JP2000256714A - Device for controlling iron tapping slag in blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for controlling the iron tapping time by stabilizing the balance of iron tapping slag and reducing the number of iron tappings. SOLUTION: Tuyere diameter of a tuyere 2 above an iron tapping hole 7 is made to larger than the tuyere diameter of the other tuyere so that the blasting quantity from the tuyere 2 above the iron tapping hole can relatively be increased to the blasting quantity from the other tuyere and also, a flow-rate control valve is interposed at least in the tuyere 2 above the iron tapping hole. When the tapping slag quantity from the iron tapping hole 7 is increased, the blasting quantity from the tuyere 2 above the iron tapping hole 7 is relatively increased to the blasting quantity from the other tuyere and thus, the space 6 between the coke packing layer 4 and the mud piling layer 5, is widened to improve the fluidity of the molten iron slag 9 therein. On the other hand, when the tapping slag quantity is reduced, the blasting quantity from the tuyere 2 above the iron tapping hole is relatively reduced to the blasting quantity from the other tyuere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace tapping control apparatus for discharging hot metal in a blast furnace together with slag from a taphole as tapping slag.

[0002]

2. Description of the Related Art In a blast furnace, generally, coke, ore, etc. are charged from above and hot air is blown from a tuyere provided at a lower part of the furnace, so that a so-called raceway in front of the tuyere is used for combustion. A similar temperature rise occurs, causing the ore to melt and flow down to the hearth as hot metal and slag. Molten slag is literally slag other than hot metal, also called slag,
Generally, due to the specific gravity, hot metal accumulates below the slag. The hot metal and the slag stored in the hearth of the blast furnace as described above (hereinafter, also simply referred to as the slag) are discharged from the tap hole formed at the lower end of the furnace wall as tapping slag.

[0003] As a conventional control method for discharging the tapping residue, for example, there is a method described in Japanese Patent Publication No. 63-65730. This conventional technique relatively controls the amount of air blown from the tuyere and the taphole depth.For example, when the taphole depth becomes shallow, the amount of air blown from the tuyere is reduced. It is said that the gas flow near the taphole becomes inactive, slag adheres to the vicinity of the taphole, and the taphole depth increases. Also, in the final stage of tapping, when gas is blown out from the taphole, so-called roughening, the amount of hot metal slag stored in the hearth is reduced by reducing the amount of air blown from the tuyere. That is, it is stated that the liquid level can be stabilized and gas blowing can be suppressed. When the tapping operation is completed, a filler called a mud is pushed into the taphole and closed.

[0004]

As will be described later, in the tapping operation in a blast furnace, the greatest goal is to discharge a stable tapping amount over a long period of time. Conversely, this is equivalent to reducing the number of tappings when the same tapping amount is required. However, in the conventional tapping slag control method, when the amount of air blown from the tuyere is reduced in a rough state at the end of tapping, gas blowing can be suppressed, but the actual tapping time cannot be lengthened. . In other words, if the amount of air blown from the tuyere is reduced so as to increase and stabilize the amount of tapping slag after the roughing state, the gas blowing is suppressed, but the amount of tapping slag also decreases. The tap hole is clogged with mud as stable tapping slag is not expected. However, in the hearth portion of an actual blast furnace, molten iron or slag (especially slag) that is not discharged continues to be stored, and the balance of tapping slag may be lost. Therefore, so-called lapping is performed, in which a plurality of tapping holes are formed and tapping is performed from two or more locations. When lapping is performed in this manner, a large amount of tappings is discharged this time, so that the molten tappings in the hearth decreases in a short time, and the tapping operation is completed in a short time.
As a result of this repetition, the higher the ratio of the amount of discharged hot metal to the whole, that is, the higher the tapping ratio, and the more the production is to be increased, the more the number of lap tappings and the number of tappings increase. The result is that it is shortened.

According to the present invention, the tapping time itself is lengthened by reducing the number of tappings by securing a stable tapping amount, and the amount of mud used to close the taphole and the taphole depth are controlled. It is an object of the present invention to provide a blast furnace tapping residue control device capable of adjusting the blast furnace tapping temperature.

[0006]

In order to solve the above problems, a blast furnace tapping control apparatus for a blast furnace according to claim 1 of the present invention increases or decreases the amount of tapping slag discharged from a tap hole of a blast furnace. A control device for controlling, in order to adjust the space between the coke packed layer and the mud deposition layer in the vicinity of the tap hole, the tuyere diameter of the tuyere above the tap hole, the other tuyere A flow control valve is provided at least in the tuyere above the tap hole, the flow control valve being interposed.

