JP5068887B1 - Vacuum degassing tank and degassing treatment method using the same - Google Patents
Vacuum degassing tank and degassing treatment method using the same Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
- C04B35/04—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on magnesium oxide
- C04B35/043—Refractories from grain sized mixtures
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D1/00—Casings; Linings; Walls; Roofs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D1/00—Casings; Linings; Walls; Roofs
- F27D1/0003—Linings or walls
- F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/40—Metallic constituents or additives not added as binding phase
- C04B2235/401—Alkaline earth metals
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/40—Metallic constituents or additives not added as binding phase
- C04B2235/402—Aluminium
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/42—Non metallic elements added as constituents or additives, e.g. sulfur, phosphor, selenium or tellurium
- C04B2235/422—Carbon
- C04B2235/425—Graphite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B7/00—Blast furnaces
- C21B7/04—Blast furnaces with special refractories
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/42—Constructional features of converters
- C21C5/44—Refractory linings
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- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
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- Mechanical Engineering (AREA)
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- Compositions Of Oxide Ceramics (AREA)
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Abstract
この真空脱ガス槽では：耐火物のうちの少なくとも溶融スラグとの接触部分に、炭素含有マグネシア質耐火物が設けられ；前記炭素含有マグネシア質耐火物は、７質量％以上かつ２８％未満の黒鉛と、３．５質量％以上かつ１４質量％以下のＡｌ−Ｍｇ合金とを有してかつ、残部がマグネシア及び不可避的不純物からなり、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５以上２．０以下である。
【選択図】図２ＡIn this vacuum degassing tank: a carbon-containing magnesia refractory is provided at least in contact with molten slag among the refractories; the carbon-containing magnesia refractory is not less than 7% by mass and less than 28% graphite. And an Al—Mg alloy of 3.5% by mass or more and 14% by mass or less and the balance is magnesia and inevitable impurities, and the mass of the Al—Mg alloy is divided by the mass of the graphite. The mass ratio is 0.5 or more and 2.0 or less.
[Selection] Figure 2A
Description
この発明は、低塩基度スラグに対して優れた耐用性を有する真空脱ガス槽と、この真空脱ガス槽を用いた脱ガス処理方法とに関する。 The present invention relates to a vacuum degassing tank having excellent durability against low basicity slag and a degassing treatment method using the vacuum degassing tank.
真空脱ガス装置に用いられる真空脱ガス槽には、マグネシアカーボンれんがやマグネシアクロミアれんがのような耐火物が使用されている。この耐火物としては、耐熱衝撃性に優れることから、マグネシアカーボンれんが等の炭素含有耐火物が広く使用されている。 Refractories such as magnesia carbon bricks and magnesia chromia bricks are used in vacuum degassing tanks used in vacuum degassing apparatuses. As this refractory, a carbon-containing refractory such as magnesia carbon brick is widely used because of its excellent thermal shock resistance.
炭素含有耐火物は、高温での耐酸化性に弱点を有する炭素を含むことから、強い酸化性雰囲気下では溶損速度が増大してしまう。そこで、炭素含有耐火物にＡｌ粉末、Ａｌ−Ｓｉ合金粉末、Ａｌ−Ｍｇ合金粉末等の酸化防止剤を添加することが、従来より行われている（例えば特許文献１〜５、１０、１１参照）。これは、高温下における酸素親和力が炭素よりも大きい金属粉末を添加することで、炭素が酸化されるのを防ぐことを目的としている。 Since a carbon-containing refractory contains carbon having a weak point in oxidation resistance at high temperatures, the rate of erosion increases in a strong oxidizing atmosphere. Then, adding antioxidants, such as Al powder, Al-Si alloy powder, and Al-Mg alloy powder, to a carbon-containing refractory has been conventionally performed (see, for example, Patent Documents 1 to 5, 10, and 11). ). This is intended to prevent carbon from being oxidized by adding a metal powder having a higher oxygen affinity than carbon at high temperatures.
ところが、マグネシアカーボンれんがは、スラグ塩基度（ＣａＯ／ＳｉＯ２：以下、単に塩基度もしくは「Ｃ／Ｓ」と言う場合がある）が３前後又はこれよりも高いスラグに対して良好な耐用を示すものの、塩基度がこれよりも低いスラグに対しては、耐用性が劣る。これは、塩基度が低いスラグは、粘性がかなり低下するため、スラグがれんがの内部に浸透してマグネシア骨材が溶損したり、スポーリングを起こしたりてしまうためである。そこで、アルミニウム合金粉末の他に、金属クロム又はクロム化合物を含有させることで、酸化したＣｒ２Ｏ３がれんがの稼動表面とスラグとの反応層中でＭｇＯ−Ｃｒ２Ｏ３系の高融点物を生成し、スラグの見掛けの粘性を高めて、マグネシア骨材の溶出を抑える方法が提案されている（特許文献６参照）。また、同様に、アルミニウム合金粉末の他に、ジルコン酸カルシウムを含有させることで、高温で解離したＣａＯがスラグに溶け込み、スラグの粘性を上げて浸透を抑制する方法や（特許文献７参照）、環境への影響を考慮して、クロムを使用せずに、希土類酸化物を含有させることで、希土類酸化物がスラグ中のＳｉＯ２と反応してスラグの融点を上昇させて、浸透を抑制させる方法（特許文献８参照）などが提案されている。更には、スラグの塩基度に応じて、スラグ中にＭｇＯを主成分とするれんがの破砕物やＡｌを添加することで、スラグ成分をＭｇＯの初晶域となるように調整してスラグを改質する方法も提案されている（特許文献９参照）。However, magnesia carbon bricks exhibit good durability against slag whose slag basicity (CaO / SiO 2 : hereinafter, sometimes simply referred to as basicity or “C / S”) is around 3 or higher. However, durability is inferior to slag having a lower basicity. This is because slag with low basicity has a considerably reduced viscosity, so that the slag penetrates into the brick and the magnesia aggregate melts or spalls. Therefore, in addition to the aluminum alloy powder, by containing metal chromium or a chromium compound, a high melting point material of MgO—Cr 2 O 3 system in the reaction layer between the working surface of the oxidized Cr 2 O 3 brick and the slag. Has been proposed to increase the apparent viscosity of slag and suppress the dissolution of magnesia aggregate (see Patent Document 6). Similarly, in addition to aluminum alloy powder, by containing calcium zirconate, CaO dissociated at a high temperature dissolves in slag, and increases the viscosity of slag to suppress permeation (see Patent Document 7). Considering the environmental impact, the rare earth oxide reacts with the SiO 2 in the slag to increase the melting point of the slag and suppress the permeation by including the rare earth oxide without using chromium. A method (see Patent Document 8) has been proposed. Furthermore, depending on the basicity of the slag, the slag can be adjusted so that the slag component is in the primary crystal region of MgO by adding crushed bricks mainly composed of MgO or Al into the slag. A method of quality improvement has also been proposed (see Patent Document 9).
