JP3061965B2 - Blast furnace operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently and stably operating a blast furnace by controlling the temperature of a heat storage zone in a blast furnace according to the reducibility of a sintered ore.

[0002]

2. Description of the Related Art In a blast furnace, an iron source mainly composed of sintered ore and lump ore (70% or more) and coke for ordinary metallurgy are charged in layers, and the iron source is reduced. It melts to a state and produces pig iron. At this time, in order to enhance the reduction efficiency of the iron source, as described in, for example, Japanese Patent Publication No. 52-43169, the iron source and small coke (average particle size of 20 m
m) is preliminarily mixed, and the small coke mixed iron source and the coke for ordinary metallurgy are charged in layers to improve air permeability in the furnace and improve reducibility.

[0003] The temperature of the heat preservation zone above the cohesive zone in a blast furnace using this normal metallurgical coke (JIS reactivity is about 20%) is about 1000 ° C. Is equal to the temperature at which the gasification reaction of C + CO ₂ = 2CO is started. On the other hand, the softening start temperature of the iron source is 110
When the softening starts, the permeability in the furnace deteriorates, and the permeation of the reducing gas becomes insufficient. For this reason,
When only metallurgical coke is used, heat storage zone temperature is 1
Since the temperature is as high as about 000 ° C., the CO generated in the gasification reaction cannot be effectively used, and the contact between the iron source and the reducing gas is uneven due to deterioration in air permeability due to softening of the iron source. As a result, the indirect reduction of the iron source in the heat storage zone cannot be effectively utilized, and it has been difficult to significantly improve the reduction efficiency even when the iron source and the small coke are mixed as described above.

In order to improve this, Japanese Patent Application Laid-Open No. 1-3617 has been disclosed.
As proposed in Japanese Patent Publication No. 0, a highly reactive coke of 25 mm or less is replaced with a part of a normal metallurgical coke, and the replaced highly reactive coke is mixed with an iron source or a normal metallurgical coke and mounted in a blast furnace. There is something to enter. This highly reactive coke is produced by partially blending highly reactive non-coking coal into the metallurgical coke making coal, or by mixing limestone or alkali as a reaction promoting catalyst into the metallurgical coke making coal. It is. The JIS reactivity is adjusted by adjusting the amounts of the slightly non-coking coal, limestone and alkalis.

[0005] This highly reactive coke usually has higher reactivity than coke for metallurgy and has a relatively small particle size, so that CO ₂ in the furnace comes into contact with the surface of the highly reactive coke and C + CO ₂ = 2CO The gasification reaction is carried out more actively from a lower temperature. As a result, the CO gas generated in the furnace effectively reacts with the iron source to promote the reduction reaction of the iron source. The above C +
The gasification reaction of CO ₂ = 2CO is an endothermic reaction (−38.8 k
cal / mol), it is possible to lower the temperature of the heat preservation zone formed in the massive band portion in the blast furnace.
This increases the temperature difference between the iron source and the softening temperature,
Since the air permeability does not deteriorate, the generated C
The contact between O and the iron source becomes uniform, the reduction efficiency is improved, and the coke ratio can be reduced.

[0006]

However, the sintered ore as the iron source cannot always be produced from a constant raw material.
The quality changes depending on the raw material circumstances at that time.
For example, when the components of the raw materials to be blended, particularly Al ₂ O ₃ , change, the reducibility of the sinter changes due to the change.
For example, as Al ₂ O ₃ increases, the reducibility tends to deteriorate, and conversely, as Al ₂ O ₃ decreases, the reducibility tends to improve. When the reducibility of the sinter changes, if the temperature of the heat storage zone is kept constant, the reduction reaction efficiency changes and the furnace condition becomes unstable, and the fuel ratio accordingly increases. Has the problem of rising. Further, the temperature of the heat preservation zone which can be reduced by high-reactivity coke was about 900 ° C., which was not sufficient.

The present invention makes it possible to lower the temperature of the heat storage zone to about 750 ° C., and to control the temperature of the heat storage zone according to the reducibility of the sinter to reduce the reduction reaction of the entire furnace. It is an object of the present invention to promote stable operation at a low fuel ratio under high reaction efficiency.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and includes a sintered ore, an iron ore mainly composed of lump ore having a crystallization water of 3% or more, a coke for ordinary metallurgy and JIS reactivity is 30% or more and average particle size is 25mm
In the blast furnace operating method of operating by charging the following highly reactive coke, in accordance with the reducibility of the sinter, the usage ratio of the highly reactive coke, JIS reactivity, particle size or
Is the usage ratio of the lump iron ore, and at least 1
The temperature of the heat preservation zone in the blast furnace is controlled by adjusting the temperature.

