KR101631400B1 - Molten steel container - Google Patents

Abstract

A molten steel container for retaining molten steel having a carbon content of 2 mass% or less, wherein the molten steel vessel has a refractory lining structure having an iron core, a permanent refractory layer and a work refractory layer in order from the outside, A bed portion which is divided into a steel bath portion contacting the molten steel and a slag line portion contacting the slag on the molten steel, the bed portion being disposed at a bottom portion of the molten steel vessel, and the bed portion disposed at a side portion of the molten steel vessel, And a sidewall portion connected to the slag line portion. At least a heat insulating material having a thermal conductivity of 0.1 W / (m · K) or less and a thickness of 1 mm or more is applied to at least the side wall portion of the side wall portion, Wherein the molten steel is a shaped refractory material containing no silicon, at least magnesium oxide, and a carbon content of 1.5 to 11 mass%.

Description

[0001] MOLTEN STEEL CONTAINER [0002]

The present invention relates to a molten steel vessel.

Patent Document 1 discloses a refractory lining structure of a container for holding a molten iron (hereinafter referred to as a "refractory lining structure") having a steel shell, a permanent refractory layer and a work refractory layer sequentially from the outside (claim 1) "A heat insulating material is disposed between the metal foil and the permanent refractory layer" (claim 6).

Specifically, Patent Document 1 discloses that the work refractory layer is made of a material selected from the group consisting of Al ₂ O ₃ -SiC-C materials ([0038], [0060] to [0064] ([Claims 5] and [0060]).

Patent Document 1: Japanese Patent Application Laid-Open No. 2011-145056

Steel having a carbon content of 2% by mass or less has a melting point of 1400 to 1540 캜 and a high temperature relative to the melting point of the molten iron (about 1200 캜), so that transportation, retention and treatment of molten steel Lt; RTI ID = 0.0 > 1640 C. < / RTI >

Therefore, containers (molten steel containers) for holding and retaining molten steel are required to have higher corrosion resistance and heat insulating property than containers for holding molten iron.

The present inventors have found that when the refractory lining structure disclosed in Patent Document 1 is applied to a molten steel vessel, sufficient corrosion resistance and heat insulating property can not be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a molten steel vessel excellent in both corrosion resistance and heat insulation.

The inventors of the present invention have made intensive investigations in order to achieve the above object. As a result, it has been found that, in the refractory lining structure of a molten steel vessel provided with a heat insulating material, by using a specific refractory as a work refractory at a predetermined site, And the present invention has been accomplished.

That is, the present invention provides the following (1) to (3).

(1) A molten steel container for retaining molten steel having a carbon content of 2 mass% or less, wherein the molten steel vessel has a refractory lining structure having an iron core, a permanent refractory layer and a work refractory layer in order from the outside, The work refractory layer is divided into a steel bath section (steel bath section) contacting the molten steel and a slag line section contacting the slag on the molten steel. The inferior heating section and the bed section (m < * > K (m < 2 > / K)) at a side of at least the side of the sidewall portion, the sidewall being divided into a bed part and a slag line part, ), And the work refractory constituting the side wall portion contains at least magnesium oxide, does not contain silicon carbide, and has a carbon content of 1.5 to 11 The percent by weight refractory shaping, the molten steel vessel.

(2) The molten steel vessel according to the above (1), wherein the work refractory constituting the slag line portion contains at least magnesium oxide and the carbon content is not less than 10 mass% and not more than 18 mass%.

(3) The molten steel vessel according to the above (1) or (2), wherein the installation position of the heat insulating material is between the permanent refractory layers provided between the iron core and the permanent refractory layer or between the permanent refractory layers.

According to the present invention, it is possible to provide a molten steel vessel excellent in both corrosion resistance and heat insulating property.

