JP2001323307A - Method for operating of blowing pulverized fine coal into bast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently prevent the formation of a raceway shell by estimating a desirable reaction form between ash content in pulverized fine coal and dripped slag. SOLUTION: The description of coal and the blending or the mixing ratio are decided so that the ash content composition in the blended coal satisfies 0<(%CaO)/(%Al2O3)<0.45, 0.25<(%Al2O3)/(%SiO2)<1.0, (%CaO)+(%SiO2)+(% Al2O3)>70 and the pulverized fine coal ratio in a blast furnace operation, the ash content in the pulverized fine coal, CaO and Al2O3 satisfy the pulverized fine coal ratio (kg/t)<=[100/(%ash)]×[7.5×(<=CaO)/(%Al2O3)+10.8]. The pulverized fine coal is blown at >=180 kg/t. At this time, the blast furnace operation is performed at 280-250 kg/t slag ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized coal injection operation into a blast furnace, and more particularly to a technique for stably injecting a large amount of pulverized coal.

[0002]

2. Description of the Related Art In order to reduce the cost of producing pig iron by reducing the amount of coke used, and to reduce the burden on the coke oven and thereby extend the life of the coke oven, fine powder from tuyeres is used as a partial substitute for coke charged into the blast furnace. A large amount of pulverized coal has been blown into coal blast furnaces. It is desirable that the amount of pulverized coal injected be large, so the amount of injection has been increased.
11 (1998) p834 ”, a blast furnace with an extremely large amount of injection of 266 kg / t-hot metal at a monthly pulverized coal injection ratio has also emerged.

[0003] However, it is known that the air permeability of a blast furnace deteriorates due to the injection of pulverized coal. As pointed out in "Materials and Processes Vol.7 (1994) p.129", the deterioration of air permeability in the lower part of the furnace due to the growth of raceway shells (also called bird's nests) is particularly serious for the stable operation of blast furnaces. This is often a limiting factor in pulverized coal injection.

FIG. 6 is a longitudinal sectional view illustrating a raceway shell formed in front of a tuyere of a blast furnace. FIG. 2B is a partially enlarged view of FIG. The ash contained in the pulverized coal 5 blown from the tuyere 3 of the blast furnace 2 together with the hot air 4 from the tuyere 3 of the blast furnace 2 adheres to the end of the raceway 6 and forms a poor ventilation layer. Ash in pulverized coal is mainly composed of SiO2 and Al2O3, and its melting point is as high as about 1700 ° C. When the amount of pulverized coal injected is small, this raceway shell is assimilated with the slag dripping and disappears, but when the amount of pulverized coal injected increases to about 180 kg per ton of hot metal, it assimilates with the slag. The blast furnace lowers, and deterioration of air permeability becomes remarkable.

In order to suppress the formation of the raceway shell, a method of simultaneously blowing a pulverized coal and a slag-forming agent such as CaO (for example, Japanese Patent Publication No. 6-89382, hereinafter referred to as “prior art 1”), (JP-A-11-152508, hereinafter referred to as "prior art 2") has been proposed.

According to the prior art 1, a basic slag forming agent such as pulverized dolomite, serpentine, peridotite, and limestone is blown at the same time as pulverized coal, and the injected slag forming agent and ash in the pulverized coal are mixed. Basicity at the time (basic component / acid component)
However, there is disclosed a technique that makes the value fall within a range of 0.5 to 1.3. According to this technology, the ash in the pulverized coal and the injected slag forming agent are assimilated in the raceway shell layer to form a low-viscosity slag. Is improved.

According to the prior art 2, the maximum temperature Tmax (° C.) of gas in the raceway and the melting point of ash in pulverized coal
A technique has been disclosed in which the ratio to THT (Tmax / THT) is in the range of 1.0 to 1.5. According to this method, the melting of the ash in the pulverized coal in the raceway is suppressed, so that the growth of the raceway shell is suppressed and the air permeability in the lower part of the blast furnace is improved.