A blast furnace tapping control apparatus according to a second aspect of the present invention is a control apparatus for increasing or decreasing an amount of tapping slag discharged from a tapping hole of a blast furnace, wherein In order to adjust the space between the coke packed bed and the mud deposition layer in the vicinity, all the tuyeres are provided with flow control valves. Here, as will be described later, these inventions relate to a method in which hot metal and slag (hot metal slag) are provided between a coke packed layer below a tuyere and a mud deposition layer in which a tap hole is opened.
It was made by paying attention to the space where the fluid flows. That is, if this space is large, the fluidity of the molten iron slag is improved, so that the amount of tapping slag increases. Conversely, if the space is small, the fluidity of the molten iron slag decreases, and the amount of molten tapping slag decreases. This space can be adjusted by controlling one or both of the coke packed layer and the mud deposition layer. Therefore, in the present invention, the state of the coke packed bed is controlled by controlling the amount of air blown from the tuyere above the taphole relative to the amount of air blown from other tuyeres. Thus, the space between the coke packed layer and the mud deposition layer is adjusted. That is, when increasing the amount of tapping slag discharged from the taphole, the amount of air blown from the tuyere above the taphole is relatively increased with respect to the amount of blown air from other tuyeres. This increases the space between the coke packed layer and the mud deposition layer. Further, when reducing the amount of tapping slag discharged from the taphole, the amount of air blown from the tuyere above the taphole is reduced relative to the amount of air blown from other tuyeres. This reduces the space between the coke packed layer and the mud deposit. The configuration required for the relative control of the tuyere blowing amount is the present invention.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a blast furnace tapping residue control apparatus according to the present invention will be described in detail with reference to the drawings.
First, FIG. 1 shows a longitudinal sectional view from the tuyere of the blast furnace of the present embodiment to the hearth. In the lower part of the furnace wall 1 of the blast furnace, a tuyere 2 as a hot air blowing port is provided over the entire circumference thereof. The tuyere 2 is heated at 1000 ° C. by a hot air stove (not shown).
The hot air blown into the blast furnace from the tuyere 2 is supplied with the gas heated to a degree, and forms a high heat space called a raceway 3 in the coke packed bed 4 described later.

On the other hand, coke, ore, and the like charged from above the blast furnace form a coke packed layer 4 consisting essentially of coke below the tuyere 2. This is because the ore is melted by the high-temperature heating in the raceway 3 and flows down to the hearth as hot metal and slag, that is, hot metal slag 9. The hearth is covered with a mud made of a refractory material to form a mud deposition layer 5. This mud is used to close a tap hole 7 formed from the furnace wall to the mud deposition layer 5, and the mud deposition layer 5 protects the original hearth.

When a certain amount of molten iron slag 9 accumulates on the hearth of the blast furnace, that is, on the mud deposit 5, the molten iron slag 9 penetrates from the furnace wall 1 to the mud deposit 5 through the tap hole 7. The molten iron slag 9 is discharged from the hole 7 as tapping slag. Next, an example of the layout of the tuyere is shown in FIG. In the blast furnace of the present embodiment, three tap holes from the first tap hole 7 (a) to the third tap hole 7 (c) are used. On the other hand, the furnace wall is provided with a total of 33 tuyeres 2 over the entire circumference. All tuyere 2
Are connected to a common hot air supply source, so that sufficient tuyere 2 can blow out sufficient hot air.

In the present embodiment, the tuyere 2 (a) above each tap hole, specifically, above the first tap hole 7 (a), is disposed so as to sandwich it. First and third
The fifteenth and sixteenth tuyeres 2 arranged above and above the three tuyeres 2 (a) and the second taphole 7 (b).
(A) The tuyere diameters of the eighteenth and nineteenth tuyeres 2 (a) disposed so as to sandwich the third taphole 7 (c) above the other tapholes 2 (c) b), the air flow rate from the tuyere 2 (a) above the tap hole is
The amount of air blown from the other tuyere 2 (b) can be relatively increased. However, since there is basically only one tap hole 7 used for tapping work, for example, the tuyere 2 having a large tuyere diameter above the tap hole is used.
In (a), a flow control valve 8 for adjusting the amount of hot air is interposed.

