JP2000328135A - Hot repair method of snorkel for vacuum degassing equipment and repair refractory used for this method - Google Patents

Abstract

(57) [Summary] To provide a hot repair of a snorkel for a vacuum degassing device quickly and reliably. The inner peripheral surfaces of the reflux pipe and the immersion pipe are overhauled by a boring bit. The repair refractory 6 having the joint material 8 integrally provided on the outer periphery is inserted into the overhauled hole. The joint material 8 uses pitch or thermoplastic synthetic resin as a binding material. When the repair refractory 6 is inserted into the hole of the snorkel 1, the joint material 8 is carbon-bonded by the residual heat of the furnace, and the repair fire refractory. The object 6 is fixed to the inner peripheral surface of the snorkel 1. Since the joint material 8 is non-aqueous, it cures quickly and can be repaired quickly.
Since the infiltration of air from the location (1) is blocked by the refractory for repair 6, the nitrogen pitch-up phenomenon can be prevented and the quality of molten steel can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for quickly and reliably performing hot repair of a snorkel for a vacuum degassing device,
It relates to repair refractories used for it.

[0002]

2. Description of the Related Art A vacuum degassing apparatus such as an RH type or DH type used for cleaning molten steel and adjusting components has a snorkel for introducing or discharging molten steel in a ladle to / from a vacuum tank. . The vacuum degassing apparatus is entirely lined with refractories, but the snorkel has a particularly high wear rate of refractories compared to other parts due to the flow of molten steel. Therefore, repair of refractories lined with snorkels has been performed.

In this case, in order to improve the operation rate of the vacuum degassing device, the repair of the snorkel is generally performed hot after the vacuum degassing device is stopped without waiting for the refractory lining to cool down.

As one of the repair methods, a method of inserting a core into a snorkel and filling an irregular-shaped refractory between the snorkel and the core by pouring, pouring or press-fitting is disclosed in Japanese Patent Laid-Open No. 50-8702. Gazette, Japanese Utility Model Publication No. 53-47046)
There is.

Also, a method of cutting and smoothing the inner hole surface (inner peripheral surface) of a snorkel in advance, and then inserting and fixing a sleeve-like refractory as a repair material (Japanese Patent Laid-Open No. Hei 8-60230).
There is. This method is excellent in durability after repair since the repair refractory is a fixed refractory.

[0006]

In the hot repair of a snorkel, a repair method using an irregular refractory as a repair refractory has a sufficient filling property so that the repair refractory can be filled at the repair site. Can not be obtained. In addition, it takes a considerable amount of time to dry the refractory for repair after construction, and rapid repair cannot be performed.

On the other hand, in a repair method of inserting a sleeve-like refractory into a snorkel, conventionally, mortar is applied to an outer peripheral surface of the sleeve-like refractory in order to fix the sleeve-like refractory to a portion to be repaired. But with this method,
It is said that the adhesiveness is low due to insufficient filling (fluidity) of the mortar, and that the mortar contains a large amount of water, so it takes time to dry the mortar, and stable and quick repair cannot be performed. There's a problem.

In the operation of the vacuum degassing apparatus, there is a problem of a so-called nitrogen pickup which causes air to enter the molten steel and contaminate the molten steel. In the conventional repair method, the effect of preventing nitrogen pickup was insufficient.

An object of the present invention is to solve the above-mentioned conventional problems in a hot repair method for a snorkel for a vacuum degassing apparatus.

[0010]

A feature of the present invention is that a snorkel for a vacuum degassing device is provided in which a sleeve-shaped refractory is inserted and fixed after cutting the inner surface of a snorkel with a dip tube attached to a reflux tube. In the hot repair method of (1), a joint material in which pitch and / or a thermoplastic resin is added as a binder to the refractory aggregate is previously provided on the outer surface of the sleeve-like refractory.

In the method of the present invention, when the refractory for repair is inserted into the snorkel, the joint material provided on the outer surface (outer peripheral surface) of the refractory receives the residual heat of the furnace and becomes fluidized, so that the joint material is repaired. The gap between the refractory and the sleeve-like material is densely filled, and the sleeve-like refractory is quickly fixed to the repair surface due to the carbon bonding of the joint material.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a longitudinal sectional view of a main part, FIG. 2 is a perspective view of a refractory for repair, and FIG. 3 is a process drawing. As shown in FIG. And has a role as a flow pipe for molten steel.