[0008]

SUMMARY OF THE INVENTION Prior Art 1 or 2
According to the method described above, it is possible to suppress the generation of a raceway shell when pulverized coal is blown in a large amount, and it is possible to reduce the pressure loss in the lower part of the blast furnace, but both methods have the following disadvantages. It was found that this was not practically preferable.

In the method according to Prior Art 1, it is necessary to prepare a large amount of dolomite or the like to be used as a slag-making agent, which causes an increase in auxiliary materials and fuel costs. Even if the slag-forming agent can be procured at low cost, the dissolution reaction of these slag-forming agents is generally an endothermic reaction, and lowers the temperature in the raceway. In order to maintain the operation of the blast furnace, it is necessary to appropriately maintain the temperature in the raceway, and it is necessary to increase the amount of expensive oxygen that is enriched during hot air blowing, thereby increasing costs. It will be.

In the method according to Prior Art 2, the amount of oxygen used is increased or decreased in order to control the maximum temperature Tmax (° C.) of the gas in the raceway. It is not always constant, but so-called pulsation (the amount of blowing is periodically increased and decreased). When the amount of pulverized coal injected pulsates, the maximum temperature Tmax (° C.) of the gas in the raceway also pulsates. That is, coke is
The pulverized coal is charged directly from the blast furnace into the raceway without being preheated. Tmax (° C.) decreases, and when the blowing amount decreases, Tmax (° C.) increases. Therefore, the high-melting-point pulverized coal ash generated when Tmax (° C.) rises adheres to the end of the raceway and forms a raceway shell. It is difficult to remove the shell once formed by the method of the prior art 2. Therefore, in order to suppress the generation of the raceway shell using the prior art 2, it is often the case that the pulsation Tm of such a pulverized coal injection amount is increased.
In order to reduce the effect on ax (° C), the amount of pulsation must be measured, and measures such as increasing or decreasing the oxygen enrichment rate must be taken in conjunction with this measure.
It turned out to be unfavorable for practical use.

In view of the above-mentioned problems of the prior art, it is an object of the present invention to form a raceway shell by assuming a desirable reaction form between ash in pulverized coal and dripping slag, and based on this, it is effective in actual operation. By finding conditions that can prevent the formation of raceway shells,
Even when pulverized coal is injected in large quantities, it can be carried out within the range of normal supply and demand of raw materials, and suppresses the generation of raceway shells without incurring an increase in pig iron production costs and without special capital investment. Another object of the present invention is to provide a method of injecting pulverized coal into a blast furnace to improve the permeability of the lower part of the blast furnace and maintain a stable operation of the blast furnace.

[0012]

Means for Solving the Problems The present inventors have intensively studied from the above viewpoint. That is, the composition of fine coal ash,
The melting point, the composition of the dropped slag, and the melting point were investigated, and the formation and growth mechanism of the raceway shell were examined. Table 1 shows the chemical composition and melting point of typical blast furnace slag and ash in coal, and the ash content in the coal.

[0013]

[Table 1]

Regarding the formation mechanism of the raceway shell, it is considered that the ash contained in the pulverized coal exemplified in Table 1 adheres to the end of the raceway and a poor ventilation layer is formed as described above. When the amount of pulverized coal injected is small, the raceway shell assimilates with the slag dripping and disappears, but when the amount of pulverized coal injected increases to about 180 kg per ton of hot metal, the raceway shell It is considered that the shell cannot be completely assimilated with the dripping slag, or the high melting point ash from the pulverized coal cannot be assimilated with the dripping slag, and the deterioration of air permeability in the lower part of the blast furnace becomes remarkable.

FIG. 1 shows a ternary phase diagram of CaO-SiO2-Al2O3. Of the components of ash in coal used to produce pulverized coal that is currently commonly used, Ca
Ratio of three main components of O, SiO2 and Al2O3 (wt.
%), It was found that most of them were within the composition range divided by region A in the figure. In this case, since the ash in the coal has a high melting point of about 1700 ° C., it is easy to form a raceway shell.

