JP3563786B2 - Method and apparatus for opening a molten metal tapping nozzle attached to a molten metal container - Google Patents

Description

【００２７】
【発明の効果】
以上に詳述したように、本発明によれば、取鍋や炉底出銑機構を有する電気炉などの溶融金属容器に付設される溶融金属出湯用ノズル、たとえばスライディングノズルの開孔は、出湯前および／または出湯時に、容器外から付与されるエネルギーによって、ノズル近傍に貯留している溶湯を流動させる方法で行われる。
【００２８】
より具体的で好適な方法として、容器外からノズル近傍に貯留している溶湯中へガスを噴出させるか、または同じくノズル近傍に貯留している溶湯を電磁誘導して、同溶湯を流動させる方法で行われる。これによって、２０００℃近くにもなる高温溶湯の容器内滞留時間が長い場合でも、またこのような滞留時間の長い精錬取鍋でも、ノズル孔に金属凝固層が形成されるのを妨げられ、一方ノズル開孔時に金属凝固層が厚くならないように、また軟化することができるため、ノズルの自然開孔率が殆ど支障なく大幅に向上するので、作業性、能率および生産性が大幅に向上する。また、危険な酸素ランスによる強制的な酸素開孔作業回数が大幅に低減されるので、時間や組成成分や温度などの実作業管理上のバラツキもなくなり、作業性や安全性ならびに品質が大幅に向上する。
【００２９】
また、本発明によれば、溶融金属容器の底に付設されるノズルに粒状充填材を充填し、そのノズル近傍に貯留している溶湯に対して不活性ガスを底から噴出させるか、または同溶湯を電磁誘導し流動させて、粒状充填材表層の凝固層および焼結層を軟化させ、ノズル開孔が行われる。これによって溶湯の容器内滞留時間が長い場合でもノズルの自然開孔率が大幅に向上するので、能率および生産性が大幅に向上する。また、危険な酸素ランスによる酸素開孔回数が大幅に低減されるので、安全性並びに品質が大幅に向上する。
【００３０】
また本発明によれば、溶融金属容器のノズル開孔装置は、ノズルと、そのノズル近傍でガスを噴出させるたとえばポーラスプラグとを含む。これによって凝固層の薄層化並びに粒状充填材表層の凝固層および焼結層の軟化を図ることができるので、ノズルの自然開孔率が大幅に向上する。このため、能率、生産性、安全性および品質等が大幅に向上する。
【００３１】
また本発明によれば、溶融金属容器に設けられるノズルはスライディングノズルである。これによって溶融金属の流量調整を迅速かつ正確に行うことができるので、円滑な出湯作業を実施することができる。
【図面の簡単な説明】
【図１】本発明の一実施例である取鍋底部に設けられている溶融金属出湯用ノズルの開孔装置の簡略化された構成とノズル開孔方法とを示す断面図である。
【図２】図１に示すノズル開孔装置を構成するガス吹込用ノズルの簡略化された構成を示す断面図である。
【図３】図２における切断面線ＩＩＩ−ＩＩＩから見た断面図である。
【図４】本発明の他の実施例である溶融金属出湯用ノズルの開孔方法を示す説明図である。
【図５】本発明のさらに他の実施例である溶融金属出湯用ノズルの開孔方法を示す説明図である。
【図６】スライディングノズルの簡略化された構成を示す断面図である。
【符号の説明】
１，１４ 上部ノズル
２，１５ 上部プレート
３，１６ 下部プレート
４，１７ 下部ノズル
５，２５ 粒状充填材
６，２６ 焼結層
７，２７ 凝固層
１０ 取鍋（精錬取鍋）
１２ スライディングノズル
１３ ガス吹込用ノズル
１８ マスれんが
２０ 溶融金属（溶湯）
２１ ガス吹込用ノズルの取付れんが
２４ ノズル孔
２５ ポーラス質耐火物体
２６ 不定形耐火物体
２７ 連結管
２８ ガス分配器
２９ ガス供給管
４０ 電磁誘導装置[0001]
[Industrial applications]
The present invention provides a molten metal tapping nozzle attached to various molten metal containers used in each step of melting and melting, smelting and refining of metals including ores and alloys, when opening (opening) The present invention relates to a method and an apparatus for opening a nozzle for spouting molten metal (metal melt) naturally.
