JPH10193050A - Method for continuously casting molten metal - Google Patents
Method for continuously casting molten metalInfo
- Publication number
- JPH10193050A JPH10193050A JP9000198A JP19897A JPH10193050A JP H10193050 A JPH10193050 A JP H10193050A JP 9000198 A JP9000198 A JP 9000198A JP 19897 A JP19897 A JP 19897A JP H10193050 A JPH10193050 A JP H10193050A
- Authority
- JP
- Japan
- Prior art keywords
- molten metal
- refractory
- flux
- circulation tank
- wall
- 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
Landscapes
- Continuous Casting (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、取鍋に保持した溶
融金属を、タンディッシュに連続的に供給して非金属介
在物を浮上分離し、次いでこの非金属介在物の低減され
た溶融金属を上下開放の水冷鋳型に連続的に注湯して鋳
片とする溶融金属の連続鋳造方法の改良に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten metal held in a ladle, which is continuously supplied to a tundish to separate non-metallic inclusions by flotation, and then to reduce the molten metal with reduced nonmetallic inclusions. The present invention relates to an improved method for continuously casting molten metal into a slab by continuously pouring a molten metal into a vertically cooled water-cooled mold.
【０００２】[0002]
【従来の技術】従来から溶融金属として例えば、溶鋼の
連続鋳造に際し、溶鋼段階で非金属介在物を除去するた
めに、タンディッシュでの処理が種々工夫されている。
例えば特開平1-312024号公報には、図７および図８に示
すように、取鍋１内に保持した溶鋼２をロングノズル３
を介してタンディッシュ４が備えた円筒状の回流槽５に
注湯し、この回流槽５の外周に沿って配設された半円状
の回転磁場発生装置６によって回流槽５内の溶鋼２を高
い回転数で水平回転させる溶融金属中の非金属介在物の
除去装置が開示されている。この水平回転流による攪拌
エネルギーによって、非金属介在物の遠心分離効果に加
えて非金属介在物の合体、凝集が起こり、非金属介在物
が粗大化され、この粗大化効果によって、通常、浮上に
よって分離することができない小さな非金属介在物の大
型化を可能にするものである。2. Description of the Related Art Conventionally, in the continuous casting of molten steel, for example, as a molten metal, various treatments with a tundish have been devised in order to remove nonmetallic inclusions at the molten steel stage.
For example, Japanese Unexamined Patent Publication No. 1-312024 discloses that a molten steel 2 held in a ladle 1 is a long nozzle 3 as shown in FIGS.
The molten steel 2 in the circulation tank 5 is poured by a semicircular rotating magnetic field generator 6 arranged along the outer periphery of the circulation tank 5 through the tundish 4. There is disclosed an apparatus for removing non-metallic inclusions in a molten metal by horizontally rotating the metal at a high rotational speed. Due to the stirring energy by this horizontal rotating flow, in addition to the effect of centrifugal separation of non-metallic inclusions, coalescence and aggregation of non-metallic inclusions occur, and the non-metallic inclusions are coarsened. It is intended to increase the size of small non-metallic inclusions that cannot be separated.
【０００３】この回流槽５内で大型化された非金属介在
物は、溶鋼２と共に連通口８を介してタンディッシュ４
が備えた浮上槽９に流入する。浮上槽９内に流入した溶
鋼２中の粗大化された非金属介在物は、溶鋼２から浮上
分離して高塩基度フラックス10に吸収され、非金属介在
物の低減された溶鋼２は、浸漬ノズル11を介して上下開
放の水冷鋳型12に連続的に供給されて鋳片13が鋳造され
る。また特開平3-110059号公報には、第一容器で溶融金
属に水平回転流を与えた後に、第２容器で溶融金属を加
熱する不純物の除去手段が提案されている。[0003] Non-metallic inclusions which have been enlarged in the circulation tank 5 together with the molten steel 2 are connected to the tundish 4 through a communication port 8.
Flows into the floating tank 9 provided with the above. The coarse non-metallic inclusions in the molten steel 2 flowing into the levitation tank 9 float and separate from the molten steel 2 and are absorbed by the high basicity flux 10, and the molten steel 2 with reduced non-metallic inclusions is immersed. The slab 13 is continuously supplied to the vertically open water-cooled mold 12 through the nozzle 11 to be cast. Japanese Patent Application Laid-Open No. 3-110059 proposes a means for removing impurities by applying a horizontal rotating flow to a molten metal in a first container and then heating the molten metal in a second container.
【０００４】しかしながら、前記のようなタンディッシ
ュや溶融金属容器では、図７における回流槽５内の雰囲
気や溶鋼２から分離された非金属介在物や浮上スラグ17
によって溶鋼２が酸化されるため、目的とする非金属介
在物の少ない高清浄鋼が得られないという問題点があっ
た。この問題点の一般的な対策としては、高塩基度フラ
ックスを添加して、スラグや非金属介在物を吸収させて
無害化すると共に雰囲気から溶鋼への酸素の供給を抑制
する方法がとられている。しかしながらこの方法を前記
タンディッシュ４が備えた回流槽５に適用した場合、回
流槽５内で浮上分離した浮上スラグ17（図７参照）に非
金属介在物吸収能の大きい高塩基度フラックスを添加し
て形成された高塩基度スラグ７（図９参照) が溶鋼２の
水平回転流に引きずられて回転する。このため、回流槽
５の内壁耐火物近傍で高塩基度スラグ７が攪拌され、高
塩基度スラグ７により回流槽５を形成する内壁耐火物と
の間に低融点化合物を生成する化学反応による溶損部16
の溶損度合いが増加し、タンディッシュ４の耐火物寿命
が極端に低下して耐火物コストを考慮すると経済的効果
がなく実質的に適用困難であった。However, in such a tundish or molten metal container, non-metallic inclusions and floating slag 17 separated from the atmosphere in the circulation tank 5 and the molten steel 2 in FIG.
