JPH09256030A - Method for preventing sticking of skull to vacuum degassing vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preventing method of the sticking of skull to a vacuum degassing vessel capable of restraining noise due to the combustion and also reducing loss due to the removal of the skull by uniformly heating the inside of the vacuum degassing vessel. SOLUTION: The method to prevent the sticking of skull to the vacuum degassing vessel is to prevent the sticking of solidified skull to the inner wall of the vacuum degassing vessel 11 by executing the vacuum refining of molten steel 18 sucked into the vacuum degassing vessel 11 through immersion tubes 13, 14 arranged at the lower part of the vacuum degassing vessel 11, after preheating the vacuum degassing vessel 11 with a burner 12 arranged at the upper part of the vacuum degassing vessel 11. In this case, the lower end parts of the immersion tubes 13, 14 are closed to preheat the vacuum degassing vessel 11 with the burner 12.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a DH (Dortmu)
nd Holder), RH (Ruhrstahl H
eraus) and a vacuum degassing tank used for vacuum treatment, etc. having a straight body type immersion pipe, a preheating method, or a vacuum degassing tank for dissolving and removing metal and slag adhering to the refractory of the vacuum degassing tank. The present invention relates to a method of preventing adhesion of metal.

[0002]

2. Description of the Related Art Vacuum refining treatment by DH, RH, etc. is carried out, for example, in RH by dipping a refractory material called a reflux pipe (upcomer pipe, downcomer pipe), a suction pipe, etc. provided at the bottom of a vacuum degassing tank. As shown in FIG.
The molten steel 18 is immersed in the molten steel 18 and the vacuum degassing tank 11 is depressurized to suck the molten steel 18 into the vacuum degassing tank 11, and oxygen is blown into the molten steel 18 under reduced pressure to carry out the refining reaction. Vacuum refining treatment is carried out to accelerate and further adjust necessary components. During the vacuum refining process, oxygen is blown to the surface of the molten steel, and the molten steel is vigorously agitated by the refining reaction inside the molten steel, so molten steel accompanying splash, slag, and other droplets adhere to the refractory wall,
As shown in FIG. 15, the molten steel is vacuum degassed after the vacuum refining 1
When discharged from No. 1, molten steel solidifies on the inner walls of the dip pipes 13 and 14, and the metal 57 or slag adheres. The lower the surface temperature of the vacuum degassing tank 11, the larger the amount of the bare metal 57 or slag attached tends to be. Also,
If the bare metal 57 is left attached, the oxygen blowing lance used during vacuum refining cannot be moved up or down, or the exhaust gas duct is blocked, which interferes with the subsequent vacuum refining operation. Occurs. Therefore, preheating for suppressing the adhered metal and clean heating for melting and removing the adhered metal are required.

For example, Japanese Patent Publication No. 3-71484 discloses a vacuum degassing tank 11 as shown in FIGS.
The burner 12 is inserted in the top of the vacuum degassing tank 11, the fuel supplied to the burner 12 is burned in the vacuum degassing tank 11, and the combustion gas is provided in the exhaust port 16 and the lower part provided on the upper side surface of the vacuum degassing tank 11. The heating method of the vacuum degassing tank 11 which is distributed to both of the immersion pipes 13 and 14 and discharged to the outside is described. This is the immersion pipe 13 in the molten steel 18 of the molten steel container 17,
In a state before dipping 14 or in a state in which the dipping pipes 13 and 14 are pulled up from the molten steel 18 after completion of vacuum refining, the refractory in the vacuum degassing tank 11 is heated by using a burner 12 to perform vacuum degassing. It is intended to preheat the refractory material in the tank 11 and to dissolve and remove the base metal 57 adhering to the refractory material wall.

