JP7347393B2 - Shell structure of molten metal storage container and molten metal storage container - Google Patents

Description

The present invention relates to a shell structure of a molten metal container and a molten metal container.

In steel works, iron mixer cars, blast furnace ladle, hot metal charging ladle, molten steel ladle, tundish, etc. are made up of an iron shell that forms a container-shaped outer shell and a refractory that lines the inner surface of the iron shell. A molten metal container is used. The refractories lined in these molten metal containers include shaped refractories and monolithic refractories, but mortar (a type of monolithic refractory) used as a joint material during the construction of shaped refractories, and pour-in construction The monolithic refractories used contain moisture and volatile matter. In order to remove these moisture and volatile components, the refractory after construction is heated to remove water and dry. Through this heating and drying, moisture and volatile matter are dissipated into the atmosphere as gas, but in order to secure a discharge path for the generated gas, the iron shell forming the outer shell of the molten metal storage container is As shown in , a large number of gas vent holes (also referred to as ``steam vent holes'' or ``steam holes'') are installed through the steel shell.

However, when the refractory is damaged by melting and the molten metal penetrates into the steel shell, the above-mentioned gas vent hole can become a path for the molten metal to flow out of the container. On the other hand, Patent Document 2 discloses a molten metal storage container in which a permanently stretched refractory is constructed of a shaped refractory, and a gas vent hole is installed for venting gas generated during heating and drying of the refractory. Disclosed is a molten metal storage container characterized in that the installation position of the gas vent hole and the joint of the permanent refractory do not match but are shifted. According to this technology, the installation position of the gas vent hole and the joint of the permanent refractory are not aligned, but are shifted, so if molten metal flows through the joint of the permanent refractory and reaches the position of the steel skin. However, the inflowing molten metal is cooled and solidified by the iron shell before reaching the location where the gas vent hole is installed. Therefore, Patent Document 2 states that it is possible to prevent the problem of molten metal flowing out from the gas vent hole.

Japanese Patent Application Publication No. 3-217791 Japanese Patent Application Publication No. 2007-30020

Edited by the Iron and Steel Institute of Japan: 5th edition Steel Handbook Volume 1 Pigmaking/Steelmaking

However, in recent years, in order to suppress the temperature drop of the molten metal contained therein, efforts have been made to improve the insulation properties of the molten metal storage container, such as installing refractories with low thermal conductivity on the permanent refractories. (Non-patent Document 1). Therefore, even if the technology described in Patent Document 2 is applied, the molten metal flowing through the joints of the permanently stretched refractory will reach the steel skin with a smaller temperature drop than before. ing. As a result, even though the molten metal is cooled by the iron shell, it does not solidify, causing problems such as it flowing out from the gas vent holes.
When a problem arises in which molten metal flows out of the gas vent holes, countermeasures are taken to reduce the number of gas vent holes based on experience, but if the number of gas vent holes is reduced too much, the refractory may become deformed due to the pressure of volatile matter. In some cases, the volatile components and the refractory may cause a chemical reaction, and the integrity of the refractory may be impaired.

Therefore, the present invention has been made with attention to the above-mentioned problems, and provides an iron shell structure of a molten metal storage container and a molten metal storage container that can suppress the outflow of molten metal from a gas vent hole. It is intended to.

According to one aspect of the present invention, a molten metal storage container comprising an iron shell forming a container-shaped outer shell and one or more refractory layers lined on the inner surface of the iron shell. The shell structure has one or more gas vent holes provided through the steel shell in the thickness direction of the steel shell, and the penetration depth of the gas vent hole is equal to or greater than the gas vent hole. Provided is a shell structure for a molten metal containment vessel that is at least 2.5 times the diameter of the molten metal container.

According to one aspect of the present invention, the steel shell includes a container-shaped outer shell and one or more refractory layers lined on the inner surface of the steel shell. One or more gas vent holes are provided to penetrate the steel skin in the thickness direction of the steel skin, and the penetration depth of the gas vent hole is 2.5 times the diameter of the gas vent hole. The above-mentioned molten metal storage container is provided.