[0002]
[Prior art]
2. Description of the Related Art Generally, in each process of melting and melting or smelting and refining metals such as ores, alloys, and metal scraps, a molten metal container such as a smelting furnace, an electric furnace, a ladle, and a smelting ladle is used.
[0003]
In any case, mainly molten metal (hereinafter, sometimes referred to as molten metal or simply molten metal) generated and stored by charging a raw material or pouring a molten metal into such a molten metal container is discharged or discharged outside the container in any case. Outflow (hereinafter simply referred to as hot water). To this end, a tapping device for tapping molten metal or the like or a flow control tapping device such as a sliding nozzle device or a stopper nozzle device is attached to the bottom or side wall of the container.
[0004]
Hereinafter, with respect to such various containers and devices, a ladle for storing molten metal and transporting it to the next process, or a refining process used not only for transporting it to the next process but also for refining the stored molten metal. This will be described using examples of pots and sliding nozzle devices attached to these pots.
[0005]
The sliding nozzle device attached to such a ladle includes an upper nozzle 1, an upper plate 2, a lower plate 3, a lower nozzle 4 and the like as shown in FIG. The flow rate of molten metal (hereinafter sometimes referred to as molten metal) in the ladle is adjusted or stopped. When the molten metal is poured into a ladle equipped with such a sliding nozzle device, the molten metal that has entered the nozzle holes of the upper nozzle 1 and the upper plate 2 is cooled and solidified even if the container itself is preheated. Therefore, even if the lower plate 3 is slid and the nozzle hole is opened, the molten metal does not flow out of the ladle through the sliding nozzle device, so-called a non-open state of the sliding nozzle device occurs. For this reason, conventionally, a method has been adopted in which the nozzle holes of the upper nozzle 1 and the upper plate 2 are filled with a particulate filler 5 to seal the nozzle holes, thereby preventing intrusion of molten metal.
[0006]
Examples of the granular filler 5 include silica sand, chromite ore particles, carbon particles, and alkali oxides (K ₂ O, Na ₂ O) Grains and the like are used. However, in this granular filler 5, (1) the upper part of the granular filler 5 is caused to flow by the initial molten metal flow when the molten metal is poured into the ladle from the outside, and (2) the granular filler 5 is heated by the heat of the molten metal. Sinters in the nozzle hole to form a sintered layer. (3) There is a problem that molten metal intrudes between particles of the particulate filler 5 to form an infiltrated solidified layer. In particular, when performing secondary refining such as vacuum degassing, which has become very popular recently, it is necessary to increase the temperature of the molten metal, lengthen the refining time, and match the secondary refining process with the continuous casting process after the secondary refining. Since the prolonged waiting time often occurs inevitably, the residence time until the molten metal is discharged from the refining ladle becomes extremely long. Therefore, the formation of the sintered layer or the interstitial solidified layer is remarkably promoted. In this case, even if the sliding nozzle is opened to discharge the molten metal in the smelting ladle, the sintered layer or the penetrating solidified layer is not spontaneously broken by the static pressure of the molten metal, and is naturally opened by the static pressure of the molten metal. It is difficult to make a so-called natural hole. In that case, an oxygen lance must be inserted from the lower nozzle 4 and oxygen gas must be blown to melt the sintered layer or the interstitial solidified layer to forcibly open the nozzle hole, so-called oxygen opening. . Oxygen opening is not only a dangerous operation, but also lowers the yield due to the release (discarding) of expensive molten metal, makes it impossible to secure the planned amount of molten metal, delays molten metal discharge, and lowers the temperature of molten metal due to this. ) Has a great adverse effect on the processing work of the next step, so that safety, quality and economic losses are very large.
