JP2929912B2 - Stirring method of molten metal - Google Patents
Stirring method of molten metalInfo
- Publication number
- JP2929912B2 JP2929912B2 JP25820593A JP25820593A JP2929912B2 JP 2929912 B2 JP2929912 B2 JP 2929912B2 JP 25820593 A JP25820593 A JP 25820593A JP 25820593 A JP25820593 A JP 25820593A JP 2929912 B2 JP2929912 B2 JP 2929912B2
- Authority
- JP
- Japan
- Prior art keywords
- molten metal
- stirring
- ladle
- tuyere
- gas
- 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.)
- Expired - Lifetime
Links
Landscapes
- Manufacture And Refinement Of Metals (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、溶融金属の取鍋精錬を
行う際の溶融金属の攪拌方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for agitating molten metal during ladle refining of molten metal.
【０００２】[0002]
【従来の技術】溶融金属として溶鋼を例に挙げて説明す
ると、従来より、溶鋼の取鍋精錬において浸漬管を用い
た減圧精錬装置の攪拌方法としては、すでに各種の方式
のものが提案されている。2. Description of the Related Art A molten steel is taken as an example of a molten metal. Conventionally, as a stirring method of a vacuum refining apparatus using an immersion pipe in ladle refining of molten steel, various methods have been proposed. I have.
【０００３】例えば、特開昭63−140029号公報に開示さ
れる方法によれば、浸漬管外周部に電磁気発生装置を設
置し、これによって溶鋼を攪拌するのである。しかし、
このような電磁気による攪拌を行う場合、多大な電力を
消費しなければならず、設備上も膨大な費用が必要とな
り、管理、維持に手間がかかるなどの問題がある。[0003] For example, according to the method disclosed in Japanese Patent Application Laid-Open No. 63-140029, an electromagnetic generator is installed on the outer periphery of a dip tube, and thereby the molten steel is stirred. But,
When such electromagnetic stirring is performed, a large amount of electric power must be consumed, enormous costs are required for the equipment, and there is a problem that management and maintenance are troublesome.
【０００４】一方、特開平４−59912 号公報にはガス吹
込みによる攪拌方法が開示されおり、これによれば、浸
漬管断面を楕円形とし、取鍋底部に設置するポーラスプ
ラグの位置を浸漬管中心より楕円長軸方向に偏心させて
設置している。しかし、偏心の程度により以下の問題が
生じる。On the other hand, Japanese Unexamined Patent Publication No. Hei 4-59912 discloses a stirring method by gas injection. According to this method, the cross section of an immersion tube is made elliptical, and the position of a porous plug installed at the bottom of a ladle is immersed. It is installed eccentrically in the elliptical long axis direction from the center of the tube. However, the following problems occur depending on the degree of eccentricity.
【０００５】すなわち、例えば300 mmというように偏心
が少なすぎる場合には、浴の混合が充分に行われず、精
錬効果が大きく低下する。一方、偏心が大きすぎる場合
には、攪拌ガスが浸漬管外へ流出してしまい、浸漬管内
の攪拌力が著しく低下し、また浸漬管外へ流出した攪拌
ガスにより取鍋スラグが溢出するなどの危険が生じる。In other words, if the eccentricity is too small, for example, 300 mm, the mixing of the bath is not sufficiently performed, and the refining effect is greatly reduced. On the other hand, if the eccentricity is too large, the stirring gas flows out of the immersion tube, the stirring power in the immersion tube is significantly reduced, and the ladle slag overflows due to the stirring gas flowing out of the immersion tube. Danger arises.
【０００６】同様の攪拌ガスによる攪拌の例としては、
特開平１−156416号公報に示す方法があり、これによれ
ば底吹きポーラスプラグの偏心の程度を一定の範囲内に
限定することにより、効率のよい減圧精錬が可能である
としている。しかしながら、このポーラスプラグの設定
範囲についても以下のような問題があり、限られた装置
条件でしか有効ではない。[0006] As an example of stirring with a similar stirring gas,
There is a method disclosed in Japanese Patent Application Laid-Open No. 1-156416, and according to this method, by limiting the degree of eccentricity of a bottom blown porous plug within a certain range, efficient decompression refining can be performed. However, the setting range of the porous plug also has the following problems, and is effective only under limited device conditions.
