JP3081067B2 - Liquid steel surface heat insulator - Google Patents
Liquid steel surface heat insulatorInfo
- Publication number
- JP3081067B2 JP3081067B2 JP04197477A JP19747792A JP3081067B2 JP 3081067 B2 JP3081067 B2 JP 3081067B2 JP 04197477 A JP04197477 A JP 04197477A JP 19747792 A JP19747792 A JP 19747792A JP 3081067 B2 JP3081067 B2 JP 3081067B2
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- JP
- Japan
- Prior art keywords
- molten steel
- sio
- content
- heat insulating
- heat insulator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Description
【０００１】[0001]
【産業上の利用分野】本発明は連続鋳造用タンディッシ
ュや取鍋などにより溶鋼を移送、又は精錬処理を行なう
際に、断熱・保温あるいは空気酸化防止を目的として溶
鋼表面を被覆する溶鋼表面保温剤に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the insulation of a molten steel surface to cover the surface of the molten steel for the purpose of heat insulation, heat insulation or prevention of air oxidation when the molten steel is transferred or smelted by a continuous casting tundish or a ladle. It relates to the agent.
【０００２】[0002]
【従来の技術】連続鋳造用タンディッシュや取鍋などに
より溶鋼を移送、又は精錬処理を行なう際、保温剤を用
いて溶鍋表面を被覆し溶鋼からの熱放散と外気の侵入を
防止している。従来から保温剤としては、籾殻を蒸し焼
きにした焼籾が主に用いられ、その主成分はＳｉＯ2と
Ｃである。ＳｉＯ2は熱伝導率が低く保温効果に、Ｃは
酸素をＣＯガスに変えるため酸素の遮断効果に優れてい
る。このため、焼籾は保温効果及び空気遮断効果を有
し、しかも安価であることを特徴とする保温剤である。2. Description of the Related Art When transferring molten steel using a tundish or ladle for continuous casting or performing refining, the surface of the molten steel is coated with a heat insulating agent to prevent heat dissipation from the molten steel and intrusion of outside air. I have. Conventionally, as a heat retaining agent, roasted rice obtained by steaming rice husks is mainly used, and its main components are SiO 2 and C. SiO 2 has a low thermal conductivity and has a heat retaining effect, and C has an excellent oxygen blocking effect because it converts oxygen into CO gas. For this reason, baked rice is a heat insulator characterized by having a heat insulating effect and an air blocking effect, and being inexpensive.
【０００３】しかしながら、加工性向上の目的から鋼板
中のＣ濃度を極力低下させた、例えばＣ濃度が５０ｐｐ
ｍ以下の極低炭素鋼において、保温剤中のＣ成分が溶鋼
中にピックアップし鋼材の特性を低下させる欠点が知ら
れている。また、保温剤中のＳｉＯ2 成分は溶鋼中のＡ
ｌと反応しＡｌ2Ｏ3系の介在物を生成するため、表面欠
陥を増大させるといった問題も生じる。However, in order to improve the workability, the C concentration in the steel sheet is reduced as much as possible.
It has been known that, in ultra-low carbon steels of m or less, the C component in the heat insulating agent is picked up in the molten steel and deteriorates the properties of the steel material. In addition, the SiO 2 component in the heat insulator is A in the molten steel.
Since it reacts with 1 to generate Al 2 O 3 -based inclusions, a problem of increasing surface defects also arises.
【０００４】従来、焼籾のこれら欠点を解決するため、
Ｃ及びＳｉＯ2 成分の少ない保温剤として、例えば特公
平３−４８１５２号公報に記載されているように、Ｍｇ
Ｏ系の保温剤が使用されている。また、ＭｇＯ自体は熱
伝導率が高いため、これに断熱性を付与した発泡ＭｇＯ
の製造方法についても種々検討され、特公昭４８−７４
８５号公報等に記載されている。[0004] Conventionally, in order to solve these drawbacks of baked rice,
As little heat retaining agent of C and SiO 2 components, as described in JP Kokoku 3-48152, Mg
An O-based warming agent is used. In addition, since MgO itself has a high thermal conductivity, foamed MgO having heat insulating property is added thereto.
