JP2001107114A - Operation of blast furnace using highly reducible sintered ore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the lowering of fuel ratio and the improvement of production in a blast furnace by securing the reducibility of a sintered ore, raising an O/C ratio at the peripheral part of the furnace and improving the reducing efficiency in this zone when a large quantity of pulverized fine coal is blown in. SOLUTION: In an operational method of the blast furnace, by which the pulverized fine coal is blown from a tuyere part of the blast furnace, and also, iron raw material and carbonaceous material are charged from the furnace top part of the blast furnace, the high reducible sintered ore containing <5 wt.% SiO2, <1 wt.% MgO and <1.8 wt.% Al2O3 and having 1.8-2.5 basicity (CaO/SiO2) is charged from the furnace top part of the blast furnace, or in addition, together with the highly reducible sintered ore, massive iron ore having high content of Al2O3 and 10-35 mm grain diameter, is pre-mixed therewith and charged, or the powdery iron ore having high content of Al2O3 and <5 mm grain diameter is blown from the tuyere part of the blast furnace to adjust the Al2O3 content in slag flowing out from an iron tapping outlet of the blast furnace to 13-16 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace for reducing the fuel ratio and improving the productivity by securing the reducibility of the sinter which occupies most of the iron ore charged from the furnace top. Regarding the operation method.

[0002]

2. Description of the Related Art Conventionally, in blast furnace operation, pulverized coal which is inexpensive, has good flammability, and has a high calorific value has been used as an alternative to coke.
Japanese Patent Publication No. 40-23376 discloses a technique for injecting a fuel such as petroleum, heavy oil, or naphtha from a tuyere of a blast furnace to reduce the production cost and improve the productivity of hot metal. In recent years, in particular, pulverized coal injection has become the mainstream in terms of production cost, and has greatly contributed to a reduction in fuel ratio (cost reduction) and an improvement in productivity.

In such a pulverized coal injection operation,
Pulverized coal injected from the blast furnace tuyere in place of some coke is burned in the blast furnace, and a high calorific value is obtained due to good combustibility. The furnace heat of the blast furnace can be increased, and an efficient reduction reaction of iron ore can be performed. Therefore, the iron ore charged from the top of the blast furnace is easily reduced to a metallic state by the high-temperature reducing gas and melted to form hot metal, thereby contributing to an improvement in productivity of the blast furnace.

In the above pulverized coal injection operation,
When a large amount of pulverized coal of 100 kg / t or more is blown, the heat flow ratio (the ratio of the heat capacity of the solid to the heat capacity of the gas), which is an index of the heat reduction efficiency in the massive zone of the blast furnace, decreases, and the heat reduction is not sufficient. Conventionally, a high reduction rate-oriented operation has been performed in which the ratio of iron ore to coke (hereinafter referred to as O / C) at the time of charging the blast furnace raw material is increased.

Further, in recent blast furnace operations, the ratio of sinter to iron ore in the iron raw material charged from the top of the blast furnace has become extremely high, usually 60 to 80%. The reduction efficiency is substantially determined by the properties of the sinter such as reducibility. Therefore, even in the above-mentioned high O / C operation at the periphery of the furnace aimed at high reduction efficiency, the properties such as the reducibility of the sintered ore can be reduced by reducing the fuel ratio of the blast furnace,
It is very important for productivity improvement.

[0006] Generally, in the pulverized coal injection operation of a blast furnace, iron ore charged in the peripheral portion of the furnace is generated in a coke swirl combustion region (hereinafter, referred to as a raceway) of a blast furnace tuyere. Reaction heat transfer proceeds with the high-temperature reducing gas, and a cohesive zone is generated by softening and welding of the iron ore (the one generated at the periphery of the furnace is referred to as a root). It is desirable that the roots are stably present in the periphery of the lower furnace in normal blast furnace operation and do not change in position and thickness.

[0007] In the pulverized coal mass injection operation aimed at high reduction efficiency, the O / C around the furnace becomes extremely high as described above, so that the iron ore layer becomes thick and the sintered ore becomes blast furnace. Heat reduction in the process of descending inside is delayed, and as a result, FeO and silica (SiO2) remaining without being reduced combine to form a low melting point compound. Alumina (Al2 O3) in iron ore and sintered ore is added to the melt of the low melting point compound.
And magnesium (MgO) dissolve, and the remaining FeO further dissolves in the melt, thereby increasing the amount of the melt.

