JPS6156758A - Method and device for preventing outflow of slag - Google Patents

Abstract

PURPOSE:To close the supply port of an intermediate vessel in preference to the outflow of slag and to prevent the outflow of the slag by pouring a molten steel into a tundish via the intermediate vessel having a floating closing body which is adjusted in bulk specific density from a ladle. CONSTITUTION:The floating closing body 6 in the intermediate vessel 2 is the closing body having the bulk specific gravity larger than the bulk specific gravity of the slag 7 and smaller than the bulk specific gravity of the molten steel 5 and has the spherical or polyhedral shape smaller than an upper aperture 8 which is a port for accepting the molten steel into the vessel 2 and larger than a lower aperture 9 which is the port for supplying the molten steel to the down stream tundish 3. The molten steel is contained from the ladle 1 through the nozzle 10 into the vessel 2 in the stage of pouring. The body 6 floats on the molten steel in this state and does not hinder the pouring of the molten steel 5 into the tundish 3. The body 6 closes the port 9 in precedence to the outflow of the slag 7 when the molten steel 5 in the ladle 1 is supplied together with the slag 7 to the vessel 2 on progression of casting into a casting mold 4.

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to continuous casting of steel, especially cast iron. Continuous casting of materials of different quality is carried out by replacing 11゛4 one after another. This is related to preventing slag from flowing into.

(Prior art) In order to improve the operation rate of continuous casting machines and greatly improve the yield of cast pieces, we have been using continuous casting machines that spin a large number of charges of /S steel of different materials in one cast. In other words, continuous continuous casting has been carried out.

On the other hand, was it well received by Ladle? '3 When injecting steel into the tundish, the flow rate of the molten steel is controlled using a sliding nozzle or the like. Regarding the operation of the sliding nozzle, the bottom contractor must visually monitor the hue change of the molten steel flow, determine whether slag has come out, and then operate a switch to close the sliding nozzle. However, such a judgment involves a delay in RA recognition, individual differences in judgment, etc., and a certain amount of molten slag flows out due to the eddy current entraining the slag in the steel. The molten slag that has flowed out in this way gets caught up in R314, and some of it floats up inside the tundish or mold, while some of it gets caught up in the slab and becomes inclusions.
In addition, a part of it acts as an accelerator for melting and damage of the immersion nozzle, which in turn inhibits casting.

In order to prevent such slag outflow into the tundish, methods for detecting the start of slag outflow from the ladle at the end of pouring include, for example, an electromagnetic method (Japanese Patent Application Laid-open No.
9-1430, Japanese Patent Publication No. 51-3109, Japanese Patent Application Laid-Open No. 51-112433), methods using X-rays, γ-rays, etc. (Japanese Patent Application Laid-open No. 51-101731, etc.), melting fully bent nozzles m (1) A method that utilizes the lift-off fluctuation electric signal generated in the coil due to the operation of the nostle (1')
Japanese Patent Application Publication No. 1973-! 117847), and a method of closing the sliding nozzle by measuring the lowering position of the molten steel surface in the ladle ('t, Ii 117
549) have also been proposed.

(Problem to be solved by the invention) However, 1. In all of these methods, the sliding nozzle is closed after the slag has flowed out or when the slag is on the verge of flowing out, and they are hardly ever put into practical use. '1 even if it becomes
8 Let 100% of tTA flow into the tundish,
100% of the slag may not remain in the ladle, and depending on the timing of closing the sliding nozzle, i9 SV
By leaving I in the ladle, the slag will also flow out between the tundishes.

(Means for Solving the Problems) The present invention was devised after repeated studies in view of the above-mentioned circumstances, and all molten steel and slag are once placed between the ladle and the tundish. It is allowed to flow into an intermediate container, where it is temporarily retained. Therefore, the slag that flows out at that time is stored and left in the intermediate container and is floated and separated from the molten steel, so that only the molten steel is supplied to the tundish.