The snorkel 1 comprises a reflux tube 3 integrally fixed to a vacuum tank 2 and a dip tube 5 which is detachably attached to the reflux tube 3 with a flange 4. The immersion tube 5
Removed at end of life and replaced with new one.

FIG. 2 is a perspective view of the repair refractory 6 used in the present invention. The main body of the repair refractory 6 is a sleeve-like (cylindrical) refractory 7 made of a standard refractory. If a refractory is used as a repair material, it is not possible to secure sufficient density to fill the part to be repaired at the site, but if a refractory is used, it will be molded in advance. A dense structure can be obtained by means such as pressurization and vibration, and the durability is excellent.

A joint material (cylindrical joint layer) 8 is previously provided on the outer surface (outer peripheral surface) of the sleeve-like refractory 7. The material of the joint material 8 is obtained by adding pitch and / or thermoplastic resin as a binder to the refractory aggregate.

As a method of providing the joint material 8 on the outer surface of the sleeve-like refractory 7, for example, an outer frame (not shown) is provided outside the sleeve-like refractory 7 at an interval corresponding to the thickness of the joint material 8. It is possible to adopt a method in which a material is placed in the gap between the sleeve-shaped refractory and the outer frame.

The joint material 8 has a pitch and / or a thermoplastic resin added to the binder, so that the joint material 8 softens and flows when heated. Therefore, when the joint material is charged between the sleeve-shaped refractory and the outer frame in a state where the joint material has been heated and fluidized in advance, the joint material is integrated with the sleeve-shaped refractory 7 by cooling and solidifying after the charge, thereby forming a joint layer.

When the compound of the joint material 8 is charged between the sleeve-like refractory 7 and the outer frame, it may be charged in a powder state without heating. In this case, after the introduction, the outer frame is heated or the like to fluidize the joint material after the introduction, thereby achieving integration with the sleeve-like refractory 7.

In the composition of the joint material 8, as the refractory aggregate, for example, alumina, silica, alumina-silica, magnesia, calcia, magnesia-calcia, spinel, or the like is used as a main material. The particle size is preferably 5 mm or less,
More preferably, it is 3 mm or less.

The pitch of the joint material 8 as a binder is preferably a solid product having a fixed carbon content of 60%. Further, a specific example of the thermoplastic resin is a novolak type phenol resin. The mixing ratio is 10 ~
About 20 wt% is added. If the amount of binder is too small, joint material 8
When the amount of the binder is too large, the joint material 8 becomes porous and the bonding strength is poor.

If necessary, metal powder, silicon carbide, volatile silica, clay, fibers and the like may be added to joint material 8 in an appropriate amount. For example, the attachment of metal powder is effective in imparting tissue strength and preventing oxidation of carbon components. Specific examples are Al, Si, Mg and alloys thereof, and a preferable addition ratio is 1 to 10% by weight on the outside.

The thickness of the joint material 8 is preferably 3 to 35 mm.
If it is less than 3 mm, it is not easy to form the layered joint material 8 on the outer surface of the sleeve-shaped refractory 7. If it exceeds 35 mm, in repairing the snorkel 1 by inserting the refractory 6 for repair into the surface to be repaired, the time until the joint material 8 is fluidized by heating and reaches solidification becomes longer, Poor speed of repair.

The preferable thickness of the joint material 8 with respect to the sleeve-like refractory 7 is 1/5 of the thickness of the sleeve-like refractory.
It is as follows. If the thickness is larger than this, the sleeve-shaped refractory 7 becomes thin, so that the effect of the corrosion resistance of the sleeve-shaped refractory 7 cannot be sufficiently exhibited.

At the time of repairing the snorkel 1, as shown in FIG. 3 (A), first, with the immersion pipe 5 attached to the reflux pipe 3, the refractory for repair 6 is inserted into the inner hole surface thereof. Pre-cut to the extent possible. Cutting can be performed, for example, with a boring bit 9 or the like.

