case where oxygen treatment in which oxygen gas is blown is performed. However, in a molten steel vacuum treatment vessel that performs such oxygen treatment, there is a problem that wear of the furnace wall is increased. This wear is characterized by local occurrence, and the amount of wear reaches 1.5 to 3.5 times that of other parts. When viewed as a whole container, the wear profile is very unbalanced. Therefore, although other parts had a surplus in the remaining thickness, they were forced to be discarded due to this local wear and were inefficient.
溶鋼真空処理容器の内張り用耐火物としては、マグクロれんが（マグネシアクロムれんが）が広く使用されている。そして、このマグクロれんがは、使用する原料の組み合わせによって、（１）ダイレクトボンドれんが、（２）リボンドれんが、（３）セミリボンドれんがの３種類に分類できる。ダイレクトボンドれんがは、マグネシアクリンカーとクロム鉱を主原料とする配合物を混練、成形、焼成して得られるれんがで、比較的耐スポール性に優れている反面、見掛気孔率が大きくなるため耐食性はやや劣っている。リボンドれんがはマグネシアクリンカーとクロム鉱及び／又は酸化クロムを電気炉で溶融あるいは高温で焼成して得られたマグクロクリンカー（マグネシアクロムクリンカー）のみ、あるいは酸化クロムを添加した配合物を混練、成形、焼成して得られるれんがで、比較的焼結しやすいため緻密な組織を有することで耐食性及び耐磨耗性に優れているが、耐スポール性には劣っている。セミリボンドれんがは、ダイレクトボンドれんがとリボンドれんがの中間的な特性を有するれんがで、マグクロクリンカーとマグネシアクリンカー及び／又はクロム鉱を併用している。 As a refractory for lining the molten steel vacuum processing vessel, magcro brick (magnesia chrome brick) is widely used. The magcro bricks can be classified into three types: (1) direct bond brick, (2) ribbon brick, and (3) semi-ribbon brick, depending on the combination of raw materials used. Direct bond brick is a brick obtained by kneading, molding, and firing a compound mainly composed of magnesia clinker and chromium ore, and it is relatively excellent in spall resistance, but it has a high apparent porosity and is corrosion resistant. Slightly inferior. Rebond bricks are kneaded and molded with only magnesia clinker (magnesia chrome clinker) obtained by melting magnesia clinker and chromium ore and / or chromium oxide in an electric furnace or firing at high temperature, or a compound added with chromium oxide. Brick obtained by firing is relatively easy to sinter and has a dense structure, which is excellent in corrosion resistance and wear resistance, but inferior in spall resistance. Semi-rigid bricks have intermediate properties between direct bond bricks and ribbon bricks, and use a combination of magcro clinker and magnesia clinker and / or chromium ore.
マグクロれんがの溶鋼真空処理容器への適用に関し、特許文献２には、電融マグクロ原料とクロム鉱とを配合し、１７５０℃以上で焼成して得られた見掛気孔率が１２．４％から１３．２％のマグネシア−クロム質れんがで内張りしてなる溶鋼真空処理容器が開示されている。また、特許文献３には、電融マグネシア−クロムクリンカー、天然クロム鉱石、海水マグネシア、及び酸化クロムを含有するセミリボンド型マグネシア−クロム質れんがにおいて、平均粒径１５μｍ以下のＺｒＯ２微粉を１〜５重量％添加した焼成マグネシア−クロム質れんがが開示され、ＡＯＤ炉の羽口周辺及びスラグラインにおいて耐用性に優れていることが記載されている。 Regarding the application of magcro bricks to a molten steel vacuum processing vessel, Patent Document 2 discloses that the apparent porosity obtained by blending an electromelted magcro raw material and chromium ore and firing at 1750 ° C. or higher is 12.4%. A molten steel vacuum treatment vessel lined with 13.2% magnesia-chromic brick is disclosed. Further, Patent Document 3 discloses 1 to 5 fine ZrO 2 powders having an average particle size of 15 μm or less in an electrofused magnesia-chrome clinker, natural chromium ore, seawater magnesia, and semi-ribboned magnesia-chromic brick containing chromium oxide. A calcined magnesia-chromic brick added by weight% is disclosed, and is described as having excellent durability in the vicinity of tuyeres and slag lines of AOD furnaces.
