JPS6159828B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to containers such as ladles and tundishes for transporting or retaining molten metal, in which the molten metal is poured out using a sliding nozzle type (not a stopper nozzle type) flow control device. The present invention relates to a method for opening a spouting channel in a case where the spouting channel is opened.

As is well known, the flow rate control device for molten metal containers is
A plurality of refractory plates installed under the upper pouring nozzle brick provided at the bottom of the container are slid or rotated by hydraulic pressure or electric power to adjust the opening degree of the holes drilled in the plates. For example, when molten steel is first received into a container, the molten steel first enters the hole in the elongated cylindrical upper nozzle brick (i.e. pouring nozzle) installed at the bottom of the container. The molten steel falls and is filled, but before the container is filled and the pouring operation begins, the molten steel in the upper nozzle brick cools and solidifies, blocking the nozzle hole, so pouring out the molten steel, or casting. Work becomes difficult.

In order to prevent this, as shown in FIG. 1, the pouring hole of the upper nozzle brick 3 is filled with powder resistant material 7 in advance and the first steel receiving is performed. That is, Fig. 1 is a vertical cross-sectional side view of a part of the bottom of the molten metal container, where 1 is the bottom refractory of the container, 2 is the outer shell, 3 is the upper nozzle brick, 4 is the flow rate control device, and the upper part is the fixed plate brick. , the lower part is a sliding plate brick, and 5 is a collector nozzle for consolidating the falling direction of the poured steel. 6 is the molten steel stored in the container, and 7 is the powder refractory filled in the hole of the upper nozzle brick.
That is, when the flow rate control device 4 is fully opened after receiving the molten steel 6 , the powder refractory 7 first falls through the collector nozzle 5, and then the uncooled molten steel 6 flows out naturally without any artificial means. The nozzle hole is opened naturally, but even with this method, the nozzle hole may become blocked and not open.
Currently, the natural aperture rate remains at 70-90%.

To explain the reason why it does not open with a schematic diagram, Fig. 2 shows the upper part of the powder refractory 7 packed in the nozzle hole of the upper nozzle brick 3 in Fig. 1, but Fig. The previous state and Figure b show the state several minutes have passed after receiving the steel.
1650°C) penetrates into the surface layer of the powder refractory 7, the powder refractory 7 mainly composed of silicic acid (SiO ₂ ) is sintered to form a strong wall, and eventually the surface layer The area becomes vitrified as shown in Figure 8. As the molten steel residence time increases, the molten steel above the powder refractories is further cooled and solidified, and the sintered wall 8 becomes thick and strong, so even if the powder refractories are dropped,
As shown in Figure d, the solidified bridge 9 is strongly sintered.
is suspended in the air and cannot be broken by the static pressure of the molten steel 6 alone.

The formation of such solidification bridges 9 depends on factors such as the temperature of the molten steel, the residence time of the molten steel in the container, the stirring condition of the molten steel, the refractory degree and packed area of the powder refractory, etc.
The thickness, strength, and shape of the bridge vary, and the static pressure of the molten steel (approximately 100 to 200 kg/ ^cm2 ) varies depending on the size and type of the container. , the nozzle aperture ratio will fluctuate.

If the bridge 9 does not open naturally as planned, the bridge 9 must be destroyed manually. Normally, this work is carried out by inserting an iron pipe from the bottom of the flow control device and spraying oxygen onto the bridge area to generate high temperature and melt it. A cylindrical collector nozzle 5 is installed, and recently a long nozzle has been installed below it to prevent air oxidation during injection casting of molten steel, making manual opening work extremely difficult. Not only is this common, but it is also dangerous, and it can also damage the nozzle hole refractories. In addition, if such opening work takes time, the casting work will not proceed smoothly, and especially in continuous casting operations using the continuous casting method, the supply of molten steel will be interrupted between the front ladle and the rear ladle, making it difficult to operate the entire continuous casting machine. This results in the inconvenience of having to restart the operation by restarting the steel receiving system from the beginning.

Therefore, in order to bring the natural aperture ratio closer to 100%, each company has developed the following methods, but the natural aperture ratio remains at around 90% and a complete solution has not yet been reached. be.

In order to minimize the penetration of molten steel into the refractory particles, the particle size of the sand is made as small as possible and the filling surface is made as flat as possible.

In order to suppress the floating of refractory particles and their sintering and vitrification, silicic acid (SiO ₂ ) particles are switched to zirconia (ZrO ₂ ) particles, which have a large specific gravity and high fire resistance.

By increasing the amount of refractory particles to be filled and widening the upper surface, the area of the bridge is increased, thereby weakening the support strength and making it easier to break under loads from above.

This invention improves the drawbacks of the prior art as described above and provides an opening method that increases the natural opening ratio of the pouring nozzle hole in a molten metal container to nearly 100%. Inclusions (lids) that minimize direct contact with refractory particles
The inclusions are a fragile material that is easily changed and carbonized by the high temperature of the molten metal, and does not form a hard reaction product even when carbonized, and at the same time, it is easy to form refractory particles with the lid on. This method allows for filling. That is, a lid made of an easily carbonizable material and provided with a hole for filling refractory particles and a large number of holes for venting air is fitted onto the upper end of the upper nozzle brick hole, and the filling hole is used to fill the lid. After filling the nozzle hole with refractory particles and then receiving the molten metal, if the refractory particles are allowed to fall when starting casting, the cap of the carbonized material, which is already weakened by itself, will easily fall under the load of the molten steel, causing This is a pouring hole opening method for molten metal in which the pouring hole opens naturally.