According to one aspect of the present invention, there is provided a shell structure of a molten metal storage container and a molten metal storage container that can suppress the outflow of molten metal from a gas vent hole.

FIG. 1 is a partial cross-sectional view showing a molten metal storage container according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the structure of the steel shell of the molten metal storage container, in which (A) is a view of the steel shell viewed from the outside, and (B) is a view taken along the line II in FIG. 2(A). It is a schematic diagram showing the mechanism of steel leakage due to damage to the refractory layer. It is a graph showing the occurrence of steel leakage under conditions where the penetration depth and diameter of the gas vent hole are changed. FIG. 5 is a schematic diagram showing the structure of the steel shell of a molten metal storage container when a convex portion is provided on the steel shell, (A) is a view of the steel shell viewed from the outside, and (B) is a diagram similar to that of FIG. 5(A). It is a view taken along the line II-II.

The following detailed description describes embodiments of the invention with reference to the drawings. In the description of the drawings, the same or similar parts are given the same or similar symbols, and overlapping explanations are omitted. Each drawing is schematic and may differ from the actual drawing. In addition, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention. It is not specific to the following. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

<Molten metal storage container and iron skin structure of the molten metal storage container>
The molten metal storage container 1 and the iron shell structure of the molten metal storage container 1 according to an embodiment of the present invention will be described. The molten metal storage container 1 is a container for storing molten metal such as hot metal or molten steel, such as a pig iron mixer car, a blast furnace pot, a hot metal charging pot, a molten steel ladle, or a tundish. 2 and a refractory layer 3 lined on the inner surface of the iron skin 2. In this embodiment, as an example, it is assumed in FIG. 1 that the molten metal storage container 1 is a molten steel ladle. In the example shown in FIG. 1, the refractory layer 3 on the inner surface of the iron shell 2 includes a permanent refractory layer 31 made of refractory bricks, and a monolithic refractory layer and refractory bricks located inside the permanent refractory layer 31. A workpiece refractory layer 32 is lined therewith. In addition, in the work refractory layer 32, the refractory brick is formed above the monolithic refractory.

As shown in FIGS. 2 and 3, the steel shell 2 is provided with a plurality of gas vent holes 21 that penetrate the steel shell 2 in the thickness direction of the steel shell 2. The length of the gas vent hole 21 in the thickness direction of the iron skin 2 is referred to as the penetration depth L (mm). Further, the gas vent hole 21 is a hole having a circular cross-sectional shape perpendicular to the depth direction, and has a diameter of D ₁ (mm).
The penetration depth L of the gas vent hole 21 is at least 2.5 times the diameter _D1 . Here, the present inventors have discovered that the molten metal that has penetrated into the refractory layer and reached the gas vent hole 21 on the inner surface of the steel shell 2 is cooled and solidified within the gas vent hole. We conducted extensive research with the aim of preventing gas from leaking out of the gas vent holes. Figure 3 shows the mechanism of steel leakage due to damage to the refractory layer. In the molten metal storage container 1 such as a ladle, if the workpiece refractory layer 32 is damaged (FIG. 3(A) → FIG. 3(B)), the permanent refractory layer 31 and the molten steel 4 that is the molten metal may come into contact with each other. It becomes a state where If the use continues in this state, the molten steel 4 will infiltrate into the permanent refractory layer 31 through the joints of the permanent refractory layer 31, and steel leakage will occur where the molten steel 4 flows out from the gas vent holes 21 (Fig. 3(C)).

With respect to such outflow of molten metal, the present inventors focused on the relationship between the penetration depth L of the gas vent hole 21 and the diameter _D1 . FIG. 4 shows the results of an investigation into the occurrence of steel leakage under conditions where the penetration depth L and diameter _D1 of the gas vent hole 21 were varied. In Figure 4, "○" indicates a condition where steel leakage did not occur, "△" indicates a condition where steel leakage did not occur and explosion of the refractory or gas vent hole blockage due to dust occurred, and "×" indicates a condition where leakage did not occur. The conditions under which steel was generated are shown below. As shown in FIG. 4, it was confirmed that occurrence of steel leakage could be suppressed by setting the penetration depth L of the gas vent hole 21 to 2.5 times or more the diameter _D1 . This means that the degree of superheating (actual temperature relative to the liquidus temperature) of the hot metal and molten steel that reaches the skin 2 is approximately 20°C, and considering the specific heat of the molten iron and molten steel that has reached the skin, the temperature is _2.5 times the diameter D1. This is because with the above penetration depth L, it was possible to absorb the heating degree of hot metal and molten steel, cool and solidify it, and stop steel leakage and pig iron leakage (leakage of hot metal).