Therefore, the gist of the present invention is to provide an intermediate container for temporarily retaining molten steel between a ladle and a tundish, and a receiving port for receiving the molten steel flow from the upstream ladle and a tundish downstream of the molten steel. a supply port for supplying molten steel, the interior of the intermediate container has a horizontal cross section large enough to close the supply port, and smaller than the specific gravity of the molten steel;
This is a device for preventing slag outflow in a tundish for continuous casting, which is constructed by inserting a floating blocker having a bulk specific gravity greater than the specific gravity of slag.

Furthermore, according to another feature, the gist of the present invention is to provide a receiving port between a ladle and a tundish for receiving a flow of molten steel from the ladle and a molten steel downstream in continuous casting of steel, particularly in continuous continuous casting. An intermediate container is provided which has a supply port for supplying the molten steel to the tundish and temporarily retains the molten steel, and a floating blocker having a high specific gravity that floats at a position between the /8 steel and the slag is introduced into the intermediate container. Under this condition, molten steel is injected from the ladle into the tundish through the intermediate container, and when the ladle is replaced, the lower supply port of the intermediate container is closed with the floating blocker to mix the molten steel in the tundish. This is a method for preventing slag from flowing out in a continuous casting tandy 7-shu, which is characterized by separating the slag from the slag in the intermediate container.

Thus, although the present invention is applicable to continuous casting in general, it is particularly advantageously applied to the so-called continuous continuous casting method.

That is, according to the present invention, there is virtually no slag flowing into the tundish, so deterioration in the quality of the boundary material is prevented even during continuous casting of dissimilar materials, and on the other hand, mixing of molten steel in the front and rear charges is also prevented. effectively prevented. After all of the molten steel from the previous charge has been injected into the mold, it is possible to receive the molten steel from the subsequent charge into the tendinoyu via the intermediate container.

As already mentioned, when pouring molten steel from a ladle into a tundish, a portion of slag is poured into the /8 steel flow, but in the present invention, a portion of slag is poured from the ladle into the intermediate container.
Even if the steel stream is allowed to flow down, if the intermediate container is sufficiently deep,
That is, as long as the residence time in the intermediate container is long enough, there is actually no problem in flotation and separation of the entrained slag.

Regarding the differences in the ratios of molten steel, slag, and floating blockages, generally the high strength of the floating blockages is selected to be between the other two, but it is said that slag outflow prevention when press-fitting /8 steel is selected. For this purpose, it is preferable that the closing surface, that is, the outer peripheral surface (line) of the floating closing body when the supply port is closed with the floating closing body be selected so as to correspond to the water line with the molten steel during floating.

(Function) Hereinafter, the present invention will be briefly described based on embodiments shown in the accompanying drawings.

FIG. 1 is a schematic diagram showing a situation in which /8 steel 5 is press-fitted into a mold 4 from a ladle 1 via an intermediate container 2 and a tundish 3 during continuous casting.

In the figure, a floating blocker 6 is placed in the intermediate container 2, and the blocker 6 has a bulk specific gravity larger than that of slag 7 and smaller than that of molten steel 5, such as a ball or a ball made of refractory material. This is a simple polyhedral closure. For example, f46m
The ratio of m7.2, the ratio of slag ゛1 weight 3.0
In this case, if the floating blockage m is set to 5, the molten steel and slag can be completely separated. Although its shape and structure are not particularly limited, it is a receiving port for the /8 steel flow of the intermediate vessel 2, which is smaller than the upper opening 8 and smaller than the lower opening 9, which is the supply port for molten steel to the downstream tundish. Larger 1mm (preferably 1mm larger than the hole diameter of the lower opening)
It is in the form of a sphere or polyhedron with 2 to 2 members).

As shown in FIG. 1, since the floating plug 6 has a larger ratio m than the slag 7, a part of the floating plug 6 is suspended in the slag 7 while being covered with the /8 steel 5. As already mentioned, it is preferable that the floating blocker closes the lower opening 9 at the position of the water line with the /8 steel.

When /8 steel is poured, first, the molten steel flowing down from the ladle 1 through the nozzle 10 is temporarily stored in the intermediate container 2, and the slag and /8 steel are separated within the residence time. At this time, the floating blocker 6 is floating on the molten steel and does not become an obstacle to the pouring of the /8 steel 5 into the tundish 3. The /8 steel 5 injected into the tandate is then further 'tl
? It is injected into the mold 4 through the a nozzle 11. In the illustrated example, a two-strand type is shown.