[0008] Since this melt has poor penetration of the reducing gas,
The increase in the amount of the melt further promotes the delay of the heat reduction of the sintered ore. Therefore, in the conventional pulverized coal large-volume injecting operation, in order to avoid the above-mentioned problem, an action to reduce the O / C in the furnace peripheral portion has to be performed.

In order to reduce the amount of the low-melting-point compound which causes a delay in the reduction of the sinter, the gangue components of the sinter, SiO2, Al2 O3, MgO, calcium (CaO), are reduced. It has been attempted in the past to reduce. However, among the gangue components in the sinter, CaO
Improves the strength and reducibility of the sintered ore, and improves the basicity (Ca
O / SiO2) is a component necessary for securing
The reduction of l2O3 leads to an increase in the cost of iron ore.

[0010] Further, SiO2 and MgO are necessary to secure the strength and reduced powderability of the sintered ore.
In particular, Al2 O3 in slag flowing out of the blast furnace taphole
It is also necessary to adjust the content of MgO and MgO to a predetermined range to secure the fluidity and desulfurization ability of the slag.
Therefore, there is a limit in reducing the gangue component in these sintered ores.

Therefore, conventionally, in the operation of injecting a large amount of pulverized coal, O / C in the periphery of the furnace cannot be increased due to the delay in reduction of the sinter, as described above. However, the amount of gas in the vicinity of the furnace becomes excessive, the heat dissipated in the furnace body increases, and problems such as the occurrence of an abnormal charge drop and a decrease in productivity have been encountered. Therefore, the margin of heating reduction in the periphery of the furnace obtained by injecting a large amount of pulverized coal cannot be effectively used, and the amount of pulverized coal to be injected must be regulated in order to improve the fuel ratio and productivity. Here, the furnace peripheral part refers to a region from the furnace wall to a distance of 15% of the furnace diameter.

In order to improve such a problem, the present inventors have invented a technique which has improved this point, and have already filed an application as Japanese Patent Application Laid-Open No. Hei 11-29803. The outline is, "When the large amount of pulverized coal is injected into the blast furnace, the reducibility of the sinter is secured, the O / C at the periphery of the furnace is increased, and the reduction efficiency of this region is improved. In order to achieve reduction and improvement in productivity, the contents of SiO2 and MgO in the sinter are less than 5.0 wt% and 1.0 w%, respectively.
t% and CaO / SiO2 of 1.8 to 2.5
By keeping the reducibility of the sinter good, the Al2 O3, M in the slag flowing out of the taphole is maintained.
In order to adjust the gO content, SiO2
A bulk auxiliary material containing O is charged, or SiO
2 ・ Blow in powdery auxiliary material containing MgO ”.

[0013]

The above-mentioned inventions have been able to solve the problems of the prior art to some extent, but the present inventors have aimed at reducing the reducibility of the sintered ore with the aim of further improvement. By increasing the O / C around the furnace when a large amount of pulverized coal is blown, the reduction efficiency in this area is increased, so that the fuel ratio of the blast furnace can be reduced and the productivity can be stably improved. Assigned.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional method, and its gist lies in the following means. (1) In a blast furnace operation in which pulverized coal is blown from the tuyere of the blast furnace and iron and carbon materials are charged from the top of the blast furnace, SiO2 is less than 5 wt%, MgO is less than 1 wt%, Al2 O3 Is less than 1.8 wt%, and the basicity (CaO / SiO2) is 1.8 to
A blast furnace operating method using a highly reducible sintered ore into which the highly reducible sintered ore of 2.5 is charged. (2) From the top of the blast furnace, together with highly reducible sintered ore,
A lump mass of iron ore having a large l2 O3 content and having a particle size of 10 to 35 mm is previously mixed and charged, and the Al2 O3 content in the slag flowing out of the blast furnace taphole is adjusted to 13 to 16 wt% (1). A blast furnace operating method using the highly reducible sintered ore described in the above.

