JP2014015653A - Pig iron production method and pig iron production furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pig iron production method and a pig iron production furnace capable of producing pig iron in an exhaust carbon gas amount more reduced than that in the conventional blast furnace.SOLUTION: Iron ore (10) is charged to the furnace wall part of a vertical furnace, and simultaneously, a carbonaceous material (70) is charged from furnace opening part to a furnace central part to form the carbonaceous material (70) so as to be columnar and, further, to form the iron ore (10) to the outside of the carbonaceous material (70), dust coal is blown from the tuyere (9) of a furnace bottom part together with an oxygen gas, the carbonaceous material and the dust coal are burnt to produce a reduction gas, and the iron ore is reduced with this reduction gas to produce pig iron.

Description

  The present invention relates to a method for manufacturing pig iron and a vertical pig iron manufacturing furnace for carrying out this method.

Historically, the method of producing pig iron using a tall blast furnace with a circular horizontal cross-section has historically been that in 1709, Ebraham Derby introduced coke and iron ore into a vertical blast furnace instead of charcoal, and reduced the iron ore. It is said that it begins with the manufacture of pig iron.
This method has been developed since then, and as shown in FIG. 1 shown in Non-Patent Document 1, the blast furnace 1 is charged with the sintered ore calcined by the sintering machine 4 and the coke produced by the coke oven 2, and the hot blast furnace 3 The air heated in is blown from the tuyere and iron ore is reduced to produce pig iron (see Non-Patent Document 1).
Thus, the conventional blast furnace requires at least a coke oven, a hot air furnace, and a sintering machine. Among these, the sintering machine melts and solidifies iron ore in advance, and thus has the effect of reducing the burden on the blast furnace. However, since it requires heat, it increases CO ₂ gas generation.

Fig. 1 shows an outline of the amount of CO ₂ gas generated per ton of pig iron produced when producing pig iron. The amount of CO ₂ emitted to produce 1 ton of pig iron is shown in Fig. 1. In large quantities.
Total CO ₂ gas volume: 2031 kg / ton iron (100%)
The amount of CO ₂ gas generated from the amount of heat supplied to the lower processes such as steelmaking and rolling: 34.4%
CO ₂ gas volume for power plants: 0.6%
Total CO ₂ gas volume: 35.0%
This amount of CO ₂ gas (Mass%) can be reduced by using another heat source.

On the other hand, regarding the blast furnace main body, referring to the following figures, there is a possibility that the amount of CO ₂ gas consumed in the coke oven (11.8%) and the hot stove (17.4%) may be omitted.
Coke oven 11.8%
Lime firing furnace 3.4%
Hot stove 17.4%
Sintering furnace 13.1%
Total CO ₂ volume (related to blast furnace) 32.6% (All figures are Mass%)
Further, the coke oven is constructed of expensive silica bricks, and the produced coke is cooled after dry distillation. In addition, the hot stove heats the lattice bricks and heats the air up to 1200 degrees, so that CO ₂ gas is also generated (see, for example, Non-Patent Document 2).
Feramu vol.16, No8, 2011, P543〜549 Steel Handbook 3rd edition

Therefore, pig iron is produced with less CO ₂ gas generation than before, and it is necessary to reduce CO ₂ that causes the global environment to be warmed. It is necessary to greatly reduce pig iron production costs. Considering the above heat balance from such a viewpoint, at least 32.6% of CO ₂ gas related to the blast furnace can be reduced in a process without a coke oven, a lime firing furnace, or a hot air furnace.
A lime kiln is necessary because it decomposes limestone and adjusts the basicity of the slag, but a process without at least a coke oven and hot air oven is desirable.

Further, in the conventional blast furnace process, air is blown from the tuyere, so that the sensible heat of the blast furnace gas containing about 55 vol% of nitrogen increases, so that N ₂ gas is discharged accordingly. Further, the conventional blast furnace gas contains about 15 vol% CO ₂ gas and about 30 vol% CO gas.
Therefore, the present invention does not use coke from a coke oven with high construction cost as much as possible, does not use a hot blast furnace, uses iron ore and carbon as raw materials for iron ore, and has a low construction cost. Providing a method of producing pig iron in a furnace and a vertical furnace (hereinafter referred to as AK furnace) used for this, pig iron is produced with a smaller amount of exhausted carbon gas than a conventional blast furnace, causing a warming environment. The purpose is to reduce CO ₂ gas emissions.