【０００７】浸漬管中心からの偏心の程度の上限とし
て、 Ｘ／Ｒ≦ 0.33 Ｒ／Ｄ ただし、Ｒ: 浸漬管内径、 Ｄ: 取鍋内径、 Ｘ: 浸漬管投影面中心からのポーラスプラグの偏心 が設定されているが、浸漬管の浸漬深さが浅い場合、プ
ルーム（底吹きガス等の気泡が上昇する際に通過する領
域) の広がりを考慮していないため、浸漬管外への攪拌
ガスの流出の問題は解決できない。The upper limit of the degree of eccentricity from the center of the immersion tube is as follows: X / R ≦ 0.33 R / D, where R: inner diameter of the immersion tube, D: inner diameter of the ladle, X: eccentricity of the porous plug from the center of the immersion tube projection plane However, when the immersion depth of the immersion tube is shallow, the stirring gas to the outside of the immersion tube is not taken into account because the expansion of the plume (the area through which bubbles such as bottom-blown gas pass when rising) is not considered. The outflow problem cannot be solved.
【０００８】また、下限を Ｘ／Ｒ≧ 0.33 Ｒ／Ｄ− 0.07 としているが、この場合、流れの水平成分が偏心方向と
逆方向にも発生し、相殺されて充分な攪拌が不可能とな
る。なお、この例における具体的偏心量は高々450 mmで
あった。以上のように、従来の方法では効率的な攪拌は
不可能であった。Further, the lower limit is set to X / R ≧ 0.33 R / D−0.07. In this case, the horizontal component of the flow also occurs in the direction opposite to the eccentric direction, and the flow is canceled out, and sufficient stirring cannot be performed. . The specific amount of eccentricity in this example was at most 450 mm. As described above, efficient stirring was impossible with the conventional method.
【０００９】[0009]
【発明が解決しようとする課題】ここに、本発明の目的
は、攪拌ガスによる溶融金属、例えば溶鋼の攪拌効率を
大幅に向上させ、かつ攪拌ガスの浸漬管外への流出を効
果的に防止する方法を提供することである。SUMMARY OF THE INVENTION It is an object of the present invention to significantly improve the efficiency of stirring a molten metal, for example, molten steel, by a stirring gas and to effectively prevent the stirring gas from flowing out of an immersion tube. Is to provide a way to
【００１０】[0010]
【課題を解決するための手段】かかる目的達成のための
手段について、本発明者は、鋭意検討を重ねた結果、攪
拌ガス吹込み用の羽口の位置を適切に設定することによ
り、上記の課題が解決可能であることを知見し、本発明
を完成した。The present inventor has conducted intensive studies on the means for achieving the above object, and as a result, by appropriately setting the position of the tuyere for injecting the stirring gas, the above-mentioned means has been achieved. The inventors have found that the problem can be solved, and have completed the present invention.
【００１１】ここに、本発明の要旨とするところは、溶
融金属を収容する取鍋中に浸漬管を浸漬させて、浸漬管
内を減圧にして溶融金属を吸上げ、取鍋下部の浸漬管投
影面下に設置した羽口から攪拌ガスを吹込み溶融金属を
攪拌しながら取鍋精錬を行うに際して、前記羽口の設置
位置の取鍋中心よりの偏心距離Ｘが下記(1) 式の条件を
満たすようにすることを特徴とする、溶融金属の攪拌方
法である。Here, the gist of the present invention is that a dipping tube is immersed in a ladle containing molten metal, the pressure inside the dipping tube is reduced, and the molten metal is sucked up. When performing ladle refining while stirring the molten metal by blowing a stirring gas from the tuyere installed below the surface, the eccentric distance X from the center of the ladle at the installation position of the tuyere satisfies the condition of the following formula (1). A method of stirring molten metal, characterized by satisfying.
