JP2019173163A - Gas blowing plug and method for manufacturing same - Google Patents

Abstract

To provide a gas blowing plug for gas for improving following property to movement of a dense refractory layer on an outer peripheral side of a metal plate at the time of drawing the gas blowing plug out as well as circumventing a problem such as deformation of the metal plate so that the dense refractory layer can be drawn out together with the metal plate.MEANS FOR SOLVING THE PROBLEM: The gas blowing plug has a metal plate 2 at a boundary between refractory layers. The plug has an adhesive layer 4 for bonding the metal plate 2 and an outer peripheral refractory layer 3 disposed between the metal plate 2 and a dense refractory layer (the outer peripheral refractory layer) 3 on an outer peripheral side of the metal plate 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gas blowing plug attached to the bottom of a molten steel container such as a ladle or a tundish, and a method for manufacturing the same.

The plug for gas blowing is a functional refractory that performs refining treatment such as homogenization of the molten steel temperature and components and floating removal of non-metallic inclusions by blowing gas into the molten steel in the molten steel vessel and stirring the molten steel. .
Normally, a gas blowing plug is used repeatedly, and its life is 5 to 30 times. The most important characteristic is the stable discharge of gas bubbles. That is, in a gas blowing plug, it is necessary to stably blow a gas bubble of a predetermined size and amount into a molten steel from a predetermined gas discharge region.

In order to ensure the stable discharge of this gas bubble, a metal plate is arranged on the outer peripheral side of the breathable refractory near the center of the gas blowing plug to suppress or prevent gas leakage to the outer peripheral side. There is a plug for gas blowing.
The gas blowing plug is replaced with a new gas blowing plug after use. In such a gas blowing plug with a metal plate arranged on the outer peripheral side, the metal plate is fused to the tuyere at the bottom of the molten steel container and gas is discharged. It may be difficult to remove the plug for blowing.
Therefore, there is a metal refractory disposed on the outer peripheral side of the metal plate, and the dense refractory is used as the outermost peripheral surface.

When replacing the gas blowing plug, a method is used in which a gas supply pipe connected to a case made of a metal plate of the gas blowing plug (hereinafter also referred to as “metal case”) is loaded and pulled out from the bottom of the molten steel container. Is common.
In such a method, the refractory located on the center side of the gas blowing plug from the metal case can be pulled out together with the metal case, but the metal plate and the refractory have a weak adhesive force. At least part of the refractory outside the case may remain on the tuyere due to seizure.
In order to install a new plug for gas blowing, it is necessary to remove this residue, but it is maintained by removing the residue or repairing the tuyere during this removal operation. Longer times may interfere with the refining and casting process.

  Patented for the purpose of improving the integrity of the outermost dense refractory and the metal part of the gas blowing plug to prevent the outermost dense refractory from remaining on the tuyere side Reference 1 states that “a cylindrical iron skin (corresponding to a metal case) surrounding the outer peripheral surface of the gas blowing plug body, a reinforcing member integrally fixed to the outer peripheral surface of the iron skin, and a refractory layer Injecting porous gas for molten metal, comprising a cylindrical castable layer coated on the outer peripheral surface of the iron skin so as to come into contact, and the reinforcing member is embedded in the castable layer to reinforce the castable layer A “plug” is disclosed.

Japanese Patent Laid-Open No. 2002-3931

In the gas blowing plug having the structure as described in Patent Document 1 described above, the effect of causing the castable layer on the outer peripheral side of the metal case to follow the movement of the metal case is obtained when the gas blowing plug is pulled out. .
However, in this structure,
1. When installing a reinforcing member on the metal case, the metal case is likely to be deformed, which may impair the adhesion of the contact part with the gas blowing plug body (breathable refractory).
2. If a reinforcing member is installed on the metal case, there will be many foreign objects in the space where the castable refractory is poured, and the workability of the castable refractory will be reduced.
3. If a reinforcing member is installed on the metal case, there will be many foreign objects in the space where the castable refractory is poured, and the fluidity and fillability of the castable refractory will deteriorate, resulting in poor quality (fragile parts, defects, etc.). Easier,
4). It takes a lot of labor and cost to install the reinforcing member on the metal case.
There are problems such as.

  The problem to be solved by the present invention is to solve the problems related to the above-mentioned Patent Document 1, and to follow the movement of the dense metal refractory layer on the outer peripheral side of the metal plate when the gas blowing plug is pulled out. It is to provide a gas blowing plug capable of enhancing the properties, that is, capable of pulling out a dense refractory layer together with the metal plate.