As will be described later, in this embodiment,
The amount of air blown from the tuyere 2 (a) above the taphole is increased or decreased relative to the amount of air blown from the other tuyere 2 (b), or both are controlled equally. The layout of the tuyere 2 is, for example, as shown in FIG.
May be as shown in FIG. That is, all tuyere 2
And the tuyere diameter of the tuyere 2 (a) above the taphole is made substantially the same, and the flow control valves 8 are interposed in all tuyeres. Therefore, for example, if the amount of air blown from the tuyere 2 (a) above the tap hole is increased relatively to the amount of air blown from the other tuyere 2 (b), the amount of air above the tap hole is increased. Tuyere 2 (a)
Open the flow control valve 8 interposed in the
What is necessary is just to close the flow control valve 8 interposed in (b). Conversely, for example, if the amount of air blown from the tuyere 2 (a) above the tap hole is reduced relatively to the amount of air blown from the other tuyere 2 (b), the amount of air blown above the tap hole is reduced. What is necessary is just to close the flow control valve 8 interposed in the tuyere 2 (a) and open the flow control valve 8 interposed in the other tuyere 2 (b). In addition, in order to make the amount of air blown from all tuyeres 2 equal, the openings of the flow control valves 8 of all tuyeres 2 may be made the same.

Next, the flow control valve provided in the tuyere will be described with reference to FIG. This flow control valve can withstand use for a long time even under high temperature, high pressure and high flow velocity using ceramic as the valve body 8a. The flow control valve is provided with the extension 12 of the blower branch pipe 11 and the blow pipe 13 in the tuyere 2. It is integrated with the short spherical tube 15 between the lower bend 14 for connection. The opening degree of the flow control valve 8 can be changed manually or continuously by an actuator, and the air flow rate ratio characteristic is as shown in FIG. The air volume ratio is expressed as a percentage of a value obtained by dividing the air volume at each valve opening angle (opening degree) by the fully opened air volume.

Next, the principle of the tapping residue control method of the present embodiment will be described. First, the ideal of extending the tapping slag time while securing a stable tapping slag amount will be described with reference to the tapping slag amount characteristic diagram of FIG. That is, for example, if a stable amount of tapping slag can be expected, from the viewpoint of the durability of the blast furnace and the material supply, it is desirable that the amount of hot metal and slag, that is, the amount of ironmaking slag, is constant. However, even in actual operations, the amount of ironmaking slag is kept constant. In other words, for example, if the amount of ironmaking slag is to be increased, the furnace temperature must be increased, so that the durability of the furnace body decreases, and the raw materials also need to be supplied in an increased process. On the other hand, typical tapping residue characteristics appear as shown in FIG. That is, when no operation is performed, the tapping hole diameter increases due to heat-induced wear with the elapse of tapping, so that the tapping slag amount increases in the later stage of tapping. In order to bring this closer to a constant amount of tapping and to extend tapping time, the initial tap hole diameter must be reduced. It will be less than the amount of iron slag. The tapping time can be extended by bringing the actual tapping amount close to the ironmaking amount, and by stabilizing the tapping amount, the tapping time can be greatly extended.

On the other hand, as described in JP-B-63-65730, the roughening state occurs at the end of tapping because the amount of air blown from the tuyere is too large and the internal pressure is high. It is thought that this causes the liquid level of the molten iron slag on the hearth to be wavy, so that when it becomes rough, the amount of air blown from the tuyere is reduced and gas blowing is suppressed. I was However, in this case, although gas blowing is certainly suppressed, the tapping amount itself is reduced, and the tapping operation is terminated because a stable tapping amount cannot be obtained. In other words, there has been a contradiction that although the amount of air blown from the tuyere has been reduced in an attempt to increase the amount of tapping slag, the amount of tapping slag substantially decreases. Further, if the tuyere diameter itself is reduced in order to reduce the amount of air blown from the tuyere, there is also a problem that it is not possible to increase the amount of air blow for increasing the production volume. The tapping operation is terminated by closing the taphole with a mud.

