JPH032314A - Submerged tube for treating molten metal - Google Patents

Abstract

PURPOSE:To reduce repairing cost of a submerged tube and to lengthen the service life by packing refractory particles near a gas blowing hole and monolithic refractory the other part in gap between inner wall of a sleeve brick having a through hole and remaining refractory. CONSTITUTION:In a submerged tube 1 for treating molten metal with an iron shell 20 covered with the refractory which is arranged with at least one of gas blowing hole 2, the inner wall is formed with the sleeve brick 5 and the through hole 9 is bored at the position corresponding to the above gas blowing hole 2. In the gap between the remaining refractory 8 and the above sleeve brick 5 for this submerged tube 1, the refractory particles 11 are packed near the above gas blowing hole 2, and in the other part, the monolithic refractory 6 is packed. The above refractory particles 11 are made to about 3-5mm particle size to secure permeability of the blowing gas and prevent penetration of the monolithic refractory 6. By this method, the submerged tube 1 which is easily repaired, has a long service life and can surely executed gas blow treatment is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an immersion tube that is immersed in molten metal and used for depressurization treatment, gas blowing treatment, etc.

[Prior Art] Generally, most of the molten metal (hereinafter simply referred to as molten steel) refined in a converter, electric furnace, etc. is cast after undergoing secondary refining.

Typical examples of this secondary refining are DH or RH.
CAS, C such as degassing treatment method or Ar bubbling etc.
There are two AB methods, both of which use an immersion tube to process molten steel.

This secondary refining involves blowing inert gas or oxidizing gas into the molten steel through an immersion pipe in order to produce ultra-low carbon steel by promoting decarburization of the molten steel, or to achieve high purity by promoting the floating of inclusions. This approach has been adopted and has been highly effective.

However, in secondary refining, the injection of inert gas, etc. increases the load on refractories, which significantly shortens the life of immersion pipes, reduces processing capacity due to repairs and replacements, and increases processing costs. .

In addition, even if repairs are performed using monolithic refractories, the normal repair method will not be able to perform the gas injection function because the inert gas or oxidizing gas injection hole will be blocked or ventilation will be obstructed.
Moreover, obstruction of the ventilation gas passage conversely shortens the life of the refractories.

Therefore, as a method for repairing immersion pipes, for example, JP-A-57-5
As shown in Japanese Patent Publication No. 122, a method of pressing a gas blowing hole forming body from a core through a feeding mechanism, or a method of pressing the gas blowing hole forming body from a core through a feeding mechanism, or a method of
As shown in Publication No. 117210, gas injection is possible even after the lining has been repaired by covering the opening of the gas injection nozzle of the immersion pipe with an easily collapsible annular blocker and then lining it with monolithic refractory material. Repair methods have been proposed, and some have been put into practical use.

However, when repairing a immersion pipe, the method of securing gas injection holes by pressing an injection hole forming body and constructing monolithic refractories results in 10 to 20 gas injection holes. The mechanism of the pore former becomes complicated. Further, precision in pressing against the blow hole in the circumferential direction is required, and the equipment itself is expensive and has drawbacks such as being impractical. In addition, in the method of covering the opening of the gas injection nozzle with an easily collapsible plug and lining it with a monolithic refractory, the gas injection hole 2 of the immersion pipe 1 can be After filling the lower part with easily collapsible closing body 3, sleeve bricks 5 are disposed above the gas injection hole 2 through core 4, and monolithic refractory material 6 is poured. Therefore, there is only an easily collapsible blocker 3 below the gas injection hole 2, and no reliable refractory repair has been performed as shown in the right part of the figure. Therefore, although Ar gas or oxidizing gas can be blown in sufficiently, the lower part of the immersion tube cannot be repaired, so the lower part of the immersion tube reaches its lifespan, and as a result, a long life cannot be achieved.

In addition, a monolithic refractory 6 has been repaired above the gas injection hole 2.
The sleeve bricks 5 are not able to exhibit sufficient repair effects because they suffer preliminary erosion due to the attack of the blown gas and molten steel. Moreover, since a large amount of the easily collapsible blocker 3 filled below the gas injection hole 2 is consumed during repair, the repair cost is high compared to the service life.

[Problems to be Solved by the Invention] The present invention solves the drawbacks of these conventional repair methods, and the repair means and repair equipment are simple, and moreover, the original purpose of gas blowing processing can be performed. The present invention provides an immersion tube for molten metal processing, which also reduces repair costs and extends the life of the immersion tube.

[Means and effects for solving the problems] The present inventors have conducted various studies on regenerating and repairing immersion pipes that can ensure gas injection into the immersion pipes even after repair.

This led me to misunderstand the structure of the dip tube shown in FIG.

The immersion tube for treating molten steel shown in FIG. 1 will be explained below. In the figure, the immersion pipe 1 is formed by inserting a monolithic refractory 6 placed on the surface of a residual refractory 8 and a sleeve brick 5 which also serves as a pouring frame for the monolithic refractory 6.

Here, the sleeve brick 5 is provided with a through hole 9 at a position corresponding to the gas injection hole 2, and an overflow hole 10 for the monolithic refractory 6 is provided below the gas injection hole 2.

