JPS60221158A - Continuous casting installation - Google Patents

Abstract

PURPOSE:To remove rationally the non-metallic inclusions suspended in a molten metal, for example, molten steel and to obtain a defectless continuous casting billet by providing a filter made of refractories. CONSTITUTION:A filter 7 is installed to partition the inside of a tundish 2 with the top end thereof projected from the surface of a molten steel in such a way that substantially whole of the molten steel from a long nozzle 3 to the inside of the tundish 2 flows toward the apertures 4 where pouring nozzles 6 are installed after passage through the filter 7. The filter 7 is adequately made of, for example, alumina refractories which allow permeation of the molten steel but can capture the non-metallic inclusions and have preferably internally communicating spaces of a three-dimensional network structure. A filter 8 made of the above-mentioned refractories is mounted to the long nozzle 3 in such a way that substantially whole of the molten steel flowing toward the tundish 2 from the nozzle 3 passes through said filter when necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to continuous casting equipment for producing sound continuous slabs by rationally removing nonmetallic inclusions suspended in molten metal, such as molten steel.

For example, in continuous casting of molten steel, as schematically shown in FIG. . To supply molten steel from the ladle 1 to the tundish 2, a long nozzle 3 whose upper end is connected to the bottom of the ladle 1 is used, and to guide molten steel from the tundish 2 to the mold 5, an injection nozzle 6 is used. Ru.

Conventionally, the long nozzle 3 has been a cylindrical body made of refractory material with open upper and lower ends. In this case, ladle 1
Connect the upper opening of this long nozzle 3 to the outlet provided at the bottom of the long nozzle 1, usually through a sliding nozzle,
The lower part of the long nozzle 3 was inserted into the tundish 2, and molten steel was flowed into the tundish 2 from the opening at the bottom of the long nozzle 3. Also Tanditshu 2
Injection into the mold 5 was also performed using an injection nozzle 6 with upper and lower openings that communicated the tundish 2 and the mold 3. Therefore, the non-metallic inclusions suspended in the molten steel in the ladle 1 also enter the tundish 2 together with the molten steel, and although some of them float up in the tundish 2, most of them remain in the mold 5.
Although they are floated and separated to some extent within the mold 5, some of them are captured by the solidified shell, which causes surface defects and internal defects in the continuously cast slab, and causes continuous casting of high-grade steel. This has caused problems such as inhibiting hot charging and direct rolling.

In order to solve this problem, conventional methods have been used to clean the molten steel itself in the ladle in the previous process, or to dam up non-metallic inclusions that have surfaced in the tundish. Methods such as installing a weir to prevent non-metallic inclusions from flowing into the mold were proposed or adopted. However, in the former case, the actual situation is that it is not very effective even though it requires extra processing. In the latter case, when the amount of hot water in the tundish decreases, such as at the end of casting, the weir will no longer be effective, so the height of the weir must be sufficient for floating non-metallic inclusions to be blocked by the weir. It is necessary to maintain the Therefore, even at the end of casting, a sufficient amount of hot water must remain in the tundish, which inevitably lowers the yield. Furthermore, even if this weir is provided, it only serves to dam up floating objects of non-metallic inclusions, and active separation of non-metallic inclusions cannot be expected completely.

As described above, in continuous casting, the separation of nonmetallic inclusions is a very troublesome problem, and there has been a strong desire to develop a formulation that is advantageous for operation and can effectively and reliably separate these inclusions.

The purpose of the present invention is to meet this need.

Equipment that reasonably achieves this purpose includes a ladle 1 for storing molten metal, a tundish 2 for also placing molten metal, one end of which is removably connected to an opening provided at the bottom of ladle 1, and the other end of which is a tundish. a long nozzle 3 inserted into the mold 5; and an injection nozzle 6, one end of which is connected to the opening 4 provided at the bottom of the tundish 2, and the other end inserted into the mold 5.
In the conventional continuous casting equipment consisting of
As shown in the embodiment of FIG. 2, inside the tundish 2, on the downstream side of the long nozzle 3 and on the upstream side of the opening 4, there is a refractory material that allows molten metal to pass through and that can trap non-metallic inclusions. Substantially all of the molten metal injected into the tundish 2 from the long nozzle 3 passes through the filter 7 made of refractory material before passing through the opening 4.
The present invention provides continuous casting equipment characterized in that it is installed so that the flow flows toward the flow direction. Furthermore, the long nozzle 3 is also equipped with a refractory filter 8 through which molten metal can pass and which can capture nonmetallic inclusions, so that substantially all of the molten metal flowing from the long nozzle 3 to the tundish 2 is removed. A facility is provided in which the refractory filter 8 is passed through. As the refractory filter 7 and the refractory filter 8 through which the molten metal can pass and which can trap nonmetallic inclusions, filters made of a refractory having a three-dimensional network structure with internal communication spaces are used. A more effective nickname.

