JP2001294912A - Method for operating blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which the erosion of a refractory brick is not prevented by charging a little quantity of titanium source when a blast furnace is operated because uniform formation of a titanium bear on the surface of a furnace hearth part is difficult. SOLUTION: In case of operating the blast furnace 1 molten iron is tapped off from at least two tapping holes among the tapping holes 7a-7d in order. When the rising speed of the temperature of the furnace hearth part 10 in the blast furnace 1 becomes over a prescribed critical values, the titanium source is charged into the blast furnace 1 so that the titanium concentration in the molten iron tapped off in operation from tapping holes 7a-7d is to be >=0.20 mass %. Thereafter, when the rising speed of the temperature of the tapped-off molten iron in operation exceeds for >=24 hr the rising speed in case of other tapping holes already operated, the use of the holes is limited or stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for operating a blast furnace. More specifically, the present invention effectively generates titanium bears on the hearth of the blast furnace by using as little titanium source as possible, and prevents local erosion of the hearth bricks and hearth side wall bricks constituting the hearth. The present invention relates to a method for operating a blast furnace, which can suppress the operation to extend the operating life of the blast furnace.

[0002]

2. Description of the Related Art FIG. 9 is a perspective view schematically showing a simplified example of a blast furnace 1 which is a large-sized reactor in an iron making process with a part thereof broken.

As shown in FIG. 9, a blast furnace 1 has a furnace port 2 for charging ore and coke into the furnace, a furnace chest 3 for burning coke to reduce and melt the ore, and a furnace. Belly 4
And the morning glory 5 and 4 at 90 ° intervals with respect to the center of the blast furnace 1.
A tap hole 7a for sequentially discharging pig iron provided and provided.
~ 7d and from tuyere 6 to 1000-1200
湯 C hot air is blown into the furnace to burn coke, generate high-temperature reducing gas, and bring it into contact with the ore to generate heat exchange and reduction action on the ore to separate it into slag and pig iron. 8 is provided. The blast furnace 1 shown in FIG.
Is a case in which four tap holes 7a to 7d are provided at 90-degree intervals, but there are also blast furnaces provided with three tap holes at 120-degree intervals. In recent years, the blast furnace 1 has inevitably tended to become larger as a result of promoting its production efficiency. As the size of the blast furnace 1 increases, the blast furnace 1 will be blow-stopped, re-wound, and fired.
A series of renovation costs have also increased significantly. For this reason, the extension of the operating life of the blast furnace 1 has come to directly and significantly affect the cost reduction of the iron making process.

[0004] The timing of blowing off the blast furnace 1 is determined in consideration of social factors such as steel demand and the economy at that time, but technically, it is based on the degree of deterioration of the furnace body 1a of the blast furnace 1. Is determined. The furnace body 1a of the blast furnace 1 is always used under severe conditions of high temperature and high pressure, but when examined in more detail, the aging of the furnace upper part 9a above the tuyere 6
The main causes are wear and thermal stress, etc., caused by the charged materials such as raw materials. On the other hand, the deterioration of the lower furnace part 9b below the tuyere 6
It is considered that the main cause is a heat load due to a high-temperature hot metal flow in the hearth portion 10 that forms the bottom of the pool 8.

[0005] The repair technology of the blast furnace 1 has been remarkably improved in recent years, and the aging furnace body 1a can be repaired by stopping the air from the upper part 9a for a certain period of time. However, regarding the furnace lower part 9b, the hearth part 10
Because of the accumulation of molten iron slag, repair is extremely difficult, and it is almost impossible at present to perform repairs during a temporary outage. For this reason, it is no exaggeration to say that the operating life of the blast furnace 1 is governed by the life of the lower furnace part 9b.

[0006] In the hearth portion 10 constituting the lower furnace part 9b, molten iron slag accumulates, so that the refractory brick of the hearth 10a or the refractory brick of the hearth side wall 10b is locally eroded. One of the key factors governing this local erosion is the hearth 10
, Ie, the heat load caused by the hot metal flow at the bottom of the furnace.