In order to achieve the above object, in the pig iron manufacturing method according to the present invention, the iron ore (10) is charged from the furnace port portion into the furnace wall portion of the vertical furnace having the shaft portion, and at the same time, the carbonaceous material ( 70) so that the carbon material (70) is formed in a columnar shape in the center of the furnace and the iron ore (10) is formed outside the carbon material (70). It is characterized in that pig iron is produced by blowing pulverized coal together with oxygen gas from the mouth (9), burning the carbonaceous material and the pulverized coal to generate a reducing gas, and reducing the iron ore with the reducing gas. To do.
In this case, another tuyere for gas injection is provided in the shaft portion, and the exhaust gas discharged from the furnace port portion is heated to a predetermined temperature or higher, or the LD gas of the LD converter is added to the exhaust gas to It may be heated to a predetermined temperature or higher and blown into the other tuyere.

It is preferable to charge the iron ore in a layered manner on the carbon material (70) charged in the central portion at a predetermined interval.
The iron ore is preferably a mixture of any one or more of pellets, sintered ores, and agglomerates.

The carbon material (70) is preferably one or more of coal, coke, and biomass.
The carbon material is preferably a carbon material in which coal is mixed in an amount of 30% by mass or more.
The coal is preferably processed into pellets or briquettes.
The oxygen gas preferably has a purity of 50 vol% or more.

Further, the present invention has a rectangular (22) or elliptical horizontal cross section, and from the bottom includes a furnace bottom, morning glory, furnace belly, shaft and furnace port, between the furnace bottom and morning glory. The iron ore is charged into the furnace wall portion from the furnace port portion, and at the same time, the carbon material (70) is charged from the furnace port portion to the furnace center portion so that the carbon material (70 ) Is formed in a columnar shape in the center of the furnace and the iron ore (10) is formed outside the carbonaceous material (70), and pulverized coal together with oxygen gas from the tuyere (9) Means for producing pig iron by blowing, burning the carbon material and the pulverized coal to produce a reducing gas, and reducing the iron ore with the reducing gas, and a vertical pig iron A manufacturing furnace can be provided.
In this case, the exhaust gas from the furnace port is heated to a predetermined temperature or higher, or the LD gas of the LD converter is added to the exhaust gas and heated to the predetermined temperature or higher, and blown into the shaft portion. Good.
Further, it is preferable that the morning glory portion has a cross-sectional area that continuously extends to the furnace bottom portion, and then the shaft portion has a cross-sectional area that gradually decreases toward the furnace port portion.

In the present invention, coal is charged from the furnace port, and high-cost coke is not used as much as possible. Therefore, the coke oven can be further miniaturized and the hot air furnace is not used. Pig iron can be produced in a new vertical furnace that can be manufactured at low cost. Along with this, pig iron is produced at a lower cost than conventional blast furnaces with less carbon emissions, and the amount of carbon dioxide emissions causing global warming adverse effects is reduced.
Further, in the conventional blast furnace process, air is blown from the tuyere, so that the sensible heat of the blast furnace gas containing about 75 vol% of nitrogen increases, so that N ₂ gas is discharged, but in the present invention, air is not used. Therefore, it is not necessary to discharge a large amount of N ₂ gas.

It is a diagram showing an outline of CO ₂ gas amount used and outline of pig iron manufacturing process according to the conventional blast furnace. It is a diagram showing the amount of CO ₂ gas is used in a conventional blast furnace. It is a vertical sectional view showing the distribution of the charge of the AK furnace used in the present invention. It is a horizontal sectional view of the rectangular type of the AK furnace used in the present invention. It is a vertical sectional view showing the distribution of charges in the vicinity of the furnace mouth, the shaft portion, and the tuyere in the AK furnace used in the present invention. It is a schematic sectional drawing which shows one Example of the charging device utilized by this invention.