なお、特許文献１０には、Ａｌ−Ｍｇ合金を添加したマグネシアカーボンれんがが記載されているが、これは本文中の記載設備および耐蝕テストの試験条件のスラグ塩基度（Ｃ／Ｓ）が３であることから明らかなように、転炉にて使用した場合を模擬した結果である。 Patent Document 10 describes a magnesia carbon brick to which an Al—Mg alloy is added. This is because the slag basicity (C / S) of the test equipment for the described equipment and corrosion resistance test in the text is 3. As is clear from the fact, it is a result of simulating the case where it is used in a converter.
また、特許文献１１には、溶射補修に適したマグネシアカーボンれんがとして、固定炭素量が１３質量％以下で、Ａｌ粉やＡｌ−Ｍｇ合金をＡｌ含有量で３質量％以下になるように添加した例が記載されている。しかしながら、この特許文献１１の背景技術、発明が解決しようとする課題には、この発明を転炉で使用することと明記されており、耐食性評価方法も、転炉スラグを用いて評価するなど、本発明が対象としている低塩基度スラグによる耐用性は示されていない。 In addition, in Patent Document 11, as magnesia carbon brick suitable for thermal spray repair, the amount of fixed carbon is 13 mass% or less, and Al powder or Al-Mg alloy is added so that the Al content is 3 mass% or less. An example is given. However, in the background art of this patent document 11, the problem to be solved by the invention is clearly stated that this invention is used in a converter, and the corrosion resistance evaluation method is also evaluated using a converter slag. The durability of the low basicity slag targeted by the present invention is not shown.
よって、従来、真空脱ガス槽に用いるマグネシアカーボンれんがにおけるＡｌ−Ｍｇ合金添加は、黒鉛の酸化防止のために少量添加することが知られていたものの、低塩基度スラグに対する耐用性については判っていなかった。 Therefore, conventionally, Al-Mg alloy addition to magnesia carbon brick used in vacuum degassing tanks has been known to be added in a small amount to prevent oxidation of graphite, but the durability against low basicity slag is known. There wasn't.
しかしながら、低塩基度スラグに対するマグネシアカーボンれんがの耐用は、未だ十分であるとは言えず、例えば、真空脱ガス槽を用いて、Ａｌ−Ｓｉ−ｋｉｌｌｅｄ鋼、Ｓｉ−ｋｉｌｌｅｄ鋼、Ｓｉ添加鋼等を溶製するような場合には、塩基度が２以下の低塩基度スラグが発生するため、真空脱ガス処理中の真空脱ガス槽の内張り耐火物が激しく損耗してしまう。 However, the durability of magnesia carbon bricks against low basicity slag is still not sufficient. For example, using a vacuum degassing tank, Al-Si-killed steel, Si-killed steel, Si-added steel, etc. In the case of melting, low basicity slag having a basicity of 2 or less is generated, so that the refractory lining the vacuum degassing tank during the vacuum degassing process is severely worn.
そこで、本発明者らは、このような問題を解決するために鋭意検討した結果、真空脱ガス槽用の炭素含有マグネシア質耐火物におけるＡｌ−Ｍｇ合金や黒鉛の含有量について詳細な検討を行う過程で、新たな知見を得た。すなわち、従来、炭素より早い親和性によって炭素の酸化を防止するような酸化防止剤として使われていたＡｌ−Ｍｇ合金が、驚くべきことには、その含有量をある特定の範囲にすると共に、耐火物中の黒鉛に対する質量比を従来よりも極めて高く設定することで、マグネシア骨材の溶損を抑える働きを発現して、上記のような低塩基度スラグに対しても優れた耐用性を示すことができることを見出した。また、従来からＡｌ−Ｍｇ合金をはじめとする金属の含有量が増加すると（例えば３質量％以上）、耐熱衝撃性が低くなることが知られていたが、本発明者らは、黒鉛をＡｌ−Ｍｇ合金含有量に対してある質量比の範囲とすることで耐熱衝撃性も確保が可能であることを見出し、本発明を完成した。 Therefore, as a result of intensive studies to solve such problems, the present inventors conduct a detailed study on the content of Al—Mg alloy and graphite in carbon-containing magnesia refractories for vacuum degassing tanks. In the process, I gained new knowledge. That is, the Al-Mg alloy that has been used as an antioxidant to prevent the oxidation of carbon with an affinity earlier than that of carbon is surprisingly made its content within a certain range, By setting the mass ratio of graphite in the refractory to be extremely higher than before, it exerts a function to suppress the melting damage of magnesia aggregate, and has excellent durability against low basicity slag as described above. Found that can be shown. Further, it has been conventionally known that when the content of metals such as Al—Mg alloys increases (for example, 3% by mass or more), the thermal shock resistance is lowered. The inventors have found that the thermal shock resistance can be secured by setting the mass ratio within a certain range relative to the Mg alloy content, and the present invention has been completed.
したがって、本発明は、塩基度（Ｃ／Ｓ）が２以下となるような低塩基度スラグに対して優れた耐用性を示す炭素含有マグネシア質耐火物をライニングした真空脱ガス槽の提供を目的とする。 Accordingly, an object of the present invention is to provide a vacuum degassing tank lined with a carbon-containing magnesia refractory exhibiting excellent durability against low basicity slag having a basicity (C / S) of 2 or less. And
また、本発明は、Ｓｉ源を添加して鋼の二次精錬を行う脱ガス処理方法において、真空脱ガス槽の損耗を可及的に抑えて脱ガス処理を行うことができる脱ガス処理方法の提供を他の目的とする。 Further, the present invention relates to a degassing method for performing secondary gasification of steel by adding a Si source, and capable of performing degassing processing while suppressing wear of the vacuum degassing tank as much as possible. For other purposes.
本発明は、上記課題を解決して係る目的を達成するために以下を採用した。
（ａ）本発明の一態様は、鉄皮と、この鉄皮の内部を覆う耐火物とを備え、減圧雰囲気でＣａＯ／ＳｉＯ２≦２の低塩基度スラグが生成するような溶鋼の脱ガス処理に用いる真空脱ガス槽であって、前記耐火物のうちの少なくとも溶融スラグとの接触部分に、炭素含有マグネシア質耐火物が設けられ；前記炭素含有マグネシア質耐火物は、７質量％以上かつ２８％未満の黒鉛と、７質量％以上かつ１４質量％以下のＡｌ−Ｍｇ合金とを有してかつ、残部がマグネシア及び不可避的不純物からなり、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５以上２．０以下である。
（ｂ）上記（ａ）に記載の真空脱ガス槽では、前記質量比の下限値が１．０であってもよい。
The present invention employs the following in order to solve the above problems and achieve the object.