【００１２】[0012]
【数１】 (Equation 1)
【００１３】本発明の好適態様によれば、同時に複数の
羽口を設置する場合、取鍋中心と羽口位置を結ぶ線の中
心角αが 120°以内になるように設置すればよい。ま
た、上昇気泡の広がり角度は攪拌ガスの吹込み速度によ
って決まることから、各精錬条件を考慮した場合、換言
すれば、本発明はそれらの条件にもとづいて取鍋精錬を
行う場合の浸漬管の偏心の量、つまり設置位置の決定方
法である。According to a preferred aspect of the present invention, when a plurality of tuyeres are installed at the same time, the tuyere may be installed so that the central angle α of a line connecting the center of the ladle and the tuyere position is within 120 °. Further, since the spread angle of the rising bubbles is determined by the blowing speed of the stirring gas, when each refining condition is taken into account, in other words, the present invention provides a ladle refining system for performing ladle refining based on those conditions. This is a method of determining the amount of eccentricity, that is, the installation position.
【００１４】[0014]
【作用】次に、本発明の作用について添付図面を参照し
ながらさらに詳細に説明する。なお、以下の例にあって
は溶融金属として溶鋼を例にとって説明する。図１は、
本発明の概念図を示すものであり、図中、取鍋10に収容
された溶鋼12中に浸漬管14を浸漬させて、浸漬管内を減
圧にして溶鋼12を吸上げ、取鍋下部の浸漬管投影面下に
羽口16 (位置のみ示す) を設置して、攪拌ガスを吹込み
溶鋼を攪拌しながら取鍋精錬を行う。Next, the operation of the present invention will be described in more detail with reference to the accompanying drawings. In the following examples, molten steel will be described as an example of molten metal. FIG.
FIG. 1 is a conceptual diagram of the present invention, in which a dip tube 14 is immersed in molten steel 12 accommodated in a ladle 10, and the inside of the dip tube is depressurized to suck up the molten steel 12 and immerse the lower part of the ladle. The tuyere 16 (only the position is shown) is installed below the pipe projection surface, and ladle refining is performed while stirring gas is blown into the molten steel.
【００１５】吹込みガスは溶鋼内部を上昇しながら、徐
々に広がる。この広がり角をθとし、浸漬管下端からガ
ス吹込み位置までの深さをｈとしたとき、浸漬管下端の
高さへ到達したガスは、半径ｈ×tan θの広がりをも
つ。すなわち、ガスが浸漬管外へ流出しないためには、
ガス吹込み位置は浸漬管内周よりさらにｈ×tan θ以上
の内側に設置する必要がある。上昇気泡の広がり角は攪
拌ガスと溶融金属の密度比によって変わり、溶鋼の場合
には一般にθは20°程度である。すなわち、ガス吹込み
位置の中心よりの距離Ｘの最大値は浸漬管内径をＤとす
ると、The blown gas gradually spreads while rising inside the molten steel. Assuming that the spread angle is θ and the depth from the lower end of the immersion pipe to the gas injection position is h, the gas that has reached the height of the lower end of the immersion pipe has a radius h × tan θ. In other words, in order for the gas not to flow out of the immersion tube,
The gas injection position needs to be set further inside h × tan θ than the inner circumference of the immersion tube. The spread angle of the rising bubble varies depending on the density ratio between the stirring gas and the molten metal. In the case of molten steel, θ is generally about 20 °. That is, when the maximum value of the distance X from the center of the gas injection position is D,
【００１６】[0016]
【数２】 (Equation 2)
【００１７】で表されることが分かる。一方、Ｘが小さ
い場合、ガスの広がりが中心を越えると流れの水平成分
が二方向に生じるため、流れが分散して環状流が生じに
くくなる。したがって、水平成分のロスを回避するため
には、少なくともガスが浸漬管下端の高さに達したとき
に中心を越えないことが必要である。よって、この条件
は、It can be seen that On the other hand, when X is small, when the gas spreads beyond the center, a horizontal component of the flow is generated in two directions, so that the flow is dispersed and an annular flow is less likely to be generated. Therefore, in order to avoid the loss of the horizontal component, it is necessary that the gas does not cross the center at least when the gas reaches the height of the lower end of the dip tube. Therefore, this condition
【００１８】[0018]
【数３】 (Equation 3)
【００１９】なお、Ｘの下限値については、さらに望ま
しくは、The lower limit of X is more preferably
【００２０】[0020]
【数４】 (Equation 4)
【００２１】である。これは、後述の実施例においても
示されるとおり、均一混合時間がより一層短縮される範
囲となるからである。以上より、羽口の設置範囲は次の
通り規定される。## EQU1 ## This is because, as will be shown in the examples described later, the uniform mixing time is in a range in which the mixing time is further reduced. From the above, the installation range of the tuyere is defined as follows.