[0009]

The highly reactive coke used in the present invention has a JIS reactivity of 30% or more (measured by the reactivity test method of JIS K2151-1977) and an average particle size of 25 m.
m or less is required. This is disclosed in Japanese Patent Application Laid-Open No. 1-36.
As disclosed in Japanese Patent Publication No. 710, when the JIS reactivity is less than 30% or the average particle size exceeds 25 mm, the effect of lowering the heat storage zone temperature is not observed.

Since the heat storage zone temperature which can be lowered by this highly reactive coke is at most 900 ° C., the present inventors conducted various experiments and studies to further lower the heat storage zone temperature. In addition, it has been found that by charging lump ore containing 3% or more of crystallization water, it is possible to reduce the heat storage zone temperature to about 750 ° C. The reason why the crystallization water content of lump iron ore is set to 3% or more is that the amount of lump iron ore that can be charged into a blast furnace is at most about 30% by weight of the entire iron source. If it is less than the above, the effect of lowering the heat storage zone temperature will be small.

Next, a method for controlling the temperature of the heat preservation zone will be described. As a method of measuring the heat storage zone temperature,
A method of measuring by inserting a sonde from the blast furnace wall is generally used, but the method is not limited to this. Fig. 1 shows the relationship between the average particle size of the highly reactive coke, the JIS reactivity, the increase in the usage ratio (usually the usage ratio with coke for metallurgy), and the decrease in the heat storage zone temperature. As you can see,
As the use ratio of the highly reactive coke is increased, the grain size is reduced, or the JIS reactivity is improved, the temperature reduction range of the heat storage zone increases. In other words, by adjusting the use ratio, particle size, and JIS reactivity of the highly reactive coke,
It turns out that it is possible to control the heat storage zone temperature.

FIG. 2 shows a lump containing 3% or more of water of crystallization when operating a blast furnace by replacing 20% by weight of normal metallurgical coke with highly reactive coke having a JIS reactivity of 70 and an average particle size of 10 mm. This graph shows the relationship between the increase in the use ratio of iron ore, the amount of water of crystallization contained, and the decrease in the heat storage zone temperature. As can be seen from the figure, when the amount of lump ore used increases, the decrease in the heat storage zone temperature increases, and when lump ore containing a large amount of water of crystallization is used, the decrease in the heat storage zone temperature increases as described above. In other words, it is possible to control the heat storage zone temperature by adjusting the amount of lump ore used and using lump ore having different amounts of water of crystallization.

Further, the reducibility of the sintered ore (hereinafter simply referred to as JI
(Referred to as S-RI) and the heat storage zone temperature will be described. FIG. 3 shows the relationship between the JIS-RI of the sintered ore and the reduction reaction efficiency when the heat storage zone temperature is 1000 ° C. From this figure, it can be seen that when the JIS-RI of the sinter decreases, the reduction reaction efficiency sharply decreases.

On the other hand, it is desirable to lower the temperature of the heat preservation zone as much as possible in order to improve the reduction reaction efficiency. The low-temperature reducibility of the sintered ore up to is important. Therefore, in order to determine the appropriate heat preservation zone temperature for each of the sinters having JIS-RI of 55% and 62%,
The test was performed using a blast furnace reaction simulator proposed in Japanese Patent No. 27038. This fills the porous lump ore from the upper part and conducts the reducing gas from the lower part to surround the furnace core tube and a part of the furnace core tube in countercurrent contact between the reducing gas and the porous lump ore. And a heater movably provided in the downstream direction of the reducing gas.

As a result, as shown in FIG. 4, the temperature of the thermal storage zone having the highest reaction efficiency is 880 ° C. in the case of a sintered ore having a JIS-RI of 62%, while the temperature of the sinter having a JIS-RI of 55% is 880 ° C. It was 930 ° C. in the case of consolidation. Figure 5 shows the sinter JI
It is an investigation of the relationship between S-RI and the appropriate heat storage zone temperature at which the reaction efficiency is the best. As can be seen from this figure, the appropriate heat storage zone temperature decreases as the JIS-RI of the sintered ore increases. In this case, the width of the decrease is slightly different depending on the total porosity ε of the sintered ore.