(A) One aspect of the present invention includes an iron skin and a refractory material covering the inside of the iron skin, and degassing molten steel such that a low basicity slag of CaO / SiO 2 ≦ 2 is generated in a reduced-pressure atmosphere. A vacuum degassing tank used for processing, wherein a carbon-containing magnesia refractory is provided at least in contact with the molten slag in the refractory; the carbon-containing magnesia refractory is 7% by mass or more and It has less than 28% graphite and 7 % by mass or more and 14% by mass or less Al—Mg alloy, and the balance consists of magnesia and inevitable impurities, and the mass of the Al—Mg alloy is the mass of the graphite. The mass ratio divided by is 0.5 or more and 2.0 or less.
(B) In the vacuum degassing tank described in (a) above, the lower limit of the mass ratio may be 1.0.
（ｃ）本発明の一態様に係る真空脱ガス処理方法は、鉄皮と、この鉄皮の内部を覆う耐火物とを備えた真空脱ガス槽を用いて、減圧雰囲気でＣａＯ／ＳｉＯ２≦２の低塩基度スラグが生成するような溶鋼の脱ガス処理を行う真空脱ガス処理方法であって、前記真空脱ガス槽は、前記耐火物のうちの少なくとも溶融スラグとの接触部分に、炭素含有マグネシア質耐火物が設けられ；前記炭素含有マグネシア質耐火物は、７質量％以上かつ２８％未満の黒鉛と、３．５質量％以上かつ１４質量％以下のＡｌ−Ｍｇ合金とを有してかつ、残部がマグネシア及び不可避的不純物からなり、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５以上２．０以下である。
（ｄ）上記（ｃ）に記載の真空脱ガス処理方法では、前記真空脱ガス槽中にＳｉ又はＳｉ合金を添加して鋼の二次精錬を行いながら、前記真空脱ガス処理を行ってもよい。
(C) A vacuum degassing treatment method according to one embodiment of the present invention uses a vacuum degassing tank including an iron skin and a refractory material covering the inside of the iron skin, and in a reduced pressure atmosphere, CaO / SiO 2 ≦ 2 is a vacuum degassing method for degassing molten steel so that low-basicity slag of 2 is generated , wherein the vacuum degassing tank has carbon at least in contact with the molten slag in the refractory. Containing magnesia refractory is provided; the carbon-containing magnesia refractory has 7% by mass or more and less than 28% graphite, and 3.5% by mass or more and 14% by mass or less Al-Mg alloy. The balance is made of magnesia and inevitable impurities, and the mass ratio obtained by dividing the mass of the Al—Mg alloy by the mass of the graphite is 0.5 or more and 2.0 or less .
(D) In the vacuum degassing method described in (c) above, even if the vacuum degassing treatment is performed while performing secondary refining of steel by adding Si or an Si alloy to the vacuum degassing tank. Good.
本発明の上記態様に係る真空脱ガス槽に用いる炭素含有マグネシア質耐火物は、Ａｌ−Ｍｇ合金を内掛けで３．５質量％〜１４質量％含有するのが好ましく、より好ましくは３．５〜１０．５質量％含有するのが良い。Ａｌ−Ｍｇ合金の含有量が３．５質量％に満たないと、所望の耐食性を確保することができず、反対に１４質量％を超えて含有すると、使用中に炭素含有マグネシア質耐火物の気孔率が上昇し、組織が脆弱化するため、やはり耐食性が低下する。Ａｌ−Ｍｇ合金の種類については特に制限されず、マグネシアカーボンれんがに酸化防止剤として添加される一般的なものを使用することができるが、好適には、Ａｌ１２Ｍｇ１７の組成からなる合金を用いるのが良い。また、粒径が４０μｍ〜２００μｍのＡｌ−Ｍｇ合金を用いるのが良い。The carbon-containing magnesia refractory used in the vacuum degassing tank according to the above aspect of the present invention preferably contains 3.5% by mass to 14% by mass of an Al—Mg alloy, more preferably 3.5%. It is good to contain ~ 10.5 mass%. If the content of the Al-Mg alloy is less than 3.5% by mass, the desired corrosion resistance cannot be ensured. Conversely, if the content exceeds 14% by mass, the carbon-containing magnesia refractory is in use. Since the porosity increases and the tissue becomes brittle, the corrosion resistance is also lowered. The type of the Al—Mg alloy is not particularly limited, and a general one added as an antioxidant to the magnesia carbon brick can be used. Preferably, an alloy having a composition of Al 12 Mg 17 is used. It is good to use. Moreover, it is good to use the Al-Mg alloy whose particle size is 40 micrometers-200 micrometers.
また、上記態様に係る真空脱ガス槽に用いる炭素含有マグネシア質耐火物に含まれる黒鉛は、一般に、マグネシアカーボンれんがに含まれるものと同様のものを使用することができる。例えば、鱗状黒鉛、土状黒鉛、人造黒鉛、膨張黒鉛等が挙げられるが、好適には、結晶の良く発達した天然の鱗状黒鉛を用いるのが良い。黒鉛の含有量については、内掛けで７質量％以上であるのが良く、好ましくは７質量％〜２８質量％、より好ましくは７質量％〜１４質量％であるのが良い。黒鉛の含有量が７質量％に満たないと、いわゆる炭素含有マグネシア質耐火物として機能するための炭素の役割を十分に果たすことができない。黒鉛の含有量が２８質量％を超えると、成型が困難になり、耐火物としての充填性が確保できなくなる。黒鉛の含有量が１４質量％以下であれば、より充填性が良好となる。 The graphite contained in the carbon-containing magnesia refractory used in the vacuum degassing tank according to the above aspect can generally be the same as that contained in the magnesia carbon brick. For example, scaly graphite, earthy graphite, artificial graphite, expanded graphite, and the like can be mentioned. Naturally scaly graphite having a well-developed crystal is preferably used. The graphite content is preferably 7% by mass or more as an inner layer, preferably 7% to 28% by mass, more preferably 7% to 14% by mass. If the content of graphite is less than 7% by mass, the role of carbon for functioning as a so-called carbon-containing magnesia refractory cannot be sufficiently achieved. When the content of graphite exceeds 28% by mass, molding becomes difficult, and the filling property as a refractory cannot be secured. If the graphite content is 14% by mass or less, the filling property becomes better.