【００２２】[0022]
【数５】 (Equation 5)
【００２３】なお、羽口は底吹きポーラスプラグに限定
する必要はなく、浸漬ランスなどを用いてもよい。ただ
し、ランスの深さｈを取鍋内浴深さの50％以上確保する
ことが望ましい。The tuyere need not be limited to a bottom-blown porous plug, but may be a dipping lance or the like. However, it is desirable to secure the depth h of the lance at least 50% of the bath depth in the ladle.
【００２４】かくして本発明によれば、溶融金属の取鍋
精錬に際して溶融金属のより効果的な攪拌と脱ガス処理
が可能となり、例えば[C] 10ppm 以下、[H] 1ppm以下が
達成される。次に、本発明の作用効果について実施例に
よって具体的に説明する。Thus, according to the present invention, more effective stirring and degassing of the molten metal during ladle refining of the molten metal becomes possible, for example, [C] of 10 ppm or less and [H] of 1 ppm or less. Next, the operation and effect of the present invention will be specifically described with reference to examples.
【００２５】[0025]
【実施例】本例では図１に示す装置を使用し、浸漬管内
径2600mm、浸漬管下端からガス吹込み羽口までの深さ12
60mmとして、300 トンの溶鋼の脱ガス実験を行った。こ
こで、浸漬管に接続した真空槽内は脱ガス処理開始より
10分で2.5 Torrまで減圧し、さらに脱ガス処理開始後30
分後に１Torrまで減圧した。また、吹込んだ攪拌ガスは
２ Nm3/minのArガスであった。EXAMPLE In this example, the apparatus shown in FIG. 1 was used, and the inner diameter of the dip tube was 2600 mm and the depth from the lower end of the dip tube to the gas injection tuyere was 12 mm.
A degassing experiment for 300 tonnes of molten steel was conducted with a length of 60 mm. Here, the inside of the vacuum chamber connected to the immersion pipe is
Reduce the pressure to 2.5 Torr in 10 minutes, and 30
After one minute, the pressure was reduced to 1 Torr. The injected stirring gas was Ar gas at 2 Nm 3 / min.
【００２６】このとき、羽口の偏心距離Ｘを変化させ
て、溶鋼中の[C] 濃度、[H] 濃度の変化を調査した。た
だし、羽口数は１本であった。結果を表１に示す。ま
た、中心からの偏心量Ｘと均一混合時間の関係を図２に
グラフでもって示す。At this time, changes in the [C] concentration and [H] concentration in the molten steel were examined by changing the eccentric distance X of the tuyere. However, the number of tuyeres was one. Table 1 shows the results. FIG. 2 is a graph showing the relationship between the amount of eccentricity X from the center and the uniform mixing time.
【００２７】[0027]
【表１】 [Table 1]
【００２８】表１に示す結果より、偏心量Ｘが小さすぎ
ると均一混合時間が長く、脱Ｃ、脱Ｈとも不充分であっ
た (比較例１、２、３) 。一方、偏心量Ｘが大きすぎる
と均一混合時間は短くなるが、浸漬管外への攪拌ガスの
流出が生じるため、脱Ｃ、脱Ｈは不充分であった (比較
例４、５) 。これに対し、本発明により偏心量Ｘを適切
な範囲、例えば550 ≦Ｘ≦ 810(mm)とすることにより、
均一混合時間も短く、脱Ｃ、脱Ｈとも充分に行われた。From the results shown in Table 1, it was found that when the eccentric amount X was too small, the uniform mixing time was long, and the removal of C and H was insufficient (Comparative Examples 1, 2, and 3). On the other hand, if the amount of eccentricity X is too large, the uniform mixing time becomes short, but the outflow of the stirring gas to the outside of the immersion tube occurs, so that the removal of C and H was insufficient (Comparative Examples 4 and 5). On the other hand, according to the present invention, by setting the amount of eccentricity X to an appropriate range, for example, 550 ≦ X ≦ 810 (mm),
The uniform mixing time was short, and both C and H were sufficiently removed.