しかしながら、本発明者等が特許文献１及び特許文献２のマグクロれんがを酸素処理を行うＲＨ炉の炉壁にライニングして使用したところ、依然として炉壁の局部損耗が発生し耐用性が不十分であった。 However, when the inventors lined and used the magcro bricks of Patent Document 1 and Patent Document 2 on the furnace wall of an RH furnace that performs oxygen treatment, local wear of the furnace wall still occurred and the durability was insufficient. there were.
そこで本発明が解決しようとする課題は、酸素ガスを吹き込む溶鋼真空処理容器の炉壁の耐用性を向上させることにある。 Therefore, the problem to be solved by the present invention is to improve the durability of the furnace wall of the molten steel vacuum processing vessel into which oxygen gas is blown.
本発明者等がＲＨ炉において、その炉壁の局部損耗の原因について調査したところ、酸素ガスを溶鋼面に吹き付けることによって溶鋼、酸化鉄などを主成分とするスプラッシュが発生し、図１のように矢印方向へ飛んで炉壁（側壁）に当たることで、磨耗と溶損によってスプラッシュが当たる部分のみが局部的に損耗していることがわかった。 When the present inventors investigated the cause of local wear of the furnace wall in the RH furnace, a spray mainly composed of molten steel, iron oxide, etc. was generated by blowing oxygen gas onto the molten steel surface, as shown in FIG. It was found that only the portion hit by the splash due to wear and melting was locally worn by flying in the direction of the arrow and hitting the furnace wall (side wall).
そこで、本発明者等は、局部損耗の防止のためにれんがの耐磨耗性と耐溶損性を向上することが有効と考えて種々検討した結果、見掛気孔率が１１．５％以下で圧縮強度が１１５ＭＰａ以上のリボンドマグクロれんがを、ＲＨ炉において酸素吹き込みに伴うスプラッシュが当たる（接触する）部位の側壁に配置したところ局部損耗が大幅に改善されることを見出した。 Therefore, the present inventors have conducted various studies considering that it is effective to improve the wear resistance and melt resistance of bricks to prevent local wear. As a result, the apparent porosity is 11.5% or less. It has been found that local wear is greatly improved when a ribbon-type magcro brick having a compressive strength of 115 MPa or more is disposed on the side wall of the portion where the splash due to oxygen blowing hits (contacts) in the RH furnace.
すなわち本発明は、次の（１）から（５）の溶鋼真空処理容器を提供する。
（１）酸素吹き込みに伴うスプラッシュが接触する部位に、見掛気孔率が１１．５％以下で圧縮強度が１１５ＭＰａ以上のリボンドマグクロれんがを配置した溶鋼真空処理容器。
（２）リボンドマグクロれんがは、ＺｒＯ２の含有量が０．１質量％以上５質量％以下である（１）に記載の溶鋼真空処理容器。
（３）リボンドマグクロれんがは、ＺｒＯ２の含有量が０．５質量％以上３質量％以下である（１）に記載の溶鋼真空処理容器。
（４）リボンドマグクロれんがは、ＭｇＯの含有量が５４質量％以上７５質量％、Ｃｒ２Ｏ３の含有量が１９質量％以上３０質量％以下であって、かつＭｇＯとＣｒ２Ｏ３とＺｒＯ２との合量が８６質量％以上である（２）又は（３）に記載の溶鋼真空処理容器。
（５）スプラッシュが接触しない部位には、ダイレクトボンドマグクロれんが、セミリボンドマグクロれんが及びマグネシアカーボンれんがのうち１種以上を配置した（１）から（４）のいずれかに記載の溶鋼真空処理容器。
That is, the present invention provides the following molten steel vacuum processing containers (1) to (5).
(1) A molten steel vacuum processing container in which a ribboned magcro brick having an apparent porosity of 11.5% or less and a compressive strength of 115 MPa or more is disposed at a site where splash caused by oxygen blowing comes into contact.