As a result, the molten steel 2 is oxidized, so that there is a problem in that a high-purity steel with few nonmetallic inclusions as a target cannot be obtained. As a general countermeasure against this problem, a method has been adopted in which a high basicity flux is added to absorb slag and nonmetallic inclusions to make them harmless and to suppress the supply of oxygen from the atmosphere to molten steel. I have. However, when this method is applied to the circulation tank 5 provided in the tundish 4, a high basicity flux having a large nonmetallic inclusion absorption capacity is added to the floating slag 17 (see FIG. 7) floated and separated in the circulation tank 5. The thus formed high basicity slag 7 (see FIG. 9) is dragged by the horizontal rotating flow of the molten steel 2 and rotates. For this reason, the high basicity slag 7 is stirred near the inner wall refractory of the circulation tank 5, and the high basicity slag 7 is melted by the chemical reaction that generates a low melting point compound with the inner wall refractory forming the circulation tank 5. Lost part 16
And the life of the refractory of the tundish 4 was extremely reduced, so that considering the cost of the refractory, there was no economic effect and it was practically difficult to apply.
【０００５】[0005]
【発明が解決しようとする課題】内壁耐火物の化学的な
溶損に対して、取鍋では一般的にフラックスの組成を調
整して取鍋耐火物を保護し、その寿命を延ばす方法（通
称、スラグコントロール法という）が知られている。こ
の方法の原理は、溶液中への溶質の溶解が、溶質の濃度
を上げることにより抑制され、さらに溶質濃度を飽和濃
度以上にすれば溶出が完全に抑えられることにある。In order to protect the ladle refractory from chemical erosion of the inner wall refractory, the composition of the flux is generally adjusted in the ladle to protect the ladle refractory and extend the life of the ladle. , A slag control method) is known. The principle of this method is that the dissolution of a solute in a solution is suppressed by increasing the concentration of the solute, and the elution is completely suppressed if the solute concentration is set to a saturated concentration or more.
【０００６】このスラグコントロール法を利用した技術
としては、例えば特開昭64-28316号公報に開示されたも
のがある。それは取鍋内の溶鋼上にスラグを浮上させて
その溶鋼をスラグ精錬する取鍋精錬法において、取鍋の
内壁耐火物がスラグと接触する可能性のある部分をマグ
ネシア含有れんがで形成すると共に、スラグ中に添加す
る酸化マグネシウムの量をそのスラグ組成における飽和
量以上とする方法である。As a technique using the slag control method, for example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 64-28316. That is, in the ladle refining method of slag refining the molten steel by floating the slag on the molten steel in the ladle, the refractory inside wall of the ladle is likely to come into contact with the slag with the magnesia-containing brick, This is a method in which the amount of magnesium oxide added to the slag is equal to or more than the saturation amount in the slag composition.
【０００７】しかしながら、溶鋼の攪拌に伴ってフラッ
クスも攪拌される取鍋精錬法と異なり、従来のタンディ
ッシュではフラックスが殆ど攪拌されないため、タンデ
ィッシュを形成する内壁耐火物のフラックス中への溶出
が起こっても、耐火物近傍のフラックス中の耐火物成分
の濃度がすぐに飽和して溶出が止まるので、殆ど問題に
はならず、スラグコントロール法を適用しないのが常識
であった。However, unlike the ladle refining method in which the flux is also stirred with the molten steel, the flux is hardly stirred in the conventional tundish, so that the refractory on the inner wall forming the tundish is eluted into the flux. Even if it occurs, the concentration of the refractory component in the flux near the refractory is immediately saturated and the elution stops, so there is almost no problem, and it is common sense that the slag control method is not applied.
【０００８】本発明は、回流槽と、該回流槽に連通され
溶融金属中の非金属介在物を浮上分離させる浮上槽を備
えるタンディッシュにおいて回流槽に内壁耐火物に溶損
を生じることなく、再酸化防止用フラックスの添加を可
能として、非金属介在物の少ない高清浄度鋼を得ること
ができる溶融金属の連続鋳造方法を提供することを目的
とするものである。According to the present invention, there is provided a tundish having a circulation tank and a floating tank which communicates with the circulation tank and floats and separates nonmetallic inclusions in the molten metal without causing melting of the refractory on the inner wall of the circulation tank. It is an object of the present invention to provide a continuous casting method of molten metal capable of adding a flux for preventing re-oxidation and obtaining a high-cleanliness steel with few nonmetallic inclusions.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、回流槽５
および浮上槽９を備えたタンディッシュ４においては、
図９に示すように回流槽５内に高塩基度フラックスを添
加した場合、形成された高塩基度スラグ７が、溶鋼２の
水平回転流に引きずられて回転することを知見した。ま
た、タンディッシュ４における回流槽５の内壁耐火物が
溶損する主たる原因がこの高塩基度スラグ７の水平方向
への回転流に伴い、内壁耐火物との間に発生する乱流エ
ネルギーの増加により、耐火物成分の拡散速度が増加す
ることにあることを究明した。Means for Solving the Problems The present inventors have developed a circulation tank 5.
