JPH1143709A - Operating method of hard furnace using sintered ore with good high temperature properties - Google Patents

Abstract

(57) Abstract: The present invention adjusts the pore size distribution of a sintered ore charged from the furnace top of a rigid furnace such as a blast furnace so that the high-temperature properties of the sintered ore become good. SOLUTION: The pore diameter distribution of the sinter is measured by a mercury intrusion porosimeter, and the sintering operation or the sinter is performed so that the average diameter of the open pores of 300 μm or less is in the range of 0.05 to 0.15 μm. Adjust the ingredients. [Effect] The blast furnace using the sinter of the present invention has improved air permeability, can stably maintain the operation of the blast furnace, achieve an increase in pulverized coal injection, an improvement in productivity, and a decrease in fuel ratio. can do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the operation of a solid-state furnace in which high-temperature properties of a sintered ore charged from the furnace top of a blast furnace or the like are maintained and a large amount of pulverized coal is injected. The present invention relates to a method of operating a solid furnace for the purpose of maintaining a stable state.

[0002]

2. Description of the Related Art In the operation of a solid furnace such as a blast furnace, it is necessary to maintain the high-temperature properties of the sintered ore charged from the furnace top in order to stably maintain the operation. In particular, it is indispensable to stably maintain high-load operation such as pulverized coal injection. For this reason, in iron and steel magazine (1980, P18
50), in the Iron and Steel Institute Lecture Meeting Magazine (1983, S75
As disclosed in 5), the sinter is charged into a crucible, the crucible is placed in an electric furnace, and a reducing gas is introduced from below the electric furnace to reduce the heat reduction of the sinter. A measuring method for measuring high-temperature properties such as a reduction ratio, a softening shrinkage ratio, and a pressure loss in a layer at a temperature from ordinary temperature to around 1500 ° C. is performed.

[0003]

By the way, a sintered ore having good high-temperature properties is evaluated based on data of a conventionally used high-temperature property measuring method, and a sintered ore having good high-temperature properties is produced based on the evaluation. The technology has not yet been established on the actual machine, only measuring the high-temperature properties of the sintered ore produced on the actual machine. The reason is that the accuracy of these measurement methods is not so good, and it cannot be said that the high-temperature properties of the sinter in the actual blast furnace are faithfully reproduced. The conventional measurement method is a measurement method using one electric furnace, in which a reducing gas is introduced from a reducing gas inlet below the electric furnace, and a thermometer installed in the electric furnace is heated according to a preset heating program. In this method, the sintered ore in the crucible disposed in the electric furnace is heated and reduced, so that the sintered ore is softened and melted, and the molten FeO is reduced (endothermic reaction), and the temperature of the sintered ore decreases. However, since the temperature of the electric furnace is raised according to the temperature raising program, heat is forcibly applied to the sintered ore, and the heat reduction proceeds.

[0004] In the actual furnace, when the sinter softens and melts and the molten FeO is reduced (endothermic reaction), and the temperature of the sinter decreases, unlike the above measurement method, the iron ore is forcibly forced. Since no heat is given, a reduction in the temperature of the molten FeO due to a decrease in the temperature, a deterioration in the fluidity of the molten material due to the temperature decrease, and a reduction in the reduction due to the reduction occur, and the heat reduction is delayed. As described above, the conventional measurement method is different from the phenomenon occurring in the actual furnace.Therefore, there should be a difference in the high-temperature properties of the sinter in the actual furnace. There was no difference, and it was impossible to produce sinter to maintain stable operation using the measurement results.

Accordingly, the present invention is intended to measure phenomena at the time of heat reduction of sinter occurring in an actual furnace, in particular, the rate of temperature rise, reduction rate, pressure loss of a bed, etc. By improving the measurement method so that the difference in the high-temperature properties of the generated sinter can also be detected by the measurement method, the results are used to produce sinter with good high-temperature properties and to operate the actual furnace. The purpose is to stably maintain.

[0006]