[0004]

However, the heating method for the vacuum degassing tank described in Japanese Patent Publication No. 3-71484 has the following problems. The flame generated by the burner 12 causes the immersion pipes 13 and 14 to
In addition, the temperature difference in the length direction of the flame becomes large because it is caused to flow toward the exhaust port 16, and it is difficult to uniformly heat the vacuum degassing tank 11. In particular, since it is difficult for the temperature of the ceiling corners and the like to rise, the removal of the metal 57 or slag adhered to the corners is hindered. Since the temperature difference in the vacuum degassing tank 11 is large and the refractory in the portion in contact with the flame is locally heated, the thermal shock load due to such temperature difference becomes excessive and the refractory is damaged. The tendency increases. Since the lower ends of the immersion pipes 13 and 14 are open to the outside air, noise caused by the combustion of the burner 12 causes
The work environment may be impaired by leaking to the outside through the lower end of 14. In order to process the molten metal, as shown in FIG. 15, it is necessary to prepare a slag pan 56 and the like below the dipping pipes 13 and 14, and the metal 57 itself becomes a loss and the production yield is reduced. It leads to a decrease and wastes energy. The present invention has been made in view of the above circumstances, and uniformly heats the inside of a vacuum degassing tank to suppress the adhesion of metal in the tank, preheat, and heat for metal removal ( Clean heating)
It is an object of the present invention to provide a method for preventing the adhesion of metal in a vacuum degassing tank, which can efficiently perform the above-mentioned process to reduce the loss due to the adhesion of metal and also reduce the noise during burner combustion.

[0005]

According to the present invention, there is provided a semiconductor device comprising:
The method for preventing the adhesion of metal to a vacuum degassing tank is described in the following: after preheating the vacuum degassing tank with a burner provided at the upper part of the vacuum degassing tank, a dip tube provided at the bottom of the vacuum degassing tank. In a method for preventing adhesion of metal in a vacuum degassing tank, which performs vacuum refining of molten steel sucked into the vacuum degassing tank through the metal and prevents adhesion of metal that adheres to the inner wall of the vacuum degassing tank and solidifies. The lower end of the dip tube is closed and the burner preheats the vacuum degassing tank. The method for preventing adhesion of metal in a vacuum degassing tank according to claim 2, wherein molten steel held in a molten steel container arranged below the vacuum degassing tank is replaced by a dip pipe provided at a lower portion of the vacuum degassing tank. After performing vacuum refining by sucking into the vacuum degassing tank via the above, the inside of the vacuum degassing tank is cleanly heated by a burner provided on the upper part of the vacuum degassing tank, In the method of preventing adhesion of metal in a vacuum degassing tank, which melts and removes the metal that adheres to the inner wall, and slag, the lower end of the immersion pipe is immersed in molten steel in the molten steel container, and vacuum degassing is performed by the burner. Clean and heat the bath. The method of preventing adhesion of metal to a vacuum degassing tank according to claim 3, wherein a lower end of an immersion pipe provided at a lower portion of the vacuum degassing tank is closed and a burner is provided at an upper portion of the vacuum degassing tank. After preheating the vacuum degassing tank and performing vacuum refining of the molten steel, the lower end of the immersion pipe is immersed in the molten steel in the molten steel container, and attached to the inner wall of the vacuum degassing tank using the burner. Dissolve and remove ingots and slag.

