JP2866309B2 - Filling method of filling material for opening for molten metal pouring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling a filler into an opening for discharging molten metal (comprising a nozzle and a refractory near the nozzle) provided at the bottom of a molten metal processing container. The present invention relates to a method for filling a filling material into an opening including a nozzle provided at the bottom of a processing container such as a ladle or a tundish.

[0002]

2. Description of the Related Art In general, a method of injecting molten steel into a mold such as a continuous casting machine is to temporarily receive the molten steel in a ladle, and then to open the molten metal pouring opening (hereinafter, referred to as a bottom) provided in the bottom of the ladle. This is performed through a tundish (in some cases, a tundish is not used) rather than through an opening. Therefore, the opening is closed when receiving hot water and opened when pouring into the mold. In recent years, a so-called sliding nozzle capable of closing and opening the nozzle by sliding a plate and controlling the amount of molten metal has been adopted in the opening.

In the use of a ladle or tundish having the above-mentioned sliding nozzle, a nozzle and a sliding plate are attached to a bottom portion of the ladle or a tundish, and as shown in FIG. ) Is filled with sand (filler) 3. The sand 3 is heated to a high temperature at a portion in contact with the molten steel 4 after receiving the hot water to form a sintered layer, and the molten steel 4 is prevented from solidifying on the sliding plate 1 or is formed under the sintered layer. The sand that is located is not sintered and maintains its original state. Then, when the plate is slid in the opening direction to pour the molten steel into the mold, the sand in the non-sintered state immediately falls by itself, and the sintered layer portion is broken by the molten steel static pressure to open, and the molten steel is opened. Can be poured into a mold.

Since the state of filling of this sand (usually, silica sand having a round particle size) affects the material of the cast steel, a method of filling and removing the sand has been conventionally studied.
It has been developed and there are many patent applications. For example, JP-A-56
Japanese Patent Publication No.-0101163 proposes a hot water dispenser for a ladle for continuous casting, in which a swing arm having an independent support structure to which a discharge gutter is attached and a drive device for moving the discharge trough between predetermined positions are arranged. A technique is disclosed in which, at the beginning of the operation, sand and low-temperature molten metal can be discharged safely out of the mold at an early stage, albeit adversely affecting the operation safely and easily, irrespective of human power. Japanese Patent Laying-Open No. 58-154452 discloses an apparatus for preventing the nozzle filling of a ladle from being mixed into molten steel, in which the upper portion of a cylindrical container has a soluble or flammable structure, and the cylindrical container is disposed immediately below the ladle nozzle. An apparatus has been disclosed which effectively and simply prevents the nozzle filling from dropping into the mold by being inclinedly disposed so as to be positioned at a position. Further, Japanese Patent Application Laid-Open No. 63-238971 discloses that a filling formed by previously filling a powdery substance at the outlet of a molten metal,
Disclosed is a method for improving the yield and quality by supplying gas to float the filling on the surface of the molten metal after the molten metal is stored in the container and then pouring the molten metal into another container. Japanese Patent Application Laid-Open No. 64-048662 specifies the composition of sand packed in a ladle nozzle to be 98% by weight or more of SiO ₂ and less than 1% of an alkali oxide to greatly improve the natural opening ratio of the nozzle and to improve the operation. He showed the technology to greatly reduce trouble.
Here, the natural opening ratio of the nozzle means that even if the sliding plate is opened, the sand does not drop or flow out, that is, does not naturally open, so the frequency of opening immediately is evaluated as the natural opening ratio. .

On the other hand, as described above, silica sand containing SiO ₂ as a main component is generally used as a nozzle filler, and the upper portion of the sand directly in contact with molten steel is heated to a high temperature and sintered.
The portion below the sintered layer remains powdery and flows into the tundish prior to starting the injection of molten steel into the mold. Sand flowing into the tundish is readily reacts with Al in the steel according _{3SiO 2 + 4Al → 3Si + 2Al} 2 O 3 ... (1) (1) formula, Al ₂ O
₍₃₎ Inclusions reduce the cleanliness of the molten steel or flow unreacted into the mold and become inclusions as they are. From the above points, when continuously casting high cleanliness steel, when sand is used as the nozzle filler, it is not preferable that the sand flows into the tundish.

[0006] Therefore, in continuous casting of high cleanliness steel, the following two measures have been considered in order to avoid the adverse effects caused by the increase in the amount of Al ₂ O ₃ inclusions caused by the sand. One means is to use silica sand whose main component is SiO ₂ as a filler, but the time at which the sand flows is limited immediately after the opening of the nozzle, and at that time, the sand flows into a tundish or a mold. To prevent For example, JP-A-56-11163 and JP-A-58-154452 disclose that even if sand is used as a filler, the nozzle filler can flow into a tundish or a mold by using a dedicated sand removing device. A technique for preventing such a situation has been disclosed. However, these techniques require a special sand removing device for them, require a large amount of equipment cost, and are difficult to put into practical use. In addition, Japanese Patent Application Laid-Open No.
Although the technique described in Japanese Patent No. 238971 can prevent the sand from flowing into the tundish or the mold, the sand is dispersed in the molten steel immediately before the start of the pouring, and is completely eliminated from the adverse effect of increasing the inclusions according to the formula (1). I cannot escape.

