JP7319563B2 - Tuyere member and method of installing tuyere in bottom of molten metal smelting vessel - Google Patents

Description

The present invention relates to a tuyere member and method of installing a tuyere in the bottom of a molten metal refining vessel.

BACKGROUND ART As a vessel for handling molten metal in the steel industry, etc., a refining vessel having a gas blowing tuyere provided at the bottom for stirring and refining the molten metal is widely used. The portion of the interior of the refining vessel that is in contact with the molten metal is generally made of refractory material, and the refractory material is eroded during continued operation of the refining vessel. Since this erosion progresses particularly easily in the vicinity of the tuyeres, it is desired to improve the durability of the tuyeres in particular to extend the life of the tuyeres.

As the tuyere structure, a combination of a plug having a structure in which a thin tube for blowing gas into a refractory is embedded and a surrounding brick installed around the plug is commonly used. In this construction, a plug having a tubular body communicating with the outside of the furnace is fixed to the furnace body, while the surrounding bricks are not fixed. Therefore, joints between the plug and the surrounding bricks and between the surrounding bricks may open due to the agitation of the molten metal, the operation of the furnace itself, and the like. If the joint opens in this manner, molten metal may flow into the joint and cause increased wear of the plug and surrounding bricks.

Therefore, techniques for preventing the opening of the joints at the tuyeres are being studied. For example, International Publication No. 2019/012601 (Patent Literature 1) describes a method of constructing plugs without gaps without using adjustment bricks or the like. According to the technique disclosed in Patent Literature 1, since there is no need to use adjustment bricks or the like, assembling efficiency is improved.

WO2019/012601

However, according to the technique of Patent Document 1, although it is difficult for gaps to occur during construction, the occurrence of gaps during operation could not be sufficiently avoided. In other words, the technique disclosed in Patent Document 1 is insufficient in countermeasures against widening of the gap due to stirring of the molten metal, operation of the furnace itself, and the like. There is also room for improvement in terms of tuyere damage due to expansion of the refractory.

Therefore, there is a demand for a technique that can prevent damage to refractories during operation and extend the life of tuyeres.

A tuyere member according to the present invention is a tuyere member used at the bottom of a molten metal refining vessel, comprising a core portion including a refractory material and capillaries embedded in the refractory material, and the core portion and a plurality of surrounding bricks arranged surrounding the plug, wherein the longitudinal length of the surrounding bricks is equal to the length of the block portion of the plug. The top surface of the surrounding bricks, which has substantially the same length in the longitudinal direction and is the surface exposed inside the molten metal smelting vessel, is substantially rectangular, and the top surface of the surrounding bricks is substantially rectangular. The area is 40% or more and 70% or less of the area of the plug top surface of the plug, which is the surface exposed inside the molten metal refining vessel.

According to these configurations, it is possible to suitably prevent damage to the refractory caused by expansion of the refractory during operation, stirring of the molten metal, movement of the furnace itself, and the like, thereby extending the life of the tuyere.
Moreover, according to this configuration, it is easy to achieve both a long life of the tuyere and good workability .

A tuyere member according to the present invention is a tuyere member used at the bottom of a molten metal refining vessel, comprising a core portion including a refractory material and capillaries embedded in the refractory material, and the core portion and a plurality of surrounding bricks arranged surrounding the plug, wherein the longitudinal length of the surrounding bricks is equal to the length of the block portion of the plug. The top surface of the surrounding bricks, which has substantially the same length in the longitudinal direction and is the surface exposed inside the molten metal smelting vessel, is substantially rectangular, and the top surface of the surrounding bricks is substantially rectangular. The average width in the lateral direction is 20% or more and 50% or less of the average width of the plug top surface of the plug along the direction extending in the lateral direction.

According to these configurations, it is possible to suitably prevent damage to the refractory caused by expansion of the refractory during operation, stirring of the molten metal, movement of the furnace itself, and the like, thereby extending the life of the tuyere.
Moreover, according to this configuration, it is easier to achieve both a long life of the tuyere and good workability .