The vacuum degassing tank is a container for holding molten steel lined with a refractory, and under a reduced pressure, oxygen gas or an inert gas is blown into the molten steel to be held to carry out a necessary refining reaction. It refers to a reaction vessel of a refining device such as DH, RH, and a straight body type that can be used. The immersion pipe provided at the bottom of the vacuum degassing tank is a pipe lined with a refractory that is immersed in the molten steel in the molten steel container to suck up, discharge, or circulate the molten steel. Includes pipes, the lower part of a straight-body type vacuum tank (near the immersion part), and the like. Closing the lower end of the immersion pipe can be performed by immersing the lower end of the immersion pipe in the molten steel or slag in the molten steel container to shut off the outside air from the inside of the immersion pipe. Alternatively, a stopper member for sealing the lower end of the dip tube may be brought into contact with and pressed against the lower end of the dip tube. The molten steel container refers to a container lined with a refractory material that holds molten steel adjusted to necessary components in a converter or the like. Burners are LPG, blast furnace gas, C
It is a combustion device that burns a fuel gas such as O 2 gas and an oxygen gas, and can be substituted by an oxygen gas blowing lance in the vacuum refining process. In addition to the above fuel gas and oxygen gas, an inert gas such as argon gas may be mixed to control the combustion reaction.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, referring to the attached drawings, an embodiment in which the present invention is embodied will be described to provide an understanding of the present invention. FIG. 1 is an explanatory diagram of a vacuum refining device 10 to which a method for preventing metal adhesion in a vacuum degassing tank according to an embodiment of the present invention is applied. As shown in FIG. 1, the vacuum refining apparatus 10 includes a vacuum degassing tank 11, an immersion pipe 13 (upcomer pipe), an immersion pipe 14 (downcomer pipe), and an immersion pipe 13, which are provided below the vacuum degassing tank 11. 14 and a molten steel container 17 arranged below. A burner 12 for heating the inside of the vacuum degassing tank 11 is arranged at the top of the vacuum degassing tank 11, and a side wall of the vacuum degassing tank 11 is provided with a vacuum pump such as a steam ejector (not shown). An exhaust port 16 for reducing the pressure inside the vacuum degassing tank 11 is provided. The inside of the vacuum degassing tank 11 is lined with a fired refractory made of magnesia chromia (magchrome), and the inner parts of the dipping pipes 13 and 14 are made of alumina and alumina-silica fired refractories, and the outer part thereof. Has a structure constructed with high-alumina castable and other irregular refractory materials.

At the lower part of the vacuum degassing tank 11, there are provided a rising pipe 13 for further moving the sucked molten steel 18 and a descending pipe 14 for lowering the vacuum degassing tank 11. There is. The rising pipe 13 is provided with an inert gas supply portion (not shown) for circulating and moving the molten steel 18. By supplying the inert gas to the rising pipe 13, the rising motion of the inert gas is accompanied. The molten steel 18 in the rising pipe 13 moves upward, and the molten steel 18 descends from the descending pipe 14 toward the molten steel container 17. Therefore, the vacuum degassing tank 11
When performing the vacuum refining process inside, the molten steel 18 in the molten steel container 17 is circulated in the vacuum degassing tank 11 so that the molten steel 18 can be refined until a necessary amount of components is obtained. The molten steel container 17 is a steel container lined with a refractory material such as alumina-silica or high-alumina, and is a molten steel 18 such as stainless steel or aluminum-killed steel refined in a converter.
Is held for about 300t. In addition, an elevation moving device (not shown) is provided to control the relative position between the vacuum degassing tank 11 and the molten steel container 17, and the dip tube 1 is provided as necessary.
The lower end portions 15 of 3 and 14 can be immersed in the molten steel 18 of the molten steel container 17 or pulled up.

Next, a method of preventing the adhesion of metal to the vacuum degassing tank according to the first embodiment of the present invention using the above-described vacuum refining apparatus 10 will be described in detail. Here, FIG.
FIG. 2A is an explanatory diagram of a pattern showing a procedure of a method of preventing metal adhesion in the vacuum degassing tank according to the first embodiment, and FIG.
(D) is explanatory drawing of the pattern of the heating method in a prior art example. The following description will be made with reference to these. First, the dipping pipes (the ascending pipe 13 and the descending pipe 14) of the vacuum degassing tank 11 are dipped in the molten steel 18 in the molten steel container 17, and after that, FIG.
The immersion period shown in (a) is reached. In addition, the immersion pipes 13 and 14
Prior to immersing the lower end 15 of the molten steel 18 in the molten steel 18 of the molten steel container 17, only the lower end 15 of the immersion pipes 13 and 14 is partially preheated, so that the thermal shock of the refractory It is possible to reduce the load of and to suppress damage due to thermal spalling. And the dip tube 13,
In the state where the lower end portion 15 of 14 is immersed in the molten steel 18, the steam ejector is driven to move the inside of the vacuum degassing tank 11 to 30
Depressurize to a vacuum of 0 torr. Then, LPG (liquefied propane gas) is blown into the vacuum degassing tank 11 using the burner 12 in an amount of 100 Nm ³ / hr and 90% of the theoretical oxygen amount to burn the vacuum degassing. Preheating of the tank 11 was started (FIG. 3). This time,
The distance from the tip of the burner 12 to the surface of the molten steel 18 was set to about 2 m.