The present inventors have conducted intensive studies on this contradiction, and as a result, have obtained the following findings and developed the present invention.
In other words, the small amount of tapping slag, that is, the poor tapping ability, means that the flowability of the hot metal slag near the taphole in the furnace is poor. Is low or there is something that becomes a resistance. Of these, in the actual operation, the temperature of the molten iron slag is controlled so as to be almost constant, and the temperature of the molten metal from the tap hole with poor waste metal slag quality is not always low. For example, as shown in FIG. 1, the fluidity of the hot metal slag 9 in the space 6 between the coke packed bed 4 and the mud deposition layer 5 in the hearth portion where the hot metal slag is stored, Was found to be involved. However, the space 6 includes not only a space between layers, but also a space such as a gap between cokes which does not substantially form a layer. When the space 6 is large, the fluidity of the molten iron slag 9 is improved, and the amount of tapping slag is increased (the molten iron slag property is improved). Conversely, when the space 6 is small, the fluidity of the molten iron slag 9 is reduced and the amount of tapping slag is reduced (the iron slag property is reduced). Regarding this fluidity, as will be described in detail later, mainly a viscous slag is more likely to be affected, but in any case, if this space can be controlled, the amount of tapping slag can be freely adjusted. It turned out that it could be adjusted.

The element constituting the space 6 is, of course, the relative positional relationship between the coke filling layer 4 and the mud deposition layer 5. For example, in FIG. 1, if the end of the tapping hole side of the coke packed layer 4 can be displaced to the position shown by the broken line, the space 6 between the coke packed layer 4 and the mud deposit layer 5 is expanded. vice versa,
Even when the end of the mud deposit layer 5 at the tap hole 7 side at the coke filling layer 4 side is displaced to the position shown by the broken line, the space 6 between the mud deposit layer 5 and the coke filling layer 4 expands. Among these, the former is made possible by increasing the amount of air blown from the tuyere 2 (a) above the taphole, relative to the amount of air blown from the other tuyere 2 (b). I understood. That is, the amount of air blown from the tuyere 2 (a) above the tap hole is reduced by the other tuyeres 2 (a).
With respect to the air flow from (b), if it is relatively increased,
The entire coke packed bed 4 attempts to move away from the tap hole 7, or the coke packed layer 4 on the tap hole side.
When the coke packed layer 4 is compressed to be dense, the tap hole side end of the coke packed layer 4 moves away from the tap hole 7 and the space 6 between the tap hole 7 and the mud deposit layer 5 increases.

For this reason, in the present embodiment, as shown in FIG. 2, the tuyere diameter of the tuyere 2 (a) above each tap hole is larger than the tuyere diameter of the other tuyere 2 (b). By setting, the amount of air blown from the tuyere 2 (a) above the taphole can be relatively increased with respect to the amount of air blown from the other tuyeres 2 (b). In addition, at times other than tapping slag, as described above, it is desirable to stabilize the ironmaking slag in the furnace as much as possible, and to protect the furnace body as described below, It is necessary to make the air volume from the tuyere 2 (a) above the hole equal to the air volume from the other tuyeres 2 (b). Furthermore, if the amount of mud used is to be reduced as described later, the tuyere 2
It is also necessary to reduce the amount of air blown from (a) relative to the amount of air blown from other tuyeres 2 (b). For this reason, in the present embodiment, at least the tuyere 2 (a) above each tap hole is provided with the flow control valve 8 to reduce the air flow rate.
The amount of air blown from the other tuyere 2 (b) can be relatively increased or decreased.

Further, since the relationship of the air volume between the tuyeres is relative, for example, as shown in FIG. 3, the tuyere diameters of all the tuyeres 2 are set to the values above the tap holes in FIG. And the tuyere 2 (a) having the tuyere diameter equal to that of the tuyere 2 (a), and all of the tuyeres 2 with the flow control valves 8 interposed therebetween, as described above, from the tuyere 2 (a) above the tap hole at the time of tapping. Air volume of other tuyere 2
(B), relative to the amount of air blown, at other times, for example, equalize the amount of air blown from all tuyeres 2 or from the tuyere 2 (a) above the taphole. The air volume may be relatively reduced with respect to the air volume from the other tuyere 2 (b).