[0007]
[Problems to be solved by the invention]
In order to address such a problem, many prior arts have been disclosed. In the prior art disclosed in Japanese Patent Publication No. 46-21830, in order to prevent solidification of the molten metal in the nozzle hole, when the lower plate 3 is in a closed state, an inert gas is supplied from pores provided in the lower plate 3. This is a method that does not use a granular filler supplied into the nozzle hole. This method is an effective method when the pouring of the molten metal is stopped on the way and re-pouring, but when performing secondary refining such as vacuum degassing for which the molten metal residence time is long, This is not applicable because the molten metal in the nozzle is cooled by the inert gas and may be solidified.
[0008]
In the prior art disclosed in Japanese Patent Application Laid-Open No. 55-10374, a granular filler containing an organic binder is provided at an upper portion in contact with a molten metal in a nozzle hole of a sliding nozzle, and a normal granular filler is provided at a lower portion. It is a method of filling. This method has an effect on the loss and floating of particulate filler due to the flow of molten metal, but it is effective when secondary refining is performed where the temperature of the molten metal is high and the residence time in the ladle is long. Will not be recognized.
[0009]
In the prior art disclosed in Japanese Patent Application Laid-Open No. 52-147523, the upper layer in contact with the molten metal in the nozzle hole of the sliding nozzle is filled with a refractory material powder that produces a highly viscous glass to prevent the intrusion of the molten metal. Then, the lower layer is filled with a refractory material powder mixed with carbon to prevent sintering.
[0010]
In the prior art disclosed in Japanese Patent Application Laid-Open No. 55-94776, the lower layer is filled with a coarse granular filler in the nozzle hole of the sliding nozzle to prevent sintering, and the surface is sintered. This is a method for preventing the intrusion of molten metal by coating with an amorphous refractory that easily forms a layer.
[0011]
The prior arts disclosed in JP-A-52-147523 and JP-A-55-94776 have been developed to solve the problems of the prior art. According to the survey, no sufficient effect is obtained. According to the investigation by the present inventors, as shown in FIG. 6, formation of a solidified layer 7 in addition to the conventionally known sintered layer 6 at the interface with the molten metal is recognized in the granular filler 5 of the sliding nozzle. The solidified layer 7 is easily formed when the residence time of the molten metal in the ladle is long, and the solidified metal is formed on the sintered layer 6 in a state where the solidified metal is entangled with the sintered layer 6. Since the hot strength of the solidified layer 7 is higher than that of the sintered layer 6, the formation of the solidified layer 7 significantly reduces the natural opening ratio, which indicates the success rate of natural opening. Further, since the hot strength of the solidified layer 7 also depends on the molten metal component, for example, titanium and niobium-added stainless steel having high high-temperature strength and excellent toughness have a low natural porosity. As described above, each of the prior arts has a problem. Particularly, when the residence time of the molten metal in the refining ladle is long, the natural opening ratio of the sliding nozzle remains at a low level.
[0012]
An object of the present invention is to solve the above-mentioned problems of the prior art, and at the time of opening a molten metal tapping nozzle provided for a molten metal container, even if the molten metal, that is, the molten metal, stays in the container for a long time, It is an object of the present invention to provide a method and an apparatus for opening a nozzle for molten metal tapping, which can easily and spontaneously open the tap without causing difficulty or difficulty in opening the tap.
[0013]
[Means for Solving the Problems]
The present invention, when opening the openable and closable molten metal tapping nozzle attached to the bottom or side wall of the molten metal container, when tapping the molten metal stored in this container out of the container,
Before and / or at the time of tapping, the molten metal near the nozzle is caused to flow by energy applied from outside the container so as to prevent a solidified layer from being formed in the nozzle. This is a method for opening a molten metal tapping nozzle.
Further, the present invention provides, as the energy applied from outside the container, a method in which a gas is ejected from outside the container into the molten metal stored in the vicinity of the molten metal tapping nozzle or the molten metal stored in the vicinity of the nozzle as well. The molten metal stored near the nozzle is caused to flow by electromagnetic induction.
Further, the present invention also provides a method for filling a filler in a nozzle hole of a freely opening and closing molten metal tapping nozzle provided at the bottom of a molten metal container, and then filling the molten metal injected and stored in the container with the nozzle. When opening the bath and tapping out of the container,
Before and / or at the time of tapping, an inert gas, a nitrogen gas, or a mixed gas thereof is jetted from the bottom outside the container into the molten metal stored near the molten metal tapping nozzle.