The inventors of the present invention have found that the composition of the raceway shell formed by fixing the ash to the raceway end moves in the direction of arrow B in FIG. 1 when CaO is supplied from the drip slag. In this case, a crystal phase of Anorthite was formed, and its melting point dropped to around 1400 ° C, and it was found that it dropped and disappeared (Materials and Process Vol, 9 (1996), p8).
31). As a result of further study, it was noticed that when the composition of the raceway shell was in the region A of FIG. 1, its melting point was substantially dependent on the value of (% CaO) / (% Al2O3). That is, the raceway shell was focused on the fact that the melting point was greatly reduced only by supplying a relatively small amount of the CaO component from the dropping slag. As described above, considering that the formation of the raceway shell is strongly controlled by the amount and composition of the ash in the pulverized coal, Ca
When the three main components of O, Al ₂ O ₃ and SiO ₂ are in the ash in the region A in FIG. 1, (% CaO) / (% Al 2
As the value of (O3) approaches 0.45, the melting point sharply decreases, and the ash having a composition whose (% CaO) / (% Al2O3) value is originally relatively close to 0.45 is
The fact that the melting point decreases sharply due to a slight increase in the value of (% CaO) / (% Al2O3) is considered to mean the following. That is, the ash having a component composition in which CaO, Al 2 O 3 and SiO ₂ belong to the region A is
By supplying a relatively small amount of the CaO component from the dropping slag, the melting point of the ash is greatly reduced, and thus the formation of the raceway shell is suppressed. Furthermore, originally (% Ca
Ash having a composition with a value of O) / (% Al2O3) relatively close to 0.45 has a lower melting point, but due to the supply of a smaller amount of CaO component from the dropping slag, the melting point of the ash is It was noted that the melting point could be further reduced significantly, and as a result the melting point could be reduced more cumulatively. As described above, the lower the melting point of the ash, the more the formation of the raceway shell is suppressed, and even if the raceway shell is formed, it is noticed that the CaO component in the drip slag can be supplied and disappear. did.

The present inventors have conducted the following tests and studies based on the above viewpoint. The ash content (%) takes various values from among the brands of coal commonly used for pulverized coal production, and the ash component composition takes various component compositions in the region A in FIG. As described above, it was prepared with a single brand of coal or with a blended coal obtained by mixing various brands of coal using a plurality of brands of coal. The component composition of the ash in the coal represented in the area A in FIG. 1 is represented by the simultaneous equations (1) and (2).

[0018] 0 <(% CaO) / ( % Al 2 O 3) <0.45 ............ (1) 0.25 <(% Al 2 O 3) / (% SiO 2) <1.0 ............ (2) A single brand of coal having the above-mentioned various component compositions or a blend of multiple brands of coal was pulverized to prepare each pulverized coal. Using the pulverized coal thus obtained, a pulverized coal ratio of 180 kg / t-
A blast furnace test operation was performed with a large amount of pulverized coal injected over hot metal.

The ash input AR of the pulverized coal and the ash input ARmax from the pulverized coal at the limit where the operation of the blast furnace becomes unstable from stable operation are defined by equations (5) and (6).

AR≡PCR × (% Ash) / 100 (5) ARmax≡PCRmax × (% Ash) / 100 (6) where, PCR: pulverized coal ratio (kg / t-hot metal) ) PCRmax: PCR at the limit of operation failure (kg / t-hot metal) Here, the definition of operation failure is to increase the pulverized coal ratio PCR little by little (for example, 2-3 kg / t-hot metal per day). And the slip (discontinuous drop of the blast furnace interior) occurs three times a day or more.

In the above test, it was found that the operation malfunction occurred.
(% CaO) / (% Al_TwoO _Three) On the horizontal axis, then
When the ARmax of the graph is arranged on the vertical axis, as shown in FIG.
A clear linear relationship was obtained. Least square method
Equation (7) was obtained by mathematical expression.