[0007] In order to reduce the heat load due to this hot metal flow,
Generally, for example, a titanium source such as iron sand or titanium oxide (TiO ₂ ) is blended into the charging material, or the titanium source is
From the surface of the refractory brick on the hearth 10a or the refractory brick on the hearth side wall 10b,
Means have been taken to protect these refractory bricks by producing a titanium bare, which is a solid solution. However, always injecting titanium into the blast furnace 1 in order to suppress the wear of the refractory bricks of the hearth 10a and the refractory bricks of the hearth side wall 10b is extremely wasteful and increases the cost of the titanium source. Excessive formation in the hot metal may significantly deteriorate the fluidity of the hot metal and cause a tapping trouble. Further, depending on the state of the hot metal flow, the titanium source blown from the tuyere 6 does not stay in the hearth 10 and the tap holes 7a to 7d are formed without generating a titanium bear.
Could be discharged directly out of the furnace.

On the other hand, recently, in the pig iron present in the basin 8 of the blast furnace 1, a low liquid permeability region in which permeability of molten iron slag is extremely reduced is formed. When the part disappears, the flow of pig iron is activated and the hearth 1
In addition, there are reports that the heat load of the refractory brick increases due to the heat load of 0, and the distribution of the tap hole 7 depends on the distribution state of the furnace in the low liquid permeability area.
Reports that tapping from any of the specific tapholes a to 7d promotes wear of the hearth 10 are described in “Iron and Steel 78 (1992)”, page 1171. And so on.

Japanese Unexamined Patent Publication No. Hei 5-78720 discloses that when the temperature of a thermometer attached to a furnace bottom brick or the rate of temperature rise exceeds a specified level, kish graphite is supplied from a tap hole with a mud gun to the bottom of the furnace. After filling the damaged part of the impervious layer, the mud is filled into the tap hole to allow the quiche graphite to reach the break in the impervious layer and prevent hot metal from flowing into the bottom of the furnace. An invention for preventing erosion of a refractory has been proposed.

Japanese Patent Application Laid-Open No. 9-227909 discloses that a tracer made of Co, Ni, Ti or the like is blown into a blast furnace from a tuyere closest to a specific tap hole, and a tracer in the discharged hot metal from the start of blowing. The elapsed time until the concentration increases (20
An invention has been proposed in which the use of the tap hole is restricted when the ratio exceeds (tap ratio), thereby suppressing wear of the hearth portion without charging the titanium source into the furnace.

[0011]

However, Japanese Patent Application Laid-Open No. 5-78 / 1994
The invention proposed by Gazette 720 discloses that the refractory material in the hearth can only be filled when the quiche graphite can be filled with a mud gun, i.e., when the vanishing part of the low liquid permeability area exists directly below the taphole. Erosion cannot be prevented, and erosion cannot be prevented for the disappearance portion of the low liquid permeability region existing in a portion other than immediately below the taphole.

On the other hand, in order to carry out the invention proposed in Japanese Patent Application Laid-Open No. 9-227909, it is necessary to frequently restrict the use of tap holes. However, in the normal operation of a blast furnace, tapholes connected to tapholes are regularly repaired, so one or two of the four tapholes are It will be suspended for this repair. Therefore, if the use of tapholes is frequently restricted, the total tapping amount becomes insufficient, and it is actually difficult to frequently restrict the use of tapholes. Also,
Even if the use of the taphole was restricted according to the present invention and the wear of the hearth was temporarily suppressed, when the use of the taphole was resumed thereafter, the temperature of the hearth increased again. Therefore, erosion of the refractory in the hearth cannot be drastically suppressed.

Here, the present invention has been made in view of the above-mentioned problems of the conventional technology, and it has been proposed that a titanium bear having a brick protecting effect can be effectively removed from a furnace floor while continuing operation of a blast furnace. In other words, by forming on the surfaces of the refractory bricks of the hearth and hearth side walls, the erosion of the refractory bricks in the hearth is prevented by charging a small amount of titanium source without being affected by the repair work of the hot metal gutter. It is an object of the present invention to provide a method for operating a blast furnace, which can increase the operating life of the blast furnace and significantly reduce the cost of the iron making process.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a method for operating a blast furnace by discharging hot metal sequentially from at least two or more tapholes among a plurality of tapholes provided in a blast furnace.
After the temperature of the hearth of the blast furnace or the rate of increase in the temperature exceeds a predetermined critical value, the hot metal is discharged when the temperature exceeds the critical value by introducing a titanium source into the furnace of the blast furnace. After setting the titanium concentration of hot metal that is tapped from a taphole that has been set to 0.20% by mass or more, tapping that forms a hot metal stream that erodes the hearth of two or more tapholes that discharge hot metal This is a method for operating a blast furnace, characterized in that tapping from the mouth is restricted or stopped.