Further, the present invention is characterized in that the molten metal container is a ladle for storing the molten metal or a refining ladle for storing the molten metal and used for refining.
Further, the invention is characterized in that the molten metal tapping nozzle is a sliding nozzle.
Further, the present invention is an apparatus for opening a freely openable and openable molten metal tapping nozzle attached to the bottom or side wall of a molten metal container, and tapping the molten metal stored in this container out of the container.
The container itself may be provided with a gas injection nozzle for ejecting gas in the vicinity of the molten metal tapping nozzle, or may be provided with an electromagnetic induction device for electromagnetically inducing molten metal stored near the molten metal tapping nozzle outside the container. The molten metal stored near the nozzle is flowed so as to prevent a solidified layer from being formed in the nozzle before and / or at the time of tapping. This is a hole opening device for a molten metal tapping nozzle.
[0014]
[Action]
According to the present invention, the openable and closable molten metal tapping nozzle attached to the bottom or side wall of the molten metal container is opened (opened) and stored in this container, for example, at about 2000 ° C. When a metal (a molten metal or simply a molten metal) is poured out of the container, the energy applied from outside the container before and / or during the tapping prevents the solidified layer from being formed in the nozzle in the vicinity of the nozzle. This is performed by a method of flowing the stored molten metal. Rather than directly vibrating the container itself or shaking the container itself by the physical stirring energy or electric energy applied from outside the container, the container exists near the nozzle (around the nozzle) and is almost stationary In this method, the melt is stirred or fluidized, and basically, the melt is fluidized. Thereby, even if the molten metal stays in the container for a long time, the formation of the solidified layer is hindered. In particular, the thickness of the solidified layer does not increase, and a strong solidified layer is not formed. When the tapping nozzles are opened, they are easily and spontaneously destroyed by the static pressure of the molten metal in the container, so that the nozzles are easily opened spontaneously, and the spontaneous opening ratio of the nozzles is greatly improved.
[0015]
According to the present invention, before and / or during tapping, energy is applied from outside the container in order to flow the molten metal stored near the molten metal tapping nozzle. In this container, a high-temperature molten metal having a temperature of about 2000 ° C. is usually controlled within a predetermined temperature range, and since it is not desired to lower the temperature outside this temperature range, for example, an impeller or a gas injection lance is inserted into the high-temperature molten metal. It is very difficult to directly immerse and operate such a stirring device (means).
[0016]
Therefore, it is necessary to apply energy from outside the container without directly immersing and operating the stirring / flowing device (means) in such a high-temperature molten metal. For this purpose, a gas supplied from outside the container is jetted into the molten metal stored in the vicinity of the nozzle, or electric energy is applied from outside the container to electromagnetically induce the molten metal to flow the molten metal. This is preferable without causing various problems.
[0017]
Further, according to the present invention, after filling the filler into the nozzle hole of the openable and closable molten metal tapping nozzle provided at the bottom of the container, the extremely high-temperature molten metal injected and stored in the container is provided. In order to discharge the (molten metal) out of the container, at the time of opening the nozzle, before and / or during the tapping, an inert gas, a nitrogen gas, or a mixture thereof is introduced into the molten metal stored near the nozzle from the bottom of the container. The method is performed by ejecting gas and causing the molten metal to flow out. This prevents the solidified layer and the sintered layer from growing thickly and firmly even if the very high-temperature molten metal stays in the container for a long time, and the temperature and softening of each layer are reduced. Since it can be realized, it can be easily and spontaneously broken by the static pressure of the molten metal, and the nozzle can be spontaneously opened and the hot water can be discharged without any particular trouble.
[0018]
【Example】
FIG. 1 is a cross-sectional view showing a simplified configuration of a hole opening device for a molten metal tapping nozzle provided at the bottom of a ladle according to one embodiment of the present invention, and a method for opening the nozzle, FIG. 2 is a cross-sectional view showing a simplified configuration of a gas blowing nozzle included in the nozzle opening device shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. .