Further, although there is no particular upper limit to the penetration depth L of the gas vent hole 21, it is more preferable that the penetration depth L does not exceed 4.0 times the diameter _D1 of the gas vent hole 21. In order to increase the penetration depth L of the gas vent hole 21, it is necessary to increase the thickness of the iron skin 2 at the portion where the gas vent hole 21 is provided. However, if the penetration depth L of the gas venting hole 21 exceeds 4.0 times the diameter _D1 of the gas venting hole 21, the thickness of the iron skin 2 will increase, so that protrusions will be formed on the outer surface of the container, and the protrusions will be long. This is because there will be more base metal adhering to the surface of the container shell. Moreover, the weight of the container becomes heavy, which is not preferable.
Further, the diameter _D1 of the gas vent hole 21 is preferably 5 mm or more and 30 mm or less. If the diameter _D1 is less than 5 mm, the gas vent hole may be blocked and the refractory layer 3 may explode during drying. On the other hand, when the diameter _D1 exceeds 30 mm, there is no difference in the explosion prevention effect during drying of the refractory layer 3, and the contact area of the molten metal that has entered the hole becomes smaller.

Furthermore, the steel shell structure of the molten metal storage container 1 according to this embodiment is not limited to the example shown in FIG. 2. If the thickness of the existing steel shell 2 of the molten metal storage container 1 is thin and the penetration depth L of the gas vent hole 21 cannot be made more than 2.5 times the diameter _D1 of the gas vent hole 21, as shown in FIG. As shown, the penetration depth L of the gas vent hole may be increased by providing a convex portion 22 on the outer surface of the iron skin 2 with an increased thickness of the iron skin 2. The convex portion 22 can be formed by attaching a member made of the same material as the iron skin to the outer surface of the iron skin 2 or by applying build-up. As shown in FIG. 5, if the convex part 22 has a cylindrical shape with the thickness direction of the steel shell 2 as its axial direction, it will be easier to install, and the molten metal that has entered the gas vent hole 21 will be uniformly heat removed. preferable. In addition, when the convex part 22 is provided, the gas vent hole 21 is provided penetrating the steel shell 2 in the thickness direction of the steel shell 2 from the inner surface side of the steel shell 2 to the outer surface side of the steel shell of the convex part 22. In other words, the penetration depth L is the sum of the thickness of the iron skin 2 (the depth of the hole in the iron skin 2) and the depth of the hole in the convex portion 22. Further, when the convex portion 22 is cylindrical, the gas vent hole 21 is formed coaxially with the convex portion 22 in the thickness direction of the steel sheath 2 from the inner surface of the iron sheath 2 to the outer surface of the convex portion 22. It is installed through the Furthermore, when the convex portion 22 is cylindrical, it is desirable that the outer diameter D ₂ of the cylinder is at least twice the diameter D ₁ of the gas vent hole 21 . By making the outer diameter D ₂ of the cylinder at least twice the diameter D ₁ of the gas vent hole 21 , a sufficient heat capacity of the convex portion 22 necessary for solidifying the molten metal that has entered the gas vent hole 21 is ensured. Although there is no particular upper limit for the outer diameter D ₂ , even if the outer diameter D ₂ is increased to more than four times the diameter D 1 , the rate of heat conduction within the convex portion 22 is rate-determining and the solidification effect of the molten metal that has entered the gas vent hole 21 is reduced. Since it reaches a plateau, a more preferable range is within 4 times the diameter _D1 .