Thereafter, such combustion is performed until a predetermined preheating time is reached. During such preheating, combustion gas is not discharged from the lower end portions 15 of the dip tubes 13 and 14, so that the flame diffuses in the vacuum degassing tank 11,
The temperature difference in the vertical direction in the vacuum degassing tank 11 is made uniform, and the interior of the vacuum degassing tank 11 can be efficiently heated. By the way, in the preheating method in the conventional example shown in FIG. 14, the flame of the burner 12 causes the immersion pipe 13,
It becomes a long flame by being pulled in the direction of 14, and the vacuum degassing tank 1
The variation in the temperature distribution in the vertical direction in 1 becomes large, and uniform heating is difficult. Further, it is possible to suppress the noise generated when the burner 12 burns from leaking to the outside.
During this preheating, the exhaust port 16 connected to the water vapor ejector is sealed so that the vacuum degassing tank 11 can be preheated through another exhaust system. After heating the inside of the vacuum degassing tank 11 in this way so as to have a sufficiently uniform temperature distribution, the vacuum degassing tank 11 is driven by driving the steam ejector.
The inside is further depressurized, and the degree of vacuum in the molten steel container 17 is adjusted to a required level through the dipping pipes 13 and 14.

Then, an inert gas is blown from an inert gas supply section provided in the rising pipe 13 to circulate the molten steel 18, and a lance for blowing oxygen gas or the like provided at the top of the vacuum degassing tank 11. Oxygen gas, argon gas, or the like is sprayed onto the surface of the molten steel 18 via 20 to perform necessary vacuum refining under reduced pressure (FIG. 4). The burner 12 for combustion and the blowing lance 20 may have the same structure and may be shared. At this time,
The molten steel 18 in the vacuum degassing tank 11 is vigorously stirred, and splashes of the molten steel 18 accompanying this splash are generated in the vacuum degassing tank 11
The metal adheres to the side wall or ceiling of the and solidifies to cause metal adhesion. Then, after completing the vacuum refining process such as component adjustment, the output of the steam ejector is stopped, and the immersion pipes 13 and 14 are pulled up from the molten steel 18 surface of the molten steel container 17 to remove the molten steel 18 in the vacuum degassing tank 11.
Is returned to the molten steel container 17. Then, the metal 19 or slag adhering to the vacuum degassing tank 11 after discharging the molten steel 18 is melted using the burner 12, and the melted metal 19 or slag is discharged to a slag pan or the like to make a series. Ends the process.

FIG. 5 is a graph showing the relationship between the preheating time per vacuum refining treatment and the surface temperature in the vacuum degassing tank 11 at that time. The surface temperature in the vacuum degassing tank 11 in the figure is obtained by measuring the temperature of the refractory surface at several points and displaying the average value.
Plots marked with Δ show the results of the preheating in the present embodiment, and marks marked with ◯ show the results of the conventional example in which the preheating is performed without immersing the dipping pipes 13 and 14 in the molten steel 18.
Further, FIG. 6 is a graph showing the relationship between the preheating time and the amount of metal adhered after the completion of vacuum refining. The plot of Δ shows the result in the present embodiment, and the ○ mark shows the result in the conventional example. There is. For example, when the preheating time is set to 30 minutes per vacuum refining process, the surface temperature in the vacuum degassing tank 11 in the present embodiment is about 30 as compared with the conventional example.
The temperature is 1400 ° C., which is 0 ° C. higher, and the amount of bare metal adhered under such temperature conditions is 0.2 T / ch, which is about 0.6 T / ch less than the conventional example. As is clear from FIGS. 5 and 6, by setting the preheating time to 20 minutes or longer, it is possible to reduce the amount of metal adhered to a level of about 1/2 or less of that of the conventional example. It can be seen that troubles such as poor lifting and lowering are avoided and stable operation of the vacuum refining process is possible.