[0019]
As shown in FIG. 1, a nozzle opening device 11 provided at the bottom of a ladle 10, which is one of the molten metal containers, includes a sliding nozzle 12 and a gas injection nozzle 13 provided near the nozzle. It is comprised including. The sliding nozzle 12 includes an upper nozzle 14 and an upper plate 15 fitted to the lower part thereof, a lower plate 16 slidable horizontally with respect to the upper plate 15, and a lower part fitted to a lower part of the lower plate 16. The nozzle 17 is included. The upper nozzle 14 is fitted to a mass brick 18 provided at the bottom of the ladle 10, and the upper plate 15 is fixed to an iron skin 19 forming the outermost layer of the ladle 10, not shown. It is fixed by a jig. The upper nozzle 14 and the upper plate 15 have nozzle holes of the same diameter, and both nozzle holes have a common vertical axis. The same is true for the lower plate 16 and the nozzle holes of the lower nozzle 17. The lower plate 16 is slid in the horizontal direction by a hydraulic cylinder (not shown). FIG. 1 shows a state in which a nozzle hole 24 formed by the upper nozzle 14 and the upper plate 15 is closed on the upper surface of the lower plate 16. If the axes of the nozzle holes are aligned by sliding the lower plate 16, the sliding nozzle 12 is opened (opened), and the molten metal 20 in the ladle 10 can be discharged (discharged).
[0020]
As shown in FIG. 2, a porous plug, which is a kind of gas injection nozzle 13, includes a porous refractory body 25, a gas supply pipe 29, a gas distributor 28, a connection pipe 27, and an irregular refractory body 26. It is comprised including. The porous refractory body 25 is a tapered cylindrical porous body, and the diameter of the lower end is larger than the diameter of the upper end. The gas distributor 28 is a disc-shaped container made of steel. A gas supply pipe 29 is provided at a lower end thereof, and a plurality of connecting pipes 27 are equally provided at an upper end thereof as shown in FIG. Have been. The gas distributor 28 uniformly supplies gas to the porous refractory body 25 via the connection pipe 27. The porous refractory 25, the connecting pipe 27, and the gas distributor 28 are embedded and fixed inside the irregular refractory 26 except for the upper end of the porous refractory 25. In the center of the lower end of the porous refractory body 25, a recess 30 is provided, which forms an internal space inside the irregular refractory body 26. The free end of the connecting pipe 27 is provided so as to protrude into this internal space. The shape of the refractory body 26 is a tapered cylindrical body, and the diameter of the lower end is larger than the diameter of the upper end. These irregular refractory bodies 26, porous refractory bodies 25 and gas distributors 28 have a common vertical axis. As shown in FIG. 1, the gas injection nozzle 13, for example, a porous plug, is fitted to a porous plug mounting brick 21 disposed at the bottom of the ladle 10.
[0021]
In the present embodiment, the opening of the opening / closing nozzle for the molten metal that can be opened and closed is performed as follows. After closing the sliding nozzle 12, the molten metal 20 is poured into the ladle 10. After pouring the molten metal, the ladle (refining ladle) 10 in which the molten metal 20 is stored is sent to the next step, so it is simply transported to each device or facility at a predetermined position and discharged, or the refining is performed in secondary refining or the like. The pot 10 is placed in a refining apparatus and subjected to a predetermined ladle refining process, then transported to, for example, a continuous casting facility, and discharged for continuous casting. In any case, before and / or at the time of tapping, an inert gas, a nitrogen gas, or a mixed gas thereof, for example, an argon gas, is supplied from the gas injection nozzle 13 provided near the sliding nozzle 12 to the molten metal 20. It is blown in. When an inexpensive nitrogen gas or a mixed gas of a nitrogen gas and an inert gas is used as the gas to be blown, even if the molten metal 20 is nitrided, it is limited to an allowable range in terms of the composition. Have. For example, argon gas blown into the melt 20 is blown into the melt 20 as fine argon gas bubbles through the gas supply pipe 29, the gas distributor 28, the connecting pipe 27, and the porous refractory body 25. Since the molten metal 20 is locally stirred by the blown argon gas bubbles, a flow of the molten metal in the direction of the arrow 22 occurs in the molten metal 20. The flow of the molten metal 20 spreads into the nozzle hole 24, and the high-temperature molten metal 20 in the ladle 10 flows into the nozzle hole 24, so that the solidified layer formed in the nozzle hole 24 is formed. 23 is re-melted, and the thickness of the solidified layer 23 decreases to a value determined by the calorific value balance. Therefore, the thickness of the solidified layer 23 is not increased during the blowing of the argon gas. Therefore, if the sliding nozzle 12 is opened (opened), the solidified layer 23 is easily broken by the static pressure of the molten metal 20, and the sliding nozzle 12 is opened by so-called natural opening. The method disclosed in Japanese Patent Publication No. 46-21830 discloses a method in which an inert gas is blown into the nozzle holes 24 through fine holes provided in the lower plate 16 of the sliding nozzle 12 and a method according to the present embodiment. If used together, the flow in the nozzle hole 24 becomes intense, so that the thickness of the solidified layer 23 can be further reduced.