(2) The molten steel vacuum processing container according to (1), wherein the content of ZrO 2 is 0.1% by mass or more and 5% by mass or less.
(3) The molten steel vacuum processing container according to (1), wherein the content of ZrO 2 is 0.5 mass% or more and 3 mass% or less.
(4) The ribboned magcro brick has an MgO content of 54% by mass to 75% by mass, a Cr 2 O 3 content of 19% by mass to 30% by mass, and MgO and Cr 2 O 3. The molten steel vacuum processing container according to (2) or (3), wherein the total amount of ZrO 2 is 86% by mass or more.
(5) The molten steel vacuum according to any one of (1) to (4), in which one or more of direct bond magcro bricks, semi-ribboned magcro bricks, and magnesia carbon bricks are disposed at a portion where the splash does not contact. Processing container.
なお、本発明において「酸素吹き込みに伴うスプラッシュが接触する部位」とは、概ね次のとおりである。すなわち、ＲＨ炉では槽底から上に２ｍ以下の側壁、ＤＨ炉では下端から上に３ｍ以下の側壁、ＶＯＤ炉では溶鋼面から上に１ｍ以下の側壁である。 In the present invention, the “site where the splash accompanying oxygen blowing contacts” is generally as follows. That is, in the RH furnace, the side wall is 2 m or less from the bottom of the tank, in the DH furnace, the side wall is 3 m or less from the lower end, and in the VOD furnace, the side wall is 1 m or less from the molten steel surface.
以下、本発明について詳しく説明する。 The present invention will be described in detail below.
マグクロれんがは緻密で高強度であるほど、溶鋼や酸化鉄などを主成分とするスプラッシュによって引き起こされる磨耗すなわち物理的な損耗、及び溶損すなわち化学的な損耗に対して損傷され難くなる。そこで本発明では、セミリボンドれんが及びダイレクトボンドれんがと比較して緻密で強度が高いリボンドれんが、なかでも見掛気孔率が１１．５％以下で圧縮強度が１１５ＭＰａのリボンドマグクロれんがを使用する。これは、見掛気孔率が１１．５％を超える、又は圧縮強度が１１５ＭＰａ未満の場合には、スプラッシュが当たる炉壁の局部損耗が大きくなるという本発明者等の知見に基づく。 The more dense and high-strength the magcro bricks are, the less likely they are to be damaged by wear or physical wear caused by splashes mainly composed of molten steel or iron oxide, and by melt or chemical wear. Therefore, in the present invention, a ribbon brick that is denser and higher in strength than semi-ribbon bricks and direct bond bricks is used, among which ribbon-magmag bricks having an apparent porosity of 11.5% or less and a compressive strength of 115 MPa are used. This is based on the knowledge of the present inventors that when the apparent porosity exceeds 11.5% or the compressive strength is less than 115 MPa, the local wear of the furnace wall hit by the splash increases.
また、本発明で使用するリボンドマグクロれんがは、スプラッシュによる耐溶損性を向上させるためにＺｒＯ２を含有することが好ましい。ＺｒＯ２の含有量は、０．１質量％以上５質量％以下であることが好ましく、０．５質量％以上３質量％以下であることがより好ましい。このようにＺｒＯ２を適量含有することで、れんが組織中に分布するＺｒＯ２がスプラッシュの主成分である酸化鉄と先行反応することでスプラッシュ（酸化鉄）の反応活性を失わせ、リボンドれんがの主成分であるＭｇＯの溶解を抑制させる。さらにＺｒＯ２を適量含有すると、リボンドマグクロれんがの組織を緻密化かつ高強度にすることができる。すなわち、酸性酸化物であるＺｒＯ２を塩基性酸化物であるＭｇＯを主成分とするマグクロれんがに原料として適量添加することにより、焼成中の焼結が促進される。これにより見掛気孔率の低減と圧縮強度の向上、つまり緻密高強度化の効果が得られる、 Moreover, it is preferable that the ribbon magcro brick used in the present invention contains ZrO 2 in order to improve the resistance to melting due to splash. The content of ZrO 2 is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less. By thus including an appropriate amount of ZrO 2, to lose the reactivity of splash (iron oxide) by ZrO 2 distributed in the brick structure is preceded react with the iron oxide which is the main component of the splash, the Ribondo brick The dissolution of MgO as the main component is suppressed. Further, when an appropriate amount of ZrO 2 is contained, the structure of the ribbon mag brick can be made dense and high in strength. That is, by adding an appropriate amount of ZrO 2 which is an acidic oxide as a raw material to a magcro brick mainly composed of MgO which is a basic oxide, sintering during firing is promoted. This reduces the apparent porosity and improves the compressive strength, that is, the effect of increasing the density and strength.