ARmax = 7.5 × {(% CaO) / (% Al ₂ O ₃ )} + 10.8 (7) However, the components of ash in pulverized coal include CaO, Al ₂ O ₃ and SiO ₂ In addition to MgO and iron oxide, formula (7) holds with high accuracy because the component composition of ash in pulverized coal is (% CaO) + (% SiO ₂ ) + (% Al ₂ O ₃ ) > 70 Only when the condition of (3) is satisfied, otherwise a good linear relationship could not be obtained. However,
Most of the commonly used pulverized coal for blowing into a blast furnace have an ash composition satisfying the formula (3).

In the above test, the expression (7)
In the blast furnace, a large amount of pulverized coal
Furnace permeability deteriorates due to sway shell formation
Analysis of the factors that hinder stable operation.
And one of the main components of ash in pulverized coal, SiO_TwoContained
As long as the commonly used pulverized pulverized coal is used,
It does not hinder the stable operation of the blast furnace.
And there. In this way, blast furnace operation has shifted from stable operation to
Ash content from pulverized coal at the time of
When determining the pulverized coal injection ratio, pulverized coal
SiO from medium ash _TwoThe charging speed (kg / t-hot metal)
On the other hand, no special restrictions need to be set,
SiO in the ash_TwoSpecial restrictions on the content of components
The finding that it is not necessary is to prevent the formation of raceway shells.
(% CaO) /
 (% Al_TwoO_ThreeIt is clear that we should pay attention to the value of
This is a noteworthy finding.

In order to continue the stable pulverized coal injection operation, the following equation (8) must be satisfied: ARmax ≧ AR (8). Substituting Equations (7) and (5) for each of the ARs, the pulverized coal injection ratio PCR is calculated by the following equation (4) in order to continue the pulverized coal injection operation to prevent operation failure. It is necessary to satisfy PCR ≦ {100 / (% Ash )} × [7.5 × {(% CaO) / (% Al 2 O 3)} + 10.8] ............ (4)

Next, the present inventors considered the assimilation and disappearance behavior of the raceway shell once formed by the dripping slag, and the (% CaO) / (% Al2O3) of the ash component in the common pulverized coal.
) And the melting point of the ash, and an operational test that focuses on the possibility of reducing the allowable limit for dropping slag from these findings, that is, a test combining the reduction of the blast furnace slag ratio. Was performed. As a result, it has been found that even if the blast furnace slag ratio is reduced within a predetermined range, the assimilation and disappearance of the raceway shell can be ensured.

The present inventors have devised the present invention based on the above findings. The summary is as follows.

The method for injecting pulverized coal into a blast furnace according to the first aspect of the present invention is obtained by blending, mixing and pulverizing a single brand of coal or a plurality of brands of coal. In the operation method of pulverized coal injection into a blast furnace, in which pulverized coal is injected at a pulverized coal ratio of 180 kg / t-hot metal or more, determination of the brand and blending ratio of coal for pulverized coal production and pulverized coal produced from the coal thus determined It is characterized in that the determination of the coal blowing speed is performed as follows. That is,
As a method of blending coal, the ash composition in a single brand coal or a blended coal of a plurality of brands of coal is determined by the following (1) to (3).
Wherein: 0 <(% CaO) / (% Al 2 O 3) <0.45 ......... (1) 0.25 <(% Al 2 O 3) / (% SiO 2) <1.0 ......... (2) (% CaO ) + (% SiO ₂ ) + (% Al ₂ O ₃ )> 70 (3). Moreover, pulverized coal ratio in blast furnace operation, ash content in pulverized coal, and Ca in pulverized coal
The content of O and Al ₂ O _{3 is} determined by the following formula (4): PCR ≦ {100 / (% Ash)} × [7.5 × {(% CaO) / (% Al ₂ O ₃ )} + 10.8] ……… (4) However, PCR: pulverized coal ratio (kg / t-hot metal) (% Ash): ash content in pulverized coal (wt%) (% CaO): CaO content of ash in pulverized coal (wt%) (% Al ₂ O ₃ ): brand of coal used as pulverized coal so as to satisfy the Al ₂ O ₃ content (wt%) of ash in pulverized coal,
The present invention is characterized in that the blending ratio of coal or the mixing ratio of the brand of coal and each brand is determined.