As described above, according to the present invention, the proportion of the highly reactive coke charged into the furnace according to the reducibility of the sintered ore, the particle size, the JIS reactivity, and the proportion of the crystallized water lump iron ore are used. By controlling at least one of lump iron ores of different brands containing water of crystallization to control the temperature of a heat preservation zone formed above a cohesive zone in a furnace to an appropriate value capable of enjoying the maximum reduction reaction efficiency. However, when the control range of the heat storage zone temperature is small, the use ratio, particle size, and JIS of the highly reactive coke
Reactivity, the use ratio of the crystallized water lump ore, adjust any one of the lump ore adjusting means of different brands of the contained crystallization water alone, and when the control width is large, combine the adjusting means It is preferable to make a plurality of adjustments.

[0017] Further, since the crystallized water lump iron ore undergoes thermal destruction in the furnace and the air permeability in the furnace tends to fluctuate, first, the temperature of the heat preservation zone is controlled by high-reactivity coke, and the shortage is added to the crystallized water. It is preferable to control with lump ore. In this case, adjusting the usage ratio of the highly reactive coke has the greatest control width of the heat storage zone temperature as compared with adjusting the particle size and the JIS reactivity, but this adjustment usually involves coke for metallurgy. Alternatively, it is necessary to adjust the amount of sintered ore, which is complicated. On the other hand, it is preferable to adjust the particle size of the highly reactive coke without accompanying the above-described complication, but if the particle size is too small, the yield is deteriorated due to scattering with the blast furnace gas, or in the furnace mass part, This may cause clogging and deteriorate air permeability. Further, if the JIS reactivity of the highly reactive coke is adjusted, the permeability in the furnace does not change, and it is usually unnecessary to adjust the amount of coke or sinter for metallurgy. Has the skill to build highly reactive coke.

In the case of water-containing lump iron ore, lump ore having a high content of water of crystallization is preferable because the heat storage zone temperature can be greatly reduced. May worsen sex. On the other hand, it is preferable to adjust the usage ratio of lump iron ore since the permeability in the furnace is not largely changed, but the temperature control width of the heat preservation zone is small. As described above, since each adjusting means has its advantages and disadvantages, it is necessary to use the adjusting means properly according to the operating state of the blast furnace at each time.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below. Table 1 shows an example in which a blast furnace was operated using highly reactive coke and crystallized water lump iron ore, and controlling the heat storage zone temperature in accordance with JIS-RI of the sintered ore. Here, lump A ore is lump ore containing 8.1% of water of crystallization and is lobe river ore.
Lump ore B is lump ore containing 3% of water of crystallization and is gore ore.

[0020]

[Table 1]

The target blast furnace is a medium-sized blast furnace having an inner volume of 3000 m ³ , the O / C (ore amount / coke amount) of the charged material is 4.2, and an iron source mainly composed of sintered ore and lump iron ore. (Consisting of sintered ore, lump iron ore, pellets, excellent lump ore (Hamasley ore, Newman ore, etc.)) and coke for ordinary metallurgy (JIS reactivity 20%, average particle size 50 mm) are charged in layers. In addition, the temperature of the tuyere front frame is 2180 ° C.
(Hot air temperature 1200 ° C, blast moisture 25g / Nm ³ -ai
r, oxygen enrichment amount 0.013 Nm ³ / Nm ³ -air, pulverized coal injection amount 100 g / Nm ³ -air).

Example 1 has a JIS reactivity of 70% and a particle size of 5
In a state where 20% of highly reactive coke of 10 to 10 mm is mixed with ordinary metallurgical coke and operated (the heat storage zone temperature in this state is 890 ° C), the JIS-
This is the case where RI changes from 60% to 62%. When the JIS-RI of this sinter increases, even if the heat storage zone temperature indicating the optimal reduction reaction and reduction efficiency of the sinter moves to a lower temperature side,
As a result of the operation as it was, the furnace condition became unstable (before adjustment), and thus, as shown after the adjustment, the use ratio of lump iron ore A was increased to control the heat storage zone temperature.

This is because the JIS-RI of the sintered ore is 62
5 is 880 ° C. from FIG. 5, the optimal heat storage zone temperature is 10 ° C. (890 ° C.-88 ° C.).
0 ° C). Based on this, the use ratio increase of lump iron ore A is calculated according to FIG. 2 to be 5%. For this reason, the use ratio of lump iron ore A was set to 18% (13% + 5%),
The excellent lump iron ore was reduced by 5% to 2%. As a result, the operation was performed while controlling the temperature of the heat preservation zone to 880 ° C. as calculated above, and as a result, the reactor condition was stabilized and the fuel ratio was 484 kg / t-.
pig.