(3) In order to adjust the content of Al 2 O 3 in the slag flowing out of the blast furnace tap hole within an appropriate range,
The mixing ratio of iron ore charged from the top of the blast furnace
A method for operating a blast furnace using the highly reducible sintered ore according to (2), which is adjusted by the content. (4) A highly reducible sintered ore is charged from the top of the blast furnace, and a particle having a large Al2O3 content is discharged from the tuyere of the blast furnace.
Blast furnace operation using highly reducible sintered ore according to (1), wherein fine iron ore having a diameter of less than 1 mm is blown and the Al2O3 content in the slag flowing out of the blast furnace taphole is adjusted to 13 to 16 wt%. Method.

(5) In order to adjust the content of Al 2 O 3 in the slag flowing out of the blast furnace tap hole within an appropriate range,
The mixing ratio of the powdered iron ore injected from the tuyere
3. A method for operating a blast furnace using the highly reducible sintered ore according to (4), wherein the sinter is adjusted by the content. (6) A method for operating a blast furnace using the highly reducible sintered ore according to (4) or (5), wherein the fine iron ore that has been preliminarily reduced by 40 to 90% is blown from the tuyere of the blast furnace. (7) A blast furnace operating method using the highly reducible sintered ore according to any one of (4) to (6), wherein the fine iron ore is previously mixed with pulverized coal and blown from the tuyere of the blast furnace.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the content of SiO2 in a sintered ore charged as iron raw material from the top of a blast furnace is 5%.
wt%, MgO content less than 1 wt%, Al2O
3 was limited to less than 1.8 wt%. When the sinter is reduced, the SiO2 in the sinter generates a solution composed of a low-melting-point compound by bonding with the remaining FeO, deteriorating the permeability of the reducing gas, and reducing the reduction of the surrounding sinter. Therefore, the content of SiO2 in the sinter was set to less than 5 wt% in order to reduce the amount of the solution in order to inhibit the property.

MgO in the sinter is dissolved in the low-melting-point compound melt to increase the amount of the melt. The content was less than 1 wt%. Al2O3 in the sinter generates a low melting point compound by bonding with FeO, or increases the amount of the solution by dissolving in the solution. In order to prevent this, its content is 1.8 wt%
Less than.

As described above, the SiO 2, Mg
By defining the contents of O and Al2 O3 to the above-mentioned amounts, the amount of the low melting point melt composed of FeO and SiO2, MgO and Al2 O3 is reduced, and the reduction of the reducibility of the sintered ore is suppressed. And the reducibility can be improved. Because of the effect of improving the reducibility of the sintered ore, the reduction of the sintered ore is promoted and the amount of residual FeO itself forming a low melting point compound is reduced, so that the amount of the melt can be reduced synergistically, and The reducibility can be further improved.

These effects are particularly noticeable in the periphery of the furnace where the O / C is high and the reduction delay occurs due to high pulverized coal injection or the like. However, the content of SiO 2 in the sintered ore is 5 wt% or more, and the content of MgO is When the amount is 1 wt% or more and the Al2O3 content is 1.8 wt% or more, the effect cannot be expected.

The SiO 2 content of the present invention is less than 5 wt%,
MgO content is less than 1 wt%, Al2O3 content is 1.
In order to produce a sintered ore having a content of less than 8 wt%, in the sintering raw material, for example, the compounding amount of an auxiliary raw material (for example, serpentine, peridotite, junite, etc.) containing a large amount of SiO 2 .MgO, Can be easily obtained by minimizing the blending amount of iron ore (for example, Australian iron ore) containing a large amount of iron ore.

From the viewpoint of improving the reducibility of the sintered ore, the lower limit of the content of each of SiO2, MgO and Al2 O3 in the sintered ore does not need to be particularly specified. However,
The content of SiO2, MgO and Al2 O3 in the sinter is effective in improving the strength, reduction and powdering properties of the sinter, and the fluidity and desulfurization ability of the slag. If the amount is reduced as specified in the above, the effect is undesirably reduced.

Therefore, in order to secure these effects, the present invention is further limited as follows. First, MgO and Al2 O3 in the sinter are effective in improving the strength and the reduction pulverizability. Therefore, when these components are reduced, the strength and the reduction pulverizability of the sinter decrease. . In order to solve this problem, in the present invention, the basicity (CaO / SiO2) of the sintered ore is further specified in the range of 1.8 to 2.5. The reason for this is that if the basicity is less than 1.8, the reducibility of the sinter decreases, and if it exceeds 2.5, the strength,
This is because it becomes difficult to ensure the reduction pulverizability.