1 is a cross-sectional view schematically showing an example of a molten steel vessel 1;
Fig. 2 is a test result showing the depth of penetration of the slag component into the amorphous refractory. Fig.
3 is a graph showing the relationship between the carbon content and the depth of the slag infiltration.
4 is a graph showing the relationship between the carbon content and the thermal conductivity.

1 is a cross-sectional view schematically showing an example of a molten steel vessel 1. As shown in Fig. The molten steel vessel 1 is also called a molten steel ladle, for example, and holds molten steel 61 therein. Molten steel 61 is converted by decarbonization of molten iron in a converter (not shown), and its carbon content is 2 mass% or less. The carbon concentration of the general steel is about 0.002 to 0.3 mass%, and it is preferable to apply it to the molten steel vessel of such steel.

In the molten steel vessel 1, a secondary refining treatment is performed in which impurities are removed from the molten steel 61 or an additive element is added. Examples of the main secondary refining include RH (Ruhrstahl-Heraeus), Ladle Furnace (LF), and Vacuum Oxygen Decarburization (VOD). The secondary refined molten steel 61 is transported by the molten steel vessel 1 and is supplied to the continuous casting process.

The molten steel vessel 1 shown in Fig. 1 holds the molten steel 61 received from the converter and the slag 62 floats on the molten steel surface of the molten steel 61.

The refractory lining structure provided in the molten steel vessel 1 basically has the iron foil 2, the permanent refractory layer 3 and the work refractory layer 4 in order from the outside.

The iron foil 2 is an outermost layer of the molten steel vessel 1 and is a steel structure supporting the refractory.

The permanent refractory layer 3 is also referred to as safety lining as a brick layer which is applied to secure safety so that the molten steel 61 is not leaked even when (part of) the work refractory layer 4 Or may be formed in two layers.

As the refractory (also referred to as " permanent refractory ") constituting the permanent refractory layer 3, a molded refractory (molded brick) or a monolithic refractory is used. Specifically, pyromite bricks are used.

The work refractory layer 4 is a refractory layer directly contacting the molten steel 61 and is a layer forming the contact surface (movable surface) with the molten steel 61 and the slag 62.

As the refractory (also referred to as "work refractory") constituting the work refractory layer 4, a molded refractory (molded brick) or a monolithic refractory is used.

The work refractory layer 4 is mainly divided into a steel bath portion 41 contacting the molten steel 61 held in the molten steel vessel 1 and a slag line portion 42 contacting the slag 62.

The slag line portion 42 does not strictly coincide with the position of the slag 62 even if the slag line portion 42 is in contact with the slag 62. That is, the lower limit of the slag line portion 42 is lower than the bottom position of the slag 62 by about 1/10 of the entire height of the molten steel vessel 1. This is because the slag 62 is always in contact with the slag line portion 42 even when the height position of the slag 62 varies during the drastic processing of secondary refining such as LF and VOD.

The steel bath portion 41 also includes a bed portion 411 disposed at the bottom of the molten steel vessel 1 and a bed portion 411 disposed at the side portion of the molten steel vessel 1 and including a bed portion 411 and a slag line portion 42 And a side wall portion 412 connected to the side wall portion 412.

In the work refractory layer 4, there may be a case where the portion contacting the molten steel 61 and the slag 62 fluctuates, for example, during the taking-in and outgoing steel. However, And the "slag line portion 42" refer to a state in which the river from the converter or the like is finished and the molten steel 61 is held (including the state during transportation and the state where various treatments such as secondary refining are performed) And means the concept of a normal operating condition.

The work refractory constituting the work refractory layer 4 includes at least the work refractory constituting the slag line portion 42, the work refractory constituting the side wall portion 412 of the steel bath portion 41, And the workpiece refractories constituting the bed portion 411 of the first and second heat exchangers 41 and 41, which are different from each other. Details of the work refractory layer 4 (work refractory) will be described later.

