JP2002155307A - Brick for iron tapping hole in blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brick for iron tapping hole in blast furnace with which remaining iron and slag in furnace can be reduced without bringing about a rise in molten iron cost only by only simply elaborating an existing brick for iron tapping hole. SOLUTION: The brick for iron tapping hole in the blast furnace is provided with a through-hole for taking out the molten iron and slag retained in the blast furnace to outside the furnace and composed of a refractory brick laying structural body having a projecting part to the inside of the furnace from a furnace wall surface on a furnace hearth. The upper surface of the projecting part has a gradient of <=45 deg. inclining angle to the horizontal plane toward the furnace wall side from a furnace core side, and the vertical length from the through-hole center of the projecting part on the side surface in the furnace to the side end part at the furnace core on the upper surface of the projecting part is <=1 m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a taphole brick of a blast furnace, and more particularly, to a structure of a taphole brick effective for reducing the amount of residual iron slag in a blast furnace and maintaining a stable operation.

[0002]

2. Description of the Related Art The hearth of a blast furnace is filled with coke, and the voids are filled with slag (also called slag) and hot metal. Since the specific gravity of the coke is lighter than that of the hot metal, as shown in JP-A-4-45213, the coke packed layer 5 floats at the peripheral end of the furnace bottom and only the hot metal exists. It is said that there is an area (hereinafter, referred to as a free space) (see FIG. 2).

The slag accumulated in the hearth during operation is discharged out of the furnace together with the molten iron through a furnace wall through hole, which is called a taphole, at the time of tapping. In FIG. 5, the liquid level 3 of the slag tends to form a gentle slope toward the taphole 1 as shown in FIG.
If tapping is continued, gas will eventually be blown from tap hole 1 instead of slag or hot metal.
Close. As a result, it is often not possible to discharge all the slag accumulated in the furnace outside the furnace during tapping.

In the operation of a blast furnace, the amount of slag remaining in the furnace (hereinafter referred to as the amount of residue) increases, and the liquid level 3 of the slag sometimes reaches the installation position (level) of the tuyere 7. However, in this case, a problem of so-called "tuyere slag return" in which slag flows backward from the tuyere 7 toward the blower tube occurs. As a result, not only can air blowing become impossible or the operation becomes unstable due to malfunction, but also
This causes a serious operation trouble such as cooling of the hearth disclosed in Japanese Patent No. 70813.

[0005] Therefore, researches on means for properly adjusting the so-called "residual iron slag" remaining in the hearth 6 of the blast furnace have been conducted. For example, it is considered that the lower the viscosity of the slag and the larger the particle size of the coke, the more easily the slag passes through the coke packed bed 5, so that the amount of slag remaining in the furnace at the time of tapping is reduced. Therefore, by adding auxiliary raw materials to adjust the slag composition, in the blast furnace operation, raise the fuel ratio and blast temperature to raise the temperature of the slag,
Techniques have been developed to reduce the viscosity of slag.

However, these techniques all require the addition of a new substance or calorific value, and thus increase the cost of the hot metal to be smelted.

Therefore, a technique of increasing the particle size of the coke forming the coke packed layer 5 of the hearth 6 has received more attention. For example, JP-A-5-70813 discloses that
A lance for gas injection is inserted into the core coke layer of the blast furnace (a portion below the shaft portion where only the course filling layer 5 exists), and the coke forming the core coke layer 5 is directly burned. Proposes a technique in which coke having a small particle diameter in the core coke layer 5 is replaced with coke having a large particle diameter supplied from above. In addition, Japanese Patent Publication No. 6-37649
The gazette intends to form the core coke layer 5 and uses a high-quality coke charged from the furnace top to the center to reduce the particle size of the coke forming the core coke layer 5. We are proposing techniques to make it bigger.

[0008]

However, in the technique of direct combustion of core coke using a lance described in JP-A-5-70813, it is necessary to insert the lance into a high-temperature core coke layer. However, such long-term continuous use of the lance is physically and economically unreasonable and difficult to use. Further, according to the technique described in Japanese Patent Publication No. Hei 6-37649, not only a separate facility for charging the furnace center is required, but also high-quality coke must be produced. Therefore, this technique also causes an increase in hot metal cost and is not preferable.

In view of such circumstances, the present invention provides a tapping method for a blast furnace capable of reducing the amount of residual iron slag in the furnace by simply devising existing taphole bricks without increasing the cost of hot metal. It is intended to provide mouth bricks.

[0010]

Means for Solving the Problems In order to achieve the above object, the inventor has made intensive studies on the structure of taphole bricks for smoothly discharging slag and hot metal stagnating in a furnace, and has made the results of the present invention into the present invention. Embodied.