<Modified example>
Although the invention has been described above with reference to particular embodiments, it is not intended that the invention be limited by these descriptions. Other embodiments of the invention, including various modifications, will be apparent to those skilled in the art from reading the description of the invention. Therefore, the embodiments of the invention described in the claims should be understood to include embodiments including any of these modifications described herein alone or in combination.

For example, in the above embodiment, the refractory layer 3 is two layers consisting of the permanent refractory layer 31 and the workpiece refractory layer 32, but the present invention is not limited to this example. The number of refractory layers 3 may be one or more, and is appropriately set depending on the type and use of the molten metal container 1. Furthermore, the type of refractory to be used for the refractory layer 3 is also appropriately set depending on the type of the molten metal storage container 1.

Further, in the above embodiment, a plurality of gas vent holes 21 are provided, but the present invention is not limited to such an example. The number of gas vent holes 21 may be one or more, and is appropriately selected depending on the shape and dimensions of the molten metal container 1. Furthermore, in the case where a plurality of gas vent holes 21 are provided, only the gas vent holes 21 where leakage is a concern may have a structure similar to that of the above embodiment, instead of all the gas vent holes 21.
Further, in the above embodiment, an example in which the molten metal is hot metal or molten steel has been described, but the present invention is not limited to such an example. As long as the molten metal storage container 1 has an iron shell 2 and a refractory layer 3, it can be applied to molten metals other than iron.

<Effects of embodiment>
(1) The shell structure of the molten metal storage container 1 according to one aspect of the present invention includes a steel shell 2 forming an outer shell in the shape of a container, and one or more layers lining the inner surface of the steel shell 2. A steel shell structure of a molten metal storage container 1 comprising a refractory layer 3 and one or more gas vent holes 21 provided through the steel shell 2 in the thickness direction of the steel shell 2. However, the penetration depth L of the gas vent hole 21 is at least 2.5 times the diameter _D1 of the gas vent hole 21.
According to the configuration (1) above, even if molten metal intrudes into the refractory layer 3 due to damage to the refractory and reaches the gas vent hole 21 on the inner surface of the steel shell 2, the molten metal will vent. When passing through the hole 21, it is cooled and solidified. This can reduce the occurrence of troubles in which molten metal flows out from the gas vent hole 21.

(2) In the configuration of (1) above, the diameter _D1 is 5 mm or more and 30 mm or less.
According to the configuration (2) above, degassing accompanying heating and drying of the refractory can be appropriately performed.
(3) In the configuration of (1) or (2) above, the outer surface of the iron skin 2 has a protrusion 22 that is made thicker, and the gas vent hole 21 is a protrusion from the inner surface of the iron skin 2. It is provided extending to the outer surface of the steel shell of the portion 22 and penetrating the steel shell 2 in the thickness direction.
According to the configuration (3) above, even when the thickness of the iron skin 2 is thin, the same effect as the configuration (1) above can be obtained.

(4) In the configuration of (3) above, the convex portion 22 has a cylindrical shape with the thickness direction in the axial direction, and the gas vent hole 21 extends from the inner surface of the steel shell 2 to the outer surface of the steel shell of the convex portion 22. , is provided coaxially with the convex part 22 in the thickness direction, penetrating the iron skin 2, and the outer diameter _D2 of the convex part 22 is more than twice the diameter _D1 of the gas vent hole 21.
According to the configuration (4) above, when the convex portion 22 is provided, the heat capacity of the convex portion 22 necessary for solidifying the molten metal that has entered the gas vent hole 21 is sufficiently secured, so that the molten metal is Outflow can be suppressed more reliably.

(5) A molten metal storage container according to one aspect of the present invention includes a steel shell forming a container-shaped outer shell, and one or more refractory layers lined on the inner surface of the steel shell. The iron skin has one or more gas vent holes provided through the iron skin in the thickness direction of the iron skin, and the penetration depth of the gas vent hole is 2.5 times the diameter of the gas vent hole. That's more than double that.
According to the configuration (5) above, the same effect as in (1) above can be obtained.