Next, the heat insulating material 5 will be described. The heat insulating material 5 is a material exhibiting a heat insulating function, and examples of the material include SiO ₂ and Al ₂ O ₃ . As the heat insulating material 5, it is preferable to use a material having a compressive strength higher than the static pressure. For example, a heat insulating material to which silicon carbide (SiC) and titanium oxide are added may be used, ) Or the like may be mixed to secure the strength.

The installation position of the heat insulating material 5 is not particularly limited as long as the heat insulating material 5 can be operated at a low temperature and the heat insulating performance can be exhibited for a long period of time (for example, 2 years or more) ) And the permanent refractory layer (3).

When the permanent refractory layer 3 is provided in two layers, it may be applied between the two layers. However, even if the temperature of the heat insulating material 5 is lower than the heat-resistant temperature, deterioration such as shrinkage is confirmed There is a case. Even in this case, since the deterioration degree differs depending on the operating temperature and the operating time, the heat insulating performance is generally exhibited for about one year. Therefore, in the first or second inspection performed in about one to two years after the start of use, It is preferable to dismantle the refractory layer 3 to grasp the deterioration behavior of the heat insulating material 5. [

Hereinafter, a case in which the heat insulating material 5 is applied between the iron foil 2 and the permanent refractory layer 3 is described as an example, but the present invention is not limited thereto.

The heat insulating material 5 is applied at least on the side of the side 2 of the side wall 412 (also referred to as " back side "). Naturally, the heat insulating material 5 may be applied to the back side of the entire work refractory layer 4 including the bed portion 411 and the slag line portion 42 (see Fig. 1).

The thermal conductivity of the heat insulating material 5 is not more than 0.1 W / (mK) and not more than 0.06 W / (mK) because it can suppress the temperature decrease of the molten steel 61 held as far as possible It is more preferable because the thermal resistance can be almost doubled by a thickness of 3 mm.

The greater the thickness of the heat insulating material 5, the more the thermal resistance can be increased. If the thickness is extremely thin, the workability is poor and the thermal resistance tends to become uneven. Insulation, however, is generally poor in strength and fire resistance than permanent refractories. Therefore, when the molten steel locally reaches the heat insulating material because the work refractory is abnormally worn out, the heat insulating material will melt in a short time. At this time, if the thickness of the heat insulation material is 5 mm or less, molten steel does not leak widely to the heat insulating material portion, and the molten steel does not enter the gap of the refractory material. Therefore, the thickness of the heat insulating material 5 is preferably 5 mm or less.

As the heat insulating material 5, a commercially available product can be used. For example, a microporous material having a heat resistance temperature of 1100 캜, a thickness of 3 mm and a thermal conductivity of 0.02 to 0.08 W / (mK) Insulation.

As described above, the heat insulating material 5 is applied to the back side of at least the side wall portion 412. The method of applying the heat insulating material 5 to the back surface side of the work refractory layer 4 is advantageous in that a higher heat insulating effect can be used because the fire resistance required for the heat insulating material 5 may be low.

On the other hand, if the work refractory layer 4 is insulated from the back surface side, the cost of the work is raised due to the temperature rise. Therefore, if the work refractory layer 4 having high resistance to temperature rise is not used, In addition, there is a case in which the thickness is decreased rapidly due to hand gaps and sufficient heat insulating property can not be obtained.

Like the permanent refractory layer 3, a molded refractory (molded brick) and a monolithic refractory (castable) are known as the work refractory constituting the work refractory layer 4. Unshaped refractories are widely used in the steel industry as ladle ladles for ease of construction. The unshaped refractory is generally formed by adding a certain amount of water to a mixture of powders or particles of a high-melting point substance such as aluminum oxide and magnesium oxide to fluidize the mixture and pour it between the molten steel container 1 and a mold (not shown) So that it is attached to the inside of the molten steel vessel 1. Therefore, the porosity of a monolithic refractory is larger than that of a pressure-molded orthopedic refractory.