1. The following describes the reduction reaction in the conventional blast furnace and AK furnace.
FIG. 2 shows the charge distribution in the conventional blast furnace shown in Non-Patent Document 1, and the charge distribution in the AK furnace 22 of the present invention shown in FIG.
A conventional blast furnace, for example, has a brick wall with an inner diameter of 10 m surrounded by an iron skin, and is composed of a furnace bottom part, a morning glory part, a furnace belly part, a shaft part and a furnace port part from the bottom, and has a total height of about 30 m to the furnace port. A tuyere 9 for blowing hot air between the morning glory part and the furnace bottom part is provided (see Non-Patent Document 2, P.283).
In the furnace, iron ore containing sintered ore and coke are charged in layers from the furnace port. The iron content of iron ore reduced with coke reducing agent is discharged from the tap at the bottom of the furnace. Conventionally, in the shaft portion, a coke layer and a sintered ore fusion layer 13 formed in a triangular shape exist in the center of the furnace. In addition, there is a furnace core (Totenman) 14 made of accumulated coke at the bottom. The furnace core 14 supports at least the upper charge from below. However, since the furnace core does not directly participate in the reduction reaction, the space utilization efficiency in the furnace is impaired.

The AK furnace of the present invention has a rectangular horizontal cross section (for example, inner diameter width 4 m × length 10 m) like the AK furnace 22 shown in FIG. This dimension can be changed by the production efficiency (production amount of pig iron / day). However, the short side direction is not changed. As another aspect, a vertical furnace having a flat (for example, elliptical) horizontal section without a core of a blast furnace having a circular section may be used.
Here, the iron ore and charcoal to be charged will be described. The iron ore may be a sintered ore, pellets or biomass. Desirable are sintered ore and pellets excellent in reducibility. Sintered ore has good air permeability if the particle size is 20mm to 50mm. It is sufficient that the pellets have the same degree. Pellets that are preheated and cured in advance are desirable from the viewpoint of air permeability.

  Although it is a carbon material, coal is desirable for the purpose of the present invention, but usually commercially available coal is about 3 mm or less, and it becomes melted and deteriorates in air permeability when heated at 500 ° C. or less. Or the thing granulated to briquette is desirable. In general, coal is inferior in reducing ability to iron ore, so it is used by mixing with coke. From experience, it is desirable that coal is 30Mass% or more and 70Mass% or less, and the remainder is coke. If the coal is less than 30Mass%, it does not conform to the gist of the invention, and if it exceeds 70Mass%, the air permeability of the central portion is deteriorated, and the productivity in the furnace is inferior although not impossible. An example of blending coal with iron ore at the center of the blast furnace is also disclosed in Japanese Patent Laid-Open No. 2000-144218, and it is known that there is no particular problem.

A change in the furnace when the above carbonaceous material and iron ore are charged into the AK furnace of the present invention will be described.
XY cross sections of the rectangular furnace are shown in A, B, and C of FIG. FIG. 5 is a cross-sectional view taken along the line XY in FIG. 4, where A is the vicinity of the furnace opening, B is the vicinity of the shaft, and C is the cross-sectional view near the tuyere. This figure is the same in the case of other cross sections.
FIG. 5A shows a cross section showing the charge from the furnace port to about 500 ° C. The iron ore 10 is charged into the furnace wall, and at the same time, the carbon material 70 is charged into the center. The iron ore 10 is charged on the carbon material part 70 at a constant interval, for example, every 1 m. This is because when the carbon material 70 is coal, a large amount of tar and gas is released by heating at 500 ° C or less at the beginning of charging, so that especially the tar content is absorbed by the charged iron ore layer, This is because it does not adhere. The generated gas is mainly CH ₄ and reduces the surrounding iron ore layer. As the reduction reaction, mainly Fe ₂ O ₃ is reduced with C and H. Molten coal harms the breathability in the furnace, but the presence of coke ensures the breathability.

FIG. 5B shows the state of the charge in the vicinity of the shaft at 500 ° C. to 1200 ° C. When the iron ore covering the upper part of the carbonaceous material 70 shown in FIG. 5A descends, the outer iron ore spreads from the central carbonaceous material, and brim-like portions are generated at predetermined intervals. When the central carbon material 70 is coal, semi-coke 7-1 produced by dry distillation of coal is present, and iron ore 10 is reduced mainly by this coke and CO gas rising from below. The reduction reaction is, for example,
Fe ₃ O ₄ + CO = 3FeO + CO ₂ , CO ₂ + C = 2CO, etc.
C in FIG. 5 shows the state of the charge in the vicinity of the tuyere. There are semi-coke 7-1 at the top of the center and coke 7-2 pillars at the bottom. Usually coke dry distillation is required for about 12 hours. In the case of the AK furnace, in order to guarantee the same productivity as the conventional blast furnace, the unloading time is about 6 hours, but the temperature at the bottom of the furnace is about 1800 ° C, so the coal is sufficiently coke.