A method of installing a tuyere in the bottom of a molten metal refining vessel according to the present invention is provided with a core portion including a refractory and capillaries embedded in the refractory and surrounding the core portion. and placing a plurality of perimeter bricks surrounding the plug, wherein the longitudinal length of the perimeter bricks used adjacent to the plug is equal to the length of the plug. The perimeter is substantially the same as the longitudinal length of the block portion of the perimeter, the top surface of the perimeter brick is substantially rectangular, and is the surface positioned exposed inside the molten metal smelting vessel. The top surface of the bricks is substantially rectangular, and the area of the top surface of the surrounding bricks is 40% of the area of the plug top surface of the plug, which is the surface that is exposed to the inside of the molten metal refining vessel. It is characterized by installing tuyeres at the bottom of the molten metal refining vessel, which is not less than 70%.

According to these configurations, it is possible to suitably prevent damage to the refractory caused by expansion of the refractory during operation, stirring of the molten metal, movement of the furnace itself, and the like, thereby extending the life of the tuyere.
Moreover, according to this configuration, it is easy to achieve both a long life of the tuyere and good workability .

A method of installing a tuyere in the bottom of a molten metal refining vessel according to the present invention is provided with a core portion including a refractory and capillaries embedded in the refractory and surrounding the core portion. and placing a plurality of perimeter bricks surrounding the plug, wherein the longitudinal length of the perimeter bricks used adjacent to the plug is equal to the length of the plug. is substantially the same as the length of the block portion in the longitudinal direction, the top surface of the surrounding brick is substantially rectangular, and the average width in the width direction of the top surface of the surrounding brick is equal to the width in the width direction A tuyere is installed at the bottom of the molten metal refining vessel, which is 20% or more and 50% or less of the average width of the plug top surface of the plug along the extending direction.

According to these configurations, it is possible to suitably prevent damage to the refractory caused by expansion of the refractory during operation, stirring of the molten metal, movement of the furnace itself, and the like, thereby extending the life of the tuyere.
Moreover, according to this configuration, it is easier to achieve both a long life of the tuyere and good workability .

Preferred embodiments of the present invention are described below. However, the scope of the present invention is not limited by the preferred embodiments described below.
As one aspect of the tuyere member according to the present invention, when viewed from the inside of the molten metal refining vessel, the top surface of the plug is square, and the length of the long side of the rectangle of the top surface of the surrounding brick is , the four surrounding bricks are longer than one side of the top surface of the plug so that one short side of the rectangle of the top surface of the surrounding brick and one side of the four sides of the top surface of the plug are aligned on the same straight line. surrounds the plug and is arranged such that there is no gap between the surrounding brick and the plug.
According to one aspect of the method for installing a tuyere at the bottom of a molten metal refining vessel according to the present invention, when viewed from the inside of the molten metal refining vessel, the top surface of the plug is square, and the surrounding bricks are The length of the long side of the rectangular top surface is longer than one side of the top surface of the plug, and the step of installing a plurality of the surrounding bricks surrounding the plug includes, when viewed from the inside of the molten metal refining vessel, The plug is surrounded by the four surrounding bricks so that one short side of the rectangular top surface of the surrounding brick and one of the four sides of the top surface of the plug are aligned on the same straight line. It is preferable to include a step of arranging so as not to form a gap with the plug.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments described with reference to the drawings.

It is a longitudinal cross-sectional view around the tuyere member of the electric furnace according to the embodiment. It is the figure which looked at the tuyere member which concerns on embodiment from the inside of the electric furnace. It is a longitudinal cross-sectional view of a tuyere member according to the embodiment. It is a longitudinal cross-sectional view of a tuyere member according to the prior art.