Therefore, the inventors of the present invention investigated the deterioration worsted mechanism for the work refractory used for the side wall portion 412 where the heat insulating material 5 is disposed on the back side. The work refractory is also brought into contact with the slag at the time of discharging the molten steel in the side wall portion and the bed portion other than the slag line portion. Therefore, first, the present inventors paid attention to the fact that the influence of the slag in the hand can not be neglected, and examined the depth of penetration of the slag component into the amorphous refractory.

2 is a test result showing the depth of penetration of the slag component into the monolithic refractory. In Fig. 2, the left side shows the case where the back side of the monolithic refractory is not insulated, and the right side shows the case where the side is adiabated.

As shown in Fig. 2, the penetration depth of the slag component was about 40% intensified by the heat insulation. It was found that the infiltration of the slag component changes the mineral structure of the refractory material, and deteriorates the loss or damage due to the decrease of the melting point and the expansion ratio. From this, the present inventors thought that it is effective to prevent the infiltration of the slag component in order to improve the corrosion resistance of the work refractory layer 4 in adhering the back side of the work refractory layer 4.

In order to prevent the infiltration of the slag component, densification of the refractory is effective. Therefore, the present inventors conducted a test for insulating the back surface using a commercially available dense-type refractory made of a dense material, and found that the slag infiltration was reduced by about 20%, but was 10% worse as compared with the case without heat insulation.

The present inventors sought a method of suppressing slag infiltration and focused on carbon. It is known that carbon has an effect of preventing infiltration due to a large contact angle with slag.

On the other hand, however, it is also known that the thermal conductivity of carbon is as high as several ten times as high as that of refractory components such as aluminum oxide and magnesium oxide, thereby lowering the heat insulating property. In addition, when the low tan steel is dissolved (solvent), the picking up of carbon from the refractory is also concerned.

Therefore, the present inventors have studied the carbon content capable of avoiding such adverse effects while reducing the infiltration of the slag component.

First, the inventors of the present invention investigated the depth of slug penetration when the carbon content was varied by using a monolithic refractory containing carbon. 3 is a graph showing the relationship between the carbon content and the depth of the slag infiltration. In the graph shown in Fig. 3, the abscissa is the carbon content (unit: mass%) and the ordinate is the index (slag infiltration depth index) when the slag infiltration depth at the carbon content of 0.6 mass% is 100. From the graph shown in Fig. 3, it was found that when the carbon content is 1.5% by mass or more, the depth of slag penetration can be reduced by half.

Next, the present inventors investigated the thermal conductivity when the carbon content of the amorphous refractory material was varied. 4 is a graph showing the relationship between the carbon content and the thermal conductivity. In the graph shown in Fig. 4, the horizontal axis is the carbon content (unit: mass%) and the vertical axis is the thermal conductivity (unit: W / (m · K)). From the graph shown in Fig. 4, it is found that the thermal conductivity tends to increase with the increase of the carbon content, but the change of the thermal conductivity is extremely small in the region where the carbon content is 11 mass% or less.

3 and 4, the carbon content of the work refractory constituting the sidewall portion 412 to which the heat insulating material 5 is applied on the back side is set to 1.5 to 11 mass%, whereby the infiltration prevention of the slag component , And the heat insulating property can be highly compatible.

The carbon content of the work refractory constituting the side wall portion 412 is preferably as low as not to be less than 1.5% by mass from the viewpoint of thermal conductivity. However, in a case where the steel is used for refining at a high temperature for a long time such as a special steel, or when the rise and fall of the temperature is severe due to intermittent operation, from the viewpoint of the prevention of the spoilage and the damage, Loses. Specifically, it is preferably 4% by mass or more.

On the other hand, when the carbon content exceeds 11 mass%, the heat insulating effect is lost, so the upper limit of the carbon content is set to 11 mass%. When the low-carbon steel is to be solvent, the carbon content is preferably 7% by mass or less from the viewpoint of reducing the carbon pickup to the molten steel (61).