In the method for operating a blast furnace according to the present invention,
A tap hole that forms a flow of hot water that erodes the hearth is: (1) Among two or more tap holes that discharge hot metal, the rate of rise in the temperature of the hearth of the blast furnace during tapping differs from that of other tap holes. A tap hole that continuously exceeds the rate of temperature rise of the hearth of a blast furnace for at least 24 hours during tapping using a tap hole, or (2) a predetermined angle with each of two or more tap holes The powdery tracer is blown from each of the multiple tuyeres arranged in
The total amount (W) of metal blown from these tuyeres and the total amount (W ') of metal discharged from each of a plurality of tapholes within two hours after the end of the blowing, for each of two or more tapholes. The value (W '/ W) calculated for the tap hole is a small example.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a method for operating a blast furnace according to the present invention will be described in detail with reference to the accompanying drawings. In the following description of the embodiments, the same components as those indicated by the reference numerals used in FIG. 9 described above will be denoted by the same reference numerals, and redundant description will be omitted as appropriate.

In the present embodiment, for example, in the blast furnace 1 shown in FIG. 9, the separated molten iron slag is sequentially discharged from four tap holes 7a to 7d provided at intervals of 90 degrees with respect to the center of the basin 8. (2) charging the titanium source into the blast furnace 1 and (3) discharging from the tapholes 7a and 7b. (4) Tap holes 7a to 7
This is performed through a step of limiting or suspending the discharge from a specific tap hole of d. Hereinafter, each of these steps will be described in detail.

(1) Measurement of the temperature of the hearth 10 or the rate of rise of this temperature In the present embodiment, the hearth 10a constituting the hearth of the blast furnace 1
Using the thermometer attached to the refractory brick of each hearth side wall 10b, the temperature of the hearth portion 10 or the rate of increase of this temperature during the operation of the blast furnace 1 is obtained.

FIG. 1 is a plan view showing the arrangement of thermometers 15a to 15d provided on the furnace bottom 10a of the blast furnace 1 and thermometers 16a to 16h provided on the hearth side wall 10b in this embodiment. .

As shown in FIG. 1, in this embodiment, thermometers 15a to 15a are provided on refractory bricks of a furnace bottom 10a located immediately below tapholes 7a to 7d provided in a pool 8 of a blast furnace 1.
d, and at the 45-degree pitch on the refractory bricks of the hearth side wall 10b in accordance with the position immediately below the tap holes 7a to 7d,
Thermometers 16a to 16h are provided.

Each of the thermometers 15a to 15d and the thermometers 16a to 16h may be any well-known and commonly used thermometer which is installed on the refractory brick of the hearth 10 of the blast furnace 1 and may be a specific thermometer. It is not limited to the type.

The temperature of the refractory brick on the furnace bottom 10a is measured by thermometers 15a to 15d, and the thermometers 16a to 16h
Thereby, the temperature of the refractory brick on the hearth side wall 10b is measured.
From these measured values, the temperature of the refractory brick in the hearth 10 or the rate of increase in the temperature of the refractory brick in the hearth 10 is determined.

In the present embodiment, the temperature of the hearth 10 of the blast furnace 1 during operation or the rate of increase in this temperature is obtained in this manner. (2) Injection of Titanium Source into Blast Furnace 1 The present inventors set the hearth 10 in the blast furnace 1 shown in FIG.
The local wear of the refractory brick is based on the premise that the hot metal flow in the pool 8 is deeply involved, and is counterclockwise at a central angle from the tap hole (for example, the tap hole 7b) during tapping. To 4
A predetermined amount (Co mass conversion value: Wc) of a Co oxide was blown as a tracer together with hot air from the tuyere 6 located at 0.5 °, and the Co concentration contained in the hot metal discharged from the tap hole 7b to the outside of the furnace. By tracking the change over time, a test for determining the total amount Wc 'of Co in the hot metal discharged from the tap hole 7b within two hours after the end of the blowing was performed by using a test other than the tap hole 7b. The deviation in the circumferential direction of the molten metal flow in the hearth was measured by performing the same for all of the pig irons 7a, 7c and 7d. The reason for limiting the tracking time to 2 hours is that
This is because, if two hours have passed after the blowing, most of the Co blown from each of the tuyeres 7a to 7d is discharged outside the furnace. The measurement results are shown in a graph in FIG.
From the graph shown in FIG. 2, the phenomena listed below were confirmed.