[0011] That is, the present invention relates to a refractory brick structure having a through hole for extracting hot metal and slag staying in a blast furnace to the outside of the furnace, and having a projecting portion on the hearth from the furnace wall surface to the inside of the furnace. A taphole brick of a blast furnace, wherein the upper surface of the protrusion has a slope of 45 degrees or less with respect to the horizontal from the core to the furnace wall, and the inner surface of the furnace of the protrusion is A taphole brick for a blast furnace, wherein a vertical length from a center of the through hole to an end of the upper surface of the protruding portion on a furnace core side is 1 m or less.

According to the present invention, a taphole is provided forward of the furnace inside.
An area where a large core coke layer does not exist can always be maintained, and the flow of slag and hot metal toward the tap hole becomes smooth. As a result, the amount of residual iron slag in the furnace can be reduced,
Stable operation of the blast furnace is achieved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a taphole brick of a blast furnace, which is an object of the present invention, will be outlined. FIG. 1B is a cross-sectional view showing the vicinity of the taphole on the hearth. Since the taphole 1 is a passage through which hot molten iron or slag is discharged at a speed of several m / sec during tapping, the refractory forming the taphole is easily damaged. Therefore, by extending the taphole brick 18 to the inside of the furnace than the normal furnace wall brick and increasing the taphole depth, it is possible to avoid furnace body damage due to wear of the taphole brick portion. I have. Further, the tap hole is closed by periodically pushing the mud material 17, and the worn tap hole is repaired.

The taphole brick is formed by stacking refractory bricks from the furnace bottom to the vicinity of the taphole.
Since the molten iron slag exceeding 500 ° C stays and flows out, if it protrudes extremely inward from the cylindrical furnace wall brick that constitutes the entire furnace bottom, corners may be lost due to thermal effects. . Therefore, the projecting portion is formed so as to be smoothly connected to the furnace wall brick.

For this reason, as shown conceptually in FIG. 1B, the upper part of the protrusion of the taphole brick is provided with an elevation angle (indicated by the symbol α in the figure) from the inside of the furnace toward the outside of the furnace. It is formed to be inclined. In this case, the taphole brick is usually formed by stacking rectangular bricks, so that the taphole brick upper surface is not necessarily inclined linearly. It is usually formed in steps.

Next, an embodiment of the present invention will be described with reference to the circumstances leading to the invention.

The inventor manufactured a half-cylindrical model hearth 8 as shown in FIG. 3 in order to clarify the factors that determine the amount of residue on the hearth. This model is 1/25 scale of a blast furnace having a hearth diameter of 10 m, and the front surface is formed of a transparent acrylic resin plate so that the inside corresponding to the hearth can be observed. Into this model hearth, plastic beads having a diameter of 6 mm were charged as pseudo coke, and a bead-filled layer 9 was formed. The lower portion of the bead filling layer 9 is supported by a wire mesh to stabilize the shape of the filling layer, and the filling layer itself can be moved up and down. The reason is that, in an actual blast furnace, the specific gravity of coke is much smaller than that of hot metal, so as described above, the coke packed layer floats on the hot metal at the peripheral end of the hearth, and there is no coke packed layer. This is because it is said that there is an area (hereinafter, referred to as free space).

In the model experiment, the specific gravity was 1.8 as the pseudo hot metal.
Of liquid freon 11 and oil 12 having a specific gravity of 0.8 as pseudo slag, and supplying them into the model from the top of the model,
These liquids were discharged through pseudo tap holes 13 provided on the left and right walls alternately. 30 kPa of air 14 was introduced into the model during the liquid supply while imitating the furnace gas. The timing of switching the opening and closing of the pseudo tap hole 13 was based on gas blowing as in the actual blast furnace.

That is, the liquid Freon 11 and the oil 12 are discharged from the pseudo tap hole 13, and when the upper surface 21 of the oil 12 drops to the level of the pseudo tap hole 13, the air 1
Since the hole 4 was discharged from the dummy tap hole 13, the opening and closing of the dummy tap hole 13 were switched at the timing when this phenomenon occurred.