However, since the carbon has a small specific gravity, it has been considered difficult to apply the carbon in a range of 2 m or more in the depth direction of the molten steel vessel 1, since the uniformity is lost when carbon is mixed in the pouring operation of the amorphous refractory. This problem can be solved by using a press-formed orthopedic refractory before the construction, but the construction of the brick of the orthopedic refractory such as molded bricks and the like is more economical than the infiltration of the irregular refractory It has been considered.

However, the orthopedic refractories were experimentally constructed and disassembled after use, so that foreign matter such as slag and ground metal could be easily separated from the refractory after use. In this way, it was conceived to recycle the refractory after use as a refractory raw material, and the economical effect complementing the defects of the construction economical efficiency was obtained.

In addition, the monolithic refractory tends to absorb moisture from the surrounding atmosphere, and deteriorates if the stock before the construction is stored for a long time. However, it has been found that orthopedic refractories are capable of stocking organs in the long term, and it is possible to select a cheap item from a wide range of remote production sites including overseas.

Thus, as the work refractory constituting the side wall portion 412, it is determined that the fixed refractory is employed in the molten steel vessel 1 by excluding the sticking to the presently mainstream unshaped refractory.

However, for example, as disclosed in Patent Document 1, refractories containing silicon carbide (SiC) such as " Al ₂ O ₃ -SiC-C material " .

However, as described above, the molten steel 61 has a melting point (1400 to 1540 ° C) higher than the melting point of the molten iron (about 1200 ° C) and its transportation, retention and treatment are also performed at a high temperature of 1500 to 1640 ° C .

Therefore, since the work refractory used in the molten steel vessel 1 is required to have higher corrosion resistance, it is not preferable to use a material containing silicon carbide (SiC). This is because SiC is easily dissolved in molten steel having a low carbon content, and dissolution is accelerated as the temperature is higher, as compared with a charcoal containing carbon close to saturation.

Therefore, as the work refractory constituting the side wall portion 412, the above-mentioned content of carbon (C) is contained but silicon carbide (SiC) is not contained and instead, at least a normal refractory material containing magnesium oxide (MgO) . Thereby, even when the molten steel 61 is held, high corrosion resistance is obtained. When magnesium oxide (MgO) is contained in an amount of 5 to 20 mass%, the effect on corrosion resistance is remarkable, and it is preferable that the content of magnesium oxide (MgO) is 5 to 20 mass%. And further preferably 5 to 10% by mass.

The shaped refractory material may contain, in addition to MgO, a refractory component such as aluminum oxide (Al ₂ O ₃ ) or calcium oxide (CaO).

Specific examples of such a typical refractory material include Al ₂ O ₃ -MgO-C brick and MgO-C brick, and not all of them are used as a work refractory of a container for retaining charcoal.

The carbon contained in the work refractory constituting the side wall portion 412 (including the work refractory layer 4) is, for example, graphite, and a specific example thereof is scaly graphite.

As described above, the heat insulating material 5 is applied to the rear surface side of the side wall portion 412, and as the work refractory constituting the side wall portion 412, at least magnesium oxide (SiC) (MgO) and having a carbon content of 1.5 to 11 mass% is used, excellent heat insulation and corrosion resistance can be achieved.

Next, the work refractory constituting the slag line portion 42 will be described. In the case of secondary refining such as LF and VOD, the erosion by the slag 62 is intensified in the case of the slag line portion 42 having a small area in contact with the molten steel 61, It is not always appropriate to apply the work refractory used for the side wall portion 412 because the life is extremely shortened compared with other portions and the operation becomes difficult.

Therefore, it is preferable to use a molded refractory material containing at least magnesium oxide (MgO) and having a carbon content of more than 10 mass% and not more than 18 mass% as the work refractory constituting the slag line portion 42. Specifically, For example, MgO-C bricks and the like can be given. Thus, in the slag line portion 42, the resistance against erosion of the slag 62 is improved, and the corrosion resistance is excellent.