Next, SiO2, MgO, Al in the sintered ore
Due to the decrease in the content of 2 O3, the amount of slag flowing out of the tap hole of the blast furnace is also inevitably reduced, and its fluidity and desulfurization ability are reduced. Therefore, in order to solve this problem, in the present invention, iron ore containing a large amount of SiO2, MgO and Al2O3 is preliminarily mixed with the sinter ore as a massive iron ore having a particle diameter of 10 to 35 mm. , SiO2 · Al2
The iron ore containing a large amount of O3 is blown from the tuyere of the blast furnace as fine iron ore having a particle size of less than 5 mm, so that the Al2O3 content in the slag flowing out of the blast furnace taphole is reduced to 13 to 16 wt.
% To ensure the fluidity and desulfurization capacity of the slag.

That is, when the above-mentioned massive iron ore is preliminarily mixed with the highly reducible sinter ore and charged from the blast furnace top, in the present invention, the particle diameter of the massive iron ore is set to a range of 10 to 35 mm. limit. The reason is that if the particle size exceeds 35 mm, the reduction of the lump iron ore becomes difficult to proceed, and if the particle size is less than 10 mm, the reduction does not interfere with the progress of the reduction, but the permeability of the blast furnace decreases. .

By adopting such a method, SiO 2
And high reducible sinter having a low content of Al2 O3, when a massive iron ore having a high content of SiO2 and Al2 O3 is mixed and charged, the sinter is reduced to reduce the low melting point compound. However, since the amount of generated melt is small, it does not hinder the progress of the reduction of the surrounding sinter by the melt, and the reaction with the melt proceeds in that state to generate slag. Can be generated. As a result, it is possible to avoid reducing the Al2O3 content in the slag flowing out of the taphole, and it is possible to secure the fluidity and desulfurization ability of the slag to appropriate values.

According to the present invention, the content of Al2 O3 in the slag flowing out of the taphole by using these methods is determined to be 13 to 16 wt% at which the slag fluidity and desulfurization ability are improved.
Is adjusted in the range of. In addition, when the above-mentioned massive iron ore is charged, if it is charged alone without mixing with the sintered ore, there is a fear that the component segregation of SiO2 and MgO may be caused. is necessary.

The content of Al 2 O 3 in the slag is 13-16.
As a method for ensuring an appropriate range of wt%, for example, a lump iron ore such as an Australian iron ore containing a large amount of SiO2 and Al2 O3 is used, and when the iron ore is mixed with a highly reducible sintered ore, the amount thereof is adjusted. Adjustment is performed.

Next, when the fine iron ore is blown from the tuyere of the blast furnace, the particle size of the fine iron ore is limited to less than 5 mm. The reason is that when the particle size of the fine iron ore is 5 mm or more, it is difficult to melt and slag in the raceway and the effect of blowing cannot be obtained. Even when fine iron ore is blown from the tuyere of the blast furnace, SiO2 and Al2
Due to the small amount of low melting point melt, which is the effect of using a highly reducible sintered ore having a low O3 content, SiO2 and A
Slag can be produced by reacting with fine iron ore having a high content of l2 O3. As a result, similar to the mixed charging of massive iron ore, Al2 O3 in slag flowing out of the taphole
Lowering of the content is avoided, and the fluidity and desulfurization ability of the slag can be secured.

When this powdery iron ore is blown from the tuyere of the blast furnace, SiO2 and Al2O such as Australian iron ore are used.
By using a lump iron ore containing a large amount of 3 in the form of powder and adjusting the amount of air blown from the tuyere of the blast furnace, the Al2O3 content in the slag improves the slag fluidity and desulfurization ability. -16% by weight. If the Al2 O3 content in the slag is out of the range of 13 to 16% by weight, the slag fluidity and deaeration cannot be kept good.

In the present invention, it is preferable to use iron ore preliminarily reduced to 40 to 90% when blowing fine iron ore from the tuyere of the blast furnace. By doing so, the amount of heat required for reducing the sinter ore ore charged from the top of the blast furnace can be reduced, and accordingly, the temperature in the raceway is increased, and the temperature in the raceway is increased. Melting and slag formation can be promoted. When pulverized iron ore is blown from the tuyere of the blast furnace, it may be blown from a dedicated lance separate from the lance for blowing pulverized coal, or may be mixed with pulverized coal in advance and blown from the same lance. The effect of melting and slag formation in the raceway can be enjoyed.