SUMMARY OF THE INVENTION In order to achieve the object, the method of the present invention for operating a rigid furnace using a sintered ore having good high-temperature properties has an average diameter of open pores of 300 μm or less.
It is characterized in that a sintered ore having a good high-temperature property of about 0.15 μm is charged from the top of a hard furnace. In addition, in a method of operating a hard furnace in which pulverized coal is blown at a rate of 150 kg / t or more from a tuyere of a blast furnace, a sintered ore having good high-temperature properties having an average diameter of open pores of 300 µm or less of 0.05 to 0.15 µm Is charged from the top of the rigid furnace.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to develop a method for producing the above-mentioned sintered ore, the present inventors have disclosed Japanese Patent Application Laid-Open No. 7-27623.
As disclosed in Japanese Unexamined Patent Publication, the number of electric furnaces is set to two, heating is performed in one electric furnace, and temperature control is performed in the other electric furnace. By using the same method as above, a measuring device and a measuring method that can measure the phenomenon of heat reduction occurring in the actual furnace were developed. That is, the electric furnace is arranged in upper and lower two stages, the joint of the electric furnace is connected by a flange, a reducing gas is introduced from below the lower electric furnace, and the lower electric furnace is heated as an empty tower, A crucible charged with sinter is placed in the upper electric furnace,
The temperature of the upper electric furnace and the temperature of the sintered ore in the crucible are simultaneously measured, and the electric power of the upper electric furnace is adjusted so that the difference between the temperatures becomes a predetermined constant value.

According to the measuring method using the above-described measuring device, the measured data shown in FIG. 1 is obtained. The horizontal axis in FIG. 1 shows the elapsed time of the experiment (minutes), the left vertical axis shows the reduction rate (%) of the sinter, and the right vertical axis shows the pressure loss (mmH ₂ O) of the packed bed of the sinter.
Is shown. Time 1 as an index for evaluating the high-temperature properties of the sintered ore - in pressure loss curve, pressure loss 200 mm ₂ O
The area of the above portion (the hatched portion in FIG. 1) was calculated, and this was named as S value. Then, the present inventors measured sinter ore manufactured by various actual machines by the measuring method using the above-described measuring device, and found that this S value governed the gas permeability in the lower part of the blast furnace. It is shown in FIG. The horizontal axis in FIG. 2 shows the S value, and the vertical axis shows the lower K value, which is an index of the lower air permeability of the blast furnace. The lower the S value, the lower the lower K value and the operation of the blast furnace is stable. .

Next, the present inventors investigated the properties of sintered ores produced by various actual machines, and found that the S value was determined by the average diameter (MS) of open pores of 300 μm or less in the sintered ores. Was found. It is shown in FIG. The horizontal axis in FIG.
S is shown and the vertical axis shows the S value. It can be seen that the lower the MS, the lower the S value. The MS was determined by measuring the pore size distribution in the sintered ore using a mercury intrusion porosimeter. According to this method, 4 to 5 g of a sintered ore crushed to a size of 2 to 3 mm is sampled, charged in a press-fitting sealed container, and mercury is pressed into the sealed container and the pressure is gradually increased. . The open pore diameter at which mercury can enter, corresponding to a certain injection pressure, is known from the device characteristics, and the amount of pores corresponding to the open pore diameter is determined from the volume of the injected mercury. The maximum mercury intrusion pressure is 33000 Psi, and the maximum open pore diameter into which mercury can enter is 300 μm. From the total data of the open pore diameter and the pore volume, the average diameter of the open pores of 300 μm or less can be calculated. Therefore, the numerical limit of 300 μm is the limit at which a mercury intrusion porosimeter can be measured.

A low S value indicates that the porosity of the fused layer formed of the sintered ore is small, and even if the pressure loss of the packed bed of the sintered ore shown in FIG. And the delay of reduction does not occur. The small average diameter (MS) of the open pores of 300 μm or less indicates that the specific surface area in contact with the reducing gas in the sinter is large, and the reduction is easily promoted. And when MS is small, 300μ
Although the amount of pores below m tends to decrease, the number of pores is maintained and the reduced metallic iron is present in a fine state, so that the shrinkage of the sintered ore layer is suppressed and the permeation of the reducing gas is secured. For this reason, reduction of the sintered ore is promoted, and the amount of the generated melt is small, and the permeability of the fusion layer is ensured.

The reason why the average diameter (MS) of the open pores is limited to 300 μm or less is that, as shown in FIG. 2, when the S value increases and exceeds 11, the lower K value of the blast furnace increases and the stable operation is maintained. As shown in FIG. 3, since the S value = 11 corresponds to the MS = 0.15 μm, the MS becomes 0.1.
It is preferably 15 μm or less, and if it is less than 0.05 μm, it is not economical with the current sinter production technology.