この緻密高強度化の効果は、マグクロれんがのなかでもリボンドれんがにおいて特に顕著に現れる。マグクロクリンカーと共にマグネシアクリンカーとクロム鉱を使用するセミリボンドれんがや、マグネシアクリンカーとクロム鉱を主原料とするダイレクトボンドれんがでは、クロム鉱の周囲にマグネシアクリンカーとの熱膨張係数の差に伴う長尺な空隙が形成されやすく、これがＺｒＯ２添加による緻密高強度化の効果を相殺してしまうためである。このため、ダイレクトボンドマグクロれんが及びセミリボンドマグクロれんがではＺｒＯ２を添加したとしても、リボンドれんがマグクロほどの見掛気孔率の低減と圧縮強度の向上は達成し難く、例えばＲＨ炉のスプラッシュが当たる炉壁に配置しても、十分な耐用性は得られない。 The effect of increasing the density and strength is particularly noticeable in ribbon bricks among magcro bricks. Semi-ribbon bricks that use magnesia clinker and chrome ore together with magcro clinker, and direct bond bricks that use magnesia clinker and chrome ore as the main raw material have long lengths due to the difference in thermal expansion coefficient between chrome ore and magnesia clinker. This is because voids are easily formed, which offsets the effect of increasing the density and strength by adding ZrO 2 . For this reason, even if ZrO 2 is added to direct bond magcro bricks and semi-ribboned magcro bricks, it is difficult to reduce the apparent porosity and increase the compressive strength as in ribbon bricks. Even if it is placed on the furnace wall that hits, sufficient durability cannot be obtained.
また、リボンドマグクロれんがの組織を緻密化かつ高強度化するためには、れんが中のＭｇＯとＣｒ２Ｏ３の含有量を特定範囲とすることも有効である。具体的には、ＭｇＯの含有量は５４質量％以上７５質量％以上、Ｃｒ２Ｏ３の含有量は１９質量％以上３０質量％以上であることが好ましい。ＭｇＯの含有量が５４質量％未満では、焼成時に気孔の集約化が進み過ぎて粗大化するため見掛気孔率の上昇と圧縮強度の低下を招きやすい。また、ＭｇＯの含有量が７５質量％を超えると焼成時に気孔の集約化が不十分となり、見掛気孔率の上昇と圧縮強度の低下を招きやすい。一方、Ｃｒ２Ｏ３の含有量が１９質量％未満では、必然的にＭｇＯの含有量が７５質量％を超えるため焼成時に気孔の集約化が不十分となり、見掛気孔率の上昇と圧縮強度の低下を招きやすい。また、Ｃｒ２Ｏ３の含有量が３０質量％を超えると、必然的にＭｇＯが５４質量％未満となるため、焼成時に気孔の集約化が進み過ぎて粗大化するため見掛気孔率の上昇と圧縮強度の低下を招きやすい。 In addition, in order to increase the density and strength of the ribboned magcro brick, it is also effective to set the contents of MgO and Cr 2 O 3 in the brick within a specific range. Specifically, the MgO content is preferably 54% by mass or more and 75% by mass or more, and the Cr 2 O 3 content is preferably 19% by mass or more and 30% by mass or more. If the content of MgO is less than 54% by mass, the pores are excessively aggregated and coarsened during firing, so that the apparent porosity is likely to increase and the compressive strength is likely to decrease. On the other hand, when the content of MgO exceeds 75% by mass, the pores are not sufficiently aggregated during firing, and the apparent porosity and the compressive strength are liable to be increased. On the other hand, if the content of Cr 2 O 3 is less than 19% by mass, the content of MgO inevitably exceeds 75% by mass, resulting in insufficient pore concentration during firing, and an increase in apparent porosity and compressive strength. It is easy to invite a decline. Further, if the content of Cr 2 O 3 exceeds 30% by mass, MgO inevitably becomes less than 54% by mass, so that the pores are excessively concentrated during firing and the apparent porosity is increased. It tends to cause a decrease in compression strength.