[0007] On the other hand, another means is that the sand is hardly reactive with respect to the above formula (1) (for example, alumina,
Magnesia, etc.), and this method does not require special equipment and can minimize the investment amount. However, the hard-to-react filler is seized on the nozzle refractory (usually alumina or magnesia),
There is a problem that the natural aperture ratio of the nozzle is significantly reduced.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can maintain the natural opening ratio of a nozzle at 99% or more.
Further, it is an object of the present invention to provide a new filling method which enables the use of a nozzle filler which does not easily react with Al dissolved in steel.

[0009]

In order to achieve the above object, the inventor of the present invention has a problem when employing a non-SiO ₂ nozzle filler which does not react with dissolved Al in steel according to the formula (1), The method of preventing seizure of the refractory and the filler material of the nozzle was studied diligently, and attention was focused on spraying an anti-seizure agent (release agent) on the inner wall of the nozzle under a high temperature environment of 800 ° C. or more.
The present invention is an embodiment of the present invention, when filling the filler in the molten metal pouring opening provided in the bottom of the molten metal processing vessel and having a slide opening and closing plate, before filling the filler, 20-30 on the inner wall of the opening
The weight% of P ₂ O _5, and 15 to 20 wt% of graphite, 1
A method for filling a filler for opening a molten metal, comprising applying an anti-seizure agent for the filler composed of 5% by weight of SiC and the balance of water . Further, the present invention comprises an upper Symbol filler, alumina, alumina spinel and melt pouring opening filling method of filling material, characterized in that it consists of one or more selected from magnesia.

[0010]

According to the present invention, when filling the filler into the opening for pouring the molten metal having the slide type opening / closing plate provided at the bottom of the molten metal processing container, before filling the filler, the inner wall surface of the opening is filled with the filler. ３０30% by weight of P ₂ O ₅ and 1
5 to 20% by weight of graphite, 1 to 5% by weight of SiC,
Since the anti-seizure agent of the filler consisting of water was applied, the filler did not seize on the inner wall surface of the opening,
When the molten steel is poured into a mold or a tundish, the filler easily falls. In the present invention, the upper Symbol filler, alumina. Thus composed of one or more selected from alumina spinel and magnesia, the effect is to be further promoted.

Hereinafter, the anti-seizure agent according to the present invention will be supplemented a little. The anti-seizure agent may have any composition as long as it is a liquid at normal temperature depending on the shape of the application surface, such as the inner wall of the nozzle and the refractory in the vicinity thereof. However, when the opening filler is made of aluminum, aluminum spinel and magnesia as a main component in consideration of the reaction with dissolved Al in steel according to the above formula (1), the anti-seizing agent is phosphoric acid. And graphite powder,
It is preferable to consist of SiC powder and the balance water.

Phosphoric acid is a high-concentration phosphoric acid aqueous solution of P ₂ O ₅ ≧ 30%, and its purpose is to remove graphite powder which acts to easily release the filler from the surface of the high-temperature nozzle refractory. An object of the present invention is to form a coating layer of an anti-seizure agent having a thickness of about 1 to 2 mm by attaching to the refractory surface of the opening. Further, the SiC powder is dispersed on the inner surface of the coating layer, and functions to prevent the layer from being exposed to the atmosphere and being oxidized and lost.

[0013] Next, the reasons for limiting the graphite powder are as follows.
Since the releasing effect of the anti-seizure agent is obtained by the graphite powder, the releasing effect increases as the proportion of the graphite powder increases. However, when the proportion of the graphite powder is increased, it becomes difficult to form a graphite layer on the inner wall surface of the opening. In the present invention, an experimental study was carried out in which the mixing ratio was changed variously, and 15
In the operating temperature range of 00 ° C to 1800 ° C, 15 to 2
It was found that 0% of the compounding ratio was a compounding ratio capable of achieving both the releasing effect and the layer moldability. In addition, in order to prevent the graphite powder from being oxidized at about 1800 ° C. for 2 hours in the air atmosphere after the coating layer is formed, the amount of SiC needs to be 1/4 by weight with respect to the graphite powder. If the temperature is 1500 ° C. for 30 minutes, it may be 1/15. Furthermore, the reason that the mixing ratio of P ₂ O ₅ is 20 to 30% by weight is that if it is 20% by weight or less, the coating layer after application is brittle, and the graphite powder becomes difficult to adhere to the inner wall surface of the opening, and 30% by weight or more. In this case, not only does it take time to solidify the coating layer, but it also increases the cost of the anti-seizure agent.

[0014]

【Example】

(Example 1) A with a molten steel processing capacity of 235 tons / charge
A steel having the composition shown in Table 2 was received in a ladle lined with l ₂ O ₃ -MgO-based refractory using the silica-less opening filler shown in Table 1, and at a rate of 45 minutes / charge. 16 charge continuous casting was performed. The ladle used at that time is symbol A ~
The four batteries up to D were used in exchange from A for 4 charges each.