The method for injecting pulverized coal into a blast furnace according to the second aspect of the present invention is the same as the method for injecting pulverized coal into a blast furnace according to the first aspect, wherein the slag ratio of the blast furnace is 280 to 250 k.
It is characterized in that it operates within the range of g / t-hot metal.

[0029]

Next, preferred embodiments of the present invention will be described. As shown in FIG. 3, pulverized coal 5 is blown into the furnace together with hot air 4 from a blowing blow pipe 7 provided in connection with the tuyere 3 of the blast furnace 2. As a pulverized coal 5 injection lance, the unburned char is accumulated in the furnace core and the cohesive zone root by improving the combustion rate of the pulverized coal 5 and reducing the amount of unburned char generated in the raceway. In order to suppress the deterioration of ventilation and liquid permeability in the furnace, for example, a pulverized coal blowing lance 8 as shown in FIGS. A heavy pipe is inserted, pulverized coal is blown from the inner pipe, oxygen is blown from the outer pipe, and the directions of the axial center 9 of the lance are not crossed. FIG. 5 is a view taken in the direction of the arrows AA in FIG. Thus, it is desirable to use a pulverized coal injection lance 8 which is appropriately designed.

As the coal for the production of pulverized coal, a brand which is not suitable as a raw coal for the production of coke charged into a blast furnace is mainly used. Therefore, the ash content in the pulverized coal for injection is generally high, and the composition of the ash in the pulverized coal has various levels. However, the main components of the ash are _three components of Al ₂ O ₃ , SiO ₂ and CaO, of which CaO has a relatively low content, and the ratio of the three components for many brands of coal is as follows: A shown in FIG.
In the ternary phase diagram of l ₂ O ₃ —SiO ₂ —CaO, the region A
I confirmed that I got inside.

Therefore, a single brand of coal is selected, or a plurality of brands of coal are blended and mixed, and then pulverized to produce pulverized coal for injection into a blast furnace. Pulverized coal ratio 1
A blast furnace operation in which pulverized coal of 80 kg / t-hot metal or more is blown. Blending the pulverized coal for coal ash composition of the formulation in coal, 0 <(% CaO) / (% Al 2 O 3) <0.45 and, 0.25 <(% A
l ₂ O ₃ ) / (% SiO ₂ ) <1.0 (% CaO) + (% SiO ₂ ) + (% Al ₂ O ₃ )> 70 (3) The reason for limiting the component composition of the blended coal so as to satisfy the above two formulas is that coal of a commonly used brand has an ash component within the range, so that the method of the present invention is limited to have versatility. Condition. The pulverized coal injection operation is performed under such conditions. At that time, the pulverized coal ratio PCR (kg / t-hot metal) and the ash content (As
h) As content and CaO and Al ₂ O ₃ content in pulverized coal, PCR ≦ {100 / (% Ash)} × [7.5 × Δ (% CaO) / (% Al
₂ O ₃ )｝ 1 10.8], the brand of coal used as pulverized coal,
The blending ratio of coal or the blending ratio of the brand of coal and each brand is determined. By selecting and blending coal for pulverized coal so as to satisfy the relational expression, the pulverized coal injection ratio is 180
This is because even if the pressure is not less than kg / t-hot metal, stable operation with air permeability secured can be performed. However, it is necessary that the ash component in the pulverized coal satisfies (% CaO) + (% SiO ₂ ) + (% Al ₂ O ₃ )> 70. In addition, the blast furnace slag ratio is 280-
It is more desirable to operate in the range of 250 kg / t-hot metal. By doing so, the air permeability of the blast furnace can be further ensured, and furthermore, it contributes to reducing the hot metal production cost in the blast furnace.