The carbon content of the work refractory (shaped refractory) constituting the slag line portion 42 is more preferably more than 12 mass% and not more than 16 mass%, because the carbonaceous content of the work refractory (shaped refractory) constituting the slag line portion 42 can maintain the constant heat insulating property while allowing better slag erosion resistance .

Next, the work refractory constituting the bed portion 411 will be described. Since the bed portion 411 of the molten steel vessel 1 is embedded with a nozzle (not shown) for allowing the molten steel 61 to flow in and out of the stirring gas and is required to withstand the hands at the time of taking the drink, 412) (for example, about twice as much as the side wall portion 412). Therefore, the heat insulating property is relatively high. Unlike the side wall portion 412, for example, in the bed portion 411, pouring can be facilitated without special equipment for molding and vibrating.

As described above, in the bed portion 411, the effect of using the molded refractory used for the heat insulating material 5 and the side wall portion 412 is relatively small. For this reason, in the bed portion 411, the pouring operation of the generally made monolithic refractory may be performed.

Naturally, this does not exclude the installation of the heat insulating material 5 on the back surface side of the bed portion 411, nor does it deny the use of the molded refractory used for the side wall portion 412.

The work refractory layer 4 above the slag line portion 42 is the easiest part to repair on the way. Therefore, the work refractory constituting the portion is not particularly limited, and for example, a regular refractory material of Al ₂ O ₃ -MgO-C material or MgO-C material, a monolithic refractory material, or an alumina mortar can be used.

The thickness of the work refractory layer 4 is preferably 90 mm or more at any site. This is because, when the remaining thickness of the work refractory is about 30 mm, the risk of dislodging increases. Therefore, before the work refractory is dismantled and repaired beforehand, the thickness of the work refractory initially decreases significantly, Because.

Example

Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to these.

<Inventive Examples 1 to 6, Comparative Examples 1 to 5>

1, a permanent refractory layer 3 (thickness: 50 mm) was formed by using pyroxene bricks as a permanent refractory on the inner side of a ridge 2 (thickness: 30 mm) On the inside of the refractory layer 3, a work refractory layer 4 to be described later was applied.

A sheet-like porous heat insulating material was applied as a heat insulating material 5 between the iron foil 2 and the permanent refractory layer 3, except for a part of the examples. Since the bed portion 411 is thicker than other portions, the heat insulating property is excellent. However, from the viewpoint of the maintenance property of the molten steel vessel 1, it is preferable that the temperature of the outer surface of the iron foil 2 is as small as possible. 411, the heat insulating material 5 was applied.

At this time, the thermal conductivity and the thickness of the heat insulating material 5 were different in each example as shown in Table 1 below. When the heat insulating material 5 is not applied, "-" is shown in the first table below.

In the bed portion 411 of the work refractory layer 4, a work refractory similar to that used for the side wall portion 412 was used. Common to each example was a thickness of 300 mm.

Work as a work refractory material constituting the side wall part 412 of the refractory material layer 4, and except for some examples, and, Al ₂ O ₃ -7 using mass% MgO-C brick, under the carbon (C) content, As shown in Table 1, the examples were different.

In Comparative Examples 1 to 4, Al ₂ O ₃ -SiC-C bricks were used, and the contents of carbon (C) and silicon carbide (SiC) were determined as shown in Table 1 below. In Comparative Example 5, a monolithic refractory material of 90 mass% Al ₂ O ₃ -7 mass% MgO-1 mass% SiO ₂ was used. In the example in which the Al ₂ O ₃ -SiC-C brick is not used, "-" is described as the SiC content in the first table below.

The thickness of the side wall portion 412 is 120 mm, which is common to all the examples.

MgO-C brick was used as the work refractory constituting the slag line portion 42 of the work refractory layer 4, and the carbon (C) content thereof was different in each example as shown in the following Table 1 . The thickness of the slag line portion 42 was set to 120 mm in common with each example.