And in the tundish 4 having the floating tank 9,
As shown in FIG. 9, it was found that when a high basicity flux was added into the circulation tank 5, the formed high basicity slag 7 was dragged by the horizontal rotating flow of the molten steel 2 and rotated. The main cause of the erosion of the refractory on the inner wall of the circulation tank 5 in the tundish 4 is caused by an increase in turbulence energy generated between the refractory on the inner wall and the high-basicity slag 7 due to the rotating flow of the high basicity slag 7 in the horizontal direction. It has been found that the diffusion rate of the refractory component is increased.
【００１０】本発明は、前記のような知見に基づいてな
されたものであり、従来の回流槽および浮上槽を備えた
タンディッシュにスラグコントロール法を適用しても回
流槽を形成する内壁耐火物がフラックス中へ溶出するの
を防止するものであり、その要旨とするところは下記の
通りである。前記目的を達成するための請求項１記載の
本発明は、電磁力によって溶融金属に水平回転流を生成
させて非金属介在物を粗大化させる円筒型の回流槽と該
回流槽に連通され溶融金属中の非金属介在物を浮上分離
させる浮上槽とを備えるタンディッシュに取鍋に保持し
た溶融金属を連続的に供給して非金属介在物を浮上分離
し、次いでこの非金属介在物の低減された溶融金属を上
下開放の水冷鋳型に連続的に注湯して鋳片とする溶融金
属の連続鋳造方法において、前記回流槽内の溶融金属上
に形成する非金属介在物の吸収能を有するフラックス層
の少なくとも該回流槽を形成する内壁耐火物と接する部
分の組成を耐火材主成分と同一の成分を飽和溶解度以上
に含有する組成としたことを特徴とする溶融金属の連続
鋳造方法である。[0010] The present invention has been made based on the above-mentioned findings, and has a refractory material having an inner wall that forms a circulation tank even when a slag control method is applied to a tundish having a conventional circulation tank and a floating tank. Is prevented from being eluted into the flux, and the gist thereof is as follows. In order to achieve the above object, the present invention provides a cylindrical circulating tank for generating a horizontal rotating flow in a molten metal by electromagnetic force to coarsen nonmetallic inclusions, and is connected to the circulating tank for melting. A flotation tank that floats and separates non-metallic inclusions in metal is supplied continuously to a tundish with molten metal held in a ladle to float and separate non-metallic inclusions, and then reduce this non-metallic inclusion. In a continuous casting method of molten metal as a slab by continuously pouring the melted metal into a vertically open water-cooled mold, the method has an ability to absorb nonmetallic inclusions formed on the molten metal in the circulation tank. A continuous casting method for molten metal, characterized in that a composition of at least a portion of a flux layer in contact with an inner wall refractory forming the circulation tank has a composition containing the same component as a main component of a refractory material at a saturation solubility or higher. .
【００１１】請求項２記載の本発明は、電磁力によって
溶融金属に水平回転流を生成させて非金属介在物を粗大
化させる円筒型の回流槽と該回流槽に連通され溶融金属
中の非金属介在物を浮上分離させる浮上槽とを備えるタ
ンディッシュに取鍋に保持した溶融金属を連続的に供給
して非金属介在物を浮上分離し、次いでこの非金属介在
物の低減された溶融金属を上下開放の水冷鋳型に連続的
に注湯して鋳片とする溶融金属の連続鋳造方法におい
て、回流槽内の溶融金属上に、該回流槽を形成する内壁
耐火物の耐火材主成分と同一の成分を飽和溶解度未満に
含有する組成とした非金属介在物吸収能を有するフラッ
クスを初めに添加し、次に前記回流槽を形成する内壁耐
火物の近傍に、該内壁耐火物の耐火材主成分と同一の成
分を飽和溶解度以上に含有する組成とした非金属介在物
吸収能を有するフラックスを添加することを特徴とする
溶融金属の連続鋳造方法である。According to the present invention, there is provided a cylindrical circulating tank for generating a horizontal rotating flow in a molten metal by electromagnetic force to coarsen nonmetallic inclusions, and a circulating tank connected to the circulating tank for controlling a non-metal in the molten metal. A floating tank for floating and separating metal inclusions is supplied continuously to a tundish with molten metal held in a ladle to float and separate nonmetallic inclusions, and then the molten metal with reduced nonmetallic inclusions In a continuous casting method of molten metal into a slab by continuously pouring into a vertically cooled water-cooled mold, on the molten metal in the circulating tank, the refractory material main component of the inner wall refractory forming the circulating tank First, a flux having a nonmetallic inclusion absorption capacity having a composition containing the same component less than the saturation solubility is added, and then the refractory material of the inner wall refractory is formed near the inner wall refractory forming the circulation tank. More than the saturation solubility of the same component as the main component A continuous casting method of molten metal, which comprises adding a flux having a non-metallic inclusions absorption capacity for using the composition containing.
【００１２】請求項３記載の本発明は、回流槽内の溶融
金属上に初めに添加するフラックスの比重よりも次に回
流槽の内壁耐火物近傍に添加するフラックスの比重を大
とすることを特徴とする請求項２記載の溶融金属の連続
鋳造方法である。請求項４記載の本発明は、取鍋に保持
した用金属をロングノズルを介して回流槽の中心部に供
給することを特徴とする請求項１、２または３記載の溶
融金属の連続鋳造方法である。According to a third aspect of the present invention, the specific gravity of the flux added to the vicinity of the refractory on the inner wall of the circulation tank is larger than the specific gravity of the flux added first to the molten metal in the circulation tank. A method for continuously casting molten metal according to claim 2, characterized in that: According to a fourth aspect of the present invention, there is provided the method for continuously casting molten metal according to the first, second or third aspect, wherein the metal held in the ladle is supplied to a central portion of the circulation tank through a long nozzle. It is.