(6) In the configuration of (5) above, the diameter is 5 mm or more and 30 mm or less.
According to the configuration (6) above, the same effect as in (2) above can be obtained.
(7) In the structure of (5) or (6) above, the iron skin has a protrusion on the outer surface that increases the thickness of the iron skin, and the gas vent hole is formed from the inner surface of the iron skin at the protrusion. It is installed extending through the steel shell in the thickness direction towards the outer surface.
According to the configuration (7) above, the same effect as in (3) above can be obtained.

(8) In the configuration of (7) above, the convex part has a cylindrical shape with the thickness direction in the axial direction, and the gas vent hole extends in the thickness direction from the inner surface of the steel shell to the outer surface of the steel shell of the convex part. It is provided coaxially with the convex part and penetrates through the iron skin, and the outer diameter of the convex part is more than twice the diameter of the gas vent hole.
According to the configuration (8) above, the same effect as in (4) above can be obtained.
(9) In any one of the configurations (5) to (8) above, the molten metal storage container is a pig iron mixing car, a blast furnace ladle, a hot metal charging ladle, a molten steel ladle, or a tundish.

The present inventors actually used the molten metal storage container 1 according to the above embodiment in a molten steel ladle having an internal capacity of 226 tons. The molten steel ladle receives molten steel that has been subjected to converter refining and tapped from the converter. The temperature of the molten steel is 1650°C or higher. Next, the molten steel held in the molten steel ladle is subjected to a secondary refining process. Secondary refining treatments include vacuum degassing refining treatment using RH vacuum degassing equipment and gas bubbling treatment. The molten steel that has been subjected to the secondary refining process is held in this molten steel ladle and transported to a continuous casting machine. In a continuous casting machine, molten steel is poured from a molten steel ladle into a tundish. The empty molten steel ladle is used for receiving the next steel. In this way, more than 50 treatments were performed without refractory repair.
As a result, although there were approximately three cases per year in which molten steel reached the steel shell 2, it was confirmed that none of them resulted in steel leakage problems.

1 Molten metal storage container 2 Iron shell 21 Gas vent hole 22 Convex portion 3 Refractory layer 31 Permanent refractory layer 32 Work refractory layer 4 Molten steel (molten metal)

Claims (5)

An iron shell structure for a molten metal storage container, comprising an iron shell forming a container-shaped outer shell, and one or more refractory layers lined on the inner surface of the iron shell,
having one or more gas vent holes provided through the iron sheath in the thickness direction of the iron sheath,
The penetration depth of the gas vent hole is 2.5 times or more the diameter of the gas vent hole,
The outer surface of the iron skin has a convex portion that increases the thickness of the iron skin,
The gas vent hole is provided penetrating the steel shell in the thickness direction from the inner surface of the steel shell to the outer surface of the convex portion,
The convex portion has a cylindrical shape with the thickness direction being in the axial direction,
The gas vent hole is provided coaxially with the convex portion and penetrating the steel sheath in the thickness direction from the inner surface of the iron sheath to the outer surface of the convex portion,
The outer diameter of the convex portion is at least twice the diameter of the gas vent hole . The iron skin structure for a molten metal storage container according to claim 1, wherein the diameter is 5 mm or more and 30 mm or less. The iron skin has a container-shaped outer shell, and one or more refractory layers lined on the inner surface of the iron skin. having one or more gas vent holes provided through the
The penetration depth of the gas vent hole is 2.5 times or more the diameter of the gas vent hole,
The iron skin has a protrusion on the outer surface that increases the thickness of the iron skin,
The gas vent hole is provided penetrating the steel shell in the thickness direction from the inner surface of the steel shell to the outer surface of the convex portion,
The convex portion has a cylindrical shape with the thickness direction being in the axial direction,
The gas vent hole is provided coaxially with the convex portion and penetrating the steel sheath in the thickness direction from the inner surface of the iron sheath to the outer surface of the convex portion,
In the molten metal storage container , the outer diameter of the convex portion is at least twice the diameter of the gas vent hole . The molten metal storage container according to claim 3 , wherein the diameter is 5 mm or more and 30 mm or less. The molten metal storage container according to claim 3 or 4, wherein the molten metal storage container is a pig iron mixer, a blast furnace ladle, a hot metal charging ladle, a molten steel ladle, or a tundish.

Images