In this vicinity, for example, as a severe reduction reaction,
FeO + CO = Fe + CO ₂ , CO ₂ + C = 2CO
Will occur.
A carbon material such as coal and heavy oil is blown from the tuyere with oxygen gas instead of air, and the raceway 15 is formed. Raceway 15 normally extends 1.5m from the furnace wall. For example, the inner diameter of the furnace is about 4 m, and the center of the carbonized coal and the charged coke column are about 1 m in diameter.

As is clear from this point, in the AK furnace of the present invention, there is no furnace core 14 (refer to FIG. 2) mainly composed of coke that exists in the conventional blast furnace. The core 14 in the conventional blast furnace is, for example, a triangle having a diameter of about 8 m and a height of about 8 m at the bottom of the conventional furnace having a diameter of 10 m, and this portion does not directly participate in the reduction reaction. Supports iron ore existing from the bottom to the top. On the other hand, the AK furnace of the present invention can maintain at least the same productivity even if the body diameter is small.
The outline of the reduction reaction in the height direction of the furnace has been described above. An outline of mass balance in the conventional blast furnace and the AK furnace of the present invention will be described.

Referring again to FIG. 2, an overview of carbon mass balance in a conventional blast furnace is described. To produce 1 ton of pig iron
・ Charge from furnace entrance Iron ore (pellet, sintered ore and / or ore) 1600kg / ton Coke 350kg / ton ・ Feed from tuyere 150kg / ton pulverized coal blown with hot air ( (500kg / ton combined with coke charged from the furnace port)
・ Carbon content in pig iron 4.5% 50kg / ton
・ Exhaust gas from furnace port CO, CO ₂ , H ₂ N ₂
From the above calculation, the amount of carbon to be charged = 350 + 150 kg / ton On the other hand, an example of basmalance in the present invention is as follows, as shown in FIG.
・ Charge from furnace opening Iron ore (same as above) 1600kg / ton When coal is coal and coke (however, carbon content) 200kg / ton pulverized coal 175kg
Total 375kg Charged carbon is reduced by 25% compared to the conventional blast furnace.
Since, for example, coal and coke are directly charged as the carbon material, the quality is particularly important in the case of coal, and high-purity coal powder selected from ash is used as much as possible. However, a high tar content is not required.

It is desirable that the coal powder is previously granulated or briquetted with a particle size of 20 mm to 50 mm for convenient transportation and charging. Coal is cheaper than coke, but it is inferior in iron ore reducibility, so a large amount of coal is used to reduce manufacturing costs, and a large amount of coke is used to increase productivity. In this case, it is not desirable in that the amount of CO ₂ discharged from the coke oven increases. Further, when a large amount of coke is used, the air permeability at the center portion is increased and the furnace gas temperature is also increased. Therefore, the temperature is adjusted to a desired range by changing the blending amount of coal and coke.
When coal powder is mixed, the coal powder is melted in the furnace and the air permeability is deteriorated. However, the gas flows from the center portion to the outside and the iron ore or sintered ore in the furnace wall portion is reduced, which is desirable. That is, by changing the blending ratio of coal and coke in the center, the flow rate of gas flowing through the center can be controlled to control the reduction reaction in the furnace. According to the examples, the amount of coal is 30 mass% to 70 mass% with respect to the total amount, and the balance is coke.

In addition, the gas in the furnace is 90% or more of CO gas and CO ₂ gas, and the reduction reaction is promoted by the amount that the gas does not substantially contain N _2. Lowers the construction cost.
In the above, the composition of iron ore and sintered ore is an average composition, for example, iron ore is Fe ₂ O ₃ and other additives, and sintered ore is Fe ₂ O ₃ = 57%, FeO = 7 %, SiO ₂ = 6%, Al ₂ O ₃ = 2%, CaO, MgO and the like.
Also, pulverized coal is blown mainly from the tuyere with oxygen gas of 50 vol% or more, and the amount of gas is reduced compared to the case of air. Provides a tuyere for each gas injection, and heats the exhaust gas (CH ₄ , CO ₂ , Co) from the furnace port to, for example, 1000 ° C or higher, or adds LD gas from the LD converter and heats it to the shaft. The reduction action is improved by blowing.