FIGS. 4A and 4B show examples of the experimental results. This is because, as shown in FIG. 4B, when the bead-packed layer in the hearth is gradually lifted and the upper end position of the free space, that is, the boundary position between the bead-packed layer and the furnace wall is variously changed, It is a result of an investigation on the amount of residue (slag) in the hearth. The change of the boundary position was performed by setting the center line position 13a of the pseudo taphole to 0 and moving the entire bead-packed layer up and down. The residue ratio is 0 when no pseudo slag is accumulated above the taphole level.
%, And the value when pseudo slag has accumulated up to 40 mm above the pseudo taphole 13 was determined as 100%. 4A, when the upper end position of the free space 10 is low (H = −
40 mm), the residue amount is large, but the lower end of the furnace wall of the bead-packed layer 9 is lifted up above the simulated tap hole 13 and free
When the upper end of the space is raised (H = + 20, + 4
0, +80 mm), a new finding that the amount of residue is reduced was obtained.

When the beads filling layer 9 is present inside the furnace of the simulated tap hole 13 (see FIG. 5A), gas is blown out before the slag is sufficiently discharged. It was necessary to switch the left and right of the pseudo tap hole. this is,
This is because the resistance of the bead filling layer 9 was large, and the pseudo slag (arrow C) did not easily flow through the inside. On the other hand, when the free space 10 exists inside the furnace of the pseudo tap hole 13 (see FIG. 5B), a phenomenon in which the pseudo slag in the furnace is significantly reduced was confirmed. This means that an annular flow (arrow D) of pseudo slag selectively flowing through the free space 10 inside the furnace of the pseudo taphole 13 is generated, and the pseudo slag is radially (arrow E) from inside the bead packed layer 9. This is because it flows to the return flow D. That is, in the bead-filled layer 9, the pseudo slag flow path is dispersed and the linear velocity decreases, so that it is considered that the resistance decreases and the pseudo slag flows more easily.

Next, the inventor conducted an experiment to clarify the size (size) of the free space 10 for improving the waste property. First, as shown in FIG.
One of the simulated tapholes 13A and 13B is completely covered with the bead filling layer 9, and the degree of the covering is represented by an angle θ from the center of the model. Then, the amount of the residue was measured with the angle θ changed variously, and the result is shown in FIG. FIG. 7 reveals that the pseudo taphole 13A having a free space inside the furnace always has less residue than the pseudo taphole 13B covered with the bead filling layer. On the other hand, in the pseudo tap hole 13B, the waste is deteriorated while the size of the bead-filled layer covering the same is still small, that is, by θ = 10 °. In addition, the pseudo taphole 13A having the free space 10 in front of the taphole furnace has a small free space 10 (θ is 170 ° or more).
Then, the amount of residue rapidly increases. From the above results, when a region without a bead packed layer is formed in front of the pseudo tap hole 13A inside the furnace, the free space 10 is formed at another location (near the furnace wall where no tap hole is installed). It was found that it was more effective to reduce the amount of residue than to make it.

FIG. 8 shows the relationship between the filling state of the beads before the simulated taphole and the shape of the upper surface of each of the oil and liquid chlorofluorocarbon in the experimental apparatus. This shape is the shape at the timing when the air is mixed and discharged from the discharge of oil and liquid Freon from the pseudo taphole.

Since the pseudo slag has a high viscosity, when passing through the bead filling layer 9, the shape of the upper surface 21 is inclined toward the pseudo tap hole 13 (see FIG. 8A). . Since this inclination becomes larger as approaching the pseudo taphole 13, even if only a small area around the taphole 13 is covered with the bead filling layer 9, the cross-sectional shape of the pseudo slag is entirely filled with beads. This is almost the same as the above case covered with the layer 9 (see FIG. 8B). On the other hand, θ = 0
Under the condition of °, that is, when there is the free space 10, since no inclination is formed on the slag surface, almost all the pseudo slag is discharged (see FIG. 8C). According to the above experimental results, the free space 10 does not necessarily need to be present in the entire front of the inside of the taphole furnace. It was confirmed that the residue could be stabilized at a low level.

To summarize the results of these experiments, in order to reduce the amount of residual iron slag in the blast furnace, the free space 10 does not necessarily need to exist at the entire height of the tap hole in the furnace. It turns out that it is only necessary to be in a limited area in front of the pigtail.

The free coke formed on the blast furnace hearth
The space is a result of the balance between the dead weight of the core coke layer and the weight of the upper sediment applied from above the buoyancy applied from the molten iron slag. Deposits such as raw materials and coke in the furnace are very heavy, but a part of the deposits on the upper part of the core coke layer may spread out due to friction with the furnace body and the formation of flare on the furnace body. Due to the shape support, the load on the core coke layer will be significantly reduced and the buoyancy will be greater in the balance. Therefore, the lower end of the core coke layer in the hearth floats above the furnace bottom, and a free space for coke is formed below the bottom.