On the other hand, of the latter, ie, the mud deposition layer 5,
It is not easy to displace the end of the coke packed bed 4 at the tap hole 7. Therefore, in order to enhance the fluidity of the molten iron slag 9 up to the tap hole 7, it is conceivable to simply make the tap hole depth shallow, that is, to open the tap hole 7 at a position far from the coke packed bed 4. . However,
In a general blast furnace, for example, the position at which a tap hole is opened and the angle thereof are almost restricted due to a tapping gutter or the like, and it is difficult to change the opening portion of the tap hole. Therefore, when it is desired to increase the amount of tapping slag as a whole, that is, in order to make the taphole depth shallow, the end of the mud deposit layer 5 on the coke filling layer 4 side at the taphole site is filled with the coke. Layer 4
When it is desired to increase the space 6 between them, the amount of mud used to close the tap hole 7 (this is referred to as mud pushing amount) may be reduced. Conversely, when you want to reduce the tapping slag volume as a whole, that is, to increase the taphole depth,
When the end of the mud deposition layer 5 at the tap hole side near the coke packed layer 4 is brought closer to the coke packed layer 4 and the space 6 between them is to be reduced, the mud pushing amount may be increased.

Further, by using these combinations, the amount of mud used, that is, the so-called basic unit can be reduced. That is, for example, as described above, the amount of air blown from the tuyere 2 (a) above the taphole is relatively increased with respect to the amount of air blown from the other tuyere 2 (b). When the space 6 between the layer 4 and the mud deposit layer 5 is enlarged to increase the fluidity of the hot metal slag 9, the mud deposit layer 5 is exposed to the high-temperature hot metal slag 9, and the mud refractory in that portion is easily worn out. . Therefore, for example, when it is not necessary to increase the amount of tapping slag or at the time other than the tapping operation, for example, the amount of air blown from the tuyere 2 (a) above the taphole is changed to the other tuyere 2 (b). Or less relative to the amount of air blown from the furnace, making it difficult for the mud deposit layer 5 at the tap hole 7 to be exposed to the hot metal slag 9 having good fluidity, thereby preventing its wear. be able to. Furthermore, when the coke filling layer 4 is brought closer to the mud deposition layer 5,
The lower end of the coke filling layer 4 is buried in the mud deposition layer 5. In this case, the mud deposit layer 5 is protected from the molten iron slag 9 by the coke filling layer 4, and the wear of the mud deposit layer 5 is further suppressed and prevented. As described above, when it is not necessary to increase the amount of tapping slag or at the time other than tapping operation, for example, the amount of air blown from the tuyere 2 (a) above the taphole is changed to the other tuyere 2
By making the air volume equal to or less than the air volume from (b), the wear of the mud deposition layer 5 is suppressed and prevented, and the mud intensity is reduced while securing the taphole depth. It becomes possible.

So far, the space between the coke packed layer and the mud deposit layer has been described as affecting the fluidity of the hot metal slag as a whole. Is easier to receive. This depends on the fact that the molten metal exists on the molten iron due to the specific gravity, and that the viscosity of the molten metal is much higher than the viscosity of the molten iron. In other words, by controlling the size of the space between the coke packed bed and the mud deposition layer, the balance between the expulsion properties and the slagging property, that is, the tapping slag balance, can be controlled.

As mentioned above, in the conventional tapping slag control method in which the amount of air blown from the tuyere is reduced during tapping operation, the space between the coke packed layer and the mud deposit layer becomes small, Particularly, while the fluidity of the slag is reduced and the slagging property is deteriorated, the hot metal which is not significantly affected by the size of the space is discharged more and more. Therefore, in this state, the tapping operation is stopped, and the ratio of the slag stored in the hearth gradually increases until the next tapping, as compared with the hot metal. Therefore,
After repeated tapping operations, the tapping residue balance is lost,
A large amount of slag needs to be discharged. For this reason, lapping and tapping the diameter of the tapping hole as described above are performed, and the slag in the furnace is simultaneously discharged. Therefore, there still remains a problem that the number of taps increases and the work load also increases.

However, as described above, the space between the coke packed layer and the mud deposit layer has a greater influence on the fluidity of the slag than the fluidity of the molten iron, and therefore, the space between the molten slag and the desired molten tapping slag balance may not be achieved. For example, when the iron discharge property is good and the waste property is poor, the amount of air blown from the tuyere above the taphole is increased relatively to the amount of air blown from other tuyeres, In addition to increasing the amount of tapping slag, the slagging property can be improved and the tapping slag balance can be brought close to a desired state. Conversely, for a desired tapping slag balance, for example, when the tapping performance is poor and the tapping performance is good, the amount of air blown from the tuyere above the taphole is changed to the amount of air blown from other tuyeres. On the other hand, by relatively decreasing, not only the amount of tapping slag can be reduced, but also the tapping performance can be improved and the tapping slag balance can be brought close to a desired state. in this way,
The true purpose of the tapping slag control method of the present embodiment is that, by controlling the tapping slag balance, for each tapping operation, a stable tapping slag amount can be secured for a long time, As a result, the number of tappings decreases and the tapping time increases.