(A) When the temperature of the furnace bottom 10a changes at a low value, each tap hole 7a with respect to the Co mass conversion value Wc
Value of the total amount Wc 'of Co in the hot metal discharged from
c '/ Wc) showed a value almost equal to 1 in each of the tap holes 7a to 7d.

(B) When the temperature of the furnace bottom 10a is increasing, the value (Wc '/ Wc) shows a small value in the range of 0.4 to 0.75. When the heat load of the furnace bottom 10a is increasing, the value (Wc '/ Wc) at each of the tap holes 7a to 7d is in the range of 0.4 to 0.75 for each of the tap holes 7a to 7d. Had significant deviations.

(C) When the heat load on the furnace bottom 10a rises,
In any part of the furnace bottom 10a, the temperature rising speed of the furnace bottom 10a changed in accordance with the tapping hole use timing. These phenomena (a) to (c) were evaluated using a mathematical model that simulates the hot metal flow at the bottom based on the material balance in the pool 8. As a result, the following was found.

As can be seen from the aforementioned report and the results of past blast furnace dismantling studies, the hearth section 10 of the blast furnace 1 has a low liquid permeability region mainly composed of molten iron slag, kish graphite and coke fine particles. .

FIG. 3 is a partial longitudinal sectional view showing a case where the low liquid permeability region 11 is formed so as to cover the entire furnace bottom 10a. FIG. FIG. 12 is a partial vertical cross-sectional view showing a case where a part has disappeared in FIG.

When the value (Wc '/ Wc) is close to 1, FIG.
As shown in FIG. 5, the low liquid permeability region 11 covers the entire furnace bottom 10a. In this case, the flow rate and the flow velocity of the hot metal flow 13a in the deep hearth 10c are both small.

On the other hand, as shown in FIG. 4, when the low-liquid-permeability region 11 has partially disappeared in the disappearance portion 12, the amount of molten iron discharged from the deep hearth 10c through the disappearance portion 12 is reduced. To increase. For this reason, in the hot metal discharged from each of the tap holes 7a to 7d, the discharge ratio of the hot metal containing Co blown from the tuyere 6 decreases, and the value (Wc '/ Wc) becomes 0.4 to 0.5. The flow rate and the flow velocity of the hot metal flow 14a in the deep hearth 10c are both increased and the heat load of the hearth 10 is increased.
Causes the refractory brick to wear.

FIG. 5 is an explanatory view showing an example of the pool 8 in which the low-liquid-permeability region 11 has partially disappeared in the disappearing portion 12. As shown in FIG. 5, depending on the positional relationship between the position where the vanishing portion 12 is formed and the tapholes 7a to 7d, the supply amount of the hot metal flow 14a from the deep hearth 10c varies. That is, in the example shown in FIG.
At 7b, the amount of hot metal discharged from the deep hearth 10c increases, thereby decreasing the value (Wc '/ Wc). On the other hand, at the tapholes 7c and 7d, the discharge amount of the hot metal from the deep furnace bottom 10c hardly increases, and the degree is extremely small, though affected. For this reason, the value (Wc '/ Wc) when tapping from each of the tapholes 7a and 7b is represented by the taphole 7c,
It becomes smaller than the value (Wc '/ Wc) when tapping from each of 7d, and a deviation occurs between the two. When the hot metal is discharged using the tapholes 7a and 7b with a large amount of hot metal discharged from the hearth deep part 10c, the flow velocity of the hot metal flow 14a in the hearth deep part 10c increases, and the hot metal flow is disposed in the hearth part 10. It appears as an increase in the indicated temperature of one of the thermometers 15a to 15d and the thermometers 16a to 16h. For this reason, when tapping is performed using tap holes 7a and 7b that generate a molten metal stream that erodes the refractory bricks constituting the hearth section 10, the thermometer 15
A certain correlation appears in which the indicated temperature of any one of a to 15d and 16a to 16h increases.