An embodiment of a surrounding brick, a tuyere member, and a method of installing a tuyere on the bottom of a molten metal refining vessel (hereinafter referred to as "installation method") according to the present invention will be described with reference to the drawings. Below, the surrounding bricks 1 (one embodiment of the surrounding bricks according to the present invention) used in the bottom of the electric furnace 100 (which is an example of the molten metal refining vessel), and the surrounding bricks 1 and the plug 2 A tuyere member 10 (which is an embodiment of the tuyere member according to the present invention) will be described as an example. The method of installing the surrounding bricks 1 and the plug 2 on the bottom of the electric furnace 100 is one embodiment of the installation method according to the present invention.

It should be noted that each term used for the purpose of describing the shape of a member in the following description should not be interpreted according to a mathematical definition, and deformations that are normally applied when implementing the shape industrially have been made. should be interpreted to include shape. For example, "quadrilateral" is not limited to a mathematically defined quadrilateral (a shape defined by four straight lines), but rather the transformation normally applied for industrial implementation of a quadrilateral that follows a mathematical definition ( (rounded, chamfered, etc.) that can be regarded as substantially rectangular.

[Configuration of electric furnace]
First, the peripheral brick 1, the tuyere member 10, and the electric furnace 100 to which the installation method is applied according to the present embodiment will be described (Fig. 1). The electric furnace 100 according to the present embodiment has a configuration known as an electric furnace used as a molten metal container. The electric furnace 100 has a substantially cylindrical main body 101 made of a refractory material. A bottom portion 100 a of the electric furnace 100 is formed in a curved shape with a central portion protruding outward (downward), and a main body portion 101 forms a curved bottom surface 102 .

An iron shell (not shown) covering the main body 101 is provided on the bottom 100 a of the electric furnace 100 . The tuyeres 103 provided on the bottom portion 100 a are connected to a refining gas supply source (not shown), and are configured to blow refining gas into the electric furnace 100 through the tuyeres 103 . Note that the heating means and the like provided in the electric furnace 100 are of a known configuration, and illustration and description thereof are omitted.

[Configuration of tuyere member]
Tuyere member 10 comprises a plurality of surrounding bricks 1 and a plug 2 . A plurality of perimeter bricks 1 are arranged surrounding the plug 2 (FIGS. 2, 3). 2 and 3 also show the hearth bricks R installed further outside the surrounding bricks 1, but the hearth bricks R are not a component of the tuyere member 10. As shown in FIG.

The plug 2 has a core portion 21 including a refractory and capillaries 21 a embedded in the refractory, and a block portion 22 provided surrounding the core portion 21 . The core portion 21 further includes a gas pool 21b and an air charge line 21c (Fig. 3).

The narrow tube 21a, the gas pool 21b, and the air supply pipe 21c are members that form a flow path for refining gas supplied from a refining gas supply source (not shown). The fine tube 21a is a straight tube made of stainless steel and having a hole diameter of 2 mm. In the present embodiment, six capillaries 21a are opened on a core body top surface 21d of the core body portion 21, which is a surface exposed to the inside of the electric furnace 100 (bottom surface 102). Here, the core body top surface 21d is a part of the plug top surface 2a, which is the surface of the plug 2 exposed to the inside (bottom surface 102) of the electric furnace 100 and arranged. Two of the six capillaries 21a appear in the cross section of FIG. The gas pool 21b is a box-shaped member that is in fluid communication with all of the six capillaries 21a on the proximal end side of the plug 2, and the refining gas supplied from the refining gas supply source through the air supply pipe 21c is supplied to each capillaries 21a. play a distributive role.

Block portion 22 is made of refractory material. Although the refractory is not particularly limited, for example, a known magnesia-carbon refractory can be used. The composition of the refractory is also not particularly limited, but may be, for example, a magnesia-carbon refractory containing 70% to 95% by weight of magnesia and 5% to 30% of carbon. The composition of the refractory material forming the refractory portion of the core portion 21 and the composition of the refractory material forming the block portion 22 may be the same or different.

