JPS59153822A - Method for removing inclusion from molten steel - Google Patents
Method for removing inclusion from molten steelInfo
- Publication number
- JPS59153822A JPS59153822A JP2743383A JP2743383A JPS59153822A JP S59153822 A JPS59153822 A JP S59153822A JP 2743383 A JP2743383 A JP 2743383A JP 2743383 A JP2743383 A JP 2743383A JP S59153822 A JPS59153822 A JP S59153822A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- bubbles
- gas
- blowing
- diameter
- 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.)
- Pending
Links
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Continuous Casting (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【発明の詳細な説明】
属介在物を微細な気泡((よシ浮上除去する方法に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for removing metal inclusions by floating them into fine bubbles.
溶鋼中の介在物は、圧延され製品となった際、表面疵等
の原因となるため、連続鋳造用タンディラン−中で浮上
分離することが望ましく、浮上を促進するタンディツシ
ュせき等の工夫が従来なされている。Inclusions in molten steel can cause surface defects when rolled into products, so it is desirable to float and separate them in a tundish run for continuous casting. being done.
浮上分離の原理は、溶鋼と非金属介在物との比重差に基
づく浮力によるものであるが、浮上の速一度は、通常ス
トークスの法則に従い、比重差が同じであれば、径の大
きな粒子が浮上しやすいことが知られている。したがっ
て、径の小さな介在物粒子は、タンディツシュ中を溶鋼
が移動する時間内には浮上せず、そのまま、連続鋳造用
の鋳型内に流れ込むことになる。上記鋳型内においても
、これらの介在物粒子の浮上分離が行なわれるが、直径
数十ミクロン以下の微小介在物については、浮上除去が
困難であった。The principle of flotation separation is based on buoyancy based on the difference in specific gravity between molten steel and nonmetallic inclusions, but the speed of flotation usually follows Stokes' law, and if the difference in specific gravity is the same, particles with larger diameters will It is known to float easily. Therefore, inclusion particles with small diameters do not float up during the time that the molten steel moves in the tundish, but instead flow into the continuous casting mold as they are. Although these inclusion particles are floated and separated within the mold, it has been difficult to float and remove minute inclusions with a diameter of several tens of microns or less.
こうした微小介在物を浮上分離する方法としては、Ar
ガス等の気泡を多孔質耐火物等を使用して底部より
吹き込む方法が過去提案されている。As a method for floating and separating such minute inclusions, Ar
A method has been proposed in the past in which bubbles of gas or the like are injected from the bottom using a porous refractory.
即ち、気泡表面に捕えられた微小介在物を気泡の浮力で
浮上させる方法である。That is, this is a method in which minute inclusions caught on the surface of bubbles are floated by the buoyancy of the bubbles.
ところで、この方法をタンディツシュ内で行なうと、多
孔質耐火物等からの気泡径は敢闘と大きいので、介在物
を気泡表面で捕えるには多量匠吹き込みを行ない気泡の
総表面積を増加する必要があった。このように多量に気
体を吹き込むと、当然ながら、気泡径は気泡同士の合体
によってさらに成長し、かつ、吹込気体の浮力にてよる
強い溶鋼上昇流を生じる。この上昇流は必然的に周囲に
下降流を生じさせるため、結果的【では、攪拌流が形成
され介在物の浮上分離を著しく阻害するという欠点があ
った。By the way, when this method is carried out in a tundish, the diameter of the bubbles from the porous refractories etc. is extremely large, so in order to trap inclusions on the bubble surface, it is necessary to increase the total surface area of the bubbles by performing heavy blowing. Ta. When such a large amount of gas is blown into the molten steel, the diameter of the bubbles naturally increases as the bubbles coalesce, and the buoyancy of the blown gas causes a strong upward flow of molten steel. This upward flow inevitably generates a downward flow in the surroundings, resulting in the formation of an agitating flow, which has the drawback of significantly inhibiting the flotation and separation of inclusions.
この欠点を解消するため【では、吹込ガスの気泡径を小
さくし、かつ吹込量を少量にする必要があるが、多孔質
耐火物の気孔径を小さくしたとしても、気泡の合体(て
より大きく成長するので微細な気泡は得られない。また
、ノズルにより高速で吹き込めば、気泡の微細化は可能
ではあるが、吹き込み(で伴う攪拌力が犬さいので、タ
ンプイノシーのような底の浅い容器1ては不適轟である
。In order to eliminate this drawback, it is necessary to reduce the bubble diameter of the blown gas and the injection amount, but even if the pore diameter of the porous refractory is made small, the coalescence of the bubbles (the As the bubbles grow, it is not possible to obtain fine bubbles.Also, it is possible to make the bubbles finer by blowing at high speed with a nozzle, but since the stirring force associated with blowing is too small, it is difficult to obtain fine bubbles. It is inappropriate to do so.