That is, when the temperature of the hearth section 10 is changing at a low value, the low liquid permeability area 11 covers the entire furnace bottom 10a, and the value is low at any of the tap holes 7a to 7d. (Wc '/ Wc) approaches 1. On the other hand, when the temperature of the hearth 10 is increasing, the vanishing part 12 is present in a part of the low liquid permeability area 11 and the values (Wc ′ / Wc) shows a low value. In particular, the values of tap holes 7a and 7b show even lower values, and there is a deviation in the value (Wc '/ Wc) depending on each of tap holes 7a to 7d.

Therefore, in the present embodiment, the thermometers 15a to 15a
When it is determined that the heat load of the hearth 10 is increasing due to any of the indicated temperatures 15d and 16a to 16h, the disappearance part 12 is formed in a part of the low liquid permeability area 11. Then, the flow rate and the flow rate of the hot metal flow 14 a from the deep hearth 10 c increase through the vanishing portion 12, and it is determined that the flow of the hot metal flow 14 a causes the temperature of the hearth 10 to rise. Then, a titanium source is introduced into the furnace from at least one of the furnace port 2 and the tuyere 6 of the blast furnace 1 for the purpose of forming titanium bare on the surfaces of the furnace bottom 10a and the hearth side wall 10b. After the titanium source is put into the furnace, tapping is performed from tapholes 7a and 7b that cause a flow of molten metal 14a that erodes the refractory bricks constituting the hearth portion 10, so that the hearth deep portions 10c and 10d are made of titanium. The hot metal having a high concentration is sufficiently replaced, and the titanium concentration of the hot metal discharged from the tap holes 7a and 7b increases. When the titanium concentration of the hot metal spouted from each of the tap holes 7a and 7b provided in the blast furnace 1 increases, the hot metal having a high titanium concentration prevails in the deep hearths 10c and 10d.

The means for charging the titanium source into the blast furnace 1 may be a well-known and conventional means, and is not limited to a specific means. In this embodiment, the titanium source is charged into the blast furnace 1 in this manner.

(3) Control of Titanium Concentration of Hot Metal Discharged from Tapholes 7a and 7b In the present embodiment, the control of the titanium concentration in the hot metal discharged from the tapholes 7a and 7b, which is measured by a well-known and conventional measuring device. A titanium source is charged into the blast furnace 1 until the titanium concentration becomes 0.2% or more.

Here, the reason why the titanium concentration in the hot metal is limited to 0.2% or more is that a titanium bear is reliably and easily formed on the surfaces of the hearth 10a and the hearth side wall 10b constituting the hearth 10. To do that.

FIG. 6 is a graph showing an example of the relationship between the Ti content in the hot metal and the viscosity of the hot metal. As shown in the graph of FIG. 6, when titanium and a compound of titanium are contained in the hot metal in an amount of 0.2% or more, the viscosity of the hot metal sharply increases. For this reason, it is easy to generate titanium bare on the surfaces of the hearth 10a and the hearth side wall 10b.

In this embodiment, the titanium concentration of the hot metal discharged from the tap holes 7a to 7d is controlled in this way. (4) Restriction or suspension of discharge from a specific tap hole among the tap holes 7a to 7d As described above, the hot metal flow 14 from the deep bottom 10c.
When the flow rate and the flow velocity of a increase, the indicated temperature of any one of the thermometers 15a to 15d and 16a to 16h disposed on the hearth 10 increases.

For this reason, the powdery tracer is blown from each of the four tuyeres 6 arranged at a predetermined angle with each of the tap holes 7a to 7d, and blown from each of the tuyeres 6 respectively. A value (W ′) calculated for each tap hole 7a to 7d based on the total amount W of the extracted metal and the total amount W ′ of the metal discharged from each of the tap holes 7a to 7d within two hours after the end of the blowing. / W) is the small tap hole in the hearth 1
It is determined that the tap hole is a tap hole that forms a hot water stream that erodes 0. In the following description, this value (W '/ W) is taken as an example where the tap hole is the tap hole 7b.

