JPH0931509A - Blast furnace tapping gutter - Google Patents

Abstract

(57) [Abstract] [Problem] To extend the life of blast furnace tap iron refractory. SOLUTION: The cross section of the blast furnace tapping gutter is formed in a stepwise manner, in which a hot metal flow portion 5 below the slag metal interface 4 at tapping is narrower than the width of the slag metal interface 4 to form a stepwise shape. The gutter inside angle α formed by the side wall surface and the gutter bottom surface is 60 ° ≦ α ≦ 100
And the angle β between the upper surface of the step and the horizontal line is -30 °
≦ β ≦ 10 °.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory life extension of a blast furnace tappipe, and to a shape of a tappipe for extending the life of the gutter refractory.

[0002]

2. Description of the Related Art A refractory material lined in a taphole has a slag vapor phase interface 3 and a slag metal interface 4 which are greatly damaged, as shown in the cross section of FIG. FIG. 8 shows that the residual refractory line 7 on the side wall 2 of the original refractory is worn as shown by the profile 6 at the position of the slag vapor phase interface 3 and as shown by the profile 8 at the position of the slag metal interface 4. There is. It is known that in the flow direction, as shown in FIG. 9, the vicinity of the outlet of the hot metal from the tap hole is greatly damaged. In particular, since the damage near the outlet is large, the life of the gutter refractory is determined at this part, and the elucidation of the mechanism that the part is greatly damaged and the improvement of the refractory are major problems.

Regarding damage to the slag metal interface, it is said that local damage occurs due to Marangoni convection or electrochemically. However, the mechanism of damage in the flow direction, that is, damage that increases near the hot metal outlet is not well understood. In order to prevent gutter damage, refractory materials and gutter shapes have been conventionally improved even though the damage mechanism is unknown. For example, Japanese Patent Application Laid-Open No. 55-134112 discloses a technique of inclining a side wall portion near an interface where hot metal and slag come into contact with each other by 30 to 80 ° from the vertical direction. Although this technique improves the durability to some extent, it has not been able to reduce the magnitude of damage in the vicinity of the above-described molten iron drop opening.

[0004] Generally, although the damage rate cannot be reduced by increasing the thickness of the refractory construction at the portion where the damage is large, the service life has been improved by extending the life.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to reduce the above-mentioned large melting loss near the hot metal outlet and is intended to be reduced by changing the cross-sectional shape of the hot metal gutter. is there.

[0006]

Means for Solving the Problems The inventors of the present invention consider that the above-mentioned large melt loss near the hot metal outlet is due to the flow of the hot metal and the molten slag, and the hot metal in the hot metal gutter and the molten metal The slag flow was analyzed by a water model experiment. The results obtained were as follows. (1) Diffusion of refractory components in the molten slag in the boundary film at the slag metal interface is the rate-determining process of melting loss of the refractory. (2) In addition, the flow velocity is maximum in the laid portion near the hot metal outlet, but the laid portion is not significantly damaged, and an increase in the flow velocity in the portion in contact with the hot metal does not lead to an increase in damage. (3) The hot metal flow flying in the air from the tap hole hits the floor and flows downstream, and is divided into both sides toward the side wall.
After that, the flow crawls along the side wall slightly downstream of the hot metal outlet, and the hot metal boils on the surface. (4) As a result, the flow in this part becomes large, and the damage in this part becomes the largest.

Based on the above results, it was found that it is possible to suppress the melting loss of refractory materials by suppressing the flow velocity near the side wall of the slag metal interface, and completed the present invention. That is, in the present invention, in the blast furnace tap pipe, a step is provided on the side wall below the slag metal interface during tapping, and a narrow portion narrower than the width of the slag metal interface is provided below the circulation portion of the hot metal. It is a blast furnace tap iron gutter characterized by.

In this case, it is preferable that the gutter inside angle α formed by the side wall surface of the narrow portion and the laying horizontal line is 60 ° ≦ α ≦ 100 °, and the upper surface of the step and the horizontal line. The angle β is preferably a positive value when the gutter center side of the step is low, and is preferably −30 ° ≦ β ≦ 10 °.