【００１３】[0013]
【発明の実施の形態】以下本発明の実施の形態を図面に
基づいて説明する。なお、本発明において図７および図
８に示す従来の連続鋳造装置と同じものは同一符合を付
して説明が重複するのを省略する。本発明の第１の発明
によるスラグコントロール法を用いた場合、図１、図２
に示すように回流槽５内の溶鋼２上に添加した飽和フラ
ックス15は、溶鋼２中の非金属介在物吸収能を有すると
共に、回流槽５を形成する内壁耐火物の耐火材主成分と
同一の成分を飽和溶解度以上に含有する組成であるた
め、内壁耐火物を形成する耐火材主成分の溶出が防止で
き、内壁耐火物の溶損が低減される。しかし、回流槽５
内の飽和フラックス15が固化する、いわゆる皮張りの状
態が発生しやすいことが分かった。この状態が発生する
と連続鋳造における取鍋交換時やトラブル発生時に必要
となる回流槽５中心部のロングノズル３の引き上げや浸
漬を行うことが困難となり、皮張りの程度が大きい場合
には連続鋳造を中止せざるを得ない場合がある。Embodiments of the present invention will be described below with reference to the drawings. In the present invention, the same components as those of the conventional continuous casting apparatus shown in FIGS. 7 and 8 are denoted by the same reference numerals, and the description thereof will not be repeated. 1 and 2 when the slag control method according to the first invention of the present invention is used.
As shown in the figure, the saturated flux 15 added to the molten steel 2 in the circulation tank 5 has the ability to absorb nonmetallic inclusions in the molten steel 2 and is the same as the main component of the refractory material of the refractory on the inner wall forming the circulation tank 5. Since the composition contains the above component at a saturation solubility or higher, elution of a main component of the refractory material forming the inner wall refractory can be prevented, and erosion of the inner wall refractory can be reduced. However, the circulation tank 5
It has been found that the so-called skinning state in which the saturated flux 15 in the inside solidifies easily occurs. When this state occurs, it becomes difficult to pull up and immerse the long nozzle 3 at the center of the circulation tank 5 which is necessary at the time of ladle replacement or trouble occurrence in continuous casting. May have to be stopped.
【００１４】本発明者らは、回流槽５内の溶鋼２が、電
磁力によって水平方向に回転するのにつれて周辺部の飽
和フラックス15は回転するが、その回転中心部は殆ど回
転しておらず、中心部の飽和フラックス15の上面の温度
が雰囲気による抜熱や放熱により低下して固相が生成し
易く、その結果、皮張り状態を発生することを究明し
た。したがって回流槽５を形成する内壁耐火物の耐火材
主成分と同一の成分を飽和溶解度以上に含有する組成と
した飽和フラックス15は、温度の低下により固相を生成
し易く、皮張りが起こり易い組成になっていると考えら
れる。一方、該成分が飽和濃度に満たないフラックスで
は、温度が低下しても該成分が飽和するまでは固相を生
成しないため、当然、皮張りが起こり難い組成となって
いる。As the molten steel 2 in the circulation tank 5 rotates in the horizontal direction by the electromagnetic force, the inventors rotate the saturated flux 15 in the peripheral portion, but the rotation center portion hardly rotates. It has been found that the temperature of the upper surface of the saturated flux 15 at the center is lowered by heat removal and heat radiation due to the atmosphere, so that a solid phase is easily generated, and as a result, a skinning state is generated. Therefore, the saturated flux 15 having a composition containing the same component as the main component of the refractory material of the refractory of the inner wall forming the circulation tank 5 at a temperature higher than the saturation solubility easily generates a solid phase due to a decrease in temperature and easily causes skinning. It is considered to be a composition. On the other hand, in the case of a flux in which the component is less than the saturation concentration, a solid phase is not generated until the component is saturated even if the temperature decreases, so that the composition naturally has a tendency to hardly cause skinning.
【００１５】したがって、内壁耐火物溶損の原因となる
回流槽５内の湯面外周部に存在するフラックス組成を、
内壁耐火物の耐火材主成分と同一の成分について飽和状
態とし、一方、回流槽内の湯面中心部、すなわちロング
ノズル３近傍のフラックス組成を、該成分濃度について
飽和濃度未満にすることによって内壁耐火物の溶損とロ
ングノズル３近傍の皮張りを同時に抑制することが可能
となる。Therefore, the flux composition existing on the outer periphery of the molten metal surface in the circulation tank 5 which causes the refractory erosion of the inner wall is determined as follows:
By making the same component as the main component of the refractory material of the inner wall refractory into a saturated state, while making the flux composition in the central part of the molten metal surface in the circulation tank, that is, near the long nozzle 3, the concentration of the component less than the saturated concentration, It is possible to simultaneously suppress the erosion of the refractory and the skinning near the long nozzle 3.