The present invention is basically based on enhancing the adhesion between the metal plate and the dense refractory layer on the outer peripheral side thereof.
That is, the gist of the present invention is the following 1 to 8 gas blowing plugs and 9 to 12 gas blowing plug manufacturing methods.
1.
In a gas blowing plug including a metal plate at a boundary portion between refractory layers, the metal plate and a dense refractory layer (hereinafter referred to as an “outer refractory layer”) on the outer peripheral side of the metal plate. A gas blowing plug including a layer having a function of bonding a metal plate and the outer peripheral refractory layer (hereinafter referred to as an “adhesion layer”).
2.
2. The plug for gas blowing according to 1 above, wherein the adhesive layer contains silicate.
3.
3. The gas blowing plug according to 2 above, wherein the silicate is derived from water glass.
4).
The adhesive layer contains a total of 10% by mass or less of at least one kind of refractory raw material particles of alumina, alumina-silica, zircon, spinel or silicic acid having a particle size of 0.5 mm or less. The plug for gas blowing as described in any one of 3 above.
5.
5. The gas blowing plug according to 1 above, wherein the adhesive layer contains orthophosphoric acid or phosphate.
The adhesive layer contains a total of 60% by mass or more and 70% by mass or less of at least one kind of refractory raw material particles of alumina, alumina-silica, zircon, spinel, or silicic acid having a particle size of 0.5 mm or less. The plug for gas blowing as described in 5 above.
7.
The plug for gas blowing according to any one of 1 to 6, wherein the maximum thickness of the adhesive layer is 0.5 mm or more and 2 mm or less.
8).
8. The gas blowing plug according to any one of 1 to 7, wherein at least a part of the adhesive layer includes a portion joined to the outer peripheral refractory layer by unevenness.
9.
9. The method for producing a gas blowing plug according to any one of 1 to 8, wherein a breathable refractory is disposed on the inner peripheral side of the metal plate, and silicate or orthophosphoric acid is disposed on the outer peripheral side of the metal plate. Alternatively, a gas blowing plug including a step of forming an adhesive layer with a material containing phosphate and setting an outer peripheral refractory layer so as to cover the adhesive layer without passing through a heat treatment step after the formation of the adhesive layer. Manufacturing method.
10.
10. The method for producing a gas blowing plug as described in 9 above, wherein the material containing silicate is water glass.
11.
The water glass has a SiO ₂ / R ₂ O (R: alkali metal) molar ratio of 2.35 to 3.35, orthophosphoric acid is orthophosphoric acid of H ₃ PO ₄ , and phosphate is 11. The method for producing a gas blowing plug as described in 10 above, wherein the molar ratio represented by Al ₂ O ₃ / P ₂ O ₅ is 0.25 or more and 0.40 or less.
12
The method for producing a gas blowing plug according to any one of 9 to 11, wherein the step of installing the outer peripheral refractory layer includes pouring, indenting, or spraying an amorphous refractory.

According to the present invention, when the gas blowing plug is pulled out from the bottom (tuyere) of the molten steel container, the outer refractory layer is pulled out together with the inner metal plate without the outer refractory layer remaining in the tuyere. Can do.
Moreover, since there is no need to install a reinforcing member on the metal case as in Patent Document 1, there is no deformation of the metal case when the reinforcing member is installed on the metal case. There is no risk of impairing the adhesion of the contact portion with the material), and there is no deterioration in workability when installing castable refractories, etc., and poor quality due to a decrease in fluidity and fillability of castable refractories ( (Fragile parts, defects, etc.) are not easily generated, and a great amount of labor and cost for installing the reinforcing member are not required.

The cross-sectional image figure which shows one Embodiment of the plug for gas blowing of this invention. The cross-sectional image figure explaining a state when pulling out the plug for gas blowing of FIG. 1 from a tuyere. Sectional image figure explaining the state when pulling out the plug for gas blowing (comparative example) which is not provided with the contact bonding layer from a tuyere.