Various studies have also been made on the production method of
No. 85, etc.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、ＭｇＯ
を主成分とする保温剤は融点が高く、使用温度では主に
固相であるため、溶鋼表面の均一な被覆状態が得られ
ず、外気と溶鋼との反応によりＡｌ2Ｏ3系介在物を生成
する。また、タンディッシュではモールド内への溶鋼供
給を制御するためにストッパーを使用しているが、Ｍｇ
Ｏ系保温剤は粒子間で焼結が進み強固なスラグ層を形成
するためストッパー制御が困難となり、激しい場合には
ストッパーの折損に到る。SUMMARY OF THE INVENTION However, MgO
The main component of the heat insulator has a high melting point and is mainly in a solid phase at the operating temperature, so that a uniform coating state on the surface of the molten steel cannot be obtained, and the reaction between the outside air and the molten steel causes Al 2 O 3 inclusions to be formed. Generate. In addition, the tundish uses a stopper to control the supply of molten steel into the mold.
The sintering progresses between the particles of the O-based heat insulator to form a strong slag layer, so that it is difficult to control the stopper. If the slag is severe, the stopper may be broken.
【０００６】これに対し、ＭｇＯの一部をＳｉＯ2 に置
き換え融点を下げる方法が考えられるが、この場合溶鋼
中ＡｌによりＳｉＯ2の還元が起こる。これらの問題を
鑑み、本発明は、空気酸化と保温剤の反応に起因する溶
鋼汚染を確実に防止し、その上で耐火物の損傷や溶損が
ない保温剤を提供することを目的とするものである。On the other hand, a method of lowering the melting point by replacing a part of MgO with SiO 2 is considered. In this case, Al in the molten steel causes reduction of SiO 2 . In view of these problems, an object of the present invention is to surely prevent molten steel contamination due to the reaction between air oxidation and a heat insulator, and to provide a heat insulator that is free from damage or melting damage of refractories. Things.
【０００７】[0007]
【課題を解決するための手段】本発明は、ＣａＯとＡｌ
2Ｏ3の含有率をＣａＯ／Ａｌ2Ｏ3で０．５〜２．０と
し、且つＭｇＯ含有率を３０〜６０％、ＳｉＯ2 含有率
を１０％以下にしたことを特徴とする溶鋼表面保温剤に
関するものである。The present invention is directed to CaO and Al.
The content of 2 O 3 and 0.5 to 2.0 at CaO / Al 2 O 3, and the MgO content of 30% to 60%, the molten steel surface, characterized in that the SiO 2 content of 10% or less It relates to a heat insulator.
【０００８】[0008]
【作用】溶鋼表面を被覆する保温剤として満足すべき条
件は、空気酸化と保温剤の反応に起因する溶鋼汚染を確
実に防止し、その上で耐火物の損傷や溶損がないことで
ある。本発明者等はこれら基本条件を満足すべく保温剤
の検討を進めてきた結果、空気酸化を抑制するためには
保温剤の液相化が、保温剤と溶鋼の反応を防止するため
には低ＳｉＯ2化が有効であることを見いだした。The desired condition for the heat insulator to coat the molten steel surface is to reliably prevent the molten steel from being contaminated due to the reaction between the air oxidation and the heat insulator, and to prevent damage or melting of the refractory. . The present inventors have been studying a heat insulating agent to satisfy these basic conditions.As a result, in order to suppress air oxidation, the liquid phase of the heat insulating agent is used to prevent the reaction between the heat insulating agent and molten steel. It has been found that reduction of SiO 2 is effective.
【０００９】すなわち、保温剤の融点を下げ液相を生成
することは溶鋼表面の被覆状態を均一化し、保温剤自体
の空気酸化防止能を高める。また、保温剤中のＳｉＯ2
は（１）式により溶鋼中のＡｌと反応するため、保温剤
の低ＳｉＯ2 化はＡｌ2Ｏ3系介在物の生成防止に効果を
有する。 ３ＳｉＯ2＋４Ａｌ＝２Ａｌ2Ｏ3＋３Ｓｉ （１）That is, lowering the melting point of the heat insulating agent to form a liquid phase makes the coating state on the surface of the molten steel uniform, and enhances the ability of the heat insulating agent itself to prevent air oxidation. In addition, SiO 2 in the heat insulator
Reacts with Al in the molten steel according to the formula (1), so that the use of a low heat insulating agent in SiO 2 is effective in preventing the formation of Al 2 O 3 inclusions. 3SiO 2 +4 Al = 2Al 2 O 3 +3 Si (1)
【００１０】以上の点を考慮して液相化と低ＳｉＯ2 化
を満足し、さらに介在物吸収を具備する保温剤について
検討を重ねた結果、ＣａＯとＡｌ2Ｏ3の含有率をＣａＯ
／Ａｌ2Ｏ3で０．５〜２．０の範囲とし、ＳｉＯ2 含有
率を１０％以下にすることが最適であることを明らかに
した。[0010] In consideration of the above points, the liquid phase and low SiO 2 were satisfied, and further studies were conducted on a heat retaining agent having an inclusion absorption. As a result, the content of CaO and Al 2 O 3 was reduced to CaO.