Next, as shown in FIG. 3B, the repair refractory 6 is inserted into the snorkel 1 from below. Since the repair refractory 6 has a considerable weight, it is preferable to use a powered lifting device such as a table lift 10 for the insertion.

The repair method of the present invention is performed hot to increase the operation rate of the vacuum degassing apparatus. For this reason, the internal temperature of the snorkel 1 at the time of repair is in a high-temperature residual heat state of 500 to 700 ° C. Therefore, when the refractory for repair 6 is inserted as shown in FIG. Lumber 8
Is fixed to the repaired surface by the fluidization of carbon and subsequent carbon bonding.

When ordinary mortar is used as the joint material 8, after the refractory for repair is inserted, the refractory for repair must be supported until the refractory for repair is held on the repair surface. Must be repaired quickly. On the other hand, in the present invention, since non-aqueous pitch and / or thermoplastic resin is used as a binder of the joint material, solidification is fast, and adhesion is large due to carbon bonding. Therefore, the repairable refractory 6 after insertion immediately and firmly adheres to the repaired surface.

The immersion pipe 5 is connected to the reflux pipe 3 by flange joining.
In the conventional snorkel repair, only the recirculation pipe 3 is often repaired. However, the flange joint is a place where the invasion of the air is likely to occur, and the joint material is inferior in density to the repair material made of a fixed refractory, and has no sufficient effect in preventing the invasion of the air.

On the other hand, according to the present invention, the inner surface (inner peripheral surface) of the snorkel 1 is cut with the immersion tube 5 attached to the reflux tube 3, and the reflow tube 3 is provided with an integral repairable refractory material 6.
And the immersion pipe 5 are repaired at the same time, so that the atmosphere invading from the flange joint is cut off by the repair refractory 6 and is excellent in the effect of preventing nitrogen pickup which causes molten steel contamination.

Further, the repair refractory 6 used in the present invention.
The joint becomes extremely long because the reflux pipe 3 and the immersion pipe 4 are repaired at the same time, and the weight increases by that much, but there is no problem such as falling off due to the strong carbon bond of the joint material 8.

In the present invention, as shown in FIG. 1, a hopper 11 storing a filler material 8b for replenishment may be provided at the upper end of the sleeve-like refractory 7. An annular opening 12 is opened at the lower end of the hopper 11, and the lower end opening 12 is directed to the outer peripheral surface of the sleeve-like refractory 7.

Since the joint material 8 provided integrally with the outer periphery of the sleeve-like refractory 6 sinks by fluidizing during repair, the joint material 8 is provided at the upper end between the repair refractory 6 and the repair surface. Voids are created without being filled. Therefore, when the hopper 11 storing the filler material 8b for replenishment is provided, the gap formed at the upper end between the sleeve-like refractory 7 and the repair surface is filled with the filler material 8b for replenishment from the hopper 11. Repairs will be more complete as they can.

The filler joint material 8b may be put into the hopper 11 in the form of powder, for example. After the sleeve-like refractory 6 is inserted to the upper end of the snorkel 1, for example, a shutter (not shown) is opened. When opened and dropped from the lower end opening 12, the replenishing joint material 8b is fluidized by residual heat and is filled in the gap.

[0034]

EXAMPLES Table 1 shows the materials of the refractory for repair, the time required for repair, and the number of usable charges of the snorkel after repair for the examples of the present invention and comparative examples. Each example is R
The present invention was applied to repair of a snorkel of an H-type vacuum degassing apparatus, and in each case, the repair of the snorkel after the 40 charge treatment was hot repaired. The inner surface temperature of the snorkel during repairs is about 6
It was 00 ° C.

In Example 1, Example 2, and Comparative Example 1,
With the immersion pipe attached to the reflux pipe, the inner hole of the snorkel 1 to be repaired was cut with a boring bit to the extent that refractory for repair could be inserted, and then a sleeve-shaped sleeve made of the material shown in the table was used. The repair refractory was inserted into the snorkel hole. Of these, Example 2 was repaired in the same manner as in FIG. 1 with a hopper storing joint materials for replenishment of refractory for repair.