FIG. 1 is a cross-sectional image view showing an embodiment of a gas blowing plug of the present invention.
In the figure, a breathable refractory layer 1 is disposed on the inner peripheral side of a case-shaped metal plate 2, and an outer peripheral refractory layer (dense refractory layer) is disposed on the outer peripheral side of the metal plate 2 via an adhesive layer 4. 3 is arranged. A gas introduction pipe 5 is connected to the breathable refractory layer 1, and gas is discharged from the upper end surface of the breathable refractory layer 1.
In this way, in the present invention, the metal plate 2 and the outer peripheral refractory layer 3 are joined via the adhesive layer 4, so that the gas blowing plug is connected to the tuyere at the bottom of the molten steel container as shown in FIG. The outer refractory layer 3 can be pulled out together with the metal plate 2 inside the outer refractory layer 3 without leaving the outer refractory layer 3 in the tuyere 6.

  Hereinafter, an outer peripheral refractory layer (dense refractory) is used as an adhesive layer formed by applying water glass or a liquid containing primary aluminum phosphate, which is a kind of normal phosphoric acid or phosphate, to a metal plate. The embodiment of the present invention will be described in detail by taking the case of using a castable refractory as the layer.

  Here, the term “dense refractory” refers to a refractory having a gas permeability lower than that of a porous breathable refractory forming a gas flow or blowing portion.

Water glass is represented by R ₂ O.nSiO ₂ .mH ₂ O as a general molecular formula, R represents an alkali metal such as Na, K, Li, etc., and the coefficient n represents the number of moles of SiO ₂ . Industrially, those having n in the range of 0.5 to 4.2 are produced, and those having n of about 2 to 4 are generally used. The coefficient m represents the number of moles of H ₂ O and is commercially available in the range of about 2.0 to 3.5.

This water glass has a SiO ₂ / R ₂ O (R: alkali metal) molar ratio of No. 2 water glass (viscosity of about 200 mPa · s) or No. 3 water glass (viscosity of about 2). Most preferably, 80 mPa · s) is used.
The chemical components after heat treatment at 1050 ° C. according to JIS R 2212-5 of No. 2 water glass are 51 mass% to 61 mass% in SiO _{2 and} 17 mass% to 25 mass in alkali metal oxide. It is below mass%.

Orthophosphoric acid used was orthophosphoric acid of H ₃ PO ₄ .
Also, aluminum primary phosphate is represented as a general formula by _{Al 2 O 3 · 3P 2 O} 5 · 6H 2 O, molar ratio for industrial indicated by _{Al 2 O 3 / P 2 O} 5 is 0. The thing of 25-0.40 is marketed.
The primary aluminum phosphate used in this embodiment is P ₂ O ₅ = 30% by mass to 32% by mass, Al ₂ O ₃ = 6.8% by mass to 7.8% by mass, and the molar ratio is 0. .33, the viscosity is about 25 mPa · s.

When applying to a metal plate, the metal plate to be applied when installed in a gas blowing plug is generally frusto-conical, so either side is facing down regardless of the orientation of the metal plate. Direction, that is, the direction of lowering due to gravity. For this reason, water glass must have shape retention that does not flow down during coating.
In addition, in order to install the water glass thinly on the entire surface of the metal plate by coating or the like, it is preferable that the viscosity is not too low and not too high because the spreadability is also necessary.
Mainly for these reasons, the water glass is preferably No. 2 or No. 3, and other than that, normal phosphoric acid or monoaluminum phosphate is preferred.

Next, a method for manufacturing a gas blowing plug will be described. For example, a liquid containing No. 2 water glass (viscosity of about 200 mPa · s) or normal phosphoric acid or primary aluminum phosphate is applied to the outer periphery of a truncated conical metal plate. Apply to the entire side surface with a thickness of 0.5 to 2 mm by brushing, spraying or dipping. After that, without passing through a heat treatment step, a space corresponding to the thickness of the outer peripheral refractory layer made of dense refractory is formed on the outer peripheral side of the frustoconical metal plate, and a mold is installed on the outer side, Castable refractory is cast while applying vibration.
Thus, casting a castable refractory without heat-treating a water glass layer or a layer containing orthophosphoric acid or monoaluminum phosphate as an adhesive layer is possible while the adhesive layer is maintained in a soft state. Means to contact with castable refractories. When the castable refractory is in contact with the soft adhesive layer, the protruding portion of the coarse aggregate (for example, the maximum particle size is 5 mm) in the castable bites into the adhesive layer.
Due to this phenomenon, the contact surface between the adhesive layer and the outer refractory layer becomes uneven, and the adhesion area is expanded and the particle surface having a complicated and irregular shape fixes the adhesive layer, so that adhesion by the so-called anchor effect is achieved. Power increases.