SiO 2 and Al 2 O 3 used in the present invention
Lumped iron ore or fine iron ore, which contains a large amount, is reduced in SiO2 and Al2 in the formulation when producing highly reducible sintered ore.
Since it is possible to use iron ore having a low O3 content (eg, Australian iron ore), it is also effective in reducing raw material costs.

[0033]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples. The blast furnace used was a medium-sized blast furnace with an inner volume of 3000 m ³ , the ratio of sinter used in iron ore was 75 wt%, (SiO 2) = 5.5 wt% in sintered ore, (MgO) = 1.5
wt%, CaO / SiO2 = 1.75, and a fuel ratio of 5
The operation was performed while maintaining the pulverized coal injection rate at 140 kg / t and the pulverized coal injection rate at 6000 t / day. At this time, the raw material for sintering is SiO2.Al2
30.0wt% of Australian iron ore containing a large amount of O3, SiO
2 2.0% by weight of secondary material (serpentine) containing much MgO
It was blended. (A) in the slag flowing out of the taphole
l2 O3) = 14.5 wt%, (MgO) = 6.5 wt
% Content was retained.

(Example 1) The amount of pulverized coal injected from the tuyere of the blast furnace was increased to 180 kg / t, and the fuel ratio was increased to 49 kg / t.
0kg / t, 30.0wt%
Australian iron ore that had been blended was reduced to 25.0 wt%,
The serpentinite, which had been blended at 2.0 wt% in the raw material for sintering, was reduced to 1.0 wt%, and (SiO2) = 4.8 in the sinter.
wt%, (MgO) = 0.9 wt%, CaO / SiO2
= 1.9. As a result, (Al2 O3) in the slag flowing out of the taphole = 15.5 wt%, (MgO) =
It became 6.5 wt%. Compared with Comparative Example 1 which is almost the same as the operation example according to the present invention, the fuel ratio can be reduced and the tapping amount can be increased.

(Example 2) The amount of pulverized coal injected from the tuyere of the blast furnace was increased to 180 kg / t, and the fuel ratio was increased to 50 kg / t.
0 kg / t, the Australian iron ore blended in the sintering blending material was reduced to 35.0 wt% to 25.0 wt%, and the serpentinite blended in the sintering blending material was reduced to 2.0 wt%. .0
wt%, and in the sintered ore (SiO2) = 4.8 wt%
%, (MgO) = 0.9 wt%, CaO / SiO2 =
1.9. At this time, (Al2 O3) = 14.5 wt% and (MgO) = 5 in the slag flowing out of the taphole.
15 to 35 m from the top of the blast furnace so as to be 0 wt%
This is an operation example according to the present invention in which m massive Australian iron ore was previously mixed and charged in an amount of 3.8 wt% of the charged iron ore with the sinter. Compared to Comparative Example 1, the fuel ratio was low,
The tapping amount was large.

(Example 3) The amount of pulverized coal injected from the tuyere of the blast furnace was increased to 180 kg / t, and the fuel ratio was increased to 49 kg / t.
Reduced to 5kg / t, 30.0wt%
Australian iron ore that had been blended was reduced to 25.0 wt%,
The serpentinite, which had been blended at 2.0 wt% in the raw material for sintering, was reduced to 1.0 wt%, and (SiO2) = 4.8 in the sinter.
wt%, (MgO) = 0.9 wt%, CaO / SiO2
= 1.9. At this time, (Al2 O3) in the slag flowing out of the taphole = 14.5 wt%, (MgO) =
This is an operation example according to the present invention in which fine iron ore having a diameter of less than 5.0 mm from the tuyere portion is blown at a rate of 60 kg / t with a lance separate from pulverized coal so as to be 5.0 wt%. Comparative Example 1
Compared to, the fuel ratio was low and the tapping amount was large.

(Example 4) The amount of pulverized coal injected from the tuyere of the blast furnace was increased to 180 kg / t, and the fuel ratio was increased to 49 kg / t.
Reduced to 5kg / t, 30.0wt%
Australian iron ore that had been blended was reduced to 25.0 wt%,
The serpentinite, which had been blended at 2.0 wt% in the raw material for sintering, was reduced to 1.0 wt%, and (SiO2) = 4.8 in the sinter.
wt%, (MgO) = 0.9 wt%, CaO / SiO2
= 1.9. At this time, (Al2 O3) in the slag flowing out of the taphole = 14.5 wt%, (MgO) =
Fine iron ore less than 5.0 mm from the tuyere portion was preliminarily reduced by 65% in an amount of 60 kg / t so as to be 5.0 wt%, and preliminarily mixed with pulverized coal, and blown in the same lance. It is an operation example by this invention. Compared with Comparative Example 1, the fuel ratio was low and the tapping amount was large.