When the pulverized coal to be used to be used is given in advance in the blast furnace operation process, the pulverized coal injection ratio PCR becomes PCR ≦ {100 / (% Ash)} × [7.5 ×
By determining the amount of pulverized coal to be blown so as to satisfy {(% CaO) / (% Al ₂ O ₃ ) + 1 + 10.8], it is possible to perform a stable operation with air permeability in the blast furnace.

[0033]

EXAMPLES The present invention will be further described with reference to examples. In a blast furnace with a furnace volume of 3443 m ³ , the output of coke is 6,900 tons / day, the slag ratio is 265 kg / t, the blast temperature is 1150 ° C, and the oxygen enrichment rate is 4%. In terms of supply and demand, the coke ratio had to be about 300 kg / t, and the target for pulverized coal injection had to be about 250 kg / t.

Therefore, in order to maintain stable operation under the operating conditions on the premise that such a large amount of pulverized coal is blown, the brand of coal to be used as pulverized coal and its blending ratio are determined by determining the ash content of the blended coal. And the ash content (% CaO) /
(% Al ₂ O ₃ ) was determined and tested so as to satisfy the above-described equation (4) (Examples 1 to 3). In addition, a test was also performed for the case where the expression (4) was not satisfied with a small difference (Comparative Example 1).
The operating conditions of Examples 1 to 3 and Comparative Example 1, the blending ratio of coal used in the production of pulverized coal for injection, the upper limit of the pulverized coal injection ratio PCR limited by equation (4), and the blended coal Table 2 shows the calculated values of the right side of the equations (1) to (3) based on the component compositions.

However, the coals selected here are coal brand A and coal brand B shown in Table 1, and the component composition of the ash contained in each has already been described in (3) above as shown in Table 3.
To (3) are satisfied.

[0036]

[Table 2]

[0037]

[Table 3]

Under the operating conditions and test conditions of Examples 1 to 3 and Comparative Example 1, a test of blowing a large amount of pulverized coal into a blast furnace was performed. The quality of the operation was determined based on whether or not the occurrence of the slip phenomenon was within 2 times / day. The results of the determination are also shown in Table 2.

The test results will be described below. Example 1
Is a case where coal brand B is used alone as pulverized coal. According to equation (4), which is a necessary condition for stable operation, the upper limit of the pulverized coal injection ratio when coal brand B is used is 294 kg.
/ t-hot metal, Example 1 was within the scope of the present invention, and the blast furnace operation changed favorably.

In general, coal having low ash content such as coal brand B is expensive. Therefore, in Examples 2 and 3 and Comparative Example 1, relatively cheap coal brand A is blended with coal brand B. It was to be. Example 2 is a case where 5% of coal brand A and 95% of coal brand B are used as pulverized coal,
Example 3 is a case where 10% of coal brand A and 90% of coal brand B are used as pulverized coal. According to the formula (4), the upper limit of the pulverized coal injection ratio when each of the blended coals is used is 274 kg / t-hot metal in Example 2, and 254 kg / t-hot metal in Example 3. kg / t-hot metal, which was within the scope of the present invention, and the blast furnace operation was favorable.

As described above, according to the present invention, it is possible to increase the use of brand A, which is an inexpensive coal when pulverized coal is injected.

On the other hand, in Comparative Example 1, 15% of coal brand A and 85% of coal brand B were used as pulverized coal beyond the scope of the present invention.
This is the case when used. That is, according to Equation (4), Comparative Example 1
The upper limit of the pulverized coal injection ratio when using
kg / t, and 250 kg / t cannot be blown to maintain stable operation. In Comparative Example 1, since 250 kg / t was blown in contrast, the slip phenomenon was 3
More than once per day, blast furnace operation was sluggish.

In order to stably perform the pulverized coal injection operation at a pulverized coal ratio of 250 kg / t by blending coal brand A and coal brand B, the upper limit of the mixing ratio of coal brand A is given by equation (4). Is estimated to be about 11%.