Here, the slag metal interface refers to a height position corresponding to a steady slag metal interface at the time of normal tapping in the cross section of the hot metal gutter which has not yet been melted.
The floor horizon refers to the horizon when the bottom surface of the cross section of the hot metal gutter is the horizon, and refers to the imaginary horizon at the floor position when it is not the horizon.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in the embodiment of the present invention in FIG. 1, a slag metal interface 4 at the time of tapping of a cross section of a blast furnace tap pipe is shown.
It is important that the lower hot metal circulation portion 5 is narrower than the width of the slag metal interface 4. Such narrowing of the flow path of the hot metal flow section 5 enhances the effect. By doing this 1
The hot metal flow that has climbed up the side wall 2 does not directly wash the side wall portion, and the durability is improved. The flow velocity of hot metal in the bed 1 increases, but the damage in the bed 1 does not become a rate-determining process, so that it is not a problem.

Increasing the refractory construction thickness to the upper side of the slag metal interface 4 as in the prior art shown in FIG. 2 narrows the flow path and increases the damage rate of the slag metal interface. Becomes 3 and 4 are schematic diagrams showing the flow state of the hot metal in the gutter. In the case of the present invention shown in FIG. 3, the hot metal flow crawling up the side wall 2 does not directly wash the side wall portion at the slag metal interface, and the durability is improved. On the other hand, in the conventional gutter shape shown in FIG. 4, since the hot metal flow crawling up the wall directly cleans the side wall portion, the damage becomes large.

The width a of the narrow passage portion in the hot metal flow portion 5 shown in FIG.
And the depth b is preferably as follows, where W is the width of the gutter and d is the depth of the slag metal interface during tapping. The width a is preferably smaller than 0.9 W and larger than 0.33 W. If it is larger than 0.9 W, the durability cannot be improved. If it is less than 0.33 W, the flow velocity in the hot metal becomes too fast, which causes a problem in the corrosion resistance of the bed. Preferably 0.
It is in the range of 35 W or more and 0.5 W or less.

The depth b is greater than 0.33d and is 0.9d
Desirably smaller. If it is smaller than 0.33d, the durability cannot be improved. If it is larger than 0.9d, the molten pig iron side wall portion enters the slag metal interface due to the position change of the molten pig iron height, and rather the damage rate is increased. The range is preferably 0.5d or more and 0.8d or less. Further, when the gutter inner angle formed by the side wall surface of the narrow portion of the hot metal flow portion 5 and the horizontal line of the floor portion is α, it is more effective to satisfy 60 ° ≦ α ≦ 100 °. When the angle is larger than 100 °, the hot metal flow crawls up the side wall, and the flow directly hits the slag metal interface of the side wall portion, which is not desirable. If it is less than 60 °, the refractory is heated on two sides and damage due to thermal shock increases, which is not a good idea. More preferably, 70 ° ≦ α ≦ 95 °.

Further, the angle between the upper surface of the step and the horizontal line is β
Then, it is more effective to set -30 ° ≤ β ≤ 10 °. Here, β is a positive value when the gutter center side of the stage is low, and a negative value when it is high. If β is larger than 10 °, the split flow of the hot metal flow that has climbed up the side wall directly collides with the slag metal interface of the side wall part from the upper surface of the narrow part, which is not desirable. β
Is less than -30 °, the refractory is heated on two sides and damage due to thermal shock increases, which is not a good idea. More preferably, it is −20 ° ≦ β ≦ 5 °.

On the other hand, the angle formed by the upper surface of the step and the side wall surface is defined by γ
Then, it is desirable that the angles α and β satisfy γ ≧ 60 ° while satisfying the above conditions. This is because if γ is smaller than 60 °, the refractory will be heated on two sides and damage due to thermal shock will increase. More preferably, γ ≧ 70 °.