The thickness of the adhesive layer is the maximum thickness considering the change due to being bonded to the outer peripheral refractory layer or reacting with the outer peripheral refractory layer and being integrated with the outer peripheral refractory layer or absorbed into the pores. And about 0.5 mm to about 2 mm is preferable.
The degree of this change varies depending on the chemical composition of the adhesive layer itself and the chemical composition of the outer refractory layer, particle composition, physical properties such as porosity, and the like. You can optimize.

In addition to the No. 2 water glass, water glass with different SiO ₂ / R ₂ O ratios (No. 1, No. 3, No. 4) and R can be used as the basic part of the silicate-containing adhesive layer. Na and K, Li can also be used. In addition to water glass, powdered alkali silicate can be dissolved in water.
Moreover, the above-mentioned normal phosphoric acid or monoaluminum phosphate can be applied as a material that is a basic part of the adhesive layer.
In order to enhance the function to improve viscosity, shape retention, etc., these adhesive layers are made of inorganic refractory materials such as alumina, silica and zirconia, various organic substances such as dextrin and cellulose, various clays, inorganic or organic fibers. Etc. can be added.

  After casting of castable refractory, after curing or natural drying for about one day, heat treatment is performed at a temperature of 300 ° C or higher with a dryer. By this heat treatment, the water glass layer described above becomes strong and a strong bonding state can be obtained.

In order to improve the strength of the silicate-containing adhesive layer, commonly used alkali silicate curing agents such as oxides and hydroxides containing components such as Mg and Ca are added. be able to.
Furthermore, silicate-containing adhesive layers or adhesive layers containing orthophosphoric acid or monoaluminum phosphate have shape retention and spreadability improvement, strength improvement, fire resistance, corrosion resistance, etc. during installation of these layers. In order to improve, refractory raw material particles having a size (particle size) of not more than the thickness of the adhesive layer to be set, preferably 0.5 mm or less can be contained. In order to maintain or ensure the spreadability and the like, the size (particle size) of the refractory raw material particles is more preferably about 0.2 mm or less.

  These refractory raw material particles contribute to the sintering and reaction even between the particles, the main constituent material (silicate) in the adhesive layer, the metal plate, etc., and ensure the adhesion between the adhesive layer and the metal plate, or In order to increase it, an oxide is preferable.

  If the content of the refractory raw material particles increases, the spreadability and uniformity may decrease, and discontinuous parts may occur in the adhesive layer, which may cause cracks. In this case, the total amount in the adhesive layer is preferably about 10% by mass or less. On the other hand, in the case of an adhesive layer containing normal phosphoric acid or primary aluminum phosphate, the total amount in the adhesive layer is preferably about 60% by mass or more and about 70% by mass or less.

  These refractory raw material particles can contain one or a plurality of kinds regardless of whether they are artificial or natural such as sintering and electromelting. Specific examples of these refractory raw material particles include alumina, mainly corundum, mullite, sillimanite, kaolinite and other clays, chamottes, rholite, ceramics, and other alumina-silica, zircon, spinel, and quartz. Silicic acids such as cristobalite, tridymite, and glass can be used.

  The peripheral refractory layer (dense refractory layer) is not limited to a castable refractory, but may be a pre-formed refractory (hereinafter also referred to as “pre-formed body”), or other construction forms such as blowing or thrusting. It may be an irregular refractory. In the case of a preform, it is preferable to increase the adhesive strength with the adhesive layer by making the contact surface with the adhesive layer as uneven as possible.

<Example>
Hereinafter, examples of embodiments of the present invention will be described by way of specific examples.
A flat metal plate of 120 x 70 x 1.2 mmt is placed on the bottom of the metal frame, and water glass, or a liquid containing refractory material particles in water glass, normal phosphoric acid, or primary aluminum phosphate is placed on the metal plate surface. It was applied with a brush, and castable refractories were cast while being vibrated to a height of 30 mm after the application was completed. After curing for one day (curing and natural drying) in this state, heat treatment was performed at 1200 ° C. for 1 hour in an electric furnace, and then the bonding strength between the metal plate and the castable refractory was investigated.

The castable refractory has a maximum particle size of 5 mm, a proportion of particles having a particle size of 5 to 1 mm is about 50% by mass, Al ₂ O ₃ content is about 90% by mass, CaO content is about 2% by mass, 1000 ° C. An alumina-magnesia material having an apparent porosity after heat treatment of about 16% and a bending strength of about 4 MPa after heat treatment at 1000 ° C. was used.