そして、上記態様においては、上記Ａｌ−Ｍｇ合金と黒鉛との質量比（Ａｌ−Ｍｇ合金／黒鉛）が０．５以上、好ましくは１．０以上、より好ましくは１．０〜２．０の範囲内になるようにする。従来のマグネシアカーボンれんがにおいては、溶融スラグに濡れにくい黒鉛が稼動面に残存することで、溶融スラグによる湿潤を防ぐことができるが、ＲＨ（Ｒｕｈｒｓｔａｈｌ−Ｈｅｒａｕｓ）やＤＨ（Ｄｏｒｔｍｕｎｔ−Ｈｏｒｄｅ）等の真空脱ガス装置による減圧下の脱ガス処理では、マグネシアカーボンれんがのＭｇＯ骨材とＣとの間で、下式（１）のような化学反応が進行して、れんがが揮発するおそれがある。
ＭｇＯ（ｓ）＋Ｃ（ｓ）→Ｍｇ（ｇ）↑＋ＣＯ（ｇ）↑ ・・・（１）And in the said aspect, mass ratio (Al-Mg alloy / graphite) of the said Al-Mg alloy and graphite is 0.5 or more, Preferably it is 1.0 or more, More preferably, it is 1.0-2.0. Try to be within range. In conventional magnesia carbon bricks, graphite that is difficult to wet with molten slag remains on the working surface, so that wetting can be prevented by molten slag. In the degassing treatment under reduced pressure by the degassing apparatus, the chemical reaction as expressed by the following formula (1) may proceed between the MgO aggregate of C and the C, and the brick may be volatilized.
MgO (s) + C (s) → Mg (g) ↑ + CO (g) ↑ (1)
そこで、上記態様では、Ａｌ−Ｍｇ合金を上述した範囲で含有させると共に、Ａｌ−Ｍｇ合金と黒鉛との質量比（Ａｌ−Ｍｇ合金／黒鉛）を０．５以上にすることで、炭素含有マグネシア質耐火物中のＭｇ分圧を高めて、上式（１）の反応を抑制してＭｇＯ骨材の溶損を防止する。この質量比の上限については、Ａｌ−Ｍｇ合金の添加量を増加しすぎると耐火物に過焼結による亀裂が発生することから、Ａｌ−Ｍｇ合金／黒鉛の質量比を２．０以下とするのが良い。このような上記態様の炭素含有マグネシア質耐火物を真空脱ガス槽の内張り耐火物に用いれば、例えばＡｌ−Ｓｉ−ｋｉｌｌｅｄ鋼、Ｓｉ−ｋｉｌｌｅｄ鋼、Ｓｉ添加鋼等の溶製のように、Ｓｉ又はＳｉ合金を添加しながらＣａＯ／ＳｉＯ２≦２の低塩基度スラグが生成する鋼の二次精錬においても、真空脱ガス槽の損耗を可及的に抑えて、好適に脱ガス処理を行うことができる。Therefore, in the above embodiment, the Al—Mg alloy is contained in the above-described range, and the mass ratio of Al—Mg alloy to graphite (Al—Mg alloy / graphite) is set to 0.5 or more, so that the carbon-containing magnesia The Mg partial pressure in the refractory material is increased to suppress the reaction of the above formula (1) and prevent the MgO aggregate from being damaged. About the upper limit of this mass ratio, if the amount of Al-Mg alloy added is increased too much, cracks due to oversintering occur in the refractory, so the mass ratio of Al-Mg alloy / graphite should be 2.0 or less. Is good. If the carbon-containing magnesia refractory having the above-described aspect is used as a lining refractory for a vacuum degassing tank, for example, Al-Si-killed steel, Si-killed steel, Si-added steel, etc. Or, in the secondary refining of steel in which low basicity slag of CaO / SiO 2 ≦ 2 is generated while adding Si alloy, wear of the vacuum degassing tank is suppressed as much as possible, and degassing treatment is suitably performed. be able to.
上記態様の真空脱ガス槽に用いる炭素含有マグネシア質耐火物に含まれるマグネシアは、一般に耐火物の骨材として使用されるものであればよく、例えば、天然マグネサイトを焼成した天然マグネシア等の焼結マグネシアや、マグネシア原料を電気炉で溶融して再結晶させた電融マグネシア等を用いることができる。これらのマグネシア骨材は、３〜５ｍｍ程度もしくはそれ以下に粉砕して粒度を調整したものを用いるのが一般的であるが、特に制限はされない。また、マグネシアの含有量については、黒鉛、及びＡｌ−Ｍｇ合金の他、後述するバインダー樹脂や、本発明の目的から外れない範囲で配合してもよい添加物を含めて、これらの配合成分を除いて、耐火物原料の残部としてマグネシアの配合量と設定すればよく、好ましくは、内掛けで５６質量％以上含有されるのが良い。 The magnesia contained in the carbon-containing magnesia refractory used in the vacuum degassing tank of the above-described embodiment is not limited as long as it is generally used as an aggregate of a refractory. For example, fused magnesia or electrofused magnesia obtained by melting and recrystallizing a magnesia raw material in an electric furnace can be used. These magnesia aggregates are generally used with a particle size adjusted to about 3 to 5 mm or less, but are not particularly limited. As for the content of magnesia, in addition to graphite and Al—Mg alloy, these compounding components are included, including binder resins described later, and additives that may be blended within the scope of the present invention. Except for this, the amount of magnesia should be set as the balance of the refractory raw material, and it should preferably be contained in an amount of 56% by mass or more.
上記態様の真空脱ガス槽に用いる炭素含有マグネシア質耐火物は、従来公知のマグネシアカーボンれんがと同様に、マグネシア、黒鉛、及びＡｌ−Ｍｇ合金と共に、バインダーとしてフェノール樹脂等を配合しながら、これらの耐火物原料を混錬し、プレス機等を用いて成形して、乾燥させることで得ることができる。なお、本発明の目的から外れない範囲であれば、他の金属粉末や金属化合物粉末等の添加物を耐火物原料として配合してもよい。
また、上記炭素含有マグネシア質耐火物を真空脱ガス槽に内張りする際は、少なくとも溶融スラグと接触する部分にライニングすればよいが、内張り面の全てにライニングしても構わない。The carbon-containing magnesia refractory used in the vacuum degassing tank of the above aspect is blended with magnesia, graphite, and Al-Mg alloy, together with a magnesia carbon brick, and a phenol resin as a binder. It can be obtained by kneading the refractory raw material, forming it using a press machine or the like, and drying it. In addition, as long as it does not deviate from the objective of this invention, you may mix | blend additives, such as another metal powder and metal compound powder, as a refractory raw material.