Next, a method for preventing metal adhesion in a vacuum degassing tank according to a second embodiment of the present invention using the above-described vacuum refining apparatus 10 will be described in detail. Here, FIG.
(B) is an explanatory view of a method of preventing metal adhesion in the vacuum degassing tank according to the second embodiment, and the following description will be made with reference to this. First, as shown in FIG.
After heating the vacuum degassing tank 11 and the dipping pipes 13 and 14 to a required temperature in advance with the lower end portion 15 of the vacuum degassing tank 11 open, the dipping pipes (the ascending pipe 13, the descending pipe) of the vacuum degassing tank 11 are heated. 14) is immersed in the molten steel 18 in the molten steel container 17, and the subsequent period is the immersion period.

Then, the steam ejector is driven to reduce the pressure in the vacuum degassing tank 11 via the exhaust port 16, and the molten steel 18 in the molten steel container 17 is placed in the vacuum degassing tank 11 via the dipping pipes 13 and 14. Aspirate into. Then, an inert gas is blown from a not-shown inert gas supply unit provided in the rising pipe 13 to circulate the molten steel 18, and as shown in FIG. 4, a blower provided at the top of the vacuum degassing tank 11 is blown. Oxygen gas, argon gas, or the like is sprayed onto the surface of the molten steel 18 through the lance 20 to perform the necessary vacuum refining treatment under reduced pressure. At this time, the molten steel 18 in the vacuum degassing tank 11 is vigorously agitated, and the splash of the molten steel 18 accompanying the splash adheres to the side wall or the ceiling of the vacuum degassing tank 11 and solidifies the solid metal 19 Adherence occurs.

Then, the vacuum refining process such as the component adjustment is completed, and as shown in FIG.
As a reduced pressure state of torr, LPG (liquefied propane gas) 180 Nm ³ / hr, and oxygen gas are blown into the vacuum degassing tank 11 using the burner 12 and burned to cause the ingot to adhere to the vacuum degassing tank 11. 19. Clean heating for melting and removing slag was started. The clean heating in the sealed state under reduced pressure not only makes the flame uniform, but also improves the heating efficiency, and the vacuum degassing tank 1
The surface temperature of No. 1 increases, and the adhered metal 19 or slag can be melted efficiently and economically. In this cleaning and heating, the vacuum degree of the vacuum degassing tank 11 is lowered to lower the level of the molten steel 18 as shown in FIG.
It is also possible to effectively heat the inside of 3, 14.
The metal 19 melted in this way travels along the refractory surface of the vacuum degassing tank 11 and is recovered in the molten steel 18 of the molten steel container 17 through the dip pipes 13 and 14, so that the yield of the molten steel 18 is increased. It does not lower. And finally, dip tube 13,
14 is pulled up from the molten steel surface of the molten steel container 17, and the molten steel 18 in the vacuum degassing tank 11 is returned to the molten steel container 17.