In the present embodiment, the value of the indicated temperature of any one of the thermometers 15a to 15d and 16a to 16h disposed on the hearth 10 is determined when tapping using the tap hole 7b. The rate at which the temperature of the hearth 10 rises depends on the other tap holes 7a,
Even when a period during which the temperature of the hearth 10 exceeds the temperature rising rate during tapping using 7c and 7d continues for a certain period of time, the tapping hole 7b prevents the flow of hot water eroding the hearth 10 from flowing. It is determined that the tap hole is to be formed.

Here, the duration of this period is slightly affected by changes in the operating state of the blast furnace 1,
From the viewpoint of the renewal speed of the core in the furnace bottom 10a, it is unlikely that the low liquid permeability region 11 is generated or disappears in a short time. It can be determined that a hot-water stream that erodes is formed.

Therefore, in this embodiment, the tap hole 7b
The rate of rise in temperature of the hearth 10 during tapping using
When the temperature rise rate of the hearth 10 in tapping using the other tapholes 7a, 7c, and 7d continuously exceeds 24 hours or more, the taphole 7b It is determined that the tap hole forms a eroding hot water stream.

The tapping from tap hole 7b, which is determined to be a tap hole that forms a flow of molten metal that erodes hearth section 10, is restricted or stopped, so that the hearth in deep hearth section 10c is removed. Both the flow rate and the flow velocity of the hot metal stream 14a are reduced to eliminate the flow of the molten metal that erodes the hearth section 10, whereby the titanium bear is securely placed on the surfaces of the hearth bottom 10a and the hearth side wall 10b constituting the hearth section 10. And easily generated.

In this case, the tapping from taphole 7b may be completely stopped, or may be limited to a certain amount or less. When restricting the tapping rate, it is preferable to limit the tapping rate to 75% or less of the tapping rate from the taphole in normal operation in order to eliminate the flow of hot water that erodes the hearth section 10 and to limit the tapping rate to a small value. The more you do, the better.

In this embodiment, all tap holes 7a to 7a
d will temporarily reduce the total emission capacity,
Since the fluidity of the hot metal is reduced by increasing the amount of titanium contained in the hot metal to 0.2% or more, the furnace floor 10 is slightly affected by the titanium concentration in the hot metal and the furnace heat level. Titanium bare can be reliably and easily generated on the surfaces of the furnace bottom 10a and the hearth side wall 10b.

As described above, according to the present embodiment, the titanium concentration in the pig is increased by charging the titanium source into the furnace, and at the same time, the tap hole with a large supply of hot metal from the deep part of the furnace bottom is used. After the hot metal having a high titanium concentration has sufficiently reached the deep furnace bottom, the flow rate and flow velocity of the hot metal flow 14a in the deep furnace hearth 10c are all moderated by restricting or stopping the use of the tap hole. Accordingly, hot metal of high titanium can be spread over the surfaces of the hearth 10 a and the hearth side wall 10 b constituting the hearth 10, and the surfaces of the hearth 10 a and the hearth side wall 10 b constituting the hearth 10 are formed. Thus, a titanium bear can be reliably and easily produced.

For this reason, while continuing the operation of the blast furnace, the titanium bare is effectively removed from the furnace bottom 10a or the hearth side wall 10b.
Thus, it is possible to effectively prevent the erosion of the refractory brick due to the generation of the titanium bear by charging as little titanium source as possible.

Therefore, according to the present embodiment, the operating life of the blast furnace can be extended, and the cost of the iron making process can be significantly reduced.

[0049]

EXAMPLES The present invention will be described more specifically with reference to examples. (Example 1) In this example, an operation test was performed using the blast furnace 1 shown in FIGS. 1 and 9 in which the diameter of the furnace bottom 10a was 15 m.

During operation of the blast furnace 1 in this operation test,
The local temperature rise was measured at this site by the thermometer 16h in FIG. Tap holes used at the time of this measurement were tap holes 7b and 7c. Also, in FIG.
The tapping and closing timing and the indicated value of the thermometer 16h are collectively shown in a graph.

Therefore, in the present embodiment, in the continuous tapping, four tapping counterclockwise from the tap holes 7a to 7d at the central angle.
From the tuyere 6 provided at the position of 0.5 degrees, a tracer made of Co oxide is approximately 30 kg (22 k in metal Co conversion).
g) is blown, and the hot metal spouted from each of the tap holes 7a to 7d is sampled every 5 minutes until the hot metal is clogged, and C in the hot metal is sampled.
o concentration was analyzed by atomic emission method, and each tap hole 7a-7
d, the weight of Co discharged from each of the tap holes 7a to 7 is measured.
The value (W '/ W) was determined for each d. The results are summarized in Table 1.