【００１６】本発明の第２の発明は、前記の知見に基づ
いてなされたものであり、以下に、本発明の第２の発明
によって得られる作用を説明する。図３に示すようにタ
ンディッシュ４が備えた回流槽５内の溶鋼２の自由表面
は、回転磁場発生装置６の電磁力によって生成した水平
回転流に伴う遠心力の影響により、回流槽５の中心部で
窪みが形成される。一般的にフラックスの比重は溶鋼と
比較して軽いため、遠心分離効果により初めに添加した
未飽和フラックス14はこの窪み部分に流れ込むことにな
る。このため、後から回流槽５の内壁耐火物近傍（外周
部近傍）にもう一方の飽和フラックス15を添加した場
合、２種類のフラックスは殆ど混合することなく回流槽
５の中心部と外周部に分離した状態で添加することが可
能になる。[0016] The second invention of the present invention has been made based on the above findings, and the operation obtained by the second invention of the present invention will be described below. As shown in FIG. 3, the free surface of the molten steel 2 in the circulation tank 5 provided in the tundish 4 is affected by the centrifugal force accompanying the horizontal rotating flow generated by the electromagnetic force of the rotating magnetic field generator 6. A depression is formed at the center. Generally, the specific gravity of the flux is lighter than that of the molten steel, so that the unsaturated flux 14 added first due to the centrifugal effect flows into this hollow portion. For this reason, when the other saturated flux 15 is added near the inner wall refractory (near the outer peripheral portion) of the circulation tank 5 later, the two types of fluxes are hardly mixed, and are added to the center and the outer periphery of the circulation tank 5. It can be added in a separated state.
【００１７】前述のように、回流槽５内では取鍋精錬容
器とは異なり、未飽和フラックス14は殆ど回転せず外周
部近傍に添加された飽和フラックス15と互いに混合され
る攪拌がないため、中心部に存在するフラックス成分濃
度は長時間にわたって飽和濃度以下に維持され、回流槽
５の中心部で皮張りを起こすことなく非金属介在物を吸
収することが可能となる。As described above, unlike the ladle refining vessel, in the circulation tank 5, the unsaturated flux 14 hardly rotates and there is no stirring mixed with the saturated flux 15 added near the outer periphery. The concentration of the flux component existing in the central portion is maintained at or below the saturation concentration for a long time, and the nonmetallic inclusions can be absorbed without causing skinning in the central portion of the circulation tank 5.
【００１８】ところで、飽和フラックス15は回流槽５内
に添加、溶融された後にも耐火材主成分と同一成分の固
相が存在する。飽和フラックス15は水平回転する溶鋼２
に引きずられて溶鋼回転方向と同じ方向に水平回転する
ため、耐火材主成分と同一成分の固相には（ΔρＶ）r
ω2 の遠心力が作用することになる。この作用により、
耐火材主成分と同一成分の固相の密度が飽和フラックス
15の液相の比重と比較して大きい場合には遠心力により
固相は外周方向に移動し、逆に小さい場合には回転中心
方向に移動することになる。ここで、Δρは耐火材主成
分と同一成分の一つの固相と飽和フラックス15の液相と
の密度差、Ｖはその固相の体積、ｒは回転中心からその
固相までの距離、ωはその固相の回転運動における角速
度である。Incidentally, even after the saturated flux 15 is added and melted in the circulation tank 5, a solid phase having the same component as the main component of the refractory material exists. The saturated flux 15 is molten steel 2 rotating horizontally.
To the horizontal direction in the same direction as the molten steel rotation direction, the solid phase of the same component as the main component of the refractory material has (ΔρV) r
A centrifugal force of ω 2 acts. By this action,
The solid phase density of the same component as the main refractory material is saturated flux
When the specific gravity is larger than the specific gravity of the liquid phase of No. 15, the solid phase moves toward the outer periphery due to the centrifugal force, and when the specific gravity is small, it moves toward the rotation center. Here, Δρ is the density difference between one solid phase of the same component as the refractory material main component and the liquid phase of the saturated flux 15, V is the volume of the solid phase, r is the distance from the rotation center to the solid phase, ω Is the angular velocity in the rotational motion of the solid phase.
【００１９】本発明の第３の発明はこの知見に基づいて
なされたものであり、回流槽５内の溶鋼２上に、最初に
添加する高塩基度の未飽和フラックス14の比重よりも、
次に該回流槽５を形成する内壁耐火物の近傍に添加する
飽和フラックス15の比重を大とするものである。内壁耐
火物の近傍に添加する飽和フラックス15の比重を、高塩
基度の未飽和フラックス14に比較して大きくすることに
より、回流槽５を形成する内壁耐火物と同一成分の固相
が外周部に集中し、さらに中心部で内壁耐火物と同一成
分の固相が発生しても遠心力により外周部に分離される
ため、中心部での皮張り現象が非常に起こり難くなる。The third invention of the present invention has been made based on this finding, and the specific gravity of the high basicity unsaturated flux 14 added first on the molten steel 2 in the circulation tank 5 is higher than the specific gravity.
Next, the specific gravity of the saturated flux 15 added near the refractory on the inner wall forming the circulation tank 5 is increased. By increasing the specific gravity of the saturated flux 15 added in the vicinity of the inner wall refractory as compared with the unsaturated flux 14 having a high basicity, a solid phase having the same component as the inner wall refractory forming the circulation tank 5 is formed in the outer peripheral portion. Even if a solid phase having the same component as that of the inner wall refractory is generated at the central portion, it is separated to the outer peripheral portion by centrifugal force, so that skinning at the central portion is very unlikely to occur.