  The workability (coating workability on metal plates) when applying a liquid containing refractory raw material particles to such water glass, regular phosphoric acid, or primary aluminum phosphate is ○ The case where there was difficulty was evaluated as △. This “slightly difficult” includes not only the difficulty of coating, which requires a force in the coating operation itself, but also the case where it is difficult to ensure uniformity in a small number of operations, that is, the case where so-called coating unevenness is likely to occur.

  As described above, as an index of the strength of adhesion between the adhesive layer and the castable refractory imitating the outer peripheral refractory layer, as described above, the castable refractory cast on the metal plate of 120 × 70 × 1.2 mmt through the water glass coating layer. With respect to the sample after heat treatment at 1200 ° C., the shear strength until the two peeled off was measured by applying a load in the vertical axis direction with an Amsler tester, and this measured value was evaluated as “joining strength”.

  Confirmation with the actual machine was made by checking whether or not the outer peripheral refractory layer (castable refractory layer) could be pulled out at the time of pulling out for replacement after using the gas blowing plug in each case. When sufficient, it evaluated as x.

  Tables 1 and 2 show the configuration and evaluation results of each example.

Examples 1 to 8 are examples based on No. 2 water glass.
Example 1 was application | coating only by No. 2 water glass, application | coating workability | operativity was favorable, there existed the uniformity of a coating film, and the coating-film thickness was able to ensure about 1-2 mm. The bonding strength was 2.1 MPa, which was significantly improved as compared to <0.1 of Comparative Example 1 which is a conventional technique having no adhesive layer.

Examples 2 to 8 are examples in which water glass No. 2 contains oxide refractory raw material particles. The oxide refractory raw material particles used had a size that passed through a sieve having an opening of 0.212 mm.
In Examples 2 to 6 in which the content of oxide refractory raw material particles was 10% by mass or less, the bonding strength was higher than that in the case of not containing oxide refractory raw material particles (Example 1). When the content of the raw material particles exceeds 10% by mass (Examples 7 and 8), the coating workability (extensibility, etc.) on the metal plate starts to deteriorate and unevenness occurs on the coated surface, resulting in a decrease in bonding strength. It became a trend. For this reason, for Examples 7 and 8, confirmation with an actual machine (pull-out test) was not performed.

  Examples 9 to 14 are examples based on No. 3 water glass. It was the same tendency as the above-mentioned Examples 1-8 based on No. 2 water glass.

Examples 15 to 17 are examples based on primary aluminum phosphate. This primary aluminum phosphate has a lower viscosity than water glass (about 25 mPa · s), and if left as it is, there is a risk of dripping down during application to a metal plate. Particles were included.
As oxide refractory raw material particles, fine alumina powder having a size passing through a sieve having a mesh size of 0.212 mm was used. As shown in Examples 15 to 17, when the content of the fine alumina powder is 60% by mass or more and 70% by mass or less, the coating workability is good, the coating film is uniform, and the coating film thickness is about 1 to 2 mm. We were able to.
In Examples 15 to 17 in which the content of the alumina fine powder was 70% by mass or less, the bonding strength tended to be higher than the system to which water glass was applied (Examples 1 to 14). When the content of oxide refractory raw material particles exceeds 70% by mass, the viscosity becomes high, and the coating workability (extensibility, etc.) on the metal plate begins to deteriorate, and unevenness occurs on the coated surface. It tends to decline. In addition, when the content of oxide refractory raw material particles is less than 60% by mass, the viscosity becomes low, and the coating workability (extensibility, etc.) on the metal plate begins to deteriorate, and unevenness occurs on the coated surface. Tends to decrease.
Therefore, when primary aluminum phosphate is applied, the content of the oxide refractory raw material particles is desirably 60% by mass or more and 70% by mass or less. As a result, the content of primary aluminum phosphate is not less than 30% by mass and not more than 40% by mass.