Next, the operation of the tapping residue control method of the present embodiment will be described with reference to various experimental results. FIG.
The number of tappings (Tap. No in the figure) is the ath time or later, and the tuyere diameters of the 18th and 19th tuyeres above the third tapping hole in FIG. 2 are the tuyere diameters of the other tuyeres. From φ120mm to φ1
By expanding the diameter to 40 mm and controlling the flow control valve except during tapping, the air volume from the 18th and 19th tuyeres is made equal to the air volume from the other tuyeres, 3
During the tapping operation from the tap hole, the flow rate control valve is fully opened, so that the amount of air blown from the 18th tuyere and the 19th tuyere is reduced by about 1 to the amount of air blown from other tuyeres. It is designed to increase about 0.5 times. In addition, as shown in FIG. 7c, the average tapping time x
^- is 191 minutes, a time after the average tapping time x ^- 198
Minutes, the tapping time itself has not changed much.

Here, using the evaluation index called the slag index, the tapping states before and after the a-th run are compared. First, the slag index is a ratio of the slag time to the slag time (= slag time / slag time). The tapping time is literally the time from when a taphole is opened to when it is closed. The tapping time is the time from when tapping slag accumulates to a certain level in the tapping trough until the tapping hole is closed. In other words, the slag index may be considered to evaluate the amount of tapping slag particularly at the initial stage of tapping, and in the tapping slag amount characteristic diagram of FIG.
This is an evaluation index for determining whether the amount of tapping slag in the initial stage of tapping can be approximated to the amount of tapping slag. FIG. 7A shows a histogram of the slag index before the tapping number a, and FIG. 7B shows a histogram of the slag index after the tapping number a. From these, the blowing rate from the tuyere above the taphole, relative to the blowing rate from the other tuyeres, after the tapping frequency a times increased relatively, the high frequency of the slag index is large You can see that it has become. Here, the fact that the slag index is large means that the amount of tapping slag is large from the beginning of tapping, so that the tapping time itself may be shortened when considered normally. However, since the tapping time is not shortened even after the tapping number a, the amount of air blown from the tuyere above the taphole during the tapping operation is compared with the amount of air blown from other tuyeres. As a result, the space between the coke packed layer and the mud deposit layer is increased to increase the fluidity of the molten iron slag, thereby increasing the amount of molten slag from the initial stage of tapping and discharging. It can be seen that a high tapping ratio can be achieved by securing the pig time.

Next, FIGS. 8 to 13 show the number of tapping times (Tap.
o) At the 20th to 50th times, the amount of air blown from the tuyere above the tap hole is equal to the amount of air blown from other tuyeres,
At the 0th to 60th times (the shaded portion in the figure), the amount of air blown from the tuyere above the taphole was 3 times the amount of air blown from the other tuyeres.
When the tapping frequency is reduced to about 0% and the tapping frequency is 60 or more, the airflow from the tuyere above the taphole is returned to the same level as the airflow from other tuyeres. Indicated.

First, FIG. 8 shows the change of the slag index for each tapping operation. As described above, the amount of air blown from the tuyere above the taphole, with respect to the amount of air blown from other tuyeres,
When the relative decrease, the space between the coke packed bed and the mud sedimentary layer becomes smaller, and the fluidity of the hot metal slag in the space decreases, so that the amount of tapping slag at the initial tapping time also decreases, Since the accumulation of tapping slag to the predetermined level of the tapping gutter is delayed, the slag index is small at the 50th to 60th tapping times. Also, it can be seen that this effect gradually becomes larger. On the other hand, when the amount of air blown from the tuyere above the taphole is equalized to the amount of air blown from other tuyeres at the 60th tapping time, the slag index increases immediately. Accordingly, it can be seen that the slag index has a high responsiveness to the control for increasing the amount of air blown from the tuyere above the taphole.