(Comparative Example 1) The amount of pulverized coal injected from the tuyere of the blast furnace was increased to 180 kg / t, and the fuel ratio was increased to 51 kg / t.
5kg / t, 30.0wt%
With the Australian iron ore blended as it is and the serpentine blended with 2.0 wt% in the sintering raw materials as it is, the sinter ore (SiO2) = 5.5 wt%, (MgO)
= 1.5 wt%, CaO / SiO 2 = 1.75 is an operation example according to the conventional method in which the operation was continued. Example 1,
Compared to 2, 3, and 4, the fuel ratio had to be increased, and despite the increase, the production volume decreased. The results of the above blast furnace operation were summarized, compared with Examples and Comparative Examples, and are shown in Table 1.

[0039]

[Table 1]

[0040]

As described above, in the present invention, the content of SiO2 in the sintered ore is less than 5 wt% and the content of MgO
Is less than 1 wt% and CaO / SiO2 is 1.8 to 2.
By setting the value to 5, the reducibility of the sintered ore when a large amount of pulverized coal is injected can be maintained well, so the O / C around the furnace is increased, the reduction efficiency is improved, the fuel ratio of the blast furnace is reduced, and the production is reduced. Stability can be stably improved. Also, a lump of iron ore having a particle diameter of 10 to 35 mm is previously mixed and charged from the top of the blast furnace, or powdery iron ore having a particle diameter of less than 5 mm is blown from the tuyere of the blast furnace, thereby allowing the blast furnace to exit. The content of Al2 O3 in the slag flowing out of the pig iron can be adjusted to 13 to 16 wt%, and slag having good fluidity and desulfurization ability can be produced.

Claims (7)

[Claims] 1. In a blast furnace operation in which pulverized coal is injected from a tuyere of a blast furnace and iron and carbon materials are charged from the top of the blast furnace, SiO2 is less than 5 wt% from the top of the blast furnace.
A highly reducible sintered ore containing less than 1 wt% of MgO and less than 1.8 wt% of Al2 O3 and having a basicity (CaO / SiO2) of 1.8 to 2.5 is charged. Blast furnace operation method using highly reducible sintered ore. 2. A high-reducible sintered ore, together with a lump iron ore having a large Al2 O3 content and a particle diameter of 10 to 35 mm, are charged and charged from the top of the blast furnace and discharged from the blast furnace taphole. The blast furnace operating method using a highly reducible sintered ore according to claim 1, wherein the content of Al2O3 in the slag is adjusted to 13 to 16 wt%. 3. In order to adjust the Al2 O3 content in the slag flowing out of the blast furnace taphole within an appropriate range, the mixing ratio of the iron ore charged from the top of the blast furnace is adjusted by the Al2 O3 content. A blast furnace operating method using the highly reducible sintered ore according to claim 2. 4. A highly reducible sintered ore is charged from the top of the blast furnace, and fine iron ore having a large Al2 O3 content and less than 5 mm in diameter is blown from the tuyere of the blast furnace, and the blast furnace tapping port is provided. The content of Al2 O3 in the slag flowing out of
%. The method for operating a blast furnace using a highly reducible sintered ore according to claim 1, wherein the sintering rate is adjusted to%. 5. The mixing ratio of the powdered iron ore blown from the blast furnace tuyere is adjusted by the Al2 O3 content in order to adjust the Al2 O3 content in the slag flowing out of the blast furnace taphole within an appropriate range. A method for operating a blast furnace using the highly reducible sintered ore according to claim 4, wherein 6. The highly reducible sintered ore according to claim 4, wherein fine iron ore which has been preliminarily reduced by 40 to 90% is blown from a tuyere of the blast furnace. Blast furnace operation method. 7. The powdery iron ore is preliminarily mixed with pulverized coal and blown from a tuyere of a blast furnace.
A blast furnace operating method using the highly reducible sintered ore according to any one of the above.