Further, when the carbon-containing magnesia refractory is lined in a vacuum degassing tank, it may be lined at least at a portion in contact with the molten slag, but may be lined on the entire lined surface.
本発明の上記態様によれば、炭素含有マグネシア質耐火物が元来有する耐熱衝撃性を備えながら、Ｃ／Ｓ質量比が２以下となるような低塩基度スラグが生成する真空脱ガス処理においても、優れた耐用を示す炭素含有マグネシア質耐火物を得ることができる。そして、本発明の上記態様に係る炭素含有マグネシア質耐火物を真空脱ガス槽の内張り耐火物に用いることで、Ａｌ−Ｓｉ−ｋｉｌｌｅｄ鋼、Ｓｉ−ｋｉｌｌｅｄ鋼、Ｓｉ添加鋼等を溶製する際の脱ガス処理を好適に行うことができる。 According to the above aspect of the present invention, in the vacuum degassing process in which a low basicity slag having a C / S mass ratio of 2 or less is generated while having the thermal shock resistance inherent in the carbon-containing magnesia refractory. In addition, a carbon-containing magnesia refractory having excellent durability can be obtained. When the carbon-containing magnesia refractory according to the above-described aspect of the present invention is used as a refractory lining for a vacuum degassing tank, Al-Si-killed steel, Si-killed steel, Si-added steel, etc. are melted. The degassing process can be suitably performed.
本発明の一実施形態に係る真空脱ガス槽及びこれを用いた脱ガス処理方法について、図面を参照しながら以下に説明を行う。
図６に、本実施形態の真空脱ガス槽１を示す。この真空脱ガス槽１は、減圧雰囲気を利用して溶鋼の脱ガス処理を行う炉であり、上部槽２と下部槽３とを同軸に組み合わせて構成されている。上部槽２は、円筒状の鉄皮２１とその内周面を覆う耐火物２２とを備えている。上部槽２の上端は天蓋２３で覆われている。また、上部槽２の側面には、合金投入口２４及び排気口２５が形成されている。
下部槽３は、上部槽２の鉄皮２１と略同径の鉄皮３１と、その内周面を覆う耐火物３２とを備えている。下部槽３の下端には、２本の環流管３３が鉛直方向に沿って設けられている。さらに、これら環流管３３の下端に連なって２本の浸漬管４が取り付けられており、各浸漬管４は、取鍋５内の溶鋼に浸漬されている。A vacuum degassing tank and a degassing method using the same according to an embodiment of the present invention will be described below with reference to the drawings.
In FIG. 6, the vacuum degassing tank 1 of this embodiment is shown. The vacuum degassing tank 1 is a furnace that performs degassing of molten steel using a reduced pressure atmosphere, and is configured by combining an upper tank 2 and a lower tank 3 coaxially. The upper tank 2 includes a cylindrical iron skin 21 and a refractory 22 that covers an inner peripheral surface thereof. The upper end of the upper tank 2 is covered with a canopy 23. Further, an alloy charging port 24 and an exhaust port 25 are formed on the side surface of the upper tank 2.
The lower tank 3 includes an iron skin 31 that is substantially the same diameter as the iron skin 21 of the upper tank 2 and a refractory 32 that covers the inner peripheral surface thereof. Two reflux pipes 33 are provided along the vertical direction at the lower end of the lower tank 3. Further, two dip tubes 4 are attached to the lower ends of the reflux tubes 33, and each dip tube 4 is immersed in the molten steel in the ladle 5.
操業に際しては、この真空脱ガス槽１内の空気を、排気口２５から排出する（図６の矢印Ａ１）ことにより減圧状態にして、取鍋５内の溶鋼を真空脱ガス槽１の内部に吸い上げる。そして、浸漬管４の一方に形成されたガス吹き込み口からＡｒを吹き込んで真空脱ガス槽１内に溶鋼を流入飛散させる（図６の矢印Ｂ１）。このようにして真空脱ガス槽１内で溶鋼の脱ガスが行われ、脱ガスされた溶鋼は他方の浸漬管４から取鍋５内に戻される（図６の矢印Ｂ２）。 In operation, the air in the vacuum degassing tank 1 is exhausted from the exhaust port 25 (arrow A1 in FIG. 6) to reduce the pressure, and the molten steel in the ladle 5 is placed inside the vacuum degassing tank 1. Suck up. And Ar is blown in from the gas blow-in port formed in one side of the dip tube 4, and molten steel flows in and scatters in the vacuum degassing tank 1 (arrow B1 in FIG. 6). In this way, the molten steel is degassed in the vacuum degassing tank 1, and the degassed molten steel is returned from the other dip tube 4 into the ladle 5 (arrow B2 in FIG. 6).
［回転侵食試験］
骨材となる粒径１〜５ｍｍかつ純度９８％以上のマグネシアクリンカーと粒径１ｍｍ未満のマグネシア微粉とからなるＭｇＯ材、粒径１００〜４００ｍｍで純度９７％以上の燐片状黒鉛、粒径４０〜２００ｍｍのＡｌ−Ｍｇ合金粉末（組成Ａｌ１２Ｍｇ１７、純度９９．０%以上）、粒径１０〜１００ｍｍの金属Ａｌ粉末（組成Ａｌ（金属Ａｌ)、純度９９．５%以上）、及びフェノール樹脂を用いて、表１に示した試験Ｎｏ．１〜１２の試験用耐火物原料を用意した。さらに、黒鉛１０質量％、Ａｌ−Ｍｇ合金４質量％、フェノール樹脂２質量％、及びＭｇＯ材８２．３０質量％を用いた試験用耐火物原料（試験Ｎｏ．１６）を用意した。そして、各試験用耐火物原料をオムニミキサーで混錬した後、プレス機を用いて並型れんが（サイズ：６５ｍｍ×１１４ｍｍ×２３０ｍｍ）に成形した。更に、この並型れんがを２００℃で加熱乾燥し、上底４１ｍｍ、下底６７ｍｍ、高さ４８．５ｍｍ、長さ１１４ｍｍに切削して、回転試験用耐火物を得た。[Rotational erosion test]
MgO material composed of magnesia clinker having a particle diameter of 1 to 5 mm and a purity of 98% or more to be an aggregate and magnesia fine powder having a particle diameter of less than 1 mm, flake graphite having a particle diameter of 100 to 400 mm and a purity of 97% or more, particle diameter of 40 Al-Mg alloy powder to 200 mm (composition Al 12 Mg 17, 99.0% purity), metallic Al powder having a particle size of 10 to 100 mm (composition Al (metal Al), 99.5% or more), and phenol Test No. shown in Table 1 using resin. 1 to 12 test refractory raw materials were prepared. Furthermore, a test refractory material (Test No. 16) using 10% by mass of graphite, 4% by mass of an Al—Mg alloy, 2% by mass of a phenol resin, and 82.30% by mass of an MgO material was prepared. And after knead | mixing each refractory raw material for a test with an omni mixer, it shape | molded the average brick (size: 65 mm x 114 mm x 230 mm) using the press machine. Further, this ordinary brick was dried by heating at 200 ° C., and cut into an upper base 41 mm, a lower base 67 mm, a height 48.5 mm, and a length 114 mm to obtain a refractory for a rotation test.
