JPS6360087B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a pigtail receiving port of a pig iron mixer car used for transporting and storing hot metal when charging hot metal from a blast furnace to a steelmaking furnace. It is something. More specifically, the present invention relates to an improvement in the configuration of this pigtail mouth refractory.

[Conventional technology] As is well known, in the case of mixed iron trucks,
It has a tiltable cylindrical furnace body, and an pigtail receiving port is provided in the upper part of this cylindrical furnace body. Then, by tilting the furnace body, the molten pig iron stored inside is discharged by pouring it out from this pigtail receiving port.

FIG. 2 is a schematic diagram of this pigtail receiving port viewed from above.
is enclosed, and a refractory 3 is provided on the inner circumferential surface of this iron skin 2, thereby forming an pigtail receiving port 4.

Conventionally, the pigtail receiving port of a pig iron mixer car was constructed using irregularly shaped bricks, but integral construction using castable bricks is also being carried out for the purpose of shortening the construction time and reducing the cost of refractories and construction costs.

[Problems to be Solved by the Invention] However, when the castable is used to integrally construct the pigtail car receiving hole, cracks occur on the long axis side of the ellipse, and during use, the cracks expand deep and wide (so-called groove-shaped welding). There is a disadvantage that the life of the pigtail hole is determined even though there is sufficient remaining thickness in other parts (due to loss).

That is, as shown in FIG.
has an elliptical shape with a long axis in the width direction of the pig iron mixer car 1, and when the pig iron receiving port 4 is integrally constructed with castable as the refractory 3, the inner surface (operating surface) of the pig iron receiving port 4 is covered with hot metal. It is repeatedly subjected to radiant heat from the hot metal and atmospheric cooling after the hot metal is discharged. Therefore, expansion stress and contraction stress are repeatedly applied to the castable, and cracks 5 occur on the operating surface of the castable. In particular, as shown in FIG. 2, the cracks 5 are largely generated in a portion (hereinafter sometimes referred to as the discharge side) in the long axis direction of the ellipse of the pigtail hole. For this reason, as the pig iron mixer 1 is tilted and the slag and hot metal are discharged repeatedly, the crack 5 that has formed in the pig iron receiving port 4 becomes a groove-like erosion 6 and expands as shown in Fig. 3. Eventually, the pigtail hole was forced to be repaired.

[Means and effects for solving the problems] The present invention provides a slit for forming a crack starting point at a specific part of the inner circumferential surface of the castable refractory in a pigtail hole where the castable refractory is installed. be.

The effects achieved by such a configuration will be described below with reference to the process that led to the invention of the present invention.

The present inventor has proposed the methods shown in Figs. 4 and 5 (cross-sectional view of Fig. 4) as a measure to prevent cracks occurring on the long axis side (discharge side) of the elliptical shape of the castable construction body of the pigtail car receiving pigtail hole. As shown, two precast blocks 7 were arranged symmetrically at the receiving port in the short axis direction of the ellipse, and castable was poured into the back and discharge side of the blocks.

The purpose of this measure is to cause cracks to occur in the boundary 8 caused by the precast block 7 and the castable poured around it, thereby preventing cracks from occurring on the discharge side. be.

According to this measure, cracks on the discharge side when integral construction is carried out are eliminated by cracks occurring at the boundary 8 between the precast block 7 and castable caster 3, which is effective in preventing the occurrence of cracks on the discharge side. Ta.

As a result of this trial, it was possible to generate appropriate cracks in the castable construction body at a predetermined location other than the discharge side of the pigtail hole, which is similar to using a precast block, thereby extending the life of the pigtail hole. We also obtained some promising and useful knowledge.

However, as the precast block 7 becomes thinner due to erosion, as shown in FIG. It was recognized that there was a problem in which the pigtail hole had to be repaired even though it had some life left. (The code 9 is the fallen part,
10 indicates the remaining portion. ) Also, as a method of forming such a crack initiation part,
As shown in Figures 7 and 8, two castable
An attempt was made to construct the project in stages. That is, as shown in FIG. 7, first, the space into which the castable is poured is divided into a discharge side part and other parts by a partition plate 11, and one of them (the discharge side part in FIG. 7) is first divided into a first part. After performing the first application and allowing it to harden, a second application is performed on the other side.

In this method, the pouring layer 14 between the first construction body 12 and the second construction body 13 acts like a joint and becomes the site where cracks occur, so cracks occur on the discharge side of the pigtail hole. It has the effect of suppressing this.