[0022]
FIG. 4 is an explanatory view showing a method of opening a molten metal tapping nozzle according to another embodiment of the present invention. Parts corresponding to those in FIG. 1 are denoted by the same reference numerals. In the present embodiment, the same nozzle opening device 11 as in FIG. 1 is used, and the nozzle opening is performed as follows. After the sliding nozzle 12 is closed, the granular filler 25 is filled in the nozzle hole 24 formed by the upper nozzle 14 and the upper plate 15, and the molten metal 20 is poured into the ladle 10. When the residence time of the molten metal 20 in the ladle 10 is long due to secondary refining or the like, a sintered layer 26 and a solidified layer 27 are formed in the particulate filler 25 at the interface with the molten metal. Since the solidified layer 27 is formed in a state in which the molten metal that has penetrated the sintered layer 26 is solidified and entangled with the sintered layer 26, the solidified layer 27 is a very strong layer and significantly impedes natural pores. When the molten metal 20 is normally discharged from the ladle 10, or when the sliding nozzle 12 is not opened even when the sliding nozzle 12 is opened, the gas injection nozzle 13 provided in the vicinity of the sliding nozzle 12 is not used. An active gas, a nitrogen gas, or a mixed gas thereof, for example, an argon gas, is blown into the molten metal 20. The injection of the argon gas stirs the molten metal 20, causing a flow of the molten metal 20 in the direction of the arrow 22 in the molten metal 20. Due to the flow of the molten metal 20, the flowing high-temperature molten metal 20 prevents the formation of the solidified layer 27 and the sintered layer 26, while increasing their temperature and greatly reducing their strength. These layers are destroyed by the pressure, and the molten metal 20 starts to flow (flow out) by a so-called natural opening in a short time. The particle size of the particulate filler 25 is preferably adjusted to 0.5 to 2.5 mm. The reason why the diameter is limited to 0.5 to 2.5 mm is that when the particle size exceeds 2.5 mm, the molten metal 20 penetrates deeply between the particles to form a deep infiltrated solidified layer, and the molten metal 20 also flows due to the flow of the molten metal 20. This is because it is difficult to perform spontaneous opening, while if it is less than 0.5 mm, the sintered layer 26 is formed to be extremely thick, and it is difficult to spontaneously open even by the flow of the molten metal 20. In this embodiment, the grain size of the particulate filler 25 is adjusted to the appropriate range to form the sintered layer 26 having an appropriate thickness, thereby preventing the formation of the deep (thick) interstitial solidified layer 27. Therefore, the natural pore rate can be greatly improved by the flow of the molten metal 20.
[0023]
FIG. 5 is an explanatory view showing a method for opening a molten metal tapping nozzle according to still another embodiment of the present invention. 1 and 4 are denoted by the same reference numerals.