そして、得られた試験用耐火物を、回転ドラム式侵食試験装置（不図示）にそれぞれ内張りして並べ、表２に示すスラグ組成を有した試験用スラグを入れて、１７００℃に加熱しながら８時間回転させて回転侵食試験を行い、内張りした各試験用耐火物の高さ寸法（残寸法）を測定した。なお、試験用スラグは、回転ドラム式侵食試験装置に２０分毎に新しいものを入れ替えるようにした。また、損耗指数は、試験Ｎｏ．４の耐火物の損耗深さを１００とした指数で示しており、数値が小さいほど損耗が少ない。 Then, the obtained test refractories were lined up on a rotating drum type erosion test apparatus (not shown), and the test slag having the slag composition shown in Table 2 was put into the test refractory while heating to 1700 ° C. The rotary erosion test was performed by rotating for 8 hours, and the height dimension (remaining dimension) of each test refractory lined was measured. The test slag was replaced with a new one every 20 minutes in the rotary drum erosion test apparatus. In addition, the wear index is the test number. The wear depth of the refractory No. 4 is indicated by an index of 100, and the smaller the numerical value, the less the wear.
上記のようにして回転侵食試験を行った結果、先ず、図１Ａ及び図１Ｂに示すように、Ａｌ−Ｍｇ合金の添加量がほぼ等しい試験Ｎｏ．１〜３及び５の結果より、黒鉛量が増加するに従い、溶損は抑制されるものの、その含有量が７質量％を超えても溶損の程度にあまり変化がないことが確認された。 As a result of the rotary erosion test as described above, first, as shown in FIGS. From the results of 1 to 3 and 5, it was confirmed that although the erosion loss was suppressed as the amount of graphite increased, there was not much change in the degree of erosion even when the content exceeded 7% by mass.
次に、Ａｌ−Ｍｇ合金粉末の添加量に関し、図２Ａ及び２Ｂに示すように、黒鉛添加量を一定にした試験Ｎｏ．４〜７、１２（Ａｌ−Ｍｇ合金粉末を添加したもの）、及び試験Ｎｏ．８〜１１（金属Ａｌ粉末を添加したもの）の結果から、Ａｌ−Ｍｇ合金粉末の含有量が３．５質量％以上（すなわち、黒鉛との質量比（Ａｌ−Ｍｇ合金／黒鉛）が０．５以上）となることで、金属Ａｌ粉末よりも良好な結果を示し、特にこの質量比が１の場合に最も良好な結果を示した。更には、別の試験によれば、黒鉛の含有量が７質量％の場合に、Ａｌ−Ｍｇ合金粉末の添加量が１４質量％までは、上記と同様に良好な結果を示すことが確認された。 Next, regarding the addition amount of the Al—Mg alloy powder, as shown in FIGS. 4-7, 12 (added with Al-Mg alloy powder), and test no. From the results of 8 to 11 (metal Al powder added), the content of the Al—Mg alloy powder is 3.5 mass% or more (that is, the mass ratio with graphite (Al—Mg alloy / graphite) is 0. 5 or more), a better result than that of the metal Al powder was shown. In particular, when this mass ratio was 1, the best result was shown. Furthermore, according to another test, it was confirmed that when the content of graphite was 7% by mass, the addition of Al-Mg alloy powder showed good results as described above up to 14% by mass. It was.
［耐酸化性評価試験］
試験Ｎｏ．４〜７、９〜１１の試験用耐火物原料を用いて、上記回転侵食試験と同様にして混錬・成型・乾燥した後、φ５０×高さ５０ｍｍの円柱状に切削して、耐酸化性試験用耐火物を得た。得られた試験用耐火物をコークブリーズ中に埋没させた状態で電気炉（不図示）に入れて、昇温速度５℃／分で１０００℃に加熱し、還元雰囲気１０時間の事前焼成を行なった。そして、各試験用耐火物の質量を測定した後、上記電気炉内を大気雰囲気にして、更に１４００℃で４時間の酸化焼成を行なった。[Oxidation resistance evaluation test]
Test No. After kneading, molding and drying in the same manner as in the above rotating erosion test using 4 to 7 and 9 to 11 test refractory raw materials, it was cut into a columnar shape of φ50 × height 50 mm to give oxidation resistance A test refractory was obtained. The obtained test refractory is placed in an electric furnace (not shown) in a state of being buried in a coke breeze, heated to 1000 ° C. at a rate of temperature increase of 5 ° C./min, and pre-baked for 10 hours in a reducing atmosphere. It was. And after measuring the mass of each refractory for a test, the inside of the said electric furnace was made into atmospheric condition, and also oxidation baking for 4 hours was performed at 1400 degreeC.
酸化焼成終了後、各試験用耐火物の質量を測定して、酸化焼成後の質量減少率を求めた。その結果を表１及び図３Ａ及び３Ｂに示す。これらの結果より、金属添加量が３．５質量％以上では、Ａｌ−Ｍｇ合金粉末を添加した試験用耐火物は質量減少量がわずかになり、耐酸化性に優れることが分る。また、酸化焼成終了後の各試験用耐火物を輪切りにして、その横断面を撮影した写真を図４の（ａ）〜（ｇ）に示す。これらの写真からも、Ａｌ−Ｍｇ合金粉末を３．５質量％以上添加した（ｃ），（ｄ）が耐酸化性において優れていることが分る。 After the oxidation firing, the mass of each test refractory was measured to determine the mass reduction rate after the oxidation firing. The results are shown in Table 1 and FIGS. 3A and 3B. From these results, it can be seen that when the metal addition amount is 3.5% by mass or more, the test refractory to which the Al—Mg alloy powder is added has a small decrease in mass and is excellent in oxidation resistance. Moreover, the photograph which cut | disconnected each test refractory after completion | finish of oxidation baking, and image | photographed the cross section is shown to (a)-(g) of FIG. Also from these photographs, it can be seen that (c) and (d), in which 3.5% by mass or more of Al—Mg alloy powder is added, are excellent in oxidation resistance.