【００２９】次に、同様の装置において、複数の羽口よ
り合計２ Nm3/minのArを吹込んだ場合の同様の溶鋼の脱
ガス実験の結果を表２に示す。ただし、羽口位置はいず
れも中心からの偏心770 mmであり、取鍋中心と羽口位置
を結ぶ線の中心角αは120 度以内であった。図３に各羽
口の取付位置を図示する。図中２以上の羽口を設けたと
きのαの角度は20度以内に規制する。Next, Table 2 shows the results of similar molten steel degassing experiments when a total of 2 Nm 3 / min of Ar was blown from a plurality of tuyeres in the same apparatus. However, the tuyere position was 770 mm eccentric from the center, and the central angle α of the line connecting the ladle center and the tuyere position was within 120 degrees. FIG. 3 shows the mounting position of each tuyere. When two or more tuyeres are provided in the figure, the angle of α is restricted within 20 degrees.
【００３０】[0030]
【表２】 [Table 2]
【００３１】このとき、羽口数２本、３本のいずれの場
合にも、中心角 120°以内では脱ガスが充分に行われた
が (実施例４〜７) 、中心角が 120°より大きい場合、
脱ガスが不充分となった (比較例６〜８) 。At this time, in both cases of two or three tuyeres, degassing was sufficiently performed within the central angle of 120 ° (Examples 4 to 7), but the central angle was larger than 120 °. If
Degassing became insufficient (Comparative Examples 6 to 8).
【００３２】[0032]
【発明の効果】本発明により、浸漬管に溶融金属を吸い
上げる減圧精錬において、装置内の攪拌が充分に行わ
れ、脱ガス能が向上した。According to the present invention, in vacuum refining in which molten metal is sucked into a dip tube, stirring in the apparatus is sufficiently performed and degassing ability is improved.
【図１】本発明の概念を表す説明図である。FIG. 1 is an explanatory diagram illustrating the concept of the present invention.
【図２】羽口位置による均一混合時間変化を示すグラフ
である。FIG. 2 is a graph showing changes in uniform mixing time depending on tuyere positions.
【図３】取鍋底部における羽口の取付位置の説明図であ
る。FIG. 3 is an explanatory view of a mounting position of a tuyere at a bottom portion of a ladle;
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) C21C 7/10 C21C 7/00 C22B 9/04 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. 6 , DB name) C21C 7/10 C21C 7/00 C22B 9/04
Claims (2)
漬させて、浸漬管内を減圧にして溶融金属を吸上げ、取
鍋下部の浸漬管投影面下に設置した羽口から攪拌ガスを
吹込み溶融金属を攪拌しながら取鍋精錬を行うに際し
て、 前記羽口の設置位置の取鍋中心よりの偏心距離Ｘが下記
(1) 式の条件を満たすようにすることを特徴とする、溶
融金属の攪拌方法。 【数１】 1. An immersion pipe is immersed in a ladle for accommodating molten metal, the pressure inside the immersion pipe is reduced, and the molten metal is sucked up. When performing ladle refining while stirring molten metal, the eccentric distance X from the center of the ladle at the tuyere installation position is as follows:
A method for stirring molten metal, characterized by satisfying the condition of equation (1). (Equation 1)
中心と羽口位置を結ぶ線の中心角が 120°以内になるよ
うに設置することを特徴とする請求項１記載の溶融金属
の攪拌方法。2. The melting method according to claim 1, wherein, when a plurality of tuyeres are installed at the same time, the center angle of a line connecting the center of the ladle and the tuyere position is within 120 °. Metal stirring method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25820593A JP2929912B2 (en) | 1993-10-15 | 1993-10-15 | Stirring method of molten metal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25820593A JP2929912B2 (en) | 1993-10-15 | 1993-10-15 | Stirring method of molten metal |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07113114A JPH07113114A (en) | 1995-05-02 |
| JP2929912B2 true JP2929912B2 (en) | 1999-08-03 |
Family
ID=17316976
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25820593A Expired - Lifetime JP2929912B2 (en) | 1993-10-15 | 1993-10-15 | Stirring method of molten metal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2929912B2 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5603749A (en) * | 1995-03-07 | 1997-02-18 | Bethlehem Steel Corporation | Apparatus and method for vacuum treating molten steel |
| JP5800465B2 (en) * | 2010-03-31 | 2015-10-28 | 株式会社神戸製鋼所 | Manufacturing method of high cleanliness steel |
| CN112760506A (en) * | 2020-12-27 | 2021-05-07 | 上海交通大学安徽(淮北)陶铝新材料研究院 | System with electromagnetic stirring for controlling in-situ authigenic aluminum-based composite material through melt |