【００２０】この一例として、たとえば回流槽５を形成
する内壁耐火物の耐火材主成分をMgO とし、このMgO を
飽和溶解度未満に含有する未飽和フラックス（高塩基度
フラックス）がCaO 、SiO2、Al2O3 を主成分とする場合
が挙げられる。MgO の固体の比重は3.5 程度であり、一
般に用いられるCaO 、SiO2、Al2O3 を主成分とした高塩
基度フラックスの比重は2.5 〜3.0 程度であるため、前
記第２発明の効果を十分に得ることが可能となる。As an example of this, for example, the refractory material main component of the inner wall refractory forming the circulation tank 5 is MgO, and the unsaturated flux (high basicity flux) containing this MgO below the saturation solubility is CaO, SiO 2 , There is a case where Al 2 O 3 is used as a main component. The specific gravity of the solid MgO is about 3.5, and the specific gravity of the high basicity flux mainly composed of CaO, SiO 2 and Al 2 O 3 is about 2.5 to 3.0. It is possible to obtain enough.
【００２１】本発明では、第４発明のように図１におい
て取鍋１に保持した溶鋼２をロングノズル３を介して回
流槽５内の溶鋼２の中心部に供給するのが、未飽和フラ
ックス14と飽和フラックス15の攪拌による混合を防止す
るのに好適である。In the present invention, as in the fourth invention, the molten steel 2 held in the ladle 1 in FIG. 1 is supplied to the center of the molten steel 2 in the circulation tank 5 through the long nozzle 3 by using the unsaturated flux. This is suitable for preventing mixing of the saturated flux 15 with 14 by stirring.
【００２２】[0022]
【実施例】図３に示すように回転磁場発生装置６の電磁
力によって溶鋼２に水平方向の回転流を生成させる円筒
型の回流槽５と、該回流槽５に連通され溶鋼２中の非金
属介在物を浮上分離させる浮上槽９とを備えるタンディ
ッシュ４において、回流槽５の内壁耐火物としてマグネ
シアコーティング材（MgO ：90％、SiO2：９％、Al
2O3 ：１％）を25mm厚で均一にコーティングし、鋳造開
始前の全酸素濃度を25〜30ppm に調整した16％ステンレ
ス鋼の連続鋳造を行った。タンディッシュ４が備えた回
流槽５に添加するフラックスは、表１に示したＡ〜Ｄに
示す４種類を用い、３つの水準で連続鋳造を行った。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
Cylinder that generates horizontal rotating flow in molten steel 2 by force
Mold circulation tank 5 and non-metal in molten steel 2
With a floating tank 9 for floating and separating metal inclusions
In the brush 4, the inner wall of the circulation tank 5
Shear coating material (MgO: 90%, SiOTwo: 9%, Al
TwoOThree: 1%) uniformly coated with 25mm thickness
16% stainless steel with total oxygen concentration adjusted to 25-30ppm before starting
Continuous casting of stainless steel was performed. Times tundish 4 has
Fluxes to be added to the flow tank 5 are shown in A to D shown in Table 1.
Using the four types shown, continuous casting was performed at three levels.
【００２３】[0023]
【表１】 [Table 1]
【００２４】水準１では、従来から一般的に使用されて
いるフラックスＡのみを50kg用い、水準２ではフラック
スＢを50kg、水準３ではフラックスＣを35kgそれぞれ用
いてロングノズル３の近傍に添加し、その後、フラック
スＤを15kg用い、回流槽５の湯面外周部へ均一に添加し
た。その際、回流槽５の中心部に初めに添加する未飽和
フラックス14の成分を表１に示したＡ〜Ｃの３水準とし
た。なお、表１においてフラックスＤは回流槽５の周辺
部に添加する飽和フラックス15の成分を示している。図
４に各水準で行った鋳造時間と使用後のタンディッシュ
４の回流槽５内に添加したフラックスラインにおける内
壁耐火物の最大溶損深さの測定結果を示した。At the level 1, 50 kg of only the flux A generally used conventionally is used, at the level 2, 50 kg of the flux B is used, and at the level 3, 35 kg of the flux C is added to the vicinity of the long nozzle 3. Thereafter, 15 kg of the flux D was uniformly added to the outer periphery of the molten metal surface of the circulation tank 5. At this time, the components of the unsaturated flux 14 initially added to the central portion of the circulation tank 5 were set to three levels of A to C shown in Table 1. In Table 1, the flux D indicates a component of the saturated flux 15 added to the periphery of the circulation tank 5. FIG. 4 shows the results of measuring the casting time at each level and the maximum erosion depth of the refractory on the inner wall in the flux line added to the circulation tank 5 of the used tundish 4 after use.
【００２５】図４に示すように従来法である水準１と比
較して、本発明法である水準２、３で内壁耐火物の溶損
が大幅に低減していることが分かる。特に、水準３では
長時間の鋳造に対してもその効果は顕著であり、大きな
効果が確認された。図５に各水準でタンディッシュ４の
排出口である浸漬ノズル11の直上から採取した溶鋼２の
全酸素濃度の平均値を示した。本発明によれば内壁耐火
物の溶損が減少したことにより、全酸素濃度も低下した
ことが分かる。また、各水準の鋳造での皮張り発生率を
図６に示す。図６に示すように水準２に対し、水準３で
は皮張り発生率がさらに低下したことが分かる。As shown in FIG. 4, it can be seen that the erosion loss of the refractory on the inner wall is significantly reduced at the levels 2 and 3 according to the present invention, as compared with the level 1 according to the conventional method. In particular, at level 3, the effect was remarkable even for long-time casting, and a great effect was confirmed. FIG. 5 shows the average value of the total oxygen concentration of the molten steel 2 collected from immediately above the immersion nozzle 11 which is the outlet of the tundish 4 at each level. It can be seen that according to the present invention, the total oxygen concentration also decreased due to the decrease in the erosion of the inner wall refractory. FIG. 6 shows the rate of skinning at each level of casting. As shown in FIG. 6, it can be seen that the skinning occurrence rate was further reduced at level 3 compared to level 2.