However, since the construction will be carried out in two parts,
It usually takes two days to construct just the pigtail hole, which poses a problem of poor work efficiency. Also, middle frame 15 and iron skin 2
The lower part of the partition plate 11 that is set between the two parts is in contact with the pig iron car ceiling brick 16 (see FIG. 6), which results in a complicated shape and is difficult to fix.There are also problems in that construction errors are likely to occur.

Therefore, the inventor of the present invention believes that in order to prevent the occurrence of cracks on the discharge side of the pigtail receiving hole of a pig iron mixer car, it is extremely effective to take measures to generate cracks in a predetermined part other than the discharge side of the pigtail receiving hole. The effect was investigated using a 1/8 model of the pigtail hole. This method is based on a sample in which a slit forming plate 17 is installed in a truncated elliptical inner frame as shown in FIGS. 9 and 10 (a cross-sectional view of FIG. The occurrence of cracks was investigated for samples constructed without using the slit forming plate 17. Specifically, after heating the inner surface of a sample of the same shape to 1500℃ for 15 minutes,
We investigated the occurrence of cracks in the castable after repeating the heating/cooling cycle of 10 minutes of air cooling.

As a result, in the case of the sample constructed integrally without using the slit forming plate, the inner ellipse long axis surface (discharge side)
A crack of 0.5 mm occurred on both sides, whereas in the sample in which the slit forming plate was set, a crack occurred in the part of the slit forming plate, and a crack of 0.05 mm or less occurred on the long axis side of the inner ellipse. It was found that the occurrence of micro-cracks was suppressed, and that creating slits at the receiving port of the pig iron mixer car was effective in suppressing cracks on the discharge side. In addition, as shown in Fig. 7 and Fig. 8, in the case of the sample which was applied in two steps, there was a gap of 0.05 mm on the discharge side.
Only one microscopic crack as described below occurred, and the result was almost the same as that of the sample using the slit forming plate.

The present invention was completed based on this knowledge.

[Embodiment] FIG. 1 is a plan view showing the configuration of a pigtail hole according to an embodiment of the present invention. Also, Figure 11 shows the XI of Figure 1.
It is a sectional view of XI.

As shown in the figure, the pigtail receiving port 4 of the pig iron mixer car 1 is constructed by constructing castable refractories 3 inside the iron shell 2, and the inner circumferential surface of the castable refractories 3 has slits at four locations. 18 is provided in a shape cut from the inner periphery. Note that this pigtail receiving port 4 has an elliptical shape.

The manner in which the slit 18 is installed will be explained below.

(b) The installation position of the slit 18 is such that the opening angle α formed by the two slits on the inner circumferential surface is 60° with respect to the focal point on the short axis b of the ellipse that is far from the inner circumferential surface of the castable refractory. A position at an angle of ~70° is preferred.

The reason why the angle α is set to 70° or less is as follows. In other words, in order to prevent the occurrence of cracks on the discharge side, it is more effective to set α at a position larger than 70 degrees, but when discharging slag and hot metal, if the slit position is close to the discharge side, slag and The maximum α was set at 70° because there is a high possibility that the area will come in contact with hot metal and suffer groove-like erosion. On the other hand, if α is less than 60°, the length of the operating surface of the caster on the discharge side becomes long, and the effect of expansion and contraction due to repeated heating and cooling in the air becomes large, and the effect of suppressing cracks on the discharge side becomes small.

(b) The slit 18 is preferably formed at an angle as close to perpendicular as possible to the tangential direction θ of the inner circumferential surface, for example, 90°±10°. In most cases, the direction in which the crack grows from the tip of the slit is the direction in which the slit extends, but in reality, a slight angular deviation may occur. Therefore, if the slit is installed at an oblique angle, the direction of crack growth from the slit tip may be closer to the operating surface, which may cause peeling damage. For this reason, it is preferable that the slit 18 be formed at an angle as close to perpendicular to the tangential direction θ of the inner circumferential surface.

(c) The gap between the slits is preferably 5 mm or less. If the hot metal in the pig iron mixing car is cooled in the atmosphere when the car is empty after being discharged, the temperature at the pigtail receiving port will decrease approximately.
The temperature is expected to be around 600℃. The amount of thermal expansion of the castable at 600℃ (however, the amount of thermal expansion in the length of the castable between the slits) is approximately 5 mm.
Therefore, the slit gap is preferably 5 mm or less. If the slit gap is 5 mm or more, the gap remains even when the castable refractory is thermally expanded, which may cause intrusion of hot metal, slag, etc., which is not preferable.