本発明は、このような従来の微小介在物の除去方法にお
ける問題点を抜本的(て解消したものであってその要旨
は、加熱分解により微細な気泡を生成する直径3〜70
0ミクロンの粉体を吹き込むことを、特徴とするもので
ある。The present invention fundamentally solves the problems in the conventional method for removing microscopic inclusions, and the gist of the invention is that fine inclusions with a diameter of 3 to 70 mm are generated by thermal decomposition.
It is characterized by blowing in 0 micron powder.
以下本発明について詳細に説明する0
加熱分解により気泡を生成する物質としては、具体的に
例えば、FeCO3,MgCO3,CaCO3,Naz
CO3のような炭酸塩類やCa(OH)z、 Mg(O
H)zのような水酸化物が知られている。こうした化合
物を所定の粒径の粉体として吹き込むと、溶鋼中では瞬
時に加熱分解され約7000倍に体積増加してCO2ガ
ス、H2,02ガスを発生する。H2,02ガスは溶鋼
との反応性が大きいので、C’02ガスを発生する炭酸
塩類が望ましい。The present invention will be described in detail below. Examples of substances that generate bubbles by thermal decomposition include FeCO3, MgCO3, CaCO3, Naz
Carbonates such as CO3, Ca(OH)z, Mg(O
Hydroxides such as H)z are known. When such a compound is injected as a powder with a predetermined particle size, it is instantaneously thermally decomposed in molten steel, increasing its volume by about 7000 times and generating CO2 gas and H2,02 gas. Since H2,02 gas is highly reactive with molten steel, carbonates that generate C'02 gas are desirable.
第1図は誘導溶解炉による76.2θ℃の溶鋼の実験の
一例であり、 CaCO3をArガスをキャリヤーガ
スとして固気比Sで一定量吹込んだ時の気泡径(粉体径
の約75倍に相当)と介在物の補集効率との関係を指数
表示したものである″。図より明らかなように粉体径に
は、好ましい範囲が存在する。これは、前述したように
一定のガス量の場合気泡径が小さいほど大きな表面積を
有するので、粉体径は、小さい方が好ましり、700ミ
クロン以下が適当である。一方、気泡径が微小すぎると
気泡自体が浮上しないためタンディツシュ内で十分に浮
上するよう粉体径は、3ミクロン以上が適当である。Figure 1 shows an example of an experiment on molten steel at 76.2θ℃ using an induction melting furnace. This is an index representation of the relationship between the particle diameter (equivalent to twice the diameter) and the inclusion collection efficiency.As is clear from the figure, there is a preferable range for the powder diameter. In terms of gas volume, the smaller the bubble diameter, the larger the surface area, so the smaller the powder diameter is, the more suitable is 700 microns or less.On the other hand, if the bubble diameter is too small, the bubbles themselves will not float, so the tundish The diameter of the powder is suitably 3 microns or more so that it can float sufficiently within the container.
まだ、定性的ではあるが、気泡径が小さいほど吹込中の
湯面の変動は少なかった。即ち気泡上昇に伴う攪拌流は
見られなかった。Although it is still qualitative, the smaller the bubble diameter, the less the fluctuation of the melt level during blowing. That is, no stirring flow accompanying the rise of bubbles was observed.
これらの微粉体を吹込むC(は、公知の粉体吹込装置し
てより圧送し、ノズルを介して溶鋼中に吹き込めば良い
。固気比、即ち吹込粉体重量を吹込用気体重量で除した
数が小さければ、実質的1(従来の気体吹込と大差ない
ので、固気トヒは3以上が望ましい。吹込用気体として
は、Arガスのような不活性ガスが望まし論。また、粉
体を溶鋼中(で分散しやすくするため吹込部はノズル形
状とし、高速で吹き込むことが望ましく気泡同士の合体
防止、ガス生成時の吸熱(てよる溶鋼の局部冷却を防止
することができる。この場合、吹込(て要するガス量は
僅かであるので、溶鋼攪拌の影響は少々い。しかし、鋼
種等により大量に気泡吹込を要する場合には、固気比を
大きくとることが望ましい。These fine powders can be blown into the molten steel by using a known powder blowing device and blown into the molten steel through a nozzle. If the number is small, it is practically 1 (it is not much different from conventional gas blowing, so it is desirable that the solid air pressure is 3 or more. As the blowing gas, it is desirable to use an inert gas such as Ar gas. In order to make it easier to disperse the molten steel into the molten steel, the blowing section should be shaped like a nozzle, and it is desirable to blow at high speed to prevent coalescence of bubbles and to prevent local cooling of the molten steel due to heat absorption during gas generation. In this case, since the amount of gas required for blowing is small, the effect of stirring the molten steel is small. However, if a large amount of bubble blowing is required depending on the steel type, it is desirable to have a large solid-air ratio.