9 and 10, such cleaning heating is performed for a predetermined cleaning heating time (melt flow time), and the surface temperature in the vacuum degassing tank 11 at this time is melted by this cleaning heating. The relationship with the melt flow rate of the base metal 19 is obtained respectively. Here, the surface temperature in the vacuum degassing tank 11 in the figure is obtained by measuring the temperature of the refractory surface at several points and displaying it by the average value. Also, the plots marked with Δ indicate clean heating (see FIG. The result of applying 7) is the dip tube 13,
14 is heated in molten steel 18 without being immersed,
The result of the conventional example (FIG. 15 and FIG. 2 (d)) which melt | dissolves is shown. For example, when the cleaning and heating time is set to 20 minutes per vacuum refining process, the surface temperature in the vacuum degassing tank 11 in this embodiment is about 30 as compared with the conventional example.
The temperature is 1500 ° C., which is higher by 0 ° C., and the melting flow rate of the metal 19 melted under such a temperature condition is about 0.2 as compared with the conventional example.
The number of T / ch is increased to 0.5 T / ch. As is clear from FIGS. 9 and 10, by setting the cleaning and heating time to 20 minutes or more, the melt flow rate of the base metal 19 can be increased to about twice that of the conventional example. Can suppress the loss of.

Next, a method of preventing metal adhesion in a vacuum degassing tank according to a third embodiment of the present invention using the above-described vacuum refining apparatus 10 will be described in detail. Here, FIG.
(C) is an explanatory view of a method of preventing metal adhesion in the vacuum degassing tank according to the third embodiment, and the following description will be made with reference to this. First, only the lower end portions 15 of the immersion pipes 13 and 14 are partially preheated, and then the immersion pipes (the rising pipe 13 and the descending pipe 14) of the vacuum degassing tank 11 are connected to the molten steel 1 in the molten steel container 17.
Immerse in 8. Then, the lower end portion 1 of the immersion pipes 13 and 14
LPG (liquefied propane gas) was 180 Nm ³ / h in a state where 5 was immersed in molten steel 18, that is, in a state where the lower end 15 side of the immersion pipes 13 and 14 of the vacuum degassing tank 11 was sealed.
r and oxygen gas were blown into the vacuum degassing tank 11 by using the burner 12 in an amount of 90% of the theoretical oxygen amount to burn, and preheating of the vacuum degassing tank 11 was started as shown in FIG. .

In this way, after preheating the inside of the vacuum degassing tank 11 so as to have a sufficiently uniform temperature distribution, as shown in FIG. 4, a blowing lance provided on the top of the vacuum degassing tank 11. Oxygen gas, argon gas, or the like is sprayed onto the surface of the molten steel 18 via 20 to perform a necessary vacuum refining process.

Then, the vacuum refining process such as component adjustment is completed, the inside of the vacuum degassing tank 11 is depressurized to about 200 torr, and the burner 12 is used to heat the vacuum degassing tank 11 as shown in FIG. Metal 1 that starts heating and adheres
9 was dissolved. By the clean heating in the closed state under reduced pressure, the flame is made uniform, the heating efficiency is increased, the surface temperature of the vacuum degassing tank 11 is increased, and the adhered metal 19 is efficiently dissolved. Can be done economically. Moreover, since the molten metal 19 is collected in the molten steel 18 of the molten steel container 17 along the refractory surface of the vacuum degassing tank 11, the yield of the molten steel 18 is not reduced. Finally, the immersion pipes 13 and 14 are connected to the molten steel 18 of the molten steel container 17.
The operation of pulling up from the surface and returning the molten steel 18 in the vacuum degassing tank 11 to the molten steel container 17 is performed. By thus performing the above-mentioned preliminary heating and clean heating before and after the vacuum refining treatment, adhesion of the metal 19 during the vacuum refining treatment is suppressed,
In addition, by effectively melting and collecting the ingots 19 attached, it is possible to prevent the loss of the molten steel 18 due to the attachment of the ingots 19.

