JPH0441613A - Method for repairing snorkel of vacuum degasifier - Google Patents

Abstract

PURPOSE:To repair the snorkel of a vacuum degasifier in a short time by filling a hydraulic repairing material between the snorkel and an insertion core from the lower end, then charging a void forming material at the site of a gas injection hole and filling a nonaqueous repairing material thereon. CONSTITUTION:A core 4 is inserted into a used snorkel 1, and the leakage of a repairing material from the lower end of the core 4 is prevented by a receiving base 5. A hydraulic repairing material 17 with alumina cement as a binder is firstly filled between the lower end of the snorkel 1 and the lower part of a gas injection hole 3. A heat-resistant void forming material 6 is then charged at the site of the hole 3, and a nonaqueous repairing material 27 with pitch and/or synthetic resin as a binder is filled thereon. The amt. of the pitch and/or synthetic resin to be added to a refractory aggregate is controlled to about 2-30wt.% of an increase. The nonaqueous repairing material 27 receives the furnace heat, hence the binder in the material is carbonized, and a carbon bonding structure excellent in resistance to corrosion and spalling is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for repairing a snorkel portion of a vacuum degassing device.

[Conventional technology]

In a DH type or RH type vacuum degassing device used for molten steel processing, the inner peripheral surface of a snorkel that sucks up or discharges molten steel between a ladle and a degassing tank is significantly worn out by the flow of molten steel. Therefore, the snorkel is repaired by using a core and inserting a repair material between the inner peripheral surface of the snorkel and the core. However, according to this repair, there is a problem in that the gas ejection hole provided on the inner circumferential surface of the snorkel to promote the suction of the molten steel flow into the degassing tank is blocked by the repair material.

Therefore, as shown in FIG. 2, in the repair using the core 4, a repair method in which a gap forming material 6 made of granules is introduced into the area below the gas ejection hole 3, and then a repair material 7 is introduced thereon. is proposed.

For example, it can be seen in Japanese Patent Application Laid-Open No. 116286/1986. According to this method, after repair, Snorkel 1
When the core 4 melts down due to contact with molten steel, the void forming material 6 falls and the gas nozzle 3 is exposed.
blockage is prevented.

[Problem to be solved by the invention]

However, the above method has the disadvantage that the area below the gas nozzle cannot be repaired. In addition, recently, non-aqueous repair materials have been used to repair snorkel parts, but while these repair materials have excellent corrosion resistance, they cure slowly and therefore take a long time to repair.

[Means to solve the problem]

The present invention is a method for solving the above-mentioned conventional problems in repairing the snorkel section of a vacuum degassing device. Insert the core into the snorkel, fill the space between the snorkel and the core from the bottom of the snorkel to the bottom of the gas nozzle with a hydraulic repair material that uses alumina cement as a binder, and then fill the area of the gas nozzle with a hydraulic repair material that uses alumina cement as a binder. The method is characterized in that a void-forming material is introduced, and then a non-aqueous repair material containing pitch and/or synthetic resin as a binder is filled above the void-forming material.

The present invention will be explained in more detail based on FIG.

The snorkel 1 to be repaired has a gas supply pipe 2 buried therein, and its gas ejection holes 3 are open to the inner circumferential surface of the snorkel 1.

The core 4 is inserted into the used snorkel 1 from the bottom. A distance corresponding to the thickness of the repair material is provided between the snorkel 1 and the core 4. The core 4 is made of metal, for example, which melts away when it comes into contact with molten steel. Japanese Patent Publication No. 54-10740
As in Publication No. 4, a core covered with a sleeve-shaped refractory may be used.The lower end of the core 4 is provided with a receiver 5, for example, to prevent leakage of the repair material. After the core 4 is set as described above, first, a hydraulic repair material 17 containing alumina cement as a binder is filled between the lower end of the snorkel 1 and the lower part of the gas jet hole 3. The proportion of alumina cement is preferably about 1 to 30 wt% relative to the refractory aggregate.
Since the hydraulic repair material 17 uses alumina cement as a binder, it hardens more quickly than non-aqueous repair materials. There is a concern that the repair material located below the snorkel may fall if it is not sufficiently cured, but by using this quick-curing hydraulic repair material in the lower part, the repair time of the present invention is greatly shortened. Ru.