[0024]
In this embodiment, the same nozzle opening device 11 as in FIGS. 1 and 4 is used, and the nozzle opening is performed in the same manner as described above with reference to FIG. Prior to tapping, before the tapping, the electromagnetic induction device 40 provided near the molten metal tapping nozzle 12 is energized by the iron shell 19 forming the outermost layer of the ladle 10, and the molten metal 20 near the nozzle 12 is electromagnetically induced. . Due to this electromagnetic induction, the molten metal 20 in the ladle 10 flows in the direction of the arrow 22 in the molten metal 20. Due to the flow of the molten metal 20, the high-temperature molten metal 20 flowing and supplied hinders the formation of the solidified layer 27 and the sintered layer 26, while increasing their temperature to greatly reduce their thickness and strength. Since the temperature is lowered, the molten metal 20 is easily and spontaneously broken by the static pressure, and the molten metal 20 starts to be discharged (discharged) by a so-called natural opening in a short time.
[0025]
Next, the excellent nozzle opening characteristics of this embodiment will be specifically described. The molten metal used in the present embodiment is a molten metal for producing stainless steel. As the steel type, SUS430, which is a typical ferritic stainless steel, has high temperature strength and high toughness. A low SUS444 (19Cr-2Mo-0.4Nb) was selected. Using a refining ladle 10 provided with a nozzle opening device 11 shown in FIG. 1 at the bottom thereof, filling a granular filler having an average particle size of 1.0 mm into the nozzle holes 24 of the sliding nozzle 12, and then into the refining ladle. A molten metal for melting stainless steel was injected. The refining ladle 10 that received the hot water was subjected to secondary refining in a vacuum degassing device, and then transferred to a continuous casting device. The component composition of the granular filler used in this example is SiO 2 ₂ 92 wt. %, Al ₂ O ₃ 4.0 wt. %, Alkali oxide (K ₂ O, Na ₂ O) 4.0 wt. %. In the continuous casting device, the sliding nozzle 12 was opened and the molten steel was poured into the tundish while adjusting the flow rate. The average residence time of the molten metal for producing stainless steel in the refining ladle was about 90 minutes. Table 1 shows the spontaneous porosity according to the conventional method for 20 charges for each steel type, and the spontaneous porosity when the method of the present invention is continuously applied to the charge that did not lead to spontaneous opening in the conventional method. Is shown. In the method of the present invention, argon gas is blown into stainless steel molten steel from a gas injection nozzle (porous plug) 13 provided near the sliding nozzle 12 for 15 seconds, and the molten steel stored near the nozzle 12 is stirred and fluidized. Was. From Table 1, it can be seen that the spontaneous porosity is generally low in the conventional method and particularly low in SUS444, but the spontaneous porosity is significantly improved to 100% by applying the method of the present invention.
[0026]
[Table 1]

[0027]
【The invention's effect】
As described in detail above, according to the present invention, the opening of a molten metal tapping nozzle, for example, a sliding nozzle attached to a molten metal container such as a ladle or an electric furnace having a bottom tapping mechanism, is provided with a tapping hole. This is performed by a method in which the molten metal stored in the vicinity of the nozzle is fluidized by energy applied from outside the container before and / or at the time of tapping.
[0028]
As a more specific and preferable method, a method in which a gas is ejected from the outside of the container into the molten metal stored in the vicinity of the nozzle, or the molten metal also stored in the vicinity of the nozzle is electromagnetically induced to flow the molten metal Done in This prevents the formation of a metal solidified layer in the nozzle hole even when the residence time of the high-temperature molten metal, which is close to 2000 ° C., in the container is long, and even in a smelting ladle having such a long residence time. Since the metal solidified layer does not become thicker and can be softened when the nozzle is opened, the natural opening rate of the nozzle is largely improved without any hindrance, so that the workability, efficiency and productivity are greatly improved. In addition, since the number of forced oxygen opening operations due to dangerous oxygen lances is greatly reduced, there is no variation in actual operation management such as time, composition, temperature, etc., and workability, safety and quality are greatly improved. improves.
[0029]
Further, according to the present invention, a granular material is filled in a nozzle provided at the bottom of a molten metal container, and an inert gas is ejected from the bottom to the molten metal stored near the nozzle, or The molten metal is caused to flow by electromagnetic induction to soften the solidified layer and the sintered layer on the surface of the granular filler, and the nozzle is opened. As a result, even when the residence time of the molten metal in the container is long, the spontaneous opening ratio of the nozzle is greatly improved, so that efficiency and productivity are greatly improved. Also, the number of oxygen holes caused by dangerous oxygen lances is greatly reduced, so that safety and quality are greatly improved.