/ Al 2 O 3 in the range of 0.5 to 2.0, and the SiO 2 content of 10% or less was found to be optimal.
【００１１】ここに、ＣａＯ／Ａｌ2Ｏ3を０．５〜２．
０の範囲にしたのは、図１に示すように保温剤の融点が
タンディッシュにおける溶鋼温度（１５５０℃）以下と
なり、液相化するためである。また、ＳｉＯ2 含有率を
１０％以下にしたのは、図２に示すようにＳｉＯ2 の活
量が極めて小さくなり、工業的に問題となる様な保温剤
と溶鋼の反応を防止できるためである。しかし、本成分
の保温剤をタンディッシュに適用した場合、ストッパー
耐火物の溶損が急激に進行し、長時間の使用に耐えない
ことが分かった。Here, CaO / Al 2 O 3 is added in an amount of 0.5-2.
The reason for setting the range to 0 is that, as shown in FIG. 1, the melting point of the heat insulating agent becomes lower than the molten steel temperature (1550 ° C.) in the tundish, and the liquid phase becomes liquid. The reason why the content of SiO 2 is set to 10% or less is that the activity of SiO 2 becomes extremely small as shown in FIG. 2 and the reaction between the heat retaining agent and the molten steel, which may be an industrial problem, can be prevented. is there. However, it was found that when the heat retaining agent of this component was applied to the tundish, the erosion of the stopper refractory progressed rapidly, and it could not withstand long-term use.
【００１２】そこで、本発明者らは、前述した成分の保
温剤にＭｇＯを添加し、保温剤が固相化しない範囲で融
点を上げ、ストッパー耐火物の溶損防止を検討した。そ
の結果を図３に示す。図から明らかなように、ストッパ
ー耐火物の溶損はＭｇＯを３０％以上添加することによ
り工業的に使用可能なまでに抑制できる。Therefore, the present inventors added MgO to the above-mentioned heat insulating agent, raised the melting point within a range in which the heat insulating agent did not solidify, and studied the prevention of erosion of the refractory stopper. The result is shown in FIG. As is apparent from the figure, the erosion of the stopper refractory can be suppressed to an industrially usable level by adding 30% or more of MgO.
【００１３】しかし、図４に示すように溶鋼温度（１５
５０℃）でＭｇＯ含有率が６０％を超えると、保温剤中
の液相は極めて少なくなる。その結果、保温剤は溶鋼表
面を均一に覆わず、外気の侵入によりＡｌ2Ｏ3系の介在
物を生成する。したがって、保温剤への最適なＭｇＯ含
有率は３０〜６０％である。また、耐火物の溶損機構に
ついても詳細な調査を実施し、耐火物気孔内への保温剤
の浸透が溶損速度を律すること、さらにＭｇＯ含有率が
３０％以上では保温剤の融点が増大し固・液共存相にな
るため液相の見掛けの粘性が高まり、耐火物気孔内への
浸透が抑制されることを見出した。However, as shown in FIG.
If the MgO content exceeds 50% at (50 ° C.), the liquid phase in the heat insulating agent becomes extremely small. As a result, the heat insulating agent does not uniformly cover the surface of the molten steel, and generates Al 2 O 3 -based inclusions by the invasion of the outside air. Therefore, the optimal MgO content in the heat insulator is 30 to 60%. In addition, we conducted detailed investigations on the erosion mechanism of refractories, and found that the penetration of the heat insulator into the pores of the refractory determines the erosion rate, and the melting point of the heat insulator increases when the MgO content is 30% or more. Since the solid-liquid coexisting phase is formed, the apparent viscosity of the liquid phase is increased, and the permeation into the refractory pores is suppressed.