なお、本発明の溶鋼真空処理容器においてスプラッシュが接触しない部位には、損耗速度が小さいため本発明によるリボンドマグクロれんがを使用しなくても良く、むしろこれらの部位では温度変動の大きい溶鋼真空処理容器本来の損傷形態である熱的スポーリングによる剥離損耗がより支配的となるため、比較的耐スポール性に優れているダイレクトボンドマグクロれんが、セミリボンドマグクロれんが及びマグネシアカーボンれんがのうち１種以上を配置することが好ましい。 In the molten steel vacuum processing vessel of the present invention, the portion where the splash does not contact does not need to use the ribboned magcro brick according to the present invention because the wear rate is small. Because the debonding wear due to thermal spalling, which is the original form of damage to processing containers, becomes more dominant, direct bond magcro bricks, which are relatively excellent in spall resistance, are semi-ribboned magcro bricks and magnesia carbon bricks. It is preferable to arrange one or more kinds.
本発明によれば、溶鋼真空処理容器においてスプラッシュが接触することで局部損耗が発生する部位に、見掛け気孔率が１１．５％以下で圧縮強度が１１５ＭＰａ以上という緻密で高強度のリボンドマグクロれんがを配置することで、局部損耗が抑制されて、溶鋼真空処理容器全体が均一的な損耗プロフィールとなり、その結果として溶鋼真空処理容器の寿命延長が達成できる。 According to the present invention, in a molten steel vacuum processing vessel, a portion where local wear occurs due to splash contact is a dense and high-strength ribbon-coated magchrom with an apparent porosity of 11.5% or less and a compressive strength of 115 MPa or more. By arranging the brick, local wear is suppressed, and the entire molten steel vacuum processing vessel has a uniform wear profile. As a result, the life extension of the molten steel vacuum processing vessel can be achieved.
本発明を適用する溶鋼真空処理容器は、典型的にはＲＨ炉、ＤＨ炉及びＶＯＤ炉であって、真空槽内の溶鋼面上から酸素ガスを吹き付ける酸素処理を行う炉である。例えば、ＲＨ炉としては、溶鋼を吸い上げて真空脱炭処理しながら真空槽の上部から挿入された上吹きランスによって酸素ガスを溶鋼表面に吹き付ける酸素処理を行うＲＨ炉に本発明を好適に適用することができる。また、ＤＨ炉では、溶鋼を吸い上げて真空脱炭処理する際に、取鍋の底部に設置されたポーラスプラグによるバブリングにより溶鋼を攪拌する。これにより真空槽内には、下から上に向かって溶鋼面に到達し、さらに上から下に向かって降りて行く強力な流れが形成される。このとき溶鋼面上からはＲＨ炉と同様に酸素ガスを吹き付けるため多量のスプラッシュが飛散し、真空槽内壁面を局部損傷させるため、本発明を好適に適用することができる。また、ＶＯＤ炉もＲＨ炉と同様に、溶鋼面上に酸素ガスや粉体を吹き付ける処理を行い、かつＤＨ炉と同様に底部に設置されたポーラスプラグによるバブリングにより溶鋼を攪拌も実施するので、溶鋼面上のスプラッシュが接触する部位に局部損耗が発生することから、本発明を好適に適用することができる。 The molten steel vacuum processing vessel to which the present invention is applied is typically a RH furnace, a DH furnace, and a VOD furnace, and performs an oxygen treatment in which oxygen gas is blown from above the molten steel surface in the vacuum chamber. For example, as the RH furnace, the present invention is preferably applied to an RH furnace that performs oxygen treatment in which oxygen gas is blown onto the surface of the molten steel by an upper blowing lance inserted from the upper part of the vacuum tank while sucking up the molten steel and performing vacuum decarburization treatment. be able to. In the DH furnace, when the molten steel is sucked up and vacuum decarburized, the molten steel is stirred by bubbling with a porous plug installed at the bottom of the ladle. As a result, a strong flow is formed in the vacuum chamber that reaches the molten steel surface from the bottom to the top and further descends from the top to the bottom. At this time, since oxygen gas is blown from the surface of the molten steel in the same manner as in the RH furnace, a large amount of splash is scattered and the inner wall surface of the vacuum chamber is locally damaged, so that the present invention can be suitably applied. Also, the VOD furnace, like the RH furnace, performs a process of spraying oxygen gas or powder onto the molten steel surface, and also stirs the molten steel by bubbling with a porous plug installed at the bottom like the DH furnace. Since local wear occurs at the site where the splash on the molten steel contacts, the present invention can be suitably applied.