[0030]
Further, according to the present invention, a nozzle opening device for a molten metal container includes a nozzle and, for example, a porous plug that ejects gas near the nozzle. This makes it possible to reduce the thickness of the solidified layer and soften the solidified layer and the sintered layer of the surface layer of the particulate filler, so that the spontaneous opening ratio of the nozzle is greatly improved. For this reason, efficiency, productivity, safety, quality, and the like are greatly improved.
[0031]
According to the invention, the nozzle provided in the molten metal container is a sliding nozzle. As a result, the flow rate of the molten metal can be adjusted quickly and accurately, so that a smooth tapping operation can be performed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a simplified configuration of a hole opening device for a molten metal tapping nozzle provided on a ladle bottom according to an embodiment of the present invention and a nozzle opening method.
FIG. 2 is a cross-sectional view showing a simplified configuration of a gas blowing nozzle included in the nozzle opening device shown in FIG.
FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2;
FIG. 4 is an explanatory view showing a method of opening a molten metal tapping nozzle according to another embodiment of the present invention.
FIG. 5 is an explanatory view showing a method for opening a molten metal tapping nozzle according to still another embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a simplified configuration of a sliding nozzle.
[Explanation of symbols]
1,14 Upper nozzle
2,15 Upper plate
3,16 lower plate
4,17 Lower nozzle
5,25 granular filler
6,26 Sintered layer
7,27 solidified layer
10 Ladle (refining ladle)
12 Sliding nozzle
13 Gas injection nozzle
18 Trout brick
20 molten metal (molten metal)
21 Brick with gas injection nozzle
24 nozzle holes
25 Porous refractory objects
26 Irregular refractory objects
27 Connecting pipe
28 Gas distributor
29 Gas supply pipe
40 electromagnetic induction device

Claims (6)

When opening the openable and closable molten metal tapping nozzle attached to the bottom or side wall of the molten metal container, and tapping the molten metal stored in this container out of the container,
Before and / or at the time of tapping, the molten metal near the nozzle is caused to flow by energy applied from outside the container so as to prevent a solidified layer from being formed in the nozzle. Opening method of the molten metal tapping nozzle to be used. As the energy to be applied from outside the container, the gas is ejected from the outside of the container into the molten metal stored in the vicinity of the molten metal tapping nozzle, or the molten metal stored in the vicinity of the nozzle is also electromagnetically induced, 2. The method for opening a molten metal tapping nozzle according to claim 1, wherein the molten metal stored near the nozzle is caused to flow. After filling the filler into the nozzle hole of the openable and closable molten metal tapping nozzle provided at the bottom of the molten metal container, the molten metal injected into and stored in the container is opened and the container is opened. When you go outside,
Before and / or at the time of tapping, an inert gas, a nitrogen gas, or a mixed gas thereof is ejected from the bottom outside the container into the molten metal stored in the vicinity of the molten metal tapping nozzle. 3. A method for opening a molten metal tapping nozzle attached to the molten metal container according to 1 or 2. 4. The molten metal container according to claim 1, wherein the molten metal container is a ladle for storing the molten metal or a smelting ladle for storing the molten metal and used for refining. 5. A method for opening a nozzle for molten metal tapping. The method for opening a molten metal tapping nozzle attached to a molten metal container according to any one of claims 1 to 4, wherein the molten metal tapping nozzle is a sliding nozzle. In a device for opening the openable nozzle for molten metal tapping attached to the bottom or side wall of the molten metal container, and for tapping the molten metal stored in the container to the outside of the container,
The container itself may be provided with a gas injection nozzle for ejecting gas in the vicinity of the molten metal tapping nozzle, or may be provided with an electromagnetic induction device for electromagnetically inducing molten metal stored near the molten metal tapping nozzle outside the container. The molten metal stored near the nozzle is flowed so as to prevent a solidified layer from being formed in the nozzle before and / or at the time of tapping. Opening device for molten metal tapping nozzle.

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