After completion of casting, the A pan and the C pan are coated with the anti-seizing agent having the composition shown in Table 3 according to the present invention before filling with the filler of the next charge, and dried for 10 minutes. And the sliding nozzle was opened to pour steel into a tundish. On the other hand, the B pan and the D pan were poured without applying any anti-seizure agent. In addition, A to D pans are filled pots,
As a result of making the cycle time of the empty pan the same, the surface temperature of the inner wall of the nozzle before filling the filler of the next charge,
All charges were set to be almost uniform at 830 to 845 ° C.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

The effects of the present invention are as follows: the time from when the sliding plate is opened at the start of casting to the time when molten steel is actually started to be poured (hereinafter referred to as the required pouring time); The evaluation was made on the adhesion state of the inner wall surface of the opening. FIG. 1 shows the relationship between the required pouring time and the pot used. According to FIG. 1, the B pan and the D pan to which the anti-seizure agent is not applied without applying the method of filling the opening filler according to the present invention open naturally at the third charge and the fourth charge, respectively. Oxygen was blown from below the opening to open the hole without opening. In addition, even in the first charge and the second charge in which the holes were spontaneously opened, the A pot and the C
Compared with a pot, the time required for pouring was 5 to 10 seconds longer. A using the filling method of the opening filler according to the present invention
Each of the pot and the C pot was stable, with the time required for spontaneous opening up to the fourth charge being less than 2.5 seconds.

FIG. 2 shows a C pot (FIG. 2) to which the present invention is applied.
(A)) and the D pan (see FIG. 2 (B)) that was not applied are shown as results after investigating the state of adhesion of the inner wall surface of the opening as an empty pan after casting the second charge. From FIG. 2, no deposits were observed in the C pan, whereas the deposits were observed in the D pan over the entire inner wall of the nozzle. As a result of analysis, it was found that the deposit was a sintered product of the filler. The filler that has fallen into the tundish together with the molten steel does not undergo the reaction of the formula (1), and then floats off as slag and is removed. (Example 2) A filling method according to the present invention using the silica-less filler shown in Table 1 and the anti-seizure agent shown in Table 3, and a filler containing silica as a main component shown in Table 4 without using an anti-seizure agent Conventional filling methods were compared. At that time, the continuous casting conditions other than the opening filler and the anti-seizure agent were the same as in Example 1, and the two were completely the same.

[0021]

[Table 4]

The results were evaluated based on the representative oxygen value of the molten steel in the tundish and the defect occurrence rate due to Al ₂ O ₃ inclusions when the slabs as cast products were formed into cold rolled plates. Are shown together. Using silica-less filler,
When the method of the present invention is applied, both the representative oxygen of the molten steel in the tundish and the defect rate of the cold-rolled sheet are low, and it is clear that the method is effective for the production of high cleanliness steel.

[0023]

[Table 5]

[0024]

As described above, according to the present invention, it is possible to use an opening filler such as alumina, alumina spinel, magnesia, etc., which cannot be used conventionally, for pouring molten metal.
At the opening at the bottom of the molten metal processing container, the natural opening ratio has been improved compared to the conventional case.

[Brief description of the drawings]

FIG. 1 is a diagram comparing the performance of a filling method according to the present invention with that of a conventional method.

FIGS. 2A and 2B are views showing a vertical cross section of a sliding nozzle, in which FIG. 2A shows a state to which the present invention is applied, and FIG.

FIG. 3 is a longitudinal sectional view showing a state where sand is filled into an opening employing a sliding nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sliding plate 2 Inner wall of opening 3 Filler (sand) 4 Molten steel 5 Nozzle refractory 6 Tuyere refractory

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 103: 00) C10N 40:36 (72) Inventor Takamitsu Sano 1 Kawasaki-cho, Chuo-ku, Chiba-shi Kawasaki Steel Corporation Chiba Steel Development & Production Headquarters Inside the steelworks (72) Inventor Sumio Yamada 1 Kawasaki-cho, Chuo-ku, Chiba Kawasaki Steel Co., Ltd. (56) References JP-A-61-180667 (JP, A) JP-A-57-121871 (JP, A) JP-A-5-169242 (JP, A) JP-A-5-329623 (JP, A) JP-A-5-31573 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 41/46 B22D 11/10 340

Claims (2)

(57) [Claims] When filling a filler into an opening for pouring a molten metal provided at a bottom portion of a molten metal processing vessel and having a slide-type opening / closing plate, before filling the filler , 20 to 20 mm may be provided on an inner wall surface of the opening.
30% by weight of P ₂ O ₅ and 15 to 20% by weight of graphite;
A method for filling a filler for opening molten metal, comprising applying an anti-seizure agent for the filler comprising 1 to 5% by weight of SiC and the balance of water . 2. The method according to claim 1 , wherein the filler is alumina or alumina spin.
2. The method according to claim 1, comprising at least one selected from the group consisting of flannel and magnesia .