[0052]

[Table 1] From Table 1, tap holes 7b and 7c have values (Wc '/
Wc) is less than 0.75, the heat load of the hearth 10 is high, and it is estimated that the defect 12 is generated in a part of the low permeability region 11 covering the hearth 10a. Is done. Above all, since the value of the tap hole 7c (Wc '/ Wc)) is particularly low, by tapping from the tap hole 7c, a larger amount of molten iron bottom flow 14a is supplied from the deep hearth 10c. it is conceivable that.

In this embodiment, as shown in the graph of FIG. 7, a titanium source is charged from the furnace port 2 and each of the tap holes 7b,
Although the concentration of titanium in the hot metal discharged from 7c was increased to more than 0.2% by mass, the increase in the indicated value of the thermometer 16h did not stop. Therefore, the tapping time of the taphole 7c was limited such that the tapping amount from the taphole 7c was 60% of the normal operation state.

As a result, shortly thereafter, the thermometer 16
The increase in the indicated value of h was eliminated, and the temperature rapidly decreased.
Then, after the charging of the titanium source from the furnace port 2 is stopped and the indicated value of the thermometer 16h falls below a certain level, the tap hole 7
Although the tapping restriction of c was released, the indicated value of the thermometer 16h did not increase. This is considered to be because titanium bears were sufficiently formed on the surface of the refractory brick constituting the hearth portion 10, and this portion was protected from the hot metal flow 14a from the hearth deep portion 10c.

(Example 2) In the same blast furnace as in Example 1, an increase in the indicated value of the thermometer 15c was measured at another time. At this measurement time, tapping was performed using tap holes 7b and 7c. Thus, the tracer was blown in the same manner as in Example 1. The results are summarized in Table 2.

[0056]

[Table 2] During this operation, by comparing the temperature rise rate of the thermometer 15c with the tapping timing, the period in which the temperature rise rate at the time of tapping by the taphole 7c exceeds the temperature rise rate at the time of tapping by the taphole 7d. According to the result of the value of the tracer injection (Wc '/ Wc) that has been continued for 24 hours or more,
c was identified as a taphole forming a hot water stream that erodes the refractory bricks of the hearth 10.

Therefore, in this embodiment, after the indicated value of the thermometer 15c reaches the reference value, a titanium source is charged from the furnace port 2 and the titanium of the hot metal discharged from each of the tap holes 7a to 7d. Although the concentration was increased to more than 0.2%, tapping at taphole 7c was not restricted in order to repair tapping gutters at other tapholes. Then, the indicated value of the thermometer 15c continued to increase.

Therefore, in the present embodiment, the use of the tap hole 7c is stopped and the use of the tap hole 7a is started. This allows
Shortly thereafter, the increase in the indicated value of the thermometer 15c was eliminated, and the temperature rapidly decreased.

Then, after the charging of the titanium source from the furnace port 2 was stopped and the indicated value of the thermometer 15c fell below a certain level, the tapping restriction of the tap hole 7c was released.
Did not increase. This is the hearth 10
Is sufficiently formed on the surface of the refractory brick constituting the furnace, and this portion is formed by the molten iron flow 14a from the hearth deep portion 10c.
Probably because they were protected from.

(Example 3) In the same blast furnace as in Example 1, an increase in the indicated value of the thermometer 16f was measured at another time. At this measurement time, tapping was performed using tap holes 7b and 7c. In addition, FIG. 8 collectively shows the tapping and closing timing and the indicated value of the thermometer 16f in a graph.

As shown in the graph of FIG.
In this embodiment, it is estimated that the tap hole 7b is a tap hole causing a molten metal flow that erodes the refractory bricks of the hearth 10 by comparing the rise in the indicated value of the indicated value and the tapping timing. Was.

In this embodiment, after the indicated value of the thermometer 16f reaches the reference value without introducing the tracer, a titanium source is charged from the furnace port 2 and discharged from the tap holes 7b and 7c. By limiting the tapping time of tap hole 7b after the titanium concentration of the hot metal exceeds 0.2%, the tapping amount was set to 75% of the normal operation state.