The equipment of the present invention will be specifically explained below according to the drawings.

As shown in FIG. 2, in the present invention, a refractory filter 7 is inserted into the tundish 2 after substantially all of the molten steel supplied into the tundish 2 passes through the refractory filter 7. The nozzle 6 is installed so that it flows toward the opening 4 of the installation part. Since Fig. 2 shows an example of two sets of molds, the refractory filter 7 is also installed in three places, but substantially all of the hot water supplied to the injection nozzle 6 is filtered through the refractory filter 7 beforehand. As long as the relationship that the water passes through the material filter 7 is satisfied, no matter how many sets of molds there are, the number of refractory filters 7 corresponding to the number of sets may be provided.

The specific prescription that satisfies this relationship is the position of the long nozzle 3 inserted into the tandice pipe 2 and the injection nozzle 6.
A plate-shaped refractory filter 7 is placed between the bottom opening 4 to which the filter 7 is connected, and the upper end thereof protrudes beyond the screen. In other words, a plate-shaped refractory filter 7 is used to block the flow of hot water. It divides the inside. In this case, 9 the scene will be in contact with this refractory filter 7 as in the case of a normal weir, but 1 a normal weir is basically constructed of a material that does not allow hot water to pass through, and a hot water communication path is provided below the weir. In contrast, in the present invention, the material is made of a material through which hot water permeates, and there is no communication path for hot water to bypass the refractory filter 7, so that virtually all of the hot water passes through the refractory filter 7. They are fundamentally different in that they are constructed so that they flow through 7. The refractory filter 7 has an area large enough to cover the entire cross section of the hot water present in the tundish 2 (cross section perpendicular to the flow direction of the hot water). It may be configured such that the cross section is small, or it may be configured to be smaller than the entire cross section of the hot water. In the latter case, it is preferable to allow the hot water in the lower layer to pass through this filter function section.

The refractory filter 7 used has a nonmetallic inclusion filtering function that allows molten steel to pass through but can trap nonmetallic inclusions. As such a refractory, a refractory having a three-dimensional network structure with internal communication spaces is suitable. A porous refractory may be created by simply firing granular refractory powder in the presence or absence of a binder, but it is also possible to carbonize, remove, gasify or volatilize a portion of the base material during firing to form ceramic grains. In the case of porous ceramics in which internal communication spaces are formed in a complexly connected three-dimensional network structure, the pore surface area becomes extremely large, and the ability to trap nonmetallic inclusions in molten steel becomes high. Because the pore surface area is large, even if non-metallic inclusions are trapped, the flow of molten steel is not hindered to a large extent, and the number of uses can therefore be increased.The material of this porous refractory is Although there is no particular restriction as long as it is a durable refractory, an alumina-based refractory is used in the example shown in FIG.

Figure 3 shows a refractory filter 7 made of a porous refractory in which internal communication spaces with a three-dimensional network structure are formed.
An example of this is shown diagrammatically, and FIG. 4 shows a more enlarged pattern of the internal communication space of this three-dimensional network structure. As shown in the figure, this refractory has a structure in which three-dimensional lattices 10 are intricately intertwined.

In addition to installing a refractory filter 7 in the Kunditshuge 2, if a refractory filter 8 is also installed in the long nozzle 3, it is possible to produce even healthier slabs, and to prevent non-metallic materials from flowing outside the system. Inclusions can be easily removed.

FIG. 5 is an enlarged view of a part of the equipment shown in FIG. 2 in which a refractory filter 8 is attached to the long nozzle 3. The long nozzle 3 is connected to the opening provided at the bottom of the ladle 1 as described above.

It is removably attached from the outside (usually via a sliding nozzle). Conventional long nozzles have been attached to the ladle using a cylindrical body whose top and bottom ends are open, with both the top and bottom ends open to be inserted into the tundish. In the example of the present invention shown in FIG. 5, the lower end of this long nozzle is not simply an open end as in the conventional case, but a container-shaped refractory filter 8 with a bottom is attached below this long nozzle 3. be. Refractory filter 8 attached to this long nozzle 3. Also, the above-mentioned refractory filter 7
Similarly, it is preferable to use a porous refractory with a three-dimensional network structure and internal communication spaces.

As a result, all the molten steel moving from the ladle 1 to the tundish 2 passes through this refractory filter 8, and this filter 8 removes non-metallic inclusions suspended therein, ensuring a long service life. It can be captured with. When this long nozzle 3 is provided with the function of capturing non-metallic inclusions, this long nozzle 3 is detachably attached to the ladle 1, and the long nozzle 3 is attached to the ladle 1 in a removable manner, and the long nozzle 3 is attached to the ladle 1 virtually every time the steel is poured from the ladle 1 to the kundish 2. Since the nozzle 3 is removable, if the filter function deteriorates due to increased use, it can be replaced with a new one. Therefore, nonmetallic inclusions captured here can be removed from the system without the need for special operations. Can be easily removed outside.