(d) If the slit depth l is less than 30 mm, cracks that grow from the tip of the slit may occur parallel to the operating surface, making it easy to cause peeling damage. In addition, as will be described later, when using a type of board that burns away as a board for forming slits, it is undesirable to insert it deep into the back of the caster because the temperature at the back of the caster is low, so it does not expand and the gap remains open. . Therefore, when using a type of board that burns out, the slit should be 1/2 of the lining thickness.
It is preferable to set it up to.

In addition, when providing slits in the entire thickness of the lining, a plate made of plastic mixed with refractory powder may be used as the plate material for forming the slits. In this case, since the plate material is not completely burned down, it is possible to avoid gaps remaining during use, and reliable cracks are generated. In addition, if a film-like synthetic resin with a high tensile strength of 0.2 mm or less can be set using a special holder, the gap between the slits will be small, and the slits will close even with small thermal expansion, so the total thickness of the lining can be A slit may be formed with a depth of

(e) The horizontal cross-sectional shape of the slit is rectangular, triangular,
Alternatively, a shape in which the short side is semicircular (having a so-called radius) is suitable.

Such a slit can be easily formed by attaching a plate material 20 for forming the slit to the middle frame 19, as shown in FIG. 12, when constructing the castable refractory.

The material of this board 20 is a hard plastic board.
Suitable materials include hard materials that are burnt out or partially burned out, such as plywood boards and plastic forming plates mixed with refractory powder; materials that are not burned out, such as refractories and metals; and synthetic resin films and metal plates that do not stretch easily when using special jigs.

A specific example will be explained below.

Four plastic plates of 50w x 800v x 2t (unit: mm) were set as slit forming plates in the inner frame of the pigtail receiving port of the pig iron mixer so that the angle α in Fig. 1 was 60°. The plastic plate was fixed in a direction perpendicular to the tangent to the curved surface of the middle frame.

The inner frame with the plastic plate attached was set in the receiving port of the pig iron mixer car, and the low cement castable was poured using a rod-shaped vibrator. After the castable had hardened, the inner frame was removed, leaving the plastic plate inside the castable.

The pig iron mixer constructed in this way will not have a short service life due to groove erosion on the discharge side, unlike conventional castable integral construction, and will not have the lower part of the block falling off, as in the case of using a precast block. An excellent effect was obtained in extending the life of the pigtail car receiving port without causing any problems.

Conventionally, the throughput amount was 50,000 to 70,000 tons using integrated construction and 60,000 to 80,000 tons when using precast blocks, but in this example, 70,000 to 90,000 tons were obtained, which is much better than the conventional method.
This is a 1.2 to 1.4 times longer life.

[Effects] As is clear from the above explanation, the present invention reliably prevents the occurrence of cracks in the castable refractory on the discharge side of the pig iron receiving port, and prevents the groove-like melting damage that grows from the cracks that has conventionally occurred. The thickness of the castable lining works effectively and provides a long life.

The present invention eliminates the erosion of the discharge gutter due to integral construction, and provides a long service life.

The lining is integrated all the way to the back, so it won't fall off during use.

In order to reliably generate cracks at the slit positions, a double construction method using a partition plate is effective, but it requires two days of construction and is expensive, but with the present invention, it can be done in one day. Almost the same effect can be obtained.

Similar effects can be obtained not only with an elliptical pigtail hole but also with a circular pigtail hole.

It has excellent characteristics such as

[Brief explanation of the drawing]

Figure 1 is a plan view showing the embodiment, Figures 2 and 3.
The figure is a plan view explaining crack or groove-like erosion.
7, 8, and 9 are plan views for explaining measures against cracks, FIGS. 5, 6, and 10 are sectional views of the same, and FIG. FIG. 12 is a perspective view of the middle frame. 1...Pig mix car, 2...Steel skin, 4...Pigtail socket, 18...Slit.

Claims (1)

[Scope of Claims] 1. At the pigtail receiving port of a pig iron mixer car that has a substantially elliptical shape with its major axis in the width direction of the pig iron mixer car and whose inner circumferential surface is coated with castable refractory material, from the inner circumferential surface of the castable refractory material. , a slit for forming a crack starting point is provided in a shape cut from the inner circumferential surface of the ellipse at a portion between the short axis and the long axis of the ellipse and not in contact with the hot metal discharged when the pig iron mixer is tilted; A mixed pig iron car receiving port featuring the following. 2. The pig iron mixer wheel receiving port according to claim 1, wherein the gap between the slits is 5 mm or less, and the depth of the slit from the inner circumferential surface is 30 mm or more.