As the work refractories constituting the upper portion of the work refractory layer 4 above the slag line portion 42, the height was adjusted to be the same level as that of the upper end of the iron plate 2 by using alumina mortar in common with the examples .

<Evaluation>

In each of the examples of the molten steel containers 1, the temperature drop (unit: 占 폚) from the entrance to the molten steel 61 from which the molten steel has been spouted from the converter through the RH treatment to the continuous casting process is measured did. The results are shown in Table 1 below. The lower the amount of decrease in the molten steel temperature, the more excellent the heat insulation property can be obtained.

After the molten steel 61 having a carbon content of 0.1% by mass was taken and subjected to 70 charging treatment at a ratio of 40% of the LF treatment and 60% of the RH treatment, the side wall portion 412 and the slag line portion 42 The average hand mass (the average value of the worn-out thickness, unit: mm) of the work refractories to be constructed was calculated and expressed as an index (a wool index) obtained by dividing the value of Inventive Example 1 by 100. The results are shown in Table 1 below. The lower the wool index, the better the corrosion resistance. For the comparative example in which the wool index of the work refractory constituting the slag line portion 42 was not evaluated, "-" is described as the wool index in the first table below.

From the results shown in the first table, it was found that Inventive Examples 1 to 6 are excellent in both heat insulation and corrosion resistance in Comparative Examples 1 to 5.

In Inventive Examples 1 to 6, Inventive Examples 1 to 5, in which the carbon content was 13 mass%, were larger than those of Inventive Example 6 in which the carbon content of the slag line portion 42 was 9 mass% The corrosion resistance was excellent.

In the above-described Examples 1 to 6, the brick-piling work of the molded refractory (molded brick) was carried out, while in Comparative Example 5, the irrigated refractory was poured and prepared.

As a result, in the case of the present invention, a lot of airborne particles of two persons per day were needed, but since it is a regular refractory material, it was possible to easily separate slag and foreign matter such as ground gold from the refractory material after use. Therefore, the refractory after use is recycled to the refractory raw material, and the disposal cost of the refractory after use becomes less than half. In addition, the regular refractories were able to reduce refractory unit cost by 15% by providing cheap items from China, utilizing the ability to store long-term inventories. As a result, the increase in the cost of brickwork construction has not only increased costs, but also reduced the cost of refractories by 10%.

1 molten steel vessel
2 evil spirits
3 permanent refractory layer
4 work refractory layer
The 41st
411 bed part
412 side wall portion
42 slag line part
5 Insulation
61 molten steel
62 slag

Claims (3)

A molten steel vessel for holding molten steel having a carbon content of 2 mass% or less,
Wherein said molten steel vessel comprises, from the outside, a steel shell, a permanent refractory layer, and a work refractory layer,
Wherein the work refractory layer is divided into a steel bath section (steel bath section) in contact with the molten steel and a slag line section in contact with the slag on the molten steel,
The bed portion is divided into a bed portion disposed at a bottom portion of the molten steel vessel and a side wall portion disposed at a side portion of the molten steel vessel and connected to the bed portion and the slag line portion,
At least a heat insulating material having a thermal conductivity of 0.1 W / (m 占 K) or less and a thickness of 1 mm or more is applied to the side of the side wall,
Wherein the work refractory constituting the side wall portion is a molded refractory material containing no silicon carbide and containing at least 5 to 20 mass% of magnesium oxide and 1.5 to 11 mass% of carbon content. The method according to claim 1,
Wherein the work refractory constituting the slag line portion is at least magnesium oxide and the carbon content is not less than 10 mass% and not more than 18 mass%. The method according to claim 1 or 2,
Wherein the heat insulating material is placed between the permanent refractory layer and the permanent refractory layer or between the permanent refractory layer and the permanent refractory layer.

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