In Example 2, the JIS-RI of the sintered ore was 55%.
Operating without controlling the heat storage zone temperature, the furnace condition became unstable and the fuel ratio was 4%.
Since it increased to 84 kg / t-pig (before adjustment), this is an example in which the fuel ratio is reduced by adjusting the usage ratio of the highly reactive coke as shown after the adjustment.
-The optimal thermal storage zone temperature before the change of RI is 920 ° C from FIG.
The optimum thermal storage zone temperature after the change is 850 ° C.

Due to the change in JIS-RI of the sintered ore, the optimum heat storage zone temperature is reduced by 70 ° C., and the highly reactive coke used has a JIS reactivity of 70% and a particle size of 5 to 10 mm.
Therefore, the increase in the use ratio of the highly reactive coke is calculated from FIG. 1 to be 15%. For this reason, the usage ratio of highly reactive coke is 25% of that of ordinary metallurgical coke.
This is an example in which the fuel ratio was greatly reduced to 473 kg / t-pig as a result of adjusting the temperature to (10% + 15%) and controlling and maintaining the heat storage zone temperature at 920 ° C., which is the optimum heat storage zone temperature. .

In Example 3, the JIS-RI of the sintered ore was 62%.
JIS of high reactivity coke when it changes from 55% to 55%
This is an example in which the heat preservation zone temperature is controlled by using different reactivities.

In Example 4, the JIS-RI of the sintered ore was 62%.
In this example, the particle size of the highly reactive coke was adjusted to control the temperature of the heat preservation zone when the temperature changed from 65% to 65%.

In Example 5, the JIS-RI of the sintered ore was 60%.
This is an example in which the heat storage zone temperature is controlled by changing the brand of the crystal-containing water lump ore when changing from lump to 63%.

In Example 6, the JIS-RI of the sintered ore was 52%.
JIS of highly reactive coke when it changes from 75% to 75%
This is an example in which the thermal preservation zone temperature is controlled by adjusting all of the reactivity, particle size, use ratio, brand of crystal-containing water lump iron ore, and use ratio. In addition, it is preferable to use a raw material containing CaCO ₃ , for example, a non-calcined agglomerate, because the thermal endothermic reaction of CaCO _{3 in} the furnace can further lower the heat storage zone temperature.

[0030]

As described above, according to the present invention, even if the reducibility of the sintered ore fluctuates, the JIS reactivity, particle size, usage ratio, and lump iron ore of the highly reactive coke are correspondingly changed. By controlling the contained water of crystallization and the usage ratio to an appropriate heat storage zone temperature, it is possible to operate the blast furnace efficiently with a stable furnace condition and a reduced fuel ratio, and the effect in this field is enormous. Things.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the JIS reactivity of highly reactive coke, the increase in the usage ratio by particle size, and the decrease in the heat storage zone temperature.

FIG. 2 is a graph showing the relationship between the increase in the usage ratio for each of the iron ore blocks A and B and the decrease in the heat storage zone temperature.

FIG. 3 is a graph showing the reduction reaction efficiency when the JIS-RI (reducible index) of the sinter changes when the heat storage zone temperature is 1000 ° C.

FIG. 4 is a graph showing the relationship between the reaction efficiency and the heat storage zone temperature when the JIS-RI of the sintered ore is 55% or 62%.

FIG. 5 is a graph showing a relationship between JIS-RI of a sintered ore and an optimum heat storage zone temperature.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Kuniyoshi Anan, Oita, Oita, Oita, 1st section, Nishinoshima, Nippon Steel Corporation Oita Works (56) References JP-A-2-200711 (JP, A) JP Hei 2-200712 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C21B 5/00

Claims (1)

(57) [Claims] 1. Sinter ore, iron ore mainly composed of lump ore having 3% or more of water of crystallization, usually coke for metallurgy and JI
In a blast furnace operating method in which a highly reactive coke having an S reactivity of 30% or more and an average particle diameter of 25 mm or less is charged, the blast furnace is operated in accordance with the reducibility of the sinter. A method for operating a blast furnace, comprising controlling at least one of a usage ratio, JIS reactivity, a particle size or a usage ratio of the lump ore, and a contained crystal water to control a heat preservation zone temperature in a blast furnace.