Further, the gap between the remaining refractory 8 and the sleeve brick 5 near the gas injection hole 2 is filled with highly heat-resistant refractory particles 11. The monolithic refractory 6 is, for example, MgO.

ZrO□l A Q203 g 5lot g Cr,
0. The refractory particles 11 are made of a refractory having corrosion resistance equal to or higher than these press-fit materials, and the press-fit materials are refractory particles. The particle size of the refractory particles is set to 3 mm to 5 mm in order to prevent the particles from penetrating into the packed layer 11 and to ensure ventilation from the gas injection holes 2. According to the knowledge of the present inventors, the refractory particles 11 are most preferably MgO particles.

This dip tube can be formed by the method shown in FIG.

In FIG. 2, a sleeve brick 5, a core 4 and a sealing device 12 are shown.
is placed on a traveling trolley (not shown). The core 4 is used for press-fitting the monolithic refractory 6 and is fixed on a traveling carriage. The sealing device 12 is used to seal the lower end 7 of the immersion pipe before press-fitting the monolithic refractory 6, and is mounted on a traveling carriage so as to be movable up and down by a hydraulic or electric mechanism.

The core 4 is provided with a lower press-fit pipe 14a and an upper press-fit pipe 14b connected to a monolithic refractory storage tank (not shown) for press-fitting the monolithic refractory 6. A hopper 15 for refractory particles 11 and an operator 16 for opening and closing the hopper are provided.

A catch seat 17 is disposed on the sealing device 12, and a sealing material 18 such as ceramic wool is spread over the catch seat 17.

When repairing or forming an immersion pipe, first, a sleeve brick 5 and a hopper 15 storing refractory particles 11 and an operator hand 16 are arranged in the core 4. Thereafter, the immersion tube 1 is positioned as shown in FIG. 2 by lowering the entire tank 19. This operation adjusts the positions of the throat part 13 and the top of the sleeve brick 5, and at the same time
and the through-hole 9 of the sleeve brick are also positioned and adjusted. The position of the top of the sleeve brick 5 is set to a height that allows sufficient repair of the throat portion 13. By sufficiently repairing the throat portion 13, the life of the tank 19 will be extended, and the monolithic refractories on the inner surface of the immersion tube 1 will also be protected, improving the effectiveness of repairing the immersion tube. Next, the lower end 7 of the immersion tube 1 is sealed by the sealing material 18 spread on the seat 17 by raising the sealing device 12 .

In this state, the monolithic refractory 6 is press-fitted from the lower press-fit pipe 14a. When the filling amount of the monolithic refractory 6 reaches the height of the overflow hole 10 by press-fitting, the monolithic refractory 6 flows out from the overflow hole 10, so after confirming this, the press-fitting is interrupted.

Next, the hopper 15 for the refractory particles 11 is opened by pushing up the operator hand 16, and the stored refractory particles 11 are dropped into the gap between the remaining refractory 8 and the sleeve brick 5. A packed layer of refractory particles 11 is formed by this dropping. This packed layer is formed from the overflow hole 10 to slightly above the gas blowing hole 2. After forming the packed layer of refractory particles 11, the monolithic refractory 6 is press-fitted from the upper press-in pipe 14b, and the remaining gap is filled with the monolithic refractory 6 to complete the lining and repair.

[Example] The immersion tube shown in FIG. 1 was used in a 350 ton/ch DH type degassing apparatus. Further, as a comparative example, the immersion tube shown in FIG. 3 was used. The thickness of the sleeve brick for both immersion pipes is 70 mm.
Mg0-Cr, O, type material, monolithic refractory is tQ
, 03 series material was used.

In addition, in Figure 1, the refractory particles have a size of 3 mm to 5 mm.
gO particles were used.

As a result 1, the dip tube of the present invention shown in FIG.
．． The service life was extended three times, and at the same time, the Ar gas blowing characteristics were also extremely good.

[Effects of the Invention] As described above, by using the immersion tube of the present invention, the originally intended purpose of blowing gas such as Ar can be performed with a simple structure of the immersion tube, and the life of the immersion tube can be extended. be able to. The dip tube of the present invention is also easy to repair.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an example of the dip tube of the present invention, and FIG.
FIG. 3 is a diagram showing the state of repair of the immersion pipe shown in FIG. 3, and FIG. 3 is an example of a cross section of a conventional repaired immersion pipe. 1: Immersion pipe, 2: Gas injection hole, 5 Nisleeve brick, 6: Monolithic refractory, 8: Residual refractory. 9: through hole, 10 nitrogen flow hole, 11: refractory particles, 20 iron skin. Figure 2 Patent applicant Nippon Steel Corporation

Claims (1)

[Claims] In an immersion pipe whose iron shell is covered with a refractory material and has at least one gas injection hole inside, the inner wall of the immersion pipe is formed of a sleeve brick having a through hole at a position corresponding to the gas injection hole, and the remaining For molten metal processing, the gap between the refractory and the sleeve brick is filled with refractory particles in the vicinity of the gas injection hole, and filled with monolithic refractory in areas other than the vicinity of the gas injection hole. dip tube.