【００２６】なお、本実施例ではフラックスＤにMg0 含
有量が37％のフラックスを用いたが、特に、このように
MgO を予め混合したフラックスを用いる場合に限る必要
はなく、MgO クリンカー（MgO ：95％、CaO ：１％、Si
O2：0.3 ％）等を、回流槽内に逐次に添加しても同様の
効果が得られる。In this embodiment, a flux D having a Mg0 content of 37% was used as the flux D.
It is not necessary to use only a flux in which MgO is mixed in advance, and MgO clinker (MgO: 95%, CaO: 1%, SiO
O 2 : 0.3%) and the like can be added sequentially to the circulation tank to obtain the same effect.
【００２７】[0027]
【発明の効果】以上説明したように本発明によれば、タ
ンディッシュが備えた回流槽内の溶融金属を電磁力によ
って水平回転流を生成させつつ、溶融金属上に回流槽を
形成する内壁耐火物の耐火材主成分と同一の成分を飽和
溶解度以上に含有する組成とした非金属介在物吸収能を
有するフラックスを添加し、該フラックス添加層により
回流槽を形成する内壁耐火物が溶損するのを防止する。
これにより回流槽内において溶融金属の再酸化を防止す
ると共に非金属介在物吸収能を有する高塩基度のフラッ
クスを使用することが可能なり、連続鋳造による経済的
な高清浄鋼の製造が達成される。As described above, according to the present invention, the refractory metal in the circulation tank provided in the tundish is generated by the electromagnetic force to generate a horizontal rotating flow, and the inner wall refractory for forming the circulation tank on the molten metal is formed. A flux having a non-metallic inclusion absorption capacity having a composition containing the same component as the main component of the refractory material at a saturation solubility or higher is added, and the refractory material on the inner wall forming the circulation tank is melted by the flux-added layer. To prevent
This makes it possible to prevent the reoxidation of the molten metal in the circulation tank and to use a high basicity flux having the ability to absorb nonmetallic inclusions, thereby achieving economical production of high-purity steel by continuous casting. You.
【図１】本発明の第１発明の連続鋳造装置を示す縦断面
図である。FIG. 1 is a longitudinal sectional view showing a continuous casting apparatus according to a first invention of the present invention.
【図２】本発明の第１発明の連続鋳造装置を示す平面図
である。FIG. 2 is a plan view showing a continuous casting apparatus according to the first invention of the present invention.
【図３】本発明の第２発明の連続鋳造装置を示す縦断面
図である。FIG. 3 is a longitudinal sectional view showing a continuous casting apparatus according to a second invention of the present invention.
【図４】連続鋳造の鋳造時間と回流槽を形成する内壁耐
火物の耐火物溶解量の関係をフラックス水準別に示すグ
ラフである。FIG. 4 is a graph showing, for each flux level, the relationship between the casting time of continuous casting and the amount of refractory dissolved in the inner wall refractories forming the circulation tank.
【図５】タンディッシュ排出口における溶鋼中の全酸素
量をフラックスの水準別に示す棒グラフである。FIG. 5 is a bar graph showing the total oxygen content in molten steel at a tundish discharge outlet for each flux level.
【図６】回流槽内のフラックスの皮張り発生率をフラッ
クスの水準別に示す棒グラフである。FIG. 6 is a bar graph showing the rate of occurrence of skinning of the flux in the circulation tank for each flux level.
【図７】従来の連続鋳造装置を示す縦断面図である。FIG. 7 is a longitudinal sectional view showing a conventional continuous casting apparatus.
【図８】従来の連続鋳造装置を示す平面図である。FIG. 8 is a plan view showing a conventional continuous casting apparatus.
【図９】従来の連続鋳造装置における回流槽の内壁耐火
物の溶損状況を示す説明図である。FIG. 9 is an explanatory view showing the state of erosion of the refractory on the inner wall of the circulation tank in the conventional continuous casting apparatus.
１ 取鍋 ２ 溶鋼 ３ ロングノズル ４ タンディッシュ ５ 回流槽 ６ 回転磁場発生装置 ７ 高塩基度スラグ ８ 連通口 ９ 浮上槽 10 高塩基度フラックス 11 浸漬ノズル 12 水冷鋳型 13 鋳片 14 未飽和フラックス 15 飽和フラックス 16 溶損部 17 浮上スラグ Reference Signs List 1 Ladle 2 Molten steel 3 Long nozzle 4 Tundish 5 Flow tank 6 Rotating magnetic field generator 7 High basicity slag 8 Communication port 9 Floating tank 10 High basicity flux 11 Immersion nozzle 12 Water-cooled mold 13 Cast slab 14 Unsaturated flux 15 Saturation Flux 16 Melted part 17 Floating slag
Claims (4)
生成させて非金属介在物を粗大化させる円筒型の回流槽
と該回流槽に連通され溶融金属中の非金属介在物を浮上
分離させる浮上槽とを備えるタンディッシュに取鍋に保
持した溶融金属を連続的に供給して非金属介在物を浮上
分離し、次いでこの非金属介在物の低減された溶融金属
を上下開放の水冷鋳型に連続的に注湯して鋳片とする溶
融金属の連続鋳造方法において、前記回流槽内の溶融金
属上に形成する非金属介在物の吸収能を有するフラック
ス層の少なくとも該回流槽を形成する内壁耐火物と接す
る部分の組成を耐火材主成分と同一の成分を飽和溶解度
以上に含有する組成としたことを特徴とする溶融金属の
連続鋳造方法。1. A cylindrical circulation tank for generating a horizontal rotating flow in a molten metal by electromagnetic force to coarsen nonmetallic inclusions, and is communicated with the circulation tank to float and separate nonmetallic inclusions in the molten metal. A molten metal held in a ladle is continuously supplied to a tundish having a floating tank and a nonmetallic inclusion is floated and separated, and then the molten metal reduced in the nonmetallic inclusion is poured into a vertically open water-cooled mold. In the method for continuously casting molten metal into a slab by continuously pouring, at least the inner wall of a flux layer having absorptive capacity for nonmetallic inclusions formed on the molten metal in the circulation tank is formed. A continuous casting method for molten metal, wherein a composition of a portion in contact with a refractory is a composition containing the same component as a main component of a refractory material at a saturation solubility or higher.