As a result, shortly thereafter, the thermometer 16
The temperature rise of the indicated value of f was eliminated, and the temperature rapidly dropped. Then, after the charging of the titanium source from the furnace port 2 was stopped and the indicated value of the thermometer 16f became a certain level or less, the tapping restriction of the tap hole 7b was released, but the indicated value of the thermometer 16f was released. The rise did not occur. This is considered to be because titanium bears were sufficiently formed on the surface of the refractory brick constituting the hearth portion 10, and this portion was protected from the hot metal flow 14a from the hearth deep portion 10c.

In Examples 1 to 3, the tap hole 7 was used.
Tapping was performed from two tapholes 7b and 7c among the tapholes a to 7d, and the other tapholes 7a and 7d were stopped for, for example, hot metal gutter repair. However, the present invention is not limited to a case where tapping is performed from two tap holes, and is similarly applied to a case where tapping is performed from three or more tap holes.

[0065]

As described above in detail, according to the present invention, while maintaining the operation of the blast furnace, the titanium bear having the brick protecting effect can be effectively removed from the hearth, that is, the refractory bricks of the hearth and the hearth side wall. By generating on the surface of the blast furnace, it is possible to prevent the erosion of the refractory brick by charging a small amount of titanium source without being affected by the repair work of the hot metal gutter, thereby extending the operating life of the blast furnace, The cost of the iron making process can be reduced.

The significance of the present invention having such an effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 is a plan view showing the arrangement of a thermometer provided on a furnace bottom of a blast furnace and a thermometer provided on a hearth side wall in the embodiment.

FIG. 2 is a graph collectively showing the results of measuring the temporal change in the Co concentration contained in the hot metal discharged from a tap hole after blowing a Co oxide as a tracer from a tuyere.

FIG. 3 is a partial longitudinal sectional view showing a case where a low liquid permeability region is formed so as to cover the entire furnace bottom.

FIG. 4 is a partial vertical cross-sectional view showing a case where a low liquid permeability region has partially disappeared in a disappearing portion.

FIG. 5 is an explanatory view showing an example of a pool of water in which a low liquid permeability region has partially disappeared in a disappearing portion.

FIG. 6 is a graph showing an example of the relationship between the Ti content in the hot metal and the viscosity of the hot metal.

FIG. 7 is a graph showing the results of Example 1.

FIG. 8 is a graph showing the results of Example 2.

FIG. 9 is a perspective view schematically and simplified showing an example of a blast furnace which is a large reactor in the iron making process, with a part thereof broken.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Furnace 3 Furnace 4 Furnace belly 5 Morning glory 6 Tuyere 7a-7d Taphole 8 Hot water pool 9a Furnace upper part 9b Furnace lower part 10 Furnace bottom 10a Furnace bottom 10b Furnace floor side wall

Claims (3)

[Claims] When a blast furnace is operated by sequentially discharging hot metal from at least two or more tap holes provided in a blast furnace, the temperature of the hearth of the blast furnace or After the temperature rise rate is equal to or higher than the predetermined critical value, from the tap hole that has discharged the hot metal when the temperature has exceeded the critical value by charging the titanium source into the furnace of the blast furnace. The concentration of titanium in the hot metal to be tapped is 0.20% by mass.
After the above, a method of operating a blast furnace, characterized by restricting or suspending tapping from a tapping hole that forms a flow of molten metal that erodes the hearth of the two or more tapping holes. 2. A tap hole that forms a flow of molten metal that erodes the hearth, wherein, among the two or more tap holes, the rising speed in tapping is a tap hole using another tap hole. The method for operating a blast furnace according to claim 1, wherein the tap hole is a tap hole that continuously exceeds the rising speed of the pig iron for 24 hours or more. 3. A taphole for forming a flow of molten metal that erodes the hearth, wherein a powdery tracer is formed from each of a plurality of tuyeres arranged at a predetermined angle with each of the two or more tapholes. And the total amount of metal (W ') discharged from each of the plurality of tap holes within two hours after the end of the blowing. The values (W '/
The method for operating a blast furnace according to claim 1, wherein W) is a small tap hole.