To explain the opening method of the present invention based on drawings showing an embodiment, FIG. 3 is a perspective view of a lid 10 made of an easily carbonizable material that fits into the upper end of the upper nozzle brick hole for pouring of the ladle. . The entire body is made of a mixture of cellulose, rubber, and/or a heat generating agent, such as a mixture of 90% cellulose fiber treated with waste paper, 5% liquid synthetic rubber, and 5% heat generating agent, or a mixture of 90% wood chips and 10% synthetic rubber. % is formed into a substantially cylindrical shape as shown in FIG. 3 using a mold, and an iron plate 11 and a pipe 12 for filling refractory particles are joined to the upper part. The filling pipe 12 penetrates to the bottom of the lid 10 and is a hole for filling with refractory particles, and the small holes 13 are small holes for letting out air in the pouring nozzle hole, which has an appropriate number of 4 to 6 penetrating to the bottom. It is a hole.

Such a lid 10 is fitted at a position close to the upper end of the upper nozzle brick 3 at the bottom of the ladle, as shown in the sectional view of the bottom when the ladle is overturned in FIG. Next, the refractory particle supply pipe 14 is connected to the filling pipe 12 of the lid 10 .
and communicates with a sand tank (not shown).
A compressed air pipe 1 is connected to the refractory particle supply pipe 14.
5 are connected to each other, and force-feed the refractory particles 7 in the direction of the lid 10 , through which the refractory particles 7 are filled into the pouring nozzle hole of the upper nozzle brick 3. At the same time, the air in the spout nozzle hole is released from the air vent hole 13. When filling is completed, the supply pipe 14 is pulled out.

Although it is possible to fill the ladle with refractory particles by allowing them to fall naturally while the ladle is in an upright position, this poses a safety problem and is laborious. When using the lid 10 used in the present invention, the refractory particles can be filled with compressed air while the ladle is turned over, so both the equipment and the operation are simple and safe. Furthermore, since the installation, parts replacement, adjustment, etc. of the flow rate control device are carried out with the ladle turned over as shown in FIG. 4, the above-mentioned filling operation can be carried out at the same time.

When using a molten metal container such as a ladle or tundish that has been fitted with the lid 10 and filled with the powder refractories 7 as described above, for example, in the case of a steelmaking ladle, first, before receiving the steel, The state is as shown in Fig. 5. When the molten steel 6 is then received, as shown in Fig. b, the molten steel partially enters the hole of the refractory particle filling pipe 12 of the lid 10 and the small air vent hole 13, and the upper The entire iron plate 11 and lid 10 are heated to a high temperature.
At this time, since the lid 10 contains a heat generating agent, the molten steel that has entered the hole does not solidify. Next, the lid 10 is carbonized in an air-deficient atmosphere, and becomes a weakened carbonized state as shown at 10 in Figure C. When the refractory particles 7 are dropped, the molten steel is forced into the lid 10 by the load as shown in Figure d. It breaks down the carbide and pours out smoothly.

As explained above, in this invention, a lid made of a material that is easily carbonized and equipped with a refractory particle filling hole and an air vent hole is fitted into the upper nozzle brick hole for pouring, and the refractory particles are filled and received. By using steel, the lid becomes carbonized and brittle due to heating, making it more likely to fall, allowing for an almost completely natural opening. Therefore, due to the strong bridge formation of the nozzle hole, there is no need to manually open the nozzle hole, and there is no need to interrupt the casting process, which greatly benefits the smooth operation of the steel factory. be. Furthermore, this opening method can be applied not only to the steel manufacturing industry but also to pouring containers for various types of molten non-ferrous metals.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of a part of the bottom of the molten metal container, Fig. 2 is an explanatory diagram showing the reaction situation between the refractory particles filled in the pouring nozzle hole at the bottom of the molten metal container and molten metal; FIG. 3 is a perspective view showing an embodiment of the lid used in this invention, and FIG. 4 is a longitudinal sectional side view of the bottom of a ladle showing an embodiment of this invention. FIG. 5 is an explanatory diagram showing the opening situation according to the method of this invention. In each figure, 3... Upper nozzle brick, 4... Flow rate control device, 6 ... Molten steel, 7... Powder refractory, 1
0...Lid, 12...Pipe for filling refractory particles, 1
3... Small hole for air vent, 14... Refractory particle supply pipe, 15... Compressed air pipe.

Claims (1)

[Claims] 1. When pouring molten metal from a molten metal container using a sliding nozzle flow rate control device, a hole for filling refractory particles and a small hole for venting air are provided at the upper end of the upper nozzle brick hole for pouring. After fitting a lid made of an easily carbonizable material of a mixture of cellulose, rubber, and/or exothermic agent, refractory particles are filled into the upper nozzle brick hole through the lid, and then molten metal is received and filled. A method for opening a spout hole for molten metal, characterized in that the spout hole is opened by allowing refractory particles to fall.