| CN112813279A (en) * | 2020-12-27 | 2021-05-18 | 上海交通大学安徽(淮北)陶铝新材料研究院 | System for controlling in-situ authigenic aluminum-based composite material through melt with continuous treatment |
| CN112808991A (en) * | 2020-12-27 | 2021-05-18 | 上海交通大学安徽(淮北)陶铝新材料研究院 | In-situ autogenous aluminum matrix composite material system with permanent magnet stirring function |
| CN112779435B (en) * | 2020-12-27 | 2021-12-14 | 上海交通大学安徽(淮北)陶铝新材料研究院 | Method for controlling in-situ authigenic aluminum-based composite material through melt with electromagnetic stirring |
| CN112779434A (en) * | 2020-12-27 | 2021-05-11 | 上海交通大学安徽(淮北)陶铝新材料研究院 | Method for in-situ self-growing aluminum-based composite material with permanent magnet stirring |
-
1993
- 1993-10-15 JP JP25820593A patent/JP2929912B2/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| 鉄と鋼、Ｖｏｌ．７９，Ｎｏ．８（１９９３）ＰＰ．９３４−９４０ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07113114A (en) | 1995-05-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2201364C (en) | Vacuum refining method for molten steel | |
| JP2929912B2 (en) | Stirring method of molten metal | |
| JP2002500273A (en) | Blower for molten metal gas treatment | |
| JP5855477B2 (en) | Hot metal refining method | |
| JP2915631B2 (en) | Vacuum refining of molten steel in ladle | |
| JPH07157816A (en) | Method for refining moltenmetal | |
| JP2002180124A (en) | Method for refining molten metal | |
| JP3290794B2 (en) | Molten steel refining method under reduced pressure | |
| JP3153048B2 (en) | Melting method of low nitrogen steel by low vacuum refining | |
| JP3550039B2 (en) | Powder desulfurization method of molten steel under reduced pressure and reaction vessel for powder desulfurization under reduced pressure | |
| JP2978045B2 (en) | Vacuum refining method for molten steel with high decarburization characteristics | |
| JPH02232314A (en) | Apparatus for refining molten steel under reduced pressure | |
| JP3052076B2 (en) | Decompression refining method excellent for decarburization | |
| JPH0488113A (en) | Method for refining molten steel | |
| JPH05311229A (en) | Ladle degassing treatment apparatus | |
| JP2819424B2 (en) | Manufacturing method of ultra-low carbon steel | |
| JP2998039B2 (en) | Manufacturing method of ultra-low carbon steel | |
| JP2988737B2 (en) | Manufacturing method of ultra-low carbon steel | |
| JPH08120324A (en) | Apparatus and method for vacuum-refining molten steel | |
| JP3252726B2 (en) | Vacuum refining method for molten steel | |
| JPH06322430A (en) | Vacuum refining method of molten metal | |
| JPH07268430A (en) | Immersion single pipe lance for pretreatment of molten iron | |
| JP2000192132A (en) | Vacuum refining apparatus of molten steel | |
| JPH0589443U (en) | Immersion pipe for molten steel treatment | |
| JPH0610027A (en) | Vacuum degassing refining method for molten metal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 19990420 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090521 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100521 Year of fee payment: 11 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110521 Year of fee payment: 12 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110521 Year of fee payment: 12 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120521 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120521 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130521 Year of fee payment: 14 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130521 Year of fee payment: 14 |
|
| R371 | Transfer withdrawn |
Free format text: JAPANESE INTERMEDIATE CODE: R371 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130521 Year of fee payment: 14 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130521 Year of fee payment: 14 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140521 Year of fee payment: 15 |
|
| EXPY | Cancellation because of completion of term |