Next, the gap forming material 6 is introduced into the gas ejection hole 3. The material of the void forming material 6 is not particularly limited as long as it has heat resistance, and examples thereof include granular and/or fibrous materials such as fire-resistant powder, natural sand, metallurgical slag, glass powder, ceramic fiber, and asbestos. can be used. When a metallic core is used, the void forming material 6 falls due to melting of the core. Even if the core is not melted away and the void-forming material 6 remains, the gaps between the particles or fibers of the void-forming material 6 serve as ventilation holes, and the gas ejection holes are not blocked. In order to ensure that the core does not fall due to melting or that the air flow between the particles and fibers is ensured, the particle diameter and fiber diameter of the void forming material 6 are preferably large. Further, it is preferable to fill the gap forming material 6 with a certain amount of margin in the height direction so that the gas ejection hole 3 can be reliably covered with the gap forming material 6.

When the snorkel 1 is used, when the core 4 melts down due to contact with molten steel, the gap forming material 6 falls and the gas ejection holes 3 are exposed. In addition, cores that are made of a metal core with a refractory exterior, or that are made entirely of refractories, will not melt away, but the void forming material 6
The spaces between the particles or fibers become ventilation paths, and the gas ejection holes 3
will not be blocked.

After the void forming material 6 is introduced as described above, the drainage system repair material 27 is filled above it. The non-aqueous repair material 27 uses pitch and/or synthetic resin as a binder. Specific examples of the synthetic resin include thermoplastic phenol resin, furan resin, polyurethane resin, and the like. Among them, phenol resins with a large amount of fixed carbon are preferred. A thermosetting resin may be used in combination with this thermoplastic resin. The amount of pitch and/or synthetic resin added to the fire-resistant aggregate is, for example, 2 to 2.
It is set to 30wt%. The non-aqueous repair material 27 is fluidized by melting of the binder in response to furnace heat, and after being filled, the bond rows are carbonized to form a carbon connective tissue with excellent corrosion resistance and durable poling property. Although the area around the gas ejection hole of the snorkel suffers from more significant erosion than other parts, the non-aqueous repair material 27 has an excellent effect of improving the corrosion resistance around this gas ejection hole.

In the above hydraulic repair material 17 and non-aqueous repair material 27, the type of aggregate is not particularly limited, and examples include magnesia, spinel, chromite, alumina, silica,
Alumina-silica, zircon, zirconia, silicon carbide,
Alternatively, the main material is one or more selected from brick scraps made from these aggregates. In the case of the non-aqueous repair material 27, since there is no problem of digestion, dolomite, lime, etc. may also be used.

In addition to one or more aggregates, the hydraulic repair material 17 and the non-aqueous repair material 27 include, for example, clay, silica flour, carbon, refractory ultrafine powder, wetting agent, dispersant, metal powder, antioxidant, and sintering agent. ,
One or more selected from foaming agents, slaked lime, silica sol, alumina sol, organic fibers, inorganic fibers and metal fibers may be added. Further, binders other than those specified in the present invention can also be used in combination.

Although not shown in the figure, in the present invention, when filling the repair material and introducing the gap-forming material, the repair material is inserted between the snorkel and the core from above, or the repair material is press-fitted from the inside surface of the core. Well-known filling W (for example, JP-A-6
1-116286, Japanese Unexamined Patent Publication No. 62-120419, and Japanese Utility Model Application No. 1-177259).

【Example〕

In Example 1 and Comparative Examples 1 to 3, a suction pipe (inner diameter 8
00 x height 2000m) was repaired. Example 2 is 30
Immersion tube and reflux tube (inner diameter 500 x height 1600 m) corresponding to the snorkel part of a 0t R8 vacuum degassing device
) was repaired.

In Example 1, the outer periphery of the metallic cylinder was covered with a magnesia-chromium mineral brick with a thickness of 50 cm, and a core with an open portion facing the gas injection hole was used.6 Other Examples and Comparative Examples used a metal core.

Example 1 After putting in the following hydraulic repair material and filling the area from the lower end of the snorkel to the bottom of the gas outlet with the hydraulic repair material, 51
A void-forming material made of sized magnesia grains was introduced below, and the gas ejection hole was covered with the void-forming material to a height of about 100 m. Next, the following drainage system repair material was filled on top of it.

Composition of hydraulic repair material: Sintered alumina 3-1% 40t% Sintered alumina 1m or less 55wt% Silica flour 5wt% Dispersant External 0.511t% Composition of non-aqueous repair material: Magnesia cleaning power -3 ~1m 50vt% magnesia clinker 1■ or less 50wt% bit
H 1■ or less External hook 10 wt% gold wing aluminum 0.2 m or less External hook 5 wt% Example 2 The following hydraulic repair material was added, and the area from the bottom of the snorkel to the bottom of the gas outlet was filled with the hydraulic repair material. 3. Thereafter, a pore forming material made of limestone grains sized to 3 m or less and alumina-siliceous fibers was introduced, and the gas ejection hole was covered with the pore forming material to a height of approximately Loom.