As the casting progresses in this way, and all of the molten steel in the ladle 1 is supplied to the intermediate container together with slag, the slag line in the intermediate container 2 descends as the molten steel 5 is poured, and Approaching 9.

However, in the case of the present invention, the floating blocker 6 with adjusted bulk specific gravity
Since slag is charged, the floating blocker 6 closes the supply port 9 prior to the outflow of the slag, thereby preventing the outflow of the slag.

In order to prevent oxidation of the molten steel flow, it is preferable to seal the space between the nozzle 10 and the upper opening 8, which is the receiving port, using an inert gas such as argon gas. Further, at least the bottom of the intermediate container 2 is connected to the l container 5 in the tundish 3.
It is also preferable to have a structure in which the liquid is immersed in water.

Next, Fig. 2 is an explanatory diagram schematically showing the situation when pouring from inside the ladle is finished, the ladle is removed, and the intermediate container 3 is lifted up. In the figure, all the /8 steel in the intermediate container 2 is The slag 7 flows out into the tundish 3 and the floating blocker 6 closes the lower opening 9 of the intermediate container 2, so that the slag 7 remains in the intermediate container 2.
The outflow into Tandy and Shu 3 is blocked. In this way, the intermediate container r:r2 was lifted up and removed outside of Tandei Nonyu, and as shown in the same schematic diagram in FIG. 3, another intermediate container 2'' prepared separately was installed, and then Install ladle 1, which received molten steel 5, and then add ladle 1,
Then, molten steel 5' is injected and supplied to the tundish 3 through the intermediate container 2'. In the illustrated example, the bottom of the intermediate container 2' is not crushed by the Tandinosier/S steel.

Therefore, according to the present invention, by repeating the above operations, all of the molten steel in the ladle 1 can be injected into the tandish 3 without causing any of the slag 7 to flow into the tandish 3. .

[Brief explanation of the drawing]

Figure 1 is a schematic explanatory diagram showing the situation in which molten steel is being poured into the tundish from the ladle through the intermediate vessel; Figure 2 is a schematic explanatory diagram showing the situation during lifting of the intermediate vessel; and Figure 3 is , is an explanatory diagram of the same type 103 showing a situation in which pouring of molten steel into a replaced intermediate container is started from a new container. 1: Ladle 2: Intermediate container 3: Tundishu 4: Ruby 5: Molten steel 6:
Closure body 7: Slag 8 2. Upper opening 9: Lower opening

Claims (4)

[Claims] (1) An intermediate container installed between the ladle and the tundish for temporarily retaining molten steel, which has a receiving port for receiving the molten steel flow from the upstream ladle and a supply port for supplying the molten steel to the downstream tundish. A floating blocker having a horizontal cross section large enough to block the supply port and having a bulk specific gravity smaller than the specific gravity of molten steel and larger than the specific gravity of slag is inserted into the intermediate container. A slag outflow prevention device in a tundish for continuous casting. (2) The apparatus according to claim 1, wherein at least the bottom portion of the intermediate container is immersed in the molten steel in the tundish. (3) The apparatus according to claim 1 or 2, wherein the interior of the intermediate container is isolated from the surrounding atmosphere by providing a sealing mechanism at the receiving port for the molten steel flow. (4) During continuous casting of steel, there is a receiving port between the ladle and the tundish that receives the molten steel flow from the ladle and a supply port that supplies the molten steel to the downstream tundish, and an intermediate part where the molten steel is temporarily retained. A container is provided, and a floating blocker having a bulk specific gravity such that it floats at a position between the molten steel and the slag is put into the intermediate container, and then from the ladle to the tundish via the intermediate container. Continuous casting, characterized in that molten steel is injected, and when the ladle is replaced, the lower supply port of the intermediate container is closed by the floating closure to separate the molten steel in the tundish from the slag in the intermediate container. Method for preventing slag from flowing out in a tundish.