In the plug 2 according to this embodiment, the truncated cone-shaped core portion 21 is surrounded by the block portion 22, and the plug 2 as a whole is configured in the shape of a truncated quadrangular pyramid. Therefore, the cross section of the plug 2 is square. However, the shape of the plug 2 is appropriately selected as a shape corresponding to the shape of the bottom of the electric furnace 100 in which the plug 2 is installed.

Like the plug 2, the surrounding brick 1 according to the present embodiment is configured in the shape of a truncated quadrangular pyramid. However, the quadrangular cross section of the surrounding brick 1 is a rectangle. Hereinafter, the direction along the long sides of the rectangle will be referred to as the longitudinal direction, and the direction along the short sides will be referred to as the lateral direction.

Surrounding bricks 1 are made of refractory material. Although the refractory is not particularly limited, for example, a known magnesia-carbon refractory can be used. The composition of the refractory is also not particularly limited, but may be, for example, a magnesia-carbon refractory containing 70% to 95% by weight of magnesia and 5% to 30% of carbon. The composition of the refractory material forming the surrounding brick 1 and the composition of the refractory material forming the plug 2 may be the same or different.

The longitudinal length L1 of the perimeter brick 1 is substantially the same as the longitudinal length L2 of the block portion 22 of the plug 2 . Here, the longitudinal direction of the surrounding brick 1 and the block portion 22 is the vertical direction in the paper surface of FIG. is the direction. In addition, "substantially the same" means that the longitudinal lengths of the surrounding brick 1 and the block portion 22 are close enough to be regarded as the same by those skilled in the art. It does not require that the two be exactly the same. More specifically, for example, a 2% error can be allowed for the length L2 of the block portion 22 in the longitudinal direction, but the invention is not limited to this.

Normally, when providing this kind of tuyere in the bottom of an electric furnace (FIG. 4), it is customary to surround the plug 2 with a surrounding brick 3 that is shorter than the block portion 22 of the plug 2 . In this case, the length of the surrounding bricks 3 is insufficient, so it is necessary to raise the bottom. However, if the surrounding bricks 3 surrounding the block portion 22 of the plug 2 are shorter than the block portion 22, when the refractory material (not shown) further surrounding the surrounding bricks 3 thermally expands, the lower surface of the surrounding bricks 3 will become the plug. 2, which could cause the plug 2 to break. In the tuyere member 10 according to this embodiment, the length L1 in the longitudinal direction of the surrounding brick 1 and the length L2 in the longitudinal direction of the block portion 22 of the plug 2 are substantially the same. Even if the surrounding refractory material expands, the stress associated with the expansion is less likely to be applied to the side surface of the plug 2 . Therefore, damage to the plug 2 can be prevented, and a longer service life of the plug 2 can be expected.

Further, when discharging molten metal from this type of electric furnace, the entire electric furnace is tilted and the molten metal is sometimes poured out from an upper opening (not shown) of the electric furnace. When such an operation is performed, since gravity acts in the lateral direction of the tuyere, the force between the members constituting the tuyere (the surrounding brick 1 and the plug 2 in this embodiment) and the tuyere and the bottom brick R may open. When the joint opens, molten metal enters the joint, causing damage to the refractory material forming the tuyere. In this embodiment, since the length L1 in the longitudinal direction of the surrounding brick 1 and the length L2 in the longitudinal direction of the block portion 22 of the plug 2 are substantially the same, the electric furnace 100 tilts and the tuyere member 10 Even if gravity acts in the transverse direction (horizontal direction of the paper surface of FIGS. 1 and 3), the surrounding brick 1 and the plug 2 move easily together, thereby making it difficult for the joint to open. Therefore, the plug 2 can be expected to have a longer life.