After filtering out non-metallic inclusions with this long nozzle 3, a refractory filter 7 in the tundish 2 is further removed.
By filtering out non-metallic inclusions, molten steel with a significantly reduced concentration of non-metallic inclusions is poured into the mold 5, making it possible to produce a healthier slab. In this case, the load on the refractory filter 7 in the tundish 2 for filtering out non-metallic inclusions is greatly reduced, so the service life of the refractory filter 7 is increased, and the number of replacements is reduced.

In addition, as shown in FIG. 2, this refractory filter 7
It is preferable to form a layer of nine varnish slags 9 on the molten steel upstream of the molten steel.

FIG. 6 shows the two-set mold equipment shown in FIG. 2, with a refractory filter 8 installed in the long nozzle 3 and a refractory filter 7 installed in the tundish 2.

Changes in non-metallic inclusions in slabs between the case of installation and operation with the above-mentioned relationships and the conventional case where these were not installed (the first non-metallic inclusions in slab in the present invention) L is organized by the number of times Tandish is used. The tanditshu had a capacity of 180 tons/time, and the molten steel tested was Cjo, 06%,
Si: 0.01%+Mn: 0.30%, P: 0.
010%, S: 0.010%, So1. AI
:0.040% low carbon aluminum killed steel, which was cast at a casting speed of 1.4 m/+win (180t/ch,
) and was cast in a 250*m x 1050mm slab mold.

In addition, the refractory filter 8 can secure a discharge volume equivalent to the discharge volume of the conventionally used long nozzle 4 with a nozzle hole of approximately 100 m5+φ.

A product molded into the shape shown in FIG. 3 was used. As shown in FIG. 6, according to the present invention, the number of nonmetallic inclusions in the slab can be greatly reduced. It can be seen that in the conventional case, the number of non-metallic inclusions in the slab gradually increases as the tundish is used, whereas in the present invention, it can be maintained at a completely constant low level.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an outline of conventional continuous casting equipment, FIG. 2 is a schematic sectional view showing an example of the casting equipment of the present invention, and FIG. 3 is a perspective view showing an example of a refractory filter. Fig. 4 is an enlarged view showing an example of the internal structure of a refractory filter, Fig. 5 is a schematic cross-sectional view showing an example of a long nozzle used in the present invention, and Fig. 6
The figure is a graph showing the amount of nonmetallic inclusions in the slab when using the equipment of the present invention in comparison with the conventional method. 1. Ladle, 2. Tanditshu. 3. Long nozzle, 4. Opening at the bottom of the tundish, 5. Mold, 6. Injection nozzle. 7. Refractory filter, 8. Refractory filter. Figure 3 @ Figure 4 Figure 6

Claims (1)

[Scope of Claims] (l) A ladle 1 into which molten metal is placed, a tundish 2 into which molten metal is also placed, one end of which is removably connected to an opening provided at the bottom of the tundish 2, and the other end is inside the tundish 2. Long nozzle 3 inserted into. In a continuous casting equipment comprising an injection nozzle 6 whose one end is connected to an opening 4 provided at the bottom of the tundish 2 and whose other end is inserted into the mold 5, the injection nozzle 6 is inserted into the tundish 2 downstream of the long nozzle 3 inside the tundish 2. Continuous casting equipment characterized in that a refractory filter 7 is installed upstream of the opening 4 and is capable of transmitting fs molten metal and capturing non-metallic inclusions. (2) The continuous casting equipment according to claim 1, wherein the refractory filter 7 is made of a refractory having an internal communication space with a three-dimensional network structure. (3) A ladle 1 for holding molten metal, a tundish 2 for holding the molten metal, and a long nozzle whose one end is removably connected to the opening provided at the bottom of the ladle l and the other end is inserted into the tundish 2. 3 and. In a continuous casting equipment consisting of an injection nozzle 6' whose one end is connected to the opening 4 provided at the bottom of the tundish 2 and whose other end is inserted into the mold 5, molten metal is poured into the detachable long nozzle 3. A refractory filter 8 that is permeable and capable of capturing non-metallic inclusions is inserted into the long nozzle 3.
It is installed so that substantially all of the molten metal heading from the tundish 2 toward the tundish 2 passes therethrough, and there is a hole in the tundish 2 downstream of the long nozzle 3 and upstream of the opening 4 through which the molten metal can pass. Continuous casting equipment characterized by installing a refractory filter 7 capable of capturing metal inclusions. (4) The continuous casting equipment according to claim 3, wherein the refractory filter 7 and the refractory filter 8 are made of a refractory having an internal communication space of a three-dimensional network structure.