Next, Examples 18 to 20 are examples in which orthophosphoric acid was applied. Since regular phosphoric acid has the same low viscosity (about 48 mPa · s) as primary aluminum phosphate, there is a risk that it will sag downward during application to a metal plate. Refractory raw material particles were included.
As oxide refractory raw material particles, alumina fine powder having a size passing through a sieve having a mesh opening of 0.212 mm was used as in Examples 15 to 17. As a result, when the content of the alumina fine powder was 60% by mass or more and 70% by mass or less, the coating workability was good, the coating film was uniform, and the coating film thickness was about 1-2 mm.
In Examples 18 to 20 in which the content of the alumina fine powder was 70% by mass or less, the bonding strength tended to be higher than the system to which water glass was applied (Examples 1 to 14). As in the case of aluminum, when the content of oxide refractory raw material particles exceeds 70% by mass, the viscosity increases, and the coating workability (extensibility, etc.) to the metal plate begins to deteriorate and unevenness occurs on the coated surface. Therefore, the bonding strength tends to decrease. In addition, when the content of oxide refractory raw material particles is less than 60% by mass, the viscosity becomes low, and the coating workability (extensibility, etc.) on the metal plate begins to deteriorate, and unevenness occurs on the coated surface. Tends to decrease.
Therefore, even when orthophosphoric acid is applied, the content of oxide refractory raw material particles is preferably 60% by mass or more and 70% by mass or less. As a result, the content of orthophosphoric acid is 30% by mass or more and 40% by mass or less.

  The confirmation (pull-out test) with the actual machine showed that Comparative Example 1, which is a prior art without an adhesive layer, could not pull out the outer refractory layer (castable refractory) together with the gas blowing plug ( Conceptually refer to FIG. 3), except for Examples 7, 8, 13, and 14 which were not used for confirmation with the actual machine, all of the examples together with the gas blowing plugs had a peripheral refractory layer (castable refractory) ) Could be pulled out (conceptually see FIG. 2).

1 Breathable refractory layer (porous refractory layer)
2 Metal plate (metal case)
3 Peripheral refractory layer (dense refractory layer, castable refractory layer)
4 Adhesive layer (silicate-containing layer)
5 Gas introduction pipe 6 Tuyere

Claims (12)

  In a gas blowing plug including a metal plate at a boundary portion between refractory layers, the metal plate and a dense refractory layer (hereinafter referred to as an “outer refractory layer”) on the outer peripheral side of the metal plate. A gas blowing plug including a layer having a function of bonding a metal plate and the outer peripheral refractory layer (hereinafter referred to as an “adhesion layer”).   The plug for gas blowing according to claim 1 in which said adhesion layer contains silicate.   The plug for gas blowing according to claim 2, wherein the silicate is derived from water glass.   The adhesive layer contains 10% by mass or less in total of at least one kind of refractory raw material particles of alumina, alumina-silica, zircon, spinel or silicic acid having a particle size of 0.5 mm or less. The gas blowing plug according to any one of claims 1 to 3.   The plug for gas blowing according to claim 1 in which said adhesion layer contains orthophosphoric acid or phosphate.   The adhesive layer contains a total of 60% by mass or more and 70% by mass or less of at least one kind of refractory raw material particles of alumina, alumina-silica, zircon, spinel, or silicic acid having a particle size of 0.5 mm or less. The gas blowing plug according to claim 5.   The plug for gas blowing according to any one of claims 1 to 6, wherein the maximum thickness of the adhesive layer is 0.5 mm or more and 2 mm or less.   The plug for gas blowing according to any one of claims 1 to 7, wherein at least a part of the adhesive layer includes a portion joined to the outer peripheral refractory layer by unevenness.   The method for manufacturing a gas blowing plug according to any one of claims 1 to 8, wherein a breathable refractory is disposed on an inner peripheral side of the metal plate, and silicic acid is disposed on an outer peripheral side of the metal plate. Forming a bonding layer with a material containing salt, orthophosphoric acid or phosphate, and setting a peripheral refractory layer so as to cover the bonding layer without passing through a heat treatment step after the formation of the bonding layer , Manufacturing method of plug for gas blowing.   The method for manufacturing a gas blowing plug according to claim 9, wherein the material containing silicate is water glass. The water glass has a SiO ₂ / R ₂ O (R: alkali metal) molar ratio of 2.35 to 3.35, orthophosphoric acid is orthophosphoric acid of H ₃ PO ₄ , and phosphate is molar ratios shown in _{al 2 O 3 / P 2 O} 5 is 0.25 to 0.40, manufacturing method for a gas blowing plug according to claim 10.   The process for installing the outer peripheral refractory layer includes pouring, indenting, or spraying an amorphous refractory, and manufacturing a plug for gas blowing according to any one of claims 9 to 11. Method.