2. Structure of the reduction furnace used in the method of the present invention As shown in FIG. 4, the reduction furnace of the present invention has a rectangular horizontal cross section, and the hatched portion is a semi-coke produced by heating a carbonaceous material, for example, coal. -1 or coke. The reason why the rectangular shape is used in this manner is to prevent an inactive zone called a furnace core that occurs in the case of a conventional circular cross-section furnace, and it is therefore necessary to reduce the cross-sectional area of the furnace core.
Cross sections in the vertical direction of the furnace are shown in A, B, and C of FIG. FIG. 5 is a cross-sectional view in the XY direction of FIG. 4. FIG. 5A is a cross-sectional view near the top of the furnace, FIG. B is a cross-sectional view near the shaft, and FIG.
Although A, B, and C in FIG. 5 are described as having the same cross section, the volume of the reducing gas decreases as it goes from the bottom to the top. In particular, since the temperature of the shaft portion decreases from the bottom to the top, if the cross-sectional area is the same, the gas rising speed is increased and the reduction reaction time is shortened. Therefore, it is desirable to reduce the rectangular cross-sectional area so that this portion becomes uniform.

In order to charge iron ore to the furnace wall and to charge the carbonaceous material to the center, it is necessary to provide charging means different from the conventional one. In the present invention, the means shown in FIG. 6 is adopted, but the present invention is not limited to this. In FIG. 6, when the iron ore raw material is conveyed onto the small bell 103 at the top of the furnace by the bucket 100, the small valve 105 in the small bell 103 is dropped while being closed, and is stored in the hopper 101 via the small bell 103. Then, the small valve 105 and the large valve 102 are simultaneously opened, and the charcoal is dropped into the furnace through the small valve 105, the conduit 106, and the large bell 104 below the small valve 105.
At this time, the iron ore is accumulated on the furnace wall side as shown in FIGS. 3 and 5, and the carbonaceous material is charged into the center of the furnace. In addition, if iron ore is dropped instead of charcoal at regular time intervals, a cross-sectional shape as shown in FIGS. 3 and 5 is obtained.

On the other hand, coal or coke is dropped from the bucket 100 onto the small bell 103, but the small valve 105 in the small bell is opened, dropped downward through the conduit 106, and dropped from the inside of the large bell 104 to the center of the furnace. , Put in the furnace. In addition, since the rectangular furnace is long in the long axis direction, a plurality of such charging means can be provided in the furnace port longitudinal direction, and the stock line level charge can be leveled in the horizontal direction.
The basic form of the embodiment is that iron ore is charged in the furnace wall, and at the same time, a carbonaceous material (for example, coal) is charged in the center of the furnace, and the coal powder is fed together with oxygen gas from the tuyeres at the bottom of the furnace. Injecting, burning the coal, reducing the iron ore, and producing pig iron. Since the cost of the embodiment in the actual furnace is enormous, simulation reduction is performed with a small-sized furnace with a stainless steel container (inner diameter 200 mm, length 300 mm load reduction test device, similar to the device described in Non-Patent Document 2, P161). went.

The central part was mixed and filled with 50% coal with a diameter of 30 mm and 50% coke, and the surrounding area was filled with 50% pellets and 50% sintered ore. The test was conducted at 500 ° C for 2 hours, 1200 ° C for 2 hours, and 1300 ° C reduction test. That is, the reduction test is a simulation of conditions in the blast furnace. CO gas was supplied from the lower part of the furnace, and gas was discharged from the upper part of the test equipment. As a result, iron ore was reduced smoothly.
In a real furnace, the iron ore is desirably 5 mm to 25 mm to maintain the air permeability in the furnace. Iron ore is easy to ensure air permeability by adjusting the component composition so that reduced powdering is less than that of sintered ore. However, the iron ore can contain 50% or more of sintered ore unless the air permeability in the furnace is impaired.

In addition, it is desirable that the carbonaceous material is a briquette of coke or powdered coal in terms of preventing scattering at the time of carrying in or charging. As already mentioned, some of this coal may be coke. Moreover, you may utilize biomass, such as charcoal, instead of coal.
The oxygen gas is preferably 50 vol% or more in purity. This is because when the purity is 50 vol% or less, the N ₂ gas concentration becomes relatively high, and therefore, the N ₂ content of the furnace port gas is increased and the CO ₂ gas is not reduced.
In the pig iron manufacturing method, the gas from the furnace port is mainly composed of CO ₂ gas and CO gas, and N ₂ gas is about 25 Vol% or less. Therefore, it is desirable to blow down the furnace port gas and / or a reducing gas such as an LD gas, for example, a reducing gas heated to 1000 ° C., for example, at the shaft intermediate portion. When there is CH ₄ discharged from the furnace port, CO ₂ gas from the furnace port can be modified to CO gas. Thereby, the amount of CO ₂ gas generation can be further reduced.