本発明の溶鋼真空処理容器においてスプラッシュが接触する部位に配置するれんがは、前述のとおり、見掛気孔率が１１．５％以下で圧縮強度が１１５ＭＰａ以上のリボンドマグクロれんがである。このように緻密で高強度のリボンドマグクロれんがは、従来のリボンドマグクロれんがの製造条件に比べ高圧で成形したり、高温で成形したりすることで得ることができるが、従来のリボンドマグクロれんがにＺｒＯ２を０．１質量％以上５質量％以下添加することで製造条件をほとんど変更せずに得ることもできる。ＺｒＯ２源としては、電融ジルコニア、焼結ジルコニア、バデライトなどが挙げられ、ＣａＯやＭｇＯで安定化したものも使用可能である。 As described above, the brick disposed at the site where the splash contacts in the molten steel vacuum processing container of the present invention is a ribbon-type magcro brick having an apparent porosity of 11.5% or less and a compressive strength of 115 MPa or more. In this way, a dense and high-strength ribbon magcro brick can be obtained by molding at a higher pressure or at a higher temperature than conventional ribbon mag bricks. By adding ZrO 2 in an amount of 0.1% by mass or more and 5% by mass or less to domagcro bricks, it can be obtained with almost no change in production conditions. Examples of the ZrO 2 source include electrofused zirconia, sintered zirconia, and baderite, and those stabilized with CaO or MgO can also be used.
このように本発明で使用するリボンドマグクロれんがは、典型的には、電融マグクロクリンカー、酸化クロム、及びジルコニア（ＺｒＯ２源）からなる原料配合にバインダーを添加して混練後、成形し、１７５０℃〜１８５０℃で焼成することで得ることができる。なお、このリボンドマグクロれんがの製造においては、その原料として５質量％以下のマグネシア及び／又は５質量％以下のクロム鉱を合量で５質量％以下であれば使用しても悪影響を及ぼさないため許容できる。 As described above, the ribbon mag brick used in the present invention is typically molded after kneading by adding a binder to a raw material composition composed of an electrofused mag crocliner, chromium oxide, and zirconia (ZrO 2 source). And it can obtain by baking at 1750 degreeC-1850 degreeC. In the production of this ribbon mag brick, even if 5 mass% or less magnesia and / or 5 mass% or less chromium ore is used as a raw material in a total amount of 5 mass% or less, there is an adverse effect. Not acceptable.
表１は、本発明の実施例によるリボンドマグクロれんがの原料配合とその物性及び化学成分を比較例とともに示したものである。この表１の原料配合にバインダーを添加して混練後、成形し、１７５０℃以上で焼成することでそれぞれリボンドマグクロれんがを得た。表１中の各電融マグクロクリンカーの化学成分は表２に示したとおりである。また、酸化クロムは純度９９％のものを、ジルコニアは純度９９％のものをそれぞれ使用した。 Table 1 shows the raw material composition of the ribbon magcro brick according to the example of the present invention, its physical properties and chemical components together with comparative examples. A binder was added to the raw material composition shown in Table 1, kneaded, molded, and fired at 1750 ° C. or higher to obtain ribboned magcro bricks. The chemical components of each electrofused magclocliner in Table 1 are as shown in Table 2. Further, chromium oxide having a purity of 99% and zirconia having a purity of 99% were used.