生成させて非金属介在物を粗大化させる円筒型の回流槽
と該回流槽に連通され溶融金属中の非金属介在物を浮上
分離させる浮上槽とを備えるタンディッシュに取鍋に保
持した溶融金属を連続的に供給して非金属介在物を浮上
分離し、次いでこの非金属介在物の低減された溶融金属
を上下開放の水冷鋳型に連続的に注湯して鋳片とする溶
融金属の連続鋳造方法において、回流槽内の溶融金属上
に、該回流槽を形成する内壁耐火物の耐火材主成分と同
一の成分を飽和溶解度未満に含有する組成とした非金属
介在物吸収能を有するフラックスを初めに添加し、次に
前記回流槽を形成する内壁耐火物の近傍に、該内壁耐火
物の耐火材主成分と同一の成分を飽和溶解度以上に含有
する組成とした非金属介在物吸収能を有するフラックス
を添加することを特徴とする溶融金属の連続鋳造方法。2. A cylindrical circulation tank for generating a horizontal rotating flow in a molten metal by electromagnetic force to coarsen nonmetallic inclusions, and is communicated with the circulation tank to float and separate nonmetallic inclusions in the molten metal. A molten metal held in a ladle is continuously supplied to a tundish having a floating tank and a nonmetallic inclusion is floated and separated, and then the molten metal reduced in the nonmetallic inclusion is poured into a vertically open water-cooled mold. In the continuous casting method of molten metal that is continuously poured into a slab, the same component as the main component of the refractory material of the inner wall refractory forming the circulation tank is less than the saturation solubility on the molten metal in the circulation tank. First, a flux having a non-metallic inclusion absorbing ability having a composition contained therein is added, and then, in the vicinity of the inner wall refractory forming the circulation tank, the same component as the main component of the refractory material of the inner wall refractory is added. Non-gold with composition containing more than saturated solubility A method for continuously casting molten metal, comprising adding a flux having a function of absorbing metal inclusions.
フラックスの比重よりも次に回流槽の内壁耐火物近傍に
添加するフラックスの比重を大とすることを特徴とする
請求項２記載の溶融金属の連続鋳造方法。3. The method according to claim 2, wherein the specific gravity of the flux added next to the refractory on the inner wall of the circulation tank is larger than the specific gravity of the flux added first on the molten metal in the circulation tank. Continuous casting method of molten metal.
を介して回流槽の中心部に供給することを特徴とする請
求項１、２または３記載の溶融金属の連続鋳造方法。4. The method for continuously casting molten metal according to claim 1, wherein the molten metal held in a ladle is supplied to a central portion of a circulation tank via a long nozzle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9000198A JPH10193050A (en) | 1997-01-06 | 1997-01-06 | Method for continuously casting molten metal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9000198A JPH10193050A (en) | 1997-01-06 | 1997-01-06 | Method for continuously casting molten metal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH10193050A true JPH10193050A (en) | 1998-07-28 |
Family
ID=11467297
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9000198A Pending JPH10193050A (en) | 1997-01-06 | 1997-01-06 | Method for continuously casting molten metal |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102688992A (en) * | 2012-06-13 | 2012-09-26 | 鞍钢股份有限公司 | Method for synthetic slag washing of tundish |
| CN103894571A (en) * | 2014-03-28 | 2014-07-02 | 上海大学 | Method of purifying molten steel in tundish by gas vortex and molten steel purification device |
| CN103962540A (en) * | 2014-05-13 | 2014-08-06 | 南京钢铁股份有限公司 | Continuous casting tundish, crystallizer molten steel flow control device and using method |
| JP2019214057A (en) * | 2018-06-11 | 2019-12-19 | 日本製鉄株式会社 | Continuous casting method |
| JP2021013944A (en) * | 2019-07-11 | 2021-02-12 | 日本製鉄株式会社 | Continuous casting process |
-
1997
- 1997-01-06 JP JP9000198A patent/JPH10193050A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102688992A (en) * | 2012-06-13 | 2012-09-26 | 鞍钢股份有限公司 | Method for synthetic slag washing of tundish |
| CN103894571A (en) * | 2014-03-28 | 2014-07-02 | 上海大学 | Method of purifying molten steel in tundish by gas vortex and molten steel purification device |
| CN103962540A (en) * | 2014-05-13 | 2014-08-06 | 南京钢铁股份有限公司 | Continuous casting tundish, crystallizer molten steel flow control device and using method |
| JP2019214057A (en) * | 2018-06-11 | 2019-12-19 | 日本製鉄株式会社 | Continuous casting method |
| JP2021013944A (en) * | 2019-07-11 | 2021-02-12 | 日本製鉄株式会社 | Continuous casting process |
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