On the other hand, above the tap hole, the coke is burned and lost by the oxygen blown from the tuyere. At this time, a space called a raceway is formed inside the furnace in front of the tuyere due to the dynamic pressure of the blown air. In the raceway, the coke is swirled by the force of the blowing air and burns. At this time, coke is supplied from the coke packed bed surrounding the raceway into the raceway. Since coke is also supplied from below the raceway, a flow in the ascending direction of coke from the hearth to the tuyere raceway occurs at the hearth side wall. For this reason, the shape of the lower end of the furnace core coke layer has a downwardly convex shape that is lower toward the furnace core and higher at the furnace wall.

Normally, when the coke is piled up in a mountain shape, the angle of the slope is stabilized at a repose angle of about 40 degrees, but the core coke rises toward the raceway in the above furnace. In this case, the direction is upside down, but the inclination angle of the lower end face of the furnace core coke layer is also considered to be stable to about 40 degrees, which is the repose angle. Therefore, the upper end of the free space rises in the vicinity of the furnace wall at an inclination of about 40 degrees from the core to the furnace wall.

For this reason, as shown in FIG. 1 (b), the inclination α of the upper part of the protruding portion of the taphole brick toward the inside of the furnace is formed at an angle larger than about 40 degrees which is the repose angle of coke. In this case, the coke and the taphole brick can be stable in contact with each other. On the other hand, as shown in FIG. 1A, when the inclination α is an angle equal to or smaller than the coke angle of repose, when the coke becomes stable at the angle of repose, the coke does not come into contact with the taphole brick. Coke free
Space will be created. That is, if the slope of the upper part of the tapping brick is formed at an elevation angle equal to or less than the angle of repose of coke from the core to the furnace wall, at least above the tapping brick, the free space of coke Can be formed in advance. The angle of repose of coke fluctuates depending on the particle size distribution and the like.
Do not exceed the degree. Therefore, the upper slope of the protrusion of the taphole brick may be formed at an elevation angle of 45 degrees or less from the furnace core toward the furnace wall.

On the other hand, if the vertical length between the center of the through hole on the inner side surface of the furnace of the protrusion of the taphole brick and the end of the upper surface of the protrusion on the core side is long as shown in FIG. The lower end of the core coke layer in front of the taphole furnace is likely to be in contact with the core side end of the upper surface of the protrusion of the taphole brick. In this state, for example, as shown in FIG. 1 (b), even if a free space for coke is formed in front of the inner surface of the taphole furnace, free space is generated by contact between the taphole brick and the core coke layer above the space.・ Space is interrupted. As a result, even if the core coke layer moves up and down to some extent, it is difficult to increase the free space in front of the tap hole, and as a result, it is difficult to maintain a stable tapping slag.

On the other hand, the vertical length between the center of the through hole on the inner surface of the furnace of the protrusion of the taphole brick and the end of the upper surface of the protrusion on the core side is short as shown in FIG. 1 (a). This increases the chances of breaking the contact between the lower end of the core coke layer and the upper end of the taphole brick protruding portion due to the vertical movement of the core coke layer. If this contact is interrupted, the free space of coke constantly formed above the taphole brick and the free space before the taphole will merge, and as a result, the free space before the taphole will be merged. The space can be enlarged, and the tapping slag becomes good, leading to a stable operation.

As described above, the vertical length between the center of the through hole on the inner surface of the furnace and the end portion of the upper surface of the protruding portion of the taphole brick that can improve tapping residue is determined. for,
FIG. 9 (a) shows a plot of this value in the existing blast furnace and the average value of the slag index for three years from the time of burning in the blast furnace. The vertical height h from the through hole to the upper end shown here is h shown in a schematic vertical cross-sectional view of the tap hole in FIG. It shows the vertical distance between the top of the protruding part of the brick and the top, and each plot is a design value at the time of blast furnace construction. The numerical values in parentheses attached to the plots in FIG. 9 (a) are elevation angles from the horizontal direction from the furnace core to the furnace wall with the upper slope of the taphole brick protrusion at each taphole. It is shown by. In this figure, the slag index is a ratio in which the time from opening to closing in one tapping slag is the denominator and the time during which the slag is flowing out is the numerator.
Each plot in (a) shows the average value of the slag index for three years from the burning of the existing blast furnace. Here, each blast furnace has 2 to 4 tapholes, but since the shape of the taphole bricks is the same for each blast furnace, the average value is obtained all together. A large slag index means that the level of molten slag staying in the vicinity of the tap hole where tapping is performed is low or that the slag easily flows in front of the tap hole. It can be evaluated that the slag is stable.