The area of the top surface 1a of the surrounding brick 1, which is the surface exposed to the inside (bottom surface 102) of the electric furnace 100, is preferably 40% or more and 70% or less of the area of the plug top surface 2a. When the area of the top surface 1a is 40% or more of the area of the plug top surface 2a, it is possible to more effectively suppress the stress accompanying the expansion of the refractory around the surrounding brick 1 from being transmitted to the plug 2. Further, if the area of the top surface 1a is 70% or less of the area of the top surface 2a of the plug, the dimensions of the surrounding bricks 1 can be set to a scale that facilitates construction, and construction can be performed with high accuracy. More preferably, the area of the top surface 1a is 45% or more of the area of the plug top surface 2a. Further, the area of the top surface 1a is more preferably 65% or less of the area of the plug top surface 2a.

Further, the width T1 of the top surface 1a in the short direction (an example of the average width of the top surface in the short direction) corresponds to the width T2 of the top surface 2a of the plug (plug top surface) along the direction extending in the short direction. It is preferably 20% or more and 50% or less of the average width of the surface. Here, the lateral direction of the top surface 1a is considered for each of the plurality of surrounding bricks 1, and therefore the "direction extending the lateral direction" of the plug top surface 2a to be compared is also considered for the plurality of surrounding bricks 1. each considered. For example, the width T2A of the plug top surface 2a to be compared with the width T1A of the top surface 1a of the surrounding brick 1A in FIG. On the other hand, the width T2B of the plug top surface 2a to be compared with the width T1B of the top surface 1a of the surrounding brick 1B in FIG. 2 is the width along the vertical direction of the page of FIG.

When the width T1 of the top surface 1a is 20% or more of the width T2 of the plug top surface 2a, it is possible to more effectively suppress the transmission of the stress caused by the expansion of the refractory around the surrounding brick 1 to the plug 2. . In addition, the width W of the surrounding brick 1 in the longitudinal direction tends to be a value of a level that is easy to handle. More preferably, the width T1 of the top surface 1a is 25% or more of the width T2 of the plug top surface 2a.

[Method of installing a tuyere at the bottom of a molten metal refining vessel]
Next, an installation method according to this embodiment will be described. The installation method according to the present embodiment includes a step of installing a plug 2 (hereinafter referred to as a plug installing step) and a step of installing a plurality of surrounding bricks 1 (hereinafter referred to as a surrounding brick installing step). Note that the tuyere member 10 is completed when both steps are completed. That is, at the completion of both steps, a plurality of surrounding bricks 1 will be arranged surrounding the plug 2 .

Here, the order of the plug installation process and the surrounding brick installation process is not limited, but it is common to carry out the plug installation process first. When the plug installation process is carried out first, a plurality of surrounding bricks 1 are arranged around the previously installed plug 2 so that no gap is formed, and the plug 2 is surrounded by the plurality of surrounding bricks 1. Realize a state where If the plug installation process is carried out first, it is easy to install the surrounding bricks 1 around the plug 2 without gaps.

However, it does not prevent the surrounding brick installation step from being carried out first. When the step of installing the surrounding bricks is performed first, an open area is provided in consideration of the size of the plug 2, and after arranging a plurality of surrounding bricks 1, the plug 2 is inserted into the open area. Moreover, after installing a part of the surrounding bricks 1, the plug 2 may be installed, and the rest of the surrounding bricks 1 may be installed to complete the enclosing of the plug 2. In this case, the surrounding brick installation process, the plug installation process, and the surrounding brick installation process are performed in this order.

[Other embodiments]
Finally, other embodiments of the present invention surrounding bricks, tuyere members and methods of installing tuyeres in the bottom of a molten metal refining vessel are described. It should be noted that the configurations disclosed in the respective embodiments below can also be applied in combination with configurations disclosed in other embodiments unless there is a contradiction.

In the above-described embodiment, the configuration in which the cross section of the surrounding bricks 1 is rectangular has been described as an example. However, the cross-sectional shape of the surrounding bricks according to the present invention is not particularly limited, and may be trapezoidal, for example.