Next, as a fourth embodiment of the present invention,
When performing decarburization under a reduced pressure using a vacuum refining device 30 having a large diameter straight-body type vacuum degassing tank 31 having a dip pipe 33 of the same diameter as shown in FIG. 12 different from RH Will be described. Here, the vacuum degassing tank 31 is blown by the burner 32 while depressurizing the inside of the dipping pipe 33 with the molten steel 18 of the molten steel container 17 or the slag of the upper layer with the ejector using the ejector while depressurizing the inside of the tank. Heat for a predetermined time before starting acid refining. As a result, the distribution of the refractory surface temperature along the height direction of the straight body part, as shown by the distribution of the circles in the shaded area in FIG. 13, is such that the surface temperature of the vacuum degassing tank 31 is substantially uniform and required. It is also possible to selectively heat the metal adhesion site according to the above. The symbol Δ indicates the state of the refractory surface temperature when such preheating is not performed. As a result, it is possible to significantly suppress the adhesion of the metal in the tank itself due to the radical splash at the time of decarburization of blown acid under reduced pressure. Further, even in the clean heating in the component adjusting step after the decarburization by blowing acid, the melt flow rate of the base metal 19 could be greatly improved to about twice.

The embodiment of the present invention has been described above.
The present invention is not limited to these embodiments, and all changes in conditions without departing from the gist are within the scope of the present invention. For example, in the present embodiment, the case of application to the RH-type vacuum refining apparatus has been described, but the application to the DH-type vacuum refining apparatus in which the dip tube is only the suction tube is also possible. Further, a heating method in which the vacuum degassing tank is sealed without depressurizing the preheating or cleaning heating is also within the scope of the present invention.

[0022]

In the method of preventing adhesion of metal in a vacuum degassing tank according to the first aspect of the present invention, since the lower end of the immersion pipe is closed and the vacuum degassing tank is preheated by a burner, the flame of the burner, and The combustion gas does not leak to the outside through the lower end portion of the dip tube, the inside of the vacuum degassing tank can be uniformly and efficiently heated, and the noise due to burner combustion can be prevented from leaking to the outside. And because vacuum refining is performed in a vacuum degassing tank that is heated uniformly and at high temperature, even if molten steel droplets due to the splash during vacuum refining adhere to the vacuum degassing tank, they do not solidify but drop and adhere to the base metal. The amount can be reduced. Further, in the method for preventing adhesion of metal in a vacuum degassing tank according to claim 2, after vacuum refining, the immersion pipe is vacuum degassed using a burner in a sealed state in which the immersion pipe is immersed in the molten steel in the molten steel container. Since the inside of the vacuum degassing tank is heated cleanly, the inside of the vacuum degassing tank can be heated uniformly and at a high temperature, and the metal and slag attached to the ceiling or the upper corner of the vacuum degassing tank can be reliably melted. At the same time, noise during burner combustion does not leak outside. Then, the metal or slag that adheres to the vacuum degassing tank can be efficiently melted, and the melted metal can be collected in the molten steel container, and the decrease in molten steel yield due to the adhesion of the metal can be prevented. it can.

In the method of preventing adhesion of metal in a vacuum degassing tank according to a third aspect, the burner is burned to preheat the vacuum degassing tank in a state where the tip of the dipping tube is closed.
It is possible to perform vacuum refining by sucking molten steel into a vacuum degassing tank that is uniform and heated to a high temperature, and even if droplets of molten steel due to splash during vacuum refining adhere to the vacuum degassing tank,
The amount of bare metal can be reduced by dropping without solidifying. Then, the vacuum degassing tank is heated using the burner while the immersion pipe is immersed in the molten steel in the molten steel container, so that the metal or slag adhered to the vacuum degassing tank is efficiently dissolved and removed, The molten metal can be collected in the molten steel container, the decrease in molten steel yield due to the adhesion of the metal can be prevented, and the noise level during burner combustion can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a vacuum refining device to which a method of preventing metal adhesion in a vacuum degassing tank according to an embodiment of the present invention is applied.

2 (a), (b), (c), and (d) are respectively the method for preventing adhesion of metal in a vacuum degassing tank according to the first, second, and third embodiments, and a conventional example. It is explanatory drawing of a procedure.

FIG. 3 is an explanatory diagram of a vacuum refining device to which the method for preventing metal adhesion in a vacuum degassing tank according to the first embodiment of the present invention is applied.