［真空溶解炉による侵食試験］
上記回転侵食試験で用意したものと同様の試験Ｎｏ．４〜７及び１２の試験用耐火物原料と；黒鉛７質量％、Ａｌ−Ｍｇ合金１４質量％、フェノール樹脂２質量％、及び残部をＭｇＯ材として準備した試験用耐火物原料（試験Ｎｏ．１３）と；黒鉛９質量％、Ａｌ−Ｍｇ合金９質量％、フェノール樹脂２質量％、及び残部をＭｇＯ材として準備した試験用耐火物原料（試験Ｎｏ．１４）と；黒鉛８質量％、Ａｌ−Ｍｇ合金８質量％、フェノール樹脂２質量％、及びＭｇＯ材８０．３６質量％として準備した試験用耐火物原料（試験Ｎｏ．１５）と；を用意し、回転侵食試験と同様にして混錬・成型・乾燥した。そしてこの後、上底４６ｍｍ、下底７０ｍｍ、高さ３０ｍｍ、長さ２３０ｍｍのサイズに切削して、真空溶解炉侵食試験用サンプルを得た。得られた試験用耐火物を、５０ｋｇ真空溶解炉（不図示）内にそれぞれ内張りして並べ、前述の表２に示すスラグ組成を有した試験用スラグを入れて、１６５０℃に加熱しながら、脱ガス処理を模擬して、１．３ｋＰａ（１０Ｔｏｒｒ）まで減圧し、３時間保持した後、内張りした各試験用耐火物の高さ寸法（残寸法）を測定して、損耗深さを求めた。[Erosion test by vacuum melting furnace]
Test No. similar to that prepared in the above rotating erosion test. Test refractory raw materials 4 to 7 and 12; Graphite 7 mass%, Al-Mg alloy 14 mass%, phenol resin 2 mass%, and the remainder prepared as MgO material (test No. 13) ); 9% by mass of graphite, 9% by mass of an Al—Mg alloy, 2% by mass of phenol resin, and a refractory raw material for test (test No. 14) prepared as the MgO material; and 8% by mass of graphite, Al— Refractory raw material for test (test No. 15) prepared as Mg alloy 8% by mass, phenol resin 2% by mass, and MgO material 80.36% by mass. Molded and dried. Thereafter, the sample was cut into a size of 46 mm at the upper base, 70 mm at the lower base, 30 mm in height, and 230 mm in length to obtain a sample for a vacuum melting furnace erosion test. The obtained test refractories were lined up and lined in a 50 kg vacuum melting furnace (not shown), and the test slag having the slag composition shown in Table 2 above was placed and heated to 1650 ° C., Simulating the degassing process, reducing the pressure to 1.3 kPa (10 Torr) and holding it for 3 hours, then measuring the height dimension (remaining dimension) of each test refractory lined to determine the wear depth. .
上記のような低塩基度スラグ、減圧下においても、黒鉛添加量を一定にした試験Ｎｏ．４〜７、１２及び１３の結果から、表１に示したように、Ａｌ−Ｍｇ合金粉末の含有量が３．５質量％以上で損耗深さが低減され、良好な結果を示すことが判る。これらの結果をグラフにした図５から分るように、黒鉛に対するＡｌ−Ｍｇ合金の質量比（Ａｌ−Ｍｇ合金／黒鉛）が０．５以上となることで、損耗量（損耗深さ)が低減し、更に、この質量比が１〜２の場合により良好な結果を示すことが確認された。 Test No. 1 with the same amount of graphite added even under the low basicity slag and reduced pressure as described above. From the results of 4 to 7, 12 and 13, as shown in Table 1, it is understood that the wear depth is reduced when the content of the Al—Mg alloy powder is 3.5% by mass or more, and good results are shown. . As can be seen from FIG. 5 which graphs these results, the amount of wear (depth of wear) is increased when the mass ratio of Al—Mg alloy to graphite (Al—Mg alloy / graphite) is 0.5 or more. Further, it was confirmed that better results were obtained when the mass ratio was 1-2.
以上の試験結果を受け、本実施形態の骨子を以下に述べる。
図６に示した本実施形態の真空脱ガス槽１は、鉄皮２１，３１と、これら鉄皮２１，３１の内部を覆う耐火物２２，３２とを備え、減圧雰囲気で溶鋼の脱ガス処理を行う。そして、耐火物２２，３２のうちの全て又は少なくとも溶融スラグとの接触部分に、炭素含有マグネシア質耐火物がライニングされている。しかも、前記炭素含有マグネシア質耐火物は、７質量％以上かつ２８％未満の黒鉛と、３．５質量％以上かつ１４質量％以下のＡｌ−Ｍｇ合金とを有し、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５以上２．０以下でありかつ、残部がマグネシア及び不可避的不純物からなる。なお、前記質量比の下限値を１．０とすることがより好ましい。
また、本発明における不可避的不純物には、製造工程で少量添加されるフェノール樹脂等のバインダーも含まれる。バインダーは乾燥工程で一部揮発するが残部が耐火物中に残る。本発明においては、原料中に含まれる不可避的不純物だけでなく、このバインダーの残部も不可避的不純物として定義する。
なお、前記マグネシアの含有量は、５８質量％以上かつ８９．５質量％未満とすることができる。その理由は、前記黒鉛が２８質量％を超えない上限値であり、前記Ａｌ−Ｍｇ合金が１４質量％であった場合、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５をわずかに超える値であり、残部となる前記マグネシアが５８質量％以上となり、また、前記黒鉛が７質量％で前記Ａｌ−Ｍｇ合金が３．５質量％であった時は前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５であり、これより残部の前記マグネシアは８９．５質量％未満となるためである。Based on the above test results, the outline of this embodiment will be described below.
The vacuum degassing tank 1 of the present embodiment shown in FIG. 6 includes iron skins 21 and 31 and refractories 22 and 32 that cover the insides of the iron skins 21 and 31, and degassed molten steel in a reduced-pressure atmosphere. I do. A carbon-containing magnesia refractory is lined at all or at least a contact portion with the molten slag among the refractories 22 and 32. In addition, the carbon-containing magnesia refractory has 7% by mass or more and less than 28% graphite and 3.5% by mass or more and 14% by mass or less of an Al—Mg alloy, The mass ratio obtained by dividing the mass by the mass of the graphite is 0.5 or more and 2.0 or less, and the balance is composed of magnesia and inevitable impurities. The lower limit of the mass ratio is more preferably 1.0.
In addition, the inevitable impurities in the present invention include binders such as phenol resins that are added in a small amount in the production process. The binder partially volatilizes during the drying process, but the remainder remains in the refractory. In the present invention, not only inevitable impurities contained in the raw material but also the remainder of the binder is defined as inevitable impurities.