In the above-described embodiment, the configuration in which the cross section of the plug 2 is rectangular has been described as an example. However, the cross-sectional shape of the plug according to the present invention is not particularly limited, and may be trapezoidal, for example.

Depending on the cross-sectional shape of the surrounding brick, the width of the top surface in the short direction may vary depending on the measurement position. Similarly, depending on the cross-sectional shape of the plug, the width of the top surface of the plug in the lateral direction may vary depending on the measurement position. In such a case, the average width of the top surface in the transverse direction is preferably 20% or more and 50% or less of the average width of the plug top surface along the direction extending in the transverse direction. Here, the "average width" is the average value of widths at all positions where widths can be measured. For example, if the top surface of the surrounding bricks is trapezoidal and the distance between the upper and lower bases (the "height" of the trapezoid) is longer than the length of the upper and lower bases, the upper The average value of the length of the bottom and the length of the bottom is the average width of the top surface in the transverse direction.

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are examples in all respects, and that the scope of the present invention is not limited by them. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the scope of the present invention. Therefore, other embodiments modified without departing from the gist of the present invention are naturally included in the scope of the present invention.

The invention is further illustrated by the following examples. However, the following examples do not limit the present invention.

〔Test method〕
Surrounding bricks 1 and plugs 2 were installed in the arrangement shown in FIGS. The dimensions of the surrounding bricks 1 for each of the examples and comparative examples are as shown in the table below. In each example, the plug 2 had a square plug top surface 2a with a side of 300 mm and a length L2 of the block portion 22 in the longitudinal direction of 1550 mm. Since the plug top surface 2a is a square with one side of 300 mm, the area of the plug top surface 2a is 90000 mm ² . In addition, the undescribed conditions for the surrounding bricks 1 and the plugs 2 conformed to the above embodiment.

〔Evaluation methods〕
(Joint opening)
For each of the examples and comparative examples, the joint opening was evaluated using a clearance gauge. The evaluation results were expressed in four grades from A to D. The criteria for each level are as follows.
A: Less than 0.5 mm B: 0.5 mm or more and less than 1.0 mm C: 1.0 mm or more and less than 3.0 mm D: 3.0 mm or more

(Workability)
For each of the examples and comparative examples, the workability was evaluated based on the weight per surrounding brick. The evaluation results are expressed in four grades from A to D. The criteria for each level are as follows.
A: less than 200 kg per surrounding brick B: 200 kg or more and less than 250 kg per surrounding brick C: 250 kg or more and less than 300 kg per surrounding brick D: 300 kg or more per surrounding brick

〔result〕
Tables 1 to 3 show the joint opening and workability evaluation results for each of the examples and comparative examples. In any of Examples 1 to 11 in which the length L1 of the surrounding brick 1 is 1550 mm (same as the length L2 of the block portion 22), Comparative Examples 1 to 3 in which the length of the surrounding brick 1 and the block portion 22 are different Compared to , the joint opening was suppressed. Therefore, in Examples 1-11, the plug 2 can be expected to have a longer life than Comparative Examples 1-3.

Table 1: Construction of blocks in Examples and evaluation results

Table 2: Construction of blocks in Examples and evaluation results

Table 3: Construction of blocks of comparative examples and evaluation results

INDUSTRIAL APPLICABILITY The present invention can be used, for example, to install a tuyere at the bottom of a molten metal refining vessel.