In Comparative Example 2, a metal cylindrical core was inserted into the inner hole of the snorkel to be repaired, and a water-based press-fitting material was press-filled between the repair surface and the core through a through hole provided in the core. did. In this case, the immersion tube and the reflux tube were also repaired at the same time.

In Comparative Example 3, for the snorkel to be repaired, the immersion pipe was removed, and then a metal cylindrical core was inserted into the inner hole of the reflux pipe. Non-aqueous repair materials were introduced.

[0038]

[Table 1]

In Examples 1 and 2, the repair refractory was adhered to the snorkel at the same time as the snorkel was inserted into the refractory, enabling quick repair. In addition, the snorkel regenerated in this repair shows excellent durability. Although not shown in the table, it is also excellent in preventing nitrogen pickup.

Comparative Example 1 differs from the Example of the present invention in that the material of the joint material is an aqueous mortar. After the repair refractory is inserted into the snorkel, the repair refractory must be supported from below until the adhesive strength of the mortar is developed, and the repair time is considerably longer than that of the embodiment of the present invention. Also,
Due to the inferior adhesive strength of the refractory for repair and the porous nature of joints, the durability after repair and the effect of preventing nitrogen pickup are also inferior to those of the present invention.

In Comparative Example 2, the entire refractory for repair is made of an irregular refractory. Since amorphous refractories do not have a dense structure, they have poor durability and an effect of preventing nitrogen pickup.

In Comparative Example 3, it took time to attach and detach the dip tube,
Quick repair was not possible. Further, the prevention of intrusion into the atmosphere from the flange connecting the immersion pipe and the reflux pipe is incomplete, and the effect of preventing nitrogen pickup is poor. On the other hand, in each embodiment of the present invention, the sleeve-like refractory is formed in the inner hole of the snorkel over the immersion pipe and the reflux pipe, so that the flange joint is closed, thereby preventing the invasion of the atmosphere. .

[0043]

As described above, according to the present invention, hot repair of a snorkel for a vacuum degassing device can be performed quickly and reliably, the number of repairing steps can be reduced, the operation rate of the vacuum degassing device can be improved, and And has a remarkable effect such as prevention of nitrogen pickup.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of a refractory for repair according to the present invention.

FIG. 3 is a view showing a repair process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Snorkel 2 Vacuum layer 3 Reflux pipe 4 Flange 5 Dip pipe 6 Repair refractory 7 Sleeve refractory 8 Joint material 8b Refill joint material 11 Hopper 12 Lower end opening of hopper

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koichi Kudo, Inventor Koichi Nishinosu, Oita, Oita City, Oita Prefecture Nippon Steel Corporation Oita Works (72) Inventor Koichi Nishi 1-3-1, Shinama, Araimachi, Takasago City, Hyogo Prefecture No. Harima Ceramics Co., Ltd. (72) Inventor Naotoshi Yasuda 1-3-1 Shinhama, Arai-machi, Takasago City, Hyogo Prefecture F-term in Harima Ceramics Co., Ltd. 4K013 CE09 4K051 LJ01 LJ03

Claims (4)

[Claims] 1. A hot-repair method for a snorkel for a vacuum degassing device, wherein after cutting an inner surface of a snorkel with a dip tube attached to a reflux tube, a sleeve-like refractory is inserted and fixed. Pitch and / or
Alternatively, a method for hot repairing a snorkel for a vacuum degassing device, wherein a joint material to which a thermoplastic resin is added is provided in advance on the outer surface of the sleeve-like refractory. 2. The joint material provided on the outer surface of the sleeve-shaped refractory material has a thickness of 3 to 35 mm and not more than 1/5 of the thickness of the sleeve refractory material. The hot repair method for a snorkel for a vacuum degassing apparatus described in the above item. 3. A hopper for storing a refill joint material at an upper end of the sleeve-like refractory, and a lower end opening of the hopper is directed to an outer surface of the sleeve-like refractory. The hot repair method for a snorkel for a vacuum degassing apparatus according to claim 1 or 2. 4. A joint material obtained by adding pitch and / or a thermoplastic resin as a binder to a refractory aggregate is provided in advance on the outer surface of the sleeve-like refractory. A repair refractory used in the hot repair method for a snorkel for a vacuum degassing apparatus according to any one of 2 and 3.