FIG. 4 is an explanatory diagram of a vacuum refining device during vacuum refining.

FIG. 5 is a graph showing the relationship between the preheating time per vacuum refining treatment and the surface temperature in the vacuum degassing tank.

FIG. 6 is a graph showing the relationship between the preheating time and the amount of metal adhered after the completion of vacuum refining.

FIG. 7 is an explanatory diagram of cleaning and heating in a vacuum refining apparatus to which the method for preventing metal adhesion in a vacuum degassing tank according to the second and third embodiments of the present invention is applied.

FIG. 8 is an explanatory diagram of clean heating in the method of preventing adhesion of metal in a vacuum degassing tank.

FIG. 9 is a graph showing the relationship between the clean heating time (melt flow time) and the surface temperature in the vacuum degassing tank.

FIG. 10 is a graph showing the relationship between the clean heating time (melt flow time) and the melt flow rate of the metal that is melted by the clean heat.

FIG. 11 is an explanatory diagram of preheating in a vacuum refining apparatus to which a method for preventing metal adhesion in a vacuum degassing tank according to a third embodiment of the present invention is applied.

FIG. 12 is an explanatory diagram of cleaning and heating in a vacuum refining device to which a method for preventing metal adhesion of a vacuum degassing tank according to a fourth embodiment of the present invention is applied.

FIG. 13 is a distribution diagram of the height of the straight body part and the refractory surface temperature in the straight body type vacuum refining furnace.

FIG. 14 is an explanatory diagram of a method for preheating a vacuum degassing tank according to a conventional example.

FIG. 15 is an explanatory diagram of a method for cleaning and heating a vacuum degassing tank according to a conventional example.

[Explanation of symbols]

10 Vacuum Refining Equipment 11 Vacuum Degassing Tank 12 Burner 13 Ascending Pipe (Immersion Pipe) 14 Downcomer Pipe (Immersion Pipe) 15 Lower End 16 Exhaust Port 17 Molten Steel Container 18 Molten Steel 19 Bare Metal 20 Blowing Lance 30 Vacuum Refining Equipment 31 Vacuum Degassing Gas tank 32 Burner 33 Immersion pipe 34 Exhaust port

Claims (3)

[Claims] 1. The vacuum degassing tank is preheated by a burner provided at the upper part of the vacuum degassing tank, and then the vacuum degassing tank is supplied to the vacuum degassing tank through an immersion pipe provided at the lower part of the vacuum degassing tank. In a method of preventing adhesion of metal in a vacuum degassing tank, which performs vacuum refining of molten steel to be sucked and adheres to an inner wall of the vacuum degassing tank to prevent solidification of solidified metal, a lower end portion of the immersion pipe is closed. And then preheating the vacuum degassing tank with the burner. 2. The molten steel held in a molten steel container arranged below the vacuum degassing tank is sucked into the vacuum degassing tank through a dip pipe provided at the bottom of the vacuum degassing tank. After performing vacuum refining, the inside of the vacuum degassing tank is cleanly heated by a burner provided at the upper portion of the vacuum degassing tank, and the metal and slag adhered to the inner wall of the vacuum degassing tank are melted, In the method for preventing adhesion of metal in a vacuum degassing tank for removing, the lower end of the immersion pipe is immersed in molten steel in the molten steel container, and the vacuum degassing tank is cleanly heated by the burner. How to prevent metal adhesion in gas tanks. 3. A vacuum for molten steel is obtained by pre-heating the vacuum degassing tank with a burner provided at the upper part of the vacuum degassing tank by closing the lower end of the dip tube provided at the lower part of the vacuum degassing tank. After performing refining, while the lower end of the immersion pipe is immersed in the molten steel in the molten steel container, the burner is used to melt and remove the metal and slag attached to the inner wall of the vacuum degassing tank. A method for preventing adhesion of metal in a vacuum degassing tank, characterized by: