JP2000336410A - Production of ironmaking raw material, ironmaking raw material and operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an agglomerate having scarcely reductively powdering and good reducibility by pre-reducing hematite ore to change magnetite powdery ore and agglomerating the powdery ore. SOLUTION: The pre-reducing temp. of the hematite ore is desirable to <750 deg.C. Further, when the magnetite powdery ore is agglomerated, carbon is desirable to contain. Concretely, the carbon is beforehand contained in the hematite ore and when the magnetite powdery ore is agglomerated, the carbon quantity may be increased. The obtd. agglomerate is not made to reduced powdering and has good high temp. property and good reducibility. Because in the case of executing the pre-reduction at <750 deg.C, many fine pores are formed and the total porosity becomes high. Further, the magnetite powdery ore is agglomerated into small grains having 3-10 mm grain diameter and the agglomerate combining plural grains has the best reducibility. That is, the smaller the single grain for agglomerate is, the higher the reducibility of the agglomerate is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a raw material for ironmaking, a raw material for ironmaking, and a method for operating a blast furnace. The present invention relates to a method for producing a raw material, a raw material for producing iron, and a method for operating a blast furnace into which the agglomerate is charged.

[0002]

2. Description of the Related Art Conventionally manufactured sinters vary in reductive powdering index (RDI value).
Reduction powdering occurs in the reduction region of 00 ° C to 700 ° C. In addition, pellets and lump ores, which are ores, have a reduced amount of reduced dusting compared to sintered ore, but reduced dusting occurs in the furnace, and the agglomerate ore that does not cause reduced dusting in the conventional technology Does not exist.

On the other hand, in the operation of a blast furnace, it is necessary to optimize the temperature distribution of the massive band portion in the furnace, in particular, to optimize the length of the low-temperature region of 500 ° C. to 800 ° C. in the height direction of the massive band portion. And reducing gas utilization rate,
It is extremely important in reducing the fuel ratio. That is, 5
The low-temperature range of 00 ° C to 800 ° C is the temperature range in which reduction and pulverization of iron sources such as sintered ore and agglomerate charged in the furnace are most likely to occur. If you do
It was necessary to implement measures to reduce reductive powder from the viewpoint of stable operation of the blast furnace.

[0004] In the conventional blast furnace operation, when it is recognized that the above-mentioned low-temperature region exists in the furnace, as a means for suppressing the reduction and pulverization of the sinter ore and improving the permeability, the sinter ore resistance is improved. The reduction of the reduction powder index (RDI) and the adjustment of the distribution of the charge are attempted, but in many cases, an increase in the fuel ratio leads to the reconstruction of the conditions inside the furnace.

[0005]

However, the reduction in RDI as a countermeasure against reduction and pulverization of the sinter ore tends to deteriorate the reducibility of the sinter, and the reduction efficiency reduces the blast furnace fuel ratio. And the production cost of sintered ore tends to increase. In addition, in order to stably continue the operation at a low fuel ratio in the future, it is necessary to develop agglomerate ores that are hardly reduced and pulverized and have good reducibility.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a method for producing a raw material for ironmaking, which is capable of producing agglomerate ore having little reducible pulverization and good reducibility, and a method for producing a raw material produced by this method. It is an object of the present invention to provide a method of operating a blast furnace capable of stably continuing operation at a low fuel ratio by charging an iron raw material and the raw material.

[0007]

In order to achieve the above object,
The method for producing a raw material for producing pig iron according to the present invention is to reduce hematite ore into magnetite powder ore and agglomerate the powder ore to produce agglomerate ore.

In the blast furnace operating method, it is preferable that the hematite ore has a pre-reduction temperature of less than 750 ° C.

When agglomerating the magnetite powder ore, it is preferable to include carbon. In this case, it is more preferable to include carbon in the hematite ore and to increase the amount of carbon when agglomerating the magnetite powder ore.

Further, it is preferable to agglomerate the magnetite powder ore into small grains and combine a plurality of grains to produce agglomerate ores.

[0011] The ironmaking raw material according to the present invention is produced as an agglomerate ore by any of the above methods.

Further, the method for operating a blast furnace according to the present invention comprises:
In a blast furnace operating method in which raw materials and fuel are charged from the furnace top and the air is adjusted from the tuyeres to make iron, the hematite ore is preliminarily reduced to magnetite powder ore as a raw material, and the powder ore is agglomerated. Charged agglomerate is charged.

In the blast furnace operating method, it is preferable that the hematite ore has a pre-reduction temperature of less than 750 ° C.

When agglomerating the magnetite powder ore, carbon is preferably contained. In this case, it is more preferable to include carbon in the hematite ore and to increase the amount of carbon when agglomerating the magnetite powder ore.

Further, it is preferable that the agglomerate ore is formed by agglomerating magnetite powder ore into small grains and combining a plurality of grains.

According to the present invention, the fact that the ironmaking raw material to be charged into the blast furnace is magnetite ore is not reduced and powdered. In addition, magnetite fine ore is produced by pre-reduction of hematite ore because, in the case of naturally occurring magnetite fine ore, almost no pores are present in the magnetite particles, so that even if agglomeration occurs, This is because there is little reduction in the reduction.

The prereduction temperature of the hematite ore is 750 ° C.
The reason for the lower limit is to actively produce hemispherical magnetite containing many fine pores in the process of reducing hematite to magnetite. When the pre-reduction temperature is 750 ° C. or higher, the diffusion of Fe atoms is accelerated. Therefore, in the process of reducing hematite to magnetite, acicular magnetite having few fine pores tends to be generated, and the porosity tends to decrease. This is because it is not possible to obtain an agglomerate ore having a high density. The carbon is included when agglomerating the magnetite powder ore in order to enhance the reducibility. Furthermore, the agglomeration of magnetite powder ore into small grains and combining multiple grains to form agglomerate ore is because the smaller the agglomerate particles, the higher the reducibility and the irregular shape. This is because the movement is suppressed and the distribution of the inserted object can be controlled.

As described above, the agglomerate ore having little reducible pulverization and good reducibility is developed, and is charged from the furnace top as a raw material for making iron, thereby stabilizing the low fuel ratio operation of the blast furnace. And can continue.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to the embodiments.

First, the blast furnace used in the operation method of the present invention will be described. FIG. 1 is a schematic diagram showing the situation inside the blast furnace. As shown in the figure, the blast furnace 1 has a bottomed cylindrical shape whose diameter is gradually reduced toward the top, and a raw material 2 such as iron ore and a solid fuel 3 such as coke and coal are loaded from the furnace top. Oxygen and pulverized coal are blown together with hot air from the tuyere 4 provided at the lower part of the side wall to perform iron making. Tuyere 4
The diameter of the tuyere, the length of protruding in the furnace, the blowing pressure, and the like can be adjusted, and the space of the raceway 5 is formed.

The core 6 located at the lower part in the furnace is a layer filled with the solid fuel 3 and receives the buoyancy from the hot metal 7 and the slag 8 so that the lower surface floats in the hot metal or sinks to the furnace bottom depending on the buoyancy and the load. are doing.

Above the shaft portion of the blast furnace, a massive zone 9 in which ore and coke are dried and preheated by the rising gas is formed, and an indirect reduction of the ore and a reaction of solution loss of the coke occur. In addition, in the upper part of the blast furnace 1,
A furnace top charging device (not shown) for charging materials such as raw materials and fuel into the furnace is provided. Further, a duct (not shown) for introducing gas discharged from the upper part of the blast furnace 1 is connected to the upper part of the blast furnace 1, and a volatile component recovery device and the like are interposed in this duct.

Using such a blast furnace 1, the operation method of the blast furnace according to the present embodiment is carried out as follows.

It is considered that the reduction and pulverization of ores changes the crystal structure in the process of reduction from hematite to magnetite, and this change causes cracks to occur, leading to pulverization. Therefore, reducing hematite, calcium ferrite,
Methods have been proposed to promote the formation of magnetite.
Further, even when using magnetite powder ore as a raw material, hematite is generated in the process of use for sintering, so that reduction pulverization cannot be suppressed.

The method of operating a blast furnace according to the present embodiment is a method for manufacturing agglomerate ore charged as a raw material.
e ₂ O ₃ ) is pre-reduced to reduce magnetite powder ore (Fe ₃
O ₄₎ were prepared and were directed to agglomerating the fine ore. This utilizes the fact that, as shown in FIG. 2, when the raw material is magnetite ore, it does not reduce and powder even in a low temperature range of 500 ° C. to 800 ° C.

The prereduction of hematite ore to produce magnetite powder ore is based on the premise that naturally occurring magnetite powder ore has almost no pores in the magnetite particles. This is because even if agglomeration occurs, there is little improvement in reducibility. As the pre-reduction method in the present invention, a known pre-reduction technique can be adopted.

Regarding the pre-reduction temperature of the hematite ore, the amount of fine porosity varies depending on the pre-reduction temperature. As shown in FIG. 3, at the pre-reduction temperature of 750 ° C. or higher, the porosity tends to decrease. Therefore, it is preferable that the pre-reduction temperature is lower than 750 ° C. in order to obtain a highly reducible agglomerate.

When agglomerating the magnetite powder ore, it is preferable to contain carbon. The inclusion of carbon is for enhancing the reducibility. Specifically, it is conceivable that carbon is contained in the hematite ore, and the amount of carbon is increased when agglomerating the magnetite powder ore.

The present inventors have conducted an investigation using a blast furnace reaction simulator proposed in Japanese Utility Model Publication No. 1-27038 and obtained the following findings. Incidentally, the reaction simulator in the blast furnace in the same gazette is a study on the in-furnace reducibility, reduced pulverizability, and molten dropping properties when ores and scrap are mixed and used. It has a furnace core tube that conducts the reducing gas from the lower part and makes the reducing gas and the ore in countercurrent contact with each other, and a heater surrounding a part of the furnace core tube and movably provided in the downstream direction of the reducing gas. Device.

First, it was confirmed that the agglomerate produced according to the present invention was not reduced to powder. Secondly, the agglomerate obtained by agglomerating the magnetite powder ore produced at a pre-reduction temperature of the hematite powder ore of less than 700 ° C. had good reducibility under the same agglomeration conditions. This is 70
Preliminary reduction at a temperature of less than 0 ° C. results in the generation of fine ore having a large number of fine pores of about 1 μm and a high total porosity.

Third, the magnetite powder ore produced by pre-reduction of the magnetite powder ore is agglomerated into small grains having a particle size of 3 to 10 mm, and the agglomerate ore in which a plurality of grains are combined has the best reducibility. is there. That is, reducing the single particles of agglomeration can increase the reducibility. Fourth, it was confirmed that not only the reducibility but also the high-temperature properties were good as compared with ordinary sintered ores.

As described above, it was found that the agglomerate ore employed in the present embodiment was not reduced to powder and had good reducibility. As described above, by developing agglomerate ore having little reducible pulverization and good reducibility, and charging it from the furnace top as a raw material for making iron, a low-temperature region of 500 ° C to 800 ° C in the furnace. Exists, the agglomerate ore is not reduced and powdered, and its reducibility is good, so that the low fuel ratio operation of the blast furnace can be stably continued.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[Embodiment 1] The target blast furnace in this embodiment is a medium-sized blast furnace having an inner volume of 3000 m ³ ,
00 ° C., blast humidity 25g / Nm ³ -air, oxygen-enriched amount 0.013Nm ³ / Nm ^{3 -air,} pulverized coal blowing amount 1
Under the condition of 80 g / Nm ³ -air, while maintaining the tuyere front flame temperature at 2100 ° C.,
/ Day. In Example 1, in the method for producing agglomerate ore to be charged as a raw material for ironmaking, hematite ore was added to 750
Preliminary reduction was performed at less than 0 ° C. to produce a magnetite powder ore, and agglomeration of the powder ore was blended at 30%.

Table 1 shows, as Example 1, the results of comparison between the operation method using 30% of magnetite agglomerate ore and the conventional method.

[Table 1]

The index of reducibility (JIS-RI) and the index of resistance to chemical reduction (RDI) are higher than those of commonly used sinter (JIS-RI: 65%, RDI: 38%). Magnetite agglomerate (JIS-RI: 75%, RD
(I: 2%) by using 30%, while maintaining good air permeability in the furnace, the shaft efficiency, which is the reaction index in the furnace, is 3% higher than before, and the coke ratio is reduced by 9 kg / t. It became possible.

Therefore, according to Example 1, it was confirmed that the agglomerate ore was not reduced and powdered and had good reducibility, so that the low fuel ratio operation of the blast furnace could be stably continued.

Example 2 Example 2 is the same as Example 1 except that hematite ore contains carbon and increases the amount of carbon when agglomerating magnetite powder ore. The carbon content in the magnetite powder ore is targeted at 20% or less for maintaining strength, and is adjusted to 4% here.

Table 2 shows the results of comparison between the conventional method and the operation method using 30% of magnetite agglomerate containing 4% of C in Example 1 as Example 2.

[Table 2]

The index to be reduced (JIS-RI) and the index to reduce powdering resistance (RDI) are calculated based on the commonly used sinter (J
Magnetite agglomerate (JIS-RI: 80%, RDI: 3) higher than IS-RI: 65%, RDI: 38%
%), The furnace efficiency, which is the shaft efficiency, is improved by 4% and the coke ratio can be reduced by 19 kg / t, while maintaining good air permeability in the furnace. Became. In Example 2, the reducibility of the magnetite agglomerate used in Example 1 was improved by 5% by adding C to the magnetite agglomerate used in Example 1 by 4%. The coke ratio was significantly improved.

Thus, according to the second embodiment, the agglomerate ore is not reduced and powdered, and the reducibility is better than that of the first embodiment. Therefore, it is possible to stably continue the low fuel ratio operation of the blast furnace. confirmed.

Example 3 In Example 3, magnetite powder ore produced by pre-reduction of hematite ore was used.
It is the same as Example 1 except that agglomeration was performed by agglomerating into small grains of 10 mm to 10 mm and combining a plurality of grains to produce agglomerate ore.

Table 3 shows the results of comparison between the operation method and the conventional method when the magnetite agglomerate of Example 1 was produced by combining a plurality of small agglomerates with a particle size of 3 to 10 mm as Example 3. ing.

[Table 3]

The reducibility index (JIS-RI) and reduction powdering resistance index (RDI) are calculated based on the commonly used sinter (J
Magnetite agglomerate (JIS-RI: 78%, RDI: 2) higher than that of IS-RI: 65%, RDI: 38%
%), 30% improvement in shaft efficiency, which is a reaction index in the furnace, and a coke ratio of 18 kg / t can be reduced while maintaining good air permeability in the furnace. Became. In Example 3, the magnetite agglomerate was manufactured by combining a plurality of small-size agglomerates having a particle size of 3 to 10 mm, thereby improving the reducibility of the magnetite agglomerate by 3% compared to Example 1. The coke ratio was significantly improved as compared with Example 1.

Therefore, according to the third embodiment, the agglomerate ore is not reduced and powdered, and the reducibility is better than that of the first embodiment, so that the low fuel ratio operation of the blast furnace can be stably continued. confirmed.

Example 4 In Example 4, magnetite powder ore produced by pre-reducing magnetite ore containing carbon in a hematite ore was agglomerated into small particles having a particle size of 3 to 10 mm, and a plurality of particles were combined. The agglomeration ore is manufactured by the same method as in the first embodiment.

Table 4 shows that, as Example 4, the magnetite agglomerate of Example 1 was changed into a small agglomerate having a particle size of 3 to 10 mm.
The result of comparison with the operation method when agglomerate ore is manufactured by combining a plurality of them is shown.

[Table 4]

The index of reduction (JIS-RI) and the index of resistance to reduction powdering (RDI) can be calculated by using the commonly used sinter (JI
Magnetite agglomerate (JIS-RI: 80%, RDI: 2) higher than S-RI: 65%, RDI: 38%
%), The furnace efficiency is improved by 5% and the coke ratio can be reduced by 26kg / t, while maintaining good air permeability in the furnace. Became.

In Example 4, the magnetite lump ore was combined with a plurality of small agglomerates having a particle size of 3 to 10 mm, and the amount of interior carbon was increased. The reduction was improved by 10%, and the coke ratio was able to be significantly improved as compared with the example. Therefore, the low fuel ratio operation of the blast furnace can be stably performed.

[0050]

As described above, according to the present invention,
Developed agglomerate ore with little reducible powder and good reducibility and charged it to blast furnace as raw material for making iron,
It has an excellent effect that the operation at a low fuel ratio can be stably continued.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the inside of a blast furnace used in an embodiment of a method for operating a blast furnace according to the present invention.

FIG. 2 is an explanatory diagram showing that magnetite ore is not reduced to powder in the present invention.

FIG. 3 is an explanatory diagram showing the relationship between the pre-reduction temperature and the porosity of hematite ore in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Raw material 3 Solid fuel 4 Tuyere 5 Raceway 6 Furnace 7 Hot metal 8 Slag 9 Lump belt

Claims (11)

[Claims] 1. A method for producing a raw material for ironmaking, comprising preliminarily reducing hematite ore into magnetite ore, and agglomerating the ore to produce agglomerate ore. 2. The pre-reduction temperature of the hematite ore is:
The method according to claim 1, wherein the temperature is lower than 750 ° C. 3. The method according to claim 1, wherein carbon is contained when agglomerating the magnetite powder ore. 4. The method according to claim 3, wherein carbon is contained in the hematite ore, and the amount of carbon is increased when agglomerating the magnetite powder ore. 5. The method according to claim 1, wherein the magnetite powder ore is agglomerated into small grains and a plurality of grains are combined to produce agglomerate ore. . 6. An ironmaking raw material produced by the method according to any one of claims 1 to 5. 7. A method for operating a blast furnace in which a raw material and a fuel are charged from a furnace top and air is adjusted from a tuyere to perform iron making, wherein a hematite ore is preliminarily reduced as a raw material into a magnetite powder ore. A method for operating a blast furnace, comprising charging an agglomerate ore obtained by agglomerating fine ore. 8. The pre-reduction temperature of the hematite ore,
The method for operating a blast furnace according to claim 7, wherein the temperature is lower than 750 ° C. 9. The blast furnace operating method according to claim 7, wherein carbon is contained when agglomerating the magnetite powder ore. 10. The method according to claim 9, wherein carbon is contained in the hematite ore, and the amount of carbon is increased when agglomerating the magnetite powder ore. 11. The method for operating a blast furnace according to claim 7, wherein the agglomerate ore is obtained by agglomerating magnetite powder ore into small grains and combining a plurality of grains.