[0016]

[Examples] In a blast furnace tappipe, a core having the inner surface of the gutter shown in FIG. 1 was formed, and a refractory for the gutter was poured into the core. In FIG. 1, the gutter width W = 800 mm, the narrow width hot metal passage width a = 5
The depth was 60 mm, the slag metal interface depth was 400 mm, and the height of the hot metal passage in the narrow portion was 300 mm. After normal drying,
I actually used it. Compared to before improvement, the damage rate near the hot metal outlet decreased, but there was almost no change on the upstream side or downstream side. Also in this case, the maximum damage site was in the vicinity of the hot metal outlet. The damage rate at the maximum erosion site was determined. Passing capacity is 34,800 tons and 75,200 tons
At the time of n, the residual pig iron is removed and the damage rate per 1,000 tons is usually measured.
Damage rate was calculated in (t). The damage rate is
It became 2.3, 2.5, 2.6 mm / 1,000 tons.

In the blast furnace tappipe, a gutter-shaped core shown in FIG. 5 was formed, and a gutter refractory was poured and constructed. In FIG. 5, the dimensions a and b are the same as those in FIG. 1, and the angle β between the step upper surface and the horizontal is β = 5 °. After normal drying, it was actually used. The basic form of damage was the same as in FIG. The damage rate at the maximum erosion site was determined. When the amount of pig iron is 35500 tons and 75000 tons, the residual pig iron is removed and the damage rate is measured.
The damage rate was calculated to be 00 tons. The damage rates were 1.8, 1.9 and 2.1 mm / thousand tons, respectively.

FIG. 6 shows an example in which β = 10 ° and α = 80 °, and FIG. 7 shows an example in which β = −20 ° and α = 100 °. FIG. 10 is a graph showing a damage rate per 1,000 tons of the amount of hot metal in the gutter when the gutter inner angle α formed by the narrow portion side wall and the laying horizontal line is changed in the cross section of the hot metal gutter shown in FIG.
Good results are shown at α = 60 to 100 °.

FIG. 11 is a graph showing the rate of damage per thousand tons of hot metal in the gutter when the angle β between the upper surface of the step and the horizontal line is changed in the cross section of the hot metal gutter shown in FIG. Good results are shown at β = −30 to + 10 °. As described above, it is clear that the present invention reduces the damage rate and improves the mode life, and it is understood that the tapping gutter of the present invention is excellent.

[0020]

According to the present invention, it is possible to extend the service life of the tap-iron gutter refractory. Further, by extending the life of the refractory, the refractory basic unit can be reduced, and at the same time, the frequency of refractory construction can be reduced, which can contribute to the reduction of so-called heavy muscle labor.

[Brief description of drawings]

FIG. 1 is a sectional view showing a blast furnace tap pipe according to the present invention.

FIG. 2 is a sectional view of a conventional gutter.

FIG. 3 is an explanatory view showing a gutter damage suppressing mechanism of the embodiment.

FIG. 4 is an explanatory view of a conventional gutter-shaped damage mechanism.

FIG. 5 is a cross-sectional view showing an example in which angles α and β are changed.

FIG. 6 is a cross-sectional view showing an example in which the angles α and β are changed.

FIG. 7 is a cross-sectional view showing an example in which angles α and β are changed.

FIG. 8 is a cross-sectional view showing a typical form of gutter damage.

FIG. 9 is a graph showing the distance from the taphole and the maximum damage depth.

FIG. 10 is a graph showing the damage rate when the angle α is changed.

FIG. 11 is a graph showing a damage rate when the angle β is changed.

[Explanation of symbols]

1 floor 2 side wall 3 slag gas phase interface 4 slag metal interface 5 distribution part 6 profile 7 residual refractory line 8 profile

Claims (3)

[Claims] 1. In a blast furnace tap pipe, a step is provided on a side wall below a slag metal interface at tapping, and a narrow portion narrower than a width of the slag metal interface is provided below a circulation portion of the hot metal. Characteristic blast furnace tap iron gutter. 2. The blast furnace tap pipe according to claim 1, wherein an inner angle α of the gutter formed by the side wall surface of the narrow portion and the horizontal surface is set to 60 ° ≦ α ≦ 100 °. 3. The angle β between the upper surface of the step and the horizontal line
2. The blast furnace tappipe according to claim 1, wherein -30 ° ≦ β ≦ 10 ° is set as a positive value when the gutter center side of the stage is low.