In addition, content of the said magnesia can be 58 mass% or more and less than 89.5 mass%. The reason is that the upper limit of the graphite does not exceed 28% by mass, and when the Al—Mg alloy is 14% by mass, the mass ratio obtained by dividing the mass of the Al—Mg alloy by the mass of the graphite is The value is slightly over 0.5, the remaining magnesia is 58% by mass or more, and when the graphite is 7% by mass and the Al—Mg alloy is 3.5% by mass, the Al This is because the mass ratio obtained by dividing the mass of the Mg alloy by the mass of the graphite is 0.5, and the remaining magnesia is less than 89.5 mass%.
本実施形態の真空脱ガス処理方法は、上記構成を有する真空脱ガス槽１を用いて、ＣａＯ／ＳｉＯ２≦２の低塩基度スラグが生成するような真空脱ガス処理を行う。なお、真空脱ガス槽１中にＳｉ又はＳｉ合金を添加して鋼の二次精錬を行いながら、前記真空脱ガス処理を行ってもよい。The vacuum degassing method of the present embodiment performs a vacuum degassing process using the vacuum degassing tank 1 having the above-described configuration so that a low basicity slag of CaO / SiO 2 ≦ 2 is generated. In addition, you may perform the said vacuum degassing process, adding Si or Si alloy in the vacuum degassing tank 1, and performing the secondary refining of steel.
以上説明のように、本実施形態の炭素含有マグネシア質耐火物は、Ａｌ−Ｍｇ合金粉末を３．５〜１４質量％含有し、かつ、黒鉛との質量比を０．５以上とすることで、低塩基度スラグに対して優れた耐用を示し、また、脱ガス処理のような減圧下においても非常に優れた耐用を示すことが確認された。これは、従来の炭素含有マグネシア質耐火物の欠点を克服し、製鉄業の脱ガス処理の操業条件下で耐火物寿命向上に大きく貢献する。 As explained above, the carbon-containing magnesia refractory of the present embodiment contains 3.5 to 14% by mass of Al—Mg alloy powder and the mass ratio with graphite is 0.5 or more. It has been confirmed that it exhibits excellent durability against low basicity slag and also exhibits extremely excellent durability even under reduced pressure such as degassing treatment. This overcomes the drawbacks of conventional carbon-containing magnesia refractories and greatly contributes to the improvement of the refractory life under the operating conditions of the degassing treatment of the steel industry.
１ 真空脱ガス槽
２１，３１ 鉄皮
２２，３２ 耐火物
1 Vacuum degassing tank 21, 31 Iron skin 22, 32 Refractory
Claims (4)
前記耐火物のうちの少なくとも溶融スラグとの接触部分に、炭素含有マグネシア質耐火物が設けられ；
前記炭素含有マグネシア質耐火物は、７質量％以上かつ２８％未満の黒鉛と、７質量％以上かつ１４質量％以下のＡｌ−Ｍｇ合金とを有してかつ、残部がマグネシア及び不可避的不純物からなり、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５以上２．０以下である；
ことを特徴とする真空脱ガス槽。A vacuum degassing tank comprising an iron skin and a refractory material covering the inside of the iron skin, and used for degassing a molten steel in which a low basicity slag of CaO / SiO 2 ≦ 2 is generated in a reduced pressure atmosphere. ,
A carbon-containing magnesia refractory is provided at least in contact with the molten slag among the refractories;
The carbon-containing magnesia refractory comprises 7% by mass or more and less than 28% graphite, and 7 % by mass or more and 14% by mass or less of an Al—Mg alloy, with the balance being magnesia and inevitable impurities. And the mass ratio obtained by dividing the mass of the Al—Mg alloy by the mass of the graphite is 0.5 or more and 2.0 or less;
A vacuum degassing tank characterized by that.
前記真空脱ガス槽は、前記耐火物のうちの少なくとも溶融スラグとの接触部分に、炭素含有マグネシア質耐火物が設けられ；
前記炭素含有マグネシア質耐火物は、７質量％以上かつ２８％未満の黒鉛と、３．５質量％以上かつ１４質量％以下のＡｌ−Ｍｇ合金とを有してかつ、残部がマグネシア及び不可避的不純物からなり、前記Ａｌ−Ｍｇ合金の質量を前記黒鉛の質量で除算した質量比が０．５以上２．０以下である；
ことを特徴とする真空脱ガス処理方法。 Using a vacuum degassing tank equipped with an iron skin and a refractory covering the inside of the iron skin , degassing treatment of molten steel such that low basicity slag of CaO / SiO 2 ≦ 2 is generated in a reduced pressure atmosphere. A vacuum degassing method to be performed,
The vacuum degassing tank is provided with a carbon-containing magnesia refractory at least in contact with the molten slag among the refractories;
The carbon-containing magnesia refractory has 7% by mass or more and less than 28% graphite and 3.5% by mass or more and 14% by mass or less of an Al—Mg alloy with the balance being magnesia and inevitable. A mass ratio consisting of impurities, wherein the mass ratio of the Al-Mg alloy divided by the mass of the graphite is 0.5 or more and 2.0 or less;
A vacuum degassing method characterized by the above.
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|---|---|---|---|
| PCT/JP2011/060278 WO2012147180A1 (en) | 2011-04-27 | 2011-04-27 | Vacuum degassing tank and method for degassing using same |
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| JP5068887B1 true JP5068887B1 (en) | 2012-11-07 |
| JPWO2012147180A1 JPWO2012147180A1 (en) | 2014-07-28 |
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| JP (1) | JP5068887B1 (en) |
| KR (1) | KR101403131B1 (en) |
| CN (1) | CN103492344B (en) |
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| JP7389352B2 (en) | 2020-03-26 | 2023-11-30 | 日本製鉄株式会社 | Spinel-magnesia-carbon bricks for vacuum degassing equipment and vacuum degassing equipment |
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- 2011-04-27 CN CN201180070369.4A patent/CN103492344B/en not_active Expired - Fee Related
- 2011-04-27 JP JP2011544715A patent/JP5068887B1/en not_active Expired - Fee Related
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Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2012147180A1 (en) | 2014-07-28 |
| BR112013027385B1 (en) | 2020-03-03 |
| KR101403131B1 (en) | 2014-06-03 |
| CN103492344B (en) | 2016-06-29 |
| KR20130126748A (en) | 2013-11-20 |
| WO2012147180A1 (en) | 2012-11-01 |
| BR112013027385A2 (en) | 2017-01-17 |
| CN103492344A (en) | 2014-01-01 |
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