FIG. 9 shows the pig iron balance.
FIG. 10 shows the slag balance discharged. The balance is a value obtained by subtracting the input amount from the amount discharged in each tapping operation. In other words, if the balance is a positive value, the discharged amount is larger than the input amount, so that the dischargeability is good, and if the balance is a negative value, the dischargeability is poor. As is clear from these, the air volume from the tuyere above the taphole
If the amount of air blown from other tuyeres is relatively reduced, the space between the coke packed layer and the mud deposition layer becomes smaller, and slag waste greatly affected by the fluidity in this space. The ironability, which is not significantly affected, is relatively improved. Further, in this embodiment, when the amount of air blown from the tuyere above the tap hole is equal to the amount of air blown from other tuyeres, both the iron balance and the slag balance are balanced near zero. From this, conversely, if the amount of air blown from the tuyere above the taphole is relatively increased with respect to the amount of air blown from other tuyeres, the waste property is improved and the Is expected to decrease.

Next, FIG. 11 shows a change in tapping time for each tapping operation. With the change of the slag index and the slag balance as described above, in the 50th to 60th tapping times, the state in which tapping slag is difficult is continued, and the tapping time tends to be shortened as a whole. Considering this and the slag balance, conventionally, the control for reducing the amount of air blown from the tuyere above the tap hole relative to the amount of air blown from the other tuyere has been performed by the following method. It is understood that the slag accumulates with each operation, and eventually the slag in the furnace must be discharged all at once due to lapping and tapping.

Next, FIG. 12 shows a change in tap hole depth, and FIG. 13 shows a change in tap hole depth per unit mud pushing amount. FIG. 12 shows that the tap hole depth was not intentionally changed, and FIG. 13 shows that the tap hole depth per unit mud pushing amount became larger with respect to the unchanged tap hole depth. As a result, the amount of mud pushing used as a result is gradually reduced. In other words, as described above, if the amount of air blown from the tuyere above the taphole is reduced relatively to the amount of air blown from other tuyeres, the space between the coke packed layer and the mud deposition layer will be reduced. The mud deposits are less likely to be exposed to the hot metal slag, or are covered and protected by the coke packed layer, so that the mud deposits are less likely to be worn away and the tap holes are reduced accordingly. The amount of pressing the mud used for closing is small. This effect is becoming increasingly significant. On the other hand, if the amount of air blown from the tuyere above the taphole is equal to the amount of air blown from other tuyeres, the taphole depth per unit mud pushing amount is immediately reduced. It can be seen that the response of the mud deposition layer to wear when the space between the filling layer and the mud deposition layer is increased is high.

[0032] Considering this in reverse, if the amount of air blown from the tuyere above the tap hole is not intentionally changed with respect to the amount of air blown from other tuyeres, for example, When it is desired to increase the amount, the space between the coke packed layer and the mud sedimentary layer should be increased, and in such a case, the mud pressing amount should be reduced to reduce the tap hole depth. Good. Conversely, when it is desired to reduce the amount of tapping slag, it is only necessary to increase the mud pushing amount in order to reduce the space between the coke packed bed and the mud deposition layer to increase the taphole depth.

Next, FIG. 14 shows changes after and before the control of the amount of air blown from each tuyere as described above. FIG. 14A shows the result of performing the above-described air volume control from N months in each of the consecutive months from A to X.
Shows the tapping ratio, FIG. B shows the number of lap taps, FIG. C shows the tapping frequency, and FIG. D shows the mud intensity. As is clear from these, the conventional control method has gradually increased the number of lapping tappings in response to a demand for a high tapping ratio from K months to W months. This is due to the fact that the slag accumulates in the furnace and discharges it as a result of reducing the air volume from the tuyere and giving priority to the discharge of hot metal, regardless of the tapping balance. On the other hand, from the N months when the control of the present embodiment was performed, by appropriately maintaining the tapping slag balance, accumulation of the slag was avoided, and the number of times of lap tapping could be reduced.

Also, with the decrease in the number of lapping tappings,
By appropriately maintaining the tapping amount and the tapping balance, the tapping frequency is reduced, which indicates that the tapping time can be extended under a high tapping ratio. Also, except when tapping or when a high tapping amount is not required, the amount of air blown from the tuyere above the taphole is reduced relatively to the amount of air blown from other tuyeres. As a result, the space between the coke packed layer and the mud deposition layer was reduced, thereby suppressing the wear of the mud deposition layer.As a result, the mud intensity was reduced and the cost was reduced. did it. In addition, by stabilizing the operation as a whole, the life of the furnace body could be further extended.