REFERENCE SIGNS LIST 1: Surrounding brick 1a: Top surface 2: Plug 2a: Plug top surface 21: Core part 21a: Capillary tube 21b: Gas pool 21c: Air supply pipe 21d: Core body top surface 22: Block part 3: Surrounding brick (conventional technology)
DESCRIPTION OF SYMBOLS 10: Tuyere member 100: Electric furnace 100a: Bottom part 101: Body part 102: Bottom surface 103: Tuyere R: Hearth brick

Claims (6)

A tuyere member for use in the bottom of a molten metal refining vessel, comprising:
A plug having a core portion including a refractory and capillaries embedded in the refractory, a block portion provided surrounding the core portion , and a plurality of surroundings disposed surrounding the plug a brick, wherein the longitudinal length of the surrounding brick is substantially the same as the longitudinal length of the block portion of the plug;
The top surface of the surrounding bricks, which is the surface exposed to the inside of the molten metal refining vessel, is substantially rectangular, and the area of the top surface of the surrounding bricks is exposed to the inside of the molten metal refining vessel. A tuyere member that is 40% or more and 70% or less of the area of the plug top surface of the plug, which is the surface that is arranged as a flat surface . A tuyere member for use in the bottom of a molten metal refining vessel, comprising:
A plug having a core portion including a refractory and capillaries embedded in the refractory, a block portion provided surrounding the core portion, and a plurality of surroundings disposed surrounding the plug a brick, wherein the longitudinal length of the surrounding brick is substantially the same as the longitudinal length of the block portion of the plug;
The top surface of the surrounding bricks, which is the surface exposed to the inside of the molten metal refining vessel, is substantially rectangular, and the average width of the top surface of the surrounding bricks in the transverse direction is A tuyere member that is 20% or more and 50% or less of the average width of the plug top surface of the plug along the extending direction . When viewed from the inside of the molten metal refining vessel, the top surface of the plug has a square shape, the length of the long side of the rectangle of the top surface of the surrounding brick is longer than one side of the top surface of the plug, and the circumference The four surrounding bricks surround the plug such that one short side of the rectangular top surface of the brick and one of the four sides of the top surface of the plug are aligned on the same straight line. 3. The tuyere member according to claim 1 or 2, arranged so that no gap is formed between the tuyere member . A method of installing a tuyere at the bottom of a molten metal refining vessel, comprising:
installing a plug having a core portion including a refractory and capillaries embedded in the refractory and a block portion provided surrounding the core portion;
placing a plurality of perimeter bricks surrounding the plug;
the longitudinal length of the perimeter brick used adjacent to the plug is substantially the same as the longitudinal length of the block portion of the plug;
The top surface of the perimeter brick is substantially rectangular,
The top surface of the surrounding bricks, which is the surface exposed to the inside of the molten metal refining vessel, is substantially rectangular, and the area of the top surface of the surrounding bricks is exposed to the inside of the molten metal refining vessel. A method of installing a tuyere at the bottom of a molten metal refining vessel, which is 40% or more and 70% or less of the area of the plug top surface of the plug, which is the surface arranged as a flat surface. A method of installing a tuyere at the bottom of a molten metal refining vessel, comprising:
installing a plug having a core portion including a refractory and capillaries embedded in the refractory and a block portion provided surrounding the core portion;
placing a plurality of perimeter bricks surrounding the plug;
the longitudinal length of the perimeter brick used adjacent to the plug is substantially the same as the longitudinal length of the block portion of the plug;
The top surface of the perimeter brick is substantially rectangular,
The bottom of the molten metal refining vessel, wherein the average width of the top surface of the surrounding brick in the transverse direction is 20% or more and 50% or less of the average width of the top surface of the plug along the direction extending in the transverse direction. How to install tuyeres in . When viewed from the inside of the molten metal refining vessel, the top surface of the plug is square, and the long side of the rectangle of the top surface of the surrounding brick is longer than one side of the top surface of the plug,
In the step of installing a plurality of the surrounding bricks surrounding the plug, when viewed from the inside of the molten metal refining vessel, one short side of the rectangle of the top surface of the surrounding bricks and one of the four sides of the top surface of the plug 5. The step of surrounding the plug with four of the surrounding bricks so that one side of the plug is arranged on the same straight line so that no gap is formed between the surrounding bricks and the plug. 6. A method of installing a tuyere at the bottom of a molten metal refining vessel according to 5 .

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