As can be seen from FIG. 9 (a), the smaller the vertical distance h between the center of the hole at the tip of the taphole inside the furnace and the tip of the upper surface of the protrusion of the taphole brick, the smaller the slag index. Is rising. In particular, by setting h to 1 m or less and setting the upper slope of the protrusion of the taphole brick to an elevation angle of 45 degrees or less from the furnace core to the furnace wall, the slag index becomes 0.9 (90% of tapping time).
Outflow of molten slag is observed in the above period). Further, by setting h to 0.7 m or less, extremely good tapping slag close to slag index 1 can be achieved.

For the reasons described above, the upper surface of the protruding portion inside the furnace of the taphole brick is formed from the core to the furnace wall so as to have an elevation angle of 45 degrees or less, and the taphole and the protruding portion of the taphole brick are formed. By setting the distance h from the upper end to 1 m or less, a free space can be easily formed in front of the taphole,
A stable tapping residue can be achieved.

[0035]

EXAMPLE In a blast furnace with an inner volume of 5100 m ³ , the upper surface of the inside of the taphole brick was formed at an elevation angle of 40 degrees from the core to the furnace wall. The vertical distance between the center and the top end of the taphole brick protrusion was 0.7 m.

The average slag index for one year and six months after burning is 0.97, which maintains a good tapping residue. Therefore, it is not necessary to take an operation action such as a reduction in the amount of air blown due to an increase in the amount of slag retained in the furnace, and stable blast furnace operation is continued.

[0037]

As described above, according to the present invention, a region (free space) in which a large core coke layer does not always exist in front of the taphole inside the furnace can be stably maintained. Therefore, the taphole brick according to the present invention reliably reduces the amount of residual iron slag on the hearth and at low cost, and contributes to the stable operation of the blast furnace.

[Brief description of the drawings]

FIG. 1 is a view showing a situation in front of a taphole inside a furnace;
(A), when the taphole brick according to the present invention is provided,
(B) is a case where a conventional taphole brick is provided.

FIG. 2 is a schematic view showing the inside of a lower part of a blast furnace.

FIG. 3 is a view showing a half-cut cylindrical model of a hearth.

FIGS. 4A and 4B are diagrams showing experimental results using a model, and FIG.
Is the relationship between the free space position and the residue ratio,
(B) is a diagram for explaining a change in the position of a free space.

5A and 5B are diagrams illustrating a flow of pseudo slag in front of a pseudo taphole inside the furnace, where FIG. 5A shows a case where the pseudo taphole is completely covered with beads, and FIG. This is the case when there is free space along the wall.

FIGS. 6A and 6B are views for explaining the size of a free space in a model hearth, where FIG. 6A is a longitudinal section and FIG.

FIG. 7 is a view showing the relationship between the size of a free space existing in front of the inside of a taphole furnace and the amount of residue.

FIG. 8 is a diagram for explaining the effect of the size (θ) of free space on the amount of residue in front of the taphole inside the furnace;
(A) is when θ is 180 ° (b), θ is 15 ° (c), and θ is 0 °.

FIG. 9 is a diagram showing the effect of taphole brick shape on tapping slag in a test blast furnace, where (a) shows the relationship with the slag index (slagging amount), and (b) shows the relationship of (a). It is a figure explaining a horizontal axis.

[Explanation of symbols]

Reference Signs List 1 tap hole (through hole) 2 liquid level of hot metal 3 liquid level of slag 5 coke packed bed (furnace coke layer) 6 blast furnace hearth 7 tuyere 8 model hearth 9 bead (bead filled layer) 10) Free space (area where no coke layer exists) 11 Pseudo hot metal (liquid Freon) 12 Pseudo slag (oil) 13 Pseudo tap hole 16 Raceway 17 Mud material 18 Tap hole brick 20 Wire mesh 21 Top surface of oil 22 Liquid Freon top surface

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Shiro Watanabe 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Corporation (72) Inventor Yoshitaka Sawa Yoshikawa 1-cho, Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Technical Research Institute (72) Inventor Hideo Oide 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Corporation Technical Research Center F term (reference) 4K015 BA03

Claims (1)

[Claims] 1. A blast furnace comprising a refractory brick-stacked structure having a through-hole for extracting hot metal and slag staying in a blast furnace to the outside of the furnace, and having a protruding portion on the hearth from the furnace wall to the inside of the furnace. An iron brick, wherein an upper surface of the protruding portion has a slope of 45 degrees or less with respect to horizontal from a core side to a furnace wall side, and the center of the through hole on a furnace inner side surface of the protruding portion. A taphole brick for a blast furnace, wherein a vertical length from a top surface of the protrusion to a furnace core side end is 1 m or less.