吹込の場所および吹込ノズルの本数は使用するタンプイ
ノシーの形状、溶鋼流速度等によって最適位置、本数を
決定すべきであるが、位置としては・取鍋直下の注入溶
鋼流の影響を受けに<<、シかも微小介在物の浮上時間
を十分に確保できる場所してすべきである。吹込ノズル
の本数はタンティッシュの巾、長さに応じて複数化する
ことが望ましい。まだ、吹込ノズルは、底部吹込よりも
ランスノズルによる上吹法が簡便であり望ましい。The optimum position and number of blowing nozzles should be determined depending on the shape of the tamper injector used, the molten steel flow velocity, etc.; However, the location should be such that sufficient floating time for minute inclusions can be ensured. It is desirable to use a plurality of blowing nozzles depending on the width and length of the tongue tissue. However, the top blowing method using a lance nozzle is simpler and more desirable than the bottom blowing nozzle.
次に本発明法の実施例により、従来法に対する効果を明
らかにする。Next, the effects of the present invention method over the conventional method will be clarified through examples.
実施例
長さ3m、巾1m溶鋼量/3;T(1620℃)のタン
プイノシーを用いて、本発明法の効果確認を行なった。EXAMPLE The effectiveness of the method of the present invention was confirmed using a tamper innovator with a length of 3 m and a width of 1 m, molten steel amount/3; T (1620° C.).
鋼種はアルミキルド鋼を用い鋳造後の試験片中の介在物
−lにより従来法との比較を行なった。Aluminum killed steel was used as the steel type, and comparisons were made with the conventional method based on inclusions-1 in the test pieces after casting.
吹込粉体は平均径50ミクロンの炭酸鉄(FeCO3)
を用い!孔のランスノズルを浸漬して行々つだ。The blown powder is iron carbonate (FeCO3) with an average diameter of 50 microns.
Use! Immerse the lance nozzle in the hole and proceed.
気泡径は7θθ〜に86ミクロンであった。The bubble diameter was 86 microns at 7θθ.
本発明法と従来法との比較衣
(表中の数字は固気比を除き指数表示)上表に示すよう
に、本発明法によれば、少量の吹込ガス量で介在物量を
大巾に減少できることが判明した。Comparison of the method of the present invention and the conventional method (The numbers in the table are expressed as indexes except for the solid-air ratio) As shown in the table above, according to the method of the present invention, the amount of inclusions can be greatly reduced with a small amount of blown gas. It turns out that it can be reduced.
以上本発明を適用することにより、従来の鉄鋼製゛造プ
ロセスを大巾に変更することなく簡便、かつ効率的1て
品質向上を図ることができる。By applying the present invention as described above, it is possible to simply and efficiently improve quality without making any major changes to the conventional steel manufacturing process.
・λ1図は実験結果の一例を示すグラフである。 ・The λ1 diagram is a graph showing an example of experimental results.
Claims (1)
において、加熱分解により微論な気泡を生成する直径3
〜/θθミクロンの粉体をタンディッシー内溶鋼中Vζ
吹き込むことを特徴とする溶鋼中介在物の除去方法。In a method for removing inclusions in molten steel in a tundish for steelmaking, a diameter 3.
~/θθ micron powder in molten steel in Tandisy Vζ
A method for removing inclusions in molten steel, characterized by blowing.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2743383A JPS59153822A (en) | 1983-02-21 | 1983-02-21 | Method for removing inclusion from molten steel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2743383A JPS59153822A (en) | 1983-02-21 | 1983-02-21 | Method for removing inclusion from molten steel |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS59153822A true JPS59153822A (en) | 1984-09-01 |
Family
ID=12220973
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP2743383A Pending JPS59153822A (en) | 1983-02-21 | 1983-02-21 | Method for removing inclusion from molten steel |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS59153822A (en) |
-
1983
- 1983-02-21 JP JP2743383A patent/JPS59153822A/en active Pending
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