【００１４】保温剤の基本的成分は以上に述べた通りで
あるが、本発明品の機能を低下させない範囲で、ＣａＣ
ｌ2、ＣａＦ2等の他成分の添加も可能である。以上に示
したように、本発明の保温剤を用いることにより空気酸
化と保温剤の反応に起因する溶鋼汚染を確実に防止で
き、その上で耐火物の損傷や溶損がない溶鋼保温剤を提
供できる。The basic components of the heat insulating agent are as described above. However, as long as the function of the product of the present invention is not reduced, CaC
It is also possible to add other components such as l 2 and CaF 2 . As described above, by using the heat insulating agent of the present invention, molten steel contamination caused by the reaction between air oxidation and the heat insulating agent can be reliably prevented, and furthermore, a molten steel heat insulating agent having no refractory damage or melting damage can be obtained. Can be provided.
【００１５】[0015]
【実施例】以下に、実施例及び比較例を挙げて、本発明
について説明する。表１に示す成分の保温剤４００ｋｇ
を容量６０ｔｏｎのダンディッシュに添加し、低炭アル
ミキルド鋼を４００分間鋳造した。本発明の実施例及び
比較例とも、鋳造寸法は厚み２４５ｍｍ×幅１５００ｍ
ｍで、８５００ｍｍ長さに切断して１コイル単位とし
た。このスラブを常法により熱間圧延、冷間圧延し、最
終的に厚み０．７ｍｍ×幅１５００ｍｍコイルの冷延鋼
板とした。保温剤の空気遮断効果及び反応防止効果はタ
ンディッシュ入側と出側の全酸素量の上昇量及び冷延鋼
板に発生した表面欠陥の発生個数により評価した。ま
た、耐火物の溶損については使用後ストッパーの溶損量
を測定し、鋳造時間から溶損速度を算出した。なお、鋳
造において使用したストッパー耐火物の材質はロウセキ
であった。The present invention will be described below with reference to examples and comparative examples. Insulation agent of the components shown in Table 1 400 kg
Was added to a 60-ton dundish, and a low-carbon aluminum killed steel was cast for 400 minutes. In both the examples and the comparative examples of the present invention, the casting size is 245 mm thick × 1500 m wide.
m, it was cut into 8500 mm lengths to make one coil unit. The slab was hot-rolled and cold-rolled by a conventional method to finally form a cold-rolled steel sheet having a coil having a thickness of 0.7 mm and a width of 1500 mm. The air-blocking effect and the reaction-preventing effect of the heat insulator were evaluated based on the amount of increase in the total oxygen content on the inlet and outlet sides of the tundish and the number of surface defects generated on the cold-rolled steel sheet. For the erosion of the refractory, the amount of erosion of the stopper after use was measured, and the erosion rate was calculated from the casting time. The material of the stopper refractory used in the casting was wax wax.
【００１６】 [0016]
【００１７】表２に示す如く、実施例ではＣａＯとＡｌ
2Ｏ3の含有率をＣａＯ／Ａｌ2Ｏ3で０．５〜２．０と
し、且つＭｇＯ含有率を３０〜６０％、ＳｉＯ2 含有率
を１０％以下にしたことで、空気酸化と保温剤の反応に
起因する溶鋼汚染を防止できたため、タンディッシュ内
での全酸素量の上昇及び表面欠陥の発生は全くなかっ
た。また、ストッパー耐火物の溶損速度も低下するた
め、連々鋳回数が増加する場合にも十分使用に耐えうる
ことが確認された。As shown in Table 2, in Examples, CaO and Al
The content of 2 O 3 and 0.5 to 2.0 at CaO / Al 2 O 3, and the MgO content of 30% to 60%, by making the SiO 2 content of 10% or less, insulation and air oxidation Since the molten steel contamination due to the reaction of the chemicals was prevented, there was no increase in the total oxygen amount in the tundish and no generation of surface defects. In addition, it was confirmed that the rate of erosion of the stopper refractory also decreased, so that even if the number of times of casting increased continuously, it could be sufficiently used.