[0044]

As described above, according to the present invention, it is possible to suppress the formation of the raceway shell even in the operation of injecting a large amount of pulverized coal by using ordinary coal used for pulverized coal for injection. A suitable coal blend can be made. Further, the formation of the raceway shell can be suppressed even under low blast furnace slag ratio operation conditions. Therefore, it is possible to improve the permeability of the lower part of the blast furnace,
Even when pulverized coal is injected in a large amount, stable blast furnace operation can be maintained. In addition, there is no need for special capital investment.

Accordingly, it is possible to reduce the cost of producing pig iron and to efficiently use coal resources, and it can also contribute to extending the life of the coke oven. An operation method for pulverized coal injection into such a blast furnace can be provided, and an extremely industrially advantageous effect is brought about.

[Brief description of the drawings]

FIG. 1 shows a condition for easily assimilating ash contained in coal for pulverized coal by dropping slag by CaO—SiO2-A.
It is explanatory drawing for studying using the three-dimensional system equilibrium diagram of l2O3.

Fig. 2 Upper limit of pulverized coal injection ratio at which stable operation can be maintained by securing air permeability in the furnace, and (% Ca
5 is a graph showing that there is a linear relationship between (O) / (% Al ₂ O ₃ ).

FIG. 3 is a schematic vertical sectional view illustrating a method of injecting pulverized coal into a blast furnace.

FIG. 4 is a schematic longitudinal sectional view illustrating an example of a desirable pulverized coal injection lance used in the present invention.

FIG. 5 is a view taken in the direction of the arrows AA in FIG. 4;

FIG. 6 is a longitudinal sectional view schematically illustrating a raceway shell formed in front of a tuyere of a blast furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raceway shell 2 Blast furnace 3 Tuyere 4 Hot air 5 Pulverized coal 6 Raceway 7 Blow pipe 8 Pulverized coal injection lance 9 Shaft center 10 Coke

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuro Ariyama 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Shinji Matsubara 1-2-1, Marunouchi, Chiyoda-ku, Tokyo No. Nippon Kokan Co., Ltd. (72) Inventor: Koji Mori 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Shoka Hayasaka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. F-term (reference) 4K012 BE01 BE09

Claims (2)

[Claims] 1. A single brand of coal is selected or a plurality of brands of coal are blended and mixed, and then pulverized, and the obtained pulverized coal is blown at a pulverized coal ratio of 180 kg / t-hot metal or more.
In the operation method of pulverized coal injection into a blast furnace, the blending of the coal is such that the ash composition in the blended coal after blending is expressed by the following formulas (1) to (3): 0 <(% CaO) / (% Al ₂ O ₃ ) <0.45 ... (1) 0.25 <(% Al ₂ O ₃ ) / (% SiO ₂ ) <1.0 ... (2) (% CaO) + (% SiO ₂ ) + (% Al ₂ O ₃ )> 70 ... (3), and the pulverized coal ratio, ash content in pulverized coal, and CaO and A in pulverized coal in the blast furnace operation described above.
l ₂ O ₃ content is the following formula (4): PCR ≦ {100 / (% Ash)} × [7.5 × {(% CaO) / (% Al ₂ O ₃ )} + 10.8] ……… (4 However, PCR: Pulverized coal ratio (kg / t-hot metal) (% Ash): Ash content of pulverized coal (wt%) (% CaO): CaO content of ash in pulverized coal (wt%) (% Al ₂ O ₃ ): Brand of coal used as the pulverized coal, blending ratio of coal, or brand of coal and each brand, so as to satisfy the Al ₂ O ₃ content (wt%) of ash in pulverized coal A method for injecting pulverized coal into a blast furnace, characterized by determining the mixing ratio of pulverized coal. 2. The method according to claim 1, wherein the slag ratio of the blast furnace is 280 to 250 kg /.
A method for injecting pulverized coal into a blast furnace, which additionally operates within the range of t-hot metal.