The cross section of the vertical furnace has a rectangular horizontal cross section, with a tuyere part between the furnace bottom part and the morning glory part, and the morning glory part, the furnace belly part, the shaft part at the top of the furnace bottom part, and the furnace mouth part at the top. A vertical furnace for producing pig iron is provided.
The morning glory part and the shaft part are a rectangular furnace for producing pig iron having a cross-sectional area that continuously extends to the furnace bottom and a cross-sectional area that decreases toward the furnace port.
In order to charge iron ore into the rectangular furnace opening, the means is provided on the furnace opening. Further, in the rectangular furnace, the mobile buckets for charging the iron ore on the furnace wall and the carbonaceous material in the central part may be provided.

1 Blast furnace
2 Coke oven
3 Hot air furnace
4 Sintering machine
5 Lime firing furnace
6 Lower process (steel making, rolling, etc.)
7 Charcoal
7-1 Hansei coke
7-2 Coke
9 tuyere
10 Iron ore
13 Melting zone
14 Furnace core
15 Raceway
22 Rectangular furnace
101 bucket
102 Large valve
103 Small bell
104 large bell
105 Small valve
106 Conduits In the figure, the same reference numerals indicate the same or corresponding parts.

Claims (11)

  The iron ore (10) is charged from the furnace port portion into the furnace wall portion of the vertical furnace having the shaft portion, and at the same time, the carbon material (70) is charged into the furnace center portion so that the carbon material (70) So that the iron ore (10) is formed on the outside of the carbon material (70) and pulverized coal is blown together with oxygen gas from the tuyere (9) at the bottom of the furnace. A pig iron production method comprising producing pig iron by burning the pulverized coal to generate a reducing gas and reducing the iron ore with the reducing gas.   The shaft portion is provided with another tuyere for gas injection, and the exhaust gas discharged from the furnace port portion is heated to a predetermined temperature or higher, or the LD gas of the LD converter is added to the exhaust gas to the predetermined temperature or higher. 2. The method for producing pig iron according to claim 1, wherein the iron is heated and then blown into the other tuyere.   2. The pig iron manufacturing method according to claim 1, wherein the iron ore is charged in layers on the carbonaceous material (70) charged in the central portion at a predetermined interval.   2. The pig iron manufacturing method according to claim 1, wherein the iron ore is a mixture of one or more of pellets, sintered ores, and lump ores.   2. The pig iron manufacturing method according to claim 1, wherein the carbon material (70) is one or more of coal, coke, and biomass.   2. The pig iron manufacturing method according to claim 1, wherein the carbon material is a carbon material mixed with 30% by mass or more of coal.   7. The pig iron manufacturing method according to claim 6, wherein the coal is processed into pellets or briquettes.   2. The pig iron manufacturing method according to claim 1, wherein the oxygen gas has a purity of 50 vol% or more. The horizontal section has a rectangular shape (22) or an elliptical shape, and includes a furnace bottom part, morning glory part, furnace belly part, shaft part and furnace mouth part from the bottom, and tuyeres (9) between the furnace bottom part and the morning glory part. )
The iron ore is charged into the furnace wall portion from the furnace port portion, and at the same time, the carbon material (70) is charged from the furnace port portion to the furnace center portion so that the carbon material (70) is columnar in the furnace center portion. Means for forming and forming the iron ore (10) on the outside of the carbon material (70), and blowing pulverized coal together with oxygen gas from the tuyere (9), the carbon material and the pulverized coal And a means for producing pig iron by producing a reducing gas by burning the iron ore and reducing the iron ore with the reducing gas. A vertical pig iron manufacturing furnace comprising:   The exhaust gas from the furnace port is heated to a predetermined temperature or higher, or LD gas of an LD converter is added to the exhaust gas and heated to the predetermined temperature or higher, and another tuyere that is blown into the shaft unit is further provided. 10. The pig iron manufacturing furnace according to claim 9, comprising:   10. The morning glory portion has a cross-sectional area that continuously extends in succession to the furnace bottom portion, and then the shaft portion has a cross-sectional area that gradually decreases toward the furnace port portion. Pig iron making furnace.

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