得られたマグクロれんがからサンプルを切り出して物性と化学成分を測定した。物性として、見掛比重、かさ比重及び見掛気孔率はＪＩＳ−Ｒ２２０５、圧縮強さはＪＩＳ−Ｒ２２０６に従い測定した。また化学成分はＪＩＳ−Ｒ２２１２に従い測定した。 A sample was cut out from the obtained magcro brick and the physical properties and chemical components were measured. As physical properties, the apparent specific gravity, bulk specific gravity and apparent porosity were measured according to JIS-R2205, and the compressive strength was measured according to JIS-R2206. The chemical component was measured according to JIS-R2212.
表１においてＮｏ.１からＮｏ.７は、見掛気孔率及び圧縮強度が本発明の範囲内にある実施例である。一方、Ｎｏ.８は、ジルコニアを添加しておらず見掛気孔率が高くなっている。Ｎｏ.９は、ジルコニアの添加量が過剰で見掛気孔率が高くなっている。Ｎｏ.１０は、クロム鉱を添加したもので見掛気孔率が高くなっている。Ｎｏ.１１は、クロム鉱と海水マグネシアを含有するためジルコニアを添加しても見掛気孔率が高くなっている。このように、Ｎｏ.８からＮｏ.１１はいずれも見掛気孔率が高く、また圧縮強度は低く、本発明の範囲外の比較例である。 In Table 1, No. 1 to No. 7 are examples in which the apparent porosity and compressive strength are within the scope of the present invention. On the other hand, No. 8 does not contain zirconia and has a high apparent porosity. In No. 9, the added amount of zirconia is excessive and the apparent porosity is high. No. 10 has added chromium ore and has a high apparent porosity. No. 11 contains chromium ore and seawater magnesia, so the apparent porosity is high even when zirconia is added. Thus, all of No. 8 to No. 11 have high apparent porosity and low compressive strength, and are comparative examples outside the scope of the present invention.
表１に示すリボンドマグクロれんがのうち、Ｎｏ.４，５，６，８，９をＯＢ処理を行うＲＨ炉の炉壁に配置して使用した。具体的には、炉底から６段目から１０段目まで（炉底から上に１ｍ以上１．８ｍ以下の間）にライニングして実炉で使用した。酸素処理条件は流量０．２Ｎｍ３／ｍｉｎ、処理時間１５分とした。途中で損耗状況を観察しながら鉄皮とパーマれんがの境界に配置した熱電対の数値が所定の温度になるまで使用し、使用回数を表１に示した。 Of the ribboned magcro bricks shown in Table 1, Nos. 4, 5, 6, 8, and 9 were used by being arranged on the furnace wall of the RH furnace that performs the OB treatment. Specifically, it was lined from the 6th stage to the 10th stage from the furnace bottom (between 1 m and 1.8 m above the furnace bottom) and used in an actual furnace. The oxygen treatment conditions were a flow rate of 0.2 Nm 3 / min and a treatment time of 15 minutes. The number of times of use is shown in Table 1 until the numerical value of the thermocouple arranged at the boundary between the iron skin and the perma brick reaches a predetermined temperature while observing the wear state on the way.
見掛気孔率と圧縮強度が本発明の範囲内のＮｏ.４，５及び６は、使用回数が２５０回以上と多いが、見掛け気孔率と圧縮強度が本発明の範囲外のＮｏ.８及び９は使用回数がそれぞれ１８０回と１９５回と劣る結果となった。 Nos. 4, 5 and 6 whose apparent porosity and compressive strength are within the range of the present invention are used as many as 250 times or more, but the apparent porosity and compressive strength are No. 8 and 9 was inferior to 180 and 195 times.
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