【００１８】これに対し、比較例１はＭｇＯ含有率が低
かったため、ストッパー耐火物の溶損を抑えることがで
きず、保温剤投入後３５０分で鋳造を停止した。比較例
２はＭｇＯ含有率が６０％を超えたため、比較例３と比
較例４はＣａＯ／Ａｌ2Ｏ3が０．５〜２．０の範囲外で
あったため、保温剤が固相となり十分な断気効果が得ら
れず、タンディッシュ内溶鋼の全酸素量が上昇し表面欠
陥が発生した。また、比較例５はＳｉＯ2 含有率が１０
％を超えたため、溶鋼中Ａｌとの反応によりＡｌ2Ｏ3系
介在物が生成した。その結果、タンディッシュ内溶鋼の
全酸素量が増大し、表面欠陥が発生した。On the other hand, in Comparative Example 1, since the MgO content was low, it was not possible to suppress the erosion of the stopper refractory, and the casting was stopped 350 minutes after the addition of the heat retaining agent. In Comparative Example 2, the MgO content exceeded 60%, and in Comparative Examples 3 and 4, CaO / Al 2 O 3 was out of the range of 0.5 to 2.0. As a result, the total oxygen content of the molten steel in the tundish increased, causing surface defects. In Comparative Example 5, the SiO 2 content was 10%.
%, The reaction with Al in the molten steel produced Al 2 O 3 -based inclusions. As a result, the total oxygen content of the molten steel in the tundish increased, and surface defects occurred.
【００１９】[0019]
【表２】 [Table 2]
【００２０】[0020]
【発明の効果】以上に説明したように、本発明の溶鋼保
温剤によれば溶鋼の汚染は全くなく、鋳片品質は極めて
向上する。また、耐火物の損傷や溶損も生じないため、
操業面でも有効な保温剤を提供できる。As described above, according to the heat retaining agent for molten steel of the present invention, there is no contamination of the molten steel, and the quality of the slab is extremely improved. Also, no refractory damage or erosion occurs,
An effective heat insulating agent can be provided also in operation.
【図１】保温剤のＣａＯ／Ａｌ2Ｏ3と融点の関係を示す
図、FIG. 1 is a diagram showing a relationship between CaO / Al 2 O 3 of a heat insulating agent and a melting point,
【図２】保温剤中のＳｉＯ2含有率とＳｉＯ2の活量の関
係を示す図、FIG. 2 is a graph showing the relationship between the content of SiO 2 in a heat insulator and the activity of SiO 2 ;
【図３】保温剤中のＭｇＯ添加量と溶損速度の関係を示
す図、FIG. 3 is a diagram showing the relationship between the amount of MgO added in a heat insulator and the rate of melting,
【図４】保温剤の液相率とＭｇＯ含有率の関係を示す図
である。FIG. 4 is a diagram showing the relationship between the liquid phase ratio of the heat insulating agent and the MgO content.
Claims (1)
ｌ2Ｏ3で０．５〜２．０とし、且つＭｇＯ含有率を３０
〜６０％、ＳｉＯ2 含有率を１０％以下にしたことを特
徴とする溶鋼表面保温剤。1. The content of CaO and Al 2 O 3 is adjusted to CaO / A
l 2 O 3 to 0.5 to 2.0 and a MgO content of 30
A molten steel surface heat insulating agent characterized in that the content of SiO 2 is set to not more than 60% and the content of SiO 2 is not more than 10%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP04197477A JP3081067B2 (en) | 1992-07-02 | 1992-07-02 | Liquid steel surface heat insulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP04197477A JP3081067B2 (en) | 1992-07-02 | 1992-07-02 | Liquid steel surface heat insulator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0624832A JPH0624832A (en) | 1994-02-01 |
| JP3081067B2 true JP3081067B2 (en) | 2000-08-28 |
Family
ID=16375137
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP04197477A Expired - Fee Related JP3081067B2 (en) | 1992-07-02 | 1992-07-02 | Liquid steel surface heat insulator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3081067B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3719561C2 (en) * | 1986-06-12 | 1998-12-10 | Morita Mfg | Medical light irradiation handpiece |
| KR100436506B1 (en) * | 1997-04-30 | 2004-08-18 | 주식회사 포스코 | Ladle heat-insulating material for ultra-low carbon special molten steel, excellent in heat keeping ability, alumina absorptivity, and corrosion-resistance to magnesia refractory |
| KR20020052131A (en) * | 2000-12-23 | 2002-07-02 | 이구택 | Insulator for molten iron using by-products in ironmaking processes |
| WO2005115660A1 (en) * | 2004-05-19 | 2005-12-08 | Metakon Gmbh | Method for treating a metal melt |
-
1992
- 1992-07-02 JP JP04197477A patent/JP3081067B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0624832A (en) | 1994-02-01 |
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