Next, a method for producing a sintered ore so that the MS is in the range of 0.05 to 0.15 μm will be dealt with as follows. One of the methods is any one or two of a fine powder amount of 0.25 mm or less in a sintering compounding raw material, a fine coke powder amount, an average diameter of fine coke powder, a fine coke amount of 0.25 mm or less, and an operation negative pressure. Performing one or more actions. Thus, the purpose can be achieved by adjusting the amount of fine powder, improving the combustibility of coke breeze, adjusting the effect of heat, adjusting the cooling rate during melt solidification, and the like. Another method is to use basicity (CaO / SiO
₂ ), alumina (Al ₂ O ₃ ) content, silica (SiO
₂ ) Any one of content and magnesia (MgO) content
An adjustment of a component or two or more components. C
high aO / SiO ₂ , Al ₂ O ₃ , SiO ₂ , MgO
However, it is necessary to make adjustments in consideration of the strength of the sinter, the reduction pulverizability, and the component adjustment of the slag flowing out of the tap hole of the blast furnace.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below with reference to embodiments. Table 1 shows the blast furnace operation results according to the present invention in comparison with the conventional method. The target blast furnace is a medium-sized blast furnace having an inner volume of 3000 m ^3, the use ratio of sinter in iron ore is 75 wt%, (SiO ₂ ) = 5.5 wt% in sinter, (Al ₂ O ₃ ) =
1.9 wt%, (MgO) = 1.5 wt%, (CaO /
(SiO ₂ ) = 1.9. Pulverized coal injection amount 1
The hot metal was manufactured at 6000 t / day while maintaining the fuel ratio at 40 kg / t and the fuel ratio at 500 kg / t. At this time, when measured by a mercury intrusion porosimeter, the average diameter (MS) of the open pores of 300 μm or less was in the range of 0.10 to 0.25 μm.

[0014]

[Table 1]

(Example 1) When the pulverized coal injection rate is increased to 180 kg / t while keeping the fuel ratio at 500 kg / t, the components in the sinter are kept as they are, and the amount of 0.1% in the sintering compound raw material is maintained. By performing the two actions of the fine powder amount of 25 mm or less and the blending amount of coke breeze, the average diameter of the open pores of 300 μm or less measured by a mercury intrusion porosimeter (M
5 is an operation example according to the present invention in which S) was adjusted to a range of 0.08 to 0.15 μm. Compared to Comparative Example 1, the fuel ratio is low and the tapping amount is large. (Example 2) When the pulverized coal injection rate is increased to 180 kg / t while keeping the fuel ratio at 500 kg / t, the sintering operation is kept in the conventional method, and the sintering operation (SiO ₂ ) = 5 .
3 ± 0.2 wt%, (Al ₂ O ₃ ) = 1.9 wt%,
(MgO) = 1.3 ± 0.2 wt%, (CaO / SiO
₂ ) An operation according to the present invention in which the average diameter (MS) of the open pores of 300 μm or less measured by a mercury intrusion porosimeter was adjusted to a range of 0.05 to 0.15 μm by adjusting the composition to 2.0. It is an example. Compared to Comparative Example 1, the fuel ratio is low and the tapping amount is large. (Comparative Example 1) When the pulverized coal injection rate was increased to 180 kg / t while keeping the fuel ratio at 500 kg / t, the components in the sinter were left as they were, and the sintering operation was also the conventional method. It is an operation example by a conventional method. As compared with the first and second embodiments, the fuel ratio has to be increased and the production amount is reduced.

[0016]

As described above, according to the present invention, the average diameter of the open pores having a size of 300 μm or less in the sintered ore is not more than 0.3 μm.
By adjusting the sintering operation so as to be in the range of 0.5 to 0.15 μm or adjusting the sinter composition, the permeability of the fusion layer formed by this sinter becomes good, and the lower part of the blast furnace The air permeability is improved, the operation of the blast furnace can be stably maintained, and an increase in pulverized coal injection, an improvement in productivity, and a decrease in fuel ratio can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a time-pressure loss curve for calculating an S value as an index for evaluating the high-temperature properties of a sintered ore in the present invention.

FIG. 2 is a diagram showing a relationship between an S value and a lower K value for determining a range in which the blast furnace has low permeability in the lower part of the furnace and determining an upper limit of the S value in the present invention.

FIG. 3 is a diagram showing a relationship between MS and S value for determining an appropriate range of average diameter (MS) of open pores of 300 μm or less in the present invention.

Claims (2)

[Claims] 1. The method according to claim 1, wherein the average diameter of the open pores of 300 μm or less is 0.
A method of operating a hard furnace using a sintered ore having good high-temperature properties, comprising charging a sintered ore having good high-temperature properties of from 0.5 to 0.15 μm from the furnace top of the hard furnace. 2. 150 kg / t of pulverized coal from the tuyere of the blast furnace
In the method of operating a hardened furnace, the sintered ore having a high temperature property having an average diameter of open pores of 300 μm or less of 0.05 to 0.15 μm is charged from the top of the hardened furnace. A method of operating a solid furnace using a sintered ore with excellent high-temperature properties.