Then, the following non-aqueous repair material was filled thereon. In addition, in the case of R) type 1 vacuum degassing equipment, the gas jet pipe is installed on the immersion pipe side, so the part to be filled with the non-aqueous repair material is above the gas jet hole of the immersion pipe and the entire reflux pipe. .

Composition of hydraulic repair material: Spinel (MgO-Al□0. system) 3-1m
+++ 40wt% spinel (MgO-Al, O,
(type) inn or less 55wt% alumina ultrafine powder 1μm or less 5tgt% Dispersant External layer 0.5
Composition of 1% non-aqueous repair material; Magnesia-chromium mineral brick waste 3-inn 5
0 warning t% magnesia chromium mineral brick waste 1 unit or less
45wt% carbon black
5% phenol resin 2~0.1mm
External charge 15wt% Comparative Example 1 The area below the gas nozzle was filled with magnesia grains sized to 511111 or less. Next, a non-aqueous repair material having the composition shown in Example 1 above was filled above it.

Comparative Example 2 The region of the gas ejection hole was filled with alumina particles sized to three or less particles, and the upper and lower portions were filled with a hydraulic repair material having the composition shown in Example 1 above.

Comparative Example 3 The region of the gas ejection hole was filled with magnesia grains sized to a size of 5 m or less, and the upper and lower parts thereof were filled with a non-aqueous repair material having the composition shown in Example 1 above.

On each of the above sides, in Examples 1 and 2, the lower part is filled with a hydraulic repair material that hardens quickly, so the snorkel can be used immediately after repair, and the area around the gas nozzle has high corrosion resistance. We were able to obtain an excellent repair effect. Further, in Example 1, by using magnesia grains as the void forming material, the grain boundaries of the magnesia grains served as ventilation passages, thereby preventing clogging of the gas ejection holes. In Example 2, the metallic core melted away on contact with molten steel, and the pore-forming material made of limestone grains and alumina-siliceous fibers fell, thereby preventing the gas outlet from clogging.

On the other hand, in Comparative Example 1, the portion below the gas nozzle cannot be repaired, so the durability after repair is poor. Comparative Example 2 has poor corrosion resistance around the gas nozzle. In Comparative Example 3, the lower part was also filled with a non-aqueous repair material, so if you tried to use it immediately after repair, the repair material at the lower end of the snorkel would fall, so it took a considerable amount of time to complete the repair.

It should be noted that the present invention is not limited to the above examples, and for example, for specific materials of hydraulic repair materials and non-aqueous repair materials, formulations other than those shown in each example may be used as long as they are within the scope of the present invention. You may use compositions.

〔Effect of the invention〕

The effects of the present invention are as follows.

■ The entire inner circumferential surface of the snorkel can be repaired without clogging the gas outlet.

■ By filling the lower part of the snorkel with a hydraulic repair material that hardens quickly, it is possible to retain the non-aqueous repair material that hardens slowly, significantly shortening the repair time.

■ Non-aqueous repair materials improve corrosion resistance around gas vents. Hydraulic repair materials are inferior in corrosion resistance compared to non-aqueous repair materials, but perhaps because the gas ejected inside the snorkel flows upward, filling the hydraulic repair material downwards prevents the gas from blowing out. The corrosion resistance of the surrounding area will not deteriorate.

As described above, the repair method of the present invention not only prevents clogging of the gas nozzle, but also repairs the entire inner peripheral surface of the snorkel, shortens the repair time, and provides excellent corrosion resistance around the gas nozzle. The effects are extremely large, such as reducing repair man-hours and improving the availability of vacuum degassing equipment.

[Brief explanation of drawings]

Each of the figures is a vertical sectional view showing a method for repairing the snorkel part of a vacuum degassing device.
FIG. 2 shows the conventional method. 1... Snorkel 6... Gap forming material 2... Gas supply pipe 7... Repair material 3... Gas ejection hole
17... Hydraulic repair material 4... Core 5... Receiver 27... Non-aqueous repair material

Claims (1)

[Claims] (1) During hot repair of a snorkel with a gas nozzle opening on the inner circumferential surface, insert the core into the snorkel and place alumina cement between the snorkel and the core from the bottom of the snorkel to the bottom of the gas nozzle. After filling with a hydraulic repair material using as a binder, a void-forming material is introduced into the gas outlet area, and then a non-aqueous repair material using pitch and/or synthetic resin as a binder is filled above it. A method for repairing the snorkel part of a vacuum degassing device.