[0035]

As described above, according to the tapping slag control apparatus of the present invention, the tuyere diameter of the tuyere above the taphole is made larger than the tuyere diameter of the other tuyeres and at least the tapping A flow control valve is interposed in the tuyere above the hole, or a flow control valve is interposed in all the tuyeres. By increasing relative to the amount of air blown from, the space between the coke packed layer below the tuyere and the mud deposition layer is increased to improve the flowability of hot metal and slag, Since the amount of tapping slag from the tap hole can be increased, for example, even when the amount of tapping slag tends to decrease at the beginning of tapping or at the end of tapping, the amount of tapping slag is controlled in the increasing direction, and It is possible to stabilize the amount of slag, reduce the number of tapping times, thereby extending the tapping time itself, Intentionally promote wear of the mud deposited layer by the upper and the hot metal and 溶滓, it is also possible to shallow the tap hole depth. In addition, the amount of air blown from the tuyere above the taphole is reduced relatively to the amount of air blown from other tuyeres, so that the coke packed layer below the tuyere and the mud Since the space between the tapholes and the slag can be reduced to reduce the flowability of the slag, thereby reducing the amount of the slag from the taphole, for example, the amount of the slag increases in the later stage of the tapping. At the same time, it is controlled in a decreasing direction to stabilize the tapping amount and reduce the number of tapping times, so that the tapping time itself can be lengthened and the fluidity of the hot metal and the slag can be improved. By lowering, the wear of the mud deposit layer can be intentionally slowed down, thereby making it possible to reduce the amount of mud used or to increase the taphole depth.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state from a tuyere of a blast furnace to a hearth portion.

FIG. 2 is an explanatory diagram showing an example of a tap hole and a tuyere.

FIG. 3 is an explanatory view showing another example of a taphole and a tuyere.

FIG. 4 is an explanatory diagram of a flow control valve used in FIG. 2 or FIG.

FIG. 5 is an explanatory diagram of characteristics of the flow control valve of FIG. 4;

FIG. 6 is an explanatory diagram of a general tapping amount.

FIG. 7 is an explanatory view before and after changing a tuyere air supply amount,
(A) is a histogram showing the frequency rate of the slag index before changing the tuyere air volume, (b) is a histogram showing the frequency rate of the slag index after changing the tuyere air volume, (c)
FIG. 4 is an explanatory diagram of tapping time for each tapping before and after changing the tuyere blowing amount.

FIG. 8 is an explanatory diagram showing a change in a slag index when the tuyere blowing amount is changed.

FIG. 9 is an explanatory diagram showing a change in the pig balance when the tuyere blowing amount is changed.

FIG. 10 is an explanatory diagram showing a change in slag balance when the tuyere blowing amount is changed.

FIG. 11 is an explanatory diagram showing a change in tapping time when the tuyere blowing amount is changed.

FIG. 12 is an explanatory diagram showing a change in taphole depth when the tuyere blowing amount is changed.

FIG. 13 is an explanatory diagram showing a change in taphole depth per unit mud pushing amount when the tuyere blowing amount is changed.

FIG. 14 is an explanatory diagram before and after changing a tuyere air supply amount,
(A) is an explanatory diagram showing a change in the tapping ratio before and after changing the tuyere blowing amount, (b) is an explanatory diagram showing a change in the number of lap tapping before and after changing the tuyere blowing amount, and (c). FIG. 7 is an explanatory diagram showing a change in the number of tappings before and after changing the tuyere blowing amount, and FIG. 6D is an explanatory diagram showing a change in mud intensity before and after changing the tuyere blowing amount.

[Description of Signs] 1 is a furnace wall 2 is a tuyere 3 is a raceway 4 is a coke packed layer 5 is a mud deposition layer 6 is a space 7 is a tap hole 8 is a flow control valve 9 is a molten iron slag

Claims (2)

[Claims] A control device for increasing or decreasing the amount of tapping slag discharged from a taphole of a blast furnace, wherein the control device adjusts a space between a coke packed bed and a mud deposition layer near the taphole. The blast furnace characterized in that the tuyere diameter of the tuyere above the taphole is larger than the tuyere diameter of the other tuyeres and at least a tuyere above the taphole is provided with a flow control valve. Tapping residue control device. 2. A control device for increasing or decreasing the amount of tapping slag discharged from a taphole of a blast furnace, wherein the control device adjusts a space between a coke packed bed and a mud deposition layer near the taphole. A tapping control system for